Volcanic Activity

This off-topic post is in the category of trivia.  I do not really have a geology category because this is a Botany blog.  However, it is also a blog of whatever I am interested in at the time, so I am sharing some things about volcanoes

I was curious about the Icelandic volcano Eyjafjallajokull. ( I do not know how to pronounce that).  I wondered how large a volcano this was compared to other volcanoes.  In an article by Elizabeth Cottrell, geologist at the National Museum of History, I learned that volcanoes are ranked by a bunch of different criteria, but the main one I was interested in is the Volcanic Explosivity Index.  This index goes from 1 to 8 and each number increase is 10 times bigger than the one before.  This is called logarithmic.  So, a 3 volcano is ten times bigger than a 2 volcano.  If you are comparing two volcanoes they are ten times bigger for every number they are apart.  So if you are comparing a couple of volcanoes and they are three numbers apart, then they are ten times bigger for each number, or 10 x 10 x 10 or 1000 times different in size.    On this scale, then,  Eyjafjallajokull started out at a 1 and is now about a 4.  In comparison, Mt. Pinatubo in the Phillipines was a 6.  So that was 100 times bigger than Eyjafjallajokull.

Of course, Eyjafjallajokull is getting a lot of press due to its location and the fact that the ash cloud disrupts air travel for much of Europe.  A similar sized volcano would not rate much of a mention in an isolated area. 

I was also wondering about that ash cloud and why it is so bad to fly in an ash cloud.  I learned that jet engines draw in a tremendous amount of air and so little particles like ash can be very abrasive on the engines.  Not good for jet engines at all.  The reason you cannot fly under the ash cloud, it that the heavier particles are constantly falling down to earth under the clouds.  You may be able to see under the ash cloud, but there is still plenty of gritty ash falling down that would get into the jet engines. 

I also wondered if the ash would block the sun and reduce global warming or make crops fail in the ash plume area.  The answer is no and yes.  It won’t really reduce global warming but in areas shaded by the volcanic ash cloud plume there have been occurences of crop failures.

The year without a summer, was 1816 and it was caused by a big volcano erupting and shading the earth with ash along with a reduction of light from the sun (the Dalton Minimum).  It was actually a series of several big volcanoes from 1812 through 1814, four of which had VEI of at least 4.  Then, with the atmosphere primed with dust from these volcanoes, Mount Tambora erupted in 1815 with a VEI of 7.  People reported seeing red snow, sunsets and a persistent fog.  Crops failed or were damaged by frost in the summer of 1815 causing localized famines, disease outbreaks and rainy weather in the northern temperate climates.  Areas of the earth that are tropical reported frosts and crop failures.  So, in comparison, the Icelandic activity taking place is pretty minor.  Interesting reading about both topics in the links below.

http://www.smithsonianmag.com/science-nature/91838474.html

http://en.wikipedia.org/wiki/Year_Without_a_Summer

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