Terrorist Attacks on Low- and High-Density Areas
Jay Manifold speculates about the possibility of a terrorist attack on Kansas City, a very low-density metropolitan area. It's hard to arrange a terrorist attack on Kansas City using methods such as explosions or nerve gas. If the attack method can “live off the land,” on the other hand, its power is proportional to the area, so low density is no defense. At present, the only reliable terrorist attack that can extract resources from its surroundings is arson. Arson is commonly used by the Earth Liberation Front, but it's rarely spectacular enough to make headlines. That can change.
If the terrorists use gray goo as a terrorist weapon, they may prefer to attack areas with more potential food for the goo available. Food sources may include the obvious (gas storage tanks, oil storage tanks, munitions dumps) and also the not so obvious (reams of paper, asphalt roads, nearby trees, or maybe even lawns). If it will release energy when combined with oxygen, it is a potential gray-goo food. A low-density area might still be relatively safe, but only if all the streets are concrete instead of asphalt and if lawns and trees are prohibited.
High-density areas are not necessarily easier targets, even at present. Biological attacks might be less effective in areas with more hospitals. It's probably easier to wash radioactivity from a “dirty bomb” off concrete than out of dirt. The vulnerability of skyscrapers can be reduced by building down instead of building up. For a while, it seemed possible there could be a few survivors in some of the World Trade Center's basements.
In general, there are two types of ways to deal with terrorism: to reduce people's options in the hope terrorists will be unable to carry out their plans or to allow people to foil the terrorists on their own (also known as the pack-not-a-herd principle). Since terrorists depend on surprise, it is impossible to anticipate their every move. We will have to depend on letting people improvise. It is, of course, easier to improvise a response when there are more people around.