Imaging subducted slab structure beneath the Sea of Okhotsk with teleseismic waveforms

Abstract

The structure of subducted slabs is not well imaged in most global tomographic models with anomalies typically less than 1%. Synthetic waveforms for such models are not noticeably different from their 1D reference models. In contrast, we find that observed teleseismic waveforms sampling slabs in the down-dip direction display multipathing features indicative of substantial structure. Such waveform complexity patterns appear distinctly different for various source locations with outer-rise events generally displaying relatively simple waveforms. Here, we model these waveform patterns for a portion of the Kuril subduction zone. The best fitting slab models have relatively fast cores (∼5%) with smooth edges compatible with thermal modeling in shape. Complete seismograms for these 2D models indicate that multibounce P and S waves are slab-sensitive and can be used in refining models.

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