B018822 - VULCANOLOGY

Italian

Physical description of the volcanic process. Definition of the main physical, rheological and compositional parameters (and of their syn-eruptive variability) driving magma ascent and dispersal to the surface. Eruptive dynamics and processes of magma transport and deposition. Description of the different styles of volcanic activity, with special regards to explosive volcanism.

- Cas, R.A.F. e Wright J.V. 1987. Volcanic successions. Modern and Ancient London. Allen and Unwin.
- Fisher R.V. e Schmincke H.U. 1984. " Pyroclastic rocks". Berlin: Springer, Verlag.
- Scandone R, Giacomelli L 1998. Vulcanologia. Principi fisici e metodi d’indagine. Napoli, Liguori Editore.
- Sigurdsson H. ed. 2000 Encyclopedia of Volcanoes. Academic Press
- Lockwood JP, Hazlett RW -Volcanoes: Global Perspectives - Wiley-Blackwell
- Parfitt E.A., Wilson L. – Fundamentals of Physical Volcanology – Blackwell Publishing

To introduce the student to the physical concepts which govern volcanological processes
At the end of the course, the student should be able to:

- discuss the role of and the relationships between the main physical, rheological and compositional parameters which govern the eruptive process, and their mutual relationships
- to interpret the volcanic process using an interdisciplinary approach (geological, geochemical, geophysical and petrographical)
- to read and critically discuss scientific papers from the volcanological literature

Classroom lectures on each topic of the program, presentation and discussion of case-studies, direct involvement of the students with the critical reading and discussion of volcanological papers. Final field trip

Oral examination; optional presentation of a topic from the program of the course

Physical and rheological properties of magma: Density, Viscosity: Newtonian, Bingham, pseudoplastic fluids. Yield strength. Main controlling parameters: melt composition, crystal and vesicle content, magmatic volatiles, temperature and pressure. Experimental data.
Magmatic volatiles: types and solubility. Experimental data. Processes of solution of the different species. Methods of measurement in eruptive products.
Physical and dynamical processes in magma chambers.
The process of magma ascent to the surface: Bubble nucleation, growth and evolution. Magma fragmentation.
Evolution of the main physical and rheological parameters during magma ascent

The effusive process. Processes of gas-magma separation during ascent
Different types of lava flows as a function of their rheological properties. Lava flows and lava domes.

The explosive process
Main parameters controlling the physics of atmospheric plumes
Sustained convective columns and tephra fall
Processes of column collapse and generation of pyroclastic density currents
The different types of explosive eruptions
Hawaiian and strombolian eruptions: main physical parameters and associated deposits
Plinian and subplinian eruptions: main physical parameters and associated deposits
Vulcanian eruptions: main physical parameters and associated deposits
Tephra fall. Physics of the dispersal process. Isopach and Isopleth maps: estimation of the main physical parameters of past eruptions
Pyroclastic density currents (PDC)
Ignimbrites, pyroclastic flows and surges. Effects of turbulence, particle concentration, velocity and rheology on PDC
Mechanics of Particle transport: fluidazation vs. turbulence
Mechanics of Particle deposition: en masse vs. aggradational deposition
Hydromagmatic and phreatomagmatic activity
Explosive interaction between magma and water.