PUYALLUP TRIBE ALL HAZARD MITIGATION PLAN
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SUB-SECTION 4G.5
PUYALLUP TRIBE ALL HAZARD MITIGATION PLAN
VOLCANIC HAZARD1
Table of Contents
TABLE OF CONTENTS ...............................................................................................1
IDENTIFICATION DESCRIPTION ................................................................................2
DEFINITION .............................................................................................................2
PROFILE ...................................................................................................................5
LOCATION AND EXTENT ...............................................................................................5
PLANNING AREA ...................................................................................................... 16
THE OCCURRENCES .................................................................................................. 16
IMPACTS ............................................................................................................... 18
VULNERABILITY TO PLANNING AREA....................................................................... 30
LAHAR FLOWS ......................................................................................................... 32
TEPHRA ................................................................................................................ 33
RESOURCE DIRECTORY .......................................................................................... 34
REGIONAL ............................................................................................................. 34
NATIONAL ............................................................................................................. 34
ENDNOTES ............................................................................................................. 35
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Identification Description
Definition2
A volcano is a vent in the earth’s crust through which molten rock (lava), rock fragments, gases,
and/or ash can be ejected from the earth’s interior (see Figure 4.5-1). Volcanic hazards in the
region include all hazards associated with individual volcanoes in the Cascade Mountain Range.
This includes tephra, landslides, lahars, pyroclastic flows, lava, and acid rain, see Figure 4.5-1.
Figure 4.5-1 Volcanic Hazards3
Volcanoes have a number of hazards that have to be considered in any mitigation plan. Many of these
will only affect areas close to the volcano, but others like lahars and tephra, can cause damage many
miles away.
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Non-magmatic Volcanic Hazards
Figure 4.5-2 Debris flow at
Tahoma Creek, July 26, 1988
Debris Flows
Debris flows of glacial ice and rock debris may be set in
motion by explosions, earthquakes, and heat-induced melting
of ice and snow, or the sudden release of water held within a
glacier called a glacial outburst flood. A debris flow is a type
of landslide that moves at high speeds; see Figure 4.5-2
Debris flow at Tahoma Creek, July 26, 1988.4 The best recent
examples of this are the small debris flows that come off the
mountain every few years. The October 2-3, 1947 glacial
outburst flood was the largest debris flow since Mt. Rainier
National Park was established5. Most debris flows at Mt.
Rainier are confined to areas either within the park or in a
few instances extending to areas just outside the park
boundary.
Lahars
Also called mudflows, lahars are a specific type of debris
flow associated with volcanoes. They are dense mixtures of
water-saturated debris that move down-valley, looking and
behaving much like flowing concrete. They involve much
greater quantities of material than do the normal debris flows
and can cover many square miles of valley bottom with mud
and other debris many meters deep, see Figure 4.5-3. 6 A
contractor examines a large Douglas fir stump, which had
been buried 20 feet below the valley floor in Orting after the
Electron lahar. Over 60 postglacial (since the last ice age)
lahars have been identified as coming from Mt. Rainier.7
4.5-3 Douglas Fir Stump – Electron
Lahar Deposit in Orting
Lahars come in two types, called cohesive and non-cohesive
lahars.8 Cohesive lahars consist of debris with at least three to
five percent clay content. The clay content in a cohesive lahar
allows the lahar to resist losing material and transforming from
a lahar to a hyper-concentrated stream flow. As such, a
cohesive lahar will tend to maintain its integrity as a flow,
constant in texture and coherent as a mass over greater
distances than does a non-cohesive flow.
Non-cohesive lahars contain less than three to five percent
clay, usually around one percent. These lahars tend to be more
granular and consist of relatively unaltered volcaniclastic
debris. As the flow moves away from the volcano, it tends to deposit material, become diluted
and eventually become a hyper-concentrated flow. Essentially the fluid within the flow outruns
the sediment, leaving it behind as deposits of rock, gravel, sand, etc.
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Toxic Gases
Pockets or clouds of toxic gases may develop on or near both active and inactive volcanoes.
Their chemical poisons can cause internal and external burns, or asphyxiation through oxygen
starvation. Carbon dioxide, an example of an asphyxiant, is heavier than air and when given off
by a volcano can collect in low-lying areas. Carbon dioxide has been collected within the summit
caves of Mt. Rainier and a small area of release near Longmire has collected in small depressions
in the past and proven hazardous to mice and insects. Other gases that may be present include
sulfur compounds, carbon monoxide, chlorine, fluorine, boron, ammonia and various other
compounds. With the exception of inside the summit caves these generally are dissipated rapidly
by wind.9
Figure 4.5-4 Landslide from Little Tahoma Peak
covering Emmons Glacier
Landslide
Landslides from the sides of the volcano may be large
or small, but all can have effects on valleys down
stream. Small landslides are common on Mt. Rainier.
Large landslides occur occasionally; the last large one
was from Little Tahoma Peak, a subsidiary peak on
the side of Mt. Rainier in 1963; see Figure 4.5-4.10
Depending on the size of the slide and the consistency
and temperature of the material, some of them may
transform into lahars.
Magmatic Volcanic Hazards
Volcanic Earthquakes
Often centered within or beneath the volcano,
volcanic earthquakes are usually one of three kinds:
pre-eruption earthquakes caused by explosions of
steam or underground magma movements; eruption
earthquakes caused by explosions and collapse of
walls inside the volcano, and post-eruption
earthquakes caused by the retreat of magma, interior
structural collapse and landslides of material from the
crater walls and sides of developing domes.
Lava flows
Lava flows are masses of hot, partially molten to molten rock that flow down slope, generally
following valleys. Lava flows from the Cascade volcanoes tend to be short and slow moving due
to their high viscosity. The viscosity of lava flows is more dependent on the chemical
composition of the material rather than the temperature. Mt. Rainier lava flows have high silica
content and tend to be more viscous than do those with low silica content. As such they tend to
stay close to the volcano rather than extending down valleys long distances. Many of the Mt.
Rainier lava flows in prehistoric times tended to flow down valleys, frequently beside glaciers.
These flows now form many of the ridges that surround Mt. Rainier.
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Tephra
Table 4.5-1 Tephra Types and Sizes
Tephra is the general term now used by
Tephra Types and Sizes11
volcanologists for airborne volcanic ejecta of any
Fine Ash
<1/16 mm
size. Table 4.5-1 identifies tephra types and
Coarse ash
1/16 mm – 2 mm
related sizes.
Lapilli
2 – 64 mm
Blocks and Bombs
>64 mm
Pyroclastic Flows and Surges
Pyroclastic flows and surges can occur during explosive eruptions. Pyroclastic flows are
avalanches of hot ash, rock fragments, and gas that move at high speeds down the sides of a
volcano during explosive eruptions or when the edge of a thick, viscous lava flow or dome
breaks apart or collapses. Such flows can be as hot as 800 degrees Celsius, and are capable of
burning and destroying everything in their paths. Pyroclastic surges are more energetic and thus
less restricted by topography.
Lateral blasts
Lateral blasts are explosive events in which energy is directed horizontally instead of vertically
from a volcano. These blasts are gas-charged, hot mixtures of rock and ash that are expelled at
speeds up to 650 mph. Lateral blasts vary in size, but large ones are fairly rare.
Profile
Location and Extent12
All of Pierce County is directly and indirectly affected by volcanic hazards. Map 4.5-1 shows the
lahar, pyroclastic flow and lava hazard areas in Pierce County and Map 4.5-2 shows the potential
for tephra distribution.
As illustrated on the first map, the lahar hazard covers a great deal of the County as each of the
major river valleys comprises a portion of the lahar run out zone. USGS volcanologists and
Washington Department of Natural Resources (DNR) geologists identify Mt. Rainier as being in
an active eruptive window. From the magnitude of past events, they surmise that the
consequences of a lahar or debris flow down the populated river valleys will be catastrophic and
could potentially result in a tremendous loss of life and property. Over 150,000 inhabitants of the
river valleys work and reside on the deposits of prehistoric and historic debris flows.
The area covered by a Case I or Case II lahar (See page 7.) will include some of the larger
population centers, as well as major transportation routes, both rail and road. These areas include
the industrial and economic base for the County - the Port of Tacoma. Even though much of the
County will not be directly impacted by a lahar, it affects all of Pierce County, through
transportation changes, population redistribution, infrastructure damage, loss of income and tax
base, etc.
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Map 4.5-1 Lahars, Lava Flows, and Pyroclastic Hazards of Mt. Rainier13
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Lahars are categorized by both cohesiveness and size. According to best available science, Case
M, I, II, and III lahars are outlined below by their recurrence intervals: 14
Case M Lahars—the largest lahar to occur in the past 10,000 years is the Osceola
Mudflow. It formed about 5,600 years ago when a massive debris avalanche of weak,
chemically altered rock transformed into a lahar. Osceola deposits cover an area of about
212 square miles in the Puget Sound lowland, extending at least as far as Kent and to
Commencement Bay in Tacoma. The communities of Orting, Buckley, Sumner,
Puyallup, Enumclaw, and Auburn are wholly or partly located on top of deposits of the
Osceola Mudflow. This lahar is at least 10 times larger than any other known lahar from
Mount Rainier. Geologists believe flows of this magnitude occur far less frequently than
once every 1,000 years.
Case I Lahars—cohesive lahars originate as enormous avalanches of weak, chemically
altered rock from the volcano. They can occur with or without eruptive activity. Most
Case I flows have reached some part of the Puget Sound lowland. The Electron Mudflow
reached the lowland about 600 years ago along the Puyallup River. Its deposits at Orting
are as much as 18 feet thick and contain remnants of an old-growth forest. Average
recurrence rate for Case I lahars on Mt. Rainier is about 500 to 1,000 years.
Case II Lahars—Usually relatively large non-cohesive lahars, most commonly are
caused by melting of snow and glacier ice by hot rock fragments during eruption, but
which can also have a non-eruptive origin. More than a dozen lahars of this type have
occurred in the past 6,000 years. A few have reached the Puget Sound lowland, including
the National Lahar, which occurred about 2,000 years ago. It inundated the Nisqually
River valley to depths of 30 to 120 feet and flowed all the way to Puget Sound. About
1,200 years ago, another lahar filled valleys of both forks of the White River to depths of
60 to 90 feet, and flowed 60 miles to Auburn. The average time interval between Case II
lahars from Mt. Rainier is near the lower end of the 100 to 500 year range.
Case III Lahars—this class of flows includes small debris avalanches as well as debris
flows triggered by sudden, unpredictable release of water stored by glaciers. These debris
flows are largely restricted to the slopes of the volcano, rarely moving beyond the
National Park boundary; since 1926, outburst floods destroyed or damaged bridges,
roads, and national park visitor facilities on about 10 occasions. Glacial outburst floods
are unrelated to volcanic activity and typically coincide with periods of unusually high
temperatures or unusually heavy rain in summer or early autumn. About three dozen such
flows occurred during the 20th century. Case III lahars occur at an average time interval
at Mt. Rainier of about 1 to 100 year
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Table 4.5-2 Estimated Lahar Travel Times for Lahars 107 to108 Cubic Meters in Volume
(Approaching a Case I Lahar in Size)15 is based on information from geologists at the Cascade
Volcano Observatory. It gives a
Table 4.5-2 Estimated Lahar Travel Times for Lahars 107
more detailed overview of the
to108 Cubic Meters in Volume
lahar hazard from Mt. Rainier.
Estimated Travel
River Basin
Dr. Tom Pierson of the Cascade
Time in hours
Volcano Observatory, at the
Carbon River
Carbonado
0.2
request of Pierce County,
Wilkeson
0.3
developed some travel time
Orting
0.7
estimates for the various rivers
Puyallup River
leading from the volcano. For
Orting
0.7
the Puyallup and Carbon they
Sumner
1.1
are based on the time it takes for
Puyallup
1.3
the lahar to travel from the point
Commencement Bay
1.8
Nisqually River*
where the lahars are recognized
Alder Lake
1.0
by the monitors that are part of
La
Grande
1.5
the lahar warning system in
Haggedorn Road & 526th St
2.0
those valleys. Because they
White River**
have no lahar warning system,
Greenwater
<1
estimates on the White and
Mud Mt. Dam overtopping
ca. 2
Travel times on the Puyallup and Carbon Rivers are from Dr. Pierson and are based on
Nisqually Rivers are from the
the time it would take for the lahar to travel from the lahar recognition points, These are
actual release of material from
monitors that will pick up a seismic signal from the lahar and broadcast it to the State
and County. Travel times on the Nisqually and White Rivers are from the Pierce County
the volcano’s edifice.
cartography work of Karen Truman.
*The Nisqually River lahar entering Alder and La Grande Lakes will displace the water
column, pushing it over their tops, therefore travel times downstream from the dams will
more closely follow the time patterns of a catastrophic flood.
**The White River has the Mud Mountain Flood Control Dam on it that can work very
well at containing a Case II lahar and most of a Case I lahar. This is why all times below
the dam are assumed to be 2 hours or greater. It is dependent on the amount of water
behind the dam. It is empty most of the year.
New studies show that the
process of hydrothermal
alteration is unevenly
weakening the inside of Mt.
Rainier. This is a process
whereby the interior portions of the mountain are being chemically altered by contact with hot,
acidic water. This makes the slopes more susceptible for failure, increasing both the possibility
and size of lahars. The slopes above the Puyallup River drainage are weaker than those above
other river drainages originating from Mt. Rainier. The potential risk is compounded by the fact
that more people live and work in this river valley than other Mt. Rainier drainage areas.
The other volcanic hazard that might directly affect the County is the potential for tephra, from
an eruption, to cover portions of the County. Mt. Rainier has a long history of tephra eruptions.
Early lava flows that may precede the development of Mt. Rainier appear to date from no earlier
than 2.9 million years ago.
The volcanic cone built up gradually from a sequence of flows that were apparently frequent.
Chemical composition of many of the flows shows them to be composed of andesite, with some
marginally dacite.16 Given this type of rock combined with the evidence of tephra and breccia, it
appears that many of Rainier’s eruptions distributed ash over significant areas. An extremely
large deposit appears in the record somewhere between 30,000 and 100,000 years ago. This
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eruption was apparently on the scale of the Mt. St. Helens eruption of 1980 and it is estimated
that the volume of ash erupted was around 1 km3.There have been no further eruptions of this
size in Holocene times.
Map 4.5-2 Ashfall Probability from Mt. Rainier
The potential then for an
actual deposition of ash
itself from Mt. Rainier is
relatively small over much
of the County, see Map
4.5-217 which includes the
probability of a major
tephra eruption from the
volcano impacting
County.
Another possibility is that
Pierce County could be
affected by tephra from
other volcanoes in the
Cascade chain. This
probability, while
possible, is also very
small; see Map 4.5-3.18
Besides Mt. Rainier, Mt.
St. Helens has the highest
probability of distributing
ash across Pierce County. Map 4.5-3 Annual Probability of 10 Centimeters or more of
For any of the volcanoes to Tephra Accumulation in the Pacific Northwest
do so, including Mt.
Rainier, the wind needs to
be coming from the right
direction.
Throughout the Pacific
Northwest, most of the
normal wind patterns tend
to blow from south,
southwest, or west. This
takes the tephra away
from the populated areas
of the County. It should
be noted that during the
1980 eruptions of Mt. St.
Helens, most of Pierce
County received some
ash, although never a
great quantity.
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Map 4.5-4 Puyallup Tribe of Indians Lahar Hazard Area
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Map 4.5-5 Puyallup Tribe of Indians Port of Tacoma Lahar Hazard Area
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Map 4.5-6 Puyallup Tribe of Indians Downtown Lahar Hazard Area
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Map 4.5-7 Puyallup Tribe of Indians Fife/Puyallup Lahar Hazard Area
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Map 4.5-8 Puyallup Tribe of Indians Kapowsin Lahar Hazard Area
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Map 4.5-9 Puyallup Tribe of Indians Orting/Wilkeson Lahar Hazard Area
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Planning Area
The volcano hazard impacts 100% of the Planning Area. Tephra directly affects the entire the
planning area and lahars directly affect the Puyallup River Valley. Lahars also impact those areas
that are not in the lahar path because of the impact on resources, displaced populations,
transportation routes, etc. Map 4.5-4 shows the lahar hazard areas for the entire Planning Area
and Map 4.5-5 through Map 4.5-9 are scaled down to show specific Tribal parcel lands at risk for
lahar flows. This detail will allow for specific mitigation planning efforts. The portions of the
Planning Area located on the plateau are not directly affected by the lahar. Those parts of the
Planning Area whose elevation is out of the inundation zone will, however, be impacted by
secondary impacts resulting from the lahar, such as evacuations of valley populations, and
impacts to natural resources. A much further in depth discussion outlining the Planning Area’s
vulnerability to the volcanic hazards is discussed under the Vulnerability Section.
The Occurrences
Figure 4.5-5 Cascade Eruptions gives a good idea of how frequently the Cascade volcanoes have
erupted in relation to each other.19 As can be seen, while Mt. St. Helens has been the most active
over the past 4,000 years, many other volcanoes, albeit not all of them, have also been active
during this period, including Mt.
Rainier. While the chart does cover
Figure 4.5-5 Cascade Eruptions
many of the volcanoes in the
Cascades, it is not inclusive. It
ignores the British Columbia
volcanoes like Mount Garibaldi and
Meager Mountain. The area of the
Cascade Range with the most
volcanoes is Oregon. In addition to
those listed on the chart, Oregon has
a number of others that could erupt
and deposit ash throughout the
Pacific Northwest. They include,
amongst others, Mount Bachelor,
Broken Top, Belknap, Mount
McLoughlin, Mount Bailey,
Diamond Peak and Mount Thielsen.
During the past 10,000 years there
have been 11 identified tephra
eruptions, from Mt. Rainier, ranging in size from 0.001 to 0.3 km3.20 See Table 4.5-3, Mt.
Rainier Identified Tephras from the last 10,000 years.21 Notice that none of them begins to come
close to the magnitude of ash deposited from the Mt. Saint Helens eruption of 1980.22 The St.
Helens eruption of 1980 deposited approximately 1.01 cubic kilometers of material or a little
over three times the amount from the largest Rainier eruption shown on the table.
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As can also be seen from the table the
last eruption putting out tephra was
around 150 years ago. Mt. Rainier
however, had a few small eruptions
throughout the 1800s. The record23
shows minor eruptions about 1820(?),
1841 through 1843(?), 1854 (?), 1879
and 1882.
Table 4.5-3 Mt. Rainier Identified Tephra, last
10,000 Years
Table 4.5-4 provides a list of past
occurrences of debris flows on the
various river valleys in Pierce County.
Table 4.5-4 Pierce County River Valley Debris Flow History
PUYALLUP RIVER DEBRIS FLOW HISTORY
TYPE OF FLOW
Electron Mudflow
Lahar
Round Pass Mudflow
Lahar runout
“Pre-Y” Lahar
Lahar runout
AGE OR DATE
530-550 BP*
~ 1000 BP*
~2,600 BP*
< 3400 BP*
< 3500 BP*
>3500 BP*
AREA REACHED
Puget Sound Lowland, possibly to Puget Sound
Puget Sound Lowland
Probably to the Puget Sound Lowland
Puget Sound Lowland
Puget Sound Lowland
Puget Sound Lowland
NISQUALLY RIVER DEBRIS FLOW HISTORY
TYPE OF FLOW
Kautz Glacier/Van Trump Creek
Debris Flows
Outburst flow on Kautz Creek
AGE OR DATE
Tahoma Lahar
Post 1480 AD
Lahar runout
Lahar runout
National Lahar
Round Pass Mudflow
Lahar runout
Large lahar runout
Paradise Lahar
< 2500 BP*
< 2500 BP*
~ 2200 BP*
~ 2,600 BP*
< 3400 BP*
< 3400 BP*
4,500-5,000 BP*
August 2001
1947 AD
AREA REACHED
Near the Park boundary
Below confluence with Nisqually River
Below the confluence of Tahoma Creek & the
Nisqually River
At least to Elbe
At least to Elbe
Puget Sound
At least to National
At least to Ashford
Probably to Puget Sound Lowland
At least to Elbe
WHITE RIVER (INCLUDING WEST FORK) DEBRIS FLOW HISTORY
TYPE OF FLOW
Debris Avalanche
Gravel-rich flow
At least one lahar
Lahar in West Fork
Lahar (TBD)
Many lahars
At least 5 lahars
Osceola Mudflow
Greenwater Lahar
AGE OR DATE
1963
~ 1550 AD
> 1480 AD
< 2200 BP*
< 2200 BP*
< 2200 BP*
< 4500 BP*
~ 5000 BP*
~ 5000 BP*
AREA REACHED
Within 1 km of the White River Campground
At least to Mud Mountain Reservoir
At least 5-10 miles outside of Park boundary
At least to confluence of forks
Probably to Puget Sound
Probably to Puget Sound
Probably to edge of Puget Sound Lowland
Puget Sound Lowland
Puget Sound Lowland
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CARBON RIVER DEBRIS FLOW HISTORY
TYPE OF FLOW
Lahar runout
Lahar runout
AGE OR DATE
Post 1480 AD
Pre 1480 AD
AREA REACHED
At least 5 km below end of glacier
8-10 km beyond end of glacier
*Carbon 14 years before present, working from a base line of 1950
Recurrence Rate
While Mt. Rainier had a few small steam or very small tephra eruptions during the 1800s, these
were not eruptions to cause concern. The same can be said about the small mudflows down
Tahoma Creek over the past 40 years, or even the larger Kautz mudflow of 1947. The geologic
history of the volcano, as shown in the above tables, shows 11 volcanic tephra eruptions over the
past 9,000 years. In addition, the history of lahars in the valleys shows their time frames to be
variable with some long periods, occasionally over 1,000 years, between them. Research from
USGS scientists and others points to an annual probability of 1 in 500 to 1,000 for a significant
landslide driven lahar. In addition, the “(A)nnual probability of eruption-triggered lahars is
basically the same as the eruption probability because most eruptions will create lahars of some
magnitude –1 in 100 to 500, but probably more toward the 500 end.”24 Taking all this into
consideration, it is estimated the recurrence rate for damaging volcanic activity, be it a damaging
tephra eruption or a lahar coming down a valley, to be a 500 to 1,000 year occurrence.
Impacts
Impacts discussed here will cover ashfall or tephra, pyroclastic flows and lahar damage. Unless
stated otherwise, lahar damage will be based on the potential for a Case I lahar traveling down
the various valleys from Mt. Rainier. It will be assumed that general impacts are the same across
the four main valleys (Carbon, Puyallup, Nisqually, and White) unless stated otherwise. Impacts
from a lahar descending the Cowlitz River, the other river with its headwaters on Mt. Rainier and
located partially in Pierce County, will have no direct effect on the County once it has exited the
Park into Lewis County. There will be no further discussion of it.
Most of the impacts from a lahar will be determined by the volume of the lahar and which valley
or valleys it descends. Next is whether there is a recognizable sequence of volcanic events
leading up to its initiation. Whether it is a spontaneous lahar or the result of other developing
volcanic convulsions leading to, or part of, an eruption will have a major impact on the response
and the recovery. Other contributing factors include the time of day, time of year, and the clay
consistency of the mud.
For the purposes of this section we will assume an Electron size and type flow and for most
impacts look at the difference between the two basic scenarios of an eruption or magmatic
triggered lahar and a spontaneous lahar.
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Health and Safety of Persons in the Affected Area at the Time of the
Incident
Tephra
As mentioned above most of the tephra or ash from a volcanic eruption of Mt. Rainier should
leave western Washington and be deposited east of the Cascades. However the wind patterns
may not always blow in that direction. If not, then ash could be deposited over portions of Pierce
County. If so, a number of problems will arise.
Thick depositions of ash can collapse buildings. This is especially true if it is raining. A one-inch
layer of ash weighs between five and ten pounds per square foot. This weight can increase
dramatically with rain, because ash will hold the water. The weight can increase to 10 to 15 lbs
per square foot, leading to collapse in some cases.25 Persons inside those buildings have a
significant chance of being killed or at least injured by the collapsing structure.
Persons located in areas with falling ash can experience eye, nose and throat problems. Patients
with bronchitis, emphysema and asthma are at even greater risk. Breathing similar material in
mines and quarries by workers can lead to silicosis over many years. Short term breathing of
small quantities of ash particles is not known to cause long-term problems. The decrease in
visibility and increase in darkness in those areas heavily impacted by the tephra will disrupt
outdoor activities and in some cases cause psychological distress.
Thin ash layers can make roads slick leading to an increase in accidents. It can also clog up air
intake systems for automobiles and destroy the engine rendering the car useless for evacuation if
necessary.
Pyroclastic Flows
Pyroclastic flows by their nature will cause extensive death and injury to people in the areas
inundated by them. In Pierce County, this is restricted to those in close proximity to the volcano.
Park service personnel and tourists in the impacted area will have a very low chance of survival;
however pyroclastic flows will not extend very far beyond the boundaries of Mt. Rainier
National Park. Any citizens or park personnel in the vicinity of a pyroclastic flow will experience
the devastating impact and heat created by the flowing hot ash and rock with the usual result
being death, or if surviving, then major burns and or partial asphyxiation.
Lahars
A lahar coming down one or more valleys from Mt. Rainier has the potential to cause the highest
number of fatalities and casualties of any hazard treated in this risk assessment. The difference in
the impact on the population will be highly dependent on whether the lahar was a result of
increasing volcanic activity or is due to the spontaneous collapse of a portion of the mountain.
Lahars can be devastating in their consequences. The lahar that inundated the town of Armero in
Columbia on November 13, 1985 was relatively small compared to some of the ones that have
descended Mt. Rainier. The lahar, from the volcano Nevado del Ruiz, killed over 23,000 people
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and injured about 5,000 people.26 In this case the main wave of mud that demolished the town
ranged in depth from 6.5 to 16 feet. There could be a similar percentage of injured and killed in a
lahar from Mt. Rainier. The method of destruction, burying entire communities in a flow of
dense mud does not allow most people caught in it a chance of survival.
Magmatic or Eruption Triggered Lahar
The normal situation for lahars from most volcanoes is for there to be some warning that a lahar
is possible due to an increase in volcanic activity. With a lahar that begins when the volcano
enters an eruptive stage, there will usually be many hours, if not days or weeks of increasing
volcanic unrest. During this time, the citizens that live in the valley areas surrounding the
mountain will be put on a high alert that a lahar is possible. Memories of Mt. St. Helens and the
lahar from it should inspire people in the valleys close to the volcano to prepare to evacuate or
even self evacuate early in the eruption process. The more distant from the volcano they live or
work, the less preparation there will be overall, even for those who are directly in the path.
As the situation deteriorates, monitoring of the volcano will increase. Any needed warnings from
the State, the County, or the Cascades Volcano Observatory will be broadcast to inform and
warn residents in the potential paths to prepare for and evacuate, if able, well before any lahar is
created. Having a percentage of the people leave the valleys early allows a quicker evacuation
when it becomes necessary.
Much of the response for an early evacuation will depend on the perceived security of property
left behind. If local government does not provide adequate security, many people will not leave
their property behind, but will rather gamble that they can get out in time if necessary. For those
who did leave early, the perception that there is a lack of security for their property will bring
them back. The other factor that will bring people back is if the volcano does not erupt or send
down a lahar over time. People’s patience will rapidly wear thin and they will want to move back
home.
Overall though, having knowledge ahead of time that the volcano is coming back to life and that
a lahar could happen at any time will allow many people to get themselves and many of their
belongings out of harms way before the mud arrives. This could save many lives and a great deal
of personal belongings and property.
Spontaneous Lahar
A spontaneous lahar is most likely to happen due to the collapse of a portion of the headwall
above the Puyallup Glacier on the west flank of Mt. Rainier. The Mt. Rainier Lahar Warning
System composed of sensors to detect the lahar, and radio transmitters to send that information
back to Pierce County and Washington State warning points is in place to help prevent a lahar
coming down either the Puyallup or Carbon Rivers from taking the communities by surprise.
Having a warning system in place does not mean that everyone will be able to evacuate the
valley bottoms in time. The short time between the warning and the inundation of homes,
schools, roads and businesses will not allow the entire population to escape. In the upper valley
south of the confluence of the Puyallup and Carbon Rivers there could be many fatalities.
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A large spontaneous lahar in either the White or Nisqually Rivers would also create an instant
problem. Neither of these valleys has a lahar warning system. Having no warning system in
either of those valleys, citizens living, working, or recreating close to the mountain in the upper
valleys may have only the sound of the lahar coming down the valley to warn them. This would
not allow enough time for many of those people to evacuate. Once it has become known to
response agencies that a lahar is descending either of these valleys they will be able to put out a
notification that might reach people further downstream to allow evacuation. This would be
accomplished through use of a telephone notification system that is able to send an informational
phone call to each phone in the respective valleys. At the same time an Emergency Alert System
message can go out over radio, TV, and all hazard radio addressing the need to evacuate the
valleys.
The one good point about both of these valleys is that they have dams. If either is empty, as is
Mud Mt. Dam most of the year, or low, as Alder Dam frequently is, they could contain much of
a large lahar thereby lessening the damage and casualties further downstream.
Health and Safety of Personnel Responding to the Incident
Tephra
As pointed out above, thick depositions of tephra can collapse buildings, especially if it is
raining. Persons inside those buildings have a significant chance of being killed or at least
injured by the collapsing structure.
Responders may wind up working for long periods of time in areas with ash. The problems of
eye, nose and throat irritation could impact their ability to work in those conditions. It is not
known if this has long-term, negative health consequences.
Personnel responding to incidents will find that thin ash layers can make roads slick leading to an
increase in accidents. Emergency equipment will break and ash can clog up air intake systems
and destroy engines for rescue vehicles like helicopters, fixed wing aircraft and automobiles.
This is not just a maintenance problem. It could lead to crashes of response vehicles.
Pyroclastic Flows
Any responders in the vicinity of a pyroclastic flow will experience the same devastating impact
and heat that citizens would, with the same results, probable death, or major burns and/or partial
asphyxiation. Those responders attempting a rescue or body recovery will potentially be working
in a hot environment, with lots of ash and the potential for further pyroclastic flows that could
engulf their position.
Lahars
Because of the enormity of the event, initial response to a lahar will be limited to saving response
resources and assisting citizens to get to high ground, all while attempting to keep themselves
safe. What will be a problem for the safety and health of responders is that the lahar will leave
citizens stranded at various places throughout the valley. They could be on buildings that did not
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collapse or in trees that were not knocked down or highway overpasses. Essentially, people could
be on any structure, tall enough to be above the mud and strong enough to survive being
inundated by it. Since the mud will in many cases be too deep to drive or walk through directly,
helicopter rescues might be necessary. This has all the dangers inherent in that type of operation.
In addition hazardous chemicals and sewage will contaminate some areas rendering them
hazardous to anyone working there. There is also the possibility of more mud flows inundating
the valley floor. A contributing factor is rain. Rain could pick up more of the material left in the
higher parts of the valley and transport it down to the lower valley and deposit it as a new layer
on the earlier flow.
During the initial build up to an eruption, when the Cascade Volcanoes Observatory warns about
an upcoming event and warns citizens that they might want to evacuate, all local police forces
will be put in the position of controlling access to those areas deemed hazardous. This could
include both the Nisqually and Puyallup Valleys. Irate citizens, demanding access to their
properties could create hazardous situations for these forces. There could be attempts to push
through barricades, threats to officers or others staffing those barricades, or even if the area is
shut down for a long period of time, riots.
After a major lahar responders from public works and utilities will not be able to do any initial
work in the lahar zone to restore the damaged area. The lahar will totally block access to the area
and will have taken out the utilities and roads; in effect the entire surface infrastructure. Utilities
that were underground to begin with, like pipelines, may be buried under the mud but may still
be operational. As the mud solidifies over time, public works and utility providers may be able to
work back out into the devastated areas. As they do so they will have to be aware of any hazards
that might still be in the environment.
Magmatic or Eruption Triggered Lahar
With the knowledge that the volcano is threatening to erupt, first responders will be able to move
critical equipment to high ground well ahead of time. Since the public will know what is
happening as the volcano awakens and, in some cases, self evacuate ahead of time, the problems
relating to a spontaneous mass evacuation will diminish. Barricades and police services will be
in position ahead of time to conduct evacuees rapidly out of the valleys should a lahar start.
Close monitoring of the mountain should give the warning points quicker notification when a
lahar does begin. The number of people needing assistance should decrease. This should
decrease the number of technical rescues that will need to be done once the lahar has finished
moving through the valleys. Problems could be compounded if there is a lot of tephra due to the
eruption at the same time.
Spontaneous Lahar
With a spontaneous lahar, any responders in the affected valleys will be in the same position as
other citizens. They will have to get themselves and any vital equipment to high ground as
quickly as possible. In those areas some distance away from the volcano, like Fife and Puyallup,
there should be enough time for a few first responders to assist with the evacuations of some
citizens. In those areas closer to the volcano like Orting, that will be out of the question. It is
possible that when a spontaneous lahar sets off the volcanic warning system or one is heard
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coming down either the White or Nisqually rivers that the ensuing panic could by itself injure,
kill or trap in the lahar zone, those who would normally respond.
Continuity of Operations
Tephra
Small tephra explosions should not have an effect on the continuity of operations for
jurisdictions or agencies in the County unless the wind patterns are perfect for dropping it
directly on their service area.
Large tephra eruptions are different. Due to the amount of material dropped on an area,
operations can be strained. Damage to communications equipment, roofs of buildings collapsing,
roads closed, etc. can all limit the ability of an agency to maintain day-to-day operations. If the
volcano has a large tephra eruption and conditions are right to deposit the ash across portions of
Pierce County, there could be difficulty finding alternate facilities, getting staff to work and
having necessary equipment in operational shape.
However, the probability that this will be the case is relatively low. As mentioned above, Mt.
Rainier’s eruptions tend to have low quantities of tephra and when an eruption does occur the
normal wind directions over Pierce County should distribute it to eastern Washington. While
possible, it is unlikely that tephra, by itself, will dramatically alter or limit the continuity of
operations for agencies within Pierce County.
Pyroclastic Flows
Pyroclastic flows, by themselves, should not have any affect on the continuity of operations for
jurisdictions throughout the County. Rather, the effects will come from their impact on the
glaciers and snow fields located on the mountain. Their melting, from the hot rock, ash and gas
flowing across their surface, could create massive lahars in the valleys below.
Lahars
Any major lahar coming down one or more of the valleys radiating from Mt. Rainier will
dramatically alter the continuity of operations for local jurisdictions. However, depending on the
level of preparedness and whether a lahar is the result of the buildup of volcanic activity or of a
spontaneous sector collapse the continuity of operations for a jurisdiction or agency could be
very different.
Magmatic or Eruption Triggered Lahar
Lahars triggered by a buildup and release of volcanic energy will have a lead in time, ranging
from hours to weeks, for jurisdictions and agencies to prepare for the likelihood that a lahar may
be forthcoming. Those entities with infrastructure in the path of the flow will be able to find
alternate work sites and move at least some equipment to high ground out of the path. For those
entities that are only partially within the lahar path this should work well. Even if the lahar does
take out some of their infrastructure and property they should still be able to maintain an
operational posture, albeit reduced, for the rest of their jurisdiction or clients.
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For those entities entirely, or nearly entirely, within confines of the flow, things will probably be
different. Even if they were able to initially remove equipment from the valley floor and protect
all staff, normal day-to-day operations will be non-existent. With no citizens no tax base, no
offices, no infrastructure and no community, there is no continuity of operations.
Spontaneous Lahar
For spontaneous lahars the impacts to the valleys, while identical, could have a different impact
on the agencies and jurisdictions located there. Those that have operations located in the valley
that are unable to get an alternate site from which to operate will have all the problems of those
jurisdictions and agencies who have a warning but also many others. In addition they may lose
records, staff and equipment when the lahar overwhelms the valley. The possibility of
maintaining operational continuity in this scenario is impossible.
Those that have their operations run from outside the lahar inundation zone should be able to
maintain operational continuity, albeit in a possibility reduced capacity.
Delivery of Services
Delivery of services will be nonexistent in those areas of the County that are deeply buried by a
lahar. With no homes, no businesses, and no infrastructure, there will not even be a reason to
attempt delivery of services into the impacted area. Delivery of services into other areas will
depend directly on the infrastructure that is left after the lahar has inundated the valley, combined
with how much of the jurisdictions’ or agencies’ resources have been salvaged. If the lahar has
destroyed one or more of the exits from Pierce County across the Puyallup and or Nisqually
Rivers, then the ability to receive outside assistance will be delayed possibility for days. Resupply of equipment, equipment parts, food, or any of the necessities of life will be difficult.
A lahar inundating the Puyallup Valley will cut the eastern part of the County from the rest.
Bonney Lake, Buckley, Cascadia, the East Hill of Sumner and others would have to go through
King County for assistance. Delivery of services to those areas from local agencies within these
areas would go on, although some might be reduced.
There can however be some differences between the delivery of services after a magmatic
generated lahar and a spontaneous lahar.
Magmatic or Eruption Triggered Lahar
Just as with the continuity of operations, the disruption to the delivery of services would be
reduced with an eruption generated lahar. The ability to get supplies stockpiled ahead of time,
get equipment out of the lahar zone, set up sheltering system for thousands of people and
develop immediate contingency plans will all assist with the delivery of services to those areas
not destroyed by the lahar.
Spontaneous Lahar
A worst case scenario would include a lahar that begins with a sector collapse on the west side of
the mountain above the headwaters of the Puyallup River. Such a lahar could partially overtop
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the ridge separating the Puyallup River and Tahoma Creek that empties into the Nisqually River.
This could cause delivery of services to be compromised in both watersheds.
All the problems that exist with an eruption triggered lahar are also inherent with a spontaneous
lahar. In addition delivery of services to citizens will be even more compromised in the case of a
spontaneous lahar because local agencies and jurisdictions will not have the lead up time to
evacuate equipment, records, and supplies from the valley bottom. Those that normally have
their equipment, supplies and records or backup copies, out of the impacted area will be able to
respond with at least some service delivery to those areas not directly impacted by the lahar.
Property, Facilities, and Infrastructure
Any Mt. Rainier major event, whether eruptive related or from a spontaneous lahar, will have a
major impact on the property, facilities and infrastructure of jurisdictions and agencies within the
confines of Pierce County as well as surrounding counties.
Tephra27
Tephra can collapse roofs, destroy engines, make roads slippery, clog both water and air
filtration systems, kill crops, clog drains, and short out electrical systems. All these can and will
affect jurisdictions and their ability to operate on a day to day basis. Depending on the depth and
distribution pattern of the ash, individual agencies or jurisdictions will be more or less impacted
by it. With more than one cm of ash having the ability to disrupt traffic by closing down roads
combined with the other damage listed above, it could take weeks for the local agencies and
jurisdictions to get their individual infrastructures back to normal.
Pyroclastic Flows
Pyroclastic flows by themselves, should only affect the infrastructure of the National Park. Any
effects outside the park will be the result of their impact on the snow and ice resident on the
volcano, melting it and initiating a lahar that could cause damage to facilities, property and local
infrastructure.
Lahars
Lahars are the primary force that will damage the infrastructure, property, and facilities. They
will flatten buildings, destroy equipment, bury roads, take out power lines, and destroy sewer
pumping systems. A major lahar coming down any of the river systems from Mount Rainier will
damage, destroy or bury all facilities, property and infrastructure that are above ground in the
impacted area. Only those areas on the periphery or where the flow weakens, thins out and
reduces in speed and volume will have any chance of survival.
Current buried pipes, power lines, etc. should not be damaged directly; although where they rise
to the surface they can be damaged. However, having a sewer line buried under an extra 15 feet
of mud in a community that no longer exists is essentially worthless. In areas where the lahar is
shallow, many of these underground utilities may be able to be rehabilitated.
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The extent of damage will be directly correlated with the quantity of debris the volcano coughs
up. Smaller lahars will not cover as much territory as the larger lahar would and will cause less
damage to those areas they do cover. This can be seen graphically on Map V-1. Here the Case 1
lahars are inclusive of all the territory also contained in Case 2 lahars and in addition all the area
highlighted in yellow.
Magmatic or Eruption Triggered Lahar
With a magmatic triggered lahar there will be time to evacuate records, supplies, and equipment
from the lahar’s path. How much of the material will actually be evacuated depends on the
length of time between when the volcano awakens and finally sends a lahar down valley. This
could be from a few hours to many days or weeks. The more time allowed the more that can be
saved.
Spontaneous Lahar
With a spontaneous lahar, there will be very little that jurisdictions can do to protect their
facilities, property or infrastructure located in its path. Those with resources further away from
the volcano will have a little time once the warning has been disseminated, but it may be too
little to make a major difference. Those agencies and jurisdictions will essentially have little or
no time to evacuate anything of value. That which was not protected prior to the initiation of the
lahar may be damaged or gone.
Environment
Environmental impacts will be dramatic and in some cases long lasting.
Tephra
Small tephra eruptions will have limited environmental impacts. Large tephra eruptions could
have dramatic impacts on the environment or ecology of large areas around Mt. Rainier. Because
under normal circumstances the prevailing wind patterns will blow much of the tephra to the east
impacting the upper White River and much of eastern Washington. In this scenario, plants and
animals in the White River valley could suffocate under the ashfall.
Tephra damage28 will partly depend on the size of the particles. Large pieces, one to two inches
or greater in diameter, can be very damaging. However, lethal impact from falling tephra is
likely only in the immediate vicinity of the volcano, generally within about six miles of the vent.
Animals not protected in this area could be severely injured or killed by the large particles.
Further away the finer grains begin to fall and can cause respiratory and eye irritation to animals,
burying plants and robbing the animals of their natural food supply. Ash washed down by the
rain will tend to add to the rest of the silt in the rivers and some of it will settle out downstream
possibly affecting the fish resources, including salmon that return up the various rivers.
A large tephra eruption that blows in other than an easterly direction could cause extensive, longterm environmental damage to much of the County. Having the same types of damage mentioned
above but spread over much of the County could cause environmental impacts that may take
years to recover from.
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Pyroclastic Flows
Pyroclastic flows by their very nature destroy everything in their path. They will burn the forest,
kill the wildlife and plants and boil the water in the rivers and lakes they enter. This destruction
will mostly be localized within Mt. Rainier National Park although the hot water in the streams
and rivers could cause fish kills for miles downstream. They could cause damage outside the
national park by starting wildfires in the park that could spread outside the park, or initiating
enough rapid melting from glaciers that lahars are created spreading damage for miles outside
the park.
Lahars
Lahars are the primary damaging factor associated with Mt. Rainier. Lahars descending the
valley will destroy and bury any and all plants and animals in their path. They can destroy
forested areas and they will silt up rivers and change their channels. They will add pollutants or
hazardous chemicals to the environment by the damage they do to manmade structures, vehicles,
sewage treatment facilities, etc. The addition of mud to the valley bottom by winter rains
bringing down more debris from upstream will continue to cause problems for the environment
possibly for a few years after the initial mudflow. They may totally destroy salmon habitat, and
the valley ecology in the areas they cover.
Those that reach Puget Sound could cover the near shore environment with silt and possibility
partially fill in Commencement Bay, and/or cover the shallow Nisqually delta and mud flats
creating a new surface and killing the creatures that currently make it home.
A new environmental balance will eventually be formed as plants and animals re-inhabit the area
covered by the mud. While it may take years for nature to repair the damage, it will eventually
reclaim those areas damaged by the lahar.
Economic and Financial Condition
Economic and financial affects will be of two parts. First is the damage to property, buildings,
inventories and equipment. Second is the loss of revenue due to the inability to get supplies
through the damaged area, the loss of markets, the decrease in population and, in some cases, the
loss of infrastructure to support the area economically.
Tephra
The damage to individual businesses, homes, and equipment could cause major financial losses
for individuals and businesses throughout Pierce County, but only if the wind does not blow the
ash to the east. If the wind does blow to the east as expected, then areas in the White River
Valley will be the ones affected. In this case, the Crystal Mountain ski area, and the homes
between it and the Greenwater area could be heavily damaged. The Greenwater businesses and
the Fire Department could all have structural building damage and the damage to vehicle engines
may prevent owners from evacuating to a safer area.
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Pyroclastic Flows
There should be little or no economic or financial effects directly from any pyroclastic flows
except to the National Park and those businesses located directly adjacent to the park boundaries.
However, the secondary damage from either the lahars or the forest fires started by the
pyroclastic flows could cause major economic problems depending on their size and the
community’s level of preparedness for them.
Forest fires started from the volcano will initially affect Federal land in the National Park and on
USFS land. Secondly, the fires could spread to Washington State DNR lands and could affect the
communities in the Nisqually Valley above Alder Lake; the Greenwater area in the White River
Valley; the towns of Carbonado and Wilkeson in the Carbon River drainage; and to homes in the
upper Puyallup. It must be remembered that all these communities, except for some in the upper
Nisqually, are further away from the volcano than the geologic record shows pyroclastic flows to
travel.
Lahars
Lahars have the potential to be the major destroyer of economic viability within Pierce County.
Any major lahar coming down one of the valleys from Mt. Rainier will destroy the homes,
businesses and much of the infrastructure within whichever valley it descends. Closer to the
mountain, like in Ashford or Elbe, some of it will be related to the tourist trade, or other
wilderness operations. Citizens there maintain their restaurants and shops along the mountain
highway, work in the National Park, or in many cases work for logging corporations, any or all
of which may be out of business because of a lahar.
In other cases like the cities of Puyallup, Sumner and Orting, there are thriving communities that
have been located on the valley floor for over 100 years, that have flourishing downtowns and
whose citizens are involved in the full range of occupations that any city or bedroom community
has in Washington. Many of them work in King County or the City of Tacoma. Many of them
have their own businesses in town. There are schools, medical clinics, libraries, fire stations, and
the Puyallup Fair Grounds. Any lahar that inundates these areas will be destroying vibrant
communities that have taken over a century to grow to their current size.
Those portions of these communities on the valley floor, which includes most of Puyallup,
almost all of Sumner and all of Orting could be destroyed totally with no viable way to regain
their economic base. It is not a question of rebuilding a few destroyed buildings as it would be
after an earthquake. With a lahar there may be no houses, no businesses and no infrastructure to
begin the rebuilding process. The result will be that there will be no population base for an
economic revival. People will have left the area. There will be no tax base for the cities to begin
their rebuilding process. With many feet of mud in the valley, and the threat of further flooding
and lahars, it will be awhile until people begin the rebuilding process.
Magmatic or Eruption Triggered Lahar
As the developing threat from the volcano is recognized by the scientists and they begin to warn
the public there will be some time for some people and business to move some of their
belongings, records and goods to higher ground. However no matter how much they are able to
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save this way, the economic recovery will be long and hard. With the destruction of homes and
the physical structures of the businesses in the valley, people will have no option except to leave
the area and find homes and work elsewhere.
Spontaneous Lahar
With a spontaneous lahar almost no community in the way of the lahar will have the ability to
adequately protect its assets. This is the worst case scenario. There could be a total loss of homes
and businesses in the impacted area. With buildings, equipment, records, inventories, and
community infrastructure gone, no business in the lahar zone will be able to restart immediately.
Even attempting to reestablish their business at a different location, outside the inundation zone,
will, in many cases, fall short. With the exodus by many members of the community, numerous
businesses will have little incentive to even attempt rebuilding in the valley.
Public Confidence in the Jurisdiction’s Governance
The reputation of an agency or jurisdiction as well as the public’s confidence in it will depend to
a great extent on the amount of planning and preparation that was done in anticipation of the
eventual event. This, combined with the open distribution of information to the public regarding
what is happening, could happen, and will happen during a volcanic event will greatly boost the
public’s confidence in the agencies and jurisdictions effected by it.
False alarms, alarmist pontificating, or confusion on what needs to be done will only lower the
public’s perception of the entity. Premature warnings of impending danger, especially if leading
to what is seen as unnecessary evacuation, will only weaken any entity’s authority.
Mt. Rainier is a big enough problem that good faith efforts put forth by the agencies and
jurisdictions will reap a good response from the public. Incompetence, will however, show
through and will destroy any reputation that the entity had before.
Tephra
Good information regarding what needs to be done to prevent or limit damage to property and
individuals will allow homeowners, businesses, and other local organizations to prepare for and
limit the damage from tephra. Any additional programs to assist them in alleviating the problem,
such as a community program to clean the ash off roofs, will help.
Pyroclastic Flows
Since there will be little or no direct damage from pyroclastic flows to agencies or jurisdictions
within Pierce County there should be little or no resulting loss of confidence from any
pyroclastic flow that descends Mt. Rainier.
Lahars
If an agency or jurisdiction produces good information ahead of time regarding what needs to be
done to prepare for a lahar, how to evacuate, upon receiving a credible lahar warning, limits false
alarms, and then puts out credible warnings, the confidence of the public will be largely
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maintained. If, on the other hand, false alarms become the norm, sirens do not work, and there is
confusion as to what people are supposed to do, the entity’s reputation will suffer. Any
confidence the public has in that entity will be lost.
Another factor affecting the eventual reputation is the ability to get infrastructure back up and
running as soon as possible. The fact that some areas will be unavailable, perhaps for years, will
take awhile for the public to accept. Even the visual clue of square miles of mud will not prevent
some people from complaining that local, state and federal agencies are not doing enough to help
them return to their pre-lahar state.
Magmatic or Eruption Triggered Lahar
A lahar triggered by an eruption will allow the local agencies more time to prepare for the
eventual destruction associated with it. They will have time to move resources, set up assistance
centers, evacuate people if necessary, and be seen as leading the response, not just being reactive
to the circumstances. In this case, those agencies and jurisdictions seen as preparing for the
potential lahar will maintain credibility with the public. Where this could break down is if an
evacuation is ordered based on the best geological evidence the scientists can provide and the
mountain does not produce a lahar. In this case, there could be citizen unrest as they want to get
back to their homes with the resulting loss of support for the actions of the local entity.
Spontaneous Lahar
In the case of a spontaneous lahar, the timely warning of an approaching lahar in the Puyallup
Valley should help in the maintenance of the local entity’s reputation. Even with some loss of
life, if the warning system operates as it is designed and all jurisdictions follow the Mt. Rainier
Volcanic Hazards Response Plan, confidence in the jurisdictions will remain intact.
This will not be the case if, without a warning a spontaneous lahar descends either the Nisqually
or the White River Valleys and impacts homes and businesses. In this situation, there would be
many questions about why no warning system was regarded as necessary on the Nisqually or
White River sides of the mountain and the reputation of government would be adversely
affected. The short time frame from when a spontaneous lahar is initiated to when it begins to
impact citizens in the Nisqually or White River Valleys does not allow enough time to put out an
EAS or telephone ringdown message to citizens in those valleys close to the mountain. Those
further downstream may be able to be reached in time to allow evacuation.
Vulnerability to Planning Area
The degree of hazard vulnerability is dependent on numerous variables. Those variables include
but are not limited to as stated before: the type and size of the event; time of day; amount of
warning time; size of population in harm’s way; special needs populations (physically or
mentally impaired); weather conditions; transportation availability; emergency response
capabilities, and; type of warning methods.
The potential hazards posed by Mount Rainier have led to its inclusion as one of sixteen
volcanoes worldwide to be designated Decade Volcanoes. The Decade Volcano initiative is part
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of a United Nations program aimed at better utilizing science and emergency management to
reduce the severity of natural disasters. The Decade Volcanoes are the focus of coordinated
earth-science studies and land-use planning to learn the best ways to reduce the risks to life and
property from volcano-related hazards.
The Planning Team determined that the Planning Area has a medium vulnerability to the
volcanic hazard. Although the probability of recurrence is low, a lahar is a high consequence
event that would kill people and destroy buildings, infrastructure and cultural and sacred sites as
well as natural resources. Mt. Rainier’s location within the County and its proximity to
population centers help elevate this vulnerability. The Planning Area is known to have
experienced debris flow, heavy ashfall, or blast effects from past volcanic activity, and the
effects of these are described above.
Many of the Tribe’s structures and served population are located in lahar inundation path. In the
event of a lahar, the Tribe’s response would include evacuation and accommodation of
potentially thousands of permanently displaced people. A lahar would also destroy resources
and have high direct and indirect economic impact. A lahar would cause numerous fatalities,
destroy many properties, destroy resources and have high direct and indirect economic impact.
According to Map 4.5-1, the estimate lahar travel time for the Reservation’s southern boundary
is just over 80 minutes following the automated warning.
In the entire Planning Area, over 18,000 acres are vulnerable to the volcanic tephra hazard. The
total damage to the planning Area could equal approximately $8 billion (the assessed value of all
parcels in the Planning Area.)
A more detailed vulnerability assessment by the Planning Team showed that approximately
8,826 acres (56.6% of the Planning Area) are located in volcanic lahar inundation zones making
those acres even more vulnerable to the volcanic hazard. The total estimated losses to these
parcels would be $4.2 billion.
For Tribal Trust parcels located in the Planning Area, all 485 parcels are vulnerable to the
volcanic tephra hazard. The total estimated losses to these parcels would equal $3 million.
Of the 485 Tribal Trust parcels in the Planning Area, 185 parcels (38.1%) are located in volcanic
lahar inundation zones. The total estimated losses to these parcels would equal $252 million.
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Figure 4.5-6 Mt. Rainier
Lahar flows
Lahar flows can overwhelm roads and railroad tracks, destroy bridges and other public and
private property, kill both wildlife and the people caught in the path, and destroy forest and other
agricultural products grown. In addition, a lahar flow can destroy the rivers’ fish, which may take
years to restock, if ever. With the potential of lahars containing cohesive clays, damage can
occur up to100 km downstream (with Mt. Rainier, this would be all the way to Puget Sound). As
per the Land Settlement Agreement, the Tribe owns the bed of the Puyallup River within the
Reservation boundary. Further the Tribes extensive commitment to salmon habitat and
populations leads to the Tribes unique vulnerability to this hazard.
Lahars that do not have the mass or force to reach anywhere near the Reservation can still have a
large negative impact on both the Puyallup River and the resources associated with it. Currently,
there is more than 20 times as much ice locked up in the glaciers of Mt. Rainier than that which
existed on Mount St. Helens prior to the 1980 eruption. In the 1980 eruption, this ice melted
almost instantaneously.29 A water volume of that magnitude melting instantaneously and
funneling down the Puyallup Valley would have a catastrophic effect on the Tribe’s fisheries and
commerce.
A large-scale eruption of Mt. Rainier has the potential to alter the region’s topography,
population centers, and economic foundation for years and possibly decades. A Case I lahar
could destroy much of the reservation as well as natural resource areas further upriver and much,
if not all, of the port-industrial area of Commencement Bay. Portions of the deepwater Port,
would remain clogged with material for some time.
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The amount of debris that could fill the valley in the neighborhood of Sumner could be enough
to block the White River, backing up water into the City of Auburn. The lahar deposits could
remain soft and muddy for weeks, either drastically inhibiting transportation and cleanup or
making it impossible. Loss of transportation would have a negative impact upon the Tribe’s
business interests. Therefore mitigating the loss of transportation routes is necessary for the
Tribe’s long-term economic sustainability.
In addition there is the possibility of continued smaller mudflows. Some of these will occur as
rain continues to wash mud from the upper valley, where some of it settled out during the initial
flow, into the lower Puyallup Valley. Some will come from the damming of side streams and
rivers, which would then form new channels, and in some cases lakes that would, as they filled
up, eventually either break through or overtop the mud damming them, thus creating new floods
in the valley. All of these would exacerbate the problem of cleanup and recovery. The actual
recovery time for some areas might be counted in years rather than weeks or months.
Tephra
Under normal wind conditions, the deposition of tephra should travel to the northeast, affecting
the upper White River basin and much of eastern Washington rather than the populated areas of
Pierce County. For the full effects of a tephra eruption to be felt in Pierce County, Mt. Rainier
would have to erupt at the same time of a southeast wind. This would deposit the majority of ash
in western Washington, especially in the populated areas of Pierce County.30
Depending on the size of the eruption, weather, and time of year, the ash could do any number of
the following to the Planning Area: clog drainage channels; cause electrical short circuits; drift
onto roadways and rail lines causing accidents; collapse roofs of houses and other buildings;
cause skin and eye irritation to the general population and/or respiratory distress to the aged, the
infirm, the very young, or those who with already decreased respiratory flow; clog engines and
air filters, and; create acid rain, which may effect water supplies, strip paint, burn foliage,
corrode machinery, and age fabric.31
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Resource Directory
Regional
o Pierce County Department of Emergency Management
http://www.co.pierce.wa.us/PC/Abtus/ourorg/dem/abtusdem.htm
o Mt. Rainier National Park
http://www.nps.gov/mora/
http://www.mount.rainier.national-park.com/
o Mt. Rainier Seismicity Information
http://www.geophys.washington.edu/SEIS/PNSN/RAINIER/rainier.html
o Pacific Northwest Seismograph Network
http://www.geophys.washington.edu/SEIS/PNSN/INFO_GENERAL/volcanoes.html
o USGS Cascade Volcano Observatory
http://vulcan.wr.usgs.gov
o USGS Lahar Warning System: Mt. Rainier
http://volcanoes.usgs.gov/About/Highlights/RainierPilot/Pilot_highlight.html
o Washington State Department of Natural Resources
http://www.wa.gov/redirDNR/splash.html
National
o Alaska Volcano Observatory
http://www.avo.alaska.edu/avo4/products/hazard.htm
o Smithsonian Institution Global Volcanism Program
http://www.nmnh.si.edu/gvp
o USGS Volcano Themes
http://www.usgs.gov/themes/volcano.html
o Volcano Hazard Maps
http://volcanoes.usgs.gov
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Endnotes
1
Background and specific information for entire Pierce County Volcano Section provided through consultation with
volcanic hazard expert, Tim Walsh, Washington State Department of Natural Resources.
2
Modified from PC HIVA (DRAFT), Volcano Section, September 5, 2002, p. 1.
http://www.co.pierce.wa.us/pc/abtus/ourorg/dem/EMDiv/HIVA/VOLCANIC.pdf
3
US Geological Survey Cascade Volcano Observatory
4
Debris flow at Tahoma Creek, July 26, 1988.,USGS Photo Archives, Photo by G.G. Parker, July 26, 1988,
http://vulcan.wr.usgs.gov/Volcanoes/Rainier/images.html
5
Walder and Driedger, 1993, Volcano Fact Sheet: Glacier-generated debris flows at Mount Rainier: USGS OpenFile Report 93-124
6
Ibid, Pringle and Scott.
7
Pringle, Patrick and Scott Kevin, Postglacial Influence of Volcanism on the Landscape and Environmental History
of the Puget Lowland, Washington: A Review of Geologic Literature and Recent Discoveries, with Emphasis on the
Landscape Disturbances Associated with Lahar, Lahar Runouts, and associated Flooding, p.10
8
Scott, K.M., Vallance, J.W., Pringle, P.T., Sedimentology, Behavior, and Hazards of Debris Flows at Mount
Rainier, Washington, U.S. Geological Survey, U.S. Geological Survey Professional Paper 1547, U.S. GPO, 1995
PP7-8x.
9
Hobblett, R.P. et al, Report: volcano Hazards from Mount Rainier, Washington, Revised 1998, U.S. Geological
Survey Open-File Report 98-428 accessed at http://vulcan.wr.usgs.gov/Volcanoes/Rainier/Hazards/OFR98428/OFR98-428.html
10
Rockfall Avalanche, Mt. Rainer, Washington, Results of the 1963 rockfall avalanche of volcanic debris on Little
Tahoma, Mt. Rainer, Washington. There were no witnesses to the event., Geologic Hazards Photos Volume 3
Landslides, Tsunamis, and Volcanoes, http://www.ngdc.noaa.gov/seg/cdroms/geohazards_v3/document/647006.htm
11
www.nsm.buffalo.edu/courses/gly433/Pyroclast.pdf
12
Walder and Driedger, p. 2.
13
Hazard zones for lahars, lava flows and pyroclastic flows from Mount Rainier (Hoblitt and others, 1998: US
Geological Survey Open file Report 98-428, accessed at
http://vulcan.wr.usgs.gov/Volcanoes/Rainier/Publications/FS065-97/FS065-97_map.pdf
14
K.M. Scott, P.T. Pringle, and J.W. Vallance, Sedimentology, Behavior, and hazards of Debris Flows at Mount
Rainier, Washington, U.S. Geological Survey, Open File Report 90-385, P.80-84
15
T.C. Pierson, Estimated Lahar Travel Times for Lahars 107 to 108 Cubic Meters in Volume
(Approaching a ‘Case 1’ Lahar in Magnitude) in the Puyallup River Valley, Mount Rainier, and Estimated Lahar
Travel Times for Lahars 107 to 108 Cubic Meters in Volume (Approaching a ‘Case 1’ Lahar in Magnitude) in the
Carbon River Valley, Mount Rainier, Revised October 11, 2001, U.S. Department of the Interior, U.S. Geological
Survey.
16
Swanson, D.A. et al. Excerpt from Cenozoic volcanism in the Cascade Range and the Columbia Plateau, Southern
Washington and Northern Oregon: AGU field Trip Guidebook T106, July 3-8 1989 as quoted in an excerpt at
http://vulcan.wr.usgs.gov/Volcanoes/PacificNW/AGU-T106/rainier.html
17
USGS, http://vulcan.wr.usgs.gov/Volcanoes/Rainier/Outreach/rainier_posters.html
18
W.E. Scott, R.M. Iverson, J.W. Vallance, and W. Hildreth, Volcano Hazards in the Mount Adams Region,
Washington: U.S. Geological Survey Open-File Report 95-492 1995, accessed at:
http://vulcan.wr.usgs.gov/Volcanoes/Cascades/Hazards/ash_accumulation_10cm.html
19
http://vulcan.wr.usgs.gov/Volcanoes/Cascades/EruptiveHistory/cascades_eruptions_4000yrs.pdf
20
Mt. Rainier, Active Cascade Volcano, National Research Council, National Academy Press, Washington DC,
1994, pps.42-43.
21
USGS, http://vulcan.wr.usgs.gov/Volcanoes/PacificNW/AGU-T106/rainier.html
22
Lyn Topinka, Mount St. Helens: A General Slide Set GS9,
http://vulcan.wr.usgs.gov/Volcanoes/MSH/SlideSet/ljt_slideset.html
23
Description: Mount Rainier Volcano, USGS Cascade Volcano Observatory,
http://vulcan.wr.usgs.gov/Volcanoes/Rainier/description_rainier.html
24
Email correspondence from William E. Scott, USGS geologist, David A. Johnston, Cascade Volcano
Observatory, 2/26/08.
25
Volcanic Ash: How to be Prepared for an ashfall, USGS, and Washington Military Department, Emergency
Management Division pamphlet, June 2003
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26
Deadly Lahars from Nevado del Ruiz, USGS Volcano Hazards Program, Colombia, November 13, 1985,
http://volcanoes.usgs.gov/Hazards/What/Lahars/RuizLahars.html
27
Materials in this section on tephra are from the Cascades Volcano Observatory website
http://vulcan.wr.usgs.gov/Hazards/NRC_Definitions/tephra.html
28
Much of this section is taken from Volcanic-Hazard Zonation for Mount St. Helens, Washington 1995, by Edward
Wolfe and Thomas Pierson, USGS Open-File Report 95-497.
29
Ibid, p. 5, 6.
Ibid, p. 5, 6.
31
Ibid, p. 5, 6.
30
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This is a copy of a public record, reproduced as it was published. It is not legal advice, and it may not be the version a court would rely on. Check the official source before you cite it.