Faults

Types of Faults and How Earthquakes Occur **By: Yoosub & Taing Taing 7B **

**__ Types of Faults __**

A fault is a thin zone of crushed rock between two blocks of rock. They can be any length; mere centimeters or thousands of kilometers. A fault is a fracture in the crust of the earth when rocks on one side have moved according to those on the other. Most of the faults are results of repeated displacements over periods of time. Mainly there are about 3 kinds of faults. But if you look carefully there are at least 5 of them. The 5 different Faults are:
 * Normal Fault
 * Reverse Fault
 * Strike-Slip Fault
 * Thrust Fault
 * Right Lateral Strike-Slip Fault

A Normal Fault is a dip-slip fault which means vertical displacement that occurs. The Reverse Fault occur the place where two blocks of rocks are forcing it by pressure. When the fault plane is slanted at an angle equal or less than 45 ° then it's reverse fault. A strike-slip fault that's block on opposite fault plane from fixed spots that have move to the right place. A thrust fault is break in the Earth's crust across which is the relative movement. The right-lateral strike-slip fault motion are also known as the dextral faults.

How Earthquakes Occur __**
 * __

Earthquakes are caused by faults and they are vibrations produced by the breakings of rocks. They can be unnoticeable vibrations or devastating waves of energy. Earthquakes result from rocks moving over, under, or past each other along fault surfaces. When rocks move past each other along a fault, it is the beginning of an earthquake. The rough surfaces catch for a while halting the movement along the fault. But the forces of earth keeps the rocks moving and that builds up stress at points where they are stuck. The stress makes the rocks bend and change shape. When rocks are beyond their elastic limit, they break, move along the fault, and then return to their original shapes they had before. That is when an earthquakes happens. Earthquakes happen when two tectonic plates move against each other. The rocks break underground mostly at the hypocenter and the earth begins to shake. The waves spread from the epicenter which is the point of the surface above the hypocenter. If a quake occurs under the sea, it is called a tsunami. Instead of causing the earth to break, when a tsunami happens it cause huge waves. When an earthquake happens on a normal, reverse, or strike slip fault, the rock on one side of the fault slips towards the other. The surface of the fault can be vertical, horizontal, or an angle to the surface of earth. The direction of the slip can be at any length too and because of this there can be two different types of earthquakes; the strike-slip fault earthquake and the dip slip earthquake.

**Bibliography** [|www.crew.org] [|www.fema.gov] [|http://news.bbc.co.uk] [] [|http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/tectonics_landforms/faulting_p2.html] [] [] [] Glencoe Science Earth Science National Geographic Textbook **Images Cites** [|www.uh.edu/~jbutler/physical/chapter18.html] [|www.fareastgizmos.com] [|www.knowledgerush.com] []