hydraulic physical and rheological characteristics of rain triggered lahars at semeru volcano indonesia lahars volcanic debris flows have been responsible for 40 of all volcanic fatalities over the past century mount semeru east java indonesia is a persistently active composite volcano that threatens approximately one million people with its lahars and pyroclastic flows despite their regularity the behaviour and the propagation of these rain triggered lahars are poorly understood in situ samples were taken from lahars in motion at two sites in the curah lengkong river on the southeast flank of semeru providing estimates of the particle concentration grain size spectrum grain density and composition this enables us to identify flow sediment from three categories of lahars a hyperconcentrated flow b non cohesive clast and matrix supported debris flow and c muddy flood to understand hyperconcentrated flow sediment transport processes it is more appropriate to sample the active flows than the post event lahar deposits because in situ sampling retains the full spectrum of the grain size distribution rheometrical tests on materials sampled from moving hyperconcentrated flows were carried out using a laboratory vane rheometer despite technical difficulties results obtained on the 63 180 and 400 m fractions of the sampled sediment suggest a purely frictional behaviour importantly and contrary to previous experiments conducted with monodisperse suspensions our results do not show any transition towards a viscous behaviour for high shear rates these data provide important constraints for future physical and numerical modelling of lahar flows copyright 2010 john wiley sons ltd

sedimentary pyrite formation an update sedimentary pyrite formation during early diagenesis is a major process for controlling the oxygen level of the atmosphere and the sulfate concentration in seawater over geologic time the amount of pyrite that may form in a sediment is limited by the rates of supply of decomposable organic matter dissolved sulfate and reactive detrital iron minerals organic matter appears to be the major control on pyrite formation in normal non euxinic terrigenous marine sediments where dissolved sulfate and iron minerals are abundant by contrast pyrite formation in non marine freshwater sediments is severely limited by low concentrations of sulfate and this characteristic can be used to distinguish ancient organic rich fresh water shales from marine shales under marine euxinic conditions sufficient h2s is produced that the dominant control on pyrite formation is the availability of reactive iron minerals calculations based on a sulfur isotope model indicate that over phanerozoic time the worldwide average organic carbon to pyrite sulfur ratio of sedimentary rocks has varied considerably high cs ratios during permo carboniferous time can be explained by a shift of major organic deposition from the oceans to the land which resulted in the formation of vast coal swamps at that time low cs ratios compared to today during the early paleozoic can be explained in terms of a greater abundance of euxinic basins combined with deposition of a more reactive type of organic matter in the remaining oxygenated portions of the ocean the latter could have been due to lower oceanic oxygen levels and or a lack of transportation of refractory terrestrial organic matter to the marine environment due to the absence of vascular land plants at that time

high thermal maturity in the lower saxony basin intrusion or deep burial abstract the lower saxony basin lsb is situated at the southern rim of the northern permian basin the most important hydrocarbon bearing province in europe in its southern part areas of high thermal maturation up to 6 rr occur which were previously explained as being caused by magmatic intrusions of turonian to santonian age that affected carboniferous to lower cretaceous rocks in this area 2d numerical basin modelling was carried out in order to reconstruct the temperature histories along two parallel n s trending seismic sections along these sections new data about maturity distribution and temperature history were obtained by vitrinite reflectance measurements and apatite fission track analysis for the areas with highest maturity values low coalification gradients were established which agree well with earlier published data on wells further towards the west this new information does not support previous hypotheses on high heat flows from magmatic intrusions even if lateral heat transport is taken into account instead comparisons with a recently published map of the subsurface structure of the lsb indicate that maturity distribution may be closely related to major tectonic structures deep burial of individual structures of the lsb which are bordered by deep e w to ese wnw trending faults is further suggested by a rapidly increasing thicknesses of preserved cretaceous strata towards the south and b structural restoration of one of the seismic sections to achieve a fit between measured and calculated palaeo temperature and vitrinite reflectance data deep burial of carboniferous source rocks during cretaceous time has to be assumed due to an inversion phase in the early and middle upper cretaceous major amounts of sediment were removed and further uplift occurred in tertiary times in contrast the northern part of the lsb experienced maximum burial and temperatures during tertiary times

the influence of tectonic deformation on some geochemical properties of coals a possible indicator of outburst potential abstract nearly all outburst prone coal is known to have been tectonically deformed in fault and fold zones which underwent one or more episodes of strong structural deformation the physical properties of deformed coal such as strength coefficient and rate of gas desorption have been broadly studied and used to predict outbursts in the past however it can be difficult to reliably determine these physical coefficients from core sampling operations because the coal can be inadvertently pulverized during drilling the development of a new index which predicts the outburst potential of coal seams and is not influenced by sampling procedures could be beneficial to mining safety technology tectonic deformation may not only affect the original physical structure of a coal but also may bring about changes in chemical properties any chemical property with the potential to identify outburst prone coal must also be stable and independent of the physical changes imposed by drilling most of the chemical characteristics of coal display no obvious difference between normal undeformed coal which is not subject to outbursts and deformed coal however recent studies have shown that the chloroform extract yield is a very good geochemical index for differentiating these coals nineteen coal samples from five mines experiencing outbursts in the pingdingshan coalfield henan china were analyzed their mean maximum vitrinite reflectance in oil ranges from 0 97 to 1 28 all of the samples were prepared to 180 m 80 mesh us and subsamples were extensively extracted with chloroform in a soxhlet apparatus at 75 c the mean extract yield of the 10 deformed coals is 1 45 whereas that of the nine normal coals is 0 44 we conclude that deformed coal has a higher chloroform extract yield than equivalent coal which has not been tectonically disturbed chloroform extraction therefore can be used to recognize deformed coal and the potential to undergo further deformation chloroform extract yield is an accepted measure of the hydrocarbon generating potential of coals and other rocks the results presented here therefore suggest that tectonic deformation may modify the hydrocarbon generating potential of coals the adsorption of soluble organic matter expelled during and following tectonic deformation onto enhanced surface areas may have contributed to the higher extract yields of the deformed coal

optical characteristics of amorphous kerogens and the hydrocarbon generating potential of source rocks abstract four recurring types of amorphous kerogen are optically identified in petroleum source rock samples and are related to hydrocarbon generating potential defined here as geochemically interpreted oil prone or gas prone at this time a genetic classification is not possible the different amorphous kerogen types are distinguished on the basis of microscopic textural differences type a chunky compact masses with mottled network or weak polygonal textures type b very small dense elongate oval or rounded individual grains type c clumpswith granular fragmented or globular textures type d thin platy or rectangular individual grains geochemistry defined oil prone samples generally contain types a and or d separately or combined geochemically defined gas prone samples rarely contain type a and vary in amounts of types b c and or d the samples in this study contain dominantly one of the four types of amorphous kerogen so the geochemical analyses of the whole rock or bulk concentrated kerogen samples are assumed to be analyses of the dominant amorphous type the samples were chemically analyzed by several techniques to determine the oil or gas generating potential the establishment of relations between specific optical and chemical properties of kerogen types can make visual kerogen analyses more meaningful in predicting the hydrocarbon generation potential of source rocks

the impact of tectonic deformation upon coal seams in the south wales coalfield uk observations on the nature and appearance of coal seams which were deformed during the late carboniferous variscan orogeny have been made over several years within a number of opencast coal sites located across the south wales coalfield the deformation of coal seams was dominated by brittle failure and subsequent movement along fracture planes examination of hand specimens and smaller scale samples using a scanning electron microscope reveals the presence of two distinct types of small scale tectonic fracture markings within deformed coals striated fracture surfaces with prominent ridges and grooves can bear a superficial resemblance to shatter cones in appearance but are unique to coal in their tectonic setting and appear to have formed by static shear failure whereas strongly polished fracture surfaces result from movement across fracture planes deformed coal seams are also affected by distinctive large scale tectonic fracture sets the extent of fracturing within coal seams can be assessed using different techniques including measuring fracture frequency directly performing various strength and hardness tests making relatively simple subjective assessments on the appearance of the coal or monitoring the size distribution of the coal product by applying some of these methods within working opencast sites it can be shown that large amounts of abnormally fractured coal were formed along coal based thrust flats or detachments but that the distribution of fractured coal along detached seams is rarely homogeneous enhanced fracturing often occurred in association with the localised thickening of seams along small scale thrusts or within coal duplexes variable seam thicknesses and pockets of structurally thickened coal are seen as the most efficient means by which the presence and location of significant amounts of fractured coal can be predicted from borehole evidence during prospecting

quantifying channel development and sediment transfer following chute cutoff in a wandering gravel bed river abstract three dimensional morphological adjustment in a chute cutoff breach alluvial channel is quantified using digital elevation model dem analysis for a ca 0 7 km reach of the river coquet northumberland uk following cutoff in january 1999 channel and bar topography was surveyed using a total station on five occasions between february 1999 and december 2000 analysis of planform change coupled with dem differencing elucidates channel and barform development following cutoff and enables quantification of sediment transfers associated with morphological adjustment within the reach this exercise indicates an initial phase of bed scour followed by a period characterised by extensive bank erosion and lateral channel migration where erosion including bed scour totalled some 15 000 m3 of sediment the channel in the post cutoff disequilibrium state is highly sensitive to relatively low magnitude floods and provision of accommodation space by bank erosion encouraged extensive lateral bar development bar development was further facilitated by infilling of channels abandoned by repeated within reach avulsion and large scale aggradation of sediment lobes deposited by higher magnitude floods calculations indicate that at least 6600 m3 of sediment was deposited on emerging bars within the reach over the survey period and 2300 m3 deposited within the channel sediment losses from the reach may have exceeded 6500 m3

major and minor structural features of a bedding shear zone along a coal seam and related gas outburst pingdingshan coalfield northern china abstract a fractured coal band traditionally called a soft coal band or structurally referred to as a bedding shear zone within the wu coal seam in the pingdingshan coalfield northern china was structurally studied based on field examination and observations by reflectance microscopy and scanning electron microscopy sem the bedding shear zone is not consistent with a simple bedding fault defined by pioneering geologists but rather a complexly deformed band locally overprinted by ductile shearing fabrics dominant small scale structures within the bedding shear zone are thrusts folds cleavage duplexes and related structures but local refolded folds kink bands and s c band structures also indicate ductile shear deformation typically developed in areas of steep dip such as within the limb of a subordinate fold bed parallel shearing within the coal seam has been considered a serious influence on gas outburst in underground mining production in addition to thickening the seam and reducing the quality of coal locally abnormal thickening of a shear zone and extensive compressive structures where ductile fabrics frequently occur are closely related with the site of an outburst thickening of a shear zone increases the capacity of methane storage and compressive structures within a shear zone may act as a tectonic screen blocking methane migration which can result in a pocket of high methane pressure a potential risk of outburst is indicated as a working face approaches an area of high methane pressure three abnormal phenomena encountered during a mining operation presage methane outburst for seams with a bedding shear zone

evolution of the lower saxony basin abstract the lower saxony basin is a 300 km long and 65 km wide late jurassic and early cretaceous trough which parallels the northern margin of the rhenish massif this basin became inverted during the senonian and paleocene the lower saxony basin is the most important oil province of germany past production amounts to 200 10 6 t of oil 1 5 10 9 bbl the lower saxony basin is superimposed on the late carboniferous variscan foredeep basin and the frontal structures of the variscan fold belt during the permian to middle jurassic the area formed part of the northwest european basin differential subsidence of the lower saxony basin was initiated during the late jurassic and persisted till albian time this involved reactivation of permo carboniferous fracture systems by divergent wrenching a major aptian deep seated laccolith is evident in the western part of the lower saxony basin during the senonian and paleocene sinistral convergent wrenching induced uplift of the basin floor and folding of its sedimentary fill the margins of the inverted lower saxony basin are thrust over the adjacent stable platform areas the differential subsidence of the lower saxony basin can be related to a period of major crustal extension in the north sea rift basin inversion coincides with important orogenic events in the alpine system and is thought to have been induced by intra plate compressional stresses

a thin skinned thrust model for variscan pembrokeshire wales abstract the east and west coasts of pembrokeshire sw wales provide two sections through the variscan fold and thrust belt the evolution of these structures is interpreted in terms of a thin skinned tectonic model balanced cross sections are constructed for the high level imbricate sequences and these allow reasonably accurate estimates of shortening to be made basement control on structures developed in the upper carboniferous cover rocks is minimal though some thrust ramp positions may be determined by the location of earlier normal faults the thrust belt may be divided into two parts according to the depth to the decollement horizon in the north imbricate fans developed from a shallow level detachment shortening is heterogeneous and both thrust periodicity and fold style are partly determined by rheology cumulative tectonic displacement increases to the west across pembrokeshire resulting in a net clockwise rotation of about 40

occurrence and origin of ultralaminar structures in amorphous kerogens of various source rocks and oil shales abstract forty low maturity type i ii kerogens from source rocks and oil shales ranging in age from infra cambrian to miocene were examined by transmission electron microscopy tem when previously observed by light microscopy and or uv fluorescence microscopy the above samples like a very large number of kerogens seemed homogeneous and amorphous in fact tem revealed the presence of ultralaminar structures in 22 of these amorphous kerogens the abundance of ultralaminae depends on the considered sample and some of the tested kerogens are nearly exclusively composed of ultralamina accumulations based on thickness three main groups of ultralaminae can be identified parallel studies on extant algae indicated that some of the above ultralaminae likely derived from the resistant outer walls of microalgae the fossilization of such outer walls should occur via the selective preservation pathway and result in the formation of highly aliphatic ultralaminar kerogens the lack of ultralaminae in infra cambrian kerogens is consistent with a cyanobacterial origin

debris flow evolution and the activation of an explosive hydrothermal system te maari tongariro new zealand abstract analysis of the pre and post eruption topography together with observations of the avalanche deposition sequence yields a triggering mechanism for the 6 august 2012 eruption of upper te maari the avalanche was composed of a wedge of c 683 000 774 000 m 3 of coarse breccia spatter and clay rich tuffs and diamictons which slid from the western flanks of the upper te maari crater the failure plane is considered to be a hydrothermally altered clay layer this landslide led to a pressure drop of up to 0 5 mpa enough to generate an explosive eruption from the hydrothermal system below which had been activated over the months earlier by additional heat and gas from a shallow intrusion the landslide transformed after c 700 m into a clay rich cohesive debris flow eroding soils from steep narrow stretches of channel before depositing on intermediate broad flatter reaches after each erosive reach the debris flow contained greater clay and mud contents and became more mobile at c 2 km flow distance however the unsaturated flow stopped due to a lack of excess pore pressure this volume controlled flow deposited thick steep sided lobes behind an outer levee accreting inward and upward to form a series of curved surface ridges

geomorphic effects flood power and channel competence of a catastrophic flood in confined and unconfined reaches of the upper lockyer valley southeast queensland australia flooding is a persistent natural hazard and even modest changes in future climate are believed to lead to large increases in flood magnitude previous studies of extreme floods have reported a range of geomorphic responses from negligible change to catastrophic channel change this paper provides an assessment of the geomorphic effects of a rare high magnitude event that occurred in the lockyer valley southeast queensland in january 2011 the average return interval of the resulting flood was similar to 2000 years in the upper catchment and decreased to similar to 30 years downstream a multitemporal lidar derived dem of difference dod is used to quantify morphological change in two study reaches with contrasting valley settings confined and unconfined differences in geomorphic response between reaches are examined in the context of changes in flood power channel competence and degree of valley confinement using a combination of one dimensional 1 d and two dimensional 2 d hydraulic modelling flood power peaked at 9800 w m 2 along the confined reach and was 2 3 times lower along the unconfined reach results from the dod confirm that the confined reach was net erosional exporting similar to 287 000 m 3 of sediment whilst the unconfined reach was net depositional gaining similar to 209 000 m 3 of sediment 70 of the amount exported from the upstream confined reach the major sources of eroded sediment in the confined reach were within channel benches and macrochannel banks resulting in a significant increase of channel width in the unconfined reach the benches and floodplains were the major loci for deposition whilst the inner channel exhibited minor width increases the presence of high stream power values and resultant high erosion rates within the confined reach is a function of the higher energy gradient of the steeper channel that is associated with knickpoint development dramatic differences in geomorphic responses were observed between the two adjacent reaches of contrasting valley configuration the confined reach experienced large scale erosion and reorganisation of the channel morphology that resulted in significantly different areal representations of the five geomorphic features classified in this study c 2013 elsevier b v all rights reserved

experimental insights on geomorphological processes within dam break outburst floods summary hydraulic behavior and unsteady sediment transport within dam break outburst floods are inherently inter dependent yet poorly constrained this study experimentally determined how the mobility and clast size of channel bed sediments affected the peak flow depth and flow velocities wave propagation and attenuation sediment entrainment and duration of transport flood power energy transfer and geomorphological impact of outburst floods due to our choice of clast size and of a unimodal size distribution the predominant sediment transport mechanism was bedload we found that frontal wave propagation was slower and attenuated faster for flows over a mobile bed versus those over a fixed bed peak flow depth was greater and was attained earlier for flows over a mobile bed and with increased clast size geomorphological power declined logarithmically with time after an initial period where gravitational forces exceeded frictional forces both peak and time to peak geomorphological power varied inversely with clast size peak deposition rates were greatest with coarser bed sediment but time to peak deposition rate was inversely proportional to clast size volume changes down channel were described by an exponential curve which we suggest indicates that sediment transport proceeded in waves via both translation and dispersion mechanisms peak suspended load occurred coincident with peak flow velocity peak bedload occurred coincident with peak flow depth and peak sediment discharge lagged behind peak water discharge these descriptions of kinematic transformation multi phase flow and of geomorphological work due to outburst floods help to provide data for numerical modelling for mitigating outburst flood hazards and for informing on the immediate and longer term geological legacy of outburst floods

studying monogenetic volcanoes with a terrestrial laser scanner case study at croscat volcano garrotxa volcanic field spain erosional processes natural or anthropogenic may partly destroy the relatively small sized volcanic edifices characteristic of monogenetic volcanic zones leaving their internal structure well exposed nevertheless the study of these outcrops may be extremely challenging due to restricted accessibility or safety issues digital representations of the outcrop surface have been lately used to overcome such difficulties data acquired with terrestrial laser scanning instruments using light detection and ranging technology enables the construction of such digital outcrops the obtained high precision 3 d terrain models are of greater coverage and accuracy than conventional methods and when taken at different times allow description of geological processes in time and space despite its intrinsic advantages and the proven satisfactory results this technique has been little applied in volcanology related studies here we want to introduce it to the volcanological community together with a new and user friendly digital outcrop analysis methodology for inexperienced users this tool may be useful not only for volcano monitoring purposes but also to describe the internal structure of exposed volcanic edifices or to estimate outcrop erosion rates that may be helpful in terms of hazard assessment or preservation of volcanic landscapes we apply it to the croscat volcano a monogenetic cone in the la garrotxa volcanic field catalan volcanic zone ne spain quarrying of which leads to a perfect view of its interior but restricts access to its uppermost parts croscat is additionally one of the most emblematic symbols of the la garrotxa volcanic field natural park and its preservation is a main target of the park administration

a depositional model for the mid westphalian a to late westphalian b coal measures of south wales mid westphalian a to late westphalian b sediments of the south wales coalfield comprise mainly lacustrine raised mire and flood deposits developed in an upper coastal plain environment occasional high sinuosity fine grained channel systems drained the subdued topography of the wales brabant massif to the north and east of the basin low sinuosity channels with lithic coarse grained fills drained a rising source to the south direct marine influence was restricted to a single marine band facies distributions were controlled by 1 local scale 10 2 10 3 m 2 autocyclic sedimentary processes 2 regional scale 10 km 2 synsedimentary fault activity and differential subsidence and 3 basin wide scale 10 2 km 2 response to changes in relative sea level base level changes are recorded by basin wide bivalve horizons up dip or landward extension of marine bands developed in lacustrine mudstones above basin wide coal seams peat accumulation was terminated by a water table rise related to base level rise following flooding re establishment of the clastic supply resulted in the gradual infilling of the basin wide lake to produce coarsening upwards cyclothems or parasequences a eustatic origin for parasequence development is supported by the development of identical facies associations and parasequences in coeval sediments from the pennine and midland valley coalfields

hazardous processes and events from glacier and permafrost areas lessons from the chilean and argentinean andes glacier and permafrost hazards such as glacial lake outburst floods and rock ice avalanches cause significant socio economic damages worldwide and these processes may increase in frequency and magnitude if the atmospheric temperature rises in the extratropical andes nearly 200 human deaths were linked to these processes during the twentieth century we analysed bibliographical sources and satellite images to document the glacier and permafrost dynamics that have caused socio economic damages in this region in historic time including glacial lake outburst floods ice and rock ice avalanches and lahars to unravel their causes and geomorphological impacts in the extratropical andes at least 15 ice dammed lakes and 16 moraine dammed lakes have failed since the eighteenth century causing dozens of floods some floods rank amongst the largest events ever recorded 5000 106 m3 and 229 106 m3 respectively outburst flood frequency has increased in the last three decades partially as a consequence of long term decades to centuries climatic changes glaciers shrinkage and lake growth short term days to weeks meteorological conditions i e intense and or prolonged rainfall and high temperature that increased meltwater production have also triggered outburst floods and mass movements enormous mass failures of glaciers and permafrost 10 106 m3 have impacted lakes glaciers and snow covered valleys initiating chain reactions that have ultimately resulted in lake tsunamis and far reaching 50 km flows the eruption of ice covered volcanoes has also caused dozens of damaging lahars with volumes up to 45 106 m3 despite the importance of these events basic information about their occurrence e g date causes and geomorphological impact which is well established in other mountain ranges is absent in the extratropical andes a better knowledge of the processes involved can help to forecast and mitigate these events copyright 2014 john wiley sons ltd

evaluation of titan2d modelling forecasts for the 2007 crater lake break out lahar mt ruapehu new zealand abstract following the 1995 1996 eruptions of mt ruapehu the hazard of a dam breakout lahar was immediately recognised because an unstable 7 9 m pile of volcaniclastic ejecta had accumulated over the former stable outlet of the normally 10 106 m3 crater lake prior to the dam breakout lahar of 18 march 2007 a range of flow scenarios down the eastern flanks of mt ruapehu were simulated using the titan2d mass flow numerical code to forecast flow travel times and inundation areas titan2d is a depth averaged code that solves the movement of a granular or two phase mass over digital representations of natural terrains we compared modelled scenarios run before the 18 march 2007 break out lahar of ruapehu to details from the actual event the titan2d models were accurate in predicting both the inundation areas and travel times of the lahar at various key points down the volcano s flanks to 9 km beyond 9 km and a major break in slope the initial model parameters did not cope with the fundamental change that occurred in flow rheology velocity and discharge predicted at a lahar deflection structure the bund at 9 km from the lake were up to 20 less than those of the actual 2007 flow but matched closely those of the largest 1995 lahar at this location predicted paths of flow including sites of avulsion correlated well with those in the march 2007 event in addition the simulations predicted dynamic behaviour such as super elevation of flow in corners and hydraulic ponding that corresponds to real event measurements this application shows that the titan2d model can be used to reliably forecast certain parameters of lahar flow however care must be taken when choosing parameters and flow length scales over which the comparison should be made

localized and distributed erosion triggered by the 2015 hurricane patricia investigated by repeated drone surveys and time lapse cameras at volcan de colima mexico abstract in october 2015 patricia a major category 5 hurricane made landfall in western mexico resulting in 500 mm cumulated rainfall and lahar generation along the southerly directed montegrande valley of volcan de colima we monitored lahar deposition and erosion using time lapse trail cameras and conducted repeated camera drone overflights two days before and after the hurricane using photogrammetric processing we derive a unique dataset of high resolution digital terrain models and study the geomorphologic impacts of a single lahar event results reveal different types of erosion at 8 km distance from the volcano with overland flow and rill networks developing into major erosion gullies exceeding a depth of 4 m as well as bank collapse oversteepening and marginal erosion we find alternating deposition and erosion zones that depend on general slope and valley width and find that the overland flow related erosion is an important contributor to the bulking process of lahars moreover this study shows that camera monitoring is very useful for studying the relationship between volcano landscape evolution and hydrometeorological extremes and for rapid assessment associated with single lahar events

influence of particle and surface quality on the vitrinite reflectance of dispersed organic matter comparative exercise using data from the qualifying system for reflectance analysis working group of iccp the development of a qualifying system for reflectance analysis has been the scope of a working group within the international committee for coal and organic petrology iccp since 1999 when j koch presented a system to qualify vitrinite particles according to their size proximity to bright components and homogeneity of the surface after some years of work aimed at improving the classification system using photomicrographs it was decided to run a round robin exercise on microscopy samples the classification system tested consists of three qualifiers ranging from excellent to low quality vitrinites with an additional option for unsuitable vitrinites this paper reports on the results obtained by 22 analysts who were asked to measure random reflectance readings on vitrinite particles assigning to each reading a qualifier four samples containing different organic matter types and a variety of vitrinite occurrences have been analysed results indicated that the reflectance of particles classified as excellent good or poor compared to the total average reflectance did not show trends to be systematically lower or higher for the four samples analysed the differences in reflectance between the qualifiers for any given sample were lower than the scatter of vitrinite reflectance among participants overall satisfactory results were obtained in determining the reflectance of vitrinite in the four samples analysed this was so for samples having abundant and easy to identify vitrinites higher plant derived organic matter as well as for samples with scarce and difficult to identify particles samples with dominant marine derived organic matter the highest discrepancies were found for the organic rich oil shales where the selection of the vitrinite population to measure proved to be particularly difficult special instructions should be provided for the analysis of this sort of samples the certainty of identification of the vitrinite associated with the vitrinite reflectance values reported has been assessed through a reliability index which takes into account the number of readings and the coefficient of variation the same statistical approach as that followed in the iccp vitrinite reflectance accreditation program for single seam coals has been used for data evaluation the results indicated low to medium dispersion for 17 out of 22 participants this combined with data from other sets of comparative analyses over a long period is considered an encouraging result for the establishment of an accreditation program on vitrinite reflectance measurements in dispersed organic matter

monitoring and modelling morphological change in a braided gravel bed river using high resolution gps based survey recent research in fluvial geomorphology has emphasized the direct monitoring of channel topography as a useful tool to better understand the interrelationship between river form and process and in particular to estimate bedload transport rates and reach scale sediment budgets until recently however this morphometric approach has been limited to comparison of repeatedly surveyed cross sections with the associated problems of low frequency sampling and an emphasis on cross stream as opposed to downstream morphological dynamics recent advances in analytical photogrammetry have however permitted the acquisition of data at sufficient resolutions to represent macroform 101 m and microform 10 m channel geometry in fully three dimensions while inherently spatially distributed the photogrammetric approach to land surveying is however restricted to observable areas of the channel and is thus of limited use in the subaqueous zone especially if flows are turbid or highly coloured this paper presents an alternative approach to the study of three dimensional morphological dynamics of a divided reach of the gravelly river feshie scotland in which topographic survey of both exposed and submerged areas of the reach was undertaken using the global positioning system gps survey results from two field programmes in 1998 and 1999 are presented in which a geotronics geotracer 2000 real time kinematic gps receiving unit was used to survey a 200 80 m reach rapid radial survey methods were employed permitting the collection of 2000 survey points per day giving a mean density over the 13 ha reach of 1 1 points per square metre a detailed assessment of survey errors and dem quality is presented and a limit of detection of c 10 cm proposed as an upper threshold for the identification of significant change between dems preliminary interpretation of channel dynamics in 1998 99 reveals relatively little change to the overall macroscale reach structure dem differencing techniques however highlight important local changes including the progradation of submerged bar fronts bar head aggradation and scour along major channel thalwegs and the erosion of fines from sloughs copyright 2000 john wiley sons ltd

quantifying the geomorphic impacts of a lake breakout lahar mount ruapehu new zealand at 11 18 h new zealand time gmt 12 on 18 march 2007 an impoundment of 0 01 10 6 m 3 of tephra collapsed releasing 1 3 10 6 m 3 of water from crater lake at 2536 m elevation on mount ruapehu the lahar traveled 200 km along the whangaehu river aerial lidar surveys of the upper 62 km of flow path were made before and after the lahar we present here the first large scale quantification of the geomorphic impact of the dam break flood along with the rates and controls on its sediment entrainment and deposition the flood mobilized a net value of 2 5 3 1 10 6 m 3 of boulders gravel and sand over the first 5 km of travel to form a lahar of at least 4 4 10 6 m 3 passing instruments at 6 9 km lidar volume transfer calculations match dynamic measurements made after a logarithmic increase in cumulative net sediment entrainment the lahar appeared to reach its maximum sediment carrying capacity at 22 km patterns of alternating sediment erosion and deposition occurred that dominantly reflect a combination of channel morphology and confinement on the local sediment carrying capacity of the flow

outburst flood evolution at russell glacier western greenland effects of a bedrock channel cascade with intermediary lakes abstract glacial lake outburst floods have produced a distinctive and widespread quaternary record both onshore and offshore via widespread and intense geomorphological impacts yet these impacts remain poorly understood due to a lack of modern analogues this study therefore makes a systematic quantification of the evolution of a bedrock channelled outburst flood channel topography was obtained from digitised aerial photographs a 5 m grid resolution dem and bathymetric surveys flood inundation was measured in the field from dgps measurements flood evolution was analysed with application of a numerical model novel flood metrics including rate of rise to peak and persistence above a value of hydraulics were calculated the key findings were that outburst floods i that enter intermediary lakes are dramatically attenuated in terms of propagation whilst basin filling proceeds to the outlet level dissipated of energy due to considerable flow recirculation during the rising stage of the flood and after overtopping of the outlet are moderated in terms of peak discharge ii can have kinematic waves that are introduced to a flood via hydraulic ponding iii may develop a partitioning of flow regimes for instantaneous peak discharge bed shear stress and froude number due to time transgressive changes in channel cross section specifically between inner channel and overbank regions furthermore normalised change in cross sectional area and normalised change in channel slope can be used to suggest the relative magnitude of instantaneous peak discharge net erosion along a reach can be related to hydraulic persistence above a marker value and net deposition can be related to a time to peak value reconstructions of quaternary outburst floods should consider the importance of including intermediary lakes modern hazard mitigation studies could usefully note the potential use of reservoirs as an outburst flood alleviation resource

constraining coalbed methane reservoir petrophysical and mechanical properties through a new coal structure index in the southern qinshui basin northern china implications for hydraulic fracturing structurally deformed coal sdc influences not only gas outbursts during coal mining but also coalbed methane cbm production different sdcs have different mechanical strengths and physical properties the structurally constrained petrophysical and mechanical properties of a cbm reservoir from the southern qinshui basin sqb northern china have been investigated by using a coal structure index csi the csi was established as a quantitative criterion for the deformation of sdcs based on surface conditions and blockiness using the data of 783 coring samples from 109 cbm wells the results show that undeformed coal and slight brittle sdcs are dominant in the sqb with ductile sdcs distributed locally both compressive strength and tensile strength decline exponentially with increasing csi average avg coal structure is a crucial factor for coal seam fracturing with an increasing csi avg the major fracture length will first increase to the maximum of 266 m at a csi avg of 45 and then decrease rapidly however branch fractures are independent of the csi avg the major fracture height attained a minimum of 4 39 m at a csi avg of 40 and then slowly increased therefore slightly brittle sdcs should be beneficial for fracturing at least for high rank coals the presence of variable sdcs can have a considerable impact on cbm reservoir petrophysical and mechanical properties finally a csi model that strives to establish the relation between structure deformation and cbm reservoir physical and mechanical properties in coal is expected to effectively guide hydraulic fracturing

the anatomy of a lahar deciphering the 15th september 2012 lahar at volcan de colima mexico abstract volcan de colima is one of the most active volcanoes in mexico where lahars are a common phenomenon since the reactivation of the volcanic activity in 1991 lahars have become more frequent during the june october rainy season in this region therefore volcan de colima represents a natural laboratory ideal for the constant monitoring of lahars and to study factors controlling their origin flow transport and deposition since 2007 the systematic detection of lahars in volcan de colima has been carried out using seismic data from the broadband stations of the resco network the seismological network of colima university along with three rain gauge stations located on the southern ravines of the volcano in 2011 a new monitoring station was built at 2000 m a s l along the montegrande ravine which consists of a geophone a video camera and a rain gauge station coupled with a moisture sensor transmitting in real time to the resco facilities at colima university with all the instrumentation currently installed on the volcano flanks we could monitor and describe the lahar that occurred on 15 th september 2012 along the montegrande ravine and correlate the monitoring data with information gathered by the field campaign conducted two days after the event the high quality of collected data enabled us to describe the anatomy of this lahar the event consisted of a lahar that lasted 40 min triggered by 20 mm of accumulated rainfall with a maximum intensity of 95 mm h the lahar was characterized by three main surges at 4 5 minute intervals that formed an 80 cm thick terrace the first surge was a debris flow with a block rich front followed by the main body that progressively diluted to a hyperconcentrated flow from which a 40 cm thick massive unit was emplaced 33 wt gravel and 60 wt of sand it was followed by a more dilute hyperconcentrated flow that left a massive 10 cm thick sandy layer 80 wt of sand the third surge deposited a 30 cm thick upper massive unit texturally similar to the first laminated layers separate the two first units subsequent surges were confined to the inner portion of the channel by the newly formed terrace based on flow depth estimation and difference in arrival times between geophones a mean velocity of 3 m s and a maximum peak discharge of 48 m 3 s were estimated segregation processes that promote the upwelling of the largest clasts 20 30 cm on the flow surface were also observed resulting in a clast rich levee on top of the depositional units a sedimentation rate of 5 7 cm min was also determined the results here obtained are useful to better understand textural features of lahar deposits from which important information on flow behavior can be interpreted

effects of riparian vegetation on topographic change during a large flood event rio puerco new mexico usa 1 the spatial distribution of riparian vegetation can strongly influence the geomorphic evolution of dryland rivers during large floods we present the results of an airborne lidar differencing study that quantifies the topographic change that occurred along a 12 km reach of the lower rio puerco new mexico during an extreme event in 2006 extensive erosion of the channel banks took place immediately upstream of the study area where tamarisk and sandbar willow had been removed within the densely vegetated study reach we measure a net volumetric change of 578 050 490 000 m3 with 88 3 of the total aggradation occurring along the floodplain and channel and 76 7 of the erosion focusing on the vertical valley walls the sediment derived from the devegetated reach deposited within the first 3 6 km of the study area with depth decaying exponentially with distance downstream elsewhere floodplain sediments were primarily sourced from the erosion of valley walls superimposed on this pattern are the effects of vegetation and valley morphology on sediment transport sediment thickness is seen to be uniform among sandbar willows and highly variable within tamarisk groves these reach scale patterns of sedimentation observed in the lidar differencing likely reflect complex interactions of vegetation flow and sediment at the scale of patches to individual plants

surface height adjustments in pyroclastic flow deposits observed at unzen volcano by jers 1 sar interferometry abstract pyroclastic flows from the 1990 1995 eruption of unzen a dacitic volcano in the southwest of japan descended the mountain along a variety of routes causing widespread damage and loss of life interferograms constructed from jers 1 l band synthetic aperture radar sar images show a number of features related to these pyroclastic flows and their secondary effects the most useful interferogram in this respect is based on images acquired on 22 july 1993 and 1 december 1993 and shows the descent paths for pyroclastic flows occurring in four valley systems within this time window as zones of decorrelation caused by the repeated resurfacing the 22 july 1993 sar image was through considerable good fortune acquired only 2 6 days after a major pyroclastic flow had descended into the mizunashi valley so that in the absence of rainfall the fresh 2 m thick deposits were dry when first imaged the largest differential surface height changes observed in the interferogram represent height decreases in the vertical of 12 cm and significantly lie within a small region of the mizunashi valley which was resurfaced by the pyroclastic flow of 19 july 1993 but not subsequently within this small region radar coherence is higher maximum correlation value of 0 75 in a center valley site where ash but relatively few large boulders are present in a qualitative sense the new ash surfaces exhibit higher levels of radar coherence than the older pre 19 july deposits in other unzen valleys visited by pyroclastic flows smaller differential surface height decreases 4 cm are observed where the surface deposits were emplaced by events taking place between 1 3 months before the acquisition date of the 22 july 1993 image the extra 8 cm of surface height decrease observed in the case of the freshly laid mizunashi deposits must result from a deflationary mechanism or mechanisms operating in a spatially uniform manner in order for radar coherence to be maintained a number of possible causative mechanisms including hydroconsolidation initiated by the seepage of rainwater into a newly deposited ash sheet deflation on gas release basal erosion settlement and substrate relaxation are discussed here given the relatively low emplacement temperatures of the unzen ash 300 500 c it is unlikely that viscous deformation within the body of the fresh ash deposits is responsible for the subsidence comparison of the 22 july 1993 1 december 1993 interferogram with a landsat 4 thematic mapper image of unzen acquired on 10 january 1994 highlights a ribbon like zone of radar decorrelation running along the course of the mizunashi valley which marks the path of debris flows that occurred within the time interval between the two sar images used in the construction of the interferogram overall these results demonstrate the utility of interferometric sar derived surface height and coherence measurements for monitoring the pyroclastic and debris flow regimes of active volcanoes

stability assessment of the crater lake te wai ā moe overflow channel at mt ruapehu new zealand and implications for volcanic lake break out triggers abstract the presence of lakes on active volcanoes gives rise to several unique volcano hydrologic hazards including those directly related to volcanic activity e g phreatic explosions and non volcanic phenomena e g lake outbursts mt ruapehu volcano hosts the 107 m3 crater lake te wai moe in the active summit crater making it prone to lahars due to the abundance of water stored at high elevation apart from eruptive periods when water is commonly ejected from the lake large lahar events can occur when portions of the crater rim fail during quiescent periods leading to partial lake drainage the latter occurred recently in 1953 and 2007 here we investigate the potential of future lahars due to rim failure at the current overflow channel considering several triggering scenarios during non eruptive periods the geomechanical properties of a matrix dominated breccia unit composing part of the overflow channel were analyzed using physical and mechanical laboratory methods these properties combined with previous geomechanical studies of lava units in the overflow channel were used in finite element and limit equilibrium method based groundwater and stability models groundwater models indicate that a low permeability barrier inside the crater rim is preventing water from seeping through the unconsolidated and potentially permeable breccia unit of the overflow channel the removal of this barrier or weathering of a resistive lava cap could cause water to seep through the overflow channel elevating the potential of collapse slope stability models indicate that under certain conditions the overflow channel is below a conservative threshold of stability and can be destabilized with continued mechanical or chemical weathering that reduces strength properties this is also true during high magnitude tectonic or volcanic earthquakes where large ground accelerations could result in several centimeters of displacement at the overflow channel corresponding to high hazard categories of stability in the worst case scenario modeled here full collapse of the overflow channel could result in the release of c 2 4 million m3 of lake water this could drive a lahar substantially larger than well documented historic events including the more common lahars produced during eruptions the identification of key factors affecting stability can be used to inform future monitoring and the risk of these high impact events

the role of multiple glacier outburst floods in proglacial landscape evolution the 2010 eyjafjallajokull eruption iceland the 2010 eyjafjallajokull eruption in iceland provided a unique opportunity to quantify the evolution of proglacial geomorphology during a series of volcanogenic jokulhlaups glacial outburst floods 140 events time lapse imagery and repeat terrestrial laser scans before and directly after the eruption show that the jokulhlaup of 14 april 2010 composed 61 of the 57 106 m3 total discharge of the combined events and had the highest peak discharge for the two main flood events but only deposited 18 of the total volume of sediment in front of gigjokull glacier the majority of sediments 67 of a total volume of 17 12 106 m3 were deposited by the 15 april 2010 jokulhlaup and this was followed by extensive reworking by a series of smaller jokulhlaups over the following 29 days that deposited 15 of the total sediment the geomorphological and sedimentary signatures of the two largest jokulhlaups associated with the onset of the eruption have either been reworked by later floods or are buried by later flood deposits consequently the ice proximal posteruption landscape cannot be used to reconstruct the characteristics or magnitudes of either of the two largest jokulhlaups the findings support a complex response model in which peak discharge and the bulk of the sediment transported is decoupled by changing routing mechanisms and water sediment ratios during the eruption

moraine dam breach and glacial lake outburst flood generation by physical and numerical models summary the areas of glacial lakes in the himalayas continue to increase alarmingly due to global warming with consequent risk of glacial lake outburst flood glof the outburst is most common for moraine dammed lakes as a result of a failure of the dam by overtopping and erosion or piping due to seepage in the present context glof events especially for the moraine dam failure process needs to be predicted to assess the drastic and detrimental impacts on the downstream river valley this study focuses on validating an integrated model for simulating the failure of moraine dam by overtopping and erosion using a coupled numerical simulation model the proposed numerical methodology is validated with the data from experiments in laboratory scale physical models the results of the model are compared for both the erosional profiles during collapse of the dam and the resulting outflowing flood hydrograph the primary finding is that the moraine dam height and the volume of the lake upstream of the dam are the most sensitive parameters influencing the glof peak the model is also applied to the field problem of the tangjiashan lake outburst and dam failure and shows reasonably good agreement with observations the validated model is also run for the south lhonak glacial lake in the sikkim himalayas india to obtain the probable flood hydrograph in case of failure of the moraine dam

modelling outburst floods from moraine dammed glacial lakes in response to climatic change the size and number of moraine dammed supraglacial and proglacial lake systems have increased dramatically in recent decades given an appropriate trigger the natural moraine dams that impound these proglacial lakes are breached producing catastrophic glacial lake outburst floods glofs these floods are highly complex phenomena with flood characteristics controlled in the first instance by the style of breach formation downstream glofs typically exhibit transient often non newtonian fluid dynamics as a result of high rates of sediment entrainment from the dam structure and channel boundaries combined these characteristics introduce numerous modelling challenges in this review the historical contemporary and emerging approaches available to model the individual stages or components of a glof event are introduced and discussed a number of methods exist to model the stages of a glof event dam breach models can be categorised as being empirical analytical or numerical in nature with each method having significant advantages and shortcomings empirical relationships that produce estimates of peak discharge and time to peak are straightforward to implement but the applicability of these models is often limited by the nature of the case study data from which they are derived furthermore empirical models neglect the inclusion of basic hydraulic principles that describe the mechanics of breach formation analytical or parametric models simulate breach development using simplified versions of the physically based equations that describe breach enlargement whilst complex physically based codes represent the state of the art in numerical dam breach modelling to date few of the latter have been applied to investigate the moraine dam failure problem despite significant advances in the physical complexity and availability of higher order hydrodynamic solvers the majority of published accounts that have attempted to reconstruct or predict glof characteristics have been limited often by necessity to the use of relatively simplistic models this is in part attributable to the unavailability of terrain models of many high mountain catchments at the fine spatial resolutions required for the effective application of numerically sophisticated codes and their proprietary and often cost prohibitive nature however advanced models are experiencing increasing use in the glacial hazards literature in particular the suitability of emerging mesh free particle based methods for simulating dam breach and glof routing may represent a solution to many of the challenges associated with modelling this complex phenomenon sources of uncertainty in the glof modelling chain have been identified by various workers however to date their significance for the robustness of reconstructive and predictive modelling efforts have been largely unexplored and quantified in detail these sources include the geometric and material characterisation of moraine dam complexes including lake bathymetry and the presence and extent of buried ice initial conditions freeboard precise spillway dimensions spatial discretisation of the down valley domain hydrodynamic model dimensionality and the dynamic coupling of successive components in the glof model cascade

geomorphological evolution of a fluvial channel after primary lahar deposition huiloac gorge popocatepetl volcano mexico abstract popocatepetl volcano 19 02 n 98 62 w 5424 m began its most recent period of volcanic activity in december 1994 the interaction of volcanic and glacier activity triggered the formation of lahars through the huiloac gorge located on the northern flank of the volcano causing significant morphological changes in the channel the most powerful lahars occurred in april 1995 july 1997 and january 2001 and were followed by secondary lahars that formed during the post eruptive period this study interprets the geomorphological evolution of the huiloac gorge after the january 2001 lahar variations in channel morphology at a 520 m long research site located mid way down the gorge were recorded over a 4 year period from february 2002 to march 2005 and depicted in five geomorphological maps scale 1 200 for 14 february and 15 october 2002 27 september 2003 9 february 2004 and 16 march 2006 a gis was used to calculate the surface area for the landforms identified for each map and detected changes and erosion deposition processes of the landforms using the overlay function for different dates findings reveal that secondary lahars and others types of flows like sediment laden or muddy streamflows caused by precipitation rapidly modified the gorge channel following the january 2001 non eruptive lahar a period associated with volcanic inactivity and the disappearance of the glacier once located at the headwall of the gorge field observations also confirmed that secondary flows altered the dynamics and geomorphological development of the channel these flows incised and destroyed the formations generated by the primary lahars 1997 and 2001 causing a widening of the channel that continues today after february 2004 a rain triggered lahar and other flows infilled the channel with materials transported by these flows the deposits on the lateral edges of the channel form terraces a recent lull in lahar activity contrasts with the increasing instability of the edges of the channel and the continuous edification and destruction of recent lahar terraces

variscan compressional structures within the main productive coal bearing strata of south wales the structure of the main productive coal measures within the anthracite zone in the western part of the south wales coalfield is re examined using data from recently operational opencast coal sites variscan thrusts and or folds and bed parallel shear structures are present within all of the sites studied at east pit unaffected by any large scale zone of disturbance bed parallel shear structures are developed along many of the gently dipping coal seams which form a series of simultaneously active detachments representing a process of easy slip thrusting a ne sw striking fold dominated disturbance at gilfach iago is interpreted to overlie a reactivated basement fault a more complex disturbance zone at ffos las combines both e w trending folds and more variably oriented thrusts which together shorten the coal bearing strata by up to 2 km and this is interpreted to be the major variscan frontal thrust ramp in the extreme west of the coalfield the variscan compressional structures within south wales are not consistent with a simple thin skinned thrust system the strain induced by deep seated variscan thrusts was distributed throughout much of the coal bearing sequence by easy slip deformation rather than being localized along a single regional detachment and additional thrusts present around the northern margin of the coalbasin appear to have formed as isolated autochthonous structures the inherent weakness of coal seams across south wales is attributed to the presence of greatly increased fluid pressures which would have been generated both by the maturing coal and by the influx of fluids along deep seated disturbance zones

seismic and acoustic signatures of surficial mass movements at volcanoes abstract surficial mass movements such as debris avalanches rock falls lahars pyroclastic flows and outburst floods are a dominant hazard at many volcanoes worldwide understanding these processes cataloging their spatio temporal occurrence and detecting tracking and characterizing these events would advance the science of volcano monitoring and help mitigate hazards seismic and acoustic methods show promise for achieving these objectives many surficial mass movements generate observable seismic and acoustic signals and many volcanoes are already monitored significant progress has been made toward understanding modeling and extracting quantitative information from seismic and infrasonic signals generated by surficial mass movements however much work remains in this paper we review the state of the art of the topic covering a range of scales and event types from individual rock falls to sector collapses we consider a full variety of volcanic settings from submarine to subaerial shield volcano to stratovolcano finally we discuss future directions toward operational seismo acoustic monitoring of surficial mass movements at volcanoes

coupled fluid dynamics sediment transport modelling of a crater lake break out lahar mt ruapehu new zealand summary lahars and other sudden onset floods are highly dynamic with temporally and spatially evolving sediment loads numerical models of sudden onset flood behaviour particularly those applied to real world events have tended to neglect sediment transport processes this is a serious though perhaps understandable shortcoming given a lack of field measurements on flow bed interactions the extra computational complexity required and the problem of iteratively updating plastic channel boundaries this paper applies a fluid dynamics model with suspended sediment and bedload transport to calculate flow conditions and rapid landscape change due to an initially dilute lahar from mt ruapehu new zealand we take advantage of an unprecedented dataset of net topographic changes determined from pre and post lahar airborne lidar surveys and time series of hydrological measurements to run and validate the model a sensitivity analysis of key controls on water surface elevation and final sediment thickness illustrates how the flow was supply limited in the upper reaches it was capable of transporting a greater volume and calibre of material than that available modelled patterns of net erosion and deposition can replicate those observed r 2 0 79 and are dominantly controlled by channel gradient and topographic

high resolution interpretative geomorphological mapping of river valley environments using airborne lidar data the availability of airborne lidar data provides a new opportunity to overcome some of the problems associated with traditional field based geomorphological mapping such as restrictions on access and constraints of time or cost the combination of airborne lidar data and gis technology facilitates the rapid production of geomorphological maps of floodplain environments however unfiltered lidar data which include vegetation and buildings are currently more suitable for geomorphological mapping than data that have been filtered to remove these features classification of lidar data according to elevation in a gis enables the user to identify and delineate geomorphological features in a manner similar to field mapping but it is necessary to use a range of classification intervals in order to map the various types of feature that occur within a single reach comparison of a lidar derived geomorphological map with an independently produced field geomorphological map showed a high degree of similarity between the results of the two methods although ground truthing is essential in cases where a high degree of accuracy is required ground truthing of a lidar derived geomorphological map showed that around 80 of features mapped using both methods were identified from the lidar data suggesting that the method is suitable for applications such as production of base maps for use in field mapping and selection of sites for detailed investigation copyright 2007 john wiley sons ltd

lignite cleat studies from the first middle polish first lusatian lignite seam in central poland abstract some miocene lignite seams are characterized by the presence of natural discontinuities so called cleats most often they are opening mode fractures consisting of two orthogonal sets face and butt both almost perpendicular to the bedding this paper determines distributions of cleat orientation spacing and aperture from the first group of the middle polish first lusatian lignite seams mpls 1 which has been exploited inter alia in the jo win iib and kazimierz n opencast mines in central poland all observations and measurements were conducted at macroscopic scale the cleats mean orientations are ne sw and nw se dipping at a high angle 75 the first set of fractures refers to the face cleats and the second one to the butt cleats the spacing of face cleats is from 10 0 to 17 2 cm averaging 12 65 cm and the spacing of butt cleats is from 9 3 to 24 3 cm averaging 13 75 cm on the other hand aperture measurements of these cleats range from 0 2 to 1 9 cm averaging 0 68 cm and from 0 1 to 1 5 cm averaging 0 42 cm respectively the obtained results clearly indicate that face cleat orientations nw se are strictly parallel to the elongation of the main tectonic structures in the study area their origin may be explained in at least two ways that is by tectonic folding the maximum principal stress 1 was horizontal or by salt diapirism the maximum principal stress 1 was vertical in both cases the intermediate principal stress 2 was parallel to the face cleat strikes namely nw se although the well developed butt cleats in the context of regional geology provide additional evidence for the creation of an orthogonal system of fractures cleats in the cover of salt structures thus the nw se direction is characteristic of both the extent of the main tectonic units in central poland and the face cleat orientation in mpls 1

fluid migration and coal rank development in foreland basins mathematical modeling of regional fluid flow in the south wales foreland basin shows that heat was transferred from internal to peripheral parts of the basin where very high geothermal gradients and surface heat flow would have developed in the fluid discharge areas temperatures are modeled to have reached 300 c within the coal measures section and would have generated anthracite while more internal parts of the basin were cooled by descending fluid flow and temperatures of only 220 c resulted sufficient to form bituminous coal the modeled thermal regime appears to match the pattern of coal rank observed in the basin the regional flow probably continued for 1 to 2 m y before erosion diminished the topographic gradient driving brine migration in the late paleozoic

current status and geological conditions for the applicability of cbm drilling technologies in china a review abstract coalbed methane cbm drilling technology is critical in achieving efficient cbm development the geological conditions for cbm development in china are complex including special terrain high rank coal areas deep coal seams multiple superposed coal seams and coal measure gas symbiosis areas steeply inclined coal seam areas and tectonic coal seam areas therefore it is critical to apply the optimum drilling technology in each different area this paper first reviews the current cbm drilling technologies and gas production behaviors in china it is found that although vertical wells and cluster well groups are common well types for cbm development in china u v and l shaped horizontal wells and multilateral horizontal wells have been favored for cbm development in recent years the paper then discusses the applicability of different well types to geological conditions and proposes a modification method for well design in various geologic conditions this method uses the coal structure ro in situ stress and ratio of critical desorption pressure to the reservoir pressure as the main inputs

end carboniferous fold thrust structures oxfordshire uk implications for the structural evolution of the late variscan foreland of south central england interpretation of commercial seismic reflection data from the west of banbury south central england has provided information on the late carboniferous structural evolution of the oxfordshire syncline end carboniferous structures are preserved in the footwall of the main basin bounding faults of the permo triassic worcester graben restoration of major pre triassic normal faults has allowed reconstruction of earlier compressional structures in contrast to the wnw ese trend of structures to the south in the variscan foreland fold thrust belt major faults and folds in oxfordshire are approximately n s trending the structures seen to deform westphalian d stephanian aged sequences on the seismic profiles are a combination of steep 30 40 dip fault bounded uplifts and less dominant thin skinned tectonics apparently showing transport to the east in the south some thin skinned structures are present and in the north cover sequences are uplifted in a narrow zone of deformation on reactivated basement faults the amount of shortening also changes along strike from c 1600 m in the south to c 950 m in the north reactivation of major basement faults with differential basement shortening accounts for the main structures localized detachment in the young and weak sediments close to the palaeo land surface explains the thin skinned structures seen on some of the seismic lines these end carboniferous structures in oxfordshire and structures in the malvern abberley hills represent the structural limits of a large n s striking intra stephanian uplift in the late variscan foreland it is suggested that the structures formed during a discrete phase of intra stephanian e w directed regional shortening prior to the final phase of movement in the variscan belt

defining conditions for bulking and debulking in lahars through measurements at semeru volcano east java we define the conditions under which bulking entrainment of sediment and pore water and debulking dilution and sedimentation occur in rain triggered volcanic floods lahars two observation sites were installed 510 m apart along the curah lengkong river 11 5 km southeast of semeru s summit this 30 m wide box valley with a gravel and lava base represents a real world flume analogy pore pressure sensors provided stage measurements a broad band seismograph gave insight into sediment content and frictional collisional behavior video cameras were used to measure surface velocities and direct bucket samples were taken eight rainfall induced lahars were recorded lasting 1 3 h with heights of 0 5 2 m peak velocities of 3 7 m s and discharges of 25 250 m3 s flows ranged from typical 40 wt sediment to coarse and dense hyperconcentrated flows 50 60 wt sediment multiple distinct flow packets occurred within the complex lahars and were used to determine internal changes between sites from the multiparameter data set at each site volumetric bulking and wave shortening due to portions of the lahar accelerating toward the flow front are identified initial debulking of lahars between sites may reflect drainage into the dry substrate estimates of discharge and volume at each site lead to the quantification of bulking and debulking by these actively flowing lahars along the channel reach from this we observe that bulking can be localized to certain parts of lahars resulting in intraevent increases in peak discharge that are greater than what would occur if bulking was evenly distributed throughout the flow such data are essential for the development of numerical descriptions and hazard models for mass flows

geochemical effects of petroleum migration and expulsion from toarcian source rocks in the hils syncline area nw germany for mature oil prone source rocks of toarcian age in the hils syncline area nw germany the geochemical effects of primary migration of petroleum are shown expulsion has occurred at high efficiencies primarily via a network of macro and micro fractures the effects of this fracture controlled expulsion with respect to gross and molecular composition of c15 soluble organic matter are documented samples from fractured intervals have expelled total c15 soluble organic matter more efficiently than adjacent unfractured intervals a systematic comparison of samples taken at cm intervals away from macro fractures reveals compositional gradients which are interpreted to reflect preferential depletion of saturated and aromatic hydrocarbons from the source rock shale into the fractures extracts of shale samples directly at fracture walls are enriched in nso compounds and highly polar asphaltene like fractions the composition of residual petroleum fluids extracted from the fracture fill materials is variable in some cases there is a close match with that of the shale at some distance away from the fractures in other cases there is geochemical evidence to suggest that petroleum fluids were chemically altered during lateral flow along the fractures based on available geological and geochemical evidence a conceptual model is proposed to explain fracture development and fluid flow processes rapid heating by a nearby intrusive body at shallow depths when the toarcian sediments still contained about 15 20 pore water has played an important role overpressuring of aqueous pore fluids with abundant dissolved carbonate caused intense fracturing of the rich intervals in the mature toarcian sections finally the closely interdependent relationships between petroleum generation and petroleum migration processes are documented especially the evolution of these relationships with maturity progress from immature 0 48 rm to mature 0 68 and 0 88 rm and overmature 1 45 rm stages is shown for example in the maturity interval from 0 68 to 0 88 rm most of the measured shale compaction and porosity decrease is achieved by expulsion of petroleum for some samples there is an inverse relationship between kerogen quality and extractable hydrocarbon yields suggesting that expulsion efficiencies were higher from the better quality intervals because the petroleum achieved higher saturations and hence higher relative permeabilities

mechanisms of coal metamorphism case studies from paleozoic coalfields controls on coal metamorphism can be complex in this paper we examine four paleozoic coalfields the western kentucky portion of the illinois basin the pennsylvania anthracite fields the south wales coalfield and the bowen basin an increase in temperature with depth of burial is certainly a factor in coal metamorphism in many coalfields however including the coalfields reviewed here it has become apparent that such a simple mechanism does not explain the coal rank patterns observed the flow of hydrothermal fluids through the coals has been proposed as a cause of coal metamorphism evidence includes inverted rank gradients elevated cfl as an indicator of brine fluids isotopic evidence for hydrothermal fluids and vein and cleat mineral assemblages in any case multiple hypotheses must often be evaluated in the examination of any coalfield since the simple paradigm of coal rank increases with a simple increase in temperature with increasing depth does not fit the evidence observed in many cases

sedimentological processes in lahars insights from optically stimulated luminescence analysis abstract a lahar is a sediment laden flow capable of major destructive impacts on infrastructure and human life how lahars transport sediment is thus a key issue for understanding lahar sedimentology and behavior especially in terms of the lahar s hydraulic and rheological properties which can be substantially altered as the lahar gains or loses material during its travel in this research we analyze lahar entrainment processes by evaluating luminescence signals total photon counts from lahar sediments using blue luminescence signals blsl a portable osl reader that analyzes several grams of polymineral and polygrain size samples was applied we use data from three lahars in the tenenepanco and huiloac gorges on popocatepetl volcano mexico to elucidate the ways in which lahars may gain lose and transport sediment during flow sediment samples for luminescence analysis were taken through the full thickness of the lahar deposits at eight different sites for two lahars 1997 and 2001 and at one site for a lahar that occurred 500 yrs ago mean luminescence values obtained for the 1997 lahar help to evaluate the relationship between the lahar entrainment processes and the drainage at the different sites for the 2001 lahar this relationship was also established taking into account the channel slope the main conclusion is that luminescence signals total photon counts can be used to detect entrained material in the flow because the bulked materials modify the final osl signals the application of this type of luminescence analysis thus has the potential to provide a better understanding of sediment entrainment in these sediment laden flows

sediment entrainment by debris flows in situ measurements from the headwaters of a steep catchment 1 debris flows can dramatically increase their volume and hence their destructive potential by entraining sediment yet quantitative constraints on rates and mechanics of sediment entrainment by debris flows are limited using an in situ sensor network in the headwaters of a natural catchment we measured flow and bed properties during six erosive debris flow events despite similar flow properties and thicknesses of bed sediment entrained across all events time averaged entrainment rates were significantly faster for bed sediment that was saturated prior to flow arrival compared with rates for sediment that was dry bed sediment was entrained from the sediment surface downward in a progressive fashion and occurred during passage of dense granular fronts as well as water rich inter surge flow en massefailure of bed sediment along the sediment bedrock interface was never observed large magnitude high frequency fluctuations in total normal basal stress were dissipated within the upper 5 cm of bed sediment within this near surface layer concomitant fluctuations in coulomb frictional resistance are expected irrespective of the influence of pore fluid pressure or fluctuations in shear stress if the near surface sediment was wet as it was overridden by a flow additional large magnitude high frequency pore pressure fluctuations were measured in the near surface bed sediment these pore pressure fluctuations propagated to depth at subsonic rates and in a diffusive manner the depth to which large excess pore pressures propagated was typically less than 10 cm but scaled as d fi 0 5 in which d is the hydraulic diffusivity and fiis the frequency of a particular pore pressure fluctuation shallow penetration depths of granular normal stress fluctuations and excess pore pressures demonstrate that only near surface bed sediment experiences the full dynamic range of effective stress fluctuations and as a result can be more easily entrained than deeper sediment these data provide robust tests for mechanical models of entrainment and demonstrate that a debris flow over wet bed sediment will be larger than the same flow over dry bed sediment

a mountain front model for the variscan deformation of the south wales coalfield access to the considerable geological database of british coal together with seismic evidence of subsurface relationships has enabled the development of a structural model for the south wales coalfield detailed site investigations are used as key examples the simple broad synclinal nature of the coalfield masks a more complex structural system thrusting of variscan age is largely confined to the lower and middle coal measures and throughout the central and northern coalfield is dominantly a forethrust system however along the south crop a major backthrust system is developed which in places penetrates the upper coal measures the south crop shows features analogous with a mountain front and is interpreted as a triangle zone in which pre existing basement faults have facilitated uplift the lack of thrusting within the upper coal measures in contrast to the underlying lower and middle coal measures suggests they have acted as a passive roof to the thrust system geographical variation in the intensity of the deformation can be related to the proximity of and buttressing against the caledonian massif although broadly analogous with current models of foreland basin development and deformation the south wales coalfield demonstrates the importance of pre existing massifs and lineaments in determining the precise evolution of an area

paleo stress estimates on ancient seismogenic faults based on frictional heating of coal 1 faulted coals from eastern kentucky and montana usa and the south wales coalfield uk show fault related vitrinite reflectance anomalies interpreted as due to frictional heating during seismic slip the vitrinite reflectance anomalies are converted to temperature using kinetic based software easy r for post seismic cooling rates shear stresses are calculated using lachenbruch s 1986 piezometer which depends only on the area under the thermal anomaly and fault displacement for maximum displacements of 1 3 meters the minimum shear stresses are 13 64 mpa and overlap with seismological estimates of stress drops during modern earthquakes the calculated local mean normal stress is 100 mpa resulting in coefficients of friction of 0 1 0 6 thrust and 0 2 0 4 normal faults which are lower than laboratory based values

channel floodplain connectivity during an extreme flood event implications for sediment erosion deposition and delivery the term connectivity has emerged as a powerful concept in hydrology and geomorphology and is emerging as an innovative component of catchment erosion modeling studies however considerable confusion remains regarding its definition and quantification especially as it relates to fluvial systems this confusion is exacerbated by a lack of detailed case studies and by the tendency to treat water and sediment separately extreme flood events provide a useful framework to assess variability in connectivity particularly the connection between channels and floodplains the catastrophic flood of january 2011 in the lockyer valley southeast queensland australia provides an opportunity to examine this dimension in some detail and to determine how these dynamics operate under high flow regimes high resolution aerial photographs and multi temporal lidar digital elevation models dems coupled with hydrological modeling are used to assess both the nature of hydrologic and sedimentological connectivity and their dominant controls longitudinal variations in flood inundation extent led to the identification of nine reaches which displayed varying channel floodplain connectivity the major control on connectivity was significant non linear changes in channel capacity due to the presence of notable macrochannels which contained a 3000 average recurrence interval ari event at mid catchment locations the spatial pattern of hydrological connectivity was not straight forward in spite of bankfull discharges for selected reaches exceeding 5600m 3 s 1 data indicate that the main channel boundary was the dominant source of sediment while the floodplains where inundated were the dominant sinks spatial variability in channel floodplain hydrological connectivity leads to dis connectivity in the downstream transfer of sediments between reaches and affected sediment storage on adjacent floodplains consideration of such variability for even the most extreme flood events highlights the need to carefully consider non linear changes in key variables such as channel capacity and flood conveyance in the development of a quantitative connectivity index copyright c 2013 john wiley sons ltd

thrusting in a folded regime fold accommodation faults in the ruhr basin germany abstract the late carboniferous ruhr basin in germany has been described as an authochtonous foreland basin of the variscan orogen the structure of the basin is fold dominated with fold accommodation faults as secondary elements vast and excellently documented 3d mining exposures provide extensive data on the geometry of thrusts and the relationship between thrusting and folding stratigraphic throw is the determining factor in the geometry of thrusts and displacement and shortening are functions of throw material behaviour and bedding dip built up on a basic geometric model a complex system of different fault types can be described linked regularly to each other and developed during the folding process

the association between tectonic deformation inorganic composition and coal rank in the bituminous coals from the south wales coalfield united kingdom analysis of vertical distribution of coal rank in three collieries and one opencast mine in the se of the south wales coalfield has revealed deviations from hilt s law in both proximate analyses and in vitrinite reflectance the variations in rank parameters studied are closely correlated with variations in the intensity of tectonic deformation measured using a numerical deformation index ndi three seams in the sequence were also analysed for major and trace element geochemistry and rock eval pyrolysis variations in these parameters are related to thrust inclusion of floor and or roof mudrocks into the seams a detailed conceptual model of a major thrust and associated in seam thrust detachments and lag faults is developed to explain the vertical rank profile by post coalification faulting it is concluded that although the model can explain the vertical pattern of rank the complexity of the required faults render the model improbable the alternative mechanisms for enhancement of the rank parameters associated with tectonic deformation including shear stress control frictional heating and localised fluid flow are discussed and are thought more likely to be responsible for the deviations from hilt s law in the vertical rank profile rank suppression shown by three seams two of which are overlain by marine bands is thought to be related to biochemical activity in the peat environment resulting from the influx of saline waters

striated conical structures and related fractures in bituminous coal of the southern canadian rocky mountains abstract striated structures many of which are conical in form are common mesoscopic features in bituminous and semi anthracite coals of the southern canadian rocky mountains the structures are planar conical to pyramidal in outline and are characterized by striae which radiate from a common apex and bifurcate or horsetail to form secondary structures on the master surface they are up to 20 cm in length 4 cm in width and have apical angles varying from 10 to 50 the striated structures occur at numerous localities in both highly sheared and relatively unsheared coal seams the conical striated structures closely resemble some shatter cones developed in fine grained rocks whereas the planar striated structures are somewhat similar to chevron structured hackle marked joints the pyramidal structures are apparently unique to coal all three types of structures are considered to be the result of brittle shear fracture based on their occurrence orientation and morphology the apparently restricted occurrence of the structures to coal is likely a function of the homogeneity and low tensile and compressive strength of bituminous and semi anthracite coals possibly augmented by high inter and or intra particle gas pressure resulting from devolatization of the coal during progressive coalification

changes in optical properties of liptinite macerals from early mature to post mature stage in posidonia shale lower toarcian nw germany abstract detailed organo petrological analysis was carried out on core samples of posidonia shale lower toarcian from two wells which are located in northwestern germany lower saxony basin organic matter in one well is early mature vrr 0 5 whereas organic matter in the other is post mature vrr 3 5 results of organo petrological analyses demonstrate that telalginite tasmanales alginite in early mature oil shales appears brown to dark brown in reflected white light whereas in fluorescence mode it shows a yellow color of high intensity in contrast in post mature oil shales relics of former telalginite named postmature telalginite for the purposes of the maceral analysis occur in three forms of replacement of former telalginite bodies whose shape and size are preserved one form consists of a chain of carbonate crystals or of a completely recrystallized calcareous mass both are associated with homogeneous and heterogeneous migrabitumen the second form is completely composed of epigenetic pyrite the third form of postmature telalginite is rare and consists of impsonite in mature posidonia shale lamalginite is relative frequent and has been encountered in three forms discrete 10 m and layered in post mature posidonia shale all these forms are no longer recognizable part of the micrinite dispersed in the mineral groundmass may have been derived from lamalginite in oil shales of early mature stage bituminite i is characterized by a very low reflectance and a brownish fluorescence color it often includes yellow fluorescent liptodetrinite and has indistinct lense shape on the contrary in post mature oil shales on the basis of morphology it appears as light gray lenses which consist of massive micrinite bituminite ii in early mature oil shales occurs as thick elongated homogeneous lenses and streaks associated with tiny carbonate crystals and with yellow brownish fluorescence often with greenish fluorescent oil expulsions in post mature oil shales postmature bituminite ii consists of a network of micrinite between tiny carbonate crystals apart from these common bituminites minor contents of other bituminites have been recorded sporinite in early mature oil shales has a very low reflectance and an orange brown fluorescence of moderate intensity in post mature oil shales sporinite shows reddish orange internal reflections and is filled with pyrite crystals or with weak fluorescing minerals which emphasize the sporinite form this study demonstrates that the use of the terms postmature telalginite postmature bituminite and postmature sporinite in the macerals analysis of post mature oil shales is highly profitable particularly in understanding the transformation processes which are the result of the formation of secondary products secondary macerals and epigenetic minerals in the primary liptinite macerals

changes in whangaehu river lahar characteristics during the 1995 eruption sequence ruapehu volcano new zealand abstract during the 1995 ruapehu eruptive sequence multiple lahars occurred in the whangaehu river which drains ruapehu s crater lake during the earlier phreatic and phreatomagmatic eruptions lahars were generated by expulsion of waters from the lake but once the lake had emptied lahars were formed by remobilisation of seasonal snowpack laden with saturated freshly erupted tephra four types of lahars occurred during the eruptive sequence 1 initial snow slurry lahars composed of granular snow and ice incorporated by eruptively expelled crater lake waters which left behind frozen deposits with 2 5 20 clastic sediment 2 large dilute lahars generated as the volumes of ejected lake water increased and removed much of the readily available snow at least one third of the pre eruption crater lake volume was expelled during one day producing the largest lahars of the series these lahars were hyperconcentrated flows for up to 84 km from source leaving extensive deposits along the channel margins 3 concentrated lahars smaller volume lahars generated as the frequency of eruptions and volumes of expelled water declined these lahars were able to maintain high sediment concentrations measured at 46 52 by volume suspended sediment at 42 km from source their high sediment concentrations were maintained by erosion and incorporation of sand from the deposits of earlier flows which were lining the channel margins 4 remobilised tephra lahars generated following the two largest tephra eruptions of the sequence seasonal snowpack was covered by water saturated tephra warmer spring temperatures and heavy rainfall events caused collapse and remobilisation of snow and tephra producing several lahars in catchments draining eastern ruapehu

energy growth in laharic mass flows lahars debris flows and sediment rich floods are frequent and deadly hazards at all mountain forming volcanoes their hazard potential is traditionally assessed through mass conserving closed system models where peak conversion rates of potential energy to mechanical energy and hence maximum destruction potential are predicted to occur on the steepest volcano flanks this belies evidence of extremely high energy and deadly catastrophes caused by such flows at large distances from volcanoes here we use the first high resolution record of a moving lahar to develop a new model of the temporally and spatially variable mass flow structure we show that bulk flow energy can grow dramatically in such systems over tens to hundreds of kilometers via momentum transfers from the lahar into water and particles along its path we also demonstrate that dynamic transformations of such flows and their ultimate runout are primarily controlled by the mass flow front

shale oil occurring between salt intervals in the dongpu depression bohai bay basin china abstract the saline mudstone sequence of the paleogene shahejie formation in the dongpu depression of bohai bay basin is a major source rock for conventional hydrocarbons however shale oil having a density of 0 9 g cm 3 and a viscosity of 21 mpa s has also been discovered and is being produced from these mudstones to better understand the occurrence of such shale oil geochemical petrological and mineralogical investigations were carried out on a suite of saline mudstone samples by using rock eval x ray diffraction and sem the shahejie formation samples analyzed in the current study are characterized by type ii kerogen with lesser amounts of types i and iii such that petroleum generation ranges from fair to excellent in general terms with the exception of es1 uppermost member which is immature to marginally mature for oil generation the sequence studied ranges from mature for oil generation to mature for wet gas generation on the basis of vitrinite reflectance data the most prospective depths for shale oil condensate generation are between 2300 and 4000 m depth in area studied the saline mudstones comprise mainly clay minerals followed by carbonates quartz and feldspar based solely on the brittle mineral index the amounts of carbonate and quartz in many of the samples lead to a similar or greater suitability for hydraulic fracturing than for many haynesville woodford and upper bakken shales sem studies show that abundant micro fractures commonly occur in the mudstones and these include tectonic fractures bedding plane fractures shrinkage fractures and over pressured fractures for the es3 m middle third member unit shale oil prospectivity is likely to be enhanced around the towns of wl wenliu lt liutun and hbz hubuzhai due to the increased frequency of tectonic fractures which would contribute to oil storage and flow mineral interparticle mineral intraparticle and organic matter pores are well developed in the rocks studied mineral dissolution has created secondary pores in some areas such that reservoir capacity is increased the increased concentration of organic acids between 2800 and 3500 m is likely to lead to enhanced shale oil prospectivity the micro fractures and dissolution pores are probably the main reservoirs for shale oil accumulation the association of these features with saline facies potentially offers an exploration tool for further shale oil occurrences in the studied area as well as in other areas containing similar lithologies

application of seismic curvature attributes in the delineation of coal texture and deformation in zhengzhuang field southern qinshui basin coal texture refers to the in situ particle size morphological characteristics and structural components of coal beds and it determines the permeability and producibility of a coalbed methane cbm reservoir coal texture is commonly classified into undeformed coal with primary coal texture and deformed coal with increasing degree of deformation including cataclastic coal granulated coal and mylonitized coal geophysical logging has recently been proven effective for detecting coal texture in boreholes but it is inefficient for establishing a regional distribution where there have been only limited amounts of drilling in contrast seismic attributes have high lateral extent and an advantage in terms of characterizing fine structures even minor faults with throws of 2 3 m and other strata deformations by comparing seismic curvature data to the results of 221 core samples from the zhengzhuang field in the southern qinshui basin we provide a seismic curvature attribute based coal texture evaluation method evaluation of the results shows that the coal texture types of the no 3 coal seam include undeformed coal cataclastic coal and some granulated coal the undeformed coal is mainly located in the western and northwestern parts of the study area the cataclastic and granulated coals are mainly distributed in the southern and eastern parts of the study areas the permeability of no 3 coal seam is weakly correlated with undeformed coal and it has a high negative correlation with deformed coal permeability has a strong negative correlation with the maximum curvature attribute of the no 3 coal seam it is suggested that the in situ stress distribution combined with the curvature controlled the local development of the coal texture types and thus resulted in regional differences in permeability finally the distribution characteristics of coal textures of no 3 coal seam in the study area are divided into four types in which the undeformed cataclastic coal dominated area located in the midwestern part of the study area is the most favorable area for cbm production

the use of multi temporal lidar to assess basin scale erosion and deposition following the catastrophic january 2011 lockyer flood se queensland australia advances in remote sensing and digital terrain processing now allow for a sophisticated analysis of spatial and temporal changes in erosion and deposition digital elevation models dems can now be constructed and differenced to produce dems of difference dod which are used to assess net landscape change for morphological budgeting to date this has been most effectively achieved in gravel bed rivers over relatively small spatial scales if the full potential of the technology is to be realised additional studies are required at larger scales and across a wider range of geomorphic features this study presents an assessment of the basin scale spatial patterns of erosion deposition and net morphological change that resulted from a catastrophic flood event in the lockyer creek catchment of se queensland seq in january 2011 multitemporal light detection and ranging lidar dems were used to construct a dod that was then combined with a one dimensional flow hydraulic model hec ras to delineate five major geomorphic landforms including inner channel area within channel benches macrochannel banks and floodplain the lidar uncertainties were quantified and applied together with a probabilistic representation of uncertainty thresholded at a conservative 95 confidence interval the elevation change distribution ecd for the 100 km2 study area indicates a magnitude of elevation change spanning almost 10 m but the mean elevation change of 0 04 m confirms that a large part of the landscape was characterised by relatively low magnitude changes over a large spatial area mean elevation changes varied by geomorphic feature and only two the within channel benches and macrochannel banks were net erosional with an estimated combined loss of 1 815 149 m3 of sediment the floodplain was the zone of major net deposition but mean elevation changes approached the defined critical limit of uncertainty areal and volumetric ecds for this extreme event provide a representative expression of the balance between erosion and deposition and importantly sediment redistribution which is extremely difficult to quantify using more traditional channel planform or cross sectional surveys the ability of lidar to make a rapid and accurate assessment of key geomorphic processes over large spatial scales contributes to our understanding of key processes and as demonstrated here to the assessment of major geomorphological hazards such as extreme flood events

modeling the october 2005 lahars at panabaj guatemala an extreme rainfall event in october of 2005 triggered two deadly lahars on the flanks of toliman volcano guatemala that caused many fatalities in the village of panabaj we mapped the deposits of these lahars then developed computer simulations of the lahars using the geologic data and compared simulated area inundated by the flows to mapped area inundated computer simulation of the two lahars was dramatically improved after calibration with geological data specifically detailed field measurements of flow inundation area flow thickness flow direction and velocity estimates collected after lahar emplacement were used to calibrate the rheological input parameters for the models including deposit volume yield strength sediment and water concentrations and manning roughness coefficients simulations of the two lahars with volumes of 240 200 55 400 and 126 000 29 000 m3 using the flo 2d computer program produced models of lahar runout within 3 of measured runouts and produced reasonable estimates of flow thickness and velocity along the lengths of the simulated flows we compare areas inundated using the jaccard fit model sensitivity and model precision metrics all related to bayes theorem these metrics show that false negatives areas inundated by the observed lahar where not simulated and false positives areas not inundated by the observed lahar where inundation was simulated are reduced using a model calibrated by rheology the metrics offer a procedure for tuning model performance that will enhance model accuracy and make numerical models a more robust tool for natural hazard reduction

identification of coal structures using geophysical logging data in qinshui basin china investigation by kernel fisher discriminant analysis abstract coal structure is closely related to the porosity and permeability of coal reservoirs which not only affects the enrichment of coalbed methane cbm but also influences the hydraulic fracturing and efficient development of cbm the accurate identification of the coal structure would be a critical issue in cbm exploration and development and is always a challenge compared with traditional methods for identifying coal structure base on borehole cores or mining seam observation geophysical logging has become the most economic and efficient technique several linear correlations have been established to describe the relationships between the coal structures and well logs however those correlations cannot accurately reflect nonlinear relations between them therefore a reliable and efficient method to identify coal structure is needed as a powerful nonlinear classifier the kernel fisher discriminant analysis kfd method has been widely used due to its strong generalization ability in this paper a new quantitative coal structure identification model was developed based on the kfd method by using geophysical logging data the model was trained tested and optimized using 178 logging data sets from 15 cbm wells in qinshui basin china the approach accounted for all the available well logging attributes and the training data sizes and kernel parameters were analyzed to get the most appropriate model in practice in addition the built model was validated individually by employing logging data of a new cbm well the results indicate that the kfd based identification model has high prediction accuracy which can be used as a reliable method for coal structure identification the kfd method exhibits strong capability during the modeling and generalization in the determination of nonlinear relationships which provides an efficient way for the coal structure prediction in basic research of coal reservoirs

lahar hazard assessment using titan2d for an alluvial fan with rapidly changing geomorphology whangaehu river mt ruapehu abstract rapid changes in small areas at the apex of alluvial fans may have devastating consequences by directing downstream flood or lahar impacts into catchments of widely varying population or infrastructure vulnerability during a series of lahars in 1995 at mt ruapehu new zealand aggradation of the whangaehu fan apex draining the eastern edifice caused the onset of avulsion of flows northward into the highly vulnerable tongariro catchment an earth training dike or bund was constructed to protect this catchment by retaining flows on the southern side and the normal lahar outlet path to the south surveys in 2001 late 2005 and following a major lahar in march 2007 now show net degradation of a channel in the whangaehu fan apex bordered by the bund this indicates a net increase in the channel capacity at this site and shows that the bund remains at its effective design capacity past hydrological modelling used for the bund design provided a large range of discharge estimates but lacked precise constraints on the size and nature of lahars from eruption and lake breakout events new modelling has been carried out using titan2d to examine the impacts of a 6 106 m3 volume granular flow down this catchment this simulates either an eruption or a lake breakout induced lahar with a historically typical volumetric bulking factor of 4 these simulations predict minimum discharges between 1800 and 2100 m3 s at the bund site by comparison the largest 1995 flow at this site was estimated at around 1200 m3 s further any single modelled flow from the normal outlet channel of crater lake could not be induced to overtop the bund because discharge appears to be limited by the narrow upper reaches of the whangaehu gorge theoretical discharge levels required to overtop the bund are estimated to be 6800 m3 s assuming no aggradation of the channel by the decelerating flow maximum potential discharge at the bund site is additionally modified by potential bifurcation of lahars above a certain size threshold at a point 2 5 km upstream of the bund a major side channel the chute effectively diverts part of the flows away to the southern side of the whangaehu fan this potential for splitting of the flow appears to have increased since 1995 from aggradation of lahar deposits and reworked sediment in the area immediately upstream of the divide despite remaining at design capacity for lahar events in the whangaehu erosion of new channels following the 2007 lahar renders the bund vulnerable to undercutting

rapid reservoir erosion hyperconcentrated flow and downstream deposition triggered by breaching of 38 m tall condit dam white salmon river washington condit dam on the white salmon river washington a 38 m high dam impounding a large volume 1 8 million m3 of fine grained sediment 60 sand 35 silt and clay and 5 gravel was rapidly breached in october 2011 this unique dam decommissioning produced dramatic upstream and downstream geomorphic responses in the hours and weeks following breaching blasting a 5 m wide hole into the base of the dam resulted in rapid reservoir drawdown abruptly releasing 1 6 million m3 of reservoir water exposing reservoir sediment to erosion and triggering mass failures of the thickly accumulated reservoir sediment within 90 min of breaching the reservoir s water and 10 of its sediment had evacuated at a gauging station 2 3 km downstream flow increased briefly by 400 m3 s 1 during passage of the initial pulse of released reservoir water followed by a highly concentrated flow phase up to 32 sediment by volume as landslide generated slurries from the reservoir moved downstream this hyperconcentrated flow analogous to those following volcanic eruptions or large landslides draped the downstream river with predominantly fine sand during the ensuing weeks suspended sediment concentration declined and sand and gravel bed load derived from continued reservoir erosion aggraded the channel by 1 m at the gauging station after which the river incised back to near its initial elevation at this site within 15 weeks after breaching over 1 million m3 of suspended load is estimated to have passed the gauging station consistent with estimates that 60 of the reservoir s sediment had eroded this dam removal highlights the influence of interactions among reservoir erosion processes sediment composition and style of decommissioning on rate of reservoir erosion and consequent downstream behavior of released sediment

lahars of ruapehu volcano new zealand risk mitigation a dam break lahar resulting from the last eruption of ruapehu is expected when crater lake reaches a critical high level probably within the next 1 5 summers a high level of public consultation political decision making and ongoing scientific input has occurred to address the risks decisions about managing lahar risk have taken into account the fact that lahars are common on the active ruapehu volcano 2797 m and in valleys draining the mountain and that most lahars are generated by eruptions about half of which have no useful precursors lahars threaten new zealand s largest ski area and nationally important infrastructure public safety has been the main consideration but the need for long term risk mitigation and reducing impacts on tongariro national park world heritage area have also been important lahar mitigation on ruapehu now includes six lahar warning systems each with active response plans and some infrastructure isolated from or hardened against lahars

dynamic interactions between lahars and stream flow a case study from ruapehu volcano new zealand three lahars were sampled in the whan gaehu river on the eastern flank of ruapehu volcano new zealand at 23 5 and 42 km from the source as they were flowing on september 27 and 29 and october 6 1995 the lahars were generated by water explosively ejected from the highly mineralized crater lake we used the chemical contrast between the lahars and resident stream water in their paths to describe a four phase model of a noncohesive lahar wave in a river channel 1 ambient stream water pushed ahead of the lahar in a process of miscible displacement due to hydrodynamic dispersion 2 a zone of mixing between the stream water and the lahar that increases in length with distance from source 3 a remnant of the original lahar least diluted by stream water that decreases in length and dilutes downstream 4 the tail of the lahar surge peak discharge occurs at the end of phase 1 as water is pushed ahead of the lahar peak sediment concentration occurs at the end of phase 2 where debris entrainment by the flow is at its greatest i e in front of the lahar proper deposits record only phases 2 and 3 of the lahar wave phase 1 flow left only a tide line of organic debris and phase 4 deposits were rapidly eroded by later streamflow downstream dilution by stream water eventually caused transformation of phases 2 and 3 of the lahars from debris flow to hyperconcentrated streamflow and then to normal streamflow as the flows became progressively finer grained and more turbulent

evaluation of coal texture distributions in the southern qinshui basin north china investigation by a multiple geophysical logging method abstract coal texture is indicative of coal mechanical strength which is important not only for evaluating coalbed methane cbm reservoir permeability but also for evaluating the possibility of coal and gas outbursts in underground coal mining this paper begins with a foundation of a geophysical logging based coal texture evaluation method that compares the digital logging data with the results from 108 coring samples then the method was applied to the analyses of coal textures in 39 cbm wells the results of which are discussed in terms of the vertical distribution of coal textures in the study area finally a ternary diagram based on thickness proportions of coal textures was used to identify reservoir compartments in the zhengzhuang field of the southern qinshui basin the results show that undeformed coals are easily distinguished from cataclastic and granulated coals because of the high den and gr of undeformed coals meanwhile cataclastic coal has lower response values of ac and lld than granulated coal which can be used in identifying cataclastic from granulated coal a multiple geophysical logging method combining the log data of den gr ac and lld was provided for predication of the coal textures in the zhengzhuang field the predicated results show that the coal seam can be vertically divided into three to eight sub layers with a typical interbedded pattern of undeformed and cataclastic coals on the upper and lower parts and granulated coal in the middle at a relatively large thickness the study area is divided into four major regions and 11 sub regions based on the classification of coal texture types the undeformed coal dominated region is located in the southwestern part of the study area indicating a low permeability in the coal reservoir the granulated coal dominated region is mainly in the northern and eastern parts of the study area and has resulted from deep burial and multi period structural activities the cataclastic coal dominated region is in the middle of the study area the coal reservoir in this region is possibly the most favorable for cbm production

effects of structural deformation on formation of coalbed methane reservoirs in huaibei coalfield china tectonically deformed coal is defined as coal formed by superimposed reformations from tectonic stress the huaibei coalfield is typically composed of various tectonically deformed coals containing rich coalbed methane resources however the occurrence of coal seam in this area is complicated largely by the structural deformation which has not yet been evaluated systematically for exploration and exploitation of coalbed methane in this study tectonism in huaibei coalfield is discussed by combining systematic analyses on the occurrence of coal seams and the formation of coalbed methane reservoirs the study shows that with structural deformation in the study area the coal seams in huaibei coalfield are distributed in north south tectonic blocks and east west tectonic zones north tectonic block of huaibei coalfield is not favourable for exploitation of coalbed methane because of low gas content or disadvantageous structural conditions within the south tectonic block the east suzhou syncline contains high gas content but coal permeability is very low this area is generally not suitable for exploitation of coalbed methane and is a dangerous mining area due to gas outburst because of the widely developed mylonitic coals south suzhou and nanping synclines in the middle part of the south tectonic block are exposed to relatively weak structural deformations these synclines contain coals with high gas content and moderate permeability which are beneficial for exploration and exploitation of coalbed methane linhuan mining area in the south tectonic block is generally not suitable for exploitation of coalbed methane mainly because of well developed normal faults and interlayer slip structure and presence of mylonitic coal resulting in low gas content and poor structural conditions for mining coalbed methane in contrast guoyang mining area in the west part of the south tectonic block where tectonically deformed coal was generally underdeveloped is a potential area for exploration and exploitation of coalbed methane because of moderate gas content and possibly higher permeability of its coal