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

Las fallas y pliegues recientes y activos de la parte centro-oriental de las Zonas Internas de la Cordillera Bética

The most recent tectonic structures of the central-eastern Internal Zones of the Betic Cordillera (from 3.1ºW to 1.7ºW and to the south of 37.525ºN) include fault and folds developed from the Late Miocene onwards, which are related to N-S/NW-SE directed continental collision and moderate thickening of a crust that is relatively hot at depth. In this setting, E-W to WSW-ENE folds, with locally associated E-W transpressive right-lateral and reverse faults, favoured the emersion of the northern Alborán basin palaeomargin and the progressive intramontane basin disconnection. The NNE-SSW to NE-SW trending regional left-lateral Palomares and Carboneras fault zones are dominant structures in the easternmost part of the cordillera. In addition, NW-SE to WNWESE trending normal and oblique-slip normal faults are widespread. The collision is still active and continues to drive active folds and faults, some probably being the likely source of moderate-sized earthquakes. The Campo de Dalías and surrounding sectors, deformed by active ENE-WSW folds and NW-SE to WNW-ESE oblique-slip normal faults, are probably the sites with the largest concentration of significant earthquakes during recent years. Moderate-magnitude earthquakes (Mw 5.0 to 6.5) have occurred there at fairly regular intervals, in 1804, 1910, and 1994. Toward the east, NW-SE trending normal faults extending from Almería to the Tabernas basin deform the Quaternary rocks with associated moderate seismicity (the 2002 Gergal Mw 4.7 earthquake, and possibly the 1894 Nacimiento earthquake, felt with intensity VII). In the Sorbas-Vera basin, the Palomares fault zone is also responsible for moderate-sized earthquakes (1518 Vera earthquake). In the Almanzora corridor, NW-SE to WNW-ESE trending Lúcar-Somontín faults also could be considered one of the possible source of moderate-magnitude seismicity (1932 Lúcar, Mw 4.8 earthquake felt with intensity VIII). Toward the east, between Albox and Partaloa, several small reverse faults and associated compressive structures deform Quaternary alluvial and fluvial sediments. Although some of these folds reveal a slow and progressive deformation from the Middle Pleistocene onwards, some of these reverse fault segments that deform the western Huércal-Overa basin could host the 1972 NW Partaloa, mbLg 4.8 earthquake, felt with intensity VII.Las estructuras tectónicas más recientes que deforman la parte centro-oriental de las Zonas Internas de Cordillera Bética (entre 3.1º y 1.7ºO y al sur de 37.525ºN) son fallas y pliegues que comenzaron a formarse aproximadamente en el Mioceno superior en un contexto de colisión continental N-S/NO-SE y moderado engrosamiento cortical. En este marco tectónico, pliegues y fallas transpresivas dextras e inversas de direcciones E-O/OSO-ENE favorecieron la emersión del borde norte de la paleocuenca de Alborán y la progresiva desconexión de pequeñas cuencas intramontañosas. Además, comenzaron a formarse las grandes zonas de falla de Palomares y Carboneras, con direcciones NNE-SSO y NE-SO respectivamente y movimientos sinistros, que también han condicionado la evolución de la Cordillera Bética oriental desde el Mioceno superior. Algunas fallas con salto normal/normal-oblicuo y trazas NO-SE/ONO-ESE también se han desarrollado ampliamente en toda la zona de estudio. La colisión, aún activa, permite que algunos pliegues y fallas continúen propagándose en la actualidad, eventualmente causando terremotos con magnitudes moderadas. El Campo de Dalías y los sectores adyacentes, deformados por pliegues activos de direcciones ENE-OSO y fallas NO-SE/ONOESE normales-oblicuas, probablemente representan la zona con mayor concentración de terremotos importantes (Mw 5.0-6.5) con eventos recurrentes en 1804, 1910 y 1994. Al este del Campo de Dalías, una amplia zona de falla normal se extiende en dirección NO-SE desde Almería hasta la cuenca de Tabernas. Esta zona de falla muestra evidencias de funcionamiento durante el Cuaternario y tiene sismicidad moderada asociada a su terminación septentrional (el terremoto de Gergal en 2002 con Mw 4.7; y posiblemente el terremoto de Nacimiento en 1894 con intensidad VII). La zona de falla de Palomares es también responsable de terremotos moderados en la Cuenca de Sorbas-Vera (terremoto de Vera en 1518). En la parte central del corredor del Almanzora, alguno de los segmentos de falla normal que se extienden entre Lúcar y Somontín podría ser responsable del terremoto de Lúcar, en 1932 (Mw 4.8 e intensidad VIII). Al este, entre Albox y Partaloa, se han descrito fallas inversas y pliegues asociados que deforman sedimentos cuaternarios. Aunque algunas de estas estructuras muestran evidencias de funcionamiento lento y progresivo durante el Cuaternario, el terremoto de Partaloa en 1972 (mbLg 4.8 e intensidad VII) pudo ser causado por la actividad de cualquiera de estos segmentos de falla inversa que deforman la parte occidental de la cuenca de Huércal-Overa

Levelling Profiles and a GPS Network to Monitor the Active Folding and Faulting Deformation in the Campo de Dalias (Betic Cordillera, Southeastern Spain)

The Campo de Dalias is an area with relevant seismicity associated to the active tectonic deformations of the southern boundary of the Betic Cordillera. A non-permanent GPS network was installed to monitor, for the first time, the fault- and fold-related activity. In addition, two high precision levelling profiles were measured twice over a one-year period across the Balanegra Fault, one of the most active faults recognized in the area. The absence of significant movement of the main fault surface suggests seismogenic behaviour. The possible recurrence interval may be between 100 and 300 y. The repetitive GPS and high precision levelling monitoring of the fault surface during a long time period may help us to determine future fault behaviour with regard to the existence (or not) of a creep component, the accumulation of elastic deformation before faulting, and implications of the fold-fault relationship

A computer code for forward calculation and inversion of the H/V spectral ratio under the diffuse field assumption

During a quarter of a century, the main characteristics of the horizontal-to-vertical spectral ratio of ambient noise HVSRN have been extensively used for site effect assessment. In spite of the uncertainties about the optimum theoretical model to describe these observations, several schemes for inversion of the full HVSRN curve for near surface surveying have been developed over the last decade. In this work, a computer code for forward calculation of H/V spectra based on the diffuse field assumption (DFA) is presented and tested.It takes advantage of the recently stated connection between the HVSRN and the elastodynamic Green's function which arises from the ambient noise interferometry theory. The algorithm allows for (1) a natural calculation of the Green's functions imaginary parts by using suitable contour integrals in the complex wavenumber plane, and (2) separate calculation of the contributions of Rayleigh, Love, P-SV and SH waves as well. The stability of the algorithm at high frequencies is preserved by means of an adaptation of the Wang's orthonormalization method to the calculation of dispersion curves, surface-waves medium responses and contributions of body waves. This code has been combined with a variety of inversion methods to make up a powerful tool for passive seismic surveying.Comment: Published in Computers & Geosciences 97, 67-7

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

Gravimetric anomalies of the Guadix-Baza basin (Betic Cordillera, Spain)

Se han realizado los mapas gravimétricos de anomalías de Bouguer, regional y residual en la cuenca de Guadix-Baza (Cordillera Bética, sur de España) a partir de 3.648 nuevas estaciones de medida. El mapa de de anomalías residuales pretende ayudar a establecer las estructuras de la parte superior de la corteza y muestra claramente la existencia de varios depocentros importantes, en particular el del sector de Baza, controlados por fallas NNO-SSE en sus bordes orientales y occidentales, mientras que la zona de falla de Cádiz-Alicante los limita por el norte. Las facies sedimentarias y el espesor del relleno de la cuenca son congruentes con la posición de los depocentros: en el sector de Baza abundan en mayor proporción las facies lacustres que en los sectores de Guadix y Freila-Gorafe. La existencia de los depocentros está claramente determinada por la extensión ENE que afecta a la Cordillera.Gravimetric anomaly maps (Bouguer and residual) of the Guadix-Baza basin (Betic Cordillera, southern Spain) have been accomplished from the acquisition of 3648 new measurements. The residual anomaly map aims to evidence the features of the shallow crustal structures and clearly show the existence of several important depocentres (particularly that of the Baza sector) controlled by NNW-SSE faults in their eastern and western borders, while the northern borders are limited by the Cadiz-Alicante fault zone (s). The sedimentary facies and the thickness of the filling of the basin are consistent with the position of the depocentres: in the Baza area lacustrine facies are more abundant than in the depocentres of Guadix and Freila-Gorafe. The formation of the depocentres is clearly connected with the ENE extension affecting the whole cordillera.Este trabajo se ha realizado a través de la acción especial BTE2001-5230-E (Geometría del basamento de la cuenca de Guadix-Baza. Cordillera Bética) de la SEPCT.DGI, del Ministerio de Ciencia y Tecnología y de los proyectos CGL200401636/BTE, CGL2004-03333/BTE, CGL2006-06001, CSD2006-00041 y el grupo RNM 217 de la Junta de Andalucía

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

Combination of lumped hydrological and remote-sensing models to evaluate water resources in a semi-arid high altitude ungauged watershed of Sierra Nevada (Southern Spain)

Assessing water resources in high mountain semi-arid zones is essential to be able to manage and plan the use of these resources downstream where they are used. However, it is not easy to manage an unknown resource, a situation that is common in the vast majority of high mountain hydrological basins. In the present work, the discharge flow in an ungauged basin is estimated using the hydrological parameters of an HBV (Hydrologiska Byråns Vattenbalansavdelning) model calibrated in a “neighboring gauged basin”. The results of the hydrological simulation obtained in terms of average annual discharge are validated using the VI-ETo model. This model relates a simple hydrological balance to the discharge of the basin with the evaporation of the vegetal cover of the soil, and this to the SAVI index, which is obtained remotely by means of satellite images. The results of the modeling for both basins underscore the role of the underground discharge in the total discharge of the hydrological system. This is the result of the deglaciation process suffered by the high mountain areas of the Mediterranean arc. This process increases the infiltration capacity of the terrain, the recharge and therefore the discharge of the aquifers that make up the glacial and periglacial sediments that remain exposed on the surface as witnesses of what was the last glaciation.Grup d'Hidrologia Subterrànea, Universitat Politècnica de Catalunya, EspañaInstituto Andaluz de Investigación y Formación Agraria, Pesquera, Alimentaria y de la Producción Ecológica de Andalucía, EspañaUnidad de Granada, Instituto Geológico y Minero de España, EspañaUnidad de Zaragoza, Instituto Geológico y Minero de España, EspañaAgencia de Medio Ambiente y Agua de la Junta de Andalucía, EspañaDepartamento de Ciencias Geológicas, Universidad Católica del Norte, Chil

Integrating current and historical water chemistry data with long-term piezometric records to develop a regional-scale conceptual flow model: Las Salinas spring, Medina del Campo, Spain

Study region: Old Las Salinas spring in Medina del Campo, Duero river basin, central Spain. Study focus: Medina del Campo groundwater body (MCGWB) is a multilayer semiconfined aquifer subject to intensive pumping since the 1970’s, where the current existence of spas where there used to be traditional baths could confirm the existence of deep groundwater flow paths. The old spring of Las Salinas (OSLS) is a saline anomaly in an aquifer with predominance of CaCO3H waters whose occurrence has not yet been formally explained. Long-term geological, geophysical, hydrogeological and hydrochemical records were integrated and complemented with field work to clarify its existence. New hydrological insights for the region: Outcomes led to the conclusion that the hydrochemistry of the Olmedo and Palacio de las Salinas salt baths is associated with the existence of a major threshold in the impervious basement of the aquifer, which intercepted deep regional groundwater flow and caused upwelling to the surface under unperturbed conditions. These results allow for the development of a conceptual flow model at the regional scale that explains the changes in natural water chemistry that have been identified in recent decades

Integrating current and historical water chemistry data with long-term piezometric records to develop a regional-scale conceptual flow model: Las Salinas spring, Medina del Campo, Spain

20 p. - Supplementary material related to this article can be found, in the online version, at doi: https://doi.org/10.1016/j.ejrh.2021.100781.[EN] Study region Old Las Salinas spring in Medina del Campo, Duero river basin, central Spain. Study focus Medina del Campo groundwater body (MCGWB) is a multilayer semiconfined aquifer subject to intensive pumping since the 1970’s, where the current existence of spas where there used to be traditional baths could confirm the existence of deep groundwater flow paths. The old spring of Las Salinas (OSLS) is a saline anomaly in an aquifer with predominance of CaCO3H waters whose occurrence has not yet been formally explained. Long-term geological, geophysical, hydrogeological and hydrochemical records were integrated and complemented with field work to clarify its existence. New hydrological insights for the region Outcomes led to the conclusion that the hydrochemistry of the Olmedo and Palacio de las Salinas salt baths is associated with the existence of a major threshold in the impervious basement of the aquifer, which intercepted deep regional groundwater flow and caused upwelling to the surface under unperturbed conditions. These results allow for the development of a conceptual flow model at the regional scale that explains the changes in natural water chemistry that have been identified in recent decades.This research has received funding from the European Union H2020 Programme under Grant Agreement No. 730497 for the research project NAIAD-NAture Insurance value: Assessment and Demonstration.Peer reviewe