Microearthquake Imaging of the Parkfield Asperity
Microearthquake Imaging of the Parkfield Asperity
复制标题
帕克菲尔德凹凸体的微地震成像
DOI：
10.1126/science.244.4904.557
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发表时间：
1989
期刊：
影响因子：
56.9
通讯作者：
A. Martin
中科院分区：
文献类型：
--
作者：
P. Malin;S. Blakeslee;M. Alvarez;A. Martin
微地震数据从井下地震仪网络上的圣安德烈亚斯故障似乎概述了两个asepersional凸体，可能对应的前震和主震的帕克菲尔德特征地震的位置。微地震的震源参数表明，少数地震的应力降明显高于大多数地震。此外，震级-频率统计表明，在当地震级0.6，小事件的累积数量开始下降，通常的古腾堡-里希特（B = -1）的关系，其中事件的数量随震级降低呈指数增长。井下地震仪数据建立了一个基线，从该基线可以监测帕克菲尔德地震过程的演变，并表明不同的机械条件比那些导致典型的古腾堡-里克特关系可能是最小的帕克菲尔德微震。
Microearthquake data from a downhole seismometer network on the San Andreas fault appear to outline two aseismic asperities that may correspond to the locations of the foreshocks and main shocks of the Parkfield characteristic earthquakes. The source parameters of the microearthquakes show that a few of the earthquakes have significantly higher stress drops than most. Furthermore, the magnitude-frequency statistics suggest that at local magnitude 0.6, the cumulative number of small events begins to fall off the usual Gutenberg-Richter (b = -1) relation, in which the number of events increases exponentially with decreasing magnitude. The downhole seismometer data establish a baseline from which the evolution of the earthquake process at Parkfield can be monitored and suggest that different mechanical conditions than those that lead to the typical Gutenberg-Richter relation may be operating for the smallest of Parkfield microearthquakes.