Chapter 14 - Subduction Zones: A Short Review

Abstract

Listen

Translate article

Subduction zones are locations on Earth where the oceanic material of one tectonic plate dives below the material (oceanic or continental) of another tectonic plate into the mantle. They are the most complex and dramatic tectonic features on our home planet and have been the subject of intense investigations, some of which pre-date the advent of the theory of plate tectonics. This contribution provides a short review of the science of subduction zones, discusses and reviews the geometry, kinematics and dynamics of subduction zones, and provides an overview and data compilation for the 28 subduction zones that are currently active on Earth. Most of these subduction zones are characterized by four common, and most conspicuous features, namely a deep-sea trench (21 out of 28), a magmatic arc (23), a Wadati–Benioff zone (22), and a slab geometry in seismic tomography (25). Apart from these four general commonalities and several other characteristics that are less ubiquitous, subduction zones show major variability in appearance and behavior. Earlier investigations have proposed that, among others, subduction zone width or subducting plate age exerts a primary control on this variability. The current contribution presents a global set of observational constraints to investigate the role of width and age on six subduction zone parameters (subducting plate velocity, trench velocity, subduction partitioning, overriding plate deformation rate, slab dip angle, and maximum earthquake magnitude). The results show that correlations for slab width are systematically stronger than for plate age, implying a more significant control of slab width on subduction dynamics, which is consistent with earlier geodynamic modeling efforts and scaling formulations. Considering the more dominant role of slab width, and the subordinate role of subducting plate age, it is here proposed to step away from the age-based subduction zone classification of Mariana-type and Chilean-type subduction zones. It is further proposed that a more meaningful classification is based on slab width and subduction zone size, although admittedly still relatively simplistic, particularly as it ignores the time-evolving aspect of subduction zones. In this classification, Scotia-type subduction zones represent narrow subduction zones with rapid trench retreat, slow subducting plate motion, a steep slab, backarc extension, and absence of giant earthquakes. South American-type subduction zones stand for wide subduction zones with slow trench retreat or slow trench advance, fast subducting plate motion, a gentle-dipping slab, backarc shortening, and occurrence of giant earthquakes.