Acid rain from a large volcanic eruption in Tonga continues to threaten water tanks, and ash threatens air quality as huge plumes of gas and dust are thrust into the air.

Tonga’s head geologist Taaniela Kula told RNZ Pacific the “huge” eruption began on Monday morning, and by the afternoon ash had dusted the whole of Tonga.

He said ash clouds had since drifted north creating a spectacular sight, and leading to warnings.

He said there is no knowing for certain when the volcano will settle, but expects it to continue for at least another week.

People in Tonga have been told to protect water tanks from possible acidic rainfall, until the eruption ends.