Terrorists do not strike at random, and now a computer programme can calculate the risk of an attack on behalf of the business sector with a particular vested interest in the issue: insurers.
"We don't agree with their ends, but they are not madmen. They have a logic, we can understand it," said Andrew Coburn, director of the terrorism department of Risk Management Solutions (RMS), a risk modelling agency specialising in disasters, after a meeting of major European insurers and reinsurers.
Coburn and his 40-member team at RMS map the logic of terrorist attacks, converting statistical, historical, military, geographical and industrial data and advice from defence experts into trends, graphs and ratios.
The result is a computer programme, now in its fourth edition, that gives subscribers an estimate of the risk of having to provide insurance cover for a terrorist attack in 228 countries.
In the case of the cities most at risk of being targeted, it can give an estimate based on individual streets or buildings. Clients enter into the software the coordinates of the buildings they insure for terrorism.
"We run the analysis and tell them: if you have a bomb of, say, two tonnes in this location, the cost to you would be 10 million dollars," Coburn said.
"We use statistical patterns of risk. We look at the intentions of the terrorists: they tell us a lot about their intentions, we have to listen. They publish, they tell us their reasons" he added. "We know what they are trying to achieve."
The system aims to give insurers data for setting the prices they charge clients and also to alert them if they pass a certain threshold of risk of a terrorist incident in places particularly prone to attacks.
According to RMS, the six top European "hot spots", representing the risk of maximum pay-outs following a terrorist attack, are all in central London. After these, the seventh highest on the list is the second arrondissement, or borough, of central Paris.
Worldwide, Manhattan ranks among the most high-risk places, containing five of the locations most prone to attacks.
RMS estimates there is a 3.5 in 100 chance of a chemical, biological or nuclear attack somewhere in the next 12 months.
The organisation began in 1989 at Stanford University, San Francisco, with the idea of using computer technology to quantify earthquake risks by combining data on the position of fault lines, materials resistance and population density.
This first "risk model" was then adapted to hurricanes, cyclones, floods and other natural disasters.
In the weeks following September 11, 2001, RMS received its first requests from US insurance companies faced with a bill of 32 billion dollars (26 billion euros) following the terrorist attacks. A year later, the first "US Terrorism Risk Model" was ready.
RMS has a cooperation agreement with Jane's, the British defence and information specialists, and holds an annual seminar of terrorism experts from institutions such as the Rand Corporation, Saint Andrews University in Scotland and the Institute of Defence and Strategic Studies in Singapore.
"It's the underwriting process. And portfolio analysis: how much money do I need to have in store to be able to pay for the claims?" Coburn said.
"We don't predict where the attacks will happen, but we suggest the kinds of targets."