imaging topographic growth by long lived postseismic afterslip at sefidabeh east iran this paper describes observations and models of the postseismic deformation following the 1994 sefidabeh earthquake sequence in east iran which shed light on the nature of the earthquake cycle and the mechanisms of topographic growth in the region interferometric synthetic aperture radar observations show creeping fault motion postseismic afterslip on an array of faults some of these faults probably represent the extensions of those that ruptured in the blind thrust faulting earthquakes in 1994 and cut through the entire seismogenic layer while others are shallow and break up the hanging walls of the coseismic faults the postseismic slip accommodates at least part of the vertical displacement gradient resulting from the buried coseismic slip which was concentrated at depths of greater than 5 km the postseismic afterslip is visible for over 16 years following the earthquakes agreement between the areas of postseismic uplift and indications of long term motion preserved in the geomorphology suggest that shallow fault slip during seismic cycles similar to the one we have observed governs the development of the landscape in the region slip on an array of shallow faults provides a mechanism for the development of short wavelength topography and geological structures above active thrust faults and has important implications for the interpretation of shallow geological features produced in regions experiencing similar seismic cycles to that at sefidabeh

effect of stone content on water flow velocity over loess slope non frozen soil abstract stony soils are commonly found worldwide and are considerably studied for their hydrological characteristics and effect on soil erosion water flow velocity is an important parameter in understanding the effect of stone content on hydrodynamics and soil erosion in this study laboratory experiments were used to measure rill flow velocity by using electrolyte tracer method under different hydraulic conditions flow rates of 1 2 4 and 8 l min slope gradients of 5 10 15 and 20 and stone mass contents amounting to 0 10 20 and 50 nine sensors which were 1 m apart along the 8 m long rill were used to measure flow velocity by tracing solute transport measured flow velocity increased with slope gradient and flow rate the highest increase in flow velocity was measured from 15 to 20 which were also affected by flow rate effects of discharge rate on flow velocity presented the largest difference when flow rate increased from 2 l min to 8 l min at slope gradients higher than 5 the effects of different factors were quantified by a regression model with high accuracy of 0 99 maximum flow velocity of water was predicted at 15 23 of stone content flow velocity increased with 0 15 23 of stone content but decreased at higher values this study aims at further understanding the hydrodynamics of soil erosion and sediment transport behaviors in hillslopes with different stone contents to obtain information for quantifying soil erosion on stony slopes

effect of tree thinning and skidding trails on hydrological connectivity in two japanese forest catchments abstract land use composition and patterns influence the hydrological response in mountainous and forest catchments in plantation forest management operations fmo modify the spatial and temporal dynamics of overland flow processes however we found a gap in the literature focussed on modelling hydrological connectivity hc in plantation forest under different fmo in this study we simulated hc in two steep paired forest subcatchments k2 and k3 33 2 ha composed of japanese cypress chamaecyparis obtusa endl and japanese cedar cryptomeria japonica d don plantations 59 of the total area against a tree thinning intensity of 50 at different time additionally construction of new skidding trails and vegetation recovery was simulated on five thinning based scenarios that covered a 40 month test period july 2010 october 2013 as a future scenario six check dams located in the main streams were proposed to reduce sediment and radionuclide delivery an updated version of borselli s index of runoff and sediment connectivity was run using the d infinity flow accumulation algorithm and exploiting three 0 5 m resolution digital elevation models on the basis of the pre fmo scenario hc increased at catchment scale owing to tree thinning and the new skidding trails this change was more noticeable within the area affected by the fmo where hc increased by 11 4 and 10 5 in the cypress and cedar plantations in k2 respectively and by 8 8 in the cedar plantation in k3 at hillslope plot and stream scales the evolution in the values of hc was less evident except the increment by 5 4 observed in the streams at k2 after the fmo progressive vegetation recovery after the fmo triggered a slight reduction of connectivity in all compartments of both subcatchments forest roads and especially skidding trails presented the highest values of hc appearing as the most efficient features connecting the different vegetation patches with the stream network the spatial and temporal evolution of hc over the five past scenarios correlated well with the observed changes in runoff yield as well as with the available values of rainfall interception and throughfall before during and after the fmo the simulation of the proposed scenario recommends the construction of check dams as effective landscape features to somewhat reduce hc and thus to decrease the sediment and radionuclide delivery rates from the two subcatchments

factors controlling sediment yield from small intensively cultivated catchments in a temperate humid climate abstract data on sediment yield from 26 small cultivated catchments 10 10 000 ha in central belgium were collected based on sedimentation rates in small flood retention ponds area specific sediment yield varies from 0 4 to 20 6 t ha 1 year 1 for catchments ranging from 7 to 4873 ha various catchment properties were analysed in order to understand this large variation in sediment yield catchment area alone explains 64 of the observed variance in area specific sediment yield although no other parameter could explain more it is concluded that catchment area is not a valid parameter to link with sediment yield overall catchment geomorphology e g presented by the hypsometric integral is much more important in controlling sediment yield the lack of data however made this not very clear a multiple regression model including three morphological catchment properties is a valuable tool to predict total sediment yield t year 1 from catchments in central belgium this model has an efficiency of 0 81 furthermore it was concluded that the within catchment spatial distribution of parameters for instance slope steepness is very important but difficult to obtain one single representative value the use of spatially distributed erosion and sediment delivery models is therefore necessary accurate sediment yield data like the one presented in this study however are needed to validate these models

joint development normal to regional compression during flexural flow folding the lilstock buttress anticline somerset england alpine inversion in the bristol channel basin includes reverse reactivated normal faults with hanging wall buttress anticlines at lilstock beach joint sets in lower jurassic limestone beds cluster about the trend of the hinge of the lilstock buttress anticline in horizontal and gently north dipping beds j3 joints 295 2858 strike are rare while other joint sets indicate an anticlockwise sequence of development in the steeper south dipping beds j3 joints are the most frequent in the vicinity of the reverse reactivated normal fault responsible for the anticline the j3 joints strike parallel to the fold hinge and their poles tilt to the south when bedding is restored to horizontal this southward tilt aims at the direction of s1 for alpine inversion finite element analysis is used to explain the southward tilt of j3 joints that propagate under a local s3 in the direction of s1 for alpine inversion tilted principal stresses are characteristic of limestone shale sequences that are sheared during parallel flexural flow folding shear tractions on the dipping beds generate a tensile stress in the stiffer limestone beds even when remote principal stresses are compressive this situation favors the paradoxical opening of joints in the direction of the regional maximum horizontal stress we conclude that j3 joints propagated during the alpine compression caused the growth of the lilstock buttress anticline q 2001 published by elsevier science ltd

quantitative analysis of factors controlling sediment yield in mountainous watersheds abstract sediment and turbidity are primary causes of impaired river ecosystems remedial action for these impairments requires the identification of their sources and controlling factors this paper examines the combined effects of watershed complexity in terms of land use and physiography on the specific sediment yield of the upper du river watershed 8973 km2 in china the land use composition land use pattern morphometric variables and soil properties of the watershed were calculated at the subwatershed scale and considered to be potentially influential factors because these watershed characteristics are highly codependent a partial least squares regression plsr was used to elucidate the linkages between the specific sediment yield and metrics composed of 19 selected watershed characteristics the first order factors were identified by calculating the variable importance for the projection vip the results revealed that the land use composition and land use pattern exerted the largest effects on the specific sediment yield and explained 65 2 of the variation in the specific sediment yield a set of physiographic indices was also found to have a large effect on the specific sediment yield and explained 17 7 of the observed variation in the specific sediment yield the following are the dominant first order factors of the specific sediment yield at the subwatershed scale the areal percentages of agriculture and forest patch density value of the shannon s diversity index contagion value of the hypsometric integral and saturated soil hydraulic conductivity the watershed size exerted a substantial effect on the sediment delivery ratio sdr the vip values also suggested that the shannon s diversity index contagion and hypsometric integral are important factors in the sdr with a readily available digital spatial database and rapid developments in geographic information system gis technology this practical and simple plsr approach could be applied to a variety of watersheds

spatial and temporal variation of sediment yield in the landscape example of huanghe yellow river regional scale relations between specific sediment yield and drainage basin area in the huanghe basin reveal varying landscape sedimentary dynamics declining specific sediment yield with area is typical of disturbed agricultural areas while increasing yields indicate the remobilization of stored sediment by bank and floodplain erosion along major tributaries using the developed relations areally adjusted sediment yield maps are created over the entire huanghe basin maps of the loess plateau for periods before and after 1970 reveal major changes in sediment yield indicating that land management may have a major effect on sediment dynamics within a short period of time copyright 2008 by the american geophysical union

investigation of the relationship between precipitation extremes and sediment discharge production under extensive land cover change in the chinese loess plateau abstract to quantify the effects of rainfall and catchment characteristics on sediment yield is of essential importance for sustainable land management precipitation extremes are the external cause of the majority of serious soil erosion and suspended sediment yield ssy events in the chinese loess plateau clp which has undergone extensive land use cover change lucc the investigation of the linkage between climate variables and ssy production is crucial to the precise implementation of ecological restoration strategies thereby reducing soil loss in the clp in this study a partial least squares regression plsr approach is used to investigate this issue using 1961 2015 data from 16 main catchments in the clp this period includes the reference period 1961 1979 period i integrated soil conservation project period 1980 1999 period ii and the grain for green program period 2000 2015 period iii the results indicate that the dominant climate factors driving ssy are precipitation extremes including maximum precipitation events heavy precipitation daily precipitation 25 mm consecutive wet days erosive precipitation daily precipitation 12 mm and annual total precipitation the effects of the precipitation extremes on sediment yield generation are stronger in drier catchments the influence of the precipitation extremes on sediment generation can be strengthened by cultivation and weakened by revegetation especially reforestation the climate driven sediment yield decreased by 951 t km 2 yr 1 during period ii and 505 t km 2 yr 1 during period iii in comparison with period i the dominant cause of the sediment yield reduction was lucc with the contribution increasing from 73 in period ii to 92 in period iii this study provides a greater understanding of the effects of climate variation and lucc on sediment yield and is beneficial for better catchment management

multiple fault slip triggered above the 2016 mw 6 4 meinong earthquake in taiwan rapid shortening in convergent mountain belts is often accommodated by slip on faults at multiple levels in upper crust but no geodetic observation of slip at multiple levels within hours of a moderate earthquake has been shown before here we show clear evidence of fault slip within a shallower thrust at 5 10 km depth in sw taiwan triggered by the 2016 mw 6 4 meinong earthquake at 15 20 km depth we constrain the primary coseismic fault slip with kinematic modeling of seismic and geodetic measurements and constrain the triggered slip and fault geometry using synthetic aperture radar interferometry the shallower thrust coincides with a proposed duplex located in a region of high fluid pressure and high interseismic uplift rate and may be sensitive to stress perturbations our results imply that under tectonic conditions such as high background stress level and high fluid pressure a moderate lower crustal earthquake can trigger faults at shallower depth

modified frequency wavenumber algorithm for regional seismograms using filon s quadrature modelling of lg waves in eastern north america summary the main focus of this study is to develop an efficient frequency wavenumber code to synthesize high frequency say 10 hz regional seismograms up to a distance of more than 1000 km in a medium consisting of a large number of crustal layers and investigate effects of regional waveguides on lg waves in this newly developed code the frequency wavenumber response is evaluated by using the filon s quadrature at high frequency and the polynomial approximation of bessei s functions implementing trapezoidal integration at low frequency this has reduced the computation time by several folds compared to the time needed for the trapezoidal integration using this algorithm both broad band seismograms at harvard and short period ectn eastern canadian telemetered network seismograms from 1988 november 25 saguenay earthquake were successfully modelled a moment magnitude of 5 9 was used initially an average waveguide was calibrated to successfully excite the regional pnl and snl waves at hrv its near surface structure constrained by matching the recorded frequency content the crust mantle transition zone was constrained by modelling the strength of the broad band snl waves consisting of sn ssmsnsmssms and ssmssms phases relative to the initial pnl waves the model was modified to consist of thin layers with an alternating high and low velocity distribution to match the high frequency ectn lg waves observed from 300 to 600 km away in addition the effect of a near surface irregular receiver structure on the duration of lg waves was also investigated by convolving its response with the regional lg seismograms initial study suggests this method as viable for modelling the entire lg waves including the coda numerical studies suggest that the shapes and peak amplitudes on lg seismograms depend more strongly on the source depth anelasticity and crustal waveguide than do the pnl seismograms

effects of lithology and geomorphology on sediment yield in karst mountainous catchments abstract due to the characteristics of the lithology and the complexity of the geomorphology the karst areas of southwest china are experiencing severe soil erosion knowledge of the effects of lithology and geomorphology on sediment yield are therefore essential for developing measures to effectively control sediment delivery in this region the objective of this study was to investigate the relative importance of lithological and geomorphological factors for sediment yield in 40 selected karst mountainous catchments in southwest china because of the high co dependence of these variables a partial least squares regression plsr model was used to explore the quantitative relationships between annual sediment yield and 30 lithological and geomorphological factors results showed that the lithology and geomorphology were critically important to annual sediment yield and could explain 65 9 of the total variance in sediment yield the dominant lithological and geomorphological factors controlling annual sediment yield were karst coverage drainage density basin relief plane curvature elevation maximum elevation average slope dolomite coverage relative relief and catchment area this importance or these contributions of lithological and geomorphological factors to annual sediment yield provides a good reference for selecting key factors when developing soil erosion models this study yields a greater understanding of the influences of lithology and geomorphology on sediment yield and is helpful for better catchment management in karst regions

research paperseffect of stone content on water flow velocity over loess slope frozen soil soils in high altitude or latitude regions are commonly rich in stone fragments which are frequently frozen the hydrodynamics of water flow over frozen stony slopes must be investigated to understand soil erosion and sediment transportation the objective of this laboratory experiments was to measure water flow velocity over frozen slopes with different stone contents by using electrolyte trace method the experiments were performed under slope gradients of 5 10 15 and 20 flow discharge rates of 1 2 4 and 8 l min and stone contents of 0 10 20 and 50 on mass basis nine equidistant sensors were used to measure flow velocity along flume from the top of the slope results indicated that stone content significantly affected flow velocity under increasing slope gradient the increase in stone content rapidly reduced the flow velocity the flow velocities over frozen slopes were 1 21 to 1 30 times of those over non frozen slopes under different slope gradients and flow rates when the stone content increased from 0 to 20 proportions gradually decreased from 52 to 25 and 13 additionally flow velocities over frozen and non frozen soil slopes became gradually similar with increasing stone content this study will help elucidate the hydrodynamics soil erosion and sediment transport behaviors of frozen or partially unfrozen hillslopes with different stone contents

coseismic deformation of the 2010 jiashian taiwan earthquake and implications for fault activities in southwestern taiwan abstract the march 04 2010 jiashian taiwan earthquake mw 6 4 ruptured an unknown fault at depth in southwestern taiwan the main shock initiated near the town of liuquei at 23 km depth and the rupture propagated westward measurements of coseismic displacements from taiwan continuous gps array indicate horizontal displacements of 5 27 mm in the nw sw directions to the west of the epicenter while horizontal movements to the east of the epicenter are absent the gps vertical displacements show an uplift motion of about 5 25 mm near the epicenter in contrast to a small movement of about 5 10 mm observed in the far field gps sites we use coseismic gps displacements and an elastic half space dislocation model to invert for fault geometries and coseismic slip distribution associated with the jiashian earthquake our preferred model exhibits 0 05 0 1 m of reverse slip and 0 04 m of left lateral slip on a n324 trending fault with dip of 40 to ne consistent with the earthquake focal mechanisms from bats usgs neic and global cmt the highest slip of 0 12 m mainly occurs to the west of the epicenter at a depth range of 15 20 km given the rigidity modulus of 60 gpa the geodetic moment is 4 95 1018 n m equivalent to a mw 6 4 earthquake and consistent with the seismic moment estimated from seismic waveform inversion additionally we notice that the mainshock rupture area is surrounded by high seismicity between 1991 and 2007 suggesting that the jiashian earthquake may be triggered by the high stress concentration in the vicinity the calculated coulomb stress changes on nearby fault systems imparted by the coseismic slip suggest that the jiashian earthquake may encourage failures on the chukou fault and inhibit ruptures on the hsinhua fault however the coulomb stress changes are more complicated on the chaochou fault and chishan fault with both positive and negative stress changes

australia s southern margin a product of oblique extension abstract recently developed detachment models of continental margin formation interpret the southern margin of australia to have formed when the lower plate australian margin was pulled out from beneath the upper plate antarctic margin data now available and summarised in this paper point very strongly to a generally nw se direction of initial continental extension for the southern margin in contrast to the widely held picture of simple n s rifting the evidence for this extension direction comes from the analysis of deep seismic data acquired by the bureau of mineral resources in 1986 in the central great australian bight gab the gravity field of the gab seismic and magnetic basement structures in the eyre sub basin polda trough ceduna depocentre and duntroon basin and from the analysis of the magnetic seafloor spreading anomalies produced during the slow first phase of drifting between australia and antarctica further it is now believed that the formation of the southern margin of australia can be described in terms of three phases of continental extension el to e3 and two phases of drifting d1 and d2 in summary these phases were as follows 1 e1 approximately 300 km of late jurassic or older to early cretaceous nw se oriented extension in the gab with strike slip motion in the nascent otway basin and along the tasmanian margin 2 e2 120 km of early cretaceous nne ssw oriented extension which formed the basins of southeastern australia otway bass gippsland and which probably produced a structural overprinting in the gab basin 3 e3 d1 minor continental extension and the first 500 km of slow drift between australia and antarctica on an azimuth of 165 wrenching on the tasmanian margin 4 d2 2600 km of fast drifting between australia and antarctica on a n s azimuth

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

joint vp and vs tomography of taiwan implications for subduction collision orogeny abstract the taiwan orogen sitting at the pre rifted eurasian margin and bracketed by two sub orthogonal subduction systems is subject to complicated geotectonics motivating numerous seismic tomographic studies in local and regional scale most of them obtained p wave velocities vp or with vp vs ratio jointly but few were for s wave velocities vs with unprecedented amount of s wave data in this study a new set of well tuned vp vs and vp vs models were determined by an elaborate joint inversion scheme integrating the data of p and s wave travel times s p times and the borehole logging data for near surface correction into one system this allowed us to revisit the subduction collision process in detail by comparing vp vs and vp vs ratio simultaneously with enhanced slab imaging of philippine sea plate psp under northeast taiwan we are able to discriminate the plausible missing luzon forearc basement along the plate boundary and propose a skateboarding edge model in which the westernmost psp rides on the east subducted forearc basement and subducts northward underneath the eurasian lithosphere the underlain forearc basement along with the psp subduction then results in the anomalous shallow double seismic zone observed only near taiwan island meanwhile at around 121 e the north subducting psp seems dipping west to collide with the deep eurasian lithosphere shaping an irregular corner wedge structure in addition we evaluate our model with previous ones by waveform modeling approach and show the current performance of travel time tomography in taiwan region

basin evolution in western newfoundland new insights from hydrocarbon exploration the humber zone is the most external zone of the appalachian orogen in western newfoundland it records multiphase deformation of the cambrian ordovician passive margin and of the ordovician to devonian foreland basins by the taconian salinian and acadian orogenic events the recent phase of exploration drilling has provided new evidence for structural stratigraphic reservoir and source rock maturation models of western newfoundland the first well port au port 1 supported the hypothesis that the round head thrust had an earlier extensional history prior to the acadian compressional inversion that created the present day structural high of the port au port peninsula the well tested a small anticline formed in a footwall shortcut fault of the round head thrust the second well long point m 16 was drilled at the northern tip of long point to test a triangle zone identified by previous workers this well demonstrates that the frontal monocline at the western edge of the triangle zone is elevated by a stack of imbricate thrusts composed of rocks of the taconian allochthon and compressional basement involved faults that have uplifted the cambrian ordovician carbonate platform the structural model developed in the port au port area with the aid of these wells has been extended throughout the humber zone in western newfoundland changes in structural style illustrated by regional cross sections suggest that prospective trap geometries are only developed in the southern and central parts of the region the reservoir model proposed invokes exposure and karsting of the footwalls of extensional faults formed as the carbonate platform collapsed during a middle ordovician hiatus the st george unconformity structural relief became more pronounced as extensional collapse continued through the middle ordovician begin page 394 these structurally high fault footwalls became the foci for dolomitizing and mineralizing fluids that used major faults as fluid conduits during the devonian fluids deposited sulphide ores and created zebra and sparry dolomite and some sucrosic hydrothermal dolomites in the st george group and the table point formation the reservoir model maturity and source rock data and the structural models have been combined with seismic and onshore surface geology this enables the prospectivity of the western newfoundland cambrian ordovician play trend to be evaluated for further exploration

quantifying cretaceous cenozoic exhumation in the otway basin southeastern australia using sonic transit time data implications for conventional and unconventional hydrocarbon prospectivity in prospective basins affected by exhumation uncertainty commonly exists regarding the maximum burial depths of source reservoir and seal horizons one such basin is the otway basin an important gas province in southeastern australia which has witnessed several exhumation events here we present estimates of net exhumation magnitudes for 110 onshore and offshore petroleum wells based on the sonic transit time analyses of lower cretaceous fluvial shales our results show significant post albian net exhumation in the eastern onshore otway basin 1500 m 4920 ft and a generally minor net exhumation 200 m 655 ft elsewhere in the otway basin consistent with estimates based on thermal history data the distribution of net exhumation magnitudes in relation to mid cretaceous and neogene compressional structures indicates that exhumation was dominantly controlled by short wavelength basin inversion driven by plate boundary forces deeper burial coupled with high geothermal gradients in the onshore eastern otway basin and along the northern basin margin during the early cretaceous have rendered lower cretaceous source rocks mostly overmature with any remaining hydrocarbons from the initial charge likely to be trapped in tightly compacted reservoirs and or secondary fracture related porosity however the embrittlement of these reservoirs during their deeper burial may present opportunities for the development of low permeability plays through hydraulic fracturing where smectite clay minerals are illitized source rocks at near maximum burial at present day are at temperatures suitable for gas generation with key controls on prospectivity in these areas including the sealing potential of faulted traps and the relationship between charge and trap development

spatially distributed erosion and sediment yield modeling in the upper indus river basin 1 spatially distributed erosion rates and sediment yields are predicted in the mountainous upper indus river basin with coupled models of erosion and sediment delivery potential erosion rates are calculated with the thornes model in combination with a surface runoff model sediment delivery ratios sdrs are hypothesized to be a function of travel time of surface runoff from catchment cells to the nearest downstream channel modeled monthly erosion rates for the upper indus river basin indicate that 87 of the annual gross erosion takes place in the three summer months the erosion risk map suggests that the areas with the greatest erosion potential are concentrated in subbasins with high relief and a substantial proportion of glacierized area lower erosion rates can be explained by the arid climate and low relief on the tibetan plateau and by the dense vegetation and lower relief in the lower monsoon subregion high erosion rates 1 0 mm a 1 occur over 66 4 of the basin area the model predicts an average annual erosion rate of 3 2 mm a 1 or 868 mt a 1 which is approximately 4 5 times the long term observed annual sediment yield of the basin the predicted annual basin sediment yield is 244 mt a 1 which compares reasonably well to the measured value of 195 1 mt a 1 the overall sediment delivery ratio in the basin is calculated as 0 28 model results indicate that higher delivery ratios sdr 0 6 are found in 18 of the basin area mostly located in the high relief subbasins the sediment delivery ratio is lower than 0 2 in 70 of the basin area the indus subbasins generally show an increase of sediment delivery ratio with basin area model evaluation based on accuracy statistics suggest very good to satisfactory performance ratings for predicted sediment yields the presented modeling framework requires relatively few data all of which can be derived from global data sets it therefore can be used to predict erosion and sediment yield in other ungaged or poorly gaged drainage basins

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

the influence of a reverse reactivated normal fault on natural fracture geometries and relative chronologies at castle cove otway basin abstract despite the ubiquity of normal faults that have undergone compressional inversion documentation of the structural history of natural fractures around these structures is limited in this paper we investigate the geometries and relative chronologies of natural fractures adjacent to a reverse reactivated normal fault the castle cove fault in the otway basin southeast australia local variations in strain resulted in greater deformation within the fault damage zone closer to the fault structural mapping within the damage zone reveals a complex tectonic history recording both regional and local perturbations in stress and a total of 11 fracture sets were identified with three sets geometrically related to the castle cove fault the remaining fracture sets formed in response to local stresses at castle cove rifting in the late cretaceous resulted in normal movement of the castle cove fault and associated rollover folding and the formation of the largest fracture set reverse reactivation of the fault and associated anticlinal folding occurred during late miocene to pliocene compression rollover folding may have provided structural traps if seals were not breached by fractures however anticlinal folding likely post dated the main episodes of hydrocarbon generation and migration in the region this study highlights the need to conduct careful reconstruction of the structural histories of fault zones that experienced complex reactivation histories when attempting to define off fault fluid flow properties

joints in the mesozoic sediments around the bristol channel basin abstract analysis has been carried out at four locations on the edges of the bristol channel basin to illustrate the later phases of deformation of a sedimentary basin and to illustrate the control on joint patterns of subtle changes in the stress system the characteristics of the joints are described and influences on joints are determined including the roles of faults folds and beds there is a low coefficient of correlation between joint spacing and bed thickness except in very thin limestone beds which have a high density of joints the lengths and spacings of earlier joint phases are usually greater than those of later phases later joints normally abut against earlier joints the joints abut the latest faults but are not displaced by them so the joints post date the main alpine contraction the joints formed in five main phases during reduction of the alpine stresses phase 1 joints are sub parallel to the regional compression direction 160 180 phase 2 joints are perturbed by faults often curving towards points of stress concentrations along the faults phase 3 joints are sub parallel to the earlier e w striking fold axes phase 4 joints are cross joints and phase 5 joints form polygonal patterns within joint bound blocks phases 2 and 3 do not occur in the absence of faults and folds and correspond with a reduction in horizontal compression and an increase in the importance of local factors phases 4 and 5 occur at all locations

fracture initiation development and reactivation in folded sedimentary rocks at raplee ridge ut abstract fractures at raplee ridge a 14 km long monoclinal fold of pennsylvanian sedimentary rock in southeast utah are examined to determine their sequential development and to explain the mechanical relationships among the three primary fracture sets and the fold folding is attributed to slip on an unexposed thrust fault of laramide age fracture orientations were measured at 98 sites and fracture patterns were mapped at 8 sites on two sandstone and two limestone units of the rico formation revealing at least four stages of fracture formation stages 1 and 2 occurred pre folding and are defined respectively by e w trending fracture set i and n s trending fracture set ii set i fractures are characterized by a unimodal distribution of attitudes an intermediately developed outcrop pattern and continuous linear traces on bedding surfaces set ii fractures have a greater dispersion of orientations and are poorly to intermediately developed abutting relationships confirm that set i fractures are older than set ii stage 3 occurred during folding when nw se trending set iii fractures initiated both from isolated flaws and as wing cracks due to right lateral shearing along reactivated set i fractures set iii fractures increase in density as the fore limb dip increases from 10 to 30 later stages of deformation are characterized by the formation of fracture subsets iv and v structurally associated with fore limb dips greater than 30 fracture sets i and ii are found throughout the surrounding monument upwarp and are attributed to that structure whereas set iii is attributed to local stresses induced by monoclinal folding and or thrust faulting

measurement of rill and ephemeral gully flow velocities and their model expression affected by flow rate and slope gradient abstract water flow velocities in rill and ephemeral gully are useful for estimating hydrodynamics in the study on soil erosion laboratory experiments were conducted to measure erosive rill and ephemeral gully flow velocities including nine unit width flow rates of 0 17 0 33 0 67 1 33 2 67 5 33 10 67 21 33 and 42 67 10 3 m2 s 1 and five slope gradients of 8 7 17 6 26 8 36 4 and 46 6 on sandpaper slope glued with silt loam soil materials to imitate fixed rill and ephemeral gully beds using an electrolyte tracer method the flow velocities measured in this research ranged from 0 31 to 3 34 m s 1 for sediment free water flow the flow velocity fitted well with unit width flow rate and slope gradient by a power function yielding an improved model with higher coefficient of determination than that related flow velocity to flow rate alone the improved model is applicable for flow velocity and soil erosion predictions

the response of soil erosion and sediment export to land use change in four areas of europe the importance of landscape pattern the response of erosion and sediment export to past land use change has been studied in four agricultural areas of europe three of these areas were subject to land abandonment or de intensification and one to intensification of land use practices erosion and sediment yield were modeled using the watem sedem model which combines the rusle equation with a sediment routing algorithm spatial relationships between the rusle c factor i e land use and other erosion and sediment export determining factors slope soil erodibility and distance to rivers were investigated as these account for non linearity in the response of erosion and sediment export to land use change erosion and sediment export have decreased enormously in the de intensified areas but slightly increased in the intensively cultivated area the spatial pattern of land use change in relation to other erosion and sediment export determining factors appears to have a large impact on the response of soil erosion and sediment export to land use change that the drivers of abandonment of arable land and erosion coincide indicates that de intensification leads to a more favourable landscape pattern with respect to reduction of erosion and sediment export this mechanism applies not only within the study areas but also among the european study areas where the process of intensification of some areas and de intensification of others might result in an overall decrease of erosion and sediment yield through time c 2007 elsevier b v all rights reserved

inferred fault geometry and slip distribution of the 2010 jiashian taiwan earthquake is consistent with a thick skinned deformation model abstract we invert measurements of coseismic displacements from 139 continuously recorded gps sites from the 2010 jiashian taiwan earthquake to solve for fault geometry and slip distribution using an elastic uniform stress drop inversion the earthquake occurred at a depth of 23 km in an area between the western foothills fold and thrust belt and the crystalline high mountains of the central range providing an opportunity to examine the deep fault structure under taiwan the inferred rupture plane is oblique to the prominent orientation of thrust faults and parallel to several previously recognized nw striking transfer zones that appear to connect stepping thrusts we find that a fault striking 318 344 with dip of 26 41 fits the observations well with oblique reverse sinistral slip under a low stress drop of about 0 5 mpa the derived geodetic moment of 2 92 10 18 n m is equivalent to a m w 6 24 earthquake coseismic slip is largely concentrated within a circular patch with a 10 km radius at the depth between 10 and 24 km and maximum slip of 190 mm we suggest this earthquake ruptured the nw striking chishan transfer fault zone which we interpret as a listric ne dipping lateral ramp with oblique slip connecting stepping thrust faults ramps the inferred slip on the lateral ramp is considerably deeper than the 7 15 km deep detachment identified in previous studies of western taiwan we infer an active basal detachment under western taiwan at a depth of at least 20 23 km based on these inversion results the earthquake may have nucleated at the base of the lateral ramp near the intersection with the basal detachment coulomb stress change calculations suggest that this earthquake moved several ne striking active thrust faults in western taiwan nearer to failure

geometric models of listric normal faults and rollover folds existing geometric models allow master fault shapes to be constructed given the shape and heave or displacement of a deformed marker horizon in the hanging wall these models assist in projecting normal faults to depth where the fault geometry is poorly constrained by available seismic data currently it is unclear which model best predicts the actual relation between rollover and fault geometries to address this deficiency the relative accuracies of the constant heave constant displacement constant bed length slip line and inclined shear constructions are evaluated using clay model analogs and seismic examples each of the geometric models predicts a different fault shape and depth to detachment for the same rollover shape because different hanging wall deformat on mechanisms are assumed a construction is developed for determining the hanging wall geometry from a known fault geometry this construction is based on the inclined shear model and geometric constraints imposed by material displacement paths viewed from different reference frames fixed to the hanging wall and footwall blocks in clay models the inclined shear antithetic shear greek alpha 20 degrees and slip line constructions produce the best agreement between actual and modeled fault and marker bed shapes in rollovers for subsurface examples the inclined shear model antithetic shear greek alpha 20 40 degrees and the constant displacement model predict fault trajectories that are the most similar to the positions and shapes of the master fault segments interpreted fr m offshore norway and gulf of mexico seismic lines the shear angle required in the inclined shear model can often be estimated from the orientation of minor faults in the hanging wall the shear angle may also be determined through iterative modeling in which the shear angle is systematically varied and the resultant model fault shape is compared to the shape of the shallow segment of the master fault interpreted from the seismic record

stress triggering in thrust and subduction earthquakes and stress interaction between the southern san andreas and nearby thrust and strike slip faults 1 we argue that key features of thrust earthquake triggering inhibition and clustering can be explained by coulomb stress changes which we illustrate by a suite of representative models and by detailed examples whereas slip on surface cutting thrust faults drops the stress in most of the adjacent crust slip on blind thrust faults increases the stress on some nearby zones particularly above the source fault blind thrusts can thus trigger slip on secondary faults at shallow depth and typically produce broadly distributed aftershocks short thrust ruptures are particularly efficient at triggering earthquakes of similar size on adjacent thrust faults we calculate that during a progressive thrust sequence in central california the 1983 mw 6 7 coalinga earthquake brought the subsequent 1983 mw 6 0 nunez and 1985 mw 6 0 kettleman hills ruptures 10 bars and 1 bar closer to coulomb failure the idealized stress change calculations also reconcile the distribution of seismicity accompanying large subduction events in agreement with findings of prior investigations subduction zone ruptures are calculated to promote normal faulting events in the outer rise and to promote thrust faulting events on the periphery of the seismic rupture and its downdip extension these features are evident in aftershocks of the 1957 mw 9 1 aleutian and other large subduction earthquakes we further examine stress changes on the rupture surface imparted by the 1960 mw 9 5 and 1995 mw 8 1 chile earthquakes for which detailed slip models are available calculated coulomb stress increases of 2 20 bars correspond closely to sites of aftershocks and postseismic slip whereas aftershocks are absent where the stress drops by more than 10 bars we also argue that slip on major strike slip systems modulates the stress acting on nearby thrust and strike slip faults we calculate that the 1857 mw 7 9 fort tejon earthquake on the san andreas fault and subsequent interseismic slip brought the coalinga fault 1 bar closer to failure but inhibited failure elsewhere on the coast ranges thrust faults the 1857 earthquake also promoted failure on the white wolf reverse fault by 8 bars which ruptured in the 1952 mw 7 3 kern county shock but inhibited slip on the left lateral garlock fault which has not ruptured since 1857 we thus contend that stress transfer exerts a control on the seismicity of thrust faults across a broad spectrum of spatial and temporal scales

tectonic evolution of the fundy rift basin canada evidence of extension and shortening during passive margin development seismic and field data show that the fundy rift basin of southeastern canada experienced two distinct episodes of deformation during mesozoic time the first episode during middle triassic to early jurassic time was extensional rifting associated with nw se extension reactivated ne trending paleozoic compressional structures as normal faults forming the northwestern boundary faults of the fundy basin displacements on the low angle boundary faults locally exceeded 10 km rifting also reactivated east trending paleozoic compressional structures as oblique slip faults with normal and sinistral strike slip components forming the northern boundary faults of the fundy basin several kilometers of sediments and lava flows filled the basin during rifting the second deformational episode occurred during or after early jurassic time and probably before or during early cretaceous time inversion associated with nw se shortening occurred along all faulted margins of the fundy basin the northwestern boundary faults experienced several kilometers of reverse displacement broad anticlines developed within their hanging walls and the fundy basin acquired its synclinal form the northern boundary faults of the fundy basin became oblique slip faults with reverse and dextral strike slip components gentle synclines tight anticlines and faults with reverse separation deformed the synrift strata near the northern margin of the fundy basin neither collision nor subduction zones existed near the fundy basin during mesozoic time hence we believe that tectonic processes associated with seafloor spreading e g incipient ridge push forces continental resistance to plate motion produced the shortening in the fundy basin shortening occurred during the transition from rifting to drifting as north america separated from northern africa and or during the early stages of drifting as the seafloor spreading centers of the north atlantic propagated northward

reassessing the complexity of the rupture of the 2010 jia shian earthquake mw 6 2 in southwestern taiwan by inverting jointly teleseismic strong motion and cgps data abstract a new interpretation is proposed for the 2010 jia shian earthquake mw 6 2 which occurred on march 4 2010 in southwestern taiwan among the few tens of cgps stations which recorded the mainshock at a distance less than 50 km we identified a few stations displaying horizontal displacements in disagreement with the dominant pattern of horizontal coseismic motion based on this observation we find that a secondary rupture plane explains these peculiar motions and helps improving the modeling of the overall set of cgps stations we also model the teleseismic and strong motion records to refine the rupture model finally we obtain the slip distribution on a two fault model by the joint inversion of all three datasets cgps teleseismic and strong motion the main fault plane is consistent with previous studies it corresponds to a n311 e fault dipping 33 to the ne with left lateral reverse oblique slip likely related to the chishan transfer fault zone ctfz we find that the earthquake started with a sharp slip patch localized at the hypocenter the secondary rupture plane is a n20 e thrust fault related to the lungchuan anticline faulting on the main nw se plane during the jia shian earthquake and stress inversions from previous studies both suggest a direction of maximum horizontal compression oriented ne sw in the area of the earthquake very different from the dominant nw se compression direction in taiwan we propose that such a variation can be related to a stress deviation in the immediate vicinity of the ctfz in a similar way as observed along the san andreas fault in california on the other hand rupture on the secondary fault plane associated with the lungchuan anticline appears to be compatible with the dominant compression in taiwan

seismic slip on an upper plate normal fault during a large subduction megathrust rupture slip during subduction zone earthquakes is often assumed to occur on a single fault analysis of a 2011 chilean earthquake shows that the event was composed of two quakes with megathrust rupture triggering slip in the overriding plate quantification of stress accumulation and release during subduction zone seismic cycles requires an understanding of the distribution of fault slip during earthquakes reconstructions of slip are typically constrained to a single known fault plane yet slip has been shown to occur on multiple faults within the subducting plate1 owing to stress triggering2 resulting in phenomena such as earthquake doublets3 however rapid stress triggering from the plate interface to faults in the overriding plate has not been documented here we analyse seismic data from the magnitude 7 1 araucania earthquake that occurred in the chilean subduction zone in 2011 we find that the earthquake which was reported as a single event in global moment tensor solutions4 5 was instead composed of two ruptures on two separate faults within 12 s a thrust earthquake on the plate interface triggered a second large rupture on a normal fault 30 km away in the overriding plate this configuration of partitioned rupture is consistent with normal faulting mechanisms in the ensuing aftershock sequence we conclude that plate interface rupture can trigger almost instantaneous slip in the overriding plate of a subduction zone this shallow upper plate rupture may be masked from teleseismic data posing a challenge for real time tsunami warning systems

factors controlling specific sediment yield in the upper indus river basin northern pakistan estimates of sediment yield are essential in water resources analysis modelling and engineering in investigations of continental denudation rates and in studies of drainage basin response to changes in climate and land use the availability of high resolution global environmental datasets offers an opportunity to examine the relationships between specific sediment yield sysp and drainage basin attributes in a geographical information system gis environment this study examines sysp at 14 long term gauging stations within the upper indus river basin twenty nine environmental variables were derived from global datasets the majority with a 1 1 km resolution the sysp ranges from 194 to 1302 t km 2 yr 1 for sub basins ranging from 567 to 212 447 km2 the high degree of scatter in sysp is greatly reduced when the stations are divided into three groups upper glacierized sub basins lower monsoon sub basins and the main indus river percentage snow ice cover lcs emerges as the single major land cover control for sysp in the high mountainous upper indus river basin a regression model with percentage snow ice cover lcs as the single independent variable explains 73 4 of the variance in sysp for the whole indus basin a combination of percentage snow ice cover lcs relief and climate variables explains 98 5 of the variance for the upper glacierized sub basins for the lower monsoon region a regression model with only mean annual precipitation p explains 99 4 of the variance along the main indus river a regression model including just basin relief r explains 92 4 of the variance in sysp based on the r2adj and p value statistics the variables used are capable of explaining the majority of variance in the upper indus river basin copyright 2007 john wiley sons ltd

spatial heterogeneity of soil detachment capacity by overland flow at a hillslope with ephemeral gullies on the loess plateau abstract ephemeral gullies are typical erosional landforms and widespread on the chinese loess plateau to better understand the spatial variability in soil detachment capacity dc by overland flow and its influence at a hillslope with an ephemeral gully this study investigates a hillslope on the loess plateau using classical statistics geostatistical analysis and principal component analysis undisturbed soil samples were collected from 202 sites along nine 90 m transects in two completely developed ephemeral gullies and were scoured in a laboratory flume under consistent hydraulic conditions the results indicate that dc varied widely from 0 0004 to 1 25 kg m 2 s 1 with a mean of 0 22 kg m 2 s 1 the coefficient of variation also shows a high variability in dc the ephemeral gullies were divided into four sections uppermost upper middle and lower slopes and dc differed significantly among the four sections a semivariogram of dc indicated a moderate spatial dependence the sampling interval significantly affects the spatial pattern of dc when the sampling interval decreased from 10 to 2 m the nugget variance decreased whereas structured variance spatial dependence and range increased distribution maps of dc derived from kriging interpolation showed that samples in the lower slope position have greater dc than the other positions dc significantly correlates with clay content sand content median soil grain size bulk density cohesion water stable aggregate and litter mass density principal component analysis pca and a minimum data set mds method identified that the median soil grain size bulk density and litter mass density were the major factors affecting the spatial variability in dc

deep seismic images and the tectonic framework of early rifting in the otway basin australian southern margin abstract the otway basin is one of a number of basins formed along australia s southern continental margin during the late jurassic early cretaceous rifting of australia from antarctica it lies on a transitional area of extended lithosphere between the margin to the west where continental separation took place close to the australian craton and the region to the east where separation failed to develop through bass strait but instead switched to the south of tasmania seven agso regional deep seismic profiles recorded during 1992 across onshore parts of the basin provide images of synrift basin bounding faults that dip predominantly towards the continent basin sequences in half graben rift segments at two way times greater than 4 s and mid crustal detachments with ramp and flat geometry at mid crustal levels when combined with industry seismic data trend variations on faults indicate that extensional strain direction varied along the rift system probably locally controlled by pre existing palaeozoic geology but consistent with general north south lithospheric extension basement highs between some of the rift segments are interpreted as accommodation or transfer zones multiple basin bounding faults in some places mirror features within basement and may indicate a component of local strike slip during early rifting the syn rift segments form part of the first stage early cretaceous failed rift system in the otway bass strait region crustal thickness is interpreted to be 31 km 10 3 10 5 s twt near the northern basin margin thinning to about 25 km 9 s twt 40 reduction in thickness of palaeozoic crust seaward of the tartwaup fault zone this fault zone and the timboon fault system farther east are interpreted to be headwall faults landward limit of a late cretaceous second stage rifting system along a lower plate margin which ultimately separated australia from antarctica

aseismic deformation of a fold and thrust belt imaged by synthetic aperture radar interferometry near shahdad southeast iran at depth many fold and thrust belts are composed of a gently dipping basal thrust fault and steeply dipping shallower splay faults that terminate beneath folds at the surface movement on these buried faults is difficult to observe but synthetic aperture radar sar interferometry has imaged slip on at least 600 km 2 of the shahdad basal thrust and splay fault network in southeast iran approximately 70 mm of thrust motion on the 88 dipping shahdad basal thrust occurred 8 30 km to the east of the 14 march 1998 fandoqa earthquake mw 5 6 6 that involved 1 6 m of oblique strike slip and normal slip displacement on a steeply dipping fault that earthquake transferred stress to the shahdad basal thrust and associated splays triggering slip either immediately or in the following six months modeling shows that to produce the observed surface deformation the shahdad faults must have accommodated a nearly complete release of the shear stress increase this could be due to either low friction on the faults or deformation throughout a wedge of material that is everywhere close to failure the anomalously small magnitude of displacement on the shahdad basal thrust and splay faults compared to the area of slip suggests a slip mechanism that is likely aseismic

the combined inversion of seismic and geodetic data for the source process of the 16 october 1999 mw 7 1 hector mine california earthquake we investigate the source process of the m w 7 1 hector mine earthquake by inverting broadband regional and local seismic displacement waveforms com bined with global positioning system gps and synthetic aperture radar interfer ometry insar geodetic measurements we find that the three data sets individually produce remarkably similar slip distributions over a multisegment fault a simulta neous inversion of the three data sets is presented and the sensitivity of the combined inversion to the weighting of the three independent data sets is examined the results indicate that the overall length of the fault that slipped is 42 km with a peak slip of 5 50 m and total scalar seismic moment of 6 8 10 19 n m the majority of slip is located on the western branch of the lavic lake fault to the northwest of the hypo center although the overall rupture is bilateral with appreciable slip on the bullion fault to the southeast some slip is located on an eastern branch of the lavic lake fault an apparent bifurcation which is also evident from aftershock locations the average slip and stress drops are 2 70 1 62 1 60 m and 78 36 and 55 bars for the western lavic lake the eastern lavic lake and bullion faults respectively the results also indicate that the overall rupture process is relatively slow which is char acterized by a several second delay before the onset of significant slip a 1 8 km sec rupture velocity of the primary asperity and long spatially variable dislocation rise times

modern vertical deformation rates and mountain building in taiwan from precise leveling and continuous gps observations 2000 2008 1 to characterize the present day vertical displacement field in the active taiwan orogenic belt 1843 precise leveling and 199 continuous gps measurements from 2000 to 2008 are collected and analyzed in this study vertical velocities derived from the leveling data are placed in a reference frame of the chinese continental margin using continuous gps observations at nearby sites the leveling and gps vertical velocities generally reveal a dome shaped pattern with uplift of 0 2 18 5 mm yr in the interior of the mountain range and subsidence on the flanks of the mountains and coastal plains modern uplift rates in the active fold and thrust belt are generally consistent with geologic uplift rates however present day uplift rates in the central range are faster than the million years averaged exhumation rates the modern subsidence rates are generally consistent with geologic rates except for the rates in western coastal areas due to groundwater pumping present day subsidence in the southern central range and northern coastal range is however inconsistent with long term uplift which may reflect interseismic elastic strain accumulation across faults present day subsidence in northern taiwan occurs in a region of postcollisional orogenic collapse we model the present day and geologic vertical velocities and published gps horizontal velocity data across southern taiwan using a 2 d lithospheric model the model suggests a combined slip rate of 40 mm yr on the frontal thrusts and 45 mm yr on the longitudinal valley fault the model requires an additional source of crustal thickening under the central range to match the observed present day uplift rates

laurentian palaeostress trajectories and ephemeral fracture permeability cambrian eriboll formation sandstones west of the moine thrust zone nw scotland abstract cambrian eriboll formation sandstones of the ardvreck group that crop out west of the moine thrust zone contain joints and quartz filled or quartz lined fractures that resemble cemented joints of the fractures containing quartz five sets strike north nw to wnw ne west and north according to crosscutting relations this is a progression from the oldest to the youngest set sets include opening mode microfractures partly visible in transmitted light as fluid inclusion planes and sharply defined as microveins using sem based cathodoluminescence cl dating the oldest north striking set using inferred quartz accumulation rates fluid inclusions and burial history suggests that these fractures mark a palaeozoic east west least horizontal stress trajectory in laurentia the youngest two sets of porous fractures are associated with faults that cut and postdate the moine thrust zone data indicate that at depth in basins pervasive fracture systems arising from discrete loading events are ephemeral owing to fracture porosity destruction by cementation

analysis of factors determining sediment yield variability in the highlands of northern ethiopia in many developing countries sustainable land management and water resources development are threatened by soil erosion and sediment related problems in response to such threats there is an urgent need for improved catchment based erosion control and sediment management strategies the design and implementation of such strategies require data on erosion rates and understanding of the factors that control the delivery of sediment through the catchment system in this study reservoir sedimentation and corresponding catchment attribute data were used to investigate the major factors controlling sediment yield variability in a mountainous dryland region of northern ethiopia sediment yield data were acquired for representative 11 catchments above reservoirs geomorphological and anthropogenic catchment attributes were extracted for each reservoir from different sources including digital elevation models satellite images and field surveys different statistical analyses such as pearson s correlation principal components and multiple regression were implemented to analyze the relationship between sediment yield and catchment characteristics and to determine the major factors controlling the variability of sediment yield the results show that terrain form gully erosion surface lithology and land cover explain most of the variability in sediment yield among the catchments the implications of the results for relevant management intervention targeted at ameliorating the major causative factors of erosion are also outlined

sedimentary basin inversion and intra plate shortening abstract sedimentary basin inversion the shortening of formerly extensional basins is accommodated mainly by compressional reactivation of extant faults and fractures across a wide range of scales as such inversion is a large scale manifestation of byerlee friction the dynamic criterion for fault reactivation governing the effective shear strength of the shallow crust basin inversion generates distinctive deformational architecture and it is implicated strongly in sedimentary basin exhumation as a principal source of horizontal stress inversion drives significant sedimentary porosity reduction and resultant fluid flow upper crustal deformation is critically dependent on fluid overpressure i e pore fluid pressures greater than would be calculated from a hydrostatic gradient and perhaps more than in any other tectonic setting overpressures are potentially large during sedimentary basin inversion this review therefore includes discussion of the role of fluid overpressure in inversion and the evidence for it collectively inversion has profound implications good and bad for the prospectivity of many petroliferous sedimentary basins thus recognizing the evidence for basin inversion quantifying its magnitude and understanding the mechanisms that accommodate inversion and other phenomena affected by it have become essential components of the basin analyst s remit

change of tectono stratigraphic regime in the australian plate during the 99 ma mid cretaceous and 43 ma mid eocene swerves of the pacific the clockwise bend at 99 ma mid cretaceous in linear volcanic chains in the tropical pacific coincides with a change from pre 99 ma head on chilean type subduction of the pacific plate beneath eastern gondwana to 99 43 ma sinistral oblique mariana type subduction and strike slip breakup by simple sea floor spreading between australia and antarctica and by backarc spreading in the southwest pacific the 99 ma breakup of australia from antarctica is documented by a mid cretaceous unconformity this tectono stratigraphic change founded modern australia with a mountain chain along an upper plate margin in the east and lowlands on the lower plate margin in the south the counterclockwise bend at 43 ma mid eocene the emperor hawaiian bend coincides with the onset of structure in the challenger rift of new zealand the eromanga cooper basin of central australia and the oil shale grabens of coastal queensland

source complexity of the 4 march 2010 jiashian taiwan earthquake determined by joint inversion of teleseismic and near field data abstract the jiashian earthquake m l 6 4 occurred on 4 march 2010 it was the largest inland event in southern taiwan of 2010 the mainshock location was unexpected since it occurred in an area with relatively low background seismicity in addition reports of earthquake focal mechanisms do not fit with any known active fault geometry in order to understand the origin of this earthquake especially its rupture process we perform a joint source inversion by using teleseismic body wave gps coseismic displacements and near field ground motion data in this study we considered a northwest southeast trending fault with a northeast dip retrieved from gps coseismic data and aftershocks distribution to analyze the detailed slip distribution in space and time we used near field 3d green s functions provided by spectral element method and a full time space inversion technique we find a complex rupture process with several slip patches distributed inside two main asperities the slip map reveals a mean slip of 12 9 cm for a maximum slip of 27 3 cm leading to a m w 6 47 for this event the rupture initiates in the deepest portion of the fault at 20 km depth and propagated upward up to 2 km depth to form the two asperities the source time function of this event revealed two pulses corresponding to the two asperities for a total duration time of about 16 s most aftershocks occurred near the upper boundary of the deepest asperity while no aftershocks are located close to the shallowest one we infer that the locations of these slip patches are related to the surrounding fault systems that may have restricted the rupture propagation during the earthquake

joint inversion of seismic and geodetic data for the source of the 2010 march 4 mw 6 3 jia shian sw taiwan earthquake

inversion of strong ground motion and teleseismic waveform data for the fault rupture history of the 1979 imperial valley california earthquake a least squares point by point inversion of strong ground motion and teleseismic body waves is used to infer the fault rupture history of the 1979 imperial valley california earthquake the imperial fault is represented by a plane embedded in a half space where the elastic properties vary with depth the inversion yields both the spatial and temporal variations in dislocation on the fault plane for both right lateral strike slip and normal dip slip components of motion inversions are run for different fault dips and for both constant and variable rupture velocity models effects of different data sets are also investigated inversions are compared which use the strong ground motions alone the teleseismic body waves alone and simultaneously the strong ground motion and teleseismic records the inversions are stabilized by adding both smoothing and positivity constraints the moment is estimated to be 5 0 10 25 dyne cm and the fault dip 90 5 dislocation in the hypocentral region south of the united states mexican border is relatively small and almost dies out near the border dislocation then increases sharply north of the border to a maximum of about 2 m under interstate 8 dipslip motion is minor compared to strike slip motion and is concentrated in the sediments the best fitting constant rupture velocity is 80 per cent of the local shear wave velocity however there is a suggestion that the rupture front accelerated from the hypocenter northward the 1979 imperial valley earthquake can be characterized as a magnitude 5 earthquake at the hypocenter which then grew into or triggered a magnitude 6 earthquake north of the border

a note on fault reactivation reactivation of existing faults whose normal lies in the 1 3 plane of a stress field with effective principal compressive stresses 1 2 3 is considered for the simplest frictional failure criterion n n p where and n are respectively the shear and normal stresses to the existing fault p is the fluid pressure and is the static friction for a plane oriented at to 1 the stress ratio for reactivation is 1 3 1 cot 1 tan this ratio has a minimum positive value at the optimum angle for reactivation given by 12tan 1 1 but reaches infinity when 2 beyond which 3 0 is a necessary condition for reactivation an important consequence is that for typical rock friction coefficients it is unlikely that normal faults will be reactivated as high angle reverse faults or thrusts as low angle normal faults unless the effective least principal stress is tensile

structural style and evolution of inversion structures of horus field alamein basin northern western desert of egypt abstract high quality three dimensional 3d seismic reflection and borehole data are used to characterize in detail the structural style and evolution of inversion structures in horus oil field this field lies in the central part of alamein basin northern western desert of egypt in the hanging wall of a major jurassic early cretaceous normal fault this fault delineates the northwestern margin of the basin and extends in an ene wsw direction bounding a half graben trough in its hanging wall this trough had continued subsidence during early cretaceous time with depositional thickening of the lower cretaceous alam el bueib formation fault displacement had ceased near the top of barremian level aptian lower senonian seismically traced levels show a major ne plunging asymmetrical anticline overlying the jurassic barremian half graben this anticline is sub parallel to the inherited jurassic rifting fault at shallower cretaceous levels this fault is replaced by a set of wnw ese trending en echelon faults of considerable displacements which probably indicates a strike slip component of deformation these faults display normal separation on all displaced stratigraphic levels and tip upwards in the upper part of the upper cretaceous succession this marks a considerable change in the tectonic mode of the area nw se extensional faults were developed perpendicular to the fold axis dissecting the anticline into several blocks entrapping hydrocarbons detailed seismic structural analysis of growth strata indicates that the fold initiated in early senonian time was associated with the inversion of the earlier jurassic barremian half graben this basin inversion is attributed to the syrian arc event that dominated north africa during the late cretaceous time and continued through to the early miocene low fold amplitude coupled with normal displacements on the deep seated ene wsw trending jurassic barremian fault indicate a mild phase of positive inversion the upper senonian eocene stratigraphic sequences increased in thickness in the back troughs that were associated with basin inversion