MINERAL, Va. — Tens of millions of people from Georgia to Canada were jolted Tuesday by the strongest earthquake to strike the East Coast since World War II. Three weeks before the 10th anniversary of Sept. 11, office workers poured out of New York skyscrapers and the Pentagon, relieved it was nothing more sinister than an act of nature.

There were no known deaths or serious injuries, but cracks appeared in the National Cathedral and three capstones broke off its tower. Windows shattered and grocery stores were wrecked in Virginia, where the quake was centered. The White House and Capitol were partly evacuated.

The U.S. Geological Survey said the quake registered magnitude 5.8. By West Coast standards, that is mild. But the East Coast is not accustomed to earthquakes at all, and this one unsettled some of the nation’s biggest population centers.

In New York and Washington, people said their thoughts were of an explosion or terrorist attack. In some cases, workers in Washington mentioned the tremors in calls to colleagues in New York, and seconds later, the shaking reached there, too.

“We thought it was a bomb at first because everyone has 9/11 on the brain and that it’s so close to September and the 10th anniversary,” said Cathy McDonald, who works in an IRS office in downtown Washington.

Hundreds of people spilled out of the federal courthouse blocks from ground zero after the quake struck just before 2 p.m. Workers in the Empire State Building rushed into the streets, some having descended dozens of flights of stairs.

“I thought we’d been hit by an airplane,” said one worker, Marty Wiesner.

Adrian Ollivierre, an accountant who was in his office on the 60th floor when the shaking began, said: “I thought I was having maybe a heart attack, and I saw everybody running. I think what it is, is the paranoia that happens from 9/11, and that’s why I’m still out here – because, I’m sorry, I’m not playing with my life.”

The quake was felt as far north as Toronto, as far west as Indiana and Kentucky and as far south as Atlanta and Savannah, Ga. It was also felt on Martha’s Vineyard, where President Obama, who is vacationing there, was getting ready to tee off in a round of golf.

The White House said there were no reports of major damage to the nation’s infrastructure, including airports and nuclear facilities. Two nuclear reactors at the North Anna Power Station in Virginia were automatically taken offline by safety systems, said Roger Hannah, a spokesman for the U.S. Nuclear Regulatory Commission. The plant is in the same county as the quake’s epicenter, about 80 miles southwest of Washington and 40 miles northwest of Richmond, Va.

The Park Service closed all monuments and memorials on the National Mall, and ceiling tiles fell at Reagan National Airport outside Washington. Many nonessential workers in Washington were sent home for the day. The Capitol was reopened by late afternoon for people to retrieve their things.

Ken Lundberg, communications director for Sen. Olympia Snowe, R-Maine, described a jolting experience.

“It was like someone put our building on springs and shoved us sideways,” Lundberg said. “It was quite a jolt.”

Jessica James, a staffer for Sen. Susan Collins, R-Maine, said she was at her desk when she felt the tremor begin.

“I had never felt anything like it. Ceiling tiles fell,” James, who is from Rumford, said via email. “There was a calm, organized evacuation of the building. We are trained and know what to do in case of an emergency like this. Sen. Collins contacted us immediately to make sure we were all safe, and fortunately we are. But it was definitely frightening.”

Congress is on its August recess, so Maine lawmakers were back home in the state. A number of staffers were working in state and district offices as well.

That was the case with the office of 1st District Democratic Rep. Chellie Pingree. Willy Ritch, spokesman for Pingree, said her Capitol office is closed this week, with staffers who are not on vacation working in Pingree’s district office.

Lindsay Chard, a Deering High School graduate who works for the National Law Enforcement Officers Memorial Fund in Washington, said her building was evacuated for about an hour.

“It was freaky. I’ve never felt that before,” the Portland native said of the building shaking. “To be honest, my first thought was terrorist attack.”

At the Pentagon, a low rumbling built until the building itself was shaking, and people ran into the corridors of the complex. The shaking continued, to shouts of “Evacuate! Evacuate!” The main damage to the building, the largest single workspace for the federal government, came from a broken water pipe.

The National Cathedral said it had sustained “significant damage,” with three capstones, each shaped like a fleur-de-lis, breaking off the main tower. Cracks appeared in the flying buttresses around the apse at the cathedral’s east end, the oldest part of the building.

“Please pray for the cathedral as there has been some damage,” the cathedral said on its official Twitter feed.

Around Mineral, Va., a small town close to the epicenter, people milled around outside, still rattled and leery of re-entering buildings. There were stores with shelf contents strewn on the floor. Several display windows at businesses were broken and lay in jagged shards.

Carmen Bonano, who has a 1-year-old granddaughter, sat on the porch of her family’s white-frame house, its twin brick chimneys destroyed.

“The fridge came down off the wall and things started falling. I just pushed the refrigerator out of the way, grabbed the baby and ran,” she said.

By the standards of the West Coast, where earthquakes are much more common, the Virginia quake was not strong. Since 1900, there have been 50 quakes of magnitude 5.8 or greater in California alone. Quakes in the East tend to be felt across a much broader area.

The Geological Survey put the quake in its yellow alert category, meaning there was potential for local damage but relatively little economic damage.

The agency said the quake was 3.7 miles beneath the surface, but scientists said they may never be able to map the exact fault. Aftershocks may help outline it, said Rowena Lohman, a Cornell University seismologist. There have been a few aftershocks. Two were magnitudes 2.2 and 2.8, but a later one measured 4.8.

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. In 1897, a magnitude-5.9 quake was recorded at Giles County, Va., the largest on record in that state.

A 5.8-magnitude quake releases as much energy as almost 8 kilotons of TNT, about half the power of the atomic bomb dropped on Hiroshima, Japan. The earthquake that devastated Japan earlier this year released more than 60,000 times as much energy as Tuesday’s quake.

The Virginia quake came a day after an earthquake toppled groceries off shelves and caused minor damage to homes in southern Colorado and northern New Mexico. No injuries were reported as aftershocks continued Tuesday.

For the most part, the East Coast quake was a curiosity, at least after the initial fear faded. It disrupted what was, for millions of people, an ordinary workday.

Amtrak said its trains between Baltimore and Washington were at reduced speeds and crews were inspecting stations and railroad infrastructure before returning to normal.

John Gurlach, air traffic controller at the Morgantown Municipal Airport in West Virginia, was in a 40-foot-tall tower when the earth trembled.

“There were two of us looking at each other saying, ‘What’s that?’” he said, even as a commuter plane was landing. “It was noticeably shaking. It felt like a B-52 unloading.”

Immediately, the phone rang from the nearest airport in Clarksburg, and a computer began spitting out green strips of paper – alerts from other airports in New York and Washington issuing ground stops “due to earthquake.”

Bethany Lowe, originally of Saco, who now works at a private school in Middleburgh, Va., about 100 miles north of Richmond, was talking to co-workers in her office when she felt the building shake.

“We didn’t know if a big truck was going by, then things started shaking side to side more aggressively and I said, ‘We are having an earthquake,’” she said.

“It wasn’t like there was anything falling that made it hazardous to leave, so everybody hustled outside where it was pretty open. … Everybody was just kind of in awe that we just had an earthquake.”

The earthquake caused a stir online, where people posted to Facebook and Twitter within seconds and described what they had felt. The keywords in posts included “DCquake,” “VAquake” and “Columbusquake,” an indication of how broadly the quake was experienced.

On the West Coast, where the last major quake in a metro area was a magnitude-6.7 event that ravaged greater Los Angeles in 1994, what happened back East was cause for outright mockery.

“Californians yawn, shrug and go back to their iced lattes,” Marcus Beer, who reviews video games for a local news broadcaster, said in a Twitter post.


– MaineToday Media Washington Bureau Chief Jonathan Riskind contributed to this report.