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The New Yorker magazine of 20 July 2015 had an interesting article about the "Cascadia" subduction zone along the coast of N.Calif, Oregon, Washington, Br.Columbia
http://www.newyorker.com/magazine/2015/07/20/the-really-big-one
I looked up some background. Wikipedia seemed quite informative.
A seismology outreach site called IRIS also had this little animation.
http://www.iris.edu/hq/programs/education_and_outreach/animations/5
The animation shows how subduction (one plate sliding under another) can store and then release energy, and the mechanics of how abrupt changes in altitude of coastal seafloor can occur.
Rock is actually compressible and elastic.
Here is some more background by IRIS
http://www.iris.edu/hq/files/progra...ch/aotm/5/2.Subduction_Rebound_Background.pdf
I'll quote a brief excerpt of this longer article:
===quote==
...As frictional stress builds along the fault boundaries, it is accompanied by an increase in strain in the adjacent rocks. When the frictional stress exceeds a critical value, a sudden failure occurs along the fault plane that can result in a violent displacement of the Earth’s crust. When this happens, the ensuing earthquake releases elastic strain energy and seismic waves are radiated. The process of strain, stress, and failure is referred to as the elastic-rebound theory. (See page 6 for more on this topic.)
Earthquakes generated in this setting are called Great Subduction Zone earthquakes. They are the largest earthquakes in the world and can exceed magnitude 9.0. The devastating Sumatra-Andaman earthquake of December 26, 2004 (star on Figure 2) had a magnitude of 9.3.
...
...
The earthquake occurred on the interface between the India and Burma tectonic plates where the India plate is subducting beneath the overriding Burma plate. Earthquake size is proportional to fault area which was was about 1200 km long and as much as 200 km wide (See Figure 3 for a comparison of the area of the Sumatra-Andaman earthquake with the size of California.)
...The uplift caused by the elastic rebound of the overlying plate is what caused the deadly tsunami that killed over 225, 000 people. For more detail on Sumatra:
http://neic.usgs.gov/neis/eq_depot/2004/eq_041226/neic_slav_ts.html
In 1960 and 1964, destructive magnitude-9 earthquakes occurred in Chile and Alaska respectively.
...
A similar configuration of plates can be found along the Cascadia Subduction Zone (Figure 4). This is a very long sloping fault that separates the Juan de Fuca and North America plates and stretches from mid- Vancouver Island to Northern California. The contact between the two plates, the
area of the subduction zone fault, could
also produce a magnitude 9.0 earthquake, if rupture occurred over its whole area. It last ruptured on January 26, 1700 (for details see Orphan Tsunami.)
==endquote==
http://www.newyorker.com/magazine/2015/07/20/the-really-big-one
I looked up some background. Wikipedia seemed quite informative.
A seismology outreach site called IRIS also had this little animation.
http://www.iris.edu/hq/programs/education_and_outreach/animations/5
The animation shows how subduction (one plate sliding under another) can store and then release energy, and the mechanics of how abrupt changes in altitude of coastal seafloor can occur.
Rock is actually compressible and elastic.
Here is some more background by IRIS
http://www.iris.edu/hq/files/progra...ch/aotm/5/2.Subduction_Rebound_Background.pdf
I'll quote a brief excerpt of this longer article:
===quote==
...As frictional stress builds along the fault boundaries, it is accompanied by an increase in strain in the adjacent rocks. When the frictional stress exceeds a critical value, a sudden failure occurs along the fault plane that can result in a violent displacement of the Earth’s crust. When this happens, the ensuing earthquake releases elastic strain energy and seismic waves are radiated. The process of strain, stress, and failure is referred to as the elastic-rebound theory. (See page 6 for more on this topic.)
Earthquakes generated in this setting are called Great Subduction Zone earthquakes. They are the largest earthquakes in the world and can exceed magnitude 9.0. The devastating Sumatra-Andaman earthquake of December 26, 2004 (star on Figure 2) had a magnitude of 9.3.
...
...
The earthquake occurred on the interface between the India and Burma tectonic plates where the India plate is subducting beneath the overriding Burma plate. Earthquake size is proportional to fault area which was was about 1200 km long and as much as 200 km wide (See Figure 3 for a comparison of the area of the Sumatra-Andaman earthquake with the size of California.)
...The uplift caused by the elastic rebound of the overlying plate is what caused the deadly tsunami that killed over 225, 000 people. For more detail on Sumatra:
http://neic.usgs.gov/neis/eq_depot/2004/eq_041226/neic_slav_ts.html
In 1960 and 1964, destructive magnitude-9 earthquakes occurred in Chile and Alaska respectively.
...
A similar configuration of plates can be found along the Cascadia Subduction Zone (Figure 4). This is a very long sloping fault that separates the Juan de Fuca and North America plates and stretches from mid- Vancouver Island to Northern California. The contact between the two plates, the
area of the subduction zone fault, could
also produce a magnitude 9.0 earthquake, if rupture occurred over its whole area. It last ruptured on January 26, 1700 (for details see Orphan Tsunami.)
==endquote==
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