AN ASSESSMENT OF EXPLOSION SITES :



By Masinde Caleb Juma.

An explosion is defined as a large-scale, rapid and sudden release of energy. This energy propagates as a shock wave through a medium, or in the absence of a material medium, through an electromagnetic field. Explosives have a wide variety of industrial applications such as breaking hard rocks during mining and construction, demolishing defunct buildings, controlling avalanches in the Alps, aiding oil and gas exploration, visual effects in the entertainment industry and lighting up the sky during firework ceremonies.

However, on the flipside, the destructive power of explosives has been harnessed for a negative cause usually in the name of terrorism. Urban regions have borne the brunt of such attacks. One such attack on the seventh of August 1998 in Nairobi took the lives of 218 innocent people and injured several thousand others. Other notable examples of destruction caused by terrorist bombs in the last decade include explosions in the financial center of London, a multistory Jewish community center in Buenos Aires, the Alfred P Murrah federal building in Oklahoma City and the Khobar Towers in Saudi Arabia.

The use of explosives for terrorist purposes (Bombings) account for nearly half (46 percent) of all international terrorist attacks carried out since 1968, a proportion that has rarely fallen below 40 percent or exceeded 50 percent in any year. Few skills are required to manufacture a crude bomb, surreptitiously plant it, and then be miles away when it explodes. These attacks typically involve only one or two persons and, in general, do not require the same organizational expertise, logistics,and knowledge required of more sophisticated operations such as kidnapping, barricade and hostage situations, assassination, or assaults against defended targets. (Center for the Study of Terrorism and Political Violence).

A bomb explosion within or immediately near a building brings catastrophic effects. Recent terrorist attacks against urban buildings dramatically illustrate the influence of bomb placement and building design on the nature and extent of direct structural damage. A bomb's damage to buildings depends not only on the building's construction criteria and the strength of the bomb but also on their location relative to the blast's epicenter. A good case point is the 7th August 1998 bomb attack on the US Embassy in Nairobi, Kenya. Although the main target of the blast was the American Embassy, most of the adjacent buildings such as Ufundi house bore the brunt of this attack in terms of structural failure and its occupants got injuries or worse off paid the ultimate prize.

Due to such disastrous effects, there is need to develop a suitable spatial model that will demonstrate the effects of such a blast in a target's neighbourhood and thence forth answer a number of questions. For example, which buildings are likely to be affected by a terrorist bomb attack based on their spatial distance from the main target structure? Why are some buildings which are far awayfrom the explosion foci damaged more than buildings at the blast's epicenter? What standard should guide insurance premium rates paid by property owners whose structures border potential target sites? What measures should property owners take to protect their lives and investments from sudden destruction? One way of doing this is by using Geographic Information systems (GIS) to carry out 3 Dimensional visualization.

3D mapping/ visualization is a technology that creates three dimensional views of natural and man-made features and realistically represents them on a map for better analysis and decision making. It provides an effective way of presenting large amounts of complex information to a wide audience, including those with no GIS or mapping experience since it allows the user to easily relate the information to reality. Apart from defense, 3D mapping can be applied to a number of other sectors including urban planning, architecture, engineering design, scientific and medical research.