Waves And Plates Tectonics

1. Waves And Plates Tectonics

2. How The Theory Came About • Plate tectonics is a scientific theory which describes the large scale motions of Earth's lithosphere. It is vital for the existence of life on earth because of the role that it plays in the global cycle that maintains the balance of carbon between the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere. A similar process likely takes place on other celestial objects when they are sufficiently similar to Earth. The theory builds on the older concepts of continental drift, developed during the first decades of the 20th century by Alfred Wegener, and seafloor spreading, developed in the 1960s.

3. Evidence • If you look at a map, Africa seems to snuggle nicely into the east coast of South America and the Caribbean sea. In 1912 a German Scientist called Alfred Wegener proposed that these two continents were once joined together then somehow drifted apart.  He proposed that all the continents were once stuck together as one big land mass called Pangea. He believed that Pangea was intact until about 200 million years ago

4. Plate boundaries

5. Volcanoes • Volcanoes are formed usually near plate boundaries, most commonly convergent/destructive plate boundaries, such as the Pacific Ring of Fire, which contains about 68% of Earth's volcanoes. A volcano is formed when there are cracks in the plates. When a denser plate, such as the oceanic plate, subducts under another plate, either a continental or oceanic plate, the subducted plate will melt under extreme temperatures in the mantle. This will form cracks in the plates, which results in magma flowing out from the mantle through the cracks in the plate and out onto Earth's surface.

6. What Causes Earthquakes? • Firstly, they can be linked to explosive volcanic eruptions; they are in fact very common in areas of volcanic activity where they either proceed or accompany eruptions. • Secondly, they can be triggered by Tectonic activity associated with plate margins and faults. The majority of earthquakes world wide are of this type.

7. How To Find The Epicenter? • You need to find the difference between the arrival times of P and S waves. From there three or more stations put their results and data together and make circles of distance with a chart. When all three of them cross at a point that is roughly where the epicenter is.