Geothermal woes

Gee - it turns out it's best not to play around with geothermal energy in earthquake prone places:

A South Korean government panel has concluded that a magnitude-5.4 earthquake that struck the city of Pohang on 15 November 2017 was probably caused by an experimental geothermal power plant. The panel was convened under presidential orders and released its findings on 20 March.

Unlike conventional geothermal plants, which extract energy directly from hot underground water or rock, the Pohang power plant injected fluid at high pressure into the ground to fracture the rock and release heat — a technology known as an enhanced geothermal system. This pressure caused small earthquakes that affected nearby faults, and eventually triggered the bigger 2017 quake, the panel found.

The quake was the nation’s second strongest and its most destructive on modern record — it injured 135 people and caused an estimated 300 billion won (US$290 million) in damage.