Title：Real-time GNSS for tsunami early warning：from lithosphere to ionosphere

speaker：Dr. Kejie Chen

邀请人：李星星 教授

时间：2017年6月2日上午9：30-11：00

地点：3044am永利集团3044noc218会议室

Abstract：

Over the past decades, rapid and constant advances have motivated GNSS technology to approach the ability to monitor transient ground motions with mm to cm accuracy in real-time. Compared with seismic method, GNSS receivers never clip, which is specially valuable for fast determination of mega-thrust earthquake size and corresponding tsunami early warning. In addition, GNSS observables can be used to compute the ionospheric total electron content (TEC) to measure, model, and monitor postseismic ionospheric disturbances caused by earthquakes/tsunamis.

In this contribution,we review new algorithms to get precise co-seismic displacements using either only GNSS raw observations or GNSS/strong motion combinations, then present seismic source inversion tools which make use of GNSS static offsets or displacement waveforms. Take the March 2011 Tohuku-Oki as an example, tsunami scenarios are synthesised based on slip distribution inverted from GNSS. After that, by employing a three-dimensional physics-based model Wave Perturbation-Global Ionosphere-Thermosphere, the simulated TEC perturbations agree with GNSS observations reasonably well. For the first time, GNSS observations show a fully self-consistent applications to tsunami early warning from lithosphere to ionosphere.

About the speaker：

Kejie Chen is currently a postdoc researcher at Caltech, and his research focuses on GNSS data processing, GNSS/strong motion data combination, earthquake rupture inversion using geodetic and geophysical data, and earthquake/tsunami early warning. He got his master degree of geodesy from Wuhan University in 2012 and PhD degree of geophysics from GFZ/Potsdam University in Germany in 2016. During his PhD time, he worked as a research assistant at GFZ (2015-2016) and a visiting scholar at University of California, Berkeley (2016). His peer-reviewed papers were published in Geophysical Research Letters, Geophysical Journal International and etc al., and he is also a reviewer for Bulletin of the Seismological Society of America and Advances in Space Research and et al.

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