BackgroundThe linear, N-S-trending Escanaba Segment, the southernmost of the Gorda Ridge, lies immediately north of the Mendocino Francture Zone off the coast of northern California. The axial crest of the 130-km-long segment, also known as the Escanaba Trough, is about 3-5 km wide at the northern end and increases to 18 km to the south near the junction with the Mendocino Fracture Zone. The rift valley floor of the slow-spreading Escanaba rift segment lies at about 3200 m depth, bounded by faulted walls about 1500 m high with unusual gold-bearing massive sulfide deposits in sediment hills at the base of the scarps uplifted by volcanic sills or lacoliths. Thick sediment deposits from the continental margin enter the axial trough from the fracture zone and thin to the north. A preliminary uranium-series date of Holocene age was obtained from a basaltic lava flow in the axial valley in the less-sedimented northern part of the Escanaba Segment.
Smithsonian / GVP volcano information
See also: Sentinel hub | Landsat 8