Is this the end for ‘enhanced’ geothermal technology? Note this quake was 1,000 times stronger than the next one of similar causes.
The nation’s energy ministry expressed ‘deep regret’, and said it would dismantle the experimental plant, as Nature News reports.
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.
The nation’s Ministry of Trade, Industry and Energy, which had provided funding for the plant, said in a statement that it accepts the panel’s findings and “expresses deep regret” to the citizens of Pohang who were harmed by the event.
Full report here.
As far as can be gleaned from the Nature news report no empirical evidence is shown, just the usual ‘it’s happened before’ correlation attribution. Could not have this enhanced geothermal operation (EGS) have had only a minor effect on the bigger earthquake? It’s hard to tell by reading the Nature news report.
The reports “Assessing whether the 2017 Mw 5.4 Pohang earthquake in South Korea was an induced event” by Kwang-Hee Kim, Jin-Han Ree, YoungHee Kim, Sungshil Kim, Su Young Kang, Wooseok Seo says —
“The possibility remains that the earthquake occurred coincidentally at the EGS site location…”
See http://science.sciencemag.org/content/360/6392/1007
And this paper is at Science 01 Jun 2018: Vol. 360, Issue 6392, pp. 1007-1009
DOI: 10.1126/science.aat6081 where it reveals a little more of geological investigation that was ongoing when EGS trials were taking place and after. It would now appear to be foolhardy to perform enhanced geothermal operations (or fracking), in seismically active areas (other examples they cite are Cerro Prieto in Mexico and Basel in Switzerland).