Slide Words: Cumulative Moment Release since 1976

Slide Image: A graph showing that the December 26, 2004, Sumatra-Andaman Islands Earthquake, by itself, contributed as much to the cumulative seismic moment of earthquakes as all earthquakes in the 15 years between 1976 and 1990.

The largest roughly wedge-shaped area on the graph shows the contributions of large earthquakes (magnitude greater than 6.5). This wedge increases in size from 1976 to 2004.

A small wedge below the large wedge, shows the contribution of the much more numerous earthquakes with magnitudes smaller than 6.5.

Great earthquakes, which are earthquakes of magnitude 8 or greater, are indicated along the top line of the graph by stars. There are four stars between 1976 and 1980. The next star is in 1986; the next in 1990; six stars between 1995 and 1999; four between 2000 and 2004, including the December 2004 earthquake.

The December 2004 earthquake was magnitude 9.0 and is represented by the tall column on the right side.

Image Credit: Goran Ekstrom, Harvard University