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Abstract:
Many factors control the variation on eruptive style, between effusive to explosive, between magmatic to phreatomagmatic. Here two models, one of cone shape and one of cone growth rates, characterize how eruptive style influences how a monogenetic volcano evolves with time.The cone shape model predicts how shifts in eruption style, such as the balance between effusive and explosive behavior or the energetics of explosions, change the shape of the cone, including map view patterns, slopes, and crater sizes. This model controls the delivery of scoria, estimates the downslope movement of scoria, allows for directed blasts, and accounts for the effects of active lava flows on scoria movement.The cone growth rate model predicts how the volumetric supply rate of magma changes during an eruption. Multiple exponential curves are fit to observations of cone growth from historical eruptions. The estimated magma supply rate generally increases with cone volume suggesting that scoria cone volume evolution could be indicative of magma supply rates despite being a variable (and sometimes) small percentage of the magma erupted. While focused on scoria cones, this work hints at how tuff cones, scoria cones, spatter cones, and small shields can be treated as a continuum of monogenetic volcanism from phreatomagmatic-driven explosions to classic bubble-bursting and fire-fountaining to pure lava effusion. The combination of historical observations, population studies and numerical models seeks to emphasize how the observable results are rooted in physical processes. Understanding the physical processes is key to predicting hazards on a systematic, volcanic field level.
