dynamic characteristics of a ground fissure site abstract the seismic response of an active ground fissure site was simulated by a shaking table test and a flac3d numerical simulation model coupled dynamic ground motions of earthquake and fissure activity were loaded on the model the characteristics of the fissure site that is the movement of the hidden fissure the uneven subsidence the acceleration and the lateral and vertical soil pressures were monitored and analyzed the following observations were made from this study the subsidence of the hanging wall was greater than that of the footwall the stretch caused by the uneven subsidence led to the appearance of the hidden fissure and the gradual widening of the fissure the peak acceleration in the hanging wall was larger than that of the footwall the pga increased with the height of the site the magnification coefficient of the pga had the largest value in the fissure and the magnification coefficient of the pga decreased with earthquake intensity the increments of lateral and vertical soil pressure also increased with earthquake intensity the vertical soil pressure at the location of the fissure was the largest these dynamic characteristics are vital to the safety design of underground structures in a fissure site

structural characterization of natural loess and remolded loess under triaxial tests this paper characterizes the microstructural evolution of saturated natural loess from a site in jingyang china during triaxial test along two stress paths for comparison the same soil in remolded state is also characterized mercury intrusion porosimetry mip scanning electron microscopy sem and environmental scanning electron microscopy esem were used for the microstructure investigation results show that the microstructure of natural loess is similar to that of remolded loess before the consolidated undrained cu triaxial tests including conventional triaxial compression ctc test and reduced triaxial compression rtc test on the contrary their microstructures are different after the tests deeper examination shows that loading led to a significant change of inter aggregate pores without modifying the intra aggregate pores in addition the volume of inter aggregate pores after the rtc test is greater than that after the ctc test under the same consolidation stress the microstructure features of natural and remolded loess after the tests are further used to analyze the macro mechanical behavior for better understanding the relationship between them the results show that it is the cementation bonds of which breakage is influenced by stress path and confining pressure that play important roles in the strength and deformation behavior

novel retrieval of volcanic so2 abundance from ultraviolet spectra projects i firb miur simulazione dei flussi lavici con gli automi cellulari n rbau01rmz4 002 ii sviluppo di sistemi di monitoraggio funded by dipartimento di protezione civile della regione sicilia ingv istituto nazionale di geofisica e vulcanologia sezione di catania italy iii eu funded sixth framework programme project 18354 novac iv leverhulme trust fellowship

geometry and distribution of regional joint sets in a non homogeneous stress field case study in the ebro basin spain abstract three regional joint sets striking n s e w and wnw ese affect the tertiary rocks of the central ebro basin from analysis of their chronological relationships and spatial distribution it is concluded that they correspond to two different tectonic events the n s set oldest and the e w set younger are present in the southern and central sectors while the wnw ese joint set predominates in the northern one the n s joints propagated in response to joint normal and fluid loads under an intraplate stress field with shmax oriented near n s related to forces caused by the convergence of africa iberia and europe and rifting at the valencia trough during the sedimentary infilling of the basin these joints are only present in the southern part of the area the e w joint set in the southern central sector records the same fracturing event as the wnw ese set does in the northern one its orientation was modified by the presence of the older n s set in the south which perturbed the regional stress field the younger wnw ese and e w joint sets are interpreted as unloading joints these propagated as a consequence of flexural uplift and exhumation related to isostatic rebound at the pyrenees and the ebro foreland basin a numerical approach is used to explain the inhomogeneous distribution of the n s joint set in terms of their absence being controlled by the depth of the water table at the time of their formation

geohazard map of cover collapse sinkholes in the tournaisis area southern belgium abstract this paper reports the methodology developed to draw up a geohazard map of cover collapse sinkhole occurrences in the tournaisis area in this area carboniferous limestones are overlain by a mesocenozoic cover mainly consisting of marls sand and clay the thickness of this cover ranges from a few meters to more than 100 m the surficial morphology of the area does not show any karstic evidence except for the occurrence of these collapses from a paleogeographical point of view a developed quaternary karst is not conceivable in the area recent works suggested that the collapses are set off from reactivated paleokarsts the paleokarsts studied in the area proved to be the result of a particular weathering of the limestone the organization of these paleokarsts seems very low and mainly guided by the limestone fracturing as for most induced sinkholes the reactivation of these paleokarsts is linked to the lowering of piezometric heads in most of the area a thick cover and intensive land use mask potential surface hints of the buried paleokarsts and of the fracturing of the bedrock aerial photographs and remote sensing techniques have therefore shown little results in delineating collapse hazard zones up to now the study of the surficial morphology is also of little help in order to draw up the geohazard map in such a difficult context hydrogeological data and geological mapping information could only be used these informations are based on a limited number of boreholes and piezometers and are thus only valid on a regional scale records of former collapses were also available these records were of great interest since sinkhole distribution is obviously clustered in the area bedrock roof and cover formation floor altitudes were digitized and adapted to produce digital thematic maps piezometric heads were imported from a calibrated groundwater model of the aquifer these data and a digital elevation model of the area were integrated into a geographical information system gis to produce a coherent 3 d description of the area on a regional scale parameters such as the dewatering of the limestone and the thickness of the cover formation where sinkholes occurred were then estimated density of former collapses was also computed this showed that zones of high sinkhole occurrence coincide with zones of heavy lowering of piezometric heads combining the density of former collapses with the dewatering of the limestone enabled us to delineate zones of low moderate and high collapse hazard

using multiple logistic regression and gis technology to predict landslide hazard in northeast kansas usa abstract landslides in the hilly terrain along the kansas and missouri rivers in northeastern kansas have caused millions of dollars in property damage during the last decade to address this problem a statistical method called multiple logistic regression has been used to create a landslide hazard map for atchison kansas and surrounding areas data included digitized geology slopes and landslides manipulated using arcview gis logistic regression relates predictor variables to the occurrence or nonoccurrence of landslides within geographic cells and uses the relationship to produce a map showing the probability of future landslides given local slopes and geologic units results indicated that slope is the most important variable for estimating landslide hazard in the study area geologic units consisting mostly of shale siltstone and sandstone were most susceptible to landslides soil type and aspect ratio were considered but excluded from the final analysis because these variables did not significantly add to the predictive power of the logistic regression soil types were highly correlated with the geologic units and no significant relationships existed between landslides and slope aspect

physical simulation of ground fissures triggered by underground fault activity abstract numerical modeling and physical simulation experiment are two important steps to investigate the stress and strain fields of overlying strata but sometimes it is very difficult to do the test of the physical experiment on a large scale soil sample due to the financial consideration and the available test site to investigate the features of the ground fissures prevailing in xi an city we undertook in this study a series of physical simulation tests on the large scale soil sample to analyze the stress and displacement fields caused by the underlying normal fault activity comparing with the fracturing modes of the ground fissures and the failure patterns of construction building it is evident that the experiment results coincide with the failure patterns of the building but not with the fracturing modes of the ground fissures which indicate that the ground fissures in xi an may be an old fracture surface having already spread to superficial layer covered by a very thin layer of loose soils and the groundwater over pumping is just a factor to make them exposed on the ground surface

surface and subsurface environmental degradation in the karst of apulia southern italy karst environments are highly vulnerable to a variety of degradation and pollution problems geology fractured carbonate rocks morphology presence of a network of cavities produced by karst processes and hydrogeology rapid concentrated flow through fractures and conduits of karst carbonates strongly favour the movement of contaminants towards the water table in particular poor quality of subsurface water can derive from polluting substances flowing at the surface and or by direct immission of liquid and solid waste into the water table through the systems of conduits and joints in the rock mass as a consequence water quality can deteriorate severely which implies very high economic and social costs in order to clean the polluted sites and restore the original situation in some cases such as when the original karst morphology is changed because of anthropogenic interventions the variations created in the landscape are not recoverable and a loss of sites of naturalistic interest has to be registered high vulnerability of a typical karst region of the mediterranean area is illustrated in this paper by describing some case studies from apulia southern italy the apulia region where karst processes have had a prominent role in the development of the present landscape is mostly underlain by intensely karstified limestone two cases of pollution due to solid waste into karst cavities grave di s leonardo in the gargano promontory and grave pelosello in the murge plateau landscape transformation in the minervino murge area and degradation of gravina monsignore a typical karst valley in southeastern murge are described in the paper in two out of four cases degradation of the sites was discovered thanks to activity from local speleologists who also acted as promoters for cleaning and safeguarding the polluted sites these examples underline well the mismanagement of karst territories in particular the common practice to dump refuse into sinkholes and caves the pollution of limestone aquifers and the effects that such pollution in karst areas might have in terms of the risk to public health

origin of ground fissures in the shanxi graben system northern china abstract since the 1950s hundreds of ground fissures have occurred in the shanxi graben system in northern china the fissures and related subsidence and differential settlement have caused and are causing substantial damage to homes agricultural land roads canals and other infrastructure although generally similar in appearance the fissures have different origins 1 some fissures coincide with northeast trending faults trenching shows that the fissures extend into the near surface faults increasing vertical offset clay beds and other stratigraphic markers at depth and therefore are probably the surface expression of fault movements 2 some fissures are demonstrably related to accelerated groundwater withdrawal this is particularly apparent in xi an city where groundwater levels have declined by about 15 m within 4 years 3 other fissures owe their origin to the well known process of soil collapse this is particularly common in the silty loessial sediments that occur within most of the valleys that comprise the shanxi graben system

characteristics and genesis mechanism of ground fissures in taiyuan basin northern china abstract since the 1980s ground fissures in the taiyuan basin have experienced blowouts resulting in a significant but hidden danger to cities in the basin this paper describes the plane and damage characteristics of the ground fissures based on the findings of field investigations and mapping most ground fissures in the basin were determined as linear with pinch out reappearances on the surface they were characterized by both horizontal tension with maximum widths and vertical offsets of up to 40 and 15 cm respectively the ground fissure strikes in the basin were observed to be consistent with those of nearby active faults and the long axis direction of the groundwater depression funnel the roads and houses that lie across the fissures were determined to be the most affected by ground fissure disasters in the basin the primary damage modes for the roads were vertical offset and surface collapse whereas buildings experienced foundation failure and tensile damage profiles obtained through geological drilling and trench exploration further revealed obvious tension and synsedimentary characteristics of the ground fissures correlated with existing faults correlation analysis shows that the formation of ground fissures in taiyuan basin is mainly related to faults and excessive groundwater extraction theoretical analysis revealed that the size and activity of ground fissures in the basin were positively correlated with four factors the dip of faults in an area regional tensile stress difference between the thicknesses of aquifers on either side of a fault and groundwater exploitation the significant increase in ground fissure activity since the 1980s mainly reflects uncontrolled groundwater discharge hence prevention of excessive groundwater exploitation in the basin would mitigate the destructive effects of the ground fissures

a geomorphological strategy for conducting environmental impact assessments in karst areas in their efforts to protect regional groundwater supplies governmental agencies are increasingly requiring studies of karst areas and their features in areas where tracer tests or geophysics are not required funded or otherwise feasible geomorphological methods remain as the primary tool for assessing karst this study proposes a geomorphologically based environmental impact assessment strategy for karst areas while it is supported with results from a study of the karstic edwards aquifer recharge zone on the camp bullis military training installation tx usa it is based on the study of several karst areas and is generalized to accommodate and be fine tuned for regional variations biological and other resource issues can also be assessed with this strategy the assessment identifies environmentally sensitive features and areas as is often required to meet regulatory directives in karst areas with relatively small features excavation is a key tool for accurate assessment although the results of this study will help to better manage karst areas proper management must be done on a regional scale the highly permeable nature of karst precludes adequate management solely on a feature by feature basis studies on the relationship of water quality to impervious cover show adverse environmental impacts significantly increase when impervious cover exceeds 15 of a surface watershed the camp bullis study finds similar impacts in its groundwater drainage basin supporting the argument of 15 impervious cover as a regionally effective means of also protecting karst aquifers when coupled with protection of critical areas identified by field surveys

development characteristics and mechanisms of damage causing urban ground fissures in datong city china abstract a set of widely developed ground fissures within the datong basin northern china have inflicted serious damage to farm fields roads houses and building foundations in datong city such emergence of large scale ground fissures is rare in urban areas the formation mechanisms of these features were therefore investigated in detail through surveying mapping trenching drilling and geophysical prospecting the 11 fissures in datong city are located on the hanging wall of the kouquan fault part of regional horst and graben terrain and run approximately parallel with a dominant strike of ne34 70 and a maximum length of 5 5 km these structures occur in clear zones with similar directions and lateral distributions on the surface they possess evident synsedimentary fault characteristics including y shaped trapezoidal and traction structures in their profiles the synergistic action of different tectonic factors and groundwater exploitation is responsible for fissure formation under the influences of regional tensile stress upper mantle uplift and fault block movement activity along local faults created hidden fracture systems within the hanging wall the over exploitation of groundwater in the region subsequently accelerated fracture growth and varying vertical compressibility of the strata on both sides of the local fault resulted in uneven subsidence on the surface generating tensile zones and promoting the appearance of fissures at the edges of settlement funnels

loess geohazards research in china advances and challenges for mega engineering projects 2019 loess is a meta stable cemented assemblage of mainly silt and clay sized particles of low plasticity when dry it behaves like a brittle material but when wetted up the fabric rapidly collapses unique geomorphological features include extensive surface erosion soil piping loess karst catastrophic landslides and widespread collapse hydro consolidation the chinese loess plateau is a more or less continuous drape of thick loess covering some 440 000 km2 it is one of china s regions that is most prone to geohazards this paper reviews advances in the research related to loess geohazards drawing particular attention to the need to apply research findings to recent very large mega construction projects in loess terrain such as the mountain excavation and city construction in yan an levelling 78 km2 for urban expansion the lanzhou new district creating 246 km2 of new level ground for construction and large engineered interventions in the landscape for gully control and land reclamation such as those in shaanxi and gansu generating agricultural land covering an area of some 8000 km2 these projects are in response to increasing pressures to facilitate expansion of urban centres their interconnecting infrastructures and their agricultural support systems it is argued that where proper application of scientific knowledge for engineering control e g densification drainage of these new landscapes is absent these projects could generate a substantial and costly geohazard legacy for future generations

subsidence rates and urban damages in alluvial dolines of the central ebro basin ne spain in the central ebro basin alluvial dolines develop on quaternary materials overlying neogene evaporites this process is very active analysing aerial photographs of different years important differences can be observed since the 1970s when the urbanisation of the area took place karst processes have damaged many buildings and infrastructures from the dates of construction and the repair of a number of buildings and pavements we calculate subsidence rates 12 120 mm year moreover we decided to monitor for around 4 years three dolines developed on urban areas to determine their subsidence behaviour a water level device with an error of 2 3 mm was utilised for this purpose the subsidence rates so obtained are 64 5 39 and 21 mm year which fit with the previous data from repaired zones

paleosubsidence and active subsidence due to evaporite dissolution in the zaragoza area huerva river valley ne spain processes spatial distribution and protection measures for transport routes abstract the lowest 17 km long reach of the huerva river valley down to its confluence with the ebro river in zaragoza city flows across salt bearing evaporites of the ebro tertiary basin ne spain upstream the horizontally lying miocene evaporites are interfingered with non soluble distal alluvial fan facies shales and sandstones the proportion of soluble facies in the huerva river valley increases in a downstream direction towards the basin depocenter on the basis of the type and magnitude of the paleosubsidence features the valley has been divided into four reaches along reach i undeformed terrace deposits less than 4 m thick rest on insoluble detrital bedrock in reaches ii and iii dissolution at the alluvium bedrock boundary has generated local thickening deformation and paleocollapse structures which only affect the alluvial mantle in reach iv terrace deposits thicken to over 60 m resulting from a large scale synsedimentary subsidence in this sector subsidence locally affects to both the alluvium and the underlying bedrock this indicates that dissolution acts at the rockhead beneath the alluvial cover alluvial karst and within the evaporitic substratum interstratal karst the development of an intraevaporitic karst in reach iv is attributed to gypsum and salt dissolution irregular terrace gravel bodies gravel pockets embedded in a fine grained matrix associated with paleocollapse structures have been interpreted as liquefaction fluidization structures resulting from ground acceleration and suction induced by catastrophic collapses subsidence is currently active in the region affecting areas with a thin alluvial cover in reaches iii and iv the low subsidence activity in most of zaragoza city is explained by the presence of thickened around 50 m and indurated alluvial deposits in the surrounding area numerous buildings in cadrete and santa fe villages have been severely damaged by subsidence natural and human induced subsidence favours the development of slope movements in the gypsum scarp overlooking cadrete village several transport routes including the imperial canal irrigation canal and the recently completed madrid barcelona high speed railway are affected by human induced sinkholes the paleocollapse structures exposed in the trenches of this railway and a ring road under construction point to hazardous locations underlain by cavities and collapse structures where special protection measures should be applied rigid structures are recommended beneath the high speed railway with sufficient strength to span the larger sinkholes with no deformation electronic monitoring devices linked to a warning system can detect subtle subsidence induced deformations in carriageways or railways this research demonstrates that the study of the paleokarst helps to understand the processes involved in the present day subsidence phenomena and their general spatial distribution

distribution and mechanism of the ground fissures in wei river basin the origin of the silk road wei river basin wrb is the origin of the ancient and new silk road and it is located in southern fen wei graben system china since 1950s hundreds of ground fissures have formed in this affluent basin and these ground fissures have become the main geohazard in wrb this paper used a series of geological investigations such as site investigation trench excavation geological drilling and geophysical survey to understand the distribution and mechanism of formation of the ground fissures in wrb the results are 1 212 ground fissures in wrb were located in xi an xianyang weinan city and they have clear orientations mainly distributed from nee to sww nw to se and e to w moreover the ground fissures are accompanied by active faults along the same directions 2 ground fissures in wrb can be divided into two types some ground fissures display obvious horizontal and vertical separations on the earth surface whereas others only display obvious horizontal separations on the earth surface 3 ground fissures in wrb are triggered by four factors viz basin structure active fault human activities and loess erosion 4 the mechanism for the formation of ground fissures has also been proposed tectonic faulting is the fundamental cause of ground fissures in the wei river basin and imbalances in the man land caused by human actives accelerated the ground fissures activities 5 many effective measures have also been proposed to mitigate the hazards of ground fissures in wrb such as planning engineering measures controlling the exploitation of groundwater and monitoring this research will be helpful in safeguarding the sustainable development of the silk road economic belt

subsidence hazards due to evaporite dissolution in the united states evaporites including gypsum or anhydrite and salt are the most soluble of common rocks they are dissolved readily to form the same type of karst features that typically are found in limestones and dolomites and their dissolution can locally result in major subsidence structures the four basic requirements for evaporite dissolution to occur are 1 a deposit of gypsum or salt 2 water unsaturated with caso4 or nacl 3 an outlet for escape of dissolving water and 4 energy to cause water to flow through the system evaporites are present in 32 of the 48 contiguous states of the united states and they underlie about 35 40 of the land area karst is known at least locally and sometimes quite extensively in almost all areas underlain by evaporites and some of these karst features involve significant subsidence the most widespread and pronounced examples of both gypsum and salt karst and subsidence are in the permian basin of the southwestern united states but many other areas also are significant human activities have caused some evaporite subsidence development primarily in salt deposits boreholes may enable either intentionally or inadvertently unsaturated water to flow through or against salt deposits thus allowing development of small to large dissolution cavities if the dissolution cavity is large enough and shallow enough successive roof failures above the cavity can cause land subsidence or catastrophic collapse

evolution and origin of the ground fissures in xian china large scale extraction of ground water in xian has resulted in significant drawdown of the phreatic surface and in land subsidence across this ancient capital of china it has also triggered the rejuvenation of the normal faults in the upper portions of the quaternary deposits underlying the city leading to surface rupturing and the development of ground fissure zones across the city these ground fissure zones are structurally controlled in the sense that they are directly linked to the normal faults in the quaternary deposits all trending in an east northeasterly direction in essence they are the surface expressions of the deeper faults under current drawdown conditions the ground fissures have resulted in extensive property damage along their paths of propagation this paper describes their occurrence their possible causative mechanism and the resultant damage of necessity xian will still be dependent on ground water supply to a large extent in the years ahead however ground water extraction will have to be managed in an environmentally sustainable manner in order to minimize the geological hazards associated with the ground fissures

karst in gypsum and its environmental impact on the middle ebro basin spain the middle ebro basin in characterised by strong evaporitic profiles from the miocene period and in which gypsum formations are predominant these groups of easy solubility produce in many areas typically karstic landforms although there are certain features specific to them the generated landforms appear on the surface as different morphological types of doline which very often develop on the alluvium deposited by the river ebro and its affluents on the agricultural land of the penaflor villamayor area the functional character of karst causes collapse dolines to appear after heavy storms and these are constantly filled in by farmers motorways and roads that cross these areas as also the industrial estates existing on the outskirts of zaragoza are affected by dissolution processes that bring about continual collapses the infiltration of water from unlined canals causes the generation of numerous dolines along canal banks

the origin and impact of the shizhuang ground fissure yingxian area datong basin china abstract the datong basin is part of the regionally extensive fenwei graben system a major tectonic zone impacted by active tectonics and the resulting damage to life and infrastructure the basin also contains the shizhuang ground fissure system in this study the likely origin surface extent and fissure subsurface characteristics are explored by traditional methods surveying mapping trenching drilling and seismic exploration the shizhuang ground fissure is located at the intersection of the xiaoshikou fault and the southern liuleng margin fault in yingxian county it has a length of 2 1 km excellent continuity and semi elliptical surface morphology the dislocation of strata induced by the fissure increases significantly as the depth increases the strata bend downward and form typical traction structures near the fissure plane indicating that the fissure has prominent synsedimentary fault characteristics the fissure causes serious damage to houses farmlands roads and public facilities featuring large tensile cracks and vertical dislocations the resulting data and interpretations indicate that 1 the ground fissures connect to two major subsurface active faults which lay the tectonic foundation for the fissure 2 accelerated groundwater extraction has reactivated the underlying faults and exacerbated fissure development and 3 mitigation is best achieved by cessation of excessive groundwater pumping appropriate engineering design and local avoidance for placement of critical structures this paper provides a heretofore generally unknown example promotes research on the mechanisms of fissures and has guiding significance for disaster prevention and reduction in this area

earth fissures developed within collapsible loess area caused by groundwater uplift in weihe watershed northwestern china abstract earth fissures are geological hazards that frequently occur all over the world and greatly threaten the safety of people s property and lives this paper reports a case from a typical agricultural town in the weihe watershed northwest nw of china dali which has been severely affected from earth fissures in recent years a comprehensive survey was made on the geometric characteristics of the earth fissures developed in the study area through field investigations trial trenches boreholes exploratory wells and laboratory tests the study indicates that fourteen nearly parallel fissures have developed in the area with a fissure to fissure space of 140 350 m and a maximum length of any of the given fissures of 500 m the underlying faults loess joints and the quaternary unconsolidated and collapsible sedimentary loess provide a favorable geological condition for the occurrence of the earth fissures from 2003 to 2012 the groundwater level in the area rose about three meters due to agricultural irrigation and leakage of a water diversion canal collapsible deformation occurred in the loess while seepage erosion expanded the original joints in the soil the earth fissures occurred resulting from multiple geological environmental forces and human activities

ifit a simple method for measuring volcanic so2 without a measured fraunhofer reference spectrum abstract accurate quantification of the emission rate of sulphur dioxide so2 from volcanoes provides both insights into magmatic processes and a powerful monitoring tool for hazard mitigation the primary method for measuring magmatic so2 is differential optical absorption spectroscopy doas of uv scattered sunlight spectra in which a reference spectrum taken outside the plume is used to quantify the so2 slant column density inside the plume this can lead to problems if the reference spectrum is contaminated with so2 as this will result in a systematic underestimation of the retrieved so2 slant column density and therefore emission rate we present a new analysis method named ifit which retrieves the so2 slant column density from uv spectra by directly fitting the measured intensity spectrum at high spectral resolution 0 01 nm using a literature solar reference spectrum and measured instrument characteristics this eliminates the requirement for a measured reference spectrum providing a point and shoot method for quantifying so2 slant column densities we show that ifit retrieves correct so2 slant column densities in a series of test cases finding agreement with existing methods we propose that ifit is suitable for both traverse measurements and permanent scanning stations and could be integrated into volcano monitoring networks at observatories finally we provide an open source software implementation of ifit with a user friendly graphical interface to allow users to easily utilise ifit

overview of ground fissure research in china ground fissures in china have garnered increasing international attention in recent years due to their areal extensiveness large scale and high hazard potential these fissures especially those in the fen wei basin and north china plain severely restrict planning and construction in big cities threaten the operation of underground and above ground railways and cause serious economic loss recent research shows that ground fissures in china occur mainly in sedimentary basins and develop along active faults and at the edges of groundwater cones of depression most of these fissures are caused by the combined action of tectonic stress and hydrodynamic force effective ground fissure disaster reduction technologies are developed and they include pumping control reasonable avoidance adaption to deformation and local strengthening this paper provides an overview on ground fissure studies in china and demonstrates how research results can serve economic development and geohazard mitigation

characteristics of land subsidence earth fissures and related disaster chain effects with respect to urban hazards in xi an china the ancient capital of xi an is a typical city in china with a shortage of water resources with an urban population of 7 million its domestic and industrial use of water depends almost entirely on groundwater large scale long term extraction of groundwater has caused severe land subsidence and triggered the reactivation of active normal faults in the quaternary under consolidated sediments underlying the city this has further led to ground ruptures that have gradually evolved into earth fissure zones during this process there has been a close spatiotemporal relationship between land subsidence and the formation of earth fissures from field monitoring data the subsidence bowls are typically located in loess depressions between earth fissure zones within structural blocks of sediment cut by active quaternary faults and preexisting fault planes the subsidence bowls are generally elliptical in shape with the long axes consistent with the preferred orientation of the earth fissures the underlying quaternary active faults and preexisting fault planes predispose the intervening sediment blocks to formation of earth fissures and intense groundwater extraction has led to accelerated subsidence and earth fissuring during the past 50 years mining groundwater land subsidence and earth fissures occur in a sequence and constitute a disaster chain with respect to urban hazards in xi an thus it is important to understand the relationships between these events this paper summarizes the characteristics of land subsidence and earth fissures in xi an and discusses the chain of relationships that connects them

on the use of different spectral windows in doas evaluations effects on the estimation of so2 emission rate and mixing ratios during strong emission of popocatepetl volcano abstract reported so2 emission values at strongly degassing volcanoes might be underestimated scanning spectroscopic instruments are widely used at volcanoes to quantify so2 emission rates and occasionally molar ratios between so2 and other gases such as bro frequently differential optical absorption spectroscopy is applied to evaluate spectra in the ultraviolet range if radiative transfer effects are not considered in the evaluations the retrieved column densities may vary depending on which spectral window is used we compare the use of different windows for data collected at popocatepetl volcano during strong degassing periods when high column densities lead to especially high dependence on the applied evaluation window we propose the use of three different windows 310 322 nm 314 7 326 7 nm and 322 334 nm and a simple algorithm to choose the most accurate column density from them the so2 evaluation using proper spectral windows would allow a more realistic estimation of the so2 emission rates

centrifuge modeling of reverse fault rupture propagation through single layered and stratified soil abstract many buildings have been built over active faults surface faulting as a main effect of earthquakes can cause damage such buildings properties of material over bedrock affect the pattern of rupture propagation through deposits and the width of the rupture zone on ground surface several researchers have primarily studied fault rupture propagation patterns on single layered granular soil however natural geologic deposits are rarely homogeneous and uniform but mostly consist of different layers in this study centrifuge model tests were conducted to investigate the patterns of reverse fault rupture propagation through single and double layered soil stratum it was observed that the soil type and sequence of layers affected the fault rupture propagation pattern as well as the surface rupture zone the results show that the width of deformation zone tends to decrease in stiffer soil in compare to softer soil these findings may help to produce a framework for predicting the occurrence and geometry of surface fault rupture zone that can help us to define a setback zone which is a major concern in building codes

authors reply to discussion by i yilmaz on development and morphometry of sinkholes in coastal plains of apulia southern italy preliminary sinkhole susceptibility assessment engineering geology 99 2008 198 209 the authors would like to express their thanks tothe discusser isikyilmaz for his interest in our paper and the related comments in thisreplywepresentourexplanations hopingthattheywillhelptoclarifythe points raised by the discusser asapremise wehavetopointoutthatapulia aregionwherekarstisamongthemainprocessesactinginevolutionofthelandscape bothat the surface and underground dedicates institutionally very scarceattention to karst hazards which results in high degradation of theterritory withadverseconsequencesonthequalityofkarstwatersandloss of peculiar karst landscapes parise and pascali 2003 recentstudies dedicated to evaluating the degree of disturbance to the karstenvironment by applying a speci cally created karst disturbanceindex van beynen and townsend 2005 demonstrate that apuliankarstismoderatelytohighlydisturbed caloandparise 2006 northetal 2008 this is an extremely severe situation for a karst territory since karst is known as one of the most fragile environment in theworld extremely vulnerable to pollution and susceptible to a numberof geo hazards waltham et al 2005 fordand williams 2007 pariseand gunn 2007 as regards to sinkholes apulia presents all thetypologies of sinkholes well distributed in the different parts of theregion delle rose et al 2004 in part also related to anthropogenicactivities astherecentcaseregisteredinapril2007atgallipoli whereaseveralmetersdeepsinkholeopenedinafewhoursinthetown dueto presence of ancient underground quarries luckily the collapseinterested a street crossing only marginally affecting buildings andnobody was injured notwithstanding this situation there is no study at the regionallevel aimed at recognizing the presence of sinkholes and the hazardthey pose to the human society only recently in 2006 as we havereported in the conclusions of our article the apulian regional basinauthority issued an act dictating rules to be followed in areas exposedto underground cavities and or sinkhole hazard the rst aim of our work was therefore to raise the attention onthis very subtle hazard at the same time performing a preliminaryattempt we will return to this further on in developing a sinkholesusceptibility map we agree with the assumption that in the attempt to identifycollapse susceptibleareas themainfactorsleadingtocollapsehavetobe analyzed rst upchurch and little eld 1988 benson et al 2003 hubbard 2003 brinkmannetal 2008 sinceitisexpectedthatfuturecollapses will occur under the same conditions as past collapses actually our study started from characterization of the main factorsinvolved and the deriving results were presented in section 4 morphometry there in particular size depth slope distance from

characteristics and mechanisms for origin of earth fissures in fenwei basin china abstract the most serious earth fissure disasters in china occur in the fenwei basin since the late 1950s earth fissure disasters have widely occurred in the weihe yuncheng linfen taiyuan and datong sub basins in the fenwei basin and such disaster has increased progressively in recent years the current paper summarizes the characteristics of earth fissures in the fenwei basin earth fissures usually occur in an extensional faulted basin along an active fault zone and within an area of land subsidence earth fissures often have a similar trend with many branches that intermittently appear along their strike the main and secondary earth fissures at a shallow depth form rupture belts of different widths but they merge into a single shear belt and stay connected with the underlying active fault the throw of two blocks increases with depth along a sedimentary fault earth fissures usually show the characteristic of three dimensional movement vertical dislocation is the primary aspect of earth fissure movement the horizontal tension is smaller and the horizontal twist is the smallest which is consistent with the movement pattern of underlying active faults earth fissures have exhibited activity three or four times since the late pleistocene in the past half century earth fissures formed during four or five periods of peak activity were influenced strongly by groundwater fluctuation our research also indicates that cluster formation of earth fissures is polygenetic and results from a combination of tectonic and human activities earth fissures are driven by deep tectonic motions beneath the basin and are controlled by the local tectonic stress of the local fault zones one of the most important factors contributing to earth fissure formation is groundwater overexploitation this paper provides a scientific basis for proposed administrative means mitigation measures and engineering solutions in the field of engineering geology

morphometric analysis of sinkholes in a karst coastal area of southern apulia italy salento the southern portion of apulia region se italy is a narrow and elongated peninsula in carbonate rocks with prevailing low coastlines locally interrupted by high rock cliffs the long stretches of low coasts are marked by typical karst landforms consisting of collapse sinkholes as observed in many other karst coastal settings worldwide development of sinkholes may be particularly severe along the coasts where both natural and anthropogenic processes contribute to accelerate the dissolution of carbonate rocks and subsidence processes even influencing the coastline evolution following a previous study where the main features of sinkholes at torre castiglione taranto province were investigated and described and a preliminary susceptibility map produced at the light of updated data and elaborations in the present paper we perform a detailed morphometric analysis on the sample of identified sinkholes the main morphometric parameters generally used for sinkhole characterization have been considered in this study shape of the sinkhole azimuth and length of maximum and minimum axes depth elongation ratio and distance from the shorelines each of them is described both as individual parameter and in conjunction with the others in the attempt to identify the main factors controlling development of sinkholes in the area and their evolution as well with regard to this latter aspect beside simple morphometry of the sample of sinkholes at torre castiglione we also focused our attention on the likely relationships existing between distribution and shape of the sinkholes and the tectonic discontinuities to investigate the matter a three stage analysis has been carried out in this study by means of field measurements of the fractures bounding the sinkholes field measurement of the long axes azimuth of the elongated sinkholes comparison of the previously described sets with the strikes of the main regional geological structures the obtained results show in addition to the coincidence of the main regional discontinuity systems with the major axis of elongated sinkholes a clear control exerted by development and evolution of the sinkholes on the formation of coastal inlets and bays eventually the approach here presented may be applied in other karst coastal sinkhole prone areas to gain new knowledge on the genesis and evolution of coastal sinkholes and to properly evaluate the hazard they pose to the anthropogenic environment

karst database implementation in minnesota analysis of sinkhole distribution this paper presents the overall sinkhole distributions and conducts hypothesis tests of sinkhole distributions and sinkhole formation using data stored in the karst feature database kfd of minnesota nearest neighbor analysis nna was extended to include different orders of nna different scales of concentrated zones of sinkholes and directions to the nearest sinkholes the statistical results along with the sinkhole density distribution indicate that sinkholes tend to form in highly concentrated zones instead of scattered individuals the pattern changes from clustered to random to regular as the scale of the analysis decreases from 10 100 km2 to 5 30 km2 to 2 10 km2 hypotheses that may explain this phenomenon are 1 areas in the highly concentrated zones of sinkholes have similar geologic and topographical settings that favor sinkhole formation 2 existing sinkholes change the hydraulic gradient in the surrounding area and increase the solution and erosional processes that eventually form more new sinkholes

doline probability map using logistic regression and gis technology in the central ebro basin spain in the surroundings of zaragoza karstification processes are especially intense in covered karst areas where fluvial terraces lie directly on tertiary evaporites since the beginning of quaternary these processes have lead to the development of collapse and subsidence dolines with a wide range of sizes which have significant economic impacts to reduce economic impact and increase safety a regional analysis of this phenomenon is needed for spatial management therefore a probability map of dolines was developed using logistic regression and geographic information system gis techniques this paper covers the selection of input data manipulation of data using the gis technology and the use of logistic regression to generate a doline probability map the primary variable in the doline development in this area is geomorphology represented by the location of endorheic areas and different terrace levels secondary variables are the presence of irrigation and the water table gradient

radiative transfer corrections for accurate spectroscopic measurements of volcanic gas emissions there is widespread use of passive remote sensing techniques to quantify trace gas column densities in volcanic plumes utilizing scattered sunlight as a light source examples include passive doas cospec and the so2 camera in order to calculate trace gas concentrations or volcanic emission fluxes knowledge about the optical path through the plume is necessary in the past a straight photon path through the plume has always been assumed although it was known that this is not always true here we present the results of model studies conducted specifically to quantify the effects of realistic radiative transfer in and around volcanic plumes on ground based remote sensing measurements of so2 the results show that measurements conducted without additional information on average photon paths can be inaccurate under certain conditions with possible errors spanning more than an order of magnitude both over and underestimation of the true column density can occur actual errors depend on parameters such as distance between instrument and plume plume so2 concentration plume aerosol load as well as aerosol conditions in the ambient atmosphere as an example a measurement conducted with an so2 camera is discussed the results of which can only be correctly interpreted if realistic radiative transfer is considered finally a method is presented which for the first time allows the retrieval of actual average photon paths in spectroscopic i e doas measurements of adequate resolution by allowing for a wavelength dependent column density during the evaluation of doas measurements we show how radiative transfer effects can be corrected using information inherently available in the measured spectra thus greatly enhancing the accuracy of doas measurements of volcanic emissions

sinkhole distribution in a rapidly developing urban environment hillsborough county tampa bay area florida sinkhole formation in florida is a common event the florida karst plain is significantly altered by human development and sinkholes cause considerable property damage throughout much of the state we present in this paper a morphometric analysis of karst depressions in the tampa bay area and the relation with the known distribution of sinkholes we selected the tampa bay area because it is particularly susceptible to the evolution of karst depressions in relation with development of the built up environment karst depressions were mapped from the 1 24 000 usgs topographic maps and a morphometric analysis was performed by using parameters such as shape circularity index perimeter area length width and orientation maps showing the distribution of depression density and the sectors with greatest areas of karst depression were produced using a gis these results were compared with data compiled from the database of sinkhole occurrences in florida maintained by the florida geological survey our analysis demonstrates that the distribution of new sinkhole occurrences differs from the distribution of existing sinkholes indicating that there are processes acting today that are influencing karst landscape formation that are different from those acting in the past

development and validation of sinkhole susceptibility models in mantled karst settings a case study from the ebro valley evaporite karst ne spain abstract a preliminary sinkhole susceptibility analysis has been carried out in a stretch 50 km 2 in area of the ebro valley alluvial evaporite karst ne spain a spatial database consisting of a sinkhole layer and 27 thematic layers related to causal factors was constructed and implemented in a gis three types of sinkholes were differentiated on the basis of their markedly different morphometry and geomorphic distribution large subsidence depressions 24 large collapse sinkholes 23 and small cover collapse sinkholes 447 the susceptibility models were produced analysing the statistical relationships between the mapped sinkholes and a set of conditioning factors using the favourability functions approach the statistical analyses indicate that the best models are obtained with 6 conditioning factors out of the 27 available ones and that different factors and processes are involved in the generation of each type of sinkhole the validation of two models by means of a random split strategy shows that reasonably good predictions on the spatial distribution of future dolines may be produced with this approach around 75 of the sinkholes of the validation sample occur on the 10 of the pixels with the highest susceptibility and about 45 of the area can be considered as safe

characteristics and mechanism of sanyuan ground fissures in the weihe basin china abstract shuanghuaishu ground fissures in sanyuan county ones of over 200 ground fissures developed in the weihe basin are well known for their sudden occurrence which often cause severe damage to the infrastructures after heavy rainfall in order to reveal the origin of their formation the geological background developmental characteristics and genetic mode of the shuanghuaishu ground fissures were investigated in details by surveying mapping trenching geological drilling geophysical prospecting and field water immersion the fissures are almost parallel with a ne50 ne65 strike and the obvious linear length is 800 m these characteristics are well consistent with the secondary faults of the liquan pucheng heyang fault the fissures cause damage to buildings and farmlands in the form of a horizontal tensile crack and subsidence the deeper the stratum is the bigger fault displacement of the stratum it will be so these fissures possess the characteristics of synsedimentary faults regarding their genesis the fissures were generated under the coupling action of multiple factors the regional extension caused secondary faults of the liquan pucheng heyang fault to slip resulting in a fracture system in the surface strata during the period of heavy rainfall large volumes of water seeped into these hidden fissures causing a strong erosion and washout effect on the soil filled in the fissures this process promoted the formation of the current ground fissures

the application of gis based logistic regression for landslide susceptibility mapping in the kakuda yahiko mountains central japan as a first step forward in regional hazard management multivariate statistical analysis in the form of logistic regression was used to produce a landslide susceptibility map in the kakuda yahiko mountains of central japan there are different methods to prepare landslide susceptibility maps the use of logistic regression in this study stemmed not only from the fact that this approach relaxes the strict assumptions required by other multivariate statistical methods but also to demonstrate that it can be combined with bivariate statistical analyses bsa to simplify the interpretation of the model obtained at the end in susceptibility mapping the use of logistic regression is to find the best fitting function to describe the relationship between the presence or absence of landslides dependent variable and a set of independent parameters such as slope angle and lithology here an inventory map of 87 landslides was used to produce a dependent variable which takes a value of 0 for the absence and 1 for the presence of slope failures lithology bed rock slope relationship lineaments slope gradient aspect elevation and road network were taken as independent parameters the effect of each parameter on landslide occurrence was assessed from the corresponding coefficient that appears in the logistic regression function the interpretations of the coefficients showed that road network plays a major role in determining landslide occurrence and distribution among the geomorphological parameters aspect and slope gradient have a more significant contribution than elevation although field observations showed that the latter is a good estimator of the approximate location of slope cuts using a predicted map of probability the study area was classified into five categories of landslide susceptibility extremely low very low low medium and high the medium and high susceptibility zones make up 8 87 of the total study area and involve mid altitude slopes in the eastern part of kakuda mountain and the central and southern parts of yahiko mountain

analysis and comparison of two types of ground fissures in dali county in the weihe basin china dali county is located in the eastern weihe basin where frequent ground fissure disasters occur dali ground fissures are macroscopically part of the ground fissure group in the weihe basin and have caused serious damage to infrastructure and agricultural production in this area in this paper 25 ground fissures in dali county are identified through investigation and two typical ground fissures in fengcun and weizhuang are selected for research through field investigation trench excavation geophysical exploration soil water content tests and collapsibility coefficient tests the basic features shallow structural characteristics deep structural characteristics and genetic mechanisms of the two ground fissures are revealed the strike of the fengcun ground fissure is 45 almost parallel to the shuangquan linyi fault the length is 2 km and the profile is ladder like and extends deep with synsedimentary characteristics the weizhuang ground fissures are circular in plan view with a length of 315 m and trumpet shaped in profile they disappear in the paleosol layer the mechanism of the fengcun ground fissure is related to basin extension and fault activity the ground fissures are the surface reflections of deep faults the mechanism of the weizhuang ground fissures is related to loess collapsibility and seepage the malan loess has differential settlement in collapsible and noncollapsible areas and ground fissures are the boundary line for differential settlement of loess finally based on the genetic mechanisms of ground fissures dali ground fissures can be divided into two types tectonic and nontectonic

subsidence hazard avoidance based on geomorphological mapping in the ebro river valley mantled evaporite karst terrain ne spain in the valley of the ebro river to the southeast of the city of zaragoza ne spain the dissolution of evaporite sediments gypsum halite and na sulphates which underlie alluvial deposits gives rise to numerous sinkholes these sinkholes are a potential hazard to human safety particularly where they develop in a catastrophic way even slow developing sinkholes are problematic as they damage urban and agricultural infrastructure necessitating costly repairs and vigilant maintenance to assist in developing avoidance strategies for these hazards the factors controlling sinkhole occurrence have been assessed using geomorphological maps produced from aerial photographs for 1956 and 1981 important controls on sinkhole development are found to include underlying geological structure manifest in preferred orientations of sinkholes on the azimuths n130 150e and n30 40e and the presence of glauberite in the groundwater flow path which apparently promotes accelerated gypsum dissolution perhaps surprisingly alluvium thickness does not appear to significantly correlate with the density of sinkholes on the floodplain in this area the maps for 1956 and 1981 reveal that both human activity and natural processes can serve to obscure the true density of sinkhole development for instance a large number of sinkholes which were conspicuous in 1956 have since been back filled by farmers in the most fluvially active zone of the ebro valley the meander belt the relatively low density of sinkholes compared with adjoining zones suggests that subsidence is being masked by morpho sedimentary dynamic processes aggradation and erosion careful geomorphological mapping for different time periods yields a much more accurate impression of the frequency of sinkhole development than would be gained from surveying currently visible sinkholes in the area of interest

characteristics and mechanism of the longyao ground fissure on north china plain china abstract among more than 1000 ground fissures developed over the past 30 years having induced severe geohazards in the north china plain the longyao ground fissure in hebei province is famous for its longest length and causing the worst damage and widest influence in this region in order to reveal the origin of its formation the geological background developmental characteristics and genetic mode of the longyao ground fissure were investigated in detail by geological surveys measurements trenching drilling and seismic exploration this fissure has a total length of 39 km and is characterized by normal fault extension left lateral slip and dominant along polyline distribution these characteristics are well consistent with its underlying fault the nei jv fault the fissure causes the damage to buildings structures along a polyline and in the form of a horizontal tensile crack subsidence and shear failure according to the trenching drilling and shallow seismic profiling this fissure possesses the characteristics of synsedimentary faults reflecting the historical stages of fissure activities regarding its genesis this fissure was generated under the coupling action of multiple factors which took shape after the earthquake and was enlarged under the action of groundwater pumping the regional extension first caused a fracture system in the surface strata and then the action of seismic activities started to control the fracture and finally the pumping action of excessive groundwater and other influential factors promoted the formation of the current ground fissure

geomorphology of the tertiary gypsum formations in the ebro depression spain abstract this paper reviews the current knowledge of the mainly karstic geomorphological features developed in the evaporitic formations of the ebro depression northern spain special emphasis is given to the recently published and unpublished scientific advances the gypsum formations of tertiary age have an extensive outcrop area within the ebro depression here their morphogenesis is controlled mainly by processes of surface and subsurface dissolution acting on the gypsum outstanding landforms in the gypsum terrain include saline lakes developed in flat bottom dolines saladas other characteristic morphologies include karren and gypsum domes which occur on a decimetre scale where the gypsum is covered by quaternary alluvial deposits the karstification processes are especially intense and cause subsidence phenomena karstic subsidence affects stream terraces mantled pediments and infilled valleys which in the region are called vales dissolution induced synsedimentary subsidence has produced interesting geological features which include significant thickening and deformation of the alluvial deposits in contrast to the rapid removal of gypsum by dissolution the amount of gypsum removed by erosion is low water erosion studies carried out on gypsiferous slopes of the ebro depression indicate that the sediment yield ranges from 0 59 to 7 82 t ha year this low yield results from the high infiltration capacity of the soils subsidence caused by gypsum dissolution has important socio economic consequences in the ebro depression the active alluvial karstification of the gypsum causes numerous sinkholes that are harmful to linear structures roads railway lines irrigation channels buildings and agricultural land unforeseen catastrophic subsidence also puts human lives at risk the benefits of such terrains include thickened alluvial deposits which act as valuable water reservoirs and which form excellent sources of aggregates fluvial valleys in this gypsiferous terrain commonly show an asymmetrical geometry with prominent gypsum scarps at one side these gypsum scarps are affected by numerous landslides these slope movements are hazardous may dam rivers and cause flooding of the alluvial plains

karst unit mapping using geographic information system technology mower county minnesota usa mower county is in southeastern minnesota in an area underlain by sedimentary bedrock these rocks are karsted middle devonian and middle ordovician limestone and dolomite the karst features of the county were inventoried these features include sinkholes disappearing streams caves dry valleys and springs previous karst mapping efforts for other counties in minnesota have produced sinkhole probability maps and a springshed map in mower county we have developed a new type of karst map using a geographic information system gis to produce a karst unit map karst units are discrete three dimensional bodies in which solution of the bedrock has resulted in the integration of surface water and groundwater the field mapping and hydrologic investigations were done with conventional methods the karst unit delineation was done using gis technology which allowed us to examine the county s karst using two dimensional and three dimensional views many different overlays of the karst elements were combined to better understand the landscape dynamics ultimately it was the overlay of the karst features hydrologic information and depth to bedrock mapping on a shaded relief landscape morphology map which allowed us to best delineate the individual karst units

logistic analysis of channel pattern thresholds meandering braiding and incising a large and geographically diverse data set consisting of meandering braiding incising and post incision equilibrium streams was used in conjunction with logistic regression analysis to develop a probabilistic approach to predicting thresholds of channel pattern and instability an energy based index was developed for estimating the risk of channel instability associated with specific stream power relative to sedimentary characteristics the strong significance of the 74 statistical models examined suggests that logistic regression analysis is an appropriate and effective technique for associating basic hydraulic data with various channel forms the probabilistic diagrams resulting from these analyses depict a more realistic assessment of the uncertainty associated with previously identified thresholds of channel form and instability and provide a means of gauging channel sensitivity to changes in controlling variables

a novel approach to model earth fissure caused by extensive aquifer exploitation and its application to the wuxi case china initially observed in the semi arid basins of southwestern usa earth fissures due to aquifer over exploitation are presently threatening a large number of subsiding basins in various countries worldwide different mechanics have been proposed to explain this process such as differential compaction horizontal movements and fault reactivation numerical modeling and prediction of this major geo hazard caused by overuse of groundwater resources are challenging because of two main requirements shifting from the classical continuous to discontinuous geomechanics and incorporating 2 dimensional features the earth fissures into large 3 dimensional 3d modeling domain the subsiding basin in this work we proposed a novel modeling approach to simulate earth fissure generation and propagation in 3d complex geological settings a nested two scale approach associated with an original non linear elasto plastic finite element interface element simulator allows modeling the mechanics of earth discontinuities in terms of both sliding and opening the model is applied on a case study in wuxi china where groundwater pumping between 1985 and 2004 has caused land subsidence larger than 2 m the model outcomes highlight that the presence of a shallow 80 m deep bedrock ridge crossing the yangtze river delta is the key factor triggering the earth fissure development in this area bending of the alluvial deposits around the ridge tip and shear stress due to the uneven piezometric change and asymmetrical shape of the bedrock have caused the earth fissure to onset at the land surface and propagate downward to a maximum depth of about 20 30 m maximum sliding and opening are computed in the range of 10 to 40 cm in agreement with the order of magnitude estimated in the field

holocene intracontinental deformation of the northern north china plain evidence of tectonic ground fissures abstract following the collecting and analyzing of field data on the geometry and kinematics characteristics of ground fissures in the northern north china plain nncp this paper shows that en echelon ground fissures or tectonic ground fissures with a length of several meters to tens of kilometers extending along active faults are possibly controlled by underlying active faults there are two groups of tectonic ground fissures developed in the nncp one group consists of ene trending right stepping ground fissures some of which have a component of sinistral motion the other group is nne trending left stepping ground fissures with dextral motion a large amount of data from trenches boreholes and seismic exploration reflect that they are active faulting related the nnw trending regional extensional stress field and the reactivation of pre existing faults are the major factors controlling ground fissures data from the quaternary sedimentary records deep incised valleys the distribution of earthquakes and ground fissures and our field work show that the holocene intracontinental deformation of the nncp is characterized by intense faulting and northwestward tilting which may be related to a nnw sse oriented tensional stress field in the shallow crust and asthenospheric upwelling in the mantle

sinkhole hazard assessment in minnesota using a decision tree model an understanding of what influences sinkhole formation and the ability to accurately predict sinkhole hazards is critical to environmental management efforts in the karst lands of southeastern minnesota based on the distribution of distances to the nearest sinkhole sinkhole density bedrock geology and depth to bedrock in southeastern minnesota and northwestern iowa a decision tree model has been developed to construct maps of sinkhole probability in minnesota the decision tree model was converted as cartographic models and implemented in arcgis to create a preliminary sinkhole probability map in goodhue wabasha olmsted fillmore and mower counties this model quantifies bedrock geology depth to bedrock sinkhole density and neighborhood effects in southeastern minnesota but excludes potential controlling factors such as structural control topographic settings human activities and land use the sinkhole probability map needs to be verified and updated as more sinkholes are mapped and more information about sinkhole formation is obtained

a typical earth fissure resulting from loess collapse on the loess plateau in the weihe basin china abstract earth fissures are major geological hazards that frequently occur in the weihe basin in northwestern china and can cause severe damage to infrastructure this paper reports a case study of earth fissures resulting from loess collapse in the village of xibai in the weihe basin a series of geological investigations consisting of a site investigation trench excavation geological drilling exploratory well drilling and geotechnical testing were conducted to determine and analyze the characteristics of the xibai village earth fissures as well as the physical characteristics of the loess in the earth fissure development area the earth fissures were parallel to the village sewage pit and had a total length of 800 m with a maximum depth of 8 5 m the xibai village earth fissures were nearly vertical comparing the results of self weight collapsibility coefficient and three parameters void ratio dry density and water content of loess at different distances from the sewage pit the collapsibility of malan loess in this area and the effects of leakage from the sewage pit were determined the results revealed that a tilted seepage line was generated and the loess below this seepage line underwent varying degrees of self weight collapse deformation the nonuniform collapse settlement and rotation deformation of loess above the seepage line were thus generated while tensile stress was created in the upper part of the loess this rotation of loess similar to the deformation of the cantilever beam caused the formation of the earth fissures at the site with higher tensile stress based on the rotation mechanism this study explained the development process of collapse earth fissures and predicted that the xibai village earth fissures would continue to develop outward in the future

statistical analysis of landslide susceptibility at yongin korea the aim of this study is to evaluate the susceptibility of landslides at yongin korea using a geographic information system gis landslide locations were identified in the yongin area from interpretation of aerial photographs field surveys and maps of the topography soil type timber cover and geology these data were collected and constructed into a spatial database using gis the factors that influence landslide occurrence such as slope aspect and curvature of topography were calculated from the topographic database texture material drainage and effective soil thickness were extracted from the soil database and type age diameter and density of timber were extracted from the forest database lithology was extracted from the geological database and land use was classified from the landsat tm satellite image landslide susceptibility was analyzed using the landslide occurrence factors by probability and logistic regression methods the results of the analysis were verified using the landslide location data the validation results showed satisfactory agreement between the susceptibility map and the existing data on landslide location the gis was used to analyze the vast amount of data efficiently and statistical programs were used to maintain specificity and accuracy the results can be used to reduce associated hazards and to plan land use and construction

river response to quaternary subsidence due to evaporite solution gallego river ebro basin spain abstract the stream terrace evolution of the gallego river during the quaternary was controlled by both climatic change and subsidence quaternary terrace deposits overlying tertiary clay and limestone are between 2 and 5 m thick whereas above evaporite formations the alluvial deposits may be as much as 110 m thick chronologically the first period of alluvial thickening involved the stream terraces t2 105 m above the present thalweg t3 95 m and t4 85 m which have been dated by paleomagnetic reversals as matuyama pre 780 000 the second subsidence period affected the deposits of the stream terrace t9 30 dated as brunhes post 780 000 in both thickening periods the subsidence was due to solution of the underlying evaporite formations halite and gypsum presumably during intervals of high water flow in the proposed model the valley subsidence was balanced by stream aggradation maintaining the river equilibrium profile the subsidence recorded in the alluvial deposits shows a complex spatial and temporal evolutionary pattern and total subsidence was assumed to be equal to the alluvial thickening for each subsidence period reaching up to 165 and 25 m respectively

geomorphological and sedimentological features in quaternary fluvial systems affected by solution induced subsidence ebro basin ne spain abstract the quaternary evolution and the morpho sedimentary features of some of the most important rivers in spain ebro and tagus rivers among others have been controlled by subsidence due to alluvial karstification of the evaporitic bedrock the subsidence mechanism may range from catastrophic collapse to slow sagging of the alluvium by passive bending in the ebro basin the mechanisms and processes involved in karstic subsidence were studied through the analysis of present day closed depressions as well as through old subsidence depressions palaeocollapses and solution induced basins and associated deformations recorded in the quaternary alluvial sediments the gallego ebro river system is presented as a case study of channel adjustments and geomorphic and sedimentary evolution of fluvial systems in dissolution induced subsidence areas in this fluvial system evaporite dissolution during particular quaternary time intervals namely early and middle pleistocene have lead to the development of a solution induced basin approximately 30 km long by 8 km wide filled by quaternary deposits with a total thickness in excess of 190 m the main river response to balance the subsidence in the alluvial plain was aggradation in the central reach of the subsiding area and degradation both in the upstream reach and in the valley sides where alluvial fans and covered pediments may prograde over the fluvial sediments the main sinking areas are recognized in the sedimentary record by anomalous thickenings in the alluvial deposits and fine grained sediments deposited in backswamp and ponded areas