fault reactivation control on normal fault growth an experimental study field studies frequently emphasize how fault reactivation is involved in the deformation of the upper crust however this phenomenon is generally neglected except in inversion models in analogue and numerical models performed to study fault network growth using sand silicon analogue models we show how pre existing discontinuities can control the geometry and evolution of a younger fault network the models show that the reactivation of pre existing discontinuities and their orientation control i the evolution of the main fault orientation distribution through time ii the geometry of relay fault zones iii the geometry of small scale faulting and iv the geometry and location of fault controlled basins and depocenters these results are in good agreement with natural fault networks observed in both the gulf of suez and lake tanganyika they demonstrate that heterogeneities such as pre existing faults should be included in models designed to understand the behavior and the tectonic evolution of sedimentary basins

release faults associated structures and their control on petroleum trends in the reconcavo rift northeast brazil release faults are rift cross faults which develop to accommodate the variable displacements of the hanging wall block along the strike of normal faults release faults are nearly perpendicular or obliquely oriented to the strike of the normal fault they are related to they have maximum throws adjacent to the parent normal fault and die out in the hanging wall away from it they form to release the bending stresses in the hanging wall and do not reflect the orientation of the regional stress field in a basin commonly they show normal oblique displacements and are preferentially located along the strike ramps release faults may also act at the scale of an entire basin reaching displacements of thousands of meters joints shale and salt diapirs may develop in association with release faults because all these structures represent domains of stress release they may work as conduits for oil migration and oil traps in extensional basins this is the case of the reconcavo basin in northeastern brazil a cretaceous failed rift connected to the eastern brazilian continental margin basins in the reconcavo basin two large scale release faults with displacements in the order of 3 km developed in the hanging wall of the rift border faults and control the location of the main oil fields

controls on early rift geometry new perspectives from the bilila mtakataka fault malawi we use the 110 km long bilila mtakataka fault in the amagmatic southern east african rift malawi to investigate the controls on early rift geometry at the scale of a major border fault morphological variations along the 14 8 m high scarp define six 10 40 km long segments which are either foliation parallel or oblique to both foliation and the current regional extension direction as the scarp is neither consistently parallel to foliation nor well oriented for the current regional extension direction we suggest the segmented surface expression is related to the local reactivation of well oriented weak shallow fabrics above a broadly continuous structure at depth using a geometrical model the geometry of the best fitting subsurface structure is consistent with the local strain field from recent seismicity in conclusion within this early rift pre existing weaknesses only locally control border fault geometry at subsurface

structural implications of strain localization towards a continental transform fault the example of the shift between the levant margin and the dead sea fault plate boundary abstract continental transform faults accommodate lateral motion between two adjacent plates often evidence for such motion is hard to detect due to onland processes of erosion investigation of a submerged passive continental margin adjacent to a transform plate boundary might provide indications for the developmental stages of the transform to examine this hypothesis we analyzed the messinian to recent stratigraphy and structure of the levant continental margin that resides ca 100 km from the dead sea fault dsf continental transform the analysis is based on interpretation of seismic reflection data 2d and 3d time migrated and pre stack 3d depth migrated and four boreholes it includes construction of structural maps tracking of stacking patterns and calculations of sedimentation rates data show that the levant margin developed through three phases 1 late miocene earliest zanclean 6 5 ma nne ssw left lateral strike slip faulting 2 zanclean late gelasian 5 1 8 ma syn depositional folding striking in the same direction the top gelasian surface marks an abrupt change which is expressed as 3 mass slumping that occurred due to regional basinward tilt continuation of differential subsidence is manifested by calabrian to recent progradation 1 8 0 ma while nile sediment flux peaked at 1 8 ma and decreased during the calabrian to recent our data shows an increase in sedimentation on the levant margin throughout the entire plio pleistocene this discrepancy is caused by the regional tilting of phase 3 which shifted the depocenter to the west correlations to onshore findings suggest that the faulting folding and tilting observed on the continental margin represent localization of strain towards the dsf during the pliocene gelasian 5 3 1 8 ma this is attributed to the consequent deepening of the dsf and the incipient collision of the eratosthenes seamount with the cyprus arc the continental margin records the development of the nearby active transform through structural and sedimentary modifications

lateral interaction between metamorphic core complexes and less extended tilt block domains the alpujarras strike slip transfer fault zone betics se spain abstract the alpujarras area in southeastern spain exhibits one of the scant documented examples of extension related strike slip faults bordering core complexes in the world faults of the alpujarras fault zone define a regional scale complex ene striking transfer zone that marks the boundary among the sierra nevada elongated dome a highly extended constricted core complex and a less extended domain formed by large scale tilt blocks detailed mapping and structural analysis show that the alpujarras fault zone is an integral part of the wsw directed normal fault systems that thinned the betic hinterland during the middle miocene to recent time fault patterns and palaeostress analysis both indicate that dextral movement along the strike slip faults was induced by a local stress field with a sub horizontal e w to ese wnw trending maximum principal stress axis which is synchronous with the regional stress field driving the normal fault systems palaeostress analysis also indicates subsequent variations in the stress field with a sub horizontal nw se to n s trending maximum principal stress axis thus producing both the tectonic inversion of the northern fault of the alpujarras system and shortening of the unloaded extensional detachment footwall a simplified kinematic model for the tectonic evolution of the alpujarras area from the middle miocene to recent emphasizes the kinematic coupling of normal faults and strike slip transfer zones in the extensional process

statistical estimation of transmission loss from geoacoustic inversion using a towed array geoacoustic inversion estimates environmental parameters from measured acoustic fields e g received on a towed array the inversion results have some uncertainty due to noise in the data and modeling errors based on the posterior probability density of environmental parameters obtained from inversion a statistical estimation of transmission loss tl can be performed and a credibility level envelope or uncertainty band for the tl generated this uncertainty band accounts for the inherent variability of the environment not usually contained in sonar performance prediction model inputs the approach follows gerstoft et al ieee j ocean eng 31 299 307 2006 and is demonstrated with data obtained from the mapex2000 experiment conducted by the nato undersea research center using a towed array and a moored source in the mediterranean sea in november 2000 based on the geoacoustic inversion results the tl and its variability are estimated and compared with the measured tl

ranging bowhead whale calls in a shallow water dispersive waveguide this paper presents the performance of three methods for estimating the range of broadband 50 500 hz bowhead whale calls in a nominally 55 m deep waveguide conventional mode filtering cmf synthetic time reversal str and triangulation the first two methods use a linear vertical array to exploit dispersive propagation effects in the underwater sound channel the triangulation technique used here while requiring no knowledge about the propagation environment relies on a distributed array of directional autonomous seafloor acoustics recorders dasars arranged in triangular grid with 7 km spacing this study uses simulations and acoustic data collected in 2010 from coastal waters near kaktovik alaska at that time a 12 element vertical array spanning the bottom 63 of the water column was deployed alongside a distributed array of seven dasars the estimated call location to array ranges determined from cmf and str are compared with dasar triangulation results for 19 whale calls the vertical array ranging results are generally within 10 of the dasar results with the str results providing slightly better agreement the results also indicate that the vertical array can range calls over larger ranges and with greater precision than the particular distributed array discussed here whenever the call locations are beyond the distributed array boundaries

world wide delivery of river sediment to the oceans new data and new estimates from old data show that rivers with large sediment loads annual discharges greater than about 15 times 10 6 tons contribute about 7 times 10 9 tons of suspended sediment to the ocean yearly extrapolating available data for all drainage basins the total suspended sediment delivered by all rivers to the oceans is about 13 5 times 10 9 tons annually bedload and flood discharges may account for an additional 1 2 times 10 9 tons about 70 of this total is derived from southern asia and the larger islands in the pacific and indian oceans where sediment yields are much greater than for other drainage basins

passive bottom reflection loss estimation using ship noise and a vertical line array an existing technique for passive bottom loss estimation from natural marine surface noise generated by waves and wind is adapted to use noise generated by ships the original approach based on beamforming of the noise field recorded by a vertical line array of hydrophones is retained however additional processing is needed in order for the field generated by a passing ship to show features that are similar to those of the natural surface noise field a necessary requisite is that the ship position relative to the array varies over as wide a range of steering angles as possible ideally passing directly over the array to ensure coverage of the steepest angles the methodology is illustrated through simulation and applied to data from a field experiment conducted offshore of san diego ca in 2009

faulting and extension rate over the last 20 000 years in the offshore whakatane graben new zealand continental shelf oblique rifting in the offshore taupo volcanic zone new zealand is expressed in widely distributed active normal faulting in the 20 km wide whakatane graben active faults are identified along seafloor scarps and displacements of the post last glacial transgressive ravinement surface 400 faults we derive an extension rate at seismogenic depths 6 10 km across the graben of 13 6 mm yr by summing surface measurements assuming an average crustal fault dip of 45 15o and correcting for the discrepancies between surface and deep crustal extension estimates structural and kinematic data implies an extension direction 20o oblique to the rift axis resulting in up to 4 6 2 1 mm yr of dextral motion parallel to the rift axis the strike slip motion is accommodated by dip slip displacements on oblique faults in the centre of the graben and oblique slip faulting along the rift margins pure dip slip in the graben centre represents 50 of the total slip with the rangitaiki fault accommodating 25 of the total extension in the graben

the role of coseismic coulomb stress changes in shaping the hard link between normal fault segments the mechanism and evolution of fault linkage is important in the growth and development of large faults here we investigate the role of coseismic stress changes in shaping the hard links between parallel normal fault segments or faults by comparing numerical models of the coulomb stress change from simulated earthquakes on two en echelon fault segments to natural observations of hard linked fault geometry we consider three simplified linking fault geometries 1 fault bend 2 breached relay ramp and 3 strike slip transform fault we consider scenarios where either one or both segments rupture and vary the distance between segment tips fault bends and breached relay ramps are favoured where segments underlap or when the strike perpendicular distance between overlapping segments is less than 20 of their total length matching all documented examples transform fault linkage geometries are preferred when overlapping segments are laterally offset at larger distances few transform faults exist in continental extensional settings and our model suggests that propagating faults or fault segments may first link through fault bends or breached ramps before reaching sufficient overlap for a transform fault to develop our results suggest that coulomb stresses arising from multi segment ruptures or repeated earthquakes are consistent with natural observations of the geometry of hard links between parallel normal fault segments

interaction and linkage of extension fractures and normal faults examples from the rift zone of iceland abstract field and photogeological studies were made of 90 zones of interacting fracture segments along the rift zone of iceland each zone consists of a pair of extension fractures or a pair of normal faults with lengths from metres to kilometres these zones evolve from an underlapping stage through an overlapping stage the most common configuration and finally to a linkage stage of all the zones only 7 are underlapping whereas 93 are overlapping with hook shaped fracture pairs the length width ratios of the overlapping zones have a mean value of 3 5 the preferred geometry of the overlapping zones depends upon the initial configuration of the interacting fractures length overstep and the development of the interaction in the overlapping zones most fracture pairs show moderate shear strike slip components related to local variations in the extension opening directions vertical displacements on normal faults decrease as the overstep and length of overlapping zones increase both in turn are proportional to the total lengths of the faults forming the pair the geometrical and kinematic features of overlapping spreading centres at mid ocean ridges show close similarities to those reported here these similarities indicate that the architecture and evolution of overlapping zones are scale independent

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

sediment yield in europe spatial patterns and scale dependency abstract our understanding about the regional variation of sediment yield sy in europe and its scale dependency currently relies on a limited number of data for mainly larger river systems sy is the integrated result of all erosion and sediment transporting processes operating in a catchment and is therefore of high value for environmental studies and monitoring purposes most global assessments of sy consider catchment area a climate and topography as the main explanatory variables however it is still unclear if these factors also control regional variations of sy within europe this paper aims at bridging this gap therefore we i present a large database of sy values which was constructed through an extensive literature review ii describe the spatial patterns of sy across europe and iii explore its relation with a climate and topography in total sediment yield data from 1794 different locations throughout europe were collected 507 reservoirs and 1287 gauging stations representing a minimum of 29 203 catchment year data only sy data measured at gauging stations or derived from reservoir siltation rates over a period of a minimum of one year were included in the database this database comprises a large range of catchment areas a i e from small upland catchments 0 01 km to major european river basins 1 360 000 km an overview of the collected sy data is provided and sources of uncertainty on the available data are discussed despite potentially large uncertainties on several of the individual sy values analysis of this database indicates clear spatial patterns of sy in europe the temperate and relatively flat regions of western northern and central europe generally have relatively low sy values with ca 50 of the sy 40 t km 2 yr 1 and ca 80 of the data 2 yr 1 while mediterranean and mountainous regions generally have higher sy values with around 85 of the sy data 40 t km 2 yr 1 and more than 50 of the data 200 t km 2 yr 1 these differences are attributed to a combination of factors such as differences in climate topography lithology and land use although larger differences in sy were found between the climatic regions than between topographic zones it is currently difficult to identify the individual importance of the various controlling factors of sy sy a relationships were calculated for the entire dataset and for subgroups stratified according to the measurement method gauging stations or reservoir surveys range of the catchment area climatic region topographic zone of the river outlet and major european river system although typically a negative relationship between sy and a is expected due to a decrease in topsoil erosion rates on more gentle slopes and an increase in sediment deposition with an increase in catchment size this relationship was found to be generally very weak and subject to a lot of scatter furthermore results illustrate important differences in scale dependency whereas a weak but significant negative trend is generally observed for the temperate and relatively flat regions no significant or even positive trends were observed in mountain regions and mediterranean europe when only larger river catchments i e 100 km and especially 10 000 km are considered catchment area exerted a larger control on sy these findings confirm previous studies and indicate that the relationship between sy spatial scale and other controlling factors is often complex and non linear

the sediment delivery problem abstract the linking of on site rates of erosion and soil loss within a drainage basin to the sediment yield at the basin outlet and improved knowledge and representation of the associated processes of sediment delivery represent a major research need within the field of erosion and sedimentation and also an important scale problem in drainage basin studies this paper reviews the limitations of the sediment delivery ratio concept by considering the problems of temporal and spatial lumping and its blackbox nature some recent advances in our understanding of the sediment delivery system and its modelling are described and the lack of detailed empirical investigations is highlighted the significance of recent concern for the role of sediments in the transport of nutrients and contaminants to sediment delivery studies is introduced and the need for further work in this field is emphasised

thermomechanics of mid ocean ridge segmentation the mechanics responsible for the initiation of the orthogonal pattern characterizing mid ocean ridges and transform faults are studied using numerical models the driving forces are thermal stresses arising from the cooling of young oceanic crust and extensional kinematic boundary conditions thermal stress can exert ridge parallel tension comparable in magnitude to spreading induced tension when selectively released by ridges and ridge parallel structure two modes of ridge segment growth have been identified in plan view an overlapping mode where ridge segments overlap and bend toward each other and a connecting mode where two ridge segments are connected by a transform like fault as the ratio of thermal stress to spreading induced stress increases the patterns of localized plastic strain change from the overlapping to connecting mode the orthogonal pattern marks the transition from one mode to the other besides the amount of stress from each driving force the rate of stress accumulation is crucial in determining the emergent pattern this rate dependence is characterized by the spreading rate normalized by a reference cooling rate pe when pe is paired with the ratio of thermal stress to the reference spreading induced stress they unambiguously define stability fields of the two modes the obliquely connecting the orthogonally connecting and the overlapping mode are similar to ridge transform fault intersections observed in ultra slow slow to intermediate and fast spreading centers respectively the patterns are also sensitive to the strain weakening rate fracture zones were created in part as a response to thermal stress

extensional hard linkages eastern gulf of suez egypt the araba abu durba area on the eastern margin of the gulf of suez exhibits two superb outcrop examples of extensional hard linkages in a rift basin here three large domino style basement cored northeast dipping fault blocks are formed by a series of major northwest trending normal faults these are offset by two north northeast trending sinistral oblique slip transfer faults that terminate in horsetail normal fault splays the transfer faults do not extend across the entire rift basin detailed mapping and structural analysis show that they developed by breakage of initial low strain relay ramps along reactivated north northeast trending basement fabrics between overlapping northwest trending normal fault segments paleostrain analysis of fault slip indicators shows that both the normal and the sinistral oblique slip transfer faults were formed synchronously in response to northeast southwest extension perpendicular to the main northwest rift trend

extensional deformation and paleomagnetism at the western margin of the gulf extensional province puertecitos volcanic province northeastern baja california mexico during the late miocene east northeast directed extension in the gulf of california extensional province the western rift margin in northeastern baja california mexico was segmented at the northwest striking matomi accommodation zone the accommodation zone passed through the northern puertecitos volcanic province and separated pre 6 ma extension to the north from the unextended region to the south pre 6 ma northeast side down displacement is documented across the accommodation zone which may have undergone dextral oblique slip motion the rift margin migrated westward during the latest miocene or pliocene bypassing accommodation zone structures and incorporating the puertecitos volcanic province into the region of gulf extensional province deformation east northeast to east directed extensional deformation is at least post 6 ma in the northern puertecitos volcanic province and deformation currently continues pliocene changes in the gulf of california spreading center system may have triggered incorporation of the puertecitos volcanic province into the gulf extensional province as recently as 2 3 ma paleomagnetic analyses of 6 3 6 6 ma pyroclastic flow deposits show no consistent evidence for rotational deformation although minor 10 15 clockwise rotation is possible given anomalous declination directions recorded at some sites comparisons with paleosecular variation models and the late miocene paleopole for stable north america imply no statistically significant rotation relative to geomagnetic north although minor 10 clockwise rotation is permissible given uncertainties geologic relationships show that pre 6 ma accommodation zone structures identified in this study did not mark the southern boundary of later rotational deformation documented to the north the boundary of pliocene to holocene rotations may be a broad diffuse zone of extensional shear encompassing the northeastern puertecitos volcanic province which accommodated small rotations

sand box modelling of basement controlled transfer zones in extensional domains the interaction modalities of transfer zones connecting rift segments may be influenced by several factors amongst these the location and architecture of transfer zones in narrow rifts has been repeatedly associated with the presence of inherited basement anisotropies sand box models were made to investigate how the orientation geometry and kinematics of transfer zones depend upon pre existing basement anisotropies analogue models reproduced offset rift segments linked by transfer zones bordered by arcuate normal faults strike slip faults are present inside the transfer zone provided that angle between the extension direction and the axis of the transfer zone is less than 50 narrower transfer zones striking oblique to the extension direction occur for angle between the direction perpendicular to the extension direction and the direction of the basement anisotropy less than 90 wider transfer zones subparallel to the extensional direction occur for 90 increasing the overstep induces narrower transfer zones striking subparallel to the extension direction similar geometrical and kinematical patterns have been found at transfer zones in narrow rifts the comparison between experimental and natural data shows how the geometry kinematics and orientation of natural transfer zones depends upon the trend of inherited anisotropies transfer zones along inherited basement structures set at lower angles to the extension direction and display lower aspect ratios than transfer zones where inherited anisotropies are absent

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

controls budgets and variability of riverine sediment fluxes to the gulf of lions nw mediterranean sea the present study investigates the spatio temporal variability of riverine sediment fluxes to the gulf of lions one of the most extensive shelf regions in the mediterranean sea small coastal rivers compete here with the rhone river nowadays the largest mediterranean river in terms of water discharge our scientific objectives were to investigate the major controls of riverine sediment yields sy in this area and to quantify the role of the small coastal rivers largely ignored in previous studies in the total sediment budgets another objective concerned the source identification of the rhone sediments with regard to the major tributary contributions and to test whether the sediment fluxes are in equilibrium in the basin for the calculation of representative long term fluxes we used a simplified rating curve approach sirca which could be validated by high resolution monitoring and existing literature data an overall of 13 drainage basins could be distinguished covering about 86 of the study area 6 coastal rivers the rhone river and 6 of its tributaries representative sy range from 19 to 151 t km 2 yr 1 in the investigated drainage basins despite their smaller basin areas and more torrential discharge regimes sy of the coastal rivers were generally lower compared to sy of the rhone river and its tributaries confrontation with the lithological morphological and hydroclimatic basin characteristics indicate that lithology exerts the dominant control on sy in the study region in particular the existence of erodible sedimentary rocks in the headwater regions yields high sy peak values of 135 and 151 t km 2 yr 1 were observed for the isere and durance tributaries of the rhone river where badlands exist the coastal rivers contribute on average only to slightly more than 5 of the long term sediment inputs to the gulf of lions during individual years however their contribution can strongly increase up to 27 in 2011 their contribution is generally important during late spring and autumn when flash floods are frequent up to 90 of the monthly sediment discharge summing the various tributary contributions of the rhone river produces a sediment budget that is close to the sediment export at the river mouth this indicates that at spatial scales the average sediment fluxes are equilibrated in the basin about 40 of the rhone sediments originate from the isere and durance tributaries however fully closure of the budgets requires high sy in the lowermost basin parts omitting in our calculations only a few years with exceptional flooding considerably reduce these values trend analyses show at the same time that the sediment fluxes from the saone and isere tributaries decreased during the study period at temporal scales sediment transport from upstream to downstream was therefore not in equilibrium and the remobilisation of older sediments from the downstream basin parts may have been important

transfer zones in an oblique back arc basin setting insights from the latium campania segmented margin tyrrhenian sea new multichannel seismic reflection profiles were acquired to unravel the structure of a portion of the eastern margin of the tyrrhenian basin this extensional feature is part of an oligocene to present back arc basin in the hangingwall of the west directed apennines subduction system the basin provides excellent conditions to investigate the early stage processes leading to the development of rifted passive margins and to the emplacement of oceanic crust in an oblique setting the interpreted post stack migrated seismic profiles highlight the geometry and kinematics of the pontine escarpment that connects the latium campania continental margin to the vavilov basin the latter is the main feature of the area related to the early pliocene extension of the tyrrhenian sea several morphological variations are pointed out along strike mirroring different structural settings of the margin itself a steeper margin to the north corresponds to high angle possibly transtensional faults whereas a smooth slope in the southern portion corresponds to several more distributed listric faults this work contributes to the understanding of the interplay between extensional and transtensional tectonics along the margins of an oblique back arc basin

what controls relay ramps and transfer faults within rift zones insights from analogue models abstract structures within rift zones exhibit two main types of interaction relevant at the rift scale relay ramps and transfer faults at high angle to the rift analogue experiments have been performed to investigate whether these types of interaction may be affected by differential extension along the rift in these models sand brittle crust analogue overlies two adjacent silicone ductile crust analogue layers with different viscosity in order to simulate different percentage extension rates e along rifts the experiments show a distinct behaviour as a function of e for e e 21 3 the interaction occurs by means of transfer faults striking subparallel to the extension direction experimental data are consistent with the geometries and extension rates of rift zones relay ramps characterize narrow rifts and oceanic ridges where the mean percentage of extension is low e e 39 where the rift more likely achieves differential extension e 21

erosion quantification in the small marly experimental catchments of draix alpes de haute provence france calibration of the etc rainfall runoff erosion model abstract erosion rates measured for 15 years in the small ranging from 0 13 ha to nearly 1 km2 and steep 30 75 mountainous marly basins of draix south alps france are over 100 tons ha year in a badland area devoid of vegetation in a similar basin reforested at the end of the 19th century the sediment yield is considerably reduced less than 3 tons ha year the analysis of the sediment yield of these torrents reveals the importance of the erosion processes on slopes at the scale of the elementary gully and the influence of deposition transport and scouring processes as soon as the channel network of the basin is developed these processes were modelled by a hydrosedimentologic model developed by cemagref for flood torrent erosion and called etc etc is an integrated spatialized and global model working at the event scale the rainfall runoff component and the solid transport component which involves scouring deposition and armouring are well developed on the other hand the erosion component is not yet a physically based model as the knowledge on the elementary processes is not enough quantitative the etc model was used on a badland basin of 86 ha in area the laval and has shown its ability to simulate both water and sediment flows in mountainous and steep basins the erosion modelling highlighted the need for a better representation of the slope processes and for more information on the storing of sediments in the channel network observations carried out on the influence of the vegetation cover patterns and the links between slopes and channels should be taken into account to improve the model

heterogeneous extension and the role of transfer faults in the development of the southeastern betic basins se spain large strike slip faults in the eastern betics are interpreted to have developed in a transcurrent setting in response to 4 6 mm yr of africa iberia nw se convergence however here we show that some of these faults are transfer faults accommodating heterogeneous late miocene extension the north cabrera dextral fault and other e w to ne sw strike slip faults in the sorbas basin were transfer faults produced under sw ne extension these faults together with related normal faults form the main boundaries of two sedimentary depocenters active between the serravallian and the tortonian the older north cabrera depocenter extended between the serravallian and the early tortonian approximately 13 8 to 9 ma while the younger gacia depocenter formed in response to late tortonian extension approximately 9 to 7 5 ma the latter formed to the west of the north cabrera depocenter by a listric fan of normal faults with sw directed transport that are linked by dextral and sinistral transfer fault segments these faults root on a low angle detachment cutting into the exhumed high pressure nevado filabride complex rocks at 0 8 km depth the present work reveals that 1 this extension was partially coeval with and kinematically linked to sinistral displacement along the carboneras fault farther south in the nijar basin 2 this westward directed extension produced elongated core complexes and tilted blocks to the north of the carboneras fault and magmatic accretion upon thinned continental crust to the south probably in response to slab tearing or detachment and associated edge delamination of the iberian continental lithospheric mantle beneath the betics

complex rift geometries resulting from inheritance of pre existing structures insights and regional implications from the barmer basin rift abstract structural studies of the barmer basin in rajasthan northwest india demonstrate the important effect that pre existing faults can have on the geometries of evolving fault systems at both the outcrop and basin scale outcrop exposures on opposing rift margins reveal two distinct non coaxial extensional events on the eastern rift margin northwest southeast extension was accommodated on southwest and west striking faults that form a complex zig zag fault network on the western rift margin northeast southwest extension was accommodated on northwest striking faults that form classical extensional geometries combining these outcrop studies with subsurface interpretations demonstrates that northwest southeast extension preceded northeast southwest extension structures active during the early previously unrecognised extensional event were variably incorporated into the evolving fault systems during the second in the study area an inherited rift oblique fault transferred extension from the rift margin to a mid rift fault rather than linking rift margin fault systems directly the resultant rift margin accommodation structure has important implications for early sediment routing and depocentre evolution as well as wider reaching implications for the evolution of the rift basin and west indian rift system the discovery of early rifting in the barmer basin supports that extension along the west indian rift system was long lived multi event and likely resulted from far field plate reorganisations

geoacoustic inversion of ship radiated noise in shallow water using data from a single hydrophone the centre for maritime research and experimentation conducted a geoacoustic inverse experiment in the mediterranean sea in the summer of 2012 among the objectives was to employ an autono mous underwater vehicle to collect acoustic data to invert for properties of the seafloor inversion results for the compression wave speed in the bottom and the source spectrum of the r v alliance during a close approach to the bottom moored vehicle are presented the estimated wave speed was 1529m s r 10 the source spectrum of the alliance was estimated across more than six octaves of frequency

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

matched field processing geoacoustic inversion and source signature recovery of blue whale vocalizations matched field processing mfp and global inversion techniques have been applied to vocalizations from four whales recorded on a 48 element tilted vertical array off the channel islands in 1996 global inversions from selected whale calls using as few as eight elements extracted information about the surrounding ocean bottom composition array shape and the animal s position these inversion results were then used to conduct straightforward mfp on other calls the sediment sound speed inversion estimates are consistent with those derived from sediment samples collected in the area in general most animals swam from the east to west but one animal remained within 500 m of its original position over 45 min all whales vocalized between 10 and 40 m depth three acoustic sequences are discussed in detail the first illustrating a match between an acoustic track and visual sighting the second tracking two whales to ranges out to 8 km and the final sequence demonstrating high resolution dive profiles from

the impact of ocean sound speed variability on the uncertainty of geoacoustic parameter estimates this paper investigates the influence of water column variability on the estimates of geoacoustic model parameters obtained from matched field inversions the acoustic data were collected on the new jersey continental shelf during shallow water experiments in august 2006 the oceanographic variability was evident when the data were recorded to quantify the uncertainties of the geoacoustic parameter estimates in this environment bayesian matched field geoacoustic inversion was applied to multi tonal continuous wave data the spatially and temporally varying water column sound speed is parametrized in terms of empirical orthogonal functions and included in the inversion its impact on the geometric and geoacoustic parameter estimates is then analyzed by the inter parameter correlations two different approaches were used to obtain information about the variation of the water sound speed one used only the profiles collected along the experimental track during the experiment and the other also included observations collected over a larger area the geoacoustic estimates from both the large and small sample sets are consistent however due to the diversity of the oceanic sound speed more empirical orthogonal functions are needed in the inversion when more sound speed profile samples are used

morphotectonics inferred from the analysis of topographic lineaments auto detected from dems application and validation for the sinai peninsula egypt abstract morphotectonic lineaments observed on the sinai peninsula in egypt were auto detected from shuttle radar topography mission 90 m digital elevation model dem and gravity grid data and then analyzed to characterize the tectonic trends that dominated the geologic evolution of this area the approach employed consists of dem shading segment tracing grouping statistical analysis of the distribution and orientation of the lineaments fault plane characterization and smooth representation techniques statistical quantification of counts mean lengths densities and orientations was used to infer the relative severity of the tectonic regimes to unravel the prominent structural trends and to demarcate the contribution of various faulting styles that prevailed through time restored to the present day geographic position prominent n50 60 w n20 40 w n50 60 e and n20 30 e and less prominent n s e w and ene trends were common the prominence of these trends varied through time the nw and ne trends showed relatively equal abundances in the precambrian and the cambrian whereas the prominence of the nw trends prevailed from the carboniferous to the holocene lineaments in all formations were near vertical and on average about 65 showed as strike slip 22 as reverse and 13 as normal faulting styles statistics from the detected linear features and the reference geological data reveal the relative severity of five dominant tectonic regimes precambrian compression followed by extension at its end cretaceous compression eocene compression miocene extension and finally holocene compression auto detected lineaments and the severity of the characterized tectonic periods correspond well with reference data on the geologic structure geodynamic framework and the gravity anomaly furthermore the recent significance of the broad structural zones was confirmed by the foci of the earthquake epicenters along and at the intra plate intersections of the broad lineament zones and at the plate boundaries the spatial distribution of trends with varying styles of faulting distinguished four main tectonic provinces of marked geodynamics variances

insights into the effects of oblique extension on continental rift interaction from 3d analogue and numerical models abstract continental rifts often develop from linkage of distinct rift segments under varying degrees of extension obliquity these rift segments arise from rift initiation at non aligned crustal heterogeneities and need to interact to develop a full scale rift system here we test the effects of 1 oblique extension and 2 initial heterogeneity seed offset on continental rift interaction with the use of an improved analogue model set up x ray computer tomography ct techniques are used to analyse the 3d models through time and the results are compared with additional numerical models and natural examples the experimental results reveal that increasing extension obliquity strongly changes rift segment structures from wide rifts in orthogonal settings to narrower rifts with oblique internal structures under oblique extension conditions to narrow strike slip dominated systems towards the strike slip domain we also find that both decreasing seed offset and increasing extension obliquity promote hard linkage of rift segments through the formation of continuous rift boundary faults at the surface initial soft linkage through the formation of relay ramps is more likely when seed offset increases or extension is more orthogonal rather than linking at depth the rift boundary faults curve around each other at depth and merge towards the surface to form a continuous trough orthogonal extension promotes the formation of intra rift horsts which may provide hydrocarbon traps in nature

seasonal variations of physical and chemical erosion a three year survey of the rhone river france abstract numerous studies of weathering fluxes have been carried out on major world rivers during the last decade to estimate co 2 consumption rates landscape evolution and global erosion rates for obvious logistical reasons most of these studies were based on large scale investigations carried out on short timescales by comparison much less effort has been devoted to long term monitoring as a means to verify the temporal variability of the average characteristics their trends and the representativeness of short term investigations here we report the results of a three year survey november 2000 to december 2003 of the major and trace element composition of dissolved and suspended matter in the lower rhone river france the largest river of the mediterranean area subsurface water samples were collected in arles about 48 km upstream of the estuary twice a month routinely and at higher frequency during flood events during each flood event the suspended particulate matter spm show the usual trend of clockwise hysteresis with higher spm concentrations on the rising limb of the flood than at the same discharge on the falling limb we show that the annual average spm flux of the rhone river to the mediterranean sea 7 3 0 6 10 6 tons yr 1 was largely controlled by the flood events 83 of the solid discharge occurred in less than 12 of the time and that the precision on the total output flux depends strongly on the precise monitoring of spm variations during the floods the chemical composition of water and spm are characterized by the predominance of ca 2 due to the abundance of carbonate rocks in the rhone watershed chemical budgets have been calculated to derive the contributions of atmospheric deposition carbonate silicate and evaporite weathering and anthropogenic inputs the chemical weathering rate of carbonates is estimated to be 89 5 t km 2 yr 1 compared to 14 4 3 t km 2 yr 1 from silicates by contrast the physical erosion rate of silicates is about 51 t km 2 yr 1 against 19 t km 2 yr 1 for carbonates the steady state model of gaillardet et al 1995 has been applied to the chemical composition of dissolved and solid products the results show that the rhone river currently exports much less material than produced at steady state by weathering in its watershed the sediment flux inferred from the steady state calculation 21 56 10 6 t yr 1 is on the same order as that estimated in literature for the 19th and the beginning of the 20th centuries this imbalance may suggest that the rhone is under a transient erosion regime following climate change i e significant decrease of the flooding frequency since the beginning of the 19th century on the other hand the imbalance may also be due to the trapping of alluvion by the numerous dams on the river and its tributaries our data corroborate with previous studies that suggest a strong coupling between chemical and physical erosion fluxes during the hydrological seasonal cycle of the rhone river the correlation between physical and chemical transport rates is however clearly different from that reported for global annual averages in large world rivers

inland jump of the arabian northwest plate boundary from the levant continental margin to the dead sea transform 1 while the breakup of arabia and africa began in the early oligocene the northwestern boundary of the arabian plate along the dead sea transform dst formed 10 15 myr later early middle miocene during the early stage of breakup the red sea rift continued propagating northwestward forming the suez rift the present 45 northward twist of the plate boundary from the red sea toward the gulf of eilat aqaba still did not exist what happened at the northern tip of the suez rift at that time how was strain distributed to its surroundings and where did the plate boundary continue from there here we describe an abandoned segment of the arabian northwestern plate boundary that extended from the northern tip of the suez rift northeastward along the levant margin seismic data collected offshore israel support a subsurface deep rooted fault zone running along the base of the continental slope these faults indicate oligocene transpressional lateral shearing we propose that during the early stage of continental breakup a left lateral strike slip motion of 10 km took place along this embryonic plate boundary such deep rooted tectonism implies that unlike the passive situation of the israel sinai continental margin witnessed presently and before the oligocene during the early stage of the africa arabia breakup this part of the continental margin was reactivated we further suggest that the inland jump of the plate boundary toward the dst was not immediate and that during the transitional period the israel sinai triangular block was an independent subplate with deformation all around it

origin and models of oceanic transform faults abstract mid ocean ridges sectioned by transform faults represent prominent surface expressions of plate tectonics a fundamental problem of plate tectonics is how this pattern has formed and why it is maintained gross scale geometry of mid ocean ridges is often inherited from respective rifted margins indeed transform faults seem to nucleate after the beginning of the oceanic spreading and can spontaneously form at a single straight ridge both analog and numerical models of transform faults were investigated since the 1970s two main groups of analog models were developed thermomechanical freezing wax models with accreting and cooling plates and mechanical models with non accreting lithosphere freezing wax models reproduced ridge ridge transform faults inactive fracture zones rotating microplates overlapping spreading centers and other features of oceanic ridges however these models often produced open spreading centers that are dissimilar to nature mechanical models on the other hand do not accrete the lithosphere and their results are thus only applicable for relatively small amount of spreading three main types of numerical models were investigated models of stress and displacement distribution around transforms models of their thermal structure and crustal growth and models of nucleation and evolution of ridge transform fault patterns it was shown that a limited number of spreading modes can form transform faults microplates overlapping spreading centers zigzag ridges and oblique connecting spreading centers however the controversy exists whether these patterns always result from pre existing ridge offsets or can also form spontaneously at a single straight ridge during millions of year of accretion therefore two types of transform fault interpretation exist plate fragmentation structures vs plate accretion structures models of transform faults are yet relatively scarce and partly controversial consequently a number of first order questions remain standing and significant cross disciplinary efforts are needed in the future by combining natural observations analog experiments and numerical modeling

displacement transfer between intersecting regional strike slip and extensional fault systems interaction and displacement transfer between active intersecting strike slip or transform and extensional fault systems are examined outcrop data from a well preserved strike slip fault and rift intersection in new zealand are compared to a global data set of 13 such intersections in both continental and oceanic crust displacement transfer between strike slip and normal faults is typically accomplished by gradual changes of fault orientations and slip vectors close to the intersection zone for two and three plate configurations these changes result in sub parallelism of the slip vectors of the component faults with their line of intersection the dimensions of the area over which fault strike and slip vectors change are principally controlled by the extent to which displacements on the dominant of the two intersecting fault systems are confined to a single slip surface or distributed across a zone where slip is spatially distributed the region in which the two displacement fields are superimposed produces transtension and associated oblique slip this distributed off fault deformation facilitates the development of a quasi stable configuration of the fault intersection region maintaining both the regional geometry and kinematics of the intersection zone which in many cases would not be possible for rigid block translations the dimensions of the transition zone are larger for continental crust than for oceanic crust because oceanic crust is thinner fault geometries in oceanic crust are simpler two plate configurations and the slip vectors of the component intersecting fault systems are sub parallel

paleomagnetic structural and stratigraphic constraints on transverse fault kinematics during basin inversion the pamplona fault pyrenees north spain 1 the pamplona fault in the pyrenees is a major transverse structure that has been classically interpreted as a strike slip fault however lack of consensus concerning the sense of movement casts doubt on its actual kinematics and as a consequence its role in the cenozoic evolution of the pyrenees remains controversial in order to assess its kinematics we have conducted a paleomagnetic structural and stratigraphic study focused on the mesozoic and tertiary sedimentary rocks that outcrop around the southern segment of the fault restoration of balanced cross sections allows us to examine the present day spatial relationship of the sedimentary sequences on both sides of the fault and to reconstruct the geometry of the extensional basins formed during mesozoic rifting episodes in the bay of biscay and pyrenean domains paleomagnetic results indicate that no significant tectonic rotations occurred around the fault during tertiary inversion of the pyrenees the lack of tectonic rotations and revaluation of previous hypotheses argues against a strike slip movement of the fault we propose a new model in which the pamplona fault is treated as a large scale hanging wall drop fault whose kinematics was determined by variations in the geometry and thickness of mesozoic sequences on both sides of the fault these variations influenced the geometry of the thrust sheet developed during tertiary compression we are unaware of any other transverse fault that has been interpreted in this fashion thus the pamplona fault serves as a case study for the evolution of transverse faults involved in basin inversion processes

inversion for range dependent water column sound speed profiles on the new jersey shelf using a linearized perturbative method the environment of the new jersey shelf is characterized by high spatial and temporal variability of water column properties caused by intrusions of warm salty water from the continental slope these intrusions cause fluctuations in the water column sound speed profile which can have significant effects on acoustic propagation in shallow water in this work a linearized perturbative inverse technique is applied to estimate range dependent water column sound speed profiles this method utilizes estimates of horizontal wave numbers to determine sound speed as a function of depth this technique is appropriate for the range dependent shallow water environment as horizontal wave numbers can be measured semilocally 1 2 km aperture and their values are a direct measurement of the local environmental parameters difficulty is encountered in application of the perturbative inverse technique because the wave number data are insensitive to some portions of the waveguide and as a result the solution can deviat

control of extensional transfer zones on syntectonic and post tectonic sedimentation implications for hydrocarbon exploration the gulf of suez red sea rift system exhibits superb outcrop examples of extensional transfer zones and displays the control of these zones on syntectonic and post tectonic sedimentation hard and soft linkage transfer zones were identified at variable scales hard linkage transfer zones form inward and outward fault kinks whereas soft linkage transfer zones form relay ramps between overlapping rift parallel faults the two types of transfer zones invariably exerted fundamental control on the deposition of syn and post tectonic sediments flow direction of drainage systems and locations of sediment entry points as well as the intensity of erosion patterns of the structurally high sediment source areas this study highlights the close relationship between the transfer zones and hydrocarbon accumulations in clastic syntectonic reservoirs in rift basins

parameter estimation using multifrequency range dependent acoustic data in shallow water the estimation of all forward model parameters geometric geoacoustic and ocean sound speed by the inversion of acoustic field observations is considered the data was taken at a mildly range dependent shallow water site in the mediterranean sea the inversion is based on data from a vertical array and carried out using information at multiple frequencies global optimization using a directed monte carlo search based on genetic algorithms and the bartlett objective function is used all geometric parameters are well determined a range dependent geoacoustic model is determined and the ocean sound speed is estimated comparisons of the observed pressure field as a function of depth and the predicted field show good agreement the use of observations at multiple frequencies provides considerable stability for the estimated parameters optimization of only geometric and geoacoustic parameters in a range independent environment is found to be satisfactory at the lower frequencies 165 175 hz but for the h

inversion for sediment geoacoustic properties at the new england bight this article discusses inversions for bottom geoacoustic properties using broadband acoustic signals obtained from explosive sources two different inversion schemes for estimating the compressional wave speeds and attenuation are presented in this paper in addition to these sediment parameters source receiver range is also estimated using the arrival time data the experimental data used for the inversions are sus charge explosions acquired on a vertical hydrophone array during the shelf break primer experiment conducted south of new england in the middle atlantic bight in august 1996 the modal arrival times are extracted using a wavelet analysis in the first inversion scheme arrival times corresponding to various modes and frequencies from 10 to 200 hz are used for the inversion of compressional wave speeds a hybrid inversion scheme based on a genetic algorithm ga is used for the inversion in an earlier study potty et al j acoust soc am 108 3 973 986 2000 have used this hybrid scheme in a range independent environment in the present study results of range dependent inversions are presented the sound speeds in the water column and bathymetry are assumed range dependent whereas the sediment compressional wave speeds are assumed range independent the variations in the sound speeds in the water column are represented using empirical orthogonal functions eofs the replica fields corresponding to the unknown parameters were constructed using adiabatic theory in the second inversion scheme modal attenuation coefficients are calculated using modal amplitude ratios the ratios of the modal amplitudes are also calculated using time frequency diagrams a ga based inversion scheme is used for this search finally as a cross check the computed compressional wave speeds along with the modal arrival times were used to estimate the source receiver range the inverted sediment properties and ranges are seen to compare well with in situ measurements and historical data

what factors control mechanical erosion rates mechanical erosion rates are important factors in understanding how continents evolve mechanical erosion is much faster than chemical erosion especially for highly elevated regions of the earth s surface it is a principal way in which mountain ranges are removed exposing deep metamorphic roots which comprise much of the older portions of the continental masses in addition there has to be a long term balance between erosion and mountain building a new data set allows us to explore in greater detail some of the many factors which control mechanical erosion rates the most important factors are some expression of the average slope of a drainage basin some measurement of the amount of water available for erosion some environmental measurements and also a measurement of basin length for which we have no good explanation the estimate of global mechanical erosion rate obtained here is considerably lower than those obtained by some other workers some of whom have concentrated on the fact that smaller river basins tend to get eroded faster than larger basins and it is mainly smaller basins which have not been measured and which are therefore not allowed for by simple arithmetic averaging of observed erosion rates it is shown here that although smaller basins are eroded faster this is mainly because they are steeper than larger basins we also show that extrapolation of current data to smaller basins does not work because the observed continental area which is draining to the ocean cannot be attained by the simplest extrapolation scheme

three dimensional thermomechanical modeling of oceanic spreading initiation and evolution abstract this work employs high resolution 3d thermomechanical numerical models of the incipient oceanic spreading to investigate nucleation and long term evolution of ridge transform spreading patterns the eulerian lagrangian visco plastic model allows for large strains and accounts for plate cooling by both heat conduction and hydrothermal circulation as well as for partial melting of the asthenosphere and oceanic crust growth by magmatic accretion according to the numerical experiments the oceanic spreading pattern depends strongly on the initial offset of spreading centers and the magnitude of fracture healing rate three different characteristic long term spreading modes are obtained 1 ridge transform patterns 2 single ridges and 3 spreading centers with an intermediate plate ridge transform oceanic spreading patterns form gradually from moderate initial offsets of 40 60 km and become fully established several million years after the plate breakup moreover it is demonstrated on the basis of simple analyses that the ridge transform system is a long term plate growth pattern that is generally different from an initial plate rifting pattern geometry of the ridge transform system is governed by geometrical requirements 180 rotational symmetry for open space occupation for simultaneous accretion and displacement of new plate material within two offset spreading centers connected by a sustaining rheologically weak transform fault according to these requirements the characteristic spreading parallel orientation of oceanic transform faults is the only thermomechanically consistent steady state orientation results of numerical experiments compare well with both incipient and mature ridge transform systems observed in nature