Developments of Finite-Frequency Seismic Theory and Applications to Regional Tomographic Imaging

摘要

We use 'banana-doughnut' sensitivity kernels of teleseismic body waves to image the crust and mantle beneath eastern Eurasia. We have collected and processed available broadband data from both permanent stations and temporary networks in eastern Eurasia. In southeast Tibet, where a PASSCAL experiment provided a dense station coverage, a detailed study is carried out to obtain high-resolution P- and Svelocity models. A regional P-wave velocity model for eastern Eurasia is also obtained by inverting the finite-frequency traveltimes of teleseismic body waves from available broadband stations in eastern Eurasia. To improve resolution in the crust and uppermost mantle, we have made several contributions to the finite-difference, scattering-integral method (FDSIM), including the finite-frequency sensitivity kernels for head waves and component-dependent sensitivities. We have also developed surface- wave tomography using the ambient seismic noise from 3D sensitivity kernels for finite-frequency Green's functions. We demonstrate that high-resolution tomographic models of the crust and upper mantle can be achieved using finite- frequency teleseismic body waves in places with dense stations, such as southeast Tibet. We show that the continental-scale P velocity model obtained from finite-frequency teleseismic body wave tomography is comparable to that of the high-resolution study in southeast Tibet.