AP Explains: How do scientists predict tsunamis?
AP Graphic © 2010 AP
To warn about tsunamis, scientists need three things: information about the earthquake, high-tech technology in the seas, and time.
With all elements in hand after today's quake in Chile, officials have issued precise warnings of a tsunami striking Hawaii — more than six hours in advance.
"What you're seeing is a very quick response to this event," Jenifer Rhoades, NOAA National Weather Service Tsunami Program Manager, told The Associated Press.
With a computer graphic showing the possible path of tsunami waves from an earthquake in Chile, Dr. Charles McCreery speaks on the phone at the Pacific Tsunami Warning Center in Ewa Beach, Hawaii, on Feb. 27, 2010. (AP Photo/Marco Garcia) © 2010 AP
In 2004, a magnitude 9 quake off the Indonesian island of Sumatra triggered a tsunami that killed 226,000 people in 12 countries. There was little measuring technology in place then, Rhoades said. And there was little time to provide warning.
Everything starts with the earthquake. Once that happens, details about the magnitude, depth and location of the quake are put into computer models to determine if there is a tsunami threat. Those results are checked with historical records to see if similar quakes have caused problems, Rhoades said. Then, researchers use physics to put numbers into equations to come up with predictions.
There is a long history of earthquakes from this part of Chile causing tsunamis in the Pacific, said Tim Dixon, a geology professor at the University of Miami.
"Most times there's been a big earthquake on that part of South America plate boundary, you get tsunamis throughout the Pacific," Dixon said.
In fact, the Chile quake-Pacific tsunami link is one of the best documented connections in geology, Dixon said.
Everything starts with the earthquake. Once that happens, details about the magnitude, depth and location of the quake are put into computer models to determine if there is a tsunami threat. Those results are checked with historical records to see if similar quakes have caused problems, Rhoades said. Then, researchers use physics to put numbers into equations to come up with predictions.
There is a long history of earthquakes from this part of Chile causing tsunamis in the Pacific, said Tim Dixon, a geology professor at the University of Miami.
"Most times there's been a big earthquake on that part of South America plate boundary, you get tsunamis throughout the Pacific," Dixon said.
In fact, the Chile quake-Pacific tsunami link is one of the best documented connections in geology, Dixon said.
Borenstein
The timing of the tsunami is based on how fast the waves move in the water. They move at 450 to 600 mph on average, about the speed of a jet. No figures are available yet for these waves.
The researchers use an extensive network of sea-level gauges and 39 deep-ocean tsunami reporting buoy stations to monitor what is happening in real time.
So far, the predictions for a tsunami in Hawaii seem to be on the mark, Rhoades said. In this part of the Pacific basin, there's been a working tsunami and seismic network for more than 40 years.
You can warn without technology just based on history and physics, but "high-tech is better because you can see it coming," Dixon said.
Seth Borenstein is an AP science writer who has been covering natural disasters since 1989.
____________________
Check here for the latest updates on the earthquake and tsunami threat.
The researchers use an extensive network of sea-level gauges and 39 deep-ocean tsunami reporting buoy stations to monitor what is happening in real time.
So far, the predictions for a tsunami in Hawaii seem to be on the mark, Rhoades said. In this part of the Pacific basin, there's been a working tsunami and seismic network for more than 40 years.
You can warn without technology just based on history and physics, but "high-tech is better because you can see it coming," Dixon said.
Seth Borenstein is an AP science writer who has been covering natural disasters since 1989.
____________________
Check here for the latest updates on the earthquake and tsunami threat.
No comments:
Post a Comment