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[EN] This paper analyses the performance of SAR-based results to support emergency management operations during the volcanic crisis of La Palma island. Tajogaite eruption began on September 19th 2021 affecting a high populated area and the surrounding farmland, used for different agricultural purposes. SAR datasets obtained from Sentinel-1, COSMO-SkyMED, PAZ-TerraSAR-X and Capella satellites, were processed to calculate amplitude, coherence and differential interferograms. These results have permitted to map the morphology of the volcanic cone, the evolution of lava flows and the regional displacements. The comparison of the results obtained with the different satellites has been useful to understand their performance during an emergency scenario triggered by a volcanic eruption. COSMO-SkyMED has provided the most useful information for the analysis of the cone morphology and the lava flows. Sentinel-1 showed the best performance for regional displacements monitoring, whereas PAZ results was the second best option for all the retrieved products.

[EN] Tiwanaku is an Archaeological World Heritage Site, located at an elevation of 3,885 m.a.s.l., south of Lake Titicaca (La Paz), in the high plateau region of Bolivia. The present paper reports the actions carried out in the frame of the project: “Preservacion y conservacion de Tiwanaku y la piramide de Akapana, Bolivia”. The consultancy was requested by UNESCO Office in Quito, following previous activities conducted since 2010 and directly by the CIAAAT. During the first mission in the archaeological site of Tiwanaku (from 9 to 16 May 2016), an interdisciplinary team, carried out the preliminary diagnosis concerning the geotechnical processes affecting the Akapana pyramid. After that, another filed mission was carried out in order to implement a general master plan of actions aimed at the conservation and risk reduction of the whole pyramid. For this scope during 2017 two different field survey were carried out. Main scope of the activities was: (i) prepare and develop a long term executive full proposal conservation project for the Pyramid; (ii) implement a Terrestrial Laser Scanning (TLS) survey in order to produce a very detail topographical setting of the whole pyramid; (iii) collect core drilling samples in the Akapana pyramid for laboratory analysis; (iv) perform stability analysis 3D Model; (v) identify mitigation measures for a test site. After the summer 2017 field mission, the main topographical outcomes of the TLS survey were elaborated, incorporated and adopted for the implementation a pilot project of mitigation measures. Final design has been implemented along the east flank of the pyramid, and support was given to local authorities and workers during all the mitigation measures implementation.

[EN] This paper presents a multiscale methodology to perform successful geo-hazards assessment in the context of Cultural Heritage. The methodology, defined in the European PROTHEGO project, has been applied to the Alhambra case study. Alhambra is an important Word Heritage site located in Andalusia, Spain. The site is prone to suffer flood, earthquake and landslide phenomena. The proposed multiscale methodology leans on new remote monitoring and modelling technics that not entail aesthetic and functional impacts on the site. For large-scale monitoring, satellite remote sensing technology enables to detect and characterize spatiotemporal ground and structure deformation as a whole, with up to millimeter precision. For very local phenomena analysis, small-scale monitoring based on Terrestrial Laser Scanner and airborne drone digital photogrammetry surveys enables to detect erosion processes that affect the slopes of the citadel. Furthermore, numerical modelling enables geo-mechanical instabilities to be quantified at different scales. Large-scale modelling shows that the most dangerous slope is located at the San Pedro cliff site. Small-scale stability analysis in the San Pedro cliff shows that a slope failure, triggered by a possible earthquake scenario, could reach the wall foundations of the Alhambra citadel located 22 m behind it. Finally, very detailed small-scale modelling, using very precise digital elevation models, enables to track local instabilities and erosion phenomena. Such a multiscale, interdisciplinary approach is the most effective way to identify, assess and monitor risks, strengthening disaster preparedness at heritage property.

[EN] The island of Gran Canaria (Canary Islands, Spain) is characterized by a large variability of volcanic rocks reflecting its volcanic evolution. The geological map provided by Geological Survey of Spain at 1:25.000 scale shows more than 109 different lithologies and it is too complex for environmental and engineering purposes. This work presents a simplified geotechnical map with a small number of classes grouping up units with similar geotechnical behaviours. The lithologies were grouped using about 350 rock samples, collected in the seven major islands of the Archipelago. The geotechnical map was used to model rockfall hazard in the entire island of Gran Canaria, where rockfalls are an important threat. The rockfall map was validated with 128 rockfall events along the GC-200 road, located in the NW sector of Gran Canaria. About 96% of the events occurred along sections of the road where the number of expected trajectories is high or moderate.

Aquifer overexploitation can lead to the irreversible loss of groundwater storage caused by the compaction or consolidation of unconsolidated fine-grained sediments resulting in land subsidence. Advanced Differential SAR Interferometry (A-DINSAR) is particularly efficient to monitor progressive ground movements, making it an appropriate method to study depleting aquifers undergoing overexploitation and land subsidence. The Guadalentín River Basin (Murcia, Spain) is a widely recognized subsiding area that exhibits the highest rates of groundwater-related land subsidence recorded in Europe (>10 cm/yr). The basin covers an extension of more than 500 km2 and is underlain by an overexploited aquifer-system formed by two contiguous hydraulically connected units (Alto Guadalentín and Bajo Guadalentín). Although during the last years the piezometric levels have partially stabilized, the ongoing aquifer-system deformation is evident and significant, as revealed by the A-DInSAR analysis presented. In this work, we submit the first vertical and horizontal (E-W) decomposition results of the LOS velocity and displacement time series of the whole Guadalentín Basin obtained from two datasets of Sentinel-1 SAR acquisitions in ascending and descending modes. The images cover the period from 2015 to 2021 and they were processed using the Parallel Small BAseline Subset (P-SBAS) implemented by CNRIREA in the Geohazards Exploitation Platform (GEP) on-demand web tool, which is funded by the European Space Agency. The output ascending and descending measurement points of P-SBAS lie on the same regular grid, which is particularly suited for the geometrical decomposition. Time series displacements are compared to a permanent GNSS station located in the Bajo Guadalentín basin.

[EN] Within the framework of the IGME-CSIC Department of Geological Hazards and Climate Change, the OBTIER research group was created in July 2021 and currently has 22 members, including scientific and technical staff, as well as young people with contracts linked to competitive national and international research projects. The main objective of the group is to provide society with scientific information, methods, tools and solutions to mitigate the impact of geohazards and the effects of Climate Change. OBTIER is currently leading 6 competitive projects (4 European and 2 national), as well as several projects in agreement with other national and international administrations. It is an active member of the EuroGeoSurveys Earth Observation Expert Group and the ASGMI Geological Hazards Group. OBTIER offers society a wide range of capabilities on: earthquakes, tsunamis, landslides, land subsidence, volcanic eruptions, droughts and floods. In 2021, the group published an article in Science entitled: Mapping the global threat of land subsidence with significant media coverage around the world.

[EN] Detecting and monitoring slope movements is essential to better understand their causes and mitigate their adverse consequences. Satellite radar interferometry (InSAR) techniques allow to generate deformation maps at high resolution (both spatial and temporal), especially since 2014, when the European Space Agency's Sentinel-1 mission (6-day revisit frequency) became operational. The application of InSAR is, however, constrained by a number of limitations. The main one relates to the inability of the technique to measure rapid deformation phenomena. In the case of Sentinel-1, for example, the maximum measurable deformation rate (along the satellite line of sight) is about 0.85 m/year. In this context, the application of digital photogrammetry (SfM) orthoimagery correlation techniques constitutes a directly applicable alternative for the remote monitoring of rapid slope movements. Moreover, whereas the application of InSAR monitoring techniques in densely vegetated areas is often impractical given the decorrelation produced by strong changes in the vegetation cover, the application of SfM monitoring techniques allows more effective analyses to be conducted in areas with abundant vegetation.

The island of Gran Canaria (Canary Islands, Spain) is characterized by a large variability of volcanic rocks reflecting its volcanic evolution. The geological map provided by Geological Survey of Spain at 1:25.000 scale shows more than 109 different lithologies and it is too complex for environmental and engineering purposes. This work presents a simplified geotechnical map with a small number of classes grouping up units with similar geotechnical behaviours. The lithologies were grouped using about 350 rock samples, collected in the seven major islands of the Archipelago. The geotechnical map was used to model rockfall hazard in the entire island of Gran Canaria, where rockfalls are an important threat. The rockfall map was validated with 128 rockfall events along the GC-200 road, located in the NW sector of Gran Canaria. About 96% of the events occurred along sections of the road where the number of expected trajectories is high or moderate.

Interpretation of land subsidence time-series to understand the evolution of the phenomenon and the existing relationships between triggers and measured displacements is a great challenge. Continuous wavelet transform (CWT) is a powerful signal processing method mainly suitable for the analysis of individual nonstationary time-series. CWT expands time-series into the time-frequency space allowing identification of localized nonstationary periodicities. Complementarily, Cross Wavelet Transform (XWT) and Wavelet Coherence (WTC) methods allow the comparison of two time-series that may be expected to be related in order to identify regions in the time-frequency domain that exhibit large common cross-power and wavelet coherence, respectively, and therefore are evocative of causality. In this work we use CWT, XWT and WTC to analyze piezometric and InSAR (interferometric synthetic aperture radar) time-series from the Tertiary aquifer of Madrid (Spain) to illustrate their capabilities for interpreting land subsidence and piezometric time-series information.

A novel methodological approach to calibrate and validate three-dimensional (3D) finite element (FE) groundwater flow and geomechanical models has been implemented using Advanced Differential Interferometric SAR (A-DInSAR) data. In particular, we show how A-DInSAR data can be effectively used to (1) constrain the model set-up in evaluating the areal influence of the wellfield and (2) characterise the aquifer system, specifically the storage coefficient values, which represents a fundamental step in managing groundwater resources. The procedure has been tested to reconstruct the surface vertical and horizontal movements caused by the Manzanares-Jarama wellfield located northwest of Madrid (Spain). The wellfield was used to supply freshwater during major droughts over the period between 1994 and 2010. Previous A-DInSAR outcomes obtained by ERS-1/2 and ENVISAT acquisitions clearly revealed the seasonality of the land displacements associated to the withdrawal and recovery cycles that characterized the wellfield development. A time-lag of about one month, which is in the order of the time span between two SAR acquisitions, between the hydraulic head changes and the displacements has been detected in this site by a wavelet analysis of A-DInSAR and piezometer time series. The negligible delay between the forcing factor and the system response and the complete subsidence recovery when piezometric head recovers supported the understanding of a minor role played by the pore pressure propagation within clay layers and the almost perfectly elastic behavior of the system (viscosity is negligible), respectively. The developed geomechanical model satisfactorily reproduces the pumping-induced deformations with a Root Mean Square Error (RMSE) between observed and simulated land displacements in the order of 0.1-0.3 mm. The results give insights about the approach benefits in deeply understanding the spatio-temporal aquifer-system response to the management of this strategic water r

The launch of the medium resolution Synthetic Aperture Radar (SAR) Sentinel-1 constellation in 2014 has allowed public and private organizations to introduce SAR interferometry (InSAR) products as a valuable option in their monitoring systems. The massive stacks of displacement data resulting from the processing of large C-B and radar images can be used to highlight temporal and spatial deformation anomalies, and their detailed analysis and postprocessing to generate operative products for final users. In this work, the wide-area mapping capability of Sentinel-1 was used in synergy with the COSMO-SkyMed high resolution SAR data to characterize ground subsidence affecting the urban fabric of the city of Pistoia (Tuscany Region, central Italy). Line of sight velocities were decomposed on vertical and E–W components, observing slight horizontal movements towards the center of the subsidence area. Vertical displacements and damage field surveys allowed for the calculation of the probability of damage depending on the displacement velocity by means of fragility curves. Finally, these data were translated to damage probability and potential loss maps. These products are useful for urban planning and geohazard management, focusing on the identification of the most hazardous areas on which to concentrate efforts and resources.

Two earth fissures appeared in Murcia province (southeastern Spain) after the flood occurred because of a heavy downpour on 28 September 2012. In this area, located within the Guadalentín Valley, up to 212 L m−2 was reported that day. More than 200 agricultural exploitations were destroyed by the flooding, with a devastating effect on many infrastructures, such as a main A-7 highway bridge that collapsed in this event. The earth fissures appeared after this flooding in the towns of Puerto Lumbreras and Totana. The first fissure showed a straight-line direction approximately parallel to the main geological structures of the Guadalentín Valley. The total length of the fissure was 400 m and was 2 to 3 m in depth. The soil in the fissure is classified as a low-plasticity silt with some sand and clay, ML, according to the Unified Soil Classification System. From the sieve and hydrometer tests, the percentage of silt in these samples was between 48 % and 68 %, the clay content between 12 % and 30 % and the sand content between 2 % and 40 %. The plasticity index was smaller than 9.2 for all the samples. To evaluate the piping and internal erosion susceptibility of the soil, pinhole, crumb and geochemical tests were done on the collected samples. A result of non-dispersive soil was obtained from crumb and pinhole tests. Nevertheless, the pH, sodium adsorption ratio and exchangeable sodium percentage tests showed that some samples could be affected by the dispersion of the soil. Also, the collapsible potential of the soil was studied, showing negative results for all the samples except for that collected at the southern end of the fissure, which showed a medium to high potential. Concerning the Totana fissure, it appeared with different branches and holes instead of as a rectilinear pattern. The total length of the fissure was 190 m, with the soil characterized as a silty soil. Lastly, INSAR data, GPS, GPR and land subsidence maps were used to study the possible origin of th

Advanced Differential Interferometric Synthetic Aperture Radar (A-DInSAR) techniques and 3-D groundwater flow and geomechanical models are integrated to improve our knowledge about the Tertiary detritic aquifer of Madrid (TDAM). In particular, the attention is focused on the Manzanares-Jarama well field, located to the northwest of Madrid, which experienced five cycles of extensive groundwater withdrawal followed by natural recovery, to cope with the droughts occurred in summer 1995, 1999, 2002, 2006, and 2009. Piezometric records and A-DInSAR data acquired by ERS-1/2 and ENVISAT satellites during the periods 1992–2000 and 2002–2010, respectively, have been used to calibrate the groundwater flow and the geomechanical models. A time-lag of about one month between the hydraulic head changes and the displacements of the land surface has been detected by a joint wavelet analysis of A-DInSAR and piezometer head time series. Overall, the results show the effectiveness of the proposed integrated approach composed of A-DInSAR and 3-D geomechanical model to characterize the aquifer-system response during and after the groundwater withdrawal.

Aquifer-systems have become a strategic source of fresh water in the present climatic conditions, especially under stress in arid regions like the Iberian Mediterranean Arc. Understanding the behavior of groundwater reservoirs is crucial to their well-management and mitigation of adverse consequences of overexploitation. In this work, we use space geodetic measurements from satellite interferometric synthetic aperture radar (InSAR) and Global Positioning System (GPS) data, covering the period 2011–2017, to predict and validate the ground surface displacement over the fastest subsiding basin due to groundwater withdrawal in Europe (>10 cm/year). The 2D decomposition of InSAR displacements from Cosmo-SkyMed and Sentinel-1 satellites allows us to detect horizontal deformation towards the basin center, with a maximum displacement of 1.5 cm/year. InSAR results were introduced in a newly developed methodology for aquifer system management to estimate unknown pumping rates for the 2012–2017 period. This study illustrates how the combination of InSAR data, groundwater flow and deformation models can be used to improve the aquifer-systems sustainable management.

Landslides, creep slow movements and rockfalls have been widely studied from modern times by using remote sensing, which goes back up to 20 years by using GPS and INSAR and almost 100 years by using aerial photographs. The use of ancient maps and even old paintings from the 19th century allow going back up to200 years. In this work, we introduce the use of lichenometry of wandering blocks to estimate the velocity of a landslide located at El Portalet (Central Pyrenees, Spain), by using these blocks (decametric size and limestone lithology) as time and spatial markers. To do this, we have used lichenometry to estimate the age of the blocks and determinate the runout distance traveled by the blocks detached from the source area, by geomorphologic markers. We have obtained the annual growth rate (GR) of the calcicolous lichen specie Aspicilia calcarea (Hoffm.) from cemeteries, historical buildings and infrastructures for the last 300 yrs. A lineal GR value of 0.45 mm/yr has been estimated. The oldest block was dated in 600 CE ± 40 yr. and the modernone in 1750 CE ±5 yr. The analysis of aerial orthophotos and field work of the study zone reveals two N- and S-oriented chutes in which wandering blocks were located: the North path (NP) and the South path (SP). Theinventory map had been carried out taking in account the wandering blocks disseminated close to 1 km in length from the source area. The lichenometry analysis yields that the block surface velocity varies from 0.3 m/yr to =0.97 m/yr for the NP and 0.2 to 0.88 m/yr for the SP. However, the behavior of both chutes is opposite. Whereas the NP accelerates during warm climate periods and decelerates in the cold ones, on the contrary, the SP velocity decelerated during Medieval Warm Period and accelerated during the Little Ice Age (LIA). Estimations of the block wandering during the Industrial Era are approximated. INSAR and GPS velocity during the last 20 yrs. shows 0.2 m/yr. Clinometers and thermometers in boreholes i

The Bàlitx area is located on the steep coastal side of the Tramuntana Range (Majorca), a mountainous region which was declared a World Heritage Site by UNESCO in 2011 in the cultural landscape category. The Bàlitx site was occupied by farming areas with dry stone constructions and water storing systems of both Roman and Islamic origin. The coastal landscape is characterised by a large fault escarpment of up to 260 m in height. Lateral spreading processes are favoured by local stratigraphy and tectonics in an energetic coastal dynamics scenario. Block spreading morphologies are identified along the escarpment, with large, rocky blocks of volumes up to 60 × 103 m3 moving very slowly until their collapse. Consequently, a thick and highly karstified breccia deposit is accumulated at the base of the scarp. The lowest, oldest breccia outcrop has been dated (Th/U), and an age of 82.5 ± 5.6 kyr was obtained, reflecting the time span this process has been active. Additionally, numerous geomorphological slope features are identified in the area: landslides, rockfalls, and, more specifically, long and deep cracks in the hanging wall block of the fault, which also reveal active lateral spreading processes. Coastal dynamics have been investigated by interpreting offshore geophysical studies, bathymetry data and borehole information to determine the role of wave energy in the stability of the slope. Additionally, 14 SAR images from the ALOS PALSAR satellite have been exploited for the present work, covering a period spanning from 2007 to 2010, an anomalous rainy period in the region. Images were processed using the Persistent Scattered Interferometry (PSI) technique. PSInSAR results reveal that the rate of movement for the Bàlitx lateral spreading is extremely low (− 5.2 mm/year on average), but major activity has been detected in the NE sector, where velocity rates can reach values of up to − 16 mm/year Coastal dynamics in the area can explain this, as a small island generates

The Bàlitx area is located on the steep coastal side of the Tramuntana Range (Majorca), a mountainous region which was declared a World Heritage Site by UNESCO in 2011 in the cultural landscape category. The Bàlitx site was occupied by farming areas with dry stone constructions and water storing systems of both Roman and Islamic origin. The coastal landscape is characterised by a large fault escarpment of up to 260 m in height. Lateral spreading processes are favoured by local stratigraphy and tectonics in an energetic coastal dynamics scenario. Block spreading morphologies are identified along the escarpment, with large, rocky blocks of volumes up to 60 × 103 m3 moving very slowly until their collapse. Consequently, a thick and highly karstified breccia deposit is accumulated at the base of the scarp. The lowest, oldest breccia outcrop has been dated (Th/U), and an age of 82.5 ± 5.6 kyr was obtained, reflecting the time span this process has been active. Additionally, numerous geomorphological slope features are identified in the area: landslides, rockfalls, and, more specifically, long and deep cracks in the hanging wall block of the fault, which also reveal active lateral spreading processes. Coastal dynamics have been investigated by interpreting offshore geophysical studies, bathymetry data and borehole information to determine the role of wave energy in the stability of the slope. Additionally, 14 SAR images from the ALOS PALSAR satellite have been exploited for the present work, covering a period spanning from 2007 to 2010, an anomalous rainy period in the region. Images were processed using the Persistent Scattered Interferometry (PSI) technique. PSInSAR results reveal that the rate of movement for the Bàlitx lateral spreading is extremely low (− 5.2 mm/year on average), but major activity has been detected in the NE sector, where velocity rates can reach values of up to − 16 mm/year Coastal dynamics in the area can explain this, as a small island generates

This paper presents an advanced 3D numerical methodology to reproduce the kinematics of slow active landslides, more precisely, to reproduce the nearly constant strain rate (secondary creep) and the acceleration/deceleration of the moving mass due to hydrological changes. For this purpose, finite element analyses are performed in a large area covering a long time-span (12 years), in order to exhibit different interacting slope movements. First, we perform a stability analysis using the shear strength reduction (SSR) technique with a Mohr-Coulomb failure criteria. It is done in order to compute factors of safety (FS) and to identify two different scenarios, the first one being stable (FS > 1) and the second one being unstable (FS < 1). In the studied test case, the Portalet landslide (Central Spanish Pyrenees), the first scenario corresponds to an initial stable configuration of the slope and the second one to an unstable excavated configuration. Second, taking the first scenario as an initial condition, a time-dependent analysis is performed using a coupled formulation to model solid skeleton and pore fluids interaction, and a simplified ground water model that takes into account daily rainfall intensity. In this case, a viscoplastic constitutive model based on Perzyna’s theory is applied to reproduce soil viscous behavior and the delayed creep deformation due to the excavation. The fluidity parameter is calibrated to reproduce displacements measured by the monitoring systems. Our results demonstrate that 3D analyses are preferable to 2D ones for reproducing in a more realistic way the slide behavior. After calibration, the proposed model is able to simulate successfully short- and medium-term predictions during stages of primary and secondary creep.

Groundwater resources are under stress in many regions of the world and the future water supply for many populations, particularly in the driest places on Earth, is threatened. Future climatic conditions and population growth are expected to intensify the problem. Understanding the factors that control groundwater storage variation is crucial to mitigate its adverse consequences. In this work, we apply satellite-based measurements of ground deformation over the Tertiary detritic aquifer of Madrid (TDAM), Central Spain, to infer the spatio-temporal evolution of water levels and estimate groundwater storage variations. Specifically, we use Persistent Scatterer Interferometry (PSI) data during the period 1992–2010 and piezometric time series on 19 well sites covering the period 1997–2010 to build groundwater level maps and quantify groundwater storage variations. Our results reveal that groundwater storage loss occurred in two different periods, 1992–1999 and 2005–2010 and was mainly concentrated in a region of ∼200 km2. The presence of more compressible materials in that region combined with a long continuous water extraction can explain this volumetric deficit. This study illustrates how the combination of PSI and piezometric data can be used to detect small aquifers affected by groundwater storage loss helping to improve their sustainable management.

La cuenca Alta del Guadalentín presenta una de las mayores tasas de subsidencia de Europa (>10 cm/año). Desde los años 60 el acuífero subyacente que alimenta parte de la agricultura del área de Lorca ha experimentado descensos piezométricos muy acusados, siendo declarado como sobreexplotado en 1987. La relación entre ambos fenómenos es uno de los principales objetivos del proyecto AQUARISK (Estudio de riesgos geológico-geotécnicos por explotación de acuíferos mediante técnicas espaciales y terrestres. Aplicaciones a estructuras e infraestructuras urbanas. ESP2013-47780-C2-2-R).Como parte de este proyecto se están utilizando los resultados de deformación superficial obtenidos mediante interferometría radar (DInSAR) junto con datos geológicos e hidrogeológicos. Para complementar y validar los resultados se ha llevado a cabo una campaña de nivelación en 2016 y la instalación de una estación GPS permanente. A partir de los primeros resultados se están desarrollando nuevos productos que interrelacionan las componentes superficial y subterránea: a) subdivisión de las formaciones del acuífero por características deformacionales y productos SAR, b) construcción de un modelo numérico de flujo para el acuífero entre 1960 y 2012 que usa el anterior producto, c) generación de modelos geomecánicos que reproduzcan las deformaciones que se presentan en la zona a partir de los cambios en el acuífero., Alto Guadalentín basin is affected by one of the greatest subsidence rate in Europe (>10 cm/year). Since the 1960s, the underlying aquifer system, which is used to irrigate the Lorca area, has presented a continuously declining water level, eventually being declared as overexploited in 1987. The relationship between both phenomena is one of the main goals of the AQUARISK project (Analysis of geological-geotechnical risks due to groundwater exploitation using space and terrestrial techniques. Application in urban structures and infrastructures. ESP2013-47780-C2-2-R). As part of this project, radar interferometry (DInSAR) measurements of the deformation field from 1992 to 2016, geological and hydrogeological data will be used. In order to complement and validate the results a levelling campaign was performed in 2016 and a permanent GPS station was installed. Using our preliminary results, new models and products interrelating surface and underground data are being developed, specifically: a) subdivision of the aquifer system layers based on deformational properties and SAR data, b) development of a hydrogeological flow model between 1960 and 2012 taking into account new descripted sublayers, c) development of geomechanical models reproducing surface deformation from water level changes.

El acuífero terciario detrítico de Madrid (ATDM) proporciona agua a Madrid, la ciudad más poblada de España (3,2 millones de habitantes en el área metropolitana). Entre 1991 y 2011 el acuífero experimentó cinco ciclos de extracción y recuperación de agua subterránea, asociados a dos periodos de sequía. En este estudio hemos analizado la deformación del terreno producida por la extracción de agua subterránea y su posterior recuperación. Para ello se han analizado datos de interferometría radar (InSAR) y datos piezométricos en 19 pozos de extracción durante el periodo 1997-2010. La correlación entre la deformación del terreno y la piezometría en los pozos analizados es superior al 85% y, por lo tanto, es posible modelizar esta relación asumiendo un comportamiento elástico del acuífero. A partir de los modelos elásticos hemos: i) calculado el coeficiente de almacenamiento elástico para cada pozo, ii) realizado predicciones de la deformación del terreno y el nivel piezométrico en cada pozo durante el periodo de estudio, iii) elaborado mapas piezométricos para cada fecha de las imágenes radar, iv) estimado variaciones en el volumen de agua almacenada en el acuífero durante los diferentes ciclos de extracción/recuperación., The Tertiary detritic aquifer of Madrid (TDAM) supplies water to Madrid, the most populated city of Spain (3.2 million inhabitants in the metropolitan area). From 1992 to 2011 the aquifer experienced five cycles of groundwater extraction and recovery associated to two drought periods. In this study we analyse ground deformation associated to groundwater level changes. For this purpose, InSAR and piezometric time series spanning the period 1997-2011 have been analysed. The high correlation between both parameters (>85%) suggests that the relationship between ground deformation and groundwater level through time can be modelled using simple elastic models. Using these models: i) we the elastic storage coefficient for every well was estimated, ii) predictions of ground deformation and groundwater level evolution at each well were performed iii) piezometric maps for each SAR date were created, iv) groundwater storage variations during the different extraction/recovery cycle were estimated.

La Vega Media del Segura (VMS) se localiza en el sector este de la Cordillera Bética. El valle está relleno por sedimentos recientes (Holoceno-Plioceno) potencialmente deformables que han sido depositados por la acción de los ríos Segura y Guadalentín. La extracción de agua subterránea de los niveles permeables que constituyen el acuífero conlleva la consolidación de los materiales deformables, dando lugar a asientos de la superficie del terreno. La Interferometría SAR diferencial (InSAR) es una técnica remota que permite monitorizar de forma efectiva y precisa amplias extensiones del territorio. En este trabajo se describe las diferentes experiencias llevadas a cabo por los autores en la VMS, que han permitido avanzar en el entendimiento del funcionamiento hidrogeológico del acuífero para la comprensión del comportamiento geomecánico del subsuelo, así como para monitorizar los desplazamientos del terreno desde el año 1994 usando imágenes ERS, ENVISAT y TerraSAR-X, contribuyendo de forma efectiva al estudio, caracterización y modelización del fenómeno. Por último, se describen las tareas futuras a desarrollar haciendo uso de nuevos sensores SAR con el fin de asegurar la continuidad de la información disponible para el estudio de este fenómeno a lo largo del tiempo., The Vega Media of the Segura (VMS) is located in the eastern sector of the Betic Cordillera. The valley is filled of recent sediments (Holocene-Pliocene) potentially deformable, which have been deposited by the action of the Segura and Guadalentín rivers. Groundwater extraction from the existing permeable units that constitute the aquifer involves the consolidation of the deformable layers of soil, generating settlements on ground surface. Differential SAR Interferometry (InSAR) is a remote sensing technique which allows monitoring in an effective and precise way wide areas of the territory. In this work the different experiences developed by the authors in the VMS, which have allowed advancing in the understanding of the hydrogeological performance of the aquifer for the comprehension of the geomechanical behaviour of the ground, as well as to monitoring land subsidence from 1994 using ERS, ENVISAT and TerraSAR-X imagery contributing in an effective way to the study, characterization and modelling of the phenomenon, are described. Finally, the future tasks to be developed using new SAR sensors to ensure the continuity of the available information for the study of this phenomenon along time are depicted.

Tras el terremoto de Haití de 2010 dio comienzo una iniciativa para tratar de entender mejor los efectos de los terremotos en la República Dominicana, en particular en la ciudad de Santiago de los Caballeros, segunda más importante del país. Santiago ha sufrido varios terremotos devastadores, en 1562 la ciudad fue reconstruida en un nuevo sitio al sur de la falla responsable. El daño debido a un terremoto ocurre asociado a un conjunto de factores, entre ellos, la aceleración del suelo, que por lo general se señala como el principal o como la clave para explicar la mayor parte de los efectos. La aceleración del suelo varía dependiendo principalmente de la distancia al epicentro, de las propiedades del suelo y de la topografía. En cuanto a la distancia, es de esperar menor aceleración conforme aumenta la distancia al epicentro. De otra parte, suelos con diferentes características dan lugar a diferentes respuestas. Los efectos de la topografía aún no se comprenden bien. El efecto de la atenuación de la distancia en un radio de unos pocos kilómetros suele ser mucho menos relevante que el efecto de la variación en las propiedades de los suelos. Este artículo recoge los resultados obtenidos de los estudios de peligro sísmico y microzonificación sísmica en la ciudad de Santiago de los Caballeros: i) cuantificación del peligro sísmico regional debido a la falla septentrional; ii) un nuevo mapa geológico y iii) la cartografía de zonas de respuesta sísmica homogénea y susceptibilidad a la licuefacción

In the current context of climate change, improving groundwater monitoring and management is an important issue for human communities in arid environments. The exploitation of groundwater resources can trigger land subsidence producing damage in urban structures and infrastructures. Alto Guadalentín aquifer system in SE Spain has been exploited since 1960 producing an average piezometric level drop of 150 m. This work presents a groundwater model that reproduces groundwater evolution during 52 years with an average error below 10%. The geometry of the model was improved introducing a layer of less permeable and deformable soft soils derived from InSAR deformation and borehole data. The resulting aquifer system history of the piezometric level has been compared with ENVISAT deformation data to calculate a first-order relationship between groundwater changes, soft soil thickness, and surface deformation. This relationship has been validated with the displacement data from ERS and Cosmo-SkyMed satellites. The resulting regression function is then used as an empirical subsidence model to estimate a first approximation of the deformation of the aquifer system since the beginning of the groundwater extraction, reaching 1 to 5.5 m in 52 years. These rough estimations highlight the limitations of the proposed empirical model, requiring the implementation of a coupled hydrogeomechanical model.

Groundwater resources are under stress in many regions of the world and the future water supply for many populations, particularly in the driest places on Earth, is threatened. Future climatic conditions and population growth are expected to intensify the problem. Understanding the factors that control groundwater storage variation is crucial to mitigate its adverse consequences. In this work, we apply satellite-based measurements of ground deformation over the Tertiary detritic aquifer of Madrid (TDAM), Central Spain, to infer the spatio-temporal evolution of water levels and estimate groundwater storage variations. Specifically, we use Persistent Scatterer Interferometry (PSI) data during the period 1992–2010 and piezometric time series on 19 well sites covering the period 1997–2010 to build groundwater level maps and quantify groundwater storage variations. Our results reveal that groundwater storage loss occurred in two different periods, 1992–1999 and 2005–2010 and was mainly concentrated in a region of ∼200 km2. The presence of more compressible materials in that region combined with a long continuous water extraction can explain this volumetric deficit. This study illustrates how the combination of PSI and piezometric data can be used to detect small aquifers affected by groundwater storage loss helping to improve their sustainable management.

El acuífero terciario detrítico de Madrid (ATDM) proporciona agua a Madrid, la ciudad más poblada de España (3,2 millones de habitantes en el área metropolitana). Entre 1991 y 2011 el acuífero experimentó cinco ciclos de extracción y recuperación de agua subterránea, asociados a dos periodos de sequía. En este estudio hemos analizado la deformación del terreno producida por la extracción de agua subterránea y su posterior recuperación. Para ello se han analizado datos de interferometría radar (InSAR) y datos piezométricos en 19 pozos de extracción durante el periodo 1997-2010. La correlación entre la deformación del terreno y la piezometría en los pozos analizados es superior al 85% y, por lo tanto, es posible modelizar esta relación asumiendo un comportamiento elástico del acuífero. A partir de los modelos elásticos hemos: i) calculado el coeficiente de almacenamiento elástico para cada pozo, ii) realizado predicciones de la deformación del terreno y el nivel piezométrico en cada pozo durante el periodo de estudio, iii) elaborado mapas piezométricos para cada fecha de las imágenes radar, iv) estimado variaciones en el volumen de agua almacenada en el acuífero durante los diferentes ciclos de extracción/recuperación.

Tras el terremoto de Haití de 2010 dio comienzo una iniciativa para tratar de entender mejor los efectos de los terremotos en la República Dominicana, en particular en la ciudad de Santiago de los Caballeros, segunda más importante del país. Santiago ha sufrido varios terremotos devastadores, en 1562 la ciudad fue reconstruida en un nuevo sitio al sur de la falla responsable. El daño debido a un terremoto ocurre asociado a un conjunto de factores, entre ellos, la aceleración del suelo, que por lo general se señala como el principal o como la clave para explicar la mayor parte de los efectos. La aceleración del suelo varía dependiendo principalmente de la distancia al epicentro, de las propiedades del suelo y de la topografía. En cuanto a la distancia, es de esperar menor aceleración conforme aumenta la distancia al epicentro. De otra parte, suelos con diferentes características dan lugar a diferentes respuestas. Los efectos de la topografía aún no se comprenden bien. El efecto de la atenuación de la distancia en un radio de unos pocos kilómetros suele ser mucho menos relevante que el efecto de la variación en las propiedades de los suelos. Este artículo recoge los resultados obtenidos de los estudios de peligro sísmico y microzonificación sísmica en la ciudad de Santiago de los Caballeros: i) cuantificación del peligro sísmico regional debido a la falla septentrional; ii) un nuevo mapa geológico y iii) la cartografía de zonas de respuesta sísmica homogénea y susceptibilidad a la licuefacción

This paper presents an advanced 3D numerical methodology to reproduce the kinematics of slow active landslides, more precisely, to reproduce the nearly constant strain rate (secondary creep) and the acceleration/deceleration of the moving mass due to hydrological changes. For this purpose, finite element analyses are performed in a large area covering a long time-span (12 years), in order to exhibit different interacting slope movements. First, we perform a stability analysis using the shear strength reduction (SSR) technique with a Mohr-Coulomb failure criteria. It is done in order to compute factors of safety (FS) and to identify two different scenarios, the first one being stable (FS > 1) and the second one being unstable (FS < 1). In the studied test case, the Portalet landslide (Central Spanish Pyrenees), the first scenario corresponds to an initial stable configuration of the slope and the second one to an unstable excavated configuration. Second, taking the first scenario as an initial condition, a time-dependent analysis is performed using a coupled formulation to model solid skeleton and pore fluids interaction, and a simplified ground water model that takes into account daily rainfall intensity. In this case, a viscoplastic constitutive model based on Perzyna’s theory is applied to reproduce soil viscous behavior and the delayed creep deformation due to the excavation. The fluidity parameter is calibrated to reproduce displacements measured by the monitoring systems. Our results demonstrate that 3D analyses are preferable to 2D ones for reproducing in a more realistic way the slide behavior. After calibration, the proposed model is able to simulate successfully short- and medium-term predictions during stages of primary and secondary creep.

In the current context of climate change, improving groundwater monitoring and management is an important issue for human communities in arid environments. The exploitation of groundwater resources can trigger land subsidence producing damage in urban structures and infrastructures. Alto Guadalentín aquifer system in SE Spain has been exploited since 1960 producing an average piezometric level drop of 150 m. This work presents a groundwater model that reproduces groundwater evolution during 52 years with an average error below 10%. The geometry of the model was improved introducing a layer of less permeable and deformable soft soils derived from InSAR deformation and borehole data. The resulting aquifer system history of the piezometric level has been compared with ENVISAT deformation data to calculate a first-order relationship between groundwater changes, soft soil thickness, and surface deformation. This relationship has been validated with the displacement data from ERS and Cosmo-SkyMed satellites. The resulting regression function is then used as an empirical subsidence model to estimate a first approximation of the deformation of the aquifer system since the beginning of the groundwater extraction, reaching 1 to 5.5 m in 52 years. These rough estimations highlight the limitations of the proposed empirical model, requiring the implementation of a coupled hydrogeomechanical model.

This work integrates detailed geological and hydrogeological information with PSI data to obtain a better understanding of subsidence processes detected in the detrital aquifer of the Vega de Granada (SE Spain) during the past 13 years. Ground motion was monitored by exploiting SAR images from the ENVISAT (2003–2009), Cosmo-SkyMed (2011–2014) and Sentinel-1A (2015–2016) satellites. PSInSAR results show an inelastic deformation in the aquifer and small land surface displacements (up to −55 mm). The most widespread land subsidence is detected during the ENVISAT period (2003–2009), which coincided with a long, dry period in the region. The highest displacement rates recorded during this period (up to 10 mm/yr) were detected in the central part of the aquifer, where many villages are located. For this period, there is a good correlation between groundwater level depletion and the augmentation of the average subsidence velocity and slight hydraulic head changes (<2 m) have a rapid ground motion response. The Cosmo-SkyMed period (2011–2014) coincided with a rainy period, and the land subsidence is only concentrated in some points. Rates of average subsidence up to 11.5 mm/yr are obtained for this period and are anthropogenic in origin, being related to earthmoving works. During the Sentinel-1A monitoring period (2015–2016) most of the region showed no deformation, except for some points of unknown origin in the NE sector. A general conclusion is that there is a clear lithological control in the spatial distribution of ground subsidence; all the subsiding areas detected are located where a higher clay content was identified. Although the SE sector of the aquifer had more intense groundwater exploitation, no land subsidence processes were detected, as coarse-grained sediments predominate in the substratum. This research will contribute to the drawing-up of a management plan for the sustainable use of this strategic aquifer, taking into account critical levels of groundwater

La cuenca Alta del Guadalentín presenta una de las mayores tasas de subsidencia de Europa (>10 cm/año). Desde los años 60 el acuífero subyacente que alimenta parte de la agricultura del área de Lorca ha experimentado descensos piezométricos muy acusados, siendo declarado como sobreexplotado en 1987. La relación entre ambos fenómenos es uno de los principales objetivos del proyecto AQUARISK (Estudio de riesgos geológico geotécnicos por explotación de acuíferos mediante técnicas espaciales y terrestres. Aplicaciones a estructuras e infraestructuras urbanas. ESP2013-47780-C2-2-R).Como parte de este proyecto se están utilizando los resultados de deformación superficial obtenidos mediante interferometría radar (DInSAR) junto con datos geológicos e hidrogeológicos. Para complementar y validar los resultados se ha llevado a cabo una campaña de nivelación en 2016 y la instalación de una estación GPS permanente. A partir de los primeros resultados se están desarrollando nuevos productos que interrelacionan las componentes superficial y subterránea: a) subdivisión de las formaciones del acuífero por características deformacionales y productos SAR, b) construcción de un modelo numérico de flujo para el acuífero entre 1960 y 2012 que usa el anterior producto, c) generación de modelos geomecánicos que reproduzcan las deformaciones que se presentan en la zona a partir de los cambios en el acuífero.

We model debris flows using two sets of nodes, describing the water and the solid phases, which can move relative to each other. We present first the mathematical model which will be used, deriving it from Zienkiewicz-Shiomi model, and arriving to the depth integrated model proposed by Pitman and Le. Then, we present the rheological models describing solid, fluid and their interaction. Next, the SPH model for two phases will be described. Finally, we present some application cases where we will compare the results provided by the proposed model against those obtained using more simplified models.

La Vega Media del Segura (VMS) se localiza en el sector este de la Cordillera Bética. El valle está relleno por sedimentos recientes (Holoceno-Plioceno) potencialmente deformables que han sido depositados por la acción de los ríos Segura y Guadalentín. La extracción de agua subterránea de los niveles permeables que constituyen el acuífero conlleva la consolidación de los materiales deformables, dando lugar a asientos de la superficie del terreno. La Interferometría SAR diferencial (InSAR) es una técnica remota que permite monitorizar de forma efectiva y precisa amplias extensiones del territorio. En este trabajo se describe las diferentes experiencias llevadas a cabo por los autores en la VMS, que han permitido avanzar en el entendimiento del funcionamiento hidrogeológico del acuífero para la comprensión del comportamiento geomecánico del subsuelo, así como para monitorizar los desplazamientos del terreno desde el año 1994 usando imágenes ERS, ENVISAT y TerraSAR-X, contribuyendo de forma efectiva al estudio, caracterización y modelización del fenómeno. Por último, se describen las tareas futuras a desarrollar haciendo uso de nuevos sensores SAR con el fin de asegurar la continuidad de la información disponible para el estudio de este fenómeno a lo largo del tiempo.

Monitoring is essential to understand the mechanics of landslides, and predict their behavior in time and space. In this work we discuss the performance of multi-sensor monitoring techniques applied to measure the kinematics and the landslide hydrology of Portalet landslide complex, which is located in the SW-facing slopes of Petrasos peak at the border between Spain and France. In the summer 2004, the excavation of a parking lot at the foot of the slides triggered a secondary failure in the lower part of the slope, accelerating the dynamic of the landslide complex. The deployed hydro-meteorological network has been useful to understand that the greatest infiltration in the moving mass is produced in spring due to the combination of snow melt and seasonal rainfall. Landslide surface kinematics measured with differential GPS (D-GPS) were useful to measure the slower (<10 cm/year) and faster (20–30 cm/year) dynamic of the landslide complex. Advanced DInSAR was useful to monitor the slower ground displacements from long datasets of SAR images, providing a wider spatial coverage and measurement point density than the D-GPS. In addition, the NL-InSAR processing strategy was applied to monitor the faster motion using short datasets of TerraSAR-X images excluding the snow cover period. The installed horizontal extensometers were useful to study the extension of the head scarp and its relationship with landslide hydrology, which is affected by the retrogressive effect of the landslide due to the loss of lateral confining pressure. Finally, an inclinometric robot system (AIS) was the only technique capable of detecting 5–6 time faster motion after the snow melt, since it provides daily measurements with high accuracy even during the snow cover period. These data, even if expensive to gather, are necessary to improve the hydro-mechanical modeling of large slow landslides, such as those already proposed for Portalet landslide complex.

Subsidence due to groundwater overexploitation has been recognized in the metropolitan area of Murcia (25 km2) in south-eastern Spain since the early 1990s. Previous published works have focused their attention on land subsidence that occurred during the drought period between 1995 and 2008. This work first analyzes the groundwater recovery that has occurred since 2008 and then determines the kind of associated ground deformation detected by the new extensometric data. Subsequently, subsidence time series are computed on 24 geotechnical boreholes scattered throughout the study area by means of a hydro-mechanical finite element code and a linear-elastic constitutive law. A spatio-temporal interpolation of the numerically modeled surface displacements is performed over the whole domain and compared with extensometers and DInSAR-derived displacement maps in two different periods: the drought period from 2004 to 2008, and the recovery period from 2008 to 2012. In spite of the limited information on the geomechanical parameters characterizing the modelled geological formations, the proposed approach is able to discriminate areas where the soils have an elastic behavior (small differences in the comparisons) or an elasto-plastic behavior (large differences in the comparisons). This zonation enhances the understanding of the subsidence phenomenon in Murcia City and could prevent, from a quantitatively point of view, future severe subsidence due to aquifer overexploitation.

El acuífero terciario detrítico de Madrid (ATDM) refuerza el suministro de agua a parte de la Comunidad Autónoma de Madrid, incluyendo Madrid, la ciudad más poblada de España (3.2 millones de habitantes en el área metropolitana). Entre 1992 y 2011 el acuífero experimentó cinco ciclos de extracción asociados a varios periodos de sequía. En este trabajo se analiza la deformación del terreno producida por la extracción de agua y su posterior recuperación utilizando para ello la técnica de interferometría de radar (InSAR). Para ello se han analizado series temporales InSAR y datos piezométricos en 19 pozos de extracción durante el periodo 1997-2010. La correlación entre la deformación del terreno y la piezometría en los pozos analizados es superior al 85%, siendo pues posible modelizar esta relación asumiendo un comportamiento elástico del acuífero. Para construir los modelos elásticos, primero se estima el coeficiente de almacenamiento elástico (Ske) para cada pozo, que muestra un gradiente N-S correlacionado con un cambio litológico gradual en el acuífero. Este coeficiente es utilizado después para predecir la deformación del terreno y el nivel piezométrico en cada pozo durante el periodo de estudio. Por último, se discute la posibilidad de extender este análisis a todo el ATDM para crear mapas piezométricos y estimar variaciones en el volumen de agua almacenada en el acuífero.

Multi-sensor advanced DInSAR analyses have been performed and compared with two GPS station measurements, in order to evaluate the land subsidence evolution in a 20-year period, in the Alto Guadalentín Basin where the highest rate of man-induced subsidence (> 10 cm yr−1) of Europe had been detected. The control mechanisms have been examined comparing the advanced DInSAR data with conditioning and triggering factors (i.e. isobaths of Plio-Quaternary deposits, soft soil thickness and piezometric level).