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There's a fair amount of evidence to suggest whenever one has two volcanoes that close they are one
volcano. Of more concern were two things: Nabro is much bigger (2218 m at the summit versus 1625
so about 6 times the volume) and Nabro had not erupted in thousands of years. In our limited circle
of vulcanologists no one knew of anything ever published on Nabro even though it was the tallest
volcano in Eritrea. As all fans of volcano statistics know, world-wide 2200 meters is very modest for a
So we fired up KLIPSPRINGER, one of our applications, to see what predictions we could make about
how long the ash cloud would be a problem and where it might blow. As readers know, Puyahue and
several of its Icelandic cousins have caused problems well beyond the borders of their respective
nations. In particular, Puyahue grounded flights in Argentina, Uruguay and parts of Brazil as well as
Australia and New Zealand.
The answer that came back was certainly not what we expected. We usually work our way through
the math, in this case Navier-Stokes equations in different levels of the atmosphere and influenced
by wind so very complex computing, in a single-threaded situation. If things look good, we fire up a
quad core and launch three or six parallel threads. Three because we don't want to completely hog
the CPU and six if there is Hyper-threading. Then if things still look good we unleash the full
problem in the cloud.
But, we'd not really fully tested our ash cloud code and time was short. We decided to trust Azure
and do a little parallelism of our own. While we frantically looked through code and did some
detailed testing, we sent out some preliminary results to a grapevine of geologists under the title
Tsunamis in the Skies with Diamonds. The answers (plural) we had obtained were TWO clouds:
different kinds of particles and different heights and speeds. I doubt very much we'd have achieved
that any time soon (or perhaps at all) without parallelism. One ash cloud goes more or less west over
Sudan (which hardly needs more troubles) and one ash cloud goes east over the Arabian Peninsula -
for now at least mostly missing Yemen.
We were caught on the hop a bit when a friend with the Irish Weather
Service(!) sent along a note that NATO military analysts concerned with Libya
had used infra-red seeing satellites to pierce the ash clouds and determined it
was NOT Dubbi that was erupting, but Nabro, about 15 miles away.
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