China and US at highest risk of damage from Earth Shattering Asteroids
Pastor Dale Morgan
China and US at highest risk of damage from Earth Shattering Asteroids*
* 14:01 27 March 2007
* NewScientist
* David Shiga
The worst places for an asteroid to strike in terms of infrastructure
damage are shown here in red, with the north Atlantic appearing
prominently (Illustration: Nick Bailey et al/University of Southampton)
China and the US are the countries most vulnerable to damage from future
asteroid impacts, according to preliminary new research. Sweden also
ranks surprisingly high in this first attempt at quantifying the risks
of impact effects, such as tsunamis, on individual nations.
Scientists have been able to simulate the propagation of tsunamis,
earthquakes, and debris from virtual asteroid impacts for years. But
previously, there has been no software to quantify the human toll on
particular countries.
Now, researchers have combined impact effects with data on population
density and infrastructure location in a computer model to produce the
first global ranking of countries based on their vulnerability to impact
damage.
Nick Bailey of the University of Southampton, UK, led the development of
the new software. The team used the model to simulate thousands of
impacts at points all over the Earth, building up statistics on which
countries tended to be the worst affected the most often.
They considered a range of impact energies corresponding to asteroids
between 100 and 500 metres across, striking with typical solar system
speeds of about 20 kilometres per second.
Earth at night
The team focused on smaller asteroids because they hit the Earth more
frequently. An asteroid a few hundred metres across hits the planet
about once every 10,000 years, on average, while those larger than 1
kilometre hit only every 100,000 years or so. Small asteroids are also
harder to spot. "We're more likely to be hit by one without much
warning," Bailey told New Scientist.
Using maps of population density, the researchers charted the places
likely to suffer the most casualties. As might be expected, countries
with large coastal populations turned out to be most vulnerable, with
China, Indonesia, India, Japan and the US in the top five spots.
Determining the economic damage to different countries was more
difficult. The researchers made this part of their assessment based on
estimates of the amount of infrastructure located in different parts of
the world.
Using images of the Earth from space showing the distribution of light
from artificial sources, they assumed the brighter places were more
built up. Then 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 US faced the worst potential losses, perhaps not surprisingly, since
it has a lot of infrastructure on coastlines facing two different
oceans. China was second, followed by Sweden, Canada, and Japan.
Smaller impacts
Sweden’s third highest rank is somewhat of a surprise. Bailey notes that
its well developed infrastructure is more vulnerable to tsunamis than
that of other European countries like Germany, since it has a long
coastline.
The researchers also produced maps showing the worst possible places on
Earth for an impact to occur. The Pacific coast of Asia shows up as an
especially bad place in terms of producing casualties. Impacts in the
north Atlantic Ocean, which can send tsunamis to both Europe and North
America, tend to produce particularly high infrastructure losses.
The biggest source of uncertainty for the results 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 – a scenario not considered in the model, Bailey says.
Clark Chapman of the Southwest Research Institute in Boulder, Colorado,
says more research along these lines is needed to better understand the
nature of the asteroid hazard. "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," he told