Shaken, Not Stirred--3.6 Earthquake in Maryland

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Scott Horvath: Welcome and thanks for listening to the USGS CoreCast. My name is Scott Horvath, and this morning we're speaking with Mike Blanpied of the U.S. Geological Survey Earthquake Hazards Program. We're going to talk a little bit about the 3.6 magnitude earthquake that struck Maryland this morning.

And we'll just go ahead and get right into it. Mike, thanks for joining us this morning.

Mike Blanpied: Oh, my pleasure.

Scott Horvath: So obviously there was an earthquake event today in the Maryland area, I believe, and we'd like to know a little bit more about the earthquake event itself. Could you tell us a little bit about what happened this morning?

Mike Blanpied: Well, a lot of people in the area were woken up by this earthquake. It happened at four minutes after 5 am. And the epicenter was right around Gaithersburg, Maryland. It was a shallow earthquake of magnitude 3.6, and that's obviously big enough to be fairly widely felt in the area.

Scott Horvath: How widely felt was this earthquake? It doesn't seem--I mean, it seems sort of odd that a 3.6 earthquake would be felt so widely. Can you explain a little bit why it was felt like that?

 01:07

Mike Blanpied: Well, as you know, an earthquake creates seismic waves that then travel out through the rocks in the area. In this case, they were still strong enough out the distances of Southern Pennsylvania, even out to West Virginia, and obviously in the Maryland and District and Virginia areas. And it looks like thousands of people felt the earthquake. Some were woken up, and those who were awake in the area definitely did feel that.

Scott Horvath: So, Mike, can you tell us a little bit about the history of earthquakes in this area and if it's common to have such an earthquake of this magnitude?

Mike Blanpied: This is actually the largest earthquake that has been recorded in this area right around Washington D.C. since we've been recording earthquakes. We've had smaller earthquakes, some of which were felt, and we've had earthquakes up to magnitude, oh... Listeners may recall that back in 2004, there was a magnitude 4 earthquake down in Central Virginia that was widely felt, and there have been such earthquakes in Southern Pennsylvania.

 02:09

The very biggest earthquake in Virginia that we know of was back in the late 1800s. It was a magnitude 5.7 earthquake in Giles County. And that was, of course, widely felt by the population of the area.

Scott Horvath: So you mentioned that 5.7. If something like that was to occur today, how widely felt would that be? I mean, that's something typical that you might hear about in California but not on the East Coast.

Mike Blanpied: Right. California does have the largest number of earthquakes--that and Alaska--but here in the East Coast we do get occasionally large earthquakes.

You may recall there was an earthquake of magnitude 5 in Southern Quebec just a couple of weeks ago, and there have been earthquakes in really all over the east, one year or so where they hit the news.

The thing about the east is that the rocks under our feet are old and cold, and so when an earthquake does occur those waves travel very far and earthquakes are very widely felt. That Quebec earthquake of magnitude 5 was actually felt throughout several provinces in Canada and 19 states in the U.S.

 03:15

Scott Horvath: Wow, that's quite a distance. So this morning I was listening to the local radio station when they were talking about the earthquake and one of the things that struck me is that they were saying, "What do we do in an earthquake? Do we put ourselves up against a frame of the door or something?"

So it seems that there's a little bit of preparedness information that could be bestowed upon people that live around this area. Is there something that people can read or they can learn more about being prepared for an earthquake?

Mike Blanpied: Yes, there certainly is. There's lots of earthquake preparedness information. Like you say, it's not as widely known in the East Coast as it would be in more earthquake-prone areas.

I'll say a couple of things. One is, during an earthquake, the most important thing you can do is duck, cover and hold on. It's get down, get underneath something, and hold on so if anything does fall off shelves, ceiling tiles falling, furniture falling over or so forth, that you're protected. The most important thing to do during those few seconds of shaking.

 04:16

There is quite a bit of information on the Web available for people to think about what to do before earthquakes, to make sure that they're safe during an earthquake, and then immediately afterwards. A good place to start is on our website. The exact URL is earthquake.usgs.gov/prepare.

Scott Horvath: Great. I appreciate that. How can people report what they felt to USGS? And we know in the past few report earthquakes. How can they report that and why is that kind of information so important to USGS?

Mike Blanpied: Well, here in the east we don't have a lot of seismometers. We have recorded this earthquake very well by seismometers located at some distance. But it turns out that people make actually very good seismometers, too, and they are certainly densely distributed in the area unlike the seismometers.

 05:05

We have a feature on our Web called "Did you feel it?" and you can actually fill out a short form that asks you where you are located, what you were doing, where you were, and what you experienced, and your answers actually contribute to a map that is on the Web and you can see the distribution of felt reports in the area. The last time I looked, a few minutes ago, we were approaching 7,000 responses from people in the several state area right around here.

Scott Horvath: Before I end this podcast, is there anything else that you'd like to add?

Mike Blanpied: Well, people in this country often think of earthquakes as being really a West Coast thing—a California problem. But it turns out that actually earthquakes are widely distributed in the country.

The USGS prepares a national seismic hazard map, also available on our website for those who are interested, and it shows that at least 37 states have an appreciable seismic hazard, and that includes Virginia, Maryland.

 06:01

And this earthquake really comes just as a reminder that earthquake hazards do exist in other places and it pays to take a little bit of time to prepare, be aware and so you're both safe and comfortable during the earthquake.

Scott Horvath: Great! Thank you very much, Mike. I appreciate your time. I know that you are a busy man. And this is certainly going to be one of those events that people well be talking about for quite some time around the area.

Mike Blanpied: We certainly will. Good talking with you.

Scott Horvath: Thanks again.

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Related Links:

• 3.6 Magnitude Earthquake details
• Did You Feel It?
• Earthquake Preparedness
• USGS Twitterstream (@USGS)
• Twitter Earthquake Detector (@USGSted)