South Korea accepts a geothermal plant likely to cause a destructive earthquake

A panel of the South Korean government concluded that an earthquake of magnitude 5.4 that struck Pohang City on November 15, 2017 was probably due to an experimental geothermal power plant. The panel was convened by order of the President and published its conclusions on March 20th.

Unlike conventional geothermal power plants, which directly extract energy from groundwater or hot rocks, the Pohang NPP injected a fluid under high pressure into the ground to fracture the rock and generate heat, a technology known as the name of improved geothermal system. This pressure caused small earthquakes that affected nearby faults and finally triggered the earthquake of 2017, the panel said.

The earthquake was the second most violent and destructive ever in the country, injuring 135 people and causing about 300 billion won (290 million US dollars). The country's Ministry of Commerce, Industry and Energy, which financed the plant, said in a statement that it accepted the group's findings and "expresses its deep regret" to the citizens of Pohang, who were hurt by the event.

The ministry announced that it would dismantle the plant, restore the site to its original state and invest 225.7 billion won to repair the infrastructure in the most affected area. The results corroborate the findings of a pair of studies published in Science^1,2 last year, which suggested the plant as the probable cause of the earthquake.

Earthquakes have been linked to geothermal power plants in other parts of the world. But the Pohang earthquake is by far the most powerful ever associated with this type of installation – 1,000 times more powerful than a magnitude 3.4 earthquake caused by a plant in Basel, Switzerland, in 2006.