the ms 7 3 1992 suusamyr kyrgyzstan earthquake in the tien shan 2 aftershock focal mechanisms and surface deformation abstract the m s 7 3 suusamyr earthquake of 19 august 1992 was a large thrust type earthquake in the northern tien shan of kyrgyzstan an intracontinental mountain belt in central asia focal mechanisms of both the mainshock and 13 moderate sized aftershocks are consistent with a seismotectonic setting that is dominated by nnw sse horizontal compression which manifests itself in reverse faulting along roughly east west trending steeply dipping fault planes the earthquake produced surface faulting at two widely separated locations along two different fault segments the total length of which was less than 4 km detailed measurements at one of the locations indicate a net slip of at least 4 2 0 4 m a wide variety of secondary surface effects was observed in the macroseismic zone that extended over an area of 2500 km 2 the lack of extensive surface rupture from such a large event can be explained by a combination of 1 redistribution of the net slip at depth among the secondary splays that branches out from the main fault near the surface and 2 variable surface slip over the fault length the active deformation associated with this event documents a structural style that involves steeply dipping reverse faults extending from mid crustal depths to the surface at nearly uniform dip accommodating crustal shortening in the interior of the tien shan

rate of slip from multiple quaternary dating methods and paleoseismic investigations along the talas fergana fault tectonic implications for the tien shan range the 400 km long talas fergana fault is one of a series of major right lateral strike slip faults that cross the tien shan range this fault has been recognized as active in the late holocene and accommodates part of the deformation induced by the ongoing indo asian collision the kinematics and the role of this strike slip fault are poorly understood with no large earthquakes reported in the instrumental or historical catalogs and no well constrained geological slip rate estimates here we used high resolution satellite imagery to present a first detailed analysis of the fault segmentation we identified nine geometric segments based on strike variations for the talas fergana fault along the kyldau segment through morphological analyses of an offset alluvial fan and the application of multiple dating methods be 10 al 26 cl 36 luminescence and radiocarbon we calculated a late quaternary slip rate ranging from 2 2 to 6 3 mm year this rate is higher than the geodetic measurements but the discrepancy can be partly explained if the talas fergana fault accommodates shortening by counterclockwise rotation around a vertical axis paleoearthquakes identified by trenching indicate that at least two primary surface ruptures and possibly a third occurred in the past 3 800 years and that no large earthquake has ruptured the kyldau segment since at least 420 years b p possibly within the last 2 700 years making this fault segment a potential candidate to generate an earthquake with m 7 in the near future

the 2010 yushu earthquake triggered landslide hazard mapping using gis and weight of evidence modeling the yushu county qinghai province china april 14 2010 earthquake triggered thousands of landslides in a zone between 96 20 32 9 e and 97 10 8 9 e and 32 52 6 7 n and 33 19 47 9 n this study examines the use of geographic information system gis technology and bayesian statistics in creating a suitable landslide hazard zone map of good predictive power a total of 2 036 landslides were interpreted from high resolution aerial photographs and multi source satellite images pre and post earthquake and verified by selected field checking before a final landslide inventory map of the study area could be established using gis software the 2 036 landslides were randomly partitioned into two subsets a training dataset which contains 80 1 628 landslides for training the model and a testing dataset 20 408 landslides twelve earthquake triggered landslide associated controlling parameters such as elevation slope gradient slope aspect slope curvature topographic position distance from main surface ruptures peak ground acceleration distance from roads normalized difference vegetation index distance from drainages lithology and distance from all faults were obtained from variety of data sources landslide hazard indices were calculated using the weight of evidence model the landslide hazard map was compared with training data and testing data to obtain the success rate and predictive rate of the model respectively the validation results showed satisfactory agreement between the hazard map and the existing landslide distribution data the success rate is 80 607 and the predictive rate is 78 855 the resulting landslide hazard map showed five classes of landslide hazard i e very high high moderate low and very low the landslide hazard evaluation map should be useful for environmental recovery planning and reconstruction work

late cenozoic tectonic evolution of the northwestern tien shan new age estimates for the initiation of mountain building the tien shan are the quintessential intracontinental range situated more than 1000 km north of the suture between india and asia their initiation and growth in the cenozoic however remain poorly understood in this study we present stratigraphic detrital fission track and magnetostratigraphic results that provide a basis for reconstructing the cenozoic tectonic evolution of the kyrgyz range and adjacent chu basin in the northwestern tien shan detrital fission track thermochronology indicates that the northwestern tien shan was tectonically quiescent for much of the cenozoic prior to uplift and exhumation in the late miocene the kyrgyz range was buried by sediments shed from highlands to the south and or east paired bedrock fission track and u th he ages from a sampling transect of 2 4 km relief demonstrate that rapid exhumation commenced at ca 11 ma initial thrusting in the hinterland was followed by evaporite accumulation 0 4 km m y which coincided with erosion of the pre 11 ma strata that mantled the kyrgyz range between 10 and 3 ma bedrockexhumation rates decreased to 0 3 km m y while sedimentation rates decelerated initially to 0 25 km m y before accelerating to 0 4 km m y at 4 5 ma detrital fission track results indicate that by 4 5 ma

on the spatial relationship between landslides and causative factors on lantau island hong kong abstract this paper presents a statistical approach to study the spatial relationship between landslides and their causative factors at the regional level the approach is based on digital databases and incorporates such methods as statistics spatial pattern analysis and interactive mapping firstly the authors propose an object oriented conceptual model for describing a landslide event and a combined database of landslides and environmental factors is constructed by integrating the various databases within such a conceptual framework the statistical histogram spatial overlay and dynamic mapping methods are linked together to interactively evaluate the spatial pattern of the relationship between landslides and their causative factors a case study of an extreme event in 1993 on lantau island indicates that rainfall intensity and the migration of the center of the rainstorm greatly influence the occurrence of landslides on lantau island a regional difference in the relationship between landslides and topography is identified most of the landslides in the middle and western parts of the island occurred on slopes with slope angles of 25 35 while in the eastern part the corresponding range is 30 35 overlaying landslide data with land cover reveals that a large number of landslides occurred in the bareland and shrub covered area and in the transition zones between different vegetation types the proposed approach can be used not only to analyze the general characteristics of such a relationship but also to depict its spatial distribution and variation thereby providing a sound basis for regional landslide prediction

landslides in sado island of japan part ii gis based susceptibility mapping with comparisons of results from two methods and verifications abstract slope instability research and susceptibility mapping is a fundamental component of hazard management and an important basis for provision of measures aimed at decreasing the risk of living with landslides on this basis this paper presents the result of a comprehensive study on slope stability analyses and landslide susceptibility mapping carried out in part of sado island of japan various types of landslides occurred in the island throughout history little is known about the triggering factors and severity of old landslides but for many of the recent slope failures the slope characteristics and stratigraphy are such that ground surfaces retain water perennially and landslides occur when additional moisture is induced during rainfall and snowmelt a range of methods are available in literature for preparation of landslide susceptibility maps in this study we used two methods namely the analytical hierarchy process ahp and logistic regression to produce and later compare two susceptibility maps ahp is a semi qualitative method which involves a matrix based pair wise comparison of the contribution of different factors for landsliding logistic regression on the other hand promotes a multivariate statistical analysis with an objective to find the best fitting model that describes the relationship between the presence or absence of landslides dependent variable and a set of causal factors independent parameters elevation lithology and slope gradient were casual factors in this study the determinations of factor weights by ahp and logistic regression were preceded by the calculation of class weights landslide densities based on bivariate statistical analyses bsa the differences between the ahp derived susceptibility map and the logistic regression counterpart are relatively minor when broad based classifications are considered however with an increase in the number of susceptibility classes the logistic regression map gave more details but the one derived by ahp failed to do so the reason is that the majority of pixels in the ahp map have high values and an increase in the number of classes gives little change in the spatial distribution of susceptibility zones in the middle to verify the practicality of the two susceptibility maps both of them were compared with a landslide activity map containing 18 active landslide zones the outcome was that the active landslide zones do not completely fit into the very high susceptibility class of both maps for various reasons but 70 of these landslide zones fall into the high and very high susceptibility zones of the ahp map while this is 63 in the case of logistic regression this indicates that despite the skewed distribution of susceptibility indices the ahp map was better to capture the reality on the ground than the logistic regression equivalent

evidence from lake baikal for siberian glaciation during oxygen isotope substage 5d abstract the paleoclimatic record from bottom sediments of lake baikal eastern siberia reveals new evidence for an abrupt and intense glaciation during the initial part of the last interglacial period isotope substage 5d this glaciation lasted about 12 000 yr from 117 000 to 105 000 yr b p according to correlation with the specmap isotope chronology lithological and biogeochemical evidence of glaciation from lake baikal agrees with evidence for the advance of ice sheet in northwestern siberia during this time period and also with cryogenic features within the strata of kazantzevo soils in southern siberia the severe 5d glaciation in siberia was caused by dramatic cooling due to the decrease in solar insolation as predicted by the model of insolation changes for northern asia according to milankovich theory coupled with western atmospheric transport of moisture from the open areas of northern atlantic and arctic seas which became ice free due to the intense warming during preceeding isotope substage 5e other marine and continental records show evidence for cooling during 5d but not for intense glaciation late pleistocene glaciations in the northern hemisphere may have begun in northwestern siberia

quaternary tectonic evolution of the pamir tian shan convergence zone northwest china the pamir tian shan collision zone in the western tarim basin northwest china formed from rapid and ongoing convergence in response to the indo eurasian collision the arid landscape preserves suites of fluvial terraces crossing structures active since the late neogene that create fault and fold scarps recording quaternary deformation using geologic and geomorphic mapping dgps surveys of deformed terraces and osl dating we create a synthesis of the active structures that delineate the timing rate and migration of quaternary deformation during ongoing convergence new deformation rates on eight faults and folds when combined with previous studies highlight the spatial and temporal patterns of deformation within the pamir tian shan convergence zone during the quaternary terraces spanning 130 to 8 ka record deformation rates between 0 1 and 5 6 mm yr on individual structures in the westernmost tarim basin where the pamir and tian shan are already juxtaposed the fastest rates occur on actively deforming structures at the interface of the pamir tian shan orogens farther east as the separation between the pamir tian shan orogens increases the deformation has not been concentrated on a single structure but rather has been concurrently distributed across a zone of faults and folds in the kashi atushi fold and thrust belt and along the ne pamir margin where shortening rates vary on individual structures during the quaternary although numerous structures accommodate the shortening and the locus of deformation shifts during the quaternary the total shortening across the western tarim basin has remained steady and approximately matches the current geodetic rate of 6 9 mm yr

databases and gis for landslide research in europe abstract within the project the temporal occurrence and forecasting of landslides in the european community a review of the use of databases and gis for landslide research has been accomplished it shows a high potential of these techniques in storing spatial and temporal landslide data landslide inventories and in applying different modelling approaches to landslide hazard assessments at various scales there are three major strategies in european landslide research using gis and database technologies at medium and broad scales different combinations of landslide data with factor maps e g slope angle lithology and geomorphological units lead to static susceptibility and hazard assessments which allow probability evaluations for future landslide occurrences at local scales process models to simulate trajectories of paths for slope processes and deterministic slope stability models are in use in landslide frequency analysis temporal database information are correlated with recent and historical triggering factors e g precipitation and precipitation indices to calculate temporal probabilities for landslide forecasting however despite encouraging progress in applying computer technologies in european landslide research the potential of these tools is still largely untested furthermore it is clear that sophisticated technology cannot replace field work interdisciplinary research strategies and critical testing of the reliability of the model results

late quaternary slip rates across the central tien shan kyrgyzstan central asia 1 slip rates across active faults and folds show that late quaternary faulting is distributed across the central tien shan not concentrated at its margins nearly every intermontane basin contains neogene and quaternary syntectonic strata deformed by holocene north south shortening on thrust or reverse faults in a region that spans two thirds of the north south width of the central tien shan slip rates on eight faults in five basins range from 0 1 to 3 mm yr fault slip rates are derived from faulted and folded river terraces and from trenches radiocarbon optically stimulated luminescence and thermoluminescence ages limit ages of terraces and aid in their regional correlation monte carlo simulations that sample from normally distributed and discrete probability distributions for each variable in the slip rate calculations generate most likely slip rate values and 95 confidence limits faults in basins appear to merge at relatively shallow depths with crustal scale ramps that underlie mountain ranges composed of pre cenozoic rocks the sum and overall pattern of late quaternary rates of shortening are similar to current rates of north south shortening measured using global positioning system geodesy this similarity suggests that deformation is concentrated along major fault zones near range basin margins such faults separated by rigid blocks accommodate most of the shortening in the upper crust index terms 8107 tectonophysics continental neotectonics 9320 information related to geographic region asia 8010 structural geology fractures and faults

relationship of channel steepness to channel incision rate from a tilted and progressively exposed unconformity surface we examine the relationship of channel steepness to incision rate from channels eroding into a previously tilted planar and progressively exhumed unconformity surface channel and unconformity slopes are measured from a suite of channels developed on erosionally resistant paleozoic limestone exhumed by the removal of cenozoic sediments from the baybeiche range bordering the naryn basin in the western tian shan the compiled data set sampling 5 orders of magnitude of upstream drainage area 0 03 to 227 km2 is used to derive the exponent n relating channel steepness to channel incision rate and the ratio k v of the rate constant for channel incision of the resistant substrate k to the erosion rate v of the cover strata we show that for a typical value of intrinsic concavity slope area exponent 0 5 erosion rates that are proportional to specific stream power n 1 satisfy the data set however valley width data suggest that the intrinsic concavity is higher 0 8 and that incision data can also be fit if erosion is proportional to basal shear stress n 2 3 our results do not support values of n significantly greater than one using36cl exposure age dating of the unconformity surface we independently demonstrate that the cenozoic cover strata have been progressively stripped downward from the unconformity surface at a vertical rate of 1 to 2 m kyr using v 1 m kyr we constrain the rate constant k to between 6 1 and 9 2 10 4kyr 1 for incision of resistant limestone bedrock in this field setting key points channel incision relation to steepness calibrated from tilted bedrock surface chlorine 36 exposure age dating shows bedrock surface exhumed at 1 to 2 m kyr low n values consistent with shear stress n 2 3 satisfy field data 2014 american geophysical union all rights reserved

active thrust sheet deformation over multiple rupture cycles a quantitative basis for relating terrace folds to fault slip rates many recent thrust fault earthquakes have involved coseismic surface faulting and folding revealing the multifaceted nature of active thrust sheet deformation we integrate records of surface deformation subsurface structure and geochronology to investigate active surface deformation over multiple rupture cycles across the southern junggar thrust sjt in the southern junggar basin nw china fluvial terrace geometries extracted from a 1 m digital elevation model reveal records of surface faulting across a prominent fault scarp in addition terraces exhibit progressive folding across fold scarps fault and fold scarps are spatially coincident with a surface emergent sjt splay and subsurface fault bends along the sjt respectively constrained by seismic reflection data we quantify the magnitude of fault slip at depth implied by fold scarps along holocene aged terraces our method yields results consistent with independent estimates of slip implied by fault scarp relief for the same terraces four late quaternary terrace records are less continuous preserved only as fold scarps that suggest folding kinematics involving a component of limb rotation we develop a new method for quantifying fault slip at depth from terrace folds using a mechanical forward modeling approach our analysis yields quantitative relations between fold dip and fault slip allowing us to quantify sjt fault slip from terrace folds from 250 ka present sjt fault slip rate has decelerated from 7 0 mm yr in the late quaternary to 1 3 mm yr throughout the holocene these results provide new insight into the kinematics of fault bend folding for natural structures and define new methods to accurately estimate fault slip and slip rates from terrace folds in active thrust sheets

climate physiographically differentiated pan european landslide susceptibility assessment using spatial multi criteria evaluation and transnational landslide information abstract with the adoption of the eu thematic strategy for soil protection in 2006 small scale 1 1 m assessments of threats affecting soils over europe received increasing attention as landslides have been recognized as one of eight threats requiring a pan european evaluation we present an approach for landslide susceptibility evaluation at the continental scale over europe unlike previous continental and global scale landslide susceptibility studies not utilizing spatial information on the events we collected more than 102 000 landslide locations in 22 european countries these landslides are heterogeneously distributed over europe but are indispensable for the evaluation and classification of pan european datasets used as spatial predictors and the validation of the resulting assessments for the analysis we subdivided the european territory into seven different climate physiographical zones by combining morphometric and climatic data for terrain differentiation and adding a coastal zone defined as a 1 km strip inland from the coastline landslide susceptibility modeling was performed for each zone using heuristic spatial multicriteria evaluations supported by analytical hierarchy processes and validated with the inventory data using the receiver operating characteristics in contrast to purely data driven statistical modeling techniques our semi quantitative approach is capable to introduce expert knowledge into the analysis which is indispensable considering quality and resolution of the input data and incompleteness and bias in the inventory information the reliability of the resulting susceptibility map elsus 1000 version 1 1 km resolution was examined on an administrative terrain unit level in areas with landslide information and through the comparison with available national susceptibility zonations these evaluations suggest that although the elsus 1000 is capable for a correct synoptic prediction of landslide susceptibility in the majority of the area it needs further improvement in terms of data used

late cenozoic tectonic evolution of the southern chinese tian shan structural sedimentological magnetostratigraphic and 40ar 39ar thermochronological investigations were conducted in the southern chinese tian shan on the basis of our own mapping and earlier investigations in the area the late cenozoic southern tian shan thrust belt may be divided into four segments based on their style of deformation from west to east they are 1 kashi aksu imbricate thrust system 2 the baicheng kuche fold and thrust system 3 the korla right slip transfer system and 4 the lop nor thrust system the westernmost kashi aksu system is characterized by the occurrence of evenly spaced 12 15 km imbricate thrusts the baicheng kuche and korla systems are expressed by a major north dipping thrust the kuche thrust that changes its strike eastward to become a nw striking oblique thrust ramp the korla transfer zone the lop nor system in the eastern most part of the southern chinese tian shan consists of widely spaced thrusts all involved with basement rocks geologic mapping and cross section construction suggest that at least 20 40 km of crustal shortening with a horizontal shortening strain of 20 30 has occurred in the southern chinese tian shan during the late cenozoic these estimates are minimum because of both conservative extrapolation of the thrust geometries and partial coverage of the thrust belt by the cross sections the timing of initial thrusting is best constrained in the kuche basin where crustal shortening may have occurred at 21 24 ma the time of a major facies transition between lacustrine and braided fluvial sequences constrained in general by biostratigraphy and in detail by magnetostratigraphy this estimate represents only a minimum age as development of thrusts in the southern chinese tian shan may have propagated southward toward the foreland thus the sedimentary record only represents the southernmost and therefore youngest phase of thrusting if our estimate of timing for the thrust initiation 21 24 ma is correct using the estimated magnitude of shortening 20 40 km and shortening strain 20 30 the averaged rates of late cenozoic horizontal slip and shortening strain are 1 1 9 mm yr 1 and 2 9 4 5 10 16 s 1 respectively our reconnaissance 40ar 39ar thermochronological analysis in conjunction with earlier published results of apatite fission track analysis by other workers in the chinese tian shan suggests that the magnitude of cenozoic denudation is no more than 10 km most likely less than 5 km we demonstrate via a simple airy isostasy model that when the thermal effect on changes in surface elevation is negligible determination of the spatial distribution and temporal variation of both horizontal shortening strain and denudation becomes a key to reconstructing the elevation history of the tian shan using this simple model the loosely constrained magnitude of crustal shortening strain and denudation in the southern chinese tian shan implies that it may have been elevated 1 0 2 0 km since the onset of cenozoic thrusting

gis based landslide hazard predicting system and its real time test during a typhoon zhejiang province southeast china abstract yongjia county zhejiang province is located in southeast china statistics and previous reports have shown that 62 of study area has experienced various forms of slope instabilities including debris flows and landslides the geological buildup promotes the occurrence of landslides since most part of the area is covered by clayey sandstones volcanic tuffs and other types of pyroclastic rocks a gis based system is established to assess and visualize landslide hazards the information layers in the mapgis system are generated by using 11 397 regular grids with size of 5 mm 5 mm at first information matter element model is adopted to compile landslide susceptibility map by using input parameters such as lithology structural geology slope morphology and angle surface waters and human induced geomorphological changes rainfall data quantity of rainfall and rainfall intensity are obtained to calculate the effective rainfall model past landslide frequency with the combination of effective rainfall is used to determine rainfall threshold values and to generate a rainfall threshold map a warning map is compiled including five steps of warning levels by overlaying landslide hazard maps and rainfall threshold maps above the third level the population is noticed while at level five immediate evacuation takes place during yunna typhoon in august 2004 a real time warning was realized based on the landslide hazard susceptibility map and the real rainfall information the gis based system proved to be satisfactory in predicting areas of landslides marking nine critical localities during this catastrophic event

gis techniques and statistical models in evaluating landslide hazard geographical information systems gis and numerical cartography may greatly facilitate the development and use of statistical models for the assessment of regional landslide hazard from a small drainage basin located in central italy relevant geological and geomorphological factors were collected and processed by applying gis technology in particular modules were used which both generate high fidelity digital terrain models and automatically partition the terrain into main slope units the resulting information was then analysed by discriminant analysis which enabled landslide hazard and risk to be evaluated in each slope unit although not lacking drawbacks the method proved to be a feasible and cost effective approach to landslide susceptibility assessment and mapping

present day kinematics at the india asia collision zone the collision of the indian subcontinent with asia drives the growth and evolution of the greater tibetan plateau region fault slip rates resulting from the relative motion between crustal blocks can provide a kinematic description of the distribution of presentday deformation i construct a three dimensional regional scale elastic block model of the india asia collision zone that is consistent with geodetic observations of interseismic deforma tion mapped fault system geometry historical seismicity and the mechanics of the earthquake cycle this mechanical model of the elastic upper crust yields a set of kinematically consistent fault slip rates and block motions that may serve to constrain dynamic models of continental crustal dynamics

source to sink dynamics in the kyrgyz tien shan from the jurassic to the paleogene insights from sedimentological and detrital zircon u pb analyses new insights in the mesozoic geodynamic evolution and related basin range interactions in the kyrgyz tien shan were obtained based on new sedimentological and detrital zircon u pb la icp ms results from jurassic to paleogene sedimentary sequences studied sedimentary sections are located in the fergana and yarkand fergana basins to the west of the talas fergana fault tff and in the issyk kul and ming kush kokomeren basins to the east the ages of the phanerozoic zircon grains found in 18 jurassic to paleogene sandstones can be divided into four groups caledonian 470 390 ma hercynian 315 260 ma triassic 250 210 ma and jurassic 190 160 ma ages the differences in sedimentation pattern and zircon u pb results suggest that the tff played an important role in the distribution of the sedimentary deposits in the mesozoic during the early middle jurassic the tff was active and the strongest subsidence occurred in the yarkand fergana basin the provenance of its sediments can be explained both by local sources close to the tff and by more distal sources to the south west probably stretching into the present day pamir during the late jurassic early cretaceous renewed compression led to the inversion of the yarkand fergana basin around the jurassic cretaceous transition large alluvial fans developing in a semi arid to arid climate traceable around the whole tien shan were also deposited in the fergana basin a mafic sill intruded within these alluvial fans provides an emplacement age of 144 8 ma apatite u pb indicating sub volcanic activity during the early cretaceous during the late cretaceous to early paleogene the area to the west of the tff experienced marine incursions related to the proto paratethys sea the dominance of caledonian ages in the upper cretaceous lower paleogene detrital samples indicates a change in provenance whereby the drainage areas became larger towards low relief land area east of the tff

the displacement field of the landers earthquake mapped by radar interferometry geodetic data obtained by ground or space based techniques can be used to infer the distribution of slip on a fault that has ruptured in an earthquake although most geodetic techniques require a surveyed network to be in place before the earthquake1 3 satellite images when collected at regular intervals can capture co seismic displacements without advance knowledge of the earthquake s location synthetic aperture radar sar interferometry first introduced4 in 1974 for topographic mapping5 8 can also be used to detect changes in the ground surface by removing the signal from the topography9 10 here we use sar interferometry to capture the movements produced by the 1992 earthquake in landers california11 we construct an interferogram by combining topographic information with sar images obtained by the ers 1 satellite before and after the earthquake the observed changes in range from the ground surface to the satellite agree well with the slip measured in the field with the displacements measured by surveying and with the results of an elastic dislocation model as a geodetic tool the sar interferogram provides a denser spatial sampling 100 m per pixel than surveying methods1 3 and a better precision 3 cm than previous space imaging techniques12 13

the nature use and problems of historical archives for the temporal occurrence of landslides with specific reference to the south coast of britain ventnor isle of wight abstract the purpose of this paper is to describe and evaluate the nature of the european historical archives which are suitable for the assessment of the temporal occurrence and forecasting within landslides studies using the british south coast as an example the paper is based upon the british contribution to the environment programme epoch 1991 1993 a primary requirement of a research programme on process occurrence is to determine the event frequencies on as many time and space scales as possible thus the analysis of archives is potentially an essential preliminary to the study of the temporal occurrence of landslide events the range of such data sources extends from isolated fortuitously dated sites from the quaternary assemblage through inferred event impacts using dendrochronology or lichenometric time series to historical records of causal factors such as rainfall data and more recently deliberately recorded packages of cumulative or continuous data most countries have extensive historical sources which may be of considerable value in establishing the characteristics of geomorphological processes these include narrative in literature prints and other artwork terrestrial and aerial photographs remote sensing series newspapers incidental statements and scientific journals and reports these are numerous difficulties in accessing extracting organising databasing and analysing such data because they are not usually collated for scientific use problems involve such incalculable errors as the experience training and conscientiousness of the observer the editing and recording process judging the validity of the data used and the haphazard nature of recorded events in time and space despite these difficulties such data do yield a record which adds to the representative temporal sample as a level above some threshold reporting position it therefore has potential for specific statistical analysis an example of a reasonable temporal landslide record is the data base of the ventnor complex on the isle of wight initially established in 1991 by geomorphological services limited gsl now of rendel geotechnics and supplemented by the collections of the first author the record displays an increase in landslide events over the present century due probably to increasing technology and awareness of hazard and the development of process geomorphology however the landslide record was subsequently correlated with the ventnor precipitation series this indicated that wet year sequences usually gave rise to significant landslide events the increasing variability and number of rainfall events predicted by various climatic units e g the hadley centre may therefore indicate a fundamental increase in landslide events in the future

new space geodetic constraints on the distribution of deformation in central asia abstract results from repeated measurements across a 90 sites global positioning system network in central asia provide direct evidence of current high rates of tectonic deformation far north of the india eurasia suture zone the data help to quantify both the partitioning of deformation within the seismically active tien shan and northern pamirs as well as the ongoing rotation of virtually undeformed blocks such as the tarim with respect to stable eurasia the nnw to sse shortening rates derived from the computations reach values of 23 3 mm yr 1 over the ranges studied suggesting that regional deformation rates have increased considerably within the study area since the onset of cenozoic shortening 20 25 myr ago

the deep structure and reactivation of the kyrgyz tien shan modelling the past to better constrain the present abstract in the tien shan belt cenozoic to active deformation is guided by structures and rheological contrasts partly inherited from the paleozoic variscan orogeny and reactivated by the india asia collision cenozoic deformation net estimates are constrained by lithospheric scale geological cross sections which rely on reconstructions of the paleozoic central asian orogenic belt caob however several geodynamic scenarii have been proposed for its formation including a south or a north dipping subduction which are still debated due to lack of constraints here we designed numerical experiments to test different hypotheses about the initial geometry and the effective rheology of the paleo sutures and especially the one located between the tien shan and the tarim basin where most cenozoic deformation localizes the different geometries of paleozoic structures are used as input variables in the thermo mechanical models which are then run forward in time after a finite amount of shortening the structures that develop self consistently out of the proposed heterogeneities are then compared to the current cenozoic finite and active deformations we find that a crustal south dipping suture zone lying on a resistant lithospheric mantle best explains the localization of the deformation the current geometry of the structures and the moho depth variations using the model results we propose a mechanically consistent depth interpolated crustal cross section of the kyrgyz tien shan which incorporates both geological and geophysical data

re os system of black schist from the mesoproterozoic bayan obo group central inner mongolia china and its geological implications abstract the mesoproterozoic bayan obo group in central inner mongolia china represents a sedimentary sequence deposited in the bayan obo rift basin new re os dates are reported here for the black shale schist from the group re os geochronology of the black schist provides an age of 1447 42 ma which is consistent with the previous work from the literature and provides a direct and new constraint for the age of the group the dating indicates that the re os isotopes for the black schist have remained undisturbed during lower amphibolite facies metamorphism the ca 250 ma age for gold bearing sulfides also indicates that the re os isotopes for the schist have not been affected by hydrothermal overprinting of reduced fluid the initial 187 os 188 os value of 0 93 0 14 for the schist is interpreted to represent the os isotopic composition of the seawater during deposition of the group which indicates that the os composition of mesoprotozoic seawater fluctuated during the mesoproterozoic and was temporary very radiogenic similar to present day seawater the re os data suggests that rifting of the bayan obo basin peaked during ca 1447 ma and the bilute formation in the bayan obo group may have been deposited in the bayan obo sea in a restricted or semi restricted depositional environment

exhumation of basement cored uplifts example of the kyrgyz range quantified with apatite fission track thermochronology 1 the kyrgyz range the northernmost portion of the kyrgyzstan tien shan displays topographic evidence for lateral propagation of surface uplift and exhumation the highest most deeply dissected segment lies in the center of the range to the east topography and relief decrease and preserved remnants of a cretaceous regional erosion surface imply minimal amounts of bedrock exhumation the timing of exhumation of range segments defines the lateral propagation rate of the range bounding reverse fault and quantifies the time and erosion depth needed to transform a mountain range from a juvenile to a mature morphology new multicompositional apatite fission track aft data from three transects from the eastern kyrgyz range combined with published aft data demonstrate that the range has propagated over 110 km eastward over the last 7 11 myr on the basis of the thermal and topographic evolutionary history we present a model for a time varying exhumation rate driven by rock uplift and changes in erodability and the timescale of geomorphic adjustment to surface uplift easily eroded cenozoic sedimentary rocks overlying resistant basement control early rapid exhumation and exhibit slow surface uplift rates as increasing amounts of resistant basement are exposed exhumation rates decrease while surface uplift rates are sustained or increase thereby growing topography as the range becomes high enough to cause ice accumulation and to develop steep river valleys fluvial and glacial erosion becomes more powerful and exhumation rates once again increase independently determined range normal shortening rates also varied over time suggesting a feedback between erosional efficiency and shortening rate

seismic moments of major earthquakes and the rate of shortening across the tien shan three twentieth century earthquakes that richter assigned m 8 and two of comparable magnitude in the nineteenth century imply rapid deformation within the tien shan seismic moment tensors of major earthquakes in this century suggest an average shortening rate of 7 2 mm yr 1 across the tien shan in the western part however where three of the five largest earthquakes occurred the calculated rate is consistent with the value of 20 mm yr 1 measured using gps in that area by abdrakhmatov et al as avouac et al suggested the high rate in the western part apparently is a manifestation of counter clockwise rotation of the tarim basin relative to eurasia about an axis near the east end of the tien shan

the kinematic evolution of the nepalese himalaya interpreted from nd isotopes neodymium nd isotopes from the himalayan fold thrust belt and its associated foreland basin deposits are useful for distinguishing between himalayan tectonostratigraphic zones and revealing the erosional unroofing history as controlled by the kinematic development of the orogen neodymium isotopic data from the himalayan fold thrust belt in nepal n 35 reveal that the lesser himalayan zone consistently has a more negative nd 0 value than the greater and tibetan himalayan zones our data show the average nd 0 value in the lesser himalayan zone is 21 5 whereas the greater and tibetan himalayan zones have an average nd 0 value of 16 these consistently distinct values throughout nepal enable the use of nd isotopes as a technique for distinguishing between lesser himalayan zone and greater himalayan zone rock the less negative nd 0 values of the greater himalayan rocks support the idea that the greater himalayan zone is not indian basement but rather a terrane that accreted onto india during early paleozoic time neodymium isotopic data from eocene through pliocene foreland basin deposits n 34 show that sediment provenance has been dominated by greater and tibetan himalayan detritus across nepal the nd t values in the synorogenic rocks in western and central nepal generally show an up section shift toward more negative values and record the progressive unroofing of the different tectonostratigraphic zones at 10 ma in khutia khola and 11 ma in surai khola a shift in nd t values from 16 to 18 marks the erosional breaching of a large duplex in the northern part of the lesser himalayan zone this shift is not seen in eastern nepal where the nd t values remain close to 16 throughout miocene time because there has been less erosional unroofing in this region

building the northern tien shan integrated thermal structural and topographic constraints abstract paired apatite fission track and u th he dates provide the first late cenozoic cooling ages for the northern tien shan these data clearly argue for pulsed deformation since the late miocene with early 10 11 ma and late 0 3 ma intervals of rapid exhumation separated by an extended interval of much slower rates by integrating these bedrock cooling rates with shortening estimates derived from a balanced section detrital cooling ages and geomorphological estimates of conditions before deformation we reconstruct a four stage history of range growth and exhumation following 100 m yr of tectonic quiescence abruptly accelerated rock uplift exhumation and cooling in the kyrgyz range commenced at 11 ma with rates exceeding 1 km m yr during the subsequent 7 m yr deformation and cooling rates decreased three to sixfold before accelerating by comparable amounts during the past 3 m yr since mid miocene times the surface elevation of the kyrgyz range has increased 2 km consistent with

a rock magnetic record from lake baikal siberia evidence for late quaternary climate change rock magnetic measurements of sediment cores from the academician ridge region of lake baikal siberia show variations related to late quaternary climate change based upon the well dated last glacial interglacial transition variations in magnetic concentration and mineralogy are related to glacial interglacial cycles using a conceptual model interglacial intervals are characterized by low magnetic concentrations and a composition that is dominated by low coercivity minerals glacial intervals are characterized by high magnetic concentrations and increased amounts of high coercivity minerals the variation in magnetic concentration is consistent with dilution by diatom opal during the more productive interglacial periods we also infer an increased contribution of eolian sediment during the colder windier and more arid glacial conditions when extensive loess deposits were formed throughout europe and asia eolian transport is inferred to deliver increased amounts of high coercivity minerals as staining on eolian grains during the glacial intervals variations in magnetic concentration and mineralogy of lake baikal sediment correlate to the specmap marine oxygen isotope record the high degree of correlation between baikal magnetic concentration mineralogy and the specmap oxygen isotope record indicates that lake baikal sediment preserves a history of climate change in central asia for the last 250 ka this correlation provides a method of estimating the age of sediment beyond the range of the radiocarbon method future work must include providing better age control and additional climate proxy data thereby strengthening the correlation of continental and marine climate records

the ms 7 3 1992 suusamyr kyrgyzstan earthquake 1 constraints on fault geometry and source parameters based on aftershocks and body wave modeling we investigated the suusamyr kyrgyzstan earthquake of 19 august 1992 using aftershock data teleseismic body wave modeling and field observations aftershocks were recorded by the iris kyrgyzstan broadband network a temporary six station aftershock network and a regional network operated by the kyrgyz institute of seismology the aftershocks which range in depth from the surface to 18 km defined a 50 10 km long rupture zone that dips 50 13 to the south and strikes roughly east west the base of the eastern end of the aftershock zone shallowed to the east along strike and may represent a lateral ramp the surface ruptures also had an east west strike and dipped south but the total length less than 4 km was much shorter than the aftershock zone a teleseismic body wave inversion using a point source and a directivity correction yields a focal mechanism with a strike of 221 dip of 46 and a slip of 43 we obtained a moment of 4 1 1019 n m with a centroid depth between 5 and 21 km the rupture propagated along an azimuth of 330 60 which matches the relative location of the mainshock with respect to the aftershock zone the results of the aftershock study and teleseismic inversion yield a clear picture of the fault geometry of a large thrust earthquake

structural constraints in neotectonic studies of thrust faults from the magnetotelluric method kochkor basin kyrgyz republic 1 a continuous high resolution magnetotelluric mt profile 5 4 km long reveals a 1 to 2 km thick section of neogene strata thrust beneath a crystalline range front along a gently dipping decollement in the kyrgyz tien shan central asia the imaged decollement links the intrabasin akchop hills fault which currently accommodates 15 of the total shortening across the central tien shan to a crustal ramp that dips 45 beneath the range bounds from the mt data on the base of the sediments and on the dip of the crustal ramp suggest 2 5 7 5 km of total shortening across the basin margin of which at least 2 5 4 8 km clearly involves the decollement and the recently developed akchop hills fault thus a significant fraction of the total shortening across the margin has been accommodated by this young fault system combined with preliminary studies that suggest a mid miocene age for the base of the stratigraphic section results drawn from the mt section indicate that shortening rates have increased since the onset of deformation perhaps within the past 1 2 million years

synthetic aperture radar interferometry to measure earth s surface topography and its deformation synthetic aperture radar interferometry insar from earth orbiting spacecraft provides a new tool to map global topography and deformation of the earth s surface radar images taken from slightly different viewing directions allow the construction of digital elevation models of meter scale accuracy these data sets aid in the analysis and interpretation of tectonic and volcanic landscapes if the earth s surface deformed between two radar image acquisitions a map of the surface dis placement with tens of meters resolution and subcentimeter accuracy can be con structed this review gives a basic overview of insar for earth scientists and presents a selection of geologic applications that demonstrate the unique capabilities of insar for mapping the topography and deformation of the earth

low slip rates and long term preservation of geomorphic features in central asia in order to understand the dynamics of the india asia collision zone it is important to know the strain distribution in central asia whose determination relies on the slip rates for active faults1 2 3 4 5 many previous slip rate estimates of faults in central asia were based on the assumption that offset landforms are younger than the last glacial maximum 20 kyr ago 6 7 8 9 10 11 in contrast here we present surface exposure ages of 40 to 170 kyr obtained using cosmogenic nuclide dating for a series of terraces near a thrust at the northern margin of the tibetan plateau combined with the tectonic offset the ages imply a long term slip rate of only about 0 35 mm yr 1 for the active thrust an order of magnitude lower than rates obtained from the assumption that the terraces formed after the last glacial maximum our data demonstrate that the preservation potential of geomorphic features in central asia is higher than commonly assumed

major temporal variations in shortening rate absorbed along a large active fold of the southeastern tianshan piedmont china the investigation of deformation rates on a mountain piedmont can provide key information for improving our understanding of the overall dynamics of a mountain range here we estimate the shortening rate absorbed by a quaternary emergent detachment fold on the southeastern piedmont of the tianshan china our work is primarily based on new 10be cosmogenic exposure dating of deformed alluvial surfaces the method we have developed combines depth profiling with sampling of surface cobbles thereby allowing exposure time erosion rate and inheritance to be simultaneously constrained the exposure ages of the uppermost uplifted alluvial surfaces are around 140 17 ka140 17 ka 130 9 ka130 9 ka and 47 9 ka47 9 ka from west to east a terrace lying below the 140 ka surface is dated at 65 5 ka65 5 ka the ages of the uplifted and folded alluvial surfaces were then combined with estimates of shortening obtained using two distinct methods 1 the excess area method where sedimentation rates extracted from magnetostratigraphic studies are used to determine the amount of sedimentation after the abandonment of the river and 2 a folding model derived from sandbox experiments the late pleistocene shortening rates are shown to be between 0 4 0 1 mm yr0 4 0 1 mm yr and 0 8 0 5 mm yr0 8 0 5 mm yr on the western part of the fold and 2 1 0 4 mm yr2 1 0 4 mm yr along its central part the central part of the frontal yakeng anticline therefore accommodates up to 25 of the total shortening currently absorbed across the whole eastern tianshan range 8 mm yr however this situation seems to have prevailed for only the last 150 ka as the shortening rate absorbed by this nascent fold was previously ten times slower while the initiation of folding of the yakeng anticline can be traced back to 5 5 ma ago the basinward migration of the active deformation front onto the yakeng fold is a relatively recent phenomenon and appears to be diachronous from west to east probably in relation to the tectonic activity of the folds in the hinterland

a multi method approach to study the stability of natural slopes and landslide susceptibility mapping abstract in this paper a multi method approach for the assessment of the stability of natural slopes and landslide hazard mapping applied to the dakar coastal region is presented this approach is based on the effective combination of geotechnical field and laboratory works of gis and of mechanical deterministic and numerical stability analysis by using this approach valuable results were gained regarding instability factors landslide kinematics simulation of slope failure and coastal erosion this led to a thorough assessment and strong reduction in the subjectivity of the slope stability and hazard assessment and to the development of an objective landslide danger map of the sw coast of dakar analysis of the results shows that the slides were influenced by the geotechnical properties of the soil the weathering the hydrogeological situation and the erosion by waves the landslide susceptibility assessment based on this methodological approach has allowed for an appropriate and adequate consideration of the multiple factors affecting the stability and the optimization of planning and investment for land development in the city

late oligocene early miocene initiation of shortening in the southwestern chinese tian shan implications for neogene shortening rate variations abstract the cenozoic tian shan is one of the preeminent examples of an intracontinental orogen however there remains a significant controversy over when deformation related to the india asia collision commenced and therefore how shortening within the mountains has been partitioned over time one approach has been to look at the modern shortening rate as measured by geodetic studies combined with estimates of the total shortening across the range and extrapolate backwards this approach suggests that the onset of range construction was ca 10 ma k y abdrakhmatov s a aldazhanov b h hager m w hamburger t a herring k b kalabaev k b kalabayev v i makarov p molnar s v panasyuk m t prilepin r e reilinger i s sadybakasov b j souter y a trapeznikov v y tsurkov a v zubovich relatively recent construction of the tien shan inferred from gps measurements of present day crustal deformation rates nature 384 6608 1996 450 453 an alternate method is to determine the age of the onset of exhumation using thermochronology we present 19 new apatite fission track aft results from the southwestern chinese portion of the belt this region represents the first area exhumed during the late tertiary along a transect at ca 76 e exhumation commenced at the oligocene miocene boundary 24 ma along the maidan and muziduke thrusts which bound the southern side of the kokshaal range subsequently deformation propagated ca 20 km south to the kashi basin bounding thrust kbt which was exhumed by no earlier than 18 9 3 3 ma three detrital aft samples from plio pleistocene strata deposited ca 20 km farther south contain fission track grain age peaks that young monotonically upwards from 20 9 7 0 5 3 ma to 15 9 5 4 4 0 ma with a fairly constant lag time of 16 to 18 ma these ages combined with structural data suggest that both the hanging wall and the footwall of the kbt experienced a renewed episode of exhumation during the latest cenozoic the discrepancy between the late oligocene miocene initiation of significant exhumation shown herein and the 10 ma initiation estimate from geodesy suggests that the tian shan has undergone a complex late cenozoic shortening history assuming that the present shortening rate could account for the total amount of cenozoic shortening in 10 ma and realizing that shortening initiated at least 15 myr earlier we conclude that the shortening rate must have varied over time possibly in pulsed southward migrating events and that the present rate may not reflect the average rate since initiation of range uplift

combining multiple change detection indices for mapping landslides triggered by typhoons an important part of landslide research is the interpretation and delineation of landslides which has increasingly been based on high resolution satellite images in recent years using pre and post event formosat 2 satellite images as the data sources this study presents a new method that combines four change detection techniques for mapping shallow landslides triggered by typhoons in taiwan the four techniques are normalized differential vegetation index ndvi spectral angle principal component analysis and independent component analysis we applied the multiple change detection mcd technique to map landslides triggered by typhoons comparisons were then made between mcd results with landslide inventory maps compiled by using a single index ndvi comparison results show that mcd can perform better than a single index in dealing with old landslides and landslides with non homogeneous spectral responses mcd is also able to detect small landslides which are often missed by visual analysis additionally landslide maps prepared by mcd include runout features of sediment deposits from debris flows a relatively fast processing chain mcd is expected to become a useful new tool for emergency management after a typhoon event which occurs on average four to five times a year in taiwan

large ancient earthquakes in the western issyk kul basin kyrgyzstan northern tien shan abstract new paleoseismological and archaeoseismological data from the western issyk kul basin of kyrgyzstan northern tien shan provide new insights on active fault in the actively deforming basement involved thrust system of central asia newly discovered fault scarps follow south and north dipping thrust faults which delineate the kyrgyz and kungey ranges bordering the issyk kul basin motion on these faults generated earthquakes with magnitudes 6 2 7 6 and msk 64 shaking intensities viii xi deformation observed in the zone of the toguz bulak fault results from two holocene earthquakes and another event that occurred about 8000 yr bp two more events at 13 000 and 3000 yr bp deformed the northeastern periphery of the kyzyl ompul uplift archaeoseismological research in the northern sary bulun settlement in the western periphery of the boz barmak uplift revealed traces of another earthquake of msk 64 shaking intensity i viii dating back to the 12th century the obtained data correlates well with results of previous paleoseismological and archeoseismological studies they show that in the northern tien shan there were clusters of strong earthquakes with ages of 14 13 8 4 3 ka ago and in the 11 12th centuries ad divided by periods of 4 5 ka we infer that coseismic slip on these faults may have formed a tectonic dam at the edge of the basin through growth of the boz barmak uplift and this dam ultimately deflected the chu river into its modern channel which bypasses the lake lacustrine sediments in the northeastern periclinal segment of the boz barmak uplift bear signatures of soft sediment deformation structures seismites corresponding to seven m 5 5 5 i vi vii earthquakes timed at about 20 000 yr bp

from decades to epochs spanning the gap between geodesy and structural geology of active mountain belts geodetic data from the global navigation satellite system gnss and from satellite interferometric radar insar are revolutionizing how we look at instantaneous tectonic deformation but the significance for long term finite strain in orogenic belts is less clear we review two different ways of analyzing geodetic data velocity gradient fields from which one can extract strain dilatation and rotation rate and elastic block modeling which assumes that deformation is not continuous but occurs primarily on networks of interconnected faults separating quasi rigid blocks these methods are complementary velocity gradients are purely kinematic and yield information about regional deformation the calculation does not take into account either faults or rigid blocks but where gnss data are dense enough active fault zones and stable blocks emerge naturally in the solution block modeling integrates known structural geometry with idealized earthquake cycle models to predict slip rates on active faults future technological advances should overcome many of today s uncertainties and provide rich new data to mine by providing denser more uniform and temporally continuous observations

a creeping intracontinental thrust fault past and present slip rates on the northern edge of the tien shan kazakhstan we demonstrate that a continental interior reverse fault is deforming by aseismic creep presently and likely also in the long term the karkara rangefront fault part of the larger main terskey front forms the northern boundary of the high terskey tien shan in southeastern kazakhstan and is a mature structure with evidence for high slip rates throughout the late cenozoic combining field studies with a satellite stereo image derived digital elevation model 2 m resolution we map a series of fluvial terraces along the rangefront which are uplifted by up to 300 m above the present river level radiocarbon ages from one catchment constrain the ages of the lowermost two terraces to be 4 5 ka and 10 15 ka consistent with prominent regionally extensive terraces observed elsewhere in the tien shan based on conservative estimates for the fault dip under the displaced terraces we estimate a slip rate along the fault plane of 3 5 1 7 0 4 mm yr 1 on the karkara rangefront fault and a further 0 8 mm yr 1 on a fold structure in the kegen basin that we infer is driven by a detachment from the main rangefront we therefore estimate a minimum shortening rate across the rangefront of 1 1 3 3 mm yr 1 elastic modelling of the regional gps velocity field suggests that the fault is presently creeping at 3 mm yr 1 horizontal shortening consistent with the upper limit of our late quaternary slip rate estimate this is the fastest known slip rate in the northern tien shan and the only individual structure resolved in the regional velocity field at present the fault is accumulating minimal strain and there is evidence in the geomorphology that this creep is sustained in the long term but whether or not it is also capable of generating earthquakes requires further study

gps velocity field for the tien shan and surrounding regions 1 measurements at 400 campaign style gps points and another 14 continuously recording stations in central asia define variations in their velocities both along and across the kyrgyz and neighboring parts of tien shan they show that at the longitude of kyrgyzstan the tarim basin converges with eurasia at 20 2 mm yr nearly two thirds of the total convergence rate between india and eurasia at this longitude this high rate suggests that the tien shan has grown into a major mountain range only late in the evolution of the india eurasia collision most of the convergence between tarim and eurasia within the upper crust of the tien shan presumably occurs by slip on faults on the edges of and within the belt but 1 3 mm yr of convergence is absorbed farther north at the dzungarian alatau and at a lower rate with the kazakh platform to the west the tarim basin is thrust beneath the tien shan at 4 7 mm yr with respect to eurasia the ferghana valley rotates counterclockwise at 0 7 myr 1 about an axis at the southwest end of the valley thus gps data place a bound of 4 mm yr on the rate of crustal shortening across the chatkal and neighboring ranges on the northwest margin of the ferghana valley and they limit the present day slip rate on the right lateral talas ferghana fault to less than 2 mm yr gps measurements corroborate geologic evidence indicating that the northern margin of the pamir overthrusts the alay valley and require a rate of at least 10 and possibly 15 mm yr

fluvial response to large rock slope failures examples from the himalayas the tien shan and the southern alps in new zealand we describe remnants of large 10 7 10 10 m 3 late pleistocene to holocene rockslides and rock avalanches that block ed rivers and are preserved in the himalayas the tien shan and the new zealand southern alps despite rates of uplift and erosion of up to 10 mm year 1 these natural dams control fluvial response on 10 1 10 4 year timescales by a storing and releasing sediment during forced alluviation and fluvial re incision b relocating river channels through diversion or seepage c inhibiting river erosion into bedrock d formingpersistentlong profileknickpointsandknickslopesassociatedwithsteephigh energy n10 3 wm 2 breachand epigenetic bypass gorges and fluvial hanging valleys and e shaping valley floor morphology sediments indicate that rockslidedammed lakes may persist up to 10 4 years before being drained or infilled several short lived 10 0 10 2 year historical rockslide dams in the indian and nepal himalayas and the southern alps have had marked volumetric impacts on catchment sediment budgets shortly following failure therefore we caution against the linear extrapolation of sediment delivery from prehistoric rockslide dams through time as a response variable we find reach scale changes to channel gradient to be prominent and persistent indicators of fluvial response to large rock slope failures 2006 elsevier b v all rights reserved

transient landscape evolution of basement cored uplifts example of the kyrgyz range tian shan 1 the kyrgyz range located on the northern margin of the western tian shan illustrates long term 106 107 year transient landscape evolution in response to an active basement cored rock uplift eastward propagation of range uplift has progressively exposed resistant bedrock capped by a tilted formerly planar pre cenozoic unconformity we develop an approximate stream power based analytic model of transient river profile incision into progressively exposed and resistant bedrock to explore the patterns of channel development into the unconformity surface this analysis shows that the unconformity can be preserved as a geomorphic marker defined by upland headwaters and interfluvial areas though channels are not at equilibrium with rock uplift prominent knickpoints are not predicted to develop on main stem channels however knickpoints are predicted to develop on tributaries upstream of their junctions with the trunk stream because of differential erosion rates initial channel slope and transient channel form are both sensitive to the n value of the stream power model and could prove useful for calibration of n from field data accumulation of catchment area a proxy for discharge into larger catchments develops a positive feedback where larger drainages with higher stream power at a given slope undermine and capture adjacent drainage area a simple model of competitive fluvial incision illustrates the role of tributary junction position in maximizing stream power expended upon the trunk stream examples from the kyrgyz range illustrate the effects of tributary junction position on fluvial relief and we propose that adjustments to the tributary network through stream capture are ongoing within this landscape even after several kilometers of exhumation

pliocene pleistocene initiation style and sequencing of deformation in the central tien shan in response to the indo asian collision deformation of the tien shan initiated at 25 ma along the northwestern margin of the tarim basin 300 km north the kyrgyz range began deforming 15 ma later although multiple intervening structures across the tien shan are currently active the sequencing of initial deformation across the orogen s entire width remains poorly known to determine whether deformation migrated sequentially northward or developed less predictably we documented deformation patterns within the naryn basin in south central kyrgyzstan detailed mapping and a published balanced cross section across the naryn basin suggest that deep seated relatively steeply dipping thrust faults have disrupted the basin during late cenozoic deformation dating of deformed fluvial terraces with ages between 10 and 250 ka constrains the rate of deformation across relatively young structures in the tien shan interior based on geodetic surveys of dated terraces local rates of relative rock uplift span from 0 3 to 3 5 mm yr folding rates and patterns are temporally persistent at a given site moreover they mimic modern geodetic rates measured from interferometric synthetic aperture radar extrapolating these rates into the past suggests that structures within the interior of the naryn basin formed in the last 1 myr whereas the ranges surrounding the basin initiated at least 1 4 myr earlier hence within the naryn basin itself deformation has migrated from margins to interior similarly these new chronologies indicate that at least some deformation in the interior of the tien shan initiated millions of years later than along either orogenic margin 2014 american geophysical union all rights reserved

mechanisms of active folding of the landscape southern tian shan china 1 we explore the kinematic mechanisms of active large scale folding based on analysis of two adjacent major anticlines in tian shan central asia that share an acceleration of shortening rate leading to topographic emergence and folded geomorphic surfaces their folding mechanisms are fundamentally different yakeng anticline is a gentle pure shear detachment fold with 1200 m of shortening and a well constrained history of growth beginning at 5 5 ma with an order of magnitude increase in shortening rate from 0 16 to 1 2 1 6 mm yr at 0 16 0 21 ma the shape of the deformed topographic surface and of subsurface horizons deposited during deformation is a linearly proportional image at reduced amplitude of the deeper structure which shows that instantaneous uplift rates have been pointwise linearly proportional to the current finite fold amplitude in contrast quilitak anticline is a complex fault bend fold with uplift rates proportional to the sine of the fault dip showing discontinuities in uplift rate across active axial surfaces the 10 to 20 km wide anticline is topographically emergent only in a central 5 to 7 km wide mountainous uplift the abrupt southern edge of which is marked by 600 to 700 m high triangular facets that result from active folding of a pediment across an active axial surface the giant facets are shown to form by kink band migration and record postemergence deformation since an order of magnitude acceleration in shortening rate from 0 6 to 4 5 mm yr apparently contemporaneous with yakeng sections logged across the active 115 m wide hinge zone show that recent strata provide a bed by bed record of fold scarp growth which is quantitatively deciphered by fitting bed shapes to a finite width kink band migration model

a growing structure near the deformation front in sw taiwan as deduced from sar interferometry and geodetic observation 1 we apply the d insar technique to monitor the active growing structure on the tainan tableland near the deformation front in sw taiwan using ers sar images in the period of 1996 2000 interferometric processing of six sar images reveals the average slant range displacement srd to be 12 5 mm yr and it increases from the west edge of the tainan tableland and decreases across the houchiali fault the gps campaign data indicate an average horizontal movement of 12 4 mm yr in the direction of n44 w for the tainan tableland with respect to the western coastline five precise leveling surveys across the tainan tableland over two years show an uplift rate of 14 mm yr for the benchmarks on the tableland by combining the horizontal velocity of gps data and the srd of d insar we transfer the srd into vertical deformation and discuss the deformation pattern and seismic hazards in the tainan area

dip range for intracontinental reverse fault ruptures truth not stranger than friction abstract histograms of fault dips have been compiled for moderate to large m 5 5 reverse slip intracontinental earthquakes with the slip vector raking 90 30 in the fault plane the principal data set is restricted to earthquakes where the fault plane in the focal mechanism can be unambiguously distinguished from the auxilliary plane the reverse fault dips are bracketed within the range 12 1 the observed dip range is consistent with reactivation of faults possessing rock friction coefficients within byerlee9s 1978 range 0 85 s 0 6 undergoing frictional lockup at dips approaching 60 the broad 25 to 35 peak may arise from progressive domino steepening of imbricate reverse faults above the optimal dip for reactivation in regions undergoing bulk shortening paucity of very low angle thrusts implies that it is generally the steeper ramps within ramp flat assemblages that fail in moderate to large earthquakes the subsidiary peak at 45 to 55 likely results from compressional reactivation of former normal faults in areas undergoing tectonic inversion requiring some degree of fluid overpressuring the results are consistent with previous studies on the dip range for active normal faults that again demonstrate frictional lockup at reactivation angles approaching 60 together these analyses suggest that byerlee friction coefficients apply to faults with displacements of up to a few kilometers

late pleistocene shortening rate on the northern margin of the yanqi basin southeastern tian shan nw china abstract how strain is distributed and partitioned on individual faults and folds on the margins of intermontane basins remains poorly understood the haermodun ha anticline located along the northern margin of the intermontane yanqi basin on the southeastern flank of the tian shan preserves flights of passively deformed alluvial terraces these terraces cross the active anticline and can be used to constrain local crustal shortening and uplift rates geologic and geomorphic mapping in conjunction with high resolution dgps topographic surveys reveal that the terrace surfaces are perpendicular to the fold s strike and display increased rotation with age implying that the anticline has grown by progressive limb rotation combined with the open sinusoidal curve model and excess area method we calculated uplift and shortening values for each terrace since abandonment using the published exposure ages of each terrace we found the vertical uplift rate gradually decreased from 0 43 to 0 11 mm a whereas the shortening rate remained constant at 0 3 mm a since the anticline began to grow a fresh fault scarp 0 4 0 1 m high is visible along the southern portion of the ha anticline and is interpreted to be the most recent evidence of seismic activity using an estimated rupture area and the length of the fresh offset created by this earthquake we estimate that the main thrust underlying the ha anticline has generated moderate m

an overview of scale pattern process relationships in geomorphology a remote sensing and gis perspective abstract satellite remote sensing and geographic information systems are emerging technologies in geomorphology they offer the opportunity to gain fresh insights into biophysical systems through the spatial temporal spectral and radiometric resolutions of remote sensing systems and through the analytical and data integration capability of gis the two technologies can be linked together into a synergistic system that is particularly well suited to the examination of landscape conditions through the interrelationships of scale pattern and process a paradigm that has gained prominence in the fields of biogeography and landscape ecology in this study we apply optical and microwave remote sensing systems and gis methodologies to case studies framed within the fluvial and alpine environments we use the scale pattern and process paradigm to explore landscape relationships in those environments satellite image processing change detection analyses digital elevation models gis derived geomorphic indices and variables composition and pattern metrics of landscape organization and scale dependent analyses are described and related to the study of river channel abandonment and the alpine treeline ecotone we describe appropriate remote sensing and gis techniques for geomorphic research and demonstrate the use of such techniques in the application of the scale pattern and processes perspective in geomorphic studies

evaluating triggering and causative factors of landslides in lawnon river basin taiwan this study evaluates triggering and causative factors of landslides by comparing their occurrence in the lawnon river basin prior to and after rainfall and earthquake events over a five year period 2005 2009 the landslide ratio in the study area was low less than 4 before 2007 and significantly increased in the wake of typhoon morakot in 2009 the high accumulation of rainfall was the major triggering factor in addition the major seismic activity of march 4 2008 also contributed to landslide occurrence the combined influence of rainfall and the earthquake is evaluated based on multi variable regression analysis though no significant co seismic landslides were found after the march 4 2008 earthquake its influence on slope stability has been observed from the apparent growth of landslide ratio in the four rainfall events following the quake causative factors include the higher landslide ratios occurring in sedimentary rock zones especially sandstone formations with intercalations of shale and dip slopes which are demonstrably prone to plane failures

three dimensional velocity structure and earthquake locations beneath the northern tien shan of kyrgyzstan central asia we used the arrival times of local earthquakes and quarry blasts recorded by the kyrgyzstan broadband network knet to obtain three dimensional 3 d p and s wave velocity models of the upper crust beneath an actively deforming mountain front and its associated foreland in the kyrgyz tien shan the continuous velocity models described by cubic b spline interpolation of the squared slowness over a regular 3 d grid were computed by simultaneous inversion of hypocenter and medium parameters exact ray tracing was done in the smooth 3 d medium by shooting rays from the sources to the stations by an analytical perturbation method based on the paraxial ray theory the deduced large sparse linear system was solved using the damped iterative least squares algorithm lsqr the stability and resolution of the result was qualitatively tested by two synthetic tests the spike test and the checkerboard resolution test we found that the models are well resolved up to a depth of 27 km for most parts of our image domain the p and s wave velocity models are consistent with each other and provide evidence for marked heterogeneity in the upper crustal structure beneath the northern tien shan at shallower depths 7 km the sediment filled foreland is imaged as a relatively lower velocity feature compared to the mountains which are cored by crystalline basement rocks in contrast at midcrustal depths the mountains are underlain by relatively lower velocity materials compared to the foreland a distinct contrast in velocity structure is also observed between the eastern and western parts of the kyrgyz range at midcrustal depths with the presence of relatively higher velocities toward the east the seismicity is concentrated near the traces of major active faults and extends deeper beneath the foreland compared to the mountains the regional compression in the tien shan is accommodated along a series of high angle reverse faults distributed throughout the orogenic system that extend from the surface down to midcrustal depths the range bounding fault zone can be identified by a sharp lateral gradient in seismic velocities with a pronounced southward dip combined with a zone of seismicity that also deepens to the south and reverse fault source mechanisms from moderate sized events a pronounced low velocity zone lvz is imaged in the p wave field at midcrustal depths beneath the western part of the kyrgyz range this lvz is presumably correlatable with reported high conductivity zones in this region that have been proposed to mark active fault zones along which fluid migration occurs the location of the lvz which is closely coincident with the depth of maximum earthquake generation might imply that it is a crustal decoupling zone at the brittle ductile transition

thermochronologic insight into late cenozoic deformation in the basement cored terskey range kyrgyz tien shan 1 basement cored ranges formed by reverse faulting within intracontinental mountain belts are often composed of poly deformed lithologies geological data capable of constraining the timing magnitude and distribution of the most recent deformational phase are usually missing in such ranges in this paper we present new low temperature thermochronological and geological data from a transect through the basement cored terskey range located in the kyrgyz tien shan using these data we are able to investigate the range s late cenozoic deformation for the first time displacements on reactivated faults are constrained and deformation of thermochronologically derived structural markers is assessed these structural markers postdate the earlier deformational phases providing the only record of cenozoic deformation and of the reactivation of structures within the terskey range overall these structural markers have a southern inclination interpreted to reflect the decreasing inclination of the reverse fault bounding the terskey range our thermochronological data are also used to investigate spatial and temporal variations in the exhumation of the terskey range identifying a three stage cenozoic exhumation history 1 virtually no exhumation in the paleogene 2 increase to slightly higher exhumation rates at 26 20 ma and 3 significant increase in exhumation starting at 10 ma

the landslide database for germany closing the gap at national level abstract the federal republic of germany has long been among the few european countries that lack a national landslide database systematic collection and inventory of landslide data still has a long research history in germany but one focussed on the development of databases with local or regional coverage this has changed in recent years with the launch of a database initiative aimed at closing the data gap existing at national level the present paper reports on this project that is based on a landslide database which evolved over the last 15 years to a database covering large parts of germany a strategy of systematic retrieval extraction and fusion of landslide data is at the heart of the methodology providing the basis for a database with a broad potential of application the database offers a data pool of more than 4 200 landslide data sets with over 13 000 single data files and dates back to the 12th century all types of landslides are covered by the database which stores not only core attributes but also various complementary data including data on landslide causes impacts and mitigation the current database migration to postgresql postgis is focused on unlocking the full scientific potential of the database while enabling data sharing and knowledge transfer via a web gis platform in this paper the goals and the research strategy of the database project are highlighted at first with a summary of best practices in database development providing perspective next the focus is on key aspects of the methodology which is followed by the results of three case studies in the german central uplands the case study results exemplify database application in the analysis of landslide frequency and causes impact statistics and landslide susceptibility modeling using the example of these case studies strengths and weaknesses of the database are discussed in detail the paper concludes with a summary of the database project with regard to previous achievements and the strategic roadmap

insar observations of low slip rates on the major faults of western tibet two contrasting views of the active deformation of asia dominate the debate about how continents deform i the deformation is primarily localized on major faults separating crustal blocks or ii deformation is distributed throughout the continental lithosphere in the first model western tibet is being extruded eastward between the major faults bounding the region surface displacement measurements across the western tibetan plateau using satellite radar interferometry insar indicate that slip rates on the karakoram and altyn tagh faults are lower than would be expected for the extrusion model and suggest a significant amount of internal deformation in tibet

relatively recent construction of the tien shan inferred from gps measurements of present day crustal deformation rates the tien shan a high seismically active intracontinental mountain belt 1 000 2 000 km north of the himalaya has grown as a result of india s collision with asia1 the crustal shortening 200 50 km refs 2 3 and thickening that gave rise to the tien shan accommodates only a small fraction of india s total penetration into asia 2 000 3 000km and the temporal relationship of deformation in this belt to the india asia collision remains unclear here we report geodetic measurements of the tien shan using the global positioning system gps that indicate that the current crustal shortening rate is nearly half of india s convergence rate with eurasia in this area4 we infer a total shortening rate for the tien shan of 20 mm yr 1 which is approximately twice that inferred previously from the extrapolation of slip rates in the holocene3 and earthquake induced displacements during this century5 suggesting that the rate of mountain building in this region has accelerated several fold since the onset of collision 50 55 myr ago6 7 if as we argue the current shortening rate can be extrapolated to geological timescales then our results suggest that most of the tien shan has been constructed during the past 10 myr perhaps in response to an increased horizontal force following an abrupt rise of the tibetan plateau8 9

basin width control of faulting in the naryn basin south central kyrgyzstan 1 in central asia s tien shan deformation is distributed across the wide orogen a characteristic of intracontinental mountain building active faults are commonly found within intramontane basins that separate its constituent ranges in order to explore the controls on this intramontane basin deformation we study the naryn basin of south central kyrgyzstan a series of five balanced cross sections reveals a transition in patterns of faulting from faults confined to basin margins to faults focused within the basin center the 20 km wide eastern naryn basin displays deformation attributed to low angle splays of the northern basin bounding fault in the 40 km wide western naryn basin the pattern of deformation linked to the northern range remains but is accompanied by steeper faults that dip both south and north without being directly linked to the basin bounding fault we compare these cross sections to synthetic aperture radar interferometry insar measurements of surface deformation profiles of insar derived surface deformation rates across the naryn basin reveal that in the west deformation is distributed across the broad basin interior whereas in the east rapid uplift is concentrated at the margin of the narrower basin from the geodetic and structural data we infer that in the western naryn basin deformation has migrated away from the northern basin margin and into the interior deformation of the eastern basin interior however remains linked to the basin bounding fault a simple mechanical model demonstrates that basin width may control basin deformation whereby basin interior faulting in the narrow eastern naryn basin is inhibited by the overburden of adjacent ranges citation goode j k d w burbank and b bookhagen 2011 basin width control of faulting in the naryn basin south central kyrgyzstan tectonics 30 tc6009 doi 10 1029 2011tc002910

optical dating of sediments a new method for dating sediments is proposed which determines the time since the sediment was last exposed to sunlight an argon ion laser is used to excite electrons from thermally stable light sensitive traps and the subsequent luminescence used as a measure of the past radiation dose two sample sequences spanning the periods 0 700 kyr and 0 6 kyr show steadily increasing luminescence with age an age of 62 8 kyr is obtained for a silt radiocarbon dated at 58 8 0 3 kyr problems were found with two much younger samples

coseismic fold scarps and their kinematic behavior in the 1999 chi chi earthquake taiwan 1 discrete scarps that are created or reactivated during large earthquakes are a locus of concentrated hazard a number of the coseismic scarps activated in the 1999 chi chi earthquake are actually fold scarps which display several types of ground deformation characterized by localized folding and are distinct from classic fault scarps which form by a fault cutting the surface this paper documents and analyzes fold scarps that formed or reactivated in the 1999 chi chi taiwan earthquake our results show the chi chi fold scarps can be generally divided into two types 1 those associated with folding ahead of the tip of a blind thrust fault at shallow depths and 2 those associated with folding by kink band migration above fault bends at substantial depths ranging from 0 8 to 5 km the previously published trishear model can be applied to model the former type while a new curved hinge kink band migration model is provided to describe the behavior of the latter type a key feature of fold scarps of the second type is that hinge zones are typically wide 25 100 m relative to the displacement in a single earthquake 1 10 m which exerts a significant control on fold scarp morphology and evolution because the coseismic strains of both types of fold scarps display relatively wide deformation zones 10 100 m relative to fault scarps wider set back zones might be appropriate from a public policy point of view to alleviate the risk to structural damage and collapse resulting from permanent ground deformation