Tectonic Processes in Island Arc Systems

Island arc systems arise where an oceanic plate descends beneath another plate, generating a volcanic chain parallel to a deep-sea trench. Fluids released from the subducting slab induce melting in the overlying mantle wedge, feeding the characteristic arc volcanism. The geometry and rollback of the slab govern trench migration, forearc uplift or subsidence, and back-arc extension. Forearc regions accommodate strain by folding, thrusting and in some cases low-angle normal faulting, while back-arc basins form by rifting and seafloor spreading. Magmatic products evolve through varying degrees of partial melting, fractional crystallisation and crustal assimilation, giving rise to diverse rock types from basalt to trachyte. Seismogenesis at the megathrust interface produces great earthquakes and tsunamis, whereas intra-arc and back-arc faults host both seismic and aseismic slip. Complex interactions among slab fluids, mantle flow and crustal rheology drive long-term crustal growth, mineralisation and landscape development. Understanding these processes is vital for assessing volcanic and seismic hazards, for resource exploration and for reconstructing past plate motions in convergent margins worldwide.

Research from Nature Portfolio

Recent 3D dynamic rupture models of a gently dipping normal fault in an island arc back-arc setting reveal how competing shallow deformation mechanisms control earthquake slip. Synthetic splay faults trap coseismic slip, limiting rupture propagation along the main detachment and altering coastal subsidence patterns and tsunami generation potential. Inelastic deformation in sedimentary hanging walls further localises strain into subplanar shear bands, demonstrating that fault-zone geometry and off-fault plasticity critically modulate seismic hazard.

High-resolution coral uplift chronologies from an island arc trench-front document marked spatial heterogeneity in permanent deformation over the Holocene. Some sites retain cumulative uplift from large thrust events, whereas neighbouring locales experience cycles of uplift and subsidence. This variability points to changes in interplate coupling and strain accumulation along the megathrust, with implications for earthquake recurrence and tsunami risk.

Tectonic Processes in Island Arc Systems publication trend

The graph below shows the total number of articles in tectonic processes in island arc systems across all publications each year (not limited to Nature Index journals).

Technical terms

Subduction zone: A convergent plate boundary where one plate sinks into the mantle beneath another, driving volcanism and seismicity.

Island arc: A curved chain of volcanic islands formed above a subduction zone, reflecting melting of the mantle wedge.

Forearc: The region between the trench and the volcanic arc, often characterised by uplift, sediment accretion and thrust faulting.

Back-arc basin: An area of extension behind a volcanic arc where rifting and seafloor spreading can occur.

Slab rollback: The retreat of a subducting plate’s hinge, causing trench migration, mantle flow changes and arc-trench spacing evolution.

Low-angle normal fault: A near-horizontal extensional fault dipping at less than 30°, which can accommodate crustal extension in forearc or back-arc settings.

References

1. Dueling dynamics of low-angle normal fault rupture with splay faulting and off-fault damage. Nature Communications (2023).
2. Variable Holocene deformation above a shallow subduction zone extremely close to the trench. Nature Communications (2015).
3. The hidden link between dry ankaramitic melts and giant alkalic-type epithermal Au deposits: The Lihir Island example. Geochimica et Cosmochimica Acta (2024).
4. The Dynamics of Unlikely Slip: 3D Modeling of Low‐Angle Normal Fault Rupture at the Mai'iu Fault, Papua New Guinea. Geochemistry Geophysics Geosystems (2022).