An expert warns that jolts of similar scale to the magnitude 5.2 earthquake in Chiba Prefecture that struck early Thursday may occur for about a week.
Professor Satake Kenji at the University of Tokyo's Earthquake Research Institute spoke to NHK.
He pointed out that the Pacific Plate from the east and the Philippine Sea Plate from the south move toward the Kanto region, which includes Tokyo. He said the region tends to see frequent seismic activity as a result.
Satake said he believes that the quake this time was likely triggered by movement of the Philippine Sea Plate, and such quakes often occur in the region.
The professor said tremors of similar intensity could hit the Kanto region for about a week.
He called on residents to remain on alert for possible strong earthquakes.