Tongariro volcano alert level up after series of quakes

THE volcanic alert level for Mt Tongariro has been upgraded following a series of earthquakes. GNS Science has recorded 20 earthquakes with a magnitude of 2.5 or less under the mountain since July 13.

Typically, there were only two quakes detected under the central North Island mountain each year, GNS volcanologist Brad Scott said.

Seismic activity indicating un- rest was last detected at Tongariro during 2001.

GNS had increased monitoring of the mountain and upgraded the volcanic alert level from zero to one yesterday.

The highest level is five and indicates a large hazardous eruption in progress.

Mr Scott said the activity was not life threatening, but they were taking a precautionary approach.

The volcano last erupted more than 100 years ago.

‘‘That’s a long time ago, but it has erupted so it could erupt again. We’ve got no data that says, ‘Hey, I want to erupt.’ It’s just, ‘Hey I’m restless and rolling over in my bed.’ ’’

Trampers in Tongariro National Park and residents in nearby towns should not be alarmed, Mr Scott said.

Mt Ruapehu and White Island each have an alert level of one.

The aviation colour code was also upgraded for the airspace near Mt Tongariro from green to yellow, meaning the volcano is experiencing signs of elevated unrest above known background levels.

This month’s quakes were clustered in a zone between the Emerald Crater and Te Mari craters at a depth of between two and seven kilometres, Mr Scott said.

To better understand the significance of the quakes, GNS was planning to put portable seismic recorders around the epicentres.