Seismotectonic zoning in east-central Italy deduced from an analysis of the Neogene to present deformations and related stress fields

Abstract

Research Article| September 01, 1994 Seismotectonic zoning in east-central Italy deduced from an analysis of the Neogene to present deformations and related stress fields GIUSY LAVECCHIA; GIUSY LAVECCHIA 1Dipartimento di Scienze della Terra, Piazza Universitaà 06100 Perugia, Italy Search for other works by this author on: GSW Google Scholar FRANCESCO BROZZETTI; FRANCESCO BROZZETTI 1Dipartimento di Scienze della Terra, Piazza Universitaà 06100 Perugia, Italy Search for other works by this author on: GSW Google Scholar MASSIMILIANO BARCHI; MASSIMILIANO BARCHI 1Dipartimento di Scienze della Terra, Piazza Universitaà 06100 Perugia, Italy Search for other works by this author on: GSW Google Scholar MARCO MENICHETTI; MARCO MENICHETTI 1Dipartimento di Scienze della Terra, Piazza Universitaà 06100 Perugia, Italy Search for other works by this author on: GSW Google Scholar JOAO V. A. KELLER JOAO V. A. KELLER 2Royal Holloway and Bedford New College, Geology Department, Egham, England Search for other works by this author on: GSW Google Scholar GSA Bulletin (1994) 106 (9): 1107–1120. https://doi.org/10.1130/0016-7606(1994)106<1107:SZIECI>2.3.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation GIUSY LAVECCHIA, FRANCESCO BROZZETTI, MASSIMILIANO BARCHI, MARCO MENICHETTI, JOAO V. A. KELLER; Seismotectonic zoning in east-central Italy deduced from an analysis of the Neogene to present deformations and related stress fields. GSA Bulletin 1994;; 106 (9): 1107–1120. doi: https://doi.org/10.1130/0016-7606(1994)106<1107:SZIECI>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract This paper concerns the space-time evolution of the late Miocene to present contractional and extensional deformations within east-central Italy, with an analysis of the pattern and orientation of the related stress field, an insight into the cover-basement relations, and a discussion of the seismotectonic implications.The pattern and orientation of the deformation and stress fields have remained unchanged since late Miocene time and have been always characterized by the coexistence and parallelism in contiguous areas in a given time of shortening to the east and elongation to the west. With time, during a multistage deformation history, both the contraction and the extension fields have moved eastward. Basement-involved tectonics with a west-dipping multiple detachment system would have allowed the progressive eastward shift of crustal slices, corresponding at the surface to well-defined tectonic domains, with consequent crustal thinning in the Tuscan zone and crustal thickening beneath the Apennine mountain chain.By comparing macroseismic epicenters, hypocenters, and focal mechanisms with crustal structure and independently known active faults, it appears evident that the pattern, frequency, and distribution of the crustal seismicity are tectonically controlled and that a contraction-extension pair is active also at the present time. In fact, along the Adriatic coastline, contractional deformation prevails with involvement of Pleistocene layers, whereas beneath the Apennine Range, extensional deformation prevails. Both T-axes in the inner domain and P-axes in the outer domain are oriented southwest-northeast or west-south-west east-northeast, and this coaxiality reflects the situation depicted by the geologic stress field. On this basis, we have produced a seismotectonic zoning of east-central Italy with three distinct domains: Intramountain Seismic Zone (ISZ), Foothills Seismic Zone (FSZ), and Coastal Seismic Zone (CSZ).A plausible explanation for the genesis of the "active" seismic deformations of east-central Italy is that the locally intense extensional upper-crustal seismicity of the Intramountain Seismic Zone is confined to the hanging wall of a major, west-dipping, active extensional discontinuity, whereas the less frequent contractional seismic activity of the Coastal Seismic Zone is within the hanging wall of an outer major, active, west-dipping contractional discontinuity. An area of overlap between these two zones is represented by the Foothills Seismic Zone, where superposed epicentral patterns from different surfaces of weakness at different depths are the predictable result of the asymmetry of the deformation. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.