Korea Meterological Administration staff monitor the impacts of a 3.9 magnitude quake that occured in Ganghwa, west of Seoul, on Jan. 9. (KMA via The Korea Herald/Asia News Network)
SEOUL — South Korea, located on the relatively stable Eurasian Plate, has generally been considered safe from earthquakes.
But authorities and experts here are voicing concerns that it is not a safe zone anymore, citing the growing number of earthquakes detected in recent years, changes in geology making Korea more vulnerable to big quakes in nearby regions, and most importantly, inefficient regulations that could minimize the damage if a quake happens.
According to Korea Meteorological Administration’s annual report released on Wednesday, Korea detected a total of 77 earthquakes with magnitude above 2 last year, a 10 percent increase from a year before.
Of the total, the country had eight earthquakes above magnitude 3 — a level at which people start to feel earthquakes but damage is rare. This included a magnitude 4 quake that occurred in Goesan, North Chungcheong Province, in Oct. 29.
The quake was the largest since a 5.4 magnitude earthquake that struck the southeastern city of Pohang in 2017 that caused significant damage and injured dozens of people, according to the agency.
“The quake in Goesan is a case that shows an earthquake causing damages can occur in any places in South Korea,” said KMA chief Yoo Hee-dong. “We should be ready for earthquakes always with thorough preparations,” he said, stressing the need to secure prevention measures and scientific research for the next generation.
Experts, however, said Korea is still lack of basic research and countermeasures to protect people from earthquakes.
Hong Tae-kyung, a director of Earth System Sciences Research Center and Earth System Sciences Professor of Yonsei University, said that Korean peninsula has been shaken up by the 2011 Tohoku earthquake and tsunami, which caused more than 15,000 casualties and disastrous consequences including the Fukushima nuclear power plant explosion.
“The Tohoku earthquake in 2011 dragged the Korean Peninsula toward Japan, stretching the peninsula about 3 centimeters from east to west. This means that the Korean Peninsula has become a loose land, in other words, a land in which it requires less force for an earthquake to occur than before,” explained Hong.
Hong explained that this does not mean a new risk of earthquakes happening, but that the earthquakes that would happen anyway would occur earlier than before due to the loosened ground.
“The probability of an earthquake has not changed, but the ground situation in Korea has changed due to the big earthquake, and we need to be prepared,” Hong said.
Professor Kim Young-Seog of Pukyong National University, a well-known researcher for alerting the danger of an earthquake based on historical record just before the Gyeongju earthquake in 2016, emphasized that there are numerous historical records about the potential of big earthquakes in Korean peninsula.
“Stress inside the ground is always being accumulated, and at some point it must explode. We just don’t know about a big earthquake because it happens through a long cycle, but there’s plenty of evidence historically and geologically (about the possibility of big earthquake in Korea).”
In this situation, Cho Won-cheol, a civil engineering professor at the Yonsei University, said a geological investigation to figure out the location and number of faults should be carried out to effectively protect people from earthquakes.
“Many other countries have already kicked off investigation for fault — where most of earthquakes occur — in their country. The United States, for example, has been steadily investigating faults for nearly 300 years, but Korea’s fault investigation is still insufficient,” Cho said.
“It will take a lot of budget, but we should think of it as an investment to prevent huge damage in the future. But so far, Korean government, compared to other countries, seems to think that (geological research) is a waste.”
Professor Kim of Pukyong University echoed Cho’s claim.
“Dangerous facilities like nuclear power plants or spaces where people always stay, such as schools and apartments, should not be built on faults. Maps that show the locations of faults are necessary to avoid dangerous areas,” said Kim.
Kim said that the nation’s active faults — the fault that has caused earthquake within 2.58 million years, and has potential to cause an earthquake — is currently under investigation, but still at the starting point.
“Earthquake-resistant construction, which is the most representative countermeasure that people think of, is of no use if the ground splits in the event of a massive earthquake. Avoiding dangerous areas in the first place is the effective way,” said Kim.
Experts also pointed out the danger of old buildings that have no seismic reinforcement technology.
“Old facilities, which account for more than 80 percent of nation’s facilities, were built in a time when there were no earthquake resistance construction regulations, and common masonry buildings without reinforcement will collapse in an earthquake only half as strong as the Turkey earthquake,” said Cho.
This is still much stronger than recent earthquakes in Korea. The recent quake in Turkey was magnitude 7.8, more than 100 times stronger than the one in Gyeongju.
In addition to improving seismic reinforcement technologies, state and private support are also necessary, Cho added. “Both the state and the private sector need to work together, giving incentives — lowering taxes or insurance fees — to encourage building owners make earthquake-resistant reinforcements,” he said.
Unfortunately, there is no technology to predict earthquakes yet, said professor Kim of Pukyong University. Only early warning is available, which is to detect the first vibration that spreads when an earthquake occurs and alert people to evacuate just before few seconds to few minutes.
As for the premonitory symptoms of earthquakes, animals suddenly moving in groups or strange shaped clouds displayed, Kim said they are yet to be scientifically proven.
“It doesn’t appear the same for every earthquake, and in some cases it doesn’t happen at all,” he said.
He said the important thing for earthquake prediction is the technology to monitor minute changes.
“There is always a tremor before a big earthquake and composition of groundwater or gas underground may change before an earthquake. We should endeavor to improve techniques for predicting earthquakes by monitoring these minor changes,” advised Kim.
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