# Hawaii’s Active Volcanoes: Federal Role in Research, Monitoring, and Warning

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URL: https://www.frixlaw.com/law-library/documents/crs%3AR48622

## Record

- **Collection:** Congressional research report
- **Document type:** Reports
- **Published:** August 12, 2025
- **Citation:** R48622

## Text

Hawaii’s Active Volcanoes: Federal Role in
Research, Monitoring, and Warning
August 12, 2025

Congressional Research Service
https://crsreports.congress.gov
R48622

SUMMARY

Hawaii’s Active Volcanoes: Federal Role in
Research, Monitoring, and Warning
Hawaii has six active volcanoes, five of which the U.S. Geological Survey (USGS) considers
threatening to people and property. Hawaii’s volcanoes formed the Hawaiian island chain from a
hotspot plume over millions of years, and all of the islands are composed of one or more shield
volcanoes. On the island of Hawaiʻi, Kīlauea volcano is among the most active volcanoes in the
world. It sits on the flank of Mauna Loa volcano, which is also among the world’s most active
and largest volcanoes. Some of the greatest risks from Hawaii’s volcanoes include lava flows,
volcanic bombs, volcanic gases, and volcanic ash. Hawaii also faces risks from earthquakes,
landslides, and tsunamis, some of which may be generated by volcanic activity.

R48622
August 12, 2025
Linda R. Rowan
Analyst in Natural
Resources and Earth
Sciences

Congress has directed federal agencies such as the USGS and the National Oceanic and Atmospheric Administration
(NOAA) to research, monitor, and warn about volcanic hazards affecting the United States. In 2019, Congress passed
legislation that authorized a National Volcano Early Warning and Monitoring System (NVEWS; Section 5001 of P.L. 116-9,
43 U.S.C. 31k). The law directed the USGS to establish NVEWS to monitor volcanoes, warn U.S. citizens of volcanic
activity, and protect citizens from “undue and avoidable harm.” In 2020, the USGS submitted a five-year plan for
establishing and managing NVEWS, and from 2021 to 2024 the agency submitted annual reports charting the progress of
NVEWS. In 2024, the USGS published its Volcano Science Center Response Plan for Significant Volcanic Events. In 2022,
Congress amended NVEWS to direct cooperation and coordination between USGS’s NVEWS and NOAA’s activities to
monitor and warn about volcanic activity impacting the atmosphere and ocean, especially NOAA’s Volcanic Ash Advisory
Centers (VAACs) (P.L. 117-263). In 2025, NOAA submitted an implementation plan to modernize NVEWS in collaboration
with the USGS.
The USGS Hawaiian Volcano Observatory (HVO) studies, monitors, forecasts, warns about, and seeks to reduce risks from
volcanic hazards in Hawaii. With partners, HVO also monitors and informs about earthquakes as the lead for the Hawaii
Integrated Seismic Network. In addition, HVO, NOAA’s Washington Volcanic Ash Advisory Center (WVAAC, located in
College Park, MD, outside of Washington, DC), and other partners study, monitor, forecast, and warn about volcanic gas and
ash hazards in the atmosphere to reduce risks to people, property, vessels, and aircraft. The Hawaii Interagency Vog
Information Dashboard warns about volcanic gases and volcanic smog (i.e., vog).

Considerations for Congress
Congress may consider continued oversight of the USGS Volcano Hazards Program (VHP) and, more specifically, of
NVEWS. Congress may consider VHP’s plans, progress, and priorities; annual and any potential supplemental appropriations
for VHP; potential reauthorization of appropriations for NVEWS (authorized appropriations expired in FY2023) and
amendments to NVEWS. Since the establishment of NVEWS, the USGS generally has divided VHP’s activities into volcano
threat assessments, operational support, the Volcano Disaster Assistance Program, and NVEWS activities. Most of the
research, monitoring, and warning conducted by HVO is supported by NVEWS. Congress provided supplemental
appropriations for new HVO facilities and the repair or replacement of monitoring equipment after the damaging 2018
Kīlauea eruption. Congress may consider how HVO is being modernized and unified with other observatories and whether
HVO is able to monitor volcanoes in its area of responsibility (i.e., Hawaii and American Samoa) to help prevent undue
harm, a primary objective of NVEWS.
The 119th Congress may consider the future of authorizations and appropriations for various federal agencies to research,
monitor, and warn about volcanic hazards affecting the United States. S. 1052, introduced on March 13, 2025, would
reauthorize appropriations for the USGS of $75 million until FY2033. It also would extend the period of authorization of
sums necessary for NOAA to carry out its NVEWS activities to FY2034. S. 1052 would amend NVEWS by adding
“infrasound arrays, visible and infrared cameras and advanced digital telemetry networks” to the emerging technologies the
USGS should apply to modernize the system. Another measure, H.R. 3176, introduced on May 5, 2025, would reauthorize
NVEWS appropriations of $55 million to the Secretary of the Interior for FY2026 to FY2030. Congress may continue to
evaluate the efficiency and effectiveness of NVEWS activities in maintaining the nation’s preparedness and reducing
volcanic hazards’ impacts on lives, property, aviation, maritime activities, and the economy.

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Hawaii’s Active Volcanoes: Federal Role in Research, Monitoring, and Warning

Contents
Introduction ..................................................................................................................................... 1
Primer on Hawaii’s Active Volcanoes and Hazards ........................................................................ 3
Hawaiian Volcanic Risks ........................................................................................................... 6
Kīlauea Volcano ...................................................................................................................... 12
Mauna Loa Volcano ................................................................................................................ 19
National Volcano Early Warning and Monitoring System ............................................................ 22
Federal Research, Monitoring, and Warning in Hawaii ................................................................ 23
Hawaiian Volcano Observatory ............................................................................................... 23
Research ............................................................................................................................ 25
Monitoring ........................................................................................................................ 26
Earthquake Monitoring and Reporting ............................................................................. 29
Warnings ........................................................................................................................... 29
Washington Volcanic Ash Advisory Center ............................................................................ 32
Research ............................................................................................................................ 34
Monitoring ........................................................................................................................ 36
Warning ............................................................................................................................. 37
Hawaii Interagency Vog Information Dashboard .......................................................................... 38
Island of Hawaiʻi Interagency Operation Plan for Volcanic Eruption ........................................... 39
Other Volcano Warning Products in Use in Hawaii....................................................................... 43
Communication of Volcano Warning Products in Hawaii ............................................................. 45
Congressional Considerations ....................................................................................................... 45
Plans and Progress................................................................................................................... 46
Appropriations and Proposed Amendments ............................................................................ 46

Figures
Figure 1. USGS Threat Assessment of Five Active Volcanoes in Hawaii ....................................... 4
Figure 2. Emperor-Hawaiian Chain and Hot Spot Plume Model .................................................... 5
Figure 3. Schematic of Volcanic Hazards from Hawaii’s Shield Volcanoes ................................... 7
Figure 4. Volcanoes on the Island of Hawaiʻi .................................................................................. 8
Figure 5. Earthquakes on the Island of Hawaiʻi with a Magnitude of 6+ During the 19th
and 20st Centuries ....................................................................................................................... 10
Figure 6. USGS Seismic Hazard Model for Hawaii ....................................................................... 11
Figure 7. Some Submarine Landslides in Hawaii ......................................................................... 12
Figure 8. Lava Flows from Kīlauea Volcano, 1750 to 2018 .......................................................... 13
Figure 9. Volcanic Hazards from Kīlauea Eruptions ..................................................................... 15
Figure 10. 2018 Kīlauea Eruption: Map of Part of Volcano and Lava Flows................................ 17
Figure 11. 2018 Summit Collapse at Kīlauea Volcano .................................................................. 18
Figure 12. Hawaiʻi Volcanoes National Park, Kīlauea Summit Map ............................................. 19
Figure 13. Mauna Loa Shield Volcano: Photograph and Graphic ................................................. 20
Figure 14. Mauna Loa Lava Flow Hazards ................................................................................... 21
Figure 15. U.S. Volcano Observatories and Areas of Responsibility ............................................ 25

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Hawaii’s Active Volcanoes: Federal Role in Research, Monitoring, and Warning

Figure 16. Volcano Monitoring ..................................................................................................... 28
Figure 17. USGS Alert-Level Terms for a Volcano ....................................................................... 30
Figure 18. USGS Aviation Color Codes for Volcanic Activity...................................................... 30
Figure 19. Volcanic Ash Advisory Centers: Areas of Responsibility ............................................ 34
Figure 20. Example of a Volcanic Ash Graphic from NOAA’s
Washington Volcanic Ash Advisory Center ............................................................................... 38
Figure 21. Island of Hawaiʻi: Land Management .......................................................................... 42

Tables
Table 1. Island of Hawaiʻi: Volcanic Warning Products and Authorities ....................................... 43
Table D-1. Some Observations and Models Used by
International Airways Volcano Watch ........................................................................................ 57

Appendixes
Appendix A. Acronyms Used in This Report ................................................................................ 49
Appendix B. Volcano Terms .......................................................................................................... 51
Appendix C. Impacts of the 2018 Kīlauea Eruption ..................................................................... 55
Appendix D. Some Observations and Models Used by International Airways Volcano
Watch .......................................................................................................................................... 57

Contacts
Author Information........................................................................................................................ 57

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Introduction
The United States has 170 potentially active volcanoes, and the U.S. Geological Survey (USGS)
considers 161 of these volcanoes threatening.1 According to the Smithsonian Institution’s Global
Volcanism Program, the United States has the most active volcanoes of any country.2 Hawaii has
six active volcanoes, five of which the USGS considers to be threatening (see “Primer on
Hawaii’s Active Volcanoes and Hazards”). People and property close to Hawaii’s active
volcanoes face the greatest risks from lava flows, fire fountains, volcanic ejecta or bombs,
volcanic gases, and volcanic ash (Appendix B).3 Volcanic gases and ash from Hawaii’s active
volcanoes may harm human health and the environment and may damage property, maritime
activities, and aviation.
Hawaii’s active volcanoes typically have a low volcanic explosivity index (VEI) of 0 for
nonexplosive or 1 for small explosivity, so that volcanic ash from Hawaii’s volcanoes generally is
not a significant hazard beyond the eruption site.4 Vog, volcanic smog created by sulfur dioxide
and other volcanic gases, poses a more significant risk to human health and the environment
beyond an eruption site in Hawaii (Appendix B). In addition to these volcanic hazards, Hawaii
may experience earthquakes, landslides, and tsunamis, some of which may be caused by the
growth and activity of the state’s volcanoes.5 Hawaii’s active volcanoes have added risks from
volcanic activity that intersects with the Pacific Ocean, such as laze plumes (Appendix B) and
tsunamis.6

1 A 2018 U.S. Geological Survey (USGS) threat assessment considered active volcanoes that may pose a threat to

people or property. The USGS considered active volcanoes to include volcanoes that have erupted within the past
approximately 11,000 years plus “three notably large and long-lived caldera systems (Yellowstone, Wyoming; Valles,
New Mexico; and Long Valley, California).” The three large caldera systems have not erupted in the past 11,000 years
but may erupt in the future. John W. Ewert et al., 2018 Update to the U.S. Geological Survey National Volcanic Threat
Assessment, USGS, Scientific Investigations Report 2018-5140, 2018, https://doi.org/10.3133/sir20185140 (hereinafter
USGS, Volcanic Threat Assessment, 2018).
2 The Smithsonian Institution’s Global Volcanism Program defines active volcanoes as volcanoes that have erupted in
the past 12,000 years. The other top-five nations with the most active volcanoes include Japan (120), Russia (115),
Indonesia (108), and Chile (91). Smithsonian Institution Global Volcanism Program, “Which Countries Have the Most
Volcanoes?,” https://volcano.si.edu/faq/index.cfm?question=countries.
3 Of these risks, volcanic ash eruptions are rarer events at Hawaii’s active volcanoes and may catch people by surprise.
USGS, “Questions About Volcanic Ash and Other Tephra from Kīlauea,” https://www.usgs.gov/observatories/
hawaiian-volcano-observatory/questions-about-volcanic-ash-and-other-tephra-kilauea.
4 The volcanic explosivity index (VEI) provides a relative measure of the amount of erupted ash and may be useful for
assessing the relative risks of ash and ashfall to people, property, and aviation. VEI does not measure the amount of
erupted lava and is not useful for assessing the risks of lava flows or other ground-based hazards. USGS, “The
Volcanic Explosivity Index: A Tool for Comparing the Sizes of Explosive Volcanic Eruptions,” https://www.usgs.gov/
observatories/yvo/news/volcanic-explosivity-index-a-tool-comparing-sizes-explosive-volcanic. Large to very large
explosive eruptions (VEI of 4 to 8) may have global impacts on climate; modern technologies, such as satellites,
telecommunications, power infrastructure, and aviation; and other aspects of modern society with global
interdependencies. Such impacts are not discussed in this report. For an overview, see Chris Newhall et al.,
Anticipating Future Volcanic Explosivity Index (VEI) 7 Eruptions and Their Chilling Impacts, Geosphere 2018, vol. 14,
no. 2 (February 28. 2018), pp. 572-603, https://doi.org/10.1130/GES01513.1 (hereinafter Newhall, Anticipating Future
Eruptions). Alaska’s volcanoes typically have a VEI of 2 to 3, with some eruptions having a VEI from 4 to 6. Eruptions
with a VEI of 5 to 8 are not common in the global record of volcanic eruptions. See CRS Report R48529, Alaska’s
Active Volcanoes: Federal Role in Research, Monitoring, and Warning, by Linda R. Rowan.
5 USGS, Hawaiian Volcano Observatory (HVO), “Hazards,” https://www.usgs.gov/observatories/hvo/science/hazards.
6 A laze plume forms when hot lava hits the ocean and consists of hydrochloric acid, steam, and fine volcanic glass
particles.

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Research, monitoring, and warning about volcanoes may reduce the risk from volcanic,
earthquake, landslide, and tsunami hazards. It also may identify where hazards from volcanic
activity may threaten people and property. Additional information may help authorities take
protective actions to reduce risks. These actions may include evacuations; shelter-in-place orders;
land, air, or water restricted areas; closures; suspensions or changes to operations; property
relocation; and, where possible, the removal of ashfall deposits to prevent further damage to
people, property, or infrastructure.
Congress has directed federal agencies such as the USGS and the National Oceanic and
Atmospheric Administration (NOAA) to research, monitor, and warn about volcanic hazards
affecting the United States and other countries. The mission of the USGS Volcano Hazards
Program (VHP) is to enhance safety and minimize disruption from volcanic eruptions, and
NOAA’s Volcanic Ash Advisory Centers (VAACs) keep the aviation community informed of
volcanic hazards.7 In 2019, Congress passed the John D. Dingell Jr. Conservation, Management,
and Recreation Act (P.L. 116-9), which authorized the establishment of the National Volcano
Early Warning and Monitoring System (NVEWS).8 The objectives of NVEWS are to organize,
modernize, and unify the monitoring systems of volcano observatories and to monitor U.S.
volcanoes at a level commensurate with their threat. The Volcano Science Center (VSC) within
VHP oversees the five U.S. observatories (Alaska, California, Cascades, Hawaiian, and
Yellowstone), and VSC is leading the effort to establish and manage NVEWS.9
In 2022, Congress passed the James M. Inhofe National Defense Authorization Act for Fiscal
Year 2023 (P.L. 117-263), in which Title CV, Section 10501, amended NVEWS to strengthen the
monitoring and warning systems of U.S. volcano observatories by integrating relevant capacities
of NOAA, including the VAACs.
This report focuses on the USGS’s and NOAA’s roles in research, monitoring, and warning for
Hawaii’s active volcanoes and how these efforts may meet the objectives of NVEWS. The
primary USGS and NOAA-led organizations include the following:
•
•

The USGS Hawaiian Volcano Observatory (HVO) is responsible for volcano and
earthquake monitoring in Hawaii and volcano monitoring in American Samoa.10
HVO leads the Hawaii Integrated Seismic Network (HISN) for earthquake
monitoring, and HISN is part of the U.S. Advanced National Seismic System
(ANSS). Partners in HISN include the NOAA Pacific Tsunami Warning Center,
USGS National Strong-Motion Project, EarthScope Consortium (formerly
Incorporated Research Institutions for Seismology), and Infrasound Laboratory
University of Hawaiʻi.11

7 USGS, “Volcano Hazards Program,” https://www.usgs.gov/programs/VHP/what-we-do-volcano-hazards-program;

National Oceanic and Atmospheric Administration (NOAA), “Volcano Ash Advisory Centers (VAAC),”
https://www.ospo.noaa.gov/products/atmosphere/vaac/other-vaacs.html.
8
Title V, §5001, of the John D. Dingell Jr. Conservation, Management, and Recreation Act (P.L. 116-9) authorized the
National Volcano Early Warning and Monitoring System (NVEWS). For more information, see CRS In Focus
IF11987, The National Volcano Early Warning and Monitoring System, by Linda R. Rowan.
9 P.L. 116-9, the John D. Dingell Jr. Conservation, Management, and Recreation Act, directed the USGS to unify and
modernize the volcano observatories. The USGS chose the Volcano Science Center, which oversees the five
observatories, to lead the implementation of NVEWS. USGS, “Volcano Hazards Program,” https://www.usgs.gov/vhp;
USGS, “Volcano Science Center,” https://www.usgs.gov/centers/volcano-science-center.
10 USGS, “Hawaiian Volcano Observatory,” https://www.usgs.gov/observatories/hvo.
11 USGS, “Monitoring Earthquakes in Hawaii,” https://volcanoes.usgs.gov/observatories/hvo/
hvo_monitoring_earthquakes.html; NOAA, “U.S. Tsunami Warning System,” https://www.tsunami.gov/; USGS,
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•

•

NOAA Washington VAAC is responsible for warning aviation of volcanic
hazards from Hawaii’s active volcanoes and from other U.S. volcanoes, except
those in Alaska and the Northern Mariana Islands.12
The Hawaii Interagency Vog Information Dashboard—a partnership between the
USGS, NOAA, the U.S. Department of Agriculture, the National Park Service
(NPS), state agencies, and universities—researches, monitors, and warns about
vog hazards.13

Congress may continue to consider whether NVEWS enables HVO to monitor Hawaii’s active
volcanoes at levels commensurate with their threats to meet the system’s objective “to monitor,
warn, and protect citizens of the United States from undue and avoidable harm from volcanic
activity.”14 Congress also may consider how to address specific volcanic hazards, such as
volcanic ash, that may have a regional-to-global impact. For example, modernizing and unifying
volcano observatory monitoring systems could enable the USGS and NOAA to integrate and
improve volcanic ash and gas models, forecasts, and warnings.

Primer on Hawaii’s Active Volcanoes and Hazards
Hawaii has six active volcanoes, five of which the USGS considers threatening to people and
property (Figure 1).15 The five threatening volcanoes are Kīlauea and Mauna Loa (very high
threat), Hualālai (high threat), and Haleakalā and Mauna Kea (moderate threat). The submarine
volcano Kama‘ehuakanaloa (also known as the Lō‘ihi seamount), which lies offshore just south
of the Kīlauea volcano, is active but was not ranked by the USGS in its 2018 assessment of
threatening volcanoes in the United States.16

“National Strong Ground Motion Project,” https://earthquake.usgs.gov/monitoring/nsmp/; University of Hawaii,
“Infrasound Laboratory University of Hawaii,” https://www.isla.hawaii.edu/; EarthScope Consortium, “SAGE,”
https://www.iris.edu/hq/.
12 NOAA, “Washington Volcanic Ash Advisory Center,” https://www.ospo.noaa.gov/products/atmosphere/vaac/. For
more about monitoring Alaska volcanoes, see CRS Report R48529, Alaska’s Active Volcanoes: Federal Role in
Research, Monitoring, and Warning, by Linda R. Rowan.
13 International Volcanic Health Hazard Network (IVHHN), “Hawaii Interagency Vog Information Dashboard,”
https://vog.ivhhn.org/.
14 43 U.S.C. 31k.
15 According to HVO, Hawaii has six volcanoes that have been active (i.e., had eruptive episodes) within the past
11,000 years. USGS, “Hawaiian Volcano Observatory,” https://www.usgs.gov/observatories/hvo. See also footnote 1.
16 USGS, “Kama’ehuakanaloa,” https://www.usgs.gov/volcanoes/kama%E2%80%98ehuakanaloa. A submarine
volcano (also known as a seamount) is completely underwater and forms on the seafloor.

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Figure 1. USGS Threat Assessment of Five Active Volcanoes in Hawaii

Source: John W. Ewert et al., 2018 Update to the U.S. Geological Survey National Volcanic Threat Assessment, U.S.
Geological Survey (USGS), Scientific Investigations Report 2018-5140, 2018, https://doi.org/10.3133/sir20185140.
Map from USGS and Esri.
Notes: Triangles with different colors and sizes denote the location and threat level of five volcanoes in Hawaii
(see legend). The USGS uses 24 volcanic hazard factors, including the potential exposure of people and property,
to determine each volcano’s threat level.

The Hawaiian Islands are of volcanic origin, and each island comprises one or more volcanoes
(Figure 2).17 The island of Hawaiʻi has four threatening volcanoes (Mauna Kea, Hualālai, Mauna
Loa, and Kīlauea), and these are the youngest and most active volcanoes of the Hawaiian chain.18
The island of Maui has one active and threatening volcano, Haleakalā, which last erupted about
400 years ago and has had at least 10 documented eruptions in the past 1,000 years. The
volcanoes formed over time from the Hawaiian hot spot plume, or a plume of hot material, rising
from deep within the Earth. Heat from the Hawaiian hot spot partially melts mantle rock at depths
starting about 200-400 kilometers (125-250 miles) below Earth’s surface. This melting produces
magma that rises upward through the overlying Pacific plate. As the plate moves west-northwest,
each volcano that formed on the plate moves with it and stops growing as it moves away from the
hot spot plume.19 The age and orientation of the volcano island chain record the Pacific plate’s
direction and rate of movement over time.

17 USGS, “Evolution of Hawaiian Volcanoes,” https://www.usgs.gov/observatories/hvo/evolution-hawaiian-volcanoes.
18 USGS, “Active Volcanoes of Hawaii,” https://www.usgs.gov/observatories/hvo/active-volcanoes-hawaii.
19 The Pacific plate is moving to the west-northwest at a speed of between 7 and 11 centimeters (cm), or approximately

3-4 inches, a year. Pacific Northwest Seismic Network, “Plate Tectonics,” https://pnsn.org/outreach/about-earthquakes/
plate-tectonics.

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Figure 2. Emperor-Hawaiian Chain and Hot Spot Plume Model

Sources: Top panel: U.S. Geological Survey (USGS), Hawaiian Volcano Observatory, “Volcano Watch—
Exploring the Deep Source of Hawaiian Volcanoes,” https://www.usgs.gov/observatories/hvo/news/volcanowatch-exploring-deep-source-hawaiian-volcanoes. Bottom panel: USGS, “Geologic Investigations Map I-2800:
This Dynamic Planet,” https://pubs.usgs.gov/imap/2800/.

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Notes: Bathymetry, which is the measurement of the depth of water or the underwater equivalent of
topography, and topography in map legend given in meters. Ma = millions of years ago. The Emperor chain
consists of extinct volcanoes that are below the water surface, called seamounts. The Hawaiian chain consists of
seamounts and subaerial volcanoes (i.e., volcanoes that exist on land rather than underwater). Most of the
subaerial volcanoes are part of the Hawaiian Islands. In the upper panel, the triangles denote the approximate
location of each volcano, and the different shades of white, gray, and black denote slightly different chemical
compositions of the lava. The lower panel is a schematic cross section of the Hawaiian hot spot plume, showing
the rise of hot material from deep in the Earth and the formation of volcanoes on the Pacific plate. The Pacific
plate moves, and a new volcano begins to form over the hot spot in an assembly-line-like fashion. The plume and
plate motion form the chain of seamounts and volcanoes seen on the map in the upper panel.

Hawaiian Volcanic Risks
Hawaii’s volcanoes are categorized as shield volcanoes, and people and property near a shield
volcano face the greatest risks from lava flows, volcanic bombs, and volcanic gases (Figure 3
and Appendix B). A shield volcano forms a broad shield-shaped (i.e., greater width than height)
mountain over time from successive effusive eruptions of lava, mostly basalt, composed of
mostly low-silica magmas (Appendix B).20 As a shield volcano grows, it may accommodate its
growth (i.e., adding mass, spreading, and widening) by forming rift zones (or fissures), which are
zones of weakness where magma may flow and may erupt to the surface through fissures, cracks,
vents, craters, cones, fumaroles, and other openings (Figure 4 and Appendix B). Most eruptive
activity starts at the summit or along the rift zones of a shield volcano. Mauna Loa and Kīlauea,
the two most active Hawaiian volcanoes, feature two major rift zones each branching away from
the summit of the volcano (Figure 4).21

20 Low-silica magmas (silica is silicon dioxide, which in crystal form is the mineral quartz) tend to have less gas and be

less explosive than high-silica magmas. Low-silica lavas tend to flow slowly away from an eruptive center and form
low-silica rocks, such as basalts and andesites upon cooling (Appendix B). National Park Service (NPS), “Shield
Volcanoes,” https://www.nps.gov/articles/000/shield-volcanoes.htm; USGS, “How Big Are the Hawaiian Volcanoes?”
https://www.usgs.gov/faqs/how-big-are-hawaiian-volcanoes.
21 Kīlauea’s two rift zones are oriented parallel to its mobile southern flank, because Kīlauea is growing and is
buttressed against Mauna Loa on its northern flank. NPS, “Shield Volcanoes,” https://www.nps.gov/articles/000/shieldvolcanoes.htm.

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Figure 3. Schematic of Volcanic Hazards from Hawaii’s Shield Volcanoes

Source: National Park Service/U.S. Geological Survey, “Shield Volcanoes,” https://www.nps.gov/articles/000/
shield-volcanoes.htm.
Notes: A fully formed shield volcano has gentle slopes, is much wider than it is tall, and resembles the shape of a
shield. The schematic shows volcanic hazards, including hazards created when volcanic activity meets ocean
water. See Appendix B for a description of these hazards. Not shown are other hazards from earthquakes,
landslides, and tsunamis that are related to volcanic activity and volcanic growth.

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Figure 4.Volcanoes on the Island of Hawaiʻi

Source: National Park Service, “Shield Volcanoes,” at https://www.nps.gov/articles/000/shield-volcanoes.htm.
Notes: Map showing the topography (gray shaded relief) and bathymetry (colors, see legend) as well as the five
subaerial volcanoes and one submarine volcano (labeled) that comprise the island of Hawaiʻi. The red and orange
shaded regions on the island are individual lava flows from Kīlauea, Mauna Loa, or Hualālai volcanoes. The
approximate location of the rift zones (labeled) of Mauna Loa and Kīlauea are traced by white bands on the map.
Most eruptive activity starts at the summit or along the rift zones. Hawaiʻi Volcanoes National Park is shown by
the dark gray shaded area. The park includes the summits and parts of the rift zones of Mauna Loa and Kīlauea.
SW = southwest; NE = northeast. Thin black lines denote the boundaries of each volcano. See also U.S.
Geological Survey, “Hawaii’s Volcanoes Revealed,” https://pubs.usgs.gov/imap/2809/.

In addition to these volcanic hazards, growing and active volcanoes may cause earthquakes,
landslides, and tsunamis, which may pose a risk to people and property.22 Figure 5 shows historic
earthquakes with a magnitude 6 or greater on the island of Hawaiʻi during the 19th and 20th
centuries.23 Figure 6 shows the USGS-estimated seismic hazard for Hawaii with the estimated
22 HVO, “Hazards,” https://www.usgs.gov/observatories/hvo/science/hazards. Earthquakes, landslides, and tsunamis in

Hawaii may have other sources besides volcanic activity in Hawaii. For example, severe weather may cause a
landslide, and an earthquake in Alaska may cause a tsunami in Hawaii. Earthquakes in Hawaii may be volcanic (i.e.,
related to magma, fluid, or gas movement) or tectonic (i.e., related to ground movement along faults or landslides).
23 Magnitude refers to the size of an earthquake and is expressed in whole numbers and decimal fractions. There are
(continued...)

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exposed population density.24 Figure 7 shows some submarine landslides around Hawaii caused
by eruptions, earthquakes, or erosion.25 Some of these landslides may generate tsunamis.
Hawaii’s active volcanoes have added risks from volcanic activity that intersects with the Pacific
Ocean, such as laze plumes and tsunamis (Figure 9 and Appendix B). In Kīlauea’s recorded
history, most of the fatalities and injuries were related to a 1790 explosive eruption from
Halema‘uma‘u crater and an 1868 earthquake that generated landslides and tsunamis.26

different magnitude scales. USGS, “Earthquake Magnitude, Energy Release, and Shaking Intensity,”
https://www.usgs.gov/programs/earthquake-hazards/earthquake-magnitude-energy-release-and-shaking-intensity.
24 For more information about the USGS Earthquake Hazards Program that is responsible for U.S. Seismic Hazard
Assessments, see CRS Report R43141, The National Earthquake Hazards Reduction Program (NEHRP): Overview
and Issues for Congress, by Linda R. Rowan.
25 For more information about the USGS Landslide Hazards Program, which supports landslide research and
monitoring in the United States, see CRS Report R47588, Landslides: Federal Role in Research, Assessment, and
Response, by Linda R. Rowan.
26 USGS, HVO, “Volcano Watch: Kīlauea: Nation’s Most Deadly Volcano,” https://www.usgs.gov/news/volcano-

watch-kilauea-nations-most-deadly-volcano; USGS, HVO, “Volcano Watch: The Threat of Tsunamis,”
https://www.usgs.gov/news/volcano-watch-threat-tsunami; USGS, HVO, “Volcano Watch: Volcano Slides Are Often
the Cause of Large Earthquakes,” https://www.usgs.gov/news/volcano-watch-volcano-slides-are-often-cause-strongearthquakes.

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Figure 5. Earthquakes on the Island of Hawaiʻi with a Magnitude of 6+ During the
19th and 20st Centuries

Source: County of Hawaiʻi, Earthquake Hazards and Estimates in the County of Hawaii, February 2005,
https://www.nehrp.gov/pdf/earthquake_hazards_hawaii.pdf.
Notes: Map shows earthquakes of magnitude (M) 6.0 or larger in the 19th and 20th centuries. Dates given in
month/day/year format. All double-digit years are in the 20th century. Magnitudes and earthquake locations are
estimated for events that occurred before a seismic network was deployed to record earthquakes. Magnitudes
and locations for events observed by a seismic network are calculated based on the type of seismic instruments
in use at the time. Shaded areas show the extent of the rupture for select earthquakes. See Fred W. Klein et al.,
“Seismic Hazard in Hawaii: High Rate of Large Earthquakes and Probabilistic Ground-Motion Maps,” Bulletin of the
Seismological Society of America, vol. 91, no. 3 (June 2001), pp. 479-498 for more information about magnitude
estimates and calculations. In the 21st century, damaging ground shaking has occurred from two M 6.7+
earthquakes, one in 2006 and one in 2018; an M 5.2 earthquake on July 5, 2021; and an M 6.2 earthquake on
October 10, 2021. These 21st-century earthquakes were associated with Kīlauea volcanic activity and volcanic
growth. Data on 21st-century earthquakes from the U.S. Geological Survey, “ANSS Comprehensive Earthquake
Catalog (ComCat),” https://earthquake.usgs.gov/data/comcat/.

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Figure 6. USGS Seismic Hazard Model for Hawaii
(2021)

Source: Mark D. Petersen et al., “2021 U.S. National Seismic Hazard Model for the State of Hawaii,” Earthquake
Spectra, vol. 38, no. 2 (May 2022), pp. 865-916, https://doi.org/10.1177/87552930211052061.
Notes: Modified Mercalli Intensity VI is strong shaking that is felt by all and causes slight damage. The shaking
may be more intense, ranging from very strong (VII) to extreme (X). See USGS, “Modified Mercalli Intensity
Scale,” https://www.usgs.gov/programs/earthquake-hazards/modified-mercalli-intensity-scale. The population
density is given in number of people per square kilometer (km2).

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Figure 7. Some Submarine Landslides in Hawaii

Source: U.S. Geological Survey (USGS), “Black Dashed Lines Delineate 17 Distinct Landslides,”
https://www.usgs.gov/media/images/black-dashed-lines-delineate-17-distinct-landslides.
Notes: Black dashed lines delineate 17 distinct submarine landslides around Hawaii over the last several million
years. Bathymetry of the seafloor shown by colors ranging from pink to purple indicates the water depth around
the islands (see legend); shades of gray show land topography above sea level. Red areas on the island of Hawaiʻi
indicate lava flows from eruptions within the past 200 years. See USGS, “Evolution of Hawaiian Volcanoes,”
https://www.usgs.gov/observatories/hvo/evolution-hawaiian-volcanoes for more details about these landslides.

Kīlauea Volcano
Kīlauea is among the most active volcanoes in the world.27 Since 1952, Kīlauea has erupted
dozens of times. From 1983 to 2018, eruptive activity was nearly continuous along the volcano’s
East Rift Zone (ERZ; Figure 8).28 At the summit, Halema‘uma‘u crater within the summit caldera
hosted an active lava pond and vigorous gas plume from 2008 to 2018. In 2018, the 35 years of
continuous activity on the ERZ ended. Additional eruptions and volcanic activity at Kīlauea have
occurred over short (hours to days) to long (days to weeks) periods since 2018. Since December
23, 2024, eruptive episodes have been intermittently active within Halema‘uma‘u crater.

27 USGS, “Kīlauea,” https://www.usgs.gov/volcanoes/kilauea.
28 Also see Figure 4 and Appendix B.

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Figure 8. Lava Flows from Kīlauea Volcano, 1750 to 2018

Source: National Park Service (NPS), “Shield Volcanoes,” at https://www.nps.gov/articles/000/shieldvolcanoes.htm.
Notes: NPS modified the map and figure using data from the U.S. Geological Survey (USGS), as listed on the
figure. Lava flow hazard zones are from the USGS, “Map Showing Lava-Flow Hazard Zones, Island of Hawaii,”
https://pubs.usgs.gov/mf/1992/2193/. The hazard flow zones are approximate and gradational, not distinct as
displayed on the map.

The most recent damaging volcanic event was the 2018 Kīlauea eruption (Figure 9 and Figure
10).29 From May through August 2018, large lava flows covered land southeast of the Hawaiʻi
Volcanoes National Park (HAVO) on the easternmost part of the ERZ, destroying more than 700
homes and devastating residential areas in the Puna District (Appendix C lists some damage and
economic losses tabulated by the County of Hawaiʻi).30 There were no fatalities. Twenty-three
people were injured on a boat that was hit by a volcanic bomb during the 2018 Kīlauea eruption
(Figure 9), and a volcanic bomb from a lava flow from fissure 17 (Figure 10) reportedly caused
29 USGS, “2018 Lower East Rift Zone Eruption and Summit Collapse at Kīlauea,” https://www.usgs.gov/volcanoes/

kilauea/science/2018-lower-east-rift-zone-eruption-and-summit-collapse-kilauea.
30 Hawaii Volcanoes National Park, “Kīlauea Eruption,” https://www.nps.gov/havo/learn/nature/2018-eruption.htm.
Hawaii County, “Kīlauea Eruption,” https://recovery.hawaiicounty.gov/resources/2018-eruption#:~:text=
Summary,of%20lava%20erupted%20through%20August. Elinor S. Meredith et al., “Damage Assessment for the 2018
Lower East Rift Zone Lava Flows of Kīlauea Volcano, Hawaiʻi,” Bulletin of Volcanology, vol. 84, no. 65 (2022),
https://doi.org/10.1007/s00445-022-01568-2; Kyle R. Anderson et al., “The 2018 Eruption of Kīlauea: Insights,
Puzzles, and Opportunities for Volcano Science,” Annual Review of Earth and Planetary Sciences, vol. 52 (2023),
https://doi.org/10.1146/annurev-earth-031621-075925.

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one injury in Leilani Estates.31 In addition, the Puna Geothermal Venture’s 38 megawatt Puna
power plant, which is about 15 miles from Kīlauea’s summit and supplied about 29% of the
island’s electricity before the eruption, was shut down and damaged by the volcanic event. On
May 9, 2018, then-Governor David Ige issued an emergency declaration for the Puna power plant
to remove 60,000 gallons of pentane, a highly flammable gas used in geothermal operations.32
Operators had to shut down power generation by quenching 10 of 11 geothermal wells with
water, and they plugged one well to prevent further damage and gas releases. Lava inundated part
of the plant, covered and damaged two capped wellheads and other infrastructure, and eventually
completely surrounded the plant. Repairs were required to reaccess the plant after the eruption.33

31 Hawaii Department of Natural Resources, “07/16/18—Ocean Lava Explosion Injures 23 Passengers on Tour Boat;

State and Federal Investigation Underway,” https://dlnr.hawaii.gov/blog/2018/07/16/nr18-140/; Mark Strassman, “Man
Says Lava Bomb from Hawaii Volcano ‘Snapped’ His Leg in Half,” CBS News, May 23, 2018,
https://www.cbsnews.com/news/hawaii-kilauea-volcano-lava-bomb-injury-darryl-clinton/.
32 Hawaiʻi Groundwater and Geothermal Resources Center, “Gov. Ige: Pentane Will Be Removed from Puna
Geothermal Venture,” https://www.higp.hawaii.edu/hggrc/gov-ige-pentane-will-be-removed-from-puna-geothermalventure/.
33 Puna Geothermal Venture, “Community,” at https://punageothermalproject.com/; Ormat, “Ormat Provides an Update
on the Puna Power Plant in Hawaii Following the Kīlauea Volcanic Eruption,” https://investor.ormat.com/news-events/
news/news-details/2018/Ormat-Provides-an-Update-on-the-Puna-Power-Plant-in-Hawaii-Following-the-KilaueaVolcanic-Eruption-05ac629ba/default.aspx; U.S. Energy Information Administration, “Volcanic Lava Flows Continue
to Affect Geothermal Power Generation on Hawaii’s Big Island,” https://www.eia.gov/todayinenergy/detail.php?id=
36672.

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Figure 9.Volcanic Hazards from Kīlauea Eruptions

Sources: (a) U.S. Geological Survey (USGS), “Helicopter Overflight of Kīlauea’s LERZ on May 19, 2018, around
8:1 ...”, https://www.usgs.gov/media/images/helicopter-overflight-kilaueas-lerz-may-19-2018-around-81. (b) USGS,
Hawaiian Volcano Observatory, “Volcano Watch—New Insights Gained from Kīlauea Volcano’s 2018 Summit
Collapses,” https://www.usgs.gov/news/volcano-watch-new-insights-gained-kilauea-volcanos-2018-summitcollapses. (c) National Park Service, “September 2023 Summit Eruption,” https://www.nps.gov/havo/learn/nature/
september-2023-summit-eruption.htm. (d) Hawaii Department of Natural Resources, https://dlnr.hawaii.gov/
blog/2018/07/16/nr18-140/.
Notes: (a) Aerial photograph of lava flows emerging from the elongated fissure that damaged property and
infrastructure in the Puna District. The flow direction in this photograph is from upper center to the lower left.
Photograph taken during a helicopter overflight of Kīlauea Volcano’s lower East Rift Zone on May 19, 2018,

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around 8:18 am, Hawaii Standard Time (HST). (b) Photograph of ash that exploded from Halema‘uma‘u crater on
May 27, 2018. (c) Aerial photograph of a volcanic gas-rich plume that created damaging volcanic smog (i.e., vog)
moving away from the floor of Halema‘uma‘u crater, Kīlauea, on September 14, 2023. (d) Photograph shows
some of the damage to the metal roof of a vessel caused by a volcanic bomb. Twenty-three people on a Lava
Ocean Tours vessel were injured shortly after 6 a.m. HST on July 16, 2018, when a volcanic bomb crashed
through the metal roof of the vessel near the coast of Kīlauea volcano. See Appendix B for descriptions of
volcanic terms.

In addition to damage to communities near the volcanic activity, the 2018 eruption caused many
changes to Kīlauea volcano that may impact natural resources and land management, visitors, and
local communities. The summit area of Kīlauea was dramatically changed by tens of thousands of
earthquakes, towering ash plumes (Figure 9), and a massive collapse of the summit caldera
(Figure 11; note the Halema‘uma‘u crater is a smaller pit crater within the larger caldera,
Appendix B). According to the USGS, 13.7 square miles of land were inundated by lava (lava
thickness varies across the area, up to 30-80 feet thick in some places), 875 acres of new land
were created at the coastline (Figure 10), about 30 miles of roads were covered by lava, about 1
billion cubic yards of lava erupted (enough to fill at least 320,000 Olympic-size swimming
pools), and about 60,000 earthquakes were recorded from April 30 to August 4, 2018 (4,400 were
magnitude 3 and higher, and the largest, at magnitude 6.9, occurred on May 4, 2018).34

34 NPS/USGS, “Preliminary Summary of Kīlauea Volcano’s 2018 Lower East Rift Zone Eruption and Summit

Collapse,” https://www.nps.gov/havo/planyourvisit/upload/PrelimSum_LERZ-Summit_2018_508.pdf; USGS, HVO,
“Volcano Watch: The 2018 Eruption of Kīlauea Was Big on a Global Scale,” https://www.usgs.gov/observatories/hvo/
news/volcano-watch-2018-eruption-kilauea-was-big-global-scale.

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Figure 10. 2018 Kīlauea Eruption: Map of Part of Volcano and Lava Flows

Source: Christina A. Neal et al., “The 2018 Rift Zone Eruption and Summit Collapse of Kīlauea Volcano,”
Science, vol. 363, no. 6425 (January 2019), pp. 367-374, https://www.science.org/doi/10.1126/science.aav7046.
Notes: The light gray lines are roads, and the white irregular line on the inset map denotes the former coastline
before it was inundated with lava. The 2018 eruption created 875 acres of new land, as shown in the inset map.
The numbers pointing to black dots on the inset map denote individual fissures where eruptive activity occurred.

The 2018 eruptive events also damaged federal facilities. The USGS HVO facilities at the summit
caldera of Kīlauea volcano were damaged beyond repair (Figure 11).35 The USGS is building a
new research facility at the University of Hawaiʻi at Hilo; constructing a new field station on
Kīlauea summit in HAVO; and repairing, hardening, and adding monitoring instruments,
communications, and power to its monitoring network on Kīlauea.36 HAVO was closed to the
public on May 11, 2018, and partially reopened on September 22, 2018. NPS is still repairing
facilities and infrastructure damaged by the 2018 Kīlauea eruption within the park (Figure 12).37

35 USGS, HVO, “Volcano Watch: HVO’s Ongoing Recovery from the 2018 Kīlauea Eruption,” https://www.usgs.gov/

volcanoes/kilauea/news/volcano-watch-hvos-ongoing-recovery-2018-kilauea-eruption.
36 USGS, “2019 Disaster Relief Act: USGS Recovery Activities,” Fact Sheet 2019-3066, October 2019,
https://pubs.usgs.gov/fs/2019/3066/fs20193066.pdf.
37 NPS, “Recovery of Hawaiʻi Volcanoes National Park,” at https://www.nps.gov/havo/recovery.htm.

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Figure 11. 2018 Summit Collapse at Kīlauea Volcano

Source: Christina A. Neal et al., “The 2018 Rift Zone Eruption and Summit Collapse of Kīlauea Volcano,”
Science, vol. 363, no. 6425 (January 2019), pp. 367-374, https://www.science.org/doi/10.1126/science.aav7046.
Notes: Top: Aerial photograph of the summit caldera was taken northwest of the caldera looking to the
southeast after the collapse. Bottom: Light detection and ranging (lidar) images for digital elevation models of
Kīlauea’s summit from 2009 and from August 11, 2018, showing the collapse of the caldera. Black lines indicate
roads; the locations of the Hawaiian Volcano Observatory (HVO) facilities and former lava lake are indicated.
The red and blue lines correspond to the locations of cross sections for depth measurements. Along the red
line, the crater deepened by as much as 500 meters (about 1,640 feet).

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Figure 12. Hawaiʻi Volcanoes National Park, Kīlauea Summit Map

Source: National Park Service (NPS), “Recovery of Hawaiʻi Volcanoes National Park,” at https://www.nps.gov/
havo/recovery.htm.
Notes: Areas that remain closed indefinitely include ‘Iliahi Trail (not shown on map) and Halema‘uma‘u Trail
(partially shown on map) that use to traverse part of the caldera floor, Crater Rim Drive beyond Uēkahuna, and
the Jaggar Museum (not shown on map). NPS may update park information as conditions change. U.S. Geological
Survey, “Kīlauea Volcano Updates,” https://www.usgs.gov/volcanoes/kilauea/volcano-updates. Accessed
information and map on April 7, 2025.

Mauna Loa Volcano
Mauna Loa is among the largest and most active volcanoes on Earth.38 The volcanic mass rises 17
kilometers (about 10.5 miles) from the seafloor, and the subaerial part of the volcano is about 120
kilometers (about 74.5 miles) wide, covering roughly half the island of Hawaiʻi (Figure 4 and
Figure 13). Mauna Loa has erupted 34 times since 1843, and its volcanic hazards threaten people
and property on the island of Hawaiʻi (Figure 14). The 2022 Mauna Loa eruption caused some
damage, including to NOAA’s Mauna Loa Observatory.39 Figure 14 shows the amount of time it
may take lava flows to reach different populated areas, ranging from hours to weeks. According
to the USGS, research, monitoring, and warning to identify volcanic hazards such as lava flows
may help ensure timely response by authorities to reduce volcanic risks to people and property.40

38 USGS, “Frequently Asked Questions About Mauna Loa Volcano,” https://www.usgs.gov/volcanoes/mauna-loa/

frequently-asked-questions-about-mauna-loa-volcano#.
39 CRS Insight IN12059, Mauna Loa Eruption, by Linda R. Rowan; and USGS, “November 27–December 10, 2022
Eruption of Mauna Loa,” at https://www.usgs.gov/volcanoes/mauna-loa/science/november-27-december-10-2022eruption-mauna-loa. See also NOAA, “Global Monitoring Laboratory,” https://gml.noaa.gov/obop/mlo/.
40 USGS, Island of Hawaiʻi Interagency Operations Plan for Volcanic Eruptions, July 2024, https://www.usgs.gov/
programs/VHP/coordination-plans (hereinafter, USGS, Island of Hawaiʻi Interagency Plan, 2024).

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Figure 13. Mauna Loa Shield Volcano: Photograph and Graphic

Source: National Park Service, “Shield Volcanoes,” at https://www.nps.gov/articles/000/shield-volcanoes.htm.
Photograph by U. S. Geological Survey, “Snow Adorns the Upper 1.5 km (5,000 ft) of Mauna Loa Volcano,”
https://www.usgs.gov/media/images/snow-adorns-upper-15-km-5000-ft-mauna-loa-volcano. Graphic modified
from Rebecca H. Ashton, “A Dynamic Landscape Formed by the Power of Volcanoes” (master’s thesis, Oregon
State University, 2003).
Notes: Shield volcanoes are much wider than they are tall. Mauna Loa rises 17 kilometers (about 10.5 miles)
from the seafloor (the subaerial part of Mauna Loa rises about 13,680 feet above sea level). Mauna Loa’s base on
the seafloor is about 160 kilometers (100 miles) wide, and the subaerial part of the volcano is about 120
kilometers (about 74.5 miles) wide, covering about half of the island of Hawaiʻi. For comparison, Mount Rainier,
the tallest stratovolcano in the contiguous United States, rises about 4.3 kilometers (2.7 miles or 14,410 feet)
above sea level and is about 16 kilometers (10 miles) wide. See Appendix B for definitions of volcano types.

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Figure 14. Mauna Loa Lava Flow Hazards

Source: U.S. Geological Survey, “Geology and History of Mauna Loa,” https://www.usgs.gov/volcanoes/maunaloa/science/geology-and-history-mauna-loa.
Notes: The lava flow hazard zones displayed on the figure and listed in the legend include Zone 1(most
hazardous)—the summit and rift zones, where lava and volcanic gases have repeatedly erupted; Zone 2
(hazardous)—slopes of the volcano adjacent to the summit and rift zones, where recorded lava flows have
repeatedly flowed downslope; Zone 3 (less hazardous)—less likely to have lava flows because of greater distance
from the summit and rift zones or because the topography does not allow easy downslope flow; and Zone 6 (no
hazard)—protected from lava flows by topographic features or barriers. The dashed red circle around the
summit is the 12,000-foot elevation contour. Historic lava flows from eruptions between 1843 and 1984 are
displayed in colors, with blue-to-green shades being the oldest lava flows and yellow-to-orange shades being the
youngest lava flows during the time period. See U.S. Geological Survey, “Frequently Asked Questions and
Answers About Lava-Flow Hazards,” https://www.usgs.gov/observatories/hvo/frequently-asked-questions-andanswers-about-lava-flow-hazards, for a complete lava flow hazard map for the island of Hawaiʻi that includes
Zones 4 and 5, which cover other areas of the island but not Mauna Loa.

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National Volcano Early Warning and Monitoring
System
In 2019, Congress passed legislation that authorized a National Volcano Early Warning and
Monitoring System (NVEWS; §5001 of P.L. 116-9; 43 U.S.C. 31k).41 The law directed the USGS
to establish NVEWS to monitor volcanoes, warn U.S. citizens of volcanic activity, and protect
citizens from “undue and avoidable harm.”42 In addition, under the Robert T. Stafford Disaster
Relief and Emergency Assistance Act (42 U.S.C. §5132), the USGS may provide alerts and other
technical assistance about volcanoes using federal and other communication services to states and
civilian populations in endangered areas. The 2019 law specifies that the system’s objective is to
monitor U.S. volcanoes at a level commensurate with the volcanic threats. NVEWS has two
purposes: (1) organize, modernize, standardize, and stabilize the monitoring systems of the five
U.S. volcano observatories, and (2) unify the monitoring systems of these observatories into a
single interoperative system.43
The USGS has published various reports and plans about NVEWS. The agency submitted a fiveyear plan for establishing and managing NVEWS to Congress in 2020, annual reports to
Congress charting the progress of NVEWS from 2021 to 2024, a recommended monitoring plan
in 2024, and the Volcano Science Center Response Plan for Significant Volcanic Events in 2024.44
Through these reports and plans, the USGS has detailed updates to monitoring systems; the
establishment of a National Volcano Information System, which is expected to serve the dual
purposes of a national volcano data center and a 24/7 volcano watch office; and efforts to
establish advisory committees (pursuant to §5001 of P.L. 116-9).45
In 2022, Congress passed legislation that amended NVEWS to direct cooperation and
coordination between the USGS’s and NOAA’s volcano monitoring (§10501 of P.L. 117-263).
The law directed the Secretary of the Interior and the Secretary of Commerce to develop and
execute a memorandum of understanding to establish cooperative support for NVEWS activities
with NOAA.46 The law also directed the Secretary of Commerce to submit cost estimates for
41 For additional information about NVEWS see CRS In Focus IF11987, The National Volcano Early Warning and

Monitoring System, by Linda R. Rowan.
42 USGS, “National Volcano Early Warning System: Monitoring Volcanoes According to Their Threat,”
https://www.usgs.gov/programs/VHP/national-volcano-early-warning-system-monitoring-volcanoes-according-theirthreat.
43 43 U.S.C. 31k.
44 Peter F. Cervelli et al., Five-Year Management Plan for Establishing and Operating NVEWS: The National Volcano
Early Warning System, USGS Open-File Report 2021–1092, 2021, https://doi.org/10.3133/ofr20211092 (hereinafter
USGS, NVEWS Plan, 2021). See also Charlie Mandeville et al., The Volcano Hazards Program—Strategic Science
Plan for 2022–2026, USGS, Circular 1492, 2022, https://doi.org/10.3133/cir1492; Ashton F. Flinders et al.,
Recommended Capabilities and Instrumentation for Volcano Monitoring in the United States, USGS, Scientific
Investigations Report 2024-5062, 2024, https://doi.org/10.3133/sir20245062 (hereinafter USGS, Recommended
Monitoring, 2024); and Seth C. Moran et al., The U.S. Geological Survey Volcano Science Center Response Plan for
Significant Volcanic Events, USGS, Circular 1518, 2024, https://doi.org/10.3133/cir1518 (hereinafter USGS, Response
for Volcanic Event, 2024).
45 USGS, HVO, “Volcano Watch: A Focus on the National Volcano Information System,” https://www.usgs.gov/
observatories/hvo/news/volcano-watch-a-focus-national-volcano-information-service. Posted by the USGS on April 10,
2025. See also USGS, “National Volcano Early Warning System Advisory Committee,” https://www.usgs.gov/
programs/VHP/national-volcano-early-warning-system-advisory-committee-nvewsac.
46 A memorandum of understanding between the USGS and NOAA already exists to collaborate on activities involving
physical and biological sciences that the USGS can utilize as needed. Correspondence between CRS and USGS, March
(continued...)

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NVEWS activities at NOAA to the Secretary of the Interior to be incorporated into the NVEWS
management plan. In 2025, NOAA submitted an implementation plan with cost estimates to
Congress. The plan aims to focus on seven equal priorities to improve (1) the monitoring and
forecasting of vog; (2) operational planning to warn about debris flows/lahars; (3) the
quantification of airborne ash hazards for aviation; (4) the quantification of ashfall hazards;
(5) near-real-time data sharing; (6) the forecasting of volcanogenic tsunamis and submarine
eruptions; and (7) the efficacy of USGS and NOAA hazard information products.47

Federal Research, Monitoring, and Warning in
Hawaii
The below section summarizes USGS’s and NOAA’s roles in researching, monitoring, and
warning for Hawaii’s active volcanoes.

Hawaiian Volcano Observatory
HVO researches, monitors, forecasts, warns about, and seeks to reduce risks from volcanic
hazards in Hawaii and American Samoa (Figure 15).48 HVO was founded in 1912 and was the
first USGS volcano observatory in the United States.49 The USGS Volcano Science Center (VSC)
manages HVO. HVO also monitors, analyzes, and warns about earthquakes in Hawaii and
maintains a seismic network, the Hawaii Integrated Seismic Network (HISN), that is part of the
U.S. Advanced National Seismic System (ANSS).50
As needed, HVO may involve other USGS VSC staff from volcano observatories in Alaska
(AVO), the Cascades (CVO), California (CalVO), and Yellowstone (YVO) or other USGS offices
(Figure 15).51 HVO communicates and collaborates with international agencies involved in
volcanic hazards, including the International Civil Aviation Organization (ICAO) and the
International Volcanic Health Hazard Network (IVHHN).52 The USGS volcano observatories and
NOAA’s VAACs are contributing members of ICAO’s International Airways Volcano Watch.53
31, 2025. See also “MOU GS21000543” in USGS, “List of Memorandums of Understanding (MOUs),” updated
August 23, 2023, https://www.usgs.gov/media/files/list-memorandums-understanding-mous.
47 Kenneth E. Graham et al., Implementation Plan for the National Oceanic and Atmospheric Administration’s
Modernization of the National Volcano Early Warning and Monitoring System Pursuant to the National Defense
Authorization of Fiscal Year 2023, NOAA, 2025, pp. 1-19 (hereinafter NOAA, Implementation Plan, 2025). For more
information about debris flows see CRS Report R47588, Landslides: Federal Role in Research, Assessment, and
Response, by Linda R. Rowan and CRS Report R47618, Post-Wildfire Debris Flows: Federal Role in Assessment and
Warning, by Linda R. Rowan and Eva Lipiec.
48 HVO, “Hawaiian Volcano Observatory,” https://www.usgs.gov/observatories/hvo. The Alaska Volcano Observatory
(AVO) acts as the backup for HVO, the California Volcano Observatory, the Cascades Volcano Observatory, and the
Yellowstone Volcano Observatory. In the event that AVO is unable to serve as a backup, the Cascades Volcano
Observatory will assume this critical function. USGS, Response for Volcanic Event, 2024.
49 NPS, “The Hawaiian Volcano Observatory,” https://www.nps.gov/parkhistory/online_books/hawaii-notes/vol4-27m.htm.
50 USGS, “Advanced National Seismic System,” https://www.usgs.gov/programs/earthquake-hazards/anss-advancednational-seismic-system.
51 USGS, Response for Volcanic Event, 2024.
52 International Civil Aviation Organization (ICAO), “ICAO,” https://www.icao.int/Pages/default.aspx; and IVHHN,
“Welcome to IVHHN,” https://ivhhn.org/.
53 ICAO, Handbook on the International Airways Volcano Watch, Doc 9766-AN/968, 2024 (hereinafter ICAO,
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The USGS volcano observatories publish weekly reports on volcanic activity for U.S. volcanoes,
and the Smithsonian Institution’s Global Volcanism Program publishes weekly reports on
volcanic activity for volcanoes outside the United States to cooperating organizations and the
public.54 In particular, HVO and the Washington VAAC provide information and warnings for
Hawaii’s active volcanoes to ICAO. HVO and NOAA provide information to the Hawaii
Interagency Vog Information Dashboard in coordination with IVHHN.55

Handbook, 2024). See also Larry Mastin et al., “Progress in Protecting Air Travel from Volcanic Ash Clouds,” Bulletin
of Volcanology, vol. 84, no. 9 (2022), https://doi.org/10.1007/s00445-021-01511-x (hereinafter Mastin et al., Progress
in Protecting Air Travel).
54 Smithsonian Institution, “Global Volcanism Program,” https://volcano.si.edu/. USGS, “USGS operates five U.S.
Volcano Observatories,” https://www.usgs.gov/programs/VHP/usgs-operates-five-us-volcano-observatories. ICAO
relies on the U.S. Volcano Observatories for information about U.S. volcanoes and the Global Volcanism Program for
information on volcanoes outside of the United States and its territories. ICAO also cooperates with other volcano
observatories when there is significant volcanic activity that may require volcanic ash advisories. ICAO, Handbook,
2024.
55 International Volcanic Health Hazard Network (IVHHN),“Hawaii Interagency Vog Information Dashboard,”
https://vog.ivhhn.org/.

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Figure 15. U.S. Volcano Observatories and Areas of Responsibility

Source: Interagency Council for Advancing Meteorological Services, National Volcanic Ash Operations Plan for
Aviation, Second Release, ICM-P35-2024, December 2024, https://www.icams-portal.gov/resources/icams/
related_documents/2024_nvaopa.pdf.
Notes: The map depicts U.S. Geological Survey (USGS)-led volcano observatories and areas of responsibility.
The black boundaries on the map indicate the geographical areas of responsibility assigned to each of the five
USGS volcano observatories. The red triangles locate the 158 volcanoes within the United States and its Pacific
territories that have been active during the Holocene Epoch (11,700 years ago to the present day), plus ”three
notably large and long-lived caldera systems (Yellowstone, Wyoming; Valles, New Mexico; and Long Valley,
California).” John W. Ewert et al., 2018 Update to the U.S. Geological Survey National Volcanic Threat Assessment,
USGS, Scientific Investigations Report 2018-5140, 2018, https://doi.org/10.3133/sir20185140.

Research
HVO research is focused on understanding the processes, hazards, and risks of Hawaii’s and
American Samoa’s volcanoes. HVO employs scientists and other specialists in geology,
geophysics, seismology, volcanic gases, computer technology, geophysical instruments, and radio
systems.56 Kīlauea and Mauna Loa volcanoes on the island of Hawaiʻi are among the most active
in the world, and this activity has led to a large number of observations and research to

56 USGS, “About the Hawaiian Volcano Observatory,” https://www.usgs.gov/observatories/hvo/about-hawaiian-

volcano-observatory.

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understand volcanic processes and volcanic hazards.57 In addition, data collected from the large
number of earthquakes on the island of Hawaiʻi are used for research to understand volcanic
processes and earthquake mechanisms.58

Monitoring
HVO volcano monitoring (Figure 16) includes ground-based instruments to record and measure
earthquakes, ground movement (e.g., tilting, uplift, subsidence, movement along a fault,
landslide), lava movement, magma movement and magma volume below the surface, volcanic
gases, sound waves in the atmosphere, and visual changes in volcanic activity.59 HVO’s
monitoring networks consist of more than 100 monitoring sites with instruments, power, and
communications. Instruments may include seismometers, accelerometers, tiltmeters, Global
Navigation Satellite System (GNSS) receivers, gas instruments, infrasound, and cameras.
Monitoring sites continuously transmit data to HVO, where the data are recorded, processed, and
analyzed. Changes in volcanic activity are detected automatically, and HVO scientists are notified
immediately for further observations and analysis and for warning.
Scientists and engineers may go into the field to directly sample gases, lavas, and other volcanic
material for research, monitoring, and warning (Figure 16). Analyzing the chemical and physical
properties of volcanic materials may help scientists define hazards and better understand volcanic
processes. Scientists and specialists in the field also may survey the volcano to measure any
changes and use cameras to measure volcanic activity.
Remote-sensing from instruments on aircraft (e.g., unoccupied aircraft systems, helicopters,
planes) and satellites is used to detect, record, process, and analyze volcanic activity (Figure
16).60 HVO uses Earth observations from satellites, which may include the USGS and National
Aeronautics and Space Administration’s (NASA’s) Landsat Mission,61 NASA’s Earth Observing
System,62 NOAA’s weather satellites,63 and the European Space Agency’s Sentinel Mission,
among others.64 HVO also uses weather data from NOAA and pilot observations.65
57 Smithsonian Institution, Global Volcanism Program, “Kīlauea,” https://volcano.si.edu/volcano.cfm?vn=332010;

Global Volcanism Program, “Mauna Loa,” https://volcano.si.edu/volcano.cfm?vn=332020.
58 See for example, John D. Wilding et al., “The Magmatic Web Beneath Hawaii,” Science, vol. 379, no. 6631
(December 22, 2022), pp. 462-468, https://doi.org/10.1126/science.ade5755.
59 USGS, “Volcano Monitoring by Hawaiian Volcano Observatory,” https://www.usgs.gov/observatories/hvo/science/
volcano-monitoring-hawaiian-volcano-observatory.
60 For example, Ryan Lanclos, “Hawaii Volcano: Scientists, Emergency Responders Put Drones to Work,” Esri, Esri
Blog, August 8, 2018, at https://www.esri.com/about/newsroom/blog/hawaii-volcano-drones-responders.
61 USGS, “Landsat Missions,” https://www.usgs.gov/landsat-missions.
62 NASA, “NASA’s Earth Observing System,” https://eospso.nasa.gov/content/nasas-earth-observing-system-projectscience-office.
63 NOAA, “Satellites,” https://www.noaa.gov/satellites, and National Weather Service (NWS), “Satellites,”
https://www.weather.gov/about/satellites.
64 The European Space Agency, “The Sentinel Missions,” https://www.esa.int/Applications/Observing_the_Earth/
Copernicus/The_Sentinel_missions. See also National Academies of Sciences, Engineering, and Medicine, Volcanic
Eruptions and Their Repose, Unrest, Precursors, and Timing, 2017, pp. 1-122, https://doi.org/10.17226/24650, Table
1.2 Satellite-Borne Suite for Volcano Monitoring.
65 A Pilot Weather Report (PIREP) is an inflight weather report submitted by an aircraft pilot or crew member. An
Aircraft Report (AIREP) is also an inflight weather report provided by the pilot or derived from onboard sensors, such
as wind and temperature. PIREPs are U.S.-only reports, whereas AIREPs are worldwide. In instances where volcanic
ash is observed, pilots can report this information either in a PIREP or an AIREP. When volcanic ash details are
communicated in a PIREP, the report is termed an Urgent PIREP; in an AIREP, it is referred to as a Special AIREP.
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The 2018 Kīlauea eruption destroyed instruments and monitoring infrastructure.66 Congress
provided supplemental appropriations in FY2019 to repair some of the volcano monitoring
network and establish new HVO facilities (P.L. 116-20).67 Using those funds, HVO has replaced
some instruments and is hardening telemetry and adding new instruments.68 HVO has installed
new seismometers, higher-resolution GNSS receivers and tiltmeters, and higher-resolution image
and thermal cameras. HVO has acquired new field instruments, including a gravimeter to
measure magma movement, a laser rangefinder to measure the level of any lava lakes, and gas
sensors to measure gas compositions and concentrations. The funding also allowed HVO to
acquire high-resolution topographic maps using airborne light detection and ranging (lidar) to
measure and analyze changes (see, for example, Figure 11).69

Pilots typically complete a Volcanic Activity Report (example of the form available at Federal Aviation Administration
(FAA), Aeronautical Information Manual, https://www.faa.gov/air_traffic/publications/atpubs/aim_html/
appendix_2.html) that may contain extra details about the physical characteristics of ash clouds after concluding flight
operations or during flight debriefings. It also may function as a Special AIREP, with an additional section dedicated to
describing the ash cloud. Interagency Council for Advancing Meteorological Services (ICAMS), National Volcanic
Ash Operations Plan for Aviation, Second Release, ICM-P35-2024, December 2024, https://www.icams-portal.gov/
resources/icams/related_documents/2024_nvaopa.pdf (hereinafter ICAMS, National Volcanic Ash Operations, 2024).
66 USGS, HVO, “Volcano Watch: HVO’s Ongoing Recovery from the 2018 Kīlauea Eruption,” at
https://www.usgs.gov/volcanoes/kilauea/news/volcano-watch-hvos-ongoing-recovery-2018-kilauea-eruption.
67 USGS, “2019 Supplemental Appropriations Activities,” https://www.usgs.gov/supplemental-appropriations-fordisaster-recovery-activities/2019-supplemental-appropriations.
68 In addition to network restoration and hardening, instrument upgrades in the field and in the laboratory included new
gravimeters, seismometers, Global Positioning System/Global Navigation Satellite System, multi-gas sensors, laser
rangefinders, visual and thermal cameras, tephra/ash analyzers, optical and infrared microscopes, and unoccupied
aircraft systems.
69 For more information about lidar and related USGS topographic mapping programs, see CRS In Focus IF13079, The
3D Elevation Program (3DEP) and Its Role in Mapping Hazards and Resources, by Linda R. Rowan.

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Figure 16. Volcano Monitoring

Source: U.S. Geological Survey (USGS) Volcano Hazards Program and the Hawaiian Volcano Observatory
(HVO).
Notes: Top: USGS Infographic. USGS monitoring includes measurements of volcanic gases, ground movement
(i.e., rise, fall, or sideways movement of the surface), or vibration (i.e., shaking) related to magma movement,
earthquakes, flows or lahars, or landslides, as well as remote sensing (via camera, aircraft, and satellite
imaging/measurements) of volcanic activities. Bottom left: A USGS geologist uses a handheld laser rangefinder to
measure eruption features during the 13th episode of a 2025 Kīlauea summit eruption. USGS photograph taken
on March 11, 2025, from the western rim of Halema‘uma‘u by M. Patrick. Bottom right: A USGS geologist,
wearing protective equipment, collected a molten sample of newly erupted material in Kīlauea caldera on
September 11, 2023. The sample provided information on magma storage and transport before it was erupted
onto the surface as lava. Access to this hazardous area is by permission from, and in coordination with, Hawaiʻi
Volcanoes National Park. USGS photograph by M. Patrick. The inset shows an energy dispersive x-ray
fluorescence instrument for analysis (box on the left in the image). The computer screen shows the spectral
spikes for certain elements measured in the sample during the analysis. HVO and University of Hawaiʻi (UH),
Hilo, partners use these compositional analyses to understand the eruption. UH-Hilo photograph by S. Lundblad.

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Earthquake Monitoring and Reporting
HVO is unique among USGS volcano observatories in that it is responsible for earthquake
monitoring and reporting.70 HVO oversees the HISN, which comprises about 100 seismic sites on
the islands (about 60 of which are on the island of Hawaiʻi). HVO studies and reports on
earthquakes in various ways.71 The seismic network automatically locates earthquakes, and the
earthquake data is posted online in real time.72 HVO seismic analysts review the data, may update
the earthquake information, and post the information on the ANSS Comprehensive Earthquake
Catalog (ComCat).73 Earthquakes larger than magnitude 4 trigger a rapid response by HVO duty
seismologists and others, who are responsible for manually reviewing the earthquake and issuing
a news release within two hours.74 In addition, the National Earthquake Information Center
computes several enhanced earthquake information products, such as Did You Feel It, ShakeMap,
PAGER, and other information, that USGS and its partners use for hazard analysis and
decisionmaking.75 Anyone can sign up with the USGS to receive earthquake alerts and may tailor
the alerts for specific regions, specific magnitudes, or other parameters.76 HVO typically reports
earthquakes in volcanic activity warnings (see “Warnings” section below), because volcanic
earthquakes may track magma and lava movements and tectonic earthquakes may alter volcanic
activity. Hawaii is not part of the ShakeAlert earthquake early warning system operated by the
USGS and partners in California, Oregon, and Washington.77 A 2016 feasibility study of
earthquake early warning in Hawaii considered implementation.78

Warnings
HVO provides warnings of volcanic activity using a warning system designed by the USGS VHP
in coordination with HVO, ICAO, and the Federal Aviation Administration (FAA). The alert
system has two parts: (1) ranked terms (normal, advisory, watch, and warning) to inform people
on the ground about a volcano’s status (Figure 17) and (2) ranked colors (green, yellow, orange,
and red) to inform the aviation sector about airborne ash and gas hazards (Figure 18).

70 USGS, “Monitoring Earthquakes in Hawaii,” https://www.usgs.gov/observatories/hvo/science/monitoring-

earthquakes-hawaii.
71 USGS, “Monitoring Earthquakes in Hawaii,” https://www.usgs.gov/observatories/hvo/science/monitoringearthquakes-hawaii.
72 Earthquake data is posted in two places online, HVO homepage and the USGS Earthquakes page. Users may need to
adjust the maps on either website to see the most recent earthquakes on a Hawaiian volcano. USGS, “Hawaiian
Volcano Observatory,” https://www.usgs.gov/observatories/hvo; USGS, “Earthquake Map,”
https://earthquake.usgs.gov/earthquakes/map/?extent=7.63168,-178.1543&extent=45.95661,-106.43555.
73 USGS, “ANSS Comprehensive Earthquake Catalog (ComCat) Documentation,” https://earthquake.usgs.gov/data/
comcat/.
74 A rapid response means a duty seismologist intends to review the data within 20 minutes of receiving the data. HVO
does not operate a 24-hour-a-day (24/7) service, but the National Earthquake Information Center (NEIC) does. An
NEIC duty seismologist should provide a rapid response when HVO is closed.
75 USGS, “National Earthquake Information Center,” https://www.usgs.gov/programs/earthquake-hazards/nationalearthquake-information-center-neic. See also USGS, “Earthquakes,” https://www.usgs.gov/programs/earthquakehazards/earthquakes. NEIC acts as the national operations center of the U.S. Advanced National Seismic System.
76 USGS, “Real-Time Notifications, Feeds, and Web Services,” https://earthquake.usgs.gov/earthquakes/feed/.
77 CRS Report R47121, The ShakeAlert Earthquake Early Warning System and the Federal Role, by Linda R. Rowan.
78 Weston A. Thelen et al., Feasibility Study of Earthquake Early Warning (EEW) in Hawaii, USGS, Open-File Report
2016-1172, 2016, https://doi.org/10.3133/ofr20161172.

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Figure 17. USGS Alert-Level Terms for a Volcano

Source: U.S. Geological Survey, Island of Hawaiʻi Interagency Plan for Volcanic Eruptions, July 2024,
https://www.usgs.gov/programs/VHP/coordination-plans.

Figure 18. USGS Aviation Color Codes for Volcanic Activity

Source: U.S. Geological Survey, Island of Hawaiʻi Interagency Plan for Volcanic Eruptions, July 2024,
https://www.usgs.gov/programs/VHP/coordination-plans.

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HVO may issue a Volcano Activity Notice (VAN) and a Volcano Observatory Notice for Aviation
(VONA).
•

•

Volcano Activity Notice. A VAN is issued when a volcano’s alert level changes
(Figure 17 and Figure 18)—that is, when there is significant volcanic activity or
a significant ash resuspension event.79
Volcano Observatory Notice for Aviation. VONA is a derivative product of the
VAN that contains information in a format specifically intended for aviation users
(e.g., pilots, dispatchers, air-traffic managers, meteorologists) of volcanic hazard
information, with emphasis on ash emission. Its purpose is to communicate
volcanic activity details to the aviation sector, specifically focusing on ash-plume
information. The VONA includes an Aviation Color Code and is transmitted to
Air Route Traffic Control Centers (ARTCCs), the Honolulu Meteorological
Watch Office (MWO), and NOAA’s Washington Volcanic Ash Advisory Center
(WVAAC, located in College Park, MD, outside of Washington, DC).80

HVO may issue daily updates, weekly updates, information releases, and status reports about
Hawaii’s active volcanoes.81 In addition to these reports, HVO provides access to webcams,
photographs, videos, lava flow maps, hazards discussions, frequently asked questions, and
information about recent earthquakes. Anyone can sign up to receive notifications about volcanic
activity at U.S. monitored volcanoes through the USGS Volcano Notification Service.82
HVO follows USGS plans for distributing warnings and notices to federal, state, and local
officials as described in the Volcano Science Center Response Plan for Significant Volcanic
Events and in the Island of Hawaiʻi Interagency Operation Plan for Volcanic Eruption
(hereinafter, IH plan).83 HVO communicates with NOAA, FAA, the Department of Defense
(DOD), and NPS—among other federal, state, and local agencies—to provide observational data
and consistent interpretations and notifications of volcanic activity and hazards. HVO may
coordinate as needed with appropriate federal agencies (e.g., U.S. Fish and Wildlife Service

79 Significant volcanic activity includes elevated unrest above normal background levels or eruption (Figure 17). Ash

from previous eruptions may be resuspended in the atmosphere by strong winds and may pose a threat to people and
property. The ICAO added resuspension of ash as a type of volcanic event that may impact aviation and may be
reported in a volcanic ash advisory. Resuspension of ash is more likely from stratovolcanoes with a higher VEI that
deposit large volumes of ash around a volcano, such as stratovolcanoes in Alaska, California, Oregon, or Washington,
rather than shield volcanoes, such as shield volcanoes in Hawaii. ICAO, Handbook, 2024.
80 The Honolulu Meteorological Watch Office (MWO) falls under the purview of the Honolulu Weather Forecast
Office (WFO). NOAA, “NWS Forecast Office Honolulu, HI,” https://www.weather.gov/hfo. The United States has
three MWOs: Anchorage, AK; Honolulu, HI; and Kansas City, MO. The ICAO designates MWOs to maintain a
continuous watch over weather conditions that affect flight operations and to issue warnings and forecasts for the
aviation community. The Honolulu MWO maintains a meteorological watch over the central and western Pacific
Ocean. The Honolulu MWO is responsible for an ICAO flight information region (FIR) that covers a portion of the
Oakland Oceanic FIR south of 30 N and west of 140 W (Figure 19). ICAO, Handbook, 2024; ICAMS, National
Volcanic Ash Operations, 2024. See also NOAA, “Aviation Weather Services,” https://www.weather.gov/media/
aviation/Aviation%20trifold_without%20crop%20marks.pdf.
81 USGS, “Volcano Updates,” https://www.usgs.gov/programs/VHP/volcano-updates#hvo; and USGS, “Hawaiian
Volcano Observatory,” at https://www.usgs.gov/observatories/hvo.
82 USGS, “Volcano Notification Service (VNS),” at https://volcanoes.usgs.gov/vns2/.
83 USGS, Response for Volcanic Event, 2024; USGS, HVO, “Volcano Watch: Introducing Island of Hawaiʻi
Interagency Operations Plan for Volcanic Eruptions,” https://www.usgs.gov/observatories/hvo/news/volcano-watchintroducing-island-hawaii-interagency-operations-plan-1. The plan was completed in July 2024. USGS, Island of
Hawaiʻi Interagency Plan, 2024.

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[FWS], NPS, DOD), state agencies (e.g., state departments of natural resources), and private land
managers who have jurisdiction over the land encompassing an active or restless volcano.84
A volcanic event—defined by the USGS as any instance of heightened volcanic unrest—may
require a response scaled to the event’s magnitude.85 The USGS has developed plans to scale up
or scale down a response depending on how threatening a volcanic event is or becomes over time.
HVO issues a first response to significant changes in volcanic activity that are above normal
baseline levels for each volcano through release of VANs and VONAs to the public and to
federal, state, and local officials (Figure 17 and Figure 18).86 If a volcanic event becomes more
threatening, then HVO may scale up its response by establishing an Observatory Volcanic Event
Response Team, which monitors the volcano without interruption by establishing a 24/7 watch. If
the volcanic event becomes even more significant, the VSC Director may establish a Center
Volcanic Event Response Team.
The USGS plans also describe roles and responsibilities for USGS response team members and
consider staffing increases (using personnel from other volcano observatories or other USGS
programs) to respond to increasing levels of unrest. The plans follow the National Incident
Management System developed by the Federal Emergency Management Agency (FEMA) to
standardize command, control, and coordination of emergency responses in the United States.87 In
the event of a presidential emergency or major disaster declaration, HVO coordinates with
FEMA, as FEMA takes a lead role in the command, control, and coordination of emergency
response in these situations.88

Washington Volcanic Ash Advisory Center
NOAA’s WVAAC (located in a suburb of Washington, DC), together with HVO, studies,
monitors, forecasts, and warns about volcanic ash hazards in the atmosphere to reduce risks to
people, property, and aviation.89 WVAAC is one of nine VAACs organized by ICAO to monitor
volcanic ash around the world (Figure 19).90 A single VAAC at a time issues volcanic ash
84 USGS, Alaska Interagency Plan for Volcanic Ash Episodes, 2022.
85 A volcanic event may include a volcanic eruption (i.e., where magma reaches the surface), venting of gas or ash,

earthquakes, landslides, or any other volcanic hazard that threatens harm and damage. Although much has been learned
about volcanic activity—especially at Kīlauea, among the best-studied volcanoes in the world—no volcanic event can
be precisely predicted and any volcanic event may change, so continued and sometimes enhanced monitoring is
warranted throughout a volcanic event. USGS, Response for Volcanic Event, 2024, p. 5.
86 The USGS’s federal authority to monitor and warn about volcanic activity is codified in statute by legislation
authorizing NVEWS (§5001 of P.L. 116-9; 43 U.S.C. 31k). The law directed the USGS to establish NVEWS to
monitor volcanoes, warn U.S. citizens of volcanic activity, and protect citizens from “undue and avoidable harm.”
Under the Robert T. Stafford Disaster Relief and Emergency Assistance Act (42 U.S.C. §5132), the USGS has
authority through the President to provide alerts about volcanoes using federal and other communication services to
states and civilian populations in endangered areas.
87 USGS, Response for Volcanic Event, 2024; Federal Emergency Management Agency (FEMA), “National Incident
Management System,” https://www.fema.gov/emergency-managers/nims.
88 CRS Report R43784, FEMA’s Disaster Declaration Process: A Primer, by Bruce R. Lindsay.
89 NOAA, “Washington Volcanic Ash Advisory Center,” https://www.ospo.noaa.gov/products/atmosphere/vaac/. The
Washington Volcanic Ash Advisory Center (WVAAC) is organized within NOAA’s Office of Satellite and Product
Operations (OSPO) as part of the National Environmental Satellite Data and Information Service. OSPO has physical
offices at NOAA’s headquarters in Silver Spring, MD, WVAAC has offices in College Park, MD, and Command and
Data Acquisition Stations at Wallops Island, VA, and Fairbanks, AK. The WVAAC is named after Washington, DC.
The other U.S. VAAC is in Anchorage, AK. NOAA, “Office of Satellite and Product Operations,”
https://www.ospo.noaa.gov/.
90 ICAO, “ICAO,” https://www.icao.int/Pages/default.aspx; ICAO, Manual on Volcanic Ash, Radioactive Material,
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advisories (VAAs) for a continuous ash cloud, although two VAACs may issue simultaneous
VAAs for different ash clouds from the same volcano. As ash nears and crosses VAAC
boundaries, VAACs transfer responsibility of VAA issuance to the downstream VAAC.91 The
other U.S. VAAC is located in Anchorage, AK.92 The WVAAC serves as the backup for the
Anchorage VAAC. In addition, the U.S. Air Force 2nd Weather Squadron in the 557th Weather
Wing operates a VAAC to monitor more than 1,500 volcanoes in a 24/7 operation to monitor
eruptions that may impact DOD operations worldwide.93 The 2nd Weather Squadron VAAC serves
as a backup for the WVAAC.
Volcanic ash and gases may pose a serious risk for aircraft in flight or on the ground.94 Ash clouds
can damage aircraft in flight, such as by causing engine and avionic system failures.95 Ash can
make takeoff and landing of an aircraft treacherous and can damage aircraft on the ground,
incurring costs for cleaning, repair, or even replacement. Compared with other types of
volcanoes—such as stratovolcanoes in Alaska, California, Oregon, and Washington—Hawaiian
shield volcanoes tend to have a low volcanic explosivity index (VEI) of between 0 and 1; as a
result, Hawaiian eruptions pose less of a volcanic ash threat to aviation than eruptions from other
types of volcanoes.96 In addition, Hawaiian volcanic ash and gas eruptions generally are confined
to the area and airspace near the eruptive vent, so only aviation near a vent may be impacted.97
HVO, WVAAC, and the Honolulu MWO participate in international and national planning and
activities to address volcanic ash and gas hazards for aviation within their areas of responsibility
(Figure 19).98

and Toxic Chemical Clouds, 3rd ed., Doc 9691, AN954, 2015 (hereinafter ICAO, Manual on Volcanic Ash, 2015) and
NOAA, Implementation Plan, 2025.
91 ICAMS, National Volcanic Ash Operations, 2024.
92 NWS, “Anchorage Volcanic Ash Advisory Center,” https://www.weather.gov/vaac/.
93 Air Force, “Renewal Ensures Wing, Volcanic Ash Advisory Center Partnership Endures,” https://www.af.mil/News/
Article-Display/Article/2540260/renewal-ensures-wing-volcanic-ash-advisory-center-partnership-endures/.
94 FAA, Chapter 7-6-10, “Flight Operations in Volcanic Ash,” in Aeronautical Information Manual (AIM), September
2024, https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap7_section_6.html (hereinafter FAA, “Flight
Operations in Volcanic Ash,” 2024); ICAO, Manual on Volcanic Ash, 2015.
95 Marianne Guffanti et al., Encounters of Aircraft with Volcanic Ash Clouds: A Compilation of Known Incidents, 19532009, USGS, Data Series 545, 2010; Uta Reichardt et al., “Volcanic Ash and Aviation: Recommendations to Improve
Preparedness for Extreme Events,” Transportation Research Part A, vol. 113 (2018), pp. 101-113, https://doi.org/
10.1016/j.tra.2018.03.024 (hereinafter Reichardt et al., Volcanic Ash and Aviation, 2018).
96 VEI describes the size of explosive volcanic eruptions based on magnitude and intensity. VEI is a partially
logarithmic scale that ranges from a low explosivity of 0 to a high explosivity of 8. NPS, “Volcanic Explosivity Index
(VEI),” https://www.nps.gov/subjects/volcanoes/volcanic-explosivity-index.htm. See Smithsonian Institution’s Global
Volcanism Program, “Kīlauea,” https://volcano.si.edu/volcano.cfm?vn=332010, and Global Volcanism Program,
“Mauna Loa,” https://volcano.si.edu/volcano.cfm?vn=332020, for a list of past eruptions and their VEIs.
97 Hawaii is remote and not densely populated; nonetheless, threats to people and property are significant because
people live and work on active volcanic islands and people visit active volcanoes from the land, sea, and air. Research,
monitoring, and warning support residents, workers, and visitors with access to active volcanic islands and help
emergency responders and jurisdictional authorities prepare responses and take protective actions, such as restricting
access, when there are volcanic threats. USGS, Island of Hawaiʻi Interagency Plan, 2024.
98 ICAO, Handbook, 2024; and ICAMS, National Volcanic Ash Operations, 2024.

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Figure 19. Volcanic Ash Advisory Centers: Areas of Responsibility

Source: Congressional Research Service based on International Civil Aviation Organization (ICAO) – global
map from ICAO with an online map view available at https://store.icao.int/en/icao-volcanic-ash-advisory-centersicao-regions#mz-expanded-view-49962856382.
Notes: The National Oceanic and Atmospheric Administration (NOAA) operates the Anchorage Volcanic Ash
Advisory Center (VAAC) and the Washington VAAC (Washington, DC). These centers are responsible for
observing, measuring, and modeling volcanic ash plume distribution in the atmosphere and providing volcanic ash
advisories about volcanic hazards to aviation in the areas of responsibility shown on the map by thick red lines.
ICAO flight information regions for local to regional areas are shown by blue lines. See also National Weather
Service, “Anchorage Volcanic Ash Advisory Center,” at https://www.weather.gov/vaac/, and NOAA,
“Washington Volcanic Ash Advisory Center,” at https://www.ospo.noaa.gov/products/atmosphere/vaac/.
Airspace by country adjacent to the Anchorage and Washington VAACs shown by color shading, with each
country identified in the legend. Volcanoes shown by yellow circles from NOAA, National Centers for
Environmental Information, “Volcano Locations,” https://www.ngdc.noaa.gov/hazel/view/hazards/volcano/loc-data.

Research
Research on volcanic ash hazards in the atmosphere includes observations and modeling and
forecasting of ash and ash movement in the atmosphere. The USGS, NOAA, NASA, and
National Science Foundation support much of this research at the federal level.99 The Satellite
Analysis Branch of the National Environmental Satellite, Data, and Information Service
(NESDIS) and the NWS’s National Centers for Environmental Prediction operate WVAAC.100
The NWS operates the other NOAA VAAC, Anchorage VAAC.101 NESDIS’s mission is to
provide secure, timely global environmental data from satellites and other sources with a
component of data analysis and research. The NWS’s mission is to provide weather, climate, and
99 ICAMS, National Volcanic Ash Operations, 2024 and NOAA, Implementation Plan, 2025.
100 NOAA, “National Environmental Satellite, Data, and Information Service,” https://www.nesdis.noaa.gov/; NOAA,

“Airlines, Observatories, and Others Keep Tabs on Volcanic Activity with VOLCAT,” https://www.nesdis.noaa.gov/
news/airlines-observatories-and-others-keep-tabs-volcanic-activity-volcat.
101 NWS, “Anchorage Volcanic Ash Advisory Center,” https://www.weather.gov/vaac/.

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water data, forecasts, warnings, and other decision-support information.102 Given the different
missions of NESDIS and the NWS, it is not clear if the Anchorage VAAC and WVAAC are
integrated in their approach to research for volcanic ash warnings or if the WVAAC is responsible
for research and data analysis for volcanic ash warning products. The ICAO lists additional
research and monitoring programs from NOAA, NASA, USGS, and other organizations that help
support the VAACs’ monitoring of ash and gas (Appendix D).103

Satellite Observations
Higher spatial- and temporal-resolution observations by satellites support research and have led to
more accurate ash and gas detection and tracking to enhance forecast modeling and allow for
more timely forecasts of ash and gas movement and dispersion, compared with past forecasts.
Current geostationary satellites have roughly doubled the spatial resolution (0.5-3 kilometers;
about 0.3-2 miles) and image repeat times (< 1 to 15 minutes) compared with satellites in orbit
more than 10 years ago. Whereas satellites imaged the 1991 Pinatubo ash cloud once per hour
and the 2010 Eyjafjallajökull ash cloud once every 15 minutes, 2021 eruptions at Soufrière, St.
Vincent, were imaged once per minute. As of 2022, every VAAC may access high-quality images
at least every 15 minutes and several volcanic arcs were routinely imaged every 2.5 or
5 minutes.104
The NESDIS Center for Satellite Application and Research is responsible for developing satellite
products that support VAAC operations. The NESDIS Volcanic Cloud Analysis Toolkit,
developed by the Cooperative Institute for Meteorological Satellite Studies, is a widely used suite
of satellite-based products and services comprising, but not limited to, eruption alerts, automated
ash detection and tracking, automated gas detection and tracking, ash cloud top height, ash
loading, and imagery.105

Models
NOAA and the USGS have different models (HYSPLIT and Ash3d, respectively) to forecast ash
movement, the size of ash clouds and plumes, and ash concentrations.106 NOAA’s VAACs use the
HYSPLIT model to prepare VAAs and volcanic ash graphics (see “Warning”). P.L. 117-263
directs the U.S. volcano observatories to integrate relevant capacities of NOAA, including the
VAACs, to observe and model volcanic activity in the atmosphere and ocean. NOAA and USGS
models are adding quantitative ash concentrations to their probability forecasts, a feature the
ICAO requires from VAACs by the next decade.107

99 NWS, “The National Weather Service,” https://www.weather.gov/about/.
103 ICAO, Handbook, 2024.
104 Mastin et al., Progress in Protecting Air Travel.
105 Cooperative Institute for Meteorological Satellite Studies (CIMSS), “Volcanic Cloud Monitoring—NOAA/CIMSS,”

https://volcano.ssec.wisc.edu/; CIMSS, “Cooperative Institute for Meteorological Satellite Studies,”
https://cimss.ssec.wisc.edu/. See also Michael J. Pavlonis et al., “Automated Detection of Explosive Volcanic Eruptions
Using Satellite-Derived Cloud Vertical Growth Rates,” Earth and Space Science, vol. 5 (2018), pp. 843-980,
https://doi.org/10.1029/2018EA000410. See also NOAA, Implementation Plan, 2025, for a description of how NOAA
uses and plans to use the Volcanic Ash Cloud Analysis Tool to modernize NVEWS.
106 NOAA, “HYSPLIT Volcanic Ash Model,” https://www.arl.noaa.gov/hysplit/volcanic-ash-model/ and USGS,
“Ash3d,” https://vsc-ash.wr.usgs.gov/ash3d-gui/#!/ .
107 For example, Alice Crawford et al., “Evaluation and Bias Correction of Probabilistic Volcanic Ash Forecasts,”
Atmospheric Chemistry and Physics, vol. 22, no. 21 (2022), pp. 13967-13996, https://doi.org/10.5194/acp-22-139672022. See also ICAMS, National Volcanic Ash Operations and NOAA, Implementation Plan, 2025.

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Quantitative Ash Concentration
The ICAO is asking VAACs to develop a quantitative volcanic ash product (QVA) that provides
forecast probabilities of ash concentration at aircraft altitudes or quantifies the concentration of
ash with height, enabling aircraft operators to move away from traditional criteria for visible (to
the human eye) or discernable (by satellite) volcanic ash aloft.108 NOAA intends to begin issuing
QVAs by November 2025.109 Since the 2010 Eyjafjallajökull eruption, the ICAO and the
European Union Aviation Safety Agency have developed new procedures for aviation to deal with
volcanic ash hazards in Europe. These procedures allow aircraft operators to consider flying
through ash concentrations that pose a low risk to aircraft based on the operator’s risk
assessment.110 Studies of the 2010 Eyjafjallajökull eruption in Iceland and others have led to
advances in volcanic ash measurements, models, and forecasts.111 In Western Europe and parts of
the North Atlantic regions, the responsibility for volcanic ash avoidance or the decision to fly (or
not to fly) into an area of known or forecast volcanic ash contamination was transferred from air
traffic management to commercial aircraft operators.112 Aircraft operators must have safety risk
assessments that include decisions about flight operations in known or forecast volcanic ash.113

Monitoring
WVAAC uses observations, measurements, and forecasts from the USGS, NOAA, and other
volcano observatories to forecast, advise, and monitor the movement of volcanic ash in
WVAAC’s assigned airspace (Figure 19). WVAAC is staffed 24/7 to provide guidance and
support to Honolulu’s MWO, other MWOs, and the aviation community.114 Duty meteorologists
or satellite analysts continuously monitor remote sensing data, pilot reports, and volcano
observatories’ VANs and VONAs. WVAAC is tasked with running ash dispersion models,
determining the current and forecast area extent of the ash, and producing ash warnings. WVAAC
can request a HYSPLIT model run whenever necessary by contacting the senior duty
meteorologist and providing essential details, such as the eruption’s start time, duration, and

108 ICAMS, National Volcanic Ash Operations, 2024.
109 NOAA, Implementation Plan, 2025. FAA issued letters to NOAA instructing both U.S. VAACs to be compliant

with QVA product issuance by November 26, 2026. In addition, the NWS issued a notice about other changes in VAAs
from NOAA’s VAACs, such as providing information only in imperial measurements (i.e., feet) and removing the
aviation color code. Kevin Stone, Service Change Notice 25-43, NWS, NOUS41 KWBC 211610 PNSWSH, May 21,
2025, https://www.weather.gov/media/notification/pdf_2025/scn25-43_vaa_changes.pdf.
110 European Union Aviation Safety Agency (EASA), Flight in Airspace with Contamination of Volcanic Ash, Safety
Information Bulletin (SIB) 2023-13, December 19, 2023, https://ad.easa.europa.eu/ad/2023-13 (hereinafter EASA,
Flight in Volcanic Ash); ICAO, Volcanic Ash Contingency Plan, European and North Atlantic Regions, EUR Doc 019,
NAT Doc 006, Part II, Edition 2.2.0, 2024 (hereinafter ICAO, Volcanic Ash European and North Atlantic); Reichardt
et al., “Volcanic Ash and Aviation.”
111 The eruption released ash into the atmosphere for 39 days. Frances M. Beckett et al., “Atmospheric Dispersion
Modelling at the London VAAC: A Review of Developments Since the 2010 Eyjafjallajökull Volcano Ash Cloud,”
Atmosphere vol. 11, no. 4 (2020), pp. 352-378, https://doi.org/10.3390/atmos11040352; Reichardt et al., “Volcanic Ash
and Aviation”; Mastin et al., Progress in Protecting Air Travel.
112 EASA, Flight in Volcanic Ash; ICAO, Volcanic Ash European and North Atlantic; Frances Beckett et al.,
“Conducting Volcanic Ash Cloud Exercises: Practising Forecast Evaluation Procedures and the Pull-Through of
Scientific Advice to the London VAAC,” Bulletin of Volcanology, vol. 86, no. 63 (2024), https://doi.org/10.1007/
s00445-024-01717-9.
113 EASA, Flight in Volcanic Ash; ICAO, Volcanic Ash European and North Atlantic.
114 ICAMS, National Volcanic Ash Operations, 2024.

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eruption height. For Hawaii’s active volcanoes, WVAAC works closely with HVO and the
Honolulu MWO. WVAAC also serves as a backup for the Anchorage VAAC and other VAACs.115

Warning
WVAAC may issue a VAA with a volcanic ash graphic.116
•

•

Volcanic Ash Advisory. A VAA provides information about the presence or
anticipated occurrence of volcanic ash that could impact the safety of aircraft
operations. These advisories include details such as the volcano’s identification,
eruption time, observed position of the ash cloud, and forecast position of the
ash. In cases where the ash cloud is crossing into another VAAC’s area of
responsibility, the VAA also includes hand-off information.
Volcanic Ash Graphic. A volcanic ash graphic provides information from the
VAA in a graphical format (Figure 20).117

115 ICAO, Handbook, 2024. See also CRS Report R48529, Alaska’s Active Volcanoes: Federal Role in Research,

Monitoring, and Warning, by Linda R. Rowan.
116 ICAMS, National Volcanic Ash Operations, 2024.
117 ICAO specified the format for consistency. ICAMS, National Volcanic Ash Operations, 2024.

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Figure 20. Example of a Volcanic Ash Graphic from NOAA’s
Washington Volcanic Ash Advisory Center
(Kīlauea eruption on May 13, 2018)

Source: Volcanic Ash Advisory for Kīlauea Volcano, issued on May 13, 2018, National Oceanic and Atmospheric
Administration (NOAA), “Washington Volcanic Ash Advisory Center Archive,” https://www.ospo.noaa.gov/
VAAC/ARCH18/KILA/2018E131934.html.
Notes: The volcanic ash graphic was prepared by the Washington Volcanic Ash Advisory Center. Each panel
shows the forecast extent of the ash cloud in 6-hour increments. Top left is the eruption, top right is 6 hours
later, bottom left is 12 hours later, and bottom right is 18 hours later. Small triangle marks the summit of
Kīlauea. Hachured polygon denotes the forecasted extent of the ash cloud.

Hawaii Interagency Vog Information Dashboard
The Hawaii Interagency Vog Information Dashboard provides information about air quality and
about hazards from volcanic gas and ash or particles on the island of Hawaiʻi. The dashboard is a
partnership between the IVHHN, the Hawaiʻi County Civil Defense Agency (HCCDA), HVO,
HAVO, NOAA, the U.S. Department of Agriculture’s Farm Service Agency, the County of
Hawaiʻi, the Hawaii State Department of Health, and the Center for the Study of Active
Volcanoes at the University of Hawaiʻi, Hilo. The dashboard provides real-time information about
air quality, sulfur dioxide concentration, particles concentration, and vog in the atmosphere, as
well as forecasts for the spread of vog and other volcanic gas and ash hazards. NOAA may update

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national weather prediction models to incorporate sulfur dioxide emissions and volcanic ash and
may incorporate vog in National Air Quality Forecast Capability.118

Island of Hawaiʻi Interagency Operation Plan for
Volcanic Eruption
On the island of Hawaiʻi, the IH plan was developed to improve coordination between HVO;
HCCDA, representing the County of Hawaiʻi (i.e., entire island of Hawaiʻi); and HAVO.119 HVO
has no jurisdictional authority and is responsible only for informing jurisdictional authorities
about volcanic activity, earthquakes, and related hazards. HCCDA’s mission is to protect the
community from natural and human-made hazards; to strengthen resiliency; and to direct,
coordinate, and administrate emergency preparedness and response in Hawaiʻi County.120
HCCDA has jurisdictional authority over Hawaiʻi County, with the exception of federal lands
(Figure 21).
HAVO’s mission is to protect, study, and provide access to Kīlauea and Mauna Loa and to
perpetuate endemic Hawaiian ecosystems and the traditional Hawaiian culture connected to these
landscapes.121 HAVO develops and implements plans to protect staff, visitors, and incident
responders from incident hazards. Within the park, HAVO is responsible for responding to and
stabilizing from incident hazards; monitoring air quality; managing aircraft and vehicles in
restricted areas; implementing restricted areas, closures, and evacuations on park lands; managing
vehicular traffic; and ensuring safe viewing areas of volcanic activity.122
The current IH plan does not include other agencies with some jurisdictional authority on the
island of Hawaiʻi, such as FWS (Hakalau Forest National Wildlife Refuge); DOD (U.S. Army
Pōhakuloa Training Area); or the State of Hawaii (Figure 21).123 The current plan also does not
discuss how to cooperate with NOAA facilities on the island of Hawaiʻi, including the Mauna
Loa Observatory near the summit of Mauna Loa and the NWS office at Hilo airport.124
State and federal emergency responses to volcanic events on the island of Hawaiʻi follow the
principles of the Incident Command System (ICS) of the National Incident Management
System.125 HCCDA directs response actions and operates an ICS. The State of Hawaii provides
resources to the County of Hawaiʻi to support emergency response. If the state issues a disaster
118 NOAA, Implementation Plan, 2025.
119 USGS, Island of Hawaiʻi Interagency Operation Plan for Volcanic Eruption, 2024.
120 Hawaiʻi County Civil Defense Agency, “Hawaii County Civil Defense Agency,” at https://hawaii-county-civil-

defense-agency-hawaiicountygis.hub.arcgis.com/.
121 NPS, Foundation Document: Hawaiʻi Volcanoes National Park, January 2017, p. 5, https://www.nps.gov/havo/
learn/management/upload/HAVO_FD_SP_508.pdf. Other NPS lands on the Island of Hawaiʻi were not included in
version one of the Island of Hawaiʻi Interagency Operation Plan for Volcanic Eruption (IH plan). Puʻuhonua o
Hōnaunau National Historical Park could be inundated by lava flows from Mauna Loa, and Kaloko-Honokōhau
National Historical Park could be inundated by lava flows from Hualālai. The Ala Kahakai National Historic Trail
could be affected by lava flows from Kīlauea, Mauna Loa, Hualālai, or Mauna Kea.
122 Two segments of Highway 11 cross Hawaiʻi Volcanoes National Park (HAVO). The land is owned by HAVO, and
the state operates Highway 11 under an easement arrangement. When volcanic activity affects multiple jurisdictions,
the IH plan calls for a unified command approach.
123 USGS, Island of Hawaiʻi Interagency Operation Plan for Volcanic Eruption, 2024.
124 NOAA, “About Mauna Loa Observatory,” https://gml.noaa.gov/obop/mlo/aboutus/aboutus.html.
125 USGS, Island of Hawaiʻi Interagency Operation Plan for Volcanic Eruption, 2024. See also FEMA, “National
Incident Management System,” https://www.fema.gov/emergency-managers/nims.

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proclamation, the Hawaii Emergency Management Agency (HIEMA) and other state
departments, such as Hawaii Army National Guard, provide additional support to the ICS. If the
President issues an emergency or major disaster declaration, FEMA provides support to the state
and county ICS.126 The IH plan also describes a single jurisdictional authority response under an
ICS and a multi-jurisdictional authority response under a unified area command. In addition, if
the volcanic event is of potentially significant local, regional, or national interest, then a Joint
Information Center may be established to coordinate and facilitate public information from
agencies.
Emergency response to volcanic events on the island of Hawaiʻi may require airspace
coordination, as described in the IH plan.127 Aircraft face volcanic risks from ash, gases, volcanic
ejecta, and heat (thermal effects) from lava flows. In general, HAVO or HCCDA requests a
temporary flight restriction (TFR) from the FAA upon the start of an eruption within HAVO lands
or on state lands, respectively.128 A TFR is a regulatory action issued by FAA via a notice to air
missions (NOTAM). FAA makes the decision about any TFR, regardless of whether HAVO or
HCCDA has requested a TFR. In the past, the FAA’s Honolulu Control Facility has allowed a
TFR only in a circle shape. According to the IH plan, the Honolulu FAA may allow a polygon
shape in the future.129 The TFR generally restricts air tours, non-air tour aircraft (including charter
and personal aircraft), and media flights near an eruption to avoid volcanic hazards and air-traffic
congestion. Authorized administrative aircraft must be approved by the jurisdictional agency
within the TFR and may include HVO, County of Hawaiʻi Fire Department, Civil Air Patrol, U.S.
Coast Guard (USCG), National Guard, DOD, HAVO, FWS, state landowners, and private
landowners.
Emergency response to volcanic events on the island of Hawaiʻi may require coordination on
ocean activities, which has been handled separately by the USCG. The potential hazards of
volcanic activity affecting the ocean may include plumes of hot, corrosive seawater with
hydrochloric acid and ash particles; explosions of debris and eruptions of scalding water from hot
rock entering the ocean; sudden lava delta collapses; and waves associated with explosions and
collapses.130 The USCG established a permanent safety zone surrounding the area of lava entry
from Kīlauea volcano into the Pacific Ocean on the southeast side of the island of Hawaiʻi as of
May 11, 2018.131 The regulation prohibits persons and vessels from being in the safety zone
during active lava flow reaching the Pacific Ocean on Kīlauea volcano’s southeast coast unless
specifically authorized by the Captain of the Port of Honolulu or a designated representative.
126 FEMA, “How a Disaster Gets Declared,” https://www.fema.gov/disaster/how-declared.
127 The FAA, DOD, Hawaiʻi Army National Guard, and other aviation partners were not involved in the development

of the IH plan. However, it is anticipated that these agencies will be involved in future versions of the plan. USGS,
Island of Hawaii Interagency Operation Plan for Volcanic Eruption, 2024.
128 USGS, Island of Hawaii Interagency Operation Plan for Volcanic Eruption, 2024; FAA, “Section 2. Temporary
Flight Restrictions in the Vicinity of Disaster/Hazard Areas (14 C.F.R. Section 91.137),” https://www.faa.gov/
air_traffic/publications/atpubs/foa_html/chap20_section_2.html.
129 A polygon shape may more accurately depict the shape and forecast area of an ash plume moving away from an
eruptive vent as described by a VAAC (e.g., see Figure 20) and may allow air traffic to more effectively avoid ash in
the atmosphere. USGS, Island of Hawaiʻi Interagency Operation Plan for Volcanic Eruption, 2024; FAA, “Section 2.
Temporary Flight Restrictions in the Vicinity of Disaster/Hazard Areas (14 C.F.R. Section 91.137),”
https://www.faa.gov/air_traffic/publications/atpubs/foa_html/chap20_section_2.html.
130 USGS, “Kīlauea Volcano Erupts,” https://www.usgs.gov/news/featured-story/kilauea-volcano-erupts.
131 USCG, “Safety Zone; Pacific Ocean, Kīlauea Lava Flow Ocean Entry on Southeast Side of Island of Hawaii, HI,”
83 Federal Register 21876, May 11, 2018, https://www.federalregister.gov/documents/2018/05/11/2018-10049/safetyzone-pacific-ocean-kilauea-lava-flow-ocean-entry-on-southeast-side-of-island-of-hawaii-hi. According to the Federal
Register notice, ocean safety concerns began on December 31, 2016, when a lava delta collapsed into the ocean and
then additional volcanic activity along the southeast coast generated volcanic hazards.

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Research and monitoring by HVO of previous eruptions and the 2018 Kīlauea eruption
contributed to the USCG decision to extend the zone for 300 meters (984 feet) from the coastline.
At HAVO’s recommendation, the USCG made the safety zone flexible based on the location
where lava may be entering the ocean.
On July 16, 2018, a Lava Ocean Tours boat was hit by a volcanic bomb that injured 23
passengers.132 The boat was about 50 meters (164 feet) from the coast where lava from the 2018
Kīlauea eruption was entering the ocean. The USCG had granted permission to the tour boat
company, as well as other commercial operators, to come as close as 50 meters to the lava’s ocean
entry point. After the accident, the USCG rescinded all exemptions to the permanent 300-meter
safety zone.

132 Allison Schaefers, “Tour Boat Operator Involved in a Lava Bomb Incident Has History of Passenger Issues,” Star

Advertiser, July 18, 2018, https://www.staradvertiser.com/2018/07/18/hawaii-news/tour-boat-operator-involved-in-alava-bomb-incident-has-history-of-passenger-issues/.

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Figure 21. Island of Hawaiʻi: Land Management

Source: U.S. Geological Survey, Island of Hawaiʻi Interagency Operation Plan for Volcanic Eruption, July 12, 2024.
https://www.usgs.gov/observatories/hvo/news/volcano-watch-introducing-island-hawaii-interagency-operationsplan-1.
Notes: DLNR = Department of Land and Natural Resources; DHHL = Department of Hawaiian Homelands;
OHA = Office of Hawaiian Affairs. The U.S. Army operates the Pōhakuloa Training Area. Kohala volcano (north
of Mauna Kea volcano) is not indicated on this map; other volcanoes are labeled with larger text. Two cities are
labeled with smaller text. See Figure 4 for all five volcanoes.

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Other Volcano Warning Products in Use in Hawaii
The information and warnings from the USGS (HVO) and NOAA (WVAAC), the two primary
federal agencies focused on volcanic activity, are used to develop other volcano warning products
used in Hawaii (Table 1). In addition to the VAA warning products from WVAAC, the NWS may
issue other volcano warning products in Hawaii (Table 1). For aviation, the Honolulu MWO may
issue Significant Meteorological Information, which serves as the primary warning product to the
aviation community for volcanic ash.133 Central Weather Service Unit (CWSU) meteorologists
provide decision support and weather briefing services for 21 FAA Air Route Traffic Control
Centers (ARTCCs).134 CWSU meteorologists, typically located at the Honolulu ARTCC, may
issue a Center Weather Advisory or Meteorological Impact Statement as needed, to provide
additional information essential to air traffic managers’ decisionmaking processes about volcanic
ash.
The Honolulu Weather Forecast Office (WFO) may issue ashfall statements, advisories, and
warnings for the public and marine communities (Table 1). Ashfall is included in Terminal
Aerodrome Forecasts as appropriate. The WFOs also assist in the coordination of information
during volcanic events by soliciting ashfall reports and briefing local community members and
leadership about potential hazards.
In the United States, the FAA advises pilots not to fly through volcanic ash and provides advice
about flight operations if a pilot encounters ash while flying, landing, or taking off.135 The FAA
may restrict air space based on the presence of volcanic ash.136 The FAA may issue a NOTAM
about volcanic ash hazards; it also may issue an Urgent Pilot Report or a TFR (Table 1).137 DOD
and Hawaii state and county agencies issue other volcano warning products (Table 1).
Table 1. Island of Hawaiʻi: Volcanic Warning Products and Authorities
Organization
Hawaiian Volcano Observatory

Product and/or Authorities
Information release
Weekly update
Daily update
Status report
Volcano Activity Notice (VAN)
Volcano Observatory Notice for Aviation (VONA)

133 The Honolulu MWO falls under the purview of the Honolulu WFO. NWS, “NWS Forecast Office Honolulu, HI,”

https://www.weather.gov/hfo. The Honolulu MWO maintains a meteorological watch over the central and western
Pacific Ocean. The Honolulu MWO is responsible for an ICAO FIR that covers a portion of the Oakland Oceanic FIR
south of 30 N and west of 140 W (Figure 19). ICAO, Handbook, 2024; ICAMS, National Volcanic Ash Operations,
2024. See also NOAA, “Aviation Weather Services,” https://www.weather.gov/media/aviation/
Aviation%20trifold_without%20crop%20marks.pdf.
134 FAA, “Air Route Traffic Control Centers (ARTCC),” https://www.faa.gov/about/office_org/headquarters_offices/
ato/service_units/air_traffic_services/artcc.
135 FAA, “Flight Operations in Volcanic Ash.”
136 FAA, “3-5-3 Temporary Flight Restrictions,” in Aeronautical Information Manual (AIM), at https://www.faa.gov/
air_traffic/publications/atpubs/aim_html/chap3_section_5.html.
137 A notice to air missions (NOTAM) prescribes direction used to format and distribute information regarding
unanticipated or temporary changes to services, components of, or hazards in the National Airspace System. FAA,
“Notice to Air Missions (NOTAM),” https://www.faa.gov/documentLibrary/media/Order/7930.2S_Chg_2_dtd_12-221.pdf.

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Organization

Product and/or Authorities

Washington Volcanic Ash Advisory Center

Volcanic Ash Advisory (VAA) and Volcanic Ash Graphic
(VAG)

Hawaii Interagency Vog Information Dashboard

Vog measurements and forecasts
Air quality measurements, advisories, or guidance
statements

National Weather Service

Significant Meteorological Information (SIGMET)—
Honolulu Meteorological Watch Office (MWO)
Meteorological Impact Statement (MIS)—Honolulu
Central Weather Service Unit
Center Weather Advisory (CWA)—Honolulu Central
Weather Service U

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/crs%3AR48622. Public record. Not legal advice.