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 aimof investigating on their peculiar mechanical attitude.The multi-disciplinary approach proposed herein pointed out that although originated by the same eruptiveevent, 1669 trachybasaltic lavas are characterized by relevant differences in porosity and rock fabric, from boththe qualitative and quantitative points of view. This is an interesting aspect, because such rocks are quarriedfor the production of high quality material to be employed for engineering geological purposes even in the“Val di Noto” UNESCOWorld 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 tothree different porosity classes, underwent petrographic, physical, mechanical and seismic analyses. Interestingstatistical correlations allowed understanding themutual dependence of themain engineering geological parameters,highlighting howporosity, through both vesicles and microcracks, plays a leading role fromthe engineeringgeological point of view. Achieved results provide a scientific casuistry on this topic and are a reliable referencefor studies on similar rock types worldwide, since lavas are among themost used rockmaterials in the engineering geological practice.