Search

Biodegradable and potentially biobased polyesteramide oligomers (PEA-Pro), obtained from melt condensation of sebacic acid and 3-amino-1-propanol, were characterized by nuclear magnetic resonance (NMR), matrix assisted laser desorption/ionization-time of flight/time of flight-mass spectrometry/mass spectrometry (MALDI-TOF/TOF-MS/MS), thermogravimetric analysis (TGA), and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). NMR analysis showed the presence of hydroxyl and amino terminal groups as well as carboxylic groups of the sebacate moiety. Hydroxyl and carboxyl termination had the same abundance, while the amine termination was 2.7-times less frequent. Information regarding the fragmentation pathways and ester/amide bond sequences was obtained by MALDI-TOF/TOF-MS/MS analysis performed on sodiated adducts of cyclic species and linear oligomers. Different end groups did not influence the observed fragmentation. Three fragmentation pathways were recognized. The β-hydrogen-transfer rearrangement, which leads to the selective scission of the –O–CH2– bonds, was the main mechanism. Abundant product ions originating from –CH2–CH2– (β–γ) bond cleavage in the sebacate moiety and less abundant ions formed by –O–CO– cleavages were also detected. TGA showed a major weight loss (74%) at 381 °C and a second degradation step (22% weight loss) at 447 °C. Py-GC/MS performed in the temperature range of 350–400 °C displayed partial similarity between the degradation products and the main fragments detected in the MALDI-TOF/TOF-MS/MS experiments. Degradation products derived from amide bonds were related to the formation of CN groups, in agreement with the literature.

The presence of a set of well-known turbidite successions, deposited in progressively E-migrating foredeep basins and subsequently piled up with east vergence, makes the Northern Apennines of Italy paradigmatic of the evolution of deepwater fold-and-thrust belts. This study focuses on the early Apenninic collisional stage, early Miocene in age, which led to the accretion of the turbidites of the Trasimeno Tectonic Wedge (TTW), in the central part of the Northern Apennines. Based on the interpretation of previously unpublished seismic reflection profiles with new surface geology data and tectonic balancing, we present a detailed tectonic reconstruction of the TTW. In the study area, the TTW is characterized by a W-dipping shaly basal décollement located at a depth of 1–5 km. The tectonic wedge isc. 5 km thick at its central-western part and tapers progressively eastwards toc. 1 km. The total shortening, balanced along a 33 km long cross-section, isc. 60 km, including 20 km (40%) of internal imbrication,c. 23 km of horizontal ENE-wards translation along the basal décollement andc. 17 km of passive translation caused by the later shortening of footwall units. Deformation balancing, constrained through upper Aquitanian – upper Burdigalian (c. 21–16 Ma) biostratigraphy, provides an average shortening rate ofc. 8.6 mm a–1. Internal shortening of the TTW shows an average shortening rate ofc. 4 mm a–1for this period.

The interaction between fluids and tectonic structures such as fault systems is a much-discussed issue. Many scientific works are aimed at understanding what the role of fault systems in the displacement of deep fluids is, by investigating the interaction between the upper mantle, the lower crustal portion and the upraising of gasses carried by liquids. Many other scientific works try to explore the interaction between the recharge processes, i.e., precipitation, and the fault zones, aiming to recognize the function of the abovementioned structures and their capability to direct groundwater flow towards preferential drainage areas. Understanding the role of faults in the recharge processes of punctual and linear springs, meant as gaining streams, is a key point in hydrogeology, as it is known that faults can act either as flow barriers or as preferential flow paths. In this work an investigation of a fault system located in the Nera River catchment (Italy), based on geo-structural investigations, tracer tests, geochemical and isotopic recharge modelling, allows to identify the role of the normal fault system before and after the 2016–2017 central Italy seismic sequence (Mmax = 6.5). The outcome was achieved by an integrated approach consisting of a structural geology field work, combined with GIS-based analysis, and of a hydrogeological investigation based on artificial tracer tests and geochemical and isotopic analyses.

We have investigated the structural, thermal and morphological properties of lignin extracted from five distinct biomasses in order to establish the influence of the age of the source, environmental conditions during growth and quantity present. In fact, lignin is an integral part of cellulosic biomass and affects the structure, properties, processing and applications. Presence of lignin is critical for structural integrity but detrimental for converting biomass into new products. Aerial roots from banyan tree, sugarcane bagasse, bamboo, cornhusk and rice straw were selected to extract Klason lignin using the sulfuric acid approach. Extent of lignin in the samples varied from 9.14 to 23.77 %. Overall, compositional analysis showed that the lignin from the five sources had considerable variation, particularly in terms of the trace elements. Nevertheless, structure and properties of lignin extracted from five distinct biomasses was found to be independent of the age of the source, conditions during growth or quantity present in the biomass.

The dynamic of groundwater systems feeding several springs of the Sibillini Mountains was deeply affected by nine Mw 5.0÷6.5 seismic events occurred in central Italy starting from August 2016. The strongest shock occurred on October 30th 2016 about 5 km NNE of Norcia Town, 9 km below the surface, as a result of upper crust normal faulting on the nearly 30 km-long Mt Vettore - Mt Bove fault system, a NW-SE trending, SW-dipping fault system outcropping on the western slope of Mt Vettore, the highest peak of Sibillini Mountains. Soon after this event, a general increase of springs and rivers discharge and groundwater levels was observed both in the Visso and Norcia areas, west of the Sibillini Mountains. In the Visso area the hydrogeological changes due to the seismic sequence exhausted in the 2019, while nowadays both discharges and groundwater levels are still higher than before in the Norcia area. Discharge data of the main springs located east, south-east of the Sibillini Mountains were analysed to verify whether the general increase observed on the western side was associated to a decrease on the eastern and southern-east area. The results show that the springs located on the eastern side and southern-east side of Mt Vettore experienced a significant long-term discharge decrease. In this preliminary work, the analysis of the historical discharge series of the Pescara di Arquata spring (SE of Mt Vettore), and its relationship with the Standard Precipitation Index (SPI) shows that the very low discharge values recorded during the post-seismic period are not associated with SPI as low as documented in the past for similar discharges. Moreover, the stable isotopic composition of Pescara di Arquata water during the post-earthquake period is slightly different from that measured before the seismic events; this suggests that a lower amount of water having more enriched isotopic δ18O content reaches the spring after the seismic sequence. These aspects seem to indicate that groundwater circulation in the southern-east area of Sibillini Mountains has been affected by the 2016-2017 seismic sequence.

Starting from 24 August 2016, a long seismic sequence, including nine M-w > 5.0 earthquakes, struck a wide area of the Central Italy. A large amount of geological, geodetic, and seismological data envisages a complex system of NNW-SSE trending, seismogenic normal faults. These active tectonic structures are well known at the surface and consistent with previous seismotectonic studies. In order to improve the comprehension of the seismotectonic framework of this seismic sequence, we provide a novel reconstruction of the subsurface geology of the area close to the Norcia M-w 6.5 mainshock (30 October 2016), based on previously unpublished seismic reflection profiles and available geological data. All the data have been synthesized along a 47 km long, WSW-ENE trending geological cross section, interpreted down to a depth of 12 km. Comparing the subsurface geological model with the available seismological data, we find that the majority of seismicity is confined within the sedimentary sequence and does not penetrate the underlying basement. The basement has been constrained at depths of 8 to 11 km and coincides with the cutoff of the seismicity. We have also traced the trajectories of the seismogenic normal faults activated during this seismic sequence, reconciling the high-angle (dip>65 degrees) normal faults exposed at the surface, with their angle (dip < 50 degrees) at hypocentral depths. The results of this study may be useful for better understanding the rheological properties of the seismogenic rock volume, as well as the coseismic deformations of the topographic surface observed by geodetic techniques and field mapping.

During the last years, there has been an increasing interest in the valorization of the food-processing side streams due to their potentially valuable phytochemical content. Olive mill wastewater (OMWW), the main by-product of olive oil extraction process, are rich in polyphenolic compounds, widely known for their health-promoting benefits. However, different parameters--such as the distinct olive cultivar, ripeness of the fruit, processing techniques, climate, and storage conditions--play an important role in determining the specific quali-quantitative polyphenolic composition of OMWW. In this work, for the first time, we have characterized and compared the polyphenolic profile of different OMWW generated by centrifugal three-phase olive oil mills processing of two important Sicilian cultivars, Cerasuola and Nocellara etnea. Moreover, the correlated antioxidant activity and the stability of both OMWW samples stored at different conditions were evaluated. Our results show that even if OMWW are characterized by different and individual polyphenolic profile, both side streams have high levels of antioxidant activity. From a comparative point of view, we found that Cerasuola-OMWW showed higher values of total phenols (5.20 ± 0.21 g/l gallic acid), total flavonoids (2.28 ± 0.23 g/l catechin) and hydroxytyrosol content (821.86 ± 0.01 mg/l) respect to the analog parameters measured in Nocellara etnea-OMWW; these phytochemical values showed a significant stability in both OMWW samples stored at -20 °C for 6 months. Conversely, a decrease in the level of these compounds was observed in samples maintained at 4 or 25 °C for 45 days.

New functionalized Poly(ether sulfone)s having different molar ratio (10, 20, 30, 50, 70, 100 mol%) of 4,4-bis phenoxy pentanoic acid unit (diphenolic acid, DPA) units were synthesized and characterized by (1H and 13C)-NMR, MALDI-TOF MS, FT-IR, DSC and DMA analyses. The microstructural analysis of the copolymers, obtained by 13C-NMR using an appropriate statistical model, shows a random distribution of copolymer sequences, as expected. The presence of different amount of DPA units along the polymer chains affects the chemical and physical properties of the copolymers. The Tg and the contact angle values decrease as the molar fraction of DPA units increases, whereas the hydrophilicity increases. NMR and MALDI-TOF MS analyses show that all polymer chains are almost terminated with hydroxyl and chlorine as end groups. The presence of cyclic oligomers was also observed by MALDI-TOF MS analysis.

The Middle Valle Umbra (central Italy) is a NW-SE 20 km long and 10 km wide Quaternary extensional basin located in the internal sector of the Apennine chain. This area historically experienced strong earthquakes that caused significant damages to the outstanding historical heritage. The same area has been recently hit by the 2016 seismic sequence of Amatrice-Visso-Norcia. With the aim to reconstruct the buried geological structures of the basin, a multi-technique geophysical approach was performed. An extended campaign of ambient noise measurements was carried out to investigate the subsurface setting, and to identify the main geological units. We performed three 2D passive arrays to analyze two different sites within the basin; their aperture was between 150 and 752 m for one site and of 48 m for the other site, to characterize the geological units in terms of sediment thickness and shear-wave velocity profile. Data collected were processed with f-k and MSPAC analysis to extract dispersion curves with good resolution in a frequency range of 0.5–10 Hz and 4.5–18 Hz for the two sites respectively. Spectral ratios were computed for every single station ambient noise measurement performed and for all the stations of the bigger array. Our final target is to extend these results to the whole valley, in order to retrieve the attitude of the main geological units and propose a reliable reconstruction of the subsurface geometry of the basin. Another point of this work is to evaluate the site response in the middle of the valley through the analysis of the earthquakes recorded by the accelerometric station IT.CSA (belonging to the Italian Civil Protection) and the corresponding recordings of the nearby rock station IT.ASS.

Co-seismic changes in groundwater regime are often observed after moderate to strong earthquakes. The 24 August 2016 Mw 6.0 extensional Amatrice earthquake, which was the first event of a long-lasting seismic sequence, including the 30 October 2016 Mw 6.5 Norcia event, triggered a significant discharge alteration to the Pescara di Arquata spring, located in the Umbria-Marche Apennines (Northern Apennines, Central Italy) and exploited for drinking purposes. During the first five months after the first mainshock, an extra flow of about 30% was recorded, while both water chemistry and temperature did not show significant changes. Thereafter, the spring discharge decreased significantly, and at the end of 2019 it was still lower than normal. The Standardized Precipitation Index (SPI) indicates that these low mean monthly discharge values are not related to particularly dry conditions. The increase in post-seismic depletion coefficients indicates that the aquifer empties faster than it did during the inter-seismic period. The observed transient increase and subsequent decrease of discharge are consistent with a transient, earthquake-related increase in hydraulic conductivity.

In this paper, the amount of polyethylene (PE) contained in complex biodegradable polymer blends and in carrier bags claimed to be compostable was determined by thermogravimetry analysis (TGA) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). To validate the method, polymer blends based on polylactide (PLA), poly(butylene adipate-co-butylene terephthalate) 53/47 (PBAT), native starch (NS), and calcium carbonate, with known amount of PE ranging from 0 to 10%, were prepared by melt mixing. Py-GC/MS parameters were optimized. In the first step at 400 °C, pyrolysis products originated from thermal cracking of PLA, NS and PBAT were detected. In the second step carried out at 500 °C, triplet peaks characteristic for PE, consisting of α,ω-dienes, α-alkenes and n-alkanes, were revealed together with some signals related to PBAT. TGA under nitrogen atmosphere was used to determine the amount of PE in the blends. An overestimation of about 1.2%, constant for all the blends, was revealed. The overestimation was attributed to the partial overlapping of one of the steps of degradation of the commercial PBAT and that of PE. Additionally, the analytical approach was applied in the characterization of carrier bags claimed to be compostable, recovered directly from the market. The correct determination of the composition of these biodegradable blends is important and crucial to comply with the compostability standard EN 13432-2000. According to this standard, each significant organic constituent of the packaging material must be biodegradable. “Significant” means any constituent present in more than 1% of dry weight of that material. This implies that maximum allowed PE concentration that can be detected in a compostable blend is 1%. In two commercial carrier bags, TGA revealed a component with a degradation temperature of about 455 °C corresponding to that of PE. The relative weight loss percentages of these two carrier bags have been estimated 7.6 and 14%. Optimization of the Py-GC/MS conditions allowed identifying its chemical structure. In fact, the Py-GC/MS at 500 °C provided a pyrogram that was a fingerprint for PE with triplets corresponding to linear chains of α,ω-dienes, α-alkenes and n-alkanes with chain lengths in the range of 9–36 C atoms. Overall, the results show that the combination of TGA and Py-GC/MS can be applied with practical implications.

Subsidence over the last 0.78 myr of a basin in central Italy bounded by a normal fault caused the deactivation and uplift of an Early–Middle Pleistocene alluvial fan at the fault footwall. Uplift of the fan occurred with a basin-bounding fault slip-rate of the order of 0.2 mm a −1 . Subsidence resulted in the reorganization of the river network due to a fall in base level, which triggered headward erosion, stream piracy effects and drainage inversion. The mapped river inversions and catchment piracy were related to the distribution of a quantile regression of 134 alluvial fans v. basin areas. Despite the fact that the two parameters were well fitted by a power law relationship, all the fans corresponding to the captured rivers lay above the regression line (in the fan area field), whereas those corresponding to the capturing rivers were below the regression line (in the basin area field). We propose a general model of alluvial fan growth in active extensional settings that helps to interpret this scatter of fan v. basin area distribution and to identify the most active fault segments. Such an approach can better constrain fault activity in a time window that bridges long-term deformation and the present day deformation inferred from geodesy and/or seismology, increasing our understanding of the steadiness/unsteadiness behaviour of faults.

Seismic reflection data are used to reconstruct the subsurface geologic structures below the Umbria-Marche region in Italy, a highly seismogenic area with a recent history of seismic activity (the 1997–1998 Colfiorito sequence). We reprocess three vibroseis seismic profiles (acquired in the early 1980s for hydrocarbon exploration) whose stacked sections were optimized for relatively deep oil targets. On the reprocessed seismic profile closest to the epicentral area, we construct the main reflectors to a depth of about 4 s (two-way time) and compare this interpretation with the available hypocenters of the 1997 earthquakes. The improvements in visualizing the shallow and deep reflections provide a better correlation between the reflectors and the observed surface structures as well as a better delineation of the basement-rock geometry. We find that part of the Colfiorito sequence is localized around some of the reflectors in the reflection profile, which we interpret as related to the active normal faults that outcrop at the surface.

A multi-method approach (palaeothermal and thermochronological analyses; thermal modelling) is applied to reconstruct the exhumation history of the Altotiberina Fault (ATF), a representative example of crustal-scale active low-angle normal faulting in the Northern Apennines (Italy). Thermal maturity and thermochronological data yield similar burial histories but different exhumation patterns for the sedimentary successions in the hangingwall and the footwall of the ATF. Since 3.8 Ma, the ATF footwall has exhumed at rates of 0.90 mm a-1. Exhumation led to bending and deactivation of the ATF uppermost portion as a result of tectonic unloading and isostatic adjustment, followed by migration of extension and the development of a set of domino-like, east-dipping normal faults, rooting on the buried portion of the ATF. ATF activity and isostatic rebound exhumed Triassic rock units from depths of about 4 km. We suggest that isostatic instability is accommodated at shallow crustal levels, in a similar way to what is observed on larger structures at mid-low crustal levels.

The availability of multidisciplinary and high-resolution data is a fundamental requirement to understand the physics of earthquakes and faulting. We present the Alto Tiberina Near Fault Observatory (TABOO), a research infrastructure devoted to studying preparatory processes, slow and fast deformation along a fault system located in the upper Tiber Valley (northern Apennines), dominated by a 60 km long low-angle normal fault (Alto Tiberina, ATF) active since the Quaternary. TABOO consists of 50 permanent seismic stations covering an area of 120 × 120 km2. The surface seismic stations are equipped with 3-components seismometers, one third of them hosting accelerometers. We instrumented three shallow (250 m) boreholes with seismometers, creating a 3-dimensional antenna for studying micro-earthquakes sources (detection threshold is ML 0.5) and detecting transient signals. 24 of these sites are equipped with continuous geodetic GPS, forming two transects across the fault system. Geochemical and electromagnetic stations have been also deployed in the study area. In 36 months TABOO recorded 19,422 events with ML ≤ 3.8 corresponding to 23.36e-04 events per day per squared kilometres; one of the highest seismicity rate value observed in Italy. Seismicity distribution images the geometry of the ATF and its antithetic/synthetic structures located in the hanging-wall. TABOO can allow us to understand the seismogenic potential of the ATF and therefore contribute to the seismic hazard assessment of the area. The collected information on the geometry and deformation style of the fault will be used to elaborate ground shaking scenarios adopting diverse slip distributions and rupture directivity models.

Storage of CO 2 and, in particular, geological storage is one of the most promising solutions to counteract the continued increase of anthropogenic greenhouse-gas emissions. Here we present a multidisciplinary study of a natural CO 2 geologic reservoir where fluid overpressure, measured at 85% of the lithostatic load, is trapped at ∼4700 m depth in the Northern Apennines of Italy. Deep borehole data and seismic reflection profiles show that the observed CO 2 overpressure: (a) is hosted in dome shaped structures that are the result of the interplay between the compressional and extensional tectonic phases of the area and (b) occurs within dolostones that are sealed by Ca-sulphates (anhydrites) horizons. Field studies on outcropping evaporites, that represent exhumed analogues of the lithologies found at depth in the pressurized reservoir, show dolostones affected by fracturing and faulting and Ca-sulphates characterized by ductile folding without macroscopic fractures. Borehole and laboratory P-wave velocities coincide for anhydrites (6.2–6.3 km/s) but are different for dolostones (6.2–6.3 km/s in situ and ∼7.2 km/s in lab), confirming the different mode of deformation in the two rock types. Since anhydrites are not dominated by fractures, the very low permeability values, ∼10 −19 to ∼10 −22 m 2 , recorded in laboratory experiments, can also be representative for in situ conditions. These data confirm the sealing ability of the anhydrites also for high values of fluid pressure. The integration of these datasets suggests that: (1) tectonics and structural position, and (2) lithology and associated mode of deformation, play a key role for channelling and trapping deep-seated CO 2 -rich crustal fluids.

[1] We reconstruct the subsurface geology in a region of the northern Apennines (central Italy) where a protracted extensional sequence occurred in 1997–1998 with maximum magnitude M = 6.0. Our study is mainly based on the interpretation of three reprocessed seismic reflection profiles crossing the epicentral area, which constrain the subsurface geometry to a depth of about 12 km where most of the shallow seismicity occurs. Comparing the subsurface setting with accurately determined earthquake locations, we find that the seismicity is located entirely within the sedimentary cover and does not penetrate the underlying basement. This is explained by considering that the sedimentary cover is rather thick and composed of relatively strong lithologies (platform carbonates and evaporites), while the upper part of the basement consists of weak phyllites and siliciclastic rocks. This weak horizon is also evidenced by the low-Vp values measured in deep wells of the region. Its effect is to decouple the sedimentary cover from the crystalline basement, where only microseismicity occurs. Our study indicates that local structure and stratigraphy can significantly influence the distribution of seismicity within the upper crust, particularly in complex geological environments such as thrust-and-fold belts.

[1] The northern Apennines of Italy are characterized by a complex Tertiary tectonic history, where superposed compressional and extensional deformation occurred. In such regions, characterized by low active extensional strain rate, the coseismic surface ruptures are rare and often a matter of much debate resulting in a difficult connection between “geological” faults (i.e., faults which can be mapped at the surface) and “seismological” faults (i.e., faults which actually generate earthquakes). The availability of detailed geological mapping and high-resolution seismological data for the Colfiorito area, struck in 1997 by a sequence of six 5 < Mw ≤ 6 normal faulting earthquakes, allow us to compare and verify the existence of geometric and kinematic correspondence between the mapped geological Quaternary faults and the activated structures. In map view, the earthquakes distribution reflects the fault pattern mapped at the surface, the length of activated and mapped faults is quite similar (7–10 km), the coseismic subsided region imaged by interferometric synthetic aperture radar data, is located in the hanging wall of the mapped normal faults that bound the Quaternary basins. In section view, there is a geometric connection between mapped normal faults and the aftershock alignments used to image fault geometry at depth. Comparison of striated fault planes and aftershock focal mechanism solutions show a strong kinematic consistency. This study points out that the Quaternary tectonosedimentary evolution and the present-day geological and geomorphologic setting of the Colfiorito area can be interpreted as the result of repeated, extensional earthquakes, similar to the 1997 events, occurring on NW-SE trending normal faults. Our data also show that the main shocks of the Colfiorito sequence nucleated close to the intersections between the normal faults and the preexisting compressional/transpressional structures, which in 1997 acted as lateral barriers to rupture propagation and consequently constrained the fault size.

Nowadays easy accessibility to Information Technologies through Internet and the availability of satellite positioning systems discloses new perspective to geological survey and mapping procedures. The GNU project together with Linux kernel has made available a completely free operating system together with development facilities. This leads researchers to participate actively to software development, sometimes being developers themselves or by funding the development of Free Software. The freedom to use, distribute, study, and modify the software makes it possible to use and adapt to specific geological requirements the leading generic Geographical Information System (GIS) and mapping projects as the Geographic Resources Support System (GRASS GIS) and the Generic Mapping Tools (GMT). Our contribution presents a complete workflow focused on geological mapping activity: from survey to processing/visualization to print-ready map-making. A structural geology mapping and a riverbed-alluvial plain system morpho-sedimentary mapping are presented to test the suitableness of the chosen working environment. In this way, we are forced to abstract specific needs from general requirements. Field survey activities have been carried out with the aid of a Global Positioning System (GPS) receiver and a Personal Digital Assistant (PDA) device put together in a free GPS/PDA software that associates geological data and observations with their respective geographical position. Also, digital camera shots have been geographically registered through EXIF IFD tags and included in the survey databases. Statistical analysis has been done directly on surveyed data inside the geographical/geological database using the R statistical analysis package, avoiding import/export procedures. Finally, print-ready maps have been produced. Correct letter signs, colors, and symbols are used to produce congruous maps. LaTeX typesetting language has been used for detailed, congruous, and well-typeset legends. The use of Free Software gives direct control over every step of the process. In this way we have a solid base to develop features we need and, whenever more efficient new solutions are available, we are able to implement them in the working environment without needing to change the whole. This work, done with the intensive use of Information Technologies, is firmly scientist-centered so that software conforms to the research process and not vice-versa.

Different investigation techniques (field geology and structural analysis, geomorphology, seismic reflection profiles and seismological data) have been used to develop images of the Gubbio fault, giving us the opportunity to compare different approaches and evaluate points of consensus and controversy in fault analysis and characterization. From our integrated analysis we define a well-focussed image of the geometry and kinematics of the Gubbio fault and the related Quaternary basin, while the seismogenic role of the fault is still ambiguous.

The Northern Apennines of Italy is a unique area to study active crustal processes due to the availability of high-resolution subsurface geology (deep borehole and seismic profiles) and seismicity (back-ground and seismic sequences) data. In this work we have investigated the relationship between crustal structures and lithologies, rheological profiles and seismicity cut-off by constructing three integrated profiles across the Umbria-Marche Apennines. At first approximation we observe a good correspondence between the background seismicity cut-off and the modelled brittle ductile transition (BDT): 90% of the seismic activity is located above the transition. In the area characterized by active extension, where the majority of the seismicity is occurring, most of the crustal earthquakes are confined within the brittle layer at depth Our work suggests that rheology and therefore the position of the brittle ductile transition exerts a role at regional scale for the occurrence of crustal seismicity, however crustal structures and lithology play the major role at a more local scale and therefore they need to be considered for a better understanding of earthquake distribution within the seismogenic layer.

Before seismic data were made available, the subsurface setting of the Umbria-Marche area was mainly derived from the extrapolation of surface data and from models resulting from analogies with other mountain chains around the world. During the 90s industrial seismic data availability considerably increased, allowing the definition of new, previously unknown features. Beside the industrial seismic data availability, a deep crustal, near vertical seismic section trending E-W was acquired (CROP-03) across the Italian peninsula from the Tyrrhenian to the Adriatic coast. The subsurface data defined the compressional deformation style (thin- Vs thick- skinned) and the extensional deformation style. A set of east-dipping low-angle-normal faults, which dissect the previous compressional structures and which are the dominant features controlling the extension of the Apennines were recognised. The subsequent application of the seismic data interpretation to seismotectonic issues, defined in more detail the subsurface geometries of the active faults and the relationships between upper crust structure and seismicity.