“For some of us it was just, ‘ugh, those dung whales are in my data,” said Dr. Caplan-Auerbach. Humpback whales have historically paused their research on Lo’ihi Seamount, an underwater Hawaiian volcano. “We had Tons and tons of whale singing, and for me it was just total noise in my data. “
But as this new study shows, this noise can be used to study the interior of the planet. “And that’s great,” she said.
“It will never replace air rifles,” said Dr. Kuna. The fin whale seismic waves are somewhat weak, which means that their subsurface mapping is of relatively low resolution. “But it’s an addition. And it’s free. “
Although seismologists are careful to avoid marine life, a recent report detailed how noisy the oceans have become in recent years as a result of human activity. Finding more ways to take advantage of fin whale seismology may mean adding less to the cacophony. “It’s win-win,” said Dr. Kuna.
For this study, the researchers had to determine the location of the fin whales, similar to finding the epicenter of an earthquake. They observed the arrival times of both the sound waves of the chirp that went straight to the seismometer and the sound waves that ricocheted between the sea surface and the sea floor. The time difference showed the distance of the whale. With some reasonable assumptions about the typical swimming depth of the fin whale, they were able to track their journeys through the ocean.
This article may be about the seismological benefits of fin whales, but this method could prove useful to marine ecologists, said Dr. Wilcock. In recent years, land seismometers have attempted to track elephants and estimate their populations. The same principle could apply to fin whales, animals caused by climate change, habitat loss, and the dire legacy of commercial whaling. And like those seismometers that eavesdrop on elephants, machine learning can one day listen to typical fin whale songs and autonomously recognize different pods of fin whales or individuals within those groups.
“We can use the tools of biology to study seismology,” said Dr. Caplan-Auerbach. “And we can use the tools of seismology to study biology.”