2019 Zigong earthquake
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 Intensity map produced by the U.S. Geological Survey based on felt reports collected from the online Internet Feeling Survey. | |
  | |
| UTC time | 2019-02-25 05:15:59 |
|---|---|
| USGS-ANSS | ComCat |
| Local date | 25 February 2019 |
| Local time | 13:15:59 |
| Magnitude | Ms 4.9 (CENC) mb 4.9 (USGS) |
| Depth | 5 km (3.1 mi) |
| Epicenter |  China, Sichuan Province, Zigong City, Rong County29°29′N 104°29′E / 29.48°N 104.49°E |
| Total damage | 2 dead 12 injured |
| Max. intensity | CSIS VI |
The 2019 Zigong earthquake (also known as the Rongxian earthquake) occurred in Zigong, Sichuan Province, China, at about 13:15 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]
Foreshocks
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]
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
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
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]