A 4.6-magnitude earthquake shook the North Gyeongsang province in southeast South Korea, the weather service said Sunday.
The tremor hit an area, 5 km northwest of the northern district in the country's south-eastern coastal city of Pohang at about 5:03 am local time (2003 GMT Saturday), according to the Korea Meteorological Administration.
The epicentre, with a depth of 14 km, was at 36.08 degrees north latitude and 129.33 degrees east longitude.
The weather agency believed that it was an aftershock of the country's second-strongest quake that hit the Pohang city on Nov 15 last year. The seismic intensity of the Nov 15 tremor was 5.4 magnitude.
No life-threatening injury was reported, says Xinhua news agency.
According to local media reports, 22 people sustained minor injuries.