an American geophysicist, is noted for his analyses of earthquake waves and the information they furnish about the physical properties of the structure of the solid Earth. With colleague Charles Richter, Gutenberg published a series of papers in the 1930s on seismic waves that greatly influenced subsequent work. Gutenberg and Richter published Seismicity of the Earth (1941) that provided some of the basic information used by later Earth scientists who developed the theory of plate tectonics. Gutenberg and Richter also collaborated on the development of various magnitude scales using seismic waves of different types so that observers could assign magnitudes to earthquakes that have both shallow and deep foci and occur at various epicentral distances.