High-Resolution Topography along Surface Rupture of the 16 October 1999 Hector Mine, California, Earthquake (M_w 7.1) from Airborne Laser Swath Mapping
In order to document surface rupture associated with the Hector Mine earthquake, in particular, the area of maximum slip and the deformed surface of Lavic Lake playa, we acquired high-resolution data using relatively new topographic-mapping methods. We performed a raster-laser scan of the main surface breaks along the entire rupture zone, as well as along an unruptured portion of the Bullion fault. The image of the ground surface produced by this method is highly detailed, comparable to that obtained when geologists make particularly detailed site maps for geomorphic or paleoseismic studies. In this case, however, for the first time after a surface-rupturing earthquake, the detailed mapping is along the entire fault zone rather than being confined to selected sites. These data are geodetically referenced, using the Global Positioning System, thus enabling more accurate mapping of the rupture traces. In addition, digital photographs taken along the same flight lines can be overlaid onto the precise topographic data, improving terrain visualization. We demonstrate the potential of these techniques for measuring fault-slip vectors.
Additional Information© 2002 Seismological Society of America. Manuscript received 5 March 2002. Without the permission and support of the U.S. Marine Corps Air Ground Combat Center in Twentynine Palms, California, we would not have been able to conduct this study. In particular, we thank Lt. Col. James J. Tabak for his support. Also, W. Karl Gross of the USGS, as liaison with the Marine Corps, provided invaluable assistance with field and aircraft logistics. Bill Krabill provided advice on methods and calibration experiments and has since collected additional data along these flight lines for use in future comparative analyses. We also appreciate the support of Analytical Photogrammetric Services for providing the digital photogrammetric map of the Rheox Hector Mine area, along with the raw data for the gridded elevation data that we used in evaluating the accuracy of this method. Rheox, Inc., allowed us access to their mine to conduct control surveys and carry out other GPS surveys for our calibrations. The SCIGN and its sponsors, the W. M. Keck Foundation, National Aeronautics and Space Administration, National Science Foundation (NSF), and USGS, provided support in the collection of high-sampling-rate GPS data from the nearby SCIGN stations. For these SCIGN data that we used in aircraft positioning, we especially thank John Galetzka, Aris Aspiotes, Keith Stark, and Shannon van Wyk, all at the USGS–SCIGN group in Pasadena. We are also grateful to Jim Dow and others from Aerotec, LLC, for ensuring the success of this project. Reviews by Katherine Kendrick, Greg Anderson, Mark Simons, and Michael Rymer improved this manuscript. This research was funded by the USGS, the Institute of Geophysics and Planetary Physics of the University of California, and the Southern California Earthquake Center (SCEC). SCEC is funded by NSF Cooperative Agreement EAR-8920136 and USGS Cooperative Agreements 14-08-0001-A0899 and 1434-HQ-97AG01718. The SCEC contribution number for this article is 637.
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