Typhoon Francisco weakened Saturday and veered away from Japan's Pacific coast after forcing more than 1,000 people to take shelter on an island where rain-triggered mudslides left 43 dead or missing last week.

The centre of the storm, packing winds of up to 144 kilometres per hour, was located some 400 kilometres southeast of Tokyo at noon (0300 GMT) as it moved eastwards at 45 kilometres per hour, the Japan Meteorological Agency said.

Meanwhile, Typhoon Lekima, located further east and packing stronger winds, was also expected to be downgraded by Sunday morning.

On the volcanic island of Oshima, some 120 kilometres south of Tokyo, 1,300 people spent the night in public shelters for fear of more mudslides mixed with rock and volcanic ash.

"It has been raining overnight but no landslides or mudslides have been reported near main roads," an official of the Oshima town office said.

But the town mayor, Masafumi Kawashima , told local media: "Disasters involving earth and sand could occur after it stops raining. We will maintain vigilance."

The town issued an advisory to the island's entire population to take shelter against Francisco.

It has some 8,400 islanders but hundreds of them were thought to have left the island to avoid mudslides.

Evacuees on the island were further rattled by a 7.1-magnitude earthquake that rocked eastern Japan overnight triggering a small tsunami.

"I was too worried to sleep," fisherman Takayuki Koike told Jiji Press news agency at the Oshima municipal high school where more than 500 islanders were sheltered.

"I was not only worried about the mountain but also about the sea," said part-time worker Noriko Watanabe, 49, whose house was located on the waterfront.

The tsunami measured as high as 55 centimetres along the Pacific coast of eastern Japan.