Pennsylvania Avenue NW, looking east about 15 minutes after Tuesday afternoon’s earthquake. (Mike DeBonis/The Washington Post)

Here was my thought process at 1:51 p.m., experienced at a downtown tavern with half a club sandwich in my mouth: Whoa, is this an earthquake? No, we’re in D.C., this can’t be an earthquake. Oh, god, it’s a bomb. I’m two blocks from the White House. Definitely a bomb. Wait, no, the building still has windows — not a bomb. Is there a really big truck driving by? No truck is that big. Wait, it’s been shaking for a good five seconds now. This is an earthquake. Whoa.

Some other reactions gathered by myself and Post colleagues:

— “The house began to rumble, like when you hear a large truck rolling by.”

— “At first I thought it was people running through the building. Like a bunch of adults running down the hall.”

— “We thought someone was banging on the cubicle beside us.”

— “I thought someone was rolling something heavy in the building.”

— Person working out thought she “threw the barbell down too hard.”

But over and over again, my colleagues and I heard people say they thought it was bomb or some other sort of explosion. Behold the post-9/11 collective psyche.

So what were you thinking? Tweet to the #quakereaction hashtag and I’ll update here.

MORE ON THE EARTHQUAKE:

What a seismologist had to say

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Capital Weather Gang: Updates from the ground

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Strongest quake in Va. since 1897

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Share your photos of the quake

Ezra Klein: The best earthquake tweets

Time for a family disaster plan