the glueckstadt graben of the north german basin new insights into the structure from 3d and 2d gravity analyses the structure of the glueckstadt graben has been investigated by use of 3d gravity backstripping technique and by 2d gravity and magnetic modelling subtracting the gravity effects of the meso cenozoic sediments together with permian salt reveals a positive residual anomaly within the glueckstadt graben this anomaly includes two local maxima over the westholstein and eastholstein troughs the 2d gravity models point to the presence of a high density body within the lower crust of the glueckstadt graben in addition the results of 2d magnetic modelling indicate that the central part of the high density body is overlain by an area with high susceptibility most probable the formation of this high density body is a result of complex poly phase tectonic history of the study area finally the results of gravity modelling indicate that permian salt is not homogeneous 3d gravity analysis and especially 2d gravity modelling have distinguished the differences in degree of salt saturation in salt rich bodies and elucidate the proportion of rotliegend salt

an elastic plate model for interseismic deformation in subduction zones geodetic observations of interseismic surface deformation in the vicinity of subduction zones are frequently interpreted using simple kinematic elastic dislocation models edm in this theoretical study we develop a kinematic edm that simulates plate subduction over the interseismic period the elastic subducting plate model espm having only 2 more degrees of freedom than the well established back slip model bsm an elastic plate thickness and the fraction of flexural stresses due to bending at the trench that are released continuously unlike the bsm in which steady state deformation in both plates is assumed to be negligible the espm includes deformation in the subducting and overriding plates owing to plate thickness while still preserving the correct sense of convergence velocity between the subducting and overriding plates as well as zero net steady state vertical offset between the two plates when integrated over many seismic cycles the espm links elastic plate flexure processes to interseismic deformation and helps clarify under what conditions the bsm is appropriate for fitting interseismic geodetic data at convergent margins we show that the espm is identical to the bsm in the limiting case of zero plate thickness thereby providing an alternative motivation for the bsm the espm also provides a consistent convention for applying the bsm to any megathrust interface geometry even in the case of nonnegligible plate thickness the deformation field predicted by the espm reduces to that of the bsm if stresses related to plate flexure at the trench are released either continuously and completely at shallow depths during the interseismic period or deep in the subduction zone below 100 km however if at least a portion of these stresses are not continuously released in the shallow portion of the subduction zone via seismic or aseismic events then the predicted surface velocities of these two models can differ significantly at horizontal distances from the trench equivalent to a few times the effective interseismic locking depth

miocene jiali faulting and its implications for tibetan tectonic evolution the karakoram jiali fault zone kjfz comprises a series of right lateral shear zones that southerly bound the eastward extrusion of northern tibet relative to india and stable eurasia here we present new 40 ar 39 ar age data from the puqu and parlung faults two easternmost branches of the jiali fault zone which indicate a main phase of the kjfz shearing from v18 to 12 ma thus the tibetan eastward extrusion bounded by principal strike slip fault zones started and was probably most active around the middle miocene an interval marked also by active east west extension in southern tibet the coincidence of these two tectonic events strongly suggests a common causal mechanism which is best explained as oblique convergence between india and asia under the framework of this mechanism the extension in southern tibet is not a proxy for the plateau uplift the kjfz activity was furthermore coincident with right lateral displacements along the gaoligong and sagaing faults in southeast asia this defines a miocene deformation record for the regional dextral accommodation zone that in response to the continuing india asia collision may have accounted for the initiation and prolonged history of clockwise rotation of the tibetan extrusion around the eastern himalayan syntaxis 2002 elsevier science b v all rights reserved

long term stability of flow path structure in crystalline rocks distributed in an orogenic belt japan most evaluations of the contaminant retardation processes likely to be important in geological disposal e g for high level radioactive waste hlw consider only the present characteristics of fractures and associated mineral infills relatively little attention has been given to possible long term changes in these features and their influence on groundwater flow the work reported here seeks to provide analogous evidence that such changes are not likely to be important and hence to improve confidence in the presently adopted evaluation methodology and its long term applicability in the orogenic belt that is formed by the japanese islands there are wide areas of crystalline rock the rocks in each area have a distinctive age sequence which is partly reflected in the characteristics of the fracture systems and associated mineral fillings that occur these characteristics generally imply that groundwater and solutes can be conducted through fracture networks except in the cases of fault zones or crushed zones the structural and mineralogical features of these networks readily illustrate how certain contaminants might react and be retarded by the fracture fillings and open pore geometry due to chemical sorption and or physical retardation here we describe the fracture systems developed in crystalline rocks with different ages that are intruded into the japanese orogenic belt the aim is to build a model for the long term fracturing process and hence to evaluate fracture dstabilityt i n particular the comparisons are made between the fracture geometries and the frequencies observed in the 1 9 0 8 ma takidani granodiorite the youngest exposed pluton in the world the ca 67 ma toki granite and the ca 117 ma kurihashi granodiorite located in central to northwest japan the observations show that all these crystalline rocks have similar fracture frequencies with 1 to 2 fractures per meter in the massive part of rock bodies mineralogical studies and dating analyses of fracture fillings also suggest that fractures are relatively physically stable major new fractures tend not to be created in the massive part of rock bodies even when a pluton has been subjected to the regional stresses of plate movements with a duration of about 100 ma the results show the unique characteristics of the fracture forming process and the relatively stable geometries of fracture network systems in crystalline rocks distributed within the orogenic belt this analogue also enables us to provide a model to build confidence in a technical approach applicable for modeling of hydrogeology and geology over long time scales under the

indian punch rifts tibet the strikes of late cenozoic normal faults in tibet fan systematically from a northwesterly to northeasterly direction from west to east they exhibit an axis of symmetry that bisects the himalayan arc and trends subparallel to india asia motion the two dimensional stress field inferred from the spatial pattern of normal fault orientations can be explained solely by collisional stresses localized along a southern part of the himalayan arc continued insertion of indian crust into tibet can explain the persistence of extension and may be increasing plateau crustal thickness and elevation coeval with rifting

convergence rate across the nepal himalaya and interseismic coupling on the main himalayan thrust implications for seismic hazard we document geodetic strain across the nepal himalaya using gps times series from 30 stations in nepal and southern tibet in addition to previously published campaign gps points and leveling data and determine the pattern of interseismic coupling on the main himalayan thrust fault mht the noise on the daily gps positions is modeled as a combination of white and colored noise in order to infer secular velocities at the stations with consistent uncertainties we then locate the pole of rotation of the indian plate in the itrf 2005 reference frame at longitude 1 34 3 31 latitude 51 4 0 3 with an angular velocity of 0 5029 0 0072 myr the pattern of coupling on the mht is computed on a fault dipping 10 to the north and whose strike roughly follows the arcuate shape of the himalaya the model indicates that the mht is locked from the surface to a distance of approximately 100 km down dip corresponding to a depth of 15 to 20 km in map view the transition zone between the locked portion of the mht and the portion which is creeping at the long term slip rate seems to be at the most a few tens of kilometers wide and coincides with the belt of midcrustal microseismicity underneath the himalaya according to a previous study based on thermokinematic modeling of thermochronological and thermobarometric data this transition seems to happen in a zone where the temperature reaches 350 c the convergence between india and south tibet proceeds at a rate of 17 8 0 5 mm yr in central and eastern nepal and 20 5 1 mm yr in western nepal the moment deficit due to locking of the mht in the interseismic period accrues at a rate of 6 6 0 4 10 19 nm yr on the mht underneath nepal for comparison the moment released by the seismicity over the past 500 years including 14 m w 7 earthquakes with moment magnitudes up to 8 5 amounts to only 0 9 10 19 nm yr indicating a large deficit of seismic slip over that period or very infrequent large slow slip events no large slow slip event has been observed however over the 20 years covered by geodetic measurements in the nepal himalaya we discuss the magnitude and return period of m 8 earthquakes required to balance the long term slip budget on the mht

mantle dynamics uplift of the tibetan plateau and the indian monsoon convective removal of lower lithosphere beneath the tibetan plateau can account for a rapid increase in the mean elevation of the tibetan plateau of 1000 m or more in a few million years such uplift seems to be required by abrupt tectonic and environmental changes in asia and the indian ocean in late cenozoic time the composition of basaltic volcanism in northern tibet which apparently began at about 13 ma implies melting of lithosphere not asthenosphere the most plausible mechanism for rapid heat transfer to the midlithosphere is by convective removal of deeper lithosphere and its replacement by hotter asthenosphere the initiation of normal faulting in tibet at about 8 3 ma suggests that the plateau underwent an appreciable increase in elevation at that time an increase due solely to the isostatic response to crustal thickening caused by india s penetration into eurasia should have been slow and could not have triggered normal faulting another process such as removal of relatively cold dense lower lithosphere must have caused a supplemental uplift of the surface folding and faulting of the indo australian plate south of india the most prominent oceanic intraplate deformation on earth began between about 7 5 and 8 ma and indicates an increased north south compressional stress within the indo australian plate a tibetan uplift of only 1000 m if the result of removal of lower lithosphere should have increased the compressional stress that the plateau applies to india and that resists india s northward movement from an amount too small to fold oceanic lithosphere to one sufficient to do so the climate of the equatorial indian ocean and southern asia changed at about 6 9 ma monsoonal winds apparently strengthened northern pakistan became more arid but weathering of rock in the eastern himalaya apparently increased because of its high altitude and lateral extent the tibetan plateau provides a heat source at midlatitudes that should oppose classical symmetric hadley circulation between the equator and temperate latitudes and that should help to drive an essentially opposite circulation characteristic of summer monsoons for the simple case of axisymmetric heating no dependence on longitude of an atmosphere without dissipation theoretical analyses by hou lindzen and plumb show that an axisymmetric heat source displaced from the equator can drive a much stronger meridianal monsoonlike circulation than such a source centered on the equator but only if heating exceeds a threshold whose level increases with the latitude of the heat source because heating of the atmosphere over tibet should increase monotonically with elevation of the plateau a modest uplift 1000 2500 m of tibet already of substantial extent and height might have been sufficient to exceed a threshold necessary for a strong monsoon the virtual simultaneity of these phenomena suggests that uplift was rapid approximately 1000 m to 2500 m in a few million years moreover nearly simultaneously with the late miocene strengthening of the monsoon the calcite compensation depth in the oceans dropped plants using the relatively efficient c4 pathway for photosynthesis evolved rapidly and atmospheric co2 seems to have decreased suggesting causal relationships and positive feedbacks among these phenomena both a supplemental uplift of the himalaya the southern edge of tibet and a strengthened monsoon may have accelerated erosion and weathering of silicate rock in the himalaya that in turn enhanced extraction of co2 from the atmosphere thus these correlations offer some support for links between plateau uplift a downdrawing of co2 from the atmosphere and global climate change as proposed by raymo ruddiman and froehlich mantle dynamics beneath mountain belts not only may profoundly affect tectonic processes near and far from the belts but might also play an important role in altering regional and global climates

evolution of the lower saxony basin abstract the lower saxony basin is a 300 km long and 65 km wide late jurassic and early cretaceous trough which parallels the northern margin of the rhenish massif this basin became inverted during the senonian and paleocene the lower saxony basin is the most important oil province of germany past production amounts to 200 10 6 t of oil 1 5 10 9 bbl the lower saxony basin is superimposed on the late carboniferous variscan foredeep basin and the frontal structures of the variscan fold belt during the permian to middle jurassic the area formed part of the northwest european basin differential subsidence of the lower saxony basin was initiated during the late jurassic and persisted till albian time this involved reactivation of permo carboniferous fracture systems by divergent wrenching a major aptian deep seated laccolith is evident in the western part of the lower saxony basin during the senonian and paleocene sinistral convergent wrenching induced uplift of the basin floor and folding of its sedimentary fill the margins of the inverted lower saxony basin are thrust over the adjacent stable platform areas the differential subsidence of the lower saxony basin can be related to a period of major crustal extension in the north sea rift basin inversion coincides with important orogenic events in the alpine system and is thought to have been induced by intra plate compressional stresses

mid crustal ramping of the main himalayan thrust in nepal to bhutan himalaya new insights from analogue and numerical experiments abstract the mid crustal ramp on the main himalayan thrust mht in the lesser himalaya sequence lhs is the most critical geometrical asperity to trigger major seismic events in the himalaya including the 2015 mw 7 8 gorkha nepal earthquake however it is still not well understood what caused the mht to ramp up at laterally varying locations in central to eastern himalaya during the southward propagation of the himalayan tectonic wedge based on laboratory and numerical model experiments approximated to the central nepal and eastern bhutan himalayan geological settings we show that the coal bearing gondwana horizon in the stratigraphic sequence has played a crucial role in producing the mid crustal ramp on the mht during the southward propagation of the himalayan wedge the mechanically weak gondwana sequence resulted in strain localization at its northern edge and it eventually caused the mht to ramp from a depth of 20 km to 6 7 km combining our experimental and field observations with the geophysical sections we interpret that a strike wise non uniform occurrence of the gondwana horizon is responsible for the mht to ramp at different locations separated by n s trending natural barriers like tear faults the weak zone model also explains the rock uplift versus erosion pattern recorded in central nepal the ramp induced surface uplift rates calculated from our model are in good agreement with those reported from central nepal u 0 28 normalized to the convergent rate

segmentation of the main himalayan thrust illuminated by bayesian inference of interseismic coupling we use a recent compilation of geodetic data of surface displacements in a fully bayesian approach to derive a probabilistic estimate of interseismic coupling along the main himalayan thrust mht our probabilistic estimate of interseismic coupling highlights four large highly coupled patches separated by three potential barriers of low coupling locked patches overlap with estimated rupture areas of historical large earthquakes over the past centuries the coincident spatial variability in coupling seismicity and prominent active topography suggests a structural segmentation of the mht imposed by inherited tectonic structures from the india eurasia collision this correlation implies that inherited tectonic structures may affect how stress builds up along the mht thereby influencing the location and size of large himalayan earthquakes and the growth of the mountain range

the age and rate of displacement along the main central thrust in the western bhutan himalaya abstract in western bhutan the main central thrust mct is broadly folded creating multiple exposures of the fault surface over a 70 km across strike distance this unusual map pattern presents a unique opportunity to map the mct and document both the magnitude and age of displacement in situ th pb sims and la icp ms geochronology of metamorphic monazite from the immediate hanging wall of the mct indicates that prograde monazite growth in greater himalayan gh rocks continued until 20 8 1 1 ma whereas crystallization of in situ melts characterized by high y monazite overgrowths occurred during cooling from ca 15 10 ma prograde monazite growth at 15 ma in lesser himalaya lh rocks in the immediate footwall requires that lh footwall strata began to be buried at this time and the mct had reached its southernmost exposed extent by combining prograde monazite ages in the immediate hanging wall and footwall the duration of mct displacement is bracketed between 20 8 1 1 and 15 0 2 4 ma immediately north of our study area a published estimate of shearing along the outer south tibetan detachment std argues for displacement between 20 and 15 ma coeval with the age range for mct displacement that we document in this study however retrograde monazite grains as young as 10 ma suggest that gh rocks were cooling until 10 ma 5 myr later than motion on the outer std immediately to the north this cooling was either the result of continued displacement on the mct or growth of a duplex that passively folded the mct using a sequential reconstruction we estimate a total displacement of 230 km which is the sum of displacements on the mct and the structurally lower paro thrust over a duration of 5 8 2 6 myr this indicates a horizontal shortening rate of 4 0 3 2 1 3 cm yr which exceeds present rates estimated from geodetic measurements across the himalaya and mct displacement rates c 2 cm yr inferred from petrologic and thermal models in central nepal but is indistinguishable from plate convergence rates calculated for eastern bhutan between 23 and 20 ma 3 3 0 7 cm yr our study highlights that displacement on the mct alone achieved plate velocity rates in western bhutan and that the age and rate of mct displacement varied significantly across the himalaya

geodetic imaging mega thrust coupling beneath the himalaya abstract the 2015 gorkha earthquake highlights the urgent need for understanding seismicity in the himalaya which is envisaged to be governed by stick slip behavior on the main himalayan thrust mht beneath the southern edge of the tibetan plateau we integrate gps data in southern tibet with those public available for geodetic imaging of the frictional properties of the seismogenic fault aiming at a better understanding of the strain buildup on the largest continental mega thrust and its relation to great earthquakes the postseismic effects due to viscoelastic relaxation from three large earthquakes 1934 bihar mw 8 4 1950 assam mw 8 5 and 2005 kashmir mw 7 6 are corrected in the coupling modeling the new model constrained by all gps velocities spirit leveling rates and insar interferograms spread between the eastern and western himalayan syntaxes confirms previous findings that the mht is fully locked in the uppermost 15 20 km of crust below which an abrupt decrease in coupling occurs with coefficients reduced from 0 8 to 0 2 within a narrow transition zone of 30 50 km in width generally the coupling pattern is modified little after removing the postseismic contributions of the 1934 bihar and 2005 kashmir earthquakes from gps velocities meanwhile the high coupling region around the eastern himalayan syntaxis is widened from 100 km to 140 km after removing the perturbation induced by the 1950 assam earthquake the spatial variation of fault coupling coincides well with the epicentral areas of historical earthquakes in the sikkim and bhutan himalaya the locking zone is wider than elsewhere along the himalaya the strain buildup for the past 300 years under the bhutan himalaya would be sufficient to power a maximum earthquake of mw 8 6

three dimensional velocity field of present day crustal motion of the tibetan plateau derived from gps measurements 1 using the measurements of 750 gps stations around the tibetan plateau for over 10 years since 1999 we derived a high resolution 3 d velocity field for the present day crustal movement of the plateau the horizontal velocity field relative to stable eurasia displays in details the crustal movement and tectonic deformation features of the india eurasia continental collision zone with thrust compression lateral extrusion and clockwise rotation the vertical velocity field reveals that the tibetan plateau is continuing to rise as a whole relative to its stable north neighbor however in some subregions uplift is insignificant or even negative the main features of the vertical crustal deformation of the plateau are the following a the himalayan range is still rising at a rate of 2 mm yr the uplift rate is 6 mm yr with respect to the south foot of the himalayan range b the middle eastern plateau has a typical uplift rate between 1 and 2 mm yr and some high mountain ranges in this area like the longmen shan and gongga shan have surprising uplift rates as large as 2 3mm yr c in the middle southern plateau there is a basin and endorheic subregion with a series of ns striking normal faults showing obvious sinking with the rates between 0 and 3 mm yr d the present day rising and sinking subregions generally correspond well to the cenozoic orogenic belts and basins respectively e at the southeastern corner of the plateau there is an apparent trend that the uplift rate is gradually decreasing from between 0 8 and 2 3 mm yr in the inner plateau to between 0 5 and 1 6 mm yr outside the plateau with the decrease of terrain height

present day crustal motion within the tibetan plateau inferred from gps measurements 1 using the measurements of 726 gps stations around the tibetan plateau we determine the rigid rotation of the entire plateau in a eurasia fixed reference frame which can be best described by an euler vector of 24 38 0 42 n 102 37 0 42 e 0 7096 0 0206 ma the rigid rotational component accommodates at least 50 of the northeastward thrust from india and dominates the eastward extrusion of the northern plateau after removing the rigid rotation to highlight the interior deformation within the plateau we find that the most remarkable interior deformation of the plateau is a glacier like flow zone which starts at somewhere between the middle and western plateau goes clockwise around the eastern himalayan syntaxis ehs and ends at the southeast corner of the plateau with a fan like front the deformation feature of the southern plateau especially the emergence of the flow zone could be attributed to an eastward escape of highly plastic upper crustal material driven by a lower crust viscous channel flow generated by lateral compression and gravitational buoyancy at the later developmental stage of the plateau the first order feature of crustal deformation of the northeastern plateau can be well explained by a three dimensional elastic half space dislocation model with rates of dislocation segments comparable to the ones from geological observations in the eastern plateau although gps data show no significant convergence between the eastern margin of the plateau and the sichuan basin a small but significant compressional strain rate component of 10 5 2 8 nstrain yr exists in a relatively narrow region around the eastern margin in addition a large part of the eastern plateau northeast of the ehs is not undergoing shortening along the northeastward convergence direction of the ehs but is stretching

lithospheric pressure depth relationship in compressive regions of thickened crust we investigate the pressure distribution with depth in regions undergoing horizontal shortening and experiencing crustal thickening both analytically and numerically our results show that in a convergent tectonic setting pressure can be considerably higher than lithostatic the pressure resulting from the weight of the overburden increases in pressure with respect to lithostatic conditions result from both the contribution of horizontal stresses and the flexural vertical loads the latter generated by the deflection of the upper crust and of the mantle because of the presence of topographic relief and a root respectively the contribution of horizontal stresses is particularly relevant to the upper crust and uppermost mantle where rocks are thought to deform brittlely in these domains pressure gradients twice lithostatic can be achieved the contribution of horizontal stresses is less important in the ductile domains as diverential stresses are progressively relaxed nevertheless the evects are still noteworthy especially close to the brittle ductile transition flexural vertical loads generated by the deflection of the upper crust and lithospheric mantle are relevant for rocks of the weaker lower crust as a result of the combination of the two mechanisms the pressure gradient varies vertically through the lithosphere ranging from negative inverted gradients to gradients up to several times the lithostatic gradient the pressure values range from one to two times the lithostatic values 1rgz to 2rgz

impact of near surface fault geometry on secular slip rate assessment derived from uplifted river terraces implications for convergence accommodation across the frontal thrust in southern central bhutan vertical velocities obtained from uplifted river terrace dating near mountain fronts are commonly converted into overthrusting slip rates assuming simple geometry of the fault at depth however the lack of information on the dip angle of these shallow structures can lead to misinterpretation in the accommodation of convergence and thus to erroneous conclusions on the transfer of shortening to the emergent thrust faults here to assess the impact of fault geometry we focus on the eastern himalayan region in the south central bhutan where the topographic frontal thrust tft has been already documented by gps paleoseismic geomorphic and geological studies this study is based on high resolution near surface geophysical investigations including electrical resistivity seismic and gravity measurements using a similar stochastic inversion approach for all data sets new quantitative constraints on both fault geometry and petrophysical parameters are obtained to image shallow depths in the upper ca 80 m the combined results from both surface observations and geophysical measurement provide a tft geometry that is dipping northwards with a shallow angle at the top 0 5 m steeply dipping in the middle 5 40 m and flattening at deeper depths 40 m together our new constraints on the fault geometry allow us to estimate a minimum overthrusting slip rate of 10 2 mm yr 1 which is only a part of the ca 17 mm yr 1 gps convergence this suggests that in the study area significant deformation partitioning on several faults including tft and the main boundary thrust cannot be ruled out more importantly assuming constant slip rate the obtained dip angle variations lead to uplift rate changes with distance to the tft this underlines that taking into account uplift rate from terrace dating only at the front location and assuming a constant dip angle fault geometry based on surface observations may significantly bias the slip rate estimates

structure and evolution of the glueckstadt graben due to salt movements the salt tectonics of the glueckstadt graben has been investigated in relation to major tectonic events within the basin the lithologic features of salt sections from rotliegend zechstein and keuper show that almost pure salt is prominent in the zechstein dominating diapiric movements that have influenced the regional evolution of the glueckstadt graben three main phases of growth of the salt structures have been identified from the analysis of the seismic pattern the strongest salt movements occurred at the beginning of the keuper when the area was affected by extension this activation of salt tectonics was followed by a jurassic extensional event in the pompeckj block and lower saxony basin and possibly in the glueckstadt graben the paleogene neogene tectonic event caused significant growth and amplification of the salt structures mainly at the margins of the basin this event was extensional with a possible horizontal component of the tectonic movements 3d modelling shows that the distribution of the initial thickness of the permian salt controls the structural style of the basin regionally where salt was thick salt diapirs and walls formed and where salt was relatively thin simple salt pillows and shallow anticlines developed

clockwise rotation of the brahmaputra valley relative to india tectonic convergence in the eastern himalaya naga hills and shillong plateau gps data reveal that the brahmaputra valley has broken from the indian plate and rotates clockwise relative to india about a point a few hundred kilometers west of the shillong plateau the gps velocity vectors define two distinct blocks separated by the kopili fault upon which 2 3 mm yr of dextral slip is observed the shillong block between longitudes 89 and 93 e rotating clockwise at 1 15 myr and the assam block from 93 5 e to 97 e rotating at 1 13 myr these two blocks are more than 120 km wide in a north south sense but they extend locally a similar distance beneath the himalaya and tibet a result of these rotations is that convergence across the himalaya east of sikkim decreases in velocity eastward from 18 to 12 mm yr and convergence between the shillong plateau and bangladesh across the dauki fault increases from 3 mm yr in the west to 8 mm yr in the east this fast convergence rate is inconsistent with inferred geological uplift rates on the plateau if a 45 n dip is assumed for the dauki fault unless clockwise rotation of the shillong block has increased substantially in the past 4 8 myr such acceleration is consistent with the reported recent slowing in the convergence rate across the bhutan himalaya the current slip potential near bhutan based on present day convergence rates and assuming no great earthquake since 1713 a d is now 5 4 m similar to the slip reported from alluvial terraces that offsets across the main himalayan thrust and sufficient to sustain a mw 8 0 earthquake in this area

in situ development of high elevation low relief landscapes via duplex deformation in the eastern himalayan hinterland bhutan prior studies have proposed tectonic and climatic mechanisms to explain surface uplift throughout the bhutan himalaya while the resulting enigmatic low relief landscapes elevated above deeply incised canyons are a popular setting to test ideas of interacting tectonic and climatic forces when and why these landscapes formed is still debated we test the idea that these landscapes were created by a spatially variable and recent increase in rock uplift rate associated with the formation of structural duplexes at depth we utilize a new suite of erosion rates derived from detrital cosmogenic nuclide techniques geomorphic observations and a landscape evolution model to demonstrate the viability of this hypothesis low relief landscapes in bhutan are eroding at a rate of 70 m ma while basins from surrounding steep landscapes yield erosion rates of 950 m ma demonstrating that this portion of the range is in a transient period of increasing relief applying insights from our erosion rates we explore the influence of an active duplex on overlying topography using a landscape evolution model by imposing a high rock uplift rate in the middle of a mountain range our simulations show that low relief landscapes with thick alluvial fills form upstream of convex knickpoints as rivers adjust to higher uplift rates downstream a pattern consistent with geologic geomorphic and thermochronometric data from bhutan with our new erosion rates reconstructed paleo river profiles and landscape evolution simulations we show that the low relief landscapes were formed in situ as they were uplifted 800 m in the past 0 8 1 ma

impact of late cretaceous to neogene plate tectonics and quaternary ice loads on supra salt deposits at eastern gluckstadt graben north german basin

rigid indian plate constraints from gps measurements abstract we analyze gps data from 26 sites located on the indian plate and along its boundary the large spatial coverage of the indian plate by these sites and longer data duration helped us in refining the earlier estimates of the euler pole for the indian plate rotation our analysis suggests that the internal deformation of the indian plate is very low

characterizing the chemical containment properties of the deep geosphere water rock interactions in relation to fracture systems within deep crystalline rock in the tono area japan

a new kinematic evolutionary model for the growth of a duplex an example from the rangit duplex sikkim himalaya india abstract the lesser himalayan duplex lhd is a prominent structure through much of the lesser himalayan fold thrust belt in the darjeeling sikkim himalaya a component of the lhd is exposed in the rangit window as the rangit duplex rd the rd consists of ten horses of the upper lesser himalayan sequence gondwana buxa upper daling the duplex varies from hinterland dipping in the north through an antiformal stack in the middle to foreland dipping in the south the ramgarh thrust rt is the roof thrust and based on a balanced cross section the main himalayan sole thrust is the floor thrust at a depth of 10 km and with a dip of 3 5 n retrodeformation suggests that the rd initiated as a foreland dipping duplex with the early ramgarh thrust as the roof thrust and the rt as the floor thrust the rt became the roof thrust during continued duplexing by a combination of footwall imbrication and concurrent rt reactivation this kinematic history best explains the large translation of the overlying mct sheets the restoration suggests that rd shortening is 125 km and the original gondwana basin extended 142 km northward of its present northernmost exposures within the window

crustal structure of the darjeeling sikkim himalaya and southern tibet analysis of data from nine temporary broadband seismic stations operated across west bengal and sikkim along with publicly available data from seismographs in the surrounding region provides the first image of the descending indian plate beneath the darjeeling sikkim himalaya the down going indian crust is imaged by receiver function common conversion point stacking using data from 32 sites in combination with more detailed analyses from simultaneous modelling of receiver function data and rayleigh wave group velocity dispersion at 13 stations compared to locations farther south on the indian shield our southernmost station shows evidence for thickened crust beneath the mahanadi rift basin with a possible mafic basal layer north of the mahanadi rift the indian moho is 38 km deep below the archean terranes of the northeast part of the indian shield the moho then dips gently northward beneath the himalayan foreland basin reaching a depth of 44 48 km below the himalayan foothills below sikkim the moho continues to deepen but there are indications of secondary structures in the receiver function image and modelling results suggesting some imbrication of the crust as it flexes downward the crust thickens further beneath the greater himalaya and southern tibet reaching depths of 65 70 km below the southern tibet detachment std below the lhasa terrane north of the std a double discontinuity exists with interfaces at 55 60 km and 80 km depth there is a significant reduction in the average shear wave velocity of the crystalline crust between sites to the south of and on the himalayan foreland basin and sites in the himalaya and to the north below the himalaya and southern tibet the p to s conversion ps has a lower amplitude compared to that observed at sites on the undeformed indian shield this decrease in amplitude of the moho ps phase could arise from a lower impedance contrast across the crust mantle boundary or from scattering due to deformation of the crust and moho a coherent negative arrival beneath the darjeeling sikkim himalaya indicate the presence of a low velocity zone lvz possibly associated with the main himalayan thrust this lvz can be traced beneath the darjeeling sikkim himalaya but disappears beneath the greater himalaya

on the use of dislocations to model interseismic strain and stress build up at intracontinental thrust faults creeping dislocations in an elastic half space are commonly used to model interseismic deformation at subduction zones and might also apply to major intracontinental thrust faults such as the main himalayan thrust here we compare such models with a more realistic 2 d finite element model that accounts for the mechanical layering of the continental lithosphere and surface processes and that was found to fit all available constraints on interseismic and long term surface displacements these can also be fitted satisfactorily from dislocation models the conventional back slip model commonly used for subduction zones may however lead to a biased inference about the geometry of the locked portion of the thrust fault we therefore favour the use of a creeping buried dislocation that simulates the ductile shear zone in the lower crust a limitation of dislocation models is that the mechanical response of the lithosphere to the growth of the topography by bending of the elastic cores and ductile flow in the lower crust cannot be easily introduced fortunately these effects can be neglected because we may assume to first order a stationary topography moreover we show that not only can dislocation models be used to adjust surface displacements but with some caution they can also provide a physically sound rationale to interpret interseismic microseismicity in terms of stress variations

evidence of interseismic coupling variations along the bhutan himalayan arc from new gps data although the first order pattern of present day deformation is relatively well resolved across the himalayas irregular data coverage limits detailed analyses of spatial variations of interseismic coupling we provide the first gps velocity field for the bhutan himalaya combined with published data these observations show strong east west variations in coupling between central and eastern bhutan in contrast with previous estimations of first order uniform interseismic coupling along the himalayan arc we identify significant lateral variations in western and central bhutan the fully coupled segment is 135 155 km wide with an abrupt downdip transition whereas in eastern bhutan the fully coupled segment is 100 120 km wide and is limited updip and downdip by partially creeping segments this is the first observation of decoupling on the upper ramp along the himalayan arc with important implications for large earthquake surface rupture and seismic hazard

estimates of interseismic deformation in northeast india from gps measurements abstract estimates of interseismic deformation in northeastern india based on gps measurements at eight permanent stations 2003 2006 and six campaign sites 1997 2006 are presented here the euler pole of rotation of indian tectonic plate in itrf2000 determined from the present data set is located at 51 7 0 5 n 15 1 1 5 e with angular velocity of 0 469 0 01 myr 1 the results show that there is a statistically insignificant present day active deformation within the shillong plateau and in the foreland spur north of the plateau in the brahmaputra valley convergence rate of the northeastern gps sites with respect to the igs station lhasa along baselines that are normal to the himalayan arc in this region is 16 0 5 mm yr this represents the arc normal indo eurasian convergence rate across the northeastern boundary similar to arc normal convergence rates determined in central nepal along the himalayan arc however unlike central nepal in the arunachal himalaya the 16 mm yr shortening is distributed between the lesser as well as higher and tethyan himalayas baselines between sites on the indo burmese fold and thrust belt ibftb and shillong plateau indicate variations in the shortening rate from 1 5 mm yr on the tripura mizoram salient trs south of the plateau to 6 mm yr in the imphal recess ir to the east and 8 mm yr in naga salient ns to the northeast this suggests that the deformation in the ibftb is segmented into n s blocks along e w transverse zones exhibiting dextral slip between ns ir and sinistral slip between ir and trs baselines between the ibftb sites also show 10 0 6 mm yr convergence pointing to the existence of an active transverse zone between aizawl and imphal

the evolution of the north german basin and the metamorphism of the lower crust in an integrated analysis metamorphic processes in the accreted crust potential field anomalies temperature field and subsidence history are summarized into a model for the development of the north german basin the model integrates observed phenomena such as the high nitrogen content in natural gases in permian sandstone reservoirs and the structure of the crust with model calculations rock density increase subsequent volume reduction and loss of volatiles during metamorphism lead to a depression at the surface of the earth the load of the sediments which will be deposited in the depression enhances the subsidence and the ongoing metamorphism the model provides an alternative to the application of existing tectonic stretching models for the explanation of the subsidence of sedimentary basins

some aspects of the late and post variscan development of the northwestern german basin abstract the crust of northern germany can be subdivided into three provinces that are evident by differences in crustal density seismic velocity reflectivity magnetic characteristics thermal history and electric conductivity these provinces are limited by the elbe river and the northern foothills of the mittelgebirge during the pre and post variscan evolution the tectonic setting of northern germany has changed repeatedly each of the three recognized basement provinces differs in the timing of basement consolidation caledonian variscan the sequence of basin development during permian mesozoic and cenozoic times and the timing and intensity of magmatic activity permian cretaceous cenozoic

features of fractures forming flow paths in granitic rock at an lpg storage site in the orogenic field of japan the biggest underground storage facility for liquefied petroleum gas lpg in the world has been constructed in sub seabed cretaceous granitic rock located in the seto inner sea area of western japan this lpg facility is being operated using a water curtain system in order to control the flow of groundwater and pore pressure and thereby ensure long term safe lpg storage to design this water curtain system it was essential to understand the hydrological and structural features of flow path fp fractures in the granitic host rock therefore detailed fp mapping structural characterization and grouting after hydrological examination were carried out as a result two types of fp were distinguished in the host granitic rock one is a planar type fracture which constitutes a major fp at the site hydrologically the fractures of this type are well connected and readily controlled by grouting the other type is a micro sheeting type fracture which is characterized by an assemblage of micro fractures fractures of this second type were formed under an unloading stress field while the granitic body underwent uplift however these fractures have quite low groutability owing to the poor connectivity of their micro pores the physical characteristics of the fracture fillings e g calcite within both kinds of fps reflect the processes of fp formation and evolution of the host rock the structural and mineralogical features of the fps can be explained by the development of fractures and fluid circulation due to the relatively rapid uplift of the granite during orogenesis the two kinds of fp can be considered typical of groundwater conductive features in an orogenic stress field inevitably such features will be encountered in other plutons formed at continental margins

indentor corner tectonics in the yakutat st elias collision constrained by gps the yakutat st elias collision in se alaska and adjacent canada represents a prime example of present day tectonics associated with an indentor corner its eastern syntaxis is marked by high exhumation a sharp structural bend and strain concentration at the transition from shortening to oblique transpression here we present gps velocity and strain rate fields that cover the syntaxis including 11 new stations in the core of the st elias mountains these data are corrected for transient deformation glacial isostatic adjustment and postseismic and interseismic loading to produce residual velocities and strain rates representative of long term tectonics the main features of these velocity and strain rate fields are a peak in strain rates strain knot in the syntaxis at the junction between the main fault systems and a rapid rotation from convergence parallel to convergence normal orientations of the velocities and shortening axes around the syntaxis leading to shortening across the southern denali fault these features are consistent with the strain and tectonic patterns expected near an indentor corner at the transition from shortening to transpression with a combination of diffuse and localized deformation the gps velocities and strain rates show diffuse deformation around the syntaxis from pure convergence parallel shortening in the orogenic wedge to oblique extension that accommodates the strain rotation at the front of the syntaxis this indentor corner model also results in a near zero strike slip rate on the southern denali fault and shows no clear evidence for a throughgoing fault hypothesized to link the fairweather and totschunda faults

long term growth of the himalaya inferred from interseismic insar measurement the rise and support of the 5000 m topographic scarp at the front of indian eurasian collision in the himalaya involves long term uplift above a mid crustal ramp within the main himalayan thrust mht system locking of the shallower portion of the flat ramp flat during the interseismic period also produces transient uplift above the transition zone however spatial and temporal relationships between permanent and transient vertical deformation in the himalaya are poorly constrained leading to an unresolved causal relationship between the two here we use interferometric synthetic aperture radar insar to measure interseismic uplift on a transect crossing the whole himalaya in central nepal the uplift velocity of 7 mm yr at the front of the annapurna mountain range is explained by an 18 21 mm yr slip rate on the deep shallow dipping portion of the mht with full locking of the mid crustal ramp underlying the high himalaya the transient uplift peak observed by insar matches spatially with the long term uplift peak deduced from the study of trans himalayan river incision although models of the seismic cycle involving thrusting over a ramp of fixed geometry predict an 20 km separation between the two peaks we argue that this coincidence indicates that today s mid crustal ramp in central nepal is located southward with respect to its average long term location suggesting that mountain growth proceeds by frontward migration of the ramp driven by underplating of material from the indian plate under the himalaya

seismotectonics of bhutan evidence for segmentation of the eastern himalayas and link to foreland deformation abstract the instrumental record of bhutan is characterized by a lower seismicity compared to other parts of the himalayan arc to understand this low activity and its impact on the seismic hazard a seismic network was installed in bhutan for 22 months between 2013 and 2014 recorded seismicity earthquake moment tensors and local earthquake tomography reveal along strike variations in structure and crustal deformation regime a thickened crust imaged in western bhutan suggests lateral differences in stresses on the main himalayan thrust mht potentially affecting the interseismic coupling and deformation regime sikkim western bhutan and its foreland are characterized by strike slip faulting in the indian basement strain is particularly localized along a nw se striking mid crustal fault zone reaching from chungthang in northeast sikkim to dhubri at the northwestern edge of the shillong plateau in the foreland the dextral dhubri chungthang fault zone dcf causes segmentation of the indian basement and the mht between eastern nepal and western bhutan and connects the deformation front of the himalaya with the shillong plateau by forming the western boundary of the shillong block the kopili fault the proposed eastern boundary of this block appears to be a diffuse zone of mid crustal seismicity in the foreland in eastern bhutan we image a seismogenic flat portion of the mht which might be either related to a partially creeping segment or to increased background seismicity originating from the 2009 m w 6 1 earthquake in western central bhutan clusters of micro earthquakes at the front of the high himalayas indicate the presence of a mid crustal ramp and stress buildup on a fully coupled mht the area bounded by the dcf in the west and the seismogenic mht in the east has the potential for m7 8 earthquakes in bhutan similarly the dcf has the potential to host m7 earthquakes as documented by the 2011 sikkim and the 1930 dhubri earthquakes which were potentially associated with this structure

erosion rates of the bhutanese himalaya determined using in situ produced 10be abstract western bhutan provides an ideal setting to understand the interplay between uplift erosion and fluvial sediment transport in an active mountain environment using in situ produced 10 be 49 samples and 26 al 5 samples in fluvial sediment from nested catchments throughout the puna tsang chhu drainage basin we examine erosion rates in different geomorphic environments including two high relief regions a glacierized zone in the north and a high rainfall zone in the south as well as remnants of an uplifted lower relief paleosurface between them the erosion rates roughly mirror this north south zonation lower rates avg 388 32 m my 1 n 16 prevail in the low relief zone roughly coinciding with lower relief terrain where mean annual precipitation is 1500 mm yr 1 the highest rates avg 956 160 m my 1 n 13 are in the south 27 10 27 35 n where rainfall is 4000 mm yr 1 high rates avg 700 62 m my 1 n 15 also occur in the northern glacierized region 27 70 28 10 n all 49 purified mineral separates used in this study contain measurable amounts of native 9 be up to 900 g violating the assumption of negligible 9 be that is commonly made in the isotope dilution method used to quantify 10 be to correct for this native 9 be we use high precision replicate measurements of 9 be in each sample to calculate 10 be concentrations from measured isotopic ratios neglecting native 9 be would have led to erosion rate overestimates from 400 the pervasive nature of 9 be in these samples underscores the importance of quantifying the native 9 be concentration in mineral separates used for cosmogenic 10 be analysis

crustal structure of the himalayan orogen at 90 east longitude from project indepth deep reflection profiles international deep profiling of tibet and the himalaya indepth deep seismic reflection profiles show that the indian lithosphere is underthrusting the central himalaya along a gently north dipping decollement that is traceable northward beneath the tethyan belt to 28 6 n and to a depth of about 45 km the decollement carries in its hanging wall a near crustal thickness slice of internally deformed indian continental basement and cover represented in outcrop by the greater himalayan belt and structurally overlying tethyan belt geometric relationships suggest that the decollement probably ramps downward beneath the northern tethyan belt to near the base of the crust and that the hanging wall crustal slice was detached from indian mantle lithosphere that presently underlies southern tibet to the north the north himalayan anticlinorium kangmar dome appears to be a large duplex ramp anticline in the hanging wall of the decollement the south tibetan detachment appears to have been imaged in two areas in the wagye la area it appears to follow the tethyan belt greater himalayan belt contact northward in the subsurface and to have been folded over the kangmar dome in the zherger la area it appears to have been active relatively recently as a 30 north dipping normal fault that cuts deeply into the greater himalayan belt allochthon palinspastic reconstruction indicates a minimum of about 326 km of shortening of the indian basement across the himalaya since the initiation of the main central thrust hence indian continental lithosphere largely stripped of its overlying crust can extend northward beneath the tibetan plateau to at least 32 n where earthquake seismological observations show that the properties of the upper mantle change markedly e g mcnamara et al 1995 taken together the seismic reflection and earthquake seismological observations lend support for the view that the indian mantle lid mechanically underplates roughly the southern half of the tibetan plateau the indepth reflection data do not show that indian crust attached to this lithosphere extends north of southernmost tibet kangmar dome nor do they negate this possibility similarly the reflection data do not yield direct evidence for or against lower crustal subduction beneath the himalaya

subduction initiation and the rise of the shillong plateau abstract discrepancies between geodetically and geologically estimated thrust fault slip rates are generally viewed as a methodological problem even when slip rate is steady over geological time a discrepancy may exist because each method is sensitive to different deformation processes however this offers a tool to estimate the partitioning of convergence between footwall and hanging wall deformation and therefore a way to discriminate among orogenic styles here we investigate one such discrepancy for the shillong plateau a basement cored contractional orogen within the himalayan foreland basin using a regional block model to explain the modern geodetic velocity field and explicit uncertainty analysis of the geologic rates we show that this discrepancy cannot be reconciled simply by invoking uncertainties in individual methods our results indicate that the shillong plateau is not an ongoing forward break of the bhutan himalayas as was believed until recently instead the observed inter plate convergence and plateau uplift in this region may be driven primarily by an attempt of the negatively buoyant indian passive margin lithosphere the surma basin south of the plateau to initiate subduction as a result the uplift history of the plateau which constrains the geologic rate is significantly lower than expected given the geodetic convergence rate we propose that this convergence is largely accommodated by the transport of the footwall into the mantle this geodynamic scenario has important regional seismotectonic implications 1 the cold and brittle sinking passive margin may have enabled the deep extent 30 km and therefore large magnitude of the mw 8 shillong earthquake of 1897 2 the collapse of the indian lithosphere into the mantle may have created the anomalously deep 20 km surma basin and 3 this subsidence may also drive accelerated post miocene westward propagation of the indo burman wedge we propose that the shillong plateau is the only modern example of passive margin collapse and can serve as a natural laboratory to study the earliest phase of subduction

evidence for a wide and gently dipping main himalayan thrust in western bhutan the main himalayan thrust mht is the source of great earthquakes that have been documented along the range its geometry is a key parameter that influences accommodation of tectonic loading and earthquake magnitudes along the himalayan arc although seismic images are available for both the western and the central part of the range this geometry remains poorly constrained for the bhutanese himalayas here we address this issue using a 10be cosmogenic nuclides denudation transect across western bhutan we observe a wide low denudation rate domain between 50 km and 110 km from the front followed by a strong northward increase using a joint inversion of denudation rates gps data and holocene uplift rates we interpret this pattern as a consequence of a flat ramp transition along the mht compared to central nepal and sikkim this location of the ramp suggests a wider decollement with implications for greater seismogenic potential of the mht in western bhutan

the geological evolution of the tibetan plateau the geological evolution of the tibetan plateau is best viewed in a context broader than the india eurasia collision zone after collision about 50 million years ago crust was shortened in western and central tibet while large fragments of lithosphere moved from the collision zone toward areas of trench rollback in the western pacific and indonesia cessation of rapid pacific trench migration 15 to 20 million years ago coincided with a slowing of fragment extrusion beyond the plateau and probably contributed to the onset of rapid surface uplift and crustal thickening in eastern tibet the latter appear to result from rapid eastward flow of the deep crust probably within crustal channels imaged seismically beneath eastern tibet these events mark a transition to the modern structural system that currently accommodates deformation within tibet

characterizing the main himalayan thrust in the garhwal himalaya india with receiver function ccp stacking abstract we use common conversion point ccp stacking of ps receiver functions to image the crustal structure and moho of the garhwal himalaya of india our seismic array of 21 broadband seismometers spanned the himalayan thrust wedge at 79 80 e between the main frontal thrust and the south tibet detachment in 2005 2006 our ccp image shows the main himalayan thrust mht the detachment at the base of the himalayan thrust wedge with a flat ramp flat geometry seismic impedance contrasts inferred from geologic cross sections in garhwal imply a negative impedance contrast velocity decreasing downward for the upper flat located beneath the lower himalaya and a positive impedance contrast velocity increasing downward for the ramp located beneath the surface trace of the munsiari thrust or mct i at the lower flat located beneath the higher himalaya spatially coincident measurements of very high electrical conductivities require the presence of free fluids and we infer a negative impedance contrast on the mht caused by ponding of these fluids beneath the detachment our seismic image indicates that the upper flat of the mht is 10 km below sea level and dips north at 2 connecting to a mid crustal ramp which is 10 km high and dips at 16 the lower flat is 20 25 km below sea level and dips at 4 the main central thrust mct appears as a negative impedance contrast dipping at 16 the moho is nearly horizontal at 35 45 km depth beneath the sub himalaya and lower himalaya deepening to 50 km or more beneath the higher himalaya this depth is 10 25 km shallower than in the nw indian himalaya and 5 10 km shallower than in central nepal requiring significant along strike variations in crustal thickness the observed thickness of subducted indian crust in garwhal is 20 28 km

revisiting the structural setting of the glueckstadt graben salt stock family north german basin abstract reprocessing of seismic data of a salt stock family from the north german basin provided new insights into the structural evolution of this area the common reflection surface crs stack technique was applied to reprocess the reflection data acquired by the hydrocarbon industry in the 1980s due to the low fold of these data and the complex geology in the study area severe imaging challenges were encountered when the data were initially processed using conventional cmp stack the crs stack technique is particularly suited for low fold data in complex areas since it builds physically correct super gathers even if dipping structures are present this leads to a considerably improved signal to noise ratio in the crs stack compared to cmp stack sections moreover the crs stack parameters obtained during the stack form the foundation for a robust reflection tomography used for velocity model building these models allowed the application of pre stack and post stack depth migration the obtained depth images provided structural details not seen before motivating an alternative view on the structural setting of the area the image of the jurassic salt plug indicates tectonics similar to observations in the allertal region where reverse faulting plays a major role in the evolution of the salt structures as a consequence shortening of the mesozoic strata was included into the revised interpretation of the glueckstadt graben area the new depth images also allowed an updated look on the petroleum system of this graben which indicates new possible exploration targets

gps derived deformation rates in northwestern himalaya and ladakh deformation rates derived from gps measurements made at two continuously operating stations at leh 34 1 n 77 6 e and hanle 32 7 n 78 9 e and eight campaign sites in the trans himalayan ladakh spanning 11 years 1997 2008 provide a clear picture of the kinematics of this region as well as the convergence rate across northwestern himalaya all the ladakh sites move 32 34 mm year ne in the itrf2005 reference frame and their relative velocities are 13 16 mm year sw in the indian reference frame and 19 mm year w with reference to the lhasa igs station in southeastern tibet the results indicate that there is no statistically significant deformation in the 200 km stretch between the continuous sites leh and hanle as well as between leh and nubra valley sites along the karakoram fault whereas the sites in and around the splayed karakoram fault region indicate surface deformation of 2 5 mm year campaign sites along the karakoram fault zone indicate a fault parallel surface motion of 1 4 2 5 mm year in the tangste and western panamik segment of the karakoram fault which quantifies the best possible gps derived dextral slip rate of 3 mm year along this fault during this 11 year period baselines of ladakh sites show convergence rates of 15 18 mm year with respect to south india and 12 15 mm year with respect to delhi in north india and almora in the himalaya 400 km north northeast of delhi these constitute an arc normal convergence of 12 15 mm year across the western himalaya which is consistent with arc normal convergence all along the himalayan arc from west to east baseline extension rates of 14 16 mm year between lhasa and ladakh sites are consistent with the east west extension rate of tibetan plateau

a dislocation model of strain accumulation and release at a subduction zone strain accumulation and release at a subduction zone are attributed to stick slip on the main thrust zone and steady aseismic slip on the remainder of the plate interface this process can be described as a superposition of steady state subduction and a repetitive cycle of slip on the main thrust zone consisting of steady normal slip at the plate convergence rate plus occasional thrust events that recover the accumulated normal slip because steady state subduction does not contribute to the deformation at the free surface deformation observed there is completely equivalent to that produced by the slip cycle alone the response to that slip is simply the response of a particular earth model to embedded dislocations for a purely elastic earth model the deformation cycle consists of a coseismic offset followed by a linear in time recovery to the initial value during the interval between earthquakes for an elastic viscoelastic earth model elastic lithosphere over a viscoelastic asthenosphere the postearthquake recovery is not linear in time records of local uplift as a function of time indicate that the long term postseimic recovery is approximately linear suggesting that elastic earth models are adequate to describe the deformation cycle however the deformation predicted for amore simple elastic half space earth does not reproduce the deformation observed along the subduction zones in japna at all well if stick slip is restricted to the main thrust zone as recognized earlier by shimazaki seno and kato the uplift profiles could be explained if stick slips were postulated to extend along the plate interface beyond the main thrust zone to a depth of perhaps 100 km but independent evidence suggests that stick slip at such depths if unlikely less

postseismic deformation following the 2015 mw7 8 gorkha nepal earthquake new gps data kinematic and dynamic models and the roles of afterslip and viscoelastic relaxation we report global positioning system gps measurements of postseismic deformation following the 2015 mw7 8 gorkha nepal earthquake including previously unpublished data from 13 continuous gps stations installed in southern tibet shortly after the earthquake we use variational bayesian independent component analysis vbica to extract the signal of postseismic deformation from the gps timeseries revealing a broad displacement field extending 150 km northward from the rupture kinematic inversions and dynamic forward models show that these displacements could have been produced solely by afterslip on the main himalayan thrust mht but would require a broad distribution of afterslip extending similarly far north this would require the constitutive parameter a b to decrease northward on the mht to 0 05 mpa an extreme sensitivity of creep rate to stress change and seems unlikely in light of the low interseismic coupling and high midcrustal temperatures beneath southern tibet we conclude that the northward reach of postseismic deformation more likely results from distributed viscoelastic relaxation possibly in a midcrustal shear zone extending northward from the seismogenic mht assuming a shear zone 5 20 km thick we estimate an effective shear zone viscosity of 3 10 3 10 pa s over the first 1 12 postseismic years near field deformation can be more plausibly explained by afterslip itself and implies a b 0 5 1 mpa consistent with other afterslip studies this near field afterslip by itself would have re increased the coulomb stress by 0 05 mpa over 30 of the gorkha rupture zone in the first postseismic year and deformation further north would have compounded this reloading

isotopic and morphological features of fracture calcite from granitic rocks of the tono area japan a promising palaeohydrogeological tool this study aimed to develop a methodology for assessing the hydrochemical evolution of a groundwater system using fracture filling and fracture lining calcite fracture calcite in deep to ca 1000 m granitic rocks of the tono area central japan was investigated by optical and electron microscopy and chemical and isotopic analysis coupled with geological evidence these new data imply 3 main origins for the waters that precipitated calcite 1 relatively high temperature hydrothermal solutions precipitating calcite distinguished by 18osmow from 3 to ca 10 and with 13cpdb from ca 18 to 7 2 seawater probably partly of miocene age which precipitated calcite distinguished by 13cpdb of ca 0 and 18osmow ca 20 3 fresh water with a variable 13cpdb composition but which precipitated calcite distinguished by 13cpdb that was significantly ca 17 data for 14c suggest that at least some of the fresh water calcite formed within the last 50 ka the present day hydrogeological regime in the tono area is also dominated by fresh groundwater however the marine calcite of probable miocene age found at depth has shown no evidence for dissolution and many different calcite crystal forms have been preserved studies of other groundwater systems have correlated similar crystallographic variations with variations in the salinity of coexisting groundwaters when this correlation is applied to the tono observations the calcite crystal forms imply a similar range of groundwater salinity to that inferred from the isotopic data thus the present study suggests that even in presently low salinity groundwater systems calcite morphological variations may record the changing salinity of coexisting groundwaters it is suggested that calcite morphological data coupled with isotopic data could provide a powerful palaeohydrogeological tool in such circumstances

geometry and crustal shortening of the himalayan fold thrust belt eastern and central bhutan we present a new geologic map of eastern and central bhutan and four balanced cross sections through the himalayan fold thrust belt major structural features from south to north include 1 a single thrust sheet of subhimalayan rocks above the main frontal thrust 2 the upper lesser himalayan duplex system which repeats horses of the neoproterozoic cambrian baxa group below a roof thrust shumar thrust carrying the paleoproterozoic daling shumar group 3 the lower lesser himalayan duplex system which repeats horses of the daling shumar group and neoproterozoic ordovician jaishidanda formation with the main central thrust mct acting as the roof thrust 4 the structurally lower greater himalayan section above the mct with overlying tethyan himalayan rock in stratigraphic contact in central bhutan and structural contact above the south tibetan detachment in eastern bhutan and 5 the structurally higher greater himalayan section above the kakhtang thrust cross sections show 164 267 km shortening in subhimalayan and lesser himalayan rocks 97 156 km structural overlap across the mct and 31 53 km structural overlap across the kakhtang thrust indicating a total of 344 405 km of minimum crustal shortening 70 75 our data show an eastward continuation of lesser himalayan duplexing identified in northwest india nepal and sikkim which passively folded the overlying greater himalayan and tethyan himalayan sections shortening and percent shortening estimates across the orogen although minima do not show an overall eastward increase which may suggest that shortening variations are controlled more by the original width and geometry of the margin than by external parameters such as erosion and convergence rates

aseismic plate boundary in the indo burmese wedge northwest sunda arc plate motion crustal deformation and earthquake occurrence processes in the northwest sunda arc which includes the indo burmese wedge ibw in the forearc and the sagaing fault in the backarc are very poorly constrained plate reconstruction models and geological structures in the region suggest that subduction in the ibw occurred in the geological past but whether it is still active and how the plate motion between the india and sunda plates is partitioned between motion in the ibw and sagaing fault is largely unknown recent gps measurements of crustal deformation and available long term rates of motion across the sagaing fault suggest that 20 3 mm yr of the relative plate motion of 36 mm yr between the india and sunda plates is accommodated at the sagaing fault through dextral strike slip motion we report results from a dense gps network in the ibw that has operated since 2004 our analysis of these measurements and the seismicity of the ibw suggest that the steeply dipping churachandpur mao fault in the ibw accommodates the remaining motion of 18 2 mm yr between the india and sunda plates through dextral strike slip motion and this motion occurs predominantly through velocity strengthening frictional behavior i e aseismic slip the aseismic motion on this plate boundary fault significantly lowers the seismic hazard due to major and great interplate earthquakes along this plate boundary

stress transfer and connectivity between the bhutan himalaya and the shillong plateau abstract within the northern indian plate the shillong plateau is a peculiar geodynamic terrane hosting significant seismic activity outboard the himalayan belt this activity is often used as an argument to explain apparent reduced seismicity in the bhutan himalayas although current geophysical and geodetic data indicate that the bhutan himalayas accommodate more deformation than the shillong plateau we aim to quantify the extent to which the two geodynamic regimes are connected and potentially interact through stress transfers we compiled a map of major faults and earthquakes in the two regions and computed co seismic stress transfer amplitudes our results indicate that the bhutan himalayas and the shillong plateau are less connected than previously suggested major earthquakes in either of the two regions mainly affect transverse faults connecting them causing up to 40 bar coulomb stress change however this effect is clearly less on thrust faults of the either region up to 1 bar only the mw 8 25 1897 assam earthquake that affected the shillong plateau did not cause a stress shadow on the main himalayan thrust in bhutan as previously suggested similarly the mw 8 0 5 1714 bhutan earthquake had negligible impact on stress accumulation on thrust faults bounding the shillong plateau furthermore the main process shaping the regional stress patterns continues to be interseismic loading with complex boundary conditions in a diffuse deformation field involving the bengal basin and indo burman ranges while both the bhutan himalayas and the shillong plateau exhibit a compressional regime their stress evolutions are more weakly connected than hypothesized although our modelling suggests lateral increase in stress interactions from west less to east more in the bhutan himalayas a clearer picture will only emerge with better constrained fault geometries slip rates crustal structure and seismicity catalogues in the entire region of distributed deformation

the hecataeus rise easternmost mediterranean a structural record of miocene quaternary convergence and incipient continent continent collision at the african anatolian plate boundary abstract the hecataeus rise represents a plateau like structure adjacent to the southern cyprus margin and directly next to the cyprus eratosthenes seamount convergence zone where incipient continent continent collision is believed to occur based on newly acquired seismic reflection and bathymetric data we report on the miocene to quaternary structural evolution of this yet underexplored sector along the african anatolian plate boundary a period of pre messinian compression has significantly deformed the western and southern part of the plateau area offshore continuation of onshore cyprus lineaments attests the existence of a pre messinian structural link between cyprus and the hecataeus rise owing to its relatively elevated position during the messinian salinity crisis the hecataeus rise experienced wide spread messinian erosion and only local deposition of evaporites which were precipitated within small isolated sub basins post messinian convergence was accommodated along the southeastern flank of the hecataeus rise where ne sw trending anticlinal structures experienced reactivation and significant growth a prominent intra pliocene quaternary unconformity in the northwestern part of the plateau area may correlate with the pliocene pleistocene transition and indicates the near synchronous occurrence of several tectonostratigraphic events we suggest that these events represent a chain of structural and depositional changes initiated by incipient collision of eratosthenes seamount with cyprus and the northwestern corner of the hecataeus rise collision derived uplift of cyprus resulted in vertical separation between cyprus and the hecataeus rise and the development of a prominent unconformity in the northwestern part of the plateau area increasing the slopes adjacent to cyprus facilitated more energetic downslope sediment transport expressed by the development of sediment waves and the evolution of a prominent canyon structure at the northeastern limit of the plateau area

dynamics of prolonged salt movement in the gluckstadt graben nw germany driven by tectonic and sedimentary processes the formation of salt structures exerted a major influence on the evolution of subsidence and sedimentation patterns in the gluckstadt graben which is part of the central european basin system and comprises a post permian sediment thickness of up to 11 km driven by regional tectonics and differential loading large salt diapirs salt walls and salt pillows developed the resulting salt flow significantly influenced sediment distribution in the peripheral sinks adjacent to the salt structures and overprinted the regional subsidence patterns in this study we investigate the geometric and temporal evolution of salt structures and subsidence patterns in the central gluckstadt graben along a key geological cross section the post permian strata were sequentially decompacted and restored in order to reconstruct the subsidence history of minibasins between the salt structures the structural restoration reveals that subsidence of peripheral sinks and salt structure growth were initiated in early to middle triassic time from the late triassic to the middle jurassic salt movement and salt structure growth never ceased but were faster during periods of crustal extension following a phase from late jurassic to the end of the early late cretaceous in which minor salt flow occurred salt movement was renewed particularly in the marginal parts of the gluckstadt graben subsidence rates and tectonic subsidence derived from backstripping of 1d profiles reveal that especially the early triassic and middle keuper times were periods of regional extension three specific types of salt structures and adjacent peripheral sinks could be identified 1 graben centre salt walls possessing deep secondary peripheral sinks on the sides facing away from the basin centre 2 platform salt walls whose main peripheral sinks switched multiple times from one side of the salt wall to the other and 3 graben edge pillows which show only one peripheral sink facing the basin centre

underplating in the himalaya tibet collision zone revealed by the hi climb experiment we studied the formation of the himalayan mountain range and the tibetan plateau by investigating their lithospheric structure using an 800 kilometer long densely spaced seismic array we have constructed an image of the crust and upper mantle beneath the himalayas and the southern tibetan plateau the image reveals in a continuous fashion the main himalayan thrust fault as it extends from a shallow depth under nepal to the mid crust under southern tibet indian crust can be traced to 31 n the crust mantle interface beneath tibet is anisotropic indicating shearing during its formation the dipping mantle fabric suggests that the indian mantle is subducting in a diffuse fashion along several evolving subparallel structures

distribution of present day vertical deformation across the southern alps new zealand from 10 years of gps data 1 we use ten years of gps data from nine continuous and six semi continuous gps stations in a transect across the southern alps to measure rates of relative vertical movement with typical 1 uncertainties of 0 3 0 5 mm yr the estimated vertical rates define a fairly smooth profile across the range with the highest rates of 5 mm yr found near the crest of the mountains and 20 30 km southeast of the alpine fault the distribution of vertical rates supports models based on horizontal velocities from gps surveys in which interseismic coupling on the alpine fault decreases from 100 near the surface to zero by 13 18 km depth

seasonal and long term vertical deformation in the nepal himalaya constrained by gps and grace measurements 1 we analyze continuous gps measurements in nepal southern side of the himalaya and compare gps results with grace observations in this area we find both gps and grace show significant seasonal variations further comparison indicates that the observed seasonal gps height variation and grace derived seasonal vertical displacement due to the changing hydrologic load exhibit very consistent results for both amplitude and phase for continuous gps stations whose observation time span are longer than 3 years the average wrms reduction is 45 when we subtract grace derived vertical displacements from gps observed time series the comparison for annual amplitudes between gps observed and grace derived seasonal displacements also shows consistent correlation the good seasonal correlation between gps and grace is due to the improved gps processing strategies and also because of the strong seasonal hydrological variations in nepal besides the seasonal signal grace also indicates a long term mass loss in the himalaya region assuming no gia effect this mass loss therefore will lead to crustal uplift since the earth behaves as an elastic body we model this effect and remove it from gps observed vertical rates with a 2d dislocation model most gps vertical rates especially in the central part of nepal can be interpreted by interseismic strain from the main himalayan thrust and several exceptions may indicate the complexity of vertical motion in this region and some potential local effects

intraplate deformation of the indian subcontinent 1 while deformation at the earth s surface primarily occurs along tectonic plate boundaries major earthquakes have shaken regions deep within continental interiors three of the largest m 7 5 historic intraplate earthquakes occurred within the indian subcontinent suggesting the possibility of significant intraplate deformation we consider surface velocities determined from new gps data collected at 29 continuous gps stations and 41 survey mode gps stations in india between 1995 and 2007 to find a north south shortening rate of 0 3 0 05 nanostrain yr 1 which may be accommodated by 2 1 mm yr of more localized convergence across central india southward motions at 4 7 mm yr of sites on the shillong plateau in northeast india reflect rapid shortening and high earthquake hazard associated with active thrust faults bounding the plateau the width and magnitude of the elastic strain accumulation field across the himalaya varies little from 76 90 longitude but the strain is more broadly distributed and convergence rates are higher along the eastern 200 km of the range

hydrothermal alteration of deep fractured granite effects of dissolution and precipitation abstract this paper investigates the mineralogical effects of hydrothermal alteration at depth in fractures in granite a fracture accompanied by an alteration halo and filled with clay was found at a depth of 200 m in a drill core through toki granite gifu central japan microscopic observation xrd xrf epma and sxam investigations revealed that the microcrystalline clays consist of illite quartz and pyrite and that the halo round the fracture can be subdivided into a phyllic zone adjacent to the fracture surrounded by a propylitic zone in which fe phyllosilicates are present and a distinctive outer alteration front characterized by plagioclase breakdown the processes that result in these changes took place in three successive stages 1 partial dissolution of plagioclase with partial chloritization of biotite 2 biotite dissolution and precipitation of fe phyllosilicate in the dissolution pores 3 dissolution of k feldspar and fe phyllosilicate and illite precipitation associated with development of microcracks these hydrothermal alterations of the granite proceed mainly by a dissolution precipitation process resulting from the infiltration of hydrothermal fluid along microcracks such infiltration causes locally high mobility of al and increases the ratio of fluid to rock in the alteration halo these results contribute to an understanding of how granitic rock becomes altered in orogenic fields such as the japanese island arc

age of initiation of collision between india and asia a review of stratigraphic data abstract the collision of india with asia is perhaps the most profound tectonic event to have occurred in past 100 ma it is responsible for the uplift of the himalayas and tibetan plateau and has been argued to have been responsible for geological geochemical and climatological consequences of global extent yet the age of initiation of this collision remains poorly constrained the literature is replete with estimates that range from the late cretaceous 65 ma to latest eocene

a three step maximum a posteriori probability method for insar data inversion of coseismic rupture with application to the 14 april 2010 mw 6 9 yushu china earthquake 1 we develop a three step maximum a posteriori probability method for coseismic rupture inversion which aims at maximizing the a posterior probability density function pdf of elastic deformation solutions of earthquake rupture the method originates from the fully bayesian inversion and mixed linear nonlinear bayesian inversion methods and shares the same posterior pdf with them while overcoming difficulties with convergence when large numbers of low quality data are used and greatly improving the convergence rate using optimization procedures a highly efficient global optimization algorithm adaptive simulated annealing is used to search for the maximum of a posterior pdf mode in statistics in the first step the second step inversion approaches the true solution further using the monte carlo inversion technique with positivity constraints with all parameters obtained from the first step as the initial solution then slip artifacts are eliminated from slip models in the third step using the same procedure of the second step with fixed fault geometry parameters we first design a fault model with 45 dip angle and oblique slip and produce corresponding synthetic interferometric synthetic aperture radar insar data sets to validate the reliability and efficiency of the new method we then apply this method to insar data inversion for the coseismic slip distribution of the 14 april 2010 mw 6 9 yushu china earthquake our preferred slip model is composed of three segments with most of the slip occurring within 15 km depth and the maximum slip reaches 1 38 m at the surface the seismic moment released is estimated to be 2 32e 19 nm consistent with the seismic estimate of 2 50e 19 nm

a deforming block model for the present day tectonics of tibet 1 we use gps data from 45 sites across the tibetan plateau surveyed between 1991 and 2001 to study the distribution of strain in that part of the india eurasia collision zone the plateau is cut by a few major rapidly slipping strike slip fault zones with broadly distributed strain between those zones the gps velocities can be fit well by a simple deforming block model that combines uniform strain with the motion of blocks separated by the major known fault zones within the plateau the boundaries of the four blocks in this model correspond to the major rapidly slipping faults a rigid block model with a smaller number of blocks fits the data poorly and can be rejected we estimate that 5 9 0 7 mm yr of extension in the n69 w direction occurs on the yadong gulu rift south of the plateau localized extension may extend as far north as the nyainqentanglha range we find 7 4 0 7 mm yr of right lateral slip on the karakorum jiali fault zone significantly slower than that previously estimated from offset geologic features our deforming block model and a two dimensional single fault screw dislocation model give lower and upper bounds of 4 4 1 1 and 10 3 0 4 mm yr on the slip rate on the kunlun fault respectively comparable in its highest to the long term slip rate observed geologically the distributed deformation is surprisingly uniform over the tibetan plateau qaidam basin and qilian shan and approximates a combination of pure shear and uniaxial contraction with the same axes of maximum contraction n32 e this strain field is a combination of shortening and extension that produces little net dilatation 1 area loss per million years at present the broadly distributed strain most likely represents slip on many faults each with a relatively low slip rate distributed conjugate strike slip faulting is the most plausible mechanism to produce the observed strains as supported by the record of medium to large earthquakes within the plateau the distributed deformation is just as important in the accommodation of the total india eurasia convergence as is slip on the major faults the eastward motion of central tibet is as large as 50 of the convergence rate between india and eurasia however this eastward motion is not motion of a relatively undeforming block bounded by rapidly moving strike slip faults as suggested by past extrusion models instead much of this eastward extrusion is driven by the internal extension of the plateau our inference is in agreement with the model of f shen et al 2001 that suggested east west extension north south contraction and eastward plateau growth dominate the present tectonics of the tibetan plateau

recent contributions of glaciers and ice caps to sea level rise satellite measurements of earth s gravity field show that the mass loss of glaciers and ice caps contributed to sea level rise by approximately 0 4 millimetres per year between 2003 and 2010 the extent to which mass loss from ice covered land areas contributes to sea level rise is not known accurately in part because previous global estimates use different techniques for glaciers ice caps and ice sheets the gravity recovery and climate experiment grace satellite has provided monthly measurements of the global gravity field since 2002 using grace data jacob et al assess regional mass loss between 2003 and 2010 and conclude that mass loss from ice covered land areas contributed almost 1 5 mm per year to the sea level rise estimated mass loss from the high mountains of asia was negligible in contrast to some other reports glaciers and ice caps gics are important contributors to present day global mean sea level rise1 2 3 4 most previous global mass balance estimates for gics rely on extrapolation of sparse mass balance measurements1 2 4 representing only a small fraction of the gic area leaving their overall contribution to sea level rise unclear here we show that gics excluding the greenland and antarctic peripheral gics lost mass at a rate of 148 30 gt yr 1 from january 2003 to december 2010 contributing 0 41 0 08 mm yr 1 to sea level rise our results are based on a global simultaneous inversion of monthly grace derived satellite gravity fields from which we calculate the mass change over all ice covered regions greater in area than 100 km2 the gic rate for 2003 2010 is about 30 per cent smaller than the previous mass balance estimate that most closely matches our study period2 the high mountains of asia in particular show a mass loss of only 4 20 gt yr 1 for 2003 2010 compared with 47 55 gt yr 1 in previously published estimates2 5 for completeness we also estimate that the greenland and antarctic ice sheets including their peripheral gics contributed 1 06 0 19 mm yr 1 to sea level rise over the same time period the total contribution to sea level rise from all ice covered regions is thus 1 48 0 26 mm 1 which agrees well with independent estimates of sea level rise originating from land ice loss and other terrestrial sources6

constraints on himalayan deformation inferred from vertical velocity fields in nepal and tibet spirit leveling data from the nepal himalaya between 1977 and 1990 indicate localized uplift at 2 3 mm yr in the lesser himalaya with spatial wavelengths of 25 35 km and at 4 6 mm yr in the greater himalaya with a wavelength of 40 km leveling data with significantly sparser spatial sampling in southern tibet between 1959 and 1981 suggest that the himalayan divide may be rising at a rate of 7 5 5 6 mm yr relative to central tibet we use two dimensional dislocation modeling methods to examine a number of structural models that yield vertical velocity fields similar to those observed although these models are structurally nonunique dislocation models that satisfy the data require aseismic slip rates of 2 7 mm yr on shallow dipping faults beneath the lesser himalaya and rates of 9 18 mm yr on deep thrust faults dipping at 25 n near the greater himalaya unfortunately the leveling data cannot constrain long wavelength uplift 100 km across the himalaya and unequivocal estimates of aseismic slip in central nepal are therefore not possible in turn the poor spatial density of leveling data in southern tibet may inadequately sample the processes responsible for the uplift of the greater himalaya despite these shortcomings in the leveling data the pattern of uplift is consistent with a crustal scale ramp near the greater himalaya linking shallow northward dipping thrust planes 3 6 beneath the lesser himalaya and southern tibet aseismic slip on the potential rupture surface of future great earthquakes beneath the nepal himalaya south of this ramp appears not to exceed 30 of the total convergence rate between india and southern tibet resulting in an accumulating slip deficit of 13 8 mm yr

use of a regional relict landscape to measure vertical deformation of the eastern tibetan plateau 1 field work and topography analysis show that remnant local areas of a low relief landscape or erosion surfaces are geographically continuous across the southeastern tibetan plateau margin we correlate these remnant surfaces as a paleolandscape that formed at low elevation remnants of this paleolandscape are preserved because incision of the fluvial system has been largely limited to major rivers and principal tributaries and has not yet progressed throughout the entire fluvial network the incomplete adjustment of the fluvial system signals initiation of rapid bedrock incision into a developing plateau margin and erosional denudation is concentrated in the major river channels this interpretation contradicts earlier notions that low gradient regional topography is the product of regional elevation reduction by intense landscape dissection due to the presence of several large southeast flowing rivers the modern altitude of the reconstructed paleolandscape or relict landscape constrains the vertical displacement of the plateau surface in response to crustal thickening and subsequent erosion during the lateral growth of the tibetan plateau regional preservation of the relict landscape is consistent with minor surface disruption by late cenozoic thrust faults and folds and supports a model of distributed lower crustal thickening because significant erosion is limited to narrow river gorges an increase in the plateau elevation due to isostatic rebound is minor therefore we propose that the modern elevation of the relict landscape reflects isostatically compensated thickening of the lower crust

formation of a rain shadow o and h stable isotope records in authigenic clays from the siwalik group in eastern bhutan we measure the oxygen and hydrogen stable isotope composition of authigenic clays from himalayan foreland sediments siwalik group and from present day small stream waters in eastern bhutan to explore the impact of uplift of the shillong plateau on rain shadow formation over the himalayan foothills stable isotope data from authigenic clay minerals 2 m suggest the presence of three paleoclimatic periods during deposition of the siwalik group between 7 and 1 ma the mean 18o value in paleometeoric waters which were in equilibrium with clay minerals is 2 5 lower than in modern meteoric and stream waters at the elevation of the foreland basin we discuss the factors that could have changed the isotopic composition of water over time and we conclude that a the most likely and significant cause for the increase in meteoric water 18o values over time is the amount effect specifically a decrease in mean annual precipitation b the change in mean annual precipitation over the foreland basin and foothills of the himalaya is the result of orographic effect caused by the shillong plateau s uplift the critical elevation of the shillong plateau required to induce significant orographic precipitation was attained after 1 2 ma c by applying scale analysis we estimate that the mean annual precipitation over the foreland basin of the eastern bhutan himalayas has decreased by a factor of 1 7 2 5 over the last 1 3 million years 2018 american geophysical union all rights reserved

interseismic coupling on the main himalayan thrust we determine the slip rate and pattern of interseismic coupling on the main himalayan thrust along the entire himalayan arc based on a compilation of geodetic interferometric synthetic aperture radar and microseismicity data we show that convergence is perpendicular to the arc and increases eastwards from 13 3 1 7 mm yr to 21 2 2 0 mm yr these rates are comparable to geological and geomorphic estimates indicating an essentially elastic geodetic surface strain the interseismic uplift rate predicted from the coupling model closely mimics the topography suggesting that a small percentage of the interseismic strain is permanent we find that the fault is fully locked along its complete length over about 100 km width we don t find any resolvable aseismic barrier that could affect the seismic segmentation of the arc and limit the along strike propagation of seismic ruptures the moment deficit builds up at a rate of 15 1 1 10 19 n m yr for the entire length of the himalaya