Rheology of the 2006 Plinian and effusive eruption of Tungurahua valcano, Ecuador

• Applicant: Professor Dr. Yan Lavallée
• Subject Area: Palaeontology
• Term: from 2008 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 90990877

The increasingly alarming volcanic crisis at Tungurahua volcano requires eminent, thorough understanding of the rheology of the eruptive products. During the recent 2006 Plinian eruptive event, the explosive production of pyroclastic flows simultaneously occurred with the extrusion of a lava flow. Such contrasting cogenetic eruption styles are usually observed at basaltic volcanoes fed by complex plumbing systems, but not at stratovolcanoes built from a simple pipe-like conduit. We hypothesise that two different magma batches with accordingly different Theological properties likely caused this cogenetic eruption. We propose a series of Theological tests and chemical analyses in order to systematically constrain the rheology of Tungurahua magmas. This work aims to (1) describe the geochemistry and the physical characteristics of the 2006 eruptive products, (2) determine the volatile content present in the melt phase (in the chamber and upon eruption), and (3) study the viscosity of the magma under varied stress conditions to understand why only parts of the magma crossed the ductile-brittle transition and formed pyroclastic flows, while the counterparts produced a lava flow.

• DFG Programme: Research Grants
• International Connection: Canada, Ecuador, USA
• Participating Persons: Professor Dr. Jonathan Castro; Professor Dr. Donald Bruce Dingwell; Professor Minard Hall; Dr. Kai-Uwe Hess; Dr. Patricia Mothes; Professor Dr. Kelly Russell