Finite-frequency wave propagation through outer rise fault zones and seismic measurements of upper mantle hydration
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Abstract
Effects of serpentine-filled fault zones on seismic wave propagation in the upper mantle at the outer rise of subduction zones are evaluated using acoustic wave propagation models. Modeled wave speeds depend on azimuth, with slowest speeds in the fault-normal direction. Propagation is fastest along faults, but, for fault widths on the order of the seismic wavelength, apparent wave speeds in this direction depend on frequency. For the 5–12 Hz Pn arrivals used in tomographic studies, joint-parallel wavefronts are slowed by joints. This delay can account for the slowing seen in tomographic images of the outer rise upper mantle. At the Middle America Trench, confining serpentine to fault zones, as opposed to a uniform distribution, reduces estimates of bulk upper mantle hydration from ~3.5 wt % to as low as 0.33 wt % H2O.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Finite-frequency wave propagation through outer rise fault zones and seismic measurements of upper mantle hydration |
| Series title | Geophysical Research Letters |
| DOI | 10.1002/2016GL070083 |
| Volume | 43 |
| Issue | 15 |
| Year Published | 2016 |
| Language | English |
| Publisher | AGU Publications |
| Contributing office(s) | Woods Hole Coastal and Marine Science Center |
| Description | 9 p. |
| First page | 7982 |
| Last page | 7990 |
| Google Analytic Metrics | Metrics page |