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

resolving three dimensional surface displacements from insar measurements a review abstract one dimensional measurement along the line of sight los direction has greatly limited the capability of insar technique in the investigation of surface displacements and their dynamics in recent years great efforts have been made to resolve complete three dimensional 3 d displacements from insar measurements this contribution is intended to provide a systematic review of the progress achieved in this field based on an analysis of the insar los measurements we first cover two commonly used techniques i e offset tracking and multi aperture insar mai with which the surface displacement in the azimuth direction can be measured together with the los displacement several methods for mapping 3 d displacements using insar measurements are subsequently presented and categorized into three groups i combination of multi pass los and azimuth measurements ii integration of insar and gps data and iii prior information assisted approaches the strengths and weaknesses of each method are analyzed to show the applicability of each method to specific 3 d displacement mapping cases in hope to provide a useful guidance in choosing a suitable approach accordingly finally suggestions for resolving the challenging issues and outlook of future research are given

origin of methane in high arsenic groundwater of taiwan evidence from stable isotope analyses and radiocarbon dating abstract groundwaters in the confined aquifers of the chianan and ilan coastal plains of taiwan are rich in dissolved methane ch4 serious endemic blackfoot disease which occurred in the chianan plain especially during ad1950 1970 has been demonstrated to have arisen from drinking highly reducing groundwater with abnormal arsenic and humic substance levels in order to explore the origin of ch4 and its hydrological implications stable carbon isotope ratios 13c and radiocarbon 14c ages of exsolved ch4 dissolved inorganic carbon dic and sedimentary biogenic sediments from a total of 34 newly completed water wells at 16 sites were determined the main results obtained are as follows 1 the 13 c ch 4 65 to 75 values indicate that except for one thermogenic sample 13 c ch 4 38 2 from the ilan plain all ch4 samples analyzed were produced via microbially mediated co2 reduction many 13cdic values are considerably greater than 10 and even up to 10 due to rayleigh enrichment during co2 reduction 2 almost all the 14c ages of ch4 samples from the shallow aquifer i

three dimensional surface velocities of storstrommen glacier greenland derived from radar interferometry and ice sounding radar measurements non steady state vertical velocities of up to 5 m y 1 exceed the vertical surface parallel flow components over much of the ablation area of storstrommen a large outlet glacier from the east greenland ice sheet neglecting a contribution to the vertical velocity of this magnitude results in substantial errors up to 20 also on the south north component of horizontal velocities derived by satellite synthetic aperture radar interferometry insar measurements in many glacier environments the steady state vertical velocity component required to balance the annual ablation rate is 5 to 10 m y 1 or more this indicates that the surface parallel flow assumption may be problematic also for glaciers in steady state here we derive the three dimensional surface velocity distribution of storstrommen by using the principle of mass conservation to combine insar measurements from ascending and descending satellite tracks with airborne ice sounding radar measurement of ice thickness the results are compared to insar velocities previously derived by using the assumption of surface parallel flow and to velocities obtained by inin situ gps measurements the velocities derived by using the principle of mass conservation are in better agreement with the gps velocities than the previously calculated velocities derived with the assumption of surface parallel flow

kalman filter based approach for multisensor multitrack and multitemporal insar a kalman filter based approach is presented for resolving 3 d surface displacements using multisensor multitrack and multitemporal interferometric synthetic aperture radar sar measurements measurements from each interferogram are projected into the three reference directions and combined in the kalman filter model with displacements determined from previous interferograms to produce updated displacement measurements both simulated and real data sets are used to test the proposed approach it is found that the method works well when the measurement noise is low the displacements in the north direction however are much lower in accuracy than those in the other two directions and even become unstable when the measurement noise is high due to the polar orbiting imaging geometries of the current satellite sar sensors

coseismic three dimensional displacements determined using sar data theory and an application test we present a methodology to construct three dimensional deformation maps using different parameters that can be extracted using sar data we apply the methodology using envisat sar data before and after the december 26 th 2003 mw 6 6 bam earthquake in iran to determine spatial quasi continuous three dimensional coseismic deformation maps two near vertical deformation offset components are computed using envisat asar differential interferometry dinsar while two horizontal deformation offset components are measured using sub pixel correlation techniques applied to asar amplitude images using the presented methodology we combine four unevenly precise independent projections of surface coseismic deformation to obtain the full three dimensional coseismic deformation field caused by an earthquake the full 3 d coseismic displacement vector is modeled using elastic deformation models constraining details of the fault geometry and slip distribution at depth results from the inversion are interpreted in the framework of the iranian present day tectonism full exploitation of dense 3 d coseismic surface deformation using sar data even for moderate earthquakes should facilitate distinguishing between different interpretations of the mechanical properties of seismically active areas and within the inherent ambiguity of the geophysical inversion solutions

satellite radar interferometry for monitoring ice sheet motion application to an antarctic ice stream satellite radar interferometry sri provides a sensitive means of monitoring the flow velocities and grounding line positions of ice streams which are indicators of response of the ice sheets to climatic change or internal instability the detection limit is about 1 5 millimeters for vertical motions and about 4 millimeters for horizontal motions in the radar beam direction the grounding line detected by tidal motions where the ice goes afloat can be mapped at a resolution of 0 5 kilometer the sri velocities and grounding line of the rutford ice stream antarctica agree fairly well with earlier ground based data the combined use of sri and other satellite methods is expected to provide data that will enhance the understanding of ice stream mechanics and help make possible the prediction of ice sheet behavior

coseismic deformation of the destructive april 6 2009 l aquila earthquake central italy from gps data 1 on april 6 2009 01 32 39 gmt the city of l aquila was struck by a mw 6 3 earthquake that killed 307 people causing severe destruction and ground cracks in a wide area around the epicenter four days before the main shock we augmented the existing permanent gps network with five gps stations of the central apennine geodetic network cageonet bordering the l aquila basin the maximum horizontal and vertical coseismic surface displacements detected at these stations was 10 39 0 45 cm and 15 64 1 55 cm respectively fixing the strike direction according to focal mechanism estimates we estimated the source geometry with a non linear inversion of the geodetic data our best fitting fault model is a 13 15 7 km2 rectangular fault sw dipping at 55 3 1 8 consistent with the position of observed surface ruptures the estimated slip 495 29 mm corresponds to a 6 3 moment magnitude in excellent agreement with seismological data

mass fluxes and dynamics of moreno glacier southern patagonia icefield accumulation ablation calving and flow dynamics of moreno glacier one of the main outlet glaciers of the southern patagonia icefield were studied based on field campaigns and on spaceborne radar imagery acquired by sir c x sar ice velocities and ablation were measured through two summers and one winter the ice depth was sounded seismically at a transect 8 km above the calving front showing a maximum depth of 720 m the velocity field of the terminus was derived from sir c x sar data by means of interferometry and amplitude correlation the average specific annual net accumulation is 5540 500 mm water equivalent the bottom topography of the lake and the high ratio of calving flux to net accumulation explain the remarkable stability of moreno glacier throughout this century which is in contrast to the retreat of other glaciers in this region

the displacement field of the landers earthquake mapped by radar interferometry geodetic data obtained by ground or space based techniques can be used to infer the distribution of slip on a fault that has ruptured in an earthquake although most geodetic techniques require a surveyed network to be in place before the earthquake1 3 satellite images when collected at regular intervals can capture co seismic displacements without advance knowledge of the earthquake s location synthetic aperture radar sar interferometry first introduced4 in 1974 for topographic mapping5 8 can also be used to detect changes in the ground surface by removing the signal from the topography9 10 here we use sar interferometry to capture the movements produced by the 1992 earthquake in landers california11 we construct an interferogram by combining topographic information with sar images obtained by the ers 1 satellite before and after the earthquake the observed changes in range from the ground surface to the satellite agree well with the slip measured in the field with the displacements measured by surveying and with the results of an elastic dislocation model as a geodetic tool the sar interferogram provides a denser spatial sampling 100 m per pixel than surveying methods1 3 and a better precision 3 cm than previous space imaging techniques12 13

detection of aquifer system compaction and land subsidence using interferometric synthetic aperture radar antelope valley mojave desert california interferometric synthetic aperture radar insar has great potential to detect and quantify land subsidence caused by aquifer system compaction insar maps with high spatial detail and resolution of range displacement 10 mm in change of land surface elevation were developed for a groundwater basin 103 km2 in antelope valley california using radar data collected from the ers 1 satellite these data allow comprehensive comparison between recent 1993 1995 subsidence patterns and those detected historically 1926 1992 by more traditional methods the changed subsidence patterns are generally compatible with recent shifts in land and water use the insar detected patterns are generally consistent with predictions based on a coupled model of groundwater flow and aquifer system compaction the minor inconsistencies may reflect our imperfect knowledge of the distribution and properties of compressible sediments when used in conjunction with coincident measurements of groundwater levels and other geologic information insar data may be useful for constraining parameter estimates in simulations of aquifer system compaction

space geodetic investigation of the coseismic and postseismic deformation due to the 2003 mw7 2 altai earthquake implications for the local lithospheric rheology 1 we use envisat advanced synthetic aperture radar data and spot optical imagery to investigate the coseismic and postseismic deformation due to the 27 september 2003 mw7 2 altai earthquake which occurred in the chuya basin near the russia china mongolia border on the basis of the synthetic aperture radar sar and spot data we determined the rupture location and developed a coseismic slip model for the altai earthquake the inferred rupture location is in a good agreement with field observations and the geodetic moment from our slip model is consistent with the seismic moment determined from the teleseismic data while the epicentral area of the altai earthquake is not optimal for radar interferometry in particular due to temporal decorrelation we were able to detect a transient signal over a time period of 3 years following the earthquake the signal is robust in that it allows us to discriminate among several commonly assumed mechanisms of postseismic relaxation we find that the postearthquake interferometric sar data do not warrant poroelastic rebound in the upper crust the observed deformation also disagrees with linear viscoelastic relaxation in the upper mantle or lower crust giving rise to a lower bound on the dynamic viscosity of the lower crust of the order of 1019 pa s the data can be explained in terms of fault slip within the seismogenic zone on the periphery of areas with high coseismic slip most of the postseismic deformation can be explained in terms of seismic moment release in aftershocks some shallow slip may have also occurred aseismically therefore the observed postseismic deformation due to the altai earthquake is qualitatively different from deformation due to other similarly sized earthquakes in particular the landers and hector mine earthquakes in the mojave desert southern california the observed variations in the deformation pattern may be indicative of different rheologic structure of the continental lithosphere in different tectonically active areas

tectonic contraction across los angeles after removal of groundwater pumping effects after the 1987 whittier narrows and 1994 northridge earthquakes revealed that blind thrust faults represent a significant threat to metropolitan los angeles a network of 250 continuously recording global positioning system gps stations was deployed to monitor displacements associated with deep slip on both blind and surface faults here we augment this gps data with interferometric synthetic aperture radar imagery to take into account the deformation associated with groundwater pumping and strike slip faulting after removing these non tectonic signals we are left with 4 4 mm yr 1 of uniaxial contraction across the los angeles basin oriented n 36 degrees e perpendicular to the major strike slip faults in the area this indicates that the contraction is primarily accommodated on thrust faults rather than on the northeast trending strike slip faults we have found that widespread groundwater and oil pumping obscures and in some cases mimics the tectonic signals expected from the blind thrust faults in the 40 km long santa ana basin groundwater withdrawal and re injection produces 12 mm yr 1 of long term subsidence accompanied by an unprecedented seasonal oscillation of 55 mm in the vertical direction and 7 mm horizontally

ice velocity determined using conventional and multiple aperture insar abstract we combine conventional interferometric synthetic aperture radar insar and multiple aperture insar mai to determine the ice surface velocity on the langjokull and hofsjokull ice caps in iceland in 1994 this approach allows the velocity of the 20 principal ice cap outlet glaciers to be fully resolved we show that mai leads to displacement estimates of finer resolution 15 versus 150 m and superior precision 5 versus 15 cm to those afforded by the alternative technique of speckle tracking using sar data acquired in ascending and descending orbits we show that ice flows within 15 of the direction of maximum surface slope across 66 of the ice caps it is therefore possible to determine ice displacement over the majority of the ice caps using a single sar image pair thereby reducing errors associated with temporal fluctuations in ice flow

evidence for subglacial water transport in the west antarctic ice sheet through three dimensional satellite radar interferometry 1 radarsat data from the 1997 antarctic mapping mission are used interferometrically to solve for the 3 dimensional surface ice motion in the interior of the west antarctic ice sheet wais an area of 125 km2 in a tributary of the kamb ice stream slumped vertically downwards by up to 50 cm between september 26 and october 18 1997 areas in the bindschadler ice stream also exhibited comparable upward and downward surface displacements as the uplift and subsidence features correspond to sites at which the basal water apparently experiences a hydraulic potential well we suggest transient movement of pockets of subglacial water as the most likely cause for the vertical surface displacements these results and related lidar observations imply that imaging the change in ice surface elevation can help reveal the key role of water in the difficult to observe subglacial environment and its important influence on ice dynamics

using multiple radarsat insar pairs to estimate a full three dimensional solution for glacial ice movement 1 multiple sar interferograms are used to solve for the full 3 dimensional displacement of the surface of the henrietta nesmith glacier in northern ellesmere island canada the approach exploits the incidence angle flexibility of different ascending and descending beam modes and the azimuth angle diversity which occurs when different incidence angles are used at high latitudes line of sight displacements are estimated in 3 different orientations from the terrain corrected unwrapped differential phase and used to solve for the displacements in a local east north up frame uncertainty in the absolute line of sight displacements limits the absolute accuracy for vertical displacement however the relative solution coupled with knowledge of the surface slope allows spaceborne mapping of relative glacier thickening or thinning with unprecedented spatial resolution and with an accuracy of order a millimeter per day

topography correlated atmospheric delay correction in radar interferometry using wavelet transforms 1 atmospheric delay is one of the major sources of error in repeat pass interferometry we propose a new approach for correcting the topography correlated components of this artifact to this aim we use multiresolution wavelet analysis to identify the components of the unwrapped interferogram that correlate with topography by using a forward wavelet transform we break down the digital elevation model and the unwrapped interferogram into their building blocks based on their frequency properties we apply a cross correlation analysis to identify correlated coefficients that represent the effect of the atmospheric delay thus the correction to the unwrapped interferogram is obtained by down weighting the correlated coefficients during inverse wavelet transform we test this approach on real and synthetic data sets that are generated over the san francisco bay area we find that even in the presence of tectonic signals this method is able to reduce the correlated component of the atmospheric delay by up to 75 and improves the signal in areas of high relief the remaining part is most likely due to 3d heterogeneities of the atmosphere and can be reduced by integrating temporal information or using complementary observations or models of atmospheric delay

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

a joint analysis of gps motions and insar to infer the coseismic surface deformation of the izmit turkey earthquake summary from a joint analysis of gps and insar data we have determined the kinematic coseismic surface deformation of the 1999 august 17 izmit turkey earthquake in terms of strain rotation and fault slip the fault slip contribution shows two distinct peaks one of 4 m of slip at golcuk and a second of 2 9 m slip near sapanca lake the strain field portrays four distinct quadrants reflecting the earthquake focal mechanism the transition between the quadrants is not centred on the epicentre of the event but shifted eastwards north of the fault and westwards south of the fault this shift is the result of a two stage source rupture process caused by the step over features in the fault geometry this rupture process also induced a distinct asymmetry in the displacement field across the fault we obtain left lateral shear strains along the sakarya segment that is the result of a subsequent source nucleating at the akyazi gap inducing failure on the easternmost segments strong interaction is also observed from a consecutive source near hersek finally we deduce that the izmit earthquake has released most of the strain that has accmulated since the last main event on this stretch of the north anatolian fault in 1719

sensing the ups and downs of las vegas insar reveals structural control of land subsidence and aquifer system deformation land subsidence in las vegas nevada united states between april 1992 and december 1997 was measured using spaceborne interferometric synthetic aperture radar the detailed deformation maps clearly show that the spatial extent of subsidence is controlled by geologic structures faults and sediment composition clay thickness the maximum detected subsidence during the 5 75 yr period is 19 cm comparison with leveling data indicates that the subsidence rates declined during the past decade as a result of rising ground water levels brought about by a net reduction in ground water extraction temporal analysis also detects seasonal subsidence and uplift patterns which provide information about the elastic and inelastic properties of the aquifer system and their spatial variability

systematic insar tropospheric phase delay corrections from global meteorological reanalysis data 1 despite remarkable successes achieved by differential insar estimations of low tectonic strain rates remain challenging in areas where deformation and topography are correlated mainly because of the topography related atmospheric phase screen aps in areas of high relief empirical removal of the stratified component of the aps may lead to biased estimations of tectonic deformation rates here we describe a method to correct interferograms from the effects of the spatial and temporal variations in tropospheric stratification by computing tropospheric delay maps coincident with sar acquisitions using the era interim global meteorological model the modeled phase delay is integrated along vertical profiles at the era i grid nodes and interpolated at the spatial sampling of the interferograms above the elevation of each image pixel this approach is validated on unwrapped interferograms we show that the removal of the atmospheric signal before phase unwrapping reduces the risk of unwrapping errors in areas of rough topography

surface deformation from persistent scatterers sar interferometry and fusion with leveling data a case study over the choushui river alluvial fan taiwan abstract the choushui river alluvial fan craf one of the most important agricultural areas in taiwan suffers severe subsidence caused by groundwater withdrawal we use 20 envisat images from 2006 to 2008 to derive vertical deformation over craf by persistent scatterer interferometry psi which effectively reduces errors affecting conventional dinsar techniques the pixel density over craf is 107 6 pixels km 2 compared to 0 19 points km 2 of the leveling benchmarks psi yields vertical displacements matching the leveling result to 0 6 cm year rms and provides a higher spatial resolution of subsidence than the latter we also develop a data fusion method that considers the high precision low point density leveling result as a smoothed correction to the psi result the combined field is more representative of overall deformation characteristics than the psi only or leveling only field and it is better suited for the assessment of the impact of subsidence over craf

mapping small elevation changes over large areas differential radar interferometry a technique that uses synthetic aperture radar sar images to measure very small 1 cm or less surface motions with good resolution 10 m over large swaths 50 km is presented along with experimental results the method could be used for accurate measurements of many geophysical phenomena including swelling and buckling in fault zones residual displacements from seismic events and prevolcanic swelling the method is based on sar interferometry where two images are made of a scene by simultaneously flying two physically separated antennas then the phases of corresponding pixels are differenced and altitude formation is deduced from some simple computation and image rectification it is also possible to use one antenna flown twice over the same scene then if the second flight exactly duplicates the track of the first an interesting possibility occurs there would be no phase changes between the images at all unless there was a physical change in the scene such as ground swelling that would alter the distance from some resolution element to the antenna since the phase changes all occur at the short carrier wavelength the basic limitation on sensitivity is only the phase noise in the system when the two imaging passes are made from flight tracks that are separated which is the case with the seasat images used here it is no longer possible to distinguish surface changes from the parallax caused by topography however with some additional computation a third image made at some other baseline may be used to remove the topography and leave only the surface changes this method was applied using seasat data to an imaging site in imperial valley california where motion effects were observed that were ascribed to the expansion of water absorbing clays phase change images of this area are shown along with associated ground truth about the presence of water problems with the technique are explored along with a discussion of future experimental possibilities on upcoming sar missions like earth observing system eos earth resources satellite ers 1 sir c and the venus imaging radar magellan

a multiscale approach to estimating topographically correlated propagation delays in radar interferograms when targeting small amplitude surface deformation using repeat orbit interferometric synthetic aperture radar insar observations can be plagued by propagation delays some of which correlate with topographic variations these topographically correlated delays result from temporal variations in vertical stratification of the troposphere an approximate model assuming a linear relationship between topography and interferometric phase has been used to correct observations with success in a few studies here we present a robust approach to estimating the transfer function k between topography and phase that is relatively insensitive to confounding processes earthquake deformation phase ramps from orbital errors tidal loading etc our approach takes advantage of a multiscale perspective by using a band pass decomposition of both topography and observed phase this decomposition into several spatial scales allows us to determine the bands wherein correlation between topography and phase is significant and stable when possible our approach also takes advantage of any inherent redundancy provided by multiple interferograms constructed with common scenes we define a unique set of component time intervals for a given suite of interferometric pairs we estimate an internally consistent transfer function for each component time interval which can then be recombined to correct any arbitrary interferometric pair we demonstrate our approach on a synthetic example and on data from two locations long valley caldera california which experienced prolonged periods of surface deformation from pressurization of a deep magma chamber and one coseismic interferogram from the 2007 mw 7 8 tocapilla earthquake in northern chile in both examples the corrected interferograms show improvements in regions of high relief independent of whether or not we pre correct the data for a source model we believe that most of the remaining signals are predominately due to heterogeneous water vapor distribution that requires more sophisticated correction methods than those described here

measuring near field coseismic displacements from sar images application to the landers earthquake we describe a procedure to compute sar interferograms based on the compensation of the images mis registrations due to the ground deformation and on a specific adaptive filtering to improve the snr in the measurement where displacement gradients are large applied to the landers earthquake case the registration reduces the phase noise by 20 rms near the fault and the interferogram reveals fringes that would not show out otherwise the interferogram is validated by comparison in the far field with a gps edm based model the inferred displacement field shows discontinuities that follow the fault within few hundred meters close to the fault the measured displacements differ significantly from that predicted by elastic modeling of the far field data interferometry and measurements derived from the images amplitude offsets appear to be complementary techniques providing original measurements that may help to reconcile seismological and geodetic models of coseismic deformation with measurements of fault slip at the surface

three dimensional glacial flow and surface elevation measured with radar interferometry outlet glaciers which serve to drain ice from ice sheets seem to be dynamically less stable in north greenland than in south greenland1 2 3 storstrommen a large outlet glacier in northeastern greenland which surged between 1978 and 1984 ref 2 has been well studied in general neither glacier surge mechanisms nor the geographical distribution of the surges are well known conventional satellite radar interferometry can provide large scale topography models with high resolution4 and can measure the radar line of sight component of ice flow vectors5 but cannot map full vector flow fields here we present an interferometry method that combines observations from descending and ascending satellite orbits which assuming ice flow parallel to the topographic surface allows us to use the differing view angles to estimate full three dimensional surface flow patterns the accuracy of our technique is confirmed by the good agreement between our radar based flow model and in situ global positioning system gps reference data at storstrommen radar measurements such as these made regularly and at high spatial density have the potential to substantially enhance our understanding of glacier dynamics and ice sheet flow as well as improve the accuracy of glacier mass balance estimates

nonlinear representation of the quasi biennial oscillation a nonlinear principal component analysis nlpca is applied to monthly mean zonal wind observations from january 1956 through december 2007 taken at seven pressure levels between 10 and 70 hpa in the stratosphere near the equator to represent the well known quasi biennial oscillation qbo and investigate its variability and structure the nlpca is conducted using a simplified two hidden layer feed forward neural network that alleviates the problems of nonuniqueness of solutions and data overfitting that plague nonlinear techniques of principal component analysis the qbo is used as a test bed for the new compact model of nlpca the two nonlinear principal components of the dataset of the equatorial stratospheric zonal winds determined by the compact nlpca offer a clear picture of the qbo in particular their structure shows that the qbo phase consists of a predominant 28 3 month cycle that is modulated by an 11 yr cycle as well as by longer cycles the differences in wind variability between westerly and easterly regimes and between northern hemisphere winter and summer seasons and the tendency for a seasonal synchronization of the qbo phases are well captured

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

ionospheric artifacts in simultaneous l band insar and gps observations phase artifacts in interferometric synthetic aperture radar insar images frequently degrade the interpretability of the phase and correlation signatures of terrain often these distortions are attributed to spatially variable ionospheric propagation delays at two different sar acquisition times we present here l band insar data from iceland california and hawaii the california and hawaii interferograms show no significant ionospheric artifacts while the iceland interferogram shows a maximum misregistration of three pixels in the azimuth direction which leads to severe phase decorrelation artifacts in the insar image we relate the misregistration of complex pixels seen in the interferograms to the gradient of the ionospheric total electron content tec observed by global positioning system gps data and confirm that indeed the phase artifacts in the iceland interferogram are due to dispersive ionospheric propagation rather than other decorrelation factors such as neutral atmospheric delays we develop a method to measure the spatial tec variation at synthetic aperture length scales using dual frequency gps carrier phase data we solve for the gps data ambiguities using a low resolution ionosphere reference derived from either available ionospheric observations or the gps carrier phase data themselves gps observations show directly the level of ionospheric variability and the spatial tec gradient as observed by gps predicts the misregistration of complex pixels in interferograms in all three areas this confirmation of the cause of the image artifacts suggests that they can be routinely corrected from the insar data alone provided that the sensor measures the change in tec along the radar swath

analysis of satellite and in situ ground deformation data integrated by the sistem approach the april 3 2010 earthquake along the pernicana fault mt etna italy case study abstract etna is known worldwide as one of the most studied and monitored active volcanoes flank instability along the eastern and southern portions of mt etna has been observed and measured thanks to geodetic networks and insar data analysis the spreading area is bordered to the north by the east west pernicana fault system pfs whose dynamics is often linked with the eruptive activity as recently observed during the 2002 2003 eruption a seismic sequence occurred from april 2 3 2010 along the pfs with very shallow a few hundred meters mainshocks of magnitude 4 3 and 3 6 explosions and ash emissions at the summit craters followed this swarm culminating a few days later april 7 8 despite their small magnitude the earthquakes caused damage and significant surface fracturing along the pfs in order to investigate and measure the deformations in the near field of the earthquakes the sistem integration approach has been exploited the sistem enabled integrating geodetic in situ ground deformation measurements gps and leveling with satellite interferometric measurements envisat and alos in order to obtain high resolution 3d displacement maps allowing to overcome the limitations of each technique and take advantage of the particular features of each of them the integrated ground deformation field evidenced that the medium behave elastically we inverted the sistem results using an optimization algorithm based on the genetic algorithm ga in order to model the kinematics of the pfs associated to seismic swarm the results are in good agreement with the field evidence and improved the knowledge on the kinematics of the pfs and mt etna s unstable flank

three dimensional surface displacement of the 2008 may 12 sichuan earthquake china derived from synthetic aperture radar evidence for rupture on a blind thrust summary the sichuan earthquake mw 7 9 struck the longmen shan lms range front china on 2008 may 12 affecting an area of moderate historical seismicity where little active shortening has been previously reported recent studies based on space geodesy have succeeded in retrieving the far field surface displacements caused by the earthquake but the near field 25 km from the faults coseismic surface displacement is still poorly constrained thus shallow fault geometry and shallow coseismic slip are still poorly resolved here for the first time for this earthquake we combine c and l band synthetic aperture radar offsets data from ascending and descending tracks to invert for the 3 d surface displacement in the near coseismic field of the sichuan earthquake our data coupled with a simple elastic dislocation model provide new results strongly suggesting the presence of a blind thrust striking along the range front and being active at depth during the earthquake the presence of a rupture on a blind thrust brings new evidence for an out of sequence thrusting event and new elements for interpreting the tectonic strain partitioning in the lms which has important implications both for seismic hazard assessment and long term evolution of the mountain belt

topographic mapping from interferometric synthetic aperture radar observations interferometric synthetic aperture radar observations provide a means for obtaining high resolution topographic terrain maps from data acquired simultaneously at two slightly displaced antennas calculation of the three dimensional coordinates of all the points in a radar image can be made from the combination of along track slant range and interferometer fringe measurements thus the result compensates for the layover exhibited by conventional radar maps and removes the false targets generated by multiple signal paths to a given object in the scene we have derived a topographic map of a portion of the san francisco bay area utilizing data that were recorded by a radar system mounted on a nasa cv990 aircraft and processed by a general purpose digital computer this map displays the height above sea level of a region approximately 11 km by 10 km in size sampled on an 11 m pixel grid uncertainties in the estimated height result from imprecise knowledge of the observational geometry radar bandwidth limitations and finite signal to noise ratios for our system each factor contributed approximately 3 4 m to a relative rms error of about 6 m additional global errors of the order of 10 m can result from inaccurate monitoring of aircraft attitude the statistical variation of the height measurements from the ocean portion of the map which we can presume to be quite flat is 2 10 m rms which is consistent with the theoretical estimate comparison of our results with u s geological survey contour maps indicates a high degree of correlation between the two sets of altitude data

high resolution interseismic velocity data along the san andreas fault from gps and insar 1 we compared four interseismic velocity models of the san andreas fault based on gps observations the standard deviations of the predicted secular velocity from the four models are larger north of the san francisco bay area near the creeping segment in central california and along the san jacinto fault and the east california shear zone in southern california a coherence spectrum analysis of the secular velocity fields indicates relatively high correlation among the four models at longer wavelengths 15 40 km with lower correlation at shorter wavelengths to improve the short wavelength accuracy of the interseismic velocity model we integrated interferometric synthetic aperture radar insar observations initially from advanced land observing satellite alos ascending data spanning from the middle of 2006 to the end of 2010 totaling more than 1100 interferograms with gps observations using a sum remove filter restore approach the final insar line of sight data match the point gps observations with a mean absolute deviation of 1 5 mm yr we systematically evaluated the fault creep rates along major faults of the san andreas fault and compared them with creepmeters and alignment array data compiled in uniform california earthquake rupture forecast version 2 ucerf2 moreover this insar line of sight dataset can constrain rapid velocity gradients near the faults which are critical for understanding the along strike variations in stress accumulation rate and associated earthquake hazard

feasibility of along track displacement measurement from sentinel 1 interferometric wide swath mode the european space agency s sentinel 1 a c band imaging radar mission to be launched in mid 2013 will provide a continuity of radar data for monitoring the changing earth the azimuth resolution of sentinel 1 s background mode interferometric wide swath iw mode is four times lower than that of european remote sensing satellite ers and envisat systems therefore the measurement accuracy of along track displacement from sentinel 1 iw images presumably will be significantly reduced in this paper we test the feasibility of along track displacement measurement from sentinel 1 iw mode we simulate sentinel 1 iw synthetic aperture radar sar images from the ers raw data that captured the coseismic deformation of the 1999 hector mine earthquake in california along track displacement maps are generated using multiple aperture interferometric sar mai and intensity tracking techniques respectively and are compared with gps measurements the root mean square rms error between the synthetic sentinel 1 mai and gps measurements is about 9 6 cm which corresponds to only 0 5 of the azimuth resolution the rms error between the along track displacements from synthetic sentinel 1 offset tracking and gps is about 27 5 cm which is about 1 4 of the azimuth resolution these results suggest that the mai method will still be useful to measure along track displacements from sentinel 1 iw insar imagery and that it would be difficult to effectively measure the along track displacements by the sentinel 1 offset tracking method

combining sar interferometry and the equation of continuity to estimate the three dimensional glacier surface velocity vector until now an assumption of surface parallel glacier flow has been used to express the vertical velocity component in terms of the horizontal velocity vector permitting all three velocity components to be determined from synthetic aperture radar interferometry we discuss this assumption which neglects the influence of the local mass balance and a possible contribution to the vertical velocity arising if the glacier is not in steady state we find that the mass balance contribution to the vertical surface velocity is not always negligible as compared to the surface slope contribution moreover the vertical velocity contribution arising if the ice sheet is not in steady state can be significant we apply the principle of mass conservation to derive an equation relating the vertical surface velocity to the horizontal velocity vector this equation valid for both steady state and non steady state conditions depends on the ice thickness distribution replacing the surface parallel flow assumption with a correct relationship between the surface velocity components requires knowledge of additional quantities such as surface mass balance or ice thickness

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

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

insar observations of low slip rates on the major faults of western tibet two contrasting views of the active deformation of asia dominate the debate about how continents deform i the deformation is primarily localized on major faults separating crustal blocks or ii deformation is distributed throughout the continental lithosphere in the first model western tibet is being extruded eastward between the major faults bounding the region surface displacement measurements across the western tibetan plateau using satellite radar interferometry insar indicate that slip rates on the karakoram and altyn tagh faults are lower than would be expected for the extrusion model and suggest a significant amount of internal deformation in tibet