## On the geology of Prometheus

Contrary to the advice of pretty much everyone that has seen it, I went to see Prometheus at the weekend. A big reason for going was that I knew they had filmed part of it in Iceland. I had seen the film crews when I was working in the Hekla area last summer and I was curious to see how it looked on the big screen.

In the film, a spaceship lands upon the black rocky surface of a distant planet. The door opens and the crew drive off across the dusty waste to the alien base, with huge mountains towering above them on all sides.

### How much of this is Iceland?

Futuristic all-terrain vehicles race across the dusty landscape of a distant and unfamiliar planet. Steep, dark peaks rise menacingly in the background.

Only the soil is Iceland. A jagged lava flow (aa, or slabby-pahoehoe) covers the floor of the valley, and has since been partly-buried by repeated eruptions of ash and pumice from Hekla.

Everything above the flat plain is computer trickery.

### A real-life active volcano

An old landrover races across the dusty landscape of our very own planet, Earth. Hekla rests peacefully in the background.

A look at real-life Hekla shows the part-buried lava landscape. It looks like the dust clouds from the vehicles that they used in the film were probably real. It looks like the mountains of Iceland, however, were not dramatic enough to make it into the film.

Hekla is one of Iceland’s most active volcanoes, with recent eruptions in 1947, 1980, 1991 and 2000. Each of these began explosively, producing pumice and ash (also called tephra), but quickly switched to producing lava. There have also been much larger explosive eruptions in the past, such as in 1104, which destroyed local farms, and two prehistoric eruptions about 3000 and 4000 years ago which covered most of the country in ash. Ash grains from these eruptions can be found in Scotland and Scandinavia.

When Googling an image for this post, I came across an article on Alien Prequel News reporting that the Prometheus crew had also been filming in north Africa and the Middle East. It seems that the distant mountains, with their horizontal sedimentary layers, are sandstones from Wadi Rum, Jordan.

The Science Punk blog has a nice article (The Science of Prometheus) highlighting the logical flaws and plot holes of the film. There are many, including the one that annoyed me the most: how did the facehugger grow to giant size with no obvious food source?

See a bit more of Hekla, including the huge scale of the prehistoric eruptions, in a post I wrote about them during my fieldwork last year.

Categories: Uncategorized

## Insight into climate debate at the Volcanism and the Atmosphere conference

Last week was the American Geophysical Union (AGU) Chapman Conference on Volcanism and the Atmosphere in Selfoss, Iceland. It covered topics such as explosive eruptions, satellite detection of volcanic ash, aviation hazards and climate modelling. Unlike larger meetings, where sessions run in parallel like the stages at a music festival, all the presentations happened in one room and everyone went to all of them. This way, instead of sticking to the geology sessions (normally filled with pictures of hammers in exotic locations), I saw a lot of talks from other fields. These included a lively debate about how the effects of volcanic eruptions are preserved in the tree ring climate record, which is the subject of this post.

### Live tweeting from the conference

Much of the conference was reported live on Twitter.  You can find the conversation by searching for the hashtag #AGUVolcAtm.   After the speakers have agonized over their presentations in order to fit them into the 15 minute time slot, it’s fun to see them subsequently mashed into less than 140 characters by the audience. There are also 300 word summaries (abstracts) of the presentations available online here.

### Volcanic eruptions and climate

The connection between volcanoes and climate is a result of the gases produced during eruptions.  These include sulphur dioxide and carbon dioxide. It is the sulphur dioxide (SO2) that provides the main influence on climate, as it reacts in the atmosphere to form sulphuric acid aerosol (H2SO4). An aerosol is a suspension of tiny solid or liquid particles in a gas. The sulphuric acid particles reflect incoming radiation from the Sun back into space. If the gas is injected into the stratosphere, the aerosol can remain aloft for years. In this way, large volcanic eruptions cool the surface of the Earth.  Of course, it’s a bit more complicated than I have just explained, and many of the presentations explored the details of the process.

Climatically speaking, volcanic carbon dioxide (CO2) is of minor importance, as the amount of gas that volcanoes emit is dwarfed by human emissions; the average annual global volcanic CO2 emission rate is equivalent to that of a moderately-sized country such as Poland. Other volcanic gases such as chlorine and fluorine have atmospheric effects such as breaking down ozone in the stratosphere.

### Genuine climate debate

A highlight of the conference was a pair of consecutive talks by Michael Mann and Rosanne  D’Arrigo about the signals from past volcanic eruptions in the tree ring record. As a geologist, the exchange gave insight into the topics being debated at the cutting edge of climate science.

That debates exist between climate scientists is sometimes reported as an indication that the foundations of the whole field are unsteady, but this is a misunderstanding of how science works. Arguments over details are common, and indeed necessary to refine our understanding, but often reflect just a fragment of a bigger picture. Two palaeontologists may argue over whether Tyrannosaurus Rex had feathers, but both would agree on the bigger point that they share a common ancestor with the beast.

Here, both Mann and D’Arrigo agree on long term trends in the tree ring record (they must, because Mann’s study uses data produced by D’Arrigo) and that the Earth is warming. But each scientist’s passionate defence of their own ideas shows that consensus on the short term effects of volcanic eruptions on the tree ring record is yet to be reached. Both talks were clear, logical, detailed, and absorbed everyone in the room. This is genuine climate debate and it is fascinating to watch.

#### Underestimation of Volcanic Cooling in Tree-Ring Based Reconstructions of Hemispheric Temperatures

The <140 character version of Michael Mann’s talk is:

.@MichaelEMann: Tree rings miss volcanic cooling spikes. Cold limits growth, but diffuse light from atmos aerosol boosts it. #AGUVolcAtm

It described his recent paper that suggests that tree rings underestimate volcanic cooling. Mann used a computer simulated climate, which he had shown to do a good job of estimating the cooling effect of recent eruptions, to calculate global temperature from 1200-1980 (red line below). It shows clear spikes associated with eruptions in 1258, 1452, 1809 and 1815. He also plotted temperatures from the same period as estimated from studies of tree ring widths (blue line). The spikes are missing. The new study tried to explain why the tree ring data were underestimating the cooling and missing the spikes.

Modified version of Figure 2d from the paper by Mann and coworkers published in Nature. Click to visit the journal.

The tree ring width data came from forests that are so high up mountains or so close to the poles that the trees are clinging on to life at the very edge of where trees can survive. The growth of such trees has been shown to respond more to temperature changes than to other effects e.g. rainfall. Mann and colleagues used equations describing tree growth at different temperatures to predict what the trees would record given the temperatures in the computer-simulated climate (green line). They included a threshold temperature below which growth stops, a description of how diffuse light caused by atmospheric aerosols can help trees grow, and random local variations in weather conditions.

The result is that the recorded cooling is reduced and, because the no-growth threshold resulted in some years with missing rings, the cooling appears delayed relative to the eruption. The calculated tree rings now show good agreement with the measured ones, leading Mann to conclude that his equations are describing real effects.

#### Volcanic Signals in Tree-ring Records for the Past Millennium

Next, Rosanna D’Arrigo took to the podium in defence of dendrochronology (tree ring dating) and launched into a point-by-point rebuttal of a number of Mann’s arguments. In 140 characters, it goes like this:

D’Arrigo: BOOM! Tree ring widths aren’t as good as density and diffuse effect was measured on different forest type to rings. #AGUVolcAtm

Her main point was that Mann’s use of tree ring width data was inappropriate, because tree ring width data are best suited to measuring longer-term trends in temperature. To look at volcanic cooling spikes, they should have used tree ring density data (maximum latewood density: MXD), which is more sensitive to short term changes. She described a study by Briffa and co-workers that picked up the cooling following the Tambora eruption in 1815. Mann had not mentioned this study in his paper.

D’Arrigo said that the diffuse effect was recorded in forests with a thick canopy, which is unlike the areas where the tree rings were measured. She also pointed out studies showing the trees can grow at temperatures below Mann’s threshold, and that the missing rings were less common than he had suggested.

### The discussion continues

D’Arrigo and her fellow dendrochronologists have prepared a formal response, so the debate will continue, in full public view, in the pages of scientific journals. At the meeting, it spilled over onto Twitter, with Mann agreeing that tree ring density (TRD) measurements are better than widths (TRW), but that “TRW dominate tree-ring temp recons”. Unfortunately, tree ring density data is more difficult and expensive to collect.

From the sidelines, it doesn’t seem that the scientific problems are so serious. In time, more density measurements will be collected and the reconstructions will be improved.  Meanwhile, Mann’s ideas can be tested further and accepted or discarded depending on how well they stand up.  The real heat of the argument appears to result from Mann’s failure to emphasise that that tree rings CAN measure volcanic cooling spikes.  His study used tree ring widths because the data were most abundant, even though better methods exist. In the wider media, this made tree ring dating sound less useful than it is, which understandably annoyed the dendrochronologists.

### Other highlights in 140 characters or less

Here are Twitter-sized summaries of some of the other talks at the meeting:

• .@volcanofile: tropospheric volcanic sulphate -> whiter clouds -> global cooling. Better estimates of past emissions needed. #AGUVolcAtm
• Alan Robock, Rutgers: 2011 eruption of Nabro, Eritrea, was largest sulfate producer since 1991′s Pinatubo. #AGUVolcAtm (sent by @alexwitze)
• Foelsche: GPS signals between satellites bend as pass thru atmosphere; temperature controls bending -> can calculate atmos temp. #AGUVolcAtm
• Foelsche: Now we need a big eruption to see if we can detect the effects. #AGUVolcAtm
• Thor Thordarson: 560 cubic km of magma erupted in Iceland in last 11,000 years, since ice age ended. (That’s a lotta magma.) #AGUVolcAtm (sent by @alexwitze)
• Miller: Baffin glaciers retreating -> 14C-date newly uncovered moss -> shows rapid lowering of snowline in 1450s -> LittleIceAge #AGUVolcAtm
• Lavigne: named the 1257 (1258) ‘mystery’ #eruption but can’t reveal name due to ‘embargo’ I suspect … #AGUVolcAtm (sent by @volcanofile)
• Lavigne misunderstands journal embargoes. Nature & Science v clear. Talks allowed. http://bit.ly/qD1lt3 http://bit.ly/KXcqEo #AGUVolcAtm (sent by @alexwitze)
• Prata: If ash conc < 200 microns/m3, can’t really detect w/satellite, but that’s OK b/c it’s not that dangerous to planes. #AGUVolcAtm (sent by @alexwitze)
• Prata: #Eyjafjallajokull yielded some 10 sci papers per teragram of ash emitted. #AGUVolcAtm (sent by @alexwitze)
• Krueger: Strong eruption -> increased winds in Southern ocean -> limits transport to Antarctica -> reduced sulphate in ice core. #AGUVolcAtm
• Elkins-Tanton: Siberian Traps magma chambers in hydrocarbon+evaporite basin -> adds extra S+Cl+F. To 3000000km3 basalt! Nasty! #AGUVolcAtm
• Brian Toon: ‘noctilucent #clouds after large #eruptions could indicate that water was injected in stratosphere’ #AGUVolcAtm (sent by @volcanofile)
• Graf: ‘romantic sunsets after big #eruptions … Need to watch birth rates … with implications for geo-engineering’ #AGUVolcAtm (sent by @volcanofile)

### Other reports from the conference

Categories: Uncategorized

## Happy Anniversary Grímsvötn

Yesterday was the first anniversary of the 2011 eruption of Grímsvötn.  Despite being the largest eruption in Iceland in 50 years, the day passed without much fanfare as the eruption had a relatively small impact compared to a certain other eruption the year before.  To understand why, read my post from the second anniversary of that one: An Icelandic eruption 100x more powerful than Eyjafjallajökull.

In this post, I want to point out the interesting effects that wind patterns had on the tephra dispersal from the Grímsvötn eruption, and to update you on the analysis of the samples.

### Where to go: Greenland or Great Britain?

The US National Oceanic and Atmospheric Administration (NOAA) have a webpage where you can have a go at running their HYSPLIT atmospheric dispersion model.  This uses information on wind speeds and directions to predict where particles in the atmosphere will travel.  It works in forward or in reverse, so if you smell a bad smell, you can find where it came from and if you make a bad smell, you can see where it is going to go.  Except on a global scale.

The Grímsvötn 2011 eruption was interesting, because the final destination of the erupted material was controlled really strongly by the height that it reached in the plume.  Check out these two plots for comparison:

#### Material from 8ooo m goes north

HYSPLIT trajectory for particles released at 8000 m. These do not include particle settling, but give a good idea of wind direction. Material is carried north across Iceland, then across to Greenland.

#### Material from 4000 m goes south

HYSPLIT trajectory for particles released at 4000 m. These do not include particle settling, but give a good idea of wind direction. Material is carried south across Iceland, then across to Great Britain.

#### Where did the tephra go?

The plume from Grímsvötn reached 20 km in altitude, but it turns out that not all of this was tephra.  Much of it was steam and volcanic gas.  To see whether most of the tephra was in the upper or lower part of the plume, have a look at this photograph of the area south of the crater, taken on an monster-truck expedition to the crater last August.

A black sandy desert. This is the tephra deposit from Grímsvötn 2011 on top of the Vatnajökull glacier. All this should be white ice and snow. Click the image to read my post about a trip to the crater last summer.

It is clear from the deposits on the ground that most of the tephra from the eruption was carried to the south by low-level winds and was deposited from the lower part of the plume.  There was very little tephra deposited to the north of the crater, but material from the upper plume was carried carried to the north and was detected over Greenland by satellites sensitive to the volcanic gas sulphur dioxide (SO2).

This complicated dispersal of volcanic material is another reason why mapping volcanic ash clouds is HARD.  The main lessons that were learned are:

• Tephra may not be distributed evenly throughout the full height of an eruption column during a subglacial eruption.
• It is important to get information from the ground and from satellites as quickly as possible to refine computer predictions made during an eruption.

### What happened to the samples?

Some of you may remember that during the Grímsvötn eruption, there was a request from the British Geological Survey for samples of ash collected by the public.  I made a video and wrote a post at the time called An easy way to sample falling ash, and another post showing some of the ash that fell in the UK.  In the end, we received ~130 tape samples from the public and found ash in many of them, particularly ones from Scotland (which is in nice agreement with the particle trajectories above).  The results are being written up, but it will still take months for them to be published formally.  Such is the pace of science.

Thanks again to everyone that sent samples in.

Categories: Uncategorized

## EGU2012 Open Source Software in Geosciences

A splinter session yesterday drew a larger-than-expected crowd to talk about the use of free and open source software (FOSS) in the geosciences.  Those in attendance spanned the range from developers to end-users and the main outcome is that there will probably be a dedicated FOSS in science session at EGU2013.

### A list of FOSS for geoscientists

A lot of the discussion yesterday was about open source software used in computer models (e.g. Glimmer-CISM, a community-written model of ice sheet dynamics).  Examples of more general use of FOSS in geosciences are using GRASS and QGIS instead of ArcMap, Python instead of Matlab, Inkscape instead of Illustrator.  For a longer list and a discussion of the advantages of FOSS, see the post: All the software a geoscientist needs.  For free!

### Showcase of FOSS in research presented at EGU2012

Have you used FOSS in research that you are presenting at EGU2012?  If so, add an advert for your work in the comments (even if it has already been presented).  The list will demonstrate the wide variety of applications for FOSS in the geosciences.  Abstracts for the presentations can be looked up on the conference planner website.

### Topics discussed at the meeting

Much of the discussion was led by scientists who are also developers of the software that they used.  Some of the main themes were:

• The need for reproducibility in science. If people cannot reproduce your results, how can they test if your hypothesis is correct?  This issue was highlighted in a recent editorial in Nature, and it is likely that it will be increasingly necessary to publish code alongside results.
• Logistical issues with packaging code.  Many open source software projects are built different packages from many sources, each with their own schedule of updates.  Sometimes, using a different version of one of these can cause a model to give a different result.  The need was discussed to ensure that older versions of packages are always available so that results can be exactly reproduced.
• Getting credit for your work.  If an open source model is used by the scientific community, it has, in effect, been peer reviewed.  Can a system be developed so that the software itself becomes a citable bit of science, e.g. with a Digital Object Identifier (DOI)? How would this system cope with different versions of the same program?
• Ensuring good documentation.  Scientists often write code for their own use and give little thought to documenting it for others.  If an open-access journal could be created where documentation for a hydrological or climate model could be published, along with an example use case, this would make it easier for others to use the models as well as giving another way of citing the author(s).
Categories: Uncategorized

## EGU2012 broken wifi workaround

There is a problem with the wifi in the conference centre at EGU2012.  Some people can log on, but others cannot.  They can connect to the wireless, but trying to browse the web results in ‘Page not found’ or DNS errors. DNS errors mean that the names of servers are not being correctly translated into the IP addresses they represent.

I was in the second group, until I just met some German dude who showed me a workaround:

1. Connect to the EGU wifi as normal.
2. Open a browser window.  It will try to connect to http://hotspot.egu2012.local/login, but it will fail.
3. Change the server name to the IP address, 172.16.0.1, so that the address becomes:
http://172.16.0.1/login?
4. A webpage will open with a login button.  If you try the button, it will also fail.  Instead, save a local copy of the webpage.  (File, Save Page As…. in Firefox).
5. Edit your local copy, changing all instances of hotspot.egu2012.local to the IP address.
6. Save the changes to your local copy, then open it in your browser.
7. Click the login button, then surf away…

This just worked for me, I can’t promise that it will work for you.  The German lad also said that you might need to redo it each time that you reconnect.  And of course these instructions are of no use to you if you can’t actually get online to read them.

http://hotspot.egu2012.local/login
Categories: Uncategorized

## Science conference posters with Scribus

When you have the right tools to do a job, it is a lot easier to do it well.

Consider making a poster for a science conference. Two software programs commonly used to make posters are Powerpoint and Adobe Illustrator (or Corel Draw). If making posters was shaving, then these would be the equivalent of a butter knife and a surgeon’s scalpel: they might take the hair off, but you will be left thinking that there must be a better way.

This article is a quick-start guide to a free/open source desktop publishing package called Scribus. It’s the poster-making equivalent of an electric razor.  The article contains an example of a simple poster and the original file that was used to make it.  By using these as a starting point, it is easy to make up a poster of your own.  If you need to make a poster for the European Geosciences Union conference next week, then this should give you a head start.

### Advantages of using Scribus for poster making

• It is a desktop publishing program, so it has very powerful features for handling text e.g. wrapping around images, linked text boxes, document-wide font styles, variable line spacings.  You can even control things like kerning.
• It features simple-to-use tools (such as Align and Distribute) for precisely organising layouts.
• Images are stored as links to files, so if you update your figure, the poster is updated automatically.
• The output is a PDF file, which can be printed anywhere and is usually small enough to send by email (5-10 Mb), even for an A0 poster.
• It’s open source, so you can install it on as many computers as you want, wherever you are.

### If bands went to conferences…

The following is a demonstration of what you might see if bands went to conferences.  Click it to see the full, A0-sized, PDF version.  It has been made according to the American Geophysical Union (AGU) poster presentation guidelines, which state that text should be at least 24 point in size to be readable at 2 m distance.

An example poster demonstrating titles, logos, text and image frames, figure captions, references and other features common to science conference posters. Click to see the full-quality PDF version (7Mb).

Scribus_conference_template.sla (right click, Save Link As)

Prettier posters are possible, but this demonstrates what you can make fairly quickly and easily.  With this template, the hard work of setting up the page and defaults has already been done for you.  It has defined style settings for Title, Authors, Section Heading, Figure Caption etc. so it is just a case of replacing the text and images with your own.  It doesn’t take much more work to resize the boxes and personalise the layout, fonts and colours.

The text size used in the bullet points here is actually 36pt size, which is more than AGU require.  I think that most conference posters contain far too much text, so I would recommend keeping the large size.  If you run out of space, then you are writing too much.

### Get Scribus

Get Scribus on Ubuntu Linux via the Software Centre or by running the following command:

sudo apt-get install scribus scribus-doc

Other Linux distributions should have it in their respective repositories.  Windows and Mac users can download installation files from here.

There are some good tutorials for Scribus, including a Quick Start guide, and some video guides on YouTube, such as this one.  It is worth having a look at them, as the range of options when you start can be a bit overwhelming.

Happy poster making!

### Scribus-specific tips

• Use the Story Editor (ctrl-T) to input and edit your text.  Put all your headings and bullet points in the same text box and format them with the Style Manager.  Make sure that you highlight all the text in a paragraph before applying a new style to it as some formatting can be applied to individual characters.
• Make images fit their frames by r-click, ‘Adjust Image to Frame‘ followed by r-click, ‘Adjust Frame to Image‘.  Resize by dragging corners, holding ctrl to preserve the shape.
• Use the Shape tab (r-click, Properties) section to make text flow around your images. You can then position them on top of a box of text and Scribus will adjust everything for you.
• A red cross by your frame means that your text is over-running.
• Use ‘Columns and Text Distances’ in the ‘Text’ section of ‘Properties’ to control offset between text and frame margins.  You might need to enable this option by selecting ‘Show Text Frame Columns’ in the ‘View’ menu.
• Use ctrl-shift-click to access items that are beneath others in the pile.
• Use the Style Manager (dialog labelled ‘Styles‘ in ‘Edit‘ menu) to change fonts, sizes, colours across the whole document.  Local changes can be made in the Story Editor.
• Use Layers (dialog in ‘Windows‘ menu) to separate any background image from the main poster content.
• Align and Distribute is your friend.
• Lock items in place once you are happy with them (r-click, ‘Is Locked‘).
• I used Gimp to fade out the edges of the background image by following these instructions.  I also desaturated the image and increased the brightness to make it less distracting.
• When you open the template file, you will get red crosses where the images should be.  I didn’t include them in the file, in order to save on file size and because they aren’t my images.  If you want to transfer your whole document and all the images to another machine, use the ‘Collect for Output‘ option in the ‘File‘ menu.

### Prettier posters are possible, but this demonstrates what can be made quickly and easily.

Categories: Uncategorized

## An Icelandic eruption 100 times more powerful than Eyjafjallajökull

### Eyjafjallajökull was a relatively small eruption

This month marks the second anniversary of the eruption of Eyjafjallajökull that left millions stranded across Europe, and cost airlines an estimated €150 million a day for six days. But alarmingly, this eruption was relatively small by Icelandic standards. Much larger eruptions, perhaps 200x more powerful, are possible in Iceland and happen as frequently as a couple of times per century.

A webcam image of the plume from Eyjafjallajökull on 17 April 2010. If you think that this was bad, imagine an eruption 100 times more powerful. Source: EWA Blog

Such an eruption would dwarf that of Eyjafjallajökull, pumping out around 10,000 tonnes of tephra (broken up ash and pumice) per second, compared compared to Eyjafjallajökull’s 500 tonnes per second. The tephra-filled plume would speed upwards to over twice the height of Mount Everest and spread over areas the size of whole countries, high above trans-Atlantic air routes. Thunder would boom as powerful lightning flashed within it. In the surrounding country, day would be turned to night and hardy farmers with masks and torches would brave the choking air to round up their livestock. The fallen tephra would turn the landscape to a blacky, sandy desert.

Having seen the effects of Eyjafjallajökull in Europe, you can imagine what would happen with an eruption one hundred times more powerful: transport crippled as thousands of planes are confined to their hangers; airports turned to giant refugee camps; riots for tickets at ports and railway stations; panic buying of fuel; rotting mountains of undelivered food; masked youths swarming the gridlocked Champs Élysées as a weakened, blood-red, sun casts its last rays on the Arc de Triomphe. A lone survivor picking through the wreckage of the city to be reunited with his pregnant sweetheart and their quirky-but-lovable dog.

### Grímsvötn

Hollywood and the newspapers have primed our imaginations for such carnage across the European continent, but the reality was not like that.

Yes, I said ‘was’.

We’ve already had an eruption much more powerful than Eyjafjallajökull: the Grímsvötn eruption of May 2011. Everything that I described in Iceland actually happened. Everything that I described in Europe was made up.  As a rule of thumb, ~100x increase in the power (discharge rate) of a volcanic eruption results in a plume ~3 times the size.  At its peak, the Grímsvötn plume reached 20 km, compared to 5-10 km for Eyjafjallajökull during much of the time that European airspace was closed.  The eruption produced about twice as much tephra (~0.7 cubic kilometres vs. ~0.3 cubic kilometres) in a much shorter time (4 days vs. 39 days), so the average discharge rate was around 20x that of Eyjafjallajökull.

Animated GIF of the beginning of the Grímsvötn 2011 eruption. This eruption was up to 100x more powerful than Eyjafjallajökull was when it was stopping planes all over Europe, but caused much less disruption to aviation. Source: Iceland in Pictures blog

The huge disruption caused by the Eyjafjallajökull 2010 eruption was a combination of bad luck (it coincided with an unusually-long period of northerly winds that blew the tephra to Europe) and bad planning (there wasn’t much information on how much ash an aeroplane could safely fly through, so the limits were set at a very low level). The rules were changed, and as a result, it was clear when the Grímsvötn eruption began that it was not going to be a repeat of Eyjafjallajökull. In fact, the disruption in Europe was relatively minor, with just 900 out of 90,000 scheduled flights cancelled. These were mainly in Scotland, Scandinavia and Germany.

The low impact is reflected in the cultural importance of the Grímsvötn eruption, as measured by the ultimate cultural barometer: Google rankings. It was the largest eruption in Europe in 50 years, but a Google search for ‘Grímsvötn 2011‘ brings back just 844,000 results. ‘Eyjafjallajökull 2010‘ gets 4.7 million. ‘iPhone 4‘ gets over 2 billion.

A black, sandy desert. This is the tephra deposit from Grímsvötn 2011 on top of the Vatnajökull glacier. All this should be white ice and snow. Click the image to read my post about a trip to the crater last summer.

In the eyes of the media, Eyjafjallajökull remains the default reference for an Icelandic eruption, but this view is out-of-date. The science and the organisational structures in the airline industry have improved and this is reflected in the lower impact of the Grímsvötn eruption. If the structures and technology that are in place now had been there exactly two years ago, there would have been far less disruption.

### The rules are different now

The new rules for the ash concentrations through which an aircraft can fly make a huge difference to the possible effects of eruptions in Iceland.  The map shows predicted ash concentrations during the Grímsvötn eruption, on 25th May 2011. All aircraft can fly in the blue areas. If an airline makes a ‘safety case’ to the Civil Aviation Authority, they can enter the grey zones and sometimes even the red zones. Whether you can accurately map the difference between the two zones is another story.

Section of map of predicted ash concentrations during G2011. Under the old flight rules, all coloured areas would have been out of bounds. This would have resulted in closure of London airports. Source: Met Office, Crown Copyright 2011. Click image for full plot.

Under the old rules, all coloured areas were no-fly zones. As the cloud moved eastwards, this would have closed airports across the whole UK on the 24th May, and again on the 27th. The whole of the UK.

This means you, London!

To me, this significant point seems to be completely ignored in discussions of Icelandic volcanism. At the time, it was drowned out by claims that the ash cloud was a ‘myth’. That Heathrow airport remained open during Grímsvötn 2011 represents progress in our handling of Icelandic eruptions. Of course, there is room for further progress to be made, and much of this will come through closer linking of satellite data to computer models in order to combine the advantages of these two distinct methods of mapping ash clouds.

### Reality is less dramatic than you imagine

The problem with these imagined apocalyptic scenarios is that they project events that occur in a small region around the volcano onto locations that are much further away. They forget that London is about 1700 km from Eyjafjallajökull. It is a very long way; more than 500 miles and 500 more. Even the Proclaimers would not walk that far. The effects of even the largest eruptions are much less severe at such great distances.

The worse case scenario for Europe is a large flood-basalt type eruption, which would last for months with repeated flight disruptions and the release of abundant toxic and weather-changing gases. The Laki eruption of 1783-4 produced 14 cubic kilometers of lava and was associated with tens of thousands of deaths in Europe caused mainly by heart and respiratory problems.

Fortunately, these eruptions are rare, with only two in the past thousand years, but if one did occur, I suspect that the reality of even this would be less apocalyptic than you might imagine. You would not see whole families cut down in their prime, spluttering and bloody-mouthed. The closest analogy is a heatwave in France in 2003. It killed nearly 15,000 people there, but, to quote The Day Today, most of them were old and would have died soon anyway. This group of people are also the most at risk from a Laki-type event, but unless you worked in a hospital or were unfortunate enough to know one of the victims, the extra deaths may pass unnoticed. Furthermore, this is also a scenario where good government planning could really reduce the impact.

### And Katla rumbles on…

Meanwhile, the media obsession with Katla continues, particularly following increased seismicity over the past year. The truly awesome floods that can accompany Katla eruptions are a genuine concern for Icelanders, but as far as the Europe is concerned, 16 of the 20 Katla eruptions since 920 A.D. that have been measured were similar to, or smaller than, the 2011 Grímsvötn eruption. It is therefore probable that the next Katla eruption will have similar consequences: some flight disruption, mainly in Scotland and Scandinavia, probably for 1-2 days.

Earthquakes per day at Katla since Jan 2011, showing increased activity since last summer. What it actually means is unclear. Click the image for more information.

Erik Klemetti wrote a nice article on his Wired Eruptions blog about how news websites regularly peddle fear of an Icelandic eruption . He said that Katla was the media favourite because it is: “(a) near Eyjafjallajökull; (b) hasn’t erupted in a long time; and (c) easier to pronounce.” One of his readers, Carl le Strange, left a suggestion on how to address this. I think that it is an excellent idea, and a perfect antidote to the hype surrounding the 2nd anniversary of the Eyjafjallajökull eruption.

Sometimes I think they should rename Katla into Lítileldfjallsemmunaðeinstaugarnar, that should really take care of the problem…

[...]

Oh, and that odd name would be in english “Smallvolcanothatwillonlyirritate”

Categories: Uncategorized

## Sounds of the Underground

This is a post that I originally wrote in June 2007.  It contains sound files that let you hear the crashings and rumblings that go on beneath the ground near Volcán de Colima, Mexico.  I’m reposting it today because a) it deserves a wider audience, b) I’m off to map the deposits of the Hekla 4 eruption in Iceland soon and don’t have time to write a fresh post this month, and c) Mexican earthquakes are in the news today.

I hope that you enjoy it.

### Earthquakes in Colima

We had a couple of earthquakes last week. The first was magnitude 5.2 and took place at about 05.30hrs on Wednesday morning. It was the talk of the town the next day, but a healthy dose of tequila the night before had ensured that we slept straight through it. One of the aftershocks came at lunchtime the following day and was quite impressive as it rattled window panes and shook me in my chair. It was a magnitude 4.2, which isn’t huge but the epicentre was only 25 km away so it still felt strong.

Image from http://earthquake.usgs.gov

The people of Colima get rightly scared when the earth shakes. In 2003 there was a magnitude 7.8 that flattened buildings all across the town and killed a number of people. Considering that the extra energy released by each grade on the Richter scale is 10x larger than the previous and that the 2003 earthquake was therefore ~1000x more powerful than the one that we felt, it must have been pretty scary.

### Seismicity as sound

On Friday I discovered how to convert the traces from the seismograms into sound files so that we can ‘listen’ to the earthquakes. Volcano seismologists have been doing this sort of thing as part of their analysis of the seismic signals for ages. They use it to detect changes within the plumbing of volcanoes that may one day be a method of predicting eruptions. I did it because the results sound cool. The sounds produced are not real – they are vibrations of the Earth that have been sped up 50x so that we can hear them with our ear. But you can clearly tell the difference between various types.

Click the images to hear the sounds.

**If you get a taste for seismicity as sound, check out this post on the Highly Allocthonous blog that demonstrates the power of last year’s Japan earthquake.**

#### Earthquake

The trace above is from a tectonic earthquake.  It sounds like a cross between someone slamming a door and the rumble of distant thunder. This is the noise of big slabs of rock grinding past each other in a sudden jerk.

#### Explosion

This trace is from an explosion at the volcano. It is the sound of pressurised gases explosively bursting free from the crater, carrying ash and rock fragments with them. It is easy to hear the energy tail off as the pressure is released.

#### Harmonic tremor

A third kind signal comes from harmonic tremor. It sounds a bit like whale-loving or a broken trumpet. This type of signal is a bit special, as it is thought to be caused by seismic waves travelling within a gas- or fluid-rich conduit beneath the volcano. Different frequencies are amplified or cancelled-out like sound waves in a music instrument. Volcano seismologists use the changing frequencies of the signals to estimate things like pressure beneath the ground.

Categories: Uncategorized

## One year of volcan01010: Best of 2011 and coming up in 2012

This week is the first anniversary of the volcan01010 blog.  With this post, I want to pick out some highlights from 2011, and to whet your appetites for some things to come in 2012.

### Top 3 posts:

The main aim of the blog is to be a source of reliable and easily-understood information on Icelandic and other volcanism.  I also want to showcase the use of open-source software in (geo)scientific research.  Most posts are ‘feature-length’ to allow a deeper discussion of each topic, and I hope that this means that they are worth returning to months after they are first written.

The following 3 posts were among the most popular and give a good summary of what the blog is about:

• Grímsvötn eruption – frequently asked questions.  This post, written at the onset of the May 2011 eruption, explained why the eruption was unlikely to cause as much disruption as Eyjafjallajökull 2010, even though it was bigger.  The post got lots of hits because is was quoted by a number of news websites.  It is worth re-reading, because the same will most-likely apply to the next Katla eruption.
• Grímsvötn 1 – Crossing the glacier.  In August, I was lucky to join an expedition to the crater of Grímsvötn to study the newly-erupted material.  It was an adventurous journey involving monster-trucks, crevasses and a crazy landscape of ice and tephra.  This post describes the journey and explains what we found.
• All the software a geoscientist needs. For free! This post explains how you can replace packages such as Microsoft Office, ArcGIS, Matlab, Adobe Photoshop, CorelDraw with free and open source alternatives.  Not just because it is cheaper, but because it makes your workflows portable and easy to automate.

Crossing the tephra-covered glacier on the way to the crater of Grímsvötn. Click the image to read more.

### Volcanoes, software tricks and general musings

There were a number of other Grímsvötn posts, explaining how to collect samples of falling ash in the UK and why it is so difficult to map the ash plume from a volcano.  There were also posts about the deposits of the huge Hekla 4 eruption and the massive floods from Katla that make her eruptions so serious for Iceland.  Outside of Iceland, there were videos of lahars at Volcán de Colima and an animation of the globe-spanning plume from Puyehue Cordon-Caulle.

Need to chop/rotate/annotate/join some images in a hurry?  There was a post on ImageMagick to show you how.  There were also general musings on the striking similarity between piles of grain and the shape of mountains and wondering why people insist on using Imperial units to measure babies.

The site now has an archive page, Every post ever, which you can browse other posts that might grab your interest.

### Coming in 2012My home for the summer in Iceland: a VW Transporter T4 Syncro van.

From the end of March, I am off to live in a camper van in Iceland until the late autumn.  I will driving round the country digging holes and sampling prehistoric tephra (pumice + ash) layers.  I will be working with the Icelandic scientists responsible for monitoring their volcanoes, so if there is an eruption from Katla (who is still rumbling) or Hekla or anywhere else then I will be able explain things with the best information, direct from the scientists themselves.

On the computing side, it is a longer-term aim to post an introduction or quick-start guide to each of the programs described in the All The Software post.  The Image Magick post is an example of this.  Many of these will form part of a series called Quit wasting your life with Excel.  Watch this space.

### Subscribe, then tell all your friends

The best way to follow volcan01010 is to subscribe to the RSS feed.  If you’ve never heard of RSS, read this guide.  It lets you keep track of posts that you have read and tells you when a new one is out.  You can also follow me on Twitter (@volcan01010).  This way you get updates with other news and links that I think are cool, but if you follow lots of people then it can be easy to miss announcements of new posts.

Volcan01010 now has 201 followers on Twitter, and in the last year the blog scored 21,679 page views from 10,049 unique visitors in 149 countries (with the vast majority in the UK and USA).  It has passed an important psychological barrier of at least 100 reads per new post, which means that the total time spent reading an article is now more than the time it takes to write!

If you find the blog interesting or useful, then please tell all your friends.  Then tell them to tell all their friends, too.  It’s going to be an interesting year.

Categories: Uncategorized

## A Very Scottish Skyline

Crossed contrails in the sky above Edinburgh this evening, looking south toward the Pentland Hills. Click to enlarge.

In 2014, Scotland will have a referendum to ask the people if they want to become an independent country.  The Scottish National Party will be campaigning hard for a ‘Yes’ vote.  Does that extend to some kind of deal with air traffic control?

Or perhaps it is a good omen ahead of Scotland against England in the 6 Nations rugby this weekend?