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Volcanic Alert Bulletin RUA 2016/02:
10:15am Tuesday 3 May 2016; Ruapehu Vol
cano 

Alert Status:
Volcanic Alert Level
 remains Level 1
Aviation Colour Code
remains Green

The volcanic earthquake swarm which intensified at Mt Ruapehu around April 25-26 is now declining and the Crater Lake temperature has peaked at 42 °C. A short period of moderate volcanic tremor was recorded on Monday afternoon.  Mt Ruapehu remains at Volcanic Alert Level 1 (Minor volcanic unrest).

Since April 25-26 we have been recording a volcanic earthquake swarm beneath the Crater Lake of Mt Ruapehu. The number of events and size has now declined. Swarms of volcanic earthquakes like these are uncommon on Ruapehu in recent years. Seismic activity at Mt Ruapehu is usually dominated by volcanic tremor. A period of moderate volcanic tremor lasting about an hour was recorded from 13:10h on Monday 2 May.

The temperature of the Crater Lake has been rising and since mid-April 2016. It has risen from 25 °C to 42 °C and is now equal to the highest recorded since 2011. The temperature appears to have reached a maximum and no increase has been recorded in the last day.

Currently we are uncertain of the implications of the recent observations. However at this time these changes at Ruapehu are not considered insufficient to change the volcanic alert level. The volcanic alert level for Mt Ruapehu remains at Volcanic Alert Level 1 (Minor volcanic unrest).

GNS Science volcanologists continue to closely monitor Ruapehu through the GeoNet project.

 

Brad Scott
Duty Volcanologist

Media Contact:
07 3748211

Volcanic Alert Bulletin WI 2016/05
1:00 pm Monday 2 May 2016  

Alert Status: White Island Volcano

Volcanic Alert Level remains Level 2

Aviation Colour Code changed from Orange to Yellow 

The Aviation Colour Code has been lowered from Orange to Yellow. The Volcanic Alert Level remains at Level 2. Heightened volcanic unrest continues at White Island (Whakaari). No eruptions have occurred since April 27. Gas output is slightly elevated but within the range of recent measurements. Seismic activity remains low.

Visual and seismic observations confirm no further eruptive activity has occurred at White Island (Whakaari). During an aerial inspection on Friday the location of the vent that erupted on Wednesday evening was confirmed.

Remote gas measurements confirm no significant change in the long-term gas output from the volcano. Volcano earthquake activity remains low.

There is currently no indication that activity is either increasing or decreasing at White Island. The heightened state of volcanic unrest remains (Volcanic Alert Level 2). GNS Science volcanologists are continuing to monitor the volcano and further bulletins will be released as required.

 

Brad Scott
Duty Volcanologist

Media Contact:
07 3748211

 

Volcanic Alert Bulletin WI 2016/04
10:45 am Saturday 30 April 2016; White Island Volcano

Alert Status:
Volcanic Alert Level
 remains Level 2
Aviation Colour Code
remains Orange

Heightened volcanic unrest continues at White Island (Whakaari). During an aerial inspection on Friday the site of Wednesday’s eruption was seen for the first time; a new crater has formed in the north east corner of the 1978/90 Crater Complex.  Gas output is slightly elevated but well within the range of recent measurements. Preliminary analysis of the eruption deposit suggests that no or little new magma (lava) was ejected. Seismic activity remains low. The Volcanic Alert Level remains at Level 2.

During an aerial inspection on Friday to measure the gas output and photograph the active crater area it was possible to confirm the location of the vent that erupted on Wednesday evening. A new crater has formed in the north-east corner of the 1978/90 Crater Complex.  No vent was visible in this area before Wednesday. Significant collapse has occurred around the area and post-eruption landsliding is also present. Hot translucent gas has been emitted from the new vent.

The gas measurements confirm no significant change in the long-term gas output from the volcano. Volcano earthquake activity remains low.

Laboratory analysis of the eruption deposit collected from the web camera site on the north rim has confirmed that most of the ash is strongly hydrothermally altered old rock material. No evidence of new, juvenile magma was found. This suggests that no new lava material has been erupted and that the eruption was likely driven by steam and gas, like the eruptions in 2012 and 2013.

There is currently no indication that activity is either increasing or decreasing at White Island. The heightened state of volcanic unrest remains (Volcanic Alert Level 2). GNS Science volcanologists are continuing to monitor the volcano and further bulletins will be released as required.

Agnes Mazot
Duty Volcanologist

 

Media Contact:

Brad Scott
Volcanologist

Phone 07 3748211

 

Volcanic Alert Bulletin RUA 2016/01:
3:30pm Friday 29 April 2016; Ruapehu Vol
cano 

Alert Status:
Volcanic Alert Level
 remains Level 1
Aviation Colour Code
remains Green

Over the last few days there has been a volcanic earthquake swarm at Mt Ruapehu. The Crater Lake temperature is now 40 °C. Mt Ruapehu remains at Volcanic Alert Level 1 (Minor volcanic unrest).

Since April 26 we have been recording a volcanic earthquake swarm beneath the Crater Lake of Mt Ruapehu. Swarms of volcanic earthquakes like these are uncommon on Ruapehu in recent years. Seismic activity at Mt Ruapehu is usually dominated by volcanic tremor.

The temperature of the Crater Lake has been rising since late 2015 and since mid-April 2016 the Crater Lake temperature has risen from 25 °C to 40 °C. Similar temperatures and rate of temperature increase were observed in March 2011, April 2014 and February 2015.

We have not noted any changes in other monitored parameters like volcanic gas, lake chemistry or lake overflow.  A gas flight was performed on March 30 and the Crater Lake was sampled on April 14.

Currently we are uncertain of the implications of the recent observations. However at this time these changes at Ruapehu are not considered sufficient to change the Volcanic Alert Level.

GNS Science volcanologists continue to closely monitor Ruapehu through the GeoNet project.

The changes at Mt Ruapehu are not related to the volcanic eruption that occurred at White Island on Wednesday 27 April.

Agnes Mazot
Duty Volcanologist

Media Contact:

Brad Scott
Volcanologist 

phone 07 3748211

 

Volcanic Alert Bulletin WI 2016/03:
6:45pm Thursday 28 April 2016; White Island Vol
cano 

Alert Status:
Volcanic Alert Level
 is lowered to Level 2
Aviation Colour Code
remains Orange

Based on new observations, the Volcanic Alert Level for White Island has been lowered to 2 from 3. This indicates that the volcano is not erupting anymore but remains in a state of moderate to heightened unrest. The Aviation Colour Code remains at Orange.

An eruption occurred at White Island at about 9:50 pm yesterday (Wednesday, 27 April 2016). No further eruptive activity has been observed since yesterday evening. Seismic activity remains low and new gas emission data for today show a SO2 (sulphur dioxide) flux level similar to that prior to the eruption. As a consequence of the continued lack of activity since the eruption on Wednesday evening, the Volcanic Alert Level has been lowered to Level 2.

A more precise time for the eruption, about 9.50 pm, has been inferred from a combination of data from yesterday evening’s seismic activity, a MetService rain radar image, and data from a GPS receiver on the island.

GNS volcanologists flew over White Island this afternoon to assess the impacts of last night’s eruption. A dark-green ash deposit from the eruption covers at least 80% of the floor of Main Crater, and up the sides of the crater wall on both the north and south sides. At a distance of 500 m from the eruption site the ash deposit is about 5 mm thick. The green colour is due to minerals on the ash.

There is currently no indication that activity may be building up at White Island. However, GNS Science staff will not be visiting the main crater floor until further notice due to the heightened state of volcanic unrest. GNS Science volcanologists are continuing to monitor the volcano 24/7 using existing instrumentation on the island and occasional measurements made from safe distance. Further bulletins will be released as required.

Agnes Mazot
Duty Volcanologist

 

Media Contact:
Brad Scott
Volcanologist 

phone 07 3748211


 

See pictures on our Twitter feed.

Volcanic Alert Bulletin WI 2016/02:
11:33am Thursday 28 April 2016; White Island Volcano

Alert Status:
Volcanic Alert Level
raised to 3 
Aviation Colour Code
changed to Orange

An eruption occurred at White Island (Whaakari) sometime between 9:30 – 11:00 pm yesterday (Wednesday, 27 April 2016).

As a consequence of this activity the Volcanic Alert Level is now raised to Level 3 (Minor Volcanic Eruption) and the Aviation Colour Code to Orange.

No eruptive activity has been seen since about 11:00 pm yesterday.

The eruption that occurred Wednesday 27 April was accompanied by a moderately elevated seismic activity. The seismic activity is now back to normal.

The eruption appears to have deposited material over north side of the crater floor and up onto north crater wall.

There is not yet a clear view of crater area visible from cameras.

GNS Science volcanologists are monitoring the volcano and further information will be released as soon as it is available.

 

GNS Science continues to closely monitor all our active volcanoes through the GeoNet project. The Volcanic Alert Level ranges from 0 to 5 and defines the current status at a volcano. Aviation Colour Codes are based on four colours and are intended for reference only in the international civil aviation community.

Contact: Agnes Mazot
Duty Volcanologist
07 3748211

Volcanic Alert Bulletin WI 2016/01:
11:00am Wednesday 27 April 2016; White Island Volcano 

Alert Status:
Volcanic Alert Level
 remains Level 1
Aviation Colour Code
 
remains Green

Routine monitoring of White Island (Whakaari) indicates minor volcanic unrest continues. Over the last couple of weeks GNS scientists have observed a fall of 2 m in the water level of the Crater Lake. However they have not noted any changes in other monitored parameters like the amount of volcanic gas being emitted, fumarole temperatures and the presence of volcanic tremor or earthquakes.  

During a visit last week by GNS volcanologist Brad Scott he was able to confirm the lake level has dropped 2 m in the last 2 weeks. The lake is now at about the same level it was in 2014. The drop in water level of the Crater Lake has revealed several islands or crater outlines and the lake temperature has increased 2 ºC (56-58 ºC) since February.

There has been a small decrease in the temperature of the hottest fumarole (169 to 161 ºC) since February. The SO2 gas output has ranged between 90 and 480 tonnes per day (1.0 to 5.5 kg per second) of gas during the last 5 weeks. These are typical values for White Island.

The level of volcanic tremor continues to vary, but remains below those observed in 2012 when unrest was stronger and small eruptions occurred.

The Volcanic Alert Level remains at Level 1 (minor volcanic unrest). The changes we are seeing presently are consistent with minor volcanic unrest. Typical volcanic unrest hazards like hot ground and gas remain. A range of activity can occur under these conditions with little or no useful warning.

GNS Science is continuing to closely monitor the activity at White Island (and other New Zealand volcanoes) through the GeoNet project.

 

Volcano information: Brad Scott
07 374 8211

 

The GeoNet project is funded by EQC and provides monitoring for all of New Zealand’s volcanoes.

http://www.geonet.org.nz/volcano/info/whiteisland

 

Want to learn more about volcano monitoring?

http://www.gns.cri.nz/Home/Learning/Science-Topics/Volcanoes/Monitoring-Our-Volcanoes

Following the August 2012 eruptions from Te Maari large amounts of volcanic gas were emitted. Sometimes the output of sulphur dioxide (SO2) was over 5-8 kg per second (430-700 tons per day). However with time this decreased and we were not able to measure it from our standard airborne platform. We needed to find a new ground based technology. Based on our experiences from White Island (Whakaari) we chose to go with scanning FLYSPEC, a new version of the miniDOAS that we have at White Island. The new equipment has been installed collaboratively by DOC and GeoNet.  Data from this type of equipment is used by our volcano team to assess the status of the volcano and set the Volcanic Alert Level.

Volcanic gas is derived from the molten material (magma) that drives an eruption, so it is one of the few data that can give us direct information about the magma under an active volcano. The types of gas present and the amounts are very useful. Detecting and measuring gas is not easy. A correlation spectrometer (COSPEC) which was initially designed to measure industrial pollutants, are now routinely used by volcano observatories to measure volcanic gas emissions. The spectrometer is designed to measure the concentration of sulphur dioxide (SO2) in the volcanic plume that is emitted from the volcano. The miniDOAS and FLYSPEC are adaptions of this technology into smaller instruments. They work by analysing the ultraviolet light absorbed by the SO2 molecules in the volcanic plume. Hence we have to install them ‘under the plume’ to get data. The variable wind directions in NZ make this a challenge.

At Te Maari we have installed two scanning FLYSPECS to improve our chances of detecting the SO2 in the volcanic plume. When the local wind is blowing the gas plume over our instruments we are able to get data and work out how much gas is coming from the active vents. We get useable data about 40-50% of the time. Since September 2015 the gas output has dropped below 0.1 kg per second (8.6 tons per day) and is often just at the limits of detection. This is good for Tongariro National Park users as it confirms the volcano is slowly going back to sleep and risk from eruptions has decreased. 

About once a month we plan to make airborne measurements of sulphur dioxide (SO2), carbon dioxide (CO2) and hydrogen sulphide (H2S) outputs from the active volcanoes. The warm humid conditions this summer have challenged us, however last week we made successful flights to White Island (Whaakari), Ruapehu and Ngauruhoe. The gas output hasn’t changed much from any of the volcanoes.

The conditions were really good at Ruapehu and very good data was obtained. There is slight increase in the gas output; however this is well within the usual range seen here. The Crater Lake appeared a light grey colour, calm with no convection or up welling. The lake temperature is currently 23 ºC. The good conditions also allowed for data to be collected at Ngauruhoe. The gas output from Ngauruhoe is very low so if it’s windy or turbulent we often cannot obtain a result. The carbon dioxide (CO2) value shows an increase but we attribute this mostly to the good conditions. They were not so good during the previous flight. 

From the White Island flight we were able to ascertain there has been a decrease in the gas output that ranged 36-55% less than the February result. The wind at the volcano was light and variable; this doesn’t help as the gas is widely dispersed above the volcano and is hard to measure. The airborne data matched the mini DOAS data for the same day. No changes were noted in the Crater Lake.

About our monitoring flights 

We use several techniques to monitor and evaluate the volcanic gas output from our active volcanoes. About once a month we plan to make airborne measurements of sulphur dioxide (SO2), carbon dioxide (CO2) and hydrogen sulphide (H2S) outputs from the volcano.

Two DOAS SO2 gas spectrometers are also installed on White Island and under favourable conditions measure the sulphur dioxide (SO2) gas output. We can get data from them 3-5 days a week.


At GeoNet, much of our information about volcanoes in New Zealand is specific to their current status, specifically, are they or are they not in unrest or erupting. When we raise the Volcanic Alert Level (VAL) or distribute a Volcano Alert Bulletin (VAB), it’s all about the actual eruption, with not as much about what this means for people and what information they need to respond.

So while we know a lot of about the volcanoes, we are still learning about the impacts of ashfalls. Impacts from ashfall can affect lots of different people, from decision makers to emergency managers to the media to airlines and people and infrastructure in the path of ashfall. To assist us and the groups of people who have a variety of questions about these impacts, there is a newly redesigned web platform to help explain what happens when a volcano erupts and what people can do about it.

I sat down with Dr. Graham Leonard, one of the main coordinators for the development of this website, to talk about this new “Wikipedia” for volcanic impacts. Dr. Leonard has been involved in this new resource.

Q. Why do we need a whole “encyclopaedia” for ashfall impacts?

A. Because different groups of people need to know different information about the impacts of a volcano erupting. For example, health professionals need to know about how ash fall affects human health. People from power companies need to know about how ashfall will affect power lines. Farmers need to know about what ashfall can do to their crops, the land and the animals they work with and so on… Ashfall can affect every aspect of our society and the environment, so one size does not fit everyone when it comes to ashfall information.

Q. What’s on the new website?

A. The site has undergone a complete review with a large amount of new content. Content on the web page covers volcanic ash and gas, buildings, transportation, power supply, health, agriculture (plants and animals), water and waste water, equipment and communications, case studies, clean up and disposal. There is a ‘what can I do section’ and educational posters and booklets, and a range of advice throughout the site.

Q. How long has it taken to develop this website?

A. About a decade. We’ve taken case studies from around the globe, painstakingly asking questions of communities and groups affected by ashfall. We have case studies from Philippines, New Zealand, Chile, Alaska, Papua New Guinea, the Caribbean, Vanuatu, Indonesia and Iceland. Researchers from around the world have contributed to this website.

Q. Why is GeoNet involved?

A. We have a lot of volcanoes in New Zealand and the GNS Science researchers who work with the GeoNet project have contributed a great deal of research, through case studies on Ruapehu, White Island, Raoul Island and Tongariro. The web page is hosted by the USGS Volcano Hazards Programme, with support from IAVCEI's CAV and IVHHN Commissions, GNS Science, Canterbury and Massey Universities to provide the content. Before and during an eruption we need to be able to quickly connect the public to this information on what to do in an ashfall.

We are proud of our contribution to this global initiative.

Q. Where can people who want to do know about volcanic ashfall go to find out the latest information?

A. We’ve been working with the City on Volcanoes Commission which is part of IAVCEI (International Association of Volcanology and Chemistry of the Earths Interior) to develop a “web encyclopaedia” which provides the latest information on the impacts of volcanic ashfall and how to deal with it.

For more information, go to:

The new and revised web page; https://volcanoes.usgs.gov/volcanic_ash/.

This morning our web camera on the south side of Mt Ruapehu captured a sequence of images that suggested Mt Ruapehu may have erupted, between 7.20am and 8.20 am. After the examination of the other monitoring data we are able to confirm it has not erupted. These data include seismic activity and the lake temperature.
However we are able to confirm there is a very strong south westerly wind blowing around and over the volcano this morning. This wind produced the cloud effect that the camera has captured.

When a volcanic eruption occurs or unrest starts to develop, one of the first questions the GeoNet team usually face is; what is the history of activity at this volcano, how big have eruptions been or how often have they occurred?  The answers to these come from detailed geological investigations into the past eruptions. This last week a team has been drilling into the floor of Orakei Basin in Auckland to collect evidence of past eruptions from the Auckland Volcanic Field. Although Orakei Basin is presently a shallow estuary, following the volcanic explosion that formed it, it became a deep freshwater lake collecting sediment, volcanic ash and biotic remains. These lake sediments form an essential resource for putting together the history of past eruptions in the Auckland City area.

One of the challenges in Auckland is finding a complete or overlapping geological record of the eruptions. Orakei Basin formed about 80-100,000 years ago and we know from other work that volcanic ash layers are often well preserved in the sediments on lake floors. The solution to our problem lies in recovering a complete core thru the sediments, with the volcanic ash layers been part of the sequence. To achieve this, the DEVORA research project has mounted a drill rig on a barge and floated it out on to the basin and drilled where they think the sediments are the thickest.

The old adage is very true – the past is the key to the present. The more we understand about Auckland’s volcanic past, the more we can plan for future volcanic eruptions.  The sediments infilling the basin were penetrated to 105 m depth and drilling stopped in the volcanic debris thrown up during the formation of the Orakei Crater. The ash layers found in the sediment cores will be micro-analysed and then compared to layers on land in Auckland, giving a more complete sequence of eruptions for the Volcanic Field. Also contained in the sediments are aspects of past climates.  Understanding why and how quickly climate changed will be invaluable for informing the nature and impacts of future climate changes on northern New Zealand.

The shorts and t-shirt weather many have been experiencing may have been great for tan lines but the humid and cloudy conditions in the Bay of Plenty have not helped us with our monitoring flights for White Island (Whaakari). However yesterday the weather finally did allow for a monitoring flight to White Island.  The gas output from the volcano hasn’t changed much. This great weather also gave us unparalleled views of the Crater Lake, which also remains unchanged.

 

About our monitoring flights

We use several techniques to monitor and evaluate the volcanic gas output from White Island.

About once a month we plan to make airborne measurements of sulphur dioxide (SO2), carbon dioxide (CO2) and hydrogen sulphide (H2S) outputs from the volcano. The recent humid conditions in the Bay of Plenty have challenged us, however yesterday we made a successful flight.

To put some context around what White Island is currently doing, late last year the gas output averaged about 370 tons per day for SO2, 2100 tons per day for CO2 and 20 tons per day for H2S. During our flight yesterday (February 4) we measured 450 tons per day of SO2, 2100 tons per day of CO2 and 20 tons per day of H2S. These results are all very similar to our other recent measurements.

Two DOAS SO2 gas spectrometers are also installed on the island and under favourable conditions measure the sulphur dioxide (SO2) gas output. This has averaged around 300 tons per day in 2015, ranging from 120 to 750 tons per day.  During January- February 2016 it has ranged 180-670 tons per day.

We are crossing our fingers that the good weather holds for the next gas monitoring “fly by”.

Last week, we got a reminder about volcano hazards from the Tongariro eruptions in 2012. One of the stream valleys draining from near the Te Maari crater at Tongariro flooded, creating lahar-like conditions in the valley. Debris (sand, clay and rock) left over from the 2012 eruptions was remobilised by heavy local rainfall and washed out of the valley. Minor damage was done to a walking track.

Even though it’s been three years since the mountain erupted, moderate amounts of ash, sand and gravel remain as loose debris in the valley; it has never quite been cleared out. Due to the high intensity rain last week, the valley flushed out some more of this debris. We call this process remobilisation and refer to the floods as secondary lahars.

So when this stuff gets moving the consistency can range from that of muddy dishwater to that of thick wet concrete. Depending on the ratio of water to debris, within the flow there will be grain sizes from clay to boulders. This fluid has the potential to pick up much larger boulders and carry them down stream.  This type of flow can be quite damaging when carrying large boulders, so you want to make sure you and all your stuff are out of the way.

These secondary lahars are often referred to by volcanologists as the ‘sting in the tail of a volcanic eruption’. They can deposit volcanic ash and debris over large areas down slope and in river channels. Volcanologist Brad Scott points out we’ve seen several examples of these events in Tongariro National Park. Following the 1995/96 Ruapehu eruptions ash and debris was washed off the mountains for years and similar is now occurring at Tongariro following the 2012 eruption at Te Maari.

Depending on the consistency of the flow the scientists have several technical names for these (volcanic mud flow, debris flow or lahar). In all cases it is a mixture of water and volcanic debris that moves rapidly down off the volcano. For now, it looks like Tongariro is still capable of producing these secondary lahars when enough rainfall occurs.  Unfortunately the effects of the 2012 Te Maari eruption are still with us, albeit in a minor way. 

Since the 2012 eruptions, we’ve been keeping an extra close watch on Te Maari (Tongariro), installing extra seismic and GPS sites.  Although the activity has returned to background levels, the eruption has provided us with new research opportunities, particularly for our gas and geophysical scientists who want to further our understanding of what happens after an eruption. 

Over the past two years volcano geophysicist Craig Miller has been undertaking precise gravity measurements at Te Maari to detect changes to the volcano and hydrothermal system since the eruption.  The most recent of these surveys was completed last week. The gravity measurements show a positive increase in the local gravity field around the crater since the eruption.  This increase implies there has been a growth in mass or density of the rocks below the crater.

Coincident with the gravity changes new findings from satellite measurements show a small amount of subsidence or sinking of around 20 mm, per year (the length of a Pineapple Lump sweet) has been occurring in the Te Maari area since 2012.

Given this information, we think these changes are related to changes in temperatures and pressures in the hydrothermal or magmatic systems, specifically as the volcano is getting cooler and depressurising post eruption.   Both gravity and deformation data suggest changes are occurring at a depth of several hundred metres below the crater. Further analysis of the gravity data will identify the likely cause of these changes.

GeoNet continues to keep watching Te Maari closely. These repeat gravity and deformation check-ups help us understand more about the dynamic processes going on under the bonnet of Mt. Tongariro and supplement our standard volcano monitoring.


 


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