Natural events such as Earthquakes and tsunami disasters can occur in a place near the location of the Earth’s plates. There is a possibility that these events can occur anywhere and anytime in all parts of the Earth. Before discussing tectonic plates that are the cause of Earthquakes, first, let us discuss planet Earth.
As previously known, the planet Earth that we inhabit has a form that is not perfectly round, is fast or flat in the poles. No wonder the fingers on the equator are longer (6,378 km) than the radius of the line leading to the pole (6,356 km). The nickname as a blue planet is true because about 70% of the planet Earth consists of water.
Planet Earth itself is not formed from a solid unit. The Earth is composed of several layers, starting from the uppermost layer of the Earth’s crust, which is the residence of all living things and various kinds of life, then the upper sheath, the lower sheath, the outer core, and the last inner core.
Each layer of the Earth has different thicknesses; the thinnest layer of the Earth is the Earth’s crust (30 km). So it is not surprising if the Earth’s crust will easily experience a shift by the activity of the Earth’s tectonic plates because other layers of the Earth such as the Earth’s core are liquid and very hot.
We also know that the effects of Earthquakes are the movement of tectonic plates. Then, if the question arises, what causes the shift in the Earth’s plate. The question is very closely related to the structure of the Earth’s layer that has been mentioned above whereas there is a special science that studies all kinds of things that occur in the Earth’s crust, namely tectonics.
In the theory of plate movement, there is an Earth crust that has a hard and rigid nature, the layer is above the Earth’s mantle layer which is fluid so that it can move in any direction. Therefore, the Earth’s crust which is above the softer and movable layer results in the Earth’s crust (in this case the continent) being able to move in the direction of the Earth’s mantle beneath it.
The energy that causes movement in it (endogenous power) is called convection current. Convection currents themselves originate from the heating of the Earth’s core and in certain places; these currents rise to the surface and then spread horizontally.
Tectonic Movement
To better understand the causes of tectonic plate shifts, it is good to know what tectonic movements are. The tectonic movement itself is a process of movement of the Earth’s crust resulting in a high and low surface of the Earth so that tectonic movements are very closely related to the shape of the Earth’s surface relief because the results of tectonic movements will cause folds, grooves, cracks and also faults. The tectonic movement is divided into 2 parts, namely:
- Epirogenetic Movement
It is the movement of up and down of the Earth’s skin using slow energy and in a fairly large area. The epirogenetic movement itself is divided into 2 namely positive epirogenetic movements (pointing down, as a result, the land becomes descending, and seawater as if rising) and negative epirogenetic movements (pointing up, consequently a mountain or hill appears and seawater as if falling).
- Orogenetic Movement
This movement is faster than epirogenetic movements and has in areas that have a narrow scope. The form of orogenetic movements in the form of folds, cracks, and fractures.
The resulting fracture is also divided into 2, namely: Graben, lower fault, and higher fracture Horst. The two faults are a result of the stretching force on the plate.
In addition to fractures, the folds are also divided into 2 namely: Anticlinal, higher folds, and Synclinal, lower folds. Both folds are caused by plate compression.
The plate movement turns out to produce a part called plate boundary. The plate boundary is divided into 3 parts, namely, divergent plate boundaries, convergent plate boundaries, and fault plate boundaries.
Factors Causing Tectonic Plate Movements
The movement of this plate requires energy. This energy comes from the membrane of the Earth which is a large tangible clump that lies beneath the tectonic plate. The thickness of this Earth membrane reaches 2,800 km, consisting of rock material in the form of silicate compounds, arranged very intricately and some parts even merge. Not that this membrane is liquid, but rather soft and very sticky and has a very high temperature and pressure.
The deeper the temperature of the Earth’s membrane will get hotter. Because of the temperature difference between the upper part of the Earth’s membrane and the lower part of the Earth’s membrane, it makes the Earth’s membrane keep moving. This process of temperature difference produces a very large charged current that continues to move from the bottom up in a rotating manner. This current causes tectonic plates to move.
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Then, why does this current occur?
This happens because the lower part of the Earth’s membrane tries to move its very hot material to the top because there is a thickness difference between the lower layer and the upper layer of the Earth’s membrane. The top layer of the Earth membrane is quite thick and the rice so that some parts will drop down to a warmer temperature. This process takes place continuously without stopping.
Experts argue, around 300 million years ago on Earth, there was only one very large continent called Pangea. Over time, this continent slowly separated so as to produce Gondwana and Laurasia. 65 million years ago, Laurasia split into North America and Eurasia, and at that time also South America moved away from South Africa. 10 million to 20 million years ago, North America joined South America and the Continent of India united with Eurasia, while Australia was separated from Antarctica. Until now, the Australian continent has moved northward every year around 7 cm, plus Australia is on a tectonic plate which has the fastest movement between other tectonic plates. As a result of the movement of the plates that caused the Earthquake.
That was the explanation for the causes of tectonic plates shifting. Hopefully, the information above can be useful for you.