empirical observations regarding reverse earthquakes blind thrust faults and quaternary deformation are blind thrust faults truly blind active thrust faults pose a significant seismic hazard worldwide many of these faults include blind thrusts where the propagating fault tip does not reach the earth s surface and buried faults where the geomorphic expression of the fault is obscured by subsequent sedimentation and or erosion this raises the issue of whether conventional geologic geomorphic and paleoseismic methods can be used to identify and characterize thrust faults for the assessment of seismic hazards or whether these faults sometimes are truly blind we compiled a data base of 148 worldwide moderate to large magnitude thrust reverse earthquakes to evaluate whether or not the event occurred on a fault that could have been identified prior to the earthquake on the basis of recognizable quaternary surface deformation i e a pre existing fault or fold analysis of the data shows that interplate reverse earthquakes almost always are associated with pre existing quaternary deformation that was or could have been recognized prior to the earthquake in particular most interplate reverse earthquakes are associated with an active reverse fault at the surface and or an active anticline in contrast intraplate reverse earthquakes seldom occur on faults associated with pre existing recognizable surface deformation we conclude that thrust faults can be detected in interplate regions with careful quaternary geologic and geomorphic mapping furthermore the absence of quaternary surface deformation can be used to infer the absence of an underlying active blind thrust fault in interplate tectonic settings however the data show that quaternary geologic mapping techniques alone likely are insufficient to characterize blind thrusts in intraplate regions in these areas inclusion of a floating or random earthquake may be necessary to assess earthquake hazards

active fault related folding in the epicentral area of the december 25 1222 io ix mcs brescia earthquake northern italy seismotectonic implications abstract a dense grid of petroleum industry seismic reflection profiles coupled with field mapping exploratory trenching and geomorphic and structural analysis are used to characterize the quaternary growth history of the capriano del colle fault system one of several inferred active buried thrusts that extend across the po plain in northern italy shortening is characterized here by a deeply buried south vergent forethrust and an associated north vergent backthrust whose upward propagation is expressed by fault propagation folding near the surface structural interpretation based on seismic data suggests that strain is accommodated at very shallow levels by secondary flexural slip thrusts and reverse faults developed on synclinal flanks that emanate from active axial surfaces analysis of syntectonic growth strata document maximum rates of dip slip of 3 45 0 66 mm yr 1 6 myr 1 2 myr and 0 47 0 22 mm yr during a more recent time period 0 89 myr present a quarry excavation at capriano del colle allows a preliminary paleoseismologic analysis of coseismic surface faulting and liquefaction exposed near the core of an active mid pleistocene to holocene anticline these features are interpreted to be generated during strong local earthquakes consistent with the environmental effects and ground motions of an event similar to the december 25 1222 brescia earthquake io ix mcs this indicates for the first time that compressive folds and blind thrusts in the po plain are currently accommodating slow rates of modern contraction in an active zone of the southern alps that extends from lake garda to varese we thus argue that earthquakes similar to the december 25 1222 brescia event are likely to occur in this region and pose a direct threat to such a densely populated and developed area

seismogenic sources potentially responsible for earthquakes with m 6 in the eastern southern alps thiene udine sector ne italy summary new geomorphological and structural data permitted to define the active faulting framework of the eastern southern alps ne italy all the active faults detected in the investigated area are thrust segments of the complex thrust system which has been responsible for the latest building of the eastern southalpine chain esc geomorphological investigations were performed to identify the surficial traces of recent fault activity generally represented by gentle scarps connecting uplifted palaeolandscapes of quaternary age with the flat and lower areas of the venetian and friulian plains surficial and subsurficial data the latter from reflection seismic profiles available for the investigated faults indicate that the thrusts have been responsible for the displacement of the entire wedge of quaternary deposits in the western sector of the investigated area the six recognized fault segments represent portions of a 100 km long thrust system at the boundary between the alpine relief and the plain areas in the eastern sector active tectonics is the result of parallel thrust segments located both in the alpine mountainous area and in the friulian plain the 3 d geometry of the active thrust segments has been derived from new structural surficial surveys and the interpretation of reflection seismic profiles for a total length of 1700 km on this basis we defined the geometry of 10 seismogenic sources whose dimensions are consistent with the occurrence of earthquakes with m 6 the comparison between the source geometry and the highest intensity data point distribution of large historical earthquakes has permitted to make hypotheses on the association of past seismic events to specific seismogenic sources this procedure indicated that no large historical events can be attributed to three sources montello conegliano arba ragogna medea this may indicate an elapsed time since the last activation of more than eight centuries based on the completeness of the historical catalogues the available data define therefore sources and related areas for which a high level of seismic hazard may be invoked

tidal distortions and flood dominance at five small tidal inlets in southern maine maximum and mean flood current velocities exceeded ebb current velocities by an average of more than 20 cm s 1 at five small inlets along the southern coast of maine distortion of the tidal wave as it interacts with these shallow inlets such that the rising tide duration averages 3 22 h less than the falling tide duration may be the cause of flood current dominance at these inlets tide records from three locations at ogunquit inlet located along the southern coast of maine show that the 29 day average tide duration asymmetry increases from a rising tide that is 0 07 h longer than the falling tide for the offshore record to a rising tide that is 2 15 and 5 15 h shorter than the falling tide for the inlet throat and bay records respectively previous field studies and numerical models of tidal asymmetry have not examined tidal distortion in very shallow inlets where the channels shoal to depths shallower than the forcing tide amplitude at the inlets investigated in this paper channels are shallower than the ocean tide amplitude by an average of 30 cm a model is presented that explains how the shallow inlet bathymetry truncates the ocean tide and produces an inlet tide characterized by an extended falling tide and a shortened rising tide duration the dominance of flood tidal currents at these inlets produces net landward sediment transport

geomorphological variability among microtidal estuaries from the wave dominated south african coast abstract over 300 independent river outlets exist around the microtidal wave dominated south african coast most of these are located in drowned river valley settings and have acquired their present morphology during the holocene marine transgression a variety of geomorphological forms are identified in these estuaries that result from variation in antecedent topography fluvial sediment supply and marine sediment supply five distinctive estuary types are identified on the basis of contemporary morphodynamics these are categorised into three types of normally open estuary that maintain a semi permanent connection with the open sea and two types of normally closed estuary which are separated from the sea for long periods by a continuous supratidal barrier the contemporary morphodynamics and sedimentary environments of each estuary type are discussed open estuaries include barrier inlet systems maintained by fluvial discharge termed river dominated estuaries and tidal discharge termed tide dominated estuaries a third category of open estuary lacks a supratidal barrier due to inadequate marine sediment availability closed estuaries receive marine influence via barrier overwash and occasional breaching but are typically enclosed behind a continuous supratidal barrier two categories of closed estuary are identified perched and non perched perched estuaries develop behind high berms and maintain a water level above high tide level in the open sea they are often dominated by fresh to brackish water and breach and drain periodically non perched estuaries are developed behind low elevation barriers fronted by wide dissipative beach profiles high overwash frequency introduces marine water into such systems breaching of such estuaries does not produce dramatic draining as the water level may only drop according to the stage of the open sea tidal cycle the variety of estuary types suggests several potential pathways may exist in estuarine development and that the progressive infilling model is an over simplification

teleseismic time functions for large shallow subduction zone earthquakes broadband vertical p wave records are analyzed from 63 of the largest shallow subduction zone earthquakes which have occurred in the circum pacific in the last 45 yr most of the records studied come from a common instrument the pasadena california benioff 1 90 seismometer propagation and instrument effects are deconvolved from the p wave records using a damped least squares inversion to obtain the teleseismic source time function the inversion has the additional constraint that the time function be positive everywhere the period band over which the time functions are considered reliable is from 2 5 to 50 sec fourier displacement amplitude spectra computed for each of the 1 90 p wave trains indicate spectral slopes measured between 2 and 50 sec of 1 0 to 2 25 with an average value of 1 5 these values assume an average attenuation of t 1 0 the seismic moments derived from the p wave time functions compare well with other published values for earthquakes having moments smaller than 2 5 10 28 dyne cm m w 8 2 because the 1 90 seismometer has little response at very long periods this technique underestimates the moments of the very largest events the time functions are characterized using five parameters 1 spectral slope between 2 and 50 sec 2 roughness of the time function 3 multiplicity of sources 4 pulse widths of individual sources and 5 overall signal duration the 63 earthquakes studied come from 15 subduction zones with a wide range in the ages of subducted lithosphere convergence rates and maximum size of earthquakes comparing the time function parameters with age rate and m w of the subduction zone does not yield obvious global trends however most of the subduction zones do behave characteristically and can be grouped accordingly

time intervals to assess active and capable faults for engineering practices in italy abstract the time span necessary to define a fault as active and capable can mainly be derived from the framework of the regulations and the literature produced since the 1970s on risk estimation in engineering planning of strategic buildings within this framework two different lines of thought can be determined which have mainly developed in the usa on the one side there is a tendency to produce narrow chronological definitions this is particularly evident in the regulatory acts for the planning of nuclear reactors the much more effective second line of thought anchors the chronological definitions of the terms active and therefore capable to the concept of seismotectonic domain as the domains are different in different regions of the world the chronological definition cannot be univocal i e different criteria are needed to define fault activity which will depend on the characteristics of the local tectonic domain and of the related recurrence times of fault activation current research on active tectonics indicates that methodological aspects can also condition the chronological choice to define fault activity indeed this practice implies the use of earth science methods the applications of which can be inherently limited for example limits and constraints might be related to the availability of datable sediments and landforms that can be used to define the recent fault kinematic history for the italian territory we consider two main tectonic domains a the compressive domain along the southern margin of the alpine chain and the northern and northeastern margins of the apennines which is characterised by the activity of blind thrusts and reverse faults and b the extensional domain of the apennines and the calabria region which is often manifest through the activity of seismogenic normal and normal oblique faults in case a the general geomorphic and subsurficial evidence of recent activity suggests that a reverse blind fault or a blind thrust should be considered active and potentially capable if showing evidence of activity during the quaternary i e over the last 2 6 myr unless information is available that documents its inactivity since at least the last glacial maximum lgm ca 20 ka the choice of the lgm period as the minimum age necessary to define fault inactivity is related to practical aspects the diffusion of the lgm deposits and landforms and to the evidence that ca 20 kyr to assess fault inactivity precautionarily includes a number of seismic cycles in the extensional domains of the apennines and calabria region the general geological setting suggests that the present tectonic regime has been active since the beginning of the middle pleistocene therefore we propose that a normal fault in the italian extensional domain should be considered active and capable if it displays evidence of activation in the last 0 8 myr unless it is sealed by deposits or landforms not younger than the lgm the choice of the lgm as the minimum age to ascertain fault inactivity follows the same criteria described for the compressive tectonic domain

stratigraphic evidence for a pluvial phase between ca 8200 7100 ka from renella cave central italy a stratigraphic and chronological study of the upper level of renella cave apuan alps central italy reveals that two episodes of flowstone accumulation bracket a thick clastic layer deposited between ca 8 2 and 7 1 ka this layer which represents a period of enhanced cave flooding is substantially in phase with an interval of depleted oxygen isotope values previously recorded in a stalagmite from nearby corchia cave interpreted to have resulted from an increase in local precipitation these data confirm that during this period of time the region experienced relatively wetter conditions including an increase in high magnitude events capable of invading the higher passages of renella cave the timing of the clastic phase occurred when the eastern mediterranean experienced deposition of sapropel layer s1 which is thought to reflect the stagnation of sea water produced largely by enhanced flood activity along the nile in response to increased monsoon intensity in northern equatorial africa recent estimates suggest that s1 may have lasted from ca 10 8 to ca 6 1 ka cal bp combined evidence from renella and corchia cave indicates that the period corresponding to the wettest phase in the apuan alps was much shorter than this and suggests that there is no straightforward connection between increased advection of water vapour from the atlantic between 8 2 and 7 1 ka as recorded in the corchia and renella records and monsoon driven enhancement of nile discharge and s1 deposition in the eastern mediterranean

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

integrated micropaleontological study of the messinian diatomaceous deposits of the monferrato arc piedmont basin nw italy new insights into the paleoceanographic evolution of the northernmost mediterranean region abstract the upper miocene diatom bearing section of pecetto di valenza piedmont nw italy represents a unique site for reconstructing the paleoceanographic processes that occurred before the onset of the messinian salinity crisis in the northernmost mediterranean basin the combined analysis of foraminifera calcareous nannofossils diatoms and other siliceous microfossils observed in the marly and diatomaceous sediments allowed us to define four main evolutionary stages of the biogenic sedimentation each stage was typified by specific water column and seafloor conditions tentatively correlated to the precession insolation variability in particular the variation of the benthic assemblages allowed us to distinguish two stages in the evolution of the diatomaceous deposition which would be otherwise impossible from the lithology the accumulation of the diatomaceous sediments was likely controlled by the interplay between riverine runoff water column stratification and convective mixing rather than with upwelling and seafloor anoxia as inferred for the western and eastern sectors of the mediterranean

centroid single force inversion of seismic waves generated by landslides the centroid moment tensor cmt waveform inversion method of dziewonski et al 1981 is modified to analyze long period seismic waves generated by single force events such as the gigantic landslides associated with the 1980 eruption of mount st helens we refer to the method as centroid single force csf inversion as the result of the inversion we obtain the spatio temporal centroid and three components of a vector we call the csf vector which is the seismic point source representation of a landslide and whose direction is the opposite of the direction of sliding the sealer magnitude of the csf vector measures the overall size of the landslide and is given by mcsf md where m is the mass of the sliding object and d is the sliding distance we apply csf inversion to the long period surface waves generated by the 1980 mount st helens event the 1975 kalapana earthquake and the 1974 mantaro landslide using seismograms from the gdsn ida and hglp networks the csf solution for the st helens event is remarkably consistent with the actual geological observations and proves the efficacy of csf inversion the csf solution for the kalapana event does not fit the overall waveforms better than the cmt solution does however because the cmt solution does not explain the observed love wave radiation pattern it may be necessary to invoke a combination of both types of mechanism for this event although the geometry of the csf solution the direction of the force for the mantaro event is consistent with the actual landslide mcsf is about 5 times smaller than that expected from the mass and travel distance of the landslide estimated by geological observations this discrepancy may suggest either the relatively aseismic nature of this landslide or that the total volume of the slide was overestimated by analogy to single station cmt inversion single station csf inversion also appears to be stable and useful

first evidence for late pleistocene to holocene earthquake surface faulting in the eastern monferrato arc northern italy geology pedostratigraphy and structural study of the pecetto di valenza site abstract the w po plain northern italy is commonly regarded as a region characterized by a low seismicity hazard due to the lack of historical and instrumental record of strong earthquakes nevertheless recent studies performed in the monferrato hills provide evidence of active faulting and possible paleoseismicity occurred in middle pleistocene to holocene times therefore for verifying the seismic potential of this area we firstly revised the available geological and geophysical information we selected the area between valenza and alessandria eastern monferrato arc which show the best structural geomorphic and stratigraphic setting for documenting recent tectonic deformation and faulting therein we identified for the first time evidence for earthquake surface displacement in a late quaternary pedosedimentary sequence exposed at pecetto di valenza the outcropping section has been logged and investigated according to an approach integrating sedimentological and micropedological data with structural analyses and radiocarbon dating this allowed reconstructing the recent surface evolution and the paleoseismic history of the site from the bottom the pedosedimentary sequence consists of a miocene marly bedrock whose weathering started in marine isotopic stage mis 7 or 5 interglacials a colluvial deposit follows whose formation can be attributed to mis 5e the upper part of the sequence consists of two loess covers showing different degrees of weathering possibly occurred at ca 30 ka bp for the deepest loess and in the middle holocene ca 4 ka bp for the uppermost one the loess accretion is therefore older and likely associated to the mis 3 and mis 2 glacial phases each deposit records the deformation induced by earthquake surface reverse faulting and warping giving constraints to the sequence of events that characterized this site in fact the structural analyses and a 2d balanced retrodeformation of the section integrating pedostratigraphic constraints allowed identifying at least two different phases of deformation and more than five fault scarp forming events which caused a total net displacement of ca 4 8 m during the past ca 40 ka our approach highlighted the interaction between the tectonically induced surface deformation and the aeolian deposition allowing reconstructing the recent evolution of a small drainage basin the results of this paleoseismic analysis reinforce the conclusion of previous authors that the monferrato arc should be viewed as a seismic gap characterized by strong earthquakes mmax 6 5 with long recurrence interval in the order of several thousands years this evidence has relevant implications for seismic hazard assessment which must be checked with further trench investigations along the mapped quaternary thrust faults affecting the western part of the po plain

polycyclic luvisols in northern italy palaeopedological and clay mineralogical characteristics abstract two long pleistocene palaeosol sequences in the southwestern fringe of the lago maggiore region northern italy were studied by a wide range of pedological methods particular emphasis was placed on clay mineralogy in order to distinguish the weathering intensity of different palaeosols the clay mineralogical analyses showed a gradual transformation from the top to the central part of the studied sequences whereas the uppermost horizons include chlorite as a sign of weak alteration processes the underlying palaeosols are dominated by vermiculites and mixed layers the lowermost parts of the palaeosol sequences show different conditions as they contain neoformed kaolinite paleosols and pedocomplexes were correlated by mean of their pedologicial characteristics six main pedogenetic units have been identified in both sequences representing different stages of soil formation paleopedological and clay mineralogical results indicate at least four interglacial phases two of them showing warmer and more humid conditions than today and two of them showing climatic conditions comparable with the present day climate

analysis of long period seismic waves excited by the may 18 1980 eruption of mount st helens a terrestrial monopole long period 100 to 260 s love and rayleigh waves excited by the eruption of mount st helens on may 18 1980 and recorded by ida sro and asro stations were analyzed to determine the mechanism of the eruption the amplitude radiation patterns of both rayleigh and love waves are two lobed with a nodal direction in e5 s for rayleigh waves and in n5 e for love waves these radiation patterns preclude any double couple mechanism the radiation pattern the initial phase the relatively large amplitude ratio of love to rayleigh waves and the existence of clear nodes in the radiation patterns of fundamental mode and higher mode rayleigh waves suggest that the source is represented by an almost horizontal less than 15 from the horizontal single force pointed toward s5 w the surface wave spectra fall off very rapidly at periods shorter than 75 s suggesting a very slow source process although the details of the source time history could not be determined a smooth bell shaped time function f o s t 1 2 f o l cos t for 0 t 2 and f o s t 0 for t 2 with 75 s is considered appropriate on the basis of comparison between synthetic and observed seismograms and of the shape of the source spectrum the peak value of the force f 0 is about 10 18 dynes the tailing end of the source time function could not be resolved and some overshoot may be added the magnitude and the time history of the force can be explained by a northward landslide followed by a lateral blast observed at the time of the eruption two distinct events about 110 s apart can be identified on body wave and short period surface wave records the first event may correspond to the earthquake which triggered the landslide and the lateral blast the second event appears to correspond to a second large earthquake and explosion which took place about 2 minutes after the first earthquake

micromorphological approach to polycyclic pedogenesis on the messak settafet plateau central sahara formative processes and palaeoenvironmental significance the messak settafet is a wide plateau located in the libyan central sahara sw fezzan it is cut into the nubian sandstone and interpreted as relic of a tertiary peneplain heavily affected by aeolian deflation notwithstanding degradation phenomena discontinuous thin soil bodies are locally preserved below the hamada several profiles located in correspondence of different geomorphological units the hamada the endorheic depressions and the southern escarpment were described and sampled for micropedological analyses micromorphology outlined that the main characteristics of the residual b horizons from each geomorphological units are i high concentration of ferruginous nodules ii multiple generations of clay illuviation iii fragmentation and deformation of textural pedofeatures and iv calcite mobilization and redeposition according to horizon macro and micromorphological characteristics these pedologic bodies do not seem to be in equilibrium with the present day climatic conditions and should be regarded as paleosols generated by processes regulated by large water availability and warm temperature such as rubification clay translocation and calcite redistribution the development of horizons acted mainly since the early middle pleistocene during subsequent pluvial periods and was interrupted by several erosional and aeolian input phases arid periods pedological processes ended at the onset of the severe dry environmental conditions at the mid late holocene transition the development of this kind of paleosols in the central sahara is also discussed in comparison with pedogenetic processes occurring in temperate regions during interglacial and interstadial intervals

episodic closure of the tidal inlet at the mouth of the russian river a small bar built estuary in california bar built estuaries with relatively small cross sectional area 100 m2 and shallow tidal inlets are widespread in mediterranean climates and along wave exposed coasts while similarly important to coastal sediment balances and estuarine ecosystems and more numerous than larger inlet systems they suffer from a relative lack of understanding this is especially true regarding the process of inlet closure when the channel is filled with sediment deposited by wave driven processes mouth closure is of growing concern owing to changes in inlet behavior in many systems in response to human influences the use of many existing conceptual and quantitative models for closure is precluded by rapid morphological change unsteady freshwater inputs and difficulties in scaling well established inlet relationships in these smaller systems in this paper over 60 years of daily closure records are analyzed for the russian river mouth a prototypical bar built system in northern california we show that the time dependent closure pattern can be explained by an interaction of processes that act to scour the inlet driven by tides and river with those that act to deposit sand in the inlet driven by waves tidal weather related seasonal and interannual cycles are observed we improve an existing parametric model to evaluate these separate influences and show that it works well for predicting closure events at both the tidal and seasonal scales finally we compare our data with closure records from the nineteenth and twentieth centuries to show that inlet closures have become shorter and more sporadic over time at this site and to identify anthropogenic drivers of this observed change

tests of selected sediment transport formulas eleven existing sediment transport formulas were tested against the field data measured at two united states geological survey usgs gauging stations along the sacramento river in california whose bed material sizes are classified as those ranging from fine sand to coarse gravel they include the ackers white einstein brown engelund fredsoe engelund hansen inglis lacey karim meyer peter and mueller rijin schoklitsch toffaleti and yang formulas general flow and sediment input variables required by each transport function as well as dependent variables are summarized and detailed and measured hydraulic and sediment quantities including bed material size distributions are presented the computed sediment discharges are tabulated for comparison and are directly compared against the measured suspended sediment discharges the computed values however are found to deviate significantly from the measured values except for a very few cases the test results clearly demonstrate how difficult a ta

slab decoupling in the tonga arc the june 22 1977 earthquake the june 22 1977 earthquake in the southern tonga arc is a large normal faulting event with downdip rupture propagation on a steeply dipping fault plane we use a standard least squares inversion of p and sh waves for the source time function to determine a source consisting of two subevents located at depths of 40 55 and 105 125 km and a total time duration of 50 s the ratios of the spectral amplitudes of the radial modes 0s0 1s0 and 2s0 independently require a centroid depth of at least 100 km at their lower frequencies the body wave analysis suggests a moment of 1 04 1028 and the 0s0 spectral amplitude suggests a value of 1 8 2 0 1028 dyn cm the emerging picture is that of a complete rupture of the sinking lithospheric slab starting from 40 km depth and propagating down to 125 km this indicates that the decoupling of the overriding lithosphere from the slab in this area of the tonga arc takes place by gravitational pull

depth distribution of moment release in underthrusting earthquakes at subduction zones we present a global analysis of the depth distribution of moment release along the thrust contact at subduction zones using data from harvard s centroid moment tensor catalogue substantial regional variations in the depth distribution of moment release are observed a significant correlation exists between the depth of maximum moment release and the convergence rate of subducting lithosphere and the sediment thickness at the trench subduction zones with fast convergence rates and thick sediment accumulations concentrate moment release at greater depths than subduction zones with slow convergence rates and little sediment accumulation the correlation between the convergence rate of oceanic lithosphere and the depth distribution of moment release may be best explained by differences in the thermal structure of the plate interface subduction zones with fast convergence velocities transport cold material to greater depths than subduction zones with slow convergence velocities the colder temperature of the deep portions of the thrust contact at subduction zones with fast convergence velocities allows seismic failure to occur at greater depth than possible in subduction zones with slow convergence velocities as has been demonstrated in intraplate environments our observations in interplate thrust settings support the idea that temperature is the most important factor controlling the maximum depth of seismic failure in subduction zones with thick sediment accumulations the stable sliding properties of unconsolidated sediments may be responsible for the low levels of shallow moment release

sedimentation in a fluvially infilling barrier bound estuary on a wave dominated microtidal coast the oueme river estuary benin west africa the oueme river estuary is located on the seasonally humid tropical coast of benin west africa a striking feature of this microtidal estuary is the presence of a large sand barrier bounding a 120 km2 circular central basin lake nokoue that is being infilled by heterogeneous fluvial deposits supplied by a relatively large catchment 50 000 km2 borehole cores from the lower estuary show basal pleistocene lowstand alluvial sediments overlain by holocene transgressive highstand lagoonal mud and by transgressive to probably early highstand tidal inlet and flood tidal delta sand deposited in association with non preserved transgressive sand barriers the change in estuary mouth sedimentation from a transgressive barrier inlet system to a regressive highstand barrier reflects regional modifications in marine sand supply and in the cross barrier tidal flux associated with barrier inlet systems as barrier formation west of the oueme river led to an increasingly rectilinear shoreline the longshore drift cell matured ensuring voluminous eastward transport of sand from the volta delta in ghana the major purveyor of sand to the oueme embayment 200 km east concomitantly the number of tidal inlets and the tidal flux associated with a hitherto interlinked lagoonal system on this coast diminished complete sealing of lake nokoue has produced a large permanently closed estuary where tidal intrusion is assured through the interconnected coastal lagoon via an inlet located 60 km east since 1885 tides have entered the estuary directly through an artificial outlet cut across the sand barrier although precluding the seaward loss of fluvial sediments permanent estuary mouth closure has especially deprived the highstand estuary of marine sand a potentially important component in estuarine infill on wave dominated coasts in spite of a significant fluvial sediment supply estuarine infill has been moderate because of the size of the central basin estuarine closure has resulted in two co existing highstand sediment suites with limited admixture the marine derived estuary mouth barrier and upland derived back barrier sediments this situation differs from that of mature barrier estuaries characterized by active fluvial marine sediment mixing and facies interfingering

three dimensional seismo tectonics in the po valley basin northern italy the po valley northern italy is a composite foreland foredeep basin caught in between the southern alps and northern apennine mountain belts by integrating the 3d structural model of the region with the public earthquake dataset the seismo tectonics of the basin is shown at different scales of observation the three dimensional geo volumeis used to reviewthe seismicity around the region and validate the structure earthquake association for such a complex tectonic framework despite the overall uncertainty due to the original data distribution quality as well as the crustal scale model dimension the direct correlation between structures and seismicity a confirms the po valley region as an active tectonic system and b allows the whole structural architecture to be revised by a unique three dimensional perspective and approach this study also indicates that 3d methodology is a powerful tool for better understanding of highly complex seismo tectonic situations at both regional and local scales

loess in italy genesis characteristics and occurrence abstract there is currently a renewed interest in loess genesis and occurrence in italy well known loess profiles in northern italy have been re examined and previously unknown loess deposits in central and southern italy have been reported this work combines a meta analysis of published data with new data presented here for the first time to provide the state of the art on the spatial distribution characteristics genesis and deposition ages of loess in italy a database of 98 soil horizons from 91 soil profiles was created and made available it stores information on soils formed from loess or containing layers that show admixture of loess soil data include the source of information the topographic geomorphological and geological setting kind of parent material and land use main soil horizon properties as described in the field soil classification particle size distribution and chemical data loess is reported from almost all regions of italy it is generally pedogenized throughout the entire loess body and forms the parent material of deep and complex soil profiles the thickness of the loess deposits varies from a few decimeters to a few meters pedogenesis and local reworking partially change the original loess characteristics in this study we propose a set of parameters that help recognizing loess in soils particle size distribution and sorting geomorphological setting pedostratigraphic position shape of the grains under optical and scanning electron microscope sem and soil micromorphological characteristics the ages of the loess deposits range between 70 ka bp and 18 ka bp there are also a number of samples that have been dated to the holocene the meta analysis suggests that climate is not the only driver of loess deposition in italy geomorphological instability and human disturbance as well as the influence of saharan dust most likely played major roles too this study demonstrates that loess is much more widespread in italy than previously estimated yet further research on the spatial and temporal distribution of loess deposition across the mediterranean region is needed to better understand its genesis sources and trajectories periods of enhanced loess formation and the role of loess deposits in ecosystem functioning and resilience

the upper miocene diatomaceous sediments of the northernmost mediterranean region a lamina scale investigation of an overlooked palaeoceanographic archive

sediment transport under wave and current combined flows on a tide dominated shoreface northern coast of france abstract hydrodynamic circulation and sediment transport patterns were investigated on a macrotidal shoreface off the southern north sea coast of france from in situ directional wave and current measurements and through numerical modeling of sediment flux current meters equipped with wave gauges were deployed at two sites on the mid upper shoreface in approximately 5 6 m water depth during 6 and 15 days sediment flux was estimated using the sedtrans96 numerical model li m z amos c l 2001 sedtrans96 the upgraded and better calibrated sediment transport model for continental shelves comp geosc 27 619 645 based on grant and madsen s grant w d madsen o s 1986 the continental shelf bottom boundary layer ann rev fluid mech 18 265 305 combined flow boundary layer theory the hydrodynamic measurements and modeling results show that sediment on the shoreface is essentially transported alongshore in response to shore parallel tidal currents the direction of the net sediment transport is largely determined by the asymmetry of the tidal flows which can be flood or ebb dominated but during important wind speed events winds blowing in the same direction as tidal flow can significantly reinforce tidal currents or conversely can limit tidal current speeds when acting in the opposite direction although sediment transport on this macrotidal shoreface is strongly controlled by tidal processes waves can significantly enhance bed shear stresses resulting in increased sediment remobilization and hence higher sediment flux wave induced onshore sediment transport may occasionally occur but is several orders of magnitude lower than longshore transport this macrotidal shoreface is thus characterized by a hydraulic regime strongly dominated by shore parallel tidal flows that favour longshore sediment dispersal rather than shore normal transport our results imply that the water depths from which sediment may be transported shoreward to beaches is certainly much more restricted on a macrotidal shoreface such as the one bordering the northern coast of france than on micro and mesotidal shoreface environments where weaker tidal currents do not significantly limit cross shore sediment movements

on tsunami nucleation ii an instantaneous modulated line source abstract tsunami generation on a spherically symmetric self gravitating and elastic earth is investigated using normal mode summations and moment tensor line sources wave cancellation in a line source of length l substantially eliminates tsunamis whose horizontal wavenumber component along the fault exceeds 3 l this results in a preferential beaming of tsunami radiation perpendicular to the fault strike beaming from a source of fixed length occurs in the same fashion irrespective of slip mechanism tsunami radiation patterns from finite sources are thus more uniform than those from point sources the largest far field sea waves from any long shallow fault are likely to be found within 20 azimuth of the perpendicular bisecting great circle although line sources subordinate distinctions in radiation patterns focal mechanism is still a critical element in determining the extent of tsunami excitation the ratio of maximum tsunami amplitude from strike and dip slips of equal moment are 1 10 for faults 400 km in length finite faulting weakens strike slip tsunamis relative to dip slip tsunamis because the beaming and natural radiation directions of strike slips are severely misaligned using an empirical relation linking source process time fault length and moment i predict tsunami energies in the range 1010 1017 j for earthquake moments spanning 2 1018

crustal velocity field of western europe from permanent gps array solutions 1996 2001 we derive a new geodetic velocity field for western europe and the western mediterranean by rigorously combining 1 a selection of 36 itrf2000 sites 2 a solution from a subset of sites of the european permanent gps network euref epn 3 a solution of the french national geodetic permanent gps network rgp and 4 a solution of a permanent gps network in the western alps regal the resulting velocity field describes horizontal crustal motion at 64 sites in western europe with an accuracy of the order of i mm yr 1 or better its analysis shows that central europe defined as east of the rhine graben and north of the alps and the carpathians behaves rigidly at a 0 4 mm yr 1 level and defines a stable europe reference frame in that reference frame we find no significant motion at sites located west of the rhine graben and on the iberian peninsula which sets an upper bound of 0 6 mm yr 1 on horizontal motion across the rhine graben and the pyrenees we find that the current strain pattern in the western alps combines e w extension and right lateral shear we confirm a counterclockwise rotation of the adriatic microplate which appears to control the strain pattern along its boundaries in the friuli area the alps and the apennines our results also suggest that the africa eurasia plate motion in the western mediterranean may be 40 50 per cent slower that the nuvel1a plate motion model and rotated 20 30 counterclockwise

morphostructural evidence of late quaternary tectonics at the po plain northern apennines border lombardy italy abstract the landscape of foreland basins adjacent to active mountain ranges evolves under the control of basinward tectonic propagation of the structural fronts in competition with climate dynamics the resulting palimpsest landscapes record the sequence of geomorphic evolutionary steps and the spatial temporal relations between the active geological processes however a precise evolutionary sequence is hard to decipher from low relief settings like the wide alluvial plains worldwide about these topics we investigate the sequence of tectonic and climate driven processes which shaped the palimpsest landscape of a large quaternary foreland basin the po plain in northern italy above the average glacio fluvial and alluvial plain of the basin late quaternary intra basin reliefs emerge owing to syndepositional ramp folding and uplift driven by n wards propagation of the outermost thrust fronts of the active n apennine chain the incremental tectono morphological and depositional history of the region permits to describe the propagation of the structural front as a polyphase process involving uplift wrenching and late collapse of the reliefs this history is documented by relicts of uplifted planation surfaces covered by latest pleistocene weathered loess units polygonal facets landslides and slope wedges along faults delineating the slopes of the largest among the intra basin reliefs san colombano hill hydrographic anomalies on the relief network river diversions piracy and perching of valleys paleovalley fills river diversions and cross cut relations on the adjacent alluvial plain these features testify the thrust fold related pre lgm uplift of the late pleistocene alluvial stratigraphy the subsequent segmentation of the relief in differently uplifting blocks along riedel faults owing to activation of a transfer fault zone and the lgm extensional collapse of the relief along inherited fault systems a late post glacial outwards propagation of the apennine thrusts was buttressed by the opponent alpine thrust belt front and induced the entrenchment of the river network river diversions on the plain were controlled by the orientation of the san colombano hill fault systems the distribution of historical earthquakes and the present day geodetic data are coherent with this evolution the study documents how in foreland basins the syndepositional propagation of blind orogenic fronts shapes the palimpsest landscape with superimposed morphological tectonic and stratigraphic features of paleoseismic significance and permits comparisons with the other low relief basin settings worldwide

enhanced rainfall in the western mediterranean during deposition of sapropel s1 stalagmite evidence from corchia cave central italy a stable isotope record from a stalagmite collected from antro del corchia cave apuan alps central italy supported by 17 uranium series ages indicates enhanced regional rainfall between ca 8 9 and 7 3 kyr cal bp at the time of sapropel s1 deposition within this phase the highest rainfall occurred between 7 9 and 7 4 kyr cal bp comparison with different marine and lake records and in particular with the soreq cave record israel suggests substantial in phase occurrence of enhanced rainfall between the western and eastern mediterranean basins there is no convincing evidence for major climatic change at the time of the 8 2 kyr event

a hydrologic and geomorphic model of estuary breaching and closure abstract to better understand how the hydrology of bar built estuaries affects breaching and closing patterns a model is developed that incorporates an estuary hydrologic budget with a geomorphic model of the inlet system erosion of the inlet is caused by inlet flow whereas the only morphologic effect of waves is the deposition of sand into the inlet when calibrated the model is able to reproduce the initial seasonal breaching seasonal closure intermittent closures and breaches and the low streamflow closed state estuary hydrology of the carmel lagoon located in central california model performance was tested against three separate years of water level observations when open during these years the inlet was visually observed to drain directly across the beach berm in accordance with model assumptions the calibrated model predicts the observed 48 h estuary stage amplitude with root mean square errors of 0 45 m 0 39 m and 0 42 m for the three separate years for the calibrated model the probability that the estuary inlet is closed decreases exponentially with increasing inflow streamflow plus wave overtopping decreasing 10 fold in probability as mean daily inflow increases from 0 2 to 1 0 m 3 s seasonal patterns of inlet state reflect the seasonal pattern of streamflow though wave overtopping may become the main hydrologic flux during low streamflow conditions infrequently causing short lived breaches in a series of sensitivity analyses it is seen that the status of the inlet and storage of water are sensitive to factors that control the storage transmission and inflow of water by varying individual components of the berm system and estuary storage the amount of the time the estuary is open may increase by 57 or decrease by 44 compared to the amount of time the estuary is open during calibrated model conditions for the 18 2 year model period the individual components tested are berm height width length and hydraulic conductivity estuary hypsometry storage to stage relationship two factors that control wave swash sedimentation of the inlet and sea level rise the elevation of the berm determines the volume of water that must enter the estuary in order to breach and it modulates the wave overtopping flux and frequency by increasing estuary storage capacity the estuary will breach less frequently 27 change in time open for modeled excavation scenario and store water up to 3 months later into the summer altering beach aquifer hydraulic conductivity affects inlet state and patterns of breaching and water storage as a result of sea level rise of 1 67 m by 2100 and a beach berm that remains in its current location and accretes vertically the amount of time the estuary remains open may decrease by 44 such a change is an end member of likely scenarios given that the berm will translate landwards model results indicate that the amount of time the estuary is open is more sensitive to changes in wave run up than the amount of sand deposited in the inlet per each overtopping wave

iterative deconvolution of complex body waves from great earthquakes the tokachi oki earthquake of 1968 abstract a method of body wave inversion is developed in an attempt to extract the information about asperities or barriers in a fault zone a sequence of point sources each being characterized with the seismic moment the onset time and the location are iteratively derived from observed records at multi stations where the two dimensional extent of the source location is taken into account a modification is made of the iterative method of kikuchi and kanamori on the formulation of inversion procedure to facilitate the computation using this method we analyse long period p waves of the tokachi oki earthquake of 1968 mw 8 2 and obtain several significant subevents with time durations of 10 s their spatio temporal distribution shows that the rupture process consists of three characteristic stages a a stage of introductory rupture b a stage of main rupture and c a stage of aftershocks the main rupture takes place in the form of clustering around a few sites of the fault plane the largest subevent occurs in the northwestern corner the stress drop associated with this event is estimated to be 200 bars one order of magnitude higher than the stress drop averaged over the entire fault plane the sum of the seismic moments of the individual subevents amounts to 2 3 1028 dyn cm which approximately coincides with the one estimated from the analysis of long period surface waves this implies that the source of the tokachi oki earthquake consists of several major subevents with time durations of 10 s in addition to other minor subevents

pedogenesis of plinthite during early pliocene in the mediterranean environment case study of a buried paleosol at podere renieri central italy abstract a complex buried paleosol at podere renieri at montalcino central italy formed during a series of continental episodes within an interval of pliocene marine sediments from about 4 1 to 4 8 my bp the aim of this work was to document the kind of pedogenesis which occurred throughout this time and in particular the plinthite formation plinthite soft and hard is poor in organic carbon neutral or subalkaline dominated by illite and enriched in iron and chromium the main differences between soft and hard plinthite are attributed to soil structure which is absent in hard plinthite and to the abundance of iron depleted zones which are much larger in soft plinthite variations in mineralogy chemistry and genesis of soft and hard plinthite can be ascribed to the specific environment of plinthite formation close to the pliocene sea pedogenetic evidence indicates that plinthite evolved in a hot and humid paleoclimate showing a progressive increase in seasonality and that low grade plinthite formation occurred in a time span of a few hundred thousand years soils with low grade plinthite have agronomic value in their suitability for the production of high quality brunello di montalcino wine

geomorphic evidence for an emergent active thrust along the edge of the po plain the broni stradella fault 1 we present here geomorphic evidence for an emergent active thrust along the northwestern apennine front about 50 km south of milano fieldwork combined with spot image analysis attests to the presence of a 35 km long en echelon cumulative fault scarp that cuts e w across quaternary surface deposits from casteggio to sarmato the scarp offsets vertically alluvial fans and terraces emplaced by tributaries of the po river that flow northward from the apennines incision by such tributaries occurs only south of the scarp valleys of smaller streams stand in hanging position to the northeast the buried east dipping pavia lateral ramp bounds the san colombano anticline we interpret the montebello sarmato scarp to result from the emergence of an active thrust fault dipping south the stradella thrust which splays eastward from that ramp total station profiles leveled perpendicular to the stradella thrust show variable cumulative surface throws ranging from 2 to 25 m scarp degradation analysis indicates fairly recent offset of the terrace surfaces 10 100 kyr suggesting a minimum uplift rate of 0 3 mm yr the underlying fault might thus be one of the most active thrust ramps along this segment of the apennines n s to n15 w shortening is consistent with both the e w strike of this thrust ramp and with coeval oblique sinistral motion on the nne ssw trending pavia lateral ramp the vogherese bobbiese earthquake of 1828 i ix south of casteggio and broni may have activated one segment of this lateral ramp rather than the stradella thrust other historical events i 7 that caused damage in pavia piacenza lodi and milano in the last 2000 years 290 a d 1249 a d 1276 a d 1473 a d may have occurred on the broni stradella thrust or on the blind san colombano and lodi thrusts farther north this makes detailed paleoseismological studies and trenching across its trace mandatory

morphodynamics of intermittently open closed coastal lagoon entrances new insights and a conceptual model abstract ocean entrances to coastal lakes and lagoons are a complex sensitive and important part of the coastal environment they provide estuarine water exchange between inland waterways and the open ocean and are increasingly the focus of intense urban and industrial development coastal lagoons that are only intermittently connected to the ocean are particularly sensitive during periods of closure water quality issues are exacerbated along with the increased risk of flooding mechanical clearance was undertaken in 2006 at the ocean entrance to narrabeen lagoon sydney australia historically this site has intermittently opened and closed both naturally and mechanically with the ingress of marine sand into the entrance restricting water exchange between the estuary and the ocean this instantaneous reset of the system provided a unique opportunity to monitor and quantify generic inlet sedimentation processes and mechanisms an intensive data collection campaign was undertaken for one entire year following the clearance this dataset includes current and water level measurements calculation of the alongshore sediment supply and regular highly detailed morphological surveys of the infilling lagoon entrance system this contribution utilises this unique dataset to quantify the sediment ingress volumes rates and pathways within the accreting flood tide delta of the lagoon entrance it was found that ingress of sand into the system proceeds via a rapid landward infilling process as opposed to backfilling toward the ocean with the evolution of the flood tide delta occurring in distinct phases the location of the divergence point of the flood tidal current the amount of available accommodation space within the entrance system and the influence of storm events were found to be key factors in the evolving morphodynamics of this intermittently open closed coastal lagoon

high precision levelling dinsar and geomorphological effects in the emilia 2012 epicentral area abstract in may 2012 two moderate earthquakes mw 6 1 and 5 9 associated with a noticeable aftershock sequence affected the eastern sector of the po plain northern italy the co seismic areal uplift events are crucial for a better understanding of the seismotectonics of the broader area and thus for a better assessment of the seismic hazard in the region in the present study we compared the results of analyses based on high precision levelling the dinsar technique the distribution of liquefaction occurrences the geomorphological map of the area and the structural model of the region the dinsar technique revealed a marked uplift of the ground up to 17 cm which was confirmed by high precision levelling the results of both techniques substantially agreed although there were some considerable local discrepancies due to well documented and diffuse liquefaction phenomena some strategic precautions when planning high precision levelling networks are suggested

tsunami earthquakes slow thrust faulting events in the accretionary wedge the november 20 1960 peru october 20 1963 kurile and june 10 1975 kurile earthquakes are classified as tsunami earthquakes based on anomalously large tsunami excitation relative to earthquake magnitude long period surface wave analysis indicates double couple faulting mechanisms for all three events rather than single force mechanisms indicative of submarine landslides the earthquakes have shallow depths 15 km and are located near the trench axis and seaward of most other thrust zone events beneath the accretionary prism body waveform inversion indicates very shallowly dipping thrust faulting mechanisms for the three events with dip angles of 6 8 surface wave spectral amplitudes and deconvolution of sh waveforms suggests anomalously long source durations and large seismic moments relative to ms specifically the 1963 kurile event ms 7 2 shows a duration of 85 s and a moment of 6 0 1027 dyn cm mw 7 8 the 1975 kurile event ms 7 0 shows a duration of 60 s and a moment of 2 0 1027 dyn cm mw 7 5 and the 1960 peru event ms 6 75 shows a time function consisting of four subevents with a total duration of 110 130 s and a seismic moment of 3 4 1027 dyn cm mw 7 6 estimated rupture velocities are about 1 km s or less but there is no evidence of unusually low stress drops the august 1 1968 philippines event previously classified as a tsunami earthquake shows none of the anomalous source properties and teleseismic tsunami height measurements are sparse we do not consider this event a tsunami earthquake most of the anomalous tsunami excitation results from underestimation of earthquake size by ms due to the long source duration the tsunami heights are not significantly anomalous relative to seismic moment the slow nature of these events may result from rupture through the sedimentary rock along the basal decollement of the accretionary prism standard scaling laws when adjusted for the slow seismic velocity in the source region show an mw ms relationship similar to that observed for the tsunami earthquakes and predict ms saturation at about 7 3 rather than 8 0 for typical events

asperity distribution and earthquake occurrence in the southern kurile islands arc the seismicity in the southern kurile islands arc is characterized by a complex overlapping of aftershock zones of a few great and many large earthquakes ms 7 0 the spatial relationships of these aftershock zones can be explained in terms of a simple pattern of fault plane heterogeneity the four largest earthquakes in this region are from north to south the 1963 kurile islands mw 8 5 the 1958 etorofu mw 8 3 the 1969 kurile islands mw 8 2 and the 1973 nemuro oki mw 7 8 events detailed body wave studies indicate that the moment release associated with each event is concentrated in a small portion of the aftershock area with scale lengths 100 km these regions of high moment release are the largest asperities the areas that surround the large asperities slip in two modes 1 coseismically during the great events and 2 as distinct large ms 7 0 earthquakes both before and after the great events the second mode involves either rupture of relatively weak regions which results in low stress drop events or rupture of smaller asperities the earthquakes produced by failure of small asperities tend to repeatedly rupture the same regions and they have impulsive source time functions indicating rupture of highly stressed regions of the fault surface by analysis of all ms 7 0 events since 1946 in this region we find a segmentation of the southern kurile islands thrust zone into strongly coupled regions with two scale lengths dominant and secondary asperities and weakly coupled regions the surrounding areas generating the low stress drop events the largest earthquakes and the smaller asperity earthquakes occur at the down dip portion of the lithospheric interface while the low stress drop events occur much closer to the trench axis this implies a difference in the degree of mechanical coupling between the subducting and overriding plates with the deeper portions having greater strength than the shallower parts

hydro morphological modelling of small wave dominated estuaries small intermittently open or closed estuaries are characteristic of the coasts of south africa australia california mexico and many other areas of the world however modelling attention has tended to focus on big estuaries that drain large catchments and serve a wide diversity of interests e g agriculture urban settlement recreation commercial fishing in this study the development of a simple parametric system dynamics model to simulate the opening and closure of the mouths of small wave dominated estuaries is reported in the model the estuary is conceived as a basin with a specific water volume to water level relationship connected to the sea by a channel of fixed width but variable sill height changes in the form of the basin are not treated in the model while the dynamics of the mouth channel are central to the model the magnitude and direction of the flow through the mouth determines whether erosion or deposition of sediment occurs in the mouth channel influencing the sill height the model is implemented on the great brak estuary in south africa and simulations reveal that the raised low water levels in the estuary during spring tide relative to neap tide are occasioned by the constriction of the tidal flow through the shallow mouth freshwater inflows to the estuary are shown to be significant in determining the behaviour of the inlet mouth a factor often ignored in studies on tidal inlets further it is the balance between freshwater inflows and wave events that determines the opening or closure of the mouth of a particular estuary

modes of water renewal and flushing in a small intermittently closed estuary large water releases and mechanical breaching of the mouth can mimic major floods in flushing the waters of the estuary

stratigraphic evidence of a middle pleistocene climate driven flexural uplift in the alps 1 this interdisciplinary study on the subsurface stratigraphy of the po plain northern italy brings new evidence in support of a climate driven erosional unloading of the alps since the middle pleistocene a newly acquired high resolution seismic profile and a critical review of industrial seismic lines were integrated with sedimentologic observations on four magnetostratigraphically dated continental cores to reconstruct a three sequence evolution of the pleistocene clastic infill in the northern po basin during the first sequence ps1 1 4 0 87 ma characterized by sedimentation rates of 34 cm kyr outpacing regional subsidence meandering river systems prograded over the basin passing downstream to a cyclothemic shelfal succession the second sequence ps2 0 87 0 45 ma heralded by a regional unconformity r surface correlated to the onset of the major pleistocene glaciations was characterized by widespread continental sedimentation of generally distal braidplain the third sequence ps3 0 45 ma to present marked at the base by another regional unconformity y surface is characterized by proximal braided fluvial deposition under combined conditions of confinement erosion and bypass we interpret the ps3 sequence as deposited under the effects of a flexural uplift of the northern po plain during the middle pleistocene starting at 0 45 ma in response to the long term erosional unloading of the alps triggered by the waxing and waning of alpine glaciers since the late early pleistocene global cooling 0 9 ma according to our modeling erosion on a relatively limited area of the alpine mountain chain ranging from 1 3 to 1 7 mm yr in the axial sector to 0 1 0 3 mm yr at the margins has been able to trigger rock uplift over a wider area including the proximal peripheral basins

progressive offset and surface deformation along a seismogenic blind thrust in the po plain foredeep southern alps northern italy here we present for the first time in the po plain foredeep northern italy the middle to late pleistocene growth history of an outcropping secondary fold and related faults whose progressive deformation over an intermediate time window 105 years is driven by an underlying seismogenic blind thrust we trenched and logged an outcropping decametric secondary anticline related to a deeper blind compressional structure which deforms fluvial sediments and an overlying loess paleosol sequence folded units were dated using radiocarbon and optically stimulated luminescence methods to the late pleistocene holocene and tentatively correlated with glacial interglacial phases occurring during the time interval from marine isotope stage 6 to the present a multistep retrodeformation of the fold allowed us to calculate uplift rates for this secondary and shallow anticline varying between 0 02 and 0 1 mm yr since circa 200 kyr trishear forward deformation modeling of the fold indicates that the amplification of the observed fold could be caused by two shallow thrusts formed through a break backward activation this generated a decametric surface fold whose most recent growth was associated with bending moment normal faulting in the crestal and forelimb region our observations demonstrate that near surface compressive tectonics can be caused by blind thrusting via a complex array of fault and folds upward strain propagation and generation of shallow low angle thrust and related folding seem to be mainly due to secondary fold related faulting according to an out of syncline thrusting mechanism

maximal two layer exchange over a sill and through the combination of a sill and contraction with barotropic flow the analysis of two layer exchange flow through contractions with a barotropic component treated by armi farmer 1986 is extended to include exchange flows over sills and through a combination of a sill and contraction it is shown that exchange over a sill is fundamentally different from exchange through a contraction control at the sill crest acts primarily through the deeper layer into which the sill projects and only indirectly controls the surface layer this asymmetry in the control results in asymmetrical flows the interface depth above the crest is not one half the total depth as assumed in other studies by analogy with flow through contractions but is somewhat deeper the maximal exchange rate is less than for flow through a contraction of equal depth when both a sill and a contraction are present the contraction influences control at the sill crest only if it lies between the sill and the source of denser water the response to barotropic flow is also asymmetrical the transition to single layer flow occurs at much lower speeds for a barotropic component in one direction than the other results of the analysis are applied to exchange flow through the strait of gibraltar which includes both a sill and a contraction it is shown that maximal exchange conditions apply throughout part of the tidal cycle and observations illustrate several of the analytical predictions for barotropic flows including the formation of fronts single layer flow submaximal exchange and reverse flow

clay illuviation in red mediterranean soils abstract theories regarding pedogenesis in red mediterranean soils have undergone several stages of development the concept of clay illuviation in these soils was not a part of early theories and it is not yet unanimously accepted as a leading soil forming process a methodology is presented for studying the illuviation of clay in these soils emphasizing typology of textural features and fabrics the problem of age determination is also addressed through the use of radiometric dates and correlation with archaeological artifacts clay illuviation in red mediterranean soils under present day environmental conditions suggests that it occurs presently only on humid and sub humid margins of the mediterranean basin elsewhere illuvila clay accumulations are inherited from interglacial periods red mediterranean soils during glacial periods were eroded coluviated aggraded with aeolian dust calcitic fraction of which was redistributed in form of calcitic features and eventually were affected by water logging an example of water logging of red mediterranean soils mamora morocco which took place during the last glacial cycle consists of yellow illuvial clays accompanied by a yellowing of the ground mass during earlier cycles water logging resulted in whitish grey stains in which hydromorphic textural features were deposited

vegetation and fire history of the euganean hills colli euganei as recorded by lateglacial and holocene sedimentary series from lago della costa northeastern italy we reconstruct the vegetational and fire history of the colli euganei and northeastern po plain from c 16 500 cal bp to the present using ams dated sedimentary pollen microscopic and macroscopic charcoal records our study site lago della costa is the only natural water basin with an undisturbed late quaternary sediment accumulation in the northeastern po plain mixed coniferous deciduous forests occurred since at latest 14 500 cal bp gradual expansion of e g alnus glutinosa and carpinus betulus is documented after c 11 000 cal bp a further expansion of abies alba and alnus at 9200 cal bp coincided with a population buildup of these species in the insubrian region c 200 km northwest of our site a further increase of alnus about 6400 cal bp was accompanied by an expansion of castanea sativa and juglans regia as well as meadow and field plants this vegetational change was contemporaneous with a huge increase of regional and local fire activity our data suggest that fire disturbance favoure

mollusca stable isotope record of a core from lake frassino northern italy hydrological and climatic changes during the last 14 ka a core retrieved from lake frassino northern italy provided evidence of palaeohydrological change in this area during the last 14 ka lithological malacological and in particular stable isotope composition of freshwater shells allowed the delineation of the main phases of lake evolution between the lateglacial and holocene lateglacial conditions were drier than the holocene although a wetter period was inferred before c 14 ka according to the oxygen isotope composition of freshwater shells the holocene showed a clear bipartition the first part which lasted from 9100 to 7000 yr bp was drier and was followed by a rapid increase in humidity at 7000 6800 yr bp between 6800 and 5000 yr bp there were wetter and more stable conditions as indicated by smaller 18 o oscillations of pisidium and valvata shells from c 5000 to 2600 yr bp the record is characterized by larger fluctuations which may indicate that short term and particularly pronounced alternation of wet and dry periods occurred

the stratigraphic method in the study of large past earthquakes abstract the principles and development of the stratigraphic approach for identifying and studying traces of large old earthquakes are presented and discussed large earthquakes can be detected in quaternary sections predominantly for the late pleistocene and holocene in two ways firstly unusual deposits or facies may appear which are foreign to the long term depositional environment under study secondly fracture and or fold deformations bearing traces of impulsive instantaneous origin may be detected experience in this work involves two different categories with respect to tectonic and seismic activity areas in the tien shan and in the crimea the stratigraphic method opens new vistas in quaternary geology and paleoseismology

age soil forming processes and archaeology of the loess deposits at the apennine margin of the po plain northern italy new insights from the ghiardo area the significance of two loess profiles located in the ghiardo area reggio emilia northern italy along the southern margin of the po plain is discussed on the basis of sedimentary and pedological data optically stimulated luminescence osl dating and archaeological context loess sedimentation occurred during cold and arid glacial and stadial periods of the upper pleistocene between c 70 and 35 ka in the same time interval loess sedimentation occurred at other localities at the northern margin of the po plain po plain loess basin the early period of loess sedimentation was contemporary with an intense frequentation of the area by palaeolithic hunters whose remains consisting of clusters of flint artefacts are found at the base of the loess sequences thermoluminescence dates on burned flints are consistent with osl measurements on sediments where lithics were found and therefore the archaeological finds may be attributed to the middle palaeolithic lithic complexes of the mousterian culture subsequent soil forming processes on the loess deposits during the holocene are suggested by changes in the proprieties of the profiles clay illuviation hydromorphic and vertic features mukkara gilgai microrelief degradation processes of the topsoil leading to the formation of an eluvial top horizon were eventually triggered by deforestation which took place in the area since the chalcolithic period middle holocene

slip rates of blind thrusts in slow deforming areas examples from the po plain italy abstract we calculate plio pleistocene slip rates on the blind thrusts of the outer northern apennines fronts that are the potential sources of highly damaging earthquakes as shown by the m w 6 1 6 0 2012 emilia romagna seismic sequence slip rates are a key parameter for understanding the seismogenic potential of active fault systems and assessing the seismic hazard they pose however they are difficult to calculate in slow deforming areas like the po plain where faulting and folding is mostly blind to overcome this we developed a workflow which included the preparation of a homogeneous regional dataset of geological and geophysical subsurface information rich in plio pleistocene data we then constructed 3d geological models around selected individual structures to decompact the clastic units and restore the slip on the fault planes the back stripping of the differential compaction eliminates unwanted overestimation of the slip rates due to compaction induced differential subsidence finally to restore the displacement we used different methods according to the deformation style i e fault parallel flow for faulted horizons trishear and elastic dislocation modeling for fault propagation folds the result of our study is the compilation of a slip rate database integrating former published values with 28 new values covering a time interval from the pliocene to the present it contains data on 14 individual blind thrusts including the mirandola thrust seismogenic source of the 29 may 2012 m w 6 0 earthquake our study highlights that the investigated thrusts were active with rates ranging between 0 1 and 1 0 mm yr during the last 1 81 myr the mirandola thrust slipped at 0 86 0 38 mm yr during the last 0 4 myr these rates calculated with a homogeneous methodology through the entire po plain can be charged entirely to the thrust activity and not to secondary effects like the differential compaction of sediments across the structures

sedimentary and pedological processes in the upper pleistocene loess of northern italy the bagaggera sequence abstract the bagaggera sequence consists of two late pleistocene loesses superimposed on the top of middle pleistocene fluviatile sediments the lower loess includes at its base a mousterian archaeological level represented by artifacts dated by tl as 60 500 7500 bp and charcoal from hearths which mainly consists of boreal forest species at the top of the lower loess aurignacian artifacts occur which suggest a tentative date of 35 000 bp the sedimentary and pedological processes which lead to the formation of the sequence were reconstructed by means of mineral and textural analyses and thin section analysis and can be summarized as follows erosion and colluviation of the eemian soil at the base of the sequence during the early wurm isotopic substages 5 a c sedimentation of the lower loess deposits during the first pleniglacial period isotopic stage 4 a large number of coarse pedofeatures in this soil suggests that primary aeolian dust has been redistributed in place or for short distances by syngenetic slight pedogenesis and by water reworking as a result of alternating phases of wet and dry climate an alfisol characterized by strong clay illuviation developed in the lower loess during the hengelo arcy interstadial phase its top was affected by reworking and slight frost activity at the beginning of the second pleniglacial period isotopic stage 2 the upper loess was deposited in a drier environment during the second pleniglacial period isotopic stage 2 water reworking was less effective holocene weathering is expressed by clay illuviation and slight hydromorphism

a study of non linear tidal propagation in shallow inlet estuarine systems part i observations the offshore tide becomes strongly distorted as it propagates into shallow estuarine systems observations of sea surface elevation and horizontal currents over periods ranging from three days to one year at nine stations within nauset inlet estuary document the non linear interaction of the off shore equilibrium tidal constituents despite strong frictional attenuation within the estuary the overtides and compound tides of m2 s2 and n2 in particular reach significant amplitude resulting in strong tidal distortion high frequency forced constituents in sea surface are phase locked consistently leading the forcing tides by 60 70 resulting in a persistent distortion where falling tide is longer than rising tide forced constituents in currents are more nearly in phase with equilibrium constituents producing flood currents which are shorter but more intense than ebb currents a compound fortnightly tide msf modulates the mean water level such that lowest tides occur during neap phase instead of spring phase this fortnightly tide can be contaminated by storm surge changing the phase characteristics of this constituent implications of the overtides compound tides and lower frequency tides on near bed suspended and dissolved material transport are profound

comparison of earthquake scaling relations derived from data of the instrumental and preinstrumental era estimates of surface rupture displacement and magnitude for crustal earthquakes from the preinstrumental era pre 1900 tend to be greater than the corresponding estimates derived from modern scaling relations we investigate this tendency using an expanded and updated version of the earthquake dataset of wells and coppersmith 1994 to fit regression relations of moment magnitude on surface rupture length and rupture area and average surface displacement on surface rupture length separate relations are fitted to preinstrumental and instrumental data and the results compared to the equivalent relations of wells and coppersmith we find that our relations for instrumental data remove some but not all of the differences between the preinstrumental data and the relations of wells and coppersmith we attribute the remaining differences largely to natural censoring of surface displacements less than about 1 m and surface rupture lengths less than about 5 km from the dataset for the preinstrumental era because regressions constructed from similarly censored instrumental data are indistinguishable from the preinstrumental regressions since the regressions for our censored instrumental data i e restricted to moderate to large earthquakes are different from regressions for our complete dataset of instrumental earthquakes and from the regressions of wells and coppersmith both with a larger proportion of small to moderate earthquakes the results may indicate that large earthquakes have different scaling relationships from those of smaller earthquakes

a major seismogenic fault in a silent area the castrovillari fault southern apennines italy summary large historical earthquakes in italy define a prominent gap in the pollino region of the southern apennines geomorphic and palaeoseismological investigations in this region show that the castrovillari fault cf is a major seismogenic source that could potentially fill the southern part of this gap the surface expression of the cf is a complex 10 13 km long set of prominent scarps trenches across one scarp indicate that at least four surface faulting earthquakes have occurred along the cf since late pleistocene time each producing at least 1 m of vertical displacement the length of the fault and the slip per event suggest m 6 5 7 0 for the palaeoearthquakes preliminary radiocarbon dating coupled with historical considerations imply that the most recent of these earthquakes occurred between 380 bc and 1200 ad and probably soon after 760 ad no evidence for this event has been found in the historical record we estimate a minimum recurrence interval of 1170 years and a vertical slip rate of 0 2 0 5 mm yr for the cf which indicates that the seismic behaviour of this fault is comparable to other major seismogenic faults of the central southern apennines the lack of mention or the mislocation of the most recent event in the historical seismic memory of the pollino region clearly shows that even in italy which has one of the longest historical records of seismicity a seismic hazard assessment based solely on the historical record may not be completely reliable and shows that geological investigations are critical for filling possible information gaps

soil evolution and origin of landscape in a late quaternary tectonically mobile setting the po plain northern apennines border in lombardy italy abstract the interactions among quaternary paleo soil forming erosion re deposition and geomorphic processes at the origin of the present day landscape are discussed at three isolated tectonic reliefs of the southern po foredeep basin of lombardy san colombano casalpusterlengo and zorlesco reliefs italy these sites offer the possibility to combine different scales of geopedological geomorphological stratigraphic and structural observations to unravel the contribution of climate and tectonics to the quaternary geological evolution and to the origin of the landscape field surveys laboratory analyses and soil micromorphology were used to characterize the late quaternary pedogenic processes acting on different paleo surfaces in combination with the detailed study of seven selected soil profiles pedo stratigraphic correlations revealed that two alluvial loess paleosol sequences which originated from the late pleistocene to holocene glacial interglacial fluctuations are differently preserved throughout the present day hill landscape in situ paleosols allowed to localize the paleo topographic surfaces of geomorphic tectonic and sedimentary stabilization redeposited paleosols occurring systematically close to the main faults and or at the erosional bottom of paleo valleys allowed to mark the stages of tectonic instability the integrated approach contributed to unravel the composite nature and rank of the stratigraphic boundaries polycyclic loess soil aggradation characterized the stable paleo highs uplifted during different phases of active thrusting of the northernmost emilian arcs of the apennine while valley incision fluvial terracing soil truncation and redeposition occurred in the intervening structural lows in the san colombano hill area late pleistocene transtensional faulting induced changes of the drainage network and enhanced redeposition of paleosols in colluvial wedges on the hangingwalls along the fault scarps lgm loess was preserved above different dissected remnants of the paleo topography composing the hilltops these new constraints permit to refine the late quaternary tectono depositional history and landscape evolution at the southern margin of the po basin

pliocene quaternary sedimentation in the northern apennine foredeep and related denudation the deposits of the pliocene quaternary foredeep of the northern apennine cover at present an area of 103000 km2 the original boundaries of the basin are not known since marginal deposits have been eroded in particular those of the inner southwestern border during pliocene times the basin area was reduced by thrust tectonics and the amount of shortening may be tentatively estimated the present volume of pliocene and quaternary sediments may be inferred with good approximation from the maps of the base of the pliocene and of the quaternary base of the hyalinea balthica zone successions the pliocene volume has been corrected adding the estimate of the underthrust sediments while no correction has been attempted for the eroded marginal deposits the estimates of 97000 and 95000km3 reflecting the present volume of the pliocene and quaternary deposits are therefore significantly less than the volumes originally deposited present volumes have been transformed in net 0 porosity volumes in order to obtain the relative net supply rates 0 021 pliocene and 0 047 quaternary km3 a other unmeasurable factors volume variations due to the weathering of silicates loss of leached carbonates may induce a probably unimportant underestimate of the supply rates available data allow an approximate estimate of the range of the net volume of the holocene sediments deposited during the last 6000 a bp 221 276km3 and of the relative net supply rate 0 037 0 046km3 a that is not significantly different from the quaternary one applying a porosity correction these supply rates may be related to the quaternary source area 128000km2 to obtain the relative denudation rates 0 41 0 46mm a quaternary and 0 36 0 51 mm a holocene present supply and denudation rates deduced from the direct measurements of the bed load and suspended load of the apenninic and alpine rivers do not differ significantly from the quaternary and holocene ones available data do not allow a reliable estimate of the pliocene source area and consequently of the pliocene denudation rate however a minimum of 160000 177 000 km3 has been eroded during pliocene and quaternary times assuming as a working hypothesis that the pliocene source area did not significantly differ from the present one an average thickness of 1240 1390 m could have been eroded since the beginning of pliocene this estimate is in agreement with the values obtained from the measurements of coalification of vegetal organic matter in the outcrops and suggests that post orogenic successions and higher thrust sheets may have been completely removed in vast areas