regional moment tensor inversion for strong aftershocks of the august 17 1999 izmit earthquake mw 7 4 we analyzed the source mechanisms of the thirty largest aftershocks 4 0 ml 6 2 of the august 17 1999 izmit earthquake mw 7 4 by applying the regional moment tensor inversion method using data from near regional broadband stations the inversion solutions were compared to 17 well constrained first motion solutions and were seen to be in good agreement we found that the dominance of strike slip motion is the main characteristic of the izmit earthquake sequence significant aftershock activity was recorded to the west and east of the un ruptured extremities in the east the aftershocks located near the town of duzce represent an early replica of the november 12 1999 duzce earthquake mw 7 2 in terms of locations and source mechanisms in the marmara sea where the fault geometry is still very poorly resolved most aftershocks have right lateral strike slip solutions with strike direction parallel to the submerged branches of the north anatolian fault

stress evolution in southern california and triggering of moderate small and micro size earthquakes we calculate the evolution of stresses in southern california extending the study of deng and sykes 1997 by increasing from 6 to 36 the number of earthquakes for which coseismic changes in stress are computed and by expanding from m 6 to m 1 8 the range of magnitudes m of events whose focal mechanism solutions are examined in the context of the evolving stress field the cumulative stress on a given date is calculated with respect to an arbitrary zero baseline just before the 1812 wrightwood earthquake by taking into account the long term stress loading associated with 98 fault segments and coseismic stress changes for 36 significant earthquakes our calculations indicate that more than 85 of m 5 earthquakes from 1932 1995 occurred in regions of positive change in coulomb failure function cff most of the remaining about 15 earthquakes that occurred in areas of negative cff fall very close to boundaries between positive and negative cff some of which are sensitive to the less well controlled slip distributions of the earliest historic events calculations also show that from 1981 until just before the 1992 landers earthquake more than 85 of small m 3 and micro size m 1 8 shocks in the seeber and armbruster 1995 catalog with mechanisms involving either nw trending right lateral or ne trending left lateral strike slip faulting occurred in regions of positive cff the ratio of encouraged to all small and micro size events reaches a high value of about 88 if an apparent coefficient of friction between 0 0 and 0 6 is used the highest percentage of earthquakes occurred in areas where stress is about 1 mpa above the 1812 baseline most 66 events occurred in regions of cff between 0 0 and 2 0 mpa the upper limit indicates that the approximate range of stress variation in the earthquake cycle is of the order of 2 0 mpa the fact that the locations of most moderate small and micro size earthquakes are still related to stress changes remaining from large historical events might be used to constrain slip distribution of some of those earthquakes and to constrain the locations of future significant events

temporal changes of shallow seismic velocity around the karadere duzce branch of the north anatolian fault and strong ground motion we analyze temporal variations of seismic velocity along the karadere duzce branch of the north anatolian fault using seismograms generated by repeating earthquake clusters in the aftershock zones of the 1999 mw7 4 izmit and mw7 1 duzce earthquakes the analysis employs 36 sets of highly repeating earthquakes each containing 4 18 events the events in each cluster are relocated by detailed multi step analysis and are likely to rupture approximately the same fault patch at different times the decay rates of the repeating events in individual clusters are compatible with the omori s law for the decay rate of regional aftershocks a sliding window waveform cross correlation technique is used to measure travel time differences and evolving decorrelation in waveforms generated by each set of the repeating events we find clear step like delays in the direct s and early s coda waves sharp seismic velocity reduction immediately after the duzce main shock followed by gradual logarithmic type recoveries a gradual increase of seismic velocities is also observed before the duzce main shock probably reflecting post seismic recovery from the earlier izmit main shock the temporal behavior is similar at each station for clusters at various source locations indicating that the temporal changes of material properties occur in the top most portion of the crust the effects are most prominent at stations situated in the immediate vicinity of the recently ruptured fault zones and generally decrease with normal distance from the fault a strong correlation between the co seismic delays and intensities of the strong ground motion generated by the duzce main shock implies that the radiated seismic waves produced the velocity reductions in the shallow material

analysis of cassini cirs limb spectra of titan acquired during the nominal mission i hydrocarbons nitriles and co2 vertical mixing ratio profiles observations of the composite infrared spectrometer cirs during the entire nominal cassini mission 2004 2008 provide us with an accurate global view of composition and temperature in the middle atmosphere of titan between 100 and 500 km we investigated limb spectra acquired at 0 5 cm 1 resolution at nine different latitudes between 56 s and 80 n with a better sampling in the northern hemisphere where molecular abundances and temperature present strong latitudinal variations from this limb data acquired between february 2005 and may 2008 we retrieved the vertical mixing ratio profiles of c2h2 c2h4 c2h6 c3h8 ch3c2h c4h2 c6h6 hcn hc3n and co2 we present here for the first time the latitudinal variations of the c2h6 c3h8 co2 c2h4 and c6h6 vertical mixing ratios profiles some molecules such as c2h6 or c3h8 present little variations above their condensation level the other molecules except co2 show a significant enhancement of their mixing ratios poleward of 50 n c2h4 is the only molecule whose mixing ratio decreases with height at latitudes below 46 n regions depleted in c2h2 hcn and c4h2 are observed around 400 km 0 01 mbar and 55 n we also inferred a region enriched in co2 located between 30 and 40 n in the 2 0 7 mbar pressure range at 80 n almost all molecules studied here present a local minimum of their mixing ratio profiles near 300 km 0 07 mbar which is in contradiction with global circulation models that predict constant with height vertical profiles due to subsidence at the north pole 2009 elsevier inc all rights reserved

systematic analysis of crustal anisotropy along the karadere duzce branch of the north anatolian fault s u m m a r y we perform a systematic analysis of crustal anisotropy along and around the karadere duzce branch of the north anatolian fault naf which ruptured during the 1999 mw 7 4 izmit and mw 7 1 duzce earthquakes a method consisting of an iterative grid search for the best shear wave splitting parameters in sliding time windows is applied to 22 000 measurements recorded in the 6 month period after the izmit main shock based on objective criteria 6600 measurements are assigned high quality and used for further detailed analysis most stations near the rupture zone have fast polarization directions that are parallel to and change with the nearby fault strike the average delay times for ray paths that propagate along the rupture zone are larger than for the other paths these results suggest the existence of an approximately 1 km broad zone around the karadere duzce branch with fault parallel cracks or shear fabric however some fault zone fz stations record bimodal or scattered polarization directions while stations near large structural complexities e g branching and offsets show average fast polarization directions that are almost perpendicular to the local fault strike the average fast polarization directions from ray paths that propagate inside the almacik block south of the karadere duzce branch are neither parallel to the local fault strike nor to the expected regional maximum compressive stress direction the large overall spatial variations of the results imply that multiple structures and mechanisms contribute to the observed crustal anisotropy in our study area most stations do not exhibit a clear dependency of shear wave splitting delay time with increasing depth and hypocentral distance indicating that the anisotropy is confined primarily to the top 3 4 km of the crust using the observed average delay time at fz stations and assumed propagation distance of 3 5 km we estimate the apparent crack density in the damaged shallow fz rock to be approximately 7 per cent

local observations of the onset of a large earthquake 28 june 1992 landers california the landers earthquake mw 7 3 of 28 june 1992 had a very emergent onset the first large amplitude arrivals are delayed by about 3 sec with respect to the origin time and are preceded by smaller scale slip other large earthquakes have been observed to have similar emergent onsets but the landers event is one of the first to be well recorded on nearby stations we used these recordings to investigate the spatial relationship between the hypocenter and the onset of the large energy release and to determine the slip function of the 3 sec nucleation process relative location of the onset of the large energy release with respect to the initial hypocenter indicates its source was between 1 and 4 km north of the hypocenter and delayed by approximately 2 5 sec three station array analysis of the p wave shows that the large amplitude onset arrives with a faster apparent velocity compared to the first arrivals indicating that the large amplitude source was several kilometers deeper than the initial onset an ml 2 8 foreshock located close to the hypocenter was used as an empirical green s function to correct for path and site effects from the first 3 sec of the mainshock seismogram the resultant deconvolution produced a slip function that showed two subevents preceding the main energy release an mw 4 4 followed by an mw 5 6 these subevents do not appear anomalous in comparison to simple moderate sized earthquakes suggesting that they were normal events which just triggered or grew into a much larger earthquake if small and moderate sized earthquakes commonly detonate much larger events this implies that the dynamic stresses during earthquake rupture are at least as important as long term static stresses in causing earthquakes and the prospects of reliable earthquake prediction from premonitory phenomena are not improved

dynamics of izmit earthquake postseismic deformation and loading of the duzce earthquake hypocenter we have developed dynamic finite element models of izmit earthquake postseismic deformation to evaluate whether this deformation is better explained by afterslip via either velocity strengthening frictional slip or linear viscous creep or by distributed linear viscoelastic relaxation of the lower crust we find that velocity strengthening frictional afterslip driven by coseismic shear stress loading can reproduce time dependent global positioning system data better than either linear viscous creep on a vertical shear zone below the rupture or lower crustal viscoelastic relaxation our best frictional afterslip model fits the main features of postseismic slip inversions in particular high slip patches at and below the hypocenter and on the western karadere segment and limited afterslip west of the hersek delta burgmann et al 2002 the model requires a weakly velocity strengthening fault that is either low effective normal stress in the slipping regions or a smaller value for the parameter describing rate dependence of friction a b than is indicated by laboratory experiments our best afterslip model suggests that the coulomb stress at the duzce hypocenter increased by 0 14 mpa 1 4 bars during the izmit earthquake assuming right lateral slip on a surface dipping 50 to the north and by another 0 1 mpa during the 87 days between the izmit and duzce earthquakes in the marmara sea region within about 160 km of the izmit earthquake rupture this model indicates that the coulomb stresses increased by 15 25 of the coseismic amount during the first 300 days after the earthquake three hundred days after the earthquake postseismic contributions to coulomb stressing rate on the maramara region faults had fallen to values equal to or less than the inferred secular stress accumulation rate our estimates of postseismic coulomb stress are highly model dependent in the marmara region the linear viscous shear zone and viscoelastic lower crust models predict greater postseismic coulomb stresses than the frictional afterslip model near field stress and fault zone rheology estimates are sensitive to the earth9s elastic structure when a layered elastic structure is incorporated in our model it yields a coulomb stress of 0 24 mpa at the duzce hypocenter significantly more than the 0 14 mpa estimated from the uniform elastic model because of the higher near field coseismic stresses the layered elastic model requires a higher value of velocity strengthening parameter a b a b times effective normal stress r to produce comparable postseismic slip a b is estimated at 0 4 and 0 2 mpa respectively for the layered and uniform elastic models these results highlight the importance of understanding the earth9s elastic structure and the mechanism for postseismic deformation if we wish to accurately model coseismic and postseismic crustal stresses

finite fault analysis of the 1979 march 14 petatlan mexico earthquake using teleseismic p waveforms summary vertical teleseismic p waves recorded for the 1979 march 14 petatlan mexico earthquake were used to derive the distribution of coseismic slip using a linear finite fault inversion scheme that solves for the amount of slip in each of a series of consecutive time windows data recorded by six stations of the global digital seismograph network were inverted in addition to digitized analogue long period recordings available from nine worldwide standardized seismograph network stations the digital data include four broad band and short period velocity waveforms reconstructed from the short and long period components the time window approach allows for a variable rise time on the fault and accounts for the source multiplicity evident in the recorded p waveforms synthetic tests conducted using the inversion method on the limited data set however reveal that the data are insufficient to identify the exact dislocation duration on the fault the method is thus implemented by prescribing the fault rise time using five consecutive 1 s time windows the coseismic slip inferred from the p waves shows a small 70 cm peak near the earthquake hypocentre and a large zone of dislocation 1 2 m maximum further south east the slip pattern covers depths from 3 to 25 km and is located south east of other recent large interplate ruptures on the michoacan segment of the mexican subduction zone this result indicates that the 1979 petatlan earthquake broke an independent adjacent portion of the cocos north america plate boundary the seismic moment of 1 5 1027 dyn cm inferred from the p waves is approximately one half the long period moment estimated by other investigators from the observed surface waves although the discrepancy is within the uncertainty of the seismic moment estimates it may suggest the presence of a component of slow interplate motion that did not radiate significant p wave energy

the structure of venus middle atmosphere and ionosphere esa s venus express probe has been in orbit since april 2006 eight research papers in this issue present new results from the mission covering the atmosphere polar features interactions with the solar wind and the controversial matter of venusian lightning hakan svedham et al open the section with a review of the similarities and mostly differences between venus and its twin the earth andrew ingersoll considers the latest results and also how the project teams plan to make the most of the probe s remaining six years of life radio sounding results from the first venus express radio science vera occultation season are reported which determine the fine structure in temperatures at upper cloud deck altitudes detect a distinct day night temperature difference in the southern middle atmosphere and track day to day changes in venus ionosphere the atmosphere and ionosphere of venus have been studied in the past by spacecraft with remote sensing1 2 3 4 or in situ techniques3 4 these early missions however have left us with questions about for example the atmospheric structure in the transition region from the upper troposphere to the lower mesosphere 50 90 km and the remarkably variable structure of the ionosphere observations become increasingly difficult within and below the global cloud deck 50 km altitude where strong absorption greatly limits the available investigative spectrum to a few infrared windows and the radio range here we report radio sounding results from the first venus express radio science5 vera occultation season we determine the fine structure in temperatures at upper cloud deck altitudes detect a distinct day night temperature difference in the southern middle atmosphere and track day to day changes in venus ionosphere

kinematics of the mw 7 2 12 november 1999 duzce turkey earthquake the november 12 1999 duzce earthquake ruptured a 40 km long fault segment of the north anatolian fault system immediately to the east of the august 17 1999 izmit rupture we use displacements of 32 sites derived from gps measurements immediately before and after the duzce earthquake to estimate the geometry and slip distribution of the coseismic rupture the 51 northward dipping rupture plane the rake of the slip vector average 3 76 0 04 m right lateral 0 76 0 04 m normal slip and the slip distribution inferred from the gps data are consistent with seismic observations and the distribution of surface offsets measured in the field the geodetically determined moment magnitude is mw 7 2 the duzce earthquake had the highest slip to rupture length ratio of any historic earthquake along the north anatolian fault this is consistent with the duzce earthquake being a part of a composite rupture with the preceding izmit event

planetary scale waves and the cyclic nature of cloud top dynamics on venus abstract pioneer venus ocpp ultraviolet images spanning eight years have been analyzed objectively to derive quantitative information on the properties of planetary scale wave modes at the venus cloud tops we infer propagation characteristics for longitudinal wavenumber 1 by fourier analyzing time series of longitudinal mean normalized image brightness the dominant equatorial mode during 1979 80 was the 4 day periodicity associated with zonal motion of the y feature the difference between this and the 4 7 day equatorial rotation period derived from the tracking of small cloud features implies that the y is a propagating wave with a prograde phase speed of about 15 ms 1 relative to the wind simultaneous time series of cloud tracked wind fluctuations also exhibit a 4 day periodicity lending support to the wave interpretation the prograde propagation and equatorial confinement of the wave and the absence of analogous meridional wind fluctuations identify it as a kelvin wave zonal winds peak near the

influence of venus topography on the zonal wind and uv albedo at cloud top level the role of stationary gravity waves based on the analysis of uv images at 365 nm of venus cloud top altitude 67 2 km collected with vmc venus monitoring camera on board venus express vex it is found that the zonal wind speed south of the equator from 5 s to 15 s shows a conspicuous variation from 101 to 83 m s with geographic longitude of venus correlated with the underlying relief of aphrodite terra we interpret this pattern as the result of stationary gravity waves produced at ground level by the up lift of air when the horizontal wind encounters a mountain slope these waves can propagate up to the cloud top level break there and transfer their momentum to the zonal flow such upward propagation of gravity waves and influence on the wind speed vertical profile was shown to play an important role in the middle atmosphere of the earth by lindzen 1981 but is not reproduced in the current gcm of venus atmosphere from lmd in the equatorial regions the uv albedo at 365 nm varies also with longitude we argue that this variation may be simply explained by the divergence of the horizontal wind field in the longitude region from 60 to 10 where the horizontal wind speed is increasing in magnitude stretch it triggers air upwelling which brings the uv absorber at cloud top level and decreases the albedo and vice versa when the wind is decreasing in magnitude compression this picture is fully consistent with the classical view of venus meridional circulation with upwelling at equator revealed by horizontal air motions away from equator the longitude effect is only an additional but important modulation of this effect this interpretation is comforted by a recent map of cloud top h2o fedorova et al 2015 showing that near the equator the lower uv albedo longitude region is correlated with increased h2o we argue that h2o enhancement is the sign of upwelling suggesting that the uv absorber is also brought to cloud top by upwelling

a complex seismogenic shear zone the duzce segment of north anatolian fault turkey abstract this work highlights how surface geological data can integrate and complete a fault characterization including its seismogenic depth we investigated the area struck by the november 1999 mw 7 1 earthquake that ruptured the duzce segment of the north anatolian fault zone nafz after the august 1999 mw 7 4 izmit earthquake to explore the persistency or evolution of the active fault setting at the surface we compared detailed coseismic surface expressions with the long term morphology and structural architecture of the duzce zone we identified a simple 1999 coseismic fault trace cft and an older complex fault system rfs involving a wider zone of deformation two different parts of the duzce segment were recognized a western section presents a staircase trajectory of the coseismic fault trace that reactivated part of the older fault system an eastern section presents a straight coseismic fault trace that cross cuts the older and complex fault system the western duzce fault segment splays out from the izmit counterpart of the nafz forming a releasing fault junction by comparing a model of its coseismic surface deformation field with the long term morphology we observed that the present topography of this western section results from the nafz activity by repeating coseismic deformations like those in 1999 the mechanical interaction in the release fault junction produces local transtension across the western duzce fault and justifies its stable complexity it does not evolve into a straight trace the surface boundary between the duzce fault sections also separates at depth two fault sections one with low slip to the west and another with a big asperity to the east thus the izmit duzce interaction 1 may produce an unfavorable setting for a build up of asperities in the western duzce segment and 2 could delay the propagation of the izmit rupture along the duzce segment that nucleates mainshocks only on its eastern section in other words the arrangement of the fault junction may permanently control how the two sections of the duzce fault behave and rupture

variations of sulphur dioxide at the cloud top of venus s dynamic atmosphere a pulse of sulphur dioxide in venus s upper atmosphere was observed by the pioneer venus spacecraft in the 1970s and 1980s and attributed to volcanism recent sulphur dioxide measurements from venus express indicate decadal scale fluctuations in sulphur dioxide above venus s cloud tops in an atmosphere that is more dynamic than expected

moment constrained finite fault analysis using teleseismic p waves mexico subduction zone abstract we examine the ability of teleseismic p waves to identify the rupture history of large earthquakes along the mexico subduction zone using a kinematic finite fault waveform inversion scheme that uses the earthquake seismic moment to stabilize the inversion process application of our procedure to the teleseismic displacement waveforms recorded for the m w 7 9 colima jalisco earthquake of october 1995 yields a slip pattern that is similar to the rupture model derived previously using a more traditional approach that incorporates stepwise adjustments to the constraint equations to recover the least complicated source model the areas of large slip inferred for both models are located at the same general position along the fault although peak slips obtained using the moment constrained approach are significantly greater synthetic tests conducted for a hypothetical interplate rupture along the guerrero portion of the mexico subduction zone indicate that the high peak slips result from a wide variability in slip amplitude for individual subfaults although the variability is less pronounced when velocity waveforms are used in the inversion the tests also show that errors in fault dip and earthquake nucleation depth affect the accuracy of the inferred slip source more significantly than errors in strike and rake also the data are relatively insensitive to variations in rupture velocity and dislocation duration suggesting that our single step approach could be used in a simplified manner to identify the first order rupture features of large earthquakes using routinely derived fault parameters a simplified analysis of the p wave ground velocities recorded for the m w 7 5 tecoman colima earthquake of january 2003 yields a slip distribution that is remarkably similar to a rupture model derived previously using teleseismic body waves and strong motion records

importance of model parameterization in finite fault inversions application to the 1974 mw 8 0 peru earthquake the spatial and temporal slip distributions for the october 3 1974 mw 8 0 peru subduction zone earthquake and its largest aftershock on november 9 ms 7 1 are calculated and analyzed in terms of the inversion parameterization and tectonic significance teleseismic long period world wide standard seismograph network p and sh waveforms are inverted to obtain the rupture histories we demonstrate that erroneous results are obtained if a parameterization is used that does not allow for a sufficiently complex source involving spatial variation in slip amplitude risetime and rupture time the inversion method utilizes a parameterization of the fault that allows for a discretized source risetime and rupture time well located aftershocks recorded on a local network have the same general pattern as teleseismically determined hypocenters and help to constrain the geometry of the subduction zone for the main shock a hinged fault is preferred having a shallow plane with a dip of 11 and a deeper landward plane with a dip of 30 the preferred nucleation depth lies between 11 and 15 km a bilateral rupture is obtained with two major concentrations of slip one 60 to 70 km to the northwest of the epicenter and a second 80 to 100 km to the south and southeast of the epicenter for these source regions risetimes vary from 6 to 18 s our estimates of risetimes are consistent with the time for the rupture to traverse the dominant local asperity the slip distribution for the november 9 aftershock falls within a conspicuous hole in the main shock rupture pattern near the hypocenter of the main shock the november 9 event has a simple risetime function with a duration of 2 s aftershocks recorded by the local network are shown to cluster near the hypocenter of the impending november 9 event and downdip from the largest main shock source region slip during the main shock is concentrated at shallow depths above 15 km and extends updip from the hypocenter to near the plate boundary at the trench axis the large amount of slip at shallow depths is attributed to the absence of any significant accretionary wedge of sediments and the relatively young age and high convergence rate of the subducted plate which results in good seismic coupling near the trench axis

active volcanism on venus in the ganiki chasma rift zone venus is known to have been volcanically resurfaced in the last third of solar system history and to have undergone a significant decrease in volcanic activity a few hundred million years ago however fundamental questions remain is venus still volcanically active today and if so where and in what geological and geodynamic environment here we show evidence from the venus express venus monitoring camera for transient bright spots that are consistent with the extrusion of lava flows that locally cause significantly elevated surface temperatures the very strong spatial correlation of the transient bright spots with the extremely young ganiki chasma their similarity to locations of rift associated volcanism on earth provide strong evidence for their volcanic origin and suggests that venus is currently geodynamically active

atmospheric structure and dynamics as the cause of ultraviolet markings in the clouds of venus details about the atmosphere on venus are gradually emerging from the once apparently impenetrable global cloud cover simultaneous imaging in the ultraviolet and infrared by venus express provides a new view of the ultraviolet patterns seen in the cloud tops the picture that emerges is one of dark low latitudes dominated by convective mixing in the sulphuric acid clouds bringing unknown ultraviolet absorbers up from the lower atmosphere the cloud top morphology revealed in the southern hemisphere by venus express resembles that found earlier by pioneer venus and venera 15 in the north suggesting global symmetry between the two hemispheres when seen in ultraviolet light venus has contrast features that arise from the non uniform distribution of unknown absorbers within the sulphuric acid clouds this paper reports multi wavelength imaging that reveals that the dark low latitudes are dominated by convective mixing that brings the ultraviolet absorbers up from depth the bright and uniform mid latitude clouds reside in the cold collar which suppresses vertical mixing in low and middle latitudes the visible cloud top is located at a constant altitude of 72 1 km in both the ultraviolet dark and bright regions indicating that the brightness variations result from compositional differences caused by the colder environment when seen in ultraviolet light venus has contrast features that arise from the non uniform distribution of unknown absorbers within the sulphuric acid clouds1 2 3 and seem to trace dynamical activity in the middle atmosphere4 it has long been unclear whether the global pattern arises from differences in cloud top altitude which was earlier3 estimated to be 66 72 km compositional variations or temperature contrasts here we report multi wavelength imaging that reveals that the dark low latitudes are dominated by convective mixing which brings the ultraviolet absorbers up from depth the bright and uniform mid latitude clouds reside in the cold collar an annulus of cold air characterized by 30 k lower temperatures with a positive lapse rate which suppresses vertical mixing and cuts off the supply of ultraviolet absorbers from below in low and middle latitudes the visible cloud top is located at a remarkably constant altitude of 72 1 km in both the ultraviolet dark and bright regions indicating that the brightness variations result from compositional differences caused by the colder environment rather than by elevation changes the cloud top descends to 64 km in the eye of the hemispheric vortex which appears as a depression in the upper cloud deck the ultraviolet dark circular streaks enclose the vortex eye and are dynamically connected to it

comparison of seismic waveform inversion results for the rupture history of a finite fault application to the 1986 north palm springs california earthquake the july 8 1986 north palm springs earthquake is used as a basis for comparison of several different approaches to the solution for the rupture history of a finite fault the inversion of different waveform data is considered both teleseismic p waveforms and local strong ground motion records linear parametrizations for slip amplitude are compared with nonlinear parametrizations for both slip amplitude and rupture time inversions using both synthetic and empirical green s functions are considered in general accurate green s functions are more readily calculable for the teleseismic problem where simple ray theory and flat layered velocity structures are usually sufficient however uncertainties in the variation in t with frequency most limit the resolution of teleseismic inversions a set of empirical green s functions that are well recorded at teleseismic distances could avoid the uncertainties in attenuation in the inversion of strong motion data the accurate calculation of propagation path effects other than attenuation effects is the limiting factor in the resolution of source parameters the assumption of a laterally homogeneous velocity structure is usually not a good one and the use of empirical green s functions is desirable considering the parametrization of the problem any degree of fault rupture complexity can be described in terms of a linear parametrization for slip amplitudes however a nonlinear parametrization for rupture times and slip amplitudes can have a distinct advantage over a simple linear one by limiting the number of unknown parameters regardless of the choice of data or the type of parametrization the model or solution will be affected by the choice of minimization norm and the type of stabilization used

a rupture model for the 1967 mudurnu valley turkey earthquake and its implication for seismotectonics in the western part of the north anatolian fault zone six destructive earthquakes had successively occurred from 1939 to 1967 along the north anatolian fault zone the july 22 1967 mudurnu valley earthquake ms 7 1 was the last of this series with its western neighbour remaining as a seismic gap surface ruptures associated with this earthquake appeared within a broad shear zone extending to a distance of 80 km the generated teleseismic body waves were so complex that they were different even at stations in the same azimuth in this study we inverted the observed teleseismic body waves to investigate such a presumably complicated rupture process of the mudurnu valley earthquake we could identify six subevents within 2 minutes with their total seismic moment amounting to 1 1 1020 nm although right lateral strike slip faulting was found to be dominant two minor subevents had a dip slip mechanism one showed a reverse faulting mechanism and the other a normal faulting mechanism

perturbation of the izmit earthquake aftershock decaying activity following the 1999 mw 7 2 duzce turkey earthquake triggering and quiescence patterns of seismicity in western turkey following the occurrence of the 12 november 1999 m w 7 2 duzce earthquake are investigated the changes in seismicity rate are analyzed along the north anatolian fault segments that had ruptured 3 months earlier during the 17 august 1999 m w 7 4 izmit earthquake detection of triggering and quiescence is done by comparing the seismicity rate that would be expected if the duzce earthquake had not happened to the actual observed rate the expected rates are estimated by extrapolating the preexisting seismicity pattern using two complementary models a simple omori utsu s law and the etas model fault segments located to the east of the izmit epicenter show a mild case of quiescence following the duzce earthquake these segments had previously experienced an anomalous triggering episode in the 5 days preceding the duzce earthquake correlated with the occurrence of two strong m w 5 izmit aftershocks however it is not clear whether this observed quiescence is real or spurious as it coincides with a local reconfiguration of the seismological network a temporary increase of 0 1 to 0 15 in completeness magnitude would be enough to explain this apparent deactivation fault segments located to the west of the izmit epicenter exhibit triggering of seismicity following the duzce earthquake this observed triggering is mostly restricted to a cluster of events located in the geothermal area of yalova the increase of seismicity rate is delayed by 18 hours after the waves travelling from the duzce rupture had hit this zone our analysis suggests that this 15 day long reactivation can be explained by a short lived perturbation the local seismic activity then sustaining itself for the remaining 15 days we argue that this particular behavior is likely to correspond to a case of dynamic triggering by the end of year 1999 the yalova cluster shows a significant quiescence that lasted for several months this shutting down does not coincide with the occurrence of any local earthquake that would be large enough to stress shadow this area suggesting an aseismic cause to this pattern these results highlight the fact that 1 seismicity triggered by a major earthquake is not restricted to areas loaded by static stress and 2 that seismic activity associated with geothermal geological settings is highly sensitive to stress perturbations but also to aseismic processes that can both delay reactivation and cause this activity to suddenly decrease

seismic hazard in the marmara sea region following the 17 august 1999 izmit earthquake on 17 august 1999 a destructive magnitude 7 4 earthquake occurred 100 km east of istanbul near the city of izmit on the north anatolian fault this 1 600 km long plate boundary 1 2 slips at an average rate of 2 3 cm yr 1 refs 3 5 and historically has been the site of many devastating earthquakes 6 7 this century alone it has ruptured over 900 km of its length 6 models of earthquake induced stress change 8 combined with active fault maps 9 had been used to forecast that the epicentral area of the 1999 izmit event was indeed a likely location for the occurrence of a large earthquake 9 10 here we show that the 1999 event itself significantly modifies the stress distribution resulting from previous fault interactions 9 10 our new stress models take into account all events in the region with magnitudes greater than 6 having occurred since 1700 ref 7 as well as secular interseismic stress change constrained by gps data 11 these models provide a consistent picture of the long term spatio temporal behaviour of the north anatolian fault and indicate that two events of magnitude equal to or greater than the izmit earthquake are likely to occur within the next decades beneath the marmara sea south of istanbul

a procedure for modelling shallow dislocation sources summary expressions for displacements on the surface of a layered half space due to an arbitrary oriented shear dislocation are given in terms of generalized ray expansions useful approximations of these expressions for shallow events as recorded at teleseismic distances for realistic earth models are presented the results of this procedure are used to generate synthetic p sv and sh waveforms for various assumptions of stress drop

slip distribution and stress changes associated with the 1999 november 12 duzce turkey earthquake mw 7 1 the 1999 november 12 duzce earthquake m w 7 1 was apparently the eastward extension of the august 17 izmit earthquake m w 7 4 the duzce event caused heavy damage and fatalities in the cities of duzce and bolu here a finite fault inversion method with five discrete time windows is applied to derive the co seismic slip distribution of the duzce earthquake the fault plane is best modelled as a 40 x 20 km 2 plane with a strike of 262degrees and a dip of 65degrees to the north and that the majority of slip occurred in two distinct patches on either side of the hypocentre implying bilateral rupture the possible triggering of this event by the izmit earthquake is investigated using coulomb stress modelling of all large events since 1943 with the inclusion of secular loading the results show that although the duzce rupture plane was in a stress shadow prior to the izmit earthquake that event caused a significant coulomb stress load taking the duzce fault out of the stress shadow which probably precipitated failure a comparison of the mapped coulomb stress change with the inferred slip shows no correlation between the two finally the stress modelling indicates that the northern branch of the north anatolian fault zone beneath the sea of marmara towards the city of istanbul is presently the most highly loaded segment of the north anatolian fault zone

chemical record of the projectile in the graded fall back sedimentary unit from the ries crater germany abstract the so called graded unit comprises 17 2 m of the core from the research borehole nordlingen 1973 and is thought to represent fall back material which has been sorted similar to tephra samples from six levels of these air borne impact debris sediments in the ries crater have been analyzed for ir ni co cr and fe the concentrations of these elements are negatively correlated with average grain size and accordingly the depth of the samples indicating the presence of a surface correlated component and are hence consistent with vapour deposition of meteoritic material on small dust grains the largest ir concentration found is 230 pg g a factor of 28 higher than the indigenous concentration enrichment factors in the uppermost layer of the graded unit are about 28 for ir approximately 2 for fe co ni and 1 5 for cr if the enrichment of all elements determined were of meteoritic origin then the net meteoritic composition is most closely matched by aubrites as suggested previously however it seems more likely that the observed concentration trends of cr fe co and ni are due to mineral sorting therefore the only as yet certain indication of meteoritic material is the presence of ir which is not sufficient to further constrain the nature of the projectile

surface processes recorded by rocks and soils on meridiani planum mars microscopic imager observations during opportunity s first three extended missions the microscopic imager mi on the mars exploration rover opportunity has returned images of mars with higher resolution than any previous camera system allowing detailed petrographic and sedimentological studies of the rocks and soils at the meridiani planum landing site designed to simulate a geologist s hand lens the mi is mounted on opportunity s instrument arm and can resolve objects 0 1 mm across or larger this paper provides an overview of mi operations data calibration and analysis of mi data returned during the first 900 sols mars days of the opportunity landed mission analyses of opportunity mi data have helped to resolve major questions about the origin of observed textures and features these studies support eolian sediment transport rather than impact surge processes as the dominant depositional mechanism for burns formation strata mi stereo observations of a rock outcrop near the rim of erebus crater support the previous interpretation of similar sedimentary structures in eagle crater as being formed by surficial flow of liquid water well sorted spherules dominate ripple surfaces on the meridiani plains and the size of spherules between ripples decreases by about 1 mm from north to south along opportunity s traverse between endurance and erebus craters

slip distribution along the north anatolian fault associated with the large earthquakes of the period 1939 to 1967 abstract between 1939 and 1967 six large fault ruptures formed a westward migrating sequence of events along a 900 km long nearly continuous portion of the north anatolian fault for these events the 1939 erzincan 1942 niksar erbaa 1943 tosya 1944 bolu gerede 1957 abant and 1967 mudurnu valley earthquakes i have compiled a record of dextral slip which contains nearly 100 points these data indicate that the amount of slip is irregularly distributed along the 1939 to 1967 rupture zone the maximum slip 7 5 m occurred during the 1939 earthquake in the eastern 150 km of the 900 km long rupture zone dextral offsets diminish very abruptly eastward but very gradually westward the rate of westward decrease in the 1939 to 1967 offsets is only slightly greater than the rate of westward decrease of post miocene displacement along the north anatolian fault this suggests that westward decrease in slip can be expected to be a general characteristic of earthquake ruptures along the north anatolian fault in the future nevertheless within the 1939 to 1967 slip distribution there are three regions that had less slip than the neighboring regions these i interpret as possible sites of large future earthquakes one of these seismic gaps has already experienced another earthquake in 1951 and subsequent creep

deformation during the 12 november 1999 duzce turkey earthquake from gps and insar data only 87 days after the mw 7 5 17 august 1999 izmit earthquake the duzce earthquake ruptured a ca 40 km long adjoining strand of the north anatolian fault naf system to the east we used displacements of 50 global positioning system gps sites together with interferometric synthetic aperture radar insar range change data spanning the event to estimate the geometry and slip distribution of the coseismic rupture postseismic deformation transients from the duzce earth quake and the preceding i zmit event that are included in some of the measurements are corrected for using dislocation models fit to gps data spanning the various time periods nonlinear inversions for fault geometry indicate that the rupture occurred on a ca 54 north dipping oblique normal right lateral fault distributed slip inver sions indicate maximum strike slip near the center of the duzce fault close to the earthquake hypocenter slip magnitude and depth of faulting decrease to the west and east of the hypocenter both gps and insar data suggest that normal slip is restricted to the shallow portion of the rupture the duzce earthquake had the highest slip to rupture length ratio of any historic earthquake along the naf

broadband ground motion simulation within the city of duzce turkey and building response simulation in areas with significant seismic activity and insufficient seismic networks simulated ground motions are required for both seismic hazard and engineering analyses one important task is evaluating the efficiency of the simulated records in building response estimation in this study a hybrid ground motion simulation framework is presented to obtain broadband ground motion time histories of a past major earthquake in duzce turkey the hybrid ground motion simulation framework presented herein is a combination of a discrete wavenumber finite element method for simulating low frequencies and a stochastic finite fault method for the higher frequencies the proposed technique is first validated by the simulation of the 12 november 1999 duzce earthquake m text w 7 1 which occurred in the north anatolian fault zone turkey peak simulated ground motions at selected nodes are then compared against ground motion prediction equations derived with global and local data sets next the spatial distribution of simulated peak ground motion intensities are obtained in the region and compared with the observed damage distribution results demonstrate that the earthquake is simulated effectively despite the limitations in number of stations and velocity models finally to evaluate the simulated records in building response estimation nonlinear time history analyses of three reinforced concrete multi degree of freedom structures are performed with real and simulated records of the 1999 duzce earthquake in the opensees platform the results reveal that reasonable predictions can be made regarding the dynamic response of structures using the records simulated with the approach presented herein

triggered slip observations of the 17 august 1999 izmit turkey earthquake using radar interferometry we use synthetic aperture radar interferometry insar to map the displacement field of the 17 august 1999 izmit earthquake which largely conforms to that predicted for an elastic upper crust we determine the earthquake source parameters and show that slip continues farther west than the mapped fault ruptures we also show that additional sub surface displacements occurred on parallel strands of the north anatolian fault zone we argue that this was caused by changes in static stress accompanying the mainshock or by the dynamic release of regional stresses

coseismic ruptures and tectonic landforms along the duzce segment of the north anatolian fault zone ms 7 1 november 1999 1 this paper presents a comparison between the pattern of surface ruptures produced by a single earthquake and patterns of cumulative deformation we performed a detailed study of the 1999 earthquake coseismic ruptures and of the long term tectonic landforms in a key area of the duzce fault segment of the north anatolian fault we observed a scale independent en echelon arrangement of the coseismic surface ruptures as a whole the long term geomorphic expression of the duzce fault near the 1999 ruptures is evidence of the principal slip zone at depth that accommodates the bulk of the displacement during an individual rupture event this may stay localized through many rupture episodes with persistent geometry and kinematics the long term tectonic and geomorphic expression of the fault in a broader area around the 1999 ruptures defines a wider deformation zone in fact an old and complex fault arrangement has been mapped partially coinciding with the 1999 rupturing fault suggesting that the 1999 ruptures are an incomplete expression of the long term duzce fault system the relationships between the coseismic and the old fault systems suggest an evolution of the fault pattern trough time with a tendency to simplify a geometric complexity into a straighter mature trace the integrated investigation of long term tectonic morphologies and structural pattern offers a noteworthy frame to interpret the coseismic rupture kinematics and clarifies their complexities moreover to fully understand the principal slip zone at depth this work shows the importance of the study of strain distribution pattern and evolution of surface rupturing faults

wide band analysis of the 3 march 1985 central chile earthquake overall source process and rupture history we apply a linear finite fault waveform inversion scheme to the near source strong motion records the teleseismic body waves and the long period rayleigh waves recorded for the 3 march 1985 chile earthquake to recover the mainshock rupture history the data contain periods between about 2 and 350 sec and are inverted by allowing a variable dislocation rise time at each point on the fault the results indicate that the mainshock had a seismic moment of 1 5 1028 dyne cm mw 8 0 and ruptured mainly updip and to the south of the hypocenter for a distance of about 150 km along the nazca south america plate boundary a smaller northward component of propagation is also evident giving a total rupture length of about 200 km the total source duration of the mainshock is 70 sec with the majority of the slip occurring within the first 40 sec in a broad 100 km wide zone in the northern half of the rupture area slip in this region extends from a depth of 55 km to within about 10 km of the surface and contains two areas of maximum slip 2 3 and 2 9 m with rise times of approximately 14 sec slip in the southern portion of the fault reaches lower peak values 1 8 m and extends downdip to depths no greater than 30 km an independent variable rise time inversion of the teleseismic body waves alone yields similar results indicating that a significant component of slow fault motion is not required for this earthquake the mainshock was preceded by several smaller precursors the largest of which is an mw 6 6 thrust earthquake occurring at a depth of 22 km in the shallow 15 dipping portion of the plate interface

m 7 earthquake rupture forecast and time dependent probability for the sea of marmara region turkey we forecast time independent and time dependent earthquake ruptures in the marmara region of turkey for the next 30 years using a new fault segmentation model we also augment time dependent brownian passage time bpt probability with static coulomb stress changes cff from interacting faults we calculate mw 6 5 probability from 26 individual fault sources in the marmara region we also consider a multisegment rupture model that allows higher magnitude ruptures over some segments of the northern branch of the north anatolian fault zone beneath the marmara sea a total of 10 different mw 7 0 to mw 8 0 multisegment ruptures are combined with the other regional faults at rates that balance the overall moment accumulation we use gaussian random distributions to treat parameter uncertainties e g aperiodicity maximum expected magnitude slip rate and consequently mean recurrence time of the statistical distributions associated with each fault source we then estimate uncertainties of the 30 year probability values for the next characteristic event obtained from three different models poisson bpt and bpt cff using a monte carlo procedure the gerede fault segment located at the eastern end of the marmara region shows the highest 30 year probability with a poisson value of 29 and a time dependent interaction probability of 48 we find an aggregated 30 year poisson probability of m 7 3 earthquakes at istanbul of 35 which increases to 47 if time dependence and stress transfer are considered we calculate a twofold probability gain ratio time dependent to time independent on the southern strands of the north anatolian fault zone

rupture process of the 1992 erzincan earthquake and its implication for seismotectonics in eastern turkey the 13 march 1992 erzincan earthquake is different from the previous earthquakes which have occured along the north anatolian fault zone nafz in that no surface rupture was observed in order to infer a rupture process of this earthquake we inverted the teleseismic body waves to the source using the method of kikuchi and kanamori 1991 three different subevents were then distinguished with total seismic moment of mo 1 2 1026 dyn cm the major energy release was found to be during the first subevent with seismic moment of mo 9 4 1025 dyn cm rupture length of 30 km slip amount of 0 7 m and stress drop of 25 bars the second subevent was right lateral as was the case for the first one with a normal faulting component it was located 10 km to the southeast from the first one at the intersection of the right lateral nafz with the left lateral ovacik fault the third subevent with a right lateral mechanism was 10 km to the southeast from the second one these results are in good harmony with regional seismotectonics in eastern turkey

stress coupling between earthquakes in northwest turkey and the north aegean sea we have investigated the coulomb stress interactions of 29 earthquakes m s greater than or equal to 6 0 that have occurred in the region of northwest turkey and north aegean sea since 1912 of these events 23 may be related to earlier events and 16 are clearly related to earlier events all events after 1967 are related to previous events events in the early part of our time interval that show no correlation could be related to historical events as yet unidentified in some cases faults that have received a stress reduction from earlier events are prepared for an event by an earthquake occurring a few years before that creates a local coulomb stress rise thus regions of coulomb stress shadow can become regions where a damaging earthquake may occur the relation between smaller events and the coulomb stress distribution is less clear but may be related to poor data quality and practical limitations of our modeling technique nonetheless there are 4 times as many events per unit area in regions of enhanced stress than where stress is reduced we discuss the contemporary distribution of coulomb stress and argue that it is possible to identify the likely locations of future damaging earthquakes including identifying the most likely candidate faults

a pyroclastic flow deposit on venus explosive volcanism on venus is severely inhibited by its high atmospheric pressure and lack of water this paper shows that a deposit located near 16 s 144 e here referred to as scathach fluctus displays a number of morphological characteristics consistent with a pyroclastic flow deposit these characteristics particularly its lack of channelisation and evidence for momentum rather than cooling limited flow length contrast with fissure fed lava flow deposits the total erupted volume is estimated to have been between 225 km3 and 875 km3 but this may have been emplaced in more than one event interaction between scathach fluctus and a small volcanic cone constrain the flow velocity to 48 m s 1 and plausible volatile concentrations to at least 1 8 wt h2o 4 3 wt co2 or 6 1 wt so2 the latter two implying magma sourced directly from the mantle the deposit has radar characteristics particularly an exponential backscatter function that are similar to those of nearly half the planetary surface implying that pyroclastic deposits may be much more common on venus than has been recognised to date and suggesting both a relatively volatile rich mantle and a volcanic source for atmospheric so2

active tectonics of the alpine himalayan belt between western turkey and pakistan summary over 80 new fault plane solutions combined with satellite imagery as well as both modern and historical observations of earthquake faulting are used to investigate the active tectonics of the middle east between western turkey and pakistan the deformation of the western part of this region is dominated by the movement of continental material laterally away from the lake van region in eastern turkey this movement helps to avoid crustal thickening in the van region and allows some of the shortening between arabia and eurasia to be taken up by the thrusting of continental material over oceanic type basement in the southern caspian mediterranean makran and black sea thus central turkey bounded by the north and east anatolian strike slip faults is moving west from the van region and overrides the eastern mediterranean at two intermediate depth seismic zones one extending between antalya bay and southern cyprus and the other further west in the hellenic trench the motion of northern iran eastwards from the van region is achieved mainly by a conjugate system of strike slip faults and leads to the low angle thrusting of iran over the southern caspian sea the seismicity of the caucasus shows predominantly shortening perpendicular to the regional strike but there is also some minor elongation along the strike of the belt as the causcasus overrides the caspian and black seas the deformation of the eastern part of this region is dominated by the shortening of iran against the stable borders of turkmenistan and afghanistan the north east direction of compression seen in zagros is also seen in north east iran and the kopet dag where the shortening is taken up by a combination of strike slip and thrust faulting large structural as well as palaeomagnetic rotations are likely to have occurred in ne iran as a result of this style of deformation north south strike slip faults in southern iran allow some movement of material away from the collision zone in ne iran towards the makran subduction zone where genuinely intermediate depth seismicity is seen within this broad deforming belt large areas such as central turkey nw iran azerbaijan central iran and the southern caspian appear to be almost aseismic and therefore to behave as relatively rigid blocks surrounded by active belts 200 300 km wide the motion of these blocks can usefully be described by poles of rotation the poles presented in this paper predict motions consistent with those observed and also predict the opening of the gulf of iskenderun ne of cyprus the change within the zagros mountains from strike slip faulting in the nw to intense thrusting in the se and the relatively feeble seismicity in se iran baluchistan this description also explains why the north south structures along the iran afghanistan border do not cut the east west ranges of the makran within the active belts surrounding the relatively aseismic blocks a continuum approach is needed for a description of the deformation even though motions at the surface may be concentrated on faults the evolution of fault systems within the active zones is controlled by geometric constraints such as the requirement that simultaneously active faults do not in general intersect many of the active processes discussed in this paper particularly large scale rotations and lateral movement along the regional strike are likely to have caused substantial complexities in older mountain belts and should be accounted for in any reconstructions of them

surface rupture and slip distribution of the 12 november 1999 duzce earthquake m 7 1 north anatolian fault bolu turkey the 12 november 1999 earthquake m 7 1 occurred on the duzce fault a splay of the north anatolian fault in the bolu basin approximately three months after the 17 august 1999 m 7 4 earthquake the surface rupture was 40 km long and the maximum right lateral offset was 500 5 cm averaging 300 cm the 9 km of the westernmost part of the rupture along the southern margin of the eften lake had a 350 cm maximum vertical displacement normal faulting some of which was already ruptured during the 17 august 1999 event with few tens of centimeters the surface rupture has a generally simple narrow deformation zone of 0 5 5 m however in some places it widens to 50 m transtensional and transpressional structures were observed within releasing and restraining step over areas respectively the larger dextral offsets on some streams indicate previous events the dextral slip measurements along the rupture reflect a symmetric distribution the eastern connection of this rupture zone with the main trace of north anatolian fault remains unclear because the bakacak and elmalik fault which are connecting faults had no surface rupture manuscript received 14 november 2000

new constraints on micro seismicity and stress state in the western part of the north anatolian fault zone observations from a dense seismic array with the aim of extensively investigating the crustal structure beneath the western segment of the north anatolian fault zone where it splays into northern and southern branches a temporary seismic network dense array for north anatolia dana consisting of 70 stations was deployed in early may 2012 and operated for 18 months in the sakarya region during the faultlab experiment out of 2437 events contaminated by explosions we extracted 1371 well located earthquakes the enhanced station coverage having a nominal station spacing of 7 km lead to a minimum magnitude calculation of 0 1 horizontal and vertical location uncertainties within the array do not exceed 0 8 km and 0 9 km respectively we observe considerable seismic activity along both branches of the fault where the depth of the seismogenic zone was mostly confined to 15 km using our current earthquake catalog we obtained a b value of 1 we also mapped the b value variation with depth and observed a gradual decrease furthermore we determined the source parameters of 41 earthquakes with magnitudes greater than 1 8 using p wave first motion polarity method regional moment tensor inversion method was also applied to earthquakes with magnitudes greater than 3 0 focal mechanism solutions confirm that sakarya and its vicinity is stressed by a compressional regime showing a primarily oblique slip motion character stress tensor analysis indicates that the maximum principal stress is aligned in wnw ese direction and the tensional axis is aligned in nne ssw direction

rupture processes of the 1999 august 17 izmit and november 12 duzce turkey earthquakes summary we derive the rupture history of the 1999 august 17 izmit mw 7 4 and 1999 november 12 duzce mw 7 1 earthquakes in turkey from teleseismic body waves using broad band data of the global seismograph network aftershock locations and mapped surface breaks the centroid solutions indicate strike slip mechanisms for both events the izmit earthquake was characterized by rupture propagating predominantly eastwards it consisted of a main rupture lasting about 25 s followed within 1 min by two more events of mw 6 9 and mw 7 0 with the teleseismic data we could not resolve the westward extent of rupture into the marmara sea however an upper bound of the seismic moment release west of the epicentre of the izmit event is estimated to be 1 9 1019 n m the duzce earthquake lasted about 14 s and was characterized by a bilateral mode of rupture in excellent agreement with mapped surface breaks and aftershock locations

joint inversion of insar gps teleseismic and strong motion data for the spatial and temporal distribution of earthquake slip application to the 1999 izmit mainshock the space time distribution of slip of the 17 august 1999 izmit earthquake is investigated by inverting synthetic aperture radar sar interferometry and global positioning system gps data together with teleseismic broadband and near field strong motion records surface offsets are used as an added constraint special emphasis is given to analysis of the resolution of the different data sets we use a four segment finite fault model and a nonlinear inversion scheme allowing slip to vary in amplitude direction and duration as well as variable rupture velocity from the inversion of synthetic data we find that the best spatial resolution can be expected in the upper half of the fault model above 12 km where coverage of the interferometric sar data is good western half of the rupture and near the gps and strong motion stations teleseismic data are found to have a lower resolution that is more evenly distributed over the fault model the joint inversion of all the data sets has an increased resolving power compared with the separate inversions and gives a more robust description of the space and time distribution of slip our study shows the importance of resolution tests in evaluating the reliability of earthquake kinematic models and it confirms that an excellent fit of a single kind of data does not necessarily imply a good retrieval of the kinematic properties of an earthquake the izmit rupture which is almost pure right lateral strike slip faulting is dominated by the bilateral breaking of a central asperity located between 29 7 e about 10 km west of the city of golcuk and 30 4 e eastern margin of sapanka lake with slip reaching 6 8 m in the depth range 6 12 km the western termination of the rupture is found near the city of yalova but large slip ends around 29 7 e about 10 km east of hersek delta a second area of large slip is required by all the data sets further east toward the city of duzce between 30 7 e and 31 1 e karadere and duzce faults this eastern slip zone which is separated from the main central asperity by an area of greatly reduced slip is less well constrained by the data however a strong motion station near the city of duzce helps to locate a high slip patch near 31 1 e in the depth range 6 12 km the total seismic moment resulting from the joint inversion is 2 4 1027 dyne cm most of the energy release occurred in a short time less than 15 sec corresponding to the bilateral breaking of the central asperity rupture propagation is relatively uniform and fast toward the west with a rupture velocity close to 3 5 km sec propagation of large slip toward the east is initially slower but it accelerates during a short time interval about 10 sec after rupture nucleation eastward progression then slows down to less than 2 km sec after 15 sec and rupture almost vanishes in amplitude ca 20 sec after initiation rupture propagation then proceeds on the easternmost karadere and duzce fault segments east of 30 7 e from 22 to ca 50 sec supershear rupture propagation is not required for modeling the waveforms considered in this study the hypocenter of the duzce earthquake which occurred 3 months later 12 november 1999 m w 7 2 is located in the immediate vicinity of the easternmost slip patch of the izmit earthquake manuscript received 28 july 2000

what controls an earthquake s size results from a heterogeneous cellular automaton the controls on an earthquake s size are examined in a heterogeneous cellular automaton that includes stress concentrations which scale with rupture size large events only occur when stress is highly correlated with strength over the entire fault although the largest events occur when this correlation is the highest the magnitude of the correlation has no predictive value as events of all magnitudes occur during times of high stress strength correlation rather the size of any particular event depends on the local stress heterogeneity encountered by the growing rupture patterns of energy release with time for individual ruptures reflect this heterogeneity and many show nucleation type behaviour although there is no relation between the duration of nucleation phase and the size of the event these results support the view that earthquake size is determined by complex interactions between previous event history and dynamic stress concentrations and suggest that deterministic earthquake prediction based on monitoring nucleation zones will not be possible

source rupture process of the kocaeli turkey earthquake of august 17 1999 obtained by joint inversion of near field data and teleseismic data the rupture process of the 1999 turkey earthquake is examined using both near field strong motion data and teleseismic body wave data the derived source parameters are as follows strike dip slip 268 86 180 nearly pure strike slip the seismic moment mo 1 7 1020 nm mw 7 4 the source duration 20 sec the fault length 70 km the fault width 15 km the rupture process is characterized by an asymmetric bilateral rupture propagation and smooth slip it consists of two major fault segments a rupture propagating to the west and a second rupture propagating to the east the maximum dislocation and the maximum dislocation velocity are 6 3 m and 2 7 m s respectively both found at the former segment the average dislocation is about 4 m the extent of the coseismic rupture suggests that a considerable part of the anticipated seismic gap remains unruptured

seismic activity triggered by the 1999 izmit earthquake and its implications for the assessment of future seismic risk summary a serious question has remained as to the location of the western end of the main rupture zone associated with the 1999 izmit turkey earthquake a clear answer to this question is extremely important for the assessment of future seismic risk in the eastern marmara sea region turkey in this paper we show an effective approach to answering this important question unifying different kinds of information such as seismic activity focal mechanism solutions and stress changes caused by the main shock into a clear image we first point out that the major moment release is 1 6r10 20 n m and covered the area between 29 7ue and 30 5ue and we then claim that the enhanced seismic activity after the main shock in the eastern marmara sea region should be regarded as activity triggered by the increase of stress rather than as aftershock activity along the ruptured zone we propose three fault segments with an average stress increase on each in the western extension of the main shock rupture zone as potential sites for future large earthquakes namely i the 50 km long yalova hersek segment 0 45 mpa ii the nw setrending right lateral strike slip fault known as the princes islands segment 0 18 mpa

stochastic strong ground motion simulation of the 12 november 1999 duzce turkey earthquake using a dynamic corner frequency approach on 12 november 1999 only three months after the 17 august 1999 kocaeli earthquake mw 7 4 an earthquake of mw 7 1 occurred immediately to the east of the kocaeli rupture in northwestern turkey resulting in extensive structural damage in the city of duzce and its surrounding area it was reported to be a right lateral strike slip event on the previously unbroken segment of the north anatolian fault zone with a north dipping fault plane this paper presents stochastic finite fault simulation of near field ground motions from this earthquake at selected near fault stations based on a dynamic corner frequency approach using the computer program exsim motazedian and atkinson 2005 the method requires region specific source path and site characterizations as input model parameters the source mech anism of the 1999 duzce event and regional path effects are well constrained from previous studies of the earthquake the local site effects at the selected stations are studied as a combination of the kappa operator and frequency dependent soil ampli fication the model parameters are validated against recordings and a stress drop value of 100 bars is estimated for the 1999 duzce earthquake the validated model is then used to compute synthetic records around the fault distribution of peak ground motion parameters is observed to be consistent with the building damage dis tribution in the near fault region most affected by the seismic shaking the attenuation of synthetic ground motion parameters is compared with recent ground motion pre diction equations proposed for the region by gulkan and kalkan 2002 ulusay et al 2004 and akkar and bommer 2007 as well as two next generation attenuation models by boore and atkinson 2007 and campbell and bozorgnia 2007 despite discrepancies at several stations stochastic finite fault modeling based on a dynamic corner frequency approach confirms to be a practical tool to reproduce the ground motions of large earthquakes

rupture distribution of the 1977 western argentina earthquake abstract teleseismic p and sh body waves are used in a finite fault waveform inversion for the rupture history of the 23 november 1977 western argentina earthquake this double event consists of a smaller foreshock mo 5 3 1026 dyn cm followed about 20 s later by a larger main shock mo 1 5 1027 dyn cm our analysis indicates that these two events occurred on different fault segments with the foreshock having a strike dip and average rake of 345 45 e and 50 and the main shock 10 45 e and 80 respectively the foreshock initiated at a depth of 17 km and propagated updip and to the north the main shock initiated at the southern end of the foreshock zone at a depth of 25 to 30 km and propagated updip and unilaterally to the south the north south separation of the centroids of the moment release for the foreshock and main shock is about 60 km the apparent triggering of the main shock by the foreshock is similar to other earthquakes that have involved the failure of multiple fault segments such as the 1992 landers california earthquake such occurrences argue against the use of individual mapped surface fault or fault segment lengths in the determination of the size and frequency of future earthquakes

spatial and temporal distribution of slip for the 1992 landers california earthquake we have determined a source rupture model for the 1992 landers earthquake m w 7 2 compatible with multiple data sets spanning a frequency range from zero to 0 5 hz geodetic survey displacements near field and regional strong motions broadband teleseismic waveforms and surface offset measurements have been used explicitly to constrain both the spatial and temporal slip variations along the model fault surface our fault parameterization involves a variable slip multiple segment finite fault model which treats the diverse data sets in a self consistent manner allowing them to be inverted both independently and in unison the high quality data available for the landers earthquake provide an unprecedented opportunity for direct comparison of rupture models determined from independent data sets that sample both a wide frequency range and a diverse spatial station orientation with respect to the earthquake slip and radiation pattern in all models consistent features include the following 1 similar overall dislocation patterns and amplitudes with seismic moments of 7 to 8 10 26 dyne cm seismic potency of 2 3 to 2 7 km 3 2 very heterogeneous unilateral strike slip distributed over a fault length of 65 km and over a width of at least 15 km though slip is limited to shallower regions in some areas 3 a total rupture duration of 24 sec and an average rupture velocity of 2 7 km sec and 4 substantial variations of slip with depth relative to measured surface offsets the extended rupture length and duration of the landers earthquake also allowed imaging of the propagating rupture front with better resolution than for those of prior shorter duration strike slip events our imaging allows visualization of the rupture evolution including local differences in slip durations and variations in rupture velocity rupture velocity decreases markedly at shallow depths as well as near regions of slip transfer from one fault segment to the next as rupture propagates northwestward along the multiply segmented fault length the rupture front slows as it reaches the northern limit of the johnson valley landers faults where slip is transferred to the southern homestead valley fault an abrupt acceleration is apparent following the transfer this process is repeated and is more pronounced as slip is again passed from the northern homestead valley fault to the emerson fault although the largest surface offsets were observed at the northern end of the rupture our modeling indicates that substantial rupture was also relatively shallow less than 10 km in this region

evolution of the stress field in southern california and triggering of moderate size earthquakes a 200 year perspective changes in stress in southern california are modeled from 1812 to 2025 using as input 1 stress drops associated with six large 7 0 7 5 earthquakes through 1995 and 2 stress buildup associated with major faults with slip rates 3 mm yr as constrained by geodetic paleoseismic and seismic measurements evolution of stress and the triggering of moderate to large earthquakes are treated in a tensoffal rather than a scalar manner we present snapshots of the cumulative coulomb failure function acff as a function of time for faults of various strike dip and rake throughout southern california we take acff to be zero everywhere just prior to the great shock of 1812 we find that about 95 of those well located m 6 earthquakes whose mechanisms involve either strike slip or reverse faulting are consistent with the coulomb stress evolutionary model that is they occurred in areas of positive acff the interaction between slow moving faults and stresses generated by faster moving faults significantly advanced the occurrence of the 1933 long beach and 1992 landers events in their earthquake cycles coulomb stresses near major thrust faults of the western and central transverse ranges have been accumulating for a long time future great earthquakes along the san andreas fault especially if the san bernardino and coachella valley segments rupture together can trigger moderate to large earthquakes in the transverse ranges as appears to have happened in the santa barbara earthquake that occurred 13 days after the great san andreas shock of 1812 maps of current acff provide additional guides to long term earthquake prediction

global positioning system constraints on plate kinematics and dynamics in the eastern mediterranean and caucasus we present and interpret global positioning system gps measurements of crustal motions for the period 1988 1997 at 189 sites extending east west from the caucasus mountains to the adriatic sea and north south from the southern edge of the eurasian plate to the northern edge of the african plate sites on the northern arabian platform move 18 2 mm yr at n25 5 w relative to eurasia less than the nuvel 1a circuit closure rate 25 1 mm yr at n21 7 w preliminary motion estimates 1994 1997 for stations located in egypt on the northeastern part of africa show northward motion at 5 6 2 mm yr also slower than nuvel ia estimates 10 1 mm yr at n2 4 e eastern turkey is characterized by distributed deformation while central turkey is characterized by coherent plate motion internal deformation of 2 mm yr involving westward displacement and counterclockwise rotation of the anatolian plate the anatolian plate is de coupled from eurasia along the right lateral strike slip north anatolian fault naf we derive a best fitting euler vector for anatolia eurasia motion of 30 7 0 8 n 32 6 0 4 e 1 2 0 1 myr the euler vector gives an upper bound for naf slip rate of 24 1 mm yr we determine a preliminary gps arabia anatolia euler vector of 32 9 1 2 n 40 3 1 1 e 0 8 0 2 myr and an upper bound on left lateral slip on the east anatolian fault eaf of 9 1 mm yr the central and southern aegean is characterized by coherent motion internal deformation of 2 mm yr toward the sw at 30 1 mm yr relative to eurasia stations in the se aegean deviate significantly from the overall motion of the southern aegean showing increasing velocities toward the trench and reaching 10 1 mm yr relative to the southern aegean as a whole

a methodology for seismic loss estimation in urban regions based on ground motion simulations seismic vulnerability assessment of residential buildings in regions of high seismicity is an interdisciplinary problem requiring major inputs from fields of seismology and earthquake engineering the basic two components of loss estimation methods are information on regional seismicity and building stock this study presents a realistic loss estimation methodology where the first component input ground motions is obtained from regional ground motion simulations using the stochastic finite fault technique the second component building vulnerability information on the other hand is taken into account using fragility analyses introducing the ground motion intensity parameters obtained from simulations to the fragility curves we obtain seismic loss distribution in a region in this study we demonstrate the loss estimation methodology with an application to three northwestern cities in turkey duzce bolu and kaynasli that experienced two major earthquakes graphic 1 and graphic 2 in less than three months in 1999 we initially verify the methodology with comparisons of observed and estimated damage ratios for the 12 november 1999 graphic 3 duzce earthquake later we present the estimated damage ratios under scenario earthquakes in the region for a magnitude range of graphic 4 graphic 5 is predicted to be the threshold magnitude for the cities of duzce and kaynasli where more than 60 of the building stock experience moderate and heavy damage because bolu is at a farther distance from the fault plane less damage is estimated for graphic 6 than those in the other centers for graphic 7 all three cities are predicted to experience substantial rates of heavy damage and collapse 1 embed inline graphic 1 gif 2 embed inline graphic 2 gif 3 embed inline graphic 3 gif 4 embed inline graphic 4 gif 5 embed inline graphic 5 gif 6 embed inline graphic 6 gif 7 embed inline graphic 7 gif

altimetry of the venus cloud tops from the venus express observations 1 simultaneous observations of venus by visible and infrared thermal imaging spectrometer and venus monitoring camera onboard the venus express spacecraft are used to map the cloud top altitude and to relate it to the ultraviolet uv markings the cloud top altitude is retrieved from the depth of co2 absorption band at 1 6 m in low and middle latitudes the cloud top is located at 74 1 km it decreases poleward of 50 and reaches 63 69 km in the polar regions this depression coincides with the eye of the planetary vortex at the same latitude and hour angle cloud top can experience fast variations of about 1 km in tens of hours while larger long term variations of several kilometers have been observed only at high latitudes uv markings correlate with the cloud altimetry however the difference between adjacent uv dark and bright regions does not exceed several hundred meters surprisingly co2 absorption bands are often weaker in the dark uv features indicating that these clouds may be a few hundred meters higher or have a larger scale height than neighboring clouds ultraviolet dark spiral arms which are often seen at about 70 correspond to higher altitudes or to the regions with strong latitudinal gradient of the cloud top altitude cloud altimetry in the polar region reveals the structure that correlates with the thermal emission maps but is invisible in uv images this implies that the uv optically thick polar hood is transparent in the near ir

adjacent releases of mantle helium and soil co2 from active faults observations from the marmara region of the north anatolian fault zone turkey volatile releases in terms of co2 efflux and noble gas of mantle origin are investigated in the marmara region of the seismically active north anatolian fault naf zone a total of 180 co2 efflux measurements 1 to 309 g m 2d 1 were carried out along four transects across the naf spatial variability of surface co2 effluxes was higher at faulted sites relative to comparable background areas the 13c values of soil co2 are 24 0 to 15 6 without correlation with co2 efflux values which suggest that co2 efflux anomaly is caused by fault related biogenic gas flow furthermore 36 gas and water samples from spring sites were investigated for 3he 4he ratios which resulted in a range from 0 26 r ra to 4 22 r ra large mantle helium contributions were observed from several sources along the naf the high co2 efflux sector on the gazikoy saros fault along the naf coincides with the area of high mantle helium flux this shows that fault zones play an important role both in transferring mantle helium to the surface and in causing fault related biogenic gas flow

an investigation of the so2 content of the venusian mesosphere using spicav uv in nadir mode using the spicav uv spectrometer aboard venus express in nadir mode we were able to derive spectral radiance factors in the middle atmosphere of venus in the 170 320 nm range at a spectral resolution of r 200 during 2006 and 2007 in the northern hemisphere by comparison with a radiative transfer model of the upper atmosphere of venus we could derive column abundance above the visible cloud top for so2 using its spectral absorption bands near 280 and 220 nm so2 column densities show large temporal and spatial variations on a horizontal scale of a few hundred kilometers typical so2 column densities at low latitudes up to 50 n were found between 5 and 50 m atm whereas in the northern polar region so2 content was usually below 5 m atm the observed latitudinal variations follow closely the cloud top altitude derived by spicav ir and are thought to be of dynamical origin also a sudden increase of so2 column density in the whole northern hemisphere has been observed in early 2007 possibly related to a convective episode advecting some deep so2 into the upper atmosphere

the 17 august 1999 izmit earthquake on 17 august 1999 an earthquake of magnitude 7 4 shook northwestern turkey details on the earthquake9s characteristics and effects across northwestern turkey are provided and are put in the historical context of previous earthquakes in the region the earthquake was the seventh in a series of earthquakes migrating westwards along the north anatolian fault since 1939 information on historical earthquakes modeling and estimates of the slip rate along the fault indicate that the location and severity of the earthquake should not have come as a surprise

inversion of strong ground motion and teleseismic waveform data for the fault rupture history of the 1979 imperial valley california earthquake a least squares point by point inversion of strong ground motion and teleseismic body waves is used to infer the fault rupture history of the 1979 imperial valley california earthquake the imperial fault is represented by a plane embedded in a half space where the elastic properties vary with depth the inversion yields both the spatial and temporal variations in dislocation on the fault plane for both right lateral strike slip and normal dip slip components of motion inversions are run for different fault dips and for both constant and variable rupture velocity models effects of different data sets are also investigated inversions are compared which use the strong ground motions alone the teleseismic body waves alone and simultaneously the strong ground motion and teleseismic records the inversions are stabilized by adding both smoothing and positivity constraints the moment is estimated to be 5 0 10 25 dyne cm and the fault dip 90 5 dislocation in the hypocentral region south of the united states mexican border is relatively small and almost dies out near the border dislocation then increases sharply north of the border to a maximum of about 2 m under interstate 8 dipslip motion is minor compared to strike slip motion and is concentrated in the sediments the best fitting constant rupture velocity is 80 per cent of the local shear wave velocity however there is a suggestion that the rupture front accelerated from the hypocenter northward the 1979 imperial valley earthquake can be characterized as a magnitude 5 earthquake at the hypocenter which then grew into or triggered a magnitude 6 earthquake north of the border

strike slip fault geometry in turkey and its influence on earthquake activity the geometry of turkish strike slip faults has been reviewed and described from this data set it appears that fault geometry the distribution of discontinuities such as bends and stepovers along the main fault trace plays an important role in controlling the location of large earthquake rupture segments along the fault zones large earthquake ruptures generally do not propagate past individual stepovers that are wider than 5 km or bends that have angles greater than about 30 more important than the size of each discontinuity however is the total geometric pattern i e the distribution of adjacent bends and stepovers based not only on distance from one another but also on relative discontinuity size certain geometric patterns restraining single or double bends are particularly common and can be viewed as responsible for strain accumulation along portions of the fault zone fault geometry not only plays a role in the extent of earthquake rupture but also in characteristics of earthquake behavior for example large earthquake epicenters often occur near restraining bends or double bends furthermore aftershocks and swarm activity can often be associated with releasing areas areas along the strike slip fault that are undergoing a relatively large amount of extension

coseismic and early post seismic slip associated with the 1999 izmit earthquake turkey from sar interferometry and tectonic field observations summary we use combined tectonic field observations and sar data to determine an improved model of the slip associated with the 1999 izmit earthquake which ruptured the north anatolian fault at the eastern end of the sea of marmara the leading goal is to understand the main features of the coseismic and post seismic deformation which are captured together in the sar data to achieve this we make a critical analysis of the ers1 2 sar data which allows atmospheric effects to be identified and removed we also use detailed field mapping and measurements of the earthquake surface rupture dislocations in elastic half space and a forward modelling strategy allow us to obtain a slip model by steps a trial and error approach is combined with conventional inversion techniques to determine the slip in the different regions of the fault the sar data are well explained with three main zones of high slip along the fault releasing a total moment of 2 3 10 20 nm mw 7 6 which is higher than the seismological estimates 1 7 2 0 10 20 n m the inhomogeneous slip distribution correlates with fault segments identified at the surface the izmit rupture appears to have extended 30 km west of the hersek peninsula into the sea of marmara with slip tapering fro m2mt ozero the western end of the rupture is located 40 km sse from istanbul we show that some features seen near to mudurnu and gevye and previously interpreted as slip on secondary faults are explained mostly as atmospheric effects correlated with the topography using our approach and the available gps data we obtain a slip model that represents the coseismic slip alone which suggests that the moment release during the main shock was 1 9 10 20 nm mw 7 5 consistent with the seismological estimates we conclude that the sar data include the effects of 2 m of fast after slip during the month following the main shock within a zone of the fault located 12 24 km below the epicentral region near the hypocentre at a depth of 18 km the fault appears to have experienced dynamic slip of 1 m associated with the main shock followed by 2 m of rapidly decelerating post seismic shear during the following month we suggest that the distribution of heterogeneous slip and loading along the different fault segments may be important factors controlling the propagation of large earthquake ruptures along the north anatolian fault

analysis of izmit aftershocks 25 days before the november 12th 1999 duzce earthquake turkey abstract we investigate spatial clustering of 2414 aftershocks along the izmit mw 7 4 august 17 1999 earthquake rupture zone 25 days prior to the duzce earthquake mw 7 2 november 12 1999 we analyze two spatial clusters namely sakarya sc and karadere duzce kdc we determine the earthquake frequency magnitude distribution b value for both clusters we find two high b value zones in sc and one high b value zone in kdc which are in agreement with large coseismic surface displacements along the izmit rupture the b values are significantly lower at the eastern end of the izmit rupture where the duzce mainshock occurred these low b values at depth are correlated with low postseismic slip rate and positive coloumb stress change along kdc since low b values are hypothesized with high stress levels we propose that at the depth of the duzce hypocenter 12 5 km earthquakes are triggered at higher stresses compared to shallower crustal earthquake the decrease in b value from the karadere segment towards the duzce basin supports this low b value high stress hypothesis at the eastern end of the izmit rupture consequently we detect three asperity regions which are correlated with high b value zones along the izmit rupture according to aftershock distribution the half of the duzce fault segment was active before the 12 november 1999 duzce mainshock this part is correlated with low b values which mean high stress concentration in the duzce basin this high density aftershock activity presumably helped to trigger the duzce event mw 7 2 after the izmit mw 7 4 mainshock

spatiotemporal variations of crustal anisotropy from similar events in aftershocks of the 1999 m7 4 izmit and m7 1 duzce turkey earthquake sequences summary we analyse spatiotemporal variations of crustal anisotropy along the karadere duzce branch of the north anatolian fault from similar earthquakes in the aftershock regions of the 1999 mw7 4izmit and mw7 1 duzce earthquakes the similar earthquake clusters are identified by performing cross correlation on waveforms generated by 18 000 earthquakes depending on the applied similarity criterion about 4 60 per cent of the events belong to similar event clusters splitting parameters averaged within each cluster show significant variations for slightly different ray paths indicating strong spatial variations of crustal anisotropy in this area we also find clear changes in the spatiotemporal seismicity patterns following the duzce main shock large apparent co seismic changes up to 30 per cent of shear wave splitting delay times are observed across the time of the duzce main shock at stations near the epicentral region however the changes can be mostly explained by the spatial variations of ray paths due to the changing seismicity rather than changes in the properties of the anisotropic medium splitting parameters measured within similar earthquake clusters indicate at most 2 per cent changes in delay times associated with the occurrence of the duzce main shock the results do not show systematic precursory changes before the duzce main shock

atmospheric thermal structure and cloud features in the southern hemisphere of venus as retrieved from virtis vex radiation measurements thermal structure and cloud features in the atmosphere of venus are investigated using spectroscopic nightside measurements recorded by the visible and infrared thermal imaging spectrometer virtis aboard esa s venus express mission in the moderate resolution infrared mapping channel m ir 1 5 m new methodical approaches and retrieval results for the northern hemisphere have been recently described by haus et al haus r kappel d arnold g 2013 planet space sci 89 77 101 http dx doi org 10 1016 j pss 2013 09 020 now southern hemisphere maps of mesospheric temperature and cloud parameter fields are presented that cover variations with altitude latitude local time and mission time measurements from the entire usable data archive are utilized comprising radiation spectra recorded during eight venus solar days between april 2006 and october 2008 zonal averages of retrieved temperature altitude profiles in both hemispheres are very similar and give evidence of global n s axial symmetry of atmospheric temperature structure cold collar and warmer polar vortex regions exhibit the strongest temperature variability with standard deviations up to 8 5 k at 75 s and 63 km altitude compared with about 1 0 k at low and mid latitudes above 75 km the mesospheric temperature field strongly depends on local time at altitudes above about 75 km the atmosphere is warmer in the second half of night while the dawn side at lower altitudes is usually colder than the dusk side by about 8 k local minimum temperature of 220 k occurs at 03 00 h local time at 65 km and 60 s temperature standard deviation at polar latitudes is particularly large near midnight temperature variability with solar longitude is forced by solar thermal tides with a dominating diurnal component the influence of observed cloud parameter changes on retrieved mesospheric zonal average temperature structure is moderate and does not exceed 2 3 k at altitudes between 60 and 75 km the mesospheric thermal structure was essentially stable with julian date between 2006 and 2008 global n s axial symmetry is also observed in cloud structures cloud top altitude at 1 m slowly decreases from 71 km at the equator to 70 km at 45 50 and rapidly drops poleward of 50 it reaches 61 km over both poles average particle size in the vertical cloud column increases from mid latitudes toward the poles and also toward the equator resulting in minimum and maximum zonal average cloud opacities of about 32 and 42 and a planetary average of 36 5 at 1 m zonal averages of cloud features are similar at different solar days but variations with local time are very complex and inseparably associated with the superrotation of the clouds

heightened odds of large earthquakes near istanbul an interaction based probability calculation we calculate the probability of strong shaking in istanbul an urban center of 10 million people from the description of earthquakes on the north anatolian fault system in the marmara sea during the past 500 years and test the resulting catalog against the frequency of damage in istanbul during the preceding millennium departing from current practice we include the time dependent effect of stress transferred by the 1999 moment magnitude m 7 4 izmit earthquake to faults nearer to istanbul we find a 62 15 probability one standard deviation of strong shaking during the next 30 years and 32 12 during the next decade

stress accumulation and increased seismic risk in eastern turkey abstract unlike the north anatolian fault zone which has produced 11 large earthquakes since 1939 the east anatolian fault zone eafz has been relatively quiescent in the last century when compared to historical records and has therefore accumulated significant stresses along its length determination of the location and likely magnitude of a future probable earthquake along the eafz is of interest both because of this history of large earthquakes m 8 and the density of population in the area here we calculate stress evolution along the fault zone due to both seismic and tectonic loading since 1822 a sequence of 10 well constrained historical earthquakes is selected and the resulting stresses are calculated summed with tectonic loading stresses and resolved onto the mapped active faults we identify two areas of particular seismic risk one of which might be expected to yield a large event our results are sensitive to the previous history of large earthquakes in the region and indicate a need for detailed investigations to constrain the exact rupture geometries of previous earthquakes on these segments