3D Seismic tomography of El Hierro: insights into the pluming system of a monogenetic volcanic field

Abstract

Understanding how monogenetic volcanic systems work requires to understand the local and regional stresses (i.e structural controls) that govern magma migration inside them and why they seems to change from one eruption to another. The 2011-2012 El Hierro eruption (Canary Islands) showed how the characteristics of unrest, including a continuous change in the location of seismicity, made unpredictable the location of the future vent, thus making hard to conduct short term hazard assessment. A 3D seismic tomography constructed using the seismicity occurred during the pre-eruptive unrest and latter post- eruptive seismic crisis not related to further eruptions, reveal the structural complexity of the interior of El Hierro. It shows a number of stress barriers corresponding to tectonic structures and blocked pathways from previous eruptions, which controlled ascent and lateral migration of magma and, together with the existence of N-S regional compression, reduced its options to find a suitable path to reach the surface and erupt.