Acoustics Today: Sound and Marine Seismic Surveys by Dr. Robert Gisiner

Sound and Marine Seismic Surveys

Underwater sound has been used for over 50 years in marine geological research and exploration.

Introduction

Sound has been used as a tool for imaging geological structure on land and in water for more than 50 yrs (Figure 1). Compressed air sources, referred to as airguns, have been the dominant marine sound source since the 1960s (Parkes and Hatton, 1986). Whether on land or in the water, the basic principle is that the acoustic energy from the sound source is reflected and refracted by the rock layers beneath the surface back to the receivers, thereby enabling geophysicists to reconstruct an 'image' of the underlying geology, in a way that is analogous to medical ultrasonic imaging (Figure 2).

On land, the acoustic energy comes from buried explosives or vibratory sources that are in contact with the ground, returned vibrations are received by geophones (Sheriff and Geldart, 1995). Little or no energy is transmitted to the air to be perceived as sound.
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