Nuclear reactors unaffected after minor earthquakes in Haenam

Over 70 minor earthquakes recorded in the southern region over the past 10 days

A magnitude 3.1 earthquake that struck Haenam, Jeonnam-Gwangju, early Sunday had no impact on the country’s nuclear power plants, nuclear authorities said.

The earthquake struck an area 21 kilometers west-northwest of Haenam at 6:43 a.m., according to authorities.

The earthquake was not strong. The US Geological Survey describes a magnitude 3 quake as like "the vibrations caused by a passing truck" — quite noticeable but not always recognized as an earthquake.

Korea Hydro & Nuclear Power said all nuclear power plants currently in operation were functioning normally following the quake.

“All nuclear power plants currently in operation are operating normally,” KHNP said in a statement Sunday, adding that seismic readings at the facilities remained below the earthquake alarm threshold of 0.01 g.

The Nuclear Safety and Security Commission separately said it had confirmed that the earthquake had caused no abnormalities at any nuclear reactor facilities in the country.

Hanbit Nuclear Power Plant, the reactor facility closest to the epicenter at approximately 83.2 kilometers away, recorded ground acceleration of 0.0032 g.

The figure was far below the plant’s seismic design level of 0.2 g and was not high enough to affect the facility, the commission said.

An emergency safety inspection conducted at Hanbit by the commission’s regional office also found no abnormalities.

The quake comes amid a series of recent tremors in the same area.

Seven earthquakes of magnitude 2.0 or greater have occurred west-northwest of Haenam over the past 10 days. Including smaller tremors, 71 earthquakes have been detected in the area during the period.

The area experienced a similar sequence in 2020, when 76 earthquakes were recorded, with the strongest also reaching magnitude 3.1.

In a report examining the 2020 sequence, the Korea Institute of Geoscience and Mineral Resources said the earthquakes were believed to be associated with a group of small- to medium-sized faults.

The institute said at the time that the likelihood of the activity developing into a major earthquake was low, while stressing the need for continued monitoring.