Nguyen Xuan Anh, head of the Institute of Geophysics, on Tuesday said the number of earthquakes in Kon Plong District and nearby areas has been increasing since April 2021.
Last year, there were 169 earthquakes of a Richter magnitude of 2.5 in the region. Between April 15 and 18 this year, there were already 22 earthquakes, with the biggest having a magnitude of 4.5, said Anh.
"These are alarming numbers because for the previous 120 years, the Kon Plong region only recorded 33 earthquakes, of which two had a magnitude greater than 3," he added.
Besides geological faults, earthquakes might also be caused by water storage at dams, which may explain earthquakes in the Tranh River hydropower plant region of Quang Nam Province (429 km north of Dak Lak), said Anh. In future, there might be more earthquakes in Kon Plong, with magnitudes of up to 5.5 or even higher, he warned.
The Institute of Geophysics is proposing to build two more stations for better surveillance and to figure out the cause of the earthquakes.
Tran Quang Hoai, head of Vietnam Disaster Management Authority, said the heightened frequency of earthquakes might be caused by hydropower dams. Recently, there was no major construction in the Kon Tum region, except for hydropower activities.
Hoai therefore proposed the Upper Kon Tum hydropower plant to stop storing water during unseasonal rain as it may trigger more earthquakes. The geophysics institute also needs to communicate information about earthquakes to authorities more quickly for early response, he added.
Kon Tum authorities need to cooperate with hydropower plants and owners of sensitive infrastructure to prepare contingency plans for different situations.
Pham Trong Thuc, deputy head of the Industrial Safety Techniques and Environment Agency, said that while he does not dismiss that the earthquakes were triggered by water storage activities, authorities also need to look at other causes as possible explanations.
"The water stored at the hydropower reservoir isn't too much; it has only reached 73 percent of the reservoir's maximum capacity. Technically, the plant still has it under control," said Thuc.
At nearly 1 p.m. on Monday, an earthquake with a magnitude of 4.5 hit Kon Plong District, and several neighboring regions. It was the fourth earthquake recorded within the day; the previous three were recorded at 6:13, 6:22 and 11:57 a.m.