Fin whale songs, one of many loudest animal calls within the ocean, can be utilized to be taught concerning the construction of Earth’s crust.
Václav Kuna on the Institute of Geophysics of the Czech Academy of Sciences in Prague and his colleague John Nábĕlek at Oregon State University considered the concept whereas they had been recording seismic exercise from earthquakes off the coast of Oregon.
“I was processing the data and found that there were some signals recorded which I didn’t recognise,” says Kuna. The thriller was solved when he realised the stations had been recording songs produced by fin whales (Balaenoptera physalus).
Between 2012 and 2013, the researchers deployed 54 ocean-bottom seismometer (OBS) stations to report seismic exercise. Four stations recorded six fin whale songs – patterns of repeated vocalisation – that ranged from 2.5 to just about 5 hours lengthy.
“The calls travel through the water and penetrate into the ground,” says Kuna. “They then bounce off the layers within the oceanic crust and come back to the surface where we record them at OBS stations.”
If you already know the gap between the whale and station, which may be labored out from the frequency of the sound waves, you’ll be able to measure the returning sound waves and decide the make-up and the thickness of Earth’s crust as they refract and mirror by way of totally different layers.
The researchers examined this on the seafloor surrounding the OBS stations and located that the whale songs could present the thickness of the highest sediment layers. Their outcomes matched thickness values beforehand noticed by geologists for layers of the identical crustal age.
Seismic airguns are conventionally utilized in an analogous method to study Earth’s oceanic crust. These create one of many loudest human-made sounds within the ocean by releasing loud blasts of pressurised air, which might misery animals like whales and disrupt their vocalisations. “Airguns produce noise pollution in the ocean. It’s very expensive and it is not environmentally friendly,” says Kuna.
Although whale songs aren’t as efficient as airguns, they could be used to enhance current strategies. Airguns emit a broader vary of frequencies that may mannequin Earth’s oceanic crust at the next decision than the whale songs, however there’s potential to make use of the songs of different whales, reminiscent of sperm whales, which have a broader frequency vary.
Journal reference: Science Advances, DOI: 10.1126/science.abf3962
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