The type of fault that occurs when one or both portions of rock move in a horizontal direction is called a strike-slip fault.

Here's a breakdown:

* Strike: The strike of a fault is the direction of the line of intersection between the fault plane and a horizontal surface.

* Dip: The dip of a fault is the angle between the fault plane and the horizontal plane.

* Strike-slip Fault: In a strike-slip fault, the movement is primarily along the strike of the fault. This means the blocks of rock slide past each other horizontally.

There are two types of strike-slip faults:

* Right-lateral: When looking across the fault, the opposite side moves to the right.

* Left-lateral: When looking across the fault, the opposite side moves to the left.

Examples of strike-slip faults:

* San Andreas Fault (California): A right-lateral strike-slip fault responsible for major earthquakes.

* North Anatolian Fault (Turkey): A right-lateral strike-slip fault responsible for numerous earthquakes.

Let me know if you have any other questions!