Determination of earthquake magnitude using GPS displacement waveforms from real-time precise point positioning
Determination of earthquake magnitude using GPS displacement waveforms from real-time precise point positioning
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利用实时精确单点定位的 GPS 位移波形确定地震震级
DOI：
10.1093/gji/ggt378
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发表时间：
2014-01-01
影响因子：
2.8
通讯作者：
Liu, Jingnan
中科院分区：
文献类型：
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作者：
Fang, Rongxin;Shi, Chuang;Liu, Jingnan
在地震海啸预警和应急响应中，地震震级是必须快速准确确定的关键参数。然而，可靠和快速地测量地震的震级是一个具有挑战性的问题，特别是对于大地震（M > 8）。这里，根据从实时精密单点定位（RTPPP）导出的GPS位移波形来确定幅度。RTPPP结果的水平分量精度为1 cm，垂直分量精度为2-3 cm，表明RTPPP能够检测水平振幅为1 cm，垂直振幅为2-3 cm的地震波，置信度为95%。由GPS位移波形提供的唯一信息是水平峰值位移幅度。结果表明，当用GPS测量位移时，古滕贝格（1945）的峰值位移与震级之间的经验关系可达9.0级。我们测试了三个大地震的方法。对于2010年M-w 7.2 El Mayor-Cucapah地震，我们的方法提供了M7.18 +/- 0.18的震级。对于2011年M-w 9.0的东北冲地震，估计震级为M8.74 +/- 0.06，对于2010年M-w 8.8的Maule地震，排除一些近场台站后的值为M8.7 +/- 0.1。因此，我们的结论是，根据高速率GPS观测的可用性，一个强大的值高达9.0的点源地震可以估计在几十秒或几分钟内使用几个GPS站接近震中的事件发生后。快速震级可以作为海啸预警、快速震源反演和应急响应的前提条件。
For earthquake and tsunami early warning and emergency response, earthquake magnitude is the crucial parameter to be determined rapidly and correctly. However, a reliable and rapid measurement of the magnitude of an earthquake is a challenging problem, especially for large earthquakes (M > 8). Here, the magnitude is determined based on the GPS displacement waveform derived from real-time precise point positioning (RTPPP). RTPPP results are evaluated with an accuracy of 1 cm in the horizontal components and 2-3 cm in the vertical components, indicating that the RTPPP is capable of detecting seismic waves with amplitude of 1 cm horizontally and 2-3 cm vertically with a confidence level of 95 per cent. In order to estimate the magnitude, the unique information provided by the GPS displacement waveform is the horizontal peak displacement amplitude. We show that the empirical relation of Gutenberg (1945) between peak displacement and magnitude holds up to nearly magnitude 9.0 when displacements are measured with GPS. We tested the proposed method for three large earthquakes. For the 2010 M-w 7.2 El Mayor-Cucapah earthquake, our method provides a magnitude of M7.18 +/- 0.18. For the 2011 M-w 9.0 Tohoku-oki earthquake the estimated magnitude is M8.74 +/- 0.06, and for the 2010 M-w 8.8 Maule earthquake the value is M8.7 +/- 0.1 after excluding some near-field stations. We, therefore, conclude that depending on the availability of high-rate GPS observations, a robust value of magnitude up to 9.0 for a point source earthquake can be estimated within tens of seconds or a few minutes after an event using a few GPS stations close to the epicentre. The rapid magnitude could be as a pre-requisite for tsunami early warning, fast source inversion and emergency response is feasible.