The San Andreas Fault, probably the subject of more disaster movies than scientific studies so far, has yielded an answer to one controversy with more discoveries being made off Mendocino daily.
“It”s surprising but the offshore area of the San Andreas Fault has never been mapped and there has been very little study of it,” said Chris Goldfinger, the Oregon State University professor now leading a mapping and study of the fault out of Noyo Harbor.
On land, the San Andreas Fault extends from the Salton Sea to Point Arena. The famed fault that caused the 1906 San Francisco earthquake is found about 8 miles off Fort Bragg in about 400 feet of water. Goldfinger”s expedition is mapping a remarkably straight line along the sea bottom.
Goldfinger said the expedition has put to rest a controversy about where the fault returned to land and hopes to learn more about how it interacts with the other major faults at the California Triple Junction, located off the tip of Cape Mendocino.
The San Andreas Fault makes a visible landing on a beach at Point Delgado near Shelter Cove, then disappears into the King Range.
“There were some scientists who believed that that wasn”t the fault that came to land there, but a slide or something else. We”ve pretty much resolved that question,” Goldfinger said
Goldfinger points to a computer screen aboard the research vessel Derek Baylis that shows the fault as if a razor blade carved a straight line from the top to bottom of the monitor.
On the screen the fault line clearly pulls the mouth of a dramatic offshore formation called Noyo Canyon, like an open-mouthed fish on a string. The canyon once may have been associated with the Noyo River but seismic forces have stretched and twisted the gigantic undersea canyon.
“Hundreds of earthquakes like the 1906 earthquake had to be responsible for doing that,” Goldfinger said.
The tiny line of the San Andreas Fault, as seen on the computer screen is actually a 30-foot tall straight cliff edge. That cliff is the dividing line between the western edge of the North American Plate, which is slowly moving south, and the eastern edge of the Pacific Plate, which is moving north.
Offshore, the fault is distinct and ideal for study, not being altered by land-based erosion and development, Goldfinger said.
“It”s all right there and very clear. And nobody has built a WalMart on top of it,” he said.
Arriving this week was a special robot vessel, which Goldfinger describes as a submarine and helicopter hybrid. Biologists from the National Oceanic Atmospheric Administration will use the video to study the rich life the fault creates on and around the sea bottom.
The cliff becomes something like a reef, supporting all levels of the food chain.
“Many of the richest areas for life offshore California are created by faults,” Goldfinger said.
The roughly 6-by-6-foot robot hovers a few feet above the bottom, providing live images of the San Andreas to the crew of the Baylis, an equally unusual piece of research equipment.
The Baylis
With a 79-foot mast, the Baylis, docked at the new Fish and Game Building in North Noyo Harbor is quite a sight.
At first glance, the 65-foot Derek M. Baylis appears to be a lost luxury or racing yacht that ended up in Noyo Harbor like Goldie Hawn”s yacht did in the Fort Bragg-filmed movie “Overboard.”
The Baylis is teaming up with the Pacific Storm, an 84-foot converted fishing boat, creating the need for expansion and modifications of the new dock. The Pacific Storm is specially equipped to study whales and has also made a groundbreaking expedition to study jumbo squid.
While the Baylis was designed by a man famous for creating expensive and speedy yachts, its mission is science, not to be a plaything for the wealthy.
But the speed does help with its mission of being as “green” a research vessel as possible.
“The sleek design helps with our intent for the vessel to have the minimum environmental impact possible,” said Dave Robinson of Sealife Conservation, which manages the Baylis.
The Baylis uses sails instead of fuel wherever possible, to conserve on its ecological footprint.
Although the bottom mapping requires a precision not possible under sail, the stability and boost of the sails helps.
“The Baylis has been consuming 1.6 gallons per hour or less than 40 gallons of diesel per day. The typical research vessel burns upwards of 40 gallons per hour, and some get into the thousands of gallons per day,” said Robinson.
Last year, the research vessel the Pacific Star, nearly four times the size of the Baylis, struck and killed a 70-plus foot blue whale off Fort Bragg, creating local outcry and calls for more regulation of offshore shipping to protect marine mammals.
The smaller vessel makes it much easier to avoid whales. Whale strikes by research vessels are incredibly rare. Goldfinger said the entire crew of the Baylis got marine mammal avoidance training. Because the vessel uses sonar to explore the fault beneath the sea floor, that research is done only in the daylight hours. All operations stop when marine mammals come within a 100-yard perimeter, Goldfinger said.
The crew has seen many humpback whales but none of the more elusive blues or orcas that are sometimes seen.
Like the Pacific Star, a cage does not shield the propeller of the Baylis. Some vessels do take this precaution, despite the constant risk of fouling by seaweeds. Goldfinger said the massive keel, which extends below the propeller, makes it virtually impossible for a whale to come into contact with the propeller.
The bottom mapping itself is done using 240 kHz sonar too high-pitched for marine mammals to hear.
In addition to the sonar used to explore beneath the sea floor that is never used after dark, NOAA also has a third type of sonar in minimal use, which Goldfinger compares to a glorified fish finder, with minimal impacts.
The Baylis is associated with Monterey Bay Aquarium and spends most of its time in the South Bay Area, with a dual mission of education and studying pollution in the ocean.
While the Baylis has helped identify 120 different types of fragmented sea garbage, Robinson said the educational mission is of paramount importance. To that end, SeaLife Conservation helped in an effort to get a ban on certain styrofoam products.
“The bottom line is that single use plastics are the biggest problem,” Robinson said.
