a large refined catalog of earthquake relocations and focal mechanisms for the island of hawai i and its seismotectonic implications we present high quality focal mechanisms based on a refined earthquake location catalog for the island of hawai i focusing on mauna loa and k lauea volcanoes the relocation catalog is based on first arrival times and waveform data of both compressional and shear waves for about 180 000 events on and near the island of hawai i between 1986 and 2009 recorded by the seismic stations at the hawaiian volcano observatory we relocate all the earthquakes by applying ray tracing through an existing three dimensional velocity model similar event cluster analysis and a differential time relocation method the resulting location catalog represents an expansion of previous relocation studies covering a longer time period and consisting of more events with well constrained absolute locations the focal mechanisms are obtained based on the compressional wave first motion polarities and compressional to shear wave amplitude ratios by applying the hash program to the waveform cross correlation relocated earthquakes overall the good quality defined by the hash parameters focal solutions are dominated by normal faulting in our study area especially in the active ka iki and h lea seismic zones k lauea caldera is characterized by a mixture of approximately equal numbers of normal strike slip and reverse faults whereas its south flank has slightly fewer strike slip events our relocation and focal mechanism results will be useful for mapping the seismic stress and strain fields and for understanding the seismic volcanic tectonic relationships within the magmatic systems

anaerobic ammonium oxidation in deep sea sediments off the washington margin the significance of anaerobic ammonium oxidation anammox for nitrogen removal in deep continental margin sediments was studied with 15n amendments to suboxic sediments collected from 2800 3100 m water depth at eight sites in the cascadia basin eastern north pacific ocean consistent with earlier data from deep continental margin sediments pore water distributions of inorganic n indicated nh z removal from suboxic zone sediments likely due to reaction with nitrate anammox rates estimated from suboxic sediment incubations with 15n labled substrates ranged between 0 065 and 1 7 nmol n ml21 h21 wet sediment which suggested that anammox was responsible for the observed nh z removal anammox and denitrification rates derived from nh z and no pore water profiles were 32 82 mmol n m 22 d21 and 50 110 m mol nm 22 d21 respectively the average contribution of anammox to total n2 production was 40 15n amended sediment incubations to 42 flux from pore water inorganic n which does not support earlier reports that suggested that the relative importance of anammox increased with water depth and thereby should dominate over denitrification at depths greater than 1000 m

radon 222 as a tracer for mixing in the water column and benthic exchange in the southern california borderland the concentrations of222rn and226ra in the water column and in the sediments of santa barbara and san nicolas basins have been measured semi annually over the last four years approximately one third of excess radon profiles obtained in the water column in these basins can be adequately fit with a one dimensional eddy diffusion decay model exponential profiles in the center of san nicolas basin yield a vertical eddy diffusivity of 26 16 cm2 s and 3 4 1 0 cm2 s for santa barbara basin the application of a two dimensional eddy diffusion decay model to profiles obtained in the center and on the margins of san nicolas basin produces a better fit than is found using a one dimensional vertical eddy diffusivity the two dimensional model for san nicolas basin predicts a vertical eddy diffusivity of 17 cm2 s and a horizontal eddy diffusivity of 105 cm2 s these values are in reasonable agreement with those predicted from the vertical buoyancy gradient and the horizontal length scale the vertically integrated radon excess standing crop in the water column of santa barbara basin averages 53 23 atoms m2 s this is in good agreement with the flux across the sediment water interface of 60 15 atoms m2 s calculated by measuring radon emanation in the sediments as a function of depth and applying a molecular diffusion reaction model hence one dimensional molecular diffusion accurately predicts the flux of radon from the laminated santa barbara basin sediments in san nicolas basin the integrated radon excess in the water column is 376 143 atoms m2 s but the diffusive randon flux from san nicolas basin sediments averages only 190 53 atoms m2 s this descrepancy indicates that a non diffusive process probably macrofaunal irrigation supplies much of the flux of radon from san nicolas basin sediments

global gravity wave variances from aura mls characteristics and interpretation abstract the gravity wave gw resolving capabilities of 118 ghz saturated thermal radiances acquired throughout the stratosphere by the microwave limb sounder mls on the aura satellite are investigated and initial results presented because the saturated optically thick radiances resolve gw perturbations from a given altitude at different horizontal locations variances are evaluated at 12 pressure altitudes between 21 and 51 km using the 40 saturated radiances found at the bottom of each limb scan forward modeling simulations show that these variances are controlled mostly by gws with vertical wavelengths z 5 km and horizontal along track wavelengths of y 100 200 km the tilted cigar shaped three dimensional weighting functions yield highly selective responses to gws of high intrinsic frequency that propagate toward the instrument the latter property is used to infer the net meridional component of gw propagation by differencing the variances acquired from ascending a and descending d o

anatomy of an unstable volcano from insar multiple processes affecting flank instability at mt etna 1994 2008 1 volcano deformation may occur under different conditions to understand how a volcano deforms as well as relations with magmatic activity we studied mt etna in detail using interferometric synthetic aperture radar insar data from 1994 to 2008 from 1994 to 2000 the volcano inflated with a linear behavior the inflation was accompanied by eastward and westward slip on the eastern and western flanks respectively the portions proximal to the summit showed higher inflation rates whereas the distal portions showed several sectors bounded by faults in some cases behaving as rigid blocks from 2000 to 2003 the deformation became nonlinear especially on the proximal eastern and western flanks showing marked eastward and westward displacements respectively this behavior resulted from the deformation induced by the emplacement of feeder dikes during the 2001 and 2002 2003 eruptions from 2003 to 2008 the deformation approached linearity again even though the overall pattern continued to be influenced by the emplacement of the dikes from 2001 to 2002 the eastward velocity on the eastern flank showed a marked asymmetry between the faster sectors to the north and those largely inactive to the south in addition from 1994 to 2008 part of the volcano base south west and north lower slopes experienced a consistent trend of uplift on the order of 0 5 cm yr this study reveals that the flanks of etna have undergone a complex instability resulting from three main processes in the long term 103 104 years the load of the volcano is responsible for the development of a peripheral bulge in the intermediate term 101 years observed from 1994 to 2000 inflation due to the accumulation of magma induces a moderate and linear uplift and outward slip of the flanks in the short term 1 year observed from 2001 to 2002 the emplacement of feeder dikes along the ne and south rifts results in a nonlinear focused and asymmetric deformation on the eastern and western flanks deformation due to flank instability is widespread at mt etna regardless of volcanic activity and remains by far the predominant type of deformation on the volcano

a global morphology of gravity wave activity in the stratosphere revealed by the gps occultation data gps met using temperature profiles obtained by the gps met gps meteorology experiment from april 1995 to february 1997 we have extracted mesoscale temperature perturbations with vertical wavelengths ranging from 2 to 10 km and background brunt vaisala frequency squared n2 for each occultation event we can evaluate a potential energy ep which is assumed to be caused by atmospheric gravity waves the monthly mean values of ep at 15 20 km around japan showed an annual variation with an enhancement in winter which is consistent with the climatological behavior of the kinetic energy of gravity waves observed with the mu middle and upper atmosphere radar 34 9 n 136 0 e from 1985 to 1989 we have then derived the global distribution of ep at 20 30 km during northern hemisphere winter from november to february our analysis shows that the largest ep values are generally centered around the equator between 25 n and 25 s with considerable longitude variations longitudinal variations of ep at 20 30 km in a latitude range of 30 60 n are also analyzed resulting in larger ep values over the continents than over the pacific ocean using gps met data without antispoofing latitudinal variations of ep are determined in 15 45 km although large ep values are concentrated near the equator at 20 30 km ep tends to become larger at midlatitudes at 30 40 km and higher altitude regions at midlatitudes ep is found to be larger in winter months in both hemispheres height variations of ep indicate a decrease at 25 30 km and a monotonic increase above 30 km

quasi biennial and semi annual oscillations in equatorial wind fields constructed by data assimilation since october 1991 the u k meteorological office has used the technique of data assimilation to produce global meteorological analyses of the troposphere and stratosphere these analyses are constructed from conventional meteorological measurements in the troposphere and lower stratosphere and temperature soundings from noaa polar orbiting satellites the analyses show very clear quasi biennial and semi annual oscillations in equatorial winds the quasi biennial oscillation has its maximum amplitude of about 20 ms 1 near 30 hpa and exhibits descending easterly and westerly shear zones analysed winds compare well with radiosonde observations in the lower stratosphere the semi annual oscillation has its peak amplitude of about 30 ms 1 near the stratopause winds near the equatorial stratopause show strong longitudinal variations on a planetary scale during both the westerly and easterly phases of the semi annual oscillation

benthic fluxes and pore water studies from sediments of the central equatorial north pacific nutrient diagenesis benthic exchange rates of radon 222 oxygen nitrate ammonia and silica were determined using an in situ benthic flux chamber and by modeling pore water profiles at three sites in the central equatorial north pacific a comparison of these results reveals several artifacts of pore water collection and processing whole core squeezer wcs silica profiles are influenced by adsorption during squeezing and yield calculated fluxes that are too large pore water ammonia profiles show near surface maxima that appear to be an artifact of core recovery near surface nitrate measurements may also be suspect due to oxidation of the ammonia released causing anomalously large nitrate gradients that yield overestimates of benthic exchange rates fluxes of radon oxygen and nitrate calculated from wcs profiles agree with chamber fluxes to better than 40 at all sites fluxes of silica and nitrate calculated from pore water data collected at coarser scales 1 cm intervals agree within 50 with chamber measurements previous flux estimates from pore water and solid phase models established at two of these sites using data collected 6 years prior to this work differ from these chamber measurements in some cases by up to a factor of 5 due to modeling uncertainties and temporal variabilities in the delivery of organic matter to a site the benthic oxygen consumption rates measured at these sites are similar they average 0 36 0 03 mmol m 2 day 1 and are consistent with a trend of oxygen uptake vs water depth previously established by others on a transect through the oligotrophic north pacific gyre

spatiotemporal model of kīlauea s summit magmatic system inferred from insar time series and geometry free time dependent source inversion k lauea volcano hawai i island has a complex magmatic system including summit reservoirs and rift zones kinematic models of the summit reservoir have so far been limited to first order analytical solutions with pre determined geometry to explore the complex geometry and kinematics of the summit reservoir we apply a multitrack wavelet based insar interferometric synthetic aperture radar algorithm and a novel geometry free time dependent modeling scheme to map spatiotemporally distributed surface deformation signals over k lauea s summit we process sar data sets from two overlapping tracks of the envisat satellite including 100 images during the period 2003 2010 following validation against global positioning system gps data we invert the surface deformation time series to constrain the spatiotemporal evolution of the magmatic system without any prior knowledge of the source geometry the optimum model is characterized by a spheroidal and a tube like zone of volume change beneath the summit and the southwest rift zone at 2 3 km depth respectively to reduce the model dimension we apply a principal component analysis pca scheme which allows for the identification of independent reservoirs the first 3 pcs explaining 99 63 8 28 5 and 6 6 respectively of the model include six independent reservoirs with a complex interaction suggested by temporal analysis the data and model presented here in agreement with earlier studies improve the understanding of k lauea s plumbing system through enhancing the knowledge of temporally variable magma supply storage and transport beneath the summit and verify the link between summit magmatic activity seismicity and rift intrusions

a gravity wave climatology for antarctica compiled from challenging minisatellite payload global positioning system champ gps radio occultations 1 the seasonal geographical and altitudinal dependence of gravity wave activity in the lower stratosphere over antarctica is presented gravity wave activity is estimated by calculating potential energy ep from radio occultation profiles obtained by the challenging minisatellite payload global positioning system champ gps experiment significant seasonal variation of wave activity is observed smaller wave activity in summer is attributed to waves with small phase velocities experiencing critical level filtering at other times of the year when wave activity is large less filtering occurs and the strong background wind is likely to cause doppler shifting of waves to longer vertical wavelengths which can reach larger amplitudes before saturating relationships between gravity wave activity and geographic location indicate that topography is a strong source for wave activity especially over the antarctic peninsula however wind rotation in this area was found to reduce the wave energy in summer at certain altitudes a strong enhancement of wave energy is observed at the edge of the polar vortex again reduced critical level filtering and doppler shifting in the area of the jet are likely to be major causes for this finding possible limitations to this study due to observational filtering are discussed

edifice strength and magma transfer modulation at piton de la fournaise volcano 1 from 2003 to 2007 eruptive activity at piton de la fournaise was shown to follow cycles comprising many summit proximal eruptions and finishing by a distal eruption gps measurements evidenced striking asymmetric deformation between its western and eastern flanks horizontal displacements recorded during interdistal periods showed a characteristic amplitude at the top of the eastern flank displacements recorded at the base of the summit cone showed a bimodal distribution with low amplitudes during interdistal periods and large ones during distal eruptions to account for displacement asymmetry characteristic amplitude and large flank displacement we modeled the volcanic edifice using a drucker prager elastoplastic rheology friction angles of 15 and 30 were needed to model the displacements respectively during distal eruptions and interdistal periods this change shows that strain weakening occurred during distal events large plastic displacement that occurred in the eastern flank during distal eruptions relaxed the horizontal elastic stress accumulated during interdistal periods it triggered summit deflation horizontal magma transfer and distal flank eruption and reset the eruptive cycle our elastoplastic models also show that simple source geometries may induce large eastern flank displacements that would be explained by a complex geometry in a linear elastic edifice magma supply is often thought to control volcano s eruptive activity with surface deformation reflecting changes in magma supply rate the volcano s response being linear our results bring some evidences that on piton de la fournaise time space discretization of magma transfer may be the result of the edifice s nonlinear response rather than changes in magma supply

biogenic budgets of particle rain benthic remineralization and sediment accumulation in the equatorial pacific abstract budgets of organic c corg cac03 and opal have been constructed for the palisades ny pacific equatorial region at 140 w between 5 n and 5 s measurements of the rain and benthic remineralization rate of biogenic materials have been adjusted and normalized to account for sampling biases sea surface temperature serves as a master variable in normalizing sediment trap and benthic remineralization data to average conditions the rain and remineralization rates for corg are nearly equal 0 40 0 05 and 0 46 0 06 mmol m 2 d 1 respectively thus only a minor fraction of this constituent is buried rain and dissolution rates for biogenic opal are similarly balanced 0 3 0 06 and 0 36 0 01 mmol m 2 d 1 and consistent with the value for opal burial 0 0 0 004 the cac03 budget appears to have changed during the holocene the best estimates of modern cac03 dissolution 0 58 0 03 mmol m 2 d 1 and rain rate 0 61 0 06 are consistent with230th normalized carbonate accumulation rates for the late holocene 0 1 mmol m 2 d 1 however the balance between dissolution and rain is not consistent with early holocene carbonate accumulation 0 3 mmol m 2 d 1 and this imbalance suggests 1 a recent increase in the rate of cac03 dissolution on the sea floor or 2 a decrease in the rain rate of carbonate particles modeling230th profiles in sediments from this region define the last 3000 years as the duration of increased dissolution or decreased particle rain 231pa 230th ratios in sediments indicate that particle rain rates have remained constant or possibly increased slightly through the holocene two potential causes for increased dissolution were investigated a change in deep water carbonate saturation or a change in co g cac03 rain ratios a model describing carbonate dissolution as a function of the degree of undersaturation and the amount of organic carbon oxidation within sediments indicates that the recent increase in dissolution is more likely due to changes in bottom water chemical composition we propose that pacific ocean bottom water carbonate ion concentration has decreased by 10 15 m over the last 3000 years

evolution of dike opening during the march 2011 kamoamoa fissure eruption kīlauea volcano hawai i 1 the 5 9 march 2011 kamoamoa fissure eruption along the east rift zone of k lauea volcano hawai i followed months of pronounced inflation at k lauea summit we examine dike opening during and after the eruption using a comprehensive interferometric synthetic aperture radar insar data set in combination with continuous gps data we solve for distributed dike displacements using a whole k lauea model with dilating rift zones and possibly a deep decollement modeled surface dike opening increased from nearly 1 5 m to over 2 8 m from the first day to the end of the eruption in agreement with field observations of surface fracturing surface dike opening ceased following the eruption but subsurface opening in the dike continued into may 2011 dike volumes increased from 15 to 16 to 21 million cubic meters mcm after the first day eruption end and 2 months following respectively dike shape is distinctive with a main limb plunging from the surface to 2 3 km depth in the up rift direction toward k lauea s summit and a lesser projection extending in the down rift direction toward pu u at 2 km depth volume losses beneath k lauea summit 1 7 mcm and pu u 5 6 mcm crater relative to dike plus erupted volume 18 3 mcm yield a dike to source volume ratio of 2 5 that is in the range expected for compressible magma without requiring additional sources inflation of k lauea s summit in the months before the march 2011 eruption suggests that the kamoamoa eruption resulted from overpressure of the volcano s magmatic system

mls observations of atmospheric gravity waves over antarctica 1 stratospheric gravity waves over antarctica are studied with the radiance variances observed by upper atmosphere research satellite microwave limb sounder uars mls strong wave activities are found during august and september in 1992 1994 over the drake passage region 290 315 longitude and 50 s 70 s latitude where the enhancement seems associated with the topography of both south america and antarctic peninsula tips during the same period significant gravity wave activities are also evident along the antarctic coastal region the vertical growth of the wave variance shows a scale height of 14 km at low altitudes for both drake passage and the coastal regions but reduces substantially at high altitudes the growth rate transition occurs at a lower altitude in the drake passage region where the variance is larger the gravity wave activities observed near the antarctic may contribute significantly to the formation of polar stratospheric clouds psc because of the overlapping with the vortex edge and with the psc activities as observed by claes cryogenic limb array etalon spectrometer

deformation of basaltic shield volcanoes under cointrusive stress permutations we performed a microstructural study of piton des neiges la reunion island to understand how intrusions and stresses control each other in basaltic volcanoes our study reveals that three perpendicular intrusions trends coexisted during the 2 myr history of the volcano a n120 140 e rift zone a perpendicular dike trend and swarms of subhorizontal intrusions hereafter called sill zones independently the inversion of fault slip data shows that incompatible paleostress fields recurrently occurred along with the intrusions a dominant nne ssw extension a perpendicular extension and strike slip or compressional regimes the orientations of paleostresses are consistent with the orientations of the three perpendicular intrusion populations we propose that stress accumulation in the edifice under the effect of repeated magma injections resulted in permutations of the principal axes of the stress tensor causing a reorientation of subsequent intrusions stress permutations were cyclical each cycle started with dike injections in an extensional stress field reducing the deviatoric stress and switching the axes of principal stresses and finished with sill intrusions in a compressional stress field sill zones acted as detachment planes restoring the extensional stress field and initiating a new cycle of permutations our model of stress permutations is in agreement with the pattern of eruptions and deformation observed at piton de la fournaise in contrast with the hawaiian model of spreading on a decollement stress permutations in la reunion s volcanoes imply that the basal deformation of the edifices if any is not sufficient to compensate the reduction of deviatoric stress caused by intrusions

early diagenetic processes fluxes and reaction rates in sediments of the south atlantic abstract porewaters recovered from sediment cores gravity corers box corers and multicorers from various subrogions of the south atlantic amazon river mouth equatorial upwelling congo river mouth benguela coastal upwelling area and angola basin were investigated geochemically objectives included determination of eh ph oxygen nitrate sulfate alkalinity phosphate ammonium fluoride sulfide cal mg sr fe mn and si in order to quantify organic matter diagenesis and related mineral precipitation and dissolution processes porewater profiles from the eastern upwelling areas of the south atlantic suggest that sulfate reduction in the deeper parts of the sediment may be attributed mainly to methane oxidation whereas organic matter degradation by sulfate reduction is restricted to the near surface sediments further a prominent concentration gradient change of sulfate and related mineralization products occurred typically in the upwelling sediments at a depth of 4 to 8 m far below the zone of bioturbation or bioirrigation because other sedimentological reasons seem to fail as explanations an early diagenetic sulfide oxidation to sulfate within the anoxic environment is discussed porewater profiles from the sediments of the amazon fan area are mainly influenced by reactions with fe iii phases the remarkable linearity of the concentration gradients of sulfate supports the idea of distinct reaction layers in these sediments in contrast to the upwelling sediments the sulfate gradient develops from the sediment surface to a sulfate reduction zone at a depth of 5 3 m probably because a reoxidation of sulfide is prevented by the reaction with iron oxides and the formation of iron sulfide minerals a comparison of organic matter degradation rates from the different areas of the south atlantic show the expected relationship to primary productivity oxygen is the dominating oxidant whereas organic matter degradation by nitrate mn iv and probably also fe iii reduction is several orders of magnitude lower sulfate reduction is quantitatively of similar importance as oxygen respiration in the organic rich sediments but may also include methane oxidation reoxidation of ammonium and mn2 by oxygen or nitrate do not alter significantly the estimation of organic matter degradation in the oxic zone but may contribute to the nitrate reduction in suboxic layers

dissolved organic matter in abyssal sediments core recovery artifacts we report measurements of pore water dissolved organic carbon doc dissolved organic nitrogen total dissolved carbohydrates dissolved free monosaccharides and ammonium in recovered deep sea sediments from the porcupine abyssal plain pap northeast atlantic there were distinct maxima close to the sediment water interface of these constituents at all times of the year the very high diffusive effluxes calculated from these porewater distributions were not compatible with simultaneous sediment trap measurements of particulate organic carbon nitrogen and carbohydrate fluxes toward the seafloor effluxes calculated from pore water doc distributions in recovered cores from another atlantic deep sea site showing almost identical maxima as those at pap were more than an order of magnitude greater than simultaneous in situ chamber doc flux measurements we suggest that the dissolved organic matter maxima are predominantly artifacts induced by lysis of or leakage from mainly bacterial biomass resulting from decompression and or warming during recovery of the sediment cores from the abyssal seafloor temperature elevation during core recovery from the abyss gives a n2 saturation of about 150 and the combined effect of warming and decompression results in a co2 saturation of about 135 which together plausibly are associated with bubble formation creating cell bursting previous estimates of microbial biomass in abyssal sediments may be underestimates because of the difficulty of counting lysed bacterial cells since exoenzymes are inducible previous measurements of their activities in recovered abyssal sediments may be overestimates

the global ocean flux of particulate organic carbon areal distribution and magnitude the magnitude and distribution of the particulate organic carbon poc rain rate to the seafloor in the atlantic pacific and indian ocean basins between 61 n and 61 s has been estimated from benthic oxygen flux estimates for water depths 1000 m only the calculation utilizes the extensive data sets of sedimentary organic carbon caco3 and accumulation rate to extrapolate between individual benthic flux measurement sites using an empirically derived correlation between the seafloor oxygen flux and these parameters the poc flux through the 1000 m depth horizon was then estimated from published correlations between sediment trap determined fluxes and water depth total oxygen utilization in the deep ocean is estimated to be 1 2 1014 mol o2 yr 1 a value that agrees well with previous estimates which were based on surface water primary productivity sediment trap and depth relationships and with deep water respiration rates estimated from apparant oxygen utilization aou 14c relationships on the basis of the derived global ocean flux distribution it is concluded that 1 dissolved organic carbon doc inputs are not required to account for estimated deep water respiration rates 2 the majority of the poc input to the deep ocean occurs within 30 of the equator 3 the proportion of primary production that reaches the deep sea does not vary greatly with latitude 4 gyre and continental margin regions contribute roughly equally to the deep poc flux with a relatively minor contribution from the equatorial divergence region 5 of the estimated 7 2 1013 mol c yr 1 of poc that sinks below the 1000 m depth horizon 45 3 3 1013 mol c yr 1 reaches the seafloor where it is oxidized 6 when normalized to basin area average deep flux rates in the atlantic and pacific are similar while highest rates are observed in the indian ocean and 7 the results can be fully reconciled only if the benthic flux of doc is significantly less than the benthic o2 flux

cointrusive shear displacement by sill intrusion in a detachment a numerical approach sheared sills are observed at piton des neiges the eroded basaltic volcano of la reunion and are a suspected cause of the coeruptive flank displacement of piton de la fournaise in 2007 we performed a 2 d numerical study to quantify the perturbation induced by sill injection within a volcanic edifice magma is considered as an inviscid and pressurized fluid injected in an initially stable edifice under gravity controlled extension two cases of injection are tested in an elastic homogeneous edifice or along a detachment controlled by a friction law we show that sill injection induces tangential displacements this effect is strongly increased when sills are emplaced along a detachment producing extension behind the injection and potentially ending in a large scale flank collapse sill injections can thus explain the cointrusive shear deformation observed at piton des neiges and the tangential displacements measured at piton de la fournaise in 2007

geochemical and biological recovery of the disturbed seafloor in polymetallic nodule fields of the clipperton clarion fracture zone ccfz at 5 000 m depth environmental data were obtained on the nodule fields of the clipperton clarion fracture zone at 5 000 m depth in june 2004 during the nodinaut cruise the long term effects of physical disturbance made by a dredge 26 yr ago on the sediment were investigated we focused our study on its track which is still visible on the bottom the first major consequence of the passage of this equipment was to remove 4 cm 6 0 5 cm of superficial sediment the physical and chemical properties of this disturbed sediment sampled in the track did not change significantly over time and has not shown any recovery since the disturbance however an exception was observed for depth variations of manganese concentration in the sediment which were similar in the track to those in the surrounding undisturbed sediment and can be explained by the diffusion over time of oxygen from the sea water on the other hand the biological activity measured in the track with the respirometer rap2 carried by the submersible nautile did not differ from the unperturbed site which suggests that the benthic fauna has completely recovered as have nutrient fluxes at the water sediment interface

stratospheric variability of wave activity and parameters in equatorial coastal and tropical sites during the west african monsoon recent numerical studies in stratospheric dynamics and its variability as well as climate have highlighted the need of more observational analyses to improve simulation of the west african monsoon wam in this paper activity and spectral characteristics of short scale vertical waves wavelengths 4 km are analysed in equatorial coastal and tropical lower stratosphere during the wam a first detailed description of such waves over west africa is derived from high resolution vertical profiles of temperature and horizontal wind obtained during intensive observation period of the african monsoon multidisciplinary analyses amma campaign 2006 monthly variation of wave energy density is revealed to trace the progression of the inter tropical convergence zone itcz over west africa mesoscale inertia gravity waves structures with vertical and horizontal wavelengths of 1 5 2 5 and 400 1100 km respectively and intrinsic frequencies of 1 1 2 2 f or periods 2 days are observed in the tropical ls with intense activity during july and august when the wam is installed over the tropical west africa over equatorial region gravity waves with intrinsic frequencies of 1 4 4 f or periods 5 2 days vertical wavelength of 2 1 km and long horizontal wavelengths of 1300 km are intense during the wam coastal phase from july to october gravity waves with intrinsic frequencies of 1 2 3 8 f or periods 6 days vertical wavelength of 2 1 km and horizontal wavelengths of 1650 km are less intense during the wam sahelian phase of the wam march june unlike potential energy density kinetic energy density is observed to be a good proxy for the activity of short scale vertical waves during the wam because quasi inertial waves are dominant long term wave activity variation from january 2001 to december 2009 highlights strong year to year variation superimposed on convective activity and quasi biennial oscillation like variations especially above tropical stations

oxygen consumption rates in pelagic sediments from the central pacific first estimates from microelectrode profiles abstract oxygen profiles in pelagic sediments from the manganese nodule program calcareous and siliceous ooze sites manop sites c and s in the central pacific ocean were measured with microelectrodes and are used to predict oxygen consumption rates beneath the sediment water interface we explain possible artifacts which occur during sample recovery and argue that minimum estimates of 0 083 and 0 025 moles o 2 cm 2 day c and s respectively can be calculated from the data these oxygen consumption rates are in good agreement with in situ respirometer measurements previously reported for comparable sediments in the north pacific but previous estimates based on modeling of pore water nitrate profiles at both sites are two to five times smaller than our minimum fluxes the differences in oxygen fluxes calculated by the two methods are probably in part due to uncertainty in the assumptions inherent in the nitrate model however non steady state fluctuations in particulate organic matter fluxes could also be a reason for the disparity

large scale waves in the mesosphere and lower thermosphere observed by saber observations made by the sounding of the atmosphere using broadband emission radiometry saber instrument on board nasa s thermosphere ionosphere mesosphere energetics and dynamics timed satellite have been processed using salby s fast fourier synoptic mapping ffsm algorithm the mapped data provide a first synoptic look at the mean structure and traveling waves of the mesosphere and lower thermosphere mlt since the launch of the timed satellite in december 2001 the results show the presence of various wave modes in the mlt which reach largest amplitude above the mesopause and include kelvin and rossby gravity waves eastward propagating diurnal oscillations non sunsynchronous tides and a set of quasi normal modes associated with the so called 2 day wave the latter exhibits marked seasonal variability attaining large amplitudes during the solstices and all but disappearing at the equinoxes saber data also show a strong quasi stationary rossby wave signal throughout the middle atmosphere of the winter hemisphere the signal extends into the tropics and even into the summer hemisphere in the mlt suggesting ducting by westerly background zonal winds at certain times of the year the 5 day rossby normal mode and the 4 day wave associated with instability of the polar night jet are also prominent in saber data

shallow flank deformation at cumbre vieja volcano canary islands implications on the stability of steep sided volcano flanks at oceanic islands abstract volcano flank instability has been recognized at many volcanoes around the globe structural morphological geodetic and geophysical evidence supports the continuous deformation of their flanks while identification of instability has been recognized in well documented examples until recently the initial stages of such processes have been difficult to capture using a combination of geological geodetic and geophysical data analysis we study the stability of the cumbre vieja new descending radar interferometric data covering a volcanologically quiet period between 1992 and 2008 at cumbre vieja indicate movement away from the satellite on the western volcano flank using an inversion of stacked velocity maps we determine the geometry and slip for a near horizontal dislocation beneath the western flank of cumbre vieja our ground deformation modelling results position and depth are in agreement with a low density anomaly constrained by gravity data the previously undetected intereruptive ground deformation at cumbre vieja volcano flanks was explained as an indicator of a kinematic passive response model of the flank where the flanks were mobilized only during periods of magmatic activity shallow dike intrusions and remained stable and undeformed during intereruptive periods here we present new results indicating that active creeping stress release due to gravitational loading is also a dominant deformation mechanism for current intereruptive periods at cumbre vieja which would contribute positively to the stabilization of the edifice and reduce the associated hazard related to the volcano flank dynamics this study at cumbre vieja can be considered as a prototype for similar volcanoes around the macaronesian islands group e g fogo teide el hierro pico and elsewhere

implications of transient deformation in the northern basin and range western united states transient deformation events observed in global positioning system gps data from the basin and range extensional province may illuminate qualitatively similar transient events observed in subduction zones and other tectonic environments we model gps time series at 22 sites using a combination of hyperbolic tangent function analysis and elastic load deformation estimated from climatological data we identify two transient events 2000 4 and 2004 4 with roughly similar timing and displacement to those described previously by other researchers the first few years of gps observations adopted as a reference state in earlier studies are found to be anomalous our results differ from previous studies in two respects first a significant component of northward transient motion occurs during both events despite a reversal of sign in east component motion second sites move coherently in the eastern as well as the western basin and range surface mass loading the largest source of transient stress forcing in the region exhibits no evidence of a simple relationship to the deformation transients prior studies inferred slip on a single megadetachment at the moho but that hypothesis assumes negligible ductile deformation of the lower crust and a dry olivine rheology for the uppermost mantle recent measurements of crustal quartz abundance and effective elastic thickness suggest both assumptions are unlikely basin and range transients can be reconciled with the frictional slip mechanism widely accepted for subduction zone transients provided that slip is occurring on discontiguous detachment surfaces at midcrustal depths

spectral analysis of gravity wave activity in saber temperature data 1 since january 2002 the saber sounding of the atmosphere using broadband emission radiometry instrument has performed continuous measurements from near the tropopause into the thermosphere for the time period 29 january 2002 31 january 2006 we spectrally analyzed time series of weekly zonal root mean square gravity wave gw amplitudes for systematic intra annual annual and inter annual gw activity gws considered have horizontal wavelengths between 100 km and zonal wave number 6 and vertical wavelengths between 5 30 km height latitude cross sections of spectral amplitudes and phases between 20 100 km and 55 s 55 n show several relevant oscillations a strong semiannual variation is evident in the high latitude upper stratosphere mesosphere annual components reveal two isolated maxima at mid latitudes in both hemispheres associated with the winter polar vortices and summertime maxima in the subtropics biennial amplitudes in the equatorial stratosphere coincide with the descending westerly shear phase and can be attributed to the quasi biennial oscillation

three dimensional seismic velocity structure of mauna loa and kilauea volcanoes in hawaii from local seismic tomography we present a new three dimensional seismic velocity model of the crustal and upper mantle structure for mauna loa and kilauea volcanoes in hawaii our model is derived from the first arrival times of the compressional and shear waves from about 53 000 events on and near the island of hawaii between 1992 and 2009 recorded by the hawaiian volcano observatory stations the vp model generally agrees with previous studies showing high velocity anomalies near the calderas and rift zones and low velocity anomalies in the fault systems the most significant difference from previous models is in v p vs structure the high vp and high v p vs anomalies below mauna loa caldera are interpreted as mafic magmatic cumulates the observed low vp and high v p vs bodies in the kaoiki seismic zone between 5 and 15 km depth are attributed to the underlying volcaniclastic sediments the high vp and moderate to low vp vs anomalies beneath kilauea caldera can be explained by a combination of different mafic compositions likely to be olivine rich gabbro and dunite the systematically low vp and low vp vs bodies in the southeast flank of kilauea may be caused by the presence of volatiles another difference between this study and previous ones is the improved vp model resolution in deeper layers owing to the inclusion of events with large epicentral distances the new velocity model is used to relocate the seismicity of mauna loa and kilauea for improved absolute locations and ultimately to develop a high precision earthquake catalog using waveform cross correlation data 2014 american geophysical union all rights reserved

interseismic quiescence and triggered slip of active normal faults of kīlauea volcano s south flank during 2001 2018 the mobile south flank of k lauea volcano hosts two normal fault systems the koa e fault system kfs and the hilina fault system hfs in historical time at least three m 6 5 earthquakes have occurred on the basal detachment of the k lauea volcano s south flank with the most recent being the 4 may 2018 m6 9 earthquake here we analyze kinematic global positioning system data collected from 2001 to 2017 and interferometric synthetic aperture radar data before during and after the 2018 m6 9 earthquake to determine the crustal motion across the hfs and kfs faults our results indicate that the hfs faults did not significantly slip during the interseismic period from 2007 to 2011 despite its substantial magnitude interferometric synthetic aperture radar insar data show that the 2018 m6 9 earthquake triggered subcentimeter level slip along sections of the previously mapped hfs branches up to 20 cm of offset occurred on what appears to be a newly formed or previously unknown fault near the eastern end of the hfs during the 3 months following the m6 9 earthquake up to 30 cm of slip occurred along the kfs which helps accommodate rapid large scale subsidence of k lauea s summit region as large volumes of summit reservoir magma fed the lower east rift zone eruption the hfs appears to activate only in concert with large earthquakes on the basal detachment the kfs on the other hand moves both seismically during small local earthquakes and aseismically in response to nearby earthquakes and caldera subsidence

dykes and structures of the ne rift of tenerife canary islands a record of stabilisation and destabilisation of ocean island rift zones many oceanic island rift zones are associated with lateral sector collapses and several models have been proposed to explain this link the north east rift zone nerz of tenerife island spain offers an opportunity to explore this relationship as three successive collapses are located on both sides of the rift we have carried out a systematic and detailed mapping campaign on the rift zone including analysis of about 400 dykes we recorded dyke morphology thickness composition internal textural features and orientation to provide a catalogue of the characteristics of rift zone dykes dykes were intruded along the rift but also radiate from several nodes along the rift and form en echelon sets along the walls of collapse scars a striking characteristic of the dykes along the collapse scars is that they dip away from rift or embayment axes and are oblique to the collapse walls this dyke pattern is consistent with the lateral spreading of the sectors long before the collapse events the slump sides would create the necessary strike slip movement to promote en echelon dyke patterns the spreading flank would probably involve a basal decollement lateral flank spreading could have been generated by the intense intrusive activity along the rift but sectorial spreading in turn focused intrusive activity and allowed the development of deep intra volcanic intrusive complexes with continued magma supply spreading caused temporary stabilisation of the rift by reducing slopes and relaxing stress however as magmatic intrusion persisted a critical point was reached beyond which further intrusion led to large scale flank failure and sector collapse during the early stages of growth the rift could have been influenced by regional stress strain fields and by pre existing oceanic structures but its later and mature development probably depended largely on the local volcanic and magmatic stress strain fields that are effectively controlled by the rift zone growth the intrusive complex development the flank creep the speed of flank deformation and the associated changes in topography using different approaches a similar rift evolution has been proposed in volcanic oceanic islands elsewhere showing that this model likely reflects a general and widespread process this study however shows that the idea that dykes orient simply parallel to the rift or to the collapse scar walls is too simple instead a dynamic interplay between external factors e g collapse erosion and internal forces e g intrusions is envisaged this model thus provides a geological framework to understand the evolution of the nerz and may help to predict developments in similar oceanic volcanoes elsewhere

pore waters of the central pacific ocean nutrient results interstitial waters from the manop siliceous and calcareous ooze sites in the central pacific ocean were recovered by shipboard squeezing and centrifuging techniques and an in situ harpoon sampler the pore waters were analyzed for nutrients carbonate system species mn 2 ca 2 total alkaline earth metals and dissolved oxygen siliceous ooze site only in calcareous sediments the co 2 alkalinity po 4 3 and ca 2 results obtained from shipboard techniques are significantly different than those recovered in situ the other species measured as well as all of the data from the siliceous ooze site reveal no significant dependence on the method used to sample the pore water the relative changes in o 2 no 3 mn 2 alkalinity and co 2 indicate that respiration using o 2 no 3 and mno 2 as electron acceptors is the dominant reaction affecting the pore water species we develop a model which simulates the fate of pore water oxygen and nitrate and particulate organic carbon in sediments this model includes the effects of pore water diffusion oxygen and nitrate respiration sediment accumulation sediment mixing and changes in sediment porosity we observe that factor of 2 variations in the rates of sediment mixing and accumulation have only a minor effect on the pore water profiles the major factor controlling the pore water profiles is the flux of organic carbon across the sediment water interface we conclude that the large intra site variability observed in the interstitial water nitrate profiles is probably caused by small scale variations in the flux of organic material

in situ measurements of calcium carbonate dissolution rates in deep sea sediments benthic fluxes of alkalinity carbon dioxide and oxygen have been measured using an in situ incubation chamber at three sites manop sites c and s and pacflux site sc in the central equatorial north pacific at two carbonate rich sites c and sc a budget for oxygen alkalinity and tco2 fluxes indicate a net caco3 dissolution rate of approximately 0 4 mmol m 2 day 1 this rate is only 20 of previous estimates but is consistent with a dissolution rate constant predicted from laboratory experiments with deep sea sediments and derived from in situ flux measurements in sediments of the southern california borderland organic matter oxidation in the sediment column provides the acid for 60 100 of the calcium carbonate dissolution occurring at these sites with the remainder derived from undersaturated bottom water at a low carbonate site s no carbonate dissolution in the sediment or on the sea floor is apparent although sediment traps indicate a rain of caco3 through 3400 m the rates of remineralization relative to resuspension or erosion at this site must differ for organic carbon and calcium carbonate so that carbonate grains reaching the sea floor are physically removed by erosion or resuspension before they dissolve while organic carbon is largely oxidized before it can be physically removed

pore water profiles and numerical modelling of biogeochemical processes in peru basin deep sea sediments abstract an extensive set of pore water profiles including o 2 no 3 no 2 nh 4 po 4 3 fe 2 mn 2 so 4 2 sio 4 4 ph and alkalinity as well as solid phase data on organic carbon content and porosity in 18 sediment cores obtained from five areas in the peru basin rv sonne 106 expedition in 1996 is presented the pore water profiles indicate that early diagenesis progresses through oxygen respiration denitrification and manganese iv reduction while the subsequent redox states iron iii reduction sulphate reduction and methanogenesis cannot be observed from the dissolved phase in these deep sea sediments a numerical diagenetic model was applied to the data in order to derive parameters such as the depositional flux of metabolizable organic matter or the bioturbation intensity that control the geochemical conditions in the deep sea floor and could not be obtained directly by measurements moreover the numerical simulations show that even those pore water no 3 profiles that decline non linearly to zero concentration are not compatible with a steady state assumption they can be explained only by transient downward progression of a nitrate front

quantification of diffusive benthic fluxes of nitrate phosphate and silicate in the southern atlantic ocean pore water data from surface sediments and bottom water data at 180 locations were used to create distribution maps of diffusive benthic release rates of nitrate phosphate and silicate in the southern atlantic ocean for water depths 1000 m geostatistical methods of variogram analysis and kriging were used for data interpolation since benthic fluxes are controlled by organic matter degradation and dissolution processes and therefore by the supply of organic matter to the sediment surface the distribution pattern of all investigated constituents should reflect a general coupling to surface water productivity this seems to be true for the most part of the oligotrophic central south atlantic and the upwelling area off southwest africa striking regional differences in this regard however exist for the eastern equatorial region where unexpectedly low fluxes were calculated and the argentine basin where benthic fluxes are very high the argentine basin obviously receives a higher input of degradable dissolvable material whereas in the eastern equatorial region the low benthic fluxes are possibly due to intense nutrient recycling within the water column estimated fluxes vary considerably over the entire region no3 10 180 mmol m 2 yr 1 po4 2 11 mmol m 2 yr 1 and si 0 0 65 mol m 2 yr 1 areas of highest release rates are the continental margins off southwest africa and off argentina the investigated area comprises a total of approximately 32 106 km2 between 8 n and 40 50 s our estimations reveal benthic release rates of 1 55 l012 mol no3 yr 1 3 5 l010 mol po4 yr 1 and 2 1 1012 mol si yr 1 open ocean areas with middle to low fluxes contribute about 70 80 of the total estimated fluxes the release of phosphate is probably underestimated because of core recovery artifacts and is therefore based on the assumption that fluxes are not lower than 0 25 mmol m 2 yr 1 at any location of the studied area the investigated area represents about one tenth of the world deep ocean without the arctic ocean assuming the south atlantic to be representative we calculate annual global release rates of 15 l012 mol no3 32 l010 mol po4 and 20 1012 mol si if our estimates are correct about 4 6 of silicate 3 4 of nitrate and 1 of phosphate annually produced in the surface waters are remineralized in surface sediments from water depths 1000 m

seismic tomography of compressional wave attenuation structure for kilauea volcano hawai i we present a frequency independent three dimensional 3 d compressional wave attenuation model indicated by the reciprocal of quality factor qp for kilauea volcano in hawai i we apply the simul2000 tomographic algorithm to the attenuation operator t values for the inversion of qp perturbations through a recent 3 d seismic velocity model and earthquake location catalog the t values are measured from amplitude spectra of 26708 p wave arrivals of 1036 events recorded by 61 seismic stations at the hawaiian volcanology observatory the 3 d qp model has a uniform horizontal grid spacing of 3 km and the vertical node intervals range between 2 and 10 km down to 35 km depth in general the resolved qp values increase with depth and there is a correlation between seismic activity and low qp values the area beneath the summit caldera is dominated by low qp anomalies throughout the entire resolved depth range the southwest rift zone and the east rift zone exhibit very high qp values at about 9 km depth whereas the shallow depths are characterized with low qp anomalies comparable with those in the summit area the seismic zones and fault systems generally display relatively high qp values relative to the summit the newly developed qp model provides an important complement to the existing velocity models for exploring the magmatic system and evaluating and interpreting intrinsic physical properties of the rocks in the study area

coupled nitrification denitrification in sediment of the eastern bering sea shelf leads to 15n enrichment of fixed n in shelf waters 1 we studied the nitrogen biogeochemistry of the ice covered eastern bering sea shelf using the isotope ratios 15n 14n and 18o 16o of no3 and other n species the 15n 14n of late winter no3 on the shelf decreases inshore and is inversely correlated with bottom water nh4 consistent with an input of low 15n 14n no3 from partial nitrification of nh4 remineralized from the sediments an inshore 15n 14n increase in total dissolved n tdn suggests that 1 the sediment derived nh4 is elevated in 15n due to the same partial nitrification that yields the low 15n 14n no3 and 2 15n deplete no3 from partial nitrification within the sediments is denitrified to n2 the proportion of newly nitrified no3 on the shelf evidenced by an inshore decrease in no3 18o 16o is correlated with the n deficit further implicating nitrification coupled to denitrification however a simple n isotope budget indicates a comparable rate of denitrification supported by diffusion of no3 into the sediments the isotopic impact of benthic n loss is further demonstrated by a correlation between the 15n 14n of shelf surface sediment and the n deficit of the overlying water column both of which increase inshore and northward as well as by arctic no3 isotope data indicating that the fixed n transported through bering strait has a 15n 14n higher than is found in the open bering sea the significant net isotope effect of benthic n loss on the bering shelf 6 8 is at odds with previous assumptions regarding the global ocean s n isotope budget

slow slip and tremor search at kilauea volcano hawaii 1 kilauea volcano hawaii has hosted a long series of slow slip events observed since the installation of the continuous gps network in 1996 kilauea s slow slip events are inferred to occur on the decollement fault at 8 km depth beneath its south flank with a location updip of the epicenters of large regular earthquakes fault slip typically lasts about two days and the events have magnitudes equivalent to mw 5 3 6 0 while slow slip events in subduction zones are commonly accompanied by tectonic tremor also called nonvolcanic tremor no tremor has yet been reported in association with kilauea s slow slip events instead there are swarms of small triggered earthquakes which is a characteristic only seen at select subduction zones e g boso and hikurangi a temporary array of seismometers was installed at kilauea in 2007 in anticipation of a slow slip event here we use several established methods to perform a systematic search for tectonic tremor during geodetically defined slow slip events as well as searching for tremor triggered by teleseismic surface waves we do not detect tectonic tremor using any of these methods although we are able to detect episodes of previously identified deep offshore volcanic tremor at 15 20 km depth and volcanic tremor from kilauea although kilauea s seismic network may not be adequate to observe tectonic tremor because hawaii is seismically noisy and its crust is highly attenuating it is also possible that the specific fault conditions on kilauea s decollement are not conducive to such tremor generation

relationships between volcano gravitational spreading and magma intrusion volcano spreading with its characteristic sector grabens is caused by outward flow of weak substrata due to gravitational loading this process is now known to affect many present day edifices a volcano intrusive complex can form an important component of an edifice and may induce deformation while it develops such intrusions are clearly observed in ancient eroded volcanoes like the scottish palaeocene centres or in geophysical studies such as in la reunion or inferred from large calderas such as in hawaii the canaries or galapagos volcanoes volcano gravitational spreading and intrusive complex emplacement may act simultaneously within an edifice we explore the coupling and interactions between these two processes we use scaled analogue models where an intrusive complex made of golden syrup is emplaced within a granular model volcano based on a substratum of a ductile silicone layer overlain by a brittle granular layer we model specifically the large intrusive complex growth and do not model small scale and short lived events such as dyke intrusion that develop above the intrusive complex the models show that the intrusive complex develops in continual competition between upward bulging and lateral gravity spreading the brittle substratum strongly controls the deformation style the intrusion shape and also controls the balance between intrusive complex spreading and ductile layer related gravitational spreading in the models intrusive complex emplacement and spreading produce similar structures to those formed during volcano gravitational spreading alone i e grabens folds en echelon fractures therefore simple analysis of fault geometry and fault kinetic indicators is not sufficient to distinguish gravitational from intrusive complex spreading except when the intrusive complex is eccentric from the volcano centre however the displacement fields obtained for 1 a solely gravitational spreading volcano and for 2 a gravitational spreading volcano with a growing and spreading intrusive complex are very different consequently deformation fields like those obtained from geodetic monitoring can give a strong indication of the presence of a spreading intrusive complex we compare the models with field observations and geophysical evidence on active volcanoes such as la reunion island indian ocean ometepe island nicaragua and eroded volcanic remnants such as ardnamurchan scotland and suggest that a combination between gravitational and intrusive complex spreading has been active

kilauea slow slip events identification source inversions and relation to seismicity 1 several slow slip events beneath the south flank ofkilauea volcano hawaii have been inferred from transient displacements in daily gps positions to search for smaller events that may be close to the noise level in the gps time series we compare displacement fields on kilauea s south flank with displacement patterns in previously identified slow slip events matching displacement patterns are found for several new candidate events although displacements are much smaller than previously identified events one of the candidates 29 may 2000 is coincident with a microearthquake swarm as are all of the previously identified slow slip events the microearthquakes follow the onset of slow slip implying that they are triggered by stress changes during slip the new slow slip event brings the total number of events on kilauea between 1997 and 2007 to eight the smallest having m w 5 3 and the largest having m w 6 0 while the recurrence time between the four largest events is 2 11 0 01 years the repeat time for all eight events is 0 9 0 6 years we invert for the fault geometry and distribution of slip during the slow slip events the optimal source depths of 5 km assuming uniform slip dislocations in an elastic half space are considerably shallower than the accompanying swarm earthquakes 6 5 8 5 km which would place the earthquakes in a zone of decreased coulomb stress inversions including the effects of topography and layered elastic structure in the forward models favor depths comparable to microearthquake depths such that the earthquakes are located in a region of increased coulomb stress we also invert for time dependent fault slip directly from the 30 s gps phase observations constraining the source to the optimal uniform slip geometry on the basis of these inversions the larger events last between 1 5 2 2 days the data are unable to resolve migration of slip along the fault the temporal pattern of accompanying microearthquakes is consistent with the fault slip history assuming a seismicity rate theory based on rate and state friction making the swarm earthquakes coshocks and aftershocks of the slow slip events

kelvin wave variability near the equatorial tropopause observed in gps radio occultation measurements 1 temperature fields in the equatorial upper troposphere and lower stratosphere derived from gps radio occultation measurements for 2001 2002 show evidence for planetary scale kelvin waves these waves have a characteristic eastward phase tilt with height and typical vertical wavelengths of 4 8 km the kelvin waves exhibit coherent vertical structure over 12 25 km with maximum amplitudes near the tropical tropopause 17 km the waves are often quasi stationary near the tropopause but exhibit regular eastward propagation in the lower stratosphere with periods near 20 days the quasi stationary waves modulate the climatological cold tropopause over indonesia the transient lower stratospheric waves show enhanced amplitudes coincident with the descending westerly shear phase of the quasi biennial oscillation qbo correlations with outgoing long wave radiation olr data show that global temperature patterns over 12 17 km with characteristic kelvin wave structure vary coherently with transient deep convection over indonesia

the 2010 slow slip event and secular motion at kilauea hawai i inferred from terrasar x insar data we present here a small baseline subset sbas algorithm to extract both transient and secular ground deformations on the order of millimeters in the presence of tropospheric noise on the order of centimeters when the transient is of short duration and known time and the background deformation is smooth in time we applied this algorithm to study the 2010 slow slip event as well as the secular motion of kilauea s south flank using 49 terrasar x images we also estimate the tropospheric delay variation relative to a given reference pixel using an interferometric synthetic aperture radar insar sbas approach we compare the insar sbas solution for both ground deformation and tropospheric delays with existing gps measurements and confirm that the ground deformation signal and tropospheric noise in insar data are successfully separated we observe that the coastal region on the south side of the hilina pali moves at a higher background rate than the region north side of the pali we also conclude that the 2010 slow slip event sse displacement is mainly horizontal and the maximum magnitude of the 2010 sse vertical component is less than 5 mm

earthquakes triggered by silent slip events on kīlauea volcano hawaii silent earthquakes or slow slip events happen so slowly that they cannot be detected by conventional seismographs but now the availability of gps data means that they can be followed in detail segall et al report on a series of small earthquakes on k lauea volcano hawaii the earthquakes at depths of 7 to 8 km appear to be triggered by otherwise silent slow slips though small triggered earthquakes of this type can be used to help quantify the increased hazard due to slow slip events slow slip events or silent earthquakes have recently been discovered in a number of subduction zones including the nankai trough1 2 3 in japan cascadia4 5 and guerrero6 in mexico but the depths of these events have been difficult to determine from surface deformation measurements although it is assumed that these silent earthquakes are located along the plate megathrust this has not been proved slow slip in some subduction zones is associated with non volcanic tremor7 8 but tremor is difficult to locate and may be distributed over a broad depth range9 except for some events on the san andreas fault10 slow slip events have not yet been associated with high frequency earthquakes which are easily located here we report on swarms of high frequency earthquakes that accompany otherwise silent slips on k lauea volcano hawaii for the most energetic event in january 2005 the slow slip began before the increase in seismicity the temporal evolution of earthquakes is well explained by increased stressing caused by slow slip implying that the earthquakes are triggered the earthquakes located at depths of 7 8 km constrain the slow slip to be at comparable depths because they must fall in zones of positive coulomb stress change triggered earthquakes accompanying slow slip events elsewhere might go undetected if background seismicity rates are low detection of such events would help constrain the depth of slow slip and could lead to a method for quantifying the increased hazard during slow slip events because triggered events have the potential to grow into destructive earthquakes

the spectrum of persistent volcanic flank instability a review and proposed framework based on kīlauea piton de la fournaise and etna abstract persistent motion of the south flank of k lauea volcano hawai i has been known for several decades but has only recently been identified at other large basaltic volcanoes namely piton de la fournaise la reunion and etna sicily thanks to the advent of space geodetic techniques nevertheless understanding of long term flank instability is based largely on the example of k lauea despite the large differences in the manifestations and mechanisms of the process when viewed through a comparative lens for example the rate of flank motion at k lauea is several times that of etna and piton de la fournaise and is accommodated on a slip plane several km deeper than is probably present at the other two volcanoes gravitational spreading also appears to be the dominant driving force at k lauea given the long term steady motion of the volcano s south flank regardless of eruptive intrusive activity whereas magmatic activity plays a larger role in flank deformation at etna and piton de la fournaise k lauea and etna however are both characterized by heavily faulted flanks while piton de la fournaise shows little evidence for flank faulting a helpful means of understanding the spectrum of persistent flank motion at large basaltic edifices may be through a framework defined on one hand by magmatic activity which encompasses both magma supply and edifice size and on the other hand by the structural setting of the volcano especially the characteristics of the subvolcanic basement or subhorizontal intravolcanic weak zones a volcano s size and magmatic activity will dictate the extent to which gravitational and magmatic forces can drive motion of an unstable flank and possibly the level of faulting of that flank while the volcano s structural setting governs whether or not a plane of weakness exists beneath or within the edifice and can facilitate flank slip considering persistent flank instability using this conceptual model is an alternative to using a single volcano as a type example especially given that the example is usually k lauea which defines an extreme end of the spectrum and can provide a basis for understanding why flank motion may or may not exist on other large basaltic volcanoes worldwide

slow slip events and seismic tremor at circum pacific subduction zones 1 it has been known for a long time that slip accompanying earthquakes accounts for only a fraction of plate tectonic displacements however only recently has a fuller spectrum of strain release processes including normal slow and silent earthquakes or slow slip events and continuous and episodic slip been observed and generated by numerical simulations of the earthquake cycle despite a profusion of observations and modeling studies the physical mechanism of slow slip events remains elusive the concurrence of seismic tremor with slow slip episodes in cascadia and southwestern japan provides insight into the process of slow slip a perceived similarity between subduction zone and volcanic tremor has led to suggestions that slow slip involves fluid migration on or near the plate interface alternatively evidence is accumulating to support the notion that tremor results from shear failure during slow slip global observations of the location spatial extent magnitude duration slip rate and periodicity of these aseismic slip transients indicate significant variation that may be exploited to better understand their generation most slow slip events occur just downdip of the seismogenic zone consistent with rate and state dependent frictional modeling that requires unstable to stable transitional properties for slow slip generation at a few convergent margins the occurrence of slow slip events within the seismogenic zone makes it highly likely that transitions in frictional properties exist there and are the loci of slow slip nucleation slow slip events perturb the surrounding stress field and may either increase or relieve stress on a fault bringing it closer to or farther from earthquake failure respectively this paper presents a review of slow slip events and related seismic tremor observed at plate boundaries worldwide with a focus on circum pacific subduction zones trends in global observations of slow slip events suggest that 1 slow slip is a common phenomena observed at almost all subduction zones with instrumentation capable of recording it 2 different frictional properties likely control fast versus slow slip 3 the depth range of slow slip may be related to the thermal properties of the plate interface and 4 the equivalent seismic moment of slow slip events is proportional to their duration mo different from the mo 3 scaling observed for earthquakes

aseismic deformation across the hilina fault system hawaii revealed by wavelet analysis of insar and gps time series abstract the hilina fault system hfs is located on the south flank of kilauea volcano and is thought to represent the surface expression of an unstable edifice sector that is active during seismic events such as the 1975 kalapana earthquake despite its potential for hazardous landsliding and associated tsunamis no fault activity has yet been detected by means of modern geodetic methods since the 1975 earthquake we present evidence from individual sar interferograms as well as cluster analysis and wavelet analysis of gps and insar time series which suggest an inferred differential motion at hfs to investigate the effect of atmospheric delay on the observed differential motion we implement a statistical approach using wavelet transforms we jointly analyze insar and continuous gps deformation data from 2003 to 2010 to estimate the likelihood that the subtle time dependent deformation signal about the hfs scarps is not associated with the atmospheric delay this integrated analysis reveals localized deformation components in the insar deformation time series that are superimposed on the coherent motion of kilauea s south flank the statistical test suggests that at 95 confidence level the identified differential deformation at hfs is not due to atmospheric artifacts since no significant shallow seismicity is observed over the study period we suggest that this deformation occurred aseismically

seasonal variations of gravity wave activity in the lower stratosphere over an antarctic peninsula station an 8 year series of 965 high resolution radiosonde soundings over rothera 67 degrees s 68 degrees w on the antarctic peninsula are used to study gravity wave characteristics in the lower stratosphere the gravity wave energy is shown to have a seasonal variation with peaks at the equinoxes the largest peak is around the spring equinox during the winter months and extending into the spring there is both an enhancement in the downward propagating wave activity and a reduction in the amount of critical level filtering of upward propagating mountain waves the horizontal propagation directions of the gravity waves were determined using hodographs it was found that there is a predisposition toward northward and westward propagating waves above rothera this is in agreement with previous observations of gravity wave momentum flux in the wintertime mesosphere over rothera these results are consistent with a scenario whereby the stratospheric gravity wavefield above rothera is determined by a combination of wind flow over topography generating waves from below and sources such as the edge of the polar stratospheric vortex generating waves from above especially during winter and spring

moderate magnitude earthquakes induced by magma reservoir inflation at kīlauea volcano hawai i 1 although volcano tectonic vt earthquakes often occur in response to magma intrusion it is rare for them to have magnitudes larger than m4 on 24 may 2007 two shallow m4 earthquakes occurred beneath the upper part of the east rift zone of k lauea volcano hawai i an integrated analysis of geodetic seismic and field data together with coulomb stress modeling demonstrates that the earthquakes occurred due to strike slip motion on pre existing faults that bound k lauea caldera to the southeast and that the pressurization of k lauea s summit magma system may have been sufficient to promote faulting for the first time we infer a plausible origin to generate rare moderate magnitude vts at k lauea by reactivation of suitably oriented pre existing caldera bounding faults rare moderate to large magnitude vts at k lauea and other volcanoes can therefore result from reactivation of existing fault planes due to stresses induced by magmatic processes

an increment of volcano collapse kinematics of the 1975 kalapana hawaii earthquake abstract earthquakes on kilauea volcano can be even more hazardous than volcanic eruptions the most recent large earthquake was the 1975 kalapana quake which generated a locally damaging tsunami over 8 m of horizontal surface displacement and 3 m of subsidence at the coast the seismic magnitude estimates for this earthquake range from ms 7 2 to mw 7 7 the complexity of the seismic data is matched by the complex surface deformation that was observed with a combination of leveling tilt and electronic distance measurements edm the geodetic data shows evidence of collapse of the caldera due to magma withdrawal localized subsidence over the rift zone normal faulting associated with shallow slumping along the hilina pali and displacement on the basal detachment fault we model the summit caldera rift zones and basal detachment fault as dislocations in an elastic half space to better quantify the sources of deformation related to this devastating event using inversion techniques that allow us to let the data constrain the geometry and magnitude of these sources we find 0 04 km3 of magma withdrawal at the summit between 3 5 m of opening along the rift zone and 7 1 m of slip along the basal detachment at 8 3 km depth models that allow for finer spatial resolution of slip on the detachment show that the largest slip occurred west of the seismically recorded earthquake hypocenter along the region of the fault below the coast and that the majority of the fault slip occurred south of the region of microseismicity our best fitting model has a geodetic moment of 4 1 1020 nm mw 7 7 which is consistent with tsunami models and recent analysis of long period seismic data the residual displacements of sites located in the hanging wall of the hilina pali slump system which were not used in the inversion of the other sources suggest that triggered shallow slumping contributed several meters of horizontal displacement to the coseismic displacement at these sites

magmatically triggered slow slip at kilauea volcano hawaii we demonstrate that a recent dike intrusion probably triggered a slow fault slip event sse on kilauea volcano9s mobile south flank our analysis combined models of advanced land observing satellite interferometric dike intrusion displacement maps with continuous global positioning system gps displacement vectors to show that deformation nearly identical to four previous sses at kilauea occurred at far field sites shortly after the intrusion we model stress changes because of both secular deformation and the intrusion and find that both would increase the coulomb failure stress on possible sse slip surfaces by roughly the same amount these results in concert with the observation that none of the previous sses at kilauea was directly preceded by intrusions but rather occurred during times of normal background deformation suggest that both extrinsic intrusion triggering and intrinsic secular fault creep fault processes can lead to sses

simultaneous long term and short term slow slip events at the hikurangi subduction margin new zealand implications for processes that control slow slip event occurrence duration and migration 1 we document a sequence of simultaneous short term and long term slow slip events sses at the hikurangi subduction zone during the 2010 2011 period the sequence of short term events each 2 3 weeks in duration ruptured much of the shallow plate interface 15 km at central and northern hikurangi over a 6 month period was accompanied by microseismicity and involved patchy irregular migration of sse slip we suggest that the patchy migration of the short term sse is due to large scale 100 3500 km heterogeneities on the plate interface related to seamount subduction and sediment subduction and or underplating this is in contrast to a 2010 2011 long term sse at the central hikurangi margin which evolved steadily over 1 5 years and ruptured much of the plate interface between 20 and 70 km depth we suggest that the occurrence of long term versus short term sses at hikurangi is related to differences in effective normal stresses and relative heterogeneity of the subduction interface the long term sse sequence began 1 year before the short term sequence coulomb stress change models suggest that the long term sse may have triggered initiation of the subsequent short term sse sequence initiation of the short term sequence occurred in a region just updip of or within an interseismically locked portion of the plate interface and may be located within the updip transition from seismic to aseismic behavior alternatively it could be characteristic of a region undergoing partial interseismic coupling this is in contrast to sses observed elsewhere in the world that typically occur within the downdip transition from seismic to aseismic behavior

volcano monitoring using gps developing data analysis strategies based on the june 2007 kīlauea volcano intrusion and eruption 1 the global positioning system gps is one of the most common techniques and the current state of the art used to monitor volcano deformation in addition to slow several centimeters per year displacement rates gps can be used to study eruptions and intrusions that result in much larger tens of centimeters over hours days displacements it is challenging to resolve precise positions using gps at subdaily time intervals because of error sources such as multipath and atmospheric refraction in this paper the impact of errors due to multipath and atmospheric refraction at subdaily periods is examined using data from the gps network on k lauea volcano hawai i methods for filtering position estimates to enhance precision are both simulated and tested on data collected during the june 2007 intrusion and eruption comparisons with tiltmeter records show that gps instruments can precisely recover the timing of the activity

geodetic evidence and modeling of a slow small scale inflation episode in the thera santorini volcano caldera aegean sea abstract analysis of a radial geodetic monitoring record indicated small scale inflation of the nw part of the thera santorini caldera up to 10 cm baseline length increase between 1994 and 2000 corresponding to up to 2 10 5 strain and subsequent stabilization especially after 2006 as gps data indicate the southern part of the caldera on the contrary remained practically stable this partial caldera inflation was assigned to slow magma intrusion which was not associated with changes in the seismicity using a stochastic approach based on numerical analysis and the theory of graphs and sets the mogi source of this magmatic activity was identified between the nea kammeni and the therasia islets along a major tectonovolcanic lineament at a depth of around 1 km or possibly 5 5 km it remained stable during the whole small scale inflation period and was associated with small scale pressure changes slow deformation events have been observed in other volcanoes as well but they were associated with abrupt seismicity changes

precursors to dyke fed eruptions at basaltic volcanoes insights from patterns of volcano tectonic seismicity at kilauea volcano hawaii to investigate the physical controls on volcano tectonic vt precursors to eruptions and intrusions at basaltic volcanoes we have analyzed the spatial and temporal patterns of vt earthquakes associated with 34 eruptions and 23 dyke intrusions that occurred between 1960 and 1983 at kilauea in hawaii eighteen of the 57 magmatic events were preceded by an acceleration of the mean rate of vt earthquakes located close to the main shallow magma reservoir using a maximum likelihood technique and the bayesian information criterion for model preference we demonstrate that an exponential acceleration is preferred over a power law acceleration for all sequences these sequences evolve over time scales of weeks to months and are consistent with theoretical models for the approach to volcanic eruptions based on the growth of a population of fractures in response to an excess magma pressure among the remaining 40 magmatic events we found a significant correlation between swarms of vt earthquakes located in the mobile south flank of kilauea and eruptions and intrusions the behaviour of these swarms suggests that at least some of the magmatic events are triggered by transient episodes of elevated rates of aseismic flank movement which could explain why many eruptions and intrusions are not preceded by longer term precursory signals in none of the 57 cases could a precursory sequence be used to distinguish between the approach to an eruption or an intrusion so that even when a precursory sequence is recognized there remains an empirical chance of about 40 24 intrusions from 57 magmatic events of issuing a false alarm for an imminent eruption

simulation of early diagenetic processes in continental slope sediments off southwest africa the computer model cotam tested abstract pore water of marine sediments recovered from two stations of the continental slope off southwest africa were investigated we present computer simulations of in situ and laboratory concentration profiles of oxygen as well as laboratory concentration profiles of nitrate calcium ph and alkalinity the simulations were carried out with help of a numerical model cotam to describe the transport and the reaction of dissolved species in sediments cotam is based on an operator splitting approach comprising the independent calculation of transport and chemical reaction the consumption rates of oxygen and nitrate were determined by optimal fits to the measured pore water profiles of these species it could be shown that measured concentrations of nitrate in pore water correspond to a decomposition of organic matter with c n ratios between 3 and 3 7 however artificially increased subsurface nitrate concentrations due to core recovery cannot be excluded but our results show much greater deviations from expected concentrations assuming redfield stoichiometry than previously reported from comparative studies i e martin and sayles 1996 oxygen consumption in situ was shown to be distinctively lower than measured in multicorer cores after recovery simulations with varying denitrification rates indicate reduced diffusive nitrate release into the bottom water by up to 50 compared to shipboard results effects of nitrification and denitrification on pore water ph carbonate alkalinity and calcium concentrations were simulated by recalculating concentrations of these species with regard to calcite equilibrium for these calculations we used the standard software phreeqe as a subroutine of cotam calcium and carbonate alkalinity increase due to solid phase calcite dissolution ph was calculated to be an order of magnitude lower within the zone of oxygen depletion than indicated by shipboard results this difference is mainly related to non equilibrium conditions during ph measurements

overlapping regions of coseismic and transient slow slip on the hawaiian decollement abstract earthquakes and slow slip are different faulting processes that release accumulated stress on different time scales despite nearly two decades of study it is still unclear whether the same section of fault is capable of hosting both slow aseismic and fast seismic slip here we jointly invert gps strong motion records and empirically corrected tsunami waveforms for the 2018 m7 1 hawai i earthquake our inversion results suggest the earthquake had a slow rupture speed of 1 2 km s with a maximum slip of 3 m south east of the hypocenter extending to the south west through an area known to regularly host slow slip events after exploring how the choice of fault geometry and regularization parameters affect the slip distributions of the earthquake and slow slip events we find strong evidence of overlap between the two additionally we perform numerical modeling to simulate fast and slow slip behavior due to the homogeneity of the hawaiian decollement differences in effective stress are likely an important factor that causes the diversity of slip we find that an earthquake can completely penetrate into the slow slip zone provided the effective stress differences between fast and slow slip zones is large enough to facilitate this our results reinforce the idea that an individual section of fault is capable of hosting a variety of distinct slip behaviors this is important for estimating earthquake rupture extent and for better ground motion and tsunami hazard assessment

characterization of very long period seismicity accompanying summit activity at kīlauea volcano hawai i 2007 2013 abstract eruptive activity returned to the summit region of k lauea volcano hawai i with the formation of the overlook crater within the halema uma u crater in march 2008 the new crater continued to grow through episodic collapse of the crater walls and as of late 2013 had grown into an approximately elliptical opening with dimensions of 160 215 m extending to a depth of 200 m occasional weak explosive events and a persistent gas plume continued to occur through 2013 lava was first observed in the new crater in september 2008 and through 2009 the lava level remained deep in the crater and was only occasionally observed since early 2010 a lava lake with fluctuating level within the overlook crater has been nearly continuously present and has reached to within 22 m of the overlook crater rim volcanic activity at k lauea volcano is episodic at all time scales and the characterization of very long period seismicity in the band 2 100 s for the years 2007 2013 illuminates a portion of this broad spectrum of volcanic behavior three types of very long period events have been observed over this time and each is associated with distinct processes type 1 events are associated with vigorous degassing and occurred primarily between 2007 and 2009 type 2 events are associated with rockfalls onto the lava lake and occurred primarily after early 2010 both of these event types are induced by pressure and momentum changes at the top of the magma column that are transmitted downward to a source centroid 1 km below the northeast corner of the halema uma u crater where the energy couples to the solid earth at a geometrical discontinuity in the underlying dike system type 3 events are not related to surficial phenomena but are associated with transients in mass transfer that occur within the dike system very long period tremor has also accompanied the return of eruptive activity with increasing amplitude associated with hours to months long changes in gas emission rates and summit deformation

on the oxidation and burial of organic carbon in sediments of the iberian margin and nazare canyon ne atlantic abstract as a contribution to the ec omex ii program sediment carbon and nitrogen budgets are presented for the iberian margin northeastern atlantic the budgets for degradable organic carbon and associated nitrogen were calculated from sediment and pore water properties using a steady state version of a numerical coupled diagenetic model omexdia data were collected throughout the major upwelling period along five transects four of which were located on the open margin and one positioned in a major submarine canyon the nazare canyon a comparison of in situ oxygen profiles measured with monocathodic microelectrodes and with clark type microelectrodes showed that monocathodic electrodes overestimate the oxygen concentration gradient near the sediment water interface this artifact probably results from the loss in sensitivity of the monocathodic microelectrode during profiling shipboard time course measurements with clark type electrodes demonstrated transient conditions upon sediment retrieval on deck and indicated enhanced rates of oxygen consumption in the surface sediment presumably as a result of lysis or exudation of oxidisable substrates by infauna as a result oxygen fluxes calculated from shipboard oxygen profiles overestimated in situ fluxes by up to a factor of 5 for water depths 1000 m the sediments from the canyon and from a depositional area on the shelf were enriched in organic carbon 3 4 5 wt relative to the open margin stations 0 5 2 wt and showed c n ratios exceeding redfield stoichiometry for marine organic matter indicating there was deposition of organic carbon of terrestrial origin in these areas the oxidation of organic carbon on the open margin declined from 11 gcm 2 y 1 on the shelf to 2 gcm 2 y 1 at 5000 m water depth and was dominated by aerobic oxidation the reactivity of the degradable organic carbon at the time of deposition was 1 on the shelf and declined to 1 offshore the burial of refractory organic carbon at the stations along the open margin transects also declined with increasing water depth from 5 gcm 2 y 1 on the shelf to 2 y 1 at 2000 m depth whereas the burial of particulate inorganic carbon declined from 20 gcm 2 y 1 to 2 y 1 a comparison of the estimated total organic carbon deposition and predicted delivery for the shelf suggest that 58 to 165 gcm 2 y 1 is oxidized in the water column laterally advected or focused into one of the canyons anaerobic oxidation denitrification and therefore total oxidation of organic carbon was enhanced within the canyon relative to the open margin total organic carbon oxidation decreased with water depth from 22 gcm 2 y 1 at the head of the canyon to 3 gcm 2 y 1 over its fan the reactivity of the organic carbon deposited in the canyon was lower than those of the shelf stations suggesting that the canyon is being enriched in older laterally advected organic matter the burial of refractory organic carbon in sediments from the nazare canyon was considerably higher than in the sediments from the open margin it also decreased with depth from 20 gcm 2 y 1 at 343 m to 2 5 gcm 2 y 1 at 4298 m water depth the burial of particulate inorganic carbon was slightly lower than that of refractory organic carbon the burial of refractory organic carbon and the deposition of degradable organic carbon were both positively correlated with the sedimentation rates for the iberian margin and indicated burial efficiencies were 0 6 to 48 a single trend for burial efficiency versus sedimentation rate for both the canyon and the open margin indicates that the sedimentation rate was the master variable for the geographical distribution of organic carbon oxidation and carbon preservation on the nw iberian margin

a global morphology of gravity wave activity in the stratosphere revealed by the 8 year saber timed data 1 from 8 years saber timed temperature profiles between january 2002 and december 2009 we studied the activity of gravity waves in the stratosphere globally global distribution of stratospheric gravity wave potential energy was calculated from the temperature perturbations seasonal comparison of gravity wave potential energy ep shows an annual variation in middle and high latitudes and a semiannual variation in the tropics around the equator gravity wave interannual enhancements are identified just below the zonal wind zero u 0 contours corresponding to descending eastward shear phase of the qbo furthermore we provide observation evidence to support the conclusion that the deep convection is a major source for the observed tropical gravity wave activity the considerable longitude variations of largest potential energy around the equator are related not only to the specific topography and tropical convections but also to many other factors we can infer that topography and tropical deep convection are the important sources of the gravity waves in the stratosphere but the observed gravity waves in the tropical subtropical stratosphere are strongly affected by winds with different qbo phases

isotopic fractionation of oxygen and nitrogen in coastal marine sediments abstract the bulk and isotopic exchanges of o2 n2 no3 and nh4 between sediments and the overlying water benthic flux were measured at three shallow locations in puget sound using a benthic tripod oxygen consumption by the sediments averaged 4 4 mmol m 2 d 1 while n2 gas fluxes averaged 1 1 mmol m 2 d 1 the nitrogen gas flux out of the sediments was always greater than the corresponding no3 flux into the sediments indicating a large nitrification contribution to the n2 flux isotopic changes in overlying water 18o of o2 were small with an average apparent sediment respiration fractionation factor e of 3 this fractionation factor is much smaller than that measured in either the open ocean or in the laboratory the low degree of fractionation is hypothesized to occur because of the interaction of diffusive layers around reactive microsites within these sediments there was no apparent isotopic fractionation of downward diffusing no3 e 0 while the ammonium that diffused out of the sediments averaged 4 5 o heavier than both source organic matter within the sediments and overlying water no3 the large discrepancy in isotopic composition between the source organic material and nh4 can be attributed to significant isotopic fractionation of ammonium during nitrification in the oxic zone finally the 15n of n2 did not change significantly over the course of the incubations in agreement with the nitrogen isotopic budget for these sediments

pore water distribution and quantification of diffusive benthic fluxes of silicic acid nitrate and phosphate in surface sediments of the deep arabian sea benthic fluxes and pore water compositions of silicic acid nitrate and phosphate were investigated for surface sediments of the abyssal arabian sea during four cruises 1995 1998 five sites located in the northern nast western wast central cast eastern east and southern sast arabian sea were revisited during intermonsoonal periods after the ne and sw monsoon at these sites benthic fluxes of remineralized nutrients from the sediment to the bottom water of 36 106 102 350 and 4 16 mmol m 2 yr 1 were measured for nitrate silicic acid and phosphate respectively the benthic fluxes and pore water compositions showed a distinct regional pattern highest fluxes were observed in the western and northern region of the arabian sea whereas decreasing fluxes were derived towards the southeast at wast the general temporal pattern of primary production related to the ne and sw monsoon is reflected by benthic fluxes in contrast at sites nast sast cast and east a temporal pattern of fluxes in response to the monsoon is not obvious our results reveal a clear coupling between the general regional pattern of production in surface waters and the response of the benthic environment as indicated by the flux of remineralized nutrients though a spatially differing degree of decoupling during transport and remineralization of particulate organic matter and biogenic opal was observed this has to be taken into account regarding budget calculations and paleoceanographic topics

fault frictional parameters and material properties revealed by slow slip events at kilauea volcano hawai i 1 we categorize slow slip events at kilauea volcano into two distinct families based on gps measurements of the surface displacement patterns an event correlation filter confirms that eastern and western families are statistically distinguishable with the western family notably self similar the western family exhibits quasi periodicity with regular repeat times while eastern family events are aperiodic or have complicated periodicity if the decollement is the source fault for both families of events it must have varying frictional properties at the 10 km scale of separation the temporal slip and spatial scaling behavior are consistent with a simplistic rate and state dependent frictional formalism provided that the characteristic slip distance for state evolution dc is of the order of millimeters rather than the 10 100 m typically found in lab studies and the shear rigidity is around 2 gpa consistent with fault gouge material

high resolution locations of triggered earthquakes and tomographic imaging of kilauea volcano s south flank 1 the spatiotemporal patterns of seismicity beneath kilauea s south flank give insight to the structure and geometry of the decollement on which large tsunamigenic earthquakes have occurred and its relation to slow slip events sses which have been observed every 1 to 2 years since 1997 in order to record earthquakes triggered by a sse that was predicted to occur in march 2007 a temporary network of 20 seismometers was deployed on kilauea s south flank termed the seq network while the sse did not occur until 17 june 2007 theseq network recorded over 3000 earthquakes including those triggered by the sse we relocate hypocenters of volcano tectonic earthquakes and invert for p and s wave velocity structure using waveform cross correlation and double difference tomography using data from the seq network and the permanent hawaii volcano observatory network hvo data with additional data from other previous temporary arrays the best constrained hypocenters recorded by both the seq and hvo networks indicate the decollement as a subhorizontal layer of seismicity at 8 km depth less than 1 km thick in most areas with the western portion of the decollement dipping to the southeast the seismicity triggered by the june 2007 sse includes over 400 earthquakes overlapping with the southern edge of the decollement seismicity a shallower swarm of earthquakes also occurred between 2 and 7 km depth in april 2007 near apua point and may have been indirectly triggered by the mw 8 1 solomon islands earthquake at 6000 km distance which occurred 48 h prior to the beginning of the swarm

spatiotemporal evolution of dike opening and decollement slip at kīlauea volcano hawai i 1 rapid changes in ground tilt and gps positions on k lauea volcano hawai i are interpreted as resulting from a shallow two segment dike intrusion into the east rift zone that began at 1217 utc 0217 hst on 17 june 2007 and lasted almost 3 days as a result of the intrusion a very small volume of basalt about 1500 m3 erupted on 19 june northward tilt at a coastal tiltmeter subsidence of south flank gps sites southeastward displacements at southwestern flank gps sites and a swarm of flank earthquakes suggest that a slow slip event occurred on the decollement beneath k lauea s south flank concurrent with the rift intrusion we use 4 min gps positions that include estimates of time dependent tropospheric gradients and ground tilt data to study the spatial and temporal relationships between the two inferred shallow steeply dipping dike segments extending from the surface to about 2 km depth and decollement slip at 8 km depth we invert for the temporal evolution of distributed dike opening and decollement slip in independent inversions at each time step using a nonnegative least squares algorithm on the basis of these inversions the intrusion occurred in two stages that correspond spatially and temporally with concentrated rift zone seismicity the dike opening began on the western of the two segments before jumping to the eastern segment where the majority of opening accumulated dike opening preceded the start of decollement slip at an 84 confidence level the latter is indicated by the onset of northward tilt of a coastal tiltmeter displacements at southwest flank gps sites began about 18 h later and are interpreted as resulting from slow slip on the southwestern flank additional constraints on the evolution of the intrusion and decollement slip come from inversion of an envisat interferogram that spans the intrusion until 0822 utc on 18 june 2007 combined with gps and tilt data this inversion shows that up to 0822 utc on 18 june decollement slip is only required in a limited region offshore of ka ena point a similar inversion of the complete event which includes gps and tilt data up to 21 june and a second envisat interferogram spanning the complete intrusion until 21 june shows decollement slip spread westward across the south flank this may suggest westward migration of the decollement slip as the event progressed

fine scale distributions of porosity and particulate excess210pb organic carbon and caco3 in surface sediments of the deep equatorial pacific abstract sediment samples were recovered from the central equatorial pacific ocean sectioned at 1 mm intervals and analyzed for porosity organic carbon excess210pb and caco3 steep porosity gradients were measured in the upper 1 cm of the sediment column with extremely high values observed near the sediment surface similarly particulate organic carbon contents are highest at the sediment surface decrease sharply in the upper 1 cm and are relatively constant between 1 and 5 cm caco3 values on the other hand are lowest at the sediment surface and increase to a constant value below 5 10 mm depth at the carbonate ooze sites excess210pb is present throughout the upper 5 cm of the sediments suggesting relatively rapid particle mixing rates however extremely high excess210pb activities 100 dpm g are observed at the sediment surface with sharp gradients present in the upper 1 cm which would suggest slow rates of mixing this apparent contradiction along with the major features of the caco3 and particulate organic carbon profiles can be explained by a particle selective feeding mechanism in which organic carbon excess210pb enriched particles are preferentially maintained at the sediment surface via ingestion and defecation by benthic organisms

gravity wave momentum flux in the lower stratosphere over convection this work describes a method for estimating vertical fluxes of horizontal momentum carried by short horizontal scale gravity waves lambda sub x 10 100 km using aircraft measured winds in the lower stratosphere we utilize in situ wind vector and pressure altitude measurements provided by the meteorological measurement system mms on board the er 2 aircraft to compute the momentum flux vectors at the flight level above deep convection during the tropical experiment of the stratosphere troposphere exchange project step tropical data from flight 9 are presented here for illustration the vertical flux of horizontal momentum these observations points in opposite directions on either side of the location of a strong convective updraft in the cloud shield this property of internal gravity waves propagating from a central source compares favorably with previously described model results

rupture in the 4 may 2018 m w 6 9 earthquake seaward of the kilauea east rift zone fissure eruption in hawaii

modeling of alos and cosmo skymed satellite data at mt etna implications on relation between seismic activation of the pernicana fault system and volcanic unrest abstract we investigate the displacement induced by the 2 3 april 2010 seismic swarm the largest event being of ml 4 3 magnitude by means of dinsar data acquired over the volcano by the cosmo skymed and alos radar systems satellite observations combined with leveling data allowed us to perform a high resolution modeling inversion capable of fully capturing the deformation pattern and identifying the mechanism responsible for the pfs seismic activation the inversion results well explain high gradients in the radar line of sight displacements observed along the fault rupture the slip distribution model indicates that the fault was characterized by a prevailing left lateral and normal dip slip motion with no fault dilation and hence excludes that the april 2010 seismic swarm is a response to accommodate the stress change induced by magma intrusions but it is due to the tectonic loading possibly associated with sliding of the eastern flank of the volcano edifice these results provide a completely different scenario from that derived for the 22 september 2002 m3 7 earthquake along the pfs where the co seismic shear rupture was accompanied by a tensile mechanism associated with a first attempt of magma intrusion that preceded the lateral eruption occurred here a month later these two opposite cases provide hints into the behavior of the pfs between quiescence and unrest periods at etna and pose different implications for eruptive activity prediction and volcano hazard assessment the dense pattern of ground deformation provided by integration of data from short revisiting time satellite missions together with refined modeling for fault slip distribution can be exploited at different volcanic sites where the activity is controlled by volcano tectonic interaction processes for a timely evaluation of the impending hazards

geodetic evidence for en echelon dike emplacement and concurrent slow slip during the june 2007 intrusion and eruption at kīlauea volcano hawaii 1 a series of complex events at k lauea volcano hawaii 17 june to 19 june 2007 began with an intrusion in the upper east rift zone erz and culminated with a small eruption 1500 m3 surface deformation due to the intrusion was recorded in unprecedented detail by global positioning system gps and tilt networks as well as interferometric synthetic aperture radar insar data acquired by the envisat and alos satellites a joint nonlinear inversion of gps tilt and insar data yields a deflationary source beneath the summit caldera and an ene striking uniform opening dislocation with 2 m opening a dip of 80 to the south and extending from the surface to 2 km depth this simple model reasonably fits the overall pattern of deformation but significantly misfits data near the western end of an inferred dike like source three more complex dike models are tested that allow for distributed opening including 1 a dike that follows the surface trace of the active rift zone 2 a dike that follows the symmetry axis of insar deformation and 3 two en echelon dike segments beneath mapped surface cracks and newly formed steaming areas the en echelon dike model best fits near field gps and tilt data maximum opening of 2 4 m occurred on the eastern segment beneath the eruptive vent although this model represents the best fit to the erz data it still fails to explain data from a coastal tiltmeter and gps sites on k lauea s southwestern flank the southwest flank gps sites and the coastal tiltmeter exhibit deformation consistent with observations of previous slow slip events beneath k lauea s south flank but inconsistent with observations of previous intrusions slow slip events at k lauea and elsewhere are thought to occur in a transition zone between locked and stably sliding zones of a fault an inversion including slip on a basal decollement improves fit to these data and suggests a maximum of 15 cm of seaward fault motion comparable to previous slow slip events

estimation of 3 d surface displacement based on insar and deformation modeling a new approach is presented for mapping 3 d surface displacement caused by subsurface fluid volumetric change based on 1 d interferometric synthetic aperture radar insar line of sight measurements and surface deformation modeling the relationship between surface deformation and source fluid volumetric change is modeled according to elastic half space theory a distinctive advantage of the proposed approach is that it effectively extends the capability of the sun synchronous orbit side looking synthetic aperture radar that has been essentially only able to measure 1 d displacements accurately or at most 2 d displacements when insar measurements from more than one orbit or platform are combined experimental studies are carried out with both simulated and real data sets to test the performance of the method the results have demonstrated that the approach works very well

vertical axis rotation of the upper portions of the north east rift of tenerife island inferred from paleomagnetic data abstract paleomagnetic sampling sites were established in 82 dykes along an 8 km long section of the north east rift zone nerz of tenerife canary islands spain of the 70 interpretable sites 16 are of normal polarity and 54 of reversed polarity four normal polarity sites and fifteen reverse polarity sites were excluded from the grand mean calculation for statistical reasons after inverting the reverse polarity sites through the origin the in situ grand mean yields a declination d 023 8 an inclination i 42 3 95 3 2 39 0 n 51 that is discordant to the expected late miocene to pleistocene field direction d 357 6 i 38 8 95 4 7 this discordance can be explained as either a 26 clockwise vertical axis rotation or a 28 wnw side down tilt about an average 009 horizontal tilt axis the sampled section is composed of numerous semi vertical dykes cutting mainly lava flow units that are sub horizontal and cross cut by steeply dipping faults 70 90 field evidence is therefore more compatible with a vertical axis rotation rather than a horizontal axis tilt of the drilled units we argue that this clockwise vertical axis rotation is likely related to strike slip movements that occurred along the edges of the collapse scars and accommodate the emplacement and growth of the underlying intrusive core and associated dykes six new 40ar 39ar age determinations constrain the main interval of dyke emplacement within the nerz between 0 99 ma and 0 56 ma the intrusive activity in the sampled section of the rift appears to have been almost continuous with several intrusion pulses that are probably related to flank destabilisation event s during the mid pleistocene our study thus demonstrates a long lived multi faceted history that shaped the nerz