Liu Jiao, Huang Chuanchao, Zhang Guohong, Shan Xinjian, Korzhenkov Andrey, Taymaz Tuncay
State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing, 100029, China.
School of Geosciences and Info-Physics, Central South University, Changsha, 410000, China.
Sci Rep. 2024 May 9;14(1):10625. doi: 10.1038/s41598-024-61326-6.
On February 6, 2023, an Mw 7.9 earthquake occurred in the western section of the East Anatolia Fault Zone (EAFZ). It was subsequently followed by an Mw 7.7 earthquake on the northern branch of the EAFZ, known as the Sürgü Fault Zone. Coseismic deformation fields were derived for these earthquakes using joint evaluation of near-field strong motion data, Global Navigation Satellite System data, and Synthetic Aperture Radar datasets. The coseismic slip distribution model was determined through the joint kinematic finite fault inversion. The Mw 7.9 earthquake was a left-lateral strike-slip event, predominantly occurring at depths up to 20 km. The earthquake displayed three distinct asperities that correlate well with bends and stepovers along the EAFZ. The Mw 7.7 earthquake also exhibited left-lateral strike-slip characteristics, with a major asperity along the Çardak Fault featuring a maximum slip of approximately 9.5 m at depths between 0 and 24 km. The occurrence of this unanticipated large Mw 7.9 catastrophic seismic event on a fault with low-intermediate structural maturity is noteworthy. In the vicinity of immature faults with multiple jogs, stress tends to accumulate at barrier locations. When the accumulated stress near several adjacent barriers reaches a certain threshold, it may result in the transformation of multiple barriers into asperities, triggering cascading ruptures.
2023年2月6日，东安纳托利亚断裂带（EAFZ）西段发生了一次矩震级7.9级的地震。随后，在EAFZ的北支（即叙尔居断裂带）发生了一次矩震级7.7级的地震。利用近场强震数据、全球导航卫星系统数据和合成孔径雷达数据集的联合评估，得出了这些地震的同震变形场。通过联合运动学有限断层反演确定了同震滑动分布模型。矩震级7.9级的地震是一次左旋走滑事件，主要发生在深度达20千米处。该地震显示出三个明显的asperities，与EAFZ沿线的弯曲和阶区有很好的相关性。矩震级7.7级的地震也表现出左旋走滑特征，沿恰尔达克断层有一个主要的asperity，在深度0至24千米之间最大滑动约为9.5米。在一个结构成熟度为中低的断层上发生这次意外的矩震级7.9级灾难性地震事件值得关注。在有多个拐点的未成熟断层附近，应力往往会在障碍位置积累。当几个相邻障碍附近积累的应力达到一定阈值时，可能会导致多个障碍转变为asperities，引发连锁破裂。
