Earthquakes

Earthquakes

SCI/245 Geology (Axia)

October 2, 2011

Earthquakes

The Earth has plates. Plates move, we do not see them move, and there are times that they collide. When this happens, we usually hear that there has been an earthquake. In this paper the subject to address is how plate boundaries move, along with the types of plate boundaries, and explain what an earthquake is.

The lithosphere is composed of the crust and the uppermost part of the mantle and is the outermost shell of the Earth. “The outermost shell of the Earth is about 100 km thick” (Murck, 2008, p. 141). The lithosphere is made up of seven main plates and several smaller plates. Earth’s seismic and volcanic activity happens when these plates meet. They meet at boundaries or plate margins.

Divergent is the first plate boundary. Divergent means “a boundary along which two plates move apart from one another (Murck, 2008, p. 104). When the plates move apart from one another, new crust is created. Earthquakes at mid-ocean ridges are shallow and reveal that plates are moving apart.

Convergent boundary is the second boundary type. Convergent means, “a boundary along which two plates come together” (Murck, 2008, p. 104). This depends on whether it is two oceanic plates or two continental plates. This would be mountains and volcanoes are found as recycled crust.

Transform fault boundary is the third boundary type. Transform fault means, “a fracture in the lithosphere where two plates slide past each other” (Murck, 2008, p. 104). With this the two plates slide past each other horizontally. This creates faults. The transform faults are usually found on the ocean floor; however, some can be found on land.

When there is differential movement along the plates, usually an earthquake occurs. When the plates move they are usually rough. This is when the stress builds up and there is strain in the plates. The strain cannot be stored. The rocks move past each other. An earthquake will happen when the...