Landslides: All you need to know

Natural disasters are coming more intensely and more frequently every year. The least we can do is to have a good, clear knowledge of what they are, why they occur and how to prevent them. So, here’s Landslides 101 for you.

You can see how, just above this area, there are no trees.

Landslides are any mass movement of earth material along a definite slope/surface/zone, under the action of gravity. While landslides are classified into many different types, there are some that you should know of.

  1. Slump- this is the classic landslide, where you have a mass of material moving down a slope because they slipped, and pile up at the bottom of the slope.
  2. Rock falls- When weak rocks are present along a steep slope, there is a high chance that they may be dislodged and will crash down to the bottom faster than you can say “Rock fall”.

These two account for almost all of the landslide related accidents all over the world.

So, why do they occur? Here are the top reasons-

  1. Many of the landslides are related to human activities. This includes cutting through hills/mountainsides to build roads, rail roads or tunnels. It dislodges the rock, makes it structurally weak and extremely susceptible to a landslide.
  2. Groundwater is a major cause, because water has a tendency to flow along weak planes of a rock mass, lubricating it and making it weaker. It can also dissolve parts of the rock, and making it highly likely that they will dislodge and fall off.
  3. Landslides always occur if there is an earthquake that happened in the vicinity. The tremors shake and dislodge rocks and cause the slope to fail.
  4. Another big cause of landslides is deforestation above the slope. This makes water flow down the slope easily, and it can carry off a huge load of sediments along the slope. You kind of have a landslide and flood rolled into one, in this case.
This looks like it happened because of an earthquake.

Other causes do exist, but these are the ones you really need to watch out for.

There are, of course, things we can do to prevent the destruction caused by these landslides. It may not be possible to predict when a landslide will happen, but it is possible to demarcate where it is likely to happen, and appropriate measures can be taken.

  1. Grow trees up slope. This will slow down the flow of water, and the roots of the trees bind weak soil together and make it less likely to dislodge.
  2. If there is a lot of groundwater flowing in the area, it’s best to draw it out through wells or tube wells around the sleep, thereby diverting the flow away from the weak slope. Without water, rocks tend to stick together more cohesively.
  3. When building roads/railroads, make sure you are cutting across strong rock that will not fall easily. It will also help if you can add some extra support, by building walls or putting nets across the slope.
  4. What can you do as a normal person? If you live in such a place, make your roofs strong and sloped, so any material that falls will slide off without causing too much damage. Use groundwater as much as possible, and make sure you have planted a lot of trees.

Even if you don’t live in such a place, it’s possible you will encounter the risk of a landslide when you are travelling in the hills. Keep your eye out, and run if something is about to happen. You can also inform the authorities so proper measures can be taken by them to keep roads safe.

Hope this helped!


 

All pictures from Google Images.

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