From Past To Present Roll-Back Subduction: How Slab Dynamics Drive Trench-Parallel and Trench-Perpendicular Deformation, and Related Seismic and Volcanic Hazards

Subduction systems are key geodynamic elements in plate tectonics that develop in converging settings when a dense oceanic lithosphere initiates to underthrust a continental one. Upper and lower plates surrounding an active subduction zone are typically involved in severe deformation, resulting primarily in trench-parallel orogenic belts. Volcanic arcs, as well as extensional Back and compressional Fore-Arc basin systems typically form around a subduction zone, depending on how steep the descending slab is. Along with the straightforward sinking of oceanic lithosphere, other geodynamics processes can take place, including slab roll-back, slab detachment, and slab lateral tearing. According to a tectonic perspective, these processes and the subduction-induced mantle flow make subduction zones the most complex regions on Earth.

Since there is still disagreement over the kinematic linkages between sub-crustal processes and surface deformation response as well as how these processes may interact spatially, we propose this research topic to highlight the state of the art and scientific advancements in understanding subduction zones, particularly those occurring in the Mediterranean region (i.e., Gibraltar, Calabria, Adria, and the Hellenic subduction). For instance, slab rollback can occur if the oceanic basin detaches from the adjacent (commonly continental) lithosphere domains via subvertical tear. Recent works pointed out that subvertical tear faults, known as “STEP” faults, have developed at the edges of many subduction zones worldwide following slab retreating and narrowing. In still active subductions, slab-edge faults are marked by intense seismic activity even if it is not always clear how deformation is transferred from the deeper setting (up to 100 km) to the overriding upper plate. Similar to this, little is known about the causes of slab-edge volcanism (e.g., Mt. Etna in Eastern Sicily) and how magma can differentiate in relation to slab dynamics, especially in correspondence of incipient trench-parallel breakoff gateway between supra-subduction mantle wedge and lower plate mantle. Furthermore, foreland-wards trench migration following slab retreat and tearing can leads to tectonic inversion and uplift of previously extended regions. Subduction zones, on the other hand, are the sites of intense deformation and their evolution may influence the geodynamic of surrounding regions for hundreds of km. Both past and ongoing subductions provide a natural laboratory for a variety of geological processes ranging from Earth interior to surface. Natural hazards may arise as a result of the geological liveliness of the active systems, and for those countries facing subduction zones, understanding these threats is crucial.

We welcome submissions including Original Research, Reviews, Methods, and other article types of contributions suited for this topic. We particularly encourage (but are not limited to) contributions of the following issues:
• Geological and Geophysical observations about the slab structure and tectonic evolution of trench-parallel orogenic belts;
• Field and offshore Geological and Geophysical studies in the upper plate and particularly along slab edges;
• Geodetic measurements of active processes along subduction zones;
• Seismological signature of a slab and earthquakes distribution along subduction zones;
• Geochemical evolution of Island arc and slab edge volcanism;
• Analog or numerical modeling of tectonic mechanisms and topographic evolution around subduction zones.