[S-SS10] 地震活動とその物理

[SSS10-12] Global background earthquakes have shown a steady trend over the past twenty years

*熊 子瑶¹、庄 建倉¹ (1.統計数理研究所)

Whether large earthquakes have triggering effects on other regions of the globe has been a matter of interest, and studies on global triggering of large earthquakes have proliferated. However, most studies only focus on a single event or a local area, and it is difficult to reflect the global interaction between earthquakes. This study is based on the SETAS (spherical ETAS) model to fit the global seismic events, thus responding to the interrelationship between seismic events from the perspective of the occurrence of earthquake sequences. SETAS model is modified from the widely used planar space-time ETAS model, which is applicable to analyze and forecast seismicity in high latitude regions or on a global scale.
We studied the relationship between global major earthquakes and seismic activity in the global scale. And analyzed the relationship between time and cumulative frequency of total earthquakes, background earthquakes and clusters. The results show that the global background earthquakes have stabilized in the past twenty years. And clusters are about 1/3 of the global earthquakes with magnitude 5.15 or above.