Vertical evacuation:: Fleeing tsunamis by moving up, not out
Stanford researchers who have studied the city have concluded that fleeing residents of a city hit by a tsunami would have a better chance of surviving the tsunami if instead of all attempting an evacuation, some could run to the nearest tall building to ride out the wave; this “vertical evacuation” could save thousands of lives, but only if the city’s buildings are reinforced to withstand both earthquakes and tsunamis.
September, fears of a tsunami prompted hundreds of thousands of residents to evacuate the coastal city. Or try to. The traffic jam resulting from the mass exodus kept most of them squarely in the danger zone, had a tsunami followed the magnitude 7.6 temblor. Stanford researchers who have studied the city have concluded that fleeing residents would have a better chance of surviving a tsunami if instead of all attempting an evacuation, some could run to the nearest tall building to ride out the wave. In the minutes after a strong earthquake struck offshore of the Indonesian city of Padang on 30
It is called “vertical evacuation” and could save thousands of lives, but only if the city’s buildings are reinforced to withstand both earthquakes and tsunamis.
Residents of Padang are trained immediately to evacuate to higher ground when they feel an earthquake. About 600,000 of the people in Padang live less than 5 meters above sea level, in the “Red Zone” for tsunamis. They have only about twenty minutes to evacuate, but on 30 September, it took them several hours. “In the event of a tsunami, hundreds of thousands of people would be at risk and could have been killed, all because they couldn’t evacuate fast enough,” said Greg Deierlein, professor of civil and environmental engineering. Indonesia is at high risk for a large tsunami, Deierlein said, and horizontal evacuation strategies alone - by motor vehicle or foot - are clearly not adequate.
Deierlein and some Stanford students are investigating how to build or retrofit buildings to withstand both the earthquake ground shaking and tsunami inundation waves of 15 to 25 feet. Deierlein led a reconnaissance team of engineers and scientists to Padang, in Western Sumatra, nine days after the September earthquake to examine how buildings fared. “It was like a big living laboratory,” he said. “We were able to see how buildings performed and how the city reacted to the threat of a tsunami.” During his visit, he was surprised by how many modern buildings collapsed. “Existing buildings can be strengthened to perform better under future earthquakes and tsunamis,” he said.
Deierlein, the John A. Blume Professor in the School of Engineering, presented this work on 15 December at the American Geophysical Union meeting in San Francisco. The reconnaissance team he led was organized through the multidisciplinary Earthquake Engineering Research Institute, a nonprofit society of technical professionals, and supported by a
