intra annual variation of wave number 4 structure of vertical e b drifts in the equatorial ionosphere seen from rocsat 1 1 this paper studies the intra annual variation of the wave number 4 structure in the equatorial vertical e b drifts at high solar flux level based on of the rocsat 1 observations during the interval from 1999 to 2004 it is found that the daytime longitudinal structure is significant in northern summer and early autumn but weak in northern winter this is consistent with the intra annual variations of the tidal mode de3 at night the intra annual variation of the wave number 4 structure shows some differences from that in daytime which may relate to different dynamo mechanisms operating in different local time we also found that the wave number 4 structure mainly shifts eastward during daytime in most of months which is coincident with the eastward propagation of the de3 tide however it is largely disturbed near sunrise and sunset we attribute this disturbance as the jumping of the main dynamo region between e and f layers as well as the different dynamo mechanisms in different dynamo regions

seismogenic sources potentially responsible for earthquakes with m 6 in the eastern southern alps thiene udine sector ne italy summary new geomorphological and structural data permitted to define the active faulting framework of the eastern southern alps ne italy all the active faults detected in the investigated area are thrust segments of the complex thrust system which has been responsible for the latest building of the eastern southalpine chain esc geomorphological investigations were performed to identify the surficial traces of recent fault activity generally represented by gentle scarps connecting uplifted palaeolandscapes of quaternary age with the flat and lower areas of the venetian and friulian plains surficial and subsurficial data the latter from reflection seismic profiles available for the investigated faults indicate that the thrusts have been responsible for the displacement of the entire wedge of quaternary deposits in the western sector of the investigated area the six recognized fault segments represent portions of a 100 km long thrust system at the boundary between the alpine relief and the plain areas in the eastern sector active tectonics is the result of parallel thrust segments located both in the alpine mountainous area and in the friulian plain the 3 d geometry of the active thrust segments has been derived from new structural surficial surveys and the interpretation of reflection seismic profiles for a total length of 1700 km on this basis we defined the geometry of 10 seismogenic sources whose dimensions are consistent with the occurrence of earthquakes with m 6 the comparison between the source geometry and the highest intensity data point distribution of large historical earthquakes has permitted to make hypotheses on the association of past seismic events to specific seismogenic sources this procedure indicated that no large historical events can be attributed to three sources montello conegliano arba ragogna medea this may indicate an elapsed time since the last activation of more than eight centuries based on the completeness of the historical catalogues the available data define therefore sources and related areas for which a high level of seismic hazard may be invoked

advection of fluids at the front of the sicilian neogene subduction complex abstract the sicilian accretionary prism shows a large southward imbricated system of thrust sheets the frontal part of the belt has been tectonically emplaced in plio pleistocene times major decollement surfaces and sole thrusts at the base of and inside the prism consist of melanges with a blocks in matrix fabric in the frontal part two superposed decollement levels are recognized the upper one located at the base of the paleogene neogene sedimentary series and the basal one at the base of duplexes triassic miocene sedimentary series syntectonic dewatering of the sedimentary sections occurred along decollements and thrust faults involving hydrofracture and mineralized vein development inside the deep sole thrusts rooted in the basal decollement hydrofractured blocks show different generations of syntectonic quartz and calcite extensional veins while in the upper decollement only calcite veins have been observed both quartz and calcite veins show aqueous primary fluid inclusions of low salinity with low trapping temperature for fluids in the upper decollement if we assume that at the time of deformation the main heat source was the regional conductive geothermal gradient the trapping temperatures of the fluids inside veins of the deep sole thrusts are higher than those predicted by the pilo pleistocene gradient for this subduction zone and correspond to a thermal anomaly we suggest that the frontal sicilian prism supported localized transient fluid flow of deep freshwater sourced from two different origins a shallow one for fluids now trapped in the upper decollement and a deep internal origin 6 10 km minimum depth for the hot fluids channelized along the basal decollement and now trapped inside the sole thrust of the mt scalpello duplex area

transverse versus longitudinal extension in the foredeep peripheral bulge system role of cretaceous structural inheritances during early miocene extensional faulting in inner central apennines belt this study reports on the rocca di cave extensional fault system which is located in the prenestini mountains central italy of the apennines fold and thrust belt and presently represents the oldest exposure of early orogenic foreland fault system of the apennines this fault system was oriented perpendicular to the strike of the foredeep peripheral bulge system indicating that the onset of convergence was marked by a foredeep parallel extension instead of the commonly observed foredeep perpendicular stretching associated with lithosphere flexuring the studied fault system is formed by a 10 km long and 2 km wide e w elongated area that includes two mutually orthogonal sets of faults oriented about e w and n s respectively e w and mainly n s striking faults developed during a preorogenic santonian to campanian in age e w oriented extension kinematics which caused first uplift and erosion and then drowning of the cretaceous carbonate platform and the onset of a pelagic environment both fault sets were later reactivated in the early miocene when the area was forming part of the foreland region ahead of the eastward migrating apennines fold and thrust belt and was undergoing local n s oriented i e foredeep parallel stretching this extensional stage implied the sedimentation of hundreds of meters of synkinematic strata in the northern block of the rocca di cave fault system coevally with episodes of subaerial erosion in areas of the southern block further extensional and right lateral reactivation of inherited faults occurred in the late miocene during the progressive incorporation of the area into the apennines belt

longitudinal variations in the f region ionosphere and the topside ionosphere plasmasphere observations and model simulations 1 constellation observing system for meteorology ionosphere and climate cosmic observations of the total electron content tec above and below 800 km are used to study the local time and seasonal variation of longitude structures in both the f region ionosphere as well as the topside ionosphere and plasmasphere the cosmic observations reveal the presence of distinct longitude variations in the topside ionosphere plasmasphere tec and these further exhibit a seasonal and local time dependence the predominant feature observed at all local times in the topside ionosphere plasmasphere tec is a substantial maximum minimum during northern hemisphere winter summer around 300 360 geographic longitude around equinox at a fixed local time a wave 4 variation in longitude prevails in the daytime f region tec as well as the topside ionosphere plasmasphere tec the wave 4 variation in longitude persists into the nighttime in the f region however the nighttime topside ionosphere plasmasphere tec exhibits two maxima in longitude the cosmic observations clearly reveal the presence of substantial longitude variations in the f region and topside ionosphere plasmasphere and to elucidate the source of the longitude variations results are presented based on the coupling between the global ionosphere plasmasphere model and the thermosphere ionosphere electrodynamics general circulation model the model simulations demonstrate that the orientation of the geomagnetic field plays a fundamental role in generating significant longitude variations in the topside ionosphere plasmasphere but does not considerably influence longitude variations in the f region ionosphere the model results further confirm that nonmigrating tides are the primary mechanism for generating longitude variations in the f region ionosphere the coupled model additionally demonstrates that nonmigrating tides are also of considerable importance for the generation of longitude variations in the topside ionosphere plasmasphere tec

dynamic development of fault rocks in a crustal scale detachment an example from western norway 1 the nordfjord sogn detachment nsd zone of western norway juxtaposes eclogites and gneisses of lower crustal affinity with sedimentary deposits suggesting that the zone experienced substantial displacement during devonian extensional denudation of the caledonides renewed activation occurred in permian and jurassic cretaceous times the detachment zone consists of a succession of fault related rocks reflecting various crustal positions and deformation mechanisms during activation and unroofing in more detail the lower 1 2 km thick section of the nsd zone consists of mylonites with various protoliths showing a general upward decrease in metamorphic grade the mylonitic section is truncated by the nsd fault defining the boundary toward hanging wall nappe rocks that are topped by sedimentary basins in an attempt to provide precise descriptions of the observed fault rocks we classify these rocks into 1 noncohesive breccias 2 cemented and indurated breccias of secondary cohesion and 3 cataclasites phyllonites and mylonites formed with primary cohesion along and across strike sections of the fault reveal the spatial and temporal relationships of the nsd fault the fault zone consists of a lower section of phyllonites and cataclasites reaching a total thickness of 50 70 m significant volumes of pseudotachylyte were injected into these fault rocks and were later reworked reactivation of the fault is suggested by overprinting carbonate cemented breccias that are cut by a discrete fault itself associated with breccias and gouge by comparing the various fault rocks and their formation mechanisms some constraints can be applied to the unroofing history the nsd fault developed in the ductile brittle transition zone of the crust where it experienced an initial shift from mainly frictional to plastic flow caused by reaction softening before hardening caused a return to frictional flow at the same time repeated pulses of pseudotachylyte were generated possibly lubricating the fault zone and contributing to strain localization these pseudotachylyte pulses also show that the fault was affected by seismic slip events before returning to a creep regime within a wider section than that ruptured by earthquakes younger cemented breccias and noncohesive breccias and gouge reflect earthquake rupturing and frictional flow within the seismogenic crust

microtectonics of low p low t carbonate fault rocks abstract with the aim of deducing some general microtectonic processes responsible for the development of carbonate fault cores rock samples were collected in ten of such structures which are different in size attitude kinematics displacement and tectonic environment samples were thin sectioned and analysed under an optical microscope microscopic evidence i e at the scale of tens to hundreds of microns shows that grain size reduction occurred mostly by cataclasis and occasionally by pressure solution cataclasis involved three main processes here named intragranular extension fracturing chipping and shear fracturing intragranular extension fracturing is more common in the early stages of cataclasis and produces a coarse breccia consisting of angular grains in a few cases pre existing weaknesses and flaws control the fracture pattern associated with intragranular extension fracturing chipping is more common in the advanced stages of cataclasis and produces a gouge consisting of a few survivor rounded grains within a fine matrix shear fracturing seems less frequent than the other two processes and usually occurs in the advanced stages of cataclasis by considering the microscopic and mesoscopic evidence and the dissimilar frequency of dissolution structures in the analysed fault cores and damage zones it is inferred that the studied fault zones probably acted as conduit barrier permeability systems

kinematics seismotectonics and seismic potential of the eastern sector of the european alps from gps and seismic deformation data abstract we present a first synoptic view of the seismotectonics and kinematics of the eastern sector of the european alps using geodetic and seismological data the study area marks the boundary between the adriatic and the eurasian plates through a wide zone of deformation including a variety of tectonic styles within a complex network of crustal and lithospheric faults a new dense gps velocity field new focal mechanisms and seismic catalogues with uniformly re calibrated magnitudes from 1005 are used to estimate geodetic and seismic deformation rates and to develop interseismic kinematic and fault locking models kinematic indicators from seismological and geodetic data are remarkably consistent at different spatial scales in addition to large scale surface motion gps velocities highlight more localized deformation features revealing a complex configuration of interacting tectonic blocks for which new constraints are provided in this work accounting for elastic strain build up at faults bonding rotating blocks the geodetic and seismological data highlight two belts of higher deformation rates running wsw ene along the eastern southern alps esa in italy and e w in slovenia where deformation is more distributed the highest geodetic strain rates are observed in the montello cansiglio segment of the esa thrust front for which the higher density of the gps network provides indications of limited interseismic locking most of the dextral shear between the eastern southern alps and the eastern alps blocks is accommodated along the fella sava fault rather than the periadriatic fault in northern croatia and slovenia geodetic and seismological data allow constraining the kinematics of the active structures bounding the triangular shaped region encompassing the sava folds which plays a major role in accommodating the transition from adria to pannonian like motion trends the analysis of the seismic and geodetic moment rates provides new insights into the seismic potential along the esa front

three dimensional segmentation and different rupture behavior during the 2012 emilia seismic sequence northern italy describing the slip behavior of an active fault system is central to understanding the seismic potential of seismogenic areas different elements control the nature and the extent of the coseismic and post seismic ruptures including the geometry of faults the nature of faulted rocks and the stress changes caused by the mainshocks in may june 2012 a severe seismic sequence struck a portion of the po plain northern italy where a thick blanket of plio quaternary sediments hides a number of seismogenic sources corresponding to the external thrust systems of the northern apennines we used deep seismic reflection data to reconstruct the geometry of the faults responsible for the sequence these faults exhibit significant non planarity due to tectono stratigraphic heterogeneities inherited from a complex pre thrusting extensional tectonic phase a comparison of the fault parameters derived from our geological analysis and the evidence supplied by seismological aftershock distributions and geodetic data insar allowed to identify the causative fault segments of the two mainshocks we then modeled the coulomb stress changes produced by two mainshocks to analyze on and off fault seismicity discrepancies between the magnitude of the earthquakes and the extent of active faults suggest that the mainshocks did not rupture the entire thrust planes we contend that seismogenic ruptures were confined in the mesozoic carbonates and were stopped by lithological changes and or mechanical complexities of the fault planes both along dip and along strike our findings highlight that along the active structures of the po plain slip tends to be seismogenic where faults are located in mesozoic carbonate rocks

fracture controlled fluid circulation and dissolutional weathering in sinkhole prone carbonate rocks from central italy abstract fractures karstic cavities and calcite precipitates are analysed on mesozoic carbonate strata from the cornicolani mountains central italy to quantify the relationships between fractures and related karstic cavities and to infer the fracture controlled fluid pathways the study area is characterized by active sinkholes and other karstic caves which are among the deepest ones in the world results show a clear control of fractures on the process of dissolutional weathering and therefore on the fluid circulation a model is proposed in which two different modes of dissolutional weathering coexist i a mode of diffuse weathering consisting in the dissolutional enlargement of closely spaced joints and bedding surfaces this process affects the strata situated at depths of up to 5 m ii a mode of more concentrated weathering active along highly permeable fault damage zones at depths of at least 70 m these processes are mostly connected with the shallow circulation of calcite dissolving meteoric waters and are controlled by the disparity of permeability between the fault damage zones and the surrounding jointed strata some calcite precipitates along the studied fault damage zones may be connected with a dissolutional process operated by waters that interacted with the adjacent quiescent volcanic district such calcite dissolving waters and the presence of high permeable fault damage zones along which the waters may ascent are probably the cause for the development of some of the deep sinkholes along faults in the study area

longitudinal variation of the e region electric fields caused by atmospheric tides 1 polarization electric fields created by the e and f region dynamos cause the uplift of f region plasma the subsequent redistribution of that plasma along the magnetic field lines creates the equatorial ionospheric anomaly eia observations of the post sunset eia made by the image and timed satellites are compared here with champ orsted and sac c observations of the noontime equatorial electrojet eej during magnetically quiet periods around equinox the eia and eej show a remarkably similar four peaked wave like longitudinal variation its structure is consistent with the longitudinal variation in the strength of diurnal tides that drive the e region dynamo this indicates a strong vertical coupling between the ionosphere and troposphere because the four peaked tidal structure is driven by tropospheric weather furthermore the dayside ionospheric conditions are found to perform the global scale longitudinal structure of the post sunset ionosphere at low latitudes

signature of coseismic decarbonation in dolomitic fault rocks of the naukluft thrust namibia unequivocal geological signatures of seismic slip are rare exceptionally so in carbonate hosted faults where carbonate minerals dissociate at temperatures lower than those required for producing a friction melt this thermal dissociation leads to significant fault weakening by increased fluid pressure and or nanoparticle lubrication preventing further heating of the fault surface pseudotachylyte is therefore unlikely to form in carbonate hosted faults and other evidence for seismic slip must be identified we studied the lower cambrian naukluft thrust which crops out in central namibia it contains a cataclastic dolomite fault rock referred to as gritty dolomite which we interpret as a signature of coseismic carbonate dissociation and subsequent fluid rock interactions the fault was active at ambient temperatures below 2001c gritty dolomite contains rounded low aspect ratio dolomite clasts with a uniform fe rich dolomite coating euhedral to subhedral magnetite quartz and k feldspar in a fine grained massive to laminated carbonate matrix of particulate dolomite and crystalline calcite cement the fault rock texture combined with evidence of injectites of gritty dolomite into the wallrock indicates the cataclasite deformed as a fluidized granular flow at seismic slip velocities frictional heating caused dissociation of dolomite to co 2 and ca fe and mg oxides this release of co2 decreased the ph of the pore fluid in the fault causing dissolution and rounding of dolomite clasts within an inertial grain flow and precipitation of carbonate coatings and euhedral silicates and oxides during subsequent cooling and co2 escape examples of similar rocks having some if not all of these characteristics have been described from other carbonate hosted faults the geological setting of the naukluft thrust is unique in spatial extent and quality of exposure allowing us to eliminate alternative hypotheses for sources of co2 to drive fluidization

strain accumulation in the southern alps ne italy and deformation at the northeastern boundary of adria observed by cgps measurements 1 we use continuous gps observations to investigate the rate of strain accumulation in the area affected by the 1976 friuli earthquakes comparison between the motion predicted by the rigid rotation of adria and the shortening observed across the study area suggests that the 2 0 0 2 mm yr motion of adria is entirely absorbed in the southern alps through thrusting and crustal thickening with very little or no motion transferred to the north we use elastic dislocation modelling to investigate the rate of interseismic loading and the geometry of the shear zone at depth the best fit solution indicates that a northward dipping creeping dislocation whose edge is located within a 50 km wide area beneath the southern alps accomodates 2 1 0 5 mm yr of the adria motion limited resolution on locking depth acceptable values between 0 and 25 km and trade off between dip and slip do not allow a precise reconstruction of the dislocation geometry the range of acceptable model parameters is consistent with a 20 dipping dislocation locked above 10 km depth and slipping at 2 4 mm yr whose geometry is suggested by seismological informations

thermal decomposition along natural carbonate faults during earthquakes earthquake slip is facilitated by a number of thermally activated physicochemical processes that are triggered by temperature rise during fast fault motion i e frictional heating most of our knowledge on these processes is derived from theoretical and experimental studies however additional information can be provided by direct observation of ancient faults exposed at the earth s surface although fault rock indicators of earthquake processes along ancient faults have been inferred the only unambiguous and rare evidence of seismic sliding from natural faults is solidified friction melts or pseudotachylytes here we document a gamut of natural fault rocks produced by thermally activated processes during earthquake slip these processes occurred at 2 3 km depth along a thin 0 3 1 0 mm principal slip zone of a regional thrust fault that accommodated several kilometers of displacement in the slip zone composed of ultrafine grained fault rocks made of calcite and minor clays we observe the presence of relict calcite and clay numerous vesicles poorly crystalline amorphous phases and newly formed calcite skeletal crystals these observations indicate that during earthquake rupture frictional heating induced calcite decarbonation and phyllosilicate dehydration these microstructures may be diagnostic for recognizing ancient earthquakes along exhumed faults

interseismic coupling seismic potential and earthquake recurrence on the southern front of the eastern alps ne italy here we use continuous gps observations to document the geodetic strain accumulation across the south eastern alps ne italy we estimate the interseismic coupling on the intracontinental collision thrust fault and discuss the seismic potential and earthquake recurrence we invert the gps velocities using the back slip approach to simultaneously estimate the relative angular velocity and the degree of interseismic coupling on the thrust fault that separates the eastern alps and the venetian friulian plain comparison between the rigid rotation predicted motion and the shortening observed across the area indicates that the south eastern alpine thrust front absorbs about 70 of the total convergence between the adria and eurasia plates the coupling is computed on a north dipping fault following the continuous external seismogenic thrust front of the south eastern alps the modeled thrust fault is currently locked from the surface to a depth of 10 km the transition zone between locked and creeping portions of the fault roughly corresponds with the belt of microseismicity parallel and to the north of the mountain front the estimated moment deficit rate is 1 3 0 4 1017 nm yr the comparison between the estimated moment deficit and that released historically by the earthquakes suggests that to account for the moment deficit the following two factors or their combination should be considered 1 a significant part of the observed interseismic coupling is released aseismically and 2 infrequent large events with long return period 1000 years and with magnitudes larger than the value assigned to the largest historical events mw 6 7

wavenumber 4 patterns of the total electron content over the low latitude ionosphere 1 the global ionospheric maps gims produced by jpl are used to investigate the longitudinal structure of the low latitude ionosphere as a proxy of the ionization parameter at low latitudes the latitudinally integrated total electron content itec is first extracted from low latitude gims and then fourier filtered to obtain the wavenumber 4 components we then study in detail the diurnal seasonal and solar cycle variations of the wave patterns it is found that the wavenumber 4 patterns are intense and well developed in boreal summer and early boreal autumn but quite weak in boreal winter this seasonal variation is consistent with that of the zonal wind of the non migrating tide mode de3 we also found that the wavenumber 4 patterns shift eastward with a shifting speed that is smaller in daytime than at night this is attributed to the contribution of both the eastward propagation of de3 in e region and the zonal e b ion drifts in f region our results support the suggestion that the longitudinal wavenumber 4 structure of the low latitude ionosphere should be originated from the non migrating tide mode de3

connections between deep tropical clouds and the earth s ionosphere 1 we report on a series of simulations with the national center for atmospheric research ncar thermosphere ionosphere mesosphere electrodynamics general circulation model time gcm which were designed to replicate and facilitate the interpretation of the longitudinal structure discovered in image satellite airglow observations of the equatorial ionization anomaly eia at the far ultraviolet fuv 135 6 nm wavelength during march april 2002 equinox our time gcm results indicate that the four peaked longitudinal variation in the eia observed by image fuv near 20 00 local solar time can be explained by the effects of an eastward propagating zonal wavenumber 3 diurnal tide de3 that is excited by latent heat release associated with raindrop formation in the tropical troposphere

multistage strain localisation and fluid assisted cataclasis in carbonate rocks during the seismic cycle insights from the belluno thrust eastern southern alps italy abstract strain localisation in carbonate rocks impacts upon the nucleation and development of structures within the shallow seismogenic crust studying deformed carbonate rocks is thus a key to the refined understanding of the mechanical behaviour of rock successions with high potential to fail coseismically in response to stress accumulation we studied deformation structures and mechanisms of the miocene belluno thrust from the seismically active eastern southern alps italy the thrust contains several structural facies and features pressure soluted and veined lithons cataclasites s c fabrics principal slip surface which make it possible to define a sequence of deformation events in space and through time during thrusting image analysis of cataclasite particle size distribution and morphology supported by cathodoluminescence imaging indicates corrosive wearing as the main comminuting mechanism during cataclasis and repeated ingress of overpressured aqueous fluids promoting carbonate clast dissolution we propose an evolutionary scenario of multiple episodes of fabric formation and rejuvenation that localised and accommodated increasing shear strain into a progressively narrowing fault core we propose that strain localisation in carbonate rocks can be greatly facilitated by cyclic fluctuations between strain hardening and softening conditions punctuated by transient spikes of coseismic failure accommodated by cataclasis during the ingress of overpressured chemically reactive fluids that control carbonate precipitation and dissolution

tectonics of the dolomites southern alps northern italy abstract in post variscan times the dolomites underwent a number of tectonic events which may be summarized as follows permian and triassic rifting phases broke the area into n s trending basins with different degrees of subsidence a middle triassic transpressive event then deformed the region along a n70 e axis generating flower structures within the basement volcano tectonic domal uplift and subsequent caldera formation occurred at the same time as the late ladinian magmatism early jurassic rifting also controlled the subsidence which increased eastward this long period of deformation was followed by a pre neogene late cretaceous palaeogene e w ene wsw compression which generated a w vergent belt possibly equivalent to the folded foreland of the dinaric chain a 70 km e w section of the dolomites indicates shortening of at least 10 km during the neogene the dolomites as far north as the insubric lineament were the innermost part of a s vergent thrust belt the basement of the dolomites was thrust southwards along the valsugana line onto the sedimentary cover of the venetian prealps for at least 10 km this caused a regional uplift of 3 5 km the valsugana line and its backthrusts on the northern side of the central dolomites generated a 60 km wide pop up in the form of a synclinorium within which the sedimentary cover adapted itself mainly by flexural slip often forming triangle zones the shortening linked to this folding is about 5 km with neogene thrusts faulting and folding pre existing thrust planes on the north eastern side of the dolomites neogene deformation is apparently more strictly controlled by the transpressive effects of the insubric lineament and shortening of the sedimentary cover may be greater than in the central dolomites minor deformation linked to the giudicarie belt is present in the western dolomites the present structure of the dolomites is thus the result of a number of tectonic events of different significance and different strike only a 3 dimensional restoration can unravel the true structure of the dolomites

fluidization and melting of fault gouge during seismic slip identification in the nojima fault zone and implications for focal earthquake mechanisms 1 the record of physical processes that occur during seismic slip events is well preserved in fault rocks from the active nojima fault in japan the fault rocks formed at about 3 km depth and comprise thin alternating layers of very fine gouge and pseudotachylyte derived from granite each layer is thinner than a few millimeters and corresponds to one seismic slip event the very thin slip zone width suggests that some mechanisms of slip weakening operated and our studies of the fault rocks suggest that fluidization and melting of gouge were particularly important fluidized and nonfluidized gouges were distinguished using the detection probability of fragmented counterparts method it is known from granular material science that the phase transition from a grain friction regime to fluidization of granular materials can occur only by a very small decrease in volume fraction of solid grains once fluidization occurs the frictional resistance decreases abruptly to nearly zero even before thermal pressurization reaches its extreme state when fault gouge is melted frictional resistance is governed by the viscosity of melt which depends mainly on temperature chemical composition h2o concentration and the volume fraction of unmelted grains for each pseudotachylyte layer we estimated the temperature of melt using various temperature indices and measured volume fraction of unmelted grains we synthesized these data to reconstruct the change in viscosity during seismic slip events the melt viscosity is very high 107 9 pas during initial melting due to the combined effect of low temperature 750 800 c and large volume fraction of solid grains thus seismic slip is inevitably restrained instantaneously once this mechanical barrier is overcome the viscosity reduces continuously and dramatically as slip increases at 1000 c the viscosity reduces to 104pas and eventually to 10pas at 1280 c thus stress drops almost completely and rupturing tends to run away

longitudinal variations in the equatorial vertical drift in the topside ionosphere 1 the vertical ion drift is important for understanding and modeling the electrodynamics at low latitudes measurements from the ion drift meter on the defense meteorological satellite program dmsp f15 are used to examine longitudinal variations in the vertical ion drift at the dip equator in the topside ionosphere local time was restricted to 0930 and the data were organized by month for 2001 and 2002 two features were found contributing to the longitudinal variations in the electrodynamics meridional winds contribute to the equatorial vertical ion drift at the 830 km magnetic apex due to their dynamo action at the foot points of the magnetic field lines in the f region at magnetic latitudes near 15 electric fields producing a downward perturbation drift at 0930 are produced by hemispheric differences in the dynamo current due primarily to the different orientation of the magnetic meridian relative to the terminator this produces the seasonally dependent variation as a function of longitude that is observed a wavenumber 4 longitudinal variation also appears to be present throughout the year but is more influential during equinox conditions this variation also shows a seasonal cycle shifting east during northern summer and west during northern winter further analysis would be required to isolate the characteristics of a wavenumber 4 driver from the wavenumber 4 component of the fourier series used here to fit the data

the anatomy of the 2009 l aquila normal fault system central italy imaged by high resolution foreshock and aftershock locations 1 on 6 april 01 32 utc 2009 a mw 6 1 normal faulting earthquake struck the axial area of the abruzzo region in central italy we study the geometry of fault segments using high resolution foreshock and aftershock locations two main sw dipping segments the l aquila and campotosto faults forming an en echelon system 40 km long nw trending the 16 km long l aquila fault shows a planar geometry with constant dip 48 through the entire upper crust down to 10 km depth the campotosto fault activated by three events with 5 0 mw 5 2 shows a striking listric geometry composed by planar segments with different dips along depth rather than a smoothly curving single fault surface the investigation of the spatiotemporal evolution of foreshock activity within the crustal volume where the subsequent l aquila main shock nucleated allows us to image the progressive activation of the main fault plane from the beginning of 2009 the foreshocks activated the deepest portion of the fault until a week before the main shock when the largest foreshock mw 4 0 triggered a minor antithetic segment seismicity jumped back to the main plane a few hours before the main shock secondary synthetic and antithetic fault segments are present both on the hanging and footwall of the system the stress tensor obtained by inverting focal mechanisms of the largest events reveals a ne trending extension and the majority of the aftershocks are kinematically consistent deviations from the dominant extensional strain pattern are observed for those earthquakes activating minor structures

solution cleavage and its relationship to major structures in the idaho utah wyoming thrust belt micrites of the jurassic twin creek formation in the idaho utah wyoming thrust belt show spaced cleavage developed during folding and thrusting cleavage in each thrust sheet forms mainly by pressure solution aided by elevated temperatures and pressures caused by increased overburden as a result of emplacement of earlier overriding thrust sheets within each thrust sheet cleavage develops early and is contemporaneous with microscopic to mesoscopic buckle folds and faults large scale ramp folds formed during major motion on the thrust postdate the cleavage and passively rotate it into major fans

field aligned neutral wind bias correction scheme for global ionospheric modeling at midlatitudes by assimilating formosat 3 cosmic hmf2 data under geomagnetically quiet conditions this study demonstrates the usage of a data assimilation procedure which ingests the formosat 3 cosmic f3 c hmf2 observations to correct the model wind biases to enhance the capability of the new global ionosphere plasmasphere electrodynamics ipe model under geomagnetically quiet conditions the ipe model is built upon the field line interhemispheric plasma model with a realistic geomagnetic field model and empirical model drivers the hmf2 observed by the f3 c radio occultation technique is utilized to adjust global thermospheric field aligned neutral winds i e a component of the thermospheric neutral wind parallel to the magnetic field at midlatitudes according to a linear relationship between time differentials of the field aligned wind and hmf2 the adjusted winds are further applied to drive the ipe model the comparison of the modeled electron density with the observations of f3 c and ground based gps receivers at the 2012 march equinox suggests that the modeled electron density can be significantly improved in the midlatitude regions of the southern hemisphere if the wind correction scheme is applied moreover the f3 c observation the ipe model and the wind bias correction scheme are applied to study the 2012 southern hemisphere midlatitude summer nighttime anomaly southern msna weddell sea anomaly wsa event at december solstice for examining the role of the neutral winds in controlling the longitudinal variation of the southern msna wsa behavior with the help of the wind bias correction scheme the ipe model better tracks the f3 c observed eastward movement of the southern msna wsa feature the apparent eastward movement of the southern msna wsa features in the local time coordinate is primarily caused by the longitudinal variation in the declination angle of the geomagnetic field that controls the field aligned projection of both geographic meridional and zonal components of the neutral wind both the ipe simulations and the f3 c observations show the significant longitudinal variation in the speed of the eastward movement of the southern msna wsa

longitudinal variation in global navigation satellite systems tec and topside ion density over south american sector associated with the four peaked wave structures 1 recent observations of the low latitude ionospheric electron density revealed a four peaked longitudinal structure in the equatorial ionization anomaly when plotted at a constant local time frame it was proposed that neutral wind driven e region dynamo electric fields due to nonmigrating tidal modes are responsible for this pattern we examine the four peaked structure in the observed topside ion density and its manifestation as longitudinal structures in total electron content tec over south america the strong longitudinal variation in tec characterized by larger value over brazilian eastern longitude sector as compared to that over the peruvian western longitude is modeled using the sheffield university plasmasphere ionosphere model supim aiming to identify the control factors responsible for the longitude variation we found that the supim runs using as input the existing standard models of vertical drift and thermospheric winds do not explain the tec longitudinal structure realistic values of these control parameters were generated based on the strong vertical drift longitudinal variation as determined from magnetometer and digisonde data and appropriately adjusted winds horizontal wind model these realistic vertical drifts together with the modified thermospheric wind when used as input to the supim are found to satisfactorily explain the longitudinal differences in the tec and topside ion density ni over south america the study shows that the tec in the whole latitude distribution is larger over the east coast than over the west coast of south america and that the vertical drift and thermospheirc winds control the longitudinal four wave structure in the tec and ni

structure of the lithosphere beneath the eastern alps southern sector of the transalp transect abstract the interpretation of the seismic vibroseis and explosive transalp profiles has examined the upper crustal structures according to the near surface geological evidences and reconstructions which were extrapolated to depth only the southern sector of the transalp transect has been discussed in details but its relationship with the whole explored chain has been considered as well the seismic images indicate that pre collision and deep collision structures of the alps are not easily recognizable conversely good records of the neo alpine to present architecture were provided by the seismic sections two general interpretation models crocodile and extrusion have been sketched by the transalp working group 2002 both illustrate the continental collision producing strong mechanical interaction of the facing european and african margins as documented by giant lithosphere wedging processes arguments consistent with the extrusion model and with the indentation of adriatic southalpine lithosphere underneath the tauern window tw are according to the previous dss reconstructions the bouguer anomalies and the receiver functions seismological data the european moho descends regularly attaining a zone south of the periadriatic lineament pl the moho boundary and its geometry appear to be rather convincing from images of the seismic profile the tauern window intense uplift and exhumation is coherent with the strong compression regime which acted at depth thus originating the upward and lateral displacement of the mobile and ductile penninic masses according to the extrusion model the indentation of the penninic mobile masses within the colder and more rigid adriatic crust cannot be easily sustained wedging of the adriatic stiffened lower crust under high stresses and into the weaker penninic domain can be a more suitable hypothesis furthermore the intrusion of the european penninic crustal wedge underneath the dolomites upper crust is not supported by any significant uplifting of the dolomites the total average uplift of the dolomites during the neogene appears to be 6 7 times smaller than that recognized in the tw markedly the northward dip of the pl reaching a depth of approximately 20 km is proposed in our interpretation finally the adriatic upper crustal evolution points to the late post collision change in the tectonic grow up of the eastern alps orogenic chain the tectonic accretion of the northern frontal zone of the eastern and central alps was interrupted from the late miocene serravallian tortonian onward as documented by the molasse basin evolution on the contrary the structural nucleation along the s vergent tectonic belt of the eastern southern alps montello friuli thrust belt severely continued during the messinian and the plio pleistocene this structural evolution can be considered to be consistent with the deep under thrusting and wedge indentation of the adriatic lithosphere underneath the southern side of the eastern alps thrust and fold belt similarly the significance of the magmatic activity for the construction of the southern alps crust and for its mechanical and geological differentiation which qualified the evolution of the thrust and fold belt is highlighted starting with the permian triassic magmatism and progressing with the paleogene occurrences along the periadriatic lineament and in the venetian magmatic province lessini euganei hills

late oligocene neogene evolution of europe adria collision new structural and geochronological evidence from the giudicarie fault system italian eastern alps the giudicarie fault system giudicarie sensu stricto meran mauls passeier thurnstein and jaufen faults represents a sharp break in the generally e w strike direction of the orogen scale periadriatic fault system and is a key element for understanding the late oligocene neogene evolution of the alpine chain the kinematics timing and magnitude of movements on the giudicarie fault system are presented here on the basis of a detailed structural study of the component fault segments combined with zircon and apatite fission track analysis from closely spaced samples two main tectonic phases are established 1 back thrusting of the austroalpine units over the southern alps around 32 ma recorded by basement and limestone mylonites along the giudicarie and meran mauls faults with transport directions toward 100 110 and 2 later sinistral transpressive displacement characterized by structures at the ductile brittle transition which overprinted the top to e ese thrust related mylonites but also partitioned into a major system of transcurrent faults in the southalpine domain it was during this later event that the periadriatic fault attained its present day geometry however the amount of sinistral displacement along the giudicarie system was only 15 20 km the magnitude is established here from the 15 km sinistral offset of the jaufen mylonites across the passeier brittle fault and the 20 km long gap in the otherwise continuous distribution of oligocene tonalitic lamellae along the giudicarie fault a direct structural connection is also established between the brenner and the jaufen faults this constrains the timing of the second phase since it must postdate the main exhumation phase of the tauern window at 20 18 ma the results of this study argue against an originally straight periadriatic fault the giudicarie fault formed a restraining bend in this part of the periadriatic fault system since at least the late miocene and probably since the late oligocene

structural evolution of a foreland fold and thrust belt the umbria marche apennines italy abstract outcrop scale structures that record a progressive sequence of deformation can be used to clarify the kinematic evolution of an entire fold and thrust belt the temporal progression of the compressional deformation as reconstructed by means of a mesoscopic structural analysis provides a key for unraveling the kinematic history of the umbria marche apennines central italy overprinting relationships at outcrop scale allow for the recognition of three distinct structural stages which are in sequence a layer parallel shortening b folding c thrusting individual stages are explained in the framework of a progressive deformation model where shortening of the sedimentary cover was continuous and occurred during a single contractional episode as a consequence of tip line folding processes a comparison of this history with those reported from other fold and thrust belts shows that layer parallel shortening folding and thrusting are sequentially dominant processes in areas which have experienced compressional deformation

from rifting to drifting tectonic evolution of the south alpine upper crust from the triassic to the early cretaceous abstract the tectonic evolution of the south alpine rifted margin is discussed on the base of four palinspastic upper crustal profiles extension related to the movements between adria and europe began in the norian after variscan orogeny late carboniferous to middle permian orogenic collapse and continental scale wrenching from the late triassic to the early liassic stretching was mostly limited to the lombardian basin during this time extension was mainly controlled by four major listric faults symmetrically centred around the late carboniferous early permian collio grabens smaller faults which also started in the norian were progressively de activated during the late triassic after the middle liassic faulting in the lombardian basin gradually ceased and the site of extension shifted westwards i e towards the future site of crustal separation extension was then controlled by a set of west dipping normal faults oceanic crust was formed not later than 157 ma the overall extension along the profile which had a final length of 290 km was 52 km which corresponds to a stretching factor of 1 22 for the whole length of the preserved margin the strain rate is ca 1 10 16 s the sedimentation history suggests that the extension of the south alpine margin was a continuous process from the norian to the middle jurassic the changes in tectonic pattern are related to progressive hardening of the lithospheric segment undergoing slow extension

global ionospheric response to nonmigrating de3 and de2 tides forced from below 1 in this paper we present the global spatial structure and seasonal variability of the cosmic electron density response to the forced from below de3 and de2 tides during the period january 2008 to march 2009 the cosmic electron density at fixed altitudes and saber temperatures were utilized in order to define the ionospheric de3 and de2 tidal response to the de3 and de2 temperature tides coming from below the tidal waves from both data sets have been extracted by the same data analysis method the latitude structure of the ionospheric response for heights up to 450 500 km is distributed on both sides of the dip equator at about 30 modified dip latitude above 500 km the response is approximately confined over the equator two altitude regions of enhanced ionospheric response are found an upper level response above 300 km and a bottom level one below 250 km the two regions are separated by a narrow altitude zone with no tidal response the different phase structure of the ionospheric response in both altitude regions suggests that 1 the upper level response is mainly due to the de3 de2 modulated vertical plasma drift and 2 the bottom level response is complex and in all likelihood is caused by more than one mechanism

pressure solution seams in carbonatic fault rocks mineralogy micro nanostructures and deformation mechanism we have investigated mineralogy and micro nanostructures of pressure solution seams in four different carbonatic faults with kilometric displacement cropping out in the northern apennines italy disregarding the different protoliths and deformation conditions the stylolite filling material has almost constant mineralogical characteristics being invariably formed by an ultrafine matrix that encloses relic insoluble grains among which quartz feldspars and detritic micas the ultrafine matrix also hosts syn and post dynamic phases e g foliation parallel goethite flakes and apatite euhedral nanocrystals in random orientation the ultrafine matrix is formed by smectitic clays in nanosized 001 lamellae showing pervasive interlayer fissuring layer bending and preferred orientation parallel to the slipping surface stylolite mineralogy and micro nanostructures may affect deformation mechanisms and permeability properties of the fault rock in particular we propose that the extremely low friction coefficient of smectite would favour frictional sliding along the faults and that the fissured and oriented nanostructure of the smectite dominated seams would enhance the sealing attitude of the structures in the fault perpendicular direction

hydrothermal breccias in vein type ore deposits a review of mechanisms morphology and size distribution abstract breccias are among the most widely distributed rock textures found in hydrothermal vein type deposits previous studies have mainly been interested in developing qualitative descriptive approaches leading to a confusing profusion of terms brecciation originates in numerous ways resulting in highly complex classification systems and frequent misinterpretations of facies field observations are difficult to reconcile with physical theories of fragmentation partly due to the fact that few satisfactory quantitative tools have been developed a review of the main brecciation processes occurring in hydrothermal vein type deposits allows for the discrimination between chemical and physical mechanisms including tectonic comminution wear abrasion two types of fluid assisted brecciation hydraulic and critical volume expansion or reduction impact and collapse each of these mechanisms can be distinguished using nonscalar parameters that describe breccia geometry including fragment morphology size distribution of the fragments fabric and dilation ratio the first two parameters are especially important because 1 the morphology of the fragments allows chemical and physical mechanical breccias to be distinguished and 2 the particle size distribution psd is a function of the energy input during breccia formation the slope of the cumulative psd fractal dimension ranges from high values for high energy brecciation processes to low values for low energy processes indicated by an isometric distribution the evolution of a vein system can be divided into three stages propagation wear and dilation these stages are separated by one threshold of mechanical discontinuity and one of hydraulic continuity these two thresholds also mark the transition between different types of brecciation mineralization occurs during all three stages and may display different textures due to pressure variations the use of quantitative parameters in fault related hydrothermal breccias allows a better understanding of the physical parameters related to a vein environment including structural setting and crustal level as well as fluid rock interactions recognition of the different breccia types could also be important during the early stages of mineral exploration

magma sources and petrogenesis of the early middle paleozoic backarc granitoids from the central part of the qilian block nw china abstract the petrology geochemistry geochronology and sr nd hf isotopes of the backarc granitoids from the central part of the qilian block are studied in the present work both s and i type granitoids are present in petrographic classification they are granite alkali feldspar granite felsic granite diorite quartz diorite granodiorite and albite syenite the shrimp ages are 402 447 ma for the s type and 419 451 ma for the i type granitoids they are mostly high k calc alkaline granitoids the s type granitoids are weakly to strongly peraluminous and are characterized by negative eu anomalies eu eu 0 18 0 79 the i type granitoids are metaluminous to weakly peraluminous and are characterized mostly by small negative to small positive eu anomalies eu eu 0 71 1 16 the initial 87 sr 86 sr values are 0 708848 0 713651 for the s type and 0 704230 0 718108 for the i type granitoids the e nd 450 ma values are 8 9 4 1 and 9 7 1 9 for the s type and i type granitoids respectively the t dm values are 1 5 2 4 ga for the s type and 1 0 2 3 ga for the i type granitoids for the qilian block the backarc granitoid magmatism took place approximately 60 million years after the onset of the southward subduction of the north qilian oceanic lithosphere and lasted approximately 50 million years partial melting of the source rocks consisting of the neoproterozoic metasedimentary rocks of the huangyuan group and the intruding lower paleozoic basaltic rocks could produce the s type granitoid magmas partial melting of basaltic rocks mixed with lower continental crustal materials could produce the i type granitoid magmas major crustal growth occurred in the late archean and meso paleoproterozoic time for the qilian block the magma generation was primarily remelting of the crustal rocks with only little addition of the mantle materials after 1 0 ga for the qilian block

longitudinal variation of f region electron density and thermospheric zonal wind caused by atmospheric tides 1 simultaneous observations of the electron density and the zonal wind obtained by the champ satellite at 400 km are used to study systematic longitudinal variations the time period selected is august september 2004 allowing observations at pre noon and post sunset hours the equatorial ionization anomaly eia and the zonal delta wind deviation from zonal average show a persistent and dominant 4 peaked longitudinal variation we interpret this structure as caused by the wavenumber 3 nonmigrating diurnal tide de3 the eia and the zonal delta wind exhibit extrema at about the same longitudes but while the intensifications of the eia and the delta wind are in phase during the evening hours they are out of phase in the morning possible coupling mechanisms are investigated

fault architecture and deformation mechanisms in exhumed analogues of seismogenic carbonate bearing thrusts abstract faults in carbonates are well known sources of upper crustal seismicity throughout the world in the outer sector of the northern apennines ancient carbonate bearing thrusts are exposed at the surface and represent analogues of structures generating seismicity at depth we describe the geometry internal structure and deformation mechanisms of three large displacement thrusts from the km scale to the microscale fault architecture and deformation mechanisms are all influenced by the lithology of faulted rocks where thrusts cut across bedded or marly limestones fault zones are thick tens of metres and display foliated rocks s cc tectonites and or ypr cataclasites characterized by intense pressure solution deformation in massive limestones faulting occurs in localized narrow zones that exhibit abundant brittle deformation a general model for a heterogeneous carbonate bearing thrust is proposed and discussed fault structure affected by stratigraphic heterogeneity and inherited structures influences the location of geometrical asperities and fault strain rates the presence of clay minerals and the strain rate experienced by fault rocks modulate the shifting from cataclasis dominated towards pressure solution dominated deformation resulting structural heterogeneity of these faults may mirror their mechanical and seismic behaviour we suggest that seismic asperities are located at the boundaries of massive limestones in narrow zones of localized slip whereas weak shear zones constitute slowly slipping portions of the fault reflecting other types of aseismic behaviour

interaction of cataclasis and pressure solution in a low temperature carbonate shear zone the mineralogical and elemental variations across the main shear zone of the saltville thrust at sharp gap in knoxville tennessee u s a were studied in a suite of deformed and undefromed carbonate rock samples using x ray diffraction and electron microprobe methods an examination of the samples for deformation effects at mesoscopic scale and under the optical microscope reveals familiar cataclastic deformation features including foliated cataclasites and microbreccias occurring in a well defined 1 2 m wide zone of intense deformation plus evidence of hydrofracturing and extensive syndeformational pressure solution there exists a clear correlation between the observed cataclastic deformation and mineral and elemental distribution which we interpret to result from a deformation induced dolomite to calcite transformation in the shear zone the transformation has resulted in removal of mg from the shear zone selective deposition of calcite as an intergranular cement in cataclasite microbreccia units and a relative increase in the concentration of detrital quartz and feldspars the compositional difference between the shear zone and wall rocks is explained in connection with cataclastic deformation features in terms of a model in which a dual pressure solution cataclastic flow mechanism leads to a gradual cementation hardening of segments of the shear zone instabilities could occur via permeability reduction and increased pore pressure within these segments hydrofracturing of the hardened segments along with high strain rate reordering of the shear zone materials reset the ruptured zone back to the dual deformation mechanism regime as a long term effect the compositional transformation of the shear zone is expected to prolong periods of creep and cause smaller coseismic stress drops since under the imposed conditions calcite is more ductile and soluble than dolomite

from velocity and attenuation tomography to rock physical modeling inferences on fluid driven earthquake processes at the irpinia fault system in southern italy we retrieve 3 d attenuation images of the crustal volume embedding the fault system associated with the destructive ms 6 9 1980 irpinia earthquake by tomographic inversion of t measurements a high qp anomaly is found to be correlated with the 1980 fault geometry while the qs model shows regional scale variations related to the ne edge of the uplifted pre tertiary limestone an upscaling strategy is used to infer rock properties such as porosity consolidation type of fluid mixing and relative saturation percentage at 8 10 km fault depth we constrain the porosity and consolidation in the ranges 4 5 and 5 9 respectively with the possible fluid mixes being both brine co2 and ch4 co2 the consolidation parameter range indicates high pore pressures at the same depths these results support the evidence for a fracture system highly saturated in gases and a seismicity triggering mechanism at the fault zone which is strongly controlled by fluid induced pore pressure changes

global response of the ionosphere to atmospheric tides forced from below comparison between cosmic measurements and simulations by atmosphere ionosphere coupled model gaia 1 this paper for the first time presents a detailed comparison between simulated and observed global electron density responses to different atmospheric tides forced from below the recently developed earth s whole atmospheric model from the troposphere to the ionosphere called gaia has been used for the simulation of the electron density tidal responses they have been compared with the extracted from the cosmic electron density data tidal responses for the period of time october 2007 to march 2009 particular attention has been paid to the nonmigrating de3 de2 and migrating dw1 sw2 and tw3 electron density responses the gaia model reproduced quite well the cosmic de3 de2 responses both simulations and observations revealed three altitude regions of enhanced electron density responses 1 an upper level response above 300 km height apparently shaped mainly by the fountain effect 2 a response located near altitudes of 200 270 km and 3 a lower thermospheric response situated near 120 150 km height a possible mechanism is suggested for explaining the two lower level responses for the first time the gaia model simulations supported the observational evidence found in the cosmic measurements that the ionospheric wn4 wn3 longitude structure is not generated only by the de3 de2 tide as it has been often assumed as regards the comparison of the migrating dw1 sw2 and tw3 responses the obtained results clearly demonstrate that the gaia model reproduce very well of the sw2 and tw3 cosmic electron density responses the only main discrepancy is seen in the migrating dw1 response the observation does not support the splitting of the simulated response at both sides of the equator this is due mainly to the difference between the saber and gaia sw2 tide in the lower thermosphere as it turned out that the dw1 electron density response strongly depends on the mean features of the lower thermospheric sw2 tide

static versus dynamic fracturing in shallow carbonate fault zones moderate to large earthquakes often nucleate within and propagate through carbonates in the shallow crust the occurrence of thick belts of low strain fault related breccias is relatively common within carbonate damage zones and was generally interpreted in relation to the quasi static growth of faults here we report the occurrence of hundreds of meters thick belts of intensely fragmented dolostones along a major transpressive fault zone in the italian southern alps these fault rocks have been shattered in situ with negligible shear strain accumulation the conditions of in situ shattering were investigated by deforming the host dolostones in uniaxial compression both under quasi static strain rate 10 5s 1 and dynamic strain rate 50s 1 loading dolostones deformed up to failure under low strain rate were affected by single to multiple discrete extensional fractures sub parallel to the loading direction dolostones deformed under high strain rate were shattered above a strain rate threshold of 120s 1 and peak stresses on average larger than the uniaxial compressive strength of the rock whereas they were split in few fragments or remained macroscopically intact at lower strain rates fracture networks were investigated in three dimensions showing that low and high strain rate damage patterns fracture intensity aperture orientation were significantly different with the latter being similar to that of natural in situ shattered dolostones i e comparable fragment size distributions in situ shattered dolostones were thus interpreted as the result of high energy dynamic fragmentation dissipated strain energies 1 8 mj m3 similarly to pulverized rocks in crystalline lithologies given their seismic origin the presence of in situ shattered dolostones can be used in earthquake hazard studies as evidence of the propagation of seismic ruptures at shallow depths

contrasting fluid events giving rise to apparently similar diagenetic products late stage dolomite cements from the southern alps and central apennines italy

structure and origins of the weddell sea anomaly from tidal and planetary wave signatures in formosat 3 cosmic observations and gaia gcm simulations the weddell sea anomaly wsa is a recurrent feature of the austral summer midlatitude ionosphere where electron densities are observed to maximize during the local nighttime in this study tidal decomposition is applied to formosat 3 formosa satellite constellation observing system for meteorology ionosphere and climate cosmic total electron content tec and electron density observations between 2007 and 2012 to quantify the components dominating local time and spatial variation in the wsa region our results present some of the first three dimensional spaceborne analyses of the wsa from a tidal perspective over multiple years we find that the features of the wsa can be reconstructed as the result of superposition between the dominant diurnal standing d0 eastward wave number 1 de1 westward wave number 2 dw2 and stationary planetary wave 1 spw1 components in tecs producing the characteristic midnight wsa peak the d0 de1 dw2 and spw1 components are found to be an interannually recurring feature of the southern midlatitude to high latitude ionosphere during the summer manifesting as enhancements in electron density around 300 km altitude of the summer middle to high magnetic latitudes the phases of the aforementioned nonmigrating diurnal signatures in electron density in this region are near evanescent suggesting in situ generation rather than upward propagation from below however the spw1 signature shows some signs of an eastward tilt with altitude suggesting possible downward propagation the relation of these components to possible generation via in situ photoionization or plasma transport along magnetic field lines is also discussed using results from the ground to topside model of atmosphere and ionosphere for aeronomy gaia general circulation model gcm connecting the tidal interpretation of the wsa to previously examined generation mechanisms

simulated equinoctial asymmetry of the ionospheric vertical plasma drifts 1 this paper studies the influence of the lower thermospheric tidal winds below 105 km on the equinoctial asymmetry of the equatorial vertical e b plasma drifts v using theoretical ionospheric dynamo model ii of the institute of geology and geophysics chinese academy of sciences tidm iggcas ii and tidal winds below 105 km from thermosphere ionosphere mesosphere energetics dynamics satellite doppler interferometer tidi observations although a series of other nonmigrating tides also affect the v asymmetry the simulated equinoctial asymmetry in v are mainly driven by the migrating diurnal tide dw1 migrating semidiurnal tide sw2 de3 and dw2 nonmigrating tides the asymmetry in daytime v varies with local time and longitude and mainly shows three features first the simulated daytime v during the march equinox is larger than that during the september equinox in most of longitudinal sectors this asymmetry is mainly driven by the semiannual oscillation sao of the migrating diurnal tide in the tropical mesosphere lower thermosphere mlt region and the equinoctial asymmetry of the migrating semidiurnal tide also plays an important role in the generation of this asymmetry second the daytime v asymmetry in the eastern hemisphere is more significant than that in the western hemisphere our simulation suggests that the longitudinal variations of the geomagnetic fields and dw2 tides play important roles in the generation of this hemisphere difference third there is an obvious wave number 4 longitudinal structure in the v asymmetry our simulation suggests that this wave number 4 structure is mainly driven by the equinoctial asymmetry of the de3 tide

mineral solubility and aqueous speciation under hydrothermal conditions to 300 c the carbonate system as an example carbon is a major element in the earth s system and plays an important role in many geochemical processes including metamorphism volcanism oceanic systems and atmospheric evolution knowledge and understanding of chemical speciation mineral solubility and reactivity involving carbon are very important in order to qualitatively and quantitatively understand these processes indeed dissolved inorganic carbon is among the major components of natural geothermal fluids it originates from various sources including magmatic degassing rock dissolution and organic matter degradation e g giggenbach 1992 giggenbach et al 1993 simmons and cristenson 1994 sanoa and marty 1995 dissolved co2 is the most common form of dissolved inorganic carbon in these systems though other forms exist like ch4 and co but usually in much lower concentrations than co2 e g chiodini and marini 1998 stefansson and arnorsson 2002 the concentrations of dissolved inorganic carbon dic in geothermal fluids from active geothermal systems throughout the world are shown in figure 1a together with the ph of the fluids in general the dic concentration increases in geothermal fluids with increasing temperature from a few mmol per kg up to half a mole per kg of fluid this increase is accompanied by a decrease in the fluid ph fig 1b higher concentrations not shown are observed in fumarole fluids discharging volcanic gases e g chiodini et al 1996 at earth s surface co2 also degasses through the soils in active geothermal systems e g chiodini et al 1998 the chemistry and transport of dic in natural geothermal systems is influenced by many processes including magma degassing water rock interaction and partitioning of co2 between liquid and vapor phases upon boiling and phase separation it has been concluded that the concentration of dic and all other major elements besides incompatible elements such as cl are

longitudinal structure of the equatorial anomaly in the nighttime ionosphere observed by image fuv 1 the far ultraviolet imager fuv on board the image satellite provides an instantaneous global view of the oi 135 6 nm nightglow with 2 min time resolution because the oi 135 6 nm emission from the nighttime ionosphere is determined by the line of sight integrated plasma density the nightglow images are useful for studying the nighttime low latitude ionosphere globally with the image fuv 135 6 nm observations from march to june 2002 we have examined the global characteristics of the nighttime equatorial anomaly ea by constructing a constant local time map lt map in which pixels within an assigned local time range are extracted from the image fuv nightglow images obtained over an observation period of 3 days or more and are put together to compose a global distribution map of emission intensities at that local time these lt maps show that the development of the ea has a significant longitudinal structure in which peaks and dips of the crest emission intensity and the crest latitude have about 90 longitudinal separation in the longitude range from 0 to 250 although there is not enough data over the american sector this result suggests that the ea longitudinal structure has a prominent zonal component of the wave number 4 the observed longitudinal structure of the nighttime ea could not be fully explained by factors such as the empirical electric field and neutral wind models the geomagnetic declination angle or the displacement of the geomagnetic equator from the geographic equator to explain the observed longitudinal structure of the ea in particular the wave number 4 feature we may need to consider other forcing for example nonmigrating tide originated from the lower atmosphere

hydrothermal dolomitization in platform and basin carbonate successions during thrusting a hydrocarbon reservoir analogue mesozoic of venetian southern alps italy abstract the early jurassic dolomitized carbonates in the venetian alp represent a surface analogue of the hydrocarbon exploration targets in adriatic offshore and po plain italy dolomitization affected the carbonate platform of monte zugna formation lower jurassic and the neptunian dikes breccia in the pelagic maiolica formation uppermost jurassic lower cretaceous improving the poro perm characteristics petrography stable isotope strontium isotope ratio trace element and fluid inclusion analyses were carried out on samples from the monte grappa anticline which is the direct analogue for subsurface the petrographic analyses showed a first pervasive replacement dolomitization phase d1 followed by volumetrically less important dolomite cement precipitation phases d2 d3 ds the same quite wide range of oxygen isotope 9 to 2 v pdb is observed in all dolomite types the 13 c range is in the positive field of marine derived carbonate from 0 5 to 3 2 pdb the trace element analysis showed a slight enrichment in fe and mn contents in the monte zugna dolostones with respect the original limestone the same dolomite precipitation temperature up to 105 c th was observed in the replacement and cement dolomites suggesting a unique dolomitization event this temperature largely higher than the maximum burial temperature about 50 c supports a hydrothermal origin of the dolomitizing fluids which had a seawater to brackish composition the data collected suggest a hydrothermal dolomitization occurring during to the south alpine thrusting according to the squeegee model the interpretation is consistent with the dolomitization model proposed for similar jurassic successions in the central southern alps this study indicates that the deformed foreland and thrust fold belts carbonates in po plain and adriatic offshore are suitable to be dolomitized and therefore reflect an efficient hydrocarbon exploration play

large scale thin skinned thrusting in the southern alps kinematic models the tectonics of the southern alps are dominated by thrusting on extensive ramp flat systems and by folding some of which is ramp folding basement slivers are involved that frontally are not thicker than 5 km the most unequivocal section is that of the grigna mountains east of lake como for which kinematic modeling based on material balance considerations results in a shortening of 40 km it is separated from the grona section in the west and the valtorta section in the east by probably pre existing transverse zones that cut through the important decollement horizons and define blocks of different depths to basement local tectonics across these transverse zones change abruptly while over all shortening remains constant in particular both east and west of the grigna section basement ramp folds were wedged into the very incompetent raibl beds provoking back thrusting of the thick hauptdolomit and higher sediments with the substitution of the original cover of the frontal limb of the basement fold this new kinematic interpretation is compatible with the information facilitates the construction of balanced sections and is required for lateral constancy of shortening

soil gas distribution in the main coseismic surface rupture zone of the 1980 ms 6 9 irpinia earthquake southern italy soil gas measurements of different gas species with different geochemical behaviors were performed in the area of the pecore plain a 200 m 300 m sized fault bounded extensional basin located in the northern mount marzano massif in the axial belt of the southern apennine chain the pecore plain area was affected by coseismic surface faulting during the ms 6 9 1980 irpinia earthquake the strongest and most destructive seismic event of the last 30 years in southern italy the collected data and their geostatistical analysis provide new insights into the control exerted by active fault segments on deep seated gas migration toward the surface the results define anomalies that are aligned with the nw se trending coseismic rupture of the 1980 earthquake along the western border of the plain as well as along the southern border of the plain where a hidden e w striking fault is inferred geospatial analysis highlights an anisotropic spatial behavior of 222rn along the main nw se trend and of co2 along the e w trend this feature suggests a correlation between the shape and orientation of the anomalies and the barrier conduit behavior of fault zones in the area furthermore our results show that gas migration through brittle deformation zones occurs by advective processes as suggested by the relatively high migration rate needed to obtain anomalies of short lived 222rn in the soil pores

fluid flow reconstruction in karstified panormide platform limestones north central sicily implications for hydrocarbon prospectivity in the sicilian fold and thrust belt diagenetic analysis based on field and petrographic observations isotope and microthermometric data was used to reconstruct the fluid flow history of the cretaceous shallow water limestones from the panormide platform exposed in north central sicily analysis focused on diagenetic products in cavities and dissolution enlarged fractures of the karstified limestones that occur just below a regional unconformity the fluid flow history could be broken down into five stages that were linked to the kinematic and burial history of the region 1 petrography zoned cathodoluminescence and speleothem textures and stable isotopes 6 5 18ov pdb 3 5 and 0 13cv pdb 14 indicate that the earliest calcite phase was associated with karstification during emergence of the platform limestone dissolution at this stage is important with regard to possible reservoir creation in the panormide palaeogeographic domain 2 fine grained micrite sedimentation dated as latest cretaceous by nannopalaeontology and its 87sr 86sr isotope ratio 0 7078 marks replacement by marine fluids during subsequent submergence of the karstified platform 3 the following calcite cement was still precipitated by marine derived fluids 7 0 18ov pdb 5 0 and 3 0 13cv pdb 0 5 tm 2 to 5 c but at increasingly higher temperatures th 60 120 c this has been interpreted as precipitation during oligocene foredeep burial 4 hot th 130 180 c low saline tm 2 5 c fluids with increasingly higher calculated 18osmow signatures 6 to 14 subsequently invaded the karst system these fluids most likely migrated during fold and thrust belt development the low salinity and relatively high 18osmow signatures of the fluids are interpreted to be the result of clay dewatering reactions the presence of bitumen and associated fluorite with hydrocarbon inclusions at this stage in the paragenesis constrains the timing of oil migration in the region 5 finally high saline fluids with elevated 87sr 86sr 0 7095 0 7105 signatures invaded the karst system this last fluid flow event was possibly coeval with localized dolomitization and calcite cementation along high angle faults of pliocene age as suggested by identical radiogenic signatures of these diagenetic products

structural and temporal evolution of a reactivated brittle ductile fault part i fault architecture strain localization mechanisms and deformation history abstract faults are by nature dynamic as their architecture and composition evolve progressively in space and through time steered by the interplay between strain weakening and hardening mechanisms this study combines structural analysis geochemistry and chlorite geothermometry to investigate deformation and strain localization mechanisms of the kvenklubben fault a paleozoic brittle ductile thrust in northern norway with the goal to constrain their temporal variations and the consequences thereof on fault architecture development and rheological behavior the fault evolved from an initially discrete brittle feature slipping mainly by seismogenic ruptures to a wide brittle ductile phyllonite deforming by aseismic creep the formation of mechanically weak phyllosilicates by decarbonation of footwall dolostones and carbonation of hanging wall metabasalts was the main weakening mechanism whereas partitioning of fluid flow and fracture sealing following transient high pore pressure driven embrittlement caused episodic and localized strain hardening the interplay between strain weakening and hardening mechanisms caused the fault core to widen we suggest that the ability for carbonate hosted faults to slip by seismogenic rupture is also a function of the faults structural evolutionary stage and that it decreases progressively with fault maturity this study demonstrates the importance of calibrating the present day fault anatomy against the dynamic character of faults which evolve geometrically compositionally and mechanically in space and through time

an empirical model of the occurrence of an additional layer in the ionosphere from the occultation technique preliminary results about 8 year electron density profile edp data from the cosmic formosat 3 satellites radio occultation technique were used to investigate the additional stratification of the f2 the so called f3 layer layer over the equatorial and low latitude ionosphere on a global scale for both the bottomside and topside ionosphere the f3 layer was recognized through the altitude differential profile featured by two maxima existing from the selected edp profile there were 37 000 bottomside and 25 000 topside cases of f3 layer selected out of 1 27 million occultation events at equatorial and low latitude areas during the period of april 2006 to august 2014 the statistical results for the bottomside ionosphere resemble that reported in zhao et al 2011a while in the topside the highest occurrence of f3 layer shows a 3 4 h delay depending on the altitude range of the stratification the magnetic latitude distribution shows different dependence with a tendency to form a single crest toward high altitude also the seasonal variation is weaker in the topside ionosphere compared to the bottomside one especially in the high altitude then we build up an empirical model of the f3 layer occurrence using the bottomside statistics based on empirical orthogonal function eof decomposition as it gets the inherent characters inside the data set and converges quickly the model well grasps the main features of the f3 occurrence e g the f3 occurrence s sensitivity on the magnetic latitude further in order to accommodate the ground observation a corrected factor was introduced as f3 layer is an important phenomenon in the low latitude ionosphere we have made an attempt to describe its feature with a consecutive function although future work needs to be done for an overall expression of this structure

fault deformation mechanisms and fault rocks in micritic limestones examples from corinth rift normal faults abstract a multidisciplinary study investigates the influence of different parameters on fault rock architecture development along normal faults affecting non porous carbonates of the corinth rift southern margin here some fault systems cut the same carbonate unit pindus and the gradual and fast uplift since the initiation of the rift led to the exhumation of deep parts of the older faults this exceptional context allows superficial active fault zones and old exhumed fault zones to be compared our approach includes field studies micro structural optical microscope and cathodoluminescence geochemical analyses 13 c 18 o trace elements and fluid inclusions microthermometry of calcite sin kinematic cements our main results in a depth window ranging from 0 m to about 2500 m are i all cements precipitated from meteoric fluids in a close or open circulation system depending on depth ii depth in terms of p t condition determines the development of some structures and their sealing iii lithology marly levels influences the type of structures and its cohesive non cohesive nature iv early distributed rather than final total displacement along the main fault plane is the responsible for the fault zone architecture v petrophysical properties of each fault zone depend on the variable combination of these factors

location of largest earthquake slip and fast rupture controlled by along strike change in fault structural maturity due to fault growth earthquake slip distributions are asymmetric along strike but the reasons for the asymmetry are unknown we address this question by establishing empirical relations between earthquake slip profiles and fault properties we analyze the slip distributions of 27 large continental earthquakes in the context of available information on their causative faults in particular on the directions of their long term lengthening we find that the largest slips during each earthquake systematically occurred on that half of the ruptured fault sections most distant from the long term fault propagating tips i e on the most mature half of the broken fault sections meanwhile slip decreased linearly over most of the rupture length in the direction of long term fault propagation i e of decreasing structural maturity along strike we suggest that this earthquake slip asymmetry is governed by along strike changes in fault properties including fault zone compliance and fault strength induced by the evolution of off fault damage fault segmentation and fault planarity with increasing structural maturity we also find higher rupture speeds in more mature rupture sections consistent with predicted effects of low velocity damage zones on rupture dynamics since the direction s of long term fault propagation can be determined from geological evidence it might be possible to anticipate in which direction earthquake slip once nucleated may increase accelerate and possibly lead to a large earthquake our results could thus contribute to earthquake hazard assessment and earthquake early warning

strong evidence for the tidal control on the longitudinal structure of the ionospheric f region this paper presents for the first time the global latitude structure and seasonal variability of the ionospheric response to the forced from below de3 and de2 tides during the period of time january 2008 march 2009 the cosmic hmf2 and saber temperature data have been utilized in order to define the ionospheric de3 and de2 tidal response to the de3 and de2 temperature tides propagating from below the cosmic de3 and de2 hmf2 tidal oscillations are derived by the same method as the tides seen the saber temperatures it has been shown that the longitude wave 4 and wave 3 hmf2 structures observed respectively in september and may 2008 are forced mainly by de3 wave 4 and de2 wave 3 temperature tides coming from below the longitude wave 3 hmf2 structure observed in january 2008 however is forced by the combined action of the de2 temperature tide coming from below and the spw3 probably generated in situ

dolomite characteristics and diagenetic model of the calcari grigi group asiago plateau southern alps italy an example of multiphase dolomitization a multidisciplinary study conducted over the carbonate platform deposits of the liassic calcari grigi group southern alps highlighted how the use of outcrop analogues can contribute to better define the distribution of dolomitic bodies related to fault networks to characterize the petrophysical properties of the dolomitic sequence and unravel a complex diagenetic history this study was carried out in the asiago plateau southernmost part of the eastern southern alps northern italy which provides excellent outcrops of the jurassic calcari grigi group the dolomitization of the jurassic sequence is variable in terms of stratigraphic extension and geographic distribution in the studied localities the dolomitization is generally limited to the mount zugna formation and is characterized by an undulatory front with sub vertical dolomitic chimneys along the major faults within this unit and often associated with faults stacked high porosity and permeability bed parallel dolomitic bodies are developed that show excellent petrophysical properties the dolomitic intervals are characterized by pervasive unimodal and patchy polymodal dolomite crystals thin section cathodoluminescence isotopic and fluid inclusion analyses were used to constrain the paragenetic evolution of the sequence which is similar in all the studied localities the first dolomitization stage is marked by zoned dolomite crystals with a dull luminescent core the porosity is thought to have increased after this stage with dark blue luminescent dolomite accompanied by the corrosion of older crystals the appearance of saddle dolomite marks the onset of the porosity reduction stage ending with the infilling of vugs and the remaining open pores with calcite cement the diagenetic evolution locally stopped at the saddle dolomite stage with the complete occlusion of the remaining pores paragenetic and fluid inclusion data suggest an evolutionary trend of increasing temperatures and decreasing salinity toward brackish fluids responsible for dolomite and calcite precipitation the integration of the available data seem to indicate that the diagenetic evolution of the study area is related to i the interplay between evolving fluids from marine to brackish ii the burial of the sequence increasing temperature and iii the evolution of the hydrogeological system fault and fracture network fluid mixing this complex paragenetic evolution is strongly linked to the evolution of the porosity framework that evolved from a good widespread network in the early stages of the burial history to a confined system in the later stages due to reduction of porosity by the deposition of late calcite and dolomite cements

stress strain and fault behavior at a thrust ramp insights from the naukluft thrust namibia we report observations from a kilometer scale thrust ramp on the naukluft thrust namibia the naukluft thrust is a low angle thrust that was active at subgreenschist facies conditions and accommodated several tens of kilometers of displacement at the base of the naukluft nappe complex in the pan african damara orogeny the fault zone is generally planar and a few meters thick comprising predominantly a dolomite rich cataclasite at the ramp the fault rock assemblage increases in thickness and the hanging wall which elsewhere is relatively intact contains a high density network of inclined quartz veins subvertical dolomite and calcite veins breccia zones as well as injectites of cataclastic fault rock emanating from the fault surface the geometry of the hanging wall structures indicates local subhorizontal extension local tensile stress can be explained by bending in the hanging wall as it deformed to slide above the ramp structure high fluid pressures created dynamically during fast slip by decarbonation of carbonate fault rock and by dewatering of the footwall under an impermeable fault during interseismic periods led to additional reduction in local effective compressive stresses in this location the ramp is more optimally oriented for slip in the inferred regional stress field and therefore likely to fail before the contiguous thrust flats that are subparallel to the maximum principal stress as such the ramp represents the likely location for nucleation of fault slip which could both trigger dynamic failure of the adjacent thrust faults and produce hanging wall extensional structures

quiet time equatorial f region vertical plasma drift model derived from rocsat 1 observations 1 we have used five years of measurements on board the rocsat 1 satellite to develop a detailed quiet time global empirical model for equatorial f region vertical plasma drifts this model describes the local time seasonal and longitudinal dependence of the vertical drifts for an altitude of 600 km under moderate and high solar flux conditions the model results are in excellent agreement with measurements from the jicamarca radar and also from other ground based and in situ probes we show that the longitudinal dependence of the daytime and nighttime vertical drifts is much stronger than reported earlier especially during december and june solstice the late night downward drift velocities are larger in the eastern than in the western hemisphere at all seasons the morning and afternoon december solstice drifts have significantly different longitudinal dependence and the daytime upward drifts have strong wave number four signatures during equinox and june solstice the largest evening upward drifts occur during equinox and december solstice near the american sector the longitudinal variations of the evening prereversal velocity peaks during december and june solstice are anti correlated which further indicates the importance of conductivity effects on the electrodynamics of the equatorial ionosphere

balancing cross sections with kinematic constraints the dolomites northern italy balancing of structural cross sections is often hindered by a limited database or tectonic complications in such cases kinematic constraints may help to better constrain the construction of a cross section and its extrapolation to depth the kinematic implications of a known structure generally at the surface have to be considered for the unknown structure and for the internal consistency of a cross section a key point is the quantification of shortening of the known structure the extrapolation of this parameter allows balancing in an approximate way emphasizing major structures while minor structures are either neglected or treated in a simplified way with this approach a quick overview can be achieved on how much leeway for interpretation exists critical points for testing various working hypotheses become more evident and the trial and error effort during the construction of a balanced section is considerably shortened still the implications the observed structures have on the deeper crustal levels can be assessed this concept is applied to a section across the italian dolomites a brittle fold and thrust belt lacking reflection seismic data so far and thus with a poorly known deep structure still active south vergent alpine thrusting is oriented approximately perpendicular to previous dinaric thrusting the ramp flat style is dominant due to rheological constrasts within the stratigraphic sequence thanks to kinematic balancing based on surface data three alpine thrust systems could be identified each defining a thrust sheet with its particular basement unit and its sedimentary part superposition of the two more external basement units led to the presently observed high elevation of the triassic sequence in the dolomites shortening since late miocene times amounts to more than 50 km retrodeformation of alpine thrusting is a key for better understanding the previous dinaric structures and kinematics

radiography of a normal fault system by 64 000 high precision earthquake locations the 2009 l aquila central italy case study 1 we studied the anatomy of the fault system where the 2009 l aquila earthquake mw 6 1 nucleated by means of 64 k high precision earthquake locations spanning 1 year data were analyzed by combining an automatic picking procedure for p and s waves together with cross correlation and double difference location methods reaching a completeness magnitude for the catalogue equal to 0 7 including 425 clusters of similar earthquakes the fault system is composed by two major faults the high angle l aquila fault and the listric campotosto fault both located in the first 10 km of the upper crust we detect an extraordinary degree of detail in the anatomy of the single fault segments resembling the degree of complexity observed by field geologists on fault outcrops we observe multiple antithetic and synthetic fault segments tens of meters long in both the hanging wall and footwall along with bends and cross fault intersections along the main fault and fault splays the width of the l aquila fault zone varies along strike from 0 3 km where the fault exhibits the simplest geometry and experienced peaks in the slip distribution up to 1 5 km at the fault tips with an increase in the geometrical complexity these characteristics similar to damage zone properties of natural faults underline the key role of aftershocks in fault growth and co seismic rupture propagation processes additionally we interpret the persistent nucleation of similar events at the seismicity cutoff depth as the presence of a rheological i e creeping discontinuity explaining how normal faults detach at depth