论文部分内容阅读
圣安德烈斯断层(美国加州)南段最后一次大地震距今已有153年了,而其平均震间间隔却仅为~100年。如果大地震的复发具有周期性,而并非随机发生或群集发生,则这个时间长度是很值得关注的,而且通常意味着概率意义上的地震危险性增大。遗憾的是,多数地震记录都很简单,这就限制了对单条断层上地震复发的分布特征的描述。本文利用加州Wrightwood 3000年中29次有地面破裂的地震的综合记录进行统计检验。结果表明此处地震的复发远比依据泊松分布预测的结果更具规律性,而且也不呈群集分布,由此,我们推断地震的复发具有准周期性。基于观测的敏感性分析对可供选择的地质记录解释进行严格检验,结果揭示出持续的单峰时间依从特征。这一结果为利用更新模型来正式预测圣安德烈斯断层南段未来地震概率提供了有力的支持。根据记录,仅有4个间隔(15%)长于目前的开放间隔,由此凸显了该断层当前地震形势的严峻性。
The last earthquake in the southern section of the San Andres Fault (California, USA) has been around for 153 years, while its average interval between earthquakes is only ~ 100 years. This length of time is noteworthy if the recurrence of large earthquakes is periodic, not random or clustered, and usually means that the probabilistic seismic hazard increases. Unfortunately, most seismic records are simple, which limits the description of the distribution of seismic recurrences on a single fault. In this paper, a statistical test was performed using a comprehensive record of 29 ground-ruptured earthquakes in Wrightwood, California in 3000. The results show that the recurrence of earthquakes here is far more regular than that predicted by Poisson distribution, and no cluster distribution is found. Therefore, we infer that the earthquake recurrence is quasi-periodic. A rigorous test of alternative geological record interpretation based on observed sensitivity analyzes revealed a consistent monolayer time-dependent character. This result provides strong support for using the updated model to formally predict the future earthquake probabilities in the southern section of the San Andreas Fault. According to the records, only 4 intervals (15%) are longer than the current open interval, thus highlighting the seriousness of the current seismic situation of the fault.