Causes and Effects of Earthquakes
Earthquake refers to the sudden violent movement of the earth’s crust. It creates seismic waves. It often causes great destruction. Its causes and effects are mentioned below.
Causes of Earthquakes
The important causes of the earthquake are:
Natural Causes of Earthquake:
- Tectonic Movement: This particularly happens when the continental plate collides against the oceanic plate. The oceanic plate is overridden by the continental plate. By a process called subduction jerky movements are caused along the inclined surface. Tectonic earthquakes have occurred in Assam in 1950.
- Volcanic Activity: Earthquakes may also be caused by the movement of lava beneath the surface of the earth during volcanic activity. The earthquakes due to Krakatoa volcanic eruption in 1883 is a good example of volcanic eruption.
- Dislocation of the Earth’s crust: Earthquakes may be caused by the dislocation of the crust beneath the surface of the Earth.
- Adjustment in inner Rock Beds: Earthquakes are also caused where is an adjustment between Sima [i.e., beneath the ocean is formed by Silica and Magnesium = Si + ma = Sima] and Sial (i.e., Continent is formed by Silica and Aluminium = Si + al = Sial) in the interior of the Earth’s Crust. This Earthquake may be called as a Plutonic Earthquake.
- Pressure of gases in the interior: The expansion and contraction of gases in the interior of the Earth sometimes cause a sudden shake on the Earth’s surface.
- Other Causes:
- Landslides and avalanches,
- Denudation of the Landmasses and depositions of materials,
- Faulting and folding in the rock beds are responsible for causing minor earthquakes.
- The impounding of large quantities of water behind dams disturbs the crustal balance. This causes earthquakes such as the Koyna earthquake in Maharashtra.
- The shock waves through rocks set up by the underground testing of Atom bombs or Hydrogen bombs may be severe to cause earthquake.
Effects of Earthquake
- Earthquake causes dismantling of buildings, bridge and other structures at or near epicenter. Many men and animals are killed or buried under collapsed houses.
- Rails are folded, underground wires broken. Fire breaks out inevitably in large towns.
- Earthquakes originate sea waves called Tsunamis.
- Earthquakes result in the formation of cracks and fissures on the ground formation.
- The earthquakes cause landslides and disturb the isostatic equilibrium.
- Landslide due to earthquake may block valleys to form lakes.
- Sometimes the earthquakes cause formation of hot springs which are very useful to people.
- The earthquakes sometimes cause submergence in coastal land, and result in formation of inlets, bays and gulfs which help to develop of fishing and shipping etc.
- Sometimes, the earthquakes cause emergence of costs and bring fertile shore out of water to give chance to develop crop production.
- The Circum-Pacific Mountain belt: About 70% of all earthquakes happen here. These cover islands areas of Japan, Philippines and Indonesia shaped like an arc. This belt is also known as the Pacific Ring of Fire.
- The Mid-World Mountain Belt: About 20%, of all earthquakes occur in this belt covering parts of Europe and Asia.
- Other Belts: Remaining 10% are scattered in 0-700 km range over ocean floor, rift valleys and other areas.
Natural disasters happen all over the world, and they can be utterly devastating for people’s lives and the environments in which they live. Although natural disasters are caused by nature and there is nothing that we can do to prevent them happening, there are many different natural causes that lead to natural disasters, and being aware of these causes enables us to be better prepared when such disasters do arrive.
One common natural disaster is flooding, which occurs when a river bursts its banks and the water spills out onto the floodplain. This is far more likely to happen when there is a great deal of heavy rain, so during very wet periods, flood warnings are often put in place. There are other risk factors for flooding too: steep-sided channels cause fast surface run-off, while a lack of vegetation or woodland to both break the flow of water and drink the water means that there is little to slow the floodwater down. Drainage basins of impermeable rock also cause the water to run faster over the surface.
Earthquakes are another common natural disaster that can cause many fatalities. The movements of the plates in the earth’s crust cause them. These plates do not always move smoothly and can get stuck, causing a build-up of pressure. It is when this pressure is released that an earthquake occurs. In turn, an earthquake under the water can also cause a tsunami, as the quake causes great waves by pushing large volumes of water to the surface.
Tsunamis can also be caused by underwater volcanic eruptions. Volcanic eruptions are another natural disaster, and they are caused by magma escaping from inside the earth. An explosion takes place, releasing the magma from a confined space, which is why there are often also huge quantities of gas and dust released during a volcanic eruption. The magma travels up the inside of the volcano, and pours out over the surrounding area as lava.
One of the most common natural disasters, but also one of the most commonly forgotten, is wildfires. These take place in many different countries all over the world, particularly during the summer months, and can be caused by a range of different things. Some of the things that can start the wildfires can be totally natural, while others can be manmade, but the speed at which they spread is entirely down to nature. The two natural causes of wildfires are the sun’s heat and lightning strikes, while they can also be caused by campfires, smoking, fireworks and many other things. The reasons that they spread so quickly are prolonged hot, dry weather, where the vegetation dries out, which is why they often take place in woodland.