From Magma to Tephra: Modelling Physical Processes of Explosive Volcanic Eruptions(v. 4 Developments in Volcanology)

Hot magma rising through the Earth's crust releases gases that expand and may come into contact with external water that vaporizes. The magma is then fragmented into an accelerating gas-particle/droplet mixture that is shot into the atmosphere, possibly in an overpressured state, where it may buoyantly rise up into the stratosphere as an ash plume, partially through totally collapse back to the surface, or rapidly expand sideways,or perform a combination to these processes. Tephra is then deposited on the Earth's surface by pyroclastic fall, flow or surge, or some hybrid mechanism. The combination of processes that operate from the degassing of magma to the emplacement of tephra makes an explosive volcanic eruption, and the physical characterization of these processes is the scope of this book. This text reviews basic physics and summarizes recent physical modelling advances of processes operating during explosive volcanic eruptions. The book addresses topics such as: magma degassing; magmatic and phreatomagmatic fragmentation; flow in the conduit; eruption column dynamics; transport and emplacement processes of pyroclastic fall, flow and surge.

Table of Contents:
Magma degassing and fragmentation- recent experimental advances, D.B. Dingwall - abstract, introduction, nucleation, bubble growth, accelerating tow-phase flows, brittle failure, post-fragmentation effects, non-explosive degassing, relaxation geospeedometry of volcanic glass, bibliography; phreatomagmatic explosions, B. Zimanowski - introduction, explosive phreatomagmatic volcanism, physics of volcanic MFCI, diagnosis and monitoring of phreatomagmatic explosions (volcanic MFCI); volcanic conduit dynamics, P. Papale -introduction, review of magma ascent models, magma ascent dynamics in steady state explosive eruptions; eruption column physics, G.A. Valentine - introduction, multiphase flow and the multifield approach, multifield governing equations, closure of governing equations, approaches to analysis of eruption column dynamics; steady state dynamics, time-dependent dynamics with constant eruption rate, time-dependent dynamics with transient eruption rate, influence of the ambient medium, conclusion; plinian eruption columns - particle transport and fallout, M. Rost - introduction, models of particle transport in plinian columns, clast dispersal in crosswinds, assessment of eruption parameters; pyroclastic flow transport mechanisms, A. Freundt, M.E. Bursik - introduction, characteristics of ignimbrites and pyroclastic flows, transport processes of sedimenting particulate flows, pyroclastic flow models, from model flows to ignimbrites - complexities during emplacement, concluding remarks; pyroclastic surges and compressible two-phase flow, K.H. Wobletz -introduction, observations, theory, conclusion - surge are hazardous but economically significant. Appendices: origin of the SFT equations; analysis of surge steam condensation. References. Subject index.