Geologic Risk for Washington State

Washington geological survey

LANDSLIDES, VOLCANOES, EARTHQUAKES, AND TSUNAMIS POSE SERIOUS THREATS TO WASHINGTON’S ECONOMY. WHETHER THEY HAPPEN NEXT YEAR OR IN 50 YEARS, LOSSES ARE LIKELY TO BE DEVASTATING, AND UNDERSTANDING OUR RISKS HELPS INCREASE OUR RESILIENCY

www.dnr.wa.gov/geology 2 What is Geologic Risk?

GEOLOGIC RISK CAN BE DEFINED AS THE COMBINATION OF HAZARD, VALUE, AND VULNERABILITY 1

EVENT WITH N GIC EGA LO TIV EO AND SOME C E G CTS HA PA NC M OCCURREN E I OF CE

Y T T A O I N L T I A D B L I P T R V P A E S O L P U C D E E S R R U A T O S Z VO Y F G A E LC T N H ID AN IN HE YI L O H P VAR TO S A EOPLE D

ZA N I RD A

ZONE L M E A A N RISK ANALYSIS ANSWERS THREE BASIC QUESTIONS: RTH SU QUAKE T 1. What geologic hazards exist in the community?

2. What is the likelihood of hazard events occurring?

3. What are the consequences if the hazard event occurs?

www.dnr.wa.gov/geology What is Geologic Risk? 3

GEOLOGISTS LOOK AT THE large GEOLOGIC RECORD TO DETERMINE HOW OFTEN EACH THE CONSEQUENCES OF HAZARD IS LIKELY TO OCCUR. GEOLOGIC DISASTERS SMALL GEOLOGIC ARE INVERSELY EVENTS HAPPEN FREQUENTLY. PROPORTIONAL TO HOWEVER, EVERY FEW HUNDRED THEIR FREQUENCY YEARS, WE CAN EXPECT ONE OR MORE DISASTROUS EVENTS. THESE LARGE EVENTS HAVE LEFT INDELIBLE MARKS ON THE

LANDSCAPE AND OUR LIVES. size of consequences

small infrequent frequency of frequent hazard event

IN WASHINGTON STATE, THE MOST SIGNIFICANT GEOLOGICAL VOLC IDE AN HAZARDS ARE EARTHQUAKES, SL O D TSUNAMIS, VOLCANIC

N I

A ERUPTIONS, AND LANDSLIDES. L

M A EA OTHER GEOLOGIC HAZARDS R UN THQ TS INCLUDE SUBSIDENCE ABOVE UAKE IMPROPERLY ABANDONED MINES, RADON, AND OTHER HAZARDOUS MINERAL EXPOSURE.

www.dnr.wa.gov/geology 4 Hazard, Value, and Vulnerability

THE ECONOMIC CONSEQUENCES OF A POTENTIAL GEOLOGIC HAZARD ARE DETERMINED BY CALCULATING THE VALUE OF PROPERTY AND INFRASTRUCTURE IN AREAS LIKELY TO BE AFFECTED BY THAT HAZARD

BENEFIT-COST ANALYSIS Once the value of loss is known, a benefit-cost analysis may be performed to determine if any mitigation step taken to reduce vulnerability to hazards is an effective use of tax dollars.

HOW IS TOTAL FINANCIAL LOSS CALCULATED? The total financial worth of a given area is defined as direct loss of people, property, and infrastructure. One could go a step further and add in the monetary value of losses that would occur from disruption of the local or regional economy after a major disaster. FEMA considers a statistical life to be on average worth $6.3 million. This is the amount FEMA uses in benefit-cost analyses.

www.dnr.wa.gov/geology Annualizing Loss 5

GEOLOGIC BENEFIT-COST ANALYSIS IN ACTION: The Ocosta Elementary School Vertical Tsunami Evacuation Structure In 2012, Grays Harbor county residents voted on a bond measure to add a vertical tsunami evacuation structure—worth ~$2 million—to the Ocosta Elementary school. The 10,000 square foot structure is designed to be a safe refuge for 1,000 coastal evacuees, where much of the land will likely be inundated during a tsunami from which escape on foot is extremely challenging. The benefit-cost analysis for building this structure was simple, as the low cost was easily outweighed by the lives that will be saved by its construction. Additional vertical evacuation structures in coastal communities in Pacific County are now in the the planning stages.

>1,000 LIVES SPARED

VERTICAL TSUNAMI EVACUATION STRUCTURE COST ~$2 million

www.dnr.wa.gov/geology 6 Earthquakes

WASHINGTON STATE IS RANKED SECOND IN TERMS OF SEISMIC RISK IN THE NATION

Washington has a high earthquake An earthquake scenario hazard and has experienced ~15 for the Seattle Fault C shows estimated losses A earthquakes that have caused S building damage since 1872. for a M6.7 event would be C 2 Additionally, geologic evidence about $33 billion. A demonstrates substantial hazard D Additionally, there is substantial I from faults that have not ruptured A evidence that the Cascadia SEATTLE since European settlement of the subduction zone is active and Pacific Northwest. Many of these has generated earthquakes TACOMA faults are capable of earthquakes 3 larger than magnitude (M)6.5 at greater than M9.0. a df adfasdfa S shallow—and therefore highly dfa df adf f adf fad dfadf dfadfasdf U damaging—depths. dTHE d ddd1994 dddhdh M6.7 NORTHRIDGE, dh hdh hdhh CAh dh B hhhhhEARTHQUAKE h h hd hhh KILLED hhh h60 PEOPLE D YAKIMA AND COST UP TO $40 BILLION U WALLA (IN 1994 DOLLARS) C

T WALLA

www.dnr.wa.gov/geology Earthquakes 7

61,420 WASHINGTONIANS LIVE IN AREAS HIGHLY VULNERABLE TO LIQUEFACTION DURING AN EARTHQUAKE

Faults are breaks in the Earth’s crust that

C form from tectonic stresses. Rupture occurs A along faults during earthquakes. Most of S Washington’s faults have not ruptured since C European settlement of the Pacific Northwest. A D damaging active I A SEATTLE earthquake fault since 1872

TACOMA

D YAKIMA

U WALLA C

T WALLA

FOR WASHINGTON STATE, THE IMPACT OF A M9.0

O CASCADIA SUBDUCTION ZONE EARTHQUAKE HAS N BEEN ESTIMATED AT 4 E $49 BILLION

EARTHQUAKES ON THE CASCADIA SUBDUCTION ZONE RECUR ON AN AVERAGE OF EVERY 500 YEARS YEARS OR SO. THE LAST OCCURRED IN AD 1700, BUT MAJOR QUAKES CAN RECUR EVERY 200 TO 1,000 YEARS. www.dnr.wa.gov/geology 8 Tsunamis

Washington has a moderate TSUNAMI RISK CHANGES hazard of distantly generated SON WITH THE SEASONS tsunamis. The tsunami associated EA N S TIO Y A as coastal populations with the 1964 M9.2 Alaska N L I U A P earthquake was the largest O increase dramatically R historic event in Washington. P 50K in summer months Damage estimates were more than N

O $775,000 to homes and bridges S >200K A N E and more than $1.5 million (both O S I T T S A in 2016 dollars) to oyster beds in RI L TOU PU sparsely populated Willapa Bay. PO BELLINGHAM Tsunamis generated locally pose a much greater hazard, both because they arrive quickly SAN S and because they can be much TR JUAN AIT OF larger than distantly generated JU ISLANDS AN tsunamis—as high as 50 feet in DE FUCA some areas.

Geologic evidence demonstrates Red areas indicate that a tsunami was generated by an earthquake on the Seattle fault tsunami inundation about 1,000 years ago. modeling coverage O

U to date The largest tsunami in Washington T SEATTLE E

in the last 500 years was R ON AVERAGE, CASCADIA SUBDUCTION generated on the Cascadia C O

subduction zone on January 26, A ZONE EARTHQUAKES GENERATE

1700. Sand sheets deposited by T TACOMA TSUNAMIS EVERY 500 YEARS it are found from British Columbia to northern California, and it was recorded in both Native American GRAYS and Japanese records. 3 HARBOR 47,863 WASHINGTONIANS 2011 TOHOKU TSUNAMI ~$300 billion in total damages LIVE IN THESE 15,894 fatalities HAZARD ZONES www.dnr.wa.gov/geology Tsunamis 9

A TSUNAMI IN THE SEATTLE AREA FROM A SEATTLE FAULT EARTHQUAKE HAS A RECURRENCE INTERVAL OF ~2,500 YEARS 2 The assessed value in the tsunami first year. Loss is compounded when inundation zone along the outer coast considering that ground subsidence and the Strait of Juan de Fuca is accompanying these events takes ~$4.5 billion, and businesses in the several decades to rebound, zone generate $4.6 billion in annual significantly delaying any rebuilding. sales volume. 11 Fragility curves (the damage vulnerability of buildings Loss of life in a tsunami depends for a geologic event) have yet to largely upon time of year, time of day, be developed for tsunamis, but the and citizen response. A reasonable state of Oregon has adopted 25% of estimate for fatalities during a total value for its damage estimates. Cascadia subduction zone tsunami That would suggest ~$1 billion in is 10,000. FEMA’s benefit-cost model property losses and a total loss of currently assumes the Value of a business revenue generated there. Statistical Life of $6.3 million, yielding Total economic losses in Washington an estimated loss of $63 billion from loss of life alone. would likely exceed $6 billion in the ON AVERAGE, CASCADIA SUBDUCTION ZONE EARTHQUAKES GENERATE TSUNAMIS EVERY 500 YEARS

www.dnr.wa.gov/geology 10 Landslides

1998 1894 Allyn Curves Puyallup River delta Landslides; submarine landslide $10–15 million in kills 2, destroys railroad damage to SR-3 track and roadway 1965 ~1500 April 29th earthquake Bonneville Landslide; near Tacoma triggered 1990 1998 blocked Columbia 21 landslides within 60 KM Mountain Aldercrest-Banyon River ~1700 miles of epicenter Landslide; Landslide; Cascadia subduction 138 homes lost 2009 $5 million in Most recent zone earthquake >$110 million in damage Lake Roosevelt triggered numerous 1994 damage 1872 Peters Road 2001 landslide and landslides Nisqually North Cascades Landslide; tsunami Earthquake; earthquake triggered $10–15 million in >$34.3 million in a landslide that damage to SR-112 dammed the landslide damage 2007 2009 Columbia River 1990 winter storm 1949 Clallam County winter storm >2,000 >1,500 landslides; Puget Sound Landslides; landslides; $61 million in earthquake triggers $10 million in $82 million FEMA assistance widespread landslides damage to SR-112 in FEMA assistance 2014 SR530 1980 Landslide; Mount St. Helens 43 deaths, Landslides are one of the most frequently occurring natural hazards, but they’re eruption >$80 million in notoriously difficult to quantify both in terms of frequency and cost. Inventories of unleashed by 1996–1997 damage winter storms landslides for the state are not comprehensive, and in most cases, landslides are largest debris avalanche in damage or destroy 2006 neither noticed nor reported. nearly 8,000 homes recorded history Rockcrusher Hill 2009 Extreme winter precipitation events in western Washington can produce more than 1987 Landlside; Nile Landslide; 1999 >$7 million repair $22 million in Prosser 1,500 landslides in a period of a few hours to weeks. And large, slow-moving slides Carlyon Beach to U.S. Hwy 101 direct costs destroy or damage homes and roads several times per month every winter. Landslides; Landslide; $10–15 million 33 homes lost in damage to Large and damaging events, such as the SR-530 (Oso) landslide or Aldercrest- 2013 Interstate 82 1992 2006 Satus Pass Ledgewood-Bonair Banyon in Kelso happen less frequently, but cost millions, and most of this damage is winter storms Landslide; Landslide; not covered by insurance. FEMA is relied upon in these large events to assist in loss $7.3 million in $5 million in 2 homes destroyed damage to recovery. Federal assistance frequently recovers only about 20 cents on the dollar. If damage to infrastructure no federal disaster declaration is made, assistance is more often zero. U.S. Hwy 97

www.dnr.wa.gov/geology Landslides 11

1998 THE 2001 NISQUALLY 1894 Allyn Curves EARTHQUAKE CAUSED Puyallup River delta Landslides; submarine landslide $10–15 million in LANDSLIDE DAMAGE kills 2, destroys railroad damage to SR-3 7 track and roadway OF >$34.3 MILLION 1965 (IN 2001 DOLLARS) ~1500 April 29th earthquake Bonneville Landslide; near Tacoma triggered 1990 1998 blocked Columbia 21 landslides within 60 KM Mountain Aldercrest-Banyon River ~1700 miles of epicenter Landslide; Landslide; Cascadia subduction 138 homes lost 2009 $5 million in Most recent zone earthquake >$110 million in damage Lake Roosevelt triggered numerous 1994 damage 1872 Peters Road 2001 landslide and landslides Nisqually North Cascades Landslide; tsunami Earthquake; earthquake triggered $10–15 million in >$34.3 million in a landslide that damage to SR-112 dammed the landslide damage 2007 2009 Columbia River 1990 winter storm 1949 Clallam County winter storm >2,000 >1,500 landslides; Puget Sound Landslides; landslides; $61 million in earthquake triggers $10 million in $82 million FEMA assistance widespread landslides damage to SR-112 in FEMA assistance 2014 SR530 1980 Landslide; Mount St. Helens 43 deaths, eruption >$80 million in unleashed by 1996–1997 damage largest debris winter storms avalanche in damage or destroy 2006 nearly 8,000 homes recorded history Rockcrusher Hill 2009 1987 Landlside; Nile Landslide; 1999 >$7 million repair $22 million in Prosser Carlyon Beach to U.S. Hwy 101 direct costs Landslides; Landslide; $10–15 million 33 homes lost in damage to 2013 Interstate 82 1992 2006 Satus Pass Ledgewood-Bonair winter storms Landslide; Landslide; $7.3 million in $5 million in 2 homes destroyed damage to damage to infrastructure U.S. Hwy 97

www.dnr.wa.gov/geology 12 Volcanoes

THE PRINCIPAL HAZARDS POSED ASH FALL BY VOLCANOES ARE Mount St. Helens (at least twelve eruptions in the last 4,000 years) ASH FALL AND and Glacier Peak (at least six LAHARS eruptions in the last 4,000 years) are the Washington volcanoes most likely to produce ash. 9 Ash eruptions pose a significant hazard to aircraft, and accumulations of ash can cause severe impact damage, respiratory problems, short-circuiting of electrical equipment, reduced visibility, fouling of machinery, and burial of structures, potentially LAHARS causing roof collapse. Ash in a lateral blast can have devastating Lahars, or volcanic debris flows, can impacts near the volcano. travel far from the volcano and inundate areas with mud tens of feet thick.

About 600 years ago, a large lahar buried N

the present site of the city of Orting 30 T AS E IM Y C AR PA B feet deep and likely continued to flow C TE D E R I down the Puyallup River to Puget Sound. D VOL CAN S H D If this were to happen today, damage to I C A IN W

structures would total an estimated $13 PO G U N N 8 D TH I N E L E I billion. P P A E R E V D

Y E L S Mount Rainier, Glacier Peak, and Mount L AR G DUR O N ING E UPTI Baker all pose this level of lahar hazard R to significant population centers. 500,583 LAHARS THAT TRAVEL A WASHINGTONIANS SIGNIFICANT DISTANCE FROM THE VOLCANO HAVE LIVE IN VOLCANO RECURRENCE INTERVALS ON THE ORDER OF 500 YEARS HAZARD ZONES www.dnr.wa.gov/geology Volcanoes 13

THE 1980 ERUPTION OF MOUNT ST. HELENS KILLED 57 PEOPLE AND COST AT MOUNT LEAST $2.9 BILLION BAKER 9 IN 2016 DOLLARS

GLACIER PEAK

RISK IS INCREASING Between 1990 and 2010, expansion into lahar hazard zones increased by 48,080 residents 10 At present, only two river valleys near Mount Rainier have lahar warning systems in place— areas with other valleys have lahar warning MOUNT none systems in RAINIER place

MOUNT volcano hazard ADAMS zones, excluding ash fall 500,583 MOUNT WASHINGTONIANS ST. HELENS LIVE IN VOLCANO HAZARD ZONES www.dnr.wa.gov/geology 14 Resiliency

Tsunami or lahar siren Vertical evacuation structure Tsunami inundation modeling coverage BELLINGHAM MOUNT SAN BAKER JUAN Volcanic hazard zone ISLANDS ST RA Lahar warning system IT O F J UAN in place DE FUCA GLACIER PEAK

EVERETT

WAYS TO R

C SEATTLE LAHAR O

A TACOMA WARNING REDUCE S

T SYSTEM RISK AND

VERTICAL MOUNT LESSEN EVACUATION RAINIER STRUCTURE IMPACTS

MOUNT ●● Evaluate geologic hazards at ADAMS statewide level ●● Make schools structurally resilient MOUNT ●● Require utility providers to identify ST. HELENS and mitigate for vulnerabilities in systems before, during, and after an emergency ●● Identify and replace aging or vulnerable infrastructure in areas of high seismic hazard ●● Build additional vertical tsunami evacuation structures in vulnerable coastal communities to reduce loss of life ●● Reinforce or replace unreinforced masonry buildings to better withstand shaking ●● Enforce and update building codes ●● Encourage and facilitate emergency planning at a community level ●● Ensure continuity of health care after emergencies www.dnr.wa.gov/geology References 15

RISK CAN BE REDUCED BY: ●● mitigate the hazard through improvement of soil engineering properties

●● limiting the value residing in

hazard zones with improved

hazard mapping, land-use

planning, preparedness, and evacuation techniques ●● limiting vulnerability to hazards, through improved building codes or relatively inexpensive seismic retrofits

REFERENCES CITED

1. Dibble, R. R.; Nairn, I. A; Neall, V. E., 1985, Volcanic hazards of North Island, New Zealand—Overview: Journal of Geodynamics, v. 3, pp. 369-396. 2. Earthquake Engineering Research Institute and Washington Military Department Emergency Management Division, 2005, Scenario for a Magnitude 6.7 earthquake on the Seattle Fault: Earthquake Engineering Research Institute and Washington Military Department Emergency Management Division, 162 p. 3. Atwater, B. F.; Satoko, M.; Satake, K.; Yoshinobu, T.; Kazue, U.; Yamaguchi, D. K., 2005, The orphan tsunami of 1700— Japanese clues to a parent earthquake in North America: U.S. Geological Survey Professional Paper 1707, 133 p. 4. Washington State Emergency Management Council—Seismic Safety Committee, 2012, Resilient Washington State—A framework for minimizing loss and improving statewide recovery after an earthquake: Washington Division of Geology and Earth Resources Information Circular 114, 33 p. 5. Atwater, B. F.; Moore, Andrew L., 1992, A tsunami about 1000 years ago in Puget Sound, Washington: Science, v. 258, no. 5088, p. 1614-1617. 6. Wood, N.; Soulard, C., 2008, Variations in community exposure and sensitivity to tsunami hazards on the open-ocean and Strait of Juan de Fuca coasts of Washington: U.S. Geological Survey Scientific Investigations Report 2008-5004, 34 p. 7. Highland, L. M., 2003, An account of preliminary landslide damage and losses resulting from the February 28, 2001, Nisqually, Washington, Earthquake: U.S. Geological Survey Open-File Report 03-211. 8. Cakir, Recep; Walsh, T. J., 2012, Loss estimation pilot project for lahar hazards from Mount Rainier, Washington: Washington Division of Geology and Earth Resources Information Circular 113, 17 p. 9. Washington Emergency Management Division, 2008, Washington State enhanced hazard mitigation plan: Washington Military Department. 10. Diefenbach, A. K.; Wood, N. J.; Ewert, J. W., 2015, Variations in community exposure to lahar hazards from multiple volcanoes in Washington State (USA): Journal of Applied Volcanology, v. 4, no. 4, 14 p.

www.dnr.wa.gov/geology 16 Washington Geological Survey

WE WORK TO REDUCE RISK AND FUTURE LOSSES FROM GEOLOGIC HAZARDS BY RAISING PUBLIC AWARENESS AND INFORMING TRAINED EXPERTS.

HAZARD ACTIVE FAULT MAPPING STUDIES TSUNAMI LOCAL INUNDATION JURISDICTION MODELING ASSISTANCE

SCIENCE EDUCATION AND ADVISORS OUTREACH

EMERGENCY SOCIO-ECONOMIC RESPONSE LOSS MODELING

WITHOUT GEOLOGICAL HAZARD ASSESSMENTS, RISKS WOULD BE UNKNOWN, AND BUILDING STANDARDS WOULD BE BASED ON MERE GUESSWORK.

A RESILIENT SOCIETY PLANS FOR UNSCHEDULED EVENTS.

http://www.dnr.wa.gov/geology