By Dr. Robert Thorson
Iceland’s Eyjafjallajokull eruption is an Earth Day salute reminding humans of their proper place in nature.
“Civilization exists by geological consent, subject to change without notice.” I used this quote from Will Durant only three months ago to interpret the Haiti earthquake. It applies equally well to what’s taking place in Europe this week. Indeed, everything on Earth began, will begin anew and is ultimately governed by Rock, a word so important that it was frequently capitalized in the King James Bible. Hmmm!
Getting back to the Icelandic eruption, and borrowing two familiar lines from Robert Frost:
Some say the world will end in fire.
Others say in ice.
Had they known better, millions of weary, angry and frustrated European travelers would have disagreed. Their world of unencumbered travel ended not with fire, nor with ice, but with a volatile mixture of the two.
The fire of molten magma lay deep beneath the black basaltic rock of this Scandinavian nation. The ice above that rock – a glacier called Eyjafjallajokull – lay beneath a thick fleece of snow. They were separated until about a week ago, when something very ordinary happened.
Molten magma rose upward through the rock to encounter the ice. Meltwater at a temperature just above the freezing point trickled downward to encounter liquid rock at a temperature just above its freezing point. The water flashed instantly to steam, creating gazillions of tiny gas bubbles not unlike those foaming out of a shaken carbonated beverage, and simultaneously took great amounts of heat from the magma. The visible eruption began.
With a carbonated beverage, the bubbles don’t solidify before popping. With a volcanic liquid they do, rising upward into a progressively stiffening foam that finally hardens into tiny glass bubbles. They burst on their way up the throat of the volcano, producing tiny fragments we erroneously call volcanic ash. They are not soft and powdery like the residues of flame combustion. Instead, they are hard, thin, razor-sharp and composed of an almost infinite number of bubble fragments – not unlike the finest fragments from a blown-glass Christmas tree ornament that fell and shattered on the floor.
Given the localized heat and steamy turbulence above Eyjafjallajokull, the “ash” plume rose upward through the adjacent colder air before spreading out. Coarse particles stayed low and fell in whatever direction the local winds were blowing, generally to the south and east. Fine particles, however, rose upward to reach the jet stream, a swift-flowing current of air perpetually heading toward Europe. As the ribbon-shaped cloud moved eastward, turbulence in the horizontal dimension caused it to widen. Finally, back within the lower atmosphere, local winds spread it around until it spanned much of Europe.
Understanding what’s taking place in Europe this week benefits from an understanding of what’s taking place at “Old Faithful” this hour. Yellowstone National Park’s most famous geyser is faithful because it’s simple: something like putting the same tea-kettle on the same stove to boil, morning after morning. Hourly steam eruptions result from a steady supply of geothermal heat and a steady supply of groundwater meeting in an unusually rigged, but unchanging, plumbing system.
Think of Eyjafjallajokull as “Old Unfaithful” because its system is much more complex. The last serious eruption of “Old Unfaithful” sputtered for two full years beginning in 1821. The eruption before that was in 1612.
Scientists and volcano-watchers know that airline travel in Europe exists by volcanological consent, subject to change without notice. They know that the eruption will end when the supply of fire or the supply of ice runs out. What they do not know is exactly when that will occur.
That’s because Earth is in charge, especially on Earth Day.