The way fin whale chants echo from the seafloor could become a useful tool for scientists studying the sediment and rock that make up Earth’s crust, according to new research conducted in the northeast Pacific.
These songs are some of the strongest and most far-reaching vocalizations in the ocean, and with tens of thousands of fin whales scattered around the world, the calls can help expand existing scans or even fill in gaps where it becomes more difficult or even dangerous for marine life. to use the conventional air gun approach.
Ocean floor seismometers can be used to pick up the echoes and fluctuations of the whale sounds, revealing the thickness of the crust beneath, as well as other seismic information useful for scientific research.
(Kuna et al., Science, 2021)
“People have used whale calls in the past to track whales and study whale behavior,” said geophysicist John Nabelek of Oregon State University.
‘We thought we could study the Earth with those calls. If you look closely at the seismometer data after each whale call, there will be a response from Earth. ‘
Nabelek and his colleagues were studying earthquakes near the Blanco Fracture Zone off the coast of Oregon, using a network of 54 seismometers, when they noticed strong signals on the instruments that corresponded 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 last 10 hours or more – traveled as seismic waves through the ground beneath the ocean, before being reflected and refracted by ocean sediment, the basalt layer underneath, and the gabbroic lower crust even lower.
The composition of these bouncing signals could provide estimates of the structure of the ocean crust, the researchers determined: The measurements calculated from whale signals were consistent with other scientific observations of the area.
“This method increases the use of data that is already being collected,” says Nabelek. “It also shows that animal sounds are not only useful for understanding the animals, but also for understanding their environment.”
More research is needed to prepare this method for full deployment – the fin whale songs do not provide as high resolution scan as other seismic survey methods such as the air gun, so they will not completely replace conventional technology.
What they could possibly do is give scientists a more detailed look at the ocean crust and the seismic faults that lead to earthquakes and tsunamis. The researchers suggest that songs from other whales, such as the sperm whale, could also be used.
Ahead, machine learning is an option to automate some of this analysis – and using natural whale calls is certainly a less invasive and simpler method than other approaches to figure out what’s going on beneath the ocean floor.
“The paper serves as a proof of concept that could provide new avenues for using whale call data in research,” said Nabelek. “What we found is that whale calls can serve as an addition to traditional passive seismic survey methods.”
The research is published in Science