Stress-forecasting (not predicting) earthquakes: A paradigm shift?
Stress-forecasting (not predicting) earthquakes: A paradigm shift?
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DOI：
10.1130/g24643a.1
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发表时间：
2008-05-01
期刊：
影响因子：
5.8
通讯作者：
Peacock, Sheila
中科院分区：
文献类型：
--
作者：
Crampin, Stuart;Gao, Yuan;Peacock, Sheila
经过120年的不成功的奋进，在地震可以预测之前，需要一个范式转变。最敏感的诊断低水平的应力变化在原地岩石，微裂纹的几何形状的变化，可以监测通过分析剪切波分裂。建议的范式转变是，而不是调查震源区，我们监测地震前的应力积累，可能的话，从源相当大的距离。在回顾世界范围内14次地震前，观察到剪切波时间延迟的特征时间变化。有一次，当足够早地认识到变化时，冰岛西南部M = 5地震的时间、震级和断层破裂在狭窄的时间-震级窗口内成功地进行了应力预测。这种应力积累可以在理论上建模，并且被认为至少部分地被理解。当足够的剪切波源地震是可用的，增加的时间延迟也显示出一个突然减少前不久即将发生的地震。这还没有完全理解，但被认为是由应力松弛引起的，因为微裂纹合并到最终的断层破裂上。新的结果证实了这些想法，并证明了范式的转变，即时间延迟的增加和减少的持续时间的平方和被发现与即将发生的地震的震级成比例（自相似）。
After 120 years of unsuccessful endeavor, a paradigm shift is required before earthquakes can be predicted. The most sensitive diagnostic of low-level changes of stress in in situ rock, variations in microcrack geometry, can be monitored by analyzing shear-wave splitting. The suggested paradigm shift is that, instead of investigating the source zone, we monitor stress accumulation before earthquakes at, possibly, substantial distances from the source. Characteristic temporal variations of shear-wave time delays have been observed in retrospect before 14 earthquakes worldwide. On one occasion, when changes were recognized early enough, the time, magnitude, and fault break of an M = 5 earthquake in southwest Iceland were successfully stress-forecast in a narrow time-magnitude window. Such stress accumulation can be theoretically modeled and is believed to be at least partially understood. When sufficient shear-wave source earthquakes are available, increasing time delays also show an abrupt decrease shortly before the impending earthquake occurs. This is not fully understood but is thought to be caused by stress relaxation as microcracks coalesce onto the eventual fault break. The new result confirming these ideas, and justifying the paradigm shift, is that logarithms of the durations of both increases and decreases in time delays are found to be proportional (self-similar) to the magnitudes of impending earthquakes.