2022年四川泸定MS6.8地震震源破裂过程及强地面运动模拟

doi:10.12196/j.issn.1000-3274.2024.01.002

摘要/Abstract

摘要： 首先, 利用区域宽频带波形拟合, 反演了2022年泸定M_S6.8地震序列主震和部分余震的震源机制解和震源深度; 其次, 基于有限断层模型反演方法, 使用区域宽频带波形数据反演了此次泸定地震震源破裂过程, 并根据得到的震源破裂模型计算了峰值地面速度(PGV)分布。结果显示, 此次地震矩心深度为6.0 km, 是一个典型的高角度左旋走滑地震。震源破裂传播方向主要沿断层走向约165°向东南方向传播, 由深部震源起始破裂点向浅部扩展, 并破裂到地表, 地表破裂主要分布在磨西到猛虎岗一带, 长度约16 km。震源破裂过程持续时间约20 s, 能量主要集中在前15 s内释放。地震释放的标量地震矩为1.07×10¹⁹ N·m, 约等于矩震级M_W6.62。地震主体破裂发生在3~6 s之间, 最大滑动量达到1.8 m, 位于震中东南方向深度约10 km处。除此之外, 在震中西北方向深度11 km处和震中东南方向深度18 km处分别发生两个次级破裂, 滑动量大约在0.6~1.0 m。主体破裂的破裂长度约20 km, 两个次级破裂的长度分别约为4 km和8 km。使用该震源破裂模型计算得到了PGV分布, PGV分布以震中为中心沿断层走向两侧扩散, 其长轴与地震断层走向一致, 呈NW向, 极震区PGV为200~360 cm/s, 地震烈度区内受灾严重的村镇均位于极震区。

关键词: 2022年泸定M_S6.8地震, 震源机制解, 震源破裂过程, 峰值地面速度

Abstract: Firstly, we invert the focal mechanism solutions and source depths of the main shock and some aftershocks of the 2022 Luding M_S6.8 earthquake sequence using the regional broadband waveform fitting method. Secondly, we using the finite fault model inversion method and the regional broadband waveform data, the rupture model of the Luding earthquake is inverted, and the distribution of strong ground motion is calculated based on the obtained rupture model. The results show that the hypocenter depth of this earthquake is 6.0 km, and it is a typical high-angle left-lateral strike-slip earthquake. The direction of rupture propagation is mainly along the direction of the fault at about 165° to the southeast, starting from the epicenter and extending from the deep to the shallow part, and then rupturing to the surface. The surface rupture mainly occurred in the area from Moxi to Menghugang, with a length of about 16 km. The duration of the earthquake rupture process is about 20 s, and the energy is mainly released within the first 15 s. The seismic moment released is 1.07×10¹⁹ N·m, equivalent to a moment magnitude of M_W6.62. The main rupture occurred between 3~6 s, with a maximum slip of 1.8 m, located about 10 km deep in the southeast direction of the epicenter. In addition, there were two secondary ruptures at a depth of 11 km in the northwest direction from the epicenter and 18 km deep in the southeast direction, respectively, with a slip of about 0.6~1.0 m. The length of the main rupture is about 20 km, and the length of the two secondary ruptures is 4 km and 8 km, respectively. The distribution of peak ground velocity (PGV) is calculated using the obtained rupture model, and the PGV distribution spreads around the epicentre as the centre, its long axis is consistent with the direction of the earthquake intensity long axis, which is NW-oriented, and the peak ground velocity in the epicentral area is between 200~360 cm/s. The villages and towns that incurred substantial damage in the earthquake intensity zone are all located in the article's epicentre.

Key words: The 2022 Luding M_S6.8 earthquake, Focal mechanism, Source rupture process, Peak ground velocity

中图分类号:

P315.7

舒甜甜, 罗艳, 朱音杰. 2022年四川泸定M_S6.8地震震源破裂过程及强地面运动模拟[J]. 地震, 2024, 44(1): 19-36.

SHU Tian-tian, LUO Yan, ZHU Yin-jie. The Source Rupture Process and the Strong Ground Motion Estimation of the 2022 M_S6.8 Earthquake in Luding, Sichuan[J]. EARTHQUAKE, 2024, 44(1): 19-36.

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