two mode ionospheric response and rayleigh wave group velocity distribution reckoned from gps measurement following mw 7 8 nepal earthquake on 25 april 2015 the coseismic induced ionospheric total electron content tec perturbations were analyzed following the mw 7 8 nepal earthquake 28 147 n 84 708 e depth 15 km that occurred on 25 april 2015 at 06 11 26 utc the ionospheric response is due to both the modes i e shock acoustic waves slow mode and rayleigh wave induced fast mode the continuous global positioning system gps data at about 60 sites from various gps networks have been used in the present study all the sites within epicentral distance of 2400 km and 70 170 azimuth recorded the rayleigh wave induced tec response while the sites within 400 2200 km in the same azimuth recorded the response from both the modes the maximum coseismic induced peak to peak tec amplitude is 1 2 total electron content unit 1 tecu 1016 el m 2 from hodochron plot the apparent rayleigh wave velocity has been determined as 2400 m s on the average and the acoustic wave velocity as 1180 m s both these waves being discernible beyond 1200 km of epicentral distance as also evident from hodochron plot and wavelet spectrographs we reckoned the rayleigh wave group velocities using ionospheric response at selected radial pairs of stations and validated the ionospheric response distribution seen mainly depending on the epicentral distance satellite geometry directivity of radiation pattern and the upper crustal heterogeneity this study highlights the characteristics of ionospheric response consequent to the 2015 nepal earthquake

unzipping long valley an explanation for vent migration patterns during an elliptical ring fracture eruption long valley caldera california formed during the cataclysmic pleistocene eruption of the bishop tuff previous stratigraphic and petrologic studies of this eruption deciphered an intriguing pattern of vent migration thought to mirror the lateral propagation unzipping of magma tapping ring fractures during caldera collapse from scaled analog models we show that this unzipping pattern was intrinsically related to the high plan view ellipticity of the precollapse magma chamber roof we also provide a first order kinematic explanation for the systematic location of initial elliptical roof failure and for the lateral propagation of highly elliptical ring fractures

curie isotherm depth from aeromagnetic data constraining shallow heat source depths in the central aeolian ridge southern tyrrhenian sea italy the salina lipari and vulcano volcanic ridge and the surrounding sea sectors aeolian archipelago southern tyrrhenian sea italy are characterized by vents responsible for a recent 40 ka 1889 1890 ad effusive and explosive subareal activity and repeated 56 to 7 ka in age submarine explosive eruptions from source areas located between lipari and vulcano a spectral depth estimation of the magnetic bottom using a fractal method on aeromagnetic data from vulcano lipari and salina volcanic ridge allows us to constrain the curie isotherm depth the elevated portion of the isotherm is between 2 and 3 km below salina and vulcano and about 1 km below lipari the curie depth results in the context of other geological and geophysical evidence suggest that the rise of the curie isotherm is mainly due to the occurrence of shallow heat sources such as magma ponds and associated hydrothermal systems the short wavelength magnetic anomaly field reflects magnetic contrasts from highly magnetized volcanic bodies low magnetization sediments and hydrothermally altered rocks borehole temperature data verify the curie temperature derived from the magnetic methods on the island of vulcano we conclude that the whole vulcano lipari and salina volcanic ridge is active and should be monitored

dike fault interaction during the 2004 dallol intrusion at the northern edge of the erta ale ridge afar ethiopia received 17 july 2012 revised 29 august 2012 accepted 4 september 2012 published 12 october 2012 1 during continental rifting the interaction between faulting and magmatic intrusions is not well understood using insar and seismicity we show that a 0 06 km 3 dike was intruded along the dallol segment ethiopia and was accompanied by a mw 5 5 earthquake and associated fault slip along the western flank of the rift the intrusion was fed by a previously unidentified magma chamber under dallol the total seismic moment release was 2 3 10 17 nm 10 of the geodetic moment this is a higher proportion than during the 2005 2009 dabbahu rifting episode which ranged between 1 4 of the geodetic moment a larger component of faulting occurs at dallol than at dabbahu segment a feature we interpret to be related to the proximity 10 km of the dallol segment to the rift margin where welldeveloped faults facilitate slip citation nobile a c pagli d keir t j wright a ayele j ruch and v acocella 2012 dike fault interaction during the 2004 dallol intrusion at the northern edge of the erta ale ridge afar ethiopia geophys res lett 39 l19305 doi 10 1029 2012gl053152

imaging and modeling the ionospheric airglow response over hawaii to the tsunami generated by the tohoku earthquake of 11 march 2011 1 although only centimeters in amplitude over the open ocean tsunamis can generate appreciable wave amplitudes in the upper atmosphere including the naturally occurring chemiluminescent airglow layers due to the exponential decrease in density with altitude here we present the first observation of the airglow tsunami signature resulting from the 11 march 2011 tohoku earthquake off the eastern coast of japan these images are taken using a wide angle camera system located at the top of the haleakala volcano on maui hawaii they are correlated with gps measurements of the total electron content from hawaii gps stations and the jason 1 satellite we find waves propagating in the airglow layer from the direction of the earthquake epicenter with a velocity that matches that of the ocean tsunami the first ionospheric signature precedes the modeled ocean tsunami generated by the main shock by approximately one hour these results demonstrate the utility of monitoring the earth s airglow layers for tsunami detection and early warning

a new crater near insight implications for seismic impact detectability on mars a new 1 5 m diameter impact crater was discovered on mars only 40 km from the insight lander context camera images constrained its formation between 21 february and 6 april 2019 follow up high resolution imaging science experiment images resolved the crater during this time period three seismic events were identified in insight data we derive expected seismic signal characteristics and use them to evaluate each of the seismic events however none of them can definitively be associated with this source atmospheric perturbations are generally expected to be generated during impacts however in this case no signal could be identified as related to the known impact using scaling relationships based on the terrestrial and lunar analogs and numerical modeling we predict the amplitude peak frequency and duration of the seismic signal that would have emanated from this impact the predicted amplitude falls near the lowest levels of the measured seismometer noise for the predicted frequency hence it is not surprising this impact event was not positively identified in the seismic data finding this crater was a lucky event as its formation this close to insight has a probability of only 0 2 and the odds of capturing it in before and after images are extremely low we revisit impact seismic discriminators in light of real experience with a seismometer on the martian surface using measured noise of the instrument we revise our previous prediction of seismic impact detections downward from a few to tens to just 2 per earth year still with an order of magnitude uncertainty

segmented lateral dyke growth in a rifting event at barðarbunga volcanic system iceland crust at many divergent plate boundaries forms primarily by the injection of vertical sheet like dykes some tens of kilometres long1 previous models of rifting events indicate either lateral dyke growth away from a feeding source with propagation rates decreasing as the dyke lengthens2 3 4 or magma flowing vertically into dykes from an underlying source5 6 with the role of topography on the evolution of lateral dykes not clear here we show how a recent segmented dyke intrusion in the bar arbunga volcanic system grew laterally for more than 45 kilometres at a variable rate with topography influencing the direction of propagation barriers at the ends of each segment were overcome by the build up of pressure in the dyke end then a new segment formed and dyke lengthening temporarily peaked the dyke evolution which occurred primarily over 14 days was revealed by propagating seismicity ground deformation mapped by global positioning system gps interferometric analysis of satellite radar images insar and graben formation the strike of the dyke segments varies from an initially radial direction away from the bar arbunga caldera towards alignment with that expected from regional stress at the distal end a model minimizing the combined strain and gravitational potential energy explains the propagation path dyke opening and seismicity focused at the most distal segment at any given time and were simultaneous with magma source deflation and slow collapse at the bar arbunga caldera accompanied by a series of magnitude m 5 earthquakes dyke growth was slowed down by an effusive fissure eruption near the end of the dyke lateral dyke growth with segment barrier breaking by pressure build up in the dyke distal end explains how focused upwelling of magma under central volcanoes is effectively redistributed over long distances to create new upper crust at divergent plate boundaries

harmonic excitation of mantle rayleigh waves by the 1991 eruption of mount pinatubo philippines an unusually long at least two hours seismic wave train having periods of about 230 sec was recorded at many worldwide seismic stations during the major eruption of mount pinatubo in the philippines on june 15 1991 this wave train exhibits two sharp spectral peaks at 228 and 270 sec the group velocity phase velocity and the particle motion of this wave train indicate that it is a rayleigh wave the most probable excitation mechanism is acoustic coupling of atmospheric oscillations that were set off by continuous thermal energy flux from the volcano the two spectral peaks correspond to the characteristic periods of acoustic and gravity modes of the earth s atmosphere the magnitude of the vertical single force equivalent to the acoustic coupling is 1 6 10 17 dynes over a frequency band of 0 003 to 0 01 hz the results suggest the possibility of using acoustically coupled rayleigh waves for detection characterization and quantification of volcanic eruptions acoustic coupling of the atmosphere and the solid earth provides a unique seismic source with long duration

origin and accumulation of trace elements in sediments of the northwestern mediterranean margin continental margins receive natural and anthropogenic trace elements tes from direct atmospheric deposition of aerosols onto the sea surface and from advection of riverine suspended particles and or resuspended sediments from the continental shelf slope when the margin is incised by submarine canyons as for example in the northwestern mediterranean sea most of these particles are preferentially transferred via these topographic features towards their final repositories in the abyssal plain the gulf of lions gol shelf receives the largest particulate riverine input to the western mediterranean with its associated chemical contaminants originating from the industrialized and urbanized rhone valley sediments samples grabs cores and moored traps collected in the cap de creus cdc canyon and its adjacent areas at the southwestern exit of the gol were analyzed to explore the origin dispersion transfer and accumulation of a suite of tes ag cd co cr cu ni pb zn and v from the gol shelf to the adjacent continental rise distributions of cu cr ni pb zn and v in the surface sediments of the shelf confirm their terrigenous origin in association with clay minerals whereas ag and cd are more associated with organic matter om all these tes are anthropogenically enriched in the rhone prodelta sediments anthropogenic influence remains clearly discernible in the gol shelf surface sediments for ag pb and zn hydrodynamical resuspension and sorting of shelf sediments occur at the head of the cdc canyon during dense shelf water cascading events during these events the material collected in moored sediment traps contains a higher coarse carbonate fraction slightly impoverished in tes compared to the clays of the nepheloid layer and the organically rich particles deposited before and at the end of the cascading period upper and middle canyon sediments are characterized by high sedimentation rates 0 2 cm yr 1 of fine clay material conversely sediments from the lower continental slope and rise exhibit low sedimentation rates 0 06 cm yr 1 and receive carbonaceous planktonic detritus from the water column at the lower continental slope coarse material includes foraminifers and pteropods whereas at the continental rise finer planktonic derived material is more abundant both in the cdc canyon and in its adjacent lower continental slope rise sediments co cu cr ni and v are associated with clay whereas ag cu and pb are preferentially associated with om cadmium cr and zn are also associated with om in canyon sediments carbonaceous plankton appears to be especially efficient for scavenging ag

new unspiked k ar ages of volcanic rocks of the central and western sector of the aeolian islands reconstruction of the volcanic stages abstract a geochronological study of the filicudi salina lipari and vulcano islands aeolian archipelago using the unspiked potassium argon technique provides new age data which combined with stratigraphic correlation better constrain the temporal evolution of volcanism the unspiked k ar age of the oldest exposed lavas on filicudi 219 5 ka is significantly younger than the previous estimation of 1 02 ma in the general context of aeolian volcanism this new date suggests that the volcanism of the western sector of the aeolian archipelago is younger than previously thought geochronological data point out on the rapid transition from calc alkaline to potassic volcanism the distribution of the k ar ages within the salina lipari vulcano group shows that the volcanism started on lipari and propagated over time northward on salina and southward on vulcano geochronological and geophysical data suggest that the onset of volcanism in the central sector of the aeolian arc may be due to a mantle upwelling structure located below lipari a change in the style of the eruptions occurred in the salina lipari vulcano system at about 100 ka from the present low energy magmatic eruptions occurred between 188 and about 100 ka from about 100 ka to the present higher energy eruptions and low energy events due to magma water interaction also occurred this change in the style of activity together with the appearance of evolved products i e rhyolites during the last 50 ka is consistent with the formation of magmatic reservoirs located at shallower depth with respect to those of the 188 100 ka period the new geochronological data and available petrological models reveal that a change in the deep source of the primary magmas occurred in a relatively short time interval

observation and modeling of the winter coastal oceanic circulation in the gulf of lion under wind conditions influenced by the continental orography fetch experiment fluxes surfaces waves remote sensing and ocean circulation in the north mediterranean sea results from the fetch experiment 1 hydrological and currentmeter observations were collected on the continental shelf and slope of the gulf of lion during the fetch experiment 13 march to 15 april 1998 results from the first part of the cruise characterized by strong northern winds are presented the hydrological structures evidence well mixed water masses on the eastern and western ends of the shelf in the central part the situation is more complex with the influence of the rhone river s freshwater plume in the first 40 m of the water column and closer from the bottom with the confrontation of downwelled coastal cold water and upwelled warmer and saltier slope water current measurements show the path of the cyclonic circulation along the slope which is part of the general circulation of the western mediterranean and suggest the presence of large and temporary eddies on the shelf this oceanic circulation is simulated with a free surface three dimensional model using realistic forcing the model outputs are in agreement with the main hydrological and circulation patterns the results further indicate that coastal eddies are generated by the mesoscale structure of the wind field

three dimensional ionospheric tomography of post seismic perturbations produced by the denali earthquake from gps data summary the coupling between the solid earth and its atmosphere is responsible for vertically propagating infrasonic waves generated by seismic surface waves these pressure waves are amplified as they propagate upward and produce perturbations of ionospheric electron density the electron density perturbations above california due to the seismic surface waves generated by the denali earthquake on 2002 november 3 have been imaged from gps data by a tomographic method the integrated electron content along gps ray paths presents a noise level that is lower in the acoustic wave frequency band than in the gravity wave frequency band therefore the filtered gps data from californian networks are inverted for a tomographic reconstruction of electron density perturbations in the acoustic frequency band the inversion is properly resolved only in a small number of areas due to the geometry of gps ray paths in these areas a wave propagating upward at 1 2 0 3 km s 1 and horizontally at 4 1 km s 1 is observed with a timing consistent with an infrasonic wave generated by the path of seismic surface waves the discrepancies between the observed electron density perturbation structure and the expected infrasonic wave can be explained by the poor resolution of the inverse problem or by a simple model of interactions between the neutral wave and the plasma future development of dense gps networks and the advent of the galileo system will overcome the resolution problems and allow us to relate ionospheric perturbations to the seismic signal such a relation can be used to constrain the source and propagation of seismic waves as well as upper atmosphere characteristics

goce the first seismometer in orbit around the earth the first in situ sounding of a post seismic infrasound wavefront is presented using data from the goce mission the atmospheric infrasounds following the great tohoku earthquake on 11 march 2011 induce variations of air density and vertical acceleration of the goce platform these signals are detected at two positions along the goce orbit corresponding to a crossing and a doubling of the infrasonic wavefront created by seismic surface waves perturbations up to 11 of air density and 1 35 10 7 m s2 of vertical acceleration are observed and modeled with two different solid atmosphere coupling codes these perturbations are a due to acoustic waves creating vertical velocities up to 130 m s amplitudes and arrival times of these perturbations are reproduced respectively within a factor 2 and within a 60 s time window waveforms present a good agreement with observed data the vertical acceleration to air density perturbation ratio is higher for these acoustic waves than for gravity waves combining these two pieces of information offers a new way to distinguish between these two wave types this new type of data is a benchmark for the models of solid atmosphere coupling amplitude and frequency content constrain the infrasound attenuation related to atmosphere viscosity and thermal conductivity observed time shifts between data and synthetics are ascribed to lateral variations of the seismic and atmospheric sound velocities and to the influence of atmospheric winds these effects should be included in future modeling this validation of our modeling tools allows to specify more precisely future observation projects

rapid and widespread dispersal of flood sediment on the northern california margin the dispersal of flood sediment from small river systems is a poorly studied yet potentially important aspect of active continental margin sedimentation in january 1995 during a flood with a 30 yr return period the eel river northern california delivered an estimated 25 3 106 t metric tons of fine grained 62 m sediment to the ocean the flood formed a distinct layer on the sea bed that was centered on the 70 m isobath extended for 30 km along shelf and 8 km across shelf and was as thick as 8 5 cm but contained only 6 106 t of sediment thus 75 of the flood derived sediment did not form a recognizable deposit but was instead rapidly and widely dispersed over the continental margin stratigraphic models of and compilations of sediment flux to active continental margins need to take the dispersive nature of small river systems into account

detecting atmospheric perturbations produced by venus quakes 1 the possibility to detect seismic activity on venus by using the mechanical coupling of the solid atmosphere system is investigated first the atmospheric attenuation of infrasonic waves produced by quakes is theoretically determined from a pure co2 atmospheric model demonstrating that frequencies below 0 1 hz are amplified by a factor of 10 000 above 120 km altitude with a simple quake model an upper limit of infrasonic adiabatic temperature and density perturbations above the source is estimated then we demonstrate that the temperature increase due to high altitude acoustic energy dissipation above a quake is large enough to be measured by remote sensing methods finally the expected post seismic effects are analyzed in the framework of the virtis instrument on board the esa venus express mission

from sumatra 2004 to tohoku oki 2011 the systematic gps detection of the ionospheric signature induced by tsunamigenic earthquakes the recent tsunamigenic earthquake in tohoku 11 march 2011 strongly affirms one more time after the sumatra event 26 december 2004 the necessity to open new paradigms in oceanic monitoring detection of ionospheric anomalies following the sumatra tsunami demonstrated that ionosphere is sensitive to the tsunami propagation observations supported by modeling proved that tsunamigenic ionospheric anomalies are deterministic and reproducible by numerical modeling via the ocean neutral atmosphere ionosphere coupling mechanism in essence tsunami induces internal gravity waves propagating within the neutral atmosphere and detectable in the ionosphere most of the ionospheric anomalies produced by tsunamis were observed in the far field where the tsunami signature in the ionosphere is clearly identifiable in this work we highlight the early signature in the ionosphere produced by tsunamigenic earthquakes and observed by gps measuring the total electron content close to the epicenter we focus on the first hour after the seismic rupture we demonstrate that acoustic gravity waves generated at the epicenter by the direct vertical displacement of the source rupture and the gravity wave coupled with the tsunami can be discriminated with theoretical support we illustrate the systematic nature of those perturbations showing several observations nominally the ionospheric perturbation following the tsunamigenic earthquakes in sumatra on 26 december 2004 and 12 september 2007 in chile on 14 november 2007 in samoa on 29 september 2009 and the recent catastrophic tohoku oki event on 11 march 2011 based on the analytical description we provide tracks for further modeling efforts and clues for the interpretation of complex and thus often misleading observations the routine detection of the early ionospheric anomalies following the rupture highlights the role of ionospheric sounding in the future ocean monitoring and tsunami detection

ionospheric remote sensing of the denali earthquake rayleigh surface waves 1 using the global positioning system we have detected ionospheric disturbances associated with the long period rayleigh waves from the 2002 denali earthquake ms 7 9 the dense california gps networks allowed us to map the ionospheric perturbations and to compute the group velocity with a high spatial resolution above the pacific coasts due to a low sampling rate a large error in the velocity determination remains nonetheless it demonstrates that bi static remote sensing measurements of seismic waves with gps networks can be performed monostatic measurements with a dedicated satellite could possibly be used to record in the ionosphere surface waves originating from large earthquakes such a space based remote sensing of the local group velocity of rayleigh surface waves would effectively complement the seismic networks for high resolution global tomography of the earth s lithosphere

morphological changes and sedimentary processes induced by the december 2003 flood event at the present mouth of the grand rhone river southern france the study which is based on repetitive bathymetric surveys assesses changes and effects of one of the most important floods recorded in the rhone delta area bottom morphology and sediment distribution in the rhone outlet after the december 2003 flood are discussed by comparison between digital terrain maps dtms of november 2003 and january 2004 the post flood morphology shows that the whole of the system is active mainly in the east the channel of the rhone has been hollowed out on the left bank by more than 5 m the eastern coast of the mouth has retreated 400 m the mouth bar has prograded 200 m and the slope of the delta front has increased by 0 19 the overlay of pre and post flood dtms makes it possible to estimate the total volume deposited in the 0 to 20 m zone as 7 8 10 the acquisition of bathymetric measurements immediately before and after a major flood allows more than a simple morphological description in addition an analysis of the solid load transfer processes towards the prodelta is achievable three mechanisms are highlighted most of the material eroded in the channel and supplied to the delta front corresponds to fine sediment that drape homogeneously over the pre flood morphology of the delta front the transit of the coarsest sediment primarily sand is slowed down in the channel of the rhone this sediment builds up in relatively small areas leading to the formation of gullies on the prodelta slope the gullies have fixed positions and disappear gradually towards the west following the progressive migration of the active band towards the east these old features are not reactivated by floods occurring after their formation during the flood only a small volume of coarse sediment bypasses through the gullies and the fine deposits are remobilised rapidly or compacted flood input concerns essentially the delta front which traps 90 of the fluvial solid discharge between 0 and 20 m depth the coarse prodelta supply is then due mainly to mass movements of unconsolidated material deposited beforehand on the top of the delta front consequently the main nourishment of the prodelta does not occur directly during and or immediately after a flood event but is delayed by sediment being temporarily trapped on the delta front

sediment dynamics during wet and dry storm events on the tet inner shelf sw gulf of lions abstract the importance of short term processes such as floods and storms on sediment delivery and reworking on the tet inner shelf was investigated the tet inner shelf is a small event dominated system located in the south western part of the gulf of lions the expected sedimentary scenario in this environment is that fluvial sediment should be deposited on the prodelta and later dispersed around the shelf and slope by wave and current reworking during storms this paper investigates differences in inner shelf sediment dynamics between storm events occurring during usual river discharges and those occurring during river floods waves current velocities near bottom water turbidity bottom sediment grain size and sea floor erosion accretion were concurrently measured at 28 m water depth on the tet inner shelf from november 2003 to march 2004 two major storms took place on 4 december 2003 and 21 february 2004 and two moderate storms occurred on 8 december 2003 and 14 march 2004 the two major storms displayed similar wave characteristics maximum significant wave height h s 7 m peak period t p 12 s and wave direction around 90 the main environmental differences during the two major storm events correspond to the amount of sediment discharged from the tet river about 2 10 4 t of sediment was delivered by the river during the 4 december flood wet storm and less than 5 10 2 t during the 21 february storm dry storm sediment dynamics were quite similar during the storm events resuspension caused by waves and sediment advection towards the southeast due to near bottom shelf currents were the dominant sedimentary processes the result was a bottom sediment erosion of several centimetres at the study site during both the wet and dry events the main differences between the wet and dry events arose after the storm immediately after the peak of the wet storm sediment supplied by the tet river and probably from other rivers was deposited around the river mouth a few days later during a moderate storm this unconsolidated sediment was resuspended transported offshore and deposited on the inner shelf in contrast a moderate storm which occurred some days after the dry february storm caused bottom erosion on the inner shelf because no fresh sediment was available on the shallower area the results from this study indicate that the tet inner shelf at 28 m water depth is mainly a bypass zone for sediment that is transported s se towards the middle outer shelf and slope although ephemeral sediment deposits may be favoured by the sediment supplied from flood events sediment transport across the shelf from the river to the slope follows a complex multi step pattern that needs to be addressed using a multi event approach

infrasound and gravity waves over the andes observed by a pressure sensor on board a stratospheric balloon the study of infrasound acoustic and gravity waves sources and propagation in the atmosphere of a planet gives us precious insight on atmosphere dynamics climate and even internal structure the implementation of modern pressure sensors with high rate sampling on stratospheric balloons is improving their study we analyzed the data from the national aeronautics and space administration ultra long duration balloon mission 16 may to 30 june 2016 here we focus on the balloon s transit of the andes mountains we detected gravity waves that are associated to troposphere convective activity and mountain waves an increase of the horizontal wavelengths from 50 to 70 km with increasing distance to the mountains is favoring the presence of mountain waves we also report on the detection of infrasounds generated by the mountains in the 0 01 0 1 hz range with a pressure amplitude increase by a factor 2 relative background signal besides we characterized the decrease of microbaroms power when the balloon was flying away from the ocean coast these observations suggest in a way similar to microseisms for seismometers that microbaroms are the main background noise sources recorded in the stratosphere even far from the ocean sources finally we observed a broadband signal above the andes between 0 45 and 2 hz probably associated with a thunderstorm the diversity of geophysical phenomena captured in less than a day of observation stresses the interest of high rate pressure sensors on board long duration balloon missions

transport and depositional process of soil organic matter during wet and dry storms on the tet inner shelf nw mediterranean article i nfo river floods and storm waves are major processes for the dispersal and deposition of terrestrial organic matter om in river dominated coastal areas a wet storm is connected to a flood with a high river discharge while a dry storm is not associated with a flood to better understand the sedimentation dynamics of terrestrial om especially soil om at the land ocean interface during wet and dry storms we studied sediment trap and core material collected on the tet inner shelf nw mediterranean using multiple organic proxies in combination with hydrodynamic parameters the proportion of soil om to the total om in the trap material calculated based on the bit branched and isoprenoid tetraether index was higher during both wet 40 and dry 30 storms than during non storm periods 10 however only surface sediments 1 cm thick layers recovered after december wet and moderate storms in 2003 showed enhanced soil om percentages compared to the deeper sediments deposited during the last century given that the wet storm eroded 4 cm of seabed at the study site flood induced fresh soil om was not deposited on the tet inner shelf during the wet storm however the following moderate storm caused resuspension of flood associated soil om which was previously trapped nearshore accordingly soil om was transported to the tet inner shelf and stored there until the dry storm occurred

modern accumulation rates and a sediment budget for the eel shelf a flood dominated depositional environment the northern california continental margin is periodically impacted by geologically significant storms which have a marked influence on terrigenous sediment supply flood deposition and long term accumulation of fine grained sediment on the eel shelf accumulation of eel river muds on the adjacent shelf was investigated using 210pb and 137cs geochronologies in order to understand the fate of sediment discharged by the eel river and to relate patterns of net sediment accumulation 100 yr time scale to sediment dynamics 210pb data demonstrate that modern accumulation of river mud occurs from the 50 m isobath seaward across shelf accumulation rates decrease from maximum mid shelf values of 0 6 1 7 g cm 2 yr 1 to values of 0 2 0 4 g cm 2 yr 1 at the shelf break with a spatially weighted mean of 0 5 g cm 2 yr 1 0 4 cm yr for the entire shelf 210pbxs sediment depth profiles from the region of highest accumulation rate are characterized by subsurface intervals of low and uniform activity which are produced by flood deposition in some cores particular 210pbxs activity intervals may be associated with major eel river floods of 1955 1964 and 1974 it is postulated that because of the coincidence of high river flow events and southerly winds during cyclonic winter storms net northward transport allows for preferential deposition of fine grained sediment north of the river mouth over the past 100 years fluvial sediment input combined with marine dispersal processes have produced a mid shelf depocenter evident by both the spatial distribution of 210pb accumulation rates and by clay rich flood layers partially preserved in shelf deposits a fine grained sediment budget for the dispersal system based on hydrological data and 210pb geochronologies demonstrates that a maximum of 20 3 109 kg yr of the mean annual supply of fluvial mud 14 109 kg yr is trapped on the shelf the results of this study demonstrate that 1 short term sedimentation processes associated with floods can influence sediment accumulation on longer time scales and 2 a major fraction of fine grained sediment supplied to tectonically active margins by flood prone mountainous rivers bypasses narrow continental shelves

dike induced faulting in rift zones of iceland and afar geodetic data and field observations demonstrate that the emplacement of dikes in volcanic rift zones frequently generates normal faulting and graben subsidence at the earth9s surface elastic modeling of the vertical ground surface displacements above dikes and faults indicates that the extent of graben subsidence can be achieved only if fault slip extends virtually to or beyond the dike plane at depth a mechanical model that includes dikes and frictional faults shows that dike opening tends to compress and lock faults located to either side of the dike therefore slip extending into or beyond the dike cavity must occur either 1 on faults that intersect the dike near its top above the zone of dike induced compression or 2 on faults that slip ahead of the dike as it propagates laterally data from iceland indicate that slip occurred on deep faults that presumably slipped in advance of the laterally propagating dike

small rivers contribution to the quaternary evolution of a mediterranean littoral system the western gulf of lion france abstract along the mediterranean coasts and the atlantic french coast former and actual research programs focused on major river systems estuaries and deltas characterized by a last glacial relative sea level lowstand and incision and a well developed sedimentary incised valley infilling deposited during the following sea level rise and highstand this paper presents the preliminary results of a program focused on a particular area of the gulf of lion coast with a thin sedimentary cover over the substratum and only minor rivers with non apparent and important sedimentary contribution during the late quaternary the results show that in this area the best pliocene to actual sedimentary record is preserved the paper rests on the analysis of an extensive database of recent high resolution and very high resolution seismic reflection lines and previously published core data seismic data show that a major complex of paleovalleys connected with the orb aude and agly rivers is preserved on the inner shelf and adjacent coastal plain on the inner shelf the separated incised valleys merged in a unique broad and shoreparallel incision dipping southward at the southward extremity the incision turns eastward and seaward the basal surface of this incision extends seawards under six to seven late quaternary depositional sequences preserved on the mid and outer shelf the infilling of the complex of paleovalleys is characterized by aggrading deposits attributed to periods of relative sea level rise transgressive systems tracts organized into several subunits bounded by internal discontinuities locally deeply incising the discontinuities are amalgamated surfaces including successive sequence boundaries indicative of phases of relative sea level falls merged with transgressive surfaces indistinct tidal and wave ravinement surfaces the subunits are the part of late quaternary depositional sequences preserved in estuarine environments they are the lateral equivalents of landward fluvial terraces and seaward coastal and prodeltaic deposits on the shelf using borehole dataset the underlying and eroded deposits below the basal unconformity are correlated with pliocene deposits outcropping landward in the hinterland the top of the incised valleys complex is capped by the last glacial lowstand surface of erosion 18 ky b p reworked by the postglacial transgressive surface ts dissociated near the shoreline into a tidal and a wave ravinement surfaces above the ts the very high resolution vhr seismic data in the lagoons the tidal channels and cores reveal in details the stratigraphic architecture of the deposits at the base a small wedge constitutes the postglacial transgressive systems tract tst locally thinning in the areas distant of the sediment point sources the tst is capped by a flat surface of wave reworking maximum flooding surface or mfs prolongating under the leucate lagoon and merging offshore at the seafloor boreholes and vhr seismic lines trough the coastal barrier and in the lagoon show that the shoreline probably migrated far landward at the end of the transgression when the rate of sea level rise decreased strongly the shoreline migrated seaward and prograding and aggrading sandy material with landward muddy lateral equivalent facies deposited early highstand systems tract hst above the mfs offshore fine material deposited as a sigmoidal blanket of mud originating in part from the north east and rhone river under oceanic circulation equivalent to a subaqueous prodelta subsequently the modern beach barrier built up by wave reworking of the early hst this new study of the western part of the gulf of lion inner shelf and littoral illustrates an incised valley complex and thus presents the best preserved example of the sedimentary record of the effects of the relative sea level changes during the pliocene to actual period for the first time the land to sea transition is preserved and the late quaternary depositional sequences are in a great part observed the last post glacial deposits present a simplified but very different organisation compared to a record front of the adjacent rhone river consequently a synthesis is now possible

improved general circulation models of the martian atmosphere from the surface to above 80 km we describe a set of two new generation general circulation models of the martian atmosphere derived from the models we originally developed in the early 1990s the two new models share the same physical parameterizations but use two complementary numerical methods to solve the atmospheric dynamic equations the vertical resolution near the surface has been refined and the vertical domain has been extended to above 80 km these changes are accompanied by the inclusion of state of the art parameterizations to better simulate the dynamical and physical processes near the surface boundary layer scheme subgrid scale topography parameterization etc and at high altitude gravity wave drag in addition radiative transfer calculations and the representation of polar processes have been significantly improved we present some examples of zonal mean fields from simulations using the model at several seasons one relatively novel aspect previously introduced by wilson 1997 is that around northern winter solstice the strong pole to pole diabatic forcing creates a quasi global angular momentum conserving hadley cell which has no terrestrial equivalent within such a cell the coriolis forces accelerate the winter meridional flow toward the pole and induce a strong warming of the middle polar atmosphere down to 25 km this winter polar warming had been observed but not properly modeled until recently in fact thermal inversions are generally predicted above one and often both poles around 60 70 km however the mars middle atmosphere above 40 km is found to be very model sensitive and thus difficult to simulate accurately in the absence of observations

geomorphic tectonic control of sediment discharge to the ocean the importance of small mountainous rivers analysis of data from 280 rivers discharging to the ocean indicates that sediment loads yields are a log linear function of basin area and maximum elevation of the river basin other factors controlling sediment discharge e g climate runoff appear to have secondary importance a notable exception is the influence of human activity climate and geology on the rivers draining southern asia and oceania sediment fluxes from small mountainous rivers many of which discharge directly onto active margins e g western south and north america and most high standing oceanic islands have been greatly underestimated in previous global sediment budgets perhaps by as much as a factor of three in contrast sediment fluxes to the ocean from large rivers nearly all of which discharge onto passive margins or marginal seas have been overestimated as some of the sediment load is subaerially sequestered in subsiding deltas before the proliferation of dam construction in the latter half of this century rivers

shoreface migrations at the shelf edge and sea level changes around the last glacial maximum gulf of lions nw mediterranean the bourcart herault canyon interfluve in the gulf of lions nw mediterranean was the site of very high sedimentation up to 2 5 m kyr around the last glacial maximum due to the vicinity of major fluvial systems that fed the shelf edge shoreface deposits and offshore muds deposited during each glacial interglacial 100 kyr cycle created a repeated motif with high angle and low angle clinoforms on seismic profiles new detailed morphological sedimentological and paleo environmental data constrained by 14c dating allow us to propose a scenario for the evolution of this critical area between 46 and 15 cal kyr bp the major seismic sequence s5 formed as a forced regression during the overall sea level fall between mis 3 and mis 2 can be sub divided into several prograding units which indicate that relative sea level changes were punctuated by intervals of increased fall or slow down or even stillstand similarly the onset of sea level rise was marked by steps during which wave cut terraces formed and can be tracked all around the gulf of lions three stillstands or slow downs of sea level change are identified and dated by deposits found at 90 m relative sea level 21 cal kyr bp 110 115 m rsl 18 17 cal kyr bp and 98 105 m rsl before 15 9 cal kyr bp cementation of beach rocks that now form eroded pinnacles culminating at 90 m occurred during the 21 kyr stillstand the position of relative sea level during the maximum lowstand is not known but should be deeper than 115 m periods of increased northwesterly winds favoured transport of coarser sediment at the shelf edge in relation with deep water cascading this created a distinct sandy interval during the period of heinrich event 2 around 24 cal kyr bp at the origin of amplitude anomaly on very high resolution seismic data the increased sea level rise around 15 cal kyr bp resulted in an abrupt decrease of sedimentation

a 2000 yr record of sacramento san joaquin river inflow to san francisco bay estuary california oxygen and carbon isotopic measurements of fossil bivalves macoma naarfa contained in estuarine sediment are used to reconstruct a late llolocene record of sitlinity and stream flow in san francisco bay discharge into the bay is a particularly good indicator of paleoclin ate in california because the bay s influent streams drain 40 of the state the isotopic record suggests that hetween al oul 1670 ant1 1900 calcnd r yc trs yr cal 1i i inflow to the bay was sul stantially greirler tlian the cstinli tecl precliversion inllow ol 1100 m3 s an unconforn ity representing a 900 yr hiatus is present in the core between 1670 ancl 750 yr cirl ii 13 possil ly r lusc cl by i n tjor 11ydrologic rl event over the p ist 750 yr strcitn ilow to s iii i ril cisco ikty ii is vitrirtl wit11 i pcriotl ol 200 yr i1lter11itte wet iltttl tlry i tlrougl t intc r rls typiritlly 11 rvc i lstecl 40 to 100 yr

formation of the aude orb and herault prodeltas and their characterisation using physicochemical and sedimentological parameters abstract the formation of mediterranean prodeltas depends on microtidal estuarine dynamics the study of the aude estuary and others shows the usual presence of a salt wedge which induces the formation of two turbidity maxima created by two different processes pauc h 1997 fluvio marine interface in a microtidal mediterranean estuarine environment the nepheloid layer supply problem journ rech oceanogr 22 3 83 90 the first process is a loss of charge due to the annulment of the current momentum driving sedimentation of the silt size material the second process is flocculation which results in deposition of fine sediment the end results of the combination of these two processes is a sedimentary sequence with two distinct sediment units silt below and clay minerals above granulometrical and mineralogical analysis of the sediment body enables the zone of sedimentation of each type of material to be determined and hence the style of sedimentation to be inferred illite quartz and dolomite are of detrital origin and accumulate close to the river mouths while smectite is deposited by both dynamical and flocculation processes and accumulating over the surface of the prodelta and also seaward by some 30 40 m depth calcite is of biogenic origin and is found further offshore associated with muddy sediments only

rayleigh wave signature in ionograms induced by strong earthquakes 1 after the magnitude 9 0 earthquake off the pacific coast of tohoku near the east coast of honshu japan which occurred on 11 march 2011 an unusual multiple cusp signature mcs was observed in ionograms at three ionosonde stations across japan to investigate the general characteristics of mcss we examined ionograms obtained during the period 1957 to 2011 from five ionosonde stations in japan after earthquakes with a seismic magnitude of 8 0 or greater a total of 43 such earthquakes occurred after 1957 as recorded in the database of the united states geological survey mcss were observed in 8 of 43 earthquakes allowing us to investigate the specific conditions of mcs appearance the appearance of mcss at different epicentral distances exhibits traveling characteristics at a velocity of 4 0 km s which is in the range of rayleigh waves there is a 7 min offset in delay time after the earthquake at each epicentral distance in the travel time diagram this offset is consistent with the propagation time of acoustic waves from the ground to the ionosphere launched by rayleigh waves mcss in ionograms provide a snapshot of vertical disturbances induced by a wave because the sweep time for the whole ionospheric echo traces is much shorter than the propagation time of acoustic waves the vertical scale of the disturbances is 10 30 km which corresponds to an acoustic wave period of 20 50 s at ionospheric heights

sediment budget of the rhone delta shoreface since the middle of the 19th century this study analyses long term 1841 1872 1895 1974 changes in the grand rhone prodeltaic lobe to 1 quantify the accumulation 2 determine the evolution of relict prodeltaic lobes and 3 establish long term relationships between river sediment discharge the shoreface and the continental shelf our results show a reduction of the sedimentation of the prodeltaic lobe at the main river mouth since 150 yr by a factor of 3 7 12 63 to 3 41 10 6 m 3 yr 1 at the minor mouth of the river erosion dominates and speeds up during the same period 0 53 to 1 34 10 6 m 3 yr 1 these changes are found to directly result from the river sediment input decrease related to the natural decreasing of the frequency of major floods end of the little ice age the reforestation in the catchment area the dam construction and the dredging activities since the 1950s our results indicate that while there is large sediment accumulation in the area around a growing prodeltaic lobe there is also a reduced contribution of the river sediments to the non adjacent beaches of the mouth following a shift in the river channel and mouth the relict prodeltaic lobes petit rhone st ferreol bras de fer and pegoulier are reworked by waves and their sediments contribute partially to the growth of the spits espiguette beauduc and gracieuse this suggests that there is a time shift between the input of river sediment to the sea and the build up of a beach the chronic erosion of the coastline is likely to continue in the future since 1 a river shift is not possible because the river channels are controlled by dykes and human intervention 2 the decrease of river sediment input and 3 the relict prodeltaic lobes constitute sedimentary reservoirs that are gradually being used up 2006 published by elsevier b v

detection and modeling of rayleigh wave induced patterns in the ionosphere 1 global positioning system gps allows the detection of ionospheric disturbances associated with the vertical displacements of most of the major shallow seismic events we describe a method to model the time and space distributions of rayleigh wave induced total electron content tec patterns detected by a dense gps array we highlight the conditions for which a part of the ionospheric pattern can be directly measured at teleseismic distance and above the epicenter in particular a satellite elevation angle lower than 40 is a favorable condition to detect rayleigh wave induced ionospheric waves the coupling between the solid earth and its atmosphere is modeled by computing the normal modes of the solid earth atmosphere system we show the dependency of the coupling efficiency on various atmospheric conditions by summation of the normal modes we model the atmospheric perturbation triggered by a given earthquake this shows that a part of the observation is a rayleigh induced radiation pattern and therefore characteristic of the seismic rupture through atmosphere ionosphere coupling we model the ionospheric perturbation after the description of the local geomagnetic field anisotropic effects we show how the observation geometry is strongly affecting the radiation pattern this study deals with the related data for two earthquakes with far field and near field observations using the japanese gps network geonet after the 12 may 2008 wenchuan earthquake china and after the 25 september 2003 tokachi oki earthquake japan respectively waveforms and patterns are compared with the observed tec perturbations providing a new step toward the use of ionospheric data in seismological applications

evolution of the rhone delta plain in the holocene abstract the delta plain of the rhone shows many sandy beach ridges cropping out at the surface we propose here a radiocarbon chronology for the accumulation of the sedimentary bodies and an interpretation of the morphology of the mouth lobes that they form morphologies of the lobes depend on four principal factors 1 the variation of the relative sea level which constitutes the morphogenic base level 2 the fluvial input volume of water discharge and sedimentary input number and position of the mouths 3 marine dynamics volume and direction of the longshore drift dominant wave direction 4 the accommodation space created by the rise of relative sea level along with the paleobathymetry onto which the lobe will prograde immediately in front of the delta and at sea our conclusions are the main holocene paleo delta lobes of ulmet and saint ferreol were contemporaneous being deposited from 4000 to 2000 yr bp however the fluvial style of their downstream channel meandering for ulmet channel and linear for saint ferreol and the lobe morphologies of both channels are contrasted rounded in the case of ulmet and elongated for saint ferreol the role of the accommodation space is confirmed by two recent drillholes traversing the entire holocene succession which reveal a prior stage of sedimentary filling in the case of the saint ferreol lobe thus limiting the accommodation space and favouring a rapid and pointed progradation of this lobe the decoupling between hydrological activity and progradation of lobe indicates the complexity of mechanisms in the large catchment basin of rhone however the high rate of progradation of saint ferreol lobe after 2900 bp is probably a consequence of the increase of human activity after this date the variation of relative sea level remains an important factor controlling the evolution of the rhone delta after 6000 bp the local stabilization of the relative sea level between 4585 bp and 3520 bp played an important role in the triggering of coastal progradation saint ferreol lobe eastern margin rhone delta

changes of the geomagnetic field vector obtained from lava sequences on the island of vulcano aeolian islands sicily abstract a combined geochronologic k ar and palaeomagnetic study has been conducted on five volcanic sections 70 flows on the island of vulcano the sections span the interval from 15 2 to 135 4 ka with large hiatuses rock magnetic investigations indicate that the natural remanent magnetisation nrm is carried by titanomagnetites in the four oldest sections with a contribution from high coercivity magnetic minerals in the youngest section palaeomagnetic directions obtained by thermal demagnetisation document a large magnetic excursion at around 110 ka with virtual geomagnetic poles vgps that lie over eastern siberia these directions may represent a volcanic record of the termination of the blake event only about 15 of the samples from 19 flows proved suitable for palaeointensity thellier and thellier determinations these measurements indicate that the geomagnetic field has varied at vulcano between 16 and 53 t in the explored time interval when combined with previous results obtained at mt etna for the period from 140 to 60 ka tric et al 1994 phys earth planet inter 85 113 129 these results document a broad low at around 115 ka the palaeointensity values from vulcano and etna are consistent with global values suggesting the presence of a dominant dipole field contribution these values on the other hand are significantly smaller than those recently obtained from la reunion in the southern hemisphere this suggests that large long lived non dipolar components of the geomagnetic field may be present at la reunion in the interval from 130 to 90 ka these observations are consistent with the fact that the vgp angular dispersion calculated from non excursional data is significantly smaller at vulcano than at la reunion

gps detection of ionospheric perturbations following the january 17 1994 northridge earthquake sources such as atmospheric or buried explosions and shallow earthquakes producing strong vertical ground displacements are known to produce pressure waves that propagate at infrasonic speeds in the atmosphere at ionospheric altitudes low frequency acoustic waves are coupled to ionospheric gravity waves and induce variations in the ionospheric electron density using global positioning system gps data recorded by the permanent gps network operating in southern california we computed ionospheric electron content time series for several days preceding and following the january 17 1994 mw 6 7 northridge earthquake we observe an anomalous signal beginning several minutes after the earthquake with time delays that increase with distance from the epicenter the signal frequency and phase velocity are consistent with results from numerical models of atmospheric ionospheric acoustic gravity waves excited by seismic sources as well as previous electromagnetic sounding results we believe that these perturbations are caused by the ionospheric response to the strong ground displacement associated with the northridge earthquake

two mode long distance propagation of coseismic ionosphere disturbances 1 using gps total electron content tec measurements we analyzed ionosphere response to the great kurile earthquake of 4 october 1994 high spatial resolution of the japanese dense array of gps receivers geonet provided us the unique opportunity to observe the evolution of coseismic ionospheric disturbances cid which propagated for more than 1800 km away from the epicenter plotting a traveltime diagram for the cid and using an array processing technique within the approximation of a spherical cid wavefront we observed a phenomenon of cid separation into two modes and we found that characteristics of the cid depend on the distance from the epicenter the maximum of the cid amplitude was observed at 500 km from the epicenter within the first 600 700 km the cid propagation velocity was about 1 km s which is equal to the sound speed at the height of the ionospheric f layer starting from 600 to 700 km out from the epicenter the disturbance seems to divide into two separate perturbations with each propagating at a different velocity about 3 km s for the one and about 600 m s for the other apparently the tec response in the far field of the cid source is a mixture of signals that further splits into two modes because of the difference in their velocities our observations are in good agreement with the results of space time data processing in the approximation of a spherical wavefront of cid propagation

gps velocity and strain fields in sicily and southern calabria italy updated geodetic constraints on tectonic block interaction in the central mediterranean 1 we present an improved rendition of the geodetic velocity and strain fields in sicily and southern calabria obtained through the analysis of 18 years of gps observations from continuous and survey station networks the dense spatial coverage of geodetic data provides precise quantitative estimates of previously established first order active kinematic features including i a narrow east west elongated belt of contraction 1 1 5 mm yr extending offshore northern sicily from ustica to stromboli across the aeolian islands ii a narrow east west trending contractional belt located along the northern rim of the hyblean plateau in southern sicily with shortening at up to 4 4 mm yr iii right motion 3 6 mm yr on the aeolian tindari letojanni fault atlf system a main shear zone extending from the aeolian islands to the ionian coast of sicily with significant transpression and transtension partitioned between discrete sectors of the fault iv transtension 1 mm yr across the sicily channel between sicily and north africa we use geodetic observations coupled to geological constraints to better elucidate the interplay of crustal blocks revealed in the investigated area in particular we focus on the atlf which forms the primary boundary between the sicilian and calabrian blocks the atlf juxtaposes north south contraction between sicily and the tyrrhenian block with northwest southeast extension in northeastern sicily and calabria contraction between sicily and tyrrhenian blocks probably arises from the main europe nubia convergence although sicily has a component of lateral motion away from nubia we found that convergence is not restricted to the northern offshore as commonly believed but is widely accommodated between the frontal belt and the northern rim of the hyblean foreland in southern sicily geodetic data also indicate that active right shear on the atlf occurs to the southeast of the mapped fault array in northern sicily suggesting the fault cuts through till the ionian coast of the island the small geodetic divergence between the hyblean and apulian blocks rimming on both sides the calabria block and subjacent ionian slab coupled with marine geophysical evidences in the ionian sea lends credit to the proposed deep root of the atlf and to a fragmentation of the ionian domain

magmatic control along a strike slip volcanic arc the central aeolian arc italy the regional stress field in volcanic areas may be overprinted by that produced by magmatic activity promoting volcanism and faulting in particular in strike slip settings the definition of the relationships between the regional stress field and magmatic activity remains elusive to better understand these relationships we collected stratigraphic volcanic and structural field data along the strike slip central aeolian arc italy here the islands of lipari and vulcano separate the extensional portion of the arc to the east from the contractional one to the west we collected 500 measurements of faults extension fractures and dikes at 40 sites most structures are nne ssw to nnw sse oriented eastward dipping and show almost pure dip slip motion consistent with an e w extension direction with minor dextral and sinistral shear our data highlight six eruptive periods during the last 55 ka which allow considering both islands as a single magmatic system in which tectonic and magmatic activities steadily migrated eastward and currently focus on a 10 km long 2 km wide active segment faulting appears to mostly occur in temporal and spatial relation with magmatic events supporting that most of the observable deformation derives from transient magmatic activity shorter term days to months rather than from steady longer term regional tectonics 102 104 years more in general the central aeolian case shows how magmatic activity may affect the structure and evolution of volcanic arcs overprinting any strike slip motion with magma induced extension at the surface

the formation of sedimentary strata in an allochthonous shelf environment the washington continental shelf nittrouer c a and sternberg r w 1981 the formation of sedimentary strata in an allochthonous shelf environment the washington continental shelf mar geol 42 201 232 models of fine scale 120 m shelf regions the inner shelf sand and mid shelf sandy silt are the predominant accretionary deposits on the shelf important sedimento logical observations obtained by boxcoring the upper 1 2 m of these deposits are a progressive decrease in grain size with distance from the columbia b downward coarsening within the seabed c loss of distinct sedimentary structure homogenization of sediment with distance from the columbia non dimensional parameters based on sediment transport and benthic biological studies can be used to relate rates of sediment mixing re working to rates of accumulation these parameters have the potential for quantitative prediction of strata formation from measurements of active processes physical and biological mixing can be assumed to remain relatively constant in an alongshelf direction on the washington shelf and accumulation rate is known from pb 210 geochronology to decrease away from the columbia together these factors tend to increase the ratio of mixing to accumulation with distance from the columbia and predict the sedimentological observations listed above

fate of metals in coastal sediments of a mediterranean flood dominated system an approach based on total and labile fractions the dynamics of sediment bound metals cs cu ni pb ti and zn were studied off the tet river western gulf of lion a typical mediterranean coastal river punctuated by short and violent flash floods spatial and temporal sampling strategies were combined to elucidate the fate of these elements in response to both the riverine sediment input and the offshore transport of these sediments through hydrodynamics our results show the temporal entrapment of riverborne particles and associated metals consecutively to a major flood event in the nearshore sedimentary unit called prodelta here deposition and resuspension mechanisms define a sedimentological cycle that could be followed completely in this study in terms of speciation between reactive labile and residual fractions along the fluvio deltaic continuum our results show that cu pb and zn are the most labile potentially mobile metals in the river in accordance with their contributions from anthropogenic sources but in the marine surficial sediments two main behaviours can be discriminated when compared to the riverine suspended particulate matter while pb and zn depict rather a constant labile fraction cu is characterized by decreasing levels up to 50 difference in terms of environmental impact these contrasting trends have direct repercussions for the contaminant dispersal in the coastal area whereas pb and zn conserve their enhanced levels because of their stronger affinity with fine sediments cu is marked by the entire loss of its anthropogenic component that is progressively transferred to the dissolved phase likely mediated by organic ligands we ascribe these behaviours to different post depositional partition mechanisms with respect to oxidation of the particulate organic phase at the bottom sediment water interface also analysis of one sediment core from the prodelta indicates that these early diagenetic processes govern the chemical forms of land derived contaminants sequestrated in the nearshore sedimentary archives c 2011 elsevier ltd all rights reserved

seismic observations of meteors coupling theory and observations to date coupling of acoustic waves directly with the earth s surface represents the bulk of the observed meteor related seismic signals while precursory and impact related seismic waves remain an observational rarity with proliferation of infrasound and seismic monitoring systems new opportunities exist to explore the relationship between earth s atmosphere andsurface continued studyofmeteorseismologywillleadto new methods to constrain energies sizes and fluxes for moderately cm to m sized meteoroids on earth and potentially on mars

nostradamus the radar that wanted to be a seismometer 1 surface waves emitted after large earthquakes are known to induce by dynamic coupling atmospheric infrasonic waves propagating upward through the neutral and ionized atmosphere those waves have been detected in the past at ionospheric heights using a variety of techniques such as hf doppler sounding or gps receivers the hf doppler technique particularly sensitive to the ionospheric signature of rayleigh waves is used here to show ionospheric perturbations consistent with the propagation of rayleigh wave phases r1 and r2 following the sumatra earthquake on the 28 march 2005 m 8 6 this is in our knowledge the first time that the phase r2 is detected by ionospheric sounding in addition we prove here that the ionospheric signature of r2 is also observed by over the horizon oth radar the latter was never used before to detect seismic signature in the ionosphere adding the oth radar to the list of the ionospheric seismometers we discuss and compare the performances of the three different instruments mentioned above namely hf doppler sounding gps receivers and oth radar

3 d process modelling of ancient storm dominated deposits by an event based approach application to pleistocene to modern gulf of lions deposits abstract a new numerical model was developed for 3 d characterization of deposits generated by storms along clastic coasts away from major rivers it is based on the assumption that the preserved sedimentary heterogeneities result mainly from a succession of deposits generated during both fair weather periods and major events storms in our case hydro sedimentary processes are first modelled during these major storms i transport parallel and transverse to the coast of suspended sediment by the strongest unidirectional currents littoral drift and downwelling currents ii sea bed erosion due to shear stress generated by unidirectional and wave induced oscillatory currents iii deposition of sediment fair weather deposits are modelled by an average deposition process the results of the numerical model i e the description of the sedimentary deposits are multi lithologic in three dimensions and with a flexible vertical resolution the latter is one of the main strengths of the model because the vertical description of the deposits can be adapted to the duration and extent of the simulation in order to save computation time very precise results definition of less than 1 mm can be obtained at a small time scale for storms lasting several hours to several days and reservoir scale results at a longer time scale the numerical model was applied to the gulf of lions which is located off the southern french coast in the north western mediterranean first present day storm deposits are simulated in order to validate the storm process modelling then sedimentary deposits formed over several thousands of years during the pleistocene are simulated in order to validate the sediment deposit modelling the model results fit well with observations and validate the approach of simulating the shelf deposits and their associated sedimentary heterogeneities at reservoir scale with an event and process based method this innovative approach seems promising for providing future geological models with realistic petrophysical properties

early muddy deposits along the gulf of lions shoreline a key for a better understanding of land to sea transfer of sediments and associated pollutant fluxes large quantities of sediment introduced by rivers especially during flood events lead to the formation of prodeltaic structures characterized by fine grained deposits in the proximal area of the shelf according to their mean grain size it is largely admitted in the literature that these deposits mainly stand below the storm wave base in the gulf of lions nw mediterranean however our data show that these muddy sediments also exist above the storm wave limit in the uppermost unit of the holocene prism the purpose of this work is therefore to draw a detailed sedimentological and geochemical portrait of these units and to discuss the processes involved in the sedimentation and remobilization of these sediments our results show that the fine particles accumulate earlier in the inner shelf in front of the nearby rivers in association with the chemical elements which are commonly associated with this grain size fraction e g organic carbon radionuclides and heavy metals this accumulation probably mainly occurs during storm and flood events the early deposits are then exposed to resuspension events and can actively participate to the distribution of fine grained sediment in the entire margin by advective transfers via the benthic nepheloid layer these fine grained nearshore prodeltas are a common feature of the mediterranean deltaic systems and mark the frontal processes that occur at the continent sea interface of non tidal seas our results especially point out the potential use of heavy metals as markers of the tracking of riverine sediments which is naturally an important condition when evaluating the ultimate fate of land derived pollutants in the marine realm but also more fundamental studies on the understanding of sedimentological processes and reconstruction of margin stratigraphies should consider these deposits as functional units for the distribution of platform sediments

river sediment discharge to the oceans present day controls and global budgets empirical relationships between river sediment yields and a large number of hydroclimatic biological and geomorphological parameters are investigated at the global scale for a set of 60 major world river basins the environmental characteristics were extracted from various global computer data sets and natural river sediment fluxes were taken from the literature it is found that sediment yields can be best correlated by forming the products of hydroclimatic and geomorphological factors that is runoff intensity basin slope an index characterizing rock hardness and an index characterizing rainfall variability over the year the best parameter combination varies to some extent when the rivers are grouped according to their average climatic situation but it is always a combination of the above mentioned parameters that yields the most significant models in arid climates however regression coefficients are greater than in humid climates indicating that erodibility is much greater than in arid climates when extrapolated to the total continental area on the basis of the corresponding data sets the empirical models result in a total sediment flux of about 16 gigatons discharged to the oceans every year which is in good agreement with previous estimates derived from compilations of world wide river data consequently two global maps are proposed showing the spatial distributions of river sediment yields on the continents as well as the inputs of these sediments to the oceans in a grid point scale by far most of the sediments originate from the young orogenic belts of the continents mainly due to a combination of steep morphologies and high runoff intensities

bichromatic excitation of long period rayleigh and air waves by the mount pinatubo and el chichon volcanic eruptions we have detected a new powerful source of low frequency seismic energy which is associated with some violent volcanic eruptions for the two eruptions for which we have identified this new source the spectrum is bichromatic consisting of two narrow phase coherent spectral lines these bands were centered on 3 76 and 5 14 mhz for the april 4 1982 el chichon eruption and on 3 68 and 4 44 mhz for the june 15 1991 mt pinatubo eruption during the latter 8 hour long eruption the resonance frequencies varied by less than 20 hz the strength of the source is sufficient to excite globe circling surface waves we conclude from these observations that volcanoes can excite harmonic tremors at much longer periods than previously observed our preferred source model involves feedback between local atmospheric oscillations and the eruption process the physics responsible for this feedback remains subject to speculations

infrasonic sounds excited by seismic waves of the 2011 tohoku oki earthquake as visualized in ionograms after the m 9 0 tohoku oki earthquake in 2011 strong deformation of ionogram echo traces forming multiple cusp signatures mcss were observed at three stations 790 1880 km from the epicenter the vertical structure of the ionospheric disturbances was determined by true height analysis and compared with broadband seismograph records at stations close to the ionosondes these ionospheric disturbances were caused by vertically propagating acoustic waves excited by the up down ground motion of seismic waves numerical simulations have shown that acoustic waves with a period of 15 40 s and amplitude of order 1 mm s at the ground level were sufficient to create mcss as sharp as those observed these acoustic wave parameters are consistent with the seismic records if the motion of the air mass on the ground level is assumed to be the same as the ground motion the travel time diagram of the seismic records along the line connecting the epicenter and ionosondes showed that the first mcs ionogram detected at each station was caused by p waves while the others were caused by rayleigh waves

last millennia sedimentary record on a micro tidal low accumulation prodelta tet nw mediterranean statistical sequential analysis was performed on a series of sediment cores collected from the tet prodelta in the gulf of lions northwestern mediterranean sea between october 2003 and october 2004 seabed changes during that period were correlated to hydrodynamic conditions waves and currents and river discharge low sediment supply prevents full preservation of new sediment strata on this low accumulation prodelta located on a microtidal storm dominated inner shelf severe meteorological events caused a rapid succession of erosion and deposition phases for example the december 2003 flood and storm produced a flood layer deposit that persisted for 2 months with only slight transformations due to early diagenesis and or bioturbation until a new storm event eroded this layer a typical sedimentary sequence was observed for the secular deposits composed of a 10 cm thick sandy layer overlaying siltyclayey layers these characteristic features were used to analyse the last millennia sedimentary record of the tet prodelta the low preservation of freshly deposited sediments and variable sedimentation rates during the last millennia period yield a sedimentary sequence formed by the outcropping of muddy prodeltaic units intersected by heterogeneous siltysandy units similar to those formed under present day hydrodynamic conditions no flood layer was found related to catastrophic flooding of the last century in the sedimentary record the little ice age 1550 1850 ad probably favoured the formation of a well developed muddy prodelta in the mouth of the tet river later on the decrease of sediment supply by rivers due to climate change and or human activities damming irrigation and the increase of the number of high energy storms reaching the coast induced a coarsening of the top sediment layer on this prodelta this modern change of the substrate is also observed in the composition of benthic biota found in the substrate

numerical simulation of the atmospheric signature of artificial and natural seismic events the mechanical coupling between solid planets and their atmospheres enables seismically induced acoustic waves to propagate in the atmosphere we numerically simulate this coupled system for two application cases active seismic experiments ases and passive seismic experiments a recent ase krishnamoorthy et al 2018 https doi org 10 1002 2018gl077481 observed the infrasonic signals produced by a seismic hammer to measure the sensitivity of observations to seismic parameters we attempt to reproduce the results from this experiment at short range by considering a realistic unconsolidated subsurface and an idealized rock solid subsurface at long range we investigate the influence of the source by using two focal mechanisms we found surface waves generate an infrasonic plane head wave in the ase case of the rock solid material for the passive seismic experiments the amplitude of atmospheric infrasound generated by seismic surface waves is investigated in detail despite some limitations the simulations suggest that balloon measurement of seismically induced infrasound might help to constrain ground properties

sediment entrainment on a wave graded shelf roussillon france abstract the sands of the inner shelf off the roussillon coast of the microtidal golfe du lion display a seaward fining texture and merge in water deeper than 20 30 m with midshelf muds there is a qualitative correspondence between the textural gradient and the seaward attenuating annual surface gravity wave power expended by tangential stress on the shelf surface various equations used to quantify the relation of sediment texture to fluid energy predict the trend of the observed textural gradient but overestimate its value an empirical threshold equation komar and miller 1975a b and a theoretical null point equation johnson and eagleson 1966 give comparable results implying that both may be describing the same state there is a disparity between the predictions of an incipient motion equation johnson and eagleson 1966 and the threshold equation probably because static instability of grains occurs prior to dynamic instability of grains in an increasing fluid velocity field theory forecasts that in water shallower than 30 m the sands are frequently entrained by shoaling waves particularly during the winter months the threshold of movement of sands in 5 m of water is exceeded for more than 40 of the year hence the grain size of the shallow water sands does not reflect the maximum energy level of the environment

seismoacoustic coupling induced by the breakup of the 15 february 2013 chelyabinsk meteor on 15 february 2013 around 03 20 00 utc the largest meteor reported since the 1908 tunguska event was observed as a fireball traveling through the earth s atmosphere exploding in an air burst near the city of chelyabinsk russia the rarity of such an event provides a unique window on the physics of meteoroid collision we report the fine seismic detection of rayleigh waves produced by the coupling of ground motion with the incident shock wave at distances up to 4000 km from the event combining information from seismic beam forming analysis recon structed trajectory from casual video records and remote sensing we identify the rayleigh waves as being initiated by the shock wave produced by the main blast that occasioned damages and injuries in chelyabinsk from the rayleigh wave observations we report a magnitude ms 3 7 seismic source

spatial variations of seismogenic stress orientations in sicily south italy abstract seismogenic stress orientations are estimated in the lithosphere of sicily by inversion of 131 local earthquake focal mechanisms fms selected from the literature an average misfit f 14 5 between stress tensor and fms indicates that the entire set of earthquakes is generated by a highly heterogeneous stress field detailed analysis of stress tensors and related earthquake misfits obtained for tens of subsets based on spatial separation of data allowed us to identify two main stress domains in the study region i a compressional domain including etna western sicily and the southern tyrrhenian sea offshore sicily where the 1 orientation roughly changes from nw se in the etna area and western sicily to nne ssw at the northeastern edge of the domain eolian islands and ii an extensional domain in northeastern sicily between the eolian islands and etna where 3 is oriented analogously to previously estimated in the easterly confining extensional area of the messina straits general agreement is found between this stress pattern and the gps crustal displacement vectors reported in the most recent literature for the study region moreover stress inversion enables us to locate the extensional domain more accurately than the presently available gps data finally the stress orientations estimated in the southern and western sectors of the study area etna and western sicily on and offshore match well with the displacement fields predicted for sicily by large scale models of plate motion conversely a mismatch is observed in the northeastern sector eolian islands and northeastern sicily we suggest that the joint action of africa eurasia convergence and ionian subduction trench retreat rollback of the subducting slab may explain the stress pattern detected in sicily in the present study work for computation of a finite element regional geodynamic model based on geophysical and geological data collected over the last few years has recently started with the purpose of quantitatively checking this hypothesis

multi dimensional distribution of near field ionospheric disturbances produced by the 2015 mw7 8 nepal earthquake abstract ionospheric anomalies possibly associated with large earthquakes particularly coseismic ionospheric disturbances have been detected by global positioning system gps a large nepal earthquake with magnitude mw7 8 occurred on april 25 2015 in this paper we investigate the multi dimensional distribution of near field coseismic ionospheric disturbances cids using total electron content tec and computerized ionospheric tomography cit from regional gps observational data the results show significant ionospheric tec disturbances and interesting multi dimensional structures around the main shock regarding the tec changes coseismic ionospheric disturbances occur approximately 10 20 min after the earthquake northeast and northwest of epicentre the maximum ridge to trough amplitude of cids is up to approximately 0 90 tecu min propagation velocities of the tec disturbances are 1 27 0 06 km s and 1 91 0 38 km s it is believed that the ionospheric disturbances are triggered by acoustic and rayleigh waves tomographic results show that the three dimensional distribution of ionospheric disturbances obviously increases at an altitude of 300 km above the surrounding epicentre predominantly in the entire region between 200 km and 400 km significant ionospheric disturbances appear at 06 30 ut from tomographic images this study reveals characteristics of an ionospheric anomaly caused by the nepal earthquake

the 2007 8 volcanic eruption on jebel at tair island red sea observed by satellite radar and optical images we use high resolution optical images and interferometric synthetic aperture radar insar data to study the september 2007 january 2008 jebel at tair eruption comparison of pre and post eruption optical images reveals several fresh ground fissures a new scoria cone near the summit and that 5 9 0 1 km2 of new lava covered about half of the island decorrelation in the insar images indicates that lava flowed both to the western and to the northeastern part of the island after the start of the eruption while later lavas were mainly deposited near the summit and onto the north flank of the volcano from the insar data we also estimate that the average thickness of the lava flows is 3 8 m resulting in a bulk volume of around 2 2 107 m3 we observe no volcano wide pre or post eruption uplift which suggests that the magma source may be deep the co eruption interferograms on the other hand reveal local and rather complex deformation we use these observations to constrain a tensile dislocation model that represents the dike intrusion that fed the eruption the model results show that the orientation of the dike is perpendicular to the red sea rift implying that the local stresses within the volcanic edifice are decoupled from the regional stress field

extension induced by volcanic loading in regional strike slip zones volcanoes and strike slip pull apart structures are commonly found together we use theoretical predictions and analogue modeling to evaluate the effect of volcanic loading in strike slip zones and the converse effect of regional strike slip faults on volcano structure theoretical predictions indicate that regional stress is reoriented by volcano loading to cause extension analogue models indicate that volcanoes in strike slip zones develop extensional pull apart structures a graben typically forms normal to the minimum regional stress axis 3 at a cone cones emplaced onto preexisting faults increase that fault9s tensional component if the substratum is weak enough to permit volcano spreading thrusts form normal to the maximum stress axis 1 a feedback situation can arise i e loading related extension allows more magma influx more eruption and thus increased loading this process can create large volcano tectonic depressions volcano structures may also be used as indicators of regional strike slip movements

a crust and upper mantle model of eurasia and north africa for pn travel time calculation abstract we develop a regional seismic travel time rstt model and method for use in routine seismic analysis the model parameterization is a global tessellation of nodes with a velocity profile at each node interpolation of the velocity profiles generates a 3d crust and laterally variable upper mantle velocity the upper mantle velocity profile at each node is represented as a linear velocity gradient which enables travel time computation in approximately 1 millisecond this computational speed allows the model to be used in routine analyses in operational monitoring systems we refine the model using a tomographic formulation that adjusts the average crustal velocity mantle velocity at the moho and the mantle velocity gradient at each node while the rstt model is inherently global our first rstt tomographic effort covers eurasia and north africa where we have compiled a data set of approximately 600 000 pn arrivals ten percent of the data set is randomly selected and set aside for testing purposes travel time residual variance for the validation data is reduced by 32 based on a geographically distributed set of validation events with epicenter accuracy of 5 km or better epicenter error using 16 pn arrivals is reduced by 46 from 17 3 km ak135 model to 9 3 km rstt model after tomography the median uncertainty ellipse area is reduced by 68 from 3070 km 2 ak135 to 994 km 2 rstt and the number of ellipses with area less than 1000 km 2 which is the area allowed for onsite inspection under the comprehensive nuclear test ban treaty is increased from 0 ak135 to 51 rstt

tsunami wave height estimation from gps derived ionospheric data large underwater earthquakes mw 7 can transmit part of their energy to the surrounding ocean through large seafloor motions generating tsunamis that propagate over long distances the forcing effect of tsunami waves on the atmosphere generates internal gravity waves that when they reach the upper atmosphere produce ionospheric perturbations these perturbations are frequently observed in the total electron content tec measured by multifrequency global navigation satellite systems gnss such as gps glonass and in the future galileo this paper describes the first inversion of the variation in sea level derived from gps tec data we used a least squares inversion through a normal mode summation modeling this technique was applied to three tsunamis in far field associated to the 2012 haida gwaii 2006 kuril islands and 2011 tohoku events and for tohoku also in close field with the exception of the tohoku far field case for which the tsunami reconstruction by the tec inversion is less efficient due to the ionospheric noise background associated to geomagnetic storm which occurred on the earthquake day we show that the peak to peak amplitude of the sea level variation inverted by this method can be compared to the tsunami wave height measured by a dart buoy with an error of less than 20 this demonstrates that the inversion of tec data with a tsunami normal mode summation approach is able to estimate quite accurately the amplitude and waveform of the first tsunami arrival

near bottom suspended sediment variability caused by storms and near inertial internal waves on the ebro mid continental shelf nw mediterranean abstract near bottom currents and suspended sediment concentrations ssc recorded on the ebro continental shelf at 60 m depth during the transition between fair and stormy weather have revealed some of the major processes controlling the sediment re suspension and transport at mid shelf depths in this nw mediterranean area storm waves were the main contributor to the transport of sediment although they only resuspended surface sediments during extreme wave conditions h s 4 5 m and t s 11 s during the recording period the net suspended sediment flux along the shelf was one order of magnitude higher than the net suspended sediment flux across the shelf and the resultant transport was towards the sw and seaward fluctuations of the near bottom ssc during fair weather showed a periodicity around 17 h and were related to the occurrence of near inertial internal waves caused by wind pulses during storm events the energy propagation of these internal waves reached critical angles at the mid and outer shelf which could favor the development and maintenance of the bottom nepheloid layer on the ebro continental shelf as well as on other mediterranean continental shelves

structural control on late miocene to quaternary volcanism in the ne honshu arc japan 1 volcanological and structural field data are used to define the tectonic control on the n s volcanic arc of ne honshu japan since late miocene during late miocene pliocene bimodal products were mainly erupted from along arc and ne sw aligned and elongated calderas the deformation pattern mostly consisted of n s dextral faults and subordinate ne sw extensional structures produced by ne sw compression this pattern because of the indentation of the kuril sliver is similar to that of oblique convergence settings magma rose and extruded along ne sw areas of localized extension created by the dextral faults these extensional areas were uncoupled with regard to those e w trending inferred to have focused the rise of melts from the subducting slab in the mantle during quaternary a larger amount of andesite was mainly erupted from along arc and e w aligned and elongated stratovolcanoes the deformation pattern mostly consisted of n s thrust faults and subordinate e w extensional structures produced by e w compression resulting from orthogonal convergence due to the variation in the absolute motion of the pacific plate the e w extensional structures are the shallowest expression of e w trending hot mantle fingers suggesting mantle crust coupling for the rise of magma such a coupling ensures 1 higher extrusion and 2 mixing between a deeper mafic and a shallower felsic magma generating the andesites the significantly larger volumes ma 1 200 km 1 of length of the arc of magma erupted during quaternary show that pure convergence conditions do not necessarily hinder the rise and extrusion of magma

convergence vs retreat in southern tyrrhenian sea insights from kinematics 1 the tyrrhenian sea is an extensional basin opened by trench retreat and back arc extension during subduction of the calabrian slab in the last 10 12 my subduction is still active beneath the semost part of the tyrrhenian sea as testified by seismicity down to 500 km depth by analyzing seismicity and geodetic data together with recent tomographic images we define the present day situation an evident n s compressional regime prevails in the tyrrhenian region west of the aeolian archipelago while east of them a nnw sse extension is documented by focal mechanisms and gps data with a much smaller strain rate with respect to the past the transition between these two domains is accommodated by a n s discontinuity zone which runs from aeolian islands to mt etna with an extensional to strike slip deformation

infrastructure and mechanics of volcanic systems in iceland the divergent plate boundary in iceland consists of more than two dozen systems where most of the volcano tectonic activity takes place at the surface the volcanic systems are characterised by 5 20 km wide and 40 100 km long swarms of tension fractures 102 m long normal faults 103 m long and volcanic fissures the holocene fissure swarms are confined to less than 10 000 year old basaltic lava flows mostly pahoehoe occurring near the centre of the active rift zone in any particular swarm the number of tension fractures exceeds that of normal faults all tension fractures and normal faults are vertical at the surface indicating that the surface parts were generated by an absolute tension in addition to a fissure swarm many volcanic systems have a central volcano some of which have developed collapse calderas in the late tertiary and pleistocene lava pile of iceland extinct volcanic systems are represented by local sheet swarms and regional dyke swarms the sheet swarms are normally circular or slightly elliptical several kilometres in radius and are confined to the extinct central volcanoes many swarms are associated with large plutons exposed at 1 2 km depth beneath the initial top of the rift zone and presumably the uppermost parts of extinct crustal magma chambers and in short traverses up to 90 of the rock may consist of sheets the sheets have a very variable strike dip on average 45 65 mostly towards the centre of the associated volcano and have an average thickness of about 1 m the regional dykes occur outside central volcanoes in swarms that are commonly 50 km long and 5 10 km wide in several kilometre long traverses commonly 1 5 of the rock consist of dykes but occasionally as much as 15 28 most regional dykes are subparallel and subvertical the average dyke thickness in the pleistocene swarms is less than 2 m but 4 6 m in the tertiary swarms while active the volcanic systems in the rift zone are supplied with magma from reservoirs located at the depth of 8 12 km at the boundary between the crust and upper mantle the reservoirs are partially molten with totally molten top regions and of cross sectional areas similar to those of the volcanic systems that they feed some active volcanic systems especially those that develop central volcanoes high temperature areas and calderas have in addition to the deep seated magma reservoirs shallow crustal magma chambers located at 1 3 km depth which in turn are fed by the deeper magma reservoirs it is proposed that the regional dyke swarms are supplied with magma largely from the deep seated reservoirs whereas the local sheet swarms are mainly fed from the associated crustal magma chambers because the volume of a crustal chamber is less than that of its deeper source reservoir a single magma flow dyke intrusion from the reservoir may trigger tens of magma flows sheet intrusions from the chamber which is one explanation for the enormous number of sheets associated with many central volcanoes the sheets follow the stress trajectories of the local stress fields around the source chambers whereas the regional stress field associated with the divergent plate movements controls the emplacement of the regional dykes it is suggested that many dykes develop as self affine some as self similar structures when applied to the krafla volcanic system in northern iceland model calculations suggest that a magma flow from the krafla reservoir with regional dyke formation should occur on average once every several hundred years and that tens of sheets might be injected from the shallow krafla chamber and triggered by a single magma flow from the krafla reservoir these results are in broad agreement with the available data

modeling of atmospheric coupled rayleigh waves on planets with atmosphere from earth observation to mars and venus perspectives acoustic coupling between solid earth and atmosphere has been observed since the 1960s first from ground based seismic pressure and ionospheric sensors and since 20 years with various satellite measurements including with global positioning system gps satellites this coupling leads to the excitation of the rayleigh surface waves by local atmospheric sources such as large natural explosions from volcanoes meteor atmospheric air bursts or artificial explosions it contributes also in the continuous excitation of rayleigh waves and associated normal modes by atmospheric winds and pressure fluctuations the same coupling allows the observation of rayleigh waves in the thermosphere most of the time through ionospheric monitoring with doppler sounders or gps the authors review briefly in this paper observations made on earth and describe the general frame of the theory enabling the computation of rayleigh waves for models of telluric planets with atmosphere the authors then focus on mars and venus and give in both cases the atmospheric properties of the rayleigh normal modes and associated surface waves compared to earth the authors then conclude on the observation perspectives especially for rayleigh waves excited by atmospheric sources on mars and for remote ionospheric observations of rayleigh waves excited by quakes on venus

acoustic environment of the martian surface prompted by the mars microphone aboard the 1998 mars polar lander a theoretical study of the acoustical environment of the martian surface has been made to ascertain how the propagation of sound is attenuated under such conditions and to predict what sounds may be detectable by a microphone viscous and thermal relaxation termed classical absorption molecular relaxation and geometric attenuation are considered classical absorption is stronger under martian conditions resulting in sounds in the audible frequencies 20 hz to 20 khz being more strongly attenuated than in the terrestrial environment the higher frequencies 3000 hz will be severely attenuated as the absorption is frequency dependent at very low infrasound frequencies i e 10 hz attenuation will be mostly due to geometric spreading of the propagating wave front and will therefore be more similar to the terrestrial surface environment probable sound sources in the landed environment include wind blown dust and sand from large dust storms dust devils and possible associated electrostatic discharge the sounds most likely to be detected will be sounds generated by the lander itself and aeroacoustic noises generated by winds blowing against the lander and its instruments

a la icp ms study of minerals in the rocche rosse magmatic enclaves evidence of a mafic input triggering the latest silicic eruption of lipari island aeolian arc italy the volcanic products of lipari island aeolian arc italy younger than 10 ka are mostly aphyric rhyolitic pumices and obsidians emitted during unusual strombolian type eruptions which ended with the emplacement of lava flows the last volcanic activity on the island dates back to 1230 40 ad with the extrusion of rocche rosse rr obsidian lava flow recently mafic enclaves of latitic to trachytic composition have been identified and an evolution process between these enclaves and the rhyolitic magma has been documented in detail davi m 2007 the rocche rosse rhyolitic lava flow lipari aeolian islands magmatological and volcanological aspects plinius supplement to the european journal of mineralogy 33 1 8 in this work textural and trace element investigation of mineral phases of the rr enclaves such as crystals of clinopyroxene olivine plagioclase alkali feldspar and biotite was carried out to delineate the most recent feeding system of the island since such a reconstruction could be significant in terms of hazard forecasting the results indicate that most of the mineral phases are reversely or oscillatory zoned with respect to both major and trace elements suggesting an early crystallization under low f o 2 conditions from melts of intermediate composition followed by a later growth from a more mafic presumably shoshonitic basaltic magma than that from which their cores crystallized crystals of magnesium rich pyroxene and forsteritic rich olivine are indicative of the presence of this shoshonitic basaltic magma based on microanalytical data it is suggested here that the feeding system of recent lipari volcanic activity was characterized by a shoshonitic basaltic magma originating from a deep reservoir which may have evolved and stopped in the crust generating zoned magma chambers at different depths in which latitic and rhyolitic magmas reside the sudden arrival of a new input of mafic melt may have interacted with these resident fractionated magmas and triggered the eruption a plumbing system of this type has been shown to be active in the southern sector of the aeolian islands since the last 42 ka gioncada a mazzuoli r milton a 2005 magma mixing at lipari aeolian islands italy insights from textural and compositional features of phenocrysts j volcanol geotherm res 145 97 118 peccerillo a frezzotti m l de astis g ventura g 2006 modeling the magma plumbing system of vulcano aeolian islands italy by integrated fluid inclusion geobarometry petrology and geophysics geology 34 17 20 it is concluded that the hazard assessment of lipari island should take into account the arrival of deep and never erupted mafic melts as eruption triggers of more evolved shallower magma bodies

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

neogene and quaternary rollback evolution of the tyrrhenian sea the apennines and the sicilian maghrebides reconstruction of the evolution of the tyrrhenian sea shows that the major stage of rifting associated with the opening of this basin began at similar to10 ma it involved two episodes of back arc extension which were induced by the rollback of a west dipping subducting slab the first period of extension 10 6 ma was prominent in the northern tyrrhenian sea and in the western part of the southern tyrrhenian sea the second period of extension mainly affected the southern tyrrhenian sea began in the latest messinian 6 5 ma and has been accompanied by subduction rollback at rates of 60 100 km myr 1 slab reconstruction combined with paleomagnetic and paleogeographic constraints indicates that in the central apennines the latest messinian 6 5 ma arrival of a carbonate platform at the subduction zone impeded subduction and initiated a slab tear and major strike slip faults these processes resulted in the formation of a narrow subducting slab beneath the ionian sea that has undergone faster subduction rollback and induced extreme rates of back arc extension

ionospheric disturbances infrasound waves over the czech republic excited by the 2011 tohoku earthquake 1 a train of large amplitude infrasound wave packets was observed by multipoint continuous doppler sounding system in the ionosphere over the czech republic on 11 march 2011 it is shown that these infrasound wave packets originated from vertical motion of the ground surface that was caused by arrival of seismic waves generated by the strong tohoku earthquake the infrasound wave packets were observed in the ionosphere at heights of 210 220 km about 9 min after the detection of corresponding wave packets on the ground which is consistent with the calculated time for vertically propagating infrasound waves absolute values of cross correlation coefficients between ionospheric and ground measurements are typically higher than 0 9 for two wave packets 0 98 the individual wave packets recorded on the ground have different observed horizontal velocities and correspond to different types of seismic waves a comparison of vertical velocities of ground motion with oscillation velocities of air particles in the ionosphere indicates that almost 1 10 of the infrasound energy flux excited at the ground reached the altitudes of 210 220 km for wave periods longer than 30 s estimates of sound attenuation are performed it is also shown that it is necessary to consider the value of electron density gradient at the reflection height of the sounding radio wave and air plasma compression owing to the infrasound wave to get reasonable estimates of oscillation velocities of air particles from doppler shift frequencies

observation and modeling of the winter coastal oceanic circulation in the gulf of lion under wind conditions influenced by the continental orography fetch experiment 1 hydrological and currentmeter observations were collected on the continental shelf and slope of the gulf of lion during the fetch experiment 13 march to 15 april 1998 results from the first part of the cruise characterized by strong northern winds are presented the hydrological structures evidence well mixed water masses on the eastern and western ends of the shelf in the central part the situation is more complex with the influence of the rhone river s freshwater plume in the first 40 m of the water column and closer from the bottom with the confrontation of downwelled coastal cold water and upwelled warmer and saltier slope water current measurements show the path of the cyclonic circulation along the slope which is part of the general circulation of the western mediterranean and suggest the presence of large and temporary eddies on the shelf this oceanic circulation is simulated with a free surface three dimensional model using realistic forcing the model outputs are in agreement with the main hydrological and circulation patterns the results further indicate that coastal eddies are generated by the mesoscale structure of the wind field

dike emplacement at bardarbunga iceland induces unusual stress changes caldera deformation and earthquakes a 45 km long regional dike was emplaced over a period of 2 weeks in august 2014 at the boundary between the east and north volcanic zones in iceland this is the first regional dike emplacement in iceland monitored with modern geophysical networks the importance of which relates to regional dikes feeding most of the large fissure e g eldgja 934 and laki 1783 and lava shield e g early holocene skjaldbreidur and trolladyngja eruptions during this time the dike generated some 17 000 earthquakes more than produced in iceland as a whole over a normal year the dike initiated close to the bardarbunga volcano but gradually extended to the northeast until it crossed the boundary between the east volcanic zone evz and the north volcanic zone nvz we infer that the strike of the dike changes abruptly at a point from about n45 e coinciding with the trend of the evz to n15 e coinciding with the trend of the nvz this change in strike occurs at latitude 64 7 exactly the same latitude at which about 10 ma dikes in east iceland change strike in a similar way this suggests that the change in the regional stress field from the southern to the northern part of iceland has been maintained at this latitude for 10 million years analytical and numerical models indicate that the dike induced stress field results in stress concentration around faults and particularly shallow magma chambers and calderas in its vicinity such as tungnafellsjokull kverkfjoll and askja in particular the dike has induced high compressive shear and tensile stresses at the location of the bardarbunga shallow chamber and caldera ring fault where numerous earthquakes occurred during the dike emplacement many of which have exceeded m5 the largest m5 7 the first segment of the dike induced high tensile stresses in the nearby part of the bardarbunga magma chamber ring fault resulting in radially outward injection of a dike from the chamber at a high angle to the strike of the regional dike the location of maximum stress at bardarbunga fluctuates along the chamber ring fault boundary in harmony with dike size and or pressure changes and encourages ring dike formation and associated magma flow within the chamber caldera collapse and or eruption in some of these volcanoes is possible most likely in bardarbunga but depends largely on the future development of the regional dike

tectonics and seismicity of the tindari fault system southern italy crustal deformations at the transition between ongoing contractional and extensional domains located above the edge of a subducting slab 1 the tindari fault system southern tyrrhenian sea italy is a regional zone of brittle deformation located at the transition between ongoing contractional and extensional crustal compartments and lying above the western edge of a narrow subducting slab onshore structural data an offshore seismic reflection profile and earthquake data are analyzed to constrain the present geometry of the tindari fault system and its tectonic evolution since neogene including the present seismicity results show that this zone of deformation consists of a broad nnw trending system of faults including sets of right lateral left lateral and extensional faults as well as early strike slip faults reworked under late extension earthquakes and other neotectonic data provide evidence that the tindari fault system is still active in the central and northern sectors and mostly accommodates extensional or right lateral transtensional displacements on a diffuse array of faults from these data a multiphase tectonic history is inferred including an early phase as a right lateral strike slip fault and a late extensional reworking under the influence of the subduction related processes which have led to the formation of the tyrrhenian back arc basin within the present regional geodynamic context the tindari fault system is interpreted as an ongoing accommodation zone between the adjacent contractional and extensional crustal compartments these tectonic compartments relating to the complex processes of plate convergence occurring in the region the tindari fault system might also be included in an incipient oblique extensional transfer zone linking the ongoing contractional belts in the calabrian ionian and southern tyrrhenian compartments

crustal motion along the calabro peloritano arc as imaged by twelve years of measurements on a dense gps network abstract in this work we show the results of 12 years of continuous and survey mode gps measurements carried out along the western part of the calabro peloritano arc from 1996 until the more recent acquisitions in 2008 the results highlight that a nw se oriented 0 15 strain yr extension across the messina strait and the aeolian tindari letojanni fault system is active moreover a n s compressive strain rate 0 65 strain yr is acting across vulcano and lipari islands coupled with an extensional strain rate of 0 15 strain yr in the e w direction finally taking into account the observed horizontal velocity field an analytical inversion was performed to obtain a reliable model of deformation of the investigated area the main results are consistent both with focal mechanism solutions and the current structural setting of the investigated area

normal modes modelling of post seismic ionospheric oscillations since 1960 several experiments have shown strong perturbations of the ionosphere after earthquakes for the biggest quakes doppler ionospheric soundings have revealed displacements of several tens of meter of the ionized layers e and f an accurate modelling of these phenomena was however never described we present here synthetic displacements of such oscillations and compare it with experimental data realistic models of the atmosphere including viscosity are used as well as realistic earth and seismic source model these ionospheric oscillations are computed by normal modes summation taking explicitly into account the coupling between the solid earth and the open atmosphere they are associated to the rayleigh fundamental surface waves we obtain a good agreement between synthetics and observations so it should be possible to use this method to study the ionospheric post seismic perturbations and possibly the high altitude profile of the density and the viscosity of the atmosphere

oblique rifting in salina lipari and vulcano islands aeolian islands southern italy a structural analysis carried out on the volcanic products of the islands of salina lipari and vulcano aeolian archipelago points out that the large scale tectonic setting is dominated by nw se trending right lateral extensional strike slip faults and by n s to ne sw trending normal faults and fractures this fault pattern generates pull apart type structures developing between different right hand overlapping fault segments and a characteristic extensional imbricate fan geometry at the tip of the major strike slip faults all the structures representing the surface expression of an active crustal discontinuity which controls the evolutionary history of the magmatism of the three islands are kinematically compatible with a n100 e extension related to a rifting process affecting southern italy

post depositional alteration and preservation of sedimentary event layers on continental margins i the role of episodic sedimentation the degree of post depositional alteration and hence the preservation potential of sedimentary event beds and transient signals is determined by the outcome of a race between biological and to a lesser extent physical processes that conspire to destroy a signal and sediment accumulation which advects the layer or signal out of the surface mixing zone preservation potential specifically depends on the relative magnitudes of the 1 biological mixing intensity sometimes parameterized as a biodiffusivity db 2 mixing layer thickness 3 layer or signal thickness and 4 sediment accumulation rate these terms control the dissipation time i e time required to destroy a signal and the transit time i e time necessary to advect a signal through the surface mixing layer on fine grained upper continental margins in general and the eel river shelf northern california in particular biological mixing intensity is high i e db ranges from 10 to 100 cm2 yr mixing layer thickness is large 10 cm and sediment accumulation rates are rapid 0 1 1 cm yr despite the high sediment accumulation rates transit times through the surface mixing layer range from decades to a century signal dissipation times are considerably shorter 1 3 yr for beds up to 6 cm thick imaged in x radiographs and 2 15 yr for the grain size signature of beds up to 8 cm thick therefore event layers and their corresponding grain size signature have a low probability of preservation however short lived episodic sedimentation events e g oceanic floods can instantaneously advect material through the surface mixing layer thereby preserving event beds and transient signals on the eel river shelf the sequential timing of episodic sedimentation events has exerted a first order control on the resultant stratigraphic record presence absence of layers and grain size fluctuations episodic sedimentation a hallmark of continental shelf settings is key to understanding strata formation and preservation on margins

evidence of recent sedimentation in the eastern irish sea the recent sedimentation history of the eastern irish sea has been investigated by radiocarbon dating age versus depth profiles of the shells of the gastropod turritella communis risso indicate that sedimentation has been taking place at two sites at a relatively slow but constant rate 0 02 0 08 cm a 1 for the past 3000 4000 years at a third site sedimentation appears to have been more variable and more rapid 0 3 cm a 1 dating t communis shells provides a more reliable indicator of the sediment accumulation rate than dating the bulk sediment carbonate fraction the latter is predominantly of marine origin but has been reworked and unlike the shells is subject to the intense mixing by bioturbation which characterizes the muddy sediments of this area bulk sediment carbonate ages are much greater than those of t communis at equivalent depths 10 300 15 300 yrs and 130 3800 yrs respectively and the profiles are more variable leading to difficulties in interpretation