Seismic potential in the southeastern margin of Bayanhar block after 2017 Jiuzhaigou earthquake, China – insight from stress evolution and earthquake probability estimation

Figures & data

Figure 1. Regional geologic tectonics, major active faults configuration and strong earthquakes distribution, in which, BHB: BayanHar block; LMSF: Longmenshan fault; MJF: MinJiang fault; XSHF: XianShuiHe fault; LRBF: LongRiBa fault; ANHF: AnNingHe fault; HYF: HuYa fault; QCF: Qingchuan faultEKLF: Eastern KunLun fault; WQLF: Western qinling fault.

Figure 2. The constructed 3D Finite element model.

Figure 3. The elevation (a), Moho depth (b), Possion ratio at 0 and 20 km (c,d) and young’s modulus at 0 and 20 km (e,f) of model.

Table 1. Viscosity coefficient of this model.

Layer	Sichuan Basin	West of LMSF	Depth
1	1.0 × 10^23Pa.s	1.0 × 10^23Pa.s	0-20 km
2	1.0 × 10^22Pa.s	5.0 × 10^20Pa.s	20-Moho
3	1.0 × 10^20Pa.s	1.0 × 10^20Pa.s	Moho-80 km
4	1.0 × 10^20Pa.s	1.0 × 10^20Pa.s	80-120 km

Figure 4. (a) The comparison between the simulated result and observation of GPS, (b) The comparison between the simulation result and observation of the maximum principal compressive stress direction from World stress map 2008.

Table 2. The parameters of these strong earthquakes since 1893 in research region.

Number	Event Time	Epicenter			Magnitude/ Ms	Rupture length /km	Horizontal dislocation /m	Focal mechanism
		Location	Longitude/°	Latitude/°				Strike/°	dip/°	rake/°
1	1893.08.29	Bamei	101.5	30.6	7	70	2.44	322	85	13
2	1904.08.30	Daofu	101.1	31.0	7	50	0.78	322	85	13
3	1923.03.24	Luhuo	100.75	31.3	7.3	60	3	306	90	0
4	1933.08.25	Diexi	103.4	31.9	7.5	85	0.72	14	60	−168
5	1955.04.14	Kangding	101.8	30.0	7.5	85	0.72	160	90	0
6	1973.02.06	Luhuo	100.5	31.5	7.6	90	4	125	87	0
7	1976.8.16	Songpan	104.1	32.7	7.2	45	1.10	165	63	40
8	1976.08.23	Songpan	104.3	32.5	7.2	22	1.1	165	65	40
9	1981.01.23	Daofu	101.1	31	6.9	44	0.5	85	13	44
10	2008.05.12	Wenchuan	103.4	31.0	8.0	>300	2.4	231	35	138
11	2013.04.20	Lushan	102.89	30.3	7.0	46.7	1.3	212	44	92
12	2017.08.08	Jiuzhaigou	103.82	33.2	7.0	30	0.47	150	78	−13

Data description: The data for the Diexi earthquake is from Kan et al. (1977); The data for the Kangding earthquake is from Molnar and Qidong (1984), Kan et al. (1977); The data for the Songpan earthquake is from Yue et al. (2008); The data of Wenchuan earthquake is from CENC, Global CMT, Xu et al. (2008); The data of Lushan earthquake is from Xu et al. (2013). Zhang et al. (2013). The data of the Jiuzhaigou earthquake is from Cheng et al. (2018). The data on Daofu and Luhuo earthquakes are from Cheng (2014). For the earthquake without an explicit data source, the rupture lengths, and horizontal misalignment data are given using the statistical relationship of Wells and Coppersmith (1994).

Figure 5. The annual Coulomb stress change at 20 km depth.

Figure 6. Coseismic Coulomb stress changes of strong earthquakes since 1893 in the research area.

Figure 7. Stress evolution of the main faults in the study area since 1893.

Figure 8. The spatial distribution of historical earthquake with magnitude over 3 (a) and spatial distribution of probability of strong earthquakes with Magnitude 6 (b) in the next 10 years in the study region.

Table 3. Earthquake probability of major faults in study region after Wenchuan earthquake.

Number	Fault	Maximum probability of strong earthquake with magnitude 6 in 10 years after Wenchuan earthquake	Maximum probability of strong earthquake with magnitude 6 in 30 years after Wenchuan earthquake	Maximum probability of strong earthquake with magnitude 7 in 30 years after Wenchuan earthquake
F1	HYF	12.99%	18.6%	2.04%
F2	Northern segment of LMSF	12.85%	18.24%	1.99%
F3	Middle segment of LMSF	15.29%	21.58%	2.4%
F4	Southern segment of LMSF	13.99%	19.85%	2.19%
F5	LRBF	4.5%	6.69%	0.69%
F6	MJF	3.68%	5.26%	0.56%
F7	XSHF	13.51%	19.13%	2.1%

Figure 9. The spatial distribution of probability of strong earthquakes with Magnitude 6(a) and magnitude 7 (b) in the next 30 years in the study region.

Figure 10. The spatial distribution of probability of strong earthquakes with Magnitude 6 in the study region in the next 10 years.

Table 4. Earthquake probability of major faults in study region after Jiuzhaigou earthquake.

Number	Fault	Maximum probability of strong earthquake with magnitude 6 in 10 years after Jiuzhaigou earthquake (ta =10a)	Maximum probability of strong earthquake with magnitude 6 in 10 years after Jiuzhaigou earthquake (ta =85a)
F1	HYF	11.58%	30.78%
F2	Northern segment of LMSF	12.94%	30.37%
F3	Middle segment of LMSF	14.48%	33.92%
F4	Southern segment of LMSF	13.45%	32.10%
F5	LRBF	4.99%	9.31%
F6	MJF	5.0%	10.27%
F7	XSHF	17.42%	34.48%

Figure 11. The spatial distribution of probability of strong earthquakes and two strong earthquakes with Magnitude over 6 in the study region in 2022.

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Code availability

The code is available from the corresponding author on reasonable request.

Data availability

The terrain elevation data of ETOPO1, which are released by the U.S. National Geophysical Data Center (http://www.ngdc.noaa.gov/mgg/global/global.html). The observed and inversed stress data which have been used to compare with our simulated stress are obtained from World Stress Map (http://www.world-stress-map.org/data/). The GPS data, Moho Depth, Poisson ratio data are obtained from authors of references which have described detailly in the manuscript. The datasets generated during and/or analyzed in this study are available from the corresponding author on reasonable request.