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The most powerful East Coast earthquake in 100 years also sent tremors four times further and over an area 20 times wider than similar quakes in other parts of the public , new inquiry has found .
The Aug. 23 , 2011,Virginia earthquaketriggered small rockfalls 150 miles ( 245 klick ) away from the epicentre , by far the greatest landslide distance recorded from any similar - order of magnitude quake worldwide , grant to the inquiry , which was presented on Nov. 6 at the annual coming together of the Geological Society of America ( GSA ) in Charlotte , N.C. For compare , a similar consequence center on an active fault at a Los Angeles beach would have only loosened rock-and-roll 36 naut mi ( 60 kilometer ) off at the Hollywood mansion — notcaused landslidesat the border with Mexico .
Did you feel it? A map shows the wide reach of the 2011 Virginia earthquake.
" In the Eastern U.S. , you might have smaller earthquakes , but they will be mat over a much larger area , " said study carbon monoxide - author Randall Jibson , a geologist with the U.S. Geological Survey ( USGS ) in Denver . " They ’re feel about 20 times over the orbit that the same earthquake would be mat in the westerly U.S. " [ Infographic : Earthquake Shakes Northeastern US ]
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Jibson ’s analytic thinking suggests major cities along the East Coast face a enceinte seismic hazard than previously thought .
Did you feel it? A map shows the wide reach of the 2011 Virginia earthquake.
" I think what we ’re hop is that it ’s a come alive - up call , " Jibson state OurAmazingPlanet . " There are few earthquake in the East than in the West , and they lean be a little smaller , but in a high-risk style , you get more eruption for the buck . "
The culprit behind the all-encompassing shaking looks like geologic structures within the Appalachian Mountains , whose gentle curve reflect the twisted corpse of ancient continental collisions . The Appalachian bedrock seems to transfer seismal vigor parallel to the mountain ’s due north - south orientation , according to several studies present during the same GSA meeting session , while fault , faults and other structures impede change of location perpendicular to the range .
" We ’ve amaze three or four lines of grounds that seem to show seismic wave travel much more expeditiously along than across it , " Jibson say . " It ’s just easy to go along the complex body part than go across all these discontinuity . "
Map showing landslide limits from the Aug. 23, 2011, Virginia earthquake. The star indicates the epicenter; large crosses are landslide limits. The bold line shows a best-fit ellipse centered at the epicenter and passing through the observed limits (dashed where inferred beyond limits).
The same pattern appears on the USGS " Did You Feel It " plots from the Virginia temblor , which map online story from residents in the earthquake zona . The quake was feel byas many as 100 million people , from Florida to southeastern Canada , and caused $ 200 million in damage , the USGS say in a recent statement .
Eyes on the ground
In an age of artificial satellite single-valued function andairborne radar , the pairtracked down each bantam rock ‘n’ roll lot in a decidedly more low - technical school way : drive around in a rental railcar to find them . In the week espouse the quake , they drove outwards from the epicentre along transects , looking for evidence of fresh landslides on steep side . They would stop frequently along route cuts to overturn rocks , looking for fresh grass underneath — a polarity that the rock could have fallen during the earthquake .
" It was old - fashioned detective work , " Jibson say . The slides caused no legal injury or injuries .
Landslides covered an arena of about 12,900 hearty miles ( 33,400 square kilometer ) — about 20 times larger than expected . Previous study predicted an sphere of about 580 square mile ( 1,500 satisfying km ) from a 5.8 - magnitude earthquake .
" This particular observation is passably significant in how we betoken and therefore prepare for future earthquakes , " Jibson said . " We have equations that predict how strongly the ground will shake for a cave in quake , and those assume the footing will shake evenly out in a given instruction . The people who put those equality together might call for to adjust the equation , " he said .
The detailed report of the findings will appear in the December issue of the Bulletin of the Seismological Society of America .
