Maximum magnitude (Mmax) in the central and eastern United States for the 2014 U.S. Geological Survey Hazard Model

Bulletin of the Seismological Society of America
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Abstract

Probabilistic seismic‐hazard assessment (PSHA) requires an estimate of Mmax, the moment magnitude M of the largest earthquake that could occur within a specified area. Sparse seismicity hinders Mmax estimation in the central and eastern United States (CEUS) and tectonically similar regions worldwide (stable continental regions [SCRs]). A new global catalog of moderate‐to‐large SCR earthquakes is analyzed with minimal assumptions about enigmatic geologic controls on SCR Mmax. An earlier observation that SCR earthquakes of M 7.0 and larger occur in young (250–23 Ma) passive continental margins and associated rifts but not in cratons is not strongly supported by the new catalog. SCR earthquakes of M 7.5 and larger are slightly more numerous and reach slightly higher M in young passive margins and rifts than in cratons. However, overall histograms of M from young margins and rifts and from cratons are statistically indistinguishable. This conclusion is robust under uncertainties inM, the locations of SCR boundaries, and which of two available global SCR catalogs is used. The conclusion stems largely from recent findings that (1) large southeast Asian earthquakes once thought to be SCR were in actively deforming crust and (2) long escarpments in cratonic Australia were formed by prehistoric faulting. The 2014 seismic‐hazard model of the U.S. Geological Survey represents CEUS Mmax as four‐point probability distributions. The distributions have weighted averages of M 7.0 in cratons and M 7.4 in passive margins and rifts. These weighted averages are consistent with Mmax estimates of other SCR PSHAs of the CEUS, southeastern Canada, Australia, and India.

Publication type Article
Publication Subtype Journal Article
Title Maximum magnitude (Mmax) in the central and eastern United States for the 2014 U.S. Geological Survey Hazard Model
Series title Bulletin of the Seismological Society of America
DOI 10.1785/0120160048
Volume 106
Issue 5
Year Published 2016
Language English
Publisher Seismological Society of America
Contributing office(s) Geologic Hazards Science Center
Description 14 p.
First page 2154
Last page 2167
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