The largest earthquake in 40 years across swathes of Asia emerged on Monday as the death toll soared over 17,000 and hopes faded for many thousands still missing.

Sunday's quake, the fourth largest recorded since 1900 and measuring 9.0 on the Richter scale, occurred after a rupture on the Indian Ocean seabed caused by the violent grinding of two tectonic plates.

Walls of water up to 10 metres (33 feet) high were reported around Asia, roaring ashore with unstoppable speed, sweeping people off beaches, flattening hotels and homes, uprooting trees and overturning cars.