Aftershocks of the 13 May 1993 Shumagin Alaska Earthquake

Authors

Zhong Ludwig, Universtiy of Alaska Fairbanks
Max Wyss, Universtiy of Alaska Fairbanks
Guy Tytgat, Universtiy of Alaska Fairbanks
Stephen R. McNutt, Universtiy of Alaska FairbanksFollow
Scott Stihler, U. S. Geological Survey

Document Type

Article

Publication Date

3-1994

Digital Object Identifier (DOI)

https://doi.org/10.1029/94GL00332

Abstract

The 13 May 1993 M_s 6.9 Shumagin earthquake had an aftershock sequence of 247 earthquakes with magnitudes greater than or equal to 1.5 by 1 June 1993. Of these aftershocks, 79 were located by using S-P travel times at the only two stations within 570 km of the mainshock epicenter. The rupture area inferred from the aftershocks is about 600 km² and we estimate for the mainshock a mean fault displacement of 1.0 m and a 28 bar stress drop. The magnitude-frequency plots give a b-value for the aftershock sequence of about 0.4, which is low compared to the background value of approximately 0.8. The decay of the aftershock sequence followed the modified Omori law with a p-value of 0.79, which is also lower than the typical values of about 1.1 observed in Alaska. Both of these facts can be interpreted as indicating relatively high ambient stress in the Shumagin seismic gap and the possibility that the 13 May earthquake was a foreshock to a larger gap-filling event to occur within the next few years.

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Was this content written or created while at USF?

No

Citation / Publisher Attribution

Geophysical Research Letters, v. 21, issue 6, p. 497-500

Copyright 1994 by the American Geophysical Union.

Scholar Commons Citation

Ludwig, Zhong; Wyss, Max; Tytgat, Guy; McNutt, Stephen R.; and Stihler, Scott, "Aftershocks of the 13 May 1993 Shumagin Alaska Earthquake" (1994). School of Geosciences Faculty and Staff Publications. 265.
https://digitalcommons.usf.edu/geo_facpub/265