survey notes: may 2012

7/31/2019 Survey Notes: May 2012

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

SURVEY NOTESMay 2012Volume 44, Number 2

DIGGING UP INFORMATIONON EARTHQUAKE SOURCES

IN SALT LAKE VALLEY


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his issue of Survey Notes highlights some ofhe geologic hazards that Utahns live withinarticular earthquakes and landslides. Lookingack over the past year, the UGS published eightapers and reports on a variety of geologic-azard events, and UGS authors submitted 17bstracts on similar topics to conferences androfessional societies. One report that has justeen published investigates a type of hazardhat has been subtly occurring in parts of Utahor decades but in recent years has had a greatermpact on property, namely ground subsidenceue to a declining groundwater level. Thiseport, by Richard Forster (University of Utah),valuated what is called the InSAR techniqueor measuring the subsidence in Escalante

Valley between 1998 and 2006 (UGS Open-FileReport 589, 2012). The technique uses satel-

te radar imagery of the ground surface, andy overlaying images generated at different

mes an interference pattern (interferogram)s created that indicates changes in ground

elevation. InSAR is capable of detecting changesin elevation as small as fractions of an inchin areas where there has not been signiicantground disturbance (such as from plowing),or where crop growth or snow accumulationhas not obscured the ground surface at differ-

ent times of the year. An especially powerfulaspect of InSAR is that interferograms can beretrospectively compiled from radar imagescollected as far back as the early 1990s whenthe irst radar satellites were launched.

Open-File Report 589 shows that the subsid-ence rates in Escalante Valley between 1998and 2006 ranged to over 2 inches per year. Inthe main area of irrigated cropland there waspoor coherence and subsidence rates could notbe determined. The report also shows that thearea of subsidence increased in extent and therate of subsidence accelerated by about 1/8inch per year between the late 1990s and 2006.The total maximum subsidence since the late

1990s has been over 2 feet. The rate of ground-water-level decline due to withdrawal in theBeryl Junction area of Escalante Valley has beenaround 2 feet per year since the 1950s, and thetotal decline is now more than 100 feet in somewells. In January 2005, a warm winter storm ontop of a melting snowpack caused a large loodwhich enlarged previously unnoticed groundissures in the valley. One issure cut across andbriely closed the main road near Beryl Junction(SR-56), and issures occurred discontinuouslyover a total distance of 5.6 miles. A UGS reportdocumenting the effects and investigating thecauses found some issures were over 10 feetdeep, over 6 feet wide, and over 1000 feet long(Special Study 115; Lund and others, 2005).

The report concluded that groundwater with-drawal was causing permanent compaction of

ine-grained deposits at depth, and that wa lateral gradient exists in the thickness omore compressible deposits, issures cform at the surface. This phenomenon hasoccurred in Arizona and Nevada, where ialso been attributed to groundwater decli

The UGS has recently been studying issand subsidence in Cedar Valley, west of CCity, at the request of the Central Iron CoWater Conservancy District. This studytriggered by the occurrence of issuresdisrupted roadway pavement and curbsreversed the grade of sewage lines in asubdivision under construction near EnOur groundwater scientists have been wowith our Cedar City-based hazards geoloto characterize the hydrogeologic charaistics beneath the valley, water withdrpatterns and water-level changes with and issure patterns and evidence for the e

of subsidence. An InSAR survey has revealong history of subsidence over much of CValley, with local centers near Enoch innorth and Quichapa Lake in the south. work adds to the results from an earlier Instudy commissioned by the UGS in 2006found evidence for subsidence in EscalParowan, and Milford valleys. These vahave all seen several decades of signiwater-level declines. With ongoing grounter-level declines in many valleys of soutUtah, ground subsidence is another hazardsome Utahns will have to adapt to. In conto many geologic hazards, subsidence dugroundwater extraction is human-indand can be controlled to some extent thrprudent land-use and water-use decisions

Design: Stevie EmersonCover: Eastward view of research trench across

a small (about 3 feet high) fault scarp onthe West Valley fault zone in Salt LakeValley. Photo by Michael Hylland.

The DirectorsPerspective

by Richard G. Allis

CONTENTSEvaluating the seismic relation between the

West Valley fault zone and Salt Lake Citysegment of the Wasatch fault zone ............1

Another large landslide closes highway nearCedar City, Utah .........................................4

2011 Landslides in Utah ..................................6Energy News ....................................................8GeoSights ...................................................... 10

Glad You Asked ...............................................11Teachers Corner .............................................12Survey News ...................................................12New Publications ............................................13

StateofUtahGary R. Herbert, Governor

DepartmentofNaturalResourcesMichael Styler, Executive Director

UGSBoardWilliam Loughlin, ChairJack Hamilton,Tom Tripp,Sunny Dent, Mark Bunnell,Kenneth Puchlik, Mark Eckels,Kevin Carter (Trust LandsAdministration-ex ofcio)

UGSStaff

AdministrationRichard G. Allis, DirectorKimm Harty, Deputy DirectorJohn Kingsley,Associate DirectorStarr Losee, Secretary/ReceptionistDianne Davis,Administrative SecretaryKathi Galusha,Accounting OfcerLinda Bennett, Accounting TechnicianMichael Hylland, Technical ReviewerRobert Ressetar, Technical Reviewer

EditorialStaffVicky ClarkeLori Steadman, Stevie Emerson,Jeremy Gleason, Jay Hill

GeologicHazardsSteve BowmanRichard Giraud, William Lund,Greg McDonald, Jessica Castleton,Gregg Beukelman, Chris DuRoss,Tyler Knudsen, Corey Unger,Adam McKean, Ben Erickson,Pam Perri, Amanda Hintz

GeologicInformationandOutreach

Sandra EldredgeChristine Wilkerson, Patricia Stokes,Mark Milligan, Stephanie Earls,Emily Chapman, Lance Weaver,Gentry Hammerschmid, Jim Davis,Marshall Robinson, Randi Ryan

GeologicMappingGrant WillisJon King, Douglas Sprinkel,Janice Hayden, J. Buck Ehler,Kent Brown, Basia Matyjasik,Don Clark, Bob Biek, Paul Kuehne

EnergyandMineralsDavid TRobert Blackett, Craig MoMike Laine, Jeff Quick,Taylor Boden, Thomas ChCheryl Gustin, Tom DempBrigitte Hucka, Stephanie Ken Krahulec, Brad WolveSonja Heuscher, Mike VanBerg, Andrew Rupke, MarChristian Hardwick, Peter

GroundwaterandPaleontolo

Michael LoweJames Kirkland, Janae WaMartha Hayden, Hugh HDon DeBlieux, Kim Nay,Paul Inkenbrandt, Lucy JoKevin Thomas, Rebecca MWalid Sabbah, Rich EmerStefan Kirby, Scott MadseGary Hunt

Survey Notes is published three times yearly by Utah Geological Survey, 1594 W. North Temple, Suite 3110, Salt Lake City, Utah 84116; (801) 537-3300. The Utah Geological Survey provides time

scientic information about Utahs geologic environment, resources, and hazards. The UGS is a division of the Department of Natural Resources. Single copies ofSurvey Notes are distributed freecharge within the United States and reproduction is encouraged with recognition of source. Copies are available at geology.utah.gov/surveynotes. ISSN 1061-7930


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EVALUATING THE SEISMIC RELATIONBETWEEN THE WEST VALLEY FAULT ZONE ANDSALT LAKE CITY SEGMENT OF THE WASATCHFAULT ZONE, SALT LAKE VALLEY, UTAHMichael D. Hylland, Christopher B. DuRoss, and Greg N. McDonald

Background

The Wasatch fault zone has long been known to be a seriousearthquake threat to the Wasatch Front region. In Salt Lake Valley,strands of the Salt Lake City segment of the fault zone pass directlythrough Utahs capital city. However, another possible source oflarge (approximately magnitude [M] 6.5) earthquakes lies just afew miles west of Salt Lake Citythe West Valley fault zone, com-prising a system of faults on the floor of northern Salt Lake Valley.Like the Wasatch fault zone, the West Valley fault zone shows evi-dence of recurrent movement in the geologically recent past (i.e.,the past 10,000 years). But unlike the Wasatch fault zone, which

has been the subject of dozens of detailed scientific studies, relatively little is known about the behavior of the West Valley faultzone.

The Utah Geological Survey (UGS) recently conducted paleoseismic (fault trenching) studies of large, prehistoric earthquakes onthe West Valley fault zone (Baileys Lake site; September 2010) andSalt Lake City segment (Penrose Drive site; May 2010). In addition to UGS geologists, the investigative team included geologistswith the U.S. Geological Survey, URS Corporation, and KansasState University. The new data collected during these detailedstudies will allow us to better characterize earthquake activity onboth fault zones. We can then compare the timing of past earthquakes on the two fault zonesan important step in improvingour understanding of how the fault zones interact and what kind

of earthquake activity to expect in the future.

The West Valley fault zone is antithetic to the Salt Lake City segment; that is, the fault plane of the Salt Lake City segment slopeswestward beneath Salt Lake Valley, whereas the fault plane ofthe West Valley fault zone slopes eastward, toward the Salt LakeCity segment. Important questions pertain to the seismic relationbetween the two fault zones: When the Salt Lake City segmentmoves and generates a large earthquake, does the West Valleyfault zone also move at the same time? Or can the West Valleyfault zone move independently of the Salt Lake City segment, andtherefore need to be considered a separate source of large earthquakes? The answers to these questions have significant implications for the seismic hazard of the greater Salt Lake City metro-politan area.

e West Valley fault zone comprises two strands: the Granger andylorsville faults. The Salt Lake City segment, one of the central, mostve segments of the Wasatch fault zone, comprises three strands:

Warm Springs, East Bench, and Coonwood faults. In 2010, theS conducted fault trenching studies at the Penrose Drive andleys Lake sites.

Our trenches at the Penrose Drive site exposed geologic evidence for six large earthquakes on the East Bench fault in the past 17,000 year

near-vercal fault plane (indicated by arrows) separates lighter-calluvial-fan deposits from darker-colored slope deposits includin

ll, and sediments eroded from the fault scarp (scarp-derived colluHorizontal string grid lines are spaced 1 meter (3.2 feet)

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Summary of Results

At the Penrose Drive site, immediatelynorth of the University of Utah campus,fault movement on the East Bench faultof the Salt Lake City segment has cre-ated a steep scarp about 30 feet high. Weexcavated two trenches across the scarpand exposed geologic deposits as old as60,00070,000 years, including depos-its resulting from surface faulting datingback to about 17,000 years ago when thesite was along the Provo shoreline of latePleistocene-age Lake Bonneville. Geologicevidence indicates five or perhaps six post-Provo earthquakes, each one displacingthe ground surface vertically by about 3 to

6 feet. The older (pre-Bonneville) alluvial-fan deposits have been displaced verticallyby at least 52 feet.

At the Baileys Lake site, immediately westof Salt Lake City International Airport,movement on the Granger fault of theWest Valley fault zone has created twoparallel scarps 1 to 3 feet high. We exca-vated a total of three trenches across thescarps and exposed geologic deposits asold as about 35,000 years, including evi-dence of fault movement dating back toabout 15,000 years ago when the site was

deeply submerged beneath the waters of

Lake Bonneville. Geologic evidence indi-cates four or perhaps five post-Bonneville-highstand earthquakes, each one displac-ing the ground surface vertically by about1.5 feet and resulting in about 6 feet ofvertical displacement of the pre-highstandLake Bonneville deposits.

Determining the timing of prehistoricearthquakes involves dating geologic

deposits that are closely associated with

fault movement. Two methods that wehave found most useful are radiocarbondating, which measures concentrationsof the radioactive isotope carbon-14, andoptically stimulated luminescence (OSL)

Vercal movement on the west-dipping Wasatch fault zone hascreated the Wasatch Range in the uplied crustal block andSalt Lake Valley in the adjacent downdropped crustal block.The West Valley fault zone is an anthec system of faultsin the Salt Lake Valley block, dipping eastward towardthe Wasatch fault zone. (Mapped fault traces from theQuaternary Fault and Fold Database of the UnitedStates, superimposed on a Google Earth image.)

Log of the east trench at the Penrose Drive site shows faulted alluvial-fan deposits on the upthrown (right) side of the fault, and stacked deposits ofscarp-derived colluvium on the downthrown (le) side of the fault. Colluvial units P1 through P5 provide evidence for ve or six large earthquakesthat occurred aer Lake Bonneville retreated from this site around 14,500 years ago, and P6 is stragraphic evidence for an earthquake during theme that the lakes Provo shoreline was at or near this site. Grid-line spacing is 2 meters (6.4 feet).

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(continued on page 7)

Log of one of the trenches at the Baileys Lakshows mostly ne-grained sediments depo

during the rise and fall of Lake Bonneville in th

Pleistocene and the much smaller Gilbert lakeat the end of the Pleistocene, plus Holocene delargely consisng of wind-blown silt and clay (loFault movement has displaced the strata down

on the east (le) side of the sheared fault Turbidites (thin layers of silt and sand) interbe

within Lake Bonneville clays represent epinuxes of sediment associated with disturb

around the margins of the lake, possibly causlake-level uctuaons or perhaps earthqu

Grid-line spacing is 1 meter (3.2

trenches at the Baileys Lake site exposed geologic evidence for four or ve large earthquakes

he Granger fault in the past 15,000 years. Layers of Lake Bonneville sediment have beened and displaced downward on the le (east) side of the steeply dipping fault plane alongch the geologist is placing red markers. String grid-line spacing is 1 meter (3.2 feet).

which measures the effects of trapped elec-trons that accumulate over time in the min-eral grains of buried sediment. We analyze ourdating results in a computer program that usesthe geologic deposit ages to mathematicallymodel the timing of fault movement. Althoughthis is a rigorous process, the resulting earthquake times typically have uncertainties of hun-dreds of years, so comparing earthquake timeson different fault zones is somewhat problematic. Still, our results for this study show close

similarities in the timing of West Valley faultzone and Salt Lake City segment earthquakesand suggest that West Valley fault zone earth-quakes likely occur in response to earthquakeson the Salt Lake City segment.

Ongoing Work

We cannot presently determine whether WestValley fault zone earthquakes occur coseismically (nearly instantaneously) with Salt LakeCity segment earthquakes, or are triggered bythem, occurring as aftershocks hours to perhapsmonths later. To help answer this question, weare looking at historical analogs of antithetic

faulting from elsewhere in the world, including the 1984 Devil Canyon earthquake (M 5.8in Idaho, 1980 CampaniaBasilicata earthquake

3 m

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At approximately 5:00 a.m. on Saturday,October 8, 2011, a large landslidedetached from the south side of CedarCanyon about 8 miles east of CedarCity, Utah. The landslide quickly moveddownslope, displacing part of andburying the remainder of an approxi-mately 1200-foot-long section of UtahState Route 14 (SR-14), an importanttransportation link between Interstate15 at Cedar City and U.S. Highway 89 tothe east. The landslide then continuedto the bottom of Cedar Canyon whereit partially blocked Coal Creek, causinga series of small ponds to form beforethe stream re-established its low path.The landslide was approximately 1000feet long, up to 1700 feet wide, and anestimated 5075 feet thick. The UtahDepartment of Transportation (UDOT)estimates the landslide volume at about4 million cubic yards. Fortunately, nomotorists were on the affected section ofSR-14 when the landslide occurred.

Cedar Canyon incises the western margin

of the Markagunt Plateau at the transi-tion between the Basin and Range andColorado Plateau physiographic prov-inces. Deformed Mesozoic sedimentarystrata in the transition zone are exposedin the lower several miles of the canyon;however, at the landslide, the canyon isin the Colorado Plateau proper, and rockunits are largely undeformed, dippinga few degrees to the east. The strati-graphic section at the landslide includes

the cliff-forming Tibbet Canyon Memberof the Straight Cliffs Formation, and theunderlying slope-forming Tropic Shaleand Dakota Formation, all Cretaceous inage. The 600-foot-thick Tibbet CanyonMember is chiely ine- to coarse-grained, limey sandstone; the 30-foot-thick Tropic Shale is sandy mudstoneand muddy sandstone; and the greaterthan 600-foot-thick Dakota Formation ischiely interbedded mudstone and sandymudstone with thin sandstone beds andcoal horizons up to several feet thick.

About a half mile west of the land-slide, SR-14 leaves the bottom of CedarCanyon and begins climbing the steep,south canyon wall toward the top of theMarkagunt Plateau. The Tropic Shaleand Dakota Formation are exposed inthe lower part of the canyon wall andare susceptible to landsliding. Publishedreports of landslides along this sectionof SR-14 go back to at least 1949, anda similar large landslide (estimatedvolume 2 million cubic yards) just west

of the current slide closed SR-14 forseveral months in 1989. In 2009, a largerock fall (estimated volume 60,000 cubicyards) detached from the Tibbet CanyonMember cliff at this location and closedSR-14 for several days (see article inSurvey Notes, v. 41, no. 3, September2009). Most of the rock-fall material fellonto what is now the western lank of the2011 landslide. An examination at thattime showed no evidence of associated

landsliding either prior to or followingthe rock fall.

The present landslide is a complexdebris slide that originated at the baseof the Tibbet Canyon Member cliff inthe Tropic Shale and Dakota Formationportion of the stratigraphic sectionHowever, the extent to which the under-lying bedrock and pre-existing landslide

ANOTHER LARGE LANDSLIDE CLOSESHIGHWAY NEAR CEDAR CITY, UTAHWilliam R. Lund and Tyler R. KnudsenUtah Geological Survey

David FadlingUtah Department of Transportation

Landslide location along SR-14, 8 miles eas

of Cedar City, Utah.

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deposits are involved in the sliding isunclear. A thick section of colluvium and

talus had accumulated at the base of theTibbet Canyon Member cliff, and it is that

material that comprises the landslideat the surface. UDOT has undertaken a

geotechnical investigation to determinewhether bedrock or ancient landslide

deposits were involved in the failure,the depth and orientation of the failureplane, groundwater conditions in the

slide mass, and the extent to which thelandslide may have included a compo-

nent of rotational movement.

The immediate triggering mechanismfor the 2011 landslide was a rain andsnow storm that moved through thearea the previous day and evening. The

longer term cause is undoubtedly morecomplex, possibly involving loading from

the large 2009 rock-fall event, erosionof the slope toe by Coal Creek, and the

presence of several thousand feet ofabandoned coal-mine workings beneaththe landslide area, all combined with

a wetter-than-normal 201011 winterthat may have raised the groundwater

level and pore-water pressure in the

pre-failure landslide mass. At least threeabandoned coal mines are known tobe near the landslide, but the extent towhich underground workings may havecontributed to this and previous land-sliding at this location is unclear.

UDOT has completed the planning anddesign phases for a new roadway acrossthe landslide. Construction began inmid-March 2012, and a temporary roadacross the landslide is expected to beavailable for limited public use by earlysummer. UDOT hopes to fully reopen

SR-14 by July 4, 2012.

SR-14 buried by landslide debris at the west landslide boundary. SR-14 sheared and displaced downslope at the east landslide bounda

Significant historical landslides and rock falls that have affected SR-14 near milepost 8. View faces

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Richard Giraud and Tyler Knudsen

Above-normal precipitation during 2011 trig-gered landslide movement in many areasthroughout Utah, and the UGS Geologic Haz-ards Program assisted several local govern-ment agencies with emergency response for

landslide problems. Significant economic lossresulted where landslides damaged homes,underground utilities, highways, and roads.The 2011 landslides followed patterns of pre-vious landsliding during years with above-nor-mal precipitation. Many landslides were reac-tivations of preexisting landslides and manyhad moved previously during the wet years of198283, 199798, and 200405.

Mountain snowpacks in 2011 were 300 to400 percent of average in many areas. Many2011 snowpacks contained more water than1983 snowpacks, which melted rapidly andtriggered numerous landslides and producedwidespread flooding. Surprisingly, the 2011snowmelt triggered fewer landslides than the1983 snowmelt. In the Wasatch Range east ofFarmington, the 1983 snowmelt produced 57inches of water in 35 days in one rapid con-tinuous melt period. In contrast, the 2011

snowmelt produced 67 inches of water days during several melt periods. Cool stemperatures combined with multiple, sduration melt periods resulted in a longeslower release of melt water from the

snowpack compared to the rapid melt wrelease from the 1983 snowpack.

However, snowmelt from the record or record 2011 mountain snowpacks triggmany landslides throughout Utah that arible on 2011 statewide National AgricuImagery Program aerial photography tlater in the year. Many of these landslideshallow landslides that were triggered near the end of snowmelt, such as the slide that stripped trees from the mounside, closed a road, and partially blockecreek in Brownie Canyon, 17 miles northof Vernal. Some landslides started mbefore the overlying snowpack had meMovement of these landslides deformefractured the overlying snowpack.

In northern Utah, many landslides reactivaround the Snowbasin area. The upper pthe Bear Wallow landslide above State R(SR) 226 (Snowbasin Road) moved 11 inwhich is almost as much as the observeinches of combined movement from through 2010. The Green Pond landslide aged SR-226 and a culvert under the roadold Snowbasin Road, which is closed durinwinter, was severely damaged by several

2011 LANDSLIDES IN UTAH

Garden South landslide in St. George 11/09/11

Old Snowbasin Road 06/02/11

Between Park City and Heber City 04/13/11

Wasatch Plateau east of Ephraim 08/01/11

Woods Ranch area east of Cedar City 06/15/11

Location of 2011 areas of landsliding in Utah.

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Chris DuRoss has been a geologist with the UGSGeologic Hazards Program since 2004. He special-izes in studying geologic evidence of large, pre-historic earthquakes in Utah, and has completedseveral fault-trench investigations on the Wasatchfault zone. He is also part of a working group taskedwith assessing the probability of a future largeearthquake in the Wasatch Front region.

Greg McDonald has been a geologist with the UGSGeologic Hazards Program since 1998 and habeen involved with many of the UGS paleoseismic studies performed during that time. Greg haalso worked on a variety of other projects includinglandslide, debris-flow, and rock-fall investigationssurficial geologic mapping, earthquake groundshaking-related studies, and landslide inventorymapping on the Wasatch Plateau.

Mike Hylland has been a geologist with theUGS since 1994, and splits his time as a UGStechnical reviewer and Geologic Hazards Pro-gram researcher. Current projects includepaleoseismic studies, geologic mapping,involvement in various earthquake workinggroups, and management of Utahs databaseof active faults.

(M 6.9) in Italy, and 1954 Fairview Peak (M7.2) and Dixie Valley (M 6.8) earthquakesin Nevada. Additionally, we are evaluat-ing the possible role of antithetic faultingin the 1934 Hansel Valley earthquake (M6.6), Utahs largest historical earthquake.

Our recent studies of the West Valley faultzone and Salt Lake City segment are partof a broader effort to continually improveour understanding of Utahs earthquakehazards and risk. Ultimately, our goals are

to increase public awareness and under-standing of earthquake hazards, provideinformation used in building codes for thesafe and cost-effective design and con-struction of buildings and other structures,and contribute to the development ofpublic policies that lead to more effectiveearthquake-preparedness and emergency-response efforts in Utah.

Our study of the West Valley fault zoneand Salt Lake City segment was partially

funded by the National Earthquake Haz

ards Reduction Program. The study results

are currently available in a Final Technica

Report that can be obtained through the

U.S. Geological Surveys External Research

Support web page (http://earthquakeusgs.gov/research/external/reports

G10AP00068.pdf). The report will be more

formally released by the UGS as part of the

Paleoseismology of Utah series in the nea

future.

(continued from page 3)

A B O U T T H E A U T H O R S

ides, including one that completely destroyed the road. Many landslideslong SR-167 (Trappers Loop Road) also reactivated. South of Snowbasin

n Mountain Green several landslides reactivated, causing further damageo houses already damaged by landsliding. Landslides also ruptured a culi-ary water line and damaged subdivision roads in Mountain Green. All ofhese landslides involve the Norwood Tuff, a clay-rich geologic unit that is

widely recognized for producing landslides.

lsewhere in northern Utah, the Chalk Creek Narrows landslide east ofoalville reactivated and threatened to block the creek. The landslide

moved 3 to 6 feet into the creek, but high stream flows eroded the land-ide toe as it advanced and kept the landslide from damming the creek.

n North Salt Lake, another house was demolished on the Springhill Driveandslide due to distress from continued slow landslide movement. Land-ides were also active in the Sherwood Hills area of Provo.

Many landslides also occurred in southern Utah. The largest and mostmpressive landslide was the October 8 landslide that destroyed a sec-on of State Route 14 in Cedar Canyon east of Cedar City (see article in

his issue). Previous landslides in this area have also closed the highway.arther east up Cedar Canyon, landslides damaged several houses in the

Woods Ranch area. Movement in part of the Green Hollow landslide onedar Mountain southeast of Cedar City continued to damage property

within the Cedar Highlands subdivision. The Garden South landslide in

St. George has moved slowly for several years, and accelerated landmovement in 2011 further damaged condominium units, a motel, ataurant, parking lots, and a retaining wall.

Years with above-normal precipitation like 2011 continue to show Uvulnerability to landslides and the associated economic losses. Comnities that have developed areas on landslides continue to face difchallenges when landslides damage commercial buildings, housespublic infrastructure. The 2011 landslides provide important lessohow to manage active landslides, where to build safely, and how tofor landslide hazards. The UGS continues to map landslides, docuhistorical landslide events, and monitor groundwater and landslide m

ment in select areas to aid in reducing landslide hazards in Utah.

For more information:

Geologic Hazards Program: http:/geology.utah.gov/ghp

Landslides: Events and Information: http://geology.utah.gov/utahgeo/hazard/landslide

Geologic Hazard Resources for Homebuyers and Real Estate Agenthttp://geology.utah.gov/utah.geo/hazards/realtors.htm

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obert Ressetar

The coupling of horizontal drilling and hydraulic fracturing ofhale formations has been the most signiicant development

n domestic hydrocarbon production in the past decade. But,s with many aspects of the energy business, controversy hasccompanied it. To date, Utah has experienced little shale-gasroduction compared to other states. However, energy compa-ies have shown interest in several shale formations in Utah,nd Utahs irst commercial horizontally drilled natural gas wellegan production in the Uinta Basin in late 2010. A review of

he controversy that has grown around hydraulic fracturing isherefore timely.

Geologists have long known that shale can contain signiicantmounts of oil and gas. But the small size of the pores in shalend their low degree of connectedness (i.e., low permeability)sually made extracting hydrocarbons from shale uneconomi-

al. By artiicially fracturing the rocks, drilling engineers canreate cracks through which the natural gas will low to thewell bore in much greater amounts than would otherwise be

ossible. The technique of hydraulic fracturing (or fracking)efers to pumping liquids into the well under great pressure,hereby inducing the fractures. Frack luids are typically about5% water and 3% sand, which acts as a proppant, wedging

nto the fractures and keeping them open after the frack luids withdrawn. The remaining 2% of the luid is chemicals thaterve a variety of purposese.g., low enhancers, scale preven-ers, bactericidesand whose precise composition depends onhe characteristics of the speciic frack job.

racking is not a new technique; it dates back to the 1940s. About

5,000 wells in the U.S. are fracked annually, and the domesticotal of fractured wells is nearly one million. Historically, mostractured wells were drilled vertically and the target reservoirs

were sandstone or limestone. The current excitement aboutracking stems from its use in horizontally directed wells torovide extended well contact with the heretofore noncommer-ial shale reservoirs. Like fracking, horizontal drilling has beenmployed for decades, but was relatively unused until techno-ogical advances allowed more accurately aimed and longerorizontal well segments. In horizontal drilling, the well is irstrilled vertically to a certain depth (the kickoff point), thenteered with a directional motor into a horizontal plane withinhe reservoir. The horizontal part of the well may extend thou-ands of feet, thus exposing a larger volume of the reservoir to

he well than would be possible in a vertical well, and allowingmore gas to be produced.

After drilling, the hole is cased with pipe and cement to preventollapse and to prevent luid migration into permeable, non-eservoir rocks. The actual high-pressure pumping of a fracktage lasts only a few hours, and several frack stages may be per-ormed over three to ive days. The luid creates fractures about/10 of an inch wide, commonly widening natural fractures andxploiting weaknesses in the rock. The distance the fracturesxtend from the well depends on the luid injection rate, theolume of luid injected, and the rocks physical properties, buts designed to stay within the target shale interval. Some of the

Schematic diagram of a fractured horizontal gas well completed ithe Mancos Shale of the Uinta Basin. Induced fractures are severathousand feet below the fresh-water aquifer.

Aerial view of typical frack equipment operating in the southern U.S.Photo courtesy of Halliburton.

HYDRAULIC FRACTURING AND SHALE GASENERGY NEWS

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rack luid is retrieved from the well before natural gas productionegins.

The main environmental concern contributing to the controversyver fracking is that natural gas and frack luids could migratelong the fractures and enter groundwater used for domestic orgricultural purposes. This is unlikely for several reasons. In mostracking operations the induced fractures are 2800 to 7500 feetelow the deepest fresh groundwater aquifers. Engineers monitorhe orientation of fractures during the process, and have strongconomic and environmental incentives to prevent fractures

eaching aquifers above the reservoir, because they risk losing theas they hope to produce, and water lowing from aquifers wouldamage the gas reservoir.

everal recent news reports have linked contaminated drinkingwater in Colorado, Ohio, and Pennsylvania to fracking. Investigationshowed, however, that poor well casings, naturally occurring gasn the aquifer, or overpressuring a well during production werehe causes. These are still environmental concerns, but suggesthat the controversy over fracking per se is misdirected. The onenstance where a causal link may exist between fracking and

water contamination is at Pavillion, Wyoming, according to a drafteport by the Environmental Protection Agency in December 2011.

However, in Congressional testimony EPA oficials emphasized thathese indings were unique to Pavillion, where the fractured zones

were as little as 400 feet deeper than some water wells, and did notmply that fracking was inherently unsafe.

arthquakes caused by fracking are another concern. Geologistsave known since the 1960s that pumping luids undergroundear active faults may cause induced seismicity, but inducedarthquakes are typically very small. For example, Youngstown,

Ohio, experienced several earthquakes up to magnitude 4 in 2011,ear a disposal well that pumped used frack luid underground.

Youngstown sits above the north-east Ohio seismic zone, a region ofmoderately frequent naturally occur-ring earthquakes, and geologistsdetermined that the well activated apreviously unknown fault. The welloperator agreed to shut down thewell, and Ohio issued new regulations requiring geologic mtoring of new disposal wells. But since an induced earthquaunlikely to be stronger than those that occur naturally in a g

area, the risk of damage from fracking-induced seismicity is loareas with no geological evidence for strong earthquakes.

Another environmental concern is disposal of the used frack The luid can be temporarily stored in lined pits at the frack siteeventually must be pumped back underground or treated. Dricompanies are increasingly recycling used luid in other frackto conserve additives and reduce use of water and disposal we

Regulations controlling fracking, well completions, and wdisposal are largely a matter of state law. However, Congrecently directed the EPA to investigate the safety of fracregarding drinking water. A irst draft of the report shoulreleased later this year; the inal report is due in 2014. Meanwstate laws on fracking are rapidly changing, mostly by requdisclosure to some degree of the frack luid compositions. Mcompanies voluntarily post the composition of luids onwebsite http://fracfocus.org. By following the links on this sitereader can ind information on more than 400 hydraulically tured wells in Utah.

The great majority of the evidence indicates that hydraulic fraing has been and can continue to be done safely. But as withindustrial process, careful planning and monitoring are necesto prevent accidental environmental harm.

Photo Credit: Clint Ba

Kimm M. Harty

At 6:00 p.m. on January 26, 2012, former and current Utah Geological Survey(UGS) staff members Jim Davis, Valerie Davis, and Kimm Harty joined teachersand students at Lincoln Elementary school in Salt Lake City to dedicate asubstantial rock and mineral collection that was donated to the school byneighborhood resident Glenda Parker. Glendas spouse was Jim Parker, a UGScartographer who passed away in 2008. One of Jims varied interests in life wascollecting rocks and minerals from all over the country. Many of the specimens inthis beautiful collection will be displayed at the school and adjacent communitycenter to be built in the next few years, and some are currently used to teachhands-on science. Even the schools art teacher has requested specimens to usein class.

Prior to the dedication, specimens in Jims collection were identified andorganized by UGS student intern, Patrick McAtee, who educated Lincoln schoolteachers about the types and origins of the rocks and minerals. Ellie Hardman,reading teacher at Lincoln Elementary, organized the dedication ceremony. Wewere happy to see the enthusiasm expressed by the students and teachersreceiving the collection, and how joyful Glenda was to see the donation throughits journey of rising out of dusty basement storage and becoming a focal pointfor learning about earth science at Lincoln Elementary.

THE GREATROCK UNVEILING!

For additional infmation see: http:/energy.utexas.eduphp?option=com_ctent&view=articled=151&Itemid=16

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Marshall Robinson

GEOSIGHTSCOMB RIDGE, SAN JUAN COUNTY, UTAH

Introduction: One may say Comb Ridge was Mother Naturesway of splitting southern San Juan County with an enormous

wall. Another may say it was a giant skateboard ramp fordinosaurs. One thing is certain: Comb Ridge is a spectacularridge of steeply tilted sandstone rock layers, trending north-south for approximately 80 miles from Utahs Abajo Mountainsto Kayenta, Arizona. Similar to a roosters comb, the jaggedappearance of Comb Ridge provides the logic behind its name.

Geologic Information: Comb Ridge is a classic example ofa step-like crease (or fold) in the Earths crust known as a

monocline. Along the axis of the monocline, the rock layers aretilted skyward, whereas they remain relatively lat away fromthe monocline. The exposed rocks at Comb Ridge range in agefrom the Permian-aged Organ Rock Formation (280 millionyears old) to the Jurassic-aged Navajo Sandstone (185 millionyears old).

How to get there: If traveling from thenorth, drive south from Moab on U.S.Highway 191 for approximately 80 milesto the junction with Utah State Route 95.

To view Comb Ridge from the northernroad cut, turn west (right) on SR-95and follow it for 14 miles. Or, continuesouth from Blanding on U.S. 191 throughBluff (here the highway turns into U.S.Highway 163) 30 miles to the southernroad-cut view.

If traveling from the west, drive southand east from Hanksville on Utah StateRoute 95 for approximately 108 miles to

County Road 235. From this view poiyou can continue east on SR-95 to UHighway 191, and travel as describabove to the southern view point.

The best time and place to view ComRidge is in the afternoon on the west sifrom breathtaking road cuts (either UtState Route 95 southwest of Blanding,U.S. Highway 163 west of Bluff). If yhave an extra hour and 4-wheel dritravel along Comb Wash on County Ro235 between SR-95 and U.S. 163 to tain 18 miles of beautiful scenery.

Southeast view o Comb Ridges western fank rom Comb Wash along County Road 235 south o Utah State Route 95. The exrugged light-brown Navajo Sandstone blankets the top o the east-dipping monocline, orming repetitive, sharp peaks and gulch

underlying dark red-brown Kayenta Formation and pale-red Wingate Sandstone orm the rest o the steep sandstone cli. Thvertical severity relaxes at the contact with the slope-orming Chinle Formation, which is mostly covered by a collection o large bo

which have allen rom above. The Moenkopi and Organ Rock Formations make up the rocks along Comb

(continued on page 12)

10 SURVEYNOTES


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Fascinating geology is all around us, even when standing in an

urban park just a stones throw from downtown Salt Lake City.We recently received a call from someone curious about foot-print impressions in the sidewalk at Memory Grove Park, whichis in City Creek Canyon immediately northeast of downtownSalt Lake City. While there is a sidewalk leading to MemoryGrove Park that includes artist representations of local wild-life tracks on inset granite plaques, the caller was referring toancient tracks in the sandstone slab sidewalk within the parkitself.

The caller, Phoebe Bergvall, is a writer for Salt Lake Citys Exam-iner.com, and she found what she described in an online article(www.examiner.com/counterculture-in-salt-lake-city/limping-squirrel-tracks-memory-grove) as actual tracks made by asmall animal millions of years ago. She further speculated that

the tracks could have been made by a squirrel-like creaturewith an injured leg. Phoebes observation that the small markswere tracks proved correct, and her speculation that the trackswere made by a limping squirrel-like creature was pretty close.

To learn more about the tracks, UGS geologists contacted trackresearcher and University of Utah student Tracy Thomson.Tracy visited Memory Grove Park and found four sandstoneslabs with good trackways and a few blocks with other typesof less distinct tracks. Tracy identified what Phoebe found as180-million-year-old (Jurassic) Brasilichnium trackways, whichare thought to be made by a burrowing mammal-like animalnamed Tritylodon. One of these newly discovered Brasili-chnium trackways is significant because it appears to show agalloping or loping locomotion not previously described. Tracy

also found scorpion-like trackways that appear to be verysimilar to Paleohelcura trackways found at Dinosaur NationalMonument.

The sandstone sidewalk has been in Memory Grove Parklonger than anyone working for Salt Lake City can remem-ber, so the stones origin is uncertain. However, the flagstoneslabs are believed to be Nugget Sandstone, probably quarriedin Wasatch County just east of Heber City. The Nugget Sand-stone was once part of a huge sand sea called the Navajoerg, which is thought to have covered Utah and parts of sur-rounding states. This vast expanse of sand was not completelydry. Within the dune fields were shallow lakes that createdhospitable oases for Tritylodons, dinosaurs, reptiles, and otheranimals and plants. Quarried Nugget Sandstone has been used

extensively along the Wasatch Front, so other urban trackwaysand similar wonders may be awaiting discovery.

While fascinating, these trackways are not obvious. I have runover them many times without noticing. How did Phoebe rec-ognize these small divots in the sidewalk as trackways? Shemay be predisposed to acute geologic observation; althoughshe is not a geologist, both her parents were. Furthermore,Phoebes mother, Martha Smith, worked as a geologist forthe UGS from 1977 to 1987 (see the September 2011 issue ofSurvey Notes). Martha Smith was the UGSs first InformationSpecialist, a predecessor to the position I now have.

Immediately northeast of downtown Salt Lake City, the sandstone slabsidewalk in Memory Grove Park contains several ancient and uniquetrackways. This Brasilichnium trackway lies northwest (up canyon) ofthe pond, adjacent to the second tree past the re hydrant (hydrantvisible near the top, center-le of photo). U.S. quarter for scale.

Mark Milligan

Arst concepon of the plants and animals living in the Jurassic Navajoerg (sand sea). Note the two Tritylodons and theirBrasilichniumtrackways. Illustraon by Russell Hawley.

Tritylodon

Tritylod

on

GLAD YOU ASKEDARE THOSE ANIMAL TRACKS IN THE SIDEWALK?

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SURVEY NEWS

TEACHERS CORNER

EMPLOYEE NEWSWelcome to Pam Perri, who accepteda secretary position with the GeologicHazards Program (GHP). Pam previouslyworked as a medical technologist andlegal secretary. The GHP also welcomesAmanda Hintz as a geologist. Amandais currently completing a Ph.D. in Geol-ogy from State University of New Yorkat Buffalo. The Groundwater and Pale-ontology Program bids farewell to TobyHooker who accepted a position withthe Division of Water Quality, a division

of the Department of EnvironmentalQuality.

2011 UGS EMPLOYEE OF THE YEARCongratulations to Jim Davis who was named the 2011 UGSEmployee of the Year. Jim is a geologist in the Geologic Infor-mation and Outreach Program and has worked for the UGS forfive years. He is most often the volunteer for numerous proj-ects that come up, such as leading the Department of NaturalResources finance team field trip, cataloging two major rockand mineral donations, setting up rock and mineral dis-plays for various events, supervising high-school studentinterns, and handling much of the Earth Science Weeklogistics. Jims sense of humor and affability drawpeople to him, and he is always enthusiastic to helpboth UGS staff and the general public. Jim is knowl-

edgeable and professional, and his positive attitudemakes him a deserving recipient of this award.

Block diagram o the Comb Ridge monocline. Deep, underlying rocklayers ruptured along a compressional ault (blind thrust), pushingthe rocks in the west much higher than those in the east. Overlyingrocks, not ruptured by the deep ault, deormed by olding over theruptured layers, creating a monocline.

The steep clis common on one side o many monoclines are mainlythe result o stream erosion. Stream fow in Comb Wash played asignicant role in eroding away hundreds o eet o rock, carving thebeautiul sandstone clis on Comb Ridges west side. Aerial images

rom Google Earth.

Compressional forces during the Laramide mountain-buildingevent (4070 million years ago) uplifted an area of southeastUtah known as the Monument Upwarp. Comb Ridge is the abrupt

eastern lank of the Monument Upwarp. The San Rafael Swell,Uinta Mountains, and Rocky Mountains are examples of othergeologic features that were formed during Laramide time.

(continued from page 10)

Sandy Eldredge

K12 TEACHERS OF EARTH SCIENCES IN UTAHEARTH SCIENCE TEACHER OF THE YEAR AWARDfor Excellence in the Teaching of Natural Resources in the Earth Sciences

CALL FOR NOMINATIONS

The Utah Geological Association (UGA) is accepting nomi-

nations for this award until June 1, 2012. The UGA willaward $1,500 to the winning teacher and will also providethe teachers school with an educational gift.

ELIGIBLE TEACHERS

Utah educators most eligible (who meet the awardrequirements) to apply are those who teach:

4th grade 5th grade 8th grade Integrated Science 9th grade Earth Systems

The purpose of UGAs award is to recognize and support an out-standing K12 earth science/natural resource science teacherUGAs participation in the Earth Science Teacher of the Year com-

petitions held nationwide enables them to provide a candidate forthe regional competition sponsored by the Rocky Mountain Sectionof the American Association of Petroleum Geologists (AAPG). TheSection winner receives $500 and is then entered into the nationaAAPG contest, which awards $5,000 as well as an expense-paid tripto the 2013 AAPG Annual Convention.

Application deadline is June 1, 2012.

Additional information, requirements, and entry forms are availableon the UGA website at:

www.utahgeology.org/wp/?p=474.

12 SURVEYNOTES


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Geologic map of the St. George 7.5quadrangle, Washington County, Utah, byJanice M. Hayden and Grant C. Willis, CD (19p., 2 pl. [contains GIS data]), scale 1:24,000,ISBN 978-1-55791-848-2,

M-251DM ....................... ........................ $24.95

Geologic map of the Henrie Knollsquadrangle, Garfield, Iron, and KaneCounties, Utah, by Robert F. Biek, DavidW. Moore, and L. David Nealey, CD (2 pl.[contains GIS data]), scale 1:24,000, ISBN978-1-55791-850-5,M-252DM ....................... ........................ $24.95

Geologic map of the Plain Cityquadrangle, Weber and Box ElderCounties, Utah, by Kimm M. Harty, MikeLowe, and Stefan M. Kirby, CD (2 pl.[contains GIS data]), scale 1:24,000, ISBN

978-1-55791-859-8,M-253DM ....................... ........................ $24.95

Geologic map of the Hite CrossingLowerDirty Devil River area, Glen CanyonNational Recreation Area, Garfield andSan Juan Counties, Utah, by Grant C. Willis,CD (12 p., 1 pl. [contains GIS data]), scale1:62,500, ISBN 978-1-55791-860-4,M-254DM ....................... ........................ $24.95

Geologic map of Elk Ridge and vicinity,San Juan County, Utah (digitized andmodiied from U.S. Geological SurveyProfessional Paper 474-B, published in

1965), by R.Q. Lewis, Sr., R.H. Campbell, R.E.Thaden, W.J. Krummel, Jr., G.C. Willis, andB. Matyjasik, DVD (12 p., 1 pl. [contains GISdata]), scale 1:62,500, ISBN 978-1-55791-845-1,MP-11-1DM ........................ ................... $24.95

Utah Mining 2010, by Mark Gwynn, KenKrahulec, and Michael Vanden Berg, 21 p.,ISBN 978-1-55791-855-0,C-114 ..........................................................$9.95

Geologic hazards of the Magnaquadrangle, Salt Lake County, Utah, byJessica J. Castleton, Ashley H. Elliott, andGreg N. McDonald, CD (73 p., 10 pl.), ISBN978-1-55791-849-9,

SS-137 ...................... ......................... ..... $24.95

Hydrogeology of Morgan Valley, MorganCounty, Utah, by Janae Wallace, MikeLowe, Jon K. King, Walid Sabbah, and KevinThomas, CD (137 p., 9 pl.), ISBN 978-1-55791-854-3,SS-139 ...................... ......................... ..... $19.95

Geologic and hydrogeologiccharacterization of regionalnongeothermal groundwater resourcesin the Cove Fort area, Millard and BeaverCounties, Utah, by Stefan Kirby, CD (64 p.,2 pl.), ISBN 978-1-55791-854-3,

SS-140 ...................... ......................... ..... $19.95

Gilsonite Veins of the Uinta Basin, byTaylor Boden and Bryce T. Tripp, CD (50 p.,1 pl.), ISBN 978-1-55791-856-7,SS-141 ...................... ......................... ..... $19.95

Reconnaissance of landslides andpreliminary landslide hazardassessment along a portion of BrownsPark Road, Daggett County, Utah, byGregg Beukelman and Ben Erickson, CD (14p.), ISBN 978-1-55791-858-1,RI-271 ...................... ......................... ..... $14.95

Implications of thrust and detachmentfaulting for the structural geology of theThermo Hot Springs KGRA, Utah, by WarrenAnderson and Ronald L. Bruhn, CD (23 p.),OFR-587 ...................... ......................... . $14.95

Evaluation of interferometric syntheticaperture radar (InSAR) techniques formeasuring land subsidence and calculatedsubsidence rates for the Escalante Valley, Utah,1998 to 2006, by Richard R. Forster, CD (25 p.),OFR-589 ...................... ......................... . $14.95

NEW PUBLICATIONS

The Utah Geological Survey received a 2012 National Award in Excellence for Research from the Western States SeismicPolicy Council. The award recognizes the significant contributions to earthquake research and risk reduction made by theUtah Earthquake Working Groups, convened under the auspices of the UGS in cooperation with the Utah Seismic Safety Com-mission and U.S. Geological Survey (USGS). The Utah Earthquake Working Groups have met annually since 2003 to reviewongoing earthquake studies and help prioritize and coordinate Utahs earthquake-hazard research agenda. Three separateworking groups focus on active faulting, earthquake ground shaking, and liquefaction, and have involved over 60 geologists,

seismologists, engineers, and geophysicists from the UGS, USGS, universities, consulting companies, and other Utah stateagencies. William Lund (UGS) accepted the award on behalf of the working group members at the joint 2012 National Earth-quake Conference/Earthquake Engineering Research Institute Annual Meeting in Memphis, Tennessee.

UTAH GEOLOGICAL SURVEY RECEIVESNATIONAL AWARD FOR EARTHQUAKE RESEARCH

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survey notes: may 2012

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