Emphasizing the science behind tsunamis, Northwestern’s resident expert discussed the causes, effects and lessons of the Sumatra disaster Monday at Harris Hall.
Geology prof. Emile Okal, an internationally recognized tsunami researcher, provided a simplified version of the complex scientific phenomenon that has killed more than 150,000 in Southern Asia.
Okal, who has researched the effects of tsunamis in Papua New Guinea, Polynesia, Greece and Turkey, held the lecture in response to the recent demand for his expertise.
“Since I’ve talked to a number of journalists in the past week, I thought why not talk with people in the (academic) field,” he said, “There’s always room for more discussion, and in a community like this, we can always bridge the gap between the technical and social elements of the tsunami.”
Using charts, diagrams and real-life examples, Okal illustrated the origin, power and effect of the Sumatra tsunami, which was caused by the strongest earthquake in 40 years.
“This event is a goldmine for future scientific research,” he said, adding that such a tsunami occurs once in 400 years.
Proper warning procedures, Okal explained, is the most important means in preventing a similar disaster. The process, however, is extremely complex. Tsunamis occur when the ocean level rises a few centimeters over a wavelength of several hundred miles, thus they cannot be detected by eyesight.
“The idea of tsunami warnings sounds simple, but it is a real challenge,” he said, describing the uncertainty of predicting ocean activity following seismic activity. “False alarms are the last thing you want in the tsunami business because after the third, fourth, fifth alarm, Peter doesn’t cry wolf anymore.”
To improve this process, Okal described forms of underwater, satellite and atmospheric detection. Okal himself also has developed a mathematical method in detecting tsunamis.
“We can in real time and in the mathematical process better detect, locate and estimate seismotic movement,” he said. “Even a station that is far inland should be able to warn coastal areas.”
An example of effective tsunami detection, he added, is the Pacific Tsunami Warning Center, which protects Pacific Rim countries in the event of seismic activity. After detecting an earthquake, the PTWC has 30 minutes to assess its risk and order coastal evacuation. Ironically, after detecting the Sumatra earthquake, the PTWC was unable to warn South Asia of the impending danger.
“This is not a simple task because warnings must be well-proven and reliable communication between two countries,” Okal explained.”This has to rely on a detailed, complex infrastructure that costs a lot of money and hasn’t been built.”
Given the challenges of creating a worldwide communication infrastructure, Okal stressed the importance of education in saving lives.
“The message is very simple,” he said. “If you’re on the beach and you feel any earthquake, don’t take a chance. Run for the hills.”
According to audience member Tiffany Sakato, the lecture shed a new light on the Sumatra disaster.
“I definitely appreciate how Prof. Okal was able to put into context the magnitude of this disaster,” said the Medill junior, noting Okal’s comparisons of the tsunami to previous tsunamis and earthquakes. “The media does a good job of covering the human element of the tsunami but don’t really have the expertise to explain it in a technical context. He did it in terms I can understand.”
Reach Jean Luo at [email protected].
