GEOLOGY

Detailed explanation-1: -Rainfall-Prolonged or intense rainfall and rain-on-snow events can saturate soils and trigger landslides. Earthquakes-Intense shaking during earthquakes can cause the ground to fail. The earthquakes of 1949, 1965, and the Nisqually earthquake of 2001 produced numerous landslides throughout the Puget Sound region.

Detailed explanation-2: -Landslides are caused due to three major factors: geology, morphology, and human activity.

Detailed explanation-3: -Although gravity acting on an over-steepened slope is the primary reason for a landslide, there are other contributing factors: erosion by rivers, glaciers, or ocean waves create oversteepened slopes. rock and soil slopes are weakened through saturation by snowmelt or heavy rains.

Detailed explanation-4: -A landslide occurs because the force of gravity becomes greater than either friction or the internal strength of the rock, soil, or sediment. The amount of friction between a deposit of rock or soil and the slope that it rests on plays a large role in when landslides happen.