sea ice motion in response to geostrophic winds it is an old rule of thumb that sea ice moves with a speed of about 2 of the surface wind and about 45 to the right of the wind a similar relationship between the ice velocity and the geostrophic wind is examined here it is found that only about half of the long term several month average ice motion is directly related to the geostrophic wind the other half being due to the mean ocean circulation on shorter time scales and in all seasons more than 70 of the variance of the ice velocity in the central arctic ocean is explained by the geostrophic wind within about 400 km of the coasts the geostrophic wind is less successful in explaining the ice motion the spatial variations in ice velocity are also partly explained by the geostrophic wind about half of the variance in the large scale ice vorticity and shear are accounted for on the other hand none of the large scale ice divergence can be explained by the wind the long term average ocean current is estimated by subtracting the share of the ice motion caused by the wind from the total ice motion

shallow seismic source parameter determination using intermediate period surface wave amplitude spectra summary estimating reliable depths for shallow seismic sources is important in both seismo tectonic studies and in seismic discrimination studies surface wave excitation is sensitive to source depth especially at intermediate and short periods owing to the approximate exponential decay of surface wave displacements with depth a new method is presented here to retrieve earthquake source parameters from regional and teleseismic intermediate period 100 15s fundamental mode surface wave recordings this method makes use of advances in mapping globaldispersiontoallowhigherfrequencysurfacewaverecordingsatregionalandteleseismic distances to be used with more confidence than in previous studies and hence improve the resolution of depth estimates synthetic amplitude spectra are generated using surface wave theory combined with a great circle path approximation and a grid of double couple sources are compared with the data source parameters producing the best fitting amplitude spectra are identified by minimizing the least squares misfit in logarithmic amplitude space the f test is used to search the solution space for statistically acceptable parameters and the ranges of these variables are used to place constraints on the best fitting source estimates of focal mechanism depth and scalar seismic moment are determined for 20 small to moderate sized 4 3 mw 6 4 earthquakes these earthquakes are situated across a wide range of geographic and tectonic locations and describe a range of faulting styles over the depth range 4 29km for the larger earthquakes comparisons with other studies are favourable however existing source determination procedures such as the cmt technique cannot be performed for the smaller events by reducing the magnitude threshold at which robust source parameters can be determined the accuracy especially at shallow depths of seismo tectonic studies seismic hazard assessments and seismic discrimination investigations can be improved by the application of this methodology

spatial variation in stresses in peninsular italy and sicily from background seismicity abstract we have retrieved the stress tensor orientation in the italian region applying the fmsi technique gephart j 1990b fmsi a fortran program for inverting fault slickenside and earthquake focal mechanism data to obtain the regional stress tensor comput geosci 16 953 989 to fault plane solutions of 298 small earthquakes 2 5 m d istituto nazionale di geofisica in the period 1988 1995 first we verified that the stress inversion procedure generally applied to a large number of focal mechanisms of earthquakes recorded in a local seismic network could be successfully used in italy using background seismicity recorded over large 100 200 km regions then comparing the stress inversion results with other stress indicators we find that they are geologically sound for many regions in italy even if the misfit values are relatively large we also find that the largest misfit values are determined by a few earthquakes only 10 20 of the total number excluding these earthquakes from inversion the average misfit becomes much lower by 30 40 the results obtained in this study confirm the large variations of the stress field over a relatively short distance in italy but also confirm the existence of regions extending for a few hundred kilometres within which the stress is homogeneous among these most of the apennines are dominated by extension perpendicular to the trend of the mountain belt only in the northern apennines is there any clear distinction between an area of extension in the inner portion of the belt and an area under horizontal compression along the adriatic margin of the belt more rapid variations occur around calabria and sicily as expected because of the complexities linked with the tyrrhenian subduction and with active volcanism in the ionian calabrian coastal region there are hints of active nw se compression although constrained by a few data whereas in the messina strait we observe e w extension and a vertical 1 in northern and western sicily our results indicate n s to nw se compression roughly consistent with the general convergence between the european and the african plates

waveform modeling of historical seismograms of the 1930 irpinia earthquake provides insight on blind faulting in southern apennines italy 1 the southern apennines chain is related to the west dipping subduction of the apulian lithosphere the strongest seismic events mostly occurred in correspondence of the chain axis along normal nw se striking faults parallel to the chain axis these structures are related to mantle wedge upwelling beneath the chain in the foreland faulting develops along e w strike slip to oblique slip faults related to the roll back of the foreland similarly to other historical events in southern apennines the i0 xi mcs intensity scale 23 july 1930 earthquake occurred between the chain axis and the thrust front without surface faulting this event produced more than 1400 casualties and extensive damage elongated approximately e w the analysis of the historical waveforms provides the chance to study the fault geometry of this anomalous event and allow us to clarify its geodynamic significance our results indicate that the ms 6 6 1930 event nucleated at 14 6 3 06 km depth and ruptured a north dipping n100 e striking plane with an oblique motion the fault propagated along the fault strike 32 km to the east at about 2 km s the eastern fault tip is located in proximity of the vulture volcano the 1930 hypocenter similarly to the 1990 mw 5 8 southern apennines event is within the mesozoic carbonates of the apulian foredeep and the rupture developed along a blind fault the 1930 fault kinematics significantly differs from that typical of large southern apennines earthquakes which occur in a distinct seismotectonic domain on late pleistocene to holocene outcropping faults these results stress the role played by pre existing blind faults in the apennines subduction setting

formation and preservation of pedogenic carbonates in south india links with paleo monsoon and pedological conditions clues from sr isotopes u th series and rees the influence of the pedogenic and climatic contexts on the formation and preservation of pedogenic carbonates in a climosequence in the western ghats karnataka plateau south west india has been studied along the climosequence the current mean annual rainfall mar varies within a 80 km transect from 6000 mm at the edge of the plateau to 500 mm inland pedogenic carbonates occur in the mar range of 500 1200 mm in the semi arid zone mar 500 900 mm carbonates occur i as rhick hardpan calcretes on pediment slopes and ii as nodular horizons in polygenic black soils i e vertisols in the sub humid zone mar 900 1500 mm pedogenic carbonates are disseminated in the black soil matrices either as loose irregular and friable nodules of millimetric size or as indurated botryoidal nodules of centimetric to pluricentimetric size they also occur at the top layers of the saprolite either as disseminated pluricentimetric indurated nodules or carbonate cemented lumps of centimetric to decimetric size chemical and isotopic sr 87 sr 86 compositions of the carbonate fraction were determined after leaching with 0 25 n hcl the corresponding residual fractions containing both primary minerals and authigenic clays were digested separately and analyzed the trend defined by the sr 87 sr 86 signatures of both labile carbonate fractions and corresponding residual fractions indicates that a part of the labile carbonate fraction is genetically linked to the local soil composition considering the residual fraction of each sample as the most likely lithogenic source of ca in carbonates it is estimated that from 24 to 82 55 on average of ca is derived from local bedrock weathering leading to a consumption of an equivalent proportion of atmospheric co2 these values indicate that climatic conditions were humid enough to allow silicate weathering mar at the time of carbonate formation likely ranged from 400 to 700 mm which is 2 to 3 fold less than the current mar at these locations the sr u and mg contents and the u 234 u 238 activity ratio in the labile carbonate fraction help to understand the conditions of carbonate formation the relatively high concentrations of sr u and mg in black soil carbonates may indicate fast growth and accumulation compared to carbonates in saprolite possibly due to a better confinement of the pore waters which is supported by their high u 234 u 238 signatures and or to higher content of dissolved carbonates in the pore waters the occurrence of ce mn and fe oxides in the cracks of carbonate reflects the existence of relatively humid periods after carbonate formation the carbonate ages determined by the u th method range from 1 33 0 84 kyr to 7 5 2 7 kyr and to a cluster of five ages around 20 kyr i e the last glacial maximum period the young occurrences are only located in the black soils which therefore constitute sensitive environments for trapping and retaining atmospheric co2 even on short time scales the maximum age of carbonates depends on their location in the climatic gradient from about 20 kyr for centimetric nodules at mule hole mar 1100 mm yr to 200 kyr for the calcrete at gundlupet mar 700 mm yr durand et al 2007 the intensity of rainfall during wet periods would indeed control the lifetime of pedogenic carbonates and thus the duration of inorganic carbon storage in soils c 2010 elsevier ltd all rights reserved

seismic moment tensors of the april 2009 l aquila central italy earthquake sequence summary on 2009 april 6 the central apennines were hit by an mw 6 3 earthquake the region had been shaken since 2008 october by seismic activity that culminated in two foreshocks with mw 4 1 week and a few hours before the main shock we computed seismic moment tensors for 26 events with mw between 3 9 and 6 3 using the regional centroid moment tensor rcmt scheme most of these source parameters have been computed within 1 hr after the earthquake and rapidly revised successively the focal mechanisms are all extensional with a variable and sometimes significant strike slip component this geometry agrees with the ne sw extensional deformation of the apennines known from previous seismic and geodetic observations events group into three clusters those located in the southern area have larger centroid depths and a wider distribution of t axis directions these differences suggest that towards south a different fault system was activated with respect to the sw dipping normal faults beneath l aquila and more to the north

seismic remote sensing for the earthquake source process and near source strong shaking a case study of the october 16 1999 hector mine earthquake a new methodology to automatically determine the earthquake source process and near source strong ground motions using regional and local distance data was used to study the october 16 1999 hector mine earthquake mw7 1 broadband displacement data were inverted for the seismic moment tensor and to resolve the fault plane ambiguity independent of aftershock location and surface faulting information the identified nnw striking fault plane was used to invert for the distribution of fault slip over a planar surface the slip model was used to predict near fault peak ground velocity which was found to agree well with the trinet shakemap and also with near fault observations that were not available at the time of the initial analysis our method if automated is capable of providing near source strong ground motion information within 30 minutes of the earthquake origin time even in cases where there are few near fault recording instruments

carbonate accumulation and weathering of the granitic substratum of tanecherfi basin northeastern morocco abstract in the tanecherfi basin a granitic body is partly overlain by a calcrete which only seems superimposed morphologically the profiles consist of three horizons the lowest one corresponds to a filling of carbonates into the weathered granitic rocks microscopically the carbonates cut the primary minerals along open cracks and voids in the second horizon the increased carbonation results in calcite septa that gradually isolate rock cells inclosed in a micritic matrix forming a cortex gradually the rock residues vanish and glaebules appear the upper horizon is characterized by a micritic matrix associated with the disappearance of the nodules these morphologic relations are confirmed by chemical data the primary minerals are weathered silica is locally released and precipitates partly around the glaebules magnesium combines into the carbonate structure but locally combines with the silica of the cortex of the glaebules aluminium seems to be totally removed the granite calcrete relationships indicate a weathering process rather to a simple superposition

nied seismic moment tensor catalogue for regional earthquakes around japan quality test and application abstract we have examined the quality of the national research institute for earth science and disaster prevention nied seismic moment tensor mt catalogue obtained using a regional broadband seismic network freesia first we examined using synthetic waveforms the robustness of the solutions with regard to data noise as well as to errors in the velocity structure and focal location then to estimate the reliability robustness and validity of the catalogue we compared it with the harvard centroid moment tensor cmt catalogue as well as the japan meteorological agency jma focal mechanism catalogue we found out that the nied catalogue is consistent with harvard and jma catalogues within the uncertainty of 0 1 in moment magnitude 10 km in depth and 15 in direction of the stress axes the nied mt catalogue succeeded in reducing to 3 5 the lower limit of moment magnitude above which the moment tensor could be reliably estimated finally we estimated the stress tensors in several different regions by using the nied mt catalogue this enables us to elucidate the stress deformation field in and around the japanese islands to understand the mode of deformation and applied stress moreover we identified a region of abnormal stress in a swarm area from stress tensor estimates

seismic evidence of longitudinal extension in the southern apennines chain italy the 1997 1998 sannio matese seismic sequence 1 we present evidence of longitudinal extension in the apennines based on data from the 1997 1998 sannio matese seismic sequence the earthquakes occurred between the nw se faults responsible for larger historical earthquakes inversion of focal mechanisms indicates a stress field with a prevailing normal stress characterized by a nnw sse sub horizontal 3 this stress regime is consistent with normal movements along ne sw faults these features suggest that the ne sw faults located in between the nw se faults cannot be interpreted as transfer faults or old faults reactivated during the eastward migration of the chain we propose that the deformation due to the eastward chain migration concentrates along nw se normal faults which are responsible for the largest earthquakes whereas the deformation related to the chain curvature concentrates along ne sw normal faults which are responsible for the lower energy seismic sequences

strontium and carbon isotope tracers and the origins of soil carbonate in south australia and victoria abstract calcium carbonate occurs in soils in association with a variety of rock types in coastal and inland south australia and victoria the 87 sr 86 sr ratios of the coastal soil carbonates fall between 0 7094 and 0 7098 showing that the ocean is the principal source of calcium to nearly all soils near the coast and that contributions from bedrock are generally small an exception is the soil formed on the young volcano at mt gambier in which the average ratio for carbonate is about 0 7070 compared to 0 7041 for the volcanic ash the basaltic ash of the volcano is readily weathered and rich in calcium roughly 40 of strontium and 10 to 20 of the calcium in the soil carbonate derives from the ash and the balance from marine sources the 87 sr 86 sr ratios from soil carbonate gradually increase inland reaching values of 0 7152 these higher ratios reflect at least in part the increasing 87 sr 86 sr ratio of inland dust in contrast the ocean does not contribute significantly to the carbon pool of the soils we studied the 13 c pdb values of soil carbonates on kangaroo island and the higher rainfall areas of eastern victoria fall between 11 0 and 8 7 indicating that the carbonate formed in equilibrium with the c3 dominated vegetation typical of the region in the warmer inland areas to the north such as the eyre peninsula the 13 c value of soil carbonate averages 5 3 reflecting the higher proportion of c4 plants in the local biomass mixing with marine sources of carbonate cannot account for the observed carbon isotopic patterns the flux of carbon into soils from the ocean therefore must be small compared to that derived from plant respiration and decay

european mediterranean regional centroid moment tensors 1997 2000 the mediterranean region is seismically very active and undergoing rapid deformation earthquakes as strong as m 6 are present but relatively rare on the other hand moderate magnitude seismicity 4 5 m 5 5 is widespread and often damaging an improved knowedge of moderate magnitude earthquakes can contribute significantly to a better understanding of active tectonics in the region harvard centroid moment tensors cmt today represent the most widely used reference for reliable source mechanisms but modelling seismic sources with the cmt technique for earthquakes with magnitude less than m 5 5 5 is quite difficult since 1997 we are using an extension of the standard cmt algorithm to compute regional centroid moment tensors rcmt for moderate magnitude earthquakes mw as low as 4 0 analyzing intermediate period surface waves from regional and teleseismic seismograms we routinely apply the algorithm to european mediterranean seismicity to produce a catalog of seismic moment tensors for events with magnitude between 4 5 and 5 5 which generally are not included in the harvard cmt catalog in this paper we show the results for earthquakes that occurred between 1997 and 2000 consisting of 252 solutions and we discuss the characteristics of the catalog and the areas where these new data are most relevant

present day stress field modelling of southern italy constrained by stress and gps data abstract the present day tectonic setting of the italian peninsula is very complex and involves competing geodynamic processes in this context southern peninsular italy is characterised by extension along the apenninic belt and in the tyrrhenian margin and by transpression in the apulia gargano region the extension is well defined by means of geological seismological and contemporary stress data for the latter only few data are available in the apulia gargano region leaving the state of stress in that area unresolved here we develop a finite element model of the southern italian region in order to predict the contemporary stress field our model predictions are constrained by model independent observations of the orientation of maximum horizontal stress s hmax the tectonic regime and the horizontal velocities derived from gps observations we performed a blind test with 31 newly acquired s h max orientations in the southern apennines these new data come from the analysis of orehole breakouts performed in 46 deep oil exploration wells ranging in depth from 1300 to 5500 m the model results agree with the stress data that define a prevailing nw se s h max orientation along the apenninic belt and foredeep and thus are capable to predict the stress field where no stress information is available we first analyse how much model predictions based on older data deviate from present day stress data and then recalibrate the models based on our new stress data giving insight into the resolution of both models and data in the studied region which is affected by low deformation rates we find that geodetic data alone cannot resolve such low levels of deformation due to the high relative measurement errors we conclude that both gps and stress data are required to constrain model results

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

active stress map of italy we present a new map of the present day stress field in italy obtained from all the available data the map reports 200 horizontal stress directions inferred from 109 borehole breakout data 44 centroid moment tensor solutions 34 other focal mechanisms most of which are from polarity distributions seven stress inversions of microearthquake data two averages of t and p axes of earthquake focal mechanisms in zones of diffuse seismic activity and four fault slip data the integration of breakout data which yield horizontal stress directions with fault plane solutions which reflect the stress regime allows us to obtain an improved map of the present day stress in italy this stress field map can be used for a better comprehension of active tectonic processes for seismic hazard assessment and to foresee the behavior of faults recognized with other methods stress directions obtained from different data although relative to different depth intervals e g 0 7 km for breakouts and 0 20 km for most of the earthquakes and to different tectonic units are consistent since many regions in italy are characterized by an extensional stress regime we report the minimum horizontal stress shmin orientations the map shows that an extensional regime affects most of the apenninic belt conversely a compressional or transpressional regime characterizes the eastern alps the eastern side of the northern apennines and the southern tyrrhenian to northern sicily zone an abrupt change in stress directions marks the transition between northern and southern apennines suggesting that the two arcs are characterized by a different tectonic setting and recent evolution in this paper we report all the data analyzed to date with their geographic coordinates and average stress directions and we describe the main stress provinces in italy in the framework of the tectonic evolution of the region

sea ice motion from satellite passive microwave imagery assessed with ers sar and buoy motions observing the motion of sea ice from space is analogous to observing wind stress over the wet oceans both provide surface forcing for modeling ocean dynamics ice motion also directly provides the advective component of the equations governing the mass balance of the sea ice cover thus its routine observation from space would be of great value to understanding ice and ocean behavior to demonstrate the feasibility of creating a global multidecadal ice motion record from satellite passive microwave imagery and to quantitatively assess the errors in the estimated ice motions we have tracked ice every 3 days in the arctic ocean and daily in the fram strait and baffin bay during the 8 winter months from october 1992 to may 1993 and daily in the weddell sea during the 8 winter months from march to october 1992 the method which has been well used previously involves finding the spatial offset that maximizes the cross correlation of the brightness temperature fields over 100 km patches in two images separated in time by from 1 to 3 days the resulting ice motions are compared with contemporaneous buoyand sar derived ice motions the uncertainties in the displacement vectors between 5 and 12 km are better than the spatial resolution of the data both 85 ghz data with 12 km spatial resolution and 37 ghz data with 25 km resolution are tracked these trials with the 37 ghz data are new and show quite surprisingly that the error is only about 1 km larger with these data than with the 12 km 85 ghz data errors are typically larger than average in areas of lower ice concentration in the most dynamic regions particularly near the ice edge in the barents and greenland seas and in zones of high shear these passive microwave ice motions show a large increase in spatial detail over motion fields optimally interpolated from buoy and wind observations especially where buoy data are virtually absent such as near coasts and in some passages between the arctic ocean and its peripheral seas the feasibility of obtaining ice motion from the 37 ghz data in addition to the 85 ghz data should allow an important record of ice motion to be established for the duration of the scanning multichannel microwave radiometer smmr special sensor microwave imager ssm i and future microwave sensors that is from 1978 into the next millenium

a new light on arresting mechanism of dynamic earthquake faulting classic analyses have shown that dynamic growth of a shear crack cannot be arrested in a uniformly stressed elastic medium with homogeneously distributed fracture strengths this leads to a general supposition that earthquake rupture growth is arrested by inhomogeneities in the distributions of strengths or stresses we propose a novel idea for arresting mechanism of dynamic crack growth in the simulation with no constraints on the crack geometry our analysis shows that the arresting occurs spontaneously soon after crack bending even in the homogeneous medium and that inhomogeneities are indispensable not for stopping crack growth but for its promotion

tectonics of the mattinata fault offshore south gargano southern adriatic sea italy implications for active deformation and seismotectonics in the foreland of the southern apennines the mattinata fault is an e w trending feature 50 km long that cuts across the gargano promontory in the foreland of the southern apennines most researchers agree that it is a strike slip fault although the timing of activity is not well known mainly because of the scarce occurrence of cenozoic sediments this contribution aims to describe the eastward extent of the mattinata fault in the adriatic sea using a grid of multichannel seismic profiles specifically acquired for this study and taking advantage of the occurrence of offshore oligocene to quaternary sediments to help date the deformation results indicate that from the late miocene to the quaternary compression dominated and only a limited component of strike slip occurred along the fault a strike slip tectonic regime on the other hand was likely dominant during the late cretaceous to paleogene seismicity affects gargano at basement depth and extends northward into the central adriatic suggesting that the offshore extent of the mattinata fault may not currently represent the main site of foreland deformation within the adriatic region although the mattinata fault probably originated as a crustal scale strike slip fault it has been subsequently reactivated in different tectonic regimes the strike slip ml 5 4 2002 san giuliano molise earthquake located 70 km west of the mattinata fault outcrop seems to have been related to the reactivation of a set of preexisting foreland faults and it does not characterize the seismotectonics of the entire mattinata fault our reconstruction has wide implications not only for a better understanding of the tertiary evolution and active tectonics of the adriatic foreland but also for general relationships among preexisting structures foreland tectonics and seismotectonics

co seismic displacements associated to the molise southern italy earthquake sequence of october november 2002 inferred from gps measurements abstract the 2002 earthquake sequence of october 31 and november 1 main shocks mw 5 7 struck an area of the molise region in southern italy in this paper we analyzed the co seismic deformation related to the molise seismic sequence inferred from gps data collected before and after the earthquake that ruptured a rather deep portion of crust releasing a moderate amount of seismic energy with no surface rupture the gps data have been reduced using two different processing strategies and softwares bernese and gipsy to have an increased control over the result accuracy since the expected surface displacements induced by the molise earthquake are in the order of the gps reliability the surface deformations obtained from the two approaches are statistically equivalent and show a displacement field consistent with the expected deformation mechanism and with no rupture at the surface in order to relate this observation with the seismic source an elastic modeling of fault dislocation rupture has been performed using seismological parameters as constraints to the model input and comparing calculated surface displacements with the observed ones the sum of the seismic moments 8 9 1017 nm of the two main events have been used as a constraint for the size and amount of slip on the model fault while its geometry has been constrained using the focal mechanisms and aftershocks locations since the two main shocks exhibit the same fault parameters strike of the plane dip and co seismic slip we modelled a single square fault size of 15 km 15 km assumed to accommodate the whole rupture of both events of the seismic sequence a vertical e w trending fault strike 266 has been modeled with a horizontal slip of 120 mm sensitivity tests have been performed to infer the slip distribution at depth the comparison between gps observations and displacement vectors predicted by the dislocation model is consistent with a source fault placed between 5 and 20 km of depth with a constant pure right lateral strike slip in agreement with fault slip distribution analyses using seismological information the gps strain field obtained doesn t require a geodetic moment release larger than the one inferred from the seismological information ruling out significant post seismic deformation or geodetic deformation released at frequencies not detectable by seismic instruments the molise sequence has a critical seismotectonic significance because it occurred in an area where no historical seismicity or seismogenic faults are reported the focal location of the sequence and the strike slip kinematics of main shocks allow to distinguish it from the shallower and extensional seismicity of the southern apennines being more likely related to the decoupling of the southern adriatic block from the northern one

the 2002 molise earthquake sequence what can we learn about the tectonics of southern italy abstract on october 31 2002 a m l 5 4 earthquake occurred in southern italy at the margin between the apenninic thrust belt to the west and the adriatic plate to the east in this area neither historical event nor seismogenic fault is reported in the literature in spite of its moderate magnitude the earthquake caused severe damage in cities close to the epicenter and 27 people out of a total of 29 casualties were killed by the collapse of a primary school in s giuliano di puglia by inverting broadband regional waveforms we computed moment tensor solutions for 15 events as small as m l 3 5 m w 3 7 the obtained focal mechanisms show pure strike slip geometry mainly with focal planes oriented to ns sinistral and ew dextral in several solutions focal planes are rotated counterclockwise in particular for later events occurring west of the mainshock from the relocated aftershock distribution we found that the mainshock ruptured along an ew plane and the fault mechanisms of some aftershocks were not consistent with the mainshock fault plane the observed stress field resulting from the stress tensor inversion shows a maximum principal stress axis with an east west trend n83 w whereas the minimum stress direction is almost n s considering both the aftershock distribution and moment tensor solutions it appears that several pre existing faults were activated rather than a single planar fault associated with the mainshock the finite fault analysis shows a very simple slip distribution with a slow rupture velocity of 1 1 km s that could explain the occurrence of a second mainshock about 30 h after finally we attempt to interpret how the molise sequence is related to the normal faulting system to the west along the apennines and the dextral strike slip mattinata fault to the east

crustal structure in the area of the 2002 molise earthquake clues for the evolution of the southern apennines the apennines is a mountain belt with paired extension and compression that are explained by the subduction and delamination of the ionian adria lithosphere during the belt formation the adria crust is flexed downward and then incorporated into the wedge after peeling off along some weak level whose origin is still discussed in southern apennines this process seems to have stopped at about 0 7 ma by the development of a tear in the subducting lithosphere and consequent extension that spread along the mountain range seismological data acquired after the 2002 mw 6 0 molise strike slip earthquake yield modeling the structure of the adria crust as congealed close to the leading edge of the belt tomography images show inverted normal faults within the sedimentary cover apulian units fault inversion incomplete close to the compressional front testifies for a final squeezing of the entire previously flexed apulian continental margin pronounced high vp and low vp vs anomalies are observed at depth greater than 12 km and undoubtfully attributed to heterogeneities of the basement solving the long lasting contention on the nature of similar high speed bodies observed beneath the apennines beneath these bodies we observe a strong reflectivity suggesting the presence of a fluid filled layer in the middle lower crust that may act as a decoupling level in the apennines tectonics the deep fluids are also favoring the rupture of strike slip earthquakes like those that occurred in 2002 and the intermediate depth seismicity diffused in the apulian region

seismic sequences and swarms in the latium abruzzo molise apennines central italy new observations and analysis from a dense monitoring of the recent activity abstract we present a detailed analysis of the seismic activity in the central apennines based on a high quality seismogram data set collected from two temporary and three permanent networks this integrated network recorded between january 2009 and december 2013 a total of 7011 local earthquakes 6270 selected for this study with local magnitudes m l ranging from 0 4 to 4 7 hypocentres were located by using a reference 1d crustal velocity model determined with a genetic algorithm the majority of the hypocenters are located beneath the axis of the apenninic belt while the rest are found along the peri tyrrhenian margin hypocentral depth distribution extends to a depth of 31 km with a pronounced peak between 8 and 12 km both low to moderate magnitude seismic sequences and diffuse swarm like seismicity was observed there were two major seismic swarms and a seismic sequence which included the marsica sora m l 4 7 main shock a total of 468 fault plane solutions were derived from p wave polarities this new data set more than quadruples the number of focal mechanisms that was previously available for regional stress field analysis in the study region the majority of the fault plane solutions in the central apennines show predominantly normal fault movements with t axis trends oriented ne sw focal mechanisms calculated in this study confirm that this area is in extension for the seismic swarms sequence in the marsica sora area we also derived the azimuth and plunge of the principal stress axes by inverting fault plane solutions we find a few right lateral strike slip focal mechanisms that possibly identify the prolongation of the strike slip kinematics in the gargano apulia foreland to the west and mark the passage to the nw se striking normal faults of the inner apenninic belt the seismicity and stress distribution we observe might be consistent with a fragmented tectonic scenario in which faults with small dimensions release seismic energy in a diffused way

seismotectonics of strike slip earthquakes within the deep crust of southern italy geometry kinematics stress field and crustal rheology of the potenza 1990 1991 seismic sequences mmax 5 7 abstract we present a revision and a seismotectonic interpretation of deep crust strike slip earthquake sequences that occurred in 1990 1991 in the southern apennines potenza area the revision is motivated by i the striking similarity to a seismic sequence that occurred in 2002 140 km nnw in an analogous tectonic context molise area suggesting a common seismotectonic environment of regional importance ii the close proximity of such deep strike slip seismicity with shallow extensional seismicity apennine area and iii the lack of knowledge about the mechanical properties of the crust that might justify the observed crustal seismicity a comparison between the revised 1990 1991 earthquakes and the 2002 earthquakes as well as the integration of seismological data with a rheological analysis offer new constraints on the regional seismotectonic context of crustal seismicity in the southern apennines the seismological revision consists of a relocation of the aftershock sequences based on newly constrained velocity models new focal mechanisms of the aftershocks are computed and the active state of stress is constrained via the use of a stress inversion technique the relationships among the observed seismicity the crustal structure of the southern apennines and the rheological layering are analysed along a crustal section crossing southern italy by computing geotherms and two mechanism brittle frictional vs ductile plastic strength rheological profiles the 1990 1991 seismicity is concentrated in a well defined depth range mostly between 15 and 23 km depths this depth range corresponds to the upper pat of the middle crust underlying the apulian sedimentary cover in the footwall of the easternmost apennine thrust system the 3d distribution of the aftershocks the fault kinematics and the stress inversion indicate the activation of a right lateral strike slip fault striking n100 e under a stress field characterized by a sub horizontal n142 trending 1 and a sub horizontal n232 trending 3 very similar to the known stress field of the gargano seismic zone in the apulian foreland the apparent anomalous depths of the earthquakes 15 km and the confinement within a relatively narrow depth range are explained by the crustal rheology which consists of a strong brittle layer at mid crustal depths sandwiched between two plastic horizons this articulated rheological stratification is typical of the central part of the southern apennine crust where the apulian crust is overthrusted by apennine units both the potenza 1990 1991 and the molise 2002 seismic sequences can be interpreted to be due to crustal e w fault zones within the apulian crust inherited from previous tectonic phases and overthrusted by apennine units during the late pliocene middle pleistocene the present strike slip tectonic regime reactivated these fault zones and caused them to move with an uneven mechanical behaviour brittle seismogenic faulting is confined to the strong brittle part of the middle crust this strong brittle layer might also act as a stress guide able to laterally transmit the deviatoric stresses responsible for the strike slip regime in the apulian crust and may explain the close proximity nearly overlapping of the strike slip and normal faulting regimes in the southern apennines from a methodological point of view it seems that rather simple two mechanism rheological profiles though affected by uncertainties are still a useful tool for estimating the rheological properties and likely seismogenic behaviour of the crust

high resolution seismic imaging of the mw5 7 2002 molise southern italy earthquake area evidence of deep fault reactivation 1 we investigate the seismic structure of the mw5 7 2002 molise earthquake area in order to understand the role of e w trending strike slip faults in the tectonics of the southern apennines we apply an innovative seismic migration technique to a high quality data set of earthquakes recorded at a dense local network sp converted waves are migrated in depth to image the high impedance contrast of the apulian platform top buried under the apennines allochthonous cover the continuity of the migrated seismic horizon is broken by vertical steps that we systematically picked along 200 cross sections the best location points of these structures define two main tectonic features the first one is related to nw se oriented normal faults and is consistent with the sw flexure of the foreland lithosphere beneath the orogenic belt the second one indicates that shallow e w oriented trans tensional faults are concentrated directly above the deeper 10 20 km strike slip fault delineating the geometry of a negative flower type structure this fault system delimits a depressed sector of the apulian platform whose geometry is consistent with a pull apart basin inherited from a previous left lateral strike slip tectonic regime the buried structure is analogous to those outcropping in the apulian foreland and in the adriatic offshore to the east this correlation brings new support to the hypothesis of a regional e w trending shear zone cutting the adria plate and suggests that other earthquakes could occur on this or on parallel e w trending strike slip faults

sea ice drift characteristics revealed by measurement of acoustic doppler current profiler and ice profiling sonar off hokkaido in the sea of okhotsk

development of seasonal pack ice in the beaufort sea during the winter of 1991 1992 a view from below subsea sonars moored in the beaufort sea acquired a spatial section of draft across 941 km of sea ice during the winter of 1991 1992 these observations document the development of seasonal sea ice from an open sea surface in october to an average accumulation exceeding 2 5 m draft by early april initially level ice occupied 85 of the profile but continued ridging reduced this fraction to 50 in late winter three modes of level ice were tracked that of seasonal ice whose growth was initiated at freeze up and two others created during openings of the ice field in january and in march the growth of these modes can be closely matched by calculations based on a slab model of ice formation forced using surface meteorological data initially ridge keels were small and widely spaced by midwinter an exponential dependence of keel frequency on draft was obvious e folding scale 2 16 m and the frequency and mean draft of keels had stabilized the maximum keel draft was a modest 17 4 m the low incidence of deep keels at all times is a statistically significant departure from the exponential dependence valid at lesser drafts the truncation point of the exponential relation is related to the draft of the thinnest level ice present in late winter the formation of deeper keels from thick first year ice was apparently precluded by the presence of younger thinner ice which limited the force available for ridge building through calculation of the seaward transport of ice over the sonars the total production of ice in the coastal flaw lead during 1991 1992 was determined to be about 60 of earlier indirect estimates in general the observations revealed winter ice conditions significantly less severe than those found on the periphery of the polar pack only a few tens of kilometers to the north but more so than conditions in a marginal first year ice zone at the same latitude in davis strait

the october november 2002 molise seismic sequence southern italy an expression of adria intraplate deformation a new seismotectonic model for the outer central southern apennines including the epicentral area of the 2002 molise seismic sequence and adjacent foreland is proposed the seismic sequence is related to foreland deformation affecting the adriatic lithosphere such deformation is characterized by active nw se compression resulting in the reactivation mainly as dextral strike slip faults of pre existing east west oriented structures both offshore and onshore one of these structures is interpreted to extend westward and to reach the epicentral area of the recent earthquakes nw se compression ultimately related with africa europe plate convergence and uplift would essentially control the active tectonics of the analysed region

characterising the spatial distribution frequency and geomorphic controls on landslide occurrence molise italy abstract an 815 km2 area in molise central italy was used as a natural laboratory to characterise the lithological topographic and fluvial controls on the spatial distribution and frequency of active landslides in temperate climates the study area is part of the central apennines fold and thrust belt and is characterised by the presence of a tectonic melange of scaly clays known as argille varicolori as well as more competent limestone and sandstone units the area has been subjected to a cumulative stream incision of up to 400 m since the mid pleistocene the landslide inventory was developed by combining satellite image interpretation and existing data sets ground truthed in the field statistical analysis of the inventory data demonstrates that the coupling between landslide occurrence in the area and lithology is strong with landslides occurring 3 10 times more frequently where the mechanically weak argille varicolori scaly clays outcrops compared to other lithologies analysis of the relationship between landslide occurrence and hillslope gradients shows that 50 of all landslides occur on slopes between 10 and 15 despite this interval representing only 30 of hillslope gradients in the study area these results demonstrate the major control that the properties of the regionally significant argille varicolori have on landslide occurrence in the area directly and through their control on hillslope gradients additionally our results show that more than 50 of the landslides occur at a distance of

diagenetic replacement controlled by force of crystallization many diagenetic replacements in sedimentary rocks occur along thin solution films between the authigenic and host phases rather than conventionally invoking bulk pore water undersaturation for host phase dissolution we propose that many diagenetic replacements occur by a force of crystallization controlled replacement mechanism whereby nonhydrostatic stresses resulting from authigenic crystal growth are principally responsible for host phase dissolution this model explains diagenetic features such as the restriction of host phase dissolution to authigenic host crystal contacts and euhedral authigenic crystal faces in planar contact with unreplaced host phases as well as the relative replacement tendencies of some common authigenic minerals

stress and the direction of slip on fault planes the shear stress direction on a fault plane depends only on four of the six components of the stress tensor assuming only that the slip direction marks the shear stress direction on any fault plane and that stress is homogeneous it is possible to estimate these four stress parameters from populations of fault planes with known slip directions as several workers have observed different formulations of the problem may yield varying best fitting stresses and estimates of uncertainty in the simplest case no assumptions are made regarding the orientations of fault planes relative to the stress tensor thus the technique allows for the possibility that the fault planes may be very weak here we present simple analytical and graphical descriptions of the field of admissible fault geometries relative to any four parameter stress model which can be used to illustrate the significance of various inverse strategies in particular this paper explores the effects of using two alternative measures of misfit between an observed fault datum and stress model 1 the pole rotation the angle between the observed and predicted slip direction on the observed fault plane and 2 the minimum rotation the smallest angle between the observed fault geometry and any fault geometry which is consistent with the model by allowing for variation of the fault plane as well as the slip vector the minimum rotation procedure generally achieves a more stable and presumably realistic estimate of the actual discrepancy between a fault observation and stress model than the pole rotation procedure in a test case using 17 earthquake focal mechanisms from the yuii region of eastern taiwan separate inversions based on the two misfit criteria yield different optimum stress models and uncertainty estimates additional constraints on the stress tensor such as the effect of friction can be superimposed on the ones used here

growth processes and melange formation in the southern apennines accretionary wedge abstract the southern apennines owe their present geometry to the subduction of an apulian continental lithospheric slab and are thus best interpreted as an accretionary wedge southward the apenninic thrust front branches on to the still active ionian wedge which is related to the present calabro sicilian subduction the interpretation of conventional seismic reflection profiles and exploration wells combined with geologic field studies biostratigraphy and structural geology provide constraints for a geodynamic model for the post messinian growth of the apenninic prism our model for the apennines is a good analogy for submerged oceanic accretionary prisms in both instances features such as out of sequence thrusts underplating and duplexes are viewed as processes to explain the thickening of accretionary wedges syntectonic terrigenous deposits have accumulated in the synclines developed above the flats of pliocene thrust faults these depocenters represent piggy back basins younger accretion at the eastern border of the accretionary wedge has led to a progressive uplifting and tilting of the already emplaced thrust sheets including a continous westward migration of the depocenters in the piggy back basins during pliocene and early quaternary times a contrary west to east migration of the depocenters locally occurred where preexisting flats of pliocene thrust faults have been refolded rather than only being rotated dewatering processes and effects of overpressures on undercompacted sediment deformations can also be studied in the southern apennines melanges and broken formations form an important component of the trench apparently restricted to the base of tectonic nappes listric normal faults are a major structural element which preserves in combination with the erosion of topographic highs and resedimentation in the piggy back basins a uniform geometric shape critical taper for the prism the age and location of these distensive or gravitational effects are also discussed

the italian cmt dataset from 1977 to the present abstract the ingv harvard european mediterranean regional centroid moment tensor rcmt catalog collects solutions routinely computed since 1997 for earthquakes with moderate magnitude 4 5 m 5 5 in the mediterranean region the database represents an extension to smaller magnitudes of the harvard global cmt catalog based on analysis of seismograms recorded at regional distance and modeling of intermediate period surface waves the catalog includes about 600 events 200 of which in the italian region this study extends the catalog back in time for the italian region as long as made possible by available digital data i e since 1977 with the same analysis and inversion method used for current seismicity as a result we present here 65 new moment tensors for years between 1977 and 1997 these solutions represent 45 of the total number of events analyzed the existing seismograms being often too scarce to allow a stable solution the new dataset includes events in many seismic zones where moderate seismicity had previously been scarcely documented e g the po plain the central to southern apennines and the adriatic sea the complete dataset including previously determined rcmts and cmts represents the seismic deformation in the italian area during the last 25 years

adria seismicity and seismotectonics review and critical discussion abstract we review the most recent advances in research on the seismicity and seismotectonics of adria a large number of earthquakes associated with this lithospheric block occur near the adria boundaries and seismicity has been perhaps the first dataset to allow its identification as a specific lithospheric block adria also hosts significant intraplate seismicity mostly concentrated in specific zones of intraplate brittle deformation the most important being a deformation belt located at the central adriatic latitude and including the gargano promontory and the tremiti islands after a brief excursus on adria seismicity we address some relevant research points and open questions answers to such questions and more in general advances in research on adria seismotectonics and seismicity will not only provide invaluable information for the seismic hazard assessment of this region but also a precious tool to understand the current geodynamics of the central mediterranean

variability of sea ice draft off hokkaido in the sea of okhotsk revealed by a moored ice profiling sonar in winter of 1999 1 using a moored ice profiling sonar along with an adcp a spatial section of draft across 855 km of sea ice was obtained for the first time in the southwestern part of the okhotsk sea near hokkaido in winter of 1999 the draft evolved from 0 20 m in mid february to 1 45 m in late march with the overall value of 0 72 m the draft characteristics were quite different between february and march before and after the period of strong winds the increase of the mean draft from february to march was associated with the increase of deformed ice the maximum draft observed was 17 m ice volume was dominated by the contribution from portions of deformed ice especially in march these results suggest that deformed ice dominated in the region of observation and dynamical processes were mainly responsible for the evolution of draft

seismotectonics of the southern apennines and adriatic foreland insights on active regional e w shear zones from analogue modeling 1 the active tectonics at the front of the southern apennines and in the adriatic foreland is characterized by e w striking right lateral seismogenic faults interpreted as reactivated inherited discontinuities the best studied among these is the molise gondola shear zone the interaction of these shear zones with the apennines chain is not yet clear to address this open question we developed a set of scaled analogue experiments aimed at analyzing 1 how dextral strike slip motion along a preexisting zone of weakness within the foreland propagates toward the surface and affects the orogenic wedge 2 the propagation of deformation as a function of displacement and 3 any insights on the active tectonics of southern italy our results stress the primary role played by these inherited structures when reactivated and confirm that regional e w dextral shear zones are a plausible way of explaining the seismotectonic setting of the external areas of the southern apennines

the aerodynamic roughness of different types of sea ice the aerodynamic roughness for all major types of sea ice is specified on the basis of surface layer measurements from ship and ice floe platforms median neutral surface drag coefficients cdn 1000 for grease and nilas ice are 0 7 and 1 6 small medium large and fused pancake ice have cdn equal to 0 9 1 6 2 4 and 1 9 young ice cdn ranges from 2 3 to 3 1 very smooth first year or multiyear ice with no pressure ridges has cdn equal to 1 5 pack ice has median values of 2 0 and 2 2 for first year and multiyear ice marginal ice zone ice averages 3 1 and 3 4 first year multiyear if unaffected by wave action wave affected ice has cdn values of 4 2 and 4 6 first year multiyear extremely rough multiyear ice in intense shear or compaction regions has cdn equal to 8 0 open ocean areas within 100 km of an ice edge averaged 1 8 while ice free water downwind of ice with small or no waves is 1 4 these values can be adjusted if heat fluxes are present the accuracy of the cdn averages is estimated to be 20 or better

mantle wedge dynamics versus crustal seismicity in the apennines italy 1 in the apennines subduction italy earthquakes mainly occur within the overriding plate along the chain axis the events concentrate in the upper 15 km of the crust above the mantle wedge and focal solutions indicate normal faulting in the foreland the seismogenic volume affects the upper 35 km of the crust focal solutions indicate prevailing reverse faulting in the northern foreland and strike slip faulting in the southern one the deepening of the seismogenic volume from the chain axis to the foreland follows the deepening of the moho and isotherms the seismicity above the mantle wedge is associated with uplift of the chain axial zone volcanism high co2 flux and extension the upward pushing of the asthenospheric mantle and the mantle derived co2 rich fluids trapped within the crust below the chain axis causes this seismicity all these features indicate that the axial zone of apennines is affected by early rifting processes in northern italy the widespread and deeper seismicity in the foreland reflects active accretion processes in the southern foreland the observed dextral strike slip faulting and the lack of reverse focal solutions suggest that accretion processes are not active at present in our interpretation of the apennines subduction the shallower seismicity of the overriding plate is due to the dynamics uprising and eastward migration of the asthenospheric wedge

source analysis of the 2002 molise southern italy twin earthquakes 10 31 and 11 01 1 on october 31 2002 a moderate size earthquake mw 5 8 occurred in molise region southern italy causing loss of young human lives in a school collapse and destructions in several villages the day after a slightly smaller earthquake happened a few kilometers westward from the first one without making strong damage we use a complete set of seismological data global regional and local including both body and surface waves to better understand the source process of these two events we show that the two earthquakes are similar in terms of hypocentral depth focal mechanism and source kinematics moreover the imaged slip zones are almost contiguous which makes the time delay between the two shocks 29 hours an open question the identified updip rupture propagation has amplified the radiation usually created by such mw 5 8 earthquakes at 15 20 km depth we model a maximum acceleration zone in agreement with location of damaged villages

distribution of calcium carbonate in desert soils a model a model that describes the distribution of calcium carbonate in desert soils as a function of dust flux time climate and other soil forming factors shows which factors most strongly influence the accumulation of carbonate and can be used to evaluate carbonate based soil age estimates or paleoclimatic reconstructions models for late holocene soils have produced carbonate distributions that are very similar to those of well dated soils in new mexico and southern california these results suggest that 1 present climate is a fair representation of late holocene climate 2 carbonate dust flux can be approximated by its holocene rate and 3 changes in climate and or dust flux at the end of the pleistocene effected profound and complex changes in soil carbonate distributions both higher carbonate dust flux and greater effective precipitation are required during the latest pleistocene early holocene to explain carbonate distributions in latest pleistocene soils 21 refs 4 figs 1 tab

sea ice thickness in the southwestern sea of okhotsk revealed by a moored ice profiling sonar 1 using a moored ice profiling sonar along with a moored acoustic doppler current profiler a total spatial section of draft across 3334 km of sea ice was obtained in the southwestern sea of okhotsk near hokkaido in the winters of 1999 2001 using this draft data set the average draft and keel statistics are discussed in this sea for the first time the mean draft was 0 60 m which corresponds to the thickness of 0 71 m over the three winters with the range of 0 49 0 72 m for each winter the classification of level and deformed ice reveals a small range of the monthly mean level ice draft 0 18 0 27 m and the dominance of the deformed ice in terms of volume 80 the mean draft varied with the areal ratio of the deformed ice fairly well these results suggest that dynamic processes such as ridging and rafting are important for the evolution of draft in the region of observation the observed draft probability density distribution and keel statistics show that the thick ice ratio and keel frequency are lower than the similar data in polar regions and closer to those observed in davis strait west of greenland along with the ice concentration and speed derived from the satellite data the southward ice transport to the southwestern sea of okhotsk is estimated on the basis of the observed sea ice thickness the estimated ice transport ranged from 15 to 70 km3 in each winter the heat and freshwater transport associated with the ice transport ranged from 3 9 1017 to 1 8 1018 j and from 12 to 57 km3 respectively

ice drift and regional meteorology in the southern bering sea results from mizex west in february 1983 a multifaceted study of the air ice ocean interaction was made in the southern bering sea the study mizex west addressed a broad spectrum of physical problems related to the bering sea marginal ice zone miz as a part of that study an array of eight argos tracked floes on a scale of 50 km provided information on the mesoscale behavior of the ice pack wind and current measuring platforms on two of the floes gave detailed information on the forces on individual floes which were compared with the larger scale motions under relatively steady northeast winds and with weak or negligible regional currents the floes accelerated considerably as they crossed the miz the array showed little distortion even though it skirted around st matthew island and changed trajectory direction by over 90 during the 12 day study period similarly individual floes remained within 20 of their original orientation although their angular motions were erratic and often rapid a baroclinicly forced acceleration of the wind over the miz contributed to floe acceleration the relative currents at 2 and 6 m under the ice were highly variable and random in time although well correlated in depth one of the floes was much smoother than the other and higher winds and currents were noted at the smoother floe the motion of the floes reflect strong coupling to the currents at tidal and lower frequencies and low frequency greater than 6 hours response to the wind both floes drifted to the right of the mean wind by approximately 30 at about 4 of the wind speed at 3 m and relative wind and current directions were within 20 of being colinear traits that are consistent with free drift hypothesis using quadratic drag representations for wind and current stress the near colinearity allowed calculation of the ratio of the air ice to ice water drag coefficients ca cw relative to measurement heights of 3 m and 2 m for the rough floe this ratio changed in mean from 0 06 to 0 2 in its movement to the miz for the smooth floe the variation in the ratio was less from 0 14 to 0 2 however for the rough flow the angle between wind and current was generally less than 180 and for the smooth flow it was greater it is possible that another type of drag related to the bow effect of the floe pushing through the water can account for this observation finally the motion of the ice floes and ice edge are compared by examination of satellite photos two regions of the ice pack one thick with rafting and rubble one thin and broken showed a ratio of edge velocity to floe velocity of 0 64 and 0 43 respectively thinner ice overtakes the edge and melts more rapidly than the thicker ice a simple thermodynamic model explains this observation

tectonic evidence for the ongoing africa eurasia convergence in central mediterranean foreland areas a journey among long lived shear zones large earthquakes and elusive fault motions an edited version of this paper was published by agu copyright 2010 american geophysical union

solution slip and separations on strike slip fault zones theory and application to the mattinata fault italy we present a set of relationships to determine the component of slip and separations generated by the cleavage controlled volume contraction in strike slip fault zones the fault walls can translate toward each other along the cleavage normal axis of maximum shortening as rock is dissolved by pressure solution along patterned cleavage surfaces within strike slip fault zones the fault zone shortening produces an apparent slip and possible separations of reference stratigraphic surfaces across the fault zone solution related slip and separations can differ in magnitude and have either the same or the opposite sense these discrepancies depend upon the amount of fault zone shortening and upon the angles between the fault and the shortening axis and between the fault and the reference stratigraphic surface separations can be considerable at any scales even for very low amounts of fault zone thinning apparent slip can be appreciable for large amounts of fault zone thinning and or high fault to cleavage incidence angles with the proper geometrical conversions the relationships here presented can apply to any fault type the application of this technique to the left lateral mattinata fault italy demonstrated that both left and right lateral strike separations can occur along the fault even for low amounts of fault zone contraction by rock dissolution q 2002 elsevier science ltd all rights reserved

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

relationship between sea ice motion and geostrophic wind in the northern hemisphere this paper presents maps showing the relationship between sea ice motion derived from defense meteorological satellite program dmsp special sensor microwave imager ssm i imagery and the geostrophic wind in the northern hemisphere for seven winters 1991 92 1997 98 the sea ice motion is highly correlated with the geostrophic wind except for some coastal regions overall the direction of the ice motion is nearly parallel to the wind an obvious contrast between seasonal ice zones and the interior of the arctic is observed in the speed reduction factor ratio of ice speed to wind speed which is probably caused by the spatial variation of internal ice stress surface ocean currents are also derived by subtracting the wind effect from the ice motion

the september 27 2012 ml 4 1 benevento earthquake a case of strike slip faulting in southern apennines italy abstract on september 27 2012 at 01 08 utc a m l 4 1 earthquake started a seismic sequence approximately 10 km east of the city of benevento in southern apennines italy during the following four days about 40 events with m l ranging between 1 3 and 4 1 were detected in the same area where the seismic hazard is one of the largest of the italian peninsula and where several historical and destructive events took place in order to investigate the seismicity spatio temporal pattern and to identify the seismogenic source geometry a detailed analysis was performed integrating data recorded at three different seismic networks the earthquakes were relocated using the double difference technique and focal mechanism solutions were obtained by the moment tensor inversion also to better understand the rupture process seismic source parameters were estimated and apparent source time functions were inverted to retrieve the slip distribution for the largest magnitude event our results show the existence in the study area of roughly e w striking fault plane with a right lateral strike slip kinematics seated at mid crustal depths 10 20 km revealing a characteristic seismicity quite different from that typically associated to the outcropping nw se striking active normal faults that are responsible of moderate to large earthquakes in the southern apennines axial sector in this work we address questions concerning i the presence in the benevento area of a mid crust seismogenic strike slip fault previously unrecognized ii its link to the regional seismotectonic setting and iii the existence of a strike slip tectonic regime that uniformly extends in the footwall of the apennines thrust at relevant depth not only in the apulian foreland as demonstrated to date but also under the mountain chain axial zone

the seismogenic structure of the 2013 2014 matese seismic sequence southern italy implication for the geometry of the apennines active extensional belt

active fragmentation of adria the north african promontory central mediterranean orogen global positioning system gps velocities indicate that adria no longer behaves as a rigid tectonic indenter into southern europe and is divided into northwestern and southeastern velocity domains differential motions are recognized in a velocity field determined from the peri tyrrhenian geodetic array ptga and international gps service igs sites in the circum tyrrhenian region of the central mediterranean and published gps velocities from the eastern adriatic coast in a fixed eurasian reference frame ptga and igs site velocities in sicily and southern italy are as much as 10 mm yr in a northward direction similar to gps velocities along the eastern coast of the adriatic sea in contrast velocities in northern italy are small or statistically insignificant and similar to velocities in sardinia and corsica outboard of western adria the tectonic boundary dividing adria is seismically active and passes around the southern and eastern margins of the tyrrhenian basin crosses central italy extends into the adriatic sea and follows the western margin of the dinaride tectonic belt north to the gulf of venice the eastern margin of adria is approximately located and follows the axis of the central dinaric alps southeast to the hellenic arc southeastern adria has a velocity related to northward motion of africa whereas northwestern adria has negligible differential motion in the eurasian frame and now is part of the alpine collage of southern europe

seismogenic sources in the adriatic domain abstract we present an overview of the seismogenic source model of the adriatic domain included in the latest version of the diss database http diss rm ingv it diss and in the european share database http diss rm ingv it share the model consists of composite and individual seismogenic sources located inside and along the margins of the adria plate in order to locate and parameterize the sources we integrated a wide set of geological geophysical seismological and geodynamic data either available from published literature or resulting from our own field work seismic profile interpretations and numerical modelling studies we grouped the sources into five regions based on geometrical and kinematic homogeneity criteria seismogenic sources of the central western adriatic north eastern adriatic eastern adriatic and central adriatic regions belong to the northern apennines external dinarides and offshore domains respectively they are characterized by nw se strike reverse to oblique kinematics and shallow crustal seismogenic depth seismogenic sources of the southern western adriatic region instead are e w striking dextral strike slip faults cutting both the upper and lower crust the fastest moving seismogenic sources are the most southern thrusts of the eastern adriatic and the strike slip sources of the southern western adriatic while the seismogenic sources of the central adriatic exhibit the lowest slip rates estimates of maximum magnitude are generally in good agreement with the historical and instrumental earthquake records except for the north eastern adriatic region where seismogenic sources exhibit a potential for large earthquakes even though no strong events have been reported or registered all sources included in the database are fully geometrically and kinematically parameterized and can be incorportaed in seismic hazard calculations and earthquake or tsunami scenario simulations

an improved method for determining the regional stress tensor using earthquake focal mechanism data application to the san fernando earthquake sequence the orientations of fault planes and slip directions indicated by a population of earthquake focal mechanisms can be used to determine best fit regional principal stress directions and r 2 1 3 1 a measure of relative stress magnitudes under the assumption of uniform stress in the source region this analysis allows for the possibility that failure occurs on preexisting zones of weakness of any orientation in the inversion we perform a grid search of stress models to find the one which requires the smallest total rotation of all the fault planes that is needed to match the observed and predicted slip directions the method allows for errors in orientations of both the fault planes and slip directions we have an objective means for identifying the more likely of the two possible fault planes from each focal mechanism relative to a given stress model thus we do not face the problem of ambiguity of nodal planes which plagues other analyses of this kind by using a grid search of stress models rather than a linearization scheme we are able to perform a realistic error analysis and thus establish confidence limits for the preferred regional stresses the method can be used to investigate possible stress inhomogeneities during earthquake sequences by analyzing subsets of the data population the technique has been applied to 76 events from the san fernando earthquake sequence for which we have found best fit stresses plunge and azimuth 1 7 187 2 27 281 3 62 84 and r 0 65 the average misfit between this stress model and all the data is about 8 and all but eight of the aftershocks have misfits of less than 20 these values are considerably less than the uncertainty of the focal mechanism determinations therefore significant stress inhomogeneities are not required by the data our analysis does not support the suggestion of a change in stresses during the aftershock sequence as proposed by others on the basis of an apparent change in focal mechanisms

real time determination of seismic moment tensor for the italian region this work has been funded by the 2005 2007 dpc s4 and 2008 2010 dpc s3 italian civil protection contracts

pedogenic replacement of aluminosilicate grains by caco3 in ustollic haplargids south central montana u s a abstract a chronosequence of calcic soils formed on granitic glaciofluvial terrace deposits of rock creek and the clarks fork in south central montana shows progressive replacement of aluminosilicate parent material grains by calcium magnesium carbonate the terraces range from late pliocene to holocene in age as dated by tephrochronology correlation and stream incision rates replacement is first seen in soils that are as old as 120 000 yr the amount and degree of replacement increase in soils older than 120 000 yr along with the development of calcic horizons under the petrographic microscope carbonate replacement of quartz feldspars and the groundmass of andesite grains in rock creek soils is shown by embayed grains networks of carbonate along cracks and between parts of polycrystalline grains and optically aligned grain fragments within carbonate masses microprobe data suggest that silica is released by replacement because it is absent from carbonate filled spaces and is depleted in corrosion pits little microscopic evidence exists to support displacement of framework grains by carbonate because fragments of a single grain are rarely rotated out of optical alignment in the calcic soils of rock creek k fabric grains floating in a carbonate matrix may form by both replacement and displacement

recent seismicity and crustal stress field in the lucanian apennines and surrounding areas southern italy seismotectonic implications abstract we analyzed the instrumental seismicity of southern italy in the area including the lucanian apennines and bradano foredeep making use of the most recent seismological data base available so far p and s wave arrival times recorded by the italian national seismic network rsnc operated by the istituto nazionale di geofisica e vulcanologia ingv were re picked along with those of the saptex temporary array deployed in the region in the period 2001 2004 for some events located in the upper val d agri we also used data from the eni agip oil company seismic network we examined the seismicity occurred during the period between 2001 and 2006 considering 514 events with magnitudes m 2 0 we computed the v p v s ratio obtaining a value of 1 83 and we carried out an analysis for the one dimensional 1d velocity model that approximates the seismic structure of the study area earthquakes were relocated and for well recorded events we also computed 108 fault plane solutions finally using 58 solutions the most constrained we computed regional stress field in the study area earthquake distribution shows three main seismic regions the westernmost lucanian apennines characterized by high background seismicity mostly with shallow hypocenters the easternmost below the bradano foredeep and the murge with deeper and more scattered seismicity and finally the more isolated and sparse seismicity localized in the sila range and in the offshore area along the northeastern calabrian coast focal mechanisms computed in this work are in large part normal and strike slip solutions and their tensional axes t axes have a generalized ne sw orientation the denser station coverage allowed us to improve hypocenters determination compared to those obtained by using only rsnc data for a better characterization of the crustal and subcrustal seismicity in the study area

seismic activity in the transition zone between southern and central apennines italy evidences of longitudinal extension inside the ortona roccamonfina tectonic line abstract we analyze the 1997 2006 seismicity of the transition zone between southern and central apennines which is one of the most active seismic areas of italy our aim is to add information on the seismotectonic picture of this area seismic activity is characterized by single events with m

a critical revision of the seismicity of northern apulia adriatic microplate southern italy and implicationsfor the identification of seismogenic structures abstract northern apulia is an emerged portion of the adriatic microplate representing the foreland foredeep area of a stretch of the apennine chain in southern italy the interaction between the relatively rigid microplate and the contiguous more deformable domains is responsible for the intense seismicity affecting the chain area however strong sometimes even disastrous earthquakes have also hit northern apulia on several occasions the identification of the causative faults of such events is still unclear and different hypotheses have been reported in literature in order to provide guidelines and constraints in the search for these structures a comprehensive re examination and reprocessing of all the available seismic data has been carried out taking into consideration 1 the characteristics of historical events 2 the accurate relocation of events instrumentally recorded in the last 20 years 3 the determination of focal mechanisms and of the regional stress tensor the results obtained bring to light a distinction between the foreland and foredeep areas in the first region there is evidence of a regional stress combining nw compression and ne extension thus structures responsible for major earthquakes should be searched for among strike slip faults possibly with a slight transpressive character these structures could be either approximately n s oriented sinistral or e w dextral faults in the foredeep region there is a transition toward transtensive mechanisms with strikes similar to those of the previous zone or maybe also towards nw oriented normal faults more similar to those prevailing in the southern apennine chain in relation to a dominant ne extension this appears to be the effect of a reduction of the nw compression probably due to a decrease in efficiency of stress transmission along the more tectonised border of the adriatic microplate

rates of geodetic deformation across active faults in southern italy abstract active deformation in southern italy is accommodated by a distributed number of faults with low moderate slip rates outcropping extensional faults and mostly blind transcurrent faults are mapped within a western or axial and an eastern domain respectively we use a combination of continuous 2001 00 2011 84 and episodic 1995 68 2010 79 gnss observations to firstly estimate the geodetic deformation rate on 32 faults geodetic results were successively compared with geological displacement estimates in agreement with seismological and geological information a net spatial segregation emerges between the extensional axial belt and the eastern domain where strike slip faults are geodetically active although uncertainties are at times large average displacement rates show broadly consistent patterns within both domains a longitudinal gradient in extension rate is observed for the axial fault array with two sectors of higher magnitude 0 8 1 7 mm yr for individual faults this result is consistent with geological observations and supports the notion that extension occurs in discrete patches faults of the eastern domain have lower few 0 1 to 1 2 mm yr strike slip rates and an eastward decreasing extensional component but significant geodetic displacement is detected in areas lacking clear evidence of activity few faults with 1 2 mm yr extension rate are locally found in the eastern domain but based on their limited length and on inconsistency with seismology and geology they are considered as due to deep seated gravitational spreading for crustal faults although geodetic slip and moment rates are larger than geological rates the broad trend of long to short term rates is similar indicating the feasibility of geodetic analysis to contribute estimating fault slip rate and testing tectonic models in the region whereas the western domain extension is thought to be controlled by potential energy related to the tyrrhenian moho uplift beneath the apennines strike slip in the east is related to shear on inherited faults within the adriatic crust

the underside topography of sea ice over the continental shelf of the beaufort sea in the winter of 1990 a spatial section of draft across 348 km of sea ice was obtained by moored subsea sonars in the beaufort sea in the winter of 1990 the ice field was a mixture of first year and multiyear types with mean draft of the order of 3 m level ice of 0 to 4 m draft occupied approximately 50 of the section within this fraction draft values of 0 and 1 5 m were most common while at 2 to 3 m draft a noticeable contribution was made by rafted first year ice deformed ice was observed to a maximum draft of nearly 27 m keels within the section were identified using both the rayleigh criterion and a new criterion based on level ice both criteria defined exponentially distributed populations but with different e folding scales the observations revealed an ice cover whose statistical properties are consistent with other data from the periphery of the polar pack in the beaufort sea but which are much more severe than those of ice found in the seasonal ice zone only a few tens of kilometres to the south the cross sectional shape of individual keels was highly variable but on average the distribution of ice within a keel was an exponential function of draft the topography of both first year and old ice subsections of the data was fractal in character with a dimension of about 1 5 for both ice types the average mass of sea ice per unit area was estimated as 2540 2970 kg m 2 with 68 73 of this mass contributed by deformed ice the large uncertainties in these estimates arise because the porosity of keels and the burden of snow or melt water upon the ice are not known

moment tensor inversions for local earthquakes using surface waves recorded at terrascope we have developed a method to determine moment tensors for local earthquakes using short period 10 to 50 sec surface waves recorded at terrascope stations to correct for the substantial lateral variations in crustal structure we applied phase corrections to the data using a regionalized phase velocity model we have determined moment tensors for over 180 events in the last 3 yr in southern california for magnitudes as small as 3 2 and as large as 6 5 the results are consistent with those obtained from first motion data as well as other waveform inversions when continuous data telemetry from the stations becomes available this method can yield moment tensors for earthquakes in southern california and adjacent regions within minutes after the occurrence of an event our results confirm the relation log m o seismic moment 1 5m l local magnitude obtained by an earlier study

dynamic model of the genesis of calcretes replacing silicate rocks in semi arid regions abstract in both pedogenic and groundwater calcretes calcium carbonate precipitates in voids or displacing other grains or replacing underlying parent silicates replacement textures are widespread in pedogenic calcrete many calcretes also contain magnesium layer silicates and minor chert we present a reaction transport model that accounts for the genesis of replacement in calcretes and for their mineralogy replacement is difficult to account for geochemically because it requires simultaneous removal of large amounts of silicates and import of also large amounts of caco 3 in the model the genesis of replacement is directly related to seasonally alternating dry wet climates and to appropriate groundwater or circulating soil water compositions in a dry season water evaporation causes caco 3 and sepiolite or attapulgite to precipitate if groundwater contains enough mg 2 sepiolite precipitation by the chemical divide mechanism depletes sio 2 aq resulting in the dissolution of parent silicates in the following wet season sepiolite dissolves fast and silica and cations are flushed away by rainwater making room for caco 3 precipitation in the next dry season as climate cycles repeat caco 3 is accumulated and silicates are removed the sepiolite or attapulgite or mg smectite serves as a temporary storage of silica between seasons if the groundwater contains too little aqueous mg then the model predicts growth of calcium carbonate without removing silicates thus producing void filling and or displacive textures instead of replacement the model consists of a set of nonlinear partial differential equations taking account of mass conservation dispersion advection rainwater infiltration evaporation and the kinetics of mineral reactions the hydrodynamics of unsaturated media is applied in determining water flow in calcrete profiles wet dry seasonal changes are incorporated by alternating the upper boundary conditions the model successfully produces the mineral and textural zonation observed in many calcretes namely at the bottom of the profile the parent rock is first replaced by sepiolite only part of which is in turn replaced by calcite whereas at the top of the calcrete the sepiolite is itself completely replaced by the calcite which appears to directly replace the parent rock the model can produce calcrete near the earth s surface well above the water table low p co 2 intensive evaporation and long dry seasons all are predicted to produce thicker calcretes calcretes constitute an effective geochemical tool that via replacement removes parent silicate rocks and shapes the landscape of semi arid countries the model herein provides a mechanism that accounts for the efficiency of replacement in removing silicates

dynamic propagation and interaction of a rupture front on a planar fault we investigate the propagation and interaction of a rupture front that propagates on a planar fault using a boundary integral equation method we show first that the rupture velocity is controlled by a delicate balance between consumed fracture energy and supplied elastic strain energy a very sharp boundary in parameter space separates models in which ruptures stop spontaneously from those in which rupture propagates at super shear speeds the transition zone or bifurcation is shown to be stable with reference to small scale heterogeneities of the stress field using the relations derived from this analysis we examined the mechanism to generate high slip rate when two rupture fronts collide we found that collision at slow rupture velocities causes abrupt stress drop and generates high slip rates however these features tend to be moderated by large slip weakening distances finally we simulated rupture front focusing at the initial stages of an earthquake a phenomenon that may cause high slip rate pulses and therefore generate high frequency seismic waves we assume a pre slip region in which stress has decreased quasi statically to the dynamic friction level due to this pre slip strong stress concentration has developed around the pre slip area and a dynamic rupture starts at a certain point on the rim of the pre slip region we observe rupture front focusing that generates high slip rate pulses we also studied a double pre slip model in which two pre slip regions exist close to each other before the earthquake and found that multiple pre slips enhance the focusing effects

reactivation of deep faults beneath southern apennines evidence from the 1990 1991 potenza seismic sequences we relocate the 1990 1991 potenza southern apennines belt italy sequences and calculate focal mechanisms this seismicity clusters along an e w dextral strike slip structure second order clusters are also present and reflect the activation of minor shears the depth distribution of earthquakes evidences a peak between 14 and 20 km within the basement of the subducting apulian plate the analysed seismicity does not mirror that of southern apennines which include nw se striking normal faults and earthquakes concentrated within the first 15 km of the crust we suggest that the e w faults affecting the foreland region of apennine propagate up to 25 km of depth the potenza earthquakes reflect the reactivation of a deep preexisting fault system we conclude that the seismotectonic setting of apennines is characterized by nw se normal faults affecting the upper 15 km of the crust and by e w deeper strike slip faults cutting the crystalline basement of the chain

atmospheric boundary layer structure and drag coefficients over sea ice this paper estimates the air sea drag coefficient for first year ice from recent aircraft measurements and reconciles the range of observed drag coefficients 103cd 1 2 3 7 referenced to 10 m for all sea ice types based on ice roughness and seasonal meteorology for the purpose of sea ice modeling it is necessary to define an effective drag coefficient which relates regional stress to regional wind because sea ice is heterogeneous on scales less than 20 km regional stress is influenced by the distribution of surface roughness the buoyancy flux from quasi periodic leads and external atmospheric conditions principally the inversion height 103cd is 1 3 1 5 for smooth ice but is much greater for nonflat surfaces for wind speeds greater than 5 m s and air temperatures below freezing the effective 103cd is 2 5 3 0 for nearly continuous pack ice such as first year ice in seasonal ice zones and central arctic basin the range of values of 103cd is 3 0 3 7 for unstable boundary layers typical of off ice winds in the marginal ice zone miz or even greater if the ice has been broken by a recent storm cd values at the lower end of these ranges are associated with low inversion heights these coefficients are confirmed by 103cd of 2 9 2 5 and 3 1 for first year sea ice calculated from gust probe data collected by the noaa p 3 aircraft interior to the inner miz in the bering sea during the marginal ice zone experiment mizex west in february 1983 and 103cd of 2 6 for the arctic calculated from arctic ice dynamics joint experiment aidjex aircraft data for february 1976 the effective drag coefficient with the presence of even a small concentration of sea ice is greater than the oceanic value as shown by a 103cd of 2 2 calculated from noaa p 3 gust probe data over a 40 km track of 0 4 ice concentration in the outer miz of the greenland sea in june 1984 during mizex 84 the relation of surface wind and stress to the geostrophic wind for shallow inversion heights typical of high latitudes is reviewed with a turbulent closure atmospheric boundary layer model the winter arctic is typified by low inversions 100 m low geostrophic drag coefficients and large geostrophic surface wind turning angles with low functional dependence on surface roughness seasonal ice zones are typified by a more modest influence of the inversion on boundary layer characteristics

why allanite may swindle about its true age allanite from the tertiary rieserferner pluton austrian alps is texturally and chemically heterogeneous continuous covariation trends reflect coupled substitution of ca al vs fe ree th in allanite whereas systematic variations in la nd demonstrate the increasingly stronger depletion of lree in the melt during its crystallization allanite samples corrected for 206pbexcess from two rocks scatter in the concordia diagram and define discordias from 31 8 0 4 ma and 32 2 0 4 ma to ca 540 ma the apparent inheritance does not originate from the inclusion of older allanite or a high phase such as monazite xenotime or zircon but from the incorporation of radiogenic pb originating from a precursor since allanite requires a high enrichment of th u and lree it may form at the expense of a th lree rich precursor in metamorphic rocks or where such a phase had dissolved in melts likely precursors acquire with time radiogenic pb isotopic compositions this pb if incorporated in the product mineral may give the illusion of inheritance the allanite samples from the rieserferner pluton show a tendency from high th ucalc 30 50 in samples with an alpine age to low th ucalc 4 12 in samples with distinct inheritance this relation between extent of inheritance and apparent th ucalc indicates a lower th ucalc for a possible precursor falling into the th u range commonly encountered for monazite precursor monazite would have originated from assimilated palaeozoic rocks and give rise to localized enrichments of th and lree in the melt thus eventually enabling the growth of allanite

geodetic strain in peninsular italy between 1875 and 2001 1 we determine geodetic strain in peninsular italy by the gps reoccupation of the first order triangulation network of italy installed from 1860 the uncertainties in the original measurements about 3 ppm and the time span between the two observations imply that tectonic signals larger than about 0 03 ppm yr are resolvable along the apenninic belt where the largest earthquakes are concentrated the geodetic deformation has a clear and consistent strain pattern between adjacent regions well above the uncertainties and shows a pervasive ne sw extension along the tyrrhenian and adriatic coasts the geodetic signal is not homogeneous and is comparable with the uncertainty in the original measurements seismic deformation calculated over the same time interval agrees well with estimated extensional direction but the magnitudes of geodetic and seismic strain differ suggesting that in part of the apennines significant strain accumulation over the past 130 years may not have been released in earthquakes

three dimensional vp and vp vs models of the upper crust in the friuli area northeastern italy summary 3 d images of p velocity and p t os velocity ratio have been produced for the upper crust of the friuli area northeastern italy using local earthquake tomography the data consist of 2565 p and 930 s arrival times of high quality the best fitting v p and v p v s 1 d models were computed before the 3 d inversion v p was measured on two rock samples representative of the investigated upper layers of the friuli crust the tomographic v p model was used for modelling the gravity anomalies by converting the velocity values into densities along three vertical cross sections the computed gravity anomalies were optimized with respect to the observed gravity anomalies the crust investigated is characterized by sharp lateral and deep v p and v p v s anomalies that are associated with the complex geological structure high v p v s values are associated with highly fractured zones related to the main faulting pattern the relocated seismicity is generally associated with sharp variations in the v p v s anomalies the v p images show a high velocity body below 6 km depth in the central part of the friuli area marked also by strong v p v s heterogeneities and this is interpreted as a tectonic wedge comparison with the distribution of earthquakes supports the hypothesis that the tectonic wedge controls most of the seismicity and can be considered to be the main seismogenic zone in the friuli area

satellite derived maps of arctic and antarctic sea ice motion 1988 to 1994 standard image processing methods applied to 85 5 ghz special sensor microwave imager ssm i data provide previously unseen details about sea ice motion in the arctic and southern oceans means calculated from daily ice motions for 1988 1994 confirm the basic circulation patterns established from drifting stations and buoys but extend these observations to illustrate less well known transport patterns in the arctic coastal zones and sub arctic seas in the antarctic the gridded motion fields show a nearly continuous westward transport along the antarctic coast with well defined regions of exchange between this east wind drift and the antarctic circumpolar current this detailed view of mean ice motion in the southern ocean is unique and presents a comprehensive overview not previously available for antarctic ice motions

high precision differential earthquake location in 3 d models evidence for a rheological barrier controlling the microseismicity at the irpinia fault zone in southern apennines

evolution of calcrete in palaeodrainages of the lake napperby area central australia abstract carbonate lithofacies developed along the trunk valley of palaeodrainage channels as well as those adjacent to gypsite facies in the lake napperby drainage basin in central australia show wide ranges of sedimentary characteristics reflecting significant variation in depositional environments sedimentological and geochemical characterization of the calcrete lithofacies in this drainage area indicate that whereas variations in bedrock morphology are important in overall distribution of the phreatic and vadose calcrete varieties faulting and basin adjustments since the early quaternary may also have played a significant role in redistribution of the hydrologic zones and hence the evolution of these calcretes accordingly phreatic calcretes which initially precipitated from laterally moving groundwaters along the palaeodrainage channels undergo systematic mineralogical changes due to direct evaporative precipitation and diagenetic displacement replacement processes mainly dolomitization and silicification under present hydro chemical conditions within the zone of grounwater fluctuations however lateral and downward shifts in groundwater flow due to excessive volumetric expansion and reduction in effective permeability of calcrete may ultimately result in isolation of the calcrete like those observed from the eastern margins of the lake the evolution of the vadose calcretes is thereafter topographically controlled and relates to mobilization and redistribution of earlier deposited calcretes under present meteorological conditions

the 8 june 2008 mw 6 4 earthquake in northwest peloponnese western greece a case of fault reactivation in an overpressured lower crust abstract on 8 june 2008 a strong m w 6 4 earthquake occurred in the area of northwest peloponnese western greece the event originated in the lower crust and was caused by the rupture of a previously unknown fault probably inherited from past tectonic phases in this study we perform a stress inversion of all available focal mechanisms in this area in order to obtain an estimate of the regional stress field it is shown that the maximum principal stress axis has an azimuth of n273 e and forms an angle of 63 with the fault s strike which is well constrained by seismological observations this implies that the fault was severely misoriented with respect to the prevailing stress field assuming friction coefficients in the range 0 65 0 85 calculation of pore fluid factors for a variety of input parameters seems to confirm the presence of elevated fluid pressure near the hypocenter because they reach superhydrostatic to lithostatic values 0 80 1 0 the source of these fluids is probably of deep origin and may have to do with upper mantle degassing this suggestion is supported by the presence of mantle helium in spring waters close to the epicenter and by low pn velocities consistent with partially molten mantle beneath northwest peloponnese