Rates of active compressional deformation in central Italy and Sicily: evaluation of the seismic budget

Visini, Francesco; Nardis, Rita de; Lavecchia, Giusy

doi:10.1007/s00531-009-0473-x

Cited by 24 publications

(19 citation statements)

References 54 publications

(94 reference statements)

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“…Frontal thrusting is still seismically active, as indicated by the 1968 Belice Valley destructive earthquake sequence (Monaco et al, 1996;Morelli and Pondrelli, 1998;DISS Working Group, 2010). Accordingly, the seismotectonic processes accommodate active compression at the front of the SFTB and particularly along deep-seated thrust planes (Lavecchia et al, 2007;Visini et al, 2010;Sgroi et al, 2012).…”

Section: Geological Settingmentioning

confidence: 99%

“…blind thrust ramp as the possible seismogenic source for the 1968 Belice earthquake sequence. Accordingly, Lavecchia et al (2007) consider this area as part of a unique regional-scale seismogenic structure (named Sicilian Basal Thrust) which deepens northward from the front and reaches sub-crustal depths (see also Visini et al, 2010;Sgroi et al, 2012). Notwithstanding, these models do not provide precise constraints on the location and geometric character of the seismogenic sources in the area are.…”

Section: Introductionmentioning

confidence: 99%

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Geodetic and geological evidence of active tectonics in south-western Sicily (Italy)

Barreca

Bruno

Cocorullo

et al. 2014

Journal of Geodynamics

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a b s t r a c tIntegrated geological, geodetic and marine geophysical data provide evidence of active deformation in south-western Sicily, in an area spatially coincident with the macroseismic zone of the destructive 1968 Belice earthquake sequence. Even though the sequence represents the strongest seismic event recorded in Western Sicily in historical times, focal solutions provided by different authors are inconclusive on possible faulting mechanism, which ranges from thrusting to transpression, and the seismogenic source is still undefined. Interferometric (DInSAR) observations reveal a differential ground motion on a SW-NE alignment between Campobello di Mazara and Castelvetrano (CCA), located just west of the maximum macroseismic sector. In addition, new GPS campaign-mode data acquired across the CCA alignment documents NW-SE contractional strain accumulation. Morphostructural analysis allowed to associate the alignment detected through geodetic measurements with a topographic offset of Pleistocene marine sediments. The on-land data were complemented by new high-resolution marine geophysical surveys, which indicate recent contraction on the offshore extension of the CCA alignment. The discovery of archaeological remains displaced by a thrust fault associated with the alignment provided the first likely surface evidence of coseismic and/or aseismic deformation related to a seismogenic source in the area. Results of the integrated study supports the contention that oblique thrusting and folding in response to NW-SE oriented contraction is still active. Although we are not able to associate the CCA alignment to the 1968 seismic sequence or to the historical earthquakes that destroyed the ancient Greek city of Selinunte, located on the nearby coastline, our result must be incorporated in the seismic hazard evaluation of this densely populated area of Sicily.

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Section: Geological Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Geodetic and geological evidence of active tectonics in south-western Sicily (Italy)

Barreca

Bruno

Cocorullo

et al. 2014

Journal of Geodynamics

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“…On the basis of evidence from fault plane solution mechanisms of moderate‐to‐large crustal earthquakes ( M w ≥ 4.0, depth ≤ 40 km; Neri et al 2005; Lavecchia et al 2007a; Billi et al 2010; Visini et al 2010), five major geographically and kinematically seismogenic domains may be distinguished in Sicily. They are shown schematically in Fig.…”

Section: Seismotectonic Frameworkmentioning

confidence: 99%

Crustal structure and seismotectonics of central Sicily (southern Italy): new constraints from instrumental seismicity

Sgroi

Nardis

Lavecchia

2012

Geophysical Journal International

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SUMMARY In this paper, we propose a new model of the crustal structure and seismotectonics for central Sicily (southern Italy) through the analysis of the depth distribution and kinematics of the instrumental seismicity, occurring during the period from 1983 to 2010, and its comparison with individual geological structures that may be active in the area. The analysed data set consists of 392 earthquakes with local magnitudes ranging from 1.0 to 4.7. We defined a new, detailed 1‐D velocity model to relocate the earthquakes that occurred in central Sicily, and we calculated a Moho depth of 37 km and a mean VP/VS ratio of 1.73. The relocated seismic events are clustered mainly in the area north of Caltanissetta (e.g. Mainland Sicily) and in the northeastern sector (Madonie Mountains) of the study area; only minor and greatly dispersed seismicity is located in the western sector, near Belice, and along the southern coast, between Gela and Sciacca. The relocated hypocentral distribution depicts a bimodal pattern: 50 per cent of the events occur within the upper crust at depths less than ∼16 km, 40 per cent of the events occur within the middle and depth crust, at depths between 16 and 32 km, and the remaining 10 per cent occur at subcrustal depths. The energy release pattern shows a similar depth distribution. On the basis of the kinematic analysis of 38 newly computed focal plane solutions, two major geographically distinct seismotectonic domains are distinguished: the Madonie Mountain domain, with prevalent extensional and extensional‐oblique kinematics associated with upper crust Late Pliocene–Quaternary faulting, and the Mainland Sicily domain, with prevalent compressional and compressional‐oblique kinematics associated with thrust faulting, at mid to deep crust depth, along the north‐dipping Sicilian Basal Thrust (SBT). The stress inversion of the Mainland Sicily focal solutions integrated with neighbouring mechanisms available in the literature highlights a regional homogeneous compressional tensor, with a subhorizontal NNW–SSE‐striking σ1 axis. In addition, on the basis of geodetic data, the Mainland Sicily domain may be attributed to the SSE‐ward thrusting of the Mainland Sicily block along the SBT plane. Seismogenic shearing along the SBT at mid‐crustal depths was responsible for the unexpected Belice 1968 earthquake (Mw 6.1), with evident implications in terms of hazard assessment.

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“…1) (e.g., Pondrelli et al 2006, and references therein) show the presence of two different seismogenic behaviors at shallow depth (i.e., above 30 km) west and east of the central Aeolian Islands. The boundary between these two zones is commonly identified with the northern prolongation of the Tindari-Letojanni fault system (Billi et al 2006) toward the Aeolian Islands, where a broad belt of compressional or transpressional structures has been recognized Visini et al 2009) in the hagingwall of the southern Tyrrhenian subduction zone (e.g., Chiarabba et al 2008). This compressional belt has been also interpreted as the indication for the inception of a new subduction zone along the southern Tyrrhenian (Billi et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Coexisting tectonic settings: the example of the southern Tyrrhenian Sea

Cuffaro

Riguzzi

Scrocca

et al. 2011

Int J Earth Sci (Geol Rundsch)

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We performed geodetic strain rate analyses in southern Italy, using new GPS velocities. Two-dimensional strain and rotation rate fields were estimated and results show that most of the shortening is distributed in the northern Sicily offshore. Extension becomes more evident and comparable with shortening on the eastern side of the same margin, and greater in the eastern Sicily offshore. Principal shortening and extension rate axes are consistent with long-term geological features: seismic reflection profiles show both active compressive and extensional faults affecting Pleistocene strata. We show evidence for contemporaneous extension and transtension in the Cefalu Basin. Combining geodetic data and geological features point to the coexistence of independent geodynamic processes, i.e., the active E-W backarc spreading in the hangingwall of the Apennines subduction zone and shortening along the southern margin of the Tyrrhenian backarc basin operated by the NNW-motion of Africa relative to Eurasia

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Rates of active compressional deformation in central Italy and Sicily: evaluation of the seismic budget

Cited by 24 publications

References 54 publications

Geodetic and geological evidence of active tectonics in south-western Sicily (Italy)

Geodetic and geological evidence of active tectonics in south-western Sicily (Italy)

Crustal structure and seismotectonics of central Sicily (southern Italy): new constraints from instrumental seismicity

Coexisting tectonic settings: the example of the southern Tyrrhenian Sea

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