Massive Microearthquake Relocation: Technique Development and Application to Seismotectonics

这项研究涉及将精确的地震定位方法扩展到大量事件以及火山和活动断裂带内更多样化的构造框架。1989年加利福尼亚州洛马普里塔地震后的工作已经开始。在主震的东南部，沿着向南的圣安德烈亚斯爬行部分的过渡，超过60%的地震人口的重新定位表明，大部分地震活动集中在线性的、近水平的带状区域中，这些带状区域被推测为主要以地震方式滑动的区域隔开。这与早期的迹象不谋而合，即沿着滑动方向排列的微震活动条纹是蠕动断层的共同特征。在靠近Loma Prieta主滑移带的地方，震源机制更加多样，遇到了断层弯曲。该地区的相对地震重新定位需要解决的科学问题包括寻找断层弯曲褶皱地震，区分异常震源机制的节面以确定实际的断裂面，以及总体上完善发生在主震周界以外的余震与发生在主震滑移区内或附近的余震之间的已知区别。这项研究是国家减少地震灾害计划的一部分。

9814994RubinThis research involves the extension of a precision earthquake relocation method to large numbers of events and to more diverse tectonic frameworks within volcanoes and active fault zones. Work has begun on events following the 1989 Loma Prieta, California, earthquake. Southeast of the main shock, along the transition to the creeping section of the San Andreas to the south, relocations comprising over 60% of the earthquake population show that much of the seismicity is concentrated in linear, nearly horizontal bands separated by regions that are presumably slipping largely aseismically. This coincides with earlier indications that streaks of microseismicity aligned in the slip direction are a common feature of creeping faults. Closer to the main Loma Prieta slip zone, focal mechanisms are more diverse and fault bends are encountered. Scientific issues to be addressed by the relative earthquake relocation in this region include searching for fault-bend folding earthquakes, discriminating between the nodal planes of the anomalous focal mechanisms to determine the actual fault planes, and generally refining what is known of the distinction between aftershocks that occur beyond the main shock perimeter and those that occur within or adjacent to the area of mainshock slip. This research is a component of the National Earthquake Hazard Reduction Program.