Earthquakes at Tongariro 'of interest'

02:06, Aug 07 2013

A number of ''very small'' earthquakes beneath Mt Tongariro could be a sign changes are occuring inside the volcano.

These small tremors have been recorded only on a few seismic stations over the past two weeks and are too small to be precisely located.

GNS Science said the earthquakes could simply be part of the background unrest typical of most active volcanoes.

The earthquakes are of interest at this time because there have been so few at Tongariro since November 2012 and potentially could signal changes occurring inside the volcano.

Today is 12 months to the day since Tongariro erupted for the first time in 115 years leaving a coating of ash across the Central Plateau and raining rocks on the mountain's slopes.


A smaller eruption occurred on November 21 after which the mountain continued to discharge gas for several months.

GNS said the amounts of carbon dioxide and sulphur gases emitted from Tongariro have remained at low levels since the start of this year and are about half the amount produced after the November explosion.

These conditions, and the small number and small size of recent earthquakes are not sufficient to alter the unrest status of the volcano and GNS Science has not changed the Volcanic Alert Level from 1, or the Aviation Colour Code from Green.

An eruption could still occur with little or no warning GNS said.

Manawatu Standard