What do we know and don’t know about high frequency radiation from a large earthquake?

韦生吉 博士

南洋理工大学 亚洲环境学院

2022.04.29（星期五）15:00，腾讯会议号：641-759-280

报告摘要：

  Earthquakes is a multi-scale shear dislocation process on a fault(s) that radiated seismic waves in a wide range of spectrum. Well-constrained rupture process of a large earthquake is critical for understanding its fundamental physics and subsequently better preparing for future damaging events. Back-projection (BP) of teleseismic array waveforms to image the spatial and temporal process of an earthquake is an important approach towards this goal. However, the sources of uncertainties in BP results have rarely been systematically investigated, and the boundaries of knowledge gaps in BP studies have not yet been clearly drawn. To this end, we use synthetic tests along with real cases to investigate the impact of source depth, focal mechanisms, and the Earth's 3-D velocity structures to the uncertainties in BP results. With a better understanding of BP uncertainties, we use travel-time data of teleseismic events recorded by the Hi-Net array to reveal how travel-time errors vary with source location. We then propose a new interpolation scheme using earthquakes located around the mainshock rupture to calibrate the travel-time error due to the source-side 3D velocity structure. The new calibration scheme is validated by applications in Japan, the 2002 Denali earthquake and the 2021 Maduo earthquake, which have revealed several unique features of the rupture processes. Finally, some potentials and challenges in high frequency earthquake source studies are discussed.

报告人简介：

韦生吉博士是新加坡南洋理工大学亚洲环境学院助理院长（科研）和助理教授，也是新加坡地球观测站研究员。博后阶段工作于美国加州理工学院地震学实验室。于2004年和2009年在中国科技大学获得地球物理学学士和博士学位。韦生吉博士目前担任《Bulletin of the Seismological Society of America》和《Geoscience Letters》副编辑，《Tectonophysics》,《Earthquake Science》编委会成员，并担任《Science》、《Earth and Planetary Science Letters》等期刊审稿人，已在学术期刊上发表论文80余篇。他的研究重点是震源观测、震源物理、地下结构成像及其震源构造和地球动力学解释，以及火山地震和东南亚地震学。