We’re sitting on an airforce Hercules on the way back to Christchurch. An 8-hour flight is an excellent opportunity to catch up on sleep, data processing, and blog posts.
Erebus itself is quite an unusual volcano – it is home to one of the world’s few persistent lava lakes; large crystals, also called megacrysts, of anorthoclase feldspar are found in its lava; and it is one of a handful of ice-covered volcanoes where flank degassing results in the formation of ice caves (other examples include Mt Rainier and Mt St Helens in the US). As we mentioned in a post a few years back, these ice caves are interesting to scientists for a number of reasons.
While we know of active glaciated volcanoes in the present day, there have been times in the past when most of the earth is thought to have been ice-covered. One theory on how the world ‘defrosted’ is that volcanic carbon dioxide (CO2) emissions caused warming of the atmosphere. One way to better understand what happens to CO2 coming out of glaciated volcanoes is to measure it at a place like Erebus. Since much of the gas that is escaping seems to be associated with heat and steam, we find steaming warm ground, and ice caves that have been shaped by escaping gases – sometimes together with ice towers from steam freezing around gas vents.
A second reason for our interest in Erebus is more local – how does the flank degassing relate to the activity we see at the summit (which includes the lava lake(s) and a number of fumaroles)? Erebus is in an area where the lithosphere is thinning as it is pulled apart along the West Antarctic Rift system – specifically, it is associated with the Terror Rift – so we might expect to see more gas escaping along fractures related to the rifting. But where is the gas really coming from? Is it escaping at shallow depths from the magma that supplies the lava lake? Or is it sourced at much greater depths, escaping from the mantle and finding pathways directly to the surface? Then, as it approaches the surface, with what else can it interact – is there substantial water underground that adds to the gas emitted at the surface?
Our work in these two field seasons is to start answering some of these questions by collecting and analysing gas samples from different sites around the volcano. We sampled gas from fumaroles near the main crater rim, down through warm ground, to ice caves in the lower part of the summit caldera. These sites span about four or five hundred metres vertically, but will hopefully also give us an idea of how emissions vary with distance from the lava lake.
We used a number of sampling methods, partly so we could measure different things, and partly to keep our bases covered in case something went wrong! One set-up for gas sampling is a soil probe connected to a series of copper tubes, which in turn connect to a pump. We usually connected the output to a glass vial that can collect another 12 mL of gas. The pump was left running to flush out ambient air, so that the gas we wanted to measure could fill up the tubes. When we returned, it was time to crimp the ends of the copper tubes. This cold welds them shut and stop the gas escaping.
Another type of measurement was carbon dioxide flux. Unlike the copper tube and glass vial samples, which we must analyse back in the lab, this CO2 analyser immediately tells us the concentration and flux of carbon dioxide. The cylindrical chamber is put on the ground and it measures the changing concentration of CO2, using this to calculate flux (i.e. the amount of CO2 emitted per unit of time). By taking flux measurements at points along a grid, we can extrapolate to get an idea of the rate at which CO2 is emitted from the volcano’s flanks more generally. The main technical challenge here was keeping the instrument warm enough to operate. After one incident of emergency rewarming inside Lyra’s jacket, I ended up making it a sort of tea cosy out of two rock bags separated by a layer of bubble wrap.
The CO2 flux meter and soil probe can both be used to collect gas in a vial or in a special plastic bag. The samples in the bags don’t last long, but can be used with an instrument that we were given a last minute opportunity by the DCO to take along with us – an infrared isotope ratio spectrometer. We set this up in the garage hut and it could, in theory, be used to measure carbon isotope ratios. While a first look suggests some good data, we also had enough technical issues to keep us busy in the garage on bad weather days.
Isotopes are variation on an atom distiguished by the number of neutrons they contain. Having more neutrons does not affect the charge of the atom, but does affect its mass. Carbon has two stable isotopes that occur naturally (as well as carbon 14, which is radioactive). Of the two stable isotopes, carbon 13 has greater mass than carbon 12, because its atoms each contain one more neutron. Carbon from different sources has a different balance of isotopes depending on how and whether it fractionates – that is, how it separates according to mass. Carbon dioxide from deep down in the mantle usually has a relatively heavy isotope ratio, whereas if it undergoes phase changes, such as becoming dissolved and then exolving into a gas again, the heavier isotopes may be separated out. So by looking at the isotope composition of the carbon dioxide, we can start to understand where it has come from and how it has been modified, helping us to address some of those questions I mentioned at the start, about the depths from which the gas is sourced and how it interacts with water.
Also headed back to Christchurch today were a case of copper tubes, glass vials, and sampling bottles. These, we will analyse back in the lab for gas and isotope composition.
We are now back at McMurdo after two and a half weeks in the field. This post was started partway through our season. Unfortunately, I didn’t get a chance to finish and post it in the few hours that the internet connection was up – apologies to our readers for the delay (it’s a harsh continent!)
Our field camp was at Lower Erebus Hut (LEH), on the north side of Erebus. Most of our work, however, was a half hour snowmobile drive around the caldera, at Ice Tower Ridge. This is a line of ice towers and caves that extends southwest from an old Erebus caldera rim up to the summit area. We are looking at gas compositions from this area to see how they vary with distance from the main crater – but this first post will focus more on the practicalities of our work.
Having spent most of my previous two seasons working at LEH and the summit area, Ice Tower Ridge is still fairly new to me. None of the three members of my team are familiar with the area either, so a large part of a day in the field can be spent driving to the site, trying to find cave entrances, and choosing a good place to position instruments.
It usually falls to our mountaineer, Lyra Pierotti, to make sure we can safely access a cave. She often goes ahead to check whether the ice beneath us is sturdy, and to decide how best to enter – whether we can simply crawl in, or whether crampons or ropes might be required. Having someone to get us to our sites makes it a lot easier for us to focus on getting our science equipment set up!
Once inside, we must find suitable places to set up our gas sampling equipment and measure carbon dioxide flux. This can involve some exploration – looking for soft ground or a vent to place soil probes for gas sampling, checking soil temperatures, and ensuring the site is safe to access.
One spot I found was a deep hole with warm air coming out at up to 6 m/s, warmer than the cave air by over ten degrees Celsius.
It is quite warm in the caves – often above freezing, compared to -20°C or lower outside. This can be nice to work in – except that it is also much more humid in the caves, and all the liquid water dripping on us freezes rapidly when we head back out. Not all of our work is done in the ice caves, either. We are also working outside to take gas measurements in areas of warm ground, where heat and gas move more diffusely through the soil.
The Erebus ice caves and geothermal areas are home to unique micro-organisms. This means we do not enter any caves that are pristine (have not been entered previously) or certain areas of warm ground. We also need to take precautions to reduce contamination that in some sites involve sterilising the instruments that come into contact with the ground, and in others require protective clothing.
Some of our work doesn’t require so much preparation, however! One of the sites nearby, Hut Cave, is a good place to work during bad weather since it’s just a few minutes’ walk from camp. I made a couple of trips out to place and retrieve a soil probe, with some copper tubes and a pump attached to collect gas.
Carbon dioxide levels can be high inside some of the caves, so it’s good to have a handheld monitor and someone for backup when investigating the smaller passageways and crevices in search of gas vents.
We made it into about five cave systems this season, and set up multiple sampling sites in some of them. We also spent time above ground collecting gas in areas of warm ground and around the crater rim. Collecting the samples is just the first step, though – I’ll be writing more about what we’re actually looking for in the next post!
As we are just a couple of days out from our planned departure for Erebus, we are finishing off training and testing out some of our equipment to make sure it will work in the field.
On Saturday, we went out for crevasse rescue training, along with another team. They will be working on a glacier, so the training is a useful precaution – in our case, although the upper slopes of Erebus are crevasse-free, our work comes with a small risk of breaking through the top of an ice cave. We may also need to use ropes to access some of the caves.
In the classroom, we went through some knots, principles of crevasse rescue, and self-rescue using prusiks, which are friction hitches tied around a rope. These can attach you securely to the rope when your weight is hanging on them, but slide freely when they are not loaded (usually when your weight is being held by a second prusik). We then headed out to the simulator – an artificial crevasse – a short way by hagglund from McMurdo. Unfortunately, photos are a little scarce as I was busy trying to learn things! We practised self-arrest (to stop ourselves from sliding, or being pulled, into a crevasse) using ice axes, creating anchors to which a rope can be attached and used to rescue a crevasse-fall victim, then put all the elements from our training together to pull either ‘Mr Orange’ or a heavy bag out of the crevasse.
The first part, which was hard enough, was self-arresting with a bag about half my own weight falling down the crevasse attached to the rope behind me. It was then up to my supervisor to secure a second rope into the snow, set up a pulley system, and rescue the bag (which had, by then, hit the bottom). I am not yet confident that I could rescue anyone from a crevasse or ice cave (unless it were myself), so here’s hoping for a safe field season!
It has been snowing a lot this weekend, so I put off going for a walk (until after I finish this post!) and spent another day in the office today.
Our preparation for fieldwork included putting together the system that we would use for gas sampling. This starts with a soil probe, which will go into a vent. Flexible tubing connects it to a series of copper tubes that will be used to collect gas so that we can measure its composition, and analyse helium and other noble gases. A tiny pump draws air through this system so that the air already inside will slowly be flushed out, and the gas from the vent will fill the tubes. On the other side of the pump, some glass vials will collect the outflowing gas for carbon isotope analysis. All of these samples will need to come back to UNM for analyses.
We tried testing the system with the soil probe in a beaker of water. We wanted to find out how long it took for the air in the system to be flushed out, which in this case would be when it filled up with water. It’s much harder for the pump to draw up water than air, though, so while we found a few leaks to deal with, we didn’t manage to time the flushing. Instead, we found the volume of the sampling train by filling it with water. It’s about 120 mL so, at a pumping rate of 10 mL air/min, it would take (in theory) 12 minutes to flush the system. In practise, we think that flushing for a couple of hours should be enough to ensure that we are measuring gas from the vent and not the ambient air.
After dinner, I went back to pack things up…
…and finally, I can head out into the sunshine for a walk, before a busy day tomorrow – getting our cargo ready to fly, more snowmobile training, and packing up our personal gear.
The Volcanofiles have had a long break between fieldwork posts, and there are a few more days to come before I get into the field, so this season’s blog posts will start with today’s non-scientific update on our trip thus far, and some photos from Ross Island, where we are based.
It’s exciting to be back on Ross Island after four years. A few things are different this time around. Instead of working on gas emissions from Erebus lava lake, we are collecting gas samples in the ice caves. Last time, with G-081, (who will also be heading up in January this season) I was in a group of about twelve. Now, I’m part of a much smaller group (event number G-411) – just me, my supervisor, and a mountaineer to help us in the field. This means I’m much more involved in planning our fieldwork, and realising just how much effort goes into supporting Antarctic science.
Since arriving, we’ve had meetings and training to cover several topics, including communications, field safety, working at altitude, and our environmental responsibilities. I’ll go into more detail on the Antarctic Specially Protected Area, or ASPA, and environmental concerns around the ice caves, in a later post.
We completed our food pull today with the help of field centre staff here, so that we have supplies both for the acclimatisation camp at Fang glacier, and for Lower Erebus Hut, or LEH. We also went through the camping and caving equipment that we are borrowing for the trip. For those who didn’t follow our previous trips to Erebus, we spend a couple of nights at an intermediate altitude, in order to help us acclimatise to the lower oxygen availability. Fang is a tent camp, with no buildings, so people from here at McMurdo have to go and set it up every season before science events like ours start coming through. LEH has two huts – one where we cook and work, and a ‘garage hut’ with tools and storage. We can set up our own tents when we arrive.
Now we’re hoping for good weather on Monday, so that Fang camp can be put in. Apparently this was due to happen last week, but weather conditions have intervened. Once Fang is in, we can head up – in the meantime, the carpenters will be opening up Lower Erebus Hut. As you’ve probably gathered, there are a lot of people working hard to make the research down here happen.
Tomorrow, we are planning some crevasse rescue training to prepare for our work in the ice caves. This is weather dependent, of course – as I write this I can see the islands of the Ross Archipelago to the south appearing and disappearing due to what I think is snow! An update on our training will follow, but in the meantime, here are a few photos from our trip so far.
We travelled from Albuquerque, New Mexico, in the USA, where I started a postdoctoral research position in August, to Christchurch, New Zealand, where we were issued clothing and waited for our flight south.
After an early morning start the next day, we got on a C-17 at Christchurch airport, and spent a few hours getting to Ross Island.
One difference from my previous seasons is that we landed out at Pegasus air field, an hour’s drive from McMurdo on ‘Ivan the Terrabus’, as opposed to the sea ice runway that we used in the past, which was much closer to McMurdo.
Unfortunately, I was so disoriented on getting off the plane that I’m not actually sure which direction Erebus is in relative to anything else in these photos!
McMurdo is as built up as ever. We sleep in dorm buildings, work in the Crary lab where we have lab and office space, go to the ‘galley’ for meals, with visits to places like the Science Support Centre for training, or the Berg Field Centre for our field gear. We spend most of our time indoors – but if you remember to look up (provided the visibility is not too bad) it still looks like Antarctica.
When the weather is good, it’s easy enough to take a walk out of town. Last night I visited Scott Base, which was a chance to meet some fellow Kiwis.
The main reason for the walk, though, was to get outside and find some nice views…
…including a first look at Erebus.
If you squint, you may be able to see the summit cone and a tiny plume coming out of it…but in any case, please keep an eye on the blog. We hope to be reporting from up there in a week or so.
This past field season (winter 2013), Erebus volcano was churning out more volcanic bombs than usual. The very lucky field team even got to play with some freshly erupted ones and watch the still molten insides flowing! These bombs can be anywhere from the size you see in the video below to the size of a garage. They are phonolite in composition and come straight from Erebus’s phonolitic lava lake that sits in the summit crater. Generally, the farthest the bombs fly is about 1 km from the crater.
Now that the team is settled in at the Lower Erebus Hut, the live webcams are streaming again. Below are two views, one visible image of the volcano’s summit as viewed from the hut and one infrared image of the lava lake itself from a camera perched up at the rim. These feeds are also available at the Mount Erebus Volcano Observatory website.
Refresh this page for new images.
Erebus volcano as viewed from Lower Erebus Hut:
Erebus lava lake in the infrared:
Stare at these long enough and you might just see an eruption!
The southernmost active volcano in the world tends to get a bit icy over the winter. Volcanology team G-081 arrived at the observatory hut on the side of Erebus volcano one week ago, and they found that what would become their home for the next several weeks had been totally covered in ice over the Antarctic winter!
Just getting up to the hut proved a challenge this season. Nial sent us this update when he had secured internet access:
Well we finally made it up on to Erebus after having our helicopter flight cancelled a couple of times. We flew straight in to the Lower Erebus Hut (which is our main camp on the volcano), pulled all the snowmobiles out of the garage and drove them down to Fang (which is our acclimatisation camp). Starting snowmobiles in a confined space at high altitude is not a very good idea it turns out, and we all ended up with bad headaches. Still, after two days of lying around at Fang camp (the weather was rubbish so we basically just stayed in bed for two days) everyone had acclimatised pretty well and we drove back up to the hut again. The snow conditions are awful for driving this year with huge sastrugi (hard packed snow drifts) everywhere.
The team had a brief weather window after they arrived at the hut, which was just enough to set up tents and clear all the accumulated snow out of the hut, and then the wind picked up to 40 knots and the temperature dropped to -30 and below. The weather has been pretty bad ever since, with low temperatures and very high winds.
What about the camera?
If you’ve been following recent posts, you may be as anxious as we were to hear about the fate of Nial’s thermal camera, which was perched atop the Erebus crater all winter long with the hopes that we would have the first ever over-winter data set from Erebus. Nial gave us the scoop.
We had a few hours of good weather the other day, so Clive and I went up to the crater rim to assess the damage. The camera was not running….which was not too much of a surprise since the power had never come back on. All the batteries at the power generation site had exploded over the winter, not quite sure why yet but hopefully we can fix the problem before we leave. Anyway, even if the power had come back on the camera would not have. It looks like there were some crazy winds at the summit this year – the tripod mount for the camera (which is a 5mm stainless steel bar) had been bent out of shape, allowing the camera to be rotated around by the wind. This broke the power cable to it and meant that it wasn’t pointing at the lake anyway! It wasn’t all bad news though, the camera had worked perfectly up until the power went off (in late April) so we have over 3 million lovely images of the lake (which is more than all the other field seasons put together), and when I restored power to it it started up fine. The lava lake looks much the same as ever, a bit bigger than last year perhaps. There are a few fresh bombs around the summit, but we haven’t witnessed any big explosions yet.
Nial and the rest of the G-081 team are “on the ice” at McMurdo base, Antarctica patiently awaiting a helicopter flight up to the camp on Erebus volcano. Bad weather and an early Thanksgiving celebration on the base have kept the helicopters grounded and the crew stuck in town. Another attempt is scheduled for this evening. in the meantime, Nial sent over some pictures taken close to the nearby New Zealand Scott Base.
“Last night we drove over to Scott base (which is the New Zealand base just over the hill from McMurdo) and took a hike out in the pressure ridges. These are the “wrinkles” in the sea ice formed where the sea ice meets the Ross ice shelf. So it’s a combination of big ice towers, and depressions flooded with sea water. The weather had finally started to clear and it was really beautiful (a few photos attached – they don’t really do it justice though). There were lots of seals out on the ice too which were fun to watch…..well actually they don’t really do much, just lie in the sun. I think I would make a good seal.”
It was touch and go for the Erebus crew this year. Canceled, uncanceled, canceled again, and now, finally, the field season is a go for team G-081 heading to Erebus volcano, Antarctica. Access to Erebus is through the largest base in Antarctica, McMurdo, which is run by the Americans. Our Cambridge crew get to the volcano via a collaboration with New Mexico Tech located in Soccorro, NM, USA. They’re funded by the National Science Foundation. The US government shut down meant that this year’s field season almost didn’t happen. At one point, the NSF even issued a press release claiming the Erebus work had been shelved. Finally, after much confusion, our team got word that they were clear to head for the ice and up to the camp on Erebus.
Did Our Camera Survive the Harsh Antarctic Winter?
Volcanofile Nial Peters has been on pins and needles all southern hemisphere winter — he left an infrared camera perched atop the rim of Erebus, pointing at the lava lake that sits in the Erebus crater. Details of the specially designed camera system are in a paper now open for discussion in the journal Geoscientific Instrumentation, Methods and Data Systems. The crew left the camera with the hopes that it would survive through the entire winter season. If so, we’d have the longest data set from Erebus ever. The camera’s power system was registered as working for some months after last year’s field season was over, until one day it stopped. But, that doesn’t necessarily mean the camera stopped running.
“There are a lot of unknowns,” says Nial. “We know the power lasted for as long as it normally does. The power stopped when the sun went down”. Solar power is a main source of energy for the systems at Erebus, which is fine during the 24-hour-a-day sun in the summer months. In the winter, power systems rely on wind turbines. The timing of the shut down, Nial explains, indicates that the wind turbines may be damaged. We haven’t seen the power return since it switched off, but that could indicate a number of things. It could be that the power came back on but that the telemetry, which tells us if we have power, never returned. If that’s the case, the camera could still be running, but we won’t know until we go and have a look ourselves. There is also a seismometer attached to the telemetry system. If that’s damaged, it could simply be a case of the seismometer not registering any voltage even if the system is running fine. Again, we won’t know what happened until someone goes up to have a look.
Erebus Activity Revving Up?
While we were all worrying about whether the Erebus season would be canceled this year, Erebus decided to put on a nice show for us via the our seismic stations. It looks as though the volcano may have entered a highly active phase, and it may even be throwing out volcanic bombs generated by explosive volcanic eruptions from the lake. Seismic data streaming in from Erebus kept us all on our toes. But, again, we won’t know exactly what’s been going on until the team get there and have a look for themselves.
An exciting season lined up…
In addition to all the exciting science that happens on Erebus each year, this year promises to be an exciting one. With the activity gearing up and the possibility of our first winter data set from the volcano, there’s a lot to look forward to! Watch this space for updates from the field!
Somehow, the end-of-the-season post from Nial on Erebus was shoved under a pile of papers on our desk. But now, and not too late we hope, it’s resurfaced. Here is a belated update (from a few weeks ago) detailing the end of the field season on Erebus for 2012-2013. Everyone’s off the ice now and on their way to their respective homes. Here’s how the last few weeks went for Nial:
The season is starting to wind down now with only six of us left up on the volcano. I only have until the 8th January up on Erebus, so it is now a last minute rush to get everything finished off! The new power system has been working flawlessly (well pretty much!) for a few weeks now, and today the last of the old system got removed. The thermal camera system has a few strange bugs in it, which I have so far failed to track down. It is working reliably enough though, and I’m confident that it will continue to record images until the power runs out (or all year, if the wind generators survive).
We have bad weather for the past week, so not much work outside has got done. Yesterday it cleared though, and now it is glorious! The list of things to do has been drawn up, and now that the good weather has arrived everyone is rushing around trying to get things finished. Yeti (a ground penetrating radar robot – see this link) finally arrived yesterday after being delayed for 5 weeks! So the cave team is out late tonight taking radar data at Warren Cave.