Teleseismic P-wave crustal tomography of the Weifang segment on the Tanlu fault zone: A case study based on short-period dense seismic array experiment

Abstract

The 1896 high-quality relative travel-time residuals are collected by applying the Multi-Channel Cross-Correlation technique to the waveform data of teleseismic events recorded by a short-period dense seismic array consisting of 302 stations in the Weifang segment of the Tanlu fault zone. Using the Fast Marching Teleseismic Tomography technique, these residuals are inverted for a fine P-wave crustal velocity model under the study region down to 30 km depth with the resolution of ~20 km in horizontal directions and ~30 km in depth. We image obvious high-velocity anomalies to the west of the fault zone from the surface down to a depth of 30 km, and striking low-velocity anomalies appear within the fault zone around 36.5°N where the Changle volcano exists on the surface, whilst to the east velocity anomalies exhibit a complicated pattern. Meanwhile, our tomographic images roughly show a boundary between the fault zone and its surrounding areas. We infer that the fault zone provides a plausible channel for continuous upwelling of hot and wet materials from the mantle to the surface when it intruded into the crust. The process of upwelling of hot and wet materials from the mantle could be associated with mantle dynamics of the big mantle wedge due to the stagnation and dehydration of the subducted Pacific slab in the mantle transition zone under the region. Our present study demonstrates that it is possible that a fine crustal velocity structure can be obtained by teleseismic tomography with a short-period dense seismic array.