Sumatran Earthquake figures
Location of the mainshock (largest symbol) and major aftershocks of the 26 December 2004 great Sumatran earthquake. The focal mechanism "beachball" diagrams all show nearly pure thrust as the quakes occurred about 20 kilometers beneath the surface, on the Indonesian subduction zone. See Earthquakes in a Nutshell for more background.
Seismograms from the Global Seismographic Network (GSN), arranged by distance (in degrees around the Earth) from the Sumatra epicenter. The strongest waves are the surface Rayleigh waves, which reached the opposite side of the Earth in about 90 minutes and continued to circle the planet several more times before dying out. The initial P waves traversed the Earth in about 20 minutes and the S waves took about 50 minutes. To the right of "R3" is the trace of a magnitude-7 aftershock. Ordinarily that would be a major event of its own. See more about the seismology of this quake at the IRIS special page. The GSN produced records of excellent quality in real time throughout this enormous seismic event.
