surface waves tomography and non linear inversion in the southeast carpathians abstract a set of shear wave velocity models of the lithosphere asthenosphere system in the southeast carpathians is determined by the non linear inversion of surface wave group velocity data obtained from a tomographic analysis the local dispersion curves are assembled for the period range 7 150 s combining regional group velocity measurements and published global rayleigh wave dispersion data the resolution of the tomography data is improved using a priori information about the shallow crustal velocity structure the lithosphere asthenosphere velocity structure is reliably reconstructed to depths of about 250 km for 27 cells with size 1 1 the adopted non linear inversion method computes a set of acceptable velocity models for each cell local smoothness optimization lso is applied to select the representative cellular structures and the three dimensional shear wave velocity model of the studied region is assembled interpretation of the obtained structure shows that the thickness of the lithosphere in the region varies from about 90 km to 170 km and the asthenosphere can be as deep as about 150 km mantle seismicity concentrates where the high velocity lid is detected just below the moho the obtained results are in agreement with recent seismic refraction receiver function and travel time p wave tomography investigations in the region the similarity among the results obtained from different kinds of structural investigations including the present work highlights some new features of the lithosphere asthenosphere system in southeast carpathians such as the relatively thin crust under transylvania basin and in the vrancea zone

scaling law and its applications to earthquake statistical relations abstract the spectra of the far field body wave displacement for earthquakes of various magnitudes have been obtained using a two dimensional faulting model on a rectangular fault there are three corner frequencies f c 1 f c 2 and f c 3 in the displacement spectra f c 1 and f c 2 relate to faulting times for the long and wide directions on the rectangular fault respectively and f c 3 corresponds to the rise time of the source time function according to these three corner frequency values four spectral regions are defined u u 0 f 0 f f c 1 in the first region u 1 f f c 1 f f c 2 in the second region u 1 f 2 f c 2 f f c 3 in the third region and u 1 f 3 f f c 3 in the fourth region this results in different source parameter relations for different magnitude ranges i e different seismic moment ranges because the attenuation rates depend on frequency it is supposed that earthquake faulting is satisfied by three conditions of geometrical similarity stress environment and dynamic similarity therefore seismic moment faulting time along the length and width of the fault and rise time can all be scaled with fault length the constants in the scaling relations can be determined from seismic moment data for about 800 earthquakes that occurred during 1981 1983 and are given by dziewonski and woodhouse 1983 and m s and m b data from the isc bulletin thus the source parameter relations between m s and m b m s and m l m b and m l log m o and log s fault area log s and m s log l fault length and m s and log d average dislocation and m s can be deduced from the scaling law rather than from pure statistical relations these relations are statistically consistent with the observed data the average rupture velocity of the fault can also be estimated from the scaling law it is 2 65 km s the total time of rupture is 0 35 s km l km which is close to that estimated by kanamori 1981 and the dislocation slip rate is 287 1143 cm s

identifying the behavioural characteristics of clay cliffs using intensive monitoring and geotechnical numerical modelling abstract coastal monitoring is routinely undertaken to provide an archival record of cliff line movement that can be used in the development and validation of predictive coast retreat and evolution models however coastal monitoring is often purely quantitative in nature and financial necessity requires deployment over extensive coastal sections as a result for local site conditions in particular only limited geomorphological data are available or included during the development of such predictive models this has resulted in many current models incorporating a simplistic or generalised representation of cliff behaviour an approach that progressively loses local credibility when deployed over extensive heterogeneous coastlines this study addresses this situation at a site of extreme coastline retreat holderness uk through the application of intensive monitoring of six representative cliff sections nested within a general geomorphological appraisal of the wider coastline as a whole the data from these surveys have been used to validate a finite difference based geotechnical modelling assessment of clay cliff stability once validated the geotechnical model was used to simulate a range of scenarios that were sufficient to represent the range of topographic hydrogeological geological and littoral conditions exhibited throughout the region our assessment identified that the cliff retreat occurs through the combined influence of direct marine erosion of the cliff with shallow structurally controlled failures or substantial mass failures critically the predisposition to any one of these failure mechanisms arises principally as a result of initial cliff height the results of the numerical modelling have been combined into an empirical slope model that derives the rate of landslide induced retreat that would arise from mass failures under various future scenarios results of this study can be used in the selection and development of retreat models at coastlines of similar physiographic setting to that found at holderness the results represent a key step in linking material deformation properties to the processes of cliff change and the subsequent range of landforms found on clay cliffs as such the results could also be used more generally to illustrate the likely cliff behaviour of other soft rock coastlines

intermittent surging movements of a coastal landslide since the late 1960s there has been a large mudslide in coastal cliffs of permo triassic strata conglomerate overlying mudstone at west down beacon 2 km west of budleigh salterton devon a total displacement of 100 m was achieved between 1981 and 1985 as the lobate toe of the mudslide pushed forward across the beach in eleven surges of movement each surge involved a displacement of between 5 and 15 m and was completed within a few hours the toe moved by planar sliding possibly on more than one seaward dipping shear surface or zone occasionally there were additional relatively minor displacements less than 1 m but normally the mudslide was stationary between the major surges after each surge high oblique aerial photographs were obtained for stereoscopic interpretation debris falls from the cliff appear to have triggered some of the mudslide surges a displacement recording of one surge has indicated that the rate of movement of the mudslide may have been partly controlled by variations in sea level during the tidal cycle

high resolution sequence stratigraphy of clastic shelves iii applications to reservoir geology abstract high frequency clastic shelf sequences contain porous deposits consisting of coastal to shallow water sandstones and conglomerates which may represent very good reservoirs and therefore critical targets for exploration and production as well as for fluid hydrocarbon water or co2 storage the study of these reservoirs following a sequence stratigraphic approach is essential to predict their features and distribution within systems tracts forming high frequency sequences which in turn compose higher rank systems tracts and sequences a critical aspect to improve the exploitability of the reservoirs is their heterogeneity which directly affects the volume of the reservoirs and determine internal compartmentalization the heterogeneity can be primary related to depositional processes influencing grain size and facies distribution and secondary related to diagenesis in particular the primary heterogeneity is referred to the facies variability from distal to proximal settings to the accumulation of condensed shell beds and to facies characteristics of bedsets whereas the secondary heterogeneity derives from diagenetic processes at sequence stratigraphic surfaces and facies contacts and within sandbodies both the distribution of reservoirs and their heterogeneity can be predicted following a high resolution sequence stratigraphic approach ultimately the integration of subsurface data with the analysis of outcrop analogs is essential to better understand the features of clastic shelf reservoirs and to develop 3d models of fluid migration

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

quantitative modeling of the lithosphere dynamics earthquakes and seismic hazard abstract understanding of lithosphere dynamics tectonic stress localization earthquake occurrences and seismic hazards has significantly advanced during the last decades meanwhile despite the major advancements in geophysical sciences yet we do not see a decline in earthquake disaster impacts and losses although earthquake disasters are mainly associated with significant vulnerability of society comprehensive seismic hazards assessments and earthquake forecasting could contribute to preventive measures aimed to reduce impacts of earthquakes modeling of lithosphere dynamics and earthquake simulations coupled with a seismic hazard analysis can provide a better assessment of potential ground shaking due to earthquakes here we present a block and fault dynamics bafd model which simulates earthquakes due to lithosphere dynamics and allows for studying the influence of fault network properties and regional movements on seismic patterns the model s performance is analyzed in terms of reproduction of basic features of the observed seismicity such as the frequency magnitude relationship clustering of earthquakes occurrences of large events fault slip rates and earthquake mechanisms several studies related to the application of the bafd model to the following earthquake prone regions are reviewed the southeastern carpathians caucasus the western india tibet himalaya and the sunda arc we examine then a new approach to seismic hazard analysis which is based on instrumentally recorded historical and bafd simulated earthquakes and analyze how earthquake modeling can assist in hazard assessment finally we discuss perspectives in modeling of earthquake occurrences and improvements in hazard assessment

haynesville and bossier mudrocks a facies and sequence stratigraphic investigation east texas and louisiana usa abstract upper jurassic haynesville and bossier shale gas plays of the northwestern gulf of mexico gom basin produce from organic rich marine transgressive to highstand mudrocks within mixed carbonate clastic depositional systems modern wireline log suites from 200 deep wells were used for detailed correlations and 10 cores throughout the upper kimmeridgian to lower tithonian basin were incorporated into detailed facies stratigraphic and lithologic analyses the haynesville shale lies within a 2nd order transgressive systems tract tst that encompasses back stepping ramp carbonates proximal and marine shales distal below a maximum flooding surface mfs this shale onlaps retrogradational carbonates and basement highs and is capped by the 2nd order mfs bossier shales and local sandstones prograde basinward above the haynesville shale and downlap the 2nd order mfs they grade upward and updip into the thick highstand systems tract hst fluvio deltaic sandstones of the cotton valley group distally organic rich facies developed in restricted bossier environments creating another productive gas shale opportunity several preexisting basement highs in the south and carbonate platforms in the northwest and west restrict and partition the basin thus influencing deposition of highly organic versus nonorganic and siliciclastic dominated versus carbonate dominated lithologies haynesville and bossier shales each compose three upward coarsening cycles that probably represent 3rd order sequences within the larger 2nd order tst and early hst respectively most of the three bossier 3rd order cycles are dominated by varying amounts of siliciclastics deposition of the haynesville mudrocks occurred below storm wave base under mostly dysoxic conditionsm allowing settlement of benthic bivalve communities and bioturbating organisms and oscillating periodically to more anoxic conditions on the seafloor however most of the sparse faunae found in these mudrocks are of planktonic origin bossier mudrocks exhibited more oxygenated and clastic rich lithologies related to progradation of the clastic shoreline and sea level highstand knowledge of lithologic stratigraphic geochemical and faunal variations across mudrock basins needs to be detailed so that shale gas basins might be successfully explored

integrated transnational macroseismic data set for the strongest earthquakes of vrancea romania abstract a unique macroseismic data set for the strongest earthquakes occurring since 1940 in the vrancea region is constructed by a thorough review of all available sources inconsistencies and errors in the reported data and in their use are also analysed the final data set which is free from inconsistencies including those at the political borders contains 9822 observations for the strong intermediate depth earthquakes 1940 mw 7 7 1977 mw 7 4 1986 mw 7 1 1990 may 30 mw 6 9 1990 may 31 mw 6 4 and 2004 mw 6 0 this data set is available electronically as supplementary data to the present paper from the discrete macroseismic data the continuous macroseismic field is generated using the methodology developed by molchan et al 2002 the procedure along with the unconventional smoothing method modified polynomial filtering mpf uses the diffuse boundary db method which visualises the uncertainty in the isoseismal boundaries the comparison of dbs with previous isoseismal maps supplies a good evaluation criterion of the reliability of earlier published maps the produced isoseismals can be used not only for the formal comparison of the observed and theoretical isoseismals but also for the retrieval of source properties and the assessment of local responses molchan et al 2011

tertiary subduction and slab break off model of the carpathian pannonian region abstract this paper illustrates the application of multidisciplinary data analysis to the carpathian pannonian region and presents a new tertiary development model that incorporates all multidisciplinary parameters during the late cretaceous eocene the future carpathian orogen was part of the larger alpine carpathian orogen formed by the southeastward subduction 135 55 ma of the penninic ocean and the ultimate collision 55 40 ma of the european and adriatic continents the subduction in the alpine region ended by the slab break off of the subducting oceanic lithosphere from the continental one and by the related magmatism 43 24 ma while the eocene alps were under continental collision the eocene remnant carpathian flysch basin rcfb was still subducting the carpathians and eastern parts of the alps started to occupy the region of the present carpathians during the early miocene the oceanic plate underlying the rcfb subducted southwestwards later westwards while the northeastward and eastward migration velocity of the accreting plate boundary decreased through time the slower subduction rate caused a steeper dip of the subducting slab the beginning of the eggenburgian 22 19 ma and following duration of extension in the orogenic hinterland accompanied by the asthenosphere upwelling the onset of the crustally derived volcanism above the risen asthenosphere and the younger mantle derived volcanism progressively less contaminated by the crustal material all contemporaneous with a shortening in the carpathian accretionary wedge the subduction of the rcfb finally led at the end of the early miocene to a collision with the continental margin along the westernmost part of the present carpathian arc the subduction roll back of the subducting slab of the rcfb under the advancing inner carpathians the oblique closure of the basin the progressive change of the subduction to collision from the west to the east along the carpathian arc drove a scissors like break off of the subducting oceanic slab along the west carpathians the break off in the east carpathians was driven by the weight of a subducting oceanic slab and buoyancy of the attached continental slab the break off started in the west of the carpathian arc in the early miocene ran along the arc to its present position in the bend area between the east and south carpathians and separated the oceanic slab that subducted passively under its own weight from the european continental margin the lateral propagation rate of the slab tear decreased with time the break off related volcanism was synchronous with the final stages of the collision

sedimentary geochemistry of manganese implications for the environment of formation of manganiferous black shales the sedimentary geochemistry of manganese is dominated by the redox control of its speciation higher oxidation states mn super 3 and super 4 occurring as insoluble oxyhydroxides in well oxygenated environments and the lower oxidation state mn super 2 being much more soluble in oxygen deficient settings its geochemical behavior is therefore quite different in oxic and anoxic environments and where oxic and anoxic conditions are juxtaposed mn is recycled between the two environments in modern marine sediments mn is present above its crustal abundance as an oxyhydroxide in all slowly accumulating pelagic sediments of the deep ocean and in surficial deposits of continental margin environments diagenetic recycling of mn in the latter causes surficial deposits to have larger mn enrichments than in many pelagic sediments bottom sediments of permanently anoxic basins show no enrichments and have mn concentrations that are controlled solely by the aluminosilicate fraction manganese carbonates kutnohorite and calcic rhodochrosite are found only in anoxic sediments accumulating beneath surface oxic horizons and therefore under oxygenated bottom waters in many nearshore environments such enrichments are due to delivery of mn by burial of surface oxyhydroxides into the subsurface anoxic environment where they are dissolved pore water mn levels can reach saturation with respect to a mixed mn ca carbonate phase in such sediments the diagenetic origin for these phases is shown by their carbon isotope compositions which typically indicate a carbon source from decomposing organic matter the presence of mn carbonates therefore signifies that the host sediment must have accumulated under oxygenated bottom waters on the basis of this information it is proposed that in contrast to several current explanations for the formation of mn carbonates kutnohorite and rhodochrosite in ancient organic rich shales limestone and marl sequences and in many mn ore deposits the occurrence of these mineral phases indicates that the sediments originally accumulated beneath oxygenated bottom waters by analogy with the present mn carbonates could not have formed in the bottom waters of anoxic basins these diagenetic phases however did form where mn was supplied at a high rate namely by the burial of oxyhydroxide enriched surface sediments to a subsurface anoxic environment this situation could only have occurred under oxygenated bottom waters the presence of mn carbonates in ancient black shales and in some carbonate rich rocks lends strong support to the notion that these rocks did not necessarily form in anoxic basins but owe their carbon richness to a high supply of organic matter to sediments deposited under oxygenated bottom waters probably in continental margin settings

a pattern in the incidence of major coastal mudslides the communication considers eroding coastal cliffs which consist predominantly of stiff fissured clay overlying a more resistant stratum the contact having a gentle component of coastwise dip from the southern coasts of england five such cliffs are described in each of these a zone of dominant mudsliding exists which stands out from the background of lesser mudslides and other forms of failure the common feature is that in each case the zone of major mudsliding coincides closely with the length of cliff over which the base of the clay stratum lies within the tidal range and generally within the upper part of this it is suggested that this pattern results from optimum conditions for continuing stimulation of mudslide activity by toe erosion being reached in the above zone

vrancea99 the crustal structure beneath the southeastern carpathians and the moesian platform from a seismic refraction profile in romania the vrancea99 seismic refraction experiment is part of an international and multidisciplinary project to study the intermediate depth earthquakes of the eastern carpathians in romania as part of the seismic experiment a 300 km long refraction profile was recorded between the cities of bacau and bucharest traversing the vrancea epicentral region in nne ssw direction the results deduced using forward and inverse ray trace modelling indicate a multi layered crust the sedimentary succession comprises two to four seismic layers of variable thickness and with velocities ranging from 2 0 to 5 8 km s the seismic basement coincides with a velocity step up to 5 9 km s velocities in the upper crystalline crust are 5 9 6 2 km s an intra crustal discontinuity at 18 31 km divides the crust into an upper and a lower layer velocities within the lower crust are 6 7 7 0 km s strong wide angle pmp reflections indicate the existence of a first order moho at a depth of 30 km near the southern end of the line and 41 km near the centre constraints on upper mantle seismic velocities 7 9 km s are provided by pn arrival times from two shot points only within the upper mantle a low velocity zone is interpreted travel times of a plp reflection define the bottom of this low velocity layer at a depth of 55 km the velocity beneath this interface must be at least 8 5 km s geologic interpretation of the seismic data suggests that the neogene tectonic convergence of the eastern carpathians resulted in thin skinned shortening of the sedimentary cover and in thick skinned shortening in the crystalline crust on the autochthonous cover of the moesian platform several blocks can be recognised which are characterised by different lithological compositions this could indicate a pre structuring of the platform at mesozoic and or palaeozoic times with a probable active involvement of the intramoesian and the capidava ovidiu faults especially the intramoesian fault is clearly recognisable on the refraction line no clear indications of the important trotus fault in the north of the profile could be found in the central part of the seismic line a thinned lower crust and the low velocity zone in the uppermost mantle point to the possibility of crustal delamination and partial melting in the upper mantle

coastal hazard assessment and mapping in northern campania italy abstract in the northern campanian coastal zone over 150 km long three geomorphic units are recognised 1 sandy beaches that are well developed in the northern area where a prominent river mouth volturno river is also present 2 steep and rocky shores often with gravelly beaches or debris cones at their base are mainly diffuse in the southern area sorrentine peninsula and lastly 3 techno coast shorelines stabilized with revetments and seawalls as well as former natural environments no longer clearly operational because of urbanization as is visible in naples and in the vesuvian coast six primary hazards are considered in this investigation shoreline erosion riverine flooding storms landslides seismicity and volcanism and man made structures these hazards do not have a uniform distribution along this coast in terms of their frequency and intensity moreover both their interaction and the intensive action of humans often uncontrolled makes it difficult to assess the overall coastal hazard in this paper a semi quantitative method with which to quantify rank and map the distribution of hazard is applied along this particular stretch of coast in such a stretch previously characterized in terms of types and processes and compartmentalized into geomorphic units the effect of individual hazards based on their magnitude and recurrence is evaluated dominant and subordinate hazards for each geomorphic unit are identified assigning a rank that is also a weighting comparison of each weighting through an interaction matrix permits the calculation of a resultant which is the overall hazard assessment and which can be expressed cartographically the results obtained for a coastal zone with one of the highest pressures from urbanization in the world help us to recognise that this approach could become a useful tool to aid decision making regarding coastal land use and planning

a multiproxy lake record from inner mongolia displays a late holocene teleconnection between central asian and north atlantic climates in order to study how the holocene central asian climate is coupled to the global climate system a 4 24 m long lake core from western inner mongolia in china was studied using a multiproxy approach sedimentology and geochemical parameters such as gypsum and dolomite content presence of lakeshore sand changing to aeolian sand and changes in paleomagnetic properties bear witness to a trend toward a generally drier climate over the late holocene aridification is linked to the southward retreat of the northern boundary of the asian summer monsoon leaving central asia under the influence of the westerly belt the weakening of the asian summer monsoon in turn was caused by an orbitally driven decrease in summer insolation the weakening summer insolation also likely increased the intensity of the siberian high pressure system further promoting aridification of central asia on a shorter time scale the multiproxy record shows the climate to have been relatively dry during the medieval warm period ad 800 1100 with the ensuing humid environment at the end of this period gradually turning to become extremely dry ad 1100 1550 at the little ice age maximum switches in the north atlantic oscillation caused these changes through a teleconnection in the form of westerlies these westerlies provided most of central asia s moisture after the retreat of the asian summer monsoon the central asian climate therefore corresponds closely with late holocene european climate changes

geological and geochemical characterization of the lower cretaceous pearsall formation maverick basin south texas a future shale gas resource as part of an assessment of undiscovered hydrocarbon resources in the northern gulf of mexico onshore mesozoic section the u s geological survey usgs evaluated the lower cretaceous pearsall formation of the maverick basin south texas as a potential shale gas resource wireline logs were used to determine the stratigraphic distribution of the pearsall formation and to select available core and cuttings samples for analytical investigation samples used for this study spanned updip to downdip environments in the maverick basin including several from the current shale gas producing area of the pearsall formation the term shale does not adequately describe any of the pearsall samples evaluated for this study which included argillaceous lime wackestones from more proximal marine depositional environments in maverick county and argillaceous lime mudstones from the distal lower cretaceous shelf edge in western bee county most facies in the pearsall formation were deposited in oxygenated environments as evidenced by the presence of biota preserved as shell fragments and the near absence of sediment laminae which is probably caused by bioturbation organic material is poorly preserved and primarily consists of type iii kerogen terrestrial and type iv kerogen inert solid bitumen with a minor contribution from type ii kerogen marine based on petrographic analysis and pyrolysis carbonate dominates the mineralogy followed by clays and quartz the low abundance and broad size distribution of pyrite are consistent with the presence of oxic conditions during sediment deposition the pearsall formation is in the dry gas window of hydrocarbon generation mean random vitrinite reflectance values ro 1 2 2 2 and contains moderate levels of total organic carbon average 0 86 wt which primarily resides in the inert solid bitumen solid bitumen is interpreted to result from in situ thermal cracking of liquid hydrocarbon generated from original type ii kerogen that was prevented from expulsion and migration by low permeability the temperature of maximum pyrolysis output tmax is a poor predictor of thermal maturity because the pyrolysis s2 peaks from rock eval analysis are ill defined vitrinite reflectance values are consistent with the dry gas window and are the preferred thermal maturity parameter a maverick basin pearsall shale gas assessment unit was defined using political and geologic boundaries to denote its spatial extent and was evaluated following established usgs hydrocarbon assessment methodology the assessment estimated a mean undiscovered technically recoverable natural gas resource of 8 8 tcf of gas and 3 4 and 17 8 tcf of gas at the f95 and f5 fractile confidence levels respectively significant engineering challenges will likely need to be met in determining the correct stimulation and completion combination for the successful future development of undiscovered natural gas resources in the pearsall formation

high resolution teleseismic body wave tomography beneath se romania i implications for three dimensional versus one dimensional crustal correction strategies with a new crustal velocity model summary the calixto carpathian arc lithosphere x tomography experiment offers a dense high quality data set to study the lithospheric asthenospheric system underneath se romania an earthquake prone region in se europe to increase the image resolution of structures in the uppermost mantle the application of crustal traveltime corrections by a priori information before the teleseismic traveltime inversion has become a well accepted procedure for such a correction we present a regional 3 d crustal seismic velocity model that serves as the basis for a high resolution teleseismic tomography forthcoming paper by martin et al our 3 d crustal model is based on recent research in the region we collect new results from two long range seismic refraction lines 3 d refraction tomography and teleseismic ps conversions adding previously published models of the sediment distribution conrad and moho depths as well as crustal seismic p wave velocities we compile a 3 d crustal model for se romania this 3 d model does not contain shallow small scale heterogeneities 10 km but it reflects the large scale structures such as variations in sediment thickness average seismic velocities and 3 d moho depth it is well suited for the correction of teleseismic traveltime residuals a prerequisite for a high resolution teleseismic tomography study for example traveltime delays of up to 1 3 s are caused by the almost 20 km thick layer of sediments in the focsani basin such delays are comparable to or larger in size than the expected upper mantle traveltime residuals we study the significance of 3 d crustal traveltime corrections relative to 1 d station corrections and show that the complex basin structures in se romania require a 3 d approach to reduce the smearing of crustal anomalies into the mantle by modelling synthetic mantle structures with a slab as it is expected for se romania we also investigate how to adapt the inversion strategy if crustal corrections are applied significant improvements are found by including the already corrected crustal layers in the inversion procedure thereby enabling the inversion algorithm to project still remaining uncertainties in the less resolved upper crustal layers however the fixing of the upper layers during the inversion due to the a priori knowledge of the crustal velocity anomalies clearly leads to smearing of uncorrected anomalies that are possibly located close to the crust mantle boundary

tectonothermal processes and mechanical strength in a recent orogenic belt northern apennines 1 this paper investigates the seismic cutoff temperature at the maximum depth of seismicity across a young orogenic belt the northern apennines by attempting to take account of the different tectonothermal processes which have occurred in the region since the last 20 myr the analysis of seismicity over a period of 20 years 1981 2002 in combination with the thermal regime shows that the western part of the northern apennines peri tyrrhenian zone is characterized by extensional tectonics few earthquakes generally shallow and of low magnitude and high surface heat flux the entire crust of the eastern part of the orogenic belt external zone is affected by seismic activity of moderate magnitude and low heat flux earthquakes increase both in number and energy released in the inner portion of the belt internal zone where events with larger focal depth indicate subduction the cutoff potential temperature at the largest depth of seismicity is 550 c for the internal zone in the external zone of the orogen the temperature at the maximum depth of seismicity is about 550 c this result agrees with recent work on the thermal structure and seismicity of several continental areas the limiting temperature in the peri tyrrhenian zone can instead exceed 750 c a possible explanation is that the deepest earthquakes might be associated to magma movement the overall earthquake spatial distribution across the orogen appears related to the long term rheology which varies roughly in the same direction of tectonic transport of the chain this consistency appears also from the b value of the frequency magnitude relation which can be interpreted in relation to the rheological properties of the medium the b value seems to be inversely correlated to the expected mechanical strength of the crust and increases eastward in the direction of tectonic transport the largest number of shocks and magnitude of the internal zone happen where a sharp lateral change of strength should occur

characteristics of romanian lithosphere from deep seismic reflection profiling abstract the tectonic units of romania contain both alpine orogenic regions and platforms the investigations of crustal structure by near vertical reflection seismic profiling are based on less than 100 lines unequally distributed and of limited lengths 5 30 km the seismic features studied are the crustal seismic reflectivity and transparency dipping events and diffractions and the moho and subcrustal reflectivity the major common features are a reflective sedimentary cover of mostly neogene layers a weak signal from the sedimentary basement boundary a quasi transparent upper crust a mid crust with short and subhorizontal events a transparent or layered lower crust and a moho that is either poorly visible or evidenced by a zone with reflection bands and some subcrustal reflections the moesian platform together with the adjacent carpathian foredeep show a mid crust with short and subhorizontal events a crust mantle transition zone in the west an unclear or prominent moho and some subcrustal reflectivity the northern part of the carpathian foredeep shows strong seismic layering of the lower crust the central part of the transylvanian depression is characterized by short and subhorizontal events at mid crustal level a slightly reflective lower crust with diffractions and a weak moho signal the southern sector of the pannonian depression is generally marked by a reflective lower crust the tectonic significance of these seismic signatures is interpreted as follows a brittle upper crust a decoupling mid crustal zone a lower crust with brittle to ductile behaviour a possible extensional or isostatic rebalanced moho and laminated zones with reduced viscosities at the lower crust and upper mantle levels a series of crustal models based on the reflection seismic sections are presented for several areas of romania

the role of groundwater in cliff instability an example at cape blanc nez pas de calais france cliff retreat in northern boulonnais is described the distribution of the amount of retreat is related to structural and topographic factors both control the runoff infiltration balance and therefore the mechanical behaviour of the rocks which determines the modes of failure the spatial variability of the retreat rate is explained but predicting the temporal variability of the retreat rate which is central to risk management is much more difficult rainfall and piezometric surface data enhanced a piston flow mechanism during november 2000 the result of its occurrence on the stability of the cliff and conditions of its recurrence are examined with a view to better understanding the rate of recession of coastal cliffs and wiser management of risk copyright 2005 john wiley sons ltd

some geomorphological considerations for the future development of landslide models this paper reviews the commonly available models used to model landslides the main purpose is then to examine some of the wider issues associated with the developments that are required if we are to develop 3 d applications and to extrapolate their use to long time scales the paper does not discuss landslide hazard mapping models but concentrates on the 3 d and temporal problems associated with the modelling of single slides

crust and upper mantle structure in the caribbean region by group velocity tomography and regionalization an overview of the crust and upper mantle structure of central america and the caribbean region is presented as a result of the processing of more than 200 seismograms recorded by digital broadband stations from sssn and gsn seismic networks group velocity dispersion curves are obtained in the period range from 10s to 40s by ftan analysis of the fundamental mode of the rayleigh waves the error of these measurements varies from 0 06 and 0 09 km s from the dispersion curve seven tomographic maps at different periods and with average spatial resolution of 500 km are obtained using the logical combinatorial classification techniques eight main groups of dispersion curves are determined from the tomographic maps and eleven main regions each one characterized by one kind of dispersion curves are identified the average dispersion curves obtained for each region are extended to 150s by adding data from a larger scale tomographic study vdovin et al 1999 and inverted using a nonlinear procedure a set of models of the s wave velocity vs depth in the crust and upper mantle is found as a result of the inversion process in six regions we identify a typically oceanic crust and upper mantle structure while in the other two the models are consistent with the presence of a continental structure two regions located over the major geological zones of the accretionary crust of the caribbean region are characterized by a peculiar crust and upper mantle structure indicating the presence of lithospheric roots reaching at least about 200 km of depth

strong lg wave attenuation in the middle east continental collision orogenic belt abstract using lg wave q tomography we construct a broadband crustal attenuation model for the middle east the q lg images reveal a relationship between attenuation and geological structures strong attenuation is found in the continental collision orogenic belt that extends from the turkish and iranian plateau to the pamir plateau we investigate the frequency dependence of q lg in different geologic formations the results illustrate that q lg values generally increase with increasing frequency but exhibit complex relationships both with frequency and between regions an average q lg value between 0 2 and 2 0 hz q lg 0 2 2 0 hz may be a critical index for crustal attenuation and is used to infer the regional geology low q lg anomalies are present in the eastern turkish plateau and correlate well with low pn velocities and cenozoic volcanic activity thus indicating possible partial melting within the crust in this region very strong attenuation is also observed in central iran the afghanistan block and the southern caspian sea this in line with the previously observed high crustal temperature high conductivity layers and thick marine sediments in these areas suggests the high lg attenuation is caused by abnormally high tectonic and thermal activities

high resolution sequence stratigraphy of a mixed carbonate siliciclastic cratonic ramp upper ordovician kentucky ohio usa insights into the relative influence of eustasy and tectonics through analysis of facies gradients abstract detailed facies analysis and event stratigraphy of an upper ordovician rocklandian edenian cratonic ramp succession in eastern north america yields insights into eustatically driven sequence architecture and localized tectonic instability seven predominantly subtidal mixed carbonate siliciclastic depositional sequences 3rd order are identified and correlated across the length of a 275 km ramp to basin profile within the larger depositional sequences 3rd order at least two smaller orders 4th and 5th of cyclicity are recognizable three systems tracts occur within each sequence transgressive tst highstand hst regressive rst and are considered in terms of their component parasequences 5th order generally tsts are composed of skeletal grainstone rudstone facies hsts are dominated by shaly nodular wacke packstone facies and rsts are mostly calcarenite facies systems tracts sequence boundaries and their correlative conformities maximum flooding surfaces and forced regression surfaces were traced from shallow shelf to basinal settings this high resolution framework also provides insight into the timing of tectonic fluctuations on this cratonic ramp during the taconic orogeny and documents the relative influence of tectonism on lateral facies distributions and eustatically derived cyclicity

sequence stratigraphy in the middle ordovician shale successions mid east korea stratigraphic variations and preservation potential of organic matter within a sequence stratigraphic framework abstract the jigunsan formation is the middle ordovician shale dominated transgressive succession in the taebaeksan basin located in the eastern margin of the north china platform the total organic carbon toc content and some geochemical properties of the succession exhibit a stratigraphically distinct distribution pattern the pattern was closely associated with the redox conditions related to decomposition bulk sedimentation rate dilution and productivity to explain the distinct distribution pattern this study attempted to construct a high resolution sequence stratigraphic framework for the jigunsan formation the shale dominated jigunsan formation comprises a lower layer of dark gray shale deposited during transgression and an upper layer of greenish gray siltstone deposited during highstand and falling stage systems tracts the concept of a back stepped carbonate platform is adopted to distinguish early and late transgressive systems tracts early and late tst in this study whereas the highstand systems tracts and falling stage systems tracts can be divided by changes in stacking patterns from aggradation to progradation the late tst would be initiated on a rapidly back stepping surface of sediments and just above the surface exhibits a high peak in toc content followed by a gradually upward decrease this trend of toc distribution in the late tst continues to the maximum flooding surface mfs the perplexing toc distribution pattern within the late tst most likely resulted from both a gradual reduction in productivity during the late tst and a gradual increase in dilution effect near the mfs interval the reduced production of organic matter primarily incurred decreasing toc content toward the mfs when the productivity was mainly governed by benthic biota because planktonic organisms were not widespread in the ordovician results of this study will help improve the understanding of the source rock distribution in mixed carbonate siliciclastic successions within a stratigraphic framework particularly for unconventional shale reservoirs

geodynamics and intermediate depth seismicity in vrancea the south eastern carpathians current state of the art abstract the vrancea region of the south eastern carpathians is a remarkable site of intra continental intermediate depth seismicity a large set of geological geophysical and geodetic observations has been accumulated for the last few decades and utilised to improve our knowledge of the shallow and deep structures beneath vrancea the crustal and mantle dynamics and the linkage between deep and surface processes in the region in this article we review geology and tectonics of the vrancea region including post collisional to recent deformations syn to post collisional magmatism and orogenic exhumation along the east and south carpathians the regional seismicity is analysed and the recent seismic studies including reflection refraction body and surface wave tomography are reviewed we discuss new geodetic measurements of horizontal and vertical movements in the region geoelectric studies density gravity and thermal modelling qualitative and quantitative including retrospective geodynamic models developed for vrancea are analysed the knowledge of regional tectonics geodynamics seismicity lithospheric deformation and stress regime in the vrancea earthquake prone region assists in an assessment of strong ground motion seismic hazard and risk the earthquake simulation seismic hazard and earthquake forecasting models have also been reviewed providing a link between deep geodynamic processes and their manifestation on the surface finally we discuss unresolved problems in vrancea in order to improve our understanding of the regional evolution present tectonics mantle dynamics intermediate depth seismicity and surface manifestations of the lithosphere dynamics and to enhance our ability to forecast strong earthquakes in the vrancea region the problems to be solved include i the origin of the high velocity body revealed by seismic tomography studies oceanic versus continental ii the lithospheric scale mechanism driving the miocene subsidence of the transylvania basin iii sub crustal structure between 40 and 70 km iv contemporary regional horizontal and vertical movements and v a comprehensive seismic hazard assessment in the region

eurid a regionalized 3 d seismological model of europe abstract this paper presents a 3 d regionalized model of the european crust and mantle velocity structure down to depths of approximately 300 km the model is entirely based upon the existing geological and geophysical literature and it incorporates topographic and bathymetric features the resulting model which we call eurid european i data set consists of approximately 6400 1 d vertical structures having an average separation of about 100 km eurid is compared quantitatively with eur s91 a recent s wave velocity tomographic model obtained from body and surface wave waveform inversion zielhuis a nolet g 1994 shear wave velocity variations in the upper mantle beneath central europe geophys j int 117 695 715 it is found that the s wave velocities in eurid and in eur s91 zielhuis and nolet 1994 do not differ by more than about 4 over most of the area to validate eurid surface wave dispersion analysis is performed along some selected paths the fundamental mode group velocity curves obtained using 1 d average models derived from eurid are found in good agreement with those determined from observations broadband waveform synthetics are also calculated along the same paths and compared with the observed time series overall we believe that eurid is representative of our current knowledge of the crust upper mantle structure beneath europe and it can be used to model realistically ground motion for periods above 10 s within structurally homogeneous regions the first digital version of this structure database is available for public use

can earth s rotation and tidal despinning drive plate tectonics abstract we re evaluate the possibility that earth s rotation contributes to plate tectonics on the basis of the following observations 1 plates move along a westerly polarized flow that forms an angle relative to the equator close to the revolution plane of the moon 2 plate boundaries are asymmetric being their geographic polarity the first order controlling parameter unlike recent analysis the slab dip is confirmed to be steeper along w directed subduction zones 3 the global seismicity depends on latitude and correlates with the decadal oscillations of the excess length of day lod 4 the earth s deceleration supplies energy to plate tectonics comparable to the computed budget dissipated by the deformation processes 5 the gutenberg richter law supports that the whole lithosphere is a self organized system in critical state i e a force is acting contemporaneously on all the plates and distributes the energy over the whole lithospheric shell a condition that can be satisfied by a force acting at the astronomical scale assuming an ultra low viscosity layer in the upper asthenosphere the horizontal component of the tidal oscillation and torque would be able to slowly shift the lithosphere relative to the mantle