Seismic Surveying & Airguns

seismic air guns firing

Seismic surveys are performed in order to map the ocean floor, including depth, location and structure of geophysical resources, often in the form of oil and gas reserves. The first marine seismic surveys were carried out in the 1950’s using chemical explosives. Modern surveys have taken a more gentle approach, using airguns to create low frequency sonic waves. While air guns are less destructive than its chemical predecessors, introducing loud anthropogenic noise pollution into the ocean environment has detrimental effects on the ecosystem. Scientists have confirmed that seismic surveys increase noise levels to twice the normal level and impact marine life by disturbing their habits essential for survival.

The technique used during seismic surveys to prospect for oil and gas offshore is particularly detrimental to marine environments. Companies use high-volume air guns that are so loud, you can see the water rise and fall when the guns go off.  The devices, towed behind vessels that trace grids on the ocean surface, emit blasts of compressed air that both energy companies and conservationists acknowledge are at least as loud as a roaring jet engine. The use of airguns unavoidably results in noise pollution in the surrounding area.

Regulatory bodies have taken steps in reducing the impact of these surveying techniques on the marine environment. The Canadian government has introduced regulations for the Mitigation of Seismic Sound in the Marine Environment 

These regulations inculde the use of passive acoustic monitoring systems, including hydrophone arrays, to monitor and mitigate for marine wildlife in order to protect them. Regulations pay particular attention to at-risk and endangered species.

The in-house technologist at Ocean Sonics is a certified PAM operator.