correlations of earthquake focal mechanisms summary we performed a statistical analysis of the harvard catalogue of seismic moment tensor solutions we investigated the distribution of hypocentres on focal spheres of earthquakes the hypocentres are concentrated along fault planes the hypocentre distribution does not significantly differ for earthquakes in different depth ranges to study the rotation of focal mechanisms we have solved an inverse problem of a 3 d rotation of double couple earthquake sources i e for each pair of focal mechanisms we find all four 3 d rotations which rotate one mechanism into another the stochastic disorientation of focal mechanisms is well approximated by the rotational cauchy distribution which has previously been identified through theoretical arguments and simulations as the result of stress perturbations caused by random defects in the medium the cauchy distribution is characterized by one parameter k k 0 means no rotations and k 0 5 corresponds to approximately random rotation for earthquake focal mechanisms the value of k is between 0 05 and 0 1 in a fault zone and it increases with distance between pairs of events in directions other than a fault plane k reaches the value 0 5 the cauchy distribution is then close to completely random rotations although k increases slowly with depth in general disorientations of focal mechanisms in various depth ranges display the same dependence therefore we can conclude that deep earthquakes are controlled by the same stress interaction regime as shallow events the results of these measurements made us question the suitability of some terms and models that are commonly used in the theory of an earthquake source for example we argued that tectonic earthquakes rupture rock material which has large scale defects or faults comparable in size with tectonic blocks in which they originate properties of the rocks should be significantly different from those of regular materials where the size of defects is typically much smaller than the scale of interest these properties should strongly depend on the geometry location and orientation of major defects

use of terrestrial laser scanning tls for monitoring and modelling of geomorphic processes and phenomena at a small and medium spatial scale in polar environment scott river spitsbergen abstract the application of terrestrial laser scanning tls for precise modelling of land relief and quantitative estimation of spatial and temporal transformations can contribute to better understanding of catchment forming processes experimental field measurements utilising the 3d laser scanning technology were carried out within the scott river catchment located in the nw part of the wedel jarlsberg land spitsbergen the measurements concerned the glacier free part of the scott river valley floor with a length of 3 5 km and width from 0 3 to 1 5 km and were conducted with a state of the art medium range stationary laser scanner a leica scan station c10 a complex set of measurements of the valley floor were carried out from 86 measurement sites interrelated by the application of 82 common target points during scanning from 5 to 19 million measurements were performed at each of the sites and a point cloud constituting a model space was obtained by merging individual model spaces a digital surface model dsm of the scott river valley was obtained with a co registration error not exceeding 9 mm the accuracy of the model permitted precise measurements of dimensions of landforms of varied scales on the main valley floor and slopes and in selected sub catchments the analyses verified the efficiency of the measurement system in polar meteorological conditions of spitsbergen in mid summer

mechanics of low stress forearcs nankai and cascadia the nankai and cascadia subduction zones have low stress forearcs where the margin normal horizontal compressive stress is similar to or less than the vertical stress except in the accretionary prisms in the absence of active back arc spreading the forearc margin normal stress is controlled mainly by the total shear force along the subduction fault or the plate coupling force and the gravitational force the plate coupling force creates compression and the gravitational force in the presence of margin topography creates lateral tension we give a simple expression that relates the forearc stress to topography and average fault strength with the latter represented by an effective coefficient of friction we also use a finite element model of two converging plates in frictional contact to model the forearc stresses the analyses indicate that a low stress forearc requires not only the subduction fault to be very weak but also the mechanically coupled fault area to be narrow in the downdip direction and shallow in depth for nankai and cascadia where the coupled fault areas are narrow and shallow because of the young and hot subducting plates is about 0 05 or less and in any case less than 0 09 the low fault strength is probably not a unique property of low stress forearcs since the same low values combined with wider and deeper coupled areas can be shown to create large margin normal compression in addition there does not seem to be any relation between subduction earthquake magnitudes and plate coupling forces great earthquakes occur at subduction zones having low stress forearcs such as nankai and cascadia

slow diffusive fault slip propagation following the 6 april 2009 l aquila earthquake italy 1 two laser strainmeters that operate at 1400 m depth about 20 km ne of the epicenter of the 6 april 2009 magnitude 6 3 l aquila italy earthquake have produced a clear record of postseismic strain here we show the results from the analysis of the data related to the first few days after the event strain after about 1 5 days is fully consistent with afterslip on a stationary region of the earthquake causative fault the preceding few hour long transient whose seismic moment history is quasi exponential is fully consistent with unilateral diffusive slip propagation toward the shallower part of the same fault the propagation path ends where later afterslip probably occurred slip propagation similar to heat diffusion has been suggested to explain the observed scaling law between amplitude and duration of slow earthquakes here we give the first observational evidence of the role and details of slow rupture propagation

trace fossils biology and taphonomy 1990 special topics in palaeontology 3 280 pp e17 95 pbk e40 00 hbk unwin hyman london isbn 004445 6867 pbk 3035 hbk

stress strain paradox plate coupling and forearc seismicity at the cascadia and nankai subduction zones abstract in the continental forearcs of the cascadia and nankai subduction zones geodetic strain measurements indicate crustal contraction in the direction of plate convergence nearly margin normal but earthquake focal mechanisms and other stress indicators show maximum compression along strike margin parallel it is evident that the geodetic strain signals reflect the temporal fluctuations of elastic stress associated with subduction earthquake cycles not the absolute stresses the absolute margin normal stress is not only much less than the margin parallel stress but also no greater than the lithostatic value indicating a very weak subduction thrust fault weak subduction faults are also consistent with geothermal data which require very low frictional heating along the faults great subduction earthquakes occur at very low shear stresses and cause small perturbations to the forearc stress regime because these small elastic stress perturbations are relatively fast they give large strain rates that are detected by geodetic measurements the present nearly margin normal contraction in both places is due to the locking of the subduction fault and the consequent increase in elastic stress in the direction of plate convergence with the margin parallel compression being dominant the small increase in margin normal stress may change the forearc seismicity in cascadia from a mixture of thrust and strike slip types into mainly thrust before the next great subduction earthquake in nankai the change should be from strike slip to quiescence as observed in the nankai forearc prior to the 1944 1946 great subduction earthquakes

ichnology of a paleopolar river dominated shallow marine deltaic succession in the mackellar sea the mackellar formation lower permian central transantarctic mountains antarctica abstract the lower permian mackellar formation in the beardmore glacier area of the central transantarctic mountains antarctica was deposited between 80 and 85 s paleolatitude previous studies suggest that mackellar formation strata were deposited in either a large glacial lake or inland sea our study identified 30 ichnogenera from turnabout ridge and buckley island of which 1 none are exclusively freshwater forms 2 20 ichnogenera are found in freshwater brackish and marine settings and 3 10 ichnogenera are exclusively found in marine settings combining ichnologic evidence with sedimentologic observations suggests that the mackellar formation was deposited in a river dominated delta in a fully marine to brackish marine setting trace fossil associations are grouped into the arenicolites phycodes lingulichnus arenicolites planolites kouphichnium phycodes teichichnus arenicolites and planolites teichichnus phycodes ichnocoenoses of a mixed skolithos cruziana ichnofacies these associations are characteristic of epi and endobenthic worms arthropods and mollusks with the vast majority of the traces being diminutive in diameter and length and exhibit shallow 10 mm penetration depths these ichnocoenoses occur in paleoenvironments that include the prodelta distal to proximal delta front including mouth bars and subaqueous terminal distributary channels the diminutive morphology shallow penetration depth low bed ichnodiversity high overall ichnodiversity and sedimentologic characteristics are indicative of benthic organisms in a marine deltaic environment with short lived communities composed of small bodied organisms stressed by high freshwater input and high sedimentation rates

finite fault inversion of dinsar coseismic displacement of the 2009 l aquila earthquake central italy 1 we define the geometric and kinematic characteristics of the fault activated during the mw 6 3 6 april 2009 l aquila earthquake from the modeling of envisat and cosmo skymed the first ever x band interferogram inverted for a coseismic dislocation study dinsar interferograms our best fit solution for the main shock is represented by a normal fault 16 km long and 12 km wide with a small right lateral component dipping 47 sw with a maximum slip of 90 cm although the seismic dislocation probably ended at 1 km depth the updip projection of the fault plane corresponds to the northern segment of the mapped paganica s demetrio fault where alignment of surface breaks was observed in the field the absence of this fault in existing seismic source catalogues suggests that an improved approach involving detailed surface and subsurface geological and geophysical investigations is needed for a better assessment of the seismic hazard at the local scale

a viscoelastic coupling model for the cyclic deformation due to periodically repeated earthquakes at subduction zones vertical displacements due to periodic reverse faulting events in an elastic plate overlying a viscoelastic maxwell half space are obtained and compared with the observed deformation cycle coseismic strain release postseismic transients interseismic strain accumulation from japan the viscoelastic effects including the influence of buoyant restoring forces are obtained using the method developed by rundle and plate convergence and strain accumulation are incorporated following the procedure suggested by savage the resulting deformation cycle is compared with that of an analogous elastic half space dislocation model in which postearthquake effects are due to transient aseismic slip below the coseismic fault cyclic deformation is similar but not identical for the two models and observations from southwest japan suggest the superiority of the viscoelastic coupling model in particular inclusion of the effects of steady state flow in the asthenosphere overcomes a defect of the elastic half space model and results in agreement with the observed interseismic movement pattern several aspects of the postseismic deformation its landward migration and its transition to the interseismic phase of the cycle are explained as well but the short duration of near trench transients relative to those observed farther inland is not matched the success of a buried slip model in explaining early postseismic near trench movements and asthenospheric flow in accounting for cumulative postearthquake transient motions suggests the existence of a transition zone between lithosphere and asthenosphere whose behavior is brittle elastic in the short term and ductile for longer term deformation and such a modification may reconcile remaining discordant observations however reasonable variations in coupling model parameters cannot account for observed differences in the deformation cycle in other parts of japan and these regional differences remain unexplained

resolving vertical and east west horizontal motion from differential interferometric synthetic aperture radar the l aquila earthquake 1 analysis of surface coseismic displacement has already been obtained for the 6 april 2009 l aquila central italy earthquake from differential interferometric synthetic aperture radar dinsar data working jointly on ascending and descending dinsar data makes for a step forward with respect to published preliminary estimates we process data in order to retrieve a continuous displacement pattern both in the vertical and horizontal directions the latter being limited to the eastward component because of the low sensibility of the sar images used to resolve northward motion our analysis provides new insights on the horizontal component of displacement obtaining a clear picture of eastward displacement patterns over the epicentral area this result is noteworthy as until now little information has been available on horizontal displacement following normal fault events in the central apennines umbria marche 1997 and l aquila 2009 given the lack of dense gps networks the only available source of horizontal displacement data in this area inverted fault characteristics from such data also show noteworthy differences compared to previous studies localizing the paganica fault as the causative fault for the earthquake

a physical mechanism for temporal variation in seismicity in southwest japan related to the great interplate earthquakes along the nankai trough abstract a significant correlation has been reported between the intraplate inland and the great interplate earthquakes in southwest japan based on historical earthquake data since 868 the frequency of intraplate earthquakes is high for several decades before and up to a decade after great interplate earthquakes to explain the correlation we treated two types of interaction between the inland faults and the plate boundary a in which the stress changes caused by great interplate earthquakes affect the occurrence of intraplate earthquakes and b in which the stress changes caused by intraplate earthquakes trigger other intraplate earthquakes and great interplate earthquakes to simulate the sequences of these earthquakes we calculated the static stress changes resulting from large intraplate and great interplate earthquakes and also estimate the rate of increase in tectonic stress on the faults and the plate boundary the estimated rates of increase here are smaller than those used in previous studies thus in our models stress changes could more strongly affect the seismicity than previously considered we simulated the earthquake sequences for our models in four cases i with no interaction among the inland faults in southwest japan and the plate boundary along the nankai trough ii with stress changes on the inland faults caused only by great interplate earthquakes iii with stress changes on the plate boundary caused only by large intraplate earthquakes and iv with stress changes both on the inland faults and on the plate boundary caused by large intraplate earthquakes the simulated time series in case i of course shows no correlation between intraplate and great interplate earthquakes those in cases iii and iv also show no significant correlation only the time series of intraplate earthquakes in case ii shows a temporal variation similar to that of the real intraplate earthquakes before and after the great interplate earthquakes we examined statistically the similarity between the simulated time series and the real earthquake data about 40 of the time series in case ii are significantly similar although in the other three cases less than 5 of the time series are understanding of the effects of stress changes on the inland faults caused by the great interplate earthquakes along the nankai trough is essential to explain the temporal variation in seismicity in southwest japan before and after the great interplate earthquakes

implications of trace fossil assemblages from late paleozoic glaciomarine talchir formation raniganj basin india abstract the trace fossil assemblages of the ice marginal shallow marine sediments of the talchir formation permo carboniferous raniganj basin india record the adverse effect of extreme climatic conditions on biota the glaciomarine talchir succession starts with glacial sediments near the base and gradually passes to storm laid shallow marine sediments up section the fine grained storm sediments host abundant trace fossils although the studied ichnites characteristically show marginal marine affinity the ichnodiversity and bioturbation intensity suggest a lower than normal shallow marine trace fossil population further endobenthic annelids worms and crustaceans are identified as dominant trace makers sediment reworking near the ice grounding line extremely cold climate high energy storm sedimentation and anomalous water chemistry hindered organic colonization during the early phases of talchir sedimentation later climatic amelioration ushered in a favourable ambience for the benthic community to colonize within or beyond the storm weather wave base in the outer shoreface shelf environment fluctuating storm energy dominantly controlled the availability and influence of other environmental stimuli in the environment and thus governed the distribution abundance and association of the studied ichnites however impoverished ichnodiversity sporadic distribution of the traces overall smaller burrow dimensions absence of body fossils dominance of worms and annelids as trace makers all indicate a stressed environmental condition induced by cold climate and lowered marine salinity due to influx of glacier melt out freshwater during climatic amelioration in the permo carboniferous ice marginal sea

active normal faulting during the 1997 seismic sequence in colfiorito umbria did slip propagate to the surface in order to determine whether slip during an earthquake on the 26th september 1997 propagated to the surface structural data have been collected along a bedrock fault scarp in umbria italy these collected data are used to investigate the relationship between the throw associated with a debated surface rupture observed as a pale unweathered stripe at the base of the bedrock fault scarp and the strike dip and slip vector previous studies have suggested that the surface rupture was produced either by primary surface slip or secondary compaction of hangingwall sediments some authors favour the latter because sparse surface fault dip measurements do not match nodal plane dips at depth it is demonstrated herein that the strike dip and height of the surface rupture represented by a pale unweathered stripe at the base of the bedrock scarp shows a systematic relationship with respect to the geometry and kinematics of faulting in the bedrock the strike and dip co vary and the throw is greatest where the strike is oblique to the slip vector azimuth where the highest dip values are recorded this implies that the throw values vary to accommodate spatial variation in the strike and dip of the fault across fault plane corrugations a feature that is predicted by theory describing conservation of strain along faults but not by compaction furthermore published earthquake locations and reported fault dips are consistent with the analysed surface scarps when natural variation for surface dips and uncertainty for nodal plane dips at depth are taken into account this implies that the fresh stripe is indeed a primary coseismic surface rupture whose slip is connected to the seismogenic fault at depth we discuss how this knowledge of the locations and geometry of the active faults can be used as an input for seismic hazard assessment

post seismic relaxation following the 2009 april 6 l aquila italy earthquake revealed by the mass position of a broad band seismometer summary post seismic relaxation is known to occur after large or moderate earthquakes on time scales ranging from days to years or even decades in general long term deformation following seismic events has been detected by means of standard geodetic measurements although seismic instruments are only used to estimate short timescale transient processes albeit inertial seismic sensors are also sensitive to rotation around their sensitive axes the recording of very slow inclination of the ground surface at their standard output channels is practically impossible because of their design characteristics however modern force balance broad band seismometers provide the possibility to detect and measure slow surface inclination through the analysis of the mass position signal this output channel represents the integral of the broad band velocity and is generally considered only for state of health diagnostics in fact the analysis of mass position data recorded at the time of the 2009 april 6 l aquila mw 6 3 earthquake by a closely located sts 2 seismometer evidenced the occurrence of a very low frequency signal starting right at the time of the seismic event this waveform is only visible on the horizontal components and is not related to the usual drift coupled with the temperature changes this analysis suggests that the observed signal is to be ascribed to slowly developing ground inclination at the station site caused by post seismic relaxation following the main shock the observed tilt reached 1 7 10 5 rad in about 2 months this estimate is in very good agreement with the geodetic observations giving comparable tilt magnitude and direction at the same site this study represents the first seismic analysis ever for the mass position signal suggesting useful applications for usually neglected data

quantitative description of induced seismic activity before and after the 2011 tohoku oki earthquake by nonstationary etas models 1 the epidemic type aftershock sequence etas model is extended for application to nonstationary seismic activity including transient swarm activity or seismicity anomalies in a seismogenic region the time dependent rates of both background seismicity and aftershock productivity in the etas model are optimally estimated from hypocenter data these rates can provide quantitative evidence for abrupt or gradual changes in shear stress and or fault strength due to aseismic transient causes such as triggering by remote earthquakes slow slips or fluid intrusions within the region this extended model is applied to data sets from several seismic events including swarms that were induced by the m9 0 tohoku oki earthquake of 2011

unravelling the complexity of apenninic extensional fault systems a review of the 2009 l aquila earthquake central apennines italy the 2009 l aquila sequence activated a normal fault system 50 km long in the central apennines composed of two main nw trending faults 12 16 km long the main high angle l aquila segment and the campotosto listric fault the mw 6 1 l aquila mainshock nucleated on the paganica fault at a depth of 8 6 km and cut through the upper crust producing coseismic surface slip of up to 10 cm observed along a strike length of 13 km analysis of historical seismicity and data collected in paleo seismological trenches suggest that this event filled a 500 year gap in contrast the blind campotosto listric fault is composed of different fault segments displaying abrupt changes in dip at a depth where major events nucleate suggesting a rheological and geometrical control on stress concentration a foreshock sequence that started around 4 months before the l aquila mainshock activated the deepest portion of the paganica fault and marked the onset of large variations in elastic properties of the crustal volume the variations have been modelled in terms of dilatancy and diffusion processes corroborating the hypothesis that fluids play a key role in the nucleation process of extensional faults in the crust

volcanic tephra bed formation and condensation processes a review and examination from devonian stratigraphic sequences abstractthe formation and preservation of airfall volcanogenic tephras is the result of various interacting factors explanations of the depositional history of individual tephra beds lie along a spectrum between two end member models of a primary single event and a complex depositional history nonrecognition of the history of a tephra bed may lead to errors in geochronology correlation and interpretation of the record of explosive volcanism in sedimentary successions increased understanding of sequence stratigraphic principles and condensation processes favors the model of tephras with a complex depositional history this is supported by studies that indicate many tephras in the rock record result from amalgamation and or reworking in the depositional environment a prediction of increased tephra bed formation preservation within transgressive systems tracts due to condensation processes is tested through 11 lochkovian to eifelian lower to lower middle devonian depositional sequences the character

k bentonites volcanic ash preservation and implications for early to middle devonian volcanism in the acadian orogen eastern north america lower to middle devonian marine strata in the appalachian foreland basin feature up to 80 or more thin k bentonites that represent ancient volcanic ashes the time vs space distribution of k bentonites through the lochkovian to eifelian stages representing 30 m y shows a distinct pattern of clustered multiple beds several scattered beds and thick intervals with no k bentonites four clusters of 7 to 15 individual closely spaced layers occur in the middle lochkovian bald hill k bentonites kalkberg new scotland formations late pragian or early emsian sprout brook k bentonites esopus formation and early eifelian two clusters the tioga middle coarse zone and tioga a g k bentonites onondaga formation detailed examination of these devonian k bentonites shows that in many cases they do not represent a single eruption multilayered beds fossil layers within beds authigenic minerals e g glauconite and phosphate nodules subjacent hardgrounds and an irregular distribution of beds through space and time raise questions about the depositional history and preservation potential of volcanic ash in marine environments and the degree to which the beds represent a primary record of volcanism these and other lines of evidence indicate that postdepositional physical biological and geochemical processes e g sedimentation rate event and background physical processes burrowing have modified the primary record of these water laid ash fall events these factors may lead to preservation of primary ash deposits or to their resedimentation and or partial to complete mixing with background sediments the preservation potential and resulting distribution of the devonian k bentonites can be analyzed across a spectrum of preservational magnafacies in this paper i present a model of ash preservation the model incorporates environmentally related physical biological and chemical processes active in epicontinental seas and marine foreland basins conclusions based on the model indicate that the middle lochkovian early emsian and early eifelian were times of peak volcanic activity in eastern north america related to times of increased tectonism in the acadian orogen

the stress field induced from the occurrence of the 1944 tonankai and the 1946 nankaido earthquakes and their relation to impending earthquakes abstract we investigate the changes of tectonic stress in the crust and upper mantle beneath southwest japan associated with the occurrence of the 1944 tonankai and the 1946 nankaido earthquakes and their possible relation to impending earthquakes by using a three dimensional finite element method we construct a three dimensional model incorporating the assumed fault planes of these earthquakes the calculated results indicate that the temporal changes in the direction of the compressive stress from n s to e w beneath the kii channel and the eastern part of shikoku observed after the two earthquakes may be attributed only to the seaward rebound of the hanging wall side of the assumed faults for these earthquakes the temporal change appears to have returned to the original stage after 20 yr indicating that the coseismic disturbance of the stress field could persist for several years the two earthquakes may have caused a local stress drop of

microstructural evidence for seismic and aseismic slips along clay bearing carbonate faults in this multi methodological study microstructural observations of fault rocks are combined with micromechanical property analyses contact resonance atomic force microscopy cr afm and with rotary friction experiments shiva apparatus to find evidence of seismic to aseismic slip and understand the nanoscale rheology of clay bearing carbonate hosted faults fluidized structures truncated clasts pores and vesicles and phyllosilicate nano sized spherules and tubes suggest fast deformation events occurred during seismic slip whereas clay assisted pressure solution processes clumped clasts foliation surfaces and mantled clasts indicate slow deformation events occurred during postseismic interseismic periods cr afm measurements show that the occurrence of 5 wt of clay within the carbonate hosted gouges can significantly reduce the fault core stiffness at nanoscale in addition during high velocity friction experiments simulating seismic slip conditions the presence of ultra thin phyllosilicate bearing 3 wt layers within calcite gouges as those observed in the natural fault show faster dynamic weakening than that of pure calcite gouges the weak behavior of such layers could facilitate the upward propagation of seismic slip during earthquakes thus possibly enhancing surface faulting microstructural observations and experimental evidence fit some well known geophysical and geodetic observations on the short to long term mechanical behavior of faults such as post seismic interseismic aseismic creep interseismic fault locking and seismic slip propagation up to the earth s surface

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

a fault model of the 1946 nankaido earthquake derived from tsunami data abstract a fault model of the 1946 nankaido earthquake m 8 2 is determined by the use of tsunami records of uwajima shimotsu and hososhima which were located within or near the area of major coseismic crustal deformation synthetic tsunamis computed for various fault models are matched with the observed tsunamis to determine the fault parameters a low angle thrust model slightly revised from a previous model by ando is consistent with the observed tsunamis the duration of faulting is constrained as less than 10 min based upon the tsunami the fault is divided into an eastern and a western segment corresponding to areas associated with and without aftershocks respectively the fault area and dislocation for the western segment are 150 70 km2 and 6 m and those for the eastern segment are 150 70 km2 and 3 m respectively the total seismic moment is 4 7 1028 dyn cm significantly smaller than that obtained from a geodetic model by fitch and scholz but still larger than that of the seismic model by kanamori the discrepancy in seismic moment between the seismic and the present models ran2 could be interpreted in terms of a slow dislocation on the fault but this interpretation does not match the seismic intensity distribution and damage pattern and the slow slip model for the nankaido earthquake is rejected the discrepancy between the two seismic moments is considered insignificant within error involved in data and modeling assumptions if the revised geodetic model ran2 is modified the seismic moment required to explain the observed tsunamis would be reduced further by 30 if we consider the uncertainties involved in the fault model of kanamori and the fault finiteness effect affecting the amplitude of seismic waves the seismic moment required to interpret the seismic wave data could be increased possibly being more than twice that of kanamori thus the two seismic moments from the different data sets could be close to each other within allowable tolerance this implies that the rise time of the nankaido earthquake was short enough to generate short period seismic waves from both the western and the eastern fault segments

production of subtidal tubular and surficial tempestites by hurricane kate caicos platform british west indies abstract storm infilling of deep open callianassa burrows with molluscan to peloidal packstone was the dominant style of preservable sedimentation produced by the passage of hurricane kate across caicos platform british west indies on 18 november 1985 this moderate hurricane was the first to affect an actively studied portion of the carbonate platform environments of the south florida bahama region in 19 years a time during which many of our concepts of storm sedimentation have evolved prior to hurricane kate much of the shallow platform interior peloidal packstone to grapestone grainstone had a sparse seagrass cover and a highly irregular bottom caused by abundant callianassa mounds hurricane kate flattened the mounded bottom of the platform interior and caused minor smothering and erosion of the seagrass beds a thin surficial tempestite though deposited over much of the platform was difficult to identify because it lacked a coarse base instead much of the reworked surface sediment poured down the large callianassa burrow entrances and filled the vast burrow networks with either a coarse molluscan packstone or peloidal skeletal packstone storm burrow filling tubular tempestites effectively removed the coarse fraction from contributing to a surficial storm layer ten percent of the upper 75 cm of platform interior sediment consists of tubular tempestites from hurricane kate

early to mid cretaceous tectonics and unconformities of the wessex basin southern england sediment distribution patterns time subsidence plots seismic data and outcrop analysis of the lower cretaceous ryazanian albian of the wessex basin southern england suggest that a number of unconformable horizons exist and that there is no single late cimmerian unconformity surface a tectonic change from areally restricted deposition in the weald and channel sub basins to extensive sedimentation across the whole of southern england began in the mid aptian this change ended with transgression of basement highs in the early albian of the dorset area and later albian of the devon and london platform basin margin areas its onset can be linked to the austrian tectonic phase of europe the onset of marine deposition in the aptian is coincident with periodic transgression of the margins of the wessex basin throughout the aptian albian mid late aptian and early mid aibian transgressions were preceded by periods of erosion the aptian albian lower greensand is characterized by transgressive regressive phases suggesting a short term controlling process third order eustatic changes or intra plate mechanisms tectonic changes in the mid aptian include uplift followed by widespread subsidence this change coincides with a time of plate reorganization in the european and north atlantic areas

partitioned off fault deformation in the 2016 norcia earthquake captured by differential terrestrial laser scanning field measurements of co seismic fault slip often differ from surface slip models derived from satellite geodesy quantifying these differences is challenging as many geodetic techniques inadequately image near fault deformation we use an iterative closest point icp algorithm to difference pre and post earthquake terrestrial laser scanning tls point clouds to reveal cm scale patterns of surface deformation caused by shallow fault slip in the 2016 mw 6 6 norcia central italy earthquake tls offsets are constant along the fault and match average field measurements 84 of vertical displacement occurs on a discrete fault zone with 16 of deformation distributed across a narrow zone 4 m wide in contrast horizontal deformation is distributed over an 8 m wide zone with c 50 of extension accommodated as off fault deformation ofd the cm scale observation of deformation shows that horizontal and vertical co seismic ofd is partitioned in this case ofd is dominated by horizontal deformation

insar data as a field guide for mapping minor earthquake surface ruptures ground displacements along the paganica fault during the 6 april 2009 l aquila earthquake 1 on 6 april 2009 a moderate earthquake mw 6 3 ml 5 8 struck the abruzzo region in central italy causing more than 300 fatalities and heavy damage to l aquila and surrounding villages coseismic surface effects have been thoroughly documented by timely field surveys as well as by remote sensing analyses of satellite images the outstanding quality of geological seismological geodetic and interferometric synthetic aperture radar insar information arguably represents the best ever data set made available immediately after a moderate seismic event based on this data set we aim at testing the capability of coupled geological and insar data to map surface faulting patterns associated with moderate earthquakes coseismic ground ruptures have been mapped at a scale of 1 500 in the whole epicentral area traces of surface ruptures have been inferred from linear phase discontinuities identified in the interferogram a very good agreement between the two methods resulted in the characterization of the main surface rupture along the paganica fault the same approach applied to ground ruptures hypothesized along other capable fault segments provided more questionable results thus the combined field and insar approach appeared useful for detecting continuous surface ruptures exceeding 1 km in length and showing displacements greater than a few centimeters these are the typical faulting parameters for moderate earthquakes 6 0 mw 6 5 in central apennines for continuous ground cracks shorter than a few hundred meters and or that show displacements smaller than 1 2 cm the described approach may be less helpful most probably due to the limited resolution of the data

proximal distal ichnofabric changes in a siliciclastic shelf early pliocene guadalquivir basin southwest spain abstract the lower pliocene deposits cropping out along the atlantic coast of cadiz in the conil cabo roche area formed on a shelf gently deepening towards the w nw up to five types of facies can be recognized distributed in belts from proximal to distal parts of the shelf 1 coarse grained sandstone with trough cross stratification facies on the most proximal parts of the shelf inner shelf deposits 2 medium grained sandstone with low angle planar cross stratification facies deposited in a more distal position due to storm currents transporting sediment offshore this facies intercalates with the previous trough cross bedded sandstone 3 massive fine grained sandstone and siltstone facies laterally and vertically related with the previous facies type and representing sediments formed in the middle shelf close to the storm wave base 4 tabular sandstone bed facies corresponding to storm bed deposits intercalated within the two previous facies 5 greenish bluish shale facies accumulated on the outer shelf below storm wave base three ichnofabrics associated with these facies are recognized 1 the two cross bedded facies are dominated by a macaronichnus ichnofabric characterized by macaronichnus and bichordites traces that represent colonization of a shifting sandy substrate by polychaetes macaronichnus tracemakers and by sea urchins bichordites producers 2 a rosselia ichnofabric consisting of vertical traces of rosselia cross cutting macaronichnus characterizes the interval of massive fine grained sandstone and silt facies and interbedded tabular sandstones this ichnofabric formed under high sedimentation rates with rosselia traces exhibiting stacked patterns that indicate vertical readjustment following deposition 3 massive fine grained sandstone and silt facies are distinguished by a cylindrichnus ichnofabric this fabric was produced by the activity of a moderately diverse community dominated by sessile burrow dwelling probably superficial detritus feeding polychaetes rosselia and cylindrichnus tracemakers and vagile deposit feeding polychaetes planolites producers in addition infaunal deposit detritus feeders producing spreiten structures teichichnus are found in distal areas pervasive indistinct mottling of the sediment of this facies was probably due to the activity of very shallow burrowers in the uppermost sediment tiers this proximal distal replacement of ichnofabrics reflects the change of benthic communities across the shelf this distribution does not fit the traditional seilacherian ichnofacies model for soft ground shallow marine settings in which proximal vertical dwelling burrows of the skolithos ichnofacies dominate high energy environments in the pliocene of cadiz shallow tier burrows of deposit detritus feeders characterize the high energy facies instead which fit better with the cruziana ichnofacies this deviation can be related with the particular palaeoenvironmental conditions thus vagile opportunistic deposit feeders colonized the dune foreset when the dunes were stable and the progradation of the structure favored the preservation of the traces

on the mechanics of earthquake afterslip we propose a model for earthquake afterslip based on rate and state variable friction laws in the model afterslip is attributed to the interaction of a velocity weakening region at depth within which earthquakes nucleate with an upper region of velocity strengthening frictional behavior the existence of this upper region is supported by independent seismologic observations and the results of laboratory friction experiments in our model afterslip is the result of relaxation of a stress perturbation within the velocity strengthening region which arises when an earthquake propagates into that region from below we derive the stress perturbation and its decay from the friction constitutive law using a simple 1 degree of freedom approximation for the elastic interaction between the fault and its surroundings this approximation is based on thickness averaged displacements and slip velocities within the velocity strengthening region which is assumed to slip as a rigid block coseismic and postseismic slip are coupled through the thickness averaged stiffness k of the velocity strengthening region we assume k to be inversely proportional to the thickness of this region which means that thicker velocity strengthening regions have a greater tendency to arrest coseismic slip we model the afterslip time histories of the 1966 parkfield and 1987 superstition hills earthquakes and relate the model parameters to physical parameters which may govern the rheologic behavior of the faults in accord with field observations our model predicts 1 that afterslip on some faults scales with the thickness of the unconsolidated sedimentary cover and 2 that proportionally more afterslip occurs for earthquakes in which coseismic surface slip is small compared with coseismic slip at depth velocity strengthening frictional behavior is to be expected for faults within poorly consolidated sediments and for those that contain significant gouge zones about 500 m within their shallow regions 3 5 km combining our results with those of recent laboratory friction studies indicates that relatively young faults with little accumulated fault gouge should exhibit little afterslip

ichnology of american chalks the selma group upper cretaceous western alabama chalk facies within the selma group most of them impure crop out only in a relatively small area of western alabama and eastern mississippi and grade laterally into calcareous terrigenous clastics body fossils and skeletal borings described in a separate paper are diverse and abundant in some units especially the impure chalks major burrow forms also distributed unequally among these units include chondrites sp cylindrichnus pustulosus n sp planolites beverleyensis skolithos sp teichichnus rectus teichichnus zigzag n sp thalassinoides paradoxicus thalassinoides suevicus trichichnus linearis zoophycos sp and mineralized burrows minor forms include palaeophycus sp rosselia spp and mantled burrows characteristic trace fossil distributions especially include the striking dominance of thalassinoides paradoxicus in chalk hardgrounds of the arcola member of the mooreville chalk and successive patterns of bioturbation in the lower unnamed member of the demopolis chalk in purer chal

microbial and meiofaunal abundance redox potential ph and shear strength profiles in deep sea pacific sediments vertical profiles of microbial and meiofaunal abundances and of redox potential ph water content and shear strength have been measured in sediment subcores from seven box cores collected in the southern central pacific and the findings have been related to potential effects on pelagic fluxes and sedimentation microbial and meiofaunal abundance decreased exponentially with sediment depth micro organisms were found throughout the depth of the core to 40 cm meiofauna were only present in the top 5 cm to 10 cm meiofaunal metazoans decreased more rapidly than foraminiferans redox potential was always positive decreased below the surface and often rose again deeper in the sediment ph showed no clear cut trend with depth shear strength increased with sediment depth and showed occasional anomalous fluctuations water content decreased progressively downwards with the widest scatter in the top 5 10 cm the most important implications of these results for the water column above are likely to be biologically mediated organic mineralization and nutrient regeneration into the water column and biodeposition of heavy metals and the binding of particulates at and above the sediment water interface by extracellular polymeric material which will in turn lead to differential patterns of sedimentation

thermal constraints on the seismogenic portion of the southwestern japan subduction thrust for coastal cities an important factor in earthquake hazard from subduction zone earthquakes is the landward extent of the seismogenic portion of the subduction thrust fault in this study we test the hypothesis that the maximum downdip extent is defined by a critical temperature we have developed a transient thermal model for the nankai subduction zone of southwest japan to allow comparison of the thermally estimated downdip extent of the seismogenic zone with that from 1 seismicity and tsunami data for two great subduction earthquakes 2 the coseismic faulting extent of these events estimated from geodetic deformation data and 3 the interseismic locked zone determined from interseismic geodetic data the nankai margin has extensive heat flow and heat production data to control thermal models and thus crustal temperatures it has earthquake tsunami and geodetic data that constrain the coseismic rupture portion of the subduction thrust fault for past great earthquakes and the portion of the thrust fault that is locked and storing interseismic elastic strain on the nankaido margin off shikoku island the thermal model indicates that a temperature of 350 c taken to be the limit for seismic initiation from laboratory and field data is reached on the subduction thrust fault 150 km from the trench a transition zone into which rupture may extend with decreasing offset taken to be 450 c extends an additional 45 km downdip the thermal model results are in excellent agreement with the maximum downdip extent of coseismic displacement for the 1946 nankaido ms 8 2 earthquake off shikoku island and with the downdip extent of the present locked zone in the region of the 1944 tonankai ms 8 2 earthquake to the northeast the subduction angle is much steeper and the thermal models indicate a narrower downdip seismogenic extent the seismogenic locked zone from earthquake and geodetic data is also narrower thus our analysis of the southwest japan margin indicates that all three constraints on the downdip extent of the seismogenic zone thermal coseismic and interseismic geodetic data are in general agreement the study also supports the hypothesis that the seismogenic portion of subduction thrust faults is limited primarily by temperature the thermal control implies that subduction thrust faults with shallow dip have wider seismogenic zones compared to those with steep dip the subducting plate age and thus heat flow and the thickness of the insulating sediments on the incoming plate are also very important to the thermal regime and thus to the seismogenic width the relation of the maximum seismic rupture area to the interseismic locked zone is particularly important for earthquake hazard estimation on subduction margins such as cascadia where there have been no great historical events

commensal worm traces and possible juvenile thalassinidean burrows associated with ophiomorpha nodosa pleistocene southern brazil abstract the pleistocene chui formation at osorio rio grande do sul brazil consists of coastal marine and eolian sands the former containing abundant and well preserved ophiomorpha nodosa burrow systems detailed ichnological study has revealed interesting features associated with them small sized ophiomorpha here assigned to a new ichnospecies o puerilis are interpreted as possible burrows of juvenile thalassinidean crustaceans probably belonging to the same species as the producers of larger o nodosa additionally helicoidal burrows with thick concentrically laminated linings are associated with the walls of o nodosa they are assigned to the new ichnospecies cylindrichnus helix and they are interpreted as dwellings of commensal annelid worms the association of these three ichnospecies constitutes a fossil example of the role of thalassinideans as ecosystem engineers able to modify their environment and to create new space and resources usable by other organisms

post seismic motion following the 1997 manyi tibet earthquake insar observations and modelling summary on november 8 1997 a mw 7 6 earthquake occurred in the manyi region of northern tibet near the western end of the kunlun fault over 7 m of left lateral slip occurred on a 200 kmlong fault here we use insar observations of post seismic surface deformation following the manyi earthquake to investigate possible causal mechanisms time series of deformation are constructed from 26 interferograms covering the entire length of the fault for nearly 4 yr after the earthquake three different modelling approaches are used to try and understand the observed variations in surface displacement first order poroelastic models predict displacement fields which do not match those observed modelling of viscoelastic stress relaxation in a half space with standard linear solid rheology beneath an elastic lid provides a reasonable fit to the observations and demonstrates that two relaxation times are needed to characterize the post seismic transient the best fitting viscosity is 4 10 18 pa s and the fully relaxed shear modulus is 32 per cent of the purely elastic value a model with a maxwell viscoelastic halfspace underlying the lid cannot explain the observations at later times larger viscosities are required than at earlier times this increase in effective viscosity with time may be consistent with stress relaxation occurring in a power law rheology the time series are also inverted for distributed afterslip on an extension of the coseismic rupture along strike correlation of coseismic and post seismic slip maxima suggests that afterslip is a plausible mechanism the maximum slip in the afterslip model is 0 72 m after 3 yr and the equivalent moment release is approximately 20 per cent of the coseismic moment this study shows that it is possible to rule out certain mechanisms as the dominant post seismic process but with the current insar data set it is difficult to distinguish between other plausible options

displacement fields due to the 1946 nankaido earthquake in a laterally inhomogeneous structure with the subducting philippine sea plate a three dimensional finite element approach abstract the displacement fields associated with the 1946 nankaido earthquake have been investigated in detail taking into account the configuration of the philippine sea plate subducting beneath southwest japan we used a three dimensional finite element method for the elastic problem to examine the effects of three dimensionally inhomogeneous structure some differences in the displacement patterns between homogeneous and inhomogeneous media have been identified the amounts of displacements are large in low rigidity portions such as in the crust and mantle wedge and are small in a high rigidity portion composed of the subducting plate the inhomogeneity affects horizontal displacements at the earth s surface more than vertical displacements if the rigidity and the poisson ratio given here to southwest japan are appropriate the fault parameters of the earthquake which have been estimated from simple dislocation models in a homogeneous semi infinite medium need to be modified somewhat the present computations indicate that larger dip angles and smaller fault slips are more appropriate fault parameters when structural inhomogeneity is taken into account this suggests that the discrepancy in the obtained total seismic moment between the geodetic and seismic models of the nankaido earthquake could be reduced

deformation and stress change associated with plate interaction at subduction zones a kinematic modelling summary the interseismic deformation associated with plate coupling at a subduction zone is commonly simulated by the steady slip model in which a reverse dip slip is imposed on the down dip extension of the locked plate interface or by the backslip model in which a normal slip is imposed on the locked plate interface it is found that these two models although totally dierent in principle produce similar patterns for the vertical deformation at a subduction zone this suggests that it is almost impossible to distinguish between these two models by analysing only the interseismic vertical deformation observed at a subduction zone the steady slip model cannot correctly predict the horizontal deformation associated with plate coupling at a subduction zone a fact that is proved by both the numerical modelling in this study and the gps global positioning system observations near the nankai trough southwest japan it is therefore inadequate to simulate the eect of the plate coupling at a subduction zone by the steady slip model it is also revealed that the unphysical assumption inherent in the backslip model of imposing a normal slip on the locked plate interface makes it impossible to predict correctly the horizontal motion of the subducted plate and the stress change within the overthrust zone associated with the plate coupling during interseismic stages if the analysis made in this work is proved to be correct some of the previous studies on interpreting the interseismic deformation observed at several subduction zones based on these two models might need substantial revision on the basis of the investigations on plate interaction at subduction zones made using the finite element method and the kinematic mechanical conditions of the plate coupling implied by the present plate tectonics a synthesized model is proposed to simulate the kinematic eect of the plate interaction during interseismic stages a numerical analysis shows that the proposed model designed to simulate the motion of a subducted slab can correctly produce the deformation and the main pattern of stress concentration associated with plate coupling at a subduction zone the validity of the synthesized model is examined and partially verified by analysing the horizontal deformation observed by gps near the nankai trough southwest japan

the anatomy of the 2009 l aquila normal fault system central italy imaged by high resolution foreshock and aftershock locations 1 on 6 april 01 32 utc 2009 a mw 6 1 normal faulting earthquake struck the axial area of the abruzzo region in central italy we study the geometry of fault segments using high resolution foreshock and aftershock locations two main sw dipping segments the l aquila and campotosto faults forming an en echelon system 40 km long nw trending the 16 km long l aquila fault shows a planar geometry with constant dip 48 through the entire upper crust down to 10 km depth the campotosto fault activated by three events with 5 0 mw 5 2 shows a striking listric geometry composed by planar segments with different dips along depth rather than a smoothly curving single fault surface the investigation of the spatiotemporal evolution of foreshock activity within the crustal volume where the subsequent l aquila main shock nucleated allows us to image the progressive activation of the main fault plane from the beginning of 2009 the foreshocks activated the deepest portion of the fault until a week before the main shock when the largest foreshock mw 4 0 triggered a minor antithetic segment seismicity jumped back to the main plane a few hours before the main shock secondary synthetic and antithetic fault segments are present both on the hanging and footwall of the system the stress tensor obtained by inverting focal mechanisms of the largest events reveals a ne trending extension and the majority of the aftershocks are kinematically consistent deviations from the dominant extensional strain pattern are observed for those earthquakes activating minor structures

the sedimentological significance of concentrically laminated burrows from lower cretaceous ca bentonites oxfordshire concentrically laminated burrows are common at outcrop and in core in mesozoic and younger shallow marine siliciclastic sedimentary rocks they are generally referred to cylindrichnus concentricus howard an imperfectly understood ichnotaxon here considered to be a nomen dubium concentric lamination can be formed in several ways either actively contrived by the producer or by passive filling draught filling of a burrow with constricted apertures in the latter case the fill cannot be regarded as an ichnotaxobase passive infilling of concentrically laminated bow form deep tier burrows is described from lower cretaceous aptian sedimentary rocks associated with fuller9s earth ca bentonite at baulking oxfordshire the distribution and taphonomy provide information on the sedimentological setting of the tephra and associated sediments the lower seam was already compacted and of clay grade before it was repeatedly eroded and colonized the latter has significantly reduced seam quality subsequent sedimentation was essentially aggradational including the uniquely preserved upper bentonite which had a complex recovery history among other ichnotaxa concentrically laminated thalassinoides and possibly diplocraterion may be misidentified as cylindrichnus since thalassinoides and diplocraterion are important indicators of bounding surfaces information of significance in sequence stratigraphy may be lost as a consequence citations of cylindrichnus in the literature are briefly discussed many must be assigned to other ichnotaxa

coseismic ground deformation of the 6 april 2009 l aquila earthquake central italy mw6 3 1 we provide field data of coseismic ground deformation related to the 6 april mw 6 3 l aquila normal faulting earthquake three narrow fracture zones were mapped paganica colle enzano p e mt castellano mt stabiata c s and san gregorio sg these zones define 13 km of surface ruptures that strike at 130 140 we mapped four main types of ground deformation free faces on bedrock fault scarps faulting along synthetic splays and fissures with or without slip that are probably due to the near surface lithology of the fault walls and the amount of slip that approached the surface coseismically the p e and c s zones are characterized by downthrow to the sw up to 10 cm and opening up to 12 cm while the sg zone is characterized only by opening afterslip throw rates of 0 5 0 6 mm day were measured along the paganica fault where paleoseismic evidence reveals recurring paleo earthquakes and post 24 8 kyr slip rate 0 24 mm yr

distribution and magnitude of post seismic deformation of the 2009 l aquila earthquake m6 3 surface rupture measured using repeat terrestrial laser scanning we captured post seismic deformation close to the surface rupture of the 2009 l aquila earthquake m6 3 central italy using repeat terrestrial laser scan tls methods from 8 to 126 d after the earthquake we repeatedly laser scanned four road surfaces that intersected the earthquake surface rupture we modelled vertical near field deformation at millimetre level precision by comparing subsequent laser scan data sets to the first acquired at each site the horizontal post seismic deformation at each site was measured between reflectors paired across the rupture the tls data were supplemented by total station data from a fifth site which measured the vertical and horizontal components of post seismic deformation between two points spanning the rupture we find post seismic deformation increased between 44 and 126 d at the southeastern end of the rupture beneath which a significant gradient in coseismic slip exists within the fault zone the location rate of decay and spatially localized nature of the post seismic deformation within tens of metres of the surface rupture suggests it is due to afterslip in the fault zone driven by increased shear stresses at the edges of regions which slipped coseismically we note that the magnitude of post seismic deformation in the far field obtained from insar and gps is not significantly greater than the deformations we have measured close to the rupture we suggest that shallow localized afterslip within the fault zone is responsible for the majority of the regional post seismic deformation field

precambrian cambrian boundary global stratotype ratified and a new perspective of cambrian time the precambrian cambrian boundary global stratotype is the base of the phycodes pedum zone at fortune head southeastern newfoundland the initial two stage radiation of the phanerozoic fauna the appearance of phanerozoic aspect trace producers and subsequent origin of diverse skeletalized metazoans was earliest cambrian fossil assemblages with deep complex burrows or originally mineralized skeletal fossils with exception of cloudina are early cambrian or younger correlation into avalon indicates that strata once referred to the proterozoic e g manykaian or nemakit daldynian and rovno stages are lowest cambrian and that the siberian tommotian stage is middle lower cambrian the thick sequence and complex epeirogenic history of the placentian series as compared with the trilobite bearing branchian series suggest that most early cambrian time is represented by the subtrilobitic lower cambrian

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

a quantitative interpretation on possible correlations between intraplate seismic activity and interplate great earthquakes along the nankai trough abstract the tonankai earthquake occurred in 1944 along the nankai trough between the continental eurasian plate and the subducting philippine sea plate we investigated spatial and temporal correlations between the occurrence of this event and intraplate seismic activities in the inland region of southwest japan in order to elucidate the possible relationship and dynamic coupling between the 1944 tonankai and the 1946 nankaido earthquakes we calculated stress changes due to the tonankai earthquake by applying a three dimensional finite element method and compared them with post seismic activity agreement between them appears quite well at a depth of 10 km indicating that stress release in an e w direction associated with the tonankai earthquake may have reduced the seismic activity in the inland region particularly the observed drastic decrease of seismicity in the wakayama region just after this event can be explained by significant decrease of compressive stresses in the e w direction extensive seismicity quiescence preceding the 1946 nankaido earthquake which occurred adjacent to the source region of the tonankai event may be related to the enhancement of n s oriented compressive stress due to accelerating northward movement of the philippine sea plate therefore in addition to the decrease of stresses in the e w direction the increase of the n s oriented compressive stresses might play an important role to yield low seismic activity just after the tonankai event the calculated results show that the post seismic shear stress increased and the normal stress decreased near the hypocentral area of the 1946 nankaido earthquakes while the shear stress decreased and normal stress increased in its surrounding area on the fault this indicates that the tonankai earthquake made it easier for the rupture of the nankaido earthquake to originate at the observed hypocenter this triggering mechanism may explain the synchronous pattern of historical great interplate earthquakes along the nankai trough a great earthquake occurs in the western region within a few years after the first breakage in the eastern block

review of earth science research using terrestrial laser scanning abstract the application of advanced remote sensing technologies including terrestrial laser scanning tls to the earth sciences has increased rapidly in the last two decades improving the spatial and temporal resolution of data terrestrial laser scanning units have evolved into a common tool in studies of spectral and structural geology seismology natural hazards geomorphology and glaciology special consideration of the advantages and limitations of tls in each of these fields is discussed in depth in the context of important work published in each field the workflow used in a tls survey is crucial to the success of the survey and field specific earth science workflows are therefore also discussed products based on tls data such as triangulated irregular networks tin and digital surface models dsm are commonplace tools throughout the earth sciences and the use of these tools to measure slip distributions fault geometries aeolian transport river bed morphologies and flows and other research problems is expanded on where appropriate the review concludes with a discussion of recent trends in tls instrument development and their potential impact on the use of tls in the earth sciences in the future

implications of structural segmentation during earthquakes the 1995 egion earthquake gulf of corinth greece the egion earthquake which occurred in the gulf of corinth central greece ms 6 2 on 15 june 1995 was caused by normal slip on the north dipping and wnw trending egion fault the egion fault ruptured at depth during the egion mainshock and probably re ruptured at shallow level during the largest aftershock the surface trace of the egion fault has a segmented geometry linkage between three segments which show long term deformation differences as well as coseismic segmentation enabled all segments to be incorporated in an earthquake segment the surface ruptures continued to grow after the coseismic motion the afterslip throw of the fault 10 weeks after the main event was equal to the 3 cm value for maximum coseismic slip this afterslip was accompanied by uplift of the footwall block and a warp like hangingwall subsidence folding this pattern of deformation was associated with more complex deformation at the western end of the earthquake segment here afterslip was accompanied by general subsidence of the whole area between 25th june and 30th july followed by uplift of the whole area without afterslip between 30th july and 2nd september the afterslip rate averaged over the 73 day period after the main event varied from 0 48 mm day 1 along the central part of the earthquake segment to 0 16 mm day 1 at the eastern end of the earthquake segment

probabilistic estimates of surface coseismic slip and afterslip for hayward fault earthquakes we examine the partition of long term geologic slip on the hayward fault into interseismic creep coseismic slip and afterslip using monte carlo simulations we compute expected coseismic slip and afterslip at three alinement array sites for hayward fault earthquakes with nominal moment magnitudes ranging from about 6 5 to 7 1 we consider how interseismic creep might affect the coseismic slip distribution as well as the variability in locations of large and small slip patches and the magnitude of an earthquake for a given rupture area we calibrate the estimates to be consistent with the ratio of interseismic creep rate at the alinement array sites to the geologic slip rate for the hayward fault we find that the coseismic slip at the surface is expected to comprise only a small fraction of the long term geologic slip the median values of coseismic slip are less than 0 2 m in nearly all cases as a result of the influence of interseismic creep and afterslip however afterslip makes a substantial contribution to the long term geologic slip and may be responsible for up to 0 5 1 5 m median plus one standard deviation s d of additional slip following an earthquake rupture thus utility and transportation infrastructure could be severely impacted by afterslip in the hours and days following a large earthquake on the hayward fault that generated little coseismic slip inherent spatial variability in earthquake slip combined with the uncertainty in how interseismic creep affects coseismic slip results in large uncertainties in these slip estimates

space time distribution of afterslip following the 2009 l aquila earthquake 1 the inversion of multitemporal dinsar and gps measurements unravels the coseismic and postseismic afterslip slip distributions associated with the 2009 mw 6 3 l aquila earthquake and provides insights into the rheological properties and long term behavior of the responsible structure the paganica fault well resolved patches of high postseismic slip 10 20 cm appear to surround the main coseismic patch maximum slip 1 m through the entire seismogenic layer above the hypocenter without any obvious depth dependent control time series of postseismic displacement are well reproduced by an exponential function with best fit decay constants in the range of 20 40 days a sudden discontinuity in the evolution of released postseismic moment at 130 days after the main shock does not correlate with independent seismological and geodetic data and is attributed to residual noise in the insar time series the data are unable to resolve migration of afterslip along the fault probably because of the time interval six days between the main shock and the first radar acquisition surface fractures observed along the paganica fault follow the steepest gradients of postseismic line of sight satellite displacements and are consistent with a sudden and delayed failure of the shallow layer in response to upward tapering of slip the occurrence of afterslip at various levels through the entire seismogenic layer argues against exclusive depth dependent variations of frictional properties on the fault supporting the hypothesis of significant horizontal frictional heterogeneities and or geometrical complexities we support the hypothesis that such heterogeneities and complexities may be at the origin of the long term variable behavior suggested by the paleoseismological studies rupture of fault patches with dimensions similar to that activated in 2009 appears to have a 500 year recurrence time interval documented by paleoseismic and historical studies in addition to that paleoseismological evidence of large 0 5 m coseismic offsets seems to require seismic events recurring every 1000 2000 years characterized by 1 multisegment linkage 2 surface ruptures larger than in 2009 and 3 complete failure of the 2009 coseismic and postseismic patches

the nisi fault as a key structure for understanding the active deformation of the nw peloponnese greece abstract the previously unknown nisi fault in nw peloponnese was ruptured during the 2008 movri mountain earthquake attaining a maximum offset of 25 cm the fault is interpreted as a branch of a flower structure above a blind strike slip fault we investigate the nisi fault seismotectonic evolution using morphotectonic analysis in order to determine whether the landscape is affected by tectonic forcing and paleoseismology to determine earthquake recurrence interval and fault slip rates we applied several geomorphic indices such as the asymmetry factor af the stream length gradient index sl the valley floor width to valley height ratio vf the mountain front sinuosity smf the drainage basin shape bs and the hypsometric curve hc in four large drainage basins of the study area the results show that fault related vertical motions and the associated tilting influenced the drainage geometry and the landscape development values of stream gradient indices sl are relatively high close to the fault trace mountain front sinuosity smf mean values along the fault zones range from 1 12 to 1 23 valley floor width to valley height ratios vf mean values along the studied fault range between 0 21 and 2 50 drainage basin shape bs mean values along the fault range from 1 04 to 3 72 lateral fault growth was likely achieved by propagation primarily towards north northwestward the paleoseismic history of the fault investigated by a trench and 14c dating of seven samples indicates two morphogenic earthquakes in the last 1 kyr therefore we suggest that the nisi fault displays a slip rate on the order of 1 mm yr and a recurrence interval ranging between 300 and 600 years from a seismotectonic point of view the fault is classified as high activity rate with abundant but discontinuous geomorphic evidence of its activity other similar faults affecting the western peloponnese can be envisaged with a similar procedure additionally the seismic history and surface expression of the nisi fault resembles other faults of similar length in greece and italy particularly a crucial issue in terms of seismic risk management is that neotectonic analysis has to be envisaged carefully on short in length faults since these faults can be possibly related to strong earthquakes

an andean model of interplate coupling and strain partitioning applied to the flat subduction zone of sw japan nankai trough abstract transcurrent motion is commonly observed in cases of oblique subduction yet the causes remain controversial a model of increased interplate coupling linked to flat subduction is proposed as a mechanism for producing strain partitioning at a great distance several hundred km from the trench the model originally developed for the north andean margin is applied to the geodynamics of sw japan here along the nankai trough and below adjacent sw honshu flat subduction occurs due to the relatively young age m 7 and nine additional m 6 earthquakes in the past 300 years dextral strike slip focal mechanisms for 15 modern and historical events indicate a significant degree of subduction related strain partitioning manifested by right lateral strike slip faulting along the adakitic volcanic arc some 400 km from the nankai trough

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 2009 central italy earthquake seen through 0 5 myr long tectonic history of the l aquila faults system abstract on 6 april 2009 a mw 6 3 earthquake struck l aquila and dozens of neighbouring villages abruzzo central italy causing 308 deaths and with thousands injured within italian seismicity this was the strongest event since 1980 irpinia mw 6 9 and the first located so close to a large city since 1908 messina mw 7 3 consistent data from an integrated approach including stratigraphy geomorphology tephrochronology and paleoseismology have allowed us to identify a 19 km long hitherto poorly known structure as being responsible for this earthquake paganica san demetrio fault system psdfs the fingerprinting of four well dated tephra layers and a detailed outline of the geomorphological and stratigraphic setting have provided the basis for assessing the behaviour of the psdfs since its early activity here dated at least ca 500 ka to the present the slip rate of the structure calculated over different time windows has fluctuated slightly ca 0 5 mm yr paleoseismological analyses revealed the traces of the last surface faulting events thus we unambiguously recognise the offset associated with the mw 6 7 earthquake of 1703 which was previously related to other conterminous structures along with an older comparable strong event speculatively ascribed to an event purely known as the ad 801 central apennine earthquake this study shows that a long term to short term integrated approach is crucial in seismic hazard evaluation especially when dealing with fault systems that are difficult to trace geomorphically despite being capable of generating 2009 like earthquakes or even stronger events when conterminous structures are also involved

composite ichnofabrics and tiering of burrows infaunal communities in marine environments typically are tiered that is different taxa live at different depths within the sediment tiered suites of biogenic structures yield complex biogenic sedimentary fabrics ichnofabrics with the traces of deep burrowing organisms overprinted on those of shallow burrowing organisms careful analysis of crosscutting relationships of burrows in such composite ichnofabrics allows reconstruction of the tiered nature of fossil endobenthic communities it is important to recognize that the best preserved and most prominently displayed trace fossils in most assemblages usually represent the deepest tier thus they were farther removed from the sea floor and therefore less indicative of actual sea floor conditions than the more poorly preserved traces of the shallower tiers on which the deeper traces are juxtaposed

new paleoseismological data from the gran sasso d italia area central apennines 1 paleoseismological analyses along the campo imperatore normal fault cif in the gran sasso massif which is an area characterized by the absence of significant historical earthquakes highlight the occurrence of surface faulting after the 5th 3rd cent bc and around the 6th 5th millenium bc these ages agree with those reported by giraudi and frezzotti 1995 on the western tip of the cif thus suggesting the possible entire rupture of the 30 km long cif during m7 events these data contribute to the re evaluation of the seismic hazard of a large surrounding area including the city of l aquila 100 000 inhabitants which is located 20 km from the cif in the hangingwall side index terms 7221 seismology paleoseismology 7223 seismology seismic hazard assessment and prediction 7230 seismology seismicity and seismotectonics 8107 tectonophysics continental neotectonics

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

bow shaped concentrically laminated polychaete burrows a cylindrichnus concentricus ichnofabric from the miocene of tarragona ne spain abstract bow shaped concentrically laminated burrows from the miocene of the el camp de tarragona basin in northeastern spain are described although the ichnotaxonomic assignment of these traces is controversial they are here designated as cylindrichnus concentricus a detailed analysis of the overall architecture of the burrows and the constructional features of their characteristic linings allows direct comparison with structures produced today by terebellid polychaetes similar trace fossils have been described in the literature from shallow marine environments as old as the jurassic which highlights the recurrence of this ichnotaxon and its importance in these settings c concentricus occurs in tarragona as an elite trace fossil in intensely bioturbated ichnofabrics formed in offshore settings with low sedimentation rates a comparable depositional setting to that of similar neogene ichnofabrics

the interplate coupling and stress accumulation process of large earthquakes along the nankai trough southwest japan derived from geodetic and seismic data abstract the interplate coupling and stress accumulation process associated with the subduction of the philippine sea plate beneath the eurasian plate along the nankai trough where large earthquakes have occurred periodically have been investigated in detail taking into account the three dimensional complicated structure of the philippine sea plate and its motion relative to the eurasian plate for this purpose we mainly used extensive geodetic data in southwest japan such as levelling tide gauge and trilateration which presumably are effective means of revealing coupling properties and applied a three dimensional finite element method here two seismic periods associated with the 1944 tonankai and 1946 nankaido earthquakes were considered interseismic and pre seismic stages comparing the coupled regions obtained for the two cases a possible explanation of its temporal change was proposed it might gradually spread from a shallower to deeper portion with transition from the interseismic to pre seismic stage a comparison of the coupling properties between southwest japan and northeast japan reveals the following properties in southwest japan the coupling is generally strong and its region is limited in a relatively shallow portion the pre seismic coupled regions coincide with the co seismic and post seismic fault zone suggesting that the accumulated stress is released at the time of a large earthquake in northeast japan on the other hand the coupling is weak and its extent appears to reach a depth of about 100 km and the co seismic and post seismic regions are limited to the upper half of the coupled region the weakly coupled region in southwest japan seems to correspond well to the region with high seismic activity a high dip angle subducting slab and the possible existence of seamounts in contrast to the strongly coupled region correlated with low seismicity low dip angle subduction and no seamounts on the western coupled region off shikoku an anomalously strongly coupled region corresponding to a convergence rate of 7 8 cm year 1 was identified this may be caused by geomorphological properties such as the low dip angle of the subducting plate and smooth plate boundary resulting in a large amount of stress concentration there the stress field associated with the interplate coupling was also calculated there is fair agreement between the observations and calculations near the plate boundary beneath the southern kii peninsula and shikoku although the effects of the interplate coupling may have some influence on strike slip faulting with the n s compressive axes beneath shikoku other earthquake generating stress such as a two layered double buckling would be dominant there

fault slip distribution of the 1999 mw 7 1 hector mine earthquake california estimated from postearthquake airborne lidar data the 16 october 1999 hector mine earthquake m w 7 1 was the first large earthquake for which postearthquake airborne light detection and ranging lidar data were collected to image the fault surface rupture in this work we present measurements of both vertical and horizontal slip along the entire surface rupture of this earthquake based on airborne lidar data acquired in april 2000 we examine the details of the along fault slip distribution of this earthquake based on 255 horizontal and 85 vertical displacements using a 0 5 m digital elevation model derived from the lidar imagery the slip measurements based on the lidar dataset are highest in the epicentral region and taper in both directions consistent with earlier findings by other works the maximum dextral displacement measured from lidar imagery is 6 60 1 10 m located about 700 m south of the highest field measurement 5 25 0 85 m our results also illustrate the difficulty in resolving displacements smaller than 1 m using lidar imagery alone we analyze slip variation to see if it is affected by rock type and whether variations are statistically significant this study demonstrates that a postearthquake airborne lidar survey can produce an along fault horizontal and vertical offset distribution plot of a quality comparable to a reconnaissance field survey although lidar data can provide a higher sampling density and enable rapid data analysis for documenting slip distributions we find that relative to field methods it has a limited ability to resolve slip that is distributed over several fault strands across a zone we recommend a combined approach that merges field observation with lidar analysis so that the best attributes of both quantitative topographic and geological insight are utilized in concert to make best estimates of offsets and their uncertainties

twenty years of paleoseismology in italy abstract italy has one of the most complete and historically extensive seismic catalogues in the world due to a unique and uninterrupted flow of written sources that have narrated its seismic history since about the end of the iron age seismic hazard studies have therefore always been mainly based upon this huge mass of data nevertheless the italian catalogue probably lacks many m 6 5 events the seismogenetic structures responsible for which are characterized by recurrence times that are longer than the time span covered by our historical sources for these reasons and as in other countries earthquake data that in italy have been derived from paleoseismological studies should finally become a necessary ingredient in seismic risk assessment indeed over the past 20 years some hundred trenches have been excavated supplying reliable and conclusive data on the recent activities of many faults through to many robust datings of surface fault events these studies have provided the ages of several unknown or poorly known m 6 5 earthquakes here we summarize the state of the art of paleoseismology in italy and present a first catalogue of 56 paleoearthquakes pci that occurred mainly in the past 6 kyr the pci integrates the historical instrumental seismic catalogue and extends it beyond the recurrence time of the seismogenetic faults 2000 1000 yr we feel confident that the use of the pci will enhance future probabilistic seismic hazard assessment and thus contribute to more reliable seismic risk mitigation programs

assessment of sediment sources throughout the proglacial area of a small arctic catchment based on high resolution digital elevation models abstract the article presents calculations of quantitative modifications of the morphology of selected subsystems of a glacial valley through i identification of the spatial distribution of important sources of sediment ii assessment of the spatiotemporal variety of sediment volume and landform morphology and iii assessment of the role of particular subsystems in sediment distribution the study involved a comparison of the results of field measurements from 2010 to 2013 performed in the scott glacier catchment 10 1 km2 in nw wedel jarlsberg land spitsbergen the assessment of the landform surface changes was performed by means of a precise terrestrial laser scanning tls survey the applied field and post processing techniques for oblique laser scanning permitted the acquisition of digital elevation data at a resolution 0 01 m and density 500 pt m 2 this allowed the development of a detailed terrain model and balancing spatial quantitative changes in six research test areas 10 000 m2 located within two subsystems of the catchment in a cascade arrangement in the alluvial valley floor subsystem the survey covered 1 the glacier terminus 2 the intramarginal outwash plain 3 the extramarginal braid plain and 4 the alluvial fan and in the slope subsystem 5 the erosional depositional slope in the gorge through terminal moraines and 6 the solifluction slope three zones differing in terms of the spatiotemporal dynamics of geomorphic processes were distinguished within the two analysed valley subsystems in the valley floor subsystem these are i the zone of basic supply distribution throughout the melting season and ii the redeposition zone distribution particularly during floods and in the slope subsystem iii zone of periodical supply distributed mainly in periods of increased precipitation and rapid increases in temperature in summer and during snow avalanches in winter the glacier and the landforms of the channel and valley floor as well as slope sediments transported as a result of mass wasting processes and activity of the active permafrost layer constitute important sources of sediment supply over a short 3 year timescale evidence of major changes of the surface morphology slopes floodplain and channel platform resulted in varied sediment budgets the subtraction of consecutive dems of the test areas located in the alluvial valley subsystem revealed downstream spatial and volumetric differentiation from the predominance of erosion 79 of volume 43 of area to the dominance of deposition 90 91 respectively in upper part of the valley floor to erosion predominance in the central 88 95 and lower 87 82 part of valley floor the test areas located on the slope subsystem showed the opposite relationship deposition dominance 88 of volume 80 of area in the upper gorge and erosion dominance 99 99 respectively in the lower part solifluction slopes the analysis of short time repeated surveys 3 week survey where volumes were calculated following dem subtraction showed increased deposition 82 of volume 79 of area for the alluvial fan and for solifluction slopes 70 57 respectively

coseismic and initial post seismic slip of the 2009 mw 6 3 l aquila earthquake italy from gps measurements summary here we report the preliminary results of gps data inversions for coseismic and initial afterslip distributions of the mw 6 3 2009 april 6 l aquila earthquake coseismic displacements of continuous and survey style gps sites show that the earthquake ruptured a planar sw dipping normal fault with 0 6 m average slip and an estimated moment of 3 9 1018 nm geodetic data agree with the seismological and geological information pointing out the paganica fault as the causative structure of the main shock the position of the hypocentre relative to the coseismic slip distribution supports the seismological evidence of southeastward rupture directivity these results also point out that the main coseismic asperity probably ended downdip of the paganica village at a depth of few kilometres in agreement with the small 1 10 cm observed surface breaks time dependent post seismic displacements have been modelled with an exponential function the average value of the estimated characteristic times for near field sites in the hanging wall of the fault is 23 9 5 4 d the comparison between coseismic slip and post seismic displacements for the first 60 d after the main shock shows that afterslip occurred at the edges of the main coseismic asperity with a maximum estimated slip of 25 cm and an equivalent seismic moment of 6 5 1017 nm the activation of the paganica fault spatially intermediate between the previously recognized main active fault systems suggests that strain accumulation in the central apennines may be simultaneously active on distinct parallel fault systems

insight into the 2004 sumatra andaman earthquake from gps measurements in southeast asia data collected at 60 global positioning system gps sites in southeast asia show the crustal deformation caused by the 26 december 2004 sumatra andaman earthquake at an unprecedented large scale small but significant co seismic jumps are clearly detected more than 3 000 km from the earthquake epicentre the nearest sites still more than 400 km away show displacements of 10 cm or more here we show that the rupture plane for this earthquake must have been at least 1 000 km long and that non homogeneous slip is required to fit the large displacement gradients revealed by the gps measurements our kinematic analysis of the gps recordings indicates that the centroid of released deformation is located at least 200 km north of the seismological epicentre it also provides evidence that the rupture propagated northward sufficiently fast for stations in northern thailand to have reached their final positions less than 10 min after the earthquake hence ruling out the hypothesis of a silent slow aseismic rupture data culled from gps stations in indonesia malaysia singapore thailand india and china have answered more questions relating to the 26 december sumatra andaman megathrust earthquake permanent displacements were seen 3 000 km away final displacements occurred within 10 minutes of the earthquake ruling out slow aseismic slip on the fault

fluid flow within the damage zone of the boccheggiano extensional fault larderello travale geothermal field central italy structures alteration and implications for hydrothermal mineralization in extensional settings the neogene extensional province of southern tuscany in central italy provides an outstanding example of fossil and active structurally controlled fluid flow and epithermal ore mineralization associated with post orogenic silicic magmatism characterization of the hydrodynamic regime leading to the genesis of the polysulphide deposit known as filone di boccheggiano hosted within the damage zone of the boccheggiano fault is a key target to assess modes of fossil hydrothermal fluid circulation in the region and more generally to provide inferences on fault controlled hydrothermal fluid flow in extensional settings we provide a detailed description of the fault zone architecture and alteration mineralization associated with the boccheggiano ore deposit and report the results of fluid inclusion and stable oxygen isotope studies this investigation shows that the boccheggiano ore consists of an adularia illite type epithermal deposit and that sulphide ore deposition was controlled by channelling of hydrothermal fluids of dominantly meteoric origin within the highly anisotropic permeability structure of the boccheggiano fault the low permeability structure of the fault core compartmentalized the fluid outflow preventing substantial cross fault flow with focused fluid flow occurring at the hangingwall of the fault controlled by fracture permeability fluid inclusion characteristics indicate that ore minerals were deposited between 280 and 350 c in the upper levels of the brittle extending crust lithostatic pressure in the order of 0 1 gpa abundant vapour rich inclusions in ore stage quartz are consistent with fluid immiscibility and boiling and quartz ore vein textures suggest that mineralization in the boccheggiano ore deposit occurred during cyclic fluid flow in a deformation regime regulated by transient and fluctuating fluid pressure conditions results from this study i predict a strongly anisotropic permeability structure of the fault damage zone during crustal extension and ii indicate the rate of secondary structural permeability creation and maintenance by active deformation in the hangingwall of extensional faults as the major factor leading to effective hydraulic transmissivity in extensional terranes these features intimately link ore grade mineralization in extensional settings to telescoping of hydrothermal flow along the hangingwall block s of major extensional fault zones

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

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

surface faulting of the 6 april 2009 mw 6 3 l aquila earthquake in central italy this paper documents evidence of surface faulting associated with the 6 april 2009 moderate sized earthquake ml 5 8 mw 6 3 in the central apennines of italy which caused major damage to the town of l aquila and its surroundings coseismic surface ruptures were mapped for a minimum distance of 2 6 km along the paganica fault a fault still poorly investigated relative to the other active faults nearby which bound much wider range fronts surface rupture length srl and maximum displacement parameters 2 6 km minimum and 10 15 cm respectively are in agreement with what is expected for an mw 6 3 event in the italian apennines tectonic environment different viewpoints exist on the amount of srl and the number of activated faults we propose a pattern of sympathetic and secondary slip on an array of faults around the master seismogenic structure past seismicity and evidence for larger holocene offsets on this and other capable faults nearby prove that the 2009 event is not a good reference event for assessing the seismic hazard of the region nevertheless the 2009 l aquila earthquake once more confirmed the importance of detailed geological studies for a proper seismic hazard assessment and it clearly illustrates the need to pay attention to moderate events and supposedly minor active faults indeed this type of earthquake is rather frequent in the whole mediterranean region and is potentially much more destructive than in the past due to the expanding urban centers and infrastructures inside their epicentral regions and even right above the traces of capable faults

slip along the superstition hills fault associated with the 24 november 1987 superstition hills california earthquake surficial slip along the entire mapped length of the superstition hills fault in southern california occurred in association with the superstition hills earthquake m s 6 6 of 24 november 1987 we made repeated measurements of surface slip at 36 sites along the fault and occupied 64 sites at least once at our sites dextral slip was as high as 48 5 cm 1 day after the earthquake and 71 cm 2 months after the measurements show that slip during the period from hr to several hundred hr following the event is described by a simple power law of time extrapolation to t 1 min indicates that co seismic slippage ranged from 5 to 23 cm at 10 of our best recorded sites suggesting that finite co seismic slippage occurred along the length of the fault these extrapolations are supported by a measurement made at imler road 30 min after the shock measurements are complete through october 1988 at many sites the form of slip rate was decay changed from power law to a function of log time during the interval between 300 and 500 hr after the earthquake logarithmic slip rate decay in time was observed for a period of several yr after the parkfield borrego mountain and imperial valley earthquakes those measurements may have begun too late to resolve power law behavior at early times if current logarithmic behavior of the superstition hills fault persists right lateral slippage will approach 90 cm 10 yr after the rupture changes in the along fault displacement profile correlate well with geometric features including a fault bend and a major fault step moreover slip behavior appears to be correlated to the thickness of sedimentary cover along the fault also the northern half of the fault is bounded by a large block of continental crystalline basement the presence of this block may have contributed to the relatively uniform early slip behavior observed there

geomorphology of active faulting and seismic hazard assessment new tools and future challenges by witold zuchiewicz and jerzy zasadni 2012 intended for this volume young tectonics of the outer western carpathians in the light of some morphometric indices in this paper we test the applicability of some morphometric indices commonly used in tectonic geomorphological studies to the area of the outer western carpathians representing an alpine fold and thrust belt this belt was shaped largely in miocene times and shows traces of pliocene quaternary tectonic activity consisting mainly in some remnant folding and faulting this is indicated by scarce examples of faulting within quaternary strata numerous cases of clast fracturing owing to palaeoearthquakes of relatively large magnitudes as well as warping and tilting of pleistocene and holocene strath terraces analysis of selected morphometric indices valley floor width valley height ratio riverbed gradients stream length gradient index basin elongation ratios and others conducted for the entire region and some chosen test areas in the westernmost part of the outer western ac c ep te d m an u sc r ip t accepted manuscript 24 carpathians proved their usefulness in detecting zones showing tendencies to young surface uplift however in the case of the stream length gradient index sl hack s index a word of caution should be added since the index is extremely sensitive to lithologic contrasts in the bedrock and its applicability to young tectonic analysis of fold and thrust belts appears to be strongly limited dr andrzej piotrowski apiot pgi gov pl szczecinie panstwowy instytut geologiczny szczecin poland and dr klaus reicherter rwth aachen university germany

surface faulting along the superstition hills fault zone and nearby faults associated with the earthquakes of 24 november 1987 the m 6 2 elmore desert ranch earthquake of 24 november 1987 was associated spatially and probably temporally with left lateral surface rupture on many northeast trending faults in and near the superstition hills in western imperial valley three curving discontinuous principal zones of rupture among these breaks extended northeastward from near the superstition hills fault zone as far as 9 km the maximum observed surface slip 12 5 cm was on the northern of the three the elmore ranch fault at a point near the epicenter twelve hours after the elmore ranch earthquake the m 6 6 superstition hills earthquake occurred near the northwest end of the right lateral superstition hills fault zone surface rupture associated with the second event occurred along three strands of the zone here named north and south strands of the superstition hills fault and the wienert fault for 27 km southeastward from the epicenter in contrast to the left lateral faulting which remained unchanged throughout the period of investigation the right lateral movement on the superstition hills fault zone continued to increase with time a behavior that was similar to other recent historical surface ruptures on northwest trending faults in the imperial valley region we measured displacements over 339 days at as many as 296 sites along the superstition hills fault zone and repeated measurements at 49 sites provided sufficient data to fit with a simple power law data for each of the 49 sites were used to compute longitudinal displacement profiles for 1 day and to estimate the final displacement that measured slips will approach asymptotically several years after the earthquakes the maximum right lateral slip at 1 day was about 50 cm near the south central part of the north strand of superstition hills fault and the predicted maximum final displacement is probably about 112 cm at imler road near the center of the south strand of the superstition hills fault the overall distributions of right lateral displacement at 1 day and the estimated final slip are nearly symmetrical about the midpoint of the surface rupture the average estimated final right lateral slip for the superstition hills fault zone is about 54 cm the average left lateral slip for the conjugate faults trending northeastward is about 23 cm the southernmost ruptured member of the superstition hills fault zone newly named the wienert fault extends the known length of the zone by about 4 km the southern half of this fault south of new river expressed only vertical displacement on a sinuous trace the maximum vertical slip by the end of the observation period there was about 25 cm but its growth had not ceased photolineaments southeast of the end of new surface rupture suggest continuation of the superstition hills fault zone in farmland toward mexico

characteristic trace fossils in nearshore to offshore sequences upper cretaceous of east central utah more than 20 trace fossil species occur in marine facies of the cretaceous star point and blackhawk formations in the book cliffs and wasatch plateau provinces of utah major genera include ancorichnus arenicolites aulichnites chondrites conichnus cylindrichnus medousichnus ophiomorpha palaeophycus planolites rosselia schaubcylindrichnus scolicia skolithos teichichnus teredolites and thalassinoides newly named taxa include ancorichnus capronus medousichnus loculatus and rosselia chonoides most trace fossils occur in characteristic albeit intergradational ichnofacies correlative with major lithofacies of regressive nearshore to offshore sequences the latter include foreshore foreshore shoreface transition shoreface and offshore facies landward facies are typified by clean well sorted well stratified sparsely burrowed sandstones seaward facies except where interrupted by hummocky bedded sandstones exhibit successively less pure less well sorted and stratified more intensely

the 2009 l aquila earthquake central italy a source mechanism and implications for seismic hazard an edited version of this paper was published by agu copyright 2009 american geophysical union

crowded tubular tidalites in miocene shelf sandstones of southern iberia abstract the passive and active fill of burrows potentially stores information about sedimentary processes that are otherwise not preserved in the rock record in recent years abandoned passively filled vertical burrows were introduced as tubular tidalites when their infilling displays rhythmic lamination reflecting a tidal signature in the shallow marine miocene sandstones exposed at oura southern portugal 36 tubular tidalites occur in a 1 5 m thick interval their high abundance is likely a consequence of both an environment favourable for the production of open burrows in a tidal setting and post depositional conditions facilitating the preservation of the tubular tidalites besides vertical tubes 13 horizontal burrows preserve a tidal signature indicating draught fill processes all specimens belong to thalassinoides and for the first time to gyrolithes the rhythmic infill of two well preserved specimens shows two significant features 1 the thickness pattern allows for differentiation into groups having 7 couplets consisting of a dark and a light lamina or multiples thereof and 2 the thickness patterns of both consecutive couplets as well as dark and light laminae match sine curves both patterns indicate a diurnal tidal cyclicity the tidalites record up to four spring tide and three neap tide cycles in addition to the neap spring cycles a long period lunar fortnightly tide regime can be envisaged the tubular tidalites imply diurnal tides during the miocene in contrast to the recent semidiurnal tides affecting southern portugal

coupling of tectonic loading and earthquake fault slips at subduction zones because of the viscoelastic behaviour of the earth accumulation of elastic strain energy by tectonic loading and release of such energy by earthquake fault slips at subduction zones may take place on different spatial scales if the lithospheric plate is acted upon by distant tectonic forces strain accumulation must occur in a broad region however an earthquake releases strain only in a region comparable to the size of the rupture area a two dimensional finite element model of a subduction zone with viscoelastic rheology has been used to investigate the coupling of tectonic loading and earthquake fault slips a fault lock and unlock technique is employed so that the amount of fault slip in an earthquake is not prescribed but determined by the accumulated stress the amount of earthquake fault slip as a fraction of the total relative plate motion depends on the relative sizes of the earthquake rupture area and the region of tectonic strain accumulation as well as the rheology of the rock material the larger the region of strain accumulation is compared to the earthquake rupture the smaller is the earthquake fault slip the reason for the limited earthquake fault slip is that the elastic shear stress in the asthenosphere induced by the earthquake resists the elastic rebound of the overlying plate since rapid permanent plate shortening is not observed at subduction zones there must be either strain release over a large region or strain accumulation over a small region over earthquake cycles the former can be achieved only by significant aseismic fault slip between large subduction earthquakes the most likely mechanism for the latter is the accumulation of elastic strain around isolated locked asperities of the fault which requires significant aseismic fault slip between asperities

shallow subsurface structure of the 2009 april 6 mw 6 3 l aquila earthquake surface rupture at paganica investigated with ground penetrating radar p the shallow subsurface structure of the 2009 april 6 m w 6 3 l aquila earthquake surface rupture at paganica has been investigated with ground penetrating radar to study how the surface rupture relates spatially to previous surface displacements during the holocene and pleistocene the discontinuous surface rupture stepped between en echelon parallel faults within the overall fault zone that show clear holocene pleistocene offsets in the top 10 m of the subsurface some portions of the fault zone that show clear holocene offsets were not ruptured in 2009 having been bypassed as the rupture stepped across a relay zone onto a fault across strike the slip vectors defined by opening directions across surface cracks indicate dip slip normal movement whose azimuth remained constant between 210 degrees and 228 degrees across the zone where the rupture stepped between faults we interpret maximum vertical offsets of the base of the holocene summed across strike to be 4 5 m which if averaged over 15 kyr gives a maximum throw rate of 0 23 0 30 mm yr 1 consistent with throw rates implied by vertical offsets of a layer whose age we assume to be similar to 33 ka this compares with published values of 0 4 mm yr 1 for a minimum slip rate implied by offsets of middle pleistocene tephras and 0 24 mm yr 1 since 24 8 kyr from palaeoseismology the paganica fault although clearly an important active structure is not slipping fast enough to accommodate all of the 3 5 mm yr 1 of extension across this sector of the apennines other neighbouring range bounding active normal faults also have a role to play in the seismic hazard

paleoseismicity of the ovindoli pezza fault central apennines italy a history including a large previously unrecorded earthquake in the middle ages 860 1300 a d geomorphic and trenching investigations along the ovindoli pezza fault show that this normal fault is one of the major seismogenic faults in the central apennines we found clear geological evidence for three holocene surface faulting earthquakes on this fault the most recent earthquake occurred in the middle ages between 860 and 1300 a d the penultimate occurred about 1900 b c or shortly after and the oldest probably occurred between 3300 and 5000 b c although the most recent surface faulting earthquake occurred during historical time no evidence for it have been found in the historical record slip per event ranges between 2 and 3 m and the length of the rupture is at least 12 20 km suggesting m 6 5 7 0 for the paleoearthquakes the dip slip rate determined from trenching is 0 7 1 2 mm yr and is consistent with the long term slip rate of 0 9 2 5 mm yr lower values preferred obtained from displaced geomorphic features trench data combined with long term slip rate estimates suggest the recurrence interval is longer than a millennium and possibly as long as 3300 years the time elapsed since the most recent earthquake is 700 1130 years the seismic behavior of the ovindoli pezza fault is consistent with other well known seismogenic faults of the central and southern apennines the lack of mention or mislocation of the most recent event on the ovindoli pezza fault in the historical record of the past two millennia should be attributed mainly to the unsettled cultural and social conditions and poor economic state that characterized the middle ages especially in thinly populated regions such as the central apennines this example highlights an intrinsic limit of the historical data and raises the possibility that other regions considered seismically quiet on the basis of a long historical record may in reality have had large earthquakes that were not recorded

radiography of a normal fault system by 64 000 high precision earthquake locations the 2009 l aquila central italy case study 1 we studied the anatomy of the fault system where the 2009 l aquila earthquake mw 6 1 nucleated by means of 64 k high precision earthquake locations spanning 1 year data were analyzed by combining an automatic picking procedure for p and s waves together with cross correlation and double difference location methods reaching a completeness magnitude for the catalogue equal to 0 7 including 425 clusters of similar earthquakes the fault system is composed by two major faults the high angle l aquila fault and the listric campotosto fault both located in the first 10 km of the upper crust we detect an extraordinary degree of detail in the anatomy of the single fault segments resembling the degree of complexity observed by field geologists on fault outcrops we observe multiple antithetic and synthetic fault segments tens of meters long in both the hanging wall and footwall along with bends and cross fault intersections along the main fault and fault splays the width of the l aquila fault zone varies along strike from 0 3 km where the fault exhibits the simplest geometry and experienced peaks in the slip distribution up to 1 5 km at the fault tips with an increase in the geometrical complexity these characteristics similar to damage zone properties of natural faults underline the key role of aftershocks in fault growth and co seismic rupture propagation processes additionally we interpret the persistent nucleation of similar events at the seismicity cutoff depth as the presence of a rheological i e creeping discontinuity explaining how normal faults detach at depth