UO-Led Cascadia Initiative Focuses on a Shifting Underwater Continental Plate

Where a major earthquake and the Northwest are concerned, the question isn’t “if ”—it’s “when.”

The region is due for a massive earthquake and tsunami in the Cascadia Subduction Zone, a coastal area stretching from Canada to Northern California where the continental plate is slowly overriding the ocean floor. Scientists at the University of Oregon are leading a national team that is collecting data that will ultimately describe the risk to the Pacific Northwest. Earthquake investigators may be the primary beneficiaries, but the project aims to inspire young scientists and yield readily available data for biologists and other researchers around the world.

Doug Toomey, a UO geophysicist, is leading the Cascadia Initiative Expedition Team, which is funded by the National Science Foundation and $10 million in federal Recovery and Reinvestment Act dollars to study questions ranging from megathrust earthquakes to volcanic arc structure to the formation, deformation, and hydration of the area’s tectonic plates. The damage caused by the 2011 earthquake and tsunami in Japan illustrates that there are still many major unknowns regarding the risk from a catastrophic event.

“The U.S. is, in some ways, in the early stages of evaluating and mitigating risk in the Pacific Northwest,” Toomey said. “This study will lay the groundwork for many current and future efforts.”

Aboard the Atlantis

Between June 25 and July 9 of 2013, UO senior physics instructor Dean Livelybrooks and a team of national scientists on board the research vessel Atlantis retrieved ocean-bottom seismometers that have been collecting data on earthen vibrations for a year. On board the 270-foot-long vessel, the team moved south from Astoria to Cape Mendocino, off California’s north coast, recovering the monitors along the way.

Livelybrooks’ colleague in leading the trip was Anne Trehu, a seismologist at Oregon State University, who said there’s never been an offshore earthquake research project on the scale of the initiative. Over a four-year period, seventy seismometers are in use to measure vibrations in the ocean floor at approximately 140 sites off the coast, from Canadian waters to Northern California.Earthquake activity can be affected by water that was trapped in the oceanic crust and sediments that are released as the oceanic plate descends beneath the continent, ultimately weakening faults and allowing them to slip. But water affects earthquake activity in ways that aren’t fully understood, and the Cascadia project will shed light on that relationship. A better understanding of plate dynamics will yield better assessments of what might happen in an earthquake off the coast.

“The better we can anticipate, the better we can focus our resources on what’s important,” Trehu said—“things like building codes, public education, evacuation planning.”

The underwater hunt begins

Retrieving the seismometers was challenging work. The team managed rough waters while retrieving instruments that weigh as much as 1,600 pounds each and were deployed at depths of up to 2,500 feet—about a half-mile. Working within a two-week window, the team recovered all thirty of the monitors.

Fortunately, the scientists had a mechanical advantage: They used Jason, a remotely operated vehicle (ROV) owned by Massachusetts-based Woods Hole Oceanographic Institution, to locate the instruments and help bring them on board. About the size of a Mini Cooper automobile, Jason is a box-like robot equipped with multiple cameras and two ominous-looking manipulator arms that end with claw-like jaws that can lift marine equipment the size of refrigerators. The ROV is tethered to a control room on the ship through a long cable full of communication wires. When the operator in the control room presses a button or moves a joystick, Jason’s thrusters fire up and he starts moving along the ocean floor, at depths of as much as four miles.

The ROV was used to attach floats to the seismometers that would allow a crane on the boat to lift the instruments on board. Livelybrooks was often in the control room during Jason dives to record footage of the marine life seen through Jason’s underwater cameras. Livelybrooks uses the ocean research trips to get college students excited about STEM careers—science, technology, engineering, or mathematics.

Inspiring the scientists of tomorrow

Each year, about one million U.S. high school freshmen declare interest in a STEM-related field—more than one in four. By the time they graduate, more than half will lose interest in a STEM career. Livelybrooks is part of a national effort to feed the nation’s growing need for scientists and engineers by increasing interest in STEM careers among students in K–12 and community colleges.

The Atlantis trip was the third in which Livelybrooks found space for community college students to participate. The students log earthquake data, work with seismology equipment, and experiment with a variety of telecommunications, all under the eye of experts in those fields.

“There are a lot of people in community college who have never really met a scientist or engineer and don’t know what those jobs are like,” Livelybrooks said. “Out here, they’re witnessing lots of scientists and engineers in action and working as a team. They’ll be able to go back to their institutions and say, ‘This is what we did out on the Atlantis.’”

“My hope,” he added, “is that that will serve to inspire their peers to also consider careers as scientists and engineers.”

Scientific data for all the world to see

Haley Domer, accepted to Portland State University, tracked the ship’s locations and movement and also working with bathymetry, the study of underwater depths of ocean floors.

“The thing that’s been most interesting to me is the rock sample we brought up, and the ocean bottom,” she said. “I think [this experience] will be good for me to figure out what I want to do.”

While the earthquake data will be vitally important, geologists won’t be the only ones who benefit from the initiative. The seismometers are also measuring tidal behavior and picking up signals from sea animals including fin and blue whales. Biologists, for example, will be able to study whale movements during winter periods when observation is difficult.

And in an uncommon arrangement, the data that is collected will quickly be made available on the Internet, rather than just to a select group of researchers involved in the project. That will further understanding of earthquake activity, not just in the Pacific Northwest but also across the globe. Toomey expects researchers from all over the world will access the data that is being collected.