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2019 Zigong earthquake

Coordinates: 29°29′N 104°29′E / 29.48°N 104.49°E / 29.48; 104.49
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2019 Zigong earthquake
Intensity map produced by the U.S. Geological Survey based on felt reports collected from the online Internet Feeling Survey.
2019 Zigong earthquake is located in Sichuan
2019 Zigong earthquake
UTC time2019-02-25 13:15:59
USGS-ANSSComCat
MagnitudeMs 4.9 (CENC)
mb 4.9 (USGS)
Depth5 km (3.1 mi)
Epicenter China, Sichuan Province, Zigong City, Rong County
29°29′N 104°29′E / 29.48°N 104.49°E / 29.48; 104.49
Total damage2 dead
12 injured
Max. intensityCSIS VI

The 2019 Zigong earthquake (also known as the Rongxian earthquake) occurred in Zigong, Sichuan Province, China, at about 13:00 on February 25, 2019.[1] The epicentre was located in Rongxian County (29.48 degrees north latitude, 104.49 degrees east longitude), with a magnitude of Ms 4.9, a focal depth of about 5 km and a maximum intensity of VI.[2][3] The earthquake killed two people and injured 12 others (3 of them seriously).[4]

Seismic background

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Rong County belongs to the moderate seismic activity area in Sichuan. According to the China Earthquake Administration, there are nine smaller-scale ruptures within 100 km of the epicentre. Since the Sichuan earthquake network began observing earthquakes in 1970, five earthquakes of magnitude 4.0 or greater within 50 km of the epicentre have occurred. The largest earthquake of magnitude was a 4.8 magnitude earthquake that occurred on March 29, 1985. Since the Sichuan region was in a relatively active period of seismic activity at the time of this earthquake's occurrence, Rong County has also experienced continued active small earthquakes in recent years.[5]

Du Fang, director of the Sichuan Earthquake Forecasting Research Center, said Earthquakes in Sichuan province have the characteristics of being strong in the west and weak in the east. Judging from historical records and actual structures, there is no tectonic basis for a strong earthquake of magnitude 6 or greater in Rong County.[3]

Foreshocks

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On February 24, 2019, at 05:38—32 hours before the main shock——an earthquake with a magnitude of Ms 4.7 occurred in Rongxian, Zigong City, Sichuan Province, at a depth of about 5 km.[6][7] According to the investigation of Zigong City Earthquake and Disaster Prevention and Mitigation Bureau at that time, the earthquake was strongly felt in Rong County. There were isolated cases of cracking of houses in Gaoshan town, but no casualties were caused.[8] 27 hours later, about 5 hours before the main shock, another earthquake with a magnitude of Ms 4.3 occurred in the area, at a depth of 5 km also.[9]

Earthquake

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According to the China Seismological Network, the epicentre of the earthquake was located in Rong County, Zigong City, Sichuan Province, China (29.48°N, 104.49°E), with a magnitude of Ms 4.9, a depth of about 5 km, and a maximum intensity of VI degrees.[2][3] The U.S. Geological Survey and the European Mediterranean Seismological Center (EMEC) determined the same numerical magnitude as that of China, both at mb 4.9, while both measured a source depth of about 10 km.[10][11] The lower magnitudes measured by the GEOFON standard station network of the German Research Centre for Geosciences, for MB 4.8 level.[12] In addition, based on seismic reports collected by the online Internet seismic survey, the USGS, the maximum intensity of this earthquake was presumed to be VI on February 24, 2019. And after 2 days, the agency revised the intensity presumed by this method to IV.[13]

Earthquake Damage

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The epicentre of the earthquake was only 8 km from the county seat of Rongxian, 32 km of downtown Zigong and 136 km of downtown Chengdu.[14] In addition to the strong tremor felt in the epicentre area, residents living in Yibin City also reported significant tremors.[15] At the time of the earthquake, two residents of Takayama town were killed and 12 others were injured when they were hit by the balcony railing of a collapsed house while walking in the street. Of these, 3 were seriously injured and the other 9 were slightly injured.[15][16] After investigation, a total of 9 houses collapsed and another 10,911 houses were damaged in this earthquake, which also caused cracks in the roofs of 5 small reservoirs, including Shuidagou Reservoir in Gao Shan Town. It is estimated that this earthquake caused a total direct economic loss of 13.99 million RMB.[4]

Response

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After the earthquake, the Sichuan Province Earthquake Bureau activated a Level III emergency response.[citation needed] At around 14:00 on the same day, a 20-member field team led by Lei Jiancheng, deputy director of the Sichuan Earthquake Bureau, went to the Rongxian disaster area to investigate .[17] On the same day, Huang Ming, Secretary of the Party Group of the Ministry of Emergency Management of the People's Republic of China, and Zheng Guoguang, Director of the China Earthquake Administration, gave instructions on emergency work through the emergency command system.[18][19] At 0:30 a.m., the next morning, a team of experts from the Ministry of Emergency Management, led by Yu Shuming, deputy director of the monitoring and forecasting division of the China Earthquake Administration, arrived at the disaster area in Rong County, and a working meeting was held at the on-site command of the Sichuan Provincial Earthquake Bureau.[20]

During the investigation before the earthquake, Gaoshan Town, Rongxian County, the epicentre of the earthquake, found 7 potential disasters. After the 24-day foreshock, the Sichuan Provincial Department of Natural Resources said that no significant changes were found in any of the seven previously identified Geotechnical hazard sites in Gao Shan town.[21]

Although the magnitude of this earthquake was not large, there were casualties. According to He Yulin, a senior engineer at the Sichuan Earthquake Bureau's Engineering Seismology Research Institute, casualties occurred because some old buildings in the area did not meet the current seismic protection standards after completion and the structure of some buildings would be more vulnerable after three consecutive earthquakes in just two days.[3] According to the Earthquake Parameter Zoning Map of China (Fifth Edition), the epicentre area, including Rong County is located in the VI degree fortification zone, and the maximum intensity of this earthquake is also VI degrees.[22]

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Rong County, together with Yibin Changning County and Neijiang Weiyuan County, formed the "Changning-Rongxian-Weiyuan National Shale Gas Industry Demonstration Zone" in 2016, and in August of the same year, Zigong reached a strategic partnership with Sinopec Southwest Oil and Gas Branch for shale gas exploration, development and utilization.[23] After the earthquake, some Zigong residents believed that the local shale gas extraction project caused the earthquake, and thousands of local Zigong residents, thus launched a protest march and surrounded the local government, with some aggressive protesters clashing with local officials,[24][25][26][27] forcing a division of CNPC to suspend operations.[28]

To help residents eliminate their fear of earthquakes, the Sichuan Earthquake Bureau on-site task force entered the affected counties the day after the earthquake to carry out propaganda activities on earthquake prevention and scientific knowledge.[29] Du Fang, director of the Sichuan Earthquake Prediction Research Center, said, "The overall level of seismic activity in the area of Rongxian County, Zigong, where three consecutive earthquakes of magnitude 4 or higher occurred, is low. According to current research, the earthquakes that occurred were all tectonic earthquakes triggered by natural causes. No local tectonic base and gestation conditions exist for destructive earthquakes of magnitude 6 or higher. The main reason for the high interest in earthquakes in this region is related to the high population density in the area. For buildings with adequate fortification standards, earthquakes of magnitude 4 or so generally do not cause major damage."[23]

References

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  1. ^ 四川在线. 自贡荣县发生4.9级地震 系今日第2次4级以上地震. 新浪新闻. 2019-02-25 [2019-02-27]. （原始内容 存档 于2019-09-18）
  2. ^ a b 四川自贡市荣县4.9级地震. 中国地震台网. 2019-02-25 [2019-02-27]. （原始内容 存档 于2019-09-18）
  3. ^ a b c d 马国颖. 四川荣县两天发生3次4级以上地震 专家称属构造性地震. 中国新闻网 四川频道. 2019-02-26 [2019-02-27]. （原始内容 存档 于2019-02-27）
  4. ^ a b 四川自贡荣县2天3次地震 已致2人死亡12人受伤. 中国中央电视台. 2019-02-25 [2019-02-27]. （原始内容 存档 于2019-02-27）
  5. ^ 专家解答：为什么荣县又地震了 ？. 四川省地震局. 2019-02-25 [2019-02-27]. （原始内容存档于2019-02-27）
  6. ^ 四川自贡市荣县4.7级地震. 中国地震台网. 2019-02-24 [2019-02-27]. （原始内容 存档 于2019-09-18）
  7. ^ 四川自贡市荣县发生4.7级地震. 中国中央电视台. 2019-02-24 [2019-02-27]. 原始内容 存档 于2019-02-27）
  8. ^ 四川荣县4.7级地震暂无人员伤亡情况. 四川省地震局. 2019-02-24 [2019-02-27]. （原始内容 存档于2019-09-18）
  9. ^ 四川自贡市荣县4.3级地震. 中国地震台网. 2019-02-25 [2019-02-27]. （原始内容 存档 于2019-09-18）
  10. ^ M 4.9 - 4km SW of Yanling, China. 美国地质调查局. 2019-02-25 [2019-02-27]. （原始内容 存档 于2019-02-27）
  11. ^ M 4.9 - EASTERN SICHUAN, CHINA - 2019-02-25 05:15:59 UTC. 欧洲地中海地震中心. 2019-02-25 [2019-03-06]. （原始内容 存档 于2019-09-18）
  12. ^ Sichuan, China - 2019-02-25 05:16:00.8 UTC. 德国地球科学研究中心. 2019-02-25 [2019-03-06]. （原始内容 存档 于2019-09-18）
  13. ^ M 4.9 - 6km WNW of Yanling, China - Did You Feel It?. 美国地质调查局. 2019-02-26 [2019-03-12]. （原始内容 存档 于2019-09-18）
  14. ^ 四川自贡市荣县发生4.9级地震. 中国地震局. 2019-02-25 [2019-02-27]. （原始内容 存档 于2019-09-18）
  15. ^ a b 四川荣县发生4.9级地震 致2人死亡. 新浪新闻. 2019-02-25 [2019-02-27]. （原始内容 存档 于2019-09-18）
  16. ^ 四川荣县4.9级地震已致2人死亡 地震局组织专家接受采访. 四川新闻网. 2019-02-25 [2019-02-27]. （原始内容 存档于2019-02-27）
  17. ^ 四川省地震局第二批现场工作队出发前往震区. 四川省地震局. 2019-02-25 [2019-02-27]. （原始内容 存档于2019-09-18）
  18. ^ 应急管理部领导对四川荣县4.9地震应急处置作出重要指示. 四川省地震局. 2019-02-25 [2019-02-27]. （原始内容 存档于2019-09-18）
  19. ^ 应急管理部部署四川自贡4.9级地震抗震救灾工作. 新华网. 2019-02-25 [2019-02-27]. （原始内容 存档 于2019-02-27）
  20. ^ 应急管理部专家组抵达荣县. 四川省地震局. 2019-02-26 [2019-02-27]. （原始内容 存档于2019-09-18）
  21. ^ 四川自贡地震震中7处地灾隐患均未发现明确变化. 中国新闻网. 2019-02-24 [2019-03-19]. （原始内容 存档 于2019-02-25）
  22. ^ 四川荣县4.7级地震历史地震数据. 四川省地震局. 2019-02-24 [2019-02-27]. （原始内容 存档于2019-09-18）
  23. ^ a b 澎湃新闻. 地震是否和页岩气开采有关?荣县3个月前曾这样回复. 澎湃新闻网. 上海. [2019-03-25]. （原始内容 存档 于2021-01-03）
  24. ^ Reuters. Mining halts in Sichuan after triple quakes, protests. FMT News. 2019-02-26 [2019-02-27]. （原始内容 存档于2021-04-14）
  25. ^ Shale gas development blamed for quake in China. 日本放送协会. 2019-02-26 [2019-02-27]. （原始内容 存档于2019-02-26）
  26. ^ 「相次ぐ地震はシェールガスのせい」住民抗議で採掘停止 中国. 日本放送协会. 2019-02-26 [2019-02-27]. （原始内容 存档于2019-02-26）
  27. ^ 开采页岩气可引发地震 四川荣县千人围政府. 自由亚洲电台. 2019-02-25 [2019-03-02]. （原始内容 存档 于2019-03-02）
  28. ^ Aibing Guo; Dan Murtaugh. Fatal earthquake shakes China’s shale drilling region. World Oil. 2019-02-26 [2019-02-27]. （原始内容 存档 于2019-02-26）
  29. ^ 四川省地震局现场工作队深入震区开展防震减灾科普宣传. 四川省地震局. 2019-02-26 [2019-02-27]. （原始内容 存档于2019-09-18）
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