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Following the 1995-1996 eruptions of Mt Ruapehu, which were the largest eruptions in New Zealand for 50 years it was realised there was a need for more detailed education about ‘The Volcano Problem’. In December 1997 GNS held its first volcano short course; Volcanoes and Society in Taupo. Now 19 years later the course is still popular and fulfilling a need with emergency managers and operational staff, engineering lifelines, the Ministry of Civil Defence and Emergency Management, students, communications specialists and staff from a SW Pacific volcano observatory.
In 1997 the course covered off: The Volcano Problem, Volcanic Impacts and Mitigation, Volcano Surveillance, Warnings and Alerts and Planning to Respond. In 2016 the course covered: The Volcano Problem, Near Vent Hazards, Volcanic Ash Impacts, Ash and Gas Impacts on Health, NZ Volcanoes, The IWI perspective, GeoNet Volcano monitoring, Warning Communications, Challenges of Modern Media, Communicating Hazard and Risk, Management of Risk and case studies. The content has grown as have the issues we face from volcanoes. This year 15 people attended the course and the Field Trip.
Presenters came from a variety of organisations, including the University of Hawaii, GNS Science, Joint Centre for Disaster Research, BOP Emergency Management, the Ministry of Civil Defence and Emergency Management and Auckland University. Two of the presenters also presented on the 1st course back in 1997. The field trip covered an introduction to ‘Caldera Volcanoes’, aspects of geothermal hazards, volcanic land forms, the 1886 Tarawera eruption and faulting associated with the large caldera volcanoes. The course was well received by the participants. The 2017 course will mark the 20th running of the Volcano Short Course.
Recently we had a short lived episode of volcanic ash emission at White Island and our geologists collected some samples. The ash was what geologists call ‘very fine’, that is the particles are very small. They reported back to us that the ash ‘didn’t show any signs of new magma been involved. So how do they know this?
The traditional method is to place the ash sample under a microscope and describe what you see. This time around they did that, as well as putting some in the new Scanning Electron Microscope (SEM) that our geothermal team has obtained. It has very powerful electron optics. One of the features of an SEM is that you can get up to 60,000X magnification. With this extra magnification we can see all sorts of detail in the ash fragments.
Below are two images of volcanic ash. In the right image is some ash from Yasur volcano in Vanuatu. Here explosions happen very 5-10 minutes from craters full of molten lava and the explosions produce a volcanic ash that is made up almost entirely of fresh magmatic particles. You can see the indentations from the gas bubbles and the ‘long’ needle like structures of the volcanic glass.
In the other image is some of the ash we collected from White Island last week. You can see it is made up of lots of angular fragments and crystals. Most of this sample is broken up rock and crystal. This sample is a marked contrast to the one from Yasur. As we can not see any fresh magmatic glass or material with gas bubbles, we are confident there is no new magma at White Island. The new SEM is going to be a big help when it comes to looking at fine ash samples from our eruptions.
Volcanic ash hazards can be very far reaching and are disruptive and damaging. Volcanic ash affects more people, infrastructure and life than any other eruptive phenomena. It consists of very small jagged pieces of rock and volcanic glass. Ash is abrasive, mildly corrosive and conducts electricity when wet. It does not dissolve in water.
VOLCANIC ALERT BULLETIN: WI – 2016/13
15:20 Monday 3 October 2016
Volcanic Alert Level 1 (no change)
Aviation Colour Code: Yellow (no change)
Recently we have also experienced some issues with the power supplies for some of our remote monitoring gear, mostly related to the accumulative effect of the weather (little sun) and ash on the solar panels. One of the cameras had an issue with the data card. On Friday a team visited the island armed with a new camera, batteries, glass cleaning gear, thermal IR, and gas measuring equipment.
The easterly conditions prevailing when the team got there restricted their access to the summit area. This meant the West Rim camera couldn’t be replaced and they were also unable to make detailed gas measurements as planned. They could visit the other two cameras, clean them, and swap out the batteries. They also visited the larger fumarole, known as F0 and measured its temperature. This had increased about 9 °C and is now 190 °C.
Ash emission has ceased, however White Island is always capable of a new eruption at any time, without any useful warning. We continue to monitor the volcano for possible renewed activity. The Volcanic Alert Level remains at Level 1. The Aviation Colour code remains Yellow.
This morning, steam plumes have been visible above Mt Ruapehu’s Crater Lake. The lake temperature is now 37 ºC as part of a heating episode that began around 2-3 September 2016. No seismic or acoustic activity has been recorded this morning, indicating the steam plume was not generated by activity in the lake. The Volcanic Alert Level for Mt Ruapehu remains at Level 1 (minor volcanic unrest) and the Aviation Colour Code also remains unchanged at Green.
The active crater at Mt Ruapehu is occupied by Crater Lake. Crater Lake displays temperatures that typically range between about 15 and 40 °C and the phases can last between about 9 and 20 months. The lake cooled to a minimum of 12 °C in mid-August and then remained at 13-14 °C until early September when it started to heat again. Based on past experience, as the lake continues to heat up, more occasional steam plumes can be expected. This is often controlled by atmospheric conditions near the mountain.
There have been no local volcanic earthquakes or changes in the levels of volcanic tremor this morning on the GeoNet instruments at Ruapehu. GNS Science volcanologists continue to closely monitor Ruapehu through the GeoNet project.
phone 07 3748211
Observations over the weekend suggest no further sustained ash emissions have occurred from the active vents. Occasionally images on the web camera indicate very minor amounts of ash may be present in the steam plumes, but this has not been confirmed. Such intermittent appearance of ash is likely due to shedding of debris on the fumarole walls and may be expected to continue. The seismic and acoustic activity remains low, and the gas flux from the island has not changed substantially during this minor activity.
Although Tuesday’s eruption has ceased, White Island is always capable of a new eruption at any time, without prior warning. GeoNet continues to monitor the volcano for possible renewed activity.
phone 07 3748211
Analysis of ash collected on Wednesday shows no evidence that Tuesday’s eruption was driven by new magma. Instead, gas flow dragged recently loosened material to the surface. Seismic and acoustic activity at remains low, and the gas flux from the island has not changed substantially since before Tuesday’s eruption.
Although Tuesday’s eruption has ceased, White Island is always capable of a new eruption at any time, without prior warning.
GNS Science continues to closely monitor White Island and our other 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.
phone 07 3748211
VOLCANIC ALERT BULLETIN: WI – 2016/10
11:15 Wednesday 14 September 2016
Volcanic Alert Level 3 (no change)
Aviation Colour Code: Orange (no change)
The level of volcanic activity seen yesterday and overnight is very minor, with small amounts of volcanic ash being passively emitted from vent(s) within the active crater. We have reviewed all available data sets; seismic activity remains low, the gas flux remains low and there are no measureable acoustic signals. Some of our cameras are still affected by ash and steam, hence limiting our observations.
The poor light conditions and local high cloud make it difficult to assess the amount of ash present. It does appear the bulk of the emission was yesterday and only minor amounts are now present. Should ash emission increase today there is a low possibility of traces of ash reaching the East Cape area (based on weather and ashfall models).
The current activity is minor. We will review the situation if changes occur. Implications for visitor safety remain unclear. The Volcanic Alert Level remains at Level 3.
VOLCANIC ALERT BULLETIN: WI – 2016/09
15:15 Tuesday 13 September 2016
Volcanic Alert Level 3 (no change)
Aviation Colour Code: Orange (no change)
As far we can tell from our monitoring data there has been no escalation in the level of activity at White Island since late morning. Seismic activity remains low on the island. Some of our cameras are now been affected by ash and steam, so we may not see much from them in the short term.
The level of volcanic activity seen earlier today was very minor, with volcanic ash been passively emitted from a vent on the 2012 lava dome.
The ash is visible on a NZ Metservice visible satellite image, which shows a plume extending offshore of East Cape. Any ash fall will follow wind direction and is likely to be blown offshore over the next day.
The current activity is minor. We will review the situation in the morning unless changes occur overnight. Implications for visitor safety remain unclear.
VOLCANIC ALERT BULLETIN: WI – 2016/08
12:50 pm Tuesday 13 September 2016
Volcanic Alert Level 3 (change from Level 1)
Aviation Colour Code: Orange (change from Green)
The level of volcanic activity at White Island has increased late this morning with minor volcanic ash been passively emitted from a vent on the 2012 lava dome. A report from the island at 11.50 h has confirmed the ash emission.
The Volcanic Alert Level is now raised to Level 3, from Level 1.
The Aviation Colour Code is changed from Green to Orange.
The current activity is minor. We are unsure of the implications for visitor safety and will be issuing a further VAB later this afternoon (3 pm).
GNS staff visited White Island (Whakaari) last week to continue their routine monitoring of the volcano and complete reinstating the levelling and magnetic networks. We also collected thermal IR images of the lava dome area, measured the Crater Lake level and temperature and fumarole temperatures. The Volcanic Alert Level remains at Level 1 (typical background levels).
Observations during this visit confirm the Crater Lake is reforming and growing. The April 27 eruption removed about 13-15 m of lake floor sediments and the new lake is forming at a lower level on the floor of the crater. The lake is currently about 28.4 m below the overflow level. Since 19 May the water level has risen about 3 m and the lake temperature has decreased as it gets larger. The temperature is now 52 ºC. The lake is now a light lime green colour, having changed from a milky grey shortly after the April eruption.
We are sometimes able to get Thermal IR images of a rocky lava mound in the back of the 1978/90 Crater and have established information on the very high temperatures that are present there. This is the same area where a lava dome grew in 2012. There are two areas of hot gas output and the temperature measurements ranged from 198 to 295 ºC. These are down on the measurements we made in August when they ranged 292 to 337 ºC in the hottest area. The temperature of Fumarole 0 (the largest accessible one) has changed little. We measured 170-173 ºC this time and 168-171 ºC last visit.
As we reported in May and June many of our survey pegs were sheared off or broken by the April eruption. This has had implications for the regular surveys we do like the levelling, magnetics and soil gas flux. We have completed reinstalling pegs and made the first magnetic and levelling surveys last week. Minor volcanic unrest continues.
The active vent-crater at Mt Ruapehu is occupied by a crater lake. Recently the lake has been cooling and we even discussed the possibility of new record low temperatures. The Crater Lake displays temperatures that typically range between about 15 and 40 °C. The lake has cooled to a minimum of 12 °C (15 August) but has now started to heat rapidly. GeoNet obtains temperatures from the lake using a data logger with a temperature sensor in the lake and communications via a satellite link.
In early August we discussed the possibility of the post 1995/1996 Crater Lake reaching a new low temperature as the lake was cooling strongly at that time. The lake reached a new minimum temperature of 12.0 °C on 15 August. For much of August the lake temperature ranged 13-14 °C, occasionally looking like it maybe going to turn and start heating. The temperature was starting to rise, very slowly, in late-August, but with quite a bit a lot of variability. However by 2 September a rising trend was clearly established. The lake temperature is now 17.6 °C.
On May 11 2016 the lake reached a high of 46°C, the highest we have observed since it reformed in 1999-2000. This high temperature was also accompanied by volcanic tremor and an increase in the output of volcanic gas. The Volcanic Alert Level (VAL) was raised to Level 2 at that time, lowering to Level 1 in early July when the gas output and volcanic tremor levels declined. About 2 days after the lake temperature stared to rise on 2 September, the level of volcanic tremor also started to rise and has remained present since 4 September. The heating and cooling cycles are controlled by a mix of volcano and geothermal processes. Further sampling and visits to the Crater Lake are planned as the weather allows, being part of the standard GeoNet monitoring programme for Mt Ruapehu.
The workshop was structured around several modules that walked along the pathway outlined for the day. We started looking at various recent examples of eruptions that have produced significant ballistic falls in Japan and New Zealand. The group then compared and contrasted the hazard and risk environments at New Zealand volcanoes that have or could produce ballistics. We looked at Te Maari, White Island, Ruapehu and Auckland. The next item was based on ballistic hazard maps and display of intensity information. The module explored the way and types of information we could put on maps. Do we show risk or hazard or intensity metrics? Do we look at long-term and background situations versus crisis ones. How can we consolidate all these needs and products?
This lead to a session looking at how we collect data about the deposits, what are the key variables we should look for to collect quality data. What were some of the lessons from recent eruptions? What are the data gaps and limitations and how do we address this. Based on this the workshop looked at how we can create numerical models from these data and the parameters we need to know. The participants then got to use a model (Ballista) to see what the effect was on changing input parameters (direction, elevation, velocity etc.). Will a fridge sized block go as far as a baseball sized one? Now that we knew were the blocks would go it was time to look at the exposure and vulnerability of things in the way. This included infrastructure and people. The results from Canterbury Universities cannon experiments were one of the highlights of the day. How much damage does a block tossed from a volcano do a couple of kilometres away!
This week we have established a new target on the crater rim, so we can start following the water level changes in the new lake, which is now forming on the crater floor. The Crater Lake(s) at White Island have had quite a history of change since the first major lake started to form in 2003. From mid-2003 to early 2006 the water level rose about 26 metres, getting to within 2 meters of overflow. The lake then fell to be about 23 meters lower by mid-2007. During this time the lake was heating, so it was basically being evaporated away. It refilled to about 7 metres below overflow by early 2009 and stayed there until heating started in late 2010. The lake again evaporated away. Small eruptions followed in August and October 2013.
The lake started to reform in November 2013. From December 2013 to May 2014 the lake rose about 3 metres and then remained unchanged until June 2015. Then the water level rose another 2 metres before again starting to evaporate away in March 2016, falling over 2 metres before the 27 April eruption. Conditions are now stable enough for us to start monitoring the water level again via the web camera images. The Crater Lake temperature is now 60 °C and the water level about 31 m below overflow.
The volcanic alert level for Mt Ruapehu remains at Volcanic Alert Level 1 (minor volcanic unrest). The Aviation Colour Code also remains unchanged at Green.
The gas flight completed on August 10 recorded the volcanic gas at levels typical of low-background output for Mt Ruapehu. Convection was noted in the lake. On August 11 a Crater Lake sampling for gas and water was also completed. Up welling was again obvious in the lake and was outlined by sulphur slicks, which are frequently seen when the lake is convecting. The lake was a dark green-grey colour and was overflowing. There was a fairly strong sulphur smell near the lake. The lake temperature was measured at 12.6 ºC, consistent with the data logger observations. Today the data logger reports a temperature of 12.9 ºC.
The level of volcanic tremor which was elevated to moderate levels in May-June has declined and is now at typical background levels. Data available at present indicates the level of volcanic unrest at Mt Ruapehu is low.
GNS Science continues to closely monitor Mt Ruapehu and our other 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.
Phone 07 3748211
The active vent-crater at Mt Ruapehu is occupied by a crater lake. This summit Crater Lake displays temperatures that typically range between about 15 and 40 °C. This has been a common feature of the Crater Lake since the mid 1960’s. The lake took several years to refill and become established following the 1995 and 1996 eruptions. GeoNet obtains temperatures from the lake using a data logger with a temperature sensor in the lake and communications via a satellite link.
Since May the temperature of the Crater Lake has been declining and continues to do so. The lake is now 13.5 °C and has been cooling at about 0.5 °C per day. In August 2014 the temperature was just under 15 °C, the lowest since the 1995/1996 eruptions. Now the lake is cooler by about 1°C. We have measured cooler temperatures more than 10 times in the 1980’s and 90’s. Cool lake temperatures are not that unusual. The heating and cooling cycles are controlled by a mix of volcano and geothermal processes. The heat flow into the volcano from the hot and sometimes molten rock under it just gets turned on and off, like a tap. Then the lake heats or cools and maybe sets a new record.
On 11 May 2016 the lake reached a high of 46°C, the highest we have observed since it reformed in 1999-2000. This high temperature was also accompanied by volcanic tremor and an increase in the output of volcanic gas. The Volcanic Alert Level (VAL) was raised to Level 2 at that time, lowering to Level 1 in early July when the gas output and volcanic tremor levels declined.
During the last 50 or so years Mt Ruapehu has erupted often and one trend we have noticed is that the eruptions occur from a hot lake. However we have also noted a few from a cold lake. They do not occur every time the lake gets hot or cold, however if one does occur it will more likely be at one of these extremes. This becomes a time when we pay some extra attention to the status of the volcano. Further sampling and visits to the Crater Lake are planned as the weather allows, being part of the standard GeoNet monitoring programme for Mt Ruapehu.