oregon’s earthquake risk and resiliency (oregon department of geology and mineral industries)

8/7/2019 Oregons earthquake risk and resiliency (Oregon Department of Geology and Mineral Industries)

1/12CASCADIA Winter 2010 1

www.OregonGeology.org Oregon Department of Geology and Mineral Industries

Why does the Pacific Northwest have earthquakes?In the Pacic Northwest, two of the earths tectonic plates collide,and the boundary between them is a 600-mile-long fault called the

Cascadia Subduction Zone (CSZ). Here the Juan de Fuca Plate andthe North American plate converge at the rate of 1-2 inches per

year (3-4 cm/yr), causing stress to accumulate on the fault (calleda megathrust) that extends from Northern California to VancouverIsland. Earthquakes are caused by the abrupt release of this slowly

accumulated stress.

The eects of a great (magnitude 9.0) CSZ earthquake will reach

far inland. Shaking will be strongest on the coast but also strongin Willamette valley. We can expect up to 5 minutes of shaking

Prolonged shaking can cause structure collapse, landslides, anddisruption of lifeline services. If a CSZ earthquake generates a sig-nicant tsunami, Oregon can expect an estimated 5,000 fatalities

and over $30 billion in damages.

Oregons earthquake risk and resiliencyCreating a culture of preparedness

IN THIS ISSUE

Notes from your State Geologist page 2

Coming to terms with seismicity page 3

Preparing for earthquakes page 4

Seismic safety legislative time line page 5

Post-earthquake lifeline damage page 6

DOGAMI geohazards research page 7

TsunamiReady, TsunamiPrepared page 8

Tsunami hazard zones and maps page 9

IntraplateExample: the 2001 Nisqually, Washington

earthquake that afected Washington and

northwestern Oregon.

VolcanicExample: the 1980 Mount St. Helen

eruption-related earthquakes.

CrustalExample: the 1993 Scotts Mills and

Klamath Falls earthquakes Crusta

earthquakes also occur in southeast

ern Oregon where the crust is pulling

apart.

Cascadia Subduction ZoneExample: the 1700 earthquake that caused

shaking and a tsunami that inundated the

Oregon coast and reached as ar as Japan.

ALSO

Earthquake Educational Resources

DOGAMI Publications

Places to See

Do you know Oregonsfourkinds ofearthquake sources?

News & information from the Oregon Department of Geology and Mineral Industries WINTER 201

See page 3 for explanation of

Cascadia seismic source.

Ocean

Pacifi

c

Visit us atwww.OregonGeology.org

CASCADIA

With the Cascadia Subduction Zone oshore, Basin and Range faults to the east, and a line of volcanoes in between,

Oregon is at risk for earthquakes. Are the states infrastructure, your community, and your family ready?
http://www.oregongeology.org/http://www.oregongeology.org/http://www.oregongeology.org/http://www.oregongeology.org/http://www.oregongeology.org/


2/122 CASCADIA Winter 2010

Oregon Department of Geology and Mineral Industries www.OregonGeology.org

Notes rom your StateGeologist Oregons take away question: time or money?

Earthquake and seismological science justkeeps getting better and better. In-depth geo-logic and geophysical study of seismic zonescombined with near real-time GPS strainmeasurements of movement along faults can

provide data to pinpoint precisely where thenext earthquake along a fault zone may occurand even give us a probable notion of whenit might occur. No predictions here, folks; wecan only discuss likely activity over years anddecades, not the hours, minutes, and seconds

that are preferable for human planning andresponse.

Advances in structural engineering forearthquake and tsunami active areas meanour buildings can be designed to be saferand to be more likely to withstand a geo-logic process. Contributions from scientists inthese areas and others can provide informa-tion and tools for communities to survive anearthquake and tsunami with relatively mini-

mal loss of life and infrastructure IF commu-nities can or do respond to the information.In almost every case, time is of the essence.We in the hazard characterization and mitiga-tion business always feel we are struggling tocatch up to Mother Nature.

The recent Haiti and Chile earthquakes areprime examples. Haiti, with virtually no build-

ing codes and only a very recent understand-ing of their relative earthquake risk, sueredtremendous loss of life (>200,000) and infra-structure from an earthquake of magnitude7.0. Chile, on the other hand, has just weath-ered the fth largest earthquake recorded(magnitude 8.8, nearly 500 times strongerthan the Haiti earthquake) with a loss of about

500 lives and many buildings still standing.

What was the dierence? Awareness of themagnitude of the risk and willingness to ad-dress social issues like enforcing strict build-ing codes and outreach and education of thegeneral public.

Although at the end of the day everyonemust take some personal responsibility to be

informed, be aware, and be prepared, it is ourmission at DOGAMI to provide everyone withas much information about earthquake andtsunami hazards as possible and to providemitigation tools to reduce the risk a risk wenow know is nearly as high as Chiles.

We have accelerated our tsunami mitiga-tion program by setting forth the goal to havenew, expanded inundation maps for the entireOregon coast by 2013. These will be followedby new evacuation maps designed with inputfrom the Tsunami Advisory Group, whosemembers represent the end users for ourproducts. Our earthquake and tsunami hazards

outreach and education projects are now anequal part of our hazard mitigation program.We are focusing on grass roots projects such

as placing tsunami preparedness coordinatorsin coastal communities to conduct educationand outreach. It will still take several years forus to complete the maps and to develop fullythe outreach.

With earthquake science and engineer-ing it is a similar story. Over the past decadeDOGAMI has worked with dozens of stateagencies, emergency responder communi-ties, two Governors oces, and scores of leg-islators to implement the Oregon EmergencyManagement Seismic Rehabilitation Grant Pro-gram. This grant program awards state bond

funds to public school districts and emergencyresponse facilities that are in need of seismicretrot and that have successfully applied forfunds.

After seeing the destruction of the 2004Sumatra earthquake and tsunami we recog-nize that infrastructure (water mains, bridges,railroad lines, fuel storage, transmission lines,

etc.) is very vulnerable, is costly to repair andreplace, and frequently is the reason that anarea remains uninhabitable long after thehazard has abated. How do we assess the infra-structure vulnerability in Oregon and prioritizeretrots? Will it take us another 10 years to de-

velop a plan to begin the x?I end this message with a note from Paul

Mann, senior research scientist with the In-stitute for Geophysics at University of Texasat Austin. In an American Geophysical UnionEos magazine interview (January 26, 2010) hecautioned, Countries with faults threateningdense populations need to approach earth-quake defense with the same energy, consis-tency, and level of scientic spending as devot-

ed to their military defense. I completely agree;we should be defending against hazards now,not after the fact.

by Vicki S. McConnell, Oregon State Geologist

Cascadia is published by the OregonDepartment of Geologyand Mineral Industries

800 NE Oregon Street, #28,Suite 965, Portland, OR 97232

(971) 673-1555 fax (971) 673-1562

Governing BoardLarry Givens, Chair, Milton-Freewater

Stephen H. Macnab, Vice Chair, BendR. Charles Vars, CorvallisLisa Phipps, Tillamook

Douglas W. MacDougal, Portland

State Geologist Vicki S. McConnellAssistant Director Don Lewis

Cascadia special contributor Yumei WangCascadia design Deb Schueller

Mineral Land Regulation

and Reclamation Program

229 Broadalbin Street, SW, Albany, OR 97321(541) 967-2039 fax (541) 967-2075

Gary W. Lynch, Assistant Director

Baker City Field OfficeBaker County Courthouse1995 3rd Street, Suite 130

Baker City, OR 97814(541) 523-3133 fax (541) 523-5992Mark L. Ferns, Regional Geologist

Coastal Field Office313 SW 2nd Street, Suite D

Newport, OR 97365(541) 574-6642 fax (541) 265-5241

Jonathan C. Allan, Coastal Team Leader

The Nature of the Northwest

Information Center800 NE Oregon Street, #28, Suite 965

Portland, OR 97232-2162(971) 673-2331 fax (971) 673-1562

Donald J. Haines, ManagerInternet: http://www.NatureNW.org

For free copies of this and pastissues ofCascadia, visit

www.OregonGeology.org

ORE

G

O

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DEPARTMEN

T OFGEOLOGYAN

DMIN

ER

AL

I

N

D

USTR

IES

1937
http://www.oregongeology.org/http://www.agu.org/pubs/pdf/2010EO040002.pdfhttp://www.naturenw.org/http://www.oregongeology.org/http://www.oregongeology.org/http://www.naturenw.org/http://www.agu.org/pubs/pdf/2010EO040002.pdfhttp://www.oregongeology.org/


3/12

CASCADIA Winter 2010 3


NORTH AMERICAN PLATEAccretionaryPrism

Trench

LockedTransition

Slip

Cascadia seismic source

Oregons earthquake hazards come not only from different kinds of earthquakesand from associated tsunamis but from damage that can result from processestriggered by these events. Understanding earthquakes and how damage occurscan help you prepare your home or busi ness. (See pages 4-5 for how to prepare.)

fault A break in the earths crust which ruptures during an earth-quake, allowing the two sides of the fault to slip past each other.

The slippage may range from less than an inch to more than 30

feet in a severe earthquake.

earthquake Seismic vibrations produced when a fault in the earths

crust ruptures or breaks, causing movement or slippage of the

rocks along the fault.

seismic waves Vibrations that travel outward from the earthquake

fault at speeds of several miles per second. Although fault slip-

page directly under a structure can cause considerable damage,

seismic waves cause most of the destruction during earthquakes.

magnitude The amount of energy released during an earthquake.

An increase of one full point on a magnitude scale represents

about a 30-fold increase in the energy released. Therefore, an

earthquake measuring magnitude 6.0 is about 30 times morepowerful than one measuring 5.0.

intensity The severity of an earthquake in terms of its effects on the

earths surface and on humans and their structures. The intensity

for a particular earthquake will vary depending on the distance

from the epicenter and the type of soil and rock at the site.

epicenter The place on the earths surface directly above the point on

the fault where the earthquake rupture begins. Once the rupture

begins, it expands along the fault during the earthquake and can

extend hundreds of miles before stopping.

foreshock An earthquake that precedes the main earthquake.

main shock The largest magnitude earthquake in a group of earth-

quakes.

aftershock An earthquake of similar or lesser intensity that followsthe main earthquake.

Cascadia seismic source, locked zone, transition zone, and rupture zone

The Cascadia subduction zone is locked where the rock is not

slipping because frictional resistance on the fault is greater

than the stress across the fault. The transition zone separates

the locked zone from the zone of continuous sliding to the east.

Stored energy is eventually released in an earthquake when fric-

tional resistance is overcome. The rupture zone is the area along

which the earthquake can occur; it is equivalent to the pink

zones shown in the diagram.

coseismic subsidence Relative rises and falls

in land, sea floor, and sea level

caused by the buildup and

release of stress associated

with great (magnitude 9)underwater earthquakes.

liquefaction A process by which water-saturated sediment temporar

ily loses strength and acts as a fluid when exposed to strong seis

mic shaking. The shaking causes the grains to lose grain-to-grain

contact, so the sediment tends to flow. Liquefaction is most likely

in loose sandy soil with a shallow water table.

earthquake liquefaction hazards

If an earthquake induces

liquefaction, several things

can happen: The liquefied

layer and everything lyingon top of it may move

downslope. Alternatively,

the layer may vibrate

with displacements large

enough to rupture pipelines,

move bridge abutments, or

rupture building founda-

tions. Light objects, such

as underground storage

tanks, can float toward the

surface, and heavy objects,

such as buildings, can sink.

Thus, if the soil at a siteliquefies, the damage result-

ing from an earthquake can be

dramatically increased over what

shaking alone might have caused.

earthquake ground-shaking amplification hazards Soils and soft sedimen

tary rocks near the surface can modify bedrock ground shaking

caused by an earthquake. This modification can increase (o

decrease) the strength of shaking or change the frequency of the

shaking. The nature of the modifications is determined by the

thickness of the geologic materials and their physical properties

such as stiffness.

earthquake-induced landslide hazards Steep and moderate slopes can

produce landslides during earthquakes. Not all landslides occu

in the first few minutes following an earthquake; some can occu

days later. In 1949, a large landslide near Tacoma, Washington

slipped three days after the earthquake. The steep slopes along

the edges of the Willamette Valley, often near saturated condi

tions because of high rainfall, are candidates for earthquake

induced failure. Road cuts and fills can also have slope failures.

lateral spreading A kind of landslide that forms on gentle slopes and

that has rapid fluid-like flow movement, often associated with

liquefaction.

Coming to terms with seismicity

See animations of earthquake terms and concepts:http://earthquake.usgs.gov/learn/animations/

Cross section

of the Cascadia Subduction

Zone and the interface between the Juan

de Fuca and North American plates. The locked

zone (dark pink surface) and transition zone (light pink sur-

face) can be the source of next great earthquake. The gray surface is

the deeper slip zone. (image modified from Geological Survey of Canada

[http://gsc.nrcan.gc.ca/geodyn/casaction_e.php])

SUBDUCTINGPLATELo

ckedzone

Shortening

Uplift

Coastline(image modified from Geological

Survey of Canada)

Before anearthquake

Loosely packed grains;pore spaces lled

with water. Water-saturatedgranular layer

Sediment layer

During anearthquake

Tightly packed grains

Grains pushed apartby upward ow

Sand injectedoverlying sediSand boils

Sand dike

LIQUEFACTION
http://www.oregongeology.org/http://gsc.nrcan.gc.ca/geodyn/casaction_e.phphttp://gsc.nrcan.gc.ca/geodyn/casaction_e.phphttp://www.oregongeology.org/




6. Help Your Community Get Ready

Publishaspecialsectioninyourlocalnewspaperwithemer-gency informationon earthquakes.Localize the informationbyprintingthephonenumbersoflocalemergencyservicesof

fices,theAmericanRedCross,andhospitals.Conductaweek-longseriesonlocatinghazardsinthehome.WorkwithlocalemergencyservicesandAmericanRedCrosofficialstopreparespecialreportsforpeoplewithmobilityimpairmentsonwhattododuringanearthquake.

Providetipsonconductingearthquakedrillsinthehome.Interviewrepresentativesofthegas,electric,andwatercompaniesaboutshuttingoffutilities.

Worktogetherinyourcommunitytoapplyyourknowledgetobuildingcodes,retrofittingprograms,hazardhunts,andneighborhoodandfamilyemergencyplans.

What to do BEFORE an earthquake

What to do DURING an earthquake

Earthquakes strike suddenly, violently and without warning. Identifying

potential hazards ahead of time and advance planning can reduce the

dangers of serious injury or loss of life from an earthquake. Here are six

ways to plan ahead.

1. Check for Hazards in the HomeFastenshelvessecurelytowalls.Placelargeorheavyobjectsonlowershelves.Storebreakableitemssuchasbottledfoods,glass,andchinainlow,closedcabinetswithlatches.

Hangheavyitemssuchaspicturesandmirrorsawayfrombeds,couches,andanywherepeoplesit.

Braceoverheadlightfixtures.Repairdefectiveelectricalwiringandleakygasconnections.Secureawaterheaterbystrappingittothewallstudsandbolt-ingittothefloor.

Repairanydeepcracksinceilingsorfoundations.Getexpertadviceiftherearesignsofstructuraldefects.

Storeweedkillers,pesticides,andflammableproductssecurelyinclosedcabinetswithlatchesandonbottomshelves.

2. Identify Safe Places Indoors and Outdoors

Understurdyfurnituresuchasaheavydeskortable.Againstaninsidewall.Awayfromwhereglasscouldshatteraroundwindows,mirrors,pictures,orwhere heavybookcases orother heavyfurniturecouldfallover.

Intheopen,awayfrombuildings,trees,telephoneandelectri-callines,overpasses,orelevatedexpressways.

3. Educate Yourself and Family Members

ContactyourlocalemergencymanagementofficeorAmerican

RedCrosschapterformoreinformationonearthquakes.Teachchildrenhowandwhentocall9-1-1,police,orfirede-partmentandwhichradiostationtotunetoforemergencyin-formation.

Teachallfamilymembershowandwhentoturnoffgas,elec-tricity,andwater.

4. Have Disaster Supplies on Hand

Flashlightandextrabatteries.Portablebattery-operatedradioandextrabatteries.Firstaidkitandmanual.Emergencyfoodandwater.Nonelectriccanopener.Essentialmedicines.

Cashandcreditcards.Sturdyshoes.

5. Develop an Emergency Communication Plan

Incasefamilymembersareseparatedfromoneanotherduringanearthquake(arealpossibilityduringthedaywhenadultsareatworkandchildrenareatschool),developaplanforreunitingafterthedisaster.

Askan out-of-staterelative orfriend toserveas the familycontact.Afteradisaster,itsofteneasiertocalllongdistance.Makesureeveryoneinthefamilyknowsthename,address,andphonenumberofthecontactperson.

Stay as safe as possible during an earthquake. Be aware that some earth

quakes are actually foreshocks and a larger earthquake might occur

Minimize your movements to a few steps to a nearby safe place and stay

indoors until the shaking has stopped and you are sure exiting is safe.

Indoors

DROPtotheground;takeCOVERbygettingunderasturdtableorotherpieceoffurniture;andHOLDONonuntiltheshakingstops.Ifthereisntatableordesknearyou,coveryoufaceandheadwithyourarmsandcrouchinaninsidecorneofthebuilding.

Stayawayfromglass,windows,outsidedoorsandwalls,and

anythingthatcouldfall,suchaslightingfixturesorfurniture.Stayinbedifyouaretherewhentheearthquakestrikes.Holdonandprotectyourheadwithapillow,unlessyouareundeaheavylightfixturethatcouldfall.Inthatcase,movetothenearestsafeplace.

Useadoorwayforshelteronlyifitisinclosebyandyouknowitisastronglysupported,load-bearingdoorway.

Stayinsideuntilshakingstopsanditissafetogooutside.Researchhasshownthatmostinjuriesoccurwhenpeopleinsidebuildings attempt tomove to a differentlocation inside thbuildingortrytoleave.

Beawarethattheelectricitymaygooutorthesprinklersys-temsorfirealarmsmayturnon.

DONOTusetheelevators.Outdoors

Staythere.Moveawayfrombuildings,streetlights,andutilitywires.Onceintheopen,staythereuntiltheshakingstops.Thegreatestdangerexistsdirectlyoutsidebuildings,atexits,andalong-sideexteriorwalls.Groundmovementduringanearthquakeiseldomthedirectcauseofdeathorinjury.Mostearthquakerelatedcasualtiesresultfromcollapsingwalls,flyingglass,andfallingobjects.

(from FEMA: http://www.fema.gov/hazard/earthquake/)

Pack

everything

in backpacks

so you are

ready to go.
http://www.oregongeology.org/http://www.fema.gov/hazard/earthquake/http://www.fema.gov/hazard/earthquake/http://www.oregongeology.org/


5/12



1990 2000 2010 2020 2030 204

Oregons seismic safety legislative time line

1991

As a result of

citizen con-

cern after the

1989 Loma

Prieta, Calif.,

earthquake,

Oregon Senate

Bill 96 created

the Oregon

Seismic SafetyPolicy Advisory

Commission

(OSSPAC)

to increase

Oregons

awareness to

earthquake

hazards by

supporting

earthquake

education,

research,

mitigation, and

legislation.

1994

Oregons first

statewide

seismic

building

code (Oregon

Structural

Specialty

Code)

adopted.

New buildingdesigns must

incorporate

seismic

provisions.

Many build-

ings built

before 1994

will not be

able to with-

stand shaking

from earth-

quakes and

are at risk of

collapse.

2001

Statute 455.400required seismiclife-safety inschools andemergency facili-ties. Five pieces oflegislation intro-duced at requestof Senator Peter

Courtney aspart of OSSPAC:Senate Bills 13,14, 15 and SenateJoint Resolutions(SJRs) 21 and 22.All passed. Drillsrequired of largeemployers (pri-vate and public).SJRs created bal-lot measures. Law(ORS 455.400)required schoolsand emergencyfacilities to be

seismically safe.

2002

Ballot Measures21 and 22passed, allow-ing for ~$1.2billion of statebonds for seis-mic upgrades.

These seismicupgrades are for

public schoolsand emergencyfacilities. (Referto ConstitutionalArticles XI-M andXI-N.)

2005

Senate Bills2, 3, 4, and 5,introducedby SenatePresidentPeter Court-ney, requiredstatewideseismic needs

assessment, agrant program,and authorizedstate bonds.First time publicuniversitiesreceived seismicmitigationfunds.SB 2 directedDOGAMI to con-duct statewiderisk study. SB 3directed OregonEmergencyManagement

(OEM) to startgrant program.SB 4 and 5 al-lowed Dept. ofAdministrativeServices (DAS)and Treasury toissue XI-M andXI-N bonds.

2007DOGAMI pub-lished seismicreport (Open-FileReport O-07-02)indicating 3,352educational andemergency facili-ties buildings areat seismic risk.

SB 1 pro-vided OregonEmergencyManagement(OEM) funds forfour new staff toestablish grantprogram.

(In 2008the OregonDepartmentof Educationcreated the

The QuakeSafe Schools

program to shareinformationon the seismicscores and otherearthquakepreparednessinformation withthe public.)

2009

SeismicRehabilitationGrant Programprovided $30million in statebond funds($15 million forpublic schoolsand $15 million

for fire, police,and hospitals[$1.2 billionauthorizedby voters]) tobegin seismicmitigation ofschools andemergencyfacilities andto improvecommunitypreparedness.

(In 2011 morestate bond

funding is slatedto be appropri-ated for addi-tional seismicupgrades.)

2022

Seismicmitigationto becompletedforemergencyfacilities (fireand policestations,

acute carehospitals,andemergencyoperationcenters).

2032

Seismicmitigationto becompletedfor publichigh-occupancyschools(K12,

communitycollegesanduniversities).

Scotts Mills, Oreg., earthquake, M 5.6, 1993Klamath Falls, Oreg., earthquakes, M 6.0, 1993

21st centuryhighly destructive

earthquakes

2001 Gujarat M 7.7 > 20,000 killed2003 Bam, Iran M 6.5 > 40,000 killed2004 Sumatra M 9.1 ~ 230,000 killed2005 Kashmir M 7.6 > 79,000 killed2008 Chengdu M 8.0 ~ 90,000 killed

2010 Haiti M 7.0 > 200,000 killed2010 Chile M 8.8 > 500 killed

Loma Prieta, Calif., earthquake, M 6.9, 1989

Resources:

Oregon Emergency Management Seismic Rehabilitation Grant Program: http://www.oregon.gov/OMD/OEM/

Oregon Department of Education Quake Safe Schools: http://www.ode.state.or.us/go/quakesafeschools/

DOGAMI seismic needs assessment study (O-07-02): http://www.oregongeology.org/sub/projects/rvs/default.htmOregon Seismic Safety Policy Advisory Commission (OSSPAC): http://www.oregon.gov/OMD/OEM/osspac/osspac.shtml

2007 Oregon Structural Specialty Code: http://www2.iccsafe.org/states/oregon/07_Structural/Building07_Frameset.htm

Collapse potential for all educational

and emergency sites in DOGAMIs seis-

mic needs assessment study (O-07-02).

These sites occur throughout Oregon.

Over 1,300 buildings have high to very

high seismic collapse potential.

Eureka, Calif., earthquake, M 6.5, 2010Nisqually, Wash., earthquake, M 6.8, 2001Northridge, Calif.,

earthquake, M 6.7,1994

Relative Collapse Potential Very High (100%) High (>10%) Moderate (>1%) Low (




Certain infrastructure systemsfor example, fuel, electrical, water,

highwayare called lifelines because our lives depend on them.While the seismic provisions in Oregons current building code

(Oregon Structural Specialty Code) mean new buildings will beable to withstand most earthquakes, our roads, bridges, and elec-

trical and waterlines might not fare as well. Disruption to thesecritical services could dramatically slow aid and relief eortsashappened after the February 2010 Chile earthquake.

Lifelines often depend on each other, so that failure of one canaect other systems. For example, the telecommunications system

requires cooling, which requires electricity, gas or liquid fuel, andwater. If a water pipeline is located on a bridge and the bridge col-

lapses in an earthquake, then the bridge, the water services, and

the telecommunication lines will all be down.

Oregons lifelines were constructed to standards well below current seismic safety specications. In a major earthquake, many o

our critical lifelines, such as major highways, fuel ports, electricatransmission, and telecommunication systems will not be able to

provide their intended services.Understanding lifeline locations, their interdependencies, and

their locations in relationship to earthquake hazards is only the rs

step toward making lifeline systems seismically resilient. After riskidentication and assessment, stakeholders can be identied and

engaged, and risk prioritized and mitigated. Oregon is currently fo-cusing on reliable fuel supply, electricity, and gas service as part o

a state energy assurance project.

Post-earthquake lifeline damage

Close-up of Portland metro area from Earthquake Hazards and Lifelines in the Interstate 5 Urban Corridor

Woodburn to Centralia, Washington, by E. A. Barnett and others (U.S. Geological Survey Scientific InvestigationsMap 3027 [http://pubs.usgs.gov/sim/3027/]). The I-5 corridor from Cottage Grove to Woodburn, Oregon, has also

been studied (U.S. Geological Survey Scientific Investigations Map 3028 [http://pubs.usgs.gov/sim/3028/]).

The majority of Oregon state-ownedbridges built between 1950 and 1980

are seismically vulnerable. An Ore-gon Department of Transportation 2009

study (http://library.state.or.us/reposito-ry/2009/200911171034432/) found thatOregon would face devastating damage

to the transportation system from a largeCascadia Subduction Zone earthquake

or a crustal earthquake located in the Wil-lamette Valley. Coastal U.S. Highway 101

would have dozens of impassable loca-tions due to bridge failures, and all high-ways connecting U.S. 101 and I-5 would

be impassable due to bridge damage.Vulnerable bridges will need strengthen-

ing or replacement to ensure that theysurvive a large earthquake.

PORTLAND

Beaverton

Gresham

Milwaukie

Tigard

Fairview

Troutdale

Camas

VANCOUVER

1962, Mag 5.2

217

405

208

99E 30

213

205

5

30

: . . l i l i l l i- i i l l i l

i .

. - . - . - . -

. . . .

Major water supply line, water treatmentplantMajor sewer pipeline, treatment plant

Natural gas pipelineLiquid fuel pipeline

Interstate highwayState highways, and other major roads

Railroad

Major airport

Minor airport

Electric transmission line, 115kV, 230kV, 500kV

(map lines with thicker width are adjacent pipelines)

Lifeline Systems

Aerial view of collapsed

sections of the Cypress via-

duct of Interstate Highway

880, Oakland, California,

after the 1989 Loma Prietaearthquake (H. G. Wilshire,

U.S. Geological Survey).
http://www.oregongeology.org/http://pubs.usgs.gov/sim/3027/http://pubs.usgs.gov/sim/3028/http://library.state.or.us/repository/2009/200911171034432/http://library.state.or.us/repository/2009/200911171034432/http://pubs.usgs.gov/sim/3027/http://library.state.or.us/repository/2009/200911171034432/http://library.state.or.us/repository/2009/200911171034432/http://pubs.usgs.gov/sim/3028/http://pubs.usgs.gov/sim/3027/http://www.oregongeology.org/


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Coos County multi-hazard mappingDOGAMI is conducting Digital Flood Insurance Rate Map

(DFIRM) ood-plain redelineation for the Federal Emergency Man-

agement Agency (FEMA) using lidar-based data to create the basemaps. Once the base maps are created, DOGAMI will use the new

base imagery to identify and map channel migration zone hazards;100-year and 500-year ood hazard loss estimation (using HAZUS,

FEMAs risk assessment methodology); landslide hazards; earth-quake hazards including liquefaction and ground shaking ampli-cation; tsunami inundation hazards; and coastal erosion hazards.

The multi-hazards maps will be available in paper format and indigital format via an interactive web map.

Portland urban area geologic hazard assessmentDOGAMI is partnering with the U.S. Geologic Survey (USGS) to

make a new, state-of-the-art digital geologic map and databaseof the greater Portland urban area, stretching from Estacada to St.

Helens, Washougal to Newberg. The map will feature highly de-tailed geology mapped on new lidar imagery, which allows geolo-

gists to see unprecedented detail in the shape of surface. The datafrom the new map will be used to make detailed landslide and

earthquake hazard maps of the area in cooperation with local gov-ernments and the USGS.

Multi-hazard risk and vulnerability assessments for Mount Hood The goal of this USGS-funded, 1-year project is to assist

communities within the Mount Hood, the Highway 26/SandyRiver corridor, and the Highway 35/Hood River corridor study area

in understanding the risk associated with volcanic, earthquake,landslide, and ooding hazards. DOGAMI is compiling existing

hazard and asset data throughout the study as well as creatingnew data using lidar-based maps.

Pre-Disaster Mitigation (PDM) studies for mid/southernWillamette Valley, mid Columbia River Gorge,and south central Oregon

The purpose of these studies is to help communities prepare

pre-disaster mitigation plans, identify potential geologic hazards,help communities perform earthquake damage and loss estima-tion, and to recommend future action items. Products include digi-

tal GIS layers for each community, depicting relative earthquake

ground shaking amplication hazards, relative earthquake lique-faction hazards, relative earthquake-induced landslide hazards,and identied landslide areas. Damage and loss estimates for each

community were analyzed for two earthquake scenarios. The mid/southern Willamette study is complete (DOGAMI IMS-24); the othertwo studies will be published in 2010. Funding was provided by

FEMA with matching funds from the State of Oregon.

DOGAMI geohazards research

Advanced National Seismic System, Pacific Northwest Region

The Advanced National Seismic System (ANSS) is a U.S. Geo-logical Survey eort to coordi-

nate and upgrade seismic-mon-itoring networks nationwide

and to implement rapid dis-tribution of earthquake infor-mation. Under the ANSS, the

Pacic Northwest Seismic Net-work (PNSN) has begun install-

ing a new generation of digitalearthquake sensors in urban

areas that can accurately recordground motions. This infor-

mation will help improve the design of future buildings to

be earthquake resilient. Information on the intensity anddistribution of ground shaking can be used by emergen-

cy managers to direct rescue service to hard-shaken areas. This information is available on USGS and PNSN web sites.

http://pubs.usgs.gov/fs/2004/3073/pdf/Factsheet3073.pdf

Tsunami hazard modeling and Cascadia paleoseismicityDOGAMI coastal geologists continue revising tsunami inun

dation maps that cover the states entire 362-mile-long coastlineusing sophisticated computer models coupled with laser-basedterrain mapping and eld-based geologic investigations. Product

include tsunami inundation and evacuation maps and grass-rootsoutreach and education to coastal communities.

DOGAMI geologist Rob Witter (left) and USGS geologist Brian Atwater (right) pres

ent evidence for great Cascadia earthquakes and tsunamis to middle school science

teachers participating in the Teachers on the Leading Edge program, supported by the

National Science Foundation. Bob Butler, University of Portland earth science educator

is at far right. (Photo: James Roddey, DOGAMI)
http://www.oregongeology.org/http://pubs.usgs.gov/fs/2004/3073/pdf/Factsheet3073.pdfhttp://pubs.usgs.gov/fs/2004/3073/pdf/Factsheet3073.pdfhttp://www.oregongeology.org/




(epicenter of earthquake)

north coast, Yachats, Waldport, and Seal Rock onthe central coast, and Bandon on the south

coast. State parks adjacent to these communities will also participate.

TsunamiReady, TsunamiPrepared is administered by DOGAMI in collaboration with

Oregon Emergency Management, the Oregon Coastal Zone Management Associationand the National Weather Service. For more

information contact James Roddey, OregonDepartment of Geology and Mineral Indus

tries, (971) 673-1543.

TsunamiReady, TsunamiPrepared will also

accelerate the remapping of the Oregoncoast for tsunami inundation using state of

the art computer modeling and laser basedterrain mapping (lidar). The outcome will be

the creation of new, more accurate tsuna-mi evacuation maps for the entire 362-milelength of the Oregon coast.

Communities chosen for the rst year ofaccelerated funding of the TsunamiReady,

TsunamiPrepared program include RockawayBeach, Manzanita, Nehalem, and Wheeler on the

Scientic research looking 10,000 years intothe geologic past indicates great earth-quakes and tsunamis generated by a rup-

ture of the Cascadia Subduction Zone haveoccurred with alarming frequency (see time

line below). The last great earthquake hap-pened just over 300 years ago, and we can

expect another of these great earthquakesand tsunamis at any time. An earthquake

could result in a tsunami inundating the Or-egon coast within 15 to 30 minutes. Beforethat, ground shaking could cause liquefac-

tion, landslides, and coastal subsidence.TsunamiReady, TsunamiPrepared, a multi-

year, multi-million dollar program funded bythe National Tsunami Hazard Mitigation Pro-

gram and overseen by the U.S. Departmentof Commerces National Oceanic and Atmo-spheric Administration (NOAA), has the goal

of reaching every resident and visitor at theOregon coast with a message of how to pre-

pare for and respond to an earthquake andtsunami generated by a rupture of the Cas-

cadia Subduction Zone.The program will build on the work coast-

al communities have already accomplished

or assist in work they are ready to begin bysupporting a grass roots program of aware-

ness and preparedness. TsunamiReady, Tsu-namiPrepared will also provide much need-

ed resources to help these communitiescreate or maintain a sustained eort of edu-cation and preparation.

Oregon coastal communities will be TsunamiReady, TsunamiPrepared

low waves spread

out from epicenter

waves pile u

when they h

shallow wate

(image modified from Geoscience Australia [http://www.ga.gov.au/hazards/tsunami/]

where the image appears courtesy of the Russian Academy of Sciences)

HOW A TSUNAMI IS GENERATED

Earthquake of Magnitude 9+ (fault breaks along entire subduction zone)

Earthquake of Magnitude 8+ (fault breaks along southern half of subduction zone)

YEARS BC YEARS AD

KNOWN CASCADIA EARTHQUAKES ALONG THE CASCADIA SUBDUCTION ZONE IN NORTHERN CALIFORNIA, OREGON, AND WASHINGTON

8000 7000 6000 5000 4000 3000 2000 1000 0 1000 2000

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CASCADIA EARTHUAE TIME LINE

Comparison of the history of subduction zone earthquakes along the Cascadia Subduction Zone in northern California, Oregon, and Washington,with events from human history. Ages of earthquakes are derived from study and dating of submarine landslides triggered by the earthquakes.Earthquake data provided by Chris Goldfinger, Oregon State University; time line by Ian P. Madin, DOGAMI.

New multi-year tsunami mapping and outreach program

GENERATION

PROPAGATION

INUNDATION

FAULT
http://www.oregongeology.org/http://www.ga.gov.au/hazards/tsunami/http://www.ga.gov.au/hazards/tsunami/http://www.oregongeology.org/


9/12



Tsunami vertical refuges

On September 28-29, 2009, the CascadiaRegion Earthquake Workgroup (CREW)

held the Pacic Northwest regions rstworkshop on tsunami vertical evacua-

tion buildings (TEBs) as a way to protectpeople and to improve community recov-

ery in the event of a tsunami.TEBs, reinforced concrete buildings on

robust deep foundations that allow water

to ow through the rst oor, could be stra-tegically located in low-lying coastal com-

munities. Elevated platforms designed towithstand earthquake and tsunami forces

could be erected in state parks.Cannon Beach, Oregon, may become

the rst community in the United Statesto erect a TEB. Several designs for a newcity hall building were showcased and

discussed at the CREW workshop. Thedesigns feature wave-dissipation struc-

tures in the front and back, and refuge forabout a 1,000 people. With about 50% of

residents and 75% of businesses in thetsunami zone, the City of Cannon Beach isexploring options on how to fund a new

state-of-the art, sustainable TEB. Depend-ing on the features, a TEB structure would

add $1-2 million to the cost of a new cityhall.

The CREW workshop minutes are avail-able as DOGAMI Open-File Report O-10-02. For more information on TEBs, contact

Yumei Wang, DOGAMI Geotechnical En-gineer, at (971) 673-1551 or email yumei.

[email protected].

Tsunami evacuation maps and information available online

Conceptual illustration by Jay Raskin, president

of Ecola Architects and former mayor of Cannon

Beach, of a proposed new Cannon Beach City

Hall. The elevated building could double as a

tsunami evacuation shelter for people who do

not have time to reach higher ground as well as

ensure that city government services continue

to function during all but the largest tsunamis.

Online interactive maps and evacuation brochure maps show tsunami inundation zones for

Oregon coastal communities such as the Cannon Beach area shown above.

Oregon Coast Local Emergency Preparedness Agencies

Clatsop County Sherifs Oce, Emergency Services: http://www.co.clatsop.or.us/deault.

asp?pageid=391&deptid=5

Coos County Emergency Services: http://www.cooscountysherif.com/tsunami.htm

Curry County Emergency Services: http://www.co.curry.or.us/Emergency%20Services/emergency_Services.htm

Douglas County Emergency Services:http://www.dcso.com/tsunami_maps.asp

Lane County Emergency Management:http://www.lanecounty.org/EmerMgmt/deault.htm

Lincoln County Emergency Services: http://www.lincolncoemergencyservices.us/home.cm?dir_cat=34589

Tillamook County Emergency Management: http://www.co.tillamook.or.us/gov/EMGMGNT/

NOAA West Coast and Alaska Tsunami Warning Center: http://wcatwc.arh.noaa.gov/American Red Cross, Oregon Chapters:http://www.oregonredcross.org/index.asp?IDCapitulo=663B0ID44V

Oregon State Police: http://www.oregon.gov/OSP/

Oregon Emergency Management: http://www.oregon.gov/OMD/OEM/

Will you know where to go if a tsunami hits?A tsunami caused by an undersea earth-quake near the Oregon coast is called a lo-cal tsunami. An undersea earthquake in the

Pacic Ocean far away from the coast maycause a distant tsunami.

A distant tsunami will take 4 hours ormore to come ashore. No earthquake will

be felt at the coast, and the tsunami willgenerally be smaller than that from a local

earthquake. Typically, there is time for anocial warning and evacuation to safety.

A local tsunami can come onshore

within 15 to 20 minutes after the earth-quakebefore there is time for an ocial

warning from the national warning system.Ground shaking from the earthquake may

be the only warning you have. After the

ground stops shaking, evacuate on foot, ifpossible. Follow evacuation signs and ar-

rows.

Coastal residents andvisitors can prepare for the

possibility of a tsunami bybecoming familiar with the

tsunami hazard zones andevacuation routes in their

communities. Oregon tsunamievacuation zone maps for some commu-nities are online, and more are planned.

See your local emergency preparednessagency for specic information on tsunami

shelters and other specic evacuation in-structions for your community.

Online interactive evacuation maps:http://www.nanoos.org/data/products/oregon_tsunami_

evacuation_zones/index.php.

Evacuation brochures:http://www.oregongeology.org/sub/earthquakes/Coastal/Tsumaps.htm
http://www.oregongeology.org/mailto:yumei.wang%40dogami.state.or.us?subject=Tsunami%20Evacuation%20Buildingsmailto:yumei.wang%40dogami.state.or.us?subject=Tsunami%20Evacuation%20Buildingshttp://www.co.clatsop.or.us/default.asp?pageid=391&deptid=5http://www.co.clatsop.or.us/default.asp?pageid=391&deptid=5http://www.cooscountysheriff.com/tsunami.htmhttp://www.co.curry.or.us/Emergency%20Services/emergency_Services.htmhttp://www.dcso.com/tsunami_maps.asphttp://www.dcso.com/tsunami_maps.asphttp://www.lanecounty.org/EmerMgmt/default.htmhttp://www.lanecounty.org/EmerMgmt/default.htmhttp://www.lincolncoemergencyservices.us/home.cfm?dir_cat=34589http://www.co.tillamook.or.us/gov/EMGMGNT/http://wcatwc.arh.noaa.gov/http://www.oregonredcross.org/index.asp?IDCapitulo=663B0ID44Vhttp://www.oregonredcross.org/index.asp?IDCapitulo=663B0ID44Vhttp://www.oregon.gov/OSP/http://www.oregon.gov/OMD/OEM/http://www.nanoos.org/data/products/oregon_tsunami_evacuation_zones/index.phphttp://www.nanoos.org/data/products/oregon_tsunami_evacuation_zones/index.phphttp://www.oregongeology.org/sub/earthquakes/Coastal/Tsumaps.htmhttp://www.oregongeology.org/sub/earthquakes/Coastal/Tsumaps.htmhttp://www.nanoos.org/data/products/oregon_tsunami_evacuation_zones/index.phphttp://www.nanoos.org/data/products/oregon_tsunami_evacuation_zones/index.phphttp://www.oregon.gov/OMD/OEM/http://www.oregon.gov/OSP/http://www.oregonredcross.org/index.asp?IDCapitulo=663B0ID44Vhttp://wcatwc.arh.noaa.gov/http://www.co.tillamook.or.us/gov/EMGMGNT/http://www.lincolncoemergencyservices.us/home.cfm?dir_cat=34589http://www.lanecounty.org/EmerMgmt/default.htmhttp://www.dcso.com/tsunami_maps.asphttp://www.co.curry.or.us/Emergency%20Services/emergency_Services.htmhttp://www.cooscountysheriff.com/tsunami.htmhttp://www.co.clatsop.or.us/default.asp?pageid=391&deptid=5http://www.co.clatsop.or.us/default.asp?pageid=391&deptid=5mailto:yumei.wang%40dogami.state.or.us?subject=Tsunami%20Evacuation%20Buildingsmailto:yumei.wang%40dogami.state.or.us?subject=Tsunami%20Evacuation%20Buildingshttp://www.oregongeology.org/




DOGAMI earthquake hazard maps (IMS series)

online

http://www.oregongeology.org/sub/publications/IMS/ims.htm

Geologic hazards, earthquake and landslide haz-

ard maps, and future earthquake damage esti-

mates for six

counties in the

Mid/Southern

Willamette

Valley includ-

ing Yamhill, Marion, Polk, Benton, Linn, and Lane

Counties, and the City of Albany, Oregon (Interpre-

tive Map 24), by W. J. Burns, R. J. Hofmeister, and Y. Wang,

2008, 121 p., map scale 1:422,400.

Oregon Public Utilities Commission--Oregon

Department of Geology and Mineral Industries

Leadership Forum and Seismic Critical Energy

Infrastructures Workshop, April 2, 2008 (Open-File

Report 08-10), by Y. Wang and J. R. Gonzalez, 2008, 13 p.

Statewide seismic needs assessment:

Implementation of Oregon 2005 Senate Bill

2 relating to public safety, earthquakes, and

seismic rehabilitation of public buildings (Open-

File Report 07-02), by D. Lewis, 2007, 140 p. plus app.

http://www.oregongeology.org/sub/projects/rvs/deault.htm

Enhanced rapid visual screening (E-RVS) for

prioritization of seismic retrots in Oregon,

(Special Paper 39), by Y. Wang and K. A. Goettel, 2007,

27 p.

Portland State University Ondine Residence Hall

seismic rehabilitation demonstration project

(Special Paper 38), by Y. Wang and C. J. Heathman, 2007,

23 p.

Portland State University Montgomery Court

seismic rehabilitation project (Open-File Report 07-

04), by Y. Wang, and C. J. Heathman, 2007, 16 p.

Cascadia Subduction Zone earthquakes: A

magnitude 9.0 earthquake scenario (Open-

File Report 05-05), by Cascadia Region Earthquake

Workgroup, J. Roddey, and L. Clark, 2005, 21 p.http://www.crew.org/PDFs/CREWSubductionZoneSmall.

pd

Map of selected

earthquakes for Oregon,

1841-2002 (Open-FileReport 03-02), by C. A.

Niewendorp and M. E.

Neuhaus, 2003.http://www.oregongeology.

org/sub/earthquakes/images/

EpicenterMap.pd

Earthquake damage in Oregon: Preliminary

estimates of future earthquake losses, (Special

Paper 29), by Y. Wang, and J. L. Clark, 1999, 59 p.

Tsunami hazard zone and evacuation maps onlinehttp://www.oregongeology.org/sub/earthquakes/Coastal/

Tsumaps.HTM

Tsunami hazard assessment of the northern

Oregon coast: A multi-deterministic approach

tested at Cannon Beach, Clatsop County, Oregon

(Special Paper 41), by G. R. Priest, C. Goldnger, K.

Wang, R. C. Witter, Y. Zhang, and A. M. Baptista, 2009, 87

p. plus app., GIS data les, time histories, and animations.

Tsunami Evacuation Building Workshop,

September 28-29, 2009, Cannon Beach, Seaside,

and Portland, Oregon (Open-File Report 10-02), Y.

Wang, complier, 2010, 35 p.

Prehistoric Cascadia tsunami inundation and

runup at Cannon Beach, Clatsop County, Oregon

(Open-File Report 08-12), by R. C. Witter, 2008, 36 p. and

3 app.

Earthquake educational resources

SO U RCEO F EA RTH Q U A K ES

Threesourcescauseear t hquakesi nO regon( Mabeyandot hers, 1993) . Fi rst , shal-low eart hquakes (dept hs of 0-10m i l es) occur onact ivef aul t si nt hecrust . Second,

deeperear t hquakes( dept hsof 10- 31m i les) areassociat edw i tht hesubduct i ng J uandeFucapl at e. Thi rd, deep eart hquakes (dept hs of 31-62m i l es) happenw heret hecont inent al crust andoceanf l oorpl at esarel ockedagai nst eachot herandper i odi -

call ysnap l oose.

TheJ uandeFucapl at ei s asl abof oceanf l oorm ovi ngeast w ardfrom t heJ uandeFucaRi dge, w hi chi sabout 300m i l esof f thecoast l ineof O regonandWas hi ngt on.

Thet erm Cascadi asubduct i onzonew as givent o t hepar t of t hepl at et hat has de-scendedbeneat ht hew est boundcont i nent al crust of w est ernO regon. Eart hquakescanbevery l argei nt hesubduct i onzoneandof t enproducedam agi ng t sunam is.

Thel ast great Cascadi asubduct i onzoneear t hquakehappenedof f t hecoast of O re-gonandWashi ngt oni n1700, w it hanest i m at edm agni t udeof 9.0 . Geol ogi cal evi -dencei ndi cates t hat hugesubduc t i onzoneear t hquakes havest ruck O regon' scoast

every300- 800years, w i tharecordt hat ext ends back at least 11,000 years( A t w at erandot hers, 1995; A t w at erandH em phi l l- H al ey,1997; Gol df inger , 1999) . Theseear thquakes arenot evenl yspacedi nt i m e, andt hecal cul atedaveragei nt erval sbe-

t w eenevents ca n b e lessorm ore. TheCascadi asubduct i onzonei s st il l cont inui ng

t o creep andundoubt edly w est ernO regonw i l l agai nexper i encet heaf f ect sof a

subduct i onzoneear thquake( Shedl ock andWeaver , 1991) .

Theear t hquakes show nont heabovem ap w eret r i ggeredw i t hi nt heEar t h's crust

at dept hs l esst han25m i l es( Jacobson, 1986) . Thel argest of t heseear t hquakesst ruckt hecoast li neof O regonandCal i forni anearBrooki ngs, O regon, onN ovem -ber 23,1873, w it hanest i m at ed 6 . 8m agnit ude. Wong ( 2002) suspect st hat t his

ear t hquakecoul dbeanexcept i onandt hequakew as deeperw i thi nt hedescendi ngJ uandeFuc apl at e.

EA RTH Q U A K ETERMS

A near thquakei s def inedas t he" percept ibl et rem bl ing t ovi ol ent shaki ng of t he

ground, producedby thesuddendi spl acem ent of rocks below t heEar t h's sur face."Rocks respondt o st ress( bei ngsqueezedor pul l edapar t ) near t heEar t h's sur f acebybreaking. Wheret herocks breakandm ove, w ecal l i t af aul t. Thebui l dup of t ecton-

i cf orcesandrel easeof st ressoni ndi vi dual f ault si sw hat causesquakes. H igherstressesl eadt o l argereart hquakes.

Theear t hquake's epi cent er i st heposi t ionont heEar t h's sur facedi rect ly abovet he

f ocusof t heear t hquake. Thef ocus is t hel ocat ionw i t hint heEar t hw hereunder -groundrock m ovesandsends out ear t hquakeenergy w aves. Wef eel t hesew avesasgroundshaki ng. Ear thquakes producet hreem ai nt ypesof energy w aves: P-

w aves(push- pul l w aves), S- w aves( si de- to- sidew aves) , andL- w aves( sur f acew aves) . Eachradi at esf rom t heear t hquakef ocus throught heEar t hat di f f erentrates. Thedi st r ibut i onof ear t hquakesover ti m ei sknow nas sei sm icit y.

Theenergy releasedf rom t heear t hquakei sabasi cquant i t ysci ent i sts havem eas-uredf orm oret hanf i f ty years. Thi senergy rel ease, orm agnit ude, i sm easuredon

t hef am i l iarRi cht erscale, i nvent edby Char l es F. Ri cht er i n1934. Sci ent ist scalcul atet hem agni tudeof t heear t hquakef rom t hel argest sei sm i cw aveor vibrat ion, andaseism ographrecordst hevi brat ions (seism ogram ) that anear t hquakem akes. Ear th-

quakesw i tham agni t udeof about 2 or l essareusual ly call edm i croquakes. Theyarenot usual l yf elt andaregeneral l y recordedonl y onl ocal sei sm ographs. Magni -t ude3 and4ear thquakes arecom m only f el t, but rarel ycausedam age. D am agi ng

groundshaki ng canaccom pany am agnit ude5or 6event , andm ajor dam agecom -m only occursfrom ear t hquakesof m agni t ude7andgr eat er . TheRi cht erscalehasnoupper l im i t. Recent ly, anot her scal ecal ledt hem om ent m agni t udescal ehasbeen

devi sedf or m orepreci sest udy of seism icact i vit y. Mom ent m agni t udei sgeneral lyusednow to descri beear t hquakes, but t hecat egor iesareabout t hesam e.

Ear thquakei nt ensi t yi snot t hesam eas Richt er 'sear t hquakem agni t ude. They arefrequent l yconf usedi nm edi arepor t s. Eart hquakei nt ensi ty descri best hest rengthof shaki ngat a par ti cular place, basedonobservat i ons m adeof bui ldi ng dam age.Thei nt ensit yof anear t hquakei s expressedt oday astheModi f i edMercall i Scale,

devi sedi n1902by Gi useppeMercal li . Thescal eprovi desaser i esof i deali zedde-scr i pt ions of theef f ect sof anear t hquake. I nt ensit y1i s i m percept i bleshaki ng. In-tensi t yi ncreasesby steps to 10, w hichi st ot al destruct ion. Thei nt ensi t yscalere-

qui res noi nstrum ent ati onbecauseany observercanm akeacl assi f icat ion. I tprovides abasi st oest im atet hesi zeof hi st or icear t hquakes. A lso, i t is useful be-causeanear t hquakehas onl ya si ngl em agni tude, but di ff erent int ensi ti escanbe

di st r ibut edt hroughout t heaf f ect edarea.

WH ATDOESTHEMAPSHOW ?

Thism apsho ws o ver 14,000 k no wnearthq uak es fro m1841 to 2002.TheTab leto therig htisa sum m aryo fm ajo r q uak esthathav eaffectedOreg o n,causing g ro undshak inganddam ag e(Wang andClark ,1999).Itsho ws thatOreg o nians facein jury andpro pertydam ag efro mearthq uak eso rig inatingthro ug ho utthePacificNo rthwest.F o r thisreaso n,theOreg o nDe-partm ento fGeo lo g yandMineralReso urcespro ducedthism apo ftheepicenters o fhisto ricearthq uak esinOreg o n,o fftheco ast,andalo ng Oreg o n's b o rderwithso uthernWashing to nandno rthernCalifo rnia. Histo ricpatterns sho w areas i nOreg o nthatareespecially v ulnera-b letoearthq uak es.

Theearthq uak edatasetfo rthis m ap was co m piledfro mtwo so urces:theOreg o nDepart-m ento fGeo lo g y andMineralReso urces' Earthq uak eDatab asefo rOreg o n(Jo hnso nando thers,1994)anddata fro m thePacificNo rthwestS eism o g raphNetwo rk(PNS N)attheUni-v ersity o fWashing to nGeo phy sics Departm ent.Yo ucanv iew andretrieveearthq uak edatainPNS N' searthq uak ecatalo gfro m thefo llo wing web site:

http://www.g eo phy s.washing to n.edu/S EIS /PNS N/CATDAT/welco m e.htm l.

Jo hnso nando thers' (1994)datasetco v eredthearea sho wno nthis m ap.Ho wever,PNS N'scurrentearthq uak ecatalo g co ntainsreco rdsfo r earthq uak eslo catedb etween-125and-117lo ng itudeand42and49latitude.Earthq uak es o utsidePNS N' sco verag earereco rdersold-er thanOcto b er o f1993.Arem ainingtask inpreparing aco m prehensiveearthq uak em ap fo rOreg o nis to inco rpo ratedata fro mo therearthq uak ecatalo g s,particularly tho sethatco v erex trem eeasternandso utheasternOreg o n.Also ,them ag nitudeso fso m eearthq uak es b efo re1962, ro ug hly250 events,weredeterm inedusing intensity data(Jaco b so n,1986).Datao fthisk indareno talway s preciselyaccurate.Thedata reflects po o rly determ inedlo catio nso rm ag nitudes,andareo fteninco m plete.

Earthq uak eepicentersaredisplay edo nthism apas diam o nds andcircles.Thesesy m b o lsareplo ttedatdifferentsizes so as to pro v idea scale.F illeddiam o nds co rrespo ndto anearthq uak ewitha m ag nitudeb etween0 and0.9.Opendiam o ndsrepresentearthq uak eswithm ag nitudes b etween0.9 and3.9.Theco lo redcircles representlarg er m ag nitudeearth-q uak es,tho seo ver3.9.Aleg endex plaining thesesy m b o ls is sho wninthelo werrig htm ar-g ino fthem ap.Theb lack enedareaso nthem aparetheco ncentratio no fm anysy m b o ls.Thisclustering isaresulto fearthq uak eactiv ity thato ccurs inswarm s.Thelarg estearthq uak eina swarm is them ainsho ck ,so m etim es precededb y fo resho ck s,andalm o stalway s fo llo wedb yaftersho ck s.Also ,withino necluster,thereco uldb em any earthq uak eswarm s.

Geo lo g ically activefaults aresho wno nthis m ap (Geo m atrix Co nsultants,1995).Activ e

faultsaredefinedastho sethatm o v edinthelast780,000 y ears.F aults activ einthelast20,000 y ears are co lo r-co dedred.F aults thatm o v edb etween20,000 and780,000 y ears areco lo r-co dedb lue.Aless-than-straig htfo rwardco nnectio nb etweenearthq uak esandactivefaultsex istinOreg o n.Theuncertaintiesinearthq uak elo catio ns canb elarg eandno tallfaultsarek no wn.Oftenthisuncertaintym ak es itdifficultto asso ciateanearthq uak ewithaparticular fault.

Se ismicity Pa tte rnsWecanm ak eso m eg eneralo b serv ations reg arding theseism icity patternssho wno nthism ap.Ov erall,earthq uak es inOreg o nareasso ciatedwithfo ur zo neso fseism icity :theCas-cadeseism iczo ne,Po rtlandHills(Po rtland-Vanco uv er m etro po litanarea),so uth-central(Klam athF alls),andno rtheasternOreg o n.

Ca sca deTheearthq uak esintheCascadeseism iczo neareparto ftheCascadeRang eo fWashing to n,Oreg o n,andCalifo rnia,anactivevo lcanicm o untainchainwherem ag m a ascendsinto thecrustb ecauseo ftheunderly ing sub ductio npro cesses. Thepo rtio no ftheCascadeseism iczo neinso uthwesternWashing to nco ntains theearthq uak e(m ag nitude5.1)trig g ering them ajo rlateralb lastthatrippedawaytheno rthernsideo ftheMo untS t.Helens v o lcano .Theb lastpro b ab ly happened20 to 30 seco ndsaftertheearthq uak eb eg an.Approx im ately 440earthq uak es wereasso ciatedwiththe1980 eruptio no fMo untS t.Helens.

Inaty picaly ear, o netoseveral,sho rt-liv edswarm so fsm allearthq uak esarereco rdedo ntheso uthflak eandb elo w thesum m ito fMo untHo o dv o lcanoinOreg o n.Theseswarm spro b ab ly represents a reactio nto reg io naltecto nicstresses,no tpre-eruptio nv o lcanicactiv ity .

Portla ndH illsAscattered,no rthwest-trending cluster o fearthq uak es,calledthePo rtlandHills seism icityzo ne,lies inthePo rtland-Vanco uv er m etro po litanarea (Blak ely ando thers,1995). No tab leearthq uak es inthis zo neincludedthe4.7m ag nitudeearthq uak eo nNo v em b er 7,1961 andtheNo v em b er5, 1962,earthq uak eo f5.5 m ag nitude.ThePo rtlandHillsseism icity zo neis ina po rtio no fno rthwesternOreg o nshearedintoa series o fjux atapo sedb lo ck smoving indif-ferentdirectio ns.

Mo v em ento ftheb lock sinduces earthq uak es alo ng no rthwest-andno rtheast-trendingfaultzo nes.Twohav eparticularsig nificance: theno rthno rthwest-trendingPo rtlandHillsandtheMo untAng el-Gales Creek faultzo nes. ThePo rtlandHills faultcanb etracedthroughdo wnto wnPo rtlandandthefaultm ay b ea reaso nfo r t heunusually steepscarpo fPo rt-land's WestHills.To thewest,theMo untAng el-Gales Creek faultzo neis asing le, po tential-lyactiv efaultsy stem thathas b eenm appedfro m theCascades i ntotheWillam etteValleythro ug htotheCo astRang e(Do ug herty andTrehu,2002).The5.6 m ag nitudeMarch25,

1993,S co ttsMills(near S ilv erto nandWo odb urninMario nCo unty ,Oreg o n)earthq uak ewithanepicenternearMo untAng el, inMario nCo unty ,Orego n,m ay b easso ciatedwiththisfaultzo ne(Madinando thers,1993). Other activefaultsintheWillam etteValley ,no less sig -nificant,canpro ducefutureearthq uakes as well.

South-Ce ntralO re gonThedenseclustero fearthq uak es inso uth-centralOreg o nisasso ciatedwiththeS eptem b er20,1993,earthq uak eso f5.9and6.0m ag nitude(Wiley ando thers,1993).Aftersho ck s as larg easm ag nitude5.1 co ntinuedto disturb residentsfo r six months (S herro dando thers,1997).Epicenters fo r theseearthq uak es arenearno rth-to no rthwest-trending faults ab o ut19m ilesno rthwesto fKlam athF alls.Quak es inthis area arerelatedto theno rthernm o stparto ftheBasinandRang eg eo lo gicpro v ince,a v astareaex tending fro m so uth-centralOreg o nto Ari-zona andenco m passing m o sto fNev ada.TheBasinandRang einso uth-centralOreg o nisstretchinginaneast-westdirectio ncausing thecrustto b reak into b lo ck s alo ng steeply dip-ping faults(Wo ng andBo tt,1995;Wells ando thers,1998).Earthq uak es suchas tho senearKlam athF allsandtheearthq uak eswarmnear theto wno fAdel(m ag nitude5.1)to theeasto fLak ev iewwerepro b ab ly trig g eredasthecrustb ro k ealo ng ex istingfaults.

Northe a ste rnO re gonInno rtheasternOreg o n,sev eraldiffuseareas o fseism icity fallo ntheOreg o n-Washing to nb o rder. Thearea near Milto n-F reewater wasthesiteo fthe1936 m ag nitude6.4 earthq uak e.This earthq uak eandthescatteredseism icity inthereg io narerelatedto theOly m pic-Wallo -walineam ent. Thelineam entisa b ro adzo neo fno rthwest-trendingfaultsandinterv ening

b asinsandupliftsstretching fro m theOly m picMo untains o fwesternWashing to nacro ss theCascades andCo lum b ia Basininto theno rtheastsideo ftheWallo waMo untainsinno rtheast-ernOreg o n.

REFERENCES

A t w at er, B. F., N el son, A .R., Cl ague, J .J ., Carver, G. A ., Yam aguchi , D .K., Bobrow sky, P.T., Bourgeoi s, J .,

D ar ienzo, M.E. , Grant , W.C. , H em phil l- H aley, E., Kel sey, H .M. J acoby, G . C . ,N i shenko,S.P. , Pal m er , S.P. ,Pet erson, C.D ., a n d R ei nhar t , M.A ., 1995, Sum m ary of coast al geol ogicevi dencef or past great ear t hquakes att heCascadi a subduct i onzone: Ear thquakeSpect ra, Vol . 11, no. 1, p. 1- 18.

A tw at er, B . F . ,andH em phi l l- H all ey, E., 1997, Recurrencei nt erval sf orgreat ear thquakes of t hepast 3,500yearsat nor t heasternWi l lapaBay: U .S. Geol ogi cal Survey Prof essi onal Paper , 108.

Bl akel y, R.J ., Wel ls, R . E . ,Yeli n, T.S. , Madi n, I. P . ,andBeeson, M.H ., 1995,Tect oni cset ti ngof t hePor t land- Vancouver area, O regonandWashi ngt on: Const rai nts f rom l ow - al ti tudeaerom agnet i cdat a:Geol ogi cal Societ yof A m eri ca, Vol . 107, no. 9, p. 1051-1062.

Brant ley andTopi nka, 1984, Vol cani cSt udi esat t heU . S. Geol ogi cal Survey' sD avidA . J ohnst onCascadesVol cano O bservatory, Vancouver , Washi ngt on:Ear thquakeI nf orm at ionBul l et i n, Vol .16, no. 2, March-A pr il

1984.

D ougher ty, M.L. , andTrehu, A .M., 2002, N eogenedef orm ati onof t heMt . A ngel/Gal es CreekFaul t Zone:

Const raint sf rom hi gh-resol uti onsei sm i cref lect ioni m agi ng: U SGSEar t hquakeH azardsReduct i onProgramA nnual Sum m ar i esof Techni cal Repor t s, Vol . 37.

Geom at ri x Consul tant s, Inc., 1995, Final Repor t , Sei sm i cD esi gnMappi ng, St at eof O regon: January, O D O T

Project N o. 2442, 5secti ons, 4appendi ces, 5pl at es.

Gol df inger , C. , McCaf frey, R., Murray, M., Zw ick, P., N abel ek,J., Sm it h, C.L. , andJ ohnson, C., 1999, GPS

constrai nts onplat ecoupl ing i ncent ral w est ernO regon[ abs.] : Sei sm ologi cal ResearchLet t ers, v. 70,p. 244- 245.

J ohnson, A .G., Scofi eld, D .H ., Madin, I .P. , 1994, Ear thquakedat abasef or O regon, 1833 throughO ct ober 25,1993:O regonD epar t m ent of Geol ogy andMi neral I ndust r ies O pen- Fi leRepor t O - 94- 4, 1di skett e.

Madi n, I.P. , Pr i est, G. P., Mabey, M.A ., Malone, S., Yel in, T.S. , andMei er , D ., 1993, March25, 1993, Scot t sMil l s

ear thquake- - w est ernO regon' sw ake-up cal l: O regonD epar t m ent of Geol ogy andMi neral Indust r i es, O regonGeol ogy, Vol . 55, no. 3, May1993.

Shedl ock, K.M., andWeaver , C. S., 1991, Program f orear t hquakehazards assessm ent i nt hePaci f i cN or thw est:U .S. Geol ogi cal SurveyCi rcul ar1067, 29pgs.

Sherrod, D . R . ,Mast in, L. G. , Scot t, W.E. , andSchi l l ing, S.P. , 1997, Vol cano H azards at N ew berry Vol cano,O regon:U SGSO pen- Fi leRepor t 97- 513.

Wang, Y., andCl ark, J .L. , 1999, Ear thquakedam agei nO regon: Prel i m i naryest im ates of fut ureear t hquakeslosses: O regonD epar t m ent of O regonandMi neral Indust r i esSpecial Paper 29, p. 13.

Well s, R.E. , Weaver , C.S. , andBl akel y, R.J . , 1998, Fore-arcm i grat i oni nCascadi aandi t s neot ect oni csigni f icance:Geol ogy, 26, p. 759- 762.

Wil ey, T.J ., Sherrod, D .R., Keef er , D . K . ,Q am ar ,A .,Schust er , R.L. , D ew ey,J .W., Mabey, M.A ., Black, G. L., andWell s, R.E. , 1993, Kl am athFal l sear thquakes, Septem ber20, 1993- -i ncludi ng t hest rongest quakeeverm easuredi nO regon: O regonD epar tm ent of Geol ogy andMi neral I ndust ri es, O regonGeol ogy, Vol . 55, no. 6,

p. 127- 136.

Wong, I .G. , andBot t , J .D .J , 1995, A look back at O regon'seart hquakehi st ory, 1841-1994: O regonD epar t m ent ofGeol ogy andMi neral I ndust ri es, O regonGeol ogy, Vol . 57, no. 6, p. 125-139.

Wong, I .G. , 2002, I ntrapl ateear t hquakepot ent i al i nt heCascadi a Subduct ionZonebeneat hw est ernO regon[ abs] : Geol ogical Soci ety of A m er icaA bst ract w i thProgram s.

H istor icalEar thquakesaf fectingO regon

D at e Locati on Magnit u d e C o m m en ts

Appr oxi m ateyears

600BCE

Of fs hore,Cas cadi a

s ubducti onzone1

Pr obabl y

8- 9

Res ear cher s Bri an At w at er and

Ei leenH em phil l- H al eyhavedated

Bay,Was hi ngton;t hes earet hem idpoints of t heager angef or t hes es i xevents .

Of fs hore,Cas cadi as ubducti onzone1

Approx-im at el y9

Generat ed a ts unam it hat s tr uckOr egon,Was hingtonandJ apan;des tr oyedN at iveAm eri can vi ll agesal ongt hecoas t.

N ovem ber 23,1873

Or egon/Cali for m iabor der ,near

Br ooki ngs

6. 8 F e l t as far aw ayasPor tl andand SanFr anci sco;m ayhavebeenan

i ntr aplateevent becauseof lackofaf ters hocks .

July15,193 6 M i lt on- Freew at e r 6. 4 T w o for es hocks andm any

af ters hocks f el t;$100,000dam age( in1936dol lar s) .

Apr il 13,1 9 4 9 O l ym pi a,Washi ngt on1

7.1 Ei ght deaths and$25m ill iondam age( in 1949doll ar s );cr ackedplas ter ,ot her m i nordam agein nor thw es tOr egon.

N ovem ber 5,1962

Por tl and/Vancou v e r 5. 5 S h a k ingl as t edup t o30s econds;chi m neys cracked,w indow sbr oke,f urni tur em oved.

1968 A de l 5 . 1 S w ar m l ast ed M aythr oughJ uly,decreasi ngin i ntens ity;i ncreas edf low atahot s pr ingw as r epor ted.

Apr il 12,1976N ear M aupi n 4. 8 S o u n d sdes cri bedas dis t ant thunder,s onicboom s ,ands tr ong w ind.

Apr il 25,1 9 9 2 C a peM endocino,Cali for nia1

7. 0 S u b d u ct ioneart hquakeatt hetr ipl e-junct ionof theCas cadias ubduct ionzoneandtheSanAndreas andM endocinof aul ts .

M ar ch25,19 9 3 S c ot ts M il l 5. 6 O nM ount Angel- Gales Creekfault ;$30m i ll iondam age,i ncludi ngM olall aH i gh School andM ountAngel chur ch.

Septem ber 20,1993

Klam at hFal ls 5. 9and6.0Tw ode at hs ,$10m il liondam age,i ncl udingcount ycour thous e;r ockf alls i nducedbygroundm ot ion.

ear thquakes andt s unam i satWil lapa

J anuary 26,1700

400,750,900

1400BCE1050BCE

6.8N earO lym pi aWashi ngt on1

February28,2001

A bout 400injur i es,$2 to 3.9 bil liondam agei nt heSeatt le/Tacom aarea.Fel tarea: VancouverBC,N or thw estO regon,Sal tLakeCi tyU T.

1not show nont hem ap

D allas

Eugene

N ew por t

Fossil

C ondon

Moro

TheD alles

H ood R iver

McMinnvill e

O r egon C it y

Madras

Por tland

Saint H elens

Til lamook

H illsboro

Ast or ia

Ent erpr ise

La G rande

Baker

Val e

Burns

C anyonC it y

Pendl et on

H eppner

G old BeachG rantsPass

C oquill e R osebur g

LakeviewKlamat h Falls

Medf or d

Bend

Pr inevill e

C or val lis

Albany

Sal em

C ount yseat

C ount yline

St at eli ne

Faul t - Lat e quater nar y

Faul t -H olocene

Magnit ude 0. 0-0. 9






Magnit ude 7 andhigher

N EVAD AC ALI FO R N I A

N EVAD AID AH O

I D AH OWASH I N G TO N

CURRY

BAKER

JOSEPHINE

KLAMATH

COOS

DESCHUTES

CROOK

HARNEY

LAKE

MALHEUR

UNION

UMATILLA

WALLOWA

GRANTLINN

WASCO

SHERMAN

HOODRIVER

GILLIAM

MORROWCLACKAMAS

JEFFERSON

WHEELER

TILLAMOOK

LINCOLN

BENTON

POLK

COLUMBIA

CLATSOP

JACKSON

MARION

LANE

WASHINGTON

MULTNOMAH

YAMHILL

DOUGLAS

TheN atureof theN or thw est Inf ormation C enter 800N EO r egonSt r eet #5

Por t land, O R97232503/872-2750 w w w . nat ur enw .org

andtheBakerC it y(541-523-3133)andG rants

Pass(541-476-2496), Field O f f icesof the O r egonD epar t mentof G eologyandMiner al Industr ies

Th is m a p

is

a v ai l a b

le f r o m :

OPEN-FILE REPORT 03-02

MapofSel ectedE arthquakes f orO regon,1841 through2002

B yC l ark A . Niew endorpandMark E . Neuhaus

ISSN0270-952X

MapofSelectedEarthquakes forOregon,1841 through2002

2003

STA TE O FO R E G O ND E PA R TME NT O F G E O LO G Y A ND MINE R A LIND USTR IE S

V IC K IS. McC O NNE LL, A C TING STA TE G E O LO G IST

126 12 2123124125 12 012 1 1 19 1 171 18 1 16

42

45

46

44

DOGAMI Earthquake and Tsunami PublicationsEarthquake Preparedness

American Red Crosshttp://www.redcross.org/

Federal Emergency Management Agency (FEMA)http://www.ema.gov/

NOAA West Coast and Alaska Tsunami Warning

Centerhttp://wcatwc.arh.noaa.gov/

Are You Ready? An In-depth Guide to Citizen

Preparedness by FEMAhttp://www.ema.gov/areyouready/

Quake Safe Schools (Oregon Department of

Education)

http://www.ode.state.or.us/go/quakesaeschools/

FEMA 395, Incremental Seismic Rehabilitation of

School Buildings (K-12)http://www.ema.gov/library/viewRecord.do?id=1980

Oregon Emergency Management (OEM) Seismic

Rehabilitation Grant Programhttp://www.oregon.gov/OMD/OEM/plans_train/SRGP.

shtml

Oregon Building Codes Divisionhttp://www.cbs.state.or.us/bcd/

Earthquake Science

Pacic Northwest Seismic Network (PNSN)http://www.pnsn.org/

U.S. Geological Survey Oregon Earthquake

Informationhttp://earthquake.usgs.gov/earthquakes/

states/?region=Oregon

National Earthquake Hazards Reduction Program

(NEHRP)http://www.nehrp.gov/

Earthquake Organizations

Oregon Seismic Safety Policy Advisory

Commission (OSSPAC)http://www.oregon.gov/OMD/OEM/osspac/osspac.shtml

Western States Seismic Policy Council (WSSPC)http://www.wsspc.org/

Oregon Partnership for Disaster Resiliencehttp://opdr.uoregon.edu/

Cascadia Region Earthquake Workgroup (CREW)http://www.crew.org/index.html

Fact Sheet: Tsunami hazards

in Oregon, 2008, 4 p.http://www.oregongeology.org/pubs/

s/tsunami-actsheet_onscreen.pd

Fact Sheet: TsunamiReady,

TsunamiPrepared: Oregon

Coast-Wide National Tsunami

Hazard Mitigation Program,

2010, 2 p.http://www.oregongeology.org/pubs/s/

TsunamiPreparedFactSheetAlt-12-28-09.pd

Tsunami Hazards in OregonOregonGeology

Fact Sheet

OregonDepartmentofGeologyand MineralIndustries800NEO regonSt.,Suite965Portland,OR 97232971-673- 1555 www.OregonGeology.orgORE

G

ON

DEPA R

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19 3 7LASTUPDATED04-03-2009PRINTEDONRECY CLEDPAPER

What isa tsunami?

A tsunami is aseries o ocean waves mostoten generatedbydisturbances o theseafoor duringshallow, underseaearth-quakes. Less commonly, landslides andvolcaniceruptions cantrigger atsunami. In thedeepwater o theopen ocean, tsunamiwaves can travel atspeeds upto800 km (500 miles)per hourandareimperceptibletoships becausethewaveheightis typi-callyless than aeweet.

As atsunami approaches thecoastitslows dramatically, butits heightmaymultiplybyaactor o 10 or moreandhavecata-strophicconsequences topeoplelivingatthecoast. As aresult,peopleon thebeach, in low-lyingareas o thecoast, andnearbaymouths or tidal fats acethegreatestdanger rom tsunamis.

A tsunami can betriggeredbyearthquakes aroundthePacicOcean includingunderseaearthquakes with epicenters locatedonlytens o miles oshoretheOregon coast. Over thelastcen-tury, waveheights o tsunamis in the PacicOcean havereachedupto13.5 m (45 t)abovetheshorelinenear theearthquakesource. In aewrarecases, local conditions ampliedtheheighto atsunami toover 30 m (100 t).

What isthe diference betweena Cascadia (local) tsunamianda distant tsunami?

An earthquakeon theCascadiaSubduction Zone, a960-km-long(600 mile)earthquakeaultzonethatsits othePacicNorthwestcoast, can createa Cascadiatsunamithatwill reachtheOregon coastwithin 15 to20 minutes. Massiveearthquakeso magnitude9 or greater thatcan lastor several minutes havebeen generatedon theaultzone. A destructivetsunami can ol-lowmoments later.

A distanttsunamiproducedbyan earthquakear rom Or-egon will take4 or morehours totravel cross thePacicOcean,usuallyallowingtimeor an ocial warningandevacuation, inecessary. A distanttsunami will besmaller in sizeandmuchless destructive, butitcan still beverydangerous.

Destruction a tSea sid e,Oreg on,d ue tothe Ma rch 28,1964,Ala ska tsuna mi.Wa ter lifted theca r a g a instthe house,uprooted the tree,a nd wa shed in d riftwood log s.Bea chgrasshangingin the tree branchesindicatesthe maximum water depth atthislocat ion was3.5 m (12 ft).Thishouse was12 00 m (4000ft) from the shore.(Photosource:Herb Schla ppi)

Tsunami Generation

TheDecember 26,2004, Indian Ocean tsunamistrikesKha oLa k,Tha ila nd .A wa llof wa terd wa rfsa tourista nd boa tsonthe bea ch.(Photosource:John Ja ckieKnill fa mily photo/AP)

(Source:U.S.Geolog ica l Survey Circula r 1187)

VerticalSlice Through aSubduction Zone

One ofthe m any tectonicplatesthatm ake upEarthsoutershelldescends,or subducts, underan adjacentplate.Thiskindofboundary between

platesiscalleda subduction zone. When theplatesm ove suddenly in an areawherethey areusually stuck,an earthquake happens.

sekauqhtraEneewteB

gnidirrevoeht,etalpgnitcudbusehtotkcutSplategetssqueezed.Itsleading edge isdraggeddown,while an areabehindbulgesupward.This

,seirutnecrosedacedrofnoseogtnemevomslowly building upstress.

ekauqhtraEnagniruD

sneppahenoznoitcudbusagnolaekauqhtraenAwhen theleading edge of the overridi ng plate

aesehtgnisiar,drawaessgnirpsdnaeerfskaerb

oorandthe waterabove it.Thisupliftstartsatsunam i.Meanwhile,the bulge behindthe leadingedge collapses,thinning the plate andlowering

coastalareas.

M inutesLater

Partofthe tsunam iracestowardnearby land,rehtonA.erohsotnisemoctisarellatgniworg

partheadsacrossthe ocean towarddistant

shores.
http://www.oregongeology.org/http://www.oregongeology.org/sub/publications/IMS/ims.htmhttp://www.oregongeology.org/sub/publications/IMS/ims.htmhttp://www.oregongeology.org/sub/projects/rvs/default.htmhttp://www.oregongeology.org/sub/projects/rvs/default.htmhttp://www.crew.org/PDFs/CREWSubductionZoneSmall.pdfhttp://www.crew.org/PDFs/CREWSubductionZoneSmall.pdfhttp://www.oregongeology.org/sub/earthquakes/images/EpicenterMap.pdfhttp://www.oregongeology.org/sub/earthquakes/images/EpicenterMap.pdfhttp://www.oregongeology.org/sub/earthquakes/images/EpicenterMap.pdfhttp://www.oregongeology.org/sub/earthquakes/Coastal/Tsumaps.HTMhttp://www.oregongeology.org/sub/earthquakes/Coastal/Tsumaps.HTMhttp://www.redcross.org/http://www.fema.gov/http://wcatwc.arh.noaa.gov/http://www.fema.gov/areyouready/http://www.ode.state.or.us/go/quakesafeschools/http://www.fema.gov/library/viewRecord.do?id=1980http://www.oregon.gov/OMD/OEM/plans_train/SRGP.shtmlhttp://www.oregon.gov/OMD/OEM/plans_train/SRGP.shtmlhttp://www.pnsn.org/http://earthquake.usgs.gov/earthquakes/states/?region=Oregonhttp://earthquake.usgs.gov/earthquakes/states/?region=Oregonhttp://www.nehrp.gov/http://www.oregon.gov/OMD/OEM/osspac/osspac.shtmlhttp://www.wsspc.org/http://www.crew.org/index.htmlhttp://www.oregongeology.org/pubs/fs/tsunami-factsheet_onscreen.pdfhttp://www.oregongeology.org/pubs/fs/tsunami-factsheet_onscreen.pdfhttp://www.oregongeology.org/pubs/fs/TsunamiPreparedFactSheetAlt-12-28-09.pdfhttp://www.oregongeology.org/pubs/fs/TsunamiPreparedFactSheetAlt-12-28-09.pdfhttp://www.oregongeology.org/pubs/fs/TsunamiPreparedFactSheetAlt-12-28-09.pdfhttp://www.oregongeology.org/pubs/fs/TsunamiPreparedFactSheetAlt-12-28-09.pdfhttp://www.oregongeology.org/pubs/fs/tsunami-factsheet_onscreen.pdfhttp://www.oregongeology.org/pubs/fs/tsunami-factsheet_onscreen.pdfhttp://www.crew.org/index.htmlhttp://www.wsspc.org/http://www.oregon.gov/OMD/OEM/osspac/osspac.shtmlhttp://www.nehrp.gov/http://earthquake.usgs.gov/earthquakes/states/?region=Oregonhttp://earthquake.usgs.gov/earthquakes/states/?region=Oregonhttp://www.pnsn.org/http://www.oregon.gov/OMD/OEM/plans_train/SRGP.shtmlhttp://www.oregon.gov/OMD/OEM/plans_train/SRGP.shtmlhttp://www.fema.gov/library/viewRecord.do?id=1980http://www.ode.state.or.us/go/quakesafeschools/http://www.fema.gov/areyouready/http://wcatwc.arh.noaa.gov/http://www.fema.gov/http://www.redcross.org/http://www.oregongeology.org/sub/earthquakes/Coastal/Tsumaps.HTMhttp://www.oregongeology.org/sub/earthquakes/Coastal/Tsumaps.HTMhttp://www.oregongeology.org/sub/earthquakes/images/EpicenterMap.pdfhttp://www.oregongeology.org/sub/earthquakes/images/EpicenterMap.pdfhttp://www.oregongeology.org/sub/earthquakes/images/EpicenterMap.pdfhttp://www.crew.org/PDFs/CREWSubductionZoneSmall.pdfhttp://www.crew.org/PDFs/CREWSubductionZoneSmall.pdfhttp://www.oregongeology.org/sub/projects/rvs/default.htmhttp://www.oregongeology.org/sub/projects/rvs/default.htmhttp://www.oregongeology.org/sub/publications/IMS/ims.htmhttp://www.oregongeology.org/sub/publications/IMS/ims.htmhttp://www.oregongeology.org/


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NATURE O THE NORTHWEST PUBLICATION ORDERSMark desired titles on the list above and ll out this form. A complete list of publications is on the Nature of the Northwest home page:

http://www.NatureNW.org. You can order directly from the website or send this order form to The Nature of the Northwest Information

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Publications available now rom

A complete list of DOGAMI publications can be found online atwww.OregonGeology.org.

Use the order form below or log on to www.NatureNW.org to order.

Volcanoes and Earthquakes,

by Ken Rubin,

Simon and Schuster, New York,2007, 64 p., $16.95.

Brings volcanoes and earthquakes to life,

with the most up-to-date informationand state-of-the-art 3-D illustrations that

practically leap o every page, stimulating

minds and imaginations in a whole new way.

Oregons Greatest Natural

Disasters, by William L. Sullivan,

Navillus Press, Eugene, Oregon,2008, 263 p., $18.95.

The cycles behind the states historic

earthquakes, tsunamis, eruptions,

oods, and res and how they

are changing.

The Orphan Tsunami of 1700Japanese Clues to a

Parent Earthquake in North America, U.S. Geological

Survey Professional Paper 1707, by Brian Atwater andothers, 2005, 144 p., 325 illus, paperback, $24.95.

Tells the scientic detective story of the tsunami through

clues from both sides of the Pacic. Also available as a

PDF le: http://pubs.usgs.gov/pp/pp1707/pp1707.pdf

Living With Earthquakes in the

Pacic Northwest: A Survivors

Guide, 2nd ed., by Robert S.

Yeats, Oregon State UniversityPress, Corvallis, 2004, 390 p.,

$22.95.

Describes the threat posed by theCascadia Subduction Zone fault.

Preparedness Now! An Emergency

Survival Guide, revised ed., byAton Edwards, Process Media, Self-

Reliance Series, Port Townsend,

Wash., 2009, 343 p., $16.95.Guide for those who want to live more

self-suciently and learn how to

prepare for emergencies and disasters.

Nature of the Northwest Information Center

Suite 965, 800 NE Oregon Street

Portland, OR 97232-2162

phone (971) 673-2331, fax (971) 673-1562
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12/1212 CASCADIA Wi 2010


Places to see: University building seismic mitigation

L b t O l t O G l

Portland area places to see:

Ondine Residence Hall, PSU;

TriMet Washington

Park/Zoo station

Oregon is at risk for a major earthquake. In

addition to the Cascadia Subduction Zonethreat, many communities have active

crustal faults nearby. One major success ofthe 2001 laws to better prepare and protect

Oregonians from future earthquake losses(see p. 5) is requiring life-safety in publicuniversity buildings.

The states goal is to increase aware-ness and promote preparedness through

demonstration projects such as the one atOndine Hall, Portland State University (PSU).

Demonstration projects create momentumin earthquake preparedness throughout

the state by providing an impetus for in-dividual owners and communities to con-

duct similar seismic retrot projects.

As part of a long-term, 7-campus-wide,seismic mitigation plan, DOGAMI devel-

oped a 6-step method for evaluating build-ings for seismic risk. Out of about 1,000

buildings evaluated using this method,the Oregon University System (OUS) andDOGAMI identied ve demonstration

projects as part of the initial Seismic RiskManagement Program, which began in

2005: Montgomery Court and Ondine Resi-dence Hall, Portland State University; Snell

Hall Administration Building, Oregon Insti-tute of Technology; Humanities and Social

Sciences, Western Oregon University; andNash Hall, Oregon State University. Many

other university buildings have serious

seismic deciencies and are slated to beseismically strengthened via the long-term

comprehensive mitigation plan. The plan isdriven by the seismic life-safety risk index

coupled with deferred maintenance needsand energy eciency improvements.

Related DOGAMI publications: SP-39, Enhanced

rapid visual screening (E-RVS) for prioritization o

seismic retrots in Oregon; SP-38, Portland State

University Ondine Residence Hall seismic reha

bilitation demonstration project; O-07-04, Port

land State University Montgomery Court seismic

rehabilitation project.

Cross-bracing (far

left) and, steel plate

wall floor-to-floor

connections (left) are

some visible resultsof the PSU Ondine

residence hall seismic

mitigation effort.

Portlands TriMet Washington Park/Zoo

light-rail (MAX) station (Red/Blue lines) isthe deepest tunnel station in North Ameri-

ca at 260 feet. The public art on the stationplatform includes a geologic time line and

drill core from one of the many geotechni-cal borings made along the tunnel route.

This is the most accessible and completeexposure of Portland geology in exis-tence. Visitors can walk along the core as

it traverses Columbia River Basalt, BoringLava, and loess.

To learn more about Portlands geolo-gy, including faults, see the eld trip guide

Portland, Oregon, geology by tram, train,and foot by Ian P. Madin (http://www.oregongeology.org/pubs/og/OGv69n01-

PDXtram.pdf).

Places to see: Geologic time line at Portland TriMet station
http://www.oregongeology.org/http://www.oregongeology.org/http://www.oregongeology.org/pubs/og/OGv69n01-PDXtram.pdfhttp://www.oregongeology.org/pubs/og/OGv69n01-PDXtram.pdfhttp://www.oregongeology.org/pubs/og/OGv69n01-PDXtram.pdfhttp://www.oregongeology.org/pubs/og/OGv69n01-PDXtram.pdfhttp://www.oregongeology.org/pubs/og/OGv69n01-PDXtram.pdfhttp://www.oregongeology.org/pubs/og/OGv69n01-PDXtram.pdfhttp://www.oregongeology.org/http://www.oregongeology.org/

oregon’s earthquake risk and resiliency (oregon department of geology and mineral industries)

Documents