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The natural hazards

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    The natural hazards caused by plate tectonics are more a result of human factors than physical ones. Discuss to what extent do you agree with this statement? [40 marks] A natural hazard is a threat of a naturally occurring event that will have a negative effect on people or the environment. The Earth’s lithosphere (crust) is divided into tectonic plates which are constantly in motion due to the convection currents caused by heat cycles in the mantle, driven by radioactive decay in the Earth’s core. Natural hazards caused by plate tectonics are earthquakes, volcanic eruptions (and tsunamis – secondary effect of the first two). It is important to understand that there is a clear division between a natural hazard and a natural disaster. A good example would be the 1906 San Francisco earthquake which killed about 3000 people and was a disaster, whereas the population of 342,782 people (San Francisco 1900 Census) living on a fault line was a hazard (NB. not naturally, but actually voluntarily occurred hazard).

    Therefore it could be argued that there is no such thing as “natural hazard”, because people choose to place themselves in areas which potentially present a risk, therefore it doesn’t naturally occur and therefore such phenomena should be correctly called “anthropogenic hazards”. Most hazardous processes are primarily geologic processes. Geologic processes effect every human on the Earth all of the time, but are most noticeable when they cause loss of life or property. If the process that poses the hazard occurs and destroys human life or property, then a natural disaster has occurred. Volcanic eruptions, earthquakes and tsunamis are classified as hazardous only because they negatively affect human beings. In fact, there would be no natural disasters if it were not for humans. Without humans these are only natural events. Anthropogenic hazards occur as a result of human interaction with the environment. These human interactions can further be classified as vulnerability to hazards – the way a hazard or disaster will affect human life and property. Vulnerability to a given hazard depends on: proximity to a possible hazardous event; population density in the area proximal to the event; scientific understanding of the hazard; public education and awareness of the hazard; existence/non-existence of early-warning systems and lines of communication; availability and readiness of emergency infrastructure; construction styles and building codes; cultural factors that influence public response to warnings. In general, less developed countries are more vulnerable to natural hazards than are industrialized countries because of lack of understanding, education, infrastructure, building codes, etc. Poverty also plays a role – since poverty leads to poor building structure, increased population density, and lack of communication and infrastructure.

    Human intervention in natural processes such as development and habitation of lands susceptible to hazards, for example, building on volcanic slopes subject to volcanic eruptions (e.g. City of Pompeii on Mount Vesuvius), can also increase human vulnerability to “natural hazards”. There are two types of volcanic and earthquake hazards. Primary – occur as a result of the process itself; secondary – occur only because a primary hazard has caused them. The primary volcanic hazards include pyroclastic flows, air-fall tephra, lava flows and volcanic gases. The secondary volcanic hazards include ground deformation, lahars (mudflows), landslides and possibly tsunamis in ocean floor volcanic eruptions. The primary earthquake hazards include the effect of ground shaking and ground displacement. The secondary earthquake hazards include flooding, infrastructure collapse, fire and possibly tsunamis in ocean floor earthquakes. All these processes are hazards because they may result in death and man-made constructions’ destruction.

    However, it is important to understand that in most cases all of these hazards do not occur in one event and because there are so many different ones, this essay is going to focus on two case studies and explore hazards specific to them. In 1980, a major volcanic eruption occurred at Mount St. Helens, a composite volcano located in Washington, in the United States, positioned at the top of a boundary between Juan de Fuca and the North American plates. Prior to the event there were two-month series of earthquakes, caused by an injection of magma at shallow depth below the volcano that created a huge bulge and a fracture system on the mountain’s North Slope. The natural hazards that occurred as a result of the eruption were landslide and debris avalanche, lateral blast, lahars, eruption column and cloud and pyroclastic flows. The impacts of 57 deaths and $1.1 billion in property damage occurred due to physical factors (i.e. geological processes were responsible for carrying out this damage), but this would not of happened if in the first place there were no human factors (i.e. humans remaining in the evacuation zone and infrastructure built on potential eruption-affected land). Therefore this natural disaster (primarily a hazard) was a result of human factors and not physical ones. The key reason for humans living close to volcanoes since the early ages was due to the volcanic ash which has high nutritional values for crops. Back then people had no geographical and, what’s more, geological knowledge, so they were not aware of tectonic plates and their consequential processes. Arguably, this is the only point in history of human beings where natural hazards could potentially be described as caused by both physical and human factors, because people did not possess any information on how to avoid these geological processes.

    So, primarily, groups settled where they could grow crops and since then (and until the present day) people just carried on expanding the infrastructure on an already inhabited area and not bothering to move, thus forming major cities, many of which consequently appear on plate boundaries and therefore are located in earthquake and volcanic activities hazard zones (please see map below). Now, this is where the statement comes into being hundred per cent correct, because this time (starting from 18th century when Industrial Revolution has been the driver for the development of infrastructure) people already possessed the geographical knowledge of plate tectonics (e.g. the Continental Drift theory was put forward by Abraham Ortelius as early as 1596). What’s more, this knowledge gave them the chance to choose between safety and risk. By choosing to expand infrastructure in hazardous areas it is obvious that the human kind was (and still is, seeing as their choice hasn’t changed) stupid enough to choose the risk option. Many people who are born into such “risk” cities adopt an acceptance approach and agree to the risks because the advantages of living in that area are greater.

    For Mt St Helens region, local business financially benefit a lot from more than 300 000 tourists visiting the volcano each year, therefore for them, the risks of infrequent volcano eruptions do not dominate over a stable source of good income. Another problem, seen especially in MEDCs, is that people become too contingent on manmade structures and adopt an adaptation approach where they rely on prediction, prevention and protection, and therefore carry on living in danger zones at higher risk of “natural hazards”. However, in Mt St Helens case, people were warned for nine months in advance (and many left the area), however, those who stayed caused this geological event to become a natural disaster by allowing it to negatively affect them. Lahars, landslides and debris avalanches all represent a fast moving big mass of naturally-occurring material which is regarded as a hazard only because people get in its way. If however it was not for human factors (i.e. human physical lives, manmade infrastructure and belongings) these natural events would not be classified as hazards. Similarly, naturally-occurring Sulphur dioxide gasses emitted during volcanic activity only cause irritation in eyes, nose and throat, because these human parts were next to the eruption in the first place. The argument is that knowing the volcano is about to erupt, it is solely humans’ responsibility for any “natural disaster”, because they are given a chance to escape it. On 26th of December 2004 an undersea earthquake occurred at 00:58, with an epicenter off the west coast of Sumatra, Indonesia.

    The cause was the sudden move in jammed subduction of the Indian Plate by the Burma Plate triggering an earthquake which resulted in a 30m tall wave, known as the Indian Ocean Tsunami – one of the deadliest natural disasters in recorded history. Tsunamis only have one natural hazard – the sheer power of the moving wave which drowns people and destroys everything on its way. Being a frequent result of an ocean floor earthquake, tsunamis can be predicted and therefore if people cannot prevent, they can prepare for it (by leaving the region or climbing hills) and warn others. This is why Indian Ocean Tsunami illustrates perfectly how human factors are the key causes of natural hazards and disasters. The death toll of over 280,000 people could have well been avoided or at least been much smaller if there was a warning system in place. Unfortunately this was not the case, even thought Indian Ocean is located on the Pacific Ring of Fire and is regarded as an area with the most frequent earthquakes, people of India, Indonesia, Malaysia, Maldives, Myanmar, Somalia, Sri Lanka, Omar and many other countries were taken by a complete surprise when they saw a tsunami wave.

    However it should be said, that despite the fact that humans are the reason for tsunamis ruining the manmade infrastructure and it could be argued that knowing that this will happen, people should not build and live on coastal zones, it is a fact that with a current (and rapidly growing) population of over 7 billion it is simply not possible to avoid this development, because there is not enough inland space. Consequently, the looking at tsunamis in support of the proposed statement will end up in moral arguments on whether human population puts itself at risk of “natural hazards” by actually being so large. Following from that it can even be said that there would not be any problem at all if humans weren’t there in the first place; however human kind’s existence is not the aim of this discussion, especially as the same processes driving tectonic activity have created humans. In addition, in this particular case it has been argued that human factors did play a major role in this natural hazard. Humans destroyed the coral reefs (making way for shrimp farms, shipping and other vital economic activities of this region) which exacerbated the destruction caused by the tsunami. In comparison the Surin Island chain of Thailand’s coast have had much smaller impact from the tsunami because the wave rushed against the coral reefs, lessening its impact of sheer water. Similarly, the removal of coastal mangrove trees and coastal sand dunes on the coast of Indonesia to make way for beach residences, have increased the force of the tsunami, because the wave had less friction area to lose its power before hitting the buildings.

    There is a trend, that major hazard zones tend to be in big cities in EDCs, where population densities are highest but the developing infrastructure lacks the sufficient protection in place to support its magnitude (i.e. skyscrapers built at the beginning of industrialization in the 20th century using primitive construction techniques, which have not been reconstructed to meet the earthquake-proof regulations with nanostructures). As a result of creating such vulnerable environments humans put themselves at a greater risk of natural hazards, therefore it does not matter as much what the natural factors are, as much as how manmade structures (human factors) will withstand to them and how much further damage (collapsing and trapping people in debris) will they do. Indian Ocean earthquake mostly affected LEDCs where there is less money available to carry out prediction, protection and prevention, as a result people were not able to take advantage of recent technologies and were adversely affected by the natural hazard, but once again, it could have been avoided if they were made aware by MEDCs. To summaries this discussion it needs to be said that of course both natural and human factors contribute to “natural hazards”, it is actually more of an argument which one comes first and therefore plays a bigger role in the primary causation. The conclusion of this essay is that there are no such occurrences as “natural hazards” because it is incorrect to place these two words together. It is either natural geological processes or hazards created by humans, because these events only present a risk when they have an impact on human life. Furthermore, there is arguably no such thing as “physical factors” either, in fact, what is actually supposed under this phrase are “geological processes” which have been taking place before human kind has appeared on Earth. This leaves the discussion to say that in the current world humans have enough knowledge and information about plate tectonics, that there should be no hazards present from them; however human beings choose to put themselves at risk by ignoring this acquaintance. Therefore, perhaps the statement should be rephrased into: “Human kind’s risk taking and hazard creation from geological processes of plate tectonics are more a result of human stupidity and tendency to get away with calling them natural hazards”.

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    The natural hazards. (2016, Oct 27). Retrieved from

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