Japan's Meteorological Agency has urged residents in Hokkaido to remain vigilant after an earthquake hit the northernmost prefecture Friday morning.
Toshiyuki Matsumori, the official in charge of monitoring earthquakes and tsunami, spoke to reporters after the tremor, which registered an intensity of 5-minus on the Japanese scale of zero to seven.
Matsumori said the quake may have increased the risk of landslides and collapsed buildings in hard-hit areas.
He urged people to be prepared for future jolts and rain as they engage in recovery work.
He said strong tremors could occur at any time.