A uniform moment magnitude earthquake catalog and background seismicity rates for the Wasatch Front and surrounding Utah region: Appendix E in Working Group on Utah Earthquake Probabilities (WGUEP)

Arabasz, W.J., Pechmann, J.C., and Burlacu, R., 2016, A uniform moment magnitude earthquake catalog and background seismicity rates for the Wasatch Front and surrounding Utah region: Appendix E in Working Group on Utah Earthquake Probabilities (WGUEP), 2016, Earthquake probabilities for the Wasatch Front region in Utah, Idaho, and Wyoming: Utah Geological Survey Miscellaneous Publication 16-3, variously paginated.

This appendix to the report by the Working Group on Utah Earthquake Probabilities (2016) describes full details of the construction and analysis of a refined earthquake catalog and the calculation of seismicity rates for the Wasatch Front and surrounding Utah region. The earthquake catalog covers the period from 1850 through September 2012. The catalog region extends from lat. 36.75° to 42.50° N and from 108.75° to 114.25° W. A uniform moment magnitude, M (and quantified magnitude uncertainty), is determined for each earthquake in the catalog.

Electronic Supplements (.xlsx)

E-1.  Best-Estimate Moment Magnitude (BEM) Earthquake Catalog

E-2.  Moment Magnitude Data

E-3.  Merged Subcatalog A, Jan. 1850-June 1962

E-4.  Merged Subcatalog B, July 1962-Dec. 1986

E-5.  Merged Subcatalog C, Jan. 1987-Sept. 2012

E-6.  Worksheets for Mobs, M~, Mpred (I0)

E-7.  Worksheets for Xnon, Xmix (Subcatalogs A, B)

E-8.  Worksheets for Xvar, Xi (Subcatalog B)

E-9.  Worksheets for Xvar, Xi (Subcatalog C)

E-10.  N* Counts for the WGUEP and Utah Regions

Earthquake Probabilities for the Wasatch Front region in Utah, Idaho, and Wyoming

Wong, I., W. Lund, C. DuRoss, P. Thomas, W. Arabasz, A. Crone, M. Hylland, N. Luco, S. Olig, J. Pechmann, S. Personius, M. Petersen, D. Schwartz, R. Smith, and S. Bowman (2016). Earthquake Probabilities for the Wasatch Front region in Utah, Idaho, and Wyoming, Utah Geological Survey Miscellaneous Publication 16-3,  418 pp.

UUSS 2015 Annual Report

UUSS Annual Report 2015

2015 Annual Report

2015 has been another vibrant and productive year for the University of Utah Seismograph Stations (UUSS). Our longstanding partnership with the United States Geological Survey (USGS) was extended with a new, 5-yr cooperative agreement from the USGS Earthquake Hazards Program. This award ensures that earthquake monitoring in Utah will continue to operate with state-of-the-art equipment and software at least through 2020. Congratulations to the UUSS staff for all their hard work on the USGS proposal, it was truly a team effort.

The legacy of UUSS in earthquake monitoring and research was recognized in 2015 as two former UUSS Directors received prestigious awards for career accomplishments. Research Professor Emeritus Dr. Walter J. Arabasz received the 2015 Alfred E. Alquist Special Recognition Medal from the Earthquake Engineering Research Institute, while Professor Emeritus Dr. Robert B. Smith received the 2015 Paul G. Silver Award from the American Geophysical Union. Congratulations to Walter and Bob for the leadership and service they have provided to the seismological community over the last several decades.

UUSS developed a new monitoring capability in 2015 with the acquisition of nearly 50 new wireless seismographs. The instruments were purchased in collaboration with Dr. Fan-Chi Lin and other University of Utah geoscientists, and will allow for the imaging of shallow Earth structure at a very small scale as well as the detection of small aftershocks that follow regional earthquakes. Please look inside to read about one of the first experiments carried out with the new instruments.

We expect great new things in 2016 as well. Keep an eye out for an updated UUSS web page and expanded social media presence. We also look forward to a celebration of the 50th anniversary of UUSS, in April 2016.

Tracking North America: Long‐term Observation to Build on the Legacy of USArray

West, M., S. Bilek, P. Boden, G. Kent, K. Koper, W.‐Y. Kim, N. Ruppert, V. Tsai, and J. Vidale (2015). Tracking North America: Long‐term Observation to Build on the Legacy of USArray, whitepaper for workshop on Future Seismic and Geodetic Facility Needs in the Geosciences, Leesburg, Virginia, May 4‐6, pp. 1‐2.

Paleoseismology of the northern segments of the Great Salt Lake fault, Utah

Dinter, D. A., and J. C. Pechmann (2015). Paleoseismology of the northern segments of the Great Salt Lake fault, Utah, in Proc. of the Basin and Range Province Seismic Hazards Summit III, Salt Lake City, Utah, January 12‐17, W. R. Lund (Editor), Utah Geological Survey Misc. Publ. 15‐5, CD (electronic poster).

Scenario for a Magnitude 7.0 Earthquake on the Wasatch Fault–Salt Lake City Segment: Hazards and Loss Estimates

Pankow, K., W. J. Arabasz, R. Carey, G. Christenson, J. Groeneveld, B. Maxfield, P. W. McDonough, B. Welliver,
Segment: Hazards and Loss Estimates, Earthquake Engineering Research Institute, Utah Chapter, 53 p.

Paleoseismology of the Promontory Segment, East Great Salt Lake Fault

Dinter, D. A., and J. C. Pechmann (2014). Paleoseismology of the Promontory Segment, East Great Salt Lake Fault, U.S. Geol. Surv. Final Technical Rept., Award No. 02HQGR0105, 23 pp, http://earthquake.usgs.gov/research/external/reports/02HQGR0105.pdf
With funding from this project, we collected 367 km of high resolution seismic reflection data in the Great Salt Lake in 2003 and 2006: 205 km in the north arm and 162 km in the south arm, where the north and south arms are defined as the parts of the lake north and south of the railroad causeway, respectively.  Because the quality of the north arm data that we obtained was insufficient to meet the goals of the project, we collected an additional 380 km of data with new, state-of-the-art instrumentation in 2009 and 2010: 160 km in the north arm and 220 km in the south arm. The 2009 fieldwork was part of a collaborative industry-funded study. The 2010 field work was carried out using boat and equipment time that became available after the successful completion of a seismic reflection study in Utah Lake for another USGS/NEHRP-funded study.
We used the seismic reflection data to map the Great Salt Lake fault (GSLF) and associated subsidiary faults in the north arm of the Great Salt Lake and to revise an analogous map for the south arm of the lake that we constructed for a previous USGS/NEHRP-funded project. We also mapped the trace of the Carrington fault, another major normal fault in the Great Salt Lake, using our seismic reflection data and high-resolution bathymetry data for the lake.  Based on the geometry of our mapped surface trace for the GSLF, variations in the amount of lakebed offset along this fault, and other evidence for recency of faulting, we hypothesize that the GSLF consists of the following four segments from north to south (with end-to-end length measurements): the Rozel segment (≥ 18 km), the Promontory segment (≥27 km), the Fremont Island segment (24 km), and the Antelope Island segment (35 km).
Seismic reflection profiles across the GSLF in the north arm show clear evidence for individual paleoearthquakes in the form of stratigraphically limited subsidiary faults and monoclines and coseismic bedding rotations adjacent to the fault. Based on these types of features, we have identified seismic event horizons for two or three paleoearthquakes on the Rozel segment and two or three paleoearthquakes on the Promontory segment , all within ~8 m of the lake bottom.  A possible fourth Promontory segment earthquake is suggested by the higher fault scarps along this segment. The earthquake event horizons that we have identified in this study can be cored and dated to establish a paleoearthquake history for the Rozel and Promontory segments of the GSLF. In the meantime, based on comparisons with the depths of dated event horizons on the Antelope Island and Fremont Island segments, it seems reasonable to assume that the average recurrence interval of 4200 ±1400 years that we have determined for these two segments is also applicable to the Rozel and Promontory segments

UUSS 2014 Annual report

uuss_ar2014 cover2014 Annual Report

Dear Friends,
It is a pleasure to present you with the 2014 Annual Report of the University of Utah seismograph Stations (UUSS). Reflecting on recent UUSS accomplishments, I was struck by the importance of partnerships in pursuing our dual mission of academic research in earthquake science, and communication to the residents of Utah of the latest information on earthquake risk.
As always, a key UUSS partner in 2014 was our home academic unit, the Department of Geology and Geophysics. A nice example of the support shown by our department is the recent hire of a new tenure-track faculty member in seismology, Dr. Fan-Chi Lin. Although Dr. Lin’s expertise is in seismic imaging, he has already expressed interest in collaborating with UUSS faculty on projects related to earthquake science in Utah and Yellowstone.
A second important UUSS partner is the Utah Division of Emergency Management (DEM). This agency administers Utah’s earthquake program and has the responsibility for mitigating and responding to earthquake hazards in the state. The DEM earthquake program funds the UUSS traveling earthquake exhibit, which visited 25 elementary and middle schools throughout Utah in 2014. The DEM also provides financial support for the Utah Seismic Safety Commission, the state’s official earthquake advisory board.
A third partner that is essential to the success of UUSS is the United States Geological Survey (USGS).  The USGS routinely and consistently supports UUSS by providing the latest seismic equipment—and the funding to operate and maintain this equipment. In 2014, USGS funding enabled over 115 seismic stations to be operated in the State of Utah. As with all of our
seismometers, these instruments operate 24 hours a day, 7 days a week, and transmit data to the UUSS earthquake information center within seconds of it being recorded.
Many people at the university, and within state and federal agencies, contribute to the success of UUSS. To learn more about all of our partners, and the achievements they have contributed to, please take a few moments to browse through this year’s Annual Report.