19 April 2010

10 facts on volcanic ash

What is volcanic ash, and why is it dangerous to people and aeroplanes?

The ash cloud from an Icelandic volcano has had flights in northern Europe grounded since last Wednesday. What is volcanic ash, and why is it dangerous to people and aeroplanes?

  • Volcanic ash is not like the fluffy stuff you find in the fireplace after the fire has died. It is composed of small pieces of volcanic glass, rocks and minerals.
  • Volcanic ash is hard, it does not dissolve in water and is abrasive and corrosive – this why it can clog jet engines, shut off their cooling systems, and cause aeroplane crashes.
  • It is a substance that can spread over incredibly large areas, as it's carried with the prevailing winds. After the explosion of Mt Tambora in 1816, the ash particles in the air blocked out the sunlight in large parts of Europe for most of the summer. It was known as the Year-Without- a-Summer.
  • The danger posed by volcanic ash is directly related to one's proximity to the volcanic explosion. The biggest danger for people close to a volcanic explosion is that of suffocation and fatal burn wounds. It is what killed thousands of people when Vesuvius erupted almost 2000 years ago.
  • People who live close to a volcano can also die from collapsing roofs caused by the sheer weight of the settling ash, which is far heavier than normal domestic ash.
  • Volcanic eruptions (ash and lava) can cause mudslides, floods, wildfires, power cuts and contamination of drinking water.
  • People who have lung diseases such as asthma, bronchitis, emphysema and other chronic lung diseases, can have breathing difficulties when exposed to volcanic ash. Face masks are recommended for people who have to be outdoors.
  • In an area where volcanic ash has fallen, there is usually an increase in traffic accidents, as visibility is poor and the ash can make roads slippery.
  • Eye irritations are common in areas where ash has fallen. The eyes feel as if they have foreign particles in them, and become painful and itchy. It is recommended that children be kept away from fallen ash, and that protective goggles be worn by rescue workers and others who cannot avoid contact with the ash.
  • Minor skin irritations have been reported in areas close to erupting volcanoes.

Volcanic ash can settle on the ground, but it's often carried off into the atmosphere by prevailing winds. The further away one is from the site of the eruption, the lower the danger is. What is frustrating at the moment to many stranded travellers is that they are unable to see the volcanic cloud that has grounded their flights.

But rather that, than coming face to face with its effects thousands of metres up in the air when it has disabled the aircraft's engines.

References (, Centres for Disease Control and Prevention; volcanoes.

(Susan Erasmus,, April 2010)


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