At least two people are dead and some 20 people are missing after a mudslide swept across a seaside city about 100 kilometres south-west of Tokyo, sweeping away homes amid Japan's rainy season.
Footage posted on social media showed the powerful black mudslide shoot down a mountainside, engulfing homes and infrastructure as locals watched in horror.
The giant mudslide in Atami, Shizuoka prefecture, which occurred about 10.30am (11.30am AEST) on Saturday, came after parts of the region were hit by torrential rain.
An Atami city official confirmed to CNN that two women had died in the landslide.
Police and firefighters have been searching for the missing and so far 19 people have been rescued in Atami city after being stranded in their homes.
Operations stopped overnight and resumed on Sunday at 6am (7am AEST), with 700 people from the police, fire department service and Japan Self-Defence Forces assisting.
As of 6.30am (7.30am AEST), some 380 people had been evacuated, and 10 evacuation centres had been opened in the city, the Atami city official said.
More than 130 houses were swept away in the mudslide, Atami's Fire Disaster and Management Agency said. Sakae Saito, the mayor of Atami city, told reporters that up to 100 to 300 households were affected.
About 2830 households in the city lost power, according to the Tokyo Electric Power Company. By Sunday, power had mostly been restored in Shizuoka.
Atami resident Yuji Shima managed to evacuate with his wife and mother but said he lost his home in the mudslide, which looked "like a tsunami."
"The first thing that struck me was the sound of the ground rumbling. There was such a muddy, chemical stench in the air - of course as so many things were being washed away. It all happened in a split-second," he said.
Mr Shima said he'd lived in the area for 50 years and though he'd experienced typhoons and heavy rains, he had "never lived through anything like this."
"I prioritised my family's safety. We just got ourselves here and didn't take anything with us. We had a lot of people helping us so we had access to food and water," he said.
"It's a blessing I survived."
The government has set up a task force to respond to the disaster and collect information as heavy rainfall sweeps areas along the Pacific coast in central and eastern Japan.
Japanese Prime Minister Yoshihide Suga expressed his condolences to the victims of the landslide and stressed that emergency workers were doing their utmost to save lives, rescue people and help with evacuations.
Mr Suga added that the seasonal rain front would continue to bring heavy rain to various parts of the country. He urged citizens to check hazard maps in their local areas, pay close attention to weather updates and evacuation information and make sure to take action to protect lives.
Heita Kawakatsu, the governor of Shizuoka prefecture, expressed his "deepest sympathies" to those affected by the landslide and to "those who have been forced to evacuate."
Mr Kawakatsu warned more rain was expected and said residents should watch out for further landslides.
"There are many places where the ground is loose, so please evacuate from dangerous places, listen to information from the city and town, and make sure you and your family are safe," he told a Saturday press conference.
Taiwan's Ministry of Foreign Affairs issued a message of support to the Japanese government on Twitter on Saturday, saying Taiwanese people "were shocked and extremely saddened by the news footage that was broadcast. If Japan needs it, we are ready to provide assistance."
https://twitter.com/MOFA_Taiwan/status/1411249422529294336So far, evacuation orders have been issued for people in areas surrounding Tokyo, as well as in Shizuoka, and Aichi prefectures, according to Japan's public broadcaster NHK.
The authorities have issued landslide warnings for parts of Shizuoka, Kanagawa, Chiba and Yamanashi prefectures, NHK reported.
The rain front was expected to move toward the Sea of Japan coast over the weekend, with areas along the coast forecast to see torrential rain on Monday and Tuesday, according to Japan's Meteorological Agency, which also warned of landslides and flooding in low-lying areas.
Japan is prone to landslides, averaging up to 1500 landslides annually in the past decade - an almost 50 per cent increase compared to the previous 10 years, according to a 2020 Japanese government report.
Flooding-related disasters, like landslides, are a traditional yet serious risk to the country. This is because half of the Japanese population and 75 per cent of the country assets are concentrated in flood-prone areas, according to experts.
"Japan has a whole lot of risk factors leading to landslides. For instance, it's prone because of its mountainous terrain and a lot of places where the soil is volcanic ash, which is not as strong," seismologist Robert Geller, professor emeritus of the University of Tokyo, told CNN.
A rise in rainfall due to global warming is increasing the risk of devastating mudslides.
"Global warming is making everything worse and is increasing the frequency of rainfall that can cause damaging landslides," Professor Geller added.
"The rainy season is going to last for another week or 10 days. Because of global warming, we're probably getting more rainfall now than we normally do."
