Two consecutive earthquakes occurred 11 kilometers northeast of Goesan in North Chungcheong Province at 8:27 a.m., according to the Korea Meteorological Administration (KMA). Yonhap

A 4.1 magnitude earthquake struck South Korea's central county of Goesan on Saturday, the weather agency said, with no damage or casualties reported so far.

The quake occurred in the village of Jangyeon, northeastern Goesan of North Chungcheong Province, at 8:27 a.m. with an estimated depth of 12 kilometers, according to the Korea Meteorological Administration (KMA).

The KMA initially announced the earthquake's measured strength at 4.3 but later revised it to 4.1.

It marks the strongest earthquake ever to hit the Korean Peninsula this year and the 38th largest of all time in the country. It also was the strongest quake following a 4.9 magnitude one that hit waters off Seogwipo on the southern resort island of Jeju on Dec. 14 last year.

The 4.1 magnitude quake was preceded by three foreshocks of magnitude 1.6, 1.3 and 3.5, all minutes before the larger one was reported, according to the KMA. There were 12 aftershocks reported until 10 a.m., it added.

According to officials, a 5 magnitude tremor was apparently noticed throughout the province.

The KMA said the earthquake appears to have occurred due to a strike-slip fault moving in the direction of north-northeast and south-southwest or east-southeast and west-northwest. A strike-slip fault refers to a fault that usually moves horizontally.

The central disaster management headquarters said it has yet to receive any reports of damage or casualties while the National Fire Agency said it has received 168 reports nationwide from callers who felt the tremors or asked about them.

The Nuclear Safety and Security Commission said there were no safety issues with the country's nuclear reactors due to the earthquake.

The Hanaro research reactor, located 69 km from the quake's epicenter and the closest nuclear facility to it, did not detect seismic activity strong enough to issue an alert, it added.

In such adjacent cites of Cheongju and Chungju, however, some citizens hastily escaped to safety out of their homes after experiencing relatively large tremors.

"I heard a sound of a bomb explosion and the house shook a lot," a resident of Goesan told Yonhap News Agency. "Although the furniture did not fall off, it was the first time in my life that I experienced this big of a shake from an earthquake."

Another resident at a market in Chungju said some 20 people were evacuated after the tremors were felt.

A dormitory at Semyung University in Jecheon, North Chungcheong Province, suffered a power outage after the quake, with smoke being reported from an unidentified source, prompting some 70 people to evacuate.

The tremors were apparently sensed even from Seoul, 110 km away from Goesan, with some citizens reporting to the fire authorities that they felt the ground shake for about two seconds.

President Yoon Suk-yeol instructed all government offices related with disaster management affairs to apprehend possible damage from the quakes, including any disruptions to infrastructure facilities such as electricity and communications, his spokesperson said in a written press briefing.

Including the latest one, 61 quakes with a magnitude of 2 or higher have struck the country since the beginning of the year, with most of them milder than a magnitude of 3.

The largest earthquake that has been reported within a 50-kilometer radius of the epicenter of Saturday's tremors since 1978 was a 5.2 magnitude one that occurred in September of that year. (Yonhap)