Landslides don't occur at a specific boundary in the traditional sense. They happen when the slope of the land becomes unstable, leading to a mass movement of soil, rock, or debris. This instability can arise from a combination of factors, including:

* Geological factors:

* Slope angle: Steeper slopes are more prone to landslides.

* Rock type: Weak or fractured rocks are more susceptible.

* Soil type: Loose or saturated soil is more likely to slide.

* Triggering events:

* Rainfall: Heavy rains saturate the soil, increasing its weight and reducing its strength.

* Earthquakes: Seismic vibrations can shake loose soil and rock.

* Human activities: Construction, deforestation, and mining can alter slopes and trigger landslides.

Therefore, a landslide occurs at the boundary between a stable slope and an unstable one. This boundary is often marked by a change in the slope angle, the presence of a weak layer, or the saturation of the soil.

It's important to note that landslides can occur in a variety of settings, from steep mountain slopes to gentle hillsides. The specific factors that contribute to a landslide will vary depending on the location and the underlying geology.