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

numerical modeling of crustal block and fault dynamics earthquakes and slip rates in the tibet himalayan region the tibetan plateau and himalayans have resulted from the continuous indian and eurasian plate convergence following their initial collision about 55 million years ago earthquakes in the region occur mainly in response to the crustal motion and stress localization associated with this convergence to understand the basic features of the crustal motion and seismicity in the tibet himalayan region we develop a numerical model of block and fault dynamics the model structure is composed of six major upper crustal blocks separated by fault planes these blocks are assumed to be perfectly rigid and move as a consequence of the indian plate push and of a flow of the lower crust deformations take place along the fault planes separating the blocks the interaction of the blocks along the fault planes is visco elastic as long as the ratio of the shear stress to the difference between the pore pressure and normal stress remains below a critical strength level when the critical level is exceeded in some part of a fault plane an earthquake stress drop occurs causing also failures in adjacent parts of the fault plane the stress drop affected parts of the fault plane enter in a state of creep immediately after the earthquake and the creep lasts until the stress falls below a certain level we develop several sets of numerical experiments to analyze the earthquake clustering frequency to magnitude relationships earthquake focal mechanisms and fault slip rates in the model large events in the numerical experiments cluster on the fault segments associated with the himalayan frontal thrust as well as at some internal faults of the tibetan plateau the clustering of earthquakes on a given fault is a consequence of the dynamics of the regional fault system rather than that of the fault only we show that variations in the relationship of magnitude to frequency of the events are associated with changes in the motion of the upper crustal blocks and depend on the rheological properties of fault plane zones the focal mechanisms of model events are found to be consistent with that of earthquakes in the region the synthetic moment rate captures the observed rate of seismic moment release we demonstrate in the model that the present crustal motion in the region is indeed governed by the north northeastern movement of india toward eurasia and the movement of the lower crust variations in the rheological properties of fault plane zones and or in the motion of the lower crust influence rates of the crustal block displacements and slips at the faults separating the blocks this can explain the discrepancies in estimates of slip rates over short and long time scales at major faults in the region

sea level reconstructions from the peri vocontian zone south east france point to valanginian glacio eustasy the valanginian is a period of global environmental change as illustrated by sedimentary palaeontological geochemical and climatic perturbations a production crisis in most of the carbonate platforms suggests important changes in palaeoenvironmental conditions during the same time interval a major positive excursion in 13c the weissert event suggests perturbations of the carbon cycle from the latest early valanginian to the early hauterivian in order to better understand the link between these changes sea level fluctuations have been reconstructed in detail from the middle berriasian to the earliest hauterivian sections from the peri vocontian zone south east france have been investigated because of the good quality of outcrops on the carbonate platforms their margins and in the vocontian basin sections ranging from the most proximal zone swiss jura to the basin were interpreted in terms of sequence stratigraphy and cyclostratigraphy and correlated at high resolutions using the identified small medium and large scale sequences as well as depositional geometries sea level fluctuations were reconstructed two main trends are evidenced during the studied interval i the peak amplitude magnitude of the sea level fluctuations increased gradually from the middle berriasian to the early valanginian and reached a maximum more than 50 m from the middle early valanginian to the valanginian hauterivian boundary and ii sea level variations were quite symmetrical during the late berriasian slightly asymmetrical during the early valanginian and strongly asymmetrical fast sea level rise slow fall from the latest early valanginian to the earliest hauterivian moreover three orders of sea level fluctuations were recognized in the sedimentary rocks of the peri vocontian zone platform basin correlations and cyclostratigraphic interpretations of the basinal sections evidence an astronomical control on the sea level variations mainly by the two eccentricity cycles of 100 and 400 kyr the increase in the amplitude of the sea level fluctuations and their change from symmetrical to asymmetrical can be related to the onset of a major cooling event in the early valanginian fast transgressions followed by slower regressions would correspond to waxing and waning of high latitudinal ice during most of the valanginian especially from the latest early valanginian to the latest late valanginian glacio eustatic sea level fluctuations in tune with the 100 and 400 kyr eccentricity cycles are in agreement with glaciations during the valanginian

unravelling the depositional origins and diagenetic alteration of carbonate breccias carbonate breccias dissociated from their platform top counterparts are little studied despite their potential to reveal the nature of past shallow water carbonate systems and the sequential alteration of such systems a petrographic and stable isotopic study allowed evaluation of the sedimentological and diagenetic variability of the cenozoic batu gading limestone breccia of borneo sixteen lithofacies representing six facies groups have been identified mainly from the breccia clast on the basis of shared textural and compositional features clasts of the breccia are representative of shallow carbonate platform top and associated flank to basinal deposits dominant inputs are from rocky karstic shorelines or localised seagrass environments coral patch reef and larger foraminiferal rich deposits early pre brecciation alteration including micritisation rare dissolution of bioclasts minor syntaxial overgrowth cementation pervasive neomorphism and calcitisation of bioclasts and matrix was mainly associated with marine fluids in a near surface to shallow burial environment the final stages of pre brecciation diagenesis include mechanical compaction and cementation of open porosity in a shallow to moderate depth burial environment post brecciation diagenesis took place at increasingly moderate to deep burial depths under the influence of dominantly marine burial fluids extensive compaction circum clast dissolution seams and stylolites have resulted in a tightly fitted breccia fabric with some development of fractures and calcite cements a degree of facies specific controls are evident for the pre brecciation diagenesis pervasive mineralogical stabilisation and cementation have however led to a broad similarity of diagenetic features in the breccia clasts thereby effectively preserving depositional features of near original platform top and margin environments there is little intra clast alteration overprint associated with subsequent clast reworking and post brecciation diagenesis the diagenetic and to an extent depositional and clast characteristics of the batu gading deposits are diagnostic of breccia origins the predominance of early and pervasive stabilisation of calcitic components pervasive compaction resulting in a fitted texture and paucity of meteoric dissolution or cementation effects are collectively all indicators of slope deposition and lithification these features are comparable with other regional and global examples of submarine slope breccias and consistent with the prior interpretation that the carbonate platform at batu gading developed in a rotating wedge top basin wannier 2009 the results of this study along with regional analogues suggest the potential for reworked carbonates debris in slope settings to be a viable way of investigating carbonate platform variability and their subsequent alteration in the absence of preserved platform top or margin deposits

coarse carbonate breccias as a result of water wave cyclic loading uppermost jurassic south east basin france in the uppermost jurassic of the central part of the south east basin of france an association of lime mudstone beds calcarenite beds and coarse carbonate breccia bodies form an informal stratigraphical unit called the barre tithonique in the barre tithonique gradual transitions from lime mudstone or calcarenite to breccia show different stages of deformation leading to progressive brecciation of the original lithologies the study of the breccia facies and the observed gradual transitions as a whole document a new early diagenetic process in carbonate environments resulting from water wave and seabed interaction water wave induced brecciation and its abundance in the barre tithonique indicate that sea seabed interaction was significant comparison with modern studies of the mechanics of wave seabed interaction suggests that water depth was less than 200 m it is demonstrated that sedimentary features such as channel like structures previously interpreted as being the result of erosion and deposition of mud flows were in fact produced by wave induced in situ reworking of lime mud without any significant unidirectional flow or gravity induced displacement

small scale hummocky cross stratification in turbidites a form of antidune stratification small scale hummocky cross stratification occurs in upper cretaceous calciclastic turbidites exposed in the western basque pyrenees facies associations and microfossil assemblages indicate slope to base of slope bathyal depositional environments it is developed in the fine grained portion of beds and displays spacings mostly between 0 2 and 0 7 m the beds fine upward with no sharp grain size breaks or mud partings suggesting that deposition occurred during a single flow event hummocky intervals are 0 1 0 8 m thick and consistently grade laterally and vertically into flat planar laminations of bouma b divisions suggesting that deposition occurred under upper flow regime conditions they have wave like geometries with laminae continuous across crests and troughs and display a ratio of wavelength to estimated underflow thickness of 11 3 12 8 combining the above observations and inferences these examples of small scale hummocky cross stratification are interpreted as a form of antidune stratification generated by standing waves along the interface of a thinner denser underflow main body tail of the turbidity current and an overlying thicker low density layer this occurrence is further evidence that small scale hummocky cross stratification is multigenetic and therefore not indicative of a particular flow condition or depositional environment

event discrimination using regional moment tensors with teleseismic p constraints determining whether a seismic event is an earthquake explosion collapse or something more complex can be done using regional 10 s full waveform moment tensors down to low magnitudes m 3 5 the moment tensor results can be improved for sparse station configurations when teleseismic 30 array based short period t 1 s p constraints are added the inclusion of teleseismic p aids in event discrimination because it samples the lower region of the focal sphere a region where intermediate period waveforms recorded at the surface have low sensitivity for shallow event depths the teleseismic p constraint is particularly useful in reducing the trade off between a shallow explosion and a shallow volume compensated linear vector dipole with a vertical axis in compression this trade off can complicate discrimination the teleseismic p constraint is applied to the source type analysis of the announced nuclear test of the democratic people s republic of korea on 25 may 2009 resulting in greater confidence in a dominantly explosive solution

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

carbonate apron models alternatives to the submarine fan model for paleoenvironmental analysis and hydrocarbon exploration sediment gravity flow deposition along the deep water flanks of carbonate platforms typically does not produce submarine fans rather wedge shaped carbonate aprons develop parallel to the adjacent shelf slope break the major difference between submarine fans and carbonate aprons is a point source with channelized sedimentation on fans versus a line source with sheet flow sedimentation on aprons two types of carbonate aprons may develop along relatively gentle 4 platform margin slopes aprons form immediately adjacent to the shallow water platform and are referred to as carbonate slope aprons along relatively steep 4 15 platform margin slopes redeposited limestones accumulate in a base of slope setting by passing an upper slope via a multitude of small submarine canyons and are referred to as carbonate base of slope aprons both apron types are further subdivided into inner and outer facies belts inner apron sediments consist of thick mud supported conglomerates and megabreccias facies f as well as thick coarse grained turbidites facies a interbedded with subordinate amounts of fine grained peri platform ooze facies g outer apron sediments consist of thinner grain supported conglomerates and turbidites facies a as well as classical turbidites facies c with recognizable bouma divisions interbedded with approximately equal proportions of peri platform ooze facies g seaward aprons grade laterally into basinal facies of thin base cut out carbonate turbidites facies d that are subordinate to peri platform oozes facies g carbonate base of slope aprons grade shelfward into an upper slope facies of fine grained peri platform ooze facies g cut by numerous small canyons that are filled with coarse debris as well as intraformational truncation surfaces which result from submarine sliding in contrast slope aprons grade shelfward immediately into shoal water platform margin facies without an intervening by pass slope the two carbonate apron models presented here offer alternatives to the submarine fan model for paleoenvironmental analysis and hydrocarbon exploration for mass transported carbonate facies

storm deposits and storm generated coarse carbonate breccias on a pelagic outer shelf south east basin france uppermost jurassic limestones of the south east basin france are organized into four facies associations that were deposited in four distinct zones 1 peritidal lagoonal limestones 2 bioclastic and reefal limestones 3 pelagic lime mudstones 4 lime mudstones calcarenites coarse breccias calcarenite deposits of zone 4 exhibit sedimentary structures that are diagnostic of deposition under wave induced combined flow in subzone 4a both vertical and lateral transitions from lime mudstone calcarenite to breccia indicate in situ brecciation under wave cyclic loading breccias were produced by heterogeneous liquefaction of material previously deposited on the sea floor deposits in subzone 4a record relatively long periods 400 kyr of sedimentation below wave base alternating with periods of deposition under wave induced currents and periods of in situ deformation in this zone storm waves were attenuated by wave sediment interaction and wave energy was absorbed by the deformation of soft sediment with reference to present day wave attenuation water depths in this zone ranged between 50 and 80 m landwards of the attenuation zone in zone 3 storm waves were reduced to fair weather wave heights storm wave base was not horizontal and became shallower landwards as a consequence water depth and wave energy were not linearly related on a small area of the seaward edge of subzone 4a cobbles were removed by traction currents and redeposited in subzone 4b there they formed a 100 m thick wedge which prograded over 3 km and was built up by the stacking of 5 to 20 m thick cross stratified sets of coarse breccia this wedge records the transport and redeposition of cobbles by a high velocity unidirectional component of a combined flow the increase in flow velocity in a restricted area is proposed to result from flow concentration in a channel like structure of the downwelling in the gulf formed by the basin in more distal subzone 4c the hydrodynamic effect of wave induced currents was quasi permanent and brecciation by wave sediment interaction occurred only episodically this indicates that seawards of the attenuation zone hydrodynamic storm wave base was deeper than mechanical storm wave base uppermost jurassic carbonates were deposited and soft sediment deformed on a hurricane dominated ramp of very gentle slope and characterized by a zone of storm wave degeneration located seawards of a zone of sedimentation below wave base

braided and meandering submarine fan channel deposits tesnus formation marathon basin west texas abstract exposures of predominantly mid fan channel deposits from the tesnus formation upper mississippian lower pennsylvanian of west texas provide an opportunity to examine possible meandering and braided deposits in a single submarine fan system within the tesnus six fan related sedimentary facies are recognized i amalgamated sandstone without vertical thickness trends ii amalgamated sandstone with thinning upward trends iii massive matrix rich sandstone iv interbedded sandstone and shale v chaotic sandstone and shale and vi black mudrock and chert the arrangement of sedimentary facies the nature of facies contacts and sandstone geometries differ significantly for braided versus meandering channel deposits sheet like braided channel deposits commonly exhibit a more random facies ordering and abrupt facies transitions whereas pod shaped meandering channel deposits commonly possess a more orderly arrangement of facies from base to top facies i vi in sequential order with gradual facies transitions the aforementioned differences in channel deposit characteristics are believed due primarily to variations in the migrational history of the braided abandonment and rapid shifting versus meandering gradual erosion and migration channel networks

anatomy of a submarine channel system and related fan in a foramol rhodalgal carbonate sedimentary setting a case history from the miocene syn rift sardinia basin italy abstract during aquitanian burdigalian times thick mixed carbonate siliciclastic successions were deposited in basins located on the grabens and half grabens along the oligo miocene sardinia rift basin locally active tectonics sea level variations and ecological factors combined to control the development and distribution of foramol carbonate factories as well as the remobilisation and the redeposition of carbonate sediments into the adjacent deeper areas in the isili basin foramol rhodalgal carbonate factories developed on submerged structural highs which resulted from pre and syn sedimentary tectonics these carbonate factories were periodically shaved mainly during negative sea level oscillations and the sediments removed were funnelled towards the basin through a complex submarine channel network which included a tributary belt one main channel isili channel and the related fan the isili channel is up to 1 km wide 60 100 m deep and includes two stacked channel complexes each built up by several minor order channel units complex strata geometries characterise the isili channel and its related architectural elements e g overbank levee margin and channel thalweg which also include up to 15 m high bedforms individual channel complexes were temporally related to individual fan systems whose spatial distribution and internal geometry were strongly controlled by the type and rate of sediment accumulation and in turn by relative sea level oscillations facies associations include sandy to cobble sized gravity flow and bottom current deposits as well as megabreccias characterised by impressive displaced and tilted blocks which resulted from major channel margin collapses detailed analysis has led to the reconstruction of the internal geometry and depositional architecture of these carbonate bodies and to the determination of the main controlling factors the dimension and distribution of channel and channel related depositional bodies have been accurately determined this information provides a useful tool to analyse less extensively exposed analogues and to model foramol shelf to basin transitions and related channel and fan systems

crustal deformation of the lhasa terrane tibet plateau from project indepth deep seismic reflection profiles international deep profiling of tibet and the himalaya indepth deep reflection data in the yangbajain damxung graben of southern tibet yield evidence of magmatism and deformation beneath the southern lhasa terrane and yarlung zangbo suture shallow reflections and low velocity first arrivals indicate a thin quaternary graben fill of generally less than a few hundred meters thickness underlying stratified reflections extending to a maximum of about 11 5 km depth likely originate from deformed paleozoic cenozoic supracrustal strata of the lhasa terrane a prominent undulatory band of reflections within the crystalline basement extends beneath the length of the yangbajain damxung graben depth ranges from 12 km to 18 km this horizon has been interpreted to mark the top of a midcrustal partial melt zone underlying southern tibet the undulatory character of this horizon additionally suggests that it may be tectonically deformed a somewhat deeper subhorizontal wide angle reflection extends southward beneath the outcrop of the yarlung zangbo suture indicating that the suture is cut off or superposed by a younger structure at depth three gently north dipping reflections at 19 km 24 km and 27 km depth beneath the gangdese batholith are suggestive of a midcrustal duplex and may mark the northward downdip extension of the late oligocene early miocene gangdese thrust system a prominent 40 north dipping reflection imaged in the deep crust beneath the gangdese batholith between 40 and 60 km depth might mark the downdip expression of the yarlung zangbo suture or alternatively a younger reverse fault in the lower crust or both viewed in aggregate the reflection data are suggestive of moderate postcollisional shortening of the upper crust of the lhasa terrane accompanied by melting of the middle crust although the data are permissive of wholesale underthrusting or fluid injection of indian continental crust beneath the lhasa terrane they show no direct evidence for this having occurred

coarse grained submarine fan and slope apron deposits in a cretaceous back arc basin antarctica the cretaceous of west james ross island antarctica represents the proximal fill of a late mesozoic back arc basin that was probably initiated by oblique extension during the early development of the weddell sea the succession records sedimentation in two contrasting depositional systems a laterally persistent slope apron flanking the faulted basin margin interrupted both spatially and temporally by coarse grained submarine fans slope apron deposits are dominated by thinly interbedded turbiditic sandstones and mudstones mudstone association interspersed with non channelized chaotic boulder beds intraformational slump sheets and isolated exotic blocks representing a spectrum of mass flow processes from debris flow to submarine gliding localized sand rich sequences sandstone breccia association represent sandy debris lobes at the mouths of active slope chutes the submarine fan sediments conglomerate association are typified by coarse conglomerates and pebbly sandstones interpreted as the deposits of high density turbidity currents and non cohesive debris flows three assemblages are recognized and are suggested to represent components of the inner channelled zone of coarse grained submarine fans from major fan channels through ephemeral marginal channels or terraces to levee or interchannel environments the occurrence of both slope apron and submarine fan depositional systems during the early and mid cretaceous is attributed to localized input of coarse arc derived sediment along a tectonically active basin margin periods of extensive fan development were probably linked to regional tectonic uplift and rejuvenation of the arc source region cyclicity within individual fan sequences is attributed to migration or switching of fan channels or canyons slope apron sedimentation was controlled largely by intrabasinal tectonics local unconformities and packets of amalgamated slide sheets and debris flow deposits probably reflect episodic movement on basin margin faults differential subsidence across the basin margin anchored the basin slope for at least 20 myr and precluded basinward progradation of shallow marine environments

the pwaves from the amchitka island explosions summary there is evidence that the equivalent seismic sources of the amchitka island explosions longshot milrow and cannikin depart significantly from the simple model of a point compressional source in a layered elastic medium consequently modelling the observed seismograms using standard source models may not be the most efficient method of determining source properties here an alternative to modelling is used to obtain information on the seismic sources due to the explosions broad band bb estimates of the p signals are obtained from the short period sp seismograms corrected for attenuation and interpreted in terms of p pp and radiation from secondary sources the main conclusions are i bb estimates of the radiated displacement from the explosions can be obtained with only a small reduction in the signal to noise ratio seen on sp seismograms ii observations of differences in pulse amplitudes and spectra are not necessarily due to differences in anelastic attenuation iii p and pp at a given station may differ in shape so that notches in the signal spectrum may not be related to source depth iv there is evidence of arrivals that others have identified as due to slapdown but which could be interpreted as an overshoot to pp v direct interpretation of the estimated ground displacement is a better procedure for determining the seismic source properties of explosions than modelling sp seismograms using idealised models as a starting point

detailed anatomy of a deep water carbonate breccia lobe upper jurassic french subalpine basin abstract detailed correlations across tithonian carbonate breccia deposits in the drome river area northern part of the so called vocontian through suggest the depositional system was that of an elongated deep water lobe up to 70 km long and 20 to 30 km wide for a thickness reaching 200 m the drome lobe as it is now called is mainly made of slope to basinal mudstones breccias with minor platform components interpreted as debris flow and mud flow deposits associated with slump deposits it is basically a base of slope system whose elongated depositional area implies it was a point sourced gravity system thus perhaps connected to a small canyon cut onto the western slope of the basin but the mostly mudstone material of the breccias also suggests that the walls of this inferred canyon were the main supplier of the lobe not the carbonate platform proper the updip part of the lobe has a complex internal geometry as the deposition of breccia bed packages is interrupted by scourings locally 50 m deep indicating maybe a canyon mouth environment the middle part of the lobe is dominated by pure vertical aggradation of breccia beds with minor intervening erosion in the downdip part of the system a morphological compensation mechanism occurs as breccia beds tend to spread laterally a huge slump carrying large mudstone olistoliths ends the breccia deposition at the beginning of the berriasian this megaslump deposit was mostly emplaced on the right side of the breccia lobe supporting the idea of a depositional relief our observations thus show that previous interpretations as a submarine canyon infilling or as shallow water breccias formed in situ by cyclic loading under attenuating hurricane waves approaching the platform are not consistent with our observations the internal geometry of the system studied brings new data about a poorly studied kind of turbidite systems that of deep water carbonate breccias

submarine lobes and feeder channels of redeposited temperate carbonate and mixed siliciclastic carbonate platform deposits vera basin almeria southern spain temperate carbonates and mixed siliciclastics carbonates of upper tortonian age were deposited on a narrow platform along the southeastern margin of the sierra de los filabres on the western side of the vera basin the temperate carbonates were unlithified or were only weakly lithified on the seafloor and so were easily prone to synsedimentary removal part of the shelf sediments were eroded reworked and redeposited in submarine lobes up to 40 m thick and 1 km wide the lobes consist of turbiditic carbonates calcarenites and calcirudites and mixed siliciclastics carbonates which contain up to 30 siliciclasts derived from the sierra de los filabres to the northwest and abundant bioclasts of coralline algae bivalves and bryozoans in the inner platform the feeder channels of the lobes cross cut beach and shoal deposits and are filled by strings of debris flow conglomerates up to 3 m thick and a few metres wide these channels presumably developed as the continuation of river courses entering the sea further towards the outer platform they pass into large channels up to several hundred metres wide and 20 m deep steeply cutting into the horizontally bedded strata of the platform significant quantities of platform sediment were removed by erosion during their excavation once abandoned they were filled by new platform sediments further towards the basin the channels associated with the lobes exhibit lateral accretion and internal cut and fill structures and are intercalated between hemipelagic deposits the channel filling sediments are in this latter case coarse grained carbonates and mixed siliciclastics carbonates lobe development concentrated first at cortijo grande on the western side of the

generation and migration of coarse grained sediment waves in turbidity current channels and channel lobe transition zones large scale sediment waves composed of gravels and sands have been studied using deep water sidescan systems new data are presented from submarine channels off the canary islands and from canyon mouths off portugal data from other areas are briefly reviewed including a re interpretation of data from laurentian fan in order to summarise the varied morphology and setting of these bedforms coarse grained sediment waves are found in the proximal dominantly bypassing areas of deep water turbidite systems within canyons channels and channel lobe transition zones wave heights are in the region of 1 10 m and wavelengths are up to several hundred metres the distribution of waves and sparse sedimentological evidence from modern and ancient sediment wave fields suggests that initial transport and deposition of coarse sediment occurs within a high density turbidity current and not as a non newtonian debris flow in some cases the development of pronounced wave asymmetry and evidence of wave disruption and reworking suggests that the wave morphology is at least partially controlled by a later phase of low density turbidity flow grain size also appears to exert some control on wave morphology for example gravel rich waves have a greater height for the same wavelength than sand rich waves coarse grained sediment waves are often difficult to recognise on the seafloor because of reworking or burial by younger turbidity currents and are equally difficult to recognise in outcrop because of their large size

comment on q for short period p waves is it frequency dependent by a douglas summary douglas 1992 has presented evidence based on deconvolution analyses of british array data recorded from explosions at the shagan river test site sts ussr and the nevada test site nts usa from which he has concluded that the source time dependence characteristics of explosions at these test sites is significantly different from that associated with the mueller murphy m m seismic source model the objective of this note is to demonstrate that the m m model is in fact consistent with a very large variety of short period p wave observations from explosions and to argue that the alternate source time function proposed by douglas 1992 is inconsistent with both theoretical and observational constraints on the explosion source process more specifically network averaged teleseismic p wave spectra corresponding to nts french sahara and sts explosions in granite are used to illustrate the fact that the m m source model can provide remarkably good descriptions of the observed amplitude levels and spectral shapes over the short period band extending from at least 0 5 to 2 5 hz as well as seismic estimates of explosion yield which agree very closely with corresponding yield estimates obtained from other independent sources

an alternative approach to probabilistic seismic hazard analysis in the aegean region using monte carlo simulation abstract the aegean is the most seismically active and tectonically complex region in europe damaging earthquakes have occurred here throughout recorded history often resulting in considerable loss of life the monte carlo method of probabilistic seismic hazard analysis psha is used to determine the level of ground motion likely to be exceeded in a given time period multiple random simulations of seismicity are generated to calculate directly the ground motion for a given site within the seismic hazard analysis we explore the impact of different seismic source models incorporating both uniform zones and distributed seismicity a new simplified seismic source model derived from seismotectonic interpretation is presented for the aegean region this is combined into the epistemic uncertainty analysis alongside existing source models for the region and models derived by a k means cluster analysis approach seismic source models derived using the k means approach offer a degree of objectivity and reproducibility into the otherwise subjective approach of delineating seismic sources using expert judgment similar review and analysis is undertaken for the selection of peak ground acceleration pga attenuation models incorporating into the epistemic analysis greek specific models european models and a next generation attenuation model hazard maps for pga on a rock site with a 10 probability of being exceeded in 50 years are produced and different source and attenuation models are compared these indicate that greek specific attenuation models with their smaller aleatory variability terms produce lower pga hazard whilst recent european models and next generation attenuation nga model produce similar results the monte carlo method is extended further to assimilate epistemic uncertainty into the hazard calculation thus integrating across several appropriate source and pga attenuation models site condition and fault type are also integrated into the hazard mapping calculations these hazard maps are in general agreement with previous maps for the aegean recognising the highest hazard in the ionian islands gulf of corinth and hellenic arc peak ground accelerations for some sites in these regions reach as high as 500 600 cm s 2 using european nga attenuation models and 400 500 cm s 2 using greek attenuation models

seismic hazard from instrumentally recorded historical and simulated earthquakes application to the tibet himalayan region abstract we present a new approach to assessment of regional seismic hazard which accounts for observed instrumentally recorded and historic earthquakes as well as for seismic events simulated for a significantly longer period of time than that of observations we apply this approach to probabilistic seismic hazard analysis psha for the tibet himalayan region the large magnitude synthetic events which are consistent with the geophysical and geodetic data together with the observed earthquakes are employed for the monte carlo psha earthquake scenarios for hazard assessment are generated stochastically to sample the magnitude and spatial distribution of seismicity as well as the distribution of ground motion for each seismic event the peak ground acceleration values which are estimated for the return period of 475 yr show that the hazard level associated with large events in the tibet himalayan region significantly increases if the long record of simulated seismicity is considered in the psha the magnitude and the source location of the 2008 wenchuan m 7 9 earthquake are among the range of those described by the seismic source model accepted in our analysis we analyze the relationship between the ground motion data obtained in the earthquake s epicentral area and the obtained psha estimations using a deaggregation technique the proposed approach provides a better understanding of ground shaking due to possible large magnitude events and could be useful for risk assessment earthquake engineering purposes and emergency planning

comment on why earthquake hazard maps often fail and what to do about it by s stein r geller and m liu stein et al 2012 contends that the occurrence of some recent destructive earthquakes in areas mapped as low hazard in some probabilistic seismic hazard maps illustrates limitations of earthquake hazard mapping this statement is fundamentally incorrect these instances illustrate that short term observations such as recent seismicity do not characterize the hazard from faults with long recurrence time earthquakes this is not an inherent limitation in the methodology of probabilistic seismic hazard assessment psha they repeat arguments made in their previous articles one of them recent stein et al 2011 and others on the new madrid region of the central united states that were published and commented on several years ago e g frankel 2003 2004 stein et al 2003 stein et al 2012 makes three major points 1 the inputs to seismic hazard maps should include long term geologic data in addition to historical and instrumental seismicity 2 uncertainties in hazard values should be estimated and communicated to users and 3 seismic hazard maps need to be objectively tested the first two points have long been recognized and practiced in the seismic hazard mapping community in the united states and elsewhere the third point has also been the subject of substantial work e g stirling and petersen 2006 this comment points out problems

the base of slope carbonate breccia system of ceuse tithonian s e france occurrence of progradational stratification in the head plug of coarse granular flow deposits abstract once interpreted as a deep water canyon infilling and later as some kind of tempestite deposit the tithonian breccias of ceuse are here reinterpreted as a small lobe deposit emplaced at the mouth of a gully cutting into a slope between two deep water terraces in the eastern part of the subalpine basin the breccias belong to two basic categories mostly grain supported and occasionally mud supported spectacular large scale oblique geometries apparent lateral accretions are observed in the grain supported breccias both within the infilling of the lower feeder channel and in the updip part of the lobe detailed analyses of these geometries show that they correspond to progradational features both laterally and in a more distal position on the lobe these progradational bodies evolve into a pile of unsorted massive breccias sometimes showing a crude even stratification we thus propose a depositional model for the grain supported breccias linking the two facies as follows the deposition of a gravity flow begins at the toe of slope mouth of the tributary gully by a progradational head which evolves downslope and laterally to a splay of massive or crudely stratified breccia the internal oblique stratification flattens distally over a distance of a few kilometres elementary beds pile up in morphological compensation to build the 100 m thick breccia body of ceuse because the breccias are derived from the gravity reworking of deep water nodular carbonates there is no sand sized material available in the depositional system or only a little probably produced through an erosive clast grain diminution process during transport this explains why the thick breccia beds pass quickly eastward to thin bedded mud turbidites

recognition of earthquake related damage in archaeological sites examples from the dead sea fault zone abstract archaeological structures that exhibit seismogenic damage expand our knowledge of temporal and spatial distribution of earthquakes afford independent examination of historical accounts provide information on local earthquake intensities and enable the delineation of macroseismic zones they also illustrate what might happen in future earthquakes in order to recover this information we should be able to distinguish earthquake damage from anthropogenic damage and from other natural processes of wear and tear the present paper reviews several types of damage that can be attributed with high certainty to earthquakes and discusses associated caveats in the rare cases where faults intersect with archaeological sites offset structures enable precise determination of sense and size of slip and constrain its time among the characteristic off fault damage types i consider horizontal shifting of large building blocks downward sliding of one or several blocks from masonry arches collapse of heavy stably built walls chipping of corners of building blocks and aligned falling of walls and columns other damage features are less conclusive and require additional evidence e g fractures that cut across several structures leaning walls and columns warps and bulges in walls circumstantial evidence for catastrophic earthquake related destruction includes contemporaneous damage in many sites in the same area absence of weapons or other anthropogenic damage stratigraphic data on collapse of walls and ceilings onto floors and other living horizons and burial of valuable artifacts as well as associated geological palaeoseismic phenomena such as liquefaction land and rock slides and fault ruptures additional support may be found in reliable historical accounts special care must be taken in order to avoid circular reasoning by maintaining the independence of data acquisition methods

geometry and petrophysical parameters of a calcarenitic turbidite lobe barremian aptian pas de la cluse france abstract several bioclastic resedimentation systems late barremian to early aptian in age outcrop in southeastern france the upslope portion of a calcarenitic turbidite lobe outcrops as a cliff 2 3 km wide and up to 45 m high oriented roughly perpendicular to the direction of palaeoflow it has been studied through 31 sections the studied body is point sourced and corresponds to a channel lobe transition located at the toe of slope of a urgonian carbonate platform on the western edge of the vocontian trough french subalpine chains the internal geometry of the lobe is the result of repeated erosion and filling of channels creating well defined stacked units filling phases result in lobe shaped morphology units evolve from base to top in an ordered way first the sediments exported from the platform and deposited in the basin are represented by decimetre thick sheet like and fine grained bouma a e and ab e sequences in this first unit erosion is limited and represented by shallow and symmetrical channels this initial phase of deposition corresponds to the formation of a lobe with a positive morphology the next phase of system development is more erosional and this is dominated by migrating sinuous channels several metres deep filled with coarse grained poorly graded turbidites these channels are first filled through lateral accretion and then sediment spills over to create a sub lobe the mixture of channel and lobe features could be considered as a carbonate equivalent of the channel levee system of siliciclastic deposits finally the system ends with the deposition of a flat based unit this unit extends for more than 2 km and is composed of the southwards lateral accretion of hundreds of metres wide sequences each composed of a debris flow deposit capped by a coarse grained calcarenite bed these sigmoidal bodies could be the ultimate forms of a spreading out phenomenon of the lobe overall the pas de la cluse system is a coarsening upward body as the grain size is related to the nature of the material this coarsening upward implies either an evolution in the nature of the carbonate material produced on the platform from grainy to bioconstructed a displacement of the source sediment from inner platform to margin or a displacement of the channel head through time from distal to proximal the upward evolution from classic turbidites to debris flow deposits can be explained either by the way the platform facies evolved with time in a depositional sequence or through retrogressive erosion by successive slope failures that cut deeper and deeper into the platform slope although its present day porosity is low the size of the system and the fact that it is encased in marls make it an interesting outcrop analogue for hydrocarbon exploration

progradational patterns at the head of single units of base of slope submarine granular flow deposits conglomerats des gâs coniacian se france upper cretaceous conglomerates sandstones and calcarenites outcropping in the glandage syncline les gas gorge belong to two superimposed turbidite systems the first being the shortest about two hundred metres thick five kilometres wide and a mere ten kilometres long both onlap a sw ne oriented palaeoslope created by faulting in the latest turonian on the southern edge of the vercors carbonate platform the first system is coniacian in age the second probably campanian this study deals only with the first system which comprises in stratigraphic order classical sandstone turbidites clast supported conglomerates and coarse grained cross bedded sandy calcarenites the transition between the last two lithologies is progressive allowing the mechanisms responsible for apparent lateral accretions found pervasively in both the conglomerates and the calcarenites to be understood here cross bedding is not the result of changes in the direction of accretion in lateral bars or in oblique infillings of sinuous channels as is often suggested in other similar deep water carbonate systems each event bed comprises a prograding conglomeratic head plug blanketed in continuous sedimentation by forward spreading bioclastic calcarenites the superimposition of such mixed beds gives rise to a low angle cross stratification an unusual feature for a system interpreted as a base of slope apron conglomerates were probably deposited through a granular flow mechanism at a strong hydraulic jump at the base of the slope associated calcarenites show supercritical flow features the undulating transverse architecture of its large head onlapping the paleoslope suggests it is a multi apex apron the sandstone conglomerate calcarenite succession of the depositional sequence is interpreted as overall transgressive after the late turonian tectonic phase that led to the exposure of the vercors carbonate platform updip

hummocky cross stratification like structures in deep sea turbidites upper cretaceous basque basins western pyrenees france hummocky cross stratification is a sedimentary structure which is widely interpreted as the sedimentary record of an oscillatory current generated by energetic storm waves remobilizing surface sediment on the continental shelf sedimentary structures named hummocky cross stratification like structures similar to true hummocky cross stratification have been observed in the turonian senonian basque flysch basin south west france the bathymetry 1000 to 1500 m suggests that the observed sedimentary structures do not result from a hydrodynamic process similar to those acting on a continental shelf the morphology of these three dimensional structures shares similarities with the morphology of hummocky cross stratification despite a smaller size the lateral extent of these structures ranges from a few decimetres to many decimetres they consist of convex up domes hummock and concave up swales with a non erosive base four types of hummocky cross stratification like geometries are described they occur in association with structures such as climbing current ripple lamination and synsedimentary deformations in the basque flysch hummocky cross stratification like structures are only found in the tc interval of the bouma sequence hummocky cross stratification like structures are sporadic in the stratigraphic series and observed only in few turbidite beds or bed packages this observation suggests that hummocky cross stratification like structures are linked genetically to the turbidity current but form under a very restricted range of parameters these structures sometimes show an up current upslope migration trend antidunes in the described examples they could result from standing waves forming at the upper flow interface because of kelvin helmholtz instability

reply to comment by j r murphy on q for short period p waves is it frequency dependent by a douglas using network averaged spectra murphy 1989 demonstrates that if it is assumed that the source functions of explosions at pahute mesa nevada test site nts are as predicted by the mueller murphy m m source model then the average t at around 1 hz for p waves radiated from the test site must be about 0 75 s with this value of t murphy 1989 estimates the best fitting m m spectrum for each explosion studied by adjusting a to c a to being the amplitude and delay time of pp relative to p and c the wave speed for the material in which the explosion was fired the absolute amplitudes of the theoretical spectra are obtained using a calibration factor estimated from the data murphy 1993 extends the analysis to explosions in granite at the nevada french sahara and e kazakh test sites for the french sahara explosion t is assumed to be 0 75 s murphy s estimate for nts explosions and for the e kazakh explosion a t of 0 55 s is used for the french sahara and e kazakh explosions murphy 1993 shows that by using the same calibration factor as for the nts it is possible by varying a to to fit the estimated average network spectra using the m m granite source murphy 1993 states that the amplitudes and spectra for the largest nts explosion in granite pile driver can also be predicted using the m m model but these results are not shown

societal and observational problems in earthquake risk assessments and their delivery to those most at risk abstract losses from earthquakes continue to rise despite increasingly sophisticated methods to estimate seismic risk throughout the world this article discusses five specific reasons why this should be loss of life is most pronounced in the developing nations where three factors poverty corruption and ignorance conspire to reduce the effective application of seismic resistant codes a fourth reason is that in many developing nations the application of seismic resistant construction is inadvertently restricted to wealthy or civil segments of the community and is either unobtainable or irrelevant to the most vulnerable segment of the public the owner occupiers of substandard dwellings a fifth flaw in current seismic hazard studies is that sophisticated methodologies to evaluate risk are inappropriate in regions where strain rates are low and where historical data are short compared to the return time of damaging earthquakes the scientific community has remained largely unaware of the importance of these impediments to the development and application of appropriate seismic resistant code and is ill equipped to address them