Seasonal rockfall risk analysis in a touristic island: Application to the Tramuntana Range (Mallorca, Spain)

Abstract

Rockfalls are an ever-present possibility in the mountainous context of the Tramuntana Region (Mallorca, Spain). Recent events have shown the high potential for direct and indirect impact on the safety of people and economic activities, lasting for weeks or even months. In the present study, we start from a probabilistic assessment of the rockfall hazard (spatial propensity and temporal recurrence), based on a detailed historical record of occurrences and rockfall modelling, which is subsequently superimposed on three exposure scenarios and on a social vulnerability assessment. Exposure considers the floating population at three seasons of the year, given the area's high tourist aptitude. Vulnerability considers on the one hand the intrinsic characteristics of individuals and, on the other, the characteristics of the surrounding territory that act to facilitate emergency operations, mitigate the immediate impact and enhance rapid recovery. Due to the characteristics of the island and the spatial distribution of tourism, the results show that the highest density of rockfall trajectories potentially affect areas of high exposure, whose access by emergency services is complex. Not being, in general, the areas of highest individual criticality, those areas have in most situations low support capability installed or nearby. The results constitute a useful tool for emergency and risk management planning in multiple sectors linked to risk governance. Despite the high geographic detail of the analysis, these studies do not replace exposure and vulnerability analysis at the building level, for which the contribution of georeferenced Census data is fundamental.