Earthquakes are destructive natural phenomenon caused by tectonic activity occurring along plate edges and faults. They generally have a trail of destruction owning to the large areas affected, as well as the suddenness and unpredictability. The higher the magnitude of the earthquake on the Richter Scale, the greater the destruction it is likely to cause. Damages include the destruction of property, loss of life, disruptions in vital infrastructural services such as power and water supply, transportation and communications. Earthquakes can also have a major economic impact.
What is an Earthquake?
In simple terms, vibrations moving across the Earth’s crust, felt in the form of shaking and shifting of the ground is known as an earthquake. When stress builds up near the fault lines, or the boundaries where two tectonic plates meet, the lithosphere cracks or moves in order to accommodate the movement of the plates, thereby releasing the stress. This occurs in the form of released energy, that courses through the Earth’s crust in the form of waves, known as seismic waves. The tremors or ground shaking that people feel due to these waves is the most common form of an earthquake. Generally, people believe that earthquakes are cause only due to the collision and the vertical or horizontal shifting of the Earth’s tectonic plates. While this is, in fact, a major cause of earthquakes, they can also occur as a result of massive volcano eruptions, the crashing of meteors onto the Earth’s surface and nearly any natural occurrence that causes the ground beneath our feet to quake. Earthquakes can also be caused by human interference. For example, tremors felt after a nuclear blast, large explosions or the cave in of mines .
Earthquakes Hazard and Destructiveness
Earthquakes, even the natural ones, occur more often than most people realize. However, they commonly go unnoticed due to the low intensity of tremors. For example, as tectonic plates are constantly in a state of movement and slowly grind against each other, a series of ‘slow earthquakes’ are caused. While these do not generate significant seismic activity to cause tangible tremors, they do play a major role in the distribution of stress building up near fault lines. There are also those earthquakes that have the destructive power to raze entire cities. Possibly, the most destructive earthquake recorded was the one that triggered a massive tsunami in the Indian Ocean near Indonesia on 26th December, 2004. It is believed that this 9.0 magnitude earthquake was the equivalent of 23,000 of the atomic bombs used in Hiroshima in terms of energy released. It impacted 11 countries and led to over 150,000 people being declared dead or missing .
Earthquake’s do not directly kill people, it is the hazards that arise from the force of an earthquake that holds power to cause great destruction and loss. The most important hazard of an earthquake arises from the quaking ground itself. As the Earth’s crust shifts, and the seismic waves hit areas, the shaking ground can lead to buildings being damaged or even collapsing altogether. Other structures such as bridges, roads, underpasses, subways and so on are also badly affected by the tremors. Ground displacement can also have the same impact of structures and hence is also a major hazard. These falling and breaking structures tend to have a ‘domino’ effect in cities, where one poorly constructed structure can damage other buildings in the immediate vicinity. A majority of the loss of life and injuries are also caused as a result of damaged to structures. There have been several instances where inhabitants of a building have been buried under the debris of the collapsed structure for days .
Another hazard of Earthquakes arises in the form of floods caused by damage to levees and river dams, which eventually break altogether, thereby releasing massive amounts of water which may damage buildings or simply sweep them away in addition to drowning people. Fire is yet another major earthquake hazard as it causes much destruction even when the earthquake itself is over. Broken power and gas lines can trigger a fire or something as simple as a coal stove. As the water lines in these areas are usually disrupted as is transportation, emergency rescue teams find it difficult to reach the location in time and the fire can quickly spread and grow. The final hazard is that of a tsunami. As discussed earlier, while tsunamis are extremely rare, they cause damage in gargantuan proportions.
Can EQ be predicted?
Technological advances in the field of seismic sciences had made the prediction of earthquakes much more accurate than ever before. Yet, there is no certain way to predict the exact time, location and magnitude of an earthquake. However, areas that highly prone to tectonic shifts or volcanic activity can be identified and monitored to demark zones that can expect to experience an earthquake at anytime. First, there are areas that lie directly above known fault lines and seismic zones and these are monitored regularly to measure the buildup of tectonic stress. Modern seismology relies on Global Positioning Systems or GPs to accurately monitor tectonic shifts, magma movement and minor changes in the Earth’s crust across the world. This data is then used to draw maps, measurements and models that note the pace and direction in which plates are moving, thereby being able to predict when and where tectonic plates may be expected to interlock, leading to the formation of new fault lines. The stress levels on existing fault lines are also constantly monitored. Further, especially after the 2004 tsunami, oceanic earthquakes and volcano eruptions are also followed closely. Although these prediction systems do provide a degree of awareness, they can he harnessed to provide only a few minutes to a few hours worth of warning before an earthquake actually takes place. Yet, this time is enough for people living in high vulnerability areas to reach safe houses, which can at least reduce the loss in terms of human life.Locating Earthquakes
As discussed earlier, earthquakes vary greatly in their magnitude. Hence, while some are felt across a large areas, other may go undetected altogether. However, in order to better plan construction and hazards management in earthquake prone areas, it is crucial to identify such area and the likelihood of an earthquake taking place there. Seismographs have been used by geologists to record and measure the intensity and duration of seismic waves, which they can then analyze over a period of time to decipher whether earthquakes in a given areas are growing stronger. This information is then used to make a basic forecast of the vulnerability of an area or the likelihood of a high magnitude earthquake taking place. The earthquakes are measured through two methods, namely: a) intensity – the degree of damage that an earthquake inflicts, and b) magnitude – marked on the Richter scale, it is the measurement of the amplitude of waves and distance.
Works Cited
Curiosity. "What causes an earthquake?" 2011. Curiosity. 13 March 2013
MichiganTech. "What are Earthquake Hazards?" 2007. UPSeis - Michigan Technological University. 13 March 2013
National Geographic. "The dealiest tsunami in history?" 5 January 2005. National Geographic. 13 March 2013
