Geosciences

25 pages, 8398 KiB

Open AccessArticle

Outboard Onset of Ross Orogen Magmatism and Subsequent Igneous and Metamorphic Cooling Linked to Slab Rollback during Late-Stage Gondwana Assembly

by Timothy Paulsen, John Encarnación, Anne Grunow, Jeffrey Benowitz, Paul Layer, Chad Deering and Jakub Sliwinski

Geosciences 2023, 13(4), 126; https://doi.org/10.3390/geosciences13040126 - 21 Apr 2023

Viewed by 1507

Abstract

Changes in magmatism and sedimentation along the late Neoproterozoic-early Paleozoic Ross orogenic belt in Antarctica have been linked to the cessation of convergence along the Mozambique belt during the assembly of East-West Gondwana. However, these interpretations are non-unique and are based, in part, [...] Read more.

Changes in magmatism and sedimentation along the late Neoproterozoic-early Paleozoic Ross orogenic belt in Antarctica have been linked to the cessation of convergence along the Mozambique belt during the assembly of East-West Gondwana. However, these interpretations are non-unique and are based, in part, on limited thermochronological data sets spread out along large sectors of the East Antarctic margin. We report new ⁴⁰Ar/³⁹Ar hornblende, muscovite, and biotite age data for plutonic (n = 13) and metasedimentary (n = 3) samples from the Shackleton–Liv Glacier sector of the Queen Maud Mountains in Antarctica. Cumulative ⁴⁰Ar/³⁹Ar age data show polymodal age peaks (510 Ma, 491 Ma, 475 Ma) that lag peaks in U-Pb igneous crystallization ages, suggesting igneous and metamorphic cooling following magmatism within the region. The ⁴⁰Ar/³⁹Ar ages are similar to ages in other sectors of the Ross orogen, but younger than detrital mineral ⁴⁰Ar/³⁹Ar cooling ages indicative of older magmatism and cooling of unexposed inboard areas along the margin. Detrital zircon trace element abundances suggest that the widespread onset of magmatism in outboard localities of the orogen correlates with a ~560–530 Ma decrease in crustal thickness. The timing of crustal thinning recorded by zircon in magmas overlaps with other evidence for the timing of crustal extension, suggesting that the regional onset of magmatism with subsequent igneous and metamorphic cooling probably reflects slab rollback that coincided with possible global plate motion changes induced during the final assembly of Gondwana. Full article

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19 pages, 21492 KiB

Open AccessArticle

Failure Mechanism of a Rainfall-Triggered Landslide in Clay Slopes

by Piernicola Lollino, Angelo Ugenti, Daniela de Lucia, Mario Parise, Carmen Vennari, Paolo Allasia and Nunzio Luciano Fazio

Geosciences 2023, 13(4), 125; https://doi.org/10.3390/geosciences13040125 - 21 Apr 2023

Viewed by 1666

Abstract

In December 2013, a portion of a large and deep ancient landslide on the southern slope of the Montescaglioso town (Basilicata, Southern Italy) was abruptly reactivated, as a consequence of exceptional rainfall events, causing relevant damages to structures and infrastructures. The sliding surface [...] Read more.

In December 2013, a portion of a large and deep ancient landslide on the southern slope of the Montescaglioso town (Basilicata, Southern Italy) was abruptly reactivated, as a consequence of exceptional rainfall events, causing relevant damages to structures and infrastructures. The sliding surface is supposed to be located within a thick deposit of Pleistocene stiff clays overlain by dislocated blocks of calcarenites and cemented conglomerates. This paper discusses the research carried out to investigate the failure mechanism that occurred during the landslide event and the factors that controlled the reactivation. To this purpose, geological and geomorphological analyses were first proposed, followed by a back-analysis of the landslide process, performed via limit equilibrium calculations implementing time-dependent pore water pressure distributions derived from transient seepage finite element analyses. Furthermore, the overall landslide mechanism was investigated through a three-dimensional finite element analysis, built using the monitoring campaign carried out in the post-failure stage and calibrated according to the in situ failure mechanism evidence. Both the limit equilibrium and finite element analyses provide results in good agreement with the geomorphological evidence, further allowing us to recognize the effects of rainfall infiltration in the increase of pore water pressure along the sliding surface and the variation of the stress–strain state leading to failure occurrence. Full article

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14 pages, 2084 KiB

Open AccessPerspective

The Contributions of Marine Sediment Cores to Volcanic Hazard Assessments: Present Examples and Future Perspectives

by Chris Satow, Sebastian Watt, Mike Cassidy, David Pyle and Yuqiao Natalie Deng

Geosciences 2023, 13(4), 124; https://doi.org/10.3390/geosciences13040124 - 21 Apr 2023

Viewed by 2341

Abstract

The rigorous assessment of volcanic hazards relies on setting contemporary monitoring observations within an accurate, longer-term geological context. Revealing that geological context requires the detailed fieldwork, mapping and laboratory analysis of the erupted materials. However, many of the world’s most dangerous volcanic systems [...] Read more.

The rigorous assessment of volcanic hazards relies on setting contemporary monitoring observations within an accurate, longer-term geological context. Revealing that geological context requires the detailed fieldwork, mapping and laboratory analysis of the erupted materials. However, many of the world’s most dangerous volcanic systems are located on or near coasts (e.g., the Phlegraean Fields and Vesuvius in Italy), islands (e.g., the volcanic archipelagos of the Pacific, south-east Asia, and Eastern Caribbean), or underwater (e.g., the recently erupting Hunga Tonga–Hunga Ha’apai volcano), meaning that much of their erupted material is deposited on the sea bed. The only way to sample this material directly is with seafloor sediment cores. This perspectives paper outlines how marine sediment cores are a vital yet underused resource for assessing volcanic hazards by: (1) outlining the spatio-temporal scope of the marine volcanic record and its main deposit types, (2) providing existing examples where marine sediments have contributed to volcanic hazard assessments; (3) highlighting the Sunda Arc, Indonesia as an example location where marine sediment cores are yet to contribute to hazard assessments, and (4) proposing that marine sediment cores can contribute to our understanding of very large eruptions that have a global impact. Overall, this perspectives paper aims to promote the utility of marine sediment cores in future volcanic hazard assessments, while also providing some basic information to assist researchers who are considering integrating marine sediment cores into their volcanological research. Full article

(This article belongs to the Special Issue Marine Geohazards)

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16 pages, 2772 KiB

Open AccessArticle

Late Holocene Environmental History and Norse Settlement in Outer Fjords from South Greenland: A Case Study at Lake Qallimiut

by Emilie Gauthier, Andrés Currás, Charly Massa, Typhaine Guillemot, Hervé Richard and Vincent Bichet

Geosciences 2023, 13(4), 123; https://doi.org/10.3390/geosciences13040123 - 20 Apr 2023

Viewed by 1432

Abstract

To complement discussions about vegetation history and climate variations in south Greenland, especially during the Norse settlement, we developed a sedimentological multiproxy approach to study a 4300-year-old lacustrine core comprising pollen analysis, NPPs analysis, physical measurements (magnetic susceptibility, density, and grain size), and [...] Read more.

To complement discussions about vegetation history and climate variations in south Greenland, especially during the Norse settlement, we developed a sedimentological multiproxy approach to study a 4300-year-old lacustrine core comprising pollen analysis, NPPs analysis, physical measurements (magnetic susceptibility, density, and grain size), and geochemical analyses (X-ray fluorescence, X-ray diffraction, and elemental analyses). Sediment archives were retrieved from a river-fed lake, Lake Qallimiut, located in the outer fjords of the Vatnahverfi area. The pollen analysis indicated a transition from juniper and willow cover to a dwarf birch forest. Non-pollen palynomorphs (NPPs) suggested grazing pressure and the presence of wild herbivores between 2300 and 1800 cal. BC. From ca. 1000 cal. AD, the presence of Norse farmers was evidenced in this area by archaeological surveys, and pollen analyses confirm the presence of human activities from the 11th century to the end of the 13th century. However, human impact progressively vanished between the 12th and 13th centuries, much earlier than at the other Vatnahverfi sites. Full article

(This article belongs to the Special Issue Arctic Geoarchaeology and Environmental Archaeology)

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30 pages, 6535 KiB

Open AccessArticle

Outdoor River Activities: Relations with Geological Background and Extreme Events in the Perspective of Geoeducation

by Irene Maria Bollati, Davide Rossi and Cristina Viani

Geosciences 2023, 13(4), 122; https://doi.org/10.3390/geosciences13040122 - 20 Apr 2023

Cited by 3 | Viewed by 1587

Abstract

As for sport climbing, also for outdoor activities such as rafting and canyoning, a strong connection with geofeatures on a long and short time scale exists. For investigating this, three river segments were selected in the Sesia hydrographic basin (Sesia Val Grande UNESCO [...] Read more.

As for sport climbing, also for outdoor activities such as rafting and canyoning, a strong connection with geofeatures on a long and short time scale exists. For investigating this, three river segments were selected in the Sesia hydrographic basin (Sesia Val Grande UNESCO Global Geopark, Northwest Italy). Here, commercial rafting and canyoning activities are popular, and important geological features are present (Sesia Supervolcano, Insubric Line). The segments were investigated using partly IDRAIM (system for stream hydromorphological assessment, analysis, and monitoring). Bedrock features, confinement, sinuosity, bankfull bottom, morphological units, and steepness were characterized. The segments were hence divided in several reaches. Correlations on the long time scale were found mainly between the geology and bankfull bottom configuration, while sinuosity allowed us to highlight the possible structural control on the genesis of gorges. Moreover, the analysis of changes in a short time scale along the river segments after the extreme meteorological event occurred on 2–3 October 2020, highlighted a rapids difficulty variation, channels diversion, and woody–rocky debris accumulation in the bankfull, deeply influencing river activities. Through the proposed approach, new frontiers in the outreach of geosciences could be opened, especially in virtue of the several Sustainable Development Goals that could be achieved through river outdoor activities, among the others new employment opportunities for local operators. Full article

(This article belongs to the Section Geoheritage, Geoparks and Geotourism)

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20 pages, 10518 KiB

Open AccessArticle

Cenozoic Fault Growth Mechanisms in the Outer Apulian Platform

by Fabrizio Agosta, Angela Vita Petrullo, Vincenzo La Bruna and Giacomo Prosser

Geosciences 2023, 13(4), 121; https://doi.org/10.3390/geosciences13040121 - 19 Apr 2023

Cited by 1 | Viewed by 1159

Abstract

This work focuses on a ca. 55 km-long extensional fault zone buried underneath the foredeep deposits of the southern Apennines, Italy, with the goal of deciphering the Cenozoic fault growth mechanisms in the Outer Apulian Platform. By considering public 2D seismic reflection profiles, [...] Read more.

This work focuses on a ca. 55 km-long extensional fault zone buried underneath the foredeep deposits of the southern Apennines, Italy, with the goal of deciphering the Cenozoic fault growth mechanisms in the Outer Apulian Platform. By considering public 2D seismic reflection profiles, well logs, and isochron maps data, the study normal fault zone is interpreted as made up of four individual fault segments crosscutting Top Cretaceous, Top Eocene, Top Miocene, and Top Pliocene chrono-stratigraphic surfaces. The computed cumulative throw profiles form either bell-shaped or flat-shaped geometries along portions of the single fault segments. The computed incremental throw profiles also show an initial fault segmentation not corresponding with the present-day structural configuration. Data are consistent with the initial, post-Cretaceous fault segments coalescing together during Miocene–Pliocene deformation and with fault linkage processes localizing at the stepover/relay zones. Pleistocene faulting determined the evolution of a coherent fault system. The computed n-values obtained for the single time intervals by considering the maximum fault throw–fault length relations indicate that the fault segments formed scale-dependent geometries. Variations of these computed values are interpreted as due to the higher degree of maturity reached by the entire fault system during Miocene to Pleistocene deformation. Full article

(This article belongs to the Section Structural Geology and Tectonics)

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28 pages, 14850 KiB

Open AccessArticle

The Response of Sandstone Sea Cliffs to Holocene Sea-Level Rise by Means of Remote Sensing and Direct Surveys: The Case Study of Punta Licosa Promontory (Southern Italy)

by Maria Francesca Tursi, Antonio Minervino Amodio, Claudia Caporizzo, Silvio Del Pizzo, Francesco Giuseppe Figliomeni, Gaia Mattei, Claudio Parente, Carmen M. Rosskopf and Pietro P. C. Aucelli

Geosciences 2023, 13(4), 120; https://doi.org/10.3390/geosciences13040120 - 17 Apr 2023

Cited by 3 | Viewed by 1500

Abstract

Punta Licosa promontory is located in the northern part of the Cilento coast, in the southern Tyrrhenian basin. This promontory is bordered by sea cliffs connected to a wide shore platform sloping slightly towards the sea. This area has been considered stable at [...] Read more.

Punta Licosa promontory is located in the northern part of the Cilento coast, in the southern Tyrrhenian basin. This promontory is bordered by sea cliffs connected to a wide shore platform sloping slightly towards the sea. This area has been considered stable at least since Late Pleistocene, as testified by a series of evidence well known in the literature. The aim of this research is to reconstruct the main coastal changes that have occurred in this area since the middle Holocene by means of the literature data, aerial photo interpretation, satellite images, GPS measurements, direct underwater surveys, GIS elaborations of high-resolution DTMs, bathymetric data and high-resolution orthophotos taken by UAV. Particular attention was paid to the wide platform positioned between −7.2 ± 1.2 m MSL and the present MSL, this being the coastal landform interpreted as the main consequence of sea cliff retreat. The elevation of this landform was compared with the GIA models calculated for the southern Tyrrhenian area, allowing establishing that it was shaped during the last 7.6 ± 1.1 ky BP. Moreover, the interpretation of archaeological and geomorphological markers led to the reconstruction of the shoreline evolution of this coastal sector since 7.6 ky BP. This research evaluates the cliff retreat under the effect of Holocene RSL variation on Cilento promontories, located in the western Mediterranean and characterised by the presence of monophasic platforms, and the applied method can be considered more effective and less complex and expensive if compared to other effective approaches such as those based on the usage of cosmogenic nuclides. Full article

(This article belongs to the Special Issue Relative Sea-Level Rise)

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13 pages, 1271 KiB

Open AccessArticle

Analytical and Numerical Solutions for Three-Dimensional Granular Collapses

by Emmanuel Wyser, Yury Alkhimenkov, Michel Jaboyedoff and Yury Y. Podladchikov

Geosciences 2023, 13(4), 119; https://doi.org/10.3390/geosciences13040119 - 16 Apr 2023

Viewed by 1104

Abstract

This research paper presents a comprehensive approach to investigating dry granular collapses in three dimensions, by combining analytical, numerical, and experimental methods. The experimental investigation utilised a novel apparatus to study granular collapses in the laboratory. It is demonstrated that a quasistatic understanding [...] Read more.

This research paper presents a comprehensive approach to investigating dry granular collapses in three dimensions, by combining analytical, numerical, and experimental methods. The experimental investigation utilised a novel apparatus to study granular collapses in the laboratory. It is demonstrated that a quasistatic understanding of granular collapses can accurately predict the final normalised run-out distances for dynamic granular collapses. Our approach involved establishing a correlation between the angle of repose and the initial aspect ratio of the granular column. It is also shown that the material point method (MPM) is suitable for modelling granular collapses in three dimensions. Our in-house solver was further validated using experimental evidence under an explicit formulation, resulting in good agreement between the numerical and experimental results. The findings demonstrate the effectiveness of our in-house solver for three-dimensional granular collapse modelling. Full article

(This article belongs to the Section Geomechanics)

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25 pages, 13366 KiB

Open AccessArticle

Examining the Hydro-Climatic Drivers of Lagoon Breaching and Healing in a Deltaic Barrier

by Juan Felipe Gómez, Eva Kwoll, Ian J. Walker and Andrés F. Orejarena

Geosciences 2023, 13(4), 118; https://doi.org/10.3390/geosciences13040118 - 15 Apr 2023

Viewed by 2043

Abstract

As sea-level rise (SLR) and human-made interventions affect coastal currents and sediment transport, coastal barriers have become more vulnerable to the effect of storms, hurricanes, and climate variability. The response of each barrier is unique and depends on wave regime, coastline orientation, weather [...] Read more.

As sea-level rise (SLR) and human-made interventions affect coastal currents and sediment transport, coastal barriers have become more vulnerable to the effect of storms, hurricanes, and climate variability. The response of each barrier is unique and depends on wave regime, coastline orientation, weather conditions, bathymetry, and type of human-made interventions, among other factors. In the Magdalena River deltaic barrier, located on the Colombian Caribbean coast, coastal erosion has caused the loss of hundreds of square kilometers of critical ecosystems, such as wetlands and lagoons, since the 1960s. This work aims to analyze the short-term drivers behind the observed loss of lagoons, particularly the drivers of lagoon breaching events and subsequent healing along the deltaic barrier. Lagoon breaching events and healings were detected using satellite imagery, and the timing of these events was related to prior local atmospheric, oceanographic, and fluvial conditions. The findings reveal that the dynamics of the lagoons are driven by extreme river discharges and energetic wave conditions associated with storms or hurricanes. Healing is driven by the sediment supplied by littoral currents and average waves punctuated by energetic events. The cumulative effect of breaching and healing has resulted in a deltaic barrier that has rolled over the lagoons, reducing their size over time. These findings provide a better understanding of the forces of coastal retreat and will help inform future management decisions of the coastal zone. Full article

(This article belongs to the Special Issue Shoreline Dynamics and Beach Erosion, 2nd Edition)

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19 pages, 11700 KiB

Open AccessArticle

The First Rock Glacier Inventory for the Greater Caucasus

by Levan G. Tielidze, Alessandro Cicoira, Gennady A. Nosenko and Shaun R. Eaves

Geosciences 2023, 13(4), 117; https://doi.org/10.3390/geosciences13040117 - 13 Apr 2023

Cited by 5 | Viewed by 2572

Abstract

Rock glaciers are an integral part of the periglacial environment. At the regional scale in the Greater Caucasus, there have been no comprehensive systematic efforts to assess the distribution of rock glaciers, although some individual parts of ranges have been mapped before. In [...] Read more.

Rock glaciers are an integral part of the periglacial environment. At the regional scale in the Greater Caucasus, there have been no comprehensive systematic efforts to assess the distribution of rock glaciers, although some individual parts of ranges have been mapped before. In this study we produce the first inventory of rock glaciers from the entire Greater Caucasus region—Russia, Georgia, and Azerbaijan. A remote sensing survey was conducted using Geo-Information System (GIS) and Google Earth Pro software based on high-resolution satellite imagery—SPOT, Worldview, QuickBird, and IKONOS, based on data obtained during the period 2004–2021. Sentinel-2 imagery from the year 2020 was also used as a supplementary source. The ASTER GDEM (2011) was used to determine location, elevation, and slope for all rock glaciers. Using a manual approach to digitize rock glaciers, we discovered that the mountain range contains 1461 rock glaciers with a total area of 297.8 ± 23.0 km². Visual inspection of the morphology suggests that 1018 rock glaciers with a total area of 199.6 ± 15.9 km² (67% of the total rock glacier area) are active, while the remaining rock glaciers appear to be relict. The average maximum altitude of all rock glaciers is found at 3152 ± 96 m above sea level (a.s.l.) while the mean and minimum altitude are 3009 ± 91 m and 2882 ± 87 m a.s.l., respectively. We find that the average minimum altitude of active rock glaciers is higher (2955 ± 98 m a.s.l.) than in relict rock glaciers (2716 ± 83 m a.s.l.). No clear difference is discernible between the surface slope of active (41.4 ± 3°) and relict (38.8 ± 4°) rock glaciers in the entire mountain region. This inventory provides a database for understanding the extent of permafrost in the Greater Caucasus and is an important basis for further research of geomorphology and palaeoglaciology in this region. The inventory will be submitted to the Global Land Ice Measurements from Space (GLIMS) database and can be used for future studies. Full article

(This article belongs to the Special Issue Mountain Glaciers, Permafrost, and Snow)

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30 pages, 13100 KiB

Open AccessArticle

2D FEM Numerical Prediction of Local Seismic Effects at San Salvador Municipality (El Salvador) Induced by 2001 Earthquakes

by Chiara Faraone, Serena Caravaggio, José Alexander Chávez, Luis Alfonso Castillo Ramos, Mario Luigi Rainone and Giovanna Vessia

Geosciences 2023, 13(4), 116; https://doi.org/10.3390/geosciences13040116 - 13 Apr 2023

Viewed by 1539

Abstract

San Salvador Metropolitan Area (MASS) is an urbanized territory in the country of El Salvador, located between the San Salvador volcano and the Ilopango caldera, in a sub-flat area called “Valle de las Hamacas” (Valley of the Hammocks). The high seismicity [...] Read more.

San Salvador Metropolitan Area (MASS) is an urbanized territory in the country of El Salvador, located between the San Salvador volcano and the Ilopango caldera, in a sub-flat area called “Valle de las Hamacas” (Valley of the Hammocks). The high seismicity of this area is due to the subduction zone of the Cocos plate that causes strong seismic events such as the earthquakes that occurred on 13 January (7.6 M_w) and 13 February 2001 (6.6 M_w). As part of the international cooperation project between Italy (AICS) and El Salvador University, the CASTES project focussed on natural hazards in the territory of El Salvador was launched. Therefore, 2D simulations are carried out along two sections to evaluate the Local Seismic Response (LSR) in the Southeast part of MASS territory. Results show spatially variable amplifications (from 3 to 6.5) in the period ranging 0.1–0.7 s and evidence of lateral FA variations that can be calculated only through 2D numerical analyses. Two amplified periods are recognised, 0.1–0.5 s and 0.4–0.8 s, due to the presence of two types of subsoil volcanic deposits: the shallow and soft Tierra Blanca deposits and the deeper and stiffer Volcanic ash and Tuff. Full article

(This article belongs to the Special Issue Natural Hazards and Geological Risks in Subduction Zones)

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34 pages, 13584 KiB

Open AccessArticle

Twisting Theory: A New Artificial Adaptive System for Landslide Prediction

by Paolo Massimo Buscema, Weldon A. Lodwick, Masoud Asadi-Zeydabadi, Francis Newman, Marco Breda, Riccardo Petritoli, Giulia Massini, David Buscema, Donatella Dominici and Fabio Radicioni

Geosciences 2023, 13(4), 115; https://doi.org/10.3390/geosciences13040115 - 12 Apr 2023

Viewed by 1675

Abstract

Landslides pose a significant risk to human life. The Twisting Theory (TWT) and Crown Clustering Algorithm (CCA) are innovative adaptive algorithms that can determine the shape of a landslide and predict its future evolution based on the movement of position sensors located in [...] Read more.

Landslides pose a significant risk to human life. The Twisting Theory (TWT) and Crown Clustering Algorithm (CCA) are innovative adaptive algorithms that can determine the shape of a landslide and predict its future evolution based on the movement of position sensors located in the affected area. In the first part of this study, the TWT and CCA will be thoroughly explained from a mathematical and theoretical perspective. In the second part, these algorithms will be applied to real-life cases, the Assisi landslide (1995–2008) and the Corvara landslide (2000–2008). A correlation of 0.9997 was attained between the model estimates and the expert’s posterior measurements at both examined sites. The results of these applications reveal that the TWT can accurately identify the overall shape of the landslides and predict their progression, while the CCA identifies complex cause-and-effect relationships among the sensors and represents them in a clear, weighted graph. To apply this model to a wider area and secure regions at risk of landslides, it is important to emphasize its operational feasibility as it only requires the installation of GNSS sensors in a predetermined grid in the target area. Full article

(This article belongs to the Special Issue Geophysical Risks: The Future of Observatories, The Observatories of the Future)

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17 pages, 3028 KiB

Open AccessArticle

Rock Magnetism and Magnetic Fabric Study of the Icelandite and Rhyodacite Long Volcanic Sequence at Mauna Kuwale, Wai’anae Volcano, Oahu, Hawaii, USA

by Emilio Herrero-Bervera and Mario Moreira

Geosciences 2023, 13(4), 114; https://doi.org/10.3390/geosciences13040114 - 11 Apr 2023

Viewed by 1197

Abstract

In order to understand further the emplacement (i.e., volcanic growth) of 22 Icelandite and 3 Rhyodacite cooling units in one of the long volcanic sequences known as Mauna Kuwale of the Wai’anae volcano (ca. 3.3 Ma), Oahu Hawaii we have conducted appropriate rock [...] Read more.

In order to understand further the emplacement (i.e., volcanic growth) of 22 Icelandite and 3 Rhyodacite cooling units in one of the long volcanic sequences known as Mauna Kuwale of the Wai’anae volcano (ca. 3.3 Ma), Oahu Hawaii we have conducted appropriate rock magnetic experiments described below as well as anisotropy of magnetic susceptibility (AMS) studies of such 25 units. We have undertaken rock magnetic investigations such as continuous and partial thermo-magnetic cycles of low field magnetic susceptibility versus temperature dependence, (k-T) curves experiments. We classified the k-T heating-cooling dependence of susceptibility in three groups A, B and C. Type A: yielded two components of titano-magnetite with a predominat Ti rich phase and occasionally a relevant magnetite component phase. Type B: samples are characterized by Ti poor magnetites. Magnetite dominates as the main magnetic carrier. Type C: k-T curves show one single phase of titanomagnetite, and Ti poor magnetite. The coercivity or remanence, determined by back field magnetization is always <60 mT, which suggest the predominance of magnetic components of low coercivity, like magnetite. Usually, two coercivity components are identified in the specimens. In addition we also conducted magnetic granulometry analyses on 27 specimens to determine the domain state of the flows. The ratio of hysteresis parameters (Mr/Mrs versus Hcr/Hc) show that overall samples fall in the Pseudo-Single Domain (PSD) region with high values of Mr/Mrs and very low values of Hcr/Hc. Only two samples from cooling units 17 and specially 22 show a Single Domain (SD) magnetic behavior and a sample from one unit approaches the SD-MD mixture region. We measured the magnetic susceptibility of all cooling units and we found out that in all analyzed units the magnetic susceptibility is low 13.7 ± 8.8 (10⁻³ SI). Magnetic anisotropy/magnetic fabric is used as a tool in rock fabric analyses to investigate the preferred orientation of magnetic minerals in rocks. Magnetic anisotropy is low on all (measured) flows from the Icelandite cooling units from 1 to 17 (mean P’ = 1.010), but becomes noticeably distinct and high in rhyodacite cooling units 23, 24 and 25 (mean P’ = 1.074). Four units show a magnetic fabric with k₃ axes vertical to sub-vertical which may be denoted as normal for the horizontal to sub horizontal units. Two Icelandite cooling units display oblate shapes and two other cooling units triaxial shapes. K₁ axes are horizontal but point in different directions, i.e., NE and NW. Remaining cooling units show different magnetic fabric. Units 17, 23, 24 and 25, despite important variations in anisotropy (low for units 25 and high for units 23 and 24) and shape of ellipsoid (oblate in cooling unit 23, prolate in 24 and triaxial in 25) the k₃ axes show the same orientation, SW to SSW dipping around 45° and a very steady magnetic lineation azimuth NW nearly horizontal to sub horizontal. The magnetic mineralogy and magnetic fabric indicate that both the Icelandite and Rhyodacite cooling units the magmatic evolution during the shield stage of the entire Wai’anae volcano and that such growth was not affected by tectonic deformation. Full article

(This article belongs to the Special Issue Recent Advances of the Magnetic Evolution of Earth and Extraterrestrial Bodies: Insights from Geomagnetism, Rock Magnetism and Paleomagnetism)

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16 pages, 3087 KiB

Open AccessArticle

Influence of Relative Sea-Level Rise, Meteoric Water Infiltration and Rock Weathering on Giant Volcanic Landslides

by Julien Gargani

Geosciences 2023, 13(4), 113; https://doi.org/10.3390/geosciences13040113 - 06 Apr 2023

Cited by 3 | Viewed by 1710

Abstract

Recent studies have shown that giant landslides correlate with climatic variations. However, the precise processes involved in this phenomenon need to be better defined. This study investigates the causes of giant landslides using a modeling approach. Here, I show that the effect of [...] Read more.

Recent studies have shown that giant landslides correlate with climatic variations. However, the precise processes involved in this phenomenon need to be better defined. This study investigates the causes of giant landslides using a modeling approach. Here, I show that the effect of meteoric water infiltration could be distinguished from that of the sea level rise in triggering paleo-landslides. It is possible to identify the cause of coastal paleo-landslides based on the age of occurrence and comparison with climatic signals when glacial maxima are wetter than during interglacial periods, as in Polynesia and East Equatorial Africa, but not in other cases (Caribbean, Indonesia). The role of pore-pressure variations and sea water loading variations is discussed. The interaction between the relative sea level rise, pre-existing relief and deep weak structure due to the presence of highly weathered lavas may trigger the conditions for a large landslide. Highly weathered lavas have very low friction angles in volcanic islands. When volcanoes are still active, pressure fluctuations in the magma chamber caused by sea level lowering are expected to play a significant role in the destabilization of the relief. Competing processes in real cases make it difficult to distinguish between these processes. Full article

(This article belongs to the Topic Geotechnics for Hazard Mitigation)

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19 pages, 8946 KiB

Open AccessArticle

Assessing 40 Years of Flood Risk Evolution at the Micro-Scale Using an Innovative Modeling Approach: The Effects of Urbanization and Land Planning

by Tommaso Lazzarin, Andrea Defina and Daniele Pietro Viero

Geosciences 2023, 13(4), 112; https://doi.org/10.3390/geosciences13040112 - 06 Apr 2023

Cited by 4 | Viewed by 2494

Abstract

The present work is aimed at assessing the change in time of flood risk as a consequence of landscape modifications. The town of San Donà di Piave (Italy) is taken as a representative case study because, as most parts of the North Italy [...] Read more.

The present work is aimed at assessing the change in time of flood risk as a consequence of landscape modifications. The town of San Donà di Piave (Italy) is taken as a representative case study because, as most parts of the North Italy floodplains, it was strongly urbanized and anthropized in the last several decades. As a proxy for flood risk, we use flood damage to residential buildings. The analysis is carried out at the local scale, accounting for changes to single buildings; GIS data such as high-resolution topography, technical maps, and aerial images taken over time are used to track how the landscape evolves over time, both in terms of urbanized areas and of hydraulically relevant structures (e.g., embankments). Flood hazard is determined using a physics-based, finite element hydrodynamic code that models in a coupled way the flood routing within the Piave River, the formation of levee failures, and the flooding of adjacent areas. The expected flood damage to residential buildings is estimated using an innovative method, recently proposed in the literature, which allows estimating how the damage evolves during a single flood event. The decade-scale change in the expected flood damage reveals the detrimental effect of urbanization, with flood risk growing at the pace of a fraction of urbanized areas. The within-event time evolution of the flood damage, i.e., how it progresses in the course of past or recent flood events, reflects changes in the hydrodynamic process of flooding. The general methodology used in the present work can be viewed as a promising technique to analyze the effects on the flood risk of past landscape evolution and, more importantly, a valuable tool toward an improved, well-informed, and sustainable land planning. Full article

(This article belongs to the Special Issue Flood Hazard and Risk in Urban Areas)

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11 pages, 892 KiB

Open AccessCase Report

Physical- and Social-Based Rain Gauges—A Case Study on Urban Flood Detection

by Vitor Y. Hossaki, Wilson F. M. S. Seron, Rogério G. Negri, Luciana R. Londe, Lívia R. Tomás, Roberta B. Bacelar, Sidgley C. Andrade and Leonardo B. L. Santos

Geosciences 2023, 13(4), 111; https://doi.org/10.3390/geosciences13040111 - 06 Apr 2023

Viewed by 1925

Abstract

Floods are among the most frequent and costly rainfall-triggered disasters. In this context, geospatial content generated by non-professionals using geolocated systems offers the possibility of monitoring environmental events. This study shows a statistical correlation between in situsensors, radar, Twitter posts, and flooding events. [...] Read more.

Floods are among the most frequent and costly rainfall-triggered disasters. In this context, geospatial content generated by non-professionals using geolocated systems offers the possibility of monitoring environmental events. This study shows a statistical correlation between in situsensors, radar, Twitter posts, and flooding events. Furthermore, we observed in this study that flooding-related keywords are statistically more significant on flooding days than on non-flooding days and reinforce that Twitter can be employed as a complementary data source for flood management systems. Full article

(This article belongs to the Special Issue Flood Hazard and Risk in Urban Areas)

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18 pages, 8478 KiB

Open AccessArticle

Shallow Geothermal Potential of the Sant’Eufemia Plain (South Italy) for Heating and Cooling Systems: An Effective Renewable Solution in a Climate-Changing Society

by Giovanni Vespasiano, Giuseppe Cianflone, Marco Taussi, Rosanna De Rosa, Rocco Dominici and Carmine Apollaro

Geosciences 2023, 13(4), 110; https://doi.org/10.3390/geosciences13040110 - 05 Apr 2023

Cited by 3 | Viewed by 2261

Abstract

In this work, the shallow geothermal heat-exchange potential of a coastal plain in southern Italy, the Sant’Eufemia plain (Calabria region), was evaluated. Stratigraphic and hydrogeological data and thermophysical properties of the main geological formations of the area have been averaged over the first [...] Read more.

In this work, the shallow geothermal heat-exchange potential of a coastal plain in southern Italy, the Sant’Eufemia plain (Calabria region), was evaluated. Stratigraphic and hydrogeological data and thermophysical properties of the main geological formations of the area have been averaged over the first 100 m of subsoil to define the thermal conductivity, the specific heat extraction rates of the ground and the geothermal potential of the area (MWh·y⁻¹) for both cooling and heating modes. The investigation revealed that the crystalline bedrock and the saturated conditions of the sedimentary infill mainly control the heat-exchange potential. The range of the geothermal potential in the investigated Sant’Eufemia plain is 3.61–10.56 MWh·y⁻¹ and 3.72–11.47 MWh·y⁻¹ for heating and cooling purposes, respectively. The average depth drilled to supply a standard domestic power demand of 5.0 kW is ~90 m for heating and ~81 m for cooling modes. The different depth also drives the final drilling costs, which range from EUR 3200 to 8700 for the heating mode and from EUR 2800 to 7800 for the cooling mode. Finally, the mean values of drilling depth and costs for both heating and cooling modes are provided for the main municipalities and strategic sites. Full article

(This article belongs to the Special Issue Geochemical Characterization of Geothermal Systems: Multidisciplinary Approaches to Define Source Processes, Evolution and Environmental Issues)

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18 pages, 3247 KiB

Open AccessArticle

Subduction and Hydrogen Release: The Case of Bolivian Altiplano

by Isabelle Moretti, Patrice Baby, Paola Alvarez Zapata and Rosmar Villegas Mendoza

Geosciences 2023, 13(4), 109; https://doi.org/10.3390/geosciences13040109 - 04 Apr 2023

Cited by 3 | Viewed by 2657

Abstract

Natural hydrogen is known to be generated in the crust by water/rock interactions, especially the oxidation of iron-rich rock or radiolysis. However, other sources, especially deeper ones, exist. In the context of subduction, the dehydration of the slab, the destabilization of the NH [...] Read more.

Natural hydrogen is known to be generated in the crust by water/rock interactions, especially the oxidation of iron-rich rock or radiolysis. However, other sources, especially deeper ones, exist. In the context of subduction, the dehydration of the slab, the destabilization of the NH₄, and the hydration of the mantle wedge above the subducting lithosphere may generate H₂. We present here a compilation of the known gases in the central part of the Pacific subduction and the results of a first field acquisition dedicated to H₂ measurements in Bolivia between La Paz and South Lipez. Various zones have been studied: the emerging thrust faults of the western borders of the Eastern Cordillera, the Sajama area that corresponds to the western volcanic zone near the Chile border northward from the Uyuni Salar, and finally, the Altiplano-Puna Volcanic Complex in South Lipez. Soil gas measurement within and around the Salar itself was not fully conclusive. North of the Uyuni Salar, the gases are very rich in CO₂, enriched in N₂ and poor in H₂. On the opposite, southward, all the samples contain some H₂; the major gas is nitrogen, which may overpass 90% after air correction, and the CO₂ content is very limited. On the western border of the Cordillera, the δC13 isotope varies between −5 and −13‰_, and it is not surprisingly compatible with volcanic gas, as well as with asthenospheric CO₂. The methane content is close to 0, and only a few points reach 1%. The isotopes (−1‰) indicate an abiotic origin, and it is thus related to deep H₂ presence. The high steam flow in the geothermal area of South Lipez combined with the H₂ content in the water results in at least 1 ton of H₂ currently released per day from each well and may deserve an evaluation of its economic value. The nitrogen content, as in other subduction or paleo-subduction areas, questions the slab alteration. Full article

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28 pages, 6622 KiB

Open AccessArticle

Earthquake, Fire, and Water: Destruction Sequence Identified in an 8th Century Early Islamic Harbor Warehouse in Caesarea, Israel

by Charles J. Everhardt IV, Hendrik W. Dey, Uzi ‘Ad, Jacob Sharvit, Peter Gendelman, Joel Roskin, Lotem Robins, Roy Jaijel, Ofra Barkai and Beverly N. Goodman-Tchernov

Geosciences 2023, 13(4), 108; https://doi.org/10.3390/geosciences13040108 - 04 Apr 2023

Cited by 2 | Viewed by 2791

Abstract

An 8th century CE earthquake severely damaged inland cities across the southern-central Levant, but reported evidence of this earthquake along the coastline is scarce. In Caesarea Maritima, archaeologists have found contemporaneous anomalous sand and shelly layers within nearshore structures and interpreted them as [...] Read more.

An 8th century CE earthquake severely damaged inland cities across the southern-central Levant, but reported evidence of this earthquake along the coastline is scarce. In Caesarea Maritima, archaeologists have found contemporaneous anomalous sand and shelly layers within nearshore structures and interpreted them as construction fill, aeolian accumulation, or abandonment debris. Recently, similar sand deposits were exposed in a Roman-to-Islamic harbor-side warehouse. This presented the first opportunity to directly sample and systematically analyze in situ, undisturbed deposits in order to determine their origin and taphonomic (source and transport) history. Two sediment cores from the deposit as well as comparative reference samples from defined contexts were analyzed for grain size distribution, foraminifera (abundance/taphonomy), and relative age (POSL, archaeochronology). The results support the interpretation that the deposit was formed from the transport of offshore marine sediments during a high-energy inundation event, most likely a tsunami associated with the 749 CE earthquake. Full article

(This article belongs to the Special Issue Marine Geohazards)

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50 pages, 11165 KiB

Open AccessArticle

Vein Formation and Reopening in a Cooling Yet Intermittently Pressurized Hydrothermal System: The Single-Intrusion Tongchang Porphyry Cu Deposit

by Xuan Liu, Antonin Richard, Jacques Pironon and Brian G. Rusk

Geosciences 2023, 13(4), 107; https://doi.org/10.3390/geosciences13040107 - 01 Apr 2023

Cited by 1 | Viewed by 2815

Abstract

Porphyry deposits are the dominant sources of copper and major sources of several base and precious metals. They are commonly formed via the repeated emplacement of hydrous magmas and associated fluid exsolution. As a result, mineralized hydrothermal veins may undergo multiple deposition and [...] Read more.

Porphyry deposits are the dominant sources of copper and major sources of several base and precious metals. They are commonly formed via the repeated emplacement of hydrous magmas and associated fluid exsolution. As a result, mineralized hydrothermal veins may undergo multiple deposition and reopening processes that are not fully accounted for by existing fluid models. The Tongchang porphyry Cu deposit is a rare example of being related to a single intrusion. The simplicity in intrusive history provides an ideal starting point for studying fluid processes in more complex multi-intrusion porphyry systems. Detailed scanning electron microscope (SEM) cathodoluminescence imaging (CL) revealed rich microtextures in quartz and anhydrite that point to a fluid timeline encompassing early quartz deposition followed by fluid-aided dynamic recrystallization, which was succeeded by an intermediate stage of quartz dissolution and subsequent deposition, and ended with a late stage of continuous quartz deposition, brecciation, and fracturing. Vein reopening is more common than expected. Fifteen out of seventeen examined vein samples contained quartz and/or anhydrite that was older or younger than the vein age defined by vein sequences. Thermobarometry and solubility analysis suggests that the fluid events occurred in a general cooling path (from 650 °C to 250 °C), interspersed with two episodes of fluid pressurization. The first episode occurred at high-T (>500 °C), under lithostatic conditions alongside dynamic recrystallization, whereas the second one took place at a lower temperature (~400 °C), under lithostatic to hydrostatic transition conditions. The main episode of chalcopyrite veining took place subsequent to the second overpressure episode at temperatures of 380–300 °C. The results of this study reaffirm that thermal and hydraulic conditions are the main causative factors for vein reopening and growth in porphyry deposits. Full article

(This article belongs to the Special Issue Mineralogy and Geochemistry of Critical Metal-Bearing Mineral Deposits)

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26 pages, 6853 KiB

Open AccessArticle

Ocean–Ice Sheet Coupling in the Totten Glacier Area, East Antarctica: Analysis of the Feedbacks and Their Response to a Sudden Ocean Warming

by Guillian Van Achter, Thierry Fichefet, Hugues Goosse, Charles Pelletier, Konstanze Haubner and Frank Pattyn

Geosciences 2023, 13(4), 106; https://doi.org/10.3390/geosciences13040106 - 01 Apr 2023

Viewed by 1732

Abstract

We coupled together high-resolution versions of the ocean–sea ice model NEMO and the ice sheet model BISICLES configured to the Totten Glacier area and ran a series of simulations over the recent past (1995–2014) and under warming conditions (2081–2100; SSP4-4.5) with NEMO in [...] Read more.

We coupled together high-resolution versions of the ocean–sea ice model NEMO and the ice sheet model BISICLES configured to the Totten Glacier area and ran a series of simulations over the recent past (1995–2014) and under warming conditions (2081–2100; SSP4-4.5) with NEMO in stand-alone mode and with the coupled model to assess the effects of the coupling. During the recent past, the ocean–ice sheet coupling has increased the time-averaged value of the basal melt rate in both the Totten and Moscow University ice shelf cavities by

6.7 %

and

14.2 %

, respectively. The relationship between the changes in ice shelf thickness and ice shelf basal melt rate suggests that the effect of the coupling is not a linear response to the melt rate but rather a more complex response, driven partly by the dynamical component of the ice sheet model. The response of the ice sheet–ocean coupling due to the ocean warming is a 10% and 3% basal melt rate decrease in the Totten and Moscow University ice shelf cavities, respectively. This indicates that the ocean–ice sheet coupling under climate warming conditions dampens the basal melt rates. Our study highlights the importance of incorporating ocean–ice sheet coupling in climate simulations, even over short time periods. Full article

(This article belongs to the Section Cryosphere)

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17 pages, 5360 KiB

Open AccessArticle

Spatiotemporal Evolution of Ground Subsidence and Extensional Basin Bedrock Organization: An Application of Multitemporal Multi-Satellite SAR Interferometry

by Carlo Alberto Brunori and Federica Murgia

Geosciences 2023, 13(4), 105; https://doi.org/10.3390/geosciences13040105 - 01 Apr 2023

Cited by 1 | Viewed by 1420

Abstract

Since the early 1990s, the European (ESA) and Italian (ASI) space agencies have managed and distributed a huge amount of satellite-recorded SAR data to the research community and private industries. Moreover, the availability of advanced cloud computing services implementing different multi-temporal SAR interferometry [...] Read more.

Since the early 1990s, the European (ESA) and Italian (ASI) space agencies have managed and distributed a huge amount of satellite-recorded SAR data to the research community and private industries. Moreover, the availability of advanced cloud computing services implementing different multi-temporal SAR interferometry techniques allows the generation of deformation time series from massive SAR images. We exploit the information provided by a large PS dataset to determine the temporal trend of ground deformation and the relative deformation rate with millimetric accuracy to analyze the spatial and temporal distribution of land subsidence induced by water pumping from a deep confined aquifer in the Northern Valle Umbra Basin (Central Italy), exploiting 24 years of Permanent Scatterers—interferometric SAR data archives. The SAR images were acquired between 1992 and 2016 by satellites ERS1/2 and ENVISAT, the Sentinel 1 ESA missions and the COSMO-SkyMed ASI mission. We observed ground velocities and deformation geometries between 1992 and 2016, with displacements of more than 70 cm and velocities of up to 55 mm/yr. The results suggest that the shape and position of the surface ground displacement are controlled by the fault activity hidden under the valley deposits. Full article

(This article belongs to the Section Natural Hazards)

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22 pages, 5226 KiB

Open AccessArticle

Numerical Experiments for Surfactant Infiltration in the Vadose Zone to Demonstrate Concentration-Dependent Capillarity, Viscosity, and Sorption Characteristics

by Sebnem Boduroglu and Rashid Bashir

Geosciences 2023, 13(4), 104; https://doi.org/10.3390/geosciences13040104 - 01 Apr 2023

Viewed by 1602

Abstract

Surfactants (i.e., solutes that reduce the surface tension of water) exist in the subsurface either naturally or are introduced to the subsurface due to anthropogenic activities (e.g., agricultural purposes, environmental remediation strategies). Surfactant-induced changes in surface tension, contact angle, density, and viscosity alter [...] Read more.

Surfactants (i.e., solutes that reduce the surface tension of water) exist in the subsurface either naturally or are introduced to the subsurface due to anthropogenic activities (e.g., agricultural purposes, environmental remediation strategies). Surfactant-induced changes in surface tension, contact angle, density, and viscosity alter the water retention and conduction properties of the vadose zone. This research numerically investigates the effects of surfactants in the vadose zone by comparing the flow and transport of three different surfactant solutions, namely butanol, ethanol, and Triton X-100. For each surfactant case, surfactant-specific concentration-dependent surface tension, contact angle, density, and viscosity relationships were incorporated by modifying a finite element unsaturated flow and transport code. The modified code was used to simulate surfactant infiltration in the vadose zone at residual state under intermittent boundary conditions. The modelling results show that all three surfactant solutions led to unique and noteworthy differences in comparison to the infiltration of pure water containing a conservative tracer. Results indicate that surfactant infiltrations led to complex patterns with reduced vertical movement and enhanced horizontal spreading, which are a function of concentration-dependent surface tension, density, contact angle, viscosity and sorption characteristics. The findings of this research will help understanding the effects of surfactant presence in the subsurface on unsaturated flow and its possible links to future environmental problems. Full article

(This article belongs to the Collection New Advances in Geotechnical Engineering)

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20 pages, 8736 KiB

Open AccessArticle

Effect of Moisture Content on Subgrade Soils Resilient Modulus for Predicting Pavement Rutting

by Md Mostaqur Rahman, Sarah L. Gassman and Kazi Moinul Islam

Geosciences 2023, 13(4), 103; https://doi.org/10.3390/geosciences13040103 - 30 Mar 2023

Cited by 4 | Viewed by 3071

Abstract

The subgrade soil stiffness, which depends on the in-situ moisture content and soil index characteristics, is a key factor in pavement rutting. Due to variations in the compaction process used during construction and seasonal changes, the subgrade soil moisture content may deviate from [...] Read more.

The subgrade soil stiffness, which depends on the in-situ moisture content and soil index characteristics, is a key factor in pavement rutting. Due to variations in the compaction process used during construction and seasonal changes, the subgrade soil moisture content may deviate from the desired condition. The resilient modulus (M_R), an important parameter of the Mechanistic-Empirical (M-E) pavement design process, is used to specify the subgrade soil stiffness. Repeated load triaxial tests, which can be challenging and time-consuming to execute, are often used to determine M_R. As a result, correlations between M_R and more accessible stiffness metrics and index qualities are frequently used. California bearing ratio (CBR) and repeated load triaxial tests were carried out in this investigation. Soil specimens were fabricated at moisture levels that were both above and below the optimum moisture content (

w_{o p t}

). The results of the two tests were correlated, and statistical models were created to correlate the parameters of the generalized constitutive resilient modulus model with the characteristics of the soil index. Additionally, utilizing the M_R found for subgrade soils compacted at

w_{o p t}

and ±2%

w_{o p t}

, pavement rutting was analyzed for three base layer types. The results demonstrated that a laboratory-measured M_R (M_R(Lab)) decreases as the moisture content increases. Specimens compacted at −2%

w_{o p t}

showed higher M_R(Lab) than specimens compacted at

w_{o p t}

. Specimens compacted at +2%

w_{o p t}

showed lower M_R(Lab) than specimens compacted at

w_{o p t}

. Results also indicated that the M_R(Lab) predicted higher pavement rutting compared to field measured M_R (M_R(Lab)). If a stabilized aggregate foundation layer was employed instead of an untreated granular base, subgrade soil moisture condition showed a significant impact on rutting. Full article

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19 pages, 4524 KiB

Open AccessArticle

Effect of Curing Time on Lime-Stabilized Sandy Soil against Internal Erosion

by Shaziya Ahmed Banu and Mousa Fayiz Attom

Geosciences 2023, 13(4), 102; https://doi.org/10.3390/geosciences13040102 - 30 Mar 2023

Cited by 3 | Viewed by 1716

Abstract

One of the key challenges geotechnical engineers face is the failure of embankments due to internal soil erosion. Therefore, soil stabilization against internal erosion becomes necessary to prevent embankment failure. This paper aims to use lime to stabilize sandy soil against internal erosion. [...] Read more.

One of the key challenges geotechnical engineers face is the failure of embankments due to internal soil erosion. Therefore, soil stabilization against internal erosion becomes necessary to prevent embankment failure. This paper aims to use lime to stabilize sandy soil against internal erosion. Two types of sandy soil (poorly graded and well-graded) were treated with different percentages of lime (based on the dry weight of the soil) and curing times (1 day, 2 days, and 7 days). For poorly graded soil, the different lime percentages used were from 0.0% to 6.0% with an increment of 1% by dry weight of soil. While for well-graded soil, the lime percentages used were 0.0%, 1.0%, 2.0%, and 3.0% by dry weight of soil. The hole erosion test (HET) was utilized to analyze the erosion parameters of the soil samples. Results proved that lime is an effective soil stabilization agent against the internal erosion of sandy soil. Moreover, for optimum stabilization against internal erosion, poorly graded and well-graded sandy soil required about 5.0% and 3.0% of lime, respectively, with a curing time of 2 days. Significant reduction in erosion rate and improvement in the erosion rate index and critical erosion stress were observed at optimum soil stabilization. In addition, the results demonstrated that the curing time increases the erosion rate index and reduces soil erosion. Full article

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16 pages, 6047 KiB

Open AccessArticle

Estimate of Secondary Porosity from Surface Crossed Square Array Resistivity Measurements

by Manuel Joao Matias

Geosciences 2023, 13(4), 101; https://doi.org/10.3390/geosciences13040101 - 28 Mar 2023

Viewed by 1002

Abstract

The secondary porosity of rocks and formations plays an important role in water exploration and exploitation in crystalline rocks. Furthermore, cracks and voids are paths for contaminated fluid propagation and, thus, their location can be very important in environmental studies. Usually, secondary porosity [...] Read more.

The secondary porosity of rocks and formations plays an important role in water exploration and exploitation in crystalline rocks. Furthermore, cracks and voids are paths for contaminated fluid propagation and, thus, their location can be very important in environmental studies. Usually, secondary porosity is estimated from well logging observations, but some previous works have pointed out that azimuthal resistivity measurements and the square array can be used to estimate this parameter. Herein, the use of the square array and of the crossed square array will be investigated to estimate the secondary porosity. Thus, the analogue model and field resistivity data obtained with those arrays are discussed and interpreted. The analogue model simulates contacts between the isotropic and anisotropic media and between two different anisotropic media. The field data are from an area where steeply dipping formations prevail and contacts between the isotropic and anisotropic media are present. The calculated secondary porosity values are compared with the lateral changes in the resistivity and anisotropy, and pseudo sections are shown to aid the interpretation. In addition, 2D resistivity models for the field survey are produced to provide a better image and interpretation of the data. The overall results and limitations are discussed, and data acquisition procedures are proposed to optimize the field work. Full article

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16 pages, 7799 KiB

Open AccessArticle

Implementation of Surrogate Models for the Analysis of Slope Problems

by Amichai Mitelman, Beverly Yang and Davide Elmo

Geosciences 2023, 13(4), 99; https://doi.org/10.3390/geosciences13040099 - 26 Mar 2023

Cited by 3 | Viewed by 1348

Abstract

Numerical modeling is increasingly used to analyze practical rock engineering problems. The geological strength index (GSI) is a critical input for many rock engineering problems. However, no available method allows the quantification of GSI input parameters, and engineers must consider a range of [...] Read more.

Numerical modeling is increasingly used to analyze practical rock engineering problems. The geological strength index (GSI) is a critical input for many rock engineering problems. However, no available method allows the quantification of GSI input parameters, and engineers must consider a range of values. As projects progress, these ranges can be narrowed down. Machine learning (ML) algorithms have been coupled with numerical modeling to create surrogate models. The concept of surrogate models aligns well with the deductive nature of data availability in rock engineering projects. In this paper, we demonstrated the use of surrogate models to analyze two common rock slope stability problems: (1) determining the maximum stable depth of a vertical excavation and (2) determining the allowable angle of a slope with a fixed height. Compared with support vector machines and K-nearest algorithms, the random forest model performs best on a data set of 800 numerical models for the problems discussed in the paper. For all these models, regression-type models outperform classification models. Once the surrogate model is confirmed to preform accurately, instantaneous predictions of maximum excavation depth and slope angle can be achieved according to any range of input parameters. This capability is used to investigate the impact of narrowing GSI range estimation. Full article

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22 pages, 41867 KiB

Open AccessArticle

Analysing the Large-Scale Debris Flow Event in July 2022 in Horlachtal, Austria Using Remote Sensing and Measurement Data

by Jakob Rom, Florian Haas, Florentin Hofmeister, Fabian Fleischer, Moritz Altmann, Madlene Pfeiffer, Tobias Heckmann and Michael Becht

Geosciences 2023, 13(4), 100; https://doi.org/10.3390/geosciences13040100 - 26 Mar 2023

Cited by 1 | Viewed by 1731

Abstract

High-quality in situ measurements are essential for hazard assessment of debris flow events. However, precise data on debris flow triggering thresholds, accumulation volumes and spatial characteristics of large-scale events on catchment scale are scarce due to the rare occurrence of debris flows and [...] Read more.

High-quality in situ measurements are essential for hazard assessment of debris flow events. However, precise data on debris flow triggering thresholds, accumulation volumes and spatial characteristics of large-scale events on catchment scale are scarce due to the rare occurrence of debris flows and the challenges of acquiring accurate data for a larger area. In this study, we present quantitative analyses of a single extreme debris flow event in the Horlachtal, Austria, triggered by local high-intensity short-duration precipitation events on 20 and 23 July 2022. Pre- and post-event airborne LiDAR (light detection and ranging) data with a high spatial resolution reveal that 156 different debris flow processes were initiated during these events, with accumulation volumes of up to approximately 40,000 m³. The calculated debris flow deposition volumes also show a power-law relationship with the total amount of rainfall in the respective debris flow catchments. The spatial appearance of the debris flows shows a concentration of processes in a particular area rather than a uniform distribution, suggesting a local nature of the triggering event. This is further supported by the measurements from three meteorological stations and four discharge gauges within the study area. The gridded area-wide INCA (Integrated Nowcasting through Comprehensive Analysis) rainfall data further point to a local convective event on 20 July 2022, with a maximum rainfall intensity of 44 mm/h. Full article

(This article belongs to the Special Issue Remote Sensing Monitoring of Geomorphological Hazards)

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18 pages, 9832 KiB

Open AccessArticle

Toward a Plausible Methodology to Assess Rock Slope Instabilities at a Regional Scale

by Dimitris Sotiriadis, Nikolaos Klimis, Elisavet Isavela Koutsoupaki, Eleni Petala, Sotiris Valkaniotis, Maria Taftsoglou, Vasileios Margaris and Ioannis Dokas

Geosciences 2023, 13(4), 98; https://doi.org/10.3390/geosciences13040098 - 24 Mar 2023

Viewed by 1187

Abstract

Slope failures along road cuts and highways, occurring due to heavy rainfalls or earthquakes, pose significant threats to people, vehicles, and emergency plans. In the present study, a methodology to assess the stability of rock slopes at a regional scale is proposed using [...] Read more.

Slope failures along road cuts and highways, occurring due to heavy rainfalls or earthquakes, pose significant threats to people, vehicles, and emergency plans. In the present study, a methodology to assess the stability of rock slopes at a regional scale is proposed using a kinematic analysis and a probabilistic limit equilibrium analysis for plane sliding and wedge failure modes. The workflow adopted is described through its implementation along the main road network of the island of Thasos, located in northern Greece. On-site investigations and measurements along the island’s road network formed the basis of the present study. The results of the kinematic analysis showed that the joint sets, which were identified during the on-site investigations, formed critical intersections that could lead to wedge and plane sliding failures. The on-site measurements and the results of the kinematic analysis were utilized to perform limit equilibrium back-analyses at sites of identified failures due to the water pressure effects to probabilistically estimate the material strength properties of the joints. Subsequently, numerous limit equilibrium analyses were executed within a Monte Carlo simulation framework to produce representative fragility curves of rock slopes against plane sliding and wedge failures along the main road network, due to earthquake loading and water pressures. Full article

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29 pages, 5057 KiB

Open AccessArticle

Evolution of Coastal Subarctic Lakes in the Context of Climatic and Geological Changes and Human Occupation (North-Central Labrador, Canada)

by Camille Latourelle-Vigeant, Reinhard Pienitz and Najat Bhiry

Geosciences 2023, 13(4), 97; https://doi.org/10.3390/geosciences13040097 - 24 Mar 2023

Viewed by 2008

Abstract

Climate fluctuations and landscape evolution, with their associated impacts on northern coastal ecosystems, likely influenced human populations of Nunatsiavut who have inhabited the region for nearly 7000 years. As part of an interdisciplinary research initiative within the Nain Archipelago on the subarctic coast [...] Read more.

Climate fluctuations and landscape evolution, with their associated impacts on northern coastal ecosystems, likely influenced human populations of Nunatsiavut who have inhabited the region for nearly 7000 years. As part of an interdisciplinary research initiative within the Nain Archipelago on the subarctic coast of Labrador, this project sought to reconstruct the postglacial palaeoclimatic and palaeoenvironmental variability of Dog Island and document its impacts on the evolution of lakes located in the vicinity of significant archaeological sites. To address these questions, we analysed physical, geochemical, and biological indicators preserved in sediment cores of two lakes. Results from Oakes Bay West Lake revealed gradual acidification since ca. 4900 cal. yr BP, coherent with terrestrial vegetation development and/or neoglacial cooling, interrupted by periods of milder climatic conditions (ca. 4900–3640 cal. yr BP and ca. 1520 cal. yr BP—present) that favoured large sediment inputs. Evilik Lake revealed the classic sequence of isolation of the basin in three major phases in response to glacio-isostatic rebound. These complementary results allowed for the development of a local palaeoenvironmental framework that contributes to a better understanding of how landscape evolution and climate have influenced human societies through site availability and proximity to marine resources, and how, in turn, they impacted their immediate environment through activities, such as wood harvesting and its associated effects on nutrients and lake sediment inputs. Full article

(This article belongs to the Special Issue Arctic Geoarchaeology and Environmental Archaeology)

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