A Japanese seismologist has advised residents in parts of Miyagi and Fukushima prefectures to remain alert for the possibility of further strong shaking following a magnitude 7.3 earthquake that hit the region on Wednesday night.

University of Tokyo Professor Emeritus Hirata Naoshi said seismic activity in the area where the quake occurred has continued since the 2011 Great East Japan Earthquake.

He said accurate information about the epicenter is not yet known, but judging from the temblor's depth, it likely struck either near the edge of the sinking Pacific plate, or within the plate.

He said another quake of a similar scale could hit again, and he warned people to be cautious about potential jolts.

He also said people should remain in safe places, as old buildings damaged by the quake were at risk of collapse.