The submarine volcano East Epi, located in Vanuatu in the Pacific, erupted on Wednesday, throwing ash up to 100 meters high.
Authorities advised ships and aircraft to avoid the area.
“We ask the local population to be careful of possible strong explosions, because the eruptions are still in progress,” Ricardo William, a volcano specialist with the Vanuatu Department of Meteorology and Geological Hazards, told AFP.
A security perimeter of 10 km has been established around the underwater volcano, which is 68 km north of Port Vila, the capital of this Pacific state.
Steam had been reported above the site, then the volcano had started throwing ash on Wednesday morning.
Volcanic activity began shortly before 8 a.m. local time (2100 GMT Tuesday), according to the local meteorology department.
Government official Philip Dick told AFP the ground began to shake and smoke was visible above the site in the early hours.
“Then the explosions started – there is still a bad smell of sulfur in the nearby villages,” he added.
Authorities raised the volcanic alert to the first level (out of five), indicating “minor unrest”.
Residents of the nearby islands of Epi and Tongoa have been told to avoid the coast.
The ministry said in a statement that although the tsunami warning center located in Alaska (USA) did not detect any activity in the Vanuatu region, “such eruptions have the potential to create tsunami waves “.
Vanuatu is in an area of high seismic activity, also called the “Pacific Ring of Fire”, where tectonic plates meet.