This animation shows every recorded earthquake in sequence as they occurred from January 1, 2001, through December 31, 2015, at a rate of 30 days per second. The earthquake hypocenters first appear as flashes then remain as colored circles before shrinking with time so as not to obscure subsequent earthquakes. The size of the circle represents the earthquake magnitude while the color represents its depth within the earth. At the end of the animation it will first show all quakes in this 15-year period. Next, it will show only those earthquakes greater than magnitude 6.5, the smallest earthquake size known to make a tsunami. Finally it will only show those earthquakes with magnitudes of magnitude 8.0 or larger, the "great" earthquakes most likely to pose a tsunami threat when they occur under the ocean or near a coastline and when they are shallow within the earth (less than 100 km or 60 mi. deep).
This time period includes some remarkable events. Several large earthquakes caused devastating tsunamis, including 9.1 magnitude in Sumatra (26 December 2004), 8.1 magnitude in Samoa (29 September 2009), 8.8 magnitude in Chile (27 February 2010), and 9.0 magnitude off of Japan (11 March 2011). Like most earthquakes these events occurred at plate boundaries, and truly large events like these tend to occur at subduction zones where tectonic plates collide. Other, much smaller earthquakes also occur away from plate boundaries such as those related to volcanic activity in Hawaii or those related to wastewater injection wells in Oklahoma.
You can view a YouTube version of this animation here.
The great majority of earthquakes occur at tectonic plate boundaries.
The majority of great earthquakes (magnitude 8.0 or larger) are megathrust earthquakes that occur at convergent plate boundaries, also called destructive margins or subduction zones.
For an earthquake to pose a tsunami hazard it needs to vertically move the seafloor; therefore it needs to be large (typically 8.0 or larger), under or near the ocean, and shallow within the earth (less than 100 km).
During the 15-year period covered by this animation 20 earthquakes had a magnitude of 8.0 or larger:
June 23, 2001, MW = 8.4, near coast of southern Peru
September 25, 2003, MW = 8.3, Hokkaido, Japan
December 23, 2004, MW = 8.1, north of Macquarie Island (south of New Zealand)
December 26, 2004, MW = 9.1, northern Sumatra and Andaman Islands
March 28, 2005, MW = 8.6, northern Sumatra, Indonesia
May 3, 2006, MW = 8.0, Tonga
November 15, 2006, MW = 8.3, Kuril Islands, Russia
January 13, 2007, MW = 8.1, east of Kuril Islands, Russia
April 1, 2007, MW = 8.1, Solomon Islands
August 15, 2007, MW = 8.0, near coast of central Peru
September 12, 2007, MW = 8.4, southern Sumatra, Indonesia
September 29, 2009, MW = 8.1, Samoa Islands
February 27, 2010, MW = 8.8, offshore of central Chile
March 11, 2011, MW = 9.1, near the east coast of Honshu, Japan
April 11, 2012, MW = 8.6, off the west coast of northern Sumatra, Indonesia
April 11, 2012, MW = 8.2, off the west coast of northern Sumatra, Indonesia
February 6, 2013, MW = 8.0, west of Lata, Solomon Islands