Uncontrolled growth of settlement on hazardous hill slopes causing landslide?

landslides is a form of mass movement. an increase in shear stress and decrease in shear strenght will cause mass movement.

1) the weight of the houses alone will add shear stress to the earth beneath. leading to slope failure which can be landslides or any other kind of mass movement

2) settlements mean that there will be Plumbing. the underground pipes might leak and water plays major roles in landslides. firstly. water will lubricate rock layers. causing the soil to be unstable, decreasing shear strenght. the weight of water also adds to shear stress. and water also disolves the cohesive materials that keep soil particles together, decreasing shear strength. water will also increase in pore water pressure. that increases the shear stress.

3) if trees were cleared on the hill slopes to make way for settlements. this will also cause landslides. this is because trees like willows have roots that are water seeking. meaning they will dig deep down into the earth. holding the soil together. so removing the trees will mean a decrease in shear strength.