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A Unified Approach to Joint Regional/Teleseismic Calibration and Event Location with a 3D Earth Model

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Conference paper

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This newly initiated project will develop and test a methodology for locating seismic events from combined data sets of regional and teleseismic arrival times, based on consistent travel-time predictions from a unified 3D Earth model. One focus of the project is to address the practical difficulty of raytracing in 3D models, which has been a serious impediment to the pursuit of 3D event location methods. We will investigate whether, for teleseismic travel-time prediction, approximate techniques, in particular linearization around rays calculated in a 1D reference model, are adequate for the purpose of event location as they are commonly assumed to be for the purpose of global tomography. A second focus of the project is tomographic calibration of a 3D model with combined regional and teleseismic data from earthquakes and ground-truth events. We will investigate the hypothesis that a joint regionalteleseismic calibration will lead to a noticeable improvement in location accuracy over the modest and inconsistent improvements 3D models have yielded to date. Additionally, we will consider whether travel-time prediction errors inferred from a tomographic uncertainty analysis can provide an appropriate weighting of various teleseismic and regional phases to optimize location accuracy even further. We plan to validate our methodology with catalog data from Asia, the Middle East and North Africa, using available regional crustupper mantle models for these areas in conjunction with published 3D global models of the deeper mantle. Special attention will be given to south-central Asia, where Weston Geophysical and MIT are currently applying body-wave and surface-wave tomography to develop a regional model of the crust and upper mantle. This project will attempt to improve and extend the WestonMIT model by adding teleseismic constraints.

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  • Cartography and Aerial Photography
  • Geology, Geochemistry and Mineralogy
  • Seismology

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