The eruption of Hunga-Tonga-Hunga-Ha’apai has triggered tsunami waves in Tonga

Fallout from the massive eruption of underground volcano Hunga Tonga-Hunga Haʻapai on Saturday evening continues with the impact yet to be determined.

The huge underwater volcanic eruption caused waves of more than a metre to crash into Tonga.

Tonga is reportedly covered in ash and experiencing power and internet blackouts making it difficult to define any reported death or casualties.

According to Tonga Geological Services, plumes of smoke and gas have poured from the volcano reaching up to 20km into the sky.

The eruption of the Hunga Tonga-Hunga Haʻapai volcano was said to be heard not only in the South Pacific but as far as the US who warned of strong waves and coastal flooding.

Japan also advised people on their Pacific coastlines to take refuge from the shoreline as a precautionary measure, further warning of waves as high as three metres.

Local residents described the eruption as like a bomb going off.

The eruption was also heard more than 800km away in Fiji, according to officials in the capital, Suva with the government issuing a tsunami warning, opening evacuation centres for people in coastal areas. Local island Vanuatu also issued a similar warning.

Volcanologist Prof Shane Cronin from the University of Auckland said the eruption was one f the largest seen in the last 30 years on Tonga.

"This is a pretty big event - it's one of the more significant eruptions of the last decade at least," he told the BBC.

"The most remarkable thing about it is how rapidly and violently it's spread. This one was larger, had a much wider lateral spread, much more ash was produced. I expect there to be many centimetres of ash that have been deposited on Tonga."

Australia issued a tsunami warning for parts of Australia's east coast and Tasmania, with a spokesperson for the Australian government saying Scott Morrison and the minister for foreign affairs were monitoring the situation and ready to provide support on request.