Coherent tilt signals observed in the Shumagin Seismic Gap: Detection of time‐dependent subduction at depth?
Coherent tilt signals observed in the Shumagin Seismic Gap: Detection of time‐dependent subduction at depth?
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在舒马金地震间隙观察到的相干倾斜信号：检测深度随时间变化的俯冲？
DOI：
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发表时间：
1984
期刊：
影响因子：
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通讯作者：
K. Hurst
中科院分区：
文献类型：
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作者：
J. Beavan;R. Bilham;K. Hurst
对阿拉斯加舒马金群岛短水平线的反复测量，揭示了与舒马金地震间隙中北美板块下太平洋板块俯冲有关的连贯倾斜信号。十年来向海沟的稳定倾斜在1978-1980年间被一次快速的反向倾斜打断。正常倾斜表示当板块边界锁定在至少60公里深度时发生俯冲时的地表变形。利用所有可用的倾斜、海平面和地震数据，作者将倾斜逆转解释为在大约70公里至20公里深度之间的板块边界上发生了大约80厘米级的间歇性逆滑，从主孕震带向下倾斜，仍然处于锁定状态。这一事件导致锁定的主逆冲带的应力增加。作者推测，这样的事件可能是俯冲带的一个常规过程，大板块边界地震在发生时可能更常见，而且它们的发生可能足够早地被探测到，从而对大地震发生的可能性增加发出警告。参考文献51篇，图10张，表1张。
Repeated surveys of short level lines in the Shumagin Islands, Alaska, reveal coherent tilt signals associated with subduction of the Pacific plate beneath the North American plate in the Shumagin seismic gap. Ten years of steady tilt down toward the trench is interrupted during 1978-1980 by a rapid episode of reverse tilt. The normal tilt represents surface deformation as subduction occurs with the plate boundary locked to at least 60 km depth. Using all available tilt, sea level, and seismic data, the authors interpret the tilt reversal as due to an episodic reverse slip of ca 80 cm magnitude on the plate boundary between ca 70 km and ca 20 km depth, downdip from the main seismogenic zone, which remains locked. This event causes an increase of stress on the locked main thrust zone. The authors speculate that such events may be a regular process at subduction zones, that great plate boundary earthquakes may be more common during their occurrence, and that their onset may be detectable early enough to give warning of an increase in probability for the occurrence of a great earthquake. 51 references, 10 figures, 1 table.