What an earthquake fault looks like:

Above is a small earthqake fault in cross section along a roadside in Canadas Yukon Territory The block on the left has fallen several feet relative toi the block on the right.  The matching dark sedimentary beds are all the evidence one needs to find the fault. The fault slopes from the upper right to lower left in this picture.  There is a secondary fault farther to the left.

This is a thrust fault and it pushed the rock on the left up about 20 feet in what must have been a mammoth eartquake in western Utah. Desert environments preserve fault scarps such as these for long periods of time