The public has been advised to stay away from the coastal areas.
There was a major eruption at Hunga Tonga Hunga Ha-apai this afternoon.
Locals reported the eruption lasted about eight minutes and rattling windows and sending ash into the air.
There were sirens warning people to evacuate to higher ground.
Tidal waves crossed the Nuku'alofa shoreline and coastal roads and flooded properties.
RNZ Pacific reports it's dark now in Nuku'alofa and ash is falling and people can see lightning in the ash clouds.
