Water-rock interactions, magma composition and volatile inputs are also highly variable compared to the more uniform basaltic crust of deep-sea systems [38].
Conversely, the low S/Cl and Na/Cl ratios in the RSSM region may be due to the variable reactivity of ash to SO2 within the high-temperature eruption plume, and subsequent scavenging of HCl by ice- or water-coated ash, manifested in terrestrial deposits via both changes in magma composition and the influence of tephra dispersal and sedimentation patterns.
We found similar nonlinear degassing behaviour over a range of magma compositions and volatile contents.
(a) Theoretical degassing curves were calculated for rhyolitic magma compositions and show the pressure dependence of the moles of H2O and CO2 released during open-system degassing by one kilogram of magma for each 1-MPa pressure decrease.
Results were compared between these two well-characterized eruptions of different explosivities and magma compositions and indicate that bubble size distributions (BSDs) are bimodal, suggesting a minimum of two nucleation events during both eruptions.
Initially FLOWGO was run using the chemical model validated for the 2010 eruption, and the magma composition, crystal and vesicle properties of the same eruption.
Because all the investigated ignimbrites, magmatic and phreatomagmatic, share similar magma composition, volume and mobility, we attribute the temperature difference to magma water interaction, highlighting its pronounced impact on thermal dissipation, even in large-volume eruptions.
"Research has been done on magma composition, physical volcanology, and ash cloud modeling but it hasn't been really summarized and put into one whole picture," Ilyinskaya says.
These two particular events represent two different eruptive styles (sub-Plinian and Plinian, respectively) and two different magma compositions (basalt and dacite, respectively).
Source depth depends on a range of factors relating to buoyancy, magma composition, stress conditions and pre-existing structural features (e.g., Chaussard & Amelung, 2014), as well as conditions that promote the amalgamation of lenses of melt and volatiles in a mush system to form larger bodies of eruptible magma (e.g., Cashman et al., 2017).
Papers may report anything from one to up to six pertinent parameters, namely VEI, bulk tephra volume, DRE, magnitude, tephra density and magma composition (from which magma density can be calculated).
