Landslides are caused by disturbances in the natural stability of a slope. They can accompany heavy rains or follow droughts, earthquakes, or volcanic eruptions. Mudslides develop when water rapidly accumulates in the ground and results in a surge of water-saturated rock, earth, and debris.

Slope The steep sides of mountains and hills make water flow down them faster. Fast-moving water has more energy to break down rock than slow-moving water. Therefore, rocks on steep slopes can weather faster than rocks on level ground.

The build-up to a landslide is as important as the trigger event, as: weathering along rock face fissures will reduce the rock’s strength – a trigger mechanism can then overload the slope and make it fail. susceptible rock or sediment must be present.

There are two main types of erosion: chemical and physical. In physical erosion, the rock breaks down but its chemical composition remains the same, such as during a landslide or bioerosion, when plants take root and crack rocks.

The impact of a landslide can be extensive, including loss of life, destruction of infrastructure, damage to land and loss of natural resources. Landslide material can also block rivers and increase the risk of floods.

The two regions most vulnerable to landslides are the Himalayas and the Western Ghats. The Himalayas mountain belt comprise of tectonically unstable younger geological formations subjected to severe seismic activity.

The term “landslide” encompasses five modes of slope movement: falls, topples, slides, spreads, and flows. These are further subdivided by the type of geologic material (bedrock, debris, or earth). Debris flows (commonly referred to as mudflows or mudslides) and rock falls are examples of common landslide types.

The Appalachian Mountains, the Rocky Mountains and the Pacific Coastal Ranges and some parts of Alaska and Hawaii have severe landslide problems. Any area composed of very weak or fractured materials resting on a steep slope can and will likely experience landslides.

On September 20, 2018, a landslide caused by heavy rainfall and quarrying operations by Apo Land and Quarry Corporations (ALQC) in Naga, Cebu, Philippines, killed 78 people.

Based on Department of Environment and Natural Resources, Mines and Geo-Science Bureau (DENR0MGB) had listed top 10 landslides prone provinces such as Benguet, Mountain Province, Nueve Vizcaya, Kalinga Apayao, Southern Leyte, Abra, Marinduque, Cebu, Catanduanes, and Ifugao.

On the night of August 3, 1999, a massive landslide occurred in Cherry Hills subdivision in Antipolo, Rizal province, Philippines that resulted to about 60 death toll and 378 houses buried. The landslide was primarily caused by the heavy rains of the approaching typhoon Olga.