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Large-amplitude moho reflections (SmS) from Landers aftershocks, Southern California

Bulletin of the Seismological Society of America

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Abstract

Closely spaced aftershocks of the 28 June 1992 Landers earthquake (Mw 7.3) were used to make event record sections that show the transverse components of 5 and SmS arrivals at a distance of 70 to 170 km. For the data recorded toward the north in the Mojave desert, large SmS phases are observed with amplitudes 2 to 5 times greater than the direct S. For similar distances to the south, the SmS arrival is comparable to or smaller than the S. Comparisons to synthetic seismograms indicate that the large-amplitude SmS phases are produced by the simple crustal structure of the Mojave desert that allows a large Moho reflection. In contrast, the more complex geologic structure to the south partitions the seismic energy into a more complicated set of seismic phases, so that the Moho reflection is diminished in amplitude. The large SmS phases observed in the Mojave enhance the overall ground motions by a factor of 2 to 3. This suggests that when damaging earthquakes occur in other regions of simple crustal structures, Moho reflections will produce amplified strong motions at distance ranges around 100 km depending on the local structure.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Large-amplitude moho reflections (SmS) from Landers aftershocks, Southern California
Series title:
Bulletin of the Seismological Society of America
Volume
86
Issue:
6
Year Published:
1996
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
1845
Last page:
1852
Number of Pages:
8