Thu. May 26th, 2022

head shot of Chukwuebuka Nweke

Chukwuebuka Nweke.

Even as a child 8,000 miles away in Nigeria, Chukwuebuka Nweke remembers the 1995 Kobe earthquake in Japan.

“It was a massive, devastating event,” Nweke recalled in an interview earlier this year. “It was probably the first earthquake I saw (video) footage of.”

Now Nweke, a geotechnical civil engineer, is a new assistant professor in the Sonny Astani Department of Civil and Environmental Engineering.

Seismic hazard modeling – how the earth shakes and how it varies from place to place – is one of his key focus areas with the aim of helping us allocate priority resources to the most vulnerable structures. “Some places can have a lot more damage depending on a number of things, including what’s underground and what kind of buildings there are,” he said. “It combined with information such as what kind of service the structure provides or its population density helps determine the level of risk.”

For example, Nweke said that if an earthquake occurs in the middle of the desert with a low or zero population, even very large quakes would not be of great concern. But in the LA basin, it’s a different story, Nweke said. “I specialized primarily in seismic response at the site, where I try to see how much an earthquake intensifies in areas that are softer, such as Los Angeles – the entire basin from Westwood to Orange County is very soft relative to the adjacent mountains, ” he said.

Nweke, whose scientific curiosity originally stemmed from watching various Discovery Channel series about meteors and the impact of dinosaurs, said that Los Angeles is of particular interest because of its geomorphology (physical features of the earth’s surface and their relation to its geological structures), which are the result of millions of years of growth and change. That combined with its high population density creates heightened concerns about the “big one” approaching.

Nweke said: “Our goal is to better understand this pool-to-pool amplification effect and better design for it. It also means knowing what you are designing towards. How much the shaking is going to happen, where is it more dangerous, and how will people in society be affected. ”

To better understand this concept, Nweke said, think of a bowl of Jell-O. “If you shake the bowl with Jell-O, you get a little mess, depending on how wildly you shake it. This is a good analogy for amplifying the earthquake in sedimentary basins like Los Angeles. ”

Biocemented materials

Nweke’s work also focuses on the study of biocemented materials, which are materials that use enzymes such as urease to produce strong, sustainable building materials with minimal impact on the environment.

“Basically, we try to go from sand to stone. In geology, it takes millions of years before that happens, ”he said. “But we use enzymes to speed up the process of creating an environment where we can precipitate (solidify) calcium carbonate out of solution and make it bind to sand – essentially going from sand to sandstone.”

Nweek’s focus is on understanding how this material behaves – strength, resilience and resistance – and how it degrades. “Once we understand that, we can apply the material to construction situations where we don’t have to use concrete,” he said. “Concrete is a fantastic material, but also very environmentally damaging.”

As The Guardian noted in 2019: “If the cement industry were a country, it would be the third largest carbon dioxide emitter in the world.”

Nweke, whose father was also a civil engineer in Nigeria, said that when we better understand biocemented materials, we can find out where we can use them and where they will not be as viable.

“The overall goal of my research is to create a multi-hazard framework that includes the pre, current and after-effects of seismic and other hazards — such as wildfires,” he said. “I want to create an environment where we are more resilient, we are flexible, better designed – essentially increasing life security and improving the lifestyle of the human population.”

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