Tsunamis – Quakes

music
ambience: underwater earthquake

Tsunamis, like the one that devastated parts of Southeast Asia, are often caused by earthquakes. But even if a quake takes place under the ocean, it doesn’t necessarily cause a tsunami. I’m Jim Metzner, and this is the Pulse of the Planet. Right now we’re listening to the sounds of an underwater earthquake.

Ambience: underwater earthquake

“Whether or not an earthquake produces a tsunami depends on whether or not the earthquake changes the shape of the ocean bottom, and you can have a big earthquake that doesn’t really change the ocean bottom shape much and doesn’t produce much of a tsunami. “

Gerard Fryer is an associate geophysicist and tsunami Researcher at the University of Hawaii. He says predicting a tsunami can be a tricky business.

“You can have a small earthquake that ruptures all the way to the sea floor that produces a big tsunami. So that’s a real problem. We can’t tell just from the size of the earthquake how big the tsunami’s going to be. The only thing we can say for sure is that if the earthquake’s bigger than about 8.5, we know we’ve got a tsunami that’s going to travel all over the ocean. A lot of the warning problem is to figure out whether the tsunami is big enough to worry about. Another challenge is trying to track which way the tsunami’s waves will travel. The way to think of a tsunami that’s generated by a big earthquake in one of these deep ocean trenches, like happened in the Indian Ocean, is it’s rather like rolling a log into water. You get big waves off the middle of the log, and you get small waves off the ends of the log. But those big waves, they will travel all the way across the ocean. They will bounce off the far side. They’ll then travel to the other side of the ocean and bounce back again. In fact, this Indian Ocean tsunami, it escaped from the Indian Ocean. It was actually measured in the Pacific. It was measured in the Atlantic.”

Tsunamis - Quakes

For an earthquake to produce a tsunami, it has to change the shape of the ocean's bottom.
Air Date:08/19/2011
Scientist:
Transcript:

music
ambience: underwater earthquake

Tsunamis, like the one that devastated parts of Southeast Asia, are often caused by earthquakes. But even if a quake takes place under the ocean, it doesn't necessarily cause a tsunami. I'm Jim Metzner, and this is the Pulse of the Planet. Right now we're listening to the sounds of an underwater earthquake.

Ambience: underwater earthquake

"Whether or not an earthquake produces a tsunami depends on whether or not the earthquake changes the shape of the ocean bottom, and you can have a big earthquake that doesn't really change the ocean bottom shape much and doesn't produce much of a tsunami. "

Gerard Fryer is an associate geophysicist and tsunami Researcher at the University of Hawaii. He says predicting a tsunami can be a tricky business.

"You can have a small earthquake that ruptures all the way to the sea floor that produces a big tsunami. So that's a real problem. We can't tell just from the size of the earthquake how big the tsunami's going to be. The only thing we can say for sure is that if the earthquake's bigger than about 8.5, we know we've got a tsunami that's going to travel all over the ocean. A lot of the warning problem is to figure out whether the tsunami is big enough to worry about. Another challenge is trying to track which way the tsunami's waves will travel. The way to think of a tsunami that's generated by a big earthquake in one of these deep ocean trenches, like happened in the Indian Ocean, is it's rather like rolling a log into water. You get big waves off the middle of the log, and you get small waves off the ends of the log. But those big waves, they will travel all the way across the ocean. They will bounce off the far side. They'll then travel to the other side of the ocean and bounce back again. In fact, this Indian Ocean tsunami, it escaped from the Indian Ocean. It was actually measured in the Pacific. It was measured in the Atlantic."