evidence for multiple sources for inorganic components in the tucheng coal deposit western guizhou china and the lack of critical elements abstract terrigenous materials from sediment source regions are important controls on the types and concentrations of inorganic components in coal the kangdian upland dominated by the emeishan basalts is the dominant terrigenous supplier for most of the late permian coals as well as for their associated host rocks roof and floor strata in southwestern china the high volatile bituminous coals nos 3 and 6 coals are the two major minable coal seams in the tucheng coal deposit in southwestern china unlike most late permian coals in this region that are characterized by elevated concentrations of the element assemblage sc v cr co ni cu zn se these two coals are not enriched in this assemblage although se is slightly concentrated the mineralogical e g relatively abundant quartz and mixed layer illite smectite and elemental distribution patterns e g spider diagrams of rare earth elements discrimination diagrams of al2o3 tio2 and zr tio2 nb y and elemental assemblages indicate that the inorganic components in the two coal seams were mainly derived from unidentified volcanic arc and or distal orogens while the clastic components in the roof and floor strata of the two coal seams were mainly supplied by the high ti emeishan basalts the two partings in the two coal seams identified as tonsteins were probably derived from the final rejuvenated activity of the emeishan plume critical elements in the two coals and associated non coal horizons partings roof and floor strata are economically unpromising indicating that prospecting for late permian coal hosted critical metal ore deposits in the vicinity of the emeishan plume in southwestern china should not be focused on coals with inorganic components derived mostly from distal volcanic arcs and orogens and high ti emeishan basalts and a minor contribution of volcanic ashes resulting from the final rejuvenated activity of the emeishan plume

structural analysis and interpretation of the surface deformations of the el asnam earthquake of october 10 1980 the el asnam earthquake of october 10 1980 represents the major seismotectonic event of these last decades in the west mediterranean area it has induced a large amount of surface breaks this earthquake reveals the importance of compressional phenomena that characterize nowadays the tectonics of north africa the tectonic analysis of surface rupture shows the complexity of the deformation mechanism the principal mechanism consists of the activation of a nw se trending thrust fault accompanied with a left lateral motion and with an intense deformation of the northwestern overthrusting block an accurate description of these deformations shows that for a large part the breaks geometry depends closely on the substratum structure finally the analysis of the dislocations on irrigation ducts just above the fault traces allowed a quantitative study of the deformation

geological interpretation of gas content trends walloon subgroup eastern surat basin queensland australia abstract the middle jurassic walloon subgroup is a prolific low rank coal seam gas csg resource in the surat basin australia this study applied a regionally consistent stratigraphic framework model to open file gas desorption and coal property data from 69 cored csg wells to assess spatial trends in gas content and test the influence of large scale geological heterogeneity on present day gas distribution continued successful exploration and production and possible future microbial regeneration of the walloon csg resource require an improved understanding of the controls on gas content distribution across the core region of production in the eastern surat basin the walloon subgroup can be subdivided into upper juandah and lower taroom coal measures separated by a relatively coal barren and sandstone dominated unit tangalooma sandstone within these units lateral variation in coal character is high precluding a regionally agreed coal group or seam correlation while the total dataset shows a general increase in gas content dry ash free d a f with increasing depth as a function of hydrostatic pressure there is considerable scatter in the distribution within individual wells gas content follows one of three trends gas content either 1 increases 2 increases then decreases or 3 decreases with depth trend 2 parabolic wells predominate with the gas content maxima coinciding with the tangalooma sandstone regardless of depth as such gas content layering follows rather than cross cuts the stratigraphy in the majority of wells the change in gas content with depth between the different units and the wells was used to identify domains of different gas gradients which could relate to differing gas saturations and geological setting the well profiles and gas gradients were analysed against available open file coal quality data without strong correlation to rank or type parameters the majority of very high gas gradient values occur in coals within or above the tangalooma sandstone suggesting that it forms a regional scale barrier both to possible gas migration from underlying and higher rank coals and to meteoric and biogenic recharge from above increased ethane values in the upper taroom and tangalooma csg support this interpretation alternatively this distribution may be the result of alternating adsorption desorption cycles linked to burial and uplift the wells containing the highest mean gas gradients span a range of subtle rank and structural domains but generally occur in structural highs under topographic lows with hydrostatic head wells from smaller scale anticlines not associated with topographic surface lows mainly exhibit lower mean gas gradients the study significantly expands the number of published gas content trends and proposes several factors influencing their formation and geographical distribution the results form the basis for future targeted sampling to test for gas origins migration retention and biogenic recharge processes within the surat basin

geochemical mapping of magmatic gas water rock interactions in the aquifer of mount etna volcano abstract systematic analysis of major and minor elements in groundwaters from springs and wells on the slopes of mt etna in 1995 1998 provides a detailed geochemical mapping of the aquifer of the volcano and of the interactions between magmatic gas water bodies and their host rocks strong spatial correlations between the largest anomalies in pco2 ph and alkalinity k rb mg ca and sr suggest a dominating control by magmatic gas co2 and consequent basalt leaching by acidified waters of the shallow meteoric etnean aquifer most groundwaters displaying this magmatic type interaction discharge within active faulted zones on the s sw and e lower flanks of the volcanic pile but also in a newly recognised area on the northern flank possibly tracking a main n s volcano tectonic structure in the same time the spatial distribution of t c tds na li cl and b allows us to identify the existence of a deeper thermal brine with high salinity high content of b cl and gases co2 h2s ch4 and low k na ratio which is likely hosted in the sedimentary basement this hot brine reaches the surface only at the periphery of the volcano near the village of paterno where it gives rise to mud volcanoes called salinelle di paterno however the contribution of similar brines to shallower groundwaters is also detected in other sectors to the w bronte maletto sw adrano and se acireale suggesting its possible widespread occurrence beneath etna this thermal brine is also closely associated with hydrocarbon fields all around the volcano and its rise generally masked by the high outflow of the shallow aquifer may be driven by the ascent of mixed sedimentary magmatic gases through the main faults cutting the sedimentary basement

the importance of shale composition and pore structure upon gas storage potential of shale gas reservoirs abstract the effect of shale composition and fabric upon pore structure and ch 4 sorption is investigated for potential shale gas reservoirs in the western canadian sedimentary basin wcsb devonian mississippian d m and jurassic shales have complex heterogeneous pore volume distributions as identified by low pressure co 2 and n 2 sorption and high pressure hg porosimetry thermally mature d m shales 1 6 2 5 vro have dubinin radushkevich d r co 2 micropore volumes ranging between 0 3 and 1 2 cc 100 g and n 2 bet surface areas of 5 31 m 2 g jurassic shales which are invariably of lower thermal maturity ranging from 0 9 to 1 3 vro than d m shales have smaller d r co 2 micropore volumes and n 2 bet surface areas typically in the range of 0 23 0 63 cc 100 g co 2 and 1 9 m 2 g n 2 high pressure ch 4 isotherms on dried and moisture equilibrated shales show a general increase of gas sorption with total organic carbon toc content methane sorption in d m shales increases with increasing toc and micropore volume indicating that microporosity associated with the organic fraction is a primary control upon ch 4 sorption sorption capacities for jurassic shales however can be in part unrelated to micropore volume the large sorbed gas capacities of organic rich jurassic shales independent of surface area imply a portion of ch 4 is stored by solution in matrix bituminite solute ch 4 is not an important contributor to gas storage in d m shales structural transformation of d m organic matter has occurred during thermal diagenesis creating and or opening up microporosity onto which gas can sorb as such d m shales sorb more ch 4 per weight percent wt toc than jurassic shales inorganic material influences modal pore size total porosity and sorption characteristics of shales clay minerals are capable of sorbing gas to their internal structure the amount of which is dependent on clay type illite and montmorillonite have co 2 micropore volumes of 0 78 and 0 79 cc 100 g n 2 bet surface areas of 25 and 30 m 2 g and sorb 2 9 and 2 1 cc g of ch 4 respectively dry basis a reflection of microporosity between irregular surfaces of clay platelets and possibly related to the size of the clay crystals themselves mercury porosimetry analyses show that total porosities are larger in clay rich shales compared to silica rich shales due to open porosity associated with the aluminosilicate fraction clay rich sediments low si al ratios have unimodal pore size distributions

geochemistry of rainfall at stromboli volcano aeolian islands isotopic composition and plume rain interaction the chemical and isotopic compositions of the precipitation at stromboli island italy were investigated between october 2003 and october 2005 we employed a rain gauge network designed to cover the range in exposures and elevations of the volcanic edifice the hydrogen and oxygen isotopic ratios vary greatly on a seasonal basis and correlate with air temperature deuterium excess values show a positive correlation with altitude no direct contribution of volcanogenic h or o is evident in the isotopic composition of the rainwater the chemical composition of the rainwater is principally controlled by the sea aerosol contribution at the coastal sites whereas it is significantly influenced by volcanic activity near the summit vents interaction with volcanic acid gases is indicated by the ph which is usually 1 2 units lower near the craters than at the coastal sites the s cl cl f and s f molar ratios in rainwater 1 5 km from the craters are consistent with those measured in the volcanic plume using other methods diffusive tubes and fourier transform infrared spectroscopy rising of undegassed magmas changes these molar ratios because of the differential degassing of sulphur chlorine and fluorine from the magma we therefore propose that the chemical composition of precipitation within 1 5 km of the craters provides additional information that is useful for monitoring volcanic activity at stromboli island moreover this paper presents estimates of the fluxes of f cl s na k ca and mg to the soil that could be useful for geochemical studies on groundwater

natural and anthropogenic factors affecting groundwater quality of an active volcano mt etna italy abstract new geochemical data on dissolved major and minor constituents in 276 groundwater samples from etna aquifers reveal the main processes responsible for their geochemical evolution and mineralisation this topic is of particular interest in the light of the progressive depletion of water resources and groundwater quality in the area multivariate statistical analysis reveal 3 sources of solutes a the leaching of the host basalt driven by the dissolution of magma derived co2 b mixing processes with saline brines rising from the sedimentary basement below etna c contamination from agricultural and urban wastewaters the last process highlighted by increased concentrations of so4 no3 ca f and po4 is more pronounced on the lower slopes of the volcanic edifice associated with areas of high population and intensive agriculture however this study demonstrates that natural processes a and b are also very effective in producing highly mineralised waters which in turn results in many constituents b v mg exceeding maximum admissible concentrations for drinking water

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

surface faulting accompanying the borah peak earthquake central idaho the ms 7 3 borah peak earthquake that struck central idaho on october 28 1983 was one of the strongest historic earthquakes in the intermountain seismic belt much of the 34 km long northwest trending zone of fault scarps and surface ruptures that formed during the earthquake follows holocene and upper pleistocene scarps of the lost river fault throw along the new fault scarps averages 0 8 m exceeds 1 0 m along 43 of their length and attains a maximum of 2 7 m along the broad and complex zone of deformation in the southern section the net slip was normal sinistral averaging 17 cm lateral slip for 100 cm of dip slip the preferred nodal plane from the focal mechanism strikes n22 w dips 59 sw and suggests a much larger component of strike slip than do the geologic data

porosity of coal and shale insights from gas adsorption and sans usans techniques two pennsylvanian coal samples spr326 and spr879 in1 and two upper devonian mississippian shale samples mm1 and mm3 from the illinois basin were studied with regard to their porosity and pore accessibility shale samples are early mature stage as indicated by vitrinite reflectance ro values of 0 55 for mm1 and 0 62 for mm3 the coal samples studied are of comparable maturity to the shale samples having vitrinite reflectance of 0 52 spr326 and 0 62 spr879 in1 gas n2 and co2 adsorption and small angle and ultrasmall angle neutron scattering techniques sans usans were used to understand differences in the porosity characteristics of the samples the results demonstrate that there is a major difference in mesopore 2 50 nm size distribution between the coal and shale samples while there was a close similarity in micropore 2 nm size distribution micropore and mesopore volumes correlate with organic matter content in the samples accessibility of pores in coal is pore size specific and

mudstone compaction and its influence on overpressure generation elucidated by a 3d case study in the north sea mudstones are one of the least permeable rocks in most sedimentary sequences accordingly they can act as seals for fluid flow leading to abnormal overpressures nevertheless mudstone compaction and related permeability and porosity decrease are not adequately described in current basin modelling software because only mechanical compaction is taken into account in reality however clay minerals undergo severe chemical diagenesis which certainly influences petrophysical properties and compaction in this context a mathematical approach which has been originally developed in soil mechanics has been adapted to basin modelling the underlying mathematical equations are carefully explained in the text in the basic equation the compression coefficient is a function of void ratio and effective stress using these equations overpressure can be predicted by using petroleum systems modelling techniques this is shown for a real 3d case study in the north sea in which strong overpressure occurs a compaction model for mudstones that depends strongly on the clay content of the individual stratigraphic units is used for the calibration of porosities in the 3d case study in addition a chemical compaction model that reduces porosities by using a kinetic reaction is used for the deeper part of the basin where mechanical compaction processes are less important the pressure generation process depends strongly on permeability and compressibility of the porous medium therefore the use of mudstone compaction and permeability models is sufficient to produce pore overpressures in the case studied abnormal overpressures are generated during burial together with the petroleum generation process the mechanical and chemical compaction mechanisms ensure that the pressures are preserved in the deeper part of the basin

selenium mobilization in soils due to volcanic derived acid rain an example from mt etna volcano sicily abstract the significant amounts of selenium se emitted by volcanoes may have important impact on human health due to the narrow range between nutrition requirement and toxic effects for living organisms upon se exposure although soils play a key role in determining the level in food and water and thereby human health little is known about the behaviour of se in volcanic soils in this work we evaluated the se release during rainwater soil interaction under controlled conditions using soils collected on the flanks of etna volcano and synthetic rain selenium concentrations in soil leachate solutions displayed a spatial distribution which cannot be explained by plume deposition total se soil concentrations or the presence of fe oxides instead al compounds and to a minor extent som were identified as the active phases controlling the selenate mobilization during interaction with sulphate containing rainwater this shows the importance of soils as reactive interfaces selenium is mobilized when volcanic derived acid rain interacts with poorly developed soils close to the crater this geogenic process might influence the chemical composition of groundwater and as a result human health

coal petrology and coal seam gas contents of the walloon subgroup surat basin queensland australia abstract core exploration and appraisal drilling over the last four years have targeted the juandah upper and taroom lower coal measures of the middle jurassic walloon subgroup of the injune creek group these wells have shown that the high volatile bituminous perhydrous coals of the walloon subgroup have gas contents of between 1 and 14 m 3 t and some wells have encountered gas flows at rates of over 30 000 m 3 day this recent work has confirmed the initial supposition that the coals within the walloon subgroup contain sufficient quantities of gas to be economically viable as a coal seam gas source coal volumes depth and structure have also been confirmed from the initial work what has become apparent during this work is the variability in gas content across each of the seams in the juandah and taroom coal measures and the variability in coal petrographic composition of these two units are controlled by many factors what has also become apparent is that the taroom coal measures have a lower average gas content than the overlying juandah coal measures the obvious conclusion is that the difference in gas content is related to a difference in coal petrology not only do the gas contents of these coal intervals differ their gas adsorption capacities also differ with the taroom coal measures coals displaying on average lower gas content and lower gas adsorption capabilities again the obvious cause would be coal petrological differences but the juandah and taroom coal measures coals have similar maceral percentages an understanding of the relationship between gas desorption gas adsorption and coal composition is vital in determining which areas in the basin offers the most economically viable targets for the commercialisation of coal seam gas in the surat basin

constraints on the frequency magnitude relation and maximum magnitudes in the uk from observed seismicity and glacio isostatic recovery rates summary earthquake populations have recently been shown to have many similarities with critical point phenomena with fractal scaling of source sizes energy or seismic moment corresponding to the observed gutenberg richter g r frequency magnitude law holding at low magnitudes at high magnitudes the form of the distribution depends on the seismic moment release rate mand the maximum magnitude m max the g r law requires a sharp truncation at an absolute maximum magnitude for finite m i n contrast the gamma distribution has an exponential tail which allows a soft or credible maximum to be determined by negligible contribution to the total seismic moment release here we apply both distributions to seismic hazard in the mainland uk and its immediate continental shelf constrained by a mixture of instrumental historical and neotectonic data tectonic moment release rates for the seismogenic part of the lithosphere are calculated from a flexural plate model for glacio isostatic recovery constrained by vertical deformation rates from tide gauge and geomorphological data earthquake focal mechanisms in the uk show near vertical strike slip faulting with implied directions of maximum compressive stress approximately in the nnw sse direction consistent with the tectonic model maximum magnitudes are found to be in the range 6 3 7 5 for the g r law or 7 0 8 2 m l for the gamma distribution which compare with a maximum observed in the time period of interest of 6 1 m l the upper bounds are conservative estimates based on 100 per cent seismic release of the observed vertical neotectonic deformation glacio isostatic recovery is predominantly an elastic rather than a seismic process so the true value of m max is likely to be nearer the lower end of the quoted range

porosity and permeability characterization of coal a micro computed tomography study abstract a unique contrast agent technique using x ray micro computed tomography micro ct was developed for studying micrometer sized features in coal the technique allows for the visualization of coal fractures not visible with conventional imaging methods a late permian medium volatile bituminous coal from moura coal mine was imaged and the resulting three dimensional coal cleat system was extracted for fluid flow simulations the results demonstrate a direct relationship between coal lithotype and permeability i e bright coals offer more permeability than dull coals however there was no direct relationship between porosity and permeability for any given lithotype scanning electron microscope and energy dispersive spectrometry sem eds together with x ray diffraction xrd methods were used for identifying mineral matter at high resolution after segmentation of the micro ct image mineral phase was removed from the segmented data and it was found that permeability was significantly improved by increasing cleat void space and connectivity suggesting that enhanced recovery methods could target de mineralization techniques overall only the epigenetic mineral phases in the bright band influenced permeability while lithotype had a stronger impact on permeability than porosity coal lithotype and mineralization are important evaluation criteria when considering coal seam gas development sites

late quaternary faulting and thermoluminescence dating of the east cache fault zone north central utah the east cache fault zone ecfz the southernmost of five en echelon quaternary normal faults between the wasatch and teton faults displays evidence of two large paleoearthquakes in the last 15 000 years 15 ka stratigraphic data from a trench on the central segment of the ecfz are augmented with one radiocarbon date the regional radiocarbon chronology and 14 thermoluminescence tl age estimates of the 14 tl analyses performed by alpha analytic inc only 8 satisfied our criteria for statistical acceptability 20 per cent coefficient of variation 50 per cent extrapolation to residual tl level the tl age estimates broadly bracket the earlier faulting event at between 8 7 1 0 and 17 4 3 0 ka and the later event at between 2 5 0 5 and 8 7 1 0 ka one radiocarbon age further constrains the earlier event to be younger than 15 540 130 yr bp correlation of local quaternary deposits to the regional radiocarbon chronology provides indirect but more tightly limiting age constraints of ca 4 to ca 7 ka for the later event and ca 13 ka to 15 540 130 yr bp for the earlier event both events had small vertical displacements at the trench site 0 8 to 1 8 m but the cumulative net vertical tectonic displacement elsewhere is up to 4 2 m suggesrive of m s 6 9 to 7 1 paleoearthquakes single event displacements and the extent of fault scarps suggest that these two paleoearthquake ruptures were probably limited to the 20 kin long central segment of the east cache fault zone near logan utah the elapsed time since the most recent event on the central segment ca 4 to ca 7 ka is somewhat less than the estimated recurrence interval between the latest two paleoearthquake 8 6 3 0 ka however comparison of only a single poorly constrained recurrence interval with the elapsed time does not result in a confident assessment of future earthquake potential

statistical relations among earthquake magnitude surface rupture length and surface fault displacement abstract in order to refine correlations of surface wave magnitude fault rupture length at the ground surface and fault displacement at the surface by including the uncertainties in these variables the existing data were critically reviewed and a new data base was compiled earthquake magnitudes were redetermined as necessary to make them as consistent as possible with the gutenberg methods and results which make up much of the data base measurement errors were estimated for the three variables for 58 moderate to large shallow focus earthquakes regression analyses were then made utilizing the estimated measurement errors the regression analysis demonstrates that the relations among the variables magnitude length and displacement are stochastic in nature the stochastic variance introduced in part by incomplete surface expression of seismogenic faulting variation in shear modulus and regional factors dominates the estimated measurement errors thus it is appropriate to use ordinary least squares for the regression models rather than regression models based upon an underlying deterministic relation in which the variance results primarily from measurement errors significant differences exist in correlations of certain combinations of length displacement and magnitude when events are grouped by fault type or by region including attenuation regions delineated by evernden and others estimates of the magnitude and the standard deviation of the magnitude of a prehistoric or future earthquake associated with a fault can be made by correlating m s with the logarithms of rupture length fault displacement or the product of length and displacement fault rupture area could be reliably estimated for about 20 of the events in the data set regression of m s on rupture area did not result in a marked improvement over regressions that did not involve rupture area because no subduction zone earthquakes are included in this study the reported results do not apply to such zones

gas storage potential and electrohydraulic discharge ehd stimulation of coal seam interburden from the surat basin this paper evaluates the potential methane storage capacity of six clay rich interburden rock samples from coal seam gas csg wells in the surat basin australia clay minerals identified in all samples included kaolinite illite smectite and illite smectite mixed layers the total organic carbon concentrations in these interburden rocks ranged from 0 66 1 19 wt and thus these rocks can be classified as fair to good hydrocarbon source rocks the effective porosity of the rocks determined from mercury intrusion porosimetry and helium pycnometry varied from 6 8 to 12 5 and included volumes of micropores and mesopores the adsorption isotherm results indicated that the average adsorption capacity of six interburden was 3 64 cm 3 g a value corresponding to approximately 20 that of surat basin coal based on the clay compositions and porosity of the samples the permeability of these surat interburden rocks is estimated to be 5 nano darcy using yang and aplin s empirical correlation which was too low for reliable measurement in our laboratory core flooding apparatus even with a differential pressure of 10 bar applied over a shortened 20 mm length core however after stimulation by electrohydraulic discharge ehd shockwaves the permeability of one of the interburden samples s2 increased to 0 6 0 11 md due to development of fractures and new pores by the ehd stimulation we characterised the development of the fractures after ehd shockwaves using x ray computer tomography the findings of this study suggest that dynamic shockwaves such as those generated by ehd have potential to increase permeability of soft and clay rich interburden layers in csg reservoirs and other layered reservoirs this potentially opens these ultra tight gas resources to exploitation and recovery

insights into pore scale controls on mudstone permeability through resedimentation experiments at a given porosity mudstone permeability increases by an order of magnitude for clay contents ranging from 57 to 36 2 m this increase in vertical permeability results from a dual porosity system that develops through three mechanisms 1 silt bridging preserves large pore throats 2 stress bridges inhibit clay particle alignment and 3 local clay particle compression within stress bridges alters pore throat size distribution uniaxial consolidation experiments on resedimented clay silt mixtures illuminate how permeability varies as a function of clay fraction during burial backscattered electron microscope images show that silty mixtures have larger pore throats and fewer aligned clay particles than do more clay rich mixtures we describe the permeability of clay silt mixtures with a geometric mean model our method provides a promising framework for modeling of mudstone permeability as a function of clay fraction and porosity how permeability and consolidation evolve during burial affects the ability of mudstones to seal co2 and hydrocarbons in the subsurface how mudstones behave as gas reservoirs and under what conditions mudstones will be overpressured dual porosity systems have fundamentally different transient flow and solute transport behaviors

gas and particle emissions from soufriere hills volcano montserrat west indies characterization and health hazard assessment the soufriere hills volcano montserrat erupting since 18 july 1995 intensified its degassing in early 1996 with the continuing growth of the lava dome inside the summit crater during this period of increased activity between 11 and 18 march 1996 we measured gases and particles within the visible plume to determine whether at that time it posed a health risk to the population of plymouth the capital town which is 5 km southwest downwind and was then still occupied gravimetric measurements were made of total suspended particles tsp and particles having an aerodynamic diameter of less than 10 m pm10 measurements were made of sulphur dioxide so2 hydrochloric acid hcl hydrofluoric acid hf nitric acid hno3 acetic acid ch3cooh formic acid hcooh and particulate sulphate so4 2 chloride cl nitrate no3 fluoride f methanesulphonate ch3so3 acetate ch3coo formate hcoo ammonium nh4 sodium na and acidity h trace metals having human health implications chromium cr nickel ni cobalt co copper cu zinc zn arsenic as selenium se cadmium cd tin sn mercury hg and lead pb were also determined mean concentrations of hcl so2 and hf obtained in the town of plymouth were 14 0 5 9 and 0 8 ppbv respectively corresponding concentrations in the mixed plume on the crater edge were 533 168 and 22 ppbv there were no direct emissions of hno3 although nitrate was detected in coarse particles at the source higher concentrations of ch3cooh and hcooh were measured close to the crater mean tsp and pm10 were 64 and 15 g m 3 in plymouth and 455 and 47 g m 3 on the upper volcano slope aerosols were highly acidic at the source but rapidly neutralised during transport trace metals were enriched in the aerosol relative to crater surface material the concentrations of the acid gases sulphur dioxide in particular and particles were found to be too small to pose a health hazard at the time of these measurements when relatively modest volcanic activity was occurring

relationships between earthquake magnitude source geometry and slip mechanism abstract the empirical relationships between source area source length source width and magnitude m s are investigated for globally distributed earthquakes of different slip mechanism types a total of nearly 400 events having magnitudes approximately between 4 5 and 8 5 were considered the analyses of specially selected events outlined that the regional setting has no influence on the relationships between m s and source dimensions as well as between rupture length and width instead they depend on the slip mechanism type strike slip reverse and normal oblique slip as mechanisms change from strike slip to oblique slip and further from oblique slip to reverse and normal slip sources of similar length size exhibit increasing magnitudes in steps of 0 8 1 6 in the overall mentioned spectrum of the mechanism types whereas sources of similar areas correspond to the different slip type events with magnitudes increasing in steps of 0 5 0 8 source widths increase by about three times for earthquakes of equal rupture length when the mechanism changes from strike slip to reverse and normal slip therefore it can be concluded that sources of equal length have different areas and length width ratios for various types of mechanism accordingly stress drop may be larger for strike slip sources than for sources with prevailing vertical displacement the regressions of rupture dimensions on surface wave magnitude for different single slip mechanism types restricted in most cases to the magnitude range between 5 5 and 8 0 are strongly correlated having standard deviations of 0 15 0 25 magnitude units corresponding regression coefficients are different at 95 level of significance for different slip mechanism types of each pair of correlated parameters the single slip type regressions have smaller standard deviations and higher correlation coefficients than the all slip type regressions this observation validates the conclusion about strong dependencies of source dimensions and surface wave magnitudes on slip mechanism type the results can be used to evaluate the event magnitude source area length width and mechanism type when any two of these parameters are known

micro and nano size pores of clay minerals in shale reservoirs implication for the accumulation of shale gas abstract a pore is an essential component of shale gas reservoirs clay minerals are the adsorption carrier second only to organic matter this paper uses the organic maturity test field emission scanning electron microscopy fe sem and x ray diffraction xrd to study the structure and effect of clay minerals on storing gas in shales results show the depositional environment and organic maturity influence the content and types of clay minerals as well as their structure in the three types of sedimentary facies in china clay minerals develop multi size pores which shrink to micro and nano size by close compaction during diagenesis micro and nano pores can be divided into six types 1 interlayer 2 intergranular 3 pore and fracture in contact with organic matter 4 pore and fracture in contact with other types of minerals 5 dissolved and 6 micro cracks the contribution of clay minerals to the presence of pores in shale is evident and the clay plane porosity can even reach 16 close to the contribution of organic matter the amount of clay minerals and pores displays a positive correlation clay minerals possess a strong adsorption which is affected by moisture and reservoir maturity different pore levels of clay minerals are mutually arranged thus essentially producing distinct reservoir adsorption effects understanding the structural characteristics of micro and nano pores in clay minerals can provide a tool for the exploration and development of shale gas reservoirs

seismotectonics of the guinean earthquake of december 22 1983 field geological and seismological investigations conducted after the guinean earth quake on december 22 1983 show a shallow dextral strike slip fault with a large normal component the nw se horizontal compressive stress deduced from this event is consistent with measurements made at other places in this region old fissures some of them reactivated during this earthquake show that this intraplate area cons titutes a localized weakness zone in the crust

variability of alkali and heavy metal fluxes released by mt etna volcano sicily between 1991 and 1995 abstract we regularly collected volcanic gases and aerosols at mt etna volcano over a long period 1991 1995 and measured their chemical composition by icp ms based on these data we present new evidence on the high volatility of both alkali and some heavy metals in contrast both lanthanides and actinides are not produced as significant gaseous compounds at magmatic temperatures and can be used as tracers of spattered materials all metals of each chemical family maintained systematic trends during the study period at both summit craters and effusive vents located in the valle del bove during the 1991 1993 eruption during the eruption we observed high metal enrichments at effusive vents these enrichments seem to be characteristic of the secondary degassing of a magma previously degassed under the summit area lower metal enrichments are recorded in aerosols sampled in summit crater plumes according to the primary degassing type occurring at these vents while a primary degassing type still occurs at both bocca nuova and voragine during the post eruptive period sud est crater exhibits a transition from primary to secondary type according to the variations of the volcanic activity level we confirm that the alkali metals fractionate systematically within their family as they cross the melt vapour interface the heavier members being always more enriched than the lighter ones in aerosols we also show that this fractionation is not related to the volcanic activity and the degassing type but seems to be a significant feature of the alkali family itself estimation of new emanation coefficients for rubidium caesium tin and thallium 0 07 0 15 0 50 and 21 respectively yields annual outputs around 1000 t yr 60 t yr 240 t yr and 1600 t yr respectively mount etna is a very important source of metals injected into the atmosphere contributing to the global volcanic budget about 16 for heavy metals and 19 for alkali metals in eruptive periods and only 2 and 4 respectively in quiet periods

determination of magnitudes of ancient earthquakes from dimensions of observed seismodislocations abstract equations to estimate the magnitude of ancient earthquakes where seismotectonic crustal deformations normal faults strike slip faults etc have been preserved in the epicentral region are presented the equations are based on the results of over one hundred earthquakes including 96 recent continental earthquakes in the magnitude range 5 2 8 7

surface faulting in the southern italian campania basilicata earthquake of 23 november 1980 the campania basilicata earthquake of 23 november 1980 was the largest ms 6 9 and most destructive earthquake that has occurred in this region of southern italy for over 100 years killing more than 3 000 people the consensus among seismologists geologists and earthquake engineers who have studied1 10 this event is in keeping with previous italian earthquakes that it did not produce faulting at the surface this has led to the establishment of a number of models2 3 11 13 requiring an unusual tectonic setting for the southern apennines however on a recent visit to the epicentral region of the earthquake may 1984 we discovered more than 10 km of surface faulting that is consistent with focal mechanisms for this event based on first motion polarities2 4 5 12 and long period waveform studies14 16 which show that it involved normal faulting with one nodal plane dipping at 60 towards the north east our observations of this the first well documented earthquake fault break to be reported in italy suggest that the deformation associated with earthquakes in the southern apennines takes place in the upper 10 15 km of the earth s crust on steep planar normal faults which break the surface as is widely observed in other areas of active extension outside italy

sweet chestnut castanea sativa leaves as a bio indicator of volcanic gas aerosol and ash deposition onto the flanks of mt etna in 2005 2007 sweet chestnut leaves castanea sativa collected from the flanks of mt etna volcano in 2005 2007 were analysed by inductively coupled plasma mass spectrometry to investigate the spatial and temporal variability of element concentrations the aim of this work was to determine whether these leaves are a bio indicator for volcanic gas aerosol and ash deposition and to gain new insights into the environmental effects of quiescent and eruptive volcanic plumes results show a positive correlation between sample variability in the concentration of elements in castanea sativa and enrichment factors of elements in the plume the spatial and temporal variability of chalcophilic elements as cd cu mo tl zn is consistent with prevailing winds transporting eruptive plumes to the south east of the summit resulting in enhanced plume deposition onto the flanks of the volcano similar spatial and temporal variability was found for the halide forming elements cs k rb and intermediate elements al co mn the spatial variability of chalcophilic intermediate and halide forming elements during quiescent periods was diminished relative to eruptive periods and could not be explained by plume deposition in contrast the concentrations of lithophilic elements ba ca mg sr did not show any clear spatial variability even during eruptive periods comparisons between enrichment factors for elements in castanea sativa and literature values for enrichment factors of the volcanic plume groundwater and lichen were made whilst castanea sativa offers insights into the spatial and temporal variability of deposition the species may not be a bio indicator for plume composition due to biological fractionation