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Late Holocene Environmental History of UCSB Campus Lagoon

Ryan Owings, Alexander R. Simms, Dillon J. Osleger, & Angel Roman

Submitted September 10, 2023, SCEC Contribution #13148, 2023 SCEC Annual Meeting Poster #070

Large earthquakes, drought, and heightened storm activity associated with El NiƱo Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) have the potential to impact daily life in Southern California and transform the coastal landscape. The stratigraphy and seismic architecture of Campus Lagoon, a flooded river valley incised into a marine isotope stage (MIS) 3 marine terrace near Santa Barbara, California, was examined to better understand the nature and frequency of these events. The valley fill provides a record of late Holocene environmental history for the Santa Barbara region including climate change and potential coseismic uplift within the western Santa Barbara Fold Belt (SBFB). Ten sediment cores and high resolution seismic data collected from UCSB Campus Lagoon between 2013 and 2023 were examined in this study. The oldest sediments sampled were coarse-grained sands dating to 5-4 ka, a period of heightened ENSO. Clayey silts with and without evaporites overlie the sands and were deposited during periods of Holocene aridity between 3.2-0.6 ka. Upper beds of coarse-grained sands suggest a return to stormy conditions and heightened ENSO around 0.6 ka. In addition, seismic surveys collected from Campus Lagoon show two downward shifts in onlap, occurring within the last 4 ka. In the absence of eustatic changes in RSL over this period, they may have been triggered by large magnitude earthquakes that uplifted the lagoon out of an intertidal zone and into an upper intertidal / lower supratidal mudflat.

Key Words
Holocene, Uplift, ENSO, Drought

Owings, R., Simms, A. R., Osleger, D. J., & Roman, A. (2023, 09). Late Holocene Environmental History of UCSB Campus Lagoon. Poster Presentation at 2023 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Geology