Abstract

In 2008, the TAiwan Integrated GEodynamics Research (TAIGER) project conducted an active-source experiment in which seismic records from 10 explosions were collected at nearly 1400 locations on the island of Taiwan. We use the first-arrival times manually picked from the explosion records to examine the P-wave travel-time variations resulting from the complex crust and uppermost mantle structures beneath Taiwan. Distributions of the observed first-arrival times exhibit characteristic patterns associated with vertical and lateral velocity variations present in different tectonic domains in the region. Aided by numerical simulations, we compare the observed first-arrival times with those predicted from a one-dimensional (1D) model and three three-dimensional (3D) tomography models for Taiwan that portray the underlying variations in seismic wave speeds frequently utilized to decipher the regional tectonic framework in Taiwan. We evaluate the quality of the four models by the goodness of fit between the observed and model-predicted travel times that demonstrates significant improvement of the 3D models over the 1D model. Statistical distributions of the differential travel-time residuals allow us to inspect quantitatively the overall effectiveness of these models in replicating the observed ground-truth first-arrival times so as to make an assessment of the strength and deficiency of the resolved velocity structures that agree with or contradict the travel-time observations from the explosion experiment.

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