MINERAL, Virginia -- Office buildings, schools and towering landmarks were being inspected Wednesday for hidden structural flaws a day after initial checks turned up little damage from a rare East Coast earthquake.
Public schools and a handful of government buildings in Washington remained closed for further assessment, and engineers were taking a closer look at cracks in the Washington Monument and broken capstones at the National Cathedral. Some residents of D.C. suburbs were staying in shelters because of structural concerns at their apartment buildings.
Further south, Tuesday's 5.8-magnitude quake also shattered windows and wrecked grocery stores near its Virginia epicenter. There were no known deaths or serious injuries.
The head of the Federal Emergency Management Agency said the quake serves as a reminder for residents to be prepared.
"We talk about hurricanes this time of year, but we forget that A: earthquakes don't have a season and B: they are not just a western hazard," FEMA administrator Craig Fugate said in an interview Wednesday on ABC's Good Morning America.
When the quake struck, many feared terrorism in New York and Washington -- places where nerves are raw as the 10th anniversary of the Sept. 11 terrorist attacks approaches. The tremblor sent many pouring from high-rises like the Empire State Building.
"I ran down all 60 flights," accounting office worker Caitlin Trupiano said. "I wasn't waiting for the elevator."
The most powerful earthquake to strike the East Coast in 67 years shook buildings and jarred as many as 12 million people. The U.S. Geological Survey said it was centered 40 miles northwest of Richmond in Mineral.
The U.S. Park Service evacuated and closed all monuments and memorials along the National Mall. The Pentagon, the White House, the Capitol and federal agencies in and around Washington were evacuated. Roads out of the city were clogged with commuters headed home.
The scope of the damage -- or lack of -- also quickly became clear on social networks. Instead of collapsed freeways, people posted images of toppled lawn chairs and yogurt cups, broken Bobbleheads, picture frames askew on walls.
A 5.8-magnitude quake releases as much energy as almost eight kilotons of TNT, about half the power of the atomic bomb dropped on Hiroshima, Japan, during World War II.
The earthquake that devastated Japan released more than 60,000 times more energy than Tuesday's, but there was real damage. At the majestic Washington National Cathedral, at least three of the four top stones on the central tower fell off, and cracks appeared in the flying buttresses at the cathedral's east end, the oldest part of the structure. The top of the Washington Monument has a crack.
Ceiling tiles fell to the floor at Reagan National Airport. The gothic-style Smithsonian Castle, built in 1857, had minor cracks and broken glass. And vigorous shaking left a crack and hole in the ceiling at historic Union Station when a chunk of plaster fell near the main entrance.
By the standards of the West Coast, where earthquakes are much more common, the Virginia quake was mild. Since 1900, there have been 40 of magnitude 5.8 or greater in California alone.
But quakes in the East tend to be felt across a much broader area, the waves traveling "pretty happily out for miles," said U.S. Geological Survey seismologist Susan Hough.
The last quake of equal power to strike the East Coast was in New York in 1944. The largest East Coast quake on record was a 7.3 that hit South Carolina in 1886.