Toppling of Trona Pinnacles in the 2019 Ridgecrest Earthquake Sequence and subsequent M5.6 Aftershock of June 2020

Andrea Donnellan, Joaquin Suarez, Domniki Asimaki, Christine A. Goulet, Devin McPhillips, Xiaofeng Meng, Savannah C. Devine, & Gregory A. Lyzenga

In Preparation 2021, SCEC Contribution #11006

Fragile geological features (FGFs) can help us determine the upper-bound limits of ground motions that a region experienced. The Trona Pinnacles monument consists of hundreds of tufa pinnacles and is located about 4 km southwest to the southern end of the 2019 M7.1 Ridgecrest rupture. It provides an unique opportunity to study the damage of FGFs following large ground shaking.
During post-event reconnaissance activities, we identified several freshly damaged spires and took numerous photographs of tufa pinnacles. We later performed a comprehensive internet search for dated images showing pre-event state of spires, which when compared to post-event photographs can allow the identification of more damage. We also made in situ tensile strength measurements at 10 pinnacles and determined the average tufa strength to be ~1.4 MPa. Moreover, we conducted small Unmanned Aircraft System (sUAS) surveys of the Trona Pinnacles and found a spire damaged by a M5.6 aftershock on 2020-06-03. The sUAS data are processed to compute point clouds and digital surface models. By comparing the point clouds, we found additional freshly damaged spires.

Citation
Donnellan, A., Suarez, J., Asimaki, D., Goulet, C. A., McPhillips, D., Meng, X., Devine, S. C., & Lyzenga, G. A. (2021). Toppling of Trona Pinnacles in the 2019 Ridgecrest Earthquake Sequence and subsequent M5.6 Aftershock of June 2020. Seismological Research Letters, (in preparation).