Deformation Pattern of the Northern Sector of the Malta Escarpment (Offshore SE Sicily, Italy): Fault Dimension, Slip Prediction, and Seismotectonic Implications

Abstract

Marine seismic reflection data coupled with on-land structural measurements improve our knowledge about the active deformation pattern of the northern sector of the Malta Escarpment, a bathymetric and structural discontinuity in the near-offshore of Eastern Sicily. As favourably oriented to be reactivated within the Neogene Africa–Europe convergence, it is believed that the Malta Escarpment has a significant role in the recent seismotectonic framework of the Western Ionian Basin and the Hyblean foreland domain of SE Sicily, where some of the largest and most destructive Mediterranean earthquakes are located according to available historical catalogs. Offshore seismic data along with bathymetric grids illuminate the shallow subseafloor setting and allow more accurate mapping of the seafloor expression of previously identified faults in the area. The seismic interpretation and the near-fault sediment pattern analysis provide constraints on fault 3D geometries as well as on their through-time tectonic activity, suggesting also that part of the observed deformation may have been caused by nontectonic processes. Identified faults form currently an E-dipping, roughly N–S trending, and 60 km-long extensional belt deforming the seafloor with a significant displacement amount in the Ionian offshore between Catania and Siracusa. 3-dimensional parameters of faults were then used to derive expected magnitudes and their reactivation propensity. Empirical scaling relationships and forward methods point to a high seismic potential for the detected fault as well as predict the fault slip behavior according to the field-derived differential stress. This combined analysis along with faults displacement measurements pointed out how the longest and most continuous fault could be capable of generating M > 7 seismic events, putting forward strong seismotectonic implications for the adjacent and densely populated Hyblean Plateau. The expected magnitude and the estimated recurrence time interval are compatible with those inferred for large historical earthquakes in the area even if other offshore seismic sources cannot be ruled out.

Relative Sea-Level Rise Scenario for 2100 along the Coast of South Eastern Sicily (Italy) by InSAR Data, Satellite Images and High-Resolution Topography

“…Since the Early-Middle Pleistocene, active faulting has contributed to extensional deformation along the coastal sector of south-eastern Sicily, where NNW-SSE trending normal faults control the Ionian shoreline [40][41][42]. These structures are mostly located offshore and their Quaternary activity is probably associated with the recent reactivation of the Malta Escarpment system [43]. This area is marked by a high level of crustal seismicity that released earthquakes of a magnitude of about 7, such as the destructive events occurred in 1169, 1542 and 1693 [44,45].…”

“…This area is marked by a high level of crustal seismicity that released earthquakes of a magnitude of about 7, such as the destructive events occurred in 1169, 1542 and 1693 [44,45]. The seismogenic sources of these historical events is still debated but they are likely located in the Malta Escarpment, between Catania and Siracusa [36,40,[42][43][44][46][47][48][49]. The last major earthquake (ML 5.4) occurred on December 13,1990 in the Augusta off-shore [50][51][52].…”

“…Due to geodynamic processes, such as the retreating of the subducted Ionian slab [53][54][55] or asthenospheric flow beneath a decoupled crust [56,57], and off-shore normal faulting [43,58], during the Late Quaternary, this area has been affected by regional uplifting. Uplift progressively decreases north of southern Calabria and south of north-eastern Sicily, as shown by flights of marine terraces developed along the coasts [53,[59][60][61].…”

Assessing the rate of crustal extension by 2D sequential restoration analysis: A case study from the active portion of the Malta Escarpment

“…The reactivation of MESC involved the proximal part of a narrow sedimentary basin in the hanging‐wall of the fault system, previously named the ‘turbidite valley’ (see Gutscher et al., 2016 and Figure 1c), and its recent deformation is expressed by a belt of East‐dipping extensional faults cutting across the lower slope of the MESC. Fault activity has led to the development of significant fault‐scarps on the seafloor (Argnani & Bonazzi, 2002, 2005; Bianca et al., 1999) that sometimes exceed heights of 60 m (see Gambino et al., 2021). Holocene slip rates estimated by Gambino et al.…”

Commentary: Deformation Pattern of the Northern Sector of the Malta Escarpment (Offshore SE Sicily, Italy): Fault Dimension, Slip Prediction, and Seismotectonic Implications

“…With the aim to contribute to the understanding of the seismotectonics of SE Sicily, (Gambino et al, 2021) (GAMB hereafter) address the northern sector of the Malta Escarpment by studying a set of marine seismic profiles. They make use of both previously published profiles and some original data; the latter belong to a set of high resolution profiles that were acquired during a project not focussed on the Malta Escarpment.…”