Authorities say 166 aftershocks were recorded following the massive five-point-eight magnitude earthquake that jolted the region near Gyeongju City at 8:32 p.m. on Monday.

An official at the Korea Meteorological Administration(KMA) said that as of 5 a.m. Tuesday, the main quake was followed by 153 aftershocks with a magnitude of two to three, 12 quakes with a magnitude of three to four and one with a magnitude of four to five.

The official said that bigger earthquakes have more and larger aftershocks, adding that aftershocks may continue for days or weeks and it’s impossible to predict when they will stop.

As of 1 a.m. Tuesday, 111 aftershocks occurred and 55 aftershocks with the seismic intensity of two to three followed.