CONTENTS

INTRODUCTION ...... 2 FIELD TRIP...... 4 Stop 1 – G.K. Gilbert Geologic View Park ...... 4 Stop 2 – Penrose Drive Paleoseismic Site ...... 9 Stop 3 – University of Seismograph Stations ...... 13 Stop 4 – Utah State Capitol ...... 15 Stop 5 – Warm Springs Fault ...... 15 Stop 6 – Public Safety Building ...... 16 REFERENCES ...... 17

FIGURES

Figure 1. Five central segments of the Wasatch fault zone ...... 2 Figure 2. Field-trip stops along the Salt Lake City segment of the Wasatch fault zone ...... 3 Figure 3. Prominent fault scarps of the Salt Lake City segment near the mouth of Little Cottonwood Canyon ...... 4 Figure 4. Surface-faulting on the central segments of the Wasatch fault zone ...... 5 Figure 5. Low-sun-angle aerial photograph of Wasatch fault scarps at the mouths of Little Cottonwood and Bells Canyons ...... 6 Figure 6. hydrograph ...... 7 Figure 7. Northern Salt Lake Valley, showing field-trip stops 2 through 6 ...... 8 Figure 8. Correlation of site earthquakes on the Salt Lake City segment ...... 9 Figure 9. Revised surface-faulting chronology for the Salt Lake City segment ...... 10 Figure 10. Schematic cross section across northern Salt Lake Valley ...... 11 Figure 11. Comparison of surface-faulting chronologies for the West Valley fault zone and individual sites on the SLCS ...... 12 Figure 12. Comparison of Salt Lake City segment and West Valley fault zone earthquake chronologies ...... 12 Figure 13. UUSS regional and urban seismic network (December 2012) ...... 13 Figure 14. Earthquakes in the Utah region ...... 14 Figure 15. Construction to seismically retrofit the Utah State Capitol ...... 15 Figure 16. Construction excavation in downtown Salt Lake City ...... 15 Figure 17. Exposure of the Warm Springs fault ...... 16 Figure 18. Construction of the Salt Lake City Public Safety building ...... 16 SLEEPING GIANT: THE EARTHQUAKE THREAT FACING UTAH’S – FIELD TRIP GUIDE

Christopher B. DuRoss and William R. Lund

INTRODUCTION

The Wasatch Front in northern Utah is home to the striking , numerous cities and communities that house about 80% of Utah’s population, and the most continuous, active normal fault in the conterminous ––the Wasatch fault zone (WFZ) (figure 1). Although no large earthquakes have ruptured the WFZ historically, the fault has a well-documented history of numerous surface-faulting earthquakes in the recent geologic past.

On this field trip we will visit prominent fault scarps on the Salt Lake City segment (SLCS) of the WFZ (figure 2), review the Holocene surface-faulting history of the WFZ, and discuss important topics of ongoing research, such as the potential for partial- and multiple-segment ruptures. At the mouth of Little Cottonwood Canyon near the south end of the SLCS, we will visit classic normal-slip fault scarps displacing glacial deposits that were first recognized and described by G.K. Gilbert in 1877, prompting him to issue Utah’s first earthquake-hazard warning in 1883. Near the campus, we will visit the site of a recent paleoseismic investigation on the SLCS, present an updated earthquake chronology for the segment, and consider the seismogenic relation between the WFZ and the antithetic West Valley fault zone (WVFZ) about 10 km to the west (figure 1).

Figure 1. Five central segments of the WFZ. White lines indicate segment boundaries and white circles indicate paleoseismic sites. SLC – Salt Lake City, ULFF – Utah Lake faults and folds, WVFZ – West Valley fault zone. 2

Figure 2. Field-trip stops (yellow triangles) along the SLCS of the WFZ. White circles indicate paleoseismic sites: BL – Baileys Lake, LCC – Little Cottonwood Canyon, SFDC – South Fork Dry Creek. Holocene traces of the SLCS and WVFZ shown in red (ball and bar on downthrown side); Quaternary traces in dashed black (Black and others, 2003). Base map is 2009 color aerial photography (U.S. Department of Agriculture [USDA], 2012) overlain on a 2-m DEM (Utah Automated Geographic Reference Center [AGRC], 2012).

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Figure 3. Prominent fault scarps (white arrows) of the SLCS near the mouth of Little Cottonwood Canyon as photographed by G.K. Gilbert in 1901 (view looking southeast). Uppermost two arrows show fault scarps on the Bells Canyon glacial moraine. Yellow arrow shows approximate location of stop 1. The second half of the field trip will which is currently under construction, to see focus on earthquake monitoring and the seismic-safety design features being research, and risk-reduction measures that incorporated into this state-of-the-art have been applied in Utah. At the University building. of Utah Seismograph Stations, we will discuss the regional seismograph network and historical earthquake catalog, the threat FIELD TRIP of both moderate and large earthquakes, and ongoing seismological research. On a tour of Stop 1 – G.K. Gilbert Geologic View Park the seismic retrofit (completed in 2007) of at the mouth of Little Cottonwood the Utah State Capitol Building we will Canyon discuss expected ground motions at the site, Bill Lund and Chris DuRoss the details of the base-isolation seismic design, and Utah’s approach to earthquake G.K. Gilbert Geologic View Park is near education and outreach. Next we will visit the mouths of Little Cottonwood Canyon the Warm Springs fault―a trace of the WFZ and Bells Canyon––prominent glacier- that enters downtown Salt Lake City and carved valleys in the Wasatch Range (figure was the controlling geologic structure for the 2). Here we will view evidence of Capitol retrofit. Finally, we will tour the Pleistocene glaciers and prehistoric normal new Salt Lake City Public Safety Building, faulting on the SLCS of the WFZ (figure 3),

4 and discuss the rise and fall of late more would occur in the future. These Pleistocene Lake Bonneville. scarps of course formed during surface- faulting earthquakes on the WFZ, which In his classic letter to the Salt Lake Daily forms the structural boundary between the Tribune in September 1883, G.K. Gilbert, actively extending Basin and Range then a senior geologist with the newly Province and the Middle Rocky Mountains formed U.S. Geological Survey, warned in north-central Utah. local residents about the implications of observable fault scarps along the western As one of the best studied intraplate base of the Wasatch Range. Gilbert reasoned faults in the world, the WFZ has played a that large surface-rupturing earthquakes had prominent role in the development and occurred before Mormon settlement and advancement of earthquake geology and

Figure 4. Surface-faulting earthquakes on the central segments of the WFZ. Boxes indicate 2 time ranges and horizontal lines show mean (solid) and modal (dashed) earthquake times based on an unpublished integration of paleoseismic data from Machette and others (1992, 2007), Lund (2005), DuRoss and others (2009, 2011, 2012), and Olig and others (2011) by the Working Group on Utah Earthquake Probabilities (Wong and others, 2011).

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paleoseismology. G.K. Gilbert recognized faulting earthquakes and correspond with that the fault scarps he observed at the base the most developed part of the Wasatch of the prominent Wasatch Range were Front (figure 4). As a result of about three evidence of incremental fault movement decades of research (and about 25 detailed during earthquakes (Gilbert, 1890, 1928). paleoseismic studies), we have substantially Although Gilbert’s pioneering ideas took improved our understanding of the timing, decades to gain acceptance, they eventually recurrence, and displacement of latest led to focused paleoseismic studies of Pleistocene and Holocene surface-faulting prehistoric earthquakes on the WFZ. Early earthquakes on the five central segments and trench studies in the late 1970s and 1980s refined models of rupture extent and fault focused on finding evidence of Holocene segmentation (see reviews for example by earthquakes (e.g., Swan and others, 1980), Lund [2005] and DuRoss [2008]). which formed the basis for models of fault segmentation and earthquake recurrence At least 22 large earthquakes have (Schwartz and Coppersmith, 1984). Ten ruptured the five central fault segments in WFZ segments are now recognized the past about 6000 yr (figure 4), yielding (Machette and others, 1992); however, mean closed earthquake recurrence intervals recent paleoseismic investigations have of about 900–1300 years for individual focused on the five central segments that segments or a composite recurrence interval have evidence of multiple Holocene surface- of about 300 years for the central segments

Figure 5. Low-sun-angle aerial photograph (Cluff and others, 1970; in Bowman and others, 2009) of Wasatch fault scarps at the mouths of Little Cottonwood and Bells Canyons. Yellow arrow indicates approximate location of stop 1 at the G.K. Gilbert Geologic View Park.

6 combined. The most recent large earthquake 14 ka (Oviatt and others, 1992; Godsey and occurred about 300 years ago on the Nephi others, 2005, 2011) (figure 6). Evidence of segment. Together, paleoseismic data for the Lake Bonneville in the area includes WFZ provide important information for shorelines having wave-cut terraces and forecasting earthquake probabilities in the beach berms, lacustrine sand and gravel Wasatch Front region (Working Group on deposited in deltas at the mouths of Big and Utah Earthquake Probabilities; Wong, Little Cottonwood Canyons, and shorelines 2011). Although our understanding of the weakly expressed in the Bells Canyon end WFZ has advanced significantly since the moraine. first trench was excavated in 1978, important questions remain regarding fault The following description of Lake segmentation, dip, and the temporal and Bonneville is modified slightly from spatial variability of earthquake recurrence. DuRoss and Hylland (2012):

Stop 1 is also an excellent location to Lake Bonneville was the most recent view and discuss evidence for glacial and largest of several pluvial lakes to advances and the rise of Lake Bonneville, occupy the eastern during which overlapped in time. Evidence for the Pleistocene. Details of Lake Pleistocene glaciers in the area includes Bonneville’s history are the subjects of ongoing research, but the general glacial outwash, lateral moraines and the record of the rise and fall of the lake is terminal moraine of Bells Canyon, and the well established. As summarized by lateral moraines of Little Cottonwood Currey (1990) and Oviatt and others Canyon. The crest of the Bells Canyon (1992), the Bonneville lake cycle moraine has been vertically displaced 12–25 began around 30 ka. Over time, the m by the SLCS (Swan and others, 1981) lake rose and eventually reached its (figure 5). Lips (2005) indicated a surface highest level at the Bonneville age for the moraine of 15.9 ± 0.7 ka based shoreline (~1550 m [5090 ft] above on two 10Be exposure ages. Comparably, the mean sea level [amsl]) around 18 ka highstand and Provo phases of Lake Bonneville occurred between about 18 and

Figure 6. Lake Bonneville hydrograph from Hylland and others (in review), showing major shoreline levels (after Miller and others, 2012, incorporating Provo shoreline data from Godsey and others, 2005, 2011).

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Figure 7. Northern Salt Lake Valley, showing field-trip stops 2 through 6 and the left step between the East Bench and Warm Springs faults (Personius and Scott, 1992, 2009). Short-dashed red line indicates possible southern extent of the Warm Springs fault (Black and others, 2003). Bonneville (B) and Provo (P) shorelines from Personius and Scott (1992, 2009). RFF – Rudys Flat fault; VSF – Virginia Street fault; UUSS – University of Utah Seismograph Stations. Base map is 2009 high-resolution orthoimagery overlain on a 2-m DEM (AGRC, 2012) with hillshade illumination from the east.

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(all ages in this discussion are in calendar-calibrated kilo-annum [thousand years; ka]). At the Bonneville highstand level, lake water overflowed the Bonneville basin threshold at Zenda in southeastern , spilling into the Snake– Columbia River drainage basin.

Around 17.6 ka, the Zenda threshold failed catastrophically, resulting in a rapid drop in lake level of approximately 110 m during the Bonneville Flood. The lake level stabilized when erosional downcutting was essentially stopped by a bedrock- controlled threshold at Red Rock Pass, about 2.5 km south of Zenda. The lake remained at or near this level until about 14.5 ka (Godsey and others, 2005, 2011), forming the Provo shoreline (~1450 m [4760 ft] amsl).

A climatic change to warmer and drier conditions caused the lake to regress rapidly from the Provo shoreline to near desiccation levels by the end of the Pleistocene (Eardley, 1962; Currey and others, 1988; Currey, 1990). A small rise in lake level to an elevation of 1295 m (4250 ft) amsl marked the Gilbert phase around 12 ka (Oviatt and others, 2005), after which the lake regressed to near modern levels (historical average elev. Figure 8. Correlation of site earthquakes (earthquake-timing 1280 m [4200 ft] amsl). probability density functions [PDFs]) on the SLCS. Site PDFs are derived from OxCal models of the Penrose Drive, Little Stop 2 – Penrose Drive Paleoseismic Site Cottonwood Canyon, and South Fork Dry Creek trench sites Chris DuRoss (DuRoss and others, in review). Preferred correlation model is non-unique, but is supported by proximity of sites, The SLCS and the WVFZ comprise continuity of scarps, and limiting numerical ages. Holocene-active normal faults that together form a 3–12-km-wide intrabasin graben in The SLCS consists of three subsections the northern part of Salt Lake Valley separated by left steps: the 7.5–10-km-long (figures 1 and 2). These faults have evidence Warm Springs fault, 12-km-long East Bench of repeated, large-magnitude (M ~6–7) fault, and 20-km-long Cottonwood fault surface-faulting earthquakes, but because of (Van Horn, 1981; Scott and Shroba, 1985; extensive development along them, Personius and Scott, 1992) (figure 1). The paleoseismic data are limited. East Bench fault consists of large, prominent scarps bounding uplifted and incised

9 alluvial-fan and Lake Bonneville lacustrine for six earthquakes (preferred model) surfaces, and extends as far north as Dry postdating the Provo-phase shoreline of Canyon, north of the University of Utah Lake Bonneville (~14–18 ka) at 4.0 ± 0.5 ka campus (figure 7). To improve the quality (all uncertainties are ±2), 5.9 ± 0.7 ka, 7.5 and resolution of paleoseismic data for the ± 0.8 ka, 9.7 ± 1.1 ka, 10.9 ± 0.2 ka, and East Bench fault, DuRoss and Hylland 12.1 ± 1.6 ka. An additional earthquake (2012, in review) completed a paleoseismic occurred at 16.5 ± 1.9 ka based on an investigation at the Penrose Drive site, at the erosional unconformity that separates north end of the fault (figure 7). Prior to this deformed Lake Bonneville silt and flat-lying study, questions remained regarding the Provo-phase shoreline gravel. timing of Holocene earthquakes on the northern SLCS as previous paleoseismic The timing of earthquakes on the East timing and displacement data were limited Bench fault (Penrose Drive site) corresponds to the Cottonwood fault at the southern end well with that from two previous trench of the SLCS (figure 2). investigations on the Cottonwood fault (Black and others, 1996 and McCalpin, At the Penrose Drive site, DuRoss and 2002) (figure 8). Although questions remain Hylland (2012, in review) excavated two regarding rupture extent, these paleoseismic trenches across an 11-m-high fault scarp data indicate that nine earthquakes (S1–S9) near the northern end of the East Bench ruptured the SLCS following the Bonneville fault. They found colluvial-wedge evidence highstand (figure 9). These earthquakes

Figure 9. Revised surface-faulting earthquake chronology for the SLCS based on the correlation of site earthquakes shown on figure 8.

10 yield mean closed-interval recurrence times Taylorsville fault paleoseismic data. Mean of about 1300 yr (late Holocene), 1600 yr earthquake recurrence intervals for the (Holocene), 1500 yr (post-Provo), and 2000 WVFZ range from 2.0 to 3.6 kyr, depending yr (post-Bonneville). on the time period. These relatively long mean recurrence intervals for the WVFZ On the floor of northern Salt Lake likely stem from an incomplete earthquake Valley, the WVFZ consists of intrabasin record on account of limited paleoseismic normal faults that span an area 16 km long data and the complex pattern of faulting. by 1–6 km wide (figure 2). The two subparallel, northwest-trending main traces Figures 11 and 12 show WVFZ of the fault zone and their associated earthquake timing compared to individual subsidiary traces are known as the Granger SLCS site chronologies and the revised fault (western traces) and Taylorsville fault chronology for the SLCS as a whole, (eastern traces). DuRoss and Hylland (2012, respectively. Based on comparison of SLCS in review) also conducted a paleoseismic and WVFZ earthquake timing and investigation of the WVFZ (Baileys Lake displacement data, DuRoss and Hylland site)––which is antithetic to the SLCS (2012, in review) concluded that large (figure 10)––to address questions regarding earthquakes on the WVFZ that are coseismic the seismogenic relation between the two with or triggered by fault movement on the fault zones (e.g., can the WVFZ generate SLCS have a higher likelihood than WVFZ independent earthquakes?). earthquakes that occur independently of movement on the SLCS. When considered Six earthquakes (W1–W6) have been together with mechanical and geometric documented on the WVFZ since ~18 ka models of the fault system, the paleoseismic (Hylland and others, in review) (figure 11). data support a high likelihood for The WVFZ earthquake chronology is synchronous rupture of the WVFZ with the developed from both Granger fault and SLCS.

Figure 10. Schematic cross section across northern Salt Lake Valley (figure 2), showing possible subsurface geometries of the SLCS and WVFZ. Dashed black line indicates a likely inactive strand of the SLCS.

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Figure 11. Comparison of surface-faulting chronologies for the WVFZ and individual sites on the SLCS (from Hylland and others, in review). Note that the times of earthquakes W1 and W2 are based on 14C ages of samples from consultant trenches, and W1 timing is constrained by a single limiting age. Schematic Lake Bonneville chronology shown at the same temporal scale for comparison with late Pleistocene earthquake times. Sources of earthquake timing information: WVFZ—Hylland and others (in review); Penrose Drive site—DuRoss and others (in review); Little Cottonwood Canyon site—McCalpin (2002), modified by OxCal modeling (DuRoss and others, in review); South Fork Dry Creek/Dry Gulch site—Black and others (1996), modified by OxCal modeling (DuRoss and others, in review).

Figure 12. Comparison of SLCS and WVFZ earthquake chronologies, showing very similar timing PDFs for S1-W1, S2- W2, and S4-W3. S8-W4 and S9-W6 overlap, but have broadly constrained PDFs. The PDF for W5 does not indicate a clear temporal association with a SLCS earthquake, possibly as a result of two WVFZ earthquakes triggered by a single SLCS earthquake (S8?). Alternatively, evidence for a SLCS earthquake around the time of W5 may have been removed by erosion or otherwise not documented in the previous SLCS trench exposures.

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Stop 3 – University of Utah Seismograph topics such as mining-induced seismicity, Stations infrasound, and slip models from back- Kris Pankow, University of Utah projected phases. Seismograph Stations

The University of Utah Seismograph Stations (UUSS) is a research, educational, and public- service entity within the university's Department of Geology and Geophysics. UUSS operates a regional and urban seismic network of more than 200 stations serving the populations of Utah, eastern Idaho, and western Wyoming (figure 13). The first and foremost mission of UUSS is academic research. At the same time - because of its special facilities and expertise - UUSS carries a major burden to meet the needs and expectations of a host of users in Utah and the Intermountain region for earthquake information (figure 14). We provide information for earthquakes in Utah and Yellowstone, including locations, magnitudes, and where possible, shakemaps and moment tensors. Our research interests include

Figure 13. UUSS regional and urban seismic network (December 2012).

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Figure 14. Earthquakes in the Utah region, showing instrumental seismicity between 1962 and 2012 (circles) and large historical earthquakes (starbursts) that have occurred in the area following pioneer settlement at about 1850.

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Stop 4 – Utah State Capitol Salt Lake City. The fault may continue an Jerod Johnson, Reaveley Engineers additional 3 km toward Salt Lake City (short-dashed red line on figure 7) based on evidence of surface faulting interpreted from construction exposures (Simon-Bymaster, Inc., 1999; figure 16) and the results of a cone-penetrometer study along 400 South (figure 7), which found about 10 m of vertical offset in Lake Bonneville sediments (Leeflang, 2008). Holocene surficial deposits mapped by Personius and Scott (1992) showed evidence of relatively recent (mid-Holocene) surface faulting on the Warm Springs fault; however, these unconsolidated sediments have since been Figure 15. Construction to seismically retrofit the removed by aggregate mining. Thus, the Utah State Capitol. Photograph taken September 2006. timing of Holocene surface-faulting earthquakes on the Warm Springs fault is The Utah State Capitol building (figure unknown. A positive aspect of surface 15) was constructed between 1912 and 1914 mining is the exposure of fault planes in using blocks of Oligocene quartz monzonite Mississippian limestone (figure 17). from Little Cottonwood Canyon (figure 2). Because the stones were stacked (not At this stop we will view polished anchored), the building was susceptible to surfaces of fault-zone breccia containing damage and possible collapse from slickenlines as well as a breached fault core horizontal loads that could be generated in a zone in Mississippian limestone with a magnitude 7.0 earthquake (e.g., on the warm spring flowing from it. A cross section SLCS). Thus, a seismic retrofit of the of the fault-damaged bedrock includes Capitol began in 2004, and consisted of the porous breccia, densely fractured porous addition of base isolators to decouple the protobreccia, and less densely fractured building from horizontal ground motions, protobreccia. vertical shear walls to limit inter-story drift, and other seismic mitigation (Solomon and others, 2005).

Stop 5 – Warm Springs Fault David Dinter, University of Utah

The Warm Springs fault on the northern SLCS extends at least 7.5 km from North Salt Lake to near downtown Figure 16. Construction excavation (ca. 1999) in downtown Salt Lake City showing evidence for surface faulting and liquefaction. Horizontal lines are 1 ft (0.3 m) apart. Photograph by Gary Christenson.

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Figure 17. Exposure of the Warm Springs fault (north of Salt Lake City) in Mississippian limestone. Photograph taken April 2012.

Stop 6 – Salt Lake City Public Safety Building

Our last stop will be at the nearly complete Salt Lake City Public Safety Building (figure 18), which will include a new Emergency Operations Center. On our tour, we will observe and discuss the seismic-safety design features being incorporated into this state-of-the-art building. This building is also being designed to a Net Zero Energy emissions standard. According to Salt Lake City:

…the new building will produce at least as much emissions-free renewable energy as it would otherwise consume if obtained from emissions-producing energy sources. Net Zero Energy will be achieved by dramatically reducing building energy use and utilizing renewable energy. Energy use reduction is accomplished with high efficiency building and systems design, building operations, and occupant energy management strategies. Figure 18. Construction of the Salt Lake City Public Safety building; Renewable energy is produced by photograph taken March 2013. photovoltaic and solar thermal arrays. 16

REFERENCES DuRoss, C.B., 2008, Holocene vertical Black, B.D., Hecker, S., Hylland, M.D., displacement on the central segments of the Christenson, G.E., and McDonald, G.N., Wasatch fault zone, Utah: Bulletin of the 2003, Quaternary fault and fold database Seismological Society of America, v. 98, p. and map of Utah: Utah Geological Survey 2918-2933. Map 193DM, scale 1:50,000, CD. DuRoss, C.B., and Hylland, M.D., 2012, Black, B.D., Lund, W.R., Schwartz, D.P., Gill, Paleoseismic investigation to compare H.E., and Mayes, B.H., 1996, Paleoseismic surface faulting chronologies of the West investigation on the Salt Lake City segment Valley fault zone and Salt Lake City of the Wasatch fault zone at the South Fork segment of the Wasatch fault zone, Salt Dry Creek and Dry Gulch sites, Salt Lake Lake County, Utah: Final Technical Report County, Utah—Paleoseismology of Utah, to the U.S. Geological Survey, National Volume 7: Utah Geological Survey Special Earthquake Hazards Reduction Program, Study 92, 22 p., 1 plate, available online at award no. G10AP00068, 61 p., 2 plates, 12 http://ugspub.nr.utah.gov/publications/sp appendices, available online at ecial_studies/SS-92.pdf. http://geology.utah.gov/ghp/consultants/p ubs/saltlake.htm. Bowman, S.D., Beisner, K., and Unger, C., 2009, Compilation of 1970s Woodward- DuRoss, C.B., and Hylland, M.D., in review, Lundgren & Associates Wasatch fault Evaluating surface faulting chronologies of investigation reports and oblique aerial graben-bounding faults in Salt Lake Valley, photography, Wasatch Front and Cache Utah––new paleoseismic data from the Salt Valley, Utah and Idaho: Utah Geological Lake City segment of the Wasatch fault Survey Open-File Report 548, 3 p., 6 plates, zone and the West Valley fault zone: Utah 9 DVDs. Geological Survey Special Study.

Cluff, L.S., Brogan, G.E., and Glass, C.E., 1970, DuRoss, C.B., Hylland, M.D., McDonald, G.N., Wasatch fault, northern portion—earthquake Crone, A.J., Personius, S.F., Gold, R., and fault investigation and evaluation, a guide to Mahan, S.A., in review, Holocene and latest land-use planning: Oakland, California, Pleistocene paleoseismology of the Salt Woodward-Clyde and Associates, Lake City segment of the Wasatch fault unpublished consultant report for the Utah zone at the Penrose Drive trench site, in Geological and Mineralogical Survey, DuRoss, C.B., and Hylland, M.D., variously paginated. Evaluating surface faulting chronologies of graben-bounding faults in Salt Lake Valley, Currey, D.R., 1990, Quaternary paleolakes in the Utah––new paleoseismic data from the Salt evolution of semidesert basins, with special Lake City segment of the Wasatch fault emphasis on Lake Bonneville and the Great zone and the West Valley fault zone: Utah Basin, U.S.A.: Palaeogeography, Geological Survey Special Study. Palaeoclimatology, Palaeoecology, v. 76, p. 189–214. DuRoss, C.B., Personius, S.F., Crone, A.J., McDonald, G.N., and Briggs, R., 2012, Late Currey, D.R., Berry, M.S., Green, S.A., and Holocene earthquake history of the Brigham Murchison, S.B., 1988, Very late City segment of the Wasatch fault zone at Pleistocene red beds in the Bonneville basin, the Hansen Canyon, Kotter Canyon, and Utah and Nevada [abs.]: Geological Society Pearsons Canyon trench sites, Box Elder of America Abstracts with Programs, v. 20, County, Utah—Paleoseismology of Utah, no. 6, p. 411. Volume 22: Utah Geological Survey Special Study 142, 28 p., 3 plates, 5 appendices, 17

CD., available online at Palaeoecology, v. 310, no. 3–4, p. 442–450 http://geology.utah.gov/ghp/consultants/ (doi: 10.1016/j.palaeo.2011.08.005). paleoseismic_series.htm. Hylland, M.D., DuRoss, C.B., McDonald, G.N., DuRoss, C.B., Personius, S.F., Crone, A.J., Olig, S.S., Oviatt, C.G., Mahan, S.A., McDonald, G.N., and Lidke, D.J., 2009, Crone, A.J., and Personius, S.F., in review, Paleoseismic investigation of the northern Late Quaternary paleoseismology of the Weber segment of the Wasatch fault zone at West Valley fault zone—insights from the the Rice Creek trench site, North Ogden, Baileys Lake trench site, in DuRoss, C.B., Utah—Paleoseismology of Utah, Volume and Hylland, M.D., Evaluating surface 18: Utah Geological Survey Special Study faulting chronologies of graben-bounding 130, 37 p., 2 plates, CD, available online at faults in Salt Lake Valley, Utah—new http://geology.utah.gov/online/ss/ss- paleoseismic data from the Salt Lake City 130.pdf. segment of the Wasatch fault zone and the West Valley fault zone: Utah Geological DuRoss, C.B., Personius, S.F., Crone, A.J., Olig, Survey Special Study. S.S., and Lund, W.R., 2011, Integration of paleoseismic data from multiple sites to Leeflang, B.A., 2008, Ground displacement develop an objective earthquake investigations in downtown Salt Lake City, chronology––application to the Weber Utah, using the cone penetrometer: Salt segment of the Wasatch fault zone: Bulletin Lake City, University of Utah, M.S. thesis, of the Seismological Society of America, v. 160 p. 101, no. 6, p. 2765–2781. Lips, E.W., 2005, Revised chronology of late Eardley, A.J., 1962, Glauber’s salt bed west of Pleistocene glaciers, Wasatch Mountains, Promontory Point, Great Salt Lake: Utah Utah [abs.]: Geological Society of America Geological and Mineralogical Survey Abstracts with Programs, v. 37, no. 7, p. 41. Special Study 1, 12 p. Lund, W.R., 2005, Consensus preferred Gilbert, G.K., 1890, Lake Bonneville: U.S. recurrence-interval and vertical slip-rate Geological Survey Monograph 1, 438 p. estimates—review of Utah paleoseismic- trenching data by the Utah Quaternary Fault Gilbert, G.K., 1928, Studies of basin-range Parameters Working Group: Utah structure: U.S. Geological Survey Geological Survey Bulletin 134, 109 p., Professional Paper 153, 92 p. CD., available online at http://ugspub.nr.utah.gov/publications/b Godsey, H.S., Currey, D.R., and Chan, M.A., ulletins/B-134.pdf. 2005, New evidence for an extended occupation of the Provo shoreline and Machette, M.N., Crone, A.J., Personius, S.F., implications for regional climate change, Mahan, S.A., Dart, R.L., Lidke, D.J., and Pleistocene Lake Bonneville, Utah, USA: Olig, S.S., 2007, Paleoseismology of the Quaternary Research, v. 63, no. 2, p. 212– Nephi segment of the Wasatch fault zone, 223. Juab County, Utah—preliminary results from two large exploratory trenches at Godsey, H.S., Oviatt, C.G., Miller, D.M., and Willow Creek: U.S. Geological Survey Chan, M.A., 2011, Stratigraphy and Scientific Investigations Map SI-2966, 2 chronology of offshore to nearshore deposits plates, available online at associated with the Provo shoreline, http://pubs.usgs.gov/sim/2007/2966/. Pleistocene Lake Bonneville, Utah: Palaeogeography, Palaeoclimatology,

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Machette, M.N., Personius, S.F., and Nelson, Oviatt, C.G., Miller, D.M., McGeehin, J.P., A.R., 1992, Paleoseismology of the Wasatch Zachary, C., and Mahan, S., 2005, The fault zone—a summary of recent Younger Dryas phase of Great Salt Lake, investigations, interpretations, and Utah, USA: Palaeogeography, conclusions, in Gori, P.L., and Hays, W.W., Palaeoclimatology, Palaeoecology, v. 219, editors, Assessment of regional earthquake p. 263–284. hazards and risk along the Wasatch Front, Utah: U.S. Geological Survey Professional Personius, S.F., and Scott, W.E., 1992, Surficial Paper 1500-A, p. A1–A71., available online geologic map of the Salt Lake City segment at and parts of adjacent segments of the http://pubs.er.usgs.gov/publication/pp15 Wasatch fault zone, Davis, Salt Lake, and 00AJ. Utah Counties, Utah: U.S. Geological Survey Miscellaneous Investigations Series McCalpin, J.P., 2002, Post-Bonneville Map I-2106, scale 1:50,000. paleoearthquake chronology of the Salt Lake City segment, Wasatch fault zone, from the Personius, S.F., and Scott, W.E., 2009 (digital 1999 “megatrench” site—Paleoseismology release), Surficial geologic map of the Salt of Utah, Volume 10: Utah Geological Lake City segment and parts of adjacent Survey Miscellaneous Publication 02-7, 37 segments of the Wasatch fault zone, Davis, p., Salt Lake, and Utah Counties, Utah http://ugspub.nr.utah.gov/publications/m (digitized from U.S. Geological Survey isc_pubs/MP-02-7WFZ-SLC.pdf. Miscellaneous Investigations Series Map I- 2106 [1992]): Utah Geological Survey Map Miller, D.M., Oviatt, C.G., and McGeehin, J.P., 243DM, GIS data, scale 1:50,000. 2012, Stratigraphy and chronology of Provo shoreline deposits and lake-level Schwartz, D.P., and Coppersmith, K.J., 1984, implications, late Pleistocene Lake Fault behavior and characteristic Bonneville, eastern Great Basin, USA: earthquakes—examples from the Wasatch Boreas, 20 p. (doi:10.1111/j.1502- and zones: Journal of 3885.2012.00297.x). Geophysical Research, v. 89, p. 5681–5698.

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