Structure of the Tabernas-Sorbas sedimentary basin by gravity and magnetic survey (Internal Zones, Eastern Betic Cordillera)

Se han determinado las anomalías gravimétricas y magnéticas en tres perfiles perpendiculares a la cuenca Tabernas-Sorbas (Zonas Internas, Cordillera Bética oriental). Los modelos gravimétricos muestran una morfología asimétrica del relleno sedimentario, con la mayor potencia de sedimentos próxima a su borde meridional. Los datos magnéticos revelan un dipolo asociado a mineralizaciones metálicas relacionadas con el contacto Alpujárride/ Nevado-Filábride. La evolución de la cuenca estuvo dominada por el desarrollo de un sinforme de dirección E-O a ENE-OSO y la actividad de fallas E-O a ESE-ONO dextro-inversas en su borde surGravity and total field magnetic anomaly data were obtained across three profiles in the Tabernas-Sorbas basin (Internal Zones, Eastern Betics). Gravity models show an asymmetric basin shape with the thicker sedimentary sequences close or attached to its southern edge.A magnetic dipole, located in the northern half of the profiles, is associated to ore bodies in the basement, linked to the Alpujárride / Nevado-Filábride contact. The basin evolution was controlled by the development of an E-W to ENE-WSW synform and the activity of E-W to ESE-WNW dextral-reverse faults in its southern boundar

Structure of the Campo de Dalías from gravimetric and seismic data

The analysis of new gravity data and multichannel seismic profiles of the Campo de Dalías give new insight about the main features of the deep structure. The progressive development since the Tortonian of folds determine the location of a large ENE-WSW elongated depocentre in a synform located at the central area, bordered by two antiforms situated respectively southwards, near the coast line, and northwards, in the Sierra de Gádor. Folding increase at depth and minor folds are also recognised in the limbs of the major folds. The faults in the region have relatively short slips and most of them have not clear expression in the geophysical dat

Fault overprinting and paleostresses in the Almanzora Corridor from the Tortonian to the Present (Betic Cordilleras)

The Almanzora Corridor in the Betic Cordilleras is affected by brittle deformations since the Tortonian. The analysis of fault overprinting shows a first group formed by a set of E-W dextral strike-slip faults, N-S leftlateral strike-slip faults and NW-SE normal faults compatible with a NW-SE shortening and an associated NE-SW extension. A second group corresponds to younger NW-SE normal faults, formed during NE-SW oblique extension to the Corridor, with an oblate stress ellipsoid that also reactivates, in some cases, previous faults. A more recent stress ellipsoid indicates extension, that is locally pluridirectional and reactivate previous fault surfaces, although horizontal striations have been overprinted in the Somontín fault, associated to a NW-SE recent shortening that is only locally registere

Structure of a complex carbonate aquifer by magnetic, gravity and TDEM prospecting in the Jaén area, Southern Spain

Knowledge of aquifer geometry is essential for efficient and sustainable groundwater management, particularly in carbonate aquifers due to uncertainties inherent to karstic systems. The geological structure and hydrogeological continuity of Los Chotos-Sazadilla-Los Nacimientos and La Serreta-Gante-Cabeza Montosa carbonate aquifers (Jaén; SE Spain) have been established through structural measurements, geophysical prospecting –magnetic, gravity and time-domain electromagnetics (TDEM)– and the study of piezometric levels. Yet the scarce hydrogeological data, the complexity of the tectonic structure and the presence of Plio-Quaternary rocks covering the highly permeable carbonate rocks make it difficult to establish a robust conceptual hydrogeological model of the aquifer. This study focuses on an area where hydrogeological disconnection between the two aquifers was traditionally assumed, given the diapiric emplacement of low permeable rocks between them. The new geophysical data demonstrate connection between aquifers that implies greater groundwater reserves than previously supposed. This field example supports the suitability of the combined use of electromagnetic methods with gravity and magnetic research that have been poorly combined up to recent times for hydrogeological studies.This work was financed by the Diputación Provincial de Jaén and through the project CGL-2010-21048, and the Junta de Andalucía group RNM148 and P09-RNM-5388

Structure of the Ugíjar Basin using gravity and magnetic data (Internal Zones, Central Betic Cordillera)

Nuevas medidas gravimétricas y magnéticas adquiridas en la Cuenca de Ugíjar contribuyen a determinar el espesor de su relleno sedimentario y las estructuras que deforman las rocas sedimentarias y el basamento. La combinación de los resultados gravimétricos con datos geológicos de superficie confirma la asimetría de la cuenca, condicionada por el funcionamiento, en su borde sur, de fallas ENE-OSO y componente dextrorsa-normal. En el borde norte, el techo del basamento profundiza con pendiente regional constante hacia el sur aunque hay estructuras tectónicas que deforman el relleno sedimentario. La existencia de dipolos magnéticos de pequeña entidad en el sector N está probablemente relacionada con mineralizaciones metálicas discontínuas asociadas al contacto Alpujárride/Nevado-FilábrideNew gravity and magnetic data reveal the geometry and thickness of the Ugíjar basin infill and provide additional information about the tectonic structures that deform both the basin and the basement rocks. As previous geological data suggested, the basin is asymmetric and highly conditioned by the activity of ENE-WSW trending faults with right-lateral/normal kinematics that are located in the southern border of the basin. At the northern boundary, the basement top dips smoothly southwards, although there are minor tectonic structures that deform up to the sedimentary infill. Magnetic dipoles have been detected in the northern part of the studied sector, probably associated with small and disperse metallic mineralizations deposited along the Alpujárride/Nevado-Filábride contac

Study of the freshwater-saltwater interface position en the Guadalfeo River mouth sector (Motril-Salobreña aquifer) with geophysical techniques and salinity logs

Se realizaron campañas geofísicas (Sondeos electromagnéticos en el dominio del tiempo y tomografía eléctrica) en el acuífero Motril-Salobreña para detectar la cuña salina que revelaron incertidumbres acerca de la posición exacta y la forma que presenta esta. En 2009, se perforó un sondeo de 250 m de profundidad cerca de la línea de costa. Los registros de salinidad en el sondeo mostraron un cambio de agua dulce a agua salobre que es considerado como el inicio el inicio de la interfaz agua dulce-agua salada. La información obtenida a través de los registros de salinidad y los métodos geofísicos se combinó para presentar una primera aproximación de la morfología del límite superior de la transición desde agua dulce a agua saladaSeveral geophysical surveys (time domain electromagnetic soundings and electrical resistivity tomography) have been carried out in Motril-Salobreña aquifer for detecting the saline wedge but there are uncertainties about the exact position and shape. In 2009 a 250 metres depth borehole was drilled near the coastline. Electrical water conductivity logs showed a fresh water-brackish water change that is considered as the beginning of the saltwater-freshwater interface. The information obtained with the logs and the geophysical methods has been combined and an approximation to the upper limit of the saltwater-freshwater interface shape is presente

Las acequias de careo de Sierra Nevada (sur de España), un sistema de recarga ancestral en acuíferos de alta montaña

En las partes altas de Sierra Nevada (sur de España) se realiza, desde época andalusí (Edad Media), un Sistema Integrado de Gestión del Agua Subterránea, en el que las acequias de careo constituyen un elemento clave. Estos canales excavados en el terreno están diseñados para recargar las aguas procedentes del deshielo, a lo largo de su recorrido y en distintas zonas concretas, donde hay una mayor permeabilidad del terreno. Una vez que el agua se infiltra en las partes altas de los valles, pasa a circular lentamente por los acuíferos superficiales y surge por ríos y manantiales situados a media ladera. En este trabajo se presentan los resultados conseguidos mediante el monitoreo e investigación hidrogeológica de una cuenca de 68 km2 (cuenca del río Bérchules), situada en Sierra Nevada, donde se aplica la técnica de careo. Los resultados conseguidos han permitido comprobar que el careo aplana el hidrograma de los ríos de alta montaña, reduciendo su componente nival y aumentando la subterránea. Además contribuye a mantener el caudal de los manantiales y los ecosistemas asociados a esta descarga. Su uso en otras zonas de alta montaña permitiría disponer de una excelente herramienta de adaptación al cambio climático.Instituto Geológico y Minero de España, EspañaUniversidad Politécnica de Cataluña, EspañaAgencia de Medio Ambiente y Agua de la Junta de Andalucía, EspañaUniversidad Pablo de Olavide, EspañaConsejería de Medio Ambiente y Ordenación del Territorio, Junta de Andalucía, EspañaPeer reviewe

Factors determining subsidence in urbanized floodplains: evidence from MT‐InSAR in Seville (southern Spain)

Major rivers have traditionally been linked with important human settlements throughout history. The growth of cities over recent river deposits makes necessary the use of multidisciplinary approaches to characterize the evolution of drainage networks in urbanized areas. Since under‐consolidated fluvial sediments are especially sensitive to compaction, their spatial distribution, thickness, and mechanical behavior must be studied. Here, we report on subsidence in the city of Seville (Southern Spain) between 2003 and 2010, through the analysis of the results obtained with the Multi‐Temporal InSAR (MT‐InSAR) technique. In addition, the temporal evolution of the subsidence is correlated with the rainfall, the river water column and the piezometric level. Finally, we characterize the geotechnical parameters of the fluvial sediments and calculate the theoretical settlement in the most representative sectors. Deformation maps clearly indicate that the spatial extent of subsidence is controlled by the distribution of under‐consolidated fine‐grained fluvial sediments at heights comprised in the range of river level variation. This is clearly evident at the western margin of the river and the surroundings of its tributaries, and differs from rainfall results as consequence of the anthropic regulation of the river. On the other hand, this influence is not detected at the eastern margin due to the shallow presence of coarse‐grain consolidated sediments of different terrace levels. The derived results prove valuable for implementing urban planning strategies, and the InSAR technique can therefore be considered as a complementary tool to help unravel the subsidence tendency of cities located over under‐consolidated fluvial deposits. Copyright © 2017 John Wiley & Sons, Ltd.Departamento de Geodinámica, Universidad de Granada, EspañaDepartamento de Ingeniería Cartográfica, Geodésica y Fotogrametría, Universidad de Jaén, EspañaCentro de Estudios Avanzados en Ciencias de la Tierra (CEACTierra), Universidad de Jaén, EspañaInstituto Andaluz de Ciencias de la Tierra, Consejo Superior de Investigaciones Científicas, EspañaInstituto Andaluz de Ciencias de la Tierra, Universidad de Granada, EspañaDepartamento de Ingeniería Civil, Universidad de Granada, EspañaInstitute for Systems and Computer Engineering, Technology and Science, Universidade de Trás‐os‐Montes e Alto Douro, PortugalInstituto Geológico y Minero de España, EspañaDepartment of Radar Technology, Netherlands Organisation for Applied Scientific Research, Países BajosGrupo de Investigación Microgeodesia Jaén, Universidad de Jaén, EspañaDepartment of Geoscience and Remote Sensing, Delft University of Technology, Países Bajo

Towards 3D databases and harmonized 3D models at IGME-CSIC

IGME-CSIC has a highly relevant geological and geophysical database that includes a continuous digital geological cartography at 1:50000; 1:200000 and 1:1000000 scales and a fair amount of geophysical data: gravity, magnetic, well-logs in tiff and LAS format, seismic lines in tiff and SEG-Y format, borehole and petrophysical data, together with other geophysical and geological studies. Since the 2004, an important effort has been done to undertake 3D geological and geophysical modelling ranging from local studies (mineral exploration or CO2 storage sites) to regional geology for a better understanding of the subsurface structure and its geodynamic evolution as a base for other studies on natural hazards or mineral resources. These studies were ¿stand alone¿ and now IGME is designing a new strategy. It includes the available data and models harmonization (stratigraphy sequences, structural interpretations, faults distribution, seismic velocity models, spatial distribution of physical properties such as density and magnetic susceptibility, workflows, methodologies, evaluation of uncertainties, visualization, etc.) to comply with the FAIR (Findable, Accessible, Interoperable and Reusable) data standardization. In this way, the new 3D models will be easily integrated and available from the databases. This strategy includes collaboration with the Bureau de Recherches Géologiques et Minières of France (BRGM) and Laboratório Nacional de Energia e Geologia of Portugal (LNEG) in order to harmonize the Spanish geological data and models with their neighbours across national borders. The first step is being done in the framework of GeoERA projects. Plain-language Summary IGME-CSIC owns a large database that includes a highly valuable geological and geophysical data and geophysical studies containing the interpretation of some of the data of Spain (onshore and offshore) Since 2004 the authors of this work have been working in 3D geological and geophysical modelling that includes local (mineral exploration or CO2 storage sites) and regional studies. The goal is to improve our understanding of the subsurface structures and processes as a base for deepening our knowledge in how the natural hazards occur, how to improve the exploration for mineral resources, etc. These studies were made ad hoc within different projects and now IGME-CSIC is designing a workflow to harmonize these models in order to comply with the FAIR (Findable, Accessible, Interoperable and Reusable) data standardization so the models will be available to being used beyond the initial objectives that generated their creation. This strategy includes collaboration with other European institutions like the Bureau de Recherches Géologiques et Minières of France (BRGM) and Laboratório Nacional de Energia e Geologia of Portugal (LNEG) in order to harmonize the models across national borders. The first step is already being done in the framework of the GeoERA projects

Geodetic fault slip rates on active faults in the Baza sub-Basin (SE Spain): Insights for seismic hazard assessment

One of the most significant parameters for seismic hazard assessment analyses is the fault slip rate. The combination of both geological (long-term) and geodetic (short-term) data offers a more complete characterization of the seismic potential of active faults. Moreover, geodetic data are also a helpful tool for the analysis of geodynamic processes. In this work, we present the results of a local GPS network from the Baza sub-Basin (SE Spain). This network, which includes six sites, was established in 2008 and has been observed for seven years. For the first time, we obtain short-term slip rates for the two active faults in this area. For the normal Baza Fault, we estimate slip rates ranging between 0.3 ± 0.3 mm/yr and 1.3 ± 0.4 mm/yr. For the strike-slip Galera Fault, we quantify the slip rate as 0.5 ± 0.3 mm/yr. Our GPS study shows a discrepancy for the Baza Fault between the short-term slip rates and previously reported long-term rates. This discrepancy indicates that the fault could be presently in a period with a displacement rate higher than the mean of the magnitude 6 seismic cycle. Moreover, the velocity vectors that we obtained also show the regional tectonic significance of the Baza Fault, as this structure accommodates one-third of the regional extension of the Central Betic Cordillera. Our GPS-related slip rates form the basis for future seismic hazard analysis in this area. Our results have further implications, as they indicate that the Baza and Galera Faults are kinematically coherent and they divide the Baza sub-Basin into two tectonic blocks. This points to a likely physical link between the Baza and Galera Faults; hence, a potential complex rupture involving both faults should be considered in future seismic hazard assessment studies.We acknowledge the comments of Editor Prof. Irina M. Artemieva and two anonymous reviewers, which significantly improved the quality of this paper. This research was funded by the Spanish Ministry of Science, Innovation and University (Research Projects: RTI2018-100737-BI00 and CGL2016-80687-R), the University of Alicante (Research Project: VIGROB053), the University of Jaén (PAIUJA 2019-2020 and Programa Operativo FEDER Andalucía 2014-2020 - call made by UJA 2018), the University of Granada (B-RNM-301-UGR18) and the Junta de Andalucía regional government (RNM148, RNM282, and RNM370 and P18-RT-3275 research groups). We thank all observers who collected the data of survey-mode GPS measurements