Register for an account


Enter your name and email address below.

Your email address is used to log in and will not be shared or sold. Read our privacy policy.


Website access code

Enter your access code into the form field below.

If you are a Zinio, Nook, Kindle, Apple, or Google Play subscriber, you can enter your website access code to gain subscriber access. Your website access code is located in the upper right corner of the Table of Contents page of your digital edition.


#84: Yardstick for Killer Waves

By Richard MorganDecember 16, 2010 6:00 AM


Sign up for our email newsletter for the latest science news

When a magnitude 8.8 earthquake ravaged Chile in February, the Pacific Tsunami Warning Center in Hawaii put most of the Pacific Rim on alert. With no way to know how big the resulting ocean wave might become, the center’s geophysicists had no choice but to prepare for the worst.

Aiming to do better, Tony Song of NASA devised a much more precise tsunami prediction system based on GPS readings; he tested it successfully for the first time this past year. Song’s technique predicts the exact scale of a tsunami by tracking ground motions to estimate how much water has been displaced on the ocean floor—and, by extension, how much energy is feeding the wave.

When the Chile earthquake struck, Song’s system showed that an underwater fault had slipped almost 10 feet, potentially enough to produce a tsunami several yards high. But then Song crunched the numbers and saw that the tsunami scored only a moderate 4.8 on his 10-point intensity scale, so he correctly predicted that it would not spread far beyond Chile.

Soon nations around the world, including India, Italy, Portugal, and Taiwan, began calling Song to inquire about his prediction system. He envisions eventually deploying one GPS receiver for every 12 miles of coastline to track the strength of developing tsunamis. “GPS adds a new dimension, a more complete picture that is very fast,” Song says. “We will tell not just what the tsunami is, but what it will be.”

3 Free Articles Left

Want it all? Get unlimited access when you subscribe.


Already a subscriber? Register or Log In

Want unlimited access?

Subscribe today and save 50%


Already a subscriber? Register or Log In