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.

In 2004 a Magnitude 9.1 interplate subduction earthquake triggered a tsunami that killed over 230,000 people. Yet a nearby magnitude 8.7 intraplate earthquake in 2012, caused little damage and generated minimal ocean waves. This animation describes the different tectonic settings of the two plates, and how the Indo-Australian plate seems destined to become two distinct tectonic plates: the Indian and the Australian plates.

UPDATED (Jan, 2022) - New Ending On Convection 
Lithospheric plates are part of a planetary scale thermal convection system. The energy source for plate tectonics is Earth’s internal heat while the forces moving the plates are the “ridge push” and “slab pull” gravity forces.

 GPS records 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. 

TEASER:  Intro to IRIS's "Geographic Region" series. Our "World Series" addresses regional tectonic forces and resulting recent and historic earthquakes around the world (ex. Japan, Alaska, Peru-Chile, Central America, Mexico, Pacific Northwest).