Volcanic Unrest and Pre-eruptive Processes: A Hazard and Risk Perspective

Volcanic unrest is complex and capable of producing multiple hazards that can be triggered by a number of different subsurface processes. Scientific interpretations of unrest data aim to better understand (i) the processes behind unrest and their associated surface signals, (ii) their future spatio-temporal evolution and (iii) their significance as precursors for future eruptive phenomena. In a societal context, additional preparatory or contingency actions might be needed because relationships between and among individuals and social groups will be perturbed and even changed in the presence of significant uncertainty. Here we analyse some key examples from three international and multidisciplinary projects (VUELCO, CASAVA and STREVA) where issues around the limits of volcanic knowledge impact on volcanic risk governance. We provide an overview of the regional and global context of volcanic unrest and highlight scientific and societal challenges with a geographical emphasis on the Caribbean and Latin America. We investigate why the forecasting of volcanic unrest evolution and the exploitability of unrest signals to forecast future eruptive behaviour and framing of response protocols is challenging, especially during protracted unrest. We explore limitations of current approaches to decision-making and provide suggestions for how future improvements can be made in the framework of holistic volcanic unrest risk governance. We investigate potential benefits arising from improved communication, and framing of warnings around decision-making timescales and hazard levels

Eject! for Matlab

The program "Eject!" calculates the trajectories of ballistic projectiles from volcanic eruptions (Mastin, 2001; 2011). The code was originally written in Visual Basic, which we have now translated into an editable Matlab procedure (Strehlow et al., 2017). Input parameters used here are exemplary for the case of Ruapehu volcano, but can be adapted to any specific case. Additionally, we have written a short script that compares the flight trajectory to the topography of the volcano to determine the flight distance

Probabilistic studies with Eject! for Matlab

The program "Eject!" calculates the trajectories of ballistic projectiles from volcanic eruptions (Mastin, 2001; 2011). The code was originally written in Visual Basic, which we have now translated into an editable Matlab procedure (Strehlow et al., 2017). Input parameters used here are exemplary for the case of Ruapehu volcano, but can be adapted to any specific case. Additionally, we have written a short script that compares the flight trajectory to the topography of the volcano to determine the flight distance

Hydrothermal fluids and where to find them:Using seismic attenuation and anisotropy to map fluids beneath Uturuncu volcano, Bolivia

Mapping fluid accumulation in the crust is pertinent for numerous applications including volcanic hazard assessment, geothermal energy generation, and mineral exploration. Here, we use seismic attenuation tomography to map the distribution of fluids in the crust below Uturuncu volcano, Bolivia. Seismic P wave and S wave attenuation, as well as their ratio (QP/QS), constrain where the crust is partially and fully fluid-saturated. Seismic anisotropy observations further constrain the mechanism by which the fluids accumulate, predominantly along aligned faults and fractures in this case. Furthermore, subsurface pressure-temperature profiles and conductivity data allow us to identify the most likely fluid composition. We identify shallow regions of both dry and H2O/brine-saturated crust, as well as a deeper supercritical H2O/brine column directly beneath Uturuncu. Our observations provide a greater understanding of Uturuncu's transcrustal hydrothermal system, and act as an example of how such methods could be applied to map crustal fluid pathways and hydrothermal/geothermal systems elsewhere