Author Archives: Tehnuka Ilanko

Erebus science – carbon dioxide and caves

Hut Cave

Hut Cave

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.

Western Crater and Ice Tower Ridge viewed from Side Crater

Western Crater and Ice Tower Ridge viewed from Side Crater – note how the ice towers and the two craters are aligned

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.

Soil probe with attached copper tubes and pump - the yellow tape is to lay out a grid for a different type of measurement with a CO2 flux meter.

Soil probe with attached copper tubes and pump – the yellow tape is to lay out a grid for a different type of measurement with a CO2 flux meter.

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.

Here the accumulation chamber is being used to collect gas in a bag, so that it can be taken back to the hut for analysis on the spectrometer.

Here the accumulation chamber is being used to collect gas in a bag, so that it can be taken back to the hut for analysis on the spectrometer (see below).

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.

Tehnuka Ilanko

Erebus fieldwork – gas sampling

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 campsite at Lower Erebus Hut

Our campsite at Lower Erebus Hut

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.

Ice Tower Ridge, Erebus

Ice Tower Ridge, Erebus

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!

Heroin Tower: Lyra has set up an anchor above the entrance (the small hole into which the ropes disappear). She has already belayed Tobias into the tower, and I’m about to follow. We climb up to the edge and then in, wearing crampons and using ice axes.

Heroin Tower: Lyra has set up an anchor above the entrance (the small hole into which the ropes disappear). She has already belayed Tobias into the tower, and I’m about to follow. We climb up to the edge and then in, wearing crampons and using ice axes.

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.

Crawling around an ice cave in search of a good sampling location

Crawling around an ice cave in search of a good sampling location

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.

Anemometer in front of large gas vent

Anemometer in front of large gas vent

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.

Spot the scientist: Here, my supervisor Tobias is working on some warm ground just above Ice Tower Ridge. He is wearing a Tyvek suit and setting up a sampling system that he has sterilised using isopropyl alcohol.

Spot the scientist: Here, my supervisor Tobias is working on some warm ground just above Ice Tower Ridge. He is wearing a protective suit and setting up a sampling system that he has sterilised using isopropyl alcohol.

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.

Skylight in Hut Cave

Skylight in Hut Cave

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.

Lyra keeps an eye on carbon dioxide levels in the cave

Lyra keeps an eye on carbon dioxide levels in the cave

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!

Searching for a gas vent...

Searching for a gas vent…

Tehnuka Ilanko

Fieldwork preparations in Antarctica

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.

Mr Orange was our unfortunate crevasse-fall victim

‘Mr Orange’ the mannequin, our unfortunate crevasse-fall victim

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!

The other team undertook the rescue of Mr Orange - the person on the ground has self-arrested and is holding Mr Orange's weight while the other anchors the rope that will be used to rescue the mannequin.

The other team undertook the rescue of Mr Orange – the person on the ground has self-arrested and is holding Mr Orange’s weight while the other anchors the rope that will be used to rescue the mannequin.

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.

USAP shuttles getting covered in snow this morning

USAP shuttles getting covered in snow this morning

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.

The sampling setup on a lab bench, with water at the intake end to help us estimate how long it takes to fill the system with new gas

It turns out gas geochemistry is really all about finding the right size of tubing to fit all the other tubing

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…

Two of the three cases full of equipment that are coming up to Erebus with us

Two of the three cases full of equipment that are coming up to Erebus with us

…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.

View from lab window

Tantalising view from lab window

Tehnuka Ilanko

McMurdo station, Antarctica: 2015-16 Erebus field season

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.

Clothing issue in Christchurch: The parka is called a 'Big Red' and identifies us quite clearly as being with the US Antarctic Program. Although other boots are available, I asked for the blue boots as I've used them before (in fact, I haven't used them since arriving in McMurdo). My favourite item is the wind pants, which are both comfortable and excellent against the wind.

Clothing issue in Christchurch. Wind pants are my favourite items: both comfortable and excellent wind protection.

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.

Sea ice from C-17 window

Sea ice viewed from from C-17 airplane window
(Christchurch – Ross Island flight 16 November 2015)

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.

Disembarking the C-17 at Pegasus airfield. Those in red parkas are US Antarctic program participants; those in orange and black parkas are from Antarctica New Zealand, who share our flights

Disembarking the C-17 at Pegasus airfield. Those in red parkas are US Antarctic program participants; those in orange and black parkas are from Antarctica New Zealand, who share our flights.

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!

Ivan the Terrabus takes us back to McMurdo station (and drops the Kiwis off at Scott Base en route).

Ivan the Terrabus takes us back to McMurdo station (and drops the Kiwis off at Scott Base en route).

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.

Looking south from McMurdo towards the continent.

Looking south from McMurdo

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.

IMGP0081

Scott Base viewed from the road to McMurdo. The interesting ice formations behind the base are the pressure ridges formed at the boundary between the sea and shelf ice.

The main reason for the walk, though, was to get outside and find some nice views…

South from Scott Base - pressure ridges in the foreground, where sea ice and shelf ice meet; probably White Island in the background.

South from Scott Base – pressure ridges in the foreground; probably White Island in the background.

…including a first look at Erebus.

Erebus from Scott Base road

Erebus from Scott Base road

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.

Tehnuka Ilanko

Erebus science – thermal imaging

Infrared cameras are a great way to take thermal measurements of a volcano from a distance. A thermal camera has been used at Erebus for several years. There, it provides the opportunity to look not just at changes to heat output, but also at the activity of the lava lake.  Nial Peters, one of the Volcanofiles and a PhD student at Cambridge, has been operating the camera for the past three field seasons and looking at the data from it. Nial first went to Erebus as a field assistant for Aaron Curtis, who we interviewed last season, working in the ice caves – so he knows the volcano well. Here’s his email interview from the 2012-13 field season, telling us about his work.

Volcanofiles: What is a thermal camera?

Nial: Pretty much the same as an ordinary camera, except that the sensor records IR radiation rather than visible. Objects that are radiating a lot of heat show up as bright. Note that is not necessarily the same as saying hot objects show up bright – a high temperature silver object may show up as less bright than a cooler black object!

Volcanofiles: Perhaps it’s fairly obvious why you’d want to use a thermal camera on a volcano, then? What sort of things can you look for in the footage from the Erebus lava lake?

Nial: Well, perhaps not so obvious. Of course you can use a thermal camera to do the obvious things like measure heat output from the lava lake and many people have done such studies in the past. The reason I use a thermal camera is because it is capable of imaging the lake through a far thicker volcanic plume than a normal camera. Even on days when the lake is invisible to the naked eye, you can still record clear IR images. I am not so interested in the actual temperature readings from the camera, I am using the data to look at the surface velocity of the lake as it convects. You can also record the Strombolian eruptions of of the lake and measure things like refill time.

The start of a Strombolian eruption

The thermal camera can reach high time resolutions…

…so it gives a good record of explosions

Volcanofiles: You’ve spent a lot of time building things so that you can collect data with the thermal camera. How do you set up the camera in the field? And what have you been working on these past few months?

Nial: The thermal camera we have does not store images on-board like most cameras do. Instead it is designed to stream images over an Ethernet link, using the GenICam interface. This means that it requires a computer to operate. The first year we used the camera, we set up a microwave Ethernet link to the crater rim and ran the camera from a PC in the hut. However, my goal was to have the camera run year-round and this setup was too power hungry and unreliable for this.

The system this year is totally different. The camera is being controlled by a ARM based single board computer (SBC) (it’s a Blue Chip Technologies RE2 board if anyone is interested) running Ubuntu Linux. I have written some custom control software for the camera based on the open-source GenICam project Aravis.

The camera and its computer (Photo: N. Peters)

The software captures images, does a very limited amount of preprocessing, and then compresses the images into PNG files. The images are stored locally on a solid-state hard-disc. The SBC also runs a server program which can send the images and some environmental data (power consumption, temperature, etc.)  in realtime over the microwave ethernet link (when it is operational – in other words, during the field season) so that we can keep an eye on things while we are here. The whole system is designed to run reliably by itself for an extended period, with lots of error checking and correction built into the software, GPS time synchronisation and a watchdog program to restart the whole system should something go badly wrong.

Nial with the microwave antenna used for transmitting data to the hut.

The weak link in the system is the power supply. In total the camera system uses about 11W, which is generated by a solar array and some wind generators situated 0.5km away (conditions on the rim are too harsh for solar panels and wind generators). An inverter is used to boost the voltage to 230V AC and power is then transmitted up a cable to the rim where it is stepped down and rectified to 12V DC. The whole power system has been replaced this year using low-temperature rated components and tougher cable. Hopefully this will mean that we can sustain power to the rim year round, but this is a challenging environment so we will see!

Most of my work for the past months has been developing and testing the new camera system (both software and hardware). It is probably the most complex thing I have ever made and I am really pleased that so far it has worked flawlessly (over 600,000 images captured so far!).

Mounting the camera on its tripod at the crater rim

Volcanofiles: This is your third season running a thermal camera on Erebus, and there is data from older field seasons too. What have you measured with it in the past?  And what else are you hoping to do with it this year?

Nial: The motion tracking is probably the most important thing that I have done with the data so far. This picks up the periodic behaviour of the lake very well, and shows that the lake has been doing the same thing for as long as we have been measuring it! It also shows the recent decrease in the size of the lake (it is now a quarter of the size it was two years ago). This year will be more of the same, but with a year-round dataset hopefully we can see in more detail how the lake is changing.

Volcanofiles: You’ve had four field seasons on Erebus. Does the novelty start wearing off? How have things changed for you since the first time you were up there?

Nial: Certainly it is not as exciting as it was the first time, but then nothing is, once you have some idea of what to expect. It is still an awesome place to come to though, and I am still thrilled that I get the opportunity to work here.

I guess the biggest change for me since my first season has been the transition from working in the caves to working at the crater rim. I’m still really interested in the work that is being done in the caves, but particularly this year I have not had the time to get involved. Season to season there is always a bit of change as different people come and go, but I suppose that it is more similar than it is different.

Volcanofiles: How’s the season going so far?

Nial: Pretty well I suppose. Everything was up and running in record time this year. Of course no field season would be complete without everything breaking and that has started to happen now with one broken gas sensor, a broken spectrometer and no liquid nitrogen left for the FTIR. But these things are to be expected, most of the equipment is being pushed to its limits here and so some downtime is inevitable. As I already said, the new power system is almost complete and the thermal camera system is working well – I am confident that we will get many more months of data after we leave, even if it doesn’t quite make it through the winter.

Nial with the themal camera in the field

Volcanofiles: Thanks, Nial – we look forward to seeing some winter data from the thermal camera!

When everything’s running during the field season, you can see the most recent thermal camera images on the Mount Erebus Volcano Observatory site here.

Tehnuka Ilanko

Erebus science – 3D imaging with LiDAR

Our next interview is about a long running project at Erebus. Three dimensional imaging through LiDAR (Light Detection and Ranging) terrestrial scanning technology is a useful way to look at changes in the Erebus landscape – within the crater, and around the ice caves. Drea Killingsworth is the latest student to undertake the scanning work, which began with a scan of the Erebus lava lake in 2008.

Drea did her undergraduate degree at Washington State University in Pullman, Washington, and is now doing her Masters’ degree at New Mexico Tech. For the past two field seasons at Erebus, she has been working with Jed Frechette, from the LiDAR Guys in Albuquerque, New Mexico, and with Marianne Okal and Brendan Hodge, from UNAVCO. And not only has she been doing her own fieldwork but, as expedition chef, she has also been keeping the team fed!

Drea in Warren Cave

Drea in Warren Cave

Drea’s project on Erebus has included scanning the lava lake, the main crater, and two ice cave systems: Warren, and Mammoth/Cathedral, both from the inside and on the surface. At Warren Cave, by combining her work this year with previous years’ LiDAR scans and a survey carried out by Aaron Curtis and Nial Peters, Drea can get a detailed image of how things have changed over the last four years.

A 3D image of Mammoth Cave produced from this year’s LiDAR scans (D. Killingsworth)

With several years of lava lake and crater data, it is also possible to find out how the lake surface level has fluctuated, to quantify its surface area, and follow changes in the shape of both the lake and the crater. LiDAR allows us to see parts of the crater that aren’t normally visible when walking around the crater rim.

Jed with the Optech at the crater rim (December 2010)

Volcanofiles: How does LiDAR work?

Drea: The instrument fires a laser (either visible green or near-infrared light), which is reflected off surfaces and returns to the scanner. Using the amount of time it takes to receive the reflection (or backscatter) when it returns, and the known speed of the laser, it is possible to map the point on the surface where the reflection occurs. Thousands of such points (about 50,000 per second) form a point cloud in three dimensions over a ~7-minute medium-resolution scan at each scanner position. In the ice caves, scans from over 40 scan positions throughout the cave are registered together, to form a detailed 3D model of the entire accessible portion of the cave.

Scanning in Warren Cave (December 2011; Photo: D. Killingsworth)

Screenshot while scanning in Warren Cave (December 2011; Photo: D. Killingsworth)

Volcanofiles: Can you tell us about the different LIDAR instruments you use? What are some of the features you have to consider when selecting the right instrument for a particular scan?

Drea: We used three different scanners on Erebus this field season: the Leica Scanstation C10, which has a class 3R green laser (with 532 nm wavelength), the Riegl VZ400 and the Optech ILRIS-3D, which both use near infrared (with 1535 nm wavelength).

All of the scanners have similar accuracy (to < 1 cm) and cold ratings (functioning in 0° C – 40 °C) but, because of the different wavelengths, power capabilities and designs, they have different ranges and fields of view (FOV). The Leica is very useful for cave mapping because it has a wide FOV of 360° x 270° while its smaller range of < 1 m – 300 m allows for manoeuvrability in tight squeezes.

The Leica scanner inside Warren Cave – that green light it its laser! (Photo: D. Killingsworth)

The Optech has a maximum range of 1200 m but a FOV of only 40° x 40°. In the caves we are scanning entire rooms so a large field of view allows us to use fewer scan positions to scan a given area. For the lava lake, we do a series of scans from a single FOV, so aren’t limited by this smaller area. The longer range of the near infrared scanner is needed to reach the lava lake, which is 300 m down from our scan position at the crater rim.

Volcanofiles: In addition to doing scans of the caves, you have been working on combining GPS data with LIDAR scans, and matching surface features to those underground. Has this been done before? Can you describe your instrument setup for us?

Drea: The GPS does not work beneath the ice of the caves because it cannot receive satellite messages. To accurately locate the caves on the slopes of Erebus, we had to set up known survey positions outside the caves on the surface. Four known surface positions were scanned using LiDAR and a traverse was made down through the cave entrance to four more survey positions set up inside of the cave. By combining the exterior and interior scans, the location of the interior points can be extrapolated from the GPS locations of the exterior points.

Entrance to Warren Cave, through which equipment has to be lowered in (December 2011; D. Killingsworth)

This is not as easy as it sounds! Access to the caves is by rappel and all equipment must be lowered by rope and pulley. To tie the scans together, we had to set up the scanner on a level tripod at the edge of the cave entrance and scan down into the cave to hit an interior target, also on a level tripod. The scanner and target then had to be reversed, carefully lowering the scanner into the cave without moving either of the level tripods.

The LiDAR target at the entrance of Warren Cave (Photo: D. Killingsworth)

The now-known exterior and interior survey points are semi-permanent and can be used for later scans to locate the caves in relation to a coordinate system.

Volcanofiles: You’ve spent quite a bit of time in very different Erebus environments. What are some of the challenges specific to your work on the crater, and in and above the caves?

Drea: In the caves, the biggest issue we face is the change in temperature and humidity between the outside entrance and the inside of the cave. On the surface, the air is very dry and the average temperature is -20°C before wind chill. Inside the caves, temperatures are just above freezing and humidity is extremely high, causing problems with fogging of lenses in the scanners as they are moved from cold to warm areas.

These differences can also cause problems in the opposite direction as water condenses and freezes onto the equipment (and the equipment operators!). The ice caves are not formed completely of ice – the floors of the caves are volcanic rock, covered by a layer of decomposing volcanic glass particles from lava bombs. A day of ice cave scanning involves lugging the scanner, tripods, targets and other equipment through tight squeezes, and navigating and levelling equipment by the light of a headlamp.

The lava lake presents a different set of challenges. The scanners are rated to operate down to 0° C -but the average temperature at the rim, before wind chill, can be around -30° C.

LiDAR gear being carried up to and around the crater rim. (December 2010; L to R: Laura Howald, Kayla, and Jed)

We have had to come up with some very interesting make-shift ‘cosies,’ involving everything from hand warmers to garbage bags, just get our equipment to turn on. Wind and cold makes setting up and levelling tripods difficult.

Scanning the lava lake (L to R: the Riegl, Brendan, and Marianne; Photo: D. Killingsworth)

Despite any difficulties, it is such a privilege to be working on such exciting science in such an amazingly beautiful place.

Volcanofiles: Thanks to Drea for talking about her work, sharing her photos, and for the delicious cooking! To finish, here’s another image from this year to show the kind of results she’s been coming up with.

Image of the lava lake from the 2012-13 field season. One of the interesting results of this year’s LiDAR work is finding out the size of those spatter ramparts – they’re over 5 m high! (D. Killingsworth)

Tehnuka Ilanko

Volcanoes and Society – AXA research day (3)

Volcanoes and Society – Part Three

Putting together the ideas about culture and risk that we’d discussed during the day, I started thinking about the elements that give a solid base from which to manage a volcanic crisis.

 

Pre-crisis steps

Baseline education

We talk about baseline monitoring for volcanoes, so that we know what’s ‘normal’ for a particular volcano and what’s not, and can tell when something unusual is happening. However, we also need baseline public education while things are still ‘normal’ – of course, this will help later in managing a crisis. However, equally significantly, it will mean affected populations become accustomed to living with uncertainty– whether that’s not knowing when or what the crisis will be, or whether that’s not knowing how the crisis will proceed.

One thing I often point out when speaking about my work is that the problem isn’t just ‘an erupting volcano’ – if a volcano was erupting violently all the time, we could avoid it. It’s the transition – when and how volcanic behaviour will change – that causes the problem (as well as its effects on the local population, of course). ‘When’ and ‘how’ are difficult to forecast accurately – so perhaps we should consider it the right of affected populations to have access to information that conveys this uncertainty.

Baseline relationships

Another element to establish before a volcanic event is a baseline of relationships to build up trust between the media, scientists, policy makers and the public. As I consider later (and as may seem obvious!) the media can have a strong positive or negative role in how people perceive a hazard and its management. If the media have established contacts they can speak with during a crisis, and if the scientists concerned have experience in communication via the media, then the roles of both are likely to be more positive. From the scientists’ perspective, the media, when taking on this role, would have much to contribute.

Baseline effective policy

There’s an obvious need for government and policymakers to communicate with scientists, in order to (1) have management systems in place for when a crisis occurs, and (2) have reliable, mutually trusting relationships established to support them in working together effectively during the crisis. It is also important to know that the systems that are in place for managing a crisis are effective – and this brings me to the example of Exercise Ruaumoko. This was a program run in Auckland, NZ, about four years ago, to simulate a volcanic eruption. With the exception of the general public – and the lack of an actual volcano – the procedures followed and the parties involved were as they would be in the event of an eruption. Where resources are available, this seems to me the ideal way to ensure that systems would cope. If the general population could be involved, so much the better.

 

Syn-crisis steps

Science-media relationships: does a unified front amongst scientists give the impression of excluding the public?

Among the set readings for the masterclass was a paper describing two different responses to volcanic crises in the 1970s. Without going into the details for each case, one was a response that was less coordinated, with multiple scientific parties disagreeing very publicly. The end result of such a scenario could be that the scientists appear unprofessional and lose the public trust – not to mention that the issue at hand, the volcanic risk, is overshadowed by the media spectacle. The second instance, when I initially read about it, sounded ideal – a unified front presented by scientists, with very limited channels of information going to the public. But the potential for conspiracy theories is huge and no doubt this would lead to much speculation about information being hidden.

Duties of ‘visitors’ vs. local scientists

Another interesting point not discussed in detail during the day, but that was mentioned in the IAVCEI protocols was that of the responsibilities of scientists from different groups working together during a crisis. These include guidelines for visiting scientists during a crisis, such as that they should be there by invitation only, and leave public statements to the local scientists.

 

 

Final thoughts

As a graduate student in volcanology, I found it valuable to participate in these discussions and consider some of the ideas surrounding crisis management early on. At the very least, they are a reminder that our science is very relevant to society.

Tehnuka Ilanko

Volcanoes and Society – AXA research day (2)

Volcanoes and Society – Part Two

Risk and probabilities

In my last post, I wrote about two aspects of culture and natural hazards – about cultural knowledge of hazards, and about the culture surrounding the way we deal with hazards. I mentioned how we may perceive what is ‘acceptable risk’ differently for individuals and groups. In this post, I want to focus on the idea of communicating and determining acceptable risks and probabilities.

Probabilistic risk maps

One of the recurring themes of the Research Day was that scientists are reluctant to give probabilities; to me, Jonty Rougier‘s talk was particularly eye-opening. He proposed an approach of ‘time integrated risk maps’, rather than hazard maps. He argued that risk managers don’t want to know whether a village is in an area that could be affected by pyroclastic flows – they want to know what the probability is that the village will be inundated by a flow within the next five years, the next ten years, and the next thirty years. They can then consider what they could do to mitigate the risk, and see how those actions in turn affect the probability of risk.

Our ‘risk memory’

While talking about various natural disasters, I started to wonder: how long does our ‘risk memory’ last? Someone pointed out that following the 1906 San Francisco earthquake, building construction was kept to rigorous standards for about twenty years – after which it was dropped due to the expense. I wonder how long the new building standards in Christchurch – and those reviewed around New Zealand following the Christchurch earthquakes – will last.

What is the largest risk we can plan for? Can we take largest historical event we know of as the largest possible future event, and how feasible is this? And what if such an event is so large that we don’t know how to plan for it? One speaker told us how, prior to the Tohoku/Sendai earthquake and tsunami last year, despite some evidence of previous tsunami of similar size along the eastern coast, building standards were matched to something smaller – the largest recorded events. But is planning for the largest historic event always feasible? Another disconcerting possibility – what if the largest possible event is a ‘black swan’ event – something so big that it’s beyond our comprehension?

Following on from the idea of using previous historical events to plan the future, how does this change with the human landscape – for example, can a historical record centuries old be reliably applied to the present day?  I’m inclined to say yes, given that matching of observational data and accounts of historical eruptions have been used to estimate the magnitudes of historical events – the impacts of which can be extrapolated to the modern day.

Acceptable risk

I touched on this earlier when I mentioned ‘personally acceptable’ levels of risk, versus what is acceptable when that risk is integrated over a whole group. How can we quantify risk to human life, and determine what is an acceptable level? Perhaps this is not the role of scientists, but it is worth consideration all the same. At the research day, I was intrigued by one speaker’s cost-benefit evaluation for introducing vertical evacuation structures in Japan to mitigate tsunami risk; essentially, what was the cost of the structures compared to the impact of the loss of life in a tsunami, based on the productivity of the individuals concerned? Perhaps it’s ultimately the economics that determine what risk we can prepare for.

Tehnuka Ilanko

Volcanoes and Society – AXA research day (1)

Volcanoes and Society

A masterclass on Volcanoes and Society is exactly the sort of thing I would like, as a student, to have access to – but until May this year, I hadn’t encountered such an event. The AXA– and Cabot Institute-hosted class produced a great discussion about many aspects of how volcanoes and people interact, and made me aware that this issue needs more widespread, public conversation within the volcanology community. Below, and in the next couple of posts, I’ll consider some of the points brought up at the meeting, and hopefully continue the discussion with all of you!

AXA’s fellowships

The AXA insurance group awards fellowships under three categories, one of which is Environmental Risk. Awards are at levels ranging from PhD studentships to AXA Chair positions. Most of my PhD funding at Cambridge is through an AXA studentship, so I was lucky enough to be invited to attend the Volcanoes and Society Research Day and masterclass. This event was tied in with the launch of Professor Kathy Cashman’s AXA chair position at Bristol. It was co-hosted by AXA, Bristol’s Cabot Institute – which conducts research on the theme of ‘Living with environmental uncertainty’ – and the School of Earth Sciences at Bristol.

The reading we were sent as preparation, the discussions during Kathy’s masterclass, and the presentations in the afternoon brought up a lot of topics, so I’ll focus on those I found particularly interesting. Please do comment, as I’d love for this to stimulate further discussion!

 

Volcanoes and Society – Part 1

Cultural knowledge

One of the first ideas to come up during the Research Day was that of cultural knowledge. To me, this is an understanding of the environment acquired by peoples who have been exposed to a risk for many generations. We discussed how this knowledge may not be accessible to newcomers, and how the advent of modern communications and science is happening at the same time as much of this knowledge is being lost. A couple of completely different examples came to my mind.

Ethiopia – 1969 Serdo earthquake

During our field trip in Ethiopia with the Afar Rift Consortium conference this year, we visited the village of Serdo, which had been seriously damaged by earthquakes in 1969. As we looked around the site, some of the locals came and spoke to us – and it turned out that one of them, an elderly man, had been present during the main earthquake.

In Serdo. Those in front, from left: Frances, her interviewee (whose name I unfortunately don't know!), and Jamal. January 2012

Although it was a few months ago now, one of the things he told us stuck in my mind – that the casualties of the earthquake were from the more recent immigrants to the area, who had built out of stone – whereas the inhabitants of the traditional Afari houses were relatively unharmed.

Although I don’t know for sure that the building style is related to a cultural knowledge of historic earthquakes, I’d love to find out whether any link has been shown.

Ruins of buildings destroyed in the Serdo earthquake

Aotearoa-NZ and Maori mythology

A similar example mentioned by Professor Cashman was that of tapu ground in New Zealand – in particular, a possible link between much of the high ground that was tapu and in volcanic areas.  This wasn’t something I’d considered before, and another Kiwi in my office points out that tapu land is often in areas that would normally not be habitable or suitable for farming – such as steeper ground – so there may be many factors influencing tapu. However, thinking of home led me to the oral traditions surrounding volcanoes in New Zealand. In particular, I remembered an example I’d come across long before I became interested in volcanology – that of the 1886 Tarawera eruption.

The ghost waka (canoe) seen on Lake Tarawera, days preceding its eruption, along with a change in water levels of the lake, was a warning of impending danger to local Maori.  As with other volcanoes of Aotearoa, there were legends surrounding Tarawera that clearly indicated the local iwi had long been aware of the hazards it posed – but particularly interesting to me is how the sighting of the waka wairua demonstrates how the events of that time were also being mythologised. We’re now used to thinking of myths as things of a far more distant past. ­­

I wonder whether such traditions have been lost altogether now – either lost with the arrival of newcomers (for example the arrival of Pakeha traditions in New Zealand) or considered less valuable thanks to competing ideas from science. Or have they just evolved? Will we have myths explaining the Christchurch earthquakes, for example, in a few hundred years?

 

My final question on this topic is whether we can still use cultural knowledge as protection from natural hazards. Could preserving traditions, myths, or ways of communicating help to pass on knowledge of the land that was acquired over centuries? My instinct is to say yes – but if a conscious attempt is made to do so, does that increase the risk of those traditions being suffocated by science?

 

Culture, responsibility, and hazard management

Culture surrounding natural hazards can be thought of in another way. One of the papers we were assigned to read compared Icelandic and British responses to the Eyjafjallajokul eruption of 2010, when fine ash in European airspace held up flights for weeks. While large numbers of travellers were affected around Europe, one of the less publicised impacts was on Icelandic farmers – the population of Iceland have also been living with volcanic hazards for centuries, and from my (admittedly limited) reading it sounds like there is a culture of self evacuation and self responsibility rather than an expectation that the authorities will ‘take care of us’.

 

Isn’t there a risk, though, that this could go wrong if people are given personal responsibility but don’t take account of hazard warnings? One of the issues raised during talks by Jonty Rougier was that, for an individual, a high level of risk may remain personally acceptable – but when integrated over a whole population, (hundreds or thousands of people who each feel they are taking an acceptable risk), the overall risk may not be acceptable for the group. Perhaps that’s where one of the tasks I see as central to volcanology comes in – giving people the knowledge to make informed choices and understand why warnings are issued. This means not just expecting a population to heed all warnings from the authorities but also ensuring people have access to information about the hazards and why the warnings are issued.

 

So…over to you! What do you think?

 

Tehnuka Ilanko

Antofagasta – leaving for Láscar

After a few days’ travel north, we are in the town of Antofagasta preparing to drive into the Atacama desert towards Lascar. The region has some impressive geology – and there is hardly any vegetation to obscure outcrops – so here are some of the views from the Pan-American highway as we drove north yesterday.

We aren’t sure yet of how close we can get to Láscar – it will depend on driving conditions and the latest updates from Sernageomin – but are looking forward to seeing the volcano and finding out what we can measure!

Tehnuka Ilanko