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对由大地震引起的静应力变化的计算结果说明,余震的空间分布是能够在一级精度上做出预测的,因为余震首先发生在正的应力变化地区。这些地区的划分需要将应力扰动分解到已知取向的平面上;通常的做法是用了解不多的区域应力信息来计算最佳取向的破裂面,并假设这些面无处不在。本文我们说明这种假设未得到观测的支持,而是余震破裂面受地质构造的控制。我们坚持认为,用构造取向的统计量度代替区域应力信息做出的余震危险性评估更有价值。
The calculation of the static stress caused by a large earthquake shows that the spatial distribution of aftershocks can be predicted with first-order accuracy because aftershocks first occur in areas of positive stress change. The division of these areas requires that stress perturbations be resolved into planes of known orientation; it is common practice to calculate well-oriented rupture planes with poorly understood regional stress information and assume that the surfaces are ubiquitous. In this paper we show that this assumption is not supported by observations but that the rupture surface of aftershocks is controlled by the geological structure. We insist that valuing the aftershock hazard assessment using structural-based statistical measures instead of regional stress information is more valuable.