South Korean earthquake tied to geothermal injection

The magnitude 5.4 Pohang earthquake that occurred near a geothermal site in South Korea last year was likely triggered by fluid injection at the geothermal plant, two separate reports conclude.

While activity from Enhanced Geothermal System (EGS) sites – which inject large amounts of water underground – has been associated with much smaller earthquake events, the magnitude of the 2017 quake would make it the largest-known earthquake induced at an EGS site. The Pohang earthquake was the most damaging quake in South Korea since the first seismograph was installed in 1905. After the quake in November, researchers began to assess whether it was induced by activity at a nearby EGS location, where many thousands of cubic metres of water had been injected at high pressure starting in 2016.

Though induced quakes have been well-established in places like Oklahoma, such regions involve oil and gas extraction, not geothermal activity. Researchers have developed a family of synthetic polymers that can be repeatedly recycled. Globally, the output of plastic is expected to exceed 500 million tons by 2050. While most plastics are produced for single-use applications, these materials will persist in the environment for centuries.

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