Cascadia's Fault - Jerry Thompson [140]
“And so what you’ll see,” said Lynett, “if you look at it,” and everybody clearly was glued to the screen, “you’ll see that dash of red shoot here and then bounce. And then—just eyeball right on this building.” He paused as if there was nothing else to say, then added quietly, “It would be extremely damaging ...”
It would take months of detailed side-by-side comparison to see how closely the computer simulation and the wave-tank model had matched up, but they looked remarkably similar to the untrained eyes of those of us standing poolside that day in Corvallis. In the end some combination of the two approaches would probably emerge from this experiment to create a refined and updated system for predicting the effects of tsunami attacks on other coastal communities. “You sort of have to boot-strap between a physical model in a wave tank and a computer model to validate one against the other for the things that you can test,” Chris Goldfinger explained, “and then go beyond the capabilities of either one by using them together.”
After watching Lynett’s computer simulation, it was time to play back our HD video. Because the physical model of Seaside had been built on a scale of one-to-fifty, we needed to slow the frame rate of our pictures by the same ratio—and the high-speed camera allowed us to do that—producing a slow-motion image that looked almost identical to those tragic home videos from the Indian Ocean. Now we could see the swelling mound of water as it hurtled toward the surrogate Seaside. At some critical point along the beach where the ocean bottom angled upward, the leading edge slowed down long enough for the back of the wave to catch up with the front. The swell piled up like a surfer’s dream, curled forward, and then broke under the force of gravity in a hissing bore of fast-moving water.
As it shot across the last stretch of beach toward the base of the promenade a knife-edged geyser of spraylike jets, as if from a thousand vertical fire hoses, rocketed straight up in a perfect replay of the Sumatra waves hitting the wall of a resort in Phuket, Thailand. And just as mesmerized as those poor souls who stood like backlit deer at the foot of the palms waiting to see what would happen next, we observers at the OSU tsunami basin could not take our eyes off the screen.
Having crashed over the promenade, the wave continued pounding straight at us. The street-level view from the snorkel lens revealed the Broadway canyon between the seven-story condominium complex and the beachfront hotel across the street as the roiling water lifted a toy school bus, an ambulance, and several other vehicles and swept them away—exactly the way the tsunami did in Banda Aceh. A floating garbage truck crossed the sidewalk and slammed backward like a levitated battering ram into a two-story commercial building. A few frames of video later, the wall of tumbling junk rolled right over us and the picture went dark.
“Very sobering,” said Doug Barker of the Seaside Fire Department when the video finally stopped. “It was ...” he paused, searching for the right words. “It was actually a shock. I was—it took me more by surprise than I thought it would to watch the water roll through, between those buildings. And cascade over the buildings. So, yeah, it was very eye opening, even though I’ve been dealing with it for a number of years.”
Another of the invited observers, Barbara Lence, a civil engineer from the University of British Columbia who had just completed work on a computer model of Cascadia’s wave showing how it was likely to inundate much of the village of Ucluelet on Vancouver Island, was also stunned by the video.