| Abstract: | The three-dimensional P and S wave structure of Redoubt Volcano, Alaska, and the underlying crust to depths of 7-8 km is determined from 6219 P wave and 4008 S wave first-arrival times recorded by a 30-station seismograph network deployed on and around the volcano. First-arrival times are calculated using a finite-difference technique, which allows for flexible parameterization of the slowness model and easy inclusion of topography and source-receiver geometry. The three-dimensional P wave velocity structure and hypocenters are determined simultaneously, while the three-dimensional S wave velocity model is determined using the relocated seismicity and an initial S wave velocity model derived from the P wave velocity model assuming an average Vp/Vs ratio of 1.78. Convergence is steady with approximately 73% and 52% reduction in P and S wave arrival time RMS, respectively, after 10 iterations. The most prominent feature observed in the three-dimensional velocity models derived for both P and S waves is a relative low-velocity, near-vertical, pipelike structure approximately 1 km in diameter that extends from 1 to 6 km beneath sea level. This feature aligns axially with the bulk of seismicity and is interpreted as a highly fractured and altered zone encompassing a magma conduit. The velocity structure beneath the north flank of the volcano between depths of 1 and 6 km is characterized by large lateral velocity variations. High velocities within this region are interpreted as remnant dikes and sills and low velocities as regions along which magma migrates. No large low-velocity body suggestive of a magma chamber is resolved in the the upper 7-8 km of the crust. |
| Genre: | Article |
| ProdID: | 70018506 |
| Citation Author: | Benz, H. M.; Chouet, B. A.; Dawson, P. B.; Lahr, J. C.; Page, R. A.; Hole, J. A. |
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| Citation End Page: | 8128 |
| Citation Issue: | 4 |
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| Citation Language: | English |
| Citation Larger Work Title: | Journal of Geophysical Research B: Solid Earth |
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| Citation Number Of Pages: | 18 |
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| Citation Search Results Text: | Three-dimensional P and S wave velocity structure of Redoubt Volcano, Alaska; 1996; Article; Journal; Journal of Geophysical Research B: Solid Earth; Benz, H. M.; Chouet, B. A.; Dawson, P. B.; Lahr, J. C.; Page, R. A.; Hole, J. A. |
| Citation Start Page: | 8111 |
| Citation Volume: | 101 |
| Citation Year: | 1996 |
| Type: | citation/reference |
| Text: | Three-dimensional P and S wave velocity structure of Redoubt Volcano, Alaska; 1996; Article; Journal; Journal of Geophysical Research B: Solid Earth; Benz, H. M.; Chouet, B. A.; Dawson, P. B.; Lahr, J. C.; Page, R. A.; Hole, J. A. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Mon, 1 Jan 1996 00:00 -0600 |
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