Constraining a long history of paleolake and paleoseismicity at Coachella, CA, using deep borehole samples–status: ongoing (2020–2022)

This study provides context for the long-term relationship (up to ~7 ka or more) between the lake loading of the ancient Lake Cahuilla and paleoearthquakes on the southernmost ~100 km of the San Andreas Fault. We drilled and extracted a ~33.5-m long borehole from the NE shorelines of the ancient lake Cahuilla near Coachella, CA. We are currently dating the lake and subaerial stratigraphic units from the borehole using single-grain IRSL and \(^{14}\)C. We recently submitted another proposal to SCEC to extract another borehole from the deep lakebed.

Collaborators: Seulgi Moon (PI), UCLA; Thomas K. Rockwell (Co-I), SDSU; Katherine (Kate) Scharer (Co-I), USGS, Pasadena; Nathan D. Brown (Collaborator), UTA.

Funding Agency: Southern California Earthquake Center (SCEC).

Publications: Saha et al. in prep.


Figure. Coachella (shoreline) core stratigraphic log (CSD-01) showing the alternative subaerial (sandy/silty) and lacustrine (clayey/silty) units. As many as 20 lacustrine units are identified of the ~33.5-m core. Thirteen luminescence samples (brown circles) are dated, and 30 \(^{14}\)C samples (yellow circles) are collected to constrain the lake Cahuilla’s long-term lake filling and desiccation cycles. Published \(^{14}\)C and uncorrected luminesce ages are provided for reference. The upper ~6-m of the log was adapted from Philibosian et al. (2011). Preliminary findings are made available in SCEC interim report.


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