Seismic Attenuation at High Frequencies in Southern California from Coda Waves Recorded at Depth at Cajon Pass, California

本研究是利用在Cajon Pass钻孔记录的地震数据来研究散射和固有地震衰减的深度和频率依赖关系。以往将散射与本征衰减分离的研究大多假设它们在整个半空间内是恒定的。然而，最近的研究表明，在2.5公里深度处，Qs至少比地表研究预测的要高100倍。对表面低Q层尾波的影响以及与脆性-韧性转变相关的衰减的深度变化将进行研究。这些结果将适用于地震前Q变化的研究和震源研究中使用的路径修正。这项研究是国家减少地震危害计划的一个组成部分。* * * ? ?

9418754 Abercrombie This research is to investigate both the depth and frequency dependence of both scattering and intrinsic seismic attenuation using seismic data recorded at the Cajon Pass borehole. Most of the previous studies separating scattering from intrinsic attenuation assumed that they are constant throughout the half space. However, recent work indicates that at least Qs is about 100 times higher at 2.5 km depth than surface studies have predicted. Effects on coda waves of a low Q layer at the surface and also depth variations of attenuation associated with the brittle-ductile transition will be investigated. The results will apply to studies of variations of Q before earthquakes and to path corrections used in earthquake source studies. This research is a component of the National Earthquake Hazard Reduction Program. *** ??