A powerful 5.4-magnitude earthquake hit the southern region of South Korea Monday evening, the US Geological Survey (USGS) said, following an earlier quake of 4.9-magnitude.
The Korea Meteorological Administration put the second tremor higher than USGS, at 5.8-magnitude.
The quake hit at around 8:30 pm (1130 GMT), with the epicentre near the southeastern city of Gyeongju.
No casualties or injuries have been reported yet, Yonhap news agency quoted the ministry of public safety as saying.
The powerful tremor was felt in the port city of Busan, with residents in high-rise apartments rushing out in shock, Yonhap said, and was even felt as far away as the capital Seoul.
"There was a spike in people calling authorities to find out about the quake," Yonhap reported after the first tremor.
On Friday USGS reported a 5.3-magnitude "artificial earthquake" in North Korea, that was in fact a nuclear test.