WWU’s Emily Roland and Six Undergrads Spend Week at Sea Gathering Data from the Queen Charlotte Fault off SE Alaska
Communication is a two-way street; when one speaks, the other listens, and tries to interpret the sometimes subtle signals in the language.
But when you’re a geophysicist, and what you’re listening to are the not-so-subtle signals of one of the most active fault systems in the world – and then the fault starts speaking in a wholly different language than you expected it to – that’s when the conversation gets REALLY interesting.
This is the situation that Western Washington University Assistant Professor of Geology Emily Roland finds herself in; her erstwhile conversation partner, the Queen Charlotte Fault off the British Columbia and Southeast Alaska coasts, has begun a new dialog with the world’s geologic community in a wholly new and unexpected way.
The Queen Charlotte Fault is a strike-slip fault. It’s where two plate boundaries – in this case, the Pacific Plate and the North American Plate, meet. Strike-slip faults are characterized by the two plates moving in opposite directions, but along the same axis – sort of like two cars passing each other on a two-way street.
“These types of faults can be very active in terms of seismic activity, as the plates grind and lurch in their directions of movement, releasing that energy as earthquakes,” Roland said. California’s San Andreas Fault is perhaps the most well-known strike-slip fault in the world, and the Queen Charlotte Fault is known to geoscientists as “The Sister to the San Andreas,” because of their similarities in both size and earthquake activity.
Rumblings and grumblings
Most people know that the Pacific Northwest is a part of the Ring of Fire – but in reality, the margin of the Pacific hosts different kinds of plate boundaries, with different kinds of earthquakes. The Queen Charlotte Fault lies between two zones along the Ring of Fire in the northeast Pacific where plate boundaries clash, connecting the Cascadia and Alaska subduction zones. The Queen Charlotte transform margin has had five significant earthquakes of magnitude 7 or higher in the last 100 years alone, most recently a 7.8 on Oct. 28, 2012, and another 7.5 only a few months later on Jan. 5, 2013. It was these events that really got geoscientists’ attention, not just because of their size or how close the fault is to Alaska and coastal BC, but because of how the fault slipped during the events.
“What happened in 2012 is why we are out there now, looking, listening, and mapping that fault,” Roland said.
In a nutshell, Roland said that during the 2012 earthquake, the QCF acted like a thrust fault – where one plate rides over the top of another – not a strike/slip fault as you might expect if you were looking at large-scale plate motions. This is doubly a concern because thrust ‘quakes are the type most commonly associated with another major threat to the Pacific Northwest – tsunami.
“This took many scientists by surprise. We usually can anticipate the type of fault slip that occurs during the largest events on a given plate boundary. The M7.8 really got our attention – because strike-slip faults just don’t typically act this way,” she said. “By the time the second M7.5 earthquake happened in early 2013, the fault was moving as we would expect along a strike-slip margin again, a few 100 miles to the north. This highlights how complicated the margin is and how much it changes from south to north.”
For the last two summers, Roland, as part of a $900,000 grant from the National Science Foundation’s Division of Ocean Sciences, has first placed and then retrieved a year later a set of ocean-bottom seismometers that listen to, and record, the activity of the QCF for a year at a time. The seismometers, on loan from the Woods Hole Oceanographic Institution, were dropped off along the fault in the summer of 2021. This past September, Roland led a team of six Western undergraduates aboard Columbia University’s R/V Marcus G. Langseth on a cruise to retrieve the seismometers, getting back just in time for the start of classes.
“The goal of the grant is to better understand what is controlling earthquakes along the fault, especially the magnitude 7 and 8 quakes,” said Roland. “And of course to figure out how a fault this size can demonstrate such variable slip behavior, that is potentially so dangerous.”
Next for Roland, with the help of some of her students, is to examine the data from the seismometers and the detailed new maps of the fault zone made using the Langseth’s bathymetric sonar.
“All this new data should tell us more about what the fault is doing and potentially why and how it is behaving in such a curious way,” said Roland.
Bringing in help
Roland was able to enlist the aid of a group of WWU undergraduates for the cruise this past September, and Jacob Tomer, Gabe McInnis-Hernandez, Declan Tracy, Emma Martin, Maddie Bergeron and Richard Gordon-Rein did not disappoint.
“I can’t speak highly enough of what these students went out there and accomplished. They were treated like grad students, with the same responsibilities, and they were awesome. They operated the sonar system, retrieve the seismometers, stood watch on ship – everything,” Roland said.
The importance of the research– and the experience they gained from participating in it – was not lost on the students.
Jacob Tomer, a Marine and Coastal Sciences (MACS) major from Bainbridge Island, said researching the fault and its activity was a matter of public safety.
“This work is important because of the fault’s proximity to major cities along the coast. Understanding the patterns of earthquakes in the region, large and small, is paramount to the safety and well-being of those communities,” he said.
McInnis-Hernandez, a MACS major from Lake Forest, said the experience gained at sea was invaluable.
“Being at sea for any extending period of time is intimidating, especially for your first time. Now that I have done it once, I will feel much more comfortable doing it again in the future, which I really hope to do at some point,” he said.
Emma Martin, a MACS major from Rapid City, South Dakota, described the impact the week of fieldwork aboard ship had on her.
“This entire experience has been absolutely amazing. I had a fantastic time on the cruise and made some really amazing friends. In addition, this experience has helped me grow as a scientist and even changed my prospective goals for my future. Marine geophysics is looking better and better by the day,” she said. “Every memory of this experience has been positive -- besides getting seasick.”
For more information on Emily Roland’s research on the Queen Charlotte Fault or the latest cruise funded by the National Science Foundation, contact her at email@example.com.