coesite bearing eclogites from the dabie mountains central china petrogenesis p t paths and implications for regional tectonics coesite and kyanite bearing eclogites are abundant in the southern part of the dabie mountains southern dabie terrane sdt two types of eclogites from the sdt types iii and iv were selected for detailed paragenetic study type iii eclogites most abundant in the northern part of the sdt occur as blocks in gneisses and marble and contain eclogitic assemblages of omphacite garnet phengite epidote coesite kyanite carbonate rutile ilmenite these minerals exhibit weak compositional zoning and contain few mineral inclusions type iv eclogites mostly in the southern part of the sdt occur as coherent layers interbedded with gneisses and amphibolites and have assemblages of omphacite garnet glaucophane kyanite epidote phengite quartz rutile ilmenite garnets of type iv eclogites exhibit a prograde compositional zoning and have mineral inclusions of paragonite phengite epidote quartz and rutile in the core and omphacite barroisite and mg katophorite in the rim prograd

long period 12 sec volcanic tremor observed at usu 2000 eruption seismological detection of a deep magma plumbing system 1 from a temporal deployment of a broadband seismic network at usu volcano japan we observed long period 12 sec volcanic tremors during the first few weeks of the eruptive activity which started in the end of march 2000 the source of these long period tremors are located relatively deep at a depth of 5 km and their amplitude variation well correlates with the uplift rate of the eruption area we thus attribute these long period tremors to the flow induced vibration of a magma chamber and its outlet located around the source region of the long period tremors this may be the first seismological detection of long period 10 sec vibrations of a deep magma plumbing system

ultrahigh pressure metamorphism in the magnesite aragonite stability field evidence from two impure marbles from the dabie sulu uhpm belt two magnesite bearing impure dolomitic marbles from the dabie sulu ultrahigh pressure uhp region have been investigated to clarify if they had actually attained p t conditions outside the dolomite stability field limited by the reaction dolomite aragonite magnesite and to test their potential for recording u hp conditions in both cases the silicate mineral assemblage records conditions around the terminal amphibole breakdown reaction amphibole aragonite quartz clinopyrox ene talc which is a good geobarometer between at least 2 0 and 2 6 gpa at higher pressures the terminal breakdown of talc to clinopyroxene coesite is the last p t milestone below 4 gpa recordable by the silicate assemblage but evidence of former coesite is ambiguous the dolomite dissociation curve becomes strongly divariant in fe bearing marbles and may thus be attainable during cold subduction near the 5 ck m 1 geotherm at least one of the samples from xinyan village near taihu dabie shan preserved relicts of both magnesite and aragonite and most likely attained conditions within the aragonite magnesite stability field for the second sample from sanqingge village in the sulu terrane no certain evidence has been found in this study impure dolomitic marbles have considerable potential to preserve ultra high pressure relicts particularly massive impure marbles that have not been pervasively infiltrated by fluids during exhumation are considered to preserve high pressure relicts better than metapelites paragneisses and orthogneisses and perhaps almost as well as eclogites or metaperidotites the inconspicuous mineral assemblage clinopyroxene talc or quartz after former coesite may in fact record uhp conditions

modeling of surface deformation in volcanic areas the 1970 1972 and 1982 1984 crises of campi flegrei italy campi flegrei is a densely inhabited volcanic area within a caldera 12 14 km in diameter immediately west of naples italy in 1970 1972 and in 1982 1984 campi flegrei experienced considerable ground surface deformation producing a bulge about 3 5 m high at its peak in the two inflation episodes the point of maximum uplift did not change coinciding with the caldera center about which the displacements exhibited radial symmetry the 1982 1984 uplift was accompanied by considerable seismic activity gravity changes have been interpreted as reflecting the occurrence of a subvertical magmatic intrusion volcanological petrological and geophysical data point to the existence of a shallow magma chamber just beneath the center of the caldera we assume that the observed surface displacements are the response of an essentially elastic medium to a pressure increase in the magma chamber static deformation is calculated by using a finite element method assuming axial symmetry around a vertical axis through the caldera center the role played by various components of the model geometry boundary conditions elastic properties is analyzed it is shown that models assuming uniform elasticity are inadequate therefore the major volcanotectonic features as well as the influence of temperature and pressure on the elastic properties are taken into account the results of various more complex models are presented it is suggested that a progressively fractured zone whose size and shape depend also on the possible occurrence of magmatic intrusions may explain the observed surface displacements and the other data collected at campi flegrei it is suggested that the 1970 1972 uplift was possibly accompanied by larger scale changes in the stress field

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

satellite radar interferometry 1993 1999 suggests deep accumulation of magma near the crust mantle boundary at the krafla volcanic system iceland 1 deep magma accumulation near the crust mantle boundary 21 km depth at the krafla volcanic system is suggested from insar observations a best fit model derived from four interferograms covering 1993 1999 comprises an opening dike representing plate spreading and post rifting deformation and two mogi sources a mogi source deflating at a rate of 0 3 106 m3 yr coincides with the shallow krafla magma chamber while a deeper inflating mogi source further north at 21 km depth inflates at a rate of 26 106 m3 yr the inflating source is at or near the crust mantle boundary as identified by seismic studies and is interpreted as accumulating magma

insar observations of post rifting deformation around the dabbahu rift segment afar ethiopia summary increased displacement rates have been observed following manylarge earthquakes and mag matic events although an order of magnitude smaller than the displacements associated with the main event the post seismic or post rifting deformation may continue for years to decades after the initial earthquake or dyke intrusion due to the rare occurrence of subaerial rifting events thereareveryfewobservationstoconstrainmodelsofpost riftingdeformation in2005 september a 60 km long dyke was intruded along the dabbahu segment of the nubia arabia plate boundary afar ethiopia marking the beginning of an ongoing rifting episode con tinued activity has been monitored using satellite radar interferometry and data from global positioning system instruments deployed around the rift in response to the initial intrusion using multiple satellite passes we are able to separate the rift perpendicular and vertical displacement fields around the dabbahu segment rift perpendicular and vertical rates of up to 180 and 240 mm yr 1 respectively here we show that models of viscoelastic relaxation alone are insufficient to reproduce the observed deformation field and that a large portion of the observed signal is related to the movement of magma within the rift segment our models suggest upper mantle viscosities of 10 18 19 pas overlain by an elastic crust of between 15 and 30km to fit the observations inflation and deflation of magma chambers in the centre of the rift and to the south east of the rift axis is required at rates of 0 13 and 0 08km 3 yr 1

subsidence in the paricutin lava field causes and implications for interpretation of deformation fields at volcanoes abstract assessment of volcanic hazards includes interpretation of ground deformation signal which at polygenetic volcanoes often results from the superposition of deformation due to pressure changes in the magmatic system and due to surficial processes such as cooling of emplaced lava the deformation signal associated with emplaced lava is sometimes considered negligible if fields are decades old but if the lava thickness is great deformation may still be occurring possibly leading to misinterpretation of the observed deformation here i evaluate the 2007 2011 ground motion of the 1943 1952 lava field of the paricutin monogenetic cinder cone mexico interferometric synthetic aperture radar insar time series reveal patchy subsidence restricted to the lava field and following linear rates up to 5 5 cm year there is a clear correlation between subsidence rates and topography suggesting a causal relationship with deposits or lava thickness i estimate these thicknesses in the subsiding areas using pre and post eruption topographic maps and show that they reach up to 200 m a numerical model for lava flow cooling was developed considering radiation and convection from the surface conductive transfer inside the flow and to the ground and vesiculation and latent heat generation at the top and bottom of the flow the model shows that compaction induced by cooling of the thick deposits emplaced 60 years ago explains the observed subsidence when conductive transfer to the ground is considered these results demonstrate that thick deposits can keep deforming significantly even decades after their emplacement emphasizing the importance of considering cooling processes when interpreting deformation fields at polygenetic volcanoes producing massive lava fields

the eruptive history and magmatic evolution of aluto volcano new insights into silicic peralkaline volcanism in the ethiopian rift the silicic peralkaline volcanoes of the east african rift are some of the least studied volcanoes on earth here we bring together new constraints from fieldwork remote sensing geochronology and geochemistry to present the first detailed account of the eruptive history of aluto a restless silicic volcano located in a densely populated section of the main ethiopian rift prior to the growth of the aluto volcanic complex before 500 ka the region was characterized by a significant period of fault development and mafic fissure eruptions the earliest volcanism at aluto built up a trachytic complex over 8 km in diameter aluto then underwent large volume ignimbrite eruptions at 316 19 ka and 306 12 ka developing a 42 km2 collapse structure after a hiatus of 250 ka a phase of post caldera volcanism initiated at 55 19 ka and the most recent eruption of aluto has a radiocarbon age of 0 40 0 05 cal ka bp during this post caldera phase highly evolved peralkaline rhyolite lavas ignimbrites and pumice fall deposits have erupted from vents across the complex geochemical modelling is consistent with rhyolite genesis from protracted fractionation 80 of basalt that is compositionally similar to rift related basalts found east of the complex based on the style and volume of recent eruptions we suggest that silicic eruptions occur at an average rate of 1 per 1000 years and that future eruptions of aluto will involve explosive emplacement of localised pumice cones and effusive obsidian coulees of volumes in the range 1 100 106 m3

ultra high pressure metamorphism of carbonate rocks in the dabie mountains central china abstract widespread ultra high p assemblages including coesite quartz pseudomorphs after coesite aragonite and calcite pseudomorphs after aragonite in marble gneiss and phengite schist are present in the dabie mountains eclogite terrane these assemblages indicate that the ultra high p metamorphic event occurred on a regional scale during triassic collision between the sino korean and yangtze cratons marble in the dabie mountains is interlayered with coesite bearing eclogite and gneiss and as blocks of various size within gneiss discontinuous boudins of eclogite occur within marble layers marble contains an ultra high p assemblage of calcite aragonite dolomite clinopyroxene garnet phengite epidote rutile and quartz coesite coesite quartz pseudomorphs after coesite aragonite and calcite pseudomorphs after aragonite occur as fine grained inclusions in garnet and omphacite phengites contain about 3 6 si atoms per formula unit based on 11 oxygens similar to the coesite bearing eclogite marble exhibits retrograde recrystallization under amphibolite greenschist facies conditions generated during uplift of the ultra high p metamorphic terrane retrograde minerals are fine grained and replace coarse grained peak metamorphic phases the most typical replacements are symplectic pargasitic hornblende epidote after garnet diopside plagioclase an18 after omphacite and fibrous phlogopite after phengite ferroan pargasite plagioclase and actinolite formed along grain boundaries between garnet and calcite and calcite and quartz respectively the estimated peak p t conditions for marble are comparable to those for eclogite garnet clinopyroxene geothermometry yields temperatures of 630 760 c the garnet phengite thermometer gives somewhat lower temperatures the minimum pressure of peak metamorphism is 27 kbar based on the occurrence of coesite such estimates of ultra high p conditions are consistent with the coexistence of grossular rich garnet rutile and the high jadeite content of omphacite in marble the fluid for the peak metamorphism was calculated to have a very low xco2 0 03 the p t conditions for retrograde metamorphism were estimated to be 475 550 c at 7 kbar

3 d surface deformation of the 2000 usu eruption measured by matching of sar images a subpixel level offset estimation technique was applied to sar synthetic aperture radar images of usu volcano japan using radarsat sar amplitude images acquired from ascending and descending orbits we generated a map of three dimensional displacement vectors showing ground deformation associated with criptdome formation in april 2000 moreover displacement velocities and volume changes were estimated from april 3 29 inflation was observed with vertical and horizontal displacements each exceeding 20m during the period of major activity from april 3 5 uplift and n s spreading velocities reached 3 3m day and 2 7m day respectively while volume change was 3 4 106 m day although this technique is less precise than other methods and is not very sensitive to local deformations it provides several key advantages including 1 personnel are not required to enter hazardous areas 2 it provides wide spatial coverage and 3 it does not depend on coherence making it more widely applicable than insar

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

ultrahigh pressure metamorphism in western tianshan china part i evidence from inclusions of coesite pseudomorphs in garnet and from quartz exsolution lamellae in omphacite in eclogites inclusions of coesite pseudomorphs in garnets have been found in type i eclogites interlayered with mafic blueschists and carbonate eclogites and quartz exsolution lamellae in omphacites have been recognized in type ii eclogites with pillow structure in western tianshan china based on mineralogy and petrology the metamorphic evolution of western tianshan eclogites can be divided into three stages 1 pre peak ultrahigh pressure uhp eclogite facies stage 356 443 c 8 10 kb 2 uhp eclogite facies stage 496 598 c 25 7 26 7 1 kbar and 3 retrograde epidote blueschist facies stage 500 530 c 10 12 kbar consequently the eclogites from the western tianshan region of china have undergone unambiguous uhp metamorphism

post eruptive volcanic dome evolution as revealed by deformation and microgravity observations at usu volcano hokkaido japan abstract usu volcano hokkaido japan is a dacitic volcano known for its high production rate of lava domes and crypto domes it is thus a good target to study processes of volcanic dome evolution upheaval and or relaxation we carried out repeated gps and microgravity surveys on the three most recent domes of mt usu 1910 meiji shinzan 1943 1945 showa shinzan and 1977 1982 usu shinzan the repeat period was 1 to 2 months and extended from october 1996 to june 1997 we also compare new data with results from former studies more than 20 years after the start of usu shinzan dome growth there is still subsidence at a maximum rate of about 7 to 8 cm year the reasons for this subsidence are discussed repeated gravity surveys revealed an increase of gravity on the domes about 60 10 microgal year for usu shinzan about 15 microgal at showa shinzan and 10 to 20 microgal for meiji shinzan this gravity increase exceeds that expected due to subsidence we discuss and interpret the excess gravity change in terms of a density increase in the edifice caused by a combination of processes contraction of the edifice water level change devesiculisation cooling and magma intrusion quantification of these processes at usu volcano may help to understand the processes of evolution at domes on other volcanoes such as merapi indonesia unzen japan or montserrat west indies

post emplacement cooling and contraction of lava flows insar observations and a thermal model for lava fields at hekla volcano iceland lava flows contract as they cool causing progressive subsidence of the flow surface here we study this process by measuring and modelling the deformation of emplaced lava flows and the surrounding substrate the temporal trend of vertical lava movements was investigated using interferometric analysis of synthetic aperture radar insar images from the 1991 and 2000 hekla eruptions covering periods of 23 and 12 years respectively data from six tracks from three satellites including both ascending and descending passes were used to create 99 interferograms from which trends of accumulated subsidence and subsidence velocities were derived subsidence rates are similar for both lava flows and decay approximately exponentially from about 20 mm year five years after emplacement to about 2 mm year 15 years after emplacement a one dimensional semi analytical model was fitted to the observed subsidence rates with subsidence due to phase change calculated analytically and subsidence due to thermal contraction calculated numerically using dilatometic constraints obtained experimentally the initial thicknesses of the 1991 and 2000 lava fields d1991 and d2000 scaled thermal expansivity and thermal diffusivity are the crucial parameters influencing lava subsidence and subsidence rate inversion for these parameters reveal linear correlations between them best fitting results of inversions for d1991 range from 10 m to 27 m for d2000 from 10 m to 30 m 9 24 10 6k 1 and 1 7 10 7m2s 1

green ampt infiltration parameters from soils data the analysis of approx 5 000 soil horizons indicated that green and ampt parameters effective porosity wetting front capillary pressure and hydraulic conductivity could not be developed based on phases of soil order or suborder however sets of average parameters are developed based on soil horizon or soil texture class or both a procedure for determining the green and ampt parameters based on soil properties utilizing the full spectrum of soil survey information is outlined

carbon recycled into deep earth evidence from dolomite dissociation in subduction zone rocks comment and reply reply i appreciate the interest that hermann has shown in our study of carbon recycled into deep earth zhu and ogasawara 2002a 1 the work reported in that paper was accomplished in ogasawara s laboratory at waseda university all samples were collected by ogasawara and the first author

the effects of topography on magma chamber deformation models application to mt etna and radar interferometry we have used a three dimensional elastic finite element model to examine the effects of topography on the surface deformation predicted by models of magma chamber deflation we used the topography of mt etna to control the geometry of our model and compared the finite element results to those predicted by an analytical solution for a pressurized sphere in an elastic half space topography has a significant effect on the predicted surface deformation for both displacement profiles and synthetic interferograms not only are the predicted displacement magnitudes significantly different but also the map view patterns of displacement it is possible to match the predicted displacement magnitudes fairly well by adjusting the elevation of a reference surface however the horizontal pattern of deformation is still significantly different thus inversions based on constant elevation reference surfaces may not properly estimate the horizontal position of a magma chamber we have investigated an approach where the elevation of the reference surface varies for each computation point corresponding to topography for vertical displacements and tilts this method provides a good fit to the finite element results and thus may form the basis for an inversion scheme for radial displacements a constant reference elevation provides a better fit to the numerical results

the kokchetav massif kazakhstan type locality of diamond bearing uhp metamorphic rocks abstract after the discovery of metamorphic coesite in crustal rocks from the western alps italy and the western gneiss region norway in the mid 1980s of the last century metamorphic diamond was observed only a few years later in situ in the kokchetav massif kazakhstan findings of such coesite and diamond bearing ultrahigh pressure metamorphic uhp rocks with protoliths formed or embedded in crustal levels and subsequently experienced pt conditions within or even higher than the coesite stability field have dramatically changed our geodynamic view of orogenetic processes these occurrences provide evidence that crustal rocks were subducted into mantle depths and exhumed to the surface recent studies even suggest continental subduction to depths exceeding 300 km these rocks have been extensively studied and many new and important observations have been made thus far more than 350 papers have been published on various aspects of kokchetav uhp rocks the kokchetav massif of northern kazakhstan is part of one of the largest suture zones in central asia and contains slices of hp and uhp metamorphic rocks classical uhp rocks mainly occur in the kumdy kol barchi kol and kulet areas and include a large variety of lithologies such as calcsilicate rocks eclogite gneisses schists marbles of various compositions garnet pyroxene quartz rocks and garnet peridotite most of them contain microdiamonds some of which reach a grain size of 200 m most diamond grains show cuboid shapes but in rare cases diamonds within clinozoisite gneiss from barchi kol occur as octahhedral form microdiamonds contain highly potassic fluid inclusions as well as solid inclusions like carbonates silicates and metal sulfides which favour the idea of diamond formation from a c o h bearing fluid nitrogen isotope data and negative 13c values of kokchetav diamonds indicate a metasedimentary origin pt estimates of kokchetav uhp rocks yield peak metamorphic conditions of at least 43 kbar at temperatures of about 950 1000 c some zircon separates show inherited proterozoic cores and 537 530 ma uhp metamorphic mantle zones several ar ar ages on micas scatter around 529 528 and 521 517 ma and reflect different stages of the exhumation history migmatization occurred during exhumation at about 526 520 ma isotopic studies on calcsilicate rocks confirm a metasedimentary origin 18o values of garnet and clinopyroxene of a layered calcsilicate rock rule out the possibility having a primitive mantle protolith similar studies on eclogites indicate their basaltic protolith having experienced water rock interaction prior to uhp metamorphism a number of unique mineralogical findings have been made on kokchetav uhp rocks k feldspar exsolutions in clinopyroxene demonstrate that potassium can be incorporated into the cpx structure under upper mantle pressures other significant observations are coesite exsolutions in titanite quartz rods in cpx the discovery of k tourmaline as well as new minerals like kokchetavite a hexagonal polymorph of k feldspar and kumdykolite an orthorhombic polymorph of albite the kokchetav uhp rocks represent a unique and challenging stomping ground for geoscientists of various disciplines from crystallography petrology and geochemistry to geophysics and geodynamics geotectonics it concerns all who are interested in the diverse metamorphic processes under upper mantle conditions

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

pressure sources versus surface loads analyzing volcano deformation signal composition with an application to hekla volcano iceland the load of lava emplaced over periods of decades to centuries induces a gradual viscous response of the earth resulting in measurable deformation this effect should be considered in source model inversions for volcanic areas with large lava production and flow emplacement in small centralized regions if deformation data remain uncorrected constructive load and pressure source interference may result in an overestimate of depth and volume of a magma reservoir whereas destructive signal interference may cause these values to be underestimated in both cases the source geometry preference could be biased the ratio of horizontal and vertical displacements aids the identification of composite signals we provide a method to quantify and remove the lava load deformation signals using deformation at hekla volcano iceland as an example

estimating source parameters from deformation data with an application to the march 1997 earthquake swarm off the izu peninsula japan we have applied two monte carlo optimization techniques simulated annealing and random cost to the inversion of deformation data for fault and magma chamber geometry these techniques involve an element of randomness that permits them to escape local minima and ultimately converge to the global minimum of misfit space we have tested the monte carlo algorithms on two synthetic data sets we have also compared them to one another in terms of their efficiency and reliability we have applied the bootstrap method to estimate confidence intervals for the source parameters including the correlations inherent in the data additionally we present methods that use the information from the bootstrapping procedure to visualize the correlations between the different model parameters we have applied these techniques to gps tilt and leveling data from the march 1997 earthquake swarm off of the izu peninsula japan using the two monte carlo algorithms we have inferred two sources a dike and a fault that fit the deformation data and the patterns of seismicity and that are consistent with the regional stress field

source model for the 1997 zirkuh earthquake mw 7 2 in iran derived from jers and ers insar observations summary we present the first detailed source model of the 1997 m7 2 zirkuh earthquake that ruptured the entire abiz fault in east iran producing a 125 km long bended and segmented fault trace using sar data from the ers and jers 1 satellites we first determined a multisegment fault model for this predominately strike slip earthquake by estimating fault segment dip slip and rake values using an evolutionary optimization algorithm we then inverted the insar data for variable slip and rake in more detail along the multisegment fault plane we complement our optimization with importance sampling of the model parameter space to ensure that the derived optimum model has a high likelihood to detect correlations or trade offs between model parameters and to image the model resolution our results are in an agreement with field observations showing that this predominantly strike slip earthquake had a clear change in style of faulting along its rupture in the north we find that thrust faulting on a westerly dipping fault is accompanied with the strike slip that changes to thrust faulting on an eastward dipping fault plane in the south the centre part of the fault is vertical and has almost pure dextral strike slip the heterogeneous fault slip distribution shows two regions of low slip near significant fault step overs of the abiz fault and therefore these fault complexities appear to reduce the fault slip furthermore shallow fault slip is generally reduced with respect to slip at depth this shallow slip deficit varies along the zirkuh fault from a small deficit in the north to a much larger deficit along the central part of the fault a variation that is possibly related to different interseismic repose times

modeling long term ground deformation due to the cooling of a magma chamber case of basiluzzo island aeolian islands italy 1 we estimate the long term vertical deformation of basiluzzo island located in the volcanic arc of the aeolian islands italy by inferring the subsidence of a roman age submerged wharf dated 2000 50 years ago we model the crustal deformation that produced this displacement as a cooling magma chamber emplaced during the formation of the island this is the first attempt to model crustal deformation using the subsidence of a submerged archaeological structure nowadays the top of the wharf which can be considered an unconventional leveling benchmark is located near punta levante at an average depth of 3 20 0 10 m below actual sea level and it is still in good conservation its present location is due to combined effect of sea level rise and volcanic and tectonic activity that occurred since it was built taking into account the architectural features of the wharf and that the mean sea level rise of the mediterranean sea has been estimated as 0 45 m during the last 2000 years flemming and webb 1986 we estimate a total subsidence of 3 75 0 10 m at a rate of about 1 87 mm yr 1 anzidei et al 2002 we propose a possible mechanism for the long term subsidence which occurred on a timescale of thousands of years by considering the earth s crust as a maxwell body we assume that the magmatic source is located directly beneath basiluzzo dome and underwent progressive solidification and subsequent volume reduction since its emplacement 50 000 years ago

thermal and mechanical aspects of magma emplacement in giant dike swarms we consider the thermal history and dynamics of magma emplacement in giant feeder dikes associated with continental flood basalts for driving pressure gradients inferred for giant dike swarms thicknesses of 10 m would enable dikes to transport magma laterally over the distances observed in the field up to thousands of kilometers without suffering thermal lock up using time dependent numerical solutions for the thermal evolution of a dike channel under laminar and turbulent flow conditions in the presence of phase transitions we investigate the possibility that the observed dike thicknesses of the order of 100 m result from thermal erosion of the country rocks during dike emplacement this implies that the observed range of dike widths in giant dike swarms may reflect variations in the source volume and not the excess magma pressure it is found that the total volume of intruded magma required to produce an order of magnitude increase in dike width via wall rock melting broadly agrees with the estimated volumes of individual flows in continental flood basalts the presence of chilled margins and apparently low crustal contamination characteristics of some giant dikes may be consistent with turbulent magma flow and extensive melt back during dike emplacement in this case measurements of the anisotropy of magnetic susceptibility most likely indicate magma flow directions during the final stages of dike intrusion shear stresses generated at the dike wall when the dike starts to freeze strongly decrease with increasing dike width which implies that thicker dikes may have less tendency to produce consistent fabric alignment our results suggest that if the dike was propagating downslope off a plume related topographic swell the mechanism responsible for flow termination could possibly have been related to underpressurization and collapse implosion of the shallow magma plumbing system feeding the intrusion radial dikes that erupted at the periphery of the topographic uplift might have increased rather than decreased extensional stresses in the crust within the topographic uplift upon their solidification

in situ x ray observation of the reaction dolomite aragonite magnesite at 900 1300 k to determine the reaction boundary dolomite aragonite magnesite in situ x ray experiments on dolomite decomposition and synthesis were carried out in the temperature range 900 to 1300 k dolomite decomposition experiments were conducted with increasing pressure at constant temperature and the boundary was determined to be 5 3 5 9 gpa in the temperature range 800 1200 k and 5 9 6 3 gpa at 1300 k dolomite synthesis experiments were carried out with decreasing pressure at constant temperature or with increasing temperature at constant press load the dolomite synthesis boundary was determined to be 6 7 6 9 gpa at 1300 k 3 7 4 4 gpa at 1100 k and 2 3 gpa at 800 k except at 1300k the synthesis boundary is much lower in pressure and has a steeper d p d t slope than the decomposition boundary the difference in the reaction boundary reflects the different kinetics between decomposition and synthesis reactions and the former may be closer to the equilibrium phase boundary the experimental results show that the phase boundary between dolomite and aragonite magnesite is located at 6 4 gpa at 1300 k and has a d p d t slope of 0 001 0 001 gpa k in the temperature range 900 to 1200 k

magma prospecting in usu volcano hokkaido japan using magnetotelluric soundings abstract we carried out magnetotelluric mt soundings across usu volcano hokkaido japan which has been active since 1663 the objective was to image an intrusion expected below the formation of 180m high cryptodomes formed during the 1977 78 eruption a ne sw two dimensional resistivity model has been obtained from the inversion in the frequency range from 0 01 to 10 000 hz the major features of the resistivity section are as follows 1 a 50 m thick surficial resistive 1000 10 000 m layer corresponding to the lava layer 2 a relatively conductive 10 1000 m layer from the surface to 200 m depth corresponding to quaternary sedimentary and volcanic rocks 3 beneath the quaternary formations a thick 2 4 km conductive 1 500 m layer of altered tertiary volcanics distributed widely in the volcanic edifice 4 a resistive block 500 1 000 m in the tertiary layer from 200 to 400 m in depth beneath the summit crater forming a striking contrast to the rest of the conductive tertiary layer and probably indicating a cooling intrusion at shallow depth 5 pre tertiary formations consisting of a high resistivity 1000 10 000 m layer overlying a conductive layer with the top of the pre tertiary becoming shallow to the northeast and 6 no deep conductive anomalies corresponding to a magma chamber inferred from petrological studies

quasi static thermoelastic deformation in an elastic half space theory and application to insar observations at izu oshima volcano japan summary we derive closed analytical solutions for quasi static thermoelastic deformation in response to instantaneous point and spherical heat sources in an elastic half space since we can take advantage of the solutions for an infinite medium the derivation of solutions for a semi infinite medium is straightforward we examine the spatial and temporal evolution of thermoelastic deformation for point and spherical heat sources we applied the solution to a radar interferometric observation of post eruptive deformation associated with the 1986 fissure eruption at izu oshima volcano japan assuming a spherical heat source at a depth of 240 m with a volume of 1 15 10 7 m 3 and a temperature step 10 3 k the predicted rate of post eruptive ground movement agrees with the observed rate within observational errors also the same parameter values allow us to compute the co eruptive ground displacement by the effect of mass intrusion whose amplitude is consistent with the observed height 45 m of the newly formed cone the derived solutions can be applied to transient ground displacements observed at active volcanoes and allow us to evaluate the heat amount of magma intruded at very shallow depths

inter eruptive volcanism at usu volcano micro earthquakes and dome subsidence abstract post eruptive crustal activity after the 2000 eruption of usu volcano was investigated by seismic and geodetic field observations remarkable features of the magmatic eruptions that occur almost every 30 years include lava dome formation and strong precursory earthquakes on the other hand rapid dome subsidence was observed by electronic distance meter edm measurement after the 1977 1982 summit eruption since the 2000 eruption seismic activity at a shallow part under the summit crater has remained at a high level relative to that after the 1977 1982 eruption although eruption occurred at the western foot of the volcano during the 2000 eruption to reveal the shallow crustal activity in the inter eruptive period around the summit area seismicity and crustal deformation have been investigated since 2006 dense temporary seismic observations and hypocenter relocation analysis using a three dimensional velocity structure model revealed that the focal area is localized along the u shaped fault that developed in the dome forming stage of the 1977 1982 eruption three major focal clusters are distributed on the southwestern side of usu shinzan cryptodome which was built up during the 1977 1982 eruption for the seven major events with magnitudes larger than 1 the focal mechanism was a large dip slip component which suggests the subsidence of usu shinzan cryptodome interferomatetric satellite aperture radar insar image analysis and repeated gps measurements revealed subsidence of the summit dome which is almost centered at the usu shinzan cryptodome the area of rapid deformation is restricted to a small area around the summit crater the estimated rate of dome subsidence relative to the crater floor is about 3 cm year these results strongly suggest that subsidence of usu shinzan is associated with the small earthquakes along the u shaped fault that surrounds the cryptodome according to prior seismic and geodetic studies it is thought that most of the magma rising under the summit crater during the 2000 eruption stopped around a depth of 2 km below sea level which is sufficiently deep relative to the focal area of the present seismicity a part of the magma intruded under the western foot and contributed to the 2000 eruption we conclude that the 2000 eruption scarcely affected the shallow crustal activity under the summit crater and that usu shinzan cryptodome is continuing to subside just as it was before the 2000 eruption the shallow volcanic earthquakes that began increasing from 1995 are closely related to the successive subsidence of the summit domes temporal change in fumarole temperature suggests a relationship between the shallow earthquakes and cooling of the magma that intruded under usu shinzan during the 1977 1982 eruption

thermomechanics of shallow magma chamber pressurization implications for the assessment of ground deformation data at active volcanoes abstract in this study we utilize thermomechanical models to investigate how magma chambers overpressurize as the result of either magmatic recharge or volatile exsolution by implementing an adaptive reservoir boundary condition we are able to track how overpressure dissipates as the magma chamber expands to accommodate internal volume changes we find that the size of the reservoir greatly impacts the resultant magma chamber overpressure in particular overpressure estimates for small to moderate sized reservoirs 1 10 km 3 are up to 70 lower than previous analytical predictions we apply our models to santorini volcano in greece where recent seismic activity and ground deformation observations suggested the potential for eruption the incorporation of an adaptive boundary condition reproduces mogi flux estimates and suggests that the magma reservoir present at santorini may be quite large furthermore model results suggest that if the magma chamber is 100 km 3 overpressures generated due to the high magma flux may not exceed the strength of the host rock thus requiring an additional triggering mechanism for eruption although the adaptive boundary condition approach does not calculate the internal evolution of the magma reservoir it represents a fundamental step forward from elastic mogi models and fixed boundary solutions on which future investigations of the evolution of the magma can be built

green and ampt infiltration into soils of variable pore size with depth most expressions for infiltration rely upon the assumption of vertical uniformity in soil texture and hydraulic properties we present an extension of the results of beven 1982 1984 for infiltration and lateral flow in soils with decreasing permeability with depth unlike beven we base the derivations upon joint changes in soil properties based on an overall change in characteristic pore size via miller scaling a set of very simple expressions for the time rate of infiltration are obtained using a green and ampt approach for soils with permeability that decreases with depth following linear power law and exponential relationships

experimental determination of the reaction aragonite magnesite dolomite at 5 to 9 gpa martinez et al bracketed the decomposition reaction of dolomite to aragonite magnesite between 5 0 and 5 5 gpa at 600 c using in situ xrd in a multi anvil apparatus they then extrapolated their results using the available thermodynamic data such that the breakdown reaction occurs at 1 000 c at 6 gpa if correct this extrapolation has implications for the type s of stable carbonate s in the mantle for example the reaction magnesite diopside dolomite enstatite would be metastable at p 7 gpa relative to the aragonite containing analog and thus aragonite rather than dolomite might be stable near the solidus of lherzolite this extrapolation would also imply that aragonite and magnesite would be stable in garnet clinopyroxene assemblages at pressures in the stability field of diamond to test this extrapolation experiments were conducted at higher temperatures in a multiple anvil apparatus results of initial experiments were consistent with the results of martinez et al at higher temperatures however the reaction occurs at higher pressures than predicted by martinez et al requiring significant curvature to the reaction boundary this curvature increasing dp dt with increasing t is consistent with increasing disorder in the dolomite with increasing temperature increasing the stability of dolomite relative to aragonite plus magnesite the experimental results restrict aragonite magnesite bearing assemblages to low temperature aragonite will not be present in near solidus lherzolite and can be present in orthopyroxene free eclogites and pyroxenites only at low temperature

the mineralogy of the kokchetav lamproite implications for the magma evolution abstract kokchetav lamproite occurs in the east end of kokchetav massif and consists of phenocryst mainly clinopyroxene and matrix mainly feldspar the compositions of clinopyroxene magnetite and biotite phenocryst were determined using wavelength dispersive spectrometry on a jeol super probe 8900 electron microprobe for the purpose of revealing the process of magma evolution analyses revealed a core rim variation which is consistent with three stages of magmatic evolution mg rich clinopyroxene cores diopside and biotite cores phlogopite crystallized in a deep magma chamber stage i fe rich clinopyroxene rim salite and biotite rim crystallized at low pressure in a shallow magma chamber stage ii magnetite phenocryst core also crystallized in a shallow magma chamber and co exists with fe rich clinopyroxene rim and biotite rim the magnetite rims probably formed during magma eruption at the same time when groundmass crystallized stage iii the calculated temperatures for ilmenite magnetite pair range from 679 to 887 c log f o 2 values range from 11 1 to 14 9 log units these values represent the latest conditions of magma as ilmenite exsolution in magnetite probably occurred during magma eruption from the shallow chamber to surface

temperature dependent viscoelastic modeling of ground deformation application to etna volcano during the 1993 1997 inflation period abstract we used the finite element method fem for modeling time dependent ground deformation due to volcanic pressure sources embedded in a viscoelastic medium especially in volcanic areas the presence of heterogeneous materials and high temperatures produce a lower effective viscosity of the earth s crust that calls for considering the thermal regime of crustal volume surrounding the magmatic sources we propose a thermo mechanical numerical model for evaluating the temperature dependency of the viscoelastic solution both temperature distributions and ground deformation are evaluated by solving an axi symmetric problem to estimate the effects of thermo viscoelastic response of the medium the thermo mechanical model permits to evidence that viscoelastic relaxation is responsible for significant time dependent variations in long term deformation these effects may be relevant for the interpretation and quantitative assessments of the pressure changes within magmatic sources with this in mind we reviewed the ground deformation observed on etna volcano during the 1993 1997 inflation period by setting up a fully 3d temperature dependent viscoelastic model since 1993 different geodetic measurements edm gps sar and leveling data identified an inflationary phase characterized by a uniform and continuous expansion of the overall volcano edifice that was not perturbed by eruptive activity the numerical model including significant viscoelastic material and reduced crustal rigidity around the magmatic source enables to produce deformation comparable with those obtained from elastic model requiring a significantly lower pressure for a purely elastic model with the same geometry and rigidity the pressure change necessary to describe the 1993 through 1997 inflation is around 320 mpa whereas for the viscoelastic model a pressure increase of about 200 mpa is required

3d density modeling with gravity and muon radiographic observations in showa shinzan lava dome usu japan we performed three dimensional density modeling of showa shinzan lava dome usu japan by joint inversion of the gravity anomaly and recently obtained muon radiography data our multilayer emulsion muon detector significantly reduces the background noise in our measurements of the muon flux through the dome the high quality muon data enables us to more accurately reconstruct the density structure of the lava dome compared with our own previous work we find that the lava dome consists of a cylindrical column of massive lava with a diameter of 300 m and that there is no evidence of magma intrusion in the shallow part of the plateau located east of the dome

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

high pressure phase transformations of carbonates in the system caomgosio2co2 the phase behaviour of the carbonates in the system mgocaosio2co2 have been studied in a diamond anvil press employing yag laser heating from about 40 to 260 kbar at 1000 c it is already known that at the caco3mgco3 join calcite caco3 is stable only at relatively low pressures 30 kbar that aragonite caco3 is stable between 30 and 400 kbar and that magnesite mgco3 is stable between 7 and 550 kbar at 1000 c in the present study it has been found that the intermediate mineral dolomite caco3 mgco3 decomposes into the mixture aragonite magnesite in the pressure range 60 70 kbar at 1000 c another intermediate mineral huntite caco3 3mgco3 transforms to a new phase at pressures below 40 kbar and then decomposes to the mixture dolomite magnesite at pressures greater than 60 kbar the new phase with the huntite composition possesses an orthorhombic cell with ao 9 933 0 002 bo 6 712 0 001 and co 24 06 0 02 a at ambient conditions there are only two well known silicate carbonate minerals in the caosio2co2 system these are spurrite and tilleyite both were found to decompose into their component silicates and carbonates at pressures below 40 kbar at 1000 c on the basis of the present study it can be concluded that aragonite and magnesite are the only two carbonates in the entire caomgosio2co2 system which are stable at pressures greater than about 70 kbar at 1000 c if no interaction occurs between carbonates and silicates at still higher pressures

fault slip distribution of the 1999 mw 7 1 hector mine california earthquake estimated from satellite radar and gps measurements we use a combination of satellite radar and gps data to estimate the slip distribution of the 1999 m w 7 1 hector mine earthquake a right lateral strikeslip earthquake that occurred on a northwest southeast striking fault in the southern california mojave desert the data include synthetic aperture radar interferograms insar from both ascending and descending orbits radar amplitude image offset fields sario for both ascending and descending azimuth directions and campaign gps observations from 55 stations provided by agnew et al 2002 we model the fault with nine segments derived from the field mapped fault rupture the sario data and aftershock locations we first estimate the dip of each fault segment as well as a single constant strike slip component across each segment resulting in an average dip of 83 to the northeast and slip of up to 5 6 m then we fix the optimal fault segment dip discretize the fault segments into 1 5 km 1 5 km patches and solve for the variable slip distribution using a nonnegative least squares method that includes an appropriate degree of smoothing our preferred solution has both right lateral strike slip and reverse faulting the estimated geodetic moment is 5 93 10 19 n m m w 7 1 similar to seismological estimates indicating that there are insignificant interseismic and postseismic deformation signals in the data we find strike slip displacements of up to 6 0 m and reverse faulting of up to 1 6 m with the maximum slip located just northwest of the epicenter most of the slip is concentrated northwest and south of the epicenter little slip is found on the northeastern branch of the fault the sario data and our modeling indicate that the amount and extent of surface fault rupture were underestimated in the field

a process based transfer function approach to model tile drain hydrographs tile drain response to rainfall events is determined by unsaturated vertical flow to the water table followed by horizontal saturated water movement in this study unsaturated vertical movement from the redistribution of water is modelled using a sharp front approximation and the saturated horizontal flow is modelled by an approximate solution to the boussinesq equation the unsaturated flow component models the fast response that is associated with the presence of preferential flow paths by convoluting the responses of the two components a transfer function is developed that predicts tile drain response to unit amounts of infiltrated water it is observed that the unsaturated flow component can be cast in a form that is linear in a power function of the infiltrated depth since the approach is process based model parameter definitions are easily identified with soil properties at the field scale furthermore it is demonstrated that the transfer function model parameters can be estimated from moment analysis using superposition the transient tile drain response to arbitrary amounts of infiltrated water can be constructed comparison with data measured from the water quality field station show that this approach provides a promising method for generating tile drain response to rainfall events copyright 2006 john wiley sons ltd

seismological significance of the 1977 1978 eruptions and the magma intrusion process of usu volcano hokkaido abstract an earthquake swarm and the major pumice eruptions in august 1977 which followed marked the start of the dacitic doming activity of usu volcano in southwestern hokkaido japan the sequence of magma intrusion processes was investigated in detail by means of seismological and other geophysical data the distribution of the abundant hypocenters shows clearly an earthquake free zone beneath the summit crater the hypocenters migrated in a manner consistent with the development of the observed asymmetrical surface deformations considered due to magma intrusion into this earthquake free zone the earthquake mechanism solutions are mostly of dip slip type and are interpreted in terms of the doming deformations the existence of earthquake families earthquakes with similar waveforms is the main cause of the peculiar occurrence of earthquakes in space time and magnitude the concept of scattered barriers of different sizes and strengths can explain well the distinct characteristics of the occurrence of the swarm and the observed episodic deformations

surface deformation of long valley caldera and mono basin california investigated with the sbas insar approach abstract we investigate the surface deformation of the eastern california area that includes long valley caldera and mono basin we apply the sar interferometry insar algorithm referred to as small baseline subset sbas approach that allows us to generate mean deformation velocity maps and displacement time series for the investigated area the results presented in this work represent an advancement of previous insar studies of the area that are mostly focused on the deformation affecting the caldera in particular the proposed analysis is based on 21 sar data acquired by the ers 1 2 sensors during the 1992 2000 time interval and demonstrates the capability of the sbas procedure to identify and analyze displacement patterns at different spatial scales for the overall area spanning approximately 5000 km2 two previously unreported localized deformation effects have been detected at paoha island located within the mono lake and in the mcgee creek area within the sierra nevada mountains a zone to the south of the long valley caldera in addition a spatially extended uplift effect which strongly affects the caldera has been identified and analyzed in detail the insar results clearly show that the displacement phenomena affecting the long valley caldera have a maximum in correspondence of the resurgent dome and are characterized by the sequence of three different effects a 1992 1997 uplift background a 1997 1998 unrest phenomenon and a 1998 2000 subsidence phase moreover the analysis of the retrieved displacement time series allows us to map the extent of the zone with a temporal deformation behavior highly correlated with the detected three phases deformation pattern background uplift unrest subsidence we show that the mapped area clearly extends outside the northern part of the caldera slopes accordingly we suggest that future inversion models take this new evidence into account the final discussion is dedicated to a comparison between the retrieved insar measurements and a set of gps and leveling data confirming the validity of the results achieved through the sbas insar analysis

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

geology and structure of diamond bearing rocks of the kokchetav massif kazakhstan abstract two crustal settings for microdiamond formation have been described from eclogite bearing metamorphic areas 1 the economic concentration of microdiamonds in metasedimentary gneisses and calc silicate rocks northern kazakhstan and 2 microdiamonds recently found in eclogite garnet pyroxenite and jadeitite from dabie shan mountain eastern china the latter occurrence is interpreted to be the product of ultra high pressure metamorphism in a mesozoic collision zone there are however a number of discrepancies between the geological structural and geochemical data for kazakhstan microdiamond deposits and an interpretation in terms of a deep subduction zone model the geodynamic setting of the kokchetav massif can be defined as a continental rise prism environment related to a passive continental margin where rifting predominated during early palaeozoic orogeny the kumdikol microdiamond province is closely associated with a tectonic melange zone involved in ductile to semi ductile shearing abundant in graphite microdiamonds of the kumdikol area have a dual setting in the rocks they appear to be included not only in refractory garnet and zircon but also in almost all rock forming minerals as biotite phlogopite diopside quartz and secondary sericite chlorite and sericite chlorite calcite aggregates after garnet pyroxene and plagioclase and in spite of softness of the host phases microdiamonds are well preserved on the other hand the ore body extends along the shear zone and high concentrations of the microdiamonds within it are distributed without any lithological control along the local s c surfaces of the main kumdikol strike slip shear zone this duality of microdiamond settings in absence of practically all ultra high pressure minerals except diamond itself weakens the interpretation of this occurrence in terms of very deep subduction and very fast uplift and exhumation during 15 10 ma according to recent geochronological data these microdiamonds could have been formed metastably under anisotropic stress conditions in fact the available data from the kumdikol province provides certain support for either metastable and stable hypothesis

analytical solutions for two dimensional groundwater flow with subsurface drainage tiles summary the tile drainage problem in an unconfined aquifer was investigated a mathematical model was established that describes two dimensional groundwater flow in an unconfined aquifer near a river with a linearized boussinesq equation time dependent sources and a sloped tile analytical solutions for groundwater level and discharge were derived and used to compare hydrologic conditions in a system with and without tile natural drainage we found that the spatial and temporal variations of groundwater level and discharge were significantly altered by the presence of drainage tile in an aquifer with tile drainage the groundwater level was lower and total groundwater discharge to the river increased compared to an aquifer with no tile application of the solutions to a synthetic case demonstrates that the analytical solutions derived can be used to quantify effect of tiles on nitrate loads in the baseflow of a river and assess the effectiveness of various conservation practices

a retrospective look at the february 1993 east rift zone intrusion at kīlauea volcano hawaii abstract the february 1993 dike intrusion in the east rift zone erz of k lauea volcano hawai i was recognized from tilt and seismic data but ground based geodetic data were too sparse to constrain the characteristics of the intrusion analysis of interferometric synthetic aperture radar insar from the japan aerospace exploration agency jaxa jers 1 satellite reveals a maximum of 30 cm of line of sight los displacement occurring near makaopuhi crater in the middle erz of k lauea we model this deformation signal as a subvertical dike using a 3d mixed boundary element method 3d mbem paired with a nonlinear inversion algorithm to find the best fit model the best fit dike is located just to the west of makaopuhi crater striking n50 w extends to within 100 m of the surface is 1 3 km in length by 4 2 km in width along strike and has a total volume of 7 4 106 m3 in addition a post intrusion interferogram from jers 1 spanning 1993 1997 was analyzed guided by previous results our model for the 4 year period consists of opening of the deep rift zones by about 0 5 m at 3 8 5 km depth beneath the southwest rift zone swrz erz and the summit a sub horizontal detachment fault is connected to the seaward side of the vertical dike like source to mimic the decollement known to exist beneath the volcano we classify the 1993 dike intrusion as a passive intrusion similar to those that occurred in 1997 and 1999 passive intrusions lack precursory inflation at k lauea s summit and the likely triggering mechanism is persistent deep rift opening combined with seaward motion of the south flank along the basal decollement passive intrusions make forecasting and hazard assessment difficult since they are not preceded by inflation nor by large increases in seismicity

a semi analytical model for transient flow to a subsurface tile drain the goal of this paper is to develop and test a semi analytical model for event based transient flow to a subsurface tile drain a sharp front theory was used to describe redistribution of infiltrated water in the vadose zone new approximate analytical solutions in terms of fourier series were sought for the boussinesq equation describing subsurface saturated flow subject to time dependent recharge both one and two term solutions of the series approximation were compared with observed tile hydrograph data from the purdue water quality field station wqfs in west lafayette indiana in general the models were able to capture the peaks of the tile drain hydrographs as well as the times to peak and the times of initial response to rainfall events the models performed particularly well for rainfall events with single burst hyetographs and in the prediction of the first hydrograph peak from multiple burst hyetographs though subsequent peaks could not be captured as well a further comparison of results from the one term model with those from hydrus 2d suggested that the one term model is adequate for estimating transient flow to a tile drain the solution developed here holds promise for extension to larger watersheds where the hydrology is governed by tile drains

energetics of calcium rich dolomite abstract the enthalpy of formation of sedimentary ca rich dolomite has been determined by oxide melt calorimetry the results show that ca rich dolomite is energetically different from well ordered stoichiometric dolomite the enthalpy of formation from calcite and magnesite becomes strongly more endothermic with increasing excess ca content this supports the idea that the substitution of ca in the mg layer of dolomite is energetically unfavorable ca rich dolomite is unstable relative to well ordered stoichiometric dolomite and calcite the enthalpy behavior for excess ca substitution in dolomite is different from that of mg substitution in calcite the enthalpy change is much larger in magnitude in dolomite and is more strongly dependent on composition differences in cation order as well as the presence of a modulated structure and low symmetry domains in ca rich dolomite cannot be discerned from the enthalpy data the findings confirm that the growth and occurrence of ca rich dolomite in sedimentary environments must be attributed to kinetic factors rather than to equilibrium

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

radar interferogram filtering for geophysical applications the use of sar interferometry is often impeded by decorrelation from thermal noise temporal change and baseline geometry power spectra of interferograms are typically the sum of a narrow band component combined with broad band noise we describe a new adaptive filtering algorithm that dramatically lowers phase noise improving both measurement accuracy and phase unwrapping while demonstrating graceful degradation in regions of pure noise the performance of the filter is demonstrated with sar data from the ers satellites over the jakobshavns glacier of greenland

experimental investigation on dolomite dissociation into aragonite magnesite up to 8 5 gpa we carried out high pressure and high temperature experiments on the composition camg co3 2 to determine the equilibrium boundary of dolomite aragonite magnesite up to 8 5 gpa and 1200 c using a 6 8 type multianvil high pressure apparatus employing a quenching technique dolomite dissociates into aragonite and magnesite under high p t conditions and the phase boundary of dissociation is described by a linear equation p gpa 1 75 0 0061t c at p 6 3 gpa and t 800 c the equilibrium boundary was established by reverse and backward experiments to grow dolomite from mixtures of caco3 and mgco3 with or without dolomite respectively this study suggests that the equilibrium line of the dolomite aragonite magnesite reaction could be very useful in addition to phase transformation of quartz coesite and graphite diamond to constrain p t conditions for the metamorphism of dolomite bearing ultrahigh pressure rocks

repressurization following eruption from a magma chamber with a viscoelastic aureole i analyze an approximate solution for spherical magma chambers radius r1 surrounded by maxwell viscoelastic shells radius r2 in elastic half spaces following a sudden decrease in pressure mass flux into the chamber is proportional to the pressure difference between a deep source and chamber p p t solutions depend on r2 r1 c m c where m c are magma and chamber compressibilities the relaxation time tr and the recharge time for the elastic system without recharge the system exhibits either post eruptive deflation or for incompressible magmas partial reinflation more generally immediate post eruptive inflation is favored by large tr and small r2 r1 with short tr and large the time for magma chamber pressure to recover increases significantly post eruptive creep increases the chamber pressure decreasing the pressure gradient driving recharge delaying pressure recovery following eruption the hoop stresses which are initially compressive relax toward the radial stress causing them to go through a local relative tension maximum the magma pressure in excess of the dike normal compression at the chamber wall can recover to pre eruptive values well before the chamber pressure or erupted mass recovers this suggests that dikes could nucleate at the chamber margin well before sufficient pressure has recovered to drive them far from the chamber for some parameters co eruptive deflation has not fully recovered when the magma overpressure relative to hoop stress in the elastic region is restored to pre eruptive values a condition assumed to be sufficient for eruption

drainage water temperature as a basis for verifying drainage runoff composition on slopes tile drainage water temperatures and discharge rates were measured in five highland watersheds of which most are underlain by acid crystalline rock one of them dehta e in the bohemo moravian highland czech republic was studied in greater detail the aim was to evaluate water temperature monitoring as a means of determining the source and pathway of drainage runoff during high flow events rapid increase in drainage discharge was accompanied by rapid change in water temperature in winter the rising limb of the hydrograph was accompanied by a decrease in temperature and the falling limb was associated with a corresponding temperature increase in summer the trends were reversed these data suggest that the water temperature changes are caused by the fastest component of drainage runoff water from a precipitation event or snowmelt which can be separated from the remainder of the hydrograph measurements of hydraulic conductivity soil moisture content soil temperature and groundwater table level indicate that the major portion of the event water causing this effect infiltrates in the watershed recharge zone where soils are permeable enters the weathered bedrock flows preferentially and rapidly down the slope along disjoint fissures in the bedrock finally emerging as ascending springs and is for the most part intercepted by the tile drainage systems copyright 2011 john wiley sons ltd

the unit response of groundwater outflow from a hillslope subsurface flow from a hillslope can be described by hydraulic groundwater theory as formulated by the boussinesq equation solution of its linear version brings out some of the essential features of this phenomenon arbitrary inputs can be accommodated by simple convolution of the sudden drawdown problem the relative magnitude of the driving mechanisms namely the streamwise pressure gradient resulting in diffusion and gravity i e slope resulting in advection can be determined by a simple dimensionless parameter

localized deformation at miyakejima volcano based on jers 1 radar interferometry 1992 1998 1 stacked radar interferograms at miyakejima volcano japan between 1992 and 1998 showed two localized significantly deforming areas with a magnitude of 4 6 mm yr in the radar line of sight one area is close to the 1983 eruption vent and using a simple closed analytical formulation the deformation is interpreted as due to a thermoelastic contraction of a formerly intruded magma the other one detected in the previous caldera is explained by a depressurization source whose depth 500 m coincides with that of a low resistivity zone interpreted as a hydrothermal reservoir also our computed co2 flux is consistent with in situ measurement data the reservoir volume is significantly less than the collapsed volume in 2000 and its depth is much shallower than the void detected prior to the collapse hence the depressurization would not directly induce the caldera collapse in 2000