The Long Beach-Seal Beach Thrust Belt: A Revised 3D Seismic Structural Model, Western LA Basin, California

Abstract Tectonic models for the Long Beach – Seal Beach area have historically been inferred as being dominated by a narrow belt of northwest-southeast, right lateral strike slip faults, generally referred to as the Newport-Inglewood Fault Zone (NIFZ). Analysis of a proprietary 28 sq mile (72.5 sq km) 3D dataset centered over the Seal Beach Anticline reveals that the study area is undergoing more deformation across a far wider area than previously recognized, the Seal Beach Anticline (SBA) is a doubly-terminated anticline, carried by a previously unrecognized thrust fault which surfaces 1.5 mi east of the NIFZ, the SBA structural axis is not vertical and disappears abruptly below approximately 5,500 ft (1676 m), faults previously identified as the NIFZ represent a subset of complex antithetic faults; and blind thrusts extend northeastward nearly six miles into the Los Angeles Basin, accompanied by recent micro-earthquake events. This data provides a basis for a revised structural model in the Long Beach area.