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In the 15 years since GeoNet was created many people have worked as a part of the Volcano team. Several have been with us from the start, others have joined along the way, while other have come and gone. There are a few who date back to volcanology in GNS Science and three that date back to the DSIR (Dept. of Scientific and Industrial Research) which was the forerunner to GNS Science. As you will see many have worked all over the world on many varied volcanoes and have a lot of experience in how to deal with ‘volcano crises. Skills range from building monitoring networks, to geology, geophysics, geodesy, geochemistry, social science and communications.
In July 2001 I was still in primary school and I had no idea what GNS Science was, or what GeoNet would become, I just wanted to be a fireman. Today I'm a Volcanic Operations Technician (equally as awesome), part of a team of technicians that make sure GeoNet's monitoring equipment around New Zealand keeps providing useful information on the state of volcanos, earthquakes, and ground deformation.
In July 2001 I was working for GNS Science in the Geothermal lab and already involved in volcanoes and geothermal systems. Today I’m the volcano geochemistry technician for the GeoNet volcano team.
In July 2001 I was working for GNS Science undertaking Geothermal and volcano fluid research. This took me to volcanoes and geothermal systems and I was keen on the role gases play. Today I’m the Snr Volcanic Fluids geochemist for GeoNet.
In July 2001 when GeoNet started I had just finished my first year at university at Caltech in Los Angeles; three months before I had decided to switch my degree from astronomy to geology. A year and a half later I decided to be a volcanologist and went on to complete my masters (University of Bristol) and PhD (University of Oregon). I joined GNS Science in 2012 as a post-doc and became permanent staff in 2014. Today I'm a volcanic hazard and risk modeller, I serve as a GeoNet volcano duty officer, and am committed to doing what I can to minimise the impact of future New Zealand eruptions through monitoring and research.
In July 2001 when GeoNet started I was nearing my first year of PhD in the UK, studying how volcanoes persistently release gas for years without erupting. After working in the Eastern Caribbean for 5 years as a volcanologist, I joined GNS Science in May 2009 as a volcano geodesist. Today, I head the Volcanology Department and volcano monitoring team.
In July 2001 when GeoNet started, I had just finished my exams (GCSE's) at high school in the South West of the UK. After more exams, a couple of degrees and a detour in Italy I arrived at GNS Science in 2013. Today I am an InSAR scientist looking at crustal deformation across New Zealand from space (satellites).
In 2001 I was at the Aso Volcanological Laboratory in Japan (visiting Professor) for a year, comparing our monitoring techniques with theirs. Before going to Japan I was experimenting with the first cell-phone connected strong motion Etnas, and was working on the first volcano-cams. Today I’m the Snr volcano geophysicist in GeoNet and work across many volcano problems.
In 2001 I was still at University in UK and knew nothing of GeoNet. I joined GNS Science in 2007 as an operations technician and work in the GeoNet project looking after the seismic and GPS equipment.
In July 2001 when GeoNet started I was with the University of Leeds (UK) and working at Montserrat Volcano Observatory (West Indies) conducting research on seismicity of Soufriere Hills volcano. Today I’m a Snr Volcano geophysicist with GNS Science, joined in 2006 and conduct research on volcano seismic and acoustic properties.
In July 2001 when GeoNet started I was in Montserrat, West Indies working at the Volcano Observatory as the Director. I joined GNS Science in 2006 as a physical volcanologist. Today I'm Director of the Natural Hazards Division (and still very interested in what the volcanoes are doing!).
In 2001, I was studying for my MSc degree in Earth Sciences at University of Waikato. I joined GNS Science in 2002 as a Volcanology Technician and today, I am a Volcano Geologist. I study the processes responsible for generating eruptions and the surface effects once the eruption has begun. I am part of the Duty Officer team.
In July 2001 when GeoNet started I was at Free University of Brussels, Belgium doing my PhD on the geochemistry of fluids and CO2 degassing on Indonesia volcanoes (Papandayan and Kelud volcanoes). I joined GNS Science in 2009 as a volcanic gas geochemist. My role at GeoNet is to monitor gas emission from New Zealand volcanoes (White Island, Ruapehu, Ngauruhoe, Tongariro etc.), contribute to the interpretation of the geochemical data and contribute as a duty officer.
In July 2001 I was working in mining and mineral exploration geophysics in Australia. I joined GeoNet in November 2002 as a volcano geophysicist and later became the Volcano Network Coordinator. In this role I oversaw the modernisation and expansion of New Zealand's volcano monitoring infrastructure. Since 2003 I have been a member of the duty team and have been involved in the response to many volcanic events. I am currently studying for a PhD in geophysics (investigating changes in gravity fields that occur prior to and after eruptions) and will return to GeoNet/GNS in 2018.
In July 2001 when GeoNet started, I was working for GNS Science as a volcanology technician, working on aspect of physical volcanology (rocks and pumice). I’m currently on leave completing my PhD on volcano the geothermal field stratigraphy.
In July 2001 when GeoNet started, I was in 6th form (Year 12) at Tauhara College in Taupo. I started at GNS Science in 2002 as a summer student, and went on to do my PhD at Massey University, which included reviewing New Zealand's Volcanic Alert Level system in 2014. Today I am a Hazard and Risk Management Researcher in the Social Science Department at GNS Science.
In July 2001 when GeoNet started I was working for GNS Science in the volcanology section as the Volcano Monitoring Coordinator (monitoring was part of research then). I have been involved in volcanology for over 40 years (started with DSIR). I have been involved in numerous volcano crises in New Zealand and the SW Pacific. Today I'm the volcano communication specialist for GeoNet, contribute as a duty officer, the routine volcano monitoring and outreach functions of GeoNet and GNS.
In July 2001 when GeoNet started I was working for GNS Science as a volcano geophysicist. I was working on models of the seismic activity that may occur before a large volcanic eruption and monitoring earthquakes at geothermal systems and the active volcanoes. Today I’m a Snr Volcano geophysicist still with interested in earthquakes at geothermal systems and the active volcanoes and how GeoNet deals with data.
Working our way south we start at Monowai in the northern Kermadecs. Monowai is a submarine volcano about 380 km northeast of Raoul Island (or 1400 km northeast of Auckland) and the summit lies about 100 m below the sea surface. Volcanic earthquake activity from Monowai appears on the seismograph at Rarotonga hence we are able to follow the activity. Routine aerial patrols by the RNZAF confirm the activity. The RNZAF pass on pictures of plumes generated by the activity. Activity is regular and noted 3-10 days a month, making it one of our most active volcanoes at the moment.
Following a sequence of earthquakes that lasted several days (but stopped 3 days before) Raoul Island erupted without warning at around 8:20 in the morning of 17 March 2006. The eruption continued for around 30 minutes and created several new vents within and near Green Lake. Scientists found no evidence for new magma associated with this eruption and believe the eruption was caused by a pulse of volcanic gas and volatiles been released from depth which accumulated beneath a sealed hydrothermal system until the pressure was great enough to blow the seal and cause the eruption. Tragically, a Department of Conservation employee was killed by this eruption. Following this eruption GeoNet worked with DOC to further enhance the monitoring programme on the island.
Large pumice rafts were identified near the Kermadec Islands in early August. Analysis of remote sensing data (satellite images) has shown that these came from a submarine eruption at Havre submarine volcano around 17-18 July 2012. Havre lies about 230 km SW of Raoul Island or 860 km NE of Auckland. The pumice extended in a north-east direction for about 280 km in late July and was reported over 600 km long later in August. Havre Seamount was confirmed as the source following a science cruise by NIWA.
50 km off the Bay of Plenty coast lies White Island (Whakaari) an iconic view as one drives along the coast. In 2011 volcanic unrest started at Whakaari, the Crater Lake started to heat and shrink. Following a rapid water level rise (27-28 July) the volcano started erupting explosively on 5 August 2012, being followed by a period of ash emission. In late November 2012 a small lava extrusion was visible. Geysering activity was common in the reforming lake during early-mid 2013. This was followed on 20 August 2013 by an explosive eruption, with more explosive eruptions on 4, 8 and 11 October. The Crater Lake re-established after this and the water level rose. The level of volcanic unrest was variable in 2014-15. On 27 April 2016 further violent explosive eruptions occurred at White Island.
Around mid-night on 6 August 2012 the upper Te Maari crater on the north side of Mt Tongariro burst back into life after 119 years of quiescence. Te Maari had experienced local earthquake activity for 4 weeks and changes in the volcanic gas output. This short period of unrest enabled some preparatory actions by responding agencies and local residents. The 6 August 2012 eruption ejected blocks over 6 km2 and a debris flow occurred down a valley to the west, with minor ashfall occurring as far away as Hawkes Bay. The debris flow changed drainage and formed ponds, which broke out later forming small lahars. A semi-circular rift had formed south of upper Te Maari Crater, containing many small vents. A further explosive eruption occurred on 21 November. Minor remobilisation floods have continued. The output of volcanic gas declined after the eruptions.
On 4 October 2006 the GeoNet monitoring equipment detected what appeared as a small volcanic eruption at Ruapehu. It wasn’t until the weather improved 2 days later that the eruption was confirmed. A small hydrothermal eruption had occurred with the effects of the eruption been confined to the lake basin and having only minimal impact. There was evidence of wave action up to 4-5m above the lake surface; this was not high enough to flow over the tephra dam that blocked the outlet and generate a lahar at that time.
Mt Ruapehu erupted again on 25 September 2007 and produced two lahars, a moderate eruption column to about 15,000 feet, with ash fall and rock falls across the summit of the volcano. This eruption was similar to the 1969, 1975 and 1988 eruptions. It was smaller than the 1969 and 1975 events, but larger than 1988. All evidence available indicates the eruption was hydrothermal in nature. A ballistic (rock fall) apron extended north from the lake, and actually exceeded the ash fallout zone. Typically ash travels further than the heavier ballistics, however in this case the ballistic rocks were ejected with sufficient force to out-travel the lighter ash material. One lahar travelled approximately 1 km into the Whakapapa ski field, reaching half-way down the Far West T-bar to an altitude of c. 2100 m. The other snow slurry lahar travelled down the Whangaehu River, leaving a deposit c. 80 m wide and 1 - 3 m thick near the Round-The-Mountain track bridge 7 km from Crater Lake.
Not to be left out in 2006 Ngauruhoe reminded us the he is still an active volcano when a period of volcanic unrest started in May. The seismic activity around Ngauruhoe increased above the typical background level in June so the Volcanic Alert Level was raised to Level 1. Over the next two years GeoNet recorded an average of 5 to 30 earthquakes a day close to Ngauruhoe, though the maximum daily number was as high as 80. After mid-2008 the number of earthquakes returned to a typical level of a few per week or less. This increase in earthquake activity did not necessarily mean that an eruption is imminent. The Volcanic Alert Level was lowered to Level 0 in December 2008.
To get around this volcanologists use two display techniques called RSAM and SSAM. RSAM stands for Real-time Seismic-Amplitude Measurement. It represents the overall signal size over periods of 10 minutes. While SSAM stands for Seismic Spectral-Amplitude Measurement. It shows the relative signal size in different frequency bands. Different seismic signals have energy at different frequencies. These tools do help use differentiate the source of some common seismic signals like surf, wind, volcanic tremor and traffic.
A problem with RSAM is that it measures the overall signal size regardless of what produces the signal. If the signal is caused by volcanic tremor then RSAM is very useful. But when the wind blows strongly the RSAM value will still go up and scientists don't learn anything about the volcano, only the weather! The key is to look at RSAM and SSAM plots together. RSAM will give us a measure of the signal size and SSAM more information on the likely source of the signal.
The examples below show the effects of the gales at two of our sites; Ngauruhoe and Karewarewa.
VOLCANIC ALERT BULLETIN: RUA – 2016/07
10:30 am Tuesday 5 July 2016
Alert Status: Mt Ruapehu Volcano
Volcanic Alert Level 1 (change from Level 2)
Aviation Colour Code: Green (change from Yellow)
The moderate to high level of volcanic unrest at Mt Ruapehu is no longer present and the Volcanic Alert Level is now lowered to Volcanic Alert Level 1, minor volcanic unrest. The gas emissions decreased and the level of volcanic tremor has also declined. The temperature of the summit Crater Lake has declined from 46 ºC (11 May) and is now at 23 ºC. The Aviation Colour Code is also changed, going from Yellow to Green.
A gas flight was completed yesterday and recorded the gas output at levels typical of background for Mt Ruapehu. The level of volcanic tremor which has been elevated to moderate levels has declined and shows now similar levels to what it was in the second half of 2015. The lake temperature measured by the outlet data logger is now 23 ºC. After reaching a high of 46 ºC on May 11 the lake started to cool to the current value of 23 ºC.
Data available at present indicates the period of elevated volcanic unrest at Mt Ruapehu is over. The volcanic alert level for Mt Ruapehu is now lowered Volcanic Alert Level 1 (minor volcanic unrest). The Aviation Colour Code is also changed from Yellow to Green.
GNS Science volcanologists continue to closely monitor Ruapehu through the GeoNet project.
Caldera volcanoes are a special type of volcano and here in New Zealand we have several examples of these. Eruptions from these volcanoes are very rare, however they can undergo periods of volcanic unrest: wake up roll over and go back to sleep. The Okataina and Taupo Volcanic Centres are regarded as some of the most active caldera systems in the world, and yet little has been done to prepare for the consequences of an unrest event. Caldera unrest, consists of earthquakes, ground deformation, geothermal changes and gas flux could occur. These phenomena can pose hazards which need to be adequately managed.
It was recognised there was a gap in advice available for local government and other agencies dealing with the effects of caldera volcanoes which lead to the formation of the Caldera Advisory Group (CAG). It has been identified that caldera unrest could last for significant periods of time (years to decades) and the effect of this would have a profound impact on the social and economic environments. The work of the CAG is to identify the major potential impacts of caldera unrest and to address each of the areas identified. Caldera unrest is also of "national interest" given the likely impacts.
To further develop the understanding of caldera unrest the CAG is host the inaugural Caldera Stakeholder Symposium in Taupo on Monday 4 July. The intention of the symposium is to provide key agencies with information on what caldera volcanoes are, their potential risks and the disruption they could pose on society (and businesses) when an unrest episode eventuates. With specialist guest speakers and tailored workshops, the symposium will provide a timely opportunity to network, share knowledge, and to gain new insights. The symposium is aimed at:
- Planners, asset managers, emergency managers, executives and elected members from local government and other related businesses
- Central government agencies (including emergency services)
- Infrastructure providers (lifelines utility companies)
- Other sector businesses/industries including insurance companies, real estate institutions, banking sector, agriculture/horticulture associations.
If you have any questions or require any further information, please contact Sarah-Jane Edgar at Waikato Regional Council or click here to visit the CAG website or learn more about New Zealand’s active volcanoes or view a presentation on Caldera Unrest management.
The May 2016 eruption was from 3 sources, the most active been the two smaller 'vents/collapse pits' to the west of the main Mud Rift. These were formed in 1981. We have not been able to see anything on our nearest seismographs. It appears to be mainly steam and fine sands-muds involved. There is lots of evidence of fluids flooding in to rift, especially at the west end. Vegetation nearby is stressed and browning off, but is not damaged by the eruption (no broken limbs etc). There is also some evidence of collapse around the edges of the two smaller vents. Over all it appears as a very short lived event, steam driven with a lot of water also involved (think muddy geyser).
There are two large crater lakes nearby; Inferno Crater Lake and Frying Pan Lake. These are jointly monitoring by GeoNet and the BOP and Waikato Regional Council’s. Inferno Crater is remarkable in that the water level fluctuates through 6-9 meters and over flows about every 40 days. Meanwhile Frying Pan Lake is always flowing, today around 80 litres per sec. In the 1980’s it was closer to 100 litres per sec. These crater lakes display a unique interaction, as the water level of Inferno falls the flow from Frying Pan increases and vice versa. This is termed ‘exchange of function’ and is often observed in hot springs.
From January through to early April 2016 Inferno Crater Lake experienced a ‘high stand’, many of these have occurred since the 1970’s when detailed monitoring started of the lakes. During these times more steam energy is present in the Inferno portion of the geothermal system. This was particularily noticed in 1978/79 and 1981. It would appear this increase of steam through the system was responsible for driving the reactivation of the Mud Rift in May 2016. We have located 47 earthquakes within about 10 km of Waimangu in the last year. In the last 6 years we have located 388, which is typically 64 per year.
Recent visits to the volcano have confirmed the output of volcanic gas (carbon dioxide CO2, hydrogen sulphide H2S and sulphur dioxide SO2) remains elevated above background levels but is declining. The lake temperature reached a high of 46 ºC on May 11 then the lake started to cool, declining to 30 ºC by June 2. Since then it has risen to the current temperature of 32 ºC. Water samples have been collected from the Crater Lake for chemical analysis. Moderate to low levels of volcanic tremor continue.
Data available at present indicates volcanic unrest continues at Mt Ruapehu. The volcanic alert level for Mt Ruapehu is Volcanic Alert Level 2 (moderate to heightened unrest). The Aviation Colour Code is Yellow. GNS Science volcanologists continue to closely monitor Ruapehu through the GeoNet project.
phone 07 3748211
Thermal IR images have established very high temperatures are present on a mound in the back of the 1978/90 Crater. This is the same area where a dome grew in 2012. There are two areas of hot gas output and the temperatures ranged from 292 to 337 ºC. These are the highest temperatures we have measured since early 2014 when we measured 450 ºC in the same area. The April 27 eruption removed about 13-15 m of lake floor sediments and now a new lake is starting to form at this lower level on the floor of the crater; the temperature is 49 ºC. The temperature of Fumarole 0 (the largest accessible one) has increased from 178 to 188 ºC.
Observations during this visit of the eruption deposits confirm the explosive nature of the April 27 eruption and the complexity. The eruption did produce very energetic blasts and surges. In places it sheared off or broke survey pegs and markers at ground level. Typical of energetic blast and surge events, the deposit is not very thick, ranging from a few mm to 50 mm in thickness. Ballistic blocks were observed in several locations, suggesting more than one source for them. There is also a ‘wet’ surge deposit that is mainly made up of lake floor sediments (muds, sands and sulphur). It is starting to appear the eruption sequence was: the area around the former Donald Duck Crater collapsed and exploded, then the former lake and the sediments in its basin have been erupted forming the blast and surge deposits. This has lowered the lake floor at least 13 m. This was a very energetic phase with both surge and ballistic phases (some post surge). Following this there has been collapse of the 1978/90 Crater walls. Survivability during the eruption would most likely have been low in areas of the Main Crater floor.
The level of volcanic unrest at White Island (Whakaari) declined quickly following the eruption on April 27. The Volcanic Alert level for White Island remains at Level 1. Aviation Colour Code remains Green. GNS Science volcanologists continue to closely monitor White Island through the GeoNet project.
phone 07 3748211
Recent visits to the volcano have measured an increase in the output of volcanic gas. When the weather conditions allow we will be repeating these to see if this continues. The analysis of water samples from the Crater Lake show little change from the previous samples. This implies the Crater Lake geothermal system has not responded to the recent increase in gas and heat through the lake. Moderate levels of volcanic tremor continue and the lake temperature measured by the outlet data logger is now 39 ºC. Some of the decline is caused by rainfall/snow into the lake.
Data available at present indicates volcanic unrest continues at Mt Ruapehu. When weather conditions allow we will be collecting further data. The volcanic alert level for Mt Ruapehu is Volcanic Alert Level 2 (moderate to heightened unrest). The Aviation Colour Code is Yellow.
GNS Science volcanologists continue to closely monitor Ruapehu through the GeoNet project.
phone 07 3748211
About our monitoring
Our volcano monitoring team base their decision on the VAL on how they think the molten material (magma) or its associated gas and fluids are interacting under the volcano. These interactions can produce changes or symptoms that we can measure (e.g. heat flow, seismicity, ground deformation, gas or chemistry changes). The signs of unrest may be more intense than in Volcanic Alert Level 1, or the interpretation of monitoring data by the team more strongly indicates the movement of magma or its associated fluids. There may be a higher likelihood of an eruption than at Volcanic Alert Level 1. A volcano can be at Volcanic Alert Level 2 for months, years or even decades.
Why we changed the VAL for Ruapehu
Given the higher lake temperatures, higher gas output and increased seismic activity, we made a call that the mountain had increased its activity to VAL 2. While at the top end of the level we could have steam and gas driven events (geysering) within the Crater Lake, we are not there at the moment. In the coming days or weeks, we could see activity increase or decrease. If it did increase it would be exciting to see the signs of activity, including steam and gas driven events (geysering) within the Crater Lake! These have often before at Ruapehu (1966-68; June 1978; January-April 1980: February 1982 and May-June 1985). These geysers make for some spectacular viewing but we don’t recommend being too close to the lake should these occur.
Is Ruapehu safe?
It is an active volcano and we should always respect our beautiful mountain. However, although the Volcanic Alert Level has been raised this doesn’t mean you have to avoid the Tongariro National Park. Yes there is a higher likelihood of an eruption developing, however volcanic unrest does not always led to an eruption. Eruptions only affect the summit area of Ruapehu and a few selected valleys. The summit hazard zone defined by DOC should be respected. The public are safe visiting all the normally accessible areas like the visitor centres, cafes, ski fields, lodges, huts, Tongariro Alpine crossing and other lower altitude walks.
NZ Volcanic Alert Level system
In July 2014 the Volcanic Alert Level system used in New Zealand was updated, following a review. One of the big changes was the introduction of two levels to define volcanic unrest (levels 1 and 2). Being able to distinguish between these two levels of unrest was an important part of the need for a change in the Volcanic Alert Level system and is entirely due to advances in volcano monitoring made by the GeoNet project (thanks EQC).
We made two monitoring visits to Mt Ruapehu yesterday, one was a gas flight to measure the gas output and the other was to sample the Crater Lake water and make additional ground based gas measurements. Volcanic gas measurements indicate an increase in the amount of both carbon dioxide (CO2) and sulphur dioxide (SO2) output. The ground based gas measurements were complimentary to the airborne data.
Seismic activity at Mt Ruapehu is usually dominated by volcanic tremor. Since the volcanic earthquakes in late April the seismicity has been dominated by volcanic tremor at varying levels. The level of tremor has increased but is not exceptional in terms of the last few years.
The temperature of the Crater Lake as measured by a data logger near the outlet has been rising and since mid-April 2016 and has risen from 25 °C to 46 °C. For the last couple of days it has ranged between 45 and 46 ºC.
Taken together these data now indicate more volcanic unrest at Mt Ruapehu. The increased gas output coupled with high heat flow and volcanic tremor imply a higher likelihood of activity. At this time these changes at Ruapehu are considered sufficient to change the Volcanic Alert Level. The volcanic alert level for Mt Ruapehu is now raised to Volcanic Alert Level 2 (moderate to heightened unrest). The Aviation Colour Code has also changed, from Green to Yellow.
GNS Science volcanologists continue to closely monitor Ruapehu through the GeoNet project.
Detecting the eruption
To confirm there has been an eruption you need 2-3 definitive pieces of data; typically in volcanology that is seismic and acoustic recordings of the ‘explosion’, maybe ground deformation and visual observations. The April 27 eruption at White Island challenged us on all of these, mainly because it happened at night in an isolated area.
The best data are usually the seismic and acoustic (air pressure waves from explosions), however seeing it happen cannot be beaten. This eruption occurred around 9.30-10 pm and no one was on the island. We recorded a complex pulse of seismic data that lasted about 1½ hours, starting around 9.31 pm. The largest and most energetic portion was at around 9.53 pm, suggesting the eruption climaxed about then. The size of the signal was also ‘small’ compared to past activity (2011-2013), and the acoustic signals were not clear, and were difficult to interpret.
Our gas sensors only work in day light, and need the gas plume to be over them. The web cameras also work best in daylight, although they can gives useful images at night, especially when there is a bright moon. What we didn’t know on the evening was that the blast deposit obscured our web camera on the north rim, so even as the sun came up we still couldn’t see to confirm the activity. Nothing very definitive to work with here, hence we couldn’t confirm the eruption on Wednesday evening.
In hindsight, we now have great images from the NZ MetService rain radar that shows an eruption plume reaching to 3 km by 9.52 pm and over 4 km at 10:00 (It takes 7 minutes for the rain radar to collect a full image). The GPS on the Main Crater floor didn’t record any ground deformation, however there is an apparent ‘shift’ which starts around 9.30 pm and continues to 10.24 pm which we now believe was the antenna losing signal or been coated by ash. Detailed post event processing also shows there are acoustic Signals but they remain inconclusive.
Confirming the eruption
As the day light grew on Thursday morning we were able to see from the Factory camera (Dino) there was an indication of a new deposit. Later in the morning, we also noted that two of our solar panels didn’t start to charge batteries, detected via our battery monitoring systems, suggesting they were covered in ash.
We knew something had happened but it wasn’t until GNS volcanologists flew over the volcano in the afternoon they were able to fully appreciate the impacts of the previous night’s eruption. A dark yellow-green ash deposit from the eruption covered about 80% of the floor of Main Crater, blasted high 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. It extended off the island to the north east.
Impacts and Hazards
The surge deposit obscured our web camera on the north rim, the crater floor GPS , along with all of the solar panel arrays. GNS didn’t consider it safe to visit the Main Crater floor however staff did service the equipment outside of that area to ensure valuable monitoring data continued to reach our volcanologists.
The eruption deposit at the North rim site was typical of what volcanologists refer to as a hot volcanic surge deposit. It was plastered on sides facing the vent, but was absent on shaded/protected surfaces. This indicates the surge travelled horizontally, across the crater floor, so the ash did not fall from the sky as often occurs. It has a texture like ‘apple crumble’ and was very dry, this indicates it was very hot when deposited. Survivability during the eruption would have been low on much of the crater floor.
Questions about White Island (Whakaari) that you were too afraid to ask
So, last Wednesday evening, White Island erupted with no warning. Not a huge event. However the eruption had a really big impact on the island. We are still making sense of all the data we have got so far and are yet to examine the Main Crater floor in detail due to the risk to our staff. We’ve put together some of the questions we’ve been getting asked as well as some questions that haven’t been asked yet, but we think are important. Right, first up:
Q. What’s up with that green ash? Is that mineral makeup?
No, thanks Twitter. It is NOT mineral makeup. That amazing green colour was created from a unique combination of minerals on White Island. The ash contained quite a bit of pale yellow sulphur which appeared as irregular shaped lumps, and some translucent golden yellow grains. This is consistent with the colour of the deposit.
Q. Was there any juvenile material found in the ash?
No. The reason we test for juvenile material is to determine whether there was new magma (lava) coming up OR whether this was older material. New material could indicate that this would have been the start of a whole new phase of activity for White Island; however, in this eruption it only tossed out old lake sediments and crater wall material.
For people who want more science, here it is:
The volcanic blast deposit collected from the North rim site solar panel was found to have no new juvenile material. Most of the ash is strongly hydrothermally altered old rock fragments, with some fresher fragments of volcanic glass and crystal. However these are attached to or form a partial coating of white to pale grey hydrothermal altered material. From our past experience of examining White Island ash we are confident that this is not April 2016 magma (new stuff.
When no juvenile material is found, this means that new magma was not involved in the eruption.
Q. If people were hanging around the crater during the eruption, would they have survived?
We are really happy the eruption happened at night. The blast would have been travelling fast and was hot hence survivability during the eruption would have been low in many areas of the crater.
Q. What can you tell us about this new vent?
During the visit on Thursday afternoon we obtained some thermal images of the crater area, and during the aerial inspection on Friday to measure the gas output we had better views of the 1978/90 Crater area. From the photography and thermal images we were able to identify the location of a new vent that had erupted on Wednesday evening. Significant collapse had also occurred in this area, formally known as Donald Duck Crater (in no way related to Dino). Several meters of Donald Mound have collapsed into the 1978/90 Crater area, taking away our target that was used to calibrated measurements from our web camera images. It had been repainted only 6 days before.
Q. Are we going to call this new vent Venty McVentface?
No. Not even once. Stop asking us that, Reddit. We are much more boring, we go for month/year so we can keep track of them ... once you have 20-30 vents with cool names it becomes a challenge! We have had some great ones; Orca, Gilliver, Rudolf, Donald Mound, Christmas, Noisy Nellie, RF, PJ, TV1, Blue Duck, Donald Duck (when Donald mound and Blue Duck joined), Big John, GIBRUS, just to name few along with the boring ones like 1931, 1971, 1978/90.
Q. Why did the Volcanic Alert Level get lowered so quickly?
Following the eruption the volcano did not start to produce volcanic ash from any of the active vents. The seismic activity remained at relatively low levels and gas emission data indicated SO2 output was at levels similar to those prior to the eruption. As a consequence of the continued lack of activity after the eruption, the Volcanic Alert Level was lowered to Level 2 on Thursday evening. This indicated that the volcano was not erupting but remained in a state of moderate to heightened volcanic unrest.
Q. What’s going to happen next with White Island (Whakaari)?
That’s the $64 million question!. White Island is by far one of our most active volcanoes. Heightened volcanic unrest continues at White Island (Whakaari) and no eruptions have occurred since April 27. Volcanic gas output and seismic activity which is dominated by volcanic tremor increased in 2011 when volcanic unrest developed. That led to the eruptions in 2012 and 2013. These two unrest parameters remain elevated and have defined a ‘new background’. The possibility of further eruptions remains high and the Volcanic Alert Level remains at Level 2 (moderate to heightened volcanic unrest).
White Island can and does continue to intrigue us, providing us rich scientific data that increases our understanding of volcanoes in New Zealand and around the world. We aren’t entirely sure what the volcano will do next.
Volcanic Alert Bulletin WI 2016/06
12:00 pm Monday 9 May 2016
Alert Status: White Island Volcano
Volcanic Alert Level 1 (changed from Level 2)
Aviation Colour Code Yellow (unchanged)
The level of volcanic unrest at White Island (Whakaari) has declined following the eruption on April 27. Both volcanic gas output and seismic activity have decreased. Visual observations from a flight on Friday and seismic observations confirm no further eruptive activity has occurred.
Volcanic Alert Level 1 indicates minor volcanic unrest continues.
The Crater Lake temperature appeared to have reached a maximum on May 3 at 42 °C, however since then the lake has heated to 44 °C. This is the hottest lake temperature we have recorded since the new lake was established post 2000.
The swarm of volcanic earthquakes reported in RUA 2016/02 (3 May) has stopped. However the GeoNet seismic network at Ruapehu continues to record volcanic tremor. The level of volcanic tremor has increased slightly this week, but is at levels lower than those reached in April 2015 when the lake was also heating. Volcanic tremor is always present at Ruapehu, and the level does vary a lot. Research suggests volcanic tremor is linked to both hydrothermal and magmatic processes at Ruapehu and not necessarily an indication of an upcoming eruption.
We will provide more information as it becomes available.
phone 07 3748211
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.
phone 07 3748211