Fault and depositional architecture of the Catalina Basin, southern California Inner Continental Borderland: implications for hazards and basin evolution

Maureen L. Walton, Daniel S. Brothers, James E. Conrad, Katherine L. Maier, Emily C. Roland, & Jared W. Kluesner

Submitted August 15, 2017, SCEC Contribution #7827, 2017 SCEC Annual Meeting Poster #221 (PDF)

The Catalina Basin, located within the southern California Inner Continental Borderland (ICB), is traversed by two active offshore fault systems within the larger San Andreas distributed plate boundary system: the San Clemente Fault (along with a prominent splay, the Kimki Fault) and the Catalina Fault. The Catalina Basin has been largely ignored in offshore geophysical surveys despite evidence that these faults, particularly the San Clemente Fault, could be accommodating as much as 4-6 mm/yr of the total ~8 mm/yr right-lateral slip taken up within the ICB between San Clemente Island and the coast. Previous work has not accurately documented active fault locations, geometries, histories, or strain partitioning across the Catalina Basin.

Here, we provide new constraints on the San Clemente and Catalina fault systems using high-resolution geophysical data collected in 2014-2016. Geophysical datasets including multibeam bathymetry, multi-channel seismic, and CHIRP sub-bottom profiles provide high-resolution imaging of the fault systems and depositional architecture in the Catalina Basin. Our results include the locations of active fault strands, updated fault geometries, seismic-reflection mapping of basin fill sequences, and constraints on the timing of deformation and basin evolution since the late Miocene. Inherited crustal fabrics, as indicated by potential fields data, have likely influenced the geometry of the main trace of the San Clemente Fault; in the northern Catalina Basin, for example, the fault forms a releasing bend where it diverts around a magnetic asperity interpreted to be a relatively hard crustal block. Elsewhere, Quaternary faults cut across Miocene-generated tectonic geomorphology, indicating that inherited faults may have less bearing on modern fault geometry than crustal fabric. Finally, we quantify cumulative seismic moment release along fault segments in the Catalina Basin and highlight an area along the San Clemente Fault that may be seismically locked and poised to rupture. The San Clemente Fault may be accruing as much as ~3.5 mm/yr of right-lateral strain, whereas the Catalina and Kimki faults are likely accommodating much smaller amounts (<1 mm/yr) of transpressional slip, and could have formed in response to the forced releasing bend in the San Clemente Fault.

Key Words
borderland, Catalina, San Clemente, fault, offshore, marine, seismic, hazard, slip rate

Walton, M. L., Brothers, D. S., Conrad, J. E., Maier, K. L., Roland, E. C., & Kluesner, J. W. (2017, 08). Fault and depositional architecture of the Catalina Basin, southern California Inner Continental Borderland: implications for hazards and basin evolution. Poster Presentation at 2017 SCEC Annual Meeting.

Related Projects & Working Groups
Stress and Deformation Over Time (SDOT)