dynamical properties of the venus mesosphere from the radio occultation experiment vera onboard venus express abstract the dynamics of venus mesosphere 60 100 km altitude was investigated using data acquired by the radio occultation experiment vera on board venus express vera provides vertical profiles of density temperature and pressure between 40 and 90 km of altitude with a vertical resolution of few hundred meters of both the northern and southern hemisphere pressure and temperature vertical profiles were used to derive zonal winds by applying an approximation of the navier stokes equation the cyclostrophic balance which applies well on slowly rotating planets with fast zonal winds like venus and titan the main features of the retrieved winds are a midlatitude jet with a maximum speed up to 140 15 m s 1 which extends between 20 s and 50 s latitude at 70 km altitude and a decrease of wind speed with increasing height above the jet cyclostrophic winds show satisfactory agreement with the cloud tracked winds derived from the venus monitoring camera vmc vex uv images although a disagreement is observed at the equator and near the pole due to the breakdown of the cyclostrophic approximation knowledge of both temperature and wind fields allowed us to study the stability of the atmosphere with respect to convection and turbulence the richardson number ri was evaluated from zonal field of measured temperatures and thermal winds the atmosphere is characterised by a low value of richardson number from 45 km up to 60 km altitude at all latitudes that corresponds to the lower and middle cloud layer indicating an almost adiabatic atmosphere a high value of richardson number was found in the region of the midlatitude jet indicating a highly stable atmosphere the necessary condition for barotropic instability was verified it is satisfied on the poleward side of the midlatitude jet indicating the possible presence of wave instability

imaging subduction from the trench to 300 km depth beneath the central north island new zealand with vp and vp vs summary recent dense deployments of portable digital seismographs have provided excellent control on earthquakes beneath the central north island of new zealand here we use a subset of the best recorded earthquakes in an inversion for the 3 d vp and vp vs structure the data set includes 39 123 p observations and 18 331 s observations from 1239 earthquakes and nine explosions the subducted plate is imaged as a high vp low vp vs feature vp within the mantle of the subducted slab is almost always 8 5 km s 1 which requires the ca 120 myr slab to be unusually cold the low vp vs within the subducted plate closely parallels the lower plane of the dipping seismic zone it most likely indicates fluid resulting from dehydration of serpentine in the slab mantle and the earthquakes themselves are likely to be promoted by dehydration embrittlement we identify a region with vp 8 0 km s 1 directly above the dipping seismic zone can be interpreted as sinking entrained with the motion of the subducted slab and forming a viscous blanket that insulates the slab from the high temperature mantle wedge material in the overlying low vp region can be interpreted as rising within a return flow within the wedge the volcanic front appears to be controlled by where this dipping low vp region meets the base of the crust the thickness of the backarc crust also shows significant variation along strike in the central taupo volcanic zone tvz the crust is ca 35 km thick while southwest of mt ruapehu the crust thickens by ca 10 km there is no significant low vp zone in the mantle wedge in this southwestern region suggesting that this thicker crust has choked off mantle return flow the seismic tomography results when combined with constraints on mantle flow from previous shear wave splitting results provide a plausible model for both the distribution of volcanism in the central north island and the exceptional magmatic productivity of the central tvz

characteristics of gravity waves generated by surface topography on venus comparison with the vega balloon results abstract data from the 1985 vega venus balloon mission indicate that the mountainous region known as aphrodite influences atmospheric motions at balloon float altitudes near 54 km an altitude located within the middle cloud region it is shown that stationary gravity waves generated by surface topography and doppler shifted by a wind blowing over the terrain can propagate upward to the middle cloud layers under the right circumstances waves are amplified considerably in excess of their amplification due to the decrease of density with altitude the additional amplification is due to resonance that results from variations of static stability and mean zonal wind with altitude computed atmospheric propagation characteristics combined with terrain slopes in aphrodite estimated from pioneer venus radar altimeter data can be sufficient to produce wind amplitudes at 54 km comparable to those observed by the vega 2 balloon as it overflew aphrodite the dominant waves have horizontal wavelengths of the ord

displacement accumulation from earthquakes on isolated normal faults abstract displacement profiles for isolated normal faults are most often triangular rather than semi elliptical as predicted for linear elastic materials simple modelling indicates that triangular displacement profiles can arise from gutenberg richter earthquakes randomly distributed on fault surfaces of constant dimensions near triangular profiles are generated after a small number of earthquake cycles and for earthquake magnitude ranges as small as 0 5 the results are only weakly dependent on the shape of earthquake slip profiles and reproduce the geometry of displacement profiles on the non propagating active cape egmont fault in new zealand by contrast growth models in which fault displacement and length increase in proportion result in unrealistic displacement profiles for realistic slip profiles irrespective of whether earthquake populations are characteristic or gutenberg richter

wave analysis in the atmosphere of venus below 100 km altitude simulated by the lmd venus gcm a new simulation of venus atmospheric circulation obtained with the lmd venus gcm is described and the simulated wave activity is analysed agreement with observed features of the temperature structure static stability and zonal wind field is good such as the presence of a cold polar collar diurnal and semi diurnal tides at the resolution used 96 longitudes 96 latitudes a fully developed superrotation is obtained both when the simulation is initialised from rest and from an atmosphere already in superrotation though winds are still weak below the clouds roughly half the observed values the atmospheric waves play a crucial role in the angular momentum budget of the venus s atmospheric circulation in the upper cloud the vertical angular momentum is transported by the diurnal and semi diurnal tides above the cloud base approximately 1 bar equatorward transport of angular momentum is done by polar barotropic and mid to high latitude baroclinic waves present in the cloud region with frequencies between 5 and 20 cycles per venus day periods between 6 and 23 earth days in the middle cloud just above the convective layer a kelvin type wave period around 7 3 ed is present at the equator as well as a low latitude rossby gravity type wave period around 16 ed below the clouds large scale mid to high latitude gravity waves develop and play a significant role in the angular momentum balance

dike intrusion and displacement accumulation at the intersection of the okataina volcanic centre and paeroa fault zone taupo rift new zealand abstract we examine the relationship between dike emplacement and normal fault displacement along the south western margin of okataina volcanic centre new zealand at this location dikes including a basaltic dike up to 5 m wide at the ground surface intruded during the 1886 ad tarawera eruption formed over the last 22 kyr in the tarawera linear vent zone within a few kilometres of the paeroa fault zone displacement analysis and mapping of fault scarps indicate that fault and dike extension are complementary over time periods of tens of thousands of years extension that is primarily accommodated by faulting outside the volcanic complex is achieved by dike intrusion and faulting within it historical observations following the 1886 ad eruption and previously published active fault trenching collectively indicate however that dike intrusion generally does not induce slip within the paeroa fault zone close to the lateral dike tip we suggest that displacement in the paeroa fault zone outside the okataina volcanic centre is generally not triggered by eruptions and that this fault is principally tectonic in origin

venus cloud level circulation during 1982 as determined from pioneer cloud photopolarimeter images ii solar longitude dependent circulation abstract a strong solar locked dependence of cloud level circulation is observed in the averaged cloud motions as well as in the ultraviolet reflectivity of the venus cloud layer as determined from pioneer venus orbiter images acquired during 1982 s s limaye c grassotti and m j kuetemeyer 1988 icarus 73 193 211 the cloud motions were determined by manually tracking cloud features while the ultraviolet reflectivity was determined by removing the scattering geometry dependence of the observed intensities in ultraviolet images of venus via a minnaert scattering model in low latitudes the average zonal component is slowest at about 10 40 am local solar time while the maximum poleward flow occurs at noon at most latitudes the cloud motions are divergent with the maximum horizontal divergence 5 10 6 sec 1 occurring in equatorial latitudes just past noon and become convergent at about 30 morning to 40 afternoon lat on both sides of the equator the lowest ultraviolet reflectivity is found near the equator at local noon peak reflectivity is found in broad tilted with respect to latitude circles bands near 45 lat in the north and south hemispheres an apparent relationship between the horizontal divergence and ultraviolet is indicated such that the highest reflectivities are found in regions of convergence in high latitudes and lower values where the motions are divergent in equatorial latitudes in solar locked coordinates the root mean square deviation of the normalized ultraviolet brightness is not uniformly distributed about the subsolar point but tends to be higher around 45 lat than in equatorial regions and over periods of about 2 weeks shows substantial small scale structure as well

holocene coastal evolution in a continental rift setting bay of plenty new zealand abstract the rangitaiki plain eastern bay of plenty new zealand is the geographic expression of an active continental back arc rift known as the taupo volcanic zone the rift is characterized by tectonic subsidence at rates of 0 4 2 0 mm year and is bounded by faults and marginal uplift at approximately 1 0 mm year since 6 5 ka the rangitaiki plain prograded at least 10 km due to volcanoclastic sediment supplied by three major rivers to reach its present location at about 1 8 ka at this time a linear coast was formed cliffed to the west in marine sediments and unwelded ignimbrites and extending as far east as a greywacke headland at whakatane in the tectonically subsiding rangitaiki plain an abundant supply of sediment overwhelms the tectonic control on coastal evolution further east a wide embayment at ohiwa remained little changed from 6 5 to ca 2 ka when the coastline in the plain prograded as far as the whakatane headland and longshore drift began to provide it with a substantial volume of sediment barrier spits formed rapidly and sedimentation has effectively closed and partially infilled the embayment ohiwa estuary despite its location in the actively uplifting margin of the continental rift remained submerged until sufficient sediment was available to contribute to the coastline straightening process the bay of plenty coastline is presently in a near equilibrium state

long term variation in the cloud tracked zonal velocities at the cloud top of venus deduced from venus express vmc images 1 we present observational evidence of the variation of the cloud tracked zonal velocity by 20 m s 1 with a timescale of a few hundred days in the southern low latitude region based on an analysis of cloud images taken by the venus monitoring camera on board venus express a spectral analysis suggests that the variation has a periodicity with a period of about 255 days although cloud features are not always passive tracers the periodical variation of the dynamical state is a robust feature superposed on this long term variation of the zonal velocity kelvin wave like disturbances tend to be observed in periods of relatively slow background velocity while rossby wave like disturbances tend to be observed in periods of fast background velocity since the momentum deposition by these waves can accelerate and decelerate the mean flow these waves may contribute to the suggested long term oscillation

winds in the middle cloud deck from the near ir imaging by the venus monitoring camera onboard venus express for more than 8 years the venus monitoring camera vmc onboard the venus express orbiter performed continuous imaging of the venus cloud layer in uv visible and near ir filters we applied the correlation approach to sequences of the near ir images at 965 nm to track cloud features and determine the wind field in the middle and lower cloud 49 57 km from the vmc images that spanned from december of 2006 through august of 2013 we derived zonal and meridional components of the wind field in low to middle latitudes 5 65 s the velocity of the retrograde zonal wind was found to be 68 70 m s the meridional wind velocity slowly decreases from peak value of 5 8 1 2 m s at 15 s to 0 at 65 70 s the mean meridional speed has a positive sign at 5 65 s suggesting equatorward flow this result together with the earlier measurements of the poleward flow at the cloud tops indicates the presence of a closed hadley cell in the altitude range 55 65 km long term variations of zonal and meridional velocity components were found during 1 200 earth days of observation at 20 5 s the zonal wind speed increases from 67 18 1 81 m s to 77 30 2 49 m s the meridional wind gradually increases from 1 30 1 82 m s to 8 53 2 14 m s following bertaux et al 2016 we attribute this long term trend to the influence from the surface topography on the dynamical process in the atmosphere via the upward propagation of gravity waves that became apparent in the vmc observations due to slow drift of the venus express orbit over aphrodite terra

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

superrotation of venus atmosphere analyzed with a full general circulation model 1 a general circulation model gcm has been developed for the venus atmosphere from the surface up to 100 km altitude based on the gcm developed for earth at our laboratory key features of this new gcm include topography diurnal cycle dependence of the specific heat on temperature and a consistent radiative transfer module based on net exchange rate matrices this allows a consistent computation of the temperature field in contrast to previous gcms of venus atmosphere that used simplified temperature forcing the circulation is analyzed after 350 venus days 111 earth years superrotation is obtained above roughly 40 km altitude below the zonal wind remains very small compared to observed values which is a major pending question the meridional circulation consists of equator to pole cells the dominant one being located within the cloud layers the modeled temperature structure is globally consistent with observations though discrepancies persist in the stability of the lowest layers and equator pole temperature contrast within the clouds 10 k in the model compared to the observed 40 k in agreement with observational data a convective layer is found between the base of the clouds around 47 km and the middle of the clouds 55 60 km altitude the transport of angular momentum is analyzed and comparison between the reference simulation and a simulation without diurnal cycle illustrates the role played by thermal tides in the equatorial region without diurnal cycle the gierasch rossow williams mechanism controls angular momentum transport the diurnal tides add a significant downward transport of momentum in the equatorial region causing low latitude momentum accumulation

solar locked and geographical atmospheric structures inferred from a venus general circulation model with radiative transfer abstract solar locked and geographical atmospheric structures of daily averaged wind and temperature on venus were investigated using an atmospheric general circulation model with venusian topography and a two stream radiative code and were compared with wind fields obtained from the akatsuki ultraviolet imager the horizontal wind fields simulated around the subsolar region are similar to the observed ones at the cloud top mid latitude jets of 120 m s 1 and an equatorial fast flow of 90 m s 1 are formed around the cloud top a poleward flow of 8 m s 1 is formed above the cloud layer where solar heating is strong around the cloud top a poleward flow of 1 m s 1 is confined within the equatorward flank of the jet core whereas an indirect circulation is formed in the jet core by the eddy heat fluxes owing to the thermal tide and baroclinic waves in solar fixed coordinates the subsolar to antisolar circulation is predominant around the cloud top thus differences are significant between the zonal and dayside averages of the meridional wind and its related fluxes within the cloud layer this suggests the zonal mean meridional wind of the hadley circulation eddy momentum and heat fluxes from the one side hemisphere must be estimated carefully in the experiment including topography a near surface subrotation is formed in latitudinal zones over high land and mountains a weakly stable layer is formed at 10 20 km at low latitudes and the zonal wind is weakened at the cloud top over the aphrodite terra regional stationary modification of the atmospheric structure due to topographical waves appears in the cloud layer

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

quaternary temporal stability of a regional strike slip and rift fault intersection abstract intersecting strike slip and normal fault systems form either two or three plate configurations in circumstances where they intersect to form a triple junction internal block deformation produces a quasi stable 3 d configuration permitting maintenance of both the regional geometry and kinematics of the intersection this paper examines the temporal stability of such a triple junction in new zealand over a range of timescales from individual earthquakes to millions of years and discusses the factors that impact its stability using seismic reflection gravity drill hole and outcrop data the accumulation of vertical displacements is examined both on individual faults and across the intersection zone between the strike slip north island fault system nifs and the taupo rift fault throws and throw rates for the nifs and taupo rift suggest that despite a three fold increase in throw rates in both fault systems at about 0 3 ma which may have modified the orientation of the slip vectors and therefore the contemporary kinematics of the triple junction the intersection of the two fault systems has functioned coherently for the last 0 6 1 5 myr accumulating vertical displacements interdependently since the early stages of rifting the apparent arrest of a large magnitude earthquake on the rift bounding fault adjacent to the intersection suggests that the short term dynamic behaviour of the system is relatively complex compared to the more coherent long term kinematics

crustal seismic reflection measurements across the northern extension of the taupo volcanic zone north island new zealand abstract a crustal seismic reflection profile across the offshore taupo volcanic zone otvz has been reprocessed to improve the lower crust upper mantle image the otvz is underlain by several strong sub horizontal crustal reflections that may correspond to shear zones or mafic sills a reflector interpreted to correspond to moho lies at a depth of about 8 8 5 s twt seconds two way traveltime about 20 km under the western margin of the raukumara peninsula and rises to a depth of about 6 s twt about 16 km under the active eastern part of the otvz and can be traced at about this depth across most of the otvz underlying this inferred moho are two diffuse zones of discontinuous reflectivity one underlying the active eastern otvz and a less well defined one underlying the landward extension of the havre trough they extend from about 15 to 35 km depth within the mantle wedge and are inferred to be imaging a zone of depleted upper mantle associated with crustal extension a localised zone of deep 30 50 km reflectivity and seismicity occurs under the eastern otvz margin and may relate to fluid flow from the hikurangi plateau being subducted further east

faulting and extension rate over the last 20 000 years in the offshore whakatane graben new zealand continental shelf oblique rifting in the offshore taupo volcanic zone new zealand is expressed in widely distributed active normal faulting in the 20 km wide whakatane graben active faults are identified along seafloor scarps and displacements of the post last glacial transgressive ravinement surface 400 faults we derive an extension rate at seismogenic depths 6 10 km across the graben of 13 6 mm yr by summing surface measurements assuming an average crustal fault dip of 45 15o and correcting for the discrepancies between surface and deep crustal extension estimates structural and kinematic data implies an extension direction 20o oblique to the rift axis resulting in up to 4 6 2 1 mm yr of dextral motion parallel to the rift axis the strike slip motion is accommodated by dip slip displacements on oblique faults in the centre of the graben and oblique slip faulting along the rift margins pure dip slip in the graben centre represents 50 of the total slip with the rangitaiki fault accommodating 25 of the total extension in the graben

analysis of late holocene faulting within an active rift using lidar taupo rift new zealand abstract high quality light detection and ranging lidar data collected across the rangitaiki plains the fastest extending section of the onshore taupo rift new zealand reveal 122 active fault traces and provide new constraints on displacements displacement rates and paleoearthquakes of the normal faults in the rift the identified lineaments are scarps that record vertical offset of geomorphic surfaces e g beach ridges meander channel floors river terraces etc and trend parallel or sub parallel to other active faults in the rift these lineaments are interpreted to be active faults active fault traces trend 060 and their lengths range from 0 25 to 6 km they mainly traverse and displace a diachronous landscape of

shallow structure and active tectonism of an offshore continental back arc spreading system the taupo volcanic zone new zealand the taupo volcanic zone tvz the predominant active volcano tectonic structure within the new zealand sub continent marks the zone of quaternary back arc spreading and calc alkaline volcanism associated with the convergence of the pacific and australian plates at the hikurangi plate boundary margin north island new zealand new bathymetric shallow seismic reflection magnetic anomaly and gloria data presented here accurately define for the first time the extent structure and tectonism of the poorly known offshore portion of the tvz these data show that nearly half of the entire ca 40 km wide tvz lies offshore extending northeast for some 150 km seaward to 36 45 s the southeastern and northwestern boundaries of the offshore tvz are significant tectonic and bathymetric features which comprise inward facing normal fault zone the white island and tauranga fault zones respectively three essentially parallel tectono morphological units are identified along the length of the offshore tvz they comprise from southeast to northwest a frontal non volcanic graben a volcanic ridge and a volcanic back arc graben the spatial position of these units with respect to the hikurangi subduction margin is not a simple arc and back arc relationship tectonism within the offshore tvz although pervasive increases from northwest to southeast so that the area of highest extension and subsidence of the non volcanic graben occurs in front of the volcanic ridge geophysical data also suggest the possible tectonic ablation of blocks of the forearc hinterland into the offshore tvz along its southeastern margin the southern havre trough and northern tvz are offset sinistrally by 45 50 km they overlap by 40 km and differ in orientation by ca 7 dextral displacement between these two extensional regimes is accomodated by a series of dextrally oblique and en echelon bookshelf faults the orientation of extensional structures within the offshore tvz is also dextrally oblique by 10 15 to the regional 030 trend of the bounding faults and agree with axes of maximum extension determined elsewhere from geodetic and seismological data

thermal tides in the atmosphere of venus comparison of model results with observations a linearized primitive equation lpe model is developed to study thermal tides in the atmosphere of venus the lpe model describes diurnal and semidiurnal oscillations of a cyclostrophically balanced atmosphere in which zonal velocity varies with altitude and latitude the numerical algorithm follows staniforth and daley the solar thermal forcing is increased algebraically in time to separate the forced tidal response from free atmospheric oscillations parameters of the basic state and forcing agree with pioneer venus observations results of the model are compared with the solar fixed component of brightness temperature variations measured by taylor et al and elson using data from the pioneer venus orbiter infrared radiometer oir the comparison is made by convolving the computed model radiances with the weighting functions of the oir channels agreement between lpe model results and oir observations is excellent two interesting features of the oir data are accounted for namely the slow variation of phase with altitude and the dominance of the semidiurnal oscillation over the diurnal oscillation success of the lpe model opens the way for calculating tidal transports of heat and momentum and assessing the role of tides in maintaining the venus super rotation

zonal winds in the middle atmosphere of venus from pioneer venus radio occultation data abstract pioneer venus radio occultation data for four seasons between december 1978 and october 1981 are used to construct meridional cross sections of temperature and zonal wind velocity for the middle atmosphere of venus in the altitude range of 40 80 km and in the latitude range of 1 5 85 wind speeds are derived assuming cyclostrophic balance the wind field contains as many as three jets first a prominent one above the clouds situated between 50 and 55 latitude with a maximum speed of 140 m s 1 a second with a speed of 95 m s 1 centered at 70 and at 60 km altitude and a possible third jet at 15 and 65 km altitude with a speed of 100 m s 1 the notable midlatitude jet is associated with the cold polar collar wind speeds above 70 km generally decrease with height because of the warm pole at these levels however within the jet the speed is 100 m s 1 at 83 km the jets may be barotropically unstable and inertial instability may occur above the clouds on the equatorial side of the main

assessing the long term variability of venus winds at cloud level from virtis venus express abstract the venus express vex mission has been in orbit to venus for more than 4 years now the visible and infrared thermal imaging spectrometer virtis instrument onboard vex observes venus in two channels visible and infrared obtaining spectra and multi wavelength images of the planet that can be used to sample the atmosphere at different altitudes day side images in the ultraviolet range 380 nm are used to study the dynamics of the upper cloud at 66 72 km while night side images in the near infrared 1 74 m map the opacity of the lower cloud deck at 44 48 km here we present a long term analysis of the global atmospheric dynamics at these levels using a large selection of orbits from the virtis m dataset covering 860 earth days that extends our previous work sanchez lavega a et al 2008 geophys res lett 35 l13204 and allows studying the variability of the global circulation at the two altitude levels the atmospheric superrotation is evident with equatorial to mid latitudes westward velocities of 100 and 60 m s 1 in the upper and lower cloud layers these zonal velocities are almost constant in latitude from the equator to 50 s from 50 s to 90 s the zonal winds at both cloud layers decrease steadily to zero at the pole individual cloud tracked winds have errors of 3 10 m s 1 with a mean of 5 m s 1 and the standard deviations for a given latitude of our zonal and meridional winds are 9 m s 1 the zonal winds in the upper cloud change with the local time in a way that can be interpreted in terms of a solar tide the zonal winds in the lower cloud are stable at mid latitudes to the tropics and present variability at subpolar latitudes apparently linked to the activity of the south polar vortex while the upper cloud presents a net meridional motion consistent with the upper branch of a hadley cell with peak velocity v 10 m s 1 at 50 s the lower cloud meridional motions are less organized with some cloud features moving with intense northwards and southwards motions up to v 15 m s 1 but on average with almost null global meridional motions at all latitudes we also examine the long term behavior of the winds at these two vertical layers by comparing our extended wind tracked data with results from previous missions

developing sub 5 m lidar dems for forested sections of the alpine and hope faults south island new zealand implications for structural interpretations abstract kilometre wide airborne light detection and ranging lidar surveys were collected along portions of the alpine and hope faults in new zealand to assess the potential for generating sub 5 m bare earth digital elevation models dems from ground return data in areas of dense rainforest bush cover as an aid to mapping these faults the 34 km long franz whataroa lidar survey was flown along the densely vegetated central most portion of the transpressive alpine fault six closely spaced flight lines 200 m apart yielded survey coverage with double overlap of swath collection which was considered necessary due to the low density of ground returns 0 16 m 2 or a point every 6 m2 under mature west coast podocarp broadleaf rainforest this average point spacing 2 5 m allowed for the generation of a robust high quality 3 m bare earth dem the dem confirmed the zigzagged form of the surface trace of the alpine fault in this area originally recognised by norris and cooper 1995 norris and cooper 1997 and highlights that the surface strike variations are more variant than previously mapped the 29 km long hurunui hope lidar survey was flown east of the main divide of the southern alps along the dextral slip hope fault where the terrain is characterised by lower rainfall and more open beech forest flight line spacings of 275 m were used to generate a dem from the ground return data the average ground return values under beech forest were 0 27 m 2 and yielded an estimated cell size suitable for a 2 m dem in both cases the lidar revealed unprecedented views of the surface geomorphology of these active faults lessons learned from our survey methodologies can be employed to plan cost effective high gain airborne surveys to yield bare earth dems underneath vegetated terrain and multi storeyed canopies from densely forested environments across new zealand and worldwide

an extending island arc the case of kamchatka abstract we report a first estimate of the extension rate of the onshore kamchatka island arc it central wider part this average rate is 17 3 mm yr over mid late quaternary time the extension is absorbed by slip on major normal active faults of central kamchatka and graben producing faulting in its volcanic belt probable extension of the underwater portion of the arc its rate remaining unknown may add up to the total value the onshore extension rate established by remote fault scarp measurements on dems resembles the numerical modelling estimate of schellart et al 2007 suggesting that the primary driving force responsible for the extension at kamchatka is slab and trench retreat

southern hemispheric westerlies control sedimentary processes of laguna azul south eastern patagonia argentina multiproxy investigations of lacustrine sediments from laguna azul 52 s document multi millennial holocene influences of southern hemispheric westerlies shw on the hydroclimatic variability of

fault slip accumulation in an active rift over thousands to millions of years and the importance of paleoearthquake sampling abstract the catastrophic earthquakes that recently september 4th 2010 and february 22nd 2011 hit christchurch new zealand show that active faults capable of generating large magnitude earthquakes can be hidden beneath the earth s surface in this article we combine near surface paleoseismic data with deep 1 ma timescales in the taranaki rift new zealand our analysis shows that the integration of different timescale datasets provides a basis for identifying active faults not observed at the ground surface estimating maximum fault rupture lengths inferring maximum short term displacement rates and improving earthquake hazard assessment we find that fault displacement rates become increasingly irregular both faster and slower on shorter timescales leading to incomplete sampling of the active fault population surface traces have been recognised for

fluid controlled faulting process in the asal rift djibouti from 8 yr of radar interferometry observations the deformation in the asal rift djibouti is characterized by magmatic inflation diking distributed extension fissure opening and normal faulting an 8 yr time line of surface displacement maps covering the rift constructed using radar interferometry data acquired by the canadian satellite radarsat between 1997 and 2005 reveals the aseismic behavior of faults and its relation with bursts of microseismicity the observed ground movements show the asymmetric subsidence of the inner floor of the rift with respect to the bordering shoulders accommodated by slip on three of the main active faults fault slip occurs both as steady creep and during sudden slip events accompanied by an increase in the seismicity rate around the slipping fault and the fieale volcanic center slip distribution along fault strike shows triangular sections a pattern not explained by simple elastic dislocation theory these observations suggest that the asal rift faults are in a critical failure state and respond instantly to small pressure changes in fluid filled fractures connected to the faults reducing the effective normal stress on their locked section at depth

normal fault growth and linkage in the whakatane graben new zealand during the last 1 3 myr determination of fault growth rates and fault network evolution at time scales from 104 106 years has been hampered by a lack of a well constrained stratigraphic succession that provides a high fidelity record of fault development over these time periods here we show how seismic reflection data of different spatial resolutions can be used to constrain the linkage history and displacement rate variations of a single major fault we present data collected in the offshore whakatane graben bay of plenty new zealand where intense normal faulting occurs as a result of active back extension the focus of our study is the rangitaiki fault a linked segmented normal fault which is the dominant active structure in the graben the total linked fault length is c 20 km long and has a displacement of up to 830 130 m in the top 1 5 km of sediments the fault has been actively growing for the last 1 34 0 51 ma and has developed from isolated fault segments to a fully linked fault system initially the dominant process of fault growth was tip propagation with an average and maximum displacement rates of 0 52 0 18 mm yr 1 and 0 72 0 23 mm yr 1 respectively interaction and linkage became more significant as the fault segments grew towards each other resulting in the fault network becoming fully linked between 300 and 18 ka following fault segment linkages the average displacement rate of the fault network increased by almost three fold to 1 41 0 31 mm yr 1 while the maximum displacement rate increased to 2 72 0 61 mm yr 1 this is the first time that the growth rate of unlinked fault segments has been resolved and has been shown to be slower than in the subsequent linked fault system

a 667 year record of coseismic and interseismic coulomb stress changes in central italy reveals the role of fault interaction in controlling irregular earthquake recurrence intervals current studies of fault interaction lack sufficiently long earthquake records and measurements of fault slip rates over multiple seismic cycles to fully investigate the effects of interseismic loading and co seismic stress changes on the surrounding fault network we model elastic interactions between 97 faults from 30 earthquakes since 1349 ad in central italy to investigate the relative importance of co seismic stress changes versus interseismic stress accumulation for earthquake occurrence and fault interaction this region has an exceptionally long 667 year record of historical earthquakes and detailed constraints on the locations and slip rates of its active normal faults of 21 earthquakes since 1654 20 events occurred on faults where combined co seismic and interseismic loading stresses were positive even though 20 of all faults are in stress shadows at any one time furthermore the coulomb stress on the faults that experience earthquakes is statistically different from a random sequence of earthquakes in the region we show how co seismic coulomb stress changes can alter earthquake inter event times by c 103 years and fault length controls the intensity of this effect static coulomb stress changes cause greater inter event perturbations on shorter faults in areas characterized by lower strain or slip rates the exceptional duration and number of earthquakes we model enable us to demonstrate the importance of combining long earthquake records with detailed knowledge of fault geometries slip rates and kinematics to understand the impact of stress changes in complex networks of active faults

heterogeneity of structure and stress in the rotokawa geothermal field new zealand geometric characterization of a geothermal reservoir s structures and their relation to stress field orientation is vital for resource development subsurface structure and stress field orientations of the rotokawa geothermal field new zealand have been studied for the first time using observations obtained from analysis of three acoustic borehole televiewer logs while an overall ne sw fracture strike exists heterogeneity in fracture dip orientation is evident dominant dip direction changes from well to well due to proximity to variously oriented graben bounding faults fracture orientation heterogeneity also occurs within individual wells where fractures clusters within certain depth intervals have antithetic dip directions to the well s dominant fracture dip direction these patterns are consistent with expected antithetic faulting in extensional environments a general shmax orientation of ne sw is determined from induced features on borehole walls however numerous localized azimuthal variations from this trend are evident constituting stress field orientation heterogeneity these variations are attributed to slip on fracture planes evidenced by changes in the azimuth of drilling induced tensile fractures either side of a natural fracture correlation of observed fracture properties and patterns to well permeability indicators reveal that fractures play a role in fluid flow in the rotokawa geothermal reservoir permeable zones commonly contain wide aperture fractures and high fracture densities which have a dominant ne sw strike orientation and nw dip direction studies of this kind which show strong interdependency of structure and stress field properties are essential to understand fluid flow in geothermal reservoirs where structural permeability dominates

fault displacement rates on a range of timescales abstract displacements on tectonic faults primarily accrue during earthquakes at rates that vary through time to examine the processes that underlie the temporal changes in fault displacement rates we analyse displacements and displacement rates for time periods from the present to 5 10 20 300 500 1000 and 5000 kyr for 261 active reverse or normal faults from a worldwide dataset displacement rates depart from million year average rates by up to three orders of magnitude with the size of these departures inversely related to the duration of the sample period and to fault length short term 20 kyr displacement rates generally span a greater range on small faults than large a feature which suggests more variable growth on smaller faults simple earthquake slip modeling shows that variations in displacement rates require changes in both recurrence interval and slip per event and do not support the characteristic slip earthquake model as long as fault system strain rates are uniform displacement rates generally become constant over time periods between 20 and 300 kyr with the length of time required to reach stability being inversely related to the regional basin wide strain rates stable long term displacement rates and fluctuations in earthquake recurrence intervals and slip arise in part due to fault interactions

ages of prehistoric earthquakes revealed by cosmogenic chlorine 36 in a bedrock fault scarp at hebgen lake cosmogenic chlorine 36 reveals dates of the multiple prehistoric earthquakes that have produced a scarp on the hebgen lake fault apparent chlorine 36 ages are stratigraphically correct follow a predicted theoretical pattern and produce geologically reasonable model ages of 24 20 7 0 2 6 1 7 and 0 4 thousand years ago this result demonstrates the feasibility of using cosmogenic chlorine 36 to extract paleoearthquake records from bedrock fault scarps

a 48 kyr long slip rate history for the jordan valley segment of the dead sea fault abstract we investigate the late quaternary active deformation along the jordan valley segment of the left lateral dead sea fault and provide new insights on the behaviour of major continental faults the 110 km long fault segment shows systematic offsets of drainage systems surveyed at three sites along its southern section the isotopic dating of six paleoclimatic events yields a precise chronology for the onset of six generations of gully incisions at 47 5 ka bp 37 5 ka bp 13 ka bp 9 ka bp 7 ka bp and 5 ka bp additionally detailed mapping and reconstructions provide cumulative displacements for 20 dated incisions along the fault trace the individual amounts of cumulative slip consistently fall into six distinct classes this yields i an average constant slip rate of 4 7 to 5 1 mm yr for the last 47 5 kyr and ii a variable slip rate ranging from 3 5 mm yr to 11 mm yr over 2 kyr to 24 kyr long intervals taking into account that the last large earthquake occurred in ad 1033 we infer 3 5 to 5 m of present day slip deficit which corresponds to a mw 7 4 earthquake along the jordan valley fault segment the timing of cumulative offsets reveals slip rate variations critical to our understanding of the slip deficit and seismic cycle along major continental faults

the importance of microearthquakes in crustal extension of an active rift a case study from new zealand received 24 august 2012 revised 29 november 2012 accepted 19 december 2012 1 the amount of extension accommodated in active rifts by earthquakes that do not rupture the ground surface e g mw 5 5 is often poorly constrained the matata earthquake sequence mes a high quality dataset of 2563 relocated microearthquakes 1 mw 4 7 that ruptured the taupo rift in new zealand over a period of 49 months has been used to quantify the proportion of extension produced by small to moderate sized earthquakes analysis shows that the extension rate across the rift due to the mes is 2 4 0 7 mm yr at 1s standard deviation an average extension rate for small to moderate magnitude earthquakes which also prevailed during the preceding 28 years 1977 2004 and represents up to 30 of the total contemporary deformation recorded across the north taupo rift by gps 15 5 mm yr the bulk of the mes 94 occurred at depths of 1 5 to 6 5 km and may not be observed in geological datasets e g as displacements of the ground or near surface horizons small scale faulting associated with microseismicity may thus record strains not measured by geological datasets and constitute an important component of the 3 10 mm yr disparity between geological and gps rates of extension across the taupo rift

localized vs distributed deformation associated with the linkage history of an active normal fault whakatane graben new zealand abstract the deformation associated with an active normal fault is investigated at a high temporal resolution c 10 4 yr the rangitaiki fault whakatane graben new zealand and its adjacent faults accommodated an overall extension of 0 83 oriented at n324 e over the past 17 kyr this is consistent along strike but the pattern of faulting that accommodates this strain defines two different spatial domains to the sw one domain is characterized by a few large faults with 80 of strain localized onto geometrically and kinematically linked segments of the main fault this produces marked heterogeneity in the spatial distribution of strain across the graben in contrast to the ne a domain of distributed faulting is characterized by numerous small faults contributing to the overall deformation with only 35 of strain localized onto the rangitaiki fault the transition from distributed to localized deformation is attributed to an increase in linkage maturity of the rangitaiki fault progressive strain localization has been ongoing within the network over the last 17 kyr with localization of fault activity increasing by 12 indicating this process occurs over kyr time periods that only reflect a few earthquake events

interdependence of fault displacement rates and paleoearthquakes in an active rift paleoearthquakes at earth s surface often generate faults with variable displacement rates over short time intervals e g 18 k y the nature and origin of these variations and the extent to which they result from systematic and therefore predictable earthquake processes is unresolved we examine the processes underlying fluctuations in displacement rates by charting the accumulation of displacement over the last 60 k y on 25 normal fault traces distributed across the taupo rift new zealand displacement rates become more stable with increasing fault size and are uniform when aggregated across the entire rift the increased stability of fault displacement rates at greater spatial scales suggests that each fault is a component of a kinematically coherent system in which all faults interact and their earthquake histories are interdependent fault interdependencies generate short term complex 18 k y fluctuations in the timing and magnitude of earthquakes but also ultimately result in the stability of displacement rates on million year time scales

improved automatic estimation of winds at the cloud top of venus using superposition of cross correlation surfaces abstract accurate wind observation is a key to study atmospheric dynamics a new automated cloud tracking method for the dayside of venus is proposed and evaluated by using the ultraviolet images obtained by the venus monitoring camera onboard the venus express orbiter it uses multiple images obtained successively over a few hours cross correlations are computed from the pair combinations of the images and are superposed to identify cloud advection it is shown that the superposition improves the accuracy of velocity estimation and significantly reduces false pattern matches that cause large errors two methods to evaluate the accuracy of each of the obtained cloud motion vectors are proposed one relies on the confidence bounds of cross correlation with consideration of anisotropic cloud morphology the other relies on the comparison of two independent estimations obtained by separating the successive images into two groups the two evaluations can be combined to screen the results it is shown that the accuracy of the screened vectors are very high to the equatorward of 30 degree while it is relatively low at higher latitudes analysis of them supports the previously reported existence of day to day large scale variability at the cloud deck of venus and it further suggests smaller scale features the product of this study is expected to advance the dynamics of venusian atmosphere

magnitude versus faults surface parameters quantitative relationships from the aegean region historical and seismotectonic data from the broader aegean region have been collected and all possible information relative to ground deformation associated to earthquakes that hit the area have been re evaluated all events associated to co seismic surface faulting have been selected and further investigated while geomorphologic and geological criteria have been used to recognise and characterise the seismogenic faults associated to these morphogenic earthquakes sensu bull inqua 16 1993 24 in particular in order to perform seismic hazard analyses we compiled a list of all earthquakes where the surface rupture length srl the maximum vertical displacement mvd or the average displacement ad is available we thus obtained reliable values of these source parameters for 36 earthquakes of which 26 occurred during the 20th century 6 in the 19th century and the 3 remaining earlier magnitude versus srl and mvd has been compiled for estimating empirical relationships the calculated regression equations are ms 0 90 log srl 5 48 and ms 0 5 9log mvd 6 75 showing good correlation coefficients equal to 0 84 and 0 82 respectively co seismic fault rupture lengths and especially maximum displacements in the aegean region have systematically lower values than the same parameters worldwide but are similar to those of the eastern mediterranean middle east region the envelopes of our diagrams are also calculated and discussed for estimating the worst case scenario furthermore for all investigated seismogenic structures based on several geological criteria we measured the geological fault length gfl which is the total length of the neotectonic faults showing cumulative recent activity we then compared srl with gfl and their ratio shows a clear bimodal distribution with a major peak at 0 8 1 0 indicating that about 50 of the investigated earthquakes ruptured almost the entire fault length while a second peak around the value of 0 5 is clearly related to a segmentation process of longer neotectonic structures further implications of this distribution are also discussed eventually from the distribution of gfl versus magnitude we also infer an important geological threshold for the occurrence of morphogenic earthquakes at about 5 5 degrees

high resolution record of displacement accumulation on an active normal fault implications for models of slip accumulation during repeated earthquakes the spatial and temporal accumulation of slip from multiple earthquake cycles on active faults is poorly understood here we describe a methodology that can determine the time period of observation necessary to reliably constrain fault behaviour using a high resolution longtimescale the last 17 kyr fault displacement dataset over the rangitaiki fault whakatane graben new zealand the fault linked at ca 300 ka bp and analysis of time periods within the last 17 kyr gives insight into steady state behaviour for time intervals as short as ca 2 kyr the maximum displacement rate observed on the rangitaiki fault is 3 6g1 1 mm yr k1 measured over 17 kyr displacement profiles of the last 9 ka of fault movement are similar to profiles showing the last 300 ka offault movement in contrast profiles determined for short time intervals 2 3 kyr are highly irregular and show points of zero displacement on the larger segments this indicates temporal and spatial variability in incremental displacement associated with surface rupturing slip events there is spatial variability in slip rates along fault segments with minima at locations of fault interaction or where fault linkage has occurred in the past this evidence suggests that some earthquakes appear to have been confined to specific segments whereas larger composite ruptures have involved the entire fault the short term variability in fault behaviour suggests that fault activity rates inferred from geodetic surveys or surface ruptures from a single earthquake may not adequately represent the longer term activity nor reflect its future behaviour different magnitude events may occur along the same fault segment with asperities preventing whole segment rupture for smaller magnitude events q 2006 elsevier ltd all rights reserved

fault controls on the geometry and location of the okataina caldera taupo volcanic zone new zealand abstract okataina caldera is located within the taupo rift and formed due to collapse following eruptions at 325 and 61 ka gravity seismic reflection topographic and geological data indicate that active rift faults pass into the caldera and have influenced its location and geometry the caldera has a minimum gravity anomaly of 50 mgal is elongate north south with an inferred minimum depth to caldera floor of 3 0 5 km at the rift axis and occupies a 10 km hard linked left step in the rift the principal rift faults 55 75 dip define the location and geometry of the northwest and southeast caldera margins and locally accommodate piecemeal collapse segments of the east and west margins of the caldera margin are near vertical 70 90 dip trend north south and are inferred to be faults formed by the reactivation of a pervasive mesozoic basement fabric i e faults and or lithological contacts the fault sets which define the caldera geometry predate it while the step in the rift across the okataina volcanic centre ovc is at least as old as the caldera within the ovc displacement on rift faults induced by gravitational caldera collapse at 61 ka exceeds tectonic displacement since this time by at least a factor of two collapse along pre existing rift faults and in particular mesozoic basement fabric are important for caldera formation elsewhere in the taupo volcanic zone

tectonic controls on taupo volcanic zone geothermal expression insights from te mihi wairakei geothermal field information on structure stress and their interrelationship is essential for understanding structurally controlled geothermal permeability active fault mapping borehole image analysis and well testing in the te mihi geothermal area new zealand allows us to refine structural and fluid flow architecture of this resource the te mihi area is structurally complex comprising a set of nw dipping master faults containing pervasive se dipping antithetic and splay structures in their hanging walls these faults are also intersected by e w striking faults a localized n s striking structural trend is also observed at te mihi in consideration with global navigation satellite system velocity vectors both active ne sw and e w striking faults create biaxial extension at te mihi though the observed ne sw shmax direction suggests that contemporary extension is nw se dominated stress field perturbations coincide with structural complexities like fault splays and intersections and or proximity to recently active e w and ne sw striking structures borehole fluid flow at te mihi is concentrated at nw dipping master fault intersections travel time fractures on acoustic image logs halo fractures on resistivity image logs ne sw and e w striking fractures intervals of high fracture density and spatial concentrations of wide aperture fractures and recently active ne sw and e w striking fractures this study suggests te mihi geothermal expression results from biaxial extension evident from active structural trend intersections and the predominance of ne sw and e w striking structures within permeable well zones biaxial extension is therefore an important control on crustal fluid flow within the taupo volcanic zone and thus geothermal resource delineation

maintenance of strong rotational winds in venus middle atmosphere by thermal tides the cloud level atmosphere of venus takes little more than 4 days to complete one rotation whereas the solid planet below has a 243 day period computer simulations of the circulation of the venus middle atmosphere between 40 and 85 kilometers as driven by solar radiation absorbed in the clouds reproduce i the observed cloud level rotation rate ii strong vertical shears above and below the cloud tops and iii midlatitude jets and strong poleward flow on the day side simulated circulations converge to yield nearly the same zonal winds when initialized with both stronger or weaker rotation rates these results support the hypothesis that the observed cloud top rotation rate is maintained by statistical balance between fluxes of momentum by thermal tides and momentum advection by mean meridional circulation

high resolution topography for understanding earth surface processes opportunities and challenges abstract in the last decade a range of new remote sensing techniques has led to a dramatic increase in terrain information providing new opportunities for a better understanding of earth surface processes based on geomorphic signatures technologies such as airborne and terrestrial lidar light detection and ranging to obtain high resolution topography have opened avenues for the analysis of landslides hillslope and channellization processes river morphology active tectonics volcanic landforms and anthropogenic signatures on topography this review provides an overview of the recent flourishing literature on high resolution topographic analyses underlining their opportunities and critical issues such as their limitations the goal is to provide answers to questions such as what kind of processes can be analyzed through high resolution topographic data and how to do it the review focuses on two different environments natural and engineered landscapes in both contexts high resolution topography offers opportunities to better understand geomorphic processes from topographic signatures particular attention is given to engineered landscapes in which the direct anthropic alteration of processes is significant the last part of the review discusses future challenges

motion and rigidity of the pacific plate and implications for plate boundary deformation 1 using up to 11 years of data from a global network of global positioning system gps stations including 12 stations well distributed across the pacific plate we derive present day euler vectors for the pacific plate more precisely than has previously been possible from space geodetic data after rejecting on statistical grounds the velocity of one station on each of the pacific and north american plates we find that the quality of fit of the horizontal velocities of 11 pacific plate pa stations to the best fitting pa euler vector is similar to the fit of 11 australian plate au velocities to the au euler vector and 20 better than the fit of nine north american plate na velocities to the na euler vector the velocities of stations on the pacific and australian plates each fit a rigid plate model with an rms residual of 0 4 mm yr while the north american velocities fit a rigid plate model with an rms velocity of 0 6 mm yr our best fitting pa au relative euler vector is located 170 km southeast of the nuvel 1a pole but is not significantly different at the 95 confidence level it is also close 70 km in position and 3 in rate to a pole derived from transform faults identified from satellite altimetry suggesting that the vector has not changed significantly over the past 3 myr our relative euler vector is also consistent with all known geological and geodetic evidence concerning the au pa plate boundary through new zealand the gps sites offshore of southern california are presently moving 4 5 1 mm yr relative to predicted pacific velocity with their residual velocities in approximately the opposite direction to pa na relative motion likewise the easternmost sites in south island new zealand are moving 3 1 mm yr relative to predicted pacific velocity with the residuals in approximately the opposite direction to pa au relative motion these velocity residuals are in the same sense as predicted by elastic strain accumulation on known plate boundary faults but are of a significantly higher magnitude in both southern california and new zealand implying that the plate boundary zones in both regions are wider than previously believed index terms 1206 geodesy and gravity crustal movements interplate 8155 1208 geodesy and gravity crustal movements intraplate 8110 1243 geodesy and gravity space geodetic surveys 8158 tectonophysics evolution of the earth plate motions present and recent 3040 8159 tectonophysics evolution of the earth rheology crust and lithosphere keywords pacific plate motion plate rigidity plate boundary deformation

patterns of tectonic fault interactions captured through geostatistical analysis of microearthquakes 1 historical earthquakes are often strongly clustered in space and time this clustering has been attributed to static stress triggering associated with tectonic fault interactions and or to fluid migration discrimination between these two models requires detailed information on the timing location and size of earthquakes the matata earthquake sequence in the taupo rift new zealand provides a unique opportunity to chart spatial and temporal patterns of earthquakes along individual faults and their relations to other faults in the system over timescales of days to years this is possible because there are 2563 accurately relocated within 5 5 earthquakes that occur over thousand year timescales e g 60 kyr

gravitational signatures of atmospheric thermal tides on venus abstract thermal tides in the atmosphere of venus transport a considerable amount of mass on a wide range of spatial and temporal scales we use simulated values of the surface atmospheric pressure distribution to estimate the time varying gravitational potential exterior to venus the expected amplitudes of gravitational signatures of thermal tides are below the errors from existing magellan mission doppler data and have not yet been detected however they are large enough that we expect them to be well resolved by any of several measurement configurations for future venus gravity missions

global scale winds at the venus cloud top inferred from cloud streak orientations abstract the orientations of the small cloud streaks that are always found at mid latitudes in ultraviolet images of the venus cloud top provide a means for characterizing the global scale circulation including the wind field on the night side of venus assuming that small clouds act as passive tracers of the cloud top wind field the orientation of cloud streaks is determined by the wind shear that the cloud has recently experienced the typical deformation time for small clouds is about 50 hr or one half of a cloud top rotation so clouds viewed on the sunlit half of venus show the influence of daytime and nighttime winds by recording the orientations of cloud streaks and their variation with local solar time we for the first time use cloud orientation information to place a constraint on the amplitudes of the hadley circulation and solar thermal tides at the cloud top level a large solar thermal tide with a cloud top meridional wind amplitude at 45 latitude of between 5 5 10 5 m sec 1 is found to be necessary to account for the observed variation with local solar time of cloud streak orientations maximum poleward tidal winds occur in the early afternoon the cloud top hadley circulation is estimated to have an amplitude at 45 latitude of between 3 5 and 8 5 m s 1 this means the hadley circulation may not be the dominant contributor to cloud top meridional velocities and that equatorward meridional velocities may exist over a portion of the night side at the venus cloud top

long term earthquake clustering a 50 000 year paleoseismic record in the dead sea graben the temporal distribution of earthquakes in the dead sea graben is studied through a 50 000 year paleoseismic record recovered in laminated sediments of the late pleistocene lake lisan paleo dead sea the lisan represents more than 10 times the 4000 years of historical earthquake records it is the longest and most complete paleoseismic record along the dead sea transform and possibly the longest continuous record on earth it includes unique exposures of seismite beds earthquake induced structures associated with slip events on syndepositional faults the seismites are layers consisting of mixtures of fragmented and pulverized laminae the places where the seismites abut syndepositional faults are interpreted as evidence for their formation at the sediment water interface during slip events on these faults thicker sediment accumulation above the seismites in the downthrown blocks indicates that a seismite formed at the water sediment interface on both sides of the fault scarps modern analogs and the association with surface ruptures suggest that each seismite formed during a m l 5 5 earthquake the 230 th 234 u ages of a columnar section obtained by thermal ionization mass spectrometry give a mean recurrence time of 1600 years of m l 5 5 earthquakes in the dead sea graben the earthquakes cluster in 10 000 year periods separated by quiet periods of similar length this distribution implies that a long term behavior of the dead sea transform should be represented by a mean recurrence of at least 20 000 year record this observation has ramifications for seismic hazard assessment based on shorter records

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

slip history of the magnola fault apennines central italy from 36cl surface exposure dating evidence for strong earthquakes over the holocene to better understand the mechanics of deformation in the mediterranean and the role that the convergence between africa and europe plays it is necessary to know the deformation field at different time scales here we use in situ 36 cl surface exposure dating of exposed bedrock fault scarps to determine earthquake time slip histories and to quantify slip rates over the last several thousand years this information allows us to delineate the seismic history of normal faulting within the mediterranean area over that time period we have studied the limestone scarp produced by the magnola fault in the central apennines italy the magnola fault in the fucino area is an active 15 km long normal fault striking wnw and dipping ssw the range front morphology characterised by steep triangular facets separated by v shaped valleys and wine glass canyons suggests that the magnola fault has been active for at least the last several hundred thousand years at the base of the facets the fault cuts limestone bedrock to produce a well preserved normal fault scarp 10 to 12 m high the distribution of 36 cl concentration versus the height along that scarp is best explained by a minimum of five and a maximum of seven successive earthquake exhumations with slips varying between 1 5 and 3 m an age of 5 ka at the base of the scarp and of 12 ka at the top yields a slip rate of 0 8 mm year the absence of any event on this fault during the last 5000 years suggests either that a future event is imminent on the magnola fault or that the fault has entered a quiescent period with

fluvial responses to volcanism resedimentation of the 1800a taupo ignimbrite eruption in the rangitaiki river catchment north island new zealand abstract the potential for the generation of dangerous and damaging lahars and floods in response to the eruption of voluminous pyroclastic debris has become increasingly appreciated in recent years the style and tempo of this response varies both between eruptions and between individual catchments impacted by a single eruption so that an understanding of the factors controlling this variation is necessary for precise hazard assessment the 1800a taupo eruption from the taupo volcanic centre in the central north island of new zealand devastated an area of 20 000 km 2 during eruption of a climactic ignimbrite impacting the headwaters of all major rivers draining radially from this region the rangitaiki river the subject of this paper differs from other catchments in that the taupo ignimbrite buried an essentially flat land surface inherited from a suite of welded ignimbrite sheets erupted between 320 340 and 230 ka the middle reaches of the catchment are characterised by narrow steep gorges alternating with low gradient basins developed in tectonic half grabens initially remobilisation of pyroclastic material in the headwaters was dominated by hyperconcentrated sheet flows resulting in shallow reworking in higher gradient areas reintegration of drainage networks was achieved by incision of deep channels and gullies assisted by breakouts from ephemeral lakelets developed in ignimbrite dammed depressions braided and later meandering streams superseded this pattern as rill and gully systems stabilised and sediment yields fell leading to a decline in drainage density gorge reaches acted as efficient conduits for remobilised material while the basins acted as local depocentres for the temporary storage of volcaniclastic sediments mediating the transfer of pyroclastic debris to the bay of plenty coast 100 km to the north reworking and resedimentation of pyroclastic debris began immediately after the eruption peaking early and then rapidly declining so that most geomorphic adjustments occurred within one or two decades of the initial disturbance

venus topography and kilometer scale slopes during the first 8 months of the magellan mission the radar altimeter has made some three million measurements of the surface of venus covering the latitude range from 85 n to 80 s methods involving range correlation doppler filtering multi burst summation and range migration are used to focus the observations and to achieve high surface resolution results are presented as maps of the global distribution of topography meter scale roughness and power reflection coefficient the results are similar to those reported in previous experiments surface heights exhibit a unimodal distribution with more than 80 of the surface lying within 1 km of the 6051 84 km mean radius but the higher resolution of the magellan altimeter has disclosed several surprisingly steep features e g the southwest face of the maxwell montes the southern face of the danu montes and the chasmata to the east of thetis regio where average kilometer scale slopes of greater than 30 are not uncommon this conclusion is corroborated by close inspection of synthetic aperture radar imagery

atmospheric mountain wave generation on venus and its influence on the solid planet s rotation rate the akatsuki spacecraft observed a 10 000 km long meridional structure at the top of the cloud deck of venus that appeared stationary with respect to the surface and was interpreted as a gravity wave additionally over four venus solar days of observations other such waves were observed to appear in the afternoon over equatorial highland regions this indicates a direct influence of the solid planet on the whole venusian atmosphere despite dissimilar rotation rates of 243 and 4 days respectively how such gravity waves might be generated on venus is not understood here we use general circulation model simulations of the venusian atmosphere to show that the observations are consistent with stationary gravity waves over topographic highs or mountain waves that are generated in the afternoon in equatorial regions by the diurnal cycle of near surface atmospheric stability we find that these mountain waves substantially contribute to the total atmospheric torque that acts on the planet s surface we estimate that mountain waves along with the thermal tide and baroclinic waves can produce a change in the rotation rate of the solid body of about 2 minutes per solar day this interplay between the solid planet and atmosphere may explain some of the difference in rotation rates equivalent to a change in the length of day of about 7 minutes measured by spacecraft over the past 40 years

assessing debris flows using lidar differencing 18 may 2005 matata event new zealand the town of matata in the eastern bay of plenty new zealand experienced an extreme rainfall event on the 18 may 2005 this event triggered widespread landslips and large debris flows in the awatarariki and waitepuru catchments behind matata the light detection and ranging technology lidar data sets flown prior to and following this event have been differenced and used in conjunction with a detailed field study to identify the distribution of debris and major sediment pathways which from the awatarariki catchment transported at least 350 000 50 000 m3 of debris debris flows were initially confined to stream valleys and controlled by the density and hydraulic thrust of the currents before emerging onto the awatarariki debris fan where a complex system of unconfined sediment pathways developed here large boulders clasts logs and entire homes were deposited as the flows decelerated downstream from the debris fan the pre existing coastal foredune topography played a significant role in deflecting the more dilute currents that in filled lagoonal swale systems in both directions the differenced lidar data have revealed several sectors characterised by significant variation in clast size thickness and volume of debris as well as areas where post debris flow cleanup and grading operations have resulted in man made levees sediment dumps scoured channels and substantial graded areas the application of differenced lidar data to a debris flow event demonstrates the techniques potential as a precise and powerful tool for hazard mapping and assessment

structure of the venus neutral atmosphere as observed by the radio science experiment vera on venus express 1 the european space agency venus express radio science experiment vera obtained 118 radio occultation measurements of the venusian atmosphere between july 2006 and june 2007 southern latitudes are uniformly sampled measurements in the northern hemisphere are concentrated near the pole radial profiles of neutral number density derived from the occultations cover the altitude range 40 90 km which are converted to profiles of temperature t and pressure p versus height h profiles of static stability are found to be latitude dependent and nearly adiabatic in the middle cloud region below the clouds the stability decreases at high latitudes at an altitude of 65 km the vera t p h profiles generally lie between the venus international reference atmosphere vira and vira 2 models the retrieved temperatures at any given pressure level typically are within 5 k of those derived from the pioneer venus orbiter radio occultation experiments a large equator to pole temperature contrast of 30 k is found at the 1 bar 1000 hpa level the vera observations reveal a distinct cold collar region in the southern hemisphere complementing that in the north at the latitudes of the cold collars the tropopause altitude increases relative to higher and lower latitudes by 7 km while the temperature drops roughly 60 k the observations indicate the existence of a wave number 2 structure poleward of 75 latitude at altitudes of 62 km

displacement transfer between intersecting regional strike slip and extensional fault systems interaction and displacement transfer between active intersecting strike slip or transform and extensional fault systems are examined outcrop data from a well preserved strike slip fault and rift intersection in new zealand are compared to a global data set of 13 such intersections in both continental and oceanic crust displacement transfer between strike slip and normal faults is typically accomplished by gradual changes of fault orientations and slip vectors close to the intersection zone for two and three plate configurations these changes result in sub parallelism of the slip vectors of the component faults with their line of intersection the dimensions of the area over which fault strike and slip vectors change are principally controlled by the extent to which displacements on the dominant of the two intersecting fault systems are confined to a single slip surface or distributed across a zone where slip is spatially distributed the region in which the two displacement fields are superimposed produces transtension and associated oblique slip this distributed off fault deformation facilitates the development of a quasi stable configuration of the fault intersection region maintaining both the regional geometry and kinematics of the intersection zone which in many cases would not be possible for rigid block translations the dimensions of the transition zone are larger for continental crust than for oceanic crust because oceanic crust is thinner fault geometries in oceanic crust are simpler two plate configurations and the slip vectors of the component intersecting fault systems are sub parallel

porosity and packing of holocene river dune and beach sands the porosity and packing of 174 samples of surficial and shallowly buried to 17 m unconsolidated holocene sands medium to coarse grained were determined by point counting the upper surface of thin sections of epoxy impregnated samples in reflected light average depositional porosity for 124 surficial sands from beaches river point bars and braid bars and eolian dunes respectively is 47 48 and 49 the porosity values range between 40 and 58 beach sands exhibit an average packing value ci contact index of 0 79 fluvial sands an average ci of 0 91 and eolian sands an average ci of 1 02 beach sands typically contain 5 5 oversized pores river sands 3 8 oversized pores and eolian dune sands 4 0 oversized pores most oversized pores are depositional packing defects although trapped air bubbles are common in some beach sands extrapolation of our data for buried samples indicates depositional oversized pores are destroyed at a depth of less than 100 m average porosity is 46 for eolian ripple strata 50 for grain fall strata and 51 for grain flow strata differences in packing are significant for grain flow versus grain fall strata and for ripple versus grain flow strata for samples of similar grain size porosity is more uniform within individual beds from a river and a beach than among different beds at the same localities porosity of ancient sandstones from a particular bed or facies may be as uniform as sampled holocene sands unless cements having patchy distribution such as carbonate or anhydrite are present compaction associated with burial to 17 m is minor packing is tighter but our technique of measuring porosity is not sensitive enough to show any decrease in porosity changes in packing and porosity upon burial to common hydrocarbon reservoir depths will depend on individual histories of cementation compaction and secondary porosity development however if only physical compaction of quartzose river dune and beach sands takes place porosity would approach a limiting value of 26 and ci would approach 5 5

planetary boundary layer and slope winds on venus few constraints are available to characterize the deep atmosphere of venus though this region is crucial to understand the interactions between surface and atmosphere on venus based on simulations performed with the ipsl venus global climate model the possible structure and characteristics of venus planetary boundary layer pbl are investigated the vertical profile of the potential temperature in the deepest 10 km above the surface and its diurnal variations are controlled by radiative and dynamical processes the model predicts a diurnal cycle for the pbl activity with a stable nocturnal pbl while convective activity develops during daytime the diurnal convective pbl is strongly correlated with surface solar flux and is maximum around noon and in low latitude regions it typically reaches less than 2 km above the surface but its vertical extension is much higher over high elevations and more precisely over the western flanks of elevated terrains this correlation is explained by the impact of surface winds which undergo a diurnal cycle with downward katabatic winds at night and upward anabatic winds during the day along the slopes of high elevation terrains the convergence of these daytime anabatic winds induces upward vertical winds that are responsible for the correlation between height of the convective boundary layer and topography

investigation of air temperature on the nightside of venus derived from virtis h on board venus express abstract we present the spatial distribution of air temperature on venus night side as observed by the high spectral resolution channel of virtis visible and infrared thermal imaging spectrometer or virtis h on board the esa mission venus express the present work extends the investigation of the average thermal fields in the northern hemisphere of venus by including the virtis h data we show results in the pressure range of 100 4 mbar which corresponds to the altitude range of 65 80 km with these new retrievals we are able to compare the thermal structure of the venus mesosphere in both hemispheres the major thermal features reported in previous investigations i e the cold collar at about 65 70 s latitude 100 mbar pressure level and the asymmetry between the evening and morning sides are confirmed here by comparing the temperatures retrieved by the virtis spectrometer in the north and south we find that similarities exist between the two hemispheres solar thermal tides are clearly visible in the average temperature fields to interpret the thermal tide signals otherwise impossible without day site observations we apply model simulations using the venus global circulation model venus gcm lebonnois s hourdin f forget f eymet v fournier r 2010b international venus conference aussois 20 26 june 2010 of the laboratoire de meteorologie dynamique lmd we suggest that the signal detected at about 60 70 latitude and pressure of 100 mbar is a diurnal component while those located at equatorial latitudes are semi diurnal other tide related features are clearly identified in the upper levels of the atmosphere

calcite sealing in a fractured geothermal reservoir insights from combined ebsd and chemistry mapping fractures play an important role as fluid flow pathways in geothermal resources hosted in indurated greywacke basement of the taupo volcanic zone new zealand including the kawerau geothermal field over time the permeability of such geothermal reservoirs can be degraded by fracture sealing as minerals deposit out of transported geothermal fluids calcite is one such fracture sealing mineral this study for the first time utilises combined data from electron backscatter diffraction and chemical mapping to characterise calcite vein fill morphologies and gain insight into the mechanisms of calcite fracture sealing in the kawerau geothermal field two calcite sealing mechanisms are identified 1 asymmetrical syntaxial growth of calcite inferred by the presence of single twinned calcite crystals spanning the entire fracture width and 2 3d interlocking growth of bladed vein calcite into free space as determined from chemical and crystallographic orientation mapping this study also identifies other potential uses of combined ebsd and chemical mapping to understand geothermal field evolution including potentially informing on levels of fluid supersaturation from the study of calcite lattice distortion and providing information on a reservoir s history of stress strain and deformation through investigation of calcite crystal deformation and twinning patterns

formation of rhyolite at the okataina volcanic complex new zealand new insights from analysis of quartz clusters in plutonic lithics granitoid lithic clasts from the 0 7 ka kaharoa eruption at the tarawera volcano okataina volcanic complex taupo volcanic zone new zealand provide insight into the processes of rhyolite formation the plutonic lithic clasts of the kaharoa eruption consist of 1 quartz phenocrysts which are often grouped into clusters of two to eight quartz grains 2 plagioclase phenocrysts mostly an 40 with up to an 60 cores and 3 interstitial alkali feldspar quartz orientations obtained through electron backscatter diffraction ebsd methods show that 78 of the 82 analyzed clusters have at least one pair of quartz grains with the dominant dipyramidal faces matched variations in cathodoluminescence cl zoning patterns of the quartz suggest that quartz clusters came together after initial crystal growth and that many quartz crystals were subject to one or more resorption events the process of quartz crystals with different magmatic histories coming together into common relative orientations to form clusters is indicative of oriented quartz synneusis and suggests a history of crystal accumulation the quartz clusters are interpreted to have formed as part of a crystal cumulate mush within a shallow magma chamber where quartz crystals rotated into contact along their dominant dipyramidal faces during hindered settling and or compaction the preservation of oriented quartz clusters from the kaharoa plutonic lithics thus provides evidence for synchronous shallow pluton formation from a cumulate mush during active silicic volcanism this result is consistent with models whereby melt rich high silica rhyolite formation occurs via interstitial melt extraction from a low silica rhyolite mush in the shallow crust

rapid evolution of subduction related continental intraarc rifts the taupo rift new zealand the evolution of the continental intra arc taupo rift in the north island new zealand is rapid significantly faster than comparative intra continental rifts such as the african rifts based on our faulting data and published geological geophysical and borehole data we show that activity in the 2 ma taupo rift has rapidly and asymmetrically narrowed via inward and eastward migration of faulting at rates of ca 30 km my 1 and 15 km my 1 respectively and has propagated southwards along its axis 70 km in 350 kyr the loci of voluminous volcanic eruptions and active faulting are correlated in time and space suggesting that a controlling factor in the rapid rift narrowing is the presence of large shallow heterogeneities in the crust such as large rhyolitic magma bodies generated by subduction processes which weaken the crust and localize deformation eastward migration of faulting also follows the eastward migration of the volcanic arc which may be related to rollback of the pacific crust slab at the hikurangi subduction zone southward propagation of the rift is linked with southward migration of the hikurangi plateau chatham rise subduction point and occurs episodically aided by stress changes associated with voluminous local volcanism the large magma supply during early continental intra arc rift stages explains faster evolution from tectonic to magmatic than intracontinental rifts however the fast changes in magma supply from the subduction zone can also lead to evolution reversals more evolved magmatic stages reverting to less evolved tectonic stages rift cessation and thus failed continental break up

geometry and kinematics of active faults and their seismotectonic significance in the western corinth patras rift greece abstract the western part of the corinth patras rift is formed in an area which is being uplifted rifted domains have subsided relative to the adjacent areas in nw peloponnesus and sterea hellas but subsidence rates rarely exceed uplift rates extension is mainly accomplished by wnw trending active faults with lengths up to 25 km most of these faults show an along strike segmentation and often terminate against transfer faults displacement analysis along 170 mesoscopic faults and 36 mappable faults has been carried out to assess slip rates and to estimate the magnitudes and recurrence time intervals of earthquakes occurring along them earthquake magnitude ranges between 5 and 6 7 only eight faults appear to be capable of producing earthquake magnitudes larger than 6 recurrence times of these large earthquakes vary between 80 and 1690 years upper crustal deformation in the western corinth graben can be described by six large asymmetric grabens which are inferred to bottom out to a n dipping curved ramp the asymmetric shape of most wnw trending rifts in the hellenic peninsula including the corinth patras rift promotes the simple shear model of extension against the pure shear model in the upper crustal layer

morphotectonic analysis of the long term surface expression of the 2009 l aquila earthquake fault central italy using airborne lidar data abstract in this paper we present a morphotectonic study of the paganica san demetrio fault system psdfs responsible for the mw6 1 april 6 2009 earthquake l aquila central italy the discrepancy observed between the length of the seismologic geodetic modeled fault the limited size of the primary coseismic surface ruptures and the significant morphological expression of the psdfs stimulated a debate about the maximum rupture length of the psdfs and its capability to generate larger magnitude events to image the psdfs long term morphological expression and define its surface geometrical arrangement length number of fault splays and boundaries we took advantage of a high resolution airborne lidar dataset lidar topography substantially increased our confidence in detecting even subtle tectonic controlled morphologies we define the psdfs as a 19 km long fault system that displays a complex structural setting characterized by two different sectors 1 the paganica sector to the nw with a narrow deformation zone and 2 the san demetrio sector to se where the strain is accommodated by several fault splays dissecting a wider quaternary basin we also defined a first order hierarchy among the numerous fault splays across the psdfs the long term geomorphic expression of the psdfs suggests that it ruptured also involving the whole 19 km long structure besides rupturing only small sections as it occurred in 2009 this suggests a variable slip behavior empirical relations applied to this hypothesis allow up to m 6 6 earthquakes along the psdfs these results have a critical impact on the seismic hazard assessment of the area when compared with a m 6 1 event as the 2009

timing of the late glacial climate reversal in the southern hemisphere using high resolution radiocarbon chronology for kaipo bog new zealand abstract the pattern of climate change in the southern hemisphere during the younger dryas yd chronozone provides essential constraint on mechanisms of abrupt climate change only if accurate high precision chronologies are obtained a climate reversal reported previously at kaipo bog new zealand had been dated between 13 600 and 12 600 cal yr b p and appeared to asynchronously overlap the yd chron but the chronology based on conventionally radiocarbon dated bulk sediment samples left the precise timing questionable we report a new high resolution ams 14 c chronology for the kaipo record that confirms the original chronology and provides further evidence for a mid latitude southern ocean cooling event dated between 13 800 and 12 400 cal yr b p 2 range roughly equivalent to the antarctic cold reversal

national seismic hazard model for new zealand 2010 update a team of earthquake geologists seismologists and engineering seis mologists has collectively produced an update of the national probabilistic seismic hazard psh model for new zealand national seismic hazard model or nshm the new nshm supersedes the earlier nshm published in 2002 and used as the hazard basis for the new zealand loadings standard and numerous other end user applica tions the new nshm incorporates a fault source model that has been updated with over 200 new onshore and offshore fault sources and utilizes new new zealand based and international scaling relationships for the parameterization of the faults the dis tributed seismicity model has also been updated to include post 1997 seismicity data a new seismicity regionalization and improved methodology for calculation of the seismicity parameters probabilistic seismic hazard maps produced from the new nshm show a similar pattern of hazard to the earlier model at the national scale but there are some significant reductions and increases in hazard at the regional scale the national scale differences between the new and earlier nshm appear less than those seen between much earlier national models indicating that some degree of consis tency has been achieved in the national scale pattern of hazard estimates at least for return periods of 475 years and greater online material table of fault source parameters for the 2010 national seismic hazard model

cloud tracked winds from pioneer venus ocpp images abstract analysis of ultraviolet image sequences obtained from the pioneer venus orbiter cloud photopolarimeter and covering five 80 day periods from 1979 1985 provides the first climatological description of the cloud top circulation on venus the average zonal winds can be characterized as a 5 day retrograde rotation of the whole cloud level atmosphere with weak jets at middle to high latitudes both the midlatitude and equatorial zonal winds vary by about 5 8 m s 1 over time spans of 1 6 years the average meridional circulation is poleward in both hemispheres up to at least 60 latitude consistent with the presence of a thermally direct hadley circulation associated with the clouds the strength of the hadley circulation also varies with time four wave modes are clearly identified a diurnal solar tide a semi diurnal solar tide a 4 day equatorial wave and a 5 day midlatitude wave the semidiurnal tide appears to have an amplitude of about 5 m s 1 and to be approximately constant with time

fingerprints and age models for widespread new zealand tephra marker beds erupted since 30 000 years ago a framework for nz intimate abstract the role of tephras in the nz intimate project is a critical one because most high resolution palaeoclimatic records are linked and dated by one or more tephra layers in this review first we document eruptive distributional and compositional fingerprinting data both mineralogical and geochemical for 22 key marker tephras erupted since 30 000 years ago to facilitate their identification and correlation we include new glass compositional data the selected marker tephras comprise 10 from taupo and nine from okataina volcanoes rhyolitic one from tuhua volcano peralkaline rhyolitic and one each from tongariro and egmont volcanoes andesitic second we use four approaches to develop 2 age models for the tephras youngest to oldest 1 calendar ages for kaharoa and taupo y were obtained by wiggle matching log derived tree ring sequences dated by 14c 2 whakaipo v was dated using an age depth model from peat 3 14 tephras in the montane kaipo peat sequence waimihia s unit k whakatane tuhua mamaku rotoma opepe e poronui c karapiti b okupata konini waiohau rotorua rerewhakaaitu were dated by simultaneously wiggle matching stratigraphic position and 51 independent 14c age points against intcal04 using bayesian probability methods via both oxcal and bpeat and 4 the five oldest tephras erupted before ca 18 000 cal yr bp were dated by calibrating limited numbers of 14c ages using intcal04 okareka or comparison curves of the expanded cariaco basin sequence te rere kawakawa oruanui poihipi okaia kawakawa oruanui tephra the most widely distributed marker tephra was erupted probably ca 27 097 957 cal yr bp potential dating approaches for the older tephras include their identification in antarctic ice cores if present or annually laminated sediments for which robust calendar age models have been constructed high precision ams 14c dating on appropriate material from environmentally stable sites systematic luminescence dating or new radiometric techniques e g u th he if suitable minerals are available and errors markedly reduced further application of bayesian age modelling to stratigraphic sequences of 14c ages possibly augmented with luminescence ages may help refine age models for pre holocene tephras with the largest errors finally we discuss the critical role these marker tephras play in the ongoing construction of an event stratigraphy for the new zealand region which is a key objective of australasian and southern hemisphere intimate projects