Mt Ruapehu volcanic unrest continues

Source: 1News

Scientists are continuing to keep an eye on Mt Ruapehu as its volcanic tremors continue.

The temperature of the crater lake on the mountain has dropped over the past week and tremor levels have "generally declined", GeoNet volcanologist Yannik Behr said.

He wrote that the temperature of the lake had dropped from a peak of 41C on May 8 to 30C on Tuesday.

"The heavy rainfall last week caused a temporary rise in lake level and a drop in lake temperature. The lake level has now returned to the normal pre-rainfall level, while the lake continues to cool indicating a general decrease in the amount of heat entering the lake."

But, tremor levels continued to be "variable", he added.

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Behr said the most likely outcome within the next four weeks is "minor eruptive activity" confined to the lake basin, or no eruption.

He said minor eruptions may generate lahars - dangerous volcanic mudflows - in the Whangaehu River.

Behr said sulphur dioxide gas emissions from relatively shallow magma suggested the volcano "is still at a heightened level of unrest".

Thus, the Volcanic Alert Level remains at 2, he said.

"The chance of a prolonged eruptive episode or a larger eruption… is higher than it was two months ago, but within the next four weeks remains very unlikely. Such an eruption would most likely only follow a sequence of smaller eruptions.

"Due to the heightened volcanic unrest, GNS Science staff are carrying out more frequent aerial observations and gas measurements when weather conditions are suitable."