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

coseismic and postseismic stress changes in a subducting plate possible stress interactions between large interplate thrust and intraplate normal faulting earthquakes 1 a large intraplate normal faulting earthquake mw 7 5 occurred in 1999 in the subducting cocos plate below the downdip edge of the ruptured thrust fault of the 1978 oaxaca mexico earthquake mw 7 8 this situation is similar to the previous case of the 1997 normal faulting event mw 7 1 that occurred beneath the rupture area of the 1985 michoacan mexico earthquake mw 8 1 we investigate the possibility of any stress interactions between the preceding 1978 thrust and the following 1999 normal faulting earthquakes for this purpose we estimate the temporal change of the stress state in the subducting cocos plate by calculating the slip distribution during the 1978 earthquake through teleseismic waveform inversion the dynamic rupture process and the resultant coseismic stress change together with the postseismic stress variations due to plate convergence and the viscoelastic relaxation process to do this we calculate the coseismic and postseismic changes of all stress components in a three dimensional space incorporating the subducting slab the overlying crust and uppermost mantle and the asthenosphere for the coseismic stress change we solve elastodynamic equations incorporating the kinematic fault slip as an observational constraint under appropriate boundary conditions to estimate postseismic stress accumulations due to plate convergence a virtual backward slip is imposed to lock the main thrust zone the effects of viscoelastic stress relaxations of the coseismic change and the back slip are also included the maximum coseismic increase in the shear stress and the coulomb failure stress below the downdip edge of the 1978 thrust fault is estimated to be in the range between 0 5 and 1 5 mpa and the 1999 normal faulting earthquake was found to take place in this zone of stress increase the postseismic variations during the 21 years after the 1978 event modify the magnitude and patterns of the coseismic stress change to some extent but are not large enough to overcome the coseismic change these results suggest that the coseismic stress increase due to the 1978 thrust earthquake may have enhanced the chance of occurrence of the 1999 normal faulting event in the subducting plate if this is the case one of the possible mechanisms could be static fatigue of rock materials around preexisting weak planes involved in the subducting plate and it is speculated that that one of these planes might have been reactivated and fractured because of stress corrosion cracking under the applied stress there for 21 years

kinematics of the philippine sea plate in this study new instantaneous rotation vectors describing the motion of the philippine sea plate relative to surrounding plates are determined that most nearly satisfy all available geological geophysical and seismological observations along the plate margins pacific philippine and caroline pacific poles are generated from a set of trial eurasia philippine poles of rotation using published determinations of the eurasia pacific and caroline philippine poles the pacific philippine caroline pacific and eurasia philippine poles are then checked for agreement with 1 slip vectors determined from focal mechanisms of earthquakes along the ryukyu trench and the nankai trough 2 convergence at the sagami trough 3 extension in the mariana trough 4 extension behind the bonin trench 5 extension in the western sorol trough and 6 convergence at the mussau trench trial eurasia philippine poles are eliminated if predicted plate motions do not match observed plate motions the locations and rotation rates of the three best fitting poles are eurasia philippine 37 0 n 141 0 e 1 60 ma pacific philippine 3 8 n 130 4 e 1 68 ma caroline pacific 16 9 n 141 4 e 0 54 ma the plate motions predicted by these new poles are compared with the spatial distribution of earthquakes and new focal mechanism solutions in the complex region where the philippine pacific and caroline plates intersect intermediate and deep focus earthquake hypocenters along the southern mariana arc show a southward decrease in the length of the seismic zone which qualitatively agrees with the predicted convergence rate as the pole of rotation is approached and as the effect of back arc spreading in the mariana trough disappears the absence of volcanism and intermediate depth seismicity along the southernmost mariana yap and palau sections of the plate boundary is attributed to very low convergence rates a new focal mechanism solution along the trench south of guam is the first clear underthrusting solution found along the mariana trench and agrees with the convergence direction implied by the pacific philippine pole of rotation no clear underthrusting focal mechanism solutions were found along the yap and palau trenches although three high angle thrust solutions demonstrate that compression is occurring in the upper plate perpendicular to the plate boundary

block modeling with connected fault network geometries and a linear elastic coupling estimator in spherical coordinates geodetic observations of interseismic deformation provide constraints on the partitioning of fault slip across plate boundary zones the spatial distribution of both elastic and inelastic strain accumulation and the nature of the fault system evolution here we describe linear block theory which decomposes surface velocity fields into four components 1 plate rotations 2 elastic deformation from faults with kinematically consistent slip rates 3 elastic deformation from faults with spatially variable coupling and 4 homogeneous intrablock strain elastic deformation rates are computed for each fault segment in a homogeneous elastic half space using multiple optimal planar cartesian coordinate systems to minimize areal distortion and triangular dislocation elements to accurately represent complex fault system geometry block motions fault slip rates elastic coupling and internal block strain rates are determined simultaneously using a linear estimator with constraints from both geodetically determined velocity fields and geologic fault slip rate estimates we also introduce algorithms for efficiently implementing alternative fault network geometries to quantify parameter sensitivity to nonlinear perturbations in model geometry

estimation of slip distribution using an inverse method based on spectral decomposition of green s function utilizing global positioning system gps data 1 an inverse method based on the spectral decomposition of the green s function was employed for estimating a slip distribution we conducted numerical simulations along the philippine sea plate ph boundary in southwest japan using this method to examine how to determine the essential parameters which are the number of deformation function modes and their coefficients japanese gps earth observation network geonet global positioning system gps data were used for three years covering 1997 1999 to estimate interseismic back slip distribution in this region the estimated maximum back slip rate is about 7 cm yr which is consistent with the philippine sea plate convergence rate areas of strong coupling are confined between depths of 10 and 30 km and three areas of strong coupling were delineated these results are consistent with other studies that have estimated locations of coupling distribution

compositional maps of saturn s moon phoebe from imaging spectroscopy the origin of phoebe which is the outermost large satellite of saturn is of particular interest because its inclined retrograde orbit suggests that it was gravitationally captured by saturn having accreted outside the region of the solar nebula in which saturn formed by contrast saturn s regular satellites with prograde low inclination circular orbits probably accreted within the sub nebula in which saturn itself formed here we report imaging spectroscopy of phoebe resulting from the cassini huygens spacecraft encounter on 11 june 2004 we mapped ferrous iron bearing minerals bound water trapped co2 probable phyllosilicates organics nitriles and cyanide compounds detection of these compounds on phoebe makes it one of the most compositionally diverse objects yet observed in our solar system it is likely that phoebe s surface contains primitive materials from the outer solar system indicating a surface of cometary origin

interplate coupling in northeast japan deduced from inversion analysis of gps data abstract the spatial distribution of the strength of interplate coupling between the subducting pacific plate and the overlying continental plate in northeast japan was investigated through an inversion analysis of gps data employing akaike s bayesian information criterion the gps data used for the inversion analysis are rates of baseline length changes and vertical displacement rates of crustal movements during the period from april 6 1996 to march 20 1998 which were obtained at 161 continuous gps observation stations operated by the geographical survey institute of japan the result shows the average drag rates of the overriding plate on the model source regions off the tohoku and hokkaido districts are 6 7 cm yr and 6 8 cm yr respectively which are 0 85 and 0 87 as interplate coupling ratio these values are much higher than those in previous studies the average directions of drag rates are oriented n73 w 15 and n78 w 13 on the model source regions off the tohoku and hokkaido districts respectively these directions agree well with the direction of coseismic slip of the foot wall side n75 w of the 1978 miyagiken oki earthquake m 7 4 but differ slightly from the direction estimated from the plate motion model n65 w seno et al j geophys res 101 1996 11305 11315 we also found afterslip of 5 5 cm yr associated with the 1994 sanriku haruka oki earthquake m 7 5 off aomori prefecture interestingly enough large afterslip occurred on the plate boundary even when more than a year had passed after the sanriku haruka oki earthquake the amount of drag rate becomes dramatically small at depths greater than about 50 km on the model source regions indicating weak interplate coupling there

viscoelastic cycle model of interseismic deformation in the northwestern united states summary we apply a viscoelastic cycle model to a compilation of gps velocity fields in order to address the kinematics of deformation in the northwestern united states a viscoelastic cycle model accounts for time dependent deformation following large crustal earthquakes and is an alternative to block models for explaining the interseismic crustal velocity field building on the approach taken in pollitz et al we construct a deformation model for the entire western united states based on combined fault slip and distributed deformation and focus on the implications for the mendocino triple junction mtj cascadia megathrust and western washington we find significant partitioning between strike slip and dip slip motion near the mtj as the tectonic environment shifts from northwest directed shear along the san andreas fault system to east west convergence along the juan de fuca plate by better accounting for the budget of aseismic and seismic slip along the cascadia subduction interface in conjunction with an assumed rheology we revise a previous model of slip for the m 9 1700 cascadia earthquake in western washington we infer slip rates on a number of strike slip and dip slip faults that accommodate northward convergence of the oregon coast block and northwestward convergence of the juan de fuca plate lateral variations in first order mechanical properties e g mantle viscosity vertically averaged rigidity explain to a large extent crustal strain that cannot be rationalized with cyclic deformation on a laterally homogeneous viscoelastic structure our analysis also shows that present crustal deformation measurements particularly with the addition of the plate boundary observatory can constrain such lateral variations

deformation of the japanese islands and seismic coupling an interpretation based on gsi permanent gps observations summary the entire area of the japanese islands has been covered by the permanent gps observation network of the geographical survey institute since 1994 in this paper we use a solution for the vectors of motion during 1995 for a selection of 116 stations to discuss the origin of the observed deformation field we refer the displacement field to eurasia using the vlbi determined motion of kashima and demonstrate that other choices such as the okhotsk or north american plates for north japan are not compatible with the data 1 yr gps velocities are much higher than geological constraints would allow because these short term measurements include transient elastic deformation however the good qualitative agreement between the observed geodetic deformation tensors and those inferred from active faults and earthquakes suggests that the quaternary permanent deformation is essentially the result of the transfer of part of the subduction induced elastic deformation into permanent plastic deformation we then compute the elastic deformation of the japanese islands caused by interseismic loading of the pacific and philippine subduction planes the geometry of the coupled zone and its downward extension are determined from the distribution of earthquakes for the pacific slab for the philippine slab we use the geometry proposed by hyndman et al 1995 these elastic models account for most of the observed velocity field if the subduction movement of the philippine sea plate is 100 per cent locked and if that of the pacific plate is 75 85 per cent locked we note that the boundaries of the areas where significant elastic deformation is predicted more than 10 mm yr 1 of motion with respect to eurasia coincide with the main zones of permanent deformation the eastern japan sea deformation zone for the pacific subduction elastic deformation field and the setouchi mtl deformation zone for the nankai field each zone probably accommodates 10 15 mm yr 1 of motion in the long term convergence in the eastern japan sea strike slip in the setouchi mtl zone to account for this deformation the evect of elastic loading from the trench must be combined with 5 10 mm yr 1 of motion of the amur plate with respect to eurasia because loading during the subduction earthquake cycle causes an increase in stress in the eastern japan sea and setouchi mtl deformation zones the probability of earthquake occurrence in these zones may be higher near the end of the cycle

tectonic evolution of the japanese island arc system abstract growth of the japanese arc system which has mainly taken place along the continental margin of asia since the permian is the result of subduction of the ancient pacific ocean floor backarc basin formation in the tertiary shaped the present day arc configuration the neotectonic regime which is characterized by strong east west compression has been triggered by the eastward motion of the amur plate in the quaternary the tectonic evolution of the japanese arc system includes formation of rock assemblages common in most orogenic belts because the origin and present day tectonics of these assemblages are better defined in the case of the japanese arc system study of the system provides useful insight into orogenesis and continental crust evolution

iapetus surface variability revealed from statistical clustering of a vims mosaic the distribution of co2 abstract we present a detailed study of an iapetus mosaic of vims data with high spatial resolution 0 5 0 5 or 6 4 km pixel the spectra were taken in august 2007 and provide the highest vims spatial resolution data for this object during cassini s primary mission we analyze this set of data using a statistical clustering approach to reduce the analysis of a large number of data 10 4 spectra from 0 35 to 5 10 m to the study of seven representative groups accounting for 99 6 of the surface covered by the original sample we analyze the spectral absorption bands in the spectra of the different clusters indicative of different composition over the observed surface we find coherence between the distribution of the clusters and the geographical features on the surface we give special attention to the study of the water ice and co 2 bands we find that co 2 is widespread over the entire surface being studied including the bright and dark areas on iapetus surface and is probably trapped at the molecular level with other materials the strength of the co 2 band in the areas where both h 2 o and carbon bearing materials exist gives support to the hypothesis that this volatile is formed on the surface of iapetus as a product of irradiation of these two components finally we also compare the iapetus co 2 with that on other satellites confirming that there are evident differences on the center depth and width of the band on iapetus and phoebe where co 2 has been suggested to be endogenous

incipient subduction and deduction along the eastern margin of the japan sea the eastern margin of the japan sea has been under convergent tectonics since sometime after the pliocene the suture line is on the ocean continent boundary between the japan yamato basins and the tohoku northeast japan arc incipient subduction and obduction of the oceanic and sub oceanic crust are observed along the suture line with the occurrence of numerous n s trending fault bounded ridges and troughs focal mechanism solutions of several compressional type earthquakes with magnitudes of m 6 9 to 7 7 which have occurred along the zone are consistent with the observation of geological thrust faults the convergent stresses in the japan sea may be due to india eurasia collision and its associated intra plate or inter microplate movements in east asia the eastward movement of the amurian plate causes baikal extension along its western margin and the japan sea convergence along its eastern margin

intraplate deformation in the japanese islands a kinematic study of intraplate deformation at a convergent plate margin relative motions within the deforming japanese islands with respect to the sea of japan are determined using earthquake records over the last 414 years slip rates on quaternary faults and angular change rates obtained from triangulation in the last century we use a least squares inversion method to match the strain rates on the surface of the earth with continuous spline functions to recover the velocity gradient tensors the directions of the principal strain axes obtained from seismic geological and geodetic data are in general agreement with each other with the maximum shortening axis oriented in a wnw direction principal strain rate magnitudes obtained from the geodetic data are about 3 5 times larger than the principal strain rates obtained from the seismic and geological data intraplate deformation in southwestern japan determined from the seismic data accommodates a velocity of5 5 2 l mm yr in a direction parallel to the nankai trough which is about 25 of the plate motion velocity component parallel to the nankai trough between the philippine sea and eurasian plates in northern honshu the velocity vectors from the seismic data are nearly parallel to the plate motion vector at the japan trench and the intraplate deformation accommodates about 6 of the total pacific eurasian or north american plate motion velocity the velocity vector at kashima northern honshu calculated from the geodetic data is about 9 12 mm yr in a direction of n55 w n76 w which is about half of the very long baseline interferometry velocity calculated in the eurasian reference frame suggesting that the sea of japan may not be rigidly attached to the assumed rigid eurasian plate

deep structure of the mozumi sukenobu fault central japan estimated from the subsurface array observation of fault zone trapped waves summary in order to estimate the averaged fault zone structure i e the width shear wave velocity and qs of the mozumi sukenobu fault central japan we analysed the love wave type fault zone trapped waves recorded by a seismic array deployed in a subsurface survey gallery we selected the typical love wave type trapped waves based on the characteristics of dispersion amplitude apparent velocity and the polarization of wave trains following the direct shear wave we selected nine events showing typical love wave type trapped waves from 154 earthquakes epicentres of the events were located along the surface trace of the mozumi sukenobu fault the nine events showing trapped waves were found to be located in a plane dipping to the south at an angle of approximately 75 to 85 the duration of the fault zone trapped waves increase non linearly with the increase of hypocentral distance this result implies an increase in shear wave velocity of the fault zone with depth and or horizontal distance from the array in order to obtain averaged fault zone structure from hypocentre to receiver we assumed fault zone structure to be a 2 d uniform low velocity waveguide and modelled the dispersion curve and the waveform of trapped waves using an analytical solution the width shear wave velocity and qs of the fault zone were estimated to be 160 to 400 m 2 9 to 3 1 km s 1 and 60 to 90 respectively the width of the fault zone estimated in this analysis is consistent with the width of the extent of fault zone at the survey gallery we also conducted 3 d finite difference simulation 3 d fdm on fault zone trapped waves using depth dependent structure models referred to the 2 d averaged structure indicating the possible depth dependent structures the 2 d modelling is useful as an initial guide to the 3 d imaging of a fault zone

crustal block kinematics and seismic potential of the northernmost philippine sea plate and izu microplate central japan inferred from gps and leveling data 1 we clarify the contemporary deformation observed by gps and leveling for the greater tokyo kanto eastern tokai and the izu islands region where the izu ogasawara bonin arc is subducting and colliding with the central part of the japan arc from these data we develop a kinematic model of fault sources with variable components of seismic and aseismic slip under the assumption that the contemporary deformation during 1995 2000 is representative of the long term interseismic strain field the geodetic data are inverted to estimate the rotation poles of the crustal blocks the degree of elastic strain accumulation on faults and the volumetric inflation sources beneath volcanoes the present crustal movements are explained by four crustal blocks the izu microplate the central japan block the pacific plate and the philippine sea plate along the suruga and sagami margins of the philippine sea plate lie strongly coupled faults which include sites of the 1854 m 8 4 tokai 1923 m 7 9 kanto and 1703 m 8 2 genroku kanto earthquakes in contrast the philippine sea plate boundary immediately north of the izu peninsula site of m 7 5 collisional earthquakes is only weakly coupled the boundary between the izu microplate and the philippine sea plate experiences left lateral motion with the rate of 30 mm yr most of this boundary is locked and thus has a large potential of future earthquakes the izu microplate is found to rotate rapidly clockwise at 10 myr with a rotation pole relative to the central japan block located just north of its northern boundary the pole and angular velocity of the izu microplate depends however on the assumed location of the boundary with the exception of the site of the 1938 m 7 earthquake swarm which we infer has the current potential to produce a m 8 1 earthquake the pacific megathrust has a very low seismic potential although the geodetic data have little resolving power for much of the pacific plate interface east of tokyo

strike slip tectonics within the northernmost philippine sea plate in an arc continent collisional setting abstract the geological processes in the northernmost philippine sea plate which is bounded by the suruga and sagami troughs are a typical example of an active collision zone we attempt to illustrate the stress field through seismic estimations and geodetic analysis and propose the kinematic mode of the northernmost tip of the philippine sea plate seven events m 4 0 are chosen for waveform inversion by the isola software to distinguish the stress field in particular six of the chosen events which exhibit strike slip motion are distributed in the eastern area where few focal mechanisms have been reported by previous studies according to the available focal mechanisms strike slip faults with similar p and t axes are widely distributed in the study area the stress inversion suggests that the northern area is characterized by a nw se compression and a ne sw extension stress regime although some spatial differences exist as indicated by an analysis of the geodesy epicenters focal mechanisms gravity anomalies and velocity structure the deformation in the northernmost tip is mainly accommodated by several conjugate strike slip fault systems with steep dips that center on the izu volcanic line generally the maximum principal stress of the kinematics is derived from the collision between the philippine sea plate and central japan because of the different subduction angles rates and directions of the down going plate diverging slab pull forces along the suruga and sagami troughs may be causing the ne nne extension in most of the areas that are bounded by the two troughs the extension propagates southwards along the izu volcanic line and reaches the area adjacent to miyake jima

tectonic model and fault segmentation of the median tectonic line active fault system on shikoku japan 1 fault segmentation models have been developed by using various types of information about faults including both geological and geophysical data in order to predict the size of future cascade earthquakes in these models however stress conditions within the fault systems have not been considered in sufficient detail major fault systems generally exhibit heterogeneous stress conditions the median tectonic line active fault system mtlafs is the longest and most active arc parallel right lateral strike slip fault system in japan the stress conditions along the mtlafs change from transpression on eastern shikoku island to transtension on kyushu island the change of stress conditions along the fault system is caused by the counterclockwise rotation of the nankai fore arc sliver in response to the relative motion of the philippine sea and eurasian tectonic plates and back arc spreading in the okinawa trough here we propose stress condition segmentation as a concept that deals with the diversity of stress conditions and can be applied in seismic hazard assessment according to this concept the mtlafs is divided into three segments the east shikoku west shikoku and kyushu segments the east shikoku and kyushu segments are under compressional and tensional stress conditions respectively stress in the west shikoku segment which is between the other two segments is transitional from compressional to tensional conditions in particular change in the magnitude of fault normal stresses along strike is one of the key factors that govern the geometry of fault discontinuities rupture propagation and termination and consequently fault segmentation application of our stress condition segmentation concept to the mtlafs suggests that future earthquakes in the west shikoku and kyushu segments will be of lower energy than those in the east shikoku segment

plate tectonics and crustal deformation around the japanese islands we analyze over a century of geodetic data to study crustal deformation and plate motion around the japanese islands using the block fault model for crustal deformation developed by matsu ura et al 1986 in this model crustal deformation corresponds to the sum of relative movement among designated blocks and displacement due to dislocations along the locked parts of designated faults we model the area including the japanese islands with 19 crustal blocks and 104 faults based on the distribution of active faults and seismicity three kinds of data are used rates of change of angles and lengths and average velocities of very long baseline interferometry stations with the inversion of these geodetic data we obtain block motions and average slip rates of faults this geodetic model predicts that the pacific plate moves n69 2 w at about 80 3 mm yr relative to the eurasian plate which is much lower than that predicted in geologic models substantial aseismic slip occurs on the subduction boundaries the block containing the izu peninsula may be separated from the rigid part of the philippine sea plate the faults on the coast of japan sea and the western part of the median tectonic line have slip rates exceeding 4 mm yr while the fossa magna does not play an important role in the tectonics of the central japan the geodetic model requires the division of northeastern japan contrary to the hypothesis that northeastern japan is a part of the north american plate owing to rapid convergence the seismic risk in the nankai trough may be larger than that of the tokai gap

configuration of the subducting philippine sea slab in the eastern part of southwestern japan with seismic array and hi net data abstract it is important to know the shape of a subducting slab in order to understand the mechanisms of inter plate earthquakes and the process of subduction seismicity data and converted phases have been used to detect plate boundaries the configuration of the philippine sea slab has been obtained at the western part of southwestern japan at the eastern part of southwestern japan however the configuration of the philippine sea slab has not yet been confirmed a spatially high density seismic network makes it possible to detect the boundaries of the philippine sea slab we used a spatially high density temporal seismic array in the area the configuration of the philippine sea plate is obtained at the eastern part of southwestern japan using the temporal seismic array and permanent seismic network data and comparing the seismic structure obtained from the results of refraction surveys the configuration of the philippine sea plate obtained by this study does not bend sharply compared to previous models obtained from receiver function analyses we delineated the upper boundary of the slab to a depth of about 45 km the weak image of the boundary which corresponds to the upper mantle reflector beneath the source area of the 2000 western tottori earthquake was detected using the spatially dense array

cassini vims observations of the galilean satellites including the vims calibration procedure the visual and infrared mapping spectrometer vims observed the galilean satellites during the cassini spacecraft s 2000 2001 flyby of jupiter providing compositional and thermal information about their surfaces the cassini spacecraft approached the jovian system no closer than about 126 jupiter radii about 9 million kilometers at a phase angle of 90 resulting in only sub pixel observations by vims of the galilean satellites nevertheless most of the spectral features discovered by the near infrared mapping spectrometer nims aboard the galileo spacecraft during more than four years of observations have been identified in the vims data analyzed so far including a possible 13c absorption in addition vims made observations in the visible part of the spectrum and at several new phase angles for all the galilean satellites and the calculated phase functions are presented in the process of analyzing these data the vims radiometric and spectral calibrations were better determined in preparation for entry into the saturn system treatment of these data is presented as an example of the vims data reduction calibration and analysis process and a detailed explanation is given of the calibration process applied to the jupiter data

detection of philippine sea plate motion by very long baseline interferometry the geographical survey institute gsi deployed a mobile very long baseline interferometry vlbi system at an established site in chichijima the biggest island in the bonin islands twice in an interval of two years two sessions were conducted in the experiments each year by connecting the reference base station at kashima space research center of communications research laboratory crl the results from the data of four experiments indicate that the chichijima site moved 7 4 0 8cm in the direction of n67 w in the two years this is the first successful direct measurement of the motion of philippine sea plate phs by any method our result is consistent with the predicted rigid motion of phs from the newest plate velocity model nuvel 1

dislocation model for aseismic crustal deformation at hollister california geodetic observations at many active plate margins reveal relatively steady aseismic motion during the time between major earthquakes we model the aseismic motion by the relative motion between several blocks that suffer frictional resistance in the upper crust frictional drag is represented by uniform dislocation on a fault surface we assume that friction occurs only on the upper brittle zone of each block boundary and that frictionless sliding occurs below this zone using a bayesian inversion procedure we invert geodetic data to determine the parameters of the block and dislocation model parameters to be estimated include the two horizontal components of velocity for each block and the dislocation rate dip angle slip angle and width of each rectangular fault patch for hollister we assume five blocks and nine rectangular fault patches rates of length change on 92 lines observed by trilateration make up the data triangulation leveling very long baseline interferometry satellite ranging and global positioning system data can also be easily included in our model our inversion procedure uses prior estimates of all block and fault parameters based on geological and seismological data the block parameters are estimated from geological observations of fault displacement rates while the widths of the fault patches are estimated from earthquake hypocentral depths we choose prior estimates of the dislocation rate to match observed creep rates the estimated block motion is well resolved by the geodetic data and agrees well with the geological estimates this suggests that the block motion is steady on time scales from 10 years to 1 m y the net motion across the san andreas calaveras fault system is 38 3 mm yr oriented s38 e thus some additional displacement possibly offshore is needed to match the rate of 56 mm yr predicted by plate tectonic models the depth of the transition from frictional to free sliding varies considerably from 0 4 km on the southern calaveras to 11 km on the central san andreas fault two segments of the san andreas north of 36 50 and south of 36 40 have the greatest potential for moderate to large earthquakes

the small inner satellites of saturn shapes structures and some implications abstract properties of the small inner satellites of saturn are updated using final cassini image data the equatorial ridges on pan and atlas are morphologically structurally and gravitationally distinct from their cores and represent distinct additions to rather than modifications of the precursor bodies exposures of lineated substrates on pandora and epimetheus show a relationship between regolith grooves and structures in underlying bedrock structures exposed on epimetheus suggest formation at depth including filling or annealing of fractures these structures and sharp bedrock regolith boundaries indicate a history far more complex than simple rubble pile assembly these exposures of bedrock also indicate past removal of the expected regolith from large fractions of these object s surfaces late in their cratering records

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

nature distribution and origin of co2 on enceladus abstract we present the first map of co2 at the surface of enceladus using data obtained by the cassini visible infrared mapping spectrometer vims in order to measure the weak and narrow co2 absorption band depths around 4 26 m we improved 1 the calibration of vims spectra 2 the calculation of geographic coordinates and 3 the projection techniques we averaged multiple observations of a given area to obtain a signal to noise ratio high enough to map the co2 abundances co2 is reliably detected mostly in the south polar region this region includes active faults tiger stripes the highest observed surface temperatures and locations of active plume eruptions the occurrence here of co2 is consistent with an endogenic origin controlled by tectonics both pure co2 ice and complexed co2 are detected from the positions of absorption bands between 4 27 and 4 24 m the highest concentrations of co2 are between the main active faults of the south polar region where the surface temperature is low pure co2 ice deposits at the surface of enceladus are best modeled by the formation of gas pockets below the icy crust and above the surface of the internal ocean these pockets eventually release cold co2 gas 70 to 119 k at low velocity seeping between the tiger stripes matson et al 2018 icarus 302 18 26 co2 clathrate hydrates may form in the ocean and may be subsequently released when a co2 gas pocket blows out and erupts other mechanisms may contribute to reinforcing the anti correlation of the co2 distribution of any type with respect to the location of the tiger stripes such as successive sublimation of co2 and condensation on colder areas and partial frost cover by h2o releases from plume eruptions

saturn s icy satellites investigated by cassini vims ii results at the end of nominal mission abstract we report the detailed analysis of the spectrophotometric properties of saturn s icy satellites as derived by full disk observations obtained by visual and infrared mapping spectrometer vims experiment aboard cassini in this paper we have extended the coverage until the end of the cassini s nominal mission june 1st 2008 while a previous paper filacchione g and 28 colleagues 2007 icarus 186 259 290 hereby referred to as paper i reported the preliminary results of this study during the four years of nominal mission vims has observed the entire population of saturn s icy satellites allowing us to make a comparative analysis of the vis nir spectral properties of the major satellites mimas enceladus tethys dione rhea hyperion iapetus and irregular moons atlas prometheus pandora janus epimetheus telesto calypso phoebe the results we discuss here are derived from the entire dataset available at june 2008 which consists of 1417 full disk observations acquired from a variety of distances and inclinations from the equatorial plane with different phase angles and hemispheric coverage the most important spectrophotometric indicators as defined in paper i i f continua at 0 55 m 1 822 m and 3 547 m visible spectral slopes water and carbon dioxide bands depths and positions are calculated for each observation in order to investigate the disk integrated composition of the satellites the distribution of water ice respect to contaminants abundances and typical regolith grain properties these quantities vary from the almost pure water ice surfaces of enceladus and calypso to the organic and carbon dioxide rich hyperion iapetus and phoebe janus visible colors are intermediate between these two classes having a slightly positive spectral slope these results could help to decipher the origins and evolutionary history of the minor moons of the saturn s system we introduce a polar representation of the spectrophotometric parameters as function of the solar phase angle along radial distance and of the effective longitude interval illuminated by the sun and covered by vims during the observation in azimuth to better investigate the spatial distribution of the spectrophotometric quantities across the regular satellites hemispheres finally we report the observed spectral positions of the 4 26 m band of the carbon dioxide present in the surface material of three outermost moons hyperion iapetus and phoebe

3 d finite element modelling of deformation and stress associated with faulting effect of inhomogeneous crustal structures summary modelling of deformation and stress caused by earthquake faulting or fault motion based on a homogeneous elastic half space model does not include crustal rigidity layering and lateral variations geological data and seismic surveys indicate that the crust is elastically inhomogeneous and that rigidity layering and heterogeneities are likely to affect the magnitude and pattern of deformation and stress we use the finite element method fem to investigate deformation and stress generated by strike slip tensile and thrust faulting considering rigidity layering in the crust for a fault with a dimension of 25 10 km and a slip value of 0 5 m cutting through the top 10 km of the crust the deformation and stress change associated with the three modes of faulting are calculated for an island arc crustal structure represented by three models of rigidity layering the results indicate i the maximum effect in horizontal displacements due to crustal layering for the investigated models is 19 7 mm and 28 8 mm for strike slip and tensile faulting respectively for thrust faulting the effect is up to 58 3 mm this remarkable effect is due to the offset of layers by thrust faulting which dynamically changes the crustal structure both horizontally and vertically ii the maximum effect in vertical deformation due to crustal rigidity layering for strike slip and tensile faulting is 5 mm in contrast the effect for thrusting is 30 3 mm iii the effect in the shear stress change at a depth of 7 5 km for the different styles of faulting ranges from 0 02 mpa to 0 10 mpa an additional modelling analysis of subduction thrusting at the japan trench with a detailed structural model based on seismic surveys further confirms the significant distortion caused by a homogeneous model that ignores crustal structural information overall the effect of crustal rigidity layering is at least 20 per cent for surface deformation and 15 per cent for stress changes at depth in light of the present accuracy of global positioning system gps observations 2 mm and the estimate of stress change required for earthquake hazard analysis ca 0 01 mpa the results from the numerical experiments indicate that crust inhomogeneity rigidity layering and lateral variations should be included in any quantitative models of faulting

distribution of icy particles across enceladus surface as derived from cassini vims measurements abstract the surface of enceladus consists almost completely of water ice as the band depths of water ice absorptions are sensitive to the size of particles absorptions can be used to map variations of icy particles across the surface the visual and infrared mapping spectrometer vims observed enceladus with a high spatial resolution during three cassini flybys in 2005 orbits en 003 en 004 and en 011 based on these data we measured the band depths of water ice absorptions at 1 04 1 25 1 5 and 2 m these band depths were compared to water ice models that represent theoretically calculated reflectance spectra for a range of particle diameters between 2 m and 1 mm the agreement between the experimental vims and model values supports the assumption that pure water ice characterizes the surface of enceladus and therefore that variations in band depth correspond to variations in water ice particle diameters our measurements show that the particle diameter of water ice increases toward younger tectonically altered surface units with the largest particles exposed in relatively fresh surface material the smallest particles were generally found in old densely cratered terrains the largest particles 0 2 mm are concentrated in the so called tiger stripes at the south pole in general the particle diameters are strongly correlated with geologic features and surface ages indicating a stratigraphic evolution of the surface that is caused by cryovolcanic resurfacing and impact gardening

western nankai trough seismogenic zone results from a wide angle ocean bottom seismic survey the nankai trough southwestern japan is recognized as a vigorous seismogenic zone with well studied historic earthquakes this paper presents results of a wide angle ocean bottom seismographs obs study at the western nankai trough seismogenic zone the obs data used were acquired on a profile 250 km long across the presumed coseismic slip zone of the 1946 nankaido earthquake ms 8 2 the main purpose of the seismic study is to obtain an entire crustal cross section of the seismogenic zone for the 1946 earthquake the crustal model is characterized by a gentle sloping of subducting oceanic crust and thick overlying sedimentary wedge p wave seismic velocities of the subducting oceanic crust show normal oceanic crustal velocities vp 5 0 5 6 km s and 6 6 6 8 km s in oceanic layers 2 and 3 respectively the maximum thickness of the sedimentary wedge is 9 km at 70 km from the trough axis with vp 3 4 4 6 km s in the deeper part the subducting oceanic crust traced down to 25 km depth shows that the subduction angle becomes steeper landward 3 2 and 7 2 at 0 50 km and 50 100 km from the trough axis respectively the oceanic crust is smooth to the hypocenter zone down to 40 km depth beneath shikoku island our crustal model shows that the downdip limit of the coseismic slip area does not extend to the deep end of the oceanic crust island arc crust contact zone even though there is large uncertainty about the seaward limit of the coseismic slip zone the crustal model clearly indicates that the updip limit of the coseismic slip zone extends beneath the young accretionary prism

active shortening of the cascadia forearc and implications for seismic hazards of the puget lowland 1 margin parallel shortening of the cascadia forearc is a consequence of oblique subduction of the juan de fuca plate beneath north america strike slip thrust and oblique crustal faults beneath the densely populated puget lowland accommodate much of this north south compression resulting in large crustal earthquakes to better understand this forearc deformation and improve earthquake hazard assessment we here use seismic reflection surveys coastal exposures of pleistocene strata potential field data and airborne laser swath mapping to document and interpret a significant structural boundary near the city of tacoma this boundary is a complex structural zone characterized by two distinct segments the northwest trending eastern segment extending from tacoma to carr inlet is formed by the broad 11 5 km southwest dipping 11 20 rosedale monocline this monocline raises crescent formation basement about 2 5 km resulting in a moderate gravity gradient we interpret the rosedale monocline as a fault bend fold forming above a deep thrust fault within the rosedale monocline inferred quaternary strata thin northward and form a growth triangle that is 4 1 to 6 6 km wide at its base suggesting 2 3 mm yr of slip on the underlying thrust the western section of the 40 km long north dipping tacoma fault extending from hood canal to carr inlet forms the western segment of the tacoma basin margin structural relief on this portion of the basin margin may be several kilometers resulting in steep gravity and aeromagnetic anomalies quaternary structural relief along the tacoma fault is as much as 350 400 m indicating a minimum slip rate of about 0 2 mm yr the inferred eastern section of the tacoma fault east of carr inlet crosses the southern part of the seattle uplift has variable geometry along strike and diminished structural relief the tacoma fault is regarded as a north dipping backthrust to the seattle fault so that slip on a master thrust fault at depth could result in movement on the seattle fault the tacoma fault or both

robust and exploratory analysis of active mesoscale tectonic zones in japan utilizing the nationwide gps array abstract a monitoring gps array recently developed in japan can yield nationwide maps of active inland tectonic zones atzs on a mesoscale approximately 70 to several hundred kilometers in lateral extent but it has been difficult to characterize atzs in japan as they are in fact operational on multiple scales and our efforts are often hindered by various irregularities in the data the key to overcoming these problems would be to gain an insight into the available data before any precise kinematic modeling is performed with indefinite assumptions in this study horizontal velocity fields deduced from the nationwide gps array were treated with a set of techniques in robust smoothing and exploratory data analysis that brought out exceptionally powerful mesoscale atzs and made them easier to characterize the resolved atzs were then retrospectively monitored to study their regional and temporal variations using a set of approx 840 observation stations about 30 km apart for a 4 year series of fixed observation time intervals 810 days each the smoothing operation involved three steps 1 imputation of the velocity fields for the purpose of anti aliasing 2 robust smoothing of the velocity fields with the median operative and 3 visualization of deformation rate distributions in several coordinate independent parameters and post filtering the geometrical resolvability of mesoscale atzs was confirmed by calibrating the smoothing scheme against synthetic tectonic boundary models before it was applied to the case study in japan atzs in japan which are essentially visible as systematic deviations in the velocity fields on the international terrestrial reference frame itrf and as strain rate anomalies were highlighted sharply along some known tectonic zones chains of active volcanoes and areas above low seismic velocity anomalies in the crust and upper mantle all of which generally paralleled the offshore trench axes the geometrical agreements among the mapped atzs and the physical anomalies in the crust are presumably due to their common structural weakness on the mesoscale in the four main islands of japan all but 30 40 of the strain rate anomalies persisted during the entire 6 years of the case study period while the rest sporadically appeared or disappeared in a period from several months to a few years the transient shifts in the deformation rates were remarkably synchronous with some nearby major tectonic episodes large earthquakes and slow events differential plate coupling strengths along the subduction zones can also be inferred from the persistent pattern of rotational strain rate anomalies forming clockwise and counterclockwise pairs along the pacific our empirical observations suggest that the first order features of interseismic crustal deformations in japan can be characterized as collateral processes behaving in response to fluctuations of the tectonic stresses on multiple scales likely influenced by changes of plate coupling strengths on the contiguous subduction faults

cassini s geological and compositional view of tethys abstract the saturnian satellite tethys exhibits geological and spectral properties whose appearance nature and spatial distribution partly mirror those identified on the neighboring satellites dione and rhea or fit to the picture how spectral surface properties are expected to change from one satellite to the other within the inner saturnian system however we also identified spectral variations that are unique in the saturnian system whereas geologically young surface features are characterized by pure h2o ice composition with relatively large particles which match the particle sizes measured for fresh surface features also on dione and rhea geologically old weathered regions are dominated by submicron sized ice particles our investigations confirm that the odysseus impact event did not cause the formation of tethys extended graben system ithaca chasma on the contrary odysseus might be responsible for the n s trending icy bands that mark tethys surface in the center of its leading and trailing hemisphere

factors affecting seismic moment release rates in subduction zones the amount of shallow seismic activity in subduction zones varies greatly from region to region we quantify this seismicity by calculating seismic moment release rates and seismic slip rates for 24 subduction zones to calculate the moment release we sum the seismic moment for all interplate thrust type events with surface wave magnitude ms 7 0 occurring from 1904 to 1980 we present a time history plot of the seismic moment release for each subduction zone these exhibit the differences in the seismic release patterns for subduction zones where the time window of our study is not representative the total moment release is corrected using information on repeat times the moment release rates are compared with various subduction parameters in order to determine which factors influence the degree of coupling these parameters include the age of the subducting lithosphere absolute velocities of the upper and subducting plates convergence velocity and length maximum depth and dip of the wadati benioff zone the moment release rate decreases as the age of the subducting lithosphere increases when the zones belonging to a single subducting plate are considered this age versus moment release relation is consistent for the zones in which the pacific cocos philippine sea and indian plates are subducting the moment release rates for the subduction zones in which the pacific plate is subducting are much higher than for zones of other plates with similar age the age versus moment release relation holds among the zones which belong to one subducting plate however zones with similar ages but belonging to different plates do not have the same moment release rates this suggests that within a single plate the age is the dominating factor affecting the strength of seismic coupling but that each plate as a whole has a characteristic moment release budget zones with retreating upper plates tend to have lower moment release rates the moment release rate does not increase with convergence velocity no simple relationship was found between these two parameters the moment release rate depends most clearly on the age of the subducting lithosphere and the absolute velocity of the upper plate these are the two independent subduction zone parameters among the variables considered the other variables depend on these two parameters

impact of arc continent collision on the conditions of burial and exhumation of uhp lt rocks experimental and numerical modelling abstract a 2 d physical and finite element numerical modelling of arc continent collision was performed to study the deformation and failure of the overriding lithosphere the experimental technique allowed us to model the whole subduction collision process from oceanic subduction to deep subduction of the continental crust with the numerical approach we have modelled the deformation of the overriding plate only through initial stages of its failure and studied the influence of different parameters on this process the results obtained by both techniques are coherent and mutually complementary they show that the failure of the overriding plate is physically quite plausible or even inevitable during subduction the conditions for such a failure the weakening of this plate are prepared during oceanic subduction the weakening occurs due to the interaction between the subducting lithosphere and the asthenosphere in the mantle corner between the two plates and due to back arc spreading in oceanic subduction zones with a compressional regime no back arc opening thick and strong back arc lithosphere the weakest zone is volcanic arc area when weakening becomes sufficient during subduction the lithosphere fails in this area the failure occurs along a fault dipping under the arc in either of two possible directions and results either in subduction reversal or subduction of the fore arc almost half of the presently active subduction zones are characterised by a tensional subduction regime with back arc spreading in such subduction zones the weakest place is not the volcanic arc but the back arc spreading centre when a subduction regime changes from tensional to compressional failure occurs in the vicinity of the extinct spreading centre this process can occur during oceanic subduction again along either a trench vergent or trenchward dipping fault but the formation of a trench verging fault is most likely in this latter case which is a principal subject of our study the failure is followed by partial subduction of the arc plate complete subduction occurs during arc continent collision subduction of the continental margin when tectonic compression of the lithosphere increases rapidly and becomes sufficient to push the arc plate into the mantle the arc itself can be subducted completely or be partially or completely scraped off and accreted a deeply subducted material including continental margin is preserved at relatively low temperatures between the lithospheric mantle and the cold subducted arc plate to about 150 km depth subduction of the arc plate is a major phenomenon which affects all processes associated with continental subduction from deep burial and hp lt metamorphism to exhumation of subducted material does this process occur in nature future investigations will allow us to answer this question in this paper we analyse the conditions of emplacement of a very young oceanic lithosphere samail ophiolite on the continental crust in oman in the late cretaceous and argue that this lithosphere formed in a back arc basin it reached and overthrust the arabian continent after complete subduction of the arc plate

the equatorial ridges of pan and atlas terminal accretionary ornaments in the outer regions of saturn s main rings strong tidal forces balance gravitational accretion processes thus unusual phenomena may be expected there the cassini spacecraft has recently revealed the strange flying saucer shape of two small satellites pan and atlas located in this region showing prominent equatorial ridges the accretion of ring particles onto the equatorial surfaces of already formed bodies embedded in the rings may explain the formation of the ridges this ridge formation process is in good agreement with detailed cassini images showing differences between rough polar and smooth equatorial terrains we propose that pan and atlas ridges are kilometers thick ring particle piles formed after the satellites themselves and after the flattening of the rings but before the complete depletion of ring material from their surroundings

secular crustal deformation and interplate coupling of the japanese islands as deduced from continuous gps array 1996 2001 abstract data from the nation wide gps continuous tracking network that has been operated by the geographical survey institute of japan since april 1996 were used to study crustal deformation in the japanese islands we first extracted site coordinate from daily sinex files for the period from april 1 1996 to february 24 2001 since raw time series of station coordinates include coseismic and postseismic displacements as well as seasonal variation we model each time series as a combination of linear and trigonometric functions and jumps for episodic events estimated velocities were converted into a kinematic reference frame heki k 1996 horizontal and vertical crustal movements from three dimensional very long baseline interferometry kinematic reference frame implication for reversal timescale revision j geophys res 101 3187 3198 to discuss the crustal deformation relative to the stable interior of the eurasian plate a least squares prediction technique has been used to segregate the signal and noise in horizontal as well as vertical velocities estimated horizontal signals horizontal displacement rates were then differentiated in space to calculate principal components of strain dilatations maximum shear strains and principal axes of strain clearly portray tectonic environments of the japanese islands on the other hand the interseismic vertical deformation field of the japanese islands is derived for the same gps data interval the gps vertical velocities are combined with 31 year tide gage records to estimate absolute vertical velocity the results of vertical deformation show that 1 the existence of clear uplift of about 6 mm yr in shikoku and kii peninsula whereas pattern of subsidence is observed in the coast of kyushu district this might reflect strong coupling between the philippine sea plate and overriding plate at the nankai trough and weak coupling off kyushu 2 no clear vertical deformation pattern exists along the pacific coast of northeastern japan this might be due to the long distance between the plate boundary japan trench and overriding plate where gps sites are located 3 significant uplift is observed in the southwestern part of hokkaido and in northeastern tohoku along the japan sea coast this is possibly due to the viscoelastic rebound of the 1983 japan sea mw 7 7 and the 1993 hokkaido nansei oki mw 7 8 earthquakes and or associated with distributed compression of incipient subduction there we then estimate the elastic deformation of the japanese islands caused by interseismic loading of the pacific and philippine sea subduction plates the elastic models account for most of the observed horizontal velocity field if the subduction movement of the philippine sea plate is 100 locked and if that of the pacific plate is 70 locked however the best fit for vertical velocity ranges from 80 to 100 coupling factor in southwestern japan and only 50 in northeastern japan since horizontal data does not permit the separation of rigid plate motion and interplate coupling because horizontal velocities include both contributions we used the vertical velocities to discriminate between them so we can say there is strong interplate coupling 80 100 over the nankaido subduction zone whereas it is about 50 only over the kurile japan trench

spectroscopic classification of icy satellites of saturn ii identification of terrain units on rhea abstract dione is one of the largest and densest icy satellites of saturn its surface shows a marked asymmetry between its leading and trailing hemispheres the leading side being brighter than the trailing side which shows regions mantled by a dark veneer whose origin is likely exogenic in order to identify different terrain units we applied the spectral angle mapper sam classification technique to dione s hyperspectral images acquired by the visual and infrared mapping spectrometer vims onboard the cassini orbiter in the infrared range 0 88 5 12 m on a relatively limited portion of the surface of dione we first identified nine spectral endmembers corresponding to as many terrain units which mostly distinguish for water ice abundance and ice grain size we then used these endmembers in sam to achieve a comprehensive classification of the entire surface the analysis of the infrared spectra returned by vims shows that different regions of dione have variations in water ice bands depths in average ice grain size and in the concentration of contaminants such as co 2 and hydrocarbons which are clearly connected to morphological and geological structures generally the spectral units that classify optically dark terrains are those showing suppressed water ice bands a finer ice grain size and a higher concentration of carbon dioxide conversely spectral units labeling brighter regions have deeper water ice absorption bands higher albedo and a smaller concentration of contaminants we also considered vims cubes of the small satellite helene one of the two dione s trojan moons and we compared its infrared spectra to those of the spectral units found on dione we observe that the closest match between the spectra of the two satellites occurs for one of the youngest and freshest terrain units on dione the creusa crater region

geodesy by radio interferometry evidence for contemporary plate motion analysis of 211 very long baseline interferometry observing sessions carried out between november 1979 and august 1984 has yielded estimates of the distances between various radio telescopes located in north america and europe the average rate of change of the distances between four radio telescopes in north america haystack observatory massachusetts westford radio telescope massachusetts george r agassiz station texas and owens valley radio observatory california and one in europe onsala space observatory sweden obtained from the analysis of these data is 19 10 mm yr where the 68 confidence interval standard deviation is for the estimate of the rate of change of the haystack onsala baseline length the one determined most accurately from these data this estimate of the standard deviation is dominated by the effects of correlated systematic errors due mostly to errors in the model used for the atmospheric delay which we infer introduces errors in each baseline length estimate of 40 mm standard deviation and 60 days correlation time by contrast the statistical standard deviation is only 2 mm yr the estimated geologic rates of change of these baseline lengths averaged over 106 years are 15 to 17 3 mm yr for the various north american sites to onsala improvements in our model of the atmosphere and continued monitoring of the distances between north american and european telescopes will allow the uncertainty of the rate estimates to be reduced over the next few years to a value small compared to our estimated rate of change of these baseline lengths the use of multiple radio telescopes in europe will allow us also to separate possible local site motions from plate motions

close cassini flybys of saturn s ring moons pan daphnis atlas pandora and epimetheus saturn s main ring system is associated with a set of small moons that are either embedded within it or interact with the rings to alter their shape and composition five close flybys of the moons pan daphnis atlas pandora and epimetheus were performed between december 2016 and april 2017 during the ring grazing orbits of the cassini mission data on the moons morphology structure particle environment and composition were returned along with images in the ultraviolet and thermal infrared the optical properties of the moons surfaces are determined by two competing processes contamination by a red material formed in saturn s main ring system and by accretion of bright icy particles or water vapor from volcanic plumes originating on the planet s moon enceladus

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

interpretations of a middle miocene and late quaternary steady dextral transpression in sw japan and the opening tectonics for the japan sea abstract an internal rotation hypothesis for the deformation of sw japan for middle miocene and recent times is studied rotations are known to have occurred from paleomagnetic data for the earlier case two geodetic flow field estimates as well as another tectonic study suggest that the rotations are also taking place at present a further examination of the geodetic flow models suggests that the rotations contained in these flow models are intrinsic to the deformation of sw japan which occurs in an e w dextral transpressive simultaneous pure and simple shear tectonic regime maps of rotation rates one half of vorticity and shear gradients the n s variation of the e w velocity field constructed from the geodetic flow models resemble one another in pattern the estimates of the directions of the principal strain rates from the geodetic models are on the whole n s contractional and or e w extensional which match the geodetic reference coordinate system used in the adjustment of the geodetic data these observations suggest that the vortical flow contained in the geodetic flow models is a frame independent shear induced vorticity as the material is rotating with respect to the principal directions of the strain rates and that the oblique motion of the philippine sea plate is partitioned between shear and arc normal convergence components the rotation rate is 10 12 ma furthermore the kinematical vorticity number estimates from the geodetic data correlate well with the first order tectonic fabric patterns in sw japan super simple shear deformation for large parts of sw japan where the median tectonic line and other large strike slip faults are found is also indicated in the internal kinematical vorticity number estimates a new model for the formation of the japan sea is proposed extrusion of japan due to the okhotsk eurasia collision this model agrees with the fundamental observations of the early middle miocene deformation in the region the application of an indentation extrusion model to the okhotsk eurasia collision results in a better agreement between the predicted and observed structures and leads to simpler more reasonable and coherent interpretations for the origin and development of the structures compared with the achievements of the previous models the nne trending early middle miocene rifts lying along the continental margin of western hokkaido formed as pull apart basins along a sinistral fault related to the collision of the okhotsk plate which segmented in a left handed sense because the collision was oblique the n s trending rifts and the normal faults found in the back arc domain of the ne honshu arc formed by eastward extrusion under the influence of the mariana type subduction in the japan trench these rift basins were subsequently left laterally displaced by movement along nw trending sinistral strike slip faults the shikoku basin opened from the east toward the west and dextral shear was imparted to the sw margin from the nankai trough leading to clockwise rotations in the middle miocene in sw japan the paleomagnetic rotations are accommodated as fully internal structural rotations in the new model for the origin of the japan sea the current episode of deformation in sw japan began 1 5 million years ago after a hiatus during a 15 5 ma interval and is likely a continuation of the middle miocene style of tectonics

coseismic slip resolution along a plate boundary megathrust the nankai trough southwest japan geodetic survey measurements are used to estimate the coseismic slip distribution in the 1944 tonankai mw 8 1 and 1946 nankaido mw 8 3 earthquakes and to assess quantitatively the degree to which this slip is resolved on the plate boundary megathrust data used include 798 angle changes from triangulation surveys 328 leveling section differences and 5 coseismic tidal gage offsets many of the nominally coseismic triangulation data span 50 years nearly half the earthquake cycle and correction for interseismic deformation using post 1950 observations is applied microseismicity is used to define the configuration of the plate boundary interface and approximate it with a continuous multisegment fault model because the onshore geodetic data have very limited resolving power for offshore fault segments offshore coseismic slip was constrained by satake s 1993 estimation based on tsunami data the majority of the coseismic slip occurs between 15 and 25 km depth although resolution declines toward the trench axis it is sufficiently good to define two distinct high slip regions one off southeastern shikoku island 11 m maximum and the other offshore of kii peninsula 3 m maximum the slip magnitude off southeastern shikoku coupled with the plate convergence rate would imply an recurrence interval of about 270 years much longer than the average repeat time of 120 years for historical great earthquakes on the nankai trough however the maximum coseismic slip is sensitive to the assumed fault geometry and slippage on trough parallel splay faults could significantly decrease the maximum slip to about 6 m

magnetic polarity stratigraphy and possible differential tectonic rotation of the miocene pliocene mammal bearing san timoteo badlands southern california abstract the san timoteo badlands consisting of the mt eden beds conformably overlain by the san timoteo beds is a 3000 m thick sequence of nonmarine sediments deposited in a tectonically active region in southern california paleomagnetic samples were collected from 132 sites within these badlands a composite magnetostratigraphic section for this sequence correlates to the mpts from the late part of chron c3an 1n to the early part of chron c2r 2r between about 6 and 2 3 ma the classic late hemphillian late miocene mt eden fossil mammal quarry occurs near the base of the composite section within chron c3r between 5 8 and 5 3 ma although the overall unit mean declinations indicate negligible or slight counterclockwise ccw vertical axis rotation 8 8 4 9 analysis of declination subsets from different parts of the section suggest possible differential small block rotation within the san timoteo badlands prior to 3 5 ma represented by the mt eden beds there is negligible rotation the overlying portion of the san timoteo badlands represented by the lower san timoteo beds dated between 3 5 and 2 3 ma chrons c2an 3n to c2r 2r indicate significant apparent ccw rotation r r of 20 7 5 2 these data suggest decoupling of the upper part of the san timoteo badlands and independent ccw vertical axis rotation relative to the lower part of this sequence

interseismic horizontal deformation in northern honshu and its relationship with the subduction of the pacific plate in the japan trench we investigate the origin of the geodetically observed interseismic horizontal deformation in northern honshu by comparing shear strain rates principal strain rates and velocity fields determined from geodetic data with those calculated from the elastic dislocation models involving interplate motion at the japan trench the agreement between the observed and predicted directions of the principal strain axes indicates that the geodetic strain field in northern honshu is primarily elastic strain transmitted from the japan trench in order to match the strain rate tensors and velocity magnitudes obtained from the geodetic data the dislocation model requires that 35 to 60 of the nuvel1 a pacific north american plate motion is locked at the plate interface along the japan trench the down dip depth limit of the locked zone is inferred to be 55 km which is consistent with the seismic data in the japan trench

the relationship between the instantaneous velocity field and the rate of moment release in the lithosphere summary instantaneous velocity gradients within the continental lithosphere are often related to the tectonic driving forces this relationship is direct if the forces are secular as for the case of loading of a locked section of a subduction interface by the downgoing plate if the forces are static as for the case of lateral variations in gravitational potential energy then velocity gradients can be produced only if the lithosphere has on average zero strength the static force model may be related to the long term velocity field but not the instantaneous velocity field typically measured geodetically over a period of several years because over short time intervals the upper lithosphere behaves elastically in order to describe both the short and long term behaviour of an elastic lithosphere viscoelastic asthenosphere system in a selfconsistent manner i construct a deformation model termed the expected interseismic velocity eiv model assuming that the lithosphere is populated with faults that rupture continually each with a definite mean recurrence time and that the earth is well approximated as a linear elastic viscoelastic coupled system i derive a simple relationship between the instantaneous velocity field and the average rate of moment release in the lithosphere examples with synthetic fault networks demonstrate that velocity gradients in actively deforming regions may to a large extent be the product of compounded viscoelastic relaxation from past earthquakes on hundreds of faults distributed over large 10 6 km 2 areas

is northern honshu a microplate abstract seismic slip vectors along the japan trench the eastern margin of the japan sea and the sagami trough are compared with global relative plate motions rm2 minster and jordan 1978 to test a new hypothesis that northern honshu japan is part of the north american plate this hypothesis also claims that the eastern margin of the japan sea is a nascent convergent plate boundary kobayashi 1983 nakamura 1983 seismic slip vectors along the japan trench are more parallel to the direction of the pacific north american relative motion than that of the pacific eurasian relative motion however the difference in calculated relative motions is too small avoid to the possibility that a systematic bias in seismic slip vectors due to anomalous velocity structure beneath island arcs causes this apparent coincidence seismic slip vectors and rates of shortening along the eastern margin of the japan sea for the past 400 years are also consistent with the relative motion between the north american and eurasian plates calculated there seismic slip vectors and horizontal crustal strain patterns revealed by geodetic surveys in south kanto beneath which the philippine sea plate is subducting indicate two major directions one is the relative motion between the north american and philippine sea plates and the other that between the eurasian and philippine sea plates one possible interpretation of this is that the eastern margin of the japan sea may be in an embryonic stage of plate convergence and the jump of the north american eurasian plate boundary from sakhalin central hokkaido to the eastern margin of the japan sea has not yet been accomplished in this case northern honshu is a microplate which does not have a driving force itself and its motion is affected by the surrounding major plates behaving as part of either the eurasian or north american plate another possibility is that the seismic slip vectors and crustal deformations in south kanto do not correctly represent the relative motion between plates but represent the stresses due to non rigid behaviors of part of northern honshu

deformation of an island arc rates of moment release and crustal shortening in intraplate japan determined from seismicity and quaternary fault data the historical record of large m 6 9 earthquakes and geologically determined rates of slip on quaternary faults in intraplate japan honshu and shikoku are used to estimate the average rate of seismic moment release m for the last 400 years and during the late quaternary respectively values of m estimated from the two data sets are similar in regions where seismic activity is concentrated on land we interpret this observation to suggest that m in intraplate japan has been constant during the late quaternary and is relatively free from secular variation when averaged over periods of several hundreds of years m in shikoku may be attributed almost solely to right lateral slip of the median tectonic line mtl the easterly strike of the mtl is consistent with a compressive stress field that trends northwest crustal shortening of the izu peninsula taken up on a set of strike slip faults that show north by northwest compression is 1 mm yr northeast honshu is characterized by a set of reverse type faults that trend northerly conversion of m in northeast japan to strain rates suggests that about 5 of the relative plate motion between japan and the pacific plate 9 7 cm yr is accommodated as a permanent east west shortening 5 mm yr of northeast honshu the predominant deformation in central and western honshu takes place as slip on a conjugate system of strike slip faults that strike northeast and southeast and show right lateral and left lateral motion respectively crustal shortening resulting from slip on faults in central and western honshu is 5 and 0 5 mm yr respectively in an easterly direction central and western honshu are in closest proximity to the nankai trough and hence the stress field in these regions cannot simply be attributed to the accommodation of the relative northwesterly convergence of the philippine sea plate the northward impingement of the izu peninsula into honshu may influence stresses in central and western japan but a conclusive explanation of the stress field in central and western honshu remains an enigma

structural control on late miocene to quaternary volcanism in the ne honshu arc japan 1 volcanological and structural field data are used to define the tectonic control on the n s volcanic arc of ne honshu japan since late miocene during late miocene pliocene bimodal products were mainly erupted from along arc and ne sw aligned and elongated calderas the deformation pattern mostly consisted of n s dextral faults and subordinate ne sw extensional structures produced by ne sw compression this pattern because of the indentation of the kuril sliver is similar to that of oblique convergence settings magma rose and extruded along ne sw areas of localized extension created by the dextral faults these extensional areas were uncoupled with regard to those e w trending inferred to have focused the rise of melts from the subducting slab in the mantle during quaternary a larger amount of andesite was mainly erupted from along arc and e w aligned and elongated stratovolcanoes the deformation pattern mostly consisted of n s thrust faults and subordinate e w extensional structures produced by e w compression resulting from orthogonal convergence due to the variation in the absolute motion of the pacific plate the e w extensional structures are the shallowest expression of e w trending hot mantle fingers suggesting mantle crust coupling for the rise of magma such a coupling ensures 1 higher extrusion and 2 mixing between a deeper mafic and a shallower felsic magma generating the andesites the significantly larger volumes ma 1 200 km 1 of length of the arc of magma erupted during quaternary show that pure convergence conditions do not necessarily hinder the rise and extrusion of magma

the inner small satellites of saturn a variety of worlds more than a dozen small 150 km mean radius satellites occupy distinct dynamical positions extending from within saturn s classical rings to the orbit of dione the cassini mission has gradually accumulated image and spectral coverage of these objects to the point where some generalizations on surface morphology may be made objects in different dynamical niches have different surface morphologies satellites within the main rings display equatorial ridges the f ring shepherding satellites show structural forms and heavily cratered surfaces the co orbitals janus and epimetheus are the most lunar like of the small satellites satellites occupying libration zones trojan satellites have deep covering of debris subject to downslope transport small satellites embedded in ring arcs are distinctively smooth ellipsoids that are unique among small well observed solar system bodies and are probably relaxed effectively fluid equilibrium shapes indicative of mean densities of about 300 kg m 3

surface composition of hyperion hyperion saturn s eighth largest icy satellite is a body of irregular shape in a state of chaotic rotation the surface is segregated into two distinct units a spatially dominant high albedo unit having the strong signature of h2o ice contrasts with a unit that is about a factor of four lower in albedo and is found mostly in the bottoms of cup like craters here we report observations of hyperion s surface in the ultraviolet and near infrared spectral regions with two optical remote sensing instruments on the cassini spacecraft at closest approach during a fly by on 25 26 september 2005 the close fly by afforded us the opportunity to obtain separate reflectance spectra of the high and low albedo surface components the low albedo material has spectral similarities and compositional signatures that link it with the surface of phoebe and a hemisphere wide superficial coating on iapetus

crustal deformation and stress localization in kanto tokai central japan revealed by gps summary horizontal deformation associated with plate interaction in the kanto tokai district central japan has been determined using the japanese permanent global positioning system gps array with an accuracy of better than 2 5 mm yr 1 previous analysis of the gps observations mainly focused on the pattern of deformation or strain and did not attempt to assess stress change associated with plate subduction in this study using the gps observations and the geometry of subducting slabs as constraints we constructed a 3 d kinematic model to simulate the subduction of the philippine sea plate at the suruga and sagami troughs and the pacific plate at the japan trench the model incorporating the effects of major plate driving forces ridge push slab pull and drag force associated with plate subduction provides an overall fit to the horizontal deformation observed by gps during 1996 2001 in the kanto tokai region the horizontal motion of the philippine sea plate is estimated to be 41 5m m yr 1 60 5 nw consistent with that ca 43 50 mm yr 1 inferred from earthquake slip vectors and geological data the horizontal motion of the pacific plate is estimated to be 78 6m m yr 1 84 5 nw close to that ca 73 79 mm yr 1 deduced from earthquake slip vectors after extracting the regional deformation associated with subduction of the philippine sea and pacific plates from the gps observations two types of motion trends are revealed for the northern part of the kanto tokai region the southeastward motion of the gps stations revealed by the residual displacements in northern tokai indicates a possible resistance force from the north in northern kanto the west southwestward residual motion of the gps stations indicates the motion of the north american plate relative to the eurasian plate the distinct boundary between these two different types of motion trends provides strong support for the presence of the north american plate in the region which demonstrates that the model has delineated the main characteristics of plate interaction further a stress analysis indicates that stress is accumulating on the suruga trough at a rate of approximately 0 7 bar yr 1 at a depth of 15 km our results indicate that the pattern of stress localization is mainly controlled by the kinematic characteristics of the subducted slabs geometry and slip distribution and the persistent stress concentration is responsible for repeated large interplate earthquakes in the region

crustal velocity field of southwest japan subduction and arc arc collision we investigate crustal deformation in southwest japan over a 3 year period revealed by a permanent dense global positioning system gps array southwest japan is a part of the amurian plate a microplate moving about 10 mm yr toward the east with respect to the eurasian plate it overrides the philippine sea plate at the nankai trough and collides with the northeast japan arc in the central part of japan in this paper we first derive gps site velocities relative to the stable part of the amurian plate in order to isolate signals of crustal deformation caused by the subduction and or the collision the velocity field has a conspicuous feature indicating the interseismic elastic loading by the philippine sea plate slab at the nankai trough characterized by the northwestward movements of points throughout the studied area their amplitudes are the largest at the pacific coast and decay toward the japan sea coast with a subtle systematic shift of azimuths a model assuming an elastic half space the convergence rate at the nankai trough based on a refined euler vector and the strength of the coupling inferred from a thermal model could explain the velocity field in the western part of the studied area to a large extent those in the eastern part systematically deviate from them and the residual components there show east west shortening and north south extension this may represent crustal thickening and trenchward extrusion of crustal blocks caused by the collision between southwest and northeast japan this suggests that the collision between southwest and northeast japan gives rise to not only crustal thickening but also trenchward extrusion of crustal block a velocity contrast was found across the median tectonic line the largest inland active fault in japan but the current permanent gps network is not dense enough for us to discuss its coupling depth

zenisu ridge a deep intraoceanic thrust related to subduction off southwest japan abstract during the french japanese kaiko project seabeam seismic and submersible observations were made in the eastern part of the nankai subduction zone close to the area of collision between the izu bonin island arc and the japan margin the most prominent feature is the zenisu ridge an elongated relief of the philippine sea plate running parallel to the trench magnetic anomalies indicate that the crust of the zenisu ridge is a part of the shikoku oceanic basin formed in the early miocene 23 ma ago and presumably uplifted at a later stage structural analysis of seismic data and diving observations lead us to interpret the superficial structure as being due to compressive tectonics mapping the acoustic basement reveals that the southeastern flank of the ridge is bounded by a double thrust both segments being of equal magnitude vertical offset about 1 to 1 5 km geophysical data support the hypothesis of a main thrust cutting through most of the lithosphere and flattening at depth the overall structure of the surrounding area reveals a compressive deformation zone widening toward the east the magnitude of the compressive deformation decreasing westward as well as southward of the zenisu ridge

spatial variations in 3he 4he ratios along a high strain rate zone central japan abstract a linear zone with high strain rates along the japan sea coast the niigata kobe tectonic zone nktz is considered to be associated with rheological heterogeneities in the lower crust and or upper mantle helium isotope variations along the nktz reveal a close association with the geophysical evidence for rheological heterogeneities in the crust and mantle in the southern nktz the 3 he 4 he ratios lower than 3 4 ra ra denotes the atmospheric 3 he 4 he ratio of 1 4 10 6 could be interpreted as a two component mixture of helium stored in aqueous fluids driven off the subducting oceanic crust and radiogenic crustal helium higher 3 he 4 he ratios are observed in the central nktz where quaternary volcanoes and high temperature hot springs are concentrated suggesting that the 3 he emanation manifest in the central nktz results from the effective transfer of mantle helium by intrusion and degassing of mantle derived magma in the crust in the northern nktz where two large inland earthquakes occurred recently there appears to be many samples with 3 he 4 he ratios significantly higher than those observed in the fore arc side of northeast japan a plausible source of mantle helium could be attributed to upward mobilization of aqueous fluids generated by dehydration of the subducting pacific plate slab

saturn s icy satellites investigated by cassini vims iv daytime temperature maps abstract the spectral position of the 3 6 m continuum peak measured on cassini vims i f spectra is used as a marker to infer the temperature of the regolith particles covering the surfaces of saturn s icy satellites this feature is characterizing the crystalline water ice spectrum which is the dominant compositional endmember of the satellites surfaces laboratory measurements indicate that the position of the 3 6 m peak of pure water ice is temperature dependent shifting towards shorter wavelengths when the sample is cooled from about 3 65 m at t 123 k to about 3 55 m at t 88 k a similar method was already applied to vims saturn s rings mosaics to retrieve ring particles temperature filacchione g ciarniello m capaccioni f et al 2014 icarus 241 45 65 we report here about the daytime temperature variations observed on the icy satellites as derived from three different vims observation types a a sample of 240 disk integrated i f observations of saturn s regular satellites collected by vims during years 2004 2011 with solar phase in the 20 40 range corresponding to late morning early afternoon local times this dataset is suitable to exploit the temperature variations at hemispherical scale resulting in average temperature t t 88 k for enceladus t t 98 118 k for dione t 108 128 k for rhea t 118 128 k for hyperion t 128 148 and t 168 k for iapetus trailing and leading hemispheres respectively a typical 5 k uncertainty is associated to the temperature retrieval on tethys and dione for which observations on both leading and trailing hemispheres are available in average daytime temperatures higher of about 10 k on the trailing than on the leading hemisphere are inferred b satellites disk resolved observations taken at 20 40 km pixel 1 resolution are suitable to map daytime temperature variations across surfaces features such as enceladus tiger stripes and tethys equatorial dark lens these datasets allow to disentangle solar illumination conditions from temperature distribution when observing surface s features with strong thermal contrast c daytime average maps covering large regions of the surfaces are used to compare the inferred temperature with geomorphological features impact craters chasmatae equatorial radiation lenses and active areas and albedo variations temperature maps are built by mining the complete vims dataset collected in years 2004 2009 pre equinox and in 2009 2012 post equinox by selecting pixels with max 150 km pixel 1 resolution vims derived temperature maps allow to identify thermal anomalies across the equatorial lens of mimas and tethys a temperature t 115k is measured above enceladus damascus and alexandria sulci in the south pole region vims has the sensitivity to follow seasonal temperature changes on tethys dione and rhea higher temperature are measured above the south hemisphere during pre equinox and above the north hemisphere during post equinox epochs the measured temperature distribution appears correlated with surface albedo features in fact temperature increases on low albedo units located on tethys dione and rhea trailing hemispheres the thermal anomaly region on rhea s inktomi crater detected by cirs howett c j a spencer j r hurford t et al 2014 icarus 241 239 247 is confirmed by vims this area appears colder with respect to surrounding terrains when observed at the same local solar time

active strike slip faulting and macroscopically nonrigid deformation of volcanic rocks in central japan inferred from a paleomagnetic study abstract detailed paleomagnetic investigation of a pyroclastic flow deposit has clarified the deformation mode around an active fault in central japan the early quaternary nyukawa pyroclastic flow deposit is cut by the active dextral enako fault activity level of the fault is evaluated on the basis of geological and geomorphological surveys then paleomagnetic samples are collected from 22 sites at exposures located on a lineament that is adjoining and parallel to the enako fault stable thermoremanent magnetization trm of the pyroclastic deposit is isolated through progressive thermal and or alternating field demagnetization tests untilted site mean directions of the trms simultaneously acquired during initial cooling indicate significant clockwise vertical axis rotation the lineament was then activated with right lateral motions through the early quaternary together with the late quaternary activities along the adjoining enako fault evaluated by our study the present result exemplifies a migration of active segments within a fault system during the quaternary paleomagnetic directions on the strike slip fault are not concordant with uniform deformation predicted by the model of rotation of rigid blocks aligned on a master fault but suggestive of a periodic deformation as a result of intense fracturing and differential rotation of blocks bounded by nested parallel faults

interplate coupling in southwest japan deduced from inversion analysis of gps data abstract recently the geographical survey institute of japan completed the installation of a gps continuous observation network in japan which has enabled us to investigate real time crustal movements in this study we attempt to obtain spatial distribution of interplate coupling and relative plate motion between subducting and overriding plates in southwest japan using horizontal and vertical deformation rates which were observed at 247 gps observation stations during the period from april 6 1996 to march 20 1998 for this purpose we carried out an inversion analysis of geodetic data incorporating akaike s bayesian information criterion abic as a result strong interplate coupling was found off shikoku and kumanonada regions which corresponds well with the fault regions of the 1946 nankai m 8 1 and the 1944 tonankai m 8 0 earthquakes respectively we also found that interplate coupling becomes weak at depths deeper than about 30 to 40 km beneath the shikoku and kii peninsula the recurrence time of great trench type earthquakes was roughly estimated as 107 years which is consistent with previous research the direction of relative plate motion is oriented n53 w which is close to the direction predicted from the plate motion model on the other hand a large forward slip was found in the hyuganada region off southeast of kyushu since the coseismic displacements associated with the two 1996 hyuganada earthquakes m 6 6 m 6 6 are removed from the gps data this suggests that after slip occurred near the source region and or that kyushu moves southeastward stationarily due to other tectonic forces

seismotectonics of the hida region central honshu japan abstract seismotectonic features of the northern hida region central honshu japan have been investigated in some detail mainly on the basis of the last 6 years of observations of seismicity and focal mechanism of a large number of earthquakes with reference to the geological and tectonic setting and evidence of a large earthquake in the past it was found that high seismicity is concentrated with a remarkably clear lineation but with a relatively low activity in the central section along the atotsugawa fault extending for about 70 km this is one of major quaternary faults in this region the high seismicity with spatially nonuniform distribution may be related to postseismic stress concentration after the 1858 hida earthquake m 7 0 and to heterogeneous fault strength seismicity is also high with belt like extension beneath the hida mountain range which is the highest mountain system in the japan islands the depth distribution of seismicity is clearly bounded at 15 km below the atotsugawa fault and 8 km beneath the hida mountains the local variations can be interpreted as being due to the difference in the brittle ductile transition depth which suggests higher temperature beneath the mountains involving active volcanoes the focal mechanism solutions indicate that the maximum compressive stress is oriented in an ese wnw direction which is more consistent with the direction of motion of the pacific plate relative to the eurasian plate rather than the suggested relative motion between the north america and eurasian plates the magnitude of the shear stress working in this region is estimated to be less than 700 bar

stress transferred by the 1995 mw 6 9 kobe japan shock effect on aftershocks and future earthquake probabilities the kobe earthquake struck at the edge of the densely populated osaka kyoto corridor in southwest japan we investigate how the earthquake transferred stress to nearby faults altering their proximity to failure and thus changing earthquake probabilities we find that relative to the pre kobe seismicity kobe aftershocks were concentrated in regions of calculated coulomb stress increase and less common in regions of stress decrease we quantify this relationship by forming the spatial correlation between the seismicity rate change and the coulomb stress change the correlation is significant for stress changes greater than 0 2 1 0 bars 0 02 0 1 mpa and the nonlinear dependence of seismicity rate change on stress change is compatible with a state and rate dependent formulation for earthquake occurrence we extend this analysis to future mainshocks by resolving the stress changes on major faults within 100 km of kobe and calculating the change in probability caused by these stress changes transient effects of the stress changes are incorporated by the state dependent constitutive relation which amplifies the permanent stress changes during the aftershock period earthquake probability framed in this manner is highly time dependent much more so than is assumed in current practice because the probabilities depend on several poorly known parameters of the major faults we estimate uncertainties of the probabilities by monte carlo simulation this enables us to include uncertainties on the elapsed time since the last earthquake the repeat time and its variability and the period of aftershock decay we estimate that a calculated 3 bar 0 3 mpa stress increase on the eastern section of the arima takatsuki tectonic line attl near kyoto causes fivefold increase in the 30 year probability of a subsequent large earthquake near kyoto a 2 bar 0 2 mpa stress decrease on the western section of the attl results in a reduction in probability by a factor of 140 to 2000 the probability of a mw 6 9 earthquake within 50 km of osaka during 1997 2007 is estimated to have risen from 5 6 before the kobe earthquake to 7 11 afterward during 1997 2027 it is estimated to have risen from 14 16 before kobe to 16 22

tectonic stress state in ne japan as part of the okhotsk plate abstract an existing geodetic flow velocity model obtained by using an internal free network adjustment technique is used to derive estimates for various strain rates parameters in ne japan the greatest shortening rates of the principal strains trending e w are located in regions where much steady internal frame invariant plastic flow deformation is observed to be taking place the internal geodetic adjustment technique yielded the internal deformation in the tohoku arc most of the intraplate deformations including the much folding deformations observed in the inner zone are produced from within an interseismic transient elastic loading at a strongly coupled locked japan trench would not be needed the observed ongoing extensive ductile folding deformation in the inner zone of tohoku may mean that the geodetic strain rates causing shortening at 2 3 cm yr probably reflect the more correct level of the deformation which is steady permanent in ne japan as compared with seismic faulting data which indicate 0 5 cm yr shortening the calculated principal strain rates are used to make an interpretation for the origin of the deviatoric principal stresses within the greater regional plate tectonic framework the tectonic stress state in ne japan as part of the okhotsk plate could mostly be influenced by the okhotsk plate which is extruding southward to lessen the significant accumulated contractional deformation in ne asia in the verkhoyansk cherskii mountains the principal strain rates are n s extensional essentially everywhere in ne japan as a result of the southerly extrusion except in its southernmost leading edge in the uetsu fossa magna province where the japan alps rampart rises in front of the extrusion here an e w compressional stress state prevails a second e w contractional zone is found in north central tohoku extending from the sanriku province in the outer zone to the inner zone in the japan sea side being more prevalent in the latter zone the calculated rotation rates from the geodetic flow model are clockwise cw in both of the e w contractional regions ne japan extruding southward faces buttresses in 1 the oga ojika line ool and or a crustal weakness zone between the northern and the southern halves of tohoku approx at 38 5 n latitude and especially 2 the japanese alps rampart these obstacles cause the northern and southernmost tohoku to veer to its right and rotate cw thereby setting up the e w trending compressional deformation in their respective inner zones between the ool or the 38 5 n boundary and the kanto tectonic line ktl the sense of the differential rotations is counterclockwise ccw towards the ocean to the se the northern tohoku north of the ool and the southernmost tohoku south of the ktl cannot rotate ccw towards the ocean because of the izu block s collision in the south and the relatively strong coupling along the subduction interface beneath the japan trench in the north off sanriku the relatively stronger long term coupling between the northern tohoku and the pacific plate at the sanriku coast with respect to that in off fukushima is due to a flatter subduction of the pacific slab there increasing the plates interface contact area the flattening of the subduction dip angle was caused by ccw rotation and shifting of the northern tohoku along the dextral honjo matsushima line roughly corresponding to the ool towards the pacific and overriding of the subduction zone during the formation of the japan sea

particle deposition on the saturnian satellites from ephemeral cryovolcanism on enceladus the geologically active south pole of enceladus generates a plume of micron sized particles which likely form saturn s tenuous e ring extending from the orbit of mimas to titan interactions between these particles and satellites have been suggested though only as very thin surficial phenomena we scrutinize high resolution images with a newly developed numerical shape model of helene and find that the leading hemisphere of helene is covered by thick deposits of e ring particles which occasionally collapse to form gully like depressions the depths of the resultant gullies and near absence of small craters on the leading hemisphere indicate that the deposit is tens to hundreds of meters thick the ages of the deposits are less than several tens of my which coincides well with similar deposits found on telesto and calypso our findings as well as previous theoretical work collectively indicate that the cryovolcanic activity currently occurring on enceladus is ephemeral

saturn s icy satellites and rings investigated by cassini vims iii radial compositional variability in the last few years cassini vims the visible and infrared mapping spectrometer returned to us a comprehensive view of the saturn s icy satellites and rings after having analyzed the satellites spectral properties filacchione g capaccioni f mccord t b coradini a cerroni p bellucci g tosi f d aversa e formisano v brown r h baines k h bibring j p buratti b j clark r n combes m cruikshank d p drossart p jaumann r langevin y matson d l mennella v nelson r m nicholson p d sicardy b sotin c hansen g hibbitts k showalter m newman s 2007 icarus 186 259 290 paper i and their distribution across the satellites hemispheres filacchione g capaccioni f clark r n cuzzi j n cruikshank d p coradini a cerroni p nicholson p d mccord t b brown r h buratti b j tosi f nelson r m jaumann r stephan k 2010 icarus 206 507 523 paper ii we proceed in this paper to investigate the radial variability of icy satellites principal and minor and main rings average spectral properties this analysis is done by using 2264 disk integrated observations of the satellites and a 12 700 pixels wide rings radial mosaic acquired with a spatial resolution of about 125 km pixel using different vis and ir spectral indicators e g spectral slopes and band depths we perform a comparative analysis of these data aimed to measure the distribution of water ice and red contaminant materials across saturn s system the average surface regolith grain sizes are estimated with different indicators through comparison with laboratory and synthetic spectra these measurements highlight very striking differences in the population here analyzed which vary from the almost uncontaminated and water ice rich surfaces of enceladus and calypso to the metal organic rich and red surfaces of iapetus leading hemisphere and phoebe rings spectra appear more red than the icy satellites in the visible range but show more intense 1 5 2 0 m band depths although their orbits are close to the f ring prometheus and pandora are different in surface composition prometheus in fact appears very water ice rich but at the same time very red at vis wavelengths these properties make it very similar to a b ring particles while pandora is bluer moving outwards we see the effects of e ring particles generated by enceladus plumes which contaminate satellites surfaces from mimas out to rhea we found some differences between tethys lagrangian moons calypso being much more water ice rich and bluer than telesto among outer satellites hyperion iapetus and phoebe we observe a linear trend in both water ice decrease and in reddening hyperion being the reddest object of the population the correlations among spectral slopes band depths visual albedo and phase permit us to cluster the saturnian population in different spectral classes which are detected not only among the principal satellites and rings but among co orbital minor moons as well these bodies are effectively the connection elements both in term of composition and evolution between the principal satellites and main rings finally we have applied hapke s theory to retrieve the best spectral fits to saturn s inner regular satellites from mimas to dione using the same methodology applied previously for rhea data discussed in ciarniello et al ciarniello m capaccioni f filacchione g clark r n cruikshank d p cerroni p coradini a brown r h buratti b j tosi f stephan k 2011 icarus 214 541 555

interplate coupling distribution along the nankai trough in southwest japan estimated from the block motion model based on onshore gnss and seafloor gnss a observations