Did geothermal power plant trigger Pohang quake?

Construction of a geothermal power plant seen above has been halted after the government said it will investigate whether it played any role in triggering a recent earthquake in Pohang. / Yonhap

Gov’t to investigate correlation between the two

By Jung Min-ho

The government will investigate whether the construction of a geothermal power plant in Pohang played any role in causing the 5.4-magnitude earthquake that hit there earlier this month.

The Ministry of Trade, Industry and Energy said Saturday that it will create a task force to look into whether the construction and test operations of the plant, which involves pumping water into and out of an underground reservoir, triggered the quake.

Given that Korea has few experts in the field, the ministry will ask people from other countries to join the team.

The ministry believes the investigation will take at least a year to finish. In the meantime, the construction project, which was started in 2010, will be suspended.

Korea University geology professor Lee Jin-han is the first scholar who raised the possibility of what is known as “induced seismicity,” which refers to tremors that are caused by human activity that alters the stresses and strains on the Earth’s crust, with regard to the Pohang earthquake.

A hot dry rock enhanced geothermal system project in Switzerland was canceled in 2009 due to similar concerns. The plan aimed to generate power by boiling water beneath the Earth’s surface, but was abandoned following quakes and a risk assessment showing high prospects of more tremors because of drilling.

U.S. experts also believe that a series of quakes in Oklahoma in recent years were caused by an increase in wastewater injection from oil and gas production. Injected into underground wells, they say the fluids can cause pressure changes to faults and make them more likely to move.

Whether the construction and test operations of the geothermal power plant were the cause of the Pohang quake was debated at a forum in the Press Center in Seoul, Friday.

Some scholars, including Pusan National University geologist Kim Kwang-hee, said the plant may not be the chief cause of the quake but it is possible that it played a role.

Kim pointed out that four minor quakes (2.0-magnitude or higher) occurred in the city after builders started to inject wastewater underground last year.

But other scholars, including Yonsei University earth science professor Hong Tae-kyung, said the total amount of water injected into two holes was only 12 thousand cubic meters, which they believe was too little to trigger seismicity.

Yet the two sides agreed that it is too early to say with confidence what caused the quake, saying thorough research needs to be conducted to collect more facts.