EMILY KWONG, HOST:
For this next story, we go to the South Pole, where scientists have placed two seismometers 8,000 feet below the ice cap. These super-sensitive instruments will be used to measure earthquakes and support tsunami alerts, all at a depth that makes them the loneliest working seismometers on Earth today. And one of the people leading this project is Robert Anthony, a geophysicist with the U.S. Geological Survey. Hey.
ROBERT ANTHONY: Hey, Emily. How are you doing?
KWONG: I'm good. How are you?
ANTHONY: I'm doing great. I just got back from Antarctica about 10 days ago.
KWONG: Well, welcome. You work for USGS. Your agency runs a global network of seismometers, along with a bunch of partners, and these instruments are very cool. Can you describe what seismometers even look like and what they do?
ANTHONY: Sure. Seismometers have evolved quite a bit over the last hundred years, but our current instrumentation are kind of in silver cylinders typically, that are about maybe a foot-and-a-half tall, kind of are about the size of two Folgers coffee cans stacked on top of each other. And our vault instruments are about the size of a bowling ball.
KWONG: OK. And they're, like, designed to pick up what?
ANTHONY: I mean, specifically, we're interested in any ground motions kind of occurring across a broad range of frequencies, from about a hundred hertz, which, actually, a human could hear, all the way out to kind of the Earth tides, which happen twice a day. So very low-frequency things, things happen on scales of a day or so, all the way up to things we could possibly hear.
KWONG: Why go all the way to the South Pole to bury two more? 'Cause they are all over the world already.
ANTHONY: Right. So the South Pole is one of our most remote locations on the planet. So our next nearest seismometer used for earthquake monitoring is about 850 miles away, so that's roughly the same distance from Denver, Colorado, to Houston, Texas. So that's a - it fills a huge gap in monitoring.
KWONG: Do these two seismometers have names?
ANTHONY: They do. They do. One is called Dr. Bob, named after our former director who was at our lab for 47 years and wintered over at South Pole. And the other one is named T Storm after our 35-year quality control analyst who unfortunately passed...
KWONG: Oh.
ANTHONY: ...Away unexpectedly this past fall.
KWONG: Oh, wow. What a way to honor them. How did it feel after working on this project for three years to see those devices lowered in and to realize that it worked?
ANTHONY: It was an incredible feeling. I think it's kind of a nerve-racking experience turning them on for the first time. It takes about nine minutes for the system to boot up. And that's an excruciating nine minutes. Is it going to work or not? And I mean...
KWONG: Wow.
ANTHONY: ...This was a Hail Mary. I mean, we were up against all types of technical, logistical and political problems to just even pull this experiment off, and seeing it turn on for the first time was amazing.
KWONG: Now that the devices are up and running and recording seismic data, you have been able to see what they've found. I mean, you prepared some of that data for us to listen to. Let's play some of that.
(SOUNDBITE OF SEISMIC SOUNDS OF THE EARTH)
ANTHONY: So in that audio, at the first, you're just hearing the background hum of the Earth, mostly ocean waves. That's our largest noise source. And then you kind of hear a few thumps there. It kind of sound like timpani drums. That's the magnitude 6.1 earthquake near Okinawa, Japan.
KWONG: Whoa.
ANTHONY: Yeah. And if you listen to it super carefully...
KWONG: Yeah.
ANTHONY: ...Early on, you can actually pick up a few icequakes. They just sound like...
KWONG: Oh.
ANTHONY: ...Little cracks.
KWONG: Now, this project - these are very cool recordings from 8,000 feet below. I love that. And this project, of course, isn't fully done because you drilled the hole using hot water and set the seismometers. But you are still, as of this taping, waiting for the water to fully freeze. Is that right?
ANTHONY: That's correct. Yeah.
KWONG: It's like a giant vertical ice cube tray.
ANTHONY: That's right. And it freezes from the top down. So the seismometers are some of the last things to freeze into the ice.
KWONG: OK. And what is your hope for how this will all turn out? And how long is it going to take?
ANTHONY: So yeah. I think we'll know in the next month or so how it turned out. The concern, of course...
KWONG: Yeah.
ANTHONY: ...Is that you can experience extremely high pressures during freezing 'cause water expands as it freezes, and it could crush our devices or knock them off level. So we're not out of the woods yet. But if we, you know, survive freezing, the hope is to have the quietest seismic instruments on the planet.
KWONG: That is Robert Anthony, a geophysicist with the U.S. Geological Survey. Thank you so much for coming on the show.
ANTHONY: Thank you. Transcript provided by NPR, Copyright NPR.
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