Transtension at the Northern Termination of the Alfeo-Etna Fault System (Western Ionian Sea, Italy): Seismotectonic Implications and Relation with Mt. Etna Volcanism

Abstract

Offshore data in the western Ionian Sea indicate that the NW–SE-trending dextral shear zone of the Alfeo-Etna Fault System turns to the N–S direction near the Ionian coastline, where the extensional Timpe Fault System is located. Morpho-structural data show that NW–SE-trending right-lateral strike-slip faults connect the Timpe Fault System with the upper slope of the volcano, where the eruptive activity mainly occurs along the N–S to NE–SW-trending fissures. Fault systems are related to the ~E–W-trending extension and they are seismically active having given rise to shallow and low-moderate magnitude earthquakes in the last 150 years. As a whole, morpho-structural, geodetic and seismological data, seismic profiles and bathymetric maps suggest that similar geometric and kinematic features characterize the shear zone both on the eastern flank of the volcano and in the Ionian offshore. The Alfeo-Etna Fault System probably represents a major kinematic boundary in the western Ionian Sea associated with the Africa–Europe plate convergence since it accommodates, by right-lateral kinematics, the differential motion of adjacent western Ionian compartments. Along this major tectonic alignment, crustal structures such as releasing bends, pull-apart basins and extensional horsetails occur both offshore and on-land, where they probably represent the pathway for magma uprising from depth.

Faulting, sediment loading, and flow of underlying ductile units: A case study from the Western Ionian Basin Offshore Eastern Sicily

“…The turbidite basin is internally deformed by extensional tectonics (Gutscher et al, 2016;Gambino et al, 2021Gambino et al, , 2022b, and has escaped compression related to the CAW front. The advancement in the area (toward the West) of the CAW front was probably inhibited by inherited NE-dipping, Meso-Cenozoic extensional structures bordering the Alfeo Seamount block to the NE (see Maesano et al, 2020).…”

“…6 -(a) Location of seismic lines p202 and Cir-01 in the framework of the Western Ionian Basin (b) Portion of Cir-01 showing the internal subdivision of MES unit (see also Gutscher et al, 2016 and Gambino et al, 2021) (c-d) Comparison and similarity between the sand-box model predicting ductile migration under sediment loading (inverted view) proposed by Rojo et al, (2020), and the line-drawing of Cir-01 profile. (e-f)Comparison between the same sand-box model and the line-drawing of the p202 profile showing the occurrence of uprising material along a distal fault (for the original seismic image of the p202 seeGambino et al, 2022b). This distal fault in the case proposed is only supposed since the analyzed seismic lines does not extend far enough…”

Crustal Structure of Etna Volcano (Italy) From P‐Wave Anisotropic Tomography

“…Although several models were proposed to explain the origin of magma in the mantle and its pathways through the crust (e.g., Barberi et al., 1973; Doglioni et al., 2001; Firetto Carlino et al., 2019; Gambino et al., 2022; Gvirtzman & Nur, 1999; Neri et al., 2018; Tanguy et al., 1997), how Etna has formed is still a debated topic, because a continental collisional setting is quite atypical for the emplacement of such an active basaltic volcano. However, over the last 20 years, seismological studies have provided an increasing number of details on Etna crustal structure.…”

The enigmatic 1693 AD tsunami in the eastern Mediterranean Sea: new insights on the triggering mechanisms and propagation dynamics

“…Large blue arrows indicate the GPS vectors (see 14 – 16 , modified after Gambino et al 26 ) in the lower plate of the collisional system whereas small blue arrows is the resultant extension in the Western Ionian Basin. AFS, Alfeo Fault System 17 , 18 ; AEF, Alfeo-Etna Fault 19 ; ( b ) main tectonic structures of Western Ionian basin. NAF, North Alfeo Fault; SAF, South Alfeo Fault (modified after Gambino et al 20 ).…”