Tectonic expression of an active slab tear from high-resolution seismic and bathymetric data offshore Sicily (Ionian Sea)

Type Article
Date 2016-01-06
Language English
Author(s) Gutscher Marc-Andre1, Dominguez Stephane2, Mercier De Lepinay Bernard3, Pinheiro Luis4, 5, Gallais Flora1, 6, Babonneau Nathalie1, Cattaneo AntonioORCID6, Le Faou Yann7, Barreca Giovanni8, Micallef Aaron9, Rovere Marzia10
Affiliation(s) 1 : Univ Brest, CNRS, IUEM, Domaines Ocean, Plouzane, France.
2 : Univ Montpellier 2, CNRS, Geosci Montpellier, Montpellier, France.
3 : Univ Nice, CNRS, GeoAzur, Valbonne, France.
4 : Univ Aveiro, Dept Geosci, P-3800 Aveiro, Portugal.
5 : Univ Aveiro, CESAM, P-3800 Aveiro, Portugal.
6 : IFREMER, Inst Carnot Geosci Marines, Ifremer EDROME Geosci Marines, Plouzane, France.
7 : Serv Hydrog & Oceanog Marine, Brest, France.
8 : Univ Catania, Dept Biol Geol & Environm Sci, Catania, Italy.
9 : Univ Malta, Dept Geosci, Msida, Malta.
10 : CNR, Inst Marine Sci, I-40126 Bologna, Italy.
Source Tectonics (0278-7407) (Amer Geophysical Union), 2016-01-06 , Vol. 35 , N. 1 , P. 39-54
DOI 10.1002/2015TC003898
WOS© Times Cited 37
Keyword(s) slab tear, subduction, Mediterranean, bathymetry, seismics, active faults
Abstract Subduction of a narrow slab of oceanic lithosphere beneath a tightly curved orogenic arc requires the presence of at least one lithospheric scale tear fault. While the Calabrian subduction beneath southern Italy is considered to be the type example of this geodynamic setting, the geometry, kinematics and surface expression of the associated lateral, slab tear fault offshore eastern Sicily remain controversial. Results from a new marine geophysical survey conducted in the Ionian Sea, using high-resolution bathymetry and seismic profiling reveal active faulting at the seafloor within a 140 km long, two-branched fault system near Alfeo Seamount. The previously unidentified 60 km long NW trending North Alfeo Fault system shows primarily strike-slip kinematics as indicated by the morphology and steep-dipping transpressional and transtensional faults. Available earthquake focal mechanisms indicate dextral strike-slip motion along this fault segment. The 80 km long SSE trending South Alfeo fault system is expressed by one or two steeply dipping normal faults, bounding the western side of a 500+ m thick, 5 km wide, elongate, syntectonic Plio-Quaternary sedimentary basin. Both branches of the fault system are mechanically capable of generating magnitude 6-7 earthquakes like those that struck eastern Sicily in 1169, 1542, and 1693.
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Gutscher Marc-Andre, Dominguez Stephane, Mercier De Lepinay Bernard, Pinheiro Luis, Gallais Flora, Babonneau Nathalie, Cattaneo Antonio, Le Faou Yann, Barreca Giovanni, Micallef Aaron, Rovere Marzia (2016). Tectonic expression of an active slab tear from high-resolution seismic and bathymetric data offshore Sicily (Ionian Sea). Tectonics, 35(1), 39-54. Publisher's official version : https://doi.org/10.1002/2015TC003898 , Open Access version : https://archimer.ifremer.fr/doc/00318/42924/