Vulcanian eruptions, generally considered as the next step up in explosiveness from Hawaiian eruptions, are very distinct from other forms of activity such as Strombolian as they are related to the emission of mostly ashy pyroclasts and blocks in more voluminous amounts. This is in direct contrast to the incandescent material ejected during Hawaiian and Strombolian events. These events can occur on time-scales of minutes to hours or more. They are generally thought to be caused by the build-up of gas below a cooler plug of material which builds up sufficient amounts of pressure to explosively force the plug of material from the conduit. This then creates a column between hundreds of metres and kilometres high filled with ash and can also lead to the ejection of large metre size blocks. Typically this type of eruption occurs with higher viscosity magmas which don't allow the rapid rise and expansion of bubbles (and hence allow large amounts of passive degassing). This then allows the upper conduit to cool. Of course there are always exceptions and different situations when considering volcanic eruptions!

Where do Vulcanian eruptions they get their name from? No surprises here when I tell you it is from the Volcano Vulcano, one of the Aeolian Island volcanoes which has most commonly exhibits this kind of activity. There are several great textbooks with more information on this type of activity - Volcanoes by Lockwood and Hazlett and of course Volcanoes by Francis and Oppenheimer. I am sure there are more!

I was very lucky that I started my PhD with a large amount of data collected during the summer of 2012. Whilst I was at Mt. Etna in July I was fortunate (I think) to witness the filming of a Discovery Channel episode called - 'Volcano Time Bomb' which was aired in December 2012. I was volunteered to help carry camera equipment up and down from the summit...(for two very nice guys I should add)

Currently, a lot of my work is involved with looking at correlations between various geo-chemical and geophysical signals. Some of these produce very colourful images anyway, but especially so if you make a mistake! This was produced in Matlab. Let me know what you think! Certainly better than some of the artwork you can see, perhaps I will make millions...

YouTube is a great tool if used correctly, but you can find some utter nonsense! I usually try to avoid posting on this kind of thing, however, this video actually confused me greatly and annoyed me as well. Please don't watch it all, it is nine minutes long, watch just a little and you will get the jist. The author states the following in her description: 

To cut a long video very short. The author assumes that these lines flashing up on Google Maps/Earth (whenever the author moves the map) are somehow linked to recent earthquakes and/or a sink-hole because a line may randomly cross a recent earthquake event. They are obviously not. I am no graphics expert, but it seems quite obvious that they are the result of loading or redrawing of the map as it is moved. At which point do we jump to seismic signals, infrasound or Haarp?! In science the principle of parsimony is often referred to: if there are many theories the simplest should be preferred. This is definitely the case here.

The only factual part of this report is that there was a 3.2 earthquake in the Yellowstone area (not really that unusual by the way). Please please please tell me this was an early April Fools joke, unfortunately I don't think it was.

The Icelandic Meteorological Office has raised its aviation code for Hekla from green to yellow. Why have they done this? Well according to this news article, there has been an increase in seismicity, which is unusual for Hekla, although there has been no marked changes in other eruption precursors such as inflation and they further state that there is no eruption imminent. Recent earthquakes can be viewed here. If you are interested in the decision making process of the Icelandic Meteorological Office (IMO) and how they communicate with the public, I highly recommend skimming (or reading thoroughly!) this presentation which is available on their website. From this (if I understand it correctly) I can determine that the alert level has been raised because of an uncertainty surrounding the change in activity, which doesn't necessarily mean that an eruption will occur at all! However, what does history tell us about eruptions at Hekla? The IMO has a list of volcanic eruptions since 1900 on their website and you can see that Hekla features prominently with eruptions most recently in 2000 and 1991, whilst the Global Volcanism Program also shows regular activity . 

If Hekla were to erupt, we can expect the typical activity which has been seen in the past, typified by the photos on the GVP website, a mixture of explosive activity and lava flows. One of the major dangers from an eruption of Hekla is the emission of Fluorine, which the magmas from Hekla seem to contain more of. Inhalation of Fluorine can cause Skeletal Fluorosis (yes I did link wikipedia) and has caused significant fatalities of humans and livestock in the past from eruptions such as the Lakagigar fissure eruption in 1783.  

You can view webcams of Hekla at these two sites: one is a closer view, and the other is at a distance but arguably of better quality. This activity change could show the very early signs of a future eruption or it could also be an anomaly, it is certainly too early to tell at this stage.

Mt Etna, has had a relatively active start to the year. The major focus of this recent activity has been at the South-East (SEC) and Bocca Nuova (BN) craters, indicated in the Google Earth image to the right. This activity has included a mixture of activity types including: strombolian , jetting (Hawaiian type) and ash emissions. This type of activity has been prominent at the volcano over the past few months, particularly in the BN crater (as I was lucky to witness in July). However, the SEC has been relatively quiet for 9 months previous to this recent reactivation. I thought that this would be a good point to briefly discuss the summit of Mt Etna. Despite a very prominent summit area from a distance, Etna has three main areas: the Central Craters (Voragine and BN), the North East crater (NEC) and SEC (and NSEC). The NEC and Voragine mostly emit gas passively. All of these contribute in a different way to the volcanism at Etna and all need to be studied in detail to gain an insight into the complexities of an active volcano.


The first image below shows minor ash emission during the activity from the NSEC on the 20th February 2013. At this time of the year, the slopes of Etna are used for skiing. In certain places you can see white snow poking through a fresh covering of black ash (as a result of the basaltic magma). The ash emissions from the NSEC are clearly separated from a lower area of steam. It is even possible to notice some incandescence near to the NSEC (just below the NSEC) and against the right edge of the image and half way down. Other images below this show much more vigorous activity with the first image on the left showing a clear lava fountain. The image to the right of this shows more clearly the incandescence I mentioned earlier and shows the likely cause of all the steam (the result of lava heating snow)! This could be indicative of a fissure or a lava flow with fast flowing lava allowing it spill up over the edges spectacularly. Although the images are not 100% revealing so I can't be certain.


For a discussion of the causes of strombolian and hawaiian activity please see a couple of my previous posts. Etna continues as one of the most active volcanoes on the Earth and will continue to provide a spectacular show for all of us over the coming months and far off into the future.

I am now approaching a whole five months of my PhD so far and it has been a great experience. It has dawned on me over the past few weeks, how multidisciplinary the field of volcanology is. My own work (so far) has stretched across multiple fields already such as remote sensing, statistics and mathematics, physics and chemistry, all in the pursuit of greater knowledge and understanding of volcanoes. For example understanding the chemistry of rocks allows us to understand how they may behave and act beneath the surface. Then, physics can help us to understand how bubbles move in the magma prior to emission at the surface which is then captured by remote sensing techniques.

This reminds me of something I came across during a lecture on the philosophy of geography during my undergraduate degree in the form of a statement about geography:

Personally I think this is phrase is redundant. Increasingly the focus of research is inter-disciplinary (and it is easier to get research funding if you can prove it!) so I believe it is more of an advantage to have a handle-hold on many subjects/disciplines - be knowledgeable in multiple areas. However, when you delve deeper everyone has their specialty subject area; you could be an expert on climate and volcanoes, gas and volcanoes or the petrology of rocks. I guess this just emphasizes the importance of working with others to combine expertise. Going back to the original statement, 'geography - a jack of all trades or a master of none', in the academic world very few people would define themselves as a geographer, they could be an economic geographer, climatologist, hydrologist or ecologist and you could even subdivide these further! A geographer can be a specialist in his particular area whilst also have a grasp on other areas, whilst not being a master of all of these other areas, furthering scientific understanding means taking a multidisciplinary approach which couldn't be done by the master of just one trade. 

For a few months now Plosky-Tolbachik has been erupting, producing extensive lava flows and it continues to provide us with some amazing photos. I highly recommend having a look at the following site with some truly spectacular images of the current eruption. It may seem that the people are extremely close to the eruption, however, they are about 300 metres away according to the text underneath the pictures, which explains the nonchalant stance of one of the people near to the eruption!

I have pulled one of the photos off the reel and posted it to the right as it illustrates well what I have been talking about in recent posts about gas in volcanic eruptions. You can almost see the shape of the bubble which has burst at the surface by the trajectories of the lava. 

I meant to post this way back in September after my latest field visit to Mount Etna, but never got round to it/forgot! A couple of photos showing how quickly the weather can change on Etna. The day before it was very cold but no signs of snow and woke up to this the next morning. Below is the Pizzi Deneri volcano observatory where I was lucky enough to stay for a week during September.

Needless to say not a lot of work got done on this day and a hasty retreat back down the flanks was made (to where it was nice and warm!). This serves to demonstrate that there are more hazards when working on a volcano than just the volcano itself!

First of all, happy new year! It is set to be a busy one for myself, no doubt involving various volcanic visits which you will all here about.

Today, in my why is gas important series, a brief look at 'Passive Degassing'. This is gas which is released at all times from a volcano, even when there is no eruption occuring. This can also be termed as quiescent. The major gases emitted include Water Vapour, Carbon Dioxide and Sulphur Dioxide (amongst others) and are usually in that order for amounts released.

Monitoring emissions of gas is important as it can inform volcanologists of amounts that are being released and whether these are in a normal range. An increase in emissions could indicate that an eruption is imminent, but a decrease could also indicate the same! It can vary greatly on a volcano basis. For example, an increase in emissions could indicate that a fresh batch of magma has entered the plumbing system with lots of entrained gas (the major driver of volcanic eruptions) and the increased emissions at the surface is showing this. Or there could be a large decrease in emissions, which could indicate that either there is a shortfall in gas supply from depth or that the gas cannot escape. This could indicate a build up in pressure and that a volcanic eruption is more likely. Of course, to make such assessments accurately a detailed history of amounts of gas released is needed to determine the normal behaviour for a given volcano. As with all volcanic situations, a large and unusual change in emissions doesn't necessarily mean an eruption will occur!

How do we measure these emissions? There are a variety of technqiues, those which involve collecting gas from fumaroles or a plume or remote sensing techniques be it via a satellite or more mobile ground-based cameras. Most monitoring is of Sulphur Dioxide due to its ease of measurement. Of course emission of other gases are also important. The eruption of Laki, Iceland released a large amount of Fluorine which is thought to have caused a large amount of disease throughout Europe.