Radiated Seismic Energy from Very Small and Very Large Earthquakes

对于携带极小地震最多信息的短波来说，地壳中波传播的复杂性使得很难辨别震源造成的影响。多重经验格林函数分析是一种利用极小地震来校正较大地震的复杂波传播效应的方法，当用于这些极小地震时，表明即使在深井记录中也存在意想不到的波传播效应。这可能导致了过去研究中关于极小地震(震级小于2.0级)的能量学的错误结论。这项技术正被应用于一个广泛的数据集，以查看这些结论是否适用于不同环境下的地震：即。南加州的圣安德烈亚斯断层系统和日本变形的地壳。这是一项特别及时的研究，因为钻孔记录中的传播效应可能会影响日本和加利福尼亚州正在进行和计划中的大规模井下实验所获得的测量结果。由东京大学(Satoshi Ide)开发的这项技术正被用于大地震，以从地震的强运动模型确定辐射地震能量的空间分布。对包括1995年日本神户地震在内的一系列三次地震的研究表明，大部分地震能量都是在震源附近辐射的，这表明断裂过程的其余部分基本上是耗散的。这种方法正被应用于更大的可用的扩展震源模型目录，试图更好地理解断裂过程中的能量平衡如何控制地震的大小。

For short wavelengths, which carry the most information for very small earthquakes, the complexity of wave propagation in the Earth's crust makes it difficult to discern effects due to the earthquake source. Multiple empirical Green's function analysis, a method that uses extremely small earthquakes to correct for complicated wave propagation effects for somewhat larger earthquakes, when used for these very small events shows that unanticipated wave propagation effects are present even in deep borehole recordings. This may have led to incorrect conclusions about the energetics of very small (magnitude less than 2.0) earthquakes in past studies. This technique is being applied to an extensive data set in order to see if these conclusions generalize to earthquakes in diverse environments: viz. the San Andreas fault system in southern California and the deforming crust of Japan. This is a particularly timely study because propagation effects in borehole recordings may affect measurements obtained from ongoing and planned large-scale downhole experiments in Japan and in California. The technique developed by Satoshi Ide (University of Tokyo) is being used for large earthquakes, to determine the spatial distribution of radiated seismic energy from strong motion models of the earthquake. Studies of a set of three earthquakes, including the 1995 Kobe, Japan earthquake, shows that most of the seismic energy was radiated near the hypocenter, suggesting that the rest of the faulting process was largely dissipative. This method is being applied to a much larger available catalog of extended-source models in an attempt to improve understanding how the energy balance during faulting controls the size of an earthquake.