Cumulative seismic moment of earthquakes in the Harvard CMT catalog since 1976. The green area shows the contributions
of large earthquakes (magnitude greater than 6.5). The yellow wedge shows the contribution of
the (much more numerous) earthquakes with magnitudes smaller than 6.5. The Sumatra earthquake, by itself, contributed
as much to the total moment release as all earthquakes in the 15 years between 1976 and 1990. Great earthquakes are earthquakes of magnitude 8 or greater.
Credits: Goran Ekstrom, Harvard University.