• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

The Global Distribution of Geophysical Hazards

Extracts from this document...


The Global Distribution of Geophysical Hazards Fig.1 Global distribution of highest-risk disaster hotspots by hazard type Fig.1 shows the risk to human populations from naturally occurring hazards. It does not therefore map the actual global occurrence of hazard types but gives a rough outline of the distribution given that humans populate most parts of the world. Discrepancies, however, are noticeable; for example, although there is a high risk of death by drought in Africa the risk of death is not great in central Australia. The map implies that there is a general north south divide where mortality rates are concerned; rates are much higher in LEDCs (South) than MEDCs (North). The two biggest killers are drought and hydro-related hazards. Africa is the region most affected by drought, particularly in areas around the equator e.g the Sahel covering Ethiopia, Niger etc. Flooding affects mostly coastal areas, particularly those in India, Bangladesh, eastern China, and the Caribbean. These areas are also especially vulnerable to monsoons, hurricanes and storms. The areas at highest risk from multiple hazards are disaster hotspots such as Indonesia, India, the Philippines, Japan, and west coast of Mexico/California; the circle of coastal regions around the Pacific ocean known as the Ring Of Fire. ...read more.


A small percentage of volcanoes occur on constructive margins, namely the North Atlantic ridge which produces gentle shield volcanoes. Volcanoes can also occur inside plate margins over areas called hotspots. One can see that Africa's volcanoes are mostly within the area of the plate, and are products of hotspots rather than plate collision. Fig 4 also shows the distribution of earthquake zones. Earthquakes can occur within any plate margin but there are three main fault lines between them that account for most of the world's volcanoes; the Western Pacific, the Eastern Pacific, and the Southern Eurasian. Of these the destructive boundaries of the Pacific plate account for the worst and most destructive earthquakes. This map clearly shows that the distribution of volcanoes follows the earthquake zones in America and East Asia. Roughly 2/3 of volcanoes therefore occur in earthquake zones. The 'middle' earthquake zone follows the boundaries between the southern Eurasian plate and the Iranian, Indo-Australian, and African plates. It is by far the most active earthquake zone on earth but does not have any volcanoes. Fig.5 Seismic risk Fig.5 gives more information about the risk of an earthquake occurring. One can see in both Figures 4 and 5 that although the pacific seismic zones are long and belt-like the area squeezed between the Arabian Peninsula and the Himalayas is both long and wide; Iran and Iraq are particularly badly afflicted. ...read more.


The second most severe volcano disaster in terms of human fatalities was in Cameroon which lies, like most of Africa's volcanoes, on a hotspot. Mt Cameroon is the largest and most frequently erupting volcano in Africa. Between 1975 and 2000, the volcano erupted 3 times. Indonesia boasts the largest concentration of active volcanoes (76!) of any country and has a relatively high mortality rate related to volcanoes. Between 1975 and 2000 Indonesia suffered volcano-related deaths in 9 out of the 26 years. It also has a recorded history of 1,171 eruptions which is only just exceeded by Japan with 1,274. Together, they share 1/3 of the world's recorded volcanic eruptions. In conclusion: I have shown that those countries with Pacific coastlines are at by far the highest risk from geophysical hazards. The subduction taking place around the Pacific rim causes both frequent earthquakes and frequent volcanic eruptions. By contrast the collision between the Eurasian plate and those colliding with it from the south is the cause of widely distributed earthquake-related hazards, affecting continental peoples more severely than elsewhere in the world. This area however has a relatively low occurrence of volcanic eruptions. Hydro-meteorological hazards remain, however, the most destructive of all natural disasters throughout the world. Of all human populations the Chinese nation is the worst affected by natural hazards, both geophysical and hydro-meteorological, in terms of sheer number. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Hazardous Environments section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Hazardous Environments essays

  1. Marked by a teacher

    The number of fatalities that result from volcanic and seismic natural hazards is related ...

    4 star(s)

    Irregularities on faults that are moving past cause frictional build up, when their force against one another build to a high enough degree they lurch past one another and the pressure is released as seismic waves causing an earthquake. A similar process occurs at submergent plate margins.

  2. Marked by a teacher

    Explain the increasing frequency of Hydro-meteorological Hazards.

    3 star(s)

    An example of this happening is in Scarborough, 1993, a hotel on the coastal resort collapsed, as the ground beneath it was turned into mud. Global warming does not affect the total amount of rain falling on earth, but it can have huge impacts on local climates by exaggerating pre-industrial patterns of rainfall.

  1. Describe and explain the global distribution of volcanoes and earthquakes.

    These follow two main sets of lines, the first being shallow earthquakes, that follow the line of sub-oceanic ridges. The second set, mostly deep earthquakes, follow the lines of subduction along deep-sea trenches. Earthquakes are known to induce an eruption (as in the case of mount St Helens in 1980).

  2. Los Angeles: An Area of Multiple Hazards.

    The local authorities say they are attempting to help the community but they feel the people must do more to help themselves. They even threaten withdrawing welfare payments after two years without work. Residents often believe that they are being targeted for this bad treatment because they are from racial

  1. Compare and contrast the Philippines and Californian hotspots, giving an opinion as to which ...

    The government can only spend so much on risk management as there are so many other more pressing matters that must be prioritised. Governments of poorer countries often have to take risks and as high magnitude hazards are generally quite rare, the Filipino government has to put other problems higher up the list.

  2. California and the Phillippines - Hazard Hotspots and Human Management of Risks

    Hazard 1 Earthquake: Philippines The Philippines has been an earthquake hotspot for years this is because: * The Philippine plate and the Eurasian plate can become locked together as one moves under the other. This causes pressure to build up.

  1. To what extent is magnitude the main factor to influence the type and level ...

    This significantly lower impact was largely due to the residents of Chile perceiving there to be a hazard as Chile is prone to earthquakes. This meant that the Chilean government taking this into account and investing in earthquake preparedness schemes which resulted in many of the people trapped in homes

  2. The World Distribution of Population is as important as the world distribution of areas ...

    links between the two variables needed to calculate risk are impossible to ignore.   From the detailed comparison of the maps above, the West coasts of South America and North America and the Ring of Fire region have both density of volcanoes and people; strong positive correlation between the two variables implicit of how both are necessary in hazard prediction.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work