Spatio-Temporal Modeling of Human Vulnerability in the Case of a Tsunami in Padang,Indonesia

Padang is known to be one of the most exposed cities in Indonesia to the threat of tsunamis. Some available models show that the urban area in the coastal zone would be inundated by a potential tsunami. Considering this threat, our objective is to estimate which areas of the city are the most endangered in order to plan an evacuation that is adapted to the daily influx of population at this local scale. To address this challenge, we propose a methodology based on a ground survey in Padang at a very fine scale. This survey is based on the hypothesis that inhabitants tend to have a common rhythm of life, which results in varying population distribution in time, according to the period and its activities. Furthermore, results of this survey are coupled with a submersion model, which provides an estimation of flood height and speed for every location, in order to propose a synthetic indicator of vulnerability, the human risk index, which combines both structural and human vulnerability. The variations in population density and potential casualties are then discussed through spatio-temporal maps that are used for designing evacuation scenarios. In particular, a measure of evacuation capability to existing vertical and topographic refuges is achieved for each of those scenarios, thus providing direction for authorities planning risk mitigation.