1990 Gonghe earthquake

The 1990 Gonghe earthquake occurred on April 26 at 17:37 China Standard Time in Hainan Tibetan Autonomous Prefecture, Qinghai Province. The mainshock had a surface wave magnitude of 7.0 M_s  and a moment magnitude of 6.5 M_w .^[2] It was presaged by two foreshocks that struck merely seconds before the main earthquake.^[3][4] On the Mercalli intensity scale, the earthquake had a rating of IX (Violent).^[5]

1990 Gonghe earthquake

Show map of Qinghai Show map of China
UTC time	1990-04-26 09:37:15
ISC event	373782
	373783
USGS-ANSS	ComCat
Local date	26 April 1990 (1990-04-26)
Local time	17:37 CST
Magnitude	7.0 Ms
Depth	8.1 km
Epicenter	35.986°N 100.245°E / 35.986; 100.245
Type	Reverse
Areas affected	China
Max. intensity	MMI IX (Violent)
Casualties	126 dead[1]

Damage

At least 126 people died and 2,049 left wounded by the earthquake.^[1] Landslides and extensive destruction was reported in the area. Damage to properties was major, with 21,000 homes collapsing and another 66,800 damaged. The Longyangxia Reservoir about 60 km away from the earthquake experienced strong shaking which triggered landslides but its nearby power plant and dam were in normal working conditions.^[6] Total damage caused by the earthquake is estimated at 270 million Chinese Yuan.^[7]

In the zone with the highest intensity, IX, encompassing Gonghe County, all brick and adobe constructed houses were razed. About 320 wood-framed and mud-walled settlements were destroyed, the only 12 left standing suffered serious damage. Brick and concrete bungalows did not collapse but they were severely compromised after the earthquake. In zones with intensities VII and VIII, more homes collapsed, causing casualties. Some old houses in zone VI also collapsed.^[5]

Characteristics

The earthquake in the northeastern Tibetan Plateau according to seismologists, ruptured a blind thrust fault structure due to the absence of a surface rupture.^[8] Elements of both sinistral strike-slip and reverse components were detected during the co-seismic rupture, with the latter having a greater sense.^[9] The estimated length and width of the rupture is 37 km and 6 km respectively, with a slip of around 2.7 meters.^[10]

See also

• List of earthquakes in 1990
• List of earthquakes in China

References

1. "CHINA: QINGHAI PROVINCE: GANGHE-XINGHAI". NGDC NCEI. NCEI. Retrieved 19 March 2021.
2. "M 6.5 - southern Qinghai, China". USGS-ANSS. USGS. Retrieved 19 March 2021.
3. "M 6.3 - northern Qinghai, China". USGS-ANSS. USGS. Retrieved 19 March 2021.
4. "M 6.2 - northern Qinghai, China". USGS-ANSS. USGS. Retrieved 19 March 2021.
5. Wenjing, Ma; Yaling, Zhang; Wenwei, Zou. "The Gonghe magnitude 7.0 earthquake in Qinghai Province on April 26, 1990". data.earthquake.cn (in Chinese). Seismological Bureau of Qinghai Province. Retrieved 19 March 2021.
6. "青海共和地震". Chinese Academy of Sciences (in Chinese). Retrieved 19 March 2021.
7. "新闻背景：1976年以来中国发生的六级以上大地震". gov.cn (in Chinese). Central People's Government of the People's Republic of China. Retrieved 19 March 2021.
8. Hao, Ming; Shen, Zheng-Kang; Wang, Qingliang; Cui, Duxin (2012). "Postseismic deformation mechanisms of the 1990 Mw 6.4 Gonghe, China earthquake constrained using leveling measurements". Tectonophysics. 532–535: 205–214. Bibcode:2012Tectp.532..205H. doi:10.1016/j.tecto.2012.02.005. ISSN 0040-1951. Retrieved 19 March 2021.
9. Chen, Y.T.; Xu, L.S.; Li, X. (1996). "Source process of the 1990 Gonghe, China, earthquake and tectonic stress field in the northeastern Qinghai-Xizang (Tibetan) plateau". Pure and Applied Geophysics. 146 (3–4): 697–715. Bibcode:1996PApGe.146..697C. doi:10.1007/BF00874741. S2CID 129267313. Retrieved 19 March 2021.
10. Wang, W.P.; Wang, Q.L. (1999). "Dislocation parameters of Gonghe earthquake jointly inferred by using genetic algorithms and least squares method". Acta Seismologica Sinica. 12 (3): 314–320. Bibcode:1999AcSSn..12..314W. doi:10.1007/s11589-999-0041-2. S2CID 129290131. Retrieved 19 March 2021.