A megathrust earthquake occurs in subduction zones where two crustal plates are colliding. They have occurred in the Cascadia Subduction Zone in the past and scientists predict another will occur. The 2012 Chile Earthquake and the 2011 Japanese earthquakes were earthquake megathrust events.
Subduction zone earthquake
struck Chile in 2010, USGS
Subduction zone earthquakes
A earthquake earthquake occurs in subduction zones when two crustal plates are colliding. Most subduction zones occur where an oceanic plate is being forced beneath a continental plate.
Large sections of the two plates become locked together. Stress in the rocks builds up storing energy in the rocks until they break creating great earthquakes that are often magnitude 9.0 or higher. The damage in the picture happened during the 2010 subduction zone earthquake in Chile.
Since 1900 there have been five magnitude 9.0 or greater earthquakes. All these events were subduction zone earthquakes. The rocks rupture as the continental plate is forced over the subducting oceanic plate. This type of movement on a fault is known as a thrust fault earthquake.
Plate overrides subducting plate
The term megathrust earthquakes is commonly used by geologists when referring to great earthquakes in subduction zones because the overridding plate slips over the top of the subducting plate.
Pacific Ring of Fire
The Pacific Ring of Fire is an area around the Pacific Ocean where oceanic plates are colliding with continental plates. Seventy-five percent of the world's active volcanoes are located in the region.
Earthquakes around Pacific Ocean
Approximately eighty percent of all recorded earthquakes occur in the Pacific Ocean basin. The coasts of Alaska, Washington, Oregon and Northern California are all subduction zones where great earthquakes have occurred in the past and will occur in the future.
Earthquake Zones Find out where and why earthquakes occur and why there are earthquake zones.
Moment Magnitude Scale Find out why the moment magnitude scale is used to measure great earthquakes.
1964 Alaska Earthquake The Great Alaskan Earthquake find out why Good Friday saved many people's lives!
New Madrid Earthquakes The New Madrid earthquakes were a series of three very large earthquakes felt by people over almost 2 million square miles.
Earthquake Waves Earthquake waves are produced by the more than three million earthquakes each year.
Megathrust Earthquake Find out why these earthquakes will occur off the coasts of Alaska, Washington, Oregon and California in the future.
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