What are the three main types of earthquakes?
The Pacific Northwest is host to three kinds of earthquakes revealed in this Flash rollover. Subduction zone great earthquakes, shallow crustal quakes, and earthquakes within the subducting plate. Scroll over the colored spots for date, magnitude, and location for the smaller earthquakes and additional details for the larger.
VIEW the interactive in a separate tab, by clicking on "Open Resource" then scroll over named features. (Note some browsers lack the plugins for rollovers.)
IRIS may be discontinuing these interactive animations in 2020. This file is an HTML5 file that uses a browser to view.
Subduction zones show that there are 3 distinct areas of movement in the overlying plate:
GPS can record the movement of the leading edge of the overlying continental plate in a subduction zone. The plates are locked and the overlying plate is forced back. When friction is overcome and strain is released, the GPS receiver will snap back toward its original position.
Subduction-zone megathrust earthquakes, the most powerful earthquakes in the world, can produce tsunamis through a variety of structures that are missed by simple models including: fault boundary rupture, deformation of overlying plate, splay faults and landslides. From a hazards viewpoint, it is critical to remember that tsunamis are multiple waves that often arrive on shore for many hours after the initial wave.
This UNAVCO animation compares Japan's subduction zone at the location of the 2011 earthquake with a mirror-image subduction zone in the Pacific Northwest. There are many similarities.
We encourage the reuse and dissemination of the material on this site as long as attribution is retained. To this end the material on this site, unless otherwise noted, is offered under Creative Commons Attribution (CC BY 4.0) license
