Posted on 04/23/2020 6:56:51 AM PDT by BenLurkin
The new research provides the first quantitative synthesis of faulting across the entire continent, as well as hundreds of measurements of compressive stress directions—the direction from which the greatest pressure occurs in the Earth's crust. The map was produced by compiling new and previously published measurements from boreholes as well as inferences about kinds or "styles" of faults based on earthquakes that have occurred in the past.
The three possible styles of faulting include extensional, or normal faulting, in which the crust extends horizontally; strike-slip faulting, in which the Earth slides past itself, like in the San Andreas fault; and reverse, or thrust, faulting in which the Earth moves over itself. Each one causes very different shaking from a hazard point of view.
In addition to presenting a continent-level view of the processes governing the North American plate, the data—which incorporates nearly 2,000 stress orientations, 300 of which are new to this study—offer regional clues about the behavior of the subsurface.
In the Eastern U.S., for example, the style of faulting revealed by the study is exactly the opposite of what would be expected as the surface slowly "rebounds" following the melting of the ice sheets that covered most of Canada and the northern U.S. some 20,000 years ago, according to Lund Snee. The discovery that the rebound stresses are much less than those already stored in the crust from plate tectonics will advance scientists' understanding of the earthquake potential in that area.
In the Western U.S., the researchers were surprised to see changes in stress types and orientations over short distances, with major rotations occurring over only tens of miles—a feature that current models of Earth dynamics do not reveal.
(Excerpt) Read more at phys.org ...
CA could drop off any day now.
I read a great book many years ago named “8.0.” It was about an 9.0 earthquake that hit the Memphis area and, for all intents and purposes, cut the country in half as it traveled up the Tennessee Valley all the way to Canada.
Based on this map that is not too far-fetched.
We see that all the time in the earl business.
I’m not buying the big red blob that runs down the entire East Coast to Florida. It is a passive margin and one would expect tension instead of compression (i.e. normal faults instead of reverse faults.) Glacial rebound all the way down to Florida? Ha.
Bump...
Why didn't they name the book "9.0"?
“Why didn’t they name the book “9.0”?”
My thought too. We need a separate thread:)
Ping
We have felt a few in Wisconsin, but I had to move to San Diego to REALLY feel one - moved the furniture away from the walls, things fell and crashed; no one hurt, no building damage though, thank goodness.
The native Californians called those, ‘Baby Quakes’ and just take them in stride. ;)
“It was about an 9.0 earthquake that hit the Memphis area and, for all intents and purposes, cut the country in half..”
When New Madrid lets go it’s gonna be epic.
L
Because they planned for an 8 and a 9 showed up?
I'd prefer if they'd just frak off.
One day someone will explain how California drops into the ocean from a massive earthquake on a transform fault. Until then-people will just remain ignorant.
The red area must mean none or near none. In my 76 years mostly spent in the red zone I have felt exactly one, a little tremor just a few years ago.
>>Why didn’t they name the book “9.0”?<<
b/c THEIR title Editor did not have as many typos as me.
It was supposed to be 8.0 hehe
Nothing on Cascadia???
The “New Madrid Seismic Zone” is just north of Memphis.
In early 1812, that area had the most powerful earthquake ever recorded east of the Rocky Mountains.
The initial quake and two aftershocks are all believed to have been at least in the 8.0 range, or higher.
The jolts were so powerful that it caused church bells to ring as far away as Washington D.C.
When New Madrid lets go it’s gonna be epic.
Little concerned about the corner between PA, Ohio and the WV panhandle. Not too far from me here in Pittsburgh.
Americans are far dumber than that. It is being reported that some people still believe that the country should have been shut down for the CORONA virus silliness.
You can fool SOME OF THE PEOPLE ALL OF THE TIME. Even President Trump fell for some of Fauxi's BS.
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