A prime example is the 2011 Tohoku earthquake that rocked Japan.Ĭascadia is seismically very quiet compared to other subduction zones – but it’s not completely inactive. Subduction systems – where one tectonic plate slides over another – are capable of producing the world’s largest known earthquakes. The Juan de Fuca plate meets the North American plate beneath the Cascadia fault. The Juan de Fuca, a small oceanic plate, is being driven under the North American plate, atop which the continental U.S. The Cascadia subduction zone is a region where two tectonic plates are colliding. ![]() We’ve identified regions that are rising up beneath these active sections which we think are leading to the observable differences along the Cascadia fault. Our research tries to answer these questions by constructing images of what’s happening deep within the Earth, more than 90 miles (144 km) below the fault. But why do these variations exist and what gives rise to them? The northern and southern sections are much more seismically active than the central section – with frequent small earthquakes and ground deformations that residents don’t often notice. Geophysicists have known for over a decade that not all portions of the Cascadia megathrust fault behave the same. Scientists know it has the potential for large earthquakes – as big as magnitude 9. That doesn’t mean it will stay quiet, though. There haven’t been many widely felt quakes along the Cascadia megathrust, certainly nothing that would rival a catastrophic event like the 1989 Loma Prieta earthquake along the active San Andreas in California. This geologic fault has been relatively quiet in recent memory. It’s home to the Cascadia megathrust fault that runs 600 miles (966 km) from Northern California up to Vancouver Island in Canada, spanning several major metropolitan areas including Seattle and Portland, Oregon. ![]() ![]() Most people don’t associate it with earthquakes, but they should. The Pacific Northwest is known for many things – its beer, its music, its mythical large-footed creatures. What’s going on about 90 miles (150 km) below the Earth’s surface? Image via Good Free Photos.īy Miles Bodmer, University of Oregon and Doug Toomey, University of Oregon
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