The idea of tectonic plates was put forward by Alfred Wegener early last century. He noticed that the coastline of South America fits to that of Africa.
More than that he found that:
Other scientist did not believe his theory as he could not explain how the two continents could have moved apart. We now use Wegener's theory to explain mountain formation, but that was not always the case.
Since Wegner's death further evidence has been discovered such as:
From Google Maps
We now know that the Earth's crust and the upper part of the mantle are cracked into a number of large pieces called plates.
This causes currents within the Earth's mantle which in turn cause the plates to move in a process known as crustal movement or continental drift. This is at average relative speeds of a few per year.
The movements can be sudden and disastrous. They can cause and/or eruptions at the boundaries between tectonic plates. If plates are moving relative to each other they can become stuck when there will be a build up of strain. This may in a number of smaller quakes or result in a large one. Scientists find it difficult to the exact time of earthquakes. The best that can be done at the moment is to look at the time between quakes and apply that to the future.
Scientists find it difficult to the exact time of earthquakes. The best that can be done at the moment is to look at the time between quakes and apply that to the future.
