Earthquakes are the sudden movement caused under the ground. This is caused mainly due to the movement of seismic waves through the rocks of the earth. This movement is caused when the earth’s stored energy is released suddenly within the earth’s surface.
Earthquakes occur usually in narrow areas where large rocks move along one another. Little was known about this until seismology emerged during the beginning of the 20th century. Seismology is the study of earthquakes. This has helped in answering different questions about the occurrence of an earthquake.
Nature of this phenomenon
Earthquakes occur about 50,000 times in the entire world in a year. These are known to be long-lasting. Out of these about 100 are sufficient to cause huge danger and damage to mankind. Very great earthquakes occur once in a year which is the main reason for the death of several lives and destruction of property.
Causes of Earthquake
The major earthquakes of the earth occur mainly in those belts which coincide with tectonic plate’s margin. When there is a continuous motion of the tectonic plates, it leads to a steady building of pressure. This pressure occurs on the rock strata on both sides of the fault.
It continues until the pressure is great enough to be released in a jerky and sudden movement. The wave which is caused inside the ground causes the land surface to shake. Thus we perceive them as earthquakes.
Different types of earthquake.
The earthquakes which are caused by the tectonic plates are known as tectonic quakes. They are the reason behind most earthquakes and usually take place at the boundary of (plates) tectonic.
Volcanic earthquakes are caused due to volcanic eruptions or are associated with volcanism. These earthquakes occur near the surface and are less powerful than tectonic quakes. Thus, they are felt in and around the vicinity of the hypocenter.
Earthquakes are caused sometimes due to human activities, injection of some sort of fluids in the walls, some underground explosions, and filling of some reservoirs. Large nuclear explosions are known to produce slips in the vicinity of test devices.
The earthquakes which are caused by the activities of human being or mankind are called induced earthquakes. They must be the reasons for filling reservoirs, implementation of geothermal projects, implementation of fracking projects and construction of a tunnel.
These are small earthquakes which occur under the ground or in mines due to an explosion of rocks over the surface. The roof of the mines usually gets shaken due to sudden earthquakes. Some certainly occurred events of collapse earthquakes is also known as mine burst.
Some effects of the earthquake.
Earthquakes have severe effects like the destruction of human and animal life, changes in the geographic features and damage to artificial manmade structures. These generally affect the land surface. But as the plates are present below the earth, the ocean margins are also affected.
Earthquakes often lead to the occurrence of drastic geographical changes including vertical and horizontal ground movements, rising of the surface, dropping off the surface, landslides, change in the flow of groundwater, mudflow, and tilting of the surface.
Occurrence of earthquakes
The seismicity pattern did not have any concrete definition (theoretical). It became clear to people after the model of plate tectonics was invented. This theory gives a description in which the lithosphere (upper or outer shell of the earth) consists of a number of plates.
The low-level waves moving through the plates leads to the occurrence of small and large earthquakes. However, the description of the wave can be given using tectonic mechanism.
Prediction of Earthquakes
Observation and prediction of the phenomenon:
The research for earthquakes periodic cycle has been an old issue. One of the problems is the occurrence of the earthquake. Those are not homogeneous in reporting and selection. Statistical quakes have also been tried with a population of earthquake-prone areas.
Measures of reducing hazards of earthquake
Continuous work has taken place in seismology for explaining the characteristics of the moving waves. The sounds are recorded and afterward examined. Even though the destruction of life and property is caused by some after earthquake phenomena like landslide and tsunami, the major population faces danger due to the collapsing of structures which are manmade. To solve this problem, constructions must take place which will be able to withstand the pressure of the earthquakes.