Mapping ocean floors is crucial for recognizing seismic activity and evaluating carbon storage capacity. To perform this activity, scientists use large air guns that send loud sounds down to the surface and back up again.
This process however is very expensive and disrupts marine mammals' natural habitat. Now, scientists have figured out a way to use whale sounds for the same purpose.
Fin whales are 60 to 85-foot-long (20 to 25 mt) animals whose cries can be heard up to 600 miles (1,000 kilometers) away. Researchers are now discovering that these sounds can be used to map the ocean floor down to 1.6 miles (2.5 kilometers).
“It’s actually quite cool to have another source of information,” told Scientific American study co-author Václav Kuna, a seismologist at the Institute of Geophysics of the Czech Academy of Sciences.
Kuna explained that he noticed that the whale sound signals showed up only on the seafloor instruments’ seismometers, indicating that the signals were not coming directly from the whales, but were instead echoes bouncing back from the ground.
Kuna then had to find the whales’ locations in order to use their cries for imaging. He achieved this by comparing the whales' two sets of waves: one that headed to the ocean floor and another that bounced between the ocean floor and the surface.
The technique is not foolproof. Kuna explained that whale cries are limited in frequency resulting in subsurface images that are not as clear as those made with air guns. Still, their added value to the field of ocean mapping is undeniable.
“If we use the whale songs at least as a complement to other sources of signals, they are free and they are always there,” Kuna told Scientific American. “It’s a win-win.” The next time you hear a whale song, remember it's more than a beautiful cry.
The study was published in the journal Science.