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

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

results for aseismic creep on the hayward fault using polarization persistent scatterer insar abstract we present new results for shallow aseismic creep on the hayward fault in california using a new dinsar technique this method not only provides for the first time the ability to map the displacement field on both sides of the fault it does so over a much shorter time period than earlier results the results provide a good match in the near field to both the regional continuous gps velocities and data from an alinement network that measures long term creep along the fault the average slip rate for the northern segment of the hayward fault is 4 4 mm yr between 2008 and 2011 slightly less than that estimated for longer time periods suggesting that the slip rate may not be constant if the slip rate along the fault is variable on the decadal or longer scale current estimates of its earthquake potential and the associated hazard associated with the slip rate deficit may need to be revised from previous estimates we demonstrate the potential impact of this method to better define the spatial and temporal complexity of aseismic slip and estimate the accumulated elastic strain along one of the most significant sources of seismic hazard in the san francisco bay area

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

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

monitoring landslides and tectonic motions with the permanent scatterers technique spaceborne differential synthetic aperture radar interferometry dinsar has already proven its potential for mapping ground deformation phenomena e g volcano dynamics however atmospheric disturbances as well as phase decorrelation have prevented hitherto this technique from achieving full operational capability these drawbacks are overcome by carrying out measurements on a subset of image pixels corresponding to pointwise stable reflectors permanent scatterers ps and exploiting long temporal series of interferometric data results obtained by processing 55 images acquired by the european space agency esa ers sar sensors over southern california show that the ps approach pushes measurement accuracy very close to its theoretical limit about 1 mm allowing the description of millimetric deformation phenomena occurring in a complex fault system a comparison with corresponding displacement time series relative to permanent gps stations of the southern california integrated gps network scign is carried out moreover the pixel by pixel character of the ps analysis allows the exploitation of individual phase stable radar targets in low coherence areas this makes spaceborne interferometric measurements possible in vegetated areas as long as a sufficient spatial density of individual isolated man made structures or exposed rocks is available the evolution of the ancona landslide central italy was analysed by processing 61 ers images acquired in the time span between june 1992 and december 2000 the results have been compared with deformation values detected during optical levelling campaigns ordered by the municipality of ancona the characteristics of ps gps and optical levelling surveying are to some extent complementary a synergistic use of the three techniques could strongly enhance quality and reliability of ground deformation monitoring d 2002 elsevier science b v all rights reserved

a volcano bursting at the seams inflation faulting and eruption at sierra negra volcano galapagos the results of geodetic monitoring since 2002 at sierra negra volcano in the galapagos islands show that the filling and pressurization of an 2 km deep sill eventually led to an eruption that began on 22 october 2005 continuous global positioning system cgps monitoring measured 2 m of accelerating inflation leading up to the eruption and contributed to nearly 5 m of total uplift since 1992 the largest precursory inflation ever recorded at a basaltic caldera this extraordinary uplift was accommodated in part by repeated trapdoor faulting and coseismic cgps data provide strong constraints for improved deformation models these results highlight the feedbacks between inflation faulting and eruption at a basaltic volcano and demonstrate that faulting above an intruding magma body can relieve accumulated strain and effectively postpone eruption

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

slip rate of the calico fault implications for geologic versus geodetic rate discrepancy in the eastern california shear zone 1 long term 10 5 years fault slip rates test the scale of discrepancy between infrequent paleoseismicity and relatively rapid geodetic rates of dextral shear in the eastern california shear zone ecsz the calico fault is one of a family of dextral faults that traverse the mojave desert portion of the ecsz its slip rate is determined from matching and dating incised pleistocene alluvial fan deposits and surfaces displaced by fault slip a high resolution topographic base acquired via airborne laser swath mapping aids in identification and mapping of deformed geomorphic features the oldest geomorphically preserved alluvial fan unit b is displaced 900 200 m from its source at sheep springs wash in the northern rodman mountains this fan deposit contains the first preserved occurrence of basalt clasts derived from the pipkin lava field and overlies quaternary conglomerate deposits lacking these clasts the 40 ar 39 ar dating of two flows from this field yields consistent ages of 770 40 ka and 735 9 ka an age of 650 100 ka is assigned to this fan deposit based on these ages and on the oldest cosmogenic 3 he exposure date of 653 20 ka on a basalt boulder from the surface of unit b this assigned age and offset together yield a mid pleistocene to present average slip rate of 1 4 0 4 mm yr ayounger fan surface unit k records 100 10 m of dextral displacement and preserves original depositional morphology of its surface granitic boulders and pavement samples from this surface yield an average age of 56 4 7 7 ka after taking into account minimal cosmogenic inheritance of granitic clasts the displaced and dated k fans yield a slip rate of 1 8 0 3 mm yr distributed deformation of the region surrounding the fault trace if active could increase the overall displacement rate to 2 1 0 5 mm yr acceleration of slip rate from an average of 1 4 mm yr prior to 50 ka to 1 8 mm yr since 50 ka is possible though a single time averaged slip rate of 1 6 0 2 mm yr satisfies the data these rates are faster than any other paleoseismic or long term slip rate yet determined for other dextral faults in the mojave desert and imply that fault slip rates and earthquake productivity are heterogeneous across this portion of the ecsz total displacement across the calico fault diminishes northward as shear is distributed into folding and sinistral faults in the calico mountains this pattern is consistent with an approximately threefold drop in geologic slip rate as the calico fault steps over onto the blackwater fault and demonstrates the significance of fault interaction for understanding the pattern of present day strain accumulation in the ecsz

persistent scatterer selection incorporating polarimetric sar interferograms based on maximum likelihood theory persistent scatterer ps interferometry analysis has been performed using single polarimetric synthetic aperture radar sar interferograms but newer sar satellites enable the use of polarimetric data for such analyses in this paper to analyze polarimetric sar interferograms we proposed the maximum likelihood method at the ps selection stage with the proposed method interferograms in a certain polarimetric component exhibiting high coherence contribute to the estimation of surface displacements whereas noisy interferograms of another polarimetric component are less used the proposed method was examined by analyzing full and dual polarimetric interferograms using data obtained from alos palsar images in full polarimetric acquisition mode the results showed an increase in the number of coherent pixels used to map surface displacements and that number increased particularly in the analysis of full polarimetric data for example in the case of full polarimetric interferograms in linear hv basis the number increased by a factor of 1 8 3 8 compared with those of single polarimetric interferograms and by a factor of 1 14 compared with a simple integration of the results of single polarimetric data our method increases the accuracy of the detection of the detailed spatial displacement pattern of a displacement phenomenon

the volcanic history of volcan alcedo galapagos archipelago a case study of rhyolitic oceanic volcanism volcan alcedo is one of the seven western galapagos shields and is the only active galapagos volcano known to have erupted rhyolite as well as basalt the volcano stands 4 km above the sea floor and has a subaerial volume of 200 km3 nearly all of which is basalt as volcan alcedo grew it built an elongate domal shield which was partly truncated during repeated caldera collapse and partial filling episodes an outward dipping sequence of basalt flows at least 250 m thick forms the steepest to 33 flanks of the volcano and is not tilted thus a constructional origin for the steep upper flanks is favored about 1 km3 of rhyolite erupted late in the volcano s history from at least three vents and in 2 5 episodes the most explosive of these produced a tephra blanket that covers the eastern half of the volcano homogeneous rhyolitic pumice is overlain by dacite rhyolite commingled pumice with no stratigraphic break the tephra is notable for its low density and coarse grain size the calculated height of the eruption plume is 23 30 km and the intensity is estimated to have been 1 2x108 kg s rhyolitic lavas vented from the floor of the caldera and from fissures along the rim overlie the tephra of the plinian phase the age of the rhyolitic eruptions is 120 ka on the basis of k ar ages between ten and 20 basaltic lava flows are younger than the rhyolites recent faulting resulted in a moat around part of the caldera floor alcedo most resently erupted sometime between 1946 and 1960 from its southern flank alcedo maintains an active transient hydrothermal system acoustic and seismic activity in 1991 is attributed to the disruption of the hydrothermal system by a regional scale earthquake

spatio temporal evolution of aseismic slip along the haiyuan fault china implications for fault frictional properties article history we use 20 years of synthetic aperture radar acquisitions by the ers and envisat satellites to investigate the spatial and temporal variations of strain rates along the 35 km long creeping section of the haiyuan fault at the north eastern boundary of the tibetan plateau we then use the derived displacements to infer the fault s frictional properties and discuss the relationship between creep and the seismic behavior of the fault located in between a millennial seismic gap and the 1920 m8 surface rupture trace this section has an average creep rate of 5 1m m yr about the interseismic loading rate the comparison of average surface velocity profiles derived from sar interferometry across the creeping section reveals a creep rate increase and or a creep migration to shallower depth between the 1990s and the 2000s we apply a smoothed time series analysis scheme on envisat insar data to investigate the creep rate variations during the 2004 2009 time period our analysis reveals that the creep rate accelerated in 2007 although data resolution does not allow to better constrain the onset of creep acceleration and its amplitude both decadal and short term transient behaviors are coeval with the largest earthquakes m 4 5 along the fault segment in recent years from the precise mapping of the surface fault trace we use the fault strike variations and the mohr circle construction to compute the along strike distribution of the friction coefficient along the creeping segment and compare it with the observed distribution of the creep rate we find that the creep rate scales logarithmically with the friction coefficient in agreement with the rate and state friction law in a rate strengthening regime the estimated value of log v 2 10 3 indicates that the earthquakes occurring along the creeping section cannot be the cause for a significant change in the overall segment s creep rate and that the recorded micro seismicity is most likely creep driven finally given the size and frictional properties of the creeping section we estimate based on previous models of dynamic rupture simulations a 0 20 probability for a rupture to break through this section together with the geometrical configuration of the haiyuan fault these results suggest that the creeping segment may act as a persistent barrier to earthquake propagation

nonlinear subsidence rate estimation using permanent scatterers in differential sar interferometry discrete and temporarily stable natural reflectors or permanent scatterers ps can be identified from long temporal series of interferometric sar images even with baselines larger than the so called critical baseline this subset of image pixels can be exploited successfully for high accuracy differential measurements the authors discuss the use of ps in urban areas like pomona ca showing subsidence and absidence effects a new approach to the estimation of the atmospheric phase contributions and the local displacement field is proposed based on simple statistical assumptions new solutions are presented in order to cope with nonlinear motion of the targets

slope deformation prior to zhouqu china landslide from insar time series analysis abstract a major landslide in zhouqu china occurred on august 8 2010 and caused widespread damage and over 1700 casualties we study the deformation of the slopes over a time period of about three years prior to the landslide by an enhanced stamps sb technique with 16 ascending alos palsar images in particular the orbit error and stratified troposphere that were not well dealt with in the original stamps sb method have been satisfactorily corrected by a novel phase ramp correction method the deformation in four regions of the study area has been retrieved with a maximum of up to 70 mm yr in the luojiayu sanyanyu valley the slopes where the 2010 giant landslide occurred have been found to be quite unstable before the event deformation exceeding 30 mm yr has been detected in the suoertou slope which is a well known place for an ancient fault zone landslide fast movement larger than 40 mm yr is observed in the xieliupo slope which poses threats of landslide dam and dammed lake to the pai lung river together with another slope deformation detected in the opposite slope in the nanshanqiaotou slope the detected 30 mm yr deformation can be viewed as the prelude of the large landslide occurred in october 2010 more important it is found that the slope deformation time series has strong correlation with the precipitation in the area as well as with the devastating wenchuan earthquake that occurred in may 2008 whose epicenter is about 300 km away from zhouqu

extent and distribution of aseismic slip on the ismetpasa segment of the north anatolian fault turkey from persistent scatterer insar we use the persistent scatterer insar psi technique with elastic dislocation models and geology along the creeping section of the north anatolian fault naf at ismetpasa to map and deduce the velocity field and the aseismic slip distribution revealing the spatiotemporal nature of the creep helped us associate the creep with potential lithological controls hence providing a new perspective to better understand the underlying causes and mechanisms the psi analysis of envisat asar images between 2003 and 2010 reveals a clear picture of surface creep along the fault and a new interseismic velocity field transitioning gradually between the creeping and the locked fault sections the creep rate is found to fluctuate along a 100 km long section of the fault in a manner similar to that along the hayward fault reaching a maximum of 20 2 mm yr close to the far field plate velocity 25 1 5 mm yr at ismetpasa it is in the range of 8 2 mm yr consistent with the previous geodetic observations the creeping section appears to extend 30 km further east than those previously reported modeling of the psi data reveals a heterogeneous creep distribution at depth with two main patches confined mostly to the uppermost 5 km portion of the seismogenic crust releasing annually 6 2 1016 nm mw 5 1 geodetic moment our analysis combined with previous studies suggests that creep might have commenced as postseismic deformation following the 1944 earthquake and has evolved to stable fault creep with time there is a correlation between aseismic surface creep and the geology along the fault as it is in major part associated to rocks with low frictional strength such as the andesitic basaltic limestone and serpentine bodies within the fault zone

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

clay alteration associated with proterozoic unconformity type uranium deposits in the east alligator rivers uranium field northern territory australia clay minerals associated with the unconformity type uranium deposits of the east alligator rivers uranium field have been used to determine the spatial distribution of hydrothermal alteration and the conditions of uranium deposition within the altered basement underlying the kombolgie unconformity alteration develops a similar pattern at regional and smaller scales with a close relationship between the degree of alteration and the amount of structural discontinuities observed on both sides of the unconformity e g faults fractures breccias these discontinuities were mechanically active during the hydrothermal activity the hydrothermal clay minerals partly to totally replace diagenetic dickite and illite in the kombolgie sandstones and metamorphic phengite and chlorite in the basement rocks the time space alteration sequence established in this study can be summarized as follows 1 early crystallization of illite illite smectite i s mixed layer minerals lree sr bearing aluminum phosphate sulfates aps in sandstones above the unconformity illite i s mixed layer minerals sudoite aps on both sides of the unconformity and in fault gouges and illite i s mixed layer minerals chlorite apatite deeper in the basement and 2 late precipitation of chlorite in the open fracture network mainly centered below the unconformity the main stage of uranium deposition was associated with chloritization in the basement rocks smaller particle size lath shaped or flaky morphology common interstratification with expandable layers lower crystallinity and mg rich chemical compositions can be used to distinguish the hydrothermal clays from the other diagenetic and metamorphic illite and or chlorite hydrothermal illite can be distinguished from diagenetic and metamorphic illite phengite by its poor crystallinity along the c axis interstratification with minor amounts of smectite layers and a 1m polytype in which trans vacant octahedral sites predominate 1 mt chemically the hydrothermal illite differs from diagenetic illite by a lower interlayer charge and a higher mg content the hydrothermal chlorite is distinguished from the metamorphic chlorite by its smaller particle size spherulitic habit poor crystallinity along the c axis and common association with corrensite and or chlorite corrensite mixed layers most of the hydrothermal chlorite is mg rich and has a structural formula close to that of clinochlore xfe 0 20 near the uranium deposits the spherules of hydrothermal chlorite are chemically zoned from xfe 0 10 to xfe 0 40 which is interpreted as the result of a change in the oxidation state of the hydrothermal solution during the chlorite crystallization the space time alteration sequence established for clay minerals and the observed transition of aps to apatite are interpreted as the result of an increasing degree of interaction of the basement rocks with infiltrating acidic and oxidizing sub basinal brines in turn these fluids tend to be neutralized and reduced by their ongoing interaction with ferrous iron bearing phyllosilicates fe chlorite and biotite and iron sulfides of metamorphic origin the ore deposits are surrounded by zones in which the degree of fluid rock interaction was very high and chloritization is most abundant the octahedral mg content of the associated hydrothermal illite from the sandstone can be used as a guide to indicate the possible presence of uranium orebodies in the basement rocks tens to hundreds of meters below the crystal structures of the hydrothermal illite and chlorite suggest that these minerals crystallized at temperatures approximatively 30 to 50 c lower than those expected at the peak diagenesis of the kombolgie sandstones near the unconformity

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 new method for measuring deformation on volcanoes and other natural terrains using insar persistent scatterers 1 we present here a new insar persistent scatterer ps method for analyzing episodic crustal deformation in non urban environments with application to volcanic settings our method for identifying ps pixels in a series of interferograms is based primarily on phase characteristics and finds low amplitude pixels with phase stability that are not identified by the existing amplitude based algorithm our method also uses the spatial correlation of the phases rather than a well defined phase history so that we can observe temporally variable processes e g volcanic deformation the algorithm involves removing the residual topographic component of flattened interferogram phase for each ps then unwrapping the ps phases both spatially and temporally our method finds scatterers with stable phase characteristics independent of amplitudes associated with man made objects and is applicable to areas where conventional insar fails due to complete decorrelation of the majority of scatterers yet a few stable scatterers are present

constructing accurate maps of atmospheric water vapor by combining interferometric synthetic aperture radar and gnss observations over the past 20years repeat pass spaceborne interferometric synthetic aperture radar insar has been widely used as a geodetic technique to generate maps of the earth s topography and to measure the earth s surface deformation in this paper we present a new approach to exploit microwave data from insar particularly persistent scatterer insar psi and global navigation satellite systems gnss to derive maps of the absolute water vapor content in the earth s atmosphere atmospheric water vapor results in a phase shift in the insar interferogram which if successfully separated from other phase components provides valuable information about its distribution psi produces precipitable water vapor pwv difference maps of a high spatial density which can be inverted using the least squares method to retrieve pwv maps at each sar acquisition time these maps do not contain the absolute total pwv along the signal path but only a part of it the components eliminated by forming interferograms or phase filtering during psi data processing are reconstructed using gnss phase observations the approach is applied to build maps of absolute pwv by combining data from insar and gnss over the region of upper rhine graben in germany and france for validation we compared the derived pwv maps with pwv maps measured by the optical sensor medium resolution imaging spectrometer the results show strong spatial correlation with values of uncertainty of less than 1 5mm continuous grids of pwv are then produced by applying the kriging geostatistical interpolation technique that exploits the spatial correlations between the pwv observations

space geodetic observations and models of postseismic deformation due to the 2005 m7 6 kashmir pakistan earthquake we use the l band advanced land observing satellite alos and c band envisat interferometric synthetic aperture data and campaign gps observations to study the postseismic deformation due to the 2005 magnitude 7 6 kashmir pakistan earthquake that occurred in the northwestern himalaya envisat data are available from both the descending and ascending orbits and span a time period of 4 5 years immediately following the earthquake 2005 2010 with nearly monthly acquisitions however the envisat data are highly decorrelated due to high topography and snow cover alos data are available from the ascending orbit and span a time period of 2 5 years between 2007 and 2009 over which they remain reasonably well correlated we derive the mean line of sight los postseismic velocity maps in the epicentral area of the kashmir earthquake using persistent scatterer method for envisat data and selective stacking for alos data los velocities from all data sets indicate an uplift decrease in radar range primarily in the hanging wall of the earthquake rupture over the entire period of synthetic aperture radar observations 2005 2010 models of poroelastic relaxation predict uplift of both the footwall and the hanging wall while models of viscoelastic relaxation below the brittle ductile transition predict subsidence increase in radar range in both the footwall and the hanging wall therefore the observed pattern of surface velocities indicates that the early several years of postseismic deformation were dominated by afterslip on the fault plane possibly with a minor contribution from poroelastic rebound kinematic inversions of interferometric synthetic aperture radar and gps data confirm that the observed deformation is consistent with afterslip primarily downdip of the seismic asperity to place constraints on the effective viscosity of the ductile substrate in the study area we subtract the surface deformation predicted by stress driven afterslip model from the mean los velocities and compare the residuals to models of viscoelastic relaxation for a range of assumed viscosities we show that in order to prevent surface subsidence the effective viscosity has to be greater than 1019 pa s

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

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

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

intrusion triggering of the 2010 eyjafjallajokull explosive eruption the ash cloud that brought chaos to european air traffic in april this year was the result of emissions from an icelandic volcano that had been intermittently active for about 18 years a combination of detailed space based geodetic measurements and seismic monitoring of the eyjafjallajkull volcano in the run up to the ash producing explosive summit eruption reveals an unusual deformation pattern that may be attributed to its off rift setting with relatively cool subsurface structure and limited magma at shallow depth as to the predictability of such a dramatic reawakening the immediate precursors to the initial eruption of the volcano in 2010 were subtle and difficult to detect but the clear signs of volcanic unrest during the weeks months and years preceding it may provide better clues to the catastrophic explosion

present day surface deformation and tectonic insights of the extensional ilan plain ne taiwan abstract taiwan s mountain belt is an ideal location to address major questions regarding mechanisms of lithospheric deformation in convergent settings mountain building processes from oceanic subduction to continental subduction and post orogenic extension in the northeast of this belt the ilan plain is a triangular deltaic plain characterized by a flat topography close to the sea level and surrounded by the high mountains of the hsuehshan range to the northwest and the central range to the southeast its eastern coast faces the western tip of the okinawa trough the back arc basin of the ryukyu subduction zone in this study we analyzed the present day surface deformation of the ilan plain aiming at deciphering its relationships with basement faults and the regional geodynamic setting our approach is mainly based on surface vertical displacements revealed by persistent scatterer interferometry synthetic aperture radar psi which indicate that there is an area of active subsidence 18 mm yr located in the southern part of the plain in probable connection with active basement faults and in agreement with previous geodetic measurements and existing geophysical data our psi results also suggest that the subsidence occurring in the ilan plain has moved from north to south during quaternary in relation with extrusion of the belt due to the westward propagation of the okinawa trough through the taiwan mountains

widespread uplift and trapdoor faulting on galapagos volcanoes observed with radar interferometry volcanic uplift caused by the accumulation of magma in subsurface reservoirs is a common precursor to eruptions1 2 but for some volcanoes uplift of metres or more has not yet led to an eruption3 here we present displacement maps of volcanoes in the galapagos islands constructed using satellite radar interferometry that might help explain this dichotomy we show that all but one of the seven volcanoes on the islands of isabela and fernandina deformed during 1992 99 cerro azul and fernandina erupted4 5 6 during the observation period and show evidence of inflation co eruptive deflation and shallow dyke intrusion in contrast the largest volcano sierra negra has not erupted yet exhibits spatially and temporally variable deformation with a maximum uplift of 2 7 m between 1992 and 1999 which can be modelled by a shallow inflating sill inflation during 1997 98 however was accompanied by trapdoor faulting on a steeply dipping fracture system within the caldera repeated trapdoor faulting over geological time has formed an arcuate intra caldera ridge within sierra negra and may have acted to relax stresses above the magma chamber inhibiting summit eruptions similar processes may help explain large uplift unaccompanied by eruptive activity at other volcanoes

mapping surface deformation and thermal dilation of arch bridges by structure driven multi temporal dinsar analysis abstract arch bridges are important transportation infrastructures widely distributed in china but they are prone to structural defects due to aging without routine inspection and maintenance therefore structural health monitoring shm of these bridges is urgently needed by civil engineers to effectively reduce the risk of bridge damage or collapse on public safety an essential method for shm the modern differential synthetic aperture radar interferometry dinsar technique can detect subtle deformation of bridges at relatively low costs nevertheless identifying dense point like targets pts on such partially coherent arch bridges in sar image is more difficult than that for other man made objects owing to their complex structures and backscattering behaviors furthermore the complex mechanical properties of arch bridges due to the varying arch beam interactions make it hard to separate the surface deformation and thermal dilation accurately and the lack of specific structural knowledge that can help to understand the deformation evolution process limits the global structural risk assessment aiming at these problems we developed a structure driven multi temporal dinsar approach for arch bridge specific shm by introducing three structure driven steps i e backscattering geometrical interpretation linear thermal dilation estimation and validation and deformation feature points dfps based risk assessment into the traditional dinsar method the reliability of pts identification thermal dilation separation and structural risk assessment for arch bridges are significantly improved the effectiveness of our approach was fairly presented by two case studies of the rainbow and lupu bridges and the experimental results were verified by leveling benchmark validation cross sensor comparison as well as structural reliability assessment our results revealed that arch bridges exhibit a similar pattern of pts distribution that is dense around piers and sparse on the spans as well as a symmetrical progressive pattern of surface deformation with the subsidence increasing from piers and reaching a peak at the central spans in contrast magnitudes and mechanisms of thermal dilation are different and highly dependent on the materials and structural characteristics of specific bridges

constraints on magma chamber geometry at sierra negra volcano galapagos islands based on insar observations abstract we investigate the problem of estimating magma chamber geometry using insar observations of sierra negra volcano galapagos ascending and descending interferograms are combined to determine vertical and one horizontal component of displacement the ratio of maximum horizontal to vertical displacement suggests a sill like source spherical or stock like bodies are inconsistent with the data we estimate the geometry of the sill assuming a horizontal uniformly pressurized crack with unknown periphery and depth the sill is discretized into small elements that are either open and are subjected to the pressure boundary condition or remain closed we find the best fitting sill to be located beneath sierra negra s inner caldera at a depth of about 2 km using boundary element calculations we show that any magma chamber with a flat top coincident with the sill model fits the data equally well the data are insensitive to the sides and bottom of the magma chamber

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

postglacial crustal doming stresses and fracture formation with application to norway abstract postglacial doming of fennoscandia is estimated to have reached a maximum uplift value of 850 m vertical uplift of this magnitude generates stresses that affect the tectonic activity in the domed area using a simple model of a circular elastic plate subject to deflection it is shown that the maximum tensile stresses generated by this uplift occur in the centre of the dome and at the surface reach a numerical value of nearly 30 mpa this tensile stress is an order of magnitude greater than the typical in situ tensile strength of the uppermost part of the crust so that tension fractures are easily generated by this stress tension fractures can under certain conditions reach crustal depths of several hundred metres but if they propagate to greater depths they change into normal faults the tensile stresses at the surface decrease in magnitude with distance from the centre of the dome and become compressive in the marginal parts of the uplifted crustal plate at the surface of these parts the maximum shear stress exceeds 10 mpa because the inferred driving stresses stress drops in earthquakes are commonly only several mpa it follows that the driving shear stress in these marginal parts is large enough to initiate or reactivate seismogenic faults these model results are in broad agreement with data on the current seismotectonics of fennoscandia the formation and reactivation of tensile and shear fractures in fennoscandia as a result of postglacial uplift is likely to increase the hydraulic conductivity of the solid rocks that constitute the uppermost part of the crust this conclusion is supported by reported observations which indicate that the production of groundwater in wells in many areas in norway varies positively with the maximum postglacial uplift

merging gps and atmospherically corrected insar data to map 3 d terrain displacement velocity a method to derive accurate spatially dense maps of 3 d terrain displacement velocity is presented it is based on the merging of terrain displacement velocities estimated by time series of interferometric synthetic aperture radar insar data acquired along ascending and descending orbits and repeated gps measurements the method uses selected persistent scatterers pss and gps measurements of the horizontal velocity an important step of the proposed method is the mitigation of the impact of atmospheric phase delay in insar data it is shown that accurate vertical velocities at ps locations can be retrieved if smooth horizontal velocity variations can be assumed furthermore the mitigation of atmospheric effects reduces the spatial dispersion of vertical velocity estimates resulting in a more spatially regular 3 d velocity map the proposed methodology is applied to the case study of azores islands characterized by important tectonic phenomena

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

fault creep along the southern san andreas from interferometric synthetic aperture radar permanent scatterers and stacking 1 interferometric synthetic aperture radar insar provides a practical means of mapping creep along major strike slip faults the small amplitude of the creep signal 10 mm yr combined with its short wavelength makes it difficult to extract from long time span interferograms especially in agricultural or heavily vegetated areas we utilize two approaches to extract the fault creep signal from 37 ers sar images along the southern san andreas fault first amplitude stacking is utilized to identify permanent scatterers which are then used to weight the interferogram prior to spatial filtering this weighting improves correlation and also provides a mask for poorly correlated areas second the unwrapped phase is stacked to reduce tropospheric and other short wavelength noise this combined processing enables us to recover the near field 200 m slip signal across the fault due to shallow creep displacement maps from 60 interferograms reveal a diffuse secular strain buildup punctuated by localized interseismic creep of 4 6 mm yr line of sight los 12 18 mm yr horizontal with the exception of durmid hill this entire segment of the southern san andreas experienced right lateral triggered slip of up to 10 cm during the 3 5 year period spanning the 1992 landers earthquake the deformation change following the 1999 hector mine earthquake was much smaller 1 cm and broader than for the landers event profiles across the fault during the interseismic phase show peak to trough amplitude ranging from 15 to 25 mm yr horizontal component and the minimum misfit models show a range of creeping locking depth values that fit the data

generation of highly accurate dems over flat areas by means of dual frequency and dual baseline airborne sar interferometry in this paper a dual frequency and dual baseline dfdb processing framework for the extraction of high precision terrain information from airborne interferometric synthetic aperture radar sar data is presented specifically we propose the use of two single pass data sets acquired simultaneously in two different frequency bands and two large baseline repeat pass data sets also acquired simultaneously in two frequency bands the configuration profits from the stability of the single pass derived elevation maps in relation to spatially correlated artifacts as well as from the increased sensitivity associated with large baseline acquisitions moreover the dual frequency nature of the data set enables the tackling of the phase unwrapping issue promoting the retrieval of unambiguous measurements several algorithms for the interferometric processing of the dfdb airborne data set are proposed including the outline of multichannel phase calibration and unwrapping error correction strategies and approaches to remove spatially correlated artifacts and extract the common underlying topography elevation models generated from a dfdb data set acquired with the airborne f sar sensor over tidal flats in northern germany are presented and comparisons with an airborne laser scanner reference show errors with a standard deviation of around 14 cm and a mean absolute deviation of less than 10 cm