Evaluate how plate tectonics theory helps our understanding of the distribution of seismic and volcanic events(40)
The global seismic and volcanic activity is concentrated along the margins of the earth’s plates, which are broken pieces of the crust and are moved by convection currents that are caused by heat rising and falling inside the mantle generated by radioactive decay in the core. This movement of the plates and the Earth’s inner activity is called plate tectonics and can cause seismic and volcanic activity. However, earthquakes and volcanoes also occur within the plates rather than their edges, an example of which is the Hawaiian volcanoes that occur above a stationary hot spot beneath the Pacific plate. In the late 1960s the theory of plate tectonics was developed by Alfred Wegener and provides an explanation for the Earths tectonic behaviour, particularly the global distribution of mountain building, earthquake activity, and volcanism in a series of linear belts. However, before the theory was developed people had noticed that the continents either side of the Atlantic Ocean seemed to nearly fit together. In 1912 Alfred Wegner published the theory of continental drift suggesting that the continents used to be joined together in an ancient supercontinent which he named Pangaea. He then proposed that it later split in to two continents- Laurasia in the north and Gondwanaland in the south, which further split forming our current continents and at some point these land masses had drifted apart to their current positions on the globe. The evidence for his theory that the continents were once joined includes continental fit where some continents seem to fit together if they were placed next to each other. This is particularly true if the continental shelves are taken into account as the edges of the land masses. Moreover, there is geological evidence where rocks of the same type and age that display the same formation have been found in South-East Brazil...
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