March 21, 2019 09:37
A 5.4 magnitude earthquake that struck the southeastern port city of Pohang and left some 1,300 people homeless in November 2017 was a man-made disaster, according to a government report.
The report says the tremor occurred due to fault dislocations caused by increasing hydraulic pressure after a nearby geothermal power plant injected up to 900 tons of water into the ground every day.
It was the second-largest quake to hit the Korean Peninsula since measurements began in 1978 and caused chaos when the nationwide college entrance exam scheduled the next day was postponed for a week to make sure candidates were safe.
After a yearlong investigation, a government team led by the Geological Society of Korea released the report on Wednesday. "A series of micro quakes occurred after water was injected into the ground, which triggered the massive quake later on," Prof. Lee Kang-keun of Seoul National University, who led the team, told reporters. "The Pohang quake wasn't a natural disaster."
The investigation began in March last year, and several foreign seismologists also took part.
For geothermal power generation, two holes are drilled more than 4 km into the ground. Water is injected into one hole, warmed by subterranean heat, and steam extracted out of the other to power a turbine that generates electricity.
Some geologists such as Prof. Ree Jin-han of Korea University had pointed the finger at the geothermal power plant immediately after the quake, given that the epicenter was a mere 600 m away. The investigators provided evidence that micro quakes were concentrated along the specific fault line where the massive tremor occurred.
Similar data had been compiled and reported by the geothermal power plant itself to the government, which nonetheless allowed it to keep operating. As a result the government could have to pay out trillions of won in damages (US$1=W1,130). The power plant started as a public-private project with W18.5 billion in taxpayers' money.
A Pohang civic group has already pledged to sue the government. Lawyers speculated that damages could rise to W5 trillion if all citizens of Pohang take part in the lawsuit.
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