separation of coseismic and postseismic gravity changes for the 2004 sumatra andaman earthquake from 4 6 yr of grace observations and modelling of the coseismic change by normal modes summation eodspatiale grgs for comparison the release 04 solutions of the center for space research csr are also inves tigated after a spectral windowing or a gaussian spatial smoothing results are shown both in terms of geoid height changes and gravity variations coseismic and postseismic gravitational changes estimated from the different gravity solutions are globally similar although their spa tial extent and amplitude depend on the type of filter used in the processing of grace fields the highest signal to noise ratio is found with the grgs solutions the postseismic signature has a spectral content closer to the grace bandwidth than the coseismic signature and is therefore better detected by grace the coseismic signature consists mainly of a strong gravity decrease east of the sunda trench in the andaman sea a gravity increase is also detected at a smaller scale west of the trench the model for the coseismic gravity changes agrees well with the coseismic signature estimated from grace regarding the overall shape and orientation location with respect to the trench and order of magnitude coseismic gravity changes are followed by a postseismic relaxation that are well fitted by an increasing expo nential function with a mean relaxation time of 0 7 yr the total postseismic gravity change consists of a large scale positive anomaly centred above the trench and extending over 15 of latitude along the subduction after 26 months the coseismic gravity decrease has been partly compensated by the postseismic relaxation but a negative anomaly still remains south of phuket a dominant gravity increase extends over 15 of latitude west of the trench being maximal south of the epicentre area by investigating analyses of two global hydrology models and one ocean general circulation model we show that our grace estimates of the coseismic and postseismic gravitational changes are almost not biased by interannual variations originat ing from continental hydrology and ocean circulation in the subduction area and in the central part of the andaman sea while they are biased by several gal in the malay peninsula

structure and evolution of the 22 february 1993 toga coare squall line organization mechanisms inferred from numerical simulation abstract mechanisms responsible for meso and convective scale organization within a large tropical squall line that occurred on 22 february 1993 during the tropical ocean global atmosphere coupled ocean atmosphere response experiment are investigated using a three dimensional numerical cloud model the squall line occurred in an environment typical of fast moving tropical squall lines characterized by moderate convective available potential energy and moderate to strong vertical shear beneath a low level jet with weak reverse vertical shear above a well simulated aspect of the observed squall line is the evolution of a portion of its leading convective zone from a quasi linear to a three dimensional bow shaped structure over a 2 h period this transition is accompanied by the development of both a prominent mesoscale vortex along the northern edge of the 40 60 km long bow shaped feature and elongated bands of weaker reflectivity situated rearward and oriented transverse to the leading edge within enha

coseismic gravity changes of the 2010 earthquake in central chile from satellite gravimetry 1 the first map of coseismic changes in gravity and geoid height has been drawn using the data from the gravity recovery and climate experiment grace satellites for the 2004 sumatra andaman earthquake here we present the second case of coseismic gravity change observation by satellite gravimetry i e the change caused by an interplate thrust earthquake that occurred on 27 february 2010 in central chile mw 8 8 gravity showed a negative jump with the largest drop of 5 gal on the back arc side the observed changes agree with those calculated assuming the realistic earth and fault parameters inferred from coseismic displacements of global positioning system gps stations gravity in this area shows large seasonal and inter annual variability and postseismic gravity changes could be isolated only by carefully removing hydrological signals

a source model for the great 2011 tohoku earthquake mw 9 1 from inversion of grace gravity data abstract the co seismic slip distribution of the 2011 tohoku megathrust earthquake is constrained from geoforschungszentrum gfz gravity recovery and climate experiment grace level 2 data time series and our self gravitating compressible 1 d earth model after spatial localization of space gravity data in the surrounding of the u s geological survey usgs epicenter by means of orthogonal slepian functions we estimate the long wavelength co seismic gravity signature the pattern is bipolar the positive pole off shore in the pacific ocean 3 6 gal and the negative pole in the northern japan and japan sea 8 6 gal inversion of the grace data resolves average features of finite fault models the total seismic moment 5 3 1 10 22 nm corresponding to m w 9 1 in agreement with the centroid moment tensor solution the rake angle 87 9 and the mean position of the slip distribution on the fault plane we obtain that the mean depth of the rupture is 17 1 5 km just below the moho discontinuity although we cannot exclude that the rupture also extended to shallower crustal layers and deeper within the lithospheric mantle due to the poor resolution of the along dip dimension of the fault

crustal dilatation observed by grace after the 2004 sumatra andaman earthquake we report the detection of an earthquake by a space based measurement the gravity recovery and climate experiment grace satellites observed a 15 microgalileo gravity change induced by the great december 2004 sumatra andaman earthquake coseismic deformation produces sudden changes in the gravity field by vertical displacement of earth s layered density structure and by changing the densities of the crust and mantle grace s sensitivity to the long spatial wavelength of gravity changes resulted in roughly equal contributions of vertical displacement and dilatation effects in the gravity measurements the grace observations provide evidence of crustal dilatation resulting from an undersea earthquake

ocean contribution to co seismic crustal deformation and geoid anomalies application to the 2004 december 26 sumatra andaman earthquake large earthquakes do not only heavily deform the crust in the vicinity of the fault they also change the gravity field of the area affected by the earthquake due to mass redistribution in the upper layers of the earth besides that for sub oceanic earthquakes deformation of the ocean floor causes relative sea level changes and mass redistribution of water that have again a significant effect on the gravity field to model these deformations sea level changes and gravity field perturbations self consistently we use an adapted version of the sea level equation sle that has been used for glacial isostatic adjustment studies the sea level equation next to our normal mode model for seismic solid earth modeling allows us to compute a gravitationally self consistent solution for the co seismic relative sea level surface deformation and geoid height changes we apply our geographically detailed models to the case of the 2004 december 26 sumatra andaman earthquake recent studies that have modeled the ocean mass effect on co seismic gravity change for this specific earthquake show model results that indicate a broad negative change in geoid height around the fault due to ocean water redistribution de linage et al 2009 melini et al 2010 our model results for the ocean contribution to geoid height differ from these studies in the sense that we find a pattern similar to the elongated dipole pattern of the solid earth model outputs for gravity and vertical deformation together with a relatively small broad negative geoid height change we explain the relation between outcomes for geoid height relative sea level and vertical deformation of the ocean floor and we confront our model results with a least squares estimation of the co seismic discontinuity in grace derived gravity field time series we show that taking into account the contribution of ocean water redistribution to the co seismic geoid height change next to a compressible solid earth model is essential to explain the predominant negative co seismic geoid anomalies from the grace gravity field solutions besides we introduce a detailed approach to modeling an earthquake in a normal mode model that better approximates realistic continuous slip on the fault plane than models that do not distribute slip with depth to demonstrate the importance of the slip distribution we show the differences in outcomes for modeled geoid height and vertical deformation

co seismic deformation following the 2007 bengkulu earthquake constrained by grace and gps observations abstract gravity changes caused by giant earthquakes can be detected by gravity recovery and climate experiment grace which provide new constraints on earthquake ruptures however detailed rupture seismic moment and density displacement induced gravity changes are not clear for less than mw 8 5 earthquakes in this paper the fault parameters of the 2007 mw 8 4 bengkulu earthquake are retrieved from grace and gps data and the fault slip distribution is inverted using gps data furthermore the theoretical coseismic displacements and coseismic gravity changes from different slip models are compared with gps and grace data the results show that the significant positive and negative gravity anomalies with a peak magnitude of 2 0 to 1 3 gal are extracted from grace data the grace inverted and joint inverted seismic moment of the bengkulu earthquake are 3 27 10 21 nm and 3 30 10 21 nm with the rake angle of 108 and 114 respectively the gps inverted mw 8 4 earthquake is mainly dominated by the thrusting with slight right lateral strike slip which is consistent with the focal mechanism grace observed coseismic gravity changes agree well with the results from the fault models based on the spherically dislocation theories in spatial pattern but are larger than model estimated results in magnitude the coseismic gravity changes caused by the density change are basically same as those caused by the vertical displacement in the magnitude of order which are 0 8 to 0 2 gal and 0 2 to 1 4 gal for the caltech model 0 9 to 0 2 gal and 0 5 to 1 3 gal for the usgs model and 0 9 to 0 2 gal and 0 3 to 1 3 gal for the gps inverted layered model in addition both the near field and the far field displacements calculated from the caltech model and gps inverted layered model are in good agreement with the gps observations whereas the usgs model has good agreement in the far field and poor agreement in the near field with the gps observations especially in the pagai selatan area

a three dimensional simulation of a tropical squall line convective organization and thermodynamic vertical transport abstract three dimensional convective scale simulations of an african squall line observed during the french copt 81 experiment are presented three simulations with different representations of large scale forcing are performed on a domain of 50 km along the line by 80 km across the line they exhibit a similar circulation pattern characteristic of a squall line but differ in intensity the first simulation supposes an unperturbed environment and produces a slow moving squall line 7 m s 1 with weaker total precipitation rate then observed 25 the second one includes a representation of observed thermodynamic and dynamic environment modifications and produces a fast moving squall line 10 m s 1 still weaker than observations 50 or the rain rate the third simulation takes into account the forcing induced by the rear inflow jet as depicted by smull and houze and observed on that day it allows the system to reach an intensity in agreement with observations the convective region 30 km wid

topographic effects on coseismic gravity change for the 2011 tohoku oki earthquake and comparison with grace we estimate gravity changes due to coseismic horizontal deformation and inclined bathymetry referred to as topographic effects in this study associated with the 2011 tohoku oki earthquake using a layered half space dislocation model as an approximation we represent inclined topography with ramp body models in the near field of the earthquake and calculate topographic effects from both an inclined seafloor and moho the moho effect partly compensates that from the seafloor an additional contribution comes from seawater column variations as the sloped seafloor moves trenchward topographic effects are first order contributions to coseismic gravity changes for the 2011 tohoku oki earthquake after 300 km gaussian smoothing comparable to the spatial resolution of the gravity recovery and climate experiment grace topographic effects create a dominantly negative gravity pattern with amplitudes up to 1 1 gal for oceanic areas surrounding the epicenter there are discrepancies between model predictions 10 4 to 6 9 gal and grace observations 10 1 to 1 7 gal errors in the adopted fault slip model and difficulties in separating coseismic and postseismic deformation may contribute to these but topographic effects currently neglected in dislocation models are also responsible topographic effects ought to be included in coseismic fault slip and related gravity modeling for the 2011 tohoku oki earthquake and similar events in regions of steep topography

distributed fault slip model for the 2011 tohoku oki earthquake from gnss and grace goce satellite gravimetry the gravity recovery and climate experiment grace mission launched 2002 and the gravity field and steady state ocean circulation explorer goce mission march 2009 to november 2013 collected spaceborne gravity data for the preseismic and postseismic periods of the 2011 tohoku oki earthquake in addition the dense japan geonet global navigation satellite systems gnss network measured with approximately 1050 stations the coseismic and postseismic surface displacements we use a novel combination of gnss grace and goce observations for a distributed fault slip model addressing the issues with gravimetric and geometric change over consistent time windows our model integrates the coseismic and postseismic effects as we include goce observations averaged over a 2 year interval but their inclusion reveals the gravity change with unprecedented spatial accuracy the gravity gradient grid evaluated at goce orbit height of 265 km has an estimated formal error of 0 20 me which provides sensitivity to the mainly coseismic and integrated postseismic induced gravity gradient signal of 1 03 me we show that an increased resolution of the gravity change provides valuable information with goce gravity gradient observations sensitive to a more focused slip distribution in contrast to the filtered grace equivalent the 2 year averaging window of the observations makes it important to incorporate estimates of the variance covariance of unmodeled processes in the inversion the gnss and grace goce combined model shows a slip pattern with 20 m peak slip at the trench the total gravity change 200 gal and the spatial mapping accuracy would have been considerably lower by omitting the goce derived fine scale gravity field information

migrating pattern of deformation prior to the tohoku oki earthquake revealed by grace data understanding how and when far field continuous motions lead to giant subduction earthquakes remains a challenge an important limitation comes from an incomplete description of aseismic mass fluxes at depth along plate boundaries here we analyse earth s gravity field variations derived from grace satellite data in a wide space time domain surrounding the mw 9 0 2011 tohoku oki earthquake we show that this earthquake is the extreme expression of initially silent deformation migrating from depth to the surface across the entire subduction system our analysis indeed reveals large scale gravity and mass changes throughout three tectonic plates and connected slabs starting a few months before march 2011 before the tohoku oki earthquake rupture the gravity variations can be explained by aseismic extension of the pacific plate slab at mid upper mantle depth concomitant with increasing seismicity in the shallower slab for more than two years after the rupture the deformation propagated far into the pacific and philippine sea plate interiors suggesting that subduction accelerated along 2 000 km of the plate boundaries in march 2011 this gravitational image of the earthquake s long term dynamics provides unique information on deep and crustal processes over intermediate timescales which could be used in seismic hazard assessment deformation migrated from depth towards the surface in the months leading up to the 2011 tohoku oki earthquake according to analyses of satellite gravity data

coseismic and post seismic signatures of the sumatra 2004 december and 2005 march earthquakes in grace satellite gravity s u m m a r y the grace satellite mission has been measuring the earth s gravity field and its temporal variations since 2002 april although these variations are mainly due to mass transfer within the geofluid envelops they also result from mass displacements associated with phenomena including glacial isostatic adjustment and earthquakes however these last contributions are difficult to isolate because of the presence of noise and of geofluid signals and because of grace s coarse spatial resolution 400 km half wavelength in this paper we show that a wavelet analysis on the sphere helps to retrieve earthquake signatures from grace geoid products using a wavelet analysis of grace geoids products we show that the geoid variations caused by the 2004 december m w 9 2 and 2005 march m w 8 7 sumatra earthquakes can be detected at grace resolution the 2004 december earthquake produced a strong coseismic decrease of the gravity field in the andaman sea followed by relaxation in the area affected by both the andaman 2004 and the nias 2005 earthquakes we find two characteristic timescales for the relaxation with a fast variation occurring in the vicinity of the central andaman ridge we discuss our coseismic observations in terms of density changes of crustal and upper mantle rocks and of the vertical displacements in the andaman sea we interpret the post seismic signal in terms of the viscoelastic response of the earth s mantle the transient component of the relaxation may indicate the presence of hot viscous material beneath the active central andaman basin

numerical study of a sahelian synoptic weather system initiation and mature stages of convection and its interactions with the large scale dynamics summary a 24 h multi scale simulation of the life cycle of a sahelian squall line is presented the initial and coupling e elds have been taken from the european centre for medium range weather forecasts re analysis era 15 after humidity corrections to avoid spurious absolute and conditional convective instabilities comparisons of modelsynthetic and meteosat infra red radiances indicate that the simulated scenario of convection development and structure are realistic though differences are found concerning the size of the squall line with a delay of 2 3 h the simulated arc shaped structure and surface signature e t well with radar and ground station observations respectively the mature stage of the simulated squall line presents a cross line structure similar to conceptual models an intense rear to front e ow is generated below the trailing stratiform part an acceleration of the african easterly jet aej is simulated behind the system occurring across its full width this leads to the generation of a dipole of counter rotating vortices the resulting potential vorticity signature leads to local reinforcement of the barotropic instability on the north e ank of the aej this simulation is used to analyse the impact of the convection at synoptic scales and to compare it with era 15 it suggests that the convection contributes to reinforce the monsoon at least up to 500 km the monsoon ine ow moves eastward and westward with time scales shorter and longer than 24 h respectively the tropical easterly jet intensie es to the south west of the convection area up to 700 km away the aej is strongly intensie ed ahead of the trough where active convection occurs organized convection developing in the vicinity of the aej core induces weakening of the aej ahead of the squall line and strengthening behind it a common result in the simulation and in era 15 is that the aej core moves westward faster due to the convective activity

daytime boundary layer evolution over mountainous terrain part 1 observations of the dry circulations abstract this paper presents the boundary layer structure which accompanies the development of daytime local wind systems in a broad mountain valley as revealed by cross sections of potential temperature it describes how this structure leads to the occurrence of a region of convergence to the downwind side of mountains previous studies based primarily on one dimensional sounding of potential temperature and horizontal winds have shown that profiles of static stability and the presence of winds aloft have an important effect on the manner in which daytime thermally forced wind systems develop in the present study two dimensional cross sections obtained from aircraft data vertical soundings and surface mesonet data show several relevant features in mid to late morning near the surface for example upslope winds form in a shallow mixed layer at the underside of the nocturnal inversion layer cold pool at elevations above the top of this cold pool convectively mixed surface winds exist the spat

formulation of coseismic changes in earth rotation and low degree gravity field based on the spherical earth dislocation theory in this paper we present analytical formulas to compute the coseismic earth rotation change polar motion and length of day and low degree gravity field change based on a spherical dislocation theory using the preliminary reference earth model and our formulas we calculate coseismic changes in earth s rotation and low degree stokes coefficients caused by the four largest earthquakes since 1960 the results verify that the present method is consistent with previous studies but the method cannot be verified by the observations a case study on the 2011 tohoku oki earthquake mw 9 0 indicates that the coseismic earth rotation change depends on the magnitude and source parameters and results show a difference between a point source and finite fault model we also investigate the effect of seawater redistribution on coseismic earth rotation change but the effect is small and can be neglected

improved source parameter constraints for five undersea earthquakes from north component of grace gravity and gravity gradient change measurements abstract the innovative processing of gravity recovery and climate experiment grace data using only the north component of gravity change and its corresponding gravity gradient changes allows the enhancement of the spatial resolution for coseismic deformation signals here we report the study of five undersea earthquakes using this technique the 2004 sumatra andaman earthquake the 2007 bengkulu earthquake the 2010 maule chile earthquake the 2011 tohoku earthquake and the 2012 indian ocean earthquakes by using the high spherical harmonic degree up to degree 96 data products and the associated grace data processing techniques the retrieved north component of gravity change is up to 34 1 4 gal for the 2004 sumatra andaman earthquake which illustrates by far the highest amplitude of the coseismic signal retrieved from satellite gravimetry among previous studies we creatively apply the localized spectral analysis as an efficient method to empirically determine the practical spherical harmonic truncation degree by combining least squares adjustment with the simulated annealing algorithm point source parameters are estimated which demonstrates the unique constraint on source model from grace data compared to other data sources for the 2004 sumatra andaman earthquake grace data produce a shallower centroid depth 9 1 km as compared to the depth 28 3 km from gps data for the 2011 tohoku earthquake the grace estimated centroid location is southwest of the gps seismic solutions and the slip orientation is about 10 clockwise from the published gps seismic slip models we concluded that these differences demonstrate the additional and critical offshore constraint by grace on source parameters as compared to gps seismic data

study on co seismic energy losses from hypocenter to ocean bottom for sumatra earthquake 2004 using 3 d crustal deformation model our co seismic grace gravity data level 2 rl 05 data product gx og 2 gsm for sumatra earthquake 2004 is obtained by differencing monthly gravity field average for november 2004 from that of january 2005 and band pass filtering 17 30 degrees and orders in spectral domain here we propose an 11 layered 3 d thrust fault gravity model based on several co seismic rupture models in literature previously we have covered the 3 d modelling details and its inferences like slip rate seismic moment momentum etc in our published literature further we extend the inferences through our model for this case study here we have estimated the layer wise energy distribution by undertaking two types energy loss one is spherical spreading and second absorption with constrained by literature we have computed layer wise energy loss equivalent energy differential pressure slip rate ultimate slip and work done the computed differential pressure and work done for sumatra earthquake 2004 are 1 7552 108 n m2 and 1 657 1018 j respectively we also estimated the absorption coefficient calculated absorption coefficients from our model to honour the slip rate of sumatra earthquake 2004 the differential pressure is estimated for ocean bottom and sea level surface the volumetric analysis is also provided for entire 3 d body layer wise using excess mass of our model the computed differential pressure indeed corresponds to an area pulse at ocean bottom that led to a tsunami generation

ocean contribution to seismic gravity changes the sea level equation for seismic perturbations revisited during megathrust earthquakes great ruptures are accompanied by large scale mass redistribution inside the solid earth and by ocean mass redistribution due to bathymetry changes these large scale mass displacements can be detected using the monthly gravity maps of the grace satellite mission in recent years it has become increasingly common to use the long wavelength changes in the earth s gravity field observed by grace to infer seismic source properties for large megathrust earthquakes an important advantage of space gravimetry is that it is independent from the availability of land for its measurements this is relevant for observation of megathrust earthquakes which occur mostly offshore such as the mw 9 2004 sumatra andaman 2010 maule chile and 2011 tohoku oki japan events in broerse et al we examined the effect of the presence of an ocean above the rupture on long wavelength gravity changes and showed it to be of the first order here we revisit the implementation of an ocean layer through the sea level equation and compare the results with approximated methods that have been used in the literature one of the simplifications usually lies in the assumption of a globally uniform ocean layer we show that especially in the case of the 2010 maule earthquake due to the closeness of the south american continent the uniform ocean assumption is not valid and causes errors up to 57 per cent for modelled peak geoid height changes expressed at a spherical harmonic truncation degree of 40 in addition we show that when a large amount of slip occurs close to the trench horizontal motions of the ocean floor play a mayor role in the ocean contribution to gravity changes using a slip model of the 2011 tohoku oki earthquake that places the majority of slip close to the surface the peak value in geoid height change increases by 50 per cent due to horizontal ocean floor motion furthermore we test the influence of the maximum spherical harmonic degree at which the sea level equation is performed for sea level changes occurring along coastlines which shows to be important for relative sea level changes occurring along the shore finally we demonstrate that ocean floor loading self gravitation of water and conservation of water mass are of second order importance for coseismic gravity changes when grace observations are used to determine earthquake parameters such as seismic moment or source depth the uniform ocean layer method introduces large biases depending on the location of the rupture with respect to the continent the same holds for interpreting shallow slip when horizontal motions are not properly accounted for in the ocean contribution in both cases the depth at which slip occurs will be underestimated

the coseismic slip distribution of a shallow subduction fault constrained by prior information the example of 2011 tohoku mw 9 0 megathrust earthquake

gravitational seismology retrieving centroid moment tensor solution of the 2011 tohoku earthquake 1 mass rearrangement within the crust and lithospheric mantle and ocean water redistribution caused by great earthquakes are made visible by their coseismic gravity signature nowadays detectable by the gravity recovery and climate experiment grace space mission here we present a novel procedure for estimating the principal seismic source parameters hypocenter and moment tensor that relies solely on space gravity data from grace applied for the first time to the 2011 tohoku earthquake it yields a seismic source model that is consistent with a thrust earthquake and geological information of the subduction zone it closely resembles the global centroid moment tensor project solution based on the teleseismic wave inversion although the moment magnitude is higher 9 13 0 11 compared to 9 08 and the hypocenter is further offshore by about 40 km within the oceanic plate this procedure will become an important tool in seismology as it complements centroid moment tensor analysis by exploiting the new gravity data from grace

contribution of satellite gravimetry to understanding seismic source processes of the 2011 tohoku oki earthquake 1 the 2011 great tohoku oki earthquake apart from shaking the ground perturbed the motions of satellites orbiting some hundreds km away above the ground such as grace due to coseismic change in the gravity field significant changes in inter satellite distance were observed after the earthquake these unconventional satellite measurements were inverted to examine the earthquake source processes from a radically different perspective that complements the analyses of seismic and geodetic ground recordings we found the average slip located up dip of the hypocenter but within the lower crust as characterized by a limited range of bulk and shear moduli the grace data constrained a group of earthquake source parameters that yield increasing dip 7 16 2 and simultaneously decreasing moment magnitude 9 17 9 02 0 04 with increasing source depth 15 24 km the grace solution includes the cumulative moment released over a month and demonstrates a unique view of the long wavelength gravimetric response to all mass redistribution processes associated with the dynamic rupture and short term postseismic mechanisms to improve our understanding of the physics of megathrusts

variation in the diagenetic response of aragonite archives to hydrothermal alteration abstract diagenesis of carbonate minerals is ubiquitous throughout the geologic record alteration is initiated immediately after deposition or takes place in the endo and exoskeletons as early as during the lifetime of a given carbonate secreting biota and can continue throughout the burial history of carbonate sediments and rocks variations in the diagenetic response of carbonate archives pose challenges for the reconstruction of past environmental conditions based on proxy data this paper comparatively assesses alteration features of different aragonitic materials by experimentally induced diagenesis a multitude of factors lead to different reactivity and responses of a given aragonite archive and provide insight to the interpretation of diagenetically altered material in the rock record chosen materials used in this study include relatively organic rich samples such as coral skeletons and bivalve shells and organic lean abiotic carbonates such as speleothems and aragonite single crystals obtained datasets include distributions of elements organics carbon and oxygen isotope ratios and crystallographic features observed variations in diagenetic responses include mineralogy of the diagenetic phases rate and extent of mineral transformation distribution of foreign ions in the crystal lattice primarily sr mg and s and the number of specific processes and products along diagenetic pathways alteration is shown to be primarily controlled by the initial diagenetic susceptibility of the sample including porosimetry and structural characteristics concentrations of organic material and primary amounts of trace elements in the carbonate such as mg structural characteristics lead to initial internally fluid or rock buffered conditions with low porosity and permeability resulting in a greater effect of internal fluids and organics differences in the amount of organic content and internal fluids affect transformation rates secondary mineralogy and isotope equilibria samples with relatively high porosity high mineral transformation rates and high primary mg ca may preferentially form secondary aragonite during fast equilibration with the diagenetic environment our results suggest that the degree and nature of diagenetic alteration of aragonite materials are strongly controlled by the micro to nano scale internal architecture governing the availability and transfer of aqueous fluids results of this study provide significant implications for the interpretation of diagenetic signals in carbonate archives and have direct significance for the mechanistic understanding of carbonate diagenesis and paleo environmental conditions

geodetic observations detecting coseismic displacements and gravity changes caused by the mw 9 0 tohoku oki earthquake 1 this paper reports coseismic displacements and gravity changes caused by the tohoku oki earthquake mw 9 0 as observed respectively using gps in japan and china and its surrounding area and as observed by grace to interpret geodetic observation data we must choose a reasonable model among the slip models presented for the event for this purpose we first calculated the displacements using three slip models from usgs ucsb and aria respectively with different dislocation theories then we compared the results with the displacements observed in japan and china results show that the modeled coseismic displacements calculated using the slip model of wei et al aria and the spherically layered dislocation theory under the prem model agree well with the observed ones indicating that the earth s layer structural and curvature effects should be considered then we computed the coseismic geoid and gravity changes on the earth surface and at a space fixed point using the three slip models and the spherically layered dislocation theory results show that the maximum coseismic geoid change reaches 2 5 cm and that the coseismic gravity changes are about 1000 600 gal for a solid earth furthermore we processed grace data to extract coseismic changes with decorrelation and a gaussian filter of 350 km the gravity changes observed by grace were dominated by a decrease over the back arc region with 5 gal reflecting coseismic crustal dilatation of the landward plate which agrees well with the theoretically modeled values from the three finite fault models after the 2004 sumatra andaman and 2010 central chile maule earthquakes this study presents the third case of clear detection of coseismic gravity changes by grace

preceding coseismic and postseismic slips of the 2011 tohoku earthquake japan 1 we estimated the spatial and temporal evolution of the preceding aseismic slip from january 2003 to january 2011 the coseismic slip of the tohoku earthquake and the postseismic slip after the earthquake based on global positioning system gps data time dependent analysis indicates aseismic slip offshore of miyagi and fukushima prefectures from 2004 associated with a series of subduction earthquakes that overlap the aseismic slip area these preceding aseismic and coseismic slip areas are centered between the centers of the coseismic and afterslip areas of the tohoku earthquake offshore of miyagi prefecture while they overlap the coseismic and afterslip areas of the tohoku earthquake off fukushima prefecture the timing of moment magnitude nine mw9 class earthquakes appears to be controlled by multiple preceding slip events smaller earthquakes and their afterslip the preceding aseismic and coseismic slip decreased the coupling rate off the tohoku coast suggesting the possibility that the preceding slip represented a precursive stage of the tohoku earthquake the afterslip of the tohoku earthquake occurred in an area where the coseismic slip was not large complementing the large coseismic slip zone the afterslip along iwate miyagi extends up to 80 km in depth and is currently the sole mechanism of strain release in this depth range the source region of the anticipated miyagi oki earthquake shows small postseismic slip after the tohoku earthquake reflecting the energy release at the time of the earthquake aftershock activity is roughly governed by an afterslip process

broadscale postseismic gravity change following the 2011 tohoku oki earthquake and implication for deformation by viscoelastic relaxation and afterslip the analysis of grace gravity data revealed postseismic gravity increase by 6 gal over a 500 km scale within a couple of years after the 2011 tohoku oki earthquake which is nearly 40 50 of the coseismic gravity change it originates mostly from changes in the isotropic component corresponding to the mrr moment tensor element the exponential decay with rapid change in a year and gradual change afterward is a characteristic temporal pattern both viscoelastic relaxation and afterslip models produce reasonable agreement with the grace free air gravity observation while their bouguer gravity patterns and seafloor vertical deformations are distinctly different the postseismic gravity variation is best modeled by the biviscous relaxation with a transient and steady state viscosity of 1018 and 1019 pa s respectively for the asthenosphere our calculated higher resolution viscoelastic relaxation model underlying the partially ruptured elastic lithosphere yields the localized postseismic subsidence above the hypocenter reported from the gps acoustic seafloor surveying

seismic structure and seismogenesis off sanriku region northeastern japan summary in 1997 a seismic experiment using an airgun array and ocean bottom seismographs obss was performed in the forearc region of the northeastern japan nej arc the objectives of this experiment were to clarify seismic structures of the forearc region off sanriku japan using airgun obs data and to understand the nature of the japan trench seismogenic zone fundamental features of the structure are as follows i the subduction angle becomes steeper from east to west from 3 to 8 to 11 with the top of the plate located at depths of 11 km 40 km west from the trench 21 km 120 km west from the trench and 28 km 140 km west from the trench respectively ii the nej moho beneath the forearc is defined at a depth of approximately 20 km iii p wave velocity of the island arc upper mantle is approximately 8 km s 1 iv the p wave velocity of the cretaceous sedimentary layer exhibits significant lateral variability 4 0 5 5 km s 1 i nthe e w direction v the upper crust of nej forearc also has the significant lateral heterogeneity 5 0 6 3 km s 1 i nthe e w direction but not in the n s direction vi the middle crust defined on land extends in some locations 40 km east of the coastline vii lateral variability in the p wave velocity of the lower crust 6 7 7 0 km s 1 i ssmall compared with that of the upper crust according to these results it is suggested that the rupture areas of large earthquakes m7 in this region are limited within the contact zone between the nej arc crust and the subducting oceanic crust although a thin layer with low velocity is probably present within this contact zone the serpentinization of uppermost mantle wedge of the nej arc by reaction between the mantle materials and the water from the thin layer beneath forearc region is limited this might indicate that a significant volume of water and sediments subduct with the slab to depths of over 20 km

coseismic gravity changes of the 2011 tohoku oki earthquake from satellite gravimetry 1 the massive tohoku oki earthquake of a moment magnitude mw of 9 0 occurred on 11 march 2011 off the pacific coast of the northeastern japan the mass redistribution in and around the focal region associated with this earthquake was studied using the gravity changes detected by gravity recovery and climate experiment grace satellite after the 2004 sumatra andaman and the 2010 central chile maule earthquakes the present study presents the third case of clear detection of coseismic gravity changes by grace the observed gravity changes were dominated by decrease over the back arc region of 7 gal or less this reflects to a large extent coseismic crustal dilatation of the landward plate they agree well with the changes calculated with the green s function for the realistic earth using fault parameters inferred from coseismic crustal movements the spatial patterns of the gravity changes of these earthquakes are very similar because they are all shallow angle reverse faulting at convergent plate boundaries we found linear relationship between gravity decreases and seismic moments

regional gravity decrease after the 2010 maule chile earthquake indicates large scale mass redistribution 1 we report small but detectable changes in the grace satellites relative trajectory after the m8 8 maule chile earthquake on 27 february 2010 that can be used to delineate the shift in the gravity field a gravity anomaly of 5 gal with a spatial scale of 500 km was found east of the epicenter after the earthquake based on coseismic models the long wavelength negative gravity change is primarily the result of crustal dilatation as well as surface subsidence in the onland region the offshore positive gravity anomaly predicted from finite fault coseismic models is considerably smaller because the gravity changes due to surface uplift and interior deformation are opposite in polarity our study suggests a role for large scale gravity observations in deciphering changes of the earth s interior during great earthquakes by filling in the seldom observed long wavelength spectrum of earthquake deformations as a complement to surface geodetic measurements and seismic data

severe downslope windstorm calculations in two and three spatial dimensions using anelastic interactive grid nesting a possible mechanism for gustiness abstract the clark nonhydrostatic anelastic code is extended to allow for interactive grid nesting in both two and three spatial dimensions tests are presented which investigate the accuracy of three different quadratic interpolation formulae which are used to derive boundary conditions for the fine mesh model application of the conservation condition of kurihara and others is shown to result in significant improvements in the treatment of interactive nesting a significant improvement in the solutions for interactive versus parasitic nesting is also shown in the context of forced gravity wave flow this result for the anelastic system is in agreement with the earlier results of phillips and shukla who considered the hydrostatic shallow water system of equations the interactive nesting model is applied to the simulation of the severe downslope windstorm of 11 january 1972 in boulder using both two and three spatial dimensions the three dimensional simulation results in a gustiness signature in the

surface volume and gravity changes due to significant earthquakes occurred in central italy from 2009 to 2016 we have modelled the surface volume and gravity changes caused by four seismic events three mainshocks moment magnitude mw 6 0 5 9 6 5 occurred during the last seismic period started on 2016 august 24 in central italy and the 2009 april 6 l aquila earthquake mw 6 3 our calculations start from the source parameters estimated by the inversion of the largest dataset of interferometric synthetic aperture radar insar and global positioning system observations ever managed in italy after earthquake occurrences based on the half space elastic dislocation theory the vertical displacements modelled after the 2016 events allow to infer a substantial unbalance between the subsided and uplifted volumes in particular we detected 106 106 m3 of hangingwall subsidence against 37 106 m3 of footwall uplift that accounts for 74 of the total volume mobilization from the ratio between the footwall and total deformed volumes we have computed an average fault dip of 47 in line with the values retrieved by seismological methods the total gravity variations which affected the study area are of the order of 1 gal 1 gal 10 8 ms 2 in the far field and 170 gal in the near field the area affected within a gravity change of 1 gal is 140 km long and 57 km wide parallel to the apennines mountain chain the larger contribution is given by positive variations which account for the tensional style of deformation and larger subsided area the significant gravity variations modelled from the coseismic deformations point out the need to update our knowledge about the absolute gravity field in italy carrying out extensive measurements and to align italy to the recent international standards about national gravity and height networks international association of geodesy iag report commission 2 gravity field http www iag commission2 ch 2015

grace gravity data help constraining seismic models of the 2004 sumatran earthquake 1 the analysis of gravity recovery and climate experiment grace level 2 data time series from the center for space research csr and geoforschungszentrum gfz allows us to extract a new estimate of the co seismic gravity signal due to the 2004 sumatran earthquake owing to compressible self gravitating earth models including sea level feedback in a new self consistent way and designed to compute gravitational perturbations due to volume changes separately we are able to prove that the asymmetry in the co seismic gravity pattern in which the north eastern negative anomaly is twice as large as the south western positive anomaly is not due to the previously overestimated dilatation in the crust the overestimate was due to a large dilatation localized at the fault discontinuity the gravitational effect of which is compensated by an opposite contribution from topography due to the uplifted crust after this localized dilatation is removed we instead predict compression in the footwall and dilatation in the hanging wall the overall anomaly is then mainly due to the additional gravitational effects of the ocean after water is displaced away from the uplifted crust as first indicated by de linage et al 2009 we also detail the differences between compressible and incompressible material properties by focusing on the most robust estimates from grace data consisting of the peak to peak gravity anomaly and an asymmetry coefficient that is given by the ratio of the negative gravity anomaly over the positive anomaly we show that they are quite sensitive to seismic source depths and dip angles this allows us to exploit space gravity data for the first time to help constraining centroid momentum tensor cmt source analyses of the 2004 sumatran earthquake and to conclude that the seismic moment has been released mainly in the lower crust rather than the lithospheric mantle thus grace data and cmt source analyses as well as geodetic slip distributions aided by gps complement each other for a robust inference of the seismic source of large earthquakes particular care is devoted to the spatial filtering of the gravity anomalies estimated both from observations and models to make their comparison significant

controls of seismogenic zone width and subduction velocity on interplate seismicity insights from analog and numerical models correlations between geodynamic parameters and interplate seismicity characteristics in subduction zones are generally weak due to the short instrumental record and multiparameter influences to investigate the role of subduction velocity vs and the width of the seismogenic zone w on maximum magnitude mmax seismic rate characteristic recurrence rate c and moment release rate mrr we use synthetic data sets from simplified analog and numerical models to gain insight into natural subduction zones seismicity our models suggest that mmax increases with w and is unaffected by vs increases with vs c increases with vs w and mrr increases with vs w in nature only the positive correlation between vs and is significant random sampling of our time series suggest that the positive correlation between vs and can be observed with short observation time windows other correlations including mmax versus w become clear only for time window lengths longer than 1 c

the generation and propagation of a nocturnal squall line part ii numerical simulations abstract the mechanisms behind the convective regeneration that occurred at midnight on 26 may 1985 in the kansas pre storm network described in part i are examined with a numerical cloud model three mechanisms that could have caused the regeneration are identified 1 an increase in low level moisture 2 an increase in low level shear and 3 a mesoscale oscillation forced by previous convection the first numerical experiments begin with a horizontally uniform environment a primary squall line is generated in this environment and is then allowed to decay four hours after the decay a second convective system develops at the leading edge of the gust front from the primary squall line it is shown that this secondary generation is due to a mesoscale oscillation centered at 70 kpa that is forced by the previous convective system horizontal variations in the upstream environment are then considered an increase in low level moisture is examined first and it is shown that the consequent lowering of th