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Shallow Rayleigh-wave Tomography Using Traffic Noise From Long Beach, California, USA
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 78th EAGE Conference and Exhibition 2016, May 2016, Volume 2016, p.1 - 5
Abstract
Using recordings from a dense seismic array in Long Beach, California, USA, we demonstrate the effectiveness of using traffic noise for shallow subsurface imaging. Using the ambient-noise cross-correlation technique at frequencies greater than 3 Hz, we extract fundamental- and first-order-mode Rayleigh waves generated by Interstate 405 and local roads. We use group travel times associated with the fundamental mode in a weighted straight-ray tomography procedure to produce group velocity maps at 3.0 Hz and 3.5 Hz. The velocity trends in our results correspond to shallow depths and coincide well with lithologies outlined in a geologic map of the survey area. The most prominent features resolved in our velocity maps are the low velocities in the north corresponding to less-consolidated materials, high velocities in the south corresponding to more-consolidated materials, a low-velocity zone corresponding to artificial fill in Alamitos Bay, and a low-velocity linear feature in the Newport-Inglewood Fault Zone.