Strongly Depth-Dependent Aftershock Production in Deep Earthquakes
Strongly Depth-Dependent Aftershock Production in Deep Earthquakes
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DOI：
10.1785/012003191
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发表时间：
2004-10
影响因子：
3
通讯作者：
S. Persh;H. Houston
中科院分区：
文献类型：
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作者：
S. Persh;H. Houston
在100公里深度以下的高压下发生地震破裂的机制仍然是个谜，也是有争议的。深源地震和浅源地震之间最明显的区别是100公里以下的余震很少。我们报告强烈的变化，余震生产力与深度。在100 ~ 300 km范围内，考虑主震震级影响的余震产率比浅源地震产率低一个数量级以上。在300至550公里之间，余震发生率特别低，约为100至300公里之间水平的三分之一。然而，在550公里以下，余震发生率突然增加到100至300公里之间的两倍多。类似的模式也出现在余震生产力的替代措施中，包括余震的原始数量，有余震的主震的比例，以及余震释放的主震地震矩的比例。余震生产力的深度依赖性与先前提出的300公里深度附近地震发生机制的变化是一致的。值得注意的是，550 km以下余震产率的突然增加与地震持续时间和复杂性的突然减少相对应，并表明该深度的破裂机制也发生了重大变化。在线资料：本研究中使用的主震和相关余震目录。
The mechanisms that permit earthquake rupture at the high pressures occurring below 100 km depth remain enigmatic and controversial. The most distinct difference between deep and shallow earthquakes is a scarcity of aftershocks below 100 km. We report strong changes in aftershock productivity with depth. From 100 to 300 km, aftershock productivity normalized to account for the effect of main- shock magnitude is more than an order of magnitude lower than that of shallow events. Between 300 and 550 km, aftershock productivity is particularly low, falling to about one-third the level between 100 and 300 km. Below 550 km, however, aftershock productivity abruptly increases to more than twice as great as that between 100 and 300 km. A similar pattern is seen in alternate measures of aftershock productivity, including the raw numbers of aftershocks, the fraction of mainshocks that have aftershocks, and the fraction of mainshock seismic moment released in aftershocks. The depth dependence of aftershock productivity is consistent with a previously proposed change in earthquake generation mechanism near 300 km depth. Notably, the abrupt increase in aftershock productivity below 550 km corresponds with abrupt decreases in earthquake duration and complexity and sug- gests a major change in the rupture mechanism at that depth, as well. Online Material: Catalog of mainshocks and related aftershocks used in this study.