on the role of inertial instability in stratosphere troposphere exchange near midlatitude cyclones abstractin simulations of midlatitude cyclones with the university of wisconsin nonhydrostatic modeling system uwnms mesoscale regions with large negative absolute vorticity commonly occur in the upper troposphere and lower stratosphere utls overlying thin layers of air with stratospheric values of ozone and potential vorticity pv these locally enhanced stratosphere troposphere exchange ste events are related to upstream convection by tracing negative equivalent potential vorticity epv anomalies along back trajectories detailed agreement between the patterns of negative absolute vorticity pv and epv each indicators of inertial instability in the utls is shown to occur in association with enhanced ste signatures results are presented for two midlatitude cyclones in the upper midwest where convection develops between the subpolar and subtropical jets mesoscale regions of negative epv air originate upstream in the boundary layer as they are transported through convection epv becomes incre

geometry mechanisms and significance of extensional folds from examples in the rocky mountain basin and range province u s a abstract geologic mapping and structural analysis in paleogene half graben of idaho and montana have revealed over 70 extensional folds that form orthogonal sets with mostly ne and se trending axes on a regional scale they parallel or lie perpendicular to the strikes of the largest normal faults transverse folds at a high angle to the fault and folds oblique to the fault comprise more than half of the folds and reflect the highly three dimensional nature of the bulk strain detailed geometric analysis of 15 folds in the salmon horse prairie and medicine lodge basins shows that they typically have an upright to steeply inclined bisecting surface an interlimb angle of 141 and a plunge of 19 based on our synthesis of the eight common mechanisms of extensional folding and their distinguishing characteristics we were able to determine how some of the investigated folds formed fault bend folding above both fault parallel and fault perpendicular bends in the underlying normal fault produced most of the folds in the study area but displacement gradients along normal faults fault drag isostatic adjustments and transtension were also factors in the deformation most of the compound folds which result from more than one mechanism of folding are oblique to all adjacent normal faults recognition of such extensional folds is critical because they might be misinterpreted as contractional structures they influence sediment thickness patterns and dispersal in rift basins and may control the migration and trapping of petroleum and groundwater resources

localisation of normal faults in multilayer sequences abstract existing conceptual growth models for faults in layered sequences suggest that faults first localise in strong and brittle layers and are later linked in weak and ductile layers we use the discrete element method for modelling the growth of a normal fault in a brittle ductile multilayer sequence the modelling reveals that faults in brittle ductile sequences at low confining pressure and high strength contrast localise first as mode i fractures in the brittle layers low amplitude monoclinal folding prior to failure is accommodated by ductile flow in the weak layers the initially vertically segmented fault arrays are later linked via shallow dipping faults in the weak layers faults localise therefore as geometrically and kinematically coherent arrays of fault segments in which abandoned fault tips or splays are a product of the strain localisation process and do not necessarily indicate linkage of initially isolated faults the modelling suggests that fault tip lines in layered sequences are more advanced in the strong layers compared with weak layers where the difference in propagation distance is most likely related to strength and or ductility contrast layer dependent variations in fault localisation rates generate fringed rather than smooth fault tip lines in multilayers

seismo ionospheric coupling appearing as equatorial electron density enhancements observed via demeter electron density measurements we report the processes and results of statistical analysis on the ionospheric electron density data measured by the detection of electro magnetic emissions transmitted from earthquake regions demeter satellite over a period of 6 years 2005 2010 in order to investigate the correlation between seismic activity and equatorial plasma density variations to simplify the analysis three equatorial regions with frequent earthquakes were selected and then one dimensional time series analysis between the daily seismic activity indices and the equatorial ionization anomaly eia intensity indices which represent relative equatorial electron density increase were performed for each region the statistically significant values of the lagged cross correlation function particularly in the region with minimal effects of longitudinal asymmetry indicate that some of the very large earthquakes with m 5 0 in the low latitude region can accompany observable precursory and concurrent eia enhancements even though the seismic activity is not the most significant driver of the equatorial ionospheric evolution the physical mechanisms of the seismo ionospheric coupling is consistent with our observation and the possibility of earthquake prediction using the eia intensity variation is discussed

origin dimensions and distribution of remobilized carbonate deposits in a tectonically active zone eocene thebes formation sinai egypt abstract determination of the distribution and mechanism for carbonate dominated mass transport sediments is often compromised by the scale and access to exposures consequently many studies lack the resolution to capture the heterogeneity and dimensions of mass transport deposits this study documents the size shape and stratal assemblage of remobilized carbonates in the eocene thebes formation in the hammam faraun fault block hffb of western sinai revealing the complexities of carbonate mass transport deposits at sub seismic scale present day pseudo three dimensional exposure of the thebes formation in a large fault block formed during the opening of the gulf of suez allowed for lateral and down dip measurement of slope and basinal facies in the field and from photos remobilized facies were digitized in the photos and evaluated using image analysis software a technique with a wide range of applications to outcrop studies of sedimentary architecture debris flow deposits in the lower section of the thebes formation comprises clasts with differing fossil assemblages a relative sea level rise at the start of upper thebes formation deposition resulted in basinal sediments comprising periodic incursions of high density turbidite grainstones encased within a background of planktonic foraminiferal wackestones foraminiferal assemblages of remobilized facies imply multiple sources on the carbonate platform demonstrating the effect of short lived tectonism on slope instability and deposition of mass transport deposits the results of the study confirm that tectonism associated with the syrian arc fold belt which altered the style of basin sedimentation between egypt and syria persisted into the eocene at least as far south as wadi araba in the western desert and hammam faraun in sinai in addition the shape size and extent of the two dominant remobilized facies debris flows and grainstone turbidites are influenced by their mud rich versus grainy compositions

chemical and dynamical discontinuity at the extratropical tropopause based on start08 and waccm analyses 1 using isentropic trace gas gradients of o3 and co the discontinuity in the chemical composition of the upper troposphere ut and lower stratosphere ls is examined on middle world isentropes from 300 to 380 k the analysis is a follow up study of the dynamical discontinuity as represented by the potential vorticity pv gradient based tropopause which is based on the product of isentropic pv gradients and wind speed overall there is fairly good consistency between the chemical discontinuity in trace gas distributions and the pv gradient based tropopause trace gas gradients at the pv gradient based tropopause are stronger in winter than in summer revealing the seasonal cycle of the tropopause transport barrier the analysis of the trace gas gradients also identifies atmospheric transport pathways in the upper troposphere lower stratosphere utls several regions where trace gas gradients are found to be decoupled from the dynamical field indicate preferred transport pathways between the ut and ls in particular anomalous co and o3 gradients above eastern africa eastern asia and the west pacific are likely related to convective transport and anomalous o3 gradients over the north atlantic and north pacific are related to isentropic transport connected to frequent wave breaking the results indicate that the pv gradient based tropopause definition provides a good identification of the dynamical and chemical discontinuity and is therefore effective in locating the physical boundary in the utls

tectonic and sedimentary evolution of the gulf of suez and the northwestern red sea abstract the structural pattern of the gulf of suez and red sea rift is inherited from the basement tectonics n140 faults clysmic direction parallel to the regional elongation of the rift are associated with submeridian aqaba direction and sub e w faults duwi direction that also play an important role in the rifting processes the pre rift sedimentary cover includes cretaceous and eocene platform deposits it was slightly deformed prior to rifting the syn rift sedimentary sequence comprises four major units groups a to d delimited by unconformities group a oligocene to early burdigalian continental to restricted subaquatic deposits group b burdigalian to middle miocene open marine sediments group c middle to upper miocene major evaporitic episode and group d plio pleistocene which returns to an open marine environment four majors stages of structuration are recorded an initial stage of compressive deformation direction of shortening close to nw se characterized by strike slip movements and associated drag folds early group a a tilted block stage late group a corresponding to the period of highest extensional rate a horst and graben stage group b resulting in the cutting out of the tilted blocks by numerous synthetic faults group b corresponds to the period of highest subsidence rate when a flexuration stage of the margin expressed by a centripetal evolution of the subsidence is associated with major periferal uplift

bedding plane slip in initial stages of fault related folding abstract frictional slip along bedding planes contributes to fault related folding of layered rocks we use numerical experiments to investigate the deformation of frictional bedding planes near dipping faults under layerparallel contraction and extension within the numerical experiments contraction boundary conditions produce asymmetric anticlines and extension produces asymmetric synclines the fold shape may be used to infer dip of the underlying fault in situations where the fault may not be observable additionally sense of slip along bedding planes may indicate proximity to the fault tip under uniform remote tectonic strain fault slip induces deformation in both the hangingwall and the footwall at depths as shallow as 1 km there is no significant difference between fold amplitudes in the hangingwall and the footwall this result is contrary to many kinematic models currently in use kinematic models of fault related folds commonly include the development of flat ramp and flat ramp flat fault geometries which may be attributed to initial ramp thrusting and later flat development our mechanical models show that fault flats may be produced from fault ramps due to slip along frictional bedding planes near the thrust fault tips our numerical experiments also evaluate joint initiation joints perpendicular to bedding are promoted in extensional environments we compare the results of the mechanical model to kinematic models of fault propagation folds and conclude that mechanical models offer important insights to better understand the folding process

a model for the structure and development of fault zones cross sections of fault zones commonly show two sub parallel slip surfaces which bound more or less deformed rock this characteristic geometry can be explained by a combination of 9tip line9 and 9asperity9 bifurcation processes fault tip line bifurcation is due to irregular tip line propagation resulting in leading edge segmentation fault overlap and eventual duplex formation asperity bifurcation removes a fault surface irregularity by the generation of a new slip surface which by passes the original slip surface repetitions of either or both bifurcation processes give rise to a fault zone with a complex and unpredictable internal geometry these processes are described mainly on the basis of observation of normal faults hut can be applied to other fault types fault zone thickening by bifurcation is intermittent rather than progressive and localised fault zone thinning may occur

fault relays bends and branch lines abstract branch lines between normal faults and their sub parallel splays mapped from 3d seismic reflection data show a range of forms from straight lines to closed loops the different geometries are interpreted as representing stages in the failure of relay zones and in the progressive replacement of fault tip lines with fault branch lines the geometries of these normal fault branch lines are similar to those for thrusts previously inferred from limited two dimensional data the orientation of the axis of a relay and its associated bends relative to a fault slip direction is identified as an important control on the structures developed within the relay neutral restraining and releasing bends can each occur on any fault type normal reverse and strike slip but data bias is a major factor in determining which bend geometry is most often observed with each fault type on normal faults the initial relay zone geometry controls the dominant branch line orientation and the same control is likely on branch lines associated with the other modes of faulting a review of the relay geometries and strains occurring with all three modes of faulting highlights the role of the orientation of the mechanical anisotropy of a bedded sequence relative to the orientations of fault surface and slip directions this relative orientation determines how the relay strain is accommodated and hence the degree of hard linkage and development of branch lines

structural geology and 4d evolution of a half graben new digital outcrop modelling techniques applied to the nukhul half graben suez rift egypt abstract lidar based digital outcrop mapping in conjunction with a new surface modelling approach specifically designed to deal with outcrop datasets is used to examine the evolution of a half graben scale normal fault array in the suez rift syn rift deposition in the nukhul half graben was controlled by the graben bounding nukhul fault the fault can be divided into four segments based on the strike of the fault the morphology of hangingwall strata and the variation in throw along strike the segments of the fault became geometrically linked within the first 2 5 m y of rifting as evidenced by the presence of early syn rift abu zenima formation strata at the segment linkage points fault perpendicular folds in the hangingwall related to along strike variations in throw associated with precursor fault segments persist for a further 1 8 m y after linkage of the segments suggesting that the fault remains kinematically segmented we suggest this occurs because of sudden changes in fault strike at the segment linkage points that inhibit earthquake rupture propagation or because displacement is geometrically inhibited at fault linkage points where the orientation of the intersection line of the segments is significantly different from the orientation of the slip vector on the fault system length throw plots and throw contour patterns for minor faults show that some faults initiated in pre rift strata whereas late east striking faults initiated in the syn rift basin fill the late initiating faults are spatially associated with the east striking baba markha fault which was active throughout the rift history but developed as a transfer fault between major block bounding fault systems around 6 7 ma after rift initiation

fault propagation folding in extensional settings examples of structural style and synrift sedimentary response from the suez rift sinai egypt field data from the oligocene miocene gulf of suez rift demonstrate that coeval growth faults folds and transfer zones exerted a major control on synrift stratigraphic sequence development growth folds in the suez rift are related to steeply dipping normal faults that propagated upward resulting in broad upward widening monoclines in overlying strata folding during fault propagation was accommodated by layer parallel slip and detachment along mudstone horizons as well as by normal and rare reverse secondary faults that propagated away from the master fault the eventual propagation of the master fault through to the surface left the steep limb of the monocline and most of the secondary faults in the hanging wall this evolving structural style exerted a marked control on the geometry and stacking patterns of coeval synrift sediments synrift sediments display onlap and intraformational unconformities toward the growth monoclines and buried faults whereas they diverge into broadly synclinal expanded sections away from the growth monocline continued movement across buried faults resulted in the progressive rotation of the monoclinal limb and associated synrift sediments each successively younger sequence dipping basinward at a shallower angle than the previous one the resulting synrift geometries differ significantly from stratal geometries normally anticipated adjacent to normal faults along strike variations in facies stacking patterns are also commonly associated with decreasing displacement across faults and associated folds toward low relief transfer zones data from other rift basins indicate that fault propagation folds are not unique to the gulf of suez

geometry and development of relay ramps in normal fault systems relay ramps occur between normal fault segments that overstep in map view the geometry and evolution of exposure scale relay ramps are described from the somerset coast england and are compared with larger scale ramps from elsewhere relay ramps can be classified into four groups based on the degree of interaction and linkage between the overstepping segments these groups are interpreted as being evolutionary stages in stage 1 the segments do not interact stage 2 involves the reorientation of bedding between two interacting faults to produce a relay ramp in stage 3 connecting fractures start to break the relay ramp stage 4 is when the relay ramp is destroyed to produce a single fault that has an along strike bend these evolutionary stages can develop through ti e but they can also be seen spatially a branch line between normal faults or an along strike bend may represent a stage 4 relay with progressively earlier stages occurring updip or downdip characteristic variability in displacement distance profiles for fault segments and linked faults accompanies the interaction and linkage processes displacement transfer by relay ramps is accompanied by steep displacement gradients along fault segments at oversteps relay ramps often contribute to a minimum in total fault displacement at a linkage point

ground based and uav based photogrammetry a multi scale high resolution mapping tool for structural geology and paleoseismology this contribution reviews the use of modern 3d photo based surface reconstruction techniques for high fidelity surveys of trenches rock exposures and hand specimens to highlight their potential for paleoseismology and structural geology we outline the general approach to data acquisition and processing using ground based photographs acquired from standard dslr cameras and illustrate the use of similar processing approaches on imagery from unmanned aerial vehicles uavs it is shown that digital map and trench data can be acquired at ultra high resolution and in much shorter time intervals than would be normally achievable through conventional grid mapping the resulting point clouds and textured models are inherently multidimensional x y z point orientation colour texture archival and easily transformed into orthorectified photomosaics or digital elevation models dems we provide some examples for the use of such techniques in structural geology and paleoseismology while pointing the interested reader to free and commercial software packages for data processing visualization and 3d interpretation photogrammetric models serve to act as an ideal electronic repository for critical outcrops and observations similar to the electronic lab book approach employed in the biosciences this paper also highlights future possibilities for rapid semi automatic to automatic interpretation of the data and advances in technology

geometry and architecture of faults in a syn rift normal fault array the nukhul half graben suez rift egypt the geometry and architecture of a well exposed syn rift normal fault array in the suez rift is examined at pre rift level the nukhul fault consists of a single zone of intense deformation up to 10 m wide with a significant monocline in the hanging wall and much more limited folding in the footwall at syn rift level the fault zone is characterised by a single discrete fault zone less than 2 m wide with damage zone faults up to approximately 200 m into the hanging wall and with no significant monocline developed the evolution of the fault from a buried structure with associated fault propagation folding to a surface breaking structure with associated surface faulting has led to enhanced bedding parallel slip at lower levels that is absent at higher levels strain is enhanced at breached relay ramps and bends inherited from pre existing structures that were reactivated during rifting damage zone faults observed within the pre rift show ramp flat geometries associated with contrast in competency of the layers cut and commonly contain zones of scaly shale or clay smear damage zone faults within the syn rift are commonly very straight and may be discrete fault planes with no visible fault rock at the scale of observation or contain relatively thin and simple zones of scaly shale or gouge the geometric and architectural evolution of the fault array is interpreted to be the result of i the evolution from distributed trishear deformation during upward propagation of buried fault tips to surface faulting after faults breach the surface ii differences in deformation response between lithified pre rift units that display high competence contrasts during deformation and unlithified syn rift units that display low competence contrasts during deformation and iii the history of segmentation growth and linkage of the faults that make up the fault array this has important implications for fluid flow in fault zones

discrete element modelling of contractional fault propagation folding above rigid basement fault blocks many studies have shown that discrete blind faults at depth are commonly linked to more distributed deformation in particular folding at higher levels one category of fault related folds forced folds is common where there is a distinct mechanical contrast between faulted basement and sedimentary cover outcrop numerical and analogue modelling studies indicate that such folds form as upward widening zones of distributed deformation monoclines above discrete faults at depth with increasing displacement the folds are often cut by faults as they propagate upwards into the cover while the trishear kinematic model of fault propagation folding appears to approximately represent the geometric development of such structures comparatively little is known of the mechanical controls on their development here we present a 2d discrete element model of sedimentary cover deformation above a contractional fault in rigid basement the elements consist of a series of soft spheres that obey newton s equations of motion and initially interact with elastic forces under the influence of gravity particles are bonded until the separation between them exceeds a defined breaking strain at which time the bond breaks simulated by the transition from repulsive attractive forces to solely repulsive forces the model is used to investigate the influence of basement fault dip and sedimentary cover strength on the geometry of the folds developed and the rate of fault propagation in all cases an upward widening monocline occurs above the basement fault we find that shallow basement fault dips produce homogenous thickening of the monocline limb while steeper dips produce contemporaneous thinning and thickening within the monocline thinning and thickening within the monocline are accommodated by a combination of small scale faulting and folding with decreasing cover strength the zone of deformation becomes wider localization does not occur on a single fault and fold geometries resemble trishear fold profiles with low propagation to slip ratios p s 1 in contrast a stronger cover produces a narrower zone of deformation localization on a single fault and more rapid fault propagation similar to trishear fold profiles where p s 2 3 the fault propagates into the cover at approximately the same angle as the basement fault the model reproduces well many of the features observed in analogue modelling and reported from outcrop and seismic studies

characteristics and possible source of a 1479 a d volcanic ash layer in a greenland ice core abstract a microparticle concentration peak in a gisp2 ice core contains volcanic glass shards of rhyolitic composition that correspond in age to the 1479 1480 a d mt st helens wn eruption these glass shards are compositionally similar to the wn tephra and constitute 83 of the total particle population the shards are very coarse grained up to 40 m diameter suggesting rapid transport from their source to greenland a major sulfate peak in the ice occurs approximately 4 months after deposition of the glass shards this difference in depositional timing suggests primarily tropospheric transport of the ash and stratospheric transport of the sulfate aerosol large scale climatic perturbations following this eruption were evidently negligible glaciochemical seasonal indicators suggest a late fall to early winter 1479 a d eruption

interactions of north pacific tropical midlatitude and polar disturbances resulting in linked extreme weather events over north america in october 2007 abstractthis study uses observations and model reanalyses to examine the multiscale processes associated with four high impact extreme weather events ewes over north america during late october 2007 the ewes consisted of wind driven wildfires in california prolonged anomalous cold conditions in mexico linked to two cold surges heavy rainfall in the eastern united states and severe flood producing heavy rainfall in southern mexico the ewes involved a pronounced large scale flow reconfiguration across the north pacific and north america in conjunction with the formation of a high amplitude rossby wave train the flow reconfiguration involved perturbations to the north pacific jet stream linked to polar midlatitude and tropical disturbances including three tropopause level polar disturbances originating over northeastern asia transient extratropical cyclones a diabatic rossby vortex and western north pacific tropical cyclone kajiki eulerian and lagrangian diagnostics indicate that ridge amplifi

observed trends in the global jet stream characteristics during the second half of the 20th century 1 in this paper we propose a new method based on the detection of jet cores with the aim to describe the climatological features of the jet streams and to estimate their trends in latitude altitude and velocity in the national centers for environmental prediction ncep national center for atmospheric research ncar and 20th century reanalysis data sets due to the fact that the detection method uses a single grid point to define the position of jet cores our results reveal a greater latitudinal definition allowing a more accurate picture of the split flow configurations and double jet structures to the best of our knowledge these results provide the first multiseasonal and global trend analysis of jet streams based on a daily resolution 3 d detection algorithm trends have been analyzed over 1958 2008 and during the post satellite period 1979 2008 we found that in general trends in jet velocities and latitudes have been faster for the southern hemisphere jets and especially for the southern polar front jet which has experienced the fastest velocity increase and poleward shift over 1979 2008 during the austral summer and autumn results presented here show an acceleration and a poleward shift of the northern and southern winter subtropical jets over 1979 2008 that occur at a faster rate and over larger zonally extended regions during this latter period than during 1958 2008

fastex iop 18 a very deep tropopause fold i synoptic description and modelling the life cycle of a very deep tropopause fold 820 hpa is documented with aircraft and ship observations during the intensive observing period 18 of the fronts and atlantic storm track experiment fastex the initial setting involves a coherent tropopause disturbance and an associated arctic tropopause fold the confluence episode that results from the phasing up of the tropopause disturbance and a southern ridge ends in the formation of an intense jet streak the dynamics of which are associated with the development of a polar tropopause fold a diagnostic analysis suggests that the final dramatic stratospheric intrusion is the consequence of the vertical superposition of the arctic and polar tropopause folds the mesoscale non hydrostatic meso nh model is used to discuss this hypothesis mixing of the passive stratospheric tracer within the marine boundary layer is investigated with sensitivity tests which unplug in turn the model physical parametrizations finally upper level forcings associated with the development of the tropopause fold are investigated in detail in a companion paper

the arctic tropopause fold abstract analyses of research aircraft observation satellite total columnar ozone retrievals and synoptic upper air soundings are used to describe the structure of arctic jetstreams and their associated frontal zones and tropopause folds these analyses document the presence of major tropopause folding events within the arctic that occur at the flanks of large scale 2000 km polar vortices one example shows a polar vortex and its associated tropopause fold and arctic front that migrated from the high canadian arctic southward into midlatitudes over central north america the frigid cold air outbreak associated with this migration was an important component in the record setting daily minimum temperatures that were recorded from the great lakes to southern florida total columnar ozone measurements from the total ozone mapping spectrometer toms are shown to identify the location of polar vortices and the mesoscale 200 km ozone gradients at the flanks of these vortices which coincide with regions o

the ionospheric anomalies prior to the m9 0 tohoku oki earthquake the gps total electron content tec data were used to investigate the ionospheric abnormal behaviors prior to the 2011 tohoku oki earthquake the observations show a significant enhancement in tec on march 8 2011 and during the same period the solar activity also has a large increase both an empirical model and a theoretical model were used to check whether the tec anomalies were entirely contributed by the increase in solar radiation the comparison between the observations and the simulation results shows that only the solar radiation enhancement was not enough to produce the observed significant tec enhancement it means that some additional mechanisms such as the per earthquake ionospheric disturbance or the geomagnetic activities may play a significant role in the significant tec enhancement on march 8 the temporal spatial distribution of the extreme tec enhancement within 30 days before the earthquake was particularly pursued it is found that the extreme enhancement was persistently located in the region adjacent to the epicenter and the magnetic conjugate point for a long time of 16 h in addition a geomagnetic disturbance with kp 4 occurred on march 7 therefore the significant tec enhancement on march 8 might be related to the m9 0 tohoku oki earthquake and the geomagnetic disturbance

using tropopause maps to diagnose midlatitude weather systems the use of potential vorticity pv allows the efficient description of the dynamics of nearly balanced atmospheric flow phenomena but the distribution of pv must be simply represented for ease in interpretation representations of pv on isentropic or isobaric surfaces can be cumbersome as analyses of several surfaces spanning the troposphere must be constructed to fully apprehend the complete pv distribution following a brief review of the relationship between pv and nearly balanced flows it is demonstrated that the tropospheric pv has a simple distribution and as a consequence an analysis of potential temperature along the dynamic tropopause here defined as a surface of constant pv allows for a simple representation of the upper tropospheric and lower stratospheric pv the construction and interpretation of these tropopause maps which may be termed isertelic analyses of potential temperature are described in addition techniques to construct dynamical representations of the lower tropospheric pv and near surface potential temperature which complement these isertelic analyses are also suggested case studies are presented to illustrate the utility of these techniques in diagnosing phenomena such as cyclogenesis tropopause folds the formation of an upper trough and the effects of latent heat release on the upper and lower troposphere

temporal and spatial precursors in ionospheric total electron content of the 16 october 1999 mw7 1 hector mine earthquake 1 in this paper temporal and spatial analyses are employed to detect seismo ionospheric precursors sips in the ionospheric total electron content tec during the 16 october 1999 mw7 1 hector mine earthquake to discriminate anomalies caused by global effects such as solar radiations magnetic storms etc and local effects such as earthquake we cross examine the gps tecs and their gradients in the eastward and northward directions at epicenter centers of the hector mine area and the other two reference areas at similar magnetic latitudes in europe and japan temporal variations of the northward tec gradient suggest sips most likely appearing on days 6 5 before the earthquake a global search by using the tec of the global ionosphere map shows that the tec increase and decrease anomalies continuously and specifically appear around the epicenter on day 5 before the earthquake

an observational study of an arctic front during he ipy thorpex 2008 campaign the fact that severe weather associated with polar lows and arctic fronts still comes unforeseen and puts human life at risk shows that an effort towards increased understanding of them is required the observations of an arctic front by dropsondes and doppler lidar carried onboard a research aircraft during the ipy thorpex field campaign offered a rare opportunity to investigate the mesoscale structure of the front and to validate the output from operational numerical weather prediction models the observations revealed features similar to those of polar fronts such as a relatively steep frontal zone the presence of a strong low level jet and an elevated dry slot making the arctic front appear as a shallow cold front confined to levels below 700 hpa the dry slot indicated the presence of a downfolding of the tropopause and together with the observations of an upper level jet this strongly supports the inclusion of an arctic tropopause fold connected to the arctic jet stream in a conceptual model of the tropopause a comparison between data from operational numerical weather prediction models and observations obtained during the flight shows that the models simulated the broad features of the frontal zone such as jets dry slot and the depth of the front fairly well although parts of the front were slightly misplaced however the models failed completely in their simulations of one of the three mesoscale cyclones associated with the front as they located it over the coast of northern norway while the correct location was over the greenland sea according to the observations and analysis

climatology of cyclogenesis mechanisms in the mediterranean abstract a general climatology of the main mechanisms involved in mediterranean cyclogenesis is presented a diagnostic study of both composite means and case studies is performed to analyze processes occurring in different seasons and in different cyclogenetic regions within the same season it is shown that cyclones that developed over the three most active areas in winter the gulf of genoa the aegean sea and the black sea are essentially subsynoptic lows triggered by the major north atlantic synoptic systems being affected by local orography and or low level baroclinicity over the northern mediterranean coast it is also suggested that cyclones in two or all three of these regions often occur consecutively linked to the same synoptic system in spring and summer thermally induced lows become progressively more important despite the existence of other factors such as the atlas mountains contributing to lee cyclogenesis in northern africa or the extension of the asian monsoon into the eastern

observations and simulations of seismoionospheric gps total electron content anomalies before the 12 january 2010 m7 haiti earthquake 1 in this paper the total electron content tec of the global ionosphere map gim is used to detect seismoionospheric anomalies associated with the 12 january 2010 m7 haiti earthquake and an ionospheric model is applied to simulate the detected anomalies the gim temporal variation shows that the tec over the epicenter significantly enhances on 11 january 2010 1 day before the earthquake the latitude time tec ltt plots reveal three anomalies 1 the northern crest of equatorial ionization anomaly eia moves poleward 2 the tecs at the epicenter and its conjugate increase and 3 the tecs at two dense bands in the midlatitude ionosphere of 35 n and 60 s further enhance the spatial analysis demonstrates that the tec enhancement anomaly appears specifically and persistently in a small region of the northern epicenter area the simulation well reproduces the three gim tec anomalies which indicate that the dynamoelectric field of the ionospheric plasma fountain might have been perturbed by seismoelectric signals generated around the epicenter during the earthquake preparation period

variations of ionospheric total electron content during the chi chi earthquake on 20 september1999 ut 21 septemberin local time lt a large earthquake mw 7 7 struck central taiwan nearthe small town of chi chi the greatest plasma frequency in the ionosphere fof2 observed by the chung li ionosonde 25 0 n 121 2 e reveals three clear precur sors at 1 3 and 4 days prior to the earthquake this paper examines the ionospheric total electron content tec ob served by a network of the global positioning system gps receivers in taiwan area it is found that variations in fof2 and overhead tec recorded at chung li have a similar ten dency combining the data of the network of 13 gps re ceivers time and spatial variations of tec prior to the chi chi earthquake are examined results show that the equa torial anomaly crest moves equatorward and its tec value significantly decreases 1 3 and 4 days before the earth quake a comparison between the disturbed and reference previous 15 day median days confirms that tec decreases significantly around the epicenter in the afternoons of these days finally possible mechanisms are proposed and dis cussed

convective injection into stratospheric intrusions 1 stratospheric intrusions tropopause folds are known to be major contributors to stratosphere troposphere exchange the specific mixing processes that lead to irreversible exchange between stratospheric intrusions and the surrounding troposphere however are not entirely understood this study presents direct observations of moist convection penetrating into stratospheric intrusions the characteristics of convective injection are shown by using in situ aircraft measurements radar reflectivities and model analyses convective injection is observed at altitudes up to 5 km above the bottom of a stratospheric intrusion aircraft measurements from the stratosphere troposphere analyses of regional transport 2008 start08 experiment show that convective injection in stratospheric intrusions can be uniquely identified by coincident observations of water vapor greater than about 100 ppmv and ozone greater than about 125 ppbv trajectory analyses show that convective injection can impact transport in both directions from troposphere to stratosphere and from stratosphere to troposphere we present a conceptual model of the synoptic meteorological conditions conducive to convective injection in stratospheric intrusions in particular convective injection is found to be associated with a split front where the upper level frontal boundary outruns the surface cold front

time resolved study of charge generation and propagation in igneous rocks electrical resistivity changes ground potentials electromagnetic em and luminous signals preceding or accompanying earthquakes have been reported many times in addition to ground uplift and tilt and other parameters however no concept exists that would tie these diverse phenomena together into a physically coherent model using low to medium velocity impacts to measure electrical signals with microsecond time resolution it is observed that when gabbro and diorite cores are impacted at relatively low velocities 100 m s highly mobile charge carriers are generated in a small volume near the impact point they spread through the rocks causing electric potentials exceeding 400 mv em and light emission as the charge cloud spreads the rock becomes momentarily conductive when a granite block is impacted at higher velocity 1 5 km s the propagation of the p and s waves is registered through the transient piezoelectric response of quartz after the sound waves have passed the surface of the granite block becomes positively charged suggesting the same charge carriers as observed during the low velocity impact experiments expanding from within the bulk during the next 2 3 ms the surface potential oscillates indicating pulses of electrons injected from ground and contact electrodes the observations are consistent with positive holes e g defect electrons in the o2 sublattice traveling via the o 2p dominated valence band of the silicate minerals the positive holes propagate as charge clouds rather than as classical em waves before activation they lay dormant in form of electrically inactive positive hole pairs php chemically equivalent to peroxy links o3x oo xo3 with x si4 al3 etc phps are introduced into the minerals by way of hydroxyl o3x oh which all nominally anhydrous minerals incorporate when crystallizing in h2o laden environments the fact that positive holes can be activated by low energy impacts and their attendant sound waves suggests that they can also be activated in the crust by microfractures during the dilatancy phase depending on where in the stressed rock volume the charge carriers are activated they will form rapidly moving or fluctuating charge clouds that can account for earthquake related electrical signals and em emission wherever such charge clouds intersect the surface high fields are expected causing electric discharges and earthquake lights

characteristics of tropopause folds over arctic latitudes 1 characteristics of tropopause folds over arctic latitudes have been studied using vhf radar measurements supplemented by balloon measurements the variation of the radar parameters during the passage of tropopause folds is discussed in detail to our knowledge these observations constitute the first spaced antenna sa radar measurements during the passage of tropopause folds this allows us to compare the parameters detectable using this mode with those observed using other configurations such as the doppler beam swinging dbs technique in general the structural characteristics such as the slope of folds seem to be similar at arctic latitudes to that at midlatitudes however the height of the tropopause and the axis of the jet stream and hence the folding are found to be lower by 1 2 km than their counterparts in midlatitudes in the case studies the radar derived parameters such as the signal to noise ratio snr and vertical shear of horizontal wind clearly show the upper air frontal zone the frontal circulation conceived from vertical velocity including the warm conveyer belt flow and the dry intrusion is clearly visible in the first case whereas it is masked by high amplitude mountain lee waves in the second case further the frontal zone seems to be acting as a critical layer to mountain lee wave activity by absorbing filtering the wave activity the aspect angles derived from the present analysis agree well with those estimated by vertical beam spectral width but are small in comparison with those estimated by the power ratio method the mean full correlation analysis fca turbulent velocity is estimated using the esrad data obtained during the passage of 15 tropopause folds the mean eddy diffusion coefficients kz near the tropopause and in the upper portion of the fold where strong turbulence is seen in case studies are found to be 3 54 and 6 4 m2 s 1 respectively utilizing the mean kz and the mean ozone gradient obtained from ozonesondes values the ozone fluxes across the tropopause and topside of the fold due to turbulence are estimated as 0 71 m s 1 ppbv and 0 32 m s 1 ppbv respectively although the flux across the tropopause is more than that occurring near the fold the exchange occurring through folds could be more significant to the tropospheric chemical budget

storm time dependence of equatorial disturbance dynamo zonal electric fields we use jicamarca radar observations of f region vertical plasma drifts and auroral electrojet indices during 1968 1988 to study the characteristics and temporal evolution of equatorial disturbance dynamo zonal electric fields these electric fields result from the dynamo action of storm time winds and or thermospheric composition changes driven by enhanced energy deposition into the high latitude ionosphere during geomagnetically active conditions the equatorial vertical drift perturbations last for periods of up to 30 hours after large increases in the high latitude currents on the average this process can be described by two basic components with time delays of about 1 12 hours and 22 28 hours between the high latitude current enhancements and the equatorial velocity perturbations our data indicate strong coupling between dynamo processes with different timescales the short term disturbance dynamo drives upward equatorial drifts eastward electric fields at night with largest amplitudes near sunrise and small downward drifts during the day these perturbation drifts are in good agreement with results from the blanc richmond disturbance dynamo theory the dynamo process with time delays of about a day drives upward drift velocities at night with largest values near midnight and downward drifts in the sunrise noon sector in this case the amplitudes of the disturbance drifts maximize during geomagnetically quiet times preceded by strongly disturbed conditions we also present results of a new equatorial storm time dependent empirical model which illustrate the characteristics of the vertical disturbance dynamo drifts

high resolution record of displacement accumulation on an active normal fault implications for models of slip accumulation during repeated earthquakes the spatial and temporal accumulation of slip from multiple earthquake cycles on active faults is poorly understood here we describe a methodology that can determine the time period of observation necessary to reliably constrain fault behaviour using a high resolution longtimescale the last 17 kyr fault displacement dataset over the rangitaiki fault whakatane graben new zealand the fault linked at ca 300 ka bp and analysis of time periods within the last 17 kyr gives insight into steady state behaviour for time intervals as short as ca 2 kyr the maximum displacement rate observed on the rangitaiki fault is 3 6g1 1 mm yr k1 measured over 17 kyr displacement profiles of the last 9 ka of fault movement are similar to profiles showing the last 300 ka offault movement in contrast profiles determined for short time intervals 2 3 kyr are highly irregular and show points of zero displacement on the larger segments this indicates temporal and spatial variability in incremental displacement associated with surface rupturing slip events there is spatial variability in slip rates along fault segments with minima at locations of fault interaction or where fault linkage has occurred in the past this evidence suggests that some earthquakes appear to have been confined to specific segments whereas larger composite ruptures have involved the entire fault the short term variability in fault behaviour suggests that fault activity rates inferred from geodetic surveys or surface ruptures from a single earthquake may not adequately represent the longer term activity nor reflect its future behaviour different magnitude events may occur along the same fault segment with asperities preventing whole segment rupture for smaller magnitude events q 2006 elsevier ltd all rights reserved

aircraft measurements of potential vorticity and richardson number in baroclinic zones this paper describes a novel technique for deriving potential vorticity and richardson number from aircraft cross sections of baroclinic zones it exploits the fact that gravity waves distort isentropic surfaces so that an aircraft flying horizontally can measure a vertical profile of temperature and wind under favourable conditions the technique is applied to two flights of the uk meteorological research flight s c 130 hercules aircraft in april 1983 and june 1991 it is found to work reasonably well only when large amplitude gravity waves are present values of potential vorticity so derived agree with those calculated in the conventional manner from cross sections and are found to correlate well with ozone mixing ratio

influence of mechanical stratigraphy and initial stress state on the formation of two fault propagation folds abstract kinematic and mechanical modeling of the rip van winkle se new york usa and la zeta sw mendoza argentina anticlines illustrate the influence of mechanical stratigraphy and initial stress state on the kinematics of fault propagation folding in both anticlines faults nucleating at distinct stratigraphic levels open upward into triangular zones of folding folding intensity and finite strain attenuates with distance from the fault tip trishear reproduces the bulk geometry and finite strain of the relatively homogeneous limestone sequence of the rip van winkle anticline and predicts an initial location of the fault tip consistent with the field observations folding of the heterogeneous sedimentary section of la zeta anticline however cannot be simulated by the trishear model alone an additional mode of deformation involving transport of material from the backlimb into the hinge area and extension parallel to the direction of fault propagation is necessary to reproduce the geometry and finite strain of the anticline mechanical distinct element modeling dem of the anticlines indicates that their contrasting kinematics could have resulted from differences in mechanical stratigraphy and initial stress state folding of a homogenous normally consolidated assemblage initial horizontal to vertical stress ratio k o 1 is trishear like and resembles the rip van winkle anticline folding of a heterogenous layered such as la zeta over consolidated assemblage k o 1 departs from the trishear model and resembles la zeta anticline based on the dem simulations we postulate that the rip van winkle anticline formed at high depths high overburden loads and lithostatic stress conditions and that la zeta anticline formed at shallow depths after substantial uplift and erosion of the andean mountain front which induced over consolidation and high k o

the gulf of suez northern red sea neogene rift a quantitive basin analysis abstract subsidence analysis backstripping was carried out on a series of wells from the gulf of suez and northern red sea region of egypt in order to examine the interplay between tectonic events basin subsidence sedimentation and sea level changes in a young developing ocean basin and continental margin using constraints on chronostratigraphy and paleodepth from various sources combined with stratigraphic and structural information from industry wells and other geophysical sources it has been possible to compile the data necessary to perform geohistory analyses throughout the region major subsidence due to crustal thinning began 25 ma with sedimentation initially occurring in isolated sub basins these earliest sediments record the transition from continental to marine depositional environments subsequently during early and middle miocene times subsidence was rapid and uniform along and across the entire rift basin open marine sedimentation occurred across all structural regimes the mid clysmic tectonic event 16 5 ma resulted in structural rearrangement of the rift basin and uplift of the rift shoulders rapid subsidence continued as global sea level fell producing a series of prograding siliciclastic fan deltas at the rift margins at 15 5 ma opening of the suez rift was terminated tectonic subsidence decreased dramatically in the southern rift and ceased entirely in the northern rift tensional plate motion probably was transferred from the gulf of suez to sinistral strike slip movement on the dead sea transform at this time the quiescence in subsidence combined with a lowered global sea level resulted in the deposition of a thick up to 4 km series of evaporites within the central trough of the rift from the middle to latest miocene the accumulation of such a thick sequence of sediments during a phase of decreased tectonic subsidence is interpreted as a filling in of the rift topography which developed during the earlier period of rapid subsidence and rift shoulder uplift and continued compaction a rapid global sea level rise concomitant with a subsequent pulse of increased tectonic activity in the latest miocene earliest pliocene returned the rift to dominantly marine conditions

internal structure and deformation of an accommodation zone in the northern part of the suez rift abstract detailed structural study of the eastern onshore part of the gharandal accommodation zone that separates the northern sw dipping and central ne dipping half grabens of the suez rift helped decipher the internal structure and deformation of accommodation zones of continental rifts this 60 km wide zone is affected by pure normal faulting the ne dipping faults of the northern half graben extend southward into the accommodation zone where they interfinger with sw dipping faults extending from the central half graben these two sets of rift parallel faults form several horsts and grabens in the accommodation zone areas dipping parallel to the northern or southern half grabens form several intermixing dip domains in the accommodation zone smaller scale accommodation of dip between these dip domains proceeds by the development of rift parallel folds twist zones in contrast to the southern accommodation zone of the suez rift the internal structure of the gharandal accommodation zone is believed to be representative of accommodation zones in regions a unaffected by prerift structures lying at high angles to the rift and b experiencing relatively small extension accommodation zones in areas having pre rift structures lying at high angle to the rift have relatively narrow width and are characterized by transverse strike slip faults strike slip movement on these faults is related to the torsional strain resulting from the opposite tilt directions and transport of fault blocks of adjacent half grabens

laser scanning and digital outcrop geology in the petroleum industry a review abstract the use of lidar light detection and ranging systems for modelling petroleum reservoir analogues has become increasingly popular over the past few years and there has been a proliferation of articles on the subject both on techniques and applications a review of the literature of recent years has been conducted focussing on the use of lidar data not only in petroleum geology related projects but also looking to the wider field of lidar usage to examine what other approaches may be of use to the petroleum geologist benefits of digital data acquisition are considered as well as a basic overview of data collection approaches use of a variety of attributes intensity colour dip azimuth co linearity co planarity among others is discussed as an aid to both manual and automated interpretation approaches integration of lidar data with other data types from traditional field data sedimentary logs for example and other digital data types such as multispectral and hyperspectral imagery and ground penetrating radar are discussed as a way of increasing the amount of information in the digital dataset the application of artificial intelligence approaches such as smart swarms and neural networks are considered as well as current developments in both hardware and software a variety of examples are given where lidar has been used in an innovative or interesting way showing the strength of this data acquisition approach when combined with appropriate interpretation and modelling techniques

is an unusual large enhancement of ionospheric electron density linked with the 2008 great wenchuan earthquake 1 on 12 may 2008 at 0628 ut a major earthquake ms 8 0 struck wenchuan county 31 0 n 103 4 e in southwest china the maximum ionospheric electron density at f2 peak nmf2 recorded an unusual large enhancement during the afternoon sunset sector by the chinese ionosondes over wuhan 30 5 n 114 4 e and xiamen 24 4 n 123 9 e which are close to the earthquake epicenter an averaged increase at these two stations is about 2 times on a geomagnetic quiet day 9 may kp 2 3 days prior to the earthquake relative to the median value of 1 12 may whereas the increase was much less significant over yamagawa 31 2 n 130 6 e and okinawa 26 7 n 128 2 e in japan combining the data from the network of 58 global positioning system receivers around china and the global ionospheric map the variations of the total electron content reveal the region where enhancement persisted for a long period to be within longitudes 90 130 e our results suggest that this abnormal enhancement is most possibly a seismo ionospheric signature

digital outcrop models applications of terrestrial scanning lidar technology in stratigraphic modeling abstract laser ranging is extremely accurate and efficient terrestrial scanning lidar light detection and ranging applied to outcrop stratigraphic mapping enables researchers to capture laser range data at a rate of thousands of individual x y z and laser intensity points per second these data in conjunction with complementary remotely and directly sampled data are used to conduct high precision facies characterization and to construct 3d geological computer models outcrop data are presented here to explain our workflow and to discuss the construction of rock based 3d digital outcrop models doms reproducibility and quantification are the drivers of this methodology high resolution terrestrial lidar acquisition processing interpretation and visualization are discussed and applied to mapping of geological surfaces in three dimensions laser generated models offer scientists an unprecedented visualization medium in a quantitative 3d arena applications of this technology include constructing and visualizing complex 3d earth models from outcrops for improved reservoir modeling flow simulation in hydrocarbon and aquifer systems and property modeling to constrain forward seismic modeling

gradual reduction in ionospheric f 2 region before the 2013 lushan earthquake contributed to the forthcoming earthquake or solar activity ionospheric anomalies before earthquakes during geomagnetic quiet conditions have been extensively discussed due to the importance of earthquake prediction however because of the high variability of ionosphere a real caution should be adopted before attributing the observations to seismo ionospheric precursors sips in an investigation of contradictory results in ionospheric variation before 2013 lushan earthquake we examine the ionospheric variation versus solar activity in order to assess the influence of solar activity of 27 day periodicity on ionospheric variation a quadratic regression model is developed by using the data of f2 layer critical frequency fof2 in april of 2008 2014 using the model ionospheric variation before the 2013 lushan earthquake is analyzed the results show that fof2 was strongly correlated with solar activity index f10 7 and had a low correlation with the remaining by eliminating the contribution of solar radiation which indicates that the gradual reduction in fof2 before the earthquake was contributed to the variation of solar radiation rather than the forthcoming earthquake

influence of mechanical stratigraphy on folding vs faulting abstract the competing processes of folding and faulting during shortening of a layered sequence are investigated using elastic plastic models in order to determine the influence of mechanical stratigraphy on the development of fold belts vs thrust belts the models consist of a strong middle layer and weaker decollement and cover layers the mechanical behaviour of each layer is determined by its plastic hardening modulus h and its elastic shear modulus g with bonded contacts fold amplification at low shortening strain relatively large h is greatest for a thin cover layer and a thick decollement layer at higher shortening strain h g the middle layer may reach its peak strength before the other layers causing it to become relatively weaker in shortening and causing fold amplification to be greatest for a thick middle layer free slip contacts between the layers enhance folding and fold amplification is greatest if the slip surfaces are roughly equally distributed throughout the sequence a relatively weak decollement layer enhances folding consistent with the fact that fold belts usually include a salt decollement layer dominant wavelengths increase with increasing strength contrasts between the layers and with increasing thicknesses of the decollement and strong layers

beryllium 7 and lead 210 in the atmosphere and surface snow over the greenland ice sheet in the summer of 1989 the concentrations of 7be and 210pb were measured in surface air and fresh and aging snow samples from summit 72 20 n 38 45 w and dye 3 65 10 n 44 45 w greenland during june and july 1989 the aerosol concentrations of these radionuclides showed rapid variations at both sites but were nearly twice as high on average at summit concentrations in the 16 fresh snowfall events that were sampled also showed wide variability but the averages were the same at the two sites the apparent difference in air snow fractionation and the lack of coherence in the concentration in air time series between the two sites indicate previously unsuspected complexity in atmospheric dynamics over the ice sheet improved understanding of atmospheric processes and how the results of those processes are recorded in snow and ice is crucial for full interpretation of the information about past atmospheric chemistry and climate contained in the snow and ice of glaciers around the world

seismo ionospheric signatures prior to m 6 0 taiwan earthquakes this paper examines variations of the greatest plasma frequency in the ionosphere fof2 recorded by the chung li ionosonde 25 0 n 121 1 e before m 6 0 earthquakes during 1994 1999 the 15 day running median and the associated inter quartile range are utilized as the reference and the upper or lower bounds to monitor the ionospheric fof2 variations for finding seismo ionospheric signatures precursors of the earthquakes it is found that precursors in the form of the recorded fof2 falling below its associated lower bound around 1200 1700 lt appear 1 6 days prior to these earthquakes on september 20 1999 ut september 21 taiwan local time a large mw 7 7 earthquake struck central taiwan near the small town of chi chi we analyzed the fof2 and found three clear precursors 1 3 and 4 days prior to the chi chi earthquake

style and sequence of deformation during extensional fault propagation folding examples from the hammam faraun and el qaa fault blocks suez rift egypt kilometre scale fault parallel folds are identified adjacent to normal faults in the oligo miocene suez rift egypt and are interpreted to have formed in response to fault propagation folding above upward propagating blind faults the geometry scale and distribution of secondary structures within the folds and their cross cutting relationships with the master faults allow the style and sequence of deformation during fault propagation folding to be established and suggest that during the initial stages of folding the proto footwall underwent extension which was accommodated by layer parallel slip in encasing mudstone horizons and linked normal faulting and block rotation in carbonate and sandstone units the proto hanging wall also contains dominantly extensional normal faults although locally where the master fault had a convex into the footwall map view trace reverse faulting and fracturing occurred secondary structures adjacent to the master fault were not all active simultaneously but initiated and died at different stages during the evolution of the fault propagation fold the results of this study confirm many key predictions of numerical and physical analogue models but also highlight several important controls on the evolution of fault propagation folds in extensional settings which existing models cannot capture such as the influence of the map view trace of the propagating fault and lateral variations in cover stratigraphy lithology and strength on the style and magnitude of secondary deformation

extensional fault related folding northwestern red sea egypt the duwi and hamadat areas on the northwestern margin of the red sea rift system exhibit superb outcrop examples of kilometric scale extensional fault related folds in this area the nakheil and hamadat faults of the rift border fault system consist of a series of wnw and nw trending segments that link through breached relay ramps the fault hanging walls are characterised by a series of offset synclines with non linear axial traces sub parallel to the faults the synclines are doubly plunging and in the immediate hanging wall to the normal faults the strata dip sub parallel to the fault these folds result from along strike displacement variations on the individual fault segments together with extension related fault propagation folding as the faults propagated upwards through a highly anisotropic pre rift sedimentary section in the duwi area the axial traces of the synclines are offset and bend in the regions of relay ramps in the hamadat area the synclines associated with individual fault segments are separated by transverse hanging wall anticlines that formed where segment linkage occurred numerical simulations of extension related fault propagation folding using a trishear model produce geometries that closely match those of the duwi and hamadat folds the dimensions of these hanging wall synclines and their relationships to fault displacement variations indicate that they are formed by extensional fault propagation folding rather than by frictional drag along the fault surface

early evolution of an extensional monocline by a propagating normal fault 3d analysis from combined field study and numerical modeling abstract the nopolo structure is located along the eastern margin of the baja california peninsula and formed during the early stages 12 6 ma of development of the gulf of california the nopolo structure is an 15 km long series of two nw striking extensional monoclines produced by the upward propagation of normal faults where normal faults reach the surface the footwall contains undisturbed gently dipping strata whereas the hanging wall is a highly deformed zone that contains fractured and faulted steep to subvertical strata long narrow grabens with moderate to steep east dipping strata are present in the hanging wall of the main normal faults initial monoclinal folding over blind normal faults produced a minimum of 300 m of structural relief once the faults propagated to the surface they offset the monoclines 20 30 m before faulting ceased we use an elastic dislocation model to invert fault geometry from bedding orientations around the nopolo structure the data are best matched by a listric normal fault that soles out at 5 km depth the model suggests that the tip line of the fault was located 1 km below the surface prior to the breaching of the monocline because the offset along the main normal faults is minimal 20 m the nopolo structure is a unique example of an extensional faulted monocline and monocline system where faulting ended soon after the monoclines were breached and offset

meteorological overview of the arctic boundary layer expedition able 3a flight series a meteorological overview of the arctic boundary layer expedition able 3a flight series is presented synoptic analyses of mid tropospheric circulation patterns are combined with isentropic back trajectory calculations to describe the long range 400 3000 km atmospheric transport mechanisms and pathways of air masses to the arctic and sub arctic regions of north america during july and august 1988 siberia and the northern pacific ocean were found to be the two most likely source areas for 3 day transport to the study areas in alaska transport to the barrow region was frequently influenced by polar vortices and associated short wave troughs over the arctic ocean while the bethel area was most often affected by lows migrating across the bering sea and the gulf of alaska as well as ridges of high pressure which built into interior alaska july 1988 was warmer and dryer than normal over much of alaska as a result the 1988 alaska fire season was one of the most active of the past decade airborne lidar measurements verified the presence of biomass burning plumes on many flights often trapped in thin subsidence layer temperature inversions several cases of stratosphere troposphere exchange were noted based upon potential vorticity analyses and aircraft lidar data especially in the barrow region and during transit flights to and from alaska

normal fault growth displacement localisation and the evolution of normal fault populations the hammam faraun fault block suez rift egypt abstract fault segment linkage migration of the locus of fault activity and displacement localisation were important processes controlling the late oligocene recent evolution of the normal fault population of the hammam faraun fault block suez rift initial fault activity was distributed across the fault block on fault segments that had attained their final length within 1 2 my of rifting these initial segments then either grew by increasing displacement and linked to form longer segmented fault zones or died during a rift initiation phase that lasted 6 8 my following this rift initiation phase displacement became localised onto 25 km long border fault zones bounding the fault block and many of the early high displacement intra block fault zones died following displacement localisation onto the major faults bounding the fault block the locus of maximum displacement continued to migrate with post middle miocene displacement focused on the western margin of the fault block this migration of fault activity between major crustal scale normal faults can be viewed in terms of strain localisation at the rift scale the results from this study question conventional fault growth models based on final displacement distributions and highlight the sequential nature of faulting on major normal faults bounding domino style tilted fault blocks

the structure and evolution of lower stratospheric frontal zones part 1 examples in northwesterly and southwesterly flow the structure evolution and dynamics of two lower stratospheric frontal zones are examined from a basic state variables perspective the case studies highlight the asynchronous evolution of the lower stratospheric and upper tropospheric frontal portions of upper level jet front uljf systems as well as some substantial differences in lower stratospheric frontal development that occur in southwesterly and northwesterly flow the evolution of the uljf in northwesterly flow was characterized by an initially intense but weakening lower stratospheric front along with an initially weak but intensifying upper tropospheric front throughout the evolution geostrophic cold air advection in cyclonic shear characterized a substantial portion of the lower stratospheric front this circumstance supported subsidence through the local jet core within the cold upper troposphere weakening the lower stratospheric front via tilting this subsidence extended downward below the jet core where it is suggested to have played a role in the early stages of upper tropospheric frontogenesis in the southwesterly flow case the evolution of the uljf was characterized by a strengthening lower stratospheric front and a weakening upper tropospheric front a deep column of upward vertical motion resulted from the superposition of lower tropospheric ascent associated with convection along a surface cold front and upper tropospheric lower stratospheric utls ascent through the jet core coincident with geostrophic warm air advection in cyclonic shear along large sections of the lower stratospheric front the utls ascent located on the cold edge of the lower stratospheric baroclinicity served to intensify the lower stratospheric frontal zone via tilting the implications of these lower stratospheric frontal processes on the topography of the tropopause and downstream sensible weather are discussed copyright 2012 royal meteorological society

the arctic frontal zone as seen in the ncep ncar reanalysis abstract calculations of a thermal front parameter using ncep ncar reanalysis data over the period 1979 98 reveal a relative maximum in frontal frequencies during summer along northern eurasia from about 60 to 70 n best expressed over the eastern half of the continent a similar relative maximum is found over alaska which is present year round although best expressed in summer these high latitude features can be clearly distinguished from the polar frontal zone in the midlatitudes of the pacific basin and collectively resemble the summertime arctic frontal zone discussed in several early studies while some separation between high and midlatitude frontal activity is observed in all seasons the summer season is distinguished by the development of an attendant mean baroclinic zone aligned roughly along the arctic ocean coastline and associated wind maxima in the upper troposphere the regions of maximum summer frontal frequency correspond to preferred areas of cyclogenesis and to where the summertime

experimental models of extensional forced folds we have used single layer and multilayer clay models to study the development of forced folds above normal faults our modeling results show that the deformation patterns associated with extensional forced folding depend on the dip of the underlying normal fault and the presence of layer parallel detachments in single layer clay models extensional forced folds are upward widening monoclines anticlinal axial surfaces dip in the same direction as underlying master normal faults and synclinal axial surfaces dip in the opposite direction of master normal faults most secondary faults are upward steepening normal faults if master normal faults are steeply dipping however many secondary normal faults become high angle reverse faults at shallow depths the propagation and linkage of secondary faults into through going normal faults terminates the development of extensional forced folds more folding occurs prior to fault linkage if the master normal fault is steeply dipping rather than gently dipping most dipping beds and secondary faults are preserved in the hanging walls of the through oing normal faults in multilayer clay models with layer parallel detachments extensional forced folds are also upward widening monoclines slip on the lowest detachment laterally transfers extension induced by normal faulting and forced folding from the master normal fault to the detachment edge slip on overlying detachments accommodates minor thickness changes associated with upward widening of the fold secondary faults include low angle normal faults near the anticlinal axial surface minor thrust faults near the synclinal axial surface and high angle normal faults above the detachment edge the model predicted deformation patterns are similar to those of extensional forced folds from the gulf of suez and offshore norway this similarity suggests that our modeling results apply to extensional forced folds and can provide guidelines for interpreting field well and seismic data

geometrical analysis of the refraction and segmentation of normal faults in periodically layered sequences normal faults contained in multilayers are often characterised by dip refraction which is generally attributed to differences in the mechanical properties of the layers sometimes leading to different modes of fracture because existing theoretical and numerical schemes are not yet capable of predicting the 3d geometries of normal faults through inclined multilayer sequences a simple geometric model is developed which predicts that such faults should show either strike refraction or fault segmentation or both from a purely geometrical point of view a continuous refracting normal fault will exhibit strike i e map view refraction in different lithologies if the intersection lineation of fault and bedding is inclined an alternative outcome of dip refraction in inclined multilayers is the formation of segmented faults exhibiting en echelon geometry the degree of fault segmentation should increase with increasing dip of bedding and a higher degree of segmentation is expected in less abundant lithologies strike changes and associated fault segmentation predicted by our geometrical model are tested using experimental analogue modelling the modelling reveals that normal faults refracting from pure dip slip predefined faults into an overlying sand cover will as predicted exhibit systematically stepping segments if the base of the cover is inclined

the influence of structural lithic units in fault related folds seminoe mountains wyoming u s a abstract analysis of basement involved folds in the seminoe mountains south central wyoming reveals that lithological contrasts within the sedimentary section created a mechanical anisotropy that influenced both fault geometry and the relative rates of fault propagation and fault slip two structural lithic units are identified a competent lower unit and an overlying incompetent unit the upper unit is made up of moderate ductility rocks that were thinned ahead of the hurt creek fault offset formations in the upper unit have small relative stretch r values and are interpreted to have represented an impediment to fault growth in contrast fault propagation was rapid relative to fault slip in the competent rocks of the lower structural lithic unit which have a correspondingly higher relative stretch the black canyon fault is oriented at a low angle to bedding in the lower structural lithic unit and is layer parallel near the base of the upper unit the red spring fault is a thin skinned thrust fault and is interpreted to be linked to the black canyon fault to generate a triangle zone geometry similar structures can be identified elsewhere in the rocky mountain foreland and this configuration may represent a previously unrecognized indicator of low angle basement faults changes in the deformation style between structural lithic units must be reflected in changing fold form thus preventing the direct application of geometric and kinematic models that predict a uniform fold profile