Floods, storms, and the identification of wave-dominated deltas: Insights from ground-penetrating radar profiles of the Oxnard Plain

Julie M. Zurbuchen, & Alexander R. Simms

Published August 15, 2016, SCEC Contribution #6993, 2016 SCEC Annual Meeting Poster #106

Tsunamis often occur in tectonically active areas, where they pose a significant risk to property and life along low-elevation coastal regions. In California, tsunami studies have traditionally focused on the Cascadia Subduction Zone in the north, however historical records and recent models, including those for the Ventura-Avenue Anticline-Pitas Point Thrust, have shown that tsunamis may pose a significant threat to the southern California coastline as well. A ground-penetrating radar (GPR) survey was collected along the shoreline of the Oxnard Plain to look for evidence of erosion caused by past tsunamis. 100 MHz, 200 MHz, and 500 MHz GPR profiles were collected at five state beaches in the area penetrating depths of up to 6, 3, and 2 meters, respectively. Although several erosional surfaces were identified, no evidence for tsunami erosion was found within the GPR profiles. However, to date, the length of our record is unknown. The identified erosional surfaces are interpreted as storm erosion due to their frequency and occurrence in parts of the coastal plain that formed over historical periods. The prevalence of landward-dipping reflections near the Santa Clara River delta may provide a stratigraphic signature of events associated with large sediment output from the river (i.e large inland storms) and a means of distinguishing wave-dominated deltas from prograding clastic shorelines in the ancient rock record.

Key Words
Tsunami, Ventura, earthquake hazards

Citation
Zurbuchen, J. M., & Simms, A. R. (2016, 08). Floods, storms, and the identification of wave-dominated deltas: Insights from ground-penetrating radar profiles of the Oxnard Plain. Poster Presentation at 2016 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Geology