THE SCIENCE LAB

VOLCANIC ROCK

Why the sounds whales make are music to seismologists' ears.

In 2019, Vaclav Kuna, a seismologist was pursuing recordings from dozens Pacific Ocean seismometers, when he heard strange noises : one second chirps, repeating every 30 seconds or so.

The sounds turned out to be songs of whales, and he found these booming cetacean calls where impacting the seafloor.

As they did, some of the energy passed through the ground as seismic waves, which bounced around the buried rocky expanse before being picked up by the ocean-bottom seismometers.

What Dr. Kuna and his colleagues would discover is that fin whale song can be used to peer into the ocean crust. Using this source of seismicity, they found they could see 8,200 feet below the seafloor, through sediments and the underlying volcanic rock.

There would be less need to wait for to wait for the tectonic source of seismic waves, or to send an air-gun-armed ship into the middle of the ocean to create artificial seismicity to visualize the layer-cake nature of the planet's underworlds. [Robin George Andrews]