Causes:Earthquakes are usually caused when rock underground suddenly breaks along a fault. This sudden release of energy causes the seismic waves that make the ground shake. When two blocks of rock or two plates are rubbing against each other, they stick a little. They don't just slide smoothly; the rocks catch on each other.
Where are earthquakelikelyto occur:Earthquakes occur all the time all over the world, both along plate edges and along faults. Most earthquakes occur along the edge of the oceanic and continental plates. The earth's crust (the outer layer of the planet) is made up of several pieces, called plates.
NORMAL FAULT
description:a dip-slip fault in which the block above the fault has moved downward relative to the block below. This type of faulting occurs in response to extension and is often observed in the Western United States Basin and Range Province and along oceanic ridge systems.
Type of Stress: tensional stress
Type of boundaries:Divergent Plate Boundary
What is happening:A geologic fault which the hanging wall has moved downward relative to the footwall. Normal Faults occur when two blocks of rock are pulled away by tension. They are associated with divergent Boundaries.
REVERSEFAULT
Description:A reverse fault is the opposite of a normal fault—the hanging wall moves up relative to the footwall. Reverse faults indicate compressive shortening of the crust.
Type of Stress:Compressive Stress
Type of boundaries:Convergent Plate Boundary
What is happening:In a reverse fault, the block above the fault moves up relative to the block below the fault. This fault motion is caused by compressional forces and results in shortening.
STRIKE-SLIP FAULT
Description:Strike-slip fault, also called transcurrent fault, wrench fault, or lateral fault, in geology, a fracture in the rocks of Earth's crust in which the rock masses slip past one another parallel to the strike, the intersection of a rock surface with the surface or another horizontal plane.
Type of Stress:Shear Stress/ Shearing
Type of boundaries:Transform Plate Boundary
What is happening:a fault on which the two blocks slide past one another. The San Andreas Fault is an example of a right lateral fault.
Answers & Comments
Causes: Earthquakes are usually caused when rock underground suddenly breaks along a fault. This sudden release of energy causes the seismic waves that make the ground shake. When two blocks of rock or two plates are rubbing against each other, they stick a little. They don't just slide smoothly; the rocks catch on each other.
Where are earthquake likely to occur: Earthquakes occur all the time all over the world, both along plate edges and along faults. Most earthquakes occur along the edge of the oceanic and continental plates. The earth's crust (the outer layer of the planet) is made up of several pieces, called plates.
NORMAL FAULT
description: a dip-slip fault in which the block above the fault has moved downward relative to the block below. This type of faulting occurs in response to extension and is often observed in the Western United States Basin and Range Province and along oceanic ridge systems.
Type of Stress: tensional stress
Type of boundaries: Divergent Plate Boundary
What is happening: A geologic fault which the hanging wall has moved downward relative to the footwall. Normal Faults occur when two blocks of rock are pulled away by tension. They are associated with divergent Boundaries.
REVERSE FAULT
Description: A reverse fault is the opposite of a normal fault—the hanging wall moves up relative to the footwall. Reverse faults indicate compressive shortening of the crust.
Type of Stress: Compressive Stress
Type of boundaries: Convergent Plate Boundary
What is happening: In a reverse fault, the block above the fault moves up relative to the block below the fault. This fault motion is caused by compressional forces and results in shortening.
STRIKE-SLIP FAULT
Description: Strike-slip fault, also called transcurrent fault, wrench fault, or lateral fault, in geology, a fracture in the rocks of Earth's crust in which the rock masses slip past one another parallel to the strike, the intersection of a rock surface with the surface or another horizontal plane.
Type of Stress: Shear Stress/ Shearing
Type of boundaries: Transform Plate Boundary
What is happening: a fault on which the two blocks slide past one another. The San Andreas Fault is an example of a right lateral fault.