The possibility of using volcanic caverns associated with lava tubes is analysed according to their geological and geomorphological configuration and their dimensions. Each particular risk is defined and studied by considering its threat. The different natural risks are grouped into four categories:
Group I: Structural instability zones due to hanged strata or extremely low width levels at the top of the cave.
Group II: Medium and large block instabilities.
Group III: Small block instabilities.
Group IV: Surface weathering and instabilities in rock particles (sand or gravel).
In this chapter this methodology is applied to the well-known auditorium of " Los Jameos del Agua", located in Lanzarote. This volcanic island forms part of the Canary archipelago. This volcanic tube is visited by more than 800,000 people per year.
After an analysis of the different alternatives, the proposed technical solutions for each level of risk are described and the results of some calculations are shown.