Expert: Batu Niah tremor may be linked to Bakun dam

Hilary Chiew, The Star 3 Feb 10;

THERE could be more minor earthquakes like the one in Batu Niah on Monday with the construction of more dams in the Rejang river basin.

Mild tremors were felt in Batu Niah and Suai following a moderate earthquake in Batu Niah.

The Meteorological Services Department said the quake in the morning measured 3.2 on the Richter Scale.

University Malaysia Sabah Natural Disaster Research Unit head Dr Felix Tongkul said that dam development had long been associated with disturbances to the geological structure beyond the dam sites.

“The proposed construction of more dams in the Bintulu interior is of concern. We suspect the Batu Niah tremor could be linked to the Bakun dam where several fault lines pass.

“The pending impoundment of the dam will create an unnatural load in the area and further destabilise the weak zones,” he said.

Tongkul said that more seismic activities could be expected and the situation would be closely monitored.

Geological studies had been carried out prior to the construction of the 2,400MW hydro-electric dam, he added.

Leading seismologist Harsh K. Gupta, in a 2002 article on Reservoir-Induced Seismicity (RIS) published in Earth-Science Review noted that there are over 90 identified sites of earthquakes triggered by impoundment of reservoirs globally.

Following the tragic Sichuan quake in May 2008, scientists in China and the United States linked the incident to the weight of the Zipingpu dam on which impoundment began in 2004.

The International Commission on Large Dams recommends that RIS should be considered for reservoirs deeper than 100m. Bakun’s reservoir is 194m deep.

Gupta concluded that the depth and volume of a reservoir played a significant role in triggering earthquakes and that seismic activities could happen immediately after the filling of water begins or after a time lag.

The controversial RM7bil dam which displaced 15,000 indigenous people was scheduled for impoundment last November but this was deferred pending approval from authorities.

The Sarawak government has announced the construction of another 12 dams in the state and half of them will be located in the Rejang basin.

Work on the 900MW Murum dam on one of the Rejang’s tributaries began in 2008.

The other five are Belaga (260MW), Lanau (290MW), Baleh (1,400MW), Belepeh (110MW) and Mentjawa (300MW).

The RM3bil Murum dam located 470km inland from Miri will flood about 30,000ha of the Murum Valley and displace 2,800 inhabitants from eight settlements.

Some villagers are resisting relocation as they fear the same fate as those resettled in Sungai Asap as a result of the Bakun dam.