Physical Geography - Synoptic

Nicholas  Drake

24 April 2002

 

The frequency and distribution of a hazard such as an Earthquake is constant throughout the world. This can be explained through the investigation of plate composition, plate tectonics and they way in which Earthquake waves ‘move’. Although from the map shown below, there are areas that may be particularly more prone to powerful and frequent Earthquakes.

 

However although the location of Earthquakes may be concentrated along particular belts as shown above (which co-incidentally align perfectly with plate boundaries) what does vary between MEDC’s and LEDC’s is the IMPACT that these Earthquakes have upon the area.

For instance, during the October of 1985, Centered south of San Francisco, the Loma Prieta earthquake which measured 7.1 on the Richter scale devastated San Francisco. The quake shook the entire San Francisco Bay Area, causing extensive damage to older buildings in the Marina District. The quake also caused the collapse of a highway in Oakland and part of the San Francisco-Oakland Bay Bridge.  The point of mentioning this example was that although it’s RS rating of 7.5 is large, but not technically of a cataclysmic scale, why did it cause so much damage?

The answer to this question lies in the fields of prediction and reducing the impact of any Earthquake or hazard.

Buildings are built to withstand the downward pull of gravity. Earthquakes push on a building in all directions--up and down, but most of all, sideways. A safe building is one that can withstand the sideways push.

A safe building is built on a firm foundation. The foundation should be solid with a continuous perimeter.

A safe building is built of strong materials. Damaged concrete and rotten wood undermine the integrity of the building

A safe building will also include features such as triangular shaped structural frames as in the Transamerica Pyramid in San Francisco, concrete counterweights as in the New York World Trade Centre buildings or Spring like shock absorbers as in research projects in Japan.

 

Within an LEDC, one may find that the Short term effects of a natural disaster may be similar to those experienced by an MEDC. Such effects may include: Fire (1903 Tokyo fire), Buildings collapse (Mexico city 1985), Landslides (Mexico city 1985) and less commonly soil liquefaction.

However, the long term effects of natural hazards can be far more devastating for an LEDC than the actual event itself. For instance, after an Earthquake many thousands of aftershocks may be registered, gas lines may be ruptured hindering efforts to stem fires, water pipes may break cutting off a clean water supply aiding the growth and possibility of an epidemic and disease either water-borne or from stale food. Another major problem in an LEDC is the cost both in terms of actual building cost but probably more costly is the loss of business across the country because factories, offices have been destroyed. For a struggling country such as Mexico which already has a national debt so high it struggles to pay of the interest on the debt each year, it will reduce the amount of GNP and therefore after a long and complicated process mean that the possibility for external investment in Earthquake research / prediction or prevention has to be ignored. This therefore leads to a continuing downward spiral in which the average person continues to pay in intangible terms whilst not receiving any more protection.

 

As with any of these structural aids to reduce the impact of Earthquakes, these benefits will only be of gain to inhabitants of MEDC’s, these expertise, technology but most significantly the finance will never be available to provide these countries with enough money for Earthquake prevention / prediction research.

 

The majority of deaths and injuries from earthquakes are caused by the damage or collapse of buildings and other structures. These losses can be reduced through documenting and understanding how structures respond to earthquakes. Gaining such knowledge requires a long-term commitment because large devastating earthquakes occur at irregular and often long intervals. Recording instruments must be in place and waiting, ready to capture the response to the next trembler whenever it occurs. The new information acquired by these instruments can then be used to better design earthquake-resistant structures. In this way, earth scientists and engineers help reduce loss of life and property in future earthquakes without knowing exactly where they may strike.

 

Although frequency occurs almost the same, it is money and investment which determines the overall relative destructive capabilities of Earthquakes and hazards in general.

 

 

 

We must realise that although every day we continue to research new and improved methods of Earthquake and hazard prediction, we will never be able to predict a natural event with enough time to prepare or prevent any fatalities or building damage.