What is a crack or opening of the earth's crust?

Answer 1

In geological terms, a crack or fracture in the earth's surface is a fault (as in the San Andreas Fault).

Answer 2

A crack or opening in the Earth's crust is known as a fault. Faults are caused by tectonic forces that create stress and movement along the plates, resulting in fractures in the Earth's crust. Movement along faults can cause earthquakes.

Answer 3

it is a fault. that's like two plates moving apart from another aka an earth quake(plate tectonic) it also causes a rift valley to form and can turn into a lake and some times an ocean.