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

Comparación del tec obtenido a partir de la rotación Faraday de las señales de satélites geoestacionario y de los datos GPS

En: Sardón, E., Rius, A., Zarraoa, N. GPS inospheric delays. Publicación. Instituto de Astronomía y Geodesia, nº 185, 1993.In this paper we compare the ionospheric total electron content (TEC) obtained from Faraday rotation observations carried out at Neustrelitz (Germany), and the total electron content predicted for the same subionospheric points using Global Positioning System data gathered at Wettzell (Germany). Three different periods with data have been compared. In general, the same features for the TEC are reproduced by both results. For two of the compared periods there is a bias between both results, possibly due to the unknown initial polarization, the unresolved ambiguities in the Faraday-derived TEC or to plasmaspheric contributions. Another source of discrepancies between both results are deficiencies in the way of predicting the TEC at Neustrelitz using data from Wettzell.Peer reviewe

La falla activa de Padul. Medidas geodésicas para controlar su deformación

3 páginas.O Nigüelas. La mayor sismicidad de la Península se da en el sector central de la cordillera Bética, con terremotos de baja intensidad. Se estableció una red geodésica en el Barranco de los Lobos, con 8 vértices geodésicos de hormigón.Peer reviewe

PS-InSAR processing methodologies in the detection of field surface deformation—Study of the Granada basin (Central Betic Cordilleras, southern Spain)

9 páginas, 8 figuras, 1 tabla.Differential SAR interferometry (DInSAR) is a very effective technique for measuring crustal deformation. However, almost all interferograms include large areas where the signals decorrelate and no measurements are possible. Persistent scatterer interferometry (PS-InSAR) overcomes the decorrelation problem by identifying resolution elements whose echo is dominated by a single scatterer in a series of interferograms. Two time series of 29 ERS-1/2 and 22 ENVISAT ASAR acquisitions of the Granada basin, located in the central sector of the Betic Cordillera (southern Spain), covering the period from 1992 to 2005, were analyzed. Rough topography of the study area associated to its moderate activity geodynamic setting, including faults and folds in an uplifting relief by the oblique Eurasian–African plate convergence, poses a challenge for the application of interferometric techniques. The expected tectonic deformation rates are in the order of 1 mm/yr, which are at the feasibility limit of current InSAR techniques. In order to evaluate whether, under these conditions, InSAR techniques can still be used to monitor deformations we have applied and compared two PS-InSAR approaches: DePSI, the PS-InSAR package developed at Delft University of Technology (TU Delft) and StaMPS (Stanford Method for Persistent Scatterers) developed at Stanford University. Ground motion processes have been identified for the first time in the study area, the most significant process being a subsidence bowl located at the village of Otura. The idea behind this comparative study is to analyze which of the two PS-InSAR approaches considered might be more appropriate for the study of specific areas/environments and to attempt to evaluate the potentialities and benefits that could be derived for the integration of those methodologies.This research was supported by the European Space Agency (ESA) in the scope of 3858 and 3963 CAT-1 projects, the PR2006-0330, ESP2006-28463-E, CSD2006- 00041, and CGL 2006-06001 projects from Ministerio de Educación y Ciencia (Spain), the RNM-149 and RNM-282 research groups of the Junta de Andalucía (Spain) and Fundação para a Ciência e a Tecnologia (Portugal). TUDelft radar group and Stanford University are gratefully acknowledged for all the technical support. The SRTM data were provided by USGS/NASA.Peer reviewe

Establishment of a non-permanent GPS network to monitor deformations in Zafarraya Fault and Sierra Tejeda Antiform (Spain)

The NW-SE to NNW-SSE convergence between the African and Eurasian plates in the western Mediterranean has developed the recent relief of the Betic-Rif Cordilleras. The central part of the Internal Zones of the Betic Cordilleras is deformed by large open folds and faults, mainly with normal character. The Zafarraya fault, located to the N of the Sierra Tejeda antiform, was active during the 1884 Andalusia earthquake of 6.7 estimated magnitude. In the framework of an interdisciplinary research project, a non-permanent GPS-network has been established at Zafarraya Fault and Sierra Tejeda antiform to monitor deformations related to these active tectonic structures.Peer reviewe

Mise en evidence par mesures GPS d`une tectonique active compressive dans les provinces nord du Maroc

Workshop Alboran domain and Gibraltar Arc: geological research and natural hazards, Granada (Spain), 16th-18th october, 201

An inventory of Land Subsidence along the southern coast of Spain detected by satellite radar interferometry

International Workshop on “Advances in the Science and Applications of SAR Interferometry and Sentinel-1 InSAR (10º. 2017. Helsinki)Multi-temporal InSAR methods are effective tools for monitoring and investigating surface displacement on Earth based on conventional radar interferometry. These techniques allow us to measure deformation with uncertainties of one millimeter per year, interpreting time series of interferometric phases at coherent point scatterers (PS). Over the last decades, coastal areas in many parts of Spain have undergone a continuous urban expansion because of the growth of cities and development of new residential areas. The transgression of the sea, as a consequence of sea level rise and the subsidence of populated areas, may result in serious problems to many constructions situated in the coastline. This has an important impact on the economy, environment and society, representing a considerable natural hazard. We use ERS-1/2 and Envisat data in the period 1992-2010 to detect subsidence areas over the southern Spanish coast using time series analysis of SAR data.Departamento de Ingeniería Cartográfica, Geodésica y Fotogrametría, Universidad de Jaén, EspañaCentro de Estudios Avanzados en Ciencias de la Tierra, Universidad de Jaén, EspañaGrupo de investigación Microgeodesia Jaén, Universidad de Jaén, EspañaInstituto Geológico y Minero de España, EspañaPeer reviewe

GPS tectonic displacements on a main active sinistral blind fault tip: a key to integrate seismic and geological evidences in a collisional setting (Al Hoceima area, Rif belt, western Mediterranean)

European Geosciences Union (EGU) General Assembly, 7-12 April 2019, Vienna, Austria.-- 1 pageThe NW-SE Eurasian-African plate convergence formed the Rif and Betic Cordilleras around the Alboran Sea in the westernmost Mediterranean. Seismicity in this region is notably concentrated along a NE-SW band crossing from the Campo de Dalías, in Betics (Spain), to the Al Hoceima region in the Rif (Morocco), an area affected by the 1994, 2004 and 2016 onshore and offshore seismic series. This deformation zone has been proposed to be a main segment of the plate boundary and corresponds to the northwestern limit of a rigid basement spur of the African plate in a setting of indentation tectonics. The onshore Al Hoceima region was affected by the catastrophic earthquake of January 24, 2004 (M= 6.4, depth 7 to 10 km) and the related seismic series is characterized by strike-slip focal mechanisms supporting the presence of NNE-SSW sinistral or WNW-ESE dextral faults. However, there is not any evidence of surface strike-slip faults in the epicentral area, which instead was affected by minor NE-SW extensional structures evidenced by fractures in Quaternary pebbles, minor conjugate normal faults, and vertical open joints. Geological researches evidence that main normal and transtensional faults are located eastward of the epicentral area, onshore and offshore of the Nekor bay, and westward in the Bokoya Massif. A non-permanent GPS network consisting of 6 sites has been installed since June 2007, and we have obtained yearly measurements. They provide an accurate result of the present-day deformation field that is helping to solve the apparent disagreement between seismological and geological observations. The three sites located east of the 2004 series epicentral area have motions roughly consistent with the Nubia (African) plate and evidence the very low activity of the prominent Plio-Quaternary Nekor basin faults. Contrasting, the three sites located on the epicentral and western region undergone a very fast motion (between 2 and 3 mm/yr) towards the WSW with respect to stable Nubia. This result supports an ENE-WSW surface extension and is in agreement with the subtle very recent geological deformation and the extensional stress of the earthquake focal mechanisms. The analysis of the 2016 seismic series that occurred in Alboran Sea provide similar results, suggesting a recent westward migration of the deformation. The integration of all these results support that the main sinistral fault zone crossing the Alboran Sea propagates up to the Al Hoceima region basement, while the shallow tectonic units are detached and their deformation and displacement are mainly determined by the orientation of the ENE-WSW extensional stresses. This is a complex setting for paleoseismological studies and seismic hazard assessment because the main recent outcropping faults have become inactive and the new main active structures are blind strike-slip faults. The integration of geodetic data have been proven essential to integrate the apparently disharmonious seismic and geological dat

The Al Hoceima seismic zone (SW prolongation of the EBSZ in the Rif): GPS evidences of deep tectonic displacements on a main active blind sinistral fault

4th Fault2SHA Workshop, Fault Complex Interaction: Characterization and Integration into Seismic Hazard Assessment (SHA), 3-5 June 2019, BarcelonaThe Al Hoceima seismic zone is located at the southwestward prolongation of the Eastern Betic Shear Zone that crosses the Alboran Sea and reaches up to the Rif. This region was affected by the 1994, 2004 and 2016 onshore and offshore seismic crisis and constitutes one of the most active areas of the westernmost Mediterranean. The January 24, 2004 (M= 6.4, depth 7 to 10 km) earthquake was related to a NNE-SSW sinistral or a WNW-ESE dextral vertical fault, but in spite of its shallow origin, no tectonic field ruptures were recognized. Anyway, the epicentral region evidences NE-SW to E-W brittle extensional structures: Quaternary fractured pebbles, conjugate normal faults and open joints. The main normal and transtensional faults in the region are located eastwards of the zone affected by seismicity, onshore and offshore of the Nekor bay. A non-permanent GPS network composed by 6 sites and measured since June 2007 evidence very moderate or absent activity of the main outcropping faults surrounding the Nekor Basin. However, very high rates (up to 2- 3mm /yr) of ENE-WSW extension have been detected in the epicentral zone. These field data are in agreement with those obtained on the analysis of the 2016 seismic series in the Alboran Sea, that evidence a westward migration of the deformation in the region. While the main sinistral EBSZ propagates southwestward up to the Rif affecting the basement, shallow tectonics units probably are detached and only being affected by the extensional deformation above the deeper main crustal fault. This complex setting may constitute a key area to advance in paleoseismological and seismic hazard assessment studies because the main recent outcropping faults have become inactive and the new main active structures are blind strike-slip faultsPeer Reviewe