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应力扰动影响地震的复发,并对了解地震周期和地震危险性具有重要的作用。加州帕克菲尔德圣安德烈斯断层上的大量重复地震为检查重复事件对中强地震发生的反应提供了难得的机会。使用高分辨率地震台网目录获得的187个M-0.4～1.7级地震重复序列,我们发现重复事件序列的复发时间到接近M4-5地震时缩短了,说明是由大地震触发的。该触发效应在5km左右的距离内最明显,相应的静态同震应力变化为0.6～26.6kPa,并随距离衰减。我们还发现从1993至1998年复发间隔相应地缩短了。这种几年经久不衰复发加速反映了1990年代初断层滑动加速并提高了加载速率。
Stress disturbances affect the recurrence of earthquakes and play an important role in understanding the seismic cycles and seismic hazards. The large number of repeated earthquakes on the San Andreas Fault in Parkfield, California provide a unique opportunity to examine the response of repetitive events to moderately strong earthquakes. Using 187 M-0.4 to 1.7 earthquake repetitions obtained from the catalog of high-resolution seismological stations, we found that the recurrence time of the repetitive events was shortened to near the M4-5 earthquake, indicating that it was triggered by a large earthquake. The triggering effect is most obvious within a distance of about 5km. The corresponding static coseismic stress changes from 0.6 to 26.6 kPa and decays with distance. We also found that the relapse interval was correspondingly shortened from 1993 to 1998. The accelerated years of prolonged recurrences reflect fault slip accelerations and increased loading rates in the early 1990s.