Officials say 18 people died or are presumed dead after a powerful earthquake on Japan's northernmost main island of Hokkaido unleashed scores of landslides, burying homes in avalanches of soil, rock and timber.

Police officers search for survivors from a house damaged by a landslide caused by an earthquake in Atsuma town, Hokkaido, northern Japan, in this photo taken by Kyodo September 7, 2018. (Photo: VCG)

Searchers were digging through the mountains of debris Friday near a small mountain town hoping to find survivors, with 19 people still unaccounted for after the magnitude 6.7 quake struck early Thursday.

Prime Minister Shinzo Abe said nearly half of the households have had their power restored after a day of island-wide blackouts.

The regional government said the bullet train to the provincial capital, Sapporo, was due to reopen later in the day. But damage to some parts of the city was severe, with houses atilt and roads crumbled or sunken.