Abstract
Volcanic eruptions are unsteady multiphase phenomena, which encompass many inter-related processes across the whole range of scales from molecular and microscopic to macroscopic, synoptic and global. We provide an overview of recent advances in numerical modelling of volcanic effects, from conduit and eruption column processes to those on the Earth s climate. Conduit flow models examine ascent dynamics and multiphase processes like fragmentation, chemical reactions and mass transfer below the Earth surface. Other models simulate atmospheric dispersal of the erupted gas-particle mixture, focusing on rapid processes occurring in the jet, the lower convective regions, and pyroclastic density currents. The ascending eruption column and intrusive gravity current generated by it, as well as sedimentation and ash dispersal from those flows in the immediate environment of the volcano are examined with modular and generic models. These apply simplifications to the equations describing the system depending on the specific focus of scrutiny. The atmospheric dispersion of volcanic clouds is simulated by ash tracking models. These are inadequate for the first hours of spreading in many cases but focus on long-range prediction of ash location to prevent hazardous aircraft - ash encounters. The climate impact is investigated with global models. All processes and effects of explosive eruptions cannot be simulated by a single model, due to the complexity and hugely contrasting spatial and temporal scales involved. There is now the opportunity to establish a closer integration between different models and to develop the first comprehensive description of explosive eruptions and of their effects on the ground, in the atmosphere, and on the global climate.
Highlights
Introduction and review of basic conceptsExplosive eruptions are among the most fascinating and complex natural phenomena
Ash is hazardous as it falls on the ground where it accounts for 5% of direct casualties and for much of the widespread damage from explosive eruptions
The main objective of simulations on the global scale is to understand the impact of large volcanic eruptions, which reached the stratosphere on atmospheric dynamics and chemistry
Summary
Explosive eruptions are among the most fascinating and complex natural phenomena. At their initiation stage, gas-rich viscous magma experiences a pressure drop (a little as in the uncorking of a champagne bottle but where the liquid would be 104 to 1012 times more viscous, and over-pressure is tens of bars). Decompression to atmospheric pressure, vigorous entrainment, rapid heat exchange from pyroclasts (about 90% and 60% of them are typically less than 1 mm and 60 μm in size respectively) to the entrained air (on timescale of 1-100 s) and further expansion and lowering of bulk density happen This can generate a buoyant eruption column rising up to 10-50 km, from which ash falls out. Gases condense and freeze on ash, hydrometeors and the aggregates (Tabazadeh and Turco, 1993; Textor et al, 2003b,c) These processes affect residence times, removal rates and the stratospheric injection of gases (i.e., the initial volcanic forcing upon climate). Multi-scale numerical modelling, and experimentation, together with remote sensing and in situ measurements will play a key role in advancing understanding of these processes
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
