Premium
The Palos Verdes Fault offshore Southern California: Late Pleistocene to present tectonic geomorphology, seascape evolution, and slip rate estimate based on AUV and ROV surveys
Author(s) -
Brothers Daniel S.,
Conrad James E.,
Maier Katherine L.,
Paull Charles K.,
McGann Mary,
Caress David W.
Publication year - 2015
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1002/2015jb011938
Subject(s) - geology , fault scarp , seafloor spreading , fault (geology) , escarpment , sedimentary rock , geomorphology , paleontology , pleistocene , holocene , bathymetry , seismology , oceanography
The Palos Verdes Fault (PVF) is one of few active faults in Southern California that crosses the shoreline and can be studied using both terrestrial and subaqueous methodologies. To characterize the near‐seafloor fault morphology, tectonic influences on continental slope sedimentary processes and late Pleistocene to present slip rate, a grid of high‐resolution multibeam bathymetric data, and chirp subbottom profiles were acquired with an autonomous underwater vehicle (AUV) along the main trace of PVF in water depths between 250 and 600 m. Radiocarbon dates were obtained from vibracores collected using a remotely operated vehicle (ROV) and ship‐based gravity cores. The PVF is expressed as a well‐defined seafloor lineation marked by subtle along‐strike bends. Right‐stepping transtensional bends exert first‐order control on sediment flow dynamics and the spatial distribution of Holocene depocenters; deformed strata within a small pull‐apart basin record punctuated growth faulting associated with at least three Holocene surface ruptures. An upper (shallower) landslide scarp, a buried sedimentary mound, and a deeper scarp have been right‐laterally offset across the PVF by 55 ± 5, 52 ± 4 , and 39 ± 8 m, respectively. The ages of the upper scarp and buried mound are approximately 31 ka; the age of the deeper scarp is bracketed to 17–24 ka. These three piercing points bracket the late Pleistocene to present slip rate to 1.3–2.8 mm/yr and provide a best estimate of 1.6–1.9 mm/yr. The deformation observed along the PVF is characteristic of strike‐slip faulting and accounts for 20–30% of the total right‐lateral slip budget accommodated offshore Southern California.