Mount Tongariro latest

VOLCANIC ALERT BULLETIN: TONG – 2013/04
TONGARIRO VOLCANO
Volcanic Alert Level: 1 (no change)
Aviation Colour Code: Green (no change)
3 pm Tuesday 6th August 2013

Very small earthquakes beneath Tongariro; no change to Volcanic Alert Level or Aviation Colour Code.

During the past two weeks, the GeoNet seismic network has detected a few very small earthquakes beneath Mt Tongariro. These events have been recorded only on a few seismic stations 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.

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 2012 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.

Te Maari has had no eruptive activity since an explosion on 21 November 2012 although an eruption could still occur with little or no warning.

Through the GeoNet project, GNS Science continues to monitor Tongariro for any new earthquake activity or changes in volcanic gas concentrations, and keeps a close watch for any visible changes.

Background
Aviation Colour Codes are based on four colours and are intended for quick reference only in the international civil aviation community. Code Green indicates that a volcano has no eruptive activity.

The Volcanic Alert Level ranges from 0 to 5 and defines the current status at a volcano. Level 1 indicates volcanic unrest, with departures from background level.

The GeoNet project is funded by EQC and provides monitoring for all of New Zealand’s volcanoes.
http://www.geonet.org.nz/volcano/
http://www.gns.cri.nz/Home/Our-Science/Natural-Hazards/Recent-Events/Tongariro

VOLCANIC ALERT BULLETIN: TONG – 2013/03
TONGARIRO VOLCANO
Volcanic Alert Level: 1 (no change)
Aviation Colour Code: Green (lowered from Yellow)

2.30 pm Monday 25 March 2013

Tongariro remains quiet, Aviation Colour Code Lowered to Green
As a result of a continuing quiet period at Tongariro, GNS Science has lowered the Aviation Colour Code to Green from Yellow. Aviation Colour Code are used as a guidelines for international civil aviation, and reflects the potential impact of volcanic eruptions on that industry.

The Te Maari area on Tongariro continues to produce steam and volcanic gases and an eruption could still occur with little or no warning. The Volcanic Alert Level therefore remains at 1.

Last week numerous reports were received regarding potential eruptions from Te Maari, but these reflected weather conditions and natural variations in steam and gas emissions. GNS volcanologist Michael Rosenberg said, “As soon as the weather gives a good steam plume the phones start ringing. We are all going to have to get used to steaming at Tongariro. It might continue for years and vary substantially from time to time, even if we get no more eruptions.”

Tongariro has had no eruptive activity since an explosion on 21 November 2012. Earthquake activity has been negligible since before the November 2012 eruption and the flux of volcanic gases has remained relatively low and stable for several months.

Through the GeoNet project GNS Science continues to monitor Tongariro for any earthquake activity, makes frequent measurements of volcanic gas concentrations and keeps a close watch for any visible changes.

Background
Aviation Colour Codes are based on four colours and are intended for quick reference only in the international civil aviation community. Code Green indicates that a volcano has no eruptive activity.

The Volcanic Alert Level ranges from 0 to 5 and defines the current status at a volcano. Level 1 indicates volcanic unrest, with departures from background levels.

The GeoNet project is funded by EQC and provides monitoring for all of New Zealand’s volcanoes.
http://www.geonet.org.nz/volcano/
http://www.gns.cri.nz/Home/Our-Science/Natural-Hazards/Recent-Events/Tongariro

Te Maari 21/11/2012 eruption column taken from Emerald Lakes. Photo Brad Scott.

Te Maari 21/11/2012 eruption column taken from Emerald Lakes. Photo Brad Scott, GNS Science.

VOLCANIC ALERT BULLETIN: TONG – 2013/2
Tongariro Volcano
Volcanic Alert Level: 1 (unchanged)
Aviation Colour Code: Yellow (unchanged)

9 am Thursday 14 February 2013

GNS Science says that activity at Tongariro remains low, but steam and gas plumes from the Te Maari area are always present.

Tongariro has had no eruptive activity since the explosion on 21 November 2012. Earthquake activity has been negligible since before the November 2012 eruption and the flux of volcanic gases has remained relatively stable for several months.

GNS volcanologist Brad Scott said, “After the eruption in November 2012 we had to consider the possibility that Tongariro might have entered an eruptive episode similar to one that occurred in the 1890s. However, we do not know if further eruptions will occur or if the Te Maari crater area will just quietly discharge steam for several years. If further eruptions do occur we have to expect that they might have little or no warning.”

GNS Science head volcanologist Gill Jolly said, “It is difficult to be certain what will happen over the next few months, but we expect that eruptions substantially larger than that in August 2012 should give us some warning signs.”

In recent weeks GNS Science have received several reports describing unusually strong steam emission from the Te Maari crater area. Some of these can be attributed to weather conditions but others probably reflect natural variability in the steam and gas emission rates.

GNS Science continues to closely monitor Tongariro through the GeoNet project.

VOLCANIC ALERT BULLETIN: TONG – 2013/1
Tongariro Volcano
Volcanic Alert Level 1 (unchanged)
Aviation Colour Code: Yellow (unchanged)

3pm Monday, 14th January 2013

Mt Tongariro update: Unrest and volcanic gas emissions continue.

Te Maari craters at Mount Tongariro, the site of eruptions in August and November 2012, continue to be active with continuous emissions of steam and volcanic gas. Emission of a steam and gas plume has been a continuous feature of the mountain since the August 2012 eruption. The gas is coming from a large fumarole and crack, in a cliff just east of the Upper Te Maari crater. The main Upper Te Maari crater is also discharging gas but at a lesser rate. Fumaroles associated with a fissure farther to the east have declined and are no longer easily visible.

Volcanic gas from the plume may continue to be smelt in areas downwind of the volcano. GNS Science volcanologists will be making gas measurements at the next available opportunity to compare to those made at the end of December 2012, however recent visual observations show that the emissions are on-going and sustained. Observers of the mountain may notice that emissions appear to be stronger on some days than others, which is due to a combination of variability in the degassing rate and atmospheric conditions which make the plume more visible on some days. GNS head volcanologist Gill Jolly said “gas and steam emissions from the volcano will continue to be a feature of the mountain for several years to come.”

Aerial observations at the end of 2012 showed that a large amount of material had in-filled the Upper Te Maari crater as part of the November 21st 2012 eruption, however the main shape of the crater had not changed.

Seismicity has remained relatively low with no earthquakes yet recorded beneath the mountain in 2013.

Tongariro continues to be in a heightened state of unrest and eruptions could occur with little or no precursors.

GNS Science through the GeoNet project is continuing to closely monitor the volcano.

The Volcano Alert Level remains at 1 and the Aviation Colour Code remains at Yellow.

VOLCANIC ALERT BULLETIN: TONG – 2012/36
TONGARIRO VOLCANO
Volcanic Alert Level: 1 (no change)
Aviation Colour Code: Yellow (no change)

4.45 pm Tuesday 11 December 2012

Prominent gas discharge at Tongariro, but no eruptive activity

Despite continued gas discharge, that has been very noticeable over the last few days, Tongariro has not erupted since the explosion on 21 November. However, because of the current volcanic unrest a substantial possibility of further eruptions remains over the next few months.

GNS volcanologist Brad Scott said, “After the second eruption in November we now have to consider the possibility that Tongariro might have entered an eruptive episode and this unrest could continue for several months. Within an episode Tongariro might quietly discharge steam most of the time, but occassionally have small eruptions with little or no warning. There was a similar episode of activity in the 1890s”.

GNS head volcanologist Gill Jolly said, “There is still a lot we don't know about the recent activity and this means it is difficult to be certain what will happen over the next few months. Unfortunately with active volcanoes nothing is black and white and our best assessments still have a lot of uncertainty”.

“What we can say is that eruptions substantially larger than that on August 6 should give us some warning signs and at the moment we don't see any such signs ”, said Dr Jolly.

In recent days GNS Science have received several reports of possible eruptions, but these have been normal steam discharge coupled with fine weather and light winds making for a prominent steam and gas plume.

There has been only minor seismic activity at Tongariro since 21 November, and no volcanic gas measurements last week due to poor weather and high winds.

Gas may continue to be smelt downwind from Tongariro and be a minor irritant.

GNS Science continues to closely monitor Tongariro through the GeoNet project.

26 November 2012, 1:30pm. Eruption update: Activity low at Tongariro;

Volcanic Alert Level changed to Level 1;
Aviation Colour Code remains at Yellow. Read more.

No further volcanic activity has occurred since the eruption on 21 November 2012. Gas flux has decreased and seismic activity remains low. GNS Science continues to closely monitor the situation.

GNS Science has now lowered the Volcanic Alert Level from Level 2 to Level 1. This is based on the lack of further eruptions, no volcanic ash in the plume, decrease in gas output and continuing minor seismic activity. Conditions are now similar to before the November 21 eruption. The Aviation Colour Code remains at Yellow”.

While we were able to recognise the onset of the state of unrest at Te Maari, we cannot recognise useful precursors to eruptions like last week. Over the next week, the scenario considered most likely is that there may be further eruptions and these could occur with no warning. Despite the reduced gas output a gas odour can expected downwind from Tongariro.

21 November 2012 Eruption

Tongariro eruption time series.pdf (1.45 MB)

After reviewing monitoring data, videos and images for the 21 November 2012 eruption at Tongariro, GNS Science confirms that the eruption lasted approx 5 min, with an ash column and plume being ejected 3-4 km above the Upper Te Maari crater.

The eruption was recorded by GeoNet’s webcam. Watch a video of the eruption.

The point of origin of the 21 November 2012 eruption was similar to that from the eruption August 6, 2012. During the recent eruption, two small pyroclastic density currents were produced at the base of the column, to the West and North of the crater, and reached a limited distance of a few hundred meters downslope. These pyroclastic density currents are a mixture of ash, volcanic gas and atmospheric air flowing horizontally and being driven by gravity. Scientists believe that these were produced by part of the ash column not being energetic enough to rise, causing it to collapsing at the base and flow downhill. There is no evidence at this stage of big blocks having been ejected far from the crater during the eruption.

From the preliminary examination of ash, GNS Science volcanologist Michael Rosenberg reported that “we haven't found any evidence yet of magma having reached the surface during the eruption”. More ash sampling and analyses by New Zealand volcanologists are planned or already underway.

There was no observed warning immeditately prior to yesterday’s eruption. Future eruptions could also occur with little or no warning.

Contact
Brad Scott, Nico Fournier. Phone 07-374-8211