The 26 December 2004 earthquake off Sumatra induced a disastrous tsunami that struck in South Asian countries. In a similar context, a potential great earthquake off Japan might occur and generate a strong tsunami in East Asia.
The 2004 Sumatra earthquake is the second biggest earthquake (Mw = 9.3) recorded during the last century. It occurred at a depth of 20–30 km, close to an indentation of the Indonesian forearc (Figure l). The rupture propagated about 1200 km northward and terminated north of Andaman Islands.