. Anders Malthe-Sørenssen
     

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Volcanic basin processes

We address the effect of magmatic intrusions into sedimentary basins. The project consists of several component: studies of the emplacement processes itself, studies of the cooling and solidification of the intrusion, studies of the processes in the surrounding areole of thermally perturbed hostrock, studies of the formation of high-permeability pathways, pipes, leading the high-pressured fluids to the surface, and studies of the environmental consequences of large releases of greenhouse gases or environmental poisons.

The project is integrated, combining field and seismic studies, laboratory experiments, numerical modeling on many scales, and theory, and is strongly cross-disciplinary, including strong groups in physics, geology, and geophysics. The project has also a strong industrial component. More information can be found on the website for the project, and on the website for Volcan Basin Petroleum Research.

Key reference: Svensen, Planke, Malthe-Sørenssen, Jamtveit, Myklebust, Rassmussen, and Rey. Release of methane from a volcanic basin as a mechanism for initial Eocene global warming. Nature (2004) 429, 542-545.

Fluid-rock systems

The fluid-rock activity focuses on fluid-rock interactions and fluid migration processes. A description of the fluid-rock group activity at Physics of Geological Processes is provided on the web page. Currently, my main interest is in the development of a theory for fracturing accelerated reaction fronts, and its applications to understand for example fluid migration in low-permeability media, stress corrosion, and weathering processes.

Key reference: Jamtveit, Austrheim, Malthe-Sorenssen, Nature, (2000) 408, 75-78.

Brittle deformation processes

Fracturing is a fundamental process affecting the physical properties of solids. Fracture is also an imporatant factor in determining the transport properties and the propagation and reflection of seismic waves in rocks. We study fracturing with particular emphasis on systems with many interacting fractures through field studies, laboratory experiments, numerical models, and theory.

We have developed a numerical model for faulting and fracturing in geological systems that have been developed into a commerical software tool in collaboration with Conoco, now ConocoPhillips.

Key reference: A. Malthe-Sørenssen, T. Walmann, B. Jamtveit, J. Feder, and T. Jøssang. Modeling and characterization of fracture patterns in the Vatnajokull glacier. Geology (1998) 26, 931-934.

Friction

The practical 'laws' of friction were understood in antiquity. However, friction has not been understood in terms of physics: There is no paper in the literature the describes the calculation of the coefficient of friciton - we do not know how to do it.

We study frictional effects in systems of geological relevance, such as the effect of frictional heating in shear zones, and the origin of the friction angle in granular systems. We have also recently studied plastic friction in aluminum extrusion processes in an integrated project funded by Hydro.

Slowly driven processes

Granular systems provided the inspiration for the generic model of self-organized criticality, which was proposed as a mechanism to spontaneously generate fractal structures in space and time. The idea that slowly driven 'sand' piles may indeed be described as self-organized critical systems has been discussed for a long time, and recent experiments have been inconclusive. However, a novel experiment on piles of rice resolved the question: Granular piles may display self-organized critical dynamics, but the behavior is not universal.

Key reference: Frette, Christensen, Malthe-Sørenssen, Feder, Jøssang and Meakin. Avalanche dynamics in a pile of rice. Nature (1996) 379, 49-52.