At least 38 people have died after a 7.7-magnitude earthquake struck off the coast of Indonesia’s Flores Island early Saturday, authorities said.

The quake took place just before 5 a.m. and according to the U.S. Geological Survey was centered in waters north of the island, some 1,000 miles east of the capital Jakarta. Indonesia sits on the Pacific “Ring of Fire” and is a hot spot for tectonic activity due to the convergence of the Australian and Sunda tectonic plates.