The Indian Ocean: from basin to basin


The structure of the bottom of the Indian Ocean was almost unknown before the 1950s. Then the studies of the ocean floor enjoyed success: researchers from around the world obtained a multitude of data on their research ships and, as a result, a Geological-Geophysical Atlas of the Indian Ocean was compiled by 1975.

Today scientists from the Institute of Oceanology RAS have performed a large volume of work on summarizing already contemporary data of the deep seismic probing of the Earth’s crust and mantle in the region of the Indian Ocean. For the first time they compiled a computer database on all basins of the ocean, including over 170 geophysical measurements of just the deepwater ocean basins (altogether there are far more measurements on the ocean) made by Russian, German, American and British expeditions.

The oceanologists created models of the Earth’s crust and mantle for each oceanic depression. Their comparative analysis has shown that the basins in the Indian Ocean are developing irregularly and with varying speed; they have different depths of the main layers of the crust. The features of many basins were also clarified, such as the Somali, Central and Wharton. For the Somali Basin the scientists constructed a chart of the dependence of the depth of the Earth’s crust on its age, where increases are evident 50-70 and 120-140 million years ago. These figures correspond with a depth of the crust of 6-7 and 9-11 kilometres. It was learnt that the depth of the crust as a whole grows linearly from 4 kilometres (in a young crust about 20 million years old) and up to 10 kilometres in the crust aged 130 million years.