A hybrid technique for 3-D modeling of high frequency teleseismic body waves in the Earth

摘要

Introduction In the last decade, the deployment of dense regional arrays such as the USArray transportable array has considerably improved our capacity to image the interior of the Earth. However, the use of the wealth, of information coming from these new and large amounts of high quality broadband data still heavily relies on asymptotic approaches. A finite-frequency approach has been used in a few tomographic studies at the regional scale, but for reasons of efficiency sensitivity kernels computed with the asymptotic approach (ray theory) introduced by Dahlen et al. (2000) were used, thus neglecting the near-field effects that are important in the vicinity of stations (Favier et al., 2004). In addition, this asymptotic approach to compute Frechet kernels uses a spherically symmetric reference Earth model. In principle, these shortcomings can be overcome by full-wave approaches, which have been developed recently. However, these methods still suffer from a heavy computational cost, which limits their application to periods larger than a few seconds, even at the regional scale (Tape et al., 2009). Hereafter, we present a numerical method that allows us to model short period teleseismic waves in 3-D media, opening the possibility to perform waveform inversion of seismograms recorded by dense regional broadband arrays.