“Those elements in physical environment harmful to man and caused by forces extraneous to him”. Definition of natural hazards, by I. Burton and R.W. Kates (1964).
A hazard only becomes a hazard if it affects, or threatens to affect people. It is essentially man centered. If no people are at risk, it is not a hazard. (See fig 1.0)
The more people living in hazardous environments, and the higher the level of development, the more damage caused by hazards.
“Venerability to any kind of hazard is essentially determined by poverty”. Maskney (1989).
Natural hazards happen because the Earth is always moving, and the tectonic plates are constantly grinding next door to each other. Where the plate boundaries lie, most natural hazards occur, such as Earthquakes and Volcanic eruptions.
Death rates from natural hazards and disasters seems to be increasing. This is due to population growth, economic growth and the increasing use of hazardous environments.
In the 1970’s and 1980’s about three million people were killed by natural hazards and they affected a further 820 million people. They have also cost the global economy an estimated US $40 billion in losses and US $15 billion in relief and rehabilitation.
Natural hazards claim more lives in poorer countries with over 90% of deaths occurring in developing countries. The impact of hazards in developed countries can have a greater economic cost but may cause fewer deaths.
People not using the land in a decent manor can intensify hazards. An example of this is an avalanche. Ski resorts (such as those in the Swiss – Austrian Alpes) all have areas which are out of bounds, where the snow is not stable enough for skiing, and yet people abuse this. The consequence is an avalanche.
Avalanches can happen wherever there is snow lying on ground of sufficient angle. Increased popularity of winter climbing and hill walking, along with the growth of interest in off piste skiing means that more are at risk. Each year adds to the list of injuries and/or fatalities. Many of these accidents would have been avoidable, given greater care or knowledge, or if the victims had considered that an avalanche might be possible.
Avalanches can be specifically defined as mass movement hazards and the reason for this is obvious – movement is the basic reason for the hazard to humans. They occur when the downward force becomes larger than the upward slope. The increase in mass, and the force of gravity, can increase the danger of an avalanche. The most important triggers of an avalanche are; heavy snowfall – due to increased mass, Rain or thaw – decreasing friction, or an increase in the dynamic loading – meaning a moving mass such as a skier. (See fig.1.1)
When avalanches occur near humans there is always the potential for death and destruction. Anyone on the slopes in the path of an avalanche has little, if any, chance of survival. Victims of avalanches can often be buried just a few feet below the surface and not escape, as the snow becomes extremely dense due to its fall.
In 1916 during the First World War, over 100 avalanches killed about 18,000 soldiers as they fought on the slopes.
It is not only those who are on the slopes when an avalanche occurs that are in danger. Whole villages can be consumed. In Switzerland, the country with the highest number of deaths due to avalanches in the world, many villages have been destroyed several times over.
One avalanche in an LEDC that caused catastrophic destruction was in Peru on the Nevado Huascaran. In 1970 an earthquake that measured 7.8 on the Richter scale sent approximately 50 million cubic metres of snow and ice to the bottom of the valley in 3 minutes. By the time the snow came to rest 10 miles from its starting zone it had killed around 18,000 people.
Another hazard, in which people can be blamed for the intensity of the impact, is flooding. The higher the economic development within an area, otherwise known as an MEDC, the greater the impact. This would mean that less economically developed countries are at less risk from flooding – But this is not true. Countries such as Zambia, in Africa have over used the land, and it has become infertile. This makes it impossible for water to infiltrate, causing flooding, and no crops.
In MEDC’s such as the U.K, flooding is often, but not always as fatal as in MEDC’s. This country is developed, and therefore has tarmac streets and drainage systems for excess rainfall. This strategy, however, does not always work. The drains can get blocked easily, and cannot cope with the amount of precipitation – caused by tarmac, which does not let water infiltrate, causing over land flow and flooding. Vegetation is also destroyed in order to build houses and other human needs – causing less water to be taken in by the ground. The flooding in the U.K is helped by human development on flood plains. People can be part of the blame in this quasi natural hazard.
Earthquakes are another type of natural hazard, which the impact can be influenced by humans. An earthquake in an MEDC such as Kobe, Japan can have a much greater impact than an earthquake in India, for example. This is because of the level of economic development. As more buildings and bridges are present in Kobe, more damage to them is made, and damage of buildings and bridges kills people in the densely occupied city, Such as those in the buildings and those in their cars.
17TH January 1995, 75,000 buildings were destroyed and nearly 6,000 people killed in an earthquake 7.2 on the Richter scale. The damage was put at ï¿½60 billion. Most deaths happened in the old residential areas, where buildings had been constructed before the introduction of designs to help withstand earthquakes. Although many newer buildings in Kobe were built to withstand earthquakes measuring up to 8.3 on the Richter scale, some of them still collapsed. This shows that even with the most developed countries and lots of money, still man cannot stop a hazard from occurring, and affecting their lives. (See fig.1.2)
Fig.1.2 Kobe earthquake, 1995
An earthquake in an LEDC would not have the same impact as the Kobe earthquake, simply because it is not as developed, and there are less buildings – less damage to buildings, and less deaths and injuries. Many thousands of people can be killed and injured where proper earthquake warnings; building precautions and response plans are not available.
LEDC countries that have been devastated by earthquakes include India where, in 1737, around 300,000 people were killed by an earthquake. The largest earthquake ever to be recorded occurred on May 22nd 1960 in Chile with a magnitude of 9.5 on the Richter scale. Shock waves caused destruction that spread over 90,000 square miles, destroying 50,000 homes and killing 6,000 people
The level of response from each individual hazard area can determine human impact on hazards. Some simply accept they live in a hazardous area and do nothing, or maybe move to a less prone area, whereas others try and respond by controlling it.
Hazards are inevitable but controllable – modify the cause prevention. Plant trees, build reservoirs etc.
Hazards are inevitable but effects can be controlled – Reduce damage potential by early warning systems, Insurance etc.
These responses can make things worse, depending on when they take place. If action is taken during an event, it influences the amount of damage and people killed. If it is between the events, then preparation can be planned, and less people could be killed in the actual event.
From this essay I have found out that humans affect the impact of some natural hazards, and in some cases also the causes of hazards. Living on a plate boundary is a choice, and natural hazards have to be accepted as part of daily lives, but humans have to build – and when they do, more fatalities occur when hazards occur. Countries not situated on plate boundaries are still at risk of natural hazards, such as flooding etc, but the impact is determined by the level of development. MEDC’s have the ability and budget to put money into predictions of natural hazards, and some methods have helped, but natural hazards are present all over the world, and no matter how man tries to prevent damage to their lives, they will never be stopped.