GRAPH
Two earthquakes set off an explosion near a hydropower plant prompting terrified residents to flee into the streets.

A 3.9 magnitude earthquake rocked the notorious Song Tranh Hydropower reservoir at 11:20 a.m. on February 26; local authorities described it as the strongest measured in a year.

Vietnam's Institute of Geophysics says the quake originated roughly 10 km below the ground in Nam Tra My District.

"The quake lasted five seconds, shook many houses and was followed by the shock of explosion," said the District Chairman Ho Quang Buu. "Many people rushed out of their houses in fear."

The Song Tranh 2 Hydropower Plant in Nam Tra My District, Quang Nam Province. The dam is suspected of having caused a series of minor earthquakes several years ago.
© VnExpress/Tri Tin The Song Tranh 2 Hydropower Plant in Nam Tra My District, Quang Nam Province. The dam is suspected of having caused a series of minor earthquakes several years ago.

The second minor earthquake jolted the area at 1:05 p.m. So far no significant damages, injuries or deaths have been reported as a result of the quake.

The area is being extensively monitored by the Earthquake Information and Tsunami Warning Centre at the Institute of Geophysics.

Over the past few years, Quang Nam Province has experienced several earthquakes which seismologists believe were triggered by hydropower reservoirs.

According to scientists, the extra water pressure has created fissures in the ground water under a reservoir. When the pressure of the water increases, it acts to lubricate faults which are already under tectonic strain but are prevented from slipping by the friction of the rock surfaces.

Seismologists said Vietnam's geographic location near fault lines put it at risk from moderate earthquakes.