The 1964 Prince William Sound (Alaska) earthquake, Mw=9.2, ruptured a large area beneath the continental margin of Alaska from Prince William Sound to Kodiak Island. A joint inversion of tsunami waveforms and geodetic data, consisting of vertical displacements and horizontal vectors, gives a detailed slip distribution. Two areas of high slip correspond to seismologically determined areas of high moment release: the Prince William Sound asperity with average slip of 18 m and the Kodiak asperity with average slip of 10 m. The average slip on the fault is 8.6 m and the seismic moment is estimated as 6.3¿1022 N m, or over 75% of the seismic moment determined from long-period surface waves. ¿ American Geophysical Union 1996