Epicentral location based on Rayleigh wave Empirical Green's Functions from ambient seismic noise
Epicentral location based on Rayleigh wave Empirical Green's Functions from ambient seismic noise
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DOI：
10.1111/j.1365-246x.2010.04879.x
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发表时间：
2011-02
影响因子：
2.8
通讯作者：
M. P. Barmin;A. Levshin;Yingjie Yang;M. Ritzwoller
中科院分区：
文献类型：
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作者：
M. P. Barmin;A. Levshin;Yingjie Yang;M. Ritzwoller
发明内容 开发了一种定位区域地震事件震中的新方法，其优点和局限性与现有定位方法互补。这项新技术基于对 7 至 15 秒周期之间的瑞利波应用经验格林函数 (EGF)，该函数是由地震接收器对记录的环境噪声时间序列的互相关确定的。与基于使用体波走时的标准程序相比，该方法的重要优点是它不依赖于地球模型。相反，它基于将 EGF 插值到任意假设的事件位置。该方法通过定位美国西部众所周知的“地面真相”地壳事件（加利福尼亚州的 4 级地震、犹他州的 3 级地震和矿井塌方）以及将地震台定位为虚拟事件来进行测试。在这些应用中，定位误差平均小于 1 公里，但预计会随事件机制和深度而变化。数值模拟表明，当震源深度小于1 km或大于5 km，且震源机制接近纯走滑、逆冲或法向时，该方法最为优化。
SUMMARY A new method to locate the epicentre of regional seismic events is developed with strengths and limitations complementary to existing location methods. This new technique is based on applying empirical Green's functions (EGFs) for Rayleigh waves between 7 and 15 s period that are determined by cross-correlation of ambient noise time-series recorded at pairs of seismic receivers. The important advantage of this method, in comparison with standard procedures based on use of body wave traveltimes, is that it does not rely on an earth model. Rather it is based on interpolating the EGFs to arbitrary hypothetical event locations. The method is tested by locating well known ‘Ground Truth' crustal events in the western United States (magnitude 4 earthquakes in California, magnitude 3 earthquakes in Utah, and a mine collapse) as well as locating seismic stations as virtual events. In these applications, location errors average less than 1 km, but are expected to vary with event mechanism and depth. Numerical simulations show that the method optimizes when source depth is less than 1 km or more than 5 km, and when the source mechanism is nearly purely strike-slip, thrust or normal.