Discuss the Degree to Which the Theory of Plate Tectonics Is Supported by the Distribution of Seismic Activity Across the Globe.

Topics: Plate tectonics, Mid-ocean ridge, Seafloor spreading Pages: 3 (942 words) Published: April 7, 2013
Plate tectonic theory is a widely excepted theory that the Earth’s lithosphere is made up of plates, both oceanic and continental, which slowly move due to convection currents in the mantle and the asthenosphere. However, it is very hard to be certain as we can’t see the structure of the Earth, so some people do not agree with it. This theory saw the introduction of what we know today to be tectonic plates. Tectonic plates occur where there is radioactive decay in the core and temperatures are extremely high. This decay can occur anywhere in the earth’s core. This results in a plume of magma rising through the mantle creating a thermal current. When this current reaches the surface it spreads through the asthenosphere, before cooling and sinking. These are the convection currents which move tectonic plates. Convection currents will only occur in liquid form and in warm conditions. Tectonic plate theory has evidence to prove that these currents do take place. We know that the mantle is liquid and has high temperatures as magma that originates in the mantle is molten. This means that convection currents can occur. This part of plate tectonic theory is supported by global seismic activity because if convection current did not exist and plates were not able to move, earthquakes would not occur at any plate boundaries, but particularly at collision plate boundaries as there would be no plate movement. Another part of tectonic theory, which came before the suggestion of plates, is palaeomagnetism which was first discovered in the 1960s. It was suggested that approximately 400,000 years the Earth experienced reverse polarity. This means that the magnetic north and south poles swap direction. This was backed up by evidence which involved ferrous rich rocks such as magnetite under the Atlantic Ocean. These rocks are found on the sea floor on either side of the Mid-Atlantic Ridge and are formed when solidified magma broke through the lithosphere at the Mid-Atlantic Ridge...
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