Central Apennines Research Articles

Bioclimatic pattern in a Mediterranean mountain area: assessment from a classification approach on a regional scale.

The present work analyses the main weather patterns over the period 1981-2010 in the Central Apennines (Italy), drawing upon data from 23 monitoring stations spanning a wide elevation range (260-1750 m asl). Cluster analysis was used to identify homogeneous units and to verify the effectiveness of the bioclimatic classification by crossing the results derived from the application of hierarchical and non-hierarchical classification techniques. The results reveal a diversified picture of five clusters that depends on several factors as elevation, the geographic position within or outside the mountainous range, and the regional morphological traits. Although Mediterranean and Temperate climatic features coexist, the Mediterranean pattern in the southern areas and internal valleys better expresses the overall mixed characteristics of Central Italy. The use of a mixed methodology of hierarchic and partitioning methods of cluster analysis improves the bioclimatic classification, especially to quantify the level of humidity and the mediterraneity degree.

The tectono-stratigraphic evolution of the Fucino Basin (central Apennines, Italy): new insights from the geological mapping of its north-eastern margin.

ABSTRACT We present the geological map of the north-eastern margin of the Fucino Basin, which is mainly characterized by Plio-Quaternary continental deposits that show transition from deeper-water lacustrine environment, marginal lacustrine system, and fluvial facies. These deposits unconformably overlie upper Messinian Lago-Mare sediments and pre-orogenic carbonate succession. The occurrence of Caspiocypris tiberina in the Plio-Quaternary lacustrine sediments, coupled with the normal magnetic polarity of Casa Colombaia section, led to suggest the onset of the sedimentation of these continental deposits to the late Piacenzian (2.58–3.04 Ma). The upper Messinian deposits are characterized by ostracod assemblages related to the Loxocorniculina djafarovi zone, pointing to the last Lago-Mare event of the Messinian Salinity Crisis (5.40–5.33 Ma). This new stratigraphic framework may be useful to refine the long-term slip rates of the still active normal faults that affect the north-eastern margin of the Fucino Basin.

Structural restoration and basin modelling of the central apennine orogen/foredeep/foreland system: New insights on the regional petroleum system

Basin modelling represents an important approach for the prediction of hydrocarbon generation/migration, identifying possible prospects and reducing the risk in exploration areas. This modelling can be also used to study the structural evolution of an area. Main input are the thermal/burial history of the sedimentary basin (key parameters for source rock maturity) and the adopted crustal model.We applied a basin modelling approach to the study of a portion of the Central Apennine orogen (Central Italy), where both thick-vs thin-skin interpretation models were historically proposed, and to the adjoining Central Adriatic foredeep/foreland system, to contribute reducing the tectonic and petroleum system uncertainties of this structurally complex area.We started from the available dataset obtained from the past hydrocarbon exploration activities, that resulted in several small/medium oil discoveries (evidence of an active petroleum system), making a structural review of the different crustal models proposed by the literature.We built two balanced 2D regional sections using MOVE software: one across the off-shore Central Adriatic foreland; and one from the front of the Central Apennine through the Central Adriatic foredeep/foreland system. This last section was modelled testing both a thick and a thin-skin structural scenario, implementing a structural restoration step using Dynel2D software. Using PetroMod2D we then compared the obtained petroleum system results to verify which structural scenario better fit with the present-day known distribution of hydrocarbon occurrences, both on-shore/off-shore. A 3D model was then implemented over key sectors to better understand the main hydrocarbon generation trends.Results suggest the thick-skin model as most suitable to justify the known hydrocarbon occurrences in the area. In addition, modelling indicates a lateral hydrocarbon migration as a key process for known hydrocarbon accumulation, active from the Upper Miocene (in the Central Apennine foredeep) and Upper Pliocene (in the Central Adriatic foreland) to present-day.

Understanding the Origin and Mixing of Deep Fluids in Shallow Aquifers and Possible Implications for Crustal Deformation Studies: San Vittorino Plain, Central Apennines

Expanding knowledge about the origin and mixing of deep fluids and the water–rock–gas interactions in aquifer systems can represent an improvement in the comprehension of crustal deformation processes. An analysis of the deep and meteoric fluid contributions to a regional groundwater circulation model in an active seismic area has been carried out. We performed two hydrogeochemical screenings of 15 springs in the San Vittorino Plain (central Italy). Furthermore, we updated the San Vittorino Plain structural setting with a new geological map and cross-sections, highlighting how and where the aquifers are intersected by faults. The application of Na-Li geothermometers, coupled with trace element and gas analyses, agrees in attributing the highest temperatures (>150 °C), the greatest enrichments in Li (124.3 ppb) and Cs (>5 ppb), and traces of mantle-derived He (1–2%) to springs located in correspondence with high-angle faults (i.e., S5, S11, S13, and S15). This evidence points out the role of faults acting as vehicles for deep fluids into regional carbonate aquifers. These results highlight the criteria for identifying the most suitable sites for monitoring variations in groundwater geochemistry due to the uprising of deep fluids modulated by fault activity to be further correlated with crustal deformation and possibly with seismicity.

Defining the Shallow Geothermal Heat-Exchange Potential for a Lower Fluvial Plain of the Central Apennines: The Metauro Valley (Marche Region, Italy)

In this work we assessed the shallow geothermal heat-exchange potential of a fluvial plain of the Central Apennines, the lower Metauro Valley, where about 90,000 people live. Publicly available geognostic drilling data from the Italian Seismic Microzonation studies have been exploited together with hydrogeological and thermophysical properties of the main geological formations of the area. These data have been averaged over the firsts 100 m of subsoil to define the thermal conductivity, the specific heat extraction rates of the ground and to establish the geothermal potential of the area (expressed in MWh y−1). The investigation revealed that the heat-exchange potential is mainly controlled by the bedrock lithotypes and the saturated conditions of the sedimentary infill. A general increase in thermal conductivity, specific heat extraction and geothermal potential have been mapped moving from the coast, where higher sedimentary infill thicknesses have been found, towards the inland where the carbonate bedrock approaches the surface. The geothermal potential of the investigated lower Metauro Valley is mostly between ~9.0 and ~10 MWh y−1 and the average depth to be drilled to supply a standard domestic power demand of 4.0 kW is ~96 m (ranging from 82 to 125 m all over the valley). This investigation emphasizes that the Seismic Microzonation studies represent a huge database to be exploited for the best assessment of the shallow geothermal potential throughout the Italian regions, which can be addressed by the implementation of heating and cooling through vertical closed-loop borehole heat exchanger systems coupled with geothermal heat pumps.

3D Discrete Fracture Network (DFN) models of damage zone fluid corridors within a reservoir-scale normal fault in carbonates: Multiscale approach using field data and UAV imagery

We combined structural data collected in the field and those obtained from a virtual outcrop model constructed from drone imagery, to perform Discrete Fracture Network (DFN) modelling and to characterize the fracture distribution within the damage zone of the low-displacement (~50 m) carbonate-hosted Pietrasecca Fault (PF) (central Apennines, Italy). Both in the hanging wall and in the footwall damage zones, fractures are vertical and parallel to slightly oblique to the fault strike. Fracture length distributions in the footwall damage zone indicate a high degree of fracture maturity, while in the hanging wall damage zone they indicate a low degree of fracture maturity. Pervasive stylolitization in the hanging wall must have hindered the development of through-going fractures, favoring diffuse fracturing characterized by stylolite-bounded fractures. DFN models suggest that permeabilities are 1–2 orders of magnitude greater in the footwall damage zone than in the hanging wall damage zone. As permeability (10−12 to 10−15 m2) is comparable with those measured in large-displacement (up to 600 m) faults in carbonates, our results show that also damage zones accompanying carbonate faults with ~50 m of displacement could be fracture corridors for efficient fluid flow within subsurface reservoirs. Therefore, we propose that jumps in subsurface permeabilities occurring in many carbonate fractured reservoirs could be associated with to the occurrence of high permeability fracture zones developed within damage zones of low-displacement faults. As the recent advancement in seismic imaging allow the recognition of faults with displacement in the order of a few tens of meters, reservoir geologists and engineers can apply results of this study to better model the subsurface flow pathways near low displacement faults in carbonate reservoirs.

Nephrolepidina and unispiralled Miogypsinidae from the Oligo-Miocene toe-of-slope succession of Gran Sasso (L'Aquila, Central Apennines - Italy): biometric and evolutionary remarks

A biometric analysis was performed on twelve Nephrolepidina and ten Miogypsina and Miogypsinoides populations, coming from the Tre Valloni section, an Oligo-Miocene calcarenitic toe-of-slope succession outcropping in the southern sector of Gran Sasso (L'Aquila, Central Apennines - Italy). Miogypsina populations are investigated applying two essential parameters, i.e., the number of the nepionic chambers and the protoconch diameter. Previously detected evidences of reworking in the same material suggested to use some cautions to avoid misleading results. A mixed typological-statistical methodology is used, leading from starting "disordered" assemblages to final "virtual but reliable" populations, cleaned up from reworked specimens, in order to implement the accuracy of the biostratigraphic results. This goal is reached for the lower part of the succession only. According to the biometric limits proposed for the various chronospecies in the recent literature, the resulting populations are referred to Miogypsinoides ex. interc. complanatus-formosensis up to Md. bantamensis, and to Miogypsina basraensis up to M. ex. interc. gunteri-tani. This sequence of taxa, in general, is in agreement with the principle of nepionic acceleration, with a progressive reduction in the average number of nepionic chambers (X), arranged in a single spiral, just peculiar in the more primitive populations. Miogypsinoides bantamensis and Miogypsina basraensis are recognized biometrically for the first time in the Central Apennines. Nephrolepidina populations are investigated applying the recently introduced biometry of the fifth stage of the neanic equatorial chamberlets, supplying additional data about parameters and factors that had already demonstrated to have taxonomic-biostratigraphic significance. The biometric analysis of the embryo-nepionic stages was performed as an integration of the data obtained in a previous study, excluding the uppermost samples in which Nephrolepidina is clearly reworked, being characterized by primitive morphology, i.e., almost isolepidine embryo, few adauxiliary chamberlets, and ogival equatorial chamberlets. The neanic data evidence that the "Degree of stolonic distalization" (Factor FD5) and the "Shape Index" (Factor SI5), at the 5th nepionic stage of the population have a very good fitting with the previously evidenced Neanic acceleration, as the overall trend to modify the shape of the equatorial chambers, connected with a gradually more distal position of the radial stolons. Unispiralled Miogypsina, associated with Nephrolepidina at an advanced evolutionary stage, suggest a continuous reworking of primitive miogypsinids, without an involvement of more evolute bispiralled forms. The biostratigraphic assessment of the Venacquaro and Glauconitic Calcarenite formations is improved, assigning the Venacquaro Formation to the Chattian-lowermost Aquitanian (SBZ22B-basal SBZ24) and the base of the Glauconitic Calcatenite to the Aquitanian (SBZ24 p. p.). The investigated sedimentary succession was deposited along a slope to toe of slope characterized by a mixture of taxa displaced from shallow-water environments and reworked primitive specimens eroded along channels.

Seismic modelling of outcrop carbonate systems: an application to the Cretaceous platform-to-basin system of the Maiella Mountain (central Apennines, Italy)

Abstract Forward seismic models of outcrop analogues are used in hydrocarbon exploration to generate more coherent geological–geophysical models that provide an important scale link between outcrops and seismic survey data. Exploration within slope carbonate plays can be problematic with uncertainties about the reservoir geometries, distribution and volumes owing to complex seismic imaging and lack of closely spaced wells. This seismic modelling study provides a synthetic seismic characterization of the carbonate platform-to-slope-to-basin transition exposed across the Maiella Mountain, central Italy. This outcrop represents an analogue for exploration in carbonate slope strata in the Adriatic offshore area. Integration of original and previously published data allows 2D and 3D geological modelling, providing a better characterization of relationships between the palaeoescarpment and resedimented deposits. The seismic response of the various geological features of this transitional carbonate system is simulated via synthetic seismic modelling using innovative, modern techniques. The seismic simulation was performed in both post-stack-time- and pre-stack-depth-migrated domains. These synthetic seismic models help in understanding and predicting the seismic architecture and character of the palaeoescarpment and resedimented slope deposits.

Seed germination reports for Policy species in the central Apennines

Seed germination reports for Policy species in the central Apennines

Investigation of the Luco Dei Marsi DSGSD Revealing the First Evidence of a Basal Shear Zone in the Central Apennine Belt (Italy)

Investigation of the Luco Dei Marsi DSGSD Revealing the First Evidence of a Basal Shear Zone in the Central Apennine Belt (Italy)

Application of an ensemble earthquake rate model in Italy, considering seismic catalogs and fault moment release

We develop an ensemble earthquake rate model that provides spatially variable time-independent (Poisson) long-term annual occurrence rates of seismic events throughout Italy, for magnitude bin of 0.1 units from Mw ≥ 4.5 in spatial cells of 0.1° × 0.1°. We weighed seismic activity rates of smoothed seismicity and fault-based inputs to build our earthquake rupture forecast model, merging it into a single ensemble model. Both inputs adopt a tapered Gutenberg-Richter relation with a single b-value and a single corner magnitude estimated by earthquakes catalog. The spatial smoothed seismicity was obtained using the classical kernel smoothing method with the inclusion of magnitude dependent completeness periods applied to the Historical (CPTI15) and Instrumental seismic catalogs. For each seismogenic source provided by the Database of the Individual Seismogenic Sources (DISS), we computed the annual rate of the events above Mw 4.5, assuming that the seismic moments of the earthquakes generated by each fault are distributed according to the tapered Gutenberg-Richter relation with the same parameters of the smoothed seismicity models. Comparing seismic annual rates of the catalogs with those of the seismogenic sources, we realized that there is a good agreement between these rates in Central Apennines zones, whereas the seismogenic rates are higher than those of the catalogs in the north east and south of Italy. We also tested our model against the strong Italian earthquakes (Mw 5.5+), in order to check if the total number (N-test) and the spatial distribution (S-test) of these events was compatible with our model, obtaining good results, i.e. high p-values in the test. The final model will be a branch of the new Italian seismic hazard map.

The Monterey Event in the Mediterranean platform to basin transition: The Guadagnolo Formation (Miocene, Prenestini Mountains, Central Apennines)

The stratigraphic evolution of the Guadagnolo Fm, developed on the transition between the Latium-Abruzzi Platform and the Umbria Sabina Basin (central Apennines), was studied through facies and stable isotope analysis. Calcareous nannofossil biostratigraphy allows to identify the Burdigalian-Langhian boundary, constraining the sections to the lower to middle Miocene. This interval consists of marly deposits forming the intermediate member of the formation dominated by sponge spicules, molluscs, bryozoans, benthic and planktonic foraminifers. This member is deposited in a distal outer ramp where the abundance of siliceous sponges has been attributed to the high seawater fertility coinciding with the Monterey event, enhanced by regional nutrient flux due to continental runoff and volcanism. The upper member is Serravallian and consists of bryozoan-dominated cross-bedded calcarenites deposited in a shallower environment of the outer ramp.A positive carbon isotope excursion was correlated with the Monterey event recorded in the Central Apennines carbonate ramps and from ODP sites. Five carbon maxima belonging to the Monterey Carbon Isotope Excursion have been identified. Four carbon isotope peaks fall in the spongolitic member, one in the upper member. The Carbon Maxima recorded within the spongolitic member show an attenuate isotope excursion compared with the pelagic and the carbonate platforms record. The weaker signal is due to the fractionation effect of primary producers of the photic zone and to the sponge release of 12C-enriched CO2 deriving from the oxidation of organic matter. Conversely, the largest positive carbon isotope excursion is recorded in the upper member, representative of a shallower environment, and it is due to the absence of sponges and the increased contribution of photosynthetic biota. The shoaling of the depositional environment is related to the global cooling recorded after 14 Ma, as evident also from the δ18O positive shift at the base of the upper member of the Guadagnolo Fm.

Geological map of the Mt. Vettoretto–Capodacqua area (Central Apennines, Italy) and cross-cutting relationships between Sibillini Mts. Thrust and Mt. Vettore normal faults system

We present the results of a geological mapping project performed in the southern portion of the Sibillini Mts., aimed at defining the structural relationships between the Sibillini Mts. Thrust front and the Mt. Vettore normal fault system, reactivated during the 2016-2017 central Italy seismic sequence. The Sibillini Mts. Thrust is characterised by a hanging wall where the Meso-Cenozoic Umbria-Marche succession crops out, while the footwall is represented by the Messinian Laga foredeep unit. The Mt. Vettore extensional fault system is formed by two main normal faults, the Castelluccio Plain and Mt. Vettoretto faults. Being the cross-cutting relationships between the structural elements hidden by a thick debris cover, they have been reconstructed analyzing the geometries of the hanging wall anticline of the Sibillini Mts. Thrust and other field constrains. This allowed us to conclude that the Sibillini Mts. Thrust was displaced by the Castelluccio Plain normal fault with a max throw of ~ 250 m. Both the Castelluccio Plain normal fault and the Sibillini Mts. Thrust are subsequently cut by the Mt. Vettoretto fault, which is inferred to reuse in part the inverted Sibillini Mts. Thrust plane.

The submarine dune field of the Bolognano Fm: depositional processes and the carbonate reservoir potential (Chattian to Burdigalian, Majella Carbonate Platform)

This two-days field trip is focused on the Bolognano Formation, the homoclinal carbonate ramp developed on the Majella Mountain (Central Apennines) from the late Rupelian to the Messinian. The northern sectors of the Majella Mountain show excellent and continuous exposures of this carbonate ramp. In the late Oligocene- early Miocene, the paleoceanography of the Mediterranean was controlled by different seaways, one of the largest being the proto-Adriatic basin, bounded by the Apulian carbonate platform and by the Dinaride coast. In this context, a strong northward current led to the development of submarine dunes during the Chattian and the Burdigalian. In this fieldtrip, we discuss the relationships among sedimentary structures and depositional processes, stratigraphic architecture and syn/post-depositional tectonics. Furthermore, the lower Miocene cross-bedded calcarenites of the Bolognano Fm identify an important reservoir rock. In the last two stops, the bitumen shows are analysed and the possible controlling factors of migration and trapping are discussed. The comparison between bitumen-filled fractured and unfractured rocks allows detecting the controlling factors on the migration of the hydrocarbons and its relationship with tectonics. The high primary porosity and the lateral continuity of the calcarenites are identified as the main controlling factor on the hydrocarbon migration.

Three-dimensional numerical simulation of the interseismic and coseismic phases associated with the 6 April 2009, Mw 6.3 L'Aquila earthquake (Central Italy)

Although several observations have been reported in the literature before a strong earthquake, their relation with the forthcoming event is often controversial. Since many physical processes and parameters govern the dynamics of preparation, initiation, and occurrence of earthquakes, their understanding is essential for explaining anomalous seismological, geophysical, hydrological and geodetic signals before a strong earthquake that may be considered for seismic monitoring and hazard assessment.In this work, the interseismic and coseismic stress and strain fields associated with the 6 April 2009, Mw 6.3 L'Aquila earthquake are calculated via a 3D numerical model designed to simulate the crustal interseismic loading and the coseismic brittle episodic dislocation along the fault. The model adopts a framework of gravitational and tectonic forces that are compatible with the geodynamics of the Central Apennines region of the Italian territory. The model assumes a brittle upper crust, where the fault has stick-slip behaviour, and a plastic deeper crust, where the fault is in stationary creep.The results indicate that the concurrent action of gravitational and tectonic forces determines steep interseismic stress gradients at the transition between the creeping and locked fault planes that promote the coseismic subsidence of the hanging wall. The interseismic strain above the transition between that locked upper fault and its unlocked lower shear zone develops a dilated volume in the hanging wall and a contracted volume in the footwall. These stress and strain variations are compatible with seismological, geophysical and geodetic anomalies observed before the earthquake, i.e., Vp/Vs anomalies and location of foreshocks. Interseismic stress and strain patterns invert during the coseismic stage. The dilated volume, formed during the interseismic phase, will be contracted at the coseismic stage and, conversely, the footwall volume previously contracted will be expanded.

HydroQuakes, central Apennines, Italy: Towards a hydrogeochemical monitoring network for seismic precursors and the hydro-seismo-sensitivity of boron

Hydrogeochemical changes before Mw ≥ ∼5.0 earthquakes are hoped to be applicable as seismic precursors. It is now necessary to pass from single experiences to structured networks, systematically monitoring large seismic areas for long periods. Our aim is to provide a pilot methodological experience for how such networks could be realized and the types of results they could deliver. We present the method and some initial results to document the method’s applicability. In 2017, we started the HydroQuakes project in seismically active central Italy, with the Sulmona and Matese areas selected as the two monitoring nodes. Each node includes 5–6 monitored springs, and for each spring, we performed laboratory analyses of major and trace elements and some isotopes. We installed in situ probes for continuous monitoring. Between December 2017 and January 2020, the most energetic earthquakes were three events with Mw of 3.9, 4.1, and 4.4. They were not preceded by significant hydrogeochemical anomalies, except for the Mw 4.1 event. Despite its low Mw, this earthquake occurred over a large normal fault at a great depth in the crust (∼17 km) and was preceded by weak but detectable hydrogeochemical anomalies of boron and δ11B that were similar but milder than the hydrogeochemical anomalies before the 2016 Mw 6.0 earthquake in the central Apennines. This and previous evidence show the B and δ11B hydro-seismo-sensitivity and indicates that pre-seismic hydrogeochemical anomalies could arise mostly before Mw ≥ ∼5.0 earthquakes, with weak exceptions occurring in specific conditions such as long and deep faults.

Earthquake-Related Signals in Central Italy Detected by Hydrogeochemical and Satellite Techniques

Central Apennines are one of the regions of highest seismic risk of Italy. A number of energetic events (M_W > 5) hit the region during the period 2004-2017, killing several hundreds of people (e.g., 294 casualties associated with the August 24th, 2016, M_W 6.0 event of Amatrice). These earthquakes impacted piezometric levels, springs discharge, and groundwater chemistry on a large area, even at distances of several tens of kilometers from the epicenters. Here we present a multidisciplinary dataset based on hydrogeochemical and satellite observations associated with the seismic events occurred in Central Italy during the period 2004-2017, that combines information derived from the application of groundwater monitoring and satellite techniques. Groundwater monitoring techniques allowed to detect hydrogeochemical anomalies in spring and well waters (20 sampling points over the observation period), whereas satellite techniques were applied to detect time-space variations in ground thermal emissions. We detected two significant, almost synchronous, anomalies in 2009 and 2016-2017 with both techniques, and we tentatively correlated them to crustal deformation processes. Part of the observed signals was detected before mainshocks, and they appear to be related to aseismic slip or to seismic slip eventually induced by minor fluctuations in seismicity. We argued that the combination of two factors, i.e., the shallow depth of local earthquakes and the concurrent deepening of groundwater circulation paths to several km depth, allowed for the recording of variations in the stress field by geofluids released at the surface.

Seismically Induced Snow Avalanches: The Central Italy Case

Snow avalanches are critical events due to the sudden instability of snow in mountain regions. Seismically induced snow avalanches, due to a particular type of trigger perturbing snow-covered slopes, are occasional events in geodynamically active mountain regions around the world, which can lead to large anomalous avalanches. The seismic trigger of an avalanche is either simultaneous or delayed. In Italy, the Alps, and particularly the Apennines, feature large areas expected to be affected by seismically induced snow avalanches. In this work, the avalanches’ distribution in Central Italy (i.e., Abruzzo region) and its connection with moderate–high seismicity were investigated. With regional and historical analyses, we investigated the connection between avalanches and seismicity. We revealed two main events of seismically induced avalanches (6–9 April 2009, western Gran Sasso-Assergi area, and 18 January 2017, Gran Sasso massif) characterized by an anomalous distribution of avalanches. A specific and detailed analysis focused on the northeast Mt. Siella slope, where well-documented and constrained events occurred on 18 January 2017 in the Gran Sasso area, affecting a tourist facility. This involves geomorphological and photogeological multitemporal investigations. Moreover, the Rigopiano avalanche was analyzed through 3D numerical modelling and stability analysis of the snow to investigate the possible seismic trigger. We found the avalanche was consistent with delayed seismically induced avalanche cases. This combination contributed to a more general assessment of the seismically induced avalanches in the Central Apennines area (i.e., Abruzzo region) and provided new examples of seismically induced avalanches at both the regional and detailed scales, which are largely consistent with the world distribution.

Seismicity Rate Changes and Geodetic Transients in Central Apennines

AbstractUsing template matching and GPS data, we investigate the evolution of seismicity and observable deformation in Central Apennines. Seismicity appears more persistent at the base of the seismogenic layer than in the shallower crust. Diffuse activity is reported on segments at depth, alternating along strike with apparent quiescence on segments that experienced one or more Mw6+ earthquakes in 1997, 2009, and 2016. Central Apennines are likely underlain by a sizeable shear zone with areas of diffuse seismicity bounding shallow normal faults where Mw6+ earthquakes occurred. The deformation observed at the surface seems to follow the seismicity variations at the base of seismogenic layer along the Apenninic chain. Principal and independent component analyses of GPS data exhibit a transient when the 2016 foreshock sequence starts. This transient propagated northward from the Campotosto fault up to the Alto Tiberina fault system and has likely loaded the Mw6+ 2016 earthquake sequence.

Redescription of Monacha pantanellii (De Stefani, 1879), a species endemic to the central Apennines, Italy (Gastropoda, Eupulmonata, Hygromiidae) by an integrative molecular and morphological approach.

Specimens obtained from ten populations of a Monacha species from the central Apennines were compared with six molecular lineages of Monacha cantiana s. l. (CAN-1, CAN-2, CAN-3, CAN-4, CAN-5, CAN-6) and two other Monacha species (M. cartusiana and M. parumcincta), treated as outgroup, by molecular (nucleotide sequences of two mitochondrial COI and 16S rDNA as well as two nuclear ITS2 and H3 gene fragments) and morphological (shell and genital anatomy) analysis. The results strongly suggest that these populations represent a separate species for which two names are available: the older Helix pantanellii De Stefani, 1879 and the junior M. ruffoi Giusti, 1973. The nucleotide sequences created well separated clades on each phylogenetic tree. Genital anatomy included several distinctive features concerning vaginal appendix, penis, penial papilla and flagellum; instead, shell characters only enabled them to be distinguished from M. cartusiana and M. parumcincta. Remarkably, populations of M. pantanellii show high morphological variability. Shell variability mainly concerns size, some populations having very small dimensions. Genital variability shows a more intricate pattern of all anatomical parts, being higher as regards the vagina and vaginal appendix. Despite this morphological variability, the K2P distance range of COI sequences between populations is narrow (0.2–4.5%), if we consider all but three of the 53 sequences obtained. This research confirmed that the species of Monacha and their molecularly distinguished lineages can only occasionally be recognised morphologically and that they have significant inter- and intra-population variability. The possibility of using an overall approach, including shell, genital and molecular evidence, was taken in order to establish a reliable taxonomic setting.