Southern Italy Rising Up to 10 Times Faster Than Thought as Tectonic Slab Tears Beneath Calabria

University of Oregon geologist Becky (Rebecca) Dorsey and colleagues found that high- elevation marine terraces in southern Calabria, Italy (up to ~1,000 m or 3,300 ft above sea level), are rising 5– 10 times faster than previously estimated, linked to an active tear in the Ionian slab beneath the region.

In 2025 fieldwork, a UO- led team sampled sands from these step- like marine terraces along the Siculo- Calabrian rift zone (a >100- mile or ~160 km fault belt).

They applied luminescence dating, previously avoided at such heights because the terraces were thought to be ~1 million years old and beyond the method’s range.

The samples yielded a weighted mean burial age of about 118.8 ± 8.7 thousand years (ka). Combined with mapping and fault morphology, this indicates the terraces are erosional remnants of a single, once- continuous surface that has been rapidly deformed and uplifted.⁠

Calculated uplift rates range from <1 to >12 mm per year, with active normal-fault throw rates of 0.8– 4.2 mm/yr, much faster than earlier long- term estimates based on the older assumed ages.

The rapid post-~120 ka uplift is interpreted as an ongoing isostatic response to tearing of the Ionian slab (an oceanic segment of the African plate) directly under southern Calabria, rather than slower, more uniform processes.⁠

The results, published 6 November 2026 in Communications Earth & Environment, challenge prior models of the terraces and improve constraints for seismic- hazard assessment in this active region.

Insights into slab dynamics here may also inform understanding of other subduction zones, such as Cascadia.⁠

Related earlier work by Dorsey and others (using ⁴⁰Ar and ³⁹Ar dating) already suggested the highest terraces are younger than ~0.5 Ma (roughly half the widely cited ~1 Ma age), implying long- term average uplift >2.5 mm/yr; the new luminescence data refine the recent, faster rates.

Slab tear (or slab tearing and break- off) is a geodynamic process in which a subducting oceanic plate (the “slab”) ruptures and partially or fully detaches from the rest of the lithosphere.

This commonly occurs in subduction zones that experience rollback, oblique collision, or a transition from oceanic to continental subduction.

How the mechanism works

1. Subduction and density contrast
   Dense oceanic lithosphere sinks into the mantle under its own weight (slab pull). When lighter continental lithosphere begins to enter the trench, or when the slab is stretched by rapid trench retreat (rollback), tensile stresses build up inside the slab.
2. Initiation of the tear
   A rupture nucleates, often near the ocean– continent transition or at a pre-existing weak zone. The tear can propagate:
   • Vertically (through the thickness of the slab), creating a “window”.
   • Laterally (along the strike of the subduction zone), allowing the tear to lengthen over time.
3. Propagation and detachment
   Once the tear advances, the detached portion of the slab continues to sink independently. Mantle material (asthenosphere) can flow through the gap (toroidal flow around the torn edges). The remaining attached segment may continue to subduct or experience further tearing.
4. Surface response– isostatic rebound
   Removal of the dense slab load beneath the overriding plate causes the crust above to rise rapidly (isostatic uplift). Predicted rates for this transient phase are typically 5– 14 mm/yr over timescales of a few hundred thousand years or less, much faster than the longer- term rates produced by other processes such as crustal thickening or steady mantle flow.

Application to southern Calabria and the Ionian slab

In the Calabrian Arc (southern Italy):

• The Ionian slab (an oceanic remnant of the African plate) has been retreating southeastward for millions of years, opening the Tyrrhenian Sea behind it.
• Tomographic and seismic data indicate that slab tearing is already complete beneath the southern Apennines, northern Calabria, and northeast Sicily.
• A ~50– 100 km segment remains (or was until recently) more continuous beneath southern Calabria. Evidence points to an active, southward-propagating tear under this region.
• The high -elevation marine terraces dated at ~119 ka record uplift rates of up to ~12 mm/yr. These rates match the rapid, short- lived isostatic rebound expected from ongoing slab tearing and unloading, rather than slower, longer-lived processes such as toroidal mantle flow alone.

In short, the tear removes a heavy “anchor” from beneath the crust, allowing the surface to spring upward quickly. This produces the fast, transient uplift documented in the southern Calabria study and helps explain the region’s elevated seismic hazard, as the same process drives active normal faulting.

The same style of slab tearing and rebound is inferred in other subduction systems worldwide where similar rapid topographic growth is observed.

Rapid transient uplift driven by active slab tear, southern Calabria, Italy

Southern Italy preserves a well-studied record of deformation and uplift related to migrating oblique collision, trench retreat, and tearing of subducted ocean slabs. However, the surface expression of these processes is incompletely understood due to a lack of reliable ages for marine terraces >200 m above sea level. Here we use luminescence methods to date marine terrace sands from 118 to 955 m elevation in southern Calabria and interpolate the results with surface mapping. Burial ages overlap across the full range of sampled elevations with a weighted mean of 118.8 ± 8.7 thousand years before present. Calculated uplift rates vary from <1 to ~12 mm yr⁻¹ and throw rates on active normal faults are 0.8–4.2 mm yr⁻¹. We infer that rapid uplift is an ongoing isostatic response to active tearing in the Ionian slab, consistent with recent geophysical observations and predictions of geodynamic models. These results are useful for assessment of geohazards in southern Calabria and northeast Sicily, one of the highest seismic risk areas in the Mediterranean region.

Key findings

• Luminescence dating (single- grain post- infrared infrared stimulated luminescence on K- feldspar) of sands from marine terraces at elevations of ~107– 1040 m asl yields overlapping burial ages with a weighted mean of 118.8 ± 8.7 ka.
• The terraces are interpreted as erosional remnants of a single, once- continuous deformed surface that has been differentially uplifted and faulted.
• Time- averaged uplift rates calculated from the mean age and elevations range from <1 to ~12 mm yr⁻¹ (commonly reported in related coverage as 5– 10 times faster than earlier long- term estimates based on ~1 Ma ages for the highest terraces).
• Active normal- fault throw rates are 0.8– 4.2 mm yr⁻¹.
• The rapid post-~120 ka uplift is best explained as ongoing isostatic rebound from active tearing of the Ionian slab (an oceanic segment of the African plate) beneath southern Calabria, rather than slower processes such as toroidal mantle flow. This is consistent with geophysical data and geodynamic models predicting faster rates (5– 14 mm yr⁻¹) over shorter timescales (<500 kyr) for slab- breakoff unloading.⁠

The work integrates new luminescence ages with surface mapping, fault- zone morphology, and prior constraints (including evidence that high terraces are <0.48– 0.50 Ma).

It improves understanding of mantle- driven surface processes and seismic hazards in the Siculo- Calabrian rift zone.

A PDF download is available from the Nature page. Let me know if you’d like more details on methods, figures, specific rates, or related papers.

Journal: Communications Earth & Environment, volume 7, Article number: 858 (2026)

DOI: 10.1038/s43247-026-04207-2

Published: 6 November 2026, Open access

Authors: Rebecca J. Dorsey,
Nathan D. Brown,
Sergio G. Longhitano,
Marco Meschis,
Domenico Chiarella &
Charles P. Ogle