Unusually, this region is buffeted by triple junctions at both its north and south end: the Queen Charlotte Fault and Explorer Ridge to the north, and the Mendocino Triple Junction to the south, where it meets the Gorda plate.
John Adams used turbidites, deposited by synchronous turbidity currents, to determine that this geologic zone erupts in an earthquake around every 590 years, plus or minus 170. Unusually, this region is buffeted by triple junctions at both its north and south end: the Queen Charlotte Fault and Explorer Ridge to the north, and the Mendocino Triple Junction to the south, where it meets the Gorda plate. Unlike the nearby San Andreas fault, this region is capable of producing a 9.0+ magnitude megathrust earthquake colloquially dubbed the coming "Big One". This region is formed by the Juan de Fuca plate being subducted underneath the North American plate. For 10 points, name this region in the Pacific Northwest named for a nearby mountain chain that includes Mount St. Helens and Mount Rainier.
John Adams used turbidites, deposited by synchronous turbidity currents, to determine that this geologic zone erupts in an earthquake around every 590 years, plus or minus 170.
Cascadia subduction zone [or CSZ; or Cascadia subduction margin; or Cascadia fault; prompt on Pacific Northwest or Ring of Fire]