Tokyo - A powerful earthquake rocked Japan's northernmost main island of Hokkaido early Thursday, triggering landslides that crushed homes, knocking out power and forcing a nuclear power plant to switch to a backup generator.
The magnitude 6.7 earthquake struck southern Hokkaido at 3:08 a.m. at the depth of 40 kilometres (24 miles), Japan's Meteorological Agency said. The epicentre was east of the city of Tomakomai but the shaking buckled roads and damaged homes in Hokkaido's prefectural capital of Sapporo, with a population of 1.9 million.
Chief Cabinet Secretary Yoshihide Suga told a news conference that two people had been confirmed dead. He did not give details.
The Japanese national broadcaster NHK, citing its own tally, reported that 125 people were injured and nearly 40 are feared missing. Hokkaido's local disaster agency put the number of injured at 48.
Several people were reported missing in the nearby town of Atsuma, where a massive landslide engulfed homes in an avalanche of soil, rocks and timber.
Reconstruction Minister Jiro Akama told reporters that five people were believed to be buried in the town's Yoshino district. Some of the 40 people stranded there were airlifted to safer grounds, NHK said.
Aerial views showed dozens of landslides in the surrounding area, with practically every mountainside a raw slash of brown amid deep green forest.
Police search for missing persons at the site of a landslide after an earthquake in Atsuma town, Hokkaido. Picture: Kyodo News via AP
Airports and many roads on the island were closed following the early morning quake. NHK showed workers rushing to clean up shattered glass and reinstall ceiling panels that had tumbled down in the region's biggest airport at Chitose.
Prime Minister Shinzo Abe said that 25,000 troops and other personnel would be dispatched to the area to help with rescue operations.
NHK showed the moment the quake struck the city of Muroran, with its camera violently shaking and all city lights going black moment later. In Sapporo, a mudslide on a road left several cars half buried.
Power was knocked out for Hokkaido's 2.9 million households. Economy, Trade and Industry Minister Hiroshige Seko told reporters that the extensive power outage was caused by an emergency shutdown of the main thermal power plant at Tomato Atsuma that supplies half of Hokkaido's electricity.
Japanese Prime Minister Shinzo Abe speaks to journalists following a strong earthquake, at his official residence in Tokyo. Picture: Yohei Fukai/Kyodo News via AP
The hope had been to get power back up "within a few hours," Seko said. However, damage to three generators at the Tomato Atsuma plant meant that the restoration of power could take more than a week.
Seko said utilities were planning to start up several other thermal and hydroelectric plants to provide at least some power.
In the meantime, authorities sent power-generator vehicles to hospitals so enable them to treat emergency patients, he said.
Reacting quickly to the disaster, troops deployed water tanker trucks in Sapporo, where residents were collecting bottles to tide them over until electricity and tap water supplies come back online.
The quake's impact was widespread. To the north, in the scenic town of Biei, residents lined up outside of supermarkets and convenience stores, quickly clearing shelves of water, toilet paper and food.
Residents watch a road damaged by an earthquake in Sapporo, Hokkaido, northern Japan. Picture: Hiroki Yamauchi/Kyodo News via AP
"Only a few cartons of instant ramen were left," said Mika Takeda, who lives in the town of 10,000. The one local gas station was limiting customers to only 20 litres (5 gallons) of gas, she said.
Suga said authorities were doing their utmost to rescue and assess damage after receiving hundreds of calls about people missing and buildings collapsing.
The central government set up a crisis management task force at the prime minister's office.
Members of disaster countermeasures office work at Hokkaido Government in Sapporo. Picture: Kyodo News via AP
Three reactors at the Tomari nuclear plant were offline for routine safety checks, but they are running on backup generators that kicked in after losing external power because of the island-wide blackouts, Japan's Nuclear Regulation Authority said. Spent fuel in storage pools was safely cooled on backup power that can last for a week, the agency said.
The powerful earthquake and tsunami in March 2011 that hit northeast Japan destroyed both external and backup power to the Fukushima Dai-ichi nuclear plant, causing meltdowns.