Arabasz

Earthquake database for Utah Geological Survey Map 277: Utah earthquakes (1850–2016) and Quaternary faults: Utah Geological Survey Open-File Report 667

Posted on by Paul Roberson

The Utah Geological Survey (UGS), University of Utah Seismograph Stations (UUSS), and Utah Division of Emergency Management (UDEM) recently published the Utah Earthquakes (1850–2016) and Quaternary Fault Map (UGS Map 277). The new map shows earthquakes within and surrounding Utah from 1850 to 2016, and faults considered to be sources of large earthquakes.

Utah Earthquakes (1850-2016) and Quaternary Faults

 

The faults shown on the map are considered geologically active, have been sources of large earthquakes (about magnitude 6.5 and greater) during the Quaternary Period (past 2.6 million years), and are the most likely sources of large earthquakes in the future. Most of the small to moderate-sized earthquakes on the map are “background” earthquakes not readily associated with known faults and too small to have triggered surface faulting (under about magnitude 6.5).

 

There is a 57% probability (over 1 in 2 chance) that a magnitude 6.0 or greater earthquake will occur in the Wasatch Front region in the next 50 years. To address this threat, the Utah Earthquake Program, consisting of the UGS, UUSS, and the UDEM, developed the map so the public could more fully understand the hazard from earthquakes and faults, as well as the resulting risk to property, infrastructure, and life safety in Utah. Users of the map will be able to determine past earthquake locations and relative magnitudes (size), along with the locations of active faults and the timing of their most recent movement.

 

Printed copies of the map are available for $15 at the Utah Department of Natural Resources Map & Bookstore. The map is also available as a PDF download at https://ugspub.nr.utah.gov/publications/maps/m-277.pdf (44 by 62 inches in size) and can be printed on a wide-format printer.

The database for the seismicity plotted on the map, together with explanatory information, is provided in a companion report:
Arabasz, W. J., Burlacu, R., and Pechmann, J. C., 2017, Earthquake database for Utah Geological Survey Map 277: Utah earthquakes (1850–2016) and Quaternary faults: Utah Geological Survey Open-File Report 667, 12 p. plus 4 electronic supplements, available as a PDF download.
The electronic supplements include the data for the seismic events plotted on the map, which are listed in two separate catalogs, each in the form of a Microsoft Excel workbook and an ArcGIS feature class within a file geodatabase. The catalog files are available for download.

Origins of a National Seismic System in the United States

Posted on by Paul Roberson

Origins of a National Seismic System in the United States

John R. Filson, Walter J. Arabasz

Seismological Research Letters Nov 2016, DOI: 10.1785/0220160039

ABSTRACT

This historical review traces the origins of the current national seismic system in the United States, a cooperative effort that unifies national, regional, and local-scale seismic monitoring within the structure of the Advanced National Seismic System (ANSS). The review covers (1) the history and technological evolution of U.S. seismic networks leading up to the 1990s, (2) factors that made the 1960s and 1970s a watershed period for national attention to seismology, earthquake hazards, and seismic monitoring, (3) genesis of the vision of a national seismic system during 1980–1983, (4) obstacles and breakthroughs during 1984–1989, (5) consensus building and convergence during 1990–1992, and finally (6) the twostep realization of a national system during 1993–2000. Particular importance is placed on developments during the period between 1980 and 1993 that culminated in the adoption of a charter for the Council of the National Seismic System (CNSS)—the foundation for the later ANSS. Central to this story is how many individuals worked together toward a common goal of a more rational and sustainable approach to national earthquake monitoring in the United States. The review ends with the emergence of ANSS during 1999 and 2000 and its statutory authorization by Congress in November 2000.

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)

Posted on by Paul Roberson

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

Posted on by Paul Roberson
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.

Former UUSS Director, Dr. Walter J. Arabasz, Honored by the Seismological Society of America

Posted on by Sheryl Peterson

Dr. Walter J. Arabasz, Research Professor Emeritus of Geology and Geophysics and forWJA web photomer director of the University of Utah Seismograph Stations, will be presented with the Seismological Society of America (SSA) 2015 Frank Press Public Service Award for his extraordinary public service in modernizing, expanding and promoting seismic monitoring for public safety in the United States. The award will be presented during the SSA annual meeting in Reno, Nevada, April 20–22, 2016.

The Frank Press Public Service Award is presented each year to an individual, group of individuals, or organization that has made outstanding contributions to the advancement of public safety or public information relating to seismology.

Dr. Arabasz began his career at the University of Utah in 1974 and was appointed director of the University of Utah Seismograph Stations in 1985, a position he held until his retirement from university in 2010.

He played a leading role in motivating the Utah State Legislature to create the Utah Seismic Safety Commission and in helping to build an effective state earthquake program.

During a 15-year period leading up to congressional authorization of the Advanced National Seismic System (ANSS) in 2000, Dr. Arabasz was a key player in laying the groundwork for and shaping the vision of the ANSS. He then worked to implement elements of the ANSS in Utah, in the Intermountain West region, and nationally. He has served on the national Advisory Committee on Earthquake Hazards Reduction, providing guidance and oversight to the National Earthquake Hazards Reduction Program.

Of particular note in his award nominations was Dr. Arabasz’s efforts following the 2007 Crandall Canyon, Utah mine collapse. Dr. Arabasz assisted experts on both the state and national levels to reach a better understanding of the circumstances of the collapse and the implications for the larger issue of mine safety. He also assisted the media and public in gaining a greater awareness and understanding of mining-induced seismicity.

A uniform moment magnitude earthquake catalog for the Utah region (1850–2012) and estimation of unbiased recurrence parameters for background seismicity

Posted on by Paul Roberson
Arabasz, W. J., J. C. Pechmann, and R. Burlacu (2015). A uniform moment magnitude earthquake catalog for the Utah region (1850–2012) and estimation of unbiased recurrence parameters for background seismicity, 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

Posted on by Paul Roberson
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.

Ground-motion recording and analysis of mining-induced seismicity in the Trail Mountain Area, Emery County, Utah

Posted on by Paul Roberson

Arabasz, W.J., S.J. Nava, M. k. McCarter, and K. L. Pankow (2002) Ground-motion recording and analysis of mining-induced seismicity in the Trail Mountain Area, Emery County, Utah, technical Report, University of Utah Seismograph Stations, Salt Lake City, Utah, 162pp.