Burst of seismic activity off the west shore of Vancouver Island focus of joint expedition

In March 2024, Ocean Networks Canada’s real-time monitoring network detected a peak of more than 200 earthquakes per hour at Endeavour field. It was the highest rate of earthquakes there since 2005. Endeavour is a hydrothermal vent field that lies 2,250 metres below sea level on the northern Endeavour segment of the Juan de Fuca Ridge and is approximately 90 kilometres long.

On June 6, the crew of the exploration vessel E/V Nautilus set sail from Sidney harbour for a long-haul journey out to the Endeavour, the most distant of its cabled observatory and monitoring sites. During its 21-day ONCA 2024 Abyss Expedition, the E/V Nautilus will provide maintenance to various seafloor instruments and conduct seafloor mapping exploration with the use of the remotely operated vehicles (ROVs) Hercules and Atlanta.

“The E/V Nautilus is a purposely outfitted ship ideally tailored for ocean exploration and to conduct the complex deep ocean operations that ONC must conduct to ensure that we keep our thousands of sensors delivering data for scientific research, societal protection, and advancing Canada’s blue economy,” says Kate Moran, president and CEO of Ocean Networks Canada.

The 2024 expedition, the eighth being carried out in collaboration with Ocean Networks Canada will last eight months in total. The outage to NEPTUNE (North East Pacific Time-series Undersea Networked Experiments) is one of nine expeditions it will carry out this year. This expedition will last from June 6 to 27.

Other observatories include the Clyoquot Slope (whale fall), Barkley Canyon, Cascadia Basin and Middle Valley and NEPTUNE of the west coast of the Island. These observatories are part of an 800km-loop of fibre optic cable and connected technologies that gather thousands of observations about the ocean floor that an ordinary ship could not register.

The central objective of the 21-day expedition that is currently underway is to deploy, recover, and maintain a variety of sensors and instruments connected to NEPTUNE. NEPTUNE, a University of Victoria Initiative is the first “plugged” in underwater observatory and data collected is picked up and linked directly online. This makes it possible for scientists all over the world to virtually “surf” the ocean floor.

The crew will rely on a multibeam sonar system mounted on the hull of the ship to gather sea floor mapping data. The seafloor mapping data will be available from the National Centers for Environmental Information. Once they analyze the data and identify particular areas of interest, they will deploy the ROVs to collect video and take a range of biological, geological, chemical, and archaeological samples. This will include the data they collect along the spectacular 90km-long Endeavour hydrothermal vent field.
Within the area, there are 16 main venting sites named Bastille, Crypto, Dante, Dudley, Easter Island, Grotto, Hulk, Lobo, MilliQ, Peanut, Puffer, Salut, Smoke & Mirrors, Sully, TP, and Quebec. The vent field is part of a Canadian Marine Protected Area and at its northern end one has been named Sasquatch.

When asked about the names of the vents Meghan Paulson, the expedition lead for ONC said, “They are constantly changing. As minerals in the liquid precipitate around the vents, a solid structure called a chimney is formed on the seafloor. The chimneys resemble underwater stalagmites.” To get a sense of what the activity around the hydrothermal vents (chimneys) looks and sounds like, click here.

“Sometimes the chimneys (otherwise known as smokers) can totally collapse but the vents are still there. The vents can grow 40, 50, metres high”, Paullson said.

The Westshore caught up with crew members Paulson and Allison Fundis, chief operating officer for the Ocean Exploration Trust, on June 7.

Paulson said the decision to head out to Endeavour, the farthest observatory site, “was really for weather considerations,” but they are also keen to respond to the international scientific community’s curiosity about a spike in earthquake activity that happened in that area on March 8. The expedition is part of a yearly maintenance program, said Paulson and is not just a response to that activity. “The maintenance on the cable has to be done each year.”

Some of the equipment they have to swap out “is just not working anymore. It just flat out died,” said Paulson. Some of that equipment is well over 2km underwater.

The team’s work will also provide insight into changes to the seafloor resulting from the ongoing tectonic activity, such as the peak of activity on the Endeavour segment of the Juan de Fuca Ridge from this past March.

The Juan de Fuca Ridge is part of the Cascadia subduction zone. A subduction zone is an area on Earth in which one tectonic plate (giant slabs of the Earth’s crust) is sliding under another. The Juan de Fuca Ridge is an ocean plate that is sliding under the North American continental plate. It has, over time, become wedged. This compressed wedge or ledge is bulging upward between three and 40mm each year, representing the Juan de Fuca Ridge.

Should that ridge someday give way, the seismic measure of that rupture would likely measure between 8.7 and 9.2 on the Richter scale. The resulting earthquake and ensuing tsunami, would be nothing less than devastating for the west shore of Vancouver Island.

This expedition “isn’t happening because we’re worried about the big one,” said Paulson, referring to a long-anticipated earthquake along the west coast—either originating in the San Andreas or the Juan de Fuca Ridge. “Because of sea-floor spreading, the Pacific Plate is actually pulling away from the Juan de Fuca Plate.”

The team will also assist in scientific seafloor surveys with biological and geological sampling, investigating unique coastal marine life and deep-sea ecosystems.

“There are always a few crabs kicking around down there,” said Paulson, “and because of the temperature around the vents—the liquid coming out of them is so hot, and can get up to 400 degrees—there are lots of microorganisms living around them.”

“Our collaboration allows us to combine our expertise and technologies to tackle challenging operations associated with the maintenance of ONC’s world-leading subsea cabled observatory and to also broadly share our work and discoveries with those joining us from shore,” said Fundis. “We are particularly excited to explore the recent seismic activity at Endeavour, which could reveal fascinating insights into the interplay between tectonics and deep-sea ecosystems.”

“The video, data, and samples that result from the expedition are available to any interested researcher immediately through the OET Data & Video Request Form,” said Paulson. Members of the public can live-stream the expedition video on NautilusLive.org, a 24-hour portal bringing expeditions from the field to people on shore via telepresence technology. School and other groups can also request an interactive information session with the Nautilus crew through their ship to shore initiative.

Throughout the expedition, the eyes of the international scientific community will be on the west shore of Vancouver Island.

Sidney Coles, Local Journalism Initiative Reporter, Capital Daily