Convergent Zones -->West Coast (U.S.A) Edition

Hello readers! It's Isabella reporting again for KWX- marine news with a special story today. Firstly, let me give a shout out to Hinrik VanSvolovets who was so kind and patient with all of my questions about divergent plate boundaries and I hope that my earlier post inspired all of you to further research divergent boundaries. Did any of you find out that in fact, you might just live on one? Im sure you readers are living all around the world but its always fun to personalize science :). Now lets get into more plate tectonics! Today we will be focusing on CONVERGENT PLATE BOUNDARIES . 


So...What the heck is a convergent plate boundary? What's does it do? Where do they occur? Well my mission over the next few days will be to answer those very questions. In order to do that, I'm going to be heading off to the Northern region of Oregon State Coast. (If you want to go find us on GPS were at 44 degrees 52'27.73'' N and 130 degrees 22'29.95'' W)

(http://mappery.com/maps/Major-West-Coast-Volcanoes-Washington-Oregon-and-California-Map.gif)

The reason I'm heading out to the West Coast, is because the Juan de Fuca (oceanic plate) is sliding under the westward moving, North American continental plate and this is called subduction. So basically, one tectonic plate moves under a different tectonic plate, because they are going towards each other instead of pulling apart like divergent plates. Rates of subduction are usually measured in centimeters per year, and the average rate of convergence is the same length (2-8 cm) as a human's fingernails grow each year! Kinda gross... but super cool!

(http://blog.syracuse.com/newstracker/2009/02/Long_Nails_Broken.jpg)

So here I am with geologist Richard Smith here to tell me, and all of you readers, more about convergent plates! I asked Richard to tell us, what happens when the oceanic plate subducts under a continental plate and he said that the continental plate is lifted up and a mountain range is created because the deepest part of the subducting plate breaks into smaller pieces. The Cascade Mountain Range is a perfect example of this! 

(http://www.viewfinderpanoramas.org/gallery/usa/ngardner-rainier.jpg)

The effects of a convergent boundry like this example, is a zone of earthquake activity (shallow around land, but deep underneath). Another effect is the destruction of the oceanic lithosphere because it is subducting underneath the continental plate. Earthquakes will occur over time, and some can be more major than others when subduction happens. Fun fact: We have little earthquakes all the time that we don't even feel!

(http://www.platetectonics.com/book/page_5.asp)

The largest earthquakes Oregon has ever faced happened in 1910 and 1993. The 1910 earthquake was a 6.8 but occurred to far offshore for real damage to be made but the earthquake in 1993 did the most damage because it was right beneath the land area of Oregon, even though it was only a magnitude of 5.9. It is clear that more activity has occurred in Washington, and California. The most recent earthquake in oregon was a 2.7, and this happened Tuesday, April 5th, 2011. 

More to come on convergent boundaries, 

Stay tuned readers!

Reporting for KWX- marine news, this is Isabella.