GEOLOGIC HAZARDS IN WASHINGTON STATE 1 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 hazard risk y t i l Y T i T A O I N L T b I A D B L v a I P T R V a r P A E S O L l e P U u n C D E E e l S R R vu U A T O S Z VO Y F G A E LC T N H D AN IN H YI LI O E R O S H PE VA T D A OPLE 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 I O N Z O N E 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 S U B D YAKIMA U WALLA C T WALLA I O N FOR WASHINGTON STATE, THE IMPACT OF A M9.0 Z 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 S 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.