magnitude scale and quantification of earthquakes despite various shortcomings the earthquake magnitude scale is one of the most fundamental earthquake source parameters to be used for catalogs although use of a uniform scale is desirable it is not always possible because of changes in instrumentation the data reduction method and the magnitude formula the station distribution etc as a result various magnitude scales have been developed and are currently in use recent developments in seismometry and earthquake source theories provide more quantitative source parameters than the magnitude in order to maintain continuity and uniformity of the data it is important to relate these magnitude scales and the new parameters in view of this importance relations between different magnitude scales are examined with an emphasis on the difference in the period of the waves used for the magnitude determination use of several magnitude scales determined at different periods provides a convenient method for characterizing earthquakes the moment magnitude can be used to quantify both shallow and deep earthquakes on the basis of wave energy radiated and provides a uniform scheme

shallow creep on the haiyuan fault gansu china revealed by sar interferometry interferometric synthetic aperture radar data are used to map the interseismic velocity field along the haiyuan fault system hfs at the north eastern boundary of the tibetan plateau two m 8 earthquakes ruptured the hfs in 1920 and 1927 but its 260 km long central section known as the tianzhu seismic gap remains unbroken since 1000 years the envisat sar data spanning the 2003 2009 period cover about 200 300 km2 along three descending and two ascending tracks interferograms are processed using an adapted version of roi pac the signal due to stratified atmospheric phase delay is empirically corrected together with orbital residuals mean line of sight velocity maps are computed using a constrained time series analysis after selection of interferograms with low atmospheric noise these maps show a dominant left lateral motion across the hfs and reveal a narrow 35 km long zone of high velocity gradient across the fault in between the tianzhu gap and the 1920 rupture we model the observed velocity field using a discretized fault creeping at shallow depth and a least squares inversion the inferred shallow slip rate distribution reveals aseismic slip in between two fully locked segments the average creep rate is 5 mm yr 1 comparable in magnitude with the estimated loading rate at depth suggesting no strain accumulation on this segment the modeled creep rate locally exceeds the long term rate reaching 8 mm yr 1 suggesting transient creep episodes the present study emphasizes the need for continuous monitoring of the surface velocity in the vicinity of major seismic gaps in terms of seismic hazard assessment

littoral landforms and pedosedimentary sequences indicating late holocene lake level changes in northern central europe a case study from northeastern germany abstract a multidisciplinary study was carried out at lake groser furstenseer see lfs in order to explore the potential of littoral sediments palaeosols and landforms as indicators of historical lake level changes this research was initiated to investigate the extent to which lakes in northern central europe responded hydrologically to climatic and land use changes in the last millennium specific landforms investigated comprise lake terraces beach ridges local basins peatlands and dunes revealing a wealth of sedimentary sub environments at the lakeshore eleven sections were recorded with subsequent sedimentological pedological geochronological osl 14c and palaeobotanical pollen macro remains analyses most of the pedosedimentary littoral sequences show a succession of basal glacial sand intermediate palaeosols and lacustrine sand on top a broader number of semi terrestrial buried palaeosols along the lakeshore were systematically identified and analysed providing evidence for changing hydrological conditions during the late holocene additional historical data from the last centuries e g maps aerial photos public records allow the lake levels reconstructed from geoarchives to be connected with modern gauging data all local data sources available enable a tracing of lake level changes of the lfs during the last millennium comprising periods of relatively low c 1200 ad 2000s ad and relatively high water levels c 1250 1450 ad c 1780 ad 1980s ad the amplitude of lake level changes during the last c 1000 years amounts to c 3 m so that the fluctuations of the last 30 years recorded by lake level monitoring only reflect a small amount of the potential variability regional climate and local land use history suggest that the medieval lake level dynamics of lfs were primarily governed by climate and secondarily influenced by human impact on the drainage system at present the lake level is additionally influenced by the impact of highly water consuming pine plantations in the catchment area the regional significance of the local development at lfs can be demonstrated by comparison with other regional and supra regional lake level data the present study underlines the potential of a closer examination of the littoral zone for lake level reconstructions with high altitudinal precision

contemporary crustal deformation in east asia constrained by global positioning system measurements global positioning system gps measurements collected since the early 90 s allow us to derive geodetic velocities at 16 permanent stations in east asia and 68 campaign mode sites in north china the resulting velocity field shows the following 1 contrary to the early inferences that the shanxi rift has accommodated significant right slip motion our results suggest that the rift system at least in its northern part in north china is under ese wnw extension at a rate of 4 2 mm yr the velocity field also suggests that an ese wnw trending left lateral shear zone deforming at a rate of 2 1 mm yr may exist along the north rim of north china at the latitude of 40 n separating actively extending north china in the south from relatively stable mongolia in the north 2 central and east china move at a rate of 8 11 mm yr east southeast with respect to siberia implying that the overall east southeastward motion is the dominant mode of deformation in east china 3 the india plate moves at a rate of 6 1 mm yr slower than the nuvel 1a model prediction relative to the eurasia plate 4 significant eastward motion 20 2 mm yr with respect to siberia occurs in southeastern tibet about half of this eastward motion 11 mm yr is absorbed by structures along the eastern boundary of the tibetan plateau

slope deposits in the upper nalon river basin nw spain an approach to a quantitative comparison the upper nalon river basin cantabrian mountains nw spain exhibits a variety of slope processes and deposits including landslides rockfall and soil creep geomorphic maps were used to quantitatively ascertain the relationships between these deposits and topographic characteristics of exposure gradient and altitude at the nodes of a square grid with 250 m spacing n 926 a correspondence analysis allows the analysis of qualitative variables lithology and origin of deposit and quantitative variables altitude with a class interval of 200 m and gradient in 10 classes the results suggest that lithology is the main conditioning factor of the differences and similarities between deposits

the age petrogeneis and tectonic significance of the frontenac formation basalts northern new hampshire and western maine within plate basalts are present across the connecticut valley gaspe trough in new england and canada proposed mechanisms for the extensional magmatism include back arc basin extension slab breakoff and extensional collapse the age and composition of the bimodal frontenac formation of northern new england and southern quebec has bearing on the topic we analyzed zircons from the meta felsic rocks of the formation and determined a silurian age of 432 8 ma we also analyzed the frontenac rocks for major and trace elements and compared their compositions to the other mafic rocks along strike in the connecticut valley gaspe trough these include the comerford intrusive suite and the standing pond volcanic member of the waits river formation of vermont the silurian chaleur group and the early devonian dalhousie group of new brunswick and the gaspe peninsula and to the piscataquis belt rocks of northern maine all these rocks are post taconic within plate tholeiites that span an age range from 432 ma frontenac formation to 419 ma comerford intrusive suite in spite of their similar tectonic setting subtle differences in trace element compositions are evident indicating a multiplicity of sources in the production of the siluro devonian magmas ce yb versus la ta values suggest that the frontenac magmas were derived from spinel peridotite sources in the asthenospheric mantle we suggest that slab rollback and back arc basin extension permitted asthenospheric mantle upwelling to the spinel peridotite stability field causing the frontenac partial melting event at depths as low as 35 km sediments of the frontenac formation were deposited as turbidite successions into a developing trough resulting from extension the coeval influx of sediment and intrusion of basalt produced a sediment sill complex because the upward migration of the basaltic magmas was hindered by the rapidly thickening sediment overburden subsequently slab breakoff may have opened an asthenospheric window generating the younger within plate magmas that occurred from 425 to 418 ma across the connecticut valley gaspe trough

geomorphometry and landform mapping what is a landform abstract starting from a concept of the land surface its definition and subdivision from digital elevation models dems is considered high resolution dems from active remote sensing form a new basis for geomorphological work which is moving on from consideration of whether data are accurate enough to how the surface of interest can be defined from an overabundance of data discussion of the operational definition and delimitation of specific landforms of varying degrees of difficulty from craters to mountains is followed by the applicability of fuzzy boundaries scaling usually allometric is shown to be compatible with the scale specificity of many landforms this is exemplified by glacial cirques and drumlins classification of a whole land surface is more difficult than extraction of specific landforms from it well dissected fluvial landscapes pose great challenges for areal analyses these are tackled by the delimitation of homogeneous elementary forms and or land elements in which slope position is considered the boundaries are mainly breaks in gradient or aspect but may also be in some type of curvature breaks in altitude are rare elementary forms or land elements are grouped together into functional regions landforms such as hill sheds it may often be useful to recognise fuzziness of membership or core and periphery of a surface object plains and etched or scoured surfaces defy most of these approaches and general geomorphometry remains the most widely applicable technique it has been applied mainly within arbitrary areas and to some extent to drainage basins but more experimentation with mountain ranges and other landforms or landform regions is needed geomorphological mapping is becoming more specialised and its legends are being simplified its incorporation into geographical information systems gis has required greater precision with definitions and the separation of thematic layers so that it is converging with specific geomorphometry and becoming more flexible and more applicable with a broader range of visualisation techniques

exhumation history of the north central shanxi rift north china revealed by low temperature thermochronology abstract we present new apatite u th sm he ahe n 51 apatite fission track data aft n 12 and zircon u th he zhe n 8 data for two elevation transects in the north central shanxi rift north china low temperature thermochronologic data combined with forward and inverse time temperature history models reveal a precambrian to quaternary thermal history characterized by 1 cooling to 3 5 c ma during the late jurassic to earliest cretaceous yanshanian orogeny 4 a possible ca 120 90 ma reheating event due to elevated geothermal gradients and or local sediment burial 5 late cretaceous ca 110 65 ma cooling contemporaneous with regional extension in eastern asia and denudation of the paleo taihangshan highlands and finally 6 post ca 10 ma cooling associated with extension in the shanxi rift aft dates from the deepest exhumed structural positions of the sampled footwall blocks are mostly 65 ma and ahe dates tend to be highly dispersed within samples aft inverse and ahe forward model results indicate that samples were at temperatures of 750 ppm yield young zhe dates of ca 13 9 ma consistent with late miocene exhumation we argue for the onset of latest cooling by ca 10 ma based on these zhe dates however the precise timing for the onset of rifting remains uncertain the results further suggest that late miocene quaternary extension in the north central shanxi rift is responsible for 2 5 km of exhumation such that published quaternary extension and fault throw rates are significantly 100 higher than long term rates inferred from the thermochronologic data

structure and contents of a new geomorphological gis database linked to a geomorphological map with an example from liden central sweden this paper presents the structure and contents of a standardised geomorphological gis database that stores comprehensive scientific geomorphological data and constitutes the basis for processing and extracting spatial thematic data the geodatabase contains spatial information on morphography morphometry hydrography lithology genesis processes and age a unique characteristic of the gis geodatabase is that it is constructed in parallel with a new comprehensive geomorphological mapping system designed with gis applications in mind this close coupling enables easy digitalisation of the information from the geomorphological map into the gis database for use in both scientific and practical applications the selected platform in which the geomorphological vector raster and tabular data are stored is the esri personal geodatabase additional data such as an image of the original geomorphological map dems or aerial orthographic images are also included in the database the structure of the geomorphological database presented in this paper is exemplified for a study site around liden central sweden

a new symbol and gis based detailed geomorphological mapping system renewal of a scientific discipline for understanding landscape development this paper presents a comprehensive and flexible new geomorphological combination legend that expands the possibilities of current geomorphological mapping concepts the new legend is presented here at scale of 1 10 000 and it combines symbols for hydrography morphometry morphography lithology and structure with colour variations for process genesis and geologic age the piece by piece legend forms a geomorphological alphabet that offers a high diversity of geomorphological information and a possibility for numerous combinations of information this results in a scientific map that is rich in data and which is more informative than most previous maps but is based on a simple legend the system is developed to also be used as a basis for applications in gis the symbol based information in the geomorphological maps can be digitally stored as a powerful database with thematic layers and attribute tables by combining and further developing aspects of different classical mapping systems and techniques into expanded data combinations new possibilities of presentation and storage are developed and thus a strong scientific tool is provided for landscape configuration and the reconstruction of its development in turn the combination paves the way for specific thematic applications the new system is illustrated for two contrasting landscape types the first is located on the border of vorarlberg western austria and liechtenstein in a glacially influenced high altitude alpine setting that is strongly modified by various degradation processes the second area represents a formerly glaciated region in dalarna central sweden near mora an area that is characterized by a variety of aeolian fluvial glaciofluvial and lacustrine depositional and erosional landforms and also reflects isostatic uplift the new method functions well for both areas and results in detailed scientific outlines of both landscape types

delineation of groundwater potential zone in chhatna block bankura district west bengal india using remote sensing and gis techniques groundwater is one of the most valuable natural resources which is an immensely important and dependable source of water supply in all climatic regions over the world groundwater is in demand in areas where surface water supply is inadequate and nonsexist in the chhatna block bankura district and is located on the eastern slope of chotonagpur plateau which is mapped on 73 i 15 73 i 16 and 73 m 3 and falls between latitude 23 10 23 30 n and longitude 86 47 87 02 e it represents plain land and gentle slope which is responsible for infiltration and groundwater recharge the groundwater in this region is confined within the fracture zones and weathered residuum the present investigation is therefore undertaken to delineate potential zones for groundwater development with the help of a remote sensing study irs liss iii data along with other data sets e g existing toposheets and field observation data have been utilized to extract information on the hydrogeomorphic features which include valley fills buried pediment moderate buried pediment shallow and structural hills lineament density contour and slope map of this hard rock terrain the target of this study is to delineate the groundwater potential zones in chhatna block bankura district west bengal satellite imagery along with other data sets has been utilized to extract information on the groundwater controlling features of this study area three features hydrogeomorphology slope and lineaments that influence groundwater occurrences were analyzed and integrated all the information layers have been integrated through gis analysis and the groundwater potential zones have been delineated the weighted index overlay method has been followed to delineate groundwater potential zones the results indicate that good to excellent groundwater potential zones are available in almost the entire block the results show that there is good agreement between the predicted groundwater potential map and the existing groundwater borehole databases the area is characterized by hard rock terrain still due to the presence of planation surface along valley fills it became the prospective zone the area has been categorized into four distinct zones excellent good fair and poor excellent groundwater potential zones constitute 30 35 of the total block area good groundwater potential zones occupy a majority of the block covering approximately 55 60 and the fair potential zones occupy about 10 15 of the total block poor potential zones occupy a very insignificant portion less than 1

spatial distribution of sediment storage types and quantification of valley fill deposits in an alpine basin reintal bavarian alps germany spatial patterns of sediment storage types and associated volumes using a novel approach for quantifying valley fill deposits are presented for a small alpine catchment 17 km 2 in the bavarian alps the different sediment storage types were analysed with respect to geomorphic coupling and sediment flux activity the dominant landforms in the valley in terms of surface area were found to be talus slopes sheets and cones followed by rockfall deposits and alluvial fans and plains more than two thirds of the talus slopes are relict landforms completely decoupled from the geomorphic system notable sediment transport is limited to avalanche tracks debris flows and along floodplains sediment volumes were calculated using a combination of polynomial functions of cross sections seismic refraction and gis modelling a total of 66 seismic refraction profiles were carried out throughout the valley for a more precise determination of sediment thicknesses and to check the bedrock data generated from geomorphometric analysis we calculated the overall sediment volume of the valley fill deposits to be 0 07 km 3 this corresponds to a mean sediment thickness of 23 3 m the seismic refraction data showed that large floodplains and sedimentation areas which have been developed through damming effects from large rockfalls are in general characterised by shallow sediment thicknesses 20 m by contrast the thickness of several talus slopes is more than twice as much for some locations e g narrow sections of valley the polynomial generated cross sections resulted in overestimations of up to one order of magnitude whereas in sections with a moderate valley shape the modelled cross sections are in good accordance with the obtained seismic data for the quantification of valley fill deposits a combined application of bedrock data derived from polynomials and geophysical prospecting is highly recommended d 2003 elsevier b v all rights reserved

late quaternary to decadal velocity fields in asia 1 fields of crustal velocity and strain rate within asia averaged over horizontal distances of 300 km are calculated from estimates of quaternary slip rates on faults and rates of change of lengths of baselines between gps sites the calculated fields fit strain rate components estimated from quaternary slip rates within 95 confidence limits and fit the gps data with an rms residual of 2 5 mm yr 1 the strain rate field constrained only by quaternary slip rates of faults differs from the combined solution at the level of 20 nstrain yr 1 and the differences are explicable by the limited accuracy of geological estimates of slip rate therefore the strain rate fields determined by geodetic measurements taken on the 10 year timescale are consistent with geological observations on the 104 year timescale the combined solution for velocities shows plate or block like motion within deforming asia only in tarim south china and the amurian region elsewhere the kinematics of rigid blocks does not provide a useful description of the motion in particular velocities relative to eurasia point at high angles to contours of their magnitudes not parallel to them as they would if large regions moved as rigid blocks the axes of principal horizontal compressional strain align with topographic gradients in agreement with previous suggestions that asia deforms as a continuum under the influence of gravity

use of digital elevation models to understand and map glacial landforms the case of the canigou massif eastern pyrenees france abstract this paper presents an improved geomorphological methodology that uses remotely sensed data a geographical information system and a brief field campaign to allow rapid yet precise mapping as well as interpretation and analysis of glacial earth surface morphology in high mountain areas the study area consists of the quaternary glaciated part of the coumelade valley canigou massif eastern pyrenees france which ranges between 1450 and 2731 m a s l a topographical map derived digital elevation model was used for analyzing glacial landforms by extracting the slope gradient valley profiles and the slope aspect the results were gradually refined from the interpretations of aerial photograph and the field investigation glacial landforms are present above 1500 m a s l and include glacial and nivation cirques cirque and latero frontal moraines 7 7 106 m and micro scale landforms such as chattermarks crescent grooves and polished surfaces the geomorphological investigation reveals that the quaternary glaciation of the coumelade valley remained limited resulting in a low denudation rate of 0 011 mm yr 1 over the last glacial cycle

strain accumulation in the new madrid and wabash valley seismic zones from 14 years of continuous gps observation the mechanical behavior and hence earthquake potential of faults in continental interiors is an issue of critical importance for the resultant seismic hazard but no consensus has yet been reached on this controversial topic the debate has focused on the central and eastern united states in particular the new madrid seismic zone struck by four magnitude 7 or greater earthquakes in 1811 1812 and to a lesser extent the wabash valley seismic zone just to the north a key aspect of this issue is the rate at which strain is currently accruing on those plate interior faults a quantity that remains debated here we address this issue with an analysis of up to 14 6 years of continuous gps data from a network of 200 sites in the central united states centered on the new madrid and wabash valley seismic zones we find that the high quality sites in these regions show motions that are consistently within the 95 confidence limit of zero deformation these results place an upper bound on strain accrual on faults of 0 2 mm yr and 0 6 mm yr in the new madrid and wabash valley seismic zones respectively for the new madrid region where a paleoseismic record is available for the past 5000 years we argue that strain accrual if any does not permit the 500 900 year repeat time of paleo earthquakes observed in the upper mississippi embayment these results together with increasing evidence for temporal clustering and spatial migration of earthquake sequences in continental interiors indicate that either tectonic loading rates or fault properties vary with time in the new madrid seismic zone and possibly plate wide

taconian orogenesis sedimentation and magmatism in the southern quebec northern vermont appalachians stratigraphic and detrital mineral record of iapetan suturing cambrian ordovician units of the southern quebec appalachians oceanic domain include obducted ophiolites and an overlying syncollisional sedimentary basin represented by the saint daniel melange and flysch units of the magog group these terrains were thrust onto the laurentian continental margin during the taconian orogeny and are unconformably overlain by silurian devonian successor basins this contribution presents and discusses new stratigraphic data acquired in the oceanic domain as well as u pb and 40ar 39ar geochronological data on detrital zircons and muscovites sampled at various stratigraphic levels from the base of the sedimentary units of the oceanic domain and the silurian devonian units of the gaspe belt this work combined with the compilation of existing data for southern quebec and western new england allows a better definition of the tectono stratigraphic evolution of the area and are used to propose correlations with different rock units of the northern new england appalachians which represents a collage of laurentian margin and oceanic units it is shown that cambrian ordovician rocks of southern quebec and northern vermont have undergone a similar tectonic evolution the ophiolites were obducted onto the laurentian margin as a more or less coherent slab of oceanic lithosphere both the ophiolites and continental margin rocks were uplifted eroded and unconformably overlain by middle to late ordovician units of the saint daniel melange and magog group in a forearc setting the presence of mafic and felsic volcanic flows that are interstratified within the saint daniel melange can be correlated with an episode of delamination and slab breakoff during the final stages of obduction and exhumation of the orogenic wedge the magog group was deposited during the emplacement of the taconian nappes as the outboard volcanic arc was still active but progressively shutting down the provenances suggested by the age of the dated detrital minerals can be entirely reconciled with the peri laurentian context of the studied rock units and testify of the tectonic evolution and sedimentary recycling of the taconian orogen from ophiolite obduction onto the laurentian margin to the collapse of the orogenic belt and the formation of successor basins

how the continents deform the evidence from tectonic geodesy space geodesy now provides quantitative maps of the surface velocity field within tectonically active regions supplying constraints on the spatial distribution of deformation the forces that drive it and the brittle and ductile properties of continental lithosphere deformation is usefully described as relative motions among elastic blocks and is block like because major faults are weaker than adjacent intact crust despite similarities continental block kinematics differs from global plate tectonics blocks are much smaller typically 100 1000 km in size departures from block rigidity are sometimes measurable and blocks evolve over 1 10 ma timescales particularly near their often geometrically irregular boundaries quantitatively relating deformation to the forces that drive it requires simplifying assumptions about the strength distribution in the lithosphere if brittle elastic crust is strongest interactions among blocks control the deformation if ductile lithosphere is the stronger its fl

crustal lithospheric structure and continental extrusion of tibet crustal shortening and thickening to c 70 85 km in the tibetan plateau occurred both before and mainly after the c 50 ma india asia collision potassic ultrapotassic shoshonitic and adakitic lavas erupted across the qiangtang c 50 29 ma and lhasa blocks c 30 10 ma indicate a hot mantle thick crust and eclogitic root during that period the progressive northward underthrusting of cold indian mantle lithosphere since collision shut off the source in the lhasa block at c 10 ma late miocene pleistocene shoshonitic volcanic rocks in northern tibet require hot mantle we review the major tectonic processes proposed for tibet including rigid block continuum and crustal flow as well as the geological history of the major strike slip faults we examine controversies concerning the cumulative geological offsets and the discrepancies between geological quaternary and geodetic slip rates low present day slip rates measured from global positioning system and insar along the karakoram and altyn tagh faults in addition to slow long term geological rates can only account for limited eastward extrusion of tibet since mid miocene time we conclude that despite being prominent geomorphological features sometimes with wide mylonite zones the faults cut earlier formed metamorphic and igneous rocks and show limited offsets concentrated strain at the surface is dissipated deeper into wide ductile shear zones

nonlinear characteristics of paleoseismicity in china detailed studies of historical seismicity and paleoseismological data for major late quaternary faults in china reveal spatial and temporal patterns in paleoseismic activity associated with these faults analysis of space time distributions of late quaternary faults and consideration of new models for deformation of the asian continent provide a basis for proposing a division of china and surrounding areas into five active tectonic provinces slip rates for active faults are highest in the himalayan collision zone between the indian and eurasian plates and gradually decrease away from the collision zone into the adjacent active tectonic provinces paleoearthquake recurrence intervals in the active tectonic provinces of china reflect seismogenic properties that are closely related to the position of these provinces relative to the converging indian and eurasian plates average recurrence intervals are 2000 years to as little as 310 900 years for active faults in the qinghai tibetan active tectonic province whereas recurrence intervals are 2000 4500 years in the xinjiang active tectonic province and longer than 2000 years to as much as 7250 years in the north china active tectonic province although average recurrence intervals are closely related to the slip rates of late quaternary faults no simple linear relationship exists between recurrence interval and slip rate further analysis of paleoseismicity on major active faults shows that there are temporal variations in recurrence intervals the case studies also indicate that for some provinces faults or fault segments there are three paleoseismic patterns linear logarithmic and stepped in the logarithmic and stepped patterns the earthquake temporal sequence is characterized by active periods earthquake clusters with relatively short recurrence intervals and quiet periods lack of clustering and relatively long recurrence intervals

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

the use of landslide units in geomorphological mapping an example in the italian dolomites the mapping of processes and landforms found in a particular territory is usually achieved by means of methods and instruments which are universally accepted and adopted such as those of geomorphological mapping in some cases however these methods do not always give complete understanding of a landscape s evolution in particular this happens in environments with a large number of deposits resulting from gravitational processes this paper aims at illustrating an innovative method for mapping gravitational deposits by considering in particular their spatial and temporal relationships and by grouping them into homogeneous units called landslide units the use of these landslide units would facilitate landscape analysis and allow better understanding of areas which are rather complex from the geomorphological standpoint this type of approach is particularly important for application purposes and the dissemination of results on landslide research especially for non specialists within the framework of the teslec project funded by the european union this investigation method has been applied to the area of cortina d ampezzo italian dolomites where more than thirty landslides have been identified and grouped in 12 landslide units these landslide units also incorporate superficial deposits alluvial and lacustrine deposits scree slopes etc genetically linked to the main landslide phenomena each landslide unit includes lower ranked units which may be either landslide bodies or other deposits directly or indirectly related to them as an example the case of the cortina d ampezzo landslide unit is illustrated and discussed

decipherment of potential zones for groundwater occurrence a study in khatra block bankura district west bengal using geospatial techniques groundwater is considered as one of the most valuable natural resources as it supports human civilization freshwater is considered as an important natural resource which occurs partially on the surface and dominantly beneath the surface the resource is declining drastically owing to the rapid increase in population and its management in an improper way the occurrence of groundwater in hard rock terrain still behaves as enigmatic various terrain parameters control the movement and storage of groundwater accordingly geoscientists are using various techniques to explore the potential zone amongst which multi criteria evaluation mce technique seems to be more precise application of remote sensing and geographic information system gis has come out as very effective tools in deciphering groundwater potential zone by modeling terrain features specially in hard rock arid regions the present study is aimed to find out groundwater potential zones in khatra block of bankura district west bengal india characterized by hard granitic terrain and semi arid climatic condition in the present study various thematic maps viz geomorphology geology lineament density drainage density and slope have been prepared for these irs resources at liss 4 with 5 8 m spatial resolution digital data cartosat 1 digital elevation model cartodem with 2 5 m spatial resolution along with other data sets such as survey of india toposheets 73j 13 73i 16 73i 12 gsi map have been used digitized vector maps relating to chosen parameters were converted to raster data using 30 m 30 m grid cell size different theme weight and class rank have been assigned to these raster maps each theme weight has been multiplied by its respective class rank and all the raster thematic layers have been summed up in a linear combination equation in arc gis raster calculator module similarly the weighted layers have been statistically modeled to get the areal extent of groundwater prospects this integrated approach helped in classifying the groundwater availability in the study area into five categories viz very good good moderate poor and very poor finally it can be stated that the modeling assessment method proposed in this study forms an effective tool for delineating groundwater potential zones for proper development and management of groundwater resources in hard rock terrains

paraglacial response of steep sediment mantled slopes to post little ice age glacier recession in the central swiss alps this research assesses the morphological consequences of recent post little ice age paraglacial reworking of valley side sediment mantles in the european alps it aims to identify the extent and conditioning factors of slope adjustment at sites in the swiss alps model the temporal pattern and assess the rates of sediment reworking involved gully systems have cut into steep high level lateral moraines and debris cones have accumulated downslope debris flow is the dominant agent of sediment transfer factors controlling the extent of this activity include moraine slope gradient relief and moisture availability gullies appear to have reached their maximum dimensions within ca 50 yr of deglaciation after which gully relief is reduced by removal of inter gully slopes and gully infilling within 80 140 yr on the most recently deglaciated terrain minimum erosion rates average ca 95 mm yr 1 since gully initiation greatly exceeding normal erosion rates in other environments mean annual accumulation of a single debris cone since ice retreat was calculated to be ca 30 mm yr 1 implications of these findings are applied to patterns of paraglacial sediment mantled slope adjustment conceptualising paraglacial landscape response in terms of a sediment release exhaustion model and paraglacial landform succession copyright 2005 john wiley sons ltd

natural and human impacts on the landscape evolution and hydrography of the chico river basin argentinean patagonia abstract we aimed to assess how geomorphological processes during the cenozoic including those triggered by human intervention modeled the landscape and affected the hydrography of the chico river basin argentinean patagonia we analyzed the hydrography mapped the geomorphology and propose a landscape model of the study area we found the chico river basin geomorphology drainage surface and hydrological regime were affected by paleogene and neogene tectonic uplift pleistocene glaciations holocene climatic change and also the human impact we described four different stages early to late pliocene early to late pleistocene early to middle holocene middle holocene to present of the basin hydrography and drainage surface the main conclusion is that the current boundaries of the chico river basin were established after the mid 20th century formerly the chico river was the downstream extension of the senguer river basin located northwest of the study area with both rivers forming a single system however prevailing arid climatic conditions since the middle holocene together with the climatic variability and anthropogenic activities during the last century produced the current disconnection between the chico and senguer river basins consequently the senguer river basin has changed from exorheic to endorheic and the chico has turned into an intermittent river

geometry kinematics and morphotectonics of the yanqing huailai active faults northern china field studies along the huailai and yanqing mutually parallel neotectonic fault zones lead to a description of morphotectonics and palaeoseismicity as well as the geometry and segmentation of these structures the study emphasizes the kinematics of the region the faults belong to the tectonic interaction between the shanxi rift system and the north china fault system although the general strike of the zones is ne sw the yanqing fault is divided into five segments of nne ssw ene wsw and e w trends and the huailai fault into three segments of ene wsw and e w trends they are mainly pure dip slip normal faults while less often they show oblique slip components the mesostructural quantitative palaeostress analyses local neotectonic active stress pattern indicate a regional nnw sse oriented extension 3 locally deviated to n s nw se wnw ese depending on the fault segment strike the great deviation of fault strikes from the mean and their relation with the basement joint and thrust systems lead to the hypothesis that the neotectonic faults which have a capacity for strong earthquakes follow pre existing inherited structures

present day crustal deformation in china constrained by global positioning system measurements global positioning system gps measurements in china indicate that crustal shortening accommodates most of india s penetration into eurasia deformation within the tibetan plateau and its margins the himalaya the altyn tagh and the qilian shan absorbs more than 90 of the relative motion between the indian and eurasian plates internal shortening of the tibetan plateau itself accounts for more than one third of the total convergence however the tibetan plateau south of the kunlun and ganzi mani faults is moving eastward relative to both india and eurasia this movement is accommodated through rotation of material around the eastern syntaxis the north china and south china blocks east of the tibetan plateau move coherently east southeastward at rates of 2 to 8 millimeters per year and 6 to 11 millimeters per year respectively with respect to the stable eurasia

reconstructing the paleotopography beneath the loess cover with the aid of an electromagnetic induction sensor abstract during the last glacial period weichselian wind blown loess was deposited over the undulating landscape of central belgium which had been formed in surfacing tertiary marine sediments since valleys were filled up with a thicker loess layer than hill tops the present topography is much smoother this smoothing was enhanced by subsequent erosion processes reconstructing the paleolandscape at a detailed scale is almost impossible by conventional procedures based on soil augerings therefore the use of the electromagnetic induction sensor em38dd was evaluated as an alternative for mapping the depth to the tertiary clay substrate on our 2 7 ha study site located in the loess belt of central belgium a strong non linear relationship r 2 0 86 was found between the apparent electrical conductivity eca measured by the vertical dipole orientation of the em38dd and the depth to a tertiary clay substrate these predictions were validated by independent observations of the depth to the tertiary clay and a correlation coefficient of 0 83 with an average error of 0 22 m was found so our dense eca measurements 2 by 2 m resolution allowed us to build a three dimensionall surface of the depth to the tertiary substrate reconstructing the paleotopography beneath the loess cover this paleotopography revealed distinct erosion patterns on the surface of the tertiary clay the continuity of these was confirmed by an analysis of surface flow patterns conducted on the reconstructed paleotopography the non invasive time and cost effective electromagnetic induction sensor was found to offer new perspectives to reconstruct and analyse in detail the quaternary paleotopography beneath the loess cover

glacial and periglacial geomorphology and its paleoclimatological significance in three north ethiopian mountains including a detailed geomorphological map abstract geomorphological investigations and detailed mapping of past and present peri glacial landforms are required in order to understand the impact of climatic anomalies the ethiopian highlands show a great variety in past and contemporary climate and therefore in the occurrence of glacial and periglacial landforms however only a few mountain areas have been studied and detailed geomorphological understanding is lacking in order to allow a fine reconstruction of the impact of the past glacial cycle on the geomorphology vegetation complexes and temperature anomalies a detailed geomorphological map of three mountain areas mt ferrah amba 12 51 n 39 29 e mt lib amba 12 04 n 39 22 and mt abuna yosef 12 08 n 39 11 e was produced in all three study areas inactive solifluction lobes presumably from the last glacial maximum lgm were found in the highest study area of abuna yosef three sites were discovered bearing morainic material from small late pleistocene glaciers these marginal glaciers occurred below the modeled snowline and existed because of local topo climatic conditions evidence of such pleistocene avalanche fed glaciers in ethiopia and africa has not been produced earlier current frost action is limited to frost cracks and small scale patterned ground phenomena the depression of the altitudinal belts of periglacial and glacial processes during the last cold period was assessed through periglacial and glacial landform mapping and comparisons with data from other mountain areas taking latitude into account the depression of glacial and periglacial belts of approximately 600 m implies a temperature drop around 6 c in the last cold period this cooling is in line with temperature depressions elsewhere in east africa during the lgm this study serves as a case study for all the intermediate mountains 3500 4200 m of the north ethiopian highlands

a perched high elevation wetland complex in the atacama desert northern chile and its implications for past human settlement a previously undocumented type of wetland is described from the atacama desert in northern chile 3000 m above sea level sustained exclusively by direct precipitation and perched above the regional water table geomorphological mapping pedostratigraphy geochemistry and analysis of contemporary vegetation is used to understand wetland formation and dynamics during historical and present time periods the paleowetland deposits overlie a miocene tuff that acts as an impermeable barrier to water transfer and creates conditions for local shallow ground water these deposits include several paleosols that were formed during periods when precipitation increased regionally at 7755 7300 1270 545 and 400 300 cal yr bp the similarity in timing with other palaeohydrological records for the atacama implies that paleosols from this wetland are proxies for reconstructing past changes in local and regional hydrological cycle archaeological investigations have revealed the presence of two small farms from the late intermediate period i e during the earliest wetter phase represented by the paleosols both farms are located near the paleowetland deposits which suggests that local inhabitants exploited these water sources during late pre hispanic times results of this study improve knowledge of settlement patterns during this and earlier cultural periods

modelling channel incision and alpine hillslope development using laser altimetry data this paper presents a new approach to simulate drainage basin evolution and demonstrates that high resolution elevation data can be used as useful tool for a dynamic simulation of alpine landscape development in which channel incision is incorporated in high spatial detail a vector channel incision model cim uses 1 m high resolution laser altimetry data for simulation of longitudinal profile development the cim is combined with a grid cell based hillslope erosion model to incorporate the hillslope response to incising bedrock rivers in a simulation of landscape evolution the combined simulation model is applied to a geologically diverse alpine catchment to simulate landscape development from reconstructed late glacial conditions towards the current situation the model is time efficient and realistically adapts to contrasting geological substrata while spatially and temporally variable incision values knick point recession and variable hillslope development result in a realistic simulation of post glacial landscape evolution high resolution elevation data in combination with dynamic geomorphological simulation models facilitate research of complex and difficult to access alpine terrain at greater detail than before it potentially paves the way for more efficient landscape evolution research and can contribute to increasing the understanding of the functioning of geo ecological systems

geospatial technologies and digital geomorphological mapping concepts issues and research geomorphological mapping plays an essential role in understanding earth surface processes geochronology natural resources natural hazards and landscape evolution it involves the partitioning of the terrain into conceptual spatial entities based upon criteria that include morphology form genetics process composition and structure chronology environmental system associations land cover soils ecology as well as spatial topological relationships of surface features landforms historically the power of human visualization was primarily relied upon for analysis introducing subjectivity and biases with respect to selection of criteria for terrain segmentation and placement of boundaries this paper reviews new spatio temporal data and geocomputational approaches that now permit earth scientists to go far beyond traditional mapping permitting quantitative characterization of landscape morphology and the integration of varied landscape thematic information numerous conceptual theoretical and information technology issues are at the heart of digital geomorphological mapping dgm and scientific progress has not kept pace with new and rapidly evolving geospatial technologies consequently new capabilities exist but numerous issues have not been adequately addressed therefore this paper discusses conceptual foundations and illustrates how geomorphometry and mapping approaches can be used to produce geomorphological information related to the land surface and landforms process rates process form relationships and geomorphic systems

tectonic geomorphology in the shanxi graben system northern china abstract the shanxi graben system is composed of a series of normal fault controlled basins which are arranged in an s shaped curve over a distance of about 1200 km active faults mainly trending nne ssw ne sw or ene wsw caused blocks to become rotated and tilted and river courses and terraces to become deformed volcanoes in the datong basin indicate that the formation of the shanxi graben system has a relationship to upper mantle activity and that the tectonic activity was intense during the middle pleistocene arrangement and movement of the faults indicates there has been right lateral shear in this area which may have resulted from the northward push of the qinghai tibet plateau

a thin viscous sheet model for continental deformation summary for the purposes of describing its large scale and long term deformation the continental lithosphere is regarded as a continuum obeying a newtonian or a power law rheology the flow of a thin sheet of power law material overlying an inviscid substrate is studied under the assumption that vertical gradients of the horizontal velocity are negligible a numerical model is used to investigate the deformation of such a sheet under conditions approximating those of continent continent collision the material flows in response to forces applied to its boundaries for example the indenting of one continent by another and to forces in its interior arising from gradients in crustal thickness the horizontal divergence of the flow produces changes in the crustal thickness and hence a time dependent form to the flow itself for a given set of boundary conditions the flow depends on the stress exponent in the power law rheology n and on the argand number which is a measure of the ratio between the stress arising from crustal thickness contrasts and the stress required to deform the material at the ambient strain rates when the effective viscosity of the medium is very high ar o crustal thickness variations do not influence the flow if the material is newtonian n l the deformation associated with an influx of material approximating an indenter is of much greater lateral dimension than the width of the indenter whereas when material has a power law rheology n 3 5 are used the deformation is confined to a region of lateral extent comparable to that of the indenter as ar increases the forces arising from crustal thickness contrasts exert more influence on the flow and the maximum crustal thickness that can be sustained by a given influx of material is related by a simple expression to the effective viscosity of the medium at the ambient strain rates in the limit of a very weak medium ar 10 the lithosphere is unable to sustain appreciable crustal elevation contrasts the results of these numerical experiments show that systems in which the effective viscosities are such that the maximum deviatoric stresses are between 1 kbar

a new velocity field for greece implications for the kinematics and dynamics of the aegean 1 a new set of geodetic velocities for greece and the aegean derived from 254 survey mode and continuous gps sites is used to test kinematic and dynamic models for this area of rapid continental deformation modeling the kinematics of the aegean by the rotation of a small number 3 6 of blocks produces rms misfits of 5 mm yr 1 in the southern aegean and western peloponnese indicating significant internal strain within these postulated blocks it is possible to fit the observed velocities to within 2 3 mm yr 1 rms by models that contain 10 or more blocks but many such models can be found with widely varying arrangements of blocks that fit the data equally well provided that the horizontal dimension of those blocks is not larger than 100 200 km a continuous field of velocity calculated from the gps velocities by assuming that strain rates are homogeneous on the scale of 120 km fits the observed velocities to better than 2 3 mm yr 1 rms with systematic misfits representing more localized strain confined to a region approximately 100 100 km in size around the western gulf of corinth this velocity field accounts for the major active tectonic features of greece and the aegean including the widespread north south extensional deformation and the distributed strike slip deformation in the ne aegean and western greece the t axes of earthquakes are aligned with the principal axes of elongation in the geodetic field major active normal fault systems are perpendicular to those axes and 90 of the large earthquakes in this region during the past 120 years took place within the areas in which the geodetic strain rate exceeds 30 nanostrain yr 1 these observations suggest that the faulting within the upper crust of the aegean region is driven by forces that are coherent over a scale that is significantly greater than 100 km it is likely that those forces arise primarily from differences in gravitational potential energy within the lithosphere of the region

glacial geomorphological mapping a review of approaches and frameworks for best practice geomorphological mapping is a well established method for examining earth surface processes and landscape evolution in a range of environmental contexts in glacial research it provides crucial data for a wide range of process oriented studies and palaeoglaciological reconstructions in the latter case providing an essential geomorphological framework for establishing glacial chronologies in recent decades there have been significant developments in remote sensing and geographical information systems gis with a plethora of high quality remotely sensed datasets now often freely available most recently the emergence of unmanned aerial vehicle uav technology has allowed sub decimetre scale aerial images and digital elevation models dems to be obtained traditional field mapping methods still have an important role in glacial geomorphology particularly in cirque glacier valley glacier and icefield ice cap outlet settings field mapping is also used in ice sheet settings but often takes the form of necessarily highly selective ground truthing of remote mapping given the increasing abundance of datasets and methods available for mapping effective approaches are necessary to enable assimilation of data and ensure robustness this paper provides a review and assessment of the various glacial geomorphological methods and datasets currently available with a focus on their applicability in particular glacial settings we distinguish two overarching work streams that recognise the different approaches typically used in mapping landforms produced by ice masses of different sizes i mapping of ice sheet geomorphological imprints using a combined remote sensing approach with some field checking where feasible and ii mapping of alpine and plateau style ice mass cirque glacier valley glacier icefield and ice cap geomorphological imprints using remote sensing and considerable field mapping key challenges to accurate and robust geomorphological mapping are highlighted often necessitating compromises and pragmatic solutions the importance of combining multiple datasets and or mapping approaches is emphasised akin to multi proxy approaches used in many earth science disciplines based on our review we provide idealised frameworks and general recommendations to ensure best practice in future studies and aid in accuracy assessment comparison and integration of geomorphological data these will be of particular value where geomorphological data are incorporated in large compilations and subsequently used for palaeoglaciological reconstructions finally we stress that robust interpretations of glacial landforms and landscapes invariably requires additional chronological and or sedimentological evidence and that such data should ideally be collected as part of a holistic assessment of the overall glacier system

extension in the graben systems around the ordos china and its contribution to the extrusion tectonics of south china with respect to gobi mongolia the graben basins around the ordos block are major tectonic features of late cenozoic extension in north china this paper gives a synthetic view of the basic characteristics of the graben basins and of the kinematics of the graben bounding faults this view is based on the available geological data spot imagery analysis field observations and focal mechanisms of earthquakes from this region these graben basins have been grouped into two major systems the yinchuan hetao graben system along the northern and northwestern margins of the ordos and the weihe shanxi graben system along the southern and eastern margins of the ordos crustal deformation along these graben systems involves normal slip on ne sw striking graben bounding faults normal right lateral and normal left lateral slip on nne ssw and wnw ese striking faults respectively this fault pattern is consistent with nw se trending extension the amount and rate of deformation resulting from this extension have been estimated from geological data using a cross sectional area balance and the extensional factor method deduced from the tilt of faulted blocks the results of these estimates show that the uppermost pliocene quaternary extension rate in a nw se direction is in the order of 1 6 mm yr 1 across the weihe graben 0 5 mm yr 1 across the central shanxi graben on the southeastern margin of the ordos block and 3 1 mm yr 1 across the linhe graben on the northwestern margin of the ordos block the extension across these graben systems is accompanied with counterclockwise rotation of continental blocks in north china ordos taihang shan north china plain a kinematic model is proposed in which the late cenozoic extension and block rotation in north china are interpreted as the effect of the eastward termination of the left lateral slip haiyuan fault and kunlun taibai fault system the ordos block rotates counterclockwise as a result of the push of tibet through the left lateral strike slip haiyuan fault and the liupan shan thrust and fold belt the extension along the weihe shanxi graben system may represent the effect of the left lateral slip on the kunlun taibai qinling fault system the rough estimates of the extensional deformation around the ordos block indicate that this contributes to about 5 2 mm yr 1 of left lateral movement in a n125 e direction between south china and gobi mongolia this motion adds to the left lateral slip on the qinling fault zone about 7 2 mm yr 1 in a n90 e direction between the qinling shan and the hua shan north china thus the eastward motion of south china with respect to gobi mongolia is partitioned between normal faulting around the ordos and strike slip faulting in the qinling shan it is estimated to be in the order of 12 4 mm yr 1 in a n105 e direction during the quaternary

neotectonic activity along the shanxi rift system china abstract the shanxi rift system is one of the most outstanding pliocene quaternary continental rift systems and strong earthquake belts in china it extends as a series of en echelon left stepping asymmetrical half graben basins on the shanxi highlands over a distance of more than 1200 km it describes a sinous s shaped curve with a nne trending transtensional segment in the middle and ne ene trending extensional domains on both terminal segments the latter are characterized by apparently synchronous high angle normal faulting accommodating large vertical and relatively smaller lateral strains 3 5 8 5 which produces the modern basin and range structure the rift system has been intermittently active since the pliocene geomorphological neotectonic and seismic studies indicate that the rift system is at present still developing as demonstrated by the occurrence of strong destructive historical earthquakes of magnitudes 7 8 and the large slip rates on the nne trending transtensional faults in the middle segment the slip rates of these faults reached 4 9 6 4 mm per year during the holocene geophysical studies show that the rifting occurred in a thickened crust and no compelling evidence exists for the major thermal event in the mantle uniquely associated with the rifting the development of the shanxi rift system is consistent with the regional brittle strain pattern of a right lateral shear belt and a regional stress field of ene wsw compression and nnw sse extension of the north china subplate this structural setting corroborates the hypothesis that the deformation is in response to the escape tectonics caused by the himalayan indenter from the southwest and at the same time by the counter clockwise rotation of the intervening crustal blocks this provides the mode of formation of the shanxi rift system

active extension of the shanxi rift north china does it result from anticlockwise block rotations the shanxi rift is an intraplate extensional zone in the north china block active extension has previously been considered to result from anticlockwise block rotation with successive indentation of the indian plate toward the eurasian plate however gps data show that the entire north china block is moving coherently from wnw to ese indicating that no significant block rotations presently exist along the two sides of the rift we use a viscoelastic model to predict that its active extension might be caused by intraplate deformation localization with lateral changes of the crustal rheological structures a model result shows that for the ese movement of the north china block the existing topographical loading and crustal weakness could have resulted in the obvious long term extension of the shanxi rift even without different block rotations the surface extension rate approximated from lateral inhomogeneous crustal models is 0 5 1 4 mm yr 1 consistent with observed geological and seismological extension rates

new geomorphological mapping system used at different scales in a swedish glaciated area abstract a new detailed geomorphological mapping system is tested at different scales for presentation of landscape configuration and interpretation of landscape development of a formerly glaciated area near mora in central sweden the geomorphological maps are based on fieldwork supported by aerial photographs the area contains landforms created by mass movement glacial glaciofluvial fluvial lacustrine aeolian and anthropogenic processes in addition geomorphological effects of isostatic uplift which has caused a c 220 m rise of the former ancylus lake shoreline in the area since the deglaciation can be seen the new system is tested at scales 1 5000 1 25 000 and 1 50 000 using the same legend at the largest scale information on morphography morphometry lithology and hydrography are included in the map as are details on polygenetic origins of landforms with each step from the 1 5000 to the 1 50 000 scale some generalisation is needed at the cost of descriptive detail in turn with smaller scale the general overview of the area increases and the impression from the map gradually becomes more dominated by genesis the emphasis of the map thus changes from a presentation with a high level of descriptive information at the largest scale to a more interpretative overview at smaller scales the scale transformation shows that the geomorphological presentation of the landscape is a function of both the landscape hierarchy and the geomorphological context within an area the use of the new geomorphological mapping system at the three scales shows that the tested mapping legend can be used without modification from one scale to another this is mainly because the geomorphological information parameters are separated in the legend and that explanatory information is gained from combinations of them the possibility to apply the same legend at different scales for an area facilitates the choice of an appropriate mapping scale for specific purposes and applications the new mapping system also has the advantage that the data can be easily transformed into a gis esri geodatabase containing the same raw data as the original map the differences of information at the different scales illustrate problems that are also relevant for use and presentation of geomorphological data in a gis and three examples of scale problems in relation to gis data handling are outlined

historical seismicity and rates of crustal deformation along the margins of the ordos block north china earthquakes in china show an empirical relation between seismic moment m 0 and the areal distribution of modified mercalli intensities vi and viii log m 0 16 66 0 91 log a viii and log m 0 14 35 1 16 log a vi where a and m 0 are measured in squared kilometers and newton meter respectively the empirical relations may be used to estimate m 0 for historical earthquakes in china to within a factor of three on average when sufficient isoseismal data exist this observation and an extensive collection of isoseismal maps are used to estimate m 0 for large earthquakes that occurred along the margins of the ordos block during the last 700 yr focal parameters of the historical events are inferred from the orientation and displacements across quaternary faults average rates of crustal deformation are then estimated from the 700 yr historical record with formulas that relate the occurrence rate of seismic moment in a region to rates of crustal strain the shanxi and northern ningxia graben systems are situated along the eastern and northwestern edges of the ordos block respectively normal faults in the two systems trend northeasterly and are characterized by a component of right lateral slip the deformation resulting from slip during earthquakes in each of the respective fault systems is estimated at about 0 5 to 1 0 mm yr of both right lateral shear and north by northwest extension the weihe graben system bounds the southern edge of the ordos block strikes easterly and conjugate to the shanxi and northern ningxia fault systems and exhibits left lateral normal fault displacements the average rate of deformation across weihe is described by about 1 0 mm yr of north by northwest extension and 1 5 mm yr left lateral east west shear the hetao fault system delineates the northern edge of the ordos block and displays quaternary faults similar in orientation and mechanism to that observed in weihe although mapped faults in hetao exhibit evidence of quaternary displacement crustal deformation rates are not estimated because there exists no historical record of large earthquakes in the area in southern ningxia at the southwest boundary of the ordos block deformation occurs by slip on left lateral strike slip faults oriented in an easterly azimuth and thrust faults with strikes ranging from southeast to south the average deformation rate in southern ningxia is found to be about 4 0 mm yr of east by northeast contraction and 10 0 mm yr of left lateral shear deformation of each of the fault systems is consistent with a regional compressive stress that trends northeast and results in an average of about 3 0 mm yr each of contraction at n70 e and extension of n160 e across the entire region inasmuch as uncertainties in estimates of m0 for historical earthquakes are about a factor of three a similar uncertainty is attached to rates of crustal strain determined in this manner

comparing models of debris flow susceptibility in the alpine environment abstract debris flows are widespread in val di fassa trento province eastern italian alps where they constitute one of the most dangerous gravity induced surface processes from a large set of environmental characteristics and a detailed inventory of debris flows we developed five models to predict location of debris flow source areas the models differ in approach statistical vs physically based and type of terrain unit of reference slope unit vs grid cell in the statistical models a mix of several environmental factors classified areas with different debris flow susceptibility however the factors that exert a strong discriminant power reduce to conditions of high slope gradient pasture or no vegetation cover availability of detrital material and active erosional processes since slope and land use are also used in the physically based approach all model results are largely controlled by the same leading variables overlaying susceptibility maps produced by the different methods statistical vs physically based for the same terrain unit of reference grid cell reveals a large difference nearly 25 spatial mismatch the spatial discrepancy exceeds 30 for susceptibility maps generated by the same method discriminant analysis but different terrain units slope unit vs grid cell the size of the terrain unit also led to different susceptibility maps almost 20 spatial mismatch maps based on different statistical tools discriminant analysis vs logistic regression differed least less than 10 hence method and terrain unit proved to be equally important in mapping susceptibility model performance was evaluated from the percentages of terrain units that each model correctly classifies the number of debris flow falling within the area classified as unstable by each model and through the metric of roc curves although all techniques implemented yielded results essentially comparable the discriminant model based on the partition of the study area into small slope units may constitute the most suitable approach to regional debris flow assessment in the alpine environment

the cenozoic tectonic evolution of the great north china two types of rifting and crustal necking in the great north china and their tectonic implications abstract the great north china underwent widespread continental rifting during cenozoic time that caused extension and necking of the crust in this area and formed four major rift systems in this paper we provide geological and geophysical evidence that rifting and extension in the western part of the great north china differs from that in its eastern part in age and nature the space time relationships show that the origins of the western rift group of the great north china are probably related to the tibet plateau tectonics whereas those of the eastern rift group are related to the subduction events in the western margin of the pacific plate furthermore the quaternary tectonic regime in the eastern part of the great north china differs from the neogene tectonic pattern and shows relations with western rifts we speculate that during the quaternary the processes that caused rifting in the west have spread further east and now affect the eastern part of the great north china

geochemistry and origin of metamorphosed mafic rocks from the lower paleozoic moretown and cram hill formations of north central vermont delamination magmatism in the western new england appalachians

the ce 1303 hongdong earthquake and the huoshan piedmont fault shanxi graben implications for magnitude limits of normal fault earthquakes the ce 1303 hongdong earthquake with 270 000 deaths has been suggested as the first magnitude 8 earthquake recorded in north china we use 31 ams 14c ages to date earthquakes recorded in the huoshan piedmont fault which is interpreted to be the causative fault for the event we interpret fault traces and map the hongdong earthquake surface rupture in detail four events are identified with timings constrained at 1 060 590 year bp corresponding to the common era 1303 event 3 310 3 210 year bp 5 460 5 380 year bp and 26 380 year bp respectively the later three events have a recurrence interval of 2 000 3 000 years we find that the hongdong earthquake had a rupture length of 98 km a maximum throw of 5 0 m and a best estimate for magnitude in the range mw 7 2 7 6 we suggest that previous magnitude estimates are overestimates normal fault earthquakes have smaller upper limits to their magnitudes than thrusts because their relatively steep dips produce intersections at the base of the seismogenic layer at smaller downdip widths than gently dipping thrust faults the hongdong event was not an exception to this pattern the historic released seismic moment may be closer to the accumulated moment than previously calculated

object based classification of global undersea topography and geomorphological features from the srtm30_plus data the analysis of undersea topography and geomorphological features provides necessary information to related disciplines and many applications the development of an automated knowledge based classification approach of undersea topography and geomorphological features is challenging due to their multi scale nature the aim of the study is to develop and evaluate an automated knowledge based obia approach to i decompose the global undersea topography to multi scale regions of distinct morphometric properties and ii assign the derived regions to characteristic geomorphological features first the global undersea topography was decomposed through the srtm30 plus bathymetry data to the so called morphometric objects of discrete morphometric properties and spatial scales defined by data driven methods local variance graphs and nested means and multi scale analysis the derived morphometric objects were combined with additional relative topographic position information computed with a self adaptive pattern recognition method geomorphons and auxiliary data and were assigned to characteristic undersea geomorphological feature classes through a knowledge base developed from standard definitions the decomposition of the srtm30 plus data to morphometric objects was considered successful for the requirements of maximizing intra object and inter object heterogeneity based on the near zero values of the moran s i and the low values of the weighted variance index the knowledge based classification approach was tested for its transferability in six case studies of various tectonic settings and achieved the efficient extraction of 11 undersea geomorphological feature classes the classification results for the six case studies were compared with the digital global seafloor geomorphic features map gsfm the 11 undersea feature classes and their producer s accuracies in respect to the gsfm relevant areas were basin 95 continental shelf 94 9 trough 88 4 plateau 78 9 continental slope 76 4 trench 71 2 abyssal hill 62 9 abyssal plain 62 4 ridge 49 8 seamount 48 8 and continental rise 25 4 the knowledge based obia classification approach was considered transferable since the percentages of spatial and thematic agreement between the most of the classified undersea feature classes and the gsfm exhibited low deviations across the six case studies

nailing down the slip rate of the altyn tagh fault 1 previous estimates of the geodetic and geologic slip rates of the 1500 km long altyn tagh fault bordering the northern edge of the tibetan plateau vary by a factor of five proposed reasons for these discrepancies include poor gps geometry interpretative errors in terrace morphology and changes in fault slip rate over time here we present results from a new dense gps array orthogonal to the fault at 86 2 e that indicates a velocity of 9 0 3 2 4 4 mm yr in close agreement with geomorphologic estimates at the same location our estimated geodetic slip rate is consistent with recent geological slip rates based on terrace offsets the resulting mean combined geological and geodetic slip rate 9 0 4 0 mm yr is remarkably uniform for the central 800 km of the altyn tagh fault significantly lower than early kinematic estimates and consistent with deformation elsewhere in tibet and central asia

extension rates across the northern shanxi grabens china from quaternary geology seismicity and geodesy discrepancies between geological seismic and geodetic rates of strain can indicate that rates of crustal deformation and hence seismic hazard are varying through time previous studies in the northern shanxi grabens at the northeastern corner of the ordos plateau in northern china have found extension rates of anywhere between 0 and 6 mm a at an azimuth of between 95 and 180 in this paper we determine extension rates across the northern shanxi grabens from offset geomorphological features and a variety of quaternary dating techniques including new irsl and ar ar ages a kostrov summation using a 700 year catalogue of historical earthquakes and recent campaign gps measurements we observe good agreement between quaternary seismic and geodetic rates of strain and we find that the northern shanxi grabens are extending at around 1 to 2 mm a at an azimuth of 151 the azimuth of extension is particularly well constrained and can be reliably inferred from catalogues of small earthquakes we do not find evidence for any substantial variations in extension rate through time though there is a notable seismic moment rate deficit since 1750 this deficit could indicate complex fault interactions across large regions aseismic accommodation of deformation or that we are quite late in the earthquake cycle with the potential for larger earthquakes in the relatively near future

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

seismic velocity structure of the crust and shallow mantle of the central and eastern united states by seismic surface wave imaging seismic surface waves from the transportable array of earthscope s usarray are used to estimate phase velocity structure of 18 to 125 s rayleigh waves then inverted to obtain three dimensional crust and upper mantle structure of the central and eastern united states ceus down to 200 km the obtained lithosphere structure confirms previously imaged ceus features e g the low seismic velocity signature of the cambrian reelfoot rift and the very low velocity at 150 km depth below an eocene volcanic center in northwestern virginia new features include high velocity mantle stretching from the archean superior craton well into the proterozoic terranes and deep low velocity zones in central texas associated with the late cretaceous travis and uvalde volcanic fields and beneath the south georgia rift which contains jurassic basalts hot spot tracks may be associated with several imaged low velocity zones particularly those close to the former rifted laurentia margin

the effectiveness of hillshade maps and expert knowledge in mapping old deep seated landslides large deep seated landslides with a shear surface deeper than 3 m and a mean affected area of 4 2 ha are common features in the flemish ardennes none of these deep seated landslides are dated but they are assumed to be rather old 100 years because most of these landslides are located under forest aerial photo interpretation commonly used for the creation of landslide inventories is not a suitable tool to map the landslides in the flemish ardennes therefore an intensive 100 day field survey was carried out by two geomorphologists in a 430 km 2 study area this resulted in a landslide inventory map indicating the location of 135 large deep seated landslides but field surveys are time consuming and thus very expensive therefore a cheaper and faster mapping technique was tested a hillshade map was constructed for the study area in a gis idris132 from a 5 m resolution digital elevation model dem seven experts were given 1 h to indicate all the hillslope sections which they suspected to be possible landslides on a copy of the aforementioned map scale 1 100 000 in total this exercise took only 1 day i e 7 person hours large differences in the number of presumed landslides and the extent of the hillslopes thought to be affected by landslides were reported among the seven experts the polygon and pixel efficiency were introduced to estimate the quality of the landslide maps based on hillshade maps and expert knowledge compared to the field survey based landslide inventory the quality of the landslide inventories based on the hillshade maps and expert knowledge was relatively low experts familiar with the study area obtained somewhat better results than experts who visited the study area only once a combination of the seven expert maps did not result in a good inventory map because too many unaffected hillslopes were incorrectly indicated as affected by landslides the results obtained in this study are comparable to an investigation carried out by wills c j mccrink t p 2002 comparing landslide inventories the map depends on the method environmental and engineering geoscience 8 279 293 although the tested method can never replace a detailed field survey taking into account the proposed improvements it can be used for the creation of a regional inventory map of old landslides in a densely forested area where light detection and ranging lidar data are unavailable c 2004 elsevier b v all rights reserved

is there a discrepancy between geological and geodetic slip rates along the san andreas fault system previous inversions for slip rate along the san andreas fault system safs based on elastic half space models show a discrepancy between the geologic and geodetic slip rates along a few major fault segments in this study we use an earthquake cycle model representing an elastic plate over a viscoelastic half space to demonstrate that there is no significant discrepancy between long term geologic and geodetic slip rates the california statewide model includes 41 major fault segments having steady slip from the base of the locked zone to the base of the elastic plate and episodic shallow slip based on known historical ruptures and geologic recurrence intervals the slip rates are constrained by 1981 secular velocity measurements from gps and l band intereferometric synthetic aperture radar a model with a thick elastic layer 60 km and half space viscosity of 1019pa s is preferred because it produces the smallest misfit to both the geologic and the geodetic data we find that the geodetic slip rates from the thick plate model agrees to within the bounds of the geologic slip rates while the rates from the elastic half space model disagree on specific important fault segments such as the mojave and the north coast segment of the san andreas fault the viscoelastic earthquake cycle models have generally higher slip rates than the half space model because most of the faults along the safs are late in the earthquake cycle so today they are moving slower than the long term cycle averaged velocity as governed by the viscoelastic relaxation process

magnitude frequency relationships of debris flows and debris avalanches in relation to slope relief abstract probability of occurrence hazard intensity and encounter probability are key parameters in the quantitative risk analysis qra of landslides all are strongly dependent on magnitude of the landslides as a result magnitude frequency analysis should be a part of qra deriving representative magnitude frequency relationships for debris avalanches and debris flows however is difficult one key problem is illustrated with the example of a unique database from the coastal region of british columbia canada which was compiled entirely from detailed ground investigations the magnitude of debris avalanches and debris flows is not an independent statistical quantity but a function of the scale of a given slope as characterized by the slope length thus attempting to derive probability and magnitude for a given location or sub region from a regionally derived magnitude frequency curve may lead to incorrect predictions the same problem is pertinent to the application of the same approach to any type of landslide in which the largest combined dimension of the source volume including entrainment is of the same order as the length of the slope it is recommended that greater emphasis be placed on site specific geological observations at the expense of generalized statistics

quantifying near field and off fault deformation patterns of the 1992 mw 7 3 landers earthquake coseismic surface deformation in large earthquakes is typically measured using field mapping and with a range of geodetic methods e g insar lidar differencing and gps current methods however either fail to capture patterns of near field coseismic surface deformation or lack preevent data consequently the characteristics of off fault deformation and the parameters that control it remain poorly understood we develop a standardized method to fully measure the surface near field coseismic deformation patterns at high resolution using the cosi corr program by correlating pairs of aerial photographs taken before and after the 1992 m w 7 3 landers earthquake cosi corr offers the advantage of measuring displacement across the entire zone of surface deformation and over a wider aperture than that available to field geologists for the landers earthquake our measured displacements are systematically larger than the field measurements indicating the presence of off fault deformation we show that 46 of the total surface displacement occurred as off fault deformation over a mean deformation width of 154 m the magnitude and width of off fault deformation along the rupture is primarily controlled by the macroscopic structural complexity of the fault system with a weak correlation with the type of near surface materials through which the rupture propagated both the magnitude and width of distributed deformation are largest in stepovers bends and at the southern termination of the surface rupture we find that slip along the surface rupture exhibits a consistent degree of variability at all observable length scales and that the slip distribution is self affine fractal with dimension of 1 56

can vertical migrations of dinoflagellates explain observed bioluminescence patterns during an upwelling event in monterey bay california 1 extensive auvs surveys showed that during the development of upwelling bioluminescent dinoflagellates from the northern part of the monterey bay california called the upwelling shadow area were able to avoid advection by southward flowing currents along the entrance to the bay while non bioluminescent phytoplankton were advected by currents it is known that vertical swimming of dinoflagellates to deeper layers helps them avoid losses due to advection in the present paper we investigate if modeling dinoflagellates vertical swimming can explain the observed dinoflagellates ability to avoid advection during the upwelling development the dynamics of a dinoflagellate population is modeled with the tracer model with introduced vertical swimming velocity three swimming behaviors are considered sinking swimming to the target depth and diel vertical migration velocities in all swimming cases are considered in the ranges of documented velocities for the observed dinoflagellates species during the upwelling development in the monterey bay our modeling confirmed that observed bioluminescent dinoflagellates avoidance of advection during the upwelling development can be explained by their vertical swimming ability in the case of swimming with 20 m day which is half of observed maximum swimming velocity around 40 of dinoflagellates population from the northern part of the bay were advected along the entrance to the bay in comparison to the case without swimming this is in agreement with the ratio of around 45 of observed mean bioluminescence intensity at the entrance to the bay to the observed mean intensity in the northern part of the bay this mechanism also helps explain the general persistence of dinoflagellates in this part of the coastline

seismic strain rates in regions of distributed continental deformation we compare the rates and configurations of seismic deformation determined from moment tensor mechanisms of earthquakes in five continental regions with the rates and configurations expected if the seismicity reflected the relative plate motions in the regions the five regions the aegean iran california western new guinea and central asia are characterized by high levels of seismicity distributed over hundreds to thousands of kilometers from the accepted plate boundaries the earthquake mechanisms are compiled primarily from the catalog of centroid moment tensor solutions which is nearly complete over the interval 1977 1987 for earthquakes greater than ms 5 the thickness of the seismogenic layer in each region is constrained by the results of modeling broadband body wave phases and of previous earthquake studies in the aegean california and western new guinea the observed configurations of deformation agree with a simple model of distributed accommodation of relative plate motion in iran and central asia the moment tensors indicate that there is appreciable strain parallel to the strikes of the belts we augment our 10 year estimates of seismic deformation with the available historical moment and magnitude estimates for the five regions and find that moderate and large earthquakes account for between 25 and 70 of the deformation of the seismogenic layer

mapping geomorphology a journey from paper maps through computer mapping to gis and virtual reality abstract maps are integral components of research in geomorphology and quaternary geology visual presentation of the spatial and temporal distribution of a phenomenon often provides clues to the process es that generated the phenomenon compiling information on maps interpreting spatial patterns and using standard topographic maps were fundamental parts of the undergraduate experience why have such experiences been slowly disappearing from undergraduate curricula how are geology majors taught map scale map projections and the pitfalls associated with the display of spatial information neglect in preserving the mapping tradition places the geology major at a disadvantage the use of maps and mapping is undergoing a renaissance use in the classroom has a bright future because of digital scanning computer cartography geographic information systems gis and virtual reality pen and ink techniques should be relegated to museums pencil sketches can be scanned and perfect products generated every time these techniques however do not eliminate the need for basic map knowledge such as scale projections and generalization what assumptions about map projections have been built into the software how are spatial data and attribute data integrated into the resultant map in a geographic information system gis because the application of virtual reality to geomorphic processes looms on the horizon geologists must recognize how the current spatial revolution can help with the assessment of geologic phenomena and teach students to function with the new technology

expert driven semi automated geomorphological mapping for a mountainous area using a laser dtm in this paper a semi automated method is presented to recognize and spatially delineate geomorphological units in mountainous forested ecosystems using statistical information extracted from a 1 m resolution laser digital elevation dataset the method was applied to a mountainous area in austria first slope angle and elevation characteristics were determined for each key geomorphological unit occurring in the study area second a map of slope classes derived from the laser dtm was used in an expert driven multilevel object oriented approach the resulting classes represent units corresponding to landforms and processes commonly recognized in mountain areas fluvial terrace alluvial fan slope with mass movement talus slope rock cliff glacial landform shallow incised channel and deep incised channel the classification result was compared with a validation dataset of geomorphological units derived from an analogue geomorphological map for the above mentioned classes the percentages of correctly classified grid cells are 69 79 50 64 32 61 23 and 70 respectively the lower values of 32 and 23 are mainly related to inaccurate mapping of rock cliffs and shallow incised channels in the analogue geomorphological map the accuracy increased to 76 and 54 respectively if a buffer is applied to these specific units it is concluded that high resolution topographical data derived from laser dtms are useful for the extraction of geomorphological units in mountain areas

triggering conditions and mobility of debris flows associated to complex earthflows landslides on black marl slopes of the french alps are in most cases complex catastrophic failures in which the initial structural slides transform into slow moving earthflows under specific hydrological conditions these earthflows can transform into debris flows due to their sediment volume and their high mobility debris flow induced by landslides are far much dangerous than these resulting from continuous erosive processes a fundamental point to correctly delineate the area exposed to debris flows on the alluvial fans is therefore to understand why and how some earthflows transform into debris flow while most of them stabilize in this paper a case of transformation from earthflow to debris flow is presented and analysed an approach combining geomorphology hydrology geotechnics and rheology is adopted to model the debris flow initiation failure stage and its runout postfailure stage using the super sauze earthflow alpes de haute provence france as a case study the objective is to characterize the hydrological and mechanical conditions leading to debris flow initiation in such cohesive material results show a very good agreement between the observed runout distances and these calculated using the debris flow modeling code cemagref 1 d the deposit thickness in the depositional area and the velocities of the debris flows are also well reproduced furthermore a dynamic slope stability analysis shows that conditions in the debris source area under average pore water pressures and moisture contents are close to failure a small excess of water can therefore initiate failure seepage analysis is used to estimate the volume of debris that can be released for several hydroclimatic conditions the failed volumes are then introduced in the cemagref 1 d runout code to propose debris flow hazard scenarios results show that clayey earthflow can transform under 5 year return period rainfall conditions into 1 km runout debris flow of volumes ranging between 2000 to 5000 m 3 slope failures induced by 25 year return period rainfall can trigger large debris flow events 30 000 to 50 000 m 3 that can reach the alluvial fan and cause damage

is the shanxi rift of northern china extending 1 the shanxi rift in northern china is marked by intensive seismicity including many devastating historic earthquakes geological and seismological evidence show 0 5 1 6 mm yr extension across the rift and previous gps results indicated an extension rate of 4 2 mm yr we show here newly compiled gps data that indicate coherent crustal motion and no clear sign of extension across the rift we reconcile the discrepancy between geological observations and gps results in a simple viscoelastic finite element model with timescale dependent crustal deformation the gps velocities can be fit by a model with a near elastic upper crust consistent with predominantly interseismic deformation the geological rate of extension is predicted when viscous creep of the crust is dominant driven by the gravitational potential energy arising from the heterogeneity of crustal structure

geodynamics of the shanxi rift system china the pliocene quaternary shanxi rift system of northern china transsects the domal axis of the shanxi highlands and is defined by an s shaped string of asymmetric basins extending from huailai yanqing in the north via taiyuan to yuncheng in the south this rift system has a length of about 1200 km and a width of 20 80 km it is characterized by strong earthquakes its central nne trending transtensional segment forms the main element of the shanxi rift system basin subsidence commenced during the early pliocene along nne oriented master faults characterized by large strike slip rates 5 68 7 mm yr crustal extension amounts to some 1 4 km basins are separated by push up blocks destructive earthquakes m 7 8 are unevenly distributed the ene trending northern and southern branches of the shanxi rift system are characterized by orthogonal crustal extension along ene striking normal faults amounting to about 8 km these areas are characterized by a basin and range type structural style and weak seismic activity the shanxi rift system developed on a some 40 km thick thermally cool precambrian crustal segment that was overprinted during mesozoic diastrophic events there is only minor rift related volcanic activity the moho is pulled up by a few kilometers only under the axial rift zone sub moho compressional velocities are in the 8 0 8 1 km s range the shanxi rift system evolved in response to the build up of regional stress fields related to the collision of india and eurasia its localization involved reactivation of pre existing fracture systems

geomorphological and structural characterization of the southern weihe graben central china implications for fault segmentation abstract the cenozoic graben systems around the tectonically stable ordos block central china have been considered as ideal places for investigating active deformation within continental rifts such as the weihe graben at the southern margin with high historical seismicity e g 1556 m 8 5 huaxian great earthquake however previous investigations have mostly focused on the active structures in the eastern and northern parts of this graben by contrast in the southwest tectonic activity along the northern margin of the qinling mountains has not been systematically investigated yet in this study based on digital elevation models dems we carried out geomorphological analysis to evaluate the relative tectonic activity along the whole south border fault sbf on the basis of field observations high resolution dems acquired by small unmanned aerial vehicles suva using structure for motion techniques radiocarbon 14c age dating we demonstrate that 1 tectonic activity along the sbf changes along strike being higher in the eastern sector 2 seven major segment boundaries have been assigned where the fault changes its strike and has lower tectonic activity 3 the fault segment between the cities of huaxian and huayin characterized by almost pure normal slip has been active during the holocene we suggest that these findings would provide a basis for further investigating on the seismic risk in densely populated weihe graben

properties of debris flow deposits and source materials compared implications for debris flow characterization in the alps debris flow deposits generally contain 5 clay size particles and the role of the surface charged 2 mu m particles is often neglected although these particles may have a significant impact on the rheological properties of the interstitial fluid the objective of this study was to compare debris flow deposits and parent materials from two neighbouring catchments of the swiss alps with special emphasis on the colloidal constituents the catchments are small in area 4 km 2 2 5 km long similar in morphology but different in geology the average slopes are 35 40 the catchments were monitored for debris flow events and mapped for surface aspect and erosion activity debris flow deposits and parent materials were sampled the clay and silt fractions extracted and the bulk density 2 mm fraction bulk density particle size distribution chemical composition cation exchange capacity cec and mineralogy analysed the results show that the deposits are similar to the parent screes in terms of chemical composition but differ in terms of i particle size distribution and ii mineralogy reactivity and density of the 2 mm fraction in this fraction compared with the parent materials the deposits show dense materials enriched in coarse monocrystalline particles of which the smallest and more reactive particles were leached the results suggest that deposit samples should not be considered as representative of source or flow materials particularly with respect to their physical properties

gis based landslide susceptibility mapping for the 2005 kashmir earthquake region abstract the m w 7 6 october 8 2005 kashmir earthquake triggered several thousand landslides throughout the himalaya of northern pakistan and india these were concentrated in six different geomorphic geologic anthropogenic settings a spatial database which included 2252 landslides was developed and analyzed using aster satellite imagery and geographical information system gis technology a multi criterion evaluation was applied to determine the significance of event controlling parameters in triggering the landslides the parameters included lithology faults slope gradient slope aspect elevation land cover rivers and roads the results showed four classes of landslide susceptibility furthermore they indicated that lithology had the strongest influence on landsliding particularly when the rock is highly fractured such as in shale slate clastic sediments and limestone and dolomite moreover the proximity of the landslides to faults rivers and roads was also an important factor in helping to initiate failures in addition landslides occurred particularly in moderate elevations on south facing slopes shrub land grassland and also agricultural land were highly susceptible to failures while forested slopes had few landslides one third of the study area was highly or very highly susceptible to future landsliding and requires immediate mitigation action the rest of the region had a low or moderate susceptibility to landsliding and remains relatively stable this study supports the view that 1 earthquake triggered landslides are concentrated in specific zones associated with event controlling parameters and 2 in the western himalaya deforestation and road construction contributed significantly to landsliding during and shortly after earthquakes

the contribution of geomorphological mapping to sediment transfer evaluation in small alpine catchments the assessment of sediment transfer processes is necessary to understand the hydro geomorphological functioning of small alpine watersheds prone to channelised debris flows because their occurrence often depends on the amount of debris available in the gully systems therefore sediment budgets should be studied through the identification of erosion transport and deposition processes sediment transfer processes were investigated in a small catchment by field measurements and more specifically through the application of a process based geomorphological mapping method the proposed methodology is based on data directly derived from gis analysis using high resolution dem field measurements and aerial photograph interpretations it has been conceived to estimate sediment transfer dynamics taking into account the role of different sediment stores in the torrential system the proposed geomorphological mapping methodology is quite innovative in comparison with most legend systems that are not adequate for mapping comprehensively active and complex geomorphological systems such as debris flow catchments maps representing the various sediment storages and their relationships can be used for hydro geomorphological hazard mitigation

a major intraplate normal faulting earthquake the 1739 yinchuan event in northern china a large continental normal faulting earthquake occurred in the yinchuan graben in northern china on 3 january 1739 this event is of significant interest for two reasons first it has been suggested on the basis of historical records of shaking that this was a magnitude 8 0 event if this is true the 1739 earthquake would be one of the largest continental normal faulting earthquakes ever recorded and this should prompt us to consider the factors contributing to its unusual size second there has been some debate in the literature about the causative structure with at least three different faults posited as the seismogenic source we use five 14 c ages to date a series of scarps on the east helanshan fault which lies to the west of the graben and bracket the scarp formation to the last 350 years we use high resolution stereo imagery from the pleiades satellites to build a 1 to 2 m resolution dem of the fault and combine this with field observations to map the east helanshan rupture in detail we then construct a throw distribution determine the slip vector azimuth and reassess the earthquake magnitude using simple scaling relationships we conclude that the 1739 earthquake occurred on the east helanshan fault had a rupture length of approximately 87 km a maximum throw of 5 1 m and an average throw of 3 0 m yielding a best estimate magnitude in the range m w 7 1 to m w 7 6 we suggest that the previous magnitude estimates are biased by enhanced shaking of the sediments within the yinchuan graben

lithologic control of debris torrent occurrence a field based investigation into the frequency and magnitude of debris torrent systems reveals that lithology controls the spatial and temporal occurrence of debris torrents in the tsitika watershed vancouver island british columbia we identified 125 debris torrent systems in the watershed for half these basins we used dendrochronology historical air photographs and field surveys to estimate debris torrent frequency and magnitude for a 30 year period we find that the volcaniclastic half of the watershed contains more than twice as many debris torrent systems in which debris torrents occur over seven times more frequently and the deposits have a higher rate of delivery of sediment to the mainstem river than the intrusive half lithologic differences in weathering rates weathering product grain size and rock texture can explain the observed differences in debris torrent behaviour because debris torrents are the main sediment transport path from hilltop to valley bottom in the region these results confirm an important lithologic control on regional sediment transport while the exact numbers are uncertain we estimate that the sediment flux of volcaniclastic debris torrents in the watershed is five times higher than that of the intrusive debris torrents

conditions for generation of fire related debris flows capulin canyon new mexico comparisonoftheresponsesofthreedrainagebasinsburnedbythedomefireof1996innewmexicoisusedtoidentifythe hillslope channelandfirecharacteristicsthatindicateasusceptibilityspecificallytowildfire relateddebrisflow summer thunderstorms generated three distinct erosive responses from each of three basins the capulin canyon basin showed widespreaderosivesheetwashandrillingfromhillslopes andseverefloodingoccurredinthechannel thenorthtributary basin exhibited extensive erosion of the mineral soil to a depth of 5 cm and downslope movement of up to boulder sized material andatleastonedebrisflowoccurredinthechannel negligiblesurfacerunoffwasobservedinthesouthtributary basin thenegligiblesurfacerunoffobservedinthesouthtributarybasinisattributedtothelimitedextent andseverityof the fire in that basin the factors that best distinguish between debris flow producing and flood producing drainages are drainage basin morphology and lithology a rugged drainage basin morphology an average 12 per cent channel gradient andsteep roughhillslopescoupledwithcolluviumandsoilweatheredfromvolcaniclasticandvolcanicrockspromotedthe generation of debris flows a less rugged basin morphology an average gradient of 5 per cent and long smooth slopes mantled with pumice promoted flooding flood and debris flow responses were produced without the presence of waterrepellentsoils thecontinuityandseverityoftheburnmosaic theconditionoftheriparianvegetation theconditionofthe fibrous root mat accumulations of dry ravel and colluvial material in the channel and on hillslopes and past debris flow activity appearedtohavelittlebearingonthedistinctiveresponsesofthebasins publishedin2000byjohnwiley sons ltd

system morphological approach another look at morphology research and geomorphological mapping abstract a large number of studies require a clear and unambiguous morphological basis for over thirty years russian scientists have been applying a system morphological approach for the arctic and antarctic research ocean floor investigation for various infrastructure construction projects oil and gas sports etc in landscape and environmental studies this article is a review aimed to introduce this methodological approach to the international scientific community the details of the methods and techniques can be found in a series of earlier papers published in the russian language in 1987 2016 the proposed system morphological approach includes 1 partitioning of the earth surface i e precise identification of linear point and areal elements of topography considered as a two dimensional surface without any geological substance 2 further identification of larger formations geomorphological systems and regions 3 analysis of structural relations and symmetry of topography and 4 various dynamic litho and glaciodynamic tectonic etc interpretations of the observed morphology this method can be used to study the morphology of the surface topography as well as less accessible interfaces such as submarine and subglacial ones

frost weathering and rockwall erosion in the southeastern swiss alps long term 1994 2006 observations abstract rates and processes of frost weathering in the alps were investigated by visual observations of intensively shattered rocks continuous monitoring of frost wedging and rock temperatures in bedrock and measurements of rockfall activity rapid frost weathering of hard intact rocks occurs along lakes and streams where seasonal freezing promotes ice segregation in the rock otherwise rocks require pre existing weakness or a long exposure period for intensively shattered automated monitoring shows that crack opening occurs at three scales including small opening accompanying short term frost cycles slightly larger movements during seasonal freezing and occasional large opening originating from refreezing of snow melt water during seasonal thawing the opening events require at least partial water saturation in the crack the repetition of crack opening frost wedging results in permanent opening and finally debris dislocation debris collections below fractured rockwalls show that pebble falls occur at an average rate of about 0 1 mm a 1 with significant spatial and inter annual variations occasional large boulder falls significantly raise the rockwall erosion rates controlled by such factors as the joint distribution in the bedrock repetition of annual freeze thaw cycles and extraordinary summer thaw

elementary forms for land surface segmentation the theoretical basis of terrain analysis and geomorphological mapping abstract land surface morphology is fundamental to geomorphological mapping and many gis applications review and comparison of various approaches to segmentation of the land surface reveals common features and permits development of a broad theoretical basis for segmentation and for characterization of segments and their boundaries within the context of defining landform units that maximise internal homogeneity and external differences this paper introduces the concept of elementary forms segments units defined by constant values of fundamental morphometric properties and limited by discontinuities of the properties the basic system of form defining properties represents altitude and its derivatives constant values of which provide elementary forms with various types of homogeneity every geometric type of elementary form can be characterized by a defining function which is a specific case of the general polynomial fitted function various types of boundary discontinuity and their connections and transformations into other types of morphological unit boundaries are analysed the wealth of types of elementary forms and their boundaries is potentially unbounded and thus is sufficient to cover the real variety of landforms elementary forms in the basic set proposed here have clear potential for genetic and dynamic interpretation a brief worked example documents the possibility of analytical computation of various models of ideal elementary forms for particular segments of landform ideal elementary forms can be considered as attractors to which the affinity of surface segments can be measured by multivariate statistical methods the use of the concept of elementary forms in landscape segmentation is promising and it could be adapted for elementary segmentation of various other spatial fields

sediment concentration changes in runoff pathways from a forest road network and the resultant spatial pattern of catchment connectivity hydrological connectivity is a term often used to describe the internal linkages between runoff and sediment generation in upper parts of catchments and the receiving waters in this paper we identify two types of connectivity direct connectivity via new channels or gullies and diffuse connectivity as surface runoff reaches the stream network via overland flow pathways using a forest road network as an example of a landscape element with a high runoff source strength we demonstrate the spatial distribution of these two types of linkages in a 57 km 2 catchment in southeastern australia field surveys and empirical modelling indicate that direct connectivity occurs primarily due to gully development at road culverts where the average sediment transport distance is 89 m below the road outlet the majority of road outlets were characterised by dispersive flow pathways where the maximum potential sediment transport distance is measured as the available hillslope length below the road outlet this length has a mean value of 120 m for this catchment reductions in sediment concentration in runoff plumes from both pathways are modelled using an exponential decay function and data derived from large rainfall simulator experiments in the catchment the concept of the volume to breakthrough is used to model the potential delivery of runoff from dispersive pathways of the surveyed road drains n 218 only 11 are predicted to deliver runoff to a stream and the greatest contributor of runoff occurs at a stream crossing where a road segment discharges directly into the stream the methodology described here can be used to assess the spatial distribution and likely impact of dispersive and gullied pathways on in stream water quality 2005 elsevier b v all rights reserved

crustal deformation across and beyond the los angeles basin from geodetic measurements we combine 6 years of global positioning system gps data with 20 years of trilateration data and a century of triangulation taped distance and astronomic azimuth measurements to derive 66 interseismic station velocities in the greater los angeles region we interpolate the velocities to construct a regional strain rate map beyond the los angeles basin our results generally agree with the model proposed by the working group on california earthquake probabilities in 1995 important regional findings of this study are as follows 1 there is a significant n s convergence and e w extension about 0 22 and 0 17 0 05 strain yr respectively for the two components along the southern frontal fault system of the san gabriel mountains 2 the crustal deformation around the big bend of the san andreas fault saf cannot be explained solely by wrench style motion across the saf remaining motion could be part of a nw se extension which is the response to nfsw compression in the central transverse ranges region alternatively it could be caused by left lateral faulting on an oblique blind thrust beneath the san gabriel mountains 3 low strain rates axe found along the elsinore fault and newport inglewood 4 north south compression decreases from the raymond hill fault westward to the santa monica fault there is little east west extension along this fault system

ophiolite obduction in the quebec appalachians canada 40 ar 39 ar age constraints and evidence for syn tectonic erosion and sedimentation 1 2 3 detailed field work conducted in the dunnage zone of the quebec appalachians is herein combined with 40 ar 39 ar dating on a series of ophiolitic massifs crosscutting granites and associated metamorphic rocks occurring along the baie verte brompton line the taconian suture between laurentia and lower paleozoic peri laurentian oceanic terranes studied massifs are the lac brompton ophiolite and the riviere des plante ultramafic complex in southern quebec and the nadeau ophiolitic melange in the gaspe peninsula our work suggests that these massifs form remnants of eroded ophiolitic nappes which are unconformably overlain by the saint daniel and riviere port daniel melanges and correlate with the thetford mines and mont albert ophiolitic complexes our 40 ar 39 ar data and compiled regional age constraints indicate that ophiolite obduction was diachronous along the strike of the orogen the timing of obduction and melange formation varies according to the irregular geometry of the early paleozoic laurentian margin with earlier collision occurring along or at the margins of promontories obduction was initiated with the formation of infraophio litic metamorphic soles between ca 479 and 472 ma in southern quebec and the nadeau ophiolitic melange and pos sibly as late as ca 470 466 ma for the mont albert complex these sole rocks were later exhumed and translated onto the laurentian margin with the overlying ophiolites between 475 and 460 457 ma the uplifting and erosion of the orogenic wedge during the waning stages of obduction has resulted in the sedimentation of olistostromal melanges and onlapping flysch units above the ophiolitic nappes as well as foredeep flysch successions during the latest arenig to earliest caradoc