Wednesday, September 22, 2010

Magma, Lava, & Tephra



Arching fountain of a Pahoehoe approximately 1...Image via WikipediaSince it is still Happy Volcano week I thought I would describe the different between three terms you might here during your visit to Costa Rica. First of all one that people always ask is what is the different between Magma and Lava?

They are both motlen rock but Magma is located in magma chambers below the Earth's surface and lava is molten rock that has reached the Earth's surface. The tempature of mamga is between 1300F - 2400F and lava is 1300F 2300F very similar. Lava probably comes from the Latin word "Labes" which means to fall or slide which best describes its action when it reaches the Earth's surface.

Now a third fragment you might not be too familiar with but you should know when visiting Costa Rica is Tephra. Tephra relates very much to magm and lava. Lets look at it like this. Lava is to magma in an extusive form what Tephra is to magma in an explosive form. What this means is that Tephra is fragment material produced by volcanos which becomes airborne. This is very common in history in Costa Rica. We always here have coffee crops were destroyed from acid rain and the present Turrialba volcano activity. Ash can travel for miles into the stratosphere and large amounts of Tephra can reflect light and heat from the sun and tempatures on the Earth can drop just from the eruption of a volcano. Now thinking for the last post I wrote at the start of volcano week the Tephra material is a result of what kind of eruption that is very common in Costa Rica? Pyroclastic Eruptions! Very good I can see your learning.  The picture in this blog is not of Costa Rica but I liked it so much I thought I would share...
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