Interaction Between Aseismic Slip and Fluid Invasion in Earthquake Swarms Revealed by Dense Geodetic and Seismic Observations
Interaction Between Aseismic Slip and Fluid Invasion in Earthquake Swarms Revealed by Dense Geodetic and Seismic Observations
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密集大地测量和地震观测揭示地震群中抗震滑移与流体侵入的相互作用
DOI：
10.1029/2021jb022933
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Honda R.
中科院分区：
文献类型：
--
作者：
Yukutake Y.;Yoshida K.;Honda R.
最近的地震和大地测量观测表明，在震群期间，加压流体和地震滑动的参与。然而，这两个因素之间的相互作用并没有得到充分的理解。在这项研究中，我们表现出大地测量信号引起的地震断层上的开口和剪切位错，伴随着震源迁移在箱根火山，日本中部的地震群。震源集中在一个垂直平面上，震源机制是走滑断层，其节面与震源分布一致。前兆地震活动发生在主震群前1周。我们观察到一个复杂的模式，震源迁移过程中的地震序列，即，地震活动的下限似乎向下扩展，在间接地震活动，其次是一个向上的震源扩散。我们还观察到倾斜的变化，可以解释从平面震源分布推断断层面上的开放和剪切位错。此外，我们还发现了几组重复发生的地震。从重复地震中推断的平均地震滑动历史表明，在重复地震活动期间，地震滑动为0.4 mm，在主震群期间，地震滑动加速至3 mm。总的累积滑动量与大地模型结果一致。这些观测结果可能表明，流体的侵入导致了地震滑动，而震源的复杂迁移反映了地震滑动的传播。我们假设，无源形变与加压流体的侵入共同起着震群的驱动力作用。
Recent seismic and geodetic observations suggest the involvement of pressurized fluid and aseismic slip during earthquake swarms. However, the interaction between these two factors is not fully understood. In this study, we show geodetic signals induced by aseismic opening and shear dislocation on a fault, accompanied by hypocenter migration during an earthquake swarm in the Hakone volcano, central Japan. The hypocenters were concentrated on a vertical plane, and the focal mechanisms were strike‐slip faults whose nodal planes were consistent with the hypocenter distribution. Precursory seismicity occurred 1 week before the main swarm. We observed a complex pattern of hypocenter migration during the seismic sequence; namely, the lower limit of the seismicity appears to expand downward during the precursory seismicity, followed by an upward hypocenter diffusion. We also observed tilt changes that could be explained by opening and shear dislocation on the fault plane inferred from the planar hypocenter distribution. Furthermore, we identified several groups of repeating earthquakes. The average aseismic slip history inferred from the repeating earthquakes indicated a minor aseismic slip of 0.4 mm during the precursory seismic activity, which accelerated by up to 3 mm during the main swarm. The total cumulative slip was consistent with the geodetic model results. These observations may suggest that fluid intrusion caused the aseismic slip, and the complex migration of the hypocenters reflects the aseismic slip propagation. We hypothesize that aseismic deformation acts as the driving force for the earthquake swarms together with the intrusion of pressurized fluid.
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DOI：
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发表时间：
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期刊：
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影响因子：
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发表时间：
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