SCALED ANALOG MODELING AS A POWERFUL TOOL FOR EXPERIMENTAL PLANETARY GEOLOGY (Invited Presentation)

Analog modeling is a widely employed research technique for understanding complex geological structures. Well-understood particulate materials such as sand, glass beads, and clay act as counterparts to brittle geological phenomena, from a single basaltic volcano to an entire rocky or icy mechanical lithosphere; viscoelastic and viscoplastic gels can simulate strain-dependent behavior in, for example, a shallow décollement or even a planet’s mantle. The relation of model to natural materials is achieved through geometric, dynamic, and kinematic scaling, which can be enhanced with dimensionless pi numbers. Subject to the same physical laws as real-world geological processes, scaled analog models show remarkable morphological similitude to nature.

Yet analog modeling is under-utilized in planetary science, with preference commonly given to finite- and discrete-element modeling techniques instead. Although numerical approaches have grown increasingly capable and sophisticated since the 1970s, particularly because of dramatic improvements in computer processing power (and commensurate reductions in cost), these techniques face some intrinsic limitations. For example, finite-element codes cannot reproduce individual failure planes, and discrete-element programs often require considerable processing time for detailed three-dimensional models. Furthermore, the choice of a correct failure criterion is critical to ensuring accurate and meaningful assessments of strain from predicted stress magnitudes and orientations.

In this presentation, we describe how scaled analog models can be brought to bear on a range of planetary geomechanics problems, from gravitational deformation, to regional crustal shortening, to ice shell expansion. Augmented by techniques including particle image velocimetry, high-resolution topographic imaging, and geospatial analytics, physical models help improve our understanding of the mathematical and constitutive relationships behind natural structures. Scaled analog modeling is capable of capturing fundamental mechanical behavior in the natural world without having to parameterize non-linear fault growth, changes to stress fields in response to failure, or non-elastic rheologies, and can then be quantified to strengthen numerical simulations.