Volcanic Alert Bulletin TON-2012/33 - Tongariro Volcano

23 November 2012, 12:00 pm - Eruption update: Activity still low at Tongariro; Volcanic Alert Level remains at Level 2; Aviation Colour Code changed to Yellow

Activity recorded at Tongariro remains at a low level. There is still a substantial amount of gas emitted but no ash. Gas smell may therefore be expected downwind from Tongariro.

GNS Science lowered the Aviation Colour Code to Yellow from Orange due to the absence of ash being emitted from the volcano since the eruption. The Volcanic Alert Level remains at 2 and the volcano may erupt at any time with little or no warning.

This morning, GNS Science installed some additional equipment at an existing monitoring site, 3 km north-west of the active crater. A “gas flight” is also planned as soon as possible when weather allows, with the intent of measuring the amount of gas coming out from the volcano.

The Aviation Colour Code is now at Yellow. The Volcanic Alert Level remains at 2. GNS Science continues to closely monitor the situation.

Background

GNS Science uses a range of tools to monitor volcanoes. Seismometers record earthquakes, GPS stations record ground swelling. Acoustics sensors record air-waves such as those produced by an eruption. An additional acoustic sensor was installed on Tongariro this morning.

GNS Science also carries out “gas flights” to quantify how much gas is emitted from volcanoes. Gas sensors are installed inside a small plane and scientists fly around the gas plume to make the measurements. Gas flights are dependent on weather conditions (e.g., presence of clouds, wind direction). Such conditions are not favorable at Tongariro at the moment.

The Volcanic Alert Level ranges from 0 to 5 and defines the current status at a volcano. Level 2 indicates that a minor eruption has occurred.

Aviation Colour Codes are based on four colours and are intended for quick reference only in the international civil aviation community. Code Yellow indicates that volcanic activity has decreased significantly but continues to be closely monitored.

Brad Scott, Nico Fournier
Volcanologists

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