Causes and Effects of Earthquakes
An earthquake also referred to as tremor or quake is the trembling that happens on the Earth’s surface as a result of sudden energy release to the Earth lithosphere, therefore, developing seismic waves. Earthquakes vary in sizes, for instance, there are quakes that are weak and are not enough to be felt by people or even destroy cities. However, there are large earthquakes that shake and cause ground displacement. Earthquakes can also result in landslides, property destruction as well as ground rapture. The largest earthquake is referred to as main-shock and is always followed by aftershocks that are experienced after the main shock. However, the world’s largest earthquake was experienced in the 1960 near Valdivia, South Chile and had around 9.5 magnitudes (Braitenberg and Rabinovich, 2017). This quake is also known as the ‘Great Chilean Earthquake’ that left nearly 2 million people homeless and thousands of buildings destroyed (Braitenberg and Rabinovich, 2017). Accordingly, it is imperative to understand both causes as well as impacts of earthquakes.
Causes of Earthquakes
Earthquakes happen as a result of various factors such as natural calamities and human activities. One of the natural causes of earthquakes is tectonic movements.
The Tectonic Movements
Tectonic movements are the disturbance that happens inside the earth. However, this movement creates forces that develop changes on the surface of the earth and therefore physical features like rift valleys, plateaus and mountains are created (Betbeder‐Matibet, 2008). Many of the disastrous earthquakes happen because of the tectonic forces that create pressure and tension where stress begins to accumulate inside the earth. To explain this, the Earth contains four main layers that comprise; the inner core, outer core, crest, as well as the mantle. The crust as well as the upper layer of mantle creates the thin skin of the planet. Furthermore, these layers of the Earth’s surface are made up of many puzzle-like pieces that are always in a constant slow motion and these puzzle pieces are referred to tectonics plates (Betbeder‐Matibet, 2008). The ends of these tectonic plates also referred as plate boundaries comprises numerous faults and many of the earthquakes happen on these faults because the plate boundaries are rough and get trapped while the tectonic plates keep moving. Moreover, when these edges unstuck from the faults they create an earthquake.
Earthquakes are also caused by volcanic eruptions. Volcanoes happen as a result of the magma movement. The magma produces forces on the rocks that crack the rock. Therefore, the magma streams in the cracks and builds up more pressure leading to more cracks resulting in small earthquakes. In addition, when the volcano plumbing system opens up and magma starts flowing out, continuous earthquake waves referred to as harmonic tremor are created (Betbeder‐Matibet, 2008). The volcanic tremor has been used as a signal to predict eruptions, for instance, the eruptions that happened in Mount St. Helens in 1980 (Betbeder‐Matibet, 2008).
Earthquakes are also caused by human activities particularly by the wastewater produced by the gas and oil drilling operations injected into the ground (Griggs, 2017). However, this activity does not result in huge quakes although they can cause big impacts. Research by the United States Geological Survey (USGS) about the induced earthquakes suggests that many of the earthquakes that happened in Oklahoma might have been as a result of wastewater from the oil industry (Griggs, 2017). Also, induced seismicity can happen through induction of carbon dioxide produced by the fossil fuel and other sources in the Earth’s crust. In addition, man-made earthquakes decrease and increase following the industrial activities which are hard to anticipate.
Effects of the Earthquakes
Ground Rapture and Landslides
Earthquakes bring about massive destruction such as ground rapture as well as landslides. However, the ground rapture is the primary impact caused by the large earthquakes. The severity of these effects relies on the complex combination of the quake magnitude, geomorphological conditions as well as the distance from epicenter which can reduce or maximize the wave propagation. Moreover, ground rupture and landslides are major risks to the engineering structures like nuclear power stations and dams. For example, in 1970, in the Coast of Peru, an earthquake caused a landslide that started 80 miles far from the quake (Zeilinga et al., 2011). This slide was estimated to be nearly 30 meters and killed more than 18,000 individuals (Zeilinga et al., 2011).
Death and Injuries
Moreover, many of the earthquakes are death related since they result in construction collapse which leads to deaths of many people. For instance, in southern Italy, around 100,000 individuals died in 1909 due to earthquake which happened in this area (Zeilinga et al., 2011). Many of this people die because of the collapsible structures and others escape this event in severe injuries. Yet, even a minor shaking can result in thousands of casualties whenever a building collapses and also lead to depression and mental consequences to survivors (Zeilinga et al., 2011). The level of an earthquake damage relies on the duration and amplitude of the shaking. Therefore, when the amplitude is large, it results in large earthquakes.
Tsunami is another effect brought by the earthquakes. Tsunamis are harbor waves that happen as a result of the vertical offset of the ocean floor caused by volcanic deformation and earthquakes. Sometimes tsunamis rise to nearly 20-25 meters and cause massive damages to people and properties especially in coastal regions (Zeilinga et al., 2011). In 1896 in Japanese, an earthquake generated a tsunami which destroyed the shore with waves rising up to 100 feet and 22,000 people died (Zeilinga et al., 2011). When an earthquake occurs, the sudden shaking changes the ocean’s elevation then initiating the water waves to travel outside the seafloor region. Large waves caused by earthquakes can overrun a coastal region within minutes and also flow in thousands of kilometers in an open ocean causing massive destructions.
Earthquakes are suggested to result in soil liquefaction (Zeilinga et al., 2011). This means that, when ground shaking happens, water-saturated materials, for example, the sand loses their strength and turns from solid to liquid. Soil liquefaction results in rigid structures sinking or tilting. For instance, in 1964, soil liquefaction made many buildings to sink and collapse in Alaska earthquake (Zeilinga et al., 2011).Also; other things relying on this soil for support can tilt and collapse.
Earthquake is a sudden vibration and shaking of the surface of the earth which is caused by the underground movement by volcanic activity or movement of tectonic plates. Scientists use seismographs to record earthquakes. However, earthquakes cannot be detected and whenever they occur, they can cause massive damages to property and even kill people. Moreover, earthquakes can be caused by human activities particularly the wastewater produced by the gas and oil drilling operations injected into the ground. Earthquakes lead to massive destruction such as ground rapture as well as landslides. It is suggested that there are many deaths as well as severe injuries that happen as a result of earthquakes in many countries.
- Betbeder‐Matibet, J. (2008). Causes of Earthquakes. Seismic Engineering, 5-53.
- Braitenberg, C., & Rabinovich, A. B. (2017). The Chile-2015 (Illapel) Earthquake and Tsunami.
- Griggs M. B, 2017. Man-made earthquakes will continue to shake the country. Retrieved from: https://www.popsci.com/2017-earthquake-damage-forecast
- Zeilinga, B. J., Sanders, D. T., & Ballard, R. D. (2011). Volcanoes in Human History: The Far-Reaching Effects of Major Eruptions. Princeton: Princeton University Press.