cascadia deep earthquakes

8/11/2019 Cascadia Deep Earthquakes

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Also published as Open File Report 2008-1 by the Washington Division of Geology and Earth Resources

2008


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2 CREW Deep Earthquakes in Cascadia, 2008

Deep earthquakes

D

eep earthquakes pose a serious risk to Cas-cadia. In Puget Sound, for example, thereis an 84% chance of a magnitude 6.5 orgreater deep earthquake striking within 50

years. Beneath northwestern California, northwesternOregon and southwestern British Columbia the prob-ability of a similar sized earthquake over 50 years issomewhat lower, but still a major component of theearthquake hazard in each area.

The most recent deep event was a M6.8 earthquake onFebruary 28, 2001, centered under the Nisqually delta.Building walls crumbled, bridge supports cracked, andthe cost ultimately tallied at $4 billion. The number ofinjuries exceeded 400, but resulted in only one death.

The Nisqually earthquake was deep, because the faultslipped almost 30 miles (50 kilometers) underground.

Deep earthquakes are particularly important becauseof their frequency. Preparing for a deep earthquakewill help prepare you for other types of earthquakesthat put the region at risk.

Deep earthquakes characteristics in Cascadia

They occur generally below depths of 18 miles (30kilometers) on fractures within the subducting sea-floor plate. Northern California deep earthquakesmay be shallower.

They are usually less than M7.5.

Damaging deep earthquakes occur every 10-30years in the Puget Sound area.

Because the faults break so deeply, the seismicwave energy they radiate spreads over a muchlarger area than in a shallow quake. A larger areaexperiences significant shaking, although muchless so directly above the fault, than in a similar-sized shallow quake.

Few, if any, aftershocks occur.

No tsunami is expected, although landslides couldtrigger local tsunamis.

Potential hazards

Primary hazards include ground shaking (which can

be increased locally by poor soils) and ground failure(including liquefaction and landslides). These can alsoproduce secondary hazards, such as ruptured utilitylines, hazardous spills, and fires. Damage to buildingsand bridges is probably the most visible and danger-ous. Unreinforced masonry (URM) and other types of

buildings can fail, burying streets with rubble or trap-ping people inside. Other types of buildings are also atrisk. Failed bridges can disrupt entire neighborhoods

for months after an earthquake.

Recent earthquakes

Recent deep earthquakes in the Puget Sound area

show similar general patterns of damage, thoughthe details of each was different, depending on thesize of the event, the epicenter, and the affected builtenvironment.

Deep earthquakes have also occurred under PenderIsland, British Columbia; Corvallis, Oregon; andnorthwestern California.

Potential future earthquakes

Four enclosed maps show potential peak ground accel-erations (pga) for deep earthquakes centered beneathseveral Cascadia locations. PGA is one measure ofshaking, which can help forecast areas of damage.

Local soil conditions and building vulnerability alsoinfluence the amount of damage.

Pender Island, British ColumbiaThe heaviest damage is likely to be concentrated onVancouver Island and along the Strait of Georgia.

Everett, Washington

Much of the Puget Sound area would be at risk.

Beaverton, OregonThis earthquake could destroy many URMs in thegreater Portland-Vancouver (Washington) area.

Northwestern CaliforniaDeep earthquakes here contribute a significant hazard

between Cape Mendocino and southernmost Oregon.

Lessons for the future

The Nisqually earthquake showed that mitigating haz-ards before an earthquake can pay off. Homeownerswho reinforced their chimneys were spared having torepair or replace them. Companies in upgraded build-ings and with effective contingency plans were able tocontinue their operations. Post-disaster recovery starts

before the earthquake hits, with preparation and miti-gation plans. Steps for earthquake planning:

Take care of people first. Prepare a family plan.Businesses and governments must help their em-

ployees stay safe and know their families are safe.Learn about your local earthquake hazard.

Have a response plan and practice it.

Assume that utilities and transportation lines maynot be available immediately after the shaking.

Know where the most vulnerable buildings andother structures are and work with others to devel-op and implement plans to strengthen them.

Executive Summary


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CREW Deep Earthquakes in Cascadia, 2008 1

Why deep earthquakes matter

Deep, shallow (or crustal), and subduction zone earthquakes each initiate in a dif-ferent section of the Earths interior, as shown above. The frequent occurrence andwidespread effects of deep earthquakes means everyone should prepare for them.Map: United States Geological Survey (USGS)

The Cascadia subduction zone stretches800 miles (1,300 km) from the Brooks Pen-insula, Vancouver Island to Cape Mendoci-no, California. As the Juan de Fuca andGorda plates descend beneath the NorthAmerica plate (red hachured line), activegeologic processes affect the entire over-lying region. Map: Oregon Department of

Geology and Mineral Industries (DOGAMI)

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f you live in Cascadia, youll probably experiencea serious, damaging earthquake in your lifetime.Scientists estimate that within 50 years, theres an84% chance of a magnitude (M)6.5 or higher deep

earthquake occurring in the Puget Sound region. Theodds are less for Oregon and northern California, butstill significant.

This means every person, every business, and everyorganization in the region is nearly guaranteed to facethe consequences of a deep, damaging earthquake.Such earthquakes strike, on average, every 30 years,with the latest in 2001, 1965 and 1949. Several of themare reviewed later in this paper.

On February 28, 2001, Puget Sound was rocked by anM6.8 deep earthquake centered about 30 miles (50 km)

beneath the surface. It was felt from British Columbia

to Utah, though the property damage was largelyconfined to western Washington. Building walls crum-

bled, bridge supports cracked, and the cost ultimatelyreached $4 billion. More than 400 injuries resulted, butfortunately, only one death.

While not the largest earthquakes expected in Casca-dia, the frequency of deep earthquakes makes themparticularly important. If you live west of the CascadeRange, preparing for a deep earthquake will minimizethe effects on you and the region when all types ofearthquakes occur.

Earthquake characteristicsThree source zones produce earthquakes inCascadia. Deep events start below the interface

between the subducting Juan de Fuca andGorda plates and overlying North Americaplate. A second zone lies within the crustof the overlying North America plate;this hosts shallow earthquakes like the1994 Northridge, California event. Thethird zone is on the interface betweenthe subducting plate and the NorthAmerica plate. Because of its greatextent, it can break over an enor-mous area, causing chaos acrossall of Cascadia. Each type exhibitsa specific set of characteristics.

Deep earthquakes

Deep earthquakes take placewithin the oceanic plate as itdescends, or subducts, beneaththe North America plate. Several


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terms are used to describe these events, including slab,intraslab, intraplate, subcrustal, Wadati-Benioff zone,and Benioff zone earthquakes.

Deep earthquakes in Cascadia exhibit a specific set ofcharacteristics:

They occur on faults within the subducting Juan deFuca plate. (Beneath northwestern California, deepearthquakes occur within the Gorda plate.) Beneath

Puget Sound, deep earthquakes occur at depths ofabout 30 to 50 miles (80 to 45 km); beneath north-western California the depths are somewhat shal-lower, on the order of 25 miles (40 km).

They are usually less than M7.5.

Damaging deep earthquakes occur every 10-30years in Puget Sound, less frequently elsewhere.

Because the faults that break during the earthquakeare so deep, the seismic wave energy they radiatespreads over a much larger area than in a shallowquake. A larger area experiences significant shak-ing, although much less so directly above the fault,

than in a similar-sized shallow quake.Few, if any, aftershocks occur.

No tsunami is expected, although landslides couldtrigger local tsunamis.

In the past 150 years, most damaging deep earth-quakes have been in the Puget Sound area. Recentexamples include the 2001 Nisqually (M6.8), the1965 Seattle (M6.5), and the 1949 Olympia (origi-nally measured M7.1, now revised to M6.8) earth-

quakes in Washington.

Shallow earthquakes

They occur within the continental crust of the over-lying North America plate, generally at depths ofless than 20 miles (35 kilometers).

They are expected to be less than M7.5.

Because of the abundance of shallow faults, smallearthquakes are recorded every day in Cascadia.The presence of these faults directly under the sur-face, sometimes in populated areas, means thatdamaging shallow earthquakes occur every fewdecades. Any specific fault may produce an earth-quake every few hundred years or every few thou-sand years.

Strong shaking generally lasts a few seconds to aminute or so, although it could be longer in local-ized areas.

Aftershocks are common and may cause furtherdisruption.

Tsunamis are unlikely, though there could be a lo-cal tsunami from landslides, or from shallow earth-quakes occurring under Puget Sound, the Strait ofGeorgia, or large lakes and rivers.

In 2005, the Earthquake Engineering Research Insti-tute and the Washington Military Department publisheda scenario for an M6.7 earthquake on the Seattle Fault(which would be a shallow event). The report was writtenby an interdisciplinary team of scientists, engineers, andemergency managers from throughout the region.

The map above shows the approximate location of thefault trace on the surface (white line), along with areas(in red) that would likely suffer the greatest damage.Peak ground accelerations (pga) of .10g to .20g could

cause slight damage, with major damage occurring athigher pga values. Map: USGS


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Several significant Cascadia earthquakes were shal-low, including the 1946 Vancouver Island, BritishColumbia (M7.3), 1993 Scotts Mills, Oregon (M5.6),and 1954 Eureka, California (M6.5) events.

Subduction earthquakes

The Juan de Fuca and Gorda plates (offshorenorthern California) descend, or subduct, beneaththe North America plate. Large areas of the inter-

face between the two plates act as if stuck, caus-ing stresses to build. Eventually the stresses reachthe breaking strength and the two plates slip rapid-ly, releasing the stresses. Huge areas may slip, gen-erating very large earthquakes that radiate strongseismic waves throughout Cascadia.

They can be as large as M9.

Geological evidence suggests an average of 500years between events.

Depending on location, strong shaking might befelt for several minutes.

Injuries and fatalities could number in the thousands,and hundreds of buildings could be destroyed.

Many aftershocks will occur; some in the M7 rangeare possible, creating the potential for additional

damage.

A destructive tsunami will quickly hit the Cascadiacoast, and travel across the Pacific Ocean towardAlaska, Hawaii, and Asia.

The last Cascadia earthquake occurred on January26, 1700. Previous quakes were in the years (ap-proximately) 900, 750, and 400.

Similar magnitude, different outcomes

A comparison of the effects of the Nisqually earthquakeand those of the 1994 event in Northridge, California(M6.7) illustrates the differences between deep andshallow earthquakes. The smaller, shallow (11 miles or17 km deep) Northridge event caused 72 deaths andeconomic damage of more than $12 billion. The deepNisqually earthquake produced only one death andlosses of $4 billion. Although Northridge was a moredeveloped area, part of the difference was due to thedifferent source regions of the earthquakes.

The Nisqually earthquake occurred when a deep fault

broke, radiating seismic waves as the two sides of thefault slipped several feet within a few seconds. Becausethe waves originated from such depth, they traveledfarther to reach the surface, losing energy along theway, and spreading out laterally. As in all deep earth-quakes, the area directly above the epicenter felt lesssevere shaking than from a shallow earthquake of thesame magnitude, but the shaking affected a larger areaoverall.

These maps compare the intensity of shaking felt in the2001 Nisqually earthquake (above) and the 1994 North-ridge earthquake (below).

The distance and intensity scales of the maps are identi-cal. The deep earthquake at Nisqually shows a wide areaof potential damage, but Northridge shows a concentra-tion of heavier damage near the epicenter.


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ShakeMaps, maps of shaking intensity generatednearly instantly, help emergency responders, andprovide a basis for assessing region-wide damage, aswell as providing public information in the aftermathof a large earthquake. ShakeMaps are automaticallyproduced by computers receiving measurements ofactual shaking levels from continuously operatingmonitoring instruments.

Comparing the maps on page 3 from the M6.8 Nisquallyand M6.7 Northridge events shows the difference

between deep and shallow events. The ShakeMapshave identical distance and intensity scales. Intensitymeasures the effects of an earthquakes, which can

be estimated from the ground motions recorded bymonitoring instruments in the region. It is differentthan magnitude, which directly measures the size ofthe earthquake; that is, it measures a characteristic ofthe earthquake itself, not its effects.

Shallow earthquakes like Northridge cause destruc-tion near the epicenter, evident in the larger, but

concentrated red area on the Northridge ShakeMap.However, the yellow area, indicative of light damage,is more widespread on the Nisqually map than theNorthridge map. Shallow earthquakes commonly havenumerous aftershocks, which can cause more damage.Deep earthquakes have few, if any, aftershocks.

What kind of earthquake should youprepare for?

In the Puget Sound area, as mentioned above, thechances of a deep earthquake larger than M6.5 in thenext 50 years is 84%. The chances are 15% for a shallowevent, and 10-14% for a subduction earthquake. In your

area, the exact percentages for each type of event maydiffer, but damage from a deep earthquake should beconsidered.

Preparations can reduce earthquake damage. Repairsto homes, offices, schools, and other buildings can beexpensive. Earthquake insurance deductibles are typi-cally high. After a large event, federal funds may beavailable, but they may be in the form of loans, or maynot cover your entire loss. Many small businesses thatclose because of an earthquake never reopen.

Whatever measurers you take will also prepare youfor the other two types of earthquakes. In addition topreparing your own home and having an emergencyplan, earthquake hazard reduction calls for regionalplanning and preparation. Individuals and companiescan be part of broader discussions about what needs to

be done and how to do it.

This photo of a building in Olympia after the2001 Nisqually earthquake shows typical dam-age from a deep earthquake. A major source of in-

jury is falling parapets, such as those seen above.Photo: Josh (Robert) Logan, DGER


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Hazards in a deep earthquake

Ground shaking: Some soil types cause earthquakewaves to amplify, causing increased shaking and dam-age. The risk of amplification increases on deep, softsoils, especially on valley bottoms and areas of artificialfill. These soils can be identified before an earthquake.Most areas at risk can be identified from soil studiesdone for land use planning and development, or on

geologic maps.

Ground failure:Sandy soils saturated with water canliquefy behave like a liquid during an earthquake.Major earthquake destruction is often found on thesesoils, which are prevalent along rivers, streams, andlakes. Liquefaction can seriously damage buildings,

bridges, pipelines, and roads by undermining theirfoundations and supports.

Earthquakes can also trigger landslides. These mayhappen immediately, or can occur days, even weeks,later. The more water there is in the soil, the morelikely are landslides. Lateral spreading is a specific

type of landslide that forms on very gentle slopes. Itcan, for example, cause roadways to break up.

After shaking and liquefaction, the ground mustresettle. Differential settlement can cause structures totilt, resulting in structural and nonstructural damage.

Tsunami:Deep earthquakes do not produce tsunamisbecause they do not significantly disrupt the oceanfloor or inland waterways. Landslides could producelocalized tsunamis, but they are rare in the history ofCascadia.

Secondary hazards

Fire:Fire often destroys property after an earthquake.Ruptured gas lines may provide fuel, and broken waterlines hinder firefighters efforts. Gas lines turned offto prevent fire may not be restored for days, causingother hardships.

Hazardous materials: Hazardous materials may bespilled from commercial or industrial sources, but theycan also be released in households. Serious problemscan happen if the contents of several containers mix such as ammonia and chlorine bleach.

In addition, trucks carrying hazardous materials maybe stuck on roadways if highways and bridges have tobe closed.

Building vulnerabilities: Much damage and injury inearthquakes results from structural failures. However,we can reduce building vulnerability.

As weve learned more about the earthquake dangerin Cascadia, building codes have been upgraded. The

buildings most at risk in an earthquake include unre-inforced masonry buildings (URMs) and nonductile

Many areas of potential liquefaction have been mapped.These are among the most likely places to have damagein an earthquake. The above map shows potential liq-uefaction sites in the Kent Valley, Washington, south ofSeattle. Red shows the highest risk. Black areas are con-centrations of major buildings. Map: Washington StateDivision of Geology and Earth Resources (DGER)

Many structures, utility lines, and transportation sys-tems (road, air, rail, port) need to be inspected aftera large earthquake. Structures can be given a yellowtag, like this one, meaning it can be used to someextent but repairs must be made. A red tag meansthe structure cannot be used until it is repaired.Photo: William S. Lingley, DGER


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concrete-frame buildings. URMs are generally builtwith brick walls and wood or concrete floors that arepoorly connected to the walls. Nonductile concreteframes have very little steel reinforcement and are very

brittle when subjected to earthquake motions.

Wood-frame homes generally fare well in earthquakes.But chimneys and brick facings can collapse and win-dows can break. If not securely fastened together, a

house may separate from its foundation, disconnectingutility lines and making the house unlivable.

The design of a building, as well as construction mate-rial, also affects its vulnerability. The more square orrectangular a building shape, the more likely it canwithstand shaking. Parts of individual structures orclosely-spaced, adjacent buildings may pound againsteach other. Soft stories, such as parking levels, openretail space, and other floors with insufficient strengthare more susceptible to collapse in earthquakes.

The most common type of damage is nonstructural.All buildings can suffer nonstructural damage, result-

ing in injuries and economic losses. Falling debrislike bookshelves, light fixtures, and computers can bedangerous, even at home. Furniture moving across afloor, pipes breaking and spilling contents, and para-pets falling from buildings are just a few examples thatcan be avoided by relatively inexpensive nonstructuralstrengthening before earthquakes occur.

Mitigating nonstructural hazards is usually less expen-sive than reinforcing or rebuilding existing structures.It also can be done in stages, as resources permit. The

best time to address building structural and nonstruc-tural deficiencies is in conjunction with other planned

major renovations.

Its not over when the shaking stops

Damaged bridges, destroyed building walls, andimpassable roads are examples of obvious and imme-diate earthquake damage. Some dangers may not beimmediately apparent as in landslides that occurdays after the shaking.

Closed businesses are not just a problem for theowners, but for the employees who lose jobs and theoverall economic health of the city, which loses tax rev-enue particularly needed to cover the extra expenses

of earthquake repairs. Damaged roads, bridges, andother transportation lines can snarl traffic and delaythe arrival of supplies needed for rebuilding.

Although fortunately rare where enforced buildingcodes exist, deaths and serious injuries do occur, andtake their own toll on a community.

It is easier and less expensive to take precautionsbefore an earthquake than to experience and pay forthe cleanup after one.

Closed businesses and disrupted streets, like this oneafter the Nisqually earthquake, can be a problem for theeconomic health of communities. Photo: Robert J. Reid

This house shifted off its foundation, breaking the utilitylines and leaving it uninhabitable. Newer building codes re-quire a house being tied to the foundation, but homeownersmay need to retrot older homes. Photo: USGS


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The epicenters of several Cascadia deep earth-quakes during the last hundred years were inthe Puget Sound region. However, they canalso be centered under British Columbia (an

M5.6 earthquake in 1909 off Vancouver Island caused

damage in British Columbia and Washington), Oregon,and California.

Their frequent occurrence, the high population densityin the areas likely affected, and the damage pattern ofthese events, means all of Cascadia needs to be awareof deep earthquakes.

Looking at the past helps us understand what the nextearthquake might look like, keeping in mind that deepearthquakes provide relatively gentle reminders of theinevitable, but less frequent, catastrophic subductionzone earthquakes that loom in Cascadias future. The2001 Nisqually earthquake, the most damaging recent

event in Cascadia, is described in a separate section.

1949 Olympia

A deep earthquake at 11:55 AM on April 13, 1949 wascentered between Olympia and Tacoma, along thesouthern edge of Puget Sound. The original magnitudeof 7.1 has been revised to M6.8. It was felt from BritishColumbia to Montana to California.

Eight people were killed and dozensseriously injured. Two of the dead werechildren: one was crushed by falling brickwhile working as a crossing guard and

one was the senior class president at CastleRock High School.

Olympia, Seattle, and Tacoma incurredproperty damage estimated at $200 million(in 2006 dollars). The most severe damagewas centered between Seattle and Cheha-lis, with 40% of Chehalis business build-ings and houses damaged. About 10,000chimneys in Western Washington neededrepair.

Thirty Washington schools, normallyserving 10,000 students, were damaged in

1949. Ten of these schools were condemnedand permanently closed Three Seattleschools were torn down and one rebuilt.Fortunately the 1949 and 1965 earthquakesoccurred during spring vacation, sparingmore school children from fatalities andinjuries.

In Olympia, almost all large buildings were

Recent deep earthquakes

Chimney failures are a common problem for homeown-ers after an earthquake. The above chimney did not

fall but remained a safety hazard until it was rebuilt.Photo: Michael Polenz, DGER

The Long Beach, California school above shows how dangerous old, brickbuildings can be. In the 1949 Olympia earthquake, the Senior Class Presi-dent of Castle Rock High School was killed by falling bricks. The gable onthe school collapsed, even though the structure was more than 50 miles(80 kilometers) from the epicenter. Photo: USGS


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damaged to some extent, including eight struc-tures on the Capitol grounds. Water and gasmains broke, and electric and telegraph serviceswere interrupted.

In Tacoma, many chimneys were knocked tothe ground and many buildings were damaged.The Tacoma Narrows bridge sustained damage.South of Tacoma, railroad bridges were thrown

out of alignment.

In Seattle, houses on filled ground were demol-ished, many old brick buildings were damaged,and chimneys toppled. Because of old construc-tion and unstable ground, most buildings inPioneer Square received some damage.

Water spouted from cracks that formed in theground at Centralia, Longview, and Seattle. Onenew spring developed on a farm at Forest.

1962 Corvallis

At 7:45 AM on September 1, 1962, an M4.5 deepevent struck northwest of Corvallis. Because ofthe earthquakes small size, there was no dam-age. However, it does demonstrate that Oregonis at risk from deep earthquakes located insideits own borders, as well as from those centeredin Washington and California.

1965 Seattle

At 7:28 AM on April 29, 1965, an M6.5 earth-quake struck very near the 1949 epicenter. Itkilled seven and caused damage of $100 million(in 2006 dollars).

Falling debris killed three people: one on SouthKing Street in Seattles Pioneer Square and twoat Fisher Flouring Mills on Seattles HarborIsland. Four elderly women died from heartfailure attributed to the earthquake.

In general, damage patterns repeated thosefrom the 1949 shock. Some buildings damagedin 1949 sustained additional damage in 1965.One example is the Alki Beach section of WestSeattle, where a majority of chimneys wereknocked down in 1949, and again in 1965.

The greatest devastation in 1965 occurred inWest Seattle, Harbor Island, the DuwamishRiver Industrial Area, and South Seattle.Numerous bridges were damaged along theDuwamish Waterway and River blocking boattraffic along the river. Failures affected virtu-ally every building, pier, and facility at HarborIsland and along the Seattle waterfront.

Landslides are an often-overlooked danger of earthquakes. They areparticularly likely during rainy, water-soaked winter months in Cas-cadia. Almost 40 miles (60 kilometers) from the epicenter, this sec-tion of the Union Pacic Railway was left dangling after the hillside

ll beneath it slid away in the 1965 earthquake. A sewer main also

broke. Photo: University of California, Berkeley

During the April 1949 earthquake, the owner of the Busy Bee Cafe

barred the doors to keep panicking patrons from rushing outside.Seconds later, brick fell from the top of the Hotel Seattle, crushingseveral cars. Photo: Seattle Post-Intelligencer Collection, Museumof History & Industry; All Rights Reserved


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In Tacoma, damage occurred mainly to cornices andchimneys of older structures built on soft ground inlowland areas and on firmer gravel in highland areas.

In Olympia, damage was primarily confined to the oldpart of the city and to areas of the port built on artificialfill. The State Capitol Building was temporarily closedand government departments moved to nearby motelswhile buildings were being repaired.

Eight Seattle schools normally serving 8,800 studentswere closed until safety inspections could be carriedout.

In general the most vulnerable buildings were thosehaving unreinforced masonry walls with sand-limemortar. Wood-frame houses came through quite well,although a few had cracked plaster or chimney failures.Split-level homes fared worse because the two sectionsof the houses vibrated at different frequencies, concen-trating stress along the junction between the sections.

1976 Pender Island

At 1:35 AM on May 16, 1976, an M5.3 earthquake, about40 miles (70 km) deep woke the residents of PenderIsland (to the east of Vancouver Island).

The earthquake jolted people awake and even knockedpeople out of their beds in White Rock. The LowerMainland and southern Vancouver Island sustainedslight damage. Banks alarms rang out, windows broke,and dishes rattled in Victoria. Electrical service wascut in Richmond, South Vancouver, and the SecheltPeninsula.

Although small and without significant consequence,

this earthquake provides an important reminder ofthe risk that local deep earthquakes pose to BritishColumbia.

1999 Satsop

A M5.9 earthquake shook the Pacific Northwest on July2, 1999, at 6:44 PM. It was centered beneath Satsop, justwest of Olympia, and felt from British Columbia toIdaho to Oregon.

The most visible damage was to the Grays HarborCounty Courthouse in Montesano, an unreinforcedmansonry building from 1910. The cupola atop a clock

tower was extensively damaged, and interior wallsshowed new cracks. Total damage to county buildingswas estimated at $10 million.

The Montesano fire station, built around 1979, alsosuffered structural damage. A number of other fire sta-tions in the county were damaged.

Falling walls are not necessary for injuries to occur.Kitchens can be a place of major nonstructural dam-age. Glassware, dishes, and food containers can fallfrom shelves. Cleaning supplies can fall off shelvesand break. Mixing of some chemicals, like chlorinebleach and ammonia, can produce serious hazards.Photo: P. W. Weigand, California State University at

Northridge


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O

n February 28, 2001 at 10:54 AM, an earth-quake measuring M6.8 was centered nearthe Nisqually delta north of Olympia. Itshook Puget Sound and beyond. One per-

son died from a stress-induced heart attack and therewere 400 injuries, including 27 head injuries fromfalling brick. After the shaking stopped, 40,000 peopleapplied for FEMA assistance. Damage was estimatedat $4 billion. Only 10% of that was insured.

The earthquake caused evacuations from Victoria toOregon (along the coast and in the mid-Willamette Val-ley), and was felt as far away as Salt Lake City, Utah.

The damage pattern showed the importance of localsoil and geological conditions. Seattle and Olympiahad numerous damaged buildings. Although Tacomasits between these two cities and did suffer some dam-

age, as detailed in sections below, it was substantiallyless affected than the other metropolitan regions. Thisis clearly shown on the intensity map on page 3.

Damage to buildings

Most of the property damage occurred very nearthe epicenter in Olympia; in nonductile concrete ormasonry (URM) buildings, such as those in the PioneerSquare and SODO neighborhoods of Seattle; and inareas of poor soils, such as near Sea-Tac Airport. Repairsto more than 350 historic buildings in Washington costan estimated $50 million. Nonstructural damage wasextensive, though generally not life-threatening.

Even in these areas, however, there were success sto-ries. The SODO Center building, home of Starbucks,originally built in 1914 and expanded over the nextfew decades, sustained little structural damage. The

building owner had retrofitted the structure to improveseismic performance and Starbucks had extensive con-tingency planning in place. Although operations hadto be temporarily relocated, its business was able tosustain the interruption

The Capitol building in Olympia had to be closedfor over three years because the dome shifted. It hadpreviously been damaged in 1949 and 1965. Other

buildings on the Capitol campus were also closed forrepair. Damage forced Washingtons Governor GaryLocke to move out of the Governors Mansion, and hereported watching their television bounce off its shelf,nearly hitting his young son. In all, 27 buildings wereclosed in Olympia.

URMs in Olympia and Seattle were hit hard. Severalbuildings had wall collapses and more than a thousand

2001 Nisqually

Earthquake retrots and other preparations paid off

at the SODO Center for Starbucks. They were ableto sustain the interruption due to the earthquake.Photo: A. Sanli and M. Celebi, USGS; and S. Akkar,METU, Turkey

A Community Internet Intensity Map for the Nisquallyearthquake was immediately generated online by theUSGS. An Internet survey asked people to record wheth-er they felt the earthquake and how strong it was. Theresults are displayed by zip code area. The earthquakewas felt outside the area shown on this map, but thisshows where it was most intense.

The red star shows the epicenter, and colored areas onthe map indicate the intensity, as described in the key.Map: USGS


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were red-tagged (too dangerous to remain open) oryellow-tagged (seriously damaged and only partiallyusable). The most common damage was cracking orpartial collapse of walls and loose bricks from fallingparapets and chimneys. More than 300,000 buildingswere damaged. After one year there were still 17 red-tagged buildings and 204 yellow-tagged.

Wood-frame and more modern constructed buildings

performed well. However, downtown Olympia andselect neighborhoods around Seattle had heavy chim-ney damage, usually the most vulnerable part of woodhouses. In west Seattle, areas suffering damage in the1965 earthquake experienced a high rate of chimneydamage. Damage was also concentrated along theSeattle fault zone.

In Seattle, 75 schools reported mostly light damage.The Seattle School District had focused on nonstruc-tural upgrades that undoubtedly prevented injuries.Typical projects had secured items such as bookcases,library shelves, ceiling light fixtures, wall-mounted

speakers, computers, and vending machines.All hospitals in the area stayed open, though some hadnonstructural damage. One Seattle hospital spent $3million in repairs, having to replace 85 seismic joints.In Steilacoom, south of Tacoma, a building at WesternState Hospital was red-tagged, so the staff had to trans-fer patients to another ward.

A fire station in Ashford, east of Tacoma, was red-tagged because of severe cracking.

New buildings built to updated building codes orto structures retrofitted to current standards fared

well, although even they experienced nonstructuraldamage.

Minor damage was found as far away as Victoria, Brit-ish Columbia, including broken pipes and windows,and small cracks in walls.

Shelter

The American Red Cross opened seven shelters on theday of the disaster. Four days later they were all closed.The scant need for shelter may be connected to thetype of buildings damaged, most being commercialand governmental properties. Only about 200 homes

and apartments were seriously damaged.Small business losses

The Small Business Administration granted 6,253 low-interest loans, totaling $834 million. They approved61% of applications to the program.

A University of Washington survey taken after theearthquake found that 75% of the business owners

Successful preparation:

Project ImpactThe damage in Seattle could have been muchworse without the seismic upgrades made

just before the earthquake.

Project Impact, a now discontinued FederalEmergency Management Agency (FEMA)program, was intended to help communitiesreduce future damage from earthquakes. Itworked quite well in Seattle.

Seattle Emergency Management provided

overall project coordination and fund man-agement of its $1 million Project Impactgrant, which was completed in 2001. City ofSeattle has institutionalized Seattle ProjectImpact and we are committed to continuingthese efforts well into the future, includingmanaging additional grants and regionalpartnerships.

Over the life of the Project Impact grant,approximately half of the money was spenton the Home Retrofit program, the overall

goal of which is to encourage homeowners tostructurally retrofit their homes. Seattle Pub-lic Schools received most of the remainingmoney for non-structural Schools Retrofit.The last component of the grant supportedbetter Hazard Mapping.

From the Seattle City website. For moreinformation, go to:http://www.seattle.gov/emergency/programs/projectimpact.


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surveyed paid for damages out of their own pocket,without insurance or government loans.

Roads

Most damage to roads was because of liquefaction andlandslides.

The northbound lanes of US 101 west of Olympia slidaway during the earthquake and were closed until adetour was established.

Two lanes of I-405 in the Renton area buckled becausethe earthquake rerouted groundwater, which thenpressed against the surface of the freeway.

The Deschutes Parkway in Olympia closed for morethan a year. Liquefaction of fill under the Parkwaycaused part of the road to slide into Capitol Lake. Solidfill materials were added to the roads foundation tocompensate for the high water table in the area, but itmay not be a permanent solution. Repairs totaled $5million.

A landslide caused significant damage to five houses,as well as the roadway, on Maplewild Avenue inBurien, which was built in the 1930s on a steep slope.Repair costs exceeded $7 million. Because Maplewildis a Federal Arterial, it was eligible for $6.6 million infederal aid.

On SR 202 near Snoqualmie Falls, the shoulder fellaway about six inches and a 900-foot long crack devel-oped in the road.

SR 302 east of Allyn had a quar-ter-mile stretch where the lanesdropped several inches and leftsignificant cracks in the pave-ment. Repairs cost $1.4 million.

Bridges

Washington State Departmentof Transportation (WSDOT)inspected nearly a thousand

bridges, finding damage, mostlylight, at 40 of them. The City ofSeattle reported mostly lightdamage to 22 other bridges,and other counties around the

epicenter found similar dam-age. Very few bridges, mainlyamong those built before 1980,had to be closed for an extendedtime.

Undoubtedly this successreflects an extensive retrofit pro-gram, implemented during the

Liquefaction, lateral spreading, and landslides damaged many roads throughout thearea. Photo: William S. Lingley, DGER

The South Park Bridge in Seattle suffered extensivedamage. Above is one of 22 columns that crackedin the earthquake. Epoxy was injected to shore upthe structure. Crews worked round the clock to re-pair this and other structures throughout the area.Photo: King County


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decade before the earthquake, thatupgraded many bridges. Three inSeattle (the Ballard, Fremont, andUniversity bridges), each morethan 80 years old, were seismicallyretrofitted before the earthquake,and escaped damage.

Seattle

The Alaskan Way Viaduct alongthe waterfront was (and remains)a great concern after the earth-quake. WSDOT made $3.5 millionin immediate repairs to keep itfunctional and began semi-annualearthquake inspections to closelymonitor cracks, structural move-ment and foundation integrity. Along-term plan for this structureis still being developed, with anyreplacement costs certain to be in

the billions of dollars.The Magnolia Bridge was closedfor nearly four months. Immedi-ate repairs cost $3 million, but thespan is due to be replaced becauseof its age. Funding has not yet beenidentified, but Seattle is hoping tostart construction in 2009.

The Holgate Street overpass overI-5 was closed a few days.

The SR 99 Spokane Street Viaduct

was closed briefly due to minordamage to existing seismic retrofitfeatures.

The 1st Avenue S. Drawbridge onSR 509 had minor damage thatcost $500,000 to repair.

The eastbound on-ramp to Inter-state 90 at 4th Avenue S. experi-enced minor cracks.

Olympia

The Fourth Avenue bridge, built

in 1920 and retrofitted in 1949,was severely damaged and closed.Even before the earthquake it had

been scheduled for replacementand upgrade to current seismiccodes. It is now part of the 4th/5thAvenue Bridge and Corridor. The$37 million project included awider bridge, with three vehicle

Olympias Fourth Avenue Bridge was closed after the earthquake be-cause of severe damage (above). The rebuilt structure (below) is an as-set to the community, not only because of its aesthetics, but becauseit was designed for pedestrians and bicyclists as well as automobiles.Above photo: Robert J. Reid; Below photo: Timothy J. Walsh, DGER


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lanes, plus sidewalks and bike lanes on both sides.

The I-5 Capitol Lake Bridge suffered minor damage.

The I-5 Capitol Way Bridge had damage to existingseismic retrofit features.

Tacoma

The Tacoma Narrows Bridge needed minor repairs.

The bridge is undergoing a complete retrofit, to becompleted in 2008.

The SR 509 bridge (11th Street) was unable to open forships until repaired.

Other

Three days after the earthquake, 25 bridgesin the area were still closed for repair orinspection. One was over I-5 near Chehalis,where the railroad overcrossing was seri-ously damaged and needed emergencyrepairs costing $550,000. Other bridgesnear Centralia, Morton, and Kalama wereclosed briefly to vehicles.

Airports

At Sea-Tac, the tower was damagedseverely enough to reroute air traffic toPortland and Spokane for several hours.By the end of the day, 50% of traffic wasrestored to Sea-Tac. The tower itself sus-tained structural damage. There was alsosignificant nonstructural damage.

Boeing Field is part of the King CountyAirport and is home to cargo carriers andcivil aviation, as well as being a supportfacility for Boeings final manufacturingoperations. Liquefaction caused gaps inthe runway, closing the airport for a week.Boeing sent 90,000 workers home the dayof the quake.

Railroads

The earthquake disrupted Amtraks train servicebetween Portland and Seattle, and on another linebetween Seattle and Los Angeles.

Ports

Seattle is the fifth largest US container port, so anydisruption is potentially serious. Cargo handling was

briefly suspended until inspections were completedand showed no damage. As expected in areas withsoft soils, there were sand boils, lateral spreading,and water line breaks, but none of them interruptedservice.

The tower at Sea-Tac sustained both structural and nonstructural damage.Even so, the airport was able to reopen after a few hours. Photo: Washing-ton State Department of Transportation


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Tacoma is the sixth largest container port.The Port of Tacoma had some buckledpavement and structural damage to three

buildings, largely because of liquefaction.

Power

Immediately after the earthquake, 200,000customers in South King, Pierce, and Thur-

ston counties lost power. Within six hours,only 8,000 customers remained withoutpower. No damage was reported to theelectrical power generation and distribu-tion systems.

Water, sewer, and gas lines

Although there were several water mainbreaks throughout the area, water supplieswere not disrupted.

In Victoria, a broken water main in southOak Bay flooded six homes.

One gas line and several water lines wereruptured in Tumwaters Mobile Estate Park.

At the Cedar Creek Correctional Centernear Olympia, an explosion on a natural gasline injured two workers.

On Harbor Island in King County, there wasa 1,300 gallon spill of diesel and gasoline.

Fire is often a major concern after an earth-quake because of broken gas lines and thedifficulty of fire fighting with broken watermains. However, only one fire was reported,

a building in Seattle.

Communications

Telephone lines both landlines and cellphones were jammed immediately afterthe earthquake. According to US West,60 million calls were initiated in WesternWashington on the day of the quake. Theoverall number of calls for the 24-hourperiod was at least six times normal. In thefirst 24 hours after the earthquake, AT&Trejected seven million calls from outside the

area.On the afternoon of the earthquake, MSNreported five million more emails thannormal.

In general, the 800 MHz public safety radiosystem worked well, but not all jurisdic-tions had it. The system was overwhelmedin King County and was only partly func-tional the day of the earthquake.

Salmon Beach, near Tacoma, was the site of a landslide three days af-ter the 2001 earthquake. The same hillside slid after the 1949 event.Photo: Dave Sherrod, USGS

Liquefaction and landslides can break utility lines as well as damageroads and property. With widespread damage, repairs may take longerthan expected. Photo: Robert J. Reid


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Dams

Washington state engineers inspected almost300 dams and only five were damaged. Allfive had previously been identified as poten-tial problems. Inspectors from the FederalEnergy Regulatory Commission, the Bureauof Reclamation, and the US Army Corps ofEngineers found no damage to the dams they

regulate.

Landslides

Damage from earthquake-induced landslideswas estimated at approximately $34 million.Hundreds of landslides occurred, though notall with damage. Landslides were mappedfrom British Columbia to Portland, Oregon,

but were concentrated in the Puget Soundarea. The large events described below werenot included in the road damage or other sec-tions above.

Salmon Beach (near Tacoma)

Repair costs were estimated at $1.5 million. The slidedemolished two houses at the base of the slope; eightother houses were red-tagged because of danger fromslide material still above them. The slide occurred threedays after the earthquake, as the result of the cliff beingweakened from shaking.

Salmon Beach was also the site of an enormous land-slide after the 1949 landslide. Damage then includedsmashed boats, dock areas, and a wooden boardwalk.

Deschutes Parkway (Olympia)

Besides the road damage to the Deschutes Parkwaydescribed above, several lateral-spread landslidesaround the margins of Capitol Lake created a signifi-cantly larger problem. Water and sewer lines crossingthe area broke in places. The cost to repair landslidedamage to Capitol Lake, Marathon Park, and DeschutesParkway was estimated at approximately $22 million.

Cedar River (near Renton)

Landslides caused damage costing nearly $2 millionto fix. One slide blocked the Cedar River and createda reservoir until the debris could be moved. Part of

a flood-erosion control facility was destroyed. Twohouses and considerable land were flooded upstreamof the temporary dam.

A second landslide just upstream of the dam slammedinto a house. A woman ran out of her home and barelyavoided being buried by the debris that filled herkitchen.

A landslide dammed the Cedar River, resulting in ooding that damaged

two houses. Photo: King County


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Future Deep EarthquakesNot the Big One, but big enough to matter

What follows are four maps that show how deepearthquakes could affect various parts of Cascadia.Four epicenters are discussed: Everett (north of

Seattle), Washington; Pender Island (off southeasternVancouver Island), British Columbia; Beaverton (westof Portland), Oregon; and northwestern California.

For each area, the map shows the extent of expectedground shaking. This will help local authorities under-stand how a large, deep earthquake could affect theircommunities. (Note: Earthquakes centered under otherlocations are also possible.)

Ground shaking strength is measured in terms of peakground acceleration (pga). Higher pga generally resultsin more damage. The effect of any earthquake willdepend on the distance to the epicenter, how deep itis, soil types, and building types. PGA is used because

building codes prescribe how much horizontal force,or acceleration, a building should be able to withstandduring an earthquake. The force we are most experi-enced with is due to gravity, so pga is expressed as apercent of gravity.

These maps are broad generalizations of the expectedshaking patterns, and do not include the effects ofvariations in local soil types. In many areas, the pgawill be higher than indicated. A pga of approximately.10 to .20 can cause damage in unreinforced masonry

buildings (URMs) on soft soils. A .20 pga can trigger

landslides on steep slopes with saturated soils.

URMs are old brick or masonry buildings that have notbeen upgraded to current earthquake codes. Thoughthese are among the most dangerous places to be in anearthquake, they can be retrofitted for greater safety.

These maps can be used as inputs in HAZUS, a modeldeveloped by the Department of Homeland SecurityFederal Emergency Management Agency (FEMA)to forecast earthquake damage and losses. Maps offorecasted pga are input to HAZUS, which producesestimates of potential damage to buildings, utilitiesand roadways, and more, as well as forecasts for inju-ries at various times of day. HAZUS can be used as astarting point for earthquake preparation and responseplanning.

Some previous deep earthquakes are recapped earlier,starting on page 7. These give you an idea of the kindof damage and losses that can be expected in futuredeep earthquakes.

Reading the maps

1. What is acceleration?

Acceleration is how much velocity changes overtime.

Consider a car increasing in speed from 0 to 60mph (see metric units below). 60 mph is 88 feetper second (s). If the acceleration is constant,then the car reaches a velocity of 88 ft/s in 8seconds. The velocity changes by 11 ft/s everysecond, so the acceleration is 11 ft/s/s.

In metric units, consider a car increasing in speedfrom 0 to 97 kph. 97 kph is 27 meters per second(s). If the acceleration is constant, then the car

reaches a velocity of 27 m/s in 8 seconds. Thevelocity changes by 3.4 m/s every second, so theacceleration is 3.4 m/s/s.

If the acceleration were not uniform, but startedsmall then increased, the highest value of accel-eration would be the peak acceleration.

2. What is peak acceleration as a measure ofearthquake ground motion?

All particles comprising the Earth and objectssitting on its surface move back and forth irregu-larly as earthquake waves pass through them.

The rate at which this movement changes can bedescribed by its acceleration. Peak acceleration isthe maximum reached during the passage of theearthquake waves.

3. What is percent of gravity (%g)?

We experience acceleration as a force (as in amoving car). The force we are most experiencedwith is due to gravity. The units of acceleration onthe map are measure in terms of g, the accelera-tion due to gravity. This factor g has a value of 32ft/s/s (9.8 m/s/s).

For the car example above, an acceleration of 11ft/s/s (3.4 m/s/s), divided by g, is 34%g or 0.34g.

Modified from the USGS Earthquakes Hazards Pro-grams definitions. For more information on pga andhow it affects buildings, see http://earthquake.usgs.gov/research/hazmaps/haz101/faq/faq.php.


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The above map shows potential pga for an M6.8 deepearthquake under Everett, Washington. This map does notinclude the variations in soil types, topography, and sub-surface geologic structure that may increase or decreaseshaking and damage locally. Much of the Puget Sound areawould be at risk for damage. Because the epicenter is un-der a more developed area than the Nisqually earthquakewas, the damage is likely to be worse. The shaking itselfwill be felt beyond the edges of this map. Map: Art Frankel,USGS

The above map shows potential pga for an M6.8 deep earth-quake under Pender Island, British Columbia. This map doesnot include the variations in soil types, topography, and sub-surface geologic structure that may increase or decreaseshaking and damage locally. The heaviest damage is likelyto be concentrated on Vancouver Island and along the Straitof Georgia. The shaking itself will be felt beyond the edges ofthis map. Map: Art Frankel, USGS


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The above map shows potential pga for an M6.5 deepearthquake under Beaverton, Oregon. This map does notinclude the variations in soil types, topography, and sub-surface geologic structure that may increase or decreaseshaking and damage locally. This earthquake could pose asignicant risk to many URMs in the greater Portland area.

The shaking itself will be felt beyond the edges of this map.Map: Art Frankel, USGS

The above map shows potential pga for an M6.8 deepearthquake under northwestern California. This mapdoes not include the variations in soil types, topography,and subsurface geologic structure that may increase ordecrease shaking and damage locally. The shaking itselfis likely to be felt beyond the edges of this map. Deepearthquakes beneath northwestern California contributesignicant hazard to the coast between Cape Mendocino

and southernmost Oregon. Map: Art Frankel, USGS


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Lessons for the future

Preparation dramatically reduces injuries,deaths, and property loss from earthquakes.What are the most important preparations wecan make before the next earthquake?

Individuals and families can take basic steps likeassembling emergency kits, making their homes earth-quake resistant, and having a family communicationplan. Governments, utilities, and businesses must alsomake plans to protect and support their staffs. In addi-tion, they will need to have preparedness plans andhave implemented mitigation measures.

Extensive work has been done on how to prepare forfuture earthquakes. You can take advantage of thisknowledge as you plan to reduce future damage inyour own community. The websites on page 22 are agood place to start your research.

Start with peopleWhether youre responsible for a family or a multina-tional corporation, your preparedness plans and miti-gation measures should start with protecting people.Employees cannot focus on the work you need themto do unless they are safe and they know their lovedones are safe.

Family emergency plans are easy to put together.In general, they include where the family membersshould meet after an earthquake (driving may bedifficult because of jammed roads) and how theycan contact each other (a central phone number,

preferably outside Cascadia). Many organizationshave templates.

Learn to drop, cover, and hold, and know the evac-uation routes out of your homes, offices, or schools.Drills can be held periodically. Provisions should

be made for those with disabilities.

Whether youre responsible for a family, a school,a workplace, or an entire region, an emergency re-sponse plan is a must. It should be flexible enoughto put into place with whoever is available duringthe earthquake, but detailed enough so that peopleknow what is expected of them. It must be prac-ticed.

Three-day emergency kits can be stocked, kept cur-rent, and placed to be easily grabbed when evacu-ating.

Know your earthquake hazard. Become educatedabout the earthquake hazard where you live, work,or go to school. Many local or state jurisdictionspublish maps that show the hazard in their area.Some are even available online.

Never stand in a doorway during an earthquake. The safestcourse is to drop (beneath a desk or table), cover, and hold.The table surface will help protect you from falling debris.Some states mandate drills for their students, but not alladults know these simple steps. Photo: USGS


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Business lessons learned

Businesses with comprehensive contingency plans aremuch more likely to remain open after the earthquake,or reopen quickly. Experience has shown that many

businesses that close after a natural disaster neverreopen. Besides making provisions for their staffs,there are operational issues to consider.

A survey after Nisqually showed what business lead-ers learned from that earthquake.

Seismic restraints paid off: Inexpensive earthquakestraps and quake mats saved equipment and down-time. Seismic retrofits were proven in several com-panies.

Suspended ceiling grids and light fixtures need to be seis-mically restrained:If they drop, people and sprinklersystems are endangered.

Shelving must be braced: Freestanding shelvingshould be secured to the wall and/or floor. Tallshelving, like in warehouses and warehouse clubs,

should be secured to the floor, and from the top,and/or be diagonally braced.

Dont get red-tagged needlessly: Even without sig-nificant structural damage, buildings can be red-tagged because of nonstructural hazards that can

be mitigated before an earthquake.

Simple disaster plans are the best:A hospital supervi-sor said, Our disaster script needs to be rewrittenwith the highlights on ONE page at the beginningof the plan.

Train employees:People who immediately droppedunder desks or tables (drop, cover, and hold)emerged uninjured and ready to help after theshaking stopped.

Emergency drills are important:When a disaster hits,knowing where to go and what to do must be auto-matic. Fright and panic are reduced when employ-ees know what to expect.

The telephone system was overwhelmed: For the first 90minutes (to accommodate emergency calls), dontuse the phone unless you have an emergency. Af-ter the shaking stops, hang up any phones that mayhave shaken off the hook.

Employees need to contact their families: People needto let their families know they are safe, though they

should wait 90 minutes before calling. Encouragethem to arrange an out-of-state contact for familymembers to call to coordinate messages. Employ-ees will not be able to concentrate on work untilthey know their loved ones are safe.

A more general list of needs was put together by agroup of Puget Sound business representatives invited

by CREW to discuss potential post-earthquake con-

Successful response:The Boeing Company in Seattle

Within minutes after the Nisqually earth-quake, Boeing activated eight EmergencyOperations Centers and these centers werefully operational and staffed in 45 minutes.Emergency generators kicked in and within42 seconds, the companys ComputingEmergency Response Center transferredcomputing control to a backup center inWichita, Kansas.

Though the facility was evacuated, somepeople stayed behind to ensure that thegas was shut off within minutes and waterwithin the first half hour. One overhead craneoperator remained at his post until the fin ofa large commercial aircraft was no longer ahazard, saving lives and millions of dollars inproduct.

The Nisqually earthquake caused damage tothe Boeing plant but product orders were notaffected and no product delivery was de-layed. Like Starbucks, if you were a customerand you hadnt read the press, you wouldntknow Boeing had damage.

From the CREW paper, Did the NisquallyEarthquake Cause Change Within the BusinessCommunity?

See http://www.crew.org/papers/businesslearn.htmlfor more examples.


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before 6 PM, five children died in school gymnasiums.If the earthquake had struck during school hours, therewould have been significant loss of life. Another 115people died, mostly from collapsed houses and other

buildings, or falling debris. As a result, the Field Actpassed in California, mandating earthquake-resistantdesign and construction for public schools from kin-dergartens through community colleges. No Field Act

school has ever failed in an earthquake.In 2007, the State of Oregon completed a StatewideSeismic Needs Assessment of public school buildings,acute in-patient care facilities, fire stations, policestations, sheriffs offices, and other law enforcementagency buildings. This is only the first step in a multi-part process that will eventually create a pool of statemoney that can be used to seismically retrofit eligible

buildings.

Planning for the future

The City of Cannon Beach, Oregon was the pilot com-munity for a study in post-disaster, long-term recovery

planning.

Long-term recovery planning is a blueprint for howa community can be restored after a major disaster.It incorporates both long- and short-term strategies,including land use planning, business continuityplanning, and other programs. Recovery planning isa shared responsibility between individuals, private

businesses and industries, state and local governments,and the federal government.

The planning forum resulted in a number of recom-mendations for action. Here are just a few:

Establish a Disaster Resilience Committee.Develop a Post-Disaster Recovery Ordinance.

Develop a funding matrix that provides a list of po-tential funding mechanisms for disaster recoveryand mitigation activities.

Conduct a study to determine priorities for post-disaster utility restoration.

Develop a proposal to relocate or retrofit importantbuildings that are critical to post-disaster recoveryefforts.

Assist businesses in developing business continu-ity plans.

Create a list of qualified local and regional contrac-tors to perform recovery work post-disaster.

Prepare a City Continuity of Operations Plan.

Create a post-disaster housing plan that includes avacant home database.

For more information on how your community candevelop a similar plan, go to www.crew.org, and clickon Post-Disaster Recovery Planning Forum.

The mall in Scotia, California was destroyed by a re afteran earthquake. Before the re, the mall consisted of a lum-ber yard, pharmacy, coffee shop, grocery store, and vari-ety store. Long-term recovery planning gives communitiesa framework for post-disaster rebuilding. Photo: LindieBrewer, USGS

The 1971 San Fernando earthquake substantially damagedthese Juvenile Hall facilities. A portion of the two-story ad-ministration building collapsed completely into the rst sto-ry. Photo: E.V. Leyendecker, USGS


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This 24-page report givesbackground information onearthquakes in Cascadia andpresents a scenario of what amagnitude 9 earthquake mightdo to the region.

This 16-page report explainshow other groups have used

CREW scenarios and howyou can use the lessons they

learned to help your earth-quake preparations.

This 32-page guide providesan approach for assisting com-munities in identifying issuesthey will face after a disaster

This 12-page paper uses theSeattle area as a case studyof how crucial it is to under-stand inventory and supply

chain practices as part ofearthquake preparation

This 27-minute video docu-ments what risk reductionmeasures worked to

mitigate damage in the2001 Nisqually earthquake.

CREW (the Cascadia Region Earthquake Workgroup) is a partnership of the private and public sectors, created to helpour area prepare for earthquakes. A variety of products about the regions earthquake threat and how to prepare for itare available as .pdf files on our website (http://crew.org).

CREW

CREW Board of Directors

President Robert Zimmerman The Boeing CompanyVice President Andre Le Duc University of OregonSecretary Steve Charvat University of WashingtonTreasurer Timothy Walsh Washington Department of Natural ResourcesExecutive Director Bob Freitag CREWStacy Bartoletti Degenkolb EngineersMaiclaire Bolton British Columbia Provincial Emergency ProgramGeorge Crawford Washington Emergency ManagementGail Dreckman Bonneville Power AdministrationJim Goltz California Ofce of Emergency Services

Chris Jonientz-Trisler Department of Homeland SecurityMatthew A. Mabey Oregon Department of TransportationCharles Macaulay Global Risk ConsultantsVaughn Mason Work Safe Technologies

Ines Pearce Pearce Global PartnersWoody Savage United States Geological SurveyFredrick Savaglio Virginia Mason Medical CenterJoan Scoeld Washington Ofce of the Insurance Commissioner

Tracy Skinner Washington Survey and Rating BureauDave Spicer US Army Corps of EngineersWilliam Steele University of WashingtonAnn Steeves Samaritan Health Services

Yumei Wang Oregon Department of Geology and Mineral IndustriesCraig Weaver United States Geological SurveyJames Whyte British Columbia Provincial Emergency ProgramJay Wilson Oregon Emergency Management

cascadia deep earthquakes

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