The role of porosity on the engineering geological properties of 1669 lavas from Mount Etna.

A comprehensive laboratory characterization of volcanic rocks belonging to the 1669 lava flow of Mount Etna, recognized as one of the largest and most catastrophic event ever occurred, is presented herein with the aim of investigating on their peculiar mechanical attitude. The multi-disciplinary approach proposed herein pointed out that although originated by the same eruptive event, 1669 trachybasaltic lavas are characterized by relevant differences in porosity and rock fabric, from both the qualitative and quantitative points of view. This is an interesting aspect, because such rocks are quarried for the production of high quality material to be employed for engineering geological purposes even in the "Val di Noto" UNESCO World Heritage site. In this perspective, their detailed characterization is an essential practice, even preparatory for the engineering geological use. To this purpose, this paper provides a focus on the laboratory investigation of these rocks, which according to three different porosity classes, underwent petrographic, physical, mechanical and seismic analyses. Interesting statistical correlations allowed understanding the mutual dependence of the main engineering geological parameters, highlighting how porosity, through both vesicles and microcracks, plays a leading role from the engineering geological point of view. Achieved results provide a scientific casuistry on this topic and are a reliable reference for studies on similar rock types worldwide, since lavas are among the most used rock materials in the engineering geological practice. [ABSTRACT FROM AUTHOR]