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The Irpinia Fault (i.e., Mount Marzano Fault System: MMFS) was responsible for the devastating 1980 earthquake (Mw 6.9) that caused the longest surface faulting ever observed in Italy (> 30 km). Early paleoseismological studies have revealed a ∼ 2 kyr recurrence time for 1980-like characteristic earthquakes on this fault system during the Holocene. However, this appears to clash with both the catastrophic historical seismicity and high GPS-derived strain rate of the area. To explain this apparent discrepancy, we investigated the MMFS through a multidisciplinary approach. First, on the basis of recent archives and archaeological research, we reassessed the historical seismicity of the area, analysing the highest intensity distribution of the major earthquakes of the upper Ofanto Valley, with respect to the MMFS hanging wall. Then, we carried out a step-by-step survey along the entire 43-km-long fault system, through both high precision topographic levelling along the compound fault scarp and geostructural analyses. Finally, we excavated trenches and pits across different fault segments, to explore the recent paleoseismological history of the structure. Based on the combined results that we have obtained, we propose a different point of view concerning the seismogenic behaviour of the MMFS from the Holocene to the Present. At the end, fault parameters have been compared with those of all the Apennines active faults, and cross-checked with the newest GPS results in peninsular Italy, providing some relevant observation of the relationships between seismogenesis and geodetic deformation. [ABSTRACT FROM AUTHOR]

Abstract: Fault scarps affecting post-LGM (Last Glacial Maximum) slopes are usually seen as an indication of active tectonics, even if they can barely provide analytical data concerning single coseismic fault rupture (offset amount and age) or significant clues on the seismogenetic behaviour of the causative structure. Moreover, because of the Mediterranean climate, and of the extensive thousand year-long human reworking of the Italian landscape (i.e., the imprint of human development overrides the geomorphological signal), young fault scarps are poorly preserved in the Apennines. Nonetheless, along the active Mount Marzano Fault System (southern Italy), favourable circumstances have allowed the associated multiple-scarp to be partly protected by erosive processes, and to retain some idiosyncratic features that have resulted in a reliable tool for reconstructing the rupture history of the fault. Firstly, we have identified through topographic levelling across different sectors of this fault scarp several clusters of inflection points. Then, by comparing this succession of consecutive clusters with (1) the historical seismicity of the area and (2) the paleoseismological data that were recently acquired along some key fault segments, we offer a new point of view concerning the present slip rate and recurrence time for Mw>6.5 earthquakes caused by one of the most hazardous normal faults of the Mediterranean region (e.g., Mw 6.9, 1980 earthquake). We are confident that the method applied here would be useful in several similar tectonic and climatic contexts worldwide, enriching our knowledge on the seismic hazard of densely inhabited regions. [Copyright &y& Elsevier]

Ground motion modification over large areas is generally evaluated by focusing on source effects disregarding local lithostratigraphic site conditions. Hence, amplification maps of peak ground acceleration and peak ground velocity are proposed to improve the forecast of ground motion on a national scale. Topological information about litho-type successions and soil mechanical behaviour were retrieved from the Italian database of seismic microzonation and more than 30 million of seismic site response analyses were performed to quantify the amplification factors (i.e. the ratio between expected ground motion at the site of interest and that at the outcropping engineering bedrock). The maximum value of the amplified peak ground acceleration on the Italian territory results in about twice as much as the value expected at the outcropping of the engineering bedrock. Finally, damage scenario maps based on the amplified ground motion could be produced as a supporting tool for urban planning and emergency system management. [ABSTRACT FROM AUTHOR]

Here we present a multiproxy record (δ 13 C, δ 18 O, major and minor element composition, mineralogy, and low-resolution biogenic silica content) from a lacustrine succession in the Sulmona Basin, central Italy. Based on previous tephrochronological constraints and a new 40 Ar/ 39 Ar dating of a tephra matching the widespread X-6 tephra, the record spans the ca. 129–92 ka period and documents at sub-orbital scale the climatic and environmental changes over the Last Interglacial and its transition to the Last Glacial period. The δ 18 O composition is interpreted as a proxy for the amount and seasonality of local precipitation, whereas variations in elemental and mineralogical composition are inferred to reflect climatic-driven changes in clastic sediment input. The observed variations are consistent among the different proxies, and indicate that periods of reduced precipitation were marked by enhanced catchment erosion, probably due to a reduction in vegetation cover. The first part of the Last Interglacial shows the most negative δ 18 O values. Comparison with pollen records from the Mediterranean suggests a greater seasonality of the precipitation at this time. At millennial-to-centennial time scales, comparison of the Sulmona record with speleothem δ 18 O records from central Italy highlights a highly coherent pattern of hydrological evolution, with enhanced variability and similar events of reduced precipitation consistently recorded by each isotope record. The observed intra-interglacial variability can potentially be linked, within the uncertainties associated with each age model, to similar variations observed in sea-surface temperature records from the Mediterranean and the North Atlantic, suggesting a link between Mediterranean hydrology and North Atlantic temperature and circulation patterns that persists during periods of low ice volume. [ABSTRACT FROM AUTHOR]

An integrated investigation including geological, geomorphological, geophysical and structural survey, tephra analyses, 14 C and 40 Ar/ 39 Ar dating, as well as paleoseismic trenching along the N-Matese fault system is presented. The study allowed the characterization of the tectonic mobility of this structure as well as the associated Bojano basin sedimentary-tectonic evolution since the early Middle Pleistocene, providing also new clues concerning the fault historical activity and the associated Mw > 6.5 earthquakes. We have found lines of evidence for > 1 mm/yr slip rate along the presently buried Bojano fault during the mid Middle Pleistocene, and similar rates for the main fault segments paralleling the Matese flanks. The buried Bojano fault significantly slowed down during the last 300 kyr, ceasing its activity before the Holocene. In turn, the segments outcropping along the Matese flanks reactivated at the onset of Late Pleistocene, after a long period of quiescence (480–110 ka), with robust slip rates that would seem even accelerating in post LGM times. Paleoseismic data suggest the occurrence of four Mw > 6.6 earthquakes in the past 3 ka, three of which match the little known 280 BC event, and the devastating 1456 and 1805 earthquakes. [ABSTRACT FROM AUTHOR]

We present the first integrated tephrochronological study (major and trace elemental glass composition, Sr and Nd isotope analyses, and 40 Ar/ 39 Ar dating) for the last one tenth (∼82 m) of the ∼900 m-thick Quaternary lacustrine succession of the Fucino Basin, the largest and probably only Central Apennine intermountain tectonic depression that hosts a continuous lacustrine succession documenting the Plio-Quaternary sedimentary history up to historical times. Major element glass compositions, determined using a wavelength-dispersive electron microprobe (WDS-EMPA), yielded the geochemical fingerprinting needed for a reliable identification of most of the 23 stratigraphically ordered tephra layers under investigation. These include tephra from Italian volcanoes such as Campi Flegrei, Etna, Colli Albani, Ischia, Vico, Sabatini, and undefined volcanic sources in the Neapolitan area and Latium region. The recognition of key Mediterranean marker tephra layers (e.g. X-5 and X-6) is supported by trace element data acquired by Laser Ablation Inductively Couple Plasma Mass Spectrometry (LA-ICP-MS). The Sr and Nd isotope compositions of selected layers where also determined for circumscribing the volcanic source of distal tephra and for supporting correlations with individual eruptive units. We also propose a new, more expeditious covariation diagram (CaO/FeO tot vs Cl) for identifying the volcanic source of trachytic to phonolitic and tephrytic to phonolitic tephra, that are the most common compositions of pyroclastic rocks from volcanoes of Campania and Latium regions. Finally, we present five new 40 Ar/ 39 Ar age determinations, including a new, analytically well-supported, and more precise 40 Ar/ 39 Ar age for the widespread Y-7 tephra, and the first 40 Ar/ 39 Ar age determinations for one tephra from the Sabatini volcanic district (∼126 ka) and one tephra from Neapolitan volcanic area (Campi Flegrei?; ∼159 ka). These newly dated tephra are widely dispersed (e.g. Monticchio, southern Italy, Adriatic Sea and Lake Ohrid, Macedonia-Abania) and have thus the potential to become important Mediterranean MIS 5 and MIS 6 tephrochronological markers. Altogether the new geochemical data and 40 Ar/ 39 Ar ages precisely constrain the chronology of the investigated Fucino succession spanning the last ∼190 ka. In light of these results and by considering that this sedimentary succession possibly extends back to ∼2 Ma, Fucino is likely to provide a very long, continuous tephrostratigraphic record for the Mediterranean area and become a key node in the dense network of tephra correlations of this region. [ABSTRACT FROM AUTHOR]

New palaeoseismic trenching across the main splay of the Fucino fault system provides evidence for a High Middle Age surface-faulting episode conceivably associated with a disruptive earthquake, similar to the one that occurred in 1915 (Mw 7.0). The existence of this event, which has already been suggested by some previous studies, implies a shortening of the recurrence interval for Mw 7.0 earthquakes with respect to current knowledge. If we assume that the palaeoseismic Holocene record is complete, this shortening is focused in the historical period, when the Fucino structure sourced three strong earthquakes in only 1.4 ka. A similar clustering of energy release in the recent past is consistent with both palaeoseismological studies on other faults affecting the Apennine divide, and the high GPS strain rates observed in the same chain sectors. [ABSTRACT FROM AUTHOR]

A multi-proxy record (lithology, XRF, CaCO 3 content, carbonate δ 18 O and δ 13 C) was acquired from a sediment core drilled in the intermountain Sulmona basin (central Italy). Tephrostratigraphic analyses of three volcanic ash layers ascribe the investigated succession to the MIS 12-MIS 11 period, spanning the interval ca. 500–410 ka. Litho-pedo facies assemblage indicates predominant lacustrine deposition, interrupted by a minor sub-aerial and lake low stand episode. Variations in major and minor elements concentrations are related to changes in the clastic input to the lake. The oxygen isotopic composition of carbonate (δ 18 O c ) intervals is interpreted mainly as a proxy for the amount of precipitation in the high-altitude catchment of the karst recharge system. The record shows pronounced hydrological variability at orbital and millennial time-scales, which appears closely related to the Northern Hemisphere summer insolation pattern and replicates North Atlantic and west Mediterranean Sea Surface Temperature (SST) fluctuations. The MIS 12 glacial inception is marked by an abrupt reduction of precipitation, lowering of the lake level and enhanced catchment erosion. A well-defined and isotopically prominent interstadial with increased precipitation maybe related to insolation maxima-precession minima at ca. 465 ka. This interstadial ends abruptly at ca. 457 ka and it is followed by a phase of strong short-term instability. Drastic lake-level lowering and enhanced clastic flux characterized the MIS 12 glacial maximum. Lacustrine deposition restarted about 440 ka ago. The MIS 12–MIS 11 transition is characterized by a rapid increase in the precipitation, lake-level rise and reduction in the clastic input, interrupted by a short and abrupt return to drier conditions. Comparison with marine records from the Iberian margin and western Mediterranean suggests that major events of ice rafted debris deposition, related to southward migrations of the polar front, match the harshest periods in central Italy. This indicates strong teleconnections between Northern hemisphere ice sheet dynamics, North Atlantic oceanic conditions and Mediterranean continental hydrology. [ABSTRACT FROM AUTHOR]

Abstract: Morphological, stratigraphical and structural investigations integrated with palaeomagnetic and tephrostratigraphic studies and 40Ar/39Ar measurements allowed us to define the Quaternary tectonic–sedimentary evolution of the epicentral area of the L''Aquila 2009 earthquake (Mw 6.3). This area roughly matches the Paganica–San Demetrio–Castelnuovo (PSC) intermountain basin filled by a fluvio-lacustrine succession that is variously deformed by normal faults. At its early stage (Early Pleistocene; ca 2 Ma), the basin hosted a lake that was characterised by whitish carbonate silt and mud deposition. Towards the end of the Early Pleistocene, this was partly filled by a south-eastward prograding deltaic system. The south-easternmost portion of the deltaic system was successively abandoned and eroded, while sedimentation of a braided river system developed in a smaller area westwards. Before 780 ka, this fluvio-lacustrine system (the Lower PSC syntheme) ended, and the area underwent erosional and pedogenic processes. These processes continued up to >460 ka, with the onset of fluvial gravel and volcanic-rich silty sand deposition over a narrow area of the south-western PSC basin (an earlier unit of the Upper PSC syntheme, early Middle Pleistocene). Around 460 ka, when most of this area was again subjected to denudational processes, the sedimentation migrated into the previously exposed north-western area of the PSC basin, where fluvial/alluvial sediments were deposited, between ca 460 ka and ca 350 ka (a later unit of the Upper PSC syntheme). Between ca 350 ka and the present, the sedimentation continued uninterrupted in a slight westwards restricted area of the PSC basin (Upper–Late PSC syntheme). The significant contraction of the basin, the shifting of its depocentre, the variation in its geometry and in the spatial distributions and thicknesses of the units constituting the Lower, Upper and Late PSC synthemes, provide evidence for strong tectonic control. This resulted in progressive reduction of the activity of the south-easternmost tectonic structures and parallel migration of the fault activity on the westernmost structures. In this perspective, the fault system responsible for the L''Aquila 2009 earthquake can be seen as the most recent expression of a long-lasting westwards polarised process of tectonic activity transfer. [Copyright &y& Elsevier]

SUMMARY Urgent urban-planning problems related to the 2009 April, Mw 6.3, L'Aquila earthquake prompted immediate excavation of palaeoseismological trenches across the active faults bordering the Aterno river valley; namely, the Mt. Marine, Mt. Pettino and Paganica faults. Cross-cutting correlations amongst existing and new trenches that were strengthened by radiocarbon ages and archaeological constraints show unambiguously that these three investigated structures have been active since the Last Glacial Maximum period, as seen by the metric offset that affected the whole slope/alluvial sedimentary succession up to the historical deposits. Moreover, in agreement with both 18th century accounts and previous palaeoseismological data, we can affirm now that these faults were responsible for the catastrophic 1703 February 2, earthquake ( Mw 6.7). The data indicate that the Paganica-San Demetrio fault system has ruptured in the past both together with the conterminous Mt. Pettino-Mt. Marine fault system, along more than 30 km and causing an Mw 6.7 earthquake, and on its own, along ca. 19 km, as in the recent 2009 event and in the similar 1461 AD event. This behaviour of the L'Aquila faults has important implications in terms of seismic hazard assessment, while it also casts new light on the ongoing fault linkage processes amongst these L'Aquila faults. [ABSTRACT FROM AUTHOR]

We investigated the late Upper Pleistocene activity of the eight main faults that comprise the active, dip-slip Gran Sasso fault system (GSFS) in the Gran Sasso d'Italia Massif (central Italian Apennines; 2912 m a.s.l.). We carried out novel paleoseismological analyses at four sites of three different fault segments, and reviewed the data of the previous results for three other segments. We carried out several topographic profiles across the offset hillslopes, alluvial fans, glacial cirques, moraines, and valley floor. Through the dozen radiocarbon datings that were combined and cross-checked with many other ages published in previous studies, we have provided robust slip-rates and reconstructed the Holocene seismic history of this fault system. Paleoseismic analyses revealed the presence of three consecutive earthquakes since the onset of the Late Holocene, which were separated by 3.3 ky and 2.2 ky, respectively. The last one occurred in the 13th–14th century CE, a time-span that fits with the catastrophic 1349 seismic sequence. Our review of the macroseismic intensity distribution of this sequence indicates the existence of two distinct mesoseismic areas; a southern one that was already related to the Aquae Iuliae fault rupture (Abruzzi-Campania-Molise borders), and a northern one that robustly matches the hanging-wall of the Gran Sasso fault system. Given the length of this fault system, we estimated Mw 7 for its entire rupture, which accounts for the total destruction of L'Aquila and the neighboring villages. This also accounts for the strong effects and severe damage suffered by several settlements in the para-Tyrrhenian far field, especially to buildings characterized by long fundamental resonance periods, as seen for the monuments of Rome. Although characterized by long recurrence times (2.8 ± 0.5 ky), our results suggest that as for all of the main silent faults of the eastern set of active structures in the central Apennines, this fault system has one of the largest seismogenic potentials of the whole Apennine chain, with seismic risk implications extended even to its far-field. • Paleoseismic trenching reveals the Holocene seismic history of the Gran Sasso fault. • Coseismic surface rupture length indicates a Mw 7.0 seismogenic potential. • The Gran Sasso fault rupture caused severe damage in Rome in the 1349 earthquake. [ABSTRACT FROM AUTHOR]

Prediction of surface ground motion based on advanced approaches is a non-trivial task at large area. In fact, advanced approaches require a detailed geological and geotechnical subsoil model based on geological, physical and mechanical properties retrieved from in situ investigations and laboratory data, and to perform time consuming numerical simulation of the seismic site response. Bearing in mind that there is a lack of available site investigations and laboratory data at large area, simplified methods based on "soft data" are often adopted. On this regard, a methodology to perform seismic site response analyses at national scale is proposed in this paper, based on the following assumptions: 1) homogeneous areas were identified at national scale based both on morpho-geological and lithological properties, in order to classify and analyse site-data archived in the Italian database of seismic microzonation studies; 2) geotechnical subsoil one-dimensional models of the Italian site conditions were defined according to site-data; 3) in accordance with the reference seismic hazard levels, pseudo-acceleration response spectra were selected as input motions for numerical simulations. About thirty million numerical simulations of seismic site response were performed, and national maps of seismic shaking amplification factors were produced in terms of ratio of response spectra referred to three intervals of period. This estimation of surface ground motion based on the proposed procedure is a supporting tool for large area territorial and emergency planning. • Numerical models of national site conditions were identified from Italian database. • Numerical models were extended down to the seismic bedrock. • Morpho-geological clusters were used to spatialize input and output data. • National maps of amplified seismic intensity were proposed. • The proposed procedure will support seismic risk mitigation at large area. [ABSTRACT FROM AUTHOR]

Evaluation of bedrock stiffness and thickness effect on ground motion modification represent a key-issue in the perspective of seismic risk reduction policy, since the maximum depth of site prospection generally does not extend down to the stiff bedrock location. Site conditions were identified from the Italian database of seismic microzonation studies. Simplified and realistic numerical models were adopted, i.e. extended down to the soft and stiff bedrock, respectively, in order to perform seismic site response analyses. Results indicate that simplified numerical model provides a quantification of the surface ground motion modification with an error generally equal to ±10% with respect to the realistic model. Hence, the evaluation of seismic performance of sites based on simplified numerical models represents a support tool for seismic risk management at large area. • Numerical models of national site conditions were identified from Italian database. • Simplified numerical models were extended down to the soft geological bedrock. • Realistic numerical models were extended down to the stiff seismic bedrock. • Simplified numerical models can support seismic risk management and urban planning. • Impedance contrast between shallow bedrock layers affect the numerical input motion. [ABSTRACT FROM AUTHOR]

Total seismic hazard assessment (i.e. the base hazard modified by local site conditions) plays a key role in seismic risk prevention and mitigation. This is an important topic due to the impact of a reliable hazard assessment on the resilience of local communities in the case of an earthquake. This paper presents a study that evaluates the total seismic hazard for the entire Italy (excluding the Island of Sardinia). The results are expressed in terms of amplification factors and total hazard parameters. To this end, soil characterisation was performed, firstly using Italian Seismic Network data for 259 sites uniformly distributed across Italy, and secondly using the mean value of the shear wave velocity, available from a global dataset produced by the United States Geological Survey. The amplification effects were quantified according to i) an approach consistent with the Italian Building Code; and ii) one-dimensional site response analyses. These two procedures are referred to as "parsimonious" and "rigorous" here, respectively. The results indicate a generally satisfactory match between the estimates obtained by means of these two procedures for periods lower than 0.5 s, while parsimonious procedures at periods longer than 0.5 s provide an upper limit on the total seismic hazard. Finally, a seismic classification in terms of the classes of total hazard parameters is proposed for the Italian peninsula area. • Prediction of shear wave velocity was cross-checked against data from Italian sites; • The total seismic hazard was satisfactory estimated based on "poor" data; • Basic procedures can be used for a precautionary estimate of total seismic hazard; • National maps of the total seismic hazard were proposed; • Total seismic hazard maps can support urban planning and seismic risk mitigation. [ABSTRACT FROM AUTHOR]

• The seismic compression is a phenomenon producing surface permanent ground settlements in dry cohesionless soils. • Evaluation of the induced permanent surface settlements due to the seismic compression. • Proposing charts based on non-simplified uncoupled approach. • The non-simplified uncoupled approach integrates a parametric study of 1D site response analyses • The cyclic shear strain profile is correlated to the expected volumetric strain to estimate the surface settlements. Seismic microzonation studies (hereafter SMs or SM studies) have a strategic application in land use planning in the perspective of territory protection. At urban scale, SMs are finalized to forecast the spatial distribution of stratigraphic and topographic local amplification effects of ground motion and the co-seismic instabilities such as landslides or liquefaction phenomena. In this regard, the co-seismic instability due to the seismic compression (or densification) in dry loose sands, silty sands and sandy silts has been addressed in this paper through a numerical approach in order to provide simplified charts to evaluate the effect of the instability in terms of earthquake-induced settlements to be incorporated in SMs. In specific subsoil conditions, seismic cyclic loads can result in contractive volumetric strains inducing damages to structures, infrastructures and lifelines, accordingly with well documented post-earthquake damages of past events. In the present work, a procedure has been adopted to define the abovementioned simplified charts to predict the possible effect of the phenomenon in terms of soil permanent displacements. The proposed charts provide the estimation of settlements in function of three different PGA classes, the thickness of the soil layer susceptible to seismic compression/densification, its relative density and shear wave velocity. The proposed charts have been tested for the case study of Santa Clarita valley (California) during the 1994 Northridge earthquake, probably the best documented seismic compression case history available in the technical literature. [ABSTRACT FROM AUTHOR]

This work provides new insights on the use of a combined multidisciplinary approach forestimating trend and rates of valley incision in tectonically active mountainouslandscape. To this aim, here we present the results of a combined analysis includingstream terraces investigation, longitudinal profiles modelling and time-dependent,catchment-scale, geomorphometry obtained in the headwater sector of the Tronto River basin,located in the southern epicentral area of the 2016-2017 seismic sequence of CentralItaly.The most relevant tectonic structures in the area are the Mt. Gorzano fault (south-easternsector), the Sibillini Mts thrust (western sector) and the southern tip of the active Vettorefault, ie the seismogenic structure responsible for the 2016 mainshock. Geomorphometric analysis and stream long-profiles modelling were performed using a 5m-gridded DTM obtained starting from the altimetric dataset included in the 1:5,000topographic maps available for the whole study area in vector format. Time-dependentcatchment-scale R∕Sr metrics and long-profile indices (SL and χ) were computedrespectively using the hydrological tool in ESRI® ArcGIS and the TopoToolboxworking in Matlab®. Stream terraces dataset derives from field survey, integrated withthe visual inspection of a DTM-derived hillshade map and aerial/satellite imageryinterpretations. The combination of R∕Sr time-dependent metrics and stream terraces analysis allows toinfer the timing of the base level changes during upper Quaternary and the long-profilesmodelling provided interesting results for better comprehending the effects of these changeson the fluvial system. The analysis here performed provided new data useful for betterunderstanding the trend and rates of the valley deepening in the headwater sector of theTronto River, to reconstruct basin-scale modifications such as stream captures and, more ingeneral, resulted useful for better comprehending the morphoevolution of this tectonicallyactive key area of the Apennines. Nonetheless, our study did not allow to unravel therole exerted by the single active tectonic structures in the present and past fluvialmorphodynamics, because of the superimposed effects of large gravitational rock slopefailures on the spatial pattern of long-profiles anomalies and local base level variations. [ABSTRACT FROM AUTHOR]