Estimating Local Vp/Vs ratios within Similar Earthquake Clusters in Taiwan Region
Date Issued
2014
Date
2014
Author(s)
Huang, Han-Yu
Abstract
In general, variations in Vp/Vs ratios may be determined by using tomographic methods. However, the resolution of local Vp/Vs ratios from tomography is usually limited due to the coarse grid sizes and the regularization operation. Lin and Shearer (2007) proposed that the Vp/Vs ratios could also be estimated within similar earthquake clusters from measuring the P and S differential arrival times with waveform cross-correlation. This technique potentially has higher resolution than typical tomographic inversion method. Benefited by the dense seismic network and high seismicity, Taiwan region is very suitable place for applying this approach to determine Vp/Vs. But the complexity of the geological structure in Taiwan is very different from the Southern California. To consider the effect of different parameter and factor on this new method, synthetic test is used on the similar earthquake cluster in Taiwan region to examine this approach. Also, a robust misfit function method is modified from the previous study to compute Vp/Vs ratios for both synthetic datasets and similar earthquake clusters. In comparison with the results from the latest tomographic model, Vp/Vs ratio of one cluster(Jiaxian area) is very consistent with our result. On the other hand, Vp/Vs ratio of another cluster(Hualian area) is very different from tomographic model. It may indicate the different resolution between two methods, in which, conventional tomographic method may not be able to resolve small scale of heterogeneity. Furthermore, data processing in this study may be used to estimate Vp/Vs ratio for further study or future work in different area.
Subjects
台灣
Vp/Vs值
差分時間
相似地震群
波形交叉相關法
Type
thesis
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