diapiric transfer of melt in kilauea iki lava lake hawaii a quick efficient process of igneous differentiation kilauea iki lava lake formed in 1959 is a large pond of picritic basalt average mgo content 15 34 by weight which has cooled and crystallized as a small self roofed magma chamber repeated drilling of the upper crust of the lake down to its molten core and more recent 1981 drilling through the thermal maximum and part way through the lower crust have made it possible to monitor the differentiation processes in the lake in detail differentiation processes recognized as active in the lake include rather inefficient settling of the larger 2 10 mm olivine phenocrysts formation of segregation veins and formation of diapir like vertical olivine rich bodies all processes which occur in one or more of the other kilauean lava lakes as well in addition most of the central part of kilauea iki has been affected by diapiric melt transfer in this process relatively low density liquid present at 1145 1160 c rose from within the loose crystal mush at the base of the lens of melt and intruded the equivalent thermal horizon at the top of the lens of melt passing through the hotter but denser melt in the core of the lake without mixing the source volume from which the low density liquid was extracted is depleted in tio 2 and other incompatible elements and enriched in feo and cao the upper part of the lake shows the opposite effects the crystalline assemblage present was olivine augite minor plagioclase the crystallinity of both the source and receiving layers was low enough that no obvious textural imprint was left by the transfer process the principal evidence for its occurrence is the chemical zonation of the lake seen in core from depths of 13 to 80 m diapiric melt transfer was active from 1960 to 1971 and has affected most of the central part of the lake from 13 m to at least 80 m the process ran simultaneously with the other three main differentia tion processes but started and stopped independently of the others calculations suggest that between 21 and 42 wt liquid has been extracted from the depleted zone at 56 78 m in the center of the lake making this a very efficient process of chemical differentiation

igneous layering through oscillatory nucleation and crystal settling in well mixed magmas oscillatory or competitive nucleation about a binary or perhaps pseudo binary eutectic and ensuing crystal growth and settling is a commonly suggested means of producing layering in magmatic systems a quantitative model is presented of this outwardly relatively simple process of crystal nucleation growth and settling in an otherwise initially crystal free magma avrami style kinetics of crystallization in an always wellmixed body buried in conductive wall rock are coupled to a stokes like formulation of crystal settling in magma whose viscosity depends on temperature and crystallinity two dimensionless numbers se the settling number and av the avrami or kinetic number govern all the results av and se measure the relative importance of crystallization time and settling time respectively relative to the overall cooling time for any value of av which increases strongly with the maximum nucleation and growth rates and cooling time layering is possible only over a range or window of values of se both above and below this window a single layer crystalline below vitric above forms and within this window the number of layers increases systematically with increasing av and se grain size within any single layer generally coarsens upward because the characteristic settling and cooling times both depend on body thickness the lower limit of the settling window is also dependent on sheet thickness within the confines of this model and for nucleation and growth rates set by those observed in natural systems layering is unlikely in sheet like magmas thinner than about 100 m when the body is not always well mixed and crystallization is within inward propagating solidification fronts it is expected that this minimum body thickness will increase

effects of winter convection on the deep layer of the southern adriatic sea in 2012 1 we analyze aspects concerning the thermohaline changes observed in the near bottom layer of the southern adriatic pit sap in the eastern mediterranean after the arrival of abundant and exceptionally dense water 30 kg m 3 produced in the shallow northern adriatic sea during winter 2012 for this purpose we use temperature t salinity s and current time series collected at the e2m3a deep ocean observatory of the southern adriatic and conductivity temperature depth data obtained both in the southern and middle adriatic from freely drifting profiling floats the dense water produced in the northern adriatic arrived in the central and deepest part of the sap as a series of individual pulses starting on 10 march 2012 while a stronger and prolonged signal that significantly modified the local deep water stratification arrived after 10 april 2012 as a consequence t and s suddenly decreased 0 15 c and 0 015 thus interrupting positive t and s bottom trends observed during the previous 5 years and producing a density increase of 0 02 kg m 3 such variability has been rarely observed in the area we ascribe its occurrence to the concomitance of exceptionally harsh and long lasting bora wind scarce precipitation and low river discharge over the northern adriatic during winter 2011 2012 eventually this newly formed addw reached the strait of otranto during july 2012 its characteristics profoundly differed from those observed in the previous decade hence a noticeable variability in structure and circulation of the abyssal layers of the ionian basin is likely to occur in the near future

sea surface circulation variability in the ionian adriatic seas abstract the surface circulation of the ionian and adriatic seas is explored by the re analysis of available datasets that estimate the mean monthly ocean state for the 60 years long time period 1955 2015 emphasis is given to the major recurrent and transitional events in the area two circulation indices are utilized for the quantification of the cyclonic or anticyclonic circulation modes and intensity one based on the vorticity flux of the reconstructed mean monthly surface velocity field and another based on an appropriately modified version of the velocity field such quantification consequently allows for a detailed analysis of the surface circulation variability for the entire ionian and adriatic basins as well as for sub regions of particular interest discontinuities associated with possible regime shifts of the examined flow field were identified by time series analysis of the circulation indices and compared to well documented events in the hydrography of the studied area subsequently the statistically significant components of the surface circulation variability were resolved out of a red noise background in the time frequency domain and their evolution was studied the results highlight the presence of various circulation modes and reversals in different temporal scales mainly seasonal and decadal to inter decadal which are discussed in reference to the dynamics of both the sub regional western northern eastern and southern ionian as well as northern and southern adriatic and of the basin wide ionian or adriatic spatial scales the relationships of the surface circulation variability between the ionian and the adriatic basins are also assessed through wavelet coherence

the skaergaard layered series part ii magmatic flow and dynamic layering re examination of textural and structural features of the skaergaard intrusion has clarified the process responsible for various forms of layering two general types are distinguished one produced by magmatic flow and another by non dynamic processes such as compaction and varied nucleation and growth of crystals our concern here is mainly with layering of the first type magmatic flow results in contrasting layers and strong foliation accompanied by a linear orientation of elongated minerals it is associated with slumping and cross bedding in a zone near the margins of the intrusion rocks in the interior of the layered series are foliated and commonly layered but have little or no lineation their layering cannot be due solely to deposition from currents the principal structural elements produced by dynamic processes in the magmatic state foliation lineation shear zones folds and current structures define parallel belts mainly around the western and northern margins their distribution suggests that the strongest component of flow was for the western side and that its strength decreased toward the east shear flow trajectories deduced from lineations and kinematic indicators confirm this asymmetry and point to mass movement toward the southeastern part of the floor

long lived mesoscale eddies in the eastern mediterranean sea analysis of 20 years of aviso geostrophic velocities we analyzed 20 years of aviso data set to detect and characterize long lived eddies which stay coherent more than 6 months in the eastern mediterranean sea in order to process the coarse gridded 1 8 aviso geostrophic velocity fields we optimized a geometrical eddy detection algorithm our main contribution was to implement a new procedure based on the computation of the local and normalized angular momentum lnam to identify the positions of the eddy centers and to follow their lagrangian tra jectories we verify on two mesoscale anticyclones sampled during the egypt campaign in 2006 that our methodology provides a correct estimation of the eddy centers and their characteristic radius corresponding to the maximal tangential velocity our analysis reveals the dominance of anticyclones among the long lived eddies this cyclone anticyclone asymmetry appears to be much more pronounced in eastern mediter ranean sea than in the global ocean then we focus our study on the formation areas of long lived eddies we confirm that the generations of the ierapetra and the pelops anticyclones are recurrent and correlated to the etesian wind forcing we also provide some evidence that the smaller cyclonic eddies formed at the southwest of crete may also be induced by the same wind forcing on the other hand the generation of long lived eddies along the libyo egyptian coast are not correlated to the local wind stress curl but surprisingly their initial formation points follow the herodotus trough bathymetry moreover we identify a new formation area not discussed before along the curved shelf off benghazi

surface geostrophic circulation of the mediterranean sea derived from drifter and satellite altimeter data abstractdrifter observations and satellite derived sea surface height data are used to quantitatively study the surface geostrophic circulation of the entire mediterranean sea for the period spanning 1992 2010 after removal of the wind driven components from the drifter velocities and low pass filtering in bins of 1 1 1 week maps of surface geostrophic circulation mean flow and kinetic energy levels are produced using the drifter and or satellite data the mean currents and kinetic energy levels derived from the drifter data appear stronger higher with respect to those obtained from satellite altimeter data the maps of mean circulation estimated from the drifter data and from a combination of drifter and altimeter data are however qualitatively similar in the western basin they show the main pathways of the surface waters flowing eastward from the strait of gibraltar to the sicily channel and the current transporting waters back westward along the italian french and spanish coasts intermi

decadal variations of circulation in the central mediterranean and its interactions with mesoscale gyres abstract the most prominent oceanographic features in the central mediterranean are decadal reversals of the northern ionian gyre nig interpreted in terms of internal processes altimetry data drifter data and model surface salinity products are used in this paper to define some specific features of the circulation related to the anticyclonic or cyclonic nig modes results not only highlight different shapes and intensities of the mid ionian jet and northern ionian meander among the two circulation mode but emphasize distinct behaviour within the same mode imputable to the variability of the mesoscale quasi permanent features the wind driven messina rise vortex on the western side of the northern ionian and the pelops gyre on the eastern side of the northern ionian show different behaviour during the first 1993 1996 and the second 2006 2010 anticyclonic periods related to the cyclonic activity along the dense water pathway when the dense water was of aegean origin 1993 1996 aegean anticyclone the cyclonic mesoscale activity on the eastern flank of the ionian overwhelmed the anticyclonic wind forcing and led to the disappearance of the pelops gyre when the dense water was of adriatic origin 2006 2010 adriatic anticyclone the strengthening of cyclonic mesoscale activity on the western flank of the ionian caused the shape change of the messina rise vortex favouring its longitudinal extension the zonally elongated messina rise vortex reduced the inflow of atlantic water in the northern ionian and induced a strengthening of the eastward flowing mid ionian jet in the southern ionian and cretan passage from these results it emerges that the interannual variability of the wind driven quasi permanent mesoscale gyres in the ionian is influenced by internal forcing location of the deep water formation site aegean or adriatic sea in turn related to the major local climatic shift occurred in the last decades the eastern mediterranean transient we show that the interplay between decadal and interannual variability or rather between basin wide and mesoscale circulation affected the intrinsic characteristics of the nig reversals

coseismic crustal deformation from microseismicity in the patras area western greece summary the patras area lies in the western part of central greece it is an area characterized by high seismicity and complex neotectonics several devastating earthquakes have occurred in the region since 600 bc contemporary crustal deformation is examined in this area using microearthquake data recorded over a lengthy period during 1983 84 by the patras seismic network principally and to a lesser extent by the volos seismic network the microseismicity 1 8 3 9 ml defines a zone deepening to the ne which justifies a possible extension of the gulf of corinth major graben towards the trikhonis lake to the nw spectra of 108 well located microearthquakes are estimated using p waves obtained by selective windowing designed to include only the p phase seismic moments in the range 0 3 45 7 1012 nm are obtained accompanied by estimates of seismotectonic source parameters including source radii average stress drop and average coseismic slip poor correlation is found between seismic moment and magnitude and the likely reason is the complex nature of the neotectonic regime existing in the area two zones differing in crustal deformation characteristics are observed the corinth trikhonis zone reveals two sets of characteristic faults the first set is represented by microearthquakes showing distinctive and relatively higher seismic moments in conjunction with lower stress drops and seismic slips this set of faults shows greater source radius than the second set and therefore the faults are longer the second set is characterized by an almost constant source radius within the range of uncertainty and a wide range of seismic moments stress drops and seismic slips the rio zone is characterized by low seismic slip stress drop and fault radii with the exception of the locality south of the city of patras where relatively higher seismic slip stress drop and fault radius are observed

eddy formation by overflows in stratified water abstract the formation of eddies by dense overflows in stratified water is examined by laboratory experiments the dense fluid initially flows down the slope but turns under the influence of rotation to flow along the slope the inviscid alongslope flow is continuously drained by a viscous ekman layer that flows more directly downslope in some cases this ekman layer flow becomes unstable to growing waves under certain conditions strong cyclonic vortices form in the ambient fluid above the alongslope flow due to vortex stretching causing the dense fluid to break up into a series of domes there are three main mechanisms for this first the initial downslope flow of the current before it turns under the influence of rotation may take captured upper layer fluid with it out into deeper water second adjustment of the current to geostrophic balance stretches the fluid column above the current and finally the continuous viscous draining from the current and later from the domes also causes stre

crystal mush compaction and the origin of pegmatitic segregation sheets in a thick flood basalt flow in the mesozoic hartford basin connecticut

the skaergaard layered series part iii non dynamic layering layering in the skaergaard intrusion has been divided into two introduction general types one produced by magmatic flow and another by recent studies of the structural and textural features of processes resulting from variations of rates of nucleation and crysthe skaergaard intrusion mcbirney nicolas 1997 tallization and in the case of the layered series by compactionhave distinguished two broad types of layering one related processes modal variations caused by shifts of cotectic produced by the dynamic effects of magmatic flow and proportions produce thick layers which in the layered and upper another by processes that operate in situ such as varied border series are diffuse and normally lack strong foliation and nucleation and growth of crystals recrystallization or by lineation in the marginal border series the layers are thinner and compaction related mechanisms we refer to layering sharper possibly because the rate of accumulation was slower formed by these latter processes as non dynamic to oscillatory nucleation may have played a role in producing fineemphasize that it is not the result of fluid dynamic scale cyclic layers but it was less important than solution and processes although most layering combines elements of reprecipitation during slow cooling and ostwald ripening evidence more than one process the contribution of each mechfor compaction is found in deformed plagioclase laths and a relative anism can usually be recognized from its distinctive form deficiency of incompatible elements in rocks formed on the floor and setting layering related to compaction becomes sharper with increasing the distinguishing features of dynamic magmatic layheight in the layered series until it suddenly disappears above the ering have been described in part ii of this series mcbirtrough horizon near the base of upper zone b mechanical sorting ney nicolas 1997 they are best seen near the steep during compaction may have produced crude layering but if it did margins of the layered series in what wager brown the evidence has long since been destroyed by the superimposed effects 1968 referred to as the cross bedded zone where the of solution and reprecipitation when interstitial liquid rose through layering is disrupted by slumping and channeling and the overlying crystals and re equilibrated with them numerical the rocks have a marked foliation and lineation simulations illustrate how small differences of surface energy caused layering not associated with magmatic flow takes a by variations of grain size textural dependence of solubility and variety of forms but we can distinguish two general pressure solution can cause segregation of minerals into layers during end members each of which has a distinct origin and solution and reprecipitation characteristics the first results from varied rates of

unexpected covariant behavior of the aegean and ionian seas in the period 1987 2008 by means of a nondimensional sea surface height index

mediterranean sea large scale low frequency ocean variability and water mass formation rates from 1987 to 2007 a retrospective analysis abstract we describe a synthesis of the mediterranean sea circulation structure and dynamics from a 23 year long reanalysis of the ocean circulation carried out by adani et al 2011 this mesoscale permitting dynamical reconstruction of past ocean variability in the mediterranean sea allows the study of the time mean circulation and its low frequency decadal components it is found that the time mean circulation is composed of boundary and open ocean intensified jets at the border of cyclonic and anticyclonic gyres the large scale basin circulation is generally characterized in the northern regions by cyclonic gyres and in its southern parts by anticyclonic gyres and eddy dominated flow fields with the exception of the tyrrhenian and the northern ionian sea the time mean tyrrhenian sea circulation is dominated by cyclonic gyres of different intensity and intermittency the northern ionian sea circulation however reverses in sign in two ten year periods the first in 1987 1996 and the second in 1997 2006 which is here called the northern ionian reversal phenomenon this reversal is provoked by the excursion of the atlantic ionian stream from the middle to the northern parts of the basin the decadal variability of other parts of the basin is characterized by changes in strength of the basin scale structures the water mass formation rates and variability are dominated by event like periods where the intermediate and deep waters are formed for 2 3 years at higher rates the largest deep water formation events of the past 23 years occurred separately in the western and eastern mediterranean basin the first coincided with the eastern mediterranean transient roether et al 1996 and the second with the western mediterranean deep water formation event in 2005 2006 smith et al 2008 a new schematic of the basin scale circulation is formulated and commented

geochemistry of dendritic anorthosites and associated pegmatites in the skaergaard intrusion east greenland evidence for metasomatism by a chlorine rich fluid abstract in the upper zone uza of the skaergaard intrusion dendritic anorthosites and pegmatites are found in a zone of deformed gabbro along the flank of a trough banded structure apatite biotite some having over 2 wt c1 and amphibole have higher chlorine contents than those found in the surrounding rocks and indicate the presence of a high temperature aqueous fluid having a high hcl hf fugacity ratio the fluid must have been derived locally by exsolution of magmatic volatiles because hydrous minerals in nearby hydrothermal veins have low chlorine contents and the structures are far from the margin of the intrusion apatite and quartz in the pegmatites have abundant fluid inclusions containing cubic halide crystals giving evidence for a separate aqueous fluid coexisting with an evolved residual melt the pegmatites are also characterized by mafic and felsic clots with compositions similar to immiscible silicate liquids dendritic anorthosites have equal or higher abundances of zr hf ta and rare earth elements than the surrounding gabbros yet they contain little pyroxene or fe ti oxides the unusual trace element enrichment patterns and the associated rare assemblage of zirconolite zircon baddeleyite and allanite suggest that the chlorine rich fluid was enriched in trace elements derived from the residual melt and the reacted mafic minerals deformation of the magma at a crystallinity below the critical melt fraction resulted in localized exsolution and channeling of a magmatic aqueous fluid and an evolved residual melt dissolution of pyroxene olivine and fe ti oxides allowed for further deformation and expulsion of the mafic melt leaving a plagioclase rich residue these structures are the product of enhanced reaction locally of an aqueous fluid which may have moved upward as a nearly planar reactive front throughout the lower crystallization zone in addition to the transport of trace elements migration of a high temperature fluid through the zone of crystallization could aid in the compaction of igneous cumulates and the development of layering this study presents the first evidence for a high temperature chlorine rich aqueous fluid in the layered series of the skaergaard intrusion and illustrates the important effect of such fluids on the physical and chemical evolution of layered intrusions

on the relationship between the decadal oscillations of the northern ionian sea and the salinity distributions in the eastern mediterranean 1 we study the impact of decadal inversions of the ionian upper layer circulation denominated as adriatic ionian bimodal oscillation system on thermohaline properties of the levantine and cretan seas lagrangian drifter data and surface geostrophic currents show that the atlantic water aw flow is well organized and most intense when the ionian circulation is cyclonic during the ionian anticyclonic phase the aw spreading pathway is the longest contributing to its prolonged mixing and higher salinity once it reaches the levantine thus the levantine basin is subject to less dilution by aw during the anticyclonic surface circulation phase empirical orthogonal function analysis of the sea level shows a large amplitude circular feature in the northern ionian which matches the cyclonic anticyclonic gyre obtained from lagrangian measurements furthermore it reveals the out of phase variability of the north ionian gyre and the aegean and levantine sea levels we further show that the surface salinity of the levantine basin variation is out of phase with that of the ionian surface layers salinity variations of the deepwater column in the aegean are out of phase with the ionian surface salinity values owing probably to a fast transfer of the surface salinity changes via winter deep convection the changing of the levantine and cretan seas salinity parallel to the ionian circulation inversions suggests that the preconditioning for the eastern mediterranean transient emt is driven by internal processes as the ionian inversions are cyclical events we conclude that the emt is not an isolated episode but potentially a recurrent phenomenon

causes of high crustal conductivity beneath the iapetus suture zone in great britain summary two magnetic variation anomalies in southern scotland and northern england have been linked to the position of the iapetus suture previous magnetotelluric measurements along a 140 km profile that crosses both anomalies have been supplemented by new high quality broad band observations groom bailey decomposition of the impedance and hypothetical event analysis of the magnetic variation data agree in defining different strike directions for the two halves of the mt profile n50 e for the northern part over the southern uplands and n90 e for the southern part over the northumberland trough te and tm mode apparent resistivity and phase data at representative frequencies have been inverted for the two sub profiles separately using the smooth inverse of smith booker 1990 the uppermost layer has a low resistivity is variable in thickness and correlates well with the known position and thickness of carboniferous sedimentary rocks the second layer has a very high resistivity thousands of m and reaches the surface where the lower palaeozoic metamorphic rocks of the southern uplands crop out a relatively rapid transition to low resistivities occurs at depths of between 8 and 16 km the conducting layer appears to be quasi continuous but where the profile crosses the anomalies identified by magnetic variation measurements the conductance increases and the upper surface is shallower the spatial coverage of the magnetic variation data has enabled us to extrapolate conductive features away from the line of section and project the electrical image onto the nec vertical incidence seismic reflection profile in the north sea there is excellent agreement between a number of features in the acoustical and electrical images the shallowing of the low resistivity layer to form a narrow wedge like feature corresponds to the offshore position of the stublick fault while to the north of the fault the top of the layer coincides with a south dipping reflector thought to be a thrust however the zones of high conductance and high lower crustal reflectivity do not in general correlate the good conductor beneath he northumberland trough spans two zones which were differentiated on ihe nec profile in terms of their reflectivity the shape of the conductor s upper surface in the vicinity of the stublick fault agrees well with the model of chadwick holliday 1991 who proposed that the iapetus suture was a whole crustal shear with a gently dipping central ramp the coincidence between the present day low resistivity layer and a surface of weakness that was active 300 400 myr ago is much more readily explained in terms of mineralogy the presence of graphite than the presence of fluids there is also strong support for interpreting the northern conductor in the same way its upper surface is relatively flat and occupies the position predicted as the horizontal detachment surface over which wedges of the southern uplands rocks were thrust its northeastward extension is sampled by a group of carboniferous vents from which xenolith suites of crust and upper mantle origin have been obtained the middle to upper crust is believed to be represented by quartzo feldspathic gneisses that contain abundant graphite

a synthesis of the ionian sea hydrography circulation and water mass pathways during poem phase i abstract in this paper we revisit with a thorough in depth analysis the dataset collected in the hydrographic surveys of the international collaborative programme poem physical oceanography of the eastern mediterranean in the period 1986 1987 the work has two major objectives the first is to refine the dynamic picture of the ionian upper thermocline sub basin scale circulation rather less definitive than the dynamic picture of the levantine sea circulation the second is to identify the pathways of the major water masses of the basin not only in the near surface but also in the intermediate and deep layers to our knowledge this is the first work defining the pathways of the levantine intermediate water liw and of the adriatic deep water adw eastern mediterranean deep water emdw that characterize the intermediate and deep circulations the major novel results can be summarized as follows in the upper thermocline 1 the atlantic ionian stream ais jet entering the sicily straits bifurcates into two main branches at 37 n 17 e it advects the modified atlantic water maw into the ionian sea interior the first branch turning directly southward encloses an overall anticyclonic area comprising multiple centers around which the maw is advected 2 the second ais branch extends further into the northeastern ionian where it too turns southward before crossing the entire ionian sea meridionally advecting maw on its left side and ionian surface water isw on its right this branch of the jet is confined to the ionian margin and does not pass around the pelops gyre 3 a new water mass the lsw is formed in the levantine basin and enters the cretan passage then is first veered cyclonically south of crete by the cretan gyre and successively is entrained anticyclonically around the pelops gyre and then enters the aegean sea 4 a permanent cyclone located in the northeastern ionian determines the pathway of mixed adriatic surface water ionian surface water asw isw 5 a permanent cyclone is found in all the surveys near the tip of the italian boot this novel analysis of the liw pathways shows that 1 the major source of intermediate liw during the period 1986 1987 was actually in the levantine sea liw formed there entered the cretan passage was veered cyclonically by the cretan gyre south of crete and then entered the southern ionian sea the major liw pathway was westward directly to the sicilian straits 2 secondary important liw pathways were determined by the interior structures the strong pelops anticyclone was entraining liw around its periphery and was determining the liw northward pathway that closely followed the eastern greek coastline it was along this pathway that liw entered the otranto strait a further branch of liw was entrained and recirculated around the multiple ionian anticyclones ia of the western ionian sea 3 the cretan cyclone is a feature confined to the upper thermocline intermediate layer it disappears at 400 dbar while the pelops anticyclone is strongly barotropic below the upper 100 dbar and penetrates quite intense down to 800 dbar 4 a further completely novel result concerns the new water mass found in the deep layer that spreads on the 29 15 kg m3 isopycnal surface this water mass characterized by high salinity and high oxygen content is formed inside the aegean sea and is observed to spread out all around the cretan arc straits the final fully novel result is the demonstration of a second pathway for the adw exiting from the otranto strait that is transformed into emdw and occupies the abyssal layers of the ionian sea interior the traditional pathway for emdw is along the isobaths along the western side of italy but adw was observed to be exiting from the otranto strait in the eastern hellenic trench at 39 5 n both during poem on86 and poem as87 this second pathway for emdw follows isobath contours along the western side of greece the two emdw routes converge and merge between 36 n and 35 n so producing a deep layer of emdw that occupies uniformly the abyssal plain of the interior of the ionian sea

electromagnetic precursors to earthquakes in the ulf band a review of observations and mechanisms despite over 2 decades of international and national monitoring of electrical signals with the hope of detecting precursors to earthquakes the scientific community is no closer to understanding why precursors are observed only in some cases laboratory measurements have demonstrated conclusively that self potentials develop owing to fluid flow and that both resistivity and magnetization change when rocks are stressed however field experiments have had much less success many purported observations of low frequency electrical precursors are much larger than expectations based on laboratory results in some cases no precursors occurred prior to earthquakes or precursory signals were reported with no corresponding coseismic signals nonetheless the field experiments are in approximate agreement with laboratory measurements maximum resistivity changes of a few percent have been observed prior to some earthquakes in china but the mechanism causing those changes is still unknown anomalous electric and magnetic fields associated with fluid flow prior to earthquakes may have been observed finally piezomagnetic signals associated with stress release in earthquakes have been documented in measurements of magnetic fields

transient eastern mediterranean deep waters in response to the massive dense water output of the aegean sea in the 1990s abstract we present a detailed account of the changing hydrography and the large scale circulation of the deep waters of the eastern mediterranean emed that resulted from the unique high volume influx of dense waters from the aegean sea during the 1990s and of the changes within the aegean that initiated the event the so called eastern mediterranean transient emt the analysis uses repeated hydrographic and transient tracer surveys of the emed in 1987 1991 1995 1999 and 2001 2002 hydrographic time series in the southern aegean and southern adriatic seas and further scattered data aegean outflow averaged nearly 3 10 6 m 3 s 1 between mid 1992 and late 1994 and was largest during 1993 when south and west of crete aegean influenced deep waters extended upwards to 400 m depth emt related aegean outflow prior to 1992 confined to the region around crete and to 1800 m depth wise amounted to about 3 of the total outflow outflow after 1994 up to 2001 2002 derived from the increasing inventory of the tracer cfc 12 contributed 20 to the total of 2 8 10 14 m 3 densities in the southern aegean sea deep waters rose by 0 2 kg m 3 between 1987 and 1993 and decreased more slowly thereafter the aegean waters delivered via the principal exit pathway in kasos strait east of crete propagated westward along the cretan slope such that in 1995 the highest densities were observed in the hellenic trench west of crete aegean influenced waters also crossed the east mediterranean ridge south of crete and from there expanded eastward into the southeastern levantine sea transfer into the ionian mostly followed the hellenic trench largely up to the trench s northern end at about 37 n from there the waters spread further west while mixing with the resident waters additional transfer occurred through the herodotus trough in the south levantine waters after 1994 consistently showed temperature salinity t s inversions in roughly 1000 1700 m depth with amplitudes decreasing in time the t s distributions in the ionian sea were more diverse one cause being added aegean outflow of relatively lower density through the antikithira strait west of crete spreading of the aegean influenced waters was quite swift such that by early 1995 the entire emed was affected and strong mixing is indicated by near linear t s relationships observed in various places referenced to 2000 and 3000 dbar the highest aegean generated densities observed during the event equaled those generated by adriatic sea outflow in the northern ionian sea prior to the emt a precarious balance between the two dense water source areas is thus indicated a feedback is proposed which helped triggering the change from a dominating adriatic source to the aegean source but at the same time supported the previous long year dominance of the adriatic the emed deep waters will remain transient for decades to come

on the salinity structure in the south adriatic as derived from float and glider observations in 2013 2016 abstract between 2013 and 2016 a drastic change in the vertical salinity structure in the south adriatic pit was recorded by argo floats and ocean gliders the analysis revealed that high salinity waters characterised 2013 at the surface and intermediate layers creating the conditions for dense water formation the year 2014 was instead marked by less saline water dominant in the first 100 m that spread in the entire pit heat gain negative e p anomalies and abundant river runoff during that period maintained this saline stratification for more than a year this water mass contributed to the dilution of the underlying layer during the convection event of 2015 the spring transition period later in 2015 as defined by new saline water placed over the winter formatted water mass and the unperturbed part of the existent salinity profile in the deeper layers resulted in a particular vertical structure characterised by a double salinity maximum high salinity waters continued to be present at the surface and intermediate layers until the end of 2016 when the strong convection led to a deep mixing eliminating that structure the analysis of the available datasets in the south adriatic pit since 1984 linked the presence of these high salinity waters with the cyclonic phase of the north ionian gyre additionally revealing also years of a decreasing trend during the anticyclonic mode of the gyre

can internal processes sustain reversals of the ocean upper circulation the ionian sea example 1 in 1997 an inversion in the ionian upper layer circulation was documented and ascribed to a massive inflow of aegean dense waters associated with the eastern mediterranean transient emt and not to the wind stress borzelli et al 2009 here we generalize the concept hypothesizing that such inversions are possible even in the absence of the aegean influence indeed salinity and density data collected in the southern adriatic the main source of the eastern mediterranean deep water show decadal variations coherent with changes in the sea level height in the northern ionian scaling considerations suggest that the redistribution of ionian water masses resulting from changes in the thermohaline properties of waters entering the basin can sustain inversions of the upper layer circulation therefore we propose a feedback mechanism named the adriatic ionian bimodal oscillating system bios between variations in the thermohaline properties of waters formed in the southern adriatic and the ionian circulation

the cumulate paradigm reconsidered the cumulate terminology outlined by wager and coworkers provided a logical system for describing the textures of the rocks of layered intrusions but recent work shows that this model fails to accommodate all the processes responsible for the petrographic features of coarse grained rocks textures of adcumulates and orthocumulates in the skaergaard intrusion cannot be correlated with concentrations of incompatible elements representing trapped liquid compaction and open system percolative processes have altered their textures modes and even bulk compositions although a rock may be a cumulate in the absence of other evidence it can be misleading to refer to it in terms of the cumulate nomenclature

the origin of laminated and massive anorthosite sept iles layered intrusion quebec canada well laminated plagioclase rich rocks anorthosite occur as layers in mineralogically similar but massive rocks in the sept iles intrusion several phases of crystallization of poikilitic clinopyroxene have preserved the intermediate stages in the production of these rocks plagioclase nucleated and initially grew in random orientations in the stationary part of the boundary layer there in the absence of other events crystallization produced the massive anorthosite the laminated anorthosite may have been produced by episodic increases in the velocity of the magma adjacent to the boundarylayer induced by magmatic density currents such currents would have caused the zone of simple shear of the boundary layer to migrate outwards into the previously stationary part this simple shear would then have rotated the existing plagioclase crystals as well as crystals that nucleated at that time towards the shear plane some rocks show evidence of several periods of enhanced flow velocities the production of the lamination may have weakened the crystal mush and enabled slumping to occur producing folds and contorted layers finally compaction liberated large quantities of intercumulus magma of which some was trapped as granophyric segregations and some escaped by overturing and churning the crystal pile earlier formed granophyric segregations and laminated layers were disrupted during this process to produce a range of more complex rocks including igneous breccias

mesoscale variability in denmark strait the pv outflow hypothesis abstract the outflow through denmark strait shows remarkable mesoscale variability characterized by the continuous formation of intense mesoscale cyclones just south of the sill these cyclones have a diameter of about 30 km and clear signatures at the sea surface and in currents measured near the bottom they have a remnant of arctic intermediate water aiw in their core the authors hypothesis is that these cyclones are formed by stretching of the high potential vorticity pv water column that outflows through denmark strait the light upper layer of the outflow the east greenland current remains on the surface in the irminger sea while the dense overflow water descends the east greenland continental slope the midlevel waters mostly aiw could thus be stretched by more than 100 which would induce very strong cyclonic relative vorticity the main test of this new hypothesis is by way of numerical experiments carried out with an isopycnal coordinate ocean model configured to have a marginal sea

eastern mediterranean transient and reversal of the ionian sea circulation 1 maps of the remotely sensed absolute dynamic topography adt and sea surface temperature sst over the eastern mediterranean in the period june 1993 to june 2001 show a dramatic and sudden change in the sea surface structure this change which is presumably associated with the relaxation of the eastern mediterranean transient emt had taken place by the middle of 1997 and consisted of a complete reversal of the ionian upper layer circulation from anticyclonic to cyclonic in the emt phase sst and adt maps suggest enhanced communication between the ionian and the aegean basins as well as aegean waters spreading northward along the eastern ionian flank negative wind vorticity in the ionian suggests that the switch of the upper layer circulation from anticyclonic to cyclonic cannot be explained in terms of the wind forcing therefore we suggest the predominance of the baroclinic vorticity production term in determining the upper layer circulation inversion

dicing with earthquakes the van group have been publicizing claims to be predicting earthquakes since 1981 their predictions of two basic parameters of earthquakes magnitude and location are very loosely constrained most van magnitude predictions are below 5 7 ms with a tolerance of 0 7 ms the uncertainty range spanned by a predicted magnitude is so enveloping that such forecasts cannot be viewed as plainly successful in terms of van s claims to spatial resolution these if successful might constrain the linear dimension of the source region of a magnitude 8 0 ms earthquake but do not adequately constrain a magnitude as large as 7 5 ms not only do van need to refine the tolerances in their magnitude and location predictions before careful judgements can be made but it is also necessary to provide an unambiguous statement of the prediction hypothesis used in relation to a pre published and communally archived dataset of complete seismic electric signal occurrences similar to seismological station bulletins

evidence for the influence of atlantic ionian stream fluctuations on the tidally induced internal dynamics in the strait of messina abstract on 24 and 25 october 1995 high resolution oceanographic measurements were carried out in the strait of messina by using a towed conductivity temperature depth chain and a vessel mounted acoustic doppler current profiler during the period of investigation the surface water of the tyrrhenian sea north of the strait sill was heavier than the surface water of the ionian sea south of the strait sill as a consequence during northward tidal flow surface water of the ionian sea spread as a surface jet into the tyrrhenian sea whereas during southward tidal flow heavier surface water of the tyrrhenian sea spread after having sunk to a depth of about 100 m as a subsurface jet into the ionian sea both jets had the form of an internal bore which finally developed into trains of internal solitary waves whose amplitudes were larger north than south of the strait sill these measurements represent a detailed picture of the tidally induced internal dynamics in the strait of messina during the period of i