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地震通常在时空上是丛集的。传统的地震危险性分析所考虑的只是每个地震丛集中最大震级的事件——主震,并用所考虑场地地震动强度量值的超越率来表示(Cornell,1968)。这种地震危险性概率分析(PSHA)用于长期的结构设计或评估。近来,出于对短期风险的管理,已采用一种类似的方法来进行余震地震危险性概率分析(APSHA),其与主震的发生相关(Yeo and Cornell,2009)。地震危险性概率分析通常用一种均匀泊松过程来描述事件的发生,而余震地震危险性概率分析则通过有条件的非均匀泊松过程来模拟余震的发生,其概率值取决于触发余震序列的主震震级。另外,由主震和后续余震组成的每个地震丛集,可以看成以相同主震概率发生的单一事件。这就可以用相对简单的方式在危险性分析中考虑余震,这个方法首先由Toro和Silva(2001)论证,并由Boyd(2012)进一步研究。实际上,这篇短文中心探讨概率方面,说明地震危险性概率分析和余震地震危险性概率分析的联合结果以得到一种考虑主震—余震序列的地震危险性整体解析解的可行性,而前面提到的研究中这些仍然缺乏。这种方法应用的结果,说明有助于依据导致超越某一加速度阈值同时也考虑余震的地震事件发生率(如对于结构设计),初步评估地震危险性的增加。因而这从地震工程长远来看是切合实际的方向。
Earthquakes are often clustered in space and time. The traditional seismic risk analysis considered only the event of the largest magnitude in each earthquake cluster, the mainshock, and represented the overrun of the magnitude of the seismic intensity of the site under consideration (Cornell, 1968). This seismic hazard probability analysis (PSHA) is used for long-term structural design or evaluation. Recently, a similar approach has been adopted for the management of short-term risks for aftershock seismic hazard probability analysis (APSHA), which correlates with the occurrence of mainshock (Yeo and Cornell, 2009). The probability analysis of earthquake risk usually describes the occurrence of an event by an even Poisson process, while aftershock seismic hazard probability analysis simulates the occurrence of aftershocks through conditional non-uniform Poisson process. The probability value depends on the triggered aftershock sequence The main shock magnitude. In addition, each earthquake cluster consisting of a main shock and subsequent aftershocks can be viewed as a single event with the same probability of a main shock. This makes it possible to consider aftershocks in a hazard analysis in a relatively easy way, first demonstrated by Toro and Silva (2001) and further studied by Boyd (2012). In fact, this essay discusses probabilistic aspects of the joint results of a probabilistic analysis of seismic hazard probability and aftershock seismic hazard probabilities to arrive at a viable global solution to a seismic hazard considering mainshock-aftershock sequences, whereas the previous These are still missing in the mentioned studies. The results of the application of this method demonstrate the preliminary assessment of the increased seismic hazard based on the occurrence of seismic events (such as for structural design) that lead to surpassing of an acceleration threshold and aftershock. Therefore, this is a realistic direction from the seismic engineering in the long run.