What does the factor of safety measure in geological terms?

The factor of safety is a crucial concept in geotechnical engineering and stability analysis. It measures the stability of a slope by comparing the forces acting to cause failure (such as gravity) against the forces resisting failure (such as friction and cohesion). A factor of safety greater than one indicates that the slope is stable and the resisting forces are greater than the driving forces, while a factor of safety less than one suggests that the slope may fail.

In the context of slope stability, the factor of safety incorporates various parameters, including soil strength, slope angle, and water conditions, to determine how likely a slope is to maintain its condition without failure. This makes it an essential parameter in geological assessments, particularly when evaluating potential landslide risks or designing structures on or near slopes.