Discuss how the changes in shape and sizes of continents and ocean basins of the planet take place due to tectonic movements of the crustal masses.

Mantle convection

Arthur Holmes proposed that convection currents driven by radioactive heat drag the overlying plates.

Ridge push and slab pull

New crust slides off mid-ocean ridges, and dense slabs sinking at trenches pull plates behind them.

Divergent boundaries widen oceans

Rifting opened the Atlantic after Pangaea broke up, and the Red Sea and East African Rift are forming the next ocean.

Convergent boundaries shrink oceans

Subduction at trenches like the Mariana Trench shrinks the Pacific, and the Tethys vanished when India met Eurasia.

Collision grows continents

Colliding crust thickens into the Himalaya and the Alps, while island arcs such as Japan add land.

Transform boundaries shift shape

Along the San Andreas Fault, plates slide past each other and redraw coastlines.

Hazard zoning

With about 59% of India's land prone to moderate or severe earthquakes (NDMA), IS 1893 seismic zoning must be enforced in building approvals.

Monitoring

The INCOIS tsunami warning centre (2007) and the Deep Ocean Mission (2021) should expand seismic and seabed monitoring.