SAPPORO (Kyodo) -- At least 32 people are missing after an earthquake with a preliminary magnitude of 6.7 rocked Japan's northernmost main island of Hokkaido early Thursday, causing mudslides that buried houses, authorities said.
The 3:08 a.m. quake also cut power supplies to nearly 3 million homes and a nuclear power plant in the prefecture while grounding flights and disrupting train services. More than 100 people were hurt in major cities including the prefectural capital of Sapporo, according to a Kyodo News tally.
A number of houses were buried in the towns of Atsuma and Abira following the quake after mountain slopes collapsed, according to the prefectural government and firefighters. The 32 missing people are all residents of Atsuma, police said.
The Nuclear Regulation Authority said Hokkaido Electric Power Co.'s Tomari nuclear power plant lost an external power source, with a spent fuel pool at its Nos. 1 to 3 reactors currently being cooled by an emergency power supply system.
No abnormality has been confirmed in radiation levels around the plant, regulators said. Meanwhile, Tohoku Electric Power Co. said no abnormalities were detected at the Higashidori nuclear power plant in Aomori Prefecture.
The power cut was caused by thermal power plants in the prefecture shutting down automatically after the quake. The blackout also affected around 40 hospitals, telephone service and television broadcasting in the prefecture.
A fire broke out at a petrochemical complex in Muroran and was later extinguished by firefighters.
The temblor, which occurred in southern Hokkaido at a depth of about 37 kilometers, logged upper 6 on the Japanese seismic intensity scale of 7 in the town of Abira and lower 6 in the city of Chitose, both southeast of Sapporo. It was followed by smaller aftershocks. No tsunami warning was issued.
The Japan Meteorological Agency warned that earthquakes with a similar intensity could continue in the area for about a week.
It was the first time for a quake in Hokkaido to reach an intensity of upper 6 since the seismic scale was revised in 1996.
"It messed up my entire house. I've never experienced an earthquake like this," an 87-year-old man in Atsuma said.
New Chitose Airport will be closed throughout the day after part of its terminal ceiling collapsed as well as due to the power outage, the transport ministry said, affecting flights to and from Tokyo and other cities.
Bullet train and local train services were also disrupted by the quake, operators said.
In Tokyo, the central government said the Self-Defense Forces will dispatch 25,000 personnel for relief operations at the request of the governor of Hokkaido.