| Abstract: | Microearthquake data recorded on four ocean bottom seismometers are used to study shear-wave splitting on the Endeavour Segment of the Juan de Fuca Ridge. The covariance matrix decomposition method is used to determine the sensor orientation from explosive shot data and to estimate the anisotropy parameters for 238 earthquake records. At three of the four sites, the results show a remarkably consistent fast direction parallel to the ridge axis. The time delays between the fast and the slow waves range from 40 to 200 ms, with an average of 90 ms. They are not clearly related to earthquake range, focal depth or source-receiver azimuth. The splitting of the shear waves is interpreted as an effect of structural anisotropy due to the presence of ridge-parallel cracks in the shallow crust. If we assume that anisotropy is concentrated in the upper 1-2 km, the splitting times require a high crack density of ~0.1. |
| Genre: | Article |
| ProdID: | 70022060 |
| Citation Author: | Almendros, J.; Barclay, A. H.; Wilcock, W. S. D.; Purdy, G. M. |
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| Citation End Page: | 3112 |
| Citation Issue: | 19 |
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| Citation Language: | English |
| Citation Larger Work Title: | Geophysical Research Letters |
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| Citation Number Of Pages: | 4 |
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| Citation Search Results Text: | Seismic anisotropy of the shallow crust at the Juan de Fuca Ridge; 2000; Article; Journal; Geophysical Research Letters; Almendros, J.; Barclay, A. H.; Wilcock, W. S. D.; Purdy, G. M. |
| Citation Start Page: | 3109 |
| Citation Volume: | 27 |
| Citation Year: | 2000 |
| Type: | citation/reference |
| Text: | Seismic anisotropy of the shallow crust at the Juan de Fuca Ridge; 2000; Article; Journal; Geophysical Research Letters; Almendros, J.; Barclay, A. H.; Wilcock, W. S. D.; Purdy, G. M. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Sat, 1 Jan 2000 00:00 -0600 |
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