Reservoir-educed quakes at Song Tranh 2 Plant: Expert

Reservoir-educed earthquakes in the Song Tranh 2 Hydropower Plant area are typical as they occur in quick succession and in a non-earthquake zone, said Associate Professor and Dr. Cao Dinh Trieu from the Institute of Geophysics on Thursday.

The Song Tranh 2 Hydropower Plant dam is at 97m altitude and five kilometers from Bac Tra My Town (Photo: SGGP)

He was speaking at a conference hosted by the People’s Committee in the central province of Quang Nam and the Institute of Geophysics, to raise awareness on earthquakes and ways to cope with them.

Dr. Trieu said that reservoir-educed earthquakes have been occurring periodically and in quick succession in Bac Tra My District, which is a non-earthquake belt. Such phenomenon has not occurred in other reservoirs in the world.

Out of the 45,000 water reservoirs in the world, 150 have seen reservoir-educed earthquakes and only one percent have faced   incidents.

The strongest reservoir-educed quake in the world was recorded at the Koyna Hydropower Plant in India of intensity 6.3 on the Richter scale.

The higher the reservoir is located, the more frequent the earthquakes, said Dr. Trieu.

Specifically, quake frequency is 6 percent at 90-120m, 17 percent at 120-150m and 25 percent at 150-250m altitude. Song Tranh 2 Hydropower Plant reservoir falls in the first category. 

Dr. Trieu warned that the Song Tranh 2 reservoir must be protected from landslides and flashfloods and water levels should not fluctuate as this may cause earthquakes.

At the conference, Dr. Trieu introduced ten measures to cope with earthquakes in Quang Nam Province.
He said that educed earthquakes are always milder than tectonic earthquakes and occur in hollow layers of the earth, which usually cause loud explosions; similar to ones heard by residents in Bac Tra My District.
The province and the institute will continue to host similar conferences in Bac Tra My District, which continually has had to deal with recurring earthquakes.
Dr. Nguyen Xuan Anh, head of the Institute of Geophysics, said that the first earthquake observation station is expected to be installed near the Song Tranh 2 Hydropower Plant dam and will be fully operational by October 19.

The station will better help estimate future quakes in Bac Tra My District and forecast other oncoming quakes.

The institute will invite experts on educed earthquakes from Russia, Poland and India to study the Song Tranh 2 Hydropower Plant area.

By Nguyen Khoi – Translated by Hai Mien

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