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Liquefaction or Liquefiction? Anthropogenic Regulation and the Influence of Evaporite Dissolution on Ground Failure in the 2019 Ridgecrest Earthquake Sequence

Description: 

Optical remote sensing observations of the 2019 Ridgecrest, California, earthquake sequence revealed a significant amount of surface ejecta in the nearby Searles Lake, including one area where the surface ejecta was arranged in a repeating hexagonal “honeycomb” pattern. This pattern is collocated with injection wells from a solution mining operation, suggesting anthropogenic activities influenced the spatial distribution of surface ejecta. Geologic cores throughout the lakebed reveal massive evaporite units interfingered with clay and silt units, and a notable lack of traditionally liquefiable sand-dominated units. Soil behavior types acquired from cone penetration tests (CPT) on the periphery of the lakebed, where more sand-dominated united are expected, estimate less than 3% of traditionally liquefiable contractive sand layers. Satellite-based Interferometric Synthetic Aperture Radar (InSAR) data show highly localized subsidence signals in the same hexagonal pattern in the four years leading up to the earthquake sequence. The lithology, CPT-derived soil behavior, and spatial distribution of long-term subsidence indicate that surface ejecta in Searles Lake is not likely related to liquefaction. Instead, we propose a process, similar to liquefaction, that would also result in the observed surface ejecta: (1) mining-related dissolution of evaporites increases the void/cavity space that is filled with fluid, (2) ground shaking causes void/cavity collapse (i.e., a volume reduction), (3) the collapse increases the fluid pressure, and (4) the increased pressure results in sediment-laden fluid to flow to the surface. This study is an excellent example of how remotely sensed optical and InSAR data can assist in rapid identification and evaluation of spatially distributed ground failure features and their effects across a variety of geologic deposits and terrains.

Session: Coseismic Ground Failure: Advances in Modeling, Impacts and Communication [Poster]

Type: Poster

Date: 4/20/2023

Presentation Time: 08:00 AM (local time)

Presenting Author: Paula M. Burgi

Student Presenter: No

Invited Presentation: 

Authors