Farallon Plate
Thursday, 22. March 2007, 09:08:22
"Descent of the ancient Farallon slab drives localized mantle flow below the New Madrid seismic zone" is the title of an article in the Geophysical Research Letters, VOL. 34, L04308, doi:10.1029/2006GL027895, 2007
Scientists studying extraordinary earthquakes along the New Madrid seismic zone nearly 100 years ago find that remnants of the ancient Farallon plate, a slab of crust swallowed beneath the western North American continental margin several million years ago, continue to descend into the deep mantle under central North America. The descent induces mantle flow towards the Earth’s deep interior directly below the New Madrid seismic zone, which may lead to earthquakes in the overlying crust.
The Farallon plate was an enormous oceanic plate located west of the Americas during the Cenozoic and Mesozoic eras. The Farallon Plate plate has now been almost completely subducted beneath the American plates. The Farallon Plate began subducting under the west coast of the North American Plate — then located in modern Utah — as Pangaea broke apart during the Jurassic period. Over time the central part of the Farallon Plate completely subducted under the southwestern part of the North American Plate. Around 23 million years ago, the remnant of the Farallon Plate split into the Juan de Fuca Plate subducting under the northern part of the North American Plate, the Cocos Plate subducting under Central America and the Nazca Plate subducting under the South American Plate.
It is thought that much of the plate initially went under North America (particularly the western United States and southwest Canada) at a very shallow angle, creating much of the mountainous terrain in the area (particularly the American Rocky Mountains). A large fragment of the subducted plate is believed to presently be in the mantle under eastern North America.
The image (to the left) is from the USGS page: http://pubs.usgs.gov/gip/dynamic/Farallon.html
New Madrid Seismic Zone
In the winter of 1811-1812, the central Mississippi Valley was struck by three of the most powerful earthquakes in U.S. history. Even today, this region has more earthquakes than any other part of the United States east of the Rocky Mountains. Seismic map of New Madrid Seismic Zone. Credit USGS.
Scientists studying extraordinary earthquakes along the New Madrid seismic zone nearly 100 years ago find that remnants of the ancient Farallon plate, a slab of crust swallowed beneath the western North American continental margin several million years ago, continue to descend into the deep mantle under central North America. The descent induces mantle flow towards the Earth’s deep interior directly below the New Madrid seismic zone, which may lead to earthquakes in the overlying crust.
The Farallon plate was an enormous oceanic plate located west of the Americas during the Cenozoic and Mesozoic eras. The Farallon Plate plate has now been almost completely subducted beneath the American plates. The Farallon Plate began subducting under the west coast of the North American Plate — then located in modern Utah — as Pangaea broke apart during the Jurassic period. Over time the central part of the Farallon Plate completely subducted under the southwestern part of the North American Plate. Around 23 million years ago, the remnant of the Farallon Plate split into the Juan de Fuca Plate subducting under the northern part of the North American Plate, the Cocos Plate subducting under Central America and the Nazca Plate subducting under the South American Plate.
It is thought that much of the plate initially went under North America (particularly the western United States and southwest Canada) at a very shallow angle, creating much of the mountainous terrain in the area (particularly the American Rocky Mountains). A large fragment of the subducted plate is believed to presently be in the mantle under eastern North America.
The image (to the left) is from the USGS page: http://pubs.usgs.gov/gip/dynamic/Farallon.html
New Madrid Seismic Zone
In the winter of 1811-1812, the central Mississippi Valley was struck by three of the most powerful earthquakes in U.S. history. Even today, this region has more earthquakes than any other part of the United States east of the Rocky Mountains. Seismic map of New Madrid Seismic Zone. Credit USGS.
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