 The earthquake occurred in the Virginia Seismic Zone , located in the Piedmont region . The Virginia Piedmont area was formed originally as part of a zone of repeated continental collision that created the ancestral Appalachian Mountains , a process that started during the Ordovician period with the Taconic orogeny and finished during the Carboniferous Period with the Alleghenian orogeny . The reverse faults formed during the various orogenies were partly reactivated as normal faults in extension during the Mesozoic Era as the supercontinent Pangaea broke apart . During the Cenozoic Era , compression from the opening and spreading of the Atlantic has caused some of these structures to be reactivated in a reverse sense . 
