Energetic ash-producing volcanic eruptions are driven by the diffusive and decompressive growth of bubbles (mostly water) during ascent in a magma conduit. The spatial distribution of bubble nucleation sites is one of the primary controls on ash-forming fragmentation. However, the initial formation of bubbles in a supersaturated magma is problematical, especially for homogeneous nucleation. Excessive surface tension pressure should preclude the existence of small bubbles, because exsolved water is driven back into the melt. This is the “tiny bubble paradox.” We suggest that—under special circumstances—the tiny bubble paradox may be circumvented by spinodal decomposition, a process in which uphill diffusion enables spontaneous unmixing of phases to reduce the free energy of the system. As spinodal decomposition progresses, three dimensional, quasi-spherical, zones of water-rich magma develop. These zones are characterized by an increasingly high concentration of dissolved water at the centers and reducing concentration at the margins. Bubbles are born when the concentration of water in the interior of the water-rich zones goes to 100% and the concentration of melt goes to zero. The small, nascent, bubbles that emerge will be buffered from melt by water-rich shells with increasing melt concentration away from newly formed bubbles. This diffuse concentration gradient of water means that there is no surface, per se, for surface tension to arise. This is the crux of the solution of the tiny bubble paradox. Particle morphology may be used to distinguish ash with spinodal origins from ash associated with typical (metastable) bubble nucleation. Spinodal decomposition occurs at a wavelength determined by the pressure, temperature, and viscosity of the magmatic system. This wavelength should create bubbles of uniform size and bubble walls of equal strength in a fragmenting magmatic foam, leading to sharply mono-modal vesicle and ash particle size distributions. Classical bubble nucleation should create more-variable bubble sizes and bubble wall strengths, leading to a broader particle size distribution. Better understanding the mechanism of bubble formation in magmatic systems will, in turn, enable better understanding of hazardous, explosive, eruptions.

Ash-producing volcanic eruptions are a major natural hazard and the magnitude of the explosivity of these eruptions have been indicated for decades by a semi-quantitative “Volcanic Explosivity Index (VEI)” based on a number of interdependent factors, (eruption duration, volume of ejected material, eruptive column height, tropospheric and stratospheric injection, and qualitative descriptors). We present a simple empirical formulation for a fully quantitative VEI (𝑉𝐸𝐼Hc), based solely on eruption column height. This method directly translates the height of the eruption column into VEI, a useful formulation for immediate understanding of the explosivity of eruptions as they are taking place. This new scale is calibrated for convenience and familiarity to span the same range of values as the existing, semi-quantitative, VEI scale. In addition to being a simple and quantitative approach, this new method, translating column height directly into VEI, has the advantage of being calculated in real time during an eruption. This will improve immediate response by aviation, hazard management, and others to mitigate societal impact of hazardous eruptions.

The increasing role of women in leadership roles may be both a cause and effect of public attitudes. Recent politicization of science amidst increasing polarization of American politics juxtaposed with examples of female leadership (Fleadership) throughout the U.S (and abroad) begs the question of how gender impacts crisis response decision-making. Here, we investigate at the state level, female gubernatorial leadership, recent presidential (and VP) voting patterns, climate denial, and COVID/100k. These reveal correlations between climate denial, high COVID/100k, and presidential votes for exclusively male candidates. Americans who embraced federal Fleadership in 2016 and again in 2020 were less likely to deny climate change and spread COVID-19. The results suggest that rather than Fleadership inspiring responsible COVID preventative behavior at state or national levels, or leading to better understanding of climate change, the populations who tend to elect females, also understand science more than those who do not.

Explosive, ash-producing volcanic eruptions are a significant natural hazard with the potential for loss of life, economy, and infrastructure. Turrialba is an active stratovolcano located in the Central Cordillera of Costa Rica. The edifice is located only 35 km east-northeast of Costa Rica's capital city and poses a threat to its central valley, the social and economic hub where more than half of the population resides. The most recent eruption took place in 2016-2017, consisting of four eruption phases. Preliminary observations using SEM show significant morphological differences between the various eruption phases, including the amount of dust and crystals that are present. The morphology of volcanic ash is fundamental to our understanding of magma fragmentation, and in transport modeling of volcanic plumes and clouds. The chemistry of the ash particles produced by fragmenting magmatic foams may affect their evolving morphology throughout the various stages of eruption. In addition, eruption energetics may play a role in ash morphology. Separating the roles of chemical heterogeneity and evolving energetics requires careful examination of ash morphology and its relation to composition. In this way, we take some initial steps in closing the knowledge gap between eruption mechanisms and how and why these mechanisms are exhibited in the morphology of ash during explosive eruptions.