Catastrophe modelling firm AIR Worldwide has updated its terrorism model for the United States to more comprehensively model the extent of damage from conventional bomb blast attacks.

Using the model, re/insurers can estimate the potential property, business interruption, workers’ compensation, and personal injury losses that can arise from acts of terrorism in the US. The deterministic event modelling capabilities in Touchstone allow users to select a blast size and location to analyse the impact it will have on their specific book of business.

“When terrorists use conventional weapons, the effects of which tend to be highly localised, they are likely to be targeting specific buildings or facilities,” said Tao Lai, vice-president, research, AIR Worldwide. “The amount of damage that occurs at or near the site of an attack depends on a wide variety of factors. In addition to the type of weapon used, the surrounding buildings, building dimensions and blast intensity propagation can have a profound effect on the damage from an attack.”

A distinctive feature of the AIR US Terrorism Model's blast intensity and damage calculation methodology is the explicit consideration of blast intensity propagation in different built environments within a building.

To create the new model, AIR used 3D Computational Fluid Dynamics simulations to ensure more accurate blast intensity propagation reflecting the configuration and proximity of buildings in a variety of urban environments. Vulnerability accounts for both overpressure and pressure impulse outside and inside a building, which inform the estimation of building damage, contents damage and personal injury. Because damage is calculated through the aggregation of cells and blast intensity is modified both as it enters the structure and as it travels through the interior, model users can obtain detailed loss results for a specific floor of interest.

“The threat of terrorism continues to rise and managing risk from terrorism has become an essential part of business,” Lai added. Updates to the AIR Terrorism Model for the United States include enhancements to the modelling of conventional bomb blast attacks. In particular, the updated model can produce a more realistic damage extent for various forms of blast attacks, including the Oklahoma City bombing which was estimated to have had the energy of approximately 4,000 lbs. of TNT and damaged 324 structures within a five-block radius.”

The updated model also reflects learnings from the detonation of a recreational vehicle bomb in downtown Nashville, TN in December 2020, a reminder that this form of blast attack remains a real threat.

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