A magnitude 6.0 undersea earthquake shook the eastern side of Indonesia on Sunday morning, injuring 29 people, including two in critical condition.

The quake struck 15 kilometres north of the Poso district in the Central Sulawesi province, according to the US Geological Survey, and was followed by at least 15 aftershocks.

No tsunami warning was issued by Indonesian authorities.

Indonesia’s National Disaster Mitigation Agency said most of the injured had been taken to a nearby hospital to receive treatment. Most of them were from a group of people attending Sunday morning service at a church in the impacted area, said National Disaster Mitigation Agency spokesperson Abdul Muhari.

“Amateur videos showing structural damage to the church have been circulating. Poso Disaster Mitigation Agency continues to conduct rapid assessments in the field to determine the initial impact of the earthquake,” Muhari said.

Indonesia, a vast archipelago of more than 270 million people, is frequently struck by earthquakes, volcanic eruptions and tsunamis because of its location on the ‘Ring of Fire’, an arc of volcanoes and fault lines in the Pacific Basin.

In 2022, a magnitude 5.6 earthquake killed at least 602 people in West Java’s Cianjur city, the deadliest disaster one in Indonesia since a 2018 tremor and tsunami in Sulawesi, which killed more than 4,300 people.

In 2004, an extremely powerful Indian Ocean quake set off a tsunami that killed more than 230,000 people in a dozen countries, most of them in Indonesia’s Aceh province.