permeability and fracture patterns in extrusive volcanic rocks implications from the welded santana tuff trans pecos texas the santana tuff of trans pecos texas is a nonwelded to thoroughly welded fractured vitric crystal tuff the unsaturated welded portions of the santana tuff were examined to determine its matrix permeability and fracture patterns more than 1 100 permeability measurements on tuff surfaces were taken with a gas minipermeameter independent variables included the degree of surficial weathering the presence of rock varnish and the orientation of the surface with respect to direction of emplacement and flattening the mean permeabilities for fresh weathered and varnished surfaces were 55 33 md 5 03 md and 3 31 md respectively the fresh surface measurements are significantly different from the other two surface types both of which were from statistically equivalent populations analyses on cut surfaces showed about a 30 decrease in permeability perpendicular to flow direction and flattening this trend was also evident on the varnished and weathered surfaces weathering rinds including the varnish decrease the permeability in thin section the rinds exhibit a thin layer of dark minerals mostly fe oxides sem photographs of the weathered and varnished surfaces show a lamellate texture indicative of coating by smectitic clay particles fracture patterns were examined at six outcrops spanning 9 km a pavement was mapped at one outcrop rose diagrams and stereonets were prepared from more than 300 observations although the composite data show two main orientations of nearly vertical cooling fractures the fracture trends vary considerably even between out crops in proximity to each other field observations indicate that fractures are continuous across individual flow boundaries at the mapped outcrop the fracture density and trace length are fractal between the 0 5 m and 3 m range the fractal dimension of fracture density was 1 44 and the length of the fracture was scale dependent but a fractal dimension of fracture lengths was not able to be determined a lower percentage of abutting fractures was observed here than has been noted in similar studies in nevada this study demonstrates that weathering along fractures reduces fracture matrix interactions in such rocks and that fracture patterns on a regional scale may be difficult to characterize

geological history of adelie land and king george v land antarctica evidence for a polycyclic metamorphic evolution abstract metamorphic and structural studies in adelie land and king george v land east antarctica show that this part of the east antarctic shield can be divided into four different sections the areas east of commonwealth bay show evidence for a polycyclic metamorphic evolution in which low pressure granulite facies m 1 fabrics 4 4 5 kbar 750 c are overprinted by retrograde hydrated decompression textures of amphibolite facies during m 2 and by late high pressure low temperature coronas during m 3 5 7 7 0 kbar 500 600 c the regional structure and relative timing of events in the other three areas is consistent with the recognition of these three metamorphic events the cape denison orthogneiss in commonwealth bay was intruded after the pervasive low pressure m 1 event but before the major ductile deformation phases and m 2 the cape denison orthogneiss therefore only suffered the m 2 amphibolite facies metamorphic event and subsequent overprinting by m 3 mid greenschist facies assemblages involving lawsonite the cape hunter phyllites were deposited after m 2 but before m 3 and consequently were only affected by the mid greenschist metamorphic event which also overprinted the amphibolite facies fabrics at cape denison the areas west of commonwealth bay underwent the low pressure granulite facies metamorphism during m 1 decompression during m 2 but no late m 3 overprint the variation of the grade of m 3 in the different areas from granulite facies pressures east of commonwealth bay to no effect west of cape hunter is interpreted as a consequence of differential uplift along shear zones with a north south strike which exposed successively deeper levels towards north victoria land to the east this spatial association and the age of m 3 may suggest that there is a connection between m 3 in king george v land and adelie land and the ross orogeny in north victoria land the recognition of three metamorphic events can be correlated with three radiometric ages previously established for the cape denison orthogneiss

development and morphometry of sinkholes in coastal plains of apulia southern italy preliminary sinkhole susceptibility assessment abstract evolution of coastlines in karst areas may be strongly controlled by dissolution processes which favour the development of surface and subsurface landforms the generation of caves in these environments is commonly favoured by the mixing between fresh and brackish waters the sinkholes resulting from the upward propagation of the caves may interfere with the anthropogenic environment and cause damage to human elements property and activities to highlight the often underestimated importance of karst phenomena in coastal areas we have analyzed a coastal stretch of apulia in southern italy the study area covering an extension of about 6 km 2 is situated in the ionian coast and presents several interesting karst landforms that are generally connected to caves tens of sinkholes were mapped through field surveys multi year aerial photographs dating back to the 1940s and archival research we have performed a morphometric analysis of the sinkholes the analysis describes the main parameters of the sinkholes area length width and depth and the control exerted by the main discontinuity systems in the area the detrimental effects derived from interaction between human environment and these karst landforms is also under consideration a sinkhole susceptibility map which may provide useful information for planners developers and the insurance industry has eventually been produced through application of a decision tree model

low pressure granulite facies metamorphism in the larsemann hills area east antarctica petrology and tectonic implications for the evolution of the prydz bay area thermobarometric studies on various granulite facies areas along the prydz bay coast east antarctica 73 79 e 68 70 s show that at around 1100 ma during a late proterozoic orogeny the rocks of the larsemann hills suffered a lower pressure metamorphic peak than the surrounding areas along the prydz bay coast the rocks affected by this event include parts of the vestfold hills block plus all of the rauer group the larsemann hills and the munro kerr mountains the dykes in the south west corner of the vestfold hills were recrystallized during this event with little deformation at temperatures not quite as high as in the areas further south west 650 c 6 5 kbar collerson et al 1983 the rauer group was metamorphosed at 800 c and 7 5 kbar harley 1987a the larsemann hills at 750 c and 4 5 kbar and the munro kerr mountains probably at around 850 c and 5 kbar retrograde equilibration in the different areas occurred during decompression to about 10 km depth in all areas followed by isobaric cooling at this depth this paper shows that the peak metamorphism in the larsemann hills occurred at a pressure which is too low to have been the consequence of thermal relaxation of overthickened crust with normal mantle heat flow although other areas in prydz bay were metamorphosed at sufficiently high pressures so that their decompression paths are not inconsistent with a continental collision model the inferred pre metamorphic peak histories and the requirement of consistency with the larsemann hills make it unlikely that collision followed by erosion driven decompression is an appropriate model we suggest that the thermal regime of the crust in the larsemann hills region was controlled by a perturbation in the asthenosphere with magma invasion of the crust we suggest that the 500 ma event represented in prydz bay by granitic outcrops at landing bluff and by several k ar ages from the larsemann hills area was responsible for the final excavation of the terrane

use of sinkhole and specific capacity distributions to assess vertical gradients in a karst aquifer the carbonate rock aquifer in the great valley west virginia usa was evaluated using a database of 687 sinkholes and 350 specific capacity tests to assess structural lithologic and topographic influences on the groundwater flow system the enhanced permeability of the aquifer is characterized in part by the many sinkholes springs and solutionally enlarged fractures throughout the valley yet vertical components of subsurface flow in this highly heterogeneous aquifer are currently not well understood to address this problem this study examines the apparent relation between geologic features of the aquifer and two spatial indices of enhanced permeability attributed to aquifer karstification 1 the distribution of sinkholes and 2 the occurrence of wells with relatively high specific capacity statistical results indicate that sinkholes funnel and collapse occur primarily along cleavage and bedding planes parallel to subparallel to strike where lateral or downward vertical gradients are highest conversely high specific capacity values are common along prominent joints perpendicular or oblique to strike the similarity of the latter distribution to that of springs suggests these fractures are areas of upward convergent flow these differences between sinkhole and high specific capacity distributions suggest vertical flow components are primarily controlled by the orientation of geologic structure and associated subsurface fracturing

analysis of dolines using multiple methods applied to airborne laser scanning data abstract delineating dolines is not a straightforward process especially in densely vegetated areas this paper deals quantitatively with the surface karst morphology of a miocene limestone occurrence in the styrian basin austria the study area is an isolated karst mountain with a smooth morphology former planation surface of pliocene age densely vegetated mixed forest and with a surface area of 1 3 km 2 the study area is located near the city of wildon and is named wildoner buchkogel the aim of this study was to test three different approaches in order to automatically delineate dolines the data basis for this was a high resolution digital terrain model dtm derived from airborne laser scanning als and with a raster resolution of 1 1 m the three different methods for doline boundary delineation are a the traditional method based on the outermost closed contour line b boundary extraction based on a drainage correction algorithm filling up pits and c boundary extraction based on hydrologic modelling watershed extracted features are integrated in a gis environment and analysed statistically regarding spatial distribution shape geometry elongation direction and volume the three methods lead to different doline boundaries and therefore investigated parameters show significant variations the applied methods have been compared with respect to their application purpose depending on delineation process between 118 and 189 dolines could be defined the high density of surface karst features demonstrates that solutional processes are major factors in the landscape development of the wildoner buchkogel furthermore the correlation to the landscape evolution of the grazer bergland is discussed

metamorphism and granite genesis in the hidaka metamorphic belt hokkaido japan the main zone of the hidaka metamorphic belt is an uplifted crustal section of island arc type the crust was formed during early tertiary time as a result of collision between two arc trench systems of cretaceous age the crustal metamorphic sequence is divided into four metamorphic zones i iv in which zone iv is in the granulite facies a detailed study of the evolution of the hidaka belt based on a revised p t t analysis of the metamorphic rocks notably a newly found staurolite bearing granulite confirms a prograde isobaric heating path after a supposed event of tectonic thickening of accretionary sedimentary and oceanic crustal rocks during the peak metamorphic event c 53 ma the regional geothermal gradient attained 33 40 c km 1 and the highest p t condition obtained from the lowest part of the granulite unit is 830 c 7 kbar in this part xh2o of gt opx cd gneiss is about 0 15 and that of gt cd bt gneiss is 0 4 the p t xh2o condition of the granulite unit is well within a field where fluid present partial melting of pelitic and greywacke metamorphic rocks takes place this is in harmony with the restitic nature of the gt opx cd gneiss in the lowest part of the granulite unit the possibility that partial melting took place in the main zone is significant for the genesis of the peraluminous s type granitic rocks within it the s type granitic rocks in this zone are opx gt bt tonalite in the granulite zone gt cd bt tonalite in the amphibolite zone and cd bt mus tonalite in the bt mus gneiss zone the mineralogical and chemical nature of these strongly peraluminous tonalitic rocks permit them to be regarded as having been derived from s type granitic magma generated by crustal anatexis of pelitic metamorphic rocks in deeper crust

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

experimental study on the critical triggering condition of soil failure in subsidence sinkholes subsidence sinkholes in karst terrain are a common geological hazard which can lead to natural disasters in the natural and built environment groundwater ingress is the main factor leading to subsidence previous research has focused on the qualitative analysis of the influence of groundwater although limited research into critical triggering conditions of groundwater has been undertaken quantitatively water seepage into soil is the starting condition in the development of subsidence sinkholes this paper focuses on testing the anti permeability strength as the critical triggering condition in the formation of subsidence sinkholes and develops a design and methodology to test its value quantitatively the methodology is applied in an industrial park of guilin china to assess the probability of forming subsidence sinkholes results indicate that there is a low susceptibility to the formation of subsidence sinkholes under current conditions in the ground truth investigation

earthquake prediction an empirical approach abstract earthquake precursor data so far accumulated in japan have shown that the larger the main shock magnitude the larger the distance between the epicenter and an observation point where a precursor is observed it is possible to empirically establish an approximate relationship between maximum detectable distance d max and main shock magnitude m the relationship being different from discipline to discipline of precursor when a number of precursors are observed we may draw circles with a radius equal to d max peculiar to each precursor discipline centered at the respective observation points on the condition that m takes on a certain value in that case the epicenter of a future earthquake should be located in the area which is common to all of the circles if m is too small some of the circles do not overlap if it is too large an epicentral area which is too wide to be realistic must be assumed in this way an approximate epicenter location and a rough value of the main shock magnitude can be assessed applying the procedure to the precursors of the izu oshima kinkai m 7 0 1978 and the niigata m 7 5 1964 japan earthquakes remarkable success is achieved probabilities of an earthquake occurring in a specified time interval can be evaluated as a function of time when a precursor is observed for such an evaluation we rely either on the log t m relationship with a prescribed value of m or on the frequency distribution of log t which is empirically obtained depending on precursor disciplines t being the precursor time when a number of precursors are observed one by one changes in synthetic probability of earthquake occurrence can be estimated according to the existing formula utsu 1977 as an example such probability changes with time are estimated making use of the precursor data for the izu oshima kinkai earthquake it turns out that the synthetic probability generally increases as time goes on when a long term precursor happens to be observed however the probability drops discontinuously being followed by a gradual rise again the temporal change in probability therefore shows considerable fluctuations this is especially so when a short interval for probability evaluation is specified because of uncertain preliminary probability involved in the evaluation and an unknown rate of false precursor signals against true ones the absolute value of probability thus evaluated may not be perfectly reliable even so the temporal change in probability may provide some clues for the actual publication of earthquake prediction

two stage decompression in garnet bearing mafic granulites from sostrene island prydz bay east antarctica mafic garnet bearing granulites from sostrene island 150 km southwest of davis station on the coast of prydz bay east antarctica exhibit two stage symplectic coronas on garnet formed after peak metamorphic conditions m1 an outer corona of opx mg66 pl an94 97 minor hbl mantles a finer grained inner corona of opx mg67 pl an95 96 spl mg36 both symplectites contain minor ilmenite magnetite intergrowths the finer grained symplectite also occurs along a fracture cleavage in the garnet the outer corona originated during a second metamorphic event m2 via the reaction grt cpx hbl sio2 opx pl 1 whereas the inner corona formed later in response to decompression and minor deformation resulting in the fracture cleavage in the garnet according to the reaction grt opx pl spl 2 the grossular content of the garent xgrs 0 168 is almost exactly that which is required for the stoichiometric breakdown by reaction 2 calculated xgrs 0 167 the mafic rocks are silica undersaturated and the sio2 for reaction 1 was most probably derived externally from the surrounding felsic gneisses preferred p t estimates for m1 based on garnet core prp40alm42grs17sps1 matrix opx cpx hbl pairs are c 10 kbar at 980 c the fine grained symplectite formed post peak m2 at c 7 kbar and 850 c the enclosing felsic gneisses yield pressure estimates of between 5 and 7 kbar which compare with conditions of c 6 kbar and 775 c in the nearby bolingen islands these lower p t estimates are considered to be representative of the widespread 1100 ma metamorphic event recognized in outcrops along the prydz bay coast the high p high t estimates derived from the garnet relics provide evidence for an earlier possibly archaean high grade metamorphic event

automated delineation of karst sinkholes from lidar derived digital elevation models abstract sinkhole mapping is critical for understanding hydrological processes and mitigating geological hazards in karst landscapes current methods for identifying sinkholes are primarily based on visual interpretation of low resolution topographic maps and aerial photographs with subsequent field verification which is labor intensive and time consuming the increasing availability of high resolution lidar derived digital elevation data allows for an entirely new level of detailed delineation and analyses of small scale geomorphologic features and landscape structures at fine scales in this paper we present a localized contour tree method for automated extraction of sinkholes in karst landscapes one significant advantage of our automated approach for sinkhole extraction is that it may reduce inconsistencies and alleviate repeatability concerns associated with visual interpretation methods in addition the proposed method has contributed to improving the sinkhole inventory in several ways 1 detection of non inventoried sinkholes 2 identification of previously inventoried sinkholes that have been filled 3 delineation of sinkhole boundaries and 4 characterization of sinkhole morphometric properties we applied the method to fillmore county in southeastern minnesota usa and identified three times as many sinkholes as the existing database for the same area the results suggest that previous visual interpretation method might significantly underestimate the number of potential sinkholes in the region our method holds great potential for creating and updating sinkhole inventory databases at a regional scale in a timely manner

a multiple fracture model of pre seismic electromagnetic phenomena abstract among three main stages of the process of earthquake nucleation long middle and short term the final stage is characterized by abrupt activation of the process of stress strain state variation the strain rates increase by orders of magnitude throughout the whole region of preparation which increases the signal to noise ratio and therefore the fracture is easier to detect through monitoring geophysical parameters the near critical stresses existing in the earth s crust and near the surface make it necessary to take into account the real rheology of the rocks which as is well known is characterized by clearly pronounced plastic properties the condition is favorable for developing creep processes in general and in its avalanche phase immediately before the fracture the process is completely nonlinear but not chaotic based on the assumption that the attenuation of the stress strain field is proportional to r 3 a possible scenario of the final stage of earthquake nucleation process is proposed on the basis of the slip weakening mechanism in the source and the associated mosaic pattern of precursors on the earth s surface the formulas for estimating the ultimate distance of precursor detection and the duration of precursor events depending of normalized epicentral distance at the final stage of inelastic deformation preceding brittle failure of rocks are proposed the data of electromagnetic precursors are interpreted in terms of a multiple fracture model the results of in situ observations of electric field anomalies in the atmosphere are analyzed in relation to seismic activity the possibility of constructing a physical model for the generation of a quasi stable field and electromagnetic emission on the basis of the deformation process prior to an earthquake is discussed numerical estimates are obtained for polarization density and life time of an ensemble of electric dipoles generated in surface layers of the crust due to opening of microcracks and other dislocation mechanisms the origin of quasi constant electric field along a deformation region on a scale of the preparation zone is advantageous for the propagation of seismic anomalous atmospheric electric fields from the earth s surface into the ionosphere the field can be regarded as a physical agent of lithosphere ionosphere connection

re evaluation of rock core logging for the prediction of preferred orientations of karst in the kuala lumpur limestone formation based on the relationship between the geological structures and river patterns the preliminary prediction of the karstic features in the kuala lumpur limestone formation based on the existing geological map appears to be directed between n030 to 070 and n120 to 150 the factual evidence of this occurrence is obtained from investigation in the field first using the two sites exposed for construction of the smart tunnel under kuala lumpur and second based on the smart tunnel project rock cores recovery a much detailed prediction was made by re evaluating the tcr rqd and scr values the reassessment of these values enables the drilled ground to be classified into four different qualities of rock mass good quality limestone moderate quality limestone weathered limestone and fully developed void like karst according to this new classification system the tunnel appears to align generally in the heavily karstified limestone in the northern section and massive good quality limestone in the southern section of the study area which is represented as rose diagrams the evidence for this analysis is given and the methods used for these studies are explained

application of matrix analysis in delineating sinkhole risk areas along highway i 70 near frederick maryland sinkhole collapse in the area of maryland interstate 70 i 70 and nearby roadways south of frederick maryland has been posing a threat to the safety of the highway operation as well as other structures the occurrence of sinkholes is associated with intensive land development however the geological conditions that have been developing over the past 200 million years in the frederick valley control the locations of the sinkholes within an area of approximately 8 km 2 138 sinkholes are recorded and their spatial distribution is irregular but clustered the clustering indicates the existence of an interaction between the sinkholes the point pattern of sinkholes is considered to be a sample of a gibbsian point process from which the hard core strauss model is developed the radius of influence is calculated for the recorded sinkholes which are most likely to occur within 30 m of an existing sinkhole the stochastic analysis of the existing sinkholes is biased toward the areas with intensive land use this bias is adjusted by considering 1 topography 2 proximity to topographic depressions 3 interpreted rock formation 4 soil type 5 geophysical anomalies 6 proximity to geologic structures and 7 thickness of overburden based on the properties of each factor a scoring system is developed and the average relative risk score for individual 30 m segments of the study area is calculated the areas designated by higher risk levels would have greater risk of a sinkhole collapse than the areas designated by lower risk levels this risk assessment approach can be updated as more information becomes available

progressive sequence of reactions of the ryoke metamorphism in the yanai district southwest japan the formation of cordierite the compositions of biotite and muscovite were examined in terms of the paragenesis and the metamorphic grade in low to medium grade pelitic rocks of the ryoke metamorphism in the yanai district southwest japan the biotite and muscovite that coexist with k feldspar have a higher k component in an a kf diagram than those in rocks lacking k feldspar this fact reflects an increase in the k2o content in muscovite but in biotite it reflects an increase of not only the k2o content but also of the octahedral vacancy at higher metamorphic grade beyond the cordierite isograd where cordierite coexists with neither chlorite nor k feldspar the biotite shows an increase in illite k aliv xii 1 si 1 and tschermak components alvi aliv r 1 si 1 where xii and r denote the interlayer vacancy and fe mg mn respectively a reaction to define the cordierite isograd is proposed by treating this chemical change as being responsible for the first appearance of cordierite i e k al poor biotite phengitic muscovite k al rich biotite cordierite quartz water by treating this as a key reaction in medium grade metamorphism a set of reaction in a progressive metamorphism is established for the ryoke metamorphism a typical low pressure type metamorphism some textures in one of the high grade areas the k feldspar cordierite zone suggest that a further two prograde reactions have taken place i e andalusite biotite quartz cordierite k feldspar water and andalusite sillimanite quartz cordierite k feldspar water this implies that this zone probably has a p t path involving isobaric heating

spatial analysis of a karst depression population clues to genesis a detailed analysis of depression spatial distribution on the parts of the western highland rim and pennyroyal plain underlain by the st louis and ste genevieve limestones indicates the presence of a depression infrastructure the major geomorphic elements of the infrastructure include depression density no km 2 doline swallet order and interdoline spacing a multigenerational diffusion and competition process model best explained 1 the presence of two lognormally distibuted depression density subpopulations 2 discrete clustered depression sets containing second order swallet dolines surrounded by first order swallet depressions 3 geomorphic competition between adjacent second order swallet dolines for runoff and catchment area and 4 a positive correlation between interdoline rim spacings of the small swallet order and the sum of their respective major axial lengths

macro anomaly and its application to earthquake prediction abstract macro anomalies preceding a number of large earthquakes in japan are analyzed in relation to maximum detectable distance d max from the epicenter and to precursor time t between anomaly appearance and main shock occurrence these anomalies include anomalous animal behaviour strange detonation unusual light in the sky change in underground water and hot springs and are all things which can be sensed by humans without using scientific instruments the number of anomalies analyzed amounts to 910 as a result an approximate relation between main shock magnitude m and d max is brought out given an m therefore it is possible to draw a circle having a radius equal to d max centering at the spot where an anomaly is observed in that case the epicenter of coming earthquake must lie within that circle when there are multiple anomalies the epicenter should be located somewhere in an area where all the circles overlap it will be shown that such a d max method leads us to an assessment of the approximate epicentral area and main shock magnitude it appears that macro anomalies begin to be observed about 100 days before the main shock anomaly numbers tending to increase at around t 10 days in most cases the maximum frequency of appearance usually occurs around 1 day prior to the main shock the distribution of frequency can well be approximated by a weibull distribution making use of parameters of the distribution changes in probability of earthquake occurrence in a specified time interval can be evaluated when an anomaly is observed when many anomalies are observed successively time changes in the synthetic probability can be evaluated it appears that such a probability tends to increase reaching a value close to 1 as the main shock occurrence approaches and the frequency of anomaly appearances increases although no actual pre earthquake prediction based on macro anomaly data has as yet been conducted it is hoped that the technique developed in this paper will be applied to anomaly data related to coming earthquakes once a well organized data acquisition system comes into operation the authors are of the opinion that macro anomalies may be applied at least to some extent to earthquake prediction despite the traditional view that macro anomalies are so unreliable and contaminated by noise that they cannot be used for prediction

sinkholes and caves related to evaporite dissolution in a stratigraphically and structurally complex setting fluvia valley eastern spanish pyrenees geological geomorphological and environmental implications abstract evaporite karst and sinkhole development is analysed in a geologically complex area of ne spain including four evaporite units with different characteristics and affected by compressional and extensional tectonic structures the exposed paleosinkholes including remarkable early pleistocene paleontological sites provide valuable information on the subsidence mechanisms and reveal the significant role played by interstratal karstification in the area these gravitational deformation structures including hectometre scale bending folds and oversteepened normal faults strongly suggest that the present day compressional regime inferred in previous studies may be largely based on the analysis of non tectonic structures two gypsum caves ca 1 km long show that passages with restricted cross sectional area may produce large breccia pipes and sinkholes thanks to the removal of breakdown boulders by high competence episodic floods moreover the upward progression of cave ceilings by paragenesis and condensation dissolution contributes to increase the probability of sinkhole occurrence an inventory of 135 sinkholes together with their geological and geomorphological context has been developed this data base has been used to infer several properties of the sinkholes with practical implications a magnitude and frequency scaling relationship spatial distribution patterns dominant controlling factors and risk implications

morphometric properties of dolines in matarsko podolje sw slovenia matarsko podolje in sw slovenia is a karstic surface with many dolines which appear between the flysch composed brkini hills in the ne and mt slavnik in the sw we have analyzed dolines to find the morphometric parameters of the depth area volume and circularity index and also calculated the doline density and pitting index all parameters were also calculated separately for individual lithological units to explain the variations of the calculated values among these groups morphometry was performed in gis environment on a 1 1 m digital elevation model with bare earth obtained by lidar the results show a high density of dolines 94 dolines km2 and also a high pitting index rp 8 27 compared to other studies there are some significant differences between the measured values in individual lithologies as the depths areas and volumes are largest in dolomitic beds other beds include various types of limestones and carbonate breccia the median values of depth area and volume are 2 98 m 541 m2 and 690 m3 the circularity index is also lowest in dolomite beds and kozina limestones however the differences are not so pronounced as for areas and volumes dolines longer axes are parallel to the directions of major structural elements however more detailed mapping should be done to confirm the influence of faults and fracture zones on the doline geometry

earthquake precursors in japan precursor time and detectability abstract earthquake precursor data amounting to 418 in number accumulated in japan are analyzed most data are obtained under the nation wide earthquake prediction programme the precursor time t versus main shock magnitude m relationship is different for different groups of precursors a linear relation such as log t a bm where a and b are constants seems to hold for precursor disciplines such as land deformation revealed by geodetic survey and tide gauge observation ground tilt observed by a water tube tiltmeter anomalous seismic activity and geomagnetic field change although a similar relationship seems to hold for the disciplines of earth currents radon concentration underground water etc the precursor time is substantially smaller for these disciplines than for the former disciplines the above characteristics of precursor time suggests that precursors closely connected to the dilatancy generation seem to be observed at an earlier stage of seismogenetic activity precursors probably associated with diffusion of underground water into the dilatant region seem to follow for a number of precursor disciplines such as foreshock ground tilt observed by a pendulum tiltmeter resistivity by a variometer and so on no dependence of t on m is found the relationship between m and the logarithmic epicentral distance d measured in kilometers is different from discipline to discipline relying on empirical and theoretical studies of coseismic strain step it turns out that precursors found by geodetic and geomagnetic observations seem to reflect a crastal strain of the order of 10 7 10 6 precursors obtained by a resistivity variometer seem to represent a strain of the order of 10 9 10 8 precursors of other disciplines seem to correspond to a strain of 10 8 10 7 it is clear that precursors can be detected further from the epicenter as the main shock magnitude becomes larger in some favourable cases a precursor can be observed even where the epicentral distance is several times larger than that of the epicentral area

earthquake prediction a critical review summary earthquake prediction research has been conducted for over 100 years with no obvious successes claims of breakthroughs have failed to withstand scrutiny extensive searches have failed to find reliable precursors theoretical work suggests that faulting is a non linear process which is highly sensitive to unmeasurably fine details of the state of the earth in a large volume not just in the immediate vicinity of the hypocentre any small earthquake thus has some probability of cascading into a large event reliable issuing of alarms of imminent large earthquakes appears to be effectively impossible key word earthquake prediction

ongoing long term evolution of an unconformity that originated as a karstic surface in the late miocene a case study from the cayman islands british west indies abstract on grand cayman and cayman brac karst development on the upper surface of the cayman formation during the late miocene lowstand produced the cayman unconformity on grand cayman this led to the development of a deep atoll shaped depression on the western part of the island the ensuing lower pliocene transgression buried that unconformity and led to deposition of sediments that now form the pedro castle formation today on grand cayman the dolostones of the cayman formation remain largely buried on the western half of grand cayman but are widely exposed on the central and eastern parts of the island where they have been subjected to extensive weathering over the last 4 3 ma although the situation is similar on cayman brac uplift of the central core led to removal of the pedro castle formation and much of the cayman formation karst development on both islands reflects the interplay between neogene sea level changes climate and tectonic uplift today weathering is further modifying the cayman unconformity on the eastern parts of both islands the cayman unconformity on the central and eastern parts of grand cayman is characterized by karst landforms including a peripheral rim sinkholes solution widened joints and photolineaments surface traces of joints and or faults the westward tilting of cayman brac 4 3 ma to 400 ka led to more severe weathering of the exposed cayman formation that included 1 enhancement of the peripheral rim and karst features on the upslope margin and 2 higher denudation rates than on grand cayman during the messinian the denudation rate on the west end of grand cayman was 0 03 0 10 mm yr 1 in contrast the denudation rate over the an estimated period of 4 9 to 6 2 ma for the eastern half of grand cayman has been about 0 01 mm yr 1 whereas on the east end of cayman brac it has been 0 03 0 04 mm yr 1 on both islands substantial thicknesses of strata have been lost to erosion and the cayman unconformity has been subject to ongoing modification over a period of 4 9 to 6 2 ma

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

metamorphic evolution of the southern part of the hidaka belt hokkaido japan the hidaka metamorphic terrane in the meguro shoya area hokkaido japan is divided into four progressive metamorphic zones a biotite zone b cordierite zone c cordierite k feldspar zone and d sillimanite k feldspar zone of the andalusite sillimanite facies series type of metamorphism the metamorphic grade ranges from the higher temperature part of the greenschist facies zone a through the amphibolite facies zones b and c to the lower temperature part of the granulite facies zone d the zone boundaries intersect the bedding planes at high angles p t conditions estimated are 450 550 c and 2 kbar for zone a 550 600 c and 2 2 5 kbar for zone b 600 650 c and 2 5 3 kbar for zone c and 650 750 c and 3 4 kbar for zone d the metapelites of zone d were partially melted at the later stage of the regional metamorphism which is early oligocene to early miocene in age cordierite tonalite and biotite tonalite intrusives associated with segments of the highest grade rocks zone d were emplaced into the lower temperature part of the regional metamorphic rocks giving rise to a contact metamorphic aureole the thermally metamorphosed terrain zone c belongs to the amphibolite facies and its p t conditions are estimated to have been 550 700 c and 2 kbar the p t t paths of the hidaka metamorphism show a thickening heating uplifting process the metamorphism is inferred to have taken place beneath an active island arc accompanied by partial melting of the crust

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

results of statistical analysis of low frequency seismogenic em emissions as precursors to earthquakes and volcanic eruptions abstract since 1980 we have detected impulsive noise bursts of seismogenic emissions at 82 khz 1525 hz and 36 hz with a multipoint detection network around the tokyo region and the izu peninsula in earlier times this system has recorded em signals prior to several earthquake events and it has also recorded volcanic eruptions on 15 and 21 november 1986 at mt mihara on ohshima island on 12 july 1989 in itoh bay in the izu peninsula region and since june 1991 at mt unzen on the shimabara peninsula to obtain a clear explanation of the source mechanism of these emissions we are progressing with statistical analyses of these emission characteristics using the data of 29 events over the last 5 years

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

anomalous crustal movements prior to great earthquakes as derived from tide gauge records the messina 1908 i xi earthquake case history abstract strain precursors prior to great earthquakes determined from tide gauge records worldwide are discussed the records at four sites in the tyrrhenian sea 1883 1922 are used to identify an anomaly in the sea level before the catastrophic messina earthquake of december 28 1908 with io xi there are pre seismic co seismic and post seismic phases in the crustal movements the pre seismic anomaly began at least 5 8 years before the event t 5 8 yr and occurred as far as 530 870 km d 530 870 km from the epicentre the strain precursors of this earthquake are compared with other similar cases and the worldwide relations of m d and m t

evaluating and comparing methods of sinkhole susceptibility mapping in the ebro valley evaporite karst ne spain abstract multiple sinkhole susceptibility models have been generated in three study areas of the ebro valley evaporite karst ne spain applying different methods nearest neighbour distance sinkhole density heuristic scoring system and probabilistic analysis for each sinkhole type separately cover collapse sinkholes cover and bedrock collapse sinkholes and cover and bedrock sagging sinkholes the quantitative and independent evaluation of the predictive capability of the models reveals that 1 the most reliable susceptibility models are those derived from the nearest neighbour distance and sinkhole density these models can be generated in a simple and rapid way from detailed geomorphological maps 2 the reliability of the nearest neighbour distance and density models is conditioned by the degree of clustering of the sinkholes consequently the karst areas in which sinkholes show a higher clustering are a priori more favourable for predicting new occurrences 3 the predictive capability of the best models obtained in this research is significantly higher 12 5 82 5 than that of the heuristic sinkhole susceptibility model incorporated into the general urban plan for the municipality of zaragoza although the probabilistic approach provides lower quality results than the methods based on sinkhole proximity and density it helps to identify the most significant factors and select the most effective mitigation strategies and may be applied to model susceptibility in different future scenarios

arc generated blocks with crustal sections in the north atlantic craton of west greenland crustal growth in the archean with modern analogues abstract the ca 700 km long archean craton of west greenland consists of six meso neoarchean ca 3000 2720 ma shear zone bounded crustal blocks that display similar cross sections from south to north ivittuut kvanefjord bjornesund sermilik fiskefjord maniitsoq each block has a southerly upper and a northerly lower zone thus each faces upwards to the south upper zones have prograde amphibolite facies mineralogy and have never been in the granulite facies whereas lower zones reached granulite facies and were partly retrogressed to amphibolite facies upper and lower zones consist predominantly of tonalite trondhjemite granodiorite ttg orthogneisses geochemistry suggests generation by slab melting in subduction settings of island arcs and active continental margins the gneisses contain km thick metavolcanic amphibolite layers typically bordered by km thick layers containing anorthosite and leucogabbro most upper zones contain upper greenschist to amphibolite facies metavolcanic belts including volcaniclastic andesitic rocks the two most prominent metavolcanic belts in the fiskefjord block at qussuk andesitic volcaniclastic rocks garde a a 2007 a mid archaean island arc complex in the eastern akia terrane godthabsfjord southern west greenland journal of the geological society london 164 565 579 and ivisaartoq mafic ultramafic rocks and anorthosite leucogabbro from upper and lower parts of a supra subduction zone system polat a frei r appel p w u dilek y fryer b ordonez calderon j c yang z 2008 the origin and compositions of mesoarchean oceanic crust evidence from the 3075 ma ivisaartoq greenstone belt sw greenland lithos 100 293 321 have island arc geochemical signatures the 2 km thick fiskenaesset complex bjornesund block comprises chromite layered anorthosites leucogabbros and gabbros and local pillow bearing roof pendants from overlying metavolcanic amphibolite the style of deformation changes downwards within crustal blocks upper zones are characterised by linear metavolcanic belts deformed by mostly one major phase of isoclinal folding and lower zones by kilometre scale double triple fold interference patterns everywhere ttg protoliths have intruded anorthositic and volcanic rocks typically along ductile shear zones often so extensively that only anorthositic or amphibolitic lenses are preserved the meso neoarchean crust was thickened by a combination of thrusting isoclinal folding and continued ttg injection dissimilarities in the proportions of anorthositic and metavolcanic rocks in the six blocks suggest that they evolved in several different microcontinents but by similar processes these crustal blocks provide an exceptional example of how continents evolved in the meso neoarchean comparable archean examples in kapuskasing and pikwitonei canada and modern analogues in fiordland new zealand kohistan himalayas southern california batholith peruvian andes and hidaka japan demonstrate that processes of continental growth from island arc to continental arc magmatism and by implication to continental collision were broadly similar throughout most of earth history

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

actual extension of sinkholes considerations about geophysical geomorphological and field inspection techniques in urban planning projects in the ebro basin ne spain abstract aerial photographs historical cartographies and field inspection are useful tools in urban planning design on mantled karst because they permit a wide time interval to be analyzed in the case of zaragoza city several works have confirmed the interest of these approaches in configuring the urban planning code and therefore represent a promising technique nevertheless some caveats should be taken into account when using this kind of information a detailed analysis is presented comparing in a case study from the surroundings of zaragoza geomorphological historical analysis and field inspection with geophysical data field inspection in a noncultivated area permits the constraint of the presence of karst indicators below the geomorphological resolution of aerial photographs and shows results consistent with geophysical surveys the studied case shows an inner zone coinciding with the sinkhole mapped from aerial photographs that correlates with changes in the position of the substratum and changes in thickness of alluvial sediments the integrated analysis permits us to define an external subsidence ring around the geomorphological sinkhole whose surface is twice the size of the inner zone this outer ring is indicated by geometrical changes in gpr profiles increases of thickness of the conductive shallower unit toward the collapse and small collapses on marginal cracks these results support the higher extension of karst hazards linked to sinkholes with respect to their geomorphological expression and the needed detailed analysis to constrain the real sinkhole size or the use of security radii surrounding this surficial evidence when geomorphological data is used for the hazard analyses or the urban planning at karstic zones

linear and nonlinear dynamics in electrical precursory time series implications for earthquake prediction abstract the time dynamics of geoelectrical precursory time series has been investigated using autoregressive models the approach used here allows us to obtain information on the geophysical system producing the electrical phenomena in seismic active areas when the only information about the time series comes from the time series themselves it is based on two forecasting approaches the global autoregressive approximation and the local autoregressive approximation the first approach views the data as a realization of a linear stochastic process whereas the second approach considers the data points as the results of a deterministic process supposedly nonlinear the comparison of the predictive skills of the two techniques is a strong test to distinguish between low dimensional chaos and random dynamics our findings give us insight in the inner dynamics of the geophysical process under study an estimate of the number of degrees of freedom of the dynamical system governing the electrical phenomena is obtained the stochastic nature of the electrical precursory signals has been highlighted and the possible implications for the earthquake prediction problem are discussed the processed time series are geoelectrical measurements recorded by an automatic station located in tito southern italy which is one of the most seismic areas of the mediterranean region we found that the global linear approach is superior to the local one and the physical system governing the phenomena of electrical nature is characterized by a large number of degrees of freedom the results are confirmed by the presence of rich scaling properties in the power spectra of the processed electrical signals

thermal modelling in low pressure high temperature metamorphic belts abstract low pressure high temperature metamorphic belts occur throughout the world they display a characteristic metamorphic style which has remained unchanged with time they are found in disparate tectonic settings including magmatic arcs regions of extension regions of thickened crust in continent continent collision zones and accretionary wedges they are commonly characterized by an abundance of granitoid plutons pressures of metamorphism are primarily less than or equal to that of the aluminosilicate triple point approximately 4 kbar while temperatures are in the range 500 750 c with rare exceptions inferred ptt paths are nearly isobaric and recrystallization was rapid and prograde metamorphic thermal gradients are commonly in the range 60 150 c km these conditions necessitate the presence of a large component of advective heat transfer and or anomalously high basal heat flow during metamorphism the large magmatic fluxes associated with the formation of magmatic arcs provide an adequate heat source for low pressure metamorphism lpm lithospheric extension is likely to produce lpm only if the degree of thinning is large 3 and there is additional heat from magmas the generation of lpm by crustal thickening requires either a large component of advective heating by magmas anomalously high basal heat flow or pre thickening lithospheric extension lpm in this environment must necessarily be accompanied by plutonic activity advection of heat by aqueous fluids may provide a significant contribution to the thermal budget but acting along is unlikely to produce lpm regional lpm induced by advective sources rarely occurs along a geotherm which increases monotonically with depth or synchronously across the region at a given depth it occurs over time as a series of overlapping temporally separate and spatially localized thermal events

1 fα fluctuations in geoelectrical signals observed in a seismic area of southern italy abstract recent studies have shown that many natural systems display temporal fluctuations with long range power law correlations suggesting a fractal geometry of the underlying dynamical system four geoelectrical time series measured in a seismic area of southern italy are investigated by means of spectral tools in order to evidence the existence of power law correlations results show the scaling behaviour for all the signals recorded pointing to the presence of fractal features expressing a long term correlation with scaling exponents which indicate stabilizing mechanisms furthermore our findings suggest an observational evidence of correlations between the variation of parameters describing the temporal fluctuations of geoelectrical signals and earthquakes that occurred in the area investigated

volcanic eruptions and wide area geophysical anomalies abstract the changes in volume linear strain and underground water level temperature observed in association with the november 21 1986 eruption of mihara volcano about 110 km southwest of tokyo japan are analyzed these changes were observed at many mainland stations several tens of kilometers distant from the volcano the so called d max method was originally invented by the writer for predicting the location and magnitude of an earthquake based on precursor data applying this technique to the geophysical anomalies observed it is concluded that the event center was located somewhere beneath the volcano and that the effective magnitude was approximately 5 8 the method relies on the empirical relation between maximum detectable distance of an earthquake precursor from the epicenter d max and the main shock magnitude m the relation is a function of the type of precursor assuming a spherical magma reservoir underneath the volcano having a specific pressure cavity radius and so on it is proved that the effective magnitude is in accord with the strain energy change associated with the pressure release at the time of eruption the model also accounts for the amount of crustal deformation actually observed it is thus concluded that the d max method is valid not only for earthquake precursors but also for analyzing geophysical anomalies associated with a volcanic eruption

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

evaluation of susceptibility for terrain collapse and subsidence in karst areas municipality of iraquara chapada diamantina ba brazil the morphological evolution of the karstic systems is associated with a set of physical and chemical processes triggered by the dissolution of the rocks related to percolation of groundwater and surface water which consequently open underground voids and carve out peculiar forms of relief due to environmental and geotechnical aspects this system is naturally more fragile and vulnerable than other natural systems and therefore has increasingly received the attention of the scientific community over the past decades the objective of the study was to delimit zones with varying degrees of susceptibility for collapses and subsidence of sinkholes in the municipality of iraquara chapada diamantina ba brazil and to understand their geological and morphological determinant factors geological data karst phenomenon map and visual analysis in the field were used to categorize zones with different types of susceptibilities to the nucleation of new sinkholes based on a hazard index this index was defined from the sum of geological hazard factors lineament density and sinkhole density the areas that presented the highest susceptibility for terrain collapse and subsidence corresponded to regions where carbonate rocks outcrop with high density of photolineaments and 2 62 sinkholes km2 processes associated with terrain collapse and subsidence in karst areas consisted of a combination of various factors hindering precise predictions however zones of different types of susceptibilities to terrain collapse and subsidence can be delimited when the relationships between these processes and their factors are understood the hazard index proposed does not provide quantitative values for the probability of hazard susceptibility but rather indicates areas that are more susceptible to terrain subsidence and collapse

beginning of melting in the granite system qz or ab an h2o the beginning of melting in the system qz or ab an h2 o was experimentally reversed in the pressure range p text h text 2 text o 2 15 kbar using starting materials made up of mixtures of quartz and synthetic feldspars with increasing pressure the melting temperature decreases from 690 c at 2 kbar to 630 c at 17 kbar in the an free alkalifeldspar granite system qz or ab h2o in the granite system qz or ab an h2o the increase of the solidus temperature with increasing an content is only very small in comparison to the alkalifeldspar granite system the solidus temperature increases by 3 c 7 c if albite is replaced by plagioclase an 20 an 40 the difference between the solidus temperatures of the alkalifeldspar granite system and of quartz anorthite sanidine assemblages system qz or an h2o is approximately 50 c

sinkholes collapse structures and large landslides in an active salt dome submerged by a reservoir the unique case of the ambal ridge in the karun river zagros mountains iran abstract ambal ridge covering 4 km2 is a salt pillow of gachsaran formation with significant salt exposures in direct contact with the karun river zagros mountains the highly cavernous salt dome is currently being flooded by the gotvand reservoir second largest in iran geomorphic evidence including the sharp deflection of the karun river and defeated streams indicate that ambal is an active halokinetic structure probably driven by erosional unloading around 30 of the salt dome is affected by large landslides up to ca 50 106 m3 in volume slope oversteepening related to fluvial erosion and halokinetic rise seems to be the main controlling factor a total of 693 sinkholes have been inventoried 170 sinkholes km2 for which a scaling relationship has been produced the depressions occur preferentially along a belt with a high degree of clustering this spatial distribution is controlled by the proximity to the river slope gradient and halite content in the bedrock a large compound depression whose bottom lies below the normal maximum level of the reservoir will likely be flooded by water table rise forming a lake the impoundment of the reservoir has induced peculiar collapse structures 220 280 m across expressed by systems of arcuate fissures and scarps rapid subsurface salt dissolution is expected to generate and reactivate a large number of sinkholes and may reactivate landslides with a significant vertical component due to lack of basal support

sinkhole formation above underground limestone quarries a case study in south limburg belgium abstract historical records were used for the compilation of a database of sinkholes resulted from collapses of abandoned shallow underground limestone quarries mines in two villages in belgian south limburg during the last 350 years the formation of such sinkholes caused at least 38 casualties but more often it caused a change in topography and damage to public and private property the objective of this study is to better understand the spatial and temporal patterns of quarry collapse related sinkholes in the study area apart from sinkhole locations and ages the compiled database provides information on the dimensions of the area affected and the damage caused by sinkhole formation as well as the causal factors of sinkholes one hundred seventy three sinkholes have been reported since 1665 but most 80 reported sinkholes postdate 1965 sinkhole dimensions provided information on the type of collapse seven large sinkholes displacing a total sediment volume of 480 000 m3 resulted from large scale roof breakdown after pillar failure the smaller sinkholes were the result of fall of the overburden into galleries after local roof collapse or suffosion of a solution pipe in total these small sinkholes displaced 12 300 m3 of sediment at present almost all large underground quarries in the study area have been affected by sinkholes these features were caused by natural and anthropogenic factors and occur in zones with thin roofs where pillars were affected by pillar robbing or on locations with inappropriate sewerage systems above quarries the formation of sinkholes was often reported in spring during years with high moisture contents in the overburden caused by high groundwater recharge or above average precipitation with increasing time since quarry abandonment quarries become more susceptible to pillar creep and bending of the roof hence if no appropriate mitigation measures are taken to reduce such deterioration processes the number of sinkholes is expected to increase

investigation of sinkholes spatial distribution using the weights of evidence method and gis in the vicinity of karapinar konya turkey abstract there are many sinkholes 182 in the vicinity of karapinar approximately 20 large sinkholes 10 m in diameter were formed within the obruk plateau between 1970 and 2012 the formation of sinkholes is the most important geological hazard in the study area because they can damage engineering structures settlements agricultural areas and eventually be a source of casualties to date no study has been conducted on the distribution of sinkholes in this region in this study the spatial distribution of the sinkholes and the factors controlling sinkhole development were studied through the use of geographical information systems using a sinkhole inventory and a spatial database containing information on the topography geology hydrogeology and land use initially 182 sinkholes were identified in the area by examining the digital elevation model produced for this study the sinkholes were verified in the field thirty two factor maps were produced to investigate their relationship with sinkholes using the weights of evidence method the sinkholes are mainly related to dissolution of the neogene age lacustrine insuyu formation consisting of limestone and clayey limestone sinkhole frequency increases in the vicinity of drainages 2000 3000 m and faults

three dimensional characterization of complex mantled karst structures decision making and engineering solutions applied to a road overlying evaporite rocks in the ebro basin spain abstract at mantle cover evaporite karst settings evidences of surficial subsidence are usually strongly dependent on geomechanical properties and spatial inhomogeneities within the cover series in infrastructure assets affected by karst processes the evaluation of mitigation or engineering solutions requires a 3d reconstruction of the underground karst affected materials analysis and surveillance are also required to avoid deterioration of natural conditions and the migration or the increase in rate of karst features in the central ebro basin fluvial deposits cover soluble salts mainly gypsum located below the regional water table variations of geomechanical parameters of the cover mainly related to carbonate crusts and the contemporaneous sedimentation of fluvial deposits during karst activity can complicate the characterization of affected volumes in this work an integrated analysis including the available information 3d characterization by means of gpr and three boreholes in a peri urban road was carried out to finally define the geometry and evolution of karst phenomena an evaluation of metastable situations is also considered in order to define the zoning for hazard mitigation this evaluation shows that the volumetric affection to the cover series is in the range of tens of thousands of cubic meters a proposed list of factors related to social aspects infrastructure relevance and budget is analyzed

geodetic strain observations and return period of the strongest earthquakes of a given seismic source zone we present the basis for a method for estimating the return period of large and medium earthquakes that is independent of current deterministic and probabilistic approaches the two standard techniques of seismic hazard assessment probabilistic seismic hazard assessment psha and deterministic seismic hazard assessment dsha suffer from limited knowledge of seismic prehistory a further weakness of psha is its requirement of homogeneous seismic activity within a seismic zone moreover psha and dsha were developed for seismically active areas and thus cannot reliably be used in areas of medium and low activity in this paper we propose the combined use of geodetic strain rate data and the seismic moment data set determined for past seismic events this combination represents a new and independent approach to estimation of future seismic activity using a modified version of kostrov s phys solid earth 1 23 40 1974 equation and the catalogue of seismic moments the minimum return period of the strongest earthquakes of a source area is estimated

multidisciplinary approach for urban planning in alluvial karstic zones case study from the central ebro basin spain abstract constructive design on inhomogeneous ground often faces geotechnical problems particularly under ongoing karst processes namely subsidence or collapses careful analysis of this kind of problems by means of different techniques together with accurate geological models is needed for correct urban planning in this work the main results obtained during an urban planning study in the proximities of zaragoza city ne spain are presented several independent approaches give results that can only be clearly interpreted when integrated as a whole the first approach is related to historical geomorphological analysis from maps and series of aerial photographs the second approach is an intensive geophysical survey gpr magnetometry gravimetry em the third approach includes the analysis of subsoil characteristics by means of trenches boreholes and dynamic penetration tests prior studies failed in the correct characterization of this area mainly because of the difficulties in interpreting the obtained data the discussion of this work analyzes the sensitivity of techniques and reliability of the obtained results and the importance of correctly defining the geological geotechnical model the presented methodology responds to the main potential problems to be analyzed in complex alluvial environments linked to karst activity and can be applied in similar contexts where different approaches must be integrated to obtain realistic geological models

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 new geobarometer for the assemblage biotite muscovite chlorite quartz the equilibrium thermodynamics of the reaction 4kmga1si40 o oh mg5a1 si30 o oh muscovlte chlorite muscovite biotite ka13si 0 oh 3kmg3aisi 0 0 oh 7si0 4h o quartz fluid can be formulated as a geobarometer thermo dynamic data for the mg a1 celadonite end member of muscovite is derived from the reversed mineral equilibria experiments of velde i 965 using the calculation method of powell 1978 giving afh 1298 5823 5 kj s 1298 0 3060kjk v 1298 13 8kjkbar

changes in groundwater chemistry before two consecutive earthquakes in iceland precursor events to earthquakes are rarely reproduced measurement of groundwater chemistry in iceland between 2008 and 2013 reveals distinct changes prior to two consecutive m5 earthquakes

occurrence and origin of andalusite in peraluminous felsic igneous rocks andalusite occurs as an accessory mineral in many types of peraluminous felsic igneous rocks including rhyolites aplites granites pegmatites and anatectic migmatites some published stability curves for and sil and the water saturated granite solidus permit a small stability field for andalusite in equilibrium with felsic melts we examine 108 samples of andalusite bearing felsic rocks from more than 40 localities world wide our purpose is to determine the origin of andalusite including the t p x controls on andalusite formation using eight textural and chemical criteria size compatibility with grain sizes of igneous minerals in the same rock shape ranging from euhedral to anhedral with no simple correlation with origin state of aggregation single grains or clusters of grains association with muscovite with or without rims of monocrystalline or polycrystalline muscovite inclusions rare mineral inclusions and melt inclusions chemical composition andalusite with little significant chemical variation except in iron content 008 171 wt feo compositional zoning concentric sector patchy oscillatory zoning cryptically reflect growth conditions compositions of coexisting phases biotites with high siderophyllite eastonite contents aliv 268 007 atoms per formula unit muscovites with 057 401 wt feo and 002 285 wt tio2 and apatites with 353 018 wt f coexisting muscovite biotite pairs have a wide range of f contents and fbt 1612fms 0015 most coexisting minerals have compositions consistent with equilibration at magmatic conditions the three principal genetic types of andalusite in felsic igneous rocks are type 1 metamorphic a prograde metamorphic in thermally metamorphosed peraluminous granites b retrograde metamorphic inversion from sillimanite of unspecified origin c xenocrystic derivation from local country rocks and d restitic derivation from source regions type 2 magmatic a peritectic water undersaturated t associated with leucosomes in migmatites b peritectic water undersaturated t as reaction rims on garnet or cordierite c cotectic water undersaturated t direct crystallization from a silicate melt and d pegmatitic watersaturated t associated with aplite pegmatite contacts or pegmatitic portion alone type 3 metasomatic water saturated magma absent spatially related to structural discontinuities in host replacement of feldspar and or biotite intergrowths with quartz the great majority of our andalusite samples show one or more textural or chemical criteria suggesting a magmatic origin of the many possible controls on the formation of andalusite excess al2o3 water concentration and fluid evolution high be b li p high f high fe mn ti and kinetic considerations the two most important factors appear to be excess al2o3 and the effect of releasing water either to strip alkalis from the melt or to reduce alumina solubility in the melt of particular importance is the evidence for magmatic andalusite in granites showing no significant depression of the solidus suggesting that the and sil equilibrium must cross the granite solidus rather than lie below it magmatic andalusite however formed is susceptible to supra or sub solidus reaction to produce muscovite in many cases textural evidence of this reaction remains but in other cases muscovite may completely replace andalusite leaving little or no evidence of its former existence

parametric time series analysis of extreme events in earthquake electrical precursors abstract a statistical method to evaluate extreme events in earthquake precursory signals of electrical nature is proposed the occurrence probability of seismo electrical anomalies is computed by means of a parametric time series approach in order to avoid the influence of external noise a preliminary filtering of the electrical signals is performed in a second step an autoregressive model to describe the residual time series is suitably identified and fitted to the data finally parametric inference of extreme events is carried out on the basis of the selected model the performance of the technique has been evaluated by considering geoelectrical time series recorded by an automatic station located on the southern apennine chain italy this region was interested by the november 1980 irpinia basilicata earthquake and it is one of the most active areas of the mediterranean region finally a possible correlation between electrical anomalies and seismic events occurred in the area is discussed