赵靖轩,巴振宁,阔晨阳,刘博佳. 2023. 2022年9月5日泸定MS6.8地震宽频带地震动谱元法模拟. 地震学报,45(2):179−195. doi: 10.11939/jass.20220190
引用本文: 赵靖轩,巴振宁,阔晨阳,刘博佳. 2023. 2022年9月5日泸定MS6.8地震宽频带地震动谱元法模拟. 地震学报,45(2):179−195. doi: 10.11939/jass.20220190
Zhao J X,Ba Z N,Kuo C Y,Liu B J. 2023. Broadband ground motion simulations applied to the Luding MS6.8 earthquake on September 5,2022 based on spectral element method. Acta Seismologica Sinica45(2):179−195. doi: 10.11939/jass.20220190
Citation: Zhao J X,Ba Z N,Kuo C Y,Liu B J. 2023. Broadband ground motion simulations applied to the Luding MS6.8 earthquake on September 5,2022 based on spectral element method. Acta Seismologica Sinica45(2):179−195. doi: 10.11939/jass.20220190

2022年9月5日泸定MS6.8地震宽频带地震动谱元法模拟

Broadband ground motion simulations applied to the Luding MS6.8 earthquake on September 5,2022 based on spectral element method

  • 摘要: 2022年9月5日12时52分四川甘孜州泸定县发生MS6.8地震,此次地震造成泸定县及其周边地域的严重破坏和人员的重大伤亡。为重现此次地震的地震动影响场,分析近场强地面运动的空间分布特征,将确定性的凹凸体震源模型与随机震源模型结合得到有限断层运动学混合震源模型,进而将上述混合震源模型开发到SPECFEM 3D谱元法开源代码中,实现了基于谱元法和运动学混合震源模型的泸定MS6.8地震的全过程宽频带(0.1—5 Hz)地震动模拟,通过与六个台站的时程记录、对应的反应谱以及NGA-West2地震动衰减曲线进行比较检验了方法的精度和适用性;进而给出了此次地震的三分量速度波场快照图,再现了地震波传播时近场地震动的方向性效应和局部场地效应;最后给出了震中100 km×100 km范围内的地震动峰值加速度(PGA)和峰值速度(PGV)云图,分析了泸定地震近场强地面运动的空间分布特征,并给出了基于模拟结果的地震烈度分布图。结果显示,震中PGA接近600 cm/s2,PGV接近50 cm/s,烈度达到Ⅸ度,且由于泸定地区内高山峡谷地形对地震动的影响,地震动峰值在山顶和峡谷处明显放大,山顶处PGA和PGV分别放大1.9倍和1.5倍,峡谷谷底处PGA和PGV分别放大1.7倍和1.4倍,这里出现的地震动放大现象以及可能造成的次生地质灾害亟需引起注意。

     

    Abstract: At 12:52 on September 5, 2022, a MS6.8 earthquake occurred in Luding County, Garze Prefecture, Sichuan Province. The earthquake caused severe damage and heavy casualties in Luding County and its surrounding areas. In order to reproduce the ground motion influence field of the earthquake and analyze the spatial distribution characteristics of near-field ground motion, the deterministic asperity source model is combined with the random source model to obtain the kinematic hybrid source model. Then, the hybrid source model is implemented into the SPECFEM 3D, and the whole-process broadband (0.1−5 Hz) ground motion simulation based on the spectral element method and kinematic hybrid source model is realized. The results from the simulation of Luding earthquake are as follows. Firstly, the simulation results are compared with the time history records of six stations, the corresponding response spectra and the NGA-West2 ground motion attenuation curves to test the applicability of the method. Secondly, the three-component velocity wavefield snapshots of the earthquake is given to demonstrate the directional effect and local site effect of the near field when the seismic wave propagates. Finally, the peak acceleration (PGA) and peak velocity (PGV) maps of the ground motion in the range of 100 km×100 km centered on the Luding area are given, and the spatial distribution characteristics of the ground motion in the near field region for the Luding earthquake are analyzed. Based on the simulation results, the seismic intensity distribution map is given. The results show that the epicenter PGA and PGV is close to 600 cm/s2 and 50 cm/s, respectively, and the seismic intensity reaches Ⅸ degree. Due to the influence of mountain-canyon topography in Luding area on the ground motion, the peak of ground motion is significantly amplified at the top of the mountain and the bottom of the canyon, with the amplification of PGA and PGV of 1.9 times and 1.5 times, respectively. The amplification of PGA and PGV at the bottom of the canyon is 1.7 times and 1.4 times. Therefore, attention should be paid to the phenomenon of earthquake amplification and possible secondary geological disasters in mountain-canyon region.

     

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