Smaller cities which are dependent on nearby larger cities for their internet connectivity would be hardest hit:

The biggest impact would be felt in the small and medium-size cities whose only or main connections to the Internet come through the major hub cities. Larger cities often have multiple connections to the Internet in and out of the city and would be harder to completely disconnect from the Internet.

The actual impact of a network disruption would depend on a variety of factors, such as the cities affected by the disruption. Grubesic said the most severe impacts would occur if telecommunications equipment were destroyed in the six largest Internet hubs: Los Angeles, New York, Atlanta, Dallas, Chicago, and Washington, DC.

For example, Los Angeles is a major hub location connecting other large cities in the South and West. If Los Angeles were eliminated as a node on the Internet, many other cities in California may not have Internet access. But it would also hurt Internet accessibility in Las Vegas, Phoenix, Tucson, Denver, Dallas and Houston, the study suggests.

A relevant glimpse of what could happen with the loss of a major Internet hub occurred with the Sept. 11, 2001 terrorist attack in New York City, Grubesic said. One major telecommunication hub was located at Ground Zero, and the loss of that hub disconnected three New York counties from the state of New York's computer system. In addition, several major Internet services and e-business providers were left without service for nearly two days.

Grubesic noted that there are more than 40 network provider companies that make up the backbone of the Internet. Many of these companies have agreements to help distribute each other's Internet traffic, which would help if one company's equipment was destroyed in a disaster. Still, most of the companies have hubs in the same cities and a major disaster could destroy the infrastructure of multiple networks.

For that reason, Grubesic said networks should not be concentrated too much in major cities.