Hey kiddos : )
Haven't been writing for a while but it's just because of all of this travel from Tibet to Saint Vincent (13°11'N, 61°15'W). It's been really sad having to say goodbye to Angie and Gleb, they were fantastic guides for our trip in Nepal. Now, while in Saint Vincent, we have two guides named Marty and Jill. So far they have taught us that Saint Vincent is part of an island arc in the Caribbean. They said that Saint Vincent is at a subduction boundary between two oceanic plates. When two oceanic plates converge, they are accompanied by an arc of volcanic islands on the overriding plate. Here, the oceanic crust of the South American plate is being subducted underneath the Caribbean plate causing a total of seventeen active volcanic islands and many earthquakes!
Historically, in 1839 and 1843 there were two megathrust earthquakes. It is unknown how large these earthquakes really were. Megathrust earthquakes are at subduction boundaries and can exceed 9.0 magnitude! That's HUGE! More recently on August 7, 2011 there was a 5.2 magnitude earthquake just off the coast of Saint Vincent.
Also, the volcano La Soufrière is right here on this island! La Soufrière is an active volcano and also the highest peak here in the island country of Saint Vincent and the Grenadines. Volcanoes form at subduction boundaries because the magma rises when water is released into the mantle. The release of water is called "dewatering" and lowers the melting point of the overlying mantle rock, which then undergoes partial melting and due to it's lighter density, rises. The latest eruption was in April of 1979. There were no casualties due to advance warning. There was an eruption on May 7, 1902 which killed 1,680 people (yikes!).
Wow, all of that information was a mouthful! I have to go for now because we're going on a little hike to get closer to this incredible volcano!
Talk to you later!!
- Kathy
(The first photo is of me and Leah relaxing on the nice beaches of Saint Vincent : ) The second photo is one I just took from where we're standing right now of La Soufrière! The third photo is showing how a volcano forms at a subduction boundary. )
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| http://en.wikipedia.org/wiki/File:Soufriere.jpg |
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| http://en.wikipedia.org/wiki/File:Destructive_plate_margin.png |