2022年9月台湾岛ML6.6和ML6.832次地震的破裂过程反演

doi:10.3969/j.issn.0253-4967.20240045

摘要/Abstract

摘要：

位于台湾岛东部的NNE向纵谷断裂是一条重要的构造边界带和强震活动带。2022年9月17日、 9月18日分别在纵谷断裂的南部发生了M_L6.6(M_W6.5)、 M_L6.83(M_W6.9)2次强震。根据台湾地区气象局(CWB)提供的地震信息可知2次地震的震中仅相距11km, 发震时间仅相隔17h, 而与9月17日的左旋走滑地震不同的是, 9月18日的地震为逆冲兼走滑地震。文中利用CWB提供的近场强震数据及定位结果, 基于美国地质调查局给出的震源参数, 采用迭代反褶积和叠加(Iterative Deconvolution and Stacking, IDS)方法研究了这2次地震的震源破裂过程和应力触发关系, 并利用地震波数据的高时间分辨率优势分离了这2次地震的同震形变场。结果显示: 2次地震的主破裂分别持续了27s和48s, 断层滑动分布分别呈现单驼峰和双驼峰的形状。9月17日地震的滑动分布集中在震中西南侧, 9月18日地震的滑动分布在震中东北侧, 为不对称的双侧破裂模式, 滑动分布的深度都在0~30km处, 2次地震的累积最大滑动量分别为1.06m和3.19m, 9月17日地震对9月18日地震产生了明显的应力触发作用。这种应力触发作用可能是导致2次地震在短时间内相继发生的重要原因之一。

关键词: 台湾岛, 地震震源破裂过程, 应力触发, 同震形变场

Abstract:

The Taiwan Island is located at the tectonic junction of the western Pacific subduction zone and the Eurasian continental margin, where complex plate subduction, collision, and strike-slip motions have collectively shaped the region’s intense tectonic activity and frequent seismic hazards. The NNE-trending Longitudinal Valley Fault(LVF) in eastern Taiwan serves as a major tectonic boundary separating the Eurasian Plate and the Philippine Sea Plate. It is also recognised as one of the world’s most renowned seismically active zones. On September 17 and 18, 2022, two destructive strong earthquakes with magnitudes of M_L6.6(M_W6.5)and M_L6.83(M_W6.9)successively occurred in the southern segment of this fault. According to high-precision seismic observations from “Taiwan’s Central Weather Bureau(CWB)”, the epicenters of the two events are only 11km apart, with a time interval of 17 hours, indicating significant spatiotemporal clustering. Notably, the focal mechanisms of the two earthquakes differ distinctly: the September 17 event was a typical left-lateral strike-slip earthquake, while the September 18 event displayed a more complex composite rupture mechanism dominated by thrust motion with a significant strike-slip component. This rapid transition in tectonic deformation modes within a short period reflects the complex stress environment of the region, providing a unique natural laboratory for revealing the fine-scale dynamic processes of the fault zone and the interaction mechanisms between consecutive earthquakes.

To systematically analyse the source rupture processes and stress triggering relationships of these two strong earthquakes, this study collected near-field strong-motion records and precise hypocenter locations from the CWB, combined with source parameters released by the United States Geological Survey(USGS). Using the Iterative Deconvolution and Stacking(IDS)technique, we performed detailed kinematic inversions of the rupture processes of both events. Furthermore, leveraging the high temporal resolution advantage of seismic waveform data, we successfully isolated the co-seismic deformation fields for each earthquake, providing crucial evidence for understanding the interaction mechanisms within the earthquake sequence. The inversion results show that the rupture durations of the two earthquakes are 27s and 48s, respectively, and that the spatial patterns of fault slip distribution are significantly different: the September 17 earthquake exhibited a single-peak slip distribution concentrated southwest of the epicenter, with a maximum slip of 1.06m. In contrast, the September 18 earthquake displayed a double-peak slip pattern predominantly distributed northeast of the epicenter, reaching a maximum slip of 3.19m and featuring a typical asymmetric bilateral rupture. The slip depths of both earthquakes are distributed within the range of 0-30km, consistent with regional seismotectonic characteristics.

Quantitative analysis of Coulomb failure stress changes demonstrated that the September 17 earthquake induced significant static stress perturbations in the rupture area of the September 18 event, exceeding the seismic triggering threshold. Our results strongly support the domain role of static stress transfer in this earthquake sequence. Further analysis revealed that the September 18 earthquake had a higher stress drop, which may be closely related to its complex rupture mechanism and larger slip magnitude.

Through high-resolution source rupture process inversion and Coulomb stress change calculation, this study systematically revealed the rupture differences, spatiotemporal evolution laws, and intrinsic triggering mechanisms of the short-time sequence strong earthquakes along the LVF in Taiwan, China. It not only confirms the importance of stress transfer between earthquakes but also highlights the complexity of seismic rupture processes(e.g., the diversity of rupture modes and the inhomogeneity of slip distribution). The findings provide important observational evidence for an in-depth understanding of seismic rupture behavior along the LVF, complex tectonic deformation mechanisms at plate boundaries, and the laws of earthquake generation and occurrence. Meanwhile, this study emphasizes the core significance of inter-earthquake interactions for earthquake prediction, hazard assessment, and disaster prevention and mitigation. Additionally, it provides a methodological reference for earthquake sequence research in similar tectonic environments. Future research should further integrate numerical simulations with multidisciplinary observational data to explore the physical mechanisms of seismic rupture processes. Simultaneously, in regions with high seismic hazard, such as Taiwan, China, it is necessary to continuously strengthen the development of high-density seismic network monitoring and multi-parameter early warning technologies, thereby continuously improving comprehensive prevention and control capabilities for seismic disasters and minimizing casualties and economic losses from earthquakes.

Key words: Taiwan Island, China, seismic source rupture mechanisms, stress trigger, coseismic deformation field

刘恋, 屈春燕, 吴东霖, 容伊霖, 陈晗. 2022年9月台湾岛M_L6.6和M_L6.832次地震的破裂过程反演[J]. 地震地质, 2026, 48(1): 217-232.

LIU Lian, QU Chun-yan, WU Dong-lin, RONG Yi-lin, CHEN Han. THE RUPTURE PROCESS INVERSION OF SEPTEMBER 2022 M_L6.6 AND M_L6.83 EARTHQUAKES IN TAIWAN ISLAND, CHINA[J]. SEISMOLOGY AND GEOLOGY, 2026, 48(1): 217-232.

图/表 13

图1 2022年中国台湾双震构造背景及余震分布内嵌图为中国台湾所处的大地构造位置及主要构造线和强震动台站分布

Fig. 1 Tectonic background and aftershock distribution of the 2022 double earthquakes in Taiwan, China.

表1 2022年9月2次台东地震震源参数

Table1 Source parameters of two Taitung earthquakes in September 2022

机构	发震时间 (UTC)	东经 /(°)	北纬 /(°)	震源深度 /km	走向 /(°)	倾角 /(°)	滑动角 /(°)	震级
CWB	2022-09-17,13:41:19.11	121.1608	23.084	8.61				M_L6.6
	2022-09-18,06:44:15.25	121.1958	23.137	7.81				M_L6.83
USGS	2022-09-17,13:41:17	121.414	23.119	10	202	63	13	M_W6.5
	2022-09-18,06:44:13	121.344	23.138	10	203	69	25	M_W6.9
本文	2022-09-17,13:41:19.11	121.1608	23.084	8.61	202	63	13	M_W6.8
	2022-09-18,06:44.15.25	121.1958	23.137	7.81	203	69	70	M_W7.2

图2 IDS方法震源破裂过程反演流程

Fig. 2 Inversion flow of source rupture process using IDS method.

图3 破裂过程反演所用的强震数据台站分布 a 原始强震数据台站分布; b 9月18日地震选取台站分布; c 9月17 日地震选取台站分布, 彩色背景为2次地震的断层模型

Fig. 3 Distribution of strong seismic data stations used for inversion of rupture process.

图4 2次地震的震源时间函数 a 震源时间过程, 红线和蓝线分别表示9月17日地震和9月18日地震的震源时间过程; b、 c 9月17日、 18日地震子断层的震源时间过程

Fig. 4 Source time function of two earthquakes.

图5 2次地震的累积滑动分布 a 将滑动分布投影到地表; b、 c 滑动分布在断层面上分布形态, 蓝色等值线为破裂扩展时间(s)

Fig. 5 Cumulative slip distribution of two earthquakes.

图6 2次地震的震源断层破裂过程随时间的累积变化左列为9月17日地震, 右列为9月18日地震

Fig. 6 Cumulative change over time of focal fault rupture process of two earthquakes.

图7 2次地震的震源断层破裂过程随时间的增量变化左列为9月17日地震, 右列为9月18日地震

Fig. 7 The incremental change in the source rupture process of two earthquakes over time.

图8 9月17日地震的观测波形和合成波形的拟合结果

Fig. 8 Fitting results of observed and synthetic waveforms for the earthquake on September 17.

图9 9月18日地震的观测波形和合成波形的拟合结果

Fig. 9 Fitting results of observed and synthetic waveforms for earthquake on September 18.

图10 采用地震波数据分离双震的InSAR形变场 a ALOS-2观测的双震形变场; b、 c 强震动模拟的9月17日地震形变场及其与观测的双震形变场(图a)的差值; e、 f 强震动模拟的9月18日地震形变场及其与观测的双震形变场(图a)的差值; d ALOS-2观测的9月18日地震的形变场(Tang et al., 2023)

Fig. 10 InSAR deformation field of double earthquakes separated by seismic wave data.

图11 2022年9月17日地震引起的2022年9月18日地震发震断层面上的同震库仑应力变化白色实线表示1~3MPa以0.5MPa为间隔的库仑应力变化等值线, 灰色实线为阈值为0.01MPa的库仑应力变化的位置

Fig. 11 Coseismic Coulomb stress changes on the fault surface of the September 18, 2022 earthquake caused by the September 17, 2022 earthquake.

图12 双震的库仑应力对周围地区的库仑应力影响

Fig. 12 Influence of the Coulomb stress on the surrounding area caused by the two earthquakes.

参考文献 22

[1]	胡晓斌. 2024. GPS约束下的2022年台湾 M_W6.9 地震破裂滑动分布[J]. 大地测量与地球动力学, 44(2): 173—76.
	HU Xiao-bin. 2024. Inversion for the slip distribution of the 2022 Taiwan M_W6.9 earthquake based on GPS displacements[J]. Journal of Geodesy and Geodynamics, 44(2): 173—176 (in Chinese).
[2]	黄少华, 万永革, 冯淦, 等. 2023. 2022年9月17日中国台湾地震序列的触发机制及其动力学成因[J]. 地质力学学报, 29(5): 674—684.
	HUANG Shao-hua, WAN Yong-ge, FENG Gan, et al. 2023. Trigger mechanism and dynamic causes of the Taiwan earthquake sequence on September 17, 2022[J]. Journal of Geomechanics, 29(5): 674—684 (in Chinese).
[3]	张勇, 许力生, 陈运泰. 2015. 2015年尼泊尔 M_W7.9 地震破裂过程: 快速反演与初步联合反演[J]. 地球物理学报, 58(5): 1804—1811.
	ZHANG Yong, XU Li-sheng, CHEN Yun-tai. 2015. Rupture process of the 2015 Nepal M_W7.9 earthquake: Fast inversion and preliminary joint inversion[J]. Chinese Journal of Geophysics, 58(5): 1804—1811 (in Chinese).
[4]	Chang K J, Taboada A, Chan Y C. 2005. Geological and morphological study of the Jiufengershan landslide triggered by the Chi-Chi Taiwan earthquake[J]. Geomorphology, 71(3-4): 293—309.
[5]	Chen K H, Toda S, Rau R. 2008. A leaping, triggered sequence along a segmented fault: The 1951 M_L7.3 Hualien-Taitung earthquake sequence in eastern Taiwan[J]. Journal of Geophysical Research: Solid Earth, 113(B2): 2007JB005048.
[6]	Chen K P, Tsai Y B. 2008. A catalog of Taiwan earthquakes(1900—2006) with homogenized M_W magnitudes[J]. Bulletin of the Seismological Society of America, 98(1): 483—489.
[7]	Ching K, Rau R, Zeng Y. 2007. Coseismic source model of the 2003 M_W6.8 Chengkung earthquake, Taiwan, determined from GPS measurements[J]. Journal of Geophysical Research: Solid Earth, 112(B6): 2006JB004439.
[8]	Deng J, Sykes L R. 1997. Evolution of the stress field in southern California and triggering of moderate-size earthquakes: A 200-year perspective[J]. Journal of Geophysical Research: Solid Earth, 102(B5): 9859—9886.
[9]	Hsu Y, Yu S, Simons M, et al. 2009. Interseismic crustal deformation in the Taiwan plate boundary zone revealed by GPS observations, seismicity, and earthquake focal mechanisms[J]. Tectonophysics, 479(1-2): 4—18.
[10]	Laske G, Masters G, Ma Z et al. 2013. Update on CRUST1.0: A 1-degree global model of earth’s crust[C]. Geophysics research abstracts, 15, Abstract EGU2013-2658, 2013, Vienna, Austria.
[11]	Lee S, Liu T, Lin T. 2023. The role of the west-dipping collision boundary fault in the Taiwan 2022 Chihshang earthquake sequence[J]. Scientific Reports, 13(1): 3552.
[12]	Lee S, Lin T, Liu T, et al. 2019. Fault-to-fault jumping rupture of the 2018 M_W6.4 Hualien earthquake in eastern Taiwan[J]. Seismological Research Letters, 90(1): 30—39.
[13]	Seeber L, Armbruster J G. 2000. Earthquakes as beacons of stress change[J]. Nature, 407(6800): 69—72.
[14]	Tang C, Lin Y, Tung H, et al. 2023. Nearby fault interaction within the double-vergence suture in eastern Taiwan during the 2022 Chihshang earthquake sequence[J]. Communications Earth & Environment, 4(1): 333.
[15]	Toda S, Lin J, Meghraoui M, et al. 2008. 12 May 2008 M=7.9 Wenchuan, China, earthquake calculated to increase failure stress and seismicity rate on three major fault systems[J]. Geophysical Research Letters, 35(17): 2008GL034903.
[16]	Wang R, Lorenzo-Martín F, Roth F. 2006. PSGRN/PSCMP: A new code for calculating co- and post-seismic deformation, geoid and gravity changes based on the viscoelastic-gravitational dislocation theory[J]. Computers & Geosciences, 32(4): 527—541.
[17]	Wang W, Chen C. 2001. Static stress transferred by the 1999 Chi-Chi, Taiwan, earthquake: Effects on the stability of the surrounding fault systems and aftershock triggering with a 3D fault-slip model[J]. Bulletin of the Seismological Society of America, 91(5): 1041—1052.
[18]	Wu Y, Chang C, Zhao L, et al. 2008. A comprehensive relocation of earthquakes in taiwan from 1991 to 2005[J]. Bulletin of the Seismological Society of America, 98(3): 1471—1481.
[19]	Yagi Y, Okuwaki R, Enescu B, et al. 2023. Irregular rupture process of the 2022 Taitung, Taiwan, earthquake sequence[J]. Scientific Reports, 13(1): 1107.
[20]	Yu S, Chen H, Kuo L. 1997. Velocity field of GPS stations in the taiwan area[J]. Tectonophysics, 274(1-3): 41—59.
[21]	Zhang Y, Wang R, Chen Y. 2015. Stability of rapid finite-fault inversion for the 2014 M_W6.1 South Napa earthquake[J]. Geophysical Research Letters, 42(23),: 10263—10272.
[22]	Zhang Y, Wang R, Zschau J, et al. 2014. Automatic imaging of earthquake rupture processes by iterative deconvolution and stacking of high-rate GPS and strong motion seismograms[J]. Journal of Geophysical Research: Solid Earth, 119(7): 5633—5650.