How the American West was made -- a new view of plate tectonics

LATimes ^ | April 3, 2013, 3:49 p.m. | Monte Morin

[BenLurkin]

It's long been held that North America's rugged and mountainous west was formed by the movement of the undersea Farallon plate, and that the process was roughly similar to the way groceries pile up at the end of a supermarket conveyor belt.

Now however, a study published Wednesday in the journal Nature argues that the process involved not just one but several plates that remain hidden deep within in the Earth's mantle.

Scientists at Ludwig Maximilians University in Munich and the British Columbia Geological Survey used earthquake shockwaves, or seismic tomography, to create a three-dimensional map of these massive plate relics, which have sunk 500 to 1,200 miles beneath the Earth's surface.

The plate slabs, according to lead author and geophysicist Karin Sigloch, resemble near-vertical walls, hundreds of feet thick.

"The largest wall runs from northwest Canada to the eastern U.S.A. and on to Central America, and has been called the Farallon slab, one of the most massive features in global tomographies," authors wrote.

"We argue that in fact most of this slab wall is not Farallon and subdivide it into the Angayucham, Mezcalera and the Southern Farallon components."

[BenLurkin]

Wish I knew what this means for potential earthquakes.

[Paladin2]

What does this mean for biotic/abiotic Hydrocarbon formation?

[BenLurkin]

This 3-D image renders the mountainous topography of the western U.S. and the ancient oceanic plate from the surface down to a depth of 1,500 kilometers (color changes in depth increments of 200 km). (Karin Sigloch / Nature / April 3, 2013)

[BenLurkin]

I think this is all deeper than we can drill.

[Paladin2]

Deeper than the CIA can drill?

MOHO?

[Sequoyah101]

I think it is pretty safe to say that this discovery will have no bearing on future earthquakes and that they will continue unabated.

[Boogieman]

“The plate slabs, according to lead author and geophysicist Karin Sigloch, resemble near-vertical walls, hundreds of feet thick.”

Near vertical plates buried deep within the continental crust... sounds kind of like Hydroplate theory.

[Standing Wolf]

...the process was roughly similar to the way groceries pile up at the end of a supermarket conveyor belt.

I suspected all along there had to be a reason all the loose junk and damaged goods ended up in San Francisco and Los Angeles.

[JoeProBono]

[catnipman]

“I think it is pretty safe to say that this discovery will have no bearing on future earthquakes and that they will continue unabated.”

I think you’re wrong. I think it’s the final piece of knowledge necessary to perfect the earthquake machine being built in Area 51.

[Sequoyah101]

You’re way ahead of me. I guess that is why I don’t have an earthquake machine yet either.

Had I only known that this piece of knowledge was all that was needed to fill in the blanks.

[SunkenCiv]

Thanks BenLurkin.

• When the Days Were Shorter [post #4 etc, 2004]

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