Evaluation method of restoration process for road networks after volcanic eruption

Japan is located in the circum-Pacific orogenic zone, and is one of the world´s most volcanic countries. This paper is focused on the damage caused by the ashfall resulting from volcanic eruptions. In particular, the damage to the traffic network is investigated. First, we address the impact of ashfall on the traffic network and present “functional fragility curves” for road traffic capacity, which represent the conditional probabilities of traffic disruptions caused by ashfall. Then, we present a method for restoring the traffic network in which estimations calculated using functional fragility curves are applied. We use an optimum road maintenance model to resolve the problem of ash removal. As a case study, we use the area of the city of Miyakonojo, since this city is located near the Kirishima volcano. The results are compared with the real damage caused by the volcanic eruption in 2011.