鲜水河断裂带地震矩亏损的空间分布及2022年泸定<i>M</i> 6.8级地震

尹力; 周本刚; 任治坤; 罗纲

doi:10.3799/dqkx.2023.138

鲜水河断裂带地震矩亏损的空间分布及2022年泸定M 6.8级地震

doi: 10.3799/dqkx.2023.138

尹力^1, ,,
周本刚¹,
任治坤¹,
罗纲²

1.
中国地震局地质研究所, 地震动力学国家重点实验室, 北京 100029
2.
武汉大学测绘学院, 湖北武汉 430079

基金项目:

国家重点研发计划项目 2022YFC3003501

中国地震局地质研究所基本科研业务专项 IGCEA2315

国家自然科学基金青年项目 41904089

详细信息

作者简介:
尹力（1989-），男，副研究员，博士，主要从事断层活动及地震循环的岩石圈变形过程的有限元数值模拟、地震活动特征及危险性分析. ORCID：0000-0003-0850-6930. E-mail：yinli2022@ies.ac.cn

中图分类号: P315
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出版历程
- 收稿日期: 2023-02-11
- 刊出日期: 2024-02-25

Spatial Distribution of Seismic Moment Deficit in Xianshuihe Fault Zone and the 2022 Luding M 6.8 Earthquake

1.
State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China
2.
School of Geomatics, Wuhan University, Wuhan 430079, China

摘要

摘要: 2022年9月5日泸定M 6.8级地震发生在鲜水河断裂带南端的磨西断裂. 该地震的发震机制以及未来该断裂段是否仍会发生强震是值得关注的科学问题.拟从地震能量积累与释放的角度来解释该地震的发震原因以及鲜水河断裂带未来的发震潜力. 通过对比地震矩积累与释放的时空分布，发现地震大都发生在地震矩亏损的段落，并有填补地震矩亏损的趋势. 此外，鲜水河断裂带至今存在3个显著的地震矩亏损段，均具发生6.5级以上地震的潜力. 1786年康定M 7.6级地震发生之后，经过两百多年时间的积累，足以发生M 6.5级以上地震，而泸定M 6.8级地震仅释放了磨西断裂上部分的地震矩亏损，未来该断裂段仍具有发生强震的可能.
- 地震矩亏损 /
- 鲜水河断裂带 /
- 泸定M 6.8级地震 /
- 地震危险性分析
Abstract: On September 5, 2022, an M6.8 earthquake located at the Moxi fault at the southern end of the Xianshuihe fault zone. The seismogenic mechanism of this earthquake and whether large earthquakes will occur in this fault section in the near future are scientific issues worth attention. This paper attempts to explain the seismogenic mechanism of the earthquake and the potential seismogenic potential of the Xianshuihe fault zone in the future from the perspective of the accumulation and release of seismic energy. By comparing the temporal and spatial distribution of seismic moment accumulation and release, it is found that earthquakes mostly occur in the period of seismic moment deficit, and there is a tendency to fill the moment deficit. In addition, there are three significant moment deficit segments in Xianshuihe fault zone. All of these moment deficit fault segments have the potential to produce earthquakes of magnitude 6.5 or greater. After the 1786 Kangding M 7.6 earthquake, the accumulation of 200 years is enough to produce an earthquake of M 6.5 or above. The Luding M 6.8 earthquake only released a small part of the moment deficit on the Moxi fault, and there is still a possibility of a major earthquake on this fault section in the future.
- moment deficit /
- Xianshuihe fault zone /
- Luding M 6.8 earthquake /
- seismic hazard assessment
注释:

1) 附件见本刊官网：http://www.earth-science.net.

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图 1 鲜水河断裂带的断层及地震分布图

Fig. 1. Distribution of faults and earthquakes on the Xianshuihe fault zone

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图 2 鲜水河断裂带内地震记录的Gutenberg-Richter估计

由开源代码ZMAP绘制；Wiemer（2001）；M_c为最小完备震级，红色方点为各震级的频度，灰色方点为累积的地震频度

Fig. 2. The Gutenberg-Richter distribution of seismic events in the Xianshuihe fault zone

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图 3 GPS速度场（相对于稳定的华南块体）

数据来自Wang and Shen（2020）. 红色虚线围限的多边形区域是拟分析的地震带.

Fig. 3. GPS velocity field (with respect to the stable south China block)

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图 4 GPS速度和应变率场

a.GPS站点相对于稳定华南的速度（紫色箭头）和连续速度场（底图色）；b. 应变率（应变率张量的第二不变量，底图色）和主应变率（红棒为拉应变率，黑棒为压应变率）；红色虚线围限的多边形区域定义了拟分析地震带的范围.

Fig. 4. GPS velocity field and strain rate field

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图 5 地震矩积累与释放的对比

通过大地震（M > 6.0；橙色点）的Kostrv矩求和计算的累积地震矩（红线），红色虚线为考虑M 6.0级以下地震的校正结果. 大地测量方法获得的地震矩积累由灰线（自1500年至今）表示，灰色虚线考虑了发震地壳厚度H及Wt的不确定性. 绿线显示自1620年至今的地震矩积累

Fig. 5. Comparison of moment accumulated and release rates

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图 6 沿鲜水河断裂带地震矩积累与释放的对比

a. 鲜水河断裂带的断层轨迹（黑色实线）及主要地震事件的时空分布（M_W > 6.0），从下到上按时间顺序排列，显示为水平灰色线条，其地震破裂长度取决于震级；红色线条为泸定6.8级地震；b.沿鲜水河断裂带的地震矩积累和释放的对比

Fig. 6. Comparison of moment accumulated and release along the Xianshuihe fault zone

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图 7 沿鲜水河断裂带地震矩亏损的空间分布

a.假设1500年的应变水平为0，颜色区域显示了沿鲜水河断裂带的地震矩亏损的空间分布；灰色虚线为误差范围；b. 沿鲜水河断裂带24 km（M_W 6.5）、50（M_W 7.0）和94（M_W 7.4）的移动空间窗口内累积的地震矩亏损. 灰色虚线为不同震级对应的地震矩；LMW. 空间窗口的长度

Fig. 7. Moment deficit along the Xianshuihe fault zone

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图 8 康定-磨西段以1786年为起点的地震矩亏损及地震危险性

a. 假设1786年的应变水平为0，颜色区域显示了沿鲜水河断裂带的地震矩积累与释放的空间分布；灰色虚线为地震矩积累的误差范围；b. 沿鲜水河断裂带24 km（M_W 6.5）、50（M_W 7.0）和94 km（M_W 7.4）的移动空间窗口内累积的地震矩亏损；灰色虚线为不同震级对应的地震矩；LMW. 空间窗口的长度.

Fig. 8. Moment deficit and seismic hazards along the Kangding-Moxi segment from 1786

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表 1 自1500年以来鲜水河断裂带上历史和仪器记录的大地震（M > 6.0）

Table 1. Large earthquakes (M > 6.0) of the historic and recorded seismic catalogs on the Xianshuihe fault

年份	经度(ºE)	纬度(ºN)	断层段	M_S	M_W	破裂长度⁽¹⁾ (km)	M₀ (10¹⁸ Nm)
2022	102.08	29.59	磨西	6.80	6.700	25	12.60
2014	101.68	30.29	康定	6.30	6.000	30⁽²⁾	1.15
1981	101.15	30.95	道孚	6.90	6.520	45	6.85
1973	100.52	31.50	炉霍	7.60	7.100	90	46.77
1967	100.20	31.62	炉霍	6.80	6.350	18	3.71
1955	101.84	30.03	康定	7.50	7.370	35	127.35
1923	100.90	31.17	道孚	7.30	7.160	60	61.24
1919	101.07	31.00	道孚	6.25	6.300	22⁽³⁾	2.80
1904	101.00	31.06	道孚	7.00	6.840	55	20.42
1893	101.37	30.70	康定	7.00	6.840	70	20.42
1816	100.75	31.29	道孚	7.50	7.370	60	127.35
1811	100.15	31.61	炉霍	6.75	6.635	45	10.06
1793	101.33	30.75	乾宁	6.50	6.450	35	5.31
1792	101.00	31.06	乾宁	6.75	6.635	45	10.06
1786	102.04	29.87	康定	7.75	7.635	90	318.05
1748	101.62	30.33	康定	6.50	6.450	35	5.31
1747	100.85	31.23	道孚	6.75	6.635	45	10.06
1725	101.83	30.16	康定	7.00	6.840	50	20.42
1700	101.79	30.36	康定	6.50	6.450	35	5.31
注：(1) Wen et al.(2008); (2) 易桂喜等(2015); (3) 震级-破裂长度经验公式估计(Wells and Coppersmith, 1994).

下载: 导出CSV

表 2 应变率及地震矩积累速率($ {\dot{\boldsymbol{M}}}^{\boldsymbol{G}} $)的计算

Table 2. Calculation of strain rate and moment accumulated rate ($ {\dot{\boldsymbol{M}}}^{\boldsymbol{G}} $)

区域	面积 (10¹⁰ m²)	应变率(10^-9/a)	H (10³ m)	μ (10¹⁰ N/m²)	$ {\dot{M}}^{G} $ (10¹⁷ Nm/a)
鲜水河	5.57	$ 39.{3}_{-3.7}^{+5.6} $	17 ±3	3	$ 22.{4}_{-5.7}^{+7.7} $
注：H是断层带的深度；μ是断层的剪切模量；计算应变率场时Wt为18，Wt的不确定范围为±6.

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