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CNR IRPI, Perugia, Italy
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- PublicationRestrictedAnalysis of the 9 September 1998 Mw 5.6 Mercure earthquake sequence (Southern Apennines, Italy): A multidisciplinary approach(2009)
; ; ; ; ; ;Brozzetti, F.; Geodynamics and Seismogenesis Laboratory, Dipartimento di Scienze della Terra, Università “ G. d'Annunzio” - Chieti, Italy ;Lavecchia, G.; Geodynamics and Seismogenesis Laboratory, Dipartimento di Scienze della Terra, Università “ G. d'Annunzio” - Chieti, Italy ;Mancini, G.; Geodynamics and Seismogenesis Laboratory, Dipartimento di Scienze della Terra, Università “ G. d'Annunzio” - Chieti, Italy ;Milana, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Cardinali, M.; CNR IRPI, Perugia, Italy; ; ; ; The Mercure earthquake (Mw 5.6) of September 9, 1998 and the associated aftershocks occurred in a small Pleistocene–Holocene continental basin of the Southern Apennines, in a region of low instrumental and moderate historical seismicity. Seismological, photogeological and field survey data were analyzed and integrated in order to identify the likely seismogenic structure, to depict its 3-D geometry and kinematics and to provide further constraints to the seismogenic potential of the rupture processes in the study area. The mainshock occurred at the NW edge of the seismic sequence (40.03°N and 15.95°) at a depth of 10.5± 1.5 km. The aftershocks volume was determined from the relocation of about 200 events (1.1=Ml=3.9) registered by local networks from September 10 to October 12, 1998. The relocation procedure was based on choosing P and S waves for all the events and the definition of ten 9-layers velocity models appropriate for the different stations. The kinematics of the seismogenic deformation was defined through the computation of 36 well-constrained focal mechanisms. The seismological and geological stress tensors were determined through inversion of focal mechanisms and fault slip data. Both of them resulted in the tensional type, with ENE–WSW and NE–SW trending σ3 axis, respectively. The map and the section distribution of the aftershocks sequence depicts an average NW–SE striking and 60° SW-dipping seismogenic volume. Most of the events (80%) were located at depths between 3 and 8 km in the footwall of the Mercure basin (MBB) boundary fault but along the possible down-dip continuation of a previously unidentified, N120°E striking and WSW-dipping, Holocene normal fault alignment, which extends from Castello Seluci to Piana Perretti and Timpa della Manca (CPST fault). A small percentage of events (10%) were located at depths between 10 and 12 km where the CPST seismogenic fault may detach. The reconstructed rupture area (RA) of the Mercure 1998 earthquake has an along-strike length (L) of about 9 km and a down-dip width (W) of about 9 km, yielding a total area of approximately 81 km2 . On the other hand, the L and W dimension of the entire individual seismogenic structure identified as responsible for the earthquake, e.g. the CPST fault, are about 19 and 12 km, respectively, with a consequent RA of about 230 km2 . This may imply a maximum magnitude (Mw) equal to 6.3 which lead us to compare the Mercure area, in terms of seismogenic hazard, to the adjacent Pollino-Castrovillari area where strong paleoseismological events are documented.185 38 - PublicationOpen AccessQualitative and quantitative photogrammetric techniques for multi-temporal landslide analysis(2006-08)
; ; ; ; ; ;Zanutta, A.; Dipartimento di Ingegneria delle Strutture, dei Trasporti, delle Acque, del Rilevamento, del Territorio (DISTART), Università degli Studi di Bologna, Italy ;Baldi, P.; Dipartimento di Fisica, Università di Studi di Bologna, Italy ;Bitelli, G.; Dipartimento di Ingegneria delle Strutture, dei Trasporti, delle Acque, del Rilevamento, del Territorio (DISTART), Università degli Studi di Bologna, Italy ;Cardinali, M.; Istituto di Elettronica e di Ingegneria dell’Informazione e delle Telecomunicazioni (IEIIT), CNR, Bologna, Italy ;V, A.; Istituto di Ricerca per la Protezione Idrogeologica (IRPI), CNR, Perugia, Italy; ; ; ; The results of two survey methods, geological photointerpretation and historical photogrammetry, are compared in order to evaluate the temporal evolution of a unstable slope located in the Tuscan-Emilian Apennines (Italy). Historical aerial photos of the area, derived from photogrammetric surveys conducted in 1954 (scale 1:60000), in 1971 (scale 1:20000), and in 1976 (scale 1:17000) were available. A photogrammetric flight was further conducted in 2000, at a scale of 1:4400, with a traditional GPS ground survey support. First, the results of photographic analysis with the photointerpretation method are presented: the landslides are described from a geological point of view, showing its temporal evolution. To quantitatively assess the landslide movements, Digital Terrain Models were generated by means of an analytical plotter and a digital photogrammetric workstation, with semi-automatic and automatic procedures. To generate these products, it was necessary to solve problems related to a lack of data concerning the aerial cameras used for the historical flights (internal orientation) and the difficulty identifying control points on the photos in order to define the external orientation. An unconventional photogrammetric methodology, based on identification of homologous points in zones considered outside the landslide area, has been there developed and tested to insert the various surveys into a single reference system.310 1154