Fiber Optic Seismic Array in Pasadena Tracks Rose Parade

New seismic array is sensitive enough to distinguish individual floats and bands. In November, Caltech and the City of Pasadena unveiled a new citywide fiber optic earthquake detector capable of mapping how temblors are shaking the city at millimeter-scale resolution. A month and a half later, while millions of spectators watched floats and bands parade down Colorado Boulevard, Caltech researchers watched the seismic signal of those floats and bands, captured in fine detail by the array. "The Rose Parade is an amazing cultural event in Pasadena, and the floats and bands run right on top of our newly established fiber seismic array," says Zhongwen Zhan (MS '08, PhD '13), assistant professor of geophysics and the lead researcher on the fiber optic project. Zhan is the corresponding author of a paper about the Rose Parade's seismic signature, published on May 5 in Seismological Research Letters . The Pasadena Array takes advantage of two currently unused, or "dark," strands of the City of Pasadena's fiber optic cable network, which is typically buried just below ground and stretches in a large loop around the city. Two laser emitters shoot beams of light through the cables.