GAK_250M_LCC_WGS84.TIF - Gulf of Alaska U.S. EEZ GLORIA sidescan-sonar composite mosaic (LCC, 250 m, WGS84)

The Gulf of Alaska U.S. EEZ GLORIA digital sidescan-sonar mosaic covers about 806,000 square kilometers (sq km) of sea-floor. The mosaic shows the sea-floor morphology from Uminak Pass to Dixon Entrance, from the shelf break seaward to about 400 km. An additional 70-km-wide swath was imaged along the British Columbia margin to follow the trace of the Queen Charlotte Fault south of the Dixon Entrance. Major features visible on the mosaic include continental-margin deformation structures and submarine-channel systems. As in earlier EEZ reconnaissance surveys, the USGS utilized the GLORIA (Geological LOng-Range Inclined Asdic) sidescan-sonar system to complete the geologic mapping. The collected GLORIA data were processed and digitally mosaicked to produce continuous imagery of the sea-floor. A total of 30 digital mosaics with a 50-meter pixel resolution were assembled to complete the Gulf of Alaska overview mosaic.