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 Socorridos pumping station and water storage tunnel are located at Madeira Island, Portugal, and are part of a system conceived to reutilize the water flow from the Socorridos hydroelectric plant. This facility includes an underground cavern with 26 m high, 12 m wide and 44 m length, and a tunnel 1250 m long with a storage capacity of 40,000 m 3 . The rock mass at the site is of volcanic origin with most of the excavation performed in a mass of volcanic breccia and basalts but with consolidated alluvia recent deposits located in the roof arch of the cavern. A description of the main characteristics of the project is presented and the results predicted by the design are compared with the values given by the instrumentation.