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，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的影响。 多个经验绿色函数分析，一种方法，使用非常小的地震，以纠正复杂的波传播的影响，稍微大一些的地震，当用于这些非常小的事件表明，意想不到的波传播的影响，即使在深钻孔记录。 这可能导致过去研究中关于非常小（震级小于2.0）地震能量学的错误结论。 这项技术正在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中的地震：即，在南加州的圣安德烈亚斯断层系统和日本的地壳变形。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州正在进行和计划进行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，以确定地震强震模型辐射地震能量的空间分布。 对包括1995年日本科比地震在内的三次地震的研究表明，大部分地震能量都辐射到了震源附近，这表明断裂过程的其余部分在很大程度上是耗散的。 这种方法正被应用于一个更大的扩展源模型的可用目录，试图提高理解断层作用期间的能量平衡如何控制地震的大小。