Paleoseismological studies of tsunami deposits have been
conducted since 2004 in Sumatra Island, Thailand
, the Andaman and Nicobar Islands and
India. These studies have shown geological evidence
of past tsunamis in the regions. The last earthquake was
estimated to have occurred around AD 1300–1450 in
Thailand, AD 1290–1400 in Sumatra, AD 1250–1450 near
the Andaman and Nicobar Islands, post AD 1600 in South
Andaman Island, and around AD 1020–1160 along the
Indian coast. These various dates may indicate that the last
great earthquake was not exactly the same as the 2004
Sumatra-Andaman earthquake.