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  • 1
    Publication Date: 2017-04-04
    Description: We study land subsidence processes and the associated ground fissuring, affecting an active graben filled by thick unconsolidated deposits by means of InSAR techniques and fieldwork. On 21 September 2012, Ciudad Guzmán (Jalisco, Mexico) was struck by ground fissures of about 1.5 km of length, causing the deformation of the roads and the propagation of fissures in adjacent buildings. The field survey showed that fissures alignment is coincident with the escarpments produced on 19 September 1985, when a strong earthquake with magnitude 8.1 struck central Mexico. In order to detect and map the spatio-temporal features of the processes that led to the 2012 ground fissures, we applied InSAR multitemporal techniques to process ENVISAT-ASAR and RADARSAT-2 satellite SAR images acquired between 2003 and 2012. We detect up to 20 mm/year of subsidence of the northwestern part of Ciudad Guzmán. These incremental movements are consistent with the ground fissures observed in 2012. Based on interferometric results, field data and 2D numerical model, we suggest that ground deformations and fissuring are due to the presence of areal subsidence correlated with variable sediment thickness and differential compaction, partly driven by the exploitation of the aquifers and controlled by the distribution and position of buried faults.
    Description: Published
    Description: 8610-8630
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: JCR Journal
    Description: open
    Keywords: InSAR ; ground subsidence ; buried faults ; ground fissuring ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2023-01-24
    Description: Abstract
    Description: The Dec 22nd 2018 flank collapse and tsunami at Anak Krakatau in Indonesia is a key event in geosciences as little is known about the lead-up processes and deformation changes prior to flank failure. We processed Sentinel-1 satellite radar data in both ascending (orbit 171) and descending (orbit 47) acquisition using multi-temporal InSAR with the Small BAseline (SB) method during the 4 years prior to the collapse. The data shows that the flank was already moving for years prior to collapse, demonstrating that developing instability in volcano can be monitored long before a collapse. The southwest flank movement rates averaged approx. 27 cm/yr, but underwent intermittent accelerations coinciding with distinct intrusion events in Jan/Feb 2017 and in Jun 2018. The data archived here supplements the material detailed in Zorn et al. (202X, https://doi.org/XXXXX).
    Description: Methods
    Description: We processed the displacement flank evolution at Anak Krakatau using multi-temporal InSAR technique and exploited the Sentinel-1 data in both ascending (orbit 171) and descending (orbit 47) acquisition orbit in the period between 08th Oct 2014 and 19th Dec 2018. We adopted the Small BAseline (SB) method as implemented in the ENVI SARscape® software, using standard processing methods (Berardino et al., 2002). SB allows for a maximisation of the spatial and temporal coherence, and therefore maximises the displacement measurements over the flank, owing to the combination of interferograms with small normal and temporal baselines. We generate interferograms connecting each image with two previous and two following acquisitions. The original data has been multi-looked resulting in a pixel size of 15 m. We used the 30m resolution Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) via the Earth Resources Observation And Science (EROS) Center 2017 to remove the topographic component from the interferograms and we filter the results using Goldstein filter (Goldstein and Werner, 1998) with tile sizes of 18×18px. Finally we unwrap the interferograms masking out coherence lower than 0.2 and applying two-dimensional phase unwrapping algorithm Snaphu and we refer to the displacement measurement using a reference point located on the most northern part of the island considered stable (Fig. 2A). The final results are 1D displacement maps in ascending and descending line-of-sight (LOS). Due to a significant increase in eruptive activity of Anak Krakatau beginning towards the end of May 2018, coherence was significantly reduced on the SW-flank and many unwrapped points became unreliable and had to be filtered out. To capitalise on the previously better coverage, we split our analyses into two separate datasets, one (short) for interpreting data before the 29th May 2018, containing more reliable points on the SW-flank, and one (full) dataset with fewer points used to interpret activity after.
    Keywords: InSAR ; Volcano flank instability ; Anak Krakatau ; Collapse Hazard ; Monitoring ; Earth Observation Satellites 〉 Sentinel GMES ; EARTH SCIENCE 〉 SOLID EARTH 〉 GEOMORPHIC LANDFORMS/PROCESSES 〉 TECTONIC LANDFORMS 〉 VOLCANO
    Type: Dataset , Dataset
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  • 3
    Publication Date: 2023-11-14
    Description: Abstract
    Description: Interferometric East and Up rate maps based on time-series analysis of ~5 years of Sentinel-1 radar data provide an unprecedented spatial (~400 m) resolution of the recend surface deformation of the Tajik fold-and-thrust-belt and the greater Pamir area. Among other the data exhibit E-W shortening in the fold-thrust-belt, slip activity of the Babadag thrust fault and the Ilyak strike-slip fault, westward Pamir escape tectonics, halokinesis and near-surface, water-driven effects. Observations and methodology are discussed at length in Metzger et al., 2021 (under Review).
    Description: Methods
    Description: Pre-processed interferograms of 13 Sentinel-1 radar frames serve as the input data for a framewise small-baseline time-series analysis using the LiCSAR/LiCSBAS data processing chain (Lazecky et al., 2020, Morishita et al., 2020). The resulting rate maps in line-of-sight were first tied to the Eurasian-fixed reference frame spanned by available regional GNSS data. If data from two view directions were available, they were decomposed in east and up by fixing the north rates to the interpolated GNSS north rates (Ou, 2020).
    Description: TableOfContents
    Description: The zip-folder contains 1) the framewise rates and uncertainties and corresponding line-of-sight (LOS) information, all labelled by frame numbers, 2) the interpolated north rates based on Eurasian-fixed GNSS and 3) the concatenated and decomposed east and up rates in a Eurasian-fixed reference frame. A GMT script (Wessel & Smith, 2013, v6.0.0) and corresponding Figures serve as an example on how to plot the data.
    Keywords: InSAR ; LiCSBAS ; LiCSAR ; time-series analysis ; NSBAS ; line-of-sight (LOS) ; Earth Remote Sensing Instruments 〉 Active Remote Sensing 〉 Imaging Radars 〉 SENTINEL-1 C-SAR ; EARTH SCIENCE 〉 SOLID EARTH 〉 TECTONICS 〉 NEOTECTONICS ; EARTH SCIENCE 〉 SOLID EARTH 〉 TECTONICS 〉 PLATE TECTONICS 〉 CRUSTAL MOTION ; EARTH SCIENCE 〉 SOLID EARTH 〉 TECTONICS 〉 PLATE TECTONICS 〉 FAULT MOVEMENT ; EARTH SCIENCE 〉 SOLID EARTH 〉 TECTONICS 〉 PLATE TECTONICS 〉 FOLDS ; EARTH SCIENCE 〉 SOLID EARTH 〉 TECTONICS 〉 PLATE TECTONICS 〉 PLATE BOUNDARIES ; Navigation Platforms 〉 GPS (Global Positioning System)
    Type: Dataset , Dataset
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