7-magnitude quake struck in the Mentawai Islands area west of Sumatra late Monday, generating waves as high as three metres (10 feet) that swept away 10 villages.
Hendri Dori Satoko, a lawmaker in the Mentawai Islands, told MetroTV: “Our latest data from the crisis centre showed that 108 people have been killed and 502 are still missing.”
Disaster Management Agency spokesman Agolo Suparto said: “Ten villages have been swept away by the tsunami.”
As the rescue operation intensified, Indonesia’s most active volcano Mount Merapi erupted three times on Tuesday, causing thousands to flee in panic and claiming the lives of 13 people.
“We heard three explosions around 6:00 pm (1100 GMT) spewing volcanic material as high as 1.5 kilometres (one mile) and sending heat clouds down the slopes,” government volcanologist Surono told AFP.
Indonesia sits on the Pacific “Ring of Fire”, where the meeting of continental plates causes high volcanic and seismic activity.
A 7.6-magnitude earthquake in September last year in Padang killed about 1,100 people while the 2004 Asian tsunami — triggered by a 9.3-magnitude quake off Sumatra — killed at least 168,000 people in Indonesia alone.
Health Ministry Crisis Centre head Mudjiharto said the Mentawai waves reached up to three metres high and waters swept as far as 600 metres inland on South Pagai island, the hardest hit.
“Eighty percent of buildings in Muntei village have been damaged by the waves and many people are missing there,” Mudjiharto said.
He said medical personnel were on their way to the worst-hit areas in helicopters but rescue efforts had been hampered by disruption to communications in the region.
Disaster Management Agency aid coordinator Wisnu Wijaya told AFP that rescue teams from the capital Jakarta would join forces with local teams to evacuate bodies and deliver food aid, medicines, tents and blankets.
Rescuers launched a search for a boat believed to be carrying a group of nine Australians and a Japanese national that has been missing since the quake.
A group of Australian tourists reported that their boat with 15 people aboard was destroyed by a “wall of white water” crashing into a bay after the undersea quake and said some had to cling to trees to survive.
Rick Hallet, an Australian who operates a boat-chartering business in Sumatra, recounted his group’s ordeal when the quake struck.
“The bay we were in was several hundred metres across and the wall of white water was from one side to the other, it was quite scary,” he told Fairfax Radio Network.
Yogyakarta city search and rescue official Taufiq told reporters that 12 bodies were found near Mount Merapi in and around the “house of Merapi’s gatekeeper Mbah (grandfather) Marijan, adding “they were burnt by heat clouds”.
The house of Marijan, the traditional spiritual keeper of the mountain, is about four kilometres (2.5 miles) from the peak, in Sleman district.
“There are likely to be more victims as the terrain is difficult, roads are damaged and trees uprooted, it’s dark and the condition of the volcano is still unstable,” Taufiq added.
Local TV station MetroTV reported that 15 bodies were found.
Earlier, a doctor at Muntilan hospital, Sasongko, confirmed the death of a baby, telling MetroTV: “The baby had severe breathing difficulties from inhaling volcanic materials and we could not help it.”
Television footage showed thousands of people fleeing in panic, some covered in white ash, as officials with loudhailers tried to help them escape the area.
Authorities had put an area 10 kilometres (six miles) around the crater of Mount Merapi on red alert Monday, ordering 19,000 people to flee.
Volcanologist Surono said the eruption was bigger than an eruption in 2006, which killed two people.
Before the latest eruption officials said nearly 15,000 people had ignored evacuation orders despite several minor blasts that sent lava spewing down Merapi’s southern slopes.
Volcanologists have warned that Merapi, a 2,914-metre (9,616-foot) peak around 25 kilometres north of the cultural capital of Yogyakarta, currently has more energy than before the June 2006 blast.
Its deadliest eruption occurred in 1930 when more than 1,300 people were killed. Heat clouds from another eruption in 1994 killed more than 60 people.