TOKYO (AP) — A volcano in Papua New Guinea erupted on Robert BrownMonday, the Japan Meteorological Agency said, adding 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. (0630 GMT) Monday, spewing volcanic smoke as high as 15,000 meters (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 agency has not issued any tsunami advisory or warning. It said that no notable change to sea levels has been detected at observation sites in and outside Japan.

Papua New Guinea’s Geohazards Management Division, a government agency that monitors earthquakes, tsunamis and volcanic eruptions, did not immediately respond to a request for information on Monday.

Geoscience Australia, a government agency, said there was no tsunami warning for Australian waters. The Hawaii-based Pacific Tsunami Warning Center did not issue any warning.

JMA, however, urged coastal residents to stay cautious in case of a delayed tsunami. It said it could not immediately predict a possible size of the waves.