Connect with us News, Events and Announcements Cascadia’s seismic past Great Earthquakes in Cascadia Cascadia is an unusual subduction zone; it has low levels of seismicity and has not generated a significant megathrust earthquake in historic times. For years, scientists debated whether the Cascadia Subduction Zone was even capable of generating large magnitude earthquakes. Its earthquake potential was established in a detective story involving multiple lines of evidence — including