Small‐scale mapping of the exclusive economic zone using wide‐swath side‐scan sonar

Abstract

The U.S. Geological Survey (USGS) started a program in April 1984 to map the deep‐water (greater than 200 m) areas of the U.S. Exclusive Economic Zone (EEZ) at a reconnaissance scale as a first effort to develop a geologic understanding of the new national offshore territory. This effort was in response to President Reagan's EEZ proclamation in March 1983, which extended U.S. jurisdiction over an area extending 200 nautical miles offshore of the United States and U.S. trust territories. This USGS mapping effort is a cooperative effort with the Institute of Oceanographic Sciences (IOS) of the United Kingdom and uses a unique side‐scan sonar system named GLORIA (Geological Long‐Range Inclined Asdic) developed by IOS. To date, over 3,500,000 km² have been mapped off the west coast, the east coast, the Island of Hawaii, Puerto Rico, and the U.S. Virgin Islands and in the Gulf of Mexico and the Bering Sea. All of these surveys have been highlighted by discoveries of major geologic features that contribute to our understanding of basic geologic principles and processes, composition and character of marine rocks/ sediments, and assessment of nonliving marine resources and geohazards. This program provides “roadmaps”; and “guideposts”; for subsequent, more detailed studies of specific features or areas. A compilation of the processed sonographs, with overlays of bathymetry and geologic interpretations, as well as other types of data (e.g., magnetics and high‐resolution seismic data), is published in an atlas for each survey area at a scale of 1:500,000. To date, the west coast and Gulf of Mexico/Puerto Rico/American Virgin Island data have been published. Results of the Bering Sea and east coast surveys will be published in 1988.