The East Coast is not a hot earthquake zone these days. And Virginia doesn’t sit on an active earthquake fault. It was a hot earthquake zone about 200-300 million years ago. So, what caused the earthquake in Virginia today?
Well, because of its “fault scars” left over from that time probably, as pressure can build up there and cause such earthquakes to happen.
“We are just seeing pressure build up and release on those scars,” Karen Fischer, seimologist of Brown University, said. “There is a lot of debate on exactly what is going on down there and exactly how quakes this big happen in this kind of crustal zone.”
–>> You may also like: Maps of Today’s Virginia Earthquake
While earthquakes are less common on the East Coast, but with colder and firmer crust than you find on the West Coast, the shocks travel further and faster, which is why my sister and at least one East Coast writer of ours felt the earthquake very clearly all the way up in New York City.
Here’s some more information on today’s earthquake and how it compares to others in Virginia’s history from a Richmond site:
December 9, 2003: At 3:59 p.m. EST (20:59 UTC) in the foothills about 30 miles (48 kilometers) west of Richmond and was felt as far away as Norfolk; Magnitude 4.5
July 6, 2009: At 11:59:52 PM EDT about 1 km SW of Short Pump; Magnitude 2.3
So this is definitely the strongest one that many area residents have likely felt. In fact, the largest Virginia earthquake in recorded history occurred on May 31, 1897 in Giles County and is estimated to have had a magnitude of 5.8–which is what preliminary reports record this recent one as.
And more from another Virginia site:
Before today’s quake, Virginia’s largest earthquake was a 5.9 temblor that hit in Giles County in 1897 and was felt in 12 states, according to the U.S. Geological Survey.
According to the USGS website, the largest damaging earthquake in the central Virginia seismic zone occurred in 1875 and was magnitude 4.8.
Virginia has had more than 160 earthquakes in the past three decades, but only about a sixth of them were felt.
Yeah, this is unusual.