Using high-resolution multibeam bathymetry to identify seafloor surface rupture along the Palos Verdes fault complex in offshore southern California

Recently acquired high-resolution multibeam bathymetric data reveal several linear traces that are the surficial expressions of seafloor rupture of Ho locene faults on the upper continental slope southeast of the Pales Verdes Peninsula. High-resolution multichannel and boomer seismic-reflection profi les show that these linear ruptures are the surficial expressions of Holoce ne faults with vertical to steep dips. The most prominent fault on the mult ibeam bathymetry is about 10 km to the west of the mapped trace of the Pale s Verdes fault and extends for at least 14 km between the shelf edge and th e base of the continental slope. This fault is informally called the Avalon Knell fault for the nearby geographic feature of that name. Seismic-reflec tion profiles show that the Avalon Knell fault is part of a northwest-trend ing complex of faults and anticlinal uplifts that are evident as scarps and bathymetric highs on the multibeam bathymetry. This fault complex may exte nd onshore and contribute to the missing balance of Quaternary uplift deter mined for the Pales Verdes Hills and not accounted for by vertical uplift a long the onshore Pales Verdes fault. We investigate the extent of the newly located offshore Avalon Knell fault and use this mapped fault length to es timate likely minimum magnitudes for events along this fault.