Another type of natural hazard and also related to tectonics are Earthquakes. These are caused by the plates either rubbing parallel against each other, or pushing into one another. The energy stored up underneath the Earth’s crust is released causing a movement in the plates as the energy is transferred into earthquake waves.
These waves travel for miles and can cause considerable damage to buildings and eventually human life. One such earthquake occurred in 1995 in the city of Kobe, Japan. As Japan is situated on the edge of the Eurasian Plate, it is prone to major earthquakes. On January 17th 1995, the Japanese city of Kobe was hit by Japan’s largest earthquake since 1923. Many of the population were asleep at the time. Because Kobe was only 20km away from the epicentre (place of origin) this meant that the damage that was going to be caused would be in great numbers. Because a huge amount of central Kobe was built on soft rocks that are easily moved (around the port and harbour area) as the earthquake hit, this soft rock (actually much of it reclaimed), turned into practically liquid, giving way to the foundations of the buildings allowing them to topple. More than 102,000 buildings were destroyed in the earthquake. This left some 300,000 people homeless, and ended 5100 lives. In total creating a $150 billion clean-up bill all in just 20 seconds of tremors, therefore being one of the most expensive disasters in modern history. This bill is only taking into account the cost of state-owned buildings and services, and not including the loss of private property of the residents. A lot of damage to the infrastructure of the city, like transport systems, gas, water and electricity made it hard to re-build quickly and save lives. This is an example of a disastrous hazardous environment, where almost all criteria for an area to be classed hazardous were met, with loss in human life, property and wealth.
One of the products caused by these tremors along the Earth’s crust are Tsunamis (a.k.a tidal waves). Earthquakes that happen below or on the ocean floor causes disturbances and. The wave is carried for miles, and the further it travels to land, the greater and more powerful the wave. In the deep ocean, their length from wave crest to wave crest may be a hundred miles or more but with a wave height of only a few feet or less. They cannot be felt aboard ships nor can they be seen from the air in the open ocean. In deep water, the waves may reach speeds exceeding 500 miles per hour. Tsunamis are a threat to life and property to anyone living near the ocean. For example, in 1992 and 1993 over 2,000 people were killed by tsunamis occurring in Nicaragua, Indonesia and Japan. Property damage was nearly $1 billion. Large tsunamis have been known to rise over 100 feet, while tsunamis 10 to 20 feet high can be very destructive and cause many deaths and injuries.
Tsunamis are not only caused by earthquakes, but also by a number of other things, like meteors and underwater landslides, all creating tsunamis. One example happened 65 million years ago, with the meteor that made the dinosaurs become extinct. The meteor that crashed into the Yucatan Peninsula of Mexico creating a tsunami that deposited sediment along the Gulf of Mexico and the United States. Although Humans were not around, it wiped out the dominant species on the Earth, and as we are the dominant species today, the same thing could happen to us.
In Mid-country USA, at around April-July is Tornado season. They are very common in the US and also in various other countries around the world.
Tornadoes are created when hot air from the south meets with cold air from the North. In the US, the warm air currents from the Gulf of Mexico and the cold air currents from Canada up north provide these two factors.
Thunderstorms draw in warm, moist air. This air rises within the storm, as this hot air rises it reaches a point at where it condenses into rain. This sets up an opposing motion: cool downdraft. Changes in wind speed or direction at higher altitudes (called wind shear) can join together the cool air and warm air in a horizontally spinning tube. If more wind tilts this tube so that one end touches the ground, a tornado is born. An example of the damage that can be caused by tornadoes is that of the massive outbreak of 1974. The outbreak lasted 16 hours and produced a total of 148 tornadoes across 13 states from Illinois, Indiana and Michigan and south through the Ohio and Tennessee Valleys into Mississippi, Alabama and Georgia. This killed a total of 315 people and injuring over 5000. One of the most notable tornado of this outbreak was one that moved to the town of Xenia in Ohio. It destroyed much of the town, including the town square and high school, killing 35 people.
Although I have only spoken of a few hazardous environments, there are plenty more that exist, one way in which we can look at these and use them is by classifying and assessing them, the vast majority of these hazards are natural, some are not, and are influenced by human behaviour and interaction with the environment. Examples, like settlements with impermeable surfaces can later lead to flash flooding. Cultivation and agricultural practises can also contribute to flash flooding and landslides.
Natural hazards can be classified by the principal causal agent:
Geophysical
Climatic & Meteorological Geological &
Snow+ Ice, Geomorphological
Droughts, Avalanches,
Floods, Earthquakes,
Frosts, Erosion (inc. Soil, shore,
Hail, & beach erosion)
Heat waves, Land slides
Tropical Cyclones, Shifting Sands
Lightning Strikes + Tsunami
Tornadoes, Volcanic Eruptions
And, Fires.
Biological
Floral Faunal
Fungal diseases, e.g. Bacterial + viral diseases,
Athlete’s foot, Dutch elm disease, e.g. Influenza, Malaria,
Wheat stem rust. Smallpox, rabies,
Infestations etc. Infestations, e.g. rabbits,
Weeds, phreatophytes,
Water Hyacinth,
Hay Fever,
Poisonous plants. Termites
Venomous animal bites,
Locusts
Some natural hazards are considered as catastrophic, these take place quickly and causes sever damage to human life, wealth and property. There is little warning and so limiting the damage cannot be done. Events such as Earthquakes or Flash floods are examples and are classified as “Rapid Onset Hazards”
“Creeping Hazards” are hazards that take place over a long period of time. For example droughts, these can last for a period of up to 10 years or so.
Because there is warning, many things can be done to help, e.g. international food and medication aid. Although this is true, many droughts occur in LEDCs where aid is hard to be distributed and is limited.
Hazards are can be classed as high risk or low risk. The high-risk hazards are those that are distributed in highly populated areas, simply because there is more chance of loss of life and damage to property. The earthquakes of San Francisco are classed as high risk, as it is a large and densely populated urban area, rich with property, human life and wealth.
Low risk hazards are ones that take place in remote areas, but still in some way pose a threat upon human interests. For example, the tsunamis of Alaska, although damage was still done, it was very limited, as this part of the world isn’t hugely populated, so the risk of a lot of damage is low. On the other hand, if a tsunami hit the eastern coast of Japan, which is often does, then this is a high-risk hazard, as the urban areas of Japan are one of the highly dense in the world, with Tokyo being one of them.
The factor of whether it being a high or low risk hazards also determines the amount of money spent on defence and prevention schemes, such as buildings in Japan and San Francisco (two cities prone to Earthquakes), having foundations that can withstand the tremors, and limiting the damage. In an ideal world, this would make sense. Unfortunately, money is the important factor here. A huge number of disasters happen in LEDCs where the funding for aid, defence and rebuilding is not always available.
Of course not every hazard happens on a set timing. Many have periods of centuries before a reoccurrence, whereas some only have years. It depends on the frequency of the hazard as well to see whether it is a high-risk or low-risk hazard to mankind. Giving examples, tornadoes in the central states of the US happen annually and it is obvious that they pose more threat than a massive volcanic eruption that happens every 100 years. We have time to re-build and learn about the flaws with a hazard that happens every 100 years, yet one that happens every year, money must be invested in order for man to survive in that area, and not be killed off by the reoccurring disaster.
In conclusion there are a number of hazardous environments that affect daily lives of humans all over the world, be it as small as hay fever, to as big as a tsunami. The unfair distribution of money seems to determine which areas of the world are more “safe” from these hazards but, the question that is in my mind, is whether can we survive this never-ending battle against nature?