well-nigh five year ago , a 5.8 - magnitude earthquakestruckMineral , Virginia , jolting Washington D.C. and much of the eastern third of the United States . scientist were baffled by the seism , which was the strong in the region in 67 eld and one of only a fistful of notable earthquake inside the North American Platesince 1737 .
Most earthquakes take home at the boundaries of architectonic plates , not the middle ; so - calledintraplate earthquakeslike the 2011 one are rarer , and their causes are not well understand . Now , the American Geophysical Union ( AGU)reportsthat seismologists believe they ’ve discovered the ground for the comparatively late tremors in the southeastern U.S.
According to a study published in the beginning this week inJournal of Geophysical Research – Solid Earth , the quakes that have take place in the region over the yr were likely the solution of chunks of the drape under the region fall into the Earth , which leave behind the remaining plate more vulnerable to the slipping that causes earthquake . The expanse the researchers study , in the southeast U.S. , are rough 1056 miles from the nearest bound of the North American Plate .
Initially , the scientists ask to find grounds of ancient mistake lines . Instead , they discovered a disparity in the thickness of the plates in the southeastern U.S. ; some division of the plate were made of thick , quondam rock ‘n’ roll that stretched down into the Earth , while others were made of lighter , jr. rock candy . From the AGU :
The dilutant and younger the plate , the more potential it is to slip along ancient fault lines , trigger an earthquake , they say .
“ This was an interesting finding because everybody call up that this is a static region , and we would look even plateful heaviness , ” Berk Biryol , a seismologist at the University of North Carolina Chapel Hill and the lead generator of the novel subject field , toldthe AGU .
Biryol lend that mantle pieces are likely still breaking off from the denture , a process which begin an estimated 65 million years ago . The on - go geological phenomenon mean that temblor and other seismal bodily function will probably continue in the part .
“ Our musical theme supports the view that this seismicity will keep due to demented stresses in the plate , ” Biryol say . “ The [ seismal ] zones that are combat-ready will go on to be alive for some clock time . ”
