For more than 20 years, gravity surveys have been conducted in the vicinity of Prince William Sound, the epicentral region of the great Alaska earthquake of March 27, 1964. Some of the major regional gravity anomalies were outlined by Thiel, Ostenso, Bonini (1960), and additional anomalies were defined by pre- and post-earthquake gravity studies reported by Barnes and Allen (1965) and Case, Barnes, Plafker, and Robbins (1966). Another gravity anomaly map was prepared by personnel of the U.S. Coast and Geodetic Survey (now the National Oceanic and Atmospheric Administration) (Wood, 1966, p. 131; Rice, 1969, p. 5-20). Anomalies shown by Rice (1969) are broadly similar to those shown by Case, Barnes, Plafker, and Robbins (1966); Rice's interpretations concerned mainly gravity changed related to the earthquake, and the data were not interpreted in terms of regional geology. New gravity stations were established in 1976 as part of the mineral resource appraisal of the Seward and Blying Sound quadrangles. This report incorporates the new data obtained in 1976, reinterprets some anomalies previously discussed by Case, Barnes, Plafker, and Robbins (1966), and interprets other anomalies not previously discussed. Descriptions of the major rock units and structural features are found in the companion report by Tysdal and Case (in press). An interpretation of the aeromagnetic map of the region has been prepared by Case, Tysdal, Hillhouse, and Gromme (1979).
