gravity driven deformation of tenerife measured by insar time series analysis 1 we study the state of deformation of tenerife canary islands using differential synthetic aperture radar interferometry dinsar we apply the small baseline subset sbas dinsar algorithm to radar images acquired from 1992 to 2005 by the ers sensors to determine the deformation rate distribution and the time series for the coherent pixels identified in the island our analysis reveals that the summit area of the volcanic edifice is characterized by a rather continuous subsidence extending well beyond las canadas caldera rim and corresponding to the dense core of the island these results coupled with gps ones structural and geological information and deformation modeling suggest an interpretation based on the gravitational sinking of the dense core of the island into a weak lithosphere and that the volcanic edifice is in a state of compression we also detect more localized deformation patterns correlated with water table changes and variations in the deformation time series associated with the seismic crisis in 2004

multiple fault slow rupture of the 2016 mw 7 8 kaikōura new zealand earthquake complementary insights from teleseismic and geodetic data

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 small baseline approach for investigating deformations on full resolution differential sar interferograms this paper presents a differential synthetic aperture radar sar interferometry difsar approach for investigating deformation phenomena on full resolution difsar interferograms in particular our algorithm extends the capability of the small baseline subset sbas technique that relies on small baseline difsar interferograms only and is mainly focused on investigating large scale deformations with spatial resolutions of about 100 spl times 100 m the proposed technique is implemented by using two different sets of data generated at low multilook data and full single look data spatial resolution respectively the former is used to identify and estimate via the conventional sbas technique large spatial scale deformation patterns topographic errors in the available digital elevation model and possible atmospheric phase artifacts the latter allows us to detect on the full resolution residual phase components structures highly coherent over time buildings rocks lava structures etc as well as their height and displacements in particular the estimation of the temporal evolution of these local deformations is easily implemented by applying the singular value decomposition technique the proposed algorithm has been tested with data acquired by the european remote sensing satellites relative to the campania area italy and validated by using geodetic measurements

gully development in the moldavian plateau of romania abstract gully erosion has been recognized as an important environmental threat in the moldavian plateau of eastern romania the main objective of this study was to define the process based gully development by providing quantitative information from long term field measurements in small catchments three main areas of monitoring gullies were explored aerial photographs of flights in 1960 and 1970 classical leveling and repeated survey through a particular close stakes grid after 1980 the caesium 137 technique has been used effectively in the areas of deposition of gully sediments to obtain reliable information on dating specific levels of sediments and to provide chronological measures of gully development most of the discontinuous gullies exhibit both proper gullying mainly if not exclusively by gully head advance and aggradation of the gully basin floor results indicated that the mean gully head retreat was 0 92 m year 1 and the mean areal gully growth was 17 0 m2 year 1 both values indicate a slow erosion rate for this area the average annual regime of gullying is pulsatory one that is best described by great fluctuations conventional measurements on sedimentation over the period 1987 1997 indicate a higher rate of aggradation in the upper half of the gully floor information on the caesium 137 depth profile was used to provide estimates of a mean sedimentation rate of 4 4 cm year 1 over the period 1963 1996 and 2 5 cm year 1 after 1986 for the short successive discontinuous gullies a new classification of the discontinuous gullies based on two criteria respectively the field patterns and the rate of aggradation within the gully basin floor was established for continuous gullies linear gully head retreat areal gully growth and eroded material rates were quantified for three periods 1961 1970 1971 1980 and 1981 1990 results indicate that gully erosion has decreased since 1960 this gullying decline is due to the rainfall distribution and the increased influence of soil conservation practices the mean gully head retreat of 12 5 m year 1 between 1961 1990 was accompanied by a mean areal gully growth of 366 8 m2 year 1 and a mean erosion rate of 4168 t year 1 as with discontinuous gullies continuous gullies showed pulsatory development the critical period for gullying over 1981 1996 covers 4 months from mid march to mid july in an area with mean annual precipitation around 500 mm another main finding of this 16 year stationary monitoring was that 57 of the total gullying occurred during the cold season with the remainder during the warm season of the total gully growth 66 results from only four years 1981 1988 1991 and 1996 when a greater amount of precipitation fell

validation of the rupture properties of the 2001 kunlun china ms 8 1 earthquake from seismological and geological observations summary we determine the finite fault slip distribution of the 2001 kunlun earthquake ms 8 1 by inverting teleseismic waveforms as constrained by geological and remote sensing field observations the spatial slip distribution along the 400 km long fault was divided into five segments in accordance with geological observations forward modelling of regional surface waves was performed to estimate the variation of the speed of rupture propagation during faulting for our modelling the regional 1 d velocity structure was carefully constructed for each of six regional seismic stations using three events with magnitudes of 5 1 5 4 distributed along the ruptured portion of the kunlun fault our result shows that the average rupture velocity is about 3 6 km s 1 consistent with teleseismic long period wave modelling the initial rupture was almost purely strike slip with a rupture velocity of 1 9 km s 1 increasing to 3 5 km s 1 in the second fault segment and reaching a rupture velocity of about 6 km s 1 in the third segment and the fourth segment where the maximum surface offset with a broad fault zone was observed the rupture velocity decelerated to a value of 3 3 km s 1 in the fifth and final segment coseismic slip on the fault was concentrated between the surface and a depth of about 10 km we infer that significant variations in rupture velocity and the observed fault segmentation are indicative of variations in strength along the interface of the kunlun fault as well as variations in fault geometry

evidence of nonlinear elasticity of the crust from the mw7 6 manyi tibet earthquake satellite synthetic aperture radar sar interferometry shows that the magnitude 7 6 manyi earthquake of 8 november 1997 produced a 170 kilometer long surface break with up to 7 meters of left lateral slip reactivating a n76 e quaternary fault in western tibet the radar interferometric map reveals asymmetric along strike displacement profiles between the two sides of the surface rupture a pattern that cannot be explained with linear elastic theory this observation suggests that the elastic moduli of the crust in tension and in compression are different because of the presence of cracks in the crust at shallow depth a model indicates that a ratio of 2 between compressive and tensile elastic moduli can account for the observed asymmetry a ratio that is consistent with laboratory and borehole measurements

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

early detection and in depth analysis of deformation phenomena by radar interferometry the spaceborne differential interferometric sar dinsar technique may play an important role in the measurement of land deformation phenomena especially in urban suburban and industrial areas in order to fully exploit its capabilities and increase its operational use this paper proposes two complementary levels of analysis the first one is a comprehensive low cost screening in order to detect unknown subsidence phenomena over large areas this analysis which provides a first estimation of deformations has to be performed using a limited set of sar images the second level includes an in depth quantitative analysis based on large image stacks which requires more image acquisition and data processing resources this type of analysis can be typically used to study deformation phenomena of special relevance where an effective support to the decision makers requires a fully quantitative estimation of deformations the two levels of analysis were proved over a test area of about 2100 km2 located in catalonia spain without any a priori information seven deformation phenomena were detected using a reduced set of interferograms furthermore the quantitative analysis of a subsidence of small spatial extent which was based on ascending and descending datasets confirmed the capability of dinsar to quantitatively assess deformation phenomena

from previous c band to new x band sar systems assessment of the dinsar mapping improvement for deformation time series retrieval in urban areas we investigate the capability improvement of the advanced differential interferometric synthetic aperture radar dinsar techniques to map deformation phenomena affecting urban areas by exploiting multitemporal sar data acquired by the new x band sensors with respect to those of the previous c band systems in particular we perform a comparative analysis of the deformation time series retrieved by applying the full resolution small baseline subset dinsar technique to selected sequences of sar data acquired by the envisat and radarsat 1 sensors both operating at c band and by the x band radar systems onboard the sar sensors of the cosmo skymed csk constellation this study focused on the city of napoli italy allows us to quantify the dramatic increase of the dinsar coherent pixel density achieved by exploiting the high resolution x band csk sar images a few meters resulting in an improvement factor of about 320 and 550 with respect to the radarsat 1 and envisat products respectively this improvement permits us to analyze nearly all the structures located within the investigated urbanized area and in many cases also portions of the same building the improved coherent pixel spatial densities combined with the reduced revisit times of the new x band sar missions allow us to significantly increase the effectiveness of the advanced dinsar methodologies further extending the role of those earth observation data in the development of monitoring scenarios

a procedure for modelling shallow dislocation sources summary expressions for displacements on the surface of a layered half space due to an arbitrary oriented shear dislocation are given in terms of generalized ray expansions useful approximations of these expressions for shallow events as recorded at teleseismic distances for realistic earth models are presented the results of this procedure are used to generate synthetic p sv and sh waveforms for various assumptions of stress drop

the 14 november 2001 kokoxili tibet earthquake high frequency seismic radiation originating from the transitions between sub rayleigh and supershear rupture velocity regimes seismic array based analysis of the major kokoxili earthquake tibet 14 november 2001 yields an unambiguous reconstruction of the seismic rupture history and relates it to the generated seismic radiation we demonstrate that after a classical sub rayleigh velocity stage the rupture speed has jumped to supershear values close to compressional wave velocity over a 175 km long fault segment before abruptly slowing down in the late part of the earthquake the transition locations between these three phases are correlated with the fault geometry and are associated with the most energetic radiation this observation proves that the rupture velocity changes as theoretically predicted are a primary source of high frequency seismic radiation this result requires reconsidering the origins of seismic damage generally attributed to slip variations

deflation of mount etna monitored by spaceborne radar interferometry ground based measurements of volcano deformation can be used to assess eruptive hazard but require the costly and often hazardous installation and maintenance of an instrument network here we show that spaceborne radar interferometry which has already shown its utility in mapping earthquake related deformation1 can be used to monitor long term volcano deformation two families of synthetic aperture radar images acquired from ascending and descending orbits by the satellite ers 1 and looking at mount etna from opposite sides cover the time period from 17 may 1992 to 24 october 1993 and include the second half of etna s most recent eruption despite artefacts of the interferometric technique we can observe a volcano wide deflation which is an expected consequence of the eruption but which had not previously been appreciated we quantify it using a simple model based on the change of pressure in a sphere located in an elastic half space the modelled deformation increases linearly with time until the end of the eruption our results show that it will be possible to use this technique to detect the inflation of volcanic edifices that usually precedes eruptions

fault geometry and distribution of asperities of the 1997 manyi china mw 7 5 earthquake integrated analysis from seismological and insar data 1 the integration of seismic and insar interferogram data allows us to have a comprehensive understanding of the earthquake fault geometry and distribution of asperities for a remote event namely the 1997 manyi china earthquake we first obtained the slip distribution from teleseismic stations for several fault models and then made synthetic interferograms in order to determine the optimum fault geometry our results show that the 1997 manyi earthquake ruptured bilaterally with two segments dipping north and south for the western and eastern segments respectively the south dip of the eastern segment is essential for a better interpretation of the stations near the nodal plane and a reversal of dip between the west and east segment is necessary to explain the pattern of observed insar interferograms due to the broader distribution of asperities the fault rupture extended 170 km with maximum displacement of 6 1 m and a total seismic moment of 2 24 10 20 nm mw 7 5

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

multiple causes of ground deformation in the napoli metropolitan area italy from integrated persistent scatterers dinsar geological hydrological and urban infrastructure data abstract this study presents a differential sar interferometry dinsar analysis and review of ers 1992 2001 and radarsat 2003 2007 data on the city of napoli italy these data are processed using the persistent scatterers interferometric synthetic aperture radar psinsar technique and post processed by statistical selection and filtering with the aim to obtain by combining ascending and descending geometries the spatial distribution of the vertical and horizontal east west components of the ground displacement velocity we identify five main areas of subsidence affecting residential districts and strategic infrastructures transportations and industrial plants these are a vomero arenella district b scudillo stella district c municipio square d garibaldi square and e poggioreale district in these areas the ground deformation rate is between 1 3 and 10 5 mm yr and varies through time in particular in the investigated time period the subsidence rate i persistently increases in the scudillo stella and poggioreale districts ii abruptly increases in correspondence of underground construction activities municipio and garibaldi squares and iii decreases following the ground deformation style of the campi flegrei caldera vomero arenella district more restricted areas of subsidence also occur in the northeastern less urbanized sectors of the napoli metropolitan area the subsidence triggering factors are investigated through a review of the available geological geomorphological hydrological and urban network information with respect to other urban contexts where the cause of subsidence is of natural or anthropogenic origin napoli shows a multiple association of triggering factors these factors are sub soil excavations for the construction of transport infrastructures filling emptying cycles of large underground water reservoirs gravity instability related to local morphological factors raise of the water table with consequent hydrocompaction due to the stop of ground water withdrawal and re activation of volcano tectonic faults associated to the uplift and subsidence phases bradyseism of the neighboring active campi flegrei caldera whose western sector includes a part of the napoli urban area we conclude that in a complex urban and geological setting like that of napoli ground deformations induced by anthropic and natural processes may coexist and should be monitored for a correct evaluation of the associated hazard and the management of the city planning activities finally the combined review of satellite and geological data available for different urban districts worldwide is essential to identify the sources of ground deformation and analyze the time evolution of the related anthropic and or natural processes

enhanced landslide investigations through advanced dinsar techniques the ivancich case study assisi italy abstract we extensively exploit advanced differential sar interferometry dinsar techniques for enhanced landslide investigations we focus on the ivancich area assisi central italy which is affected by a deep seated landslide investigated through in situ surveys for this area large data sets of sar acquisitions were collected by the c band ers 1 2 and envisat sensors from april 1992 to november 2010 and by the x band radars of the cosmo skymed csk constellation from december 2009 to february 2012 we concentrate on the advanced dinsar technique referred to as small baseline subset sbas approach benefiting of its capability to generate deformation time series at full spatial resolution and from multi sensor sar data this allows us to present one of the first examples for a landslide area of ers 1 2 envisat deformation time series exceeding 18 years the results allowed characterizing the long term behaviour of the landslide and identifying sectors of the unstable slope affected by different deformation dynamics analysis of the csk data set characterized by a reduced revisit time and improved spatial resolution resulted in a 15 time larger point density with respect to the ers envisat measurements allowing to investigate nearly all the buildings and in many cases portions of buildings in the landslide area lastly we present an innovative modelling approach based on the effective integration of the dinsar measurements with traditional geological and geotechnical information providing deeper insights on the kinematical evolution of the landslide we consider our analysis a prototype example that can be extended to different geological and geotechnical conditions providing significant advances in the understanding of ground deformations induced by active landslides

effects of land use changes in vegetation cover and sidewall erosion in a gully head of the penedes region northeast spain the present research addresses the effects of land use changes in the evolution of vegetation cover on gully erosion in the penedes region of northeast spain the contribution of vegetation cover to gully wall stabilization is also discussed the catchment area of the gully is 60 2 ha and is mainly composed of vineyards in this area large gullies have developed on tertiary marls and unconsolidated sandstones detailed aerial photographs 1 5000 and 1 7000 scale of three dates 1975 1995 and 2002 were ortho rectified to derive land use information in the catchment gully vegetation cover and height information to construct detailed digital elevation models land use and gully vegetation cover mapping of the most recent period was assisted by means of fieldwork and a photo interpretation key constructed to help map the older dates soil loss in the catchment was estimated for the 1975 and 2002 scenarios to determine the relations between land use changes to vegetation cover changes and gully sidewall erosion the revised universal soil loss equation was applied for that purpose sidewall mass movements were determined by subtraction of digital elevation models 1 m resolution of each period the results show important land use changes in the catchment due to field reorganization for the plantation of mechanized vineyards it increased soil loss from agricultural fields by 26 5 which influenced vegetation cover dynamics on gully walls with an important development of scrubland to forest and gully erosion with sidewall retreat at rates of 0 025 to 0 50 ha y 1 and mass movements at rates of 16 to 63 2 mg ha 1 y 1 these results indicate that vegetation cover on gully walls although suggesting an improvement with respect to wall protection against splash sheet and rill erosion did not affect sidewall retreat and mass movements copyright 2009 john wiley sons ltd

geochronological position of badlands and geomorphological patterns in the guadix baza basin se spain abstract the guadix baza basin is one of a number of intramontane depressions located within the betic cordillera se spain where the geological and geomorphological evolution is controlled by tectonic activity the basin ceased to be closed after capture by the atlantic network when five main land systems developed late pleistocene geological evolution basically consisted of erosional modelling when badlands were deeply incised in highly erodible materials marls and silts three travertine platforms and several palaeolithic sites were used to determine that this main incision period fell within a 115 000 48 000 yr range there are few signs of geomorphological evolution of this basin in the last 48 000 yr based on these geomorphological data and soil development tectonic uplift of the basin probably played a secondary role in its evolution and climatic conditions in southern iberia in the 144 000 48 000 yr period were more humid and variable than later

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

synthetic aperture radar interferometry to measure earth s surface topography and its deformation synthetic aperture radar interferometry insar from earth orbiting spacecraft provides a new tool to map global topography and deformation of the earth s surface radar images taken from slightly different viewing directions allow the construction of digital elevation models of meter scale accuracy these data sets aid in the analysis and interpretation of tectonic and volcanic landscapes if the earth s surface deformed between two radar image acquisitions a map of the surface dis placement with tens of meters resolution and subcentimeter accuracy can be con structed this review gives a basic overview of insar for earth scientists and presents a selection of geologic applications that demonstrate the unique capabilities of insar for mapping the topography and deformation of the earth

deformation and eruptions at mt etna italy a lesson from 15 years of observations this work was partly funded by ingv and the italian dpc and was supported by asi the preview project and crdc amra dpc ingv flank project providing the funds for the publication fees

fault slip in the 1997 manyi tibet earthquake from linear elastic modelling of insar displacements summary the mw 7 6 1997 manyi earthquake occurred in an area of central northern tibet where sparse vegetation coverage and a lack of human habitation provide excellent conditions for interferometric synthetic aperture radar insar studies we use coseismic pairs of radar images acquired by the esa ers 2 satellite to construct interferograms of the surface displacement field due to the earthquake the location and extent of the coseismic fault rupture are mapped using a combination of optical satellite imagery high resolution digital topography interferometric correlation and azimuth offset measurements in so doing we are able to relate prominent geomorphic features in the fault zone to bends in the fault using elastic dislocation models consistent with this mapped fault trace we then test a range of fault geometries and slip conditions to find the combination which best explains the insar displacements our favoured model contains a reversal in fault dip approximately halfway along its length occurring at the location of a restraining bend slip on this model fault is heterogeneous with two areas of peak slip of 7 m or greater and components of dip slip displacement which vary significantly along strike the success of this model in fitting the data implies that an observed asymmetry in the coseismic interferograms can be explained in terms of the local fault geometry rather than by using non linear elastic rheologies as suggested by earlier authors

structural analysis of the 1997 mw 7 5 manyi earthquake and the kinematics of the manyi fault central tibetan plateau abstract on 8th november 1997 the mw 7 5 manyi earthquake ruptured the left lateral strike slip manyi fault in the central tibetan plateau despite its large magnitude a comprehensive geological study on the co seismic surface rupture has not yet been reported so far here we reported on our new results of the co seismic surface ruptures and left lateral offsets caused by the earthquake based on detailed interpretation of recently acquired high resolution worldview and spot 5 images we recognized a primary 185 km long surface rupture that trends n80 e in consistence with previous results along the poorly developed segment at the eastern end of the manyi fault a new rupture is also identified which trends n57 e and extends 17 km the co seismic surface rupture zone exhibits many distinct features such as stepovers extensional cracks ponds restraining and releasing bends in relation to fault geometrical complexities by visual analysis of the displaced geomorphic features using satellite imagery we measured 198 co seismic offsets along the 200 km fault trace the results show a 3 7 m average offset and a maximum offset of up to 7 5 m near the epicenter area the newly found 17 km long rupture is interpreted to be linked to the main fault during the event if the manyi fault continues this northeastward propagation for additional 100 km it will separate the bayanhar block into two sub blocks such a new hypothetical block model will influence assessment of seismic potential near the block boundaries and estimate of deformation of the bayanhar block and the central tibetan plateau

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

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

atmospheric limitations to repeat track radar interferometry in its recent radar imaging mission the shuttle imaging radar satellite sir c devoted three days to repeat track interferometry we have analyzed the data from a test site in the mojave desert of california although good topography 10 m on 21 m postings was obtained most of the error was caused by turbulent water vapor in the lower atmosphere spatial structure of 6 km and all smaller sizes was observed the rms one way time delay was found to be 0 24 cm essentially identical results were obtained at two wavelengths 24 and 5 7 cm

gully distribution and development in moldavia romania abstract in a study area in romania covering about 25 000 km 2 over 9000 gullies were mapped and 12 were surveyed in detail the distribution of gullies indicates that the highest gully density reflects hillslope orientation inclination and length and a sandy lithology the surface deposits of gullies studied vary from silty clays in the northern half of the territory to silts in the middle to southern area and sands in the southern end of the region factorial analysis of geometrical and granulometrical variables showed the role of the m parameter as a discriminating value of gully cross section shape the rate of gully head cutting is over 1 5 m year for gullies cut in sandy deposits and under 1 m year for the gullies cut in marls and clays a model of gully development is proposed which shows an accelerated rate of gully development immediately downstream after their initiation and a reduced and even cessation of advance on attaining an equilibrium length

surface deformation of long valley caldera and mono basin california investigated with the sbas insar approach abstract we investigate the surface deformation of the eastern california area that includes long valley caldera and mono basin we apply the sar interferometry insar algorithm referred to as small baseline subset sbas approach that allows us to generate mean deformation velocity maps and displacement time series for the investigated area the results presented in this work represent an advancement of previous insar studies of the area that are mostly focused on the deformation affecting the caldera in particular the proposed analysis is based on 21 sar data acquired by the ers 1 2 sensors during the 1992 2000 time interval and demonstrates the capability of the sbas procedure to identify and analyze displacement patterns at different spatial scales for the overall area spanning approximately 5000 km2 two previously unreported localized deformation effects have been detected at paoha island located within the mono lake and in the mcgee creek area within the sierra nevada mountains a zone to the south of the long valley caldera in addition a spatially extended uplift effect which strongly affects the caldera has been identified and analyzed in detail the insar results clearly show that the displacement phenomena affecting the long valley caldera have a maximum in correspondence of the resurgent dome and are characterized by the sequence of three different effects a 1992 1997 uplift background a 1997 1998 unrest phenomenon and a 1998 2000 subsidence phase moreover the analysis of the retrieved displacement time series allows us to map the extent of the zone with a temporal deformation behavior highly correlated with the detected three phases deformation pattern background uplift unrest subsidence we show that the mapped area clearly extends outside the northern part of the caldera slopes accordingly we suggest that future inversion models take this new evidence into account the final discussion is dedicated to a comparison between the retrieved insar measurements and a set of gps and leveling data confirming the validity of the results achieved through the sbas insar analysis

satellite radar interferometry time series analysis of surface deformation for los angeles california 1 the los angeles california metropolitan area is a tectonically active region with surface deformation that is a combination of fault related tectonics plus a variety of natural and anthropogenic signals we apply the small baseline subset sbas algorithm to produce an interferometric synthetic aperture radar insar time series analysis for the los angeles area using data acquired by the ers satellites from late 1995 into 2002 the result is a space time deformation product that can be exploited to view not only the smoothly varying long term surface motion but also its time varying patterns large seasonal oscillations of the santa ana aquifer observed in southern california integrated gps network scign data are accurately matched in the insar time series moreover correlations of the insar time series with an annual sinusoid allows us to investigate the dynamics of the hydrologic system index terms 1243 geodesy and gravity space geodetic surveys 1294 geodesy and gravity instruments and techniques 1803 hydrology anthropogenic effects citation lanari r p lundgren m manzo and f casu 2004 satellite radar interferometry time series analysis of surface deformation for los angeles california geophys res lett 31 l23613 doi 10 1029 2004gl021294

surface displacement of the 17 may 1993 eureka valley california earthquake observed by sar interferometry satellite synthetic aperture radar sar interferometry shows that the magnitude 6 1 eureka valley earthquake of 17 may 1993 produced an elongated subsidence basin oriented north northwest parallel to the trend defined by the aftershock distribution whereas the source mechanism of the earthquake implies a north northeast striking normal fault the 3 millimeter accuracy of the radar observed displacement map over short spatial scales allowed identification of the main surface rupture associated with the event these observations suggest that the rupture began at depth and propagated diagonally upward and southward on a west dipping north northeast fault plane reactivating the largest escarpment in the saline range

broadband source modeling of the november 8 1997 tibet mw 7 5 earthquake and its tectonic implications we studied the source process of a large ms 7 9 intraplate earthquake that occurred on november 8 1997 at 1002 ut in a remote region of northern tibet we used four distinct methods to investigate the broadband source process and thereby better understand the tectonic implications of this event we relocated aftershocks using a master event technique and found that the distribution of aftershocks covers a region of 200 km in lateral extent we also employed a surface wave spectral inversion technique to estimate the mainshock moment depth centroid location and centroid time and utilized an empirical green s function technique to extract rupture directivity information and a detailed source time function from observed seismograms we also inverted body waves to estimate the moment release along the fault and the source time function the 1997 earthquake ruptured a strike slip fault that appears to be an extension or splay of the kun lun fault system this fault is one of the most seismically active strike slip faults within the tibetan plateau and has had events with surface wave magnitudes of 6 1 7 4 and 7 9 in this region since 1973 the rupture released most of the energy within the first 20 s and propagated bilaterally initially with the later rupture propagating westward for 20 30 s the absence of large aftershocks suggests that the earthquake efficiently released the stored strain comparing mainshock to the largest aftershock energy ratios for this event and other large strike slip events shows that faulting within the plateau has the characteristics of weak faults e g fracture zone faulting

application of sar interferometry to a large thrust deformation the 1999 mw 7 6 chichi earthquake in central taiwan summary application of the interferometric method to four ers2 sar images acquired before and after the 1999 chichi earthquake has allowed determination of the coseismic surface displacement in the footwall area of the chelungpu fault the interferometric results revealed a relative shortening in the round trip distance between the radar antenna and the ground of the footwall side of chelungpu fault during the earthquake this shortening progressively increased from the west to the east and reaches the maximum amount of approximately 26 cm near the central segment of the chelungpu fault our interferometric results have been precisely examined using a dense gps network in the investigated area we mapped the gps coseismic measurements into the radar line of sight and implemented a forward simulation of sar interferogram from this synthesized result to control our unwrapping performance in this study these two observations are compared with a 3 d dislocation model of the fault finally a deformation analysis based on our interferometric result has indicated that a segment with irregular deformation behaviour can be distinguished in the footwall area of the chelungpu fault this segment may result from either the influence of inherited basement faults or the presence of a structural terrace that provide local opportunities for superficial deformation

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

on the joint exploitation of long term dinsar time series and geological information for the investigation of ground settlements in the town of roma italy abstract in this work the long term dinsar deformation time series have been jointly exploited with the geological information and the structural characteristics of the buildings in order to study the interactions between the soils and the man made structures and to investigate the response of different buildings to the settlements the presented analysis has been carried out by applying the advanced multi temporal dinsar technique referred to as small baseline subset sbas approach to an ers envisat sar dataset collected over the town of roma italy in the 1992 2010 time interval our study has been performed first at the large spatial scale and then at the local scale focusing on some buildings located within the city centre on the eastern side of the tevere river the obtained sbas dinsar measurements analysed in light of the geological setting and the spatial distribution of the settlements indicate that the observed displacements are mainly linked to a residual consolidation process correlated with the urbanization and hydrometric level of the tevere river the local variation in the deformation rates can be related to the intrinsic variability of the soils filling the alluvial valley and to time since loading application

persistent scatterer selection using maximum likelihood estimation 1 we present here a new insar persistent scatterer selection method using maximum likelihood estimation to identify persistent scattering pixels which results in a denser network of reliable phase measurements than do existing methods we analyze the phase of each pixel in a series of interferograms and estimate the relative strength of any slowly fluctuating component of the radar echo from a dominant scatterer to the background scattering within a pixel we find a fairly dense network of scatterers with stable phase characteristics in areas where conventional insar fails due to decorrelation we examined data over two vegetated regions in the san francisco bay area the average phases of these pixels clearly show the slip along the hayward fault and set upper bounds on any slip along the bay area segment of the san andreas fault

remotely sensing large and small scale ground subsidence a case study of the guangdong hong kong macao greater bay area of china abstract as the world s largest city cluster the guangdong hong kong macao greater bay area gba is vulnerable to significant subsidence the widely distributed sediments and rapid urbanization in the gba result in the concurrence of large and small scale subsidence mono sensor synthetic aperture radar sar images usually suffer from the limitation of either low resolution or small coverage and thus are not applicable to completely monitoring the gba in this study we used sentinel 1 s1 cosmo skymed csk and terrasar x tsx images jointly to reveal multi scale subsidence of the gba the overall subsidence ranged from 0 to 112 3 mm yr derived from the 2015 2017 s1 images three regional subsidence bowls zhuhai zhongshan jiangmen and guangzhou zhongshan formed in the western alluvial plain the high correlation between regional subsidence and quaternary sediments confirms that sediment consolidation is the main cause of subsidence the land use and numerical modeling results suggest that groundwater extraction and artificial loading are the triggering factors two representative local subsidence cases were analyzed using high resolution images reclamation settlement at the hong kong international airport hkia and sinkhole subsidence due to the excavation of the shenzhen wenbo skyscraper foundation pit the validation at the hkia showed that the measurements from the csk and s1 data both agreed well with the leveling data however csk outperformed s1 in the sense that it increased the point density by a factor of 5 improved the height precision by a factor of 4 and showed fewer false alarms csk is therefore more applicable to monitoring the local subsidence of key infrastructures the cross heading tracks of tsx and csk images detected precursory subsidence before the sinkhole collapse from two sides indicating that the cross heading tracks benefit the comprehensive monitoring of local subsidence in high rise and high density built environments in summary the synergistic use of multi sensor sar images demonstrates the practicability of the operational surveillance of multi scale subsidence from regional surveying to the fine monitoring of local areas in the gba

improving regional seismic event location in china in an effort to improve our ability to locate seismic events in china using only regional data we have developed empirical propagation path corrections and applied such corrections using traditional location routines thus far we have concentrated on corrections to observed p arrival times for crustal events using travel time observations available from the usgs earthquake data reports the international seismic centre bulletin the preliminary international data center reviewed event bulletin and our own travel time picks from regional data location ground truth for events used in this study ranges from 25 km for well located teleseimic events down to 2 km for nuclear explosions located using satellite imagery we also use eight events for which depth is constrained using several waveform methods we relocate events using the evloc algorithm from a region encompassing much of china latitude 20 55 n longitude 65 115 e we observe that travel time residuals exhibit a distance dependent bias using iaspei91 as our base model to remedy this bias we have developed a new 1 d model for china which removes a significant portion of the distance bias for individual stations having sufficient p wave residual data we produce a map of the regional travel time residuals from all well located teleseismic events residuals are used only if they are smaller than 10 s in absolute value and if the seismic event is located with accuracy better than 25 km from the residual data correction surfaces are constructed using modified bayesian kriging modified bayesian kriging offers us the advantage of providing well behaved interpolants and their errors but requires that we have adequate error estimates associated with the travel time residuals from which they are constructed for our p wave residual error estimate we use the sum of measurement and modeling errors where measurement error is based on signal to noise ratios when available and on the published catalog estimate otherwise our modeling error originates from the variance of travel time residuals for our 1 d china model we calculate propagation path correction surfaces for 74 stations in and around china including six stations from the international monitoring system the statistical significance of each correction surface is evaluated using a cross validation technique we show relocation results for nuclear tests from the balapan and lop nor test sites and for earthquakes located using interferometric synthetic aperture radar these examples show that the use of propagation path correction surfaces in regional relocations eliminates distance bias in the residual curves and significantly improves the accuracy and precision of seismic event locations

nonuniform ground motion monitoring with terrasar x persistent scatterer interferometry in the past the application of persistent scatterer interferometry psi was primarily possible in the case of slow less than a few centimeters per year uniform movements in this paper we show how psi permits the monitoring of relatively fast including rates up to 50 cm year and nonuniform movements using terrasar x repeat observations over deep level mining to enable this parts of the psi methodology were adapted to the special characteristics of the example studied apart from a description of the methodology used and the result achieved error considerations and a validation of the result with in situ measurements are included

modes of raising northeastern tibet probed by explosion seismology abstract new wide angle reflection and refraction seismic data provide constraints on the structure of the upper lithosphere and test models of its evolution to raise the northeastern part of the tibetan plateau amplitudes observed for reflections from the crust mantle boundary are sufficiently large to suggest that there is no significant partial melt in the deep crust the data show an increase of the crustal thickness between terranes from north of the kun lun fault into the qang tang of central tibet and a contrast among their intracrustal images and compositions in the north p and s velocities are consistent with a dominantly felsic composition and show that only the upper crust thickened south of the kun lun fault a thicker crust made of two layers could result from the superposition of the originally thin crust of the bayan har terrane on the lower part of the crust of the domain to the north which upper crust it shoved and thickened different modes of crustal thickening either by thickening of individual layers or superpositions and imbrication among them appear to work jointly to raise the topography

a method for the joint inversion of geodetic and seismic waveform data using abic application to the 1997 manyi tibet earthquake geodetic imaging data and seismicwaveformdata have complementary strengthswhen considering the modelling of earthquakes the former particularly modern space geodetic techniques such as interferometric synthetic aperture radar insar permit high spatial density of observation and thus fine resolution of the spatial pattern of fault slip the latter provide precise and accurate timing information and thus the ability to resolve how that fault slip varies over time in order to harness these complementary strengths we propose a method through which the two data types can be combined in a joint inverse model for the evolution of slip on a specified fault geometry we present here a derivation of akaike s bayesian information criterion abic for the joint inversion of multiple data sets that explicitly deals with the problem of objectively estimating the relative weighting between data sets as well as the optimal influence of model smoothness constraints in space and time we demonstrate our abic inversion scheme by inverting insar displacements and teleseismic waveform data for the 1997 manyi tibet earthquake we test using a simplified fault geometry three cases insar data inverted alone vertical component teleseismic broad band waveform data inverted alone and a joint inversion of both data sets the insar only model and seismic only model differ significantly in the distribution of slip on the fault plane that they predict the joint inversion model however has not only a similar distribution of slip and fit to the insar data in the insar only model suggesting that those data provide the stronger control on the pattern of slip but is also able to fit the seismic data at a minimal degradation of fit when compared with the seismic only model the rupture history of the preferred joint inversion model indicates bilateral rupture for the first 20 s of the earthquake followed by a further 25 s of westward unilateral rupture afterwards with slip peaking at 7m in the upper 6 km of the fault this joint inversion approach is thus shown to be a viable method for the study of large shallow continental earthquakes and may be of particular benefit in cases where near field seismic observations are not available the authors 2014 published by oxford university press on behalf of the royal astronomical society