Dynamic deformation and fault locking of the Xianshuihe Fault Zone, Southeastern Tibetan Plateau: implications for seismic hazards
Dynamic deformation and fault locking of the Xianshuihe Fault Zone, Southeastern Tibetan Plateau: implications for seismic hazards
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青藏高原东南部鲜水河断裂带的动态变形和断锁：对地震灾害的影响
DOI：
10.1186/s40623-022-01591-9
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发表时间：
2021-08
期刊：
影响因子：
--
通讯作者：
Xinzhong Liu
中科院分区：
文献类型：
--
作者：
Layue Li;Yanqiang Wu;Yujiang Li;Wei Zhan;Xinzhong Liu
鲜水河断裂带是中国大陆历史上地震活动最活跃的地区之一。然而，自1981年道孚6.9级地震以来，该断裂带的地震活动在过去的40年里一直处于停滞状态。了解其现今的形变规律和断层耦合特征，对预测强震的潜在危险性具有重要意义。利用全球导航卫星系统(GNSS)1999-2007年和2016-2020年的观测数据，分析了鲜水河断裂带的动态形变和断层耦合特征。结果表明，2008年汶川7.9级和2013年庐山6.6级地震后鲜水河断裂带的变形格局发生了动态调整，即炉霍和道孚断裂带的最大剪切应变累积速率从6.0×10-8/a显著下降到3.2×10-8/a，而东南段(康定和磨溪段)的最大剪切应变累积速率从4.5×10-8/a增加到6.2×10-8/a，鲜水河断裂带的滑动速率和变形宽度在这两个时期也发生了变化。结合近场跨断层观测资料，认为周边强震汶川、庐山对鲜水河断裂带的形变格局有明显的差异性影响。断层耦合反演结果表明，汶川地震和庐山地震后鲜水河断裂带的闭锁程度持续增加，特别是乾宁和磨溪断裂带的闭锁程度显著增加，平均耦合系数大于0.9，左旋滑动速率差分别为~5 mm/a和~8 mm/a。相比之下，康定段的闭锁程度降低，几乎没有滑移率赤字，处于爬行状态。鲜水河断裂带近期破裂历史和应变积累特征分析表明，乾宁段和磨溪段对鲜水河断裂带的下一次强震都具有很高的地震潜力。图形摘要
AbstractThe Xianshuihe Fault Zone is one of the most historically seismically active regions in mainland China. However, the seismicity along this fault zone has been quiescent for the past 40years, since the Daofu M6.9 earthquake in 1981. Understanding its current deformation patterns and fault coupling characteristics is of great significance to estimate the potential risk of strong earthquakes. In this study, we analyzed the dynamic deformation and fault coupling characteristics along the Xianshuihe Fault Zone using Global Navigation Satellite System (GNSS) data for 1999–2007 and 2016–2020. The results show that the deformation pattern of the Xianshuihe fault zone underwent a dynamic adjustment after the 2008Wenchuan Mw7.9and 2013LushanMw6.6 earthquakes, i.e., the maximum shear strain accumulation rates of the Luhuo and Daofu sections significantly decreased from 6.0 × 10–8/a to 3.2 × 10–8/a, while that of the southeastern segment (i.e., Kangding and Moxi sections) increased from 4.5 × 10–8/a to 6.2 × 10–8/a. Additionally, the slip rate and deformation width of the Xianshuihe Fault Zone also changed during these two periods. Combined with the near-field cross-fault observation data, we suggest that the surrounding strong earthquakes Wenchuan and Lushan had evident differential impacts on the deformation pattern of the Xianshuihe Fault Zone. The fault-coupling inversion results show that the locking degree of the Xianshuihe Fault Zone continued to increase after the Wenchuan and Lushan earthquakes, especially the Qianning and Moxi sections increased significantly, with an average coupling coefficient of greater than 0.9 and left-lateral slip-rate deficits of ~ 5mm/a and ~ 8mm/a, respectively. In contrast, the locking degree of the Kangding section decreased with almost no slip-rate deficit, which is in a state of creeping status. The analysis of the recent rupture history and strain accumulation characteristics of the Xianshuihe Fault Zone indicates that both the Qianning and Moxi sections have a high seismic potential for the next strong earthquake in the Xianshuihe Fault Zone.. Graphical Abstract
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