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破裂扩展方向是影响地震引发地震动方式的重要因素。因此,表征促进潜在破裂扩展方向的因素是极其重要的。本文分析了加州帕克菲尔德附近圣安德烈斯断层上反复发生的地震序列的地震方向性。同一序列中的所有地震都有非常相似的波形并有重叠的地表破裂。我们说明,普通序列地震之间传递函数的微妙变化可以被认为是视破裂持续时间的改变。计算了所有可用台站的成对地震事件以及每个序列的相对视破裂持续时间。我们反演这些测量结果,得到了序列中各单一事件相对于参考事件的视破裂持续时间的估计值。视破裂持续时间随方位的变化证实了破裂方向性。我们说明,大多数所分析的微震显示为东南向破裂。我们还说明,在给定的重复序列中,大多数地震往往显示出相同的破裂方向。
The direction of rupture expansion is an important factor that affects the earthquake induced mode of earthquake. Therefore, it is extremely important to characterize the factors that promote the direction of potential rupture expansion. This paper analyzes the seismicity of recurrent earthquake sequences on the San Andres Fault near Parkfield, California. All earthquakes in the same sequence have very similar waveforms and have overlapping surface ruptures. We show that the subtle change of the transfer function between ordinary series of earthquakes can be considered as the change of duration of rupture. Paired seismic events for all available stations and the relative apparent fracture duration of each sequence were calculated. We inverted these measurements and obtained estimates of the duration of apparent rupture of each single event in the series relative to the reference event. The duration of rupture as a function of orientation confirms the rupture direction. We show that most of the microseisms analyzed show a southeast crack. We also show that most earthquakes often show the same direction of rupture in a given repeat sequence.