The local magnitude scale was developed on the basis of shallow (~ deep), moderate-sized earthquakes at a distance of approximately , conditions where the surface waves are predominant. At greater depths, distances, or magnitudes the surface waves are greatly reduced, and the local magnitude scale underestimates the magnitude, a problem called "saturation". Additional scales were developed – a surface-wave magnitude scale () by Beno Gutenberg in 1945, a body-wave magnitude scale () by Gutenberg and Richter in 1956, and a number of variants – to overcome the deficiencies of the scale, but all are subject to saturation. A particular problem was that the scale (which in the 1970s was the preferred magnitude scale) saturates around and therefore underestimates the energy release of "great" earthquakes such as the 1960 Chilean and 1964 Alaskan earthquakes. These had magnitudes of 8.5 and 8.4 respectively but were notably more powerful than other M 8 earthquakes; their moment magnitudes were closer to 9.6 and 9.3.