sinking cities in indonesia alos palsar detects rapid subsidence due to groundwater and gas extraction abstract we use interferometric synthetic aperture radar insar time series analysis of alos l band sar data to resolve land subsidence in western indonesia with high spatial and temporal resolution the data reveal significant subsidence in nine areas including six major cities at rates up to 22 cm year land subsidence is detected near lhokseumawe in medan jakarta bandung blanakan pekalongan bungbulang semarang and in the sidoarjo regency the fastest subsidence occurs in highly populated coastal areas particularly vulnerable to flooding we correlate the observed subsidence with surface geology and land use despite the fact that subsidence is taking place in compressible deposits there is no clear correlation between subsidence and surface geology in urban areas we find a correlation between rapid patchy subsidence and industrial land use and elsewhere with agricultural land use this suggests that the subsidence is primarily caused by ground water extraction for industrial and agricultural use respectively we also observe subsidence associated with exploitation of gas fields near lhokseumawe and in the sidoarjo regency a continuation of these high rates of subsidence is likely to put much of the densely populated coastal areas below relative sea level within a few decades

copper mobility in the eastern creek volcanics mount isa australia evidence from laser ablation icp ms of iron titanium oxides the palaeoproterozoic eastern creek volcanics are a series of copper rich tholeiitic basalts which occur adjacent to the giant sediment hosted mount isa copper deposit in queensland australia the volcanic rocks are often cited as the source of metals for the deposit new laser ablation icp ms analyses of iron titanium oxides from the basalts provide evidence for the local mobilisation of copper during regional greenschist facies metamorphism this interpretation is based on the observation that copper bearing magmatic titanomagnetite was destabilised during greenschist facies metamorphism and the new magnetite which crystallised was copper poor petrological observations regional geochemical signatures and geochemical modelling suggest that the mobilised copper was concentrated in syn metamorphic epidote rich alteration zones creating a pre concentration of copper before the main mineralisation event at mount isa geochemical modelling demonstrates this process is enhanced by the addition of co2 from adjacent carbonate rich sediments during metamorphic devolatilisation regional geochemical data illustrate elevated copper concentrations in epidote rich zones high cao but where these zones are overprinted by potassic alteration high k2o copper is depleted a two stage model is proposed whereby after metamorphic copper enrichment in epidote titanite alteration zones an oxidised potassium rich fluid leached copper from the epidote altered metabasalts and deposited it in the overlying sedimentary rocks to form the mount isa copper deposit this ore forming fluid is expressed regionally as potassium feldspar rich veins and locally as biotite rich alteration which formed around major fluid conduits between the metabasalt metal source rocks and the overlying deposit host sequence this model is consistent with the remobilisation of copper from mafic source rocks as has been found at other world class copper deposits

evidence of the present relative land stability of venice italy from land sea and space observations 1 the city of venice is very vulnerable to loss in surface elevation as a result of subsidence and eustacy because of its small elevation above sea level the alarm of the scientific community related to this persistent problem is increasing because of the forecasts of sea level rise caused by global warming in order to evaluate the present relative subsidence of venice a study has been performed by combining high precision leveling satellite radar interferometry sri and tide gauge measurements the analysis of the most recent data points out with an unprecedented detail the present ground stability of the city

pace of landscape evolution in the sierra nevada california revealed by cosmogenic dating of cave sediments we report 26 al 10 be based ages of sierra nevada caves that constrain detailed late pliocene and quaternary river incision his tories for five river canyons rapid incision of 0 2 mm yr from 2 7 to ca 1 5 ma slowed markedly to 0 03 mm yr thereafter likely reflecting the combined effects of a transient erosional re sponse to pliocene rock uplift and periodic mantling of riverbeds with glacially derived sediment in the late quaternary while 400 m of incision has occurred in the past 2 7 m y outpacing interfluve erosion and thereby increasing the local relief canyons as deep as 1 6 km existed prior to that time these new erosion rates strength en the case for tectonically driven late cenozoic uplift

geomorphically driven late cenozoic rock uplift in the sierra nevada california geologists have long accepted that the sierra nevada california experienced significant late cenozoic tectonically induced uplift a flexural isostatic model presented here shows however that a large fraction of the primary evidence for uplift could be generated by the lithospheric response to coupled erosion of the sierra nevada and deposition in the adjacent central valley and therefore requires less tectonic forcing than previously believed the sum of range wide erosion and the resultant isostatic rock uplift would have lowered sierra mean elevation by 200 to 1000 meters since 10 million years ago and could also have increased summit elevations during the current period of relief production

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

the microfossils from the proterozoic urquhart shale mount isa queensland and their significance in relation to the depositional environment diagenesis and mineralisation the urquhart shale from mount isa queensland hosts major lead zinc and copper orebodies re examination of organic matter from the lead zinc ore bodies has shown that abundant microfossils characteristic of lacustrine environments are present and substantiates earlier results of love and zimmerman 1961 the framboid residues described by these authors are not microfossils but nevertheless the occurrence of framboidal pyrite has important implications for the timing of lead zinc mineralisation a diagenetic model is proposed for the lead zinc ore bodies and a later transgressive event accounts for the mode of occurrence of the copper ore bodies

separating natural and anthropogenic vertical movements in fast subsiding areas the po plain n italy case the geological and the anthropogenic components of vertical movement act on different time scales millions to thousands years and hundreds to tens of years respectively this peculiarity has been used in order to separate the factors controlling sea level changes in the po plain area the component due to long term geological processes is calculated from stratigraphic data commercial wells and seismic lines adding to this long term component the contribution of pleistocene deglaciation obtained from analytical models an estimate of the total natural component of vertical velocities is obtained the validity of these values is confirmed by comparison with velocities obtained from archaeological data and detailed palynological and paleontological analyses the anthropogenic components can be inferred by comparison between the total natural vertical velocities we calculate and vertical velocities obtained from other data sets two applications are proposed using tide gauge records and geodetic data respectively

block kinematics of the pacific north america plate boundary in the southwestern united states from inversion of gps seismological and geologic data 1 the active deformation of the southwestern united states 30 41 n is represented by a finite number of rotating elastic plastic spherical caps gps derived horizontal velocities geologic fault slip rates transform fault azimuths and earthquake derived fault slip vector azimuths are inverted for block angular velocities creep on block bounding faults permanent strain rates within the blocks and the rotations of 11 published gps velocity fields into to a common north american reference frame gps velocities are considered to be a combination of rigid block rotations recoverable elastic strain rates resulting from friction on block bounding faults and nonrecoverable strain rates resulting from slip on faults within the blocks the resulting pacific north america angular velocity is similar to some published estimates and satisfies transform azimuths and one spreading rate in the gulf of california earthquake slip vectors in the gulf of california and alaska and gps velocities along coastal california and within the pacific basin published fault slip rates are satisfied except in the southern mojave desert where the motion of the mohave block relative to north america is faster than can be explained by mapped faults the largest blocks the sierra nevada great valley and the eastern basin and range show permanent strain rates after removing elastic strain of only a few nanostrain per year demonstrating approximately rigid behavior observed horizontal strain rates correlate strongly with predicted strain rates from known faults suggesting that the short term strains evident in gps velocities are largely elastic in only about 20 of the region is distributed deformation needed to match the data indicating that a plate tectonic style description of the deformation of the western united states is plausible most blocks rotate about vertical axes at approximately the same rate as the pacific relative to north america suggesting that locally spin rates are communicated from block to block arguing against both floating block and ball bearing mechanisms of block rotation the similarities of the blocks spin rates to that of the pacific suggests that the pacific strongly influences their motions through edge tractions however it is shown that the blocks cannot rotate about the pacific north america pole without spinning counter to the sense of pacific north america shear unlike some other broad plate boundaries in the western united states vertical axis rotations take up very little of the slip rate budget across the region

anthropogenic and geologic influences on subsidence in the vicinity of new orleans louisiana new measurements of ongoing subsidence of land proximal to the city of new orleans louisiana and including areas around the communities of norco and lutcher upriver along the mississippi are reported the rates of vertical motion are derived from interferometric synthetic aperture radar insar applied to uninhabited aerial vehicle synthetic aperture radar uavsar data acquired on 16 june 2009 and 2 july 2012 the subsidence trends are similar to those reported for 2002 2004 in parts of new orleans where observations overlap in particular in michoud the 9th ward and chalmette but are measured at much higher spatial resolution 6 m the spatial associations of cumulative surface movements suggest that the most likely drivers of subsidence are groundwater withdrawal and surficial drainage dewatering activities high subsidence rates are observed localized around some major industrial facilities and can affect nearby flood control infrastructure substantial subsidence is observed to occur rapidly from shallow compaction in highly localized areas which is why it could be missed in subsidence surveys relying on point measurements at limited locations

hydrogen isotopes in eocene river gravels and paleoelevation of the sierra nevada we determine paleoelevation of the sierra nevada california by tracking the effect of topography on precipitation as recorded in hydrogen isotopes of kaolinite exposed in gold bearing river deposits from the eocene yuba river the data compared with the modern isotopic composition of precipitation show that about 40 to 50 million years ago the sierra nevada stood tall 2200 meters a result in conflict with proposed young surface uplift by tectonic and climatic forcing but consistent with the sierra nevada representing the edge of a pre eocene continental plateau

increasing long wavelength relief across the southeastern flank of the sierra nevada california abstract a high degree of correlation between present day relative rock uplift measured using continuous gps geodesy and spatially averaged surface elevations suggests that long wavelength topographic relief is presently increasing along the southeastern flank of the sierra nevada range and within an adjacent portion of the northern basin and range province current estimates for erosion rate are an order of magnitude smaller than the relative rates determined by geodesy thus although the uplift serves to enhance long wavelength relief it cannot be explained entirely as an isostatic response to erosion if uplift rates have been constant through time the duration over which the uplift could have been active

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

transient deformation in california from two decades of gps displacements implications for a three dimensional kinematic reference frame our understanding of plate boundary deformation has been enhanced by transient signals observed against the backdrop of time independent secular motions we make use of a new analysis of displacement time series from about 1 000 continuous global positioning system gps stations in california from 1999 to 2018 to distinguish tectonic and nontectonic transients from secular motion a primary objective is to define a high resolution three dimensional reference frame datum for california that can be rapidly maintained with geodetic data to accommodate both secular and time dependent motions to this end we compare the displacements to those predicted by a horizontal secular fault slip model for the region and construct displacement and strain rate fields over the past 19 years california has experienced 19 geodetically detectable earthquakes and widespread postseismic deformation we observe postseismic strain rate variations as large as 1 000 nstrain year with moment releases equivalent up to an mw6 8 earthquake we find significant secular differences up to 10 mm year with the fault slip model from the mendocino triple junction to the southern cascadia subduction zone the northern basin and range and the santa barbara channel secular vertical uplift is observed across the transverse ranges coastal ranges sierra nevada as well as large scale postseismic uplift after the 1999 mw7 1 hector mine and 2010 mw7 2 el mayor cucapah earthquakes we also identify areas of vertical land motions due to anthropogenic natural and magmatic processes finally we demonstrate the utility of the kinematic datum by improving the accuracy of high spatial resolution 12 day repeat cycle sentinel 1 interferometric synthetic aperture radar displacement and velocity maps

the uplift of the sierra nevada and implications for late cenozoic epeirogeny in the western cordillera tilted cenozoic strata in the eastern great valley california record progressive late cenozoic uplift of the sierra nevada the magnitude of tilting is combined with other geologic data using a technique pioneered by grant and others to infer the rate and timing of post late miocene uplift between the kings river and the feather river angular unconformities of late neogene age have been reported throughout the east central great valley typically stratigraphic units of late oligocene through miocene pliocene age beneath the unconformities dip approximately 1 2 1 6 southwest middle to late pliocene units above the unconformities dip approximately 0 6 0 9 southwest and progressively overlap younger units from east to west these angular unconformities are interpreted to represent the onset of late cenozoic uplift of the sierra nevada due to westward tilting dated volcaniclastic units in the east central sacramento valley bracket the onset of tilting there between 3 4 and 8 4 ma stratigraphic and geologic relations from the stanislaus river area eastern san joa quin valley suggest that the late cenozoic tilting probably began approximately 5 ma previously published tilt data from the san joaquin valley combined with new work in the eastern sacramento valley indicate that the rate of post late miocene tilting has been approximately uniform in the east central great valley early to middle pleistocene units typically dip 0 5 0 7 southwest middle pleistocene units dip 0 2 0 4 middle to late pleistocene units dip 0 1 0 15 late pleistocene units dip 0 05 0 1 if it is assumed that major westward tilting began 5 ma these data indicate an approximately uniform tilting rate of 0 28 per million years these data have important implications for models of the uplift simultaneous inception of tilting in the east central great valley at approximately 5 ma does not support models that link uplift of the sierra nevada to the migration of the mendocino triple junction late cenozoic tilting of the sierra nevada block does not appear to coincide temporally with the onset of major basin and range extension the uplift may be due to thinning of the mantle lithosphere beneath the sierra nevada but the tilt data do not afford a direct test of this hypothesis post late miocene tilting of the sierra nevada is temporally associated with late cenozoic uplift of the northern basin and range uplift of the cascades uplift of the colorado plateau and uplift of the southern rocky mountains supporting the contention that tilting of the sierra nevada may have occurred as part of a cordillera wide uplift event

comment on recent subsidence of the venice lagoon from continuous gps and interferometric synthetic aperture radar by y bock s wdowinski a ferretti f novali and a fumagalli

the seismically active atalanti fault in central greece a steeply dipping fault zone imaged from magnetotelluric data abstract the wnw ese striking atalanti fault is one of the large fault segments of the ca 110 km long wnw ese trending sperchios chalkis fault system that subsided along the ne slopes of the kalidromon and chlomo mts in central greece forming an extensive graben similar to the corinthiakos gulf although the fault is characterized by recent seismic activity it has up to now not been investigated by means of geophysical methods that could define the geometrical features of the structure in depth magnetotelluric measurements performed along three 14 km long profiles a b and c and across the fault with a total of 28 stations indicate that its geoelectric strike is wnw ese two dimensional bimodal and the determinant of the impedance tensor inversions were applied to the data the best data fit was achieved using the determinant data the resulting 2d models were further interpreted both separately and all together in order to define the geometry of the structure down to a depth of several kilometers the derived resistivity model defines that the atalanti fault strikes wnw ese and forms a damage zone that contains two high angle fault branches that dip at angles of 60 and 80 respectively thus the interpreted geometry of the atalanti fault and consequently the sperchios chalkis fault system differs from previous interpretation of a low angle extensional crustal structure in addition the electrical resistivity model indicates the subsidence of the overthrust of the internal hellenides over the parnassos zone toward the nne from a depth of 2 km to deeper crustal levels due to the atalanti fault

evolutionary aspects of lithosphere discontinuity structure in the western u s 1 we have produced common conversion point ccp stacked ps and sp receiver function image volumes of the moho and lithosphere asthenosphere boundary lab beneath the western united states using transportable array data the large image volumes and the diversity of tectonic environments they encompass allow us to investigate evolution of these structural discontinuities the moho is a nearly continuous topographic surface whereas the lab is not and the seismic images show a more complex expression the first order change in lab depth in the western u s occurs along the cordilleran hingeline the former laurasian passive margin along the southwestern precambrian north american terranes the lab is about 50 deeper to the east of the hingeline than to the west with most of the increase in lab thickness being in the mantle lithosphere we infer that the moho and the lab are late mesozoic or cenozoic everywhere west of the hingeline modified during farallon subduction and its aftermath between the hingeline and the rocky mountain front the lab and to a lesser extent the moho have been partially reset during the cenozoic by processes that continue today seismicity and recent volcanism in the interior of the western u s are concentrated along gradients in crustal and or lithospheric thickness for example the hingeline and the eastern edge of the coastal volcanic magmatic terranes to us this suggests that lateral gradients in integrated lithospheric strength focus deformation similarly areas conjectured to be the sites of convective downwellings and associated volcanism are located along gradients in regional lithosphere thickness

rhenium osmium systematics of the mount isa copper orebody and the eastern creek volcanics queensland australia implications for ore genesis the syn tectonic breccia hosted mount isa cu deposit in northwest queensland is the largest sediment hosted cu deposit in australia whole rock samples of chalcopyrite rich cu ore form an isochron with a re os age of 1 372 41 ma this age is more than 100 ma younger than the previously accepted age of cu ore formation an ar ar mineral age for biotite separated from the host rocks within the alteration envelope to the cu orebody this discrepancy cannot be unequivocally resolved due to a lack of other absolute geochronological constraints for cu mineralisation or the deformation event associated with cu emplacement the 1 372 41 ma date may reflect a the time of cu deposition b the time of a hydrothermal event that reset the re os signature of the cu ore or c mixing of the re os isotope systematics between the host rocks and cu bearing fluids however a range of published ar ar and rb sr dates for potassic alteration associated with cu mineralisation also records an event between 1 350 and 1 400 ma and these are consistent with the 1 372 ma re os age the 1 8 ga eastern creek volcanics are a series of tholeiitic basalts with a primary magmatic cu enrichment which occur adjacent to the mount isa cu deposit the whole rock os isotopic signature of the eastern creek volcanics ranges from mantle like values for the upper pickwick member to more radiogenic crustal values for the lower cromwell member the re os isotope signature of the cu ores overlaps with those calculated for the two volcanic members at 1 372 ma hence the os isotope data are supportive of the concept that the os in the cu ores was sourced from the eastern creek volcanics by inference it is therefore postulated that the eastern creek volcanics are the source of cu in the mount isa deposit as both os and cu are readily transported by oxidised hydrothermal fluids such as those that are thought to have formed the cu orebody the pickwick member yields a re os isochron age of 1 833 51 ma which is within error of previously reported age constraints the initial 187os 188os isotopic ratio of 0 114 0 067 os 0 7 is slightly subchondritic and together with other trace element geochemical constraints is consistent with a subcontinental lithospheric mantle source the pickwick member records a minimum age of ca 1 95 ga for melt depletion in the subcontinental lithospheric mantle beneath the mount isa inlier prior to the extraction of the magmas which formed the eastern creek volcanics this corresponds with the end of subduction related magmatism along the eastern margin of the northern australian craton which included the mount isa inlier

apennines subduction related subsidence of venice italy 1 the foreland regional monocline related to the northern apennines subduction can be followed from the po basin to the friuli region italy at least 240 km north eastward in seismic reflection profiles of the po basin and of the northern adriatic sea the dip of the regional monocline gradually decreases from about 22 to close to 0 pleistocene sediments onlap and pinchout to the northeast venice is located on a segment of the active monocline dipping about 1 8 to the southwest in sediments around the venice area the 1 43 ma limit is in the 960 1500 m depth range indicating a long term subsidence rate of about 0 7 1 0 mm yr therefore a significant part of the natural component of the town subsidence is related to the north eastward retreat of the adriatic subduction the subduction related downflexure affects the whole of the po plain basin and part of the southern alps where it opposes to the general uplift related to orogenesis

inflation rate of the colli albani volcanic complex retrieved by the permanent scatterers sar interferometry technique 1 we analyzed 99 ers sar images of the colli albani volcano using the permanent scatterers technique we retrieved the average surface displacement velocities for over 100 000 scatterers for the period 1993 2000 showing that present deformation is concentrated in the area of most recent volcanic activity with rates up to 2 6 mm yr in the satellite line of sight we inverted the observed deformation using several analytical solutions for volcanic sources in an elastic half space the best fit is obtained with two mogi sources aligned in a n s direction at 5 and 7 km depth beneath the western flank of the volcano

dating topography of the sierra nevada california using apatite u th he ages the upward motion of rock masses relative to the earth s surface has been documented for most of the main mountain belts using thermochronological and petrological techniques more fundamental to the physical processes of mountain building however is the motion of the earth s surface itself which remains elusive here we describe a technique for estimating the age of topographic relief by mapping the low temperature thermal structure imparted by river incision using the ages of apatites determined from their uranium thorium and helium contents the technique exploits horizontal variations in temperature in the shallow crust that result from range normal river drainages because cooling beneath ancient river valleys occurs earlier than beneath intervening ridges our results from the sierra nevada california indicate that two of the modern transverse drainages the kings and the san joaquin had developed deep canyons by the late cretaceous period suggesting that the high topography of the range is 50 60 million years older than generally thought

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

on the use of quasi static deformation to understand reservoir fluid flow deformation above a producing reservoir provides a valuable source of information concerning fluid flow and flow properties quasi static deformation occurs when the displacements are so slow that we may neglect inertial terms in the equations of motion we present a method for inferring reservoir volume change and flow properties such as permeability from observations of quasi static deformation such displacements may represent surface deformation such as tilt leveling interferometric synthetic aperture radar insar or bathymetry observations or subsurface deformation as inferred from time lapse seismic surveys in our approach the equation for fluid flow in a deforming reservoir provides a mapping from estimated fractional volume changes to reservoir permeability variations if the reservoir behaves poroelastically over the interval of interest all the steps in this approach are linear thus the inference of reservoir permeability from deformation data becomes a linear inverse problem in an application to the wilmington oil field in california we find that observed surface displacements obtained by leveling and insar are indeed compatible with measured reservoir volume fluxes we find that the permeability variations in certain layers coincide with fault block boundaries suggesting that in some cases faults are controlling fluid flow at depth

quantitative evidence that compaction of holocene sediments drives the present land subsidence of the po delta italy 1 deltas are highly dynamic coastal systems that over the last few decades have generally experienced a substantial area loss caused by trapping of river sediments in upland drainage basins as well as land subsidence due to natural and anthropogenic causes a major example is the po delta in the mediterranean in northeastern italy this area has experienced as much as 3 m of land subsidence from the 1930s to the 1970s primarily because of the extraction of gas bearing waters however present subsidence rates are largely unknown and the ground settlement is supposedly controlled by natural long term deep processes we have combined radar interferometric point target analysis ipta with previous geomorphological investigations on aerial satellite images and seismic surveys and geochronological data from core samples and geomechanical in situ tests to assess the current sinking of the delta and to understand the processes controlling the vertical movement the high density of the measurable point targets more than 15 000 allows characterization of the spatial variation in the vertical land motions vlm ranging from 1 to 15 mm yr we find that subsidence rates are significantly correlated with the age of highly compressible holocene deposits that compose the shallowest 30 40 m of the sedimentary sequence a typical log type consolidation equation applicable at the scale of the entire delta has been obtained we conclude that the consolidation of late holocene sediments is the major cause of the present land subsidence in the po river delta this finding has significant impact on the understanding of many other modern deltas that were formed in the lower holocene epoch

erosional equilibrium and disequilibrium in the sierra nevada inferred from cosmogenic 26al and 10be in alluvial sediment we used cosmogenic 26 al and 10 be in stream sediment to measure landscape scale erosion rates for topographically diverse catchments at seven sierra nevada sites at three sites erosion rates and hillslope gradients are strongly correlated increasing with proximity to fault scarps and river canyons which appear to have accelerated local base level lowering rates and thus increased catchment erosion rates by up to 15 fold at four other sites far from fault scarps and river canyons erosion rates are much more uniform and less sensitive to average hillslope gradient our measurements show that contrasts in landscape erosion rates cannot be inferred from hillslope gradients alone because landscapes can evolve toward a state of erosional equilibrium in which steep and gentle slopes erode at similar rates

insar based detection method for mapping and monitoring slow moving landslides in remote regions with steep and mountainous terrain an application to nepal abstract mapping and monitoring landslides in remote areas with steep and mountainous terrain is logistically challenging expensive and time consuming yet in order to mitigate hazards and prevent loss of life in these areas and to better understand landslide processes high resolution measurements of landslide activity are necessary satellite based synthetic aperture radar interferometry insar provides millimeter scale measurements of ground surface deformation that can be used to identify and monitor landslides in remote areas where ground based monitoring techniques are not feasible here we present a novel insar deformation detection approach which uses double difference time series with local and regional spatial filters and pixel clustering methods to identify and monitor slow moving landslides without making a priori assumptions of the location of landslides we apply our analysis to freely available copernicus sentinel 1 satellite data acquired between 2014 and 2017 centered on the trishuli river drainage basin in nepal we found a minimum of 6 slow moving landslides that all occur within the ranimatta lithologic formation phyllites metasandstones metabasics these landslides have areas ranging from 0 39 to 1 66 km2 and long term dry season displacement rates ranging from 2 1 to 8 8 cm yr due to periods of low coherence during the monsoon season june september each year and following the 25 april 2015 mw7 8 gorkha earthquake our time series analysis is limited to the 2014 2015 and 2016 2017 dry seasons september may we found that each of the landslides displayed slightly higher rates during the 2014 period likely as a result of higher cumulative rainfall that fell during the 2014 monsoon season although we do not have high quality insar data to show the landslide evolution directly following the gorkha earthquake the similar rates of movement before 2014 2015 and after 2016 2017 gorkha suggest the earthquake had negligible long term impact on these landslides our findings highlight the potential for region wide mapping of slow moving landslides using freely available remote sensing data in remote areas such as nepal and future work will benefit from expanding our methodology to other regions around the world

disruptive influences of residual noise network configuration and data gaps on insar derived land motion rates using the sbas technique abstract the interferometric synthetic aperture radar insar small baseline subset sbas technique can be applied to land with varying deformation magnitudes ranging from mm yr to tens of cm yr sbas defines a network of interferograms that is limited by temporal and spatial baseline thresholds that are often applied arbitrarily or in apparently subjective ways in the literature we use simulated sar data to assess 1 the influence of residual noise and sbas network configuration on insar derived deformation rates and 2 how the number of interferograms and data gaps in the time series may further impact the estimated rates this leads us to an approach for defining a sbas network based on geodetic reliability theory represented by the redundancy number r number simulated insar datasets are generated with three subsidence signals of linear rates plus sinusoidal annual amplitudes of 2 mm yr plus 2 mm 20 mm yr plus 5 mm and 100 mm yr plus 10 mm contaminated by gaussian residual noise bounded within 2 2 mm 5 5 mm and 10 10 mm corresponding to standard deviations of approximately 0 5 mm 1 5 mm and 3 0 mm respectively the influence of data gaps is investigated through simulations with percentages of missing data ranging from 5 to 50 that are selected 1 randomly across the 4 year time series and 2 for three month windows to represent the northern winter season where snow cover may cause decorrelation these simulations show that small deformation rates are most adversely affected by residual noise in some extreme cases the recovered trends can be contrary to the signal i e indicating uplift when there is simulated subsidence we demonstrate through simulations that the r number can be used to pre determine the reliability of sbas network design indicating the r values between 0 8 and 0 9 are optimal r numbers less than 0 3 can deliver erroneous rates in the presence of noise commensurate with the magnitude of deformation finally the influence of data gaps is not as significant compared to other factors such as a change in the number of interferograms used although the blocks of winter gaps in the sbas network show a larger effect on the rates than gaps at random intervals across the simulated time series

isostatic rebound active faulting and potential geomorphic effects in the lake lahontan basin nevada and california the high shoreline of the late pleistocene sehoo lake in the lahontan basin is used as a passive strain marker to delineate the magnitude and character of regional deformation since 13 ka the elevations of 170 high shoreline sites document that the once horizontal equipotential shoreline which traverses almost 4 of latitude and 3 of longitude is now deflected vertically about 22 m most of the deformation is attributed to isostatic rebound but a small down to the north regional tilting also appears to contribute to the overall deformation pattern active faults locally offset the high shoreline but cannot explain the regional upwarping attributed to isostatic rebound since 13 ka preliminary models of the rebound yield an upper mantle viscosity of 10 18 pa s that implies a maxwell relaxation time of about 300 yr the rapid earth response coupled with the rapid fall in lake level at the end of pleistocene time may have acted to divert some of the major rivers flowing into the basin from one terminal subbasin to another the regional deformation caused by the rebound may also have acted to control the present location of honey lake these shoreline data therefore support the potential for a link be

recent discoveries of proterozoic microfossils in south central brazil abstract twenty two precambrian microfossiliferous localities seven newly reported here are known from the sao francisco block and associated brasilia fold belt of south central brazil reported from outcrop and drill core samples of mesoand neoproterozoic cherts carbonates and siliciclastics of the 1170 to 950 ma old paranoa group and the 950 to 700 ma old sao francisco supergroup composed of the jequitai formation and the overlying bambui group representatives of nearly 30 genera of proterozoic microfossils chiefly cyanobacteria and subsidiary acritarchs have been reported from these strata preserved mostly within carbonaceous black chert in flat laminated and high relief stromatolites and represent a wide spectrum of environments evidently ranging from nearshore lagoonal to supratidal intertidal subtidal and offshore marine settings contrary to previously held views the microfossils are generally more abundant and better preserved in the older unit paranoa group than in the younger one sao francisco supergroup nevertheless among the newly reported assemblages one from the lower part of the bambui group stands out as probably the best preserved and most diverse microbiota known from any precambrian unit of south america although paleobiologic studies of the brazilian proterozoic are still in a formative stage recent discoveries are highly promising such as the detection in the work presented here of possible differences 1 between the microfossil sizes in stromatolites of the paranoa and bambui groups 2 in the abundance and size of acritarchs with respect to lithology and facies and 3 in the microfossil assemblages preserved in morphologically distinct stromatolites

analysis of surface deformations over the whole italian territory by interferometric processing of ers envisat and cosmo skymed radar data abstract interferometric processing of series of data acquired over time by synthetic aperture radar sar satellites makes it possible to measure millimetric deformations typically due to landslides subsidence and earthquake or volcanic phenomena and to monitor the stability of terrain and infrastructures despite the unique capability to observe very large areas this technology has been typically applied to the analysis of relatively small sites or specific geophysical phenomena in this work we present the first application of this technology to a national scale project which required the processing through advanced persistent scatterer interferometry psi techniques of about 20 000 sar images acquired from 1992 to 2014 over the whole italian territory by the ers envisat and cosmo skymed satellites the obtained results provide a huge database of surface deformation measurements covering the last 20 years and the whole italian territory which represents an extremely useful and pioneering service for geo hazards mapping and prevention

recent subsidence of the venice lagoon from continuous gps and interferometric synthetic aperture radar 1 coastal regions are increasingly affected by larger storms and rising sea level predicted by global warming models aggravating the situation in the city of venice where tidal induced seasonal flooding coupled with natural and anthropogenic subsidence have been perennial problems in light of accelerated efforts to protect venice from the rise in sea level we assess land subsidence in the venice lagoon over the last decade through a combined analysis of gps position time series from 2001 55 to 2011 00 for four stations installed by the magistrato alle acque di venezia and thousands of observations of insar permanent scatterers using radarsat 1 images from 2003 3 to 2007 85 we determine that the northern lagoon subsides at a rate of 2 3 mm yr whereas the southern lagoon subsides at 3 4 mm yr the city of venice continues to subside at a rate of 1 2 mm yr in contrast to geodetic studies in the last decade of the 20th century suggesting that subsidence has been stabilized the gps results indicate a general eastward tilt in subsidence and that the natural subsidence rate related to the retreat of the adriatic plate subducting beneath the apennines is at least 0 4 0 6 mm yr our combined gps and insar analysis demonstrates high spatial resolution in the vertical direction with a precision of 0 1 0 2 mm yr with respect to a global reference frame continued efforts to secure the city of venice from flooding must also take into account the significant local and regional subsidence rates as well as the expected rise in sea level

assessing short and long time displacements in the venice coastland by synthetic aperture radar interferometric point target analysis 1 the venice lagoon in italy is a unique environment vulnerable to loss in surface elevation relative to the mean sea level we present detailed synthetic aperture radar sar interferometric analyses on persistent point targets for the historical center of venice the tourist area of sottomarina and the zennare farmland close to the southern lagoon edge the selected areas are characterized by different degrees of development and our analyses show the remarkable capability of sar interferometric point target analysis ipta to map land displacement rates in densely urbanized zones and to detect movement information on isolated structures with a mm year accuracy a detailed analysis of the time series from 1992 to 2000 provided by ipta shows that the vertical component of the measured displacements are the superposition of a short timescale generally seasonal movement on the order of 1 cm that is likely related to the fluctuation of environmental variables temperature piezometric head in the aquifer system underlying the lagoon sea lagoon water level and a long term ground deformation associated with building construction the geomorphology of the area and the human development of natural resources if venice is confirmed to be generally stable significant long term subsidence on the order of 4 mm year is detected at the sottomarina coastland the highest displacement rates of up to 8 10 mm year are recorded in the farmland bounding the lagoon margin where the movements are found to be highly site specific

erratum anatomy of the dead sea transform from lithospheric to microscopic scale rewiews of geophysics 2009 47 rg2002 doi 10 1029 2008rg0002264

co seismic slip from the 1995 july 30 mw 8 1 antofagasta chile earthquake as constrained by insar and gps observations summary we analyse radar interferometric and gps observations of the displacement field from the 1995 july 30 mw 8 1 antofagasta chile earthquake and invert for the distribution of slip along the co seismic fault plane using a fixed fault geometry we compare the use of singular value decomposition and constrained linear inversion to invert for the slip distribution and find that the latter approach is better resolved and more physically reasonable separate inversions using only gps data only insar data from descending orbits and insar data from both ascending and descending orbits without the gps data illustrate the complimentary nature of gps and the presently available insar data the gps data resolve slip near gps benchmarks well while the insar provides greater spatial sampling the combination of ascending and descending insar data contributes greatly to the ability of insar to resolve the slip model thereby emphasizing the need to acquire this data for future earthquakes the rake distribution of slip and seismic moment of our preferred model are generally consistent with previous seismic and geodetic inversions although significant differences do exist gps data projected in the radar line of sight los and corresponding insar pixels have a root mean square rms difference of about 3 cm comparison of our predictions of vertical displacement and observed uplift from corraline algae have an rms of 10 cm our inversion and previous results reveal that the location of slip might be influenced by the 1987 mw 7 5 event our analysis further reveals that the 1995 slip distribution was affected by a 1988 mw 7 2 event and might have influenced a 1998 mw 7 0 earthquake that occurred downdip of the 1995 rupture our slip inversion reveals a potential change in mechanism in the southern portion of the rupture consistent with seismic results predictions of the satellite los displacement from a seismic inversion and a joint seismic gps inversion do not compare favourably with the insar observations

geodetic control on recent tectonic movements in the central mediterranean area abstract during the neogene and quaternary the western mediterranean geodynamics was apparently dominated by the nearly eastward migration of the apenninic arc and the associated opening spreading of the back arc basin tyrrhenian sea however during the last 5 my the collision of the arc with the apulian platform led to a dramatic change in the tectonic setting of the area as geological processes require a long period of time to register the displacements of the different blocks it is indispensable to take into account the present day motion given by space geodesy data analysis in order to better constrain the geological models geodetic motions were derived from global positioning system gps satellite laser ranging slr and very long baseline interferometry vlbi observations collected from different networks all the geodetic solutions have been computed and combined at the centre of space geodesy cgs at matera italy the geodetic results show a nne motion of the adriatic plate with a small component of counter clockwise rotation in good agreement with the geological and geophysical observations in the southern tyrrhenian area the lengthening of the matera cagliari baseline should imply that convergence cannot be considered as the driving mechanism for the apenninic subduction process the estimated motion of noto is in quite good agreement with the estimated motion of the african plate

improving deformation models by discounting transient signals in geodetic data 2 geodetic data stress directions and long term strain rates in italy

exploiting uavsar for a comprehensive analysis of subsidence in the sacramento delta abstract the sacramento san joaquin delta like other heavily engineered deltas throughout the world has undergone substantial subsidence since the late 1800s when the natural estuary was leveed to form islands today islands within the delta have subsided to the point where most lie below mean sea level long term sustainability of the delta requires reversal of subsidence but spatially comprehensive maps of subsidence have not been available to inform and monitor remediation reported here is the first spatially dense map of recent subsidence rates across the delta based on synthetic aperture radar interferometry and constrained by gnss observations the analysis uses a temporally dense and spatially overlapping set of data acquired by the uninhabited aerial vehicle sar uavsar sensor in 2009 2015 on average the delta is subsiding by 9 2 4 4 mm yr with high variability even at the sub island scale including peak subsidence of 160 4 4 mm yr occurring just inland of the levee of the westernmost island and average subsidence of 11 mm yr along the planned path of water conveyance tunnels through the delta the results are compared to local sea level rise slr measured at a tidal gauge in san francisco bay to show that subsidence is currently the dominant contributor to local relative sea level rise rslr by nearly a factor of five based on recently measured and modeled acceleration of slr subsidence in the delta is likely to dominate rslr until the middle of the 21th century

contemporary uplift of the sierra nevada western united states from gps and insar measurements modern space geodesy has recently enabled the direct observation of slow geological processes that move and shape earth s surface including plate tectonics and crustal strain accumulation that leads to earthquakes more elusive has been the direct observation of active mountain growth because geodetic measurements have larger uncertainties in the vertical direction while mountain growth is typically very slow for the sierra nevada of california and nevada western united states the history of elevation is complex exhibiting features of both ancient 40 60 ma and relatively young 3 ma elevation here we exploit the complementary strengths of high precision three component point positions from the gps and blanket coverage line of sight measurements from interferometric synthetic aperture radar insar to show that contemporary vertical motion of the sierra nevada is between 1 and 2 mm yr the motion is upward with respect to earth s center of mass and with respect to a relatively stable eastern nevada indicating generation of relief and uplift against gravity uplift is distributed along the entire length of the range between latitude 35 n and 40 n and is not focused near localized seismically imaged mantle downwellings these results indicate that the modern episode of sierra nevada uplift is still active and could have generated the entire modern range in 3 m y

current sierra nevada north america motion from very long baseline interferometry implications for the kinematics of the western united states we use geodetic measurements from very long baseline interferometry to estimate the motion of the sierra nevadan microplate which is composed of the sierra nevada and the great valley the motion of the sierra nevadan microplate relative to the north american plate is described by a right handed rotation of 0 61 m y about lat 32 n long 128 w this euler pole lies only 10 southwest of the sierra nevadan microplate and predicts a significant counterclockwise rotation about a local vertical axis it further predicts a velocity of the eastern edge of the sierra nevada at 38 0 n 119 3 w relative to stable north america of 11 1 mm yr toward n36 3 w quoted uncertainties are plus or minus one standard error which accounts for about one fourth of the velocity between the pacific and north american plates and is 25 clockwise of many prior estimates the velocity nearly parallels the boundary between the sierra nevada and the great basin which implies that current motion within the great basin results in a rotational noncoaxial deformation we use this velocity to estimate how motion is distributed across the broad deforming zone taking up pacific north america plate motion we find that the vector sum of strike slip along the san andreas fault and motion of the sierra nevada relative to stable north america taken up by deformation within the great basin differs little from the pacific north america plate velocity the difference can be described at 36 n along the san andreas fault by a vector of 6 mm yr directed toward n20 w this vector resolves into components of 5 mm yr parallel to the fault and 2 mm yr perpendicular to the fault with 95 confidence intervals of 0 to 10 mm yr and 1 to 5 mm yr respectively the component perpendicular to the fault is several times smaller than found in prior studies and places a small upper bound on fault perpendicular shortening we conclude that motion previously inferred to be taken up by deformation other than strike slip along the san andreas fault or deformation within the great basin is much smaller than previously thought

rapid drought induced land subsidence and its impact on the california aqueduct abstract the central valley in california is characterized by a semi arid climate prone to droughts a variable surface water supply and immense agricultural areas dependent on groundwater irrigation the groundwater is stored in a complex aquifer system composed of alternating layers of coarse sediments and fine grained sediments acting as confining materials groundwater fluctuations are coupled with both the elastic and inelastic land surface deformation historically observed in the central valley surface deformation poses a hazard to the california aqueduct which supports central valley agriculture and large urban populations in southern california the risk of reduced aqueduct efficacy and expensive repairs compels water resource managers to carefully monitor land deformation in the valley a persistent drought in the region began in 2012 intensified in 2014 and was abruptly alleviated by a wet period from dec 2016 to feb 2018 nasa s uavsar l band synthetic aperture radar acquired 31 high resolution radar images between may 2013 and nov 2018 the interferometric phase difference between acquisitions is used to develop a time series of vertical displacement and identify and track a rapidly forming subsidence feature adjacent to the california aqueduct the surface area of the feature that subsided 10 cm or more by the end of the time series reaches 4452 ha and a 10 5 km segment of the aqueduct this study also incorporates extensometer measurements precise leveling surveys sentinel 1a displacement concurrent water elevation data well construction reports nearby extensometer measurements aquifer material characterization and environmental conditions spatiotemporal data availability limits the appropriateness of calculations and models able to be performed for different sites along the aqueduct we aim to offer insight into heterogeneous subsurface properties and mechanics estimate the permanent loss of aquifer storage volume and identify additional data that would aid water management

owen fracture zone the arabia india plate boundary unveiled we surveyed the owen fracture zone at the boundary between the arabia and india plates in the nw indian ocean using a high resolution multibeam echo sounder owen cruise 2009 for search of active faults bathymetric data reveal a previously unrecognized submarine fault scarp system running for over 800 km between the sheba ridge in the gulf of aden and the makran subduction zone the primary plate boundary structure is not the bathymetrically high owen ridge but is instead a series of clearly delineated strike slip fault segments separated by several releasing and restraining bends despite an abundant sedimentary supply by the indus river flowing from the himalaya fault scarps are not obscured by recent deposits and can be followed over hundreds of kilometres pointing to very active tectonics the total strike slip displacement of the fault system is 10 12 km indicating that it has been active for the past 3 to 6 ma if its current rate of motion of 3 1 mm yr 1 has remained stable we describe the geometry of this recent fault system including a major pull apart basin at the latitude 20 n and we show that it closely follows an arc of small circle centred on the arabia india pole of rotation as expected for a transform plate boundary

reply to comment by p teatini et al on recent subsidence of the venice lagoon from continuous gps and interferometric synthetic aperture radar 1 unlike most published scientific comments the comment submitted by p teatini l tosi and t strozzi on bock et al 2012 does not dispute the scientific merits of our study but rather reinforces its approach and main results regarding venice subsidence their main points appear to be that our study 1 did not cite the two last papers that they published tosi et al 2010 teatini et al 2012a 2 received considerable attention worldwide for a rather small level of subsidence 3 used a methodology that is not original 4 misrepresented some of their earlier work and 5 published uncertainties that were too optimistic

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

itrf2005 a new release of the international terrestrial reference frame based on time series of station positions and earth orientation parameters 1 unlike the past international terrestrial reference frame itrf versions where global long term solutions were combined the itrf2005 uses as input data time series weekly from satellite techniques and 24 h session wise from very long baseline interferometry of station positions and daily earth orientation parameters eops the advantage of using time series of station positions is that it allows to monitor station non linear motion and discontinuities and to examine the temporal behavior of the frame physical parameters namely the origin and the scale the itrf2005 origin is defined in such a way that it has zero translations and translation rates with respect to the earth center of mass averaged by the satellite laser ranging slr time series spanning 13 years of observations its scale is defined by nullifying the scale and its rate with respect to the very long baseline interferometry vlbi time series spanning 26 years of observations the itrf2005 orientation at epoch 2000 0 and its rate are aligned to the itrf2000 using 70 stations of high geodetic quality the estimated level of consistency of the itrf2005 origin at epoch 2000 0 and its rate with respect to the itrf2000 is respectively 0 1 0 8 5 8 mm and 0 2 0 1 1 8 mm yr along the x yand z axis we estimate the formal errors on these components to be 0 3 mm and 0 3 mm yr we believe that this low level of agreement between the two frame origins is most probably due to the poor slr network geometry and its degradation over time the itrf2005 combination involving 84 co location sites revealed a scale inconsistency of 1 ppb 6 3 mm at the equator at epoch 2000 0 and 0 08 ppb yr between the slr and vlbi long term solutions as obtained by the stacking of their respective time series possible causes of this inconsistency may include the poor slr and vlbi networks and their co locations local tie uncertainties systematic effects and possible inconsistent model corrections used in the data analysis of both techniques for the first time of the itrf history the itrf2005 rigorous combination provides self consistent series of eops including polar motion from vlbi and satellite techniques and universal time and length of day from vlbi only a velocity field of 152 sites with an error less than 1 5 mm yr is used to estimate absolute rotation poles of 15 tectonic plates that are consistent with the itrf2005 frame this new absolute plate motion model supersedes and significantly improves that of the itrf2000 which involved six major tectonic plates citation altamimi z x collilieux j legrand b garayt and c boucher 2007 itrf2005 a new release of the international terrestrial reference frame based on time series of station positions and earth orientation parameters j geophys res 112 b09401

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

vertical land motion and relative sea level changes along the coastline of brest france from combined space borne geodetic methods abstract in spite of the recent advances and the current perspectives of satellite radar altimetry to reach the coastline and monitor coastal sea level changes this space borne technology remains geocentric by essence in contrast the quantity that matters for coastal management and society is relative sea level that is the sea level relative to the land as measured by conventional tide gauges however two important issues are associated with the use of tide gauges first supplemental information is required to separate vertical land motion from ocean climate signals in tide gauge records and hence to understand the causes of future coastal sea level changes and their relative importance this can be provided by space borne geodetic techniques for instance installing a permanent global positioning system gps antenna at the tide gauge second vertical land motion can show local spatial patterns which limits the spatial validity of the point wise information at the gps station using interferometry synthetic aperture radar insar and high precision gps data the above mentioned limitations were addressed in the case study of brest france our findings show that over the past decades brest and its surroundings are overall stable in agreement with the geological setting except for the embankment areas of the commercial and military harbours the gps calibrated insar results were then further combined with geocentric satellite radar altimetry data to obtain relative sea level trends along the brest coastline with an unprecedented high spatial resolution of 200 m our approach is applicable beyond the case study of brest especially in coastal areas where tide gauge data are not available provided satellite data are

dynamics of slow moving landslides from permanent scatterer analysis high resolution interferometric synthetic aperture radar insar permanent scatterer data allow us to resolve the rates and variations in the rates of slow moving landslides satellite to ground distances range changes on landslides increase at rates of 5 to 7 millimeters per year indicating average downslope sliding velocities from 27 to 38 millimeters per year time series analysis shows that displacement occurs mainly during the high precipitation season during the 1997 1998 el nino event rates of range change increased to as much as 11 millimeters per year the observed nonlinear relationship of creep and precipitation rates suggests that increased pore fluid pressures within the shallow subsurface may initiate and accelerate these features changes in the slope of a hill resulting from increases in the pore pressure and lithostatic stress gradients may then lead to landslides

stream incision tectonics uplift and evolution of topography of the sierra nevada california abstract stream incision faulting thermochronologic and geobarometric data suggest that sierra nevada topography is a consequence of two periods of uplift stream incision of up to 1 km has occurred since 5 ma maximum eocene miocene incision was 150 m uplift of the sierra nevada westward tilting stream incision and east down normal and dextral faulting along the present eastern escarpment of the range began at 5 ma estimates of late cenozoic crestal rock uplift for different areas in the sierra nevada range from 1440 to 2150 m low summit erosion rates suggest that the rock uplift approximates the surface uplift of crestal summits tertiary stream gradients were lower than modern ones suggesting that the bottoms of the canyons have been uplifted in the late cenozoic and that the mean elevation of the sierra nevada has increased the elevation of pre cenozoic basement rocks above the base of tertiary paleochannels ranges from 1000 m in the south and

textural and geochemical analysis of chalcopyrite galena and sphalerite across the mount isa cu to pb zn transition implications for a zoned cu pb zn system abstract the genesis of the mount isa cu pb zn system northern australia is highly debated three metallogenic models have previously been proposed to explain the close spatial relationship between a world class cu and pb zn deposit 1 ca 1650 ma syngenetic pb zn mineralisation that has been re mobilised and overprinted by ca 1520 ma epigenetic cu mineralisation 2 ca 1650 ma syn sedimentary cu pb zn mineralisation 3 ca 1520 ma epigenetic cu pb zn mineralisation to assess the viability of these models detailed petrography and core logging was completed on numerous samples across eight sections of drill core that intersect both cu and pb zn mineralisation this was accompanied by the analysis of trace elements in chalcopyrite galena and sphalerite from various samples across the lateral transition from cu to pb zn rich mineralisation across the cu to pb zn transition there is a primary change in host lithology from cu rich silica dolomite breccia to highly stratiform pb zn rich carbonaceous carbonate rich and fine grained pyrite rich shale petrography suggests that sphalerite galena and chalcopyrite co crystallised consistently enveloping and or replacing pre mineralisation silica dolomite siderite calcite arsenopyrite fine and coarse grained pyrite from cu to pb zn rich mineralisation sphalerite and galena transition from micro inclusions primarily located within coarse grained chalcopyrite to dominant fine to coarse grained components that infill around deformed carbonaceous shale and selectively replace carbonate rich and fine grained pyrite rich shale chalcopyrite transitions from a coarse grained component that replaces silica dolomite alteration to an uncommon medium to fine grained component residing within stratabound pb zn mineralisation trace element trends demonstrate that as pb zn mineralisation is approached the concentrations of bi in chalcopyrite cd se te bi in galena and bi and co in sphalerite decrease or are relatively depleted conversely the concentrations of pb in chalcopyrite sb in galena and pb sb and ag in sphalerite increase or are relatively enriched these trends are consistent with a temperature gradient between cu and pb zn mineralisation during ore emplacement the sphalerite ggimfis geothermometer yields a median homogenisation temperature of 343 44 c consistent with previous temperature estimates of cu mineralisation silica dolomite formation and chlorite alteration an epigenetic and coeval cu pb zn model is favoured where a slight temperature gradient

a new project to monitor land subsidence in the northern venice coastland italy the paper deals with the implementation of a levelling and global positioning system gps network to control land subsidence in the coastal area north of the venice lagoon about 480 km of levelling lines with 527 benchmarks 45 of which suited for differential gps measurements were established in 2004 a complete survey of the net was carried out in 2004 soon after its establishment the 2004 records have been compared with previous scattered data obtained by the use of levelling surveys dgps and sar interferometry the results show a trend in land settlement that increases from the lagoon margin to the north and jeopardize the venice coastland groundwater withdrawals for domestic agricultural and health spas uses peat oxidation of reclaimed marshlands for farming natural consolidation of the holocene deposits and tectonics of the pre quaternary basement are the causes of land subsidence in the study area since most of the area lies below the mean sea level and on account of the expected sea level rise due to global change a detailed monitoring of land displacements in the near future will be of paramount importance to plan necessary works for coastland protection

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

decoding the origins of vertical land motions observed today at coasts in recent decades geodetic techniques have allowed detecting vertical land motions and sea level changes of a few millimetres per year based on measurements taken at the coast tide gauges on board of satellite platforms satellite altimetry or both global navigation satellite system here contemporary vertical land motions are analysed from january 1993 to july 2013 at 849 globally distributed coastal sites the vertical displacement of the coastal platform due to surface mass changes is modelled using elastic and viscoelastic green s functions special attention is paid to the effects of glacial isostatic adjustment induced by past and present day ice melting various rheological and loading parameters are explored to provide a set of scenarios that could explain the coastal observations of vertical land motions globally in well instrumented regions predicted vertical land motions explain more than 80 per cent of the variance observed at scales larger than a few hundred kilometres residual vertical land motions show a strong local variability especially in the vicinity of plate boundaries due to the earthquake cycle significant residual signals are also observed at scales of a few hundred kilometres over nine well instrumented regions forming observation windows on unmodelled geophysical processes this study highlights the potential of our multitechnique database to detect geodynamical processes driven by anthropogenic influence surface mass changes surface loading and glacial isostatic adjustment and tectonic activity including the earthquake cycle sediment and volcanic loading as well as regional tectonic constraints future improvements should be aimed at densifying the instrumental network and at investigating more thoroughly the uncertainties associated with glacial isostatic adjustment models

land subsidence in houston correlated with flooding from hurricane harvey abstract hurricane harvey caused unprecedented flooding and socioeconomic devastation in eastern texas with high winds elevated storm tide and record rainfall the flooded area is mapped using the radar backscattering difference between sentinel 1a b satellite acquisitions spanning the event which provides a snapshot of standing water at the time of image acquisition we find vast areas outside of designated flood hazard zones are overwhelmed furthermore we map pre cyclone land subsidence using multitemporal interferometric processing of large sar datasets acquired by advanced land observation satellite alos and sentinel 1a b satellites we find that subsidence of up to 49 mm yr and 34 mm yr during the alos jul 2007 jan 2011 and sentinel 1a b dec 2015 to aug 2017 acquisition periods affect various parts of houston galveston area we conclude that 85 of the flooded area subsided at a rate 5 mm yr we suggest that subsidence affected flood severity by modifying base flood elevations and topographic gradients supported by the chi square test of independence this work highlights the importance of incorporating insar measurements of land subsidence in flood resilience strategies

cenozoic tectonic and topographic evolution of the northern sierra nevada california through stable isotope paleoaltimetry in volcanic glass we determine the paleoelevation of the northern sierra nevada california in the oligocene based on hydrogen stable isotope compositions of meteoric water preserved within volcanic glass from ignimbrites sampled across the range a 48 decrease in the isotopic composition of hydrated glass from ignimbrites located near paleosea level to ignimbrites 100 km to the east refl ects the effect of ancient high topography on precipitation these data show that 31 28 ma ago the northern sierra nevada had a steep western gradient and elevations similar to the present this study placed in the context of other paleoaltimetry studies suggests that the range was a high topographic feature throughout the cenozoic and that the majority of uplift occurred in the late cretaceous to early cenozoic much earlier than some studies have proposed

high nonlinear urban ground motion in manila philippines from 1993 to 2010 observed by dinsar implications for sea level measurement abstract in coastal low lying urban areas vertical ground motions can significantly exacerbate the hazards related to sea level rise however their spatial extent their temporal evolution and even sometimes their existence are often poorly known this study aims to monitor variable urban ground motion uplift and subsidence from 1993 to 2010 in the metropolitan area of manila philippines because high subsidence rates have been reported in this city in previous studies conventional differential sar interferometry dinsar was applied with an adapted stacking procedure to the archive of ers and envisat satellite images to produce surface deformation velocity maps for different periods the results showed that the city is locally affected by vertical ground motions on the order of 15 cm yr moreover the spatio temporal evolution of the ground motion phenomena is highly nonlinear these results are in good agreement with previous studies focused on groundwater use in manila and in the marikina fault valley suggesting a plausible interpretation of the processes causing surface motion incidentally the ground motions are affecting the locations of several geodetic instruments including a tide gauge with sea level records starting in 1902 two permanent gps global positioning system stations and a doris doppler orbitography and radiopositioning integrated by satellite station a major implication of those large and locally variable ground motions is that they impede the use of the nearby gps and doris data to correct the tide gauge records and to derive robust sea level trends associated with climate change

are long tide gauge records in the wrong place to measure global mean sea level rise ocean dynamics land motion and changes in earth s gravitational and rotational fields cause local sea level change to deviate from the rate of global mean sea level rise here we use observations and simulations of spatial structure in sea level change to estimate the likelihood that these processes cause sea level trends in the longest and highest quality tide gauge records to be systematically biased relative to the true global mean rate the analyzed records have an average twentieth century rate of approximately 1 6 mm yr but based on the locations of these gauges we show that the simple average underestimates the twentieth century global mean rate by 0 1 0 2 mm yr given the distribution of potential sampling biases we find that 1 probability that observed trends from the longest and highest quality tide gauge records are consistent with global mean rates less than 1 4 mm yr

surface uplift uplift of rocks and exhumation of rocks uplift of the surface of mountain belts requires forces that are comparable in magnitude to those associated with plate motion and therefore determination of rates of surface uplift could provide important information on the dynamics of mountain ranges rates of uplift of the surfaces of mountain ranges have not however been quantified sufficiently well that they provide useful constraints on those processes many reports off surface uplift in mountain ranges are based on mistaking exhumation of rocks or uplift of rocks for surface uplift and provide no information whatsoever on the rates of surface uplift

spatial variability of late holocene and 20th century sea level rise along the atlantic coast of the united states accurate estimates of global sea level rise in the pre satellite era provide a context for 21 st century sea level predictions but the use of tide gauge records is complicated by the contributions from changes in land level due to glacial isostatic adjustment gia we have constructed a rigorous quality controlled database of late holocene sea level indices from the u s atlantic coast exhibiting subsidence rates of 0 8 mm a 1 in maine increasing to rates of 1 7 mm a 1 in delaware and a return to rates 0 9 mm a 1 in the carolinas this pattern can be attributed to ongoing gia due to the demise of the laurentide ice sheet our data allow us to defi ne the geometry of the associated collapsing proglacial forebulge with a level of resolution unmatched by any other currently available method the corresponding rates of relative sea level rise serve as background rates on which future sea level rise must be superimposed we further employ the geological data to remove the gia component from tide gauge records to estimate a mean 20 th century sea level rise rate for the u s atlantic coast of 1 8 0 2 mm a 1 similar to the global average however we fia distinct spatial trend in the rate of 20 th century sea level rise increasing from maine to south carolina this is the fi rst evidence of this phenomenon from observational data alone we suggest this may be related to the melting of the greenland ice sheet and or ocean steric effects

subsidence along the atlantic coast of north america insights from gps and late holocene relative sea level data the atlantic coast of north america is increasingly affected by flooding associated with tropical and extratropical storms exacerbated by the combined effects of accelerated sea level rise and land subsidence the region includes the collapsing forebulge of the laurentide ice sheet high quality records of late holocene relative sea level rsl rise are now available allowing separation of long term glacial isostatic adjustment induced displacement from modern vertical displacement measured by gps we compare geological records of late holocene rsl to present day vertical rates from gps for many coastal areas there is no significant difference between these independent data exceptions occur in areas of recent excessive groundwater extraction between virginia 38 n and south carolina 32 5 n the present day subsidence rates in these areas are approximately double the long term geologic rates which has important implications for flood mitigation tide gauge records therefore should be used with caution for studying sea level rise in this region

effect of annual signals on geodetic velocity 1 our analysis of global positioning system gps site coordinates in a global reference frame shows annual variation with typical amplitudes of 2 mm for horizontal and 4 mm for vertical with some sites at twice these amplitudes power spectrum analysis confirms that gps time series also contain significant power at annual harmonic frequencies with spectral indices 1 2 which indicates the presence of repeating signals van dam et al 2001 showed that a major annual component is induced by hydrological and atmospheric loading unless accounted for we show that annual signals can significantly bias estimation of site velocities intended for high accuracy purposes such as plate tectonics and reference frames for such applications annual and semiannual sinusoidal signals should be estimated simultaneously with site velocity and initial position we have developed a model to calculate the level of bias in published velocities that do not account for annual signals simultaneous estimation might not be necessary beyond 4 5 years as the velocity bias rapidly becomes negligible minimum velocity bias is theoretically predicted at integer plus half years as confirmed by tests with real data below 2 5 years the velocity bias can become unacceptably large and simultaneous estimation does not necessarily improve velocity estimates which rapidly become unstable due to correlated parameters we recommend that 2 5 years be adopted as a standard minimum data span for velocity solutions intended for tectonic interpretation or reference frame production and that we be skeptical of geophysical interpretations of velocities derived using shorter data spans

subdivision and correlation of late precambrian sequences in australia abstract the diversity of the australian precambrian record is used to empirically assess the application of all available techniques of correlation of late precambrian rocks lithofacies isotopic ages palaeontology and palaeomagnetism within the framework of latest lithostratigraphic geochronologic correlation charts lithostratigraphy is the main tool for intrabasinal correlation and mapping but isotopic ages will continue for some time yet to provide the main criteria for interregional correlation lithostratigraphic correlation is demonstrated over hundreds of kilometres but is generally constrained by tectonic controls to individual major crustal blocks climatic markers such as tillites may be correlated interregionally over thousands of kilometres the most exciting recent development in platform geochronology is the application of u pb zircon dating to fine grained tuffs illite may provide reliable minimum estimates but can be shown to be up to 150 ma too young glauconite and rb sr total rock shale ages have provided useful broad age estimates of sequences for which better methods are unavailable but only when based on cautious assessment and multiple sampling their ages may be either minimum or maximum stromatolites continue to demonstrate their potential for broad correlation when based on rigorous taxonomic study but the framework of time ranges of known taxa must be expanded for stromatolites to achieve their full potential especially for rocks older than 1000 ma acritarchs in black shales provide diverse and complex assemblages with excellent correlation potential but once again the australian taxonomic framework is still inadequate black cherts contain an evolutionarily conservative biota with only limited correlation potential recent palaeomagnetic studies based on both apwp and magnetostratigraphy demonstrate excellent potential for detailed correlations down to at least 1700 ma old however the present chronologically calibrated data base is sparse and must be supplemented by many more detailed studies through thick continuous rock sequences spanning substantial intervals of time the value of multidisciplinary correlation is elegantly demonstrated by very detailed and unambiguous correlation of combined palaeomagnetic isotopic age and stromatolite data across the 1700 ma mcarthur basin previous regional lithostratigraphic correlations have been conclusively and significantly revised with major implications to regional palaeogeography

southern california permanent gps geodetic array spatial filtering of daily positions for estimating coseismic and postseismic displacements induced by the 1992 landers earthquake the june 28 1992 m w 7 3 landers california earthquake was the first earthquake to be surveyed by a continuously operating global positioning system gps array the coordinate time series of seven sites are evaluated for station displacements during an interval of 100 days centered on the day of the earthquake we employ a new spatial filtering technique that removes common mode errors from the coordinate time series this approach provides precise estimates of site specific displacements compared to the cumbersome method of analyzing baselines between pairs of stations all sites indicate significant coseismic horizontal displacements of 5 65 mm with uncertainties of 1 2 mm horizontal displacements are in general agreement with elastic dislocation models in particular for sites closer to the epicenter vertical displacements range from 13 to 7 mm with uncertainties of 2 4 mm the observed vertical displacements in all cases show 5 10 mm more subsidence than expected from geodetic and seismic geologic models significant postseismic horizontal displacements totaling 6 2 mm 10 20 of the coseismic displacement are detected at the three sites closest to the epicenter these displacements are modeled as a short term exponential relaxation with a decay time of 22 10 days superimposed on a longer term linear interseismic trend scaling the observed coseismic and postseismic displacements at one of the sites with the distance to the epicenter provides a measure of site strain which agrees well with the direction and magnitude determined from more precise laser strain meter data the time series do not show any detectable preseismic displacements

mapping regional land displacements in the venice coastland by an integrated monitoring system abstract an original integrated monitoring method is designed to infer an accurate and reliable figure of regional land displacements in coastal areas where the presence of internal waters wetlands farmlands urban and industrial centers usually reduces the efficiency of single ground based and satellite based measuring techniques five different methods i e spirit leveling differential global positioning system dgps continuous gps cgps interferometric synthetic aperture radar insar and interferometric point target analysis ipta are integrated into a subsidence integrated monitoring system sims to overcome the limits characterizing each technique the sims has been used over the past decade to provide a new image of the land displacements in the venice region the result exhibits a resolution never obtained before the central lagoon including the city of venice shows a general stability while the northern and southern lagoon extremities and their related catchment sectors sink with serious rates averaging 3 to 5 mm year the sinking rates increase up to 10 15 mm year in the coastland south of the lagoon relatively small uplifts less than 1 mm year are observed at the alpine foothills and in a wide area comprised between the euganean hills and the lagoon the observed land displacements have been associated to the geological features of the study region i e tectonics seismicity differential consolidation of the middle upper pleistocene and holocene deposits and to anthropogenic activities such as land reclamation and groundwater withdrawal

deformation and seismicity in the coso geothermal area inyo county california observations and modeling using satellite radar interferometry interferometric synthetic aperture radar insar data collected in the coso geothermal area eastern california during 1993 1999 indicate ground subsidence over a 50 km 2 region that approximately coincides with the production area of the coso geothermal plant the maximum subsidence rate in the peak of the anomaly is 3 5 cm yr 1 and the average volumetric rate of subsidence is of the order of 10 6 m 3 yr 1 the radar interferograms reveal a complex deformation pattern with at least two irregular subsidence peaks in the northern part of the anomaly and a region of relative uplift on the south we invert the insar displacement data for the positions geometry and relative strengths of the deformation sources at depth using a nonlinear least squares minimization algorithm we use elastic solutions for a prolate uniformly pressurized spheroidal cavity in a semi infinite body as basis functions for our inversions source depths inferred from our simulations range from 1 to 3 km which corresponds to the production depths of the coso geothermal plant underpressures in the geothermal reservoir inferred from the inversion are of the order of 0 1 1 mpa except a few abnormally high underpressures that are apparently biased toward the small source dimensions analysis of the insar data covering consecutive time intervals indicates that the depths and or horizontal extent of the deformation sources may increase with time this increase presumably reflects increasing volumes of the subsurface reservoir affected by the geothermal exploitation we show that clusters of microearthquakes associated with the geothermal power operation may result from perturbations in the pore fluid pressure as well as normal and shear stresses caused by the deflation of the geothermal reservoir

understanding the subsidence process of a quaternary plain by combining geological and hydrogeological modelling with satellite insar data the acque albule plain case study abstract this paper focuses on a multidisciplinary study carried out in an urban area affected by subsidence and related structural damages the study area is located about 20 km east of rome italy and is characterised by relevant groundwater exploitation for various purposes as well as by the presence of compressible soils immediately below the ground level extensive processing at different scales of sar satellite images ers and envisat provided by esa in the frame of a cat 1 project by means of a dinsar technique was performed the time histories of ground displacements have been analysed in combination with a detailed geological setting of the study area and with the hydrogeological changes occurred in the last decades as the response to the anthropic stress based on a large piezometric dataset this comprehensive dataset allowed us to describe the space and time distributions of the subsidence process the spatial pattern and deformation rate change is attributed to the following causes i the changes in the groundwater levels due to the intensification of mine exploitation requiring dewatering operations and ii the distribution and thickness of recent compressible deposits specifically it is derived that the groundwater level variations drive the timing of subsidence triggering over the area whereas the local geological conditions control the magnitude of the deformation process

southern california permanent gps geodetic array error analysis of daily position estimates and site velocities we analyze time series of daily positions estimated from data collected by 10 continuously monitoring global positioning system gps sites in southern california during the 19 month period between the june 28 1992 mw 7 3 landers and january 17 1994 mw 6 7 northridge earthquakes each time series exhibits a linear tectonic signal and significant colored noise spectral power at frequencies in the range 5 yr 1 to 0 5 d 1 is dominated by white noise or possibly fractal white noise and is several orders of magnitude higher than what would be expected from random walk noise in this short period range attributed by others to geodetic monument motions estimating a single slope for the time series power spectra suggests fractal white noise processes with spectral indices of about 0 4 site velocity uncertainties assuming this fractal white noise model are 2 4 times larger than uncertainties obtained assuming a purely white noise model a combination white noise plus flicker noise spectral index of 1 model also fits the data and suggests that the velocity uncertainties should be 3 6 times larger than for the white noise model we cannot adequately distinguish between these two noise models nor can we rule out the possibility of a random walk signal at the lowest frequencies these questions await the analysis of longer time series in any case reducing the magnitude of low frequency colored noise is critical and appears to be best accomplished by building sites with deeply anchored and braced monuments otherwise rate uncertainties estimated from continuous gps measurements may not be improved significantly compared to those estimated from infrequent campaign mode measurements

sea level change in the northern mediterranean sea from long period tide gauge time series abstract the oldest tide gauge observations date back to the 18th century although globally they are available in limited number these centuries old sea level time series are the only data records providing information on the long period rates of change of the mean ocean surface knowledge of the past sea level behavior can contribute key insights to the understanding of climate change impacts we highlight the greatest importance of monitoring sea level changes at all spatial scales from global to local using terrestrial and space techniques and outline the physical processes natural and man induced responsible for such changes in general tide gauge data are made available through different archiving facilities serving both international and national developments tide gauges measure local sea level relative to a benchmark on land hence correctly interpreting these observations is challenging since it demands among other requirements a proper knowledge of vertical land motions at the stations in general it is not easy to find well documented historical data moreover benchmarks were not frequently leveled for more than two decades space geodetic techniques such as gnss global navigation satellite system and insar interferometric synthetic aperture radar have provided the opportunity to accurately position points in the surroundings of tide gauge sites potentially giving rise to a large amount of information however despite the availability of these techniques the evolution of the international efforts aiming at realizing consistent observational infrastructures for sea level networks is undergoing only a slow development in the mediterranean area there are a few centennial tide gauge records our study focuses on the time series of alicante in spain marseille in france genoa marina di ravenna formerly porto corsini venice and trieste in italy after briefly reviewing the gauge types presently in use for sea level measurements a comprehensive historical description is given for each time series which may assist understanding an assessment of the problems these stations have experienced over more than one century of operations two italian stations marina di ravenna and venice are affected by both natural and anthropogenic subsidence the latter was particularly intense during a few decades in the 20th century because of ground fluid withdrawal for these two stations we have retrieved leveling data of benchmarks close to the tide gauges from the end of the 19th century and for the last couple of decades we have evaluated gps and insar heights in close proximity to the stations the gps global positioning system and sar results were carefully compared modeling of the long period non linear behavior of subsidence was successfully accomplished by using an ensemble of leveling gps and sar data after removing the vertical land motions in venice and marina di ravenna and the inverted barometer effect at all the sites the linear long period sea level rates were estimated the results are in excellent agreement ranging between 1 2 and 1 3 mm year for the overall period from the last decades of the 19th century till 2012 the associated errors computed by accounting for serial autocorrelation are of the order of 0 2 0 3 mm year for all stations except alicante for which the error turns out to be 0 5 mm year our estimated rates for the northern mediterranean a relatively small regional sea are slightly lower than the global mean rate 1 7 0 2 mm year recently published in the ipcc ar5 intergovernmental panel on climate change 5th assessment report church et al 2013 but close enough if uncertainties are taken into account it is known that mediterranean stations had always had lower trends than the global average ones our regional results however are in close agreement with the global mean rate 1 2 mm year published by hay et al 2015 which is currently being discussed by the oceanographic community see for example hamlington and thompson 2015 the six time series were also analyzed by means of the eof empirical orthogonal functions technique over the 1934 2012 common period as a result about 50 of the total variance is explained by the first mode which is characterized by a coherent behavior of the six stations

sustained water loss in california s mountain ranges during severe drought from 2012 to 2015 inferred from gps drought struck california during 7 of the 9 years from 2007 to 2015 reducing the state s available water resources pumping of central valley groundwater has produced spectacular land subsidence uplift of the adjacent sierra nevada mountains has been proposed to be either tectonic uplift or solid earth s elastic response to unloading of central valley groundwater we find that of the 24 mm of uplift of the sierra nevada from october 2011 to october 2015 just 5 mm is produced by central valley groundwater loss less than 2 mm is tectonic uplift and 17 mm is solid earth s elastic response to water loss in the sierra nevada we invert gps vertical displacements recording solid earth s elastic response to infer changes in water storage across the western u s from january 2006 to october 2017 we find water changes to be sustained over periods of drought or heavy precipitation the sierra nevada lost 15 19 km3 of water during drought from october 2006 to october 2009 gained 18 14 km3 of water during heavy precipitation from october 2009 to october 2011 and lost 45 21 km3 of water during severe drought from october 2011 to october 2015 95 confidence limits such large changes are not in hydrology models snow accumulation in october is negligible and long term soil moisture change is small we infer that there must be large loss of either deep soil moisture or groundwater in river alluvium and in crystalline basement in the sierra nevada the results suggest there to be parching of water in the ground during the summer of years of drought and seeping of melting snow into the sierra nevada in the spring of years of heavy precipitation

variety and origin of magmas on shatsky rise northwest pacific ocean 1 shatsky rise consists of thick 30 km maximum basaltic crust with various geochemical compositions geochemistry data indicate that four magma types exist on the plateau namely normal low ti high nb and u1349 types the normal type is the most abundant in volume and appears on all three large edifices of the plateau tamu ori and shirshov massifs composition of the normal type is similar to normal mid ocean ridge basalt n morb composition but with slight relative enrichment of the more incompatible elements the low ti type is distinguished from the normal type basalt by slightly lower ti content at a given mgo composition of the high nb type is characterized by distinctively high contents of incompatible trace elements u1349 type basalts are composed of more primitive and depleted compositions compared with the others the normal type basalts constitute 94 of the lava units of the oldest tamu massif and non normal types i e the other three types basalts comprise 57 on the younger ori massif implying that geochemical compositions may have become heterogeneous with time petrological examination demonstrates that compositions of the normal low ti and high nb type basalts evolved through fractional crystallization of olivine plagioclase and augite in shallow magma chambers 200 mpa model calculations of immobile trace elements estimate that the normal type basalt can be formed by 15 melting of a depleted mantle source in the presence of residual garnet this degree of melting is similar to n morb but the larger effect of residual garnet during petrogenesis implies that a greater depth of melting

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

the rift like structure and asymmetry of the dead sea fault abstract whereas the dead sea fault is a major continental transform active since ca 13 18 ma ago it has a rift like morphology along its southern part it has been argued that this results from a transtensional component active since 5 ma ago due to a regional plate kinematics change we present the results of 3d laboratory experiments carried out to test this hypothesis and to explore its consequences for the structure and morphology of the dead sea fault we conclude that a two stage tectonic history invoking a first stage of pure strike slip and a second stage marked by the addition of a minor transtensional component is consistent with most of the striking geological and geophysical features of the dead sea fault the structural and morphological asymmetry of the dead sea fault can be explained by a transverse horizontal shear in the ductile lower crust below the transform zone a large scale heating event of the arabian mantle is not required to explain these features of the dead sea fault

terrasar x reveals the impact of the mobile barrier works on venice coastland stability land subsidence and eustacy concurred to make the relative sea level in venice italy 23 cm higher over the last century in order to protect the city and its lagoon environment from increased flooding a series of mobile barriers are under construction at the three inlets of lido malamocco and chioggia connecting the adriatic sea to the inner water body since 2003 work has been proceeding with the reinforcement and extension of the existing jetties and the construction of breakwaters harbors and a small island within the lido inlet we detected significant local settlements of a few centimeters between march 2008 and january 2009 at the three inlets induced by the construction works through an interferometric analysis of 30 satellite radar images acquired by the new german terrasar x mission on a more regional scale we observe that the city of venice and the other major urban settlements on the lagoon littorals are not impacted by subsidence during this period the very high spatial resolution of 3 m and the short repeat time interval of 11 days of terrasar x enable the investigation of displacements with an unprecedented observed level of details opening new perspectives to geodynamic s research and civil engineering sectors for the monitoring of large infrastructures with potential vulnerability to terrain motion