In: Civil Engineering
The Theory of Plate tectonics deals with the dynamic behaviour of the outer shell of earth called the lithosphere. Providing uniform content for understanding earthquakes, land shift, volcanoes, mountain building as well as the reconstruction of its surface.
Earth's outer layer is made up of rigid surface, whose approximately depth or thickness is about 110 km and just below which is overlies a molten layer known as the asthenosphere. These plates are broken up mainly or majorly into seven plates containing continents and oceans, about 6-7 medium-sized and many small ones. These plates converge, diverge or slip depends on their relative motion to each other at a speed of 50-100 mm per year. The interaction between these plates is the reason for earthquakes, tsunami, faults, volcanic activities on earth crust.
The geography we see today of our Earth's crust is because of the movement of plates but the reason behind their movement lies under the asthenosphere which is still in debate and hasn't been confirmed