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Pierri, Pierpaolo
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Pierri, Pierpaolo
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- PublicationOpen AccessLithosphere-asthenosphere system in shield areas of North America and Europe(1997-10)
; ; ; ;Calcagnile, G.; Dipartimento di Geologia e Geofisica, Università di Bari, Italy ;Del Gaudio, V.; Dipartimento di Geologia e Geofisica, Università di Bari, Italy ;Pierri, P.; Osservatorio di Geofisica e Fisica Cosmica, Università di Bari, Italy; ; In previous papers surface dispersion data have been combined with the results of deep seismic refraction data to derive a regionalization of the lithosphere-asthenosphere system and to investigate the presence of significant heterogeneity down to depths of 350 km along two profiles in the North European Fennoscandian area; a regionalized upper mantle model for the whole area down to more than 400 km is given as cross sections. We have extended that approach to North America. The older part of the shield shows lid thickness up to more than 100 km with, if any, weak shear velocity contrast to the underlying layer. The surrounding areas are characterized by a thinner lid; a stronger low-velocity zone to lid contrast may be found in peripheral areas. A map of the lithosphere-asthenosphere system has been derived, permitting a better regional resolution of the shear-wave velocity distribution with depth beneath different regions of North America. The correlation between the lithosphere-asthenosphere system structure and other geophysical data is commented as well as the results for North America and those obtained for the corresponding North European area, in order to outline the geophysical characteristics of shield areas that might give useful constraints for the geodynamic behaviour of the plates to which they belong.160 380 - PublicationOpen AccessEvidence of Apulian crustal structures related to low energy seismicity (Murge - Southern Italy)(2001-10)
; ; ; ; ; ; ; ; ; ;Del Gaudio, V.; Dipartimento di Geologia e Geofisica, Università di Bari, Italy ;Festa, V.; Dipartimento Geomineralogico, Università di Bari, Italy ;Ripa, R. R.; Dipartimento di Geologia e Geofisica, Università di Bari, Italy ;Iurilli, V.; Dipartimento di Geologia e Geofisica, Università di Bari, Italy ;Pierri, P.; Osservatorio Sismologico, Università di Bari, Italy ;Calcagnile, G.; Dipartimento di Geologia e Geofisica, Università di Bari, Italy ;Moretti, M.; Dipartimento di Geologia e Geofisica, Università di Bari, Italy ;Pieri, P.; Dipartimento di Geologia e Geofisica, Università di Bari, Italy ;Tropeano, M.; Dipartimento di Scienze Geologiche, Università della Basilicata, Potenza, Italy; ; ; ; ; ; ; ; The discovery of recent co-seismic sedimentary structures and the detection of low energy seismic activity in the Murgian plateau (Apulia - Southern Italy) motivated a more detailed examination of the tectonics in this part of the Apulian plate commonly believed to be aseismic. In particular, we examined the north-western zone where a seismic sequence with maximum magnitude 3.2 and tensional focal mechanism occurred in 1991. The analysis of the existing gravimetric data, integrated by three new profiles carried out across the epicentral area, disclosed an anomaly possibly due to an old tensional tectonic structure located within the upper crust. Even though the depth and the age hypothesised for the anomaly source would exclude a direct causal connection with the observed seismicity, this structure could be a shallower expression of a tectonic structure extending down to the crystalline basement: it could represent a zone of relative «weakness» where the regional stress, due to the interactions between Apennines and Apulian plate, encounters conditions facilitating the release of seismic energy.175 369 - PublicationOpen AccessSeismogenic Structure Orientation and Stress Field of the Gargano Promontory (Southern Italy) From Microseismicity Analysis(2021-04)
; ; ; ; ; ; ; ; ; ; ; Historical seismic catalogs report that the Gargano Promontory (southern Italy) was affected in the past by earthquakes with medium to high estimated magnitude. From the instrumental seismicity, it can be identified that the most energetic Apulian sequence occurred in 1995 with a main shock of MW = 5.2 followed by about 200 aftershocks with a maximum magnitude of 3.7. The most energetic earthquakes of the past are attributed to right-lateral strike-slip faults, while there is evidence that the present-day seismicity occur on thrust or thrust-strike faults. In this article, we show a detailed study on focal mechanisms and stress field obtained by micro-seismicity recorded from April 2013 until the present time in the Gargano Promontory and surrounding regions. Seismic waveforms are collected from the OTRIONS Seismic Network (OSN), from the Italian National Seismic Network (RSN), and integrated with data from the Italian National Accelerometric Network (RAN) in order to provide a robust dataset of earthquake localizations and focal mechanisms. The effect of uncertainties of the velocity model on fault plane solutions (FPS) has been also evaluated indicating the robustness of the results. The computed stress field indicates a deep compressive faulting with maximum horizontal compressive stress, SHmax, trending NW-SE. The seismicity pattern analysis indicates that the whole crust is seismically involved up to a depth of 40 km and indicates the presence of a low-angle seismogenic surface trending SW-NE and dipping SE-NW, similar to the Gargano–Dubrovnik lineament. Shallower events, along the eastern sector of the Mattinata Fault (MF), are W-E dextral strike-slip fault. Therefore, we hypothesized that the seismicity is locally facilitated by preexisting multidirectional fractures, confirmed by the heterogeneity of focal mechanisms, and explained by the different reactivation processes in opposite directions over the time, involving the Mattinata shear zone.59 63 - PublicationRestrictedA critical revision of the seismicity of Northern Apulia (Adriatic microplate - Southern Italy) and implications for the identification of seismogenic structures(2007-03-03)
; ; ; ; ; ; ;Del Gaudio, V.; Dipartimento di Geologia e Geofisica, University of Bari ;Pierri, P.; Dipartimento di Geologia e Geofisica, University of Bari ;Frepoli, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Calcagnile, G.; Dipartimento di Geologia e Geofisica, University of Bari ;Venisti, N.; Dipartimento di Geologia e Geofisica, University of Bari ;Cimini, G. B.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; ; ; ; ; Northern Apulia is an emerged portion of the Adriatic microplate, representing the foreland–foredeep area of a stretch of the Apennine chain in southern Italy. The interaction between the relatively rigid microplate and the contiguous more deformable domains is responsible for the intense seismicity affecting the chain area. However strong, sometimes even disastrous, earthquakes have also hit northern Apulia on several occasions. The identification of the causative faults of such events is still unclear and different hypotheses have been reported in literature. In order to provide guidelines and constraints in the search for these structures, a comprehensive re-examination and reprocessing of all the available seismic data has been carried out taking into consideration 1) the characteristics of historical events, 2) the accurate relocation of events instrumentally recorded in the last 20 years, 3) the determination of focal mechanisms and of the regional stress tensor. The results obtained bring to light a distinction between the foreland and foredeep areas. In the first region there is evidence of a regional stress combining NWcompression and NE extension, thus structures responsible for major earthquakes should be searched for among strike–slip faults, possibly with a slight transpressive character. These structures could be either approximately N–S oriented sinistral or E–Wdextral faults. In the foredeep region there is a transition toward transtensive mechanisms,with strikes similar to those of the previous zone, or maybe also towardsNWoriented normal faults,more similar to those prevailing in the southern Apennine chain in relation to a dominant NE extension; this appears to be the effect of a reduction of the NW compression, probably due to a decrease in efficiency of stress transmission along the more tectonised border of the Adriatic microplate.225 28