Posted on 08/30/2015 8:38:47 PM PDT by JimSEA
It’s not a huge mystery why Los Angeles experiences earthquakes. The city sits near a boundary between two tectonic plates — they shift, we shake. But what about places that aren’t along tectonic plate boundaries?
For example, seismicity on the North American plate occurs as far afield as southern Missouri, where earthquakes between 1811 and 1812 estimated at around magnitude 7 caused the Mississippi River to flow backward for hours.
Until now, the cause of that seismicity has remained unclear.
While earthquakes along tectonic plate boundaries are caused by motion between the plates, earthquakes away from fault lines are primarily driven by motion beneath the plates, according to a new study published by USC scientist Thorsten Becker in Nature on Aug. 27.
Just beneath the Earth’s crust is a layer of hot, semi-liquid rock that is continually flowing — heating up and rising, then cooling and sinking. That convective process, interacting with the ever-changing motion of the plates at the surface, is driving intraplate seismicity and determining in large part where those earthquakes occur. To a lesser extent, the structure of the crust above also influences the location, according to their models.
“This will not be the last word on the origin of strange earthquakes. However, our work shows how imaging advances in seismology can be combined with mantle flow modeling to probe the links between seismicity and mantle convection,” said Becker, lead author of the study and professor of Earth sciences at the USC Dornsife College of Letters, Arts and Sciences.
Becker and his team used an updated mantle flow model to study the motion beneath the mountain belt that cuts north to south through the interior of the Western United States.
The area is seismically active — the reason Yellowstone has geysers is that it sits atop a volcanic hotspot. Previously, scientists had suggested that the varying density of the plates was the main cause. (Imagine a mountain’s own weight causing it to want to flow apart and thin out.)
Instead, the team found that the small-scale convective currents beneath the plate correlated with seismic events above in a predictable way. They also tried using the varying plate density or “gravitational potential energy variations” to predict seismic events and found a much poorer correlation.
“This study shows a direct link between deep convection and shallow earthquakes that we didn’t anticipate, and it charts a course for improved seismic hazard mapping in plate interiors,” said Tony Lowry, co-author of the paper and associate professor of geophysics and geodynamics at Utah State University.
Becker and Lowry collaborated with researchers from University Roma Tre in Italy, the University of New Mexico, Scripps Institution of Oceanography and the Massachusetts Institute of Technology.
The full study can be found online at http://dx.doi.org/10.1038/nature14867. This research was supported by the National Science Foundation, grants EAR-0350028, EAR-0732947, EAR-1215720, EAR-1215757, EAR-0955909, and EAR-1358622; and by the Southern California Earthquake Center.
OH REEEALY, and here I thought it was caused by inner planetary GOREBAL WARMING GAS.
gee- you mean fracking isn’t the cause?
Mother Earth is just having a high flow day.
And she gets some of those monster zits. Don’t want to be around when they pop.
What! I thought from the earth was hollow and aliens lived there.
We seem constantly to ignore how puny our efforts are in comparison with the actions of nature, how limited our ability to predict what those actions shall be,
On a good day, we humans are along for the ride. On a bad day, we get bucked off or trampled.
I’ve long suggested the Mid-American rift is the cause of the swarm in KS and OK.
The earth is seething with magma, coming out of its wherever.
“Intraplate earthquakes and seismic activity.”
This press release full of misinformation is a prime example of the incompetence of today’s California universities. The New Madrid Fault system and its associated earthquakes IS NOT an example of “intraplate earthquakes” as claimed. They ARE an example of “interplate earthquakes,” because the New Madrid fault is the remnant of an ancient continental rift in the North American Plate which continental drift opened and then closed together again while leaving the divided plate margins of the old rift free to continue colliding and generating seismic activity not unlike other plate boundaries. In other words, the inter-plate activity is occurring between two margins of the same continental plate, which were destined to divide the North American Plate into two separate continental plates, until the rifting was halted by a change in continental drift and the rift became incompletely closed.
The example of the seismic activity at Yellowstone National Park is a different type of activity unrelated to the rifting of the New Madrid Fault or today’s comparable rifting of a smaller East Africa plate from the main African continental plate.
It should also be noted that the major rivers of the North American Plate are located along major fractures in the North American Plate. Examples are the Mississippi River, Ohio River, Wabash River, Missouri River, Red River, and others. Prior to a plate separating from what was to become today’s Europe, spinning around, and then slamming into the North American plate to become its eastern seacoast, the ancient Ohio River ran downstream from the Himalayan sized mountains of present day Arkansas, Missouri, Illinois, Indiana, and Kentucky eastwards to empty into the sea. It was redirected to the Gulf of Mexico much later in time after the continental plate collision along the eastern coasts created the Appalachian mountain ranges.
“I’ve long suggested the Mid-American rift is the cause of the swarm in KS and OK.”
The New Madrid Fault System
Earthquake activity in the New Madrid region is concentrated in an area of weak ancient crust called the Reelfoot Rift. About one billion years ago the
continent began to rift apart in this region, but the rifting never completed. What remains is a weak zone in the continent which has been reactivated by present-day stresses in Earth, resulting in seismic activity.
http://www.eas.slu.edu/eqc/eqc_publ/Flyers/PDFs/NMstructure.pdf
Mechanism Behind “Strange” Earthquakes
I figured it was a strange earthquake machine, but your post works as well.
Liquid hot magma if you don’t send me ONE MILLION DOLLARS!
Yeah, well, you know, that's just, like, your opinion, man...
It’s obvious the number of people on the edges are causing it to shift and could possibly lead to the entire country sinking.
I know what you’re thinking, but it is as plausible as global warming.
Bookmarking...
It is! The Illuminatti obviously planted this story to throw those of us in the know off the scent! Not gonna work! No sirree...
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