The Apennine orogenic system is a natural laboratory for multidisciplinary and integrated studies. The evolution of the Apennines is framed by the fragmentation of Pangea and the development of the ...Tyrrhenian Basin. Thus, the Apennines have carried this memory from the Permian and Triassic–Early Jurassic rifting, to the Oligocene–Miocene collision, and finally to the Miocene–Present, during which extension and compression have progressively migrated eastwards. Magmatism, hydrothermalism, and sedimentation in the Apennines have accordingly evolved in time and space. In this Special Issue, multidisciplinary and integrated studies have been published improving our knowledge of the Apennines and discussing: (a) the development of deformation and metamorphism in different tectonic environments, from the rifting stage to the subduction, exhumation, and late-orogenic stages; (b) the Meso-Cenozoic tectono-stratigraphic evolution of sedimentary basins, and their role in the Apennine orogeny; (c) the thermochronological evolution of sedimentary units and the dating of deformation episodes through geochemical techniques; (d) the magmatism and its connection to geodynamic evolution, from the mountain chain to the Tyrrhenian Basin; (e) recent tectonics, as reconstructed through seismological and paleo-seismological studies; and (f) the crustal structure, as derived by geophysical methods and their interpretation.
Earthquake early warning (EEW) systems are required to report earthquake locations and magnitudes as quickly as possible before the damaging S wave arrival to mitigate seismic hazards. Deep learning ...techniques provide potential for extracting earthquake source information from full seismic waveforms instead of seismic phase picks. We developed a novel deep learning EEW system that utilizes fully convolutional networks to simultaneously detect earthquakes and estimate their source parameters from continuous seismic waveform streams. The system determines earthquake location and magnitude as soon as very few stations receive earthquake signals and evolutionarily improves the solutions by receiving continuous data. We apply the system to the 2016 M 6.0 Central Apennines, Italy Earthquake and its first‐week aftershocks. Earthquake locations and magnitudes can be reliably determined as early as 4 s after the earliest P phase, with mean error ranges of 8.5–4.7 km and 0.33–0.27, respectively.
Plain Language Summary
Earthquake early warning (EEW) systems detect hazardous earthquakes, estimate their source parameters, and transmit warnings to the public. Conventional EEW algorithms depend on picking and analyzing the first seismic compressional wave (i.e., P wave). Seismic waveforms contain more information and can potentially be used to estimate earthquake source parameters with the fewest possible number of stations and to promptly transmit warning information. Deep learning techniques provide opportunities for extracting and exploiting the features behind seismic waveforms. In this study, we develop a fully automatic real‐time EEW system by directly mapping seismic waveform data to earthquake source parameters using deep learning techniques. We apply this system to the 2016 M 6.0 Central Apennines, Italy Earthquake and its first‐week aftershocks. Our results show EEW can be reliably issued as early as 4 s after the earliest P arrival.
Key Points
A fully convolutional network is designed for real‐time earthquake detection, location, and magnitude estimation
Earthquake locations and magnitudes can be determined as early as a few seconds of earthquake signals received at very few stations
The system evolutionarily improves and updates earthquake source parameters by receiving continuous data
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Abstract
Many recent studies have investigated the replacive formation of troctolites from mantle protoliths and the compositional evolution of the percolating melt during melt–rock interaction ...processes. However, strong structural and geochemical constraints for a replacive origin have not yet been established. The Erro–Tobbio impregnated mantle peridotites are primarily associated with a hectometre-size troctolitic body and crosscutting gabbroic dykes, providing a good field control on melt–rock interaction processes and subsequent magmatic intrusions. The troctolitic body exhibits high inner complexity, with a host troctolite (Troctolite A) crosscut by a second generation of troctolitic metre-size pseudo-tabular bodies (Troctolite B). The host Troctolite A is characterized by two different textural types of olivine, corroded deformed millimetre- to centimetre-size olivine and fine-grained rounded undeformed olivine, both embedded in interstitial to poikilitic plagioclase and clinopyroxene. Troctolite A shows melt–rock reaction microstructures indicative of replacive formation after percolation and impregnation of mantle dunites by a reactive melt. The evolution of the texture and crystallographic preferred orientation (CPO) of olivine are correlated and depend on the melt/rock ratio involved in the impregnation process. A low melt/rock ratio allows the preservation of the protolith structure, whereas a high melt/rock ratio leads to the disaggregation of the pre-existing matrix. The mineral compositions in Troctolite A define reactive trends, indicative of the buffering of the melt composition by assimilation of olivine during impregnation. The magmatic Troctolite B bodies are intruded within the pre-existing Troctolite A and are characterized by extreme textural variations of olivine, from decimetre-size dendritic to fine-grained euhedral crystals embedded in poikilitic plagioclase. This textural variability is the result of olivine assimilation during melt–rock reaction and the correlated increase in the degree of undercooling of the percolating melt. In the late gabbroic intrusions, mineral compositions are consistent with the fractional crystallization of melts modified after the reactive crystallization of Troctolites A and B. The Erro–Tobbio troctolitic body has a multi-stage origin, marked by the transition from reactive to fractional crystallization and diffuse to focused melt percolation and intrusion, related to progressive exhumation. During the formation of the troctolitic body, the melt composition was modified and controlled by assimilation and concomitant crystallization reactions occurring at low melt supply. Similar processes have been described in ultraslow-spreading oceanic settings characterized by scarce magmatic activity.
Rivers and effluents have been identified as major pathways for microplastics of terrestrial sources. Moreover, lakes of different dimensions and even in remote locations contain microplastics in ...striking abundances. This study investigates concentrations of microplastic particles at two lakes in central Italy (Lake Bolsena, Lake Chiusi). A total number of six Manta Trawls have been carried out, two of them one day after heavy winds occurred on Lake Bolsena showing effects on particle distribution of fragments and fibers of varying size categories. Additionally, 36 sediment samples from lakeshores were analyzed for microplastic content. In the surface waters 2.68 to 3.36 particles/m3 (Lake Chiusi) and 0.82 to 4.42 particles/m3 (Lake Bolsena) were detected, respectively. Main differences between the lakes are attributed to lake characteristics such as surface and catchment area, depth and the presence of local wind patterns and tide range at Lake Bolsena. An event of heavy winds and moderate rainfall prior to one sampling led to an increase of concentrations at Lake Bolsena which is most probable related to lateral land-based and sewage effluent inputs. The abundances of microplastic particles in sediments vary from mean values of 112 (Lake Bolsena) to 234 particles/kg dry weight (Lake Chiusi). Lake Chiusi results reveal elevated fiber concentrations compared to those of Lake Bolsena what might be a result of higher organic content and a shift in grain size distribution towards the silt and clay fraction at the shallow and highly eutrophic Lake Chiusi. The distribution of particles along different beach levels revealed no significant differences.
•First evidence on significant microplastic pollution of lakes in central Italy.•Heavy winds influence microplastic abundance in the surface water layer.•Redistribution of heavy wind affects fragments but not fibers.•Contamination of lakeshore sediment and repository is a factor of silt and clay content.
This paper presents the first data on significant microplastic pollution of surface waters and shoreline sediments of lakes in central Italy taking into account the influence of wind-driven distribution of particles.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•Interseismic GPS velocity field for monitoring of the Apennine.•The extension rate does not follow the topographic height of the Apennine.•A tensile source has been modelled for the 29 December 2013 ...earthquake.•Sharing of the SAGnet GPS archive.
We investigated the interseismic GPS velocity field across the transition zone between Central and Southern Apennine comprising the Meta–Mainarde-Venafro and Alto Molise–Sannio-Matese mounts. The kinematic field obtained by combining GPS network solutions is based on data collected by the unpublished episodic campaigns carried out on Southern Apennine Geodetic network (SAGNet from 2000 to 2013), IGM95 network (Giuliani et al., 2009 from 1994 to 2007) and continuous GPS stations. The data collected after the 29 December 2013 earthquake (Mw 5.0) until early 2014 allowed estimating displacements at 15 SAGNet stations.
The extension rate computed across the Matese massif along an anti-Apennine profile is 2.0±0.2 mm/yr. The interseismic velocities projected along the profile show that the maximum extension does not follow the topographic high of the Apennines but is shifted toward the eastern outer belt. No significant GPS deformation corresponding to inner faults systems of the Matese massif is detected.
Taking into account our results and other geophysical data, we propose a conceptual model, which identifies the 2013–2014 seismic sequence as not due to an extensional deformation style usual along the Apennine chain. In fact, we have measured too large “coseismic” displacements, that could be explained as the result of tectonic regional stress, CO2-rich fluid migration and elastic loading of water in the karst Matese massif. We recognized a tensile source as model of dislocation of 2013–2014 earthquakes. It represents a simplification of a main fault system and fracture zone affecting the Matese massif. The dislocation along NE-dipping North Matese Fault System (NMFS) could be the driving mechanism of the recent seismic sequences.
Moreover, to the first time the SAGnet GPS data collected from 1994 to 2014, are share and available to the scientific community in the open access data archive.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The Neogene and Quaternary tectonic evolution of the inner Northern Apennines (i.e southern Tuscany and northern Tyrrhenian Sea), as well as its crustal features (i.e. low crustal thickness, ...Neogene-Quaternary magmatism, widespread geothermal anomalies, lateral segmentation of the stacked tectonic units, extensive deep sedimentary basins), are framed in different geodynamic scenarios: compressional, extensional or both, pulsing. Consequently, the basin and range structure that characterises the northern Tyrrhenian Sea and southern Tuscany is considered as a consequence of (i) out-of-sequence thrusts and related thrust-top-basins, (ii) polyphased normal faulting that formed horst and graben structures or (iii) a combination of both. This paper provides a new dataset from a sector of the eastern inner Northern Apennines (i.e. Monti del Chianti - Monte Cetona ridge) contributing to this scientific debate. New fieldwork and structural analysis carried out in selected areas along the ridge allowed to define the chronology of the main tectonic events on the basis of their influence on the marine and continental sedimentation. The dataset supports for early Miocene - (?) Serravallian in-sequence and out-of-sequence thrusting. Thrusting produced complex staking patterns of Tuscan and Ligurian Units. Extensional detachments developed since later middle Miocene and controlled the Neogene sedimentation in bowl-shaped structural depressions, later dissected by normal faults enhancing the accommodation space for Pliocene marine deposits in broad NNW-trending basins (Siena-Radicofani and Valdichiana Basins). In this perspective, no data supports for active, continuous or pulsing, compressional tectonics after late Serravalian. As a result, in the whole inland inner Northern Apennines the extensional tectonics was continuously active at least since middle Miocene and controlled the basins development, magmatism and structure of the crust and lithosphere.
•The study area was affected by a continuous extensional tectonics since Late Serravallian.•The eastern margin of the Monti del Chianti-Monte Cetona ridge is the front of an Middle Miocene out-of-sequence thrust.•The Monti del Chianti-Monte Cetona ridge is a Zanclean-Piacenzian horst.•Syn-tectonic Tortonian-Messinian sediments deposited in thinned crustal sectors by extensional detachments.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Large seismic sequences in Italy are confined at depth by basement rocks.•Basement with shear along networks of phyllosilicates surrounding quartz lenses.•Low friction and rate-strengthening of ...phyllosilicates dictate shear zone rheology.•Aseismic slip along phyllosilicates limits the depth of the seismogenic zone.
Crustal seismicity is in general confined within the seismogenic layer, which is bounded at depth by processes related to the brittle-ductile transition (BDT) and in the shallow region by fault zone consolidation state and mineralogy. In the past 10-15 years, high resolution seismological and geodetic data have shown that faulting within and around the traditional seismogenic zone occurs in a large variety of slip modes. Frictional and structural heterogeneities have been invoked to explain such differences in fault slip mode and behaviour. However, an integrated and comprehensive picture remains extremely challenging because of difficulties to properly characterize fault rocks at seismogenic depths. Thus, the central-northern Apennines provide a unique opportunity because of the integration of deep-borehole stratigraphy and seismic reflection profiles with high resolution seismological data and outcrop studies. These works show that seismic sequences are limited within the sedimentary cover (depth < 9-10 km), suggesting that the underlaying basement plays a key-role in dictating the lower boundary of the seismogenic zone.
Here we integrate structural data on exhumed outcrops of basement rocks with laboratory friction data to shed light on the mechanics of the Apenninic basement. Structural data highlight heterogeneous and pervasive deformation where foliated and phyllosilicate-rich rocks surround more competent quartz-rich lenses up to hundreds of meters in thickness. Phyllosilicate horizons deform predominantly by folding and foliation-parallel frictional sliding whereas quartz-rich lenses are characterized by brittle signatures represented by extensive fracturing and minor faulting. Laboratory experiments revealed that quartz-rich lithologies have relatively high friction, μ≈0.51, velocity-strengthening to neutral behaviour, and elevated healing rates. On the contrary, phyllosilicate-rich (muscovite and chlorite) lithologies show low friction, 0.23 <μ < 0.31, a marked velocity strengthening behaviour that increases with increasing sliding velocity and negligible rates of frictional healing.
Our integrated approach suggests that in the Apenninic basement deformation occurs along shear zones distributed on thickness up-to several kilometres, where the frictionally stable, foliated, and phyllosilicate-rich horizons favour aseismic deformation and therefore confine the depth of major earthquake ruptures and the seismogenic zone.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Detrital geochronology studies require a careful quantification of hydraulic sorting effects and of the variable abundance (fertility) of datable minerals in different parent rocks. Because the ...physical processes of settling and selective entrainment are well known, their effects in sediments can be easily detected and modeled mathematically. By contrast, mineral fertility in parent rocks depends on their full geological history. As a consequence, the relationships between bedrock geology and mineral fertility are hardly predictable, and a direct measurement of this latter parameter is thus required. In this review article, we describe the basic principles of hydraulic sorting, and illustrate a quantitative approach for mineral fertility determination that applies these basic principles to the analysis of modern sediments. Its application to the European Alps shows that apatite and zircon fertility values may range over three orders of magnitude. Variable mineral fertility in parent rocks thus represents, by far, the largest source of bias in detrital geochronology studies. Our study highlights an evident relationship between bedrock geology and mineral fertility, which confirms that the mineral concentration in modern sediments, in the lack of hydraulic sorting effects, is a good proxy of the mineral abundance in bedrock. Mineral fertility maps of the European Alps unravel that metamorphic and plutonic rocks generally have higher apatite and zircon fertility values than sedimentary rocks, but major variations are also observed between different tectonic units within the same paleogeographic domain. The impact of mineral fertility in detrital studies is eventually illustrated with examples from the Alpine region, based on alternative sampling strategies (i.e., the confluence sampling and the along-trunk sampling approaches). We show that geological interpretations are strongly improved when mineral fertility is properly taken into account, not only in modern settings, but also in ancient sedimentary successions.
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•Basic principles to test hydraulic sorting effects in detrital geochronology studies•A quantitative approach for routine mineral fertility determination in source rocks•Variable mineral fertility is the major source of bias in detrital geochronology.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The multideformed axial zone of the Apennines provides a great opportunity to explore the influence of pre-existing cross-structures (inherited from pre-Quaternary tectonic phases) on the ...segmentation of Quaternary/active seismogenic extensional faults. Detailed geological and structural data and their comparison with seismological data show that although the attitudes (strike and dip) of oblique pre-existing faults are certainly an important factor in determining a segment boundary, the size of the inherited oblique structures seems to be more crucial. Pre-existing cross-structures with lengths ranging from several kilometers to a few tens of kilometers show a twofold behavior. They can act as segment barriers during the rupture of a single fault segment or they can be reactivated as transfer zones inducing the activation of two adjacent segments that belong to the same fault system. Regional basement/crustal oblique pre-existing cross-structures, with lengths ranging from several tens of kilometers to hundreds of kilometers (commonly NNE-striking), may act as “persistent structural barriers” that halt both fault segment and fault system propagation, thus determining their terminations and maximum sizes. In the northern-central Apennines, the NNE-striking Ancona–Anzio, Valnerina, and Ortona–Roccamonfina tectonic lineaments, although having been repeatedly reactivated since the Mesozoic, represent the most important examples of these structures. Moreover, probably due to their misorientation with respect to the present extensional stress field, regional NNE-striking pre-existing structures appear to be less likely to produce strong magnitude events (no surface evidence for Quaternary faulting has been found thus far and historical and instrumental seismicity shows only
M
<
6 events).
M ~
7 event, on the other hand, is more likely to occur along the (N)NW–(S)SE trending normal fault systems. Lastly, we propose a model that can explain the different sizes of fault segments and fault systems on the basis of their location with respect to the “persistent structural barriers” and their spacing. In this view, our results may contribute to a more reasonable assessment of the nature and size of future surface ruptures in the northern-central Apennines, which are of critical importance to estimating seismic hazard.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•A multi-scale diachronous-synchronous approach is used.•Land-use changes at both reach and basin scales drove adjustment in Italian rivers.•Southern rivers do not undergo floodplain afforestation, ...although they narrowed.•Similarities and differences between Italian and French river evolutions are found.•Geomorphic diagnosis must consider land-use change effects on river adjustments.
For eight rivers situated from northern to southern Italy, the evolutionary trajectories since the middle 19th century and the key controlling factors of channel adjustments were reconstructed using a combined diachronous-synchronous approach, integrating data from catchment- to reach-scale. The analysis takes advantage of multi-temporal GIS analysis of maps, aerial photographs, and orthophotos, and data from literature, archives, and official surveys of population and agrarian censuses. The main aims were to link historical channel responses to human and climate disturbances evidencing regional scale similarities and dissimilarities and to explain the role of upland and floodplain land use changes in the interpretation of channel adjustments.
From the middle 19th century to the 1950s, both channel widening and narrowing were observed. These processes were related to land use disturbances (e.g., afforestation versus deforestation) acting at both reach and catchment scales. From the 1950s to 1970s, channel narrowing in some rivers accelerated simultaneously with forests encroachment on fluvial corridors and human abandonment of intense floodplain uses, before the action of any other factors. In southern Italian rivers, channel adjustments were more intense and occurred later than in northern ones, but they remained more active once adjustment ended. Even though these rivers underwent a rural decline, their floodplains were little colonized by mature forests, probably because of drier climatic conditions exacerbated by dewatering due to channel incision. This also means that upland afforestation, with its effects on bedload delivery, was a more critical driver in controlling narrowing than floodplain afforestation, as in this southern context we do not observe floodplain afforestation but grazing expansion. When forest can establish along the channel, as seen on the Volturno River, narrowing is even more important. River widening in the early 2000s–2010s did not compensate for longer term narrowing, demonstrating a shift in river responsiveness that was partly due to upland and floodplain afforestation inducing higher channel resistance to bank erosion and bedload deficit. Such morphological evolution was also observed in Southeastern France, but occurred a bit earlier, with stronger similarities with northern Italy and the Apennines. These drivers of change must not be underestimated in geomorphic diagnosis, even if they are more difficult to assess.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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