high resolution particle size analysis of naturally occurring very fine grained sediment through laser diffractometry abstract in this paper we present results from a large number of experiments aimed at quantifying method and instrument uncertainty associated with laser diffraction analysis we analyzed the size distribution of fine grained sediment 24 hours prior to analysis and using 60 seconds of ultrasonication during analysis 2 obscuration a measure of the concentration of the suspension during analysis produced the most reproducible results at about 20 3 variations in refractive index settings can significantly alter estimated grain size distributions 4 assumed values for absorption the degree to which sediment grains absorb the light can have a profound effect on grain size results absorption settings near 0 resulted in unexpected bimodal grain size distributions for sediments in the 10 m size fraction and significantly skewed the fine grained tail of coarser samples probably because of sub optimal diffraction by particles with a diameter similar in size to the laser wavelength absorption settings closer to 1 produced very reproducible results and unimodal grain size distributions over a wide range of refractive indexes our study has shown that laser diffraction can measure very fine grained sediments 10 m quickly with high precision 5 at 2 standard deviations and without the need for extensive mineralogical determinations these results make possible a new generation of studies in which high resolution time series data sets of sediment grain size can be used to infer subtle changes in paleohydrology

3d multi source model of elastic volcanic ground deformation abstract developments in interferometric synthetic aperture radar insar and gnss global navigation satellite system during the past decades have promoted significant advances in geosciences providing high resolution ground deformation data with dense spatio temporal coverage this large dataset can be exploited to produce accurate assessments of the primary processes occurring in geologically active areas we present a new original methodology to carry out a multi source inversion of ground deformation data to better understand the subsurface causative processes a nonlinear approach permits the determination of location size and three dimensional configuration without any a priori assumption as to the number nature or shape of the potential sources the proposed method identifies a combination of pressure bodies and different types of dislocation sources dip slip strike slip and tensile that represent magmatic sources and other processes such as earthquakes landslides or groundwater induced subsidence through the aggregation of elemental cells this approach has the following features 1 simultaneous inversion of the deformation components and or line of sight los data 2 simultaneous determination of diverse structures such as pressure bodies or dislocation sources representing local and regional effects 3 a fully 3d context and 4 no initial hypothesis about the number geometry or types of the causative sources is necessary this methodology is applied to mt etna southern italy we analyze the ground deformation field derived from a large insar dataset acquired during the january 2009 june 2013 time period the application of the inversion approach models several interesting buried structures as well as processes related to the volcano magmatic plumbing system local subsidence within the valle del bove and seaward motion of eastern flank of the volcano

psinsar as a new tool to monitor pre eruptive volcano ground deformation validation using gps measurements on piton de la fournaise 1 the permanent scatterers synthetic aperture radar interferometry psinsar is a technique which aims at ground deformation mapping with millimetric precision in the framework of the globvolcano esa project we evaluated a psinsar derived approach to monitor ground deformation in highly active volcanic areas based on the example of piton de la fournaise the permanent scatterer ps velocities show two main areas of deformation 1 the eastern flank displaying old lava flow subsidence 0 05 0 13 m y 1 and 2 the summit cone highly disturbed by eruptions the ps time series for the summit area agree with the cgps trends with small long term weeks months ground displacements preceding eruptions 0 05 0 35 m y 1 and large rapid ground displacements linked to eruptions despite some limitations such as the loss of coherence during the most rapid ground displacements and lava flow emplacement psinsar and its derived approach provide a reliable inference of the volcano ground deformation over large areas

removal of systematic seasonal atmospheric signal from interferometric synthetic aperture radar ground deformation time series applying the multidimensional small baseline subset interferometric synthetic aperture radar algorithm to about 1500 envisat and radarsat 2 interferograms spanning 2003 2013 we computed time series of ground deformation over naples bay area in italy two active volcanoes vesuvius and campi flegrei are located in this area in close proximity to the densely populated city of naples for the first time and with remarkable clarity we observed decade long elevation dependent seasonal oscillations of the vertical displacement component with a peak to peak amplitude of up to 3 0 cm substantially larger than the long term deformation rate 0 6 cm yr analysis utilizing surface weather and radiosonde data linked observed oscillations with seasonal fluctuations of water vapor air pressure and temperature in the lower troposphere the modeled correction is in a good agreement with observed results the mean absolute and rms differences are 0 014 cm 0 073 cm and 0 087 cm respectively atmospherically corrected time series confirmed continuing subsidence at vesuvius previously observed by geodetic techniques

oblique slip on the puysegur subduction interface in the 2009 july mw 7 8 dusky sound earthquake from gps and insar observations implications for the tectonics of southwestern new zealand summary the mw 7 8 dusky sound earthquake of 2009 july 15 was the largest earthquake in new zealand in the past 80 yr and is the only major subduction interface earthquake in the new zealand historical record we have estimated the coseismic and early post seismic slip distribution in the earthquake by inversion of gps and differential interferometric synthetic aperture radar dinsar observations we show that slip during the earthquake was highly obliqueandessentiallyintheaustralia pacificrelativeplatemotiondirection failureoccurred onaca 80by50kmpatchofthesubductioninterfacewithmaximumslip5 6m inthisregion the offshore alpine fault carries up to 30 mm yr 1 of slip before terminating at resolution ridge near the southern end of the 2009 slip patch the southernmost part of the alpine fault trace lies near the up dip end of the 2009 slip patch and the fault probably exists only within the crust of the over riding plate in this region terminating at shallow depth where it meets the subduction interface there is no evidence for rupture of the alpine fault during the 2009 event however coulomb stress changes from the subduction earthquake have brought this section of the alpine fault closer to failure in contrast to many subduction zones undergoing oblique subduction where the slip in major earthquakes is partitioned into more or less pure thrustearthquakesonthesubductioninterfaceandstrike slipearthquakesinthebackarc thisis a case where the majority of the subduction interface slip is not partitioned with only a shallow convergence zone west of the strike slip alpine fault undergoing contraction approximately normal to subduction zone strike north of the 2009 earthquake region the alpine fault lies further east relative to the subduction interface and partitioning between strike slip on the alpine fault and trench normal thrusting on the subduction interface takes place in a more typical fashion our results provide the first clear demonstration of non partitioned oblique slip between the australian and pacific plates offshore of southern new zealand

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

spatiotemporal characterization of land subsidence and uplift in phoenix using insar time series and wavelet transforms the effects of land subsidence pose a significant hazard to the environment and infrastructure in the arid alluvial basins of phoenix arizona improving our understanding of the source and mechanisms of subsidence is important for planning and risk management here we employ multitemporal interferometric analysis of large synthetic aperture radar data sets acquired by ers and envisat satellites to investigate ground deformation the ers data sets from 1992 to 1996 and envisat 2003 2010 are used to generate line of sight los time series and velocities in both the ascending and descending tracks the general deformation pattern is consistent among data sets and is characterized by three zones of subsidence and a broad zone of uplift the multitrack envisat los time series of surface deformation are inverted to obtain spatiotemporal maps of the vertical and horizontal deformation fields we use observation wells to provide an in situ independent data set of hydraulic head levels then we analyze vertical interferometric synthetic aperture radar and hydraulic head level time series using continuous wavelet transform to separate periodic signal components and the long term trend the isolated signal components are used to estimate the elastic storage coefficient the inelastic skeletal storage coefficient and compaction time constants together these parameters describe the storage response of an aquifer system to changes in hydraulic head and surface elevation understanding aquifer parameters is useful for the ongoing management of groundwater resources

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

paleohydrology of china lake basin and the context of early human occupation in the northwestern mojave desert usa abstract considerable prior research has focused on the interconnected pluvial basins of owens lake and searles lake resulting in a long record of paleohydrological change in the lower owens river system however the published record is poorly resolved or contradictory for the period encompassing the terminal pleistocene 22 000 to 11 600 cal bp and early holocene 11 600 8200 cal bp this has resulted in conflicting interpretations about the timing of lacustrine high stands within the intermediate basin of china lake which harbors one of the most extensive records of early human occupation in the western great basin and california here we report a broad range of radiocarbon dated paleoenvironmental evidence including lacustrine deposits and shoreline features tufa outcrops and mollusk ostracode and fish bone assemblages as well as spring and other groundwater related deposits a k a black mats from throughout china lake basin its outlet and inflow drainages based on 98 radiocarbon dates we develop independent evidence for five significant lake level oscillations between 18 000 and 13 000 cal bp and document the persistence of groundwater fed wetlands from the beginning of the younger dryas through the early holocene 12 900 8200 cal bp including the transition from ground water fed lake to freshwater marsh between about 13 000 and 12 600 cal bp results of this study support and refine existing evidence that shows rapid high amplitude oscillations in the water balance of the owens river system during the terminal pleistocene and suggest widespread human use of china lake basin began during the younger dryas

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

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

multidimensional small baseline subset msbas for volcano monitoring in two dimensions opportunities and challenges case study piton de la fournaise volcano abstract space borne synthetic aperture radar sar provides an opportunity for monitoring ground deformation at active volcanoes with high temporal and spatial resolutions modern sar satellites acquire very large volumes of data that no longer can be effectively and efficiently processed and interpreted manually the development of novel automatic processing methodologies is warranted in order to fully utilize big data the multidimensional small baseline subset msbas methodology is an example of the semi automatic processing system for computing temporally dense two dimensional horizontal east west and vertical time series of ground deformation from ascending and descending sar imagery acquired by various satellites here msbas is used for mapping ground deformation at the piton de la fournaise volcano la reunion island france during the february 2012 april 2016 period from radarsat 2 data five volcanic eruptions occurred during the june 2014 october 2015 period producing over 60cm of horizontal and over 30cm of vertical ground deformation well resolved in the msbas derived time series validation of dinsar results by comparison with gnss observations and modeling of the two last and largest eruptions was performed validation showed good overall agreement between dinsar and gnss observations while revealing the benefits and limitations of both techniques modeling of fault and dike geometries attempted to explain the dis proportionally large eastward motion of the eastern flank of the piton de la fournaise volcano that occurred during these eruptions we demonstrated that the simple elastic model consisting of two dikes and a sliding surface can account for the observed ground deformation

principal component analysis of msbas dinsar time series from campi flegrei italy abstract because of its proximity to the city of naples and with a population of nearly 1 million people within its caldera campi flegrei is one of the highest risk volcanic areas in the world since the last major eruption in 1538 the caldera has undergone frequent episodes of ground subsidence and uplift accompanied by seismic activity that has been interpreted as the result of a stationary deeper source below the caldera that feeds shallower eruptions however the location and depth of the deeper source is not well characterized and its relationship to current activity is poorly understood recently a significant increase in the uplift rate has occurred resulting in almost 13 cm of uplift by 2013 de martino et al 2014 samsonov et al 2014b di vito et al 2016 here we apply a principal component decomposition to high resolution time series from the region produced by the advanced multidimensional sbas dinsar technique in order to better delineate both the deeper source and the recent shallow activity we analyzed both a period of substantial subsidence 1993 1999 and a second of significant uplift 2007 2013 and inverted the associated vertical surface displacement for the most likely source models results suggest that the underlying dynamics of the caldera changed in the late 1990s from one in which the primary signal arises from a shallow deflating source above a deeper expanding source to one dominated by a shallow inflating source in general the shallow source lies between 2700 and 3400 m below the caldera while the deeper source lies at 7600 m or more in depth the combination of principal component analysis with high resolution msbas time series data allows for these new insights and confirms the applicability of both to areas at risk from dynamic natural hazards

paleomagnetic secular variation and environmental magnetism of holocene age sediments from tulare lake ca abstract the lake level record from tulare lake ca has been shown to provide valuable constraints on late pleistocene and holocene runoff from the sierra nevada mountain range into the san joaquin valley of california one of the world s most prolific agricultural centers this project uses the magnetic properties of the tulare lake sediments in order to date the sediments and to constrain the relative lake level at the time of deposition shallowing lake conditions were identified leading up to a prominent unconformity magnetic mineralogy and grain size indicators primarily decreasing arm irm and s ratio values suggest coarser grain sizes and more oxidizing conditions approximately half of the samples possessed well behaved paleomagnetic directions suitable for paleomagnetic secular variation dating the results indicate that the sediments below the unconformity were deposited approximately 7600 8500 cal yr bp and the sediments above the unconformity were deposited approximately 2500 800 cal yr bp the ages of the corresponding sediments are consistent with the time intervals during which previous studies indicate that lake level was above the elevation of this site before and after a mid holocene regression

monitoring the fate of injected co2 using geodetic techniques author s vasco dw dixon th ferretti a samsonov sv abstract 2020 by the society of exploration geophysicists geodetic methods comprise one class of geophysical data that are sensitive to changes in effective pressure within operating reservoirs albeit indirectly through induced deformation geodetic observations which have observation intervals that vary from seconds to days weeks or months generally provide more frequent sampling compared to existing geophysical methodologies such as seismic time lapse monitoring which typically invoke repeat times of months to years these differences in sampling intervals are primarily due to the extensive effort and hence cost of conducting geophysical field operations which often precludes executing a large number of surveys satellite based interferometric synthetic aperture radar insar is cost effective and used in many applications including monitoring the injection of carbon dioxide co2 for both long term storage and enhanced oil production an application to the geologic sequestration of co2 in algeria revealed northwest migration along a fault fracture zone intersected by the injection well a study in a texas field demonstrated that enhanced oil recovery utilizing co2 leads to observable surface deformation that may be used to characterize the sequestered co2 and to estimate the pressure changes within the reservoir induced by injection and production

millennial climate oscillations in ne pacific surface waters over the last 82 kyr new evidence from alkenones 1 a climate instability in the last glacial corresponding to dansgaard oeschger d o events has been already recognized in the california margin in northeast pacific detailed sea surface temperature sst changes in this region however have not been so far well elucidated here we report estimates of alkenone derived ssts with the do time scale from odp hole 1017e off point conception over the last 80 kyr our results show that alkenone ssts clearly record d o and heinrich events we also found that alkenone ssts during 82 58 ka and 18 15 ka were considerably higher and those in 15 12 ka were lower than those derived from 18o of planktonic foraminifera these results appear to reflect fluctuations of water masses

nyamulagira s magma plumbing system inferred from 15 years of insar nyamulagira located in the east of the democratic republic of congo on the western branch of the east african rift is africa s most active volcano with an average of one eruption every 3 years since 1938 owing to the socio economical context of that region the volcano lacks ground based geodetic measurements but has been monitored by interferometric synthetic aperture radar insar since 1996 a combination of 3d mixed boundary element method and inverse modelling taking into account topography and source interactions is used to interpret insar ground displacements associated with eruptive activity in 1996 2002 2004 2006 and 2010 these eruptions can be fitted by models incorporating dyke intrusions and some namely the 2006 and 2010 eruptions require a magma reservoir beneath the summit caldera we investigate inter eruptive deformation with a multi temporal insar approach we propose the following magma plumbing system at nyamulagira by integrating numerical deformation models with other available data a deep reservoir c 25 km depth feeds a shallower reservoir c 4 km depth proximal eruptions are fed from the shallow reservoir through dykes while distal eruptions can be fed directly from the deep reservoir a dyke like conduit is also present beneath the upper southeastern flank of nyamulagira

an organic geochemical record of sierra nevada climate since the lgm from swamp lake yosemite abstract sediment records from swamp lake sl in the central sierra nevada california provide evidence of climatic change on millennial and centennial timescales over the last 20 000 years total organic carbon toc abundance varied in concert with elemental and isotopic tracers of organic matter c n 13 c org 15 n biogenic silica content total magnetic susceptibility and sediment lithology we interpret the down core proxy records as representing the response of the lake environment in terms of temperature seasonal ice cover mixing regimes runoff and in situ om and nutrient cycling to shifting climate states these environmental factors in turn drove changes in algal productivity om sources microbial om regeneration and secondary production and detrital input the late pleistocene 19 7 10 8 cal kyr bp was dominated by fluctuations between relatively warm dry intervals with high toc 17 4 16 5 15 8 15 0 13 9 13 2 11 4 11 0 cal kyr bp and cold wet intervals 16 5 15 8 14 8 13 9 13 1 11 6 11 0 10 7 cal kyr bp characterized by low toc and high detrital input the holocene 10 7 cal kyr bp present was characterized by three abrupt increases in toc after 10 8 8 0 and 3 0 cal kyr bp and numerous century scale fluctuations toc increases reflected enhanced lake productivity and om recycling and reduced detrital input in response to changing winter temperature and hydrologic regimes inferred environmental changes at sl correlate with other sierra nevada paleorecords and with reconstructed sea surface temperatures along the california margin parallel changes in the sl and sst records over the past 20 000 years provide new evidence that continental climate in the sierra nevada and the california current system have responded on multiple timescales to common drivers in north pacific ocean atmospheric circulation

latest pleistocene to holocene hydroclimates from lake elsinore california abstract the hydroclimate of the southwestern united states us region changed abruptly during the latest pleistocene as the continental ice sheets over north america retreated from their most southerly extent to investigate the nature of this change we present a new record from lake elsinore located 36 km inland from the pacific ocean in southern california and evaluate it in the context of records across the coastal and interior southwest united states including northwest mexico the sediment core recovered from lake elsinore provides a continuous sequence with multi decadal resolution spanning 19 9 ka bp sedimentological and geochemical analyses reveal hydrologic variability in particular sand and carbonate components indicate abrupt changes at the oldest dryas od bolling allerod ba and younger dryas yd transitions consistent with the timing in greenland hydrogen isotope analyses of the c28 n alkanoic acids from plant leaf waxes dwax reveal a long term trend toward less negative values across 19 9 ka bp dwax values during the od suggest a north pacific moisture source for precipitation consistent with the dipping westerlies hypothesis we find no isotopic evidence for the north american monsoon reaching as far west as lake elsinore therefore we infer that wet dry changes in the coastal southwest were expressed through winter season precipitation consistent with modern climatology comparing lake elsinore to other southwest records notably cave of bells and fort stanton we find coincident timing of the major transitions od to ba ba to yd and hydrologic responses during the od and ba the hydrologic response however varied during the yd consistent with a dipole between the coastal and interior southwest the coherent pattern of hydrologic responses across the interior southwest us and northwest mexico during the od wet the ba drier and yd wet follows changes in the atlantic meridional overturning circulation presumably via its combined influence on north pacific winter storm tracks and the extent magnitude of the north american monsoon in contrast lake elsinore and the coastal southwest experiences a deglacial drying trend punctuated by abrupt change at the od to ba and ba to yd transitions this trend tracks rising greenhouse gases through the deglacial with an apparent southward shift in westerly moisture sources adjusting to the retreating ice sheet

geodetic imaging of time dependent three component surface deformation application to tidal timescale ice flow of rutford ice stream west antarctica we present a method for inferring time dependent three component surface deformation fields given a set of geodetic images of displacements collected from multiple viewing geometries displacements are parameterized in time with a dictionary of displacement functions the algorithm extends an earlier single component i e single line of sight framework for time series analysis to three spatial dimensions using combinations of multitemporal multigeometry interferometic synthetic aperture radar insar and or pixel offset po maps we demonstrate this method with a set of 101 pairs of azimuth and range po maps generated for a portion of the rutford ice stream west antarctica derived from data collected by the cosmo skymed satellite constellation we compare our results with previously published insar mean velocity fields and selected gps time series and show that our resulting three component surface displacements resolve both secular motion and tidal variability

a fan dam for tulare lake california and implications for the wisconsin glacial history of the sierra nevada historic fluctuations and late quaternary deposits of tulare lake in the southern san joaquin valley indicate that maximum lake size has depended chiefly on the height of a frequently overtopped spillway this dependence gives tulare lake a double record of paleoclimate climate in the tulare lake region has influenced the degree to which the lake fills its basin during dry seasons and dry years during the past 100 000 130 000 yr incidence of desiccation of tulare lake inferred from stiffness mud cracks and other hand specimen properties has been broadly consistent with the lake9s salinity and depth inferred from diatoms and ostracodes and with regional vegetation inferred from pollen climate however also appears to control basin capacity itself tulare lake becomes large as a consequence of glacial outwash aggradation of its alluvial fan dam late wisconsin enlargement of tulare lake probably resulted from the last major glaciation of the sierra nevada the lake9s spillway coincides with the axis of the glacial outwash fan of a major sierra nevada stream moreover sediment deposited in the transgressive lake resembles glacial rock flour from the sierra nevada differential tectonic subsidence and deposition by a coast range creek facilitated the building of tulare lake9s fan dam during the late wisconsin but were less important than deposition of sierra nevada outwash four stratigraphically consistent 14 c dates on peat and wood give an age of 26 000 yr b p for the start of tulare lake9s late wisconsin transgression the last major sierra nevada glaciation tioga glaciation thus may have begun about 26 000 yr b p provided that vigorous glacial outwash deposition began early in the glaciation onset of the tioga glaciation about 26 000 yr b p is consistent with new stratigraphic and radiocarbon data from the northeastern san joaquin valley these data suggest that the principal episode of glacial outwash deposition of wisconsin age began in the san joaquin valley after 32 000 yr b p rather than at least 40 000 yr b p as previously believed an earlier enlargement of tulare lake probably resulted from a fan dam produced by the penultimate major tahoe glaciation of the sierra nevada average sedimentation rates inferred from depths to a 600 000 yr old clay and from radiocarbon dates indicate that this earlier lake originated no later than 100 000 yr b p the tahoe glaciation therefore is probably pre wisconsin

implications of a freshwater radiocarbon reservoir correction for the timing of late holocene settlement of the elk hills kern county california abstract uncertainties regarding the magnitude of freshwater radiocarbon reservoir effects can introduce random errors into dates on archaeological freshwater carbonates as a result many archaeologists avoid dating freshwater shells unless no other datable materials are available the chronology of prehistoric occupation of the former naval petroleum reserve no 1 npr 1 at elk hills kern county has been established with 50 radiocarbon dates on freshwater mussels gonidea and anodonta sp characterization of any freshwater radiocarbon reservoir effect is crucial for the accurate interpretation of inferred settlement and subsistence changes on the elk hills paired charcoal and freshwater mussels sampled from closely associated contexts were dated to identify a freshwater reservoir effect paired anodonta and gonidea sp shells were dated to investigate interspecific differences in fractionation results indicate that a 340 20 14 c yr correction should be applied to conventional 14 c dates on freshwater carbonates in the buena vista basin before calendar calibration evidence of interspecific differences is inconclusive dates recalibrated with the reservoir correction indicate that widespread occupation of the elk hills is correlated with increasing precipitation towards the end of the medieval climatic anomaly and during the little ice age suggesting that slough resource exploitation may have been driven by regional population pressure rather than drought related declines in aquatic productivity

rapidly accelerating subsidence in the greater vancouver region from two decades of ers envisat radarsat 2 dinsar measurements abstract rapidly accelerating ground subsidence in the south western part of british columbia the third largest metropolitan area in canada with over 2 3 million of inhabitants is estimated using the multidimensional small baseline subset msbas advanced differential interferometric synthetic aperture radar dinsar an effective processing strategy for multi mission multi temporal sar data the synthetic aperture radar sar data used in this study consists of seven independent data sets one ascending and one descending ers 1 2 and envisat frames together spanning july 1995 september 2010 and three radarsat 2 frames spanning february 2009 october 2012 during the july 1995 october 2012 period we observe fast ground subsidence with a maximum rate of about 2 cm year in the greater vancouver region that includes the fraser river delta and the cities of burnaby richmond surrey new westminster and vancouver the rapidly accelerating subsidence is observed beneath the vancouver international airport skytrain terminal as well as several agricultural and industrial locales these time series suggest that the subsidence rate at the studied regions does not decrease with time as suggested in previous studies but remains steady or increases these results also demonstrate the importance of acquiring and appropriately estimating longer time series as previous studies on the same greater vancouver area may have misinterpreted the long term ground deformation rate and direction and underestimated the potential hazard the long term impact of this subsidence on urban infrastructure can be significant and needs to be investigated further

short and long term ground deformation due to cyclic steam stimulation in alberta canada measured with interferometric radar short and long term ground deformation at the cyclic steam stimulation css enhanced oil recovery sites in the cold lake region of alberta canada was measured with radarsat 2 differential interferometric synthetic aperture radar dinsar during 2011 2016 the interferometric processing of 84 high resolution spotlight images revealed extensive short term ground uplift and subsidence greater than 15 cm over the 24 day satellite revisit cycle time series analysis based on the multidimensional small baseline subset msbas methodology demonstrated that while the predominant deformation signal is cyclical in nature a long term subsidence and uplift with maximum deformation rates greater than 5 cm year is also present these measurements suggest that css injection and production operations result in the long term semipermanent deformation in the area of reservoir operations and that the response to injection and extraction can differ from the previous cycles

subsidence at cerro prieto geothermal field and postseismic slip along the indiviso fault from 2011 to 2016 radarsat 2 dinsar time series analysis we present radarsat 2 differential interferometric synthetic aperture radar dinsar observations of deformation due to fluid extraction at the cerro prieto geothermal field cpgf and afterslip on the 2010 m7 2 el mayor cucapah emc earthquake rupture during 2011 2016 advanced multidimensional time series analysis reveals subsidence at the cpgf with the maximum rate greater than 100 mm yr accompanied by horizontal motion radial contraction at a rate greater than 30 mm yr during the same time period more than 30 mm of surface creep occurred on the indiviso fault ruptured by the emc earthquake we performed inversions of dinsar data to estimate the rate of volume changes at depth due to the geothermal production at the cpgf and the distribution of afterslip on the indiviso fault the maximum coseismic slip due to the emc earthquake correlates with the coulomb stress changes on the indiviso fault due to fluid extraction at the cpgf afterslip occurs on the periphery of maximum coseismic slip areas time series analysis indicates that afterslip still occurs 6 years after the earthquake

interferometric synthetic aperture radar study of okmok volcano alaska 1992 2003 magma supply dynamics and postemplacement lava flow deformation 1 okmok volcano located in the central aleutian arc alaska is a dominantly basaltic complex topped with a 10 km wide caldera that formed circa 2 05 ka okmok erupted several times during the 20th century most recently in 1997 eruptions in 1945 1958 and 1997 produced lava flows within the caldera we used 80 interferometric synthetic aperture radar insar images interferograms to study transient deformation of the volcano before during and after the 1997 eruption point source models suggest that a magma reservoir at a depth of 3 2 km below sea level located beneath the center of the caldera and about 5 km northeast of the 1997 vent is responsible for observed volcano wide deformation the preeruption uplift rate decreased from about 10 cm yr 1 during 1992 1993 to 2 3 cm yr 1 during 1993 1995 and then to about 1 2 cm yr 1 during 1995 1996 the posteruption inflation rate generally decreased with time during 1997 2001 but increased significantly during 2001 2003 by the summer of 2003 30 60 of the magma volume lost from the reservoir in the 1997 eruption had been replenished interferograms for periods before the 1997 eruption indicate consistent subsidence of the surface of the 1958 lava flows most likely due to thermal contraction interferograms for periods after the eruption suggest at least four distinct deformation processes 1 volcano wide inflation due to replenishment of the shallow magma reservoir 2 subsidence of the 1997 lava flows most likely due to thermal contraction 3 deformation of the 1958 lava flows due to loading by the 1997 flows and 4 continuing subsidence of 1958 lava flows buried beneath 1997 flows our results provide insights into the postemplacement behavior of lava flows and have cautionary implications for the interpretation of inflation patterns at active volcanoes

the rambla highstand shoreline and the holocene lake level history of tulare lake california usa abstract the stratigraphy associated with a highstand wave cut shoreline and with sites farther out into the lake plain constrain the holocene lake level history of tulare lake california usa as follows seven to eight major fluctuations in lake level occurred during the past 11 500 yr lake level was generally higher during the early holocene prior to 6000 cal yr bp peaking in two highstands 65 70 masl at 9500 8000 cal yr bp and 6900 5800 cal yr bp thereafter it fluctuated at lower amplitude until reaching a major highstand during the most recent millennium between 750 and 150 cal yr bp two lake level rises of lower amplitude were centered on 3300 and 1600 cal yr bp at least three probably brief lowstands

a 9170 year record of decadal to multi centennial scale pluvial episodes from the coastal southwest united states a role for atmospheric rivers abstract a well dated 9170 calendar year before present cal yr bp paleohydrologic reconstruction is presented from lower bear lake in the san bernardino mountains of the coastal southwest united states this new multi proxy record is characterized by alternating organic rich carbonate rich sediment units interpreted to reflect hydrologically forced changes in the lake s depositional environment our interpretation of the proxy data indicates nine decadal to multi centennial pluvial episodes pe over the past 9170 cal yr bp of these nine inferred pluvials five are interpreted as more pronounced based on their combined proxy interpretations pe v 9170 8250 pe iv 7000 6400 pe iii 3350 3000 pe ii 850 700 and pe i 500 476 top of core cal yr bp the lower bear lake record indicates that the san bernardino mountains source region for the mojave river and its terminal playa was wet during the same periods within dating errors to several of the major pluvials proposed from the lakes in the sink of the mojave river our comparison extends north also to tulare lake which drains the southcentral western sierra nevada mountains this temporally and spatially coherent signal indicates that a similar climate forcing acted to increase regional wetness at various times during the past 9170 cal yr bp as originally proposed by enzel ely and colleagues e g enzel et al 1989 enzel 1992 ely et al 1994 enzel and wells 1997 we too contend that holocene pluvial episodes are associated with changing the frequency of large winter storms that track across a broad region at decadal to multi centennial timescales we build upon their hypothesis through the addition of new and better dated site comparisons recent advances in the understanding of atmospheric rivers and improved knowledge of the ocean atmosphere dynamics that caused the early 20th century western united states pluvial

a seamless multitrack multitemporal insar algorithm the zones of overlap between adjacent synthetic aperture radar sar satellite tracks are illuminated twice more frequently than elsewhere in the sar scene here an alternative approach is presented to combine the overlapping segments of sar images acquired at adjacent tracks and generate accurate and high spatiotemporal resolution map of the surface deformation field to this end a new approach is developed to unify the datums effects due to the difference in look angle between two overlapping tracks and atmospheric delay are estimated and removed using kalman and wavelet based filters this approach is first tested at hawaii island where tracks 200 and 429 of envisat c band satellite overlap over the kilauea south flank the obtained time series improves the temporal sampling rate by a factor of two and comparison with gps time series demonstrates that the presented method accurately measures the nonlinear deformation field the advantages of this method are further demonstrated by combining sar data sets acquired by envisat c band and alos l band satellites over the san francisco bay area california the validation test shows that the seamless combination of c band and l band time series accurately measures the surface deformation at higher resolution

geodetic constraints of the 2017 m w 7 3 sarpol zahab iran earthquake and its implications on the structure and mechanics of the northwest zagros thrust fold belt

triggered slip observations of the 17 august 1999 izmit turkey earthquake using radar interferometry we use synthetic aperture radar interferometry insar to map the displacement field of the 17 august 1999 izmit earthquake which largely conforms to that predicted for an elastic upper crust we determine the earthquake source parameters and show that slip continues farther west than the mapped fault ruptures we also show that additional sub surface displacements occurred on parallel strands of the north anatolian fault zone we argue that this was caused by changes in static stress accompanying the mainshock or by the dynamic release of regional stresses

volcano geodesy recent developments and future challenges abstract ascent of magma through earth s crust is normally associated with among other effects ground deformation and gravity changes geodesy is thus a valuable tool for monitoring and hazards assessment during volcanic unrest and it provides valuable data for exploring the geometry and volume of magma plumbing systems recent decades have seen an explosion in the quality and quantity of volcano geodetic data new datasets some made possible by regional and global scientific initiatives as well as new analysis methods and modeling practices have resulted in important changes to our understanding of the geodetic characteristics of active volcanism and magmatic processes from the scale of individual eruptive vents to global compilations of volcano deformation here we describe some of the recent developments in volcano geodesy both in terms of data and interpretive tools and discuss the role of international initiatives in meeting future challenges for the field

satellite interferometry for mapping surface deformation time series in one two and three dimensions a new method illustrated on a slow moving landslide abstract space borne differential interferometric synthetic aperture radar dinsar has been extensively used in the last two decades to measure ground surface deformation providing key information for the characterization and understanding of many natural and anthropogenic processes however conventional dinsar technique measures only one component of the surface deformation i e the satellite s line of sight los causing the interpretation of dinsar measurements to be challenging and potentially narrowing the understanding of the mechanisms and dynamics of the deformation processes at work presently available methods that estimate 3d surface deformation from dinsar generally operate on individual interferograms and therefore do not produce 3d surface deformation time series however the availability of time series is essential for studying surface deformation processes bringing information on e g temporally and spatially variable external forcing conditions and characteristics of future deformation patterns the multidimensional small baseline subset msbas method was already able to produce 2d east and vertical surface deformation time series from multi tracks and multi sensors dinsar data here we propose a novel version of the msbas msbas 3d method that can produce 3d north east and vertical surface deformation time series from ascending and descending dinsar data this new method proposes measuring the surface deformation for processes producing motion parallel to the surface such as landslides and glacier flows while conserving the dinsar accuracy the ability of msbas 3d to capture the full 3d deformation pattern of processes with a surface signature is illustrated for a large slow moving deep seated landslide for which long dinsar and dgnss time series as well as ground truth data are available surface deformation is measured over a four year period using 1d los 2d and 3d msbas methods and the advantages and limitations of each approach are described in this case the novel msbas 3d technique produces superior results that greatly simplify interpretation of the processes at work the msbas 3d software can be downloaded from http insar ca

post emplacement dynamics of andesitic lava flows at volcan de colima mexico revealed by radar and optical remote sensing data abstract we used optical and radar remote sensing datasets to map estimate the volume and measure the surface displacements of lava flows emplaced on the flanks of volcan de colima mexico by extrusion of lava dome material from the end of 2014 to early 2016 our main result is that the flow motion of the lava contributes significantly to the recorded displacements several months after its emplacement first we mapped the deposits and estimated their volumes using two digital elevation models dem one derived from radar data acquired before the peak of activity and one derived from optical images acquired just after this peak of activity coherence information derived from the radar dataset added some temporal constraints on the timing of emplacement of various deposits we thus estimated a mean extrusion rate of 1 2 m3 s 1 between november 2014 and february 2015 we then used a new approach to reconstruct the 3d displacement field taking advantage of images acquired by the same satellite on both ascending and descending tracks and using a physical a priori on the direction of horizontal displacements our results show that about 2 cm yr 1 of horizontal motion is still recorded a few months after the emplacement on the sw lava flow which is the only one covered by the two acquisition geometries in order to differentiate the potential causes of the observed displacements we modeled the thermal contraction of the lava flow using a finite element numerical method removing the contribution of thermoelastic contraction from the measured displacements enable to infer both the viscoelastic loading and flow motion effects from the residuals results show that thermal contraction flow motion and viscoelastic loading contribute significantly to the displacements recorded

spatiotemporal analysis and interpretation of 1993 2013 ground deformation at campi flegrei italy observed by advanced dinsar campi flegrei is one of the most hazardous volcanic areas in the world because of its close proximity to the city of naples here we apply the multidimensional small baseline subset msbas differential interferometric synthetic aperture radar dinsar technique to obtain vertical and horizontal components of ground deformation for campi flegrei at high spatial and temporal resolutions that span for the first time 20 years the area underwent continuous subsidence from 1993 through 1999 moderate uplift began in 2010 and substantially increased through 2012 reaching approximately 13 cm by 2013 we model the observed deformation to determine source parameters for subsidence and uplift epochs both the inflation and deflation mechanisms involve large extended sources in a layered hydrothermal system whose location is controlled by the caldera structure and stratigraphy the temporal resolution of msbas approaches that of gps daily time series with superior precision and spatial resolution making it an excellent alternative for volcano monitoring

a late pleistocene holocene noble gas paleotemperature record in southern michigan 1 noble gas temperatures ngts and 14c derived ages in groundwaters of the michigan basin reveal a ground temperature of 1 c toward the end of the last glacial maximum lgm suggesting that groundwater recharge occurred under the laurentide ice sheet lis cover in addition to the general warming observed since the lgm the ngt record indicates an abrupt warming event between 12 8 and 11 1kyrs bp correlative to the bolling allerod boa warm phases ice sheet linked changes in freshwater delivery to the north atlantic together with changes in the north atlantic deep water nadw circulation are possible causes of such abrupt climate shifts in northeastern us pleistocene waters yielding the lowest ngts have the highest 18o and d values suggesting an atmospheric circulation pattern distinct from today with a stronger moisture component from the gulf of mexico possibly due to the presence of the lis which weakened the pacific westerly flow

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

lake levels for the past 19 000 years from the tl05 4 cores tulare lake california usa geophysical and geochemical proxies abstract geochemical and geophysical proxy data from the tl05 4 lake plain cores of tulare lake california are reported on here representing most of the past 19 000 years the new record consists of carbon nitrogen ratios total organic carbon toc nitrogen n total inorganic carbon tic grain size and magnetic susceptibility analyses from samples taken at 1 cm intervals 45 yr sample age control is provided by 22 radiocarbon dates the first part of the record 19 0 14 5 cal ka bp consists of elevated sand and silt percentages and higher sedimentation rates interpreted as elevated runoff associated with melting of the tioga age sierra nevada ice cap the tic was undetectable and toc and n were low suggesting low productivity in a relatively sterile freshwater lake from 14 5 to 10 3 cal ka bp the deposits consisted of 50 clay and 50 silt with tic and toc extremely low which is consistent with a stable low productivity lake from 10 3 to 7 5 cal ka bp an initial pulse of fining upward sand gave way to increased clay deposition that suggests a lake transgression to a stable highstand coeval with the deep water event found in previously published records of tulare lake and other lakes from central and southern california including owens lake and lake elsinore a few hundred year duration spikes in tic centered at 8 0 cal ka bp is suggestive of evaporating lake conditions toward the end of this early holocene highstand tulare lake dropped quickly to a relative low at 7 5 cal ka bp but then lake level increased steadily until 3 0 cal ka bp high amplitude fluctuation in almost all proxies occurs from 2 5 to 1 8 cal ka bp at the end of the record suggesting that this time interval was characterized by rapid fluctuations in lake level tulare lake levels during the holocene vary in conjunction with sea surface temperature sst records from the ocean drilling program odp site 1017 located off the coast of central california which suggests that variations in ssts throughout the holocene drove changes in precipitation in the sierra nevada and hence tulare lake level since historic lake level histories have been shown to be directly related to stream discharge from the sierra nevada this observation will be integral in forecasting future decadal scale changes in southern san joaquin valley water supply due to anticipated climate change

last glacial maximum and holocene lake levels of owens lake eastern california usa abstract stratigraphic investigations of fluvio deltaic and lacustrine sediments exposed in stream cuts quarry walls and deep trenches east of the sierra nevada in owens valley near lone pine california have enabled the reconstruction of pluvial owens lake level oscillations age control for these sediments is from 22 radiocarbon 14 c dates and the identification and stratigraphic correlation of a tephra which when plotted as a function of age versus altitude define numerous oscillations in the level of pluvial owens lake during the latest pleistocene and early holocene we have constructed a lake level altitude curve for the time interval 27 000 cal yr bp to present that is based on the integration of this new stratigraphic analysis with published surface stratigraphic data and subsurface core data pluvial owens lake regressed from its latest pleistocene highstands from 27 000 to 15 300 cal yr bp as recorded by 15 m of down cutting of the sill from the altitudes of 1160 to 1145 m by 11 600 cal yr bp the lake had dropped 45 m from the 1145 m sill this lowstand was followed by an early holocene transgression that attained a highstand near 1135 m before dropping to 1120 m at 7860 7650 cal yr bp that had not been recognized in earlier studies the lake then lowered another 30 m to shallow and near desiccation levels between 6850 and 4300 cal yr bp fluvial cut and fill relations north of lone pine and well preserved shoreline features at 1108 m indicate a minor lake level rise after 4300 cal yr bp followed by alkaline and shallow conditions during the latest holocene the new latest quaternary lake level record of pluvial owens lake offers insight to the hydrologic balance along the east side of the southern sierra nevada and will assist regional paleoclimatic models for the western basin and range

geoarchaeological and paleohydrological evidence for a clovis age drought in north america and its bearing on extinction abstract at the murray springs clovis site in southeastern arizona stratigraphic and geomorphic evidence indicates that an abnormally low water table 10 900 yr b p was followed soon thereafter by a water table rise accompanied by the deposition of an algal mat the black mat that buried mammoth tracks clovis artifacts and a well this water table fluctuation correlates with pluvial lake fluctuations in the great basin during and immediately following clovis occupation of that region many elements of pleistocene megafauna in north america became extinct during the dry period oxygen isotope records show a marked decrease in 18o correlated with the younger dryas cold dry event of northern europe which ended 10 750 yr b p essentially the same time as the water table began to rise in southeastern arizona clovis hunters may have found large game animals easier prey when concentrated at water holes and under stress if so both climate and human predation contributed to pleistocene extinction in america

multi temporal sar observations of the surat basin in australia for deformation scenario evaluation associated with man made interactions human activities for extracting natural resources may lead to subsequent gradual or abrupt surface deformation with adverse effects in the local ecosystem and damage to man made structures over the past two decades interferometric sar insar has been demonstrated as the optimal remote sensing technique to estimate surface deformation with high spatial coverage and vertical accuracy over traditional surveying methods in this paper the outcome of advanced differential insar processing to detect and analyze ground surface behavior due to man made interactions are presented an improvement was achieved in the temporal resolution and accuracy using a unique combination of both c band and l band sar satellite acquisitions with different temporal and spatial baselines the two alternate dinsar methodologies were applied on the northeastern part of the surat basin australia for an area without long term ground based geodetic observations the regions undergoing downward motion are located above coal seam gas csg mining sites with rates up to 28 mm year three scenarios were identified 1 extensive groundwater extraction from shallow aquifers due to csg mining 2 csg mining without direct impact on groundwater resources and 3 patchy uplift over an industrial forest adjacent to a csg mining district contrary to a previous study conducted in this region using the psinsar technique which reported stability of the area with insignificant surface deformation this study shows that there are considerable deformation signals consistent with resource extraction consequently it is shown that the sbas approach is superior to psinsar for deformation monitoring with focusing on naturally distributed scatterers

ground deformation in the taupo volcanic zone new zealand observed by alos palsar interferometry summary we present ground deformation measurements in the taupo volcanic zone tvz using differential interferomeric synthetic aperture radar dinsar observations collected by alos palsar during 2006 2010 and compare them with displacement observations from continuous gps we acquired and processed dinsar images from two ascending paths 324 and 325 and one descending path 628 covering the tvz and produced linear deformation rates and time series of deformation the dinsar results were improved by using a modified version of the small baseline subset sbas algorithm that simultaneously solves for deformation rates and residual topographic noise the accuracy of the dinsar displacement rates along line of sight to the satellite is 0 5 2 cmyr 1 depending on the number of sar images and their coherence we found good agreement between the dinsar derived displacement rates and those measured by continuous gps for the two ascending paths correlation 0 94 0 01 and 0 89 0 02 the dinsar uncertainties were too large to make a useful comparison for the descending path correlation 0 66 0 03 we identified ground deformation due to groundwater and steam extraction for geothermal power to demonstrate the geophysical application we modelled the deformation results using simplified sources for some of the geothermal signals using ellipsoidal and tabular approximations

detailed multidisciplinary monitoring reveals pre and co eruptive signals at nyamulagira volcano north kivu democratic republic of congo this paper presents a thorough description of nyamulagira s january 2010 volcanic eruption north kivu democratic republic of congo based on a combination of field observation and ground based and space borne data it is the first eruption in the virunga volcanic province that has been described by a combination of several modern monitoring techniques the 2010 eruption lasted 26 days and emitted 45 5 106 m3 of lava field observations divided the event into four eruptive stages delimited by major changes in effusive activity these stages are consistent with those described by pouclet 1976 for historical eruptions of nyamulagira co eruptive signals from ground deformation seismicity so2 emission and thermal flux correlate with the eruptive stages unambiguous pre eruptive ground deformation was observed 3 weeks before the lava outburst coinciding with a small but clear increase in the short period seismicity and so2 emission the 3 weeks of precursors contrasts with the only precursory signal previously recognized in the virunga volcanic province the short term increase of tremor and long period seismicity which for example were only detected less than 2 h prior to the 2010 eruption the present paper is the most detailed picture of a typical flank eruption of this volcano it provides valuable tools for re examining former mostly qualitative descriptions of historical nyamulagira eruptions that occurred during the colonial period

magma flux at okmok volcano alaska from a joint inversion of continuous gps campaign gps and interferometric synthetic aperture radar 1 volcano deformation is usually measured using satellite geodetic techniques including interferometric synthetic aperture radar insar campaign gps and continuous gps differences in the spatial and temporal sampling of each system mean that most appropriate inversion scheme to determine the source parameters from each data set is different most studies either compare results from independent inversions or subsample the data sets to the lowest common factor it is unclear whether differences in the solution reflect differences in source behavior differences in measurement bias or differences in inversion technique here we develop a single inversion procedure that captures the benefits of each system especially the daily sampling of continuous gps and the high spatial resolution of insar okmok volcano alaska is an ideal target for such a test because a long series 15 years of insar and continuous gps measurement exists and the source is almost continuously active and in a stable location

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

quantifying groundwater exploitation induced subsidence in the rafsanjan plain southeastern iran using insar time series and in situ measurements abstract decades of groundwater overexploitation for agriculture and industrial development have resulted in substantial land subsidence in the rafsanjan plain of southeastern iran this work presents the results of an insar time series analysis obtained by the exploitation of envisat alos and sentinel 1 s1 sar data archives between june 2004 and may 2016 to investigate land subsidence in the plain the insar analysis revealed an area of approximately 1000 km 2 within the study area showing subsidence of 5 cm year and locally exceeding 30 cm yr in the last decade this area of significant subsidence is limited in its spatial extent to the agricultural land and is partly influenced by quaternary faults the temporal and areal relationships of subsidence and groundwater level data suggest that a significant part of the observed subsidence in the rafsanjan region is caused by intense groundwater extraction that has led to widespread compaction within the upper parts of the up to 300 m thick unconsolidated sediments causing irreversible and inelastic deformation of the aquifer the average volume storage loss of the aquifer system due to overexploitation is estimated to have been approximately 300 million cubic metre mcm yr over the last decade

late holocene climate change inferred from a lacustrine sedimentary sequence in southern inner mongolia china abstract this study presents a series of paleoenvironmental results from a radiocarbon dated 154 cm long lacustrine sedimentary sequence from qrdin nuur 115 51 20 e 42 36 20 06 n elevation 1290 asl in southern inner mongolia china measurements of grain size magnetic susceptibility ms total nitrogen tn total organic carbon toc total inorganic carbon tic atomic toc tn c n and carbonate content were conducted in order to reconstruct the climate since 3700 cal a bp in addition to a regional drying trend in the late holocene closely related to the weakening of the east asian summer monsoon easm four distinct climatic stages can be identified i from 3700 to 2909 cal a bp a semi arid and cool climate dominated the lake area with a transitory climatic amelioration from 3300 to 3150 cal a bp ii the interval from 2909 to 2589 cal a bp was characterized by a rising temperature and the recovery from drought iii from 2589 to 1903 cal a bp drought conditions were renewed and significantly intensified in a cold environment iv after 1903 cal a bp a warm climate with severe evaporation accelerated the shrinking of qrdin nuur a comparison of our results with other paleoclimatic records mainly from southern inner mongolia reveals similar climatic trends and highlights the asynchronous nature of the regional climatic transition to increased aridity which was reflected by the activation of the otindag sandy land and by the dominance of steppe landscapes several multi centennial temperature oscillations are recognized over the last two millennia as inferred from fluctuations in tic and carbonate content we correlate the warm interval from 853 to 560 cal a bp 1097 1390 ad with the medieval warm period mwp and the consequent cold interval from 560 to 128 cal a bp 1390 1822 ad with the little ice age lia furthermore the climatic reconstruction shows that the lake area was generally drier during the lia than in the mwp

drought driven transient aquifer compaction imaged using multitemporal satellite radar interferometry in unconsolidated heterogeneous aquifer systems low rates of pore pressure diffusion of applied effective stresses due to the drainage of thick low permeability clay rich layers with time constants of decades to centuries cause delayed residual permanent compaction and land subsidence current application of satellite differential radar interferometry dinsar differential interferometric synthetic aperture radar to estimate aquifer hydraulic properties compressibility and or storage in these systems is limited by the temporal availability of synthetic aperture radar data 1992 present in this paper we study the degree of aquifer compaction due to water extraction using dinsar through an example in southeast spain ground deformation data indicate large scale deformation and in particular the discovery of the highest rates of groundwater related land subsidence recorded in europe 10 cm yr affecting the guadalentin river basin 200 km 2 the largest tributary of the segura river modeling of the ground surface time series of the guadalentin basin indicates that deformation is mainly driven by nonlinear time delayed flow processes in the underlying aquifer after a drought period 1990 1995 the aquifer responded with an exponential decay of the land subsidence lasting 8 yr suggesting transient groundwater pore pressure flow we show that multitemporal satellite radar interferometry analysis and its modeling can be a stimulating way to study nonlinear soil mechanics and groundwater flows at aquifers a deeper understanding of such processes could help the management of water resources and land subsidence of unconsolidated coastal and quaternary alluvial aquifers in a highly evolving climate region the mediterranean sea and elsewhere

extreme southwestern margin of late quaternary glaciation in north america timing and controls well preserved latero frontal moraines in the eastern san bernardino mountains of southern california provide evidence for several glacial advances during the late quaternary and mark the southwesternmost limit of glaciation in the western cordillera using geomorphology and 10be cosmogenic radionuclide dating a succession of moraines from three glaciated valleys is dated to 18 20 ka last glacial maximum 15 16 ka heinrich event 1 12 13 ka younger dryas stade and 5 9 ka early middle holocene these ages substantiate the view that glaciation throughout the american cordilleras was synchronous during the late quaternary furthermore these data show that glacial advances in southern california occur when a significant decrease in summer temperature is coupled with an increase in moisture flux producing high winter snowfall this allows for perennial snow accumulation that may under appropriate conditions persist to form glacial ice

pluvial lakes in the great basin of the western united states a view from the outcrop abstract paleo lakes in the western united states provide geomorphic and hydrologic records of climate and drainage basin change at multiple time scales extending back to the miocene recent reviews and studies of paleo lake records have focused on interpretations of proxies in lake sediment cores from the northern and central parts of the great basin in this review emphasis is placed on equally important studies of lake history during the past 30 years that were derived from outcrop exposures and geomorphology in some cases combined with cores outcrop and core records have different strengths and weaknesses that must be recognized and exploited in the interpretation of paleohydrology and paleoclimate outcrops and landforms can yield direct evidence of lake level facies changes that record details of lake level fluctuations and geologic events such as catastrophic floods drainage basin changes and isostatic rebound cores can potentially yield continuous records when sampled in stable parts of lake basins and can provide proxies for changes in lake level water temperature and chemistry and ecological conditions in the surrounding landscape however proxies such as stable isotopes may be influenced by several competing factors the relative effects of which may be difficult to assess and interpretations may be confounded by geologic events within the drainage basin that were unrecorded or not recognized in a core the best evidence for documenting absolute lake level changes lies within the shore nearshore and deltaic sediments that were deposited across piedmonts and at the mouths of streams as lake level rose and fell we review the different shorezone environments and resulting deposits used in such reconstructions and discuss potential estimation errors lake level studies based on deposits and landforms have provided paleohydrologic records ranging from general changes during the past million years to centennial scale details of fluctuations during the late pleistocene and holocene outcrop studies have documented the integration histories of several important drainage basins including the humboldt amargosa owens and mojave river systems that have evolved since the miocene within the active tectonic setting of the great basin these histories have influenced lake levels in terminal basins many pre late pleistocene lakes in the western great basin were significantly larger and record wetter conditions than the youngest lakes outcrop based lake level data provide important checks on core based proxy interpretations we discuss four such comparisons in some cases such as for lakes owens and manix outcrop and core data synthesis yields stronger and more complete records in other cases such as for bonneville and lahontan conflicts point toward reconsideration of confounding factors in interpretation of core based proxies

surface movements of emplaced lava flows measured by synthetic aperture radar interferometry lava flows continue to move after they have been emplaced by flow mechanisms this movement is largely vertical and can be detected using differential synthetic aperture radar sar interferometry there are three main components to this motion 1 movement of surface scatterers resulting in radar phase decorrelation 2 measurable subsidence of the flow surface due to thermal contraction and clast repacking and 3 time dependent depression of the flow substrate these effects act in proportion to the thickness of the lava flow and decay with time although there is a time lag before the third component becomes significant we explore these effects using sar data from the ers satellites over the etna volcano sicily phase decorrelation on young thick a a lava flows persists for a few years and probably results from surface block rotations during flow contraction maximum measured subsidence rates of the 1991 1993 lava flow over a period of 70 days are about 0 7 mm day 1 but are potentially greater in areas of data decorrelation these rates fall to 2 7 10 2 mm day 1 after about 20 years in flows about 50 m thick sooner for thinner flows comparison with measured subsidence rates on kilauean lava lakes suggests that thermal contraction only accounts for about one third of the observed subsidence the remaining motion is thought to come from surface clast repacking during cooling and from creep mechanisms in the flow substrate measurements of postemplacement surface movement provide new constraints on the thermomechanical properties of lava flows and have cautionary implications for the interpretation of interferometric sar data of volcanoes 2001 american geophysical union

age dating and the orbital theory of the ice ages development of a high resolution 0 to 300 000 year chronostratigraphy using the concept of orbital tuning a continuous high resolution deep sea chronostratigraphy has been developed spanning the last 300 000 yr the chronology is developed using a stacked oxygen isotope stratigraphy and four different orbital tuning approaches each of which is based upon a different assumption concerning the response of the orbital signal recorded in the data each approach yields a separate chronology the error measured by the standard deviation about the average of these four results which represents the best chronology has an average magnitude of only 2500 yr this small value indicates that the chronology produced is insensitive to the specific orbital tuning technique used excellent convergence between chronologies developed using each of five different paleoclimatological indicators from a single core is also obtained the resultant chronology is also insensitive to the specific indicator used the error associated with each tuning approach is estimated independently and propagated through to the average result the resulting error estimate is independent of that associated with the degree of convergence and has an average magnitude of 3500 yr in excellent agreement with the 2500 yr estimate transfer of the final chronology to the stacked record leads to an estimated error of 1500 yr thus the final chronology has an average error of 5000 yr