Current Research in EEPS: Dr. Christian Huber, Brown University
The role of the state of a shallow subvolcanic reservoir on magma outgassing and explosivity.
Predicting whether a forthcoming eruption will be explosive or effusive is a difficult challenge. The eruptive record of most volcanic systems (I will focus on silicic systems and arcs mostly) hosts both effusive and explosive activity sometimes with little to negligible changes in magma composition. A famous example is Cerro Azul (Quizapu, Chile), a system that erupted twice over about 80 years, the same volume and composition of magma. The first eruption outpoured about 5km3 of dacitic lava, while the second ejected 5km3 of dacite via a dominantly plinian eruption. These “rapid” transition are not uncommon but remain hard to explain. In this presentation I will discuss the role that the subvolcanic magma chamber plays on priming the magma for explosive or effusive eruptions. Eruption triggering and magma ascent are both highly non-linear processes and I will argue, on the basis of the petrological record, that the state of the magma stored in the subvolcanic chamber prior to an eruption (initial conditions) plays a significant role in controlling the subsequent efficiency of outgassing in the volcanic conduit and therefore eruption style.