SEOUL, October 24 (AJP) - The 2017 Pohang earthquake was a man-made disaster caused by fluid injection at a geothermal power plant, according to Kim Kwang-hee, professor of geological and environmental sciences at Pusan National University.
Speaking at the policy forum "Pohang, Asking Again: Accountability and Prevention of Recurrence" held at the National Assembly Members’ Office Building in Seoul on October 23, Kim said the quake was an induced seismic event, not a natural one. "The Pohang earthquake was an induced event caused by fluid injection at a geothermal power plant," he said.
Kim explained that from 2016 to 2017, tens of thousands of tons of water were injected roughly four kilometers underground. Soon after, the number of small tremors around the plant rose sharply. "The fluid raised pressure along the fault, disturbed stress balance, and eventually triggered the main shock with a magnitude of 5.4," he said.
He noted that there had been almost no prior seismic activity near the site, a key sign the quake was not natural. "If it had been a natural event, we would have observed recurring seismic activity before the main quake," he said. "Instead, almost no earthquakes occurred before the injections began, and afterward, clusters of microearthquakes appeared. That’s a clear sign of causation."
Kim outlined the sequence leading up to the main shock: drilling and fluid injection, a spike in microearthquakes, accumulation of fault stress, and finally, rupture. "When the fluid reduced friction on the fault surface and the accumulated stress passed its critical point, the fault ruptured," he said. The epicenter, he added, was located only about 600 meters from the injection well — a distance he said "supports this geological explanation."
He criticized the plant operator for continuing operations despite warning signs. "Even though microearthquakes repeatedly occurred during fluid injection, operations were not suspended, and there was no real-time monitoring system in place," Kim said. "Failing to act on such warning signs clearly shows poor management."
While emphasizing that geothermal energy remains a vital renewable source in the age of climate change, Kim cautioned that safety must come first. He called for mandatory real-time seismic monitoring and emergency shutdown procedures in future projects. "The Pohang case reminds us that technology and safety must progress together," he said.
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