Rock physical properties and mechanical implications of a hydrothermal core within Teide volcano, Tenerife

Tenerife (Canary Islands) has undergone several lateral collapses, each followed by the regrowth of its edifice. In this context, the active stratovolcano Teide, in central Tenerife, has been regrowing following a north-directed collapse. Previous studies suggest that Teide continues to exhibit signs of potential flank instability to the north related to ongoing volcano spreading. This flank instability is thought to accelerate during magmatic and hydrothermal episodes. While outward displacement commensurate with spreading is not observed, morphological and structural features have still been linked to possible spreading. The volcano shows a concave slope profile on the northern flank, as well as normal faulting at the summit. These features may imply (1) a gently dipping low-strength breccia layer at the base of the volcano, facilitating large-scale spreading; and (2) the presence of a hydrothermally altered core and crater area later overgrown by the edifice. Here, we characterise the physical and mechanical properties of rock samples collected from (1) the pre-medieval Teide cone (Old Teide), (2) Old Teide’s crater rim, (3) Teide’s new summit cone, and (4) lava flows from Teide’s most recent summit eruption (Lavas Negras) using laboratory measurements of density, porosity, permeability, thermal conductivity, P-wave velocity, Young’s modulus, and uniaxial compressive strength. Combined with high-resolution drone imagery, these measurements provide critical data for computational models of large-scale volcano stability. This multidisciplinary study aims to test whether mechanical weakening from a hydrothermally altered core alone can cause the observed slope concavity, which would have significant implications for hazard assessment and monitoring of volcanic collapse events.