seismic reflectors beneath the central cones of aso volcano kyushu japan abstract the subsurface structure of aso volcano central kyushu japan has been imaged down to 10 km below sea level and notable features of subsurface structure in the central cones were revealed by a 3 d seismic reflection analysis the 3 d reflection analysis included reflection enhancements and 3 d migration the reflection enhancements and the nmo correction were applied on waveform data from the seismic experiment aso98 the 3 d migration with a kirchhoff integral was processed for 1397 nmo corrected traces to calculate the reflectivity at about 60 000 image points in an approximately 7 km by 7 5 km square region the results of the 3 d migration show that the subsurface structure beneath the central cones can be divided into three parts the western part the eastern part and the northwestern part bright reflectors appear in most of them and a significant discontinuity is inferred the reflector horizon at 2 km below sea level spreads beneath the western and the eastern part and is probably the top surface of the pre aso volcanic rocks or the basement rocks reflection voids appear in the western part and just beneath the active crater the reflector void in the western part implies a hot region and is most probably the known seismic anomalies such as low velocity region or attenuation region another reflector void beneath the active crater can also be associated with a hot region apparently surrounding the conduit system of the current volcanic craters the major discontinuity is located beneath the northwest flank of the central cones this discontinuity divides the northwest region with weak reflectors from other parts the discontinuity may be the trace of the oita kumamoto tectonic line which is the major tectonic line in central kyushu crossing the aso caldera

western boundary currents in the atmosphere of mars western boundary currents wbcs are an intensification of north south flow adjacent to an eastward facing meridional boundary although most familiar in the oceans where the gulf stream is the best known example wbcs also occur in the earth s troposphere the main example being the east african jet1 which is thought to play an important role in the asiatic monsoon here we identify boundary currents in a different geophysical context a numerical simulation of the atmosphere of mars in our simulation wbcs exist in association with significant cross equatorial flow and the presence of equatorial martian topography which has vertical scale far exceeding terrestrial relief2 the intensity and width of these currents depend on model parameters notably the surface drag from a comparison of our results with other martian models we suggest that wbcs have already been simulated although they were not previously identified as such3 the available observational evidence appears to be consistent with the presence of martian wbcs which may be important in the generation of global and great dust storms

temperature changes at depths to 150 metres near the active crater of aso volcano preliminary analysis of seasonal and volcanic effects abstract two holes were drilled to depths of 150 m and 70 m from the surface about 200 m from the active crater of aso volcano and quartz thermometers were installed in the holes at depth intervals of 30 m and 35 m respectively this series of observations is one of the first measurements of temperature at depth so close to an active crater the ground temperature at a depth of 2 m had an annual variation with a range of about 10 c as expected clearly corresponding to the atmospheric temperature variation but delayed by about 1 month temperatures measured at depths from 30 m to 70 m had very small annual temperature variations the range of temperature at 30 m depth was about 0 04 c the temperature at a depth of 60 m however was particularly stable probably because at this depth the hole is in the middle of a massive lava flow at depths of 70 m or more small less than 0 2 c annual temperature variations were again observed these variations are probably due to the effects of surface water descending to these levels through cracks and fissures at 120 m depth the average temperature is about 17 5 c over 5 c above the surface average temperature and the annual temperature variation has a range of about 2 c out of phase with the atmospheric changes this is probably due to the interaction of rainfall descending from the surface with convecting hotter fluids from below the temperature gradient below 100 m depth is very high with the average temperature at a depth of 150 m being about 31 c the temperature variations at this depth are dominated by long period variations with a steady decline after a peak in november december 1989 overlain by a rather irregular seasonal variation with a range of about 0 5 c october 1989 was the time of most active volcanic activity with strombolian eruptions depositing ash to a distance of 50 km from the crater accompanied by very high amplitude volcanic tremor so the temperature changes at 150 m seem to be mainly the result of volcanic activity the maximum temperature at this depth occurred 1 or 2 months after the peak of observed volcanic activity so it is likely that the temperature variations show a delayed influence of the level of volcanic activity these results show that in the unconsolidated materials often found by active volcanic craters the effects of seasonal atmospheric variations are carried to substantial depths by groundwater flows so that at aso volcano only at the maximum depth of 150 m are the temperature variations clearly dominated by the level of volcanic activity

fast numerical method for growth and retreat of subsurface ice on mars abstract subsurface water ice on mars evolves due to exchange of vapor with the atmosphere in the form of loss of ice to the atmosphere or in the form of the growth of interstitial ice described here is an accelerated numerical method for the long term evolution of subsurface ice this accelerated method is five orders of magnitude faster than explicit vapor transport calculations enabling fundamentally new types of climate models its speed matches that of purely thermal models the speedup is achieved primarily by solving time averaged equations for vapor transport and ice volume change processes incorporated are growth of interstitial pore ice retreat of pore ice retreat of an ice sheet and retreat of pore ice due to geothermal heating from below two example applications illustrate this numerical method s capabilities near the permafrost margin at 55 latitude ice is periodically depleted and slowly recharged leading to a pore ice layer estimated to be currently no more than a few meters thick at the phoenix landing site it shows the formation of a three layered structure whereby the layer of pore ice can be very thin

a new approach to assessing the burial depth of ground ice deposits and its application to proposed mer landing sites in isidis planitia 1 the recent results by the gamma ray spectrometer instrument on mars odyssey boynton et al 2002 indicate the possibility of ground ice deposits within a few meters of the surface even at low latitudes and midlatitudes the stability of ground ice deposits at these latitudes is a puzzling question to address this question we have developed the berlin mars near surface thermal model bmst a model for the thermal behavior of the martian surface with a special focus on the volatile transport within the subsurface material using the bmst we have performed a case study to derive limits on the burial depth of ground ice deposits stable over annual cycles at the mer landing sites in isidis planitia we have studied the temperature gradient within the subsurface assuming different structures and thermophysical properties for the surface and subsurface material while the results derived here will have no immediate consequences for the mer mission because isidis planitia has been demoted to a backup landing site the results show the potential and versatility of the model we have developed and give some results on the surface properties of isidis planitia

succession in a jurassic marine cavity community and the evolution of cryptic marine faunas a cavity dwelling fauna from the middle jurassic of the western interior shows a succession controlled by increasing restriction of the cavities most likely by sediment infilling the succession proceeds from large and ubiquitous bivalves to smaller serpulids cyclostome bryozoans and thecideidine brachiopods there is a concurrent decrease in biomass and percent cover this jurassic fauna demonstrates that marine cavity dwelling faunas were specifically adapted to their environments at least 160 m y ago

an attenuating structure beneath the aso caldera determined from the propagation of seismic waves the attenuation of amplitude is seen in seismic waves which pass through the central region of the aso caldera in kyushu japan it is also recognized from spectral analysis of seismic waves that the higher frequencies of the p wave are reduced in the waves which pass through the central region of the caldera it is shown that the relative attenuation increases remarkably for the frequency range of 5 to 10 hz the specific attenuation factor q of the p wave train is about 100 from the surface projection of the ray paths with low q values through the aso caldera to each station the attenuating region is located beneath the center of the caldera extending to the north of the central cones in conjunction with the low q value of the p wave and the decreases of s wave amplitudes the relative p wave residual times have comparatively large values for seismic waves passing through the central region beneath the caldera in order to attempt to provide additional information on the depth configuration of the attenuating material the ray paths of p wave s first arrivals are located in three dimensional space it indicates that the low velocity material is located beneath the center of the caldera at depths of about 6 to 9 km however lowvelocity anomalies above the depth of 6 km and below the depth of 15 km were not able to be detected because most of the available seismic ray paths had crossed the caldera at depths of about 6 to 15 km furthermore the relative residual times have numerous errors resulting from incorrect hypocenter locations origin times inhomogeneities in the structure and uncertainty of the velocity structure at shallow depths in the aso caldera refraction or reflection studies are required for an accurate estimate of the structure and more detailed properties of the attenuating material

detection of a crack like conduit beneath the active crater at aso volcano japan to constrain the source of long period tremors lpts we deployed a very dense broadband seismic network consisting of totally twenty four stations around the active crater of aso volcano in kyushu japan the spatial variation of the observed signal amplitudes reveals that the source of lpts consists of an isotropic expansion contraction and an inflation deflation of an inclined tensile crack with a strike almost parallel to the chain of craters the detected crack has a dimension of 1 km and its center is located a few hundred meters southwest of the active crater at a depth of about 1 8 km the extension of the crack plane meets the crater chain including the active fumarole at the surface suggesting that the crack has played an important role in transporting gasses and or lava to the craters from below this work also demonstrates a powerful usage of broadband seismometers as geodetic instruments to constrain subsurface structures at active volcanoes

stratigraphic relationships within martian polar cap deposits abstract deposits of layered ice and dust accumulate on the smooth and banded terrains of the north and south polar cap deposits while erosion of equator facing slopes of layered terrain expose these layers banded terrain occurs at exposures of irregular layers resulting from slight erosion of the feather edges of layers deposited on pole facing trough walls these deposits unconformably overlap onto adjacent layered terrain stripping of layers occurs in areas of strong multidirectional wind forming striped terrain local wind scour has also produced steep scarps with crescentic planform often associated with dune fields positioned immediately downwind unconformities are common within layered deposits in areas of complex topography at the north pole these indicate that episodes of deposition of 5 10 layers alternate with slight erosion of pole facing trough walls troughs that strike north south alternate between erosional widening and deepening and depositional infilling creating multiple unconformities troughs near the equatorward limit of polar deposits increase in relief by deposition on adjacent smooth terrain and locally by erosional deepening troughs may migrate poleward replacing the relief increase by depositional infilling when they near the poles

bioerosion in an equatorial middle jurassic coral sponge reef community callovian matmor formation southern israel abstract the matmor formation middle jurassic callovian 165 161 mya in southern israel contains abundant coral sponge patch reefs and large crinoids which have been extensively bioeroded by bivalves worms barnacles phoronids and others producing eight ichnospecies it is significant for the evolutionary history of bioerosion because this is the first equatorial middle jurassic boring ichnofauna to be documented when compared to contemporaneous ichnofaunas this assemblage is of average diversity and abundance but has only rare sponge borings and contains abundant specimens of oichnus paraboloides as shallow pits on crinoid stems the matmor formation surprisingly lacks carbonate hardgrounds which are otherwise abundant in subtropical and temperate equivalents

diffraction problems of 3d seismic imaging migration is essential to seismic imaging it is carried out by backward extrapolation of the wavefield registered on the observation surface the quality of images depends on the accuracy of the wavefield reconstruction at interior subsurface points from the theory based on the exact solution of the scalar wave equation it is known that for accurate wave extrapolation data must be obtained from an infinite observation surface limiting of migration apertures which is inevitable in practice leads to artefacts in extrapolated fields the distortion they cause in 2d and 3d imaging is different in 2d migration the artefacts known as truncation effects are much weaker than the signals being extrapolated and for this reason attract no special attention in 3d migration diffractions caused by an aperture edge are stronger and may create serious problems for a circular aperture their amplitudes are comparable to the amplitudes of the signals themselves the study of aperture diffractions is intended to help in the search for ways of either suppressing them efficiently or deliberately utilizing them in order to improve imaging in optics diffractions by an aperture play a constructive role in image making this research shows that the same may take place in seismic imaging

zonally symmetric response to atmospheric tidal forcing in the dusty martian atmosphere abstract we have computed a steady state zonally symmetric response of an atmospheric circulation to the combined efffects of the very large zonal mean diabatic heating and thermotidal forcing thought to exist in the dusty martian atmosphere during one of its episodic global dust storms the zonal mean components of the tidal flux convergences of momentum and heat are computed using an existing classical atmospheric tidal model constrained by the surface pressure observations at the two viking lander sites on mars the zonally symmetric response to the computed tidal flux convergences and to the zonal mean heating of the airborne dust is then computed by a nearly inviscid two dimensional 2 d model previously used to study the mars hadley circulation tidally induced easterly forces at southern summer solstice can extend the core of the descending branch of the zonally symmetric circulation from 50 to 55 n which is consistent with viking lander 2 surface pressure observations but not far enough polewa

bathymetric distribution of ichnocoenoses from recent subtropical algal nodules off fraser island eastern australia abstract coralline algal nodules living on the subtropical shelf off fraser island eastern australia from the inner to the uppermost outer shelf from 28 to 117 m water depth are pervasively bioeroded five ichnogenera have been identifed as nodule borers comprising one ichnotaxon attributed to bivalves gastrochaenolites one to sponges entobia and three to polychaetes and barnacles trypanites maeandropolydora rogerella microtraces comparable to those produced by fungi algae bacteria and or sponges are also present two ichnocoenoses have been recognised the shallow water ichnocoenosis egtm occurs at 60 m and shallower depths and includes all identified ichnogenera the deep water ichnocoenosis from 68 to 117 m is characterised by trypanites and the trypanites maeandropolydora network tm ichnocoenosis with a generally higher boring density than in shallower nodules decreasing size of algal nodules and reduced thickness of the coralline thalli probably explain the decrease in diversity of ichnogenera with depth as the larger bioeroders are excluded from the ichnoassemblages lower growth rates favour higher density of bioerosion in deeper algal nodules

diverse sclerozoan assemblages encrusting large bivalve shells from the callovian middle jurassic of southern poland a diverse sclerozoan assemblages consisting of both encrusting and boring biota are described from the large limid bivalves ctenostreon from the callovian hardground setting of zalas in southern poland at least 27 encrusting and seven bioerosion taxa are reported here which makes this assemblage not only one of the most diverse in the middle jurassic but the richest in encrusting taxa from the callovian the encrusters consist of cryptic biota of which sedentary polychaetes and cyclostome bryozoans dominate with respect to both species number and abundance the bioerosion traces are dominated by tiny pits referred to the ichnogenus oichnus probably made by some soft bodied biota in the present case followed by the borings of acrothoracican barnacles rogerella the first colonizers of the bivalve shells probably were borers as they only occur in the host shells the encrusting pioneers presumably were oysters and oyster like bivalves followed by opportunistic serpulid sabellid polychaetes and cyclostome bryozoans the last colonizers were calcisponges and thecideide brachiopods in comparison to the only known late callovian shallow and reef associated tropical sclerozoans of israel the assemblage from the open marine deeper setting of poland is much richer in encrusting taxa such a surprising high encruster diversity in the marine northern paleo latitude may have resulted from the deeper and calmer environment with a both reduced sedimentation rate and algal cover and without any significant salinity changes the factors that are thought to have impacted the tropical and shallow marine sclerozoans from israel

improved general circulation models of the martian atmosphere from the surface to above 80 km we describe a set of two new generation general circulation models of the martian atmosphere derived from the models we originally developed in the early 1990s the two new models share the same physical parameterizations but use two complementary numerical methods to solve the atmospheric dynamic equations the vertical resolution near the surface has been refined and the vertical domain has been extended to above 80 km these changes are accompanied by the inclusion of state of the art parameterizations to better simulate the dynamical and physical processes near the surface boundary layer scheme subgrid scale topography parameterization etc and at high altitude gravity wave drag in addition radiative transfer calculations and the representation of polar processes have been significantly improved we present some examples of zonal mean fields from simulations using the model at several seasons one relatively novel aspect previously introduced by wilson 1997 is that around northern winter solstice the strong pole to pole diabatic forcing creates a quasi global angular momentum conserving hadley cell which has no terrestrial equivalent within such a cell the coriolis forces accelerate the winter meridional flow toward the pole and induce a strong warming of the middle polar atmosphere down to 25 km this winter polar warming had been observed but not properly modeled until recently in fact thermal inversions are generally predicted above one and often both poles around 60 70 km however the mars middle atmosphere above 40 km is found to be very model sensitive and thus difficult to simulate accurately in the absence of observations

thermal inertia mapping of mars from 60 s to 60 n twenty micrometer brightness temperatures are used to derive the thermal inertia for 81 of the martian surface between latitudes 60 these data were acquired by the two viking infrared thermal mappers in 1977 and 1978 following the two global dust storms of 1977 the spatial resolution used is 2 in latitude by 2 in longitude and the total range in derived inertia is 1 to 15 10 3 cal cm 2 sec 12 k 1 the distribution of thermal inertia is strongly bimodal with all values of thermal inertia less than 4 10 3 cal cm 2 sec 12 k 1 being associated with three disjoint bright regions mostly in the northern hemisphere sufficient dust is raised in global storms to provide fine material adequate to produce these low inertia areas but the specific deposition mechanism has not been defined at the low resolution used no complete exposures of clean rock were found there is some tendency for darker material to be associated with higher thermal inertia although the trend is far from one to one the distribution of high and low inertia areas is sufficiently nonrandom to produce a variation in whole disk brightness temperature with central meridian longitude this variation and the change in surface kinetic temperature associated with dust storms are factors in establishing the whole disk brightness temperature at radio and infrared wavelengths and will be important for those who use mars as a calibration source

h l chondrite lapaz icefield 031047 a feather of icarus abstract antarctic meteorite lap 031047 is an ordinary chondrite composed of loosely consolidated chondritic fragments its petrography oxygen isotopic composition and geochemical inventory are ambiguous and indicate an intermediate character between h and l chondrites petrographic indicators suggest lap 031047 suffered a shock metamorphic overprint below 10 gpa which did not destroy its unusually high porosity of 27 vol metallographic textures in lap 031047 indicate heating above 700 c and subsequent cooling which caused massive transformation of taenite to kamacite the depletion of thermally labile trace elements the crystallization of chondritic glass to microcrystalline plagioclase of unusual composition and the occurrence of coarsely crystallized chondrule fragments is further evidence for post metamorphic heating to 700 750 c however this heating event had a transient character because olivine and low ca pyroxene did not equilibrate nearly complete degassing up to very high temperatures is indicated by the thorough resetting of lap 031047 s ar ar reservoir 100 55 ma ago a noble gas cosmic ray exposure age indicates it was reduced to a meter size fragment at

a new equatorial very shallow marine sclerozoan fauna from the middle jurassic late callovian of southern israel abstract tropical jurassic sclerozoan faunas are poorly known yet they are critical to our understanding of jurassic biogeography and the evolution of hard substrate communities a diverse assemblage of hard substrate fossils is here described from subunits 53 and 54 of the upper matmor formation callovian of hamakhtesh hagadol in the negev desert of southern israel this region was on or very near the equator during the middle jurassic the fauna is dominated by flat platter shaped sponges actostroma and scleractinian corals microsolena some of which have the depressed centers and raised rims of microatolls which form today in the shallowest subtidal zone associated with reef systems the coral and calcareous sponge platters are encrusted on their top surfaces by one species of serpulid worm and many small coral and sponge recruits with narrow attachments and mushroom shaped or conical skeletons growing upwards the undersurfaces of the platters are encrusted by another serpulid species at least two calcareous sponges rare cyclostome bryozoans oysters plicatulid bivalves and numerous thecideide brachiopods the first known from the jurassic of the region the upper and undersurfaces of the platters are often bored by bivalves forming the ichnospecies gastrochaenolites torpedo these borings were occasionally reoccupied by a nestling mytilid bivalve on the undersurfaces of the skeletal platters this encrusting fauna of the matmor formation apparently lived in a shallow lagoon on the landward side of a coral reef the fossils in the surrounding muddy sediments are primarily echinoids oysters and rhynchonellid and terebratulid brachiopods this sclerozoan fauna is an evidence that jurassic tropical hard substrate faunas were serpulid rich and bryozoan poor as predicted but more diverse at twelve species than expected this community was also ecologically divided into open and cryptic assemblages like its jurassic equivalents in the temperate and subtropical waters of europe and north america

the 2016 kumamoto mw 7 0 earthquake a significant event in a fault volcano system the 2016 kumamoto earthquake sequence occurred on the futagawa hinagu fault zone near the aso volcano on kyushu island the sequence was initiated with two major m w 6 0 foreshocks and the mainshock m w 7 0 occurred 25 h after the second major foreshock we combine gps strong motion synthetic aperture radar images and surface offset data in a joint inversion to resolve the kinematic rupture process of the mainshock and coseismic displacement of the foreshocks the joint inversion results reveal a unilateral rupture process for the mainshock involving sequential rupture of four major asperities the slip area of the foreshocks and mainshock and the aftershock loci form a detailed complementary pattern the mainshock rupture terminates near the rim of the caldera leaving a 10 km long gap of aftershocks this area is characterized by high temperature and low shear wave velocity density and resistivity which may be related to the partially melted geothermal condition ductile material property near the volcano may act as a material barrier to the dynamic rupture topographic weight of the caldera increases compressional normal stress on the fault plane which may behave as a stress barrier long term seismic hazard and deformation behaviors related to these two types of barriers are discussed in terms of the associated frictional mechanism significant postseismic creeps observed near the volcano area indicates a velocity strengthening frictional behavior near the rupture termination which confirms that the material barrier mechanism is likely the dominant rupture termination mechanism

high resolution thermal inertia mapping from the mars global surveyor thermal emission spectrometer abstract high resolution thermal inertia mapping results are presented derived from mars global surveyor mgs thermal emission spectrometer tes observations of the surface temperature of mars obtained during the early portion of the mgs mapping mission thermal inertia is the key property controlling the diurnal surface temperature variations and is dependent on the physical character of the top few centimeters of the surface it represents a complex combination of particle size rock abundance exposures of bedrock and degree of induration in this work we describe the derivation of thermal inertia from tes data present global scale analysis and place these results into context with earlier work a global map of nighttime thermal bolometer based thermal inertia is presented at 1 4 per pixel resolution with approximately 63 coverage between 50 s and 70 n latitude global analysis shows a similar pattern of high and low thermal inertia as seen in previous viking low resolution mapping significantly more detail is present in the high resolution tes thermal inertia this detail represents horizontal small scale variability in the nature of the surface correlation with albedo indicates the presence of a previously undiscovered surface unit of moderate to high thermal inertia and intermediate albedo this new unit has a modal peak thermal inertia of 180 250 j m 2 k 1 s 1 2 and a narrow range of albedo near 0 24 the unit covering a significant fraction of the surface typically surrounds the low thermal inertia regions and may comprise a deposit of indurated fine material local 3 km resolution maps are also presented as examples of eolian fluvial and volcanic geology some impact crater rims and intracrater dunes show higher thermal inertias than the surrounding terrain thermal inertia of aeolian deposits such as intracrater dunes may be related to average particle size outflow channels and valleys consistently show higher thermal inertias than the surrounding terrain generally correlations between spatial variations in thermal inertia and geologic features suggest a relationship between the hundred meter scale morphology and the centimeter scale surface layer

plate tectonic evolution of the southern margin of eurasia in the mesozoic and cenozoic abstract thirteen time interval maps were constructed which depict the triassic to neogene plate tectonic configuration paleogeography and general lithofacies of the southern margin of eurasia the aim of this paper is to provide an outline of the geodynamic evolution and position of the major tectonic elements of the area within a global framework the hercynian orogeny was completed by the collision of gondwana and laurussia whereas the tethys ocean formed the embayment between the eurasian and gondwanian branches of pangea during late triassic early jurassic times several microplates were sutured to the eurasian margin closing the paleotethys ocean a jurassic cretaceous north dipping subduction boundary was developed along this new continental margin south of the pontides transcaucasus and iranian plates the subduction zone trench pulling effect caused rifting creating the back arc basin of the greater caucasus proto south caspian sea which achieved its maximum width during the late cretaceous in the western tethys separation of eurasia from gondwana resulted in the formation of the ligurian penninic pieniny magura ocean alpine tethys as an extension of middle atlantic system and a part of the pangean breakup tectonic system during late jurassic early cretaceous times the outer carpathian rift developed the opening of the western black sea occurred by rifting and drifting of the western central pontides away from the moesian and scythian platforms of eurasia during the early cretaceous cenomanian the latest cretaceous paleogene was the time of the closure of the ligurian pieniny ocean adria alcapa terranes continued their northward movement during eocene early miocene times their oblique collision with the north european plate led to the development of the accretionary wedge of the outer carpathians and its foreland basin the formation of the west carpathian thrusts was completed by the miocene the thrust front was still propagating eastwards in the eastern carpathians during the late cretaceous the lesser caucasus sanandaj sirjan and makran plates were sutured to the iranian afghanistan plates in the caucasus caspian sea area a north dipping subduction zone jumped during paleogene to the scythian turan platform the shatski terrane moved northward closing the greater caucasus basin and opening the eastern black sea the south caspian underwent reorganization during oligocene neogene times the southwestern part of the south caspian basin was reopened while the northwestern part was gradually reduced in size the collision of india and the lut plate with eurasia caused the deformation of central asia and created a system of nw se wrench faults the remnants of jurassic cretaceous back arc systems oceanic and attenuated crust as well as tertiary oceanic and attenuated crust were locked between adjacent continental plates and orogenic systems

evidence for enhanced hydration on the northern flank of olympus mons mars in this paper we report about a small region on the northern scarp of olympus mons showing an increase of the 3 m hydration band in the omega spectra together with low superficial temperatures although water ice clouds can occurs on the flank of big martian volcanoes radiative transfer modeling indicates that atmospheric water ice alone cannot justify the shape of the observed band a fit of the 1 9 3 m absorption features is obtained by hypothesizing that the study region consists of a mixture of dust and water ice covered by an optically thin 0 08 at 3 m layer of dust thermal modeling also suggests that water ice in this region may be stable during most of the martian year due to the saturation of the atmosphere if water ice is responsible for the observed spectral behavior it might consist of a number of ice or snow patches possibly deposited in small depressions

orographic control of storm zones on mars low pressure cyclones and their accompanying frontal systems in the middle latitudes of the earth s troposphere develop travel eastwards and decay preferentially within latitudinally and longitudinally confined geographical regions known as storm zones1 these zones can be readily identified in the circulation statistics of terrestrial weather systems2 mars like the earth is a rapidly rotating solid planet and has a seasonally varying shallow atmosphere large scale orography and in a broadly defined context continental structures3 although there are also important differences between the two planets travelling weather systems do exist on mars3 this raises the question of whether storm zones also occur there and if so by what mechanisms here we report the results of numerical simulations of global atmospheric circulation patterns on mars we find that storm zones can exist during the northern winter and that continental scale orography rather than surface thermal contrasts is the main factor determining the development of these zones storm zones on mars should play an important role in the martian climate cycle4 5 by influencing the transport of for example heat momentum water vapour and atmospheric dust3 6 8 towards the poles

the spatial distribution of rocks on mars abstract the spatial distribution of rocks exposed at the surface of mars has been mapped using viking infrared thermal mapper irtm observations overall there are no regions on the surface of mars at a scale of 1 1 in latitude and longitude that are rock free the modal value of rock abundance is 6 areal coverage with no areas having more than 30 35 rock cover the model developed to determine rock abundance relates the thermal emission in each of the four surface sensing irtm bands to temperature contrasts within the field of view non unit thermal emissivity due to absorption bands in the surface materials and the absorption and scattering of the outgoing energy by atmospheric dust and water ice each of these effects produce characteristic spectral and diurnal signatures allowing them to be separated the temperature contrasts provide a means to determine both the abundance of exposed rocks and the fine component thermal intertia rock abundance alone does not produce the observed variation in bulk thermal inertia of the surface low inertia fine bright surfaces have fewer rocks exposed than do high inertia coarse dark surfaces rock abundance does not correlate well with the rms slope nor reflectivity determined from delay doppler radar measurements there is however a possible correlation between rms slope determined from continuous wave radar observations dual polarization radar measurements which provide the best radar measure of small scale roughness indicate that the tharsis volcanic region is very rough whereas thermal measurements indicate very few rocks and a covering of dust together these observations suggest an approximately 1 m thick mantle of fines covering a very rough subsurface this fine material may be an aeolian deposit of dust storm fallout valles marineris together with several major channels and chaotic terrains have high rock abundances as does the acidalia planitia basin this observed distribution may reflect the initial deposition of coarse material associated with channel formation syrtis major is unique in having a high inertia but a very low rock abundance together with low radar roughness these observations are consistent with mantling of rocks by sand the observed distribution of rocks and fines indicates that aeolian processes both erosional and depositional play a dominant role in shaping the present martian surface

limits on the burial depth of glacial ice deposits on the flanks of hecates tholus mars 1 an analysis of data obtained by the hrsc camera on mars express revealed morphological evidence for the existence of glacial deposits on the flank of hecates tholus e hauber et al 2004 crater counts indicate a very young age in the range of several million years only in this study we have assessed limits for the burial depth of a still existing ice deposit protected by an overlying dust layer our first results indicate a high likelihood to find ice within only a few meters below the surface in this region

palaeoecology and evolution of marine hard substrate communities abstract marine organisms have occupied hard substrates since the archaean shells rocks wood and sedimentary hardgrounds offer relatively stable habitats compared to unconsolidated sediments but the plants and animals which inhabit them must develop means to gain and defend this premium attachment space hard substrate communities are formed by organisms with a variety of strategies for adhering to and or excavating the substrates they inhabit while mobile grazers organically attached and even soft bodied organisms may leave evidence of their former presence in ancient hard substrate communities a superior fossil record is left by sessile encrusters with mineralised skeletons and by borers which leave trace fossils furthermore encrusters and borers are preserved in situ retaining their spatial relationships to one another and to the substrate spatial competition ecological succession oriented growth and differential utilisation of exposed vs hidden substrate surfaces can all be observed or inferred hard substrate communities are thus excellent systems with which to study community evolution over hundreds of millions of years here we review the research on modern and ancient hard substrate communities and point to some changes that have affected them over geological time scales such changes include a general increase in bioerosion of hard substrates particularly carbonate surfaces through the phanerozoic this is at least in part analogous to the infaunalisation trends seen in soft substrate communities encrusting forms show an increase in skeletalisation from the palaeozoic into the mesozoic and cenozoic which may be a response to increasing levels of predation hard substrate communities considering borers and encrusters together show a rough increase in tiering through the phanerozoic which again parallels trends seen in soft substrate communities this extensive review of the literature on living and fossil hard substrate organisms shows that many opportunities remain for large scale studies of trends through time at the community and clade levels palaeontologists will especially benefit by closer integration of their work with that of neontologists particularly in aspects of ecology such as larval recruitment competition and succession

three dimensional seismic velocity structure beneath aso volcano kyushu japan tomographic results for p and s wave velocity structure beneath the active aso volcano kyushu japan using 800 well recorded earthquakes and ten shots recorded by an eight station seismic network are presented a 68 variance reduction was achieved upon simultaneous inversion for hypocenter and velocity structure well resolved velocity anomalies associated with the active crater reveal heterogeneity up to 26 slower and 18 faster in p velocity and up to 31 slower and 22 faster in s velocity than the one dimensional model the largest anomaly is seen over the upper 11 km in the central and northern parts beneath the central cones two low velocity regions are imaged the first region a 10 15 km region encompassing the upper 3 km centered near the caldera wall at tateno valley is characterized by p velocities up to 19 slower 20 for s the second low velocity region is associated with the central cones and active magma conduit system at 6 km depth velocities as low as 4 3 km s up to 26 in p and 2 km s 31 slower in s characterize the 7 km wide volume the magma chamber is roughly spherical in shape centered at 6 km depth flattens at 10 km depth and is located between mt kishima mt eboshi and mt naka the present focus of magmatism a sharp velocity contrast at the depth of 3 km with high velocities to the southwest and lower velocities to the northeast characterizes different abutting structures associated with the oita kumamoto tectonic line

thermal and albedo mapping of the polar regions of mars using viking thermal mapper observations 1 north polar region we present the first maps of the apparent thermal inertia and albedo of the south polar region of mars the observations used to create these maps were acquired by the infrared thermal mapper irtm instruments on the two viking orbiters over a 30 day period in 1977 during the martian late southern summer season the maps cover the region from 60 s to the south pole at a spatial resolution of 1 of latitude thus completing the initial thermal mapping of the entire planet the analysis and interpretation of these maps is aided by the results of a one dimensional radiative convective model which is used to calculate diurnal variations in surface and atmospheric temperatures and brightness temperatures at the top of the atmosphere for a range of assumptions concerning dust optical properties and dust optical depths the maps show that apparent thermal inertias of bare ground regions decrease systematically from 60 s to the south pole in unfrosted regions close to the south pole apparent thermal inertias are among the lowest observed anywhere on the planet on the south residual cap apparent thermal inertias are very high due to the presence of co2 frost in most other regions of mars best fit apparent albedos based on thermal emission measurements are generally in good agreement with actual surface albedos based on broadband solar reflectance measurements however in the frost free region poleward of 75 s best fit apparent albedos are significantly higher than measured lambert albedos implying that measured brightness temperatures in this area are up to 15 k colder than would be expected for surfaces with the same measured albedos during this season the one dimensional atmospheric model calculations also predict anomalously cold brightness temperatures close to the pole during late summer and after considering a number of alternatives it is concluded that the net surface cooling due to atmospheric dust is the best explanation for this phenomenon the observed systematic decrease in apparent thermal inertia from 60 s to the south pole during this season is also consistent with the predictions of atmospheric model calculations the region of lowest apparent thermal inertia close to the pole which includes the south polar layered deposits is interpreted to be mantled by a continuous layer of aeolian material that must be at least a few millimeters thick the low thermal inertias mapped in the south polar region imply an absence of surface water ice deposits which is consistent with viking mars atmospheric water detector mawd measurements which show low atmospheric water vapor abundances throughout the summer season however these observations do not necessarily imply a complete absence of water thermal model calculations that can reproduce observed diurnal temperature variations in the south polar region show that annual maximum subsurface temperatures at depths ranging from 4 to 20 cm are cold enough to permit the stability of ground ice deposits even if they are in excellent diffusive contact with the atmosphere therefore the presence of near surface ground ice in the south polar region is not inconsistent with the viking irtm and mawd observations

steady subsidence of a repeatedly erupting caldera through insar observations aso japan the relation between unrest and eruption at calderas is still poorly understood aso caldera japan shows minor episodic phreatomagmatic eruptions associated with steady subsidence we analyse the deformation of aso using sar images from 1993 to 2011 and compare it with the eruptive activity although the dataset suffers from limitations e g atmospheric effects coherence loss low signal to noise ratio we observe a steady subsidence signal from 1996 to 1998 which suggests an overall contraction of a magmatic source below the caldera centre from 4 to 5 km depth we propose that the observed contraction may have been induced by the release of the magmatic fluids feeding the eruptions if confirmed by further data this hypothesis suggests that degassing processes play a crucial role in triggering minor eruptions within open conduit calderas such as at aso our study underlines the importance of defining any eruptive potential also from deflating magmatic systems with open conduit

influence of a variable thermal conductivity on the thermochemical evolution of mars 1 the influences of variations in thermal conductivity due to composition temperature and pressure in mantle and crust on the thermochemical evolution of mars have been examined with parameterized convection models we use a temperature and pressure dependent thermal conductivity in the mantle and column averaged values between 1 5 and 4 wm 1k 1 for the crust with 2 wm 1k 1 as the representative value for a basaltic crust the major characteristic of the models is a slower cooling of the upper mantle with a long existing global partial melt zone and a stronger crustal production late in the evolution compared to earlier models which assume a constant thermal conductivity of 4 wm 1k 1 to explain the observed crustal thickness and the early crustal formation on mars the formation of an enriched primordial crust is required recent volcanism can be explained by lateral temperature variations that are caused by thickness variations of the low conducting crust these melt zones which occur underneath thicker than average crust may be the source region for the observed longstanding volcanism in tharsis and elysium instead of plumes rising from the core mantle boundary the evolution of the elastic lithosphere is characterized by a transition at which the elastic strength is first provided by the crust and later also by the upper mantle this finding may explain the estimated elastic lithosphere thickness of less than 16 km in the noachian and more than 100 km in the hesperian and amazonian

dynamical modeling of a planetary wave mechanism for a martian polar warming abstract a dynamical mechanism for the martian atmospheric polar warming observed by the viking irtm during the 1977 winter solstice dust storm and a similar one possibly observed by mariner 9 in 1971 is proposed and investigated using a simplified nonlinear model the model is of a type previously used to successfully simulate the essential aspects of terrestrial sudden stratospheric warmings the dynamical mechanism is in part very similar fundamentally to that responsible for these warmings involving planetary scale waves a number of numerical experiments have been conducted to assess the basic viability of such a mechanism for the martian polar warming and to examine its sensitivity to several factors these experiments demonstrate that a planetary wave mechanism can produce a polar warming with the magnitude and suddenness of that observed a planetary wave mechanism must primarily involve wavenumber 1 as wavenumber 2 is too strongly vertically trapped to produce a warming like that observed the necessary wave forcing in the present model can be topographic mechanical or thermal and nonstationary and is relatively large but certainly plausible the strong radiative damping in the mars atmosphere acts to substantially inhibit a warming through its effects on both the zonal flow and the wave dissipation plays a greater role relative to transience in a model martian warming of the type studied here than in a sudden stratospheric warming increasing radiative damping during a warming due to higher temperatures and greater dust loading may play a role in yielding a relatively rapid cooling phase for the mars warming event the residual mean meridional circulation during a model warming entails strong poleward and downward flow into high northern latitudes throughout a very deep region this probably indicates similar transport of atmospheric dust as well as water such transports are of considerable potential significance for both the dust and water cycles on mars

near surface temperatures at proposed mars exploration rover landing sites 1 minimum nighttime temperatures at the mars exploration rover mer landing sites may limit power available for science activities and thus mission lifetime here 1 m air temperatures at the end of the nominal 90 sol primary mission are derived for the four primary and three previously considered mer landing sites based on mars global surveyor thermal emission spectrometer thermal inertia and albedo estimated opacity and predictions of air temperatures from a one dimensional atmospheric model taking these results and mapping them onto the probability density distribution of the landing ellipses shows that of the air temperatures of the primary sites sinus meridiani hematite is the coldest with an 8 chance of encountering minimum nighttime temperatures below the 176 k value considered a practical limit for operations elysium and gusev are at 7 and 3 respectively whereas isidis has no computed temperatures below 191 k for the hematite site preliminary observations and interpretations are also made using high resolution odyssey thermal imaging system predawn images

topography and stratigraphy of martian polar layered deposits abstract topography and stratigraphy of young sediments in the martian north polar region are being studied from high resolution viking orbiter images to test and constrain theories of terrain evolution driven by cyclical climate change several steepened slopes upon which layers are exposed in section were found to have local relief of 200 to 800 m and slopes ranging from 1 to 8 first attempts to calculate average layer thicknesses from portions of sections yielded results ranging from 14 to 46 m linearly correlated with slope in some cases under the assumption of short range lateral continuity a greater number of layers was inferred to be present than was actually resolved on a particular section when apparent layer thickness are revised accordingly the correlation with slope is destroyed we conclude that images of the shallowest sloping sections of layered deposits should yield the most stratigraphic information and layers thinner than 14 m may occur indeed they may even be common or typical because of the sensitivity of summer frost distribution to local slope and other properties of exposed strata interseasonal comparisons of images promise to enhance the capability to detect layers and differentiate them by material properties

vnir multispectral observations of aqueous alteration materials by the pancams on the spirit and opportunity mars exploration rovers multispectral visible and near infrared vnir observations from the mars exploration rover pancam multispectral stereo camera systems are consistent with materials having been subjected to various aqueous processes ferric oxides in the form of hematite in the burns and grasberg formations of meridiani planum have been well characterized by opportunity on the basis of strong 535 and 864 nm absorptions and positive 754 1009 nm and 934 1009 nm slopes on the rim of noachian aged endeavour crater opportunity has observed light toned veins with high ca and s as determined by the rover s alpha particle x ray spectrometer apxs and a negative 934 1009 nm slope in vnir spectra extracted from pancam data indicative of a 1000 nm h2o overtone absorption together these observations indicate that the veins are composed of gypsum rocks overturned by opportunity on the murray ridge portion of the endeavour crater rim display dark and light toned coatings the dark toned coatings have a red featureless slope that is consistent with the slope observed in laboratory spectra of high valence manganese oxide minerals potential mn oxide coatings may also be associated with some exposures of the grasberg formation apxs results for high mg and s in the light toned coatings of the murray ridge overturned rocks and a negative 934 1009 nm slope are consistent with hydrated mg sulfates opportunity has also observed spectral features in rocks that are consistent with orbital observations of fe smectites as well as al smectites and possible hydrated silica in light toned fracture fill materials the spirit rover observed sulfate rich light toned soils exposed by the rover s wheels several of these soil observations contained spectral features such as a broad absorption centered near 800 nm consistent with ferric sulfate minerals a finding confirmed by the rover s mossbauer spectrometer spirit also excavated light toned si rich soils these soils have a flat near infrared spectrum with a drop in reflectance from 934 1009 nm that is consistent with free water contained in voids or adsorbed onto the surface of the silica

low velocity zones in the crust beneath aso caldera kyushu japan derived from receiver function analyses aso volcano in central kyushu island in southwest japan has a large caldera 18 25 km that formed by the ejection of more than 600 km3 of deposits 89 thousand years ago we calculated receiver functions from teleseismic waveform data obtained from densely distributed stations in and around the caldera we estimated the crustal s wave velocity structure from the receiver functions by using genetic algorithm inversion we detected a low velocity zone vs 2 2 km s at a depth of 8 15 km beneath the eastern flank of the central cones a sill like deformation source has been detected at a depth of 15 5 km by analyses of gps data and a swarm of low frequency earthquakes exists at depths of 15 25 km just beneath this low velocity zone magma may be newly generated and accumulated in this low velocity zone as a result of hot intrusions coming from beneath it except for the region beneath the eastern flank of the central cones a second low velocity zone vs 1 9 km s extends in and around the caldera at a depth of 15 23 km although phenomena representing intrusions have not been detected below it from the estimated velocity structure these low velocity zones are interpreted to contain a maximum of 15 melt or 30 water

characteristics of isolated hybrid tremor hbt during a calm activity period at aso volcano isolated type tremors having two events with different dominant frequencies are characteristic seismological phenomena observed during the fumarolic activity stage at aso volcano these isolated tremors are called hybrid tremors hbt and comprise two parts an initial part named the hf part with a dominant frequency in the high frequency region approximately 10 hz and the following part named the lf part with a dominant frequency in the low frequency region approximately 2 hz the lf part is observed after the hf part and the hbt is accompanied by a long period tremor lpt hypocenters and source parameters are estimated using seismograms recorded at 64 stations around nakadake crater the amplitude distributions of all hf parts have almost similar trends similarly the amplitude distributions of all lf parts have almost similar trends however the amplitude distributions of hf and lf parts are not similar from these results we proposed that the hypocenters and source parameters of hf and lf parts are not common but each of them have common hypocenters and source parameters the hypocenter region of hf parts was estimated to be just beneath the fumarole region south of the 1st crater the volume fluctuation is the major source factor the hypocenter region of lf parts is estimated to be at a depth of approximately 300 m beneath the first crater the strike slip component is the major source parameter the hypocentral depth of lf parts is located at the upper end of the crack estimated to be the source of the lpts the lpts and hbts are observed almost simultaneously we consider that volcanic fluid is involved in the source mechanisms of both hbt and lpt

a preparation zone for volcanic explosions beneath naka dake crater aso volcano as inferred from magnetotelluric surveys abstract the 1st crater of naka dake aso volcano is one of the most active craters in japan and known to have a characteristic cycle of activity that consists of the formation of a crater lake drying up of the lake water and finally a strombolian type eruption recent observations indicate an increase in eruptive activity including a decrease in the level of the lake water mud eruptions and red hot glows on the crater wall temporal variations in the geomagnetic field observed around the craters of naka dake also indicate that thermal demagnetization of the subsurface rocks has been occurring in shallow subsurface areas around the 1st crater volcanic explosions act to release the energy transferred from magma or volcanic fluids measurement of the subsurface electrical resistivity is a promising method in investigating the shallow structure of the volcanic edifices where energy from various sources accumulates and in investigating the behaviors of magma and volcanic fluids we carried out audio frequency magnetotelluric surveys around the craters of naka dake in 2004 and 2005 to determine the detailed electrical structure down to a depth of around 1 km the main objective of this study is to identify the specific subsurface structure that acts to store energy as a preparation zone for volcanic eruption two dimensional inversions were applied to four profiles across the craters revealing a strongly conductive zone at several hundred meters depth beneath the 1st crater and surrounding area in contrast we found no such remarkable conductor at shallow depths beneath the 4th crater which has been inactive for 70 years finding instead a relatively resistive body the distribution of the rotational invariant of the magnetotelluric impedance tensor is consistent with the inversion results this unusual shallow structure probably reflects the existence of a supply path of high temperature volcanic gases to the crater bottom we propose that the upper part of the conductor identified beneath the 1st crater is mainly composed of hydrothermally altered zone that acts both as a cap to upwelling fluids supplied from deep level magma and as a floor to infiltrating fluid from the crater lake the relatively resistive body found beneath the 4th crater represents consolidated magma these results suggest that the shallow conductor beneath the active crater is closely related to a component of the mechanism that controls volcanic activity within naka dake

global distribution of neutrons from mars results from mars odyssey global distributions of thermal epithermal and fast neutron fluxes have been mapped during late southern summer northern winter using the mars odyssey neutron spectrometer these fluxes are selectively sensitive to the vertical and lateral spatial distributions of h and co 2 in the uppermost meter of the martian surface poleward of 60 latitude is terrain rich in hydrogen probably h 2 o ice buried beneath tens of centimeter thick hydrogen poor soil the central portion of the north polar cap is covered by a thick co 2 layer as is the residual south polar cap portions of the low to middle latitudes indicate subsurface deposits of chemically and or physically bound h 2 o and or oh