The Causes of Earthquakes - Research Paper Example

Earthquakes Introduction Geological hazard refer to phenomenal geologic occurrences that upset the geological make up of the earth in turn causing adverse effects detrimental to lives of organisms and property. Arguably earthquakes are the most dangerous of the geological hazards, and the adverse effects on earth second to no other hazard humanity has had to face. It is on this premise that I researched on earthquakes as a geologic hazard (Fradin & Fradin, 2008). Scientists have researched a lot about earthquakes going further to identify areas with high exposure to earthquake. The world at large has appreciated the enormous damages that earthquakes cause and responded positively by setting up disaster management teams which aid in an earthquake. Although the risk to earthquakes is higher in certain geographical regions than others, the fact that an earthquake has never occurred in a particular place is no guarantee that it would never occur. It is based on that premise that I opted to research on earthquakes with an aim of examining the causes, the effects, possible preventions and the responsibility of governments and the people at large (Fountain, 2012). Causes of Earthquakes At or below the surface of the earth within the crust which is the third layer of the earth, a sudden energy release occasions seismic waves which trigger the movement or tremor of the crust. It is this phenomenal activity that constitutes an earthquake. Two foremost origins are linked to earthquakes; tectonic forces associated with plate margins and faults and explosive volcanic activity. Tectonic Earthquakes The theory of tectonic plates posits that the crust of the earth is composed of numerous plates which are large and float freely on the mantle. The free flow of the plates enables their movement drifting as independent layers towards, away and against each other. The drifting though gradual in nature triggers the earthquakes when the layers collide or slide against each other. This process can be explained by the Elastic rebound theory. Essentially, if one holds both sides of a twig and applies pressure on both ends, the pressure piles in the middle until when the elastic limit of the twig is exceeded then it snaps suddenly with a consequent release of energy. The energy traditionally causes the twig to vibrate (Simon, 2006). Retrieved from Similarly when the layers of the crust collide with each other, the pressure applied on the end of a particular layer forces is spread all over the plate(layer) and it succumbs by snapping at a particular point just like the twig snaps in the middle. The snapping is what occasions the earthquake. A perfect example of this kind of earthquake was the San Andreas Fault of California. The plates that snapped were the Pacific Plate and the North American Plate. It is reported that both plates were moving in a similar course but at dissimilar speeds so that one was faster than the other. This brought about the collision due to friction as one plate passes over another. Eventually the grinding was big enough to cause an earthquake. Scientists have observed that the two plates continue to grind against each other occasioning small earthquakes annually. However, grinding in large amounts would cause bigger earthquakes whose effects would be detrimental just as was the 1989 earthquake (Fradin & Fradin, 2008). Image - The San Andreas Fault. Retrieved from: Further classification of tectonic earthquakes considers the type of fault. Ideally, there are three major types of faults that would lead to earthquakes. These are normal, strike-slip and the reverse faults. Normal faults occur when the displacement along the fault is in the bearing of the dip. This causes a vertical component movement during the displacement. The normal fault is associated with the crust layers being extended during the drifting. Reverse faults on the other hand are associated with the crust layer attempting to shorten especially at the convergent boundaries. When two sides of the fault slip past each other in a horizontal position the strike-slip faulting occurs. The strike-slip faults are the most dangerous being of the highest magnitude of up to about magnitude eight (Walker, 2007). Interestingly the determinant of the effects of the earthquake in terms of magnitude is not the length of the fault but rather the width of the fault. The relationship is directly proportional between the width of the fault and the magnitude of the earthquake. It is observed by scientists that along the converging plate margins the dip angle is very shallow while the width of the plane is large. Very strong earthquakes such as the Tohoku earthquake of 2011 and the Alaska earthquake in 1964 were fault earthquakes with the width of the plane between fifty to hundred kilometers. In addition the stress levels experienced varies according to the type of fault. Reverse faults experience the highest stress levels with the strike-slip being intermediate and the normal faults experiences the least level of stress. The stress levels eventually determine the amount of energy released that causes the seismic waves. This would in turn determine the strength of the earthquake and its effects on the earth’s surface. Consequently, the reverse fault definitely leads to the most enormous earthquake in terms of magnitude (Walker, 2007). Volcanic Earthquakes These earthquakes are triggered by explosive volcanic eruptions. Volcanic eruptions refer to the release of hot magma, volcanic ash and gases into the surface of the earth through what are called volcanoes. Ordinarily not all volcanoes lead to volcanic eruptions. When volcanic eruptions occur, they can cause earthquakes. It is important to note that these types of earthquakes are rare. The explosion of a volcano is what causes the earthquake. The lava produced by volcanoes vary, incidentally the acidic lava producing volcanoes lead to earthquakes (Fountain, 2012). Retrieved from: The science behind this occurrence is that acidic lava cools and settles very quickly upon being released into the earth’s surface. This is because of the contact it makes with the air on the earth which cools it down. The lava then settles on the volcano blocking the volcanic vent. The blockage of the vent can only be undone by a build-up of pressure which would effectively explode the blockage away. Ordinarily, such an explosion would occasion the formation of mountains. A typical example is the formation of Mt. St Helens which was a fairly small volcanic eruption. However when the pressure is extra ordinary, the resultant explosion leads to an earthquake of considerable magnitude. Case in point is the Krakatoa earthquake in Indonesia which was audible in Australia, which is over five thousand kilometers. Of course the shockwaves resulted into a series of tsunami (Fradin & Fradin, 2008). Retrieved from: Effects of Earthquakes The effects of earthquakes are categorized into two; primary effects and secondary effects. Primary effects accompany the earthquake itself and could be effects such as collapsing buildings and tsunamis. Secondary effects are effects experienced after the earthquake such as interruption of electricity and fires. The above effects of earthquakes can be examined from the perspective of effects which affect humans directly and effects which affect the environment (Fradin & Fradin, 2008). Earthquakes displace people from their homes. This is a consequence of buildings collapsing when the earthquake takes place. The Haiti Earthquake displaced about one and a half million people into more than one thousand settlement (Fountain, 2012). Humanitarian crises accompany displacement of people from their homes. Displaced people are forced to suffer from hunger dehydration and bear with unsanitary conditions after earthquakes. Diseases are a threat to settlements that aggrieved inhabitants seek refuge especially in earthquakes which are accompanied by tsunamis. Children are an easy target for respiratory complications because most of them flee their homes without adequate clothing. Earthquakes are very hazardous to the health of their victims. It is common to see individuals who suffer from broken bones or body injuries afar earthquakes. Most of these injuries are a result of buildings collapsing on people. In some cases, individuals get trapped in debris and are rescued successfully. A number of these lucky survivors may end up losing a part of their body through amputation depending on how they got trapped under the rubble. A study by Olivet Heart Naples among people living in Naples, Italy revealed that earthquakes have certain psychological effects among people who have experienced it. The psychosomatic conditions which the study identified were such as depression, anxiety, obsessive compulsivity, interpersonal sensitivity, hostility, paranoia and psychotics. Death is a common feature in earthquake. The death toll of the Japan earthquake in 2011 was beyond fifteen thousand people (Fradin & Fradin, 2008). Governments suffer economic losses as a result of earthquakes. The first loss being that the earthquake is an unplanned event and recovery from it may require governments to chip in funds that would have been directed to other profitable pursuits. To exemplify this, after the Christchurch earthquake in New Zealand, its government was forced to initiate a salary cut among high income earners in order to raise two hundred and fifty million dollars to stimulate recovery from the earthquakes. Other losses arise from earthquakes affecting industries which governments depend on. After the Japan earthquake and tsunami, Japan operated on a shortfall of about three billion dollars in its budget. This is because the earthquake shut down most of Japan’s nuclear industry. Japan relies heavily on nuclear power to run its industries and generate electricity for its residents. Since, the nuclear power was no longer accessible; Japan had to import natural gas and other fossil fuels – which were unplanned spending. The negative economic effects also extend to private individuals who own companies and small businesses in regions that have been torn apart by earthquakes. Many find themselves unable to operate as usual because either their premises has been affected or because their customers are not interested in business at that time due to pressing matters such as rebuilding their homes (Simon, 2006). Earthquakes affect communication from one point to another. This is due to breakdown in infrastructure. For example, Electrical lines are often felled in earthquakes. Most communication tools today use electricity hence in the absence of electricity; the possibility of communication elsewhere in the country is hard. In addition, roads and bridges also succumb to earthquakes and break off or collapse. This makes access to areas which have been hit by earthquakes hard. The first effect of earthquakes on the environment is its effect on the manmade environment. Earthquakes cause the collapse of buildings and shatter many structures such as playgrounds and radio communication towers. Earthquakes cause extensive damage of property in this process. For example, auto mobiles may be crushed as a result of buildings falling on them or their being thrown against other property by the tremors. Earthquakes also pollute the man made environment by littering affected cities and exposing sewage to the inhabitants. Dust caused by debris in earthquakes also contributes to environmental pollution after an earthquake (Walker, 2007). Earthquakes lead to other catastrophes such as earthquakes and mudslides. Earthquakes cause tsunamis when they occur in oceans and mud slides when they occur in regions that are characterized by loose mud. These events are known as mass wasting. The process by which some of these events may occur is through liquefaction. This is whereby, sediment with high water content moves down a slope. Tsunamis are a result of disarticulation in the ocean floor caused by a tremor. This displacement is big enough to create a rise or a fall in the water levels of the water body. Buildings often sink in this process. Earthquakes also cause fires. These occur when they expose electrical lines and oil pipelines to conditions which trigger their flammability (Walker, 2007). Earthquakes also initiate the fatality and displacement of animals. For example, animals which make homes in trees are disadvantages when the tree is felled by an earth tremor. The 2011 earthquake of Japan caused the death of numerous sea animals and birds which lived close by the sea. Animals which make their homes in the ground also have to find new habitats incase the place they have made homes in have been hit by earthquakes. Earthquakes gave some positive effects too. Earthquakes expose minerals and rock to the surface because they cause breakage on the earth’s crust. Water tables also shift as a result of earthquakes more so to the advantage of communities living in the affected areas. However, not all shifts in the water table turn out to be beneficial because in some cases, the water finds a fault line within the earth’s crust that it seeps into. Water, in such cases, goes moves further away from the earth surface (Walker, 2007). Earthquakes have an interesting effect on the length of day of Earth. For example, the earthquake in Japan in 2011 reduced the length of day by about 1.8 microseconds. It is not a noticeable effect but is one of fact. The principle being this effect is that an earthquake redistributes the earth’s mass and hence causes the earth to rotate faster hence shortening the length of a day (Simon, 2006). Preparedness and Prevention of Earthquakes The occurrence of earthquakes being natural phenomena, it is only possible to prepare for the disaster rather to prevent it from occurring. The greatest achievement that scientists have made and continue to research on is on the prediction of an occurrence of earthquakes. Technology already exists that can tell places likely to suffer earthquakes giving a duration in terms of years. The American Seismological society has set high standards before accepting a prediction has true and factual. This is because of the tension that news that an earthquake could occur creates among the people (Simon, 2006). Generally, governments have put their scientists on the ground to observe the movements of the plates and report to the people any signs of an earthquake occurring. In California, Japan and New Zealand special equipment exist that give warnings on the movement of plates. This is possible as the instruments can detect the movement of land masses even if only very slight movements. The collection of gases in ground water is also a typical sign that heralds the coming of possible earthquakes. In the United States which is fully susceptible to earthquakes due to its geographic locations, it is a government responsibility to inform citizens of any signs of a possible earthquake (Fountain, 2012). The predictive models used by scientists are numerous. It is important to note that thus far, no specific model has one hundred percent surety. Most of the methods are complementary to each other. Seismic activity involves the analysis of past patterns to foretell the prospective patterns. Foreshocks which are smaller earthquakes have been used over time to predict the possibility of a bigger earthquake occurring. Further the release of emissions not common in areas around fault lines could be a precursor of eminent danger (Walker, 2007). Some scientists have attempted to lessen the strength of earthquakes. They have poured water along fault lines where two or more layers are grinding to reduce the friction. These scientists argue that this in turn reduces the magnitude of the earthquake when and if it finally occurs. While preventing earthquake has been a tall order to the world, scientists have come up with ways of surviving the earthquakes. These precautions mitigate the effects of earthquakes on the lives of organisms and preserve the property from destruction. Earthquake engineering for instance, deals with the science that considers the impact of earthquakes on buildings and structures with the aim of designing structures in readiness of earthquakes. To this end, architects are designing earthquake proof structures. In these structures the foundation is stronger and the building survives mere tremors of the earth’s surface. In addition, the scientists have advised for construction on rock rather than gravel. The buildings are built of steel frameworks or reinforced with concrete so as to stand even during earth tremors. Interestingly the Transamerica building in the heart of San Francisco is build on the model using steel framework (Simon, 2006). Academicians have also developed curricula to provide lessons on disaster management. Reynolds international offers lessons on earthquake preparedness strategies to individual citizens. The managing director, Professor Reynolds cites the United Nations Development Program report which attributes thirty percent of the casualties of earthquakes to lack of knowledge on disaster preparedness. It is crucial therefore for everyone to acquire lessons on preparedness against earthquakes (Walker, 2007). Conclusion Earthquakes indeed are hazards in the world. While the causes are not within man’s control, the effects are so adverse to the existence of man and the preservation of property that we must appreciate and learn on how to survive the earthquakes. Earthquakes can occur anywhere and it is not prudent to think of a place as safe ground (Fradin & Fradin, 2008). References Fountain, H. (2012, April 4). Earthquakes. The New York Times , 1. Fradin, J., & Fradin, D. (2008). Earthquakes. New York: National Geographic Society. Kusky, T. M. (2008). Earthquakes: Plate Tectonics and Earthquake Hazards (1 ed.). New York: Facts On File. Simon, S. (2006). Earthquakes. New York: HarperCollins Publishers. Walker, S. M. (2007). Earthquakes. Minneapolis: Lerner Publications. Read More