摘要:
2024-04-13阿里地区日土县Mw 5.6地震发生于青藏高原中西部的羌塘板块内部的鲁玛江冬错断裂附近，经测定其发震震中（81.884°E,33.585°N）位于当地一座海拔5 500 m左右的无名山峰附近。利用哨兵1号合成孔径雷达干涉测量（interferometric synthetic aperture radar,InSAR）数据量测了地震造成的同震地表形变场，联合使用非线性以及线性反演的方式确定了震源位置、几何参数，以及有限断层滑移模型。反演结果显示，这一次地震的发震断层走向约为336°，向东倾约66°，滑移分布矩心位置海拔超过5 435 m，是青藏高原内部近20年以来InSAR研究过的正断层地震中海拔最高的。通过滑移分布模拟的地表形变与当地地形的对比，发现这一处地震同震形变中的沉降集中在当地峰顶位置，呈现平整地貌的特征（即减小地形梯度），在一定程度上限制了山脉以及青藏高原继续隆起的趋势。这一次地震对于帮助人们认识正断层地震在高原地貌演化中的作用具有一定意义。
Abstract:
Objectives: This study aims to investigate the landscape evolution effects of the 2024 Mw 5.6 earthquake that occurred in Ritu County, Ali region, on the Tibetan Plateau using interferometric synthetic aperture radar (InSAR) observations. The research seeks to explore the geodynamic processes and the role of normal faulting earthquakes in the topographic development of the Tibetan Plateau. Methods: We utilized Sentinel-1 synthetic aperture radar data to capture the coseismic deformation field. Nonlinear and linear inversion methods were applied to determine the source location, geometric parameters, and finite fault slip distribution. The Okada model was used to calculate the three-dimensional coseismic deformation field, which was then compared with the local topography. Results: The inversion results revealed that the Ritu earthquake had a strike of 336°, a dip of 66° to the east, and a predominantly normal slip component with a minor right-lateral com ponent. The centroid of the slip distribution was located at an altitude of over 5 435 m, making it the highestaltitude normal faulting earthquake recorded by InSAR in the Tibetan Plateau interior over the past 20 years. The comparison between the coseismic deformation field and the local topography indicated that the subsidence was concentrated at the summit, flatten local topography by reducing the gradient, thereby limiting the continuous uplift of the Tibetan Plateau. Conclusions: The study concludes that the 2024 Ali earthquake, with its high epicentral elevation, played a significant role in restraining the further uplift of the Tibetan Plateau. The findings, to some extent, support the gravitational collapse theory of normal faulting earthquakes within the plateau and provide insights into the intrinsic mechanisms that prevent the Tibetan Plateau from continually uplifting. This research highlights the importance of high-altitude normal faulting earthquakes in shaping the landscape of the Tibetan Plateau.
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