The physics of subduction: statics, kinematics and dynamics
Klaus Regenauer-Lieb^(1,2), Gabriele Morra⁽¹⁾ and Francesca Funiciello⁽³⁾
(1) Institute of Geophysics, ETH Zurich, 8093 Zurich, Switzerland, klaus@tomo.ig.erdw.ethz.ch
(2) CSIRO Perth, Exploration and Mining, Australia
(3) Geological Institute, University Roma Tre, Italy

Abstract:
The subduction problem has been tackled by many different methods. The simplest method is analytical/numerical modelling of static stress equilibrium assuming elastic or elasto-plastic subducting slabs in steady state emphasizing on flexural topography; the next is analytical and fluid dynamic kinematic solutions for corner flow style models emphasizing on temperature solutions derived from kinematically prescribed mantle flow; another is the laboratory analogue modelling of idealized scenarios which display part of the elasto-plastic or visco-elastic dynamics; the last approach is numerical fluid dynamic modelling of stratified viscous fluids aiming to solve dynamical modes of subduction which arise in (1) subduction initiation, (2) interaction with discontinuities (660 km), (3) slab breakoff, (4) solid slab-fluid mantle interaction, (5) deep earthquakes, (6) dynamic topography and lastly (7) interaction of subduction with overriding plate with implications for orogeny. While each method has its individual advantage, we show that fluid dynamical modelling of subduction is chiefly useful for kinematics. However, dynamical fluid dynamic Rayleigh-Taylor modes do not correctly describe the physics of Earth's subduction systems. Elasticity must be incorporated as a key ingredient of subduction. It is non-dissipative and the energetically favoured mode of deformation. Therefore it is essential to investigate dynamic modes (1) to (7) with consideration of elasticity. We will give a few examples highlighting the role of elasticity in dynamics of subduction and juxtapose solution with and without elasticity.