Space-time model for repeating earthquakes and analysis of recurrence intervals on the San Andreas Fault near Parkfield
Space-time model for repeating earthquakes and analysis of recurrence intervals on the San Andreas Fault near Parkfield
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帕克菲尔德附近圣安德烈亚斯断层重复地震时空模型及复发间隔分析
DOI：
10.1002/2013jb010558
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发表时间：
2014
影响因子：
--
通讯作者：
R.M.
中科院分区：
文献类型：
--
作者：
Nomura;S.;Ogata;Y. and Nadeau;R.M.
我们提出了一个随机模型的特点重复地震序列估计的时空变化的静态应力加载速率。这些地震通过循环机制重复发生，其中震源处的应力通过构造力积累，直到地震发生，将积累的应力释放到基准水平。更新过程经常被用来描述这种重复的地震机制。然而，由于大地震和无源滑动瞬变引起的构造载荷速率的变化将非平稳效应引入重复机制，导致事件间隔时间的非平稳趋势，特别是对于具有较短事件间隔时间的较小震级重复事件。这些趋势在具有相似震源的重复地震地点之间也是相似的。因此，我们将三次B-样条函数表示的时空结构纳入更新模型，并在贝叶斯框架下通过最大化集成似然来估计其系数参数。我们将我们的模型应用到31个重复的地震序列，包括824个事件的Parkfield段的圣安德烈亚斯断层和估计的时空过渡的加载速率在这一段。结果为我们提供了由1993年的一次地震滑动瞬变、2004年帕克菲尔德6级地震以及其他附近或远程地震活动引起的构造载荷变化的详细信息。重复事件复发间隔的周期性程度也显示了空间趋势，即使在2004年帕克菲尔德地震后，时间尺度相对于估计的加载速率进行归一化时，这些趋势也在时间上保持不变。
We propose a stochastic model for characteristically repeating earthquake sequences to estimate the spatiotemporal change in static stress loading rate. These earthquakes recur by a cyclic mechanism where stress at a hypocenter is accumulated by tectonic forces until an earthquake occurs that releases the accumulated stress to a basal level. Renewal processes are frequently used to describe this repeating earthquake mechanism. Variations in the rate of tectonic loading due to large earthquakes and aseismic slip transients, however, introduce nonstationary effects into the repeating mechanism that result in nonstationary trends in interevent times, particularly for smaller‐magnitude repeating events which have shorter interevent times. These trends are also similar among repeating earthquake sites having similar hypocenters. Therefore, we incorporate space‐time structure represented by cubic B‐spline functions into the renewal model and estimate their coefficient parameters by maximizing the integrated likelihood in a Bayesian framework. We apply our model to 31 repeating earthquake sequences including 824 events on the Parkfield segment of the San Andreas Fault and estimate the spatiotemporal transition of the loading rate on this segment. The result gives us details of the change in tectonic loading caused by an aseismic slip transient in 1993, the 2004 ParkfieldM6 earthquake, and other nearby or remote seismic activities. The degree of periodicity of repeating event recurrence intervals also shows spatial trends that are preserved in time even after the 2004 Parkfield earthquake when time scales are normalized with respect to the estimated loading rate.