Engineers help earthquake-rattled Peru rebuild from the ground up
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Captions for Peru earthquake story
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A classroom in Chincha, Peru, shows damage from an earthquake that hit the area on Aug. 15 and caused more than 500 deaths. Mizzou engineer Brent Rosenblad led a team of researchers to Peru in October to provide data for rebuilding efforts.
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Rosenblad, an assistant professor, stands near rubble from Caceres School in Ica, Peru. Rosenblad and his team assess the soil to determine what areas are best for rebuilding schools, hospitals and other critical buildings.
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Daniel Huaco, a graduate student in civil engineering and a native of Peru, served as part of the team. Huaco’s father, a seismologist, established a connection with Mizzou in 2005 that led to University researchers assisting in Peru.
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This church, which is part of Socorro Hospital in Ica, Peru, serves as an example of the severe damage caused by the Aug. 15 earthquake, which had a magnitude of 8.0 — powerful enough to level buildings.
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This is another view of the same church at Socorro Hospital. Huaco says seeing such damage on the trip brought home not only the structural consequences of an earthquake, but also the cultural impact of lives, property and possessions lost.
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Temporary housing for earthquake survivors includes a tent city set up near Pisco, Peru. “These were seen all over the region,” Rosenblad says.
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Rosenblad examines a school in Tambo de Mora, Peru. The building had settled because of “ soil liquefaction,” meaning a reduction in the stiffness and strength of the soil. Soil liquefaction can cause increased damage during earthquakes.
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Jim Bay, a professor from Utah State and a colleague of Rosenblad, stands with the “drop weight” device that researchers use to create surface waves, which they then measure to determine how stiff and strong the soil is at various depths.
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Jianhua Li, a Mizzou graduate student in civil engineering, and researchers from Peru use the surface wave method to measure soil liquefaction at a site in Tambo de Mora.
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The San Clemente Church in Pisco, Peru, collapsed on its congregation during the earthquake. The church was the site of the most deaths, with 148 reported at one point.
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A broader view shows the massive damage to the San Clemente Church — the kind of damage Rosenblad and researchers would like to help prevent. “That makes this research even more ‘applied,’ ” he says, “especially when you see what kind of destruction has occurred.”
Brent Rosenblad knew what earthquakes looked like: the cracks in walls and in the ground, the leveled buildings, the weakened soil. But it took a trip to Peru to demonstrate what an earthquake feels like.
Rosenblad, an assistant professor and geotechnical engineer, led a team of Mizzou researchers to Peru in October, two months after an 8.0-magnitude earthquake rocked the country. Their goal was to assess the soil quality and provide data to help people rebuild in the smartest way possible.
While there, Rosenblad got a taste of what he has been studying all these years when a 5.1-magnitude aftershock hit. “The whole building started to shake,” he says. “That gave me a good appreciation of what it must have been like to be in a big earthquake, because that was little. That was 20 seconds of shaking, whereas that big one was two and a half or three minutes of shaking at a lot higher levels.”
That “big one” hit Peru on Aug. 15. It left more than 500 dead and countless thousands injured or homeless. It brought churches and other buildings that were hundreds of years old — and that had stayed standing during smaller quakes — to the ground.
Rosenblad and fellow researchers heeded the call for aid. They have the methods to help designers understand what sites are safe for rebuilding and what sites are likely to end in rubble in a future quake.
“There was so much damage,” Rosenblad says. “There’s a lot of work to be done.”
Research with a personal connection
The connection between Mizzou researchers and Peru became both professional and personal in 2005. Peruvian seismologist Daniel Huaco Oviedo, whose son Daniel Huaco was attending the University as a graduate student, came to visit and met with engineering and geology professors. He saw expertise that could be useful in his home country, where seismic events occur fairly regularly.
CERESIS, the regional seismology center that Huaco Oviedo directs, and Mizzou signed a “memorandum of understanding,” and a relationship was born. Rosenblad made his first trip to Peru in 2005 to talk about his research methods. Two years later, he was there to apply those methods firsthand, as he had done before in Taiwan and Turkey.
So was Daniel Huaco. As a child, he had visited earthquake sites with his father and had kept the damage he saw in his mind. Now he was helping to do something positive for his home country.
“To me it was a lab,” Huaco says. “I saw the structural behavior. I saw the failures. I saw the consequences.”
To Huaco, there’s another type of consequences, though. There is the cultural impact to which engineers are not always sensitive.
“It’s hard to think that every time we saw an empty lot, it was empty because they had already cleaned the debris,” he says. “Somebody had experienced the loss of their house, family and everything they had there.”
On the surface and far below
Rosenblad, Huaco, graduate student Jianhua Li and Utah State professor Jim Bay used the surface wave method to assess layers of soil to see how stiff they are. Ultimately, this can aid designers in knowing what sites are safe for rebuilding critical buildings such as schools and hospitals to prevent damage from future earthquakes.
Traditional methods to do this require researchers to bore deep holes into the ground and then install sensors in those holes to measure seismic waves between them. Rosenblad says the surface wave method allows for similar measurements in a less intrusive, faster and cheaper way.
The method works like this: Researchers drop a 200-pound weight from a quick-release tripod. When the weight hits the ground, it produces a range of wave frequencies. Rosenblad uses mathematical formulas to separate those frequencies and measure how fast they move through the soil. Higher frequency waves move along the surface, and lower frequencies go deeper into the soil.
By examining each frequency and how fast each wave moves through each layer of soil, Rosenblad can tell how stiff the soil is at different depths. In Peru, his team was measuring to depths of up to 100 feet.
Rosenblad does this research closer to home, too, in areas around the New Madrid fault. There, he uses a 70,000-pound truck with a hydraulic shaker that can produce waves that reach much deeper. “In New Madrid, the soils go as deep as 1,000 meters near Memphis,” he says. “There’s just not much information about those deep soil deposits.”
Of course, hauling a massive truck around Peru wouldn’t have been practical, especially because the team had limited time and wanted to assess as many sites as possible. Hence the less technical but equally effective tripod-and-weight setup.
“It’s really low-tech,” Rosenblad says, “but it gets the job done.”