March 25, 2019– Mary Greeley News – South Korea’s second-most destructive earthquake, which struck the southeastern city of Pohang in 2017, was probably triggered by an experimental geothermal power plant, the government said Wednesday.
The government-led teams of experts, from both South Korea and abroad, concluded that a series of earthquakes, reaching a magnitude of 5.4 on Nov. 15, 2017, could have been brought on by efforts to harness energy from the ground.
The project is in Pohang, a city on the coast in the Southeast of the Korean Peninsula and was to be fueled by a well drilled to a depth of around 4,000 meters.
Supported through the country’s Ministry of Trade, Industry & Energy, the project started in 2011 and has seen an investment of $38 million (South Korean Won 43.2 billion) with $16 million provided from government funding and $22 million from private investors.
The study is the first official government finding that indicated the possible cause of the tremors that resulted in considerable damage in and around the industrial city, located 375 kilometers southeast of Seoul.
Fluids were injected at high pressure into a hole about four and five kilometers deep at the geothermal power plant, which may cause the surrounding rock to crack, the scientists said. During the process, seismic activity can occur, which could cause earthquakes.
“A series of micro-sized earthquakes occurred when fluids were injected by excavating a geothermal well at the geothermal power plant, which eventually triggered the Pohang earthquake,” Lee Kang-keun said
The government-led team was offered two separate assessments though both found the plant ability to trigger a tremor as being plausible.
“We use the word, trigger, as the earthquake occurred beyond the scope of stimulated area,” Lee said. “It was not a natural earthquake.”
The Pohang quake was the most disruptive to hit the country since observations began in 1978. The temblor left dozens of people injured and more than 2,000 homes damaged.
The strongest quake, which occurred in September 2016, reached a magnitude of 5.8 and had its epicenter near a township south of Gyeongju, 370 kilometers south of Seoul.
Officials said regions in Pohang were found to have the optimal conditions for generating geothermal electricity, with some reaching 180 degrees Celsius at a depth of five kilometres. In a typical volcanic area, the temperature reaches 150 degrees at a depth of one kilometer.
credit: In part with https://en.yna.co.kr/view/AEN20190320002451320?section=science/science