TODAY   |  April 16, 2010

Understanding volcanoes and ash

After 200 years of dormancy, Iceland’s Eyjafjallajokull volcano is creating quite a stir. NASA scientist Tom Wagner breaks down the composition of volcanic ash and explains how destructive it can be.

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This content comes from Closed Captioning that was broadcast along with this program.

>>> for more we turn to a nasa program scientist who studies the world 's polar regions . tom, good morning. let's do volcanic arab cloush clouds 101. people say wait a minute , people fly through cloud clouds all the time. what's actually in this cloud if.

>> little fine bits of rock. think of flour being thrown up into the air in your kitchen but it is actual rock particles. it is so abrasive it can screw up airplane engines . what happens is when a volcano erupts and the magna hits the ice, it will literally explode. think if you shook up a soda can and popped the top, the gas involved in that soda can strays out. same thing happens with a volcano .

>> there are a lot of active volcanos around the world so this a xhor common occurrence, the grounding of aircraft in certain regions than we realize?

>> it is definitely. you have hundreds of volcanos in the north pacific , the routes people fly to asia all the time. every year few of those volcanos erupt and air traffic is redirected because of that.

>> we can see with the naked eye very easily this cloud of volcanic ash . it is right there, looks like a really dark, ugly cloud. but do some of these particles of ash fan out in places -- in other words , could a plane get in trouble flying 20, 30 miles from the actual clouds you can see?

>> the biggest problem is this -- it is impossible to tell a volcanic ash cloud from another cloud and it is really difficult for us to track. one of the reasons we use satellite . we don't even track the ash itself, we actually track sulfur that's in the ash so it is hard to see from space .

>> scientists can use all kinds of sensors to try to determine when a volcano might erupt. fast forward -- once the volcano erupts, do you guys have a way of figuring out how long it might spew ash?

>> it is very difficult. we look at the chemistry of the rocks themselves, looking at all the stations on the ground to figure out how the volcano is tilting and using things from space , is the volcano inflating. you put that together but also you learn about the eruption history to try to figure out what's going to go on.

>> we know this ash can cause havoc for an airplane. what happens if this is all through the atmosphere, it clearly has to settle in countries all around the world . what happens when a human being inhales this stuff?

>> there is a few things. first, in this volcano itself in the 1820s it erupted and it killed a lot of local cattle. some people talk about there were some health effects in europe from that. in general i don't think anyone fears health effects from this eruption . if you're right near the volcano there is danger from the eruption itself, gases, and breathing in the particulates over the long term can give you lung problems. right now nobody expects anything from this because it is too dispersed.

>> tom, nice to see you.

>>> now let's get a check