Massive Microearthquake Relocation: Technique Development and Application to Seismotectonics

9814994Rubin这项研究涉及到将精确地震重定位方法扩展到大量事件以及火山和活动断层带内更多样化的构造框架。 1989年加州洛马普列塔地震后的事件工作已经开始。 主震的东南部，沿着向南的圣安德烈亚斯蠕动段的过渡，包括超过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，几乎水平的带分离的区域，大概是滑动主要抗震。 这与早期的迹象相吻合，即沿滑动方向排列的微震活动条纹是蠕动断层的共同特征。 靠近主洛马普列塔滑动带，震源机制更加多样化，遇到了断层弯曲。 在这一地区，相对地震重新定位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层面，以及一般地细化已知的发生在主震周边以外的余震与发生在主震滑动区域内或附近的余震之间的区别。这项研究是国家地震减灾计划的一个组成部分。

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.