Faults are fractures that allow blocks on either side to move with respect to each other.  The three movies below show three kinds of movement. Click and drag each movie to see the type of movement involved and read the important description below that movie. 

Offset fault 

Blocks can move up or down with respect to each other.  Such faults are called dip-slip faults, because movement is up or down the dip (slope) of the fault.

Blocks can move laterally (side to side) with respect to each other.  Such faults are called strike-slip faults, because movement is parallel to the strike (a horizontal line) of the fault.

Blocks can move with a combination of up or down and side to side.  Such faults are called oblique-slip faults, because movement is oblique (at an angle) to both the strike and dip.

Types of Faults Start Page