Giant earthquakes in the world. (a) The locations of M ~ 9 earthquakes since the 20th century are shown by yellow ovals. Red triangles indicate DART stations. Black, yellow and green colors indicate three kinds of plate boundaries, i.e., subduction zones, mid-oceanic ridges and transform faults. (b) Variability of earthquake size in subduction zones. The colored bars represent simplified rupture area: blue, inferred solely from instrumental and written records; green, includes paleoseismological evidence. Numerals denote moment magnitudes. Updated from Satake and Atwater .