QUIZ 1. What are Earthquakes? 2. _____ is the deformation of a

material caused by stress. 3. Describe tension stress. 4. Faulting causes rock to _________ .

Answers 1. Vibrations of the earth’s crust caused by a

sudden release of energy

2. Strain

3. pulls apart

4. Break

Faulting

When stress exceeds the strength of the rocks

movement occurs along a weak region in the rock called

a fault

Movement along the fault results in EQ’s

Faults

Fault = any fracture or system of fractures along which the Earth

moves

Fault Plane = the surface along which the movement takes place

Example of Faulting • Cracks in the concrete • The crack represents strain resulting

from stress use by cars & people • The crack itself is a fault• The concrete surface where the fault

occurred is the fault planeThe type and direction of stress on the

concrete results in different types of faults

3 Types of Faults Normal = rocks are pulled apart;

Tension (stress) causing horizontal & vertical movement

p. 531 Table 19.1

3 Types of Faults Reverse or Thrust Faults =

rocks are forced together; Compression (stress) causing horizontal & vertical movement

p. 531 Table 19.1

3 Types of Faults Strike Slip = rocks are shearing,

twisting; Shear (stress) causing horizontal movement

p. 531 Table 19.1

Animation of Faults

• http://earthquake.usgs.gov/learning/animations/

• Reference USGS

Comparison between types of fault & plate boundaries

What type of fault is associated with converging plates?

• Reverse or Thrust Fault

What type of fault is associated with divergent

plates?

• Normal Fault

What type of fault is associated with transforming plates?

• Strike – Slip Fault

• Text read p. 530 – 532 • Quiz ?????

ANY QUESTIONS?