Institute of Earth Sciences, Academia Sinica, Taipei, 115, Taiwan.
Department of Geosciences, National Taiwan University, Taipei, 106, Taiwan.
Sci Rep. 2023 Mar 2;13(1):3552. doi: 10.1038/s41598-023-30361-0.
On 17-18 September 2022, an earthquake sequence with a moment magnitude of 6.6 foreshock and a 7.0 mainshock occurred in southeast Taiwan along the Longitudinal Valley. Several surface breaks and collapsed buildings were observed after the event and one person died. The focal mechanisms of the foreshock and mainshock both had a west-dipping fault plane, which is different from the known active east-dipping boundary fault between the Eurasian Plate and the Philippine Sea Plate. Joint source inversions were performed to better understand the rupture mechanism of this earthquake sequence. The results show that the ruptures mainly occurred on a west-dipping fault. In the mainshock, the slip originated from the hypocenter and propagated toward the north with a rupture velocity of approximately 2.5 km/s. The east-dipping Longitudinal Valley Fault also ruptured, which could be passive and dynamically triggered by the significant rupture on the west-dipping fault. Most importantly, this source rupture model together with the occurrence of large local earthquakes over the past decade strongly supports the existence of the Central Range Fault, which is a west-dipping boundary fault that lies along the north to south ends of the Longitudinal Valley suture.
2022 年 9 月 17-18 日，台湾东南部沿纵谷发生了一次矩震级为 6.6 的前震和 7.0 的主震地震序列。事件发生后，观察到多处地表破裂和建筑物倒塌，并有一人死亡。前震和主震的震源机制都有一个向西倾斜的断层面，与已知的欧亚板块和菲律宾海板块之间的活动东倾边界断层不同。进行了联合震源反演，以更好地了解该地震序列的破裂机制。结果表明，破裂主要发生在一个向西倾斜的断层上。在主震中，滑移从震源开始，向北传播，破裂速度约为 2.5 公里/秒。东倾的纵谷断层也发生了破裂，可能是由西倾断层上的显著破裂被动和动态触发的。最重要的是，这种震源破裂模型以及过去十年中发生的大型局部地震强烈支持中央山脉断层的存在，该断层是一条沿纵谷缝合带南北两端延伸的向西倾斜的边界断层。
