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Published July 1, 2020 | public
Journal Article

Airborne Lidar and Electro-Optical Imagery along Surface Ruptures of the 2019 Ridgecrest Earthquake Sequence, Southern California


Surface rupture from the 2019 Ridgecrest earthquake sequence, initially associated with the M_w 6.4 foreshock, occurred on 4 July on a ∼17  km long, northeast–southwest‐oriented, left‐lateral zone of faulting. Following the M_w 7.1 mainshock on 5 July (local time), extensive northwest–southeast‐oriented, right‐lateral faulting was then also mapped along a ∼50  km long zone of faults, including subparallel splays in several areas. The largest slip was observed in the epicentral area and crossing the dry lakebed of China Lake to the southeast. Surface fault rupture mapping by a large team, reported elsewhere, was used to guide the airborne data acquisition reported here. Rapid rupture mapping allowed for accurate and efficient flight line planning for the high‐resolution light detection and ranging (lidar) and aerial photography. Flight line planning trade‐offs were considered to allocate the medium (25 pulses per square meter [ppsm]) and high‐resolution (80 ppsm) lidar data collection polygons. The National Center for Airborne Laser Mapping acquired the airborne imagery with a Titan multispectral lidar system and Digital Modular Aerial Camera (DiMAC) aerial digital camera, and U.S. Geological Survey acquired Global Positioning System ground control data. This effort required extensive coordination with the Navy as much of the airborne data acquisition occurred within their restricted airspace at the China Lake ranges.

Additional Information

© 2020 Seismological Society of America. Manuscript received 28 October 2019; Published online 22 April 2020. The coauthors thank the U.S. Geological Survey and National Science Foundation (NSF) for providing the funding to National Center for Airborne Laser Mapping (NCALM) for this project and the authors especially also thank our pilots Robert Chalender and Greg McDonald and the aircraft vendor. Misty Ellingson and Andria Bullock, with support of Ole Hendon of Naval Air Warfare Center Weapons Division (NAWCWD) provided them with airspace access within the NAWSCL. The authors also benefitted greatly from the generosity of the Inyokern airport manager, Scott Seymour, and his staff who helped to locate parts and facilitate repair of the aircraft in their hangar. Mayor Peggy Breeden and Chief of Police Jed McLaughlin of the City of Ridgecrest opened their arms to our whole team while the authors worked in their city. Margo Allen, Helen Haase, Jeff Mayberry, Rob Gallagher, and Renee Hatcher, the team of Naval Air Weapons Station China Lake and NAWCWD Public Affairs Officers, tirelessly provided operational security review support to our whole team, as did the entire unexploded ordnance team. LT Angela Roush, U.S. Navy, and the R‐2508 Joshua airspace controllers are also greatly thanked, as are California Highway Patrol and National Guard for helicopter support for the field work that allowed our flight line planning. The effective reconnaissance and geodata response resulted from several years of conference calls, e‐mails, meetings, exercises, and planning. It took advanced planning, strategic thought, and coordination with other agencies. The important coordination role of the California Air Coordination Group, led by Derek Kantar of Caltrans, and of the California Earthquake Clearinghouse, co‐led by Anne Rosinski and recently by Cindy Pridmore who co‐led it, along with Heidi Tremayne, Maggie Ortiz‐Millan, and others from Earthquake Engineering Research Institute, during the 2019 Ridgecrest sequence, and of its Overflight committee in particular, cannot be overstated. In addition, U.S. Department of the Interior's Office of Aircraft Services had established memoranda of understanding so that U.S. Geological Survey (USGS) personnel were able to safely conduct multiple aerial reconnaissance and geodata missions. Thanks to the NCALM processing team and the OpenTopography team for making these data available rapidly. Many thanks to the Southern California Earthquake Center (SCEC) headquarters who helped support the Rapid Response Research (RAPID) award from the U.S. NSF. OpenTopography is supported by the U.S. NSF under Award Numbers 1833703, 1833643, and 1833632. Important Global Navigation Satellite Systems (GNSS) data from stations CCCC, P594, and P595 were provided by the Geodetic Facility for the Advancement of GEoscience (GAGE), operated by UNAVCO, Inc., with support from the NSF and the National Aeronautics and Space Administration under NSF Cooperative Agreement EAR‐1724794. The authors also thank the reviewers of this article, Andrew Meigs, James Hollingsworth, Beth Haddon, and Dan Opstal for improving the article. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Data and Resources: The data will all be made available at the following OpenTopography URL: Hudnut, K. W., B. Brooks, K. Scharer, J. L. Hernandez, T. E. Dawson, M. E. Oskin, R. Arrowsmith, C. A. Goulet, K. Blake, M. L. Boggs, S. Bork, C. L. Glennie, J. C. Fernandez‐Diaz, A. Singhania, D. Hauser, S. Sorhus (2020). 2019 Ridgecrest, CA postearthquake light detection and ranging (lidar) collection, National Center for Airborne Laser Mapping (NCALM), distributed by OpenTopography, available at doi: 10.5069/G97W69C0, 10.5069/G9W0942Z. Additional portions of the data set will be released pending additional review. Additional raw files may be accessed from the NCALM long‐term archive, contact ncalm@egr.uh.edu; further information available at http://ncalm.cive.uh.edu/. Capture one image processing software is available at https://www.captureone.com/en/. The B4 lidar data are available in https://u.osu.edu/b4lidar/, https://doi.org/10.5066/F7TQ5ZQ6, and http://opentopo.sdsc.edu/lidarDataset?opentopoID=OTLAS.032018.32611.1. Documentation from NCALM is available at http://ncalm.cive.uh. For further information on Online Positioning User Service (OPUS), see https://www.ngs.noaa.gov/OPUS/ and for more information on the CORS network, see https://www.ngs.noaa.gov/CORS/. GrafNet Overview is available at https://docs.novatel.com/Waypoint/Content/GrafNet/GrafNet_Overview.htm. Current version of TerraScan v.19.019 is available at www.terrasolid.com/products/terrascanpage.php. A detailed discussion on the causes of data artifacts is available at ncalm.berkeley.edu/reports/GEM_Rep_2005_01_002.pdf and a discussion of NCALM procedures is available at ncalm.berkeley.edu/reports/NCALM_WhitePaper_v1.2.pdf. LASer (LAS) format description is available at https://www.loc.gov/preservation/digital/formats/fdd/fdd000418.shtml. American Society for Photogrammetry and Remote Sensing (ASPRS) and LAS formats are available at www.asprs.org/Committee-General/LASer-LAS-File-Format-Exchange-Activities.html. All websites were last accessed in March 2020.

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