Group , Poster #066, Earthquake Geology

Kinematic evolution of the Palos Verdes restraining bend and 3-D architecture of the fault, Southern California

Franklin D. Wolfe, John H. Shaw, & Andreas Plesch
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Poster Presentation

2021 SCEC Annual Meeting, Poster #066, SCEC Contribution #11361 VIEW PDF
The Palos Verdes Fault Zone (PVFZ) extends across the southwestern Los Angeles Basin and Inner Continental Borderland, California, and is considered capable of generating large, damaging earthquakes with short recurrence intervals. The 110-km-long fault zone is composed of vertical and moderately dipping segments that accommodate oblique, right-lateral reverse displacement. Onshore, the PVFZ undergoes a counterclockwise rotation, producing a major restraining bend that generates the Palos Verdes Peninsula. Here, we use well and seismic reflection data to develop kinematic models that show how folding of the PVFZ by the Wilmington blind-thrust formed the restraining bend. We use these insight...s to develop a new, comprehensive 3-D model of the PVFZ that incorporates results from prior studies in the San Pedro and Santa Monica Bays. North of the peninsula in Santa Monica Bay, debate persists over the extent, geometry, and activity of the PVFZ. Here, we analyze a dense grid of high-resolution seismic reflection data and present new mapping of the Santa Monica Bay segment of the PVFZ, including multiple active splays (e.g., Redondo Canyon Fault Zone) that occur within a very broad damage zone at the northern termination of the fault system. Together, these insights contribute to a new comprehensive model for the geologic evolution and 3-D geometry of the PVFZ that has important implications for the seismic hazard it poses to the broader Los Angeles metropolitan region.
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