shallow creep on the haiyuan fault gansu china revealed by sar interferometry interferometric synthetic aperture radar data are used to map the interseismic velocity field along the haiyuan fault system hfs at the north eastern boundary of the tibetan plateau two m 8 earthquakes ruptured the hfs in 1920 and 1927 but its 260 km long central section known as the tianzhu seismic gap remains unbroken since 1000 years the envisat sar data spanning the 2003 2009 period cover about 200 300 km2 along three descending and two ascending tracks interferograms are processed using an adapted version of roi pac the signal due to stratified atmospheric phase delay is empirically corrected together with orbital residuals mean line of sight velocity maps are computed using a constrained time series analysis after selection of interferograms with low atmospheric noise these maps show a dominant left lateral motion across the hfs and reveal a narrow 35 km long zone of high velocity gradient across the fault in between the tianzhu gap and the 1920 rupture we model the observed velocity field using a discretized fault creeping at shallow depth and a least squares inversion the inferred shallow slip rate distribution reveals aseismic slip in between two fully locked segments the average creep rate is 5 mm yr 1 comparable in magnitude with the estimated loading rate at depth suggesting no strain accumulation on this segment the modeled creep rate locally exceeds the long term rate reaching 8 mm yr 1 suggesting transient creep episodes the present study emphasizes the need for continuous monitoring of the surface velocity in the vicinity of major seismic gaps in terms of seismic hazard assessment

present day interseismic surface deformation along the longitudinal valley eastern taiwan from a ps insar analysis of the ers satellite archives 1 in taiwan about one third of the lithospheric plate convergence between eurasia and the philippine sea plate is accommodated on the eastern coast across the narrow longitudinal valley lv the longitudinal valley fault lvf is the main seismically active fault zone in this region however the spatial distribution of ground deformation due to interseismic loading on locked fault segments remains widely unknown to address this problem we use a permanent scatterer ps interferometric synthetic aperture radar insar approach for processing the ers satellite archives the ps mean velocity maps allow accurately mapping and quantifying the ground deformation all along the lv assuming that close to the surface the fault plane along the central lvf creeping segment dips 55 to the east we derive a slip vector at the surface of 25 mm yr with a mean rake of 70 in agreement with our ps observations shallow seismicity indicates a clear change in the fault mechanical behavior of the creeping segment around fuli town finally we propose a combination of the ps velocity fields for estimating a 3 d map of ground deformation in the southern part of the lv the vertical component reveals an uplift of the coastal range with respect to the lv of 10 mm yr moreover between taitung and luyeh the vertical deformation is essentially accommodated along the luyeh strand finally north of rueisuei the coastal range uniformly subsides at 15 mm yr relative to the western side of the lv however a local uplift pattern is detected around latitude 23 42

using cosmo skymed x band and envisat c band sar interferometry for landslides analysis abstract we explore new possibilities offered by the recently available x band satellite radar sensors for landslide hazard assessments on a detailed scale with particular reference to the exploitation of persistent scatterers interferometry psi techniques special attention is paid to the impact of the improved resolution of new x band radar imagery on the psi results in terms of quality and quantity of useful information this evaluation is supported by theoretical modelling as well as by the comparison of results from x band csk and c band envisat psi for two areas of interest one in italy and the other in switzerland it is demonstrated that with respect to medium resolution envisat ps processing fewer csk high resolution images are sufficient to achieve comparable precision of the mean displacement velocity estimates this together with the shorter revisit times provided by the csk constellation can be very important when dealing with emergency situations furthermore it is quantified that from about 3 to 11 times greater ps densities are obtained with the higher resolution x band data this implies more information about ground surface displacements as well as improved landslide monitoring and slope instability investigation capabilities furthermore ground displacement measurements can be interpreted without local knowledge of the focus area or in situ controls and nonetheless guide single hillslope instability assessments with support of google earth and its high resolution optical imagery this blind approach will allow one to monitor remote and poorly known regions at high risk of potentially disastrous slope failures

tide model accuracy in the amundsen sea antarctica from radar interferometry observations of ice shelf motion 1 this study assesses the accuracy of tide model predictions in the amundsen sea sector of west antarctica tide model accuracy in this region is poorly constrained yet tide models contribute to simulations of ocean heat transfer and to the removal of tidal signals from satellite observations of ice shelves we use two satellite based interferometric synthetic aperture radar insar methods to measure the tidal motion of the dotson ice shelf at multiple epochs a single difference technique that measures tidal displacement and a double difference technique that measures changes in tidal displacement we use these observations to evaluate predictions from three tide models tpxo7 1 cats2008a opt and fes2004 all three models perform comparably well exhibiting root mean square deviations from the observations of 9 cm single difference technique and 10 cm double difference technique care should be taken in generalizing these error statistics because 1 the dotson ice shelf experiences relatively small semidiurnal tides and 2 our observations are not sensitive to all tidal constituents an error analysis of our insar based methods indicates measurement errors of 7 and 4 cm for the single and double difference techniques respectively a model based correction for the effect of fluctuations in atmospheric pressure yields an 6 improvement in the agreement between tide model predictions and observations this study suggests that tide model accuracy in the amundsen sea is comparable to other antarctic regions where tide models are better constrained these methods can be used to evaluate tide models in other remote antarctic waters

applicability of insar to tropical volcanoes insights from central america measuring volcano deformation is key to understanding the behaviour of erupting vol canoes and detecting those in periods of unrest satellite techniques provide the opportunity to do so on a global scale but with some notable exceptions the deformation of volcanoes in the tropics has been understudied relative to those at higher latitudes largely due to technical difficulties in applying interferometric synthetic aperture radar insar we perform a systematic survey of the central american volcanic arc to investigate the appli cability of interferometric synthetic aperture radar insar to volcanoes in the tropics volcano characteristics that may prevent insar measurement include 1 dense vegetation cover 2 per sistent activity and 3 steep slopes measurements of deformation are further inhibited by atmos pheric artefacts associated with 4 large changes in topographical relief we present a systematic method for distinguishing between water vapour artefacts and true deformation our data show a linear relationship c 2 cm km between the magnitudes of water vapour artefacts and volcano edifice height for high relief volcanoes e g fuego guatemala 3763 m a s l above sea level errors are of the order of 4 5 cm across the volcano s edifice but are less than 2 cm for lower relief e g masaya nicaragua 635 m a s l examples such as arenal atitlan and fuego illustrate that satellite acquisition strategies incorporating ascending and descending tracks are particularly important for studying steep sided volcanoes poor coherence is primarily associated with temporal decorrelation which is typically more rapid in southern central america where evergreen broadleaf vegetation dominates land use classification is a better predictorof decorrelation rate thanvegetationindex comparisonof coher ence for different radar wavelengths match expectations high resolution x band radar is best suited to local studies where high resolution digital elevation models dems exist while l bandwavelengths are necessary for regional surveys however this is the first time that relation ships between phase coherence and time perpendicular baseline radar wavelength and land use have been quantified on the scale of a whole volcanic arc

crustal deformation associated with an m8 1 earthquake in the solomon islands detected by alos palsar abstract on april 1 2007 utc a large mw 8 1 interplate earthquake struck the solomon islands subduction zone where complicated tectonics result from the subduction of four plates extensive ground movements and a large tsunami occurred in the epicentral area causing severe damage over a wide area using alos palsar data and the dinsar technique we detected crustal deformation exceeding 2 m in islands close to the epicenter a slip distribution of the inferred seismic fault was estimated using geodetic information derived from dinsar processing and field investigations the result indicates large slip areas around the hypocenter and the centroid it is possible that the largest slip area is related to subduction of the plate boundary between the woodlark and australian plates a small slip area between those large slip areas may indicate weak coupling due to thermal activity related to volcanic activity on simbo island the 2007 earthquake struck an area where large earthquake has not occurred since 1970 most of this seismic gap was filled by the 2007 events however a small seismic gap still remains in the southeastern region of the 2007 earthquake

observations modeling and applications of ers envisat coherence over land surfaces european remote sensing satellite ers envisat coherence is a new repeat pass interferometric synthetic aperture radar product characterized by a very short repeat pass interval between acquisitions 28min in this paper we investigate the properties of two 28 mins coherence images acquired over the regions of paris france and prague czech republic as well as a 35 day coherence image from prague bare soils showed higher coherence compared to forests and urban areas the range of coherence was larger for 28 min pairs perpendicular baseline closer to 2km and stable weather conditions between acquisitions coherence modeling shows that because of the long baseline 1 significant surface decorrelation occurs when slopes are not accounted for in the common band filtering and for variation of topography in the resolution cell and 2 volume decorrelation is significant temporal decorrelation seems to be relevant for vegetation even at the 28 min interval time scale observations and modeled coherence were found to be in good agreement land cover classification using coherence and backscatter has been tested for the paris scene for mapping the four major classes the classification accuracy was 86 when an edge eroded version of the reference land cover map was used it decreases to 68 when the full land cover map was used as reference because of local mismatches between the coherence image and the land cover map and the reduced common band in range the high coherence difference between forests and bare fields suggests the possibility to use the ers envisat coherence for forest nonforest mapping and estimation of biophysical properties of short vegetation coherence decorrelation envisat advanced synthetic aperture radar asar european remote sensing satellite ers land cover synthetic aperture radar interferometry insar

single and multipolarimetric sar tomography of forested areas a parametric approach in this paper a technique is described for the tomographic characterization of forested areas through multiple synthetic aperture radar sar observations based on either single or multipolarimetric acquisitions this technique is based on the idea of characterizing the fourier spectrum of the multibaseline data as being constituted by two effective scattering centers displaced along the vertical direction plus the associated decorrelation terms as a result sar tomography will be formulated as the problem of detecting the number of scattering centers within the resolution cell estimating the parameters that describe their spatial structure and evaluating the associated backscattered powers parameter estimation is carried out through the covariance matching estimation technique which provides an asymptotically optimal solution the results of an experiment performed on a real p band multibaseline fully polarimetric data set relative to the forested site of remningstorp sweden are reported

decorrelation in interferometric radar echoes a radar interferometric technique for topographic mapping of surfaces implemented utilizing a single synthetic aperture radar sar system in a nearly repeating orbit is discussed the authors characterize the various sources contributing to the echo correlation statistics and isolate the term which most closely describes surficial change they then examine the application of this approach to topographic mapping of vegetated surfaces which may be expected to possess varying backscatter over time it is found that there is decorrelation increasing with time but that digital terrain model generation remains feasible the authors present such a map of a forested area in oregon which also includes some nearly unvegetated lava flows such a technique could provide a global digital terrain map

a tethered interferometric synthetic aperture radar sar for a topographic mission analyzes a spaceborne interferometric synthetic aperture radar sar for high resolution topographic applications two physical antennas are vertically spaced and are carried along parallel paths by two different platforms connected by a tether tethered space systems have been proposed by several authors for different applications and a joint us italian program exists to deploy in 1992 a small satellite tethered satellite system from a space shuttle a system performance analysis is carried out considering a theoretical study and a numerical simulation by evaluating the tethered interferometric sar impulse response the height of various point scatterers is computed and an error budget is obtained results show that this system is capable of achieving a root mean square rms error in height measurement adequate for several applications

space geodetic determination of spatial variability in relative sea level change los angeles basin 1 we combine synthetic aperture radar interferometry insar tide gauge and continuous gps measurements to determine the spatial variation in vertical land motion vlm along the coast of the los angeles basin over the past decade and to examine the impact of spatially variable vlm on relative sea level trends by identifying radar scattering targets with long term coherence we make height corrections which allow interferogram creation for nearly the entire ers 1 catalog and permit estimation of average deformation rates with minimal temporal aliasing between los angeles harbor and newport beach mean vlm trends range from 3 4 to 4 3 mm yr reflecting the high level of ground water and oil extraction activity in the region west of los angeles harbor vlm rates and spatial variability are roughly half as large the 8 year vlm trends exceed the long term sea level trend 0 8 mm yr determined from the 80 year los angeles harbor tide gauge the high degree of observed vlm variability emphasizes the need for the spatially continuous measurements provided by insar a single tide gauge assessment of regional rsl would otherwise have limited applicability

estimation of seismic and aseismic deformation in mexicali valley baja california mexico in the 2006 2009 period using precise leveling dinsar geotechnical instruments data and modeling ground deformation and seismicity in mexicali valley baja california mexico the southern part of the mexicali imperial valley are influenced by active tectonics and human activity in this study data from two successive leveling surveys in 2006 and 2009 2010 are used to estimate the total deformation occurred in mexicali valley during 2006 2009 the leveling data span more than 3 5 years and include deformation from several natural and anthropogenic sources that acted at different temporal and spatial scales during the analyzed period because of its large magnitude the aseismic anthropogenic deformation caused by fluid extraction in the cerro prieto geothermal field obscures the deformation caused by other mechanisms and sources the method of differential interferograms stacking was used to estimate the aseismic interseismic tectonic and anthropogenic components of the observed displacement using sar images taken in 2007 during a period when no significant seismicity occurred in the study area after removing the estimated aseismic signal from the leveling data residual vertical displacement remained and to identify possible sources and mechanisms of this displacement a detailed analysis of records from tiltmeters and creepmeters was performed the results of this analysis suggest that the residual displacement is mainly caused by moderate sized seismicity in the area of study modeling of the vertical ground deformation caused by the coseismic slip on source fault primary mechanism of the two most important earthquakes may 24 2006 mw 5 4 and december 30 2009 mw 5 8 was performed the modeling results together with the analysis of geotechnical instruments data suggests that this moderate sized seismicity influences the deformation in the study area by coseismic slip on the source fault triggered slip on secondary faults and soft sediments deformation

monitoring of slow ground deformation by ers radar interferometry on the vauvert salt mine france comparison with ground based measurement the differential sar interferometry dinsar technique has been applied to a test site near vauvert france to detect and monitor ground deformation this site corresponds to the location of an industrial exploitation of underground salt using the solution mining technique an area of subsidence has been observed using in situ measurements despite conditions unfavorable for insar because of the vegetal cover we show that radar remote sensing observations provide valuable information which substantially improves our knowledge of the phenomenon an adaptive phase filtering process has been used to improve the coherence level in particular our study shows that the geometry of the subsidence bowl is different to that previously assumed using ground based techniques only the size of the subsidence bowl 8 km is larger than expected this information will be useful for further modeling of the deformation and to improve the coverage of the in situ measurement networks it also shows that radar interferometry can be used for the long term monitoring of such sites and to predict potential environmental issues

coherence and amplitude based analysis of seismogenic damage in bam iran using envisat asar data the sensitivity of synthetic aperture radar sar and interferometric sar insar to surface properties especially changes in height and roughness combined with an all weather capability makes radar remote sensing a potential tool for mapping urban damage caused by earthquakes with insar surface displacement has been mapped successfully and in detail but for urban damage mapping results have so far been less conclusive envisat advanced sar images of bam iran that were acquired before and after the 2003 earthquake were used between preseismic and coseismic image pairs coherence decreased with increasing damage levels however contrary to previous studies earthquake damage caused both increases and decreases in amplitude therefore its absolute value which correlated with damage level was used individually coherence difference led to better results than absolute amplitude change although still with limited accuracy the combination of both resulted in an overall accuracy of 52 since vegetation causes decorrelation a predisaster advanced spaceborne thermal emission and reflection radiometer image was used to mask out vegetated areas which improved the accuracy by 4 the ground truth map showed damage levels per district instead of per pixel therefore the ratio of pixels classified as damage and nondamage was calculated for each damage class of the map and a clear relation was found this shows that the aggregation level of the map partly explains the low accuracy figures of the pixel based evaluation although improvement was made insar techniques for urban damage mapping do not yet provide the accuracy levels needed for disaster mitigation however substantial improvements can be expected from instruments with higher spatial resolution such as the recently launched phased array type l band sar and terra sar x

simulation of the supersar multi azimuth synthetic aperture radar imaging system for precise measurement of three dimensional earth surface displacement the supersar imaging system a novel multi azimuth synthetic aperture radar sar system capable of detecting earth surface deformation in three dimensions from a single satellite platform has recently been proposed in this paper we investigate the feasibility of detecting precise 3 d surface displacement measurements with the supersar imaging system using a point target simulation from this simulation we establish both a relationship between the interferometric sar phase and the across track displacement and a relationship between the multiple aperture interferometry phase and the along track displacement based on the supersar imaging geometry the theoretical uncertainties of the supersar measurement are analyzed in the across and along track directions and the theoretical accuracy of the 3 d displacement measurement from the supersar system is also investigated according to both the decorrelation and the squint and look angles in the case that the interferometric coherence is about 0 8 and that five effective looks are employed the theoretical 2 d measurement precision values are about 3 67 and 6 35 mm in the across and along track directions respectively and the theoretical 3 d measurement precision values for 3 d displacement are about 4 05 4 56 and 3 45 mm in the east north and up directions respectively the result of this study demonstrates that the supersar imaging system is capable of measuring the 3 d surface displacement in all directions with subcentimeter precision

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

mapping inflation at santorini volcano greece using gps and insar 1 recent studies have indicated that for the first time since 1950 intense geophysical activity is occurring at the santorini volcano here we present and discuss the surface deformation associated with this activity spanning from january 2011 to february 2012 analysis of satellite interferometry data was performed using two well established techniques namely persistent scatterer interferometry psi and small baseline subset sbas producing dense line of sight los ground deformation maps the displacement field was compared with gps observations from 10 continuous sites installed on santorini results show a clear and large inflation signal up to 150 mm yr in the los direction with a radial pattern outward from the center of the caldera we model the deformation inferred from gps and insar using a mogi source located north of the nea kameni island at a depth between 3 3 km and 6 3 km and with a volume change rate in the range of 12 million m3 to 24 million m3 per year the latest insar and gps data suggest that the intense geophysical activity has started to diminish since the end of february 2012

validation of the shuttle radar topography mission height data the shuttle radar topography mission srtm provided data for detailed topographical maps of about 80 of the earth s land surface srtm consisted of single pass c and x band interferometric synthetic aperture radars insars in order to utilize srtm data in remote sensing applications the data must be calibrated and validated this paper presents the university of michigan s srtm calibration and validation campaign and our results using recently acquired c band srtm data of our calibration sites an array of calibration targets was deployed with the intention of determining the accuracy of insar derived digital elevation maps the array spanned one of the x band swaths and stretched from toledo oh to lansing mi passive and active targets were used the passive targets included trihedrals and tophats the locations in latitude longitude and elevation of the point targets were determined using differential gps we also acquired u s geological survey usgs digital elevation models dems to use in the calibration and validation work the srtm data used in this study are both principal investigator processor pi data which are not the refined final data product and the ground data processing system gdps data which are a more refined data product we report that both datasets for southeastern michigan exceed the srtm mission specifications for absolute and relative height errors for our point targets a more extensive analysis of the srtm gdps data indicates that it meets the absolute and relative accuracy requirements even for bare surface areas in addition we validate the pi height error files which are used to provide a statistical characterization of the difference between the srtm gdps and usgs dem heights the statistical characterization of the gdps usgs difference is of interest in forest parameter retrieval algorithms

an improvement of the performance of multiple aperture sar interferometry mai multiple aperture synthetic aperture radar sar interferometry mai enables the measurement of along track surface deformations by means of split beam sar processing this paper examines the effects of flat earth and topographic phases on the mai phase and derives formulas to correct them detailed mai processing steps are introduced and discussed with particular consideration given to coherence improvement as well as to computational efficiency forward and backward looking mai pairs have different perpendicular baselines which play a key role in phase distortion consequently an orbital deviation of only a few centimeters could result in a significant flat earth phase a second order polynomial model was used to estimate the perpendicular baseline difference european remote sensing 2 satellite sar data sets of the hector mine earthquake event in 1999 were used for performance evaluation the proposed processing with the flat earth and topographic phase corrections achieved precision of along track deformation ranging from 10 2 to 13 1 cm two coseismic pairs were compared and the standard deviation of the difference between the two independent measurements was 7 0 cm with a mean difference of 0 24 cm thus the measurement accuracy of mai was improved using flat earth correction and coherence enhancement

importance of convective mixing in seasonal ice margin simulations a two dimensional ice ocean model applicable to the greenland sea is constructed and used to examine the role of penetrative convection in the seasonal advance and retreat of the sea ice margin the standard version of the model is based on the full dynamic and thermodynamic equations of sea ice and on the primitive equations discretized on a vertical slab for the ocean it includes a special treatment of upper ocean vertical mixing based on a parameterization of entrainment at the bottom of the ocean mixed layer the simulation results with this standard version of the model show that when ice advection is included with ice moving outward over open water penetrative convection delays and greatly reduces the ice edge advance the resulting seasonal ice distribution yields better agreement with observation than a simulation that does not allow mixed layer entrainment when lateral heat transport is neglected in the ocean the ice margin again moves too a great extent outward this result demonstrates that in addition to vertical mixing a heat source must exist in the ocean mixed layer in order to resist and ultimately stop the advection of ice finally in the absence of ice motion penetrative convection has a less pronounced effect on the ice edge location

measuring large topographic change with insar lava thicknesses extrusion rate and subsidence rate at santiaguito volcano guatemala lava flows can produce changes in topography of the order of 10s 100s of metres a knowledge of the resulting volume change provides evidence about the dynamics of an eruption using differential insar phase delays it is possible to estimate height differences between the current topography and a digital elevation model dem this does not require a pre event sar image so it does not rely on interferometric phase remaining coherent during eruption and emplacement synthetic tests predict that we can estimate lava thicknesses of as little as 9 m given a minimum of five interferograms with suitably large orbital baseline separations in the case of continuous motion such as lava flow subsidence we invert interferometric phase simultaneously for topographic change and displacement we apply this to santiaguito volcano guatemala and measure increases in lava thickness of up to 140 m between 2000 and 2009 largely associated with activity between 2000 and 2005 we find a mean extrusion rate of 0 437 0 06 m

modeling and observation of the radar polarization signature of forested areas to understand radar measurements of forested areas the authors have developed a model of l band 25 cm microwave scattering from a forest the forest floor is layer of nearly vertical dielectric cylinders representing tree trunks above this layer is a second layer consisting of randomly oriented cylinders which represent branches the authors identify several scattering mechanisms and calculate the corresponding stokes matrices which combine to give the total stokes matrix and resulting polarization signature it is found that this simple model permits accurate prediction of the polarization of the scattered waves and that additional mechanisms including the effects of leaves and twigs are not required for the 25 cm observation of the forests studied the authors present measurements of the polarization signature acquired over a forested area and show comparisons with model calculations

permanent scatterers analysis for atmospheric correction in ground based sar interferometry ground based synthetic aperture radar gb sar interferometry has already been recognized as a powerful tool complementary or alternative to spaceborne sar interferometry for terrain monitoring and for detecting structural changes in buildings it has been noted that in spite of the very short range compared with the satellite configuration in gb sar measurement the disturbances due to atmospheric effects cannot be neglected either the analysis of the interferometric phases of very coherent points called permanent scatterers pss allows the evaluation of the atmospheric disturbance and the possibility of removing it in this paper the ps analysis is carried out both on a test site facility and on a real campaign citrin valley italy that provided data with a temporal baseline of about ten months

volumetric change quantification of the 2010 merapi eruption using tandem x insar abstract accurate and up to date information on the time varying topography of active volcanoes is crucial for assessing material flows through these volcanic systems and along their surfaces as dome building volcanoes can change on meter scale within short time intervals in active phases conventionally used repeat pass sar interferometry insar often fails due to decorrelation effects while other methods to measure topography like aerial photogrammetry or lidar depend on the availability of the local infrastructure and on good weather conditions here we show the potential of the spaceborne earth observation mission tandem x to monitor topographic changes at active dome building volcanoes in this innovative satellite mission two nearly identical satellites fly in a close formation taking radar images of the earth s surface at the same time in bistatic mode this opens the possibility to generate digital elevation models dems of volcanoes analyzing a series of repeated dems enables assessment of volume changes caused by lava dome activity we apply this method to merapi in indonesia by analyzing the volume changes during the hazardous 2010 eruption during this eruption the old lava dome collapsed and a new lava dome was extruded which collapsed again within twelve days we show three dems derived from bistatic tandem x insar in descending orbit taken before and after the eruption we found a mean volume change of 19 10 6 m 3 in the summit area the two estimates differ by 0 4 10 6 m 3 which is 2 of the average dome volume change the tandem x based results are about 25 lower than reference data which can be explained by the shadow masks that were introduced to exclude geometrically decorrelated areas resulting in conservative volume change estimates

estimating temporal changes in hydraulic head using insar data in the san luis valley colorado the sustainability of the confined aquifer system in the san luis valley colorado is of utmost importance to the valley s agricultural economy there is a dearth of hydraulic head measurements in the confined aquifer to which the current groundwater flow model can be calibrated here we investigate the extent to which spatially and temporally dense measurements of deformation from interferometric synthetic aperture radar insar data can be used to fill in spatial and temporal gaps in the head data set by calibrating the insar data with head at the monitoring well locations we conduct this calibration at 11 wells where we expect sufficient deformation for reliable insar measurement given the accepted level of uncertainty 1 cm in the san luis valley crop growth degrades the quality of the insar signal which means that the high quality deformation data may not be collocated with the wells we use kriging to estimate the deformation directly at the well locations we find that the calibration is valid at three well locations where the seasonal magnitude of the deformation is much larger than the uncertainty of the insar measurement at these well locations we predict head prior to and within the temporal sampling window of the head measurements we find that 59 of the insar predicted hydraulic head values agree with the measured values within the uncertainty of the data given our success in extending the hydraulic head data temporally the next step in our research is to use insar data to interpolate spatially between head measurements

coseismic deformation of the 2001 mw 7 8 kokoxili earthquake in tibet measured by synthetic aperture radar interferometry the 14 november 2001 m w 7 8 kokoxili earthquake ruptured more than 400 km of the westernmost stretch of the left lateral kunlun fault in northern tibet interferometric synthetic aperture radar data from descending orbits along four adjacent tracks covering almost the entire rupture and 1 m pixel ikonos satellite images are used to map the rupture geometry and the surface displacements produced by the event interferograms are then inverted to solve for coseismic slip on the fault at depth the radar data show that the rupture connected the heituo fault where the earthquake initiated to the main kunlun fault cutting across a pull apart trough in between the two strike slip faults the fault model includes two vertical sections extending to a depth of 20 km and discretized into 5 km 5 km patches using a nonnegative least squares method that includes an appropriate degree of smoothing we solve for the left lateral slip on each fault patch our solution shows that the largest slip occurred at depths between 0 and 5 km reaching 8 m in two areas 200 and 250 km east of the earthquake epicenter significant slip took place below 10 km at both ends of the rupture slip appears to have been highly variable along the fault defining six sections of major moment release these sections correspond to six subsegments of the kunlun fault system defined from the surface morphology of the fault this suggests that fault geometry exerted a predominant influence on controlling the rupture propagation

phase gradient approach to stacking interferograms the phase gradient approach is used to construct averages and differences of interferograms without phase unwrapping our objectives for change detection are to increase fringe clarity and decrease errors due to tropospheric and ionospheric delay by averaging many interferograms the standard approach requires phase unwrapping scaling the phase according to the ratio of the perpendicular baseline and finally forming the average or difference however unique phase unwrapping is usually not possible since the phase gradient due to topography is proportional to the perpendicular baseline phase unwrapping is unnecessary prior to averaging or differencing phase unwrapping may be needed to interpret the results but it is delayed until all of the largest topographic signals are removed we demonstrate the method by averaging and differencing six interferograms having a suite of perpendicular baselines ranging from 18 to 406 m cross spectral analysis of the difference between two tandem interferograms provides estimates of spatial resolution which are used to design prestack filters a wide range of perpendicular baselines provides the best topographic recovery in terms of accuracy and coverage outside of mountainous areas the topography has a relative accuracy of better than 2 m residual interferograms single interferogram minus stack have tilts across the unwrapped phase that are typically 50 mm in both range and azimuth reflecting both orbit error and atmospheric delay smaller scale waves with amplitudes of 15 mm are interpreted as atmospheric lee waves a few global positioning system gps control points within a frame could increase the precision to 20 mm for a single interferogram further improvements may be achieved by stacking residual interferograms

modal synthesis of high frequency waves in scotland summary local recordings on the 1974 lispb array of a shock from an earthquake series in nw scotland show a well developed sg wavegroup and higher mode coda using the results of previous work on the group velocity dispersion of the higher mode surface waves a synthetic seismogram study is carried out to obtain a revised estimate of the depth of the event and investigate the nature of the rupture process high frequency up to 5hz synthetic seismograms are constructed using a modal summation technique these indicate that a fault model consisting of a single rupture is inconsistent and that a more appropriate description consists of two components the main component corresponds to an event at a depth of 10 km and the other a weaker source acting at 0 5 km this result may be interpreted as a double event both sources occurring on the pre existing strathconan fault with a lateral separation of about 2 km or a consequence of scattering from buried heterogeneities in the upper crust

integrated satellite interferometry tropospheric noise gps estimates and implications for interferometric synthetic aperture radar products interferometric synthetic aperture radar insar like other astronomic and space geodetic techniques is limited by the spatially and temporally variable delay of electromagnetic waves propagating through the neutral atmosphere statistical analysis of these variations from a wide variety of instruments reveals a power law dependence on frequency that is characteristic of elementary kolmogorov turbulence a statistical model for a major component of the delay fluctuations the wet component has previously been developed by treuhaft and lanyi 1987 for very long baseline interferometry a continuous global positioning system gps network is now in place in southern california that allows estimation of along with geodetic parameters the total delay due to the atmosphere above each site on a subhourly basis these measurements are shown to conform to the treuhaft and lanyi tl statistical model both temporally and spatially the tl statistical model is applied to the problem of insar and used to produce the covariance between two points separated in time and or space the error due to the atmospheric variations for sar products such as topography and surface deformation is calculated via propagation of errors there are two methods commonly cited to reduce the effect of atmospheric distortion in products from sar interferometry stacking and calibration stacking involves averaging independent interferograms to reduce the noise calibration involves removing part or all of the delay using data from an independent source such as total zenith delay estimates from continuous gps networks despite the relatively poor spatial density of surface measurements calibration can be used to reduce noise if the measurements are sufficiently accurate reduction in tropospheric noise increases with increasing number of measurement points and increasing accuracy up to a maximum of n where n is the number of points stacking and calibration are shown to be complementary and can be used simultaneously to reduce the noise to below that achievable by either method alone

analysis of active lava flows on kilauea volcano hawaii using sir c radar correlation measurements precise eruption rates of active pahoehoe lava flows on kilauea volcano hawaii have been determined using spaceborne radar data acquired by the space shuttle imaging radar c sir c a coastal site downslope from the pu9u o9o vent was imaged once per day on each of the four days of october 7 10 1994 day to day decorrelation due to resurfacing was determined by interferometric combination of the data at 15 m resolution over a wide area on successive days new lava resurfaced 335700 m 2 368775 m 2 and 356625 m 2 assuming an average pahoehoe flow thickness of 50 cm a mean effusion rate for this period is approximately 2 m 3 s the radar observations show persistent surface activity at each site rather than downslope migration of coherent lava flows

mapping arctic landfast ice extent using l band synthetic aperture radar interferometry in recent years methods have been developed to extract the seaward landfast ice edge from series of remote sensing images with most of them relying on incoherent change detection in optical infrared or radar amplitude imagery while such approaches provide valuable results some still lack the required level of robustness and all lack the ability to fully automate the detection and mapping of landfast ice over large areas and long time spans this paper introduces an alternative approach to mapping landfast ice extent that is based on coherent processing of interferometric l band synthetic aperture radar sar data the approach is based on a combined interpretation of interferometric phase pattern and interferometric coherence images to extract the extent and stability of landfast ice due to the low complexity of the base imagery used for landfast ice extraction significant improvements in automation and reduction of required manual interactions by operators can be achieved a performance analysis shows that l band interferometric sar insar data enable the mapping of landfast ice with high robustness and accuracy for a wide range of environmental conditions

analysis of ground deformation detected using the sbas dinsar technique in umbria central italy ground deformation affecting the umbria region central italy in the 9 year period from 1992 to 2000 was investigated through multi temporal differential synthetic aperture radar interferometry dinsar for the purpose the small baseline subset sbas technique was adopted which allows studying the temporal evolution of the detected deformation at two spatial scales a low resolution regional scale and a full resolution local scale for the analysis sar data acquired by the european remote sensing ers 1 2 satellites along ascending and descending orbits were used the detected deformation was analysed to investigate its relevance to geophysical geomorphologic and human induced processes that may result in hazardous conditions to the population of umbria low resolution deformation data were used to i determine the amount of displacement caused by the umbria marche earthquake sequence from september 1997 to april 1998 in the foligno area ii determine the number and percentage of the known landslides that can be monitored by the dinsar technology in the investigated area and iii identify and measure subsidence induced by exploitation of a confined aquifer in the valle umbra results indicate that earthquakes moved through the foligno area westwards up to 3 9 cm and with an uplift reaching 1 7 cm intersection in a gis of the low resolution deformation maps with a detailed landslide inventory map allowed the determination that the portion of landslides that can be monitored by the sbas dinsar technique in umbria ranges from 2 7 to 3 4 and the percentage of the total landslide area ranges from 10 4 to 12 8 in the valle umbra a dependency was found between the time and the amount of detected ground deformation and the record of water withdrawal the full resolution deformation data were used to investigate the movement of the ivancich landslide in the assisi municipality joint analysis of the spatial and the temporal characteristics of the ground displacement allowed the formulation of a hypothesis on the landslide geometry and deformation pattern

integrated analysis of sar interferometric and geological data for investigating long term reclamation settlement of chek lap kok airport hong kong abstract we investigated the long term reclamation settlement of chek lap kok airport hong kong one of the largest reclamation projects worldwide an advanced insar technique was applied to two independent asar data sets along ascending 25 scenes and descending 22 scenes orbits acquired between 2003 and 2008 and allowed us to generate deformation velocity maps and displacement time series for the investigated area intercomparison of deformation velocity results from the two asar data sets and their validation against leveling survey measurements were carried out in order to assess accuracy and reliability of the insar observations the intercomparison and validation results demonstrated the potential of elaborate insar processes on local scale areas to monitor and detect a long term residual settlement in such complex reclamation area the insar derived deformation velocity maps showed a fair stability in areas of the two original rocky islands of chek lap kok and lam chau and on most of the buildings at the site due to foundation on piles reaching the granite bedrock whereas a generally moderate 3 7 mm year to strong 10 mm year and spatially variable settlement trend was detected in the majority of reclamation areas of the airport the consistent relationship we found between the observed settlement pattern and the underlying geological conditions suggested that this recoded differential settlement was mainly related to the variations in thickness and soil properties of both the fill materials and the alluvial deposits below the reclamation a geological and geotechnical interpretation of the lithostratigraphy of the alluvial deposits beneath the reclamation implied that the relatively large settlement rate measured up to 2008 was resulted from a still active primary consolidation process

accuracy of topographic maps derived from ers 1 interferometric radar an interferometric radar technique for topographic mapping of surfaces promises a high resolution approach to the generation of digital elevation models the authors present analyses of data collected by the synthetic aperture radar instrument on board the ers 1 satellite on successive orbits use of a single satellite in a nearly repeating orbit is attractive for reducing cost and spaceborne hardware complexity also it permits inference of changes in the surface from the correlation properties of the radar echoes the data have been reduced to correlation maps and digital elevation models the correlation maps show that temporal correlation decreases significantly with time but not necessarily at a constant well defined rate likely depending on environmental factors when correlation among passes remains high however it is possible to form digital elevation models analyses of noise expected in ers 1 interferometric data collected over alaska and the southwestern united states indicate that maps with relative errors less than 5 m rms are possible in some regions however orbit uncertainties imply that tie points are required in order to reduce absolute height errors to a similar magnitude the authors find that about 6 tie points per 40 spl times 40 km scene with 5 m rms or better height accuracy are needed to keep systematic map height errors below 5 m rms the performance of the ers 1 radar system for topographic applications though useful for a variety of regional and local discipline studies may be improved with respect to temporal decorrelation errors and absolute height acuity by modifying the orbit repeat period and incorporating precise orbit determination techniques the resulting implementation will meet many but not all objectives of a global mapping mission

interferometric radar measurement of ocean surface currents we describe a new method of measuring surface currents using an interferometric synthetic aperture radar an airborne implementation has been tested over the san francisco bay near the time of maximum tidal flow resulting in a map of the east west component of the current only the line of sight component of velocity is measured by this technique where the signal to noise ratio was strongest statistical fluctuations of less than 4 cm s 1 were observed for ocean patches of 60 60 m

using advanced insar techniques to monitor landslide deformations induced by tunneling in the northern apennines italy synthetic aperture radar sar interferometry insar is used to make measurements of small surface displacements in different situations including ground settlement landslides and excavations we document the deformation history of four dormant deep seated landslides in the northern apennines of italy that were reactivated by the excavation of a double road tunnel the tunnel is part of a larger infrastructure project that involves the improvement of the a1 highway which connects bologna and florence the excavation of the tunnel under the landslides basal shear surfaces started in 2011 and with the advance of the tunnel front deformation began to occur causing damages to homes and infrastructures the tunnel passes under the small villages of ripoli and santa maria maddalena the deformation slowed down after the tunnel was completed in november 2014 and low surface displacement rates were registered for the period between october 2014 and june 2016 we show the results of an insar analysis designed to measure surface movements between 2003 and 2016 the insar displacements are derived from the envisat cosmo skymed and sentinel 1 datasets and cover the main construction phase of the tunnel 2011 2015 a detailed geological and geomorphological mapping of the slope is developed based on the field evidence and on the spatial pattern of surface deformation provided by our insar analysis together with the map a new conceptual geological model of the slope in tectonically sheared and weathered flysch is presented the satellite insar data show good agreement with available ground based monitoring data that include inclinometer and gps measurements while small differences occur with respect to deformation time series obtained from a ground based insar instrument in particular the insar results for the x band data of cosmo skymed demonstrate the close relationship between the position of the excavation front and the displacement rates of previously dormant landslide deposits conversely the concurrent rainfall does not appear to significantly influence the observed behavior and if any had only a minor influence on the displacement history of the investigated landslides

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

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

algae a fast algebraic estimation of interferogram phase offsets in space varying geometries this paper deals with the estimation of terrain topography from multipass synthetic aperture radar sar interferometry insar focusing on the case where variation of the system geometry within the imaged swath is relevant a typical case is represented by airborne multipass interferometric campaigns where due to the closeness between the radar sensor and the targets the incidence angle sensitivity undergoes a dramatic increase with respect to the spaceborne case resulting in a high spatial variability of the normal baselines the space varying nature of the system geometry gives rise to a major issue in multipass insar analyses in that it prevents from compensating for the presence of interferogram phase offsets by simply phase locking the data stack to a reference point therefore hindering the retrieval of terrain topography to cope with this issue properly we propose a novel approach that exploits the algebraic properties of the problem such an approach allows casting the problem in terms of identification of a null space component for terrain topography after which both topography and the interferogram phase offsets are quickly obtained without exploiting calibration points experimental results are shown based on a p band data set acquired by the experimental sar e sar airborne system operated by the german aerospace center dlr in the framework of the european space agency esa campaign biosar 2008

radarsat 1 and ers insar analysis over southeastern coastal louisiana implications for mapping water level changes beneath swamp forests detailed analysis of c band european remote sensing 1 and 2 ers 1 ers 2 and radarsat 1 interferometric synthetic aperture radar insar imagery was conducted to study water level changes of coastal wetlands of southeastern louisiana radar backscattering and insar coherence suggest that the dominant radar backscattering mechanism for swamp forest and saline marsh is double bounce backscattering implying that insar images can be used to estimate water level changes with unprecedented spatial details on the one hand insar images suggest that water level changes over the study site can be dynamic and spatially heterogeneous and cannot be represented by readings from sparsely distributed gauge stations on the other hand insar phase measurements are disconnected by structures and other barriers and require absolute water level measurements from gauge stations or other sources to convert insar phase values to absolute water level changes

a multidisciplinary study of an active fault crossing urban areas the trecastagni fault at mt etna italy abstract the trecastagni fault is a nnw sse tectonic structure in the densely inhabited southern flank of mt etna characterised by evident morphological scarps and movements of normal and right lateral type that directly affect roads and buildings the fault is affected by continuous dynamics with intermittent accelerations accompanied with shallow seismicity it has an important role in the instability affecting mt etna s south eastern flank and represents part of the southern boundary of the unstable sector the motion of the fault between 2005 and 2011 has been analysed by using a multi disciplinary approach involving terrestrial and satellite ground deformation data active monitoring systems able to investigate the fault in detail are extensometers a levelling network and insar two episodes of acceleration were recorded at the end of 2009 and during 2010 data evidences that the acceleration episodes affected only portions of the fault and that stress may accumulate and be periodically released although both magmatic processes inflation or intrusive episodes and flank dynamics influence the occurrence of the tf acceleration episodes the dragging effect of the overall seaward sliding of the south eastern flank is evident and it causes the subsidence of the hangingwall accumulating stress on the fault that is periodically seismically released

a survey of volcanic deformation on java using alos palsar interferometric time series of the hundreds of volcanic centers throughout the indonesian archipelago few are adequately monitored for pre eruptive activity due to socioeconomic and logistical barriers with the result that volcanic hazards in the region are not well quantified the advent of satellite borne l band synthetic aperture radar provides an opportunity for detection and measurement of volcanic deformation over broad regions in heavily vegetated tropical island arcs we use data from the palsar instrument on the japanese alos satellite to conduct a comprehensive survey of volcanic deformation on the indonesian island of java over a time period of two years 2007 2008 to obtain the most complete temporally continuous record of ground deformation we use a temporally overlapping set of short time interval radar image pairs to produce a deformation time series consistent with previous results from other regions our survey suggests that volcanoes experiencing small eruptions are typically fed by magma bodies too small and or too shallow or deep to produce a recognizable insar signal however we identified a deformation event at lamongan volcano which is likely linked to a magmatic intrusion at several kilometers depth and a second one at slamet volcano at a shallower depth that may have been related to a subsequent eruption this initial test of a broad application of l band data allowed us to better define the satellite imaging criteria required for successful observation as well as developing a useful methodology for monitoring deformation over a wide region

three dimensional surface motion maps estimated from combined interferometric synthetic aperture radar and gps data 1 we provide a technique to efficiently produce high resolution three dimensional surface motion maps by combining information about the motion of the earth s surface from interferometric observations of synthetic aperture radar images and repeated global positioning system gps geodetic measurements unwrapped interferograms showing pixel wise change in range from ground to satellite and sparse values of threedimensional movements are required as input the problem of finding the full threedimensional motion field is separated into two two dimensional problems initially the vertical component of the deformation field and its horizontal component in the look direction of the satellite are found later the look direction component is resolved into north and east components initial values for the motion fields are assigned to each pixel of interferograms from interpolation of available gps observations these values are then updated and optimized by comparison with the interferograms and the gps observations an additional constraint is an assumption of a smoothly varying motion field markov random field based regularization and simulated annealing algorithm are used for the optimization the technique is applied to create surface motion maps for the reykjanes peninsula sw iceland index terms 0933 exploration geophysics remote sensing 0910 exploration geophysics data processing 1206 geodesy and gravity crustal movements interplate 8155 8150 tectonophysics evolution of the earth plate boundary general 3040 8155 tectonophysics evolution of the earth plate motions general keywords remote sensing motion maps deformation data fusion interferometry gps

satellite observation of coal mining subsidence by persistent scatterer analysis ground subsidence persistently occurs in abandoned coal mining areas this paper presents an investigation of ground subsidence measurement using persistent scatterers recorded by space borne synthetic aperture radar sar during the period from november 1992 to october 1998 twenty five jers 1 sar interferometric pairs were obtained and used to measure subsidence in the gaeun coal mining area korea to validate the subsidence estimated by the persistent scatterers sar interferometry ps technique the results were compared with the degree of crack level obtained by a 1997 field survey the study area was divided into five classes based on measured crack levels the line of sight los subsidence rate of each group was estimated by the phase of 135 scatterers selected from the five classes the maximum subsidence was measured by radar as 11 2 cm over 6 yr the mean subsidence rate of one class was found to be 0 5 cm yr where cracks most severely developed the radar estimated subsidence agrees well with the degree of crack level the ps technique is useful for the measurement of ground subsidence in abandoned coal mining areas even in mountainous regions

volumetric characteristics of lava flows from interferometric radar and multispectral satellite data the 1995 fernandina and 1998 cerro azul eruptions in the western galapagos we have used a suite of remotely sensed data numerical lava flow modeling and field observations to determine quantitative characteristics of the 1995 fernandina and 1998 cerro azul eruptions in the western galapagos islands flank lava flow areas volumes instantaneous effusion rates and average effusion rates were all determined for these two eruptions for which only limited syn eruptive field observations are available using data from spot topsar ers 1 and ers 2 we determined that the 1995 fernandina flow covers a subaerial area of 6 5 106 m2 and has a subaerial dense rock equivalent dre volume of 42 106 m3 field observations atsr satellite data and the flowgo numerical model allow us to determine that the effusion rate declined exponentially from a high of 60 200 m3 s 1 during the first few hours to 5 m3 s 1 prior to ceasing after 73 days with a mean effusion rate of 4 16 m3 s 1 integrating the atsr derived exponentially declining effusion rate over the eruption duration produces a total subaerial submarine dre volume of between 27 and 100 106 m3 the range in values being due to differing assumptions about heat loss characteristics only values in the higher part of this range are consistent with the independently derived subaerial volume using spot topsar ers 1 and ers 2 data we determine that the 1998 cerro azul flow is 16 km long covers 16 km2 and has a dre volume of 54 106 m3 flowgo produces at vent velocity and effusion rate values of 11 m s 1 and 600 m3 s 1 respectively the velocity value agrees well with the 12 m s 1 estimated in the field the mean effusion rate total dre volume duration was 7 47 m3 s 1 dike dimensions fissure lengths and pressure gradients along the conduit based on magma chamber depth estimates of 3 5 km produce mean effusion rates for the two eruptions that range over nearly four orders of magnitude the range being due to uncertainty in the magma viscosity dike dimensions and pressure gradient between magma chamber and vent although somewhat consistent with mean effusion rates from other techniques their wide range makes them less useful the exponentially declining effusion rates during both eruptions are consistent with release of elastic strain being the driving mechanism of the eruptions our results provide independent input parameters for previously published theoretical relationships between magma chamber pressurization and eruption rates that constrain chamber volumes and increases in volume prior to eruption as well as time constants of exponential decay during the eruption the results and theoretical relationships combine to indicate that at both volcanoes probably 25 30 of the volumetric increase in the magma chamber erupted as lava onto the surface in both eruptions the lava flow volumes are less than 1 of the magma chamber volume

estimating lava volume by precision combination of multiple baseline spaceborne and airborne interferometric synthetic aperture radar the 1997 eruption of okmok volcano alaska interferometric synthetic aperture radar insar techniques are used to calculate the volume of extrusion at okmok volcano alaska by constructing precise digital elevation models dems that represent volcano topography before and after the 1997 eruption the posteruption dem is generated using airborne topographic synthetic aperture radar topsar data where a three dimensional affine transformation is used to account for the misalignments between different dem patches the preeruption dem is produced using repeat pass european remote sensing satellite data multiple interferograms are combined to reduce errors due to atmospheric variations and deformation rates are estimated independently and removed from the interferograms used for dem generation the extrusive flow volume associated with the 1997 eruption of okmok volcano is 0 154 spl plusmn 0 025 km sup 3 the thickest portion is approximately 50 m although field measurements of the flow margin s height do not exceed 20 m the in situ measurements at lava edges are not representative of the total thickness and precise dem data are absolutely essential to calculate eruption volume based on lava thickness estimations this study is an example that demonstrates how insar will play a significant role in studying volcanoes in remote areas

interferometric estimation of three dimensional ice flow using ascending and descending passes satellite radar interferometry sri provides an important new tool for determining ice flow velocity interferometric measurements made from a single track direction are sensitive only to a single component of the three component velocity vector observations from along three different track directions would allow the full velocity vector to be determined a north south looking synthetic aperture radar sar could provide these observations over large portions of the globe but not over large areas of the polar ice sheets the authors develop and demonstrate a technique that allows the three component velocity vector to be estimated from data acquired along two track directions ascending and descending under a surface parallel flow assumption this technique requires that there are accurate estimates of the surface slope which are also determined interferometrically to demonstrate the technique the authors estimate the three component velocity field for the ryder glacier greenland their results are promising although they do not have yet ground truth data with which to determine the accuracy of their estimates

analysis of ground based sar data with diverse temporal baselines in this paper the algorithms developed for satellite synthetic aperture radar sar interferometry were adapted to the ground based sar gb sar configuration and used for detecting the displacements of an alpine landslide which have occurred over many years indeed gb sar interferometry is based on the same principles as satellite sar techniques but benefits from the gb sar s versatility and capability of gathering many images per day in monitoring applications of landslides moving only few centimeters per year as the case here reported the gb sar sensor is installed at repeated intervals several months apart over the observation period although the revisiting time is very similar to the satellite one for each survey lasting two or three days more than ten images are available they are analyzed separately and in combination with images from other surveys for coherent pixel selection interferograms are formed by cross combining images from different surveys finally the evolution of the deformation across the surveys is retrieved in a least square sense without any assumptions on its regularity the used gb sar technique is described in detail in this paper and the results obtained with regard to a landslide in the italian alps that has been monitored over a period of about three years are discussed

spatial analysis of surface deformation distribution detected by persistent scatterer interferometry in lanzhou region china persistent scatterer synthetic aperture radar interferometry ps insar is a remote sensing method that can be used to detect surface deformation which is an indicator of potential geohazards by capturing such deformations over time it is possible to obtain valuable information regarding geohazards such as landslides this study focused on the use of ps insar to investigate the distribution and causes of surface deformation in the lanzhou region of gansu province in china between 2003 and 2010 41 advanced synthetic aperture radar images were captured by the envisat satellite and analyzed using ps insar and the correlation between the observed surface deformation and topographic geologic and anthropogenic factors was derived based on a geographic information system platform it was found that the largest number and highest density of surface deformations occurred at elevations of 1486 1686 m it was also established that slope ranges of 25 30 and 35 40 are threshold values at which surface deformation changes abruptly and that slopes with north and northwest aspects are most prone to surface deformation the lithologies most susceptible to surface deformation are clay sandy soil and loess the normalized difference vegetation index indicated that surface deformation occurred most often in areas with sparse vegetation anthropogenic activities e g construction and wastewater discharge could be inferred as causal mechanisms of surface deformation comparison of the distributions of geohazards and surface deformation showed considerable consistency which proves surface deformation can induce geohazards these results could help governments improve urban planning and geohazard mitigation

present day strain distribution across a segment of the central bend of the north anatolian fault zone from a persistent scatterers insar analysis of the ers and envisat archives

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

studies of multibaseline spaceborne interferometric synthetic aperture radars the authors have utilized a set of seasat synthetic aperture radar sar data that were obtained in nearly repeat ground track orbits to demonstrate the performance of spaceborne interferometric sar insar systems an assessment of the topography measurement capability is presented a phase measurement error model is described and compared with the data obtained at various baseline separations and signal to noise ratios finally the implications of these results on future spaceborne insar design are discussed

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

repeat pass sar interferometry for land cover classification a methodology using sentinel 1 short time series abstract in this paper we explore the potential of repeat pass interferometric sar insar for land cover classification purposes we introduce a novel approach for the generation of large scale thematic maps based on the use of multi temporal data acquired over short observation intervals short time series a larger interferometric coherence loss is expected with the increasing time difference between two interferometric acquisitions this phenomenon is normally indicated as temporal decorrelation whose amount differs depending on the type of imaged target on ground the basic idea is therefore to accurately model the evolution in time of the temporal decorrelation and use the estimated parameters together with backscatter as input features for the random forest machine learning classification algorithm the work has been carried out on the case study of land cover mapping over central europe considering sentinel 1 c band interferometric stacks acquired over a time span of about one month three different land cover classes have been considered artificial surfaces as e g urban areas forests and non forested areas as the ensemble of low vegetation bare soil and agricultural areas the results show a level of agreement above 91 when compared to the corine land cover map product of 2012 which has been used as external reference for both training and testing of the classification algorithm

sir c x sar multifrequency multipass interferometry a new tool for geological interpretation radar remote sensing is a tool of increasing importance in the study of volcanic sites synthetic aperture radar sar is a high resolution imaging tool used to survey areas which are not practical or safe to be directly inspected with the introduction of the across track sar interferometry ifsar technique digital elevation models dem can be produced the usefulness of such interferometric products depends on the ability to extract information that can be used for geological interpretation we analyzed the shuttle imaging radar c sir c x sar multifrequency multipass interferometry mission over mount etna sicily and we performed a supervised geological interpretation of the coherence maps and a fractal based analysis of the ifsar dems the first permits us to recognize different volcanic terrain and to distinguish between vegetated and unvegetated areas while the second allows us to validate the ifsar dems and to detect large scale geological features this latter analysis performed over the photogrammetric dem enabled us to recognize artifacts caused by digitizing and resampling obviously ifsar dems are not affected by these problems as a consequence ifsar products are a valuable aid in geological interpretation

remote sensing of ocean currents a method of remotely measuring near surface ocean currents with a synthetic aperture radar sar is described the apparatus consists of a single sar transmitter and two receiving antennas the phase difference between sar image scenes obtained from the antennas forms an interferogram that is directly proportional to the surface current the first field test of this technique against conventional measurements gives estimates of mean currents accurate to order 20 percent that is root mean square errors of 5 to 10 centimeters per second in mean flows of 27 to 56 centimeters per second if the full potential of the method could be realized with spacecraft then it might be possible to routinely monitor the surface currents of the world s oceans

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

ground based radar interferometry for landslides monitoring atmospheric and instrumental decorrelation sources on experimental data the application of ground based radar interferometry for landslide monitoring is analyzed a case study based on an experimental campaign carried out in italy during 2002 is discussed interferometric data obtained from coherent synthetic aperture radar sar images acquired by means of c band ground based equipment are analyzed the campaign was aimed at retrieving potential terrain movements of a small landslide observed hundreds of meters away critical aspects related to spatial and temporal decorrelation are discussed the use of optical photogrammetry as a technique for evaluating mechanical stability and correcting geometric distortion is presented results also confirmed that the application of ground based radar interferometry can be attractive and effective if the acquired sar images maintain an adequate coherence on different dates

the topsar interferometric radar topographic mapping instrument the authors have augmented the nasa dc 8 airsar instrument with a pair of c band antennas displaced across track to form an interferometer sensitive to topographic variations of the earth s surface during the 1991 dc 8 flight campaign data were acquired over several sites in the us and europe and topographic maps were produced from several of these flight lines analysis of the results indicate that statistical errors are in the 2 4 m range while systematic effects due to aircraft motion are in the 10 20 m range the initial results from development of a second generation processor show that aircraft motion compensation algorithms reduce the systematic variations to 2 m while the statistical errors are reduced to 2 3 m

sar monitoring of progressive and seasonal ground deformation using the permanent scatterers technique spaceborne differential radar interferometry has proven a remarkable potential for mapping ground deformation phenomena e g urban subsidence volcano dynamics coseismic and postseismic displacements along faults as well as slope instability however a full operational capability has not been achieved yet due to atmospheric disturbances and phase decorrelation phenomena these drawbacks can often be at least partially overcome by carrying out measurements on a subset of image pixels corresponding to natural or artificial stable reflectors permanent scatterers ps and exploiting long temporal series of interferometric data this approach allows one to push the measurement precision very close to its theoretical limit in the order of spl sim 1 mm for c band european remote sensing ers like sensors in this paper the detection of both time uniform and seasonal deformation phenomena is addressed and a first assessment of the precision achievable by means of the ps technique is discussed results highlighting deformation phenomena occurring in two test sites in california are reported fremont in the southern bay area and san jose in the santa clara valley