Last week's massive earthquake off the coast of Indonesia had a profound impact on the region's geography, causing islands literally to change position, say scientists.

The earthquake was caused by a build-up of pressure at the junction of two of the 'tectonic' plates on the Earth's crust, one beneath the Indian Ocean and the other on which the Indonesian island Sumatra lies.

The two plates have been pushing against each other for two centuries, shifting eastwards by about six centimetres each year. The 26 December earthquake, however, caused a 1,200 kilometre long rupture, and forced the floor of the Indian Ocean to shift by 15 metres towards Indonesia.

As the Indian Ocean plate was forced beneath that of Sumatra, the deadly tsunami was unleashed.

Scientists say that maps will have to be redrawn as islands such as Sumatra and India's Nicobar and Andaman Islands have physically shifted, and may have also altered in elevation.