Questions as to what is the power behind this destruction have developed in the minds of early man which resulted in several myths and mysteries. Finally, in the twentieth century, the plate tectonic theory emerged as an explanation to these earthquakes and volcanoes. Geologists studied the Earth and concluded that it was covered by a solid rock crust from outside, whereas the inner crust contained metals and the innermost was a composition of hot liquid part known as the mantle. When volcanoes erupt, this hot part comes out in the form of lava.
Plate Tectonic Theory:
Scientists believe that all the land located on the Earth was once joined into a large mass. Eventually with time, these continents drifted apart and oceans were formed between them. However, this drifting has not stopped although the land is moving apart at a very slow pace. The truth for this drift is hidden behind the depth and darkness of the oceans. Basically, the entire earth is made up of tectonic plates which are in constant motion. This movement of the plates causes the earthquake, volcanic and other destructive activities to occur. However, plate movement is caused by the happenings taking place inside the Earths crust, near the core. The two major effects caused by the movement of tectonic plates which harm the human life is earthquake and volcanoes. These consequences are devastating which can wipe out a whole region affecting the established and developed lives.
These processes occur at the edges of the plates where two or more of them meet. The movement of convection currents in earth causes three different types of plate boundaries, depending on the movement of the plates which are as follows:
· Divergent (constructive) Boundary
· Convergent (destructive) Boundary
· Transform (conservative) Boundary
Such boundaries result hen the plates move apart due to the molten rock or the magma which rises from the mantle of the Earth. It solidifies when reaching the Earths surface, forming a crust. Thus, mid-ocean ridges are formed which are underwater mountains. These are formed by the magma which fills the gap created by the divergent plates. Hence the cooled magma attaches itself to the plates. This process is known as sea floor spreading.
A convergent boundary is an area where tectonic plates move towards one another and collide. As a result, a subduction zone or a continental collision is formed depending upon the nature of the plates in action. In this boundary, the crust is formed again as one plate moves under the othe.
The types of convergent boundaries is as follows:
· Oceanic-Continental Convergence
· Oceanic-Oceanic Convergence
· Continental-Continental Convergence.
Oceanic-Continental convergent boundaries:
It is a type of a Convergent Boundary which takes place when plates move toward each other. At Oceanic-Continental convergent boundaries, the plate moves under the continental plate thereby creating mountain ranges. The oceanic plate sinks into the subduction trench. Consequently, the subducting plate further shatters into smaller pieces which accumulate over the period of time and finally results in earthquakes and volcanoes.
When these plates meet, one of them subducts beneath the other and forms a deep trench. The subducted plate goes deep down towards the mantle and begins to melt. Hence, molten rock from these melting plates rises on to the surface of the Earth and results in volcanic eruptions. Thenceforward, Sea floor spreading occurs and the oceans become wide. In recent times, Europe and North America is moving apart by an average of 7.6 cm since the Atlantic Ocean is widening.
This phenomenon occurs when two continents meet straight on and neither among them is subducted since the continental rocks are relatively less in weight and resist a descending motion. As an alternative, the crust tends to collapse and is pushed upwards or at times sideways.
Transform Plate Boundaries are regions where plates slither one another. The rupture area that forms a transform plate boundary is known as a transform fault found in the ocean basin. A transform fault is formed between two different plates which are usually moving away from divergent plate boundary. However, transform faults are those regions where occasional earthquakes have occurs. While, on the other hand, Volcanoes rarely occur since magma or a melting subducting plate is absent.
Earthquake in India:
The 7.6Mw earthquake shook the region of Gujarat situated in India, took place on 26th January, 2001. t is regarded to be one of the most deadliest earthquake to strike India. The death toll was estimated to be 19,727 with around 166,000 lives being injured, 600,000 left homeless, 348,000 damaged houses, approximately the death of 20,000 cattle with an economic loss of $1.3 billion.
The cause of earthquake in India:
Studies show that around 60 percent of Indias land is under moderate seismic threat. The cause of this earthquake has been debatable since a long period of time. Generally, the Earthquakes occur due to the movement of plates. On analysis of certain studies, one and evaluate that the reason behind the Earthquakes in India is due to the change of plate boundary which resulted in stress accumulation in the zone near the junction of Arabian, Indian and Eurasian Plates. Hence Earthquakes in India are because of the interactions and connections between plate boundary and intraplate processes. However, Factors which contribute towards the occurrence of Earthquake of 2001 include Crustal weakening and strength, the Kachchh rift zone and the thinning of the lithosphere.
Plates and processes involved in earthquakes and volcanoes in India:
There are convective currents being induced at the centre of the Earth, which breaks the Earths crust. As a result these broken ridges and plate collide or move apart to cause earthquakes and volcanoes.
The earthquakes occur on huge scales. In India these earthquakes occur when the India Plate slides under the Burma Plate. This process takes several minutes. The India meets the Burma Plate, a part of the Eurasian Plate at the Sunda Trench. It is at that particular moment that the India Plate subducts beneath the Burma Plate and slides further and more deeper beneath the Burma Plate. This process continues until the temperature and pressure is raised to such an extent that it drives volatiles out of the plates thereby initiating the melt which occurs in the form of a volcano.
On the other hand, the sideways movement of the plates results in the inceased water levels of the sea bed thereby triggering the tsunami waves. This reduces the capacity of the Indian Ocean, finally contributing to a rise in the sea level. The Geological feature that forms at these types of boundaries would be volcanic mountain arcs. They rise up out of the continent as mountain ranges, but actually are volcanic and are known to spew out lava Oceanic-Continental convergent boundaries
Thus, the movement of Tectonic Plates cause harmful, devastating hazards such as earthquakes and volcanoes which can never be prevented but still, precautionary measures would save hundreds of lives and in short, out mother Earth.