Analysis of Gorda Escarpment Geomorphology, Mendocino Fracture Zone

Multibeam survey data from the R/V Atlantis 2014 cruise-AT26-21 were used to examine the east-west trending Gorda Escarpment of the Mendocino Fracture Zone, west of the Gorda Spreading Ridge. This area lies on the Pacific Plate and includes several seamounts and geologic structures. Using Caris HIPS and SIPS 9.0 software, features along the fracture zone were characterized to determine offsets from plate movement along with analysis of associated seamount geomorphology. The extent of movement along the fault line was determined by comparing offsets of corresponding narrow ridges to its north and south. The northern complex ridges have warped, with a curvature along the fracture zone towards the east, indicating that this portion of the Pacific Plate north of the fracture is migrating westward at a faster rate than the area south of the fracture. The result is an offset along the fracture which ranges from 5.0 to 7.0 km. The seamount chain to the south of and parallel to the fracture zone is approximately 124 km long with the largest seamount to the west. Lava lobes and terraces are significantly more abundant on the seamounts’ south flanks suggesting asymmetry in eruptive sequences. Information gathered from the study area is beneficial to understanding fracture zones of the Mendocino Triple Junction and may contribute to studies of tectonic and seismic activity for the nearby Northern California coast.