Measuring vertical displacements from the 2019 Ridgecrest Earthquakes using the post-event lidar point cloud

Guadalupe Bravo, Alba M. Rodriguez Padilla, & Michael E. Oskin

Published September 11, 2022, SCEC Contribution #12337, 2022 SCEC Annual Meeting Poster #153 (PDF)

Measuring vertical displacements from strike-slip earthquakes remains challenging as the vertical motion is small and most geodetic methods are not well suited to measure displacement in the vertical direction in the near field. Here we measure the vertical displacement caused by the M 6.4 and M 7.1 Ridgecrest Earthquakes in 2019 using post-earthquake lidar point cloud. Using the lidR package for R and the lidar point cloud, we created a code to assist in selecting cross-sections along the Ridgecrest faults to measure the vertical displacement in 100-meter spaced increments along the surface rupture. We apply a linear fit to the top and the bottom of the scarps. The vertical separation between the best-fit lines is the vertical displacement accommodated by the fault. Our results highlight that, in flat sections along the rupture, it is possible to resolve vertical displacements as low as 10 cm from the post-earthquake point clouds alone (i.e. without requiring differential lidar). Our preliminary results show variable displacements with a maximum exceeding 2 meters, several scarps exceeding 1 meter, and most of the vertical displacements in the centimeter scale. For the central section of the main shock surface rupture, we from 40 cm mean uplift of the east side of the fault relative to the west side, with meter-scale uplift variations over distances of 1 to 5 km that may be related to variation in horizontal slip at depth.

Citation
Bravo, G., Rodriguez Padilla, A. M., & Oskin, M. E. (2022, 09). Measuring vertical displacements from the 2019 Ridgecrest Earthquakes using the post-event lidar point cloud. Poster Presentation at 2022 SCEC Annual Meeting.

Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)