south indian countercurrent and associated fronts a striking feature of the south indian ocean circulation is the presence of the eastward south indian countercurrent sicc that flows in a direction opposite to that predicted by the classical theories of wind driven circulation several authors suggest that the sicc resembles the subtropical countercurrents stccs observed in other oceans which are defined as narrow eastward jets on the equatorward side of subtropical gyres where the depth integrated flow is westward these jets are associated with subsurface thermal fronts at thermocline depths by the thermal wind relation however the subsurface thermal front associated with the sicc has not been described to date other studies conjecture an important role for salinity in controlling the sicc in the present work we analyze three argo based atlases and data from six hydrographic cruises to investigate whether the sicc is accompanied by permanent thermal and density fronts including salinity effects the seasonal cycle of these fronts in relation to the sicc strength is also investigated we find that the sicc is better described as composed of three distinct jets which we name the northern central and southern sicc we find that the southern sicc around 26 s has an associated thermal front at subsurface depths around 100 200 m with salinity being of secondary importance the southern branch strength is related to mode waters poleward of the front similar to a stcc like current however the sicc multiple jet structure seems to be better described as resulting from pv staircases

two dimensional strain determination by the inverse surfor wheel abstract a simple method of two dimensional strain determination from the preferred orientation of deformed lines is presented it is based on the change of probability of intersecting lines on a given traverse as a function of traverse orientation the method can be applied to real lines such as grain boundary outlines or to virtual lines such as the tie lines between centre points of neighbouring grains in this manner estimates for the strain of surfaces i e of the particles enclosed by the surfaces and of bulk strain can be obtained

a climatic trigger for the giant troll pockmark field in the northern north sea abstract pockmarks are seafloor craters usually formed during methane release on continental margins however the mechanisms behind their formation and dynamics remain elusive here we report detailed investigations on one of the world s largest pockmark fields located in the troll region in the northern north sea seafloor investigations show that 7000 pockmarks are present in a 600 km2 area a similar density of pockmarks is likely present over a 15 000 km2 region outside our study area based on extensive monitoring coring geophysical and geochemical analyses no indications of active gas seepage were found still geochemical data from carbonate blocks collected from these pockmarks indicate a methanogenic origin linked to gas hydrate dissociation and past fluid venting at the seafloor we have dated the carbonates using the u th method in order to constrain the pockmark formation the carbonates gave an isochron age of 9 59 1 38 ka i e belonging to the initial holocene moreover radiocarbon dating of microfossils in the sediments inside the pockmarks is consistent with the ages derived from the carbonates based on pressure and temperature modelling we show that the last deglaciation could have triggered dissociation of gas hydrates present in the region of the northern part of the norwegian channel causing degassing of 0 26 mtch4 km2 at the seafloor our results stress the importance of external climatic forcing of the dynamics of the seafloor and the role of the rapid warming following the younger dryas in pacing the marine gas hydrate reservoir

production of hypersaline pools in shallow basins by evaporation 1 this paper incorporates a correction to the heat balance equation in the general ocean models by properly quantifying the sun s light that penetrates the ocean surface and reaches the bottom part of the light that hits the bottom in shallow pools of water gets absorbed depending on the albedo of the bottom and is reradiated as heat thus warming up the waters there significantly the light that is not absorbed gets reflected back up and a part of it is absorbed by the water constituents on its way up while the remaining light leaves the water surface it was found from our simulations that the temperatures attained by shallow pools depend upon the water depth and bottom albedo increased evaporation associated with such shallow water warming leads to the formation of hypersaline waters this natural salination is found to occur in the shallow basin near the andros island in the bahamas where the waters are less than 7 m deep the maximum salinity of these waters is as high as 46 psu in summer these hypersaline waters being denser than the nearby deep ocean advect down to depths of 50 m in summer and 75 m in winter

regional variations in the influence of mesoscale eddies on near surface chlorophyll eddies can influence biogeochemical cycles through a variety of mechanisms including the excitation of vertical velocities and the horizontal advection of nutrients and ecosystems both around the eddy periphery by rotational currents and by the trapping of fluid and subsequent transport by the eddy in this study we present an analysis of the influence of mesoscale ocean eddies on near surface chlorophyll chl estimated from satellite measurements of ocean color the influences of horizontal advection trapping and upwelling downwelling on chl are analyzed in an eddy centric frame of reference by collocating satellite observations to eddy interiors as defined by their sea surface height signatures the influence of mesoscale eddies on chl varies regionally in most boundary current regions cyclonic eddies exhibit positive chl anomalies and anticyclonic eddies contain negative chl anomalies in the interior of the south indian ocean however the opposite occurs the various mechanisms by which eddies can influence phytoplankton communities are summarized and regions where the observed chl response to eddies is consistent with one or more of the mechanisms are discussed this study does not attempt to link the observed regional variability definitively to any particular mechanism but provides a global overview of how eddies influence chl anomalies

new seismotectonic data from an intraplate region focal mechanisms in the armorican massif northwestern france summary focal mechanism solutions are determined for 11 small intraplate earthquakes that occurred between 1990 and 1998 in normandy and the channel islands these mechanisms are obtained from the p wave first motion polarities recorded by stations from local and regional seismic networks the accuracy of each hypocentral location is closely examined and the quality of each fault plane solution is discussed by considering the influence of the velocity structure the predominant feature of the computed focal mechanisms is the relatively widespread near horizontal ne sw t axis orientation horizontal p axes strike roughly nw se mechanism solutions for the earthquakes in the avranches region show left lateral strike slip on a nnw sse fault zone for the overall region it seems that nodal planes of normal faulting solutions trend nw se or wnw ese whereas those of thrust faulting solutions trend ne sw this is in agreement with the general regional stress pattern the ne sw normal fault plane solution of the 1990 jersey event is unique because it is not consistent with the regional style of faulting

the structural evolution of the english channel area the structural evolution of the english channel area is controlled by structure and particularly by the pre existing cadomian and variscan crustal discontinuities which have been reactivated repeatedly in post variscan times they controlled the crustal subsidence that produced basin development in the mesozoic prior to the sea floor spreading in the north atlantic region they were then reactivated during the cenozoic compression and basin inversion the english channel development is ascribed to mid tertiary differential uplift oligocene to miocene during late tertiary to quaternary times the channel displays characteristics of a tectonically controlled fluvial basin periodically invaded by the sea at the lithospheric scale the channel can be considered as an active intraplate area influenced by the nw se alpine push the nw se atlantic ridge push and glacial rebound stresses copyright 2003 john wiley sons ltd

the origin of bahamian whitings revisited two schools of thought exist regarding the origin of the aragonite needles which make up the milky patches of water prominent on the bahama banks one school views these so called whitings as spontaneous precipitates cloud 1962 shinn et al 1989 robbins et al 1997 and the other views them as stirred up bottom sediment broecker and takahashi 1966 morse et al 1984 in the paragraphs which follow we summarize what we consider to be iron clad radiocarbon and chemical evidence that whitings are dominated by re suspended sediment we offer a new and highly speculative mechanism for this re suspension black tipped sharks which inhabit whitings purposefully stir up the sediment in order to create a trap for fish much as spiders construct webs as traps for insect prey

structural control of igneous complexes and kimberlites a new statistical method abstract the spatial distribution of magmatic activity may provide important information about magma formation magma transport through the lithosphere and the mechanical properties of the lithosphere zones of weakness in the crust tentatively associated with deep crustal fractures have been hypothesized to control the locations of magmatic centers a connection between some lineaments and large scale crustal structures suggests that magma emplacement could be controlled by sets of fractures with linear outcrop patterns in this case the locations of magmatic centers would not be distributed randomly but would have an anisotropic component thus identification and characterization of such anisotropic control is a valuable exercise previous attempts to derive information about anisotropies from the locations of magmatic centers have been flawed or have provided only an estimate of the directions of anisotropy in this paper we extend concepts presented previously lutz 1986 to derive estimates of the locations as well as the trends of the features that could control magmatism monte carlo simulations of random point patterns are used to provide a null model relative to which the characteristics of actual patterns can be evaluated on a statistical basis tests on simulated anisotropic patterns show that the method can successfully reveal underlying anisotropies even if a substantial proportion of the magmatic centers are located randomly applications to central magmatic complexes in nigeria and to kimberlites in south africa reveal control by anisotropies in both areas however the trends and locations are not apparently related to prominent geologic features previously suggested to have played a role thus the anisotropies are imposed either by structures at depth or by structures that appear at the surface as minor fractures and joints shallow igneous complexes are often associated with potentially valuable economic deposits therefore this method provides a means to predict the locations of resources however the method can be applied to the analysis of anisotropy in any features that can be approximated by points lying within a plane thus earthquake epicenters might be analyzed to determine locations to be avoided to reduce seismic risk

improved relative locations of clustered earthquakes using constrained multiple event location a new method for improving relative locations of clustered earthquakes is presented and applied to a suite of microearthquakes induced by hydraulic fracturing the method is based on the assumption that clustering of earthquake hypocenters is obscured by the uncorrelated scatter of individual hypocenters the method is implemented as an additional constraint in a joint hypocenter determination jhd scheme the method shifts event hypocenters toward the center of mass of the events within some volume surrounding the event location if the rms misfit between predicted and measured arrival times does not increase significantly the method uses the same basic assumption of jones and stewart 1997 which is that there is greater clustering in actual earthquake locations than there is in locations determined using conventional techniques our method differs in that it is implemented as part of the jhd process so it operates on raw travel time data rather than on derived hypocenters the method produces hypocenters from a demonstration field dataset that are similar to those obtained by phillips et al 1997 from time consuming precise manual repicking of relative arrival times of events the clustering constraint can easily be incorporated as an additional constraint in earthquake location velocity tomography codes and may lead to improved velocity structure determination and earthquake location pattern identification and interpretation

source parameters of the 1926 and 1927 jersey earthquakes from historical instrumental and macroseismic data abstract english channel islands are located off normandy coast of france within an intraplate area not associated with high seismicity rate and active tectonics however in july 1926 a damaging and well documented earthquake occurred there followed by a strongly felt event in february 1927 in this paper we reprocess macroseismic observations analog seismograms and bulletin data in order to re appraise the location and magnitude of these two earthquakes we find that the macroseismic epicentre of the 1926 jersey earthquake is shifted to the east when compared with the location offshore south of jersey given in both the french database sisfrance and the recent french catalog fcat 17 arrival times from published data together with our own onset time readings are processed in order to obtain probabilistic hypocentral locations the maximum likelihood instrumental epicentre of the 1926 event is located about 15 km east of jersey island 49 20 n 1 82 w this epicentre is well constrained within a 10 km radius area the location of the 1927 epicentre is slightly south of jersey at a location similar to that of sisfrance but this latter epicentre is less constrained as fewer observations are available the probability density function for the 1927 epicentre is relatively diluted focal depth remains very poorly determined for both the 1926 and 1927 events analysis of historical seismograms is also performed in order to determine both surface wave and moment magnitudes ms and mw we find ms 5 6 0 2 for the 1926 event and ms 5 0 for the 1927 event waveform fitting of some of the highest quality seismograms of the 1926 event gives us mw in the range 5 0 5 5 depending on the chosen focal depth and focal mechanism the 1927 jersey earthquake is expected with an intensity magnitude mi about 0 6 smaller

satellite observations of mesoscale eddy induced ekman pumping abstractthree mechanisms for self induced ekman pumping in the interiors of mesoscale ocean eddies are investigated the first arises from the surface stress that occurs because of differences between surface wind and ocean velocities resulting in ekman upwelling and downwelling in the cores of anticyclones and cyclones respectively the second mechanism arises from the interaction of the surface stress with the surface current vorticity gradient resulting in dipoles of ekman upwelling and downwelling the third mechanism arises from eddy induced spatial variability of sea surface temperature sst which generates a curl of the stress and therefore ekman pumping in regions of crosswind sst gradients the spatial structures and relative magnitudes of the three contributions to eddy induced ekman pumping are investigated by collocating satellite based measurements of sst geostrophic velocity and surface winds to the interiors of eddies identified from their sea surface height signatures on average e

interannual to decadal variations of tropical subtropical exchange in the pacific ocean boundary versus interior pycnocline transports abstract interannual to decadal variations of tropical subtropical mass exchange in the pacific ocean are investigated using a near global ocean general circulation model along with satellite observations of sea level and wind and a data assimilation product the analysis focuses on the variability of pycnocline transports through the western boundary and interior near 10 n and 10 s in contrast to time mean exchange where boundary and interior pycnocline transports are both equatorward the variations of boundary and interior pycnocline transports are found to be generally anticorrelated to each other moreover the variation of the boundary pycnocline transport is smaller than that of the interior again different from time mean exchange where the boundary transport at 10 n is substantially larger than that through the interior interannual variations of the boundary and interior transports are consistent with near surface geostrophic flow inferred from sea level data interior pycnocline flow into th

intraplate seismicity new seismotectonic data in western europe abstract fault plane solutions for 128 earthquakes which occurred in france and neighbouring areas have been determined stress field information given by these data are discussed in relation to previous tectonic knowledge the western alps are characterized by a compressional regime with a fan shaped distribution of p axes which might be related to the interaction mechanism between europe and the adriatic plate the pyrenean region is mainly submitted to a south north compression tectonic activity in this area seems to be determined by the presence of two subduction zones with reverse dips in the south bay of biscay and in the central pyrenees the transition zone between these two active belts is characterized by significant seismicity with a transpression regime

interannual modulation of eddy kinetic energy in the southeast indian ocean by southern annular mode 1 interannual variability in the mesoscale eddy field over the southeast indian ocean of 15 s 35 s and 60 e 110 e is investigated on the basis of 16 year satellite altimetry observations eddy kinetic energy eke in this region appears stronger in 2000 2004 and weaker in 1993 1996 1998 2000 and 2007 it is found that this interannual modulation of eke is mediated by the southern annular mode sam with a positive negative sam corresponding to weak strong eddy activity in this region the interannual modulation of the eke by the sam is through modulating the baroclinic instability associated with the surface intensified south indian countercurrent sicc and the underlying south equator current sec system in the positive phase of the sam the southeastern subtropical indian ocean is dominated by an anomalous ekman upwelling which slackens the southward tilt of the isotherms and thus reduces the sicc this shall reduce the vertical velocity shear of the sicc sec current system leading to a weak instability and thus a weak eddy activity

dense saline plumes in exuma sound bahamas cold dense plumes have been associated with coral killoff on tropical shelves as well as with sediment movement from banks to the deep basins adjacent to shallow banks this paper presents evidence that plumes of dense salty water generated over shallow banks entrain ambient water rather than descending intact to a density compensation level as has sometimes been assumed and that plumes can spread laterally distances of tens of kilometers from their source in exuma sound dense salty water appears to be formed year round by cooling or by evaporation over shallow banks the water is forced by tidal currents through the channels between islands onto the narrow shelves of exuma sound where it likely moves as gravity currents the gravity currents entrain basin water as they cross the shelf and cascade over the steep shelf edge into exuma sound after which they are advected by ambient currents around the sound a numerical streamtube model was used to explore early details of plume evolution the model predicts that the plumes entrain 2 6 5 0 parts ambient water particularly as they traverse the gently sloping shelf the resulting loss of density contrast means that the model plumes reach their density level in exuma sound at relatively shallow depths 50 95 m just below the base of the mixed layer the final depth of modeled plumes is relatively consistent with observed plume depths which vary seasonally 75 m in early winter to 45 m in summer depending on the depth and density characteristics of the seasonal mixed layer over the sound observed plume thickness ranges from 40 m in winter to 20 30 m in summer final salinity values exceed 36 8 practical salinity units final density ranges from sigmat 23 75 to 24 5 plume depth vertical structure and longevity are shown to depend on upper ocean mixing processes such as convection and wind mixing

a point pattern analysis of the distribution of earthquakes in normandy france abstract a new mathematical method has been developed to guide the interpretation of sparse epicenter distributions the aim of the technique is the assessment of the significance of epicenter alignments this assessment is connected to the detection of seismic faults the method has been tested on synthetic data sets and on seismicity from the san francisco bay area these tests show high detection capabilities when the method is applied to actual data in order to discard artificial lines the interpreter must check the results using geological information the method is applied to epicenters in western normandy the main structural directions of normandy are tracked by sparse epicenters

satellite observations of chlorophyll phytoplankton biomass and ekman pumping in nonlinear mesoscale eddies nonlinear mesoscale eddies can influence biogeochemical cycles in the upper ocean through vertical and horizontal advection of nutrients and marine organisms the relative importance of these two processes depends on the polarity of an eddy cyclones versus anticyclones and the initial biological conditions of the fluid trapped in the core of the eddy at the time of formation eddies originating in the eastern south indian ocean are unique in that anticyclones typically associated with downwelling contain elevated levels of chlorophyll a enhanced primary production and phytoplankton communities generally associated with nutrient replete environments from analysis of 9 years of concurrent satellite measurements of sea surface height chlorophyll phytoplankton carbon and surface stress we present observations that suggest eddy induced ekman upwelling as a mechanism that is at least partly responsible for sustaining positive phytoplankton anomalies in anticyclones of the south indian ocean the biological response to this eddyinduced ekman upwelling is evident only during the austral winter during the austral summer the biological response to eddy induced ekman pumping occurs deep in the euphotic zone beyond the reach of satellite observations of ocean color

dem and gis analysis of the stream gradient index to evaluate effects of tectonics the normandy intraplate area nw france computer based geomorphometry using a dem digital elevation model allows the analysis of the three dimensional properties of landscape this methodology is particularly useful in an intraplate region like western europe where the simple visual inspection of the topography cannot resolve the evolutionary trends of landforms in these domains the morphologies of the topographic surface may be controlled mainly by climate under a low rate of tectonic deformation among the geomorphometric parameters the stream length index sl has been used to characterize fluvial systems in relation to tectonics movements this work develops an algorithm to derive and map the sl index using a dem and gis to investigate its spatial variations in a broad area the algorithm is applied to a zone of weak intraplate deformation the coastal lowlands of normandy france the obtained spatial distributions of sl point to anomalous zones with high sl values these zones are adjacent to mapped fault scarps and characterized by changes in flow direction a kruskal wallis test shows that the bedrock lithology has no impact on the sl value therefore the sl variations can be related mainly to a differential uplift due to quaternary tectonic forcing quaternary sea level fluctuations may also be responsible for high sl values in a part of the coastal lowland

decadal phase change in large scale sea level and winds in the indo pacific region at the end of the 20th century 1 satellite observations of sea surface height ssh and wind stress for the period of 1993 2006 reveal a near coherent large scale decadal variability in much of the indo pacific region with a phase change at the turn of the 20th century trade wind variations in the tropical pacific and south indian ocean are anti correlated with each other as are ssh differences across these two basins implying anti correlated variation of the subtropical cells in the two oceans decadal changes in large scale ssh in the extra tropics are mostly associated with well defined patterns of wind stress curl indicating a near coherent decadal variation in the strength of subtropical and subpolar gyres together these variations reflect a linkage in the circulation of the pacific and indian oceans via atmospheric and oceanic bridges the phase change in the tropical pacific tends to occur earlier than elsewhere suggesting a potential role of the tropical pacific in regulating decadal variability of the entire region

evolution movement and decay of warm core leeuwin current eddies abstract characteristics of eddies originating in the leeuwin current lc have been investigated using 10 day sea level anomaly maps of combined topex poseidon and ers altimeter data for the period 1995 2000 during these 6 years 37 long lived anticyclonic eddies were tracked from the west coast of australian to 90 e between three and nine eddies were spawned each year and their trajectories are described in detail most long lived eddies are generated in may june when the lc is most intense and at three preferred locations 20 21 5 s 24 25 s and 28 31 s the temporal evolution and latitudinal variations of the sea level anomalies and their radius and drift speed are discussed topography plays an important role in the evolution and structure of the eddies interactions with topography can induce splitting or merging of eddies which further affects the eddy decay

a method for determining significant structures in a cloud of earthquakes the interpretation of a cloud of earthquake hypocenters in terms of causative structures is not a simple task locations are subject to uncertainties which will not be the same for every earthquake the data should therefore not be interpreted simply by inspection which is difficult in the case of three dimensional data anyway instead we propose using the location uncertainties as a guide in processing the data earthquake locations are moved inside their uncertainty or confidence ellipsoids until a simplified picture of the earthquake cloud is obtained which can then be interpreted in terms of some simplified structure such as faults the aim of the approach is to give the simplest possible structure that is consistent with all the location and confidence ellipsoid data the method is applied to three synthetic sets of data these illustrate the potential and limitations of the method application to a real earthquake data set from rabaul caldera in papua new guinea gives an image of the caldera ring fault that suggests departures from the simple ring fault structure previously assumed sensitivity analysis on the rabaul data shows that the method is not unduly sensitive to the assumptions that have to be made in applying it

a new approach for associating earthquakes with geological structures application to epicenters in southern illinois and southeastern missouri 1 a spatial statistical analysis method has been applied successfully on diffuse seismicity of southern illinois and southeastern missouri the study area is a region of diffuse deformation and seismicity close to the new madrid seismic zone the new madrid earthquake catalog is examined through the blade method applied on collapsed epicenters this is a new approach since the blade method is applied on improved locations through the best estimate method the blade method performs tests on binomial distributions for the detection of significant seismic alignments within a sparse epicenter distribution from the epicenters of the new madrid earthquake catalog using the blade method on collapsed epicenters it is statistically valid to state that seismicity is associated with the new madrid seismic zone and the black ellington salem and ste genevieve faults

signature of mesoscale eddies in satellite sea surface salinity data a persistent signature of coherent mesoscale eddies in sea surface salinity sss is revealed by analyzing the relationship between satellite sss and sea surface height ssh variability in an eddy following reference frame our analysis focuses on mid ocean eddies in two representative regions the southern indian ocean and the north atlantic subtropical gyre the resulting composite averages reveal a clear signature of mesoscale eddies in satellite sss with typical sss anomalies of 0 03 0 05 psu the spatial structure of eddy induced sss perturbations can be characterized as a superposition of a dipole structure arising from horizontal advection of the background sss gradient by eddy velocity field and a monopole structure related to the eddy core the observed relationships between sss and ssh anomalies are used to provide a regional assessment of the role of mesoscale eddies in the ocean freshwater transport in the north atlantic subtropical gyre this article is protected by copyright all rights reserved

active tectonics seismicity and geomorphology with special reference to normandy france integrated studies based on tectonic seismotectonic and geomorphological analyses indicate that normandy northwest france has been an active area during the quaternary topography and landform discontinuities reflect the dislocation and differential uplift of a late cenozoic platform the tectonic activity is represented by i active faults indicated by linear scarps and seismic activity ii offsetting of pre existing surfaces iii plio pleistocene sedimen tation restricted within narrow subsiding zones and iv morphometric properties of drainage basins that indicate zones of differential uplift the inferred strain pattern involves i a shortening direction that strikes nw se as expected in the european context of alpine compression and ii a ne sw trending extension accommodated by nw se normal faults the geomorphological systems encountered in normandy preferentially record differential vertical displacements copy right 2000 john wiley sons ltd

pattern and velocity of propagation of the global ocean eddy variability 1 satellite altimeter data are used to study the characteristics of the horizontal propagation of eddy variability of the global oceans decade long time series of sea surface height is analyzed for finding the maximum cross correlation with neighboring time series within a window of space and time lags the space and time lags corresponding to the maximum correlation allow an estimate of the propagation velocity of the eddy variability that dominates the variance of sea surface height anomalies the method cannot distinguish the various forms of eddy variability isolated eddies and fronts the meandering of ocean currents or planetary waves however the results provide at a given location of the global oceans a uniquely determined propagation velocity that represents a time averaged description of the tendency of the movement of the local eddy variability the propagation velocity is highly inhomogeneous in space outside the equatorial zone the zonal propagation is intrinsically westward modified by ocean currents which could reverse the zonal propagation to eastward in regions like the gulf stream and the antarctic circumpolar current at midlatitudes and high latitudes the propagation pattern is highly affected by the path of ocean currents and the shape of bottom topography at tropical latitudes the meridional propagation is convergent toward the equator in the western basins and divergent away from the equator in the eastern basins comparison with the simulations of an eddy permitting ocean general circulation model shows overall agreement especially in the latitudinal variation of the zonal propagation velocity the result suggests that the model has captured the essence of the dynamics governing the propagation of ocean eddy variability

modeling studies of the leeuwin current off western and southern australia the leeuwin current strengthens considerably from february to may each year following the slackening of southerly coastal winds strong eddies develop a high resolution multilevel primitive equation ocean model is used to examine this eddy development in an idealized way by considering the development of flow from rest when temperatures are initially given the observed longshore gradients the system is allowed to geostrophically adjust in the absence of longshore winds and of any surface heat flux two types of experiments are conducted the first type uses the indian ocean climatological temperature gradient forcing case 1 and 2 while the second type repeats the first experiment with the added contribution of the north west shelf nws temperature profile cases 3 and 4 to investigate the additional effects of coastline irregularities cases 1 and 3 use an ideal coastline while cases 2 and 4 use an irregular realistic coastline in all cases maximum surface velocities occur at cape leeuwin where the leeuwin current changes direction and off southern australia maximum undercurrent velocities occur off western australia in case 1 cape leeuwin and the western australian coast are the preferred locations for the development of warm anticyclonic eddies which are generated due to a mixed instability mechanism in case 2 the warm anticyclonic eddies occur in the vicinity of coastal promontories and at cape leeuwin while advection of warm water is present along the entire coast in case 1 the irregular coastline geometry limits the extent of warm water in case 2 the added contribution from the nws water in cases 3 and 4 augments the onshore geostrophic inflow to produce a model leeuwin current and undercurrent that are more vigorous and unstable than in the previous cases in case 3 the nws water adds strong horizontal shear to the coastal equatorial region of the domain and vertical shear to the inshore current it also advects warmer water along the entire coast in case 4 the addition of both the nws water and the irregular coastline results in the establishment of a stronger surface current and undercurrent than in the previous cases however the irregular coastline limits the extent of the advection of the nws warmer water along the australian coast in all cases warm anticyclonic eddies develop at the coast cold cyclonic eddies form from the limbs of the established warm anticyclonic eddies with the result that two counterrotating cells are developed once the eddy pairs begin their westward propagation the leeuwin current intensifies as nonlinear effects result in a jet between the eddies and the coast these effects translate downstream to augment the current velocities at the coast which due to a mixed instability mechanism result in the development of new anticyclonic eddies at the coast the results from case 4 which has the most realistic features highlights the major characteristics of the leeuwin current and agrees well with available observations these results show that the model successfully captures the qualitative nature of the nonlinear eddying response of the leeuwin current

wavelet transform a future of rock fabric analysis abstract although twenty years ago fabric was defined as the complete spatial and geometrical configuration of all those components that make up a deformed rock fabric was mainly synonymous with lattice preferred orientation very little attention has been paid to the multi scale geometrical and spatial relationships of the rock components fabric quantification in terms of size shape orientation and location at all scales is now performed in two dimensions using anisotropic wavelets as a first example the wavelets are applied to the famous colour plate of sander and the results compared to his axial distribution analysis applied to the k feldspars of a rock section from the sidobre granite pluton montagne noire france the wavelet analysis shows i alignment of grains resulting from mechanical interactions between grains and shows that shearing occurred within the crystalline frame ii preferred grain orientation the classical grain shape fabric parallel to the overall mineral lineation and iii small tensional domains elongate perpendicular to the lineation infilled by the residual melt just before total crystallisation attesting to the stretching nature of the mineral lineation the future of rock fabric analysis will come from new steps in understanding the processes acting during fabric development along with a further development of wavelet analysis using high resolution three dimensional fabric data

divergent pathways of cyclonic and anti cyclonic ocean eddies satellite altimetry is used to study the propagation pathways of warm and cold ocean eddies in different ocean basins we consider eddies that have a life span longer than 3 months and we present three regional studies in the southeast indian the southeast atlantic and the northeast pacific oceans the case studies show that simple theories for vortex propagation on a plane work in regions where energetic eddies propagate though a weak background flow under these conditions anticyclonic cyclonic eddies propagate westward and equatorward poleward this divergence in the eddy pathways implies a net equatorward eddy heat flux and has implications for the meridional transport of freshwater carbon nutrients etc

structural analysis of hypocentral distribution of an earthquake sequence using anisotropic wavelets method and application 1 spatial organization of earthquake sequences is investigated to localize active rupture planes and to reconstruct the geometry of the inferred rupture zone we have developed a new approach the normalized optimized anisotropic wavelet coefficient noawc method to extract from a set of hypocenters the active ruptures planes our approach permits the detection of organized structures within a plane regardless of its size location shape anisotropy and orientation it includes the determination of a system of three perpendicular sections minimizing the effects of projections of the hypocenters and intrinsically accounts for uncertainty in the location of the seismic events the accuracy and the effectiveness of the noawc procedure are illustrated on both synthetic and real data an application to the m 5 1 arudy french pyrenees aftershock sequence shows how a combination of the possible mathematically reconstructed geometries can be combined with the available fault plane solutions and geomorphological markers to determine the active rupture planes and to propose and validate a local tectonic model this new multitool approach lends itself to quantitative and computer assisted analyses of large data sets