......her flight home has been cancelled because of the Icelandic volcano.

She's just texted me from her sun-drenched lounger beside the hotel's swimming pool (chilled juice to hand, naturally) and as you can imagine she's pretty devastated. 

But on a more serious note, Madame Mole & I were wondering why this particular eruption (Eyjafjallajokull) is causing so much disruption There is almost continuous volcanic activity in Iceland, much of it very spectacular but which does not bring air travel in Europe to its knees.

Is this one on a much bigger scale than the "usual" eruptions in Iceland, or is it that the Jetstream is flowing in a particular direction at this time of year?

Any experts here?

Quoting widescreenforever:

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I don't remember any disruptions in May 1980  for Mount St Helens,  at that time the volcanic ash spread east to south east thru the United States ..

Yes, that was pretty much what we were thinking. I remember the reports that the ash from MSH had spread all over the globe. Perhaps the density of the ash particulates in the air was much less than the current time, or maybe jet engines are more "sensitive" to particlate damage, or maybe even that the aviation authorities are just more aware/knowledgeable/cautious than they were 30 years ago.

the volcanic ash is made of little rocks and when it goes into the jet engines and does not pass through and cools inside the engines and the particles attach themselves and will cause the engines to fail. the ash basically suffocates the engines. that's why the flights are delayed.

I remember Mount St. Helens - when I got out of work and went to my car, all the vehicles were covered in ash. I hadn't heard about the volcanic eruption until I got home so I didn't know what the heck was all over my car. I'm still amazed that the ash traveled more than 2,600 miles and landed on my car.

Those USGS pages are fascinating. There's one section that states:

Interaction with water can cause magmas that would normally erupt lava flows to explode into ash particles, or cause normally explosive eruptions into more energetic eruptions. These eruptions are called phreatomagmatic eruptions........

I think that Eyjafjallajokull is in a glacier region. Perhaps that would explain the huge amounts of dispersed ash?

And it seems that I was correct in surmising that the aviation authorities are more cautious these days.

Ah well, Sis will just have to show some of that "British stiff upper lip" and go back to the pool.....at least for today; she said that she wasn't sure whether the hotel had any spare rooms for the rest of the week.

Quoting tweeter:

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Trivially, i remember the next season Washington apples after the MSH blew out were outstanding.  Almost 30 years later and still the best apples i've ever tasted.  I think the ash gets much of the credit.

That's why Japan's Mandarin Oranges are so Superior to China's as the Volcanic soil is great food for the Oranges in the shadow of Mount Fuji ..

My dad was stationed at Ft. Louis when MSH blew, the ash that hit us had traveled around the world.

He took me and my brother as close as we could get before they closed the roads leading towards it.  The ash plume raising up was damn impressive and there was a thick layer of ash everywhere.  We took a jar of the ash home and it was quite fine once it dried out.

Quoting Katatonia:

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This is definitely bad news, but let's just hope a supervolcano like Yellowstone (which is very much alive) doesn't erupt within our lifetimes...which would be many, many magnitudes more severe.

if it did erupt then there wouldn't be many more lifetimes
http://en.wikipedia.org/wiki/Supervolcano

think extinction..