Rheology - Magmatology

The need for an adequate understanding of the nature and extent of physico-chemical processes involved in explosive volcanism is considerable.The growth of population centres and industry surrounding active volcanic centres means that, due to the threat to life, property and environment, this need is increasing. In recent years much effort has focused on rhyolitic melts under conditions relevant to explosive volcanism. Modelling of the emplacement and eruption of silicic domes is still hampered by the lack of a sufficiently accurate rheological database for multi-phase lavas with crystals and vesicles, and no simple expression can be used to describe their rheology.

Our research group has been involved in rheological studies of magma for the past 20 years. The work has concentrated in 3 major themes:

• simple melts
• multi-component melts

• multi-component magmas

These studies were aimed to reveal the effect of temperature (high and low), pressure, volatiles (e.g. H2O, F, Cl), redox state of iron, crystals (for small crystal contents), and bubbles on the flow behavior of melts and magmas. Ongoing work is to incorporate the effects of non-Newtonian flow behavior due to a) crystalcontent, b) viscous heating effects, c) non-Newtonian flow behavior of crystal-free melt. This will be a major advancement in constraining ascent and emplacement models.