The likelihood of Mt Ruapehu erupting has increased, GNS
Duty volcanologist Steven Sherburn said changes in
measurements at Ruapehu over the last few weeks indicate
eruptions are "more likely over the next weeks to months".
"We are monitoring Ruapehu closely, but it often does not
give any immediate warning that it is going to erupt," Dr
"We think that the temperature a few hundred metres beneath
Crater Lake is about 800 degrees Celsius, but the lake itself
is only about 20 degrees Celsius.
"This suggests the vent is partly blocked which may be
leading to a pressure build-up beneath Crater Lake. A sudden
release of the pressure may lead to an eruption."
As a result, the Aviation Colour Code has increased from
Green to Yellow. Code Yellow indicates a volcano is
experiencing signs of elevated unrest above known background
GNS said small earthquakes have been occurring about 5km
beneath the summit area of Ruapehu since late October, but
these may not be directly related to the high temperatures
beneath Crater Lake because they are much deeper.
A build-up of pressure beneath Crater Lake is thought to have
caused the 2007 eruption and a smaller eruption in 2006.
- Paul Harper of nzherald.co.nz