Within a few hours on the morning of September 22, in Kon Plong district, there were 7 earthquakes causing aftershocks ranging from 2.7 to 4.4 magnitude, but no damage was caused, according to the Institute of Geophysics.
A 4.4 magnitude earthquake occurred in Kon Plong district, Kon Tum province at 7:45 a.m. at a depth of about 8 km. People in neighboring areas such as Kon Ray district and Kon Tum city (Kon Tum province) also felt the tremors. At around 8:00 a.m. to 8:30 a.m., two more earthquakes occurred at a depth of 10 km, with aftershocks ranging from 2.7 to 2.8 magnitude. The most recent earthquake occurred at 10:25 a.m. with a magnitude of 3.6. The magnitude of these earthquakes does not pose a risk of natural disasters. The Earthquake Information and Tsunami Warning Center, Institute of Geophysics, continues to monitor these earthquakes.
The epicenter of the 3.6 magnitude earthquake on the morning of September 22. Source: Earthquake Information and Tsunami Warning Center
Dr. Nguyen Xuan Anh, Director of the Institute of Geophysics, stated that Kon Tum is located in the stimulated earthquake chain and in the weak earthquake range. Therefore, the maximum earthquake in the area does not exceed 5.5 degrees. Through observation, the cause of the above phenomenon is related to the stimulated earthquake caused by the reservoir.
In July this year, in less than ten hours on July 7, Kon Plong district experienced 12 earthquakes causing aftershocks ranging from 2.5 to 4.2 magnitude. According to Dr. Xuan Anh, this recurring phenomenon shows that "triggered earthquakes also occur in cycles. There are times when earthquakes occur in a series, and there are times when there are only a few, closely related to the process of water storage operations of hydroelectric reservoirs," he said.
Previously, Associate Professor Dr. Nguyen Hong Phuong, a seismologist at the Institute of Geophysics, shared with VnExpress that the cause of the induced earthquake was understood to be due to human impact on nature, not natural earthquakes like in the northern regions, due to natural fault zones.
According to Associate Professor Phuong, induced earthquakes have an easy-to-understand rule, mostly occurring in areas with active reservoirs, especially hydroelectric reservoirs or large water reservoirs. When a reservoir is filled with water, the amount of water causes great pressure on the bottom of the reservoir, combined with local faults (even small ones), increasing the stress of the large water column will cause induced earthquakes.
The induced earthquakes are usually cyclical, occurring after the water accumulation period and the rainy season. Once they reach a certain peak, they will gradually decrease, forming a series of medium and small earthquakes, then gradually die out. "How long the die out will need to be studied, depending on the local monitoring stations, because in different regions the cycle will be different," he said.
Mr. Xuan Anh said that it is still necessary to continue monitoring earthquake activities to detect any abnormalities and notify people to feel secure. He also noted that earthquake hazard assessment is necessary and needs to be updated annually to serve the work of planning socio-economic development and earthquake-resistant design for all types of works from key to residential areas.
Statistics show that in 117 years, from 1903 to 2020, the Kon Plong area recorded only about 33 earthquakes, from 2.5 magnitude and above. However, from 2021 to now, there have been over 200 new earthquakes. Experts all say that it is very difficult to predict exactly when an earthquake will occur.
Nhu Quynh
Source link
Comment (0)