Cool harmonies

Far from being silent, floating mountains of the Antarctic and Arctic, scientists have shown that icebergs can in fact sing in perfect harmony.

A research team have managed to record seismographic vibrations originating from an iceberg in the Antarctic and found that they produce harmonic sounds with up to 30 overtones.

The researchers suspect that the water flowing within the iceberg’s system of crevasses and tunnels, is stimulating elastic vibrations, similar to those of an organ pipe. The low frequency of the tones means that they are not audible to the human ear despite being as loud as a volcanic tremor.

However, Christian Müller from Fielax - a private company involved in the research - points out that not all organisms have the same hearing range. “The iceberg tremors were recorded in the frequency range between 0.5 and 30 Hz,” he explained to Laboratory News. “Blue whales have a vocalization range between 10 and 100 Hz. Their audible range is expected to be even wider, therefore these iceberg tremor signals might have been heard by blue whales.”

Other than an insight into iceberg dynamics, the team - from the Alfred Wegener Institute for Polar and Marine Research and Fielax - hope that their data will help in the understanding of volcanic activity.

“Understanding these recordings that are so comparable to volcanic tremors might in turn also help volcanologists to explain the causes of volcanic tremors”, explains Christian Müller from Fielax. “In contrast to complex volcanic systems, icebergs have a simpler structure.”

The study, just published in Science, reveals 11 harmonic events on an iceberg identified as B-09A. It shows that the source of the vibrations is mainly the movement of the iceberg alongside the continental slope, and can last up to 16 hours.

Iceberg B-09A produces harmonic tones when vibrated. The resulting sounds could be heard by blue whales.