A record-breaking earthquake has raised safety concerns over nuclear reactors in South Korea, despite meteorological chief saying that larger earthquakes are unlikely.

Ko Yun-hwa, the head of the Korea Meteorological Administration said on Tuesday morning that strong earthquakes exceeding a magnitude of 6.5 are unlikely to occur in South Korea although earthquakes of magnitudes higher than 6 could happen in the future.


Following the 5.8 magnitude earthquake in the southeastern city Gyeongju on Monday night -- the largest on record -- there were more than 200 aftershocks ranging between a magnitude of 2.0 and 4.0, according to the KMA on Tuesday. The KMA warned that aftershocks may continue for three or four days.

As South Korea witnessed its strongest earthquake on record, experts raised concerns over nuclear reactors in the country.

Environmental activists, including the Korean Federation for Environmental Movement, urged the government to immediately cease operations of nuclear reactors and revamp its nuclear policy.

“The epicenter of the quake is only 27 kilometers away from the nuclear reactor clusters and it is very dangerous,” a statement issued by KFEM said, adding that “The government should make sure that the nuclear plants are safe from stronger earthquakes.”

During a radio interview, a KFEM employee said that nuclear plant operations should have been immediately halted after the earthquake.

The Korea Hydro & Nuclear Power, which operates the country’s nuclear plants, shut down four nuclear reactors only 20 kilometers away from the epicenter for safety inspections four hours after the earthquake.

The KHNP said the operations of Wolsong No. 1, Wolsong No. 2, Wolsong No. 3 and Wolsong No. 4, which have a combined capacity of 2,779 megawatts, were halted as the acceleration of gravity felt at the plant reached 0.1 g in accordance with its manual.

Hanul and Gori plants, also located close to the epicenter, are not closed, according to the KHNP.

Experts warned of the safety of nuclear reactors in the country amid the increased frequency of tremors that have been felt over the past few years. This year alone there was more than 20 earthquakes detected in South Korea.

“Despite most earthquakes not being too dangerous, it is still worrisome that the numbers of such shocks have been rising,” Chi Heon-cheol, a researcher at Korea Institute of Geoscience and Mineral Resources said, adding that the number of tremors being detected throughout the country is higher than previously anticipated.

President Park Geun-hye on Tuesday vowed to better equip key facilities, including nuclear reactors, to withstand earthquakes.

By Park Ga-young (gypark@heraldcorp.com) and news reports