Targeted High-Resolution Structure from Motion Observations over the Mw 6.4 and 7.1 Ruptures of the Ridgecrest Earthquake Sequence

Andrea Donnellan, Gregory Lyzenga, Adnan Ansar, Christine Goulet, Jun Wang, & Marlon Pierce

Published March 18, 2020, SCEC Contribution #10137

We carried out six targeted structure from motion surveys using small uninhabited aerial
systems over the Mw 6.4 and 7.1 ruptures of the Ridgecrest earthquake sequence in the
first three months after the events. The surveys cover approximately 500 × 500 m areas
just south of Highway 178 with an average ground sample distance of 1.5 cm. The first
survey took place five days after the Mw 6.4 foreshock on 9 July 2019. The final survey
took place on 27 September 2019. The time between surveys increased over time, with
the first five surveys taking place in the first month after the earthquake. Comparison of
imagery from before and after the Mw 7.1 earthquake shows variation in slip on the main
rupture and a small amount of distributed slip across the scene. Cracks can be observed
and mapped in the high-resolution imagery, which show en echelon cracking, fault
splays, and a northeast-striking conjugate fault at the Mw 7.1 rupture south of
Highway 178 and near the dirt road. Initial postseismic results show little fault afterslip,
but possible subsidence in the first 7–10 days after the earthquake, followed by uplift.

Citation
Donnellan, A., Lyzenga, G., Ansar, A., Goulet, C., Wang, J., & Pierce, M. (2020). Targeted High-Resolution Structure from Motion Observations over the Mw 6.4 and 7.1 Ruptures of the Ridgecrest Earthquake Sequence. Seismological Research Letters, 91(4), 2087-2095. doi: 10.1785/0220190274.