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Pre-earthquake displacement and triggered displacement on the Imperial fault associated with the Superstition Hills earthquake of 24 November 1987

Bulletin of the Seismological Society of America

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Abstract

Two right-lateral slip events, about 3 weeks apart in November 1987, broke the surface discontinuously along probably similar, nearly 20km lengths of the northern Imperial fault. The first displacement, at about the beginning of November, was accompanied by a surface tilt representing deep vertical motion or distributed strain. The later surface offset was triggered, probably by the second main shock of the 24 November earthquakes located in the Superstition Hills, about 37km northwest of the Imperial fault. Pre-earthquake resurveys of short-length leveling lines indicated combined surface displacement and an eastward tilt at two locations between surveys 7 1/2 months apart and 13 months apart; the tilt at Harris Road during this pre-earthquake interval is modeled as a 1.4cm vertical component of slip deeper than 100m on a 70?? northeastward-dipping fault. Later surveys showed a marked reduction of deep movement in the time period including the triggered slip, and between December 1987 and January 1988, it had ceased. No definite evidence of surface fracturing was found in the Brawley fault zone during either period of time when the Imperial fault moved. -from Authors

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Pre-earthquake displacement and triggered displacement on the Imperial fault associated with the Superstition Hills earthquake of 24 November 1987
Series title:
Bulletin of the Seismological Society of America
Volume
79
Issue:
2
Year Published:
1989
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Bulletin of the Seismological Society of America
First page:
466
Last page:
479