long term ground displacement observations using insar and gnss at piton de la fournaise volcano between 2009 and 2014 abstract monitoring ground surface displacement of volcanoes over a long period of time helps improve understanding of the volcano structure dynamics and mechanisms in this paper we investigate the spatio temporal behavior of the long term displacement field at piton de la fournaise volcano la reunion island by means of x band insar and gnss time series analysis from 2009 to 2014 we propose a new correction approach based on principal component analysis to mitigate the long wavelength artifact in the interferograms over the study area our results show that most of the volcanic edifice including the central cone the eastern flank and recent lava flow fields was affected by varying degrees of ground motion more importantly a widespread sector 20 km2 affected by time dependent downward and eastward motion was observed on the eastern flank of piton de la fournaise the combined analysis of insar and gnss time series and previous studies allows us to confirm that this large mobile sector on the eastern flank underwent deformation for at least 7 years following the end of the large march april 2007 eruption including a stage of transient strain from the end of eruption to february 2011 followed by a stage of steady state strain until late 2014 several possible origins including a pre existing structural discontinuity summit stress associated with magmatism and activated fault movement are explored to explain the observed widespread long term seaward motion that is considered to be direct evidence of potential flank instability

a method for estimating ice mass loss from relative insar observations application to the vatnajokull ice cap iceland 1 we present a new method for estimating ice mass loss from glaciers and ice sheets using interferometric synthetic aperture radar insar time series data we use a linear inversion method based on observations of nearby bedrock uplift and a solution for surface loading of an elastic half space the method assumes that mass loss is focused on lower elevation terminal regions of the glacier or ice sheet and that there is an exponential decrease in thinning rate toward the higher elevation interior we apply the method to uplift rates between 1995 and 2009 near vatnajokull iceland the data reveal up to 13 mm yr relative line of sight los velocity around the south western edge of vatnajokull we find an ice mass loss rate of 6 8 0 7 0 8 gt yr in approximate agreement with other estimates ice loss since 1995 is twice as fast as the loss rate estimated for the rest of the 20th century

interseismic strain accumulation across the north anatolian fault from envisat insar measurements 1 the north anatolian fault naf is a major feature of middle eastern tectonics and several previous insar studies have measured interseismic deformation across the fault all previous studies however have used sar data acquired from a single line of sight los direction leading to large uncertainties on model parameters and necessitating several modelling assumptions to be made we have measured interseismic deformation across the naf using both ascending and descending sar data for the first time an aim that has previously been limited by the availability of ascending data by using sar data from two look directions we have been able to reduce the range of uncertainties in slip rate and locking depth from previous studies by 60 and by assuming no vertical motion across the fault we estimate both fault normal and fault parallel motion these results support other evidence for predominantly horizontal strike slip motion on the naf our data are consistent with a slip rate of 20 26 mm yr below a locking depth of 13 5 25 km for the naf

potential for larger earthquakes in the east san francisco bay area due to the direct connection between the hayward and calaveras faults the hayward and calaveras faults two strike slip faults of the san andreas system located in the east san francisco bay area are commonly considered independent structures for seismic hazard assessment we use interferometric synthetic aperture radar to show that surface creep on the hayward fault continues 15 km farther south than previously known revealing new potential for rupture and damage south of fremont the extended trace of the hayward fault also illuminated by shallow repeating micro earthquakes documents a surface connection with the calaveras fault at depths greater than 3 5 km repeating micro earthquakes located 10 km north of the surface connection highlight the 3 d wedge geometry of the junction our new model of the hayward and calaveras faults argues that they should be treated as a single system with potential for earthquake ruptures generating events with magnitudes greater than 7 posing a higher seismic hazard to the east san francisco bay area than previously considered

a quantitative assessment of dinsar measurements of interseismic deformation the southern san andreas fault case study we investigate the capabilities and limitations of the differential interferometric synthetic aperture radar dinsar techniques in particular of the small baseline subset sbas approach to measure surface deformation in active seismogenetic areas the dinsar analysis of low amplitude long wavelength deformation such as that due to interseismic strain accumulation is limited by intrinsic trade offs between deformation signals and orbital uncertainties of sar platforms in their contributions to the interferometric phases the latter being typically well approximated by phase ramps such trade offs can be substantially reduced by employing auxiliary measurements of the long wavelength velocity field we use continuous global positioning system gps measurements from a properly distributed set of stations to perform a pre filtering operation of the available dinsar interferograms in particular the gps measurements are used to estimate the secular velocity signal approximated by a spatial ramp within the azimuth range radar imaging plane the phase ramps derived from the gps data are then subtracted from the available set of dinsar interferograms this pre filtering step allows us to compensate for the major component of the long wavelength range change that within the sbas procedure might be wrongly interpreted and filtered out as orbital phase ramps with this correction the final results are obtained by simply adding the pre filtered long wavelength deformation signal to the sbas retrieved time series the proposed approach has been applied to a set of ers 1 2 sar data acquired during the 1992 2006 time interval over a 200 200 km area around the coachella valley section of the san andreas fault in southern california usa we present results of the comparison between the sbas and the line of sight los projected gps time series of the usgc pbo network as well as the mean los velocity fields derived using sbas gps and stacking techniques our analysis demonstrates the effectiveness of the presented approach and provides a quantitative assessment of the accuracy of dinsar measurements of interseismic deformation in a tectonically active area

ground surface response to continuous compaction of aquifer system in tehran iran results from a long term multi sensor insar analysis abstract most of the developed groundwater basins in iran are subject to land subsidence hazards resulting from the over extraction of groundwater several areas in tehran the capital city and a provincial center in north central iran have been reported to be subsiding at different rates in this study we present the results of an interferometric synthetic aperture radar insar time series analysis of tehran using different sar data between 2003 and 2017 by constructing more than 400 interferograms derived from 39 envisat asar c band 10 alos palsar l band 48 terrasar x x band and 64 sentinel 1 c band sar datasets we compile displacement time series from interferometric observations using the small baseline sb technique our analysis identifies 3 distinct subsidence features in tehran with rates exceeding 25 cm yr in the western tehran plain approximately 5 cm yr in the immediate vicinity of tehran international airport and 22 cm yr in the varamin plain to the southeast of tehran city the temporal pattern of land subsidence which is dominated by a decreasing trend generally follows the regional decline in groundwater level which suggests that anthropogenic processes caused by excessive groundwater extraction are the primary cause of land subsidence integrating a decadal time series of subsidence constructed from multi sensor insar with in situ observations suggests that inelastic and permanent compaction dominates the main deformation regime of the tehran aquifer and the ratio between elastic and inelastic deformation is approximately 0 4 a geological analysis indicates that the shape of the subsidence bowl in the western tehran plain does not follow the trend of major mapped faults in the region in contrast the subsidence bowl in varamin is controlled by the pishva fault which suggests that either this fault acts as a hydrologic barrier to the groundwater flow in this region or that the differences in sediment thickness causes the discontinuity in land subsidence

interseismic deformation and creep along the central section of the north anatolian fault turkey insar observations and implications for rate and state friction properties 1 we present high resolution measurements of interseismic deformation along the central section of the north anatolian fault naf in turkey using interferometric synthetic aperture radar data from the advanced land observing satellite and envisat missions we generated maps of satellite line of sight velocity using five ascending advanced land observing satellite tracks and one descending envisat track covering the naf between 31 2 e and 34 3 e the line of sight velocity reveals discontinuities of up to 5 mm yr across the ismetpasa segment of the naf implying surface creep at a rate of 9 mm yr this is a large fraction of the inferred slip rate of the naf 21 25 mm yr the lateral extent of significant surface creep is about 75 km we model the inferred surface velocity and shallow fault creep using numerical simulations of spontaneous earthquake sequences that incorporate laboratory derived rate and state friction our results indicate that frictional behavior in the ismetpasa segment is velocity strengthening at shallow depths and transitions to velocity weakening at a depth of 3 6 km the inferred depth extent of shallow fault creep is 5 5 7 km suggesting that the deeper locked portion of the partially creeping segment is characterized by a higher stressing rate smaller events and shorter recurrence interval we also reproduce surface velocity in a locked segment of the naf by fault models with velocity weakening conditions at shallow depth our results imply that frictional behavior in a shallow portion of major active faults with little or no shallow creep is mostly velocity weakening

insar bias and uncertainty due to the systematic and stochastic tropospheric delay we quantify the bias and uncertainty of interferometric synthetic aperture radar insar displacement time series and their derivatives the displacement velocities by analyzing the systematic and stochastic components of the temporal variation of the tropospheric delay the biases due to the systematic seasonal delay depend on the sar acquisition times whereas the uncertainties depend on the standard deviation of the random delay the number of acquisitions the total time span covered and the covariance of the time series of the stochastic delay between a pixel and the reference we study the contribution of the wet delay to the insar observations along the western india plate boundary using i moderate resolution imaging spectroradiometer precipitable water vapor ii stratified tropospheric delay estimated from the era i global atmospheric model and iii seven envisat insar swaths our analysis indicates that the amplitudes of the annual delay vary by up to 10 cm in this region equivalent to a maximum displacement bias of 24 cm in insar line of sight direction between two epochs assuming envisat is6 beam mode the stratified tropospheric delay correction mitigates this bias and reduces the scatter due to the stochastic delay for 7 years of envisat acquisitions along the western india plate boundary the uncertainty of the insar velocity field due to the residual stochastic wet delay after stratified tropospheric delay correction using the era i model is in the order of 2 mm yr over 100 km and 4 mm yr over 400 km we discuss the implication of the derived uncertainties on the full variance covariance matrix of the insar data

a special issue devoted to gold deposits in northern nevada part 2 carlin type deposits this is the second of two special issues of economic geology devoted to gold deposits in northern nevada readers interested in a general overview of these deposits their economic significance their context within the tectonic evolution of the region and synoptic references on each gold deposit type are directed to the preface of the first special issue john et al 2003 volume 98 issue 2 contains five papers that address regional aspects important to the genesis of gold deposits in northern nevada and five papers that present detailed studies of epithermal deposits and districts all of the regional papers are pertinent to carlin type gold deposits because they address the age of mineralization arehart et al 2003 origin and evolutionary history of the northwest striking mineral belts that localize many deposits grauch et al 2003 nature of the middle and lower crust below these mineral belts howard 2003 district to deposit scale stream sediment and lithogeochemical anomalies theodore et al 2003 and stratigraphy and structure of a district located along a northeast striking lineament peters et al 2003 the nine papers in this second special issue focus on an array of problems pertinent to genetic and exploration models for carlin type deposits in northern nevada fig 1 these investigations sort out and characterize the sequence of deformational igneous and hydrothermal events in mining districts constrain the age of mineralization map paleothermal gradients identify structures and lithologies that are preferentially mineralized ascertain processes of ore formation determine sources of ore fluid components and define fluid flow paths a common theme among these papers is inheritance whereby older features in the mineral belts influence ore formation in subsequent carlin type hydrothermal systems three types of inheritance are inferred by one or more of these investigations 1 structural inheritance where older faults are reactivated during subsequent contractional and or

multidimensional time series analysis of ground deformation from multiple insar data sets applied to virunga volcanic province summary a novel multidimensional small baseline subset msbas methodology is presented for integration of multiple interferometric synthetic aperture radar insar data sets for computation of 2 or 3 d time series of deformation the proposed approach allows the combination of all possible air borne and space borne sar data acquired with different acquisition parameters temporal and spatial sampling and resolution wave band and polarization the produced time series have improved temporal resolution and can be enhanced by applying either regularization or temporal filtering to remove high frequency noise we apply this methodology to map 2003 2010 ground deformation of the virunga volcanic province vvp north kivu democratic republic of congo the horizontal and vertical time series of ground displacement clearly identify lava compaction areas long term deformation of mt nyamuragira and 2004 2006 and 2010 pre and coeruptive deformation providing that enough sar data is available the method opens new opportunities for detecting ground motion in the vvp and elsewhere

characterizing and estimating noise in insar and insar time series with modis 1 insar time series analysis is increasingly used to image subcentimeter displacement rates of the ground surface the precision of insar observations is often affected by several noise sources including spatially correlated noise from the turbulent atmosphere under ideal scenarios insar time series techniques can substantially mitigate these effects however in practice the temporal distribution of insar acquisitions over much of the world exhibit seasonal biases long temporal gaps and insufficient acquisitions to confidently obtain the precisions desired for tectonic research here we introduce a technique for constraining the magnitude of errors expected from atmospheric phase delays on the ground displacement rates inferred from an insar time series using independent observations of precipitable water vapor from modis we implement a monte carlo error estimation technique based on multiple 100 modis based time series that sample date ranges close to the acquisitions times of the available sar imagery this stochastic approach allows evaluation of the significance of signals present in the final time series product in particular their correlation with topography and seasonality we find that topographically correlated noise in individual interferograms is not spatially stationary even over short spatial scales 10 km overall modis inferred displacements and velocities exhibit errors of similar magnitude to the variability within an insar time series we examine the modis based confidence bounds in regions with a range of inferred displacement rates and find we are capable of resolving velocities as low as 1 5 mm yr with uncertainties increasing to 6 mm yr in regions with higher topographic relief

recent advances in sar interferometry time series analysis for measuring crustal deformation abstract synthetic aperture radar sar interferometry is a technique that permits remote detection of deformation at the earth s surface and has been used extensively to measure displacements associated with earthquakes volcanic activity and many other crustal deformation phenomena analysis of a time series of sar images extends the area where interferometry can be successfully applied and also allows detection of smaller displacements through the reduction of error sources here we review recent advances in time series sar interferometry methods that further improve accuracy this is particularly important when constraining displacements due to processes with low strain rates such as interseismic deformation we include examples of improved algorithms applied to image deformation associated with the 2010 eruption of eyjafjallajokull volcano in iceland slow slip on the guerrero subduction zone in mexico and tectonic deformation in western anatolia turkey

broadscale interseismic deformation and fault slip rates in the central tibetan plateau observed using insar 1 knowledge of the number location and interseismic slip rate of crustal faults is key to our understanding of the bulk mechanics of continental deformation however at present the sparsity of geodetic velocity observations is a major limiting factor to improving our knowledge of the fault network in this study we combine long swath interferometric synthetic aperture radar insar data to form an interseismic displacement rate map of over 1000 km length spanning the central tibetan plateau our dense geodetic observations indicate that strain varies smoothly in space without major concentration at previously mapped faults discrepancy between line of sight insar and gps observations between 33 n 35 n could indicate 4 mm yr of surface uplift in this region derived strain rates are less than 5 10 8 yr 1 across the plateau at the e w left lateral kunlun fault postseismic deformation following the 2001 kokoxili earthquake results in an observed strain rate of 18 4 10 8 yr 1 across a 100 km wide zone following removal of a viscoelastic model we estimate an interseismic slip rate of 12 2 mm yr for the kunlun fault in the central tibetan conjugate fault zone the ne sw striking amdo sewa and nw se striking beng co faults have right lateral slip rates of 6 1 mm yr and 1 4 1 mm yr respectively meanwhile the ne sw striking dongqiao fault has a left lateral slip rate of 1 2 1 mm yr the low slip rates we estimate for these faults indicate that tectonic strain is more broadly distributed across the plateau interior perhaps due to the lithosphere being weak and without the abrupt strength contrasts that exist at the plateau margins

insar slip rate determination on the altyn tagh fault northern tibet in the presence of topographically correlated atmospheric delays 1 the interseismic strain across the altyn tagh fault at 85 e has been measured using 59 interferograms from 26 ers 1 2 sar acquisitions on a single track for the period 1993 2000 using an atmospheric delay correction that scales linearly with height we estimate the left lateral strike slip motion to be 11 1 5 mm yr assuming no relative vertical motion and a 15 km fault locking depth this is in agreement with sparse gps measurements the atmospheric delay corrections agree well with coarse contemporaneous modelled weather data reinforcing the importance of correcting for atmospheric delays in insar studies of interseismic strain accumulation particularly in areas of high topographic relief that strongly correlate with the expected tectonic signal we also find that in addition to the tropospheric water vapour wet delay the hydrostatic dry delay makes a significant contribution to the signal

coseismic and postseismic deformation due to the 2007 m5 5 ghazaband fault earthquake balochistan pakistan time series analysis of interferometric synthetic aperture radar data reveals coseismic and postseismic surface displacements associated with the 2007 m5 5 earthquake along the southern ghazaband fault a major but little studied fault in pakistan modeling indicates that the coseismic surface deformation was caused by 9 cm of strike slip displacement along a shallow subvertical fault the earthquake was followed by at least 1 year of afterslip releasing 70 of the moment of the main event equivalent to a m5 4 earthquake this high aseismic relative to the seismic moment release is consistent with previous observations for moderate earthquakes m 6 and suggests that smaller earthquakes are associated with a higher aseismic relative to seismic moment release than larger earthquakes

space geodetic observation of the deformation cycle across the ballenas transform gulf of california the gulf of california mexico accommodates 90 of north america pacific plate relative motion while most of this motion occurs on marine transform faults and spreading centers several fault segments in the central gulf come close to peninsular baja california here we present global positioning system and interferometric synthetic aperture radar data near the ballenas transform fault separating the peninsula from angel de la guarda island we observe interseismic motion between june 2004 and may 2009 and displacements associated with the 3 august 2009 mw 6 9 earthquake from the interseismic data we estimate a locking depth of 9 12 5 km and a slip rate of 44 9 48 1 mm yr indicating that faults east of angel de la guarda deform at negligible rates and that the ballenas transform accommodates virtually all of the relative motion between the north american plate and the baja california microplate our preferred model for coseismic slip on a finite rectangular fault plane suggests 1 3 m of strike slip displacement along a vertical rupture plane that is 60 km long and extends from the surface to a depth of 13 km in the eastern ballenas channel striking parallel to baja california north america relative plate motion these estimates agree with the seismic moment tensor and the location of the major foreshock and aftershocks and are compatible with the fault location identified from high resolution bathymetric mapping the geodetic moment is 33 higher than the seismic moment in part because some afterslip and viscous flow in the first month after the earthquake are included in the geodetic estimate coulomb stress changes for adjacent faults in the gulf are consistent with the location of smaller aftershocks following the 2009 main shock and suggest potential triggering of the 12 april 2012 mw 6 9 guaymas earthquake

potential and limits of insar to characterize interseismic deformation independently of gps data application to the southern san andreas fault system the evaluation of long wavelength deformation associated with interseismic strain accumulation traditionally relies on spatially sparse gps measurements or on high spatial resolution insar velocity fields aligned to a gps based model in this approach the insar contributes only short wavelength deformation and the two data sets are dependent thereby challenging the evaluation of the insar uncertainties and the justification of atmospheric corrections here we present an analysis using 7 years of envisat insar data to characterize interseismic deformation along the southern san andreas fault saf and the san jacinto fault sjf in southern california where the saf bifurcates onto the mission creek mcf and the banning bf fault strands we outline the processing steps for using insar alone to characterize both the short and long wavelength deformation and evaluate the velocity field uncertainties with independent continuous gps data insar line of sight los and continuous gps velocities agree within 1 2 mm yr in the study area suggesting that multiyear insar time series can be used to characterize interseismic deformation with a higher spatial resolution than gps we investigate with dislocation models the ability of this mean los velocity field to constrain fault slip rates and show that a single viewing geometry can help distinguish between different slip rate scenarios on the saf and sjf 35 km apart but multiple viewing geometries are needed to differentiate slip on the mcf and bf 12 km apart our results demonstrate that interseismic models of strain accumulation used for seismic hazards assessment would benefit from the consideration of insar mean velocity maps

interferometric synthetic aperture radar insar atmospheric correction gps moderate resolution imaging spectroradiometer modis and insar integration atmospheric effects represent one of the major limitations of repeat pass interferometric synthetic aperture radar insar in this paper gps and moderate resolution imaging spectroradiometer modis data were integrated to provide regional water vapor fields with a spatial resolution of 1 km 1 km and a water vapor correction model based on the resultant water vapor fields was successfully incorporated into the jet propulsion laboratory california institute of technology roi pac software the advantage of this integration approach is that only one continuous gps station is required within a 2030 km 1354 km modis scene application to ers 2 repeat pass data over the los angeles southern california integrated gps network scign area shows that this integration approach not only helps discriminate geophysical signals from atmospheric artifacts but also reduces water vapor effects significantly which is of great interest to a wide community of geophysicists

interseismic slip rate of the northwestern xianshuihe fault from insar data 1 the xianshuihe fault is a highly active strike slip fault system near the eastern margin of the tibetan plateau we use a multi interferogram method to construct a map of line of sight deformation rate due to interseismic strain accumulation on the northwestern xianshuihe fault from a decade of sar data acquired by the ers 1 2 and envisat satellites the rate map shows a clear deformation gradient associated with the fault but slightly offset to the northeast from the surface trace joint inversion of insar rate map and gps data using monte carlo method we estimate a slip rate of 9 12 mm yr with a locking depth of 3 6 km at the 90 confidence level the slip rate agrees with the holocene fault slip rate and the historical earthquakes our results also suggest no significant across fault extension in the future insar data from both ascending and descending orbits may further constrain the 3 d fault slip rate on this fault

gold and silver metallogeny of the south china fold belt a consequence of multiple mineralizing events abstract the south china fold belt is part of the south china block that is interpreted to be the result of multiple tectonic and magmatic events that formed a collage of accreted proterozoic and phanerozoic terranes the jurassic to early cretaceous yanshanian period 180 90 ma a time of major tectono thermal events that affected much of eastern and southeastern china is of great metallogenic importance in the fold belt this period is linked to subduction of the pacific plate beneath the eurasian continent and is manifested by voluminous volcano plutonic activity of predominantly calc alkaline affinity the distribution of gold and silver deposits in the south china fold belt indicates the presence of two distinct metallogenic provinces a region of basement uplifts which are controlled by shear zones and form neoproterozoic inliers of metamorphosed iron rich rock types defines the first province in this province orogenic lodes and volcanic related epithermal deposits represent the more significant precious metal mineralization the second province is essentially confined to a belt of yanshanian felsic intermediate volcanic and subvolcanic rocks that extends along most of the southeastern china coast in an area known as the coastal volcanic belt deposits in the coastal volcanic belt are silver and or copper rich volcanic hosted and epithermal in character the precious metal metallogeny of the south china fold belt is interpreted to have developed in at least three stages one as a result of collision events during the caledonian orogeny ca 400 ma the second during the indosinian orogeny ca 200 ma and the third during or soon after the formation of the yanshanian magmatic belt yanshanian orogeny 180 90 ma the latter was responsible for a hydrothermal event that affected large sections of the belt and its proterozoic substrate this may have resulted in the redistribution and enrichment of precious metals from preexisting orogenic gold lodes in neoproterozoic basement rocks which are now exposed as windows in zones of tectonic uplift the yanshanian hydrothermal activity was particularly widespread in the coastal volcanic belt and resulted in the formation of both low and high sulfidation epithermal gold and silver and locally copper and other base metal mineralization it is suggested that the coastal volcanic belt has greater potential for world class epithermal and porphyry deposits than previously realised

mantle flow beneath a continental strike slip fault postseismic deformation after the 1999 hector mine earthquake two recent large earthquakes in the mojave desert california the magnitude 7 3 1992 landers and magnitude 7 1 1999 hector mine earthquakes have each been followed by elevated crustal strain rates over periods of months and years geodetic data collected after the hector mine earthquake exhibit a temporally decaying horizontal velocity field and a quadrant uplift pattern opposite to that expected for localized shear beneath the earthquake rupture we interpret the origin of this accelerated crustal deformation to be vigorous flow in the upper mantle in response to the stress changes generated by the earthquake our results suggest that transient flow in the upper mantle is a fundamental component of the earthquake cycle and that the lower crust is a coherent stress guide coupling the upper crust with the upper mantle

importance of ocean tidal load corrections for differential insar large time series of interferometric synthetic aperture radar insar measurements make it possible to detect slow tectonic motions of the earth s surface on the order of millimeters per year here we illustrate the importance of correcting insar data for the effects of ground displacements due to ocean tidal loads otl these loads can cause displacement gradients greater than 3 cm per 100 km which is larger than the accuracy of insar techniques and can be a significant percentage of the measured displacement due to slow tectonic processes we demonstrate the importance of otl with predicted displacements from selected regions of tectonic interest

insar time series estimation of the ionospheric phase delay an extension of the split range spectrum technique repeat pass interferometric synthetic aperture radar insar observations may be significantly impacted by the propagation delay of the microwave signal through the ionosphere which is commonly referred to as ionospheric delay the dispersive character of the ionosphere at microwave frequencies allows one to estimate the ionospheric delay from insar data through a split range spectrum technique here we extend the existing split range spectrum technique to insar time series we present an algorithm for estimating a time series of ionospheric phase delay that is useful for correcting insar time series of ground surface displacement or for evaluating the spatial and temporal variations of the ionosphere s total electron content tec experimental results from stacks of l band sar data acquired by the alos 1 japanese satellite show significant ionospheric phase delay equivalent to 2 m of the temporal variation of insar time series along 445 km in chile a region at low latitudes where large tec variations are common the observed delay is significantly smaller with a maximum of 10 cm over 160 km in california the estimation and correction of ionospheric delay reduces the temporal variation of the insar time series to centimeter levels in chile the ionospheric delay correction of the insar time series reveals earthquake induced ground displacement which otherwise could not be detected a comparison with independent gps time series demonstrates an order of magnitude reduction in the root mean square difference between gps and insar after correcting for ionospheric delay the results show that the presented algorithm significantly improves the accuracy of insar time series and should become a routine component of insar time series analysis

bedrock displacements in greenland manifest ice mass variations climate cycles and climate change the greenland gps network gnet uses the global positioning system gps to measure the displacement of bedrock exposed near the margins of the greenland ice sheet the entire network is uplifting in response to past and present day changes in ice mass crustal displacement is largely accounted for by an annual oscillation superimposed on a sustained trend the oscillation is driven by earth s elastic response to seasonal variations in ice mass and air mass i e atmospheric pressure observed vertical velocities are higher and often much higher than predicted rates of postglacial rebound pgr implying that uplift is usually dominated by the solid earth s instantaneous elastic response to contemporary losses in ice mass rather than pgr superimposed on longer term trends an anomalous pulse of uplift accumulated at many gnet stations during an approximate six month period in 2010 this anomalous uplift is spatially correlated with the 2010 melting day anomaly

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

andean structural control on interseismic coupling in the north chile subduction zone segmentation can influence the extent of earthquake rupture and event magnitude large megathrust earthquakes result from total rupture of relatively continuous segments of the subduction interface segmentation is attributed to variations in the frictional properties of the seismogenic zone or to topographic features on the down going plate structures in the overriding plate may also influence segmentation but their importance has been dismissed here we investigate the links between interface segmentation at the north chile seismic gap and a crustal scale fault structure in the overriding plate that forms a coastal scarp of about 1 km in height we use satellite interferometric synthetic aperture radar insar and global positioning system gps data to measure interseismic surface deformation between 2003 and 2009 and compare the deformation with rupture extent during well documented earthquakes from these data we infer the degree of coupling and segmentation at depth we find that along a 500 km long segment the base of the strongly coupled seismogenic zone correlates with the line of the surface coastal scarp and follows the outline of the mejillones peninsula this correlation implies that large scale structures in the overriding plate can influence the frictional properties of the seismogenic zone at depth we therefore suggest that the occurrence of megathrust earthquakes in northern chile is controlled by the surface structures that build andean topography

interseismic megathrust coupling beneath the nicoya peninsula costa rica from the joint inversion of insar and gps data the nicoya peninsula costa rica was struck by a long anticipated and gap filling mw 7 6 earthquake in 2012 to study interseismic strain accumulation on the megathrust beneath the nicoya peninsula we present an improved interseismic coupling model by integrating interferometric synthetic aperture radar insar and gps data our model reveals three strongly coupled patches the first strongly coupled patch locates beneath the nicoya peninsula and ruptured during the 2012 earthquake the second strongly coupled patch locates offshore the central nicoya peninsula and remained largely unbroken however this region is close to and possibly intermingled with shallow slow slip and tremor suggesting that accumulated strain in this region may be released both seismically and aseismically the third strongly coupled patch offshore of the southeastern end of nicoya overlaps part of the coseismic rupture of the 1990 mw 7 0 nicoya gulf earthquake indicating that significant strain has re accumulated since this event incorporating insar data provides a more refined interseismic coupling model than using gps alone and allows for a more reliable comparison with local seismic and aseismic activities this comparison indicates that strongly locked regions during the interseismic stage are the loci of coseismic slip and deep slow slip and low frequency earthquakes occur in regions of low coupling or transition zones from low to high coupling while shallow slow slip and tremor commingle with strongly coupled regions our study demonstrates that insar data can be used to recover small long wavelength deformation signals with refined resolution in challenging subduction zone environments when integrated with gps observations

geology and geochemistry of the adjacent changkeng gold and fuwang silver deposits guangdong province south china the changkeng au and fuwang ag deposits represent an economically significant and distinct member of the au ag deposit association in china the two deposits are immediately adjacent but the au and ag orebodies separated from each other ores in the au deposit located at the upper stratigraphic section and in the southern parts of the orefield contain low ag contents 11 ppm the ag orebodies in the lower stratigraphic section are au poor 0 2 ppm changkeng is hosted in brecciated cherts and jasperoidal quartz and is characterized by disseminated ore minerals fuwang hosted in the lower carboniferous zimenqiao group bioclastic limestone has vein and veinlet mineralization associated with alteration comprised of quartz carbonate sericite and sulfides homogenization temperatures of fluid inclusions from quartz veinlets in the changkeng and fuwang deposits are in the range of 210 80 c and 230 50 degrees c respectively salinities of fluid inclusions from the two deposits range from 1 6 to 7 3 wt and 1 6 to 2 6 wt equiv nacl respectively the 8d h2 o delta oh2o o 18 delta c 13 co2 and he 3 he 4 values of the fluid inclusions from the changkeng deposit range from 80 to 30 7 8 to 3 0 16 6 to 17 0 and 0 0100 to 0 0054 ra respectively the delta dh2o delta oh2o o 18 delta c 13 co2 and he 3 he 4 values of fluid inclusions from the fuwang deposit range from 59 to 45 0 9 to 4 1 6 7 to 0 6 and 0 5930 to 0 8357 ra respectively the delta dh2o delta oh2o o 18 delta c 13 co2 and he 3 he 4 values of the fluid inclusions suggest the ore fluids of the changkeng au ore come from the meteoric water and the ore fluids of the fuwang ag ore are derived from mixing of magmatic water and meteoric water the two deposits also show different pb isotopic signatures the changkeng deposit has pb isotope ratios pb 206 pb 204 18 580 to 19 251 pb 207 pb 204 15 672 to 15 801 pb 208 pb 204 38 700 to 39 104 similar to those pb 206 pb 204 18 578 to 19 433 pb 207 pb 204 15 640 to 15 775 pb 208 pb 204 38 925 to 39 920 of its host rocks and different from those pb 206 pb 204 18 820 to 18 891 pb 207 pb 204 15 848 to 15 914 pb 208 pb 204 39 579 to 39 786 of the fuwang deposit the different signatures indicate different sources of ore forming material rb sr isochron age 68 6 ma and ar 40 ar 39 age 64 3 0 1 ma of the ore related quartz veins from the ag deposit indicate that the fuwang deposit formed during the cenozoic himalayan tectonomagmatic event crosscutting relationships suggests that au ore predates ag ore the adjacent changkeng and fuwang deposits could however represent a single evolved hydrothermal system the ore fluids initially deposited au in the brecciated siliceous rocks and then mixing with the magmatic water resulted in ag deposition within fracture zones in the limestone the deposits are alternatively the product of the superposition of two different geological events age evidence for the fuwang deposit together with the xiqiaoshan tertiary volcanic hosted ag deposit in the same area indicates that the pacific coasaal volcanic belt in the south china fold belt has greater potiental for himalayan precious metal mineralization than previous realized c elsevier b v all rights reserved

iceland rising solid earth response to ice retreat inferred from satellite radar interferometry and visocelastic modeling a broad uplift occurs in iceland in response to the retreat of ice caps which began circa 1890 until now this deformation signal has been measured primarily using gps at points some distance away from the ice caps here for the first time we use satellite radar interferometry interferometric synthetic aperture radar to constrain uplift of the ground all the way up to the edge of the largest ice cap vatnajokull this allows for improved constraints on the earth rheology both the thickness of the uppermost earth layer that responds only in an elastic manner and the viscosity below it the interferometric synthetic aperture radar velocities indicate a maximum displacement rate of 24 4 and 31 4 mm yr at the edge of vatnajokull during 1995 2002 and 2004 2009 respectively the fastest rates occur at outlet glaciers of low elevation where ice retreat is high we compare the observations with glacial isostatic adjustment models that include the deglaciation history of the icelandic ice caps since 1890 and two earth layers using a bayesian approach we derived probability density functions for the average earth model parameters for three satellite tracks based on our assumptions the three best fit models give elastic thicknesses in the range of 15 40 km and viscosities ranging from 4 10 1018 pa s

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

interseismic and postseismic shallow creep of the north qaidam thrust faults detected with a multitemporal insar analysis understanding the mechanisms by which earthquake cycles produce folding and accommodate shortening is essential to quantify the seismic potential of active faults and integrate aseismic slip within our understanding of the physical mechanisms of the long term deformation however measuring such small deformation signals in mountainous areas is challenging with current space geodesy techniques due to the low rates of motion relative to the amplitude of the noise here we successfully carry out a multitemporal interferometric synthetic aperture radar analysis over the north qaidam fold thrust system in ne tibet where eight mw 5 2 earthquakes occurred between 2003 and 2009 we report various cases of aseismic slip uplifting the thickened crust at short wavelengths we provide a rare example of a steep shallow 13 km long and 6 km wide afterslip signal that coincides spatially with an anticline and that continues into 2011 in response to a mw 6 3 event in 2003 we suggest that a buried seismic slip during the 2003 earthquake has triggered both plastic an elastic folding and aseismic slip on the shallow thrusts we produce a first order two dimensional model of the postseismic surface displacements due to the 2003 earthquake and highlight a segmented slip on three fault patches that steepen approaching the surface this study emphasizes the fundamental role of shallow aseismic slip in the long term and permanent deformation of thrusts and folds and the potential of interferometric synthetic aperture radar for detecting and characterizing the spatiotemporal behavior of aseismic slip over large mountainous regions

accelerating uplift in the north atlantic region as an indicator of ice loss vertical motions of the rocky margins of greenland and antarctica respond to mass changes of their respective ice sheets but these motions can be obscured by ancient episodes of glacial advance or retreat an analysis of the acceleration of vertical motion indicates that accelerated ice loss in western greenland started in the late 1990s vertical motions of the rocky margins of greenland and antarctica respond to mass changes of their respective ice sheets1 2 however these motions can be obscured by episodes of glacial advance or retreat that occurred hundreds to thousands of years ago3 4 5 6 which trigger a delayed response because of viscous flow in the underlying mantle here we present high precision global positioning system gps data that describe the vertical motion of the rocky margins of greenland iceland and svalbard we focus on vertical accelerations rather than velocities to avoid the confounding effects of past events our data show an acceleration of uplift over the past decade that represents an essentially instantaneous elastic response to the recent accelerated melting of ice throughout the north atlantic region our comparison of the gps data to models for glacial isostatic adjustment suggests that some parts of western coastal greenland were experiencing accelerated melting of coastal ice by the late 1990s using a simple elastic model we estimate that western greenland s ice loss is accelerating at an average rate of 8 7 3 5 gt yr 2 whereas the rate for southeastern greenland based on limited data falls at 12 5 5 5 gt yr 2

interseismic coupling and refined earthquake potential on the hayward calaveras fault zone interseismic strain accumulation and fault creep is usually estimated from gps and alignment arrays data which provide precise but spatially sparse measurements here we use interferometric synthetic aperture radar to resolve the interseismic deformation associated with the hayward and calaveras faults hf and cf in the east san francisco bay area the large 1992 2011 sar data set permits evaluation of short and long wavelength deformation larger than 2 mm yr without alignment of the velocity field to a gps based model our time series approach in which the interferogram selection is based on the spatial coherence enables deformation mapping in vegetated areas and leads to refined estimates of along fault surface creep rates creep rates vary from 0 2 mm yr on the northern cf to 14 2 mm yr on the central cf south of the hf surface junction we estimate the long term slip rates by inverting the long wavelength deformation and the distribution of shallow slip due to creep by inverting the remaining velocity field this distribution of slip reveals the locations of locked and slowly creeping patches with potential for a m6 8 0 3 on the hf near san leandro a m6 6 0 2 on the northern cf near dublin a m6 5 0 1 on the hf south of fremont and a m6 2 0 2 on the central cf near morgan hill with cascading multisegment ruptures the hf rupturing from berkeley to the cf junction could produce a m6 9 0 1 the northern cf a m6 6 0 1 the central cf a m6 9 0 2 from the junction to gilroy and a joint rupture of the hf and central cf could produce a m7 1 0 1

southern san andreas san jacinto fault system slip rates estimated from earthquake cycle models constrained by gps and interferometric synthetic aperture radar observations we use ground geodetic and interferometric synthetic aperture radar satellite observations across the southern san andreas saf san jacinto sjf fault systems to constrain their slip rates and the viscosity structure of the lower crust and upper mantle on the basis of periodic earthquake cycle maxwell viscoelastic finite element models key questions for this system are the saf and sjf slip rates the slip partitioning between the two main branches of the sjf and the dip of the saf the best fitting models generally have a high viscosity lower crust 10 21 pa s overlying a lower viscosity upper mantle 10 19 pa s we find considerable trade offs between the relative time into the current earthquake cycle of the san jacinto fault and the upper mantle viscosity with reasonable assumptions for the relative time in the earthquake cycle the partition of slip is fairly robust at around 24 26 mm a for the san jacinto fault system and 16 18 mm a for the san andreas fault models for two subprofiles across the saf sjf systems suggest that slip may transfer from the western coyote creek branch to the eastern clark superstition hills branch of the sjf from nw to se across the entire system our best fitting model gives slip rates of 2 3 12 9 12 9 and 17 3 mm a for the elsinore coyote creek clark and san andreas faults respectively where the large uncertainties in the slip rates for the sjf branches reflect the large uncertainty in the slip rate partitioning within the sjf system

dem error correction in insar time series we present a mathematical formulation for the phase due to the errors in digital elevation models dems in synthetic aperture radar sar interferometry insar time series obtained by the small baseline sb or the small baseline subset method we show that the effect of the dem error in the estimated displacement is proportional to the perpendicular baseline history of the set of sar acquisitions this effect at a given epoch is proportional to the perpendicular baseline between the sar acquisition at that epoch and the reference acquisition therefore the dem error can significantly affect the time series results even if sb interferograms are used we propose a new method for dem error correction of insar time series which operates in the time domain after inversion of the network of interferograms for the displacement time series this is in contrast to the method of berardino 2002 in which the dem error is estimated in the interferogram domain we show the effectiveness of this method using simulated insar data we apply the new method to fernandina volcano in the galapagos islands and show that the proposed dem error correction improves the estimated displacement significantly

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

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

multi interferogram method for measuring interseismic deformation denali fault alaska summary studies of interseismic strain accumulation are crucial to our understanding of continental deformation the earthquake cycle and seismic hazard by mapping small amounts of ground deformation over large spatial areas insar has the potential to produce continental scale maps of strain accumulation on active faults however most insar studies to date have focused on areas where the coherence is relatively good e g california tibet and turkey and most analysis techniques stacking small baseline subset algorithm permanent scatterers etc only include information from pixels which are coherent throughout the time span of the study in some areas such as alaska where the deformation rate is small and coherence very variable it is necessary to include information from pixels which are coherent in some but not all interferograms we use a three stage iterative algorithm based on distributed scatterer interferometry we validate our method using synthetic data created using realistic parameters from a test site on the denali fault alaska and present a preliminary result of 10 5 5 0 mm yr 1 for the slip rate on the denali fault based on a single track of radar data from ers1 2

calibrating interferometric synthetic aperture radar insar images with regional gps network atmosphere models summary interferometric synthetic aperture radar insar technology provides a valuable tool for obtaining earth surface deformation and topography at high spatial resolution for crustal deformation studies similar to global positioning system gps insar measurements are affected by the earth s ionospheric and tropospheric layers as the electromagnetic signals significantly refract while propagating through the different layers while gps signals propagating through the neutral atmosphere are affected primarily by the distribution pressure and temperature of atmospheric gases including water vapour the propagation through the ionosphere is mainly affectedbythenumberoffreeelectronsalongthesignalpath here wepresenttheuseofdense regional gps networks for extracting tropospheric zenith delays and ionospheric total electron content tec maps in order to reduce the noise levels in insar images the results show significant reduction in the root mean square rms values when simultaneously combining the two corrections both at short time periods where no surface deformation is expected and at longer periods where imaging of localized subsidence and fault creep is enhanced

the 2016 m7 kumamoto japan earthquake slip field derived from a joint inversion of differential lidar topography optical correlation and insar surface displacements

brief duration of hydrothermal activity at round mountain nevada determined from ar 40 ar 39 geochronology the round mountain gold silver deposit is one of the world s largest volcanic hosted precious metal deposits reserves plus production total at least 16 million oz 500 000 kg au the deposit occurs in ash flow tuff that is ponded within its source caldera along and overlying the caldera ring fracture host rocks have undergone propylitic potassic and high level silicic and intermediate argillic alteration these are interpreted either as a temporal sequence from early propylitic to late silicic and argillic or as a spatial progression from a potassic core outward to a propylitic halo 40 ar 39 ar ages determined by single crystal fusion of sanidine from host tuff and incremental heating of adularia indicate a most likely duration of hydrothermal activity of approximately 0 1 m y possibly no more than 0 05 m y and a maximum of 0 5 m y eruption of host ash flow tuff and caldera collapse occurred at 26 5 ma a late or postalteration tuff that rests upon mineralized rock is 26 0 ma hydrothermal circulation is unlikely to have been established immediately after caldera collapse so duration was probably considerably less than 0 5 m y eight adularia samples give ages between 25 94 or 0 09 and 26 09 or 0 05 ma and one is 26 20 or 0 05 ma the mean of all nine is 26 03 or 0 08 ma the maximum and minimum values and their uncertainties allows a duration of as much as 0 4 m y but for the following reasons the longevity is probably much less the absolute ages of seven samples that can be placed in the possible temporal alteration sequence do not correlate with that sequence this does not disprove the temporal sequence but does indicate that alteration occurred in a time span which is not resolvable even with precise 40 ar 39 ar dating furthermore all samples show flat age spectra which themselves argue against a long continuously active system kinetic studies of two adularia reveal diffusion domains with ar closure temperatures between approximately 230 degrees and approximately 390 degrees c adularia that crystallized and remained at temperatures of 275 degrees c the maximum temperature inferred from fluid inclusion data would yield age spectra with age gradients spanning the lifetime of the system no spectra are consistent with a thermal history that incorporates sustained 0 1 m y temperatures at or above 275 degrees c episodic activity to account for the one older adularia date cannot be precluded but is inconsistent with most data therefore the hydrothermal system probably was active for less than the uncertainty in the ages of individual samples possibly as little as 50 000 years we conclude that hydrothermal activity at round mountain was a brief event at approximately 26 0 ma and was closely linked to caldera structure and magmatism this activity followed initial ash flow eruption by 0 5 m y and may have been driven by a ring fracture intrusion

insar observations of strain accumulation and fault creep along the chaman fault system pakistan and afghanistan we use 2004 2011 envisat synthetic aperture radar imagery and insar time series methods to estimate the contemporary rates of strain accumulation in the chaman fault system in pakistan and afghanistan at 29 n we find long term slip rates of 16 2 3 mm yr for the ghazaband fault and of 8 3 1 mm yr for the chaman fault this makes the ghazaband fault one of the most hazardous faults of the plate boundary zone we further identify a 340 km long segment displaying aseismic surface creep along the chaman fault with maximum surface creep rate of 8 1 2 mm yr the observation that the chaman fault accommodates only 30 of the relative plate motion between india and eurasia implies that the remainder is accommodated south and east of the katawaz block microplate

origin of high grade gold ore source of ore fluid components and genesis of the meikle and neighboring carlin type deposits northern carlin trend nevada the meikle mine exploits one of the world s highest grade carlin type gold deposits with reserves of ca 220 t gold at an average grade of 24 7 g t locally gold grades exceed 400 g t several geologic events converged at meikle to create these spectacular gold grades prior to mineralization a devonian hydrothermal system altered the bootstrap limestone to fe rich dolomite subsequently the rocks were brecciated by faulting and late jurassic intrusive activity the resulting permeability focused flow of late eocene carlin type ore fluids and allowed them to react with the fe rich dolomite fluid inclusion data and mineral assemblages indicate that these fluids were hot ca 220 c of moderate salinity 2 s rich gold rich pyrite formed by dissolution of dolomite and sulfidation of its contained fe where dissolution and replacement were complete ore stage pyrite and other insoluble minerals were all that remained locally these minerals accumulated as internal sediments in dissolution cavities to form ore with gold grades 400 g t petrographic observations geochemical data and stable isotope results from the meikle mine and other deposits at the goldstrike mine place important constraints on genetic models for meikle and other carlin type gold deposits on the northern carlin trend the ore fluids were meteoric water d 135 18 o 5 that interacted with sedimentary rocks at a water rock ratio of ca 1 and temperatures of ca 220 c the absence of significant silicification suggests that there was little cooling of the ore fluids during mineralization these two observations strongly suggest that ore fluids were not derived from deep sources but instead flowed parallel to isotherms the gold was transported by h 2 s 34 s 9 which was derived from paleozoic sedimentary rocks the presence of auriferous sedimentary exhalative mineralization in the local stratigraphic sequence raises the possibility that preexisting concentrations of gold contributed to the carlin type deposits taken together our observations suggest that meteoric water evolved to become an ore fluid by shallow circulation through previously gold and sulfur enriched rocks carlin type gold deposits formed where these fluids encountered permeable reactive fe rich rocks

subsidence at southern andes volcanoes induced by the 2010 maule chile earthquake large earthquakes in subduction zones can affect nearby volcanoes analysis of ground deformation following the 2010 earthquake in maule chile shows that some volcanoes subsided by up to 15 cm probably because of quake triggered release of hydrothermal fluids

monitoring of active tectonic deformations in the longitudinal valley eastern taiwan using persistent scatterer insar method with alos palsar data abstract this paper presents new observation of the interseismic deformation along the longitudinal valley eastern taiwan that represents a major tectonic boundary of the taiwan collision zone we investigate the southern part of the valley from rueisuei to taitung latitude 23 5 n 22 7 n which is the part of the valley where interseismic surface creep has already been observed at some points of the longitudinal valley fault lvf a persistent scatterer sar interferometry approach stamps is applied using ten l band sar images from alos satellite acquired over the period 2007 2010 interferograms from l band data show a dramatic improvement of coherence in comparison to previous studies using c band ers data the density of measurement resulting from stamps processing is the highest achieved so far in the area about 40 55 points per km2 for a total of 77 000 points allowing a continuous view of the deformation along the valley and also giving information on its borders central range and coastal range the most striking feature of the resulting mean velocity map is a clear velocity discontinuity localized in a narrow band 0 1 1 km along the lvf and responsible for up to 3 cm yr velocity offset along the radar line of sight which is attributed to shallow interseismic creep insar results are in good agreement with continuous gps measurements over the same period 0 3 cm yr rms the density of measurement allows us to improve fault trace map along the creeping section of the lvf with accuracy of about 100 m and to find new field evidences of the fault activity in some places our trace differs significantly hundreds of meters from previous published traces the creep rate shows significant variations along the fault at the southern end of the valley the deformation is distributed on several structures including the luyeh strand and drops significantly south of the peinanshan however there are discrepancies with previous studies made from ers data over the period 1993 1999 that remain to be investigated the mean velocity for each point of measure and the improved faults trace are provided as supplementary data

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

some thoughts on the use of insar data to constrain models of surface deformation noise structure and data downsampling repeat pass interferometric synthetic aperture radar insar provides spatially dense maps of surface deformation with potentially tens of millions of data points here we estimate the actual covariance structure of noise in insar data we compare the results for several independent interferograms with a large ensemble of gps observations of tropospheric delay and discuss how the common approaches used during processing of insar data affects the inferred covariance structure motivated by computational concerns associated with numerical modeling of deformation sources we then combine the data covariance information with the inherent resolution of an assumed source model to develop an efficient algorithm for spatially variable data resampling or averaging we illustrate these technical developments with two earthquake scenarios at different ends of the earthquake magnitude spectrum for the larger events our goal is to invert for the coseismic fault slip distribution for smaller events we infer the hypocenter location and moment we compare the results of inversions using several different resampling algorithms and we assess the importance of using the full noise covariance matrix

fifteen years of surface deformation in western taiwan insight from sar interferometry abstract geodetically measured surface displacements are produced by a combination of underlying deformation processes acting at different spatial and temporal scales a complete history of surface measurements in an area can help discriminate contributions from tectonic hydrologic and anthropogenic processes in this study we use synthetic aperture radar sar images of the active mountain front and adjacent coastal plain of southwestern taiwan to generate time series of surface deformation from 1995 to 2001 and from 2005 to 2008 based on the insar small baseline method the insar measurements agree well with los motions estimated from continuous gps measurements of 3d displacements between 2006 and 2008 a significant range increase in line of sight los is dominated by land subsidence in the coastal area of western and southwestern taiwan subsidence rates vary with annual periods and are highly correlated with seasonal precipitation which are likely associated with groundwater recharge and withdrawal the long term deformation is dominated by long term tectonic loading in sw taiwan during the interseismic period of the earthquake cycle including elastic strain along or continuous creep on the active faults our results show the ability of insar to reveal spatiotemporal crustal deformation in western taiwan with high spatial resolution and accuracy which is potentially important for evaluating seismic hazards

bulk mineralogy of lunar crater central peaks via thermal infrared spectra from the diviner lunar radiometer a study of the moon s crustal composition at depth 1 the central peaks of lunar impact craters are thought to be composed of uplifted material originating from varying depths of the crustal column the interpreted crystallization sequence of the early lunar magma ocean resulted in an anorthositic upper crust that may become progressively more mafic as it approaches the olivine rich mantle emissivity spectra from the lunar reconnaissance orbiter lro diviner radiometer are used to derive the wavelength location of the christiansen feature cf which is sensitive to bulk silicate mineralogy here a survey of cf values has been performed for the central peaks of 135 complex craters providing global and regional observations of the heterogeneity of crustal compositions crustal thickness models give context to the preimpact depth of the central peak material and its proximity to the crust mantle boundary this study has identified six craters with potentially ultramafic compositions within their central peaks more common occurrences of mafic material found in a wide variety of crater central peaks show a silicate composition roughly similar to mare basalt or an olivine bearing gabbro the range of central peak cf values is similar to that of the rest of the lunar surface bulk mineralogy of the central peak material does not appear to be correlated with its crustal depth of origin suggesting both lateral and vertical heterogeneity in crustal composition rather than a gradual transition from felsic to mafic composition it is likely that the moon s extensive cratering history has continually overturned the original crust erasing any original systematic dependence of composition on depth or proximity to the mantle

delamination wedge structure beneath the hidaka collision zone central hokkaido japan inferred from seismic reflection profiling in the hidaka collision zone of hokkaido northern japan the kuril island arc collides with the northeast japan arc in order to better understand the collision process new high resolution information about lithospheric structure was obtained by means of a series of seismic reflection surveys these seismic profiles reveal distinct zones of seismic lamination in the lower crust of the kuril arc the upper portion of the lower crust is characterized by numerous east dipping reflectors in contrast west dipping reflectors dominate the lower part of the lower crust from this reflector configuration the lower crust of the kuril arc is interpreted to be delaminated by the collision the geometry of delamination is consistent with other geophysical data as well as the peak metamorphic grades exposed in the hidaka mountains as earthquakes indicate that delamination here is ongoing the hidaka collision zone represents an active model for continental growth by arc accretion with delamination of lower arc crust

tectonic control of subsidence and southward displacement of southeast louisiana with respect to stable north america 1 gps data collected between 1995 and 2006 suggest that southeast louisiana including new orleans and the larger mississippi delta are both subsiding vertically and moving southward with respect to stable north america both motions are likely related due to their common tectonic setting subsidence in the new orleans area occurs in part because it is located in the hanging wall of a large listric normal fault system that forms the northern boundary of a 7 10 km thick allochthon that is detached from stable north america southward motion of this allochthon relative to stable north america occurs at 2 2 0 6 mm yr the average subsidence rate for gps sites located on the allochthon is 5 2 0 9 mm yr relative to earth s center of mass or 7 mm yr relative to mean sea level motion of the allochthon is likely due to the gravity instability created by rapid holocene sediment deposition in the delta following continental glacial retreat and is facilitated at depth by weak salt horizons because new orleans and other communities of southeastern louisiana lie atop this active allochthon future motion of this body should be considered during rebuilding of the region following hurricanes katrina and rita

ground surface deformation patterns magma supply and magma storage at okmok volcano alaska from insar analysis 1 intereruption deformation 1997 2008 eruption magma storage had increased by 3 7 5 2 1 0 7 m 3 or 85 100 of the 1997 eruption volume we propose that the supply rate decreased in response to the diminishing pressure gradient between the shallow storage zone and a deeper magma source region eventuallytheeffectsofcontinuingmagmasupplyandvesiculationofstoredmagmacaused acriticalpressurethresholdtobeexceeded triggeringthe2008eruption asimilarpatternof initially rapid inflation followed by oscillatory but generally slowing inflation was observed prior to the 1997 eruption in both cases withdrawal of magma during the eruptions depressurized the shallow storage zone causing significant volcano wide subsidence and initiating a new intereruption deformation cycle

sedimentary rock hosted au deposits of the dian qian gui area guizhou and yunnan provinces and guangxi district china abstract sedimentary rock hosted au deposits in the dian qian gui area in southwest china are hosted in paleozoic and early mesozoic sedimentary rocks along the southwest margin of the yangtze south china precambrian craton most deposits have characteristics similar to carlin type au deposits and are spatially associated on a regional scale with deposits of coal sb barite as tl and hg sedimentary rock hosted au deposits are disseminated stratabound and or structurally controlled the deposits have many similar characteristics particularly mineralogy geochemistry host rock and structural control most deposits are associated with structural domes stratabound breccia bodies unconformity surfaces or intense brittle ductile deformation zones such as the youjiang fault system typical characteristics include impure carbonate rock or calcareous and carbonaceous host rock that contains disseminated pyrite marcasite and arsenopyrite usually with m sized au commonly in as rich rims of pyrite and in disseminations late realgar orpiment stibnite and hg minerals are spatially associated with earlier forming sulfide minerals minor base metal sulfides such as galena sphalerite chalcopyrite and pb sb as sulphosalts also are present the rocks locally are silicified and altered to sericite clay illite rocks and or stream sediment geochemical signatures typically include elevated concentrations of as sb hg tl and ba a general lack of igneous rocks in the dian qian gui area implies non pluton related ore forming processes some deposits contain evidence that sources of the metal may have originated in carbonaceous parts of the sedimentary pile or other sedimentary or volcanic horizons this genetic process may be associated with formation and mobilization of petroleum and hg in the region and may also be related to as au and tl bearing coal horizons many deposits also contain textures and features indicative of strong structural control by tectonic domes or shear zones and also suggest syndeformational ore deposition possibly related to the youjiang fault system several sedimentary rock hosted au deposits in the dian qian gui area also are of the red earth type and au grades have been concentrated and enhanced during episodes of deep weathering

persistent scatterer interferometry analysis of ground deformation in the po plain piacenza reggio emilia sector northern italy seismo tectonic implications

impact of anthropogenic subsidence on relative sea level rise in the fraser river delta subsidence is a common cause of amplified relative sea level rise flooding and erosion in coastal environments in particular subsidence due to sediment consolidation can play a significant role in relative sea level rise in large deltas we use a combination of insar interferometric synthetic aperture radar leveling and global positioning system data to map absolute vertical land motion in the fraser river delta western canada we show that primary consolidation of shallow holocene sediments is the main cause for the slow subsidence 1 to 2 mm a affecting the delta lowlands in addition parts of the delta undergo increased anthropogenic subsidence rapid subsidence rates 3 to 8 mm a are associated with recent artificial loads and exhibit a first order exponential decrease with a time constant of 20 years consistent with the theory of consolidation assuming two sea level rise scenarios of 30 or 100 cm by the end of the twenty first century natural subsidence will augment relative sea level rise in the fraser holocene lowlands by 50 or 15 anthropogenic subsidence will augment relative sea level rise by 130 or 40 potentially raising it to as much as 1 2 m in deltaic lacustrine and alluvial environments anthropogenic sediment consolidation can result in significant amplification and strong spatial variations of relative sea level rise that need to be considered in local planning

space geodesy subsidence and flooding in new orleans a subsidence map of the city offers insight into the failure of the levees during hurricane katrina

the tuscarora au ag district eocene volcanic hosted epithermal deposits in the carlin gold region nevada the tuscarora mining district contains the oldest and the only productive eocene epithermal deposits in nevada the district is a particularly clear example of association of low sulfidation deposits with igneous activity and structure and it is unusual in that it consists of two adjoining but physically and chemically distinct types of low sulfidation deposits moreover tuscarora deposits are of interest because they formed contemporaneously with nearby giant carlin type gold deposits the tuscarora deposits formed within the 39 9 to 39 3 ma tuscarora volcanic field along and just outside the southeastern margin of the caldera like mount blitzen volcanic center both deposit types formed at 39 3 ma contemporaneous with the only major intrusive activity in the volcanic field no deposits are known to have formed during any of the intense volcanic phases of the field intrusions were the apparent heat source and structures related to the mount blitzen center were conduits for hydrothermal circulation the ore forming fluids interacted dominantly with eocene igneous rocks the two deposit types occur in a northern silver rich zone that is characterized by relatively high ag au ratios 110 150 narrow alteration zones and quartz and carbonate veins developed mostly in intrusive dacite and in a southern gold rich zone that is typified by relatively low ag au ratios 4 14 more widespread alteration and quartz fissure and stockwork veins commonly developed in tuffaceous sedimentary rocks the deposit types have similar fluid inclusion and pb and s isotope characteristics but different geochemical signatures quartz veins from both zones have similar thermal and paragenetic histories and contain fluid inclusions that indicate that fluids cooled from between 260 and 230 c to less than 200 c fluid boiling may have contributed to precious metal deposition veins in both zones have relatively high as and sb and low bi te and w the silver zone has high ca pb mn zn cd tl and se the gold zone has high hg and mo a few samples from an area of overlap between the two zones share chemical characteristics of both deposit types the deposit types could represent a single zoned or evolving system in which hydrothermal fluids rose along structures within the silver zone preferentially deposited ag and base metals and then spread into the gold zone alternatively the deposit types could represent two distinct but temporally indistinguishable hydrothermal cells that only narrowly overlapped spatially as noted in previous studies the hydrothermal fluids that generated the tuscarora and other epithermal deposits could have evolved from carlin type fluids by boiling and mixing with meteoric water if so the tuscarora deposit may represent epithermal conditions above carlin type deposits and carlin type deposits may lie beneath the district

rapid strain accumulation on the ashkabad fault turkmenistan from atmosphere corrected insar 1 we have measured interseismic deformation across the ashkabad strike slip fault using 13 envisat interferograms covering a total effective timespan of 30 years atmospheric contributions to phase delay are significant and variable due to the close proximity of the caspian sea in order to retrieve the pattern of strain accumulation we show it is necessary to use data from envisat s medium resolution imaging spectrometer meris instrument as well as numerical weather model outputs from the european centre for medium range weather forecasts ecmwf to correct interferograms for differences in water vapor and atmospheric pressure respectively this has enabled us to robustly estimate the slip rate and locking depth for the ashkabad fault using a simple elastic dislocation model our data are consistent with a slip rate of 5 12 mm yr below a locking depth of 5 5 17 km for the ashkabad fault and synthetic tests support the magnitude of the uncertainties on these estimates our estimate of slip rate is 1 25 6 times higher than some previous geodetic estimates with implications for both seismic hazard and regional tectonics in particular supporting fast relative motion between the south caspian block and eurasia this result reinforces the importance of correcting for atmospheric contributions to interferometric phase for small strain measurements we also attempt to validate a recent method for atmospheric correction based on ecmwf era interim model outputs alone and find that this technique does not work satisfactorily for this region when compared to the independent meris estimates

postseismic mantle relaxation in the central nevada seismic belt holocene acceleration of deformation and postseismic relaxation are two hypotheses to explain the present day deformation in the central nevada seismic belt cnsb discriminating between these two mechanisms is critical for understanding the dynamics and seismic potential of the basin and range province interferometric synthetic aperture radar detected a broad area of uplift 2 to 3 millimeters per year that can be explained by postseismic mantle relaxation after a sequence of large crustal earthquakes from 1915 to 1954 the results lead to a broad agreement between geologic and geodetic strain indicators and support a model of a rigid basin and range between the cnsb and the wasatch fault

interferometric synthetic aperture radar gps integration interseismic strain accumulation across the hunter mountain fault in the eastern california shear zone 1 the principal limitations of interferometric synthetic aperture radar insar to measure subtle long wavelength deformation are uncertainties associated with the satellite orbits we propose a method to remove orbital phase errors from the insar data by integrating insar and continuous gps time series we model the along track variation of the baseline errors as second order polynomials and estimate the coefficients using the continuous gps measurements we apply this method to a 600 km long region encompassing the basin and range and the eastern california shear zone comparison of the corrected insar velocities with independent gps data shows that this method removes the long wavelength insar errors the insar data reveal a region of sharp variation in the line of sight velocity across the hunter mountain fault we model the deformation as interseismic elastic strain accumulation across a strike slip fault the modeling suggests a fault slip rate of 4 9 0 8 mm yr and a locking depth of 2 0 4 km the shallow locking depth suggests that the hunter mountain fault is a transfer fault between low angle normal faults in the area

classification of slope processes based on multitemporal dinsar analyses in the himalaya of nw bhutan abstract slope deformation in mountainous terrain can be driven by different processes the nature of which is either gravitational and irreversible or seasonal and reversible the latter induced by permafrost variations or by hydromechanical or thermomechanical effects the importance of identifying such deformations is not only related to the hazard they can pose but also to the understanding of changes that permafrost or local hydrological conditions undergo here we carry out a multi temporal insar analysis over a mountainous area 8000 km2 large straddling north western bhutan and southern tibet we propose a methodology to separate locally deforming areas from the effects of long wavelength signals through the analysis of the spatio temporal behaviour of 4 years long time series of surface displacements we present the mapping of hundreds of small scale features that appear to be actively deforming as well as several examples of reversible deformation rarely detected at this scale in such a challenging and vast region the analysis of the multi annual trend of ground deformation shows a relatively small number of irreversible gravitational movements clearly related to rock slides which attests a low level of recent activity of large rock slope instabilities in the region in the southernmost lower elevation parts of the study area we quantify reversible surface displacements with amplitudes ranging between 5 and 17 mm and showing maximum displacements towards the satellite in summer months thus compatible with hydro mechanical effects related to groundwater table variations in addition the ground movement induced by the active layer s response to thawing and freezing over the gentler slopes and high elevation permafrost regions of bhutan and southern tibet is on average around 10 mm with maxima up to 28 mm the localised displacements appear to be largely associated to braided stream plains glacier outwash plains or low angle fine sediment covered slopes

lower crustal relaxation beneath the tibetan plateau and qaidam basin following the 2001 kokoxili earthquake summary in 2001 november a magnitude 7 8 earthquake ruptured a 400 km long portion of the kunlun fault northeastern tibet in this study we analyse over five years of post seismic geodetic data and interpret the observed surface deformation in terms of stress relaxation in the thick tibetan lower crust we model gps time series first year and insar line of sight measurements years two to five and infer that the most likely mechanism of post seismic stress relaxation is time dependent distributed creep of viscoelastic material in the lower crust since a single relaxation time is not sufficient to model the observed deformation viscous flow is modelled by a lower crustal burgers rheology which has two material relaxation times the optimum model has a transient viscosity 9 1017 pa s steady state viscosity 1 1019 pa s and a ratio of long term to maxwell shear modulus of 2 3 this model gives a good fit to gps stations south of the kunlun fault while displacements at stations north of the fault are over predicted we attribute this asymmetry in the gps residual to lateral heterogeneity in rheological structure across the southern margin of the qaidam basin with thinner crust higher viscosities beneath the basin than beneath the tibetan plateau deep afterslip localized in a shear zone beneath the fault rupture gives a reasonable match to the observed insar data but the slip model does not fit the earlier gps data well we conclude that while some localized afterslip likely occurred during the early post seismic phase the bulk of the observed deformation signal is due to viscous flow in the lower crust to investigate regional variability in rheological structure we also analyse post seismic displacements following the 1997 manyi earthquake that occurred 250 km west of the kokoxili rupture we find that viscoelastic properties are the same as for the kokoxili area except for the transient viscosity which is 5 1017 pa s the viscosities estimated for the manyi and kokoxili areas are consistent with constraints obtained from other earthquakes in the northwest and south central parts of the tibetan plateau

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

characterization of open and closed volcanic systems in indonesia and mexico using insar time series 1 we use 2007 2011 advanced land observing satellite alos data to perform an arc wide interferometric synthetic aperture radar insar time series survey of the trans mexican volcanic belt tmvb and to study time dependent ground deformation of four indonesian volcanoes selected following the 2007 2009 study of chaussard and amelung 2012 our objectives are to examine whether arc volcanoes exhibit long term edifice wide cyclic deformation patterns that can be used to characterize open and closed volcanic systems and to better constrain in which cases precursory inflation is expected we reveal deformation cycles at both regularly active and previously inactive indonesian volcanoes but we do not detect deformation in the tmvb reflecting a lower activity level we identify three types of relationships between deformation and activity inflation prior to eruption and associated with or followed by deflation kerinci and sinabung inflation without eruption and followed by slow deflation agung and eruption without precursory deformation merapi colima and popocatepetl at merapi no significant deformation is detected even during eruption the first two cases correspond to closed volcanic systems and suggest that the traditional model of magmatic systems and eruptive cycles do apply to andesitic volcanoes i e inflation and deflation episodes associated with magma accumulation or volatile exsolution in a crustal reservoir followed by eruptions or in situ cooling in contrast the last case corresponds to open volcanic systems where no significant pressurization of the magmatic reservoirs is taking place prior to eruptions and thus no long term edifice wide ground deformation can be detected we discuss these results in terms of insar s potential for forecasting volcanic unrest

large scale insar monitoring of permafrost freeze thaw cycles on the tibetan plateau multitemporal interferometric synthetic aperture radar insar observations are used to characterize spatial variations of the permafrost active layer and its temporal evolution in northwestern tibet we develop a method to enhance insar performances for such difficult terrain conditions and construct an 8 year timeline of the surface deformation over a 60 000 km2 area the ground movement induced by the active layer s response to climate forcing is limited to cenozoic sedimentary basins and is spatially variable in both its seasonal amplitude 2 5 12 mm and multiannual trend 2 to 3 mm yr a degree day integrated model adjusted to the data indicates that subsidence occurs when the surface temperature exceeds zero may to october over areas where seasonal movements are large 8 mm the period of subsidence is delayed by 1 2 months over areas where smaller seasonal movements are observed suggesting an unsaturated soil where water occurs in the deeper part of the active layer

resolving mantle and crustal contributions to ancient hydrothermal fluids hear isotopes in fluid inclusions from dae hwa wmo mineralisation south korea abstract helium and argon isotopes from fluid inclusions in individual colour zones b c d and e of a large scheelite crystal from the 88 ma dae hwa w mo deposit south korea trace the source and history of the ore fluids a gradual decrease of the fluid 3 he 4 he 3 he 36 ar and 40 ar 36 ar from the core to the edge of the scheelite reflects the progressive dilution of a magmatic fluid by meteoric water and is consistent with the previously observed decrease of 18oh2o and fluid inclusion homogenisation temperatures th shelton et al 1987 the covariation of fluid inclusion he ar isotope systematics with 18o and th defines a magmatic component with 3 he 4 he 1 2 10 6 3 he 36 ar 0 01 and 40 ar 36 ar 1000 anomalously high helium and argon isotope ratios in zone d fluids represents undiluted magmatic noble gases this may reflect local variation in the magmatic gas flux or gas loss due to boiling of the hydrothermal fluids prior to mixing with magmatic gas helium and argon isotope systematics constrain mantle and crustal components in the hydrothermal fluids 40 ar 3 he 4 5 104 are close to the mid ocean ridge basalt value implying that 40ar is mantle in origin radiogenic isotope ratios of the mantle endmember 40 ar 4 he 0 69 0 06 are similar to contemporary geothermal fluids the coincidence of mantle derived he and ar in the fluids is strong evidence that mantle melting during late cretaceous subduction triggered the crystal melting responsible for granite formation 40 ar 4 he of the meteoric fluid 0 007 0 001 is far lower than the crystal production ratio 0 2 implying an origin in crust below 200 c

accounting for atmospheric delays in insar data in a search for long wavelength deformation in south america insar has been successfully used to observe the deformation of the earth s surface from many processes but mostly dealing with relatively large signals 1 cm over short wavelengths 100 km we use interferometric synthetic aperture radar insar data from two orbital tracks in northern chile to study the feasibility of imaging the broad interseismic ground deformation signal from the nazca plate subduction in order to measure 1 5 cm year of ground motion across 1000 km of satellite track length due to interseismic loading of the subduction interface the atmospheric contribution cannot be ignored we attempt to remove the atmospheric signal using global weather models and by estimating atmospheric parameters directly from the insar data due to the poor temporal and spatial resolutions of the weather model this method fails to produce reliable results the empirical model reduces the phase variance in the interferograms but leaves a residual signal that continues to mask the interseismic signal which demonstrates the importance of carefully applying corrections to the data as they can significantly affect any interpretation that is based on the corrected observations although the methods presented here are not suited for removing all atmospheric path delays this paper does provide suggestions about improvements that can be made to corrective techniques methods that should be further developed are the following 1 corrections with independent and direct observations of atmospheric properties e g continuous gps or satellite observations e g the meris sensor 2 improvements using empirical corrections either in conjunction with a deformation model or constrained by real atmospheric structures and 3 further work with high resolution and improved weather models

imaging geodesy toward centimeter level ranging accuracy with terrasar x in this paper we report on experiments to measure large scale earth surface displacements such as those caused by solid earth tides with centimeter level accuracy using terrasar x radar images with two totally different approaches corner reflectors and image correlation techniques we show the clear interrelation between the radar range measurements and the projection of the solid earth tide motion vector onto the radar line of sight pixel location accuracies of up to 2 6 cm standard deviation can be achieved after a single calibration we further demonstrate that solid earth tides and tropospheric water vapor variations are the largest sources of ranging error if not compensated for alternatively tropospheric water vapor can be estimated with centimeter accuracy using our proposed technique of synthetic aperture radar sar image correlation and solid earth motion compensation by the existing models we also consider ionospheric delays which improve the results marginally in the x band our results show the best ranging accuracies so far reported for spaceborne radar amplitude images and make terrasar x together with our simple compensation methodology suitable for the imaging of centimeter level earth displacements absolute measurements of volcanoes or glaciers are possible without the use of ground equipment and without the use of sar interferometry thus avoiding the associated problems of phase ambiguity phase unwrapping and reference points

constraining ice mass loss from jakobshavn isbrae greenland using insar measured crustal uplift summary jakobshavn isbrae in west greenland has been undergoing dramatic thinning since 1997 applying the interferometric synthetic aperture radar insar technique to radarsat 1 sar data we measure crustal uplift near jakobshavn isbrae caused by recent ice mass loss the crustal uplift is predominantly at long spatial wavelengths larger than 10 km and thus is difficult to separate from insar orbit errors we reduce the effects of orbit errors by removing long wavelength deformation signals using conventional insar baseline fitting methods we find good agreement between the remaining short scale insar estimated deformation rates during 2004 2008 and the corresponding short scale components of a deformation model that is based on changes in ice elevation measured by nasa s airborne topographic mapper atm we are also able to use the insar measured deformation to invert for the spatial pattern of ice thinning overall our results suggest that despite the inherent difficulties of working with a signal that has significant large scale components insar measured crustal deformation can be used to study the ice mass loss of a rapidly thinning glacier and its surrounding catchment providing both a constraint on any existing model of ice mass loss and a data source that can be used to invert for ice mass loss these new applications of insar can help to better understand a glacier s rapid response to a warming climate

satellite geodetic imaging reveals internal deformation of western tibet 1 it is often assumed that the majority of the interseismic strain accumulates around the major mapped geological block boundaries however numerous recent earthquakes in the continents have occurred on faults that were previously unidentified existing deformation data from tibet are insufficiently dense to map the distribution of interseismic strain here we combine 265 interferograms formed from 166 radar images with gps data to constrain a high resolution velocity field covering 200 000 km2 of western tibet we confirm that the slip rate of the karakoram fault is low 6 mm yr but show that areas of focused strain do not coincide with the major fault structures some of this strain is due to postseismic relaxation after a mw 6 8 earthquake that occurred in 1996 on a structure that is difficult to identify in satellite imagery models of seismic hazard that rely on imperfect knowledge of the boundaries of crustal blocks can therefore underestimate hazard from unknown faults

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