2022年泸定Ms6.8级地震发震构造与鲜水河断裂带强震迁移规律

2022年9月5日12时52分在四川甘孜州泸定县发生Ms6.8级地震,震源深度16 km。这是继2014年康定地震后,发生在鲜水河断裂带上的又一次强震。笔者等通过已有文献资料,结合鲜水河断裂带南段野外地质调查,统计了滑动速率及历史地震资料,并总结了近代鲜水河断裂带强震迁移规律,对认识鲜水河断裂带活动特征及未来地震危险性具有重要意义。主要得出以下几点认识：①鲜水河断裂带各段滑动速率差异较大,以乾宁为界,从NW至SE段整体上呈现出“先减速后加速”的滑动特点;②泸定地震发震构造磨西断裂,为一次左旋走滑事件;③川滇地区近代历史强震活跃期具有“跳跃性”迁移的特点。自1981年道孚地震后,鲜水河断裂带断进入相对平静期,持续了33 a。自2014年康定地震发生,鲜水河断裂带再次进入地震活跃期;④鲜水河断裂带的强震破裂并非单次地震的“贯通型”模式,而是多次地震的渐进式。断层间相互作用尤其是大地震的发生对断裂带强震复发间隔具有重大影响,相同断裂带的强震也会对后续地震的发生概率产生变化。

Seismogenic structure of Luding M6. 8 earthquake in 2022 and strong earthquake migration law in Xianshuihe fault zone

In order to explore the seismogenic structure of the 2022 Luding magnitude 6. 8 earthquake and the migration patterns of strong earthquakes in the Xianshuihe fault zone. Methods: Based on existing literature and field geological surveys in the southern section of the Xianshuihe Fault Zone, this paper statistics the slip rate and historical earthquake data, and summarizes the migration patterns of strong earthquakes in the Xianshuihe Fault Zone in modern times, which is helpful for understanding the activities of the Xianshuihe Fault Zone. Characteristics and future seismic risk are of great significance. Results: The sliding rates of each section of the Xianshuihe fault zone are quite different; the seismogenic structure of the Luding earthquake was a left- lateral strike- slip event; the active period of strong earthquakes in the Sichuan—Yunnan region in modern history has the characteristics of “jumping” migration;Conclusions: ① The sliding rates of each section of the Xianshuihe fault zone are quite different. With Qianning as the boundary, the section from NW to SE shows a sliding characteristic of “first decelerating and then accelerating”. ② The seismogenic structure of the Luding earthquake The Moxi fault is a left- lateral strike- slip event. ③ The active period of strong earthquakes in the Sichuan and Yunnan regions in modern history has the characteristics of “jumping” migration. After the Daofu earthquake in 1981, the Xianshuihe fault zone entered a relatively quiet period, which lasted for 33 years. Since the Kangding earthquake in 2014, the Xianshuihe fault zone has once again entered a seismically active period. ④ The strong earthquake rupture of the Xianshuihe fault zone is not a “through- type” pattern of a single earthquake, but a gradual pattern of multiple earthquakes. The interaction between faults, especially the occurrence of large earthquakes, has a significant impact on the recurrence interval of strong earthquakes in the fault zone. Strong earthquakes in the same fault zone will also change the probability of subsequent earthquakes.