| Abstract: | A reverse-right-oblique surface rupture, associated with a ML 2.5 earthquake, formed in a diatomite quarry near Lompoc, California, in the northwesternmost Transverse Ranges on April 7, 1981. The 575-m-long narrow zone of ruptures formed in clay interbeds in diatomite and diatomaceous shale of the Neogene Monterey Formation. The ruptures parallel bedding, dip 39o-59oS, and trend about N84oE on the north limb of an open symmetrical syncline. Maximum net slip was 25 cm; maximum reverse dip slip was 23 cm, maximum right-lateral strike slip was about 9 cm, and average net slip was about 12 cm. The seismic moment of the earthquake is estimated at 1 to 2 X 1018 dyne/cm and the static stress drop at about 3 bar. The removal of an average of about 44 m of diatomite resulted in an average load reduction of about 5 bar, which decreased the normal stress by about 3.5 bar and increased the shear stress on the tilted bedding plane by about 2 bar. The April 7, 1981, event was a very shallow bedding-plane rupture, apparently triggered by crustal unloading. -Authors |
| Genre: | Article |
| ProdID: | 70011287 |
| Citation Author: | Yerkes, R. F.; Ellsworth, W. L.; Tinsley, J. C. |
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| Citation End Page: | 291 |
| Citation Issue: | 5 |
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| Citation Language: | English |
| Citation Larger Work Title: | Geology |
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| Citation Number Of Pages: | 5 |
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| Citation Search Results Text: | Triggered reverse fault and earthquake due to crustal unloading, northwest Transverse Ranges, California.; 1983; Article; Journal; Geology; Yerkes, R. F.; Ellsworth, W. L.; Tinsley, J. C. |
| Citation Start Page: | 287 |
| Citation Volume: | 11 |
| Citation Year: | 1983 |
| Type: | citation/reference |
| Text: | Triggered reverse fault and earthquake due to crustal unloading, northwest Transverse Ranges, California.; 1983; Article; Journal; Geology; Yerkes, R. F.; Ellsworth, W. L.; Tinsley, J. C. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Sat, 1 Jan 1983 00:00 -0600 |
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