Crust and Upper Mantle Structure from Joint Inversion of Body Wave and Gravity Data (Postprint). Annual Report 1.

摘要

We are investigating the crustal and upper mantle velocity structure of the region expressing the continental collision between the Arabian and Eurasian plates using a joint inversion of body wave arrival times and satellite gravity. The body wave data set is derived from previous and on-going work on location calibration and includes a large (approx. 1700 events) subset of events that qualify as GT590. The associated arrival time data sets for these events include many readings of direct crustal P and S phases, as well as regional (Pn and Sn) and teleseismic phases. The data set has been carefully groomed to identify and remove outlier readings and empirical reading errors are estimated for most arrivals from a multiple event relocation analysis. The gravity data provides valuable supplemental information on the lateral distribution of velocity variations that helps to compensate for incomplete raypath coverage in the body waveform data set, especially when bandpass filtering is used to constrain the gravity signal to depth ranges that are consistent with the body wave data. We will carry out experiments with smaller, higher-quality GT data sets as well as full data sets that include all available arrival time data in the region, and try to determine if the increase in precision and accuracy of GT-derived data adequately compensates for reduced numbers of data and raypaths. We will compare our results on lateral heterogeneity of the crust and upper mantle velocities in this region with other studies and offer our results for integration into Lab-based research efforts to construct improved 3-D velocity models to support monitoring efforts in the region.