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his work focuses on two case studies carried out in Spain, where urban geophysics plays an important role in subsurface characterization. The application of geophysical methods in urban scenarios faces several challenges related to environmental noise (seismic or electromagnetic) or logistical constraints (lack of open space, complexity of instrumentation setup). In order to overcome these problems, research efforts are needed on both acquisition and processing aspects. The first case study presents the use of an innovative technology to acquire seismic data in the city of Granada. Distributed Acoustic Sensing (DAS) is based on the measurement of strain rate along a buried optical fiber that provides seismic measurements in a dense array of sensors. In our study, the fiber is a pre-existing underground telecommunications cable that crosses the city from northwest to southeast. We used 10 hours of ambient noise recordings to obtain subsurface reflection images that provide critical information for ground motion studies and seismic hazards in the metropolitan area. The second case study is located in the autonomous city of Melilla (North Africa). In this work, a gravimetric survey was carried out over the urban area with the aim of delineating the bedrock using 3D gravimetric inversion. We integrated the resulting geophysical model with surface geological observations, electrical resistivity tomography sections and borehole data to produce a 3D geological model of the city. Both studies highlight the suitability of geophysical information to complement the urban geological and geotechnical dataset to characterize and image the city underground.

[EN] The opening of the Scotia Arc resulted in the final breakup of the land bridge between South America and the Antarctic Peninsula. The South Orkney Microcontinent (SOM) constituted part of this former connection and it is now the largest continental block in the Southern Scotia Arc. We present the first 3D model of the SOM that, given its strategic position and characteristics, allows us to advance the knowledge of the tectonic processes involved in the development of the Scotia Arc. Due to the scarcity of reliable geological data, the initial approximation of the deep structure of the SOM was supported by the calculation of three main geological boundaries from geophysical data: the acoustic basement, the boundary of the magnetic anomaly source and the Moho depth. The 3D model was built, refined and validated by forward modeling and joint inversion of gravity and magnetic data. We have accurately defined the geometry of the sedimentary cover, determined the geometry of the intrusive igneous body causing the Pacific Margin Anomaly (PMA) and mapped the heterogeneity of the crustal thickness. These structural features show a clear relationship to each other and are consistent with an important E-W extension to the east of the SOM during early stages of the Scotia Arc formation, prior to the opening of the Powell Basin.

[EN] This contribution summarizes the geophysical research carried out to characterize the groundwater body (GWB) of Medina del Campo, located in the SE part of the Duero Basin, which corresponds to a multilayer detrital aquifer. The 3D model obtained displays the distribution of Miocene, Paleogene and Cretaceous sediments and the structure of the paleozoic basement in this sector of the basin. The 3D geological model was built with the Geomodeller software and comprises geological mapping, vertical electrical soundings, time domain electromanetic soundings and gravimetric data. An important methodological aspect of this work is the use of gravimetric forward modelling and gravimetric 3D inversion as main tools. The 3D geological model reveals that the subsurface of the Medina del Campo GWB is not homogeneous but is constituted by E-W to ENE-WSW depressions and highs mainly associated with pop-up and pop-down structures. In addition, NE-SW vertical faults developed depressions; like the Villorio-Alba fault with an associated displacement of 850 meters. The maximum depths of the basement are located to the SE part of Medina del Campo and south of Valladolid, where they reach values of more than 2000 m depth. In the surroundings of Medina del Campo, the basement has an EW trend and reaches about 1000 m depth. The Paleogene unit has a more constant sedimentary thickness in the center of the Basin with values of about 500 m, whereas the Miocene one shows greater Variations reaching up to 1500 m of thickness.This 3D geological model represents an important advance in the knowledge of the geometry of this GWB. It will have implications in future flow models of this part of the basin and in the definition of the resources and reserves of this GWB.

[EN] The environmental changes leading up to the first continent-wide glaciation of Antarctica during the Eocene-Oligocene Transition (EOT) are still not fully understood. Declining atmospheric CO2 concentrations and associated feedbacks have been invoked as underlying mechanisms, but the role of the coeval opening/deepening of Southern Ocean gateways (Drake Passage and Tasman Gateway), and subsequent changes in paleoceanography remain poorly understood. Evidence suggests both a temperate late Eocene and cooling before the EOT, both broadly coetaneous with a wide, supra-regional diagenetic event that resulted in green-clay (glaucony) formation in the marine realm around Antarctica (Houben et al., 2019; López-Quirós et al., 2019). Glaucony formation and evolution are driven by the activity of bacteria thriving in the organic-rich environment, a bio-geochemical system now considered to play a key role in the control of global ocean chemistry. Investigation of the reaction mechanisms throughout the formation of glaucony provides reliable information about (i) macro-scale environmental conditions, such as ocean transgression-regression cycles and ocean circulation changes, and (ii) the micro-scale sedimentary environment, such us sediment permeability, ion mobility and organic matter content – all of which are registered in the fabric and crystal-chemical characteristics of glaucony (e.g., López-Quirós et al., 2019; 2020; 2023). In addition, K-Ar dating of glaucony has provided 40% of the absolute-age dates for the geological timescale of the past 250 Ma. Glaucony is thus an important tool to date depositional ages of sediments and to reconstruct paleoenvironmental conditions. In spite of all, the nature, depositional setting, paleoenvironmental implications and chronology of the late Eocene glaucony reported in diverse shallow-marine settings in the Southern Ocean are loosely constrained (López-Quirós et al., 2019). In this contribution we describe, for the first time

The opening of the Scotia Arc resulted in the final breakup of the land bridge between South America and the Antarctic Peninsula. The South Orkney Microcontinent (SOM) constituted part of this former connection and it is now the largest continental block in the Southern Scotia Arc. We present the first 3D model of the SOM that, given its strategic position and characteristics, allows us to advance the knowledge of the tectonic processes involved in the development of the Scotia Arc. Due to the scarcity of reliable geological data, the initial approximation of the deep structure of the SOM was supported by the calculation of three main geological boundaries from geophysical data: the acoustic basement, the boundary of the magnetic anomaly source and the Moho depth. The 3D model was built, refined and validated by forward modeling and joint inversion of gravity and magnetic data. We have accurately defined the geometry of the sedimentary cover, determined the geometry of the intrusive igneous body causing the Pacific Margin Anomaly (PMA) and mapped the heterogeneity of the crustal thickness. These structural features show a clear relationship to each other and are consistent with an important E-W extension to the east of the SOM during early stages of the Scotia Arc formation, prior to the opening of the Powell Basin.

[EN] The tectonic map at scale 1:1,750,000 presented in this work shows an update of the existing knowledge of the main tectonic and volcanic structures along the Iberian continental margins and abyssal plains. The morphotectonic trends around Iberia recorded superposed geodynamic processes linked to the opening of the North Atlantic Ocean since the Mesozoic and the evolution of the Mediterranean Sea during the Cenozoic, as well as the reactivation of Hercynian faults and the formation of new tectonic structures during the Alpine orogeny. This map is based on the interpretation of the digital bathymetric model and other geophysical data from our own studies, and those from other authors. The morphotectonic features in this map provides a basis for the recognition of the tectonic control at lithospheric plate scale and the establishment of potential tectonic and volcanic risk zones.

[EN] Five decades of intensive groundwater exploitation have brought important economic, social and environmental changes in Medina del Campo Groundwater Body (MCGWB). Declining piezometric levels have worsened water quality, increased the costs of water supply and abstraction, and drained connected wetlands and rivers. This chapter presents the different methods and tools developed to assess the impacts and effectiveness for adaptation to droughts of the selected NAS strategies in biophysical, economic and social terms. It follows the methodologies presented in Chaps. 4, 5 and 6. It also summarizes the approaches for integrating all these assessments, as well as the main conclusions and lessons learnt. Important progress has been achieved on understanding and modelling the aquifer-system dynamics and functioning. First, geological and geophysical data analysis, debugging and integration have provided a basis for constructing a set of geological models of the MCGWB. Second, water balance components need to be updated through a deeper analysis of the recharge and groundwater abstractions (pumping). Third, a trend analysis of critical groundwater-related ecosystem services (GRES) and piezometric levels points at groundwater abstraction reductions as the most effective measure for a widespread recovery of the groundwater levels and storage. Fifth, the proposed managed artificial recharge would have limited effects on the recovery of the surface water bodies and no effect on the groundwater bodies. Sixth, the environmental reconstruction from a sedimentary record of the main wetland bed (Lagunas Reales) provides a reference knowledge base to understand the system response to human and climate changes. Finally, different barriers for design and implementation of NAS strategies have been identified and evaluated. Particularly, the lack of effective interaction mechanisms among the different actors involved/interested in the process could play a key role in the future.

[EN] Seismic methods are commonly usedfor subsurface imaging and geological characterization. Two different types of methods can be distinguished basedon the origin of the seismic waves that are analyzed.Active seismic methods study the propagation of artificially generated elastic waves using a controlled seismic source to obtain subsurface information.In the last years, there has been an increase interest in the use of passive seismic methods, mainly based on ambient noise analysis, for subsurface studies since they do not imply the use of any active sources, reducing the logistical complexity of the surveys.

[EN] The geophysics line at the IGME began in 1927 as a Geophysics Sectiondedicated to subsurface exploration. During all this time, it has been developed in order to support and give expert service in all IGME’s activities both as a geological service and public research institution, as well as a research and development work itself. On the other hand, in recent years the IGME has promoted a line of research aimed at the characterization and 3D modeling of geological structures and formations, the development of dedicated software and the evolution and sophistication of computer equipment. The new scenario of incorporation of the IGME to the CSIC as a national reference center in the field of Earth Sciences has allowed the establishment of the GEOFSUB Research Group (Subsurface Geophysics and Geology). It is constituted by 21 members who had been collaborating regularly of the IGME former scientific-technic areas Geophysics and remote sensing (Área de Geofísica y Teledetección) and Subsurface geology and 3D geological modelling (Área de Geología del Subsuelo y Modelización Geológica 3D). Our main differentiating element is our extensive knowledge of geophysical and geological techniques, which allows us to characterize the subsoil in an optimal wa

[EN] The pilotSTRATEGY (2021-2026) is investigating geological CO2 storage sites in industrial regions to support development of large-scale carbon capture and storage (CCS). It is focused on deep saline aquifers–porous rock formations filled with brine several kilometres below ground – which promise a large capacity for storing captured CO2. The goal of the characterisation is to assess the site’s containment, injectivity, capacity, integrity, hydrodynamics, and monitorability in order to ensure safe and permanent storage of CO2. PilotSTRATEGY covers the initial stages of project development up to the pre-final investment decision (pre-FID), regulatory approval and permitting of storage, and applied on selected structures of Paris Basin in France, the Lusitanian Basin in Portugal and the Ebro Basin in Spain, and in lower detail, in West Macedonia in Greece and Upper Silesia in Poland.

[EN] The tectonic features included in this dataset were compiled for a tectonic map at scale 1:1,750,000. This work shows an update of the existing knowledge of the main tectonic and volcanic structures along the Iberian continental margins and abyssal plains. The morphotectonic trends around Iberia recorded superposed geodynamic processes linked to the opening of the North Atlantic Ocean since the Mesozoic and the evolution of the Mediterranean Sea during the Cenozoic, as well as the reactivation of Hercynian faults and the formation of new tectonic structures during the Alpine orogeny. The delineation of the different tectonic features included in the dataset is based on the interpretation of the digital bathymetric model and other geophysical data from our own studies, and those from other authors. Accompanying the dataset, a PDF document with the bibliographical references used is also included.

This work aims to understand the link between the seafloor morphology and sub-seafloor stratigraphy of the Eastern Bransfield Basin (EBB; Antarctic Peninsula) with the water masses circulation established since the opening of the basin at around 3.3 Ma. Bottom currents (contourite) features identified from swath bathymetry data and parametric echo-sounder profiles acquired in the DRAKE2018 and POWELL2020 cruises are correlated with published information about water masses circulation and hydrological data. The EBB is the easternmost sector of the Bransfield Strait, oriented SW-NE and bounded by the Antarctic Peninsula to the southeast and the South Shetland and Elephant islands to the north and northwest. Contourite features are identified based on their sedimentary stacking pattern and morphological characteristics. They locate at distinctive depth levels in the EBB. A large mounded drift has been identified in an intra-slope platform in the SE margin, at water depths of 1000-1500 m. It is 35 km long and 20 km wide and is bounded by erosional contourite moats. These features are interpreted to result from the southwestward flow of the East Basin Deep Water (EBDW) at intermediate depths, formed by a mix of water masses from the Weddell Sea. Plastered drifts topped by contourite terraces occupy depths of 1100-1200 m along the SE margin of the basin, and are related to the high-energy oceanographic regime formed at the transitional boundary between the EBDW and the East Bransfield Bottom Water (EBBW). Contourite features on the deep, flat seafloor of the EBB at 2000-2300 m water depth are also formed by the EBBW. Mounded contourite drifts prograde and thin towards the outer limits of the basin, where contourite moats are interbedded with mass transport deposits. These contourite features have been generated by the episodic entrance of bottom water masses from the Central Basin and their mix with deep water masses flowing from the NE. This work reveals the highly dynam

The southern Scotia Sea hosts several small oceanic basins developed through continental break-up and oceanic spreading during the Cenozoic. Ona Basin is the southwestern most basin of the Scotia Sea. It is bounded by several structural highs: the Shackleton Fracture Zone to the west, Terror Bank to the east, and the South Scotia Ridge to the south. The southern part of the basin is further divided in two sub-basins (the western and eastern Ona basins) separated by the submarine relief called Ona High. The Ona Basin is mainly affected by two major water masses, the deeper branch of the Antarctic Circumpolar Current flowing eastwards and a westward flowing branch of the Weddell Sea Deep Water (WSDW). Interaction between mass movements and contouritic processes are likely to occur as a consequence of the complex geologic, physiographic and oceanographic setting. A combined approach including geomorphological, stratigraphic and seismic analyses allows us to document, for the first time, the record of repeated large-scale submarine landslides in the western Ona Basin. A major morphological feature named as 'Ona Paleovalley' is genetically related to large-scale Middle Pleistocene to recent mass movements. Deposition of large-scale mass transport deposits (MTDs) formed a template which guided and fostered major valley incision during the Middle Pleistocene. The valley infill records channelized depositional periods with possible development of turbidites alternating with erosive events when sediments were evacuated basinwards. This morpho-sedimentary pattern is attributed to the interplay between tectonic events leading to gravitational processes and the channelized flow of the WSDW.

Highlights • Core-log-seismic correlation allows to assign ages to the Scotia Sea seismic record. • Major implications are derived on the relation between regional and global events. • The main stratigraphic events are much younger than previously proposed. • Three major phases for the regional oceanography are observed from late Miocene. • These phases appear to be closely linked to the Antarctic Ice Sheet dynamics. Scotia Sea and the Drake Passage is key towards understanding the development of modern oceanic circulation patterns and their implications for ice sheet growth and decay. The sedimentary record of the southern Scotia Sea basins documents the regional tectonic, oceanographic and climatic evolution since the Eocene. However, a lack of accurate age estimations has prevented the calibration of the reconstructed history. The upper sedimentary record of the Scotia Sea was scientifically drilled for the first time in 2019 during International Ocean Discovery Program (IODP) Expedition 382, recovering sediments down to ∼643 and 676 m below sea floor in the Dove and Pirie basins respectively. Here, we report newly acquired high resolution physical properties data and the first accurate age constraints for the seismic sequences of the upper sedimentary record of the Scotia Sea to the late Miocene. The drilled record contains four basin-wide reflectors – Reflector-c, -b, -a and -a' previously estimated to be ∼12.6 Ma, ∼6.4 Ma, ∼3.8 Ma and ∼2.6 Ma, respectively. By extrapolating our new Scotia Sea age model to previous morpho-structural and seismic-stratigraphic analyses of the wider region we found, however, that the four discontinuities drilled are much younger than previously thought. Reflector-c actually formed before 8.4 Ma, Reflector-b at ∼4.5/3.7 Ma, Reflector-a at ∼1.7 Ma, and Reflector-a' at ∼0.4 Ma. Our updated age model of these discontinuities has major implications for their correlation with regional tectonic, oceanographic and cryospheric events. Acco

Multibeam bathymetric imagery and acoustic sub-bottom profiles are used to reveal distribution patterns of sub-surface sedimentation in Dove Basin (Scotia Sea). The goals of the study are to determine the imprint of the inflow of deep Antarctic water masses from the Weddell Sea into the Scotia Sea, to establish the factors driving the styles of contourite deposition and to discern the relative contribution of alongslope versus downslope processes to the construction of the uppermost late Quaternary sedimentary record in the basin. The most significant morpho-sedimentary features in Dove Basin are linked to contouritic processes and to mass movements. Plastered drifts on the flanks of the basin constitute the most common contouritic deposits. Basement-controlled drifts on top of structural elevations are common along the central ridge, the central basin plain and scattered along the basin flanks. Sheeted drifts occur on top of adjacent banks or are restricted to the deep basin. In contrast, mounded drifts are poorly represented in Dove basin. A laterally extensive contouritic channel runs along the central ridge. Contouritic channels are also identified in the upper parts of the lateral banks and slopes. Numerous slide scars along the upper parts of the slopes evolve downslope into semitransparent lens-shaped bodies, with occasional development of across-slope channels. Semitransparent lenses occur intercalated within stratified deposits in the slopes of the basin, in the central ridge and in the deepest basin plain. The spatial arrangement of contouritic morphologies points to the influence of the water column structure and the basin physiography. In the eastern sub-basin, two different fractions (lower and upper) of Weddell Sea Deep Water (WSDW) leave an imprint on contourite deposits owing to the sloping interface between the two fractions. Contouritic influence is more subdued in the western sub-basin, and limited to the imprint of the lower WSDW. The upper parts

The variability of sedimentation patterns and processes driven by late Quaternary glacial-interglacial paleoclimatic and paleoceanographic changes are investigated in Ona Basin, southwestern Scotia Sea. The interest of this area lies in the fact that the nearby Antarctic Peninsula has recorded extreme climatic variability, and the Drake Passage-Scotia Sea oceanic domain is influenced by two major Southern Ocean water masses, the eastward-flowing Antarctic Circumpolar Current (ACC) and the westward-flowing Weddell Sea Deep Water (WSDW). These goals are achieved through the examination of a grid of very high-resolution sub-bottom profiles and two gravity cores collected in Ona Basin. Multi-proxy data derived from the gravity cores include C-derived ages, descriptions of sedimentary units and diatom assemblages, and continuous logging of physical properties and micro-XRF core scanning. The sub-surface seismic stratigraphy is composed of four seismic units (U4 to U1) with a dominant sub-parallel configuration, with local occurrence of wavy facies and intercalations of transparent seismic facies. Additionally, four sedimentary units were recognized through sediment core analysis from bottom to top: Unit IV is composed of slightly bioturbated diatom-rich mud and silty mud with sparse ice-rafted debris (IRDs); Unit III is composed of gravelly silty to sandy mud with large amounts of IRDs; Unit II mostly contains bioturbated diatomaceous mud; and Unit I is composed of diatom-rich silty to sandy mud. The highest diatom abundances are found in Unit II, whereas highly variable abundances are found in Unit IV. The most common diatoms are Fragilariopsis kerguelensis and Chaetoceros subg. Hyalochaete. Overall, these characteristics document a change in the depositional style from terrigenous during the Last Glacial Maximum (LGM) to hemipelagic sedimentation during the deglaciation. The high-resolution seismic stratigraphy analysis reveals significant fluctuations in the regional

Multibeam bathymetric imagery and acoustic sub-bottom profiles are used to reveal distribution patterns of sub-surface sedimentation in Dove Basin (Scotia Sea). The goals of the study are to determine the imprint of the inflow of deep Antarctic water masses from the Weddell Sea into the Scotia Sea, to establish the factors driving the styles of contourite deposition and to discern the relative contribution of alongslope versus downslope processes to the construction of the uppermost late Quaternary sedimentary record in the basin. The most significant morpho-sedimentary features in Dove Basin are linked to contouritic processes and to mass movements. Plastered drifts on the flanks of the basin constitute the most common contouritic deposits. Basement-controlled drifts on top of structural elevations are common along the central ridge, the central basin plain and scattered along the basin flanks. Sheeted drifts occur on top of adjacent banks or are restricted to the deep basin. In contrast, mounded drifts are poorly represented in Dove basin. A laterally extensive contouritic channel runs along the central ridge. Contouritic channels are also identified in the upper parts of the lateral banks and slopes. Numerous slide scars along the upper parts of the slopes evolve downslope into semitransparent lens-shaped bodies, with occasional development of across-slope channels. Semitransparent lenses occur intercalated within stratified deposits in the slopes of the basin, in the central ridge and in the deepest basin plain. The spatial arrangement of contouritic morphologies points to the influence of the water column structure and the basin physiography. In the eastern sub-basin, two different fractions (lower and upper) of Weddell Sea Deep Water (WSDW) leave an imprint on contourite deposits owing to the sloping interface between the two fractions. Contouritic influence is more subdued in the western sub-basin, and limited to the imprint of the lower WSDW. The upper parts

Distributed acoustic sensing (DAS) is an innovative technology with a great potential for acquiring seismic datasets in urban areas. In this work, we will check the suitability of a DAS dataset acquired in the city of Granada (Spain) for retrieving subsurface reflectivity from ambient noise. The fiber-optic is a pre-existing underground telecommunication cable that crosses the city from Northwest to Southeast. We use 10 hours recording of strain rate in a selected sector of the cable to obtain seismic reflections using the autocorrelation method. The results are constrained by the autocorrelation result of a 24 hours record at a three-component seismic station near the targeted sector. Some cable segments do not show clear reflectivity patterns due to a lack of useful energy in these regions that may be related to a loose ground coupling. However, autocorrelation stacks in some other segments are consistent with the results obtained with the seismic station. This work highlights the usefulness of recording strain rate along with urban fiber-optic cables and the use of ambient noise techniques such as autocorrelation. The retrieved reflectivity information can be used to complete 3D geological models, which are essential for urban development projects.