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计算了发生在亚平宁山脉(意大利)的几个地震所导致的静态应力变化。与断层滑动有关的静态应力运用Okada(1992)提供的公式计算。形成1980年伊尔皮尼亚M_S=6.9主震的3个子事件造成的静态应力变化表明,每个子事件都连续地被前面的子事件所触发。而且,这个复杂断层事件的余震与库仑应力增加的区域有很好的相关性。区域应力与主震产生的局部应力变化之间的相互作用导致了比预想的更宽些的余震分布,并且震源机制也有很大的变化。震源机制的变化与低水平的区域应力背景(小于2MPa)相符合。并且,伊尔皮尼亚地震产生的静态应力变化似乎在邻近的构造区(波坦察城附近)触发了一个中等震级(M_L≈5)的地震序列,只是延迟了几年。进一步发生在亚平宁山脉中部的两个地震,一个于1979年发生在诺尔恰城附近(M_L=5.9),一个于1984年发生在阿布鲁泽国家公园(M_L=5.5),余震和主震所产生的正库仑应力变化有清晰的相关关系。1979年诺尔恰地震的余震丛集在主断层的两个侧向边缘,这正是局部应力变化远低于区域应力场的中等震级的主震所期望的。1984年阿布鲁泽地震的主震产生的静态应力变化可能在4天后触发了主断层北边缘的又一个主震(M_L=5.1),在那里,库仑应力的变化最大。证据表明,亚平宁山脉的地震之间通过静态应力变化,在多个时间和空间尺度上有很强的相关性。这样的模拟结果对于改善我们对地震动力学的认识和更好地估计地震危险性是有用的。
The static stress changes caused by several earthquakes occurred in the Apennines (Italy) were calculated. The static stress associated with fault slip is calculated using the formula provided by Okada (1992). The static stress changes resulting from the three sub-events of the 1981 main MMI of M = 6.9 indicate that each sub-event is continually triggered by the preceding sub-event. Moreover, aftershocks for this complex fault event correlate well with areas of increased Coulomb stress. The interaction between regional stress and local stress changes caused by the mainshock leads to a wider aftershock distribution than expected, and the source mechanism also varies greatly. Changes in focal mechanism coincide with low-level regional stress backgrounds (less than 2 MPa). Moreover, the static stress changes induced by the Irpinia earthquake appear to trigger a seismic sequence of medium magnitude (M_L ≈ 5) in the adjacent tectonic zone (near Potenza), only a few years later. Two further earthquakes occurred in the middle of the Apennines, one occurring near Norcás in 1979 (M_L = 5.9) and one in Abruzzo National Park (M_L = 5.5) in 1984, resulting from aftershocks and mainshocks The positive Coulomb stress changes have a clear correlation. The aftershocks of the Norcross earthquake in 1979 converged on both lateral edges of the main fault, which is exactly what is expected of a mainshock of medium magnitude where the local stress changes far below the regional stress field. After 4 days, another major mainshock (M_L = 5.1) on the northern margin of the main fault may trigger a change in the static stress produced by the main shock of the Abruze earthquake in 1984, where the Coulomb stress changes most. Evidence shows that there is a strong correlation between earthquakes in the Apennines over a number of temporal and spatial scales through static stress changes. Such simulation results are useful for improving our understanding of seismic dynamics and for better estimating seismic hazards.