Too much development?

Mar 29, 2007 07:46 GMT  ·  By

Early in the morning of June 30, 1908, in the Tunguska region of Siberia about 1,000 km (600 miles) north of Irkutsk, an asteroid about 60 meters (200 ft) in diameter entered the Earth's atmosphere, resulting in an immense explosion, centered about 8 km (5 miles) above the forest below. Trees were flattened over an area about 50 km (30 miles) in diameter, several times larger than the area around Washington, D.C. It exploded with energy in the range of a modern nuclear missile warhead, about 10 megatons, or about 500 times the energy of the Hiroshima atomic bomb.

While there were few, if any, casualties from this event, if such an event were to occur in a more populated area it would be a major natural disaster, comparable to a major flood, earthquake or volcanic eruption.

Scientists have recently been able to simulate, by employing a new highly complex software, thousands of impacts at points all over the Earth, building up statistics on which countries tended to be the worst affected the most often, and Nick Bailey of the University of Southampton, UK, led the development of the new software.

An asteroid a few hundred meters across hits the planet about once every 10,000 years, on average, while those larger than 1 kilometer hit only every 100,000 years or so the team focused on smaller asteroids between 100 and 500 meters across, striking with typical solar system speeds of about 20 kilometers per second.

Employing maps of population density and estimates of the amount of infrastructure located in different parts of the world by using images of the Earth from space showing the distribution of light from artificial sources, they simulated the propagation of tsunamis, earthquakes and debris from a wide variety of impact locations to rank countries on the vulnerability of their infrastructure.

The results were worrying, as the US faced the worst potential losses, since it has a lot of infrastructure on coastlines facing two different oceans. China was second, followed by Sweden, whose well developed infrastructure is more vulnerable to tsunamis than that of other European countries like Germany, since it has a long coastline, and then Canada, and Japan.

Another potential threat is the possibility that a single incoming asteroid might not make it to the ground intact, fragmenting in the atmosphere instead to produce multiple, smaller impacts on a larger area.

The conclusion of the study was drawn by Clark Chapman,of the Southwest Research Institute in Boulder, Colorado, "We need to understand the potential risks on a country-by-country basis, since individual countries may have different vulnerabilities to this hazard as well as different capabilities to deal with it."