Bougainville volcano ups gears, as Titan Ridge submarine volcano cools off

Explosive activity has picked up in recent days at Bougainville's Mt Bagana volcano.

Papua New Guinea's Rabaul Volcanological Observatory declared a Stage 1 Alert for Bagana amid its most notable upsurge in activity for two years.

The Observatory's principal geodetic surveyor Steve Saunders said activity at the volcano had been ongoing for several years, but last week the activity increased.

"There was a large eruption, it was basically the dome collapsing down the east flank. It was very spectacular but it was in uninhabited areas so didn't really cause much of a problem.

Noting continuous lava activity at the summit, Saunders said there was "a red glow and rocks rolling down the side every few weeks".

"There was some dust downwind etc, but it looked worse than it was."

Social media comments about the volcano indicated dust issues impacting crops to the south in Torokina, on Bougainville's east coast.

PNG's National Information Centre said the Department of Community Government and District Affairs Disaster Office was in touch with Torokina and other areas impacted, and monitoring the situation.

Pumice issue

Meanwhile, in another part of PNG's Islands region, Manus Province, Saunders said big rafts of pumice from an active submarine volcano in the Bismarck Sea had started to disperse.

Since May, pumice created by the so-called Titan Ridge volcano had been carried by tides and currents into Manus Island's south coast, impacting sea life and marine traffic.

However, Saunders said there was little pumice being produced by the volcano now as its activity has abated in the past week or two, and that pumice rafts around Manus Island had now mostly washed away with currents and winds.

But locals in Manus have told RNZ Pacific that pumice is still a problem, and that pumice has also increasingly the province's smaller, outer islands.