Seismic recording equipment

Underwater seismic recording equipment is on deck and ready to deploy on Thursday on the research vessel Marcus G. Langseth at Berth 4. Staff photo by Dustin Safranek

The Port of Ketchikan this week hosted the research vessel Marcus G. Langseth, which was taking a short break during its voyage from Seattle to the Gulf of Alaska to collect scientific data.

The Marcus G. Langseth is part of the U.S. Academic Research Fleet and is operated by the Lamont-Doherty Earth Observatory of Columbia University, according to information in an email from Sean Higgins, director at the Office of Marine Operations and senior research scientist. The vessel is owned by the National Science Foundation.

Higgins wrote that the research underway currently is part of the large Queen Charlotte Fault Imaging Project. As a part of that project, ship scientists have been conducting research off Haida Gwaii and the Gulf of Alaska.

A photograph included in the project website at qcfhazards.net/about shows a team of six scientists who are working aboard the ship. Higgins wrote that between 35 and 50 people work aboard the ships during research projects.

Chief Scientist Lindsay Worthington spoke with the Daily News by phone Thursday from her home of New Mexico about her work on the ship this summer. She is a marine seismologist and a professor at the University of New Mexico, and was on the Marcus G. Langseth for five and a half weeks working on the research project.

She said the project was planned to better understand the area and the fault.

“We think we say what types of earthquakes should happen there, but we don’t know really that much about it,” she said.

There have been two major earthquakes along the Queen Charlotte Fault in the past decade — the magnitude 7.8 Haida Gwaii earthquake that struck on Oct. 27, 2012 at Moresby Island, and the magnitude 7.5 quake that hit on Jan. 4, 2013, about 63 miles west of Craig. A smaller, magnitude 6.0 earthquake occurred on July 25, 2014, along the Queen Charlotte fault about 26 miles from Elfin Cove in Southeast Alaska.

According to information on the project’s website, the Marcus G. Langseth features “unique seismic capability” that “allows it to provide both 2-D and 3-D maps of the earth’s structure miles below the seafloor.”

A video showing deployment of the ocean floor seismometers from the Marcus G. Langseth can be found at www.youtube.com/watch?v=LMHDHA__D0s.

The first two legs of the project had been completed with the Marcus G. Langseth, as well as with the Canadian Coast Guard vessel John P. Tully, by the time they docked in Ketchikan, Higgins wrote.

According to the National Science Foundation abstract created for the project, the Queen Charlotte fault often is called the “San Andreas of the North.” A link to the abstract can be found on the project’s website.

The Queen Charlotte fault is a strike-slip plate boundary that separates the Pacific and North American tectonic plates offshore of western Canada and Southeast Alaska, according to information at the website.

“The fault system represents the largest seismic hazard to southeastern Alaska and Canada outside of Cascadia, and caused Canada’s largest recorded earthquake (m8.1) in 1949,” the abstract states.

The project abstract continues to explain that the study currently underway will be the first comprehensive attempt to characterize the plate boundary at depth on a regional scale.

“Using seismic energy from marine acoustic and earthquake sources, the project will measure the depth and extent of seismocity, image the fault zone at depth, and determine velocity and thermal structure across the fault,” the abstract explains.

The FAQ portion of the website explains that data will be collected by using an “array of seismic airguns” as a sound source with “towed hydrophone streamers and ocean bottom seismomenters” to detect and record the returning sound source signals.

The airguns are devices that are towed about 100 feet behind the ship, and at regular intervals release a bubble of compressed air below the sea’s surface. The resulting sound wave is then detected by the “streamers” that act like microphones that also are towed behind the ship.

Shipboard computers arrange the sound wave echoes into acoustic images of the sediment and crustal layers below the seafloor.

Worthington said that the streamers are dragged behind the ship on a 10-mile long cable and the airguns are pulled along on floats. There are separate crews to handle each of those arrays.

She explained that the ship has a permanent crew that are experts on running the equipment, and that the science team really are more like guests who are making sure that all is running according to the plan of the specific study being done.

All those aboard the ship live in comfortable but “pretty practical” rooms aboard the ship and eat together in a mess hall with meals prepared by a cook.

When asked what the most difficult part of the mission has been, she said, “getting off the dock is always the most challenging.”

The logistics and planning have been the biggest challenges in any of the four ocean-going missions she has been on, but she said that the COVID-19 pandemic only amplified the complications this time.

The 2021 ship-based mission was planned to take place in summer 2020, but was canceled due to difficulties caused by the pandemic.

“It’s hard to overstate the challenges and the logistics this year — the impacts to people’s lives — the quarantines,” she said.

The research crew spent a week in quarantine in Seattle in mid-July before leaving on the Marcus G. Langseth on July 18. The ship then traveled up and down the coast between Haida Gwaii and Craig, gathering data before landing in Ketchikan on Aug. 23.

Working as the lead scientist on the Marcus G. Langseth this summer held special importance for Worthington, she said. She had worked on that vessel in 2008 as a graduate student looking for a career in physics that also would be adventurous. Her time on the boat was memorable.

“My dream was to be the chief scientist on the Langseth, so 13 years later — this project is literally a dream come true for me, so that was kind of cool,” she said.

She was quick to point out the importance of the roles held by her fellow lead scientists on the ship. Maureen Walton, a research scientist at the Naval Research Lab, and Emily Roland, a Western Washington University professor worked alongside Worthington during this summer’s project, as did scientists from Canada.

The Langseth was set to depart Ketchikan Friday morning to launch the third short leg of the project, Higgins said.

During that leg, the crew plans to deploy seafloor instruments for about a week. Worthington said that they will place about 28 seismometers along the route as they travel north to Baranof Island. Those instruments will sit and listen for earthquakes before the team retrieves them in the summer of 2022 to assess the data gathered.

Worthington summed up their work on the Langseth saying, “It was a fantastic mission … we were super successful.”

She added that she worked with a “great team of people.”