Post by Paddy by Grace on May 21, 2010 14:56:14 GMT -7
news.discovery.com/earth/earth-mentle-crust-alaska.html
A new 3-D model of the mega-quake and tsunami-launching subduction zone in Alaska has uncovered a big surprise: The Earth's mantle there is moving a whopping 20 to 30 times faster than the crust.
So instead of being dragged along for the ride as a slab of crust is pushed under another, the solid rock mantle rock is swirling around the plunging slab like water around a paddle dipped in a stream.
What the models predict are flows up to 90 centimeters per year around the descending slab of crust, said geologist Magali Billen of the University of California at Davis. Billen co-authored a report on the new model with former graduate student and lead author Margarete Jadamec in this week's issue of the journal Nature.
"On plate tectonics timescales that's screaming fast," said Billen.
More typical plate speeds range from one to 10 centimeters per year.
A new 3-D model of the mega-quake and tsunami-launching subduction zone in Alaska has uncovered a big surprise: The Earth's mantle there is moving a whopping 20 to 30 times faster than the crust.
So instead of being dragged along for the ride as a slab of crust is pushed under another, the solid rock mantle rock is swirling around the plunging slab like water around a paddle dipped in a stream.
What the models predict are flows up to 90 centimeters per year around the descending slab of crust, said geologist Magali Billen of the University of California at Davis. Billen co-authored a report on the new model with former graduate student and lead author Margarete Jadamec in this week's issue of the journal Nature.
"On plate tectonics timescales that's screaming fast," said Billen.
More typical plate speeds range from one to 10 centimeters per year.