Airborne lidar and electro-optical imagery along surface ruptures of the 2019 Ridgecrest earthquake sequence, southern California

Kenneth W. Hudnut, Benjamin A. Brooks, Katherine M. Scharer, Janis L. Hernandez, Timothy Dawson, Michael E. Oskin, Ramon Arrowsmith, Kelly Blake, Stephan Bork, Matthew Boggs, Craig L. Glennie, Juan Carlos Fernandez-Diaz, Abhinav Singhania, & Darren L. Hauser

Published July 28, 2019, SCEC Contribution #9280, 2019 SCEC Annual Meeting Poster #224

Surface rupture from the Ridgecrest earthquake sequence occurred on July 4 along the 17 km long, northeast-southwest oriented, left-lateral zone of faulting associated with the M 6.4 foreshock. Offset across several strands forming a 165 meter-wide zone, with a total 40-50 cm of left-lateral slip, was documented at the crossing of highway 178 on the evening of July 4. On July 5, the full extent of rupture associated with the M 6.4 was mapped on the ground and observed and photographed from the air. Following the M 7.1 mainshock on July 5, even more extensive northwest-oriented, right-lateral faulting was then mapped along a 50 km long zone of faults as well, which included important sub-parallel splays in several areas. The largest slip was observed in the epicentral area and crossing the dry lakebed of China Lake. A team of as many as several dozen geologists jointly mapped surface fault ruptures for three weeks in July 2019 (e.g., GEER-064, 2019). This initial field rupture mapping helped to precisely guide airborne data acquisition and allowed accurate and efficient flight line planning for high-resolution lidar and aerial photography. Field teams also documented the distribution of offset along the fault ruptures. On that basis, flight line planning was optimized and trade-offs were considered so as to optimally allocate the medium (25 points per square meter, or ppsm) and high resolution (80 ppsm) lidar data collection. The National Center for Airborne Laser Mapping (NCALM) acquired the airborne imagery and a USGS team acquired GPS ground control data. This effort required extensive coordination with Naval Air Weapons Station, China Lake (NAWSCL) as much of the airborne data acquisition occurred within that airspace. In addition to available space-based photogrammetric pre-event digital elevation models (Barnhart, et al., 2019), some aerial pre-event lidar and EO imagery, at least for parts of NAWSCL, may be available from the Navy, with which to compare with post-event imagery; this possibility is still being explored. The data processing and product development remains under way. The datasets will be openly available on opentopography.org following QA/QC and Navy review. We anticipate that these datasets will be instrumental in understanding the near and far field deformation from the Ridgecrest earthquake sequence and form the basis of many future investigations.

Key Words
lidar, Ridgecrest, surface rupture

Citation
Hudnut, K. W., Brooks, B. A., Scharer, K. M., Hernandez, J. L., Dawson, T., Oskin, M. E., Arrowsmith, R., Blake, K., Bork, S., Boggs, M., Glennie, C. L., Fernandez-Diaz, J., Singhania, A., & Hauser, D. L. (2019, 07). Airborne lidar and electro-optical imagery along surface ruptures of the 2019 Ridgecrest earthquake sequence, southern California. Poster Presentation at 2019 SCEC Annual Meeting.

Related Projects & Working Groups
Ridgecrest Earthquakes