12 consecutive earthquakes in Kon Tum |=> Published in Bac Giang newspaper

In less than ten hours on July 7th, 12 earthquakes with aftershocks ranging from 2.5 to 4.2 magnitude occurred in Kon Plông district, according to the Institute of Geophysics.

12 trận động đất liên tiếp, động đất tại Kon Tum, huyện Kon Plông

The epicenter of the 4.2 magnitude earthquake on the morning of July 7th. Source: Earthquake Information and Tsunami Warning Center.

The first earthquake occurred at 9:31 AM, with a magnitude of 3.9 and a depth of approximately 8.1 km. Following this, 11 other earthquakes of varying magnitudes, ranging from 2.5 to 4.2, occurred consecutively. The most recent earthquake was recorded at 7:56 PM with a magnitude of 2.5 and a depth of approximately 8.1 km. The Earthquake Information and Tsunami Warning Center - Institute of Geophysics is currently monitoring these earthquakes.

Dr. Nguyen Xuan Anh, Director of the Institute of Geophysics, believes that the earthquake was triggered by the hydroelectric reservoir impounding water.

In August 2022, 12 earthquakes occurred in two consecutive days. 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 other times when there are only a few occasional ones, closely related to the water storage operation of hydroelectric reservoirs," he said. Compared to a few days earlier, the number of recorded earthquakes was clearly higher, but still within the triggered earthquake series and the weak earthquake zone. Therefore, the maximum earthquake magnitude in the area did not exceed 5.5.

Mr. Xuan Anh stated that monitoring of earthquake activity is still necessary to detect any abnormalities and will notify the public to reassure them. Currently, no casualties have been reported.

Previously, Associate Professor Dr. Nguyen Hong Phuong, a seismologist at the Institute of Geophysics, shared that the cause of induced earthquakes is understood to be due to human impact on nature, rather than natural earthquakes like those in northern regions, which are caused by natural fault zones.

According to Associate Professor Phuong, induced earthquakes follow an easily understandable pattern, mostly occurring in areas with active reservoirs, especially hydroelectric reservoirs or large water storage reservoirs. When a reservoir is filled with water, the large volume of water exerts significant pressure on the reservoir bottom. Combined with local faults (even small ones), this increased stress on the large water column causes induced earthquakes.

The triggered earthquakes typically follow a cycle, occurring after periods of water accumulation and the rainy season. Once they reach a peak, they begin to diminish, forming a series of medium- and moderate earthquakes, before eventually dying off. "The duration of this dying-off will need to be studied, depending on local monitoring stations, as the cycle will vary in different regions," he said.

According to experts, the earthquake in Kon Plông, the site of the Thượng Kon Tum hydroelectric dam construction, shares similarities with the phenomenon at the Sông Tranh 2 hydroelectric dam in Quảng Nam – both are induced earthquakes occurring in reservoir areas. When hydroelectric power plants operate, they increase stress, putting pressure on the ground, leading to landslides that generate earthquakes.

In March 2021, the Thuong Kon Tum hydropower plant began impounding water for electricity generation. From April 2021 onwards, earthquakes occurred repeatedly in Kon Plong and neighboring districts, with the frequency of these earthquakes increasing dramatically thereafter.

Statistics show that over the 117 years from 1903 to 2020, the Kon Plông area recorded only about 33 earthquakes of magnitude 2.5 or higher. However, since 2021, over 200 new earthquakes have occurred there. Experts agree that it is very difficult to accurately predict the timing of earthquakes.

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