Japanese rescue workers with bulldozers and sniffer dogs scrabbled through the mud Friday to find survivors from a landslide that buried houses after a powerful quake, as the death toll rose to 18.
Around 22 people are still unaccounted for in the small northern countryside town of Atsuma, where a cluster of dwellings were wrecked when a hillside collapsed with the force of the 6.6-magnitude quake, causing deep brown scars in the landscape.
"We've heard there are people still stuck under the mud, so we've been working around the clock but it's been difficult to rescue them," a Self-Defense Forces serviceman in Atsuma told public broadcaster NHK.
"We will take measures to find them quickly."
An elderly woman in Atsuma told NHK: "My relative is still buried under the mud and has not been found yet, so I couldn't sleep at all last night. There were also several aftershocks so it was a restless night."
Around 1.6 million households in the sparsely populated northern island of Hokkaido were still without power after the quake damaged a thermal plant supplying electricity to the region.
Industry minister Hiroshige Seko said that number should be reduced to 550,000 households on Friday.
"It will take about a week" before the largest thermal power plant recovers, "so during that period, we are sending power-generating vehicles to hospitals," Seko told reporters.
He urged citizens to conserve energy by having fewer lights on in shops and restaurants and "for example family members staying together in one room".
Some 22,000 rescue workers including troops called up from the Self-Defense Forces handed out emergency water supplies and long lines formed at petrol stations and supermarkets, as people stocked up fearing further quakes.
"Please give your sympathy to people who spent a dark night in fear, and do everything you can to restore electricity as soon as possible," Prime Minister Shinzo Abe told a cabinet meeting to discuss the quake.
The earthquake, which scored the maximum on a Japanese scale measuring the power of a quake's shaking, also collapsed a handful of houses and walls in the main city of Sapporo.
However, considering the strength of the quake, the death toll was relatively light, with the majority of victims coming from the landslide in Atsuma.
Transport services were gradually coming back on line with bullet trains resuming operations late Friday morning and the main airport in Sapporo operating a partial service after cancelling all flights the day before.
But a football friendly between Japan and Chile in Sapporo planned on Friday was scrapped due to the transport and power chaos in Hokkaido.
The quake was the latest in a string of natural disasters to batter the country.
Western parts of the country are still recovering from the most powerful typhoon to strike Japan in a quarter of a century, which claimed 11 lives and shut down the main regional airport.
And officials warned of the danger of fresh quakes.
"Large quakes often occur, especially within two to three days (of a big one)," said Toshiyuki Matsumori, in charge of monitoring earthquakes and tsunamis at the meteorological agency.
The risk of housing collapses and landslides had increased, he said, urging residents "to pay full attention to seismic activity and rainfall and not to go into dangerous areas".
Japan sits on the Pacific "Ring of Fire" where many of the world's earthquakes and volcanic eruptions are recorded.
In June, a deadly tremor rocked the Osaka region, killing five people and injuring over 350.
On March 11, 2011, a devastating 9.0-magnitude quake struck under the Pacific Ocean, and the resulting tsunami caused widespread damage and claimed thousands of lives.