GEOD 503 Disk used No. pages 21, DTD=4.3.1 Version 7.51e ARTICLE IN PRESS UNCORRECTED PROOF Active tectonics of the Northern Apennines and Adria geodynamics: new data and a discussion Daniela Di Bucci a, *, Stefano Mazzoli b a National Seismic Survey, Via Curtatone n. 3, 00185 Rome, Italy b Facolta ` di Scienze Ambientali, Universita ` di Urbino, Campus Scientifico Sogesta, 61029 Urbino (PU), Italy Received 2 November 2001; received in revised form 30 June 2002; accepted 5 August 2002 Abstract TheactivegeodynamicsettingoftheNorthernApenninesischaracterisedbyextensionintheaxialzone ofthechain,andbyamorecomplextectonicbehaviourinthefrontalpartofthebelt.Inthelattersector, moderateseismicityoccurs,displayingcompressional,strike-slipandextensionalfocalplanesolutionswith variably oriented P and T axes. For this area, a review of available geological and geophysical data has beenintegratedbytheanalysisofseismicreflectionlinescalibratedwithdeepwelllogs.Thisstudyconfirms that,asalreadysuggestedbysomepreviousworkers,thrustingandrelatedfoldinginthestudyareaceased in Early Pleistocene times. This feature is in contrast with the hypothesis of active thrusting related to a subducting lithospheric slab beneath the chain—an issue which is largely debated based on available geo- physical information. Our analysis shows that the Northern Apennines are characterised by an active tec- tonicsettingwhichissimilartothatofthecentralandsouthernportionsofthebelt.Theseareasalldisplay aLateQuaternaryinactivityofthethrustfront.NE–SWorientedextension(perpendiculartothestrikeof the orogen) is well established in their axial zones, whereas a less homogeneous stress field characterises their external sectors and the adjacent foreland. Within this framework, the seismotectonic behaviour of the Northern Apennines—and probably of the whole Italian peninsula between the Po Plain and the Southern Apennines (north of the Calabrian Arc)—may be interpreted as essentially controlled by two main processes. The first of them involves tectonic uplift, possibly related with slab detachment and asso- ciated unbending of the foreland plate. The second process consists of a present-day northwestward motion of the Adria block with respect to stable Europe. # 2002 Published by Elsevier Science Ltd. 0264-3707/02/$ - see front matter # 2002 Published by Elsevier Science Ltd. PII: S0264-3707(02)00107-2 Journal of Geodynamics & (&&&&) &–& www.elsevier.com/locate/jog 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 * Corresponding author. Tel.: +39-06-444-42761; fax: +39-06-446-6579. E-mail address: daniela.dibucci@serviziosismico.it (D. Di Bucci).