Vertical ground movements in the Polish and Lithuanian Baltic coastal area as measured by satellite interferometry (original) (raw)
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The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2019
The project 'Determinations on the absolute sea-level rise on the German North Sea and Baltic Sea coasts', funded by the Federal Ministry of Education and Research (BMBF) , has the overall goal to estimate the absolute sea level change in those coastal areas. A major issue associated with detecting absolute sea level changes is the relative character of tidal records. To calibrate the tidal records, a spatial vertical land movement model for northern Germany has been set up. To this end we combined a network from German Height Reference Systems (Deutsches Haupthöhennetz, DHHN 95 and DHHN 2016), reprocessed data from 180 permanent GNSS stations and results from Persistent Scatterer (PS) Interferometry. PS processing covers an approximately 50 km wide strip along the 1200 km long German coast. We processed two tracks from Sentinel-1A and-1B from October 2014 to September 2018 and generated a combined spatial solution for the estimation of vertical land movement. In general, vertical velocities from PS Interferometry range between ±2 mm/a and show a homogeneous distribution for coastal areas. Therefore we consider them as stable. We observe subsidence in the area around Groningen and Emden through hydrocarbon extraction. In Wilhelmshaven and Etzel subsidence associated with cavern storage is visible. Processed GNSS data and PSI results overlap in time from 2014 to 2016. The integration of the spatial multi-temporal PS results with point-wise GNSS time series data are required, as they form the main input data for the further development of our vertical displacement model of northern Germany.
Geophysical Journal International, 2015
The intra-plate deformation of the Upper Rhine Graben (URG) located in Central Europe is investigated using geodetic measurement techniques. We present a new approach to calculate a combined velocity field from InSAR, levelling and GNSS measurements. As the expected tectonic movements in the URG area are small (less than 1 mm a −1), the best possible solutions for linear velocity rates from single-technique analyses are estimated in a first step. Second, we combine the velocity rates obtained from InSAR (line of sight velocity rates in ascending and descending image geometries), levelling (vertical velocity rates) and GNSS (horizontal velocity rates) using least-squares adjustment (LSA). Focusing on the Northern URG area, we analyse SAR data on four different image stacks (ERS ascending, ERS descending, Envisat ascending, Envisat descending) using the Persistent Scatterer (PS) approach. The linear velocity rates in ascending and descending image geometries, respectively, are estimated in an LSA from joint time-series analysis of ERS and Envisat data. Vertical velocity rates from levelling are obtained from a consistent adjustment of more than 40 000 measured height differences using a kinematic displacement model. Horizontal velocity rates in east and north direction are calculated from a time-series analysis of daily coordinate estimates at 76 permanently operating GNSS sites in the URG region. As the locations, at which the measurement data of PS-InSAR, levelling and GNSS reside, do not coincide, spatial interpolation is needed during several steps of the rigorous processing. We use Ordinary Kriging to interpolate from a given set of data points to the locations of interest with a special focus on the modeling and propagation of errors. The final 3-D velocity field is calculated at a 200 m grid, which carries values only close to the location of PS points, resulting in a mean horizontal and vertical precision of 0.30 and 0.13 mm a −1 , respectively. The vertical component of the combined velocity field shows a significant subsidence of about 0.5 mm a −1 in the northern part of the graben coinciding with a well-known quaternary basin structure. Horizontal displacement rates of up to 0.8 mm a −1 in southeast direction are observed outside the graben, in reasonable alignment with the average direction of maximum horizontal stress. Within the graben, the velocity directions rotate toward east in the non-subsiding part, while an opposite trend is observed in the subsiding part of the graben. The complexities of the observed velocity field are compatible to the geomechanical situation in our investigation area which is characterized by a transition from a restraining to a releasing bend setting. Glacial isostatic adjustment is another potential source influencing the observed velocity field, as well as anthropogenic signals due to mining, oil exploration and groundwater usage that have been identified in some places.
Landslides and Subsidence Assessment in the Crati Valley (Southern Italy) Using InSAR Data
Geosciences
In this work, we map surficial ground deformations that occurred during the years 2004-2010 in the Crati Valley (Southern Italy). The valley is in one of the most seismically active regions of the Italian peninsula, and presents slope instability and widespread landslide phenomena. We measured ground deformations by applying the small baseline subset (SBAS) technique, a multi-temporal synthetic aperture radar interferometry (InSAR) methodology that is used to process datasets of synthetic aperture radar (SAR) images. Ground displacements are only partially visible with the InSAR technique. Visibility depends on the geometry of the acquisition layout, such as the radar acquisition angle view, and the land use. These two factors determine the backscattering of the reflected signal. Most of the ground deformation detected by InSAR can be attributed to the gravitational mass movements of the hillslopes (i.e., landslides), and the subsidence of the quaternary deposits filling the valley. The movements observed along the valley slopes were compared with the available landslide catalog. We also identified another cause of movement in this area, i.e., ground subsidence due to the compaction of the quaternary deposits filling the valley. This compaction can be ascribed to various sources, such as urban population growth and sprawl, industrial water withdrawal, and tectonic activity.
Engineering Geology for Society and Territory - Volume 5, 2014
This paper focuses on a multidisciplinary study carried out in an urban area affected by subsidence. The area is located about 20 km east of Rome (Italy) and is affected by dewatering processes mainly linked to quarry activities. Furthermore, compressible soils are locally present immediately below the ground level. Persistent Scatterer Interferometric Synthetic Aperture Radar (InSAR) analyses carried out with different approaches on ERS and ENVISAT data were performed. The so reconstructed time series of ground displacements were then coupled and compared with a detailed geological model and the variations over time of piezometric levels. Such data overlay allowed us to better understand and constrain the relation among ground displacement, piezometric variations, geological setting and geotechnical properties of subsoil.
Sustainability
In this work, we use X and C-band SAR data provided by the COSMO-SkyMed and ENVISAT missions to detect and measure some ground deformation phenomena along six coastal areas of Italy. In particular, we exploit multi-temporal interferometric synthetic aperture radar (InSAR), i.e., small baseline subsets (SBAS) and interferometric point target analysis (IPTA) methods, to retrieve the deformation rate maps and time series for each investigated area. Multi-temporal InSAR analysis revealed local subsidence and uplifting effects in Ravenna Coastal Areas, Fiumicino, Campi Flegrei, Sibari Plain, Augusta Bay, and Taranto Gulf. Our work is meant as a demonstrator to show how InSAR-based analysis can provide a detailed understanding of the coastal hazards. Such analysis also opens up new monitoring scenarios such as the possibility of designing a near real-time surveillance service based on Sentinel-1 SAR data.
Land subsidence in the broader Kalochori village region, at the west side of Thessaloniki, has been recorded since the early 1960s reaching gradually, next to the coastline, maximum values of 3–4 m. Temporal monitoring of terrain movements are exploited and combined with in-situ data to enhance understanding of the deformation signals. Persistent Scatterer Interferometry (PSI) and Small Baseline Subset (SBAS) multi-temporal Interferometric approach are applied for the analysis of a 20 year ERS 1, 2 and ENVISAT dataset. The velocities estimated for the ERS dataset are in excellent accordance with previous studies, depicting subsidence with magnitude up to 35 mm/year. The intriguing output of the ENVISAT data archive (2003–2010) shows that, during the second decade , there was a change in motion trend, from subsidence to uplift. The fact that this uplifting trend of the second decade is well correlated with hydrogeological data of the area that show a synchronous rise of the aquifer level, verifies the dominating driver of the human factor concerning the land subsidence phenomena taking place the last 55 years. This conclusion is further supported by the fact that since 2007 the uplifting signal becomes smoother, following the smoother recovery of the aquifers.
This study deals with the estimation of subtle ground deformation at millimetric accuracy over the broader area of the Mornos River delta in Central Greece and its spatio-temporal distribution for the period between 1992 and 2009 through Persistent Scatterers Interferometry (PSI). The results showed that the majority of the scatterers, which show subsidence, are located within the delta plain with mean subsidence rates throughout the delta varying between 27.2 and +0.7 mm/y. An attempt is made to highlight the geographic distribution, the amplitude, and the causes of the observed delta plain subsidence. The positive correlation between the thickness of the fine-grained Holocene deltaic deposits and the subsidence rates reveals that the main cause is the natural compaction of sediments. The highest subsidence is observed at Bouka Karahassani village, which corresponds to the area of the most recently abandoned river mouth, which is intensely eroded by marine processes. Apart from the dominance of fine sediments in the study area, subsidence may also be attributed to submarine gravitational mass movements along the steep slopes of the prodelta as well as to the reduction of sediment load after the dam construction in 1979. The NW part of the delta seems to have been affected by aseismic slip along a NE-SW trending normal fault buried beneath the alluvial deposits of the Skala torrent fan.
PS InSAR Integrated with Geotechnical GIS: Some Examples from Southern Lombardia
International Association of Geodesy Symposia
The Oltrepo Pavese, which extends for almost 1100 km 2 in Lombardia Region (Northern Italy), has a complex geological-structural setting resulting from overthrusting of different tectonic units made up mainly of clays. All these characteristics make the Oltrepo Pavese particularly vulnerable to hydrogeological risk: shallow and deep landslides in the hill, swelling/shrinkage of the clayey soils and subsidence in the plain. In order to understand more about the hydrogeological hazard (related to landslides and other phenomena) and related risk in the Oltrepo Pavese area the Regione Lombardia decided to test the use of the Permanent Scatterers Technique. The Permanent Scatterers (PS) Technique is an advanced technique for the processing of SAR data developed by Politecnico of Milano. The PS Technique overcomes the main limits of conventional approaches to surface deformation detection due to temporal and geometric decorrelation. The PS data sets and their temporal series were included on a geological and geotechnical GIS supported database , where they were integrated with geological-structural, hydrogeological and geomorphologic data. Spatial and temporal clusters were highlighted and/or discovered. They are generally related to ground deformation due to well known phenomena (swelling/shrinkage, landslides, overpumping) or to unknown phenomena (uplift).