the 1986 kalamata south peloponnesus earthquake detailed study of a normal fault evidences for east west extension in the hellenic arc tectonic and seismological data collected in the field following the september 13 1986 kalamata earthquake south peloponnesus are presented and analyzed to discuss the earthquake rupture process and the regional tectonics the event occurred on the kalamata normal fault whose trace was mapped with spot images and topographic and field observations this fault is part of an approximately nnw sse en echelon system cutting through the hellenic nappes the fault striking n15 e on the average with a dip of about 50 has a minimum cumulated quaternary throw of the order of 1 km the measured coseismic slip is 6 18 cm over a length of 6 km the main shock focal mechanism obtained from long period waveform modeling strike 201 10 20 dip 45 5 rake 283 10 25 represents almost pure east west extension and is in good agreement with tectonic observations the centroid depth is constrained to 5 3 km and the seismic moment to 7 0 2 5 1017 n m over 700 aftershocks located by a 16 station network installed after the earthquake for a period of 2 weeks define two clusters separated by a gap of aftershock activity from the surface to a depth of about 10 km the main cluster to the south defines a 45 west dipping plane which lies on the downward extension of the fault mapped at the surface focal mechanisms of aftershocks on this fault plane are homogeneous and represent e w extension as the main shock in contrast the majority of focal mechanisms in the uppermost part of the foot wall show more or less e w compression probably corresponding to postseismic stress release the northern cluster of aftershocks is very dense and located away from the surface rupture within a relay zone between the kalamata and the next en echelon faults to the nw the thouria faults there focal mechanisms represent extension from about n115 to n70 and n20 corresponding mostly to fault reactivation in an area where nonrigid deformations prevail the main shock probably initiated in this relay zone 3 4 s before the rupture front reached the main fault plane and released most of the energy there the rupture presumably propagating southward the focal mechanism of the kalamata earthquake and that of the april 27 1965 earthquake located to the northwest of crete as well as the regional active normal fault pattern imply that e w extension oblique to the hellenic arc is presently the dominant tectonic regime e w stretching occurs partly on reactivated nw se faults parallel to the hellenic structures but mostly on newly formed n s normal faults across those structures the latter faults are responsible for the apparent segmentation of the hellenic belt from southern peloponnesus to crete the existence of active e w extension in this region implies a recent change in the tectonic regime and consequently a change in boundary conditions at the subduction zone probably in response to the incoming margin of africa

the hellenic subduction beneath the peloponnesus first results of a microearthquake study abstract a preliminary examination of the 1070 earthquake locations determined from 6 weeks of recording in 1986 by 46 stations show that the seismicity is spread over a wide area of the peloponnesus and the western hellenic arc and throughout the whole crust no clear individual faults can be identified from the seismicity but clusters of activity are observed in some places seismicity is concentrated above 40 km and deeper earthquakes were not numerous only 28 of the 466 events with uncertainties in depth less than 5 km occurred deeper than 40 km seismicity deeper than 30 km defines a flat zone at a depth between 40 km and 70 km starting from the trench to about 200 km towards the northeast further northeast the dip of the seismic zone abruptly changes to 45 fault plane solutions for the deeper events generally indicate t axes plunging northeast within the subducted slab therefore we interpret the seismicity deeper than 30 km as due to the superposition of two different causes 1 the steep zone is due to the subduction of the african litospheric plate beneath the aegean and 2 the shallow flat zone located between the trench and the argolide is partly due to the loading of the overriding aegean plate which is deforming above the african plate

drainage basin sensitivity to tectonic and climatic forcing implications of a stochastic model for the role of entrainment and erosion thresholds long term average rates of channel erosion and sediment transport depend on the frequency magnitude characteristics of ood ows that exceed an erosion threshold using a poisson model for rainfall and runoff analytical solutions are developed for average rates of stream incision and sediment transport in the presence of such a threshold solutions are derived and numerically tested for three erosion transport formulas the howard kerby shear stress incision model the bridge dominic sediment transport model and a generic shear stress sediment transport model results imply that non linearity resulting from threshold effects can have a rst order impact on topography and patterns of dynamic response to tectonic and climate forcing this non linearity becomes signi cant when fewer than about half of ood events are capable of detaching rock or sediment predicted morphology and uplift gradient scaling is more closely consistent with observations and laboratory experiments than conventional slope linear or shear linear erosion laws these results imply that particle detachment thresholds are not details that can be conveniently ignored in long term landscape evolution models copyright 2004 john wiley sons ltd

the sparta fault southern greece from segmentation and tectonic geomorphology to seismic hazard mapping and time dependent probabilities the sparta fault system is a major structure approximately 64 km long that bounds the eastern flank of the taygetos mountain front 2407 m and shapes the present day sparta basin it was activated in 464 b c devastating the city of sparta this fault is examined and described in terms of its geometry segmentation drainage pattern and post glacial throw emphasising how these parameters vary along strike qualitative analysis of long profile catchments shows a significant difference in longitudinal convexity between the central and both the south and north parts of the fault system leading to the conclusion of varying uplift rate along strike catchments are sensitive in differential uplift as it is observed by the calculated differences of the steepness index ksn between the outer ksn 83 and central parts 121 ksn 138 of the sparta fault along strike the fault system based on fault throw rates and the bedrock geology a seismic hazard map has been constructed that extracts a locality specific long term earthquake recurrence record based on this map the town of sparta would experience a destructive event similar to that in 464 b c approximately every 1792 458 years since no other major earthquake m 7 0 has been generated by this system since 464 b c a future event could be imminent as a result not only time independent but also time dependent probabilities which incorporate the concept of the seismic cycle have been calculated for the town of sparta showing a considerably higher time dependent probability of 3 0 1 5 over the next 30 years compared to the time independent probability of 1 66 half of the hanging wall area of the sparta fault can experience intensities ix but belongs to the lowest category of seismic risk of the national seismic building code on view of these relatively high calculated probabilities a reassessment of the building code might be necessary

active fault geometry and kinematics in parnitha mountain attica greece abstract the parnitha mountain range lies between two quaternary rift systems in central greece the gulf of corinth rift and the gulf of evia rift we suggest that the range was formed by footwall uplift on active normal faults striking wnw ese and ne sw we investigated the scarp appearance geometry and slip rates of three normal faults bounding this mountain range by field mapping at 1 5000 scale active faults studied include the 8 5 km long fili fault the 4 7 km long maliza fault and the 4 km long thrakomakedones fault we calculated comparable mean slip rates for all mapped faults fili 0 18 mm yr avlon 0 2 mm yr thrakomakedones 0 24 mm yr however we suggest that the wnw ese structures are more active during the late quaternary because of abundant field evidence of recent movements along slip surfaces fresh basal stripes and slickenlines in addition stress axes analysis shows a n7 e n25 e nne ssw oriented extensional stress field which is compatible with the focal mechanism of the athens 1999 earthquake the fault slip data from the parnitha faults show orientations similar to other low strain areas in central greece such as the gulf of evia rift to the north our slip rate estimates may explain the low recurrence of large earthquakes in attica as opposed to high slip rate areas in central greece such as the neighbouring gulf of corinth

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

slickenline orientations as a record of fault rock rheology abstract contact of geometric asperities across rough faults causes perturbations to the shear traction resolved on a fault surface that could potentially deflect the local slip direction slickenlines which record the relative displacement of opposing sides of a fault may therefore be sensitive to fault surface geometry to investigate the relationship between fault geometry shear traction and slip we use ground based lidar to measure the orientations of slickenlines defined by centimeter amplitude corrugations on three fault surfaces slickenline rakes measured in the mean plane of each fault rarely vary by more than a few degrees deviations from the mean rake do not correlate with the fault surface topography at scales up to a few meters but a weak correlation may be present at larger scales slip directions are therefore insensitive to any shear traction perturbations from the contact of geometric asperities at small scales this observation is consistent with scale dependent deformation we show that the roughness of fault surfaces implies that short wavelength asperities fail inelastically because of flattening during fault slip a crossover to elastic deformation occurs at lengths of 10 2 to 10 0 m which defines the minimum dimension of a strength asperity that influences the displacement field the roughness at the crossover length scale corresponds to the typical thickness of fault rocks in the fault core suggesting that fault rock thickness is related to the crossover length scale the data requires that multiple processes combine to produce the fault surface geometry we reconcile the variety of processes with the consistent surface roughness scaling by noting that all of the processes are governed in different ways by the elastic limit of rock

east west extension and holocene normal fault scarps in the hellenic arc examination of surface fault traces with spot images and in the field corroborates the inference that the active tectonics of southern peloponnesus and crete are dominated by approximately north south normal faulting and approximately east west extension the heights of holocene normal fault scarps yield first order regional estimates of fault slip rates between 0 1 and 2 3 mm yr most of the surface scarps probably ruptured during past earthquakes such as that which destroyed sparta in 464 b c on the sparta fault the holocene average slip rate and the recurrence time of large earthquakes may be 1 mm yr and 3000 yr respectively the regional pattern of quaternary faulting suggests that the east west extension near the hellenic subduction zone is fast about 5 10 m y the change from north south to east west extension in the late pliocene 2 4 ma implies that the aegean is starting to collide with the northern margin of africa

surface fault traces fault plane solution and spatial distribution of the aftershocks of the september 13 1986 earthquake of kalamata southern greece a shallow earthquake ofms 6 2 occurred in the southern part of the peloponnesus 12 km north of the port of the city of kalamata which caused considerable damage the fault plane solution of the main shock geological data and field observations as well as the distribution of foci of aftershocks indicate that the seismic fault is a listric normal one trending nne ssw and dipping to wnw the surface ruptures caused by the earthquake coincide with the trace of a neotectonic fault which is located 2 3 km east of the city of kalamata and which is related to the formation of messiniakos gulf during the pliocene quaternary tectonics field observations indicate that the earthquake is due to the reactivation of the same fault

fault slip directions in central and southern greece measured from striated and corrugated fault planes comparison with focal mechanism and geodetic data fault slip directions recorded by outcropping striated and corrugated fault planes in central and southern greece have been measured for comparison with extension directions derived from focal mechanism and global positioning system gps data for the last 100 years to test how far back in time velocity fields and deformation dynamics derived from the latter data sets can be extrapolated the fault slip data have been collected from the basin bounding faults to plio pleistocene to recent extensional basins and include data from arrays of footwall faults formed during the early stages of fault growth we show that the orientation of the inferred stress field varies along faults and earthquake ruptures so we use only slip directions from the centers of faults where dip slip motion occurs to constrain regionally significant extension directions the fault slip directions for the peloponnese and gulfs of evia and corinth are statistically different at the 99 confidence level but statistically the same as those implied by earthquake focal mechanisms for each region at the 99 confidence level they are also qualitatively similar to the principal strain axes derived from gps studies extension directions derived from fault slip data are 043 047 for the southern peloponnese 353 for the gulf of corinth and 015 014 for the gulf of evia extension on active normal faults in the two latter areas appears to grade into strike slip along the north anatolian fault through a gradual change in fault slip directions and fault strikes to reconcile the above with 5 myr 1 clockwise rotations suggested for the area we suggest that the faults considered formed during a single phase of extension the deformation and formation of the normal fault systems examined must have been sufficiently rapid and recent for rotations about vertical axes to have been unable to disperse the fault slip directions from the extension directions implied by focal mechanisms and gps data thus in central and southern greece the velocity fields derived from focal mechanism and gps data may help explain the dynamics of the deformation over longer time periods than the 100 years over which they were measured this may include the entire deformation history of the fault systems considered a time period that may exceed 1 2 myr

slip vector analysis with high resolution t lidar scanning abstract a palaeostress analysis of an active bedrock normal fault scarp based on kinematic indicators is reconstructed using terrestrial laser scanning tls for this purpose three key elements are necessary for a defined region i the orientation of the fault plane ii the orientation of the slickenside lineation or other kinematic indicators and iii the sense of motion of the hanging wall the paper specifies a workflow in order to obtain stress data from point cloud data using terrestrial laser scanning tls in an active tectonic environment the entire analysis was performed on a continuous limestone bedrock normal fault scarp on the island of crete greece at four different locations along the wnw ese striking spili fault at each location we collected data with the terrestrial light detection and ranging system t lidar we then validated the calculated three dimensional stress results at three of the locations by comparison with conventional methods using data obtained manually with a compass clinometer numerous kinematic indicators for normal faulting were discovered on the fault plane surface using t lidar data when comparing all reconstructed stress data obtained from t lidar to that obtained through manual compass measurements the degree of fault plane orientation divergence is 005 03 for dip direction and dip the degree of slickenside lineation divergence is 003 03 for dip direction and dip therefore the percentage threshold error of the individual vector angle at each investigation site is lower than 3 for the dip direction and dip for planes and lower than 6 for the strike the maximum mean variation of the complete calculated stress tensors is 005 03

late quaternary history of the chemehuevi mountain piedmont mojave desert deciphered using 10be and 26al we used the cosmogenic nuclides 10 be and 26 al as cosmic ray dosim eters to track sediment movement across the incised chemehuevi mountain piedmont surface the piedmont extends 12 km from highland source basins to an ephemeral wash at the toe of the piedmont nuclide activity in sediment from steep source basins and from the bedrock pediment allows us to estimate rates of sediment generation and thus the rate at which sediment is supplied to the piedmont from weathering rock analysis of amalgamated sediment samples collected along 4 km long transects spaced at 1 km intervals from the mountain front provide context for understanding nuclide activity in sediment samples collected from two soil pits and demonstrate that sediment steadily moves down the channel network samples from the two soil pits allow for estimates of sediment deposition rates and thus further illuminate piedmont history model results suggest that the chemehuevi mountains are eroding about 40 mm ky 1 whereas the mountain proximal bedrock pediment and the interpiedmont saw tooth range are eroding more slowly 10 to 21 mm ky 1 and 9 5 mm ky 1 respectively cosmogenic nuclide profiles in two soil pits suggest a complex history of deposition at rates between 19 to 39 mm ky 1 and stability over the past 60 ky a change in process from sediment deposition to sediment transport occurred distally on the piedmont approximately 8 ky ago while the mid piedmont piedmont surface has been stable since the mid holocene the incised chemehuevi mountain piedmont is changing at rates similar to planar and uniformly active piedmonts such as those adjacent to the iron and granite mountains all three piedmonts have average sediment grain velocities of decimeters per year long term source basin erosion rates between 35 to 40 mm ky depositional hiatuses around the pleistocene holocene climatic transition from moister to drier conditions and pleistocene deposition rates of 18 to 39 mm ky such similarity in piedmont behavior despite clear differences in morphology and appearance might suggest large scale geologic and climatic controls on the generation transport and deposition of sediment in the mojave desert

gravel dispersion on a granite pediment east mojave desert california a short term look at erosional processes hypotheses about the influence of surface shape landscape unit and vegetation cover on gravel dispersion were tested on a shallowly dissected portion of a low sloping granite pediment in the east mojave desert of california painted gravels 2 to 20 mm diameter were placed at 117 nodes on a 6m 3m grid gravel movements were recorded after 9 7 cm of precipitation over a four month period vectors indicating the magnitude and direction of gravel movement were longest for summits 24 cm 34 nodes observed and shortest for backslopes 14 cm 27 nodes observed gravels beneath shrub canopies were protected significantly from rainsplash transport to describe dispersion symmetry eccentricity values were calculated using a ratio of variances of major and minor axes of an ellipse mean eccentricity values ranged from about 3 to 250 with dispersion on summits being the most symmetrical and dispersion in washes being the most elongated erosion is the most important soil and pediment modifying process at upper elevations of the granite cove pediment which is cut off from sediment additions because of washes incised at the base of the mountain front copyright 1999 john wiley sons ltd

a hectare of fresh striations on the arkitsa fault central greece abstract some large new exposures of active normal faults in central greece reveal polished surfaces that could represent as many as 50 increments of co seismic slip the slip surfaces are nearly two dimensional with the slip vector aligned down the axes of corrugations and undulations however small but regular changes in slip vector between top and bottom of the exposure and a regular asymmetry of the polishing on corrugations may be related to block rotations about a vertical axis and show how the slip vector changes with time

partitioned postseismic deformation associated with the 2009 mw 6 3 l aquila earthquake surface rupture measured using a terrestrial laser scanner using 3d terrestrial laser scan tls technology we have recorded postseismic deformation on and adjacent to the surface rupture formed during the 6th april 2009 l aquila normal faulting earthquake mw 6 3 using surface modeling techniques and repeated surveys 8 124 days after the earthquake we have produced a 4d dataset of postseismic deformation across a 3 65 m area at high horizontal spatial resolution we detected millimetre scale movements partitioned between discrete surface rupture slip and development of a hangingwall syncline over 10 s of meters we interpret the results as the signal of shallow afterslip in the fault zone we find 52 of the total postseismic hangingwall vertical motion occurs as deformation within 30 m of the surface rupture the total postseismic vertical motions are approximately 50 that of the coseismic we highlight the importance of quantifying partitioned postseismic contributions when applying empirical slip magnitude datasets to infer palaeoearthquake magnitudes

three dimensional model of hellenic arc deformation and origin of the cretan uplift 1 the hellenic arc of greece is the most seismically active part of europe but little is know about its mechanics we modeled deformation along the arc using a finite element model the model was intended to capture large scale 3 d structure of nubian plate subduction beneath the aegean block and its deformational consequences the shape of the interface was developed using mapped traces at the surface and earthquake hypocenters at depth model block motions were constrained by recent compilations of gps velocity vectors we simulated a 10 ka period of convergence between nubia and the aegean and calculated the strain field in the overriding plate as well as the spatial distribution and orientation of differential stress 1 3 from these calculations we derived testable quantities such as the expected seismic moment rate on the interplate contact uplift pattern and distribution of strain modes our relatively simple model broadly reproduced observed uplift patterns earthquake activity and loci of extension and contraction the model showed a localization of uplift near the island of crete where the fastest aegean uplift rates are well documented comparison of calculated expected seismic moment and observed earthquake catalogs implies a nearly fully coupled interplate contact on the basis of our modeling results we suggest that south aegean deformation is driven primarily by the fast moving 33 mm a 1 aegean upper plate overriding a nearly stalled 5 mm a 1 nubian lower plate this tectonic setting thus more closely resembles a continental thrust than it does a typical oceanic subduction zone

crustal motion and deformation in greece from a decade of gps measurements 1993 2003 abstract the hellenic plate boundary region located in the collision zone between the nubian arabian and eurasian lithospheric plates is one of the seismo tectonically most active areas of europe during the last 15 years gps measurements have been used to determine the crustal motion in the area of greece with the aim to better understand the geodynamical processes of this region an extended reoccupation network covering whole greece has been measured periodically in numerous gps campaigns since the late eighties and a continuous gps network has been operated in the region of the ionian sea since 1995 in this paper we present a new detailed high quality solution of continuous and campaign type measurements acquired between 1993 and 2003 during the gps processing a special effort was made to obtain consistent results with highest possible accuracies and reliabilities data of 54 mainly european igs and euref sites were included in the gps processing in order to obtain results which are internally consistent with the european kinematic field and order to allow for a regional interpretation after an overview of the results of the igs euref sites the results from more than 80 stations in greece are presented in terms of velocities time series trajectories and strain rates previous geodetic geological and seismological findings are generally confirmed and substantially refined new important results include the observation of deformation zones to the north and to the south of the north aegean trough and in the west hellenic arc region arc parallel extension of about 19 mm yr along the hellenic arc and compression between the ionian islands and the greek mainland due to continuous long term observations of 4 8 years it was possible to extract height changes from the gps time series in greece we observe a differential subsidence of the order of 2 mm yr between the northern and central ionian islands across the kefalonia fault zone the differential subsidence of the central ionian islands with respect to the northwestern greek mainland amounts to 4 mm yr

euclidean and fractal models for the description of rock surface roughness accurate description of the topography of rock surfaces is essential because surface roughness affects frictional strength the flow of fluids in joints and fractures the seismic behavior of faults and the formation of gouge and breccia in fault zones real rock surfaces can be described using self similar and self affine fractal models of surface roughness if a surface is self similar a small portion of the surface when magnified isotropically will appear statistically identical to the entire surface if a surface is self affine a magnified portion of the surface will only appear statistically identical to the entire surface if different magnifications are used for the directions parallel and perpendicular to the surface at least two parameters are required to describe a fractal model one parameter typically describes how roughness changes with scale while the other specifies the variance or surface slope at a reference scale the divider method and the spectral method are in common use to determine the best fit fractal model from surface profile data power spectra from self similar surfaces have slopes of 3 on log log plots of power spectral density versus spatial frequency while spectra from self affine surfaces have slopes other than 3 power spectra can be interpreted with greater facility if dimensionless amplitude to wavelength ratios are contoured on plots of power spectral density versus frequency the topography of many natural rock surfaces including both fractures and faults is approximately self similar within the 6 5 order of magnitude wide wavelength band of 10 m to 40 m within smaller wavelength bands natural rock surfaces may exhibit self affine behavior

reprint of bedrock fault scarp history insight from t lidar backscatter behaviour and analysis of structure changes abstract this paper provides a research approach and develops a methodology that helps natural weathered bedrock fault scarps to be understood in terms of their structural changes and backscatter behaviour when using terrestrial laser scanning t lidar we tested our approach on the pisia fault in greece that ruptured during the 1981 alkyonides earthquake sequence in corinth gulf the method describes how to correlate fault geometry and structural variations with the backscatter signal of t lidar data from naturally exhumed bedrock fault scarps using this method we are able to reconstruct the past slip history we used t lidar for the analysis of the monochromatic laser beam s backscattered signal to define unsupervised classes of unknown objects on fault surface seven classes were created based on the dendrogram technique using the maximum likelihood method these were used to determine their spatial distribution throughout the scarp height and to calculate the terrain ruggedness index tri in the defined classes the combination of these results shows that i the ruggedness increases with the scarp height and ii the ruggedness and backscattering describe different fault plane conditions we found evidence for past earthquakes on the pisia fault at our study site with average displacements in the range of 30 60 cm with corresponding magnitudes of 6 4 6 6 0 1 ms these results help to reconstruct the recent fault history and potential palaeo events and can also be used i to detect appropriate sample sites on the fault plane for absolute dating and ii as an independent constraint on tracing slip events assisting absolute dating techniques this method can significantly reduce the sampling requirements and costs of cosmogenic absolute dating techniques overall it might be a valuable tool for extracting data regarding the faulting history and slip events for defining seismic hazard parameters

coseismic and postseismic subsurface displacements and strains for a dip slip normal fault in a three layer elastic gravitational medium a three layer elastic gravitational fault displacement model has been developed using elastic dislocation and employed to examine the effects of rigidity layering gravity and stress relaxation on surface and subsurface displacements fields for a dip slip normal fault within our three layer model layer 1 represents the upper crust layer 2 the lower crust and layer 3 the upper mantle the fault is embedded in the upper crust horizontal as well as vertical displacement components have been determined displacement field changes due to postseismic stress relaxation have been calculated using both the correspondence principle and relaxed rigidity moduli and results are in close agreement the relaxed rigidity method provides an accurate and computationally efficient method of examining postseismic relaxation postseismic relaxation within the lower two layers only gives surface uplift increasing footwall uplift and decreasing hangingwall subsidence and also increases the wavelength of surface vertical displacement postseismic stress relaxation within all three layers i e uniform half space produces a shorter wavelength of surface vertical deformation with respect to the coseismic response moho topography created during coseismic deformation is initially amplified during postseismic relaxation the relaxed moho topography is dependent on the strength of the upper crust as well as the strength of the lower crust and mantle gravity has a significant influence on displacements only at the postseismic stage when the effective rigidity of the lower layers is small coseismic and postseismic normal strains associated with dip slip normal faulting have been examined for a large normal basement fault intersecting the free surface the coseismic horizontal surface strain perpendicular to fault strike is compressive adjacent to the fault and in the footwall and tensile in the hangingwall away from the fault coseismic stress redistribution may generate significant tensile brittle failure of the upper crust adjacent to large basement faults

constraints on the dynamics and spatio temporal evolution of the 2011 oichalia seismic swarm sw peloponnesus greece abstract in this paper we present a detailed study of a shallow seismic swarm which took place in the area of oichalia sw peloponnesus between august and december 2011 the seismic crisis started on 14 8 2011 with an mw 4 8 earthquake and was followed by more than 1600 events several of which having magnitude over 4 0 the activity was recorded by local temporary and regional permanent seismic stations thousands of records were collected and routinely analyzed p and s wave arrival times were manually picked and incorporated in the hypoinverse algorithm together with a new optimum local velocity model hypocentral solutions were improved by applying a double difference method focal mechanisms show that the activated fault zone is dominated by dip slip normal faulting trending nnw sse with the average t axes orientation being n70 e consistent with regional tectonics we have investigated towards stress triggering and fluid diffusion by employing coulomb stress transfer spatio temporal and frequency magnitude distribution fmd analyses the negligible coulomb stress transfer and seismicity rate changes that were calculated imply for a stress deficit in the broader study area hence an external triggering mechanism is required to justify the observed pattern the b values increase towards the sse compatible with the similarly directed migration of seismicity showed that the oichalia swarm could possibly be adapted to an epidemic type aftershock sequence model etas fluid diffusion is reflected in the spatio temporal hypocenter migration clustering analysis combined with the temporal distribution of b values has shown that the swarm evolved in three major phases the first two being initiated by major events which were probably triggered externally due to fluid injection that brought the seismogenic volume into a critical state likely followed by afterslip the last phase signified a relaxation period with dispersed seismicity throughout the area and the b values gently diminishing towards unity

non planarity scale dependent roughness and kinematic properties of the pidima active normal fault scarp messinia greece using high resolution terrestrial lidar data abstract terrestrial lidar tls photogrammetric and field data were collected during the years 2014 2015 and 2017 at a 20 m long limestone scarp locality along the n s striking 70 west dipping active pidima fault messinia sw peloponnese greece this locality presents an artificially exhumed portion of an active fault plane thus providing a unique opportunity to study kinematics and limestone scarp morphology including its curvature and roughness the survey of 2015 offered a high density point cloud of the fault scarp with 6 mm working resolution creating a very close to real life representation 3d model we found that scarp geometry is non planar with increasing convexity up dip and increasing northwesterly dip directions from north towards south along strike non planarity is also recorded from the morphological data along strike with the appearance of several slip parallel troughs and ridges with a mean distance half wavelength of 0 75 m the fault plane roughness absolute values is scale dependent the roughness configuration attains a slip parallel pattern for observation scales above 1 cm at observations scales less than 1 cm a slip normal pattern is weakly visible the obtained tls results agree with field data manual compass measurements and macroscopic observations we infer an earthquake magnitude of 6 2 0 2 for the last event along the pidima fault based on the measured thickness of the smooth stripe that was imaged by t lidar along the non exhumed surface of the scarp

terrestrial laser scanning in geology data acquisition processing and accuracy considerations terrestrial laser scanning or lidar is a recent innovation in spatial information data acquisition which allows geological outcrops to be digitally captured with unprecedented resolution and accuracy with point precisions and spacing of the order of a few centimetres an enhanced quantitative element can now be added to geological fieldwork and analysis opening up new lines of investigation at a variety of scales in all areas of field based geology integration with metric imagery allows 3d photorealistic models to be created for interpretation visualization and education however gaining meaningful results from lidar scans requires more than simply acquiring raw point data surveys require planning and typically a large amount of post processing time the contribution of this paper is to provide a more detailed insight into the technology data collection and utilization techniques than is currently available the paper focuses on the workflow for using lidar data from the choice of field area and survey planning to acquiring and processing data and finally extracting geologically useful data because manufacturer specifications for point precision are often optimistic when applied to real world outcrops the error sources associated with lidar data and the implications of them propagating through the processing chain are also discussed

a rough guide to limestone fault scarps abstract the surface roughness of limestone fault scarps in central greece is examined with the aim of relating variations in rock weathering to palaeoseismic activity the study employs a micro roughness meter mrm and a carpenter s profile gauge to collect field measurements of scarp roughness presenting the results in terms of roughness indices which permit comparison between different height levels of a scarp the study confirms the increasing degradation of scarps with height thereby inferring the time dependent evolution of fault scarp roughness in addition roughness indices are found to discriminate between fault surfaces exposed during the 1981 corinth earthquakes and those emergent prior to this event

mounds associated with shrubs in aridic soils of northeastern patagonia characteristics and probable genesis abstract studies of mounds associated with shrub clumps in northeastern patagonia indicate that these forms have an average major diameter of 355 cm and an average height of 41 cm mound cover and density are 40 and 450 mounds ha respectively mound and intermound soils present a similar textural composition as well as a similar coarse fragment content 10 20 root and organic matter contents are significantly higher whereas calcium carbonate is significantly lower in the mound than in the intermound soils mounds may represent a relict land surface level lowered in the intermound area mainly by wash erosion mound development is related to discrete shrub clumps that shelter the underlying soil once established the shrub clump and the underlying mound remain as a stable and self maintained system

multiseismic cycle deformation rates from holocene normal fault scarps on crete greece morphotectonic features reveal recent seismic activity on normal faults on crete allowing slip rates palaeoearthquake magnitudes and earthquake recurrence intervals to be inferred the studied faults show major escarpments 100s m high 10s km long separating uplifted mesozoic rocks from quaternary deposits during the holocene slip rates outpaced erosion sedimentation rates and 5 15 m high fresh scarps formed at the base of the major escarpments based on our field observations and following empirical relationships between magnitude surface rupture length and maximum co seismic vertical displacement it is possible to infer some important seismotectonic parameter relative to the investigated faults taking into account the possible sources of error and the corresponding uncertainties our preferred long term slip rates range between 0 5 and 1 3 mm yr 1 the maximum expected magnitudes between 6 3 and 6 6 or 6 5 and 6 8 considering worst case scenarios while the mean recurrence intervals range between 260 and c 840 years these estimates are in good agreement with the shallow seismicity thus allowing to improve our knowledge on the seismic potential in crete horizontal extension rates could be also inferred from our geological data and compared with the few available gps data

seismicity and associated strain of central greece between 1890 and 1988 summary we examined the seismicity of central greece between 1890 and 1988 using macroseismic and instrumental data to ask two questions 1 does the seismicity of this period reveal all the major tectonic structures that are known to be active and 2 what are the likely strains associated with the seismicity over this period many known active structures have been effectively aseismic for the last hundred years and even the inclusion of all known large events earlier than 1890 reveals no activity associated with the ne coast of evia gulf of argos or graben ne of mt parnassos it is clear that even 100 years data are inadequate for either a reasonable assessment of seismic risk or for a confident estimation of maximum magnitude however we are aware of no earthquakes in central greece during the last 200 yr that were larger than ms 7 0 it is probable that the maximum magnitude is restricted by the maximum length of fault segments which appears to be around 15 20 km the earthquakes of ms 5 8 during 1890 1988 can account for a n s displacement of around 45 70 cm with maximum and minimum estimates a factor of two greater and smaller than this across part of a 1890 1900 triangulation network in central greece that was resurveyed in 1988 the contribution of smaller events may increase this displacement by about 50 per cent this cumulative seismic displacement is similar to that estimated from the geodetic work about 100 cm but a detailed comparison of the two sets of observations will be reported elsewhere a re evaluation of all the important earthquakes of 1890 1988 in central greece is presented in the appendix which summarizes information of use to both earth scientists and engineers

the tectonic geomorphology of bedrock scarps on active normal faults in the italian apennines mapped using combined ground penetrating radar and terrestrial laser scanning using combined datasets from ground penetrating radar gpr and terrestrial laser scanning tls we document the variety of tectono geomorphic features that contribute to the morphology of bedrock scarps associated with active extensional faulting in central italy measurement of faulted offsets across such scarps can provide important fault slip rate data relevant to seismic hazard analysis if ages can be established for offset features however interpretation of these offsets is challenging when geomorphic processes as well as fault slip contribute to exhumation of the bedrock during scarp development through the integration of surface tls and subsurface gpr datasets we show that the surface expression of three bedrock scarps results from the interaction between footwall incision hangingwall sedimentation channel incision and landsliding as well as fault slip and fault linkage we further illustrate how these processes can be differentiated to identify locations suitable for determining fault slip rates the identification of such features has important implications for our understanding of the relationship between bedrock faulting and geomorphic processes in turn contributing to improved assessment of fault slip rates in the central apennines the use of combined gpr and tls datasets here has shown that the tectono geomorphic features of the studied scarps vary greatly over short distances and we emphasise the need for detailed scarp analysis to elucidate the processes responsible for bedrock exhumation before estimating the rates of fault slip over the timescale of scarp formation