Sicily, Italy) from GPS Data Geologica Acta: an International Earth Science Journal, Vol

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Geologica Acta: an international earth science journal ISSN: 1695-6133 [email protected] Universitat de Barcelona España

MATTIA, M.; BRUNO, V.; CANNAVÒ, F.; PALANO, M. Evidences of a contractional pattern along the northern rim of the Hyblean Plateau (Sicily, Italy) from GPS data Geologica Acta: an international earth science journal, vol. 10, núm. 1, 2012, pp. 1-8 Universitat de Barcelona Barcelona, España

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Cómo citar el artículo Número completo Sistema de Información Científica Más información del artículo Red de Revistas Científicas de América Latina, el Caribe, España y Portugal Página de la revista en redalyc.org Proyecto académico sin fines de lucro, desarrollado bajo la iniciativa de acceso abierto 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 ARTICLE IN PRESS 9 8 7 6 5 4 3 2 1 .geologica-acta.com o c . a t c a 8 - - a 1 c i , g 2 o 1 l 0 o 2 e g h w. c w r w a 5 M 0 t 7 a , 1 2 0 e 1 0 n 0 i º 0 l N 0 n . o , 5 0 0 e 1 1 l . / b l 4 a o 4 V l 3 i 1 , a . a v A 0 t 1 c A : I a O c D i g o l o e G (Serpelloni et al., 2007) evidence that there is a motion motion a is there that papers evidence 2007) recent al., et Although (Serpelloni 2007). al. et motion Serpelloni Selvaggi, plate and 2004; Nubian D’Agostino 2003; the al., et match Hollestein (e.g. Sicily in African velocities (the GPS stations as at Rift), plate African East Nubian the of west the plate with together Neogene- Sicily moves of most that Eurasia. ~N20°W demonstrated have and studies the Nubia Geodetic between to convergence due Quaternary processes tectonic INTRODUCTION Eurasian frameindicatesthatalarge partoftheplateauisdominatedbya5.4mm/yrnorthward motion. a addition, In 0.14µstrain/yr data. about (InSAR) transition to extensional regime Radar of is acting toward the central Aperture sector of the strain-rate plateau. Synthetic The velocity field referred negative toInterferometric the and maximum geological a both with with agreement Plateau in Hyblean the of rim northern the along of casualties. We have found that the ground deformation pattern clearly defines an area of prevailing contraction in the past (1169 and 1693) that struggled the cities of Catania, Siracusa and Ragusa provoking tens of thousands Eurasia 2) it is very close to the biggest European volcano Mount Etna and and Nubia 3) between it front has collision the been of hit piece by important strong an earthquakes represents it 1) because interest great of is area this northern rim of the Hyblean Plateau from 9 continuous and 23 survey-mode sites. From a geological point of view, In this paper we present the main results inferred from GPS data collected between 1998.00 and 2009.78 along the Correspondingauthor, Tel. +39.95.7165805Fax. +39.95.435801 KEYWORDS Evidences ofacontractionalpatternalongthenorthernrim * Southern Italy is a key area for understanding the the understanding for area key a is Italy Southern Hyblean Plateau.GPS.Activetectonics.Deformation.Geodynamic. Hyblean Plateau(Sicily, Italy)fromGPSdata Piazza Roma2,95123Catania,ItalyMattiaE-mail:[email protected] IstitutoNazionalediGeofisicae Vulcanologia, SezionediCatania 1 M. MATTIA V. BRUNOF. CANNAVÒ M.PALANO 1 * S B A T C A R T al., 2009 for details and references therein). et references and Mattia details see for 2009 1A; al., (Fig. axes thrust compressive NW-SE NNW-SSE and zone with moderate-sized mechanisms offshore focal frequent, having This earthquakes by 1A). (Fig. characterized Ustica is of south convergence Sicily of north and located belt Eurasia-Nubia a north- in absorbed the its be to on appears and (except corner) small is eastern Sicily in internal the deformation that concept a the is Sicily around there the agreement 2008), general of al., et opening (D’Agostino zone the rift internal to Channel in related sites some probably at plate Sicily Nubian the to relative 1 1

1 1

10 12 11 14 13 16 15 18 17 20 19 22 21 24 23 26 25 28 27 30 29 32 31 34 33 36 35 38 37 40 39 42 41 44 43 46 45 48 47 50 49 52 51 54 53 55

2 1 4 3 6 5 8 7 ARTICLE IN PRESS 9 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 ARTICLE IN PRESS 9 8 7 6 5 4 3 2 1 TTIA et al. l a t e A I T AT M . M ) 5 2 0 1 7 0 1 2 0 ( 0 0 8 0 - 0 1 . 5 , 0 ) 1 1 / ( 4 0 4 1 3 1 , . a 0 t 1 c A : I a O c D i g o l o e G 1693) destructive earthquakes (M=7) occurred along this along occurred (M=7) earthquakes destructive 1693) the region. Major historically of (4 February 1169, activity 11 January seismic primary escarpment the for responsible Hyblean-Maltese is system the (2000), Barbano and et Azzaro and (1999) Scarfì al. et 2005; Bianca to al., According 2007). al., et (Musumeci area the in occurred respectively. motions, left-lateral and reverse been by have reactivated system, partially fault Scicli-Ragusa the of segments fault the as well as basins extensional Ragusa di Marina the and Scordia-Lentini the controlling faults normal the 0.85Ma, about since that demonstrated have 2008) 2006, al., et Catalano 2004; Lanzafame, and Recent (Bousquet studies 1988). Reuther, and Grasso 1980; Vezzani, and (Ghisetti system fault Scicli-Ragusa named system fault sedimentary deposits, are linked by a roughly N-S oriented al., 2000). Both tectonic depressions, filled with Quaternary et Grasso Ragusa Reuther,1988; and (Grasso south the di to Graben Marina the and north, the to Graben, Lentini Scordia- the Foredeep: Gela-Catania the along recognized al., 1997). (Yellin-Droret chain Appennine-Maghrebian the of front alignment, is downbent by a NE-SW fault system under the Catania Foredeep; Fig. Gela- 1B), that forming (named a roughly NE-SW belt extensional older an by characterized are Plateau Hyblean oceanic the of margins western and northern Mesozoic The 2000). al., et Ionian Adam 1993; al., et the Reuther (e.g., crust from inland crust thick the continental separates which basin, Mediterranean the of systems fault normal largest the of one 1B), (Fig. is bounded by the NNW-SSE Hyblean-Maltese escarpment 1999). Toal., plateau et the Doglioni east, 1990; the al., et process convergence Eurasia-Nubia (Barberi et al., 1973; Boccaletti and Manetti, the 1978; Patacca by deformed slightly foreland orogenic Tertiarythe of part is Sicily of BACKGROUND SETTING Plateau, convergence Eurasia-Nubia Hyblean could beadsorbedonthisarea. the of of part rim that northern suggesting the contractional along active process an evidencing in data and geophysical bothgeological with in agreement are findings Our established 1B). (Fig. network Plateau Hyblean the dense of rim northern the a along on 2009.78 and 1998.00 between collected data GPS continuous and episodic of aEurasian reference to frame) and strain-rate (referred field through field the velocity processing of terms in pattern ic 19 mr ta 40 atqae (>) have (M>1) earthquakes 450 than more 1994 Since be can basins NE-SW-oriented extensional main Two part south-eastern the in lying Plateau Hyblean The deformation ground horizontal the analyzed we Here, FIGURE 1 are asfollow:CT: Catania;RG:Ragusa; SI:Siracusa. Abbreviations (2005). al. et Musumeci from selected mechanisms cal events recorded between 1999 and 2007 (http://www.ct.ingv.it); 9) Fo- Seismic 8) faults; Main 7) fronts; thrust Main 6) sediments; carbonate Meso-Cenozoic 5) units; Appennine-Maghrebian 4) volcanics; blean Hy- Plio-Pleistocenic 3) volcanics; Etnean 2) Pleistocene-Holocene Late deposits; sedimentary Recent-Quaternary 1) Sicily. south-eastern of map sketch Structural B) (2003). Bird, from drawn are boundaries plate The Rift. African East the of west plate African the termed Nubia setting. tectonic plate Eurasia-Nubia the shows inset The Rift. Channel Sicily SCR: Ustica; US: follow: as are Abbreviations (2009). al. Mat- et tia from redrawn are <40km) depth (M≥3.5; earthquakes of nisms AN M I AGBH E R - NE NE PI A in observed be may seismicity nil by characterized Zones Graben,Rosolini-Pozzallo Scordia-Lentini and Scicli-Ragusa (e.g., fault systems; direction Fig. 1B). NNE-SSW and NE-SW overall an along striking faults inland secondary to due are (M<6) Weakershocks casualties. of thousands of tens causing 2000), Barbano, and (Azzaro system fault A 6 5 4 3 2 1 B N ( S (( ( 38°N (( 1 10

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Continuous GPS stations are models). equipped with Leica receivers (GRX1200 plane ground with Microcentered and Ring (Choke Trimbleantennas and models) 4700 and carried out adopting Trimble receivers (4000SSI, 4000SSE deformation of this area (Fig. 2, Table 1). GPS surveys were (23 benchmarks) with the aim of estimating the present day network the of part northern surveyedthe periodically has Nazionale di Geofisica e Vulcanologia – Sezione di Catania Instituto the 1998, Since area. Hyblean whole the of detail GPS 7 up set permanent stations (afterwards GPS) improving the spatial has Catania di Sezione – Vulcanologia e Geofisica di Nazionale Instituto the 2005, since project, (http://ring.gm.ingv.it) GPS di Nacionale Integrata Rete the of framework the In 2002). GPS al., install et (Bonforte directly antenna to order in top, the at screw a with pillars concrete and iron of consist monuments geodetic Distance Electro-optical new The 2). (Fig. benchmarks older GPS and technique Meters the including 50 stations, comprises currently and extended was network GPS the 1991, After (http://www.igmi.org). Italiano Militare Geografico Istituto the by installed route levelling a and 2001) in Catania e di Geofisica Sezione di – Vulcanologia Nazionale Instituto into Volcanologyof (merged Institute International the by 1991 Meters in installed EDM), Distance - technique Electro-optical by (surveyed network trilateration local a included partially network measured The 1991). al., et (Mulargia across Graben out Scordia-Lentini the carried was survey of GPS a region when plateau, easternmost the the M=5.4 struck the that after earthquake just 1990 1991, in started Plateau Hyblean GEODETIC NETWORK AND DATA PROCESSING faulting intheplateau(Musumecietal.,2005;Fig.1B). reverse and normal both of amounts lesser with solutions the Hyblean-Maltese Escarpment, and mainly by strike-slip along solutions fault-plane normal of predominance a by characterized are area focal study the Earthquake for inferred 2005). mechanisms al., et (Musumeci 25km to 15 extends to about 30km, with foci mainly concentrated from generally seismicity depth, In area. the of part central the TTIA et al. . l a t e A I T AT M . M ) 5 2 0 1 7 0 1 2 0 ( 0 0 8 0 - 0 1 . 5 , 0 ) 1 1 / ( 4 0 4 1 3 1 , . a 0 t 1 c A : I a O c D i g o l o e G All non-permanent and continuous GPS data, spanning the of deformations ground the of monitoring GPS FIGURE 2 s 1 CP sain; ) G sain (e ist o dtis; ) GPS 3) details); for inset benchmarks surveyed incampaignsmode. (see stations IGS 2) stations; CGPS 1) as: reported are work this in analyzed stations GPS frame. reference fixed epc t te egbuig ttos a b osre for observed be can stations neighbouring the to respect with variations However,some 1). (Table vector velocity campaign-continuous of this combination, both in magnitude and direction of the combined elements the among agreement good shows field and velocity The campaign site. nearby of permanent velocities the comparing by estimated be can stations permanent and campaign-mode surveyedsite in for solutions the consistencybetween The VELOCITY AND STRAIN-RATE FIELD 2007) andthenrotatedintoafixed Eurasiaframe. International daily al., 2005 et (Altamimi (ITRF2005) Frame TerrestrialReference the loosely-constrained into the transformed GLOBK were 2006b) of solutions al., module GLORG et the (Herring using By solution. network combined unconstrained daily a create to in order (http://sopac.ucsd.edu), Center Array Permanent and Orbit IGS3, Scripps the by provided solutions EURA) and IGS2, IGS4 usingthe (IGS1, global by with filter basis, Kalman adaily GLOBK on combined, are “h-files” individual the Next, matrices. covariance error associated and parameters orientation Earth positions, estimate site one-day of set a containing solutions loosely-constrained basic “h-files”, GAMIT are processing The data GPS the processing. of product the in included also were 2) Fig. LAMP,GRAZ, GRAS, MATE, NOT1NOTO;MEDI, and ( GRAS 3 2 1 AJAC ( ( CAGL The Eurasian velocity field frame is reported in Fig. 2. Fig. in reported is frame field velocity Eurasian The LAMP

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2 1 4 3 6 5 8 7 ARTICLE IN PRESS 9 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 ARTICLE IN PRESS 9 8 7 6 5 4 3 2 1 In general,thedurationofeachsurveyrangedbetween5and10days from 8 to 24 hours for each day of the surveys carried out during 2006. and 1998-2000 during out carried surveys the of day each for hours 8 to 6 from ranges window time occupation the benchmarks permanent account into in Fig. 5, in addition to the ones of the Hyblean Plateau. For non- taken are that stations GPS the all indicate points black the while networks, IGS or EUREF the to belong which sites GPS the cate indi- Asterisks benchmarks. all for errors associated with components TABLE 1 . l a t e A I T AT M . M aitos bevd o hs sain cud e u either due be could stations these to observed variations some stations like IP03, IP13, IMTR, IGAT and IP18). The ) 5 2 0 1 7 0 1 2 0 ( 0 0 8 0 - 0 1 . 5 , 0 ) 1 1 / ( 4 0 4 1 3 1 , . a 0 t 1 c A : I a O c D i g o l o e G IP06 IP04 IP03 MM01 MM01 IMTR MILO ● IM02 MATE * MATE IM01 LGUA * LAMP IGAT ISLI ICRC ISCP IRNE IPNC ZIMM * ICDR IAZZ IP21 VSER VSER HVZN IP19 IP18 HMDC HAVL IP16 USIX USIX HAGA IP14 TGRC ● TGRC GRAZ * GRAZ IP13 TIND ● TIND SSYX GRAS * GRAS IP12 RODI RODI RAFF IP10 NOTO * NOTO F EIIV IP09 NOT1 * NOT1 CORL CORL * CAGL Site IP07 MTTG MTTG LOR LOR ● ● ● ● ● ● ● ● ie oe goei codnts Es ad ot velocity North and East coordinates, geodetic code, Site Long. (deg) Long. 14.962 14.794 15.065 15.025 15.501 12.584 14.754 16.704 14.937 14.946 15.105 12.606 15.015 15.256 14.992 14.876 14.909 14.988 14.993 14.985 1 14.715 15.223 15.076 13.179 14.783 14.938 15.122 15.155 14.887 15.651 15.493 15.025 15.036 15.114 15.076 15.167 14.906 15.201 14.362 14.990 15.123 14.990 13.304 15.082 14.872 15.700 7.465 5.048 6.921 8.973 Lat. (deg) Table 01 Table 37.347 37.405 37.405 37.336 38.008 37.319 40.649 37.429 38.455 37.299 35.500 37.308 37.241 37.334 37.249 37.330 37.248 37.093 46.877 38.378 37.380 37.178 37.150 38.708 36.959 37.158 37.184 36.960 37.286 37.233 38.108 47.067 37.269 38.138 43.755 37.215 37.158 38.108 37.989 37.282 37.223 36.876 37.303 36.876 37.894 37.514 37.349 38.003 39.136 38.171 ------VE (mm/yr) 0.16 0.83 ± 0.57 0.84 ± 5.95 0.84 ± 3.55 0.82 ± 0.33 ± 0.68 0.33 ± 0.66 0.81 ± 1.15 ± 0.15 1.15 ± 1.69 0.79 ± 1.88 0.75 ± 1.80 1.70 ± 2.43 ± 1.10 0.96 ± 2.28 0.82 ± 0.23 ± 0.80 0.23 ± 1.11 0.80 ± 0.86 0.81 ± 0.59 0.82 ± 0.52 0.86 ± 0.71 ± 0.19 0.71 ± 1.01 0.72 ± 0.86 0.83 ± 3.67 0.81 ± 0.77 0.85 ± 0.24 ± 0.85 0.24 ± 0.34 0.81 ± 1.1 1.92 0.90 ± 0.59 0.94 ± 1.69 0.94 ± 0.16 0.97 ± 1.29 ± 0.57 1.29 ± 1.11 ± 0.15 1.11 ± 0.91 0.84 ± 1.56 0.69 ± 0 0.97 0.98 ± 0.76 0.80 ± 1.09 1.40 ± 2.93 1.11 ± 1.15 0.81 ± 1.58 0.92 ± 1.65 0.63 ± 1.7 1.1 0.12 0.94 ± 1.02 ± 0.25 1.02 ± 0.02 0.76 ± 2.41 ± 0.96 2.41 ± 0.75 ± 0.14 0.75 ± 0.66 ± 0.31 0.66 ± .56 ± 0.16 .56 ± 1 1 ± 0.80 1 ± 7 ± 0.19 7 ± ± 0.20 1.7 0 10.13 ± 0.79 ± 10.13 VN 5.31 ± 0.78 5.31 ± 1.90 ± 0.80 1.90 ± 6.88 ± 0.78 6.88 ± 3.58 ± 0.78 3.58 ± 2.40 ± 0.65 2.40 ± ± 0.77 4.51 ± 4.43 ± 0.10 4.43 ± 3.39 ± 0.76 3.39 ± 5.65 ± 0.71 5.65 ± 6.21 ± 1.55 6.21 ± 3.48 ± 0.13 3.48 ± 0.91 4.74 ± 5.02 ± 0.77 5.02 ± 5.73 ± 0 5.73 ± 6.52 ± 0.76 6.52 ± 5.79 ± 0.77 5.79 ± 0.77 6.50 ± 0.81 5.04 ± 0.77 ± 0.13 0.77 ± 0.69 9.44 ± 4.90 ± 0.78 4.90 ± 0.75 4.22 ± 5.65 ± 0.80 5.65 ± 1.81 ± 0.79 1.81 ± 4.95 ± 0.75 4.95 ± 7.1 6.22 ± 0.87 6.22 ± 4.95 ± 0.86 4.95 ± 0.86 4.82 ± 5.29 ± 0.93 5.29 ± 3.52 ± 0.54 3.52 ± 0.78 ± 0.10 0.78 ± 7.26 ± 0.66 7.26 ± 0.64 ± 0.12 0.64 ± 5.31 ± 0.93 5.31 ± 4.47 ± 0.75 4.47 ± 1.04 4.36 ± 2.08 ± 1.05 2.08 ± 4.56 ± 0.77 4.56 ± 5.12 ± 0.84 5.12 ± 0.59 3.83 ± 5.17 ± 0.76 5.17 ± 4.77 ± 0.12 4.77 ± 3.79 ± 0.86 3.79 ± 0.86 ± 0.17 0.86 ± 5.16 ± 0.74 5.16 ± 2.27 ± 0.87 2.27 ± 0.41 ± 0.09 0.41 ± 3.40 ± 0.22 3.40 ± 4 (mm/yr) ± 1.6 .76 2 ( are shown inFig.3. GPS stations of is dense. The distribution estimated horizontal strain-rates the where strain-rate detailed more a and to calculate a smoothed strain-rate in areas with few stations defined a curvilinear grid with variable knot-point spacing, we 1998), al., et (Haines method this Following spacing. variable of knots with grid curvilinear Bessel a on bi-cubic interpolation a using by geometry spherical a adopts which (1995), Holt Haines and and Holt by Haines improved and in (1993) proposed method the account into the foredeep. across observed ones the to than rather plateau the of part velocityvalue observedones the remaining to the close on a shows 2), (Fig.station RAFF the kilometersforedeep, the of fewnorth a located is it although north-westward, influenced by elastic strain accumulation on this fault. More couldmotion whose and faultsystem Scicli-Ragusa bethe to close installed is which station, HVZN the at observed is variation local a Furthermore, analyzed. are 2000 and 1998 in performed campaigns GPS the of results which in (2002), al. et values Bonforte to velocityaccording foredeep, the of across decrease a evidencing values (~2.0mm/yr) velocity lower with coupled variation azimuthal slight a show IM01) (EIIV,IP04, Foredeep Gela-Catania the to close located sites details, Eurasia- In convergence). the Nubia (i.e. structure tectonic long-term with large, according the ~5.0mm/yr of velocity average an motion northward with a by dominated is plateau the of part stations fromfurtheranalysis. these exclude to prefer observationswe these account into Taking2000). and 1998 in only measured were IP18 and observationlimited a (IGATto history or IMTR) and IP13 volcaniclastic and IP03, realized; was benchmark clays GPS the which in deposits of (outcrops instability site to cciRgs fut ytm te tanrt ae ae close are axes strain-rate the system, fault the Scicli-Ragusa along sparse are data Though ~0.1µstrain/yr. of rate direction to a NE-SW, with a maximum extensional strain- NNW-SSE a from rotation clear a shows axis west the east, from to where, itself plateau the of sector central the in domain extensional an to transition slow a is there and strength its looses partially shortening the south, the To foredeep. the of limit NNW-SSE,the to along plateau, the of border coastal north-eastern the along N-S, from varies 3A) (Fig. direction rate strain ~0.2µstrain/yr. shortening maximum of The strain-rate negative maximum a plateau with the of rim northern the along area contractional a defines clearly pattern The strain-rate. dilatation the of magnitude the show background the in contours the while ἐ Hma n i. A te ros hw h gets extensional greatest the show arrows the 3A, Fig. In taking computed was field strain-rate horizontal The the north-eastern that indicates field velocity The ad otatoa ( contractional and ) Ground deformationoftheHybleanplateau(Sicily, Italy) ἐ hmax hrzna strain-rates, horizontal ) 4 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 ARTICLE IN PRESS 9 8 7 6 5 4 3 2 1 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 ARTICLE IN PRESS 9 8 7 6 5 4 3 2 1 TTIA et al. . l a t e A I T AT M . M ) 5 2 0 1 7 0 1 2 0 ( 0 0 8 0 - 0 1 . 5 , 0 ) 1 1 / ( 4 0 4 1 3 1 , . a 0 t 1 c A : I a O c D i g o l o e G ae en netgtd hog nnpraet and non-permanent through investigated been have DISCUSSION observed (Fig.3B). easily be can directions shear maximum conjugate the and computed for the investigated area (Musumeci et al., 2005) planes focal of azimuths the between agreement striking discrete a fault, Scicli-Ragusa the Along of seismicity. sector northern strong the of areas the with overlapping the along partially faultsystem, Scicli-Ragusa the of sector and northern Graben Scordia-Lentini the are on strain-rates observed shear maximum Higher 3B). (Fig. lines cross- as directions these reported we structures, those on shear to related is faults along motion since faults, active providemight directions shear maximum identify to tool a conjugate) (two the Because background. the in contour a Lentini Graben). Scordia- the (i.e. regionnarrow really a in accommodated is deformation the of part large a pattern as evidencing 3A), general (Fig. strain-rate dilatation This the 2008). by confirmed al., is et pattern (Catalano expected as slip strike left-lateral for oriented and zone fault the to 45° to FIGURE 3 mechanisms arealso reported. shear strain-rate, computed as maximum the of magnitude the show background the in contours the B) strain-rates, horizontal (blue) contractional and (red) extensional greatest the

( 0 -0.25

10 0 ( Velocity and strain-rate fields of the Hyblean Plateau Hyblean the of fields strain-rate and Velocity The maximum shear strain-rate is reported in Fig. 3B as ( 0.2 mstrain/yr lengthening mstrain/yr

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kilometers ( ( (

Geodetic strain-rate parameters: A) the contours in the background show the magnitude of the dilatation strain-rate while arrows represent arrows while strain-rate dilatation the of magnitude the show background the in contours the A) parameters: strain-rate Geodetic ( ( ( ( 0.10 ( 20 ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( (

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( 0.00 eciae b rvre oin uig h ls 0.85Myr last the during motion reverse by reactivated been have Graben Scordia-Lentini normal the controlling that faults showed have data geological particular, In and Bousquet 2002; al., 2001). al., et Froger Borgia1992; Lanzafame,2004; al., et et (Monaco Etna Mt. southern of lower slope the to Graben Scordia-Lentini the from foredeep the across 25km about extending area an along shortening active detected data (InSAR) Radar Aperture N-S- Synthetic Interferometric axesand geological Recent oriented. contractional prevailing with plateau, the of rim northern a the along (~0.2µstrain/yr) across evidenced area contractional strain-rate Resulting localized 4). (Fig. foredeep shortening the evidencing (~2.0mm/yr) values velocity low show system, fault Scicli-Ragusa the the Gela-Catania Foredeep (EIIV, IP04, IM01), eastward of (i.e. the Eurasia-Nubia convergence). Sites located close to about 5.4mm/yr according of to a dominated large, velocity long-term tectonic structure average is an plateau with motion the northward of by part large a that indicates pattern deformation the acting onlyalongthenorth-easternpartofplateau. to us about allows knowledge dataset the geodetic improve this so sparse, are itself plateau the within data while plateau, the of sector eastern north- the in good is coverage network The 2009.78. and 1998.00 between collected measurements GPS permanent 10 0 ( ( ( mstrain/yr kilometers ( ( frame Eurasian stable a to referred field velocity The ( ( (

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10 12 11 14 13 16 15 18 17 20 19 22 21 24 23 26 25 28 27 30 29 32 31 34 33 36 35 38 37 40 39 42 41 44 43 46 45 48 47 50 49 52 51 54 53 55

2 1 4 3 6 5 8 7 ARTICLE IN PRESS 9 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 ARTICLE IN PRESS 9 8 7 6 5 4 3 2 1 eastern sector of the foredeep to the north of Sicily across a eastern sectoroftheforedeep. the across process contractional the transfer accommodating fault left-lateral a of role the play Scicli-Ragusa could system the fault picture, deformation this is in process inactive; contractional the whereas segment Foredeep; western the Gela-Catania along the of sector eastern foredeep, thefollowing considerationscanbedone: the across observed ones the to than rather plateau the of velocity value close to the ones observed on the remain part and a shows foredeep, the of north kilometers few a located is (D’Agostino Sicily of Selvaggi, north 2004). Considering that the RAFF station, which the estimated to one the (~4.0mm/yr) to close very but therein) references and 2007 al., et Doglioni (~1.0mm/yr; Sicily mainland for estimations geodetic previous with compared if high very is value This convergence. Eurasia-Africa the to parallel direction a along 4.4mm/yr about at estimated be can rate total convergence the 4, in Fig. reported profile velocity GPS the Considering process. compressive active still a Gela-Catania Foredeep with fine resolution and evidencing bothgeological with and InSAR data, mapping the contractional area across the agreement in good is finding 2004). Our Lanzafame, and Bousquet 2002; al., et (Monaco chain the of front compressive active the to related age) Pleistocene (Lower-Middle features syn-sedimetary has sediments, pre-Etnean deforming structure, compressional this that demonstrated have data Geological 2001). al., et Froger 1992; al., et (Borgia Plain Catania the and volcano the of slope southern lower the between 30km about for E-W-orientedanticline large a extendingof satellite the of have Etna, Mt. at detected an active patterns uplift of the ground along deformation the line of sight ground recent mapping data, InSAR addition, In 2008). al., et (Catalano . l a t e A I T AT M . M ) 5 2 0 1 7 0 1 2 0 ( 0 0 8 0 - 0 1 . 5 , 0 ) 1 1 / ( 4 0 4 1 3 1 , . a 0 t 1 c A : I a O c D i g o l o e G FIGURE 4 faults. ME: Mount Etna; CP: Catania Plain; CGF: Catania-Gela Foredeep. sedimentary deposits; 4) Meso-Cenozoic carbonate sediments; 5) Main Recent-Quaternary 3) units; Appennine-Maghrebian 2) volcanics; nean Et- Pleistocene-Holocene Late 1) direction. same the along distance Velocity (mm/yr) 4 6 8 0 2 0 i Te otatoa poes s rnfre fo the from transferred is process contractional The ii) the along only active is process contractional The i) ME EIIV Horizontal velocity in the N20°W direction as a function of function a as direction N20°W the in velocity Horizontal 10 CP IM01 IP04 CGF 20 itneaogpoie(km) profile along Distance IP10 30 yla Plateau Hyblean 40 IP21 50 1 2 60 3 4 NOTO 70 5

2 4 6 0 lvto (km) Elevation pta cvrg o GS ttos n h etr Hyblean entire Plateau couldbetteraddressthisproblem. the on stations GPS of coverage spatial the in improvements and discussed being still are picture (2008). tectonic al. Anyway,this et of Catalano details the by supposed already as foredeep the of sector eastern the left-lateral a on process contractional the accommodating as fault transfer work could system fault Scicli-Ragusa the that indicate data, geological and seismological with coupled they, however stations, few very with are estimated values these that aware left-lateral are We for respectively. (positive shear), 1mm/yr ca. and 3mm/yr ca. of component strike-slip a and fault tensile a N10°E estimated we trend, mean a Using Foredeep. Gela-Catania the of north located is it because analysis this from excluded (located on the right side of the system). RAFF station was stations IM02 and HMDC and system) fault the of left the by taking into account velocity values at HVZN (located on movementopening) or tensile (i.e. strike- perpendicular and slip) (i.e. parallel of In rates the fault. estimated the we across particular, located stations of velocities the of Scicli- the of Ragusa fault system, we applied a vectorial kinematic decomposition the al., estimate to et order Musumeci In 2005). area; the striking earthquakes strong and for computed 2008) mechanisms al., focal (i.e. et data seismological (Catalano data geological with both agreement In in slip strike left-lateral for oriented system. and zone fault the fault strong to 45° to close are of Scicli-Ragusa axes strain-rate the addition, occurrence the of along areas seismicity the partially with of (~0.16µstrain/yr), overlapping values strain-rate high shear by maximum characterized is Foredeep Catania transfer zoneactive incentralSicily(Fig.5). FIGURE 5 USIX CORL).SeeTable 1fordetails. VSER, FLOR, (LGUA, RODI, MM01, TIND, 2009) TGRC, MTTG) and and iii) unpublished (2008 data (MILO, al. et Mattia ii) SSYX); HAVL, NOTO, to a fixed Eurasian frame are from i) this work (EIIV, IP04, RAFF, HMDC, MILO About the first point, the eastern sector of theGela- of sector eastern the point, first the About 0km 50

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( ( RAFF IP04 ? HMDC FLOR TIND NOTO EIIV LGUA VSER HAVL SSYX RODI MM01 TGRC MTTG 6 N S 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 ARTICLE IN PRESS 9 8 7 6 5 4 3 2 1 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 ARTICLE IN PRESS 9 8 7 6 5 4 3 2 1 TTIA et al. . l a t e A I T AT M . M referee for their reviews and comments that led to substantially to led that comments and reviews their for referee ) 5 2 0 1 7 0 1 2 0 ( 0 0 8 0 - 0 1 . 5 , 0 ) 1 1 / ( 4 0 4 1 3 1 , . a 0 t 1 c A : I a O c D i g o l o e G ACKNOWLEDGMENTS area. the on studies process deformation improve better should projects important other and GPS di NacionaleIntegrata of coverage GPSstations spatial thewholeonSicilyof planned as theRete by the in improvements and discussed transfer zone. active an geological of presence the neither for evidences seismological nor currently are there However, Sicily. regional a of tothe north ofSicily across transfera zone active transferincentral a conjecture contractional toprocess from the eastern sector us of the foredeep allow data, sector of the foredeep. agreement in fault transferaccommodating contractional left-lateralthe processeastern alongthe are a as findings movement possible a our with system, fault Ragusa area. data, evidencing a still active InSARconvergence and geological bothprocess withalong agreement this good in rate) strain-rateof~0.2µstrain/yr (i.e. ~4.4mm/yr ofconvergence negativemaximum a with plateau the of rim northern the motion velocity averaged northward according to the 5.4mm/yr Eurasia-Nubia convergence process. a by indicate that a large part of the Hyblean Plateau is dominated previous section, we may draw the following conclusions: CONCLUSION address the problem here conjectured. networkGPS covering Sicilywholetheofcould also better centralSicily. Again,theimprovement denserofa in active transfer zoneandlarger an presence of evidences the about seismological geological nor neither are there details), for references therein and (2009), al. et Mattiapublished; see previously data large-scale GPS (seismological andSicily ofthe Gela-Catania Foredeep (this study) and along northern contractionalareaslocated respectively easterntheon sector e hn Po. eú Glno advr n a anonymous an and Zaldívar Galindo Jesús Prof. thank We being still are picture tectonic this of details Main published previously with coupled findings These iv) Scicli- the along sparse are data geodetic Though iii) alongcontractional strain-rateareaevidenced a The ii) frame Eurasian stable a to referred fields Velocityi) the indiscussed and herepresented data the on Based About the second point, despite the presence of two active Catalano, S., De Guidi, G., Lanzafame, G., Monaco, C., Torrisi,C., Monaco, G., Lanzafame, G., Guidi, De S., Catalano, and Compression 2004. G., Lanzafame, J.C., Bousquet, of Importance 1992. G., Pasquarè, L., Ferrari, A., Borgia, Campisi, M., Mattia, G., Puglisi, M., Anzidei, A., Bonforte, and sea Tyrrhenian The 1978. P., Manetti, M., Boccaletti, boundaries. plate of model digital updated An 2003. P., Bird, 1999. L., Cernobori, L., Tortorici, C., Monaco, M., Bianca, 1973. L., Villari, F., Innocenti, P., Gasparini, F., Barberi, seismicity the of Analysis 2000. M.S., Barbano, R., Azzaro, Altamimi, Z., Collilieux, X., Legrand, J., Garayt, B., Boucher, C., Active 2000. L., Torelli, C.M., Reuther, M., Grasso, J., Adam, REFERENCES Mario and English ofthepaper. Pellegrino Daniele Pulvirenti. We thank S. 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Ground deformationoftheHybleanplateau(Sicily, Italy) 7

10 12 11 14 13 16 15 18 17 20 19 22 21 24 23 26 25 28 27 30 29 32 31 34 33 36 35 38 37 40 39 42 41 44 43 46 45 48 47 50 49 52 51 54 53 55

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