An earthquake is an intense thrilling vibration through the earth’s surface. An earthquake may range from a minor vibration (difficult to feel) to a devastating earth movement. An earthquake is a catastrophic shake of the surface of the earth, which can cause tremendous changes over and under the surface of the earth. In the historic review, earthquakes had remained a cause for the destruction of cities, and villages. Many many human habitats had been ruined due to the earthquakes. An earthquake may be caused due to a couple of reasons, which are being discussed below.
01. Earthquake due to Seismic Energy:
This is one of the basic and foremost reasons for an earthquake. There are several kinds of earthquake waves including primary waves (P-waves), secondary waves (S-waves), and Love waves (L-waves/ Q-waves). However, Surface waves consist of several major types and are known as long waves. When these waves travel through earth mass causes severe disturbance and shake and thrill in the hard crust of the earth. This type of disturbance is actually the earthquake. Most of the earthquakes in the world’s history are the result of Seismic Waves. These waves are created by the sudden release of a stressed mass. Clarifying this phenomenon through an experiment is: Take two puffs of foam. Put these two puff along with each other in a way that their walls are touching each other. Then move the two puffs in opposite directions. For a few seconds, the walls of the puff will keep sticky with each other with a strain. But when the strain reaches its ultimate end, the foams will suddenly move in a transform position. This movement will cause severe vibration in both the puffs of foam. The same principle is with the landmasses and tectonic plates. The sudden release of the strained bodies creates intense vibration. This vibration results in earthquakes. If this earth’s movement is under the seawater, it causes Tsunami.
02. Compression in the earth’s crust:
The rupture in the million tons of water would have hastened the earth’s shaking. No geological process can actually come up with such a huge concentration of mass in such a small area except for a volcano. It is history, which has proved how large reservoirs of water created by dams have caused earthquakes. Examples include from Zambia to Greece and Canada to China. The 2008 Sichuan, China earthquake, which killed nearly 70,000 people. It is believed that it was triggered by the construction of the Zipping Dam nearby.
There have been many more examples of Earthquakes in Australia which are believed to be caused by the movements along faults. This could be a result of the compression in the Earth’s crust. You can determine the size or magnitude of earthquakes by measuring the actual amplitude of the seismic waves which gets recorded on a seismograph.
03. Groundwater extraction:
When the groundwater is extracted from the Earth it causes the water table to drop thus destabilizing an existing fault. This can a valid reason for an Earthquake. For example, the 2011 Lorca earthquake. This 2011 earthquake in Lorca, Spain caused a huge amount of destruction for its 5.1 magnitudes as was recorded in the Richter scale. The destruction may be much more severe as the epicenter of the Earthquake is neither so deeper nor away from the population.
04. Geothermal drilling causes earthquakes:
Salton Sea Geothermal Field and The Geysers Geothermal Field are examples of earthquakes caused by geothermal power plants. Seismic activity had increased around the Salton Sea as geothermal field operations around the area had ramped up. While these earthquakes in themselves may not be the main cause of damage but the other interaction with bigger faults like San Andreas could be one. Earthquake swarms include bursts of dozens of small quakes prevailing below magnitude 6 or so-happen regularly along the Salton Sea. Examples of such an earthquake include: – Salton Sea Geothermal Field and The Geysers Geothermal Field.
05. Tracking and injection wells:
The process of hydraulic fracturing or cracking is the only way to extract oil fluid from the earth. The fluid caused due to the extraction of liquids can seep out and also lubricate faults. This can cause them to slip more easily. For example- 2011 Oklahoma earthquake- A study had pointed out that Seismic activity in Oklahoma has shot up along with the rise of fracking. Earthquake swarms have become a regular occurrence in the region. The number of earthquakes had shot up from a dozen in 2008 to over 1,000 in 2010.
06. Weight of Big and massive buildings:
Big skyscrapers and buildings can put immense pressure on the earth’s surface. It can cause the rudimentary rocks to even crack. As a study points out, that Taipei 101’s especially huge mass of 770,000 tons is presently putting too much pressure on the soft sedimentary rock below. The pressure is further is increased when massive steel and stone are used in the construction of buildings. These massive buildings create an imbalance in the isostatic equilibrium among different parts of the earth’s surface. Moreover, these buildings cause cracks and breaks in the rocks. The breaking of these rocks causes earthquakes. But generally, this type of Earthquake is very rare and of low magnitude.
07. Tectonic movements of the earth:
The crust or the outermost shell of the Earth is cracked. The main cause for this crack is the movement of molten mantel which is just beneath the hard crustal shell. Each consolidated part of the cracked crust is called a Tectonic plate. There are many Tectonic plates namely, Indian Plate, Eurasian Plate, African plate, Antarctic plate, Eurasian plate, Indo-Australian plate, North American plate, Pacific plate, and South American plate. Tectonic Earthquakes are caused when the crust becomes subjected to strain and eventually starts moving. This movement causes Earthquakes. These plates are either moving apart from one another or moving toward one another, or this movement may be transformed. In each case the boundaries possess stress. After severe stress, these plates break the stress and start moving. Thus causing an effect of vibration and thrilling resulting earthquakes.
Example: – Due to tectonic movements, San Francisco has noticed many small shakes.
Earth’s crust is divided into large segments ( fragments) separated along ridges. These segments are called plates (Lithospheric Plates). The term tectonic plates are used to describe the active mobile nature of these plates. These plates explain the drifting movement of the continents. They can collide and cause great destruction. The collision can result in volcanic activity, earthquake,s and mountain building. According to geologists, these are about twenty major plates out of which the following are the prominent: The pacific plate (It covers most of the Pacific Ocean floor from South Alaska to Antarctic Plates). The North American plate ( Covers North America) The Eurasian Plate (It carrier all Eurasian Landmass North of Himalayas) The African Plate (Africa and Madagascar) The South American plate (Carries South American) The Australian- India Plate ( Carries Australian and India). The Antarctic Plate (Carries Antarctic Landmass) The Nazca Plates ( Between South America and Pacific pacific Plate) The Caribbean Plate ( Central America & Caribbean region) The Cocos Plate ( Lies north of Nazca Plate). The Rivera Plate ( Oceanic crust) The Arabian Plate ( Arabian region) The Philippine Plates ( Between Pacific & Eurasian Plate) The Scotia Plates ( South of the Latin America) The Juan de Fuca Plate ( Support Western Coast of North America near US-Canada border). The Gorda Plates (South of Juan de Fuca Plates).
08. Volcanic eruptions:
A volcanic eruption is also a major cause of Earthquakes. Volcanic earthquakes are very less likely than Tectonic ones. Earthquake is triggered whenever there is an explosion of a volcanic eruption. The volcanic eruption is quite similar to a powerful bomb blast. This explosion cause vibration on the surface of Earth. The vibration travels all through the Earth depending on its intensity, causing an earthquake.
09. Disturbance on the surface of Earth:
Basically, all earthquakes are majorly are the result of a disturbance in the outer crust on the ephemeral surface of the earth. Anything which will tend to destroy the perfect equilibrium or the balance of the globe will likely cause an earthquake. Each side and every part must necessarily carry the same weight and the state of isostasy must be maintained. Whenever there is an imbalance between two interconnected masses, a movement in the masses may occur. This movement will create a disturbance within the surface of Earth, which creates vibration and thrilling in the crust, which is known as an earthquake.
10. Havoc of a Powerful Bomb Blast:
Whenever there is a powerful bomb like a thermonuclear bomb detonated, waves of high magnitude are released through the Earth’s mass. These waves are composed of P-waves, S-wave, and L-waves. Although such types of earthquakes are not much destructive, however, it can harm weak buildings.