TY - JOUR

T1 - Seismotomographic detection of major structural discontinuity in northern Sicily

AU - Totaro, Cristina

AU - Kukarina, Ekaterina

AU - Koulakov, Ivan

AU - Neri, Giancarlo

AU - Orecchio, Barbara

AU - Presti, Debora

PY - 2017/10/1

Y1 - 2017/10/1

N2 - We present the results of tomographic inversion computed with the use of the LOTOS code for Sicily and surroundings, a region of great geodynamic interest located on the Nubia-Europe margin where previous analyses have progressively improved the knowledge of seismic velocity structure without, however, permitting fine detection of tectonic units and structural discontinuities. We used LOTOS's devices for inversion, grid rotation and adaptation to ray density for application to a dataset of 7105 local earthquakes of the period 1990-2012. Our tomographic model highlights a previously undocumented major discontinuity which is located approximately along the northern coast of Sicily and is characterized by a sudden transition from low velocity imbricate thrust sheets and accretionary wedge in mainland Sicily (to the south) to relatively high velocity Tyrrhenian continental crust (to the north). Combining this finding with available geological and geodynamic information, we conclude that this northern Sicily seismic velocity discontinuity, which approximately corresponds to a regional fault system known as Kumeta-Alcantara, may have played a major role in the Miocene to Middle Pliocene, when lithosphere tearing occurred between the Tyrrhenian sea and Sicily in response to trench retreat. The more recent geodynamic settings of northern Sicily and the southern Tyrrhenian can be unravelled from Quaternary geological observations, seismicity and GPS data, which indicate that (i) the northern Sicily discontinuity has ceased to be active in more recent times; and (ii) the reorganized slow convergence of Nubia with respect to Europe is currently accommodated ∼100 km north of Sicily, along the east-trending seismogenic belt enclosing Ustica and the Aeolian Islands.

AB - We present the results of tomographic inversion computed with the use of the LOTOS code for Sicily and surroundings, a region of great geodynamic interest located on the Nubia-Europe margin where previous analyses have progressively improved the knowledge of seismic velocity structure without, however, permitting fine detection of tectonic units and structural discontinuities. We used LOTOS's devices for inversion, grid rotation and adaptation to ray density for application to a dataset of 7105 local earthquakes of the period 1990-2012. Our tomographic model highlights a previously undocumented major discontinuity which is located approximately along the northern coast of Sicily and is characterized by a sudden transition from low velocity imbricate thrust sheets and accretionary wedge in mainland Sicily (to the south) to relatively high velocity Tyrrhenian continental crust (to the north). Combining this finding with available geological and geodynamic information, we conclude that this northern Sicily seismic velocity discontinuity, which approximately corresponds to a regional fault system known as Kumeta-Alcantara, may have played a major role in the Miocene to Middle Pliocene, when lithosphere tearing occurred between the Tyrrhenian sea and Sicily in response to trench retreat. The more recent geodynamic settings of northern Sicily and the southern Tyrrhenian can be unravelled from Quaternary geological observations, seismicity and GPS data, which indicate that (i) the northern Sicily discontinuity has ceased to be active in more recent times; and (ii) the reorganized slow convergence of Nubia with respect to Europe is currently accommodated ∼100 km north of Sicily, along the east-trending seismogenic belt enclosing Ustica and the Aeolian Islands.

KW - Nubia-Eurasia plate boundary

KW - Seismic tomography

KW - Sicily

KW - Structural discontinuity

KW - CALABRIAN ARC REGION

KW - ACTIVE TECTONICS

KW - RECENT TECTONIC REORGANIZATION

KW - SEA

KW - MANTLE

KW - SOUTHERN

KW - TYRRHENIAN SUBDUCTION ZONE

KW - VELOCITY STRUCTURE

KW - structural discontinuity

KW - seismic tomography

KW - LITHOSPHERE

KW - SEISMIC TOMOGRAPHY

UR - http://www.scopus.com/inward/record.url?scp=85026530660&partnerID=8YFLogxK

U2 - 10.3301/IJG.2016.14

DO - 10.3301/IJG.2016.14

M3 - Article

AN - SCOPUS:85026530660

VL - 136

SP - 389

EP - 398

JO - Italian Journal of Geosciences

JF - Italian Journal of Geosciences

SN - 2038-1719

IS - 3

ER -