Predicting terrorismResearchers try to develop a methodology for predicting terrorist acts

While counterterrorism agencies rely on surveillance and other forms of classified data to predict terrorist attacks, researchers and analysts are attempting to define what terrorism is and how it has evolved over time in order better to identify trends and patterns in terrorist activities. This better understanding may help predict the next major attack.

Erin Miller of the National Consortium for the Study of Terrorism and Responses to Terrorism (START) at the ) University of Maryland — START produces and maintains the Global Terrorism Database (GTD) — leads an effort to record terrorist events and make the data available to researchers. Miller has defined terrorism as “the threatened or actual use of illegal force and violence by a non-state actor to attain a political, economic, religious, or social goal through fear, coercion, or intimidation.”

According to Scientific American, analyses based on GTD overwhelmingly show that the number of reported terror events — from targeted assassinations to hijackings and suicide bombings — has sharply increased worldwide since 2000, mostly driven by events in the Middle East, Africa, and south Asia. Half of all global terrorist attacks in the past decade, and 60 percent of fatalities, occurred in Iraq, Afghanistan, and Pakistan.

Post-9/11, Europe and North America suffered relatively few terrorist attacks partly due to the counterterrorism measures carried out by their intelligence agencies. In contrast, areas controlled by terrorist groups, including Afghan Taliban, Islamic State (ISIS), or Boko Haram, have little or no form of counterterrorism operations present.

Successful terrorist plots in the West, such as the 2004 attacks in Madrid, 2005 bombings in London, and recently the Paris attacks, likely escaped law enforcement’s radar due to a shift in strategy by major terrorist networks. Al-Qaeda and ISIS have begun to use fewer operatives, relying instead on small and independent cells to carry out attacks. This strategy has made predicting recent terrorist events that have occurred in the West difficult for researchers.

Still, some believe the information available on GTD can help in making solid predictions. According to a 2013 report by Aaron Clauset, a computer scientist at the University of Colorado Boulder, the likelihood and magnitude of terrorist attacks are related under a power law which assumes that a series of small events, such as the attacks in Paris, will sooner or later be followed by a large rare event. Clauset predicts that, given the rate of small-scale attacks, there is a 30 percent chance of another 9/11-scale attack in the next decade somewhere in the world.

Caluset’s predictions are helpful not just for counterterrorism experts, but also for insurance underwriters who must consider the terrorism risk faced by large projects. The 9/11 attacks resulted in insured losses exceeding $40 billion. A similar or larger attack in another major U.S. city would cause financial losses in excess of $100 billion, according to Risk Management Solutions, which develops terrorism risk models for insurers.

Most estimates, however, tend to be weak due to missing variables which are available only to some law enforcement agencies. “You cannot reliably track terrorism risk without access to classified information,” says Erwann Michel-Kerjan, executive director of the Wharton Risk Center at the University of Pennsylvania in Philadelphia.