seasonal and interannual global surface mass variations from multisatellite geodetic data 1 monthly global surface mass distribution changes are estimated in the spherical harmonic domain with a complete spectrum up to degree and order 50 the estimates are derived by inverting gps displacement series measured at roughly 450 continuously tracking sites and ocean bottom pressure obp estimates of a data assimilated ocean circulation model from 1993 to 2004 the inversion uses a hybrid estimator after singular value decomposition of the normalized measurement equations with reduced reliance on a priori spectral information the results are then compared and combined with gravity recovery and climate experiment grace gravity data to provide enhanced spectral and geographic coverage high fidelity degree 1 surface mass variation coefficients are recovered corresponding to equivalent geocenter motion with better than 0 5 mm annual amplitude precisions in all three components a clear annual surface mass cycle occurs in both gps obp and grace derived results there is very good agreement among the low degree spherical harmonic coefficients and in global geographic pattern but with significant regional differences in amplitudes annual variations of average mass over the global oceans antarctica and greenland are then derived total surface mass over both antarctica and greenland peak in their respective summers due to increased atmospheric mass large interannual variations have also been found involving several continents in the 11 year gps obp solution the patterns of variation suggest that the recent satellite laser ranging slr observation of a reversal in trend of the earth s oblateness may be largely an interannual surface mass cycle with considerable contribution from the northern continents

localized analysis of satellite tracking data for studying time variable earth s gravity fields 1 we present a method to analyze the observations of relative distance change between two low earth orbiting satellites of the gravity recovery and climate experiment grace mission after removing the effects caused by the mean gravity field and better known temporal mass redistribution the gravitational acceleration exerted by the block mean mass within a region on the earth surface is formulated by point mass approximation and by spherical harmonic expansion in addition to the regional mass parameters the arc dependent parameters initial relative state vectors is simultaneously modeled to remove the signals not associated with the mass variation within the focus area while a certain level of approximation that is committed when locally formulating the gravitational acceleration vector for numerical integration causes model error we benefit from regionally estimating time variable mass with improved spatial and temporal resolutions in addition various temporal parameterizations depending on geographical areas and expected signals can be applied for the regional analysis in a straightforward manner and it helps to retrieve even sub daily time variable signals such as tides from many years of grace data we present the results of hydrology and ocean tide recovery in south america africa north america and antarctica from the analysis of 3 5 years of grace tracking data and compare them with the traditional global harmonic approach the algorithm development thoroughly described here will be helpful for the science community to exploit fundamental data range rate of the grace mission in addition to monthly gravity products

seismic imaging of melanges pieniny klippen belt case study discussion we appreciate the attempts of marzec et al 2019 to investigate the geological structure of the pieniny klippen belt pkb by means of seismic reflection profiling but in our opinion the authors main conclusions contradict the results of previous studies without being constrained by the new data below we comment on some of the problems that led to the misinterpretation

seasonal clockwise gyration and tilt of the australian continent chasing the center of mass of the earth s system from gps and grace as atmosphere ocean ice and terrestrial water are redistributed the center of mass cm of the earth s system moves and the accompanying loading yields global surface deformation in australia when gps surface displacements were corrected for local mass change hydrology atmosphere and ocean with grace data the residual gps data reveal a peculiar seasonal mode of continental deformation during the southern summer the entire continent coherently shifts northwest by 1 mm and the southeastern part is uplifted while the northwestern part is subsided by 2 3 mm and the opposite patterns of deformation are observed during the southern winter such characteristic deformation could be understood to be a result of the earth s elastic response to globally averaged surface mass load generally heavier in europe during southern summer and in the south pacific ocean during southern winter it was found that such deformation is even larger than local hydrology induced loading effects in horizontal motion over australia a simple method of determining locations of the cm was developed by combining gps and grace data the latter being insensitive to the cm motion but sufficiently accurate to remove the local hydrologic and atmospheric effects in gps data the cm signals are pronounced over systematic errors in gps and grace data the cm coordinates estimated by inversion of the australian gps dataset and grace agree with the geocenter motions determined by satellite tracking analysis this study suggests an independent way of monitoring the cm motion entirely based on two distinct geodetic measurements of gps and grace

surface mass redistribution inversion from global gps deformation and gravity recovery and climate experiment grace gravity data monitoring hydrological redistributions through their integrated gravitational effect is the primary aim of the gravity recovery and climate experiment grace mission time variable gravity data from grace can be uniquely inverted to hydrology since mass transfers located at or near the earth s surface are much larger on shorter timescales than those taking place within the deeper earth and because one can remove the contribution of atmospheric masses from air pressure data yet it has been proposed that at larger scales this may be achieved independently by measuring and inverting the elastic loading associated with redistributing masses e g with the global network of the international gps service igs this is particularly interesting as long as grace monthly gravity solutions do not yet match the targeted baseline accuracies at the lower spherical harmonic degrees in this contribution 1 we describe and investigate an inversion technique which can deal jointly with gps data and monthly grace solutions 2 previous studies with gps data have used least squares estimators and impose solution constraints through low degree spherical harmonic series truncation here we introduce a physically motivated regularization method that guarantees a stable inversion up to higher degrees while seeking to avoid spatial aliasing 3 we apply this technique to gps data provided by the igs service covering recent years we can show that after removing the contribution ascribed to atmospheric pressure loading estimated annual variations of continental scale mass redistribution exhibit pattern similar to those observed with grace and predicted by a global hydrology model although systematic differences appear to be present 4 we compute what the relative contribution of grace and gps would be in a joint inversion using current error estimates gps could contribute with up to 60 to degree 2 till 4 spherical harmonic coefficients and up to 30 for higher degree coefficients

the use of gps horizontals for loading studies with applications to northern california and southeast greenland received 23 august 2012 revised 15 january 2013 accepted 20 january 2013 published 25 april 2013 1 we describe how gps measurements of horizontal crustal motion can be used to augment vertical crustal motion measurements to improve and extend gps studies of surface loading we show that the ratio of the vertical displacement to the horizontal displacement combined with the direction of the horizontal motion can help determine whether nearby loading is concentrated in a small region for example in a single lake or glacier and where that region is we illustrate this method by applying it to two specific cases an analysis of gps data from northern california to monitor the level of lake shasta and the analysis of data from a single gps site in southeast greenland to determine mass variability of two large nearby outletglaciers helheim glacier and midgaard glacier the californiaexampleserves largely as a proof of concept where the results can be assessed by comparing with independent observations lake shasta tide gauge data in this case our greenland results show that both helheim and midgaard have experienced notable interannual variations in mass loss rate over the last decade helheim sm ass loss accelerated rapidly in mid 2003 decelerated in late 2005 and increased again in 2008 2009 before returning to about its pre 2003 rate in late 2010 midgaard s mass loss accelerated in mid 2004 and remained more or less constant before returning to its pre 2003 rate in late 2008

seismic imaging of melanges pieniny klippen belt case study the authors present results of the first high resolution deep seismic reflection survey in the pieniny klippen belt pkb in poland this survey sheds new light on the matter of olistostromes and the melange character of the pkb the sedimentary mass transport deposits represented by olistoliths and olistostromes manifest themselves by different petrophysical parameters of rocks velocity density and resistivity and seismic attributes seismic attributes are very effective in the interpretation of the geology of complex melanges the authors used selected attributes low pass filter energy energy gradient dip steered median filter prewitt filter laplacian edge enhancing filter and square root of the energy gradient these attributes emphasize changes of the seismic image inside melange zones the distinguished olistoliths are now inside imbricated thrust structures and they are tectonically rearranged polygenetic melanges in the pkb originated as a result of sedimentary and tectonic processes the pkb in the investigated area forms several north vergent thrust sheets belonging to the zlatne and hulina nappes both nappes contain large chaotic non reflective olistoliths as well as the smaller mainly high reflective olistoliths olistoliths are arranged parallel to the flysch layering and thrusts the results presented confirm the postulated two olistostrome belts within the pkb structure

atmospheric effects and spurious signals in gps analyses improvements in the analyses of global positioning system gps obser vations yield resolvable mm to sub mm di erences in coordinate estimates thus provid ing su cient resolution to distinguish subtle di erences in analysis methodologies here we investigate the e ects on site coordinates of using di erent approaches to modelling atmospheric loading deformation atml and handling of tropospheric delays the rig orous approach of using the time varying vmf1 mapping function yields solutions with lower noise at a range of frequencies compared with solutions generated using empiri cal mapping functions this is particularly evident when atml is accounted for some improvement also arises from using improved a priori zenith hydrostatic delays zhd with the combined e ect being site speci c importantly inadequacies in both mapping functions and a priori zhds not only introduce time correlated noise but signi cant pe riodic terms at solar annual and semi annual periods we nd no signi cant di erence between solutions where non tidal atml is applied at the observation level rather than as a daily averaged value but failing to model diurnal and semi diurnal tidal atml at the observation level can introduce anomalous propagated signals with periods that closely match the gps draconitic annual 351 4 d and semi annual period 175 7 d ex acerbated by not xing ambiguities these signals are evident in both stacked and sin gle site power spectra with each tide contributing roughly equally to the dominant semi annual peak the amplitude of the propagated signal reaches a maximum of 0 8 mm with a clear latitudinal dependence that is not correlated directly with locations of maximum tidal amplitude this is the first evidence of aliased signals being produced from tidal atml deformations

climate driven deformation of the solid earth from grace and gps 1 grace data indicate large seasonal variations in gravity that are assumed to be related to climate driven fluxes of surface water seasonal redistribution of surface mass should deform the earth and our calculations using grace data suggest vertical deformations of 13 mm in the region of greatest flux the amazon river basin to test the grace gravity hydrology connection we analyzed gps data acquired from sites in this region after accounting for degree 1 variations not observable with grace we find that annual deformation measured with gps correlates highly with predictions calculated from grace measurements these results confirm the variations in surface water sensed by grace which are significantly larger than those predicted by some hydrology models the results also demonstrate that grace can be an important tool for monitoring deformation of the earth and suggest that combined analysis of grace and gps may be a useful approach for estimation of geocenter variations

improved methods for observing earth s time variable mass distribution with grace using spherical cap mascons we discuss several classes of improvements to gravity solutions from the gravity recovery and climate experiment grace mission these include both improvements in background geophysical models and orbital parameterization leading to the unconstrained spherical harmonic solution jpl rl05 and an alternate jpl rl05m mass concentration mascon solution benefitting from those same improvements but derived in surface spherical cap mascons the mascon basis functions allow for convenient application of a priori information derived from near global geophysical models to prevent striping in the solutions the resulting mass flux solutions are shown to suffer less from leakage errors than harmonic solutions and do not necessitate empirical filters to remove north south stripes lowering the dependence on using scale factors the global mean scale factor decreases by 0 17 to gain accurate mass estimates ocean bottom pressure obp time series derived from the mascon solutions are shown to have greater correlation with in situ data than do spherical harmonic solutions increase in correlation coefficient of 0 08 globally particularly in low latitude regions with small signal power increase in correlation coefficient of 0 35 regionally in addition to reducing the error rms with respect to the in situ data reduction of 0 37 cm globally and as much as 1 cm regionally greenland and antarctica mass balance estimates derived from the mascon solutions agree within formal uncertainties with previously published results computing basin averages for hydrology applications shows general agreement between harmonic and mascon solutions for large basins however mascon solutions typically have greater resolution for smaller spatial regions in particular when studying secular signals

geophysical interpretation of observed geocenter variations geocenter variations are caused by mass redistribution within the earth system especially the atmosphere oceans and continental water using surface pressure fields and soil moisture and snow depth fields of the ncep ncar climate data assimilation system i cdas i 1 we estimate contributions from variations in atmospheric surface pressure and continental water storage to the earth s geocenter center of mass variation in addition sea surface anomalies determined by the topex poseidon altimeter are used to investigate geocenter variations resulting from ocean mass redistribution these sea surface height data were corrected using a simplified steric model a comparison with observed geocenter variations derived from lageos 1 and 2 satellite laser ranging data indicates that the atmosphere oceans and continental hydrological cycle all provide significant contributions at different frequencies geocenter variations estimated in this paper are in reasonably good agreement with results given by dong et al 1997 for atmospheric and ocean contributions but not for the estimates of continental hydrological contributions

horizontal motion in elastic response to seasonal loading of rain water in the amazon basin and monsoon water in southeast asia observed by gps and inferred from grace 1 we find seasonal horizontal crustal motions observed by gps positioning in elastic response to heavy rainfall in the amazon basin and to monsoons in southeast asia to be consistent with those inferred from gravity recovery and climate experiment grace gravity observations of water mass loading solid earth moves toward the amazon during heavy spring rainfall and toward southeast asia during summer monsoons and back away from these areas 6 months later when the water load is minimum vertical oscillations observed by gps and inferred from grace are 2 to 3 times larger than horizontal oscillation near the margins of the areas of large mass loading some discrepancies between gps and grace are probably caused by local effects that influence gps measurements because the gps sites that show significant discrepancies also do not match nearby gps sites however when the load is short wavelength the limited spatial resolution of grace can cause systematic misfits

snow load effect on the earth s rotation and gravitational field 1979 1985 a global monthly snow depth data set has been generated from the nimbus 7 satellite observations using passive microwave remote sensing techniques in this paper we analyze 7 years of data 1979 1985 to compute the snow load effects on the earth s rotation and low degree zonal gravitational field a uniform sea level decrease has been assumed in order to conserve water mass the resultant time series show dominant seasonal cycles the annual peak to peak variation in j2 is found to be 2 3 x 10 o that in j3 to be 1 1 x 10 o and believed to decrease rapidly for higher degrees the corresponding change in the length of day is 41 us the annual wobble excitation is 4 9 marc sec 109 o for the prograde motion component and 4 8 marc sec 28 o for the retrograde motion component the excitation power of the chandler wobble due to the snow load is estimated to be about 25 db less than the power needed to maintain the observed chandler wobble the superior quality of the satellite data over conventional data acquired by ground observations and modeling is demonstrated we also discuss the role of atmospheric water and the problems arising from the lack of snow load observations over the antarctic and greenland ice sheets

source parameter inversion for recent great earthquakes from a decade long observation of global gravity fields we quantify gravity changes after great earthquakes present within the 10 year long time series of monthly gravity recovery and climate experiment grace gravity fields using spherical harmonic normal mode formulation the respective source parameters of moment tensor and double couple were estimated for the 2004 sumatra andaman earthquake the gravity data indicate a composite moment of 1 2 1023 n m with a dip of 10 in agreement with the estimate obtained at ultralong seismic periods for the 2010 maule earthquake the grace solutions range from 2 0 to 2 7 1022 n m for dips of 12 24 and centroid depths within the lower crust for the 2011 tohoku oki earthquake the estimated scalar moments range from 4 1 to 6 1 1022 n m with dips of 9 19 and centroid depths within the lower crust for the 2012 indian ocean strike slip earthquakes the gravity data delineate a composite moment of 1 9 1022 n m regardless of the centroid depth comparing favorably with the total moment of the main ruptures and aftershocks the smallest event we successfully analyzed with grace was the 2007 bengkulu earthquake with m0 5 0 1021 n m we found that the gravity data constrain the focal mechanism with the centroid only within the upper and lower crustal layers for thrust events deeper sources i e in the upper mantle could not reproduce the gravity observation as the larger rigidity and bulk modulus at mantle depths inhibit the interior from changing its volume thus reducing the negative gravity component focal mechanisms and seismic moments obtained in this study represent the behavior of the sources on temporal and spatial scales exceeding the seismic and geodetic spectrum

reply to the seismic imaging of melanges pieniny klippen belt case study discussion we welcome the discussion by jurewicz et al 2020 whose main criticism focused on the fact that the authors main conclusions contradict the results of previous studies however this statement refers perhaps to the geological setting since we are not aware of any previous studies providing seismic imaging of melanges in the pieniny klippen belt pkb we did not consider the critical remarks by plasienka et al 2017 because we believe that sufficient answers were provided by golonka et al 2017 we are grateful to jurewicz et al 2020 for pointing out the erroneous term tectonic olistolith that we will correct it in future work the discussion is based on two sets of problems regional geology and interpretations of seismic data

discussion of olistostromes of the pieniny klippen belt northern carpathians j golonka m krobicki a wa kowska m cieszkowski a l czka reply we welcome the comments by our slovakian colleagues and their critique of our results particularly as we have discussed and published papers together several times about our ideas sometimes more or less disputable aubrecht et al 2003 2006 krobicki et al 2003 krobicki aubrecht golonka 2003 golonka et al 2006 pienkowski et al 2008 we are pleased to see such warm reaction to our work paper which is focused on one of the rudimentary questions in the pieniny klippen belt pkb area how many what kind of olistoliths olistostromes occur within the inner structure of the pkb and when and why did they originate mostly during the palaeogene part of the mesozoic cenozoic history of this region we expected this discussion earlier the content of our paper was presented at the 6 th meeting of the central european tectonic studies group ceteg in upohlav pieniny klippen belt slovakia cieszkowski et al 2008 and later at the xix congress of the carpathian balkan geological association in thessaloniki greece cieszkowski et al 2010 golonka et al 2010 some ideas were also briefly mentioned in the paper by cieszkowski et al 2009 in a journal issue edited by d plasienka we assume that the comments are based on recent investigation because the authors list the grants received to conduct the research therefore the submitted comments sometimes present a point of view different from that published previously by some of the authors of the comments ra jm see aubrecht et al 2003 krobicki aubrecht golonka 2003 wierzbowski et al 2006 pienkowski et al 2008 the statement certainly there are many still unresolved problems in the geology of the pkb and it ought to be said that the co authors of this discussion also do not fully agree with all interpretations formulated and illustrated by the first author perhaps explains this controversy of course we agree that there are many still unresolved problems in the geology of the pkb we also agree with the statement olistostromes and olistoliths are quite frequent but not omnipresent we depicted the distribution of the olistoliths and their relationship to the non olistolith tectonic units of the pkb in golonka et al 2015 figs 3 8

a new global mode of earth deformation seasonal cycle detected we have detected a global mode of earth deformation that is predicted by theory precise positioning of global positioning system sites distributed worldwide reveals that during february to march the northern hemisphere compresses and the southern hemisphere expands such that sites near the north pole move downward by 3 0 millimeters and sites near the equator are pulled northward by 1 5 millimeters the opposite pattern of deformation occurs during august to september we identify this pattern as the degree one spherical harmonic response of an elastic earth to increased winter loading of soil moisture snow cover and atmosphere data inversion shows the load moment s trajectory as a great circle traversing the continents peaking at 6 9 1022 kilogram meters near the north pole in winter indicating interhemispheric mass exchange of 1 0 1016 0 2 1016 kilograms

hydrological deformation induced by the west african monsoon comparison of gps grace and loading models three dimensional ground deformation measured with permanent gps stations in west africa was used for investigating the hydrological loading deformation associated with monsoon precipitation the gps data were processed within a global network for the 2003 2008 period weekly station positions were retrieved with a repeatability including unmodeled loading effects of 1 2 mm in the horizontal components and between 2 5 and 6 mm in the vertical component the annual signal in the vertical component for sites located between 9 6n and 16 7n is in the range 10 15 mm it is consistent at the 3 mm level with the annual regional scale loading deformations estimated from grace satellite products and modeled with a combination of hydrological atmospheric and nontidal oceanic models an additional 6 month transient signal was detected in the vertical component of gps estimates at most of the west african sites it takes the form of an oscillation occurring between september and march and reaching a maximum amplitude of 12 16 mm at ouagadougou 12 5n the analysis of in situ hydro geological data revealed a strong coincidence between this transient signal and peak river discharge at three sites located along the niger river timbuktu gao and niamey at ouagadougou a similar coincidence was found with the seasonal variations of the water table depth we propose a mechanism to account for this signal that involves a sequence of swelling shrinking of clays combined with local loading effects associated with flooding of the niger river

textural and sequence stratigraphic controls on sealing capacity of lower and upper cretaceous shales denver basin colorado shale units can be important barriers to fluid flow in sedimentary basins and commonly serve as seals to petroleum reservoirs little is known however about the controls on shale permeability consequently variation in seal competency is one of the greatest risk factors associated with petroleum exploration here we examine possible controls on sealing capacity in two cretaceous marine shale units in the denver basin colorado sealing capacity as determined by mercury injection capillary pressure analysis is compared to several textural and compositional parameters and to sequence stratigraphic setting these two shale units display highly variable sealing capacity even between some adjacent samples this suggests that variability in some small scale shale characteristics may strongly influence sealing capacity the best seals are generally in transgressive systems tracts especially within or immediately below condensed sections textural characteristics of shale appear to be especially important in determining sealing capacity in particular well sorted pore throat sizes and well developed bedding parallel preferred orientation of flattened organic matter particles strongly favor high sealing capacity high degrees of bioturbation degrade sealing capacity possibly by disrupting preferred orientation and by increasing variability in grain size and hence in pore throat sorting preferred orientation of matrix clays parallel to bedding also appears to increase with increasing sealing capacity but is probably less important than the preferred orientation of organic matter compositional characteristics are generally less important than textural characteristics in determining sealing capacity in these shale units neither silt content nor cement content appears to be important to sealing capacity in these shale units total organic carbon is generally high in samples with good sealing capacity but can be either high or low where sealing capacity is poor overall the variables that most strongly favor high sealing capacity pore throat sorting organic matter bedding parallel preferred orientation and low bioturbation are most likely in anoxic deep water settings hence the association between good seals and condensed sections

troposphere mapping functions for gps and very long baseline interferometry from european centre for medium range weather forecasts operational analysis data 1 in the analyses of geodetic very long baseline interferometry vlbi and gps data the analytic form used for mapping of the atmosphere delay from zenith to the line of site is most often a three parameter continued fraction in 1 sin elevation using the 40 years reanalysis era 40 data of the european centre for medium range weather forecasts for the year 2001 the b and c coefficients of the continued fraction form for the hydrostatic mapping functions have been redetermined unlike previous mapping functions based on data from numerical weather models isobaric mapping functions niell 2000 and vienna mapping functions vmf boehm and schuh 2004 the new c coefficients are dependent on the day of the year and unlike the niell mapping functions niell 1996 they are no longer symmetric with respect to the equator apart from the opposite phase for the two hemispheres compared to vmf this causes an effect on the vlbi or gps station heights that is constant and as large as 2 mm at the equator and that varies seasonally between 4 mm and 0 mm at the poles the updated vmf based on these new coefficients and called vmf1 hereinafter yields slightly better baseline length repeatabilities for vlbi data the hydrostatic and wet mapping functions are applied in various combinations with different kinds of a priori zenith delays in the analyses of all vlbi international vlbi service for geodesy and astrometry ivs r1 and ivs r4 24 hour sessions of 2002 and 2003 the investigations concentrate on baseline length repeatabilities as well as on absolute changes of station heights

ongoing drought induced uplift in the western united states the western united states has been experiencing severe drought since 2013 the solid earth response to the accompanying loss of surface and near surface water mass should be a broad region of uplift we use seasonally adjusted time series from continuously operating gps stations to measure this uplift which we invert to estimate mass loss the median uplift is 4 mm with values up to 15 mm in california s mountains the associated pattern of mass loss which ranges up to 50 cm of water equivalent is consistent with observed decreases in precipitation and streamflow we estimate the total deficit to be about 240 gt equivalent to a 10 cm layer of water over the entire region or the annual mass loss from the greenland ice sheet

inversion of earth s changing shape to weigh sea level in static equilibrium with surface mass redistribution 1 we develop a spectral inversion method for mass redistribution on the earth s surface given geodetic measurements of the solid earth s geometrical shape using the elastic load love numbers first spectral coefficients are geodetically estimated to some degree spatial inversion then finds the continental surface mass distribution that would force geographic variations in relative sea level such that it is self consistent with an equipotential top surface and the deformed ocean bottom surface and such that the total ocean plus continental mass load has the same estimated spectral coefficients applying this theory we calculate the contribution of seasonal interhemispheric degree 1 mass transfer to variation in global mean sea level and nonsteric static ocean topography using published gps results for seasonal degree 1 surface loading from the global igs network our inversion yields ocean continent mass exchange with annual amplitude 2 92 0 14 1015 kg and maximum ocean mass on 25 august 3 days after correction for the annual variation in global mean vertical deformation of the ocean floor 0 4 mm amplitude we find geocentric sea level has an amplitude of 7 6 0 4 mm consistent with topex poseidon results minus steric effects the seasonal variation in sea level at a point strongly depends on location ranging from 3 to 19 mm the largest being around antarctica in mid august seasonal gradients in static topography have amplitudes of up to 10 mm over 5000 km which may be misinterpreted as dynamic topography peak continental loads occur at high latitudes in late winter at the water equivalent level of 100 200 mm

a decade of horizontal deformation from great earthquakes 1 the 21st century has seen the occurrence of 17 great earthquakes mw 8 including some of the largest earthquakes ever recorded numerical modeling of the earthquakes shows that nearly half of the earth s surface has undergone horizontal coseismic deformation 1 mm with the 2004 sumatra andaman earthquake dominating the global deformation field this has important implications for both the realization of a terrestrial reference frame and in the interpretation of regional tectonic studies based on gps velocities we show that far field coseismic deformations from great earthquakes will if unaccounted for introduce errors in estimates of linear site velocities of at least 0 1 0 3 mm yr across most of the surface of the earth the accumulated global deformation field shows that two regions australia and the north atlantic arctic ocean have been largely undeformed by these great earthquakes with accumulated deformations generally 0 5 mm using gps estimates of surface deformation we show that the majority of the australian continent is deforming at 0 2 mm yr the northern part of new zealand is rotating clockwise relative to the australian plate with relative horizontal velocities of 2 mm yr while the southeastern coast of australia is undergoing post seismic relaxation caused by the 2004 mw 8 1 macquarie ridge earthquake the presence of ongoing post seismic relaxation thousands of kilometers from plate margins violates the secular linear assumption made in current terrestrial reference frame definitions these effects have significant ramifications for regional tectonic interpretations and global studies such as sea level rise that require reference frame accuracy greater than this level

estimating geocenter variations from a combination of grace and ocean model output 1 in this study we estimate a time series of geocenter anomalies from a combination of data from the gravityrecoveryandclimateexperiment grace satellitemissionandthe outputfromoceanmodels amatrixequationisderivedrelating totalgeocentervariations to the grace coefficients of degrees two and higher and to the oceanic component of the degree one coefficients we estimate the oceanic component from two state of the art ocean models results are compared to independent estimates of geocenter derived from other satellite data such as satellite laser ranging and gps finally we compute degree one coefficients that are consistent with the processing applied to the grace level 2 gravity field coefficients the estimated degree one coefficients can be used to improve estimates of mass variability from grace which alone cannot provide them directly

discussion of olistostromes of the pieniny klippen belt northern carpathians d plasienka j michalik j sotak r aubrecht comment in their recent paper golonka et al 2015 described the cretaceous and palaeogene olistostromes and other types of mass transport deposits occurring within the pieniny klippen belt pkb of the western carpathians after a short introduction into the olistostrome concept and an overall description of the pkb structure the authors presented their views on the composition and evolution of the pkb with olistostromes as the leading phenomenon although novel in some aspects the model they present is largely oversimplified and partly erroneous in our opinion in the following we shall comment on the several most disputable statements and interpretations offered in the discussed paper