An evaluation method for the urban post-earthquake fire risk considering multiple scenarios of fire spread and evacuation

An evaluation method for urban post-earthquake fire risk is presented. Urban fires and urban evacuations are highly dependent on uncertain factors, such as the number and locations of fire outbreaks, the wind velocity and direction, and the population distribution. To implement effective measures to ensure the safety of buildings and individuals in fires, a method to evaluate the effectiveness of the various safety measures that consider the influence of the uncertain factors is essential. Risk is introduced into the proposed method, in which the risk is defined as the probability that the ratio of burned-down buildings or fire fatalities in a district will exceed a threshold within a given time period after an earthquake. The risk is calculated by a combination of Monte Carlo simulation and physics-based fire-spread/evacuation simulation, in which uncertainty is considered in the following inputs: (1) the number and locations of fire outbreaks; (2) the firefighting at the initial stages; (3) the weather; (4) the earthquake-related structural damage to buildings; (5) the initial evacuee locations and (6) the obstruction of roads. In this paper, the risk of Kyoto City was evaluated for eight types of inland earthquake to demonstrate the use of the model. As a result, the effectiveness of countermeasures that improve the fire resistance of buildings could be quantified in terms of risk reduction. This result indicates that the method could be an effective tool for disaster prevention.