Recency of Faulting and Subsurface Architecture of the San Diego Bay Pull-Apart Basin, California, USA

In Southern California, plate boundary motion between the North American and Pacific plates is distributed across several sub-parallel fault systems. The offshore faults of California Continental Borderland (CCB) are thought to accommodate ∼10–15% total motion, but exact distribution slip mechanics partitioning remain uncertain. Newport-Inglewood-Rose Canyon easternmost within CCB whose southern segment splays out into a complex network beneath San Diego Bay. A pull-apart basin model Rose Descanso has been used explain prominent orientations subsidence Bay; however, this does not account for in portion bay or faulting east bay. To investigate characteristics stratigraphic architecture Bay, we combined suite reprocessed legacy airgun multi-channel seismic profiles high-resolution Chirp data, with age lithology controls from geotechnical boreholes shallow sub-surface vibracores. This dataset create gridded horizon surfaces, maps, perform kinematic analysis. structure Bay dominated by down-to-the-east on normal that can be separated two distinct groups. strikes these groups explained double our conceptual model, western controlled right-step faults, which matches both observations predictions laboratory models. eastern appears an inferred step-over Miguel-Vallecitos displays strike orientations, analysis indicates should have significant component strike-slip detectable data. potential Canyon-San connection would effectively cut stepover distance half important implications hazard Diego-Tijuana metropolitan area (population ∼3 million people).