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Depth Discrimination Using Rg‐to‐Sg Spectral Amplitude Ratios for Seismic Events in Utah Recorded at Local Distances

2018; Seismological Society of America; Volume: 108; Issue: 3A Linguagem: Inglês

10.1785/0120170257

1943-3573

Rigobert Tibi, Keith D. Koper, K. L. Pankow, Christopher J. Young,

Seismic Waves and Analysis

Research Article| March 20, 2018 Depth Discrimination Using Rg‐to‐Sg Spectral Amplitude Ratios for Seismic Events in Utah Recorded at Local Distances Rigobert Tibi; Rigobert Tibi aSandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185‐0404, rtibi@sandia.gov Search for other works by this author on: GSW Google Scholar Keith D. Koper; Keith D. Koper bDepartment of Geology and Geophysics, University of Utah, 115 South 1460 East, Salt Lake City, Utah 84112 Search for other works by this author on: GSW Google Scholar Kristine L. Pankow; Kristine L. Pankow bDepartment of Geology and Geophysics, University of Utah, 115 South 1460 East, Salt Lake City, Utah 84112 Search for other works by this author on: GSW Google Scholar Christopher J. Young Christopher J. Young aSandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185‐0404, rtibi@sandia.gov Search for other works by this author on: GSW Google Scholar Author and Article Information Rigobert Tibi aSandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185‐0404, rtibi@sandia.gov Keith D. Koper bDepartment of Geology and Geophysics, University of Utah, 115 South 1460 East, Salt Lake City, Utah 84112 Kristine L. Pankow bDepartment of Geology and Geophysics, University of Utah, 115 South 1460 East, Salt Lake City, Utah 84112 Christopher J. Young aSandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185‐0404, rtibi@sandia.gov Publisher: Seismological Society of America First Online: 20 Mar 2018 Online Issn: 1943-3573 Print Issn: 0037-1106 © Seismological Society of America Bulletin of the Seismological Society of America (2018) 108 (3A): 1355–1368. https://doi.org/10.1785/0120170257 Article history First Online: 20 Mar 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Rigobert Tibi, Keith D. Koper, Kristine L. Pankow, Christopher J. Young; Depth Discrimination Using Rg‐to‐Sg Spectral Amplitude Ratios for Seismic Events in Utah Recorded at Local Distances. Bulletin of the Seismological Society of America 2018;; 108 (3A): 1355–1368. doi: https://doi.org/10.1785/0120170257 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyBulletin of the Seismological Society of America Search Advanced Search Abstract Short‐period fundamental‐mode Rayleigh waves (Rg) are commonly observed on seismograms of anthropogenic seismic events and shallow, naturally occurring tectonic earthquakes (TEs) recorded at local distances. In the Utah region, strong Rg waves traveling with an average group velocity of about 1.8 km/s are observed at ∼1 Hz on waveforms from shallow events (⁠depth<10 km⁠) recorded at distances up to about 150 km. At these distances, Sg waves, which are direct shear waves traveling in the upper crust, are generally the dominant signals for TEs. In this study, we leverage the well‐known notion that Rg amplitude decreases dramatically with increasing event depth to propose a new depth discriminant based on Rg‐to‐Sg spectral amplitude ratios. The approach is successfully used to discriminate shallow events (both earthquakes and anthropogenic events) from deeper TEs in the Utah region recorded at local distances (⁠<150 km⁠) by the University of Utah Seismographic Stations (UUSS) regional seismic network. Using Mood’s median test, we obtained probabilities of nearly zero that the median Rg‐to‐Sg spectral amplitude ratios are the same between shallow events on the one hand (including both shallow TEs and anthropogenic events), and deeper earthquakes on the other, suggesting that there is a statistically significant difference in the estimated Rg‐to‐Sg ratios between the two populations. We also observed consistent disparities between the different types of shallow events (e.g., mining blasts vs. mining‐induced earthquakes), implying that it may be possible to separate the subpopulations that make up this group. This suggests that using local distance Rg‐to‐Sg spectral amplitude ratios one can not only discriminate shallow events from deeper events but may also be able to discriminate among different populations of shallow events. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.