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A magnitude 4.9 earthquake occurred in Xiaogan on the 26th. It was not in the seismic zone. Why did the earthquake occur?
Release time:
2019-12-27 10:02
Source:
Hubei Province is far away from the earthquake zone. In many people's hearts, they always feel that the earthquake is far away from us. However, the earthquake still let us all feel it. The land under our feet does not seem to be as safe and calm as imagined.
95% of the world's earthquakes are concentrated in modern plate activity contact zones, such as the Pacific Rim seismic zone (Chile, Taiwan and Tangshan earthquakes belong to this range), and the Himalayan-Mediterranean seismic zone (such as Wenchuan). Hubei Province is lucky enough to avoid these major seismic zones. China has also designated dozens of inland seismic zones (areas), and Hubei Province is not on these seismic zones (areas).
Since the history of earthquake records, there have been 33 earthquakes between magnitude 4.7 and magnitude 6.5 in Hubei, and this Yingcheng earthquake is the 34th. The three larger ones were the Zhushan earthquake of magnitude 6.5 in 788, the Xianfeng earthquake of magnitude 6.25 in 856, and the Macheng earthquake of magnitude 6 in 1932. The epicenter intensity was as high as 8 degrees, causing landslides, collapse of buildings, and heavy casualties of humans and animals. After the founding of New China, there was no major earthquake in Hubei Province.
Hubei Province is not in the seismic zone, what will happen to the earthquake?
The crustal movement is not balanced, and its occurrence is related to the tectonic unit. Geotectonic units are generally defined by uplift and depression; they can also be divided into active and stable zones according to the intensity of crustal movement.
Most of the active areas are at the transition between the uplift area and the depression area, where the differential rise and fall of the crust will cause the strata to be faulted (I. e., faulted) or re-active the original fault, which is often referred to as active fault. The strongest manifestation of active faults is earthquakes. Therefore, it can be said that the earthquake is the result of the fault activity, or it can be said that the fault is active because of the earthquake.
Therefore, even if Hubei Province is not in the earthquake zone, but the new tectonic movement of crustal subsidence will also lead to earthquakes.
At the same time, because water storage and mining change the original stress balance state, it will also lead to earthquakes, but such earthquakes are generally small in magnitude and shallow in source, and generally do not cause major damage.
Xiaogan earthquake
