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PhD position at Cemagref Grenoble, Lahar research project
From: Jean-Claude Thouret <J.C.Thouret@xxxxxxxxxxxxxxxxxxxxxxx>
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Dear VOLCANOLIST,
This PhD research project on lahars will be funded by the French ANR 'Risknat' project called "Laharisk" for a period of 3 years. The position is to be filled at CEMAGREF in Grenoble (in collaboration with Laboratoire 'Magmas and Volcanoes' in Clermont).
Applications must be sent before 1st November 2009. Details are disclosed below.
Many thanks,
Guillaume Chambon and Jean-Claude Thouret
*PhD Fellowship
Titre: Hydraulic and rheological modeling of lahar flows –
Application to Semeru volcano (Indonesia).
*Cemagref (Grenoble) - ANR French National Research Agency - LMV Laboratoire Magmas et Volcans
A PhD fellowship financed by the French National Agency for Research, in the frame of the project Laharisk, is
available to carry out research on the mechanical modeling of lahars. The PhD will be located at Cemagref
Grenoble (France), in the Snow Avalanche and Torrent Control Research Unit. The work will be supervised by G.
Chambon and D. Laigle from Cemagref, in collaboration with J.-C. Thouret from the Magmas and Volcanoes
Laboratory in Clermont-Ferrand (Blaise Pascal University).
_
Objectives and methods_
Lahars constitute one of the most destructive volcanic phenomena. However, the dynamics of these surges
made of a mixture of water and debris, remains poorly known. Improving the knowledge on the rheological and
hydraulic properties of these flows is thus required, in order to build efficient methods for risk assessment in
highly populated areas. To this aim, in situ data from measurement stations located on the flank of the active
volcano Semeru (Java, Indonesia), which produces several lahars each year, will be acquired in the frame of
Laharisk project. These data will serve as a basis for the modeling to be undertaken in the proposed doctoral
program.
_Two complementary issues will be addressed:_
- Rheometrical analyses on materials sampled in situ (assuming the complete grain-size distribution has been
preserved) or on synthetic, reconstituted materials. These analyses should allow to determine the rheological
behavior of lahar constitutive matrix.
- Hydrodynamic modeling of lahar flows using a 1D or 2D shallow-water approach, well-suited to the simulation
of gravity-driven free-surface surges. Developments will be based on existing codes, but the implementation of
rheological models specific to lahars will be necessary. The processes of bulking and debulking will also have to
be accounted for, at least in a simplified manner, analogously to what is done for other types of geophysical
flows (avalanches, granular flows). The obtained results will be compared and validated against the available
field data: characteristics of natural deposits, in situ measurements within flows (velocity, height, concentration).
A the end, the produced model should allow operational predictions in a context of risk management.
_
Candidate profile_
Solid knowledge in fluid mechanics and numerical methods is required. Good knowledge in rheology and
rheometry of complex fluids, as well as in physical volcanology, would also be appreciated.
_Applications (CV and application letter) should be sent to Guillaume Chambon before 01/11/2009:
guillaume.chambon@xxxxxxxxxxxx
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