Radiated Seismic Energy from Very Small and Very Large Earthquakes

非常小和非常大的地震辐射的地震能量

• 批准号: 0208499
• 负责人: Gregory Beroza
• 金额: $ 22.44万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2006-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0208499&HistoricalAwards=false
• 关键词: Radiated; Seismic; Energy; Very; Small

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.

对于短波长来说，它携带了非常小的地震的大部分信息，地壳中波传播的复杂性使得很难辨别地震源造成的影响。 多重经验格林函数分析是一种使用极小地震来校正较大地震的复杂波传播效应的方法，当用于这些非常小的事件时，表明即使在深井记录中也存在意外的波传播效应。 这可能导致过去的研究对极小（震级小于2.0）地震的能量学得出错误的结论。 该技术正在应用于广泛的数据集，以便查看这些结论是否适用于不同环境中的地震：即。加利福尼亚州南部的圣安德烈亚斯断层系统和日本地壳变形。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从日本和加利福尼亚正在进行和计划的大规模井下实验中获得的测量结果。 Satoshi Ide（东京大学）开发的技术正用于大地震，从地震的强运动模型中确定辐射地震能量的空间分布。 对三场地震（包括 1995 年日本神户地震）的研究表明，大部分地震能量在震源附近辐射，这表明其余的断层过程在很大程度上是耗散的。 该方法正被应用于更大的可用扩展源模型目录，以试图加深对断层作用期间的能量平衡如何控制地震规模的理解。