A TV program called Hodo Station reports that aftershocks of about 6- on the Japanese scale can be expected for about a week. Here’s the description of 6- (6-lower) provided by Wikipedia:
Difficult to keep standing. A lot of heavy and unfixed furniture moves and falls. It is impossible to open the door in many cases. All objects will shake violently. Strongly and severely felt outside. Light posts swing, and electric poles can fall down, causing fires. Less earthquake-resistant houses collapse and even walls and pillars of other homes are damaged. Apartment buildings can collapse by floors falling down onto each other. Less earthquake-resistant buildings easily receive heavy damage and may be destroyed. Even highly earthquake-resistant buildings have large cracks in walls and will be moderately damaged, at least. In some buildings, wall tiles and windowpanes are damaged and fall. Gas pipes and/or water mains will be damaged. Gas, water and electricity are interrupted. Small to medium cracks appear in the ground, and larger landslides take place. 2.50–3.15 m/s² VIII-X
https://en.wikipedia.org/wiki/Japan_Meteorological_Agency_seismic_intensity_scale