Revision and improvement of the PTVA-3 model for assessing tsunami building vulnerability using "international expert judgment": introducing the PTVA-4 model

This work reviewed, assessed, enhanced and field-tested one of the most widely used index-based methods for assessing the vulnerability of buildings to tsunamis: the Papathoma Tsunami Vulnerability Assessment (PTVA) model. The review and assessment were undertaken through a participatory survey process engaging authors of scientific literature during 2005-2015 in the field of building vulnerability to tsunamis. Expert respondents updated the weights of the PTVA building vulnerability attributes based on their expertise and insights from the 2011 Tohoku Tsunami. The respondents were also free to suggest additional PTVA building attributes and to provide open comments on the model. We then analysed the outcomes of the questionnaire and we used them to generate a new improved version of the model, the PTVA-4, which we field-tested in the area of Botany Bay (Sydney), New South Wales. Using a cohort of over 2000 buildings and a tsunami scenario numerically simulated using state-of-the-art hydrodynamic modelling techniques, we applied the PTVA-4 model and compared the outcomes against its predecessor (i.e. the PTVA-3). Results showed the PTVA-4 model is significantly more accurate and more sensitive to variations in the tsunami demand parameter, the attributes of the exposed buildings and their surroundings. The PTVA-4 model is the first tool of its kind to integrate the judgment of specialised scientists worldwide. It constitutes a viable option to assess the vulnerability of buildings in areas where no tsunami vulnerability curves have been developed yet, or to consider the contribution to vulnerability given by a significantly wider range of building engineering and physical attributes. An ArcGIS toolbox that automatically calculates the relative vulnerability of buildings using the new PTVA-4 model is attached to this paper.