Episode 41 - Creating a tsunami — on a centrifuge with Maggie Exton
On this week’s episode host Dan Zehner talks with Maggie Exton, a PhD candidate at Oregon State University focusing on tsunami inundation. She talks about her interest in engineering and her current research project: creating tsunamis on a centrifuge. She says her father, a sculptor, helped interest her in building things as a kid. As an undergraduate at Rensselaer Polytechnic Institute she studied materials science and engineering. Also at RPI she earned her master’s degree in geotechnical engineering. She learned to love centrifuge modeling at RPI, where she modeled levees. It is a heady feeling being in graduate school and focusing primarily research, she says. It can be confusing trying to figure out everything that’s going on. Although she’s working on her PhD with tsunami experts at Oregon State University (one of the eight NHERI facilities), she and her research group are performing some of their experiments at the Center for Geotechnical Modeling at UC Davis, another NHERI facility. She describes working with the large, nine-meter radius centrifuge at the CGM, where her research team is building a “tsunami box” to spin on the centrifuge. The spinning centrifuge can model – very quickly – the effects of a tsunami wave on soil. They model the tsunami runup in .1 seconds, she says. The centrifuge tests at 40g, spinning at 63rpm. Her team is the first to model a tsunami on the centrifuge, and building the tsunami box is a trial-and-error process. She describes the intricate experiment, which must have a reservoir of water, a gate to release water over the soil sample, and then another gate to let the water flow out. To make it work, she says, there’s intensive collaboration between her research group at OSU and the faculty at UC Davis. The tsunami box needs to be adjustable so researchers can configure it as they continue their experiments. In the initial experiments, she says the flow was too fast, 10 meters per second. Five meters per second is preferable for emulating the tsunami wave. As the tests take place, a video camera records the action – which the researchers play back in slow motion. They added flow tracers, tiny Styrofoam balls, to track the exact movement of the water in the centrifuge. This summer Exton will be back at UC Davis for another round of centrifuge testing. After that, she’ll analyze the resulting data. Exton is intrigued by the variety and pace of research underway at UC Davis – and especially the gigantic centrifuge. It’s so big, she says, it’s humbling.