Data from the Earth Resources Technology Satellite (ERTS) are being utilized for cartographic, geologic, and other earth-science purposes by most nations of the world. The Earth Resources Observation Systems (EROS) Data Center in Sioux Falls, South Dakota, is supplying data directly to 96 nations, many from the Circum-Pacific region. The cartographic qualities of data from ERTS, especially that from MSS (multispectral scanner), have exceeded prelaunch expectations. MSS data have been used to produce photo maps of parts of the United States that have root mean square positional errors of less than 150 m. Structural geologic information has been obtained from Nimbus and later ERTS data have led to revision of the metallogenic map of Alaska and are providing focus on potential locations of metallic ores in other areas of the western hemisphere. Observations of the distributions, shapes, and orientations of lakes, stream valleys, and other water features as seen in the synoptic images from ERTS provide new insight into the presence of deep-seated structures that may have metals or petroleum significance. Tectolinear interpretations of ERTS-1 data, in conjunction with seismic epicentral data from other sources, may provide a new approach in defining hazardous areas for future development. Recent work involving special processing of ERTS images of parts of Nevada have led to a capability to detect and map areas of surface alteration--a well-known guide to ore deposits. The Data Collection System (DCS) experiment aboard ERTS is being used to receive and retransmit information from a variety of in-situ sensors, including tiltmeters and seismic event counters on 16 volcanoes in North and Central America. Precursor earthquakes of 80 events per day recently signalled the eruption of Volcan Fuego in Guatemala. End_of_Article - Last_Page 1436------------