Mexico City land subsidence in 2014-2015 with Sentinel-1 IW TOPS: results using the Intermittent SBAS (ISBAS) technique

Differential Interferometric Synthetic Aperture Radar (DInSAR) can be considered as an efficient and cost effective technique for monitoring land subsidence due to its large spatial coverage and high accuracy provided. The recent commissioning of the first Sentinel-1 satellite offers improved support to operational surveys using DInSAR due to regular observations from a wide-area product. In this paper we show the results of an intermittent small-baseline subset (ISBAS) time-series analysis of 18 Interferometric Wide swath (IW) products of a 39,000 km2 area of Mexico acquired between 3 October 2014 and 7 May 2015 using the Terrain Observation with Progressive Scans in azimuth (TOPS) imaging mode. The ISBAS processing was based upon the analysis of 143 small-baseline differential interferograms. After the debursting, merging and deramping steps necessary to process Sentinel-1 IW roducts, the method followed a standard approach to the DInSAR analysis. The Sentinel-1 ISBAS results confirm the magnitude and extent of the deformation that was observed in Mexico City, Chalco, Ciudad Nezahualcóyotl and Iztapalapa by other C-band and L-band DInSAR studies during the 1990s and 2000s. Subsidence velocities from the Sentinel-1 analysis are, in places, in excess of -24 cm/year along the satellite line-of-sight, equivalent to over ~-40 cm/year vertical rates. This paper demonstrates the potential of Sentinel-1 IW TOPS imagery to support wide-area DInSAR surveys over what is a very large and diverse area in terms of land cover and topography

Fortgeschrittene InSAR Methodologie zum Studium vom Bodensenkung und Rissbildung aufgrund von Grundwasserentnahmen im Tal von Mexiko

Radar remote sensing techniques are well suited for deformation studies. The Mexico City subsidence,for example, has been mapped using both the conventional and multi-temporal methods; however, no complete characterization and detailed temporal analysis of the land settlement in the entire Valley of Mexico, covering the lakebed of the five ancient lakes (Chalco, Xochimilco, Texcoco, Xaltocan and Zumpango) has been performed until now. In this work, we mapped and analysed the subsidence and associated earth fissuring in the Valley by exploiting, for the first time, the Small Baseline method from StaMPS. The inversion methodology was studied in detail and interpreted, and the algorithm was adjusted to select a spatial reference on the basis of the surface geology information. This extended algorithm was assessed by comparing the results obtained with existing ones particularly over the southern Valley. Furthermore, unwrapping and quality of the times series were analysed using maps of system misclosure. Our results indicate that the proposed algorithm adapts adequately to the study area. Detailed ERS and ENVISAT conventional and multi-temporal InSAR analysis for the 1999-2000 and 2002-2010 periods, respectively, were performed on northern Valley of Mexico. Both urban and rural areas are experiencing subsidence, and rapid rates were found in densely populated areas or where sizeable volumes of water are used for crop irrigation. Time series were used to evaluate the impact of the subsidence on important infrastructure such as the Tunel Emisor Oriente. As second main aspect, the flexibility of the proposed InSAR algorithm to identify points undergoing non-linear deformation was exploited to develop a methodology that contributes to the location of soil fractures and to the understanding of their dynamics. Fissure-prone zones identified by this method, effectively coincided with existing records of ground failures. The fracture trigger mechanisms are furthermore discussed and evaluated where notable acceleration or deceleration is found. The proposed soil fracture identification approach provided useful and valuable information for improving the vulnerability maps in the area.Radarfernerkundungstechniken sind gut geeignet um Deformationsprozesse zu studieren. Beispielsweise wurden die Setzungen in Mexico City mit konventionellen und multitemporalen Methoden erfasst; allerdings wurde bis jetzt keine komplette Charakterisierung und detaillierte zeitliche Analyse der Landbesiedelung im gesamten Tal von Mexiko, die das Seebett von fünf ehemaligen Seen (Chalco, Xochimilco, Texcoco, Xaltocan und Zumpango) beinhaltet, durchgeführt. In dieser Arbeit wurde die Bodensenkungen und die dazugehörigen Boden-Brüche im Tal von Mexiko mit Hilfe der Small Baseline Methode von StaMPS kartiert und analysiert. Die dazugehörige Inversionsmethode wurde im Detail studiert und interpretiert und dieser Algorithmus auf Basis der geologischen Information so angepasst, dass die Ergebnisse als räumliche Referenz dienen können. Dieser erweiterte Algorithmus wurde durch den Vergleich mit existierenden Ergebnissen aus dem südlichen Tal validiert. Das „Unwrapping“ und die Qualität der Zeitreihen wurden mit statistischen Verfahren bewertet. Detaillierte Analysen von ERS- und ENVISAT-Daten mit konventionellem und multitemporalem InSAR für die Zeiträume von 1999-2000 und von 2002-2010 wurden im Norden des Talbereiches von Mexico durchgeführt. Sowohl die städtischen als auch die ländlichen Bereiche erfahren Bodensenkungen. Große Setzungsraten wurden besonders in dicht bevölkerten Gebieten gefunden oder in Bereichen mit beträchtlicher Wasserentnahme zur Feldbewässerung. Die Zeitreihen wurden verwendet um die Auswirkungen der GW-Entnahme auf wichtige Infrastrukturprojekte zu bewerten,z.B. den Tunel Emisor Oriente. Als weiterer Schwerpunkt wurde die Flexibilität des verwendeten InSAR Algorithmus genutzt, um nichtlineare Verformung zu identifizieren und eine Methode zur Lokalisierung von Boden-Bruchzonen zu entwickeln und um ihre Dynamik zu verstehen. Die Lage der mit dieser Methode identifizierten Bruchzonen stimmt mit existierenden Aufzeichnungen von Bruchaktivitäten überein. Die Bruchauslösemechanismen werden an den Stellen diskutiert und bewertet, an denen deutliche Beschleunigungen oder Verzögerungen erkannt wurden. Der vorgestellte Ansatz zur Identifikation der Brüche stellt nützliche und wertvolle Informationen für die Verbesserung der Schadenskarten in diesem Gebiet dar

Generic interferometric synthetic aperture radar atmospheric correction model and its application to co- and post-seismic motions

PhD ThesisThe tremendous development of Interferometric Synthetic Aperture Radar (InSAR) missions in recent years facilitates the study of smaller amplitude ground deformation over greater spatial scales using longer time series. However, this poses more challenges for correcting atmospheric effects due to the spatial-temporal variability of atmospheric delays. Previous attempts have used observations from Global Positioning System (GPS) and Numerical Weather Models (NWMs) to separate the atmospheric delays, but they are limited by (i) the availability (and distribution) of GPS stations; (ii) the time difference between NWM and radar observations; and (iii) the difficulties in quantifying their performance. To overcome the abovementioned limitations, we have developed the Iterative Tropospheric Decomposition (ITD) model to reduce the coupling effects of the troposphere turbulence and stratification and hence achieve similar performances over flat and mountainous terrains. Highresolution European Centre for Medium-Range Weather Forecasts (ECMWF) and GPS-derived tropospheric delays were properly integrated by investigating the GPS network geometry and topography variations. These led to a generic atmospheric correction model with a range of notable features: (i) global coverage, (ii) all-weather, all-time usability, (iii) available with a maximum of two-day latency, and (iv) indicators available to assess the model’s performance and feasibility. The generic atmospheric correction model enables the investigation of the small magnitude coseismic deformation of the 2017 Mw-6.4 Nyingchi earthquake from InSAR observations in spite of substantial atmospheric contamination. It can also minimize the temporal correlations of InSAR atmospheric delays so that reliable velocity maps over large spatial extents can be achieved. Its application to the post-seismic motion following the 2016 Kaikoura earthquake shows a success to recover the time-dependent afterslip distribution, which in turn evidences the deep inactive subduction slip mechanism. This procedure can be used to map surface deformation in other scenarios including volcanic eruptions, tectonic rifting, cracking, and city subsidence.This work was supported by a Chinese Scholarship Council studentship. Part of this work was also supported by the UK NERC through the Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonics (COMET)

Current status and long-term insights into the western Dead Sea groundwater system using multi-sensoral remote sensing

Arid regions, that have a terrestrial share of 30 %, heavily rely on groundwater for do-mestic, industrial and irrigation purposes. The reliance on groundwater has partly turned into a dependency in areas where the increasing population number and the expansion of irrigated agricultural areas demand more groundwater than is naturally replenished. Yet, spatial and temporal information on groundwater are often scarce induced by the facts that groundwater is given a low priority in many national budgets and numerous (semi-) arid regions in the world encompass large and inaccessible areas. Hence, there is an urgent need to provide low-cost alternatives that in parallel cover large spatial and temporal scales to gain information on the groundwater system. Remote sensing holds a tremendous potential to represent this alternative. The main objective of this thesis is the improvement of existing and the development of novel remote sensing applications to infer information on the scarce but indispensable resource groundwater at the example of the Dead Sea. The background of these de-velopments relies mainly on freely available satellite data sets. I investigate 1) the pos-sibility to infer potential groundwater flow-paths from digital elevation models, 2) the applicability of multi-temporal thermal satellite data to identify groundwater discharge locations, 3) the suitability of multi-temporal thermal satellite data to derive information on the long-term groundwater discharge behaviour, and 4) the differences of thermal data in terms of groundwater discharge between coarse-scaled satellite data and fine-scaled airborne data including a discharge quantification approach. 1) I develop a transparent, reproducible and objective semi-automatic approach us-ing a combined linear filtering and object based classification approach that bases on a medium resolution (30 m ground sampling distance) digital elevation model to extract lineaments. I demonstrate that the obtained lineaments have both, a hydrogeological and groundwater significance, that allow the derivation of potential groundwater flow-paths. These flow-paths match results of existing groundwater flow models remarkably well that validate the findings and shows the possibility to infer potential groundwater flow-paths from remote sensing data. 2) Thermal satellite data enable to identify groundwater discharge into open water bodies given a temperature contrast between groundwater and water body. Integrating a series of thermal data from different periods into a multi-temporal analysis accounts for the groundwater discharge intermittency and hence allows obtaining a representa-tive discharge picture. I analyse the constraints that arise with the multi-temporal anal-ysis (2000-2002) and show that ephemeral surface-runoff causes similar thermal anomalies as groundwater. To exclude surface-runoff influenced data I develop an au-tonomously operating method that facilitates the identification. I calculate on the re-maining surface-runoff uninfluenced data series different statistical measures on a per pixel basis to amplify groundwater discharge induced thermal anomalies. The results reveal that the range and standard deviation of the data series perform best in terms of anomaly amplification and spatial correspondence to in-situ determined spring dis-charge locations. I conclude on the reason that both mirror temperature variability that is stabilized and therefore smaller at areas where spatio-temporal constant groundwater discharge occurs. 3) The application of the before developed method on a thermal satellite data set spanning the years 2000 to 2011 enables to localise specific groundwater discharge sites and to semi-quantitatively analyse the temporal variability of the thermal anomalies (termed groundwater affected area - GAA). I identify 37 groundwater discharge sites along the entire Dead Sea coastline that refine the so far coarsely given spring areas to specific locations. All spatially match independent in-situ groundwater discharge observations and additionally indicate 15 so far unreported discharge sites. Comparing the variability of the GAA extents over time to recharge behaviour reveals analogous curve progressions with a time-shift of two years. This observation suggests that the thermally identified GAAs directly display the before only assumed groundwater discharge volume. This finding provides a serious alternative to monitor groundwater discharge over large temporal and spatial scales that is relevant for different scientific communities. From the results I furthermore conclude to observe the before only assumed and modelled groundwater discharge share from flushing of old brines during periods with an above average Dead Sea level drop. This observation implies the need to not only consider discharge from known terrestrial and submarine springs, but also from flushing of old-brines in order to calculate the total Dead Sea water budget. 4) I present a complementary airborne thermal data set recorded in 01/2011 over the north-western part of the Dead Sea coast. The higher spatial resolution allows to refine the satellite-based GAA to 72 specific groundwater discharge sites and even to specify the so far unknown abundance of submarine springs to six sites with a share of <10 % to the total groundwater discharge. A larger contribution stems from newly iden-tified seeping spring type (24 sites) where groundwater emerges diffusively either ter-restrial or submarine close to the land/water interface with a higher share to the total discharge than submarine springs provide. The major groundwater contribution origi-nates from the 42 identified terrestrial springs. For this spring type, I demonstrate that 93 % of the discharge volume can be modelled with a linear ordinary least square re-gression (R2=0.88) based on the thermal plume extents and in-situ measured discharge volumes from the Israel Hydrological Service. This result implies the possibility to determine discharge volumes at unmonitored sites along the Dead Sea coast as well that can provide a complete physically-based picture of groundwater discharge magni-tude to the Dead Sea for the first time.:1 Introduction 1.1 Remote sensing applications on groundwater 1.1.1 Classical aspects 1.1.2 Modern aspects 1.2 Motivation and main objectives 1.3 Why the western catchment of the Dead Sea? 1.4 Overview 2 The western catchment of the Dead Sea 2.1 Geological and Structural Overview 2.2 Groundwater system 2.3 Groundwater inputs 2.4 Dead Sea 3 Groundwater flow-paths 3.1 Prologue 4 Method development for groundwater discharge identification 4.1 Prologue 5 Localisation and temporal variability of groundwater discharge 5.1 Prologue 6 Qualitative and quantitative refinement of groundwater discharge 6.1 Prologue 7 Conclusion and Outlook 7.1 Main results and implications 7.2 Outlook References Appendi

Monitoring and modelling volcanoes with assessment of their hazards by means of remote sensing and analogue modelling

Many active volcanoes in developing countries are poorly-known and not monitored. This thesis investigates low cost solutions to map the topography, to identify hazards and to document the eruptions at volcanoes with satellite data. Using a combination of remote sensing techniques and analogue modelling, this thesis also contributes to the understanding of volcanic processes such as the controls upon the 3D shape of sub-volcanic intrusive systems, upon the location of eruption outbreaks, upon the variations in eruption intensity through time and upon the transition between contrasted eruptive styles at a single volcano. After reviewing previous applications of low cost remote sensing in volcanology, the accuracy of two topographic datasets derived from contrasted remote sensing data (ASTER and SRTM) is assessed for volcanic terrains. Oldoinyo Lengai, a natrocarbonatite stratovolcano in Tanzania, is used as an illustrative example of poorly-known volcanoes whose hazards need to be assessed and whose eruptive activity has to be monitored. Satellite images enable mapping, constraining volumes and characterizing surface features of three flank collapses and their associated deposits. An existing numerical model is applied to constrain the emplacement dynamics and the velocity of one of those debris avalanche flows. An algorithm is then presented to retrieve daily information about eruptive activity and its variation over an 8-year period using nighttime MODIS satellite data. Analysis of this time series enable to highlight the control of Earth tides on the timing of high intensity eruptions. The same algorithm, combined with field data and petrologic analyses, is used to document a voluminous lava flow eruption that occurred at Oldoinyo Lengai at the end of March 2006, providing insights into the structure of the shallow plumbing system of the volcano. Satellite data are finally combined with laboratory experiments simulating magma propagation in the Earth crust with sand and syrup or gelatin and water, to provide a better understanding of the control exerted by volcanic edifice load upon magma ascent. These experiments also enable to explain the links between magma ascent, volcano load, sub-volcanic intrusions, volcano surface deformation and location of volcanic vents at the base of large volcanoes

Site and Basin Effects on Seismic Hazard in Indonesia:Sulawesi and Jakarta Case Studies

Earthquakes are among the most costly, devastating and deadly natural hazards. The extent of the seismic hazard is often influenced by factors like the source location and site characteristics, while the susceptibility of assets is influenced by the population density, building design, infrastructure and urban planning. A comprehensive knowledge of the nature of source and local geology enables the establishment of an effective urban planning that takes into account the potential seismic hazard, which in turn may reduce the degree of vulnerability. The first probabilistic seismic hazard assessment (PSHA) incorporating the effects of local site characteristic for the island of Sulawesi in Indonesia has been conducted. Most of the island, with the exception of South Sulawesi, is undergoing rapid deformation. This leads to high hazard in most regions (such that PGA > 0.4g at 500 year return period including site effects) and extremely high hazard (like PGA > 0.8 g at 500 year return period) along fast-slipping crustal fault. On the other hand, a distant site relative to fault might suffer higher ground motion if that site is composed of soft soil. This research has proven that incorporating near-surface physical properties, in this case is represented by VS30, surface geology contribute significantly to ground motions, consequently, responsible for potential building damage. The PSHA study that took place in Sulawesi took us move further, investigate the effect of deep structure on seismic waves. Jakarta was chosen for its location sitting on less known deep sediment basin and economic and political importances. A dense portable-seismic-broadband network, comprising 96 stations, has been operated within four months covering the Jakarta. The seismic network sampled broadband seismic-noise mostly originating from ocean waves and anthropogenic activity. We used Horizontal-toVertical Spectral Ratio (HVSR) measurements of the ambient seismic noise to estimate the fundamental-mode Rayleigh wave ellipticity curves, which were used to infer the seismic velocity structure of the Jakarta Basin. By mapping and modeling the spatial variation of low-frequency (0.124{0.249 Hz) HVSR peaks, this study reveals variations in the depth to the Miocene basement. To map these velocity profiles of unknown complexity, we employ a Transdimensional-Bayesian framework for the inversion of HVSR curves for 1D profiles of velocity and density beneath each station. The inverted velocity profiles show a sudden change of basement depth from 400 to 1350 m along N-S profile through the center of the city, with an otherwise gentle increase in basin depth from south to north. Seismic wave modelings are conducted afterward and shows that for very deep basin of Jakarta, available ground motion prediction equation (GMPE) is less sufficient in capturing the effect of basin geometry on seismic waves. Earrthquake scenario modeling using SPECFEM2D is performed to comprehend the effect of deep basin on ground motions. This modeling reveals that the city may experience high peak ground velocity (PGV) during large megathrust earthquake. The complexity of the basin is responsible for magnifying ground motions observed in the basin

Geotechnical Engineering for the Preservation of Monuments and Historic Sites III

The conservation of monuments and historic sites is one of the most challenging problems facing modern civilization. It involves, in inextricable patterns, factors belonging to different fields (cultural, humanistic, social, technical, economical, administrative) and the requirements of safety and use appear to be (or often are) in conflict with the respect of the integrity of the monuments. The complexity of the topic is such that a shared framework of reference is still lacking among art historians, architects, structural and geotechnical engineers. The complexity of the subject is such that a shared frame of reference is still lacking among art historians, architects, architectural and geotechnical engineers. And while there are exemplary cases of an integral approach to each building element with its static and architectural function, as a material witness to the culture and construction techniques of the original historical period, there are still examples of uncritical reliance on modern technology leading to the substitution from earlier structures to new ones, preserving only the iconic look of the original monument. Geotechnical Engineering for the Preservation of Monuments and Historic Sites III collects the contributions to the eponymous 3rd International ISSMGE TC301 Symposium (Naples, Italy, 22-24 June 2022). The papers cover a wide range of topics, which include: 　 - Principles of conservation, maintenance strategies, case histories - The knowledge: investigations and monitoring - Seismic risk, site effects, soil structure interaction - Effects of urban development and tunnelling on built heritage - Preservation of diffuse heritage: soil instability, subsidence, environmental damages The present volume aims at geotechnical engineers and academics involved in the preservation of monuments and historic sites worldwide

Mesure de déformation par interférométrie radar : développements méthodologiques et applications à la subduction chilienne.

The work of this thesis had two main objectives : on the one hand, develop methodological tools in order to improve InSAR processing in natural setting, allowing the quantification of large-scale deformation ; on the other hand, to apply these techniques to the Chilean subduction zone, one of the fastest in the world, especially in an area with a singular behavior and a limited instrumentation. The effort on the methodological part was the improvement of the algorithmic chain NSBAS, created in the laboratory of geology of the ENS. This one, which uses small basline methods, aims to automate the interferometric processing, from SAR acquisition to time series, including various types of phase correction. One of them was proposed in this thesis in order to reduce topographic effects induced by limits on the resolution of the DEM. The algorithm was developed to perform a local DEM error correction, based in particular on so-called reference points. Regarding the part dedicated to the study of the Chilean active margin, at the origin of an important seismic activity producing large earthquakes above magnitude 7 every year, we look at an area between Taltal (-25°S) and Constitution (-35°S), including the Chilean "Little North". This region is particularlty interesting because it accommodated tectonic deformation related to convergence since the mid-twentieth centuries without causing a large earthquake during this period. We processed 4 parallel tracks, from ENVISAT and ERS satellites, which allowed us to constrain the deformation field on a set of time series. Thus, the main contributions of this thesis are from different order. The algorithm for DEM error correction improves the uwnrapping step and allows to use a larger range of perpendicular baseline. The application in Chile caused the study of two seismic events with the Swarm of Copiapo and the intraplate earthquake of Punitaqui, and was used to estimate variation in coupling along our region of interest considered by the study of interseismic deformation. Furthermore, a better understanding of the seismic cycle is an important issue for an accurate estimate of the seismic hazard. Developments and speed increasing of the automatic InSAR processing chains, will become a challenge in view of the flood of data expected in the future.Les travaux menés durant cette thèse ont eu deux objectifs principaux : d’une part, développer des outils méthodologiques qui contribuent à améliorer le traitement InSAR en milieu naturel, et permettant la quantification de déformations à grande échelle ; d’autre part, appliquer ces techniques à la zone de subduction chilienne, l’une des plus rapides au monde, plus particulièrement dans une zone au comportement singulier et où l’instrumentation est limitée. L’effort entrepris sur la partie méthodologique a consisté à apporter des améliorations à la chaîne algorithmique NSBAS, initiée au laboratoire de géologie de l’ENS et poursuivie au cours du projet EFIDIR. Celle-ci, qui utilise les méthodes à petite ligne de base, a pour but d’automatiser le traitement interférométrique, de l’acquisition SAR jusqu’à la série temporelle, en y incorporant divers types de corrections de phase. L’une d’entre elles a été proposée durant cette thèse pour réduire les effets topographiques induits par la précision du MNT. L’algorithme qui a été développé effectue une correction locale de l’erreur de MNT, en se basant notamment sur des pixels de référence. En ce qui concerne la partie dédiée à l’étude de la marge active chilienne, qui est à l’origine d’une activité sismique de grande ampleur puisqu’elle produit un séisme de magnitude supérieure à 7 tous les ans, nous nous sommes intéressés à une zone comprise entre Taltal (-25°S) et Constitution (-35°S) comprenant entre autres "le petit Nord" chilien. Cette région revêt un intérêt tout particulier en ayant accommodé la déformation tectonique liée à la convergence depuis la moitié du XXème siècle sans pour autant avoir provoqué de grandes ruptures durant cette période. Nous avons ainsi traité 4 tracks parallèles, provenant des imageurs ENVISAT et ERS, qui nous ont permis de contraindre le champ de déformation sur un ensemble de séries temporelles. Les principales contributions de cette thèse sont donc de différentes sortes. L’algorithme de correction de l’erreur de MNT permet d’améliorer l’étape de déroulement et d’utiliser une gamme de lignes de base perpendiculaires plus importante. L’application qui a été faite sur le Chili a occasionné l’étude de deux événements sismiques avec l’épisode de Swarm de Caldera et la séquence de Punitaqui, et a permis d’estimer les variations de couplage de la région considérée par l’étude de la déformation intersismique. À terme, la meilleure connaissance du "cycle sismique" est un des enjeux importants pour une estimation plus précise de l’aléa sismique. Quant aux développements des chaînes de traitement InSAR automatiques et de plus en plus rapides, ils deviennent un défi à relever dans la perspective du flot de données attendu dans le futur (lancement Sentinel en 2013)

Remote Sensing of Earth Resources (1970 - 1973 supplement): A literature survey with indexes. Section 2: Indexes

Documents related to the identification and evaluation by means of sensors in spacecraft and aircraft of vegetation, minerals, and other natural resources, and the techniques and potentialities of surveying and keeping up-to-date inventories of such riches are cited. These documents were announced in the NASA scientific and technical information system between March 1970 and December 1973