ScienceDaily (Mar. 11, 2011) — It's being called one of the largest recorded earthquakes in world history. Also, according to Robert Yeats, "This is our wake up call."
Japan today is struggling with the aftermath of a massive 8.9 earthquake on a subduction zone, a short distance offshore, which unleashed a devastating tsunami that killed hundreds and has turned large parts of cities into rubble.
Yeats, a professor emeritus of geology at Oregon State University, said that if people didn't already get the message from recent disasters in Sumatra and Chile, they should pay attention now.
"This is an earthquake of the same type, with about the same magnitude and proximity that we face here in the Pacific Northwest from the Cascadia Subduction Zone," Yeats said. "What you are seeing in Japan today is what you will also see in our future. Except they are better prepared than we are."
One of the world's leading experts on the Cascadia Subduction Zone, OSU marine geologist Chris Goldfinger, got an up-close, personal preview of the forces he's been studying -- he was in Tokyo when the earthquake hit, ironically attending a meeting on the Sumatra earthquake.
"I'm in the northern outskirts of Tokyo and rode through the quake and continuous aftershocks ever since," said Goldfinger, a professor in OSU's College of Oceanic and Atmospheric Sciences. "The main shock lasted an entire five minutes. We were in the middle of a talk and just bailed and went outside. Here in Chiba, you could literally feel the plates grinding; the high-frequency P-wave arrival was like nothing I've ever felt.
"Then five minutes of S-waves and feeling sort of seasick," he added. "There hasn't been too much damage in Tokyo that I've seen, but watching the tsunami come in live on television in Sendai and Iwaki -- with ships washing into the town -- was amazing."
Despite the tragic loss of life and billions of dollars in damage that will result from the Japanese earthquake, Yeats said, they are as or better prepared for a disaster such as this as anyone in the world. Their technology, building codes, public education and other programs for earthquake preparation are exemplary, with scientific initiatives that date back to the 1890s.
And even though it may seem like there has been an unusually large number of earthquake disasters in recent years, Yeats said, the past decade or so doesn't really stand out all that much in a historic sense.
"It's not completely regular, there are a few clusters of disasters at some times more than others," Yeats said. "But the real message here is that the Earth is very active and sometimes violent, it always has been and always will be. We can't predict these events so we have to prepare for them."
Harry Yeh, a professor of engineering at OSU and an internationally recognized expert on tsunami propagation, also watched the events unfold on television -- with an eye toward the potential of "vertical evacuation" in coastal cities.
"It's too early to tell if vertical evacuation on a large scale would be effective in a massive earthquake such as this, though I did see many people evacuated to the top of buildings -- for example, Sendai Airport and some school buildings," Yeh said. "Japanese television repeatedly mentioned the idea and led people to evacuate to strong concrete buildings on the third floor or higher."
OSU experts have worked closely with officials in Cannon Beach, Ore., in an initiative to build what would be the nation's first structure designed specifically to resist tsunami wave forces and save lives through this concept of "vertical evacuation." Those efforts are ongoing.
Meanwhile, experts at OSU and across the Pacific Northwest are continuing to learn what they can from each disaster of this type to gain insights that might one day help save lives here.
"This is a good rehearsal for us," said Solomon Yim, a professor of ocean engineering at OSU and director of the university's Hinsdale Wave Research Laboratory, which includes one of the world's most sophisticated wave basins specifically designed to study tsunamis. "The take home message is that what just happened in Japan is going to happen here. It's just devastating.
"The forces you're seeing in Japan are similar to what happened in Indonesia," Yim said. "You saw cars and boats and debris slamming into structures and bridges, those are the types of forces we need to learn more about in building tsunami resistant structures."
Improvements in understanding subsea bathymetry would be helpful, OSU experts said, as well as how wave forces will translate into onshore runup once they hit land. More work with public outreach and ocean mapping are also needed, they said.
Story Source: The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Oregon State University.