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世界上有些火山地震位于人口密集区,因此与喷发前地震活动有关的地震危险性及其对工程结构的潜在破坏应该是危险性评估及管理的一部分。维苏威火山(意大利南部)就是如此,在那里数十万人面临火山及相关的地震危险的威胁。通过对维苏威火山地震活动相应的震级、震中及震源机制进行地震波形的大量模拟,本文研究了喷发前地震活动的影响。进行地震合成处理,以求得强地面运动特征参数,这有利于估计建筑物多的地区由期望的最大单个地震事件和大量小地震的累积效应所造成的地震破坏。选择一组所记录的地震比较合成的和观测的强地面运动参数,以证实模拟方法是否可靠。由于在维苏威地区下面的浅深度存在明显的速度不连续性,不同距离的峰值地面加速度(PGA)似乎受地震深度的影响。另一方面,滞后能量谱与结构物的塑性变化有关,它明显取决于古登堡—里克特定律(G-R)的b参数。1997年在意大利翁布里亚—马尔凯发生的地震(M5·8),虽然并未记录到很大的峰值地面加速度值,但却造成了建筑物和基础设施的严重破坏,通过在合理的期望范围内改变G-R定律参数,我们注意到累积滞后能量与在翁布里亚—马尔凯震源附近的观测值是相当的。
Some of the world’s volcanic earthquakes are located in densely populated areas, so the seismic risk associated with pre-eruption seismic activity and its potential damage to engineering structures should be part of risk assessment and management. This is the case with Mount Vesuvius (southern Italy), where hundreds of thousands face the threat of volcanoes and associated seismic hazards. Through the massive simulation of the seismic waveforms of the magnitudes, epicenters and focal mechanisms of the Vesuvius volcanic activity, this paper studies the influence of the seismic activity before the eruption. Synthetic seismic processing to obtain strong ground motion parameters helps to estimate the seismic damage caused by the cumulative effects of the largest single expected seismic event and a large number of small earthquakes in many areas of the building. A set of well-documented and observed strong ground motion parameters are selected to confirm that the simulation method is reliable. Due to the apparent velocity discontinuity at the shallow depth below the Vesuvius area, peak ground acceleration (PGA) at different distances appears to be affected by the depth of the earthquake. On the other hand, the hysteresis energy spectrum is related to the plastic change of the structure, which obviously depends on the b parameter of Gutenberg-Rickett’s law (G-R). The earthquake that struck Umbria-Marche, Italy, in 1997 (M5.8), although it did not record a large peak ground acceleration value, resulted in serious damage to buildings and infrastructure, Changing the GR-law parameters as expected, we note that the cumulative hysteresis energy is comparable to observations near the Umbria-Marchelx source.