Their songs are loud enough to penetrate Earth’s crust and reveal deep structures. Fin whale songs can be up to 189 decibels and each song last up to 5 hours. A new study finds that their calls are strong enough to penetrate into rock beneath the seafloor and the echoes of those songs bouncing off the rocks can help reveal the structure of the Earth’s crust.

These instruments detect waves that travel through the ground, such as those caused by earthquakes. It turns out that they can also pick up songs from a passing whale. When sound waves traveling through the water meet the ground, some of the waves’ energy converts into a seismic wave and those seismic waves can help scientists estimate the thickness of the layers and the composition of the rocks the echo passed through.