What is does creep?

Creep is a phenomenom of a sample to deform against time at particular temperature. Creep is the tendency of a solid material to slowly move or deform permanently under the influence of stresses....

creep is term used for failure of materials under constant load at elevated temperatures. Eg: lathe bed.

creep resistance is a slow down in the speed of dislocations within a crystal structure

It can be caused by GRAVITY as in the case of old lead pipe sagging. In addition copper contact wires in electrified transport systems sagging under permanent stress causes creep.

Tectonic creep is the almost constant movement of certain fault blocks that allows strain energy to be released without causing major earthquakes.