Juan de Fuca Plate. The Juan de Fuca Plate is smaller than most oceanic plates but its motion is still capable of generating large earthquakes. Subduction zone earthquakes occur when an area at the interface between the plates ruptures. These earthquakes can be very large but are uncommon. The last large subduction earthquake in the Cascadia region happened about 300 years ago.
Shallow earthquakes occur in faults within the North American crust and are far more common.
About a thousand crustal earthquakes are recorded annually but most are too small to be felt. However, a few major crustal earthquakes have occurred. Deep earthquakes, including the recent Olympia earthquake, occur within the subducting Juan de Fuca Plate. Like the shallow events, deep earthquakes are normally small but a few damaging deep events have occurred within the last century. The damage amounts have been adjusted to todays dollars.