Abstract

ABSTRACT The island of Gran Canaria (Canary Islands, Spain) is characterized by a large variability of volcanic rocks reflecting its volcanic evolution. The geological map provided by Geological Survey of Spain at 1:25.000 scale shows more than 109 different lithologies and it is too complex for environmental and engineering purposes. This work presents a simplified geotechnical map with a small number of classes grouping up units with similar geotechnical behaviours. The lithologies were grouped using about 350 rock samples, collected in the seven major islands of the Archipelago. The geotechnical map was used to model rockfall hazard in the entire island of Gran Canaria, where rockfalls are an important threat. The rockfall map was validated with 128 rockfall events along the GC-200 road, located in the NW sector of Gran Canaria. About 96% of the events occurred along sections of the road where the number of expected trajectories is high or moderate.

Highlights

  • The island of Gran Canaria (Canary Islands, Spain) is a steep volcanic relief characterized by numerous deep radial ravines and a very abrupt coastline with high cliffs (Menéndez et al, 2008 and see Main Map)

  • A simplified geotechnical map with a smaller number of classes showing lithologies with similar geotechnical behaviours represents a more appropriate tool for many applications, including those aimed at managing natural risks

  • We present a new, simplified geotechnical map for the island of Gran Canaria based on the geotechnical characterization of CONTACT Roberto Sarro r.sarro@igme.es Department of Natural Hazards, Geological Survey of Spain, Ríos Rosas 23, Madrid 28003, Spain

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Summary

Introduction

The island of Gran Canaria (Canary Islands, Spain) is a steep volcanic relief characterized by numerous deep radial ravines and a very abrupt coastline with high cliffs (Menéndez et al, 2008 and see Main Map). Several geological maps of Gran Canaria are available at different scales. The map is rather complex to use for some purposes, such as environmental studies and engineering modelling. For this reason, a simplified geotechnical map with a smaller number of classes showing lithologies with similar geotechnical behaviours represents a more appropriate tool for many applications, including those aimed at managing natural risks. A first attempt of geotechnical map for Gran Canaria was elaborated by the regional government (territorial information system of the Canary Islands, available at https://visor.grafcan.es/visorweb/), with a special focus on ground characteristics for building construction. The new geotechnical map was used to model and evaluate rockfall hazard at regional scale for the entire island

Geographical and geological setting
The rockfall map
Validation
Findings
Discussion and conclusions

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