Earthquake in the Midwest

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Clarice Nassif Ransom

Welcome, and thanks for listening to the USGS CoreCast. I'm Clarice Nassif Ransom. Today, April 18th, a magnitude-5.2 earthquake struck southern Illinois. I'm here today with Harley Benz, Scientist-in-Charge for the U.S. Geological Survey's National Earthquake Information Center. to fill us in on some details about the earthquake. Thank you for joining us Harley.

Harley

You're welcome.

Clarice

Tell me a little bit about what happened today.

Harley

Well, about 4:36 local time, there was a magnitude-5.2 earthquake in southern Illinois. It was about 20 miles from Olney, Illinois, and 35 miles from Evansville, Indiana.

Clarice

Is this earthquake unusual? What's the precedent for earthquakes in this area?

Harley

Well, earthquakes in this area are infrequent but not unexpected. There was an earthquake, a magnitude-5.0 earthquake, on June 18, 2002, about 20 miles from this earthquake in the same area.

Interestingly, but not surprisingly, the style of faulting from these two earthquakes were the same. And this really indicates that it's the same kind of geologic processes that produced both of these earthquakes.

Clarice

How long did this earthquake last? And how widely was it felt?

Harley

Well, this was a moderately sized earthquake. It occurred when most people were sleeping. So anybody that was woken up by this earthquake probably felt a very strong, sharp jolt. And it probably didn't last very long-probably no more than a few seconds. This earthquake was felt throughout the Central U.S. and portions of the Eastern U.S. It was felt as far west as Kansas and as far south as Georgia.

Clarice

How is this different than California earthquakes?

Harley

Well, if you take an earthquake of comparable size in California, it will only be felt regionally-probably only out to, you know, a couple a hundred miles. Whereas an earthquake of this size, we're talking about probably getting felt-reports as far as 500 miles away.

Clarice

Wow. Where can people learn more about earthquakes? And how can they report what they felt during an earthquake?

Harley

Well, people need to go to earthquake.usgs.gov. That's our main portal for earthquake information. And if they go to that main page, they'll find a link to this earthquake. When they click on that link, they can get all sorts of information and details about the earthquake, about the geology of the region, about the occurrence of earthquakes in the region.

But more importantly, they need to look on that page for a link to a thing called "Did You Feel It?" And if they go to that link, then they can report immediately what they felt. They will be asked a series of questions about  . . . did things fall off the walls? What did they feel? How long did they think they felt shaking, etcetera?

Once they've filled out this questionnaire and they submit it, they can immediately see the results of what they've posted along with other roughly 19,000 people that have already reported what they've felt.

Clarice

That's pretty amazing. That's citizen science in action.

Harley

Yeah, absolutely. It's actually invaluable information for us given that earthquakes in this part of the world are infrequent and that they're felt over such large distances. What's important is that citizens can report what they felt, which is citizen science because we use this information both to better understand the impact of this earthquake.

But it's invaluable for us to be able to use that information to predict or to model what would be the likely shaking from a larger earthquake in the area that may produce considerable damage.

So we use it for being able both to understand what happened with this event and be able to understand what we might experience in a larger, more damaging event in the future so we can do scenario modeling.

Clarice

Is there anything else that you would like to share that I forgot to ask?

Harley

Just to reiterate, I think people are always curious about earthquakes, and they really should go to earthquake.usgs.gov because it has lots of information about earthquakes in this area and elsewhere.

And so they can go there and realize that earthquakes are something that affect most of the U.S., not just the Western US problem and see where they are occurring in this part of the world. And if they are worried about earthquake preparation, there are links there on what to do and how to respond as individuals to earthquakes.

Clarice

Harley, again, thanks for joining us.

Harley

You're welcome.

Clarice

And thanks to all of you for listening to this episode of CoreCast. Again, you can find out more information about earthquakes at earthquakes.usgs.gov. CoreCast is a product of the U.S. Geological Survey, Department of the Interior. Until next time, I'm Clarice Nassif Ransom.

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Music credit:

"100 BPM-Bassline A" by frifrafro 

 Resources related to this episode:

• info about this earthquake
• earthquakes.usgs.gov
• Did You Feel It?
• USGS National Earthquake Information Center