Very small slip circle

This effect is typical for slip circles with soils of cohesion = 0.

If the soil really had a cohesion of 0, only a small mass of soil would slide down at the surface of the slope.

But any soil has at least a small "apparent cohesion". When entering a value of only 0.5 or 1.0 for the cohesion there is a much better result for the slip circle.