Geosciences, Volume 10, Issue 12 (December 2020) – 33 articles

Maar volcanoes are monogenetic landforms whose craters cut below the pre-eruptive surface and are surrounded by a tephra ring. Both the maar crater and the surrounding tephra rim deposits are typically formed due to magma–water explosive interactions. Northern Chile is located in the Central Volcanic Zone of the Andes where, in literature, 14 maars have been recognized as parasite (6) and individual (8) volcanoes. Amongst these individual maars, 3 of them, namely the Tilocálar Sur, Cerro Tujle, and Cerro Overo volcanoes, are not related to calderas and were emplaced <1 Ma ago by magmatic explosive-effusive and phreatomagmatic eruptions. Based on the evolution and control of the volcanic eruptive styles of these three maars, which have been determined in previous research through fieldwork, stratigraphic, morphometric, textural (density and vesicularity), petrographic, and geochemical analyses, a set of key features that favor a prediction of the emplacement location of maar volcanoes in Central Andes, northern Chile are proposed. The set of features that permit and favor the growth mechanisms for maar formations corresponds to (i) a compressive tectonic setting (e.g., ridge structures), (ii) groundwater recharge (e.g., snowmelt and seasonal rainfall), (iii) the lithological setting (e.g., layers of low permeability), (iv) the presence of aquifer and/or endorheic basins (e.g., lakes or salars), and (v) a period of stress relaxation that permits magma ascent to the surface in volcanically active areas. Considering these characteristics, it is possible to identify places where phreatomagmatic eruption can occur. If the magma ascent flux is lower than the groundwater flux, this can lead to a phreatomagmatic eruption because of groundwater coming into contact with the magma. These eruptive features evidence internal—and external—factors that play an essential role in the transition from explosive-effusive magmatic to phreatomagmatic volcanic eruption styles during the same eruptive period that is one of the biggest challenges in volcanic hazard evaluations. Although, in this contribution, a set of features that permit and favor the growth mechanisms for a prediction of the emplacement location of maars in northern Chile is proposed, these considerations could also be applied to identify potential locations in other parts of the world where magma–water interaction eruption could occur. Therefore, this approach could be useful in the prediction of hydromagmatic volcanic eruptions and, thus, in mitigating the impact of volcanic hazard for the inhabitants of the surrounding areas. Full article

The Paleo Elbe Valley is the most prominent subsurface structure in the southern North Sea. During the Weichselian (marine isotope stage (MIS) 2), the valley traversed the exposed sea floor and drained the southern margin of the Scandinavian ice sheet. Today the valley is filled with up to 16 m thick sediments, but the responsible processes and drivers remain unknown. To unravel these processes and describe the valley’s evolution with Holocene transgression, we use shallow seismic data and vertical high-resolution grain-size core data. At the base of the western shore, supralittoral fine sands are overlain by a thin layer of clay dated to 9.8 cal. ka BP. The major sediment package consists of marine silt with internal seismic reflectors inclined in a northeastern direction, indicating a sediment transport from the southwest. The valley infill started when the western shore was flooded around 9.6 cal. ka BP and can be divided into two phases. During the first one (9.6–8.1 cal. ka BP) the sedimentation rate was highly driven by wind and waves. The second phase (8.1–5.0 cal. ka BP) was mainly tidal dominated but shows also storm event deposits in the north. Around 5.0 cal. ka BP the valley was almost filled. Full article

The key factors controlling the formation and dynamics of relicpermafrost and the conditions for the stability of associated gas hydrates have been investigated using numerical modeling in this work. A comparison was made between two scenarios that differed in the length of freezing periods and corresponding temperature shifts to assess the impact on the evolution of the permafrost–hydrate system and to predict its distribution and geometry. The simulation setup included the specific heat of gas hydrate formation and ice melting. Significantly, it was shown that the paleoscenario and heat flows affect the formation of permafrost and the conditions for gas hydrate stability. In the Laptev Sea, the minimum and maximum predicted preservation times for permafrost are 9 and 36.6 kyr, respectively, whereas the presence of conditions consistent with methane hydrate stability at the maximum permafrost thickness is possible for another 25.9 kyr. The main factors influencing the rate of permafrost degradation are the heat flow and porosity of frozen sediments. The rates of permafrost thawing are estimated to be between 1 and 3 cm/yr. It is revealed that the presence of gas hydrates slows the thawing of the permafrost and feeds back to prolong the conditions under which gas hydrates are stable. Full article

Cultural heritage represents our legacy with the past and our identity. However, to assure heritage can be passed on to future generations, it is required to put into the field knowledge as well as preventive and safeguard actions, especially for heritage located in seismic hazard-prone areas. With this in mind, the article deals with the analysis of ground response in the Avellino town (Campania, Southern Italy) and its correlation with the effects caused by the 23rd November 1980 Irpinia earthquake on the historical buildings. The aim is to get some clues about the earthquake damage cause-effect relationship. To estimate the ground motion response for Avellino, where strong-motion recordings are not available, we made use of the seismic hazard disaggregation. Then, we made extensive use of borehole data to build the lithological model so being able to assess the seismic ground response. Overall, results indicate that the complex subsoil layers influence the ground motion, particularly in the lowest period (0.1–0.5 s). The comparison with the observed damage of the selected historical buildings and the maximum acceleration expected indicates that the damage distribution cannot be explained by the surface geology effects alone. Full article

This work presents an analysis of the ESA Swarm satellite magnetic data preceding the Mw = 7.1 California Ridgecrest earthquake that occurred on 6 July 2019. In detail, we show the main results of a procedure that investigates the track-by-track residual of the magnetic field data acquired by the Swarm constellation from 1000 days before the event and inside the Dobrovolsky’s area. To exclude global geomagnetic perturbations, we select the data considering only quiet geomagnetic field time, defined by thresholds on Dst and a_p geomagnetic indices, and we repeat the same analysis in two comparison areas at the same geomagnetic latitude of the Ridgecrest earthquake epicentre not affected by significant seismicity and in the same period here investigated. As the main result, we find some increases of the anomalies in the Y (East) component of the magnetic field starting from about 500 days before the earthquake. Comparing such anomalies with those in the validation areas, it seems that the geomagnetic activity over California from 222 to 168 days before the mainshock could be produced by the preparation phase of the seismic event. This anticipation time is compatible with the Rikitake empirical law, recently confirmed from Swarm satellite data. Furthermore, the Swarm Bravo satellite, i.e., that one at highest orbit, passed above the epicentral area 15 min before the earthquake and detected an anomaly mainly in the Y component. These analyses applied to the Ridgecrest earthquake not only intend to better understand the physical processes behind the preparation phase of the medium-large earthquakes in the world, but also demonstrate the usefulness of a satellite constellation to monitor the ionospheric activity and, in the future, to possibly make reliable earthquake forecasting. Full article

The paper presents a review of the architecture and structures of river deposits in valleys. A new terminology for some features is included in this review. It presents principles of the fluvial systems with morphological river terraces and fluments (new term for terrace bodies), different stages of the morphological terraces, the texture—the arrangement—of fluments in the form of terrace flights, terrace stacks and terrace rows, and the (inner) structure of a single flument. The contact between the valley fill and the bedrock is named by the new term “pelma”. Special topics deal with flument overlaps and insight into the deepest valley fill down to the bedrock. A comparison with other terms of the fluvial inventory is annexed. Full article

The terminal velocity of hailstones is an essential quantity in hail research. It is an important value for the kinetic energy of hailstones and has to be carefully considered when laboratory hail impact testing is being planned. Many standardized hail impact testing procedures require specific impact velocities. Several empirical models for various hailstone diameter ranges have been developed to calculate the velocity based on the diameter, indicating somewhat inconsistent results. The velocity is influenced by factors such as their density, drag coefficient, shape or air density, and strong winds. This article takes a closer look into each of these factors and how they influence the velocity of hailstones and the damage potential of hailstorms. Implications are made for laboratory testing of hail impact testing procedures and how the geographic location of hailstorms might be a considerable factor when designing a test. Full article

The evaluation of natural periods and related mode shapes of earth dams represents a critical issue when performing structure-specific probabilistic seismic hazard analyses (PSHA). The identification of critical scenario events, using techniques such as disaggregation of the seismic hazard, and the calculation of a suitable target spectrum for ground motion selection and scaling procedures (e.g., the conditional mean spectrum), require at least the knowledge of the fundamental period of the system. This problem can be solved using analytical, numerical, and/or empirical techniques. We present several linear elastic modal analyses for an earth dam located in Southern Italy, using a numerical solution of the generalized eigenvalue problem obtained by the finite element method (FEM). Our numerical experiments are performed, testing various assumptions on boundary conditions, degree of saturation, and the distribution of geotechnical characteristics of the dam’s materials. We then compare our results against existing analytical solutions. We show that ignoring soil–structure interaction effects due to the flexibility of the dam foundation (i.e., under the assumption of fixed base) can lead to a substantial underestimation of the fundamental period of the dam. This effect should be carefully addressed when modal analysis results are used in PSHA-related applications. Full article

This paper describes the long-standing interdisciplinary geodynamic research for the wider Zagreb area, the most seismically active area of the continental part of the Republic of Croatia, extending over an area of around 800 km². As a result of the research, which is based on geodetic and geological field measurements, a unique interdisciplinary movement model of the surface layers of the Earth’s crust for the project area is created. The analysis of survey data has determined the continuous tectonic activity of the wider Zagreb area. In the past 18 years, a total of 10 GPS measurement campaigns have been conducted. For each campaign, the velocities of geodynamic network points were calculated, and the cumulative velocity rate was determined from all measurement campaigns for the entire period of observations using GAMIT/GLOBK software. Displacements at individual measuring points of the network, throughout research, vary widely and depend on its location within the local geologic structural framework and regional tectonic movements. These displacements in detail represent a measurable insight into the tectonic activity of the area of research. Therefore, in this paper, special attention is given to the analysis and explanation of these variations in the displacements of the individual geodynamic points, even indicating the questionable quality of location selection for some points. In this way, we seek to explain the causes and mechanisms of such displacements. The results presented in this paper represent the preseismic area condition and further can be used in coseismic 2020 earthquake displacement analysis. Full article

Coastal deposits/barriers react to sea-level rise through rollover or overstepping. Preserved coastal deposits/barriers allow us to examine coastal responses to sea-level rise, an important aspect within the context of climate change. This study identifies the Ofanto incised valley and examines the possible factors that caused the considerable difference in shape between this valley and adjacent valleys: the Carapelle and Cervaro incised valley and Manfredonia incised valley. In addition, this study assesses the response of transgressive units to stepped sea-level rise with a focus on the evolution of palaeo-barriers/shorelines on the continental shelf and within the infill of Ofanto incised valley. We identified the traces of two slowstands in sea-level rise: the first, short-lived at a centennial scale, interrupted Meltwater Pulse 1A; the second is referable to part of Bølling-Allerød and Younger Dryas. During these two slowstands, two barrier-shoreface/estuarine-backbarrier systems formed. Meltwater Pulse 1A and Meltwater Pulse 1B led to overstepping and partial preservation of these systems in the form of aligned topographic highs. The second slowstand gave rise to continuous landward backstepping of the coastal barrier system; during the following Meltwater Pulse 1B (MWP-1B), landward rollover of the coeval barrier/backbarrier system occurred. Full article

Backscatter data from multibeam echosounders are commonly used to classify seafloor sediment composition. Previously, it was found that the survey azimuth affects backscatter when small organized seafloor structures, such as sand ripples, are present. These sand ripples are too small to be detected in the multibeam bathymetry. Here, we show that such azimuth effects are time dependent and are useful to examine the orientation of sand ripples in relation to the flow direction of the tide. To this end, multibeam echosounder data at four different frequencies were gathered from the area of the Brown Bank in the North Sea. The acoustic results were compared to video and tide-flow data for validation. The sand ripples affected the backscatter at all frequencies, but for the lowest frequencies the effect was spread over more beam angles. Using the acoustic data made it possible to deduce the orientations of the sand ripples over areas of multiple square kilometers. We found that the top centimeter(s) of the seafloor undergoes a complete transformation every six hours, as the orientation of the sand ripples changes with the changing tide. Our methodology allows for morphology change detection at larger scales and higher resolutions than previously achieved. Full article

Microplastics are a fast-emerging group of contaminants. Their worldwide occurrence in water, sediment, and aquatic fauna raises questions and concerns as to their probable effects on aquatic life and ecology. This study investigates for the first time presence, abundance, and types of microplastics in water and sediment from a lagoon bordering the large urban agglomeration of Lagos in Nigeria, and renders additional information about the sediment composition. Water and sediment samples were collected from four locations in the Lagos Lagoon and a tributary. The abundance and distribution of microplastics in four range classes were determined for the sampled locations. Plastic particles were counted using digital microscopy, and identified with Fourier Transform-Infrared Spectroscopy (FTIR) and pyrolysis Gas Chromatography–Mass Spectrometry (GC-MS). The abundance of microplastics ranged from 310–2319 particles/kg in sediment, and 139–303 particles/L in water. The large discrepancy in the sediments can be explained by sediment characteristics as more microplastics were detected in the fine-grained sediments of Makoko. Fibres were the predominant shape found in all samples followed by fragments and few films. Fibres were more abundant in water (92.6%) than in sediments (32.5%), while more fragments and foils occurred in sediments. The most commonly used polymers polypropylene and polyethylene were also the most detected ones in both matrices. Compared to other studies in Nigeria, our findings especially in the coarser sediments were lower while the fine-grained site revealed similar results. Full article

The M_S 6.9, 1980 Irpinia earthquake occurred in the southern Apennines, a fold and thrust belt that has been undergoing post-orogenic extension since ca. 400 kyr. The strongly anisotropic structure of fold and thrust belts like the Apennines, including late-orogenic low-angle normal faults and inherited Mesozoic extensional features besides gently dipping thrusts, result in a complex, overall layered architecture of the orogenic edifice. Effective decoupling between deep and shallow structural levels of this mountain belt is related to the strong rheological contrast produced by a fluid-saturated, shale-dominated mélange zone interposed between buried autochthonous carbonates—continuous with those exposed in the foreland to the east—and the allochthonous units. The presence of fluid reservoirs below the mélange zone is shown by a high V_P/V_S ratio—which is a proxy for densely fractured fluid-saturated crustal volumes—recorded by seismic tomography within the buried autochthonous carbonates and the top part of the underlying basement. These crustal volumes, in which background seismicity is remarkably concentrated, are fed by fluids migrating along the major active faults. High pore fluid pressures, decreasing the yield stress, are recorded by low stress-drop values associated with the earthquakes. On the other hand, the mountain belt is characterized by substantial gas flow to the surface, recorded as both distributed soil gas emissions and vigorous gas vents. The accumulation of CO₂-brine within a reservoir located at hypocentral depths beneath the Irpinia region is not only interpreted to control a multiyear cyclic behavior of microseismicity, but could also play a role in ground motions detected by space-based geodetic measurements in the postseismic period. The analysis carried out in this study of persistent scatterer interferometry synthetic aperture radar (PS-InSAR) data, covering a timespan ranging from 12 to 30 years after the 1980 mainshock, points out that ground deformation has affected the Irpinia earthquake epicentral area in the last decades. These ground motions could be a result of postseismic afterslip, which is well known to occur over years or even decades after a large mainshock such as the 23 November 1980, M_S 6.9 earthquake due to cycles of CO₂-brine accumulation at depth and its subsequent release by M_w ≥ 3.5 earthquakes, or most likely by a combination of both. Postseismic afterslip controls geomorphology, topography, and surface deformation in seismically active areas such as that of the present study, characterized by ~M 7 earthquakes. Yet, this process has been largely overlooked in the case of the 1980 Irpinia earthquake, and one of the main aims of this study is to fill such the substantial gap of knowledge for the epicentral area of some of the most destructive earthquakes that have ever occurred in Italy. Full article

Study of the deep structure of the White Sea region is relevant to active geodynamics, manifestations of kimberlite magmatism, and the prospects of oil and gas searches. The aim of this work was to model the velocity and density structure of the earth’s crust in the White Sea region. Modelling was carried out using the known data of instrumental observations and the software complex “Integro”. With the help of 2D models based on deep seismic sounding (DSS) profiles and a digital map of the anomalous gravity field, the density structures of local areas of the region’s crust were refined. A 3D density model was built. Within the framework of this model, the positions of the density layers were determined. The relief of the Mohorovichich (Moho or M) discontinuity reflects the anomalies of the gravity field. Depression of the Moho boundary in the bottleneck of the White Sea indicates the vertical structure of the earth’s crust associated with manifestations of kimberlite magmatism. Full article

In this paper an elastic settlement analysis method for rigid rectangular footings applicable to both clays and sands is proposed. The proposed method is based on the concept of equivalent shape, where any rectangular footing is suitably replaced by a footing of elliptical shape; the conditions of equal area and equal perimeter are satisfied simultaneously. The case of clay is differentiated from the case of sand using different contact pressure distribution, whilst, additionally, for the sands, the modulus of elasticity increases linearly with depth. The method can conveniently be calibrated against any set of settlement data obtained analytically, experimentally, or numerically; in this respect the authors used values which have been derived analytically from third parties. Among the most interesting findings is that sands produce “settlement x soil modulus/applied pressure” values approximately 10% greater than the respective ones corresponding to clays. Moreover, for large Poisson’s ratio (v) values, the settlement of rigid footings is closer to the settlement corresponding to the corner of the respective flexible footings. As v decreases, the derived settlement of the rigid footing approaches the settlement value corresponding to the characteristic point of the respective flexible footing. Finally, corrections for the net applied pressure, footing rigidity, and non-elastic response of soil under loading are also proposed. Full article

Considering the foreland fold belt of the Salakh Arch in the northern Oman Mountains, predictions made from two-dimensional (2D) restorations and geometrical analyses are tested here to assess the relationship between large-scale folds and small-scale fractures. The Salakh Arch is composed of six anticlines that are interpreted as faulted detachment folds. They have an overall stratigraphy of a 2-km-thick carbonate platform underlain by more than 1.5 km of interbedded sandstone and shale sequences. These sequences are most likely detached on a regionally extensive evaporite horizon. The folding of the Salakh Arch structures most likely occurred during the Neogene Period, and perhaps partly in the early Quaternary Period. This is evident from the thrusting of the Late Neogene Barzaman Formation which was deposited during the Late Neogene Period. Robust outcrop and subsurface fracture data are used to test these predictions. The results from the study indicate that most fractures are related to the orientation of the local structure, with some sets parallel and some sets perpendicular to local hinge lines. Prefolding regional fractures are also widely distributed, and these were mostly formed during the Late Cretaceous Period. Many pre-existing fractures are associated with faults that formed during the Late Cretaceous Period under a NW–SE compression. The local fractures generally have orientations that are consistent with being formed by the flexural slip/flexural flow of fold limbs and tangential longitudinal strains on fold hinges. These structures can be predicted from finite stratal dips, simple curvatures, and three-dimensional (3D) folding restoration maps. The Gaussian curvatures and 3D faulting restoration maps can be used as proxies for fault-related fractures. Local hinge-related fractures may reflect local tangential longitudinal strain during large-scale fold tightening. Fold structures that have formed at an oblique orientation to the regional shortening direction show additional fracture arrays perpendicular to the hinge, indicating weak axial extension. This is presumed to develop as the arcuate thrust belt of Salakh Arch was amplified. The analysis here illustrates the importance of taking a 3D approach, especially for noncylindrical folds. The protocols developed in this study and their results may have general applicability to investigations of fracture patterns in other folds. Full article

The Markul settlement is an architectural site of the local population of northwestern Colchis. It is located in the village of Markula, Ochamchira region, Republic of Abkhazia. Traditional and modern digital methods are combined here to study the settlement. Panorama images acquired by a drone are used to outline a final orthometric model of the landscape of the entire settlement. An ancient road was discovered after detailed analysis of the finished model. Field studies have confirmed the existence of the road. Photogrammetry is similarly used here to study the architectural remains of the Alakhash-abaa tower and the results suggest that it was erected in the Roman period. The excavation results also support this conclusion. Full article

The paper discusses the impact that the quality of the digital elevation model (DEM) has on the final result of landslide susceptibility modeling (LSM). The landslide map was developed on the basis of the analysis of archival geological maps and the Light Detection and Ranging (LiDAR) digital elevation model. In addition, complementary field studies were conducted. In total, 92 landslides were inventoried and their degree of activity was assessed. An inventory of the landslides was prepared using a 1-m-LiDAR DEM and field research. Two digital photogrammetric elevation models with an elevation pixel resolution of 20 m were used for landslide susceptibility modeling. The first digital elevation model was obtained from a LiDAR point cloud (DEM–airborne laser scanning (ALS)), while the second model was developed based on archival digital stereo-pair aerial images (DEM–Land Parcel Identification System (LPIS)). Both models were subjected to filtration using a Gaussian low-pass filter to reduce errors in their elevation relief. Then, using ArcGIS software, a differential model was generated to illustrate the differences in morphology between the models. The maximum differences in topographic elevations between the DEM–ALS and DEM–LPIS models were calculated. The Weights-of-Evidence model is a geostatistical method used for the landslide susceptibility modeling. Six passive factors were employed in the process of susceptibility generation: elevation, slope gradient, exposure, topographic roughness index (TRI), distance from tectonic lines, and distance from streams. As a result, two landslide susceptibility maps (LSM) were obtained. The accuracy of the landslide susceptibility models was assessed based on the Receiver Operating Characteristic (ROC) curve index. The area under curve (AUC) values obtained from the ROC curve indicate that the accuracy of classification for the LSM–DEM–ALS model was 78%, and for the LSM–LPIS–DEM model was 73%. Full article

An interdisciplinary study based on lithostratigraphic, biostratigraphic, petrographic and mineralogical analyses has been performed in order to establish the Cenozoic tectono-sedimentary evolution of the El Habt and Ouezzane Tectonic Units (External Intrarif Subzone, External Rif, Morocco). The reconstructed record allowed identification of the depositional architecture and related sedimentary processes of the considered units. The Cenozoic successions were biochronologically defined allowing, at the same time, identification of unconformities and associated stratigraphic gaps. The presence of five unconformities allowed for the definition of the main stratigraphic units arranged in a regressive trend: (1) lower Paleocene interval (Danian p.p.) assigned to a deep basin; (2) Eocene interval (lower Ypresian-lower Bartonian p.p.) from a deep basin to an external carbonate-siliceous platform; (3) lower Rupelian-upper Chattian p.p. interval deposited on unstable slope with turbidite channels passing upward to an external siliciclastic platform; (4) Burdigalian p.p. interval from a slope; (5) Langhian-Serravallian p.p. interval from slope to external platform realms. The petrography of the arenites and calcarenites allowed for the identification of the supplies derived from erosion of a recycled orogen (transitional and quartzose subtypes). The clay-mineralogy analysis indicates an unroofing (first erosion of Cretaceous terrains followed by upper Jurassic rocks) always accomplished by erosion of Cenozoic terrains. Several tectofacies checked in some stratigraphic intervals seem to indicate the beginning of deformation of the basement generating gentle folds and first activation of blind thrusts, mainly during the Paleogene. A preorogenic tectonic framework is considered as responseto the generalized tectonic inversion (from extension to compression) as frequently registered in the central-western peri-Mediterranean areas. The large volumes of reworked terrigeneous supply during the latest Oligocene-Miocene p.p. indicates the beginningsof the synorogenic sedimentation (foredeep stage of the basins) controlled by active tectonics. Full article

In an urban environment, it is often necessary to locate structures close to existing retaining walls due to congestion in space. When such structures are in seismically active zones, the dynamic loading attracted by the retaining wall can increase. In a novel approach taken in this paper, finite element-based numerical analyses are presented for the case of a flexible, cantilever sheet pile wall with and without a structure on the backfill side. This enables a direct comparison of the influence exerted by the structure on the dynamic behaviour of the retaining wall. In this paper, the initial static bending moments and horizontal stresses prior to application of any earthquake loading are compared to Coulomb’s theory. The dynamic behaviour of the retaining wall is compared in terms of wall-top accelerations and bending moments for different earthquake loadings. The dynamic structural rotation induced by the differential settlements of the foundations is presented. The accelerations generated in the soil body are considered in three zones, i.e., the free field, the active and the passive zones. The differences caused by the presence of the structure are highlighted. Finally, the distribution of horizontal soil pressures generated by the earthquake loading behind the wall, and in front of the wall is compared to the traditional Mononobe-Okabe type analytical solutions. Full article

Sixty-six new archaeological sites have been discovered thanks to the combined use of different remote sensing techniques and open access geospatial datasets (mainly aerial photography, satellite imagery, and airborne LiDAR). These sites enhance the footprint of the Roman military presence in the northern fringe of the River Duero basin (León, Palencia, Burgos and Cantabria provinces, Spain). This paper provides a detailed morphological description of 66 Roman military camps in northwestern Iberia that date to the late Republic or early Imperial eras. We discuss the different spatial datasets and GIS tools used for different geographic contexts of varied terrain and vegetation. Finally, it stresses out the relevance of these novel data to delve into the rationale behind the Roman army movements between the northern Duero valley and the southern foothills of the Cantabrian Mountains. We conclude that methodological approaches stimulated by open-access geospatial datasets and enriched by geoscientific techniques are fundamental to understand the expansion of the Roman state in northwestern Iberia during the 1st c. BC properly. This renewed context set up a challenging scenario to overcome traditional archaeological perspectives still influenced by the cultural-historical paradigm and the pre-eminence of classical written sources. Full article

By using thermal mathematical modeling for the time range of 200,000 years ago, the authors have been studying the role the glaciation, covered the De Long Islands and partly the Anjou Islands at the end of Middle Neopleistocene, played in the formation of permafrost and gas hydrates stability zone. For the modeling purpose, we used actual geological borehole cross-sections from the New Siberia Island. The modeling was conducted at geothermal flux densities of 50, 60, and 75 mW/m² for glacial and extraglacial conditions. Based on the modeling results, the glaciated area is characterized by permafrost thickness of 150–200 m lower than under extraglacial conditions. The lower boundary of the gas hydrate stability zone in the glacial area at 50–60 mW/m² is located 300 m higher than the same under extraglacial conditions. At 75 mW/m² in the area of 20–40 m isobaths, open taliks are formed, and the gas hydrate stability zone was destroyed in the middle of the Holocene. The specified conditions and events were being formed in the course of the historical development of the glacial area with a predominance of the marine conditions peculiar to it from the middle of the Middle Neopleistocene. Full article

Landslide susceptibility mapping is of critical importance to identify landslide-prone areas to reduce future landslides, causalities, and infrastructural damages. This paper presents landslide susceptibility maps at a regional scale for the Chittagong Hilly Areas (CHA), Bangladesh. The frequency ratio (FR) was integrated with the analytical hierarchy process (AHP) (FR_AHP) and logistic regression (LR) (FR_LR). A landslide inventory of 730 landslide locations and 13 landslide predisposing factors including elevation, slope, aspect, plan curvature, profile curvature, topographic wetness index (TWI), stream power index (SPI), land use/land cover, rainfall, distance from drainage network, distance from fault lines, lithology, and normalized difference vegetation index (NDVI) were used. Landslide locations were randomly split into training (80%) and validation (20%) sites to support the susceptibility analysis. A safe zone was determined based on a slope threshold for logistic regression using the exploratory data analysis. The same number of non-landslide locations were randomly selected from the safe zone to train the model (FR_LR). Success and prediction rate curves and statistical indices, including overall accuracy, were used to assess model performance. The success rate curves show that FR_LR showed the highest area under the curve (AUC) (79.46%), followed by the FR_AHP (77.15%). Statistical indices also showed that the FR_LR model gave the best performance as the overall accuracy was 0.86 for training and 0.82 for validation datasets. The prediction rate curve shows similar results. The correlation analysis shows that the landslide susceptibility maps produced by FR and FR_AHP are highly correlated (0.95). In contrast, the correlation between the maps produced by FR and FR_LR was relatively lower (0.85). It indicates that the three models are highly convergent with each other. This study’s integrated methods would be helpful for regional-scale landslide susceptibility mapping, and the landslide susceptibility maps produced would be useful for regional planning and disaster management of the CHA, Bangladesh. Full article

The November 23rd, 1980 Irpinia-Basilicata (Southern Italy) earthquake is one of the strongest earthquakes ever occurred in Italy. The earthquake was a natural laboratory for the scientific community, which was engaged highly and promptly in investigating the event, thus publishing a flood of papers in different research areas over time. Just these research outputs are the focus of the article, which examines, with a tailored methodological approach, the international and national (Italian) studies started and advanced since the occurrence of the earthquake. First, we built and analyzed statistically two bibliographic databanks regarding the earthquake studies: (a) the international version of IRpinia Bibliographic databASE (IR_BASE_ENG), selecting and standardizing the pertinent scientific documents extracted from Scopus, Web of Science, and other databases and (b) the national version of the database (IR_BASE_IT) using the Google Scholar search engine to search for the most relevant papers in Italian. Second, IR_BASE_ENG was analyzed in a bibliometric perspective through the data mining VOSviewer software (Waltman et al., 2010) that builds co-occurrence term maps useful in perspective of investigating the wide-ranging studies on the earthquake. Third, taking a cue from this network analysis, we recognized the main research topics and performed a minireview of the related international studies, integrating in it a quick reference to the literature in Italian. Finally, we associated the scientific outputs to each cluster/topic, also performing the frequency analysis of the published documents for each subject, thus gaining information on the temporal trends of studies and getting a more exhaustive evidence of the scientific landscape on the earthquake over the last 40 years. Full article

Investigating tsunamis and cyclones from depositional records enables an understanding of the long-term hazards to coastal communities. In Samoa, whilst a long-term record of tsunamis and cyclones spanning the last few millennia has been previously suggested based on preliminary sediment core/trench studies, a detailed assessment of the characteristics distinguishing these events has not been presented. This study reevaluates the depositional evidence available for Samoa and offers a more robust interpretation of the temporal and spatial records of tsunami events preserved in the Samoan sedimentary record. Tsunami inundation and runup records of the 2009 South Pacific tsunami along with differences in depositional settings, and sedimentary and geochemical characteristics of the associated deposits provide modern analogies for interpreting comparable older event-type deposits deeper in the Samoan geological record. These are aided by the 1990/1991 Cyclones Ofa and Val deposits previously suggested at some sites, which provides a modern analogy for interpreting cyclone-related deposits. Available radiocarbon and radiometric dates for the core/trench sites provide time-indicators to identify contemporaneous events, which we use to interpret the long-term record of tsunamis in this island region. Full article

Several urban areas in the Mediterranean have already been subjected to seismic microzonation studies aimed at determining the acceleration expected on the ground surface, therefore mitigating the associated seismic risks. These studies have been generally related to free-field conditions. The present paper shows innovative seismic microzonation maps based on a large-scale estimate of soil-structure interaction (SSI) effects on design accelerations for some areas characterized by a high seismic risk in Catania, Italy. The proposed procedure combined: (1) geotechnical characteristics; (2) building features; and (3) 1-D seismic response analyses in free-field conditions. The seismic hazard and site effects were evaluated using artificial inputs and inputs recorded recently in Catania. Structural fundamental periods and related spectral accelerations, considering both the fixed-base building configuration and flexible-base configuration, were mapped in the Google My Maps environment. These results showed that SSI often had a beneficial effect, but sometimes it had detrimental effects, especially for some masonry buildings. These maps provided important information for planning the seismic retrofitting of investigated buildings, which were based on more detailed analyses of SSI and the developed maps requiring them. Full article

Land surface/ecosystem models (LSEMs) play a key role in understanding the Earth’s climate. They represent ecosystem dynamics by simulating fluxes occurring between the biosphere and atmosphere. However, for a correct flux simulation, it is critical to calibrate the model using robust and state-of-the-art calibration techniques. In this work, we optimize parameters of the Integrated Model of Land Surface Processes (INLAND) using the hierarchical multi-objective calibration method (AMALGAM) to improve the representation of surface processes in a natural ecosystem over the Pampa biome in South America. The calibration was performed using experimental data of energy and CO${}_2$ flux collected in a native field located in southern Brazil. We compared simulations using the default and calibrated parameter set. The results show that the calibration of the model significantly improved all fluxes analyzed. The mean errors and bias values were significantly reduced, and the seasonality of fluxes was better represented. This work is one of the first to apply a multi-objective calibration in an LSEM to represent surface fluxes in the Pampa biome, presenting a consistent set of parameters for future applications used in studies of biome land use and land cover. Full article

Over the years, floods have caused economic damage that has impacted development in many regions. As a result, a comprehensive overview of flood-prone areas at the provincial scale is important in order to identify zones that require detailed assessment with hydrodynamic models. This study presents two approaches that were used to prioritize flood-prone areas at the provincial scale in New Brunswick, Canada. The first approach is based on a spatial multi-criteria evaluation (SMCE) technique, while the second approach pertains to flood exposure analysis. The results show the variation in the identified flood-prone areas and, depending on the methodology and scenario used, prioritization changes. Therefore, a standard methodology might not be feasible and should be developed based on the objective of the study. The results obtained can be useful for flood risk practitioners when making decisions about where to commence detailed flood hazard and risk assessment. Full article