Abstract

Subducting plates can follow quite different paths in their life times. While some sink straight through the upper into the lower mantle, others appear to stall in the mantle transition zone above 660 km depth. Geodynamicists have long puzzled about what controls these different styles of behaviour, especially because there appear to be correlations between sinking or stalling with faster or slower plate motions and mountain building or ocean basin formation, respectively. In the long run, how easily slabs sink through the transition zone controls how efficiently material and heat are circulated in the mantle. Many mechanisms have been proposed for the variable slab transition-zone interaction. We recently reviewed the geodynamic and observational literature and combined these insights with those from our own set of mechanical and thermo-mechanical subduction models. This effort shows that not one single mechanism, but an interplay of several mechanisms is the likely cause of the observed variable subduction behaviour.

Saskia is a reader in Geophysics at Imperial College and the director of the Imperial Centre for Geohazards. With her students and postdocs, she has a 25+ year long track record in subduction research, including: shallow and deep subduction earthquakes, subduction related seismic hazard assessment with seismicity and geodetic data, subduction evolution based on plate reconstructions, earthquakes, tectonic data and seismic tomography. In addition, she has done pioneering work on the dynamic interpretation of seismic structure for plates, plumes and mantle convection.