A regional methodology for rockfall hazard assessment in the hazard prevention map of Catalonia 1:25,000. A geomorphological approach

• Published in: Landslides and Engineered Slopes. Experience, Theory and Practice Vol. 1; pp. 1631 - 1636
• Main Authors: Pinyol, J., González, M., Oller, P.
• Format: Book Chapter
• Language: English
• Published: CRC Press 2016
• Edition: 1
• Subjects: Landslide Susceptibility; Reach Analysis; Matric Suction; Geohazard Mapping; Geological Institute; Rockfall Trajectories; Geomorphologic Approach; Potential Volumes; Activity Indicators; Overburden; ICGC; Rock Fall Trajectories; Rocky Slopes; Hazard Degree; Geological Hazard; Regional Methodology; Rockfall Volumes; Slope Stability Analysis; Hazard Matrix; Lithological Layer; Rockfall Hazard; Multi-hazard Map; Catalan Territory; Magnitude Frequency Relationship; Runout Zone
• ISBN: 1138029882; 9781138029880
• DOI: 10.1201/9781315375007-191

One of the functions of the Cartographic and Geological Institute of Catalonia (ICGC) is to “study and assess geological hazards, including avalanches, to propose measures to develop hazard forecast, prevention and mitigation and to give support to other agencies competent in land and urban planning, and in emergency management”. To accomplish these functions, the ICGC began the Geological Hazard Prevention Map of Catalonia (MPRG25M) in 2007. The MPRG25M is designed as a multi-hazard map, indicating the overlapping of different hazard zones in the same area. This article presents the methodology developed for assessing the rockfall hazard. The analysis includes two steps: (a) estimating the magnitude-frequency relationship of the events and (b) estimating the travel distance, based on the angle of reach. The evaluation is done in areas previously identified as susceptible. Susceptibility is defined by the combination of lithology with slope angle. Rockfall frequency and magnitude is obtained by field work with rockfall inventory, activity features, activity evidence and the identification of favorable terrain morphologies. The subsequent processing of these data includes the angle of reach analysis, which determines the area affected by the rock fall trajectories and the degree of hazard. This analysis is systematic and uniform for the whole of the territory to obtain comparable results. The functions of the Cartographic and Geological Institute of Catalonia is to "study and assess geological hazards, including avalanches, to propose measures to develop hazard forecast, prevention and mitigation and to give support to other agencies competent in land and urban planning, and in emergency management". This chapter presents the regional methodology for rockfall hazard assessment in the hazard prevention map of Catalonia developed for assessing the rockfall hazard. The rockfall hazard analysis includes two steps: estimating the magnitude-frequency relationship of the events and estimating the travel distance, based on the angle of reach. The catalogue of phenomena and activity evidence is the base of the further susceptibility and hazard analysis. It consists of a geomorphologic approach and it comprises the following phases: bibliographic and cartographic search, photo interpretation, field survey, and population inquiries. The Geological Hazard Prevention Map of Catalonia is a 1:25,000 scale map where whole of the Catalan territory will zoned according to geological hazard.