We know very little about the ocean floor, but now scientists are getting help to learn something about the most unexpected aspect – the fin whale. The song of the fin whale is one of the loudest sounds made by animals, and can be heard at great sea distances. These sound waves also enter the Earth and how scientists can use it explore the density of ocean sediments.
The fin whale (Balaenoptera physalus) is slightly less known than the long (and much heavier) blue whale and show-off humpback. Yet these are amazing creatures of amazing speed. Like other great whales, males also sing songs in complexes to attract music, partly less than we hear.
Rising noisy oceans thought to be interfering with the recovery of fin whales from widespread hunting. Among the interventions in ocean life were seismic air gun surveys: Dr. Václav Kuna of Oregon State University and Dr. John Nábëlek wondering if it was possible to use the fin whale’s own words to investigate the sea floor. Need to make more annoying noises.
In science, Kuna and Nábelek have reported on their first attempt at this. In 2012, 54 low-seismometer stations used to monitor the Blanco Fault off the coast of Oregon. In addition to the underwater tremors, these stations have recorded many songs by nearby fin whales, sometimes lasting up to 10 hours. The songs recorded at these three stations, Kuna and Nábelek, compare the sound waves that enter the station directly to the station and turn them into earthquake waves. Earthquake waves cross the boundary between sediment and basalt and basalt and lower crust before reaching the stations. The delay in the arrival of the reflected waves reflects the impedance of each level.
Helpfully, the whales were at uninterrupted speeds during their song, which allowed the researchers to work some 20 kilometers (12.4 miles) directly above the quake. Putting all these data together, the authors calculated a sedimentary thickness of 380 to 650 meters (1,250-2,150 feet) for the sea floor around the stations, falling 1.8 kilometers (1 mile) above the basaltic rock. The sediment estimate is thinner than conventional measurements taken further north, but the authors think this is not surprising due to the greater distance from the original sediment source.
The authors believe that higher pitch sperm whale songs can be used to measure higher resolution. “Our research proves that animal voices are effective not only for studying animals themselves but also for investigating the environment in which they live.” The range of fin whales is so wide that their songs are widely available for research purposes. When Finn Whale’s songs recorded so loudly (beyond the amount of a rocket launch) in the first half, they thought it to be geographical events or some Russian activity in the Cold War.