Humpback whale (Photo credit: Wikipedia)
Endangered humpback whales have converged on the Central Coast of California just as the Diablo Canyon Nuclear Power Plant prepares for seismic testing that has been accused of frightening, deafening, and killing sea life.
The nuclear plant was built at the mouth of a coastal canyon beginning in 1968 above a then-unknown fault line, the Hosgri Fault. In 2008, another previously unknown fault was discovered running along the shoreline.
Beginning in September, Pacific Gas & Electric Co. plans to produce a 3-D map of the shoreline fault's deeper regions by firing high energy air guns dragged in an array behind a research vessel. Hydrophones in the water and geophones on the seafloor would collect data on the sound as it resonates through sea and earth, and the resulting data should help geologists map the fault.
During the survey, an array consisting of 18 active air guns, divided into 2 subarrays, would likely be used. The array would consist of a mixture of Bolt 1500LL and Bolt 1900LLX airguns. The subarrays would be configured as two identical linear arrays or “strings”. Each string would have ten air guns; the first and last air guns in the strings are spaced 16 m apart. Nine air guns in each string would be fired simultaneously (for a total volume of ~3,300 in3), whereas the tenth is kept in reserve as a spare, to be turned on in case of failure of another air gun. The subarrays would be fired alternately during the survey. Each of the two subarrays would be towed ~140 m behind the vessel and would be distributed across an area of ~12×16 m behind the primary vessel, offset by 75 m. The shot interval would be 25 m during the study. The firing pressure of the subarrays is 1900 psi. During firing, a brief (~0.1 s) pulse of sound is emitted. The air guns would be silent during the intervening periods.
via PG&E (pdf)
A 1994 study found that air guns are less harmful to sea life than the chemical explosives formerly used for such studies, but that air guns still are not without risks to fish, marine invertebrates, birds and mammals:
Cetaceans (whales, dolphins, porpoises) have been shown to change their behavior (e.g. moving away from the sound source, reduced dive duration) at threshold distances of between 400 meters and 7 kilometers from the seismic vessel. Whilst it might be assumed that avoidance behavior will protect cetaceans from injury, individual dolphins will sometimes approach survey vessels and even swim under air gun arrays. It is not clear, either, whether transient avoidance may lead to any longer-term disruption of home range in cetaceans."
via Fawley Research Laboratories (pdf)
Diablo Canyon Power Plant in San Luis Obispo County, California, USA (Photo credit: Marya Figueroa)
But isn't seismic testing worth the risk? After all, according to PG&E, "The Project is being undertaken due to public concerns with operating a nuclear power plant in a seismic active area of California post the Fukushima Daiichi emergency."
Some activists don't think that's a good reason:
"Our position is that seismic testing is a threat not only to whales, but to all of us, because it allows Pacific Gas and Electric to delay removal of the nuclear plant from the earthquake fault," according to Stop the Diablo Canyon Seismic Testing, a facebook page launched this summer.
PG&E is already conducting "low energy marine studies" in the region. Although low energy testing is not as loud, the utility warns fishermen: "Marine and commercial boat traffic are encouraged to remain at least a mile away from the vessel while it operates in the area to avoid entanglement with research equipment."
PG&E promises that "procedures have been implemented to monitor and protect marine mammals while the study is underway."
Meanwhile, untold numbers of humpback whales have congregated in the waters PG&E is surveying, including Avila Beach, a community four to five miles from the nuclear plant where this video was filmed last week:
Hat tip to Amy Shore for this story.
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