remote sensing estimates of glacier mass balances in the himachal pradesh western himalaya india abstract although they correspond to an important fraction of the total area of mountain glaciers 33 000 km2 out of 546 000 km2 himalayan glaciers and their mass balance are poorly sampled for example between 1977 and 1999 the average area surveyed each year on the field was 6 8 km2 only no direct mass balance measurement is available after 1999 to contribute to fill this gap we use remote sensing data to monitor glacier elevation changes and mass balances in the spiti lahaul region 32 2 n 77 6 e himachal pradesh western himalaya india our measurements are obtained by comparing a 2004 digital elevation model dem to the 2000 srtm shuttle radar topographic mission topography the 2004 dem is derived from two spot5 satellite optical images without any ground control points this is achieved thanks to the good on board geolocation of spot5 scenes and using srtm elevations as a reference on the ice free zones before comparison on glaciers the two dems are analyzed on the stable areas surrounding the glaciers where no elevation change is expected two different biases are detected a long wavelength bias affects the spot5 dem and is correlated to an anomaly in the roll of the spot5 satellite a bias is also observed as a function of altitude and is attributed to the srtm dataset both biases are modeled and removed to permit unbiased comparison of the two dem on the 915 km2 ice covered area digitized from an aster image on most glaciers a clear thinning is measured at low elevations even on debris covered tongues between 1999 and 2004 we obtain an overall specific mass balance of 0 7 to 0 85 m a water equivalent depending on the density we use for the lost or gained material in the accumulation zone this rate of ice loss is twice higher than the long term 1977 to 1999 mass balance record for himalaya indicating an increase in the pace of glacier wastage to assess whether these ice losses are size dependant all glaciers were classified into three samples according to their areal extent all three samples show ice loss the loss being higher for glaciers larger than 30 km2 in the case of the benchmark chhota shigri glacier a good agreement is found between our satellite observations and the mass balances measured on the field during hydrological years 2002 2003 and 2003 2004 future studies using a similar methodology could determine whether similar ice losses have occurred in other parts of the himalaya and may allow evaluation of the contribution of this mountain range to ongoing sea level rise

the structural state of the former lower continental crust in calabria s italy in the northern serre s italy a continuous section through a former lower continental crust is exposed schenk 1984 1985 these granulite facies rocks have not been penetratively deformed during their uplift to higher crustal levels therefore they allow to study the structural state of the lower continental crust most rockforming minerals among them ortho and clinopyroxene and cordierite show recrystallization structures quarz basal subgrain boundaries are developed in lower levels of the lower crust and disappear toward higher levels in addition to dimensional orientations of the rockforming minerals the preferred crystallographic orientations of plagioclases cordierite amphibole pyroxenes and rarely quartz reflect the strain orientation of the prograde high t deformation during this deformation the stretching direction was constant nne ssw throughout the exposed lower crustal section shear indicators are rare this points to the fact that deformation has been homogeneous and coaxial flattening there is only a small variation in orientation and strength of textures throughout the exposed lower crust therefore neighbouring layers of different composition rather than different deformation might serve as seismic reflectors in the former lower crust

the p t d development at the basement cover boundary in the north eastern tauern window eastern alps alpine continental collision at the basement cover boundary of the north eastern tauern window eastern alps the following alpine p t d development has been reconstructed on the basis of macro and micro structures as well as preferred crystallographic orientations mineral parageneses and compositions during increasing p t conditions in the greenschist facies a first period of deformation produced imbrication of the basement gneisses and cover sediments and then monoclinal folds up to the kilometre scale tectonic transport was continuously top to the ene a second period of deformation began at about peak p t conditions of 9 kbar and c 540 560 c in the south and about 7 9 kbar and 490 500 c in the north this continued locally to lower temperature during the second period transport was continuously top to the se crystallographic orientations of white mica and plagioclase give particularly useful information on the kinematic framework in addition data on the ductile behaviour of dolomite and plagioclase can be inferred at c 7 9 kbar dolomite recrystallization starts at 450 480 c and the beginning of plagioclase recrystallization coincides with the oligoclase boundary in general the alpine geodynamic history of the basement cover boundary may be related to continental collision processes between a northerly plate european or brianconnais and a southerly adriatic one the first deformation period possibly reflects subduction of the gneiss sediment boundary toward the wsw to a depth of 31 32 km the second period may be a result of obduction toward the nw followed by late stage uplift most of the basement domes of the eastern tauern window appear as a result of the final stage of the first deformation formed prior to the peak of metamorphism possibly partly influenced by the final collision between the northern and the southern continents

hydrological regimes under the conjunction of westerly and monsoon climates a case investigation in the astore basin northwestern himalaya in a changing climate river basins with limited summer precipitation but abundant snow and glacier melt water are affected severely by reductions and seasonal alterations in annual stream flows however high altitude glacio hydrological observations and investigations to address the linkage between the timing of glacier changes and river runoff fluctuations remain ambiguous particularly in the northwestern himalayan region of pakistan in this context the hydrological regime of the astore basin a sub catchment of the upper indus river basin was comprehensively investigated by employing in situ hydro meteorological observations in combination with satellite remote sensing data two thirds of the annual precipitation in the astore basin falls in winter and spring mainly deposited by westerly winds whereas summer and autumn precipitation deposited by the monsoon and local jet streams accounts for only one third some 14 of the basin area is covered by glaciers and added to the accumulated seasonal snow deposited by westerly circulations this can reach 80 85 of the basin area therefore more than 75 of the annual basin runoff depends on melt water produced by the predominant seasonal snow and glacier ablation the non parametric mann kendall trend test was applied to the whole time series of hydro meteorological data this indicated a lowering of annual and summer mean temperatures during the period 1980 1995 and slight warming during the 1996 2010 period similarly annual winter and summer precipitation and annual mean discharge increased from 1980 to 1995 but in contrast a slight decrease in annual and summer precipitation was observed during the 1996 2010 period however discharge evidence is slight making any increase in this period insignificant in addition the spearman and mann kendall correlation results depict annual stream flow fluctuations during the 1980 2010 decades in the astore river that were predominantly influenced by precipitation variations but not by any alteration in catchment temperatures and so not governed by enhanced glacier ablation and retreat the results of the analysis presented here were also substantiated by satellite remote sensing investigation which points to evidence of stable conditions in the astore basin glaciers during this period

volcanic conduit controls on effusive explosive transitions and the 2010 eruption of merapi volcano indonesia abstract individual volcanoes can produce both effusive and explosive eruptions a transition between these two eruption styles dramatically changes the hazards and can occur either between distinct eruption events or within one eruption episode the causes of these transitions are difficult to determine due to the number of system parameters that can influence whether or not magma fragments in a runaway process we apply a numerical model of magma ascent in a volcanic conduit to isolate and test the effects of key parameters related to magma rheology and system geometry we find that for a given volcanic system parameters that control magma viscosity such as initial water mass fraction initial crystal volume fraction and temperature have the greatest influence on whether or not magma fragments during ascent and erupts explosively we also define a critical condition for the full set of initial parameters under which a transition in eruption style from effusive to explosive or the reverse is more likely to occur under these conditions small heterogeneities in the water or crystal content of the magma or small perturbations to the conduit pressure gradient due to magma chamber overpressure or dome growth or collapse can disrupt the magmatic conditions and cause a transition in eruption style the 2010 vei 4 eruption of merapi volcano included both effusive and explosive phases and was larger by an order of magnitude than its eruptions during the previous century we constrain our model for the merapi system using published literature values and show that between the previous eruption in 2006 and the 2010 eruption the shallow magmatic system at merapi reached critical conditions due to the ascent from depth of a large hotter more volatile rich magma under these critical conditions and according to our model results small changes in the volatile content of the magma small dome collapses subtle changes in degassing rate or the addition of co2 to the magma through decarbonation of the bedrock are all feasible mechanisms for triggering rapid transitions between effusive and explosive activity during the 2010 eruption period

paleomagnetic determination of emplacement temperatures of pyroclastic deposits an under utilized tool paleomagnetic data from lithic clasts collected from mt st helens usa volcan lascar chile volcan de colima mexico and vesuvius italy have been used to determine the emplacement temperature of pyroclastic deposits at these localities and to highlight the usefulness of the paleomagnetic method for determining emplacement temperatures at mt st helens the temperature of the deposits tdep at three sites from the june 12 1980 eruption was found to be 532 c 509 c and 510 570 c respectively one site emplaced on july 22 1980 was emplaced at 577 c these new paleomagnetic temperatures are in good agreement with previously published direct temperature measurements and paleomagnetic estimates lithic clasts from pyroclastic deposits from the 1993 eruption of lascar were fully remagnetized above the respective curie temperatures which yielded a minimum tdep of 397 c samples were also collected from deposits thought to be pyroclastics from the 1913 2004 and 2005 eruptions of colima at colima the sampled clasts were emplaced cold this is consistent with the sampled clasts being from lahar deposits which are common in the area and illustrates the usefulness of the paleomagnetic method for distinguishing different types of deposit tdep of the lower section of the lithic rich pyroclastic flow lrpf from the 472 a d deposits of vesuvius was 280 340 c this is in agreement with other recently published paleomagnetic measurements in contrast the upper section of the lrpf was emplaced at higher temperatures with tdep 520 c this temperature difference is inferred to be the result of different sources of lithic clasts between the upper and lower sections with the upper section containing a greater proportion of vent derived material that was initially hot our studies of four historical pyroclastic deposits demonstrates the usefulness of paleomagnetism for emplacement temperature estimation

fabric transitions in the saxony granulite terrain abstract quartz fabric transitions reported from the saxony granulite terrain and from the nearby ore mountains are interesting because of the changes in the pattern types and the variation in the opening angles of the fabric skeletons a short summary is presented of salient features in research documented in the east german literature between 1961 and 1978 the changes in fabric skeleton with decreasing metamorphic grade are proposed as mainly consequent to the deactivation of prism c glide systems as temperature decreases fabrics indicative of the appearance of the c burgers vector might be diagnostic for deformation in regimes of comparatively high temperatures or low strainrates or for deformation under conditions such that there is a relatively high kinetically effective hydroxyl content in the quartz structure

microstructures and quartz lattice preferred orientations in the eclogite bearing migmatitic gneisses of the d entrecasteaux islands papua new guinea 1 lattice preferred orientations lpo of quartz in gneiss domes of the d entrecasteaux islands woodlark rift shed insight into exhumation of the world s youngest 5 7 ma eclogite bearing terrane at cm yr rates we focus on deformation that affected the terrane as it transited between lower crustal depths and the surface including 1 grain scale deformation mechanisms and 2 style of flow and mode of emplacement of the domes electron backscatter diffraction was used to analyze microstructure and lpos of 37 quartzofeldspathic gneiss samples that enclose meter scale mafic blocks preserving original eclogite facies assemblages during exhumation of the ultrahigh pressure uhp terrane gneisses were retrogressed in the amphibolite facies at lower crustal depths the lpos change from dome cores to carapaces consistent with decreasing deformational temperatures in the relatively chilled outer carapaces of the domes the quartz lpos consist of mostly crossed girdle c axis patterns with some cleft girdle and small circle lpos and record dislocation creep accommodated by mixed slip in the cores of the migmatitic domes a chessboard pattern of subgrains is common and quartz lpos primarily record prism c slip probably at 630 c other microstructures indicate recovery by high temperature grain boundary migration grain boundary mobility was anisotropic leading to strong grain shape fabrics oblique to foliation but not obviously relatable to shear sense evidence for melt present deformation is abundant and microstructures including partially dissolved feldspar grains indicate some deformation by fluid assisted grain boundary diffusion creep lpos in carapace rocks are symmetrical recording flow that was dominantly coaxial we interpret the gneiss domes to have been emplaced into the rift as partially molten diapirs

simulation of block and ash flows and ash cloud surges of the 2010 eruption of merapi volcano with a two layer model a new depth averaged model has been developed for the simulation of both concentrated and dilute pyroclastic currents and their interactions the capability of the model to reproduce a real event is tested for the first time with two well studied eruptive phases of the 2010 eruption of merapi volcano indonesia we show that the model is able to reproduce quite accurately the dynamics of the currents and the characteristics of the deposits thickness extent volume and trajectory the model needs to be tested on other well studied eruptions and the equations could be refined but this new approach is a promising tool for the understanding of pyroclastic currents and for a better prediction of volcanic hazards

a new empirical calibration of the quartz c axis fabric opening angle deformation thermometer abstract the opening angle of quartz c axis fabrics oa is strongly temperature dependent and has proven to be a powerful deformation thermometer for natural metamorphic rocks previous considerations of empirical data have identified a linear correlation between oa and temperature between 250 and 650 c and no correlation above 650 c however possible effects of pressure have not been investigated we expanded the data set of oa versus temperature including data from rocks deformed over 300 1050 c and 2 5 15 kbar disregarding possible effects of pressure the oa temperature relationship can be described by two linear correlations for the intervals 250 650 c and 650 1050 c t c 6 9 o a degrees 48 250 c t 650 c and o a 87 t c 4 6 o a degrees 258 650 c t 1050 c and o a 87 the change on the curve slope of the oa temperature relationship correlates approximately to the low to high quartz transition and to changes in the dynamic recrystallization mechanism from subgrain rotation to grain boundary migration the available data suggest that pressure has a secondary effect accompanying the major temperature dependence of oa which is particularly important for temperatures above 650 c where the correlation between oa and temperature is less pronounced for fixed pressures the oa has logarithmic relationships with temperature over the range 250 1050 c the following thermometer equation is formulated from a multiple regression t c 410 44 ln oa degrees 14 22 p kbar 1272 an uncertainty of 50 c is inherited from the petrological temperature estimates of the natural samples the data suggest the gradual increasing importance of prism c slip relative to slip in quartz with rising temperature under conditions of average geological strain rate and water weakening prism c slip dominates for deformation above 700 c

contrasting patterns of early twenty first century glacier mass change in the himalayas glaciers are among the best terrestrial climate indicators an important water resource in mountains1 2 and a major contributor to global sea level rise3 4 in the hindu kush karakoram himalaya region hkkh a paucity of appropriate glacier data has prevented a comprehensive assessment of current regional mass balance5 however there are indirect evidences of a complex pattern of glacial responses5 8 in reaction to heterogeneous climate change signals9 here we provide the first coherent data set of detailed glacier thickness changes over the hkkh during 2003 2009 by combining satellite laser altimetry and a global elevation model in the eastern central and south western parts of the hkkh glacier wastage is widespread with regional thinning rates up to 0 66 0 09 m a 1 in the jammu kashmir region conversely in the karakoram glaciers are close to balance with only a slight thinning of 0 07 0 04 m a 1 regionally averaged thinning rates under debris mantled ice are similar to those of clean ice despite insulation by debris covers the 2003 2008 specific mass balance for our hkkh study region is 0 21 0 05 m a 1 water equivalent we significantly less negative than the global average of 0 7 m a 1 we for glaciers and ice caps4 10 this difference is mainly an effect of the balanced glacier mass budget in the karakoram the corresponding hkkh sea level contribution is 0 035 0 009 mm a 1 amounting to 1 of the present day sea level rise11 our 2003 2008 mass budget of 12 8 3 5 gt a 1 is more negative than recent satellite gravimetry based estimates of 5 6 gt a 1 over 2003 2010 ref 12 for the mountain catchments of the indus and ganges basins13 the glacier imbalance contributes 3 5 and 2 0 respectively to the annual average river discharge13 and up to 10 for the upper indus basin14

review of the status and mass changes of himalayan karakoram glaciers we present a comprehensive review of the status and changes in glacier length since the 1850s area and mass since the 1960s along the himalayan karakoram hk region and their climate change context a quantitative reliability classification of the field based mass balance series is developed glaciological mass balances agree better with remotely sensed balances when we make an objective systematic exclusion of likely flawed mass balance series the himalayan mean glaciological mass budget was similar to the global average until 2000 and likely less negative after 2000 mass wastage in the himalaya resulted in increasing debris cover the growth of glacial lakes and possibly decreasing ice velocities geodetic measurements indicate nearly balanced mass budgets for karakoram glaciers since the 1970s consistent with the unchanged extent of supraglacial debris cover himalayan glaciers seem to be sensitive to precipitation partly through the albedo feedback on the short wave radiation balance melt contributions from hk glaciers should increase until 2050 and then decrease though a wide range of present day area and volume estimates propagates large uncertainties in the future runoff this review reflects an increasing understanding of hk glaciers and highlights the remaining challenges

prism c slip in the quartzites of the oakhurst mylonite belt california abstract quartz c axis fabrics from 21 amphibolite facies quartzites of the oakhurst mylonite belt california suggest that prism c prism a and basal a slip systems were activated during deformation qualitative two dimensional kinematic models consistent with meso and microscopic shear criteria are constructed based on a regime of combined pure and simple shear in this kinematic framework most of the observed c axis fabric patterns of the oakhurst mylonite belt can be explained if prism c slip was dominant during the early increments of deformation until a transition to dominant basal a slip occurred an apparent relationship between grain size and type of crystallographic fabric is interpreted as resulting from some quartz syntectonic vein quartz having recorded only the latest increments of deformation comparison with the metamorphic evolution of fault zones of similar tectonic origin in california suggests that prism c slip was enhanced by the circulation of hot fluids which hydrolytically weakened quartz and allowed prism c slip to occur at relatively low temperature

the effect of the basal prism mechanism switch on fabric development during plastic deformation of quartzite abstract blacic described a transition from basal a to prism c dislocation glide systems as temperature increased or strain rate decreased in sequences of experiments involving deformation of single crystals of quartz in this paper theoretical aspects of competition between these systems during plastic deformation are discussed it is concluded that the basal prism mechanism switch should have important consequences for the development of crystallographic fabrics during plastic deformation of quartzite and the taylor bishop hill analysis is used in an attempt to predict expected fabric transitions

c slip in quartz from subsolidus deformed granite abstract the slip behaviour of quartz from a granite and granitic veins during subsolidus high temperature conditions 700 800 c of deformation is studied by lattice preferred orientation lpo and microstructural techniques lpos with a point maximum of c axes parallel to the shear direction which is close to the stretching lineation are presented and interpreted with the aid of light and electron microscopy in terms of c as the dominant slip direction during plastic deformation microscopy of such samples reveals the presence of 0001 tilt boundaries and free 0001 burgers vector dislocations in edge orientations a change in lpo in a decreasing temperature environment from c axes parallel to the shear direction to c axes normal to the shear direction documents a fabric transition from the rare c slip to the more common a slip fabric it is concluded that conditions of high temperature and partial pressure of water are required to initiate dominant c slip during deformation at geological strain rates

the 1984 nuee ardente deposits of merapi volcano central java indonesia stratigraphy textural characteristics and transport mechanisms for many centuries merapi volcano has generated hot avalanches of blocks lapilli and ashes derived from the destruction of partially solidified viscous lava domes merapi type nuees ardentes on 15 june 1984 at least four nuees ardentes came down the southwest slope of the merapi the first and the last being responsible for more than 99 of the deposits which are now exposed the first nuee ardente a merapi type nuee ardente was produced by the destruction of the dome travelled 7 km from the crater leaving a measured deposit 2 7 m thick 4 km from the crater near its upper depositional limit regularly increasing to a maximum measured thickness of 12 m at the front of the deposit the lower contact is sharp non erosive with pines still rooted in the underlying paleosol the deposit consists of 50 ash 33 lapilli and 17 blocks with two subpopulations one rosin and one normal and is finespoor with less than 4 of fine ash d finer than 4 the deposit displays reverse population grading of both vesiculated and massive clasts and of the maximum grain size the maximum size significantly increases regularly down current over most of the exposed length of unit 1 and bed thickness increases for the entire length of the deposit the deposit of the second nuee ardente is only 6 21 cm thick and of very limited lateral extent it is a normally graded coarse to fine ash with a finespoor base the third unit consists of fines poor normally graded coarse ash exposed in low amplitude 20 40 cm 12 m wavelength dunes the deposit of the fourth nuee ardente rests in sharp erosive contact on the underlying unit increasing in thickness down flow it consists of transitional coarse and fine grained strata 6 130 c cm thick dipping 5 10 down flow the deposit made up of two subpopulations one rosin and one normal is normally graded over the entire bed but coarsegrained strata are reversely graded the relative content of vesiculated clasts increases up bed in both strata types from 12 at the base to 40 at the top the characteristics of unit 1 suggest that it accumulated from a concentrated suspension of cohesionless solids exhibiting non newtonian behavior where dispersive pressure played an important role in the suspension of the clasts units 2 and 3 were probably deposited from dilute turbulent suspensions whereas the upper unit 4 is a classic example of deposition from a high density turbulent suspension leading to the formation of multiple traction carpets driven by the overlying lower density surge the horizontal distance travelled by a hot rock avalanche may be influenced by its transport mechanism debris flows are mobile on very low slopes as low as 1 whereas grain flows even density modified grain flows require relatively high slopes more than 6 at merapi to maintain their mobility if the present merapi dome were to collapse and produce a debris flow its present volume coupled with the minimal 1 5 km vertical drop could travel a distance ranging between 15 and 30 km however if transport were by grain flow mechanisms the mass could come to rest as it reaches a 5 10 slope

nuees ardentes of 22 november 1994 at merapi volcano java indonesia nuees ardentes associated with dome collapse on 22 november 1994 at merapi volcano traveled to the south southwest as far as 6 5 km and collectively accumulated roughly 2 5 3 million cubic meters of deposits the damaged area comprises 9 5 km2 and is covered by two nuee ardente facies a conventional merapi type valley fill block and ash flow facies and a pyroclastic surge facies the proximal deposits reflect the accumulation of dozens of nuees ardentes with many subsidiary flow units the distal deposits are more simply organized as only a few individual events reached to distances 3 5 km the stratigraphic relationships north of turgo hill indicate that the surge deposits are a facies of particularly mobile nuees ardentes that also deposited channeled block and ash flow facies they further suggest that the surge facies beyond the channel margins correlate laterally with a finer grained sublayer locally developed at the base of the block and ash flow facies eyewitness reports suggest that the emplacement of the block and ash flow facies in the distal part of the boyong river may have followed by a short time interval the destruction and deposition of the surge facies at turgo village the stratigraphy is in accord with the eyewitness reports the surge facies was emplaced by a dilute surge current detached from the same dome collapse nuee ardente that as a separate flow unit subsequently emplaced the distal block and ash deposit in the boyong valley the detachment occurred at higher elevations likely at or above the slope break at about 2000 m elevation this flow separation enabled the surge current to shortcut over the landscape and to emplace its deposit even as the block and ash flow continued its tortuous southward movement in the boyong channel dome collapse nuee ardente activity formed the bulk of the eruption which was accompanied by virtually no significant vertical summit explosive activity

separating snow clean and debris covered ice in the upper indus basin hindukush karakoram himalayas using landsat images between 1998 and 2002 summary the hindukush karakoram himalayan mountains contain some of the largest glaciers of the world and supply melt water from perennial snow and glaciers to the upper indus basin uib upstream of tarbela dam which constitutes greater than 80 of the annual flows and caters to the needs of millions of people in the indus basin it is therefore important to study the response of perennial snow and glaciers in the uib under changing climatic conditions using improved hydrological modeling glacier mass balance and observations of glacier responses however the available glacier inventories and datasets only provide total perennial snow and glacier cover areas despite the fact that snow clean ice and debris covered ice have different melt rates and densities this distinction is vital for improved hydrological modeling and mass balance studies this study therefore presents a separated perennial snow and glacier inventory perennial snow cover on steep slopes perennial snow covered ice clean and debris covered ice based on a semi automated method that combines landsat images and surface slope information in a supervised maximum likelihood classification to map distinct glacier zones followed by manual post processing the accuracy of the presented inventory falls well within the accuracy limits of available snow and glacier inventory products for the entire uib estimates of perennial and or seasonal snow on steep slopes snow covered ice clean and debris covered ice zones are 7238 724 5226 522 4695 469 and 2126 212 km2 respectively thus total snow and glacier cover is 19 285 1928 km2 out of which 12 075 1207 km2 is glacier cover excluding steep slope snow cover equilibrium line altitude ela estimates based on the snow line elevation sle in various watersheds range between 4800 and 5500 m while the accumulation area ratio aar ranges between 7 and 80 0 c isotherms during peak ablation months july and august range between 5500 and 6200 m in various watersheds these outputs can be used as input to hydrological models to estimate spatially variable degree day factors for hydrological modeling to separate glacier and snow melt contributions in river flows and to study glacier mass balance and glacier responses to changing climate

glaciology no ice lost in the karakoram the fate of glaciers in the greater himalaya is widely discussed but poorly known a new measurement in the central karakoram mountain range suggests that glacier mass change in this region contributes to sea level rise nearly 0 05 mm per year less than has been thought

deformation thermometry based on quartz c axis fabrics and recrystallization microstructures a review abstract for quartz rich tectonites two types of deformation thermometer are currently commonly employed 1 the quartz c axis fabric opening angle thermometer that provides an estimate of deformation temperatures when fabrics were locked in during dislocation creep and dynamic recrystallization 2 the quartz recrystallization thermometer that indicates a range of likely deformation temperatures based on observed microstructures and inferred mechanisms of dynamic recrystallization a critically important caveat in applying both thermometers is the assumption that deformation temperature is the primary controlling factor in recrystallization mechanisms and fabric development however fabric opening angles and recrystallization mechanisms are also sensitive to other variables such as strain rate and water weakening in this paper the development of these thermometers is reviewed and their potential sensitivities to competing factors such as temperature strain rate water weakening and in the case of opening angles 3d strain type are discussed examples of the application of these potential thermometers to naturally deformed quartz rich rocks are given and case studies of correlations between deformation temperatures estimated by these thermometers and temperatures of synkinematic metamorphism determined by petrology based thermobarometers are highlighted in the review attention is focused on problems associated with applying these thermometers to natural deformation and examples of such problems are discussed

pure shear dominated transpression and vertical extrusion in a strike slip fault splay from the itapirapua shear zone ribeira belt brazil abstract the itapirapua shear zone is a major ne trending dextral transcurrent zone from the southern ribeira belt brazil which was active during the neoproterozoic brasiliano pan african orogeny related with west gondwana assembly macroscopic sigmoid shaped blocks in its northernmost splay termination present a ne trending subvertical tectonic foliation and subvertical stretching lineation suggesting a transpressional tectonics this paper investigates this splay termination using integration of data from geological mapping thermodynamic modeling microtectonics quartz c axis fabrics kinematic vorticity and finite strain analysis distinct rock assemblages are placed in tectonic contacts along the splay termination including statherian sillimanite biotite paragneiss and granitic orthogneiss apiai mirim complex statherian phyllites bairro dos prestes formation calymmian chlorite epidote actinolite metabasites fazenda velha suite ediacaran phyllites metalimestone and quartzite itaiacoca group and ediacaran granite tres corregos suite isochemical phase diagrams constrain synkinematic metamorphic conditions of 490 510 c and 11 12 5 kbar chlorite biotite phengite phyllite 520 560 c and 9 10 kbar biotite phengite phyllite and 680 690 c and 5 6 kbar sillimanite biotite paragneiss with isothermal decompression paths microstructural evidence suggests that increase in metamorphic temperatures were accompanied by changes in the dominant deformation mechanism in quartz aggregates from subgrain rotation to grain boundary migration recrystallization significant contribution of dissolution precipitation creep indicates water abundant deformational conditions strain ellipsoids are oblate shaped and present ne trending subvertical xy planes and subvertical x axes in agreement with field tectonic fabric quartz c axis fabrics in xz sections of the strain ellipsoid are dominated by symmetrical crossed girdles while the fabrics present dextral asymmetry in horizontal yz sections consistent with macroscopic structural deflection indicating a subvertical vorticity axis vorticity results indicate 48 59 of pure shear contribution the data indicate that strain in the itapirapua shear zone northern termination was accommodated by a pure shear dominated transpression with vertical extrusion at mid crustal conditions which contrasts with a transtensional deformation in the southeastern block

ice ablation and meteorological conditions on the debris covered area of baltoro glacier karakoram pakistan during the recent italian expedition k2 2004 50 years later june july 2004 on baltoro glacier karakoram pakistan glaciological field experiments were carried out on the debris covered area of this high elevation glacier the aim was to investigate the ice ablation and its relations with debris thermal properties and meteorological conditions ablation measurements along the glacier up to about 5000 m and within a dedicated test field were combined with meteorological data from two automatic weather stations located at urdukas 4022 m a s l and at k2 base camp 5033 m a s l in addition temperature measurements of the debris cover at different depth levels along the glacier allowed the calculation of debris surface temperature and of the debris thermal resistance r using the air temperature the local mean lapse rate 0 00758 cm 1 and the measured ablation the degree day factors k at different locations on the glacier were calculated the ice ablation rates were related to debris thickness and elevation they are typically on the order of 4 cm d 1 during the observation period however it was found that the surface topography slope aspect has an influence on the total ablation similar to that of the debris thickness thermal resistance of the debris cover and its distribution over the glacier were estimated finally a best guess estimate of the total meltwater production was calculated from available climate data

very rapid cooling of the energetic pyroclastic density currents associated with the 5 november 2010 merapi eruption indonesia abstract understanding the thermal behavior of pyroclastic density currents pdcs is crucial for forecasting impact scenarios for exposed populations as it affects their lethality and destructiveness here we report the emplacement temperatures of pdc deposits produced during the paroxysmal explosive eruption of merapi central java on 5 november 2010 based on the reflectance of entombed charcoal fragments this event was anomalously explosive for merapi and destroyed the summit dome that had been rapidly growing with partial collapses and associated pdcs since october 26 results show mean reflectance values mainly between 0 17 and 0 41 these new data provide a minimum temperature of the flow of 240 320 c consistent with previous estimations determined from independent field engineering and medical observations published in the literature for this eruption a few charcoal fragments recorded higher values suggestive of temperatures up to 450 c and we suggest that this is due to the thermal disequilibrium of the deposits with larger block size clasts being much hotter than the surrounding ash matrix charring temperatures show no major differences between proximal and distal pdc deposits and are significantly lower than those that may be associated with a fast growing dome dominated by dense and vitric non vesicular rocks we therefore infer that the decrease in temperature from that at fragmentation 900 c occurred in the very initial part of the current

a joint analysis of river runoff and meteorological forcing in the karakoram upper indus basin satellite geodetic altimetry investigations in the karakoram have indicated slight mass gain or loss of the glaciers during the early part of 21st century equivalent discharge in the upper indus basin uib due to these mass changes has been estimated at 5 to 10 of mean annual flow however satellite altimetry and geodetic glacier mass estimates in the extreme topography of the karakoram have not yet been counter validated by hydrological analysis therefore we present a first cross validation of three to five decades of river flow data from the three major watersheds in the karakoram with matching series of monthly precipitation temperature and evaporation provided by six atmospheric reanalysis products for 1979 2014 the analyses suggest that in most cases river flows have been increasing steadily from the end of the 1960 s and 1970 s to the middle of the 1990 s and have stabilized or are in decline since then hunza watershed in karakoram west shows consistently declining flows over the first half of the analysis period and stable flows during the second half for most of the summer melting season suggesting mass accumulation rising river flows in the shyok and shigar watersheds followed by stabilizing or slightly declining flows from 1995 onward can be explained by consistently increasing precipitation during the first half of the analysis period and successive stabilization or minor decline thereof flow data do not necessarily suggest considerable loss or gain of glacial mass in the karakoram during the late 90 s and early 2000 s as suggested by satellite based altimetry studies

rheology of welding inversion of field constraints at present the mechanisms and rheological behaviour of pyroclastic deposits during welding and compaction are poorly understood here we explore the extent to which the rheological properties of pyroclastic deposits are constrained by physical property distributions in welded ignimbrite physical properties of samples from a 20 m section of the bandelier tuff new mexico are used as proxies for strain the observed strain et is ascribed to a combination of a time dependent viscous compaction ev and a time independent mechanical compaction em described by

effects of chemical environment on dislocation creep of quartzite the water related chemical parameter that affects dislocation creep in quartzite has been determined from variations in sample strength and microstructure with chemical environment in buffered deformation and hydrostatic annealing experiments samples were weld sealed in double capsules and were buffered using solid oxygen buffers agcl or co2 black hills quartzite was deformed at 900 c and 1 5 10 5s 1 two samples were deformed at 1700 mpa confining pressure at constant and with and varying over 8 and 15 orders of magnitude respectively both samples deformed by climb accommodated dislocation creep with flow stresses of 300 mpa two additional samples were deformed at 700 mpa at constant lower than for the 1700 mpa samples with varying over 2 orders of magnitude both samples faulted with a peak strength of 800 mpa these four experiments suggest no dependence of dislocation creep strength on or instead a strong dependence of strength on is inferred previously deformed samples of heavitree quartzite were hydrostatically annealed for 4 days at 800 c and 1200 or 500 mpa confining pressure varying and over 2 5 and 1 order of magnitude respectively the microstructures of these samples show increased rates of dislocation climb and grain boundary migration with increasing but no dependence on these buffered experiments indicate that dislocation creep is affected by alone and suggest that the exponent for the term in the power law creep flow law is 2

the merapi 2010 eruption an interdisciplinary impact assessment methodology for studying pyroclastic density current dynamics abstract the large explosive eruption of merapi volcano indonesia in 2010 presented a key and rare opportunity to study the impacts of a major explosive eruption in a densely populated area pyroclastic density currents pdcs produced throughout the 2010 eruption were unusually destructive causing near complete devastation across a 22 km 2 swath of the densely populated southern flanks and casualties to the end of their runout at 15 5 km from the volcano the majority 120 of the more than 200 fatalities occurred more than 12 km from the volcano where many people were caught in pdcs as they were evacuating the 2010 eruption vei 4 exhibited a range of pdc behaviour in a complex multi stage event that marked a change in eruption behaviour at merapi being the first eruption of this magnitude and style since 1872 this shift in style may mark a change in regime and so understanding the potential impact of such large explosive eruptions is essential for future risk assessment at merapi we describe a new impact assessment methodology that allowed us to collect important empirical geological damage and casualty information and reconstruct impact dynamics associated with the pdcs in contrast to previous pdc impact studies we combined remote field laboratory and gis assessments and were able to enter the affected areas safely and before their disturbance by rains or human activity by integrating the results of our geological damage and medical studies we could reconstruct the spatial and temporal dynamics of the pdcs and their main hazard characteristics our interdisciplinary methods and preliminary findings are discussed here in the areas damaged by pdcs we used empirical damage data and calculations of material and structural resistance to lateral force to estimate approximate dynamic pressures dynamic pressures associated with the 5 november paroxysm exceeded 15 kpa more than 6 km from source and rapidly attenuated over a distance of less than 1 km at the end of the pdc runouts analysis of thermal indicators such as deformed plastic and correlation with information on burns injuries and fires provided estimates of ambient temperatures associated with the pdcs even at the relatively low temperatures estimated for the pdcs 200 300 c they were lethal to people inside as well as outside buildings in part because of the building design that enabled the pdcs to rapidly infiltrate inside such detailed quantitative data can be used to support numerical pdc and impact modelling and risk assessment at dome forming volcanoes providing an improved understanding of the complexity of pdcs and their associated impacts on exposed populations

historical eruptions of merapi volcano central java indonesia 1768 1998 abstract information on merapi eruptive activity is scattered and much is remotely located a concise and well documented summary of this activity has been long needed to assist researchers and hazard mitigation efforts and the aim of this paper is to synthesize information from the mid 1700s to the present a descriptive chronology is given with an abbreviated chronology in a table that summarizes events by year assigns preliminary volcanic explosivity index vei ratings and hartmann classifications and provides key references the history of volcano monitoring is also outlined the study reveals that a major difference in eruption style exists between the twentieth and nineteenth centuries although the periodicity between larger events seems about the same during the twentieth century activity has comprised mainly the effusive growth of viscous lava domes and lava tongues with occasional gravitational collapses of parts of oversteepened domes to produce the nuees ardentes commonly defined as merapi type in the 1800s however explosive eruptions of relatively large size occurred to vei 4 and some associated fountain collapse nuees ardentes were larger and farther reaching than any produced in the twentieth century these events may also be regarded as typical eruptions for merapi the nineteenth century activity is consistent with the long term pattern of one relatively large event every one or two centuries based on the long term eruptive record deduced by others from volcanic stratigraphy it is uncertain whether or not a recurrence time model continues to apply to merapi but if so merapi could soon be due for another large event and its occurrence with only modest or inadequately appreciated precursors could lead to a disaster unprecedented in merapi s history because the area around the volcano is now much more densely populated

spatial distribution of debris thickness and melting from remote sensing and meteorological data at debris covered baltoro glacier karakoram pakistan a distributed surface energy balance study was performed to determine sub debris ablation across a large part of baltoro glacier a wide debris covered glacier in the karakoram range pakistan the study area is 124 km 2 the study aimed primarily at analyzing the influence of debris thickness on the melt distribution the spatial distribution of the physical and thermal characteristics of the debris was calculated from remote sensing aster image and field data meteorological data from an automatic weather station at urdukas 4022 m a s l located adjacent to baltoro glacier on a lateral moraine were used to calculate the spatial distribution of energy available for melting during the period 1 15 july 2004 the model performance was evaluated by comparisons with field measurements for the same period the model is reliable in predicting ablation over wide debris covered areas it underestimates melt rates over highly crevassed areas and water ponds with a high variability of the debris thickness distribution in the vicinity and over areas with very low debris thickness 0 03 m we also examined the spatial distribution of the energy balance components global radiation and surface temperature over the study area the results allow us to quantify for the study period a meltwater production of 0 058 km 3

physical properties of the wais divide ice core the wais west antarctic ice sheet divide deep ice core was recently completed to a total depth of 3405 m ending 50 m above the bed investigation of the visual stratigraphy and grain characteristics indicates that the ice column at the drilling location is undisturbed by any large scale overturning or discontinuity the climate record developed from this core is therefore likely to be continuous and robust measured grain growth rates recrystallization characteristics and grain size response at climate transitions fit within current understanding significant impurity control on grain size is indicated from correlation analysis between impurity loading and grain size bubble number densities and bubble sizes and shapes are presented through the full extent of the bubbly ice where bubble elongation is observed the direction of elongation is preferentially parallel to the trace of the basal 0001 plane preferred crystallographic orientation of grains is present in the shallowest samples measured and increases with depth progressing to a vertical girdle pattern that tightens to a vertical single maximum fabric this single maximum fabric switches into multiple maxima as the grain size increases rapidly in the deepest warmest ice a strong dependence of the fabric on the impurity mediated grain size is apparent in the deepest samples

a new estimate of the conditions for transition from basal a to prism c slip in naturally deformed quartz abstract quartz c axis fabrics of naturally deformed quartz in metacherts from the ryoke metamorphic belt in the yanai district southwestern japan suggest that the prism c prism a and basal a slip systems were activated during the plastic deformation under high temperature metamorphic conditions with increasing temperature quartz c axis fabric patterns change from girdle type through x maximum with a faint crossed girdle to x maximum the dominant orientation of subgrain boundaries in the quartz also changes from prism to basal with increasing temperature closely correlated with the change in quartz c axis fabric the fabric transition is also accompanied by an abrupt increase of recrystallized quartz grain size moreover observations with transmission electron microscopy tem clearly identify the dominant activation of c slip through the presence of basal subgrain boundaries and free dislocations with the 0001 burgers vector in the quartz from the metachert samples exhibiting x maximum c axis fabric based on these observations it is concluded that the mechanism switch from basal a to prism c slip systems occurred with increasing temperature in the metacherts the transition temperature is petrologically estimated to be ca 550 600 c at the natural strain rate

earthquake induced variations in extrusion rate a numerical modeling approach to the 2006 eruption of merapi volcano indonesia abstract extrusion rates during lava dome building eruptions are variable and eruption sequences at these volcanoes generally have multiple phases merapi volcano java indonesia exemplifies this common style of activity merapi is one of indonesia s most active volcanoes and during the 20th and early 21st centuries effusive activity has been characterized by long periods of very slow

the 17 july 1999 block and ash flow baf at colima volcano new insights on volcanic granular flows from textural analysis abstract on july 17 1999 a strong explosion occurred at colima volcano mexico that produced a 10 km high eruptive column the partial column collapse originated a block and ash flow baf that flowed to the south along the san antonio and montegrande ravines travelling 3 3 km from the volcano summit the flow filled the ravines with a volume estimated at 7 9 105 m3 the erosion of these deposits occurred between 1999 and 2002 time of sampling providing excellent longitudinal outcrops that allowed their detailed textural study the study was carried out by means of quantitative textural analysis 1 rosiwal intersections for carrying out vertical granulometric profiles 2 total grain size analysis from 11 to 9 and 3 fourier and fractal analysis of the particle morphology grain size and morphometric parameters obtained with these methods were used to identify vertical and longitudinal variation patterns in the baf deposit the grain size variations allowed to infer the main particle segregation mechanisms that acted during transport and deposition of the studied bafs the two methods used for studying the particle shape morphologies yielded results with different accuracy and reliability in particular fractal analyses have been found to be the most effective in describing the particle support mechanisms that acted during transport and deposition of the studied bafs the results highlight the importance of the information obtained by means of these techniques and provide new insights in transportation and deposition mechanisms of bafs

a reevaluation of the snowmelt and glacial melt in river flows within upper indus basin and its significance in a changing climate summary the hydrograph separation method previously proposed to quantify base flow seasonal snowmelt and glacial melt components in river flows within upper indus basin underestimates glacial melt component this is particularly limiting for highly glacierized watersheds the limitation has been corrected by a further refinement of the method the results with the refined procedure are highly consistent with the physical characteristics such as hypsometry and glacier extents of the watershed even though the method itself is completely independent of the physical characteristics of the watershed where it is applied glacial melt far outweigh snowmelt in the rivers draining the karakoram and zanskar ranges in the karakoram on an annualized basis glacial melt proportion varies from 43 to 50 whereas snowmelt varies from 27 to 31 on the other hand snowmelt dominates over glacial melt in the rivers draining the western greater himalayas and the hindu kush here snowmelt percentage in river discharge varies from 31 to 53 whereas that of glacial melt ranges from 16 to 30 in the main stem of upper indus river snowmelt fraction in most cases is slightly greater than the glacial melt fraction in the main stem snowmelt percentage ranges from 35 to 44 whereas glacial melt percentage ranges from 25 to 36 upper indus river just upstream of tarbela reservoir carries annual flows constituted of 70 melt water of which 26 is contributed by glacial melts and 44 by snowmelts we also show that during the later part of twentieth century and continuing into the early part of twenty first century glacial melt contributions to river discharge has decreased compared to the previous decades this phenomenon can be ascribed to either basin wide loss of glacial mass in the recent decades in the elevation range from where most of the glacial melt originates or glacier growth and stability due to either reduction in energy inputs or increase in precipitation or both at the high altitude bands wherefrom glacial melt water originates

the evolution of a late variscan high t low p region the southeastern margin of the bohemian massif a characteristic feature of the moldanubian part of the central european variscides is late orogenic high t low p metamorphism its past history and the possible reasons for this metamorphism are highlighted by the tectonometamorphic development at the south eastern margin of the bohemian massif during the variscan orogeny at ca 340 ma two different crustal segments were juxtaposed by thrusting the drosendorf unit on top of the monotonous unit this probably marks a collisional event that is widespread in the southeastern moldanubian zone the collision was followed by crustal uplift accompanied by strong heating in the lowermost structural unit monotonous unit during the subsequent orogenic collapse the moldanubian nappe pile was thrust over parts of the moravo silesian terrane a late stage of crustal extension under greenschist facies conditions is linked with pluton emplacement in general magmatic underplating as well as delamination of the lithospheric mantle explains the high t low p metamorphism and the large scale plutonism in the southeastern moldanubian zone

metamorphism of the central anatolian crystalline complex turkey influence of orogen normal collision vs wrench dominated tectonics on p t t paths the central anatolian crystalline complex cacc is a microcontinent in the alpine himalayan belt it has previously been considered as a coherent structural entity but although the entire cacc is comprised of similar rocks primarily metasedimentary rocks and granitoids it consists of at least four tectonic blocks characterized by different p t t paths these blocks are the kirsehir north west akdag north east nigde south and aksaray west massifs the northern massifs experienced thrusting and folding during collision and were slowly exhumed by erosion metamorphic rocks are characterized by clockwise p t paths at moderate p t and local low p high t lp ht overprinting in the highest grade rocks apatite fission track ages are eocene to oligocene 47 32 ma the aksaray block represents the hot shallow mid crust of a late cretaceous early tertiary arc it is dominated by intrusions rare metapelitic rocks record low p 4 kbar regional metamorphism overprinted by lp ht contact metamorphism apatite fission track ages are 50 45 ma the nigde massif is different from the other cacc blocks because it evolved as a core complex in a wrench dominated setting it is characterized by clockwise p t paths at moderate p t followed by widespread lp ht metamorphism apatite fission track ages are miocene 12 9 ma significantly younger than those in the northern massifs nigde rocks resided in the mid crust at a time when the rest of the cacc was at or near the earth s surface variations in p t t and tectonic histories especially timing of exhumation between the northern and southern cacc reflect the difference between head on collision vs mid crustal wrenching

neoarchean tectonics insight from the baijiafen ductile shear zone eastern anshan liaoning province ne china abstract the north china craton is one of the major archean to paleoproterozoic cratons in the world and oldest craton in china which preserves a large amount of ancient basement and abundant structures showing the early earth tectonics the controversy over the archean tectonic regimes has lasted several decades centering around horizontal and vertical tectonics the two classical tectonic models for archean times thus more studies of the early crustal growth and tectonic evolution are requisite for better understanding geodynamic regimes in the early precambrian this study provides an example for revealing of archean tectonics the nwn trending ene dipping baijiafen ductile shear zone is located in the eastern anshan of the northeastern north china craton and mainly comprises two types of gneisses including the chentaigou porphyritic granitic gneiss and the baijiafen trondhjemitic gneiss in this study we have carried out a detailed study on the macrostructure microstructure and fabric characteristics of the two main types of deformed gneisses within the shear zone the ribbon structures formed by intensely elongated quartz grains are widespread in these gneisses well developed mineral stretching lineations and asymmetric fabrics indicate an ese directed downward shearing the quartz c axis fabric patterns obtained by electron backscatter diffraction technique imply low to middle temperature non coaxial deformation with active rhomb a slip and basal a slip deformation behaviors of minerals and quartz crystallographic preferred orientations demonstrate that the rocks underwent mylonitization at a temperature of 400 500 c under greenschist facies metamorphic conditions dislocation creep is the main rock deformation mechanism within the shear zone finite strain measurement results suggest that the strain types of the shear zone are generally related to elongate plane deformation and the tectonites change from l s to ls type across the shear zone the strain intensity increases obviously towards east and the baijiafen gneiss unit is located within the high strain zone kinematic vorticity values of gneisses indicate that the deformed rocks were produced by steady state simple shear dominated general shear based on abundant structural evidence and previous studies we infer that the deformation of the baijiafen ductile shear zone may have resulted from the downward adjoining rock flow during the sagduction of the banded iron formations and synchronous archean granite dome emplacement supporting a vertical tectonic regime in archean times

textural and mineral chemistry constraints on evolution of merapi volcano indonesia abstract we analyze and compare the textures of merapi lavas basalts and basaltic andesites ranging in age from proto merapi through modern activity with the goal of gaining insights on the temporal evolution of merapi s magmatic system analysis of textural parameters such as phenocryst and microphenocryst crystallinity coupled with crystal size distribution theory provides information about the storage and transport of magmas we combine textural analyses with geochemical investigations for a comprehensive comparison of erupted lavas over time the chemical analyses identify crystal growth processes in magma chambers and underline differences between sample groups our work suggests the occurrence of two distinct histories presumably associated with at least two generally distinct types of rheological behaviors and storage transport systems these behaviors are associated with different plagioclase growth patterns with both groups influenced by late stage shallow decompression degassing induced microlite crystallization both groups contain amphibole crystals that indicate an early period of mid crustal to deep crustal storage of water rich magmas dome lavas from the 20th century eruptive activity indicate quasi steady state nucleation and growth evolution interspersed with episodes of reheating and textural coarsening suggesting residence in magma storage at multiple depths both 10 km and

the role of dynamic recrystallization in the development of lattice preferred orientations in experimentally deformed quartz aggregates abstract experiments on coaxially deformed quartz aggregates show that when dynamic recrystallization involves grain size reduction the lattice preferred orientation lpo of the recrystallized grains depends on the recrystallization mechanism at low temperatures and fast strain rates strain induced grain boundary migration recrystallization favors growth of grains oriented poorly for slip on the basal and prism planes resulting in an lpo of c axes parallel to the 1 direction at higher temperatures or slower strain rates progressive subgrain rotation produces recrystallized grains which inherit the small circle girdle lpo of their deformed host grains and which continue to re orient by slip at even higher temperatures and slower strain rates progressive subgrain rotation is accompanied by rapid grain boundary migration which does not favor grains of any particular orientation thus the lpo is again similar to that of non recrystallized grains in contrast when dynamic recrystallization involves grain growth driven by surface energy reduction a strong lpo of c axes parallel to 1 develops during grain growth but then evolves with increasing strain toward a small circle girdle the correlation of lpos with recrystallization mechanisms has important implications for the assumption of homogeneous strain in theoretical models of lpos and for interpreting natural lpos in recrystallized rocks

rising river flows and glacial mass balance in central karakoram summary field observations and geodetic measurements suggest that in the central part of the karakoram mountains glaciers are either stable or expanding since 1990 in sharp contrast to glacier retreats that are prevalent in the himalayas and adjoining high altitude terrains of central asia decreased discharge in the rivers originating from karakoram is cited as a supporting evidence of this somewhat anomalous phenomenon here in contrary to those citations we show that river discharge during the melting season of the glaciers in central karakoram has increased from 1985 to 2010 we have implemented a sophisticated statistical procedure involving non parametric tests combined with a benchmark smoothing technique that has proven to be a powerful method for empirical trend analysis to remove the stochastic component from the trend component in a time series melt water from winter snows is the dominant constituent of june and july flows glacial melts predominantly contribute to august and partially to september flows which are controlled by monsoonal snowfall too at elevations approximately 3500 m for all four summer months flows increased from 1985 to 2000 august flows which actually reflect the states of the glaciers have continued to rise steadily after 2000 at the same rate as those did for the period 1985 2000 however the rising trends of june and july flows changed to slightly declining trends from 2000 to 2010 these trends most likely indicate drop in winter snowfall over karakoram and do not provide direct indications about the states of the glaciers the rising trend of august discharge is due to change in glacial storage at a steadily decreasing rate of approximately 0 04 0 05 mm day year for the period 1985 2010 this rate is nearly equal to the rate of increase in precipitation during the summer months over karakoram mountains in recent decades as determined from the era 40 and gpcp precipitation datasets thereby this is most plausibly why the glacial mass balance in central karakoram is nearly neutral the rising river flows accompanying non negative glacier mass balance are consistent with predicted future river flows derived from hydrologic modeling coupled with a climate projection suggesting increasing temperature and precipitation with unchanged glacier covers this investigation reconciles two apparently contradictory observations namely rising river flows and either zero or slightly positive mass balance of central karakoram glaciers

diachronous deformation along the base of the himalayan metamorphic core west central nepal geologic mapping combined with microstructural and geochronologic analyses from the lower himalayan metamorphic core in west central nepal record along strike similarity in flow style despite variability in the timing of metamorphism and deformation the main central thrust zone at the base of the himalayan metamorphic core varies in thickness tectonostratigraphy and metamorphic gradient along the 250 km of strike length studied in situ u th pb geochronology of monazite sampled from an along strike transect at the top of the high strain zone records eocene oligocene prograde metamorphism followed by miocene retrograde metamorphism the timing of prograde and retrograde metamorphism and the muscovite 40 ar 39 ar dates gradually decrease along strike from northwest to southeast this age trend is punctuated by an abrupt 3 8 m y decrease in the age of prograde and retrograde metamorphism and muscovite 40 ar 39 ar dates near the marsyandi river in central nepal quartz crystallographic preferred orientation fabrics from a parallel transect along the base of the high strain zone document similar flow style at 440 c in central nepal muscovite 40 ar 39 ar ages interpreted to approximate the age of deformation at this structural level decrease from ca 7 to 4 ma along strike from northwest to southeast diachronous deformation and metamorphism along strike in west central nepal demonstrate the necessity of incorporating more than a single transect into tectonic models along strike tectonometamorphic variability in west central nepal spatially corresponds to faults in the indian basement bounding the subsurface faizabad ridge highlighting the possible influence of inherited basement faults on the geometry of the basal himalayan detachment the main himalayan thrust as well as the tectonic evolution of the structurally overlying himalayan metamorphic core this study highlights the potential influence of inherited structures on the overlying orogenic wedge and the probability of along strike diachroneity of deformation in the himalaya

model of successive granite sheet emplacement in transtensional setting integrated microstructural and anisotropy of magnetic susceptibility study 1 this study presents a model of successive emplacement of three granite plutons in transtensional deformation regime controlled by the preextensional synconvergent history of the lower and middle crust in the central vosges mountains france the complex compressional orogenic structure recorded a vertical exhumation related fabric in midcrustal levels which was overprinted by the regional extension three successively emplaced granite sheets exploited the inherited vertical anisotropy obliquely oriented with respect to the applied tensile stress this progressive opening of original steep fabric leads to the sequential generation of free spaces toward the south and emplacement and deformation of granite sheets repeated granite intrusions are responsible for reheating of southern margins of the already partially solidified granites which became reactivated under lower ambient thermal conditions related to overall 6 ma cooling of rapidly exhumed crust the results of anisotropy of magnetic susceptibility ams fabric modeling suggest a highly partitioned oblique extension divided into pure shear dominated deformation close to the central and northern margins of intrusions and wrench dominated shear along the southern margins the ams modeling suggests the importance of overprinting of the intrusive fabrics by the transtensional deformation

field observations and surface characteristics of pristine block and ash flow deposits from the 2006 eruption of merapi volcano java indonesia abstract a series of pristine block and ash flow deposits from the may june 2006 eruption of merapi represent an exceptional record of small volume pyroclastic flows generated by gravitational lava dome collapses over a period of about two months the deposits form nine overlapping lobes reaching 7 km from the summit in the gendol river valley on the volcano s southern flank which were produced by successive flows generated during and after the major dome collapse event on june 14 both single pulse post june 14 events and multiple pulse pyroclastic flows generated by sustained dome collapses on june 14 are recognised and three types of deposits spread over an area of 4 7 km are distinguished totalling 13 3 10 6 m 3 1 valley confined basal avalanche deposits 11 7 10 6 m 3 in the gendol river valley 2 overbank pyroclastic flow and associated surge deposits 1 4 10 6 m 3 where parts of the basal avalanche spread laterally onto interfluves and were subsequently channeled into the surrounding river valleys and 3 dilute ash cloud surge deposits 0 2 10 6 m 3 along valley margins variations in the distribution surface morphology and lithology of the deposits are related to the source materials involved in individual pyroclastic flow forming events and varying modes of transport and deposition of the different flows inferred flow velocities of the largest block and ash flows generated on june 14 vary from 43 8 13 5 m s for the basal avalanche and from 62 6 24 2 m s for the ash cloud surge the minimum temperatures range from 400 c for the basal avalanche to 165 c for the overlying ash cloud due to the potential of being re channeled into adjacent river valleys and flowing laterally away from the main river channel the overbank pyroclastic flows are considered the most hazardous part of the block and ash flow system the conditions that lead to their development during flow transport and deposition must be taken into account when assessing future pyroclastic flow hazards at merapi and similar volcanoes elsewhere

vegetation dieback as a proxy for temperature within a wet pyroclastic density current a novel experiment and observations from the 6th of august 2012 tongariro eruption abstract the 6th of august 2012 eruption of te maari mt tongariro new zealand generated wet pyroclastic density currents pdcs which caused widespread dieback of vegetation singed brown foliage in their path an absence of significant charcoal formation suggests that pdc temperatures were mostly below 250 c textural evidence for liquid water being present in the matrices during emplacement vesicles suggests that temperatures were

emplacement temperatures of the november 22 1994 nuee ardente deposits merapi volcano java abstract a study of emplacement temperatures was carried out for the largest of the 22 november 1994 nuee ardente deposits at merapi volcano based mainly on the response of plastic and woody materials subjected to the hot pyroclastic current and the deposits and to some extent on eyewitness observations the study emphasizes the turgo kaliurang area in the distal part of the area affected by the nuee ardente where nearly 100 casualties occurred the term nuee ardente as used here includes channeled block and ash flows and associated ash clouds of surge and fallout origins the emplacement temperature of the 8 m thick channeled block and ash deposit was relatively high 550 c based mainly on eyewitness reports of visual thermal radiance emplacement temperatures for ash cloud deposits a few cm thick were deduced from polymer objects collected at turgo and kaliurang most polymers do not display a sharp melting range but polyethylene terephthalate used in water bottles melts between 245 and 265 c and parts of the bottles that had been deformed during fabrication molding turn a milky color at 200 c the experimental evidence suggests that deposits in the turgo area briefly achieved a maximum temperature near 300 c whereas those near kaliurang were

prism and basal plane parallel subgrain boundaries in quartz a microstructural geothermobarometer empirical data on quartz subgrain patterns from various metamorphic rocks show that at least up to 10 kbar in the stability field of low quartz prismatic subgrain boundaries are dominant whereas basal subgrain boundaries are not developed in the high quartz stability field both prismatic and basal subgrain boundaries occur and form typical rectangular chessboard patterns the likely reason behind the different occurrence of these subgrain patterns is that in high quartz prismatic glide becomes as easy as or probably even easier than basal glide the two types of subgrain patterns can be clearly distinguished by optical microscopy consequently the occurrence of chessboard subgrain patterns in quartz represents a practicable geothermobarometer the possibilities of its application are far reaching and include the specification of deformation conditions at high grade metamorphism the recognition of syntectonic intrusions and the distinction between pluton emplacement at lower and at higher crustal levels

glaciological characteristics of the ablation zone of baltoro glacier karakoram pakistan baltoro glacier in the karakoram pakistan is one of the world s largest valley glaciers it drains an area of about 1500 km 2 and is 60km long in 2004 an italian german expedition carried out a glaciological field program on the ablation zone of the glacier focusing on the ablation conditions and the dynamic state of the glacier as baltoro glacier is a debris covered glacier ice ablation also depends on the debris properties stake measurements of ice ablation and debris cover in combination with meteorological data from automatic weather stations close by have been used to determine the local melt conditions results from these calculations have been combined with an analysis of different classes of surface cover and information about precipitation using remote sensing techniques in order to calculate mass fluxes for the upper part of baltoro glacier the dynamic state of the glacier has been investigated by gps based surface velocity measurements along the stake network a comparison of these short term measurements during the melt season with surface velocities computed from feature tracking of satellite images shows a high seasonal variability of the ice motion we have shown that this variability is up to 100 of the annual mean velocity on the basis of these investigations the mass fluxes at the concordia cross section have been quantified this approach can now be used together with the ablation calculations to reconstruct the variability of glacier extent and volume in the past using available climate data from the central karakoram from the comparison of historical measurements and photographs it is shown that the snout of baltoro glacier is oscillating back and forth a couple of hundred metres otherwise it seems not to react with the same magnitude as other glaciers to the climatic change elevation changes at concordia are a few tens of metres at the most

relationships between displacement and distortion in orogens linking the himalayan foreland and hinterland in central nepal greater himalayan sequence rocks exposed in the manaslu himal chuli himalaya can be separated into distinct upper and lower parts deformation recorded in both parts occurred at temperatures ranging between 450 c and 640 c and is characterized by almost equal coaxial and noncoaxial components across the upper greater himalayan sequence peak metamorphic temperatures are essentially isothermal whereas corresponding metamorphic pressure estimates across the same section decrease downward with an apparent gradient of 620 bars km in the lower greater himalayan sequence however both metamorphic pressure and temperature decrease with structural depth the abnormal pressure gradient in the upper greater himalayan sequence is attributed to 50 vertical thinning during southward displacement while the inverted gradient in the lower portion is interpreted to be the result of coeval exhumation and downward expansion of the main central thrust shear zone and the progressive incorporation of more rock into the greater himalayan sequence deformation in the upper portion of the greater himalayan sequence was characterized by extending flow i e extension in the direction of flow whereas deformation in its lower portion was characterized by compressing flow i e compression in the direction of flow extending flow is a distinctive feature of displacement and distortion in deep orogenic hinterlands while compressing flow is emblematic of displacement and distortion in orogenic foreland regions the transition between the upper and lower parts of the greater himalayan sequence therefore represents a fundamental transition between hinterland style deformation involving processes such as lateral midcrustal flow and foreland style deformation involving critical taper thrust fold wedge development

structural style and geochronology of ductile shear zones in the western north qinling orogenic belt central china implications for paleozoic orogeny in the central china orogeny abstract the qinling orogen which was formed by long lived subduction and collision between the north and south china blocks can be divided into the south qinling orogenic belt sqob and the north qinling orogenic belt nqob by the shangdan suture zone orogen scale shear zones developed on the boundaries within the nqob can be used to enhance our understanding of collisional orogeny that occurred during the paleozoic in the qinling orogen previous studies have identified several ductile shear zones on boundaries between different lithotectonic units in the eastern nqob however ductile shear zones related to orogenic processes in the western nqob have attracted relatively little attention herein we present structural and chronological data for the ductile shear zones in the tianshui region western nqob three sub parallel ductile shear zones dsz 1 dsz 2 and dsz 3 are recognised in the southern qinling complex or as boundaries between the qinling complex and adjacent lithotectonic units in the huamiao area tianshui city microstructural and fabric analyses indicate that these shear zones have kinematics of transpressive sinistral strike slip zircon u pb and 40ar 39ar dating data suggest that these ductile shear zones experienced a prolonged period of deformation from 420 to 370 ma during exhumation which was related to oblique convergence between the sqob and the nqob combining with the synchronous xinyang yuanlong dextral shear zone in the northern qinling complex we suggest that the transpressive sinistral shearing and dextral transpressive ductile shearing on both sides of the qinling complex subjected it to orogen parallel oblique slip extrusion during the middle paleozoic our results together with previously published data in the eastern nqob indicate the occurrence of orogen scale strike slip shearing along the whole nqob during the paleozoic orogeny

slight mass gain of karakoram glaciers in the early twenty first century the mass balance of hindu kush karakoram himalaya glaciers has been debated partly because of a severe lack of observations from the region an analysis of the regional mass balance of karakoram glaciers by comparison of digital elevation models from 1999 to 2008 reveals a small glacier mass gain in the area

transient effects of magma ascent dynamics along a geometrically variable dome feeding conduit abstract the transient dynamics of magma ascent during dome forming eruptions were investigated and the effects of magma chamber pressure perturbations on eruption rate are illustrated the numerical model domeflow developed by the authors for this work is applied to the problem domeflow is a transient 1 5d isothermal two phase flow model of magma ascent through an axisymmetric conduit of variable radius which accounts for gas exsolution bubble growth crystallization induced by degassing permeable gas loss through overlying magma and through conduit walls as well as viscosity changes due to crystallization and degassing for runs in which chamber pressure increases the time required to reach the new steady state transition time is a complex function of the pressure perturbation while for decreasing chamber pressure transition time is a monotonic function of the magnitude of the pressure perturbation the transition to the new steady state is mainly controlled by magma compressibility travel time time required for one parcel of magma to travel from chamber to surface and the time over which the pressure perturbation occurs results of many runs 300 were analyzed using dimensional analysis to reveal a general relationship which predicts the temporal evolution of magma effusion rate for a given sudden increase in chamber pressure the product of the change in steady state extrusion rate and the time required to reach the new steady state is linearly proportional to the normalized change in chamber pressure the volume of the conduit and the ratio of top and bottom conduit radii and inversely proportional to the cubic root of volatile fraction this relationship is used to interpret observed variations in two ongoing dome building eruptions the soufriere hills volcano montserrat and merapi volcano indonesia

quantifying geometrically necessary dislocations in quartz using hr ebsd application to chessboard subgrain boundaries abstract this study presents the first use of high angular resolution electron backscatter diffraction hr ebsd to quantitatively characterise geometrically necessary dislocations in quartz subgrain structures hr ebsd exploits cross correlation of diffraction patterns to measure intragranular misorientations with precision on the order of 0 01 with well constrained misorientation axes we investigate the dislocation structures of chessboard subgrains in quartz within samples from the greater himalayan sequence nepal our results demonstrate that chessboard subgrains are formed primarily from two sets of subgrain boundaries one set consists primarily of m c edge dislocations the other consists primarily of dislocations with a burgers vectors apparent densities of geometrically necessary dislocations vary from 10 13 m 2 within some subgrain boundaries to 12 m 2 within subgrain interiors the results suggest that at pressures above approximately 10 kbar chessboard subgrains may form within the quartz stability field most importantly this study demonstrates the potential of hr ebsd as an improved method for analysis of intragranular microstructures in quartz that are used as indicators of deformation conditions

automatic classification of dome instabilities based on doppler radar measurements at merapi volcano indonesia part i summary in this paper we analyse a 3 yr long time series of activity at merapi volcano indonesia which was recorded using a doppler radar system between november 2001 and july 2004 about 57 000 events associated with dome instabilities have been recorded by the radar system because of the huge amount of data an automatic classification system has been developed which identifies different types of instabilities at the lava dome i e sliding material gravitational break offs and explosive outbursts as well as rainfall comparing the record of detected instabilities to rockfall measurements deduced from the seismic network of the volcanological technology research center vtrc we are able to demonstrate the high potential of doppler radar measurements for monitoring of dome activity when aligned to the most active area at the dome the radar detects significantly more events than the seismic system in combination with seismic measurements the doppler radar allows for identifying changes in the location of the most active area at the dome this is particularly helpful since the dome of merapi is covered by clouds about 50 per cent of the time additionally the radar data can help to distinguish between rockfalls and multiphase events in the seismic measurements the different types of instabilities have been analysed for their occurrence frequency in terms of size volume and mean velocity significant temporal changes in the relative occurrence frequencies or the characteristic properties of the different types of instabilities have not been observed however during the period of fastest activity decrease explosive instability events with a gravitational precursor decreased faster than events starting explosively because the radar system is able to observe rainfall the data has been analysed for a link between rain and dome activity throughout the observation period no such link could be found however this might be due to the fact that the activity has been almost continuously decreasing

textures and c axis orientations of deformed quartz crystals from porphyric dikes of the alpine root zone western alps deformation textures and c axis preferred orientations of quartz phenocrysts from porphyric dikes of the alpine root zone have been formed under conditions of greenschist to low amphibolite facies it is shown that the deformation textures as shear planes and kink bands boudins grain boundary sutures subgrains coarse and fine recrystallized grains deformation lamellae and fractures are developed in a chronological sequence during first increasing and later decreasing temperatures

unusual transition in quartzite dislocation creep regimes and crystal slip systems in the aureole of the eureka valley joshua flat beer creek pluton california a case for anhydrous conditions created by decarbonation reactions abstract microstructures and quartz c axis fabrics were analyzed in five quartzite samples collected across the eastern aureole of the eureka valley joshua flat beer creek composite pluton temperatures of deformation are estimated to be 740 50 c based on a modified c axis opening angle thermometer of kruhl j metamorph geol 16 1998 142 in quartzite layers located closest 140 m to the pluton wall rock contact flattened detrital grains are plastically deformed and partially recrystallized the dominant recrystallization process is subgrain rotation dislocation creep regime 2 of hirth and tullis j struct geol 14 1992 145 although grain boundary migration dislocation creep regime 3 is also evident complete recrystallization occurs in quartzite layers located at a distance of 240 m from the contact and coincides with recrystallization taking place dominantly through grain boundary migration regime 3 within the quartzites strain is calculated to be lowest in the layers closest to the pluton margin based on the aspect ratios of flattened detrital grains the c axis fabrics indicate that a slip operated within the quartzites closest to the pluton wall rock contact and that with distance from the contact the operative slip systems gradually switch to prism c slip the spatial inversion in microstructures and slip systems apparent high temperature deformation and recrystallization further from the pluton contact and apparent low temperature deformation and recrystallization closer to the pluton contact coincides with a change in minor phase mineral content of quartzite samples and also in composition of the surrounding rock units marble and calc silicate assemblages dominate close to the pluton wall rock contact whereas mixed quartzite and pelite assemblages are dominant further from the contact we suggest that a thick marble unit located between the pluton and the quartzite layers acted as a barrier to fluids emanating from the pluton decarbonation reactions in marble layers interbedded with the inner aureole quartzites and calc silicate assemblages in the inner aureole quartzites may have produced high x co 2 water absent fluids during deformation the presence of high x co 2 fluid is inferred from the prograde assemblage of quartz calcite and not wollastonite diopside k feldspar in the inner aureole quartzites we suggest that it was these dry conditions that suppressed prism c slip and regime 3 recrystallization in the inner aureole and resulted in a slip and regime 2 recrystallization which would normally be associated with lower deformation temperatures in contrast the prograde assemblage in the pelite dominated outer part of the aureole is biotite k feldspar these wet pelitic assemblages indicate fluids dominated by water in the outer part of the aureole and promoted prism c slip and regime 3 recrystallization because other variables could also have caused the spatial inversion of c axis fabrics and recrystallization mechanisms we briefly review those variables known to cause a transition in slip systems and dislocation creep regimes in quartz our conclusions are based on a small number of samples and therefore the unusual development of crystal fabrics and microstructures in the aureole to the ejb pluton suggests that further study is needed on the effect of fluid composition on crystal slip system activity and recrystallization mechanisms in naturally deformed rocks

a quantitative assessment of the genetic sources of the hydrologic flow regimes in upper indus basin and its significance in a changing climate summary reliable quantitative estimates of contributions melt water of different genetic sources make to river flows in himalayan river basins are largely unknown here we provide such estimates for upper indus basin uib analyses of historical flow records at 11 gauging stations spanning 14 48 years during a period of record from 1962 to 2010 reveal a uniform character of annual flow distributions at all gauging stations given by a gaussian function implying a unique glacio hydrometeorological condition prevailing throughout the basin controlling four hydrologic flow regimes within uib two low flow regimes occur during the months of october to december l1 and january to march l2 and two high flow regimes that occur during april june h1 and july september h2 for all stations flow magnitudes follow h2 h1 l1 l2 in the main stem of upper indus river the contributions to total annual flow volumes m 3 during these flow regimes are 53 62 during h2 24 32 during h1 8 9 during l1 and 4 6 during l2 in the main tributaries these ranges are 47 74 during h2 15 38 during h1 8 10 during l1 and 4 6 during l2 separation of annual hydrographs by linear smoothing and recursive digital filtering technique shows that the annual contribution of melt water m2 from an elevation band 3500 5300 m to total annual flow volume m 3 varies from 41 to 54 along the main stem of indus upstream of the himalayan foothills contribution of melt water m1 from an elevation band 2500 3500 m varies from 16 to 29 in the tributaries annual contributions of m2 vary from 37 to as high as 65 similarly annual contributions of m1 in the tributaries vary from as low as 12 to 34 thus the relative importance of melt water originating from high altitudes far overweighs that originating from mid altitudes in river runoff within uib the chief component of m1 is seasonal snows whereas m2 is a mixture of glacial melts seasonal snows falling in winter and spring and monsoonal snows falling in the summer july september the m2 component contributes to base flows during l1 regime base flow recession occurs during l2 regime during the h2 regime three watersheds with greatest glaciated surfaces straddling the karakoram mountains contribute 48 54 of flows at shatial bridge a point upstream of tarbela reservoir up to which rainfall contributions to river discharges in uib are inconsequential during the h1 regime these watersheds drained by shyok shigar and hunza rivers contribute 20 31 of flows at this point during l1 and l2 regimes their contributions are 33 39 and 31 32 respectively contributions of glacial melt and snowmelt to annual river flows vary from 18 35 and 38 50 respectively in the major tributaries and the main stem of upper indus depending on the location upper indus river just upstream of tarbela reservoir carries annual flows constituted of 70 melt water of which 21 is contributed by glacial melts and 49 by snowmelts thus changes in climatic trends will greatly control the future water availability within uib if glacial retreat and reduction of the perennial snow and ice covers are happening in uib in a changing climate then there will indeed be long term reductions in river flows in uib and hence sustainability of water resources in this basin will potentially be at risk

using thermal remanent magnetisation trm to distinguish block and ash flow and debris flow deposits and to estimate their emplacement temperature 1991 1995 lava dome eruption at mt unzen volcano japan abstract the 1991 1995 mt unzen eruption kyushu japan produced 13 lava domes approximately 9400 block and ash pyroclastic flows baf resulting from lava dome collapse events and syn and post dome collapse debris flow df events in the field it can be very difficult to distinguish from field facies characteristics which deposits are primary hot baf cold baf or rock avalanche or secondary df deposits in this study we use a combination of field observations and thermal remanent magnetisation trm analysis of juvenile lava dome derived clasts from seven deposits of the 1991 1995 mt unzen eruption in order to distinguish between primary baf deposits and secondary df deposits and to determine their emplacement temperature four major trm patterns were identified 1 type i clasts with a single magnetic component oriented parallel to the earth s magnetic field at time and site of emplacement this indicates that these deposits were deposited at very high temperature between the curie temperature of magnetite 540 c and the glass transition temperature of the lava dome 745 c these clasts are found in high temperature baf deposits 2 type ii clasts with two magnetic components of magnetisation the lower temperature magnetic components are parallel to the earth s magnetic field at time of the unzen eruption temperature estimations for these deposits can range from 80 to 540 c we found this paleomagnetic behaviour in moderate temperature baf or warm df deposits 3 type iii clasts with three magnetic components with a lower temperature component oriented parallel to the earth s magnetic field at unzen the individual clast temperatures estimated for this kind of deposit are usually less than 300 c we interpret this paleomagnetic behaviour as the effect of different thermal events during their emplacement history there are several interpretations for this paleomagnetic behaviour including remobilisation of moderate temperature baf warm df or syn eruptive granular flows 4 type iv clasts with single or two magnetic components that are randomly oriented suggesting an emplacement at ambient temperature these clasts are found in df and syn eruptive rock avalanche deposits containing high proportion of well rounded clasts and non carbonised vegetation we demonstrate that trm analysis associated with field observations can be a viable method for determining the emplacement temperature of hot baf and cold df deposits characterised by similar componentry and sedimentological facies this has implications for hazard assessment of older dormant volcanic systems to reconstruct the eruptive history

regional earthquake as a trigger for enhanced volcanic activity evidence from modis thermal data 1 the magnitude 6 4 earthquake that occurred in java on 26 may 2006 provided us with data capable of revealing an immediate eruptive response at two javanese volcanoes merapi and semeru the availability of pre processed thermal data for volcanic hot spots detected by the moderate resolution imaging spectrometer modis and provided on http hotspot higp hawaii edu allowed us to produce heat and volume flux time series for these two erupting volcanoes covering a 35 day period spanning the earthquake our results revealed a coupled response by the volcanoes to the earthquake both experiencing increases in heat and volume flux beginning 3 days after the earthquake with the response lasting 9 days the response was felt at both volcanoes as a factor of two to three increase in the rate of volumetric output after which output returned to the pre response rates this implies that the earthquake triggered enhanced output at two erupting volcanoes 50 and 300 km distant from the earthquake epicenter and separated from each other by 260 km

quartz textures from the simplon fault zone southwest switzerland and north italy quartz textures measured from monomineralic veins within the simplon fault zone show very similar patterns over a strike length of some 30 km the c axes form asymmetric kinked single girdles with variably developed vestiges of crossed girdle limbs the kinking of the girdle may be controlled by the two c axis orientations where double rhomb a slip is possible a strong a maximum lies between 20 and 30 to the lineation in the xz plane which seems too large to be the angle to the bulk shear plane straight single girdle patterns may be possible for strict simple shear in natural fault zones where deformation is in general heterogeneous on all scales kinked single girdles and type i crossed girdle textures are much more common perhaps because such textures provide more freedom to accommodate a general two dimensional strain

ice velocity and climate variations for baltoro glacier pakistan quincey dj copland l mayer c bishop m luckman a belo m 2009 ice velocity and climate variations for the baltoro glacier pakistan journal of glaciology 55 194 1061 1071 sponsorship rcuk us national science foundation us national geographic society natural sciences and engineering research council of canada canadian foundation for innovation ontario research fund university of ottawa

tributary glacier surges an exceptional concentration at panmah glacier karakoram himalaya four tributaries of panmah glacier have surged in less than a decade three in quick succession between 2001 and 2005 since 1985 13 surges have been recorded in the karakoram himalaya more than in any comparable period since the 1850s ten were tributary surges in these ten a full run out of surge ice is prevented but extended post surge episodes affect the tributary and main glacier the sudden concentration of events at panmah glacier is without precedent and at odds with known surge intervals for the glaciers interpretations must consider the response of thermally complex glaciers at exceptionally high altitudes and of high relief to changes in a distinctive regional climate it is suggested that high altitude warming affecting snow and glacier thermal regimes or bringing intense short term melting episodes may be more significant than mass balance change

signature and hydrologic consequences of climate change within the upper middle brahmaputra basin a prevailing perception is that the glaciers and perennial snow and ice covered areas scap or in the himalayan region are fast contracting however systematic studies providing the quantitative estimates of scap as a function of time within individual river basins are lacking the importance of meltwater in river flows varies greatly from one river basin to another yet the actual estimates of those contributions are largely unknown this study bridges such knowledge gaps for the upper middle brahmaputra basin by using best available digital cartographic and remotely sensed snow cover data we find that when the entire basin is considered scap decreased from 7637 764 in 1980 to 4298 1422 km2 in 1992 however it has increased to 7160 2248 km2 in 2000 from 2000 to 2010 the scap has remained nearly constant around a mean of 10 052 1468 km2 the same trend is observed within individual physiographic zones of the basin such increase in scap is due to the increase in the precipitation over the middle brahmaputra basin and the nyainquentanglha mountains as observed in station records the incursion of moist air through the brahmaputra valley to the higher elevations within the nyainquentanglha mountains causes snowfall during pre monsoonal and post monsoonal seasons and an expansion of the scap glacial expansions in the nyainquentanglha mountains have also been observed in other recent studies in addition to the increase in precipitation and scap another manifestation of climate change observed in this basin is the increasing temperature with a mean annual trend of 0 28 c decade the hydrologic consequences of the observed effects of climate change are expected to be an insignificant change in streamflows in the watersheds drained by the upper brahmaputra river but a perceptible increase in river discharges in the watersheds drained by the middle brahmaputra river and its tributaries particularly within the upper and lower catchments of the middle brahmaputra basin copyright 2012 john wiley sons ltd

evidence for welding of a block and ash pyroclastic flow deposit the case of cerro bravo volcano colombia cerro bravo is an active composite volcano located in the san diego cerro machin volcano tectonic province scvtp the northernmost volcanic chain in the colombian andes among the products associated with the volcano there is a peculiar indurated deposit emplaced between 7 and 2 9 ka which resembles a block and ash pyroclastic flow deposit through field observations physical property analyses petrography and scanning electron microscopy sem we demonstrate that this induration is the result of welding processes high density deformed glassy fragments with a common orientation low porosity fiamme and sintering are the most visible characteristics the evidence indicates that welding reached up to rank iv in a i to vi classification scheme we suggest that welding is associated with 1 high emplacement temperature related to the syneruptive destruction of a growing endogenous dome and 2 a low glass transition temperature related to the influence of upward water diffusion after emplacement of the flow over wet ground thus with emplacement temperatures between 670 and 540 c and water contents between 0 5 and 1 2 wt the welding process was unusually efficient calculations made indicate that for the deposit to present the observed characteristics of welding the emplacement temperature needed to exceed the threshold of the glass transition temperature for a time of 5 6 days and have an effective viscosity of 1012 pa s as a result of the welding the deposit decreased its thickness by between 15 and 7 m this work contributes to the knowledge of welding processes and stresses the unusual occurrence of welding in this type of pyroclastic flow deposit which thus requires special emplacement conditions in terms of temperature and water content

macro and microstructural analysis of the zhujiafang ductile shear zone hengshan complex tectonic nature and geodynamic implications of the evolution of trans north china orogen