Volcanic and Seismic Events as Proof of Plate Tectonic Theory

2657 Words Sep 26th, 2013 11 Pages
Volcanic and Seismic events are major pieces of evidence towards proving that plate tectonics theory is valid.
A seismic event is the transient motion and release of kinetic energy caused by sudden failure of the earth's crust, usually felt as shaking or tremors in the rock mass. Seismic events range in size from barely perceptible tremors to major earthquakes. Volcanic events occur when there is a release of magma, gas and ash from the Earth’s crust.
The entire outer surface of the planet is divided into these plate formations with approximately 30 in total. These different plates vary in size from over 100,000,000 square miles, for example The Pacific Plate, to the Galapagos micro plate at 12,000 square miles. Fault lines separate each
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Some surface waves (Raleigh waves) shake the ground at right angles to the direction of wave movement and some have rolling motion that produces vertical ground movement.
Modern understanding of the structure of Earth is derived in large part from the interpretation of seismic studies that measure the reflection of seismic waves off features in Earth's interior. There are many types of seismic waves released by the rupture of rocks at the focus. Different materials transmit and reflect seismic shock waves in different ways, and of particular importance to the theory of plate tectonics is the fact that liquid does not transmit S-wave. This is because the mantle transmits S-waves, it was long thought to be a cooling solid mass. Geologists later discovered that radioactive decay provided a heat source within Earth's interior that made the asthenosphere plasticine (semi-solid). Although solid-like with regard to transmission of seismic S-waves, the asthenosphere contains very low velocity (inches per year) currents of magma-like molten materials.
They are more destructive due to subduction zones or compression forces along the Benioff Zone. The Benioff Zone is a sloping plane where two plates ride over one another. The friction created will produce earthquakes, and heat which will destroy the two plates. At (continental-continental) destructive plate margins, shallow focus earthquakes occur over a broad

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