Performance Test of First Body-Wave Arrival Times for Constraining a Slow Mantle Wedge in a Subduction Zone
Abstract
Based on numerical experiments, this study tests how much seismic wave speeds of a slow mantle wedge can be constrained by using first arrival times of body waves in 3-D traveltime tomography. In a subduction zone, dehydration reactions of rocks can occur within a subducting oceanic plate, depending on the pressure and temperature. Water from the reactions can move further to the overriding crust or mantle, possibly causing hydration reactions. As water and its metamorphic reactions affect seismic wave speeds of rocks, seismic tomography, which can estimate wave speeds, is a popular technique to explore the distribution of water and associated reactions in and around the descending plate. Nevertheless, the technique could not be perfect. Data utilized in many studies of tomography are first arrival times of P and S waves. When there is a low velocity region, the first arrivals do not always involve waves traversing the slow region. In this study, we examine how much wave speeds can be apparently changed by using first arrival-time data, particularly, in a subduction region where the mantle wedge is slow. Our numerical experiments show that a slow mantle wedge can be constrained by arrival times of body waves traveling along multiple paths. When only first arrival times are used, however, the wave speeds estimated for the mantle wedge can be unstably higher in a homogeneous station distribution.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.S41A2723K
- Keywords:
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- 3260 Inverse theory;
- MATHEMATICAL GEOPHYSICSDE: 3275 Uncertainty quantification;
- MATHEMATICAL GEOPHYSICSDE: 7270 Tomography;
- SEISMOLOGYDE: 7290 Computational seismology;
- SEISMOLOGY