THE CHINGCHOK Hunter
You would have to be living under a rock (or a volcano!) to not know about Eyjafjallajokull - pronounced EYE-ya-fyat-lah-YOH-kuht and means "island-mountain glacier" in Icelandic - the Iceland volcano that, at its peak, spewed huge amounts of ash into the atmosphere, grounding much of Europe's air travel. Today we will explore volcanoes, the effect of the Eyjafjallajokull eruption on global air travel and its dangers to aircraft.
View of the Eyjafjallajo¨kull volcano billowing smoke and ash during an eruption on April 17. The massive volcanic ash clouds from Iceland shut down European airspace and hobbled flight connections worldwide for millions of people and cost the air transportation industry billions of baht in losses. AFP
What is a volcano?
A volcano is a break in the Earth's surface that lets molten rock, ash and volcanic gases escape. Volcanoes are active, dormant or extinct. There are approximately 550 active volcanoes, and on any given day there are about 10 volcanoes erupting somewhere on Earth.
The typical cone-shaped structure of a volcano is called an edifice. At the top and centre of the edifice is the summit crater, from which a central vent runs down into a magma chamber. The edifice is made from an accumulation of lava flow, ash and rocks, known as pyroclastic material. Lava and pyroclastic material build up in layers around the summit crater into the classic cone-shaped volcano.
In addition to the central vent, the conduit, and the summit crater, there are often side branch vents that stem from the central vent. They cause flank eruptions on the side of the edifice. These branching pipes can often create their own cones, known as parasitic cones, which are similarly formed as a result of the deposit of lava flow.
Other fractures on the sides of the edifice are breaks where volcanic gases escape, and these are known as fumaroles. The gases that are given off from volcanoes are predominantly water vapour, in addition to carbon dioxide and sulphur dioxide. Sulphur dioxide can condense in clouds and react with water vapour to form acid rain. Traces of toxic gases are also emitted, including hydrogen sulphide, hydrogen fluoride and sulphuric acid, all of which can be extremely harmful.
Volcanoes predominantly occur on and around tectonic plate boundaries. Interestingly, they don't form where plates slide against each other. They are only found where plates are moving towards each other - known as convergent plates - or when they are moving away from each other, known as divergent plates.
When plates are diverging, magma moves up into the lithosphere to fill the void where the plates are parting. This type of volcanic production happens in the mid-oceanic ridges, famously in the mid-Atlantic ridge, where these volcanoes are producing lava that solidifies and produces new oceanic crust on the sea floor. For this reason, it is known as spreading centre vulcanism.
Iceland lies on the mid-Atlantic ridge, where one tectonic plate is moving west and the other is moving east. This has made Iceland a vulcanologist's dream, causing a rift through the centre of Iceland in the form of volcanoes.
With Eyjafjallajokull, the magma has built underneath the crust, causing enormous pressure, so much so that there have been thousands of small earthquakes at the epicentre of Eyja-fjallajokull over the past few months. An eruption was inevitable, but the impacts of this eruption were unforeseen.
Diagram of a typical gas turbine jet engine. Air is compressed by the fan blades as it enters the engine, and it is mixed and burned with fuel in the combustion section. Abrasive volcanic ash can enter a jet engine and cause it to shut down. Ash can also make a windshield opaque. JEFF DAHL
At only 1,666m tall and having a tiny diameter of just 3km to 4km, Eyjafjallajokulll is not much to look at. It has a haphazard eruption history. Eyjafjallajokull's first recorded eruption was in the year 920, followed by subsequent eruptions in 1612, and several others between 1821 to 1823.
During that two-year period, its many eruptions melted glaciers in the local area. It erupted twice in 2010, first on March 20 and most recently on April 14.
The April 14 eruption caused billions of baht in losses to the airline industry, with consequential loss of trade and exports for a multitude of other companies.
In Iceland, there was a blanket of ash many centimetres deep, and the skies below the plume were dark for days. Cars and houses were covered, and there was a serious threat to livestock and crops.
The volcano lies beneath a glacier. Because of the resultant pressure on top of the erupting volcano, a lot of the ash has spewed high into the atmosphere, where for several days, it posed threats to aeroplanes.
Dangers to aircraft
The ash may become suspended in the "fly zone" in the atmosphere. If sucked into a jet engine, the ash may cause engine failure. (See jet engine diagram, below.) On aeroplanes with only one or two engines, this consequence leads to a great risk of crashing.
A plane's fuselage may also suffer substantial damage because, due to the speed at which most planes fly, they essentially get sandblasted by the abrasive ash particles, which can also make the pilot's window completely opaque and cause the plane's lights to diffuse.
In such a situation, the pilot and co-pilot are unable to see outside and have to rely on the electrical equipment. But damage may have already been inflicted on the electrical system in the process. The point is, the threat is real, the dangers are substantial, and that is why European air traffic was brought to a standstill.
Volcano ash: Tiny
Lessons from history
Many planes that have flown through volcanic ash have suffered extensive damage. Some developed engine failure. In 1989, a KLM flight flew through the ash from the Mt Redoubt volcano. In under a minute, all four engines shut down, forcing the plane to rapidly descend. Thankfully, the glass shards (see black and white inset, above left) dislodged from the affected engines, and the plane made a successful emergency landing.
British Airways Flight 9 encountered ash from Mount Galunggung when flying over the Indian Ocean off Indonesia in 1982. Again, all four engines failed and the pilot was forced to fly the plane as a glider. Fortunately, once the plane descended out of the ash cloud, the captain was able to restart the engines, although one of them failed again soon after that. This allowed Captain Eric Moody to land in Jakarta, just as all four engines again failed!
The calm Captain Moody is responsible for one of the greatest, and possibly the most understated, quotes ever: "Ladies and gentlemen, this is your captain speaking. We have a small problem. All four engines have stopped. We are doing our [best] to get them under control. I trust you are not in too much distress." What a flight!
Next to the Eyjafjallajokull volcano is another named Katla, which has a crater of about 10km in diameter. History has shown that eruptions of Eyjafjallajokull have often preceded eruptions of Katla, which is more active and powerful and has a larger magma chamber.
If Katla decides to erupt any time soon, who knows when travellers will be able to fly home?
Dave Canavan has an MSc in Behavioural Ecology and is the Head of Secondary at Garden International School. Dave is fascinated by science and loves animals, especially the dangerous kind! Contact Dave at email@example.com .
About the author
- Writer: David Canavan