A number of factors must be considered when using particle motion information to determine azimuths to source or azimuths of horizontal geophone axes on or below the ocean floor. These factors include anisotropy, unmatched sensor response, incorrect instrument location, tilted sensors or dipping structure, and poor coupling. Accurate determination of azimuths requires identification and understanding of these factors and their effects on the data. ¿American Geophysical Union 1987