Fault Crossroads May Have Been Origin Point for 2011 Virginia Earthquake

Caption: In map view, magnetic information were filtered (colors) to highlight geologic features close the earthquake depth. One contrast (blue dotted line) is aligned alongside aftershocks (black dots). The other crosses at an angle. They advise that the earthquake (yellow star) occurred close a “crossroads,” or a complex intersection of different types of rock.

The 2011 due east coast earthquake felt yesteryear people from Georgia to Canada probable originated from a error “junction” only exterior of Mineral, Virginia, according to novel U.S. Geological Survey enquiry published inwards the Geological Society of America’s Special Papers.
Following the August 23, 2011 event, USGS scientists conducted low-altitude geophysical (gravity as well as magnetic) flying surveys inwards 2012 over the epicenter, located nearly 8 miles from the quake’s namesake. Maps of the earth’s magnetic plain as well as gravitational delineate demo subtle variations that reverberate the physical properties of deeply buried rocks. More enquiry may disclose whether geologic crossroads such every bit this are conducive to futurity earthquakes inwards the eastern United States.
“These surveys unveiled non entirely ane fault, which is roughly aligned alongside a error defined yesteryear the earthquake’s aftershocks, but a bit error or contact betwixt different stone types that comes inwards at an angle to the offset one,” said USGS scientist as well as atomic number 82 investigator, Anji Shah. “This visual suggests that the earthquake occurred close a ‘crossroads,’ or junction, betwixt the error that caused the earthquake as well as around other error or geologic contact.”
Deep imaging tools were specifically chosen because the earthquake occurred nearly v miles beneath the earth. Looking at faults inwards this agency tin assist scientists ameliorate empathize earthquake hazards inwards the eastern United States.
The USGS as well as partner scientists are also interested inwards why seismic events occur inwards sure enough parts of the cardinal as well as eastern United States, similar the Central Virginia seismic zone, since at that topographic point are no plate boundaries there, different the San Andreas Fault inwards California, or the Aleutian Trench inwards Alaska.
USGS scientists nonetheless bring remaining questions:  Could this tumble out elsewhere? How mutual are such crossroads?  Shah as well as other scientists are also trying to empathize whether as well as why a junction similar this powerfulness live an root betoken for earthquakes.
“Part of it powerfulness live the complex stress patch that arises inwards such an area. Imagine yous bring a plastic H2O bottle inwards your hand, as well as it has a cutting (fault) inwards it the long way. When yous squelch the bottle, it pops (ruptures) where the cutting is.  The long cutting is comparable to an ancient error – it’s an expanse of weakness where displace (faulting as well as earthquakes) is to a greater extent than probable to happen. Multiple intersecting cuts inwards that bottle hit zones of weakness where error skid is to a greater extent than probable to happen, peculiarly where ii cuts intersect,” said Shah.
The province of affairs close the error on which the magnitude 5.8 Mineral earthquake occurred is to a greater extent than complex than that. For example, the error may split different types of rocks alongside varying densities as well as strengths, every bit suggested yesteryear the gravity data. This contributes to a complex stress plain that could also live to a greater extent than conducive to slip.
source: U.S. Department of the Interior, U.S. Geological Survey

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