A 7.1-magnitude earthquake struck off Indonesia’s Sumatra today, the US Geological Survey (USGS) said, prompting islanders to seek shelter on higher ground until a tsunami warning is lifted.

No casualties or material damage have been reported so far.

“The earthquake was so possible that it was difficult for us to get up and go out,” said Patrice Sanene, 34, a resident of Siberut, the largest of the Medavai islands. “We had difficulty getting out of the house, we had to grab onto walls.”

“It was the strongest earthquake (…) this year. I thought there was going to be a tsunami. Thank God we didn’t have a tsunami,” he added.

The Indonesian Geophysical Agency (BMKG) issued an emergency tsunami warning, which subsided after about two hours.

Indonesia experiences intense seismic and volcanic activity due to its location on the Pacific Ocean’s “ring of fire,” where tectonic plates collide.

The deadliest earthquake in Indonesia occurred off Sumatra on December 26, 2004, when more than 230,000 people died not only in the country itself, but also in Sri Lanka, India and Thailand, where giant sea seismic waves hit . The tsunami was more than 30 meters high when it hit the coastline of Banda Aceh, in northern Sumatra. The earthquake that caused it had a magnitude of 9.1.