late cenozoic deformation along the northwestern continuation of the xianshuihe fault system eastern tibetan plateau the xianshuihe fault system is a highly active left lateral slip fault that has played an important role in accommodating late cenozoic crustal deformation of the eastern tibetan plateau the left lateral displacement on the western portion of the fault system the ganzi fault is 80 km based on geologic and geomorphic markers left lateral movement along the fault may have initiated in middle miocene time 12 ma followed by the intensive brittle left lateral movement in late cenozoic time 2 4 ma lying within the headwater regions of the jinsha yangtze river in the yushu region the northwestern end of the xianshuihe fault system consists of four branches these are from north to south the dangjiang fault the yushu fault the batang fault and the xialaxiu fault both the yushu and dangjiang faults display clear geologic and geomorphic evidence for active left lateral slip movement several offset markers of triassic age along the dangjiang fault suggest 39 km of left lateral slip but the geomorphic evidence along the dangjiang and yushu faults suggests only 16 km and 25 km of left lateral slip respectively both the batang and xialaxiu faults demonstrate clear evidence for normal dip slip by an associated series of e w trending grabens and horsts that absorb 9 km of left lateral movement in early to middle pleistocene time about 32 km of left lateral movement on the fault system was estimated to be absorbed by ne sw shortening along the rugged north yushu block in late neogene time this is interpreted to have formed as a rhomb shaped restraining bend along which the left lateral movement along the northwestern end of the fault system was partially transferred into crustal shortening the westward continuation of the dangjiang fault is marked by an e w trending fault which can be traced westward for 150 km to central tibet where it joins the fenghuo shan thrust belt this thrust belt is interpreted to represent the northwestern continuation of the xianshuihe fault system along which 39 km of the left lateral movement was entirely transferred into the n s shortening it indicates that the left lateral movement within the southeastern part of the tibetan plateau along the fault system either caused by lateral extrusion or by clockwise rotation is largely restricted to the northwestern end of the fault system quaternary extension occurred along the northwestern continuation of the xianshuihe xiaojiang fault was coeval with extension along its southern end indicating that the southeastern margin of the plateau underwent clockwise rotation

an insight into crack density saturation rate and porosity model of the 2001 bhuj earthquake in the stable continental region of western india abstract the 2001 bhuj earthquake mw 7 6 source zone is examined in the light of crack density e saturation rate and porosity parameter using new data set derived from a large aftershock sequence recorded by the gujarat seismic network gsnet during november 2006 december 2009 processes of rupture initiations of the mainshock and its aftershock sequence are better understood by synthesizing the dynamic snapshots of the source zone using the new dataset pattern of crustal heterogeneities associated with high e high and high anomalies at depths varying from 20 km to 25 km is similar to those of earlier study by mishra and zhao 2003 the anomalous zone is found extended distinctly by 50 60 km in the lateral direction indicating the reinforcement of cracks and fractured volume of rock matrix due to long aftershock sequence since 2001 bhuj earthquake in the source area it is inferred that the presence of a fluid filled fractured rock matrix with super saturation may have affected the structural and seismogenic strengths of the source zone and is still contributing significantly to the geneses of earthquakes in and around the source zone anomalous pattern of high e with wider distribution of high indicates the existence of micro cracks in the lower crust while high suggests the cementation of cracks through permeation of residual magma metamorphic fluids into the hypocenter zone the results suggest that the existence of residual fluids in the fractured rock matrix in the mid to lower crust might have played a key role in triggering the 2001 mainshock and is still responsible for its continued long aftershock sequences

influence of neotectonism on geomorphology and depositional architecture of the gandak megafan middle ganga plain india abstract the gandak megafan formed by episodic tilting of tectonic block followed by an eastward shift of the gandak river the study area has been identified with 5 distinct depositional units which were chronologically named as oldest gandak plain osgp old gandak plain olgp gandak terminal fan gtfn i ii and iii an integrated approach including morphometry pedology gpr study and osl dating was adopted to study morphotectonics of the megafan dem of the megafan and anomalies in drainage of the area helped to delineate ne sw trending normal faults which divide the megafan block into 3 tectonic sub blocks present day channels reciprocate the fault movements through anomalies in drainage and change in sinuosity around the faults sinuosity of the gandak chhoti gandak and other small streams daha gandaki and rohini varies from 1 6 4 5 and 3 5 respectively which suddenly increases across faults the concurred variations in longitudinal river profiles and sl index appear to be attributable to the tectonic controls the development of these faults and subsequent tilting of the sub blocks influenced the sedimentary architecture and fluvial geomorphology of the megafan a linear arrangement of natural waterlogs and paleochannels observed in satellite images imply lateral shifting of the gandak river older depositional units osgp and olgp show well developed thick solum formation 2 2 m and 1 9 m respectively comparatively the younger units i e terminal fans show poor to no development of soil with 1 2 m to 0 8 m thick successions osl dates indicate that older and younger units were deposited between 10 7 and 8 5 ka and 5 7 and 1 4 ka respectively the tectonically stable period of 3 ka is also exhibited by non depositional surfaces in soil successions

a review on natural and human induced geohazards and impacts in karst karst environments are characterized by distinctive landforms related to dissolution and a dominant subsurface drainage the direct connection between the surface and the underlying high permeability aquifers makes karst aquifers extremely vulnerable to pollution a high percentage of the world population depends on these water resources moreover karst terrains frequently underlain by cavernous carbonate and or evaporite rocks may be affected by severe ground instability problems impacts and hazards associated with karst are rapidly increasing as development expands upon these areas without proper planning taking into account the peculiarities of these environments this has led to an escalation of karst related environmental and engineering problems such as sinkholes floods involving highly transmissive aquifers and landslides developed on rocks weakened by karstification the environmental fragility of karst settings together with their endemic hazardous processes have received an increasing attention from the scientific community in the last decades concurrently the interest of planners and decision makers on a safe and sustainable management of karst lands is also growing this work reviews the main natural and human induced hazards characteristic of karst environments with specific focus on sinkholes floods and slope movements and summarizes the main outcomes reached by karst scientists regarding the assessment of environmental impacts and their mitigation

seismic signature of the mantle transition zone beneath eastern tibet and sichuan basin abstract the strong interaction between the eastward flow escaping from tibet and the rigid sichuan basin resulted in the rise of the longmenshan however the detailed dynamics in the mantle remains controversial in this study the structure of the mantle transition zone mtz beneath eastern tibet and sichuan basin is investigated using 5080 receiver functions from 51 broadband stations the depth of the 410 km discontinuity is close to the global average except for the longmenshan where the 410 and 660 km discontinuities are found to be depressed by up to 10 25 km and 5 10 km respectively the observed simultaneous depressions of the 410 and 660 km discontinuities distributed along the lms together with proofs from tomography and regional tectonics suggest that asthenospheric flow sinks into the mtz resulting in a high velocity zone as well as variation in the mtz thickness the depressions are not from the traditional clapeyron slopes or temperature variation also the depression of the 410 km discontinuity and the dehydration of wadsleyite are syngenetic both of which originate from the dry mantle flow traveling across the old 410 km interface

the 2019 m w 5 7 changning earthquake sichuan basin china a shallow doublet with different faulting styles the increased seismic activity of the last 10 years in changning county of sichuan province comprised just small mostly ml 5 0 injection induced earthquakes the mw 5 7 earthquake of june 17 2019 is the largest event ever reported there moment tensor of the mainshock was remarkably dominated by a compensated linear vector dipole we resolve its fine structure showing it was a doublet allowing approximation by a thrust and strike slip subevent the mainshock nucleated as thrust faulting which together with the largest aftershocks can be linked with previously known reverse faults favorably oriented to regional stress field contrarily the strike slip segment of the mainshock less favorably oriented was probably facilitated by elevated pore pressure due to previous injections shallow active strike slip faulting not yet mapped in the region is a new feature important for future hazard assessment

nature and tectonic significance of co seismic structures associated with the mw 8 8 maule earthquake central southern chile forearc abstract the mw 8 8 maule earthquake on february 27 2010 affected the central southern chilean forearc of the central andes here we show the results of field investigations of surface deformation associated with this major earthquake observations were carried out within three weeks after the seismic event mostly in the central and northern part of the forearc overlying the rupture zone we provide a detailed field record of co seismic surface deformation and examine its implications on active andean tectonics surface rupture consisted primarily of extensional cracks push up structures fissures with minor lateral displacements and a few but impressive extensional geometries similar to those observed in analogical modeling of rift systems a major group of nw wnw striking fractures representing co seismic extensional deformation is found at all localities these appear to be spatially correlated to long lived basement fault zones the nw striking normal focal mechanism of the mw 6 9 aftershock occurred on march 11 demonstrates that the basement faults were reactivated by the mw 8 8 maule earthquake the co seismic surface ruptures show patterns of distributed deformation similar to those observed in mapped basement involved structures we propose that co seismic reactivation of basement structures play a fundamental role in stress release in the upper plate during large subduction earthquakes the fundamental mechanism that promotes stress relaxation is largely driven by elastic rebound of the upper plate located right above the main rupture zone

push ups fracture patterns and palaeoseismology of the leirubakki fault south iceland abstract field measurements and gps mapping were conducted along the leirubakki fault a 010 trending right lateral strike slip fault located in the holocene lava flows of the south iceland seismic zone because of poor exposures south and north of the holocene lava flow dissected by the fault its length can only be traced for 7 5 km the exposed surface rupture contains fractures that range in size over four orders of a magnitude from the main fault through fault segments 1000 2000 m long fracture arrays 100 250 m long to individual fractures 8 125 m long detailed measurements were made of 63 push ups located at junctions between individual fractures and between fracture arrays and ranging in maximum height from 0 35 to 4 35 m using the push ups the maximum right lateral displacement on the leirubakki fault is estimated at 2 67 m using empirical relationships established globally it is concluded that for a maximum displacement of 2 67 m the true rupture length of the leirubakki fault is around 50 km and that it gave rise to an earthquake of a moment magnitude 7 1

morphometric analysis of three dimensional networks of karst conduits the main idiosyncrasy of a typical karst system is the presence of a three dimensional network of conduits behaving as drains in the system and being responsible of both the quick response of karst springs to rainfall events and the complex distribution of solutes in the system a morphometric analysis of the three dimensional geometry of conduits provides quantitative measures that can be used in a range of applications these morphometric parameters can be used as descriptors of the underground geomorphology they provide information on speleogenesis processes they can be correlated with karst denudation ratios they can be used to control the simulation of realistic stochastic karst networks of conduits and they can be correlated with hydrogeologic behaviour of the karst system the main purpose of this paper is to define describe and illustrate a range of morphometric indexes and morphometric functions that can be calculated nowadays because the availability of three dimensional topographies provided by speleological work and the availability of the computational and graphical power provided by modern computers some of the morphometric parameters describe the existence of preferential directions of karstification others describe the kartification along the vertical and the possible presence of inception horizons other indexes describe the shape complexity of the karstic network whilst other indexes describe spatial variability of the conduit geometry and other parameters give account of the connectivity of the three dimensional network the morphometric analysis is illustrated with a three dimensional karstic network in southern france

aster mapping of limestone formations and study of caves springs and depressions in parts of sultanate of oman caves springs and large depressions of limestone karst formations are becoming more attractive tourist places and have potential importance on socio economic development the present study is a multi scale point of view on limestone karst from the space images to microscopic fabric here the karst features consist of limestone formations of cretaceous albian cenomanian age of tanuf valley and tertiary late paleocene middle eocene age of sur region of parts of sultanate of oman which are mapped in the visible near infrared and shortwave infrared spectral bands of advanced spaceborne thermal emission and reflection radiometer aster using decorrelated stretch image processing technique and the occurrences of caves springs and depressions of the formations in the field were studied the decorrelated rgb images of aster spectral bands 8 3 and 1 discriminated well the limestone formations and associated lithology the limestone formations of tanuf valley natih formations of hajar unit are thick bedded massive shallow marine limestone and clayey limestone which have caves and springs large depressions are studied as collapsed structures at the boundary between abat formations they consist of gray to white marly or micritic limestone with chert nodules and seeb formation of bioclastic limestone calcarenite marl and sandstone of sur region interpretations of limestone formations their occurrences and distributions of caves springs and depressions of these regions are verified and confirmed in the field and studied in the laboratory occurrences of more springs and depressions in the limestone formations of the study sites are interpreted and located on the google earth image the study proved the capability of aster sensor in mapping of limestone formations and recommends the technique to other geographical regions where similar geological questions need to be resolved

teleseismic p wave tomography and mantle dynamics beneath eastern tibet we determined a new 3 d p wave velocity model of the upper mantle beneath eastern tibet using 112 613 high quality arrival time data collected from teleseismic seismograms recorded by a new portable seismic array in yunnan and permanent networks in southwestern china our results provide new insights into the mantle structure and dynamics of eastern tibet high velocity high v anomalies are revealed down to 200 km depth under the sichuan basin and the ordos and alashan blocks low velocity low v anomalies are imaged in the upper mantle under the kunlun qilian and qinling fold zones and the songpan ganzi qiangtang lhasa and chuan dian diamond blocks suggesting that eastward moving low v materials are extruded to eastern china after the obstruction by the sichuan basin and the ordos and alashan blocks furthermore the extent and thickness of these low v anomalies are correlated with the surface topography suggesting that the uplift of eastern tibet could be partially related to these low v materials having a higher temperature and strong positive buoyancy in the mantle transition zone mtz broad high v anomalies are visible from the burma arc northward to the kunlun fault and eastward to the xiaojiang fault and they are connected upward with the wadati benioff seismic zone these results suggest that the subducted indian slab has traveled horizontally for a long distance after it descended into the mtz and return corner flow and deep slab dehydration have contributed to forming the low v anomalies in the big mantle wedge our results shed new light on the dynamics of the eastern tibetan plateau

influence of fluids and magma on earthquakes seismological evidence abstract in this paper we present seismological evidence for the influence of fluids and magma on the generation of large earthquakes in the crust and the subducting oceanic slabs under the japan islands the relationship between seismic tomography and large crustal earthquakes m 5 7 8 0 in japan during a period of 116 years from 1885 to 2000 is investigated and it is found that most of the large crustal earthquakes occurred in or around the areas of low seismic velocity the low velocity zones represent weak sections of the seismogenic crust the crustal weakening is closely related to the subduction process in this region along the volcanic front and in back arc areas the crustal weakening is caused by active volcanoes and arc magma resulting from the convective circulation process in the mantle wedge and dehydration reactions in the subducting slab in the forearc region of southwest japan fluids are suggested in the 1995 kobe earthquake source zone which have contributed to the rupture nucleation the fluids originate from the dehydration of the subducting philippine sea slab the recent 2001 geiyo earthquake m 6 8 occurred at 50 km depth within the subducting philippine sea slab and it was also related to the slab dehydration process a detailed 3d velocity structure is determined for the northeast japan forearc region using data from 598 earthquakes that occurred under the pacific ocean with hypocenters well located with sp depth phases the results show that strong lateral heterogeneities exist along the slab boundary which represent asperities and results of slab dehydration and affect the degree and extent of the interplate seismic coupling these results indicate that large earthquakes do not strike anywhere but only anomalous areas which can be detected with geophysical methods the generation of a large earthquake is not a pure mechanical process but is closely related to physical and chemical properties of materials in the crust and upper mantle such as magma fluids etc

3 d seismic structure of the source area of the 1993 latur india earthquake and its implications for rupture nucleations abstract the latur earthquake mw 6 1 of 29 september 1993 is a rare stable continental region scr earthquake that occurred on a previously unknown blind fault in this study we determined detailed three dimensional 3 d p and s wave velocity vp vs and poisson s ratio structures by inverting the first p and s wave high quality arrival time data from 142 aftershocks that were recorded by a network of temporary seismic stations the source zone of the latur earthquake shows strong lateral heterogeneities in vp vs and structures extending in a volume of about 90 90 15 km3 the mainshock occurred within but near the boundary of a low vp high vs and low zone this suggests that the structural asperities at the mainshock hypocenter are associated with a partially fluid saturated fractured rock in a previously unknown source zone with intersecting fault surfaces this might have triggered the 1993 latur mainshock and its aftershock sequence our results are in good agreement with other geophysical studies that suggest high conductivity and high concentration of radiogenic helium gas beneath the source zone of the latur earthquake our study provides an additional evidence for the presence of fluid related anomaly at the hidden source zone of the latur earthquake in the scr and helps us understand the genesis of damaging earthquakes in the scr of the world

riedel shear structures in the co seismic surface rupture zone produced by the 2001 mw 7 8 kunlun earthquake northern tibetan plateau abstract we present a case study of riedel shear structures related to the co seismic surface ruptures produced during the 2001 mw 7 8 kunlun earthquake in northern tibet which are related to strike slip movement along the kunlun fault field investigations and interpretations of high resolution remote sensing images show that the 2001 co seismic surface ruptures striking wnw ese are mainly characterized by riedel shear structures including t fractures and r y and p shears a left lateral shear sense is indicated to assess the riedel shear fabrics quantitatively we measured the azimuth of 19 455 co seismic surface rupture strands the width of rupture zones at 474 profiles and 336 fold axes of mole track structures using 1 m resolution ikonos and 0 61 m resolution quickbird images acquired soon after the earthquake the analytical results show that i the co seismic surface ruptures are generally concentrated in up to five subparallel sub rupture zones with individual sub rupture zones varying in width from 3 to 350 m generally 1 2 km iii t fractures are mainly developed within the alluvial deposits at counterclockwise angles of 15 40 relative to the general trend of the rupture zone iv p shears are also mainly found in the alluvial deposits but at counterclockwise to clockwise angles of 5 10 relative to the general trend and v y and r shears are developed within both the alluvial deposits and basement rocks mainly representing the reactivation of pre existing fault traces the results demonstrate that the co seismic riedel shear structures are primarily controlled by the local geology during surface rupture formation consistent with the idea that riedel shear structures are common fault patterns within strike slip shear zones and that their development is related to the early stages of fault evolution

new constraints on the structure thermochronology and timing of the ailao shan red river shear zone se asia new structural petrographic and 40ar 39ar data constrain the kinematics of the asrr ailao shan red river shear zone in the xuelong shan xls geochronological data reveal triassic early tertiary and oligo miocene thermal events the latter event 33 26 ma corresponds to cooling during left lateral shear in the fansipan fsp range thrusting of the sapa nappe linked to left lateral deformation and cooling of the fsp granite occurred at 35 ma rapid cooling resumed at 25 29 ma as a result of uplift within the transtensive asrr in the daynuiconvoi dncv foliation trends nw se but is deflected near large scale shear planes stretching lineation is nearly horizontal on steep foliations shear criteria indicate left lateral shear sense zones with flatter foliations show compatible shear senses petrographic data indicate decompression from 6 5 kbar during left lateral shear temperatures 700 c 40ar 39ar data imply rapid cooling from above 350 c to below 150 c between 25 and 22 ma without diachronism along strike along the whole asrr cooling histories show two main episodes 1 rapid cooling from peak metamorphism during left lateral shear 2 rapid cooling from greenschist conditions during right lateral reactivation of the asrr in the nw part of the asrr xls diancang shan we link rapid cooling 1 to local denudations in a transpressive environment in the sw part ailao shan and dncv cooling 1 resulted from regional denudation by zipper like tectonics in a transtensive regime the induced cooling diachronism observed in the ailao shan suggests left lateral rates of 4 to 5 cm yr from 27 ma until 17 ma dncv rocks always stayed in a transtensive regime and do not show cooling diachronism the similarities of deformation kinematics along the asrr and in the south china sea confirms the causal link between continental strike slip faulting and marginal basin opening

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

silurian tectonic sedimentary setting and basin evolution in the sichuan area southwest china implications for palaeogeographic reconstructions abstract silurian black shales are among the most significant hydrocarbon source rocks globally and are widespread across the southern and eastern sichuan basin and adjacent areas their tremendous production potential has been demonstrated by the discovery of self sourced shale gas reservoirs in the jiaoshiba field in the fuling area of the sichuan basin in this study we reconstruct the tectonic and palaeogeographic framework of the silurian sichuan basin analyze the distribution of sedimentary facies and subdivide the sedimentary succession into a number of stages understanding the formation and evolution of the silurian basin is necessary to predict its potential for future hydrocarbon exploration and development and may also help to better understand global palaeoceanographic conditions during this interval the sichuan basin in the silurian period was located along the northwestern margin of the yangtze plate which was itself located on the northern margin of gondwana at a low near equatorial latitude the basin was initially composed of an intracratonic depression surrounded by three structural uplifts forming a semi enclosed shallow sea however the basin experienced intraplate tectonic deformation at an early stage followed by continued flexural subsidence and intracratonic deformation preserved silurian strata comprising the longmaxi shiniulan and hanjiadian formations reflect several depositional stages including 1 slow deposition of the basal black shale of the longmaxi formation in a deep water environment due to a transgressive lag following glacial melting in gondwana the resulting sea level rise and intraplate tectonic activity 2 rapid sedimentation during the later stage of longmaxi deposition 3 deposition of the shiniulan formation on a neritic carbonate platform in the southern of the basin 4 deposition of the siliciclastic hanjiadian formation in a deltaic environment

india eurasia collision chronology has implications for crustal shortening and driving mechanism of plates the motion of the indian plate is determined in an absolute frame of reference and compared with the position of the southern margin of eurasia deduced from palaeomagnetic data in tibet the 2 600 900 km of continental crust shortening observed is shown to have occurred in three different episodes subduction of continental crust intracontinental thrusting and internal deformation and lateral extrusion the detailed chronology of the collision and plate reorganizations in the indian and pacific oceans supports the hypothesis that slab pull is a dominant driving mechanism of plate tectonics

neogene evolution of the himalayan tibetan region constraints from odp site 758 northern ninetyeast ridge bearing on climatic change abstract magnetic susceptibility remanence and lithostratigraphic profiles for the neogene quaternary sequence at site 758 odp leg 121 on the northern ninetyeast ridge show distinct changes dated from biostratigraphy and detailed magnetostratigraphy at 17 5 10 4 10 0 8 8 6 5 5 4 5 1 2 7 2 5 1 9 and 1 2 1 1 ma these magnetic and lithologic changes appear to reflect changes in the supply and character of terrigenous material from the himalayan tibetan region resulting from changes in gradient of the ganges brahmaputra and probably the ancient indus drainage systems the sedimentary changes can be correlated with changes in uplift sensitive markers such as the oceanic 87 sr 86 sr ratio and monsoonal induced upwelling but not clearly so with sealevel variations we interpret these sedimentary changes therefore to primarily reflect changes in the tectonic evolution of the himalayan tibetan region the changes in the distal marine sedimentary record of the northern ninetyeast ridge are compared with isotopic control on the timing of himalayan tibetan tectonic phases and magnetostratigraphic control on their reflection in the proximal siwalik molasse record this comparison indicates that the distal ninetyeast ridge record can be used to detail and to place minimal age constraints on tectonic phases in the wider himalayan region and on evolution of the proximal molasse sequence with a time lag determined for the four earliest changes at less than 1 m y the changes at 17 5 ma and 5 4 5 1 ma can be interpreted in terms of the causative chain enhanced plate motion uplift and sedimentation change climatic change supporting arguments that the late cainozoic global climatic deterioration is driven by uplift of large plateaus such as the himalayan tibetan region and the western cordillera

temperature distribution in karst systems the role of air and water fluxes a better understanding of heat fluxes and temperature distribution in continental rocks is of great importance for many engineering aspects tunnelling mining geothermal research etc this paper aims at providing a conceptual model of temperature distribution in karst environments which display thermal anomalies as compared with other rocks in temperate regions water circulation is usually high enough to drain out completely the geothermal heat flux at the bottom of karst systems phreatic zone a theoretical approach based on temperature measurements carried out in deep caves and boreholes demonstrates however that air circulation can largely dominate water infiltration in the karst vadose zone which can be as thick as 2000 m consequently temperature gradients within this zone are similar to the lapse rate of humid air 0 5 c 100 m 1 yet this value depends on the regional climatic context and might present some significant variations

co seismic riedel shear structures produced by the 2010 mw 6 9 yushu earthquake central tibetan plateau china abstract riedel shear structures are often developed within strike slip fault zones this study focuses on the riedel shear structures within the co seismic strike slip surface rupture zone produced by the 2010 mw 6 9 yushu earthquake in the central tibetan plateau china field surveys and structural analysis of the surface ruptures reveal that the co seismic riedel shear structures are characterized by i tension cracks t fractures ii compression structures mainly mole tracks p shears and iii discrete shear faults r and y shears developed in unconsolidated alluvial deposits along the pre existing left lateral strike slip ganzi yushu fault zone the t fractures generally show a right stepping en echelon pattern in contrast the p and r shears indicate a left stepping en echelon pattern the riedel shears are inclined to the general trend of the co seismic surface rupture zone at mean counterclockwise angles of 41 t fractures and 21 r shears and a mean clockwise angle of 35 for the p shears the present results show that i the co seismic riedel shear structures indicate a left lateral strike slip sense for the seismogenic fault and ii the t fractures and p and r shears are the primary riedel shear structures formed during the early stages of the evolution of a strike slip fault constrained by pre existing geologic structures

heat exchanges in the heterothermic zone of a karst system monlesi cave swiss jura mountains 1 subsurface ice accumulations in temperate karst environments are assumed to be highly sensitive to external climate forcing and therefore represent a favorable setting for studying processes controlling heat exchanges in the heterothermic zone of a karst system air rock water and ice temperatures were measured and complemented by airflow water discharge and cave air humidity data during a case study carried out between 2001 and 2006 at monlesi ice cave in the swiss jura mountains the energy balance of the system could be quantified for an annual cycle and results demonstrate that forced convection which is controlled by the temperature difference between the cave air and the external atmosphere is a driving force for the heat exchange between the cave and the surrounding environment therefore compared to the external mean annual conditions major thermal anomalies are to be expected in the entrance zone of a cave system since this heterothermic zone may extend over several hundreds of meters a better understanding of the mechanisms controlling the subsurface deposition environment represents a major prerequisite for high resolution paleoenvironmental reconstructions from cave deposits

co seismic secondary surface fractures on southeastward extension of the rupture zone of the 2005 kashmir earthquake abstract after the 2005 kashmir earthquake we mapped surface ground fractures in tangdhar uri rajouri and punch sectors and liquefaction features in jammu area lying close to the eastern side of the line of control loc in kashmir india the nw trending ground fractures occurred largely in the hanging wall zone of the southeastern extension of the causative fault in tangdhar and uri sectors the principal compressive stress deduced from the earthquake induced ground fractures is oriented at n10 whereas the causative balakot bagh fault strikes 330 the fault plane solution indicates primarily sw thrusting of the causative fault with a component of strike slip motion the ground fractures reflect pronounced strike slip together with some tensile component the tangdhar area showing left lateral strike slip motion lies on the hanging wall and the uri region showing right lateral strike slip movement is located towards the southeastern extension of the causative fault zone the shear fractures are related to static stress that was responsible for the failure of causative fault the tensile fractures with offsets are attributed to combination of both static and dynamic stresses and the fractures and openings without offsets owe their origin due to dynamic stress in punch rajouri and jammu area which lies on the footwall the fractures and liquefactions were generated by dynamic stress the occurrence of liquefaction features in the out board part of the himalayan range front near jammu is suggestive of stress transfer 230 km southeast of the epicenter the balakot bagh fault bbf the muzaffarabad anticline the rupture zone of causative fault and the zone of aftershocks all are aligned in a 25 km wide belt along the nw se trending regional himalayan strike of kashmir region and lying between the mbt and the riasi thrust murree thrust suggesting a seismogenic zone that may propagate towards the southeast to trigger an earthquake in the eastern part of the kashmir region

geometry of co seismic surface ruptures and tectonic meaning of the 23 october 2011 mw 7 1 van earthquake east anatolian region turkey abstract the 23 october 2011 m w 7 1 usgs 2011a van earthquake was generated by the rupture of a main thrust fault plane striking n60 e and dipping 55 nw with a very small left lateral offset in the western part of the bardakci saray thrust fault zone located in the north of the bitlis zagros suture zone the incompatibly between the subsurface seismologic data and surface deformation data indicates that the fault that generated the earthquake could be blind the main thrust fault plane developed between the northern ercis and southern van continental blocks and indicates that the region is under the influence of a constant nw se pure compressional tectonic regime along with the primary thrust rupture a secondary back thrust fault a left lateral fault with ne strike and a right lateral fault with nw strike occurred in the contraction province additionally the tensional ground cracks that developed on the hanging wall block of the ruptured thrust fault plane due to intra continental collision are either transtensional that mainly fits to left lateral strike slip faulting or extensional deformations on the elevated block

the crustal and upper mantle structures beneath the northeastern margin of tibet abstract teleseismic receiver functions are used to estimate the crustal thickness v p and v p v s or poisson s ratio beneath the northeastern margin of the tibetan plateau surface wave dispersion measurements are combined with teleseismic receiver functions to improve estimates of model parameters a migration method based on a local velocity model is used to image the upper mantle discontinuities according to the location of pierce points of the direct converted phases on the observed receiver functions we estimate the topography of upper mantle discontinuities the thicker crust in the altyn tagh fault hexi corridor basin may indicate the superposition of crusts during the collision between the indian and the eurasian plates beneath tianshui and its neighboring regions in the eastern margin of tibet high v p and high v p v s values close to uplifts of magma and hot springs might result from the upwelling of mantle materials induced by the collision the depressed 410 km discontinuity might be related to the warm temperature below the northeastern margin of tibet we speculate that the mantle flow beneath the eastern margin of tibet may be turning downward and subsiding into the mantle transition zone

detection of cavity migration and sinkhole risk using radar interferometric time series abstract upward migration of underground cavities can pose a major hazard for people and infrastructure either via sudden collapse sinkholes or by eroding the support of building foundations a migrating cavity can cause the collapse of buildings water defense systems or transport infrastructure the main problem for risk assessment is the lack of a priori knowledge on the location of a potentially hazardous cavity here we demonstrate the feasibility of satellite radar interferometry to detect a migrating cavity under the city of heerlen the netherlands leading to foundation instability and the near collapse of a part of a shopping mall in december 2011 we exploit the data archives of four imaging radar satellites between 1992 and 2011 to investigate the dynamics of the area and detect shear strain within the structure of the building time series analysis shows localized differential vertical deformation rates of 3 mm yr during 18 years followed by a dramatic increase of up to 15 mm yr in the last few years these results imply that the driving mechanism of the 2011 near collapse event had a very long lead time and was likely due to a long lasting gradual process such as the upward migration of a cavity

co seismic mole track structures produced by the 2001 ms 8 1 central kunlun earthquake china extensive co seismic mole track structures have been observed along a 400 km long surface rupture zone associated with the 2001 ms 8 1 central kunlun earthquake north tibet the mole track structures appear in an angular ridge pattern which resembles an angular triangle shaped frame and in a bulge pattern forming small flat hillocks the mole tracks are developed within alluvial fans river channels and bajada and form a linked array of structures along the rupture zone the angular ridge structures resulted from flexural slip folding and faulting of frozen alluvial deposits and surface ice whereas bulge type structures developed by squeezing up of unconsolidated to weakly consolidated alluvial sediments the mole tracks generally formed within the co seismic rupture zone due to contraction in the right bend and right stepover areas between sinistral shear faults and are controlled by the pre existing fault and fold structures along the left lateral strike slip kunlun fault

late cenozoic evolution of the eastern margin of the tibetan plateau inferences from 40ar 39ar and u th he thermochronology high topography in central asia is perhaps the most fundamental expression of the cenozoic indo asian collision yet an understanding of the timing and rates of development of the tibetan plateau remains elusive here we investigate the cenozoic thermal histories of rocks along the eastern margin of the plateau adjacent to the sichuan basin in an effort to determine when the steep topographic escarpment that characterizes this margin developed temperature time paths inferred from 40 ar 39 ar thermochronology of biotite multiple diffusion domain modeling of alkali feldspar 40 ar release spectra and u th he thermochronology of zircon and apatite imply that rocks at the present day topographic front of the plateau underwent slow cooling 30 50 c m y coincident with exhumation from inferred depths of 8 10 km at denudation rates of 1 2 mm yr samples from the interior of the plateau continued to cool relatively slowly during the same time period 3 c m y suggesting limited exhumation 1 2 km however these samples record a slight increase in cooling rate from 1 to 3 c m y at some time during the middle tertiary the tectonic significance of this change remains uncertain regardless late cenozoic denudation in this region appears to have been markedly heterogeneous with the highest rates of exhumation focused at the topographic front of the plateau margin we infer that the onset of rapid cooling at the plateau margin reflects the erosional response to the development of regionally significant topographic gradients between the plateau and the stable sichuan basin and thus marks the onset of deformation related to the development of the tibetan plateau in this region the present margin of the plateau adjacent to and north of the sichuan basin is apparently no older than the late miocene or early pliocene 5 12 ma

cooling history of the gongga batholith implications for the xianshuihe fault and miocene kinematics of se tibet abstract using thermochronological data and thermokinematic modeling we constrain the timing of late miocene exhumation of the northern portion of the gongga batholith located in southeast tibet along the xianshuihe fault xf we show that rapid exhumation started in the north of the gongga batholith at 9 ma at a rate of 1 85 km myr and slowed down since 4 ma a magmatic pulse occurring during the early pliocene 4 ma has overprinted the rapid miocene exhumation phase in some parts of the batholith which record mainly early pliocene post magmatic cooling slow exhumation since 4 ma is consistent with the present day lower relief observed in the centre of the batholith which contrasts with the rugged high peaks located to the south we propose that the northern segment of the xf the yalahe fault which is not active at present was active between 9 and 4 ma forming a restraining bend that focused exhumation south of it since 4 ma the selaha and the zheduotang faults form the present day restraining bend south of which the highest part of the massif is located including the gongga shan that rises more than 3000 m above the mean elevation of the plateau in the north of the batholith similar peaks have been removed since the miocene by local relief reduction at high elevations considering that the onset of motion along the xf is contemporaneous with the onset of rapid exhumation recorded along the kangding transect at 9 ma and a total offset of 62 km documented for the xf the average slip rate of the xf is 7 mm yr since 9 ma

co seismic strike slip fault displacement determined from push up structures the selsund fault case south iceland abstract we analysed push up structures along the selsund fault a n s right lateral strike slip fault activated during the 1912 earthquake in the south iceland seismic zone volume changes and syn tectonic collapse affected push ups during the earthquake followed by post seismic gravitational sagging to determine the push up shortening and hence the strike slip fault motion we define a virtual push up structure without volume change and collapse and we compare it with the present day configuration whereas length comparisons are subject to errors volumetric analysis allows determination of shortening through evaluation of the thickness of the deformed layer affected by the push ups we determine a co seismic peak displacement of 2 4 m along the rupture trace this value is consistent with the magnitude 7 of the earthquake based on empirical relationships neglecting volume changes and collapse effects gives underestimated displacement the new method for analysing push up structures thus allows better determination of magnitudes of ancient earthquakes along strike slip faults

determination of cave geometry by using a geoelectrical resistivity inverse model determination of the geometry and the dimensions of a cave is an important factor considered for planning geotechnical archeological speleological studies and quarrying activities in recent years researchers have raised an increasing number of questions related to the shape and size of cavities using 2d geoelectrical resistivity imaging techniques the inverse model is valuable in detecting the location and extent of subterranean cavities in this study a 2d geoelectrical resistivity imaging technique is employed to determine the geometry of a known subterranean cavity the results provided valuable information and demonstrated the effectiveness of the technique for exploring the size of cavities

surface deformation and tectonic background of the 2019 ms 6 0 changning earthquake sichuan basin sw china abstract the june 17 2019 ms 6 0 changning earthquake at a depth of 3 5 km struck the changning anticline fold system no active faults have been observed in the region some studies have attributed the earthquake to the regional shale gas exploitation following the earthquake we conducted a field survey to investigate co seismic surface deformation in the area and observed many surface fractures and uplifted areas our work indicated that the deformation followed a riedel shear pattern the fractures and uplifted areas represent t fractures and s extrusions respectively the observed riedel shear pattern is indicative of left lateral strike slip motion to ascertain the relationship between the riedel shear pattern and regional tectonics we investigated the trends in layer striations and fault scratches the results indicated that there were two stages in the evolution of the anticline in the first stage the principal compressive stress that dominated the original formation of the anticline trended ne sw in the second stage the regional principal compressive stress shifted to the current e w trend generating oblique motion that included reverse and left lateral components we propose that the tectonic stress field in this region had a strong bearing on the focal mechanism of the mainshock and the co seismic surface deformation both the eastward expansion of the xianshuihe area and southeastward expansion of the longmen shan have affected the current changning anticline fold system

uav based remote sensing of the super sauze landslide evaluation and results unmanned aerial vehicles uavs equipped with digital compact cameras can be used to map landslides quickly and at a high ground resolution images taken by a radio controlled mini quad rotor uav of the super sauze france landslide have been used to produce a high resolution ortho mosaic of the entire landslide and digital terrain models dtms of several regions the uav capability for imaging fissures and displacements on the landslide surface has been evaluated and the subsequent image processing approaches for suitably georectifying the data have been assessed for super sauze horizontal displacements of 7 to 55 m between a high resolution airborne ortho photo of may 2007 and a uav based ortho mosaic of october 2008 have been measured fixed areas of persistent deformation have been identified producing fissures of different distributions and orientations comparable to glacial crevasses and relating directly to the bedrock topography the uav has demonstrated its capability for producing valuable landslide data but improvements are required to reduce data processing time for the efficient generation of ortho mosaics based on photogrammetric dtms in order to minimise georeferencing errors

georeferenced thermal infrared images from uav surveys as a potential tool to detect and characterize shallow cave ducts abstract caves are buried geological features of great scientific and engineering interest based on the well known thermal inertia of cave settings with respect to the surface we have tested the use of thermal infrared tir cameras carried by unmanned aerial vehicles uavs to identify and characterize shallow karstic conduits a pilot area was selected in a limestone rock massif from the betic cordillera southern spain at surface this area appears as a doline field with several explored shaft entrances the main and deepest shaft was thermally monitored at different depths showing two well defined seasonal stages i air and temperature stratification in summer and ii upward air flow and temperature homogenization in winter we carried out uav surveys at the expected maximum thermal contrast hours finding out that winter dawns yielded the most distinctive images these images show new warm air exits warm spots apart from the known cave entrances and emphasize some of the main entrances depicting large warmed areas around them which in turn can be related to shallow voids and conduits in the cave system furthermore tir images have been georeferenced using a network of identifiable points that can be transferred from visible orthoimages the resulting tir orthoimage mosaics have allowed us to define a number of quantitative parameters to characterize the warm spots the most important of these parameters are i the characteristic temperature which is the maximum significant temperature of the air escaping from cave openings ii the warmed area which is the area that appears on the tir orthoimage with a temperature greater than the surface temperature mode and iii the average temperature weighted to the affected area the georeferenced tir orthoimages and the derived parameters are a new and very valuable tool for both speleological exploration and engineering purposes

the 2005 qeshm island earthquake iran a link between buried reverse faulting and surface folding in the zagros simply folded belt summary the 2005 november 27 qeshm island earthquake m w 6 0 provides an excellent opportunity to study coseismic deformation in the zagros simply folded belt with synthetic aperture radar interferometry insar typical of reverse faulting in the zagros slip in the qeshm island earthquake did not rupture the surface however ascending and descending track interferograms spanning the earthquake both show an elliptical pattern of surface deformation in the central part of the island we invert the interferometric data to attain a set of source parameters these show 1 m slip on a steep 50 north dipping reverse fault extending from a maximum depth of 8u p to 4 km below the surface limited aeromagnetic data suggests the fault ruptured the sedimentary cover whether its deepest parts also affected the crystalline basement is not clear source parameters from seismic body wave modelling agree with those from the interferometric modelling using the insar derived model we produce a map of coseismic vertical displacements with which we compare the surface structure of the island coseismic uplift is centred on the eastern end of a major anticline which trends e w parallel with the fault the long term growth of this fold may be controlled primarily by repeated earthquakes on this fault however the uplifted region extends to parts of other nearby folds whose long term growth must have other controls moreover a region of coseismic subsidence lies very close to a part of the qeshm island coastline that displays raised beaches evidence of quaternary uplift therefore the link between reverse faulting and surface folding is not wholly evident from this earthquake alone the local structure is complicated by orthogonal fold axes it may take a large earthquake in a simpler structural setting within the zagros to establish convincingly whether a one to one correlation between faulting and folding exists

is there a big mantle wedge under eastern tibet abstract the big mantle wedge bmw model was originally proposed to explain the origin of the intraplate changbaishan volcano in ne china where the subducting pacific slab becomes stagnant in the lower part of the mantle transition zone mtz the bmw is defined as a broad region in the upper mantle and upper part of the mtz overlying the long stagnant pacific slab under eastern tibet prominent low velocity low v anomalies are revealed in the upper mantle whereas an obvious and broad high velocity high v anomaly is imaged in the mtz from the burma arc northward to the kunlunshan fault zone and eastward to the xiaojiang fault zone in addition receiver function analyses clearly illustrate a thickened mtz in a similar area hence we conclude that there is a bmw structure under eastern tibet which can explain the deep origin of the tengchong volcano and generation of large crustal earthquakes in the region the tengchong volcano is caused by hot and wet mantle upwelling in the bmw and fluids from dehydration reactions of the stagnant indian slab in the mtz the 2008 wenchuan earthquake ms 8 0 took place in a transitional belt from the low v songpan ganzi block to the high v sichuan basin suggesting that the occurrence of the wenchuan earthquake was affected by the bmw structure these results shed new light on the mantle structure and dynamics under eastern tibet

atmospheric summer circulation and coastal upwelling in the arabian sea during the holocene and the last glaciation accumulation rates of biogenic and lithogenic components were studied in 39 turbidite free well dated sediment cores from the northern indian ocean to define the proportions of fluvial and eolian input and to reconstruct quaternary patterns of coastal upwelling the majority of dust deposited in the western arabian sea during the holocene about 100 106 t yr 1 is advected from arabia by northwesterly winds which overlie the low level southwest monsoon the glacial increase in dust flux to 160 106 t yr 1 culminated in the northern arabian sea most probably due to i entrainment of dust rich in chlorite dolomite and lithogenic carbonate in the then dry persian gulf and ii a southward shift of the mean position of the southwest monsoon during glacial summer this shift is recorded in reduced accumulation rates of biogenic opal and increased rates of marine carbonate off somalia and oman both the terrigenous and biogenic sediment records show that the northwesterly winds and the southwest monsoon persisted over the last 27 000 yr as well as the asian continental summer heat low however the glacial seasonal time span of the southwest monsoon season was much reduced most likely because of a delay in the seasonal onset of the southwest monsoon

measuring glacier surface temperatures with ground based thermal infrared imaging spatially distributed surface temperature is an important yet difficult to observe variable for physical glacier melt models we utilize ground based thermal infrared imagery to obtain spatially distributed surface temperature data for alpine glaciers the infrared images are used to investigate thermal microscale processes at the glacier surface such as the effect of surface cover type and the temperature gradient at the glacier margins on the glacier s temperature dynamics infrared images were collected at cuchillacocha glacier cordillera blanca peru on 23 25 june 2014 the infrared images were corrected based on ground truth points and local meteorological data for the control points the pearson s correlation coefficient between infrared and station temperatures was 0 95 the ground based infrared camera has the potential for greatly improving glacier energy budget studies and our research shows that it is critical to properly correct the thermal images to produce robust quantifiable data

sagging and collapse sinkholes over hypogenic hydrothermal karst in a carbonate terrain abstract we show that clusters of karst sinkholes can occur on carbonate hypogene karst terrains unlike common doline karst of dissolution origin the studied sinkholes form mainly by sagging and collapse thermal survey osl dating and morphologic analysis during quarrying and excavations are applied to study the sinkholes at the ayyalon karst israel the thermal survey shows the spatial pattern of rising warm water plumes whose temperature is 2 c warmer than the surrounding aquifer water these plumes dissolve the limestone creating large voids and maze caves mass wasting forms surface sinkholes mainly by sagging and collapse both types of deformation often occur within the same depression lack of hydrologic connection between the surface and underground voids constrain drainage and promote rapid accumulation of colluvium dust and pedogenic clays these have filled the sinkholes up to their rim before the late holocene osl dating constrains the rate of sediment accumulation within the sinkholes the average filling rate thickness divided by elapsed time is 47 mm ka 1 for the last 53 4 ka in sinkhole 1 while in sinkhole 2 nesher ramla karst depression the rate is 61 mm ka 1 from 200 to 78 ka and 173 mm ka 1 since 78 ka between 170 and 78 ka sinkhole 2 was intensively used by middle paleolithic hominins the studied sinkholes may be considered as a type locality for hypogene sinkhole terrain on carbonate rocks

crustal heterogeneity in bulk velocity beneath the 2001 bhuj earthquake source zone and its implications in order to resolve an enigmatic issue relating to the existence of fluid related or temperature related anomalies at the mainshock hypocenter of the 2001 bhuj india earthquake m w 7 6 an estimate of the 3d bulk sound velocity structure is made from the inverted high quality p and s arrival times from a total of 368 aftershocks recorded by 12 temporary seismic stations installed following the 2001 bhuj earthquake results reveal strong lateral and vertical heterogeneity in bulk velocity graphic 1 beneath the source zone the 2001 bhuj mainshock and its aftershock source zones are associated with anomalously high bulk sound velocity high graphic 2 indicating high bulk elastic strength of the source rocks at the mainshock hypocenter due to high pore pressures of the fully saturated cracked rocks associated with solute precipitation through the processes of acoustic fluidization and cementation the interpretation of bulk velocity tomograms suggests that the processes of mineral dehydration and permeation of sea surface water through several active quaternary faults down to the deep crust might have contributed to in situ fluid related material heterogeneity in bulk velocity within the fluid filled fractured rock matrix in the paleorift zone at the 2001 bhuj mainshock hypocenter which in turn increased pore pressure lowered the effective stress and brought the system into a brittle failure high graphic 3 in the intersecting fault geometry in the fractured rock matrix at the mainshock hypocenter can be taken as evidence for the strong role of fluids in association with the intraplate earthquake of the indian peninsula 1 embed inline graphic 1 gif 2 embed inline graphic 2 gif 3 embed inline graphic 3 gif

structure and deformational character of strike slip fault zones strike slip fault zones observed either in the field or in model experiments generally consist of several subparallel faults which make these zones complicated in geometry and kinematics the geometry of a strike slip fault or shear zone is dependent on arrangement pinnate or en echelon on step left step or right step and on the rank smaller faults within larger faults of the subparallel fault the relations and interactions of these three factors create a variety of dynamic circumstances and tectonic settings within the strike slip fault zones these include pull aparts in the release area between subparallel faults push ups in the jogs where the subparallel faults overlap and pivotal movements or rotation of single faults along the whole fault zone each kind of tectonic setting is in itself characteristic each setting consists of many subtypes which are controlled chiefly by the geometric parameters of the subparallel faults one of the most important phenomena revealed in the field work is two different kinds of evolution of strike slip fault zones one is the evolution of a zone with a tensile component which is related to the growth of rock bridges and the other of one with a compressional component which develops by the destruction of rock bridges in this paper we discuss on the basis of recent research on four strike slip fault zones in china the essential characteristics of strike slip faults and the possible causes of the observed structural phenomena attention is focussed on the deformation development and distribution of horizontal displacements within strike slip fault zones

outward growth of the tibetan plateau during the cenozoic a review abstract the surface uplift history of the tibetan plateau tp offers a key testing ground for evaluating models of collisional tectonics and holds important implications for processes ranging from global cooling to the onset of the asian monsoon various models have been proposed to reveal the surface uplift history of the tp but controversies remain we evaluate these models using data from sedimentology and stratigraphy structural geology magmatism exhumation and paleoaltimetry studies structural analyses indicate that thrust belts which spread from the central tp outward toward its surrounding margins accommodated most of the india asia convergence and facilitated crustal shortening and thickening in the central tp eocene adakitic rocks located in the qiangtang and the lhasa blocks likely were generated by partial melting of an eclogitic source paleogene 50 30 ma potassic rocks only occur in the qiangtang block whereas late oligocene late miocene 26 8 ma potassic rocks occur both in the qiangtang and lhasa blocks low temperature thermochronologic ages in the central tp are older than 40 35 ma whereas those in the margins are younger than 20 ma mostly late miocene and pliocene pleistocene in age independent paleoaltimetry estimates suggest that the lhasa and qiangtang terranes attained their current elevations during the eocene most likely due to the initial collision between india and lhasa whereas the hoh xil basin area to the north and himalayas to the south were still low even below sea level in the latter case we argue for an inside out growth pattern for the tibetan plateau the tp grew southward and northward from a nucleus of high topography and is likely to continue expanding along the mazar tagh fault to the northwest the kuantai shan hei shan longshou shan to the northeast the longquan shan to the east and the shillong plateau to the south if the northward force of india would not diminished

tomography of the source area of the 1995 kobe earthquake evidence for fluids at the hypocenter seismic tomography revealed a low seismic velocity 5 and high poisson s ratio 6 anomaly covering about 300 square kilometers at the hypocenter of the 17 january 1995 magnitude 7 2 kobe earthquake in japan this anomaly may be due to an overpressurized fluid filled fractured rock matrix that contributed to the initiation of the kobe earthquake

on developing thermal cave detection techniques for earth the moon and mars abstract the purpose of this study is to 1 demonstrate the viability of detecting terrestrial caves at thermal infrared wavelengths 2 improve our understanding of terrestrial cave thermal behavior 3 identify times of day when cave openings have the maximum thermal contrast with the surrounding surface regolith and 4 further our understanding of how to detect caves on earth the moon and mars we monitored the thermal behavior of two caves in the atacama desert of northern chile through this work we identified times when temperature contrasts between entrance and surface were greatest thus enabling us to suggest optimal overflight times the largest thermal contrast for both caves occurred during mid day one cave demonstrated thermal behavior at the entrance suggestive of cold trapping while the second cave demonstrated temperature shifts suggestive of airflow we also collected thermograms without knowing optimal detection times these images suggest both caves may also be detectable during off peak times we suggest cave detection using thermal remote sensing on earth and other planetary objects will be limited by 1 capturing imagery in the appropriate thermal wavelength 2 the size of cave entrance vs the sensor s spatial resolution 3 the viewing angle of the platform in relation to the slope trajectory of the cave entrance 4 the strength of the thermal signal associated with the cave entrance and 5 the time of day and season of thermal image capture through this and other studies we will begin to identify the range of conditions under which caves are detectable in the thermal infrared and thus improve our detection capabilities of these features on earth the moon and mars

hidden sinkholes and karst cavities in the travertine plateau of a highly populated geothermal seismic territory tivoli central italy abstract sinkholes and other karst structures in settled carbonate lands can be a significant source of hazard for humans and human works acque albule the study area of this work is a plio pleistocene basin near rome central italy superficially filled by a large and thick deposit of late pleistocene thermogene travertine human activities blanket large portions of the flat territory covering most evidence from geological surface processes and potentially inducing scientists and public officials to underestimate some natural hazards including those connected with sinkholes to contribute to the proper assessment of these hazards a geomorphologic study of the basin was performed using digital elevation models dems recent aerial photographs and field surveys historical material such as old aerial photographs and past geomorphologic studies both pre dating the most part of quarrying and village building was also used together with memories of the elderly population this preliminary study pointed out the presence of numerous potentially active sinkholes that are at present largely masked by either quarrying or overbuilding where this first study pointed out the apparent absence of sinkholes in areas characterized by high density of buildings a detailed subsurface study was performed using properly calibrated electrical resistivity tomography ert and dynamic penetration measurements dpsh together with some borehole logs made available from the local municipality this second study highlighted the presence of sinkholes and caves that are this time substantially hidden to the resolution of standard methods and materials such as aerial photographs dems and field surveys active sinkhole subsidence in the acque albule basin may explain at least in part the frequent damages that affect numerous buildings in the area the main conclusion from this study is that the mitigation of sinkhole hazard in highly populated areas has to pass through a thorough search of hidden sinkholes that can be masked by the anthropocenic molding and blanketing of the territory for these purposes data from historical pre anthropocene documents as well as where possible subsurface investigations are fundamental

the 2001 bhuj earthquake tomographic evidence for fluids at the hypocenter and its implications for rupture nucleation 1 the january 26 2001 bhuj earthquake mw 7 6 is one of the most catastrophic indian earthquakes we have investigated the 3 d seismic velocity and poisson s ratio structures of the bhuj source area to understand the probable cause of triggering the earthquake we used 1948 p and 1865 s wave high quality arrival times from 331 aftershocks recorded at a temporary seismic network significant variations up to 5 in velocity and 10 in poisson s ratio are revealed in the aftershock area the mainshock is located in a distinctive zone characterized by high vp low vs and high poisson s ratio in the depth range of 20 to 30 km and extending 15 to 30 km laterally this feature is very similar to that of the 1995 kobe earthquake zhao et al 1996 the anomaly may be due to a fluid filled fractured rock matrix which might have contributed to the initiation of the bhuj earthquake

combined microgravity electrical resistivity tomography and induced polarization to detect deeply buried caves algaidilla cave southern spain abstract the suitability of the combined microgravity and electrical tomography to detect and characterize caves deeply buried in limestones is tested we have selected the buried algaidilla cave in the estepa range western betic cordillera which is partially submerged below the water table and which was intersected between 26 and 66 m in depth by two boreholes at that location microgravity electrical resistivity tomography ert and induced polarization ip data was collected along four profiles algaidilla cave is associated with a 0 5 mgal residual gravity anomaly minimum microgravity models reveal an approximately horizontal n s elongated shape with a maximum length of 150 m and a width of 40 m resistivity variations provide information on the cave sectors remaining above as well as below the water table forward modeling and depth of investigation doi support the suitability of ert to constrain the cave geometry the cave is identified as having an intermediate to low resistivity feature which approximately matches the 250 m contour line along its ceiling in addition induced polarization models show high chargeability anomalies probably associated with decalcification clays the location and approximately geometry of algaidilla cave estimated from geophysical modeling suggests that nearby overburden may develop cave ins and collapse sinkholes microgravity is proved as a powerful tool to detect caves at this depth but this method alone fails to estimate the geometry ert results delineate the cavity both above and below the water table although the deepest sectors of the models should be interpreted with caution since they are less constrained by the data below the water table the cavity shows great resistivity contrast with regard to the background carbonate in addition this study points out the usefulness of the ip method for detecting decalcification clays often present at the base of karstic caves

themis observes possible cave skylights on mars 1 seven possible skylight entrances into martian caves were observed on and around the flanks of arsia mons by the mars odyssey thermal emission imaging system themis distinct from impact craters collapse pits or any other surface feature on mars these candidates appear to be deep dark holes at visible wavelengths while infrared observations show their thermal behaviors to be consistent with subsurface materials diameters range from 100 m to 225 m and derived minimum depths range between 68 m and 130 m most candidates seem directly related to pit craters and may have formed in a similar manner with overhanging ceilings that remain intact

reservoir evaluation of the lower silurian longmaxi formation shale gas in the southern sichuan basin of china abstract the lower silurian longmaxi formation the palaeozoic is organic rich black shale in the southern sichuan basin the yangtze plate of china this study analyses the lateral extent and thickness burial depth total organic carbon content and thermal maturity of the longmaxi formation black shale as the key features of the shale gas reservoir the thickness of the black shale ranges from 10 to 170 m the thickest reservoir is located in changning naxi yongchuan region the toc of the shale at the bottom of the formation 50 m thickness is above 2 0 the lateral distribution of toc varies with the lateral distribution of thickness with the maximum toc in the gongxian luzhou yongchuan region the burial depth ranges from 2000 to 4500 m the shale is thermally over mature the evaluation of reservoir characteristics indicates that the longmaxi formation has conditions appropriate for shale gas accumulation and thus resource potential in the southern sichuan basin of china the objective of this preliminary evaluation of the reservoir characteristics is to locate potential areas favourable for exploration the most favourable areas are defined here as those where the thickness of black shale is more than 100 m and the burial depth is less than 3000 m these cover approximately 12 600 km 2 the most favourable areas which cover an area of approximately 5100 km 2 are located in the northeast luzhou region