Upward continuation of potential fields has been used by geophysicists for many years as a means of smoothing data before interpretation. Despite its widespread use, no systematic investigations have been conducted regarding the optimal selection of the continuation height for noise suppression. In this paper, we provide a model study on the upward continuation height. We also consider the effect of the upward continuation height on the edge detection result. Through synthetic examples and a field example from the Tarija basin, South America, we assess how different continuation heights affect the results of the exponential transform of the tilt angle of the horizontal gradient (ETAHG). The results indicate that, when the upward continuation height is less than or equal to twice the grid spacing for gravity data, or less than or equal to five times the grid spacing for magnetic data, the results remain comparable to those at the observation plane. However, in the case of gravity data, the continuation height should not exceed five times the grid spacing, whereas for magnetic data, whose anomalies usually have a higher resolution, it should remain below ten times the grid spacing. The findings based on real data show that the ETAHG result for upward continuation data at 3.6 km is not only smooth but also accurately represents the geological structures of the Tarija basin. This map displays NW-SE trending lineaments, reflecting the dominant tectonic shortening direction during the Andean orogeny. In addition, many new structural features have been determined, providing a better understanding of the basin’s structural and tectonic framework.

Africa’s coastal regions face accelerating sea level rise compounded by climate variability. Here we analyze satellite altimetry data from 1993 to 2024 across African marine domains. The 2023–2024 El Niño produced the largest detrended sea level anomaly on record (27 mm), exceeding even the stronger 1997–1998 event. This exceptional response arose from ocean preconditioning: record-positive Indian Ocean Dipole, Atlantic Niño, and Tropical North Atlantic indices preceded and amplified El Niño forcing, while anomalous winds suppressed upwelling and record stratification trapped surface heat, quadrupling ocean heat content. Thermal expansion accounted for over 70

The African continent is characterized by a complex tectonic and geological history, with its current configuration shaped by the assemblage of Precambrian cratons and fragments delineated by Proterozoic and Paleozoic mobile belts. Knowledge of its lithospheric structure has primarily been derived from sparsely and irregularly distributed seismic surveys, limiting continent-wide analysis. To address this issue, we utilize satellite (e.g., GOCE, GRACE) and terrestrial gravity observations, integrated with lithospheric structure models, to compile a suite of gravity maps on a 5′ × 5′ geographical grid. The maps of the free-air, Bouguer, crust-stripped, mantle, lithosphere-stripped, and sub-lithospheric mantle gravity disturbances enable detailed interpretation of Africa's lithospheric architecture. Our methodology enhances traditional gravimetric studies by applying advanced corrections for topographic, bathymetric, sediment, crustal, and lithospheric mantle density heterogeneities, revealing deeper structural signatures. The free-air gravity map exhibits a signature of topographic and upper crustal density variations, with positive anomalies (+50 to +150 mGal) over elevated regions (e.g., Ethiopian Plateau) and negative anomalies (−50 to −150 mGal) over sedimentary basins (e.g., Congo Basin). The Bouguer gravity map highlights tectonic and volcanic features, reflecting crustal thickness variations, with isostatic equilibrium in cratons and disequilibrium along continental rifts like the East African Rift System (EARS). The crust-stripped gravity map mirrors Moho geometry, showing a stark contrast between thin oceanic and thick continental crust. The mantle gravity map exhibits a thermal signature, with gravity lows marking active divergent margins along the East and West Rift Systems and highs coinciding with cold, stable Archean cratons. Combined Bouguer and mantle gravity analyses confirm a non-collisional origin of mountain ranges along the EARS. Notably, the southern portion of the EARS lacks a clear thermal signature, suggesting distributed deformation at diffuse plate boundaries. These findings, alongside signatures of the African Superswell and the Congo Craton subsidence, provide new insights into Africa's geodynamic evolution, supporting future geophysical and resource exploration efforts.

The Cameroon Business City (CBC), Douala, is the Cameroon’s city which has the highest urbanisation and demographic growth rate. It is located on the Atlantic banks. Its geographic features are major indicators of various potential disasters, with natural (geological, hydrological, oceanographic, meteorological, biological) and/or anthropogenic (mainly industrial) drivers to be adequately managed. Disaster management is a tedious and complex process involving an important number of criteria to be considered and assessed. It includes a wide range of tasks such as forecasting, monitoring, evacuation, relief, search and rescue, rehabilitation and reconstruction, that can be grouped into three phases: pre-disaster, during disaster and post-disaster operations. Rather than preparing disaster response, this paper investigates the risk reduction by analysing the vulnerability of the CBC to disasters. It is a matter of predicting disasters by safeguarding timely preparedness on concerned institutions, government agencies, non-government organisations (NGOs) and citizens. The objective of this paper is to combine geographic information system (GIS), remote sensing (RS) and analytical hierarchy process (AHP) for disaster management in the CBC. A set of maps (with key role in disaster assessment) are derived and processed from satellite data. In addition to other thematic maps dealing with ecological, environmental, biophysical, and socioeconomic features, the aforementioned maps are processed as layers in a GIS environment using AHP to demarcate and classify the CBC by level of landslide risk and a gathering zone in case of a tsunami outbreak. Areas with high landslide risk cover 38

Geophysical surveys are a valuable tool for mapping and quantifying surface features for geothermal resource assessment. This paper combines the use of radiometric data and satellite images over the Damara division of June 2010 to January 2023 time series imagery of the high enthalpy geothermal potential of the southern part of the Central African Republic (CAR). The outcome from this research work is the demarcation of zones with a geothermal anomaly in the area. Based on spectral analysis using the aeromagnetic data provided from a compilation of satellite airborne measurements, and processing of imagery from the Landsat 8/9 data obtained, the Curie point depth, the geothermal gradient (GG) and the heat flow value have been plotted. The GG map shows a value of 50 degrees/km, and the heat flow reaches a value of 126 mWm-2. The time series analysis of LST for twenty years was performed. The results highlight the maximum LST anomaly (more than 61 degrees C) in the northwestern part of the Damara locality.

This study investigates sea level trends in the North Indian Ocean (NIO) from 2003 to 2024, quantifying the contributions of thermosteric, halosteric, and ocean mass components using satellite altimetry, observation-based gridded products, and GRACE gravimetry datasets. The NIO Sea level is rising at 4.83 ± 0.22 mm/yr, driven primarily by thermosteric sea level (2.21 ± 0.16 mm/yr) followed by ocean mass component (1.69 ± 0.09 mm/yr). Sub-basinal analysis reveals strong spatial heterogeneity, with the highest rates of sea level rise in the Western Bay of Bengal (5.19 ± 0.41 mm/yr) and the lowest in the Western Arabian Sea (4.29 ± 0.27 mm/yr). A distinct halosteric contrast exists, where freshening accelerates rise in the Bay of Bengal (up to 0.65 ± 0.08 mm/yr in the Eastern Bay), and increasing salinity suppresses it in the Arabian Sea (down to -1.12 ± 0.12 mm/yr in the western Arabian Sea). Furthermore, while western sub-basins are predominantly steric-driven, eastern sub-basins of Bay of Bengal and Equatorial Indian Ocean exhibit anomalously high GRACE-derived mass contributions (> 3 mm/yr), likely influenced by post-seismic crustal adjustments from the 2004 Sumatra-Andaman earthquake. Interannual variability closely tracks steric changes modulated by ENSO and the Indian Ocean Dipole (IOD), triggering basin-specific responses via wind anomalies and long-period waves. Further analysis of tropical SST indices reveals that the Western Tropical Indian Ocean SST index closely mirrors the spatial correlation structures of the Dipole Mode Index, and may serve as a useful indicator of regional sea level variability, particularly over the Equatorial Indian Ocean and Bay of Bengal. Ultimately, unlike the predominantly mass-driven global trends where both mass and steric contributions are of comparable magnitude, the NIO remains uniquely steric-dominated and the sea level budget leaves a residual of 0.98 mm/yr (~ 20% of the total trend), which, while comparable to uncertainties in individual components, highlights remaining challenges in fully closing the regional sea level budget.

Southwest Cameroon has long lacked detailed geological data, prompting an investigation into its geological and tectonic features through innovative edge detection techniques applied to gravity data. We employed various methods, including the Analytical Signal (AS), Tilt Angle (TDR), Total Horizontal Gradient of the Tilt Angle (TDR_THDR), and the Logistic Filter (IL) to delineate geological features that manifest as lineaments and contacts on gravity anomaly maps. Main findings of this study involve identification of key tectonic boundaries, notably the Kribi-Campo faults (KCF) and the Ebolowa pseudo-karstic circular network, the latter being mapped for the first time. This work reveals the continuity of the Ebolowa network and integrates connections such as the Mbilibekon and Mfuda caves, enhancing our understanding of the region's geological evolution. Additionally, we detailed the north-south extension of the KCF, which extends into both oceanic and terrestrial domains, aligning with the eastern margin of the Congo Craton. This finding suggests the fault system's role as a transition between the stable cratonic core and the dynamic mobile belts, necessitating a re-evaluation of regional tectonic models. To support our edge detection interpretations, we estimated Moho depths using gravity and seismic data, finding a Moho depth range between 34.5 km and 45.9 km, correlating with significant faulting and sedimentary features. This research enhances the understanding of subsurface structures in Southwestern Cameroon and provides a robust foundation for future geological and geophysical studies, emphasizing the critical interplay between surface and subsurface processes.

The tectonic and depositional history of the Hanoi basin is intricately shaped by the India-Eurasia collision, resulting in a complex subsurface structure that remains of significant interest for geophysical studies. In this research, classical and recent edge enhancement filters are applied to map subsurface features in the sediment-covered southern Hanoi basin. Additionally, the tilt-depth technique is employed to estimate the depth of subsurface structures in the study area. The interpretation revealed several subsurface structures, most of which have depths ranging from 0.9 km to 4 km. The subsurface features revealed by the enhancement filters show that the region’s structural trend is generally NW-SE, aligning with significant faults within the Red River fault zone, including the Song Chay and Song Lo. According to the tilt-depth estimates, the faults are identified at intermediate to deeper depths, reflecting geological displacements during the Oligocene and early Miocene that caused the Indochina geoblock to move about 700 km southeast along the Red River fault zone. Our detailed analysis also showed the Hanoi basin forms the landward extension of the Song Hong basin. The findings not only align with established tectonic features but also underscore the effectiveness of advanced filtering techniques, particularly the improved edge detector, in refining subsurface mapping within complex geological settings.

Orthometric heights are practically determined from levelling and gravity measurements by applying orthometric corrections to levelled height differences. Currently, Helmert’s definition of orthometric heights is mostly used, with the mean gravity computed only approximately from observed surface gravity by applying the Poincaré–Prey gravity reduction. In this study, we apply the state-of-the-art method for the orthometric height determination and demonstrate its practical applicability. The method utilizes advanced numerical procedures to account for the topographic relief and mass density variations, while adopting the Earth’s spherical approximation. The non-topographic contribution of masses inside the geoid is evaluated by solving geodetic boundary-values problems. We apply this method for the first time to practically determine the orthometric heights of levelling benchmarks from levelling and gravity measurements and digital terrain and rock density models. The results obtained after the readjustment of newly determined orthometric heights at the levelling network covering Hong Kong territories are compared with Helmert’s orthometric heights. This comparison revealed that errors in Helmert’s orthometric heights vary between −3.13 and 0.95 cm. Such errors are very significant when compared to accurate values of the cumulative orthometric correction between −1.88 and 0.84 cm. Moreover, large errors (up to 1 cm) already occur at levelling benchmarks at very low elevations (<100 m). These findings demonstrate that the accurate determination of orthometric heights is crucial, even for regions with moderately elevated topography.

This study provides an in-depth evaluation of sea level rise (SLR) and its varied effects across the coastal regions of southern Africa. Utilizing data collected between 1993 and 2022, we analyze SLR patterns alongside land subsidence phenomena, based on observations from 10 strategically located tide gauges and X-TRACK satellite altimetry datasets. To ensure greater accuracy, the Coastal Altimetry Approach was adopted to refine nearshore measurements. Findings indicate that in areas such as Cape Town, sea-level rise rates reach around 6.3 mm/year, which is nearly twice the current global average of 3.3 mm/year. The interaction between rapid sea-level rise and subsidence rates surpassing 2.2 mm/year presents significant threats to coastal communities, critical infrastructure, and natural ecosystems. Moreover, the study highlights how seismic activity contributes to coastal dynamics, illustrating the role of earthquake-induced subsidence in magnifying the impacts of SLR. By incorporating seismic factors into the analysis, a more comprehensive understanding of the interplay between natural and human-induced drivers of sea-level variability is achieved. Additionally, the study examines the broader effects of SLR on Africa’s culturally and historically important coastal heritage sites, emphasizing the urgent need for proactive coastal management and climate adaptation efforts.

In the equatorial Atlantic Ocean, the Mid-Atlantic Ridge is offset by a set of major transform fault systems, including the Romanche, Chain, Charcot, St. Paul, Doldrums and Vema faults, which remain relatively poorly understood due to the lack of detailed geophysical and geological studies. This study aims to analyze in detail satellite gravity data of the Equatorial Atlantic Ridge (EAR) to improve our understanding of its geological setting. To achieve this, we use the tilt angle of the horizontal gradient, the horizontal gradient of the second tilt angle, the balanced horizontal gradient, and the improved tilt angle of the horizontal gradient methods to map the lineaments of the area, while the depth of density sources is computed using the Euler deconvolution algorithm. The findings demonstrate the dominance of the ENE-WSW oriented trend, and the gravity sources are in the depth range of from 1.8 to 8 km. These findings are not only in agreement with known discordant and fracture zones, but also provide information on newly identified boundaries in the EAR. (c) 2025 COSPAR. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

The understanding of the factors influencing the active interaction and coalescence of intrarift fault segments in extending continental regions is limited. The 2009 Mw6.0 Karonga earthquake occurred in the westernmost portion of the Northern Malawi Rift, which hosts clustered intrarift faulting. The event ruptured the strongly coalesced southern segment of the St. Mary Fault (sSMF), and subsequently, moderate-magnitude events localized on poorly -coalesced segments that define the northern continuation of the fault. To investigate the role of coseismic stress redistribution on interacting faults, we explore the slip distribution of the 2009 event with realistic 3D strike-variable fault geometries, and compute coseismic Coulomb stress changes around the sSMF and neighboring faults. The results suggest that the down-dip intersections of the sSMF with the neighboring faults partition strain in a way that directs most of the deformation to >5 km depths. Additionally, the coseismic stress changes from the 2009 earthquake promoted interactions between the sSMF and adjoining northern segments of the fault at shallow (<5 km) depths, indicating that upper-crustal hard-linkage is underway in the poorly coalesced en-echelon sections of the northern segment. These results demonstrate how coseismic static stress transfer between evolving intrarift fault systems drive fault linkage over a single seismic cycle. Over successive slip events, such stress transfer processes may accelerate the linkage and coalescence of contiguous intrarift fault segments, amalgamate and deepen sub-basins along-strike, and promote across-rift basin compartmentalization. This process is relevant for fault coalescence over multi-seismic cycles, progressive maturation of rift basins, and transitions from juvenile continental rifting to the development of margins where break-up can initialize.

This study presents a comprehensive investigation of the complex dynamics of sea-level rise (SLR) and its multiple impacts on coastal regions in southern Africa. We meticulously analyse trends and patterns in SLR and subsidence rates using a wealth of data from 1993 to 2022, including observations from a network of 10 reliable tide gauges and XTRACK data processed using the Coastal Altimetry Approach to minimise the shortcomings of conventional coastal altimetry data. Our results show that sea level rise in coastal areas of South Africa, such as Cape Town (6.3 mm/yr), is almost double the global average (3.3 mm/yr). This alarming rate of SLR, coupled with a subsidence rate of more than 2.2 mm/yr, poses a significant and immediate threat to coastal communities, infrastructure and ecosystems. Our research also highlights the impact of seismic activity on coastal dynamics, further exacerbating the challenges posed by SLR. By incorporating the influence of earthquakes on subsidence, we provide a more nuanced understanding of the complex interplay of natural and anthropogenic factors contributing to SLR in the region. In addition, our research sheds light on the wider implications of SLR for some of Africa’s most iconic and culturally significant heritage sites, highlighting the urgent need for proactive coastal management and adaptation strategies.

Sea-level rise poses a significant threat to Africa’s vital coastal ecosystems and the livelihoods of its growing populations. Here we analyze 31 years of satellite altimetry data to quantify sea-level change across Africa’s Large Marine Ecosystems, vast ocean regions of high biological productivity. The rate of rise has accelerated markedly to 4.34 mm/yr since 2010, over four times the 1990s rate. This is primarily driven by two factors: an increase in ocean mass from melting ice sheets accounts for over 80% of the total rise, with the remainder reflecting the expansion of warming ocean water. Regional rates are fastest in the Red Sea and Guinea Current, while increased salinity suppresses the trend in the Mediterranean. 2023 was particularly severe, with record-high sea levels across nearly 40% of Africa’s surrounding ocean. This uneven rise intensifies risks for over 50 million coastal residents, underscoring the urgent need for region-specific adaptation.

Hydrogeophysical parameters of the ground play a vital role in heat transfer of ground source heat pump (GSHP) systems. Then, the investigation of the ground is necessary for the design and planning of GSHPs. This paper deals with investigations of Hydrogeophysical parameters of GSHP systems in Cameroon. Eighty-four drillings with the average deep of forty-seven meters have been performed in the Far North region of Cameroun in order to get hydrogeological and hydro geophysical characteristics of ground for shallow energy utilization. The results of geological study, vertical electrical sounding, pumping test, thermophysical properties, groundwater property and well data could help to understand better the heat transfer of borehole heat exchanger (BHE) and geo localization of potential GSHP in residentials of Logone et Chari, Cameroon. Closed systems of GSHP could be installed in the study area.

The Gulf of Guinea (GoG) is highly vulnerable to sea level rise, with projections indicating a significant increase in permanently inundated land by 2100, ranging from 1,458.1 to 4,331.7 km2. This study evaluates the severity of potential coastal inundation in the GoG by comparing sea level rise projections from eight reliable CMIP6 models with historical sea surface height (SSH) data from 1993 to 2015 and current onshore topography. Eight model simulations were selected based on their accuracy in reproducing sea level variability in the Tropical Atlantic and the GoG, and their consistency in reflecting the one-month connection lag between equatorial-driven waves and Kelvin Coastal Trapped Waves (CTWs) along the GoG, critical for predicting regional ocean dynamics. Our findings indicate that this connection lag will remain consistent over time. Under high-emission scenarios, up to 95% of coastal areas could be inundated, potentially displacing 2 million people posing a socio-economic shock, given the region’s low GDP and heavy reliance on fisheries. The loss of cultural heritage and livelihoods further compounds the challenges. These findings emphasize the urgent need for targeted adaptation strategies and robust early warning systems, in line with the UN’s Sustainable Development Goals (SDGs), particularly SDG 13 (Climate Action) and SDG 14 (Life Below Water). This study offers a precise and regionally relevant assessment of future risks, providing a foundation for informed policy interventions to mitigate the impacts of climate change and protect vulnerable communities in the GoG.

The West Cameroon region, characterized by a diverse geomorphology of highlands and plains resulting from tectonic processes across different geological ages, has been extensively explored for natural resources. Recognizing the significance of its tectonic and magmatic features associated with seismic and volcanic activity, this study focuses on geodynamic investigations of the Cameroon Volcanic Line (CVL). Despite previous efforts, detailed structural geophysical studies of the West Cameroon domain have proven inconclusive, prompting a comprehensive structural reinterpretation. Utilizing the high-resolution SGG-UGM-2 satellite gravity model and innovative processing techniques, including the horizontal gradient of a modified tilt (HGSTDR), the balanced horizontal gradient (BHG), the tilt of the horizontal gradient (TAHG), the improvised horizontal gradient tilt angle (impTAHG), and the Tilt Depth method, our research aims to enhance the interpretational quality of tectonic lineaments. By separating regional and residual anomalies in the Bouguer gravity map and applying a combination of filters to delineate geological units, the BHG filter emerges as a robust tool that highlights subsurface edges without generating false features. This approach unveils previously undetected NNW-SSE-oriented lineaments, confirming the presence of deep fractures and faults in Bafoussam, Nkongsamba, and along the Benue Trough, corroborated by newly discovered NNW-SSW trending lineaments. The study suggests that the region’s topography is overcompensated by deep mountain roots and compressive tectonism. Digitizing the BHG filter produces a structural map, revealing predominant NE trends in identified geological margins, including NNE-SSW, N-S, NW-SE, E-W, and NE-SW directions. Geological contacts between granite and high-grade gneiss are indicated by NNW-SSE and NNE-SSW trending lineaments along the Benue Trough. These results contribute significantly to the understanding of the tectonic setting of the West Cameroon Domain.

We utilized a high-resolution tailored gravity dataset to investigate the geological structure beneath the Southern Benue Trough of Nigeria and along the Cameroon Volcanic Line (CVL). The tailored gravity data was obtained by applying a stochastic combination technique to integrate global gravity field model, terrestrial gravity data, and residual gravity data over the study area. We then carried out gravity techniques to compile the Bouguer gravity map and to estimate the crustal thickness. To obtain suitable estimates of the reference depth and density contrast of the Moho interface, we fitted the gravimetrically determined Moho geometry to the seismic estimates by minimizing the Root-Mean-Square of their differences. A minimum RMS of 3.6 km at a reference depth of 26 km and a density contrast of 450 kgm(-3) was achieved over the study area. Our results reveal a dense magmatic feature criss-crossing the central portion of the study area. This phenomenon led to a thinning of the crust and formation of various geological structures, mainly at the southern end. We could see a very thick sedimentary cover within some of these structures possibly occasioned by compressional and extensional tectonic forces acting at the southwest end. Our study reveals that these compacted sedimentary covers could be important habitats for mineralization. We have also been able to refine and depict the lateral extent of the crustal architecture at a fine scale using our tailored gravity dataset. We concluded that the tectonic events beneath the study area are complex and point to several geophysical factors earlier revealed in published studies. However, a narrowing of two or more conjugate plates (margins) propelled by an upward force may have primarily led to the upward displacement of some of the magmas in-between those plates forming the intrusive rocks.