The new way in which the songs of fin whales resonate from the sea floor could become a useful tool for scientists studying the sediment and rock that make up the earth’s crust, according to new research in the Northeast Pacific.
These songs are some of the strongest and most far-reaching voices in the ocean, and with tens of thousands of fin whales scattered around the world, the calls can add to existing scans or even fill in gaps where it is more difficult or even more. dangerous to marine life using the conventional air rifle approach.
Seismometers on the ocean floor can be used to pick up the echoes and fluctuations of fin whales, which reveal the thickness of the crust at the bottom, as well as other seismic information useful for scientific research.
(Kuna et al., Science, 2021)
“People in the past have used whale calls to detect whales and study whale behavior,” said Oregon State University geophysicist John Nabelek.
“We thought we could study the earth using those calls. After every whale call, if you look at the seismometer data closely, there is a response from the earth.”
Nabelek and his colleagues studied earthquakes near the Blanco Fracture Zone off the coast of Oregon, using a network of 54 seismometers, when they saw strong signals on the instruments corresponding to the presence of whales in the area.
Further analysis of six calls revealed that the underwater songs – which can be as loud as large ships, and which can last 10 hours or longer – traveled through the ground under the ocean as seismic waves, before reflecting and breaking. by the ocean sediment the basalt layer below, and the gabbroic lower crust even lower down.
The composition of these reflective signals can inform the estimates of the structure of the sea crust, the researchers determined: the measurements calculated from whale signals are consistent with other scientific observations in the area.
“This method expands the use of data already collected,” says Nabelek. “It also shows that vocalizations of animals are not only useful for understanding animals, but also for understanding their environment.”
More research will be needed to prepare this method for full deployment – the fin whale songs do not offer as high a resolution scan as other seismic methods such as the air rifle, so they will not completely replace conventional technology.
What they can do is give scientists a more detailed look at sea crust and the seismic faults that lead to earthquakes and tsunamis. The researchers suggest that songs from other whales, such as the potfish, could also be used.
Going further, machine learning is one option to automate some of this analysis – and using natural whale calls is certainly a less intrusive and simpler method than other approaches when it comes to figuring out what’s going on under the seabed.
“The paper serves as proof of concept that could offer new possibilities for the use of data from whale calls in research,” says Nabelek. “What we have discovered is that whale calls can serve as a complement to traditional passive seismic research methods.”
The research was published in Science.