The concept of a disruption index: application to the overall impact of the July 9, 1998 Faial earthquake (Azores islands)

The earthquake that struck Faial, Pico and São Jorge in 1998 has allowed the collection of an unprecedented quantity of good-quality data on damage to construction, costs of repair and other variables. A general overview of the impact of the earthquake is presented, and its effects on the population, housing, monumental structures and economy 10 years after its occurrence are analysed and briefly reported in this paper. We present the overall results obtained from multiple sources of information, primarily from an integrated database containing all the data gathered. The results that describe the inflicted damage, costs of repair and other variables are presented both statistically and geographically. This information was valuable for the construction of an overall earthquake impact based on the systemic analysis of the urban area through the identification of criteria and definition of descriptors leading to a disruption index. The paper is developed as follows. First, we introduce the descriptions of the earthquake effects on the broader set of existing urban systems. In the second part we present the main methodological aspects leading to the disruption index, as well as analysing and discussing the data to provide a clearer picture of how the analysed systems and their disruption affect an urban area.