An earthquake measuring 4.5 on the Richter scale rattled the historic city of Gyeongju on Monday evening, an aftershock of an even bigger quake last week. The quake could be felt across North Gyeongsang Province and as far away as Gangwon Province and Seoul. The Korea Meteorological Administration said the tremor occurred at around 8:33 p.m. and was an aftershock of the 5.8-magnitude earthquake that jolted the historic city on Sept. 12. It was the most-powerful aftershock on record in Korea and equivalent in magnitude to 3,000 tons of TNT.



Residents gather outside apartment buildings in Busan after an earthquake on Monday. /Yonhap

The damage was minor and the aftershock seems to have occurred toward the end of a series of some 380 aftershocks since Sept. 12. People nonetheless ran out of their homes and emergency services were inundated with around 11,000 phone calls an hour. The KMA said tremors lasted for 10 seconds in Gyeongju, Pohang, Daegu and other parts of North Gyeongsang Province.

Evacuatees warm themselves with blankets at an elementary school in Hwangseong, Gyeongju in South Gyeongsang Province on Monday. /Yonhap

Ji Heon-cheol at the Korea Institute of Geoscience and Mineral Resourses said, "Forecasts that aftershocks would not exceed 3.0 in magnitude were proven wrong." And Seon Chang-guk at said, "Aftershocks lasted for more than a year after the major earthquake that rocked eastern Japan in 2011 and are still being detected after the Kumamoto earthquake in April this year, so there is a strong chance that aftershocks will continue here too." Hong Tae-kyung at Yonsei University said the fault lines under the Korean Peninsula changed due to the 2011 earthquake in Japan and the earthquake in Gyeongju delivered further impact, "so nobody knows what is going on underneath us."