The 1992 Landers Earthquake: Effect of Crustal Heterogeneity on Earthquake Generation
The 1992 Landers Earthquake: Effect of Crustal Heterogeneity on Earthquake Generation
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DOI：
10.1002/cjg2.1149
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发表时间：
2007-09
期刊：
影响因子：
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通讯作者：
You Tian;Dapeng Zhao;Rou‐Mei Sun;J. Teng
中科院分区：
文献类型：
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作者：
You Tian;Dapeng Zhao;Rou‐Mei Sun;J. Teng
为了了解地震发生与地壳非均质性之间的关系，我们利用南加州永久和临时台站记录的1992年兰德斯余震和其他当地地震的107401个纵波和19624个横波高质量到达时间，确定了兰德斯地震区下方详细的三维纵横波速度和泊松比结构。我们的结果显示了地震破裂带和地壳不均匀性之间的相关性。兰德斯余震呈簇状分布，并在存在低速异常的地区分离或终止。 4级以上的大地震大多发生在纵波速度较高的地区及其周围。可能性是，高速区域可能是脆弱而坚固的部分，可以承受地震应力，因此可以产生地震。相反，低速区域可能具有较高的断裂程度、较高的流体压力或较高的温度，其中变形更有可能是抗震的。另外，根据纵波、横波速度分布以及泊松比，我们推断兰德斯地震区存在流体。流体的存在可能会削弱周围的地壳岩石，从而引发强烈地震。
In order to understand the relationship between earthquake occurrence and crustal heterogeneities, we used 107401 P- and 19624 S-wave high-quality arrival times from the 1992 Landers aftershocks and other local earthquakes which were recorded by both permanent and temporary stations in Southern California to determine detailed three-dimensional P- and S-wave velocity and Poisson's ratio structures beneath the Landers earthquake area. Our results show a correlation between the seismic rupture zones and crustal heterogeneities. The distribution of the Landers aftershocks is cluster-like and separated or terminated in the area where lowvelocity anomalies exist. Most of the large earthquakes with magnitudes bigger than 4 occur in or around areas with high P-wave velocity. The possibility is that high-velocity areas are probably brittle and strong parts which can sustain seismogenic stress, and so can generate earthquakes. In contrast, low-velocity areas may have either higher degree of fracture, high fluid pressure, or higher temperatures where deformation is more likely to be aseismic. In addition, we infer that fluids exist in the Landers earthquake area from the distribution of P- and S-wave velocity and Poisson's ratio. The existence of fluids may weaken the surrounding crustal rocks, then trigger strong earthquakes.