Distribution of gas-charged sediment in Norton Sound and Chirikov Basin.

Numerous zone of anomalous acoustic resonses caused by gas in the subsurface sediment layers have been detected on seismic reflection records from Norton Sound and Chirikov Basin. The frequency and distribution of these zones suggest that as much as 7000km2 of the northeastern Bering Sea may be underlain by gas-charged sediment. Much of the gas is of shallow biogenic origin, having been generated in buried peat deposits. Seismic velocity beneath a large gas seep south of Nome decreases in the interval from 250 to 440m below the seafloor, where thermogenic gases of deeper origin are migrating upward along a system of basin margin faults.-from Authors