Far off the West Coast, deep beneath the ocean, the Earth is slowly moving. We can’t see it happening, but those movements matter a lot for life on land—especially here in Cascadia.
During the ONCabyss Summer 2025 expedition, Ocean Networks Canada (ONC) spent time tracking these hidden shifts along the Cascadia subduction zone, where one tectonic plate is sliding underneath another. This kind of plate movement can lead to some of the strongest earthquakes on the planet, which is why scientists are paying close attention.
On Leg 2 of the expedition, the team replaced one of their seafloor instruments—small but powerful devices that act like reference points on the ocean floor. These instruments help scientists measure how the plates are moving over time. Keeping them in good working order is key to collecting reliable data year after year.
Since GPS doesn’t work underwater, ONC uses a clever helper called a wave glider. This small, robotic vessel floats on the ocean’s surface, powered by waves and sunlight. As it travels above the instruments below, it sends sound signals down to the seafloor and listens for the response. By matching that information with GPS data, scientists can figure out exactly how the seafloor is shifting—even when the movement is just a few centimeters a year.
By repeating this work every year, researchers can tell whether the plates are locked in place or slowly creeping past one another. This kind of research may be happening far offshore, but it impacts communities across the Pacific Northwest. By learning more about how earthquakes begin beneath the ocean, scientists are helping communities better understand, prepare for, and mitigate the impacts of Cascadia Subduction Zone earthquakes and tsunamis.
- Storymap Link: #ONCabyss Summer 2025 Ocean Expedition Highlights
- Ocean Networks Canada info page on the research: Monitoring for megathrust earthquakes
- Links to ONC’s underwater cameras: Live Cameras | Ocean Networks Canada
Surviving Cascadia 
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