[Hess] Viscous flow of magmas from Unzen volcano, Japan - Implications for magma ascent and emplacement

German Title: Viscous flow of magmas from Unzen volcano, Japan - Implications for magma ascent and emplacement

Abbreviation: 193

Current Status: completed

Main Applicant:Dr. Kai-Uwe Hess

Resources Recipient

Other Persons

Dr. Benoit Cordonnier

Conveyor Begin:
Conveyor End:
Conveyor Duration:
Year: 2005


The lack in understanding the flow behaviour of ascending highly viscous conduit magmas is a major drawback in forecasting explosive volcanic eruptions. Due to the very recent development of a unique high-load, high-temperature deformation apparatus it is now, for the first time, possible to determine the effective non-Newtonian viscosity of rhyolitic multi-phase magmas at strain rates actually occurring prior to and during volcanic eruptions. This opportunity comes when cores from a section of Unzen’s conduit were recently acquired. Taken together, the new technique and the new sample availability provide a unique opportunity to advance the rheological understanding of Unzen. The new data will enable the elaboration of complete volcanic eruption models at Unzen. Such models have important implications for the interpretation of (a) shallow volcanic earthquakes (e.g. low frequency events) and their potential use as indicators for near-future volcanic eruptions, (b) self-sealing mechanisms of the Unzen conduit, and (c) the poorly understood displacement mechanism of Unzen lava lobes, potentially indicative of non-Newtonian flow behaviour.

Related Publications

Cordonnier, B., Hess, K. U., Lavallee, Y., Dingwell, D. B. (2009). "Rheological properties of dome lavas: Case study of Unzen volcano" Earth and Planetary Science Letters 279 p263-272

Vetere, Francesco, Behrens, Harald, Schuessler, Jan A., Holtz, Francois, Misiti, Valeria, Borchers, L. (2008). "Viscosity of andesite melts and its implication for magma mixing prior to Unzen 1991–1995 eruption" Journal of Volcanology and Geothermal Research 275 p208-217

Hess, Kai-Uwe, Cordonnier, Benoit, Lavallée, Yan, Dingwell, Donald B. (2008). "Viscous heating in rhyolite: An in situ experimental determination" Earth and Planetary Science Letters 275 p121-126

K.-U. Hess, B. Cordonnier, Y. Lavallée, D. B. Dingwell (2007). "High-load, high-temperature deformation apparatus for synthetic and natural silicate melts" Review of Scientific Instruments 78 p075102

Lavallée, Yan, Hess, Kai-Uwe, Cordonnier, Benoit, Dingwell, Donald Bruce (2007). "Non-Newtonian rheological law for highly crystalline dome lavas" Geology 35 (9) p843-846