ABSTRACT: The rehabilitation of the volcanic natural cave that constitute "Los Jameos del Agua" Auditorium, was a challenge in the development of new technologies, materials and even machinery, specifically designed for strengthening and conditioning this impressive natural area. As a consequence that this is the biggest natural Auditorium in Europe, and a specially protected space, both, the project and its execution have required to contemplate the double condition of securing more than 800,000 people who use it every year, while maintaining the original aesthetics.

ABSTRACT: The main feature of aquifers in volcanic islands with high rainfall rates and steep topography is that they are on raised, mainly due to the presence of volcanic dikes. Dikes are igneous bodies with very high aspect ratio, which means that their thickness is usually much smaller than the other two dimensions and tend to be vertical or of high dip angle. It can be considered as impermeable and interconnected walls where aquifers, which are recharged by rain, raise the water table between the dikes. This is especially important in volcanic rift zones. The method to obtain water in these volcanic areas involves digging horizontal galleries with explosives. The galleries cross the dikes and drain the water from the water saturated area. The main problem of this type of perforation is to obtain the water continually, without the possibility of water regulation. This question has been solved by means of the reconstruction of several technically viable dikes, to enable the store of water resources through channels in order to regulate the water wealth of the built galleries. Methods, results and viability on the use of the volcanic materials as relevant works of civil engineering highlights on the following paper.

ABSTRACT: The town of Santa Cruz de Tenerife, NE Tenerife, Canary Islands, Spain, spreads on Young volcanic materials which show a great heterogeneity. Very often this means a hard problem to overcome for building projects. This paper describes the geotechnical features of volcanic formations of Santa Cruz de Tenerife on data from building geotechnical studies, geotechnical maps, and rock geotechnical properties database of the Regional Ministry of Works of the Government of the Canary Islands. An inventory of different types of building foundations has been made in order to establish a correlation between volcanic terrains and foundation solutions. As a conclusion, a geotechnical zoning map of Santa Cruz de Tenerife is proposed as preliminary foundation solutions in building projects.