Preliminary result of Taiwan 3-D stress field from P wave polarity data
Resource
地球物理學報, 54(11), 2809-2818
Journal
地球物理學報
Journal Volume
54
Journal Issue
11
Pages
2809-2818
Date Issued
2011
Date
2011
Author(s)
Wan, Yong-Ge
We, Yih-Min
Sheng, Shu-Zhong
Shen, Zheng-Kang
Wan, Di
Abstract
We apply the composite focal mechanism method and use more than half million P wave polarity data to invert for the 3 D stress field in Taiwan region. At a given location, composite focal mechanism is estimated using all the P wave polarity data originated from its neighborhood, and the data are weighted using a Gaussian distance weighting function. This method has the advantage of allowing maximum amount of data input in the solution, including polarity data from small earthquakes whose focal mechanisms are undeterminable with too few observation data available.comparing to traditional focal mechanism estimation methods, this method produces focal mechanism estimates covering a broader area, and provides better averages of local focal mechanism solutions. We present the focal mechanism result in a 0. 25° × 0. 25° × 2. 5 km grid in Taiwan and its adjacent areas. The preliminary result shows that the P and T axis directions change markedly across the Moho discontinuity. The P and T axis directions in the 15∼45 km depth range also correlate with P wave velocity perturbations and delineate the northwestward seductions of the Philippine Sea plate in northeast Taiwan. This 3 D stress field result may provide new constraints on geodynamics process in Taiwan region.
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Type
journal article
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