Common Factors Cause Of Landslides, Know Before It's Too Late

Landslide material piled up residential areas in Cihanjuang Village, Cimanggung District, Sumedang Regency, January 2021 (Bagus Ahmad Rizaldi / Antara)

JAKARTA - Indonesia is a country that often occurs landslides almost every year. Landslides are the displacement of slope-forming material in the form of rock, scrap material, soil, or mixed material, moving down or out of the slope.

As reported from esdm.go.id, the way landslides occur can be described as follows: water that absorbs into the soil will increase the soil load. If the water penetrates until the ground is impermeable, which acts as a sliding area, then the soil becomes slippery and the weathering soil above it will move along the slope and out of the slope.

Then what are the factors that cause the landslide process?

In principle, landslides occur when the supporting force on the slope is greater than the blocking force. The blocking force is usually influenced by rock energy and soil density. Although the supporting force is influenced by the magnitude of the slope angle, water, load and weight of the rock soil variability.

The general factors that influence it are:

Rain

Heavy rain at the beginning of the season can cause landslides, because through the soil that breaks the water will enter and accumulate in the base components of the slope, causing lateral movement. If there are trees on the surface, landslides can be prevented because the water will be absorbed by the plants. Plant roots will also bind the soil.

Steep Slopes

A steep slope or cliff will increase the supporting force. Steep slopes are formed due to erosion of rivers, springs, sea water and wind. Most of the slope angles that cause landslides are 180 if the tip of the slope is steep and the area of the landslide is horizontal.

Less dense and thick soil

The less dense soil type is clay or clay with a thickness of more than 2.5 m and a slope angle of more than 220. This type of soil has the potential for landslides, especially if it rains. Apart from that this soil is really susceptible to soil movement because it becomes soggy with water and breaks when it gets too hot.

Less strong rocks

Volcanic sediment and sedimentary rock the size of sand and a mixture of gravel, sand and clay is usually less strong. These rocks will easily become ground if subjected to a weathering process and are usually vulnerable to landslides if they are on a steep slope.

Old Avalanche Former

Old landslides usually occur during and after the deposition of volcanic material on relatively steep slopes or during or after a break in the earth's crust. Old landslide scars have the following characteristics:

There is a long curved steep cliff that makes a horseshoe. Usually found in springs, trees that are relatively thick because the soil is loose and fertile. The place of the upper component landslide body is usually relatively gentle. Small landslides were encountered, especially on cliffs. There are relatively steep cliffs which are the former of small landslides in old landslides. There are ravines and small cracks and landslides on the cliffs. This old avalanche was quite extensive.