SEISMIC BLASTING IN THE SOUTHERN OCEAN
Southern Ocean under threat
An enormous 5.5 million hectares of the Otway Basin is currently under proposal for seismic blasting, to search for new gas. Multinational companies TGS and Schlumberger are seeking approval to seismic blast for 400 days, in an area of the Otway Basin almost the size of Tasmania. Seismic blasting will have devastating impacts on our marine life, including up to 25 whale species which migrate through the proposed area each year.
What is Seismic Blasting?
Seismic blasting is the first step in offshore oil and gas exploration, and is used to locate fossil fuels under the seabed. Survey ships tow an array of airguns and receivers behind their stern, covering an area of ocean in a grid pattern. The airguns emit blasts that send a deafening sound wave up to 15km deep into the ocean floor; the signals bounce back up to the receivers and identifies potential fossil fuel reserves. The blasts are up to 250 decibels (that’s louder than the Hiroshima bomb) and go off every 10 seconds, 24 hours a day, 7 days a week, often for months on end. Because sound travels significantly further and faster under water than through air, the blasts can be heard in the ocean up to 4000 kilometres away. Moreover, the scale used to measure decibels is not linear, but logarithmic, so that 20 decibels, for example, are ten times the intensity of 10 decibels; 30 decibels are a hundred times more intense than 10 decibels, and so on. A 250-decibel seismic blast is one million times more intense than the loudest whale calls.
The Impacts of Seismic Blasting
Seismic blasting is known to maim and kill marine animals and displace fisheries. The proposed area is of critical importance to endangered marine life, commercial fisheries, and ecosystems associated with the biologically important, Bonney Upwelling.
Seismic blasting has been proven to damage and kill zooplankton within a radius of at least 1.2 kilometres with every blast. When this impact is combined with tidal flows moving in an east and west direction across the bottom of Australia, vast rivers devoid of zooplankton are created. Zooplankton are the foundation of life in the ocean and include the juvenile stages and larvae of many marine species. Any impact to zooplankton communities can have huge impacts on whole ecosystems.
The blasts created by seismic survey reach levels of up to 250 decibels. Sounds this powerful can deafen whales, disrupting their feeding, breeding and migration. This creates even greater threats to some of the already endangered whale species which migrate through the proposed area each year.
TGS and Schlumberger's proposal
TGS and Schlumberger are seeking a permit that would allow them to seismic blast 5.5 million hectares of the Otway Basin, over a 400 day period. Their project is designed to service multiple clients, and to provide geological information that can be sold to gas exploration companies, worldwide. The project is known as ‘frontier exploration’ because the area of ocean has not been released by the Australian government in the form of titles. This data would be the property of SLB/TGS and would be sold to prospective offshore developers. Much of the area in this proposed site was previously 2D-seismic blasted by Schlumberger in 2019/20, and the site also encompasses areas that have been blasted in the last 5–10 years, meaning some parts of our Southern Ocean will be repeatedly impacted by seismic blasting.
Schlumberger under criminal investigation
Schlumberger is currently under criminal investigation, for breaches to its environmental plan during its last seismic blasting project in the Otway Basin in 2020. These breaches included, blasting within a title (area) that Schlumberger had not been granted a permit for.
Schlumberger have a history of non compliance. In 2019, during a seismic blasting project in the Otway Basin, the SLB flagship the Nordic Explorer blasted over a dump site for WWI and WWII chemical and artillery weapons. It remains unknown, despite inquiries, what impact these blasts had on the canisters of chemicals. In late 2022 the Schlumberger corporation rebranded itself as SLB. It is one of the largest companies, in any industry, on the planet, and one of the most secretive. In April 2015, it was handed the biggest corporate criminal fine in US history, along with three years’ corporate probation, for violations of sanctions in Iran and Sudan.
If you're keen to read more about seismic blasting and the proposal by TGS and Schlumberger, click the link to our fact sheet here.