Seismic anisotropy of the shallow crust at the Juan de Fuca Ridge
Geophysical Research Letters
By: J. Almendros, A.H. Barclay, W.S.D. Wilcock, and G.M. Purdy
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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.
Suggested Citation
Almendros, J., Barclay, A., Wilcock, W., and Purdy, G., 2000, Seismic anisotropy of the shallow crust at the Juan de Fuca Ridge: Geophysical Research Letters, v. 27, no. 19, p. 3109-3112, https://doi.org/10.1029/2000GL011535.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Seismic anisotropy of the shallow crust at the Juan de Fuca Ridge |
| Series title | Geophysical Research Letters |
| DOI | 10.1029/2000GL011535 |
| Volume | 27 |
| Issue | 19 |
| Year Published | 2000 |
| Language | English |
| Publisher | American Geophysical Union |
| Description | 4 p. |
| First page | 3109 |
| Last page | 3112 |
| Other Geospatial | Juan de Fuca Ridge, Pacific Ocean |