Mapping Faults in Urban Areas, Northern California

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Lidar remote sensing has become a vital tool for mapping active faults in areas where the ground surface is obscured by vegetation. Fewer studies highlight the value of high-resolution topography for imaging faults in urban environments. Using lidar data acquired by the National Center for Airborne Laser Mapping (NCALM) in 2007 for National Science Foundation (NSF)-EarthScope along the principal active faults in northern California, geoscientists at the USGS Earthquake Science Center (Menlo Park, CA) have identified the previously unrecognized surface trace of the Rodgers Creek fault through the center of Santa Rosa, the largest city in the northern San Francisco Bay area (population 175,000). Vertical deformation of the Santa Rosa Creek floodplain expresses a complex pull-apart basin beneath the urban cover that is part of a broader 1-km-wide right-releasing bend in the fault. This information, together with data from recent high-resolution geophysical surveys of Santa Rosa, provides important new capabilities for evaluating the hazard posed by potential large earthquakes on the fault. Results from this study were presented at the 2015 Seismological Society of America Annual Meeting.

Author Name
Suzanne Hecker
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