April 15th, 2010

Whoa. That's one serious cloud of volcanic ash.

From http://www.icenews.is/index.php/2010/04/15/iceland-volcano-stops-european-flights/:
The Eyjafjallajokull volcano erupting in South Iceland is having serious impacts on aviation – including the closure of Heathrow, Gatwick and Stansted airports, as well as Oslo Gardemoen.

The ash cloud spreading east has caused all flights to be grounded in Norway, Scotland and northern Sweden and the no-fly zone is expected to be expanded as the day continues. London’s biggest airports will close from midday and delays are already hampering passengers at Manchester, Liverpool, Newcastle and Birmingham.

Flights in North America are not affected, but transatlantic flights are. Ironically, Iceland’s Keflavik International Airport remains open – although there are significant delays on European flights.

The last eruption at Eyjafjallajokull in the 19th century lasted for two years.
And this from the Financial Times' Q&A on the ash cloud:
Where is all the ash coming from?

Iceland’s Eyjafjallajokull volcano started erupting on March 20 and has been gaining intensity. On Thursday a particularly powerful eruption from the central crater sent ash as high as 11km into the atmosphere.

With atmospheric pressure currently high over the Atlantic between Iceland and the British Isles, winds are blowing the ash east and south towards Scandinavia and north-west Europe.

Flights have been suspended over Britain; yet the sky overhead looks clear and blue. Why is this invisible ash so dangerous to aviation?

It is very fine dust, thousands of metres up in the atmosphere, but the tiny particles are extremely sharp and abrasive when sucked into aircraft engines. Hence the flight suspension.

Chemically the ash is made predominantly of silica, the main constituent of sand and glass. Inside a jet engine it can cause serious damage to fan blades and clog surfaces; it may even melt and clog nozzles with molten glass.

Any effect on human health?

Again, not yet. And probably not at all.

But in the worst case, the eruption at Laki in Iceland in 1783 could be an awful precedent. That emitted an estimated 120m tonnes of sulphur dioxide and a vast quantity of extremely fine dust, which caused a persistent haze across western Europe for many months – and is estimated to have killed tens of thousands of people through respiratory and other illness.

If anything like Laki happened now, north Atlantic airspace might have to be closed for months.