FIGURE 1. Seismic activity before, during and after the great Sumatra–Andaman earthquake (including events beneath the Andaman Sea).

Each circle in this space–time diagram represents an earthquake, with size increasing with magnitude as shown by the scale. The two largest events — on 26 December 2004 (day 0) and 28 March 2005 (day 90) — are identified by stars. The rupture of 26 December 2004 extended northwards for at least 1,300 km, that of 28 March 2005 southwards for 300–400 km. More than 5,000 aftershocks have been located, and activity continues across the region. (Data from ref. 13.)