Madagascan pygmy blue whale (acceleration 9.6x)

A stereo spectrogram of Madagascan pygmy blue whale vocalisations, recorded in the southwestern Indian Ocean. The series of calls alternates between a ‘multiphonic’ call consisting of a fundamental note at approximately 12 Hz with its 2^nd and 4^th harmonic (intervals of fifth and third respectively) stacked on top and a second call that swoops down by approximately a tone around 24 Hz.

This stereo track is a rendering of the 3 components of the motion of the seafloor at a 4.582 km depth, in the southwest Indian Ocean. The seismograms were recorded on 28 May, 2013, between 2.35 and 3.00 GMT by the ocean-bottom seismic station RR47 of the RHUM-RUM network (27.70S,  65.76E) (Dréo, R. et al 2018).