Environmental Risks, Probability, and the Logical Tree of a Tsunami - Assignment Example

Introduction Tsunamis are series of waves that occur in large masses of water like the ocean and are characterised by a displacement of a substantial amount of the water (J. Fradin and D. Fradin, 2008 p.1; Harvey 1971). This paper examines tsunamis as an environmental risk, and provides a logic tree of causes and effects of a tsunami. It also identifies the scientific approach for quantifying the pathways risks and weaknesses of these approaches, assesses the feasibility of controlling these risks, compares the likelihood and magnitude of these risks with that of other environment risks, and evaluates people’s perceptions on these risks. An environmental risk A tsunami is an environmental risk. This is because it can cause death to both human beings and other living things as well as destroy properties and infrastructure (Harvey 1971; Kajikawa 2009, p.5). This destruction can further result in release and exposure of toxic substances that are harmful to the environment. Tsunamis also cause disturbances and imbalance of ecosystems (Dudley & Lee 1998, p.11), and destroy landscapes. The effects of a tsunami are also experienced in terms of indirect loss caused by it (Kajikawa 2009, p.10). The structure of pathways between potential causes and consequences of a tsunami Figure 1. a logic tree diagram for a tsunami representing the structure of pathways between potential sources of harm and possible consequences Scientific approaches for quantifying a selected sample of pathways on the logic Figure 2. a selected sample of pathways ( links) on the tsunami logic tree The rectangles represents the nodes, while the arrows indicate the links. The following scientific approaches can be used to quantify the particular pathways: In A, geological seismography would be ideal in quantifying the seismic activities or earthquakes. This entaild the use of seismographic detection to identify the location and intensity of seismic waves, and using geological knowledge to interpret the significance of the waves. In B, geological subsurface mapping and geological survey methods would be useful in quantifying risks associated with large water bodies. This would include use of field-based geophysical methods such as seismic surveys, electrical-resistivity tomography, and ground-penetrating radar. In C, both laboratory and field experiments on geophysical fluid dynamics would be useful in quantification of the risks linked to water displacement of large water bodies. In D and E, marine physics or physical oceanography method would be ideal in quantification of risks associated with both negative and actual wave travel to the coastline. F could be assessed through marine engineering, while G could be quantified through damage assessment case studies. Damage assessment includes estimation of destroyed properties and infrastructure. In H, containment engineering methods could be applied in quantification of the spread toxic waste resulting from a tsunami. In I, toxicology would be useful in risks quantification of this pathway. In J and K, statistics of disaster-based accident would be useful in their quantification. Weaknesses in available scientific knowledge for quantifying the selected pathways The use of geology and seismography knowledge in quantification of earthquakes has some weaknesses. Even though it is possible to detect seismic waves of importance, it is not easy to accurately link these waves to imminence of a tsunami. This is because much of geological information such as structural composition of the earth is derived from samples (Reddi & Inyang 2000, p.68), and prediction using this method provides generalized information. Therefore, this knowledge is only able to provide estimates. Similarly, use of samples in geological subsurface mapping and geological survey methods provide estimated data. The weaknesses in marine physics or physical oceanography, marine engineering, and accident statistics, also, rely on sample data and estimation. More to the weaknesses of these knowledge is use of assumptions in some instances. The weaknesses in geophysical fluid dynamics are linked to the variations of various conditions. While lab analysis of the behaviour and nature of fluid or - in this case – of displaced water is important, it may not yield similar results to the actual occurrence of water displacement in an ocean. This is because there are certain underlying factors that may affect the actual outcome in a field setup (Pedlosky 1987, p.26), but not in laboratory set up. Furthermore, various water displacement in the ocean or other large water body varies (Reddi & Inyang 2000). Therefore, knowledge of geophysical fluid may not necessary predict the exact nature of occurrence of a tsunami. Similar to geophysical fluid dynamics, containment engineering involves lab experiments that are performed under distinct conditions to the prevailing conditions in a tsunami scenario. On that regard, therefore, this knowledge may be limited in providing all the factors present in a real situation to allow accurate quantification. For toxicology, the weakness lies in the means of establishing every possible toxic material that is present at a particular area. Assessment of the feasibility of controlling risk It is not ultimate that a tsunami is preventable, but there are measures that can mitigate its occurrence or its effects. Some tsunamis are caused by natural occurrences such as earthquakes, volcanic eruption, and mass movements. In such a scenario, it is not possible to prevent its occurrence (Dudley & Lee 1998, p.45; Harvey 1971). However, in some instances, these natural events are triggered by human activities such as use of explosives that are possible to control. These human activities are potential causes of a tsunami or other natural occurrences that cause a tsunami and these activities can be regulated. Escaping or avoiding contact with a tsunami is also a possible control measure. This involve clearing people from the coastline and areas close to it to avoid drowning or its direct impact. In addition, moving to a high elevation where a tsunami wave cannot reach is a practical measure that can prevent people from the consequences of a tsunami (Dudley & Lee 1998, p.68). Other measures such as minimizing toxic wastes within areas that are vulnerable to tsunamis are important. In case there are toxic wastes in such area, they could be stored in tight sealed containers that can withstand the impact of a tsunami. These measures are possible. However, spread of toxic materials may not be entirely prevented due to presence of toxic wastes that lie in the environment. Damage of properties and infrastructure can be minimized, although not prevented altogether. Mitigation could be achieved through enhanced structural integrity of buildings and other structures in tsunami prone areas. People can also avoid constructing residential buildings and hotels at very close proximity to the coastline. It is also possible to provide tsunami warning systems that provide accurate information. More to this, people – especially those visiting beaches - should be educated on the nature and dangers of tsunamis to allow them escape when they sense its imminence. This, together with provision of escape routes are practical control measures of tsunami risks. Comparison of the likelihood and magnitude of tsunami risk with that of other types of environment risk. The likelihood of a tsunami risk may be higher than that of other types of environmental risk depending on various factors. The likelihood of a tsunami occurrence varies with the geologic formation of a region. There are areas that are more prone to a tsunami due to their close proximity to a large water body, and activeness of natural activities such as plate tectonic movement, earthquake, mass movement, and volcanic activities. On the other hand, the likelihood of a tsunami risk is low in some areas because such natural activities are minimal. However, since earthquakes and other causes of tsunamis can be unpredictable, costal regions remain at a risk of a tsunami, while some are not at risk at all because they are not close to a large water body. Therefore, in comparison, the likelihood of a tsunami risk may be higher than that of other types of environmental risk in areas that are prone to tsunamis. However, some areas are more prone to other environmental risks such as forest fires, gas spill, and other natural disasters as opposed to a tsunami. The magnitude of a tsunami risk, on the other hand, may be higher or lower than that of other environmental risks depending on its intensity and the preparedness to mitigate its effects. When tsunamis occur, they often cause great damage and loss of life (Västfjäll, Peters & Slovic 2008), especially if there were no prior signs to its occurrence and/or if people lack knowledge about tsunamis (Harvey 1971; Kajikawa 2009). Nonetheless, the magnitude of some other environmental risks such as forest fires may be greater, especially if such fires are difficult to control and if large proportion of people and properties interact with fuels of such fires. Thus, an environmental risk is dependent on several factors that may make it more likely to occur or have greater impact than other environmental risks. Evaluation of people’s perceptions of a tsunami, and comparison to other risks There are various perceptions on the risk of tsunamis, and some are valid while other are incorrect (Kurita, Arakida & Colombage 2007). Some communities have linked the occurrences of tsunamis to punitive actions of a supernatural being (Kurita, Arakida & Colombage 2007). However, science indicates that such a believe is misplaced because geological knowledge provides evidence on the causes of tsunamis. It is also believed widely that tsunamis are caused by earthquakes (Kurita, Arakida & Colombage 2007). While this believe is true, there is omission of other causative factors such as human activities as well as natural occurrences such as volcanic eruptions, mass movement, and bolides impacts. It is also perceived in some sector that people can protect themselves by getting in mosques and temples. The validity of this perception depends on the other factors such as structural integrity and elevation of the building as opposed to just the basic fact of a building being a religious outfit. Some people also believe that education about tsunamis is important in mitigating their risks, while other believe it is not important. Research indicate that knowledge of tsunamis may reduce its effects, but this depends on other factors (Kurita, Arakida & Colombage 2007). Thus, even if people understood the nature of tsunamis, it may not be possible to save lives or properties in some situations (Kurita, Arakida & Colombage 2007) such as when a tsunami approaches without warning signs or penetrates inland more than expected, and people are not able to escape from it. The perceptions of tsunamis are comparable to those of other natural risks. Some people, especially those of religious orientation or those without formal education, attach dogma to occurrences of environmantal risk. Moreover, the perception on the importance of education on various environmental risk depends more on individuals, communities and other factors other than on the type of a risk (Västfjäll, Peters & Slovic 2008) Conclusion This paper has justified tsunamis as environmental risks, presented a logic tree of the structural pathways of tsunamis, and identified the scientific approaches for quantifying these pathways. It has also assessed the feasibility of controlling the risk associated with a tsunami, compared the likelihood and magnitude of tsunami to other environmental risks, and evaluated people’s perception of risk associated with a tsunami and compared that with perception of other risks. Reference list Barrera, JCB, The weakness of the scientific assessments: a praise of silence, November 15, 2009, Dudley, WC & Lee, M 1998, Tsunami!, University of Hawaii Press, Hawaii. Fradin, JB & Fradin, DB 2008, Witness to disaster: tsunamis, National Geographic Society, Washington, D.C. Harvey, T 1971, warning: tsunami - giant seismc sea wave, Popular Science. Vol. 199, No. 6, Pp. 64,65&113. Bonnier Corporation, New York. Kajikawa K 2009, Tsunami!, Philomel Books, New York. Kurita, T, Arakida, M & Colombage, SRN 2007, Regional characteristics of tsunami risk perception among the tsunami affected countries in the Indian ocean, Journal of Natural Disaster Science, Vol. 29, No. 1, pp29-38. Lerche, I & Glässer, W 2006, Environmental risk assessment: quantitative measures, anthropogenic influences, human impact, Birkhäuser, Switzerland. Pedlosky, J 1987, Geophysical fluid dynamics. Springer, Australia. Reddi, LN & Inyang, HI 2000, Geoenvironmental engineering: principles and applications. CRC Press, Australia. Västfjäll, D, Peters, E & Slovic, P 2008, Affect, risk perception and future optimism after the tsunami disaster, Judgment and Decision Making, Vol. 3, No. 1, pp. 64–72. Read More