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

a field based model of permafrost controlled rockslide deformation in northern norway abstract knowledge about the detailed processes linked to the existence of permafrost in rockslide fractures is sparse large parts of the jettan rockslide are located right below the discontinuous permafrost limit in the arctic part of the alpine landscape of northern norway combining four years of meteorological and rockslide deformation data with temperature measurements from different parts of open fractures shallow bedrock boreholes and air as well as daily snow cover observations allows a detailed identification of the key processes involved these field data are the basis for the development of a permafrost controlled rockslide model seasonally the deformation has a very distinctive pattern with high deformation starting abruptly right after snowmelt in may and lasting until snow isolation in winter then there is a gradual transition to medium deformation as the ground is cooled further for another 1 2 months finally the winter period when maximum snow occurs in the fractures is characterized by limited or almost no deformation the primary controlling deformation process is meltwater percolation into fractures in summer with significant refreezing ice formation and temperature increase in the lower part of the fractures from 1 c to 0 c sporadic permafrost exists below the discontinuous permafrost limit and may extend into open fractures and sliding planes another primary process is the significant cold air accumulation in fractures in early winter due to the balch effect which significantly cools the fracture and surrounding rock promoting permafrost development finally the cold air effect is stopped by snow isolation once enough snow has accumulated in the fracture by late winter the deformation itself is thought to be controlled by changing shear strength of the brecciated sliding planes due to either changing ice temperatures and or variations in water infiltration to the unsaturated sliding zones the overall system is very locally controlled driving itself and the effect of a future climate change can thus be of minor importance

toward mapping surface deformation in three dimensions using insar 1 one of the limitations of deformation measurements made with interferometric synthetic aperture radar insar is that an interferogram only measures one component of the surface deformation in the satellite s line of sight we investigate strategies for mapping surface deformation in three dimensions by using multiple interferograms with different imaging geometries geometries for both current and future missions are evaluated and their abilities to resolve the displacement vector are compared the north component is always the most difficult to determine using data from near polar orbiting satellites however a satellite with an inclination of about 60 120 would enable all three components to be well resolved we attempt to resolve the 3d displacements for the 23 october 2002 nenana mountain alaska earthquake the north component s error is much larger than the signal but proxies for eastward and vertical motion can be determined if the north component is assumed negligible inversions of hypothetical coseismic interferograms demonstrate that earthquake model parameters can be well recovered from two interferograms acquired on ascending and descending tracks

insar measurements of surface deformation over permafrost on the north slope of alaska 1 ground based measurements of active layer thickness provide useful data for validating calibrating remote sensing and modeling results however these in situ measurements are usually site specific with limited spatial coverage here we apply interferometric synthetic aperture radar insar to measure surface deformation over permafrost on the north slope of alaska during the 1992 2000 thawing seasons we find significantly systematic differences in surface deformation between floodplain areas and the tundra covered areas away from the rivers using floodplain areas as the reference for insar s relative deformation measurements we find seasonally varying vertical displacements of 1 4 cm with subsidence occurring during the thawing season and a secular subsidence of 1 4 cm decade we hypothesize that the seasonal subsidence is caused by thaw settlement of the active layer and that the secular subsidence is probably due to thawing of ice rich permafrost near the permafrost table these mechanisms could explain why in situ measurements on alaskan north slope reveal negligible trends in active layer thickness during the 1990s despite the fact that atmospheric and permafrost temperatures in this region increased during that time this study demonstrates that surface deformation measurements from insar are complementary to more traditional in situ measurements of active layer thickness and can provide new insights into the dynamics of permafrost systems and changes in permafrost conditions

hot fluid flows around a major fault identified by paleothermometric studies tim mersoi basin niger abstract faults are mostly considered as low permeability zones due to their frequent sealing but they can also contribute significantly to fluid movements in sedimentary basins and subsequently to temperature anomalies in favorable cases paleo temperatures and pressures can be determined from fluid inclusion and chlorite thermometry using this approach we estimate the temperature gap between incoming fluids and host rocks along the arlit fault a major fault affecting the whole series of continental siliciclastic formations from paleozoic to late jurassic in the tim mersoi basin niger strong alteration halos and uranium deposits occur along this regional north south trending fault as well as a secondary network of ne sw faults sandstone porosity is partially reduced by authigenic quartz and fe rich trioctahedral chlorites the chlorites precipitated directly from the solutions under reducing conditions prior to uranium oxide deposition the temperatures and pressures are estimated to be around 115 150 c and 80 120 bars respectively and are remarkably similar in all formations from the carboniferous to the jurassic these temperatures are much higher around 60 80 c than those estimated at maximum burial and document hot fluid flow along the major fault this thermal anomaly is inferred to be related to the opening of the atlantic ocean during the cretaceous before the onset of the main exhumation stages during the mid tertiary this study documents the role of faults as significant conduits for fluid flow and their role in the mass and heat transfer related to the formation of economic deposits

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

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

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

land subsidence in central mexico detected by alos insar time series abstract massive groundwater extraction is common throughout mexico and is well known to result in land subsidence however most land subsidence surveys focus on one single city mainly mexico city and thus fail to reveal the regional extent of the problem here we use 2007 2011 interferometric synthetic aperture radar insar time series analysis of alos data to resolve land subsidence in the entire central mexico region we identify land subsidence in 21 areas including 17 cities linear vertical rates over 30 cm yr are observed in mexico city while in the other locations rates of 5 10 cm yr are detected we define 3 main categories of subsidence using the averaged velocity maps in conjunction with previously published structural surface geology and land use mapping 1 rapid large scale subsidence 2 rapid local scale subsidence and 3 slow patchy subsidence the correlation between subsidence and land use confirms that groundwater extraction mainly for agricultural and urban activities is the main cause of land subsidence we observe that the boundaries of the subsiding areas are typically characterized by high velocity gradients often coinciding with pre existing faults motion on these faults being driven by water extraction rather than by tectonic activity regional surveys of this type are necessary to understand the spatial and temporal evolution of land subsidence to constrain the distribution and connectivity of water bearing units and ultimately to reach better hazard mitigation plans

transient strain accumulation and fault interaction in the eastern california shear zone satellite synthetic aperture radar interferometry reveals transient strain accumulation along the blackwater little lake fault system within the eastern california shear zone the surface strain map obtained by averaging eight years 1992 2000 of earth resource satellite ers radar data shows a 120 km long 20 kmwide zone of concentrated shear between the southern end of the 1872 owens valley earthquake surface break and the northern end of the 1992 landers earthquake surface break the observed shear zone is continuous through the garlock fault which does not show any evidence of left lateral slip during the same time period a dislocation model of the observed shear indicates right lateral slip at 7 6 3 mm yr on a vertical fault below 5 km depth a rate that is two to three times greater than the geologic rates estimated on northwest trending faults in the eastern mojave area this transient slip rate and the absence of resolvable slip on the garlock fault may be the manifestation of an oscillatory strain pattern between interacting conjugate fault systems

a gps velocity field for fennoscandia and a consistent comparison to glacial isostatic adjustment models in fennoscandia the process of glacial isostatic adjustment gia drives ongoing crustal deformation crustal velocities from gps observations have proved to be a useful tool in constraining gia models however reference frame uncertainties plate tectonics intraplate deformations as well as other geophysical processes contaminate the results former studies have shown that different international terrestrial reference frames have large discrepancies especially in the vertical component which hamper geophysical interpretation we present new velocity estimates for the fennoscandian and north european gps network our gps velocity field is directly realized in a gia reference frame using this method named the gia frame approach we are able to constrain gia models with minimal influence of errors in the reference frame or biasing signals from plate tectonics the drawbacks are more degrees of freedom that might mask real but unmodeled signals monte carlo tests suggest that our approach is robust at the 97 level in terms of correctly separating different models of ice history but depending on deformation patterns the identified earth model may be slightly biased in up to 39 of cases we compare our results to different one and three dimensional gia models employing different global ice load histories the gia models generally provide good fit to the data but there are still significant discrepancies in some areas we suggest that these differences are mainly related to inaccuracies in the ice models and or lateral inhomogeneities in the earth structure under fennoscandia thus gia models still need to be improved but the gia frame approach provides a base for further improvements

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

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

statistical analysis of seasonal displacements at the nordnes rockslide northern norway abstract the nordnes rockslide in northern norway poses a threat to local settlements along the nearby fjord due to its potential of generating tsunamis therefore a monitoring program was initiated in 2007 evaluation of the resulting monitoring data is expected to provide important contributions to the understanding of the sliding mechanisms this paper focuses on statistical analyses of continuous laser and crackmeter measurements at the nordnes rockslide during a period of 16 months annual linear displacements and seasonal fluctuations were estimated from time series of 3 lasers and 10 crackmeters results from the analyses show that the north westernmost part of the area has the largest movement of more than 5 cm per year which makes this part the most critical in terms of generation of a rapid rockslide the amplitudes of the seasonal fluctuations estimated from crackmeter time series were approximately 0 5 mm the largest displacements clearly occur in autumn and early winter with a stagnation or retreat phase in spring and summer thus the movements are not increased during snowmelt which is a normal seasonal characteristic elsewhere although the temperature changes have a significant effect on the observed displacements the seasonal variations could not fully be modelled with temperature terms in the regression models suggesting that there are other additional controlling factors the rockslide is localized in arctic and periglacial conditions and the documented seasonal variations are interpreted to be linked to effects of deformations caused by seasonal frost and permafrost prediction intervals for future displacements were also derived from the current time series these prediction intervals are considered useful for the evaluation of future measurements and may serve as basis for defining alert thresholds for possible future early warning systems

detailed rockslide mapping in northern norway with small baseline and persistent scatterer interferometric sar time series methods rockslides have a high socioeconomic and environmental importance in many countries norway is particularly susceptible to large rockslides due to its many fjords and steep mountains one of the most dangerous hazards related with rock slope failures are tsunamis that can lead to large loss of life it is therefore very important to systematically identify potential unstable rock slopes traditional landslide monitoring techniques are expensive and time consuming differential satellite interferometric synthetic aperture radar insar is an invaluable tool for land displacement monitoring improved access to time series of satellite data has led to the development of several innovative multitemporal algorithms small baseline sb methods are based on combining and inverting a set of unwrapped interferograms that are computed with a small perpendicular baseline in order to reduce spatial phase decorrelation another well proven technique is the persistent scatterer interferometric method psi that is based on analysis of persistent point targets in this paper we apply both approaches to study several rockslide sites in troms county in the far north of norway moreover we take the opportunity to address the difference and similarities between the sb and the psi multitemporal insar methods for displacement studies in rural terrain

transferability of geomorphological distribution models evaluation using solifluction features in subarctic and arctic regions extrapolation potential of statistically based geomorphological distribution models gdms has not been scrutinized here the possibility to transfer solifluction models within and between six study areas in subarctic and arctic environments was examined a generalized linear model generalized additive model maximum entropy and boosted regression tree methods were used in the analyses the transferability success of the gdms was assessed by the area under the curve of a receiver operating characteristic plot based on the results slope angle mean annual air temperature and a remote sensing based index of vegetation abundance were the most important variables contributing to the occurrence of solifluction at a landscape scale in model extrapolation over half of the calibrated solifluction models were transferable from one area to another the topographical conditions of the study areas had a greater effect than climate conditions on the extrapolation potential more precisely it was more difficult to extrapolate the models to a high relief environment than to an area with moderate topography on the contrary the models transferred within arctic and subarctic areas were not better than the models between the arctic and subarctic environments in conclusion i region specific geomorphological and environmental conditions may significantly affect the relative importance of variables in gdms ii solifluction models were transferable with certain limitations across areas iii the range of the environmental conditions of the calibration area was a critical factor for transferability success and iv machine learning based methods performed marginally better than parametric models in the model extrapolation extensive knowledge about the transferability of gdms in space is needed before the models can be reliably used in climate change explorations

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

hypoxia in the lower st lawrence estuary how physics controls spatial patterns 1 a laterally integrated advection diffusion two dimensional model was implemented to simulate the spatial distribution of dissolved oxygen and the development of hypoxic conditions in the deep waters of the laurentian channel estuary and gulf of st lawrence eastern canada our simulations reveal that the horizontal distribution of dissolved oxygen in the bottom waters of the laurentian channel is determined by a combination of physical and biogeochemical processes whereas its vertical distribution is governed by the deep water circulation this result strongly suggests that the physics of the system and the source water properties are mostly responsible for the generation of a mid water column oxygen minimum and the oxygen distribution pattern in the deep water column

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

estimating 1992 2000 average active layer thickness on the alaskan north slope from remotely sensed surface subsidence 1 the measurement of temporal changes in active layer thickness alt is crucial to monitoring permafrost degradation in the arctic we develop a retrieval algorithm to estimate long term average alt using thaw season surface subsidence derived from spaceborne interferometric synthetic aperture radar insar measurements our algorithm uses a model of vertical distribution of water content within the active layer accounting for soil texture organic matter and moisture we determine the 1992 2000 average alt for an 80 100 km study area of continuous permafrost on the north slope of alaska near prudhoe bay we obtain an alt of 30 50 cm over moist tundra areas and a larger alt of 50 80 cm over wet tundra areas our estimated alt values match in situ measurements at circumpolar active layer monitoring calm sites within uncertainties our results demonstrate that insar can provide alt estimates over large areas at high spatial resolution

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

scaling of differentially eroded surfaces in the drainage network of the ethiopian plateau differentially eroded regions selected over the ethiopian plateau northeast africa were statistically analyzed using satellite images of various electromagnetic spectrum regions and resolutions landsat tm and ers 1 the power spectrum exponent values for the landsat tm2 visible and ers 1 images over the same surface are associated to the intrinsic properties of the different sensor type and postprocessing of the data differences in the values were observed between eroded area blue nile canyon bnc and relatively noneroded area plateau pla for all data sets these differences are associated to the mechanical erosion of the plateau the remotely sensed data fields show scaling from 35 m to 15 km with no break at 1 5 km and are highly multifractal analyses of the landsat tm bands over each area demonstrated something particular values for bands in the shortwave infrared swir range differed from values for bands in the visible spectrum range in the plateau area by about 0 48 while in the drainage area this difference is around 0 13 landsat tm swir bands are sensitive to spectral signature of clay minerals while data in the visible spectrum range mostly depict topography gradients two concurrent processes are highlighted mechanical erosion and chemical erosion deposition which interact to produce the observed differences in the drainage area where cliffs and steep slopes are present and mechanical erosion intensively occurs the alteration minerals are remobilized quickly whereas in the plateau area mechanical erosion is low and alteration mineral deposition is less disturbed such new statistical highlights of topographic versus chemical surfaces will have to be taken into account in landforming models

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

rock glacier dynamics and paleoclimatic implications many rock glaciers contain massive ice that may be useful in paleoclimate studies interpreting geochemical ice core records from rock glaciers requires a thorough understanding of rock glacier structure and dynamics high precision surface velocity data were obtained for the galena creek rock glacier absaroka mountains wyoming surface velocities range from 0 to 1 00 m yr and vary across the rock glacier in a manner similar to true glaciers we used glen s flow law to calculate the thickness of the deforming ice layer the modeled ice thickness ranges from 0 to 50 m and is confirmed by direct observations this agreement shows that rock glacier movement can be entirely explained by deformation of massive ice within the rock glacier neither basal sliding nor deformation of basal debris is necessary recovered ice cores to depths of 25 m contain thin debris layers associated with summer ablation in the accumulation zone the ages of four samples of organic material removed from several debris layers inthe southern half of the rock glacier range from 200 40 to 2250 35 14c yr b p demonstrating that the rock glacier formed well before the little ice age and may contain ice dating to the middle holocene or earlier

ground motion measurement in the lake mead area nevada by differential synthetic aperture radar interferometry time series analysis probing the lithosphere rheological structure 1 we measure ground motion around the lake mead nevada using synthetic aperture radar interferometry the lake water level has fluctuated through time since impoundment in 1935 to quantify the deformation due to water level variations over the past decade and to constrain the crust and mantle rheological parameters in the lake area we analyze 241 interferograms based on 43 ers images acquired between 1992 and 2002 all interferograms have a high coherence due to arid conditions most of them show strong atmospheric artefacts tropospheric phase delays are estimated and corrected for each interferogram by analyzing the phase elevation correlation corrections are validated using data from the era40 global atmospheric reanalysis corrected interferograms are inverted pixel by pixel to solve for the time series of ground motion in the lake area temporal smoothing is added to reduce random atmospheric artefacts the observed deformation is nonlinear in time and spreads over a 50 50 km2 area we observe a 16 mm subsidence between 1995 and 1998 due to an 11 m water level increase followed by an uplift due to the water level drop after 2000 we model the deformation taking into account the loading history of the lake since 1935 a simple elastic model with parameters constrained by seismic wave velocities does not explain the amplitude of the observed motion the two layer viscoelastic model proposed by kaufmann and amelung 2000 with a mantle viscosity of 1018 pa s adjusts well the data amplitude and its spatiotemporal shape

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

solifluction rates processes and landforms a global review abstract field data on the rates of solifluction and associated parameters are compiled from the literature in an attempt to evaluate factors controlling the spatial variability in solifluction processes and landforms with special attention on the climate solifluction relationship the analyzed data originate from 46 sites over a wide range of periglacial environments from antarctic nunataks to tropical high mountains solifluction broadly defined as slow mass wasting resulting from freeze thaw action in fine textured soils involves several components needle ice creep and diurnal frost creep originating from diurnal freeze thaw action annual frost creep gelifluction and plug like flow originating from annual freeze thaw action and retrograde movement caused by soil cohesion the depth and thickness of ice lenses and freeze thaw frequency are the major controls on the spatial variation in solifluction processes near the warm margin of the solifluction affected environment diurnal freeze thaw action induces shallow but relatively rapid movement of a superficial layer 5 10 cm thick on average often creating the thin stone banked lobes typically seen on tropical high mountains in addition to diurnal movement annual frost creep and gelifluction may occur on slopes with soil climates of seasonal frost to warm permafrost dislocating a soil layer shallower than 60 cm at a rate of centimeters per year and eventually producing medium size solifluction lobes in high arctic cold permafrost regions two sided freezing can induce plug like flow of a soil mass 60 cm or thicker the correlation between process and landform suggests that the riser height of lobes is indicative of the maximum depth of movement and prevailing freeze thaw type climate change may result in new different ground freezing conditions thereby influencing the surface velocity and maximum depth of soil movement soil moisture and topography also control solifluction high moisture availability in the seasonal freezing period enhances diurnal freeze thaw action and subsequent seasonal frost heaving the latter contributes to raising the moisture content of the thawed layer and promotes gelifluction during the thawing period the slope angle defines the upper limit of the surface velocity of solifluction a diagram correlating the potential frost creep with the actual surface velocity permits an inter site comparison of the relative magnitude of solifluction components physically based modelling of periglacial slope evolution requires synthetic and more detailed field monitoring and laboratory simulations of solifluction processes

2 5 d surface deformation of m6 1 earthquake near mt iwate detected by sar interferometry the two dimensional displacement vector field on the earth s surface associated with a large earthquake near iwate volcano in japan was mapped by combining satellite radar interferometry images from two different track directions the displacement reveals not only large main ruptures but details of many small faults movement of aftershocks and volcanic earthquakes the displacements of the aftershock faults coincide with a stress field reorganized by the main earthquake that accelerated the aftershock fault movements the displacements mimic the topography suggesting that repeated movements of the same faults in the quaternary have led to the presently existing topography

visualizing and interpreting surface displacement patterns on unstable slopes using multi geometry satellite sar interferometry 2d insar abstract it is well known that satellite radar interferometry insar is capable of measuring surface displacement with a typical accuracy on the order of millimeters to centimeters however when the true deformation vector differs from the satellite line of sight los the sensitivity decreases and interpretation of insar deformation measurements becomes challenging by combining displacement data from extensive ascending and descending terrasar x datasets collected during the summer seasons of 2009 2014 we estimate two dimensional 2d insar surface displacement displacement data are decomposed into vertical and west east deformation dip and combined deformation vector and validated using global navigation satellite system gnss data we use the decomposed dataset to visualize variations in surface velocity and direction on unstable slopes in a periglacial environment with sporadic permafrost in northern norway by identifying areas with uplift and subsidence and detecting velocity changes downslope acceleration deceleration and related areas of extension and compression we are able to explain driving and controlling mechanisms and geomorphology in two rockslides and one area with solifluction landforms

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