A brief review of the effect of wildfires on rockfall occurrence

Wildfires and rockfalls are among the major hazards in forested mountainous regions across Europe. Understanding processes and conditions that lead to rockfalls during and after a wildfire in different geological contexts is, therefore, of great relevance. The increase of rockfalls associated with the occurrence of wildfires is connected to several factors, not only in the detached area but also in the propagation and affected area. Wildfires cause changes in the mechanical properties of rocks and discontinuities as well as the loss of protective capacity from vegetation, complemented by the effect induced by firefighting activities and by extreme temperatures that may deteriorate the installed protective measures. After the occurrence of a wildfire, there is an increase in the frequency and intensity of rockfalls in the burned area, causing a major impact of rockfalls on road networks and inhabited areas. Additionally, the rockfall risk perception is usually increased due to the removal of vegetation by wildfires, exposing both rock blocks and the rock mass. In this review, the main factors that influence the occurrence of rockfalls after a wildfire are briefly reviewed.