Acid rain and eruption prompts warning in Tonga

Hunga Tonga and Hunga Ha'apai are two close volcanic islands in Tonga. Photo / RNZ

Acid rain from a large volcanic eruption in Tonga continues to threaten water tanks, as huge plumes of 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 smothered the whole of Tonga.

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

"This morning it's still continuing to emit gas and vapour into the atmosphere. This morning you can still see the white clouds, it is probably about 16km high."

Matangi Tonga reported the eruption was at Hunga Ha'apai island, but a bright white gas cloud could be seen from Tonga's capital Nuku'alofa, 65km north, and bursts of lightning played through the cloud on Tuesday evening.

People in Tonga were last night told to protect water tanks from possible acidic rainfall until the eruption ends.

Tonga Geological Services said residents should remove guttering systems from rainwater tank storage until the eruption finishes. These should not be reinstalled until after the next rainfall, to reduce the risk of contamination.

Symptoms of exposure to acid rain are itchiness and skin irritation, and blurry discoloured vision. If skin or eyes are exposed to acid rain people should see a doctor.

Air New Zealand cancelled a flight from Auckland to Tonga that was due to fly yesterday, because of concerns about the ash cloud.

The flight included the funeral cortege for Tonga's Deputy Prime Minister, the late Lord Ma'afu. Matangi Tonga said the funeral programme was postponed as a result.

In 2015, Tongan government officials said eruptions at Hunga Ha'apai had formed a new island more than a kilometre long, joined to the existing island. It has reportedly become a home for plants and birds.