SCEC Award Number 20119 View PDF
Proposal Category Collaborative Proposal (Data Gathering and Products)
Proposal Title SCEC-NASA Collaborative Proposal: Database Development for the Trona Pinnacles Fragile Geologic Features
Name Organization
Christine Goulet University of Southern California Andrea Donnellan National Aeronautics and Space Administration Gregory Lyzenga Harvey Mudd College Xiaofeng Meng University of Southern California Devin McPhillips United States Geological Survey
Other Participants
SCEC Priorities 4b, 5b, 3e SCEC Groups Geology, EEII, GM
Report Due Date 03/15/2021 Date Report Submitted 05/07/2021
Project Abstract
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.
All the images and data collected are aggregated into a database. Within the database, each spire is given an unique ID. Then, the IDs of all spires appearing in each image are identified and linked to the table of photographs. Once the database is finalized, it will be made available to the entire SCEC community to calibrate and validate FGFs ground motion assessment methodologies developed from lab experiments and numerical modeling.
Intellectual Merit The determination of the upper limits of ground motions is a key knowledge gap for the design of critical infrastructure such as nuclear repositories, power plants or even dams. Our work of surveys, field measurements and documentations of damaged Fragile Geological Features (FGFs) following Ridgecrest earthquake sequence is critical in calibrating and validating FGF ground motion assessment methodologies developed from lab experiments and numerical modeling. The work is in direct alignment with SCEC’s mission on “gathering information from seismic and geodetic sensors, geologic field observations, and laboratory experiments”.
Broader Impacts Our work could help determine the upper-bound limits of ground motions that Trona experienced and validate numerical ground motion modeling. The database will be used by the SCEC community as the reference when looking for damaged FGFs following future earthquakes.
SCEC SOURCES intern Savannah Devine is a main contributor in this project and performed several critical tasks for the inventory of the pinnacles and the database development. We devised tasks to help her develop a skill set in various areas including computer programming, planning and management of research tasks, and communications.
Exemplary Figure Figure 2. Snapshots of point clouds and digital surface models from the small Unmanned Aircraft System surveys. Left: Flight grid (blue and green dots) overlayed on the digital surface model of Trona Pinnacles. Middle: The digital surface model of Trona Pinnacles. Top right: Circular flight paths around selected spires. Bottom right: Digital surface model of selected spires.