A magnitude 3.6 earthquake occurred in Beichuan County, Mianyang City. Why do earthquakes happen one after another?

A magnitude 3.6 earthquake occurred in Beichuan County, Mianyang City. The reason for the successive earthquakes in this area is mainly because it is located at the intersection of Huya fault and Wenchuan-Maoxian fault, and the geological movement is very active.

According to the official measurement by China Seismological Network, just in the early morning of 1 October 23rd, two earthquakes of magnitude 3.0 and1earthquake of magnitude 2.8 occurred in Beichuan County, Mianyang City, Sichuan Province. At noon on the 23rd, the reporter learned from the Earthquake Administration of Sichuan Province that after comprehensive analysis by experts, it was considered that the three earthquakes that occurred this morning and the Mianyang Beichuan earthquake with Ms 4.6 and Ms 4.7 were the aftershocks of the Wenchuan earthquake, which were normal aftershock sequence attenuation activities. The Sichuan Earthquake Administration will closely follow the development of aftershocks and strengthen analysis and judgment.

So, are these two earthquakes aftershocks of the Wenchuan earthquake?

In fact, according to the analysis of experts from Sichuan Earthquake Administration, the linear distance between these two earthquakes is only 1km, and they are both located at the intersection of Huya fault and Wenchuan-Maoxian fault. Since 438+00, there have been seven groups of earthquakes of magnitude 4.5 or above in Wenchuan aftershock area. Combined with regional structure, geophysical observation and aftershock sequence, it is considered that the Beichuan M 4.7 earthquake still belongs to Wenchuan aftershock area. It is worth mentioning that there are 30 seismic stations within 50 kilometers near the epicenters of these two earthquakes, and there are 129 seismic stations within 100 kilometers. The average distance between stations is10km, and the monitoring ability reaches 1.0, which is very good for monitoring aftershocks. Moreover, the Earthquake Administration of Sichuan Province has been continuously monitoring, tracking, analyzing and judging the earthquake situation in this area.

It is worth mentioning that the Wenchuan earthquake-stricken area belongs to the post-earthquake recovery and reconstruction area, and the seismic fortification intensity of buildings is Vlll(8) degrees. The maximum intensity of this earthquake is VI (6) degrees, which is lower than the fortification intensity, so these earthquakes have not caused serious damage to buildings. Not only that, just six seconds after the earthquake, the Sichuan Earthquake Administration released the earthquake warning information, and released the warning information to the public in Chengdu, Mianyang and peace county through the early warning terminal, mobile APP and radio and television. According to preliminary statistics, about 4342 users have received early warning information.

Just after the earthquake of magnitude 4.6 occurred in Beichuan, Mianyang, Sichuan at noon on June 5438+1October 2/KLOC-0, many netizens said at that time that the earthquake should be related to the rising temperature of Mianyang well water. However, the Seismological Bureau of Sichuan Province said that the Beichuan M 4.6 earthquake was about 8 1 km away from the well, and the occurrence of this earthquake had nothing to do with the temperature rise of the well. Experts from the Sichuan Earthquake Administration said that the Beichuan M 4.6 earthquake at noon that day was a normal ups and downs activity in the Wenchuan aftershock area, that is to say, the two earthquakes were actually aftershocks of the Wenchuan earthquake.

In fact, since the beginning of this year, there have been 78 earthquakes of magnitude 3 or above in Sichuan Province, including 66 earthquakes of magnitude 3.0 to 3.9, 0 earthquakes of magnitude 4.0 to 4.9/kloc-0, 2 earthquakes of magnitude 5.0 to 5.9 and 0 earthquakes of magnitude 6.0 or above. On April 65, 438+0, the largest earthquake occurred in shiqu county, Ganzi Prefecture. It can be seen from here that earthquakes in Sichuan Province are quite frequent, mainly because it is at the junction of two plates.