2019年四川长宁MS6.0地震前破裂区内视应力和b值的变化

陈学忠; 李艳娥; 宫悦; 陈丽娟

doi:10.3969/j.issn.2096-7780.2021.02.001

2019年四川长宁M_S6.0地震前破裂区内视应力和b值的变化

doi: 10.3969/j.issn.2096-7780.2021.02.001

1.
中国地震局地球物理研究所，北京 100081
2.
四川省地震局，成都 610041
3.
重庆市地震局，重庆 401147

基金项目: 国家重点研发计划（2018YFC1503405）资助。

详细信息

通讯作者:
陈学忠（1963-），男，研究员，主要从事地震学与地震预测研究。E-mail：cxz8675@163.com

中图分类号: P315.72⁺7
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- 文章访问数: 376
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- PDF下载量: 49
出版历程
- 收稿日期: 2020-09-24
- 修回日期: 2020-09-28
- 网络出版日期: 2021-03-02
- 刊出日期: 2021-02-25

Variations in apparent stress and b value in the rupture area before the 2019 M_S6.0 Changning earthquake

1.
Institute of Geophysics，China Earthquake Administration，Beijing 100081，China
2.
Sichuan Earthquake Agency，Chengdu 610041，China
3.
Chongqing Earthquake Agency，Chongqing 401147，China

摘要

摘要: 视应力和b值都可以反映地壳应力变化。当应力增加时，视应力会增加，而b值降低。因此，应力变化将导致视应力和b值之间呈负相关关系，即，根据视应力和b值之间的负相关关系可以研究地壳构造应力的变化。本文利用2000年1月—2019年12月长宁M_S6.0地震破裂区内3.0≤M_L≤3.6地震的视应力和2.0≤M_L≤4.3地震目录，研究了视应力和b值随时间的变化，发现：2013年2月—2017年3月间，视应力呈趋势上升变化，历时约4年，在震前两年时间内，视应力仍维持在较高水平。在视应力呈趋势上升变化期间，b值则呈趋势下降变化。当视应力维持在较高水平时，b值则维持在较低水平。即，长宁M_S6.0地震发生前，破裂区内视应力增加，同时b值下降。这表明，2019年长宁M_S6.0地震发生前破裂区内存在明显的构造应力增加过程，对地震孕育过程的认识和地震预测研究都具有启示意义。
- 长宁M_S6.0地震 /
- 视应力 /
- b值 /
- 破裂区
Abstract: Both apparent stress and b value can reveal stress changes in the crust. As the stress increases, the apparent stress increases and the b value decreases. Therefore, the stress variation could result in a negative correlation between apparent stress and b value so that the variation of crustal tectonic stress can be investigated according to this negative correlation. In present study, on the basis of apparent stresses for earthquakes （3.0≤M_L≤3.6）and earthquakes （2.0≤M_L≤4.3）occurring in the aftershock region of the 2019 M_S6.0 Changning earthquake from January 2000 to December 2019, we analyzed the temporal evolutions of the apparent stress and b value. It was found that from February 2013 to March 2017, the apparent stress showed a rising trend lasting for about 4 years. Within the two years before the earthquake, the apparent stress remained at a higher level. During the period when the apparent stress was increasing, b value was decreasing. When the apparent stress maintained at a higher level, b value maintained at a lower level with no distinct change. That is, before the Changning M_S6.0 earthquake occurred, the apparent stress in the rupture zone increased, while the b value decreased. It indicates that there is an obvious increase of the tectonic stress in the fracture zone before the M_S6.0 Changning earthquake, which has important implications for the understanding of earthquake gestation process and earthquake prediction.
- Changning M_S6.0 earthquake /
- apparent stress /
- b value /
- rupture area

HTML全文

图 1 （a）长宁地震余震空间分布（2019年6月17日—7月31日，M_L≥0.0）以及全球质心矩张量解（沙滩球，箭头表示断层面错动方向）；（b）长宁地震以及历史上发生的M_S≥6.0地震（“○”）。F₁：华蓉山断裂带；F₂：马边—盐津断裂带；F₃：莲峰断裂带；F₄：峨边—金阳断裂带。 “☆”为长宁地震震中

Figure 1. （a）Spatial distribution of epicenters of M_L≥ 0.0 aftershocks that occurred from June 17，2019 to July 31，2019 and the GCMT solution for the June 17，2019 Changning M_S6.0 earthquake（beach ball，arrows indicate the slipping direction of the focal fault） . F₁ indicates the Huarongshan fault；F₂ indicates the Mabian-Yanjin fault；F₃ indicates the Lianfeng fault and F₄ indicates the Ebian-Jinyang fault. The star shows the epicenter of the Changning earthquake

下载: 全尺寸图片幻灯片

图 2 视应力与震级的关系

Figure 2. Apparent stress versus magnitude

下载: 全尺寸图片幻灯片

图 3 研究区内M_L≥1.0地震震级随时间变化

Figure 3. Magnitude versus time for earthquakes（M_L≥1.0）that occurred in the study area

下载: 全尺寸图片幻灯片

图 4 不同时期地震的G-R关系

Figure 4. The G-R relation of earthquakes in different periods

下载: 全尺寸图片幻灯片

图 5 视应力随时间的变化

（a）以20个地震计算平均值，2个地震滑动；（b）以30个地震计算平均值，2个地震滑动

Figure 5. Apparent stress as a function of time

（a）20-event mean，shifted by two events per time；（b）30-event mean，shifted by two events per time

下载: 全尺寸图片幻灯片

图 6 b值（黑色实线）随时间的变化。以400次地震为滑动窗口计算b值，20次地震滑动。 “↓”标注长宁M_S6.0地震发生时间。 “○”为视应力的30个事件平均值

Figure 6. b value（the black solid line）as a function of time obtained by applying a sliding time window of 400 events moved by 20 events. The down arrow“↓” shows the original time of the Changning M_S6.0 main event. The circle “○” denotes the 30-event mean of the apparent stress

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表 1 地震矩、地震能量和视应力计算结果

Table 1. Calculated seismic moment，seismic energy and apparent stress for the studied earthquakes

序号	年-月-日	纬度/°N	经度/°W	M_L	地震矩/（×10¹⁵ N•m）	E_s/（×10¹¹ N•m）	σ_app/bar
1	2002-04-29	28.42	104.70	3.8	1.70000	0.04940	0.82
2	2003-03-08	28.37	104.80	3.2	0.31500	0.00992	0.97
3	2003-06-23	28.47	104.80	3.4	0.36500	0.00615	0.45
4	2005-02-05	28.32	104.93	3.2	0.19700	0.00475	0.57
5	2005-12-19	28.27	104.97	3.5	0.46800	0.01510	0.88
6	2006-04-02	28.37	105.02	3.4	0.28200	0.00463	0.36
7	2006-04-28	28.38	104.88	3.0	0.14900	0.00303	0.36
8	2006-07-12	28.37	104.88	3.0	0.09780	0.00066	0.18
9	2006-08-01	28.33	104.98	3.9	2.22000	0.17300	1.69
10	2006-08-01	28.27	104.98	4.0	3.01000	0.24200	2.09
11	2006-08-25	28.38	104.85	3.0	0.09770	0.00040	0.12
12	2006-08-27	28.35	104.97	3.0	0.19800	0.00614	0.56
13	2006-10-30	28.33	104.92	3.3	0.28900	0.00498	0.42
14	2006-10-02	28.33	104.90	3.1	0.19600	0.00338	0.42
15	2006-10-30	28.33	104.92	3.3	0.29100	0.00500	0.41
16	2006-11-24	28.30	104.92	3.0	0.17000	0.00183	0.26
17	2007-01-04	28.37	104.95	3.8	1.13000	0.08600	1.83
18	2007-01-11	28.33	104.87	3.4	0.47900	0.01740	0.81
19	2007-01-27	28.35	105.03	3.4	0.43700	0.01400	0.65
20	2007-03-12	28.37	104.98	3.4	0.34800	0.00541	0.36
21	2007-04-22	28.32	104.92	3.6	0.65100	0.02610	0.93
22	2007-04-23	28.35	104.90	3.4	0.40100	0.01190	0.70
23	2007-04-24	28.40	105.00	3.3	0.52900	0.01330	0.58
24	2007-04-25	28.33	104.95	3.6	0.63200	0.02440	0.92
25	2007-05-08	28.33	105.00	3.4	0.43900	0.01140	0.73
26	2007-05-10	28.30	104.93	3.0	0.10800	0.00096	0.21
27	2007-05-31	28.33	104.98	3.2	0.22200	0.00451	0.38
28	2007-06-18	28.35	104.85	3.9	1.32000	0.13600	2.10
29	2007-06-19	28.32	104.95	3.2	0.19200	0.00324	0.35
30	2007-06-19	28.30	104.95	3.1	0.16100	0.00139	0.23
31	2007-06-19	28.28	104.95	3.8	0.72000	0.04040	1.32
32	2007-08-08	28.30	104.95	3.6	0.94800	0.06620	1.54
33	2007-08-14	28.30	104.92	4.1	2.50000	0.34700	3.53
34	2007-08-14	28.30	104.92	3.6	0.52200	0.02570	1.19
35	2007-08-16	28.30	104.90	3.8	1.12000	0.08000	1.88
36	2007-08-29	28.50	104.77	3.2	0.13000	0.00097	0.19
37	2007-09-13	28.32	104.88	3.2	0.17900	0.00283	0.38
38	2007-09-17	28.30	104.90	3.1	0.16900	0.00260	0.37
39	2007-09-22	28.33	104.88	3.1	0.25900	0.00433	0.39
40	2007-10-06	28.33	104.98	4.2	2.38000	0.33700	3.21
41	2007-10-10	28.33	104.92	3.1	0.09500	0.00076	0.26
42	2007-10-12	28.37	104.88	3.4	0.14100	0.00216	0.43
43	2007-10-22	28.38	104.88	3.4	0.15600	0.00153	0.31
44	2007-10-22	28.37	104.87	3.2	0.08260	0.00062	0.23
45	2007-10-24	28.37	104.88	3.2	0.09460	0.00099	0.29
46	2007-10-24	28.38	104.88	3.4	0.09630	0.00096	0.28
47	2007-11-01	28.38	104.87	3.0	0.06190	0.00043	0.19
48	2007-11-11	28.38	104.88	3.9	0.76600	0.02600	0.91
49	2007-11-11	28.37	104.88	3.3	0.15000	0.00165	0.33
50	2008-02-01	28.33	104.88	4.8	6.09000	1.31000	5.82
51	2008-02-02	28.38	104.95	3.2	0.11300	0.00136	0.34
52	2008-02-05	28.37	104.85	3.2	0.07250	0.00068	0.28
53	2008-02-05	28.38	104.88	3.2	0.11600	0.00106	0.27
54	2008-02-14	28.37	104.83	3.8	0.47700	0.01720	0.94
55	2008-02-14	28.37	104.83	3.3	0.14800	0.00141	0.26
56	2008-02-20	28.48	104.73	3.4	0.14000	0.00169	0.30
57	2008-07-19	28.35	104.92	3.0	0.09600	0.00085	0.25
58	2008-08-29	28.37	104.88	3.8	0.21100	0.00441	0.60
59	2009-01-01	28.37	104.85	3.5	0.24200	0.00559	0.48
60	2009-06-10	28.33	104.88	3.4	0.33500	0.00971	0.78
61	2009-06-12	28.35	104.83	3.0	0.08640	0.00061	0.16
62	2009-11-27	28.37	104.88	3.0	0.08240	0.00089	0.31
63	2010-03-26	28.37	104.88	3.1	0.06990	0.00055	0.21
64	2010-07-16	28.42	104.88	4.0	0.72100	0.05110	2.04
65	2010-08-25	28.37	104.88	3.0	0.05210	0.00031	0.18
66	2010-10-01	28.37	104.90	3.2	0.12400	0.00153	0.28
67	2010-10-06	28.37	104.92	4.6	3.24000	0.88000	7.42
68	2010-10-24	28.37	104.88	3.2	0.11800	0.00212	0.51
69	2010-12-03	28.32	104.92	3.7	1.63000	0.21000	3.15
70	2011-04-30	28.37	104.92	3.8	0.72500	0.05780	2.09
71	2011-04-30	28.35	104.92	3.4	0.37600	0.01600	1.03
72	2011-06-02	28.33	104.92	3.9	1.05000	0.08740	2.19
73	2011-06-26	28.37	104.92	4.3	1.79000	0.18800	2.78
74	2011-10-05	28.35	104.88	3.3	0.17900	0.00195	0.31
75	2012-04-09	28.38	104.93	4.1	1.43000	0.13800	2.41
76	2012-07-26	28.38	104.83	3.0	0.08700	0.00109	0.41
77	2012-07-28	28.42	104.83	4.0	0.74800	0.04720	1.78
78	2012-07-29	28.38	104.83	3.4	0.21400	0.00559	0.78
79	2012-07-31	28.38	104.85	3.5	0.25900	0.00460	0.52
80	2012-07-31	28.40	104.83	3.1	0.08510	0.00063	0.22
81	2012-08-07	28.42	104.83	3.3	0.12000	0.00199	0.50
82	2012-08-13	28.38	104.83	3.3	0.15100	0.00307	0.61
83	2012-10-19	28.35	104.88	3.2	0.13700	0.00230	0.45
84	2013-02-12	28.32	104.87	3.1	0.14800	0.00226	0.32
85	2013-02-19	28.30	104.90	4.5	5.76000	2.54000	10.81
86	2013-02-27	28.33	104.88	3.1	0.13000	0.00165	0.28
87	2013-04-25	28.40	104.90	5.2	13.50000	7.21000	16.14
88	2013-04-25	28.40	104.90	4.7	6.43000	1.47000	6.29
89	2013-04-25	28.40	104.80	3.7	0.51400	0.03350	1.63
90	2013-05-07	28.35	104.87	4.0	1.04000	0.08780	2.64
91	2013-07-17	28.33	104.88	3.7	0.49300	0.02150	1.24
92	2013-10-09	28.38	104.90	3.4	0.28500	0.00588	0.53
93	2013-10-09	28.37	104.90	3.3	0.29200	0.00898	0.74
94	2013-11-26	28.37	104.90	3.1	0.14300	0.00151	0.32
95	2014-01-14	28.33	104.93	3.6	0.43000	0.01560	0.96
96	2014-05-08	28.33	104.92	3.3	0.17000	0.00356	0.64
97	2014-05-20	28.37	104.92	3.2	0.19500	0.00263	0.38
98	2014-07-18	28.42	104.87	3.3	0.18100	0.00341	0.48
99	2014-07-20	28.42	104.87	3.0	0.10300	0.00136	0.37
100	2014-08-24	28.40	104.87	3.3	0.17200	0.00421	0.67
101	2015-01-28	28.38	104.88	3.2	0.15800	0.00190	0.33
102	2015-01-28	28.37	104.95	3.9	0.98500	0.04980	1.35
103	2015-02-07	28.37	104.90	4.8	9.06000	4.23000	12.60
104	2015-02-07	28.37	104.90	3.8	0.79100	0.03910	1.38
105	2015-02-08	28.37	104.87	3.6	0.36100	0.00825	0.67
106	2015-03-25	28.42	104.82	3.6	0.26600	0.00902	0.94
107	2015-06-26	28.42	104.80	3.0	0.07180	0.00094	0.36
108	2015-08-27	28.35	104.88	3.0	0.10100	0.00143	0.41
109	2015-10-13	28.37	104.90	3.0	0.09750	0.00092	0.28
110	2015-11-30	28.37	104.97	4.0	1.15000	0.13200	2.18
111	2016-04-19	28.38	104.93	3.4	0.13617	0.00966	1.13
112	2016-05-06	28.40	104.82	3.4	0.18485	0.01218	1.16
113	2016-05-06	28.32	104.87	3.1	0.09556	0.00280	0.54
114	2016-05-13	28.42	104.82	3.3	0.12755	0.00612	0.83
115	2016-06-08	28.43	104.80	3.7	0.44057	0.02946	1.46
116	2016-09-29	28.37	104.77	3.1	0.16027	0.00140	0.25
117	2017-01-10	28.38	104.87	3.4	0.17383	0.01189	1.18
118	2017-03-24	28.40	104.92	3.0	0.05497	0.00180	0.51
119	2017-09-21	28.37	104.92	3.1	0.07322	0.00044	0.15
120	2017-09-26	28.35	104.92	3.2	0.07415	0.00129	0.34
121	2017-10-07	28.33	104.92	3.0	0.05087	0.00078	0.28
122	2018-05-04	28.39	104.78	3.4	0.11429	0.00655	0.91
123	2018-05-05	28.38	104.78	4.1	0.84966	0.07271	2.07
124	2018-07-20	28.38	104.77	3.0	0.05471	0.00074	0.26
125	2019-01-04	28.37	104.93	3.8	0.60231	0.01994	0.99
126	2019-01-11	28.37	104.93	3.2	0.10925	0.00201	0.55
127	2019-06-25	28.42	104.79	3.5	0.17094	0.00524	0.92
128	2019-06-26	28.39	104.81	3.9	0.44749	0.02130	1.43
129	2019-06-27	28.43	104.80	3.9	0.44841	0.03550	2.38
130	2019-06-27	28.40	104.80	3.5	0.19787	0.00692	1.05
131	2019-06-29	28.43	104.76	3.9	0.42287	0.02785	1.98
132	2019-06-30	28.43	104.77	3.5	0.18370	0.00450	0.73
133	2019-06-30	28.44	104.81	3.7	0.24911	0.01514	1.82
134	2019-09-06	28.44	104.80	4.2	1.45710	0.19122	3.94
135	2019-09-12	28.43	104.75	4.2	1.47620	0.11941	2.43
136	2019-10-08	28.42	104.78	3.1	0.05254	0.00064	0.36
137	2019-10-11	28.38	104.88	3.0	0.03282	0.00031	0.28
138	2019-10-11	28.38	104.87	3.2	0.06746	0.00089	0.40
139	2019-10-14	28.38	104.87	3.0	0.03307	0.00020	0.19
140	2019-10-17	28.42	104.78	3.2	0.06183	0.00101	0.49
141	2019-10-19	28.35	104.87	3.1	0.11221	0.00107	0.29
142	2019-10-19	28.43	104.72	3.5	0.11758	0.00440	1.12
143	2019-10-21	28.37	104.93	4.1	1.31820	0.07721	1.76
144	2019-10-27	28.40	104.82	3.1	0.07797	0.00060	0.23
145	2019-11-02	28.43	104.68	3.3	0.16523	0.00155	0.28
146	2019-11-05	28.43	104.82	3.1	0.06625	0.00042	0.19
147	2019-11-07	28.37	104.97	3.8	0.39347	0.01673	1.27
148	2019-11-10	28.45	104.78	3.0	0.04824	0.00029	0.18
149	2019-11-10	28.43	104.73	3.9	0.37509	0.01934	1.55
150	2019-11-14	28.38	104.93	3.6	0.21461	0.00484	0.68
151	2019-11-14	28.38	104.95	3.0	0.02971	0.00014	0.14
152	2019-11-21	28.45	104.77	3.2	0.06371	0.00054	0.25
153	2019-11-27	28.37	104.93	4.3	1.54160	0.12428	2.42
154	2019-12-23	28.43	104.77	3.4	0.11617	0.00193	0.50
155	2019-12-26	28.43	104.82	3.8	0.42082	0.00892	0.64
156	2019-12-29	28.38	104.93	4.1	0.65687	0.02621	1.20

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