Effect of Plate Length on Subduction Kinematics and Slab Geometry: Insights From Buoyancy-Driven Analog Subduction Models

K. Xue*, W. P. Schellart, V. Strak

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


Subduction style is controlled by a variety of physical parameters. Here we investigate the effect of subducting plate length on subduction style using laboratory experiments of time-evolving buoyancy-driven subduction in 3-D space. The investigation includes two experimental sets, one with a lower (~740) and one with a higher (~1,680) subducting plate-to-mantle viscosity ratio (ηSPM). Each set involves five models with a free-trailing-edge subducting plate and variable plate length (20–60 cm, scaling to 1,600–4,800 km), and one model with a fixed-trailing-edge subducting plate representing an infinitely long plate. Through determining the contact area between subducting plate and underlying mantle, plate length affects the resistance to trenchward motion of the subducting plate and thus controls the partitioning of the subduction velocity (vS) into the subducting plate velocity (vSP) and trench velocity (vT). This subduction partitioning thereby determines the subduction style by controlling the dip angle of the slab tip once it first touches the 660 km discontinuity. The low ηSPM models display two subduction styles. Short plates (≤40 cm) induce a higher subduction partitioning ratio (vSP/vS), promoting trench advance and slab rollover geometries, whereas longer plates (≥50 cm) lead to a lower vSP/vS, producing continuous trench retreat and backward slab draping geometries. In contrast, the high ηSPM models exclusively show trench retreat with draping geometries, as the high ηSPM enables less slab bending before its tip touches the 660 km discontinuity. Our study indicates that future modeling work should consider the effects of plate length on the style and evolution of subduction.

Original languageEnglish
Article numbere2020JB020514
Pages (from-to)1-23
Number of pages23
JournalJournal of Geophysical Research: Solid Earth
Issue number11
Early online date18 Oct 2020
Publication statusPublished - Nov 2020


  • geodynamics
  • plate kinematics
  • slab bending
  • slab dip
  • subduction
  • trench migration


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