Data are available on the surface motions at the epicenter caused by the main shock of the earthquake. These show that the permanent vertical displacements were of the order of 1 m, over an area of about 250 000 sq km. The vertical motions occurred in a period of time short as in comparison to the time for sound propagation over the strained area. The earth's surface thus became a source for an impulsive infrasonic wave in the atmosphere. The radiated‐sound field has been computed from the known surface motions, and the total radiated energy has been estimated. The results depend substantially on the structure of the atmosphere, whose scale height is much less than the linear extent of the sound source.