Structure of a whale song
To investigate the structure of the sea crust, a wave source is needed. The most common source is an air rifle, which is effective but potentially harmful to ocean life and not easy to use anywhere. Kuna and Nábělek found that songs of fin whales could also be used as a seismic source for determining the crust structure. Fin whale vocalization can be as loud as large ships and occurs at frequencies useful for traveling through the seabed. With these characteristics, fin whale songs can be used to map the density of sea crust, which is an important part of exploring the seabed.
Science, this issue p. 731
Abstract
Fin whale calls are one of the strongest vocalizations of animals that can be observed at great distances in the oceans. We analyze fin whale songs recorded on seismometers on the seabed in the northeast of the Pacific Ocean and show that the song recordings, in addition to the waterborne signal, also contain signals that are reflected and refracted from the crust interface below the stations. With this data we limit the thickness and seismic velocity of the oceanic sediment and basaltic cellar and the P-wave velocity of the gabbroic lower crust below and around the seismic stations on the seabed. The abundant and globally available fin whale calls can be used to supplement seismic studies in situations where conventional air rifle surveys are not available.