VietNamNet Bridge - Scientists from the Geophysics Institute, an arm of the Vietnam Science & Technology Academy, have reassured the public that the recent earthquakes in Bac Tra My district of Quang Nam province were ‘anticipated’.

Song Tranh 2 hydropower plant.

Four earthquakes have occurred this year in the same district of Bac Tra My district of the central province of Quang Nam. However, it was 2012 which witnessed the highest number of earthquakes, including one measured at 4.7 on the Richter scale.

Scientists noted that earthquakeshave been occurring since 2012, but the number of strong ones measured at 3.0 or higher on the Richter scale is on the decrease. Most of them were small, less than 2.0 on Richter scale.

According to Dr Nguyen Xuan Anh, head of the Geophysics Institute, 13 earthquakes occurred in 2015 alone. All of them were weaker than the strongest earthquake predicted to occur in Bac Tra My, at 5.5 on the Richter scale.

Most recently, two earthquakes occurred in April.

Anh affirmed that the earthquakes in the area were all reservoir-induced earthquakes, which means the earthquake occurred as a result of excitation from hydropower water reservoirs.

Anh explained that though it is now the dry season, the Song Tranh 2 Hydropower Plant’s water reservoir still has high water levels and are not depleted as feared.

He said the water level there is at 172meters while the maximum height is 175 meters.

In principle, the volume of water stored in reservoirs is proportional to earthquake activities. If the water level rises, there could be more earthquakes and vice versa.

Nguyen Hong Phuong, deputy director of the Earthquake and Tsunami Information Center, said they were not relatedto recent earthquakes in Japan and Ecuador, and the ones in Bac Tra My.

“The principles of the earthquakes are quite different. The earthquakes in Bac Tra My were reservoir induced ones. Meanwhile, the earthquakes in Japan and Ecuador were caused by activities of the fault zone,” Phuong said on VTV.

According to Anh, the Geophysics Institute is carrying out a scientific research work on earthquakes which is expected to end in late April. By that time, scientists will give assessments about the earthquakes in Bac Tra My.

He said that the earthquake monitoring in Bac Tra My area is still maintained, and his institute will cooperate with local authorities and suggest suitable solutions to ensure safety for local people.

Thanh Mai