Modifications of epidemic-type-aftershock-sequence models for characterizing diffusive shear slips of deep long-period earthquakes
Modifications of epidemic-type-aftershock-sequence models for characterizing diffusive shear slips of deep long-period earthquakes
复制标题
描述深部长周期地震扩散剪切滑移的流行型余震序列模型的修正
DOI：
10.1093/gji/ggad125
复制
发表时间：
2023
影响因子：
2.8
通讯作者：
Terai Nozomi
中科院分区：
文献类型：
--
作者：
Aso Naofumi;Terai Nozomi
深长周期地震(DLP)是地壳下部的主要地震事件，可以提供有关地球演化的重要信息。为了捕捉任何与流体有关的扩散现象，我们试图通过修改流行病类型余震序列(ETAS)模型来将DLP的群状性质转换为扩散性质，ETAS模型是评估地震活动的标准工具。修正后的ETAS模型成功地解释了日本岛根东部DLP的地震活动。扩散迁移率可能没有普通地震的破裂速度那么高，但仍然足以将缓慢的形变与低频地震辐射联系起来。DLP的主要力学过程可能是剪切滑移，因为观测到的扩散系数(10~3-10~5m~2/S)远大于浅层火山事件的估计值(100~101m~2/S)，但与构造地震(10~4-105m~2/S)相近。虽然板块界面上的无地震滑动的面积范围比火山根部不太成熟的系统中的大，但构造低频地震往往比火山DLP小。地震斑块通过普遍的扩散剪切滑移引起地震的概念可以独立地解释这一悖论。
Deep long-period earthquakes (DLPs) are the major seismic events in the lower crust and can provide important information on the evolution of the Earth. To capture any fluid-related diffusive phenomena, we attempted to translate the swarm-like nature of DLPs into a diffusive one by modifying the epidemic-type aftershock sequence (ETAS) model, which is a standard tool for evaluating seismicity. The modified ETAS model explained the seismicity of DLPs in eastern Shimane, Japan successfully. The diffusional migration rate may not be as high as the rupture velocity of ordinary earthquakes, but it is still sufficient to associate slow deformation with low-frequency seismic radiation. The principal mechanical process of DLPs is likely shear slip, since the observed diffusivity (103–105m2/s) is much larger than estimates for shallow volcanic events (100–101m2/s), but close to those of tectonic tremors (104–105m2/s). While the areal extent of aseismic slips is greater on the plate interface than in a less-mature system at volcanic roots, tectonic low-frequency earthquakes tend to be smaller than volcanic DLPs. The concept that seismic patches cause these earthquakes via universal diffusive shear slips can independently explain this paradox.