Utah Seismic Safety CommisionUtah Division of Emergency ManagementUtah Geological SurveyUniversity of Utah Seismograph StationsStructural Engineers Association of UtahU.S. Geological SurveyFederal Emergency Management Agency

Utah Seismic Safety Commission, 2008Salt Lake City, UtahAny use of trade, product, or firm names in this publicationis for descriptive purposes only and does not implyendorsement by the State of Utah or U.S. Government.Printed by the Utah Geological Survey, 2014Third PrintingFor additional copies, contact:Natural Resources Map & Bookstore1594 W. North TempleSalt Lake City, Utah 84116Phone (801) 537-3320, toll-free (888) UTAH MAPEmail: geostore@utah.govhttp://mapstore.utah.govThis report and any updates are available at: approved for publication, October, 2008This document is adapted from California editions of“Putting Down Roots in Earthquake Country,” originallywritten by Lucy Jones (U.S. Geological Survey [USGS])with later revisions by Mark Benthien (Southern CaliforniaEarthquake Center [SCEC]) and others, first published bySCEC in 1995 and updated yearly since 2004. The bookletwas first adapted for the San Francisco Bay Region in 2005by Mary Lou Zoback (USGS) and others, and published bythe USGS. See all versions.Disclaimer: The suggestions and illustrations includedin this document are intended to improve earthquakeawareness and preparedness; however, they do notguarantee the safety of an individual or a structure. Thewriters, contributors, and sponsors of this handbook do notassume liability for any injury, death, property damage, orother effect of an earthquake.Prepared by the Utah Seismic Safety Commission (USSC),Utah Geological Survey (UGS), Utah Division of EmergencyManagement (UDEM), University of Utah SeismographStations (UUSS), and Structural Engineers Association ofUtah (SEAU), in cooperation with the U.S. Geological Survey(USGS) and Federal Emergency Management Agency(FEMA).Contributors: UGS—Gary Christenson, ChristopherDuRoss, Sandra Eldredge, Michael Hylland; UDEM—RobertCarey; UUSS—Walter Arabasz, Kristine Pankow; SEAU—Barry Welliver.Reviewed by: University of Utah— Relu Burlacu, Lee Siegel;USGS— Tom Brocher, Anthony Crone, Mark Petersen;FEMA—Doug Bausch; SCEC—Mark Benthien.Production, design, and illustration by: Liz Paton andStevie Emerson (UGS) based on template for the SanFrancisco Bay Region version of this handbook by SusanMayfield (USGS).ContentsIntroductionUtah is “Earthquake Country”.................................................................................1Why Should I Care?—Utah is Your HomeUtah and the Intermountain West are Seismically Active.......................................2Most of Utah’s Populated Area Lies Within an Active Earthquake Belt....................4Utah Faces a Dual Earthquake Threat—and Earthquakes inUtah Aren’t Just a Wasatch Front Problem..............................................................5The Wasatch Fault..................................................................................................6Most Earthquake Damage is Caused by Shaking....................................................8Earthquakes Also Cause Damage in Other Ways...................................................10Why Should I Prepare?—Big Quakes will Affect YouResponse of Buildings to Earthquakes..................................................................12The ABCs of Seismic Building Codes.....................................................................13Utah’s People, Economy, and Infrastructure Are IncreasinglyVulnerable to a Wasatch Fault Earthquake...........................................................14Your Life Could Change Unexpectedly in the Next Quake.....................................16Your Financial Situation Could Be Affected by a Quake.........................................18What Should I Do?—7 Steps to Earthquake SafetyThe Seven Steps to Earthquake Safety.................................................................20STEP 1—Identify Potential Hazards in Your Home and Begin to Fix Them...........22STEP 2—Create a Disaster-Preparedness Plan.....................................................24STEP 3—Prepare Disaster Supply Kits.................................................................25STEP 4—Identify Your Building’s Potential Weaknesses and Begin to Fix Them...26STEP 5—Protect Yourself During Earthquake Shaking.........................................28STEP 6—After the Earthquake, Check for Injuries and Damage...........................29STEP 7—When Safe, Continue to Follow Your Disaster-Preparedness Plan.........30What Else Should I Know?A Review of Money Matters: Financial Impacts of Earthquakes............................31Earthquake Information on the Web....................................................................32Glossary...............................................................................................................33Other illustrators: Pat Bagley (front cover and pages 1,15, 18, 22); from San Francisco Bay Region version of thishandbook (USGS), Todd Connor (pages 22, 23, 29).

INTRODUCTIONUtah is “Earthquake Country”This handbook provides information about the threat posed by earthquakes inUtah, particularly along the Wasatch Front, and explains how you can preparefor, survive, and recover from these inevitable events. If you live or work inUtah, you need to know why you should be concerned about earthquakes,what you can expect during and after an earthquake, and what you need to dobeforehand to be safe and protect your property.Much has been learned about theearthquake threat and vulnerabilityin Utah:We know earthquakes occur hereUtah has experienced sixteen earthquakesgreater than magnitude 5.5 sincepioneer settlement in 1847, and geologicstudies of Utah’s faults indicate a longhistory of repeated large earthquakesof magnitude 6.5 and greater prior tosettlement. Utah is not on a boundarybetween tectonic plates where mostof the world’s earthquakes occur, butrather is in the western part of the NorthAmerican plate. However, earthquakesin Utah are indirectly caused by interactionswith the Pacific plate along theplate margin on the west coast of theUnited States. Also, many small earthquakesin east-central Utah are inducedby underground coal mining.We know where earthquakes are likelyto occur and what they can doLarge, damaging earthquakes in Utahare most likely to occur in a belt thatextends north-south through thecenter of the state (page 4), essentiallyfollowing Interstate Highway 15, wherethere are many active faults capable ofproducing earthquakes. Moderate tolarge earthquakes (generally magnitude6 and greater) can kill and injuremany people and cause substantialdamage to buildings, roads, bridges,and utilities.We know how to reduce losses infuture large earthquakesMost casualties and economic lossesresult from damage to poorly constructed,older buildings and their unrestrainedcontents. Improved buildingcodes are now in force statewide, someolder buildings have been strengthened,and steps are being taken to upgradeschools and other critical facilities. SomeUtah residents have secured their homesto better withstand shaking, createdemergency plans and disaster supplykits, and held home earthquake drills.BUT we have not done enoughto be prepared for the next largeearthquake:Few households have disaster plansIf an earthquake occurred right now,where would you go to be safe? If youare at work and your children are atschool when the earthquake occurs,how will you get back together?Few households have disastersupply kitsYou will likely be on your own withoutvital services in the hours and days followingan earthquake. Are you preparedwith water, food, first aid supplies, andmedications?Few owners have taken steps toretrofit their older homesUtah has many houses that predate modernearthquake building codes. Is yourhome bolted to its foundation? If youlive in an older building, has it been retrofitted?Is your water heater strapped?Could unsecured furniture or objects falland cause injury or damage?Many earthquake-vulnerable homes andbuildings exist in Utah, placing occupants atrisk. The State of Utah reconstructed the StateCapitol Building to preserve a historic buildingand to ensure public safety and continuityof government in the event of a largeearthquake. (Photo courtesy of UGS, taken onSeptember 24, 2006)Don’t be fooled!—Myth number 1“WHAT EARTHQUAKE HAZARD?”Many Utah residents discount the earthquakehazard based on the near absence of moderateto large earthquakes, particularly alongthe Wasatch Front, since pioneer settlementin 1847. Most people living in Utah today havenot experienced a damaging earthquake inthe state. They are unaware of the long timeintervals between large earthquakes on faultsin the Basin and Range Province (average timebetween large earthquakes measured in hundredsto many thousands of years, comparedwith tens to hundreds of years for parts of theSan Andreas fault in California). Comparing theaverage recurrence interval with the amount oftime since the last large earthquake indicatesthat the next large earthquake is becoming increasinglylikely on certain parts of the Wasatchfault (see pages 6 and 7).1

WHY SHOULD I CARE?Utah and theIntermountain Westare Seismically ActiveGeologic evidence shows that movement onthe Wasatch fault and other faults in Utah cancause earthquakes of magnitude 6.5 to 7.5, withpotentially catastrophic effects. However, it canbe difficult to use this knowledge to make ussafer in our daily lives. Should we care only if welive along the Wasatch Front, or are other placesin Utah also dangerous?This section (pages 2-11) describes whereearthquakes occur in Utah and explains howearthquakes will shake the ground and causedamage in other ways, such as liquefaction andlandslides (pages 10 and 11). Technical termsused throughout this pamphlet are explainedin the Glossary (page 33).Stretching of the Crust Produces Movement on FaultsMost earthquakes occur on faults that form the boundariesof Earth’s tectonic plates. Utah is not on a plate boundary,but many faults in the state can produce large earthquakes.Between Utah’s Wasatch Range and California’s Sierra Nevada,tectonic forces within the western part of the North Americanplate combine with high heat flow from the underlying mantleto literally stretch the crust in an east-west direction at the rateof about one-half inch per year. In response to this stretching,the rigid crust breaks and shifts along faults, and the faultmovement produces earthquakes.Intermountain Seismic BeltUtah straddles the boundary between the extending Basinand Range Province to the west and the relatively more stableRocky Mountains and Colorado Plateau to the east. Thisboundary coincides with an area of earthquake activity calledthe Intermountain Seismic Belt (ISB; page 3). Utah’s longestand most active fault, the Wasatch fault, lies within the ISB.Unfortunately, the heavily populated Wasatch Front (Ogden –Salt Lake City – Provo urban corridor) and the rapidly growingSt. George and Cedar City areas are also within the ISB, puttingmost of Utah’s residents at risk.Sierra NevadaBasin and Range ProvinceWasatch RangeFault ScarpPACIFIC PLATENORTH AMERICAN PLATEWasatchFault(normal fault)CrustSan AndreasFault(strike-slip fault)UpwellingHeatMantleHorizontal extension creates normal faultsStretching, or horizontal extension, of the crust produces a type of dipping (or inclined) fault called a “normal” fault. The movement ofnormal faults is characterized by the crust above the fault plane moving down relative to the crust below the fault plane. This up/downmovement differs from movement on strike-slip faults like the San Andreas in California, where the crust on one side of the fault slideshorizontally past the crust on the other side. Earthquakes in Utah can be generated by movement on a variety of different types of faults,but the faults that are considered capable of generating large surface-faulting earthquakes are mainly normal faults in and near theedge of the Basin and Range Province in western and central Utah.For more information go to: Utah Geological Survey2

UTAH IS YOUR HOMEJuan de Fuca PlateRelative movement ofplate boundary faultNorth American PlateCANVWA1954M7.2ORSierra NevadaSierra NevadaID1915M7.61932M7.2Snake1983M7.3RiverBasinBasinandandPlainRangeRange1959M7.5ProvinceProvinceWasatch Range1934M6.6 OgdenSalt Lake CityProvoMTIntermountainSeismic BeltWASATCHFAULTUTAHWYRocky MountainsSt. GeorgeMoabColoradoColoradoAZPlateauPlateauNDCONMSAN ANDREAS FAULTSAN ANDREAS FAULT1934M6.6General direction of Basinand Range extensionArea of IntermountainSeismic Belt (ISB)Location, year, and magnitudeof large Basin and Range/ISBsurface-faulting earthquakesSource: Utah Geological SurveyFault scarp formationIn a large normal-faulting earthquake the amount of verticalmovement on the fault deep in Earth’s crust is sufficient torupture and offset the ground surface, producing a steep breakor scarp. Geologic evidence shows that individual prehistoricearthquakes on the Wasatch fault produced scarps 6 to 12 feethigh. Similar-sized scarps have formed during historical surfacefaultingearthquakes in the region, such as the scarp shownbelow, which formed during the 1983 magnitude 7.3 BorahPeak earthquake in Idaho(surface faulting has brokenand offset the concretelinedditch in which thepeople are standing). Overtime, repeated movementon a normal fault eventuallyproduces a mountain rangeon the uplifted crustal block(for example, the WasatchRange) and a valley or basinon the downdropped block(for example, Salt Lake Valley).(Photo courtesy of WalterArabasz)Surface faulting in UtahIn historical time, Utah has had only one earthquake largeenough to form a fault scarp. The 1934 magnitude 6.6 HanselValley earthquake was near the threshold magnitude forearthquakes that cause surface rupture, and produced a smallscarp in an unpopulated area north of Great Salt Lake. In SaltLake City, 80 miles away, ground shaking from this earthquakewas strong enough to cause adjacent 6- and 10-story buildingsto sway and batter against each other and clock equipment toshake loose from the City and County Building’s 12-story clocktower and crash down through the building. (Photo courtesyof the F.J. Pack Collection, Special Collections Department,University of Utah Libraries)3

WHY SHOULD I CARE?Most of Utah’sPopulated Area LiesWithin an ActiveEarthquake BeltEarthquakes in the Utah regionHistorical quakes ofabout magnitude (M) 5.5 andlarger in the Utah region*1884 M 6 Bear Lake Valley1887 M 5.5 Kanab1900 M 5.5 Eureka1901 M 6.5 Richfield1902 M 6 Pine Valley1909 M 6 Hansel Valley1910 M5.5 Salt Lake City1914 M 5.5 Ogden1921 M 6 Elsinore (two events)1934 M 6.6 Hansel Valley1959 M 5.7 Utah-Arizona Border1962 M 5.7 Richmond1966 M 6.0 Utah-Nevada Border1975 M 6.0 Utah-Idaho Border1992 M 5.9 St. George*sizes of shocks before 1934 are approximateMaking a home in Utah’searthquake belt…Distribution ofsettlementsin Utah in 1877Source: Atlas of Utah,Weber State College,1981What is UUSS?The University of Utah Seismograph Stations (UUSS)is a research, educational, and public-service entitythat operates a monitoring network of more than200 regional and urban seismic stations in Utahand neighboring areas, including the YellowstoneNational Park region. For more information aboutUUSS, recent earthquakes, and other earthquakeinformation, see

UTAH IS YOUR HOMEThreat 1 (time scale of hundreds to thousands of years):Infrequent, large surface-faulting earthquakes (M 6.5 to 7.5)on mapped active faults, such as the Wasatch fault.Threat 2 (time scale of tens of years):More frequent, moderate-size (M 5 to 6.5) earthquakes that donot cause surface faulting. If they occur under an urban area,as happened in the 1962 Magna earthquake (see photo below),considerable damage can result.Utah Faces a DualEarthquake Threat—and Earthquakesin Utah Are Not Just aWasatch Front ProblemEarthquakes occur throughout Utah• More than 36,000 earthquakes haveoccurred in the Utah region since1962. The Wasatch Front is part of aregional Intermountain Seismic Belt(map on page 3).• One-half of the 16 damaging earthquakesin Utah of magnitude 5.5and larger since 1850 have occurredoutside the Wasatch Front area incentral and southwestern Utah.Large photo: Damage in SaltLake City caused by the M 5.2Magna earthquake of 1962.(Photo courtesy of DeseretNews, Salt Lake City, Utah)Smaller photos: Damage caused by the M 5.7 Richmond (CacheValley) earthquake of 1962 (top) and the M 6 Elsinore, Utah,earthquakes of 1921 (bottom). (Photos courtesy of, respectively, ArielD. Benson, Richmond, Utah, and the F. J. Pack Collection, SpecialCollections Department, University of Utah Libraries)• One of the largest historical earthquakesin Utah was a damagingshock of magnitude 6.5 near Richfieldin 1901. The Sevier Valley areabetween Richfield and Marysvale hashad eight earthquakes of magnitude5 and larger.• Thousands of mining-induced earthquakes(as large as magnitude 4.2),caused by underground coal mining,have occurred in Carbon, Emery, andeastern Sevier Counties.• In the Uinta Basin, an earthquakeof magnitude 4.5 in 1977 causedminor damage north of Duchesne.Earthquakes as large as magnitude4.9 have been induced by oil and gasproduction and other activities in theColorado-Utah border region.5

WHY SHOULD I CARE?The Wasatch FaultOne of the longest and most active normal faults in theworld, the 240-mile-long Wasatch fault extends fromMalad City, Idaho, south to Fayette, Utah. The fault issubdivided into 10 segments, averaging 25 miles inlength; each segment is generally thought to ruptureindependently and is a separate source of large earthquakes.Although scientists are unsure about how many smalltomoderate-size historical earthquakes can be attributedto slip on the Wasatch fault at depth, the geologicrecord shows that numerous large (magnitude 6.5-7.5)surface-faulting earthquakes have taken place on theWasatch fault over the past 10,000 years.AA: The Wasatch fault (white arrows) typically extends along the baseof the Wasatch Range, as seen in this view to the east near Mapletonin Utah County. (Photo courtesy of Rod Millar)BB: In some areas, the Wasatch fault (white arrows) trends away from themountain front, as seen here in this view to the northeast in Salt LakeValley along Highland Drive near 3900 South. (Photo courtesy of RodMillar)Map showing the Wasatch fault (red line) and other faults (black lines)in Utah that may be the sources of large earthquakes. Source: UtahGeological Survey6CC: At the mouth of Little Cottonwood Canyon in Salt Lake Valley, theG.K. Gilbert Geologic View Park (yellow arrow) is along the Wasatchfault (white arrows). (Photo courtesy of UGS)

UTAH IS YOUR HOMEGeologic information for Wasatch fault earthquakes comeslargely from trenches excavated across fault scarps. Twentyfiveresearch sites, many of which had more than onetrench, have been investigated on the Wasatch fault. Thesetrench studies provide information on the timing and size ofprehistoric surface-faulting earthquakes.Radiocarbon dating of organic debris found in this trench(excavated in spring 2007) across the northern Webersegment indicates the timing of recent large earthquakes.During each of these earthquakes, the ground surface wasdisplaced vertically about 10 feet. (Photo courtesy of UGS)At least 23 large (magnitude ~7) surface-faulting earthquakes haveoccurred on the central segments of the Wasatch fault zone in the past6500 years, which is an average of an earthquake every 300 years. Themost recent large earthquake on the Wasatch fault took place about 300years ago on the Nephi segment. In the Salt Lake City area, the Wasatchfault (Salt Lake City segment) has an average recurrence time betweenlarge earthquakes of about 1300 years; however, the last major earthquakeoccurred about 1400 years ago. Enough energy has accumulated on theSalt Lake City segment to produce a magnitude 7.0 earthquake.Source: Utah Geological Survey7

WHY SHOULD I CARE?Most EarthquakeDamage is Causedby ShakingU.S. Geological Survey National Seismic Hazard Map of Utah• On this map, the strongest shaking based on long-term forecasts is generallyexpected near major faults, such as the Wasatch fault, and in areas of greatesthistorical seismicity such as the Intermountain Seismic Belt.• Intense shaking can damage even strong modern buildings and theircontents.• Much of Utah has a moderate to high likelihood of future intense shaking.The intensity of shaking that abuilding or structure will experienceduring an earthquake is highlyvariable, but generally depends onthree main factors:• The magnitude of the earthquake—in general, the larger the quake, thestronger the shaking and the largerthe area affected.• The distance from the earthquake—the closer to the source of the earthquake,the greater the shaking.• The type of ground material beneaththe structure—soils may amplify ordeamplify the shaking relative to hardbedrock.Compiled by Utah Geological Survey from: USGS National Seismic Hazard Maps.AMPLIFICATION OF EARTHQUAKE SHAKINGSite effect: 1Simulatedseismograph response:Consolidated soil& bedrockFAULTRUPTUREJordanRiverSevere shakingModerate-heavy damageEARTHQUAKEEPICENTERSALT LAKE CITYThick, soft soilSeismic waves2Violent shakingHeavy damageWASATCHFAULT1233Strong shakingLight-moderate damageThin, stiff soilWASATCHRANGEBedrockAmplified low-frequency groundmotions (tall buildings affected)Amplified high-frequency groundmotions (short buildings affected)near Wasatch faultBedrock does not amplify orprolong ground motionsGeneralized east-west cross section throughthe eastern part of Salt Lake Valley, showing theresponse to seismic waves generated during aWasatch fault earthquake. Earthquakes generateseismic waves at a wide variety of frequencies, andcertain frequency waves may be amplified by localsoil conditions.• In Salt Lake Valley, areas with thick, soft, clayey soilamplify low-frequency seismic waves, yieldingslow rolling-type shaking that can damage tallbuildings and long-span overpasses.• Areas with thin, stiff (e.g., sandy and gravelly) soilover bedrock amplify high-frequency seismicwaves, which yield vigorous ground vibrationsthat cause more damage to short (1-2 story)buildings, such as houses.8Source: Utah Geological Survey

UTAH IS YOUR HOMEStrong ground shaking from a magnitude 7 or greaterearthquake along one of the segments of the Wasatch fault(see map, page 7) will cause major losses. However, we donot need to wait for these earthquakes to occur to estimatewhat they could do to Wasatch Front communities. Usingthe Federal Emergency Management Agency’s Hazards U.S.loss-estimation model, we can estimate the extent of futuredamage and take actions now to reduce potential lossesand plan for recovery.Wasatch fault segmentBuildinglosses($ billions)DisplacedhouseholdsLife-threateninginjuriesand fatalitiesBrigham City 3 14,000 500Weber 16 57,000 3,000Salt Lake City 42 150,000 9,000Provo 14 48,000 3,000Nephi 1 4,000 200Losses estimated for a magnitude 7 earthquake on each of the centralsegments of the Wasatch fault (page 7)Bountiful0 10Geologic site conditions affect ground shaking• This map shows the distribution of different soiltypes in Salt Lake Valley.• The intensity of shaking is influenced by the type ofmaterials underlying an area.• Deep sediment-filled basins and soft soils suchas wet clay amplify and prolong low-frequencyshaking; shallow, stiff soils amplify high-frequencyshaking.Magnitude or Intensity?Magnitude is a measure of the energy releasedin an earthquake—a single value that dependson the area of fault rupture and amount of slip.For example, the 1934 Hansel Valley earthquakehad a magnitude of 6.6. The largest expectedearthquakes in Utah are magnitude 7.0-7.5.NSalt Lake CitySouth Salt LakeWest Valley CityTaylorsvilleHolladayMurrayCottonwood HeightsWest JordanMidvaleSouth JordanRivertonDraperIntensity is a measure of the strength of groundshaking at a particular place, and varies by location,proximity to the source of the earthquake, andtype of material underlying the site. The intensityscale ranges from low (I) to high (XII). Near theepicenter of the Hansel Valley earthquake, theintensity reached VIII; however, in Salt Lake City,intensity levels were about VI.0.0 0.3 0.6PGAPeak groundacceleration(PGA):0.60 gViolent shaking,Heavy damageMap showing levels of strong ground shaking expected in Salt Lake Valley basedon six ground motion simulations for a magnitude 7.0 earthquake on the SaltLake City segment of the Wasatch fault.9

WHY SHOULD I CARE?Earthquakes AlsoCause Damage inOther WaysAlthough most earthquake damage is causedby shaking, other damaging effects of quakescan be just as devastating. For example, in the1992 magnitude 5.9 St. George earthquake, thegreatest damage to houses was caused by amassive landslide in Springdale.Damaged infrastructureEarthquakes often damage roads andbridges, hindering rescue and recoveryefforts and causing accidents. Waterand sewer pipeline breaks can result incontamination of surface and groundwater, and cause “sinkholes” that undermineroads and buildings. Damage tonatural gas and electrical distributionsystems can cause fires and majorservice outages. Damage to petroleumpipelines can cause oil spills. The photobelow shows damage to a Santa Monicafreeway bridge in Los Angeles in the 1994magnitude 6.7 Northridge earthquake.This bridge was similar in construction toolder bridges along Utah freeways.(Los Angeles Times photo by Lacy Atkins )FiresEarthquakes in urban areas are oftenfollowed by destructive fires because gaslines break, electrical shorts ignite fires,damaged water tanks and broken pipeslimit water for firefighting, and cloggedroads and collapsed bridges preventaccess for firefighters. The photo aboveis an aerial view of Balboa Boulevard inGranada Hills in the 1994 Northridgeearthquake showing street flooding,flames due to a broken natural gas line,and burned homes.(Los Angeles Times photo by Gail Fisher )Dam failures and seichesEarthquakes can make dams fail andgenerate waves (seiches) many feet highthat flood shorelines and wash overdams. Hebgen Lake Dam, shown below,was damaged by ground shaking, andwas also overtopped numerous times aswaves sloshed back and forth in HebgenLake following the 1959 magnitude 7.5earthquake in Montana.(Photo from U.S. Forest ServiceMiscellaneous Publication 907)Surface fault ruptureIn a large earthquake, fault movementcan break the ground surface, damagingbuildings and other structures. In Utah,the Wasatch fault extends the entirelength of the Wasatch Front throughmany urban neighborhoods. NearHebgen Lake in Montana, the barnshown below was damaged when theRed Canyon fault moved in the 1959Hebgen Lake earthquake.Hazardous materialsEarthquake damage can cause releasesof hazardous materials from refineriesand other chemical storage and distributionsystems, research and industriallaboratories, manufacturing plants, andrailroad tank cars. The photo aboveshows a train derailment in the 1994Northridge earthquake that releasedsulfuric acid from a tanker car.(Photo courtesy of UGS)(Photo from U.S. Forest ServiceMiscellaneous Publication 907)10

UTAH IS YOUR HOMETectonic subsidenceSurface faulting on normal faults causessubsidence and tilting on the downdroppedside of the fault. The photobelow shows abandonment of the southshore of Hebgen Lake in the 1959 earthquakeas the lake bed tilted to the northtoward the fault. Flooding may occuralong the east shores of Great Salt Lakeand Utah Lake due to subsidence fromearthquakes on the Wasatch fault.(Photo courtesy of Terry A. Humphrey, U.S.Bureau of Land Management)LandslidesEarthquakes can trigger landslides thatdamage roads, buildings, pipelines, andother infrastructure. In Springdale, thehome shown below was destroyed whena hillside gave way in the 1992 magnitude5.9 St. George earthquake 27 milesto the west.(Photo from U.S. Forest ServiceMiscellaneous Publication 907)Rock fallOne of the most common types oflandslides caused by earthquakes arerock falls, triggered by ground shakingin areas of rock outcrops or loose rockson hillsides. The photo above showsdust clouds created by numerousrock falls along cliffs near Price in the1988 magnitude 5.3 San Rafael Swellearthquake.(Photo courtesy of UGS)LiquefactionEarthquake shaking can cause certainsoils to behave like a liquid and lose theirability to support structures. Liquefactionoften causes buried gas and water linesto break. The highest potential for liquefactionis in low-lying areas in saturated,loose, sandy soils and poorly compactedartificial fill. Geologic evidence in Utahindicates that severe ground deformationcaused by liquefaction has occurredduring large prehistoric earthquakes. Thephoto below shows liquefaction-relateddamage to a road at Moss Landing StateBeach on Monterey Bay following the1989 magnitude 6.9 Loma Prieta, California,earthquake.Source: Salt Lake County Planning andMap Showing Potential Seismic Hazard Areas Development ServicesThis map of northeastern Salt Lake Valley shows areas where a surface-faulting or liquefactionhazard may exist and where site-specific studies addressing the hazards are recommended prior todevelopment. Such special-study-area maps are available at most Wasatch Front county planningdepartments, and many cities have adopted them in their subdivision-approval process.(Photo by Dan Orange, University ofCalifornia at Santa Cruz)11

WHY SHOULD I PREPARE?Response of Buildingsto EarthquakesMuch like an automobile on a winding roadway, buildingssway to the effects of earthquakes. Foundations connectstructures to the ground, and they play a very important rolein determining how much force a building can resist. Engineersstudy this critical interface and may choose to “cushion”the effect by using special foundation designs.The soil underlying buildings is an important ingredient indetermining the effects of earthquakes on structures.• Soft, clayey soils tend to increase the motion at the groundsurface and thereby amplify the effects on buildings andstructures.• Rock doesn’t change the motion nearly as much as soil, soshaking is more predictable.A building’s configuration and height also play an importantrole in determining the effects an earthquake will have on itsperformance.• Square or rectangular buildings typically perform better thanirregular-shaped buildings.• Tall buildings respond by swaying back and forth.• Short structures are jarred from side to side as the earthquakereleases its force at the ground surface.The materials from which a building is constructed helpdetermine how it performs during an earthquake.• Steel and wood are considered flexible or “ductile” and tend toabsorb the energy.• Concrete and masonry are more “rigid” and can transfer the groundmotion directly into the structure.Earthquakes shake buildings from the ground up, and animportant consideration for performance is the length oftime the ground shakes. The longer the ground shakes, themore likely the structure will be unable to resist the effects.Building materials can resist temporary “overstress,” butwhen stretched beyond their limits, will break, much like apaper clip bent back and forth will eventually break.A building’s “skeleton” or structure is most important for protectingthe lives and safety of its occupants. But so-called “nonstructural”elements such as bookcases, shelves, ceiling tiles, and light fixturesoften fall to the floor or hurtle across rooms during earthquakes,injuring and possibly killing occupants. Such problems can be anticipatedand addressed before an earthquake. Just as buildings shouldbe designed and braced for earthquakes, nonstructural componentsrequire similar consideration.Unreinforced Masonry BuildingsOne building type of particular concern in Utah is masonry constructedwithout steel reinforcement. Unreinforced masonrybuildings were popular when the state was first settled andcontinued to be built into the 1970s.Bricks are created from clay which is burned in ovens at hightemperatures. This material was both readily available hereand familiar to the early settlers.Many residences, in addition to commercial buildings, areunreinforced masonry buildings and were constructed withoutknowledge of how these structures performed in earthquakes.Unfortunately, experience now shows this is one of the mostdangerous building types and evidence of its poor performancein earthquakes throughout the world is well documented.In addition to buildings, virtually all structures are susceptible todamage from an earthquake. Dams, bridges, pipelines, storagetanks, and roadways are other structures that can be damaged by anearthquake’s forces.These infrastructure elements are often taken for granted and onlyafter an earthquake are they viewed as critical components, necessaryfor maintaining our standard of living. The infrastructure we relyupon can be fragile in ways we may not understand until after it isdamaged or disabled in an earthquake.(Photo courtesy of Utah Office ofTourism; Frank Jensen)12

BIG QUAKES WILL AFFECT YOUThe ABCs of SeismicBuilding CodesSeismic building codes increase building integrity and help ensurethe future safety of communities. These codes are designed toprotect lives, but not to ensure buildings are undamaged or usableafter an earthquake. Seismic codes are intended to protect peopleinside buildings by preventing collapse and allowing safe evacuation.Structures built according to the current code should resist minorearthquakes undamaged, resist moderate earthquakes withoutsignificant structural damage, and resist severe earthquakes withoutcollapse.A moderate earthquake that does not significantly damage a buildingstill can seriously hurt or kill people. Buildings contain items such aslight fixtures, heating ducts, windows, and suspended ceilings thatcan fall on people or block escape routes. The exteriors of buildingsalso can pose hazards to people walking by or exiting, includingfalling bricks, parapets, window glass, or other facades.Damage to Interstate 5 in 1994 Northridge, California,earthquake. (Photo courtesy of FEMA)Steel-frame tall buildings andnewer wood-frame short buildingsare usually (but not always) thesafest structure types. Exceptionsto these generalizations are due to variables such as the configurationof the building, the quality of construction and inspection, the designof connections, and the manner in which seismic waves strike aparticular site.Building codes provide minimum design and constructionrequirements for protecting lives. However, some structureswith high occupancy, critical-response services (fire, police,hospitals), and vulnerable populations (schools, nursing homes)should be built above minimum requirements. Building codesuse importance factors for designing above these minimumrequirements. It also is important to protect utilities and infrastructuresince damage to these critical structures leads to more deaths, largereconomic loss, greater social disruption, and slower response toearthquakes.The seismic provisions of building codes arebased on earthquake hazard maps (example atright) which show the probabilities of certainlevels of earthquake shaking in particular areas.The code requirements reflect the fact thatsome places are more likely than others to havestrong earthquakes. Utah has areas with a highlikelihood of strong earthquakes, similar tostates along the West Coast.Map showing the ground-shaking hazard in the United States.In Utah, seismic codes made substantialimprovements in construction as early as themid-1970s. Buildings constructed prior tothis time may be seismically unsafe. However,buildings constructed in the 1980s wouldalso not be as seismically safe as buildingsconstructed under today’s seismic codes. Tokeep up with the current state of the art inseismic design, building codes are revised everythree years to incorporate new knowledge.Source: USGS National Seismic Hazard Maps13

WHY SHOULD I PREPARE?Utah’s People, Economy, and Infrastructure areIncreasingly Vulnerable to a Wasatch Fault Earthquake• Nearly 80 percent of Utah’s populationlives within 15 miles of the Wasatch faultin the Wasatch Front area.• More than 75 percent of Utah’s economy isconcentrated in Salt Lake, Utah, Davis, andWeber counties—above the Wasatch fault,which projects beneath the developedWasatch Front valleys.• Most of Utah’s state government facilitiesare located within 15 miles of the Wasatchfault.• Major interstate transportation corridorsand the Salt Lake City International Airportare located within 15 miles of the Wasatchfault.• By 2030 the population in the WasatchFront area is projected to grow to 2.8million, a 50 percent increase over 2005.• To meet the needs of the dramaticallygrowing population along the WasatchFront, $14.4 billion of new transit andhighway infrastructure is planned over thenext three decades .Earthquake risk (theprobability of loss ordamage) is increasingwith population growthand development.The Scenario ShakeMap (left) shows the predicted levels of groundshaking during a magnitude 7.0 earthquake on the Salt Lake Citysegment of the Wasatch fault (see page 32 to learn more aboutShakeMaps). Severe shaking capable of causing moderate to heavydamage will extend beyond Salt Lake Valley—both northward intoDavis County and southward into Utah County.Compare the ShakeMap (left) with the map of developed landin the Wasatch Front area (above). Much of the Wasatch Front’spopulation and an extensive part of its built environment willexperience strong to severe shaking when the Wasatch faultunleashes a “Big One” in Salt Lake Valley.14

BIG QUAKES WILL AFFECT YOUHow Likely is a “Big One*”?Earthquake SourceSalt Lake City segment of theWasatch faultOne of the Wasatch fault’s fivecentral segments (Brigham Cityto Nephi, page 7)One of 30 active faults in theWasatch Front region (page 6)AnnualLikelihood1 in 450to 1 in 1,6001 in 300to 1 in 4001 in 200* A large surface-faulting earthquake of about magnitude 7Illustration by Pat Bagley, The Salt Lake Tribune.Average Frequency of Earthquakes* in the...Wasatch FrontEntire Utah Region(see map, page 4)Magnitude Frequency Frequency≥ 3.0 3 per year 8 per year≥ 4.0 1 every 2 years 1 per year≥ 5.0 1 every 10 years 1 every 5 years≥ 5.5 1 every 20 years 1 every 10 years≥ 6.0 1 every 50 years 1 every 30 years[based on geologic evidence, time scale of≥ 7.0hundreds of years - page 7]≥ Greater than or equal to* Based on historical record and instrumental monitoring (largest historical shockwas M 6.6 in 1934); excludes foreshocks, aftershocks, and human-triggered seismiceventsSource: University of Utah Seismograph StationsSources: Likelihood calculated by the University of UtahSeismograph Stations from data provided in UGS, USGS,GeoHaz Consultants, and URS Corporation reports.Reality Check(for comparing to the chance of a “Big One”)Cause of DeathYour Annual RiskHeart disease 1 in 450Cancer 1 in 530Stroke 1 in 2,100Motor-vehicle accident 1 in 6,500Source: Centers for Disease Control and Prevention; causes ofdeath in the U.S. in 2005.Don’t be fooled!—Myth number 2“UTAH ISN’T CALIFORNIA”True, Utah is not California. However, many earthquakes are recorded andlocated each year in the Utah region (page 4)—about 800 per year onaverage, excluding mining seismicity. Most of these earthquakes are smalland not felt. Since 1850, 16 damaging shocks of about magnitude 5.5 andlarger have occurred in the Utah region. California certainly has more“wake-up calls,” where earthquakes of about magnitude 6.5 and largerthat cause fatalities and major structural damage typically occur once ortwice per decade.Scientific studies in Utah indicate that “Big Ones” occur somewhere inthe Wasatch Front area on a time scale of every few hundreds of years.These are high-energy earthquakes of about magnitude 7. They suddenlydisplace the ground vertically about 10 feet at the fault line. Within tens ofmiles of the epicenter there is a high potential for major structural damageand casualties. In Utah, many seismically vulnerable buildings increasethe damage potential. On a geologic time table, Utah is due for its next“Big One”—and, unfortunately, is a lot like California in this regard.15

WHY SHOULD I PREPARE?Your Life Could Change Unexpectedly in the Next QuakeWhere will your family be?• Your children may be at school,day care, or other activities.• Family members may be at workor commuting.• Pets may run away or be injured.Failure of fluorescent light fixtures inthe Dawson Elementary School Libraryduring the 1983 Coalinga, California,earthquake. (Earthquake EngineeringResearch Institute photo)Pets are not allowed in most emergencyshelters. Do you have a plan to feed andcare for your animals after an earthquake?Will you have medical services?Will you be able to get home?• The 911 emergency system willlikely be overloaded.• Hospitals and other medicalfacilities may be damaged.• Emergency rooms and traumacenters may be overwhelmed.• Assisted living, critical care, andother health services such asdialysis may not be operational.This hospital inSylmar, California, hadto be demolished afterthe 1971 magnitude6.7 San Fernandoearthquake. (Photocourtesy of USGS)• Road damage andclosures may restrict yourability to travel by car.• Public transportation,including buses, TRAX,trains, and airports mayexperience closures orinterruptions in service.• Commute times may bedramatically increased.The 1989 magnitude 6.9 LomaPrieta earthquake caused thissection of the San Francisco-Oakland Bay Bridge to collapse.(Photo courtesy of USGS)16

BIG QUAKES WILL AFFECT YOUWill you be able to stayin your home?This porch on a wood-frame housefailed during the 1989 magnitude6.9 Loma Prieta earthquake. The“red tag” indicates that this home isunsafe and must not be entered oroccupied. (Photo courtesy of USGS)• Your home may be damaged andunsafe to live in.• Your personal property may bedamaged or destroyed.• Construction materials and labor forrepairs will be in limited supply andcosts will increase.• Rebuilding scams may be common.• Availability of rental housing maybe limited due to damage and highdemand.Where will you get yourwater, food, medicines,and gasoline after anearthquake? (Photocourtesy of USGS)Can you live without theservices you rely on?• Water may be in short supply.• Natural gas and electric power may be out for daysor weeks.• Garbage and sewage services may be interrupted.• Telephone, Internet, cell phone, and wirelesscommunications may be overloaded or unavailable.• Mail service may be disrupted or delayed.• Gasoline may be in short supply, and rationing maybe necessary.• Bank operations may be disrupted, limiting access tocash, ATMs, or online banking.• Grocery, drug, and other retail stores may be closedor unable to restock shelves.How will your job be affected?• Businesses may sustain damage anddisruption—many small businesses requirea long time to reopen or do not survivedisasters.• Your income may be affected—payroll checksor direct deposits may be delayed.• Your workplace may become a temporaryshelter for you or others.• Supplies and deliveries will be interrupted.How will the AmericanRed Cross Help?After a damaging earthquake,the American Red Cross willhelp in the following ways:• Opening and operatingemergency shelters.• Providing food at sheltersand feeding locationsand through mobiledistribution.• Obtaining and deliveringother needed items such aswater, baby supplies, andblankets.• Assisting with theimmediate mental-healthneeds of those affected.• Providing for basic healthneeds at shelters and otherlocations.• Helping with initialrecovery through caseworkand referrals to otheragencies and partners.• Providing blood and bloodproducts.For more information go to:www.utahredcross.orgThis business in Santa Cruz, California, was nearlydestroyed in the 1989 magnitude 6.9 Loma Prietaearthquake. (Photo courtesy of USGS)17

WHY SHOULD I PREPARE?Your Financial Situation CouldBe Affected by a QuakeAid may not be available immediately following a majordisaster. Without proper planning, the financial impact ofan earthquake on you and your family could be devastating.Although many things are out of your control after a quake,your ability to recover financially depends on a number offactors that you can control. Prepare and follow a financialdisaster recovery plan and you will be more likely to recoversuccessfully. Consider the following:This store wastemporarily closedfollowing the2001 magnitude6.8 Nisqually,Washington,earthquake. (Photocourtesy of TheOlympian, Olympia,Wash.)Will you have money, food, and medicine?• Bank operations may be disrupted, limiting access to cash, ATMs,or online banking.• Food, drug, and other retail stores where you shop may be closedor unable to restock shelves.This bank wasdamaged inthe NisquallyWashington,earthquake,requiring customersto seek serviceselsewhere. (Photocourtesy of TheOlympian, Olympia,Wash.)Will you be able to recover financially?• You are still responsible for your existing debts, such as mortgage,lease, car, and credit-card payments.• You may not have access to important financial records.• Your assets are at risk without sufficient earthquake insurance.• If you have earthquake insurance and experience loss, beginworking with your insurer to file a claim as quickly as possible.Will your insurance cover your losses?• Homeowner’s and renter’s insurance policies do not cover lossesrelated to earthquakes.• A separate earthquake insurance policy is one way to help protectyour home, in addition to seismic retrofitting.• Earthquake insurance also helps with additional living expensesin the days and weeks after earthquakes.• Relatively few Utah homeowners have earthquake insurance.Don’t be fooled!—Myth number 3“HOMEOWNER’S INSURANCE WILL COVER ANY DAMAGE TO MYHOME OR BELONGINGS CAUSED BY AN EARTHQUAKE.”Most residential property insurancepolicies do not coverdamage resulting from earthquakes.A separate earthquakeinsurance policy is one way toprotect your home and the investmentsyou have made inpersonal belongings. Investigateyour options carefully toensure that your assets are sufficientlyprotected.18

BIG QUAKES WILL AFFECT YOUDoes your small business have a recovery plan?• A business disaster-recovery plan will make your business betterable to survive in a post-disaster environment.• Although physical assets can be replaced, emotional and socialchanges that affect businesses and their customers may remainlong after a disaster.• Businesses may not return to their previous revenue levels aftera disaster; however, some businesses such as construction arelikely to be in great demand following an earthquake.These small businesses in Santa Cruz, California, wereheavily damaged in the 1989 magnitude 6.9 LomaPrieta earthquake, but both eventually reopened. (Photocourtesy of USGS)What types of federal assistance may beavailable?• Federal disaster-relief programs are designed to help you getpartly back on your feet but not to replace everything you lose.• The Department of Homeland Security’s Federal EmergencyManagement Agency (FEMA) is responsible for responding to,planning for, and reducing the effects of disasters.• After the president signs a major disaster declaration, FEMAcooperates with other agencies, such as the Small BusinessAdministration (SBA), in providing disaster relief.• For disaster relief, low-interest loans are made available throughthe SBA to eligible individuals, homeowners, and businesses torepair or replace damaged property and personal belongingsnot covered by insurance.• The maximum SBA personal-property loan is $40,000, and themaximum SBA real-property loan for primary home repair is$200,000.• FEMA disaster grants for emergency home repairs and temporaryrental assistance are available to individuals and households.• The average FEMA grant is less than $15,000 (the maximum is$28,800)—not enough to rebuild a home.• The Farm Service Agency offers loans to assist agricultural businesses.This home in the Santa Cruz Mountains collapsed in theLoma Prieta earthquake. (Photo courtesy of USGS)Useful Web sitesReady Your Business: Disaster Planning:http://utah.acp-international.comBusiness Preparedness Information:

WHAT SHOULD I DO?The Seven Steps to Earthquake SafetyEarthquakes in Utah are inevitable, but damage from themcan be reduced. Steps you can take before, during, and afterearthquakes will help make you and your family safer andreduce your injuries, damage, and losses:• First and foremost, plan for the personal safety of you andyour loved ones.• Look into the safety of your home, workplace, and child’sschool—don’t be afraid to ask your landlord, boss, orschool’s principal if they are aware of the hazards andhave taken measures to make these places safer andmore earthquake resistant.• Find out if your home, workplace, and child’s schoolcould be subjected to seismic hazards such as landslidingor liquefaction, in addition to strong shaking.• Don’t forget to think about likely economic impacts toyou and your family from a major quake (see pages 18,19, and 31).The seven steps described in this section will help you tobe safer in earthquakes. They are arranged as measures youshould take before, during, and after quakes. In addition tofollowing the steps at home, they should also be followedat schools and workplaces. If everyone makes an effortto follow these steps, billions of dollars could be saved,injuries avoided, and many deaths averted in the next bigearthquake.You’ve learned your earthquake hazards, now follow these seven steps:BEFORE A QUAKE: STEP 1. Identify potential hazards in your home and begin to fix them(page 22).STEP 2. Create a disaster-preparedness plan (page 24).STEP 3. Prepare disaster supply kits (page 25).STEP 4. Identify your building’s potential weaknesses and begin to fixthem (page 26).DURING A QUAKE:STEP 5. Protect yourself during earthquake shaking (page 28).AFTER A QUAKE:STEP 6. After the earthquake, check for injuries and damage (page 29).STEP 7. When safe, continue to follow your disaster-preparedness plan(page 30).20

FOLLOW THE SEVEN STEPS TO EARTHQUAKE SAFETYWhen safe, continue to follow yourdisaster-preparedness plan. (page 30)After the earthquake, check forinjuries and damage. (page 29) page 295Protect yourself during earthquakeshaking–DROP, COVER AND HOLD ON.(page 28) page 28Identify your building’s potentialweaknesses and begin to fix them.(page 26)Prepare disaster supply kits.(page 25)Create a disaster-preparedness plan.(page 24)Identify potential hazards in yourhome and begin to fix them.(page 22)21

WHAT SHOULD I DO?STEP 1Identify Potential Hazards in YourHome and Begin to Fix ThemThe first step to earthquake safety is to lookaround your home and identify all unsecuredobjects that might fall during shaking.START NOW by moving heavy furniture, such asbookcases, away from beds, couches, and otherplaces where people sit or sleep. Also make surethat exit paths are clear of clutter.Simple and inexpensive things that you cando now will help reduce injuries and protectbelongings in a quake. Most hardware andhome-improvement stores carry earthquakesafetystraps, fasteners, and adhesives that youcan easily use to secure your belongings.The following tips describe simple solutions tosituations in your home that could be dangerousduring earthquake shaking. If these have not yetbeen done in your home, take action now:ooCheck the boxes!Don’t be fooled!—Myth number 4“QUAKE INJURIES ARE ALL FROM COLLAPSINGBUILDINGS.”Many people think that all injuries in earthquakes arecaused by collapsing buildings. Actually, most injuriesin quakes are from objects that break or fall on people.For example, in the 1994 magnitude 6.7 Northridgeearthquake, 55 percent of quake-relatedinjuries were caused by fallingobjects, such as televisions,pictures and mirrors,and heavy lightfixtures.Hanging objectsArt and other heavy objects hungon walls may fall, and glass inpictures and mirrors may shatter.ooPlace only soft art, such asunframed posters or rugsand tapestries, above beds orsofas.ooHang mirrors, pictures, andother hanging objects onclosed hooks.Objects on open shelves and tabletopsCollectibles and other looseobjects can become dangerousprojectiles.ooHold collectibles, pottery,and lamps in place by usingremovable earthquake putty,museum wax, or quake gel.FurnitureTall, top-heavy furniture, such asbookcases and entertainmentcenters, may fall and injure you.ooStore heavy items andbreakables on lower shelves.ooSecure both top corners of tallfurniture into a wall stud, notjust to the drywall.ooFlexible-mount fasteners, suchas nylon straps, allow furnitureindependent movement fromthe wall, reducing strain onstuds.22

FOLLOW THE SEVEN STEPS TO EARTHQUAKE SAFETYWater and gas pipesWater or gas pipes anywhere in your home can break. Waterleaks can cause extensive damage, and gas leaks are a majorfire hazard.ooHave a plumber evaluate, replace, and properly securerusted or worn water and gas pipes.ooIf not already done, have a plumber replace rigid gasconnections to water heaters, stoves, dryers, and othergas appliances with flexible (corrugated) stainless-steelgas connectors (see below).ooExcess-flow gas-shutoff valves for individual appliances,which stop gas flow in case of a catastrophic leak, arealso now available for use with flexible connectors.Water heatersUnsecured water heaters may fall over, rupturing rigid waterand gas connections.ooWater heaters should be anchored to wall studs ormasonry with metal straps and lagscrews. Kits are available athardware stores and homecenters.ooIf not alreadydone, havea plumberinstall flexible(corrugated)copper waterconnectors.FlexiblewaterconnectorsIn the kitchenGlassware and china may crash to the floor ifcabinet doors are unsecured. Gas appliancescan shift, rupturing their gas connections.ooSecure all cabinet doors,especially those overhead, tohelp prevent contents fromfalling out during quakes.Use latches designedfor child-proofing orearthquake or boatsafety.ooSecure refrigeratorsand other majorappliances to wallsusing earthquakeappliance straps.In the garage or utility roomItems stored in garages and utility rooms can fall, causinginjuries, damage, and hazardous spills or leaks.ooMove flammable or hazardous materials to low areas thatare secure.ooEnsure that items stored above or beside vehicles cannotfall, damaging or blocking them.Home electronicsLarge electronic devices may fall, causing injuries anddamage. They are also costly to replace.ooSecure TVs, stereos, computers, and microwave ovenswith flexible nylon straps and buckles for easy removaland relocation.Flexiblegas connectorFor more information on making yourhome safer in earthquakes go to:http://beready.utah.govBEFORE A QUAKE23

WHAT SHOULD I DO?STEP 2Create a Disaster-Preparedness PlanWill everyone in your household know how to react during andafter strong earthquake shaking? To be ready for the quakesthat are certain to happen in Utah, it is important that yourfamily have a disaster-preparedness plan. Hold occasionalearthquake “drills” to practice your plan. Share your disasterplan with your neighbors and discuss key points with babysitters,house sitters, and house guests. Your plan should includemost of the following:Plan NOW to be safe during an earthquakeIn a strong earthquake, individual survival skills willbe crucial:ooPractice "DROP, COVER, AND HOLD ON." (See STEP 5, page28)ooIdentify safe spots in every room, such as under sturdydesks and tables.ooLearn how to protect yourself no matter where you arewhen an earthquake strikes. (See STEP 5, page 28)Plan NOW to respond after an earthquakeDoing the following will enable you to help yourfamily and others after a strong quake:ooKeep shoes and a working flashlight next to each bed.ooTeach everyone in your household to use emergencywhistles and (or) to knock three times repeatedly iftrapped. Rescuers searching collapsed buildings will belistening for sounds.ooIdentify the needs of household members and neighborswith special requirements or situations, such as use of awheelchair, walking aids, special diets, or medication.ooTake a Red Cross first aid and CPR (cardiopulmonaryresuscitation) training course. Learn who in yourneighborhood is trained in first aid and CPR.ooKnow the locations of utility shutoffs and keep neededtools nearby. Know how to turn off the gas, water, andelectricity to your home. Only turn off the gas if you smellor hear leaking gas. (See STEP 6, page 29)ooGet training from your local fire department in how toproperly use a fire extinguisher.ooInstall smoke alarms and test them monthly. Changethe battery once a year, or sooner if the alarm emits a"chirping" sound (low-battery signal).ooCheck with your fire department to see if there is aCommunity Emergency Response Team (CERT) in yourarea. If not, ask how to start one.Plan NOW to communicate and recover after anearthquakeDon’t wait until the next earthquake to do the following:ooLocate a safe place outside of your home for your familyto meet after the shaking stops.ooEstablish an out-of-area contact person who can be calledby everyone in the household to relay information.ooProvide all family members with a list of importantcontact phone numbers.ooDetermine where you might live if your home cannotbe occupied after an earthquake or other disaster (askfriends or relatives).ooLearn about the earthquake plan developed by yourchildren’s school or day care, and keep your children'sschool emergency release cards current.ooKeep copies of insurance policies, financial records, andother essential documents in a secure location, such aswith your household disaster kit. Include a householdinventory (a list and photos or video of your belongings).Your family may besleeping when the nextstrong quake hits Utah.After the shaking stops,the lights may be out andbroken glass and otherdangerous debris maylitter the floor, making itunsafe to walk barefoot.Keep a flashlight anda pair of sturdy shoessecured to or within reachof everyone’s bed. A goodway to do this is to use adrawstring bag tied to abedpost at the head of thebed for each occupant.(Photo courtesy USGS)24

FOLLOW THE SEVEN STEPS TO EARTHQUAKE SAFETYSTEP 3Prepare Disaster Supply KitsPersonal disaster kitsEveryone in your family should have their own personal disasterkits. These kits are collections of supplies they may need when aquake strikes.Personalize these kits and keep them where they can easily bereached—at home, in the car, at work or school. A backpack orother small bag is best for these kits so that they can be easilycarried in an evacuation. Include the following items:ooMedications, a list of prescriptions, copies of medicalinsurance cards, doctors’ names and contact information.ooMedical consent forms for dependents.ooFirst aid kit and handbook.ooSpare eyeglasses, personal hygiene supplies, andsturdy shoes.ooBottled water.ooWhistle (to alert rescuers to your location).ooEmergency cash.ooPersonal identification.ooList of emergency contact phone numbers.ooSnack foods high in calories.ooEmergency lighting—light sticks and (or) a workingflashlight with extra batteries and light bulbs (handpoweredflashlights are also available).ooComfort items, such as games, crayons, writing materials,and teddy bears.A Special Note About ChildrenBefore the next earthquake, spend time with your kids todiscuss what might occur. Involve them in developing yourdisaster plan, preparing disaster kits (ask them what game ortoy they want to include), and practicing “DROP, COVER, ANDHOLD ON.”In the days after a quake, kids need extra contact andsupport. They may be frightened and under great stress, andaftershocks won’t let them forget the experience. Parents mayhave to leave children with others in order to deal with theemergency, and this can be scary. Whenever possible, includeyour children in the earthquake recovery process.Resources for kids to learn about disaster preparedness: disaster kit(Photo courtesy of American Red Cross)Electrical, water, transportation, and other vital systems canbe disrupted for several days or more after a large earthquake.Emergency response agencies and hospitals will likely beoverwhelmed and unable to provide you with immediateassistance.To help your family cope after a strong earthquake, store ahousehold disaster kit in an easily accessible safe location. Thiskit, which complements your personal disaster kits, should be ina large portable watertight container and should hold at least a3- to 5-day supply of the following items:ooDrinking water (minimum one gallon per person per day).ooFirst aid supplies, medications, and essential hygiene items,such as soap, toothpaste, and toilet paper.ooEmergency lighting—light sticks and (or) a workingflashlight with extra batteries and light bulbs (handpoweredflashlights are also available).ooA hand-cranked or battery-operated radio (and sparebatteries).ooCanned and packaged foods and cooking utensils,including a manual can opener.ooItems to protect you from the elements, such as warmclothing, sturdy shoes, extra socks, blankets, and perhapseven a tent.ooHeavy-duty plastic bags for waste and to serve other uses,such as tarps and rain ponchos.ooWork gloves and protective goggles.ooPet food and pet restraints.ooCopies of vital documents, such as insurance policies andpersonal identification.Note: Replace perishable items like water, food, medications, andbatteries on a yearly basis.For more information on safety, preparedness, anddisaster kits, go to:Telephone book:The front section of your local phone bookBe Ready Utahhttp://beready.utah.govRocky Mountain Power Gas A QUAKE25

WHAT SHOULD I DO?STEP 4Identify Your Building’s PotentialWeaknesses and Begin to Fix ThemIs your house, condo, or apartment strongenough to withstand an earthquake?Use the following quiz to see if your home is likely to be sobadly damaged in a future earthquake that people mightbe injured or that it would be unsafe to occupy. If yourhome scores above 17 on the quiz, you probably shouldhave a structural engineer evaluate it unless it has beenstrengthened in the last few years. The engineer will checkto see if your home is strong enough to keep you and yourfamily reasonably safe in an earthquake by looking for thefollowing:• Is your house properly connected to the foundation?• Is there plywood on the exterior walls of your house?• Are there anchors attaching the roof and floor systemsto the walls?• Is your house constructed out of unreinforced masonry?• Do you have large openings like a garage door that mayrequire better bracing?The following quiz will help you to determine the adequacyof your house in resisting a seismic event. Once you haveidentified the areas requiring retrofitting, prioritize howand when to fix them, and get started. Local buildingdepartments and the Structural Engineers Association ofUtah are excellent resources.Don’t be fooled!—Myth number 5“WE HAVE GOOD BUILDING CODES, SO WE MUST HAVE SAFEBUILDINGS.”The best building code in the world does nothing for buildings builtbefore the code was enacted. Although building codes used in Utahhave strict seismic provisions, many older buildings, particularlyunreinforced masonry buildings, have not been “retrofitted” to meetupdated codes. Retrofitting—fixing problems in older buildings—is the responsibility of a building’s owner.Structural-Safety Quiz forHomes and Other Buildings1. When was your home built?ooBefore 1970 = 6 pointsoo1970 – 1980 = 3 pointsooAfter 1980 = 1 point2. How many stories and what style is your home?oo2 or more stories above grade with stepped floors,split levels, or large openings in floors = 5 pointsoo2 or more stories above grade with flat floors, nosteps in the floor, and no large openings in floors =3 pointsoo1 story rambler above grade = 1 point3. What is the construction material of the exterior walls?ooUnreinforced masonry bearing walls = 7 pointsooWood or reinforced masonry with full height brickveneer = 3 pointsooWood or reinforced masonry = 1 point4. What are the foundation walls constructed from?ooStacked rock or brick, with basement = 5 pointsooStacked rock or brick, no basement = 3 pointooConcrete, with or without basement = 1 pointooSlab on grade, no basement = 0 points5. Where is your house located? (see map, page 8)Total points = __________If your home scores 17 or more points on the quiz, you probablyshould have an engineer, architect, or contractor evaluate it.EXAMPLES:1 pt 3 pts 5 pts 8 pts1. 1958, 1 story, unreinforced masonry, concrete foundation,Salt Lake City: 6+1+7+1+8 = 232. 1995, 2 story (flat), wood (brick veneer), concretefoundation, Ogden: 1+3+3+1+8 = 163. 2006, 2 story (large openings), wood, slab on grade, St.George: 1+5+1+0+3 = 1026

FOLLOW THE SEVEN STEPS TO EARTHQUAKE SAFETYUtah Parapet OrdinanceOn October 28, 1983, two children, ages6 and 7, were killed by falling debrisfrom a parapet (a wall-like barrier at theedge of a roof) on a business in Challis,Idaho, as they walked to school. Challis isabout 13 miles north of the epicenter ofthe 1983 Borah Peak earthquake (magnitude7.3). Photos 1 and 2 were takenof damaged buildings from this earthquakein the nearby town of Mackay,Idaho. These deaths were the firstcaused by an earthquake in the UnitedStates since 65 people were killed in theSan Fernando earthquake in Californiaon February 9, 1971.The 1962 Cache Valley earthquake (magnitude5.7) is another example of fallingdebris from parapets. Arrows in photo3 show the path of bricks that tumbledfrom the parapet of a drugstore onto theroof of the City Cafe in Lewiston, Utah.Luckily this cafe in Lewiston was notopen when the earthquake occurred(see photo 4). Photo 5 shows damage toan unreinforced masonry building in the2008 magnitude 6 Wells, Nevada, earthquake.In response to the damage from pastearthquakes, a parapet-bracing ordinancewas enacted in 1991 in Utah. Thisordinance requires that a licensed engineerevaluate the adequacy of parapetbracing and the connection of the wallsto the roof when a commercial building(built prior to 1975) is to be re-roofed.This ordinance can be found in the StateConstruction Code Administration andAdoption of Approved State ConstructionCode Rule (R156-15A-402).The bracing of parapets, creating strongwall-to-roof connections, and bracing orelimination of other roof appendages(chimneys and cornices) are among thesimplest and most cost-effective seismicupgrades that can be made to a building.The figures at left show how to braceparapets and chimneys. These figuresare based on a State of Utah publicationtitled “The Utah Guide for the SeismicImprovement of Unreinforced MasonryBuildings” and may be viewed onlineat 1 and 2 by O. Kasteler, courtesy ofthe Deseret News; photos 3 and 4 courtesyof the Salt Lake Tribune; photo 5 courtesyof Craig dePolo, Nevada Bureau of Minesand Geology)12345BEFORE A QUAKE27

WHAT SHOULD I DO?STEP 5The previous pages have concentrated ongetting you ready for future earthquakesin Utah, but what should you do when theshaking starts?Protect Yourself DuringEarthquake ShakingIn a public building or theaterDROP, COVER, AND HOLD ON if possible.If in a theater seat, duck down andprotect your head and neck with yourarms. Don’t try to leave until the shakingis over. Then walk out slowly, watchingfor fallen debris or anything that couldfall on you in aftershocks.DROP, COVER, AND HOLD ONIf you are indoors, when you feelstrong earthquake shaking, dropto the floor, take cover under asturdy desk or table, and holdon to it firmly until the shakingstops.If you are indoors...• DROP, COVER, AND HOLD ON. If youare not near a desk or table, drop tothe floor against an interior wall andprotect your head and neck withyour arms.• Avoid exterior walls, windows,hanging objects, mirrors, tallfurniture, large appliances, andcabinets filled with heavy objects.• Do not go outside until well after theshaking stops!In bedHold on and stay there, protecting yourhead with a pillow. You are less likely tobe injured staying where you are. Brokenglass on the floor can cause injuries; besure to put shoes on before stepping onthe floor.In a high-rise buildingDROP, COVER, AND HOLD ON. Avoidwindows. Do not use elevators. Do notbe surprised if sprinkler systems or firealarms activate.At workDROP, COVER, AND HOLD ON. Know yourworkplace’s earthquake safety plan andput it into action. When safe, move to aspecified meeting location.If you are outdoors...Move to a clear area if you can do sosafely; avoid buildings, power lines, trees,and other hazards. Always assume fallenpower lines are live.Near tall buildingsWindows, facades, and architecturaldetails are often the first parts of abuilding to collapse. Get away from thisdanger zone when shaking starts. Takerefuge in a safe building or an openspace.DrivingWhen able, safely pull over to the side ofthe road, stop, and set the parking brake.Avoid overpasses, bridges, power lines,signs, trees, and other things that mightcollapse or fall on the vehicle. Stay insidethe vehicle until the shaking is over. Ifa power line falls on the vehicle, stayinside until a trained person removes thehazard.In a stadiumStay at your seat and protect your headand neck with your arms. Don’t try toleave until the shaking is over. Then exitslowly, avoiding debris and watching foranything that could fall in aftershocks.(Photo courtesy of USGS)Below a damDams can fail during a major earthquake.Catastrophic failure is unlikely, but if youare downstream from a dam, you shouldknow flood-zone information and haveprepared an evacuation plan. For moreinformation on possible flood areas,go to the Utah Division of Water RightsDam Safety Program at, click on the dam of interest, and viewDam Break Map.Don’t be fooled!—Myth number 6“THE TRIANGLE OF LIFE SURVIVALMETHOD IS THE BEST METHOD TO USEINSIDE A BUILDING TO SURVIVE ANEARTHQUAKE.”False. The best survival method inside a buildingis to Drop, Cover, and Hold On under a table, desk,or chair, rather than trying to get into a survivablevoid next to a large, bulky object as advocated bythe Triangle of Life method. The Drop, Cover, andHold On survival method protects individualsfrom objects falling from walls and shelves. Italso provides a level of protection from structuralfailures. If a table or desk is not available, sitdown with your back against an interior wall,using your hands and arms to protect your headand neck.28DURING A QUAKE

FOLLOW THE SEVEN STEPS TO EARTHQUAKE SAFETYSTEP 6After the Earthquake, Checkfor Injuries and DamageAFTERSHOCKGo back toSTEP 5Once earthquake shaking has stopped, followyour disaster preparedness plans (seeStep 2, page 24). Most importantly:Check for injuriesNOTE: The manual in your first aid kit andthe front pages of your telephone bookhave instructions on first aid measures.• Check yourself for serious injuriesbefore helping others. Protect yourmouth, nose, and eyes from dust.• If a person is bleeding, put direct pressureon the wound. Use clean gauzeor cloth, if available.• If a person is not breathing, administerrescue breathing.• If a person has no pulse, begin CPR(cardiopulmonary resuscitation).• Do not move seriously injured persons,unless they are in immediatedanger of further harm.• Cover injured persons with blanketsor additional clothing to keep themwarm.Check for damage causinghazardous conditions• Fire—If possible, put out small fires inyour home or neighborhood immediately.Call for help, but don’t wait forthe fire department.• Gas leaks—Turn off the gas only ifyou suspect a leak because of brokenpipes or detect the odor or sound ofleaking natural gas. Use a manual gasshut-off wrench to close your maingas valve by turning it counterclockwise.Don’t turn gas back on by yourself—waitfor the gas company! (Yourtelephone book has information onthis topic.)• Damaged electrical wiring—Shutoff power at the main breaker switchif there is any damage to your homewiring. Leave the power off until thedamage is repaired! (Your telephonebook also has information on thistopic.)• Downed utility lines—If you seedowned power lines, consider themenergized and keep yourself and otherswell away from them. Never touchdowned power lines or any objects incontact with them!• Falling items—Beware of heavyitems tumbling off shelves when youopen closet and cupboard doors.• Spills—Use extreme caution; when indoubt, leave your home. Spilled medicines,drugs, or other relatively nontoxicsubstances can be cleaned up.Potentially harmful materials, such asbleach, lye, garden chemicals, paint,and gasoline or other flammable liquidsshould be isolated or covered withan absorbent material, such as dirt orcat litter.• Damaged masonry—Stay away frombrick chimneys and walls. They maybe weakened and could topple duringaftershocks. Don’t use a fireplacewith a damaged chimney, as thiscould start a fire or trap toxic gases inyour home.If your home is seriouslydamagedIf your home is structurally unsafe orthreatened by a fire or other secondarydisaster, you need to evacuate. However,shelters may be overcrowded and initiallylack basic services, so do not leavehome just because utilities are out of serviceor your home and its contents havesuffered moderate damage.If you evacuate, tell a neighbor and yourfamily point-of-contact where you aregoing. Take the following, if possible,when you evacuate:Bring to a shelter:ooPersonal disaster supply kits (seeSTEP 3, page 25).ooSupply of water, food, and snacks.ooBlanket, pillow, and air mattress orsleeping pad.ooChange of clothing and a jacket.ooTowel and washcloth.ooDiapers, formula, food, and othersupplies for infants.ooA few family pictures or other smallcomfort items, such as dolls or teddybears for children.ooPersonal identification and copiesof household and health insuranceinformation.ooBooks and games (especially for children).However, do not bring• Pets (service animals for people withdisabilities are allowed—bring foodfor them).• Large quantities of unnecessary clothingor other personal items.• Valuables that might be lost, stolen,or take up needed space.If you suspect a gasleak, use a manualgas shut-offwrench.AFTER A QUAKE29

WHAT SHOULD I DO?STEP 7Once you have met your and your family’simmediate needs after the next strongUtah earthquake, continue to follow yourdisaster-preparedness plan (see Step 2, page24).The first days after the quakeIn the days following a damaging quake,pay special attention to the following:Safety first• Do not re-enter your home until youknow it is safe.• Be sure there are no gas leaks at yourhome before using open flames(lighters, matches, candles, or grills) oroperating any electrical or mechanicaldevice that could create a spark (lightswitches, generators, chain saws, ormotor vehicles).• Check for chemical spills, faulty electricalwiring, and broken water lines.Water in contact with faulty wiring is ashock hazard.• Unplug broken or toppled light fixturesor appliances. These could start fireswhen electricity is restored.• Never use the following indoors: campstoves, kerosene or gas lanterns orheaters, gas or charcoal grills, or gasgenerators, as these can release deadlycarbon monoxide gas or be a fire hazardin aftershocks.Be in communication• Turn on your portable or car radio andlisten for information and safety advisories.• Place all phones back on their cradles.• Call your out-of-area contact, tellthem your status, and then stay off thephone—emergency responders needthe phone lines for life-saving communications.• Check on your neighbors.When Safe, Continue to FollowYour Disaster-Preparedness PlanCheck your food and water supplies• If power is off, plan meals so as to useup refrigerated and frozen foods first. Ifyou keep the door closed, food in yourfreezer may be good for a couple ofdays.• If your water is off, you can drink fromwater heaters, melted ice cubes, orcanned vegetables. Avoid drinkingthe water from swimming pools or hottubs; use it to fight fires.The first weeks after theearthquake• This is a time of transition. Althoughaftershocks may continue, you willnow work toward getting your life,your home and family, and your routinesback in order. Emotional careand recovery are just as important ashealing physical injuries and rebuildinga home. Make sure your home is safe tooccupy and not in danger of collapse inaftershocks. If you were able to remainin your home or return to it after a fewdays, you will have a variety of tasksto accomplish while re-establishingroutines:Tasks• If your gas was turned off, you will needto arrange for the gas company to turnit back on.• If the electricity went off and thencame back on, check your appliancesand electronic equipment for damage.• If water lines broke, look for waterdamage.• Locate or replace critical documentsthat may have been misplaced, damaged,or destroyed.• Contact your insurance agent or companyto begin your claims process.• Contact the Federal Emergency ManagementAgency (FEMA) to find outabout financial assistance. For FEMAAFTERSHOCKGo back toSTEP 5teleregistration, call 1-800-621-FEMA(3362).• If you cannot live at your home, set upan alternative mailing address with thepost office.If you can’t stay in your homeThe American Red Cross offers immediateemergency assistance with housing needs.The Red Cross also supports shelter operationsprior to a presidential declaration ofa federal disaster.Once a presidential declaration has beenissued, FEMA may activate the Assistancefor Individuals and Households Program.This program includes:• Home-repair cash grants; the maximumfederal grant available is $28,800 for allindividual and family assistance.• Housing assistance in the form ofreimbursement for short-term lodgingexpenses at a hotel or motel.• Rental assistance for as long as 18months in the form of cash paymentfor a temporary rental unit or a manufacturedhome.• If no other housing is available, FEMAmay provide mobile homes or othertemporary housing.FEMA mobile homes being set up in Port Charlotte,Florida, to provide temporary housingfor victims of Hurricane Charley (August 2004).Nearly a year after the storm, these trailers werestill being used. (Photo courtesy of FEMA)30AFTER A QUAKE

WHAT ELSE SHOULD I KNOW?A Review of Money Matters:Financial Impacts of EarthquakesFollowing a quake, disaster aid may not be immediately available, so you shouldplan ahead. If you have prepared a financial disaster recovery plan, you are morelikely to recover successfully after a quake. Financial recovery planning resourcesare available from:• Operation Hope Emergency Financial First Aid Kit:• American Red Cross—Disaster Recovery: A Guide to Financial Issues (2003):• Federal Emergency Management Agency (FEMA):• Small Business Administration: financial disaster recovery kitAfter a damaging earthquake, you will need copies of essential financial documents, as wellas emergency cash. Keep these items together, current, and stored in a fire-proof documentsafe. Consider purchasing a home safe or renting a safe deposit box. Some essential itemsin your financial disaster recovery kit are:ooBirth certificates.ooInsurance policies.ooMarriage license/divorce papers and ooAn inventory of your householdchild custody papers.possessions.ooPassports and driver’s licenses. ooAppraisals of valuable jewelry, art,ooSocial security cards.antiques, and heirlooms.ooNaturalization papers and residency ooHome improvement records.documents.ooA backup of critical files on yourooMilitary/veteran’s (also keep a copy at work).ooCritical medical information. ooA list of names, phone numbers, andooCash, in the event ATM or banke-mail addresses of critical personalservices are disrupted.and business contacts.ooCertificates for stocks, bonds, and ooDeeds, titles, and other ownershipother investments.records for property such as homes,ooBank, RVs, and boats.ooCredit card numbers.ooPowers of attorney, including healthcarepowers of attorney.ooA list of phone numbers for financialinstitutions and credit card companies ooWills or trust documents.where you have accounts.For help in the first week after anearthquake, contact:Your county office of emergency servicesAmerican Red Cross:http://utahredcross.org1-800-328-9272Utah Division of Emergency Management: Emergency Management Agency(FEMA):’t be fooled!—Myth number 7“I DON’T NEED TO WORRY ABOUTEARTHQUAKES—THE GOVERNMENT WILL SAVE ME!”Many people wrongly believe that the U.S.government will take care of all their financialneeds if they suffer losses in an earthquake. Thetruth is that federal disaster assistance is onlyavailable if the president formally declares adisaster. Even if you do get disaster assistance,it is usually a loan that you must repay, withinterest, in addition to mortgages and otherfinancial obligations you still owe, even ondamaged property. If you don’t qualify for loans,grants may be available to you. However, theseare only designed to meet your most immediateneeds, not to replace your losses (see pages 18and 19).31

WHAT ELSE SHOULD I KNOW?Earthquake Informationon the WebAfter an earthquake, knowing more about whatjust happened can reduce fears and help youunderstand what to expect next. Online earthquakeinformation products include:Location and magnitude of recentearthquakesWithin 1 to 2 minutes of an earthquake, its locationand magnitude are available at several Web sites,including:“ShakeMap”Within 5 to 10 minutes of most felt earthquakes(magnitude 3.0 and greater in the Wasatch Frontarea), a “ShakeMap” is posted on the Web. This mapshows the range of shaking intensities across aregion. Every quake has only a single magnitude,but it produces a wide range of shaking intensityvalues over the area in which it is felt.ShakeMaps use data from seismic instrumentsto provide a rapid picture of where the strongestshaking occurred. These maps help to identifyareas where a quake’s impact is greatest and areused by emergency managers to speed disasterresponse. ShakeMaps are available at:“Did You Feel It?”—Tell us what you felt!Personal experiences of the effects of an earthquakeare very valuable to scientists. When youhave felt a quake, please report your observationsby using a quick survey found on the U.S.Geological Survey “Did You Feel It?” Web site at you fill out the survey, your observationsof actual damage and shaking are combinedwith those of thousands of other people. Thequake’s shaking intensities, derived from theseobservations, are displayed by ZIP code on a“Community Internet Intensity Map.”Who monitors Utah’s earthquakes?Seismic monitoring in the Utah region is conductedby the University of Utah Seismograph Stations inpartnership with the U.S. Geological Survey as part of theAdvanced National Seismic System.For more information go to:”ShakeMap” for theDecember 2006quake nearKaysville, Utah.Map of recent earthquakesin the Wasatch Front andYellowstone Park regions,one day after a magnitude3.4 quake 20 miles east–northeast of Kaysville, Utah,on December 20, 2006.Community Internet Intensity Map(“Did You Feel It?”) for the December2006 quake near Kaysville, Utah.Although the quake originatedunder the Wasatch Range, itproduced light shaking along theWasatch Front from Ogden to SaltLake Valley. More than 400 peoplereported their observations on thisquake online.32

WHAT ELSE SHOULD I KNOW?GlossaryAftershocks. Earthquakes that followthe largest shock of an earthquakesequence. They are smaller than the“mainshock” and can occur over aperiod of weeks, months, or years. Ingeneral, the larger the mainshock,the larger and more numerous theaftershocks and the longer they willcontinue.Crust. Earth’s outermost layerconsisting of rigid oceanic andcontinental tectonic plates.Epicenter. The point on Earth’s surfaceabove where an earthquake begins atdepth in Earth’s crust.Fault. A fracture or crack along whichthe two sides slide past one another.Fault rupture. The area of Earththrough which fault movement occurrsduring an earthquake. For largequakes, the section of the fault thatruptures may be several hundred milesin length. Ruptures may or may notextend to the ground surface.Fault scarp. A steep, linear break orslope formed where a fault rupturesthe ground surface.Fault segment. A part of a fault that isthought to rupture independently ofother parts of the fault. One or moresegments may rupture in a singleearthquake.Foreshock. An earthquakethat precedes the largest quake(“mainshock”) of an earthquakesequence. Foreshocks may occurseconds to weeks before themainshock. Not all mainshocks arepreceded by foreshocks.Intensity. A measure of groundshaking describing the local severityof an earthquake in terms of its effectson Earth’s surface and on humansand their structures. The ModifiedMercalli Intensity scale, which usesRoman numerals, is one way scientistsmeasure intensity.Landslide. A mass movement of soil,mud, and (or) rock down a slope.Liquefaction. The process thatoccurs when an earthquake shakeswet sandy soil until it behaves like aliquid, allowing sand to “boil up” to thesurface, buildings to sink, or slopingground to move.Magnitude (M). A number thatrepresents the size of an earthquake,as determined from seismographicobservations. An increase of one unitof magnitude (for example, from 4.6to 5.6) corresponds approximately to athirty-fold increase in energy released(by definition, a two-unit increase inmagnitude —for example, from 4.7to 6.7—represents a thousand-foldincrease in energy). Quakes smallerthan magnitude 2.5 generally are notfelt by humans.Mainshock. The largest quake ofan earthquake sequence, possiblypreceded by smaller foreshocks andcommonly followed by aftershocks.Mantle. The layer of heated viscousrock between Earth’s crust and core.Normal fault. An inclined fault alongwhich the upper side moves downwardrelative to the lower side. Utah’sWasatch fault is a good example.Parapet. A wall-like barrier at the edgeof a roof.Retrofit. Strengthening an existingstructure to improve its resistance tothe effects of earthquakes.Seiche. Waves “sloshing” in a lake as aresult of earthquake ground shaking.Waves caused by landsliding into areservoir or displacement of the lakebed are termed a surge.Seismic hazard. The potentialfor damaging effects caused byearthquakes. The level of hazarddepends on the magnitude andfrequency of likely quakes, the distancefrom the fault that could cause quakes,and geologic conditions at a site.Seismic risk. The chance of injury,damage, or loss resulting from seismichazards. There is no risk, even in aregion of high seismic hazard, if thereare no people or property that couldbe injured or damaged by a quake.Seismograph. A sensitive instrumentthat detects and records seismic wavesgenerated by an earthquake.Strike-slip fault. A generally nearverticalfault along which the two sidesmove horizontally past each other. Themost famous example is California’sSan Andreas fault.Surface faulting (surface faultrupture). Propagation of anearthquake-generating fault rupture tothe surface, displacing the surface andforming a fault scarp.Tectonic plate. Earth’s outer shell iscomposed of large, relatively strong“plates” that move relative to oneanother. Movements on the faults thatdefine plate boundaries produce mostearthquakes.Tectonic subsidence. Downdroppingand tilting of a basin floor on thedowndropped side of a fault during anearthquake.33

ONLINE RESOURCESWhy should I care? (pages 1-11)Earthquakes & Utah: of Fault Movement in the Western United States: Earthquakes in Utah: and Geologic Hazards: Information Center: of Utah Seismograph Stations: http://quake.utah.eduUtah Geological Survey: http://geology.utah.govUtah Seismic Safety Commission: http://www.ussc.utah.govU.S. Geological Survey Earthquake Hazards Program: should I prepare? (pages 12-19) and What should I do? (pages 20-30)American Red Cross: www.utahredcross.orgBe Ready Utah: http://beready.utah.govCitizen Corps: http://citizencorps.utah.govFederal Emergency Management Agency: http://www.fema.govStructural Engineers Association of Utah: http://www.seau.orgU.S. Department of Homeland Security: Association of Contingency Planners: http://utah.acp-international.comUtah Division of Emergency Management: else should I know?(pages 31-33)Did you feel it? – Report it!: ShakeMaps: ORGANIZATIONSUSGSscience for a changing world

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