Thursday, 10 March 2011

Fire-Tornadoes, Mud Volcanoes and Volcanic Lightning

Today's lesson was, inevitably so, a bit all over the place and so I thought I would take this oppurtunity to write about somethings that have nothing to do with any of the AS modules but that are still quite interesting.

First up is Fire-Tornadoes. I saw an image of a fire-tornado that was seen spinnig over Hungary last week and I must admit that they look pretty cool. I didn't even realise that you could get fire-tornadoes and so I thought I would do a bit of investigation into how they form (sorry, this is another example of how my curosity gets a bit carried away and I may get a little too enthusiastic - hence why I am apologising now!).
Fire-Tornadoes are also known as fire whirls, fire devils and firenadoes and they occur when intense heat and turbulent wind conditions combine and form whirling eddies of air. These eddies often then form a tornado like structure which then picks up burning debris and combustible gases. The structure of a fire tornado consists of a core, a section that is on fire and an invisible pocket of air that feeds the fire. Normally the core of such tornades range from around 0.3 metres to 1 metres wide whilst the height often varies from 15 metres to 30 metres. These fire-tornadoes often occur during wildfires but can also be provoked by earthquakes or natural gas explosions.
Although Fire-Tornadoes normally do not last that long they can be very destructive. The  Great Kanto earthquake which occured in Japan in 1923 produced a fire-tornado. Even though this fire-tornado only lasted 15 minutes it is estimated to have killed 38,000 people. However, due to the fact that fire-tornadoes are most commonly formed by wildfires in forests and away from urban areas, normally many do not realise when they occur and they are not often reported.

Over a week ago now I read an article about mud volcaonoes and how it has now been predicted that the Lusi mud volcano in Indonesia, which began erupting in May 2006, could continue to erupt for another 26 years. Lusi, which is situated in East Java, is the fastest growing mud volcano in the world and since it began spewing hot mud back in May 2006 it has killed 13 people whilst displacing an estimated 10,000 families. In some areas the thickness of the mud is said to be 18 metres deep and scientists from the UK have said that, over the next 26 years, Lusi could expel the equivalent of 56,000 Olympic swimming pools of mud (that sounds like an awful lot of mud!!!).

Mud volcanoes can appear both on land or under the sea and normally occur when underground layers of silt or clay are pressurized by tectonic activity or a build up of gases. They are most commonly found in areas of high tectonic activity or areas that have large oil and natural gas deposits. Although many mud volcanoes occur naturally, it is believed that they can also be provoked by human activity. For example, it is beileved that commerical drilling provoked a Malaysian mud volcano to start erupting and the eruption of hot mud was enough to claim an entire village.

Recently, a mud volcano starting erupting under the sea off of the coast of Pakistan and has formed a new island - however it is not expected to last long and is estimated that it will be washed away within a few months....
Pakistan is home to quite a few mud volcanoes and they are all created by tectonic activity as the Arabian plate is subducting under the Eurassian landmass. Subduction causes rock to melt into magma and this produces heat and volcanic gases which interact with the groundwater. This causes the groundwater to turn acidic which then dissolves more of the rock above into a mixture of mud and hydrocarbons. This mixture of mud and hydrocarbons are then able to seep through faults. It is rare that mud volcanoes, that are found under the sea, can been seen to be erupting above the surface of the sea as they are not normally large enough to do so.

Lastly on my list of things to quickly talk about tonight is volcano lightning. Not all volcanoes produce lightning but some seem to produce rather a lot, like the 1980 eruption of Mount St. Helens which produced a bolt of lightning roughly every second! Apparently there are two different types of volcanic lightning. The first one occurs within the volcanic smoke and ash plume almost immediately after the volcano has stopped erupting. The process that then causes the lightning is similar to normal lightning (I think) as the ash particles within the expanding eruption cloud become charged. The postively and negatively charged particles then seperate out above the volcano and after a charge has been built up around the volcano, it explodes and sends out a bolt of lightning. I found it quite hard to research the second type of volcanic lightning and I got the impression that not a lot is known about it and so I am just going to try and explain the little bit that I found out about it. This type of lightning occurs during volcanic eruptions, instead of shortly afterwards. When the electrically charged magma, ash and rock leave the volcanic cone it produces a continous sparking at the cone summit - I am then making the assumption that lightning is produced but I couldn't find out any more information after this point. There are some amazing pictures of volcanic lightning - especially from the eruption of the Icelandic volcano, Eyjafjallajokull, last year - so here a just a few of them.....

 This is just a brief overview of these three things and I hope that I got most of it right. There are many other examples of mud volcanoes around the world and volcanoes that produce lightning and some of them are quite interesting to read about. One thing, in relation to the mud volcano in Indonesia, that I have been thinking about is, what happens when the volcano stops spewing mud? Will the mud just stay where it is and dry up and then become good fertile land for growing crops or is is going to be too salty or acidic for vegetation to grow on? If anyone knows the answer please comment as I am quite interested to see what the long term impacts of the eruption of this mud volcano are going to be for the local people......


  1. very interesting, have you looked into the cause behind the Lusi eruption? It is possibly the only man made natural disaster (if such a thing exists) and is an example of how unregulated and unchecked mining companies can be very irresponsible and cause significant hazards by themselves

  2. I must admit that, before I spoke to you on Friday, I didn't know anything much about the cause of the eruption and the controversy surrounding it but it sounded very interesting and so I may have to go and do some investigation!