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Hey, short wavers, Emily Kwong here. And Regina Barber back with our next installment of our summer sea camp series.
I love this series. It's been so fun. It has been.
Where are we going today? Rock bottom, Emily.
Rock bottom. Oh. We're in the hadle zone.
The deepest zone that we are aware of, people also refer to it as the trenches, and there aren't a lot of these places in the oceans.
That's Noelle Boland. She's our go-to marine biologist from the National Oceanic and Atmospheric Administration.
And she says the Hadal Zone is any area.
6,000 meters below sea level and deeper.
How deep does it go? Yeah. of the trenches can vary, but the deepest one, the Mariana Trench, is almost 11,000 meters or nearly seven miles deep.
That's very far. I've heard of the Mariana Trench, but now that I imagine my seven mile run downwards, that's quite deep.
Yeah, I do not think I've ever run that far, but I want to.
It makes sense that this is a really tough place to study, let alone get humans down there.
But we're going down there today. Yes. By hearing from Dawn Wright, one of less than 30 people who visited the deepest point in the Mariana Trench. a place known as Challenger Deep.
Let's go. Descending in a submersible is not unlike being in a space capsule in many ways.
You're in a very small space. not enough room to stand up.
It was very slow and very peaceful and very calm.
And as we got to around 800 to 900 meters depth, that's when we lost light. we were treated to a fireworks show of sorts. worms, jellyfish, anglerfish.
They use bioluminescence to communicate with each other.
Dawn's traveling companion, pilot Victor Vescovo, started flashing the lights of their submersible.
And... We saw them flash back. But Dawn didn't travel 10,000 meters or 6.7 miles underwater just for a light show.
Dawn is a marine geographer. I study the rocks and the motion at the bottom of the ocean.
So that we have a better idea of how the earth works at the bottom of the sea.
On this particular mission, Dawn was testing a new sonar device that operates at extreme depths and pressures with the goal of creating a detailed map of the seafloor.
Which is important to know because the geologic activity on the seabed is the most exciting. the most perplexing and the most important.
Most important because it's where underwater earthquakes start, which can lead to tsunamis.
Understanding the seafloor helps scientists and policymakers keep people safe.
And that's one reason Dawn and many other scientists are involved in a global effort. led by the Nippon Foundation and Jebco, called Seabed 2030.
The goal of Seabed 2030 is to give us a... detailed modern map of 70% of the planet that we have known very, very little about.
Today on the show, cataloging the unknown.
Why knowing more about the farthest reaches of the ocean floor is important for life here on land. from tsunami safety to renewable energy, and even the internet.
I'm Regina Barber, and you're listening to Shortwave, the science podcast from NPR.
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Okay, Dawn, just to start, how does one map the seafloor?
It works through sonar, sound navigation and ranging.
And this is because sound is the most effective way of sensing the undersea environment.
So the basic principle is to send pulses of sound from an instrument or a ship down to the ocean floor We can time the amount of time that it takes for the pulse to reach the ocean floor and come back to the instrument.
And that time is turned into a distance.
So that is where we get our depths. And then we have all kinds of sophisticated algorithms for making sure that we're getting the proper time because the speed of sound changes according to the temperature and the salinity of the water, which varies throughout the oceans.
Yeah, of course. Okay, so from what I understand, sonar of the seafloor, that's what let scientists in the 60s put words to how formation happened.
Right. Like things like ridges, trenches and even like the Ring of Fire, the most seismically and volcanically active area of the world. where the Pacific tectonic plate meets the other tectonic plates where I used to live.
So the seismic activity, that's a big reason for mapping the ocean floor, right?
Yes, mapping the ocean revealed all of those features.
It revealed the large chains of volcanoes, which are known as the Mid-Ocean Ridge.
In fact, it was the work of Marie Tharp.
In particular, she mapped all of the world's oceans and oceans those mid-ocean ridges, those large trenches. where a lot of the earthquakes occur and also the very large scars on the seafloor that are known as fracture zones.
These are places where seafloor is sliding past each other.
So this is like the San Andreas Fault underwater.
So these are all the big, major tectonic features that popped out in beautiful, glorious detail and reveal themselves once we started getting these maps of the ocean floor.
And those features, they can also lead to things like tsunamis?
Yes, so tsunami... comes about as a result of a movement on the floor of the ocean that's expressed in a fault, when you have that disruption on the ocean floor, The water above the ocean floor gets severely disrupted as well. and generates these large, long wavelength waves that are essentially the tsunamis. we can make sure that we are monitoring those areas.
But even more importantly, We must understand what the bathymetry is there.
Okay, and what's bathymetry? If people understand topography on land, which is how elevation changes, over certain distances.
That's what bathymetry is on the sea floor.
So it's undersea topography. In your old home of Washington, and certainly in Oregon, there is a Cascadia subduction zone. that is not far off the coast of Oregon and Washington that can generate these types of tsunamis and the warning time will be very, very short.
So we understand what the bottom of the seafloor looks like in those coastal areas.
That helps us to... plan more effectively for where people should evacuate or how they should evacuate, what roads should they take, what roads they should avoid, how to get to higher land as quickly as possible.
So that's one of about 50 reasons why we should map the ocean floor.
And what are some of those reasons? Another very, very important reason reason is we're looking to the ocean now for energy more.
Wave energy, for instance. or wind energy, and we are citing wind turbines on the ocean floor.
So we need to know what the ocean floor looks like. which areas are flat, for instance, and also what the composition of those areas is.
Is it sandy? Is it silty? Is it rocky? What are the best places for us to anchor that type of alternative energy infrastructure?
That's a huge issue. use of ocean mapping.
One more is for habitat. We enjoy fish and other types of protein from the ocean.
Right. A lot of it is near or on the ocean floor.
And in order to monitor and to protect the habitat of those fisheries, that's a huge use for seafloor mapping.
We need to have the seabed mapped for all kinds of different purposes.
One of which is the whole idea of internet traffic.
Right. Because so much of our internet connections actually go through these cables that are like on the seafloor, these submarine cables.
And your company... Esri actually deals with some of those maps.
Exactly, yeah. At our company, we deal with anything that can be mapped.
We have a beautiful... animated map of all of the world's submarine cables that help people to understand all of this infrastructure, all of these processes.
And our maps show that 99% of all of our internet traffic is carried by these submarine cables.
So modern life, everything from podcast to Pokemon Go account to WhatsApp group. to all of the streaming videos.
I'm thankful for my BritBox subscription so I can get my British Murder mysteries?
Yes. I'm thankful to the ocean floor for that.
Yeah. And this all leads... to the Nippon Foundation Jebco Project Seabed 2030.
And you're part of this strategic advisory group for this effort to map the entire higher seafloor by 2030.
And as of June 2025, you're at 27.3%. How is this going?
So we have a long way to go, but we have also come up from around 6% just in the last few years.
We're also working with various industries that have bathymetry data that they have not released yet.
And the hope is that we can very quickly get to 40% if we can get a lot of these companies to release their data and to make it public.
We're hoping to get very close. by 2030, but the work, all of this work is going to continue beyond 2030 for sure.
Yeah, and I know one of the nonprofits involved in this effort is Map the Gaps, which is focused on making sure data is... open access and that there's increased equity and awareness of seafloor mapping and the whole process.
And part of this means getting anyone with like a boat to help map the seafloor as they're out and about, which I think is really cool.
Yes, yes, that's part of it too. In fact, there's the expression cheap and deep. where you don't have to have a huge sophisticated research vessel or a $20 million robot to map the ocean floor, everybody can contribute What if the seafloor isn't totally mapped 30, 40, 50 years from now?
What are the consequences of not mapping that seafloor?
We are going to be putting our public safety at risk by not having the proper safety understanding of not only tsunami run up, but storm run up along our coasts.
We are going to be running the consequences of not fully understanding sea level rise and shoreline change.
We could be losing valuable fisheries forever.
We are going to have a hard time with the security of our ports and If we do have additional accidents or emergencies at sea, How are we going to find things?
We still have not found MH370. That airplane that was lost.
Oh, geez. There was never going to be a very... quick way to find or to rescue the Ocean Gate Titan submersible.
And those are just two... individual examples.
So all of these areas, all of these reasons for mapping the ocean floor, the longer that it takes us To get to close to 100%, we are just going to be playing with fire, so to speak.
Dawn, thank you so much for talking to us about mapping the seafloor.
Oh, thank you so much. I really enjoyed this.
Before we head out, I want to encourage you to sign up for our CCAMP newsletter, where we go deeper with all the cool science we learn each week.
There's extra research, animals, comics, even fun games.
Sign up at npr.org slash ccamp. This episode was produced by Burleigh McCoy and edited by our showrunner, Rebecca Ramirez.
Rebecca and Anil Oza checked the facts originally.
Burleigh checked the CCAM version of this episode.
Robert Rodriguez was the audio engineer.
I'm Regina Barber. Thank you for listening to Shortwave from NPR.
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