Comprehensive study for statistical prediction of seismic activity

这项研究的一个重要成果是使用统计模型作为诊断工具来识别地震活动模式的异常趋势和其他特征。 ETAS 模型本身是检测地震活动异常特征（包括余震活动）以及识别和定义地震静止状态的极其有用的工具。将实际地震活动速率与 ETAS 模型预测的速率进行比较的结果对于控制地震活动演化过程的物理解释具有非常有趣的意义。最近的几篇重要出版物强调并讨论了地震活动率变化和同震应力变化之间的联系。特别值得注意的是，与 ETAS 模型相关的相对静止定义代表了当前可用的“应力阴影”的最佳定义和物理解释。换句话说，这代表了应力阴影最稳健的定义，并且所提出的数值方法是识别地震活动率降低的最佳解决方案。这已经得到了科学界的认可。我们提出了分层时空ETAS模型，该模型被扩展用于地震目录时空坐标的应用。区域地震发生率被建模为先前活动的函数，其具体形式基于经验法则，例如修正的大森公式和余震面积与震级的 Utsu-Seki 标度法则。其参数（包括余震衰减率的 p 值）可能因地点而异。该模型用于可视化日本及其周边地区的区域地震活动特征。在模型的五个参数中，K参数（余震生产力）的空间变化可以与粗糙体位置很好地相关。此外，该模型使我们能够增强实际发生率与模型发生率系统性偏差的区域。特别是第二类相对静止或地震间隙备受关注。此外，我们研究的附带结果包括时空 ETAS 模型的随机聚类/去聚类过程，这使得另一种诊断工具能够在给定数据集时检查时空模型的充分性。较少的

One important outcome emerging from this study is the use of statistical models as diagnostic tools to identify anomalous trends and other features of the seismicity pattern. The ETAS model itself is an extremely useful tool in detecting anomalous features in seismic activity, including aftershock activity, and in identifying and defining seismic quiescence. The results of comparing the actual seismicity rates with the rates predicted by the ETAS model have very interesting implications for the physical interpretation of the processes controlling the evolution of seismicity. The connections between seismicity rate changes and coseismic stress changes have been emphasized and discussed in several important recent publications. In particular, it is worth noting that the relative quiescence defined in relation to the ETAS model represents the best currently available definition and physical interpretation of the "stress shadow". In other words, this represents the most robust definition t … More he stress shadow and the proposed numerical approach is the best solution to identify seismicity rate reductions. This has been recognized by the scientific community.We have proposed the Hierarchical Space-Time ETAS model that is extended for applying space-time coordinates of earthquake catalogs. Regional earthquake occurrence rate is modeled as a function of previous activity whose specific form is based on empirical laws such as the modified Omori formula and the Utsu-Seki scaling law of aftershock area against magnitude. Its parameters, including the p-value of the aftershock decay rate, can vary from place to place. This model is used to visualize features of the regional seismic activities in and around Japan. Among the five parameters of the model, the spatial variation of the K-parameter (the productivity of aftershocks) can be well correlated with asperity locations. Furthermore, the model enables us to enhance the regions where the actual occurrence rates deviate systematically from the modeled one. In particular, the relative quiescence or the seismic gap of the second type is of great concern. Also, the incidental outcomes of our research include the stochastc clustering / declustering procedure by the space-time ETAS model, which enables another diagnostic tool to examine the adequacy of a space-time model when we are given a dataset. Less