Volcanoes

Under a cloud in the UK

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Having arrived at Heathrow a few hours before the shutdown of all flights over Britain due to the volcanic eruption in Iceland, it has been fascinating to watch the unfolding impact as the flight ban has been extended through the last few days. As with an earthquake or tsunami, a geological process is suddenly thrown into the public consciousness, even though it originates from far away. In this case the process is relatively prolonged and there is no-one who has any idea of how long the eruption might last or how the winds might be moving the ash cloud a week from now. As well as having stressful consequences, there have also been benefits resulting from the ash cloud. I am staying in the south east of England, not far from Gatwick and Heathrow airports. For many people this is the first time ever that they are able to sit in their back yards and have a conversation without being drowned out by the roar of aircraft overhead. The weather has been sunny with clear skies, with no visible sign of the ash cloud that is causing so much disruption. News bulletins are filled with the scientific background, economic predictions, traveler’s personal stories and political commentaries. I have been increasingly grateful for my good fortune in having got here just in time, whilst wondering if my return journey at the end of April will be equally unaffected. There are direct lessons to be learnt for NZ too as Gill Jolly and Graham Leonard, both volcanologists at GNS Science, describe in this media release

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White Island 2

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See the video of our visit to White Island: Here’s a bit more about what we did during our day on there: Karen and Agnes set off with their water monitoring equipment, whilst Brad, Steve and I started the elevation survey, measuring height differences between an extended series of fixed points that had been marked by wooden stakes driven into the ground. Whilst Steve held the survey pole, Brad aimed his leveler at it from an adjacent measurement station and was able to read off the height difference between the two points. By sighting between the points in this way, we continued our survey past some very loud and active fumaroles, in a broad area towards the crater lake. Occasionally we stopped to take photographs of interesting features, or discuss the history of the formations around us. Once or twice we were enveloped in steam and gas from the fumaroles, and rained on by acidic water droplets (acid rain) that gave a burning, prickling sensation to my eyes. Past measurements have shown that the ground near the crater has been rising by two or three centimeters every three months for several years, mainly due to an increase in heat in the ground. From our measurements we found that the hottest area of ground near the most active fumaroles had risen up to a maximum of 50mm since the last survey, with the amount of uplift reducing quickly a short distance away. These results show continuity with the long term trend of uplift. Almost towards the end of the survey, we met up with Karen and Agnes, and I watched them sampling the water from a very active hydrothermal spring that was gushing and splashing nearby. To make a variety of measurements of the water chemistry and isotopes, they scooped water out of the spring and put it into various sampling bottles. Once our survey was done, Brad and I walked over to the lower of two webcams to give the glass a wipe, as the photos had been getting quite fuzzy due to a build up of dust. There in front of the camera was ‘Dino’ in real life. He is a small dinosaur, apparently famous the world over for having arrived mysteriously to take up residence in full view of White Island’s Crater Webcam some years ago: see http://www.geonet.org.nz/volcano/activity/white-island/cameras/whiteisland-latest.html Before we returned to the helicopter, we walked through the ruins of the old sulphur mine, where there were rusted machines and derelict buildings. Finally we were ready to leave and as we turned in a wide loop above White Island, I was very impressed to have been able to have had such a close encounter with such a remarkable place.

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White Island

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Last week I visited the GNS Science office at Wairakei, just outside Taupo. This is where a lot of research is done into New Zealand volcanoes and geothermal fields. First up this morning was a trip to White Island, One of the most frequently active volcanoes in New Zealand, where I assisted a small team of volcanologists on one of their routine visits. The purpose was to test the chemistry of the groundwater appearing out of numerous springs around the crater area, as well as to survey the ground surface elevation to check for sinking or uplift. In the team were GNS scientists Karen Britten, Agnes Mazot, Brad Scott and Steve Sherburn. White Island is 50km north of the Bay of Plenty coast, visible from nearby towns and often seen to be emitting a plume of steam. From the mid seventies to the year 2000 it was frequently in a state of eruption. Since then it has quietened down to become relatively peaceful for the last few years.For our visit we flew by helicopter from Rotorua, first across beautiful farmland and large pine forests, then out to sea where White Island soon loomed up in the distance. I had seen many photos of the island before but was excited to have the opportunity to actually set foot on it in reality. It is a horseshoe shaped island, with a high surrounding ridge around the inner crater area that includes a large yellow greenish crater lake. This lake formed after the most recent eruption phase and is only about 6 years old. On the South East side the ridge is breached in a couple of places, where the land slopes gently to the sea shore at a low angle. On our arrival we flew in from this side, and landed in the hummocky area a couple of hundred metres in from the shore.Our pilot switched off the engine, and immediately the sound of hissing and gushing fumeroles dominated. There was a strong smell of sulphur and clouds of steam wafting up from numerous points further in towards the centre of the main crater. The ground was littered with blocks of scoria and lava bombs from past eruptions. The photo shows a lava bomb that was molten when in landed on top of another rock, before it solidified.

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