Liu Jihong, Jónsson Sigurjón, Li Xing, Yao Wenqian, Klinger Yann
King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.
Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, Paris, France.
Nat Commun. 2025 Feb 3;16(1):1286. doi: 10.1038/s41467-025-56466-w.
Quantifying coseismic fault offsets for surface ruptures of major earthquakes is important for earthquake cycle and slip-rate studies, and thus for earthquake hazard assessments. However, measurements of such offsets generally underestimate fault slip due to inelastic deformation and secondary fault offsets, i.e., off-fault damage. Here, we use satellite synthetic aperture radar images to quantify off-fault damage in the two 2023 Kahramanmaraş (Türkiye) magnitude 7.8 and 7.6 earthquakes. We first derive three-dimensional coseismic surface displacements and show that on average ~35% of the coseismic slip is accommodated by off-fault damage within 5-7 km of the coseismic surface ruptures. Fault sections exhibiting geometrical complexities (e.g., bends and step-overs) experienced a higher level of off-fault damage than simpler fault sections. Our results highlight the importance of extending off-fault damage assessments to several km away from fault ruptures and indicate that fault offset measurements may underestimate slip-rate estimations by as much as a third.
对大地震的地表破裂进行同震断层错距量化，对于地震周期和滑动速率研究至关重要，因而对地震危险性评估也很重要。然而，由于非弹性变形和次生断层错距（即断层外损伤），此类错距的测量通常会低估断层滑动。在此，我们利用卫星合成孔径雷达图像，对2023年土耳其卡赫拉曼马拉什发生的两次7.8级和7.6级地震中的断层外损伤进行量化。我们首先得出三维同震地表位移，并表明，同震地表破裂5 - 7千米范围内，平均约35%的同震滑动是由断层外损伤来实现的。与较简单的断层段相比，呈现几何复杂性（如弯曲和阶跃）的断层段经历了更高程度的断层外损伤。我们的结果凸显了将断层外损伤评估扩展到距断层破裂数千米范围之外的重要性，并表明断层错距测量可能会使滑动速率估计值低估多达三分之一。
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