When the ground started shaking on August 23, many people in and around the District assumed that their biggest fears had been realized — a terrorist had struck again. Beyond surprising many, the 5.9 magnitude earthquake also exposed the longstanding post-9/11 nervousness that comes with living in one of the places that the terrorist struck on that day. Call it the 9/11 psyche — it’s not if we’re going to be attacked again, but rather when.

Over the decade since the 9/11 attacks, the D.C. area has been victim of plenty of panics, threats and warnings. We’ve also had to deal with increased security measures, everything from bag searches on Metro to more aggressive use of closed-circuit cameras on city streets and new online tip-sharing initiatives. But in a twist summarized yesterday by N.R. Kleinfield in The New York Times, “[The] actuality has been that terrorist acts on American soil in the succeeding years have been, as always, largely homegrown.”

Below we look back on 10 years of threats to our fair city, whether actual terrorist attempts or simply acts that terrorized an area already on edge. This list is hardly exhaustive, but a sample of some of the most notable threats we’ve faced.

Anthrax Attacks Hit Home: Shortly after the September 11 attacks, a number of envelopes containing what was found to be anthrax spores were mailed to two senators and several media outlets, killing five and injuring 17. Two of those killed worked in the District’s Brentwood mail-sorting facility. While there was never a conviction in the case, government lawyers announced in 2008 that Bruce Edwards Ivins, a government scientist, was their sole suspect. Only one problem, though — he died of an overdose a year earlier. The case was closed in 2010.

D.C. Sniper Truly Terrorizes D.C. Area: In what may be the biggest local post-9/11 irony, it was two men with a sniper rifle that terrorized the Washington area in 2002, not a group of committed jihadi terrorists. In October of that year, John Allen Muhammad and Lee Boyd Malvo killed 10 and critically injured three others by shooting them from a makeshift compartment in the back of a blue Chevy Caprice. What made Muhammad and Boyd’s reign of fear so effective was the sheer randomness of it — their victims fell everywhere from a Home Depot parking lot to a Mobil gas station. Initial reports that the D.C. Sniper was driving a white van provoked countless “sightings” on area roads, and nervous drivers were told not to stand by their cars as they pumped gas. Muhammad and Boyd were eventually caught at an I-70 rest stop; Muhammad was executed by Virginia in 2009.

Tractor Man Invades Constitution Gardens: In March 2003, the District awoke to a man who had driven a tractor into a pond in Constitution Gardens. What would have otherwise have seemed like a good joke turned into a two-day-long traffic-snarling ordeal, as police negotiated with disgruntled North Carolina tobacco farmer Dwight Ware Watson, who claimed to have explosives. He didn’t, and ended up surrendering peacefully and serving 16 months in prison. Whatever his grief with the federal government became less an important question than finding out how exactly a man on a tractor drove into the heart of the city without anyone noticing, caring or calling the cops to tell them.

Kentucky Governor Provokes Panic: In June 2004, an unidentified aircraft entered the District’s airspace, provoking a panicked evacuation of federal buildings and the U.S. Capitol and scrambling nearby fighter jets. It ended up being not much of a threat, though — it was just Kentucky Gov. Ernie Fletcher (R), flying into town for Ronald Reagan’s funeral. (This happens often, it seems.)

Explosive-Laden Van Shuts Down White House: Just as the District prepared for President George W. Bush second inauguration in 2005, another disgruntled American decided to park a vehicle in an obvious location and threaten to blow himself up. Michigan resident Lowell Timmers stopped his van just in front of the White House security gates on Fifteenth Street, provoking a four-hour standoff that ended peacefully. A subsequent police investigation found that while he had the components to make a bomb, they weren’t hooked up.

White Supremacist Opens Fire at Holocaust Museum: In June 2009, white supremacist James Wenneker von Brunn opened fire in the U.S. Holocaust Museum, killing 39-year-old guard Stephen Tyrone Johns.

Metro Bomber, Or Not?: Late last year the FBI announced that it had arrested Virginia resident Farooque Ahmed for plotting to blow up a number of Metro trains and stations. But much like a similar plot discovered in Oregon, Ahmed was found to have been willing — but not exactly a terrorist mastermind. Undercover FBI agents prodded him along throughout the investigation, leaving some to ask whether or not Ahmed would have had the wherewithal to do any damage if left to his own devices. In April 2011, he was sentenced to 23 years in jail.

Anthrax Attacks, 2.0: Last May, some 30 D.C. public schools shut down after envelopes filled with white powder were received. While the powder proved to be harmless, the incident showed that the memory of the 2001 anthrax attacks were fresh in the minds of many.

Plenty of Crazies by the Capitol: In 2006, the Rayburn Office Building went into lockdown after gunshots were reported. (It ended up being construction workers.) In 2008, police captured a man near the U.S. Capitol armed with a shotgun, a Samurai sword and a bow and arrow. In 2010, U.S. Capitol police shot a man with a gun as he neared the complex. And just last month, police arrested a Florida man who had packed his jeep with fireworks — and the ability to launch them. Needless to say, the U.S. Capitol attracts its fair share of nutcases, some with violent intentions, other without. Police often err on the side of caution, and given the deadly 1998 shooting that killed to Capitol Police officers, it’s understandable why.

Leftover Chinese or a Deadly Explosive?: If there’s one thing that’s as unavoidable as death and taxes, it’s being forced to wait until police can finish investigating yet another suspicious package somewhere in the District. If by chance you leave an empty lunchbox in your favorite park, chances are that the authorities will shut down a three-block radius and break out the bomb-detecting equipment. This isn’t to say that vigilance isn’t required in these troubled times, but that the vigilance can be provoked by even the most insignificant personal oversights.

Mother Nature Proves a Wily Terrorist: No one event has tested the region’s capacity to deal with terrorism as much as the weather has. Whether a snowpocalypse, ice storm, hurricane, or earthquake, each time Mother Nature has come after the District we’ve stormed local supermarkets and clogged area roads. Worse yet, after a decade of planning, one vital question remains unanswered — who actually has the authority to evacuate the city?

This certainly isn’t all of the threats we’ve faced — if we left any out, leave ’em in the comments — but something of a representative sample. This isn’t to say that the District doesn’t face a real danger from terrorists and extremists, but that many of the threats we’ve weathered have been of the homegrown variety. Additionally, there’s a Catch-22 in the whole security business — we’ll never really know how close someone may have gotten to getting us, leaving us with little option other than to assume that everything could be the worst of what we’ve feared since September 11, 2001.