http://wgstrom.gsenergy.io/sonata-no-19-in-c.php Paper 61 - Session title: Poster Session 1.
Business on a warm night early last week was surprisingly good. The relation between the ray traced GNSS signals and the distance travelled inside each voxel allows to estimate the mean water vapour content in all voxels. In the Xizang area in Tibet we study the April 7, Mw 6. Olympic passenger list, alien passengers arriving in Southampton from New York, 06 The nearly simultaneous analysis of the above Syrian sites is allowing the project: i to acquire a consistent image dataset to understand patterns and trends of looting in Syria and ii evaluate whether the ST technology developed by DLR can be used for such type of assessment to provide updated and detailed knowledge basis to national and international organizations of cultural heritage protection. Mitre, , Barcelona, Spain from "cardiac collapse.
Tapete has aimed to demonstrate the scientific potential of the new TerraSAR-X Staring Spotlight mode ST to support cutting-edge research and real-world applications of damage assessment, looting monitoring and prospection of archaeological features in semi-arid environments, with test sites in Syria. In light of the unprecedented imaging capability with azimuth resolution of up to 0. For the first time, building upon the methodology by Tapete et al. Since October an experimental campaign is being carried out over the Hellenistic site of Apamea inscribed on the UNESCO Tentative List and thousands of looting holes have been observed every two months, by distinguishing those due to new looting and those as an alteration e.
To follow on from this initial experimental phase, the project is now looking at applying this methodology to the Syrian World Heritage Sites of Aleppo and Bosra and other sites across the country where evidence of archaeological looting has been found and documented. The nearly simultaneous analysis of the above Syrian sites is allowing the project: i to acquire a consistent image dataset to understand patterns and trends of looting in Syria and ii evaluate whether the ST technology developed by DLR can be used for such type of assessment to provide updated and detailed knowledge basis to national and international organizations of cultural heritage protection.
Archaeological Prospection, 20 2 , — Remote Sensing of Environment 42— Paper 65 - Session title: Poster Session 1. InSAR Synthetic Aperture Radar Interferometry , with the advantages of high efficiency, wide coverage and low cost, is a key technology for surface deformation survey in recent years. In this study, the small differential deformation of the main 3 NNE active faults in Tangshan urban area is monitored.
Two kinds of radar data are used with the coherent target analysis method. According to the deformation velocity of the coherent points, a deformation profile line nearly orthogonal to fractures and a fitting line of coherent points group in buffer area are analyzed. The results show:. On the contrary, the coherence of SAR image decreases with a longtime, and the 3 faults are close.
In city region, human activities, ground covers influence are resulting difficulty in distinguishing faults deformation. So, InSAR measuring results cannot directly determine the deformation of the fault activity, should be jointed other sources to monitoring the faults activities.
Paper 67 - Session title: Poster Session 1.
Tuesday - Postseismic deformation of the Mw 6. On 3 July , a Mw 6. The event caused at least four deaths, 48 injuries and hundreds of building collapses. The results show that the displacement in radar line of sight is about 2 cm around the epicenter during the period and decays with time. The observed surface displacements are consistent with afterslip on the shallow part of the coseismic fault plane, which indicates that the unreleased accumulated strain energy during the event is released by the afterslip.
Paper 68 - Session title: Poster Session 1. Tuesday - The mechanism of partial rupture of a locked megathrust: The role of fault morphology. Assessment of seismic hazard relies on estimates of how large an area of a tectonic fault could potentially rupture in a single earthquake. Vital information for these forecasts includes which areas of a fault are locked and how the fault is segmented. Much research has focused on exploring downdip limits to fault rupture from chemical and thermal boundaries, and along-strike barriers from subducted structural features, yet we regularly see only partial rupture of fully.
Here we draw insight into this conundrum from the 25 April Mw 7. The morphological bounds explain why the event ruptured only a small piece of a large fully locked seismic gap. We then use dynamic earthquake cycle modeling on the same fault geometry to reveal that such events are predicted by the physics. Depending on the earthquake history and the details of rupture dynamics, however, great earthquakes that rupture the entire seismogenic zone are also possible. These insights from Nepal should be applicable to understanding bounds on earthquake size on megathrusts worldwide.
Paper 69 - Session title: Poster Session 1. However, groundwater levels have reduced in recent decades as the population increases and rainfall decreases. Ground-based surveys are limited to discrete points or traverses across parts of the metropolitan area and therefore do not reveal the full extent of deformation. Between August and May , Sentinel-1A data were acquired over Perth in an ascending orbit at 24 day intervals.
Time-series analysis shows that displacements observed at wetlands are temporally correlated with changes in groundwater levels in the superficial aquifer. Since the commissioning of Sentinel-1B, the Perth Basin is expected to be consistently imaged from a descending orbit at 12 day intervals. These observations will provide a longer InSAR time-series, which is required to determine whether the measured displacements are representative of long-term deformation or more likely seasonal variations.
Paper 72 - Session title: Poster Session 1. Space-based Synthetic Aperture Radar interferometry InSAR applications have been widely used for monitoring the cryosphere over past decades. Due to temporal decorrelation, interferometric coherence often degrades severely on fast moving glaciers and sea-ice. In addition, higher sensitivity ambiguity by large baseline configurations, which are needed for extracting topographic information over low relief areas such as sea-ice surfaces.
TanDEM-X observations, which overcome the temporal decorrelation due to its simulatanious measurements by its two sattelite constellation, has used short baseline of m to m which are sufficient for generating excellent DEM in most locations around the world. However, it is still difficult to estimate detail topographic characteristics over low slope sea-ice or glacier surfaces due to relatively less sensitive height ambiguity from small baselines.
In this study, we use the TanDEM-X large baseline formation following scientific phase timeline to generate high spatial and sensitive topographic elevation model for glaciers and sea-ice. We obtained seven TanDEM-X bistatic and pursuit monostatic mode observations of glaciers and sea-ice located in both Greeland and Antarctica. As expected, coherent interferometric phases 0. The height ambiguity of the datasets are ranged from 7. Because of high sensitive ambiguity, we can extract detailed geomorphological features like surface roughness on sea-ice and glaciers.
High resolution interferometric phase including topographic information is also useful for separating iceberg from sea-ice or open water. Both observations show very good correlation with a few meters of offsets, which can be used for calibrating TanDEM-X topography. Routine TanDEM-X observations will be very useful for understanding better the dynamics of sea-ice and glacier movements.
Paper 73 - Session title: Poster Session 1. Wetland Interferometric Synthetic Aperture Radar InSAR is a unique application of the InSAR technique, which detects water level changes in aquatic environments with emergent vegetation at high spatial resolution over wide areas . The Everglades, which is a World Heritage Site, is the largest natural region of subtropical wilderness in the United States. Both wetlands have been threatened by severe environmental stresses induced by anthropogenic activities, as agricultural development and urban expansion, as well as by natural causes, such as sea level rise and climate change.
With the recognition of their ecological importance, various restoration plans have been authorized to preserve and restore these invaluable wetland ecosystems. Due to the vast extent and remoteness of these wetlands, monitoring their ecological and hydrological conditions are best conducted using remote sensing observations. Because recently the Sentinel-1B has been launched successfully in orbit with phase continuity of the Sentinel-1A, only 6-day interferometric temporal baseline can be utilized for the wetland InSAR application.
Moreover, the 6-day or day repeat pass observations of Sentinel-1 provide a great advantage for maintaining higher interferometric coherence over wetlands, which their vegetated environment induces rapid temporal decorrelation. We processed this pair using the Gamma software, which generates differential interferograms and eliminates topographic effects using a digital elevation model DEM. We also used multi-looking and phase filtering to enhance the signal to noise ratio.
The preliminary interferograms show an overall low gradient fringes over the CGSM wetlands, which are mainly covered with herbaceous vegetation. Because a man-made road across the wetland blocked a natural hydrologic environment between see and fresh water at the CGSM, ecological catastrophes were occurred . This ecological disturbance caused the hyper saline conditions resulting in massive mortality of mangroves at the end of the 20 th century.
It is interesting to note that coherent phase is better maintained over dead or rehabilitated mangrove areas than over live mangrove areas. It might be resulted from that leafy and heavy mangrove forest prevents the radar signal from maintaining coherence. Because volume scattering in heavy vegetated area does not allow maintaining coherence over time. The low coherence indicates that the mangrove forest at CGSM is tall and massive, because small and intermediate height mangrove forests yield coherent phase, as we observed in the Everglades wetlands .
We will continue evaluating the Sentinel-1 IW interferograms with in-situ observations from water level stage stations. Furthermore, the planned frequent data acquisition of every repeat cycle 6 or 12 days will provide us new understanding of the hydrological conditions and their changes over time at the entire wetland scale. Hong, A. Mulcan, and B. Brisco, Remote sensing monitoring of tide propagation through coastal wetlands, Oceanography : 26 3 —69, DOI Paper 76 - Session title: Poster Session 1.
Landfast sea ice, called fast ice for short, is a type of sea ice that is attached to the coastline or ice shelves. Strain of fast ice is indicates its dynamics that has large influences on the variability of polynya, marine ecosystem and logistics for research stations near the coast. Therefore, it is important to accurately measure the strain of fast ice. We assumed that the axial direction of glacial strain is perpendicular to the side of CGT while that of tidal strain is perpendicular to its hinge line, by analyzing ice flow of CGT, geometry of TNB and tidal bending characteristics of fast ice and CGT.
The glacial strain represented that fast ice in the east and west of CGT experienced the deformation by shearing. The shearing deformation of the fast ice decreased as the distance from the edge of CGT increases. The one-day InSAR-derived glacial strains were little deviated from those estimated from 57 weekly 18 seven-days and 39 eight-days, respectively InSAR images in which glacial strain of fast ice was observed dominantly due to cumulative flow of CGT and oscillating tide height.
Magnitudes of the one-day InSAR-derived tidal strain of the fast ice were strongly correlated with those of the tide variation during the observations. Fast ice isolated from CGT by cracks and leads showed tidal strain only because glacial stress was not reachable. Paper 77 - Session title: Poster Session 1. It is essential to monitor mining-induced three-dimensional 3-D time-series displacements, in order to assess mining-related geo-hazards and understand the dynamics of mining subsidence.
However, due to the side-looking imaging geometry of current SAR sensors, the deformation provided by interferometric synthetic aperture radar InSAR is one-dimensional 1-D i. Nevertheless, this is difficult to be met because of the limited number of available SAR sensors. We present a method for mapping 3-D time-series displacements of coal mining areas using a single geometry SAR dataset in this paper. The horizontal motion and the gradient of vertical subsidence caused by underground extraction is usually proportional to each other.
Consequently, the multi-temporal observations of the vertical subsidence are obtained from the available InSAR pairs generated by the single geometry SAR acquisitions. Afterwards, an interferometric coherence-based weighted least square method is applied to estimate the time series of the mining-induced vertical subsidence from the SPI-derived multi-temporal observations. Having obtained the time-series vertical subsidence, the horizontal motions in the easting and northing directions are accordingly determined, on the basis of the proportional relationship between the horizontal displacement and the gradient of vertical subsidence in mining areas.
The results show that the maximum 3-D displacements in this period reach up to 0. Paper 80 - Session title: Poster Session 1. Indonesia is periodically affected by severe volcanic eruptions and earthquakes, which are geologically coupled to the convergence of the Australian tectonic plate beneath the Sunda Plate. SAR interferometry InSAR can be used to support studying and modeling of terrain movements such as tectonic motions associated with faults.
Multi-temporal InSAR MTI techniques provide both mean displacement maps and displacement time series over selected, stable objects on the Earth surface. The study of tectonic phenomena requires large-scale spatial analysis that poses challenges in MTI processing. A reliable modeling needs additional information coming e. This work is aimed at performing an analysis of ground displacements over Indonesian sites through MTI techniques.
Based on the existence of i onshore active faults, ii undergoing deformation as from GPS data, iii foreseen good interferometric coherence, iv availability of SAR imagery, two stacks of COSMO-SkyMed data, both acquired in stripmap mode between and , have been selected, one on the capital Banda Aceh descending geometry, mean incident angle of For each station, horizontal velocity values and displacement time series are available. Sentinel-1 data are also available, even though their number is quite limited between 20 and 30 because of the reduced acquisition frequency.
Nevertheless, Sentinel-1 acquisition geometries on the two test sites are complementary to those of the COSMO-SkyMed data, thus allowing in principle the combination of InSAR-based displacement maps derived from different viewing geometries. The former is well suited for scarcely urbanized areas and high resolution local scale analysis, while the latter has been proven effective for studying both volcanic deformations and fault slips.
This processing strategy also allows us to cross-validate MTI results. Paper 87 - Session title: Poster Session 1. A sequence of earthquakes has hit the Centre Italy starting from August and still continuing up to now. The quakes have affected the regions of Lazio, Umbria and Marche with the destruction of small villages in the Apennines mountains. An in-situ inspection has registered relative displacements of the main faults in the area in the order of a few centimetres. Synthetic Aperture Radar SAR interferometry is already a mature technique to map such terrain displacements over large regions.
In fact, starting from the very beginning many research group have made available to the general public maps of earthquake-induced terrain displacements using both X-band Cosmo-Sky-Med and C-band Sentinel-1 SAR images provided by the Italian and the European Space Agencies, respectively. In this work we study the problem of estimating the phase delay due to the propagation of SAR signal in neutral component of atmosphere. This delay is mainly related to temporal and spatial variations of water vapour spatial distribution in the atmosphere.
This is an open issue in SAR interferometry and is of crucial importance when using only an interferogram and not a time series as in the case of earthquake when terrain displacements are measured by processing two SAR images, one before one after the seismic event. In this work we show the SAR interferograms of the seismic event before and after the mitigation of atmospheric phase delay.
The mitigation procedure is based on the use of the WRF model. The impact of assimilating estimates of atmospheric phase delay from in-situ measurements and spaceborne data into the WRF model is also investigated. The earthquake of 31st of October has been chosen as a case study since it has the been the strongest one in the sequence of seismic events. Four couples of Sentinel-1 SAR images have been used to generate four independent coseismic interferograms, along both ascending and descending orbits.
WRF data have been generated for each of the eight SAR images used to generate the four interferograms. Starting from the WRF output synthetic maps of atmospheric phase delay have been generated and used to mitigate the atmospheric phase delay effects in the four interferograms. Since the four interferograms refer to the same seismic event it is expected that the corresponding geolocated terrain displacement patterns be in agreement each other if the displacement is purely vertical.
However, differences are observed mainly due to the different propagation delays in atmosphere. A statistical analysis of terrain displacement patterns before and after mitigation of atmospheric propagation delays is carried out to quantify the performances of the mitigation procedure. Nico, R.
Remote Sens. Mateus, G. Nico, J. Paper 89 - Session title: Poster Session 1.
Tuesday - Merging the Sentinels and Landsat to provide evidence base maps of green infrastructure in UK cities. In the last 15 years, Green Infrastructure GI defined as a network of multifunctional green spaces, urban, rural and water has increasingly got higher priority on the urban agenda. City councils in the UK frequently underpin their green space strategies using evidence base maps that show where there is environmental, social, economic and cultural potential for GI to deliver public benefits across their administrative boundaries.
Although these maps are factual and based on inventoried green space, they may have the limitation of providing a static snapshot of the GI situation at a specified time. Therefore they do not necessarily capture the dynamic changes of GI within the urban footprint and, more importantly, along the rural-to-urban fringes where opportunities for urban development can manifest. This paper presents how the freely accessible regular acquisitions from the European Space Agency ESA Sentinel satellites can be used, in conjunction with Landsat time series, to create, and keep updated, maps showing the spatial distribution of GI and their changes in land cover and land use as a result of urban development projects.
Sentinel-1 acquired in spring and autumn sessions in were classified by testing the different properties of the SAR images, including the dual polarization VV and VH, and their temporal changes. The GI polygons extracted from the supervised classification were then merged with those extracted from simultaneous Landsat acquisitions to produce a GI layer covering the West Midlands region. Matching the geometric accuracy of 50 m of the geological datasets held by the British Geological Survey, this evidence base map is suitable for geospatial analysis of GI against the properties of the subsurface.
Where correlation is found with the properties of the ground, this is translated into geological opportunities for the installation of new GI or constraints for existing GI to function as intended. The discussion will focus on how this type of product can be interrogated by city stakeholders and, alongside economic and social considerations, used to feed into the GI strategic planning at city scale level.
Paper 92 - Session title: Poster Session 1. A comprehensive and detailed deformation monitoring for airports is sometimes difficult to achieve by traditional surveying technologies, as the continuous operating of airports significantly limits the deployment of instruments. Besides, critical areas with obvious subsidence and highly possible in reclaimed airports may be missed by the station-based measurements.
For decades, Interferometric Synthetic Aperture Radar InSAR has seen its effectiveness in wide-range, high-resolution deformation monitoring, which provides detailed up to 1 m spatial resolution and accurate several millimiters or less surface displacements. The persistent scatterers PS perform strong capabilities in man-built areas. Yet, its applications still hold drawbacks in semi-natural and smooth surface with specular reflection characteristics, e. Knowing that the airports are covered not only with artificial structures but also natural surface, e.
To this end, this study intends to accompany the PS targets with distributed scatterers DS that enables the estimation of deformation parameters in a combined way. Basically, the Anderson-Darling test will be used for homogeneous filtering. Phase estimation of DS candidates is to be conducted using a singular value decomposition and coherence-weighted triangulation strategy. SAR data from Sentinel-1 A is intended to be used in this study. Paper 94 - Session title: Poster Session 1. Soil moisture influence on SAR interferometric phase and coherence was first noticed by Gabriel et al.
The most intuitive explanation is related with the expansion of the soil clay due to the presence of water. However, recent investigations have pointed out that the interferometric effect is not due to soil deformation effect. Experimental results has shown that the vertical expansion of soils due to watering is much smaller than the measured phase shift. De Zan et al. The idea behind the model is that the vertical wavenumber is affected by changes on the dielectric proprieties of the soil.
The model was validated with L-band interferometric phases. The test site is a farm on the alluvial plain of the Tagus estuary, close to Lisbon, where four soil moisture sensors were installed. Three sensors were installed 5 cm above the surface and one sensor at 30 cm above the surface providing a measure of the soil moisture depth gradient.
In order to minimize the temporal decorrelation, one interferogram was computed for every two consecutive SAR images and multilooked for speckle noise reduction. Soil moisture measurements were used to predict the analytical interferometric phases and coherences and compared with the measured interferometric phases in both VV and VH polarimetric channels.
Results for the inversion based on phases triplets were also computed for the VV and VH polarimetric channels. Gabriel, A. Mapping small elevation changes over large areas: Differential radar interferometry. B7, P. De Zan, A. Parizzi, P. Prats-Iraola, and P. Paper 98 - Session title: Poster Session 1. In this contribution we will give an overview and demonstration of PyRate , an open source Python software for computing InSAR displacement time series using the short baseline differential InSAR processing strategy.
Many of the processing algorithms in PyRate are based on the Matlab equivalents including the network orbital error estimation, and linear rate map algorithms. As such, the python language has been used in order to provide a portable and cost-free solution to conducting time series analysis that is scalable from desktop machines for small area processing to large multi-node super computers for conducting regional or continental-scale analyses using parallel processing. Furthermore, PyRate follows modern software engineering practices and has been thoroughly unit tested.
We will validate PyRate -derived Sentinel-1 InSAR displacement time series results against results from other software packages and external geodetic data using a case study in the Sydney Basin, Australia. In this region, subsurface longwall coal mining is causing centimetre-level subsidence anomalies at a spatial scale on the order of a kilometre. Currently, a stack of thirty-four Sentinel-1 Interferometric Wide Swath images covering the study region have been acquired with a revisit of 12 days since August GPS-derived coordinate time series from two continuously operating stations recording since July will be used as external validation for the InSAR time series analysis.
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The GPS analysis of the first four months of data indicate that one of these sites is stable within a couple of millimetres whereas the other has already recorded non-linear deformation at the centimetre-level in vertical and horizontal components during the passing of the subsurface longwall operations. We are inviting community participation and collaboration on the testing and further development of PyRate. Feedback on the experiences of users when processing data from different SAR sensors and in different areas of interest will help to focus future development and improvements to the PyRate software.
Paper 99 - Session title: Poster Session 1. Tuesday - Australian experience with Sentinel two earthquake case studies. The use of repeat-pass differential InSAR to quickly identify the extent of surface deformation resulting from crustal earthquakes is now common place in many parts of the world, with many groups providing near-real-time routine processing of freely available Sentinel-1 SAR imagery.
Surface deformation patterns derived in this way can assist emergency response teams to concentrate their recovery efforts on the potentially most damaged regions whilst also assisting field survey teams to focus their resources in the correct area in order to be able to record vital post-event information such as infrastructure damage, surface ruptures and where to deploy temporary ground sites. The Australian continent does record low magnitude M earthquakes on a regular basis, but most are not felt or do not adversely impact the human population.
However, Australia has experienced earthquakes with M6 or greater, with seven such earthquakes recorded since This was the largest earthquake Australia has experienced since The remote location of this earthquake meant that there was no infrastructure damage, but it was felt in the closest township of Yulara. Given the magnitude of this event was an uncommon occurrence, Geoscience Australia GA quickly mobilised a field team to deploy a temporary seismometer network to record aftershocks. Shortly after this event, an earthquake measuring M5. No field team was deployed to Norseman since all resources were already focussed on the earlier Petermann Ranges earthquake.
However, there was interest in studying the surface deformation remotely using InSAR. More often than not in Australia, InSAR cannot be used to attempt to image coseismic deformation of earthquakes due to the lack of pre-earthquake SAR images for the epicentral area.
Several difficulties in processing Sentinel-1 IWS data were encountered that inhibited the rapid production of interferograms for use by the field team. These challenges will be presented in this contribution. The ALOS-2 interferogram revealed a complex surface rupture pattern which helped the field team to focus further mapping efforts. Furthermore, features identified through phase discontinuities and coherence changes correlated with field measurements and high resolution optical imagery.
Once successfully processed, the Sentinel-1 interferogram for the Petermann Ranges earthquake was much more de-correlated than ALOS-2, particularly in the near-field region of the surface rupture. The Sentinel-1A interferogram for the smaller Norseman earthquake exhibited no obvious deformation fringes. This appears to be due to the earthquake occurring too deep and having a magnitude too small to be detected by InSAR. Work is currently being undertaken to develop a fault-slip distribution model for the Petermann Ranges earthquake by conducting a joint inversion of the descending Sentinel-1A and ascending ALOS-2 interferograms, and the results will also be presented in this contribution.
Paper - Session title: Poster Session 1. Tuesday - An improved data integration algorithm applied to the study of the 3D displacement field due to the Napa Valley earthquake. In this work, we propose an improved algorithm to constrain the 3D ground displacement field induced by fast and sudden surface deformation phenomena such as an earthquake or a landslide. Based on the integration of different data, we estimate the three displacement components by solving a function minimization problem from the Bayes theory.
Any other source of information can be added to the processing chain in a simple way, being the algorithm computationally efficient. Furthermore, we use the intensity Pixel Offset Tracking POT to locate the discontinuity produced on the surface by a sudden deformation phenomenon and then improve the GPS data interpolation. This approach allows to be independent from other informations such as in-situ investigations, tectonic studies or knowledge of the data covariance matrix. We applied such a method to investigated the ground deformation field related to the Mw 6.
The SAR satellites require a very good pointing control in order to assure high quality images and good interferometric performances. This is particularly true for modern sensors, implementing advanced acquisition techniques such TopSAR. For this reason modern SAR sensors like Sentinel-1 are equipped with very accurate attitude control systems requiring, after launch, a calibration procedure in order to obtain the expected performances.
The pointing calibration is usually performed during the Commissioning Phase of a SAR mission and involves the usage of Elevation Notches to adjust the roll pointing and of transposers to adjust the yaw and pitch pointing. The main limitation of this strategy is the sparseness of the available calibration sites. Elevation Notches require very homogeneous scenes to be effective and hence shall be performed over the Rain Forest.
On the other hand transponders are expensive and can only be deployed in few calibration sites. This means that possible orbital trends in the sensor pointing errors cannot be captured by the currently used calibration strategy. The present paper focuses on this issue and proposes a new method to perform a full sensor pointing calibration, exploiting the Doppler Centroid estimates from SAR acquisitions over still land areas for yaw and pitch calibration and Permanent Scatterers from SAR interferometric stacks for roll calibration.
The advantage of this calibration technique is that calibration sites from all over the world can be selected in order to get full orbit pointing calibration, fundamental for modern SAR applications. The yaw and pitch calibration is performed exploiting the DC estimates from stationary scenes. The data acquired by space-born SAR satellites are naturally affected by a Doppler shift, due to the relative motion between the platform and the imaged ground scene. Assuming a perfectly calibrated pointing control system such Doppler shift can be fully predicted. The proposed calibration method starts from a grid of DC estimates from the data in the imaged scene and performs a Singular Value Decomposition to identify the pointing plane best fitting the available DC estimates.
The roll calibration is performed through the processing of interferometric stacks exploiting natural PSs. Usage of PSs for radiometric calibration of SAR sensors is a well-known technique allowing to assess long term radiometric stability. Moreover, from a reformulation of the model, it is possible to account for an error in the antenna pointing in elevation and to solve for this by exploiting measures on PSs located all over the swath. The combination of this two calibration methods will allow to get a full 3D sensor calibration.
This process, repeated in time, will allow to identify any possible trend in the sensor pointing which, corrected, will allow to increase the accuracy of the SAR applications. The first part of the paper will introduce the proposed pointing calibration methodologies. Surface elevation changes of an ice sheet characterise its reaction to variations in the regional climate. A warming climate, ultimately causes enhanced surface melting and dynamic thinning of a glacier [van den Broeke et al.
In contrast to classical radar or laser altimeters the differencing of high resolution DEMs can give insight into the spatial extent and pattern of the thinning process. The penetration depth is depending on the dielectric properties of the snow and ice cover and the carrier frequency of the signal [Stiles et al. In case of a wet snow or ice surface this effect can be neglected for both X- and C-band, because the actual signal penetration is much lower than the vertical accuracy of the InSAR DEMs. However, in very cold and dry climate conditions, signal penetration of X- and C-band waves can be in the order of several meters.
One approach to account for signal penetration is the correction of InSAR DEMs with coincident laser altimetry measurements with lower spatial resolution, but no signal penetration. Unfortunately, since the deactivation of ICESat in February , there is no operational laser altimetry satellite in orbit. With the ATM instrument of operation IceBridge, there is only an airborne replacement for a laser altimeter that tracks the actual snow and ice surface. According to [Stiles et al. Prognostication of realistic ground motion that includes absolute amplitudes and the full wave train of arrivals is essential to comprehensively narrate earthquake hazard and can give noteworthy insight into the poorly understood tectonics of the area.
In order to estimate realistic ground motion from probable earthquake, awareness of earthquakes source parameters in area is indispensable. Earthquake source parameters serve as a substantial database for the generalists and synthesizers in seismology and as an initial starting point for the applied theoreticians. The routine determination of source parameters, could make feasible a new level of understanding in many seismological studies that would parallel the use of reported earthquake locations to demonstrate boundaries of tectonic plates. It can provide a wealth of critical information for earthquake hazard assessment and for improved understanding of the earthquake process.
The primary purpose of this study are to: 1 ameliorate estimation of source parameters and computer simulations of earthquakes 2 examine the effect of a range of rupture parameters on synthesized strong ground motion, 3 demonstrate that models derived from step by step modeling of InSAR observation L-band, C-band and X-band respectively , can be used to predict very realistic source parameters. We have used Qeshm earthquake to demonstrate the rich potential of using three InSAR observation sets L-band, C-band and X-band to measure coseismic fault zone deformation and consequently, the causative fault parameters of Qeshm earthquake.
It had a magnitude of 5. It was followed by five aftershocks of M 5. Applying InSAR chain processing for modelling earthquake parameters according to the formulation of Okada, because of covering the wide area, acceptable precision and being inexpensive is highly been considered. Interferometry SAR analysis is especially useful because of its high resolution and precision. Factors that limit InSAR include atmospheric perturbations and that it can only determine one component of displacement in the direction of line of sight.
InSAR has become a commonly used technique to measure surface deformation. Measurements by the SAR satellites are made obliquely below the satellite during both ascending orbits where observations are made from the west and descending orbits where observations are made from the east.
Horizontal deformation therefore causes inconsistencies between ascending and descending interferograms. Differential interferometry aims the measurement of ground deformation using repeat-pass interferometry Hanssen, In this method, we use phase difference of two or more SAR image with same geometry to retrieve deformation phases. In this paper we describe a new approach that allows us to improve the source parameters and simultaneously modify the solution for the moment tensor.
This, in effect, yields the best source parameters, which for major earthquakes need not be the same as the point of initiation of rupture on the surface sometimes it did not reach the surface. In this approach, obtained ranges for each parameters in inversion are used as input ranges for next inversion procedure. For all steps, Marquardt algorithm Marquardt, has used. Marquardt algorithm can be seen as a regularization of the Gauss-Newton method. The steps are based on coverage area with three satellite images and the wavelength of them. The processing began from biggest coverage area and lowest resolution because of higher wavelength.
Thus, in first step L-band inversed and analyzed, then C-band and finally X-band. The output results from first processing including a range for all source parameters, will be initial values as input for next step. Though the source parameters are assumed completely unknown, we must set, for each parameters, a range of values between a minimum and a maximum. In fact, the basic premise for calculating source parameters of an earthquake using InSAR observations will be output results from satellite that has biggest coverage area and higher wavelength.
The coseismic displacement of Qeshm earthquake is modeled via Non-Linear inversions, in order to retrieve the position and parameters of the causative fault. With the Non-Linear inversion, we try to reproduce the observed displacement by means of a geophysical source with unknown parameters and all its parameters must be inferred from InSAR observations. The first search ranges for nonlinear inversion of L-band data were set to 0. Then the resulted ranges for every parameter were used for input parameters of C-band inversions, finally the output results from C-band inversion were used for input parameters of X-band inversion as input ranges.
The mentioned procedure was done to achieve more precise result for source parameters of Qeshm earthquake. The final set parameters for earthquake are: 8. Each of these studies proposes different mechanisms for this earthquake. At last for best comparison between the obtained interpretations with other studies carried out on Qeshm earthquake CMT solution, Nissen report E.
Nissen et al. The best fit between observed and synthetic accelerograms was considered as best report for causative fault parameters of Qeshm earthquake. Strong ground motion data provides researchers with very important information about the rupture processes of earthquakes, simulation of ground motion and consequently source parameters of an earthquake.
In this way, the effects of true earth structure are included in the modeling process and the results are more precisely. The data were recorded by three-component SSA-2 accelerometers with a threshold of 10 Gals at a sampling rate of samples per second. All of components of these data are used in this study.
Simulation of ground motion from large earthquakes using small earthquakes subevents as Green's functions and summing them in a random way is basis of this method. The recording stations were located at epicentral distances ranging from 14 to km. The acceleration records from all components were at first corrected for baseline correction following the algorithm developed by Boore, The final comparison are presented as percentage for accuracy.
These results obtained from comparison between observed and synthetic strong ground motion in two stations Suza and Tomban in three components longitudinal L , vertical V and transverse T components. For this comparison, the maximum absolute value was used for comparing between observed and synthetic acceleration, velocity and displacement data. To compare between Fourier and response spectrum, the correlation of observed and synthetic one was used.
In velocity and displacement, we are faced with variable results for four procedure. At last, overall accuracy with same weighing to each category Acceleration, velocity, displacement, fourier and response specrum for Suza and Tomban stations was calculated. Comparison between observed and synthetic strong ground motion shows that our procedure results more precise source parameters compared with other literatures. Our procedure allow us to move forward from results with larger coverage area and less resolution to greater resolution to obtain greater accuracy for fault parameters.
Jose Alexander Chavez Hernandez 3 e-mail: jalexanderchavez gmail. The city is located in plateau between the San Salvador volcano and IIopango caldera, a region of high seismic activity. The city's average elevation is m a. San Salvador Volcano was dormant since its last eruption in , but has been active recently.
East of the municipality lies the San Jacinto Hill and the caldera of Lake Ilopango, the largest natural body of water in the country with an area of 72 square km. The caldera is seismically active, but has not erupted since The city has suffered from many severe earthquakes, the most disastrous of which occurred in The San Salvador volcano erupted again in ,resulting in three major earthquakes that damaged the city so extensively the government was forced to temporarily move the capital to the city of Santa Tecla known at the time as Nueva San Salvador.
The San Salvador Earthquake struck on October 10, , causing considerable damage to the city and surrounding areas. Between 1, and 1, people are believed to have been killed, and over 10, people were injured. The El Salvador earthquakes struck El Salvador on January 13 and February 13, , resulting in considerable damage to the city, especially in Las Colinas suburb, where a landslide destroyed homes and killed many people.
It has revealed presence of vertical ground deformation. Subsidence is observed mainly within Quaternary silicic volcanic rock, mostly tuffs. Small uplift was confirmed within young Quaternary and mafic volcanic rocks, on the north slope of the San Salvador volcano. The another interesting phenomenon could be observed in northern — central part of the city Department Mejicanos.
Due to the high seismicity of Salvador satellite interferometric monitoring should be continued. Short revisit cycle will improve temporal correlation and increase capabilities of deformation mapping. Combining with ongoing e. In addition, large deformation caused by shallow earthquakes can result in significant decorrelation in the vicinity of the fault rupture, where interferometric phase cannot be revealed properly with a traditional InSAR processing chain. To recover more explicit deformation details, a subpixel-compensate strategy is proposed in gInSAR.
The improved results for the Mw7. This implies the practicability of the proposed strategy for large deformation events. Some of these suggested strategies can also be applicable to other open source InSAR packages. Let us refer to Fig. Firstly, the actual interferograms are obtained by the InSAR system in the real-time processing.
Secondly, the referenced interferograms are generated based on the digital elevation database, flight trajectory and imaging parameters of the InSAR system. Thirdly, the previous two interferograms are matched by Scale-Invariant Feature Transform SIFT algorithm to obtain the location shift in azimuth and range direction. And then we will inverse the position and attitude offset according to the InSAR three-dimensional positioning model and inversion model.
At last, the position and attitude information and the IMU information are set to the combined filter to obtain the navigation output.
It is obvious that the location errors related not only to the platform location, but also to the platform attitude. So we can estimate the position errors and attitude errors by solving nonlinear equations, which are gained through InSAR three-dimensional positioning model and inversion model. We verify the validity of interferogram matching and the inversion of position and attitude by experiment. The results of the experiment are shown in Fig. The interferogram matching result is shown in Fig. Apparently, the differences between the simulated and theoretical result are quite tiny.
Finally, the position and attitude information are inversed through the inversion model in high precision.
The errors of position inversion are less than 2 meter, and the errors of attitude inversion are less than 0. This leads to new applications in time-series analysis and SAR Interferometry InSAR , which make this Synthetic Aperture Radar SAR mission particularly suitable for monitoring geohazards and for rapid mapping activities and to new challenges in handling big data. Based on pairs of Sentinel-1 data from consecutive passes this service provides an interferometric product at m resolution with systematic processing over tectonic areas as defined by the CEOS Working Group of Disasters.
In addition, a 50m resolution product are also delivered to a pre-defined group of expert users working in ESA research and development studies. The focus of this work is to test the synergistic use of amplitude and coherence data of the Sentinel-1 Browse service for disaster monitoring applications in the field of flood mapping, fire detection and earthquake damage assessment. Within this presentation an overview of the main methodological developments in each disaster topic is given and demonstrated in selected test areas:. This extension has been tested on two time-series of 14 and 7 Sentinel-1 acquisitions in flood-affected areas at Evros River at the border between Greece and Turkey and at Shannon River, Ireland, respectively.
While it was not possible to derive the burnt area using the amplitude data in both test sites, a significant loss of coherence over burnt scars between co-event and pre-event data pairs could be identified and used for the extraction of the crisis information. Best results have been achieved by classifying the absolute deviation of the co-event coherence to the mean time series value. Iranian plateau and surrounding areas are affected by the convergence between Arabian and Eurasian plates, where the deformations are accommodated by young Zagros collision, old Alborz and Kopeh Dagh collisions, Makran subduction and shear zones in east Iran.
This variety of deformation makes Iran an ideal natural laboratory for measuring kinematics and dynamic activities. Earthquakes with magnitude greater than 6 caused more than , victims in the last century. This indicates necessity of seismic risk assessment inside Iran. On 20 th December , an earthquake with M w 6. The earthquake epicenter was in a low population area so, luckily, it caused only few casualties.
To study the source parameters of this doublet, Walker et al. In , National Cartography Center NCC of Iran established a geodetic network of 20 stations bedrocks sites with forced antenna centering in the study area. The results of two GPS measurement surveys show a significant post-seismic deformation signal in the area. Considering the active faults distribution, post-seismic deformation retrieved from GPS sites and the 76 aftershocks encouraged us to better investigate and model the post-seismic deformation related to the and earthquakes. Post-seismic studying provides information about rheology of the surrounding region and improves our knowledge about the strain release after the earthquake.
We joined two frames along the same orbit to cover the whole deformation field, resulting in 30 ascending and 30 descending datasets, respectively. We applied the Small Baseline Subset SBAS algorithm for both ascending and descending tracks to obtain the post-seismic mean velocity map and the relative deformation time series. Later, we have modeled the post seismic signal considering a dislocation on a finite fault in an elastic and homogeneous half-space that are the assumptions for the Okada model.
Post-seismic results were modeled adopting a two-step approach: 1 a non-linear inversion was performed to constrain the fault geometry parameters and considering an uniform slip, then 2 a linear inversion was operated to retrieve the slip distribution on the fault plane previously obtained. The best-fit retrieved model for the Rigan strike-slip earthquake shows that the maximum slip is present on the same area interested by the co-seismic slip model, and already described by Walker et al. Tuesday - Time series of surface displacement of Arctic glaciers and ice caps from space-borne SAR data.
In consideration of the strong atmospheric warming that has been observed since the s in polar regions there is a need to quantify ice mass loss of Arctic ice caps and glaciers and their contribution to sea level rise. In polar regions a large part of glacier ablation is through calving of tidewater glaciers driven by ice velocities and their variations. Through frequent monitoring based on repeat satellite data the evolution of Arctic glaciers and ice caps can be now recorded at high temporal sampling.
Complete ice velocity maps of the Svalbard archipelago can be e. Dedicated Sentinel-1 campaigns were also accomplished over the Canadian and Russian Arctic. In our contribution we will present selected results obtained with Sentinel-1 data and highlight significant changes of ice surface velocities evident from the comparison with older maps. The most evident signal over Svalbard is observed for Basin 3 on the Austfonna ice cap, which shows dramatic changes since , but significant accelerations are also depicted on a few other glaciers across the archipelago.
A similar process seems already to have started for the southeastern tip of Austfonna, sometimes called Basin In the framework of a ground based radar campaign in Davos, Switzerland, unexpected fringe-like features, parallel to the topographic contours, were observed in the intensity data as well as in DEM differences Fig.
Unlike real interferometric fringes, the phase of the observed features does not cycle through the full two pi cycle but rather undulates around a mean value. Similarly to contour lines, their frequency correlates with the terrain slope angle: the steeper the terrain, the smaller the distance between them.
In this study the origin of the ochsohypsen was investigated and they were modeled using the real geometry. We show that the ochsohypsen are multipath interference patterns between waves directly travelling to the target area and waves indirectly reaching it via reflection on a flat surface between the radar and the target area. This reflection may happen on either or both travel directions of the wave. This interference of the two wavefronts is similar to the famous double slit experiment.
Constructive and destructive interference of the direct, simple and double reflected indirect waves at the radar generate the observed ochsohypsen. The regular interferometric fringe spacing is given by the same formula with d being the effective perpendicular baseline. Similarly to the initial Davos campaign, a ground based, real aperture, fully polarimetric radar interferometer operating in Ku-band was positioned in a way that it was looking upward to the target area, which was separated from the radar by a flat surface.
The exact date of diagnosis of dementia was recorded in total for The documents and medical records indicated a large heterogeneity in the extent of diagnostic procedures taken for both the initial and differential diagnoses of dementia. In at least one case, the medical specialist documented that the patient himself refused to undergo brain imaging. This implies that not all ESTHER patients whose blood samples were part of our cohort analysis were diagnosed with the same diagnostic standard, which reflects routine clinical practice.
We randomly selected the controls from strata defined by age, sex, educational level as matching factors frequency matching , so that cases and controls were similar with regard to these relevant confounding factors. Measurement of the APOE genetic polymorphism and availability of additional medical data among participants of the ESTHER study also allowed an indirect verification of the correctness of dementia diagnoses.
Likewise, the high baseline prevalence of history of cardiovascular diseases among VD cases The assay was therefore performed in a blinded manner solely by the Bochum group. Only at this point did the Heidelberg group disclosed to the Bochum group the link between ID numbers and dementia status. APOE genotype and epidemiological factors e. The research subjects were thoroughly assessed for their cognitive complaints by physicians with special interest in dementia disorders.
The exclusion criteria were as follows: i cognitive impairment that without doubt could be explained by a condition other than prodromal dementias; ii severe somatic disease; and iii refusing lumbar puncture or neuropsychological investigation. The exclusion criteria were as follows: i presence of significant neurologic or psychiatric disease e. For both diagnostic groups, 40 subjects that fulfilled these criteria were randomly selected from the total sample collective and sent to Bochum.
For plasma collection, blood was drawn into tubes containing EDTA as an anticoagulant. For each plasma sample, a freshly prepared sensor surface was used. Difference absorbance spectra of each preparative step were recorded and served as a qualitative internal control for the success of each step. Before determination of the amide I maximum position, all spectra were baseline corrected and adjusted based on spectral traces of atmospheric water vapour.
Atmospheric water vapour was removed by scaled subtraction of a reference spectrum. Thus, differences between groups were tested for statistical significance by a nonparametric Kruskal—Wallis analysis of variance test. For ROC curve analyses, the threshold was set between 1, Statistical tests, tests for outliers, data preprocessing, receiver operating characteristic curve analysis and data distribution analysis were performed using Matlab A, Matlab A Mathworks and Origin Origin Laboratories.
LP carried out the epidemiological analyses. JG and AN developed the sensor automatisation. JS synthesised reagents for the sensor functionalisation. All authors discussed the results, commented on the draft manuscript and approved the final manuscript. The assay works cost effective, simple and robust with only smallest amounts of blood plasma.
AD is indicated by a frequency shift below the experimentally determined threshold. Moreover, there are indications that the sensor might also differentiate between AD and other dementia forms. This has to be validated in detail in larger studies. The authors acknowledge gratefully most helpful and constructive comments from Dr. Konrad Beyreuther, Dr. Jens Wiltfang, Dr. Christian Hoppe and especially Dr.
David Rumschitzki. National Center for Biotechnology Information , U. Published online Apr 6. Author information Article notes Copyright and License information Disclaimer. Klaus Gerwert, Email: ed. Corresponding author. Published under the terms of the CC BY 4. This article has been cited by other articles in PMC. Associated Data Supplementary Materials. Abstract Alzheimer's disease AD is currently incurable, but there is general agreement that a minimally invasive blood biomarker for screening in preclinical stages would be crucial for future therapy.
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