sltrib.com
New research suggests a seismic connection ties the Salt Lake portion of the Wasatch Fault with the parallel West Valley fault zone about six miles to the west. The two frame the Salt Lake Valley and a potential, simultaneous rupture could make Salt Lake’s “Big One” a little bigger.
Chris DuRoss and Michael Hylland of the Utah Geological Survey reported these findings at the Seismological Society of America meeting Wednesday in Salt Lake City.
Video highlighting a recent trench investigation of the Wasatch fault
The Wasatch fault is Utah’s longest and most active fault, extending along the Wasatch Front from southern Idaho to central Utah. Although no large earthquakes have ruptured the fault historically, abundant geologic evidence indicates that the fault is capable of generating earthquakes as large as magnitude 6.5–7.5.
This video takes you along the trace of the Wasatch fault, showing its proximity to cities and towns in the Wasatch Front region, and also highlighting the history of past large earthquakes on the central, most active segments of the fault. The video also includes footage from a recent trench investigation at the North Creek site on the Nephi segment of the fault, and describes how geologists interpret evidence of large, prehistoric earthquakes.
kcsg.com
More than 74,000 aerial photographs covering Utah are now available on the Utah Geological Survey (UGS) website. The UGS Aerial Imagery Collection web application allows easy access, viewing, and downloading of aerial photographs. Various federal agencies, the UGS, and other organizations originally acquired these photographs for a variety of agricultural, geologic, and land-use purposes. Additional aerial photographs are being added.
Congratulations to Jay Hill who was named the 2012 UGS Employee of the Year. Jay is a GIS analyst in the Editorial section and has worked for the UGS for four years. His excellent work, positive attitude, and sense of humor make Jay a deserving recipient of the UGS Employee of the Year Award.
LATE HOLOCENE EARTHQUAKE HISTORY OF THE BRIGHAM CITY SEGMENT OF THE WASATCH FAULT ZONE AT THE HANSEN CANYON, KOTTER CANYON, AND PEARSONS CANYON TRENCH SITES, BOX ELDER COUNTY, UTAH
By Christopher B. DuRoss, Stephen F. Personius, Anthony J. Crone, Greg N. McDonald, and Richard W. Briggs
This report (28 p. + 5 appendices, and 3 plates) presents new information on the timing and displacement of late Holocene surface-faulting earthquakes on the Brigham City segment of the Wasatch fault zone, collected as part of a joint Utah Geological Survey and U.S. Geological Survey seismic-hazard evaluation. Paleoseismic data from two trench sites on the northern Brigham City segment (Hansen Canyon and Kotter Canyon sites) confirm the timing of the youngest surface-faulting earthquake, and results from a trench site on the previously unstudied southern part of the segment (Pearsons Canyon site) have important fault-segmentation implications. These results help clarify the timing, recurrence, and extent of large-magnitude earthquakes on the Brigham City segment, which will help improve seismic-hazard evaluations of the region. This study was partially funded by the National Earthquake Hazards Reduction Program.
Special Study 142 $19.95
GREAT SALT LAKE BRINE CHEMISTRY DATABASE, 1966–2011
by Andrew Rupke and Ammon McDonald
This open-file release includes a brief 7-page report and the Great Salt Lake brine chemistry database in digital format. The report briefly describes the Great Salt Lake brine sampling program and database that the Utah Geological Survey has conducted and maintained since 1966. The Great Salt Lake brine chemistry database includes information on chemistry, salinity, and density of Great Salt Lake brine samples that have been collected from over 50 locations on Great Salt Lake. For this release the database has been reorganized into one Excel spreadsheet file for ease of use.
Open-File Report 596 $14.95
MODERATELY SALINE GROUNDWATER IN THE UINTA BASIN, UTAH
By Paul B. Anderson, Michael D. Vanden Berg, Stephanie Carney, Craig Morgan, and Sonja Heuscher
The base of the moderately saline water (BMSW) (10,000 mg/L TDS transition) in the Uinta Basin was first mapped in 1987 and re-mapped in this study using similar methods. Water samples from primarily oil and gas activities through the basin’s history were compiled into a database (2788 records) and used as an aid in mapping. In addition, geophysical logs from 260 wells distributed throughout the basin were interpreted and used in mapping the BMSW. Regional groundwater flow paths, saline minerals, structural shape of the basin, and faults and fractures strongly influence the distribution of TDS levels. Both older and new data points were used to create an elevation contour map of the position of the shallowest occurrence of the BMSW below the surface. Depth-correlated water analysis data were mapped and compared to the log-derived BMSW. Mapped water analysis data indicate the northern portion of the basin has numerous occurrences of water fresher than 10,000 mg/L below the BMSW, indicating a complex stratification of salinity coincident with the area of primary recharge, whereas shallow saline waters dominate the central portion of the basin. 30-page report + 9 plates
Special Study 144 $24.95
Interim Geologic Map of the Rush Valley 30′ x 60′ Quadrangle, Tooele, Utah, and Salt Lake Counties, Utah
By Donald L. Clark, Stefan M. Kirby, and Charles G. Oviatt
This CD contains two plates—the geologic map at 1:62,500 scale and the explanation sheet—plus a 62-page booklet, all in PDF format.
Open-File Report 593 $19.95
A 3-minute, time-lapse video, taken over 10 days, showing the excavation and study of the North Creek trench on the Nephi segment of the Wasatch fault zone.
by Bruce Vandre
Dixie State College Community Education Call #: 25586
Date: Feb 25, 2012, 9:30am-‐4:30pm
Place: DSC, Smith Computer Center, Rm 118
Call 652-‐7675 for info.
Class Fee: $38 per person
Lab Fee: $10 payable to Community Education
Digital map and location referencing technology is rapidly changing. This class will survey available resources and demonstrate select tools. References will include Internet sites and tutorials. The class will be held in a computer laboratory enabling software use and experimentation. The Utah Department of Professional Licensing is providing a grant for the continuing education of Professional Geologists that has reduced the registration fee. Class attendance is limited to the number of computers available, 25.
The class content will include:
Bruce Vandre has worked in civil engineering for over 40 years. He has been employed by Engineering Consultants in San Francisco, Portland, and Salt Lake City, the USDA Forest Service, and Utah Department of Transportation. He has had a professional geology license in Oregon and engineering licenses in Oregon, Washington, Idaho, Wyoming, Utah, and Colorado. During retirement he has updated his GPS and GIS skills for personal research projects. His web site is Vanmontage.org.
Great Salt Lake has islands from small to large, from one corner of the lake to the other. But how many islands are there? The question is not as straightforward as one might think. Although there are 17 officially named islands, answers to the question typically range from zero to 15.
It All Depends. . .
Great Salt Lake is in a closed basin, an area without any drainage outlet. The elevation of the lake’s surface changes continually, reflecting changes in weather and climate; heavy precipitation and low evaporation rates cause the lake level to rise, whereas drought and heat will result in a declining lake level. The lake level can change 2-plus feet a year, and because the basin floor slopes very gently, the shoreline advance or retreat can be a mile or more in certain areas.
Great Salt Lake’s ups and downs have exceeded a 20-foot range in historical times. At high lake levels some islands submerge and new ones are created by the water enclosing higher topography. At low lake levels new islands emerge and some adjacent islands merge with each other or with the mainland.
The Utah Geological Survey (UGS) is a division of the Utah Department of Natural Resources. Several specialized programs comprise the UGS: Data Management, Energy & Minerals, Geologic Hazards, Geologic Information & Outreach, Geologic Mapping, Groundwater & Wetlands, and Paleontology.
1594 West North Temple, Suite 3110
Salt Lake City, Utah 84116
801-537-3300 (phone)
801-537-3400 (fax)
Mailing Address:
PO BOX 146100
Salt Lake City, Utah 84114
Monday through Friday,
8 a.m. to 5 p.m.
