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A group of Australians on a surf charter boat off Sumatra jumped into the water when a three-metre high wave, generated by an undersea quake, forced another boat into their craft, causing an explosion.
The major 7.7-magnitude undersea quake hit Kepulauan Mentawai, off the west coast of Indonesia, at 9.42pm (0342 NZDT) on Monday, seismologists said, but there were no reports of damage or casualties. A tsunami warning was issued, before being cancelled.
Australian man Rick Hallet, who has a charter boat operation in Sumatra, told the Nine Network 15 people, including nine Australians, were on the back deck of the boat in the bay off Mentawai Islands when they felt what they thought was a quake.
"Within several minutes a large wall of white water came through the bay and took us out essentially," he said.
"It was night time around about 10pm ... a two to three metre wall of white water came into the bay and there was another boat anchored out the side of us ... the wave picked that boat up and brought it towards us and ran straight into us and our boat exploded, caught on fire, we had a fireball on the back deck and right through the saloon within seconds," he said.
He said the group had been on the back deck, relaxing and playing music before the wave hit.
"I ordered everyone up to the top deck to get as high as possible, then the boat exploded and we had to abandon ship," Mr Hallett said.
"We threw whatever we could that floated - surfboards, fenders - then we jumped into the water.
He said the jumped into the water and several of them were swept 200 metres inland by the wave and sheltered in high trees until they were rescued by another boat 90 minutes later.
"We stayed up in the trees until we felt there was no more risk of waves or big surges coming through," he said.
He said all 15 people on the boat had been accounted for.
The undersea quake hit Indonesia's Kepulauan Mentawai region at a shallow depth of 20km, the US Geological Survey said.
The area is 240km west of Bengkulu on Sumatra island and 280km south of Padang - an area popular with tourists.
The quake was followed by a powerful 6.1-magnitude aftershock about five hours later in the same area.