persistent scatterer interferometric synthetic aperture radar for crustal deformation analysis with application to volcan alcedo galapagos 1 while conventional interferometric synthetic aperture radar insar is a very effective technique for measuring crustal deformation almost any interferogram includes large areas where the signals decorrelate and no measurement is possible persistent scatterer ps insar overcomes the decorrelation problem by identifying resolution elements whose echo is dominated by a single scatterer in a series of interferograms existing ps methods have been very successful in analysis of urban areas where stable angular structures produce efficient reflectors that dominate background scattering however man made structures are absent from most of the earth s surface furthermore existing methods identify ps pixels based on the similarity of their phase history to an assumed model for how deformation varies with time whereas characterizing the temporal pattern of deformation is commonly one of the aims of any deformation study we describe here a method for ps analysis stamps that uses spatial correlation of interferogram phase to find pixels with low phase variance in all terrains with or without buildings prior knowledge of temporal variations in the deformation rate is not required for their identification we apply stamps to volcan alcedo where conventional insar fails because of dense vegetation on the upper volcano flanks that causes most pixels to decorrelate with time we detect two sources of deformation the first we model as a contracting pipe like body which we interpret to be a crystallizing magma chamber the second is downward and lateral motion on the inner slopes of the caldera which we interpret as landsliding

velocity field of the la clapiere landslide measured by the correlation of aerial and quickbird satellite images 1 two displacement maps of the la clapiere landslide france have been derived over two periods of 4 years 1995 1999 and 1999 2003 by correlation of aerial photographs and a quickbird satellite image the movement of the landslide ranges from 2 5 m to 20 m per year those values have been validated over 13 points monitored by conventional tacheometric measurements three areas with significant differences in velocity field have been mapped limits of those areas are in good agreement with in situ observations velocity maps show the low long term temporal variability of the landslide movement and its spatial variability the optical correlation method using images derived from various sensors airborne and spatial is a promising technique for improving the spatial resolution of velocity field observation of landslides over several years

interferogram formation in the presence of complex and large deformation 1 sierra negra volcano in isabela island galapagos erupted from october 22 to october 30 in 2005 during the 8 days of eruption the center of sierra negra s caldera subsided about 5 4 meters three hours prior to the onset of the eruption an earthquake mw 5 4 occurred near the caldera because of the large and complex phase gradient due to the huge subsidence and the earthquake it is difficult to form an interferogram inside the caldera that spans the eruption the deformation is so large and spatially variable that the approximations used in existing insar software roi roi pac doris gamma cannot properly coregister sar image pairs spanning the eruption we have developed here a two step algorithm that can form intra caldera interferograms from these data the first step involves a rubber sheeting sar image coregistration in the second step we use range offset estimates to mitigate the steep phase gradient using this new algorithm we retrieve an interferogram with the best coverage to date inside the caldera of sierra negra

landslide hazard assessment in the three gorges area of the yangtze river using aster imagery zigui badong this paper reports a regional assessment of landslide hazard in the three gorges area china based on terra 1 satellite advanced spaceborne thermal emission radiometer aster imagery data including a stereo image derived digital elevation model dem and multi spectral reflective and thermal imagery in combination with limited field investigation the three gorges dam and reservoir project has gained international attention not only for its great potential for hydro electrical power generation and flood control but also for its potentially harmful effects on the environment and socio economy the most significant and widespread natural hazard in the region is slope instability a simple multi variable elimination and characterisation model employing geometric mean and boolean decision rules has been applied to a multi criterion image dataset to categorise the area into a series of potential landslide hazard levels which are presented in map form the results presented here show high levels of hazard in and around all the main inhabited areas along the river limited fieldwork has been conducted to provide reliable ground control and the results of this paper show good correlation with this field evidence

detecting and monitoring of landslides using persistent scattering synthetic aperture radar interferometry persistent scatterer synthetic aperture radar interferometry psinsar is an applied time series technique to overcome limitations of insar temporal and geometrical decorrelation and atmospheric delay anomalies for monitoring of ground surface deformations this method only monitors displacements on pixels with nearly constant temporal backscattering characteristics in this study datasets of ascending alos palsar l band images recorded from 2006 to 2010 and descending envisat asar c band images acquisitioned between 2003 and 2010 were processed to detect and monitor the landslide occurred in the noghol area iran application of the psinsar technique on both palsar and asar images has significantly improved monitoring of the noghol landslide however the determination of vertical displacement of the landslide by the asar images processing is more correct compared to results of the palsar processing due to the descending orbital motion of asar the asar images also overwhelm palsar images for determination of the landslide extent because of detection of more persistent scatterer points the landslide displacement and aspect obtained by the global navigation satellite system gnss and psinsar techniques are in agreement about 1 2 1 5 m westward in the period of 2003 2010 particularly processing results of the asar images are more similar to the gnss measurements furthermore assessment of the landslide type mechanism and its displacement direction were possible by integration of the palsar and asar radar images with ascending and descending orbital motions respectively

application of image cross correlation to the measurement of glacier velocity using satellite image data abstract image to image cross correlation software is applied to pairs of digital satellite images to map the velocity field of moving ice this technique uses small scale glacial surface features such as crevasse scars and snow dunes as markers on the surface of the moving ice displacements of the surface features are mapped by selecting small image areas centered on distinct features or by dividing a large area of densely featured glacial surface into a grid of areas and searching a subsequent image for matching areas using a cross correlation algorithm interpolation of the peak correlation values allows the displacements to be measured to subpixel accuracy resulting in very precise velocity measurements cross correlation is also applied to provide image coregistration in areas devoid of bedrock exposures in such areas subtle large scale topographic undulations in the ice surface related to underlying bedrock structure may be correlated by using large image areas and low pass filtered images both types of applications are demonstrated using ice stream d and ice stream e in west antarctica as test areas a high resolution map of the velocity field of the central portion of ice stream e generated by the displacement measuring technique is presented the use of cross correlation software is a significant improvement over previous manually based photogrammetric methods for velocity measurement and is far more cost effective than in situ methods in remote polar areas

a new functional model for determining minimum and maximum detectable deformation gradient resolved by satellite radar interferometry in this paper a functional model for determining the minimum and maximum detectable deformation gradient in terms of coherence for synthetic aperture radar sar sensors is presented the model is developed based on a new methodology that incorporates both real and simulated data sets of representative surface deformation models have been simulated and the associated phase from these models introduced into real sar data acquired by european remote sensing 1 and 2 satellites subsequently interferograms were derived and surface deformation was estimated a number of cases of surface deformation with varying magnitudes and spatial extent have been simulated in each case the resultant surface deformation has been compared with the true surface deformation as defined by the deformation model based on these comparisons a set of observations that lead to a new functional model has been established finally the proposed model has been validated against external datasets and proven viable although the major weakness of the model is its reliance on visual interpretation of interferograms this model can serve as a decision support tool to determine whether or not to apply satellite radar interferometry to study a given surface deformation

three dimensional time varying large surface displacements in coal exploiting areas revealed through integration of sar pixel offset measurements and mining subsidence model abstract underground mining activities usually induce large surface displacements thus causing serious safety hazards and potential ecological damage the capability of conventional interferometric synthetic aperture radar insar to monitor tectonic movements volcanic eruptions and city subsidence has been fully demonstrated but its application to mining subsidence is limited because of the failure caused by localized surface displacements with strong spatial gradients in this paper a new method is presented to utilize sar pixel offset tracking ot with a single pair of sar images to resolve three dimensional 3d large surface displacements caused by underground coal mining coal mining subsidence theory is utilised to analytically separate the vertical and horizontal components this method is applied to the daliuta coal mining area in shaanxi province china where a dense gps network is available results show the rms differences of ot derived displacements against gps in both horizontal and vertical directions are in the sub centimeter level in addition a prediction of mining induced ground movements is performed with the support vector regression algorithm and rms differences of 12 4 13 1 and 14 4 cm are observed compared to gps in the vertical easting and northing directions respectively the framework demonstrated in this paper is not only able to derive the evolution of the 3d large surface displacements with multi temporal sar images in a single geometry but also has a potential for short term predication which can provide early warnings and promote strategic decision making for engineering management in the process of coal mining

interferometric synthetic aperture radar insar atmospheric correction gps moderate resolution imaging spectroradiometer modis and insar integration atmospheric effects represent one of the major limitations of repeat pass interferometric synthetic aperture radar insar in this paper gps and moderate resolution imaging spectroradiometer modis data were integrated to provide regional water vapor fields with a spatial resolution of 1 km 1 km and a water vapor correction model based on the resultant water vapor fields was successfully incorporated into the jet propulsion laboratory california institute of technology roi pac software the advantage of this integration approach is that only one continuous gps station is required within a 2030 km 1354 km modis scene application to ers 2 repeat pass data over the los angeles southern california integrated gps network scign area shows that this integration approach not only helps discriminate geophysical signals from atmospheric artifacts but also reduces water vapor effects significantly which is of great interest to a wide community of geophysicists

measuring ground displacements from sar amplitude images application to the landers earthquake ers sar amplitude images are utilized to map ground displacements from a sub pixel correlation method it yields a ground two dimensional displacement field with independent measurements about every 128m in azimuth and 250m in range the accuracy depends on the characteristics of the images for the landers test case the 1 uncertainty is 0 8m in range and 0 4m in azimuth we show that this measurement provides a map of major surface fault ruptures accurate to better than 1km and information on coseismic deformation comparable to the 92 gps measurements available although less accurate this technique is more robust than sar interferometry and provides complementary information since interferograms are only sensitive to the displacement in range

surface displacements and source parameters of the 2003 bam iran earthquake from envisat advanced synthetic aperture radar imagery 1 the mw 6 6 26 december 2003 bam iran earthquake was one of the first earthquakes for which envisat advanced synthetic aperture radar asar data were available using interferograms and azimuth offsets from ascending and descending tracks we construct a three dimensional displacement field of the deformation due to the earthquake elastic dislocation modeling shows that the observed deformation pattern cannot be explained by slip on a single planar fault which significantly underestimates eastward and upward motions se of bam we find that the deformation pattern observed can be best explained by slip on two subparallel faults eighty five percent of moment release occurred on a previously unknown strike slip fault running into the center of bam with peak slip of over 2 m occurring at a depth of 5 km the remainder occurred as a combination of strike slip and thrusting motion on a southward extension of the previously mapped bam fault 5 km to the east

smithian shoreline migrations and depositional settings in timpoweap canyon early triassic utah usa in timpoweap canyon near hurricane utah usa spectacular outcrop conditions of early triassic rocks document the geometric relationships between a massive smithian fenestral microbial unit and underlying lateral and overlying sedimentary units this allows us to reconstruct the evolution of depositional environments and high frequency relative sea level fluctuations in the studied area depositional environments evolved from a coastal plain with continental deposits to peritidal settings with fenestral microbial limestones which are overlain by intertidal to shallow subtidal marine bioclastic limestones this transgressive trend of a large scale depositional sequencemarks a long term sea level rise that is identified worldwide after the permian triassic boundary the fenestral microbial sediments were deposited at the transition between continental settings with terrigenous deposits and shallow subtidal marine environments with bioturbated and bioclastic limestones such a lateral zonation questions the interpretation of microbial deposits as anachronistic and disaster facies in the western usa basin the depositional setting may have triggered the distribution of microbial deposits and contemporaneous marine biota the fenestral microbial unit is truncated by an erosional surface reflecting a drop in relative sea level at the scale of a medium depositional sequence the local inherited topography allowed the recording of small scale sequences characterized by clinoforms and short distance lateral facies changes stratal stacking pattern and surface geometries allow the reconstruction of relative sea level fluctuations and tracking of shoreline migrations the stacking pattern of these small scale sequences and the amplitude of corresponding high frequency sea level fluctuations are consistent with climatic control large andmedium scale sequences suggest a regional tectonic control

atmospheric effects in interferometric synthetic aperture radar surface deformation and topographic maps interferogram images derived from repeat pass spaceborne synthetic aperture radar systems exhibit artifacts due to the time and space variations of atmospheric water vapor other tropospheric variations such as pressure and temperature also induce distortions but the effects are smaller in magnitude and more evenly distributed throughout the interferogram than the wet troposphere term spatial and temporal changes of 20 in relative humidity lead to 10 cm errors in deformation products and perhaps 100 m of error in derived topographic maps for those pass pairs with unfavorable baseline geometries in wet regions such as hawaii these are by far the dominant errors in the spaceborne imaging radar c and x band synthetic aperature radar sir c x sar interferometric products the unknown time delay from tropospheric distortion is independent of frequency and thus multiwavelength measurements such as those commonly used to correct radar altimeter and global positioning system gps ionospheric biases cannot be used to rectify the error in the topographic case the errors may be mitigated by choosing interferometric pairs with relatively long baselines as the error amplitude is inversely proportional to the perpendicular component of the interferometer baseline for the sir c x sar hawaii data we found that the best longest baseline pair produced a map supporting 100 m contouring whereas the poorest baseline choice yielded an extremely noisy topographic map even at this coarse contour interval in the case of deformation map errors the result is either independent of baseline parameters or else very nearly so here the only solution is averaging of independent interferograms so in order to create accurate deformation products in wet regions many multiple passes may be required rules for designing optimal data acquisition and processing sequences for interferometric analyses in nondesert parts of the world are 1 to use the longest radar wavelengths possible within ionospheric scintillation and faraday rotation limits 2 for topography maximize interferometer baseline within decorrelation limits and 3 for surface deformation use multiple observations and average the derived products following the above recipe yields accuracies of 10 m for digital elevation models and 1 cm for deformation maps even in very wet regions such as hawaii

analysis of the deep seated gravitational slope deformations over mt frascare central italy with geomorphological assessment and dinsar approaches abstract a quantitative and innovative dgsd deep gravitational slope deformation assessment method that used integrated remote sensing was tested in the central apennine mountain range italy the movement rate was calculated for selected test areas using the differential sar interferometry small baseline subset sbas technique the selected test areas were previously identified by interpreting both aerial photos and using 32 ers radar images taken between 1993 and 2000 more than 15 cm of cumulative surface displacement occurred across the podalla dgsd along the satellite line of sight los moreover the displacement time series showed non linear deformation rates which included periods of accelerated movement correlated with strong rainfall the high estimated podalla dgsd activity indicates that this type of study should be conducted to monitor the evolution of this phenomenon in addition the dinsar movement rate can be used to improve mapping and identify dgsds in specific landscapes

displacement field and slip distribution of the 2005 kashmir earthquake from sar imagery 1 the 8th october 2005 kashmir earthquake mw 7 6 involved primarily thrust motion on a ne dipping fault sub pixel correlation of envisat sar images gives the location of the 80 km long fault trace within 300 800 m and a 3d surface displacement field with a sub metric accuracy covering the whole epicentral area the slip distribution inverted using elastic dislocation models indicates that slip occurs mainly in the upper 10 km between the cities of muzaffarabad and balakot the rupture reached the surface in several places in the hanging wall horizontal motions show rotation from pure thrust to oblique right lateral motion that are not observed in the footwall a segmentation of the fault near muzaffarabad is also suggested north of the city of balakot slip decreases dramatically but a diffuse zone of mainly vertical surface displacements which could be post seismic exists further north where most of the aftershocks occur aligned along the nw se indus kohistan seismic zone

a radar backscatter model for discontinuous coniferous forests a radar backscattering model for low to medium density woodland in which each tree is treated as an individual backscatterer is described a forest stand viewed by radar is then an assemblage of scatterers standing on a background in a certain spatial pattern the backscattering components arising from the various intersections of radar beams with the forest stand are calculated separately and their stokes matrices are then added together to achieve the stokes matrix for total backscattering probabilities of radar beams intersecting tree crowns are introduced into the model

radar interferometry and its application to changes in the earth s surface geophysical applications of radar interferometry to measure changes in the earth s surface have exploded in the early 1990s this new geodetic technique calculates the interference pattern caused by the difference in phase between two images acquired by a spaceborne synthetic aperture radar at two distinct times the resulting interferogram is a contour map of the change in distance between the ground and the radar instrument these maps provide an unsurpassed spatial sampling density 100 pixels km 2 a competitive precision 1 cm and a useful observation cadence 1 pass month 1 they record movements in the crust perturbations in the atmosphere dielectric modifications in the soil and relief in the topography they are also sensitive to technical effects such as relative variations in the radar s trajectory or variations in its frequency standard we describe how all these phenomena contribute to an interferogram then a practical summary explains the techniques for calculating and manipulating interferograms from various radar instruments including the four satellites currently in orbit ers 1 ers 2 jers 1 and radarsat the next chapter suggests some guidelines for interpreting an interferogram as a geophysical measurement respecting the limits of the technique assessing its uncertainty recognizing artifacts and discriminating different types of signal we then review the geophysical applications published to date most of which study deformation related to earthquakes volcanoes and glaciers using ers 1 data we also show examples of monitoring natural hazards and environmental alterations related to landslides subsidence and agriculture in addition we consider subtler geophysical signals such as postseismic relaxation tidal loading of coastal areas and interseismic strain accumulation we conclude with our perspectives on the future of radar interferometry the objective of the review is for the reader to develop the physical understanding necessary to calculate an interferogram and the geophysical intuition necessary to interpret it

the 2010 mw 6 8 yushu qinghai china earthquake constraints provided by insar and body wave seismology 1 by combining observations from satellite radar body wave seismology and optical imagery we have determined the fault segmentation and sequence of ruptures for the 2010 mw 6 8 yushu china earthquake we have mapped the fault trace using displacements from sar image matching interferometric phase and coherence and 2 5 m spot 5 satellite images modeling the event as an elastic dislocation with three segments fitted to the fault trace suggests that the southeast and northwest segments are near vertical with the central segment dipping 70 to the southwest slip occurs mainly in the upper 10 km with a maximum slip of 1 5 m at a depth of 4 km on the southeastern segment the maximum slip in the top 1 km i e near surface is up to 1 2 m and inferred locations of significant surface rupture are consistent with displacements from sar image matching and field observations the radar interferograms show rupture over a distance of almost 80 km much larger than initial seismological and field estimates of the length of the fault part of this difference can be attributed to slip on the northwestern segment of the fault being due to an mw 6 1 aftershock two hours after the main event the remaining difference can be explained by a non uniform slip distribution with much of the moment release occurring at depths of less than 10 km the rupture on the central and southeastern segments of the fault in the main shock propagated at a speed of 2 5 km s southeastward toward the town of yushu located at the end of this segment accounting for the considerable building damage strain accumulation since the last earthquake on the fault segment beyond yushu is equivalent to an mw 6 5 earthquake

interferometric synthetic aperture radar atmospheric correction gps topography dependent turbulence model 1 over the last two decades repeat pass interferometric synthetic aperture radar insar has been widely used as a geodetic technique for measuring the earth s surface including topography and deformation like other astronomical and space geodetic techniques repeat pass insar is limited by the variable spatial and temporal distribution of atmospheric water vapor in this paper a topography dependent turbulence model gttm for short has been developed using gps data only to produce zenith path delay difference maps for insar atmospheric correction application of the gttm model to ers tandem data over the los angeles southern california integrated gps network area has shown that use of the gttm can reduce water vapor effects on interferograms from 10 mm down to 5 mm which is of great interest to a wide community of geophysicists the principal finding of this paper is that interpolation methods should be applied to zenith total delay ztd differences from different times instead of ztd values themselves for the purpose of insar atmospheric correction this is crucial to reduce if not completely remove topographic effects on ztd values

an insight into the surface velocity of inylchek glacier and its effect on lake merzbacher during 2006 2016 with landsat time series imagery mountain glacier is one of the extremely sensitive indicators for climate change and its surface motion distribution and corresponding variation are valuable information for understanding ice mass exchange and glacier dynamics this paper presents the long term ice velocity distributions of inylchek glacier in the tianshan region by pixel tracking algorithm with time series landsat imagery acquired during 2006 2016 then the monitored ice motion fields of inylchek glacier were carefully analyzed and revealed a generally similar spatial distribution characteristic most of the ice of the north inylchek glacier remains in a stagnant state except for the upstream part but a relatively high velocity of 20 40 cm day with an rmse of 3 cm day was observed on most part of the south inylchek glacier except for the slow moving glacier terminus we also state the glacier dynamics around lake merzbacher and their possible effect on its glacier lake outburst flood glof risk besides the surface velocity distribution on south inylchek glacier surface during the ablation period from 2014 to 2016 was also established and also compared with annual velocity the corresponding difference yields that there is a positive relation between ice motion and temperature variation therefore the time series ice surface motion yielded by the landsat imagery thus could provide us an efficient and low cost way to analyze the current state and changes in glaciers thanks to the continuous and regular spaceborne observations provided by the landsat satellites

fault slip distribution of the 1999 mw 7 1 hector mine california earthquake estimated from satellite radar and gps measurements we use a combination of satellite radar and gps data to estimate the slip distribution of the 1999 m w 7 1 hector mine earthquake a right lateral strikeslip earthquake that occurred on a northwest southeast striking fault in the southern california mojave desert the data include synthetic aperture radar interferograms insar from both ascending and descending orbits radar amplitude image offset fields sario for both ascending and descending azimuth directions and campaign gps observations from 55 stations provided by agnew et al 2002 we model the fault with nine segments derived from the field mapped fault rupture the sario data and aftershock locations we first estimate the dip of each fault segment as well as a single constant strike slip component across each segment resulting in an average dip of 83 to the northeast and slip of up to 5 6 m then we fix the optimal fault segment dip discretize the fault segments into 1 5 km 1 5 km patches and solve for the variable slip distribution using a nonnegative least squares method that includes an appropriate degree of smoothing our preferred solution has both right lateral strike slip and reverse faulting the estimated geodetic moment is 5 93 10 19 n m m w 7 1 similar to seismological estimates indicating that there are insignificant interseismic and postseismic deformation signals in the data we find strike slip displacements of up to 6 0 m and reverse faulting of up to 1 6 m with the maximum slip located just northwest of the epicenter most of the slip is concentrated northwest and south of the epicenter little slip is found on the northeastern branch of the fault the sario data and our modeling indicate that the amount and extent of surface fault rupture were underestimated in the field

monitoring activity at the daguangbao mega landslide china using sentinel 1 tops time series interferometry abstract the daguangbao mega landslide china induced by the 2008 wenchuan earthquake m w 7 9 with an area of approximately 8 km 2 is one of the largest landslides in the world experts predicted that the potential risk and instability of the landslide might remain for many decades or even longer monitoring the activity of such a large landslide is hence critical terrain observation by progressive scans tops mode from the sentinel 1 satellite provides us with up to date high quality synthetic aperture radar sar images over a wide ground coverage 250 250 km enabling full exploitation of various insar applications however the tops mode introduces azimuth dependent doppler variations to radar signals which requires an additional processing step especially for sar interferometry sentinel 1 tops data have been widely applied to earthquakes but the performance of tops data based time series analysis requires further exploitation in this study sentinel 1 tops data were employed to investigate landslide post seismic activities for the first time to deal with the azimuth dependent doppler variations a processing chain of tops time series interferometry approach was developed since the daguangbao landslide is as a result of the collapse of a whole mountain caused by the 2008 mw 7 9 wenchuan earthquake the existing digital elevation models dems e g srtm and aster exhibit height differences of up to approximately 500 m tandem x images acquired after the earthquake were used to generate a high resolution post seismic dem the high gradient topographic errors of the srtm dem i e the differences between the pre seismic srtm and the actual post seismic elevation together with low coherence in mountainous areas make it difficult to derive a precise dem using the traditional insar processing procedure a re flattening iterative method was hence developed to generate a precise tandem x dem in this study the volume of the coseismic daguangbao landslide was estimated to be of 1 189 0 110 10 9 m 3 by comparing the postseismic tandem x dem with the preseismic srtm dem which is consistent with the engineering geological survey result the time series results from sentinel 1 show that some sectors of the daguangbao landslide are still active and displaying four sliding zones and exhibiting a maximum displacement rate of 8 cm year even eight years after the wenchuan earthquake the good performance of tops in this time series analysis indicates that up to date high quality tops data with spatiotemporal baselines offer significant potential in terms of future insar applications

a method for measuring 3 d surface deformations with insar based on strain model and variance component estimation interferometric synthetic aperture radar insar technique is a proven technique for measuring 3 d surface deformations by combining insar measurements from different techniques i e differential insar multiaperture insar and pixel offset tracking and different tracks i e ascending and descending on a pixel by pixel basis however it is difficult to obtain the exact a priori variances or weights for such different kinds of insar measurements resulting in inaccurate estimations of 3 d deformations this paper proposes a method to retrieve 3 d deformations with insar by integrating the strain model and variance component estimation algorithm which can exploit the spatial correlation of the adjacent points deformations and produce accurate weights for multiple insar measurements the proposed method is assessed with both simulated and real data sets the results have shown that the proposed method can accurately measure 3 d surface deformations associated with geohazards and even those occurring in a transient or short term period e g earthquake and volcanic eruption in the case study of the 2007 eruption of kilauea volcano hawai i improvements of 51 2 22 4 and 18 5 have been achieved for the derived east north and up displacements respectively with respect to those derived from the classical weighted least squares method

a survey of temporal decorrelation from spaceborne l band repeat pass insar abstract in this paper we quantify the effects of temporal decorrelation in repeat pass synthetic aperture radar interferometry insar temporal decorrelation causes significant uncertainties in vegetation parameter estimates obtained using various insar techniques which are desired on a global scale because of its stochastic nature temporal decorrelation is hard to model and isolate in this paper we analyze temporal decorrelation statistically as observed in a large swath of sir c l band insar data collected over the eastern united states with a repeat pass duration of one day in october 1994 and a near zero perpendicular baseline the very small baseline for this particular pair makes the effect of volumetric scattering on correlation magnitude statistics nearly imperceptible allowing for a quantitative analysis of temporal effects alone the swath analyzed in this paper spans more than a million hectares of terrain comprised primarily of deciduous and evergreen forests agricultural land water and urban areas the relationships of these different land cover types phenology and weather conditions i e precipitation and wind on the measures of interferometric correlation is analyzed in what amounts to be the most geographically extensive analysis of this phenomenon to date

testing the potential of sentinel 1a tops interferometry for the detection and monitoring of landslides at local scale veneto region italy the recent sentinel 1 mission started by the european space agency in april 2014 provides the scientific community with new capabilities for the monitoring of the earth surface in particular the terrain observation by progressive scans imaging technique used in the interferometric wide swath acquisition mode permits to acquire data over very wide areas 250 km of swath extension at 20 m spatial resolution with 12 day revisit time making it suitable for ground displacement monitoring applications with more than 1 year of synthetic aperture radar images available it is now possible to carry out monitoring activities of slow moving phenomena such as landslides at both regional and local scales in this work the potential of sentinel 1a for the monitoring of shallow from 2 to 6 m of depth landslides occurring in the north eastern italian pre alps was tested two stacks of sentinel 1a scenes acquired in both ascending and descending orbits were processed using the permanent scatterer interferometry psi technique the results analysed in terms of ps density and quality were compared with the ers 1 2 and envisat psi database available from the italian national cartographic portal to assess the capabilities of sentinel 1a in detecting and monitoring landslides in respect to the previous satellite missions the results of this work show the great potential of sentinel 1a in the continuous monitoring of landslide prone territories even at local scale the achievable results can provide information that is useful to delineate the spatial and temporal evolution of landslides and precisely assess their rates of deformation

a spatially varying scaling method for insar tropospheric corrections using a high resolution weather model variation in tropospheric delay is a major limiting factor on the accuracy of interferometric synthetic aperture radar insar measurements this is particularly the case when deformation and topography are correlated to address limitations of previous insar tropospheric correction methods here we present a new approach that combines the use of both external weather model data and the interferometric phase we assume that vertical refractivity profiles calculated from a high resolution weather model data can generally describe the form of the relationship between tropospheric delay and height but that the magnitude can be incorrect we estimate a magnitude correction by scaling the original delays to best match the interferometric phase we validated our new method using simulated data and demonstrate that both coseismic and interseismic signals can be separated from strong tropospheric delays we also applied our algorithm to the central portion of the altyn tagh fault in northern tibet where deformation correlates strongly with topographic relief of 6 000 m and show that the derived velocity field is more internally consistent and agrees better with independent global positioning system measurements

use of differential sar interferometry in monitoring and modelling large slope instability at maratea basilicata italy abstract differential synthetic aperture radar sar interferometry diffsar allows in principle to measure very small movements of the ground and to cover in continuity large areas so that it can be considered as a potentially ideal tool to investigate landslides and other slope instability in this paper we explore the use of this technique to improve our knowledge of the slope instability of a well investigated area the maratea valley affected by continuous slow movements producing an impressive sackung type phenomenon which poses several unanswered questions in particular by using this technique we analyse the time evolution of ground movements from 1997 to 2000 the slope movements during this same time interval have also been monitored in the past by using other techniques such as electronic distance meter edm and gps measurements gps and diffsar results are here compared in our implementation of the diffsar technique the problem of decorrelation noise is faced by using a phase unwrapping approach that allows to process sparse data and the impact of atmospheric artefacts is reduced by performing a temporal analysis of the deformations observed in successive interferograms in this study we also show that it is possible to perform a temporal analysis of continuous slow landslide movements by using a limited number of ers sar data sets and low precision topographic information all the acquired data edm gps and diffsar are consistent and allow a kinematic model of instability within the investigated time interval to be proposed a map of slopes subject to different velocities of vertical displacements was delineated modifying previous knowledge within the valley progressive and almost linear displacements over time were confirmed

the complete 3 d surface displacement field in the epicentral area of the 1999 mw7 1 hector mine earthquake california from space geodetic observations we use interferometric synthetic aperture radar insar data to derive continuous maps for three orthogonal components of the co seismic surface displacement field due to the 1999 m w7 1 hector mine earthquake in southern california vertical and horizontal displacements are both predominantly antisymmetric with respect to the fault plane consistent with predictions of linear elastic models of deformation for a strike slip fault some deviations from symmetry apparent in the surface displacement data may result from complexity in the fault geometry

correction for interferometric synthetic aperture radar atmospheric phase artifacts using time series of zenith wet delay observations from a gps network 1 radar interferograms provide precise millimeter level measurements of crustal deformation at fine resolution over wide areas the dominant error source in many interferograms results from spatial heterogeneity of the wet component of atmospheric refractivity resulting in excess path length of the radar signal propagating through the neutral atmosphere in this report we introduce a method to compensate for atmospheric phase artifacts in a radar interferogram using spatially interpolated zenith wet delay zwd data obtained from a network of global positioning system gps receivers in the region imaged by the radar our method based on taylor s frozen flow hypothesis uses gps data recorded prior to and after the individual radar acquisition times to infer denser spatial networks of control points for interpolation than is suggested by the sparse and irregular spatial distribution of gps receivers we test this approach by correcting phase fluctuations observed in a radar interferogram over an area covered by the southern california integrated gps network stations using maps of atmospheric delay interpolated from the denser network of gps zwd measurements generated by our method we find that the largest improvement results from removing an altitude dependent model derived from the gps data the uncorrected interferogram in our example has an rms fluctuation of 16 1 mm which falls to 8 6 mm after the altitude correction a map derived from zwd measurements recorded only at the instances of radar acquisition reduced overall fluctuations in the data from 8 6 to 8 1 mm rms while using the inferred denser network reduces the error further to 7 5 mm rms most of this residual variation is due to decorrelation of the signal and does not result from atmospheric propagation however after smoothing to remove decorrelation noise the residual drops from 4 7 to 3 9 mm gps stations only and then to 2 7 mm rms when the denser network algorithm is used

surface displacements and surface age estimates for creeping slope landforms in northern and eastern iceland using digital photogrammetry abstract in this study three areas of different active coarse debris slope processes are investigated in northern and eastern iceland surface displacement of some glacier derived rock glaciers and a debris covered glacier in the holar area a moving debris accumulation close to siglufjor ur and a debris layer in sey isfjor ur are measured the displacement fields are obtained by cross correlation matching of multi temporal orthophotos orthophotos are generated using a z i imaging digital photogrammetric workstation and various series of air photos from 1964 to 1994 cross correlation matching is done with the cias software the results are analyzed and used for rough surface age estimates in addition type and cause of movement are discussed the velocity of the debris covered glacier and the rock glaciers in the holar area averages from 0 14 to 0 67 m a 1 the debris accumulation at almenningsnof close to siglufjor ur shows an average displacement of 0 19 m a 1 with a maximum value of 0 84 m a 1 the displacements at almenningsnof agree well with displacements surveyed by gps by the icelandic road authorities the measured velocities in sey isfjor ur although using air photos taken 30 years apart turned out not to be significant but the homogenous direction of the displacement vectors suggests that the debris is currently creeping based on the surface age results all the landforms in holar are suggested to have developed during the late holocene cooling period with ages from around 1500 and 3000 to around 5000 years for the different landforms these surface age estimates coincide with data from moraine datings nearby and holocene climatic development in the north atlantic region

dynamics of slow moving landslides from permanent scatterer analysis high resolution interferometric synthetic aperture radar insar permanent scatterer data allow us to resolve the rates and variations in the rates of slow moving landslides satellite to ground distances range changes on landslides increase at rates of 5 to 7 millimeters per year indicating average downslope sliding velocities from 27 to 38 millimeters per year time series analysis shows that displacement occurs mainly during the high precipitation season during the 1997 1998 el nino event rates of range change increased to as much as 11 millimeters per year the observed nonlinear relationship of creep and precipitation rates suggests that increased pore fluid pressures within the shallow subsurface may initiate and accelerate these features changes in the slope of a hill resulting from increases in the pore pressure and lithostatic stress gradients may then lead to landslides

glacier surface motion pattern in the eastern part of west kunlun shan estimation using pixel tracking with palsar imagery mountain glacier is considered as one of the most sensitive natural indicators of climate change glacier surface motion distribution in west kunlun shan wks has been attracting considerable attention and represents a fundamental glacier parameter for better understanding glacier dynamics ice mass balance and even for the climate change this paper would present the accurate ice motion observation of mountain glacier in eastern part of wks by the refined pixel tracking method with phased array type l band synthetic aperture radar images acquired on december 13 2008 and january 28 2009 the standard deviation values in nonglacial area before after topographic effect compensation are 0 61 and 0 43 m respectively during 46 day temporal interval in addition the terrain almost is a determining factor of ice velocity distribution in study area because the elevation of topography is generally shown to be positive correlated with glacier surface velocity along the central line furthermore with estimated detailed glacier surface movement distribution pattern we found that the continental glaciers were actively moving with spatially variable ice motion while the icecaps maintain the stable status without apparent motion on most part of surface therefore the refined sar based pixel tracking method including topographic effect compensation operation provides a useful and robust tool to map and measure the glacier motion in mountain area with complex terrain

tributary junction fans of china s yangtze three gorges valley morphological implications abstract the tributary junctions to main rivers within incised canyons reflect the relationships between stream power and sediment fed to the main river by tributary tributary junctions within the three gorges valley of the yangtze river china were classified into 7 types on the basis of the presence or absence of tributary junction fans and the size and style of the fans three reaches totaling 180 km in length were mapped in the field and for a sample of 120 tributary junctions morphometric properties of the feeder catchments were derived small steep tributaries do not generate tributary junction fans nor do the largest tributaries for intermediate sized tributary catchments of approximately 1 30 km2 threshold conditions can be identified between the relatively steep more deeply dissected catchments mean basin slope approximately 0 1 relief range approximately 250 800 m that generate large tributary junction fans and less steep less deeply dissected catchments mean basin slope

deformation time series generation in areas characterized by large displacement dynamics the sar amplitude pixel offset sbas technique we exploit the amplitude information of a sequence of synthetic aperture radar sar images acquired at different times in order to generate displacement time series in areas characterized by large and or rapid deformation the size of which is on the order of the image s pixel dimensions we follow the same rationale of the small baseline subset sbas differential sar interferometry dinsar approach by coupling the available sar images into pairs characterized by a small separation between the acquisition orbits we exploit the amplitudes of the selected image pairs in order to calculate the relative across track range and along track azimuth pixel offsets po finally we apply the sbas inversion strategy to retrieve the range and azimuth displacement time series this approach referred to as pixel offset po sbas technique has been applied to a set of 25 envisat sar observations of the sierra negra caldera galapagos islands spanning the 2003 2007 time interval the retrieved deformation time series show the capability of the technique to detect and measure the large displacements affecting the inner part of the caldera that in correspondence to the october 2005 eruption reached several meters moreover by comparing the po sbas results to continuous gps measurements we estimate that the accuracy of the po sbas time series is on the order of 1 30th of a pixel for both range and azimuth directions

investigating landslides with space borne synthetic aperture radar sar interferometry abstract this paper is addressed to readers without advanced knowledge of remote sensing it illustrates some current and potential uses of satellite synthetic aperture radar interferometry insar for landslide assessment data acquired by sar systems can provide 3d terrain models and be used to assist in regional scale investigations e g aimed at evaluation of susceptibility of slopes to failure under favourable environmental conditions the innovative permanent scatterers ps technique which overcomes several limitations of conventional sar differential interferometry dinsar applications in landslide studies is suitable for monitoring slope deformations with millimetric precision the ps technique combines the wide area coverage typical of satellite imagery with the capability of providing displacement data relative to individual image pixels with the currently available radar satellites however only very slow ground surface displacements can be reliably detected and measured the presented case study of a landslide from the liechtenstein alps indicates that the most attractive and reliable contribution provided by this remote sensing technique lies in the possibility of i wide area qualitative distinction between stable and unstable areas and ii qualitative relative hazard zonation of large slow landslides based on the identification of segments characterised by different movement rates since only the radar line of sight projection of the displacements can be detected a quantitative exploitation of the ps data is possible only where sufficient ground truth is available in site specific or single landslide investigations the ps data can represent a very useful complementary data source with respect to the information acquired through ground based observations and in situ surveying however the difficulties associated with the feasibility assessments of the applicability of sar data to local scale problems as well as with the interpretation of ps results require a close collaboration between landslide experts and specialists in advanced processing of radar satellite data the interpretation of the exact geotechnical significance of small radar sensed ground surface deformations is challenging especially where ground truth is lacking although any ground deformation is potentially of interest to an engineering geologist detection of movements in both vertical and horizontal directions is needed in the case of landslides to evaluate slope failure mechanisms with their high radar viewing angles however the current space borne systems can detect only a fraction of the horizontal component of movement it is expected that the upcoming sar dedicated missions with new sensors and different acquisition geometries combined with the rapid developments in the field of advanced radar data processing will allow a full 3d reconstruction of deformation data and help to further reduce the current limitations of the ps and similar dinsar approaches

monitoring very slow slope movements by means of sar interferometry a case study from a mass waste above a reservoir in the otztal alps austria the application of radar interferometry to detect slope movements on the order of millimeters to centimeters per year is demonstrated the deformation field of a slope above a hydropower reservoir in the austrian alps was derived from sar interferometric pairs of the satellites ers 1 and ers 2 acquired between july 1992 and august 1998 above the treeline it was possible to map the motion from interferograms covering time spans up to three years whereas ground based geodetic measurements focussed on the movements of the lower slope section the interferometric analysis shows that the mass wasting processes affect the entire slope of 1000 m vertical extent significant interannual differences of the displacement rates became apparent which were found to be related to the pattern of summer rainfall

radar interferogram filtering for geophysical applications the use of sar interferometry is often impeded by decorrelation from thermal noise temporal change and baseline geometry power spectra of interferograms are typically the sum of a narrow band component combined with broad band noise we describe a new adaptive filtering algorithm that dramatically lowers phase noise improving both measurement accuracy and phase unwrapping while demonstrating graceful degradation in regions of pure noise the performance of the filter is demonstrated with sar data from the ers satellites over the jakobshavns glacier of greenland

observation and modelling of the saint etienne de tinee landslide using sar interferometry abstract six different interferograms of the la clapiere landslide were derived from ers 1 sar images during the period aug 20 sept 4 1991 the coherence of the associated images is shown to remain significant over most of the surface of the landslide during the two weeks of the survey the interferograms are remarkably similar and indicate steady state displacements over at least 12 days the displacement field derived from the interferograms is shown to be characterized by a non uniform displacement gradient from top to bottom and reveals a significantly faster motion of the western part of the landslide the amplitude of the motion deduced from interferometry is shown to be in good agreement with ground measurements finally sar interferometry is shown to be able to evidence small scale instabilities which may not be observed with discrete ground measurements

measuring two dimensional movements using a single insar pair 1 we present a new method to extract along track displacements from insar data based on split beam insar processing to create forward and backward looking interferograms the phase difference between the two modified interferograms provides the along track displacement component thus from each conventional insar pair we extract two components of the displacement vector one along the line of sight the other in the along track direction we analyze the precision of the new method by comparing our solution to gps and offset derived along track displacements in interferograms of the 1999 hector mine earthquake the rms error between gps displacements and our results ranges from 5 to 8 8cm our method is consistent with along track displacements derived by pixel offsets which are limited to 12 15cm precision the theoretical precision of the new method depends on snr and coherence for a signal to noise ratio of 30 the expected precisions are 3 11cm for coherence of 0 8 0 4 respectively

deformation of the baige landslide tibet china revealed through the integration of cross platform alos palsar 1 and alos palsar 2 sar observations

evaluating sub pixel offset techniques as an alternative to d insar for monitoring episodic landslide movements in vegetated terrain article spaceborne synthetic aperture radar sar sensors obtain regular and frequent radar images from which ground motion can be precisely detected using a variety of different techniques the ability to measure slope displacements remotely over large regions can have many uses although the limitations of the most common place technique differential insar d insar must be considered prior to interpreting the final results one such limitation is the assumption that different rates of movement over a given distance cannot exceed a thresh old value dependent upon the pixel spacing of the sar images and the radar wavelength characteristic features of landslides i e the sharp boundary between stable active ground and the range of temporally variable veloc ities can exhibit high spatial displacement gradients breaking a fundamental assumption for reliable d insar analysis areas of low coherence are also known to hinder the exploitation of insar data this study assesses the capability of terrasar x spotlight terrasar x stripmap and envisat stripmap images for monitoring the slow moving shuping landslide in the densely vegetated three gorges region china in this case study the epi sodic nature of movement is shown to exceed the measurable limit for regular d insar analysis even for the highest resolution 11 day tsx spotlight interferograms a sub pixel offset time series technique applied to cor ner reflectors spot cr using only the sar amplitude information is applied as a robust method of resolving time varying displacements with verifiable offset measurements presented from tsx spotlight and tsx