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In recent years Unmanned Aerial Vehicles (UAV’s) or, drones, as they are often called, have become a useful tool in going places that are often difficult or dangerous for people to go. We have been using them to make observations of locations that are not safe to visit and making maps of areas. In June we mapped the eruption deposits at Waimangu by UAV and more recently used them extensively to map the fault displacements and landslides produced by the M7.8 Kaikoura Earthquake. In late December we were able to fly the active crater at White Island.
While we have the volcano cams on the island, these are stationary and don’t give us the kind of rich data that a drone can. Since the eruption in late April 2016 the vent area has often been obscured by steam and gas and a small lake also formed for a while. This made it difficult to fully assess the changes to the active crater area. We were able to work out the crater floor was lowered by about 13 m but couldn’t accurately estimate the volume of material erupted as we didn’t have a before and after map. Understanding the volumes involved, distances material was moved etc. helps us better interpret the impacts and mechanism of the April eruption.
We were able to obtain images of the active crater area usually obscured by the gas and steam plume so we could make a new map and Digital Terrain Model (DTM) of the area. We know some of the crater floor was lowered about 13 m by the April eruption, but didn’t have any data on the vent area. During our visit in December we had a light easterly wind blowing the plume away from us and the humidity was low so the amount of steam was also low. Perfect conditions for flying the UAV mission over and in the crater.
Our UAV technician has processed the images and video captured on the day and is now compiling the DTM and surface maps. They are really impressive and are giving us a new insight to the changes within the active crater.
No word yet on what Dino thinks of this new visitor to the island.
White Island (Whakaari)
On November 21 we completed a gas flight at White Island, where we measure sulphur dioxide (SO2), carbon dioxide (CO2) and hydrogen sulphide (H2S). The gas output was down slightly on the October flight. The sulphur dioxide (SO2) has ranged 230-420 tons per day, carbon dioxide (CO2) 1240-1730 tons per day and hydrogen sulphide (H2S) 15-35 tons per day.
The main vent(s) were less audible than in October, still producing a transparent plume at the base/vent which evolved into a vivid white steam plume. There is no lake. Over the last 2-3 months the small lake let on the crater floor was disappeared to leave 5-6 small depressions, some have water ponded in them. The water levels are variable as are the colours of the pools, some are grey and active, others blue/green and passive. We estimated the water levels varied by 2-3 m.
A levelling survey was completed on December 20 to ascertain the amount of ground deformation across the crater floor. Changes show subsidence (20 mm+) focused on the active crater area. Fumarole ‘Zero’ remains very hot, we measured 182 °C. It was 178 °C in October.
We used drones to obtain photography of the active crater area so we can build a new map. We also sampled the gases from the main gas plume using a drone. Maintenance was also completed on the web cameras.
On December 17 we completed a gas flight at Ruapehu, our first successful flight for months. We measure sulphur dioxide (SO2), carbon dioxide (CO2) and hydrogen sulphide (H2S). The gas output was up slightly on the August flight. The sulphur dioxide (SO2) has ranged 19-22 tons per day, carbon dioxide (CO2) 240-640 tons per day and hydrogen sulphide (H2S) 0.6-1.6 tons per day since July.
The Crater Lake was visited to sample the water and collect gases on December 20. The lake temperature was 21.7 °C. Lake was a battleship grey colour with more blue grey water near the lakeshore due to meltwater going into the lake. The central vent was very slightly distinguishable in the right light conditions. The north vent area had a lot of sulphur slicks nearby.
Lake level appeared to be on the high side (summer melt) and the flow at the outlet was estimated at 60-80 L/sec.
Crater Lake temperature has been cooling since early October, when it reached 40 °C. For the last 2-3 weeks it has been around 24-22 °C.
As part of a collaboration with the University of Toronto (Canada) several passive air samplers are being installed on the active volcanoes and in large geothermal areas. These will measure mercury and its isotopes concentrations. The main purposes of the project are to characterize the sources of Mercury and monitor the spatial distribution of Mercury into the atmosphere.
Volcano rundown: let’s start at the top
Starting offshore North of New Zealand, we work our way south along the Kermadecs, beginning with Monowai submarine volcano. There has been no activity noted since 11-12th November. However, we did notice a random pumice raft in the middle of the ocean near Tonga but this looks unrelated to Monowai.
Next is Raoul Island, nothing new is apparent there, only the Crater Lakes showing their usual summer warming cycle, due to the warmer weather.
A team visited White Island (Whakaari) and our ever watching Dino, last Thursday with a film crew and made several observations. The temperature of the main vent in the active crater has declined, down from 280 to around 140 °C. The small pools of water on the crater floor are getting smaller. The temperature of the hottest accessible fumarole (steam vent) remains around 180 °C. The gas flux has varied from around 300 to 600 tons per day of SO2. Overall the situation remains very similar at White Island (Whakaari) to how it was a couple of weeks ago.
Auckland Volcanic Field is also quiet too, no earthquakes near there. Moving south, Okataina Volcanic Centre (this includes Tarawera) is quiet, just a couple of small shallow earthquakes nearby.
The big news in volcano land this week is the that there has been a small steam (hydrothermal eruption) in Lake Rotorua. Eruptions have been known in this area all through our written history (1830 – present), so it’s not too unusual. The occurrence of steam eruptions has been variable in Rotorua, with many during the exploitation of the geothermal system, however they declined after the bore closure (1987). The last significant one was in 2001. We’ll be keeping a close eye on this latest hydrothermal eruption but, as this is pretty much business as usual for this system, we aren’t too concerned about it. We went down to check out the eruption and it didn't leave much interesting evidence
Our central volcanic zone is pretty quiet too. Taupo Volcanic Centre is quiet, just a couple of small earthquakes. Further south, the Tongariro-Ngauruhoe area is very quiet, again just a couple of small earthquakes. A team visited Te Maari and measure 308 °C from the vent here. The volcanic tremor at Ruapehu remains weak. The lake temperature is now 24.5 ˚C, continuing to slowly decline.
Mt. Taranaki continues its silent watch over the West Coast of the North Island.
So that ends our tour. And thankfully, it looks like the volcanoes have continued to ignore the Kaikoura earthquake sequence.
A RNZAF flight on Wednesday November 16 has reported floating pumice to the west of Minerva Reef in an area about 600 km SE of Fiji and 500 km SW of Tonga. We are not aware of any active submarine volcanoes in this area. The nearest active submarine volcano is Monowai (400 km SE) and we know it was active on November 10-11. Monowai usually does not produce pumice rafts, just discoloured plumes.
We have analysed some satellite images from the area using https://worldview.earthdata.nasa.gov/ and can see the pumice rafts in images from November 15 and 16. They extend for more than 100 km in the images. We have not as yet been able to ‘back track’ the pumice in older images to confirm a source location. The pumice is generally seen around 179°W and 179°E and 23° 20” S.
In October 2012 a much larger pumice raft was found (https://goo.gl/8A7c57) and later we found out it came from Harve submarine volcano.
Volcano rundown: let’s start at the top
Starting offshore North of New Zealand, we work our way south along the Kermadecs, beginning with Monowai submarine volcano, which had a brief bit of activity over the 11-12th November that lasted about 24 hours. This is normal behaviour as we see a few days’ of activity every month. Next is Raoul Island, nothing new is apparent there, only the Crater Lakes showing their usual summer warming cycle (climate induced). And it’s a similar situation at White Island. The volcanic tremor levels remain very low and although there have been a couple of earthquakes nearby we see that every other week as well. Auckland is quite too.
Moving on-shore, Okataina Volcanic Centre (this includes Tarawera) is quiet, just a couple of small shallow earthquakes near Kawerau and a half dozen to the south in Waikite Valley (a place no stranger to small earthquake swarms). There were also a couple of earthquakes near the Wairakei geothermal system. Taupo Volcanic Centre is quiet, just 2 events so far this week.However, it is a very different story north of Kuratau (near Turangi) which experienced a sequence of earthquakes between the 10th and 13th of November. We had the story ready to run on Monday, but decided to hold off publishing it because we were focused on the bigger issues of the Kaikoura earthquake.
The sequence has come in four parts to date:
- The first, which included the largest earthquakes, started on November 10 and appeared as a typical main-shock after-shock sequence. The largest of the 27 earthquakes in this part was a magnitude 3.3.
- After a quiescence (aka a geological power nap) of about 21 hours, the second sequence started. It behaved much more like a typical Taupo Volcanic Zone swarm and included 52 earthquakes.
- The third part of the sequence started about 11 hours after the second and was also swarm like (32 earthquakes).
- The fourth part included three magnitude 3 earthquakes and an isolated magnitude 3.2 earthquake on the eastern side of the lake (9 events). This part dropped off before midnight Sunday/Monday and so far has not notably reactivated following the M7.5 sequence - i.e. since the first Kaikoura earthquake.
The earthquakes range in magnitude from a little less than 1.0 to magnitude 3.3. The earthquakes are located between 5 and 11 km deep, with the majority of these between 7-8 km. Small shallow earthquakes like these will be well felt by local residents and we have received many felt reports from the area. It is not clear if the sequence has finished yet. Prolonged earthquake swarms (sequences) are a regular feature of the Taupo Volcanic Zone. One near Matata in the mid-2000’s lasted several years.
Further south, the Tongariro-Ngauruhoe area is very quiet, just a couple of small earthquakes. The volcanic tremor at Ruapehu is slowly declining, heading back towards normal background levels. The lake temperature is now 31 ˚C, slowly declining from the recent maximum of 39 ˚C.
Mt. Taranaki continues its silent watch over the West Coast of the North Island.
So that ends our tour. And thankfully, it looks like the volcanoes have ignored the Kaikoura earthquake(s).
An increase in the strength of volcanic tremor began on October 18, where a sharp increase was noted before the energy declined a day later. Subsequent tremor increases occurred again on October 25 and 28, and currently remains higher than normal. These tremor pulses do not appear to be related to any variation in the lake temperature. Our records show that similar periods of increased volcanic tremor were present May-June 2016, again when the lake temperature was high. Importantly, no eruptive activity or geysering was noted in Crater Lake during the previous periods of volcanic tremor.
Weather conditions have not been ideal for mountain observations. Nevertheless, our scientists will be visiting the lake to collect water samples for further analysis and making a gas flight when the weather conditions improve.
The active crater at Mt Ruapehu is occupied by Crater Lake and it 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 and reached a peak of 39.8°C on October 4.
GNS Science volcanologists continue to closely monitor Ruapehu through the GeoNet project. 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 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.
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).