Perils of offshore exploration.
newleftreview.org
Tapping ‘unconventional’ deposits requires advanced technology. Before an offshore oil or gas well can be sunk, the area needs to be mapped, and the most accurate way to do that is via a process called ‘seismic exploration’. This involves a ship slowly traversing the ‘acquisition area’ – industry jargon for the place being mapped – trailing pneumatic guns and microphones behind it, sometimes on 10km-long lines. The air-guns fire regular sound blasts into the water; the microphones record the echo bouncing back from the seafloor. To penetrate the sub-seafloor, where oil and gas may be found, the blasts have to be extremely loud. At an unimaginable 240 decibels, they are among the loudest sounds humans can produce. For comparison: these are louder than the sound produced by the explosion of an atomic bomb. To map the acquisition area, hundreds of thousands of such blasts are required. The guns fire every ten seconds, 24 hours a day, for months on end. At this rate the number of blasts adds up quickly. By the time of Sunak’s announcement, SAExploration’s vessel in the North Sea would have fired off almost one million blasts over the first 108 days of its mission.
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The blasts are no doubt keenly heard by cetaceans – dolphins and whales – who experience sound in distinctive and complex ways (they are able to ‘see’ and feel with sound). Humans can hear frequencies between 20 and 20,000 hertz (Hz); Bottlenose dolphins can hear up to 160,000 Hz. They use their ultra-precise hearing to locate food, to navigate and to communicate. Hundreds of thousands of nuclear bomb-volume blasts ripping through their habitat is likely to affect their senses in ways we cannot understand. It is an act of phenomenal violence. What of the other inhabitants of the overfished, acidifying ocean? What happens when microorganisms are hit with a 240-decibel sound wave? The short answer is nobody knows; it hasn’t been adequately studied.