When Katrina hit California

Beamforming of seismic noise recorded on 150 Southern California stations was used to identify body and surface waves generated by Katrina. Surface wave microseisms are commonly associated with oceanic storms; there are no previous comprehensive body wave observations. The temporal evolution of the surface and body waves was different, indicating a different source mechanism for the two wave types. The body-waves originated in shallow water east of New Orleans and propagated deep inside the Earth. The surface waves have source location that varies with frequency with the lowest frequency surface waves originating west of the hurricane track and the higher frequency ones to the east. The seismic observations are consistent with ocean wave hindcasts and provide clear association of microseism noise with storm activity.