Fig. 12

Relationship between the seismic, transition, and creep zones in a subduction zone, and the processes associated with each. The transition zone is the source of tectonic tremor and slow slip and is also the likely locus of underplating, where the metamorphosed sedimentary and volcanic cover of the subducting plate is progressively accreted to the upper plate. This produces significant off-fault deformation, and the active slip surface migrates downwards. In the creep zone, no discrete displacement surface exists; ductile deformation is distributed in a subduction channel between the two plates. Inset shows folds with axial-planar cleavage of the type shown in Fig. 11; we suggest that the hierarchy of structures at different scales can explain LFEs, tremor bursts, and slow slip events