Using a dataset that we construct on terrorist activity involving the use of chemical, biological or radionuclear (CBRN) agents, we calculate the likelihood of a catastrophic event of this nature. Assuming a continuation of recent trends in the use of CBRN agents, an attack of the same magnitude as that on the Tokyo subway in 1995 is expected to occur by 2009. Consistent with pronounced non-stationary patterns in these data, the "reoccurrence period" for such an attack is decreasing every year. Similarly disturbing trends are evident in a broader dataset which is non-specific as to the methods or means of attack. Thus for instance an attack that leads to the deaths of 1000 people is expected to occur within the next ten years. However an attack of the same magnitude as the September 11 tragedy, when nearly 3000 people died, is not expected any time soon.
Mohtadi, Hamid, and Antu Panini Murshid. 2007. “Analyzing Catastrophic Terrorist Events with Applications to the Food Industry.” In The Economic Costs and Consequences of Terrorism, ed. Harry Richardson. London, UK: Edward Elgar. https://www.researchgate.net/publication/239569165_Analyzing_Catastrophic_Terrorist_Events_with_Applications_to_the_Food_Industry