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Deep view of the Subduction-Transform Edge Propagator (STEP) fault in the Calabrian Subduction Zone
Type
Poster session
Language
English
Obiettivo Specifico
2T. Tettonica attiva
Status
Unpublished
Conference Name
Issued date
April 21, 2016
Conference Location
Vienna (AT)
Sponsors
Multichannel seismic reflection surveys in the Ionian sea are kindly provided by Spectrum under a Confidentiality Agreement (CA-60) with INGV. CROP seismic profiles are provided by CNR-ISMAR.
The bathymetric Digital Terrain Model is derived from the EMODnet Bathymetry portal - http://www.emodnet-bathymetry.eu.
Midland Valley Ltd is acknowledged for making available the Move software to INGV under Academic Software Initiative (ASI).
Ornella Curatolo is acknowledged for the graphic design (http://www.ornellaflora.com)
This poster benefits from the financial support of RITMARE, Porto Empedocle, and PON Massimo Projects
The bathymetric Digital Terrain Model is derived from the EMODnet Bathymetry portal - http://www.emodnet-bathymetry.eu.
Midland Valley Ltd is acknowledged for making available the Move software to INGV under Academic Software Initiative (ASI).
Ornella Curatolo is acknowledged for the graphic design (http://www.ornellaflora.com)
This poster benefits from the financial support of RITMARE, Porto Empedocle, and PON Massimo Projects
Abstract
The Calabrian Subduction Zone plays a key role in the evolution of the central Mediterranean in the framework of
the convergence between Africa and Europe.
Here, the remnants of the World’s oldest oceanic crust form a narrow NW-dipping slab passively subducting
beneath the Calabrian Arc.
Recently published high-resolution seismic profiles and bathymetric data of the western Ionian Sea highlight
the presence of a NNW-SSE faulting system connected with a series of Plio-Pleistocene syn-tectonic basins.
These features are correlated with the recent activity of a major NNW-SSE deformation zone confining the active
subduction to the SW and interpreted as a Subduction-Transform Edge Propagator (STEP) fault.
The goal of this work is to jointly reconstruct the geometry of the STEP fault and the subduction interface in its
surroundings.We use multichannel seismic profiles acquired in the southwestern part of the Calabrian accretionary
wedge to focus on the STEP fault geometry at depth and to analyse its relationships with shallow deformation
features.
The quantitative analysis and enhancement of seismic data provided an accurate image of the internal structure
of the accretionary wedge at various depths, showing growth strata in the Plio-Pleistocene succession and major
discontinuities in the lower crust.
Our results depict a main subvertical, slightly east-dipping, lithospheric fault cutting the oceanic crust down to
the Moho, and a rich set of associated secondary synthetic and antithetic faults. This picture also provides new
insights on the STEP fault propagation mechanism.
In addition, the tridimensional correlation of the STEP fault occurrences in various seismic profiles provides
a preliminary scheme of its segmentation and highlights the relationships of this master fault with other main
structural elements of the Calabrian Arc and Eastern Sicily, including some of the faults deemed to be responsible
for major historical earthquakes in the area.
the convergence between Africa and Europe.
Here, the remnants of the World’s oldest oceanic crust form a narrow NW-dipping slab passively subducting
beneath the Calabrian Arc.
Recently published high-resolution seismic profiles and bathymetric data of the western Ionian Sea highlight
the presence of a NNW-SSE faulting system connected with a series of Plio-Pleistocene syn-tectonic basins.
These features are correlated with the recent activity of a major NNW-SSE deformation zone confining the active
subduction to the SW and interpreted as a Subduction-Transform Edge Propagator (STEP) fault.
The goal of this work is to jointly reconstruct the geometry of the STEP fault and the subduction interface in its
surroundings.We use multichannel seismic profiles acquired in the southwestern part of the Calabrian accretionary
wedge to focus on the STEP fault geometry at depth and to analyse its relationships with shallow deformation
features.
The quantitative analysis and enhancement of seismic data provided an accurate image of the internal structure
of the accretionary wedge at various depths, showing growth strata in the Plio-Pleistocene succession and major
discontinuities in the lower crust.
Our results depict a main subvertical, slightly east-dipping, lithospheric fault cutting the oceanic crust down to
the Moho, and a rich set of associated secondary synthetic and antithetic faults. This picture also provides new
insights on the STEP fault propagation mechanism.
In addition, the tridimensional correlation of the STEP fault occurrences in various seismic profiles provides
a preliminary scheme of its segmentation and highlights the relationships of this master fault with other main
structural elements of the Calabrian Arc and Eastern Sicily, including some of the faults deemed to be responsible
for major historical earthquakes in the area.
References
Bird, P. (2003). An updated digital model of plate boundaries, Geochem. Geophys. Geosyst., doi: 10.1029/2001GC000252.
DISS Working Group (2015). Database of Individual Seismogenic Sources (DISS), Version 3.2.0. http://diss.rm.ingv.it/diss/,
DOI:10.6092/INGV.IT-DISS3.2.0.
Gallais, F., et al. (2012), Two-stage growth of the Calabrian accretionary wedge in the Ionian Sea (Central
Mediterranean): Constraints from depth‐migrated multichannel seismic data, Mar. Geol., doi:10.1016/j.margeo.2012.08.006.
Govers R., and Wortel M.J.R. (2005). Lithosphere tearing at STEP faults: Response to edges of subduction zones. Earth and
Planetary Science Letters, doi: 10.1016/j.epsl.2005.03.022.
Gutscher, M. A., et al. (2015), Tectonic expression of an active slab tear from high‐resolution seismic and bathymetric
data offshore Sicily (Ionian Sea), Tectonics, 10.1002/2015TC003898.
Polonia, A., et al. (2011), The Calabrian Arc subduction complex in the Ionian Sea: Regional architecture, active
deformation, and seismic hazard. Tectonics, doi:10.1029/2010tc002821.
DISS Working Group (2015). Database of Individual Seismogenic Sources (DISS), Version 3.2.0. http://diss.rm.ingv.it/diss/,
DOI:10.6092/INGV.IT-DISS3.2.0.
Gallais, F., et al. (2012), Two-stage growth of the Calabrian accretionary wedge in the Ionian Sea (Central
Mediterranean): Constraints from depth‐migrated multichannel seismic data, Mar. Geol., doi:10.1016/j.margeo.2012.08.006.
Govers R., and Wortel M.J.R. (2005). Lithosphere tearing at STEP faults: Response to edges of subduction zones. Earth and
Planetary Science Letters, doi: 10.1016/j.epsl.2005.03.022.
Gutscher, M. A., et al. (2015), Tectonic expression of an active slab tear from high‐resolution seismic and bathymetric
data offshore Sicily (Ionian Sea), Tectonics, 10.1002/2015TC003898.
Polonia, A., et al. (2011), The Calabrian Arc subduction complex in the Ionian Sea: Regional architecture, active
deformation, and seismic hazard. Tectonics, doi:10.1029/2010tc002821.