Fin whale songs can reveal hidden options of the ocean flooring

The fin whale’s name is among the many loudest within the ocean: It could possibly even penetrate into Earth’s crust, a brand new research finds. Echoes in whale songs recorded by seismic devices on the ocean flooring reveal that the sound waves cross by means of layers of sediment and underlying rock. These songs may help probe the construction of the crust when extra standard survey strategies aren’t obtainable, researchers report within the Feb. 12 Science.

Six songs, all from a single whale that sang because it swam, have been analyzed by seismologists Václav Kuna of the Czech Academy of Sciences in Prague and John Nábělek of Oregon State College in Corvallis. They recorded the songs, lasting from 2.5 to 4.9 hours, in 2012 and 2013 with a community of 54 ocean-bottom seismometers within the northeast Pacific Ocean.

The songs of fin whales (Balaenoptera physalus) might be as much as 189 decibels, as noisy as a big ship. Seismic devices detect the sound waves of the tune, similar to they decide up pulses from earthquakes or from air weapons used for ship-based surveys. The underwater sounds also can produce seismic echoes: When sound waves touring by means of the water meet the bottom, a number of the waves’ power converts right into a seismic wave (SN: 9/17/20). These seismic waves may help scientists “see” underground: Because the penetrating waves bounce off totally different rock layers, researchers can estimate the thickness of the layers. Adjustments within the waves’ pace also can reveal what sorts of rocks the waves traveled by means of.

The echoes recorded within the Pacific Ocean revealed a traditional ocean crust construction beneath three websites alongside the whale’s swim path: sediment layers between 400 and 650 meters thick atop a 1.8-kilometer-thick layer of basalt rock. Beneath that basalt lies a dense oceanic rock generally known as gabbro. The findings recommend that fin whale songs might be efficient seismic instruments to review the seafloor.

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