Delineating seismogenic structures by a revised best estimate method: application to the Taiwan orogenic belt |
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| Authors: | Wen-Nan Wu Li Zhao |
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| Institution: | 1. Institute of Earth Sciences, Academia Sinica, 128, Sec. 2, Academia Road, Nangang, Taipei 11529, Taiwan
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| Abstract: | The best estimate method (BEM), which shifts an object event towards the centroid of the events within its location uncertainty, was originally proposed to clarify the pattern of seismicity distribution. It was later widely applied to constrain the location and geometry of seismogenic structures. The goal of this study is to improve the efficiency, robustness and effectiveness of the BEM. We perform a series of synthetic experiments by generating a three-dimensional (3D) event dataset representing complex tectonic features and perturbing the presumed hypocenter locations. The synthetic experiments show that appropriate expression for the location uncertainty of the object event and restrictive thresholds of the event selection can significantly improve the collapsing seismicity image. We also demonstrate that the performance of our revised BEM (RBEM) is better than that of the original BEM. We then apply our RBEM to the seismicity catalog for the Taiwan region, collapsing the diffusive catalog hypocenters into sharp images of seismicity. Our RBEM result delineates a clearer low-seismicity zone in central Taiwan and a wider separation between the Wadati–Benioff double seismic layers in northeastern Taiwan than the corresponding features in either the catalog seismicity or the 3D relocation seismicity. Because of the simplicity and efficiency of the RBEM, it is perfectly suited to delineate the location and geometry of active faults in routine operations. |
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