Reconciling teleseismic and regional estimates of seismic energy
Reconciling teleseismic and regional estimates of seismic energy
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DOI：
10.1785/0120020212
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发表时间：
2003-10-01
影响因子：
3
通讯作者：
Beroza, GC
中科院分区：
文献类型：
--
作者：
Pérez-Campos, X;Singh, SK;Beroza, GC
根据地震和区域数据对辐射地震能量的估计往往相差一个数量级，对于同一事件，区域估计往往大于地震估计。在这项研究中，我们比较的速度谱确定从地震数据校正后的辐射模式和传播效应，与速度谱确定从区域数据，相应的校正后，9个地震在中美洲俯冲带的墨西哥。校正光谱的这种比较被用来识别和减少区域与地球物理能量差异的来源，这对这些事件来说大约是一个数量级。我们发现，微波衰减算子需要校准。在我们的例子中，对于墨西哥俯冲带的构造环境，我们需要一个在高频下比全球平均值更强的衰减算子。然而，一个更大的因素是考虑位点扩增所需的校正。这一修正对区域数据和地震数据都有影响，但对区域估计值的影响更大，因为地震波的入射角很陡，而且台站位于更坚固的岩石上。通过修改的地震波衰减算子和应用现场校正的基础上，一个通用的网站模型，我们基本上消除了这些事件的辐射地震能量的地震波和区域估计之间的数量级差异。
Estimates of the radiated seismic energy based on teleseismic and regional data often differ by up to an order of magnitude, with a tendency for regional estimates to be larger than teleseismic estimates for the same event. In this study we compare the velocity spectrum determined from teleseismic data after correction for radiation pattern and propagation effects, with the velocity spectrum determined from regional data, after the corresponding corrections, for nine earthquakes in the Middle America subduction zone of Mexico. This comparison of the corrected spectra is used to identify and reduce the sources of the regional versus teleseismic energy discrepancy, which is about an order of magnitude for these events. We find that the teleseismic attenuation operator needs to be calibrated. In our case, for the tectonic environment of the Mexican subduction zone, we need a teleseismic attenuation operator that is stronger at high frequencies than the global average. A larger factor, however, is the correction needed to account for site amplification. This correction has an impact on both regional and teleseismic data, but it has a larger influence on the regional estimates because the angle of incidence for teleseismic waves is steep and the stations are located on more competent rock. By modifying the teleseismic attenuation operator and applying site corrections based on a generic site model, we essentially eliminate the order-of-magnitude discrepancy between teleseismic and regional estimates of the radiated seismic energy for these events.