Development for Statistical Earthquake forecasting. Seismic and geodetic anomalies preceding the rupture around the focal region detected by statistical models

地震平静和地震活动作为大地震的前兆，引起了地震学家的广泛关注。特别令人感兴趣的假设是，从一个地区的破裂或无声滑移转移的应力变化可以在其他地区引起地震变化。然而，由于连续地震是在非均质分形介质下由复杂的机制触发的，地震的丛集性使我们无法探测到由其他区域的应力变化引起的地震活动变化。然而，我们可以利用统计经验法则作为预测震群的一种实用方法。因此，本研究的目的是证明，基于传染病类型余震序列(ETAS)模型与区域地震活动拟合的诊断分析有助于检测该地区的外源应力变化。特别是，由于无声滑移引起的变化通常是如此轻微，以至于人们几乎认不出系统性的Anoma…没有ETAS模型的帮助，更多的在于地震的活动性。利用ETAS的地震触发模型可以很好地预测一个地区的普通短期地震发现率。任何异常的地震活动，如静止和激活，都可以通过识别与预测速率的显著偏差来量化。因此，我们已经成功地进行了一些案例研究。例如，这种异常被发现发生在2004年日本中部中津6.8级地震之前的三年时间里。发生在库仑破裂应力负值和正值增量区域的静止和激活，可能是由于震源断裂面上的无声滑移或其较深的低倾角伸展引起的，这种滑移进一步得到了围绕破裂源区的瞬时地壳运动的支持。多个永久GPS站之间基线距离的时间序列记录与预测的线性趋势有明显的偏离，这些偏差大多与楚楚地震引起的GPS站的同震水平位移一致。此外，主震断层面伸展越深，倾角越小，可以解释与理论位移相比，观测到的基线偏差更多的情况。累积的前兆滑动估计在矩震级上大致相当于M6。较少

Seismic quiescence and activation, as the precursors to large earthquakes, have attracted much attention among seismologists. Of particular interest is the hypothesis that the stress-changes transferred from a rupture or silent slip in one region can cause seismic changes in other regions. However, the clustering feature of earthquakes prevents us from detecting the seismicity change due to stress change transferred from other region because successive earthquakes are triggered by complex mechanisms under heterogeneous fractal media. Nevertheless, we can use the statistical empirical laws as a practical method for predicting earthquake clusters. Thus, the objective of this research is to demonstrate that diagnostic analysis based on fitting the Epidemic Type Aftershock Sequence (ETAS) model to regional seismicity can be helpful in detecting exogenous stress changes there. In particular, the changes due to silent slips are usually so slight that one can barely recognize systematic anoma … More lies in seismicity without the aid of the ETAS model.The ordinary short-term occurrence rate of earthquakes in a region is well predicted using the ETAS model of triggering earthquakes. Any anomalous seismic activity, such as quiescence and activation, can be quantified by identifying significant deviation from the predicted rate. Thus we have successfully made a number of case studies. For example, such anomalies are revealed to have occurred during the three year period leading up to the 2004 Chuetsu Earthquake of Magnitude 6.8, central Japan. The quiescence and activation, which took place in the region of negative and positive increments of the Coulomb Failure Stress, respectively, were possibly caused by silent slip on the focal fault plane, or its deeper extension with a lower dip angle.Such slip is further supported by transient crustal movement around the rupture source. The time series records of many baseline distances between the permanent GPS stations significantly deviated from the predicted linear trends, mostly with the deviations consistent with the coseismic horizontal displacements of the GPS stations due to the Chuetsu Earthquake. Furthermore, a deeper extension of the mainshock fault plane, with a lower dip angle, can explain the more cases of the observed baseline deviations in comparison with the theoretical displacement. The cumulated precursory slip is estimated to be roughly equivalent to M6in the moment magnitude. Less