SURVEY NOTESU T A H G E O L O G I C A L S U R V E Y

Vo l u m e 3 5 , N u m b e r 1 J a n u a r y 2 0 0 3

U R B A N G R O W T H A N D

I N C R E A S E D H A Z A R D V U L N E R A B I L I T Y

Table of Contents

Several articles in this issue of Sur-vey Notes highlight the rapidurban growth along the Wasatch

Front and the increased vulnerabilityfrom geologic hazards. Utah had thefourth highest population growth inthe country last decade (29%), withmost growth occurring along the Inter-mountain seismic belt. Because ofthis, the state has the seventh highestannualized earthquake loss rate ($51million). The growth statistics for the1990s highlight another trend – that ofrapid urbanization occurring withinthe Wasatch Range, compared to thetraditional growth areas along the val-ley floors and benches adjacent to themountain fronts in northern andsouthern Utah. The county with thehighest growth rate during the 1990swas Summit County (92%), with ParkCity being its largest city. This trendtowards building in steeper terrain hasincreased the risk of forest fire haz-ards, and the associated subsequentrisks of debris flows. Repeateddroughts in recent years have com-pounded these risks, with severaldamaging debris flows occurring thisyear (see Rich Giraud’s article on theSantaquin debris flow).

The UGS endeavors to warn andadvise local governments and theircity planners on the risks of geologichazards as new subdivisions are beingplanned. Unfortunately geologic haz-ards are not always a high prioritywhen all the other growth pressuresare also taken into consideration. Thisyear’s debris flows near Alpine (just

north of Provo), and at Santaquin (justsouth of Provo), demonstrated thatpeople are most receptive to messagesabout geologic hazard vulnerabilitywhen damaging events actually occur.Provo City is now taking advantage ofa grant from the Emergency Water-shed Protection program of the NRCSto reduce the debris-flow hazard fromBuckley Draw which also burned lastsummer, but fortunately missed expe-riencing any severe summer down-pours. The Santaquin debris flowswere not triggered by the storm of thecentury; the 0.27 inches of rain that fellin probably less than 15 minutes couldoccur anywhere along Wasatch Frontonce every few years. The UGS is cur-rently working with the NationalWeather Service on compiling a pack-age of educational materials based onthe Santaquin debris flows to capital-ize on the window of opportunity andincrease the awareness of city plannersand the public.

On another topic, starting January 1,2003, anyone practicing geology beforethe public in Utah requires a profes-sional geologist license. The “grandfa-ther” period when the ASBOG exam isnot required extends until January 1,2004. During this time applicants stillmust meet educational and workexperience standards to receive alicense. Information about applyingfor licensure can be found at the StateDivision of Occupational and Profes-sional Licensure website:http://www.dopl.utah.gov/licens-ing/geologist.html.

The Director’sPerspectiveby Richard G. Allis

State of UtahMichael O. Leavitt, Governor

Department of Natural ResourcesRobert Morgan, Executive Director

UGS BoardRobert Robison, ChairGeoff Bedell Craig NelsonE.H. Deedee O’Brien Charles SemborskiSteve Church Ron BruhnKevin Carter (Trust Lands Administration-ex officio)

UGS StaffAdministration

Richard G. Allis, DirectorKimm Harty, Deputy DirectorJohn Kingsley, Assoc. DirectorDaniel Kelly, Acct. OfficerBecky Wilford, Secretary/ReceptionistJo Lynn Campbell, Admin. SecretaryLinda Bennett, Accounting Tech. Michael Hylland, Tech. Reviewer

Survey Notes StaffEditor: Jim StringfellowEditorial Staff: Vicky Clarke, Sharon HamreCartographers: James Parker, Lori Douglas

Geologic Hazards Gary ChristensonWilliam Lund, Barry Solomon, Francis Ashland, Richard Giraud, Greg McDonald, Justin Johnson

Energy and Mineral Resources David TabetRobert Gloyn, Robert Blackett, Roger Bon, Thomas Chidsey, Bryce T. Tripp, Craig Morgan,J. Wallace Gwynn, Jeff Quick, Kevin McClure, Sharon Wakefield, Carolyn Olsen, Cheryl Gustin, Tom Dempster, Mike Kirschbaum,Brigitte Hucka

Geologic Mapping Grant WillisHellmut Doelling, Jon King, Bob Biek, Kent Brown, Michael Wright,Basia Matyjasik, Douglas Sprinkel

Geologic Information and OutreachSandra Eldredge, William CaseChristine Wilkerson, Mage Yonetani, Patricia Stokes, Mark Milligan, Carl Ege, Rob Nielson, Jeff Campbell

Environmental Sciences Michael Lowe James Kirkland, Charles Bishop, Janae Wallace, Martha Hayden, Hugh Hurlow, Kim Nay,Don DeBlieux, Matt Butler

Maps Show Potential Geologic Effects ofa Magnitude 7 Earthquake . . . . . . . . 1

Debris Flows in Utah . . . . . . . . . . . . . . 4What About Great Salt Lake? . . . . . . . 5Fire-Related Debris Flows Damage

Houses . . . . . . . . . . . . . . . . . . . . . . . . . 6New Utah Minerals . . . . . . . . . . . . . . . . 7Survey News . . . . . . . . . . . . . . . . . . . . . 7Energy News . . . . . . . . . . . . . . . . . . . . . 8Glad You Asked . . . . . . . . . . . . . . . . . . . 9GeoSights . . . . . . . . . . . . . . . . . . . . . . . 10Triggered Seismicity in Utah from the

Denali Fault Earthquake . . . . . . . . . 11Teacher’s Corner . . . . . . . . . . . . . . . . . 13

Design by Vicky Clarke

Cover: Salt Lake City skyline. Photographby Frank Jensen, courtesy of the Utah TravelCouncil.

ISSN 1061-7930

Survey Notes is published three times yearly by Utah Geological Survey, 1594 W. North Temple, Suite 3110, Salt Lake City, Utah84116; (801) 537-3300. The UGS is an applied scientific agency that creates, evaluates, and distributes information about Utah’sgeologic environment, resources, and hazards to promote safe, beneficial, and wise use of land. The UGS is a division of theDepartment of Natural Resources. Single copies of Survey Notes are distributed free of charge to residents within the UnitedStates and Canada and reproduction is encouraged with recognition of source.

IntroductionIn 1860, essayist and poet RalphWaldo Emerson wrote, “We learngeology the morning after the earth-quake, on ghastly diagrams of clovenmountains, upheaved plains, and thedry bed of the sea.” Human natureremains the same now as then—weoften learn our geologic lesson afteran earthquake, rather than plan inadvance. The seismically active cen-tral Wasatch Front of Utah, with apopulation of about 1.7 million cen-tered upon Salt Lake City, has thepotential to be shaken by a strong(magnitude 7) earthquake. However,the region has not experienced astrong earthquake in historical time.To help understand earthquake risksand estimate losses in the region, wemapped geologic hazards posed by amagnitude 7 earthquake along theSalt Lake City segment of the Wasatchfault zone, a major active zone of nor-mal faulting.

Federal, state, and private-industrypartners cooperated in this study, par-tially funded by the U.S. GeologicalSurvey’s National Earthquake Haz-ards Reduction Program and withadditional support and technicalassistance from the Utah Division ofEmergency Services and HomelandSecurity, URS Corporation, and PacificEngineering & Analysis. Our hazardmaps will provide the geologic basisfor a comprehensive loss estimate

using HAZUS computer software,which was developed for the FederalEmergency Management Agency foruse in estimating losses and planningfor emergency preparedness,response, and recovery.

The earthquake hazards we mappedinclude surface fault rupture, tectonicsubsidence, earthquake ground shak-ing, liquefaction, and earthquake-induced landsliding. Most hazardswere mapped by considering thethickness of unconsolidated deposits(“soil” to geologists and engineers),rock and soil properties, and the rela-tionship of thickness and properties toeffects observed in historical earth-quakes worldwide.

The Scenario EarthquakeThe Wasatch fault zone trends north-south through the Wasatch Front andis divided into 10 segments, includingthe Salt Lake City segment. Geologicevidence indicates that the Salt LakeCity segment generates large earth-quakes (approximately magnitude 7)on average every 1,350 years, themost recent having been about 1,300years ago. Because a large earthquakeon the Salt Lake City segment willaffect the greatest number of peopleand probably produce the greatestlosses along the central WasatchFront, we selected a magnitude 7event on this segment as the scenarioearthquake.

Mapped Earthquake Hazards fromthe Scenario Earthquake

Surface fault rupture: Movementalong faults deep within the earthgenerates earthquakes. In Utah, if theearthquake is strong enough, com-monly greater than magnitude 6.5, thefault movement will break to theground surface. Along the Wasatchfault zone, this surface fault rupturewill form a near-vertical scarp as oneside of the fault is uplifted and theother side is downdropped. We esti-mate an average scarp height of 6.1feet where faulting occurs along theEast Bench of Salt Lake Valley. Thisamount of displacement is capable ofcausing irreparable damage to anystructure built across the scarp. Azone of additional deformation willlikely accompany the main scarp onits downthrown side.

SU RV E Y NO T E S 1

A strong earthquake in the Salt Lake Cityarea may create a fault scarp similar to this,formed during the 1983 Borah Peak earth-quake in Idaho.

New Maps Show Potential GeologicEffects of a Magnitude 7 Earthquakein the Salt Lake City Area

by Barry J. Solomon

SU RV E Y NO T E S2

Peak horizontal ground accelerations resulting from a M 7 scenario earthquake along the Salt Lake City segment of the Wasatch fault zone.

Tectonic subsidence: When earth-quake faults break the ground surfacein a geologic setting like the WasatchFront, the adjacent valley floor maydrop down and tilt towards the fault,creating a subsidence trough. Theextent of tilting is controlled by theamount and length of surface faultdisplacement.

When the Salt Lake Valley floor tiltsduring the scenario earthquake, theshoreline of Farmington Bay in GreatSalt Lake will shift to the southeast.Developed areas near the lake shoreand in the northern Jordan Riverflood plain may be flooded if the levelof Great Salt Lake is high when shift-ed. Subsidence may also cause local-ized ponding of shallow groundwater east of the Jordan River in SaltLake Valley.

Ground shaking: Ground shaking isthe most widespread hazard resultingfrom the scenario earthquake. Nor-mally, a building need only withstandthe vertical force of gravity (assignedan acceleration value of 1 g) to sup-port its own weight. However, dur-ing an earthquake a building is alsosubjected to horizontal accelerationsfrom ground shaking. These accelera-tions have the potential to cause dam-age to weak structures (buildings notspecifically designed to resist earth-quakes) if they are greater than 0.1 g,and damage potential increases withthe strength of ground motions.

During our scenario earthquake,potentially damaging ground motionsextend north to Ogden and south toProvo at distances of 30 to 40 milesfrom Salt Lake City. The strength ofground motions rapidly decreaseswith increasing distance from thefault on its upthrown side in theWasatch Range, although potentiallydamaging ground motions may occurin the mountain valleys. Potentiallydamaging ground motions are ampli-fied in certain deposits of sand andgravel, particularly those present onthe east side of Salt Lake Valley.

Liquefaction: Liquefaction occurswhen ground shaking is strongenough to cause shallow, water-satu-

rated, cohesion-less soils (com-monly sand) tolose their strengthand ability tosupport theweight of overly-ing soil and struc-tures. Liquefac-tion is one of themajor causes ofearthquake dam-age.

During our sce-nario earthquake,much of Salt LakeValley and nearbyareas has a poten-tial for large later-al (possibly greater than 1 foot) andvertical (possibly greater than 8 inch-es) liquefaction-induced ground dis-placements. Research suggests thatdamage may be severe from grounddisplacements this large, and much ofthe damage may be irreparable.However, the extent of soils havingthe potential for large liquefaction-induced displacements is deceiving.Their widespread distribution is dueto the high levels of ground shakingresulting from the scenario earth-quake, which can cause large dis-placements even in soils that are notusually prone to liquefaction.Although possible, large displace-ments are unlikely in southern SaltLake Valley, but are most likely in thedensely populated northern part ofthe valley, the west Bountiful area,and the northern end of Utah Valley.

Landsliding: Another geologic hazardthat may be caused by earthquakeground shaking is landsliding. Slopesconsidered unstable under normalconditions will be even less stableduring moderate to strong earth-quakes, and some slopes that are nor-mally stable may also fail as a resultof earthquake ground shaking, partic-ularly if wet. Landslides can damagebuildings, transportation routes, andutility lines by displacement of theground, and cause flooding due todischarge of springs and damming ofstreams.

During our scenario earthquake, land-sliding will likely be most severe onmountain spurs of the Wasatch Rangeadjacent to Salt Lake Valley, threaten-ing downslope development in areassuch as the East Bench. However,prehistoric landslide deposits are rela-tively rare on these slopes, suggestingthat landslides have not commonlyoccurred during previous large earth-quakes in Salt Lake Valley. Landslid-ing may also occur along steep banksof the Jordan River in southern SaltLake Valley and, to a lesser extent, inthe Oquirrh Mountains to the west,the Traverse Range to the south, andthe Wasatch Range interior to the east.Because landsliding is more commonunder wet conditions, the hazard willbe greatest from a springtime earth-quake during snowmelt.

A Tool for the FutureOur geologic-hazard maps, availablepublicly later this year, demonstratethe widespread effects in the centralWasatch Front of the scenario earth-quake. However, we don’t have towait until, as Emerson wrote, “afterthe earthquake” to learn our lesson.We hope that these maps provide abasis to better understand earthquakerisks and encourage loss reduction inUtah before the next strong earth-quake happens. Being prepared is amuch better choice than waiting idlyby for disaster to strike.

SU RV E Y NO T E S 3

A landslide caused by the 1992 St. George earthquake destroyed thishouse in Springdale.

Debris flows are fast-moving slurries of rock, mud, organ-ic matter, and water that flow down steep mountain chan-nels and then spread out and come to rest on alluvial fans.Debris flows are triggered by rapid snowmelt or intensethunderstorm rainfall. Alluvial fans at the mouths ofmountain drainages have gentle slopes and are favoredsites for housing and other development. However, whendebris flows travel out onto alluvial fans they can be life-threatening and destructive because they can occur withlittle warning, cause flooding and burial by debris, andhave impact pressures large enough to push houses offfoundations and collapse walls. Large-volume, destruc-tive debris flows on alluvial fans are best described as rel-atively low-probability, high-consequence events wherethe time period between debris flows is often a period ofdeceptive tranquility.

Since the state was settled by pioneers in 1847, debrisflows in Utah caused 14 deaths and substantial propertydamage. One notable debris flow, the 1983 Rudd Canyondebris flow in Farmington, damaged 50 homes and caused$3 million in damage. Many areas of the Wasatch Frontare particularly at risk from future debris flows, because ahigh population density exists on alluvial fans where noprotective measures have been taken.

A debris-flow-hazard evaluation is necessary when devel-oping on geologically young alluvial fans to ensure safedevelopment. To help provide for consistent and system-atic debris-flow-hazard evaluations, the Utah GeologicalSurvey is preparing a report titled “Guidelines for theGeologic Evaluation of Debris-Flow Hazards on AlluvialFans in Utah.” These guidelines will assist geologists inevaluating debris-flow hazards. The purpose of a debris-flow-hazard evaluation is to determine if a hazard existsand, if so, to provide geologic information needed todesign risk-reduction measures. The guidelines focus thehazard assessment on two specific areas: the drainagebasin and the alluvial fan. For most hazard assessmentsflow volume is the most important factor in addition toflow frequency, impact pressure, runout distance, and sed-iment burial depth.

Debris flows start high in the drainage basin and increase

in volume as they travel down channels, scouring andincorporating sediment. Geologists can estimate potentialdebris-flow volume by assessing the sediment-supply con-ditions in the drainage basin. Therefore, the hazard evalu-ation of the drainage basin focuses on the channel sedi-ment supply, erosion conditions, and surface-water runoffconditions that ultimately determine the volume of mate-rial that reaches the alluvial fan. Study of historical debrisflows indicates 80 to 90 percent of the debris-flow volumeis eroded from channels; therefore, determining the vol-ume of available channel sediment is critical to the hazardevaluation. The amount of sediment stored along chan-nels is estimated by field surveys of channels in the

Debris Flows in Utah – Debris Flows in Utah – New Guidelines for Hazard EvaluationNew Guidelines for Hazard Evaluation

By Richard Giraud

SU RV E Y NO T E S4

Aerial view, looking northeast, of the September 7, 1991 Cameron Covedebris flow in North Ogden (photo taken in August 1996).

mouth of canyon

alluvial fanalluvial fan

1991 debris-flow

deposit

SU RV E Y NO T E S 5

Seiches (pronounced “sayshes”) are oscillations of enclosedbodies of water, similar to the sloshing of water in a bathtub.The term was first used in 19th century Switzerland to applyto standing waves set up on the surface of Lake Geneva bywind and changes in barometric pressure. However, seichesoften occur following an earthquake. Although strong groundshaking most commonly causes earthquake seiches, more dra-matic seiching motion may be produced by a permanent verti-cal ground displacement beneath a water body, such as maybe caused by surface faulting or tectonic subsidence. Thesewaves are sometimes called “surges” to differentiate themfrom much milder but otherwise similar oscillations of closedwater bodies caused by ground shaking.

Recent interest in possible seiches in Great Salt Lake resultsfrom the potential for lakeshore flooding associated with his-torically high lake levels in the early 1980s. Possible seicheswere first discussed in this context by the University of UtahSeismograph Stations in an analysis of earthquake-designconsiderations for the inter-island diking project, whichdescribed accounts of waves generated in Great Salt Lake bythe 1909 magnitude 6+ Hansel Valley, Utah earthquake.Although felt reports placed the location of the 1909 earth-quake about 9 miles northeast of the north lake shore, the

accounts of waves generated by this event suggested that theearthquake might actually have occurred beneath the lake andcaused displacement of the laµke bottom, generating a surge.The larger 1934 magnitude 6.6 Hansel Valley earthquakeapparently did not generate similar lake waves, consistentwith instrumental location of the earthquake epicenter andwith surface faulting located just northeast of the north lakeshore.

The height of the wave generated by the 1909 Hansel Valleyearthquake was later estimated at more than 12 feet using ele-vations of Great Salt Lake and the Lucin Cutoff railroad tres-tle, which was overtopped by the wave. However, this esti-mate did not consider the cause of the wave. The estimate isnow believed to be an example of the potential for waves gen-erated by differential subsidence of the lake floor associatedwith one of several active faults underlying the lake. Thus,when describing the consequences of an earthquake with aspecified magnitude and location (a scenario earthquake), themechanism of wave generation is important to consider anddepends upon the relative locations of the lake, earthquake epi-center, and surface fault rupture. In the case of our scenario,neither a surge from displacement of the lake bed nor a seichefrom ground shaking will be significant.

drainage basin.

Debris-flow deposits on alluvial fansprovide a record of past flow volumesand runout. The hazard evaluationon alluvial fans follows the idea thatthe general areas where debris flowshave deposited sediment in the recentgeologic past are where they will like-ly deposit sediment again in thefuture. Alluvial fans are landformscomposed of a mixture of debris-flowand stream-flow deposits. Geologistsdescribe and analyze the debris-flowdeposits exposed in subsurface exca-vations to understand past debrisflows, including estimating how fre-quently debris flows occur, typicalvolumes of past flows, typical sedi-ment burial depths, and runout dis-tances on different parts of the allu-vial fan. By understanding thebehavior of past flows, geologists canestimate the hazard that future debrisflows might present.

Wildfires in the drainage basinincrease the debris-flow hazardthrough loss of vegetation and cre-

ation of water-repellent soil condi-tions that promote rapid runoff dur-ing thunderstorm rainfall orsnowmelt. Recent wildfires thatburned drainages above the WasatchFront communities of Santaquin,Provo, and Springville requiredimplementing emergency measuresbecause debris-flow hazards had notbeen addressed in some residentialdevelopments below the burnedareas. Fire-related debris flows haverecently occurred in the followingareas:

• Lake Point, Big Canyon debrisflow, 8/23/00, Barrow Pit fire;

• Vivian Park/South Fork ProvoRiver, South Fork debris flow,8/31/00, Wasatch fire complex;

• Alpine, Preston Canyon debrisflows, 8/21/01 and 9/6/02, OakHills fire; and

• Santaquin and Spring Lake, DryMountain debris flows, 9/12/02,Mollie fire (see related article inthis issue).

Historical records of debris flows inUtah have shown the flows to behighly variable in terms of size, mate-rial properties, and runout distance;therefore, conservative design param-eters must be used in risk reduction.The guidelines focus on obtaininggeologic information to understandand describe the hazard to helphydrologists and engineers model thehazard and design risk-reductionmeasures.

The August 23, 2000, Big Canyon fire-relateddebris flow above Lake Point. Greg McDon-ald, a UGS geologist, is taking measurementsto determine the volume of the flow on thealluvial fan.

WWhhaatt AAbboouutt GGrreeaatt SSaalltt LLaakkee??by Barry J. Solomon

SU RV E Y NO T E S6

On the evening of September 12, 2002, intense thunder-storm rainfall on Dry Mountain, about 18 miles south ofProvo, triggered fire-related debris flows that traveleddown drainages and onto alluvial fans, damaging housesand property in Spring Lake and Santaquin east of Inter-state 15. Fire-related debris flows are debris flows thatstart in areas burned by wildfires. Wildfires can produceconditions favorable for debris flows because they exposebare soil to erosion by burning vegetation and creatingwater-repellent soil conditions that promote rapid runoff.The September 12, 2002, fire-related debris flows startedhigh in the drainages of Dry Mountain that burned in the2001 Mollie wildfire, a human-caused fire that burned8,000 acres between August 18 and September 1, 2001.

The storm was relatively short in duration, only dropping0.27 inches of rain. However, it was preceeded by severaldays of light rain that kept soils wet and promoted runoff,triggering multiple debris flows on the west flank of DryMountain. Three debris flows deposited sediment in sub-divisions built on alluvial fans in Spring Lake and San-taquin, and others deposited sediment in undevelopedareas. The debris flows were typical of other historicaldebris flows in Utah, occurring with little warning andtraveling quickly down the channels and onto alluvialfans. Homeowners had little time to react. One flow inSpring Lake filled part of the High Line irrigation canalwith sediment, causing flooding in addition to debris-flowdamage.

Fire-Related Debris Flows Damage Housesin Spring Lake and Santaquin, Utah

by Richard Giraud and Greg McDonald

Sediment deposited at the intersection of Lambert Avenue and AppleView Street in Santaquin. The debris flow moved cars and filled base-ments with sediment.

The debris-flow impact broke through the basement window of thishouse on Apple View Street in Santaquin.

The debris flow entered the front and garage doors of this house onPeach Street in Santaquin.

The debris flow broke through the back wall of this house on PeachStreet in Santaquin.

SU RV E Y NO T E S 7

The most damaging debris flow traveled through a subdi-vision in Santaquin that was evacuated immediately afterthe event. This debris flow moved and partially buriedseveral vehicles, broke through a house wall, and enteredother houses through broken basement windows anddoors. Debris-flow impacts also tore gas meters from theirmounts, causing gas leaks and a small fire. The majorityof house damage was due to sediment and water flowinginto houses. Sediment flow and burial on lots also dam-aged landscaping and property outside the houses. Theflow did not follow city streets, but rather flowed aroundhouses and through lots.

Following the Mollie fire in September 2001, an assessmentof post-burn conditions on Dry Mountain by state and fed-eral agencies, including the Utah Geological Survey, identi-

fied an increased debris-flow and flood hazard to the sub-divisions on the alluvial fans. These agencies recommend-ed that local communities perform a more detailed hazardevaluation to determine where emergency measures werenecessary. These agencies also noted that debris-flow andflooding hazards existed in these areas before the fire, andthat efforts to address the short-term hazards related to thefire should also consider the long-term potential of debrisflows and floods. The homes and subdivisions apparentlywere constructed without regard to the debris-flow haz-ard. Because no emergency measures were taken to divertor contain flows to protect houses and property inresponse to recommendations in 2001, both short- andlong-term debris-flow hazards remain. Local communitiesare now planning to take active defensive measures.

Survey News

New Utah Minerals

Cheryl Ostlund has transferred to DNR Parks NorthwestRegion Office for an interesting change of scenery. Herposition of Administrative Secretary has been assumed byJo Lynn Campbell lately with the Geologic Informationgroup.

Neil Storey has left the Hazards group to join CH2M-Hillas a GIS analyst. His position has been filled by JustinJohnson, formerly with the Division of Water Resources.

Pat Speranza, after 18 1/2 years as a cartographer in Editor-ial, has transferred her affections to Florida. Best of luck,Pat.

Orthominasragrite, V4+O(SO4)(H2O)5

Orthominasragrite is a vanadium sulfate found at theNorth Mesa mine group in the Temple Mountain miningdistrict, Emery County. The mineral is found as roundedaggregates approximately 0.002 mm across. Orthominas-ragrite is pale blue to bright blue with a pale blue streak.The mineral has a hardness of 1 and a density of 2.00g/cm3.

Orthominasragrite occurs in a fossilized log in the Shi-narump Conglomerate Member of the Triassic Chinle For-mation. The mineral is associated with pyrite, sulfur,minasragrite, and undescribed vanadium sulfate.Orthominasragrite is named for its relationship with themineral minasragrite.

Oswaldpeetersite, (UO2)2CO3(OH)2 · 4H2O

Oswaldpeetersite is a basic uranyl carbonate found at theJomac uranium mine in San Juan County. The mineral isfound as prismatic crystals in radiating groups. Individ-ual crystals are approximately 0.1 mm long and 0.01 mmwide. Oswaldpeetersite is canary yellow and has a pale

yellow streak. The mineral has a hardness between 2 and3 and a density greater than 4.10 g/cm3. Oswaldpeeter-site also occurs in the Shinarump Conglomerate in a fos-silized log. The mineral is associated with gypsum,cuprite, goethite, antlerite, lepidocrocite, mbobomkulite,hydrombobomkulite, sklodowskite, and two undefineduranium minerals. Oswaldpeetersite is named for Mau-rice Oswald Peeters, a structural crystallographer andresearcher at the University of Leuven, Belgium.

For more information:

Hawthorne, F.C., Schindler, M., Grice, J.D., and Haynes, P.,2001, Orthominasragrite, V4+O(SO4)(H7O)5, a new mineralspecies from the Temple Mountain, Emery County, Utah,U.S.A.: The Canadian Mineralogist, v. 39, p. 1325-1331.

Vochten, R., Deliens, M., and Medenbach, O., 2001,Oswaldpeetersite, (UO2)2CO3(OH)2 · 4H2O, a new basicuranyl carbonate mineral from the Jomac uranium mine,San Juan County, Utah, U.S.A.: The Canadian Mineralo-gist, v. 39, p. 1685-1689.

By Carl Ege

SU RV E Y NO T E S8

Editor’s note: Tom Chidsey, General Chairman for the 2003AAPG Annual Convention, is Manager of the Utah GeologicalSurvey’s oil and gas section. The Survey is an active AAPGsupporter and welcomes the 2003 AAPG Annual Convention toSalt Lake City.

Introduction"This is the right place!" proclaimed pioneer leaderBrigham Young as he entered the Salt Lake Valley in 1847.One hundred fifty-five years later, Salt Lake City is stillthe right place…the place to join 6,000 geologists fromaround the world for the Annual Convention of the Amer-ican Association of Petroleum Geologists (AAPG) and theSociety of Sedimentary Geology (SEPM). This meeting isscheduled for May 11-14, 2003, and is hosted by the UtahGeological Association (UGA).

The convention slogan and logo, “Energy—Our Monu-mental Task,” applies to the entire worldwide membershipof AAPG. The backdrop depicts the famous MonumentValley, located in Arizona and Utah, which represents theneed to balance preservation of the scenic open spaces ofthe American West with providing energy for a growingworld economy. Utah assists with this monumental taskof providing energy in an environmentally responsibleway while consistently remaining in the top 15 oil- andgas-producing states.

Technical ProgramFifty oral sessions and 50 poster sessions will provideapproximately 1,000 technical presentations during thethree-day conference. The session topics are grouped intonine themes: (1) global energy resources, (2) the businessside of petroleum, (3) technologies – new and proven, (4)reservoirs, (5) structure and tectonics, (6) stratigraphy, sed-imentology, and paleontology, (7) petroleum systems andgeochemistry, (8) environmental issues, and (9) studentpresentations. Sessions sponsored by AAPG and SEPMwill cover a wide range of hot topics including new playconcepts from the world’s petroleum provinces, deep-water sequence stratigraphy and deposition, biostratigra-phy, reservoir modeling, salt tectonics, lacustrine reser-voirs, and emerging gas plays. Each of the AAPG divi-

sions - Energy Minerals Division (EMD), Division of Envi-ronmental Geosciences (DEG), and Division of Profession-al Affairs (DPA) - is sponsoring specific sessions andforums on topics such as coalbed methane, carbon dioxidesequestration, remote sensing, methane hydrates, environ-mental best practices, and national security as it pertainsto petroleum.

Field Trips“The landscape everywhere . . . is of rock - cliffs of rock,tables of rock, plateaus of rock, terraces of rock, crags ofrock - ten thousand strangely carved forms; rocks every-where,” was penned by Major John Wesley Powell on July17, 1869, to describe what is now part of CanyonlandsNational Park. The rest of Utah also has rocks every-where. The 23 field trips being offered at the Salt LakeCity meeting will provide ample opportunity to witnessspectacular displays of well-exposed geology.

The field trips will take participants to the classic Utahgeology that serves so well as both modern and ancientoutcrop reservoir analogs. These trips fit into the widerange of convention themes where participants can exam-ine ancient and modern lake deposits, thrust and exten-sional faulting, salt tectonics, fluvial-deltaic sequences,

Energy NewsEnergy News

Salt Lake City to Again Host the AAPG Annual Convention in 2003

by Tom Chidsey

Convention field trips will include classic geologic sites throughoutUtah, such as Dead Horse Point. Photo courtesy of Utah Division ofParks and Recreation.

Continued on page 13...

SU RV E Y NO T E S 9

Patches of snow sometimes persistthroughout most, if not all, of the yearin Utah’s areas of high elevation, suchas on the east side of Mt. Timpanogosin Utah County. These patches ofsnow, often called snowfields, are notglaciers. Although we may currentlybe living in a time period called an iceage (albeit a warm interval within thistime period)*, the glaciers in Utah dis-

appeared thousands of years ago.

A glacier is a moving mass of ice andsnow. When enough snow layersaccumulate, the lower layers compactand recrystallize into ice. The heavymass then slowly moves downslopeby the force of gravity. The thick (forexample, over 1,000 feet thick in someof Utah’s mountain ranges) mass per-sists from year to year.

Snowfields, in contrast, do not move.Typically, the snow is not very deepeither (for example, only several feetthick on parts of the Mt. Timpanogos

snowfield). Sometimes, the snowmay even completely melt out duringthe peak of high summer tempera-tures.

Glaciers have covered mountainranges and high plateaus in Utah atvarious times in the past; the mostrecent glacial episode was approxi-mately 30,000 to 10,000 years ago. Atthat time, the climate was colder (howmuch colder is up for debate, butsome estimates are as much as 45° to60°F colder) and wetter (again, up fordebate, but possibly as much as 33percent more precipitation). Greatdepths of snow accumulated, espe-cially in basins over 10,000 feet in ele-vation, where glaciers would form.These great masses of ice eventuallyextended downslope to elevations aslow as 5,000 feet in some areas.

?? ??? ?? ?by Sandy Eldredge

??“Glad You Asked”“Glad You Asked” Are there glaciers inUtah’s mountains?

Mt. Timpanogos snowfield on the east side ofthe mountain. Note the thin patches of snow.

Glacier on Kenai Peninsula, Alaska, showsthe thick mass of ice and snow, which calvesoff (breaks and falls) into the ocean as it con-stantly moves downslope.

Glaciated areas in Utah included the moun-tain ranges and plateaus shown on this map.The Uinta Mountains claim the largest icecoverage at about 1,000 square miles, withsome glaciers as long as 27 miles. TheWasatch Range was the next-largest glaciatedarea with over 60 glaciers, some descending aslow as 5,000 feet in elevation. Another majorglaciated area was over 50 square miles on theAquarius Plateau. Glaciers retreated andadvanced in response to climate fluctuations.The most recent warming trend caused thelast glaciers to melt out of Utah’s uppermostreaches about 8,000 to 7,000 years ago.

*An ice age is a long time interval(millions to tens of millions of years)when air temperatures are relativelycold and large areas of the Earth arecovered by glaciers, both in the moun-tains (alpine or valley glaciers) andover continents (continental glaciers).The current ice age began between 2and 3 million years ago. Because airtemperatures fluctuate over the mil-lions of years of an ice age, there arerelatively colder times (glacial peri-ods) and relatively warmer times(interglacial periods). Therefore, gla-ciers go through various stages ofadvancing and retreating and/orappearing and disappearing. Themost recent glacial period probablypeaked about 18,000 to 20,000 yearsago. The climate has continued tomore or less warm ever since, and weare probably now in a warm (inter-glacial) period within this ice age.

SU RV E Y NO T E S10

GeoSights

It’s early September 2002 at Rozel Point in Gunnison Bay(the north arm) of Great Salt Lake about 16 miles (24 km)from the Golden Spike National Historic Site. A spiralform of salt-encrusted basalt boulders is just emergingfrom the pinkish water. Seldom-seen Spiral Jetty is visibleagain!

Artist Robert Smithson created Spiral Jetty in April 1970and later donated the earthwork art to the Dia Center forthe Arts in New York. Great Salt Lake’s setting and theartistic contrast between the pink water, white salt crys-tals, and black basalt boulders evidently inspired Smith-son. But perhaps the most intriguing aspect of Smithson’screation, which is 1,500 feet (457 m) long and 15 feet (4.6m) wide, is that it is only visible when climate conditionscause the level of Great Salt Lake to drop below an eleva-tion of 4,197.8 feet (1,280.2 m).

The water’s pink color is due to a red pigment in the salt-tolerant bacteria and algae that survive in the north arm’sextreme 27 percent salinity. Great Salt Lake was split intotwo parts by a rock causeway constructed across the lakeby the Southern Pacific Railroad in 1959. Before the cause-way was built, fresh water from the Bear, Weber/Ogden,and Jordan Rivers circulated throughout the entire GreatSalt Lake. When the causeway was built, circulationbecame restricted and salt content of the north armincreased because most of the river water flows intoGilbert Bay (the south arm).

White salt crystals encrust almost any solid object in con-tact with north-arm water. The black basalt bouldersSmithson took from the beach to construct Spiral Jetty areno exception; they are now covered with salt crystals. Thebasalt boulders are from local volcanic eruptions duringPliocene time, about 5 to 2 million years ago.

Spiral Jetty surfaced several times between 1970 and 2002.Throughout the lake-level fluctuations Spiral Jetty sur-vived wave erosion; the hard salt crust probably cementedthe boulders together and provided a protective layer onthe jetty surface.

GeoSightsPink Water, White Salt Crystals, Black Boulders,

and the Return of Spiral Jetty!by William F. Case

Aerial view of Spiral Jetty showing pink salt water and black basalt boul-ders draped with a crust of white salt crystals. Lake level is 4197.3 ft.Copyright, Francisco Kjolseth, Salt Lake Tribune, August 28, 2002.

Location map for the Spiral Jetty.

SU RV E Y NO T E S 11

How to Get ThereDrive to the Golden Spike National Historic Site (GSNHS),30 miles (45 km) west of Brigham City, Utah by followingsigns on Utah State Route 83 through Corinne. Once atGSNHS take the gravel road leading west toward the WestSide Drive approximately 6 miles (9 km) to an intersectionthat has a small white “Promontory Ranch” sign. Take thesouth (left) road from the “Promontory Ranch” sign inter-

section and continue south about 1 mile (1.5 km) to anintersection near a corral; veer right to the road that headssouthwest and continue about 9 miles (13.5 km) to GreatSalt Lake at Rozel Point. You will see an old, white,mobile home and rusted military amphibious vehicle, alinear jetty associated with past oilfield activity, and, if thewater is low enough, the Spiral Jetty. A map and instruc-tions are at www.nps.gov/gosp/tour/jetty_directions.htm.

Spiral Jetty, September 15, 2002; lake level is 4197.2 ft. Copyright2002, Bruce Thompson/Pingraphics, used by permission.

White salt encrusting black basalt boulders on the shore of Great SaltLake near Spiral Jetty, September 14, 2002, lake level 4197.2 ft.

On Sunday, November 3, 2002, at 3:12p.m. (MST), a large (magnitude 7.9)earthquake occurred on the Denalifault in Alaska. Coincident with thearrival of the seismic waves in Utaharound 3:28 p.m., the University ofUtah's regional seismic networkdetected a marked increase in earth-quake activity along the Intermoun-tain seismic belt in Utah. The earth-quakes were small-magnitude events(less than magnitude 3.3) generallyconcentrated in five clusters. With theexception of a cluster northeast ofNephi (cluster C in figure below), theevents occurred in localities withrepetitive prior seismicity. The firstlocatable triggered earthquake was a

magnitude 2.6 shock about 12.5 mileseast of Salt Lake City. It occurred alittle before 3:30 p.m. In the 12 daysfollowing the Denali fault earthquake,the mean rate of earthquakes abovemagnitude 1.5 in the Wasatch Frontarea increased to almost triple themean rate for the previous threeyears. Statistically it can be shownthat this rate increase was not due tochance.

The first well-documented case of alarge earthquake triggering small dis-tant earthquakes was the 1992 magni-tude 7.3 Landers, California earth-quake. The Landers earthquake trig-gered small earthquakes up to 775

miles from the source. Researchersobserved that the triggered earth-quakes occurred (a) in the direction ofearthquake rupture, (b) in areaswhere the seismic waves temporarilyenhanced the stress field and (c) most-ly in areas of recent volcanic or geo-thermal activity. Observations (a) and(b) similarly apply to the earthquaketriggering in Utah, but not observa-tion (c) (see below). The Denali faultearthquake ruptured in an east-south-eastward direction along the Denalifault, and Utah is along a projectionof this rupture direction (see figure).Using data from 44 recording sites inUtah, including 38 new strong-motionstations of the Advanced National

TTriggered Seismicity in Utah from the riggered Seismicity in Utah from the November 3, 2002 Denali Fault EarthquakeNovember 3, 2002 Denali Fault Earthquake

by K.L. Pankow, W.J. Arabasz, S.J. Nava, and J.C. PechmannUniversity of Utah Seismograph Stations

Seismic System and six broadband stations,we estimate that the temporary increase in thestress field was approximately 100 timesgreater than the daily stress variation associat-ed with solid earth tides.

What makes the observation of triggeredearthquakes in Utah distinct from earlierobservations is the geologic setting and thelarge distance (more than 1,850 miles) fromthe Denali fault earthquake. Remotely trig-gered earthquakes in the past have beenobserved chiefly in regions characterized byrecent volcanic or geothermal activity, such asYellowstone National Park in Wyoming, TheGeysers in northern California, and Long Val-ley caldera in eastern California. Further,many of the mechanisms proposed to generatethe triggered earthquakes attribute the earth-quakes to effects on fluids associated withrecent volcanic or geothermal activity. Theregions of earthquakes in Utah triggered bythe Denali fault earthquake fall into neither ofthese two categories. By systematically study-ing these earthquakes, we hope to providenew clues into the dynamic triggering of dis-tant earthquakes. For more information, go tohttp://www.seis.utah.edu/AGU2002/index.shtml.

SU RV E Y NO T E S12

-114o -113o -112o -111o -110o -109o

37o

38o

39o

40o

41o

42o

0 50 100

km

UTAH EARTHQUAKESOctober 23 ,2002 − November 3 (22:39), 2002

-114o -113o -112o -111o -110o -109o

37o

38o

39o

40o

41o

42o

0 50 100

km

UTAH EARTHQUAKESNovember 3 (22:39), 2002 − November 15, 2002

A

B

C

D

E

Wasatch Front Sample Area

12 Days After DFE

12 Days Before DFE

131 events20 events

MAGNITUDES

0.0+

1.0+

2.0+

3.0+

Comparison of earthquake activity in Utah immediately before and after the Denali fault earthquake (A-E represent clusters of earthquakes). Datafrom the University of Utah seismic network.

Projection showing Utah in relation to the rupture direction (solid line; dashed line±10°) of the Denali fault earthquake (indicated by star).

SU RV E Y NO T E S 13

Saturday, May 10, 2003, teachers may choose one of twofield trips.

(1) Geology along the Wasatch Front 8:00 a.m. – 4:00p.m.

Teachers will learn about the local geology and geo-logic processes that have made today’s landscape,and will see the three different rock types. Limit 40teachers.Lunch and transportation provided.$10.00

(2) Antelope Island and Great Salt Lake, Utah: A natu-ral history view of Utah’s un-dead sea and its biggestisland 8:00 a.m. - 4:00 p.m.

Teachers will learn about local geologic history fromAntelope Island. Other topics include the dynamicsof Great Salt Lake and Lake Bonneville. Limit 20teachers.Lunch and transportation provided.$10.00

Saturday, May 17, 2003 8:30 a.m. - 4:00 p.m.

More! Rocks in Your Head, a nationally acclaimedworkshop, will be offered to Utah teachers. The work-shop covers core curriculum topics of rocks, minerals,fossils, and soil (4th); weathering and erosion (4th &5th); geologic processes affecting Earth’s surface (5th);and deposition of rock layers (5th). Teachers are guar-anteed to walk away excited to share what they’velearned with their students. All activities are hands-onand require little or no teacher preparation time. Teach-ers will receive:

- manual- rock and mineral kit- classroom-ready materials

Location: Department of Natural Resources1594 W. North TempleSalt Lake City, UT

Snacks and lunch provided$10.00

Teacher’s CornerTeacher’s CornerGEOLO

GY

Attention 4th- and 5th-grade teachersField trips and workshop offered May 10 and May 17, 2003

1 Hour Inservice CreditOnly $20.00

These greatly reduced prices for teachers are due to the generous sponsorship by the American Association of Petro-leum Geologists (AAPG) and ConocoPhillips. The AAPG national convention will be held in Salt Lake City theweek of May 12, 2003.

Register early! Registration deadline is April 1, 2003.For One Hour Inservice Credit, you must sign up for both a field trip and the workshop. Or just attend one Saturday tofurther your earth science understanding! For further information, please contact Sandy Eldredge at 537-3325,sandyeldredge@utah.gov or visit the Utah State Office of Education’s website http://www.usoe.k12.ut.us/curr/science/.

carbonate mounds, eolian facies,dinosaur fossils, the geology of coaland coalbed methane, and sequencestratigraphy. Many of these trips willtake place in national parks, monu-ments, and recreation areas, such asZion, Arches, Canyonlands, LakePowell, and the Grand Canyon, thatwere set aside for their geology andscenic beauty.

Short CoursesA variety of short courses (19) arebeing planned by the AAPG, its affili-ated divisions, the SEPM, and theUGA. The short courses will empha-size the application of advanced tech-nology to more efficiently find anddevelop oil and gas resources in the21st Century. Topics includeadvanced risk analysis, coalbedmethane, petroleum systems analysis,

applied sequence stratigraphy, andthe analysis and interpretation of sub-surface pressures, as well as a Para-dox Basin core workshop (sponsoredby the Utah Geological Survey andthe U.S. Department of Energy).

Note: One does not have to register forthe convention to attend a field trip orshort course. For more information con-tact the AAPG Convention Departmentat 1-800-364-2274.

...Continued from page 8

Utah Geological Survey1594 W. North Temple, Suite 3110Box 146100Salt Lake City, UT 84114-6100Address service requestedSurvey Notes

PRSRT STDU.S. Postage

PAIDSalt Lake City, UTPermit No. 4728

Geologic map of the Tule Valley 30’ x 60’ quadrangle and partsof the Ely, Fish Springs, and Kern Mountains 30’ x 60’quadrangles, northwest Millard County, Utah, by L.F.Hintze and F.D. Davis, 2 pl., 1:100,000, ISBN 1-55791-586-5,Map 186 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $8.90

Geologic map of the Manti 7.5-minutequadrangle, Sanpete County, Utah byMalcolm P. Weiss and Douglas A.Sprinkel, 22 p., 2 pl., 1:24,000, ISBN 1-55791-588-1, 11/02, M-188 . . . . . $9.45

Ground-water sensitivity and vulnerabilityto pesticides, Utah and Goshen Val-leys, Utah County, Utah, by Ivan D.Sanderson, Mike Lowe, Janae Wallace,and Jason L. Kneedy, 26 p., 2 pl., scale1:100,000, 10/02, ISBN 1-55791-678-0, MP-02-10 . . . . $12.45

Witkind, I.J., and Weiss, M.P., 1991 (digitized2002), Geologic map of the Nephi 30' x60' quadrangle, Carbon, Emery, Juab,Sanpete, Utah and Wasatch Counties,Utah, scale 1:100,000 (digitized from U.S.Geological Survey Miscellaneous Investi-gations Map I-1937): CD-ROM, 11/02,ISBN 1-55791-589-X, Map 189DM . . . . . . . . . . . . . . . . .$24.95

St. George dinosaur tracksite, 2 p., 9/02, PI-78 . . . . . . . . . . . free

Interim geologic map of the San Rafael Desert 30' x 60' quad-rangle, Emery and Grand Counties, Utah, by Hellmut H.Doelling, 1 pl., 20 p., 1:100,000, 10/02, OFR-404 . . . . . $6.50

October 2002 Publications list (paper and on CD)

Central Utah coal fields: Sevier-Sanpete,Wasatch Plateau, Book Cliffs and Emery,by Hellmut H. Doelling, 1972 (reprint,2002, CD-ROM), 333 p., ISBN 1-55791-682-9, MO-3 . . . . . . . . . . . . . . . . . $14.95

Interim geologic map of the Cedar Fort quadran-gle, Utah County, Utah, by Robert F. Biek, 16 p., 1 pl.,1:24,000, 10/02, OFR-403 . . . . . . . . . . . . . . . . . . . . . . . . . $3.00

The geology of Cedar Valley, Iron County,Utah, and its relation to ground-waterconditions, by Hugh A. Hurlow, 74 p.,2 pl., 1:100,000, 9/02, ISBN 1-55791-672-1, SS-103. . . . . . . . . . . . . . . . $22.50

Interim geologic map of the SaratogaSprings quadrangle, Utah County,Utah, by Robert F. Biek, 16 p., 1 pl.,1:24,000, 10/02, OFR-402 . . . . . $3.00

Interim geologic map of the Veyo quadrangle, WashingtonCounty, Utah, by Janice M. Higgins, 17 p., 1 pl., 1:24,000,10/02, OFR-401 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $3.00

Coal Studies: reprints of Bulletin 112, Special Study 49, andSpecial Study 54 on CD, 6 papers, 236 p., 7 pl. . . . . . .$14.95

Rainbow of rocks, mysteries of sandstonecolors and concretions in ColoradoPlateau canyon country, by MarjorieA. Chan and William T. Parry, 17 p.,10/02, ISBN 1-55791-681-0,PI-77 . . . . . . . . . . . . . . . . . . . . . . . $2.00

New Publications

Available for free while supply lasts. Two CDs of U.S.Department of Energy’s oil fluvial-dominated and shallow-shelf carbonate recovery studies. 22 papers total, includingUGS’s Uinta and Paradox Basin studies.

Natural Resources Map & Bookstore1594 West North Temple, Salt Lake City, UT

801-537-3320 or 1-888-UTAHMAP (1-888-882-4627) • http://mapstore.utah.gov