Multiple, large-scale landslides struck the sparsely populated countryside, which was also hit by the edge of a powerful typhoon that surged through Japan earlier this week.
Aerial views showed dozens of houses destroyed at the bottom of a hill, with a rescue helicopter winching a resident to safety.
Around three million homes lost power after the quake damaged a major thermal plant supplying the region.
The Tomari nuclear power plant in Hokkaido, which was not operational before the quake, was forced to turn to emergency back-up power to keep its cooling system working, NHK said.
Kazuo Kibayashi, a town official at hard-hit Abira town, told AFP: “There was a sudden, extreme jolt. I felt it went sideways, not up-and-down, for about two to three minutes.”
“It stopped before shaking started again. I felt it come in two waves. I am 51, and I have never experienced anything like this. I thought my house was going to collapse. Everything inside my house was all jumbled up. I didn't have time to even start cleaning,” he added.
Moments after the initial quake, an aftershock measuring 5.3 rocked
