Description: This article has been accepted for publication in Geophysical Journal Internationa ©: 2017 Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

Description: We present a 2-D subsurface image of the Paganica Fault from a high-resolution refraction tomography and detailed geological investigation carried out across part of the northwestern segment of the 20-km-long Paganica–San Demetrio fault-system, and which was responsible of the 2009 April 6 Mw 6.1 L’Aquila earthquake (central Italy). We acquired two seismic profiles crossing the Paganica basin with a dense-wide aperture configuration. More than 30 000 P wave first-arrival traveltimes were input to a non-linear tomographic inversion. The obtained 250–300 m deep 2-D Vp images illuminate the shallow portion of the Paganica Fault, and depict additional unreported splays defining a complex half-graben structure. We interpret local thickening of low-Vp (〈2400 m s−1) and intermediate-Vp (2600–3400 m s−1) regions as syn-tectonic clasticwedges above a high-Vp (3800–5000ms−1) carbonate basement. These results are condensed in a 4.2-km-long section across the Paganica basin, clearly indicating that the Paganica Fault is a mature normal fault cutting the whole upper ∼10 km of the crust. We evaluate a minimum cumulative net displacement of 650 ± 90 m and a total heave of 530 ± 65 m accomplished by the Paganica Fault, respectively. In the conservative hypothesis that the extension started during the Gelasian (1.80–2.59 Ma),we obtain a minimum long-term slip-rate of 0.30 ± 0.07 mm yr−1 and an extension-rate of 0.25 ± 0.06 mm yr−1, respectively. Considering the regional averaged extensional field of ∼1 mm yr−1 obtained from geodetic and geological analyses at 104 yr timescale, we infer that the Paganica Fault accounts for ∼20 per cent of the NE-extension affecting this zone of the central Apennines axis due to the concurrent activity of other parallel normal fault-systems nearby (e.g. the Liri, Velino-Magnola, L’Aquila-Celano and Gran Sasso fault-systems).

Description: Published

Description: 403-423

Description: 1T. Deformazione crostale attiva

Description: JCR Journal

Description: We present the results of a combined analysis of remote sensing and geophysical ‐ geotechnical data carried out in the Acque Albule Basin, a sinkhole prone area located close to the city of Roma, where a wide travertine wedge is present. We carried out geophysical measurements and borehole drillings over two test areas to image the subsoil where paroxysmal sur fi cial dynamics occur. One site is marked by subsidence occurring at least since the early 2000s, whereas the other site hosts the “ La Regina ” and “ Colonnelle ” sinkhole lakes, which discharge sulfur ‐ carbonated waters. The stability of these two sites threatens highway, railway, and airport facilities, and this study helps to assess the geological hazard. For example, InSAR and LiDAR data helped de fi ne wide scale subsidence over the last 20 years and previously undetected small ‐ scale morphologies. Geophysical measurements of the latter revealed shallow and deep dissolution affecting the travertine and driving sur fi cial paroxysmal events. Both study sites were found to lie inside a large depression located at the junction between Jurassic carbonate and Plio ‐ Pleistocene units in association with paleo karst morphologies in the travertine deposits and affected by the present ‐ past spillage of sulfurous waters. Given these elements, multidisciplinary geophysical observations are crucial for assessing and mitigating the geological risk and guiding land use planning and management.

Description: Published

Description: e2019EA000870

Description: 6T. Studi di pericolosità sismica e da maremoto

Description: JCR Journal

Description: In case of moderate to strong earthquakes (generally for M 〉 5.5), coseismic slip along a fault can reach directly the ground surface and produce surface faulting. Although scarcely considered in the Italian legislation, surface faulting hazard can have a relevant societal impact because it exposes to substantial risk urban areas and/or important infrastructures, facilities and critical lifelines that are settled or planned in coincidence of an active and capable fault trace. In this paper we present a case study from the area hit by the Mw 6.1 April 6, 2009 L’Aquila earthquake (Central Italy), where buildings and critical lifelines located across or near the coseismic surface ruptures suffered significant damage. High resolution (1 m) LiDAR topographic data contributed to the assessment of surface faulting hazard through a better imaging of the surface geometrical arrangement of the earthquake causative fault and through the analysis of the spatial relationships between active fault splays and critical lifelines and infrastructures.

Description: Published

Description: 345-347

Description: 2T. Deformazione crostale attiva

Description: N/A or not JCR

Description: An Mw 6.1, devastating earthquake, on April 6, 2009, struck the Middle Aterno Valley (Abruzzi Apennines, Italy) due to the activation of a poorly known normal fault system. Structural analysis of the fault population and investigation of the relationships with the Quaternary continental deposits through integrated field and laboratory techniques were conducted in order to reconstruct the long-term, tectono-sedimentary evolution of the basin and hypothesize the size of the fault segment. A polyphasic evolution of the Middle Aterno Valley is characterized by a conjugate, ∼E-W and ∼NS-striking fault system, during the early stage of basin development, and by a dip-slip, NW-striking fault system in a later phase. The old conjugate fault system controlled the generation of the largest sedimentary traps in the area and is responsible for the horst and graben structures within the basin. During the Early Pleistocene the E-W and NS system reactivated with dip-slip kinematics. This gave rise to intra-basin bedrock highs and a significant syn-tectonic deposition, causing variable thickness and hiatuses of the continental infill. Subsequently, since the end of the Early Pleistocene, with the inception of the NW-striking fault system, several NW-strands linked into longer splays and their activity migrated toward a leading segment affecting the Paganica-San Demetrio basin: the Paganica-San Demetrio fault alignment. The findings from this work constrain and are consistent with the subsurface basin geometry inferred from previous geophysical investigations. Notably, two major elements of the ∼E-W and ∼NS-striking faults likely act as transfer to the nearby stepping active fault systems or form the boundaries, as geometric complexities, that limit the Paganica-San Demetrio fault segment overall length to 19 ± 3 km. The resulting size of the leading fault segment is coherent with the extent of the 6 April 2009 L'Aquila earthquake causative fault. The positive match between the geologic long-term and coseismic images of the 2009 seismogenic fault highlights that the comprehensive reconstruction of the deformation history offers a unique contribution to the understanding faults seismic potential.

Description: MIUR (Italian Ministry of Education, University and Research) project “FIRB Abruzzo - High-resolution analyses for assessing the seismic hazard and risk of the areas affected by the 6 April 2009 earthquake”, ref. RBAP10ZC8K_005 and RBAP10ZC8K_007, and by Agreement INGV-DPC 2012–2021

Description: Published

Description: 30-66

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: Rapporto Tecnico n°1 della task force operativa EMERSITO++ (INGV) che descrive le campagne sismiche ed elettromagnetiche condotte nei comuni di Casamicciola Terme e di Lacco Ameno a seguito del terremoto di Ischia del 21 Agosto 2017.

Description: INGV

Description: Published

Description: 4T. Sismologia, geofisica e geologia per l'ingegneria sismica

Description: 1SR. TERREMOTI - Servizi e ricerca per la Società

Description: N/A or not JCR

Description: Fault displacement hazard assessment is based on empirical relationships that are established using historic earthquake fault ruptures. These relationships evaluate the likelihood of coseismic surface slip considering on-fault and off-fault ruptures, for given earthquake magnitude and distance to fault. Moreover, they allow predicting the amount of fault slip at and close to the active fault of concern. Applications of this approach include land use planning, structural design of infrastructure, and critical facilities located on or close to an active fault. To date, the current equations are based on sparsely populated datasets, including a limited number of pre-2000 events. In 2015, an international effort started to constitute a worldwide and unified fault displacement database (SUrface Ruptures due to Earthquakes [SURE]) to improve further hazard estimations. After two workshops, it was decided to unify the existing datasets (field-based slip measurements) to incorporate recent and future cases, and to include new parameters relevant to properly describe the rupture. This contribution presents the status of the SURE database and delineates some perspectives to improve the surface-faulting assessment. Original data have been compiled and adapted to the structure. The database encompasses 45 earthquakes from magnitude 5–7.9, with more than 15,000 coseismic surface deformation observations (including slip measurements) and 56,000 of rupture segments. Twenty earthquake cases are from Japan, 15 from United States, two from Mexico, Italy, and New Zealand, one from Kyrgystan, Ecuador, Turkey, and Argentina. Twenty-four earthquakes are strike-slip faulting events, 11 are normal or normal oblique, and 10 are reverse faulting.

Description: Published

Description: 499–520

Description: 6T. Studi di pericolosità sismica e da maremoto

Description: JCR Journal

Description: Soil gas and Electrical Resistivity Tomography (ERT) surveys were performed in Medolla (Emilia-Romagna Region, northern Italy) within a farming area characterized by macroseeps, absence of vegetation and anomalous temperatures of soil to investigate the soil gas migration mechanism and verify the presence of a buried fault intersecting the macroseeps. Soil gas (222Rn, 220Rn, He and C2H6) concentrations and flux (φCO2 and φCH4) measurements were carried out from 2008 to 2015, comprising the 2012 Emilia seismic sequence. Moreover, in 2016 a ERT survey, combined with new flux measurements, was performed along four profiles (ranging from 180 to 630 m long) centered on the main macroseep. We found that the seismic sequence sensibly influenced the soil gas distribution in the area. All investigated species, but He, increased their values early after the mainshocks, likely due to crustal deformation which promoted the geogas uprising. In 2015, when the stress has vanished, these concentrations gradually decreased toward pre-seismic values. Helium concentrations showed an opposite behavior as they decreased in May 2012 and then gradually increased over time. This trend may be reasonably due to the enhancement of the strain field which promoted the He dissipation from soil to the atmosphere, due to its high volatility. In all the geochemical surveys conducted from 2008 to 2015, soil gas high values around the main macroseeps were identified, delighting the presence of an alignment in the E-W direction. This trend, identified for several gas species, ultimately supports the theory of a hidden fault which favors the intensification of fluids migration along zones characterized by greater permeability. ERT results highlighted a sub-horizontal layering characterized by different resistivity intervals, roughly matching local stratigraphy. In most profiles we observed a slightly increase of resistivity and a sharp inter-ruption of the electro-layering in correspondence of the main macroseep, both near the surface and at depth. This implies that a fracture zone due to the presence of a buried fault cannot be excluded. The combined use of geochemical and geophysical techniques in this study confirmed the usefulness of such multiparametric approach for mapping out hidden structures in tectonically active areas, allowing to better understanding the fluid migration processes through preferential leakage pathways.

Description: Published

Description: 106678

Description: 6A. Geochimica per l'ambiente e geologia medica

Description: 7A. Geofisica per il monitoraggio ambientale

Description: JCR Journal

Description: In order to geometrically characterize the liquefaction features observed in the epicentral sector of the 2012 Emilia seismic sequence and to evaluate the potential for recording palaeoseismic features of the area, we performed two electric resistivity tomographic sections and 4 shallow corings, coupled with 14C datings and archaeological age estimates in selected sites. Preliminary results show that there is a good agreement between ERT sections and core-logs; moreover a major role in determining the scalar relationships of the liquefaction features is played by the local geomorphological and topographic setting. The high sedimentation rates obtained through core datings (4 – 20 mm/yr) suggest that the described methodological approach can cover time windows of only a few centuries, thus hardly encompassing, in this tectonic setting, a significant period for paleoseismological purposes.

Description: Published

Description: 206-209

Description: 2T. Deformazione crostale attiva

Description: N/A or not JCR

Description: This thesis developed a multidisciplinary and multi-scale investigation strategy based on the integration of traditional and innovative approaches aimed at improving the normal faults seismogenic identification and characterization, focusing mainly on slip-rate estimate as a measure of the fault activity. The L’Aquila Mw 6.3 April 6, 2009 earthquake causative fault was used as a test site for the application, testing, and refinement of traditional and/or innovative approaches, with the aim to 1) evaluate their strength or limitations 2) develop a reference approach useful for extending the investigation to other active faults in the area and 3) translate the results of the methodological approaches into new inputs to local seismic hazard. The April 6, 2009 L’Aquila earthquake occurred on a so far poorly known tectonic structure, considered having a limited seismic potential, the Paganica - San Demetrio fault system (PSDFS), and thus has highlighted the need for a detailed knowledge in terms of location, geometry, and characterization of the active faults that are the potential sources for future earthquakes. To fill the gap of knowledge enhanced by the occurrence of the 2009 L’Aquila earthquake, we developed a multidisciplinary and multiscale‐based strategy consisting of paleoseismological investigations, detailed geomorphological and geological field studies, as well as shallow geophysical imaging and an innovative methodology that uses, as an alternative paleoseismological tool, core sampling and laboratory analyses but also in situ measurements of physical properties. The integration of geomorphology, geology as well as shallow geophysics, was essential to produce a new detailed geomorphological and geological map of the PSDFS and to define its tectonic style, arrangement, kinematics, extent, geometry and internal complexities. Our investigations highlighted that the PSDFS is a 19 km-long tectonic structure characterized by a complex structural setting at the surface and that is arranged in two main sectors: the Paganica sector to the NW and the San Demetrio sector to SE. The Paganica sector is characterized by a narrow deformation zone, with a relatively small (but deep) Quaternary basin affected by few fault splays. The San Demetrio sector is characterized by a strain distribution at the surface that is accommodated by several tectonic structures, with the system opening into a set of parallel, km-spaced fault traces that exhume and dissect the Quaternary basin. The integration of all the fault displacement data and age constraints (radiocarbon dating, optically stimulated luminescence (OSL) and tephrochronology) resulting from paleoseismological, geomorphological, geophysical and geological investigations played a primary role in the estimate of the slip-rate of the PSDFS. Slip-rates were estimated for different time intervals in the Quaternary, from Early Pleistocene (1.8 Ma) to Late Holocene (last 5 ka), yielding values ranging between 0.09 and 0.58 mm/yr and providing an average Quaternary slip-rate representative for the PSDFS of 0.27 - 0.48 mm/yr. We contributed also to the understanding of the PSDFS seismic behavior and of the local seismic hazard by estimating the max expected magnitude for this fault on the basis of its length (ca. 20 km) and slip per event (up to 0.8 m), and identifying the two most active fault splays at present. Our multidisciplinary results converge toward the possibility of the occurrence of past surface faulting earthquakes characterized by a moment magnitude between 6.3 and 6.8, notably larger than the 2009 event, but compatible with the M range observed in historical earthquakes in the area. The slip-rate distribution over time and space and the tectonic style of the PSDFS suggested the occurrence of strain migration through time in the southern sector, from the easternmost basin-bounding fault splay toward the southwestern splays. This topic has a significant implication in terms of surface faulting hazard in the area, because it can contribute defining the fault splays that have a higher potential to slip during future earthquakes along the PSDFS. By a methodological point of view, the multidisciplinary and multiscale‐based investigation strategy emphasizes the advantages of the joint application of different approaches and methodologies for active faults identification and characterization. Our work suggests that each approach alone may provide sufficient information but only the application of a multidisciplinary strategy is effective in providing robust results and in defining a proper framework of active faults.

Description: Alma Mater Studiorum – Università di Bologna

Description: Submitted

Description: 3.2. Tettonica attiva

Description: open

Description: The occurrence of the Mw 6.3, April 6, 2009 earthquake has highlighted how critical is the knowledge of the location and of the characteristics of the active faults in a seismic region. This is true not only as a contribution to the seismic hazard assessment but also for the local planning of residential areas, plants and infrastructures. The 2009 earthquake occurred on the Paganica normal fault (PF hereinafter) and produced 3 km-long, maximum 0.1 m-high surface rupture along its central section, and secondary slip along nearby tectonic structures. The PF consists of a prominent morphologic scarp formed by the tectonic juxtaposition of Pliocene-middle Pleistocene and late Pleistocene alluvial deposits, and by lower scarps in late Pleistocene-Holocene deposits. The fault, NW-SE striking and SW dipping, runs for a total length of about 20 km along the NE side of the Aterno River valley, a graben-type basin bounded by marked antithetic faults. The limited extent and the small throw of the 2009 surface ruptures, when compared to the size of the Paganica long-term fault scarp, suggest that the PF probably experienced larger Magnitude earthquakes than the 2009 seismic event. Thus, although the April 6, 2009 earthquake and associated surface faulting caused loss of lives and major damage, we believe that this event does not fully characterize the seismic hazard of the area. Therefore, a campaign of paleoseismological investigations is underway with the aim of defining the Max Magnitude, the average rate of displacement and the frequency of seismic events on the PF and on the nearby faults. An amazing “coseismic” trench, caved by the overpressure produced by the broken pipe of an aqueduct, provided the exposure of a 30-m wide fault zone of the PF. We show the preliminary results from the analysis of this site, as well as from other sites along the PF. In addition, we also present preliminary paleoseismological data from the antithetic Fossa fault. A major finding at this early stage of our field campaign is the recognition of large displacements (0.5 to 1 m) associated to individual events affecting deposits of Holocene age based on radiocarbon dating and pottery content.

Description: Published

Description: 2009 AGU Fall Meeting 14–18 December Moscone Convention Center Howard Street, Between Third & Fifth Sts. San Francisco, California, USA

Description: 3.2. Tettonica attiva

Description: open