As we proceed (lurch) towards 2012, it is possible that TV networks may rerun some of these recent-past disaster movies, especially during Sweeps Months. It is cheaper than creating new ones.
[Originally posted on 5/22/06 on another of my blogs. Modified slightly for today's "consumption".]
I don't know if any of you have checked in on the NBC 3-part disaster flick "10.5 Apocalypse" (Saturday, Sunday, and this upcoming Tuesday), where the Western U.S. goes to hell in a geologic handbasket. It has just enough science to be interesting and I am waiting to see how much of the Western U.S. is laid waste.
As for likelyhood of the envisioned chain-reaction of earthquakes, volcanic eruptions, sinkholes, etc..., it answer is...
Probably Not!
[Without my Physical Geology textbook here for refresher sake, I am going from memory.]
Plate Tectonics is driven by vertical convection currents in the Asthenosphere, a semi-molten layer beneath the rocky crust (the Lithosphere). So imagine conveyor belt systems upon which the continental plates ride "piggyback". Where there are Asthenospheric "upwhellings" of molten material, if these are upwhellings are linear, they split the overlying crust and push the plates apart. This is what happens beneath the Atlantic Ocean in regards to the Mid-Atlantic Ridge and also in the Eastern Pacific Ocean with the East Pacific Rise. So there are upwhellings of intense heat in the Mid-Atlantic Ocean and the East Pacific Ocean.
In the last 30 million years or so, the North American Plate has pushed over and distorted a portion of the East Pacific Rise. A portion of the East Pacific Rise is present North of the Mendocino Fracture Zone, off the coast of N. Calif., Oregon, Washington, and British Columbia. Here the Juan de Fuca Plate is sinking beneath the North American Plate. The sinking Juan de Fuca Plate is remelting and that is what causes the occasional NW U.S. earthquakes and the Cascade Volcano eruptions (including Mt. St. Helens).
South of the Mendocino Fracture Zone along the Pacific Coast to south of the southern tip of Baja California, the coastal area is dominated by the San Andreas Fault Zone, which is where a small portion of the Pacific Crustal Plate is sliding past the North American Plate. Inland from this area, the mantle upwhelling (mantle plume) is under the continent and may be responsible for the hot spot vulcanism (San Francisco volcanic field (Flagstaff area), the Long Valley Caldera in Calif., Yellowstone in Wyoming, and perhaps the Rio Grande Rift).
The Rio Grande Rift represents a thinning of the continental crust from the El Paso area northward into central Colorado. If the continent were to be rent asunder, per the movie, this would be a natural "weak spot", as the crust appears to be thinned, based on heat-flow data, seismic surveys, and the presence of young volcanic rocks from the Potrillo Volcanic Field in Southern New Mexico, northward along the river.
The "geophysics" of the areas under the continent are different enough that stresses probably are not going to be quickly transferred from one area to another.
Another issue brought forth in the movie was the "Accelerated Plate Movement" theory as proposed by the discredited geologist father of Kim Delaney's character, Dr. Samantha Hill. If the plate motions were to reverse themselves, I would be looking at what was going on along the Mid-Atlantic Ridge. Had one of the plates started to sink in relation to the other? That would signify the reversal from an upwhelling to a subduction zone, where one plate was sinking beneath another.
Mantle upwhellings have stopped before, but we presume it takes millions of years to transpire. And I don't recall any mention of a mantle plume beneath the Western U.S., in the movie. Dr. Samantha Hill's character makes mention of "Sub-Asthenosphere" earthquakes, but to my knowledge, the "plastic" nature of the Asthenosphere makes seismic wave propogation unlikely. The most damaging earthquakes, by conventional wisdom (and supported by data) originate in the upper 100 km (60 miles) of the crust.
The deepest earthquakes are associated with the deep Pacific Ocean subduction zones and some of them originate from as much as 700 kilometers below the surface. With these deepest of earthquakes, the seismic waves are associated with the sinking oceanic plate, which though partially-melted, still retains enough rigidity to transfer stresses.
So, in summary, there are an endless number of "what ifs" and things that geologists and geophysicists dream of seeing (for the sake of learning), in this movie, and while anything is possible, it ain't likely. Remember, it is Sweeps Month.
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