Rowena Lohman studies quiet movements of the Earth to gain a better understanding of when the “big one” will hit.
“The holy grail of seismology is to identify earthquake precursors, and fault creep events are some of the most promising recent discoveries,” says the assistant professor of earth and atmospheric sciences.
Most people know that earthquakes happen on fault lines in the Earth’s crust. Normally, the upper few kilometers of the tectonic plates are “locked” together at a fault, even though they are being pulled past each other in the long term. Stress slowly builds until the frictional resistance is overcome, the plates suddenly slip, and buildings fall.
But scientists—including Lohman’s husband, Matt Pritchard, also an assistant professor of earth and atmospheric sciences at Cornell—recently learned that sometimes, plates slip slowly and release that built-up stress without destructive earthquakes. People don’t feel it, but satellites and strain gauges can detect the change on the earth’s surface. These “silent” quakes could potentially increase stress in some areas, leading to giant temblors—but the interactions aren’t quite clear yet. “The lack of a correlation is really because we’ve just started seeing them,” says Lohman. “Describing what’s going on is step one.”
With a better understanding of the role of slow slip events, says Lohman, the U.S. Geological Survey could incorporate them in its seismic hazard map. That could improve the response to large earthquakes in places such as Southern California, where Lohman, from a military family, has spent more time than anywhere else. She earned her undergraduate and graduate degrees from Caltech and completed a postdoc at the Woods Hole Oceanographic Institution, before returning to California for a postdoc at NASA’s Jet Propulsion Laboratory.
Lohman joined the faculty at Cornell in the summer of 2007. “I’m happy to get out of L.A.,” she says. “I’m still getting used to the fact that I don’t have traffic helicopters flying over head every few hours.”
Lohman credits her mother—a high school science teacher—for her interest in earth science. She encouraged Lohman, still a high school student, to participate in a summer field research program at the Icefield Research Program in Juneau, Alaska. “After that, there was no way I was going to do anything else,” she says. “The camping, the science, the physical exercise—I was completely hooked at that point.”
Now she has to laugh, Lohman says, because she spends most of her time behind a desk, analyzing data at a computer. Though she still occasionally does field work. In February 2008, she helped resurvey an area near the San Andreas Fault.
Her interest initially was glaciology. She chose Caltech for its programs in Antarctica. She went twice, for three months and again for six weeks, as a research assistant. It wasn’t until grad school, that she started working on earthquake-related problems. “I’m coming full circle now with students interested in working on glaciers,” she says.
In addition to Active Tectonics, she’s looking forward to someday teaching Geophysics and Geomorphology. “Earth science is a fascinating field,” she says, “especially for people seeing all the new things happening now and reliving that with the students.”
Prof. Lohman's Web page
