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Forensic analysis of explosions: Inverse calculation of the charge mass

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Author: Voort, M.M. van der · Wees, R.M.M. van · Brouwer, S.D. · Jagt-Deutekom, M.J. van der · Verreault, J.
Type:article
Date:2015
Publisher: Elsevier Ireland Ltd
Source:Forensic Science International, 252, 11-21
Identifier: 522762
doi: doi:10.1016/j.forsciint.2015.04.014
Keywords: Explosives · Explosion · Forensic analysis · Blast · Debris · Damage · Statistical analysis · Blast · Damage · Debris · Explosion · Forensic analysis · Statistical analysis · Accuracy · Building · Computational fluid dynamics · Environmental exposure · Explosion · Explosion risk · Forensic identification · Mass disaster · Prediction · Process development · Reliability · Risk assessment · Statistical model · Urban area · Validation process · Mechanics, Materials and Structures · EBP - Explosions, Ballistics & Protection WS - Weapon Systems · TS - Technical Sciences

Abstract

Forensic analysis of explosions consists of determining the point of origin, the explosive substance involved, and the charge mass. Within the EU fP7 project Hyperion, TNO developed the Inverse Explosion Analysis (TNO-IEA) tool to estïmate the charge mass and point of origin based on observed damage around an explosion. In this paper inverse models are presented based on the two most frequently occurring and reliable sources of information: window breakage and building damage. The modets have been verified by applying them to the Enschede firework disaster and the Khobar tower attack. Furthermore a statistical method has been developed to combine the various types of data, in order to determine an overall charge mass distribution. In relatively open environments, like for the Enschede firework disaster, the models generate realistic charge masses that are consistent with values found in forensic literature. The confidence interval predicted by the IEA tool is however larger than presented in the literature for these specific cases. This is realistic due to the large inherent uncertainties in a generic tool. Furthermore, to our judgment often a too narrow range of charge masses is reported compared to the evidence. The IEA-models give a reasonable first order estimate of the charge mass in a densely built urban environment, such as for the Khobar tower affack. Due to blast shielding effects which are not taken into account in the IEA tool, this is usually an under prediction. To obtain more accurate predictions, the application of Computational Fluid Dynamics (CFD) simulations is advised. The TNO IEA tool gives unique possibilities to inversely calcutate the TNT equivalent charge mass based on a large variety of explosion effects and observations. The IEA tool enables forensic analysts, also those who are not experts on explosion effects, to perform an analysis with a largely reduced effort.