A 5.8 magnitude earthquake based in Virginia just scared the heck out of millions of people. Tremors shook from Washington, D.C. to New York City and many buildings were evacuated. Standing in the streets, waiting to find out details on what was going on, most people probably called home to check in. Then they read the news on their mobile devices. And then they probably hit app stores for earthquake apps.

“Sales of the app move with seismicity,” said app developer Danny Goodman, who created the iFeltThat app for monitoring earthquakes (more on the app below). “This is more so the case  for U.S.-based events, but there’s no question about it. All of the sudden you have a whole segment of the country vitally interested and willing to buy earthquake apps.”

Today a massive group of individuals who have never had to worry about earthquakes got a taste of the danger, and now they want to be informed. Having an app to consult during a disaster can make you feel a bit more empowered when everything else is out of control. It just so happens I’m an earthquake geek, and here are my three favorite apps for that.

The best iPhone earthquake app is iFeltThat ($0.99; left). It was created by Goodman, and is also available on the iPad. First, it tells you if that really was just an earthquake you felt. Living in San Francisco, I have imaginary tremor moments, so I use this feature often. The app displays information on earthquakes from around the world based on multiple official sources for data. You can set up custom regions to monitor (I picked Northern California and San Francisco). One of the coolest features is iFeltThat’s use of your address book — you can find out if an earthquake happened near one of your contacts.

“I started working on the concept of this app in 1989,” says Goodman, who was sitting in San Francisco’s Candlestick Park during the Loma Prieta earthquake. “The power went out and the stadium had no backup. We were cut off from the world, and this was before cellphones. As a nerd, I had a scanner radio to listen to stadium activity. The one thing I wanted to know was how big and how far away the quake was, and I heard it from the Coast Guard, who was reporting on the Bay Bridge damage. That made me appreciate the scope and size of the event. That’s what lead to iFeltThat.”

Earthquake Alarm ($0.99) is an iPhone app that uses the accelerometer of the iPhone to detect subtle changes in angle. When things start to get bumpy, the app sounds an alarm. There’s normal mode and high sensitivity mode. An algorithm detects abnormal vibrations. If movements continue for more than 10 seconds, the alarm goes off. My massive Labrador can walk by my phone when it’s in normal mode and his vibrations don’t set it off. I haven’t had the chance to test the alarm function during a real earthquake, but I have had it on since this morning’s earthquake. You know, just in case.

Another creative earthquake app is Earthquake! (free) by Reto Meier (right), which is available for Android. What’s so darn smart about this app is its use of the phone’s vibration alert. When an earthquake happens, the amount of the phone’s vibration indicates the quake’s magnitude. That’s just brilliant. This app also displays 24 hours worth of quake data with damage and rumble areas displayed on interactive maps.

I’m still waiting for an earthquake drinking game app. Nothing makes me want a shot of tequila more than standing in a building while everything shakes.