fault death a perspective from actively deforming regions abstract patterns of activity on large faults in regions of distributed continental deformation can change quite rapidly in less than 1 ma such changes include faults becoming permanently or temporarily inactive spatial migration of activity between different faults or faults sets within a deforming region and faults apparently going through episodes of intense activity separated by long quiescent periods greater knowledge of these changes combined with our increasingly detailed understanding of the geometry of large faults have implications for a variety of structural and tectonic issues such as 1 the nature of the interaction between neighbouring faults 2 the link between the discontinuous deformation on faults in the seismogenic upper crust and the more distributed deformation in the aseismic lithosphere beneath and 3 the relation between the instantaneous kinematics and the cumulative finite deformation examples from the active extensional province of central greece are used to illustrate the nature and possible significance of changing fault patterns

release fault a variety of cross fault in linked extensional fault systems in the sergipe alagoas basin ne brazil abstract two types of cross faults are herein recognized transfer faults and the newly termed release faults transfer faults form where cross faults connect distinct normal faults and horizontal displacements predominate over vertical ones in contrast release faults form where cross faults associated with individual normal faults die out within the hangingwall before connecting to other normal faults and have predominantly vertical displacements release faults are geometrically required to accommodate variable displacements along the strike of a normal fault thus they form to release the bending stresses in the hangingwall and do not cut normal fault planes nor detachment surfaces at depth release faults have maximum throws adjacent to normal faults and may be nearly perpendicular or obliquely oriented to the strike of the latter such geometry appears not to depend upon pre existing weaknesses but such variable orientation to normal faults is an inherent property of release faults release faults commonly appear as simple normal faults in seismic sections without implying extension along the strike of rift and basins three dimensional strain deformation occurs in the hangingwall only between the terminations of an individual normal fault but regionally release faulting is associated with plane strain deformation in linked extensional fault systems

linearized inversion of seismic reflection data this is the first of a series of papers giving the solution of the inverse problem in seismic exploration the acoustic approximation is used together with the assumption that the velocity field has the form the forward problem is then linearized thus neglecting multiple reflected waves and the inverse problem of estimating is set up its rigorous solution can be obtained using an iterative algorithm each step consisting of a classical kirchhoff migration hyperbola summation plus a classical forward modeling step circle summation

seismicity normal faulting and the geomorphological development of the gulf of corinth greece the corinth earthquakes of february and march 1981 three major destructive earthquakes of m s 6 7 6 4 6 4 occurred in the eastern part of the gulf of corinth in february and march 1981 associated normal faulting was observed on both the north and the south sides of the gulf examination of teleseismic local seismic surface faulting and geomorpbological data suggests that the first and second of these shocks activated major north dipping normal faults these faults control the topography and bathymetry and are related to the recent uplift and subsidence of the coastline it is probable that the first earthquake occurred on a faultwhich outcrops underwater and the second on a fault which is visible on land it appears that the third shock activated an antithetic normal fault dipping southwards on the north side of the gulf and that the overall structure of the gulf of corinth graben is asymmetric the northern antithetic fault clearly demonstrates the geomorphological changes associated with developing young normal faulting in addition we suggest that observations of recent coastline movement provide a powerful tool for identifying major active fault systems and predicting their historical role in the paleogeography of an area

finite difference calculation of traveltimes in three dimensions the traveltimes of first arriving seismic rays through most velocity structures can be computed rapidly on a three dimensional numerical grid by finite difference extrapolation head waves are properly treated and shadow zones are filled by the appropriate diffractions differences of less than 0 11 percent are found between the results of this technique and ray tracing for a complex but smooth model this scheme has proven useful for earthquake location and shows promise as an inexpensive well behaved substitute for ray tracing in forward modeling and kirchhoff inversion applications

controls on early rift geometry new perspectives from the bilila mtakataka fault malawi we use the 110 km long bilila mtakataka fault in the amagmatic southern east african rift malawi to investigate the controls on early rift geometry at the scale of a major border fault morphological variations along the 14 8 m high scarp define six 10 40 km long segments which are either foliation parallel or oblique to both foliation and the current regional extension direction as the scarp is neither consistently parallel to foliation nor well oriented for the current regional extension direction we suggest the segmented surface expression is related to the local reactivation of well oriented weak shallow fabrics above a broadly continuous structure at depth using a geometrical model the geometry of the best fitting subsurface structure is consistent with the local strain field from recent seismicity in conclusion within this early rift pre existing weaknesses only locally control border fault geometry at subsurface

structures in segment boundary zones of the lost river and lemhi faults east central idaho geologic mapping and structural analysis of the lost river and lemhi normal faults in east central idaho suggest that many rupture segment boundaries previously inferred from geomorphic data coincide with two classes of structural complexities 1 zones of distributed faults and steps or jogs in the range front faults and 2 intersections with preexisting eocene to oligocene cross faults at 10 15 km depth segment boundaries contain as many as 13 fault splays and are as much as 13 km long and 5 6 km wide in plan view in contrast simple fault traces characterize the range front faults in the interiors of segments thus segment boundaries of normal faults are broad zones of intersecting faults not discrete points the structural data further imply that segment boundaries contain large volumes of fractured and faulted rock and that zones of distributed normal faults have influenced rupture propagation and arrest along these two normal faults intersections of preexisting cross faults and range front faults may also have influenced the locations of rupture boundaries along the lost river and lemhi faults downdip projections of preexisting eocene to oligocene normal faults in the footwall of the lost river and lemhi faults may coincide with four or five segment boundary zones at about 15 km depth the depth at which large earthquakes nucleate in the basin and range province structural analyses also show that some cross faults which coincide with segment boundary zones at the surface are distant from these zones at depth conversely some potentially significant structures present at depth are far removed from the segment boundary zone at the surface thus a close spatial relationship between cross faults and segment boundary zones at the surface cannot prove or disprove a genetic relationship between these features because the near surface geometry of segment boundary zones may differ dramatically from the subsurface geometry of the zones where cross faults define segment boundaries the enhanced fracture toughness of preexisting fault planes and their damage zones may impede or arrest rupture on younger crosscutting faults

waveform tomography in 2 5d parameterization for crooked line acquisition geometry 1 a method for 2 5d viscoacoustic waveform tomography that can be applied to generate 2d models of velocity and attenuation from inversion of refraction waveforms on land seismic reflection data acquired along crooked roads is developed it is particularly useful for typical crustal reflection surveys first arrival travel time tomography is applied using a 3d method but with constraints on the intermediate 3d velocity model the result is the starting model for the next step a 2 5d frequency domain full waveform inversion stage parameterizes 3d geometry in the seismic source and receiver arrays with the assumption that the velocity and attenuation models are homogeneous in the out of plane direction this approach results in superior results compared to a strictly 2d approach when the acquisition line is crooked with a moderate increase in computational cost a case study using data acquired in the nechako basin in south central british columbia canada exemplifies and validates the procedure the velocity model derived from 2 5d waveform tomography is compared with that from a previous study in which 2d waveform tomography was applied to the same data set and with results from 3d travel time tomography the resolution and accuracy of the velocity model from 2 5d waveform tomography are demonstrated to be greater than those from travel time or 2d waveform tomography a model of viscoacoustic attenuation which was not possible in the 2d case is also generated these models are interpreted jointly to highlight features of geological interest such as a sedimentary basin basement rocks and faults from surface to about 3 km depth

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

active tectonics of the north and central aegean sea summary in this paper we examine the connection between the westward motion of turkey relative to europe and the extension in and around the aegean sea the principal new data available since the last attempt to synthesize the tectonics of this region by mckenzie 1978 are much improved focal mechanisms of earthquakes constrained by p and sh body wave modelling as well as by first motions these mechanisms show that the faulting in the western part of the aegean region is mostly extensional in nature on normal faults with a nw to wnw strike and with slip vectors directed nnw to nne there is evidence from palaeomagnetism that this western region rotates clockwise relative to stable europe in the central and eastern aegean and in nw turkey distributed right lateral strike slip is more prevalent on faults trending ne to ene and with slip vectors directed ne palaeomagnetic data in this eastern region is more ambiguous but consistent with very small or no rotations in the northern part and possibly anticlockwise rotations relative to europe in the south the strike slip faulting that enters the central aegean from the east appears to end abruptly in the sw against the nw trending normal faults of greece the kinematics of the deformation is controlled by three factors the westward motion of turkey relative to europe the continental collision between nw greece albania and the apulia adriatic platform in the west and the presence of the hellenic subduction zone to the south as the right lateral slip on the north anatolian fault enters the aegean region it splays out becoming distributed on several parallel faults the continental shortening in nw greece and albania does not allow the rotation of the western margin of the region to be rapid enough to accommodate this distributed e w right lateral shear and thus leads to e w shortening in the northern aegean which is compensated by n s extension as the southern aegean margin can move easily over the hellenic subduction zone the dynamics of the system once initiated is self sustaining being driven by the high topography in eastern turkey and by the roll back of the subducted slab beneath the southern aegean the geometry of the deformation resembles the behaviour of a system of broken slats attached to margins that rotate in spite of its extreme simplicity a simple model of such broken slats is able to reproduce quantitatively most of the features of the instantaneous velocity field in the aegean region including the slip vectors and nature of the faulting in the eastern and western parts the senses and approximate rates of rotation the overall extensional velocity across the aegean and the distribution of strain rates as seen in the seismicity and topography or bathymetry and using geodetic measurements as part of this study we re examined the relation between the surface faulting and the focal parameters determined seismologically for the three large 1981 gulf of corinth earthquakes and reassessed the evidence for associating particular earthquakes in the sequence with observed surface faulting an important result is that in one of the events there is a resolvable discrepancy between the slip vector measured at the surface and that determined from the seismic body waves

extensional fault cores in micritic carbonate case studies from the gulf of corinth greece abstract the major pisia and doumena faults of the corinth rift greece are both hosted by micritic carbonate rock their common fault elements are principal slip surfaces layers of fault rocks fault rock and host rock lenses corrugations and smaller shear and tension fractures along planar fault segments a corrugated slip surface with an associated thin fault rock layer is formed well developed down dip corrugations indicate movement along the same surface over many fault increments bends jogs in the faults are sites of complex structural relations hosting frequent lenses more porous fault rocks and dense networks of fractures major jogs in the slip surfaces have both strike and dip oriented undulating curvature that are associated with higher order fracture networks as well as frequent lenses fault core lens shapes of the doumena fault show relationship of length vs width of 3 2 similarly principal slip surfaces of the two faults show undulations with aspect ratios of amplitude vs wavelength 1 19 and 1 14 in strike direction despite a prominent difference in down dip geometry the intrinsic deformation in fault cores of micritic carbonate supports a model in which fluids entered the core by damage zone fractures that are linked to the principal slip surface flow along the fault core was controlled by the fracture system of lenses and thereby lens connectivity but may have been hampered by flow retarding fault rocks the flow potential is especially well developed in fault bends and breached relays due to frequent lenses and well developed fracture networks

new geophysical models for subsurface velocity structure in the nechako chilcotin plateau from 2 5 d waveform tomography1 seismic inversion is applied to generate physical property models p wave velocity and numerical attenuation for four profiles in the nechako chilcotin plateau region of south central british colu

the nucleation and rupture process of the 1981 gulf of corinth earthquakes from deconvolved broad band data summary source parameters of the largest three normal faulting earthquakes ms6 6 6 3 6 4 in the 1981 gulf of corinth greece sequence are determined using deconvolved broad band data recorded by arrays and single stations and a 2 d finite source model such a model enables the spatial extent rupture velocity and stress drop of the earthquakes to be determined and geological observations of surface slip can be included as a further constraint on the waveform modelling all three earthquakes were shallow lo km with low stress drops 30 bars and exhibited source complexity the correspondence between the complexity of the earthquake sources and that of the mapped fault breaks implies that the segmentation of surface faulting in greece is representative of faulting at depth tiny initial pulses which correlate across the arrays are seen in the seismograms from the gulf of corinth earthquakes at most stations these initial subevents 1 per cent of the total moment are interpreted as the breaking of small asperities which initiated the main rupture and are used to constrain the attenuation correction t 0 2 s

evidence from high resolution topography for multiple earthquakes on high slip to length fault scarps the bilila mtakataka fault malawi geomorphological features such as fault scarps and stream knickpoints are indicators of recent fault activity determining whether these features formed during a single earthquake or over multiple earthquakes cycles has important implications for the interpretation of the size and frequency of past events here we focus on the bilila mtakataka fault malawi where the 20 m high fault scarps exceed the height expected from a single earthquake rupture we use a high resolution digital elevation model 1 m to identify complexity in the fault scarp and knickpoints in river profiles of 39 selected scarp profiles 20 showed evidence of either multi scarps or composite scarps and of the seven selected river and stream profiles five showed evidence for multiple knickpoints a near uniform distribution of vertical offsets on the sub scarps suggests they were formed by separate earthquakes these independent methods agree that at least two earthquakes have occurred with an average vertical offset per event of 10 and 12 m this contrasts earlier studies which proposed that this scarp formed during a single event and demonstrates the importance of high resolution topographic data for understanding tectonic geomorphology we use a one dimensional diffusion model of scarp degradation to demonstrate how fault splays form multi scarps and estimate the diffusion age t of the bilila mtakataka fault scarp to be 48 m25 m2 corresponding to 6400 4000 years since formation we calculate that a continuous rupture would equate to a mw 7 8 0 3 earthquake greater than the largest seismic event previously recorded in east africa

lateral propagation of the surface trace of the south alkyonides normal fault segment central greece its impact on models of fault growth and displacement length relationships abstract the evolution of deformed marine terraces and drainage systems have been examined in order to investigate the growth and lateral propagation of an active normal fault geological mapping has revealed three distinct raised marine terraces in the immediate footwall of the western end of the active south alkyonides fault segment safs gulf of corinth central greece we correlate these terraces with sea level highstands at 125 240 and 330 ka using elevation estimates of the inner edges of the terraces we show that uplift rates decrease towards the perachora fault segment boundary at the western end of the safs analysis of terraces and drainage wind gaps in the footwall of the fault shows that the surface trace of the safs propagated westwards at a rate of 12 1 16 7 mm y over at least the last 330 ka whilst the surface trace length has increased analysis of the geometry and kinematics of fault slip suggests that fault length at depth has remained fixed implying progressive increase in the values for the displacement length ratio if this is correct growth is not self similar and fault length has been established early in the evolution of the system i e before 330 ka

quantitative imaging of complex structures from dense wide aperture seismic data by multiscale traveltime and waveform inversions a case study an integrated multiscale seismic imaging flow is applied to dense onshore wideaperture seismic data recorded in a complex geological setting thrust belt an initial p wave velocity macromodel is first developed by first arrival traveltime tomography this model is used as an initial guess for subsequent full waveform tomography which leads to greatly improved spatial resolution of the p wave velocity model however the application of full waveform tomography to the high frequency part of the source bandwidth is difficult due to the non linearity of this kind of method moreover it is computationally expensive at high frequencies since a finitedifference method is used to model the wave propagation hence full waveform tomography was complemented by asymptotic prestack depth migration to process the full source bandwidth and develop a sharp image of the short wavelengths the final traveltime tomography model and two smoothed versions of the final full waveform tomography model were used as a macromodel for the prestack depth migration in this study wide aperture multifold seismic data are used after specific preprocessing of the data 16 frequency components ranging from 5 4 hz to 20 hz were inverted in cascade by the full waveform tomography algorithm the full waveform tomography successfully imaged sw dipping structures previously identified as highresistivity bodies the relevance of the full waveform tomography models is demonstrated locally by comparison with a coincident vertical seismic profiling vsp log available on the profile the prestack depth migrated images inferred from the traveltime and the smoothed full waveform tomography macromodels are shown to be on the whole consistent with the final full waveform tomography model a more detailed analysis based on common image gather computations and local comparison with the vsp log revealed that the most accurate migrated sections are those obtained from the full waveform tomography macromodels a resolution analysis suggests that the asymptotic prestack depth migration successfully migrated the wideaperture components of the data allowing medium wavelengths in addition to the short wavelengths of the structure to be imaged

waveform tomography imaging of a megasplay fault system in the seismogenic nankai subduction zone abstract we apply frequency domain waveform tomography to form quantitative high resolution p wave velocity images of a megasplay fault system within the central nankai subduction zone offshore of southwest japan using controlled source ocean bottom seismometer obs data originally acquired in 2004 the waveform tomography method exploits recorded seismic waveforms beyond their first arrivals and thus achieves a much higher resolution of the order of a wavelength than that of conventional traveltime tomography methods frequency domain waveform tomography facilitates a multi scale approach to stabilize the inversion in which initial traveltime tomography results are sequentially improved on by first fitting low frequency components of the seismic records starting at 2 25 hz higher frequency components up to 8 5 hz are then introduced progressively our final waveform tomography image allows velocity anomalies as small as 700 m horizontally and 350 m vertically to be discerned and interpreted as confirmed by checkerboard modeling tests the improved explanatory power of the final images is verified by observing that synthetic waveforms calculated from the final results yield much better fit to the observed waveforms than those estimated from the original traveltime tomography image apparent lithological boundaries from waveform tomography agree well with corresponding reflections on seismic migration images providing further confidence in the validity of the results the megasplay fault is evident on the final waveform tomography image as a sharp velocity discontinuity delineating the upper surface of a velocity reduction of nearly 1 km s with respect to the regional 1d velocity trend the megasplay fault can be traced continuously throughout the entire image from a nearly horizontal section at the landward extent moving seaward through to a steeper angle penetrating the old accretionary prisms with several additional splays appearing to branch in the shallow subsurface the location of the low velocity zones imaged by our waveform tomography method coincides with two previously identified low velocity zones the image reveals a low velocity zone that is continuous from deeper to shallower portions of the subsurface suggesting that pore fluids may be transported from the inner wedge to the transition zone and to the surface through fluid conduits associated with the megasplay fault system

fault orientation variations along the strike of active normal fault systems in italy and greece implications for predicting the orientations of subseismic resolution faults in hydrocarbon reservoirs the orientations of subseismic scale faults vary systematically along the strike of basin bounding active normal faults in italy and greece a total of 16 272 outcrop measurements of the strike and dip of fault planes and their associated slip vectors indicate oblique slip near the lateral fault tips of the normal faults subseismic faults vary in orientation to accommodate this slip if viewed in map view from the footwall looking toward the hanging wall right lateral slip occurs at the left end of the faults with left lateral slip at the right end overall slip vectors converge toward the hanging wall with intersection lines for faults accommodating this slip parallel to the slip vector if the same faulting style applies elsewhere the empirical relationships presented herein can be used to calibrate results from mechanical fault models and provide a pragmatic guide to the orientations of normal fault bound compartments of rock in subsurface hydrocarbon reservoirs given that the offsets across such faults may be below seismic resolution and not amenable to direct measurement

advances and limitations of the environmental seismic intensity scale esi 2007 regarding near field and far field effects from recent earthquakes in greece implications for the seismic hazard assessment the new environmental seismic intensity scale esi 2007 introduced by inqua incorporates the advances and achievements of palaeoseismology and earthquake geology and evaluates earthquake size and epicentre solely from the earthquake environmental effects eee this scale is tested and compared with traditional existing scales for the 1981 alkyonides earthquake sequence in the corinth gulf ms 6 7 ms 6 4 ms 6 3 the 1993 pyrgos event ms 5 5 and the 2006 kythira event mw 6 7 these earthquakes were of different magni tudes focal mechanisms and focal depths and produced well documented environmental effects the esi 2007 intensity values and the isoseismal pattern for the 1993 pyrgos and the 2006 kythira events are similar to those resulting from the traditional scales demonstrating that for moderate intensity levels vii and viii the esi 2007 and the traditional scales comply well in contrast the 1981 alkyonides earthquake sequence shows that there is an inconsistency between the esi 2007 and the traditional scales both in the epicentral area where higher esi 2007 intensity values have been assigned and for the far field effects the esi 2007 scale offers higher objectivity in the process of assessing macroseismic intensities particularly in the epicentral area than traditional intensity scales that are influenced by human parameters the esi 2007 scale follows the same criteria environmental effects for all events and can compare not only events from different settings but also contemporary and future earthquakes with histori cal events a reappraisal of historical earthquakes so as to constrain the esi 2007 scale may prove beneficial for seismic hazard assessment by reducing the uncertainty implied in the attenuation laws which constitute one of the most important seismic hazard parameters

tectono sedimentary development of an extensional basin the neogene megara basin greece the miocene pliocene to pleistocene succession exposed in the megara basin comprises a grossly coarsening upwards sequence at least 1 km thick the oldest strata exposed in the nw record the establishment of alluvial fans and axial streams these drained into a lacustrine environment subject to minor wave and possibly tidal action the lower part of the central basin fill is comprised of marls siltstones sandstones and conglomerates they record the pulsed infill of the predominantly freshwater lake megara by progradation of a network of shallow multichannel streams which drained a western hinterland containing ultrabasic rocks cherts and limestones frequent examples of large scale soft sediment deformation structures and stratigraphic thickening into hangingwall rolloven indicate active fault control of sedimentation the lake river interface featured gilbert deltas which were subject to periodic transgression by climatically controlled lake expansions the upper part of the pliocene basin fill largely comprises fluviatile gravels but with two important marine transgressional horizons and renewed calcareous mar1 deposition including a basinwide tufa horizon towards the top the overlying pleistocene alluvial clastics were deposited by a nw flowing system and thicken markedly into a major basin bounding fault deposition of these fluvial deposits was interrupted towards the top of the sequence by the rapid deposition of monomict limestone breccias of debris flow origins which are believed to mark a catastrophic event at some time in the late pleistocene c 1 ma the basin bounding faults became inactive and the entire basin fill was inverted in response to uplift in the footwall of the active major fault strand that bounds the se margin of the alkyonides gulf

high resolution seismic attenuation imaging from wide aperture onshore data by visco acoustic frequency domain full waveform inversion summary here we assess the potential of the visco acoustic frequency domain full waveform inversion fwi to reconstruct p wave velocity vp and p wave attenuation factor q from surface onshore seismic data first we perform a sensitivity analysis of the fwi based upon a grid search analysis of the misfit function and several synthetic fwi examples using velocity and q models of increasing complexity subsequently we applied both the acoustic and viscoacousticfwitorealsurfacewide apertureonshoreseismicdatafromthepolishbasin wherea strongattenuationoftheseismicdataisobserved thesensitivityanalysisofthevisco acoustic fwi suggests that the fwi can jointly reconstruct the velocity and the attenuation factor if the signatureoftheattenuationissufficientlystronginthedata asyntheticexamplecorresponding to a homogeneous background model with an inclusion shows a reliable reconstruction of vp and q in the inclusion when q is as small as 90 and 50 in the background model and in the inclusion respectively a first application of acoustic fwi to real data shows that a heuristic normalization of the data with offset allows us to compensate for the effect of the attenuation in the data and reconstruct a reliable velocity model alternatively we show that visco acoustic fwi allows us to reconstruct jointly both a reliable velocity model and a q model from the true amplitude data we propose a pragmatical approach based upon seismic modelling and source wavelet estimation to infer the best starting homogeneous q model for visco acoustic fwi we find the source wavelet estimation quite sensitive to the quality of the velocity and attenuation models used for the estimation for example source to source wavelets are significantly more consistent when computed in the final fwi model than in the initial one a good kinematic and amplitude match between the early arriving phases of the real and time domain synthetic seismograms computed in the final fwi model provides an additional evidence of the reliability of the final fwi model we find the recovered velocity and attenuation models consistent with the expected lithology and stratigraphy in the study area we link high attenuation zones with the increased clay content and the presence of the mineralized fluids

scaling properties within the gulf of corinth greece comparison between offshore and onshore active faults abstract the gulf of corinth greece is a 110 km long by 30 km wide active graben displaying strong seismicity hosted both on north and south dipping normal faults this complex fault pattern consists of two fault populations offshore and onshore the offshore fault population is investigated by densely arranged seismic reflection profiles during the last 20 years whereas the onshore fault population displays spectacular and well exposed faults delineated by high accuracy mapping we analyzed fault length and throw in order to study the scaling properties of 136 well determined offshore and onshore faults and the comparison between the two datasets we examined the statistical properties on both fault populations in order to describe the role of segmentation in the growth of faults and the different stages of the evolution of the fault networks our results on power law relationships associated with the scaling properties of the fault zones in the gulf of corinth suggest that both fault populations are bi fractal providing the initiation of a sature state in deformation in addition the vertical throw of faults shows that both fault populations have similar properties but different distributions below and above 5 km respectively displacement length ratios show that faults larger than 9 km appear to accumulate throw without any dramatic change to their length these observations combined with other geophysical studies within the gulf suggest that the characteristic fault lengths of 5 km and 9 km can be correlated to the crustal mechanical structure and the seismicity of the gulf

elastic full waveform inversion of multicomponent ocean bottom cable seismic data application to alba field u k north sea elastic full waveform inversion of multichannel seismic data represents a data driven form of analysis leading to direct quantification of the subsurface elastic parameters in the depth domain previous studies have focused on marine streamer data using acoustic or elastic inversion schemes for the inversion of p wave data in this paper p and s wave velocities are inverted for using wide angle multicomponent ocean bottom cable obc seismic data inversion is undertaken using a two dimensional elastic algorithm operating in the time domain which allows accurate modeling and inversion of the full elastic wavefield including p and mode converted ps waves and their respective amplitude variation with offset avo responses results are presented from the application of this technique to an obc seismic data set from the alba field north sea after building an initial velocity model and extracting a seismic wavelet the data are inverted instages in the first stage the intermediate wavelength p wave v

application of waveform tomography to a crooked line 2d land seismic data set abstractonshore hydrocarbon exploration in the back arc region of japan suffers from seismic imaging challenges seismic data are typically acquired in a difficult environment along a crooked line over a rough surface topography underlain by severe near surface weathering layers the area is geologically complex and prestack depth processing is desirable however the data quality is suboptimal at near offsets and it hinders the migration velocity analysis required for depth processing thus a geologic interpretation needs to rely on time processing results nevertheless some data sets are rich in low frequency components and contain clear refracted and wide angle reflected waves both of which are favorable conditions for the application of waveform tomography we have used one such data set and we determined the applicability of waveform tomography to estimate the p wave velocity distribution to mitigate difficulties in the data we carefully optimized waveform tomography strategies and diligentl

application of waveform tomography to marine seismic reflection data from the queen charlotte basin of western canada to obtain a higher resolution quantitative p wave velocity model 2d waveform tomography was applied to seismic reflection data from the queen charlotte sedimentary basin off the west coast of canada the forward modeling and inversion were implemented in the frequency domain using the visco acoustic wave equation field data preconditioning consisted of f k filtering 2d amplitude scaling shot to shot amplitude balancing and time windowing the field data were inverted between 7 and 13 66 hz with attenuation introduced for frequencies 10 5 hz to improve the final velocity model two different approaches to sampling the frequencies were evaluated the limited maximum offset of the marine data 3770 m and the relatively high starting frequency 7 hz were the main challenges encountered during the inversion an inversion strategy that successively recovered shallow to deep structures was designed to mitigate these issues the inclusion of later arrivals in the waveform tomography resulted in a veloci

sedimentation and tectonic geomorphology adjacent to major active and inactive normal faults southern greece the active psatha skinos normal fault is uplifting a contrasting variety of lithologies in its footwall including mesozoic limestones ophiolitic peridotites and poorly consolidated plio pleistocene sediments of the inactive megara basin in the latter basin linear marginal uplands border the sedimentary fill and are interpreted as degraded and segmented scarp lines which exhibit features such as facetted spurs drainage domains are defined as groups of drainage basins sharing a common tectono geological substrate contrasting domains in the footwall of the active fault have given rise to spectacular differences in drainage basin growth and form in the uplifting footwall raised coastal terrace levels are present at about 10 and 40 m the latter have yielded corals dated at between 90 126 ka and have enabled us to calculate uplift and erosional rates extrapolation of these rates indicate that some 350 m of footwall relief has been produced over approximately 1 ma most of the sediment eroded from the uplifting footwall is presumed to have been re sedimented into the alkyonides gulf basin plain during this time the prominent footwall unconformity so produced forms a fine modern analogue to features seen in ancient syn rift tilt blocks such as the viking graben footwall uplift has also backtilted the former depositional surface of the megara basin and caused reversal of flow in its axial drainage domain a variety of depositional environments are documented in the subsiding hangingwall to the coastal fault including syn quake talus cones alluvial fans intra fan marshes and swamps truncated fans transgressive barriers and spits

localization of quaternary slip rates in an active rift in 105 years an example from central greece constrained by 234u 230th coral dates from uplifted paleoshorelines mapping dating and modeling of paleoshorelines uplifted in the footwall of the 1981 gulf of corinth earthquake fault greece ms 6 9 6 7 are used to assess its slip rate history relative to other normal faults in the area and study strain localization the 234u 230th coral ages from cladocora caespitosa date uplifted shoreface sediments and paleoshorelines from glacioeustatic sea level highstands at 76 possibly 100 125 175 200 216 240 and 340 ka uplifted quaternary and holocene paleoshorelines decrease in elevation toward the western tip of the fault exhibiting larger tilt angles with age showing that uplift is due to progressive fault slip since 125 ka uplift rates varied from 0 25 to 0 52 mm yr over a distance of 5 km away from the fault tip tilting was also occurring prior to 125 ka but uplift rates were lower because the 125 ka paleoshoreline is at 77 of the elevation of the 240 ka paleoshoreline despite being nearly half its age comparison of paleoshoreline elevations and sedimentology with the quaternary sea level curve shows that slip rates increased by a factor of 3 2 0 2 at 175 75 ka synchronous with cessation of activity on a neighboring normal fault at 382 112 ka we suggest that the rapid localization of up to 10 15 mm yr of extension into the narrow gulf 30 km wide resulted from synchronous fault activity on neighboring faults followed by localization rather than sequential faulting with consequences for the mechanism controlling localization of extension

underlying structural control of small scale faults and fractures in west candor chasma mars 1 orientations of small scale faults and fractures within the interior layered deposits of west candor chasma were measured to investigate what information about the geologic history of valles marineris they can contribute deformational features were separated into six categories based on morphology and their orientations were analyzed the elevations at which the deformational features formed are recorded as a proxy for stratigraphic level deformational features occur over a continuous range of elevations and display regionally consistent preferred orientations indicating their formation was controlled by a regional stress regime the two most abundant preferred orientations of 35 and 110 are approximately parallel to the chasma walls and the inferred underlying normal faults the alignment of three populations of small faults at 140 consistent with the morphology of release faults indicates a large scale fault underlying the southeastern border of ceti mensa the preferred orientations imply these small scale deformational features formed from a continuation of the same imposed stresses responsible for the formation of valles marineris indicating these stresses existed past the formation of the interior layered deposits the origins of a fourth preferred orientation of 70 is less clear but suggests the study area has undergone at least two periods of deformation

fault specific gis based seismic hazard maps for the attica region greece abstract traditional seismic hazard assessment methods are based on the historical seismic records for the calculation of an annual probability of exceedance for a particular ground motion level a new fault specific seismic hazard assessment method is presented in order to address problems related to the incompleteness and the inhomogeneity of the historical records and to obtain higher spatial resolution of hazard this method is applied to the region of attica which is the most densely populated area in greece as nearly half of the country s population lives in athens and its surrounding suburbs in the greater athens area the methodology is based on a database of 24 active faults that could cause damage to attica in case of seismic rupture this database provides information about the faults slip rates lengths and expected magnitudes the final output of the method is four fault specific seismic hazard maps showing the recurrence of expected intensities for each locality these maps offer a high spatial resolution as they consider the surface geology despite the fact that almost half of the attica region lies on the lowest seismic risk zone according to the official seismic hazard zonation of greece different localities have repeatedly experienced strong ground motions during the last 15 kyrs moreover the maximum recurrence for each intensity occurs in different localities across attica highest recurrence for intensity vii 151 156 times over 15 kyrs or up to a 96 year return period is observed in the central part of the athens basin the maximum intensity viii recurrence 115 times over 15 kyrs or up to a 130 year return period is observed in the western part of attica while the maximum intensity ix 73 77 15 kyrs or a 195 year return period and x 25 29 15 kyrs or a 517 year return period recurrences are observed near the south alkyonides fault system which dominates the strong ground motions hazard in the western part of the attica mainland

coseismic throw variation across along strike bends on active normal faults implications for displacement versus length scaling of earthquake ruptures fault bends and associated changes in fault dip play a key role in explaining the scatter in maximum offset versus surface rupture length fault scaling relationships detailed field measurements of the fault geometry and magnitude of slip in the 2016 2017 central italy earthquake sequence alongside three examples from large historical normal faulting earthquakes in different tectonic settings provide multiple examples in which coseismic throw increases across bends in fault strike where dip also increases beyond what is necessary to accommodate a uniform slip vector coseismic surface ruptures produced by two mainshocks of the 2016 2017 central italy earthquake sequence 24 august 2016 mw 6 0 and 30 october 2016 mw 6 5 cross a 0 83 km amplitude along strike bend and the coseismic throws for both earthquakes increase by a factor of 2 3 where the strike of the fault changes by 28o and the dip increases by 20 25o we present similar examples from historical normal faulting earthquakes 1887 sonora earthquake mw 7 5 1981 corinth earthquakes mw 6 7 6 4 and 1983 borah peak earthquake mw 7 3 we demonstrate that it is possible to estimate the expected change in throw across a bend by applying equations that relate strike dip and slip vector to horizontal strain conservation along a nonplanar fault for a single earthquake rupture the calculated slip enhancement in bends can explain much of the scatter in maximum displacement dmax versus surface rupture length scaling relationships if fault bends are unrecognized they can introduce variation in dmax that may lead to erroneous inferences of stress drop variability for earthquakes and exaggerate maximum earthquake magnitudes derived from vertical offsets in paleoseismic data sets

shape and structure of the salzach valley austria from seismic traveltime tomography and full waveform inversion summary a 3 km long wide angle seismic survey across the salzach valley in the eastern alps austria provides a detailed characterization of its structure reflection and refraction traveltime tomography with adaptive gridding was applied to obtain a minimum structure model more detailed images of the valley fill were derived by acoustic full waveform inversion a multiscale frequency domain method was applied to data in the 4 26 hz range to improve the resolution from several hundred metres to less than fifty metres the starting frequency is unusually low for the size of the survey and it provides additional control of the long wavelengths of the background model which mitigates the non linearities of the inversion the final image is controlled by independent constraints from resistivity data and shallow wells it shows a confined upper aquifer that overlies a 150 m thick unsaturated zone no strong evidence was found for consolidated sediments at the bottom of the basin this and the large maximum depth to bedrock of 480 m suggests that the valley fill was repeatedly removed during strong glacial periods exposing the bedrock to deep erosion

quaternary evolution of the corinth rift and its implications for the late cenozoic evolution of the aegean summary we present geological and morphological observations at different scales to constrain rates of faulting and the distribution of deformation in the seismically active aegean region we focus first on the 130 km long corinth rift an asymmetric graben where a flight of terraces of marine origin are uplifted we show that the edges of the terraces lie in the footwall of the normal fault bounding the corinth rift and correspond to sea level highstands of laic pleistocene age using a detailed analysis of aerial and spot imagery supported by field observations we have mapped 10 terrace platforms and strandlines ranging in elevation from 10 to 400 m over distances of 2 to 20 km from the fault the elevation of the terraces inner edges was estimated at 172 sites with an error of 5m this data set contains a precise description of the uplift and flexure of 10 different palaeohorizontal lines with respect to the present sea level to date the deformation we correlate the corinth terraces with late pleistocene oxygen isotope stages of high sea level stands and with global sea level fluctuations using a thick elastic plate model consistent with our current understanding of the earthquake cycle and a boundary element technique we reproduce the geometry of the shorelines to constrain both mechanical parameters and the slip on the fault we show that the seismogenic layer behaves over the long term as if its elastic modulus were reduced by a factor of about 1000 all the terraces are fitted for fault slip increasing in proportion to terrace age and the component of regional uplift is found to be less than 0 3 mm yr 1 the best fits give a slip rate of 11 3 mm yr 1 on the main rift bounding fault over the last 350 kyr other geological and morphologic information allows us to estimate the total age of the main fault 1 ma and to examine the mechanical evolution of the corinth rift the minimum observed sediment thickness in the gulf places an extreme check on the results of the modelling and a lower bound on slip rate of 6 7 mm yr 1 40 per cent less than estimated with modelling even this slip rate is nearly 10 times higher than for comparable features in most of the aegean and elsewhere in the world at a larger scale the spacing and asymmetry of the rift systems in the aegean suggest strain localization in the upper mantle with slow extension starting 15 myr ago or earlier the more recent 1 myr rapid phase of rifting in corinth partly reactivated this earlier phase of extension the younger faulting in corinth appears to result from its present location in the inhomogeneous stress field process zone of the south westward propagating tip of the southern branch of the north anatolian fault we extend these relations to propose a mechanical model for the late cenozoic evolution of the aegean as the arabia europe collision progressed in eastern turkey it caused anatolia to move to the west and the north anatolian fault to propagate into the aegean where the early slow extension started to be modified about 5 ma ago the process of propagation dramatically increased the activity of some but not all of the earlier rifts the model we present is compatible with tectonic observations as well as with the seismicity the palaeomagnetic rotations and the displacement field now observed with gps and slr

sinkhole distribution in a rapidly developing urban environment hillsborough county tampa bay area florida sinkhole formation in florida is a common event the florida karst plain is significantly altered by human development and sinkholes cause considerable property damage throughout much of the state we present in this paper a morphometric analysis of karst depressions in the tampa bay area and the relation with the known distribution of sinkholes we selected the tampa bay area because it is particularly susceptible to the evolution of karst depressions in relation with development of the built up environment karst depressions were mapped from the 1 24 000 usgs topographic maps and a morphometric analysis was performed by using parameters such as shape circularity index perimeter area length width and orientation maps showing the distribution of depression density and the sectors with greatest areas of karst depression were produced using a gis these results were compared with data compiled from the database of sinkhole occurrences in florida maintained by the florida geological survey our analysis demonstrates that the distribution of new sinkhole occurrences differs from the distribution of existing sinkholes indicating that there are processes acting today that are influencing karst landscape formation that are different from those acting in the past

geometry and kinematics of active normal faults south oquirrh mountains utah implication for fault growth the nnw striking south oquirrh mountains normal fault zone consists of four individual faults the individual faults are arranged in a right stepping pattern in the north and a left stepping pattern in the south forming a convex shaped fault zone in map view with the apex towards the hanging wall late quaternary fault activity is characterized by 2 0 4 5 m high discontinuous fault scarps developed in both late quaternary alluvium and bedrock the fault scarps in bedrock contain evidence of two large rupture events the last large earthquake occurred prior to the highstand of the bonneville lake cycle 15 ka based on cross cutting relationship between the bonneville shoreline and the fault scarp and on comparisons of fault scarp morphology cumulative displacement patterns inferred from range crest elevations bouguer gravity data in the adjacent basin and rotation of the subsidiary faults adjacent to the west mercur fault are similar to the pattern of displacements measured across late quaternary fault scarps that is the maximum displacement is near the apex of the convex shaped fault zone where the west mercur fault is located and then tapers off towards both ends of the fault zone fault traces that range from a few meters to tens of kilometers long are characterized by two dominant orientations strike n11 w and n43 w the two orientations are separated from each other by a statistically constant angle of 33 3 slip directions concentrate on a trend of s70 w for both groups of faults perpendicular to the average strike of the fault zone these data indicate that the geometry of the fault surfaces is non cylindrical and may be composed of self similar structural ridges and troughs of variable wavelength and amplitude that are elongated parallel to slip direction the relationships between fault geometry displacement and geomorphology in the south oquirrh mountains fault zone suggests a growth model of normal faults in which apex points on the convex shaped fault sections mark the nucleation points of primary faults secondary faults developed at the ends of the primary fault step into the footwall block as the fault zone grows laterally intersecting regions between two laterally growing fault zones are concave shaped in map view

three dimensional seismic refraction tomography a comparison of two methods applied to data from the faeroe basin this paper presents a comparison of two tomographic methods for determining three dimensional 3 d velocity structure from first arrival travel time data the first method is backprojection in which travel time residuals are distributed along their ray paths independently of all other rays the second method is regularized inversion in which a combination of data misfit and model roughness is minimized to provide the smoothest model appropriate for the data errors both methods are nonlinear in that a starting model is required and new ray paths are calculated at each iteration travel times are calculated using an efficient implementation of an existing method for solving the eikonal equation by finite differencing both inverse methods are applied to 3 d ocean bottom seismometer obs data collected in 1993 over the faeroe basin consisting of 53 479 travel times recorded at 29 obss this is one of the most densely spaced large scale 3 d seismic refraction experiments to date different starting models and values for the free parameters of each tomographic method are tested a new form of backprojection that converges more rapidly than similar methods compares favorably with regularized inversion but the latter method provides a simpler model for little additional computational expense when applied to the faeroe basin data bounds on two model features are assessed using regularized inversion with combined smoothness and flatness constraints an inversion of synthetic data corresponding to 100 data recovery from the real experiment shows a marked improvement in lateral resolution at deeper depths and demonstrates the potential of currently feasible 3 d refraction experiments to provide well resolved long wavelength velocity models the similarity of the final models derived from the two tomographic methods suggests that the results from the new form of backprojection can be relied on when limited computational resources rule out regularized inversion

scales of structural heterogeneity within neotectonic normal fault zones in the aegean region abstract structural heterogeneities within neotectonic normal fault zones in the aegean region are important controls on the geomorphic expression of their uplifted footwall blocks contrasting fault rocks and slip plane phenomena corrugations comb fractures slip parallel fractures and pluck holes are responsible for mesoscopic inhomogeneities within fault scarps along strike disruptions in the continuity of fault scarps step over zones step up zones step down zones footwall cross faults and hangingwall cross faults are products of perturbations in slip plane geometry or intersections with transverse faults large scale variations in range front morphology reflect contrasting patterns of deformation within fault zones some major fault zones and many minor fault zones are characterized by a migration of the active slip plane towards the hangingwall resulting in a distributed network of high angle faults and a range front which is stepped in profile the presence of a localized mass of uneroded bedrock hangingwall salients protruding from the hangingwall of some major fault zones results in intense deformation along a principal slip plane and a range front which is ramp like in profile as a consequence of structural heterogeneities within neotectonic normal fault zones fault scarps and range fronts in the aegean region are subject to a temporally and spatially variable pattern of degradation

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

the geometry kinematics and rates of deformation within an en echelon normal fault segment boundary central italy abstract the geometry kinematics and rates of deformation have been investigated within an en echelon fault segment boundary between two left stepping major normal faults in the central apennines italy examination of faulted post glacial sediments and geomorphic features attributed to glacial retreat 18 ka reveals that the two major faults dominate the recent slip with rates that are 5 10 times greater than the other faults at the centres of the major faults slip is parallel to the regional extension direction ne sw defined by focal mechanisms and borehole breakouts slip vector azimuths defined by striations on faults in the stepover zone indicate ne sw extension on nw se faults sub parallel to the regional extension direction together with significant and contemporaneous nw se extension along the strike of the apennines on ese wnw and ene wsw faults thus distributed three dimensional strain occurs in the stepover between the two major bounding faults extension rates summed across the stepover are 0 68 mm y parallel to the regional extension compared to 2 mm y at the centre of one of the major faults extension rates along strike of the fault zone are 0 14 mm y within the stepover and zero at the centres of the two major bounding faults the above information is used to discuss how extension is partitioned between different structures during the growth and linkage of normal faults

the tectono sedimentary evolution of the lechaion gulf the south eastern branch of the corinth graben greece abstract the gulf of corinth is the second most active continental rift in the world and thus a much studied natural laboratory for analyzing details of rift history a new detailed offshore seismic survey combined with previously acquired data in its least studied part the lechaion gulf shed light on the tectono sedimentary evolution of the eastern end of the corinth rift this study shows that i the lechaion gulf is the submerged northern part of the onshore corinth nemea basin ii they are both bounded to the south by the north dipping klenia and kenchreai faults which are considered at present inactive iii both the corinth nemea basin and the lechaion gulf were formed at around between 3 6 and 4 ma bp middle to late pliocene at the same time with the megara basin and iv the lechaion gulf was submerged and took its present shape at around between 0 7 and 1 7 ma bp at the same time with the gulf of corinth and the alkyonides gulf furthermore sequence stratigraphy interpretation of seismic profiles from the lechaion gulf revealed i a total post alpine sediment thickness of almost 3 km below the lechaion gulf ii at least 400 m of sediments accumulated during the last 245 ka corresponding to a mean sedimentation rate of 1 m ka for the last 245 ka and 2 3 m ka for the holocene and iii differential vertical movement in the order of 4 5 km between the bedrock under the lechaion gulf and the adjacent mountains yields an accumulative average slip rate of 0 9 m ka or less over the last 4 ma therefore for estimating more accurately the slip rates the uplift rates the extensional rates and the earthquake recurrence interval over the eastern end of the corinth rift the presently mentioned tectono sedimentary evolution of the lechaion gulf must be taken into consideration

geodetic estimate of seismic hazard in the gulf of korinthos the recent 15 june 1995 m0 6 0 1018 n m aigion earthquake in the western gulf of korinthos has focussed attention on the seismic hazard of the region although there have been few large earthquakes in the region during this century the historical record suggests that there may have been many large earthquakes there in the interval 1750 1900 we present geodetic data that give estimates of the rate of extension of the gulf of korinthos during this century and which suggest that less than half of the elastic strain in the central and western gulf of korinthos has been released by earthquakes during this century in contrast the seismic and geodetic strains in the eastern gulf of korinthos are in agreement with each other if the discrepancy between seismic and geodetic strains in the western gulf of korinthos that has accumulated during this century is removed in earthquakes the moment release will be equivalent to several ms 6 5 earthquakes

normal faulting and crustal deformation alkyonides gulf and perachora peninsula eastern gulf of corinth rift greece geophysical structural geochronological and geomorphological data indicate that the psatha east alkyonides skinos and pisia faults are holocene active structures whereas the status of the west alkyonides strava perachora and loutraki faults is less certain we see no evidence for significant lateral surface fault growth new data for late pleistocene footwall uplift of the psatha fault are comparable with previously estimated holocene rates pre holocene stratigraphic sequences in the alkyonides gulf allow calculation of vertical displacement on the skinos fault of 1 42 1 60 km over a period of 0 6 ma previous palaeoseismological studies indicate comparable displacement rates extrapolated to 0 61 2 20 ma whereas extrapolation of previous geodetic data indicate a range of 0 17 0 46 ma the latter is too short given the evidence of the stratigraphic record signifying either that these data may not be representative of longer term rates or that significant deformation has taken place elsewhere for example on offshore antithetic faults a case is established for uniform late quaternary post mis 7 uplift of the perachora peninsula at rates of c 0 2 0 3 mm a 1 the lack of regional tilting over perachora corinth isthmia is in marked contrast to the situation in the alkyonides megara basins to the east

geodetic determination of tectonic deformation in central greece from 1900 to 1988 the global positioning system has been used to measure the relative displacements of fifteen monuments in a hundred year old triangulation network spanning part of the aegean extensional basin these displacements reflect the tectonic deformation of the region over the past century showing more than one metre of north south extension across the network the crust in this region appears to contain a few slowly deforming blocks separated by more rapidly deforming zones

kinematic indicators on active normal faults in western turkey quaternary normal fault zones in western turkey comprise multiple slip planes and zone parallel layers of fault breccia they also contain several little known kinematic indicators that are probably typical of many formed at shallow levels in extending terrains the recent exhumation by contractors of about 2000 m2 of slip planes in a sse dipping fault zone separating quaternary colluvium from bedrock carbonates at yavansu 7 km se of kusadasi permits an unusually complete inventory of the indicators to be compiled the most spectacular indicators are metre scale 69 w pitching corrugations in slip planes and recemented breccia sheets underlying them corrugations characterized by sinusoidal profiles normal to their long axes and less commonly culminations and depression along their axes possibly developed as a result of upwards propagating slip planes seeking undemanding pathways through heterogeneous fault precursor breccias that formed in advance of tip lines parallel to corrugation long axes are those of gutters flat floored sleep sided channels a few centimetres wide probably related to the abrasion of subslip plane breccia sheets centimetre scale tool tracks scored in the uppermost subslip plane breccia sheet by resistant colluvial clasts are irregular at their proximal ends but distally they swing into alignment with corrugation axes frictional wear striae centimetres long but only a few millimetres wide and pitching 78 w are superimposed on the other slip parallel lineations comb fractures nearly perpendicular to slip planes define an intersection lineation which is normal to corrugation axes fault plane solutions of earthquakes on sse dipping active faults in the west anatolian extensional province indicate that mainly normal combined with minor dextral slip is the dominant mode a conclusion in accord with the sense of slip inferred from the indicators exposed on the yavansu slip planes

comparison of surface slip and focal mechanism slip data along normal faults an example from the eastern gulf of corinth greece abstract focal mechanism and surface slip data are used to investigate whether kinematics are similar at depth and at the surface along an active normal fault in the gulf of corinth greece we present a new database of slip data from the lateral termination of the south alkyonides fault segment safs and the en echelon stepover between it and an adjacent fault and use published data on surface slip and focal mechanism data pertaining to slip at depth during the 1981 alkyonides earthquake sequence the focal mechanisms exhibit similar fault plane orientations and kinematics to those measured at the surface within the stepover both data sets show that contemporaneous c n s and c e w extension is being accommodated by c e w and c n s oriented normal faults and the overall deformation is distributed oblate vertical flattening the deviation of the surface slip direction from 350 increases with distance from the centre of the safs the deviation of the focal mechanism t axes from 350 fit well with the surface data implying that the coseismic slip on the safs at depths of 7 10 km exhibits a similar kinematic pattern as that observed at the surface our results imply that it is critical to know the along strike position of data on a fault if either focal mechanisms or surface slip are to be used to infer regional strain and stress trajectories

distributed normal faulting in the tip zone of the south alkyonides fault system gulf of corinth constrained using 36cl exposure dating of late quaternary wave cut platforms abstract the geometry rates and kinematics of active faulting in the region close to the tip of a major crustal scale normal fault in the gulf of corinth greece are investigated using detailed fault mapping and new absolute dating fault offsets have been dated using a combination of 234u 230th coral dates and in situ 36cl cosmogenic exposure ages for sediments and wave cut platforms deformed by the faults our results show that deformation in the tip zone is distributed across as many as eight faults arranged within 700 m across strike each of which deforms deposits and landforms associated with the 125 ka marine terrace of marine isotope stage 5e summed throw rates across strike achieve values as high as 0 3 1 6 mm yr values that are comparable to those at the centre of the crustal scale fault 2 3 mm yr from holocene palaeoseismology and 3 4 mm yr from gps geodesy the relatively high deformation rate and distributed deformation in the tip zone are discussed in terms of stress enhancement from rupture of neighbouring crustal scale faults and in terms of how this should be considered during fault based seismic hazard assessment

two dimensional velocity models from wide angle seismic data by wavefield inversion summary modern wide angle surveys are often multi fold and multi channel with densely sampled source and receiver spacings such closely spaced data are potentially amenable to multi channel techniques involving wavefield propagation methods such as those commonly used in reflection data processing however the wide angle configuration requires techniques capable of handling very general wave types including those not commonly used in reflection seismology this is a situation analogous to that faced in cross borehole seismics where similar wave types are also recorded in a real cross borehole example we compare pre stack migration traveltime tomography and wavefield inversion we find that wavefield inversion produces images that are quantitative in velocity as are the tomograms but are of significantly higher resolution the wavefield inversion results have a resolution comparable to that of the qualitative pre stack migration images we seek to extend this novel development to the larger scale problem of crustal imaging an essential element of the approach we adopt is its formulation entirely within the temporal frequency domain this has three principal advantages 1 we can choose to decimate the data by selecting only a limited number of frequency components to invert thus making inversion of data from large numbers of source positions feasible 2 we can mitigate the notorious non linearity of the seismic inverse problem by progressing from low frequency components in the data to high frequency components and 3 we can include in the model any arbitrary frequency dependence of inelastic attenuation factors q and indeed solve for the spatial distribution of q an initial synthetic test with an anomaly located within the middle crust yields a velocity image with the correct structural features of the anomaly and the correct magnitude of velocity anomaly this is related to the fact that the reconstruction is obtained from forward scattered waves under these conditions the method thus behaves much like tomography a second test with a deeper more extensive anomaly yields an image with the correct velocity polarity and the correct location but with a deficiency in low and high wavenumbers in this case this is because the reconstruction is obtained from backscattered waves under these conditions the method behaves not like tomography but like migration a more extensive test based on a large wide angle survey in south eastern california and western arizona demonstrates a real potential for high resolution imaging of crustal structures although our results are limited by the acoustic approximation and by the relatively low frequencies that we can model today the images are sufficiently encouraging to warrant future research the problem of local minima in the objective function is the most significant practical problem with our method but we propose that appropriate layer stripping methods can handle this problem

statistical mechanics and scaling of fault populations with increasing strain in the corinth rift scaling properties of fracture fault systems are studied in order to characterize the mechanical properties of rocks and to provide insight into the mechanisms that govern fault growth a comprehensive image of the fault network in the corinth rift greece obtained through numerous field studies and marine geophysical surveys allows for the first time such a study over the entire area of the rift we compile a detailed fault map of the area and analyze the scaling properties of fault trace lengths by using a statistical mechanics model derived in the framework of generalized statistical mechanics and associated maximum entropy principle by using this framework a range of asymptotic power law to exponential like distributions are derived that can well describe the observed scaling patterns of fault trace lengths in the rift systematic variations and in particular a transition from asymptotic power law to exponential like scaling are observed to be a function of increasing strain in distinct strain regimes in the rift providing quantitative evidence for such crustal processes in a single tectonic setting these results indicate the organization of the fault system as a function of brittle strain in the earth s crust and suggest there are different mechanisms for fault growth in the distinct parts of the rift in addition other factors such as fault interactions and the thickness of the brittle layer affect how the fault system evolves in time the results suggest that regional strain fault interactions and the boundary condition of the brittle layer may control fault growth and the fault network evolution in the corinth rift

seismic reflection constraints on upper crustal structures in the volcanic covered central nechako basin british columbia1this article is one of a series of papers published in this special issue on the theme of new insights in cordilleran intermontane geoscience reducing exploration risk in the mountain pine beetle affected area british columbia in 2008 a vibroseis seismic reflection survey was acquired by geoscience bc across the eastern part of the volcanic covered nechako basin in central british columbia where cretaceous sedimentary rocks have been exhumed along a nnw trend good signal penetration through the volcanic cover is indicated by lower crustal reflections at 8 12 s which were recorded by the entire seismic survey comparison of the 2008 seismic survey with data from a previous survey indicates that the lack of reflectivity in the earlier surveys is generally representative of the subsurface geology the seismic data show that 1700 and 2900 m thick sub basins are present at the northern and southern ends of this trend but the intervening cretaceous rocks are discontinuous and relatively thin the creation of a passive roof duplex by campanian or later low angle thrusting is inferred within the thickest cretaceous strata but elsewhere faulting is likely related to eocene extension or transtension seismic reflections are also recorded from folded volcanic stratigraphy the base of the surface volcanic rocks an underlying volcaniclastic stratigraphy and intrusions projecting into a quaternary volcanic cone seismic interpretation is complemented by coincident audiofrequency magnetotelluric surveys from which faulting is inferred at offsets in a regional conductor no regionally extensive stratigraphy can be identified within the seismic data and the central nechako basin appears to be a complex network of small deformed sub basins rather than a single large basin

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

occurrence of partial and total coseismic ruptures of segmented normal fault systems insights from the central apennines italy abstract normal faulting earthquakes rarely rupture the entire extent of active normal faults and can also jump between neighbouring faults this confounds attempts to use segmentation models to define the likelihood of future rupture scenarios we attempt to study this problem comparing the offsets produced in single earthquakes with those produced by multiple earthquakes over longer timescales together with detailed studies of the structural geology we study the active normal fault system that caused the mw 6 3 2009 l aquila earthquake in central italy comparing the spatial distribution of coseismic offsets cumulative offsets that have developed since 15 3 ka and the total offsets that have accumulated since the faults initiated at 2 3 ma our findings suggest that 1 faults within a segmented fault system behave as a single interacting fault segment over time periods including multiple earthquake cycles e g 2 3 ma or 15 3ka with single earthquakes causing either partial or total ruptures of the entire system 2 an along strike bend causes throw and throw rates enhancements within the bend throughout the seismic history of the fault system we discuss the synchronised and geometrically controlled activity rates on these faults in terms of the propensity for floating earthquakes multi fault earthquakes and seismic hazard

full waveform tomography for lithospheric imaging results from a blind test in a realistic crustal model summary a comprehensive validation of 2 d frequency domain acoustic wave equation tomography was undertaken in a blind test using third party realistic elastic wave equation data the synthetic 2 d wide angle seismic data were provided prior to a recent workshop on the methods of controlled source seismology the true model was not revealed to the authors until after the presentation of our waveform tomography results the original model was specified on a detailed grid with variable p wave velocity s wave velocity density and viscoelastic q factor structure designed to simulate a section of continental crust 250 km long and 40 km deep synthetic vertical and horizontal component data were available for 51 shot locations spaced every 5 km recorded at 2779 receivers spaced every 90 m evenly spread along the surface of the model the data contained energy from 0 2 to 15 hz waveform tomography a combination of traveltime tomography and 2 d waveform inversion of the early arrivals of the seismic waveforms was used to recover crustal p velocity structure from the vertical component data using data from 51 sources 1390 receivers and frequencies between 0 8 and 7 0 hz the waveform tomography result contained apparent structure at wavelength scale resolution that was not evident on the traveltime tomography result the predicted acoustic waveforms in the final result matched the original elastic data to a high degree of accuracy during the workshop the exact model was revealed over much of the model the waveform tomography results provided a good correspondence with the true model from large to intermediate wavelength scales with a resolution limit on the order of 1 km a significant near surface low velocity zone invisible to traveltime methods was correctly recovered the results also provided a high resolution image of the complex structure of the entire crust and the depth and nature of the crust mantle transition some inaccuracies were observed near the edges of the images due to the limited ray coverage inherent to the footprint of the survey geometry several aspects of the waveform tomography strategy were critical to the success of the acoustic method with realistic synthetic viscoelastic data i the accuracy of the starting model from traveltime tomography ii implementation in the frequency domain iii the use of complex valued frequencies to effect time damping of the data residuals iv the selection of a suitable subset of data and data frequencies v progressive inversion of low to high frequency components of the data vi initial pre inversion matching of the amplitudes between observed and modelled data and vii sufficient preconditioning of both the data and the update images combined these strategies were effectively equivalent to a multiscale approach that mitigated the non linearity of the seismic inverse problem during the inversion we carried out repeated forward modelling to ensure our modelled waveforms matched the observed data as closely as possible in both frequency and time domains the synthetic data set used in this paper provides a benchmark for future testing of modelling inversion and imaging algorithms for wide angle lithospheric imaging

waveform tomography of field vibroseis data using an approximate 2d geometry leads to improved velocity models waveform tomography a combination of traveltime tomography or inversion and waveform inversion is applied to vibroseis first arrival data to generate an interpretable model of p wave velocity for a site in the nechako basin south central british columbia canada we use constrained 3d traveltime inversion followed by 2d full waveform inversion to process long offset 14 4 km first arrival refraction waveforms resulting in a velocity model of significantly higher detail than a conventional refraction statics model generated for a processing workflow the crooked line acquisition of the data set makes 2d full waveform inversion difficult thus a procedure that improves the tractability of waveform tomography processing of vibroseis data recorded on crooked roads is developed to generate a near surface 2 km velocity model for the study area the data waveforms are first static corrected using a time shift determined by 3d raytracing which accounts for the crossline offsets produced by the crooke

the evolution of the gulf of corinth greece an aftershock study of the 1981 earthquakes summary a preliminary study of the aftershocks of three earthquakes that occurred near to corinth greece in 1981 is combined with observations of the morphology and faulting to understand the evolution of the eastern gulf of corinth the well located aftershocks form a zone 60km long and 20km wide they do not lie on the main fault planes and are mostly located between the north dipping faulting on which the first two earthquakes occurred and the south dipping faulting associated with the third event a cluster of aftershocks also lies in the footwall of the eastern end of the south dipping fault of the third event morphologically it is observed that in the evolution of the eastern gulf of corinth antithetic faulting apparently predates the appearance of the main faulting at the surface this evolution can be explained by motion on a deep seated shallow angle aseismic normal fault a model based on such a fault also accounts for the aftershock distribution of the 1981 earthquakes

geometry kinematics and rates of deformation in a normal fault segment boundary central greece the geometry kinematics and rates of deformation within a fault segment boundary between the ends of two major active normal fault segments have been investigated through examination of a faulted 126 ka marine terrace slip vector azimuths defined by striations on the faults indicate n s extension on c e w faults sub parallel to those from earthquake focal mechanisms together with significant and contemporaneous e w extension on c n s faults summed rates of e w extension along a c 550 m transect 0 17 mm yr are comparable with those for n s extension 0 20 mm yr along a c 350 m transect our observations show that distributed non plane strain extension occurs in fault segment boundaries and this should be noted when studying fault tip fracture toughness and regional deformation rates

detecting near surface objects with seismic waveform tomography three shallow high velocity rubble filled targets are imaged using waveform tomography in an engineering scale clay embankment at seven sisters falls manitoba canada to locate targets buried at approximately 7 m as a blind test of geophysical imaging methods previous studies use near offset reflection methods to image the targets however this test uses waveform tomography of the long offset refracted arrivals to image p velocity and seismic attenuation the targets are invisible to standard traveltime tomography using weight drop data with frequencies of 20 150 hz the subwavelength targets are resolved in the velocity images and complementary images of seismic q are produced the interpreted target locations are consistent with limited survey information from the embankment construction multiple quality control efforts paired with a very good fit between model and observed data indicate the reliability of the results