Poster #044, Ground Motions

Database of Fragile Geologic Features from the Trona Pinnacles National Monument

Christine A. Goulet, Xiaofeng Meng, & Savannah C. Devine
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Poster Presentation

2021 SCEC Annual Meeting, Poster #044, SCEC Contribution #11542 VIEW PDF
The definition of ground motion upper limits is a key knowledge gap for the design of critical infrastructure such as power plants or dams. Fragile geologic features (FGFs) that are damaged or toppled by strong earthquake shaking can provide insight into the quantification of such extreme ground motions with low recurrence intervals. The presence of intact FGFs is evidence that no strong ground accelerations have occurred for as long as the FGF has been in its state, which can be several thousand years under desertic climates. The observation of damaged/undamaged FGFs following earthquakes is critical in calibrating and validating ground motion assessment methodologies developed from lab exp...eriments and numerical modeling.

The Trona Pinnacles National Monument, which contains several tufa spires, is located within 5 km of the mapped 2019 M7.1 Ridgecrest earthquake fault trace. Some of the tufa spires sustained variable levels of damage from the Ridgecrest earthquake sequence. Several days after the mainshock, a SCEC team visited the Monument and took photographs of the spires, both damaged and undamaged. A team from the Jet Propulsion Laboratory (JPL) also imaged several of the features from small unmanned aerial systems (sUASs). The Pinnacles have also been heavily photographed by both scientists and tourists over the years, and these photographs can be used to document the state of the spires prior to the Ridgecrest earthquake sequence. We have been developing a database that captures the pre- and post-event conditions of the tufa spires. The database will be made available to researchers working on ground motion estimation methodologies to constrain the ground motion level from nearby earthquakes in the future.

We first collect EXIF information from picture files and populate Google Earth maps with oriented photographs for easy viewing. We then identify and assign numbered IDs to all photographed FGFs taken from the post Ridgecrest reconnaissance activities. This is archived by an interpretation of the photographs themselves, and supported by the Google Earth maps and the 3D images provided by the JPL sUAS team. We then systematically search and catalog pre-event photographs of the FGFs from online resources. Finally, an interactive webpage is created for users to query, view, and print all the information and images associated with each spire. In this presentation, we introduce the prototype webpage and its capabilities.