Onshore and offshore data are providinga complete picture of gravity at the ocean-continent transition of South America's western continental margin. Researchers are finding that the Andean gravity field seems to be linked to many processes that contribute to the tectonic framework of the Nazca subduction zone.
The data were collected on land, in the ocean, and from space. Since 1982, some 6,000 new gravity observations have been made on land in an Andean geotraverse covering northern Chile, southwestern Bolivia and northwestern Argentina [Götze et al., 1994, 1995]. Offshore gravity data were collected in the summer of 1995 from the R/V Sonne between latitude 20°S and 24°S. Marine gravity data from satellite altimetry (poster) by D. T. Sandwell and W. H. F. Smith are available from the Geological Data Center, Scripps Institution of Oceanography, La Jolla, CA 92093, (digital file, Version 7.2) anonymous ftp to baltica.ucsd.edu). In 1995, these data were added to the database to fill in marine areas that had not been surveyed by shipborne gravity.