Tsunamis – Origins

Music

ambience underwater earthquake

If a huge rock lands in deep water it’ll make waves. That’s one way to create a tsunami, but not the only way. I’m Jim Metzner, and this is the Pulse of the Planet.

“There are a variety of ways that a tsunami can form. The commonest is from an earthquake.”

Gerard Fryer is an associate Geophysicist and Tsunami Researcher at the University of Hawaii. The sound we’re listening to is an earthquake recorded underwater.

“In an earthquake, the shape of the ocean bottom was changed for a distance of about 1,000 kilometers and about 100 kilometers across, so there was a huge uplift of the ocean bottom. And that uplifted the water faster than the water could flow out of the way. So there was this extra lump of water and it collapsed, and you get a tsunami. So that’s the way earthquakes make tsunamis. But tsunamis can also be generated by landslides, and that’s a lot easier to understand. If you have a landslide that slides down into the water, water has to get out of the way, so it pushes up a lump of water in front of it and sucks water down behind it. And, again, you have an unevenness in the sea surface, and that will oscillate and produce a succession of waves. One of the ‘end of the world’ type scenarios is if the earth gets hit by a giant asteroid, and if the asteroid hits an ocean, then you’re gonna punch a hole in the ocean. And then, the water’s going to flow in, it’s going to oscillate, and you’ll get a tsunami from that. One that’s a little less farfetched is volcanic tsunamis. There’s a bit of an argument about what causes these. The great tsunami from the eruption of Krakatau in 1883 was probably from a collapse of the eruption column that basically-the volcano puts a lot of material into the water all at once, and that displaces water. And that gives you a succession of waves.”

Pulse of the Planet is made possible by the National Science Foundation. I’m Jim Metzner.

Tsunamis - Origins

Most tsunamis are caused by earthquakes, but that's not the only cause of one of nature's most destructive forces.
Air Date:08/14/2008
Scientist:
Transcript:

Music

ambience underwater earthquake

If a huge rock lands in deep water it'll make waves. That's one way to create a tsunami, but not the only way. I'm Jim Metzner, and this is the Pulse of the Planet.

"There are a variety of ways that a tsunami can form. The commonest is from an earthquake."

Gerard Fryer is an associate Geophysicist and Tsunami Researcher at the University of Hawaii. The sound we're listening to is an earthquake recorded underwater.

"In an earthquake, the shape of the ocean bottom was changed for a distance of about 1,000 kilometers and about 100 kilometers across, so there was a huge uplift of the ocean bottom. And that uplifted the water faster than the water could flow out of the way. So there was this extra lump of water and it collapsed, and you get a tsunami. So that's the way earthquakes make tsunamis. But tsunamis can also be generated by landslides, and that's a lot easier to understand. If you have a landslide that slides down into the water, water has to get out of the way, so it pushes up a lump of water in front of it and sucks water down behind it. And, again, you have an unevenness in the sea surface, and that will oscillate and produce a succession of waves. One of the 'end of the world' type scenarios is if the earth gets hit by a giant asteroid, and if the asteroid hits an ocean, then you're gonna punch a hole in the ocean. And then, the water's going to flow in, it's going to oscillate, and you'll get a tsunami from that. One that's a little less farfetched is volcanic tsunamis. There's a bit of an argument about what causes these. The great tsunami from the eruption of Krakatau in 1883 was probably from a collapse of the eruption column that basically-the volcano puts a lot of material into the water all at once, and that displaces water. And that gives you a succession of waves."

Pulse of the Planet is made possible by the National Science Foundation. I'm Jim Metzner.