Indonesian authorities say they have no reports of casualties following a major 7.7-magnitude earthquake off the west coast of Sumatra.

The quake struck the Simeulue region around 205 kilometres from the city of Sibolga shortly before 5:15am (local time) today at a depth of about 46 kilometres.

Witnesses had reported power blackouts and panic on Simeulue island, but Aceh’s governor says there are no reports of casualties or damage in the province.

“I am on the coast now. Some people had gone to take refuge on higher ground but now they have returned to their homes,” governor Irwandi Yusuf told Metro TV.

Indonesian police say they have no reports of significant damage on Simeulue.

The Pacific Tsunami Warning Centre said there was no danger of a significant tsunami and said it was cancelling a tsunami watch issued just after the quake.

Earlier, tsunami waves up to 14 centimetres were recorded at Teluk Dalam on Nias Island, south west of Sibolga.

Across the Andaman Sea, Thailand cancelled a tsunami alert which had been issued after the earthquake hit.

Indonesia’s quake agency says there have been at least three aftershocks off Aceh.

Witnesses speak

Residents of Banda Aceh said they felt the earth shaking powerfully for about a minute and many fled their homes or piled onto motorcycles to head inland in fear of a destructive tsunami.

“People panicked and ran out of the house. It lasted almost a minute,” an AFP reporter in Banda Aceh said.

“I saw a lot of people who live close to the sea using motorcycles to drive inland.”

Jeffry, who manages a hotel in the northern Sumatran city of Medan, says the quake was felt twice and each time it lasted for about four minutes.

“It lasted around four minutes. It happened two times, so at about 5:15am and 5:30am,” he said.

He says it was felt across the city.

“Things not moving, we can feel it. It’s not strong, just shaking a little bit,” he said.

“At present we have checked all over the area. We haven’t found any damage of the building. The whole city also felt the same thing.”

Jeffry says people in the region are still trying to work out the extent of damage following the quake.

He says many people working at the hotel in Medan have relatives in neighbouring Aceh, where he says there are reports of power outages.

“We have checked through the internet. For the time being we only receive information from Medan. We haven’t heard anything,” he said.

Ring of fire

The US Geological Survey originally measured the quake at 7.6 before upgrading it to 7.8 and then downgrading it to 7.7.

The city of Sibolga, home to almost 80,000 people, serves as the launching point for tourists heading to the international surf hub centred on Nias.

More than 600,000 people live on Nias and the surrounding islands.

Both Nias and Sibolga were hit hard by the 2004 Boxing Day tsunami and the March 2005 tsunami.

Hundreds were killed and the quakes and following tsunamis changed the coastline of Nias.

Indonesia sits in the Pacific ring of fire, an area prone to earthquakes because of the constant movement of volcanic belts and plates.

In December 2004 a magnitude 9.15 quake off the coast of Sumatra’s Aceh province triggered an Indian Ocean tsunami that killed about 226,000 people in Indonesia, Sri Lanka, India, Thailand and nine other countries.

In March 2005 about 1,300 people were killed after an 8.7-magnitude quake struck off the coast of the Indonesian island of Nias, west of Sumatra.

A 7.6-magnitude quake in West Sumatra province in September last year killed about 1,000 people, according to official figures.