TOKYO — A volcano in Papua New Guinea erupted on Monday, and the Japan Meteorological Agency (JMA) said it was assessing a possible risk of a tsunami for Japanese coasts.

Mount Ulawun on the island of New Britain in Papua New Guinea erupted at around 3:30 p.m. Monday, spewing volcanic smoke as high as 50,000 feet, the agency said, quoting the Volcanic Ash Advisory Center in Darwin, Australia.

The agency said it was assessing a possible impact, including the risk of a tsunami approaching Japan later Monday. First tsunami waves could reach Izu and Ogasawara islands about three hours after the shaking caused by the eruption, JMA said.

The eruption is expected to continue indefinitely and the volcano’s risk level was raised to the highest stage of four, Papua New Guinea’s Geohazards Management Division said.

Ulawun is one of the most active volcanoes in Papua New Guinea, which sits on the Pacific “Ring of Fire,” the arc of seismic faults around the Pacific Ocean where much of the world’s earthquake and volcanic activity occurs. Ulawun has repeatedly erupted since 1700s, and had a last major eruption in 2019.