reassessing the rupture process of the 2009 l aquila earthquake mw 6 3 on the paganica fault and investigating the possibility of coseismic motion on secondary faults the kinematic rupture of the l aquila earthquake on the paganica fault is reassessed with a highly comprehensive set of data this very complete dataset is also used to explore the possibility that secondary faults may be involved in the coseismic process the main characteristics of the slip distribution of the paganica normal fault found by previous studies are confirmed an initial propagation around and up dip of the hypocenter associated with a high velocity rupture 3 5 km s a main asperity centered about 6 7 km southeast of the hypocenter rupturing in the subsequent stage with a maximum slip of nearly 1 5 m a total rupture measuring about 15 km along strike and 12 km along dip and an overall low average velocity rupture 2 km s the statement that the main features of the slip distribution are confirmed by different studies based on distinct inversion schemes is by itself an achievement knowing that many past studies provided strongly discrepant slip maps for common events moreover we focus specifically on the existence of slip at shallow depth and its relations with the other known active faults in the vicinity of the paganica fault we find that 1 as found in previous studies shallow slip near the ground surface up dip of the hypocenter is incompatible with the available synthetic aperture radar interferograms and 2 the only secondary fault that is likely to have been activated during the mainshock is the san gregorio synthetic fault located 2 3 km southwest of the paganica fault online material figures of waveform fitting using different velocity models time versus distance distribution of slip from the single fault model variations in the geometry of the paganica fault geometry of complex faults models and geodetic data modeling uncertainty on the slip value and the rupture time effect of noise on resolution tests quantification of the improvement on the gps data fitting with the preferred two faults model with respect to the single fault model and a posteriori modeling of leveling data

radar interferometric mapping of deformation in the year after the landers earthquake although the 1992 landers california earthquake sequence occurred in an area well sampled by geodetic networks1 3 the postseismic deformation in the months following the earthquake has been measured at only 15 geodetic stations4 another shortcoming in the geodetic coverage occurs west of the primary rupture where the existing geodetic observations suggest but cannot resolve sympathetic slip on secondary faults1 such measurements which are needed to place the landers earthquake sequence in the context of a recurring seismic cycle in california can be obtained with the dense spatial coverage provided by satellite radar interferometry5 9 here we present radar maps of the surface deformation field which reveal features that would otherwise have been poorly sampled particularly if the earthquake had occurred in a less accessible area we see triggered slip at the level of several centimetres as far as 100 km from the primary rupture and can resolve the geodetic signal of at least one small magnitude 5 aftershock the amount of surface slip following the main shock is less than a decimetre and is consistent with an exponential decay time of several months for the postseismic deformation

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

small scale deformations associated with the 1992 landers california earthquake mapped by synthetic aperture radar interferometry phase gradients the landers earthquake mw 7 3 occurred on june 28 1992 and ruptured nearly 100 km of previously mapped and unmapped faults in the mojave desert we use synthetic aperture radar interferometry insar to examine the cumulative surface deformation between april 24 and august 7 1992 in a 100 100 km region surrounding the northern portion of the earthquake rupture also we introduce a technique for manipulating sar interferograms to extract short wavelength displacement information this technique involves computation and subsequent combination of interferometric phase gradient maps the insar results show significant deformation signatures associated with faults fractures dry lake beds and mountainous regions within 75 100 km of the main rupture using the phase gradient method we are able to extract small scale deformation patterns near the main rupture many of the preexisting mapped faults within 50 km of the main rupture experienced triggered slip these include the old woman lenwood johnson valley west calico and calico faults the insar results also indicate right lateral offsets along secondary fractures trending n ne within the left lateral zone of shear between the main rupture and the johnson valley fault additionally there are interesting interferogram fringe signatures surrounding troy dry lake and coyote dry lake that are related to deformation of dry lake beds

organic matter sources to the water column and surficial sediments of a marine bay sediment trap and net plankton samples were collected monthly for a year at three depths in a marine bay dabob bay washington these materials and subsamples from a sediment box core were analyzed for lignin oxidation products as well as elemental and stable carbon isotope compositions the sediment core was compositionally uniform over its entire 50 cm length the elemental and lignin compositions of the sediment trap and core samples indicate nitrogen rich atomic c n 7 5 plankton derived organic matter mixed with vascular plant debris at most vascular plant debris accounts for 10 nonwinter months to 35 winter months of the total organic carbon in the upper water column 30 m sediment trap samples and consists predominantly of gymnosperm wood along with some nonwoody gymnosperm tissues and angiosperm woods bulk land derived organic matter in dabob bay contains a maximum of 50 vascular plant debris and comprises an average of one third of the total organic carbon in the sediment trap samples and two thirds of the total organic carbon in the underlying sediments lignin in the sediment trap and core samples shows evidence from elevated vanillic acid vanillin ratios of white rot fungal degradation before but not after introduction to the water column at the study site vascular plant debris introduced to the bay has already lost almost half of its initial bulk polysaccharide glucose yields are particularly low whereas rhamnose and fucose are obtained in excess of expected yields and must have additional sources lignin and neutral sugars together account for 20 of the total organic carbon in the sediment trap and core samples overall the sediments of dabob bay compositionally resemble the gymnosperm wood rich particulate material introduced to the overlying water column during winter and poorly record the input of plankton and other types of vascular plant debris during nonwinter months

deep reaching versus vertically restricted quaternary normal faults implications on seismic potential assessment in tectonically active regions lessons from the middle aterno valley fault system central italy abstract we investigate the middle aterno valley fault system mavf a poorly investigated seismic gap in the central apennines adjacent to the 2009 l aquila earthquake epicentral area geological and paleoseismological analyses revealed that the mavf evolved through hanging wall splay nucleation its main segment moving at 0 23 0 34 mm year since the middle pleistocene the penultimate activation event occurred between 5388 5310 b c and 1934 1744 b c the last event after 2036 1768 b c and just before 1st 2nd century ad these data define hard linkage sensu walsh and watterson 1991 peacock et al 2000 walsh et al 2003 and references therein with the contiguous subequana valley fault segment able to rupture in large magnitude earthquakes up to 6 8 that did not rupture since about two millennia by the joint analysis of geological observations and seismological data acquired during to the 2009 seismic sequence we derive a picture of the complex structural framework of the area comprised between the mavf the paganica fault the 2009 earthquake causative fault and the gran sasso range this sector is affected by a dense array of few km long closely and regularly spaced quaternary normal fault strands that are considered as branches of the mavf northern segment our analysis reveals that these structures are downdip confined by a decollement represented by to the presently inactive thrust sheet above the gran sasso front limiting their seismogenic potential our study highlights the advantage of combining quaternary geological field analysis with high resolution seismological data to fully unravel the structural setting of regions where subsequent tectonic phases took place and where structural interference plays a key role in influencing the seismotectonic context this has also inevitably implications for accurately assessing seismic hazard of such structurally complex regions

radial spreading of buoyant surface plumes in coastal waters shallow buoyant surface plumes in coastal waters sometimes develop by nearly radial spreading from a continuous source such as at a river mouth such plumes often display a ring structure where buoyant water is concentrated between fronts at both the leading and trailing edges of the expanding ring these rings often occur in multiple concentric forms a model of the radial time dependent spreading of a shallow buoyant layer over a motionless deep ambient layer is developed it includes fronts as discontinuities and treats the remainder of the plume flow as inviscid gravitational spreading controlled by nonlinear internal waves calculations by the method of characteristics are presented that show the evolution of a clear ring structure the combination of rapid spreading in the radial geometry together with reflection of internal waves off the frontal boundary at the plume leading edge is shown to be necessary for ring formation a mechanism is suggested for the formation of multiple rings through the shear flow instability inherent in radial spreading

short term vertical velocity field in the apennines italy revealed by geodetic levelling data we estimate current vertical movements along the apennines italy through repeatedly measured high precision levelling routes in order to highlight regional crustal deformation the analysis of a geodetic database with a minimum benchmark density of 0 7 bm km 1943 2003 time period is carried out we evaluate systematic and random error and their propagation along the levelling routes tests on original raw height data have been carried out to define error propagation the computed relative vertical rates stand significantly above error propagation a series of traverses along and across the apennines and a map of relative vertical velocities reveal a geodetic signal characterised by values up to 2 5 3 0 mm a and by wavelengths up to 100 km

anomalous far field geodetic signature related to the 2009 l aquila central italy earthquake the broad availability of geodetic measurements for the mw 6 3 april 6th 2009 l aquila earthquake allowed an unprecedented description of the co and post seismic ground deformations leading to the definition of the paganica fault geometry and kinematics through dinsar we found in a wide area of 20 kilometres on the paganica hangingwall a further displacement up to 7 cm which might have occurred in the earthquake proximity in this study we explore the possibility of the co post and pre seismic alternative scenarios although our data are not sufficient to undoubtedly prove that this signal occurred before the main event this seems to be the most likely hypothesis based on tectonics constraints and image acquisition times the nature of this deformation remains unclear but we speculate that deep fluids played a role these results can drive ad hoc requirements for future space based missions and design of the gps network

changes in static stress on southern california faults after the 1992 landers earthquake the magnitude 7 5 landers earthquake of 28 june 1992 was the largest earthquake to strike california in 40 years the slip that occurs in such an earthquake would be expected to induce large changes in the static stress on neighbouring faults these changes in stress should in turn affect the likelihood of future earthquakes stress changes that load faults towards failure have been cited as the cause of small1 5 moderate6 and large7 earthquakes conversely those that relax neighbouring faults have been related to a decrease in seismicity5 here we use an elastic half space model8 to estimate the stress changes produced by the landers earthquake on selected southern california faults including the san andreas we find that the estimated stress changes are consistent with the triggering of four out of the five aftershocks with magnitude greater than 4 5 and that the largest changes 1 10 bar occurring on part of the san bernardino segment of the san andreas fault may have decreased the time to the next magnitude 8 earthquake by about 14 years

surface deformation in the abruzzi region central italy from multitemporal dinsar analysis summary we investigate the 1992 2000 surface deformation affecting the abruzzi region central italy by exploiting two set of synthetic aperture radar sar data acquired by the ers 1 2 sar sensors from ascending and descending orbits respectively we apply the small baseline subset sbas differential synthetic aperture radar interferometry dinsar technique to the sar data set to estimate the displacement time series and the corresponding velocity maps our dinsar analysis allows us to detect a previously unreported major change in crustal deformation moving from the highest elevation of the central apennines to the adriatic sector that we infer as evidence of a complex tectonic boundary between two adriatic microplates involving a wide interaction zone an extension effect at a rate of about 0 10 10 6 yr 1 is also confirmed by our investigation our findings may have important implications in the seismic hazard assessment within the adriatic region in central italy

coseismic displacements 1992 landers california earthquake the rupture associated with the 1992 landers earthquake ms 7 5 extended along the west edge of a 60 50 km trilateration network that had been surveyed two months before the earthquake and was resurveyed a month after it the coseismic displacement field within the network was calculated from the changes observed in the trilateration network supplemented by the displacements measured at four gps stations and other less timely trilateration measurements stations near the rupture were displaced by as much as 3 m the observed changes are reproduced reasonably well by dislocation modeling in which the landers rupture is represented by 8 vertical fault segments each extending from the surface to 9 km depth two additional segments represent the big bear and eureka peak faults the average modeled right lateral slip on the landers rupture is about 5 m however the residuals for the best fit slip distribution are about four times greater than expected from measurement error given that uncertainty a broad range of slip models furnish acceptable fits to the data the large residuals are attributed to inelastic deformation principally sympathetic slip on numerous unmodeled faults within the fault blocks assumed to be elastic in the model

atmospheric effects in interferometric synthetic aperture radar surface deformation and topographic maps interferogram images derived from repeat pass spaceborne synthetic aperture radar systems exhibit artifacts due to the time and space variations of atmospheric water vapor other tropospheric variations such as pressure and temperature also induce distortions but the effects are smaller in magnitude and more evenly distributed throughout the interferogram than the wet troposphere term spatial and temporal changes of 20 in relative humidity lead to 10 cm errors in deformation products and perhaps 100 m of error in derived topographic maps for those pass pairs with unfavorable baseline geometries in wet regions such as hawaii these are by far the dominant errors in the spaceborne imaging radar c and x band synthetic aperature radar sir c x sar interferometric products the unknown time delay from tropospheric distortion is independent of frequency and thus multiwavelength measurements such as those commonly used to correct radar altimeter and global positioning system gps ionospheric biases cannot be used to rectify the error in the topographic case the errors may be mitigated by choosing interferometric pairs with relatively long baselines as the error amplitude is inversely proportional to the perpendicular component of the interferometer baseline for the sir c x sar hawaii data we found that the best longest baseline pair produced a map supporting 100 m contouring whereas the poorest baseline choice yielded an extremely noisy topographic map even at this coarse contour interval in the case of deformation map errors the result is either independent of baseline parameters or else very nearly so here the only solution is averaging of independent interferograms so in order to create accurate deformation products in wet regions many multiple passes may be required rules for designing optimal data acquisition and processing sequences for interferometric analyses in nondesert parts of the world are 1 to use the longest radar wavelengths possible within ionospheric scintillation and faraday rotation limits 2 for topography maximize interferometer baseline within decorrelation limits and 3 for surface deformation use multiple observations and average the derived products following the above recipe yields accuracies of 10 m for digital elevation models and 1 cm for deformation maps even in very wet regions such as hawaii

contrasting watermass conditions during deposition of the whitby mudstone lower jurassic and kimmeridge clay upper jurassic formations uk abstract the whitby mudstone formation wmf and kimmeridge clay formation kcf are both jurassic organic rich black shale units containing well preserved marine organic matter despite such gross similarities they exhibit opposite trends in 13 c toc versus wt decarbonated total organic carbon toc r 0 76 for wmf and 0 71 for kcf the 13 c toc versus toc trend also varies geographically within both units only the kcf data exhibit a positive correlation between 13 c toc and 15 n org r 0 76 and the presence of aryl isoprenoids probable indicators of photic zone anoxia maturity differences are insufficient to explain such contrasts bulk and compound specific isotopic variations in the kcf are interpreted largely as a reflection of primary productivity during deposition rather than a dominantly diagenetic signal due to incorporation of sulphurised carbohydrate the contrasts between the formations and the geographic variation in coeval shelf sediments are explained by a model stressing the relative positions and stabilities of the chemocline pycnocline nutricline and euphotic zone and the effect these have on productivity co 2 recycling and bacterial floras

evidence for localized active extension in the central apennines italy from global positioning system observations to assess how contemporary crustal extension is accommodated in the central apennines we use a new continuous and survey style global positioning system velocity solution and model the velocity field using a bicubic spline interpolation method the partitioning of contemporary deformation over the 100 km wide central apennines belt reveals a pattern of strain accumulation that largely reflects the spatial distribution of historic and recent seismicity the highest gradients of horizontal velocities are observed across those faults associated with m 6 historical earthquakes dislocation modeling shows that interseismic elastic loading in which creep occurs below the seismogenic upper crust on the downdip extensions of historically active faults reproduces the observed velocity gradients the current resolution level of quaternary fault slip rates estimates hinders the comparison with past deformation patterns and in particular the discrimination between 1 migrating episodes of short term focused activity 2 a distributed pattern of simultaneous deformation on parallel fault systems or 3 long term localization of active extension taking into account geomorphological evidence we propose that the geodetically observed deformation spatially corresponds with a long term localization of strain along the long wavelength 100 km topographic bulge caused by its highest gravitation potential energy relative to surrounding lowlands

an upper bound on the rate of strain in the central apennines italy from triangulation measurements between 1869 and 1963 italy is covered by a first order triangulation network that was established between 1869 and 1908 and re measured in patches between 1936 and 1963 we analyse the measurements made in the central part of italy to form an estimate of the rate of strain in the central apennines we conclude that the rate of strain in this region is too small to detect from the repeated triangulation measurements this result places an upper bound of about 10 7 yr on the strain rate of the central apennines and implies that the maximum rate of extension across the region is no higher than about 3 mm yr

analysis of the deep seated gravitational slope deformations over mt frascare central italy with geomorphological assessment and dinsar approaches abstract a quantitative and innovative dgsd deep gravitational slope deformation assessment method that used integrated remote sensing was tested in the central apennine mountain range italy the movement rate was calculated for selected test areas using the differential sar interferometry small baseline subset sbas technique the selected test areas were previously identified by interpreting both aerial photos and using 32 ers radar images taken between 1993 and 2000 more than 15 cm of cumulative surface displacement occurred across the podalla dgsd along the satellite line of sight los moreover the displacement time series showed non linear deformation rates which included periods of accelerated movement correlated with strong rainfall the high estimated podalla dgsd activity indicates that this type of study should be conducted to monitor the evolution of this phenomenon in addition the dinsar movement rate can be used to improve mapping and identify dgsds in specific landscapes

land subsidence along the ionian coast of se sicily italy detection and analysis via small baseline subset sbas multitemporal differential sar interferometry the paper presents the results of a multi temporal differential interferometric synthetic aperture radar dinsar analysis aiming to identify active surface deformation phenomena in south eastern sicily the study area has been chosen because of its strong seismicity high concentration of industrial and agricultural activities and high density of people living in the coastal area furthermore the morphology lithology and climatic features of this sector of the hyblean foreland are suitable for an interferometric analysis providing a high coherence over the area the small baseline subset sbas multitemporal dinsar technique was used to calculate mean ground velocity maps and displacement time series from a large data set of european remote sensing satellites ers 1 2 images spanning the time period 1992 2000 the reliability of the dinsar results was tested calculating the eastsar and upsar values over two permanent global positioning system gps stations in the area and comparing them with the eastgps and upgps values the residuals between gps and dinsar velocities were 1 and 0 6 mm yr for the up and east components respectively four main subsiding areas previously undetected have been identified corresponding with the towns of augusta siracusa priolo and villasmundo the observed deformation phenomena are located within coastal structural basins filled with pleistocene and holocence deposits except the villasmundo land subsidence which is located on the hyblean plateau the measured deformation rates reach values up to 18 mm yr in augusta 6 mm yr in siracusa 5 mm yr in villasmundo and 4 5 mm yr in priolo the examination of velocity profiles time series and geological data allows us to relate all the detected deformation patterns primarily to groundwater over exploitation a multi dimensional interpolation with kriging was performed to obtain a field subsidence map a first order elastic deformation model was used to simulate the peculiar features of the villasmundo subsidence copyright 2011 john wiley sons ltd

chlorin index a new parameter for organic matter freshness in sediments 1 total chlorins comprising degradation products of chlorophyll have been used recently to reconstruct paleoproductivity from marine sediment cores here we report on a new index the chlorin index ci that proves to be a helpful tool for rapidly estimating organic matter freshness in marine sediments the ci is a ratio between the fluorescence intensity of a sediment extracted with acetone and treated with hydrochloric acid and the original sediment extract it represents the ratio of chlorophyll and its degradation products deposited in the sediments that could still be chemically transformed and those that are inert to chemical attack the ratio is lower in sediments that include freshly deposited phytoplankton material and higher in older more degraded sediments we measured this new parameter on surface sediments and sediments from several short and a long sediment core from different oceanic settings ci values range from 0 2 for chlorophyll a to 0 36 0 56 for fresh material deposited on the shelf off namibia to values around 0 67 in sediments off chile and peru to values up to 0 97 for sediments in a deep core from the northeastern slope of the arabian sea we have compared the ci to rates of bacterial sulfate reduction as a direct measure of organic matter reactivity and to other degradation indices based on amino acid composition we conclude that the ci is a reliable and simple tool for the characterization of organic material freshness in sediments in respect to its degradation state

local and duration magnitude determination for the italian earthquake catalog 1981 2002 this research has been supported in part by project gndt2000 2002 coordinated by a amato and g selvaggi and funded by italian civil protection

the 1994 sefidabeh eastern iran earthquakes revisited new evidence from satellite radar interferometry and carbonate dating about the growth of an active fold above a blind thrust fault in 1994 three shallow earthquakes of mw 6 occurred close together on blind thrusts near sefidabeh in eastern iran in an earlier study of the teleseismic waveforms the geomorphology and the faulting in the epicentral region it was suggested that these earthquakes were associated with the growth of a ridge above a blind thrust fault system whose activity could be detected by its effect on the surface drainage in this study we present a sar interferogram that precisely determines the location and amount of coseismic surface displacements showing that the earthquakes in the sefidabeh sequence probably occurred on en echelon fault segments associated with three stepping ridges we also present u th dates of 100 ka for lake deposits uplifted by the growing ridge from the cumulative dated uplift and knowledge of the surface displacements due to an earthquake sequence we estimate that 120 such events have occurred in the past 100 ka with an average recurrence interval of 830 yr and an average convergence rate of 1 5 mm yr 1 on the sefidabeh thrust each estimate has an uncertainty of a factor of two either way we argue that the sefidabeh fault originally formed by coalescence of many small fault segments and has grown in length at about 2 cm yr 1 in the past 100 ka though the coseismic surface deformation observed in the sar interferogram closely resembles folding the overall topography does not because of inherited topography associated with earlier geological deformation in spite of this the activity of the buried thrust fault can easily be detected by its effect on the surface drainage a significant lesson when interpreting landscapes that are not entirely due to the present day deformation

regional coseismic deformation from the june 28 1992 landers california earthquake results from the mojave gps network the 1992 landers california earthquake sequence and its aftershocks delineate an active part of the eastern california shear zone the surface rupture lies within the mojave desert providing a unique opportunity to characterize far field deformation with a regional global positioning system gps network that was installed and occupied in may 1991 with uncertainties of less than 1 cm on interstation baseline vectors changes in absolute displacement vectors on the decimetre and centimetre level were determined for individual sites providing more samples of the sparsely sampled landers displacement field measured displacements result from secular strain across the mojave desert coseismic elastic recovery and postseismic deformation during the six weeks between the earthquake and the gps experiment secular strain and postseismic displacement are relatively small thus first order modeling of these fields allows calculation and subtraction of their signals leaving a coseismic residual field the gps determined far field coseismic displacements differ significantly from elastic half space models offering new insight on the role of regional scale heterogeneity in crustal structure

active crustal extension in the central apennines italy inferred from gps measurements in the interval 1994 1999 we present the first gps estimate of crustal extension in the central apennines italy through the analysis of the deformation of a sub network of the national gps geodetic network igm95 in the interval 1994 1999 the selected sub network spans the entire active deformation belt perpendicularly to its axis and allows the evaluation of 1 the total extension rate absorbed in this sector of the apennines and 2 the seismogenic potential of the normal faults active in the late pleistocene holocene interval within the network results of this reoccupation are consistent with an extensional strain rate of 0 18 10 6 yr 1 concentrated in an area of about 35 km width giving an average extension rate of 6 2 mm yr across the central apennines the pattern of active deformation suggests active elastic strain accumulation on the westernmost of the two fault systems active in the late pleistocene holocene interval and may also suggest the presence of another active fault system not recognized so far

conditions for interface surfacing upper bounds on extent of ventilation and formation of bottom lenses above topography conditions under which the interface of a rotating layered model can surface and form geostrophic fronts are investigated it is shown how a simple one dimensional reduced gravity model despite its oversimplicity can lead to surfacing criteria and upper bounds on the extent of the ventilation area created by the separation of two newly formed fronts first a no surfacing theorem is established under restrictive conditions then by relaxing conditions one by one wind coast and topography effects are investigated and front properties derived the present search for frontogenetical criteria and ventilation upper bounds which per se is a novel approach to frontal studies is aimed at complementing the existing frontal stability studies by offering additional information on front properties extension to multilayered and two dimensional models is briefly anticipated calling for additional work before more general criteria can be formulated

atmospheric limitations to repeat track radar interferometry in its recent radar imaging mission the shuttle imaging radar satellite sir c devoted three days to repeat track interferometry we have analyzed the data from a test site in the mojave desert of california although good topography 10 m on 21 m postings was obtained most of the error was caused by turbulent water vapor in the lower atmosphere spatial structure of 6 km and all smaller sizes was observed the rms one way time delay was found to be 0 24 cm essentially identical results were obtained at two wavelengths 24 and 5 7 cm

mapping small elevation changes over large areas differential radar interferometry a technique that uses synthetic aperture radar sar images to measure very small 1 cm or less surface motions with good resolution 10 m over large swaths 50 km is presented along with experimental results the method could be used for accurate measurements of many geophysical phenomena including swelling and buckling in fault zones residual displacements from seismic events and prevolcanic swelling the method is based on sar interferometry where two images are made of a scene by simultaneously flying two physically separated antennas then the phases of corresponding pixels are differenced and altitude formation is deduced from some simple computation and image rectification it is also possible to use one antenna flown twice over the same scene then if the second flight exactly duplicates the track of the first an interesting possibility occurs there would be no phase changes between the images at all unless there was a physical change in the scene such as ground swelling that would alter the distance from some resolution element to the antenna since the phase changes all occur at the short carrier wavelength the basic limitation on sensitivity is only the phase noise in the system when the two imaging passes are made from flight tracks that are separated which is the case with the seasat images used here it is no longer possible to distinguish surface changes from the parallax caused by topography however with some additional computation a third image made at some other baseline may be used to remove the topography and leave only the surface changes this method was applied using seasat data to an imaging site in imperial valley california where motion effects were observed that were ascribed to the expansion of water absorbing clays phase change images of this area are shown along with associated ground truth about the presence of water problems with the technique are explored along with a discussion of future experimental possibilities on upcoming sar missions like earth observing system eos earth resources satellite ers 1 sir c and the venus imaging radar magellan

neogene clockwise tectonic rotation of the eastern transverse ranges california suggested by paleomagnetic vectors results from a paleomagnetic study of neogene volcanic rocks situated within and around the pinto basin region of the eastern transverse ranges suggest that the ranges have undergone a clockwise tectonic rotation of 41 4 7 7 since late miocene time both normal and reversed polarities are observed and inclination data indicate no significant flattening the rotation was accompanied by progressive sinistral slip on the several east west trending faults which bound and transect the eastern transverse ranges a computation using the observed amount of cumulative left slip on the east west trending faults of the eastern transverse ranges 50 km and the spacing between the pinto mountain and salton creek faults which bound the region 70 km indicates that 35 of clockwise rotation is required which roughly agrees with the paleomagnetic data removal of the eastern transverse ranges rotation in a reconstruction shows that the distributed dextral shear across the mojave desert region to the north must have been on the order of 100 km since late miocene time from the results of this study we infer that crustal rotation of the eastern transverse ranges began later and is of less magnitude than that of the western transverse ranges

crustal velocity and strain rate fields in italy and surrounding regions new results from the analysis of permanent and non permanent gps networks summary we present a new geodetic velocity solution for italy and the surrounding areas obtained from an analysis of continuous and survey mode global positioning system observations collected between 1991 and 2002 we have combined local regional and global networks into a common reference frame velocity solution providing a new detailed picture of the regional scale deformation field in the central mediterranean our velocity estimates are computed with respect to a new stable eurasian reference frame constraining the kinematics of the greater african eurasian plate boundary system in the study area we provide strain rate values for the main seismotectonic districts which are in good agreement with the seismic deformation inferred from earthquake focal mechanisms the southern tyrrhenian area calabria the apennines the southeastern alps the southern dinarides and the albanides display deformation rates at the order of 20 30 nanostrain yr 1 the corsica sardinia block moves according to eurasian plate motions and there is no indication that the opening of the tyrrhenian is still active the pelagian and sicilian domains are separated by a northwest southeast discontinuity the sicily channel rifted area and marginally significant relative motion between the pelagian plateau and the african plate is also observed the southern tyrrhenian is affected by north south compression and accommodates up to 50 per cent of the africa eurasia relative plate motion whereas the calabrian arc exhibits 2 mm yr 1 northwest southeast extension the observed deformation pattern suggests the presence of a major approximately north south tectonic discontinuity separating the sicilian and calabrian domains an extensional boundary observed along peninsular italy coincides with the distribution of seismogenic faults along the axis of the apennines this boundary separates a tyrrhenian and an adriatic domain with diverging velocities orientated north nnw ward and northeastward respectively the apennines are extending perpendicularly to the chain axis at rates of less than 3 mm yr 1 and only in the outer northern apennines indications of active shortening are observed insignificant deformation is observed in the western po plain and the western alps while the central and eastern alps display north south shortening the eastern adriatic domain is shortening perpendicular to the dinaric front with strain rates increasing from north to south the locus of collision between the aegean balkan system and the adriatic and ionian domains is marked by the kephalonia fault system which accommodates up to 20 1 mm yr 1 of right lateral motion the deformation pattern observed in the peri adriatic domain is well described by a counter clockwise rotation of the adriatic microplate around a pole located in the western alps

inversion of wrapped differential interferometric sar data for fault dislocation modeling the differential synthetic aperture radar interferometry dinsar technique has dramatically boosted the application of remote sensing in many geophysical disciplines particularly tectonics coseismic interferograms have provided in many cases images of earthquakes showing the surface displacement due to the deep fault dislocation aside from being visually appealing such interferograms are of fundamental importance for the analysis by means of appropriate dislocation models of the geometrical and kinematic characteristics of the fault which are also parameters of key interest for earthquake risk management this paper provides a contribution in the general framework of the integration of dislocation models in dinsar processing in particular with reference to coseismic interferograms it proposes a technique that allows the direct inversion of wrapped interferograms for dislocation model analysis this option makes it possible to avoid the critical and error prone processing step of phase unwrapping carried out in the classical analysis of interferometric data examples of inversion of real data relevant to the 1999 athens and izmit earthquakes demonstrate the feasibility and the advantages of this data processing approach

the intrusion of a density current along the coast of a rotating fluid when light rotating fluid spreads over heavier fluid in the vicinity of a vertical wall coast a boundary jet of width forms the leading edge or nose of which propagates with speed along the coast a certain fraction 8 of the boundary transport is not carried by the nose but is deflected backwards detrained and left behind the propagating nose theoretical and experimental results for and are given for a quasi equilibrium constant regime over longer time intervals the laboratory observations suggest that the nose slows down and stagnates whereupon the trailing flow separates from the coast and an intermittent boundary current forms these processes may be relevant to the mixing of oceanic coastal currents and the maintenance of the mean current

on the derivation of coseismic displacement fields using differential radar interferometry the landers earthquake we present a map of the coseismic displacement field resulting from the landers california june 28 1992 earthquake derived using data acquired from an orbiting high resolution radar system we achieve results more accurate than previous space studies and similar in accuracy to those obtained by conventional field survey techniques data from the ers 1 synthetic aperture radar instrument acquired in april july and august 1992 are used to generate a high resolution wide area map of the displacements the data represent the motion in the direction of the radar line of sight to centimeter level precision of each 30 m resolution element in a 113 km by 90 km image our coseismic displacement contour map gives a lobed pattern consistent with theoretical models of the displacement field from the earthquake fine structure observed as displacement tiling in regions several kilometers from the fault appears to be the result of local surface fracturing comparison of these data with global positioning system and electronic distance measurement survey data yield a correlation of 0 96 thus the radar measurements are a means to extend the point measurements acquired by traditional techniques to an area map format the technique we use is 1 more automatic 2 more precise and 3 better validated than previous similar applications of differential radar interferometry since we require only remotely sensed satellite data with no additional requirements for ancillary information the technique is well suited for global seismic monitoring and analysis

absolute far field displacements from the 28 june 1992 landers earthquake sequence on 28 june 1992 the largest earthquake in california in 40 years surface wave magnitude ms 7 5 occurred near the small town of landers in southeastern california and was followed three hours later by the nearby ms 6 5 big bear earthquake1 fortuitously the landers earthquake sequence coincided with the first week of the official three month test period of the international global positioning system and geodynamics service2 igs giving us an unprecendented opportunity to detect absolute pre co and post seismic displacements at a distance of 50 200 km from the main rupture with millimetre level precision mutual and independent confirmation of some of our geodetic results are demonstrated by bock et al in this issue3 for the landers earthquake the observed displacements indicate that the depth of the bottom of the rupture is shallower towards the northern end displacements were dominantly symmetric and the rupture extended further south on the johnson valley fault than has been mapped on the basis of surface ground offsets the combined geodetic moment for the landers and big bear earthquakes 1 1 1020 n m 1 agrees well with teleseismic estimates

composition and diagenesis of neutral carbohydrates in sediments of the baltic north sea transition abstract the distribution and composition of neutral carbohydrates in the solid phase and porewater and their role in carbon cycling were investigated in contrasting marine sediments of the baltic north sea region depth invariant profiles of particulate carbohydrates pcho and low pcho yields pcho organic carbon indicated that a small inert carbohydrate fraction deposits on the sediment at the deeper stations in the northern kattegat and skagerrak compared to the shallower stations further south this was supported by long term sediment incubations in which the pcho concentrations remained unchanged during 480 days revealing that neutral carbohydrates play a minor role in carbon mineralization at the deeper sites in contrast the reactivity of pcho was high first order rate constant of 3 2 yr 1 at one shallow site in the belt sea monosaccharide spectra were uniform with sediment depth and between sites with the exception of the shallowest site in the middle of kattegat where glucose dominated the polymers at the surface this was likely due to benthic diatoms addition of fresh algae to surface sediment from the deeper sites resulted in a preferential mineralization of particulate glucose polymers the addition of algae also resulted in an initial pulse of glucose in the porewater pools of total hydrolyzable carbohydrates thcho indicating a faster hydrolysis of glucose polymers in the particulate phase than the subsequent hydrolysis and bacterial consumption of oligo and polymers of glucose in the porewater this study shows that some carbohydrates such as glucose polymers are selectively utilized by heterotrophic bacteria during the settling of organic particles through the water column and a relatively inert fraction arrives to the sediments where much of it escapes mineralization and becomes permanently buried in shallow coastal environments where the degradation in the water column is less extensive and where benthic algae may represent a local carbohydrate source neutral carbohydrates appear to be more important in organic matter mineralization

active tectonics of the adriatic region from gps and earthquake slip vectors 1 to investigate the kinematics of the adriatic region we integrate continuous and episodic gps measurements with mw 4 5 earthquake slip vectors selected from the regional centroid moment tensor catalogue coherent motion of gps sites in the po valley in apulia and in the hyblean plateau allows us to estimate geodetically constrained angular velocities for these regions the predictions of the gps inferred angular velocities are compared with the earthquake slip vectors showing that the seismically expressed deformation at the microplate boundaries is consistent with the observed geodetic motion the remarkable consistency between geodetic seismological and geological evidence of active tectonics suggests that active deformation in the central adriatic is controlled by the relative motion between the adria and apulia microplates the microplates angular rotation rates are then compared with the rotation rates calculated with a simple block model supporting the hypotheses 1 that apulia forms a single microplate with the ionian sea and possibly with the hyblean region and 2 that adria and apulia rotate in such a way as to accommodate the eurasia nubia relative motion we suggest that the present day microplate configuration follows a recent fragmentation of the adriatic promontory that during the neogene rigidly transferred the africa motion to the orogenic belts that now surround the adriatic region

co seismic displacements of the 1992 landers earthquake sequence we present co seismic displacement vectors derived from global positioning system gps measurements of 92 stations in southern california these gps results are combined with five well determined gps displacement vectors from continuously tracking stations of the permanent gps geodetic array as well as line length changes from usgs geodolite and two color laser trilateration observations to determine a self consistent set of geodetic data for the earthquake these combined displacements are modeled by an elastic dislocation representation of the primary fault rupture planes on average the model residuals are about twice the estimated measurement errors

current strain regime in the western alps from continuous global positioning system measurements 1996 2001 four to six years of continuous measurements at 10 permanent global positioning system sites in the western alps show horizontal residual velocities of 2 mm yr with respect to stable europe uncertainties range from 0 3 to 1 4 mm yr these velocities and the associated strain rate field indicate that the central part of the range is currently dominated by east west extension whereas the southern part shows north south to northwest southeast compression the geodetic and seismotectonic data are consistent with a model where strain is essentially controlled by the counterclockwise rotation of the adriatic microplate with respect to eurasia this rotation together with the arcuate shape of the contact between the adriatic microplate and the alps induces dextral shear kinematic boundary conditions across the western alps with an additional divergence component in their central part and in switzerland and a convergence component in their southern part

constraints on the seismotectonics of the central mediterranean from very long baseline interferometry summary very long baseline interferometry vlbi determined site velocities from seven stations in western europe reveal a stable continental platform north of the alps deformations between sweden germany and spain can not exceed 2 mm yr south of the alps significant motions are occurring with respect to stable europe two sites east of the apennine mountains on peninsular italy have north easttrending velocities which increase from 2 mm yr l in the north at medicina to 6 mm yr l in the south at matera in contrast the vlbi site in the south eastern corner of sicily is moving 7 mm yr i to the north north west these velocities are largely explained if southern sicily is attached to a north westerly moving african plate and the eastern portion of the italian peninsula forms part of a hypothesized adriatic sea crustal block which is rotating counter clockwise with respect to europe about a pole near the alps such an explanation is consistent with the styles of the larger historical earthquakes of the region which show ne sw extension across the apennines north south convergence across the alps and ne sw compression in coastal yugoslavia the adria plate model generates 1 5 2 2 x 10l8 nm yr l of potential earthquake moment along the northern and central apennines historical records suggest that 30 60 per cent of this moment is released seismically based on a direct strain rate measurement recurrence intervals for italian earthquakes south of medicina are estimated to be 12 46 yr for m6 5 quakes and 35 143 years for m7 0 quakes

the importance of ultrafine particles as a control on the distribution of organic carbon in washington margin and cascadia basin sediments thecombinedeffectsofhydrodynamicparticlesorting sorptiveprotectionandoxygenexposuretime oet onthedistributionof organic carbon in continental margin surface sediments was investigated in detail using the splitt fractionation split flow thin cell technique along a well characterized seven station transect from the inner washington shelf to the central cascadia basin the new data highlight the significance of virtually buoyant ultrafine particles size b38 m and settling velocity b1 m d for organic carbon oc deposition fortheentiresurfacesedimenttransect thisultrafineparticlefractionhosted45 85 ofthebulkoc withan increasing contribution further away from the coast in this fraction oc to mineral surface area oc sa ratios generally ranged from 0 5 to 1 1 mg oc m 2 which is typical of most continental margin sediments underlining the key role that ultrafine particles undertake in oc sorption an exception was the lower oc sa ratios in the b38 m fraction of cascadia basin sediments which coincided with an order of magnitude increase in mn oxyhydroxides abundance an inverse relationship between oc sa and opal was attributed to a diluting effect of opal on the sa and a lack of association between opal and oc finally two distinct regimes with different preservation controls were revealed along the shelf slope basin transect finally the shelf sediments do not follow the relationshipbetweenoetandoc saobservedintheslopeandbasinsites presumablyduetorapidsedimentationclosertothecoast