If you draw a line through the center of a diagonal stair-step crack, then draw a perpendicular arrow to it, you will have the approximate direction of movement—either up or down—of the crack. Many cracks have a “hinge point” at one end and loosely pivot around that point, with the opposite end being wider. Others move more uniformly.
This crack pattern usually indicates settlement of the corner of a structure (blue arrows). The corner of the house is “laying down,” like the severe example shown below. But it can also indicate heaving of the area to the left of the crack (green arrows), and sometimes requires close examination to determine which side is moving.
A pyramid shaped crack of joined diagonals, as in the diagram below, is usually indicative of subsidence (dropping) of the area under the pyramid. Because window openings are weak spots when a wall is having settlement or heaving problems, diagonal cracks emanating from the corner of a window are common.