natural spatial and temporal variations in groundwater chemistry in fractured sedimentary rocks scale and implications for solute transport abstract natural tracers major ions 18 o and o 2 were monitored to evaluate groundwater flow and transport to a depth of 20 m below the surface in fractured sedimentary primarily shale and limestone rocks large temporal variations in these tracers were noted in the soil zone and the saprolite and are driven primarily by individual storm events during nonstorm periods an upward flow brings water with high tds constant 18 o and low dissolved o 2 to the water table during storm events low tds variable 18 o and high dissolved o 2 water recharges through the unsaturated zone these oscillating signals are rapidly transmitted along fracture pathways in the saprolite with changes occurring on spatial scales of several meters and on a time scale of hours the variations decreased markedly below the boundary between the saprolite and less weathered bedrock variations in the bedrock units occurred on time scales of days and spatial scales of at least 20 m the oscillations of chemical conditions in the shallow groundwater are hypothesized to have significant implications for solute transport solutes and colloids that adsorb onto aquifer solids can be released into solution by decreases in ionic strength and ph the decreases in ionic strength also cause thermodynamic undersaturation of the groundwater with respect to some mineral species and may result in mineral dissolution redox conditions are also changing and may result in mineral dissolution precipitation the net result of these chemical variations is episodic transport of a wide range of dissolved solutes or suspended particles a phenomenon rarely considered in contaminant transport studies

chemical and isotopical characterisation of fluid manifestations of ischia island italy abstract between 1994 and 1995 gas samples from fumaroles and thermal waters were collected on ischia island the chemical composition of the shallow and deep natural hydrothermal fluids discharged is related to the main hydrological and lithological characteristics of the rock formations present in the reservoir a biphase reservoir liquid gas is identified where the dominant liquid has a temperature of about 280 c on the basis of 13ctdc values it was possible to hypothesize a deep source characterised by carbon isotopic values varying from 0 to 3 these values are noticeably more positive with respect to those attributed to magmatic co2 13 c co 2 ranging from 5 to 8 thus suggesting a magmatic source modified by crustal contamination this hypothesis is supported by the carbon isotopic composition of co2 in sampled gases which varied from 0 to 5 the inferred isotopic value of carbon of magmatic co2 would then be about 2 the observed differences in c isotopic composition between fumarolic and magmatic gases would be caused by kinetic and or equilibrium fractionation processes these processes would cause a fractionation of 13c of deep co2 towards more negative values down to 5 actually co2 removal or addition processes caused by the interaction between deep gases and shallow hydrothermal waters are likely to be responsible for the different chemical and isotopic compositions of gaseous emissions for these reasons and on the basis of the homogeneity of geothermometric values the existence of a single large reservoir that feeds all of the fluids discharged at ischia island can be hypothesised based on acquired data a new geochemical model of the geothermal system of ischia island is proposed

groundwater recharge to ophiolite aquifer in north oman constrained by stable isotopes and geochemistry the current study employs geochemical and isotopic tools to understand hydrochemical and recharge processes characterizing ophiolite aquifer in north oman in conjunction with the hajar super group hsg aquifer a total of 57 samples were analyzed for major ions and stable isotopes 2h and 18o the geochemical composition of groundwater indicates that water rock interaction and mixing are the main processes controlling groundwater chemistry groundwater in the hsg is characterized by carbonate minerals dissolution contrary to the groundwater in the ophiolites where silicates dissolution dominates this results in differences in the groundwater chemical composition in the two systems isotopic characteristics of precipitation collected during the study period indicate two main moisture sources from the indian ocean and the mediterranean sea groundwater 2h and 18o values suggest two recharge sources to the ophiolite aquifer lateral flow from the hsg and direct infiltration recharge from direct infiltration in the highlands which is depleted in 2h and 18o retains the same isotopic signature of precipitation whereas that in the low land substantially reflects an evaporation effect

coupled modeling of hydrogeochemical and electrical resistivity data for exploring the impact of recharge on subsurface contamination 1 the application of geophysical methods in particular electrical resistivity measurements may be useful for monitoring subsurface contamination however interpreting geophysical data without additional data and without considering the associated hydrogeochemical processes is challenging since the geophysical response is sensitive to not only heterogeneity in rock properties but also to the saturation and chemical composition of pore fluids we present an inverse modeling framework that incorporates the simulation of hydrogeochemical processes and time lapse electrical resistivity data and apply it to various borehole and cross borehole data sets collected in 2008 near the s 3 ponds at the u s department of energy s oak ridge integrated field research challenge site where efforts are underway to better understand freshwater recharge and associated contaminant dilution our goal is to show that the coupled hydrogeochemical geophysical modeling framework can be used to 1 develop a model that honors all the available data sets 2 help understand the response of the geophysical data to subsurface properties and processes at the site and 3 allow for the estimation of petrophysical parameters needed for interpreting the geophysical data we present a series of cases involving different data sets and increasingly complex models and find that the approach provides useful information about soil properties recharge related transport processes and the geophysical response spatial heterogeneity of the petrophysical model can be described sufficiently with two layers and its parameters can be estimated concurrently with the hydrogeochemical parameters for successful application of the approach the parameters of interest must be sensitive to the available data and the experimental conditions must be carefully modeled

the faroe shetland basin a regional perspective from the paleocene to the present day and its relationship to the opening of the north atlantic ocean the faroe shetland basin is located offshore nw scotland on the se margin of the atlantic ocean and comprises numerous sub basins and intra basin highs that are host to a number of significant hydrocarbon discoveries the principal hydrocarbon discoveries are in palaeocene eocene strata though earlier ones are known and therefore their existence is intimately linked to the opening and evolution of the north atlantic from 54 ma the final rifting and separation of greenland from eurasia is commonly attributed to the arrival of a mantle plume which impacted beneath greenland in the early tertiary moreover the ensuing plate separation is commonly described in terms of instantaneous unzipping of the north atlantic whereas in reality proto plate boundaries were more diffuse during their inception and the linked rift system including connections with the arctic which we see today was not established until late palaeogene early neogene time from a regional analysis of ocean basin development including the stratigraphic record on the adjacent continental margins the significance of the greenland iceland faroe ridge and the age and role of iceland we propose a dual rift model whereby north atlantic breakup was only partial until the oligo miocene with true final breakup only being achieved when the reykjanes and kolbeinsey ridges became linked as final breakup coincides with the appearance of iceland this model negates the need for a plume to develop the north atlantic with rifting reliant on purely plate tectonic mechanisms lithospheric thinning and variable decompressive upper mantle melt along the rifts

surface motions and intraplate continental deformation in alaska driven by mantle flow the degree to which the lithosphere and mantle are coupled and contribute to surface deformation beneath continental regions remains a fundamental question in the field of geodynamics here we use a new approach with a surface deformation field constrained by gps geologic and seismicity data together with a lithospheric geodynamic model to solve for tractions inferred to be generated by mantle convection that 1 drive extension within interior alaska generating southward directed surface motions toward the southern convergent plate boundary 2 result in accommodation of the relative motions between the pacific and north america in a comparatively small zone near the plate boundary and 3 generate the observed convergence within the north american plate interior in the mackenzie mountains in northwestern canada the evidence for deeper mantle influence on surface deformation beneath a continental region suggests that this mechanism may be an important contributing driver to continental plate assemblage and breakup

experimental evidence on formation of imminent and short term hydrochemical precursors for earthquakes abstract the formation of imminent hydrochemical precursors of earthquakes is investigated by the simulation for water rock reaction in a brittle aquifer sixty one soaking experiments were carried out with granodiorite and trachyandesite grains of different sizes and three chemically distinct waters for 6 to 168 h the experimental data demonstrate that water rock reaction can result in both measurable increases and decreases of ion concentrations in short times and that the extents of hydrochemical variations are controlled by the grain size dissolution and secondary mineral precipitation as well as the chemistry of the rock and groundwater the results indicate that water rock reactions in brittle aquifers and aquitards may be an important genetic mechanism of hydrochemical seismic precursors when the aquifers and aquitards are fractured in response to tectonic stress

gplates building a virtual earth through deep time gplates is an open source cross platform plate tectonic geographic information system enabling the interactive manipulation of plate tectonic reconstructions and the visualization of geodata through geological time gplates allows the building of topological plate models representing the mosaic of evolving plate boundary networks through time useful for computing plate velocity fields as surface boundary conditions for mantle convection models and for investigating physical and chemical exchanges of material between the surface and the deep earth along tectonic plate boundaries the ability of gplates to visualize subsurface 3 d scalar fields together with traditional geological surface data enables researchers to analyze their relationships through geological time in a common plate tectonic reference frame to achieve this a hierarchical cube map framework is used for rendering reconstructed surface raster data to support the rendering of subsurface 3 d scalar fields using graphics hardware accelerated ray tracing techniques gplates enables the construction of plate deformation zones regions combining extension compression and shearing that accommodate the relative motion between rigid blocks users can explore how strain rates stretching shortening factors and crustal thickness evolve through space and time and interactively update the kinematics associated with deformation where data sets described by geometries points lines or polygons fall within deformation regions the deformation can be applied to these geometries together these tools allow users to build virtual earth models that quantitatively describe continental assembly fragmentation and dispersal and are interoperable with many other mapping and modeling tools enabling applications in tectonics geodynamics basin evolution orogenesis deep earth resource exploration paleobiology paleoceanography and paleoclimate

catastrophic collapse at stratovolcanoes induced by gradual volcano spreading unlike ordinary mountains which are formed by slow uplift and erosion volcanoes are constructed rapidly as a consequence many are liable to massive flank failures leading to debris avalanches for example at mount st helens in 1980 such failures occur worldwide about once every 25 years ref 1 and even small ones can present a major hazard in particular if far reaching tsunamis are generated as at mayu yama in 1792 ref 2 previous work has tended to emphasize differences in eruption style associated with flank failure2 but here we focus on the fundamental structural causes of failure most volcanic failures are generated by magmatic intrusion and flank spreading3 we present evidence however that mombacho volcano in nicaragua experienced a previously unrecognized type of failure triggered by sub volcanic basement spreading notably collapses related to basement spreading do not require that the volcano be magma tically active and thus flank failure may pose a significant risk even at inactive volcanoes which are rarely monitored

cenozoic tectonic and thermal history of the nenana basin central interior alaska new constraints from seismic reflection data fracture history and apatite fission track analyses the nenana basin of interior alaska forms a segment of the diffuse plate boundary between the bering and north american plates and is located within a complex zone of crustal scale strike slip deformation that accommodates compressional stresses in response to oblique plate convergence to the south the basin is currently the focus of new oil and gas exploration integration of seismic reflection and well data fracture data and apatite fission track analyses with regional data improves our understanding of the tectonic development of this continental strike slip basin the nenana basin formed during the late paleocene as a 13 km wide half graben affected by regional intraplate magmatism and localized crustal thinning across the minto fault in south central alaska the basin was uplifted and exhumed along this faulted margin in the early eocene through to late oligocene in response to oblique subduction along the southern alaska margin this event resulted in the removal of up to 1 5 km of late paleocen

a comprehensive study of pumice formation and dispersal the cretaio tephra of ischia italy the cretaio tephra is a small volume 0 02 km3 pumice deposit on the island of ischia in italy it was erupted during historical time and is associated with a tuff ring dome complex extruded along a n s trending normal fault system bordering the east side of the mt epomeo resurgent block 14c ages of the deposit average 1860 a b p which is in agreement with the potsherds found in paleosols underlying and overlying the deposit the eruption sequence consists of 7 members most of these members are pumice fall deposits one is an ash and pumice fallout and another is a surge bed the tephra have a trachytic phonolitic composition all chemical characteristics including major and trace elements and sr isotope composition are homogeneous throughout the sequence the vesicularity of pumice clasts does not show any systematic change the erupted magma had the same amount of volatiles the same flux and vesicle growth behavior throughout the eruption sequence grain size analyses of 90 tephra samples representative of all the members at variable distance from the supposed vent have been processed using the sequential fragmentation transport theory in order to define the effects of eruptive fragmentation and subsequent transport on the particle sizes distribution four significant subpopulations have been identified and related to transport mechanisms

simple shearing block resurgence in caldera depressions a model from pantelleria and ischia abstract similar resurgent blocks occur in caldera depressions at the islands of pantelleria and ischia the two blocks which are tilted show similar deformation patterns and similar distributions of volcanic vents related to resurgence the remaining parts of the floors of the two calderas are not deformed similarities between the two features are so striking that the resurgence mechanism must have been alike a dynamic model for resurgence is presented and called simple shearing block resurgence the triggering mechanism is an increase of the magmatic pressure in the upper part of a shallow magma chamber which results in a vertical direction of the maximum stress applied on the roof rocks the block is first defined by high angle inland dipping marginal detachments and then deformed through a simple shearing mechanism reverse faults on its mostly uplifted side determine an horizontal shortening of the block which is balanced on the opposite side by normal faults oblique movements take place along the other two sides due to this distribution of the stress around the block magmas can reach the surface only through the extensional faults on the less uplifted side

tectonic block motion and glacial isostatic adjustment in southeast alaska and adjacent canada constrained by gps measurements 1 we use data from campaign and continuous gps sites in southeast alaska and the neighboring region of canada to constrain a regional tectonic block model that estimates block angular velocities and derives a self consistent set of fault slip rates from the block motions present day tectonics in southeast alaska is strongly influenced by the collision of the yakutat block our model predicts a velocity of 50 3 0 8 mm a toward n22 9 0 6 w for that block our results suggest that the eastern edge of the yakutat block is deforming along this edge the fairweather fault accommodates a large portion of the pacific north america relative plate motion through 42 9 0 9 mm a of dextral slip further south along the queen charlotte fault our model predicts an average of 43 9 0 6 mm a of dextral slip and a southward increasing amount of transpression strain from the yakutat collision is transferred far to the east of the strike slip system this strain transfer causes the region north of glacier bay to undergo a clockwise rotation south of glacier bay and inboard of the queen charlotte fault a smaller but clearly defined clockwise rotation is observed the heterogeneous block motion north and south of glacier bay may indicate the area is undergoing internal deformation and could explain regional patterns of diffuse seismicity the northern cordillera of canada displays a small northeasterly motion our block model suggests that the entire southeastern alaska northwestern canada margin is mobile

a multiple pore region concept to modeling mass transfer in subsurface media abstract recent studies in soil science literature have strongly indicated the need to incorporate pore structures in near surface mass transport modeling there is increasing evidence suggesting that pore structures such as fractures and macropores facilitate the transport of water and solutes along a preferential flow path while water and solutes are moved into micropores and rock matrices concurrently this study presents a conceptual model a multiple pore region or multi region concept to account for pore structures as well as the resultant widely distributed pore water velocities in macroporous media pore regions can either be physically identified as discrete features such as fractures and rock matrices or be experimentally determined by separation of water retention curves according to pore classification schemes a multi region mechanism is proposed to account for the effect of local scale and field scale heterogeneities on mass transport under variably saturated conditions two numerical codes for subsurface fluid flow and solute transport have been developed with the multi region concept in which a firstorder mass exchange model is adopted to simulate the redistribution of pressure heads and solute concentrations among pore regions the computer codes are used to demonstrate the applicability of the concept to fractured porous media and to test a three pore region hypothesis using laboratory soil column tracer injection data based upon the parameters obtained from fitting multi region and mobile immobile models to these data we successfully demonstrated that the former model has the advantage of maintaining consistent conceptual models over the latter under variably saturated conditions

cyclical slope instability and volcanism related to volcano tectonism in resurgent calderas the ischia island italy case study abstract the results of a detailed stratigraphic study carried out in the areas located to the east and south west of mt epomeo at ischia are presented and compared with those of previous geological archaeological and historical investigations to show the relationships among caldera resurgence volcanism and slope instability in the past 5 5 ka resurgence at ischia began at about 30 ka b p and occurred through intermittent uplifting and tectonic quietness phases during the past 5 5 ka reactivation of faults and related volcanic activity was accompanied by emplacement of deposits generated by surface gravitational movements these deposits were generated in four main phases dated between 5 5 and 2 9 ka around 2 9 ka between 2 6 and 2 3 ka and between 2 3 and 1 9 ka respectively deposits formed by gravitational movements preceded and followed the emplacement of volcanic rocks testifying that slope instability was induced by vertical movements which also activated and or reactivated faults and fractures that fed volcanism the results of this study therefore suggest that although slope failure can occur as a consequence of a variety of factors resurgence has to be considered a factor inducing a particularly intense slope instability resurgence is accompanied by activation of faults and renewal of volcanism causing oversteepening of the slopes and generating seismicity that could trigger surface gravitational movements furthermore the availability of large amount of loose material rapidly accumulated along the slopes during eruptions favors landslide generation

magnetic modeling of the phlegraean volcanic district with extension to the ponza archipelago italy abstract a 3d modeling of the residual aeromagnetic anomalies of the area including the phlegraean volcanic district pvd campi flegrei caldera cfc and ischia and procida vivara islands and two volcanic islands of the ponza archipelago ventotene and s stefano has been carried out the observed residual anomalies have been reproduced with several large magnetized bodies located at 2 10 km depth in the crust a volcanological interpretation has been made possible only for those bodies that have been constrained by geological geothermal and other geophysical data the magnetized structures associated with cfc and ischia procida vivara ventotene and santo stefano islands have been interpreted as igneous bodies that may be solidified intrusions or magma reservoirs on the basis of magnetic data volcanological and magmatological history and geothermal heat flux distribution the existence of a partially solidified magma chamber is suggested at ischia a speculation shows that the magnetization intensity assumed for the magnetic bodies located at procida and south west of ventotene matches quite well with the calculated composition of a cooled residual magma resulting from crystallization processes within a chamber

present day geodynamics of the northern north american cordillera abstract diffuse continental deformation results from interactions at plate boundaries buoyancy forces generated by gradients in gravitational potential energy and loads applied to the base of the lithosphere using finite element models we calculate a deviatoric stress field associated with buoyancy forces and then perform an iterative inversion to calculate deviatoric stress fields associated with boundary forces in the northern north american cordillera our results reveal the presence of two distinct geodynamic domains in the outboard domain approximately equal magnitudes of boundary and buoyancy forces can account for the observed deformation along the aleutian megathrust in contrast large boundary forces related to subduction of the pacific and yakutat slabs dominate the force balance in south central alaska and combine with relatively small buoyancy forces to reproduce the observed kinematic indicators in the inboard domain encompassed by interior and northern alaska and western canada boundary and buoyancy forces alone cannot reproduce the observed deformation therefore we infer that deviatoric stresses due to basal tractions from a deeper mantle convection cell contribute to surface deformation in the inboard domain low effective lithospheric viscosity in south central alaska and the balancing effect of an independent geodynamic system driven by basal tractions in northern alaska combine to confine the anomalously large yakutat related boundary deviatoric stresses to south central alaska deviatoric stresses associated with flat slab subduction of the yakutat microplate are a factor of two greater than boundary force estimates for the andean and indian eurasian convergent margins where buoyancy and boundary forces are roughly equal in magnitude and dominate the force balance

the relationship between seismic deformation and deep seated gravitational movements during the 1997 umbria marche central italy earthquakes abstract this paper re evaluates the origin of some peculiar patterns of ground deformation in the central apennines observed by space geodetic techniques during the two earthquakes of the colfiorito seismic sequence on september 26th 1997 the surface displacement field due to the fault dislocation as modelled with the classic okada elastic formulations shows some areas with high residuals which cannot be attributed to non simulated model complexities the residuals were investigated using geomorphological analysis recognising the geologic evidence of deep seated gravitational slope deformations dsgsd of the block slide type the shape and direction of the co seismic ground displacement observed in these areas are correlated with the expected pattern of movement produced by the reactivation of the identified dsgsd at least a few centimetres of negative line of sight ground displacement was determined for the costa picchio mt pennino and mt prefoglio areas a considerable horizontal component of movement in the costa picchio dsgsd is evident from a qualitative analysis of ascending and descending interferograms the timing of the geodetic data indicates that the ground movement occurred during the seismic shaking and that it did not progress appreciably during the following months this work has verified the seismic triggering of dsgsd previously hypothesized by many researchers a further implication is that in the assessment of dsgsd hazard seismic input needs to be considered as an important cause of accelerated deformation

contamination of soil and groundwater by automatic transmission fluid site description and problem assessment abstract soil and groundwater beneath a region of a manufacturing plant are contaminated with automatic transmission fluid atf the extent of contamination was assessed by maximizing the use of real time data from soil core sampling and monitoring wells the number location and depth of cores and of monitoring wells were determined during the investigation based on 1 inspection and analysis of soil core samples immediately after each core was taken 2 physical and chemical measurements of core samples at the end of each day 3 measurements in monitoring wells at several stages during the investigation this approach differs significantly from the conventional approach of randomly placing wells through the hydrogeologic system soil cores were taken and monitoring wells installed at 53 locations the perched aquifer extends to about 13 ft and is comprised mainly of sandy materials which have spatial heterogeneity in size distribution and hydraulic properties about 208 000 33 000 gal of atf has spread over an area of about 64 000 ft 2 the region of atf contamination is comprised of three distinct and contiguous layers the center layer is about 2 6ft deep at its thickest point and extends to about 250ft at its widest point the soil in this zone is about 85 saturated with 133 000 21 000 gal of atf which has depressed the water table into the aquifer the top layer is about 14in thick and econtains about 50640 gal of atf held by capillary forces the amount of atf in this zone decreases with height above the center layer from about 85 saturation to residual saturation 20 the amount of atf in the deepest layer is near the residual saturation this layer is 1 0 0 5 ft thick and has 24 500 12 250 gal atf this investigative approach did not spread the atf to clean regions of the aquifer as could occur with conventional approaches and it provided the data needed to assess the problem and to design a cleanup plan a new approach is being used to recover the free atf at the site

global risk from extreme geophysical events threat identification and assessment in an increasingly interconnected world any single geophysical hazard is capable of having consequences far beyond the range of immediate physical effects most recently this was demonstrated by the 2004 asian tsunami which took the lives of citizens from 57 different nations and by hurricane katrina in august 2005 which raised fuel prices worldwide and contributed to a record uk trade deficit in the month following the devastation of new orleans on an altogether wider scale global geophysical events gges are natural phenomena capable of having wholesale deleterious consequences for the world s environment economy and society these may arise i due to a global physical effect such as an episode of severe planetary cooling in response to a volcanic super eruption or large comet or asteroid impact or ii as a result of subsidiary ramifications for the global economy and social fabric of a cataclysmic regional event such as an atlantic or pacific wide mega tsunami or a more spatially confined event at a strategically sensitive location for example the awaited major tokyo earthquake while very infrequent the wide ranging and potentially ruinous consequences of a gge for the well being of the international community make it essential that they are seriously considered within any comprehensive assessment of natural threats

thermochronology in southeast alaska and southwest yukon implications for north american plate response to terrane accretion abstract this study presents the first comprehensive dataset of low temperature thermochronology from 43 bedrock samples collected north of the active yakutat north american plate boundary our apatite and zircon u th he and fission track data reveal the cooling history of the inboard wrangellia composite terrane that is dominated by rapid cooling after late jurassic to early cretaceous arc magmatism followed by very little cooling and exhumation until today deformation resulting in rock exhumation due to the collision of the yakutat microplate is spatially very limited 20 30 km and is concentrated mainly in the chugach prince william terrane and rocks near the border ranges fault focused exhumation from greater depths of ca 10 km with very high rates 5 km myr is localized at the syntaxis region starting ca 10 ma and shifted south through time the rapid exhumation rates are explained by the development of strong feedbacks between tectonically driven surface uplift and erosion which started already before glaciation of the area the shift in the location towards the south is a consequence of continuous readjusting between tectonics and climate which is changing on local and global scales since the late miocene

new insights into late pleistocene explosive volcanic activity and caldera formation on ischia southern italy a new pyroclastic stratigraphy is presented for the island of ischia italy for the period 75 50 ka bp the data indicate that this period bore witness to the largest eruptions recorded on the island and that it was considerably more volcanically active than previously thought numerous vents were probably active during this period the deposits of at least 10 explosive phonolite to basaltic trachyandesite eruptions are described and interpreted they record a diverse range of explosive volcanic activity including voluminous fountain fed ignimbrite eruptions fallout from sustained eruption columns block and ash flows and phreatomagmatic eruptions previously unknown eruptions have been recognised for the first time on the island several of the eruptions produced pyroclastic density currents that covered the whole island as well as the neighbouring island of procida and parts of the mainland the morphology of ischia was significantly different to that seen today with edifices to the south and west and a submerged depression in the centre the largest volcanic event the monte epomeo green tuff megt resulted in caldera collapse across all or part of the island it is shown to comprise at least two thick intracaldera ignimbrite flow units separated by volcaniclastic sediments that were deposited during a pause in the eruption extracaldera deposits of the megt include a pumice fall deposit emplaced during the opening phases of the eruption a widespread lithic lag breccia outcropping across much of ischia and procida and a distal ignimbrite in south west campi flegrei during this period the style and magnitude of volcanism was dictated by the dynamics of a large differentiated magma chamber which was partially destroyed during the megt eruption this contrasts with the small volume holocene and historical effusive and explosive activity on ischia the timing and distribution of which has been controlled by the resurgence of the monte epomeo block the new data contribute to a clearer understanding of the long term volcanic and magmatic evolution of ischia

thermotectonic history of mt logan yukon territory canada implications of multiple episodes of middle to late cenozoic denudation abstract the extreme relief of the st elias mountains including mt logan is suggestive of a young mountain belt new apatite fission track data indicate that the mt logan massif experience rapid low temperature cooling during three distinct periods during the middle eocene middle miocene and pliocene each cooling episode the magnitude of which varies due to temporal variations in recorded paleogeothermal gradients can be tentatively linked to a tectonic cause eocene cooling may be due to re equilibration of isotherms following normal faulting caused by a combination of thermal weakening of the crust and a decrease in regional compressional stress due to the 43 ma change in relative motions between the pacific and north american plates the cause of miocene cooling is problematic and could reflect denudation in response to initial underplating of the yakutat terrane or a recorded change in heat flow unrelated to denudation pliocene cooling reflects erosion due to surface uplift that produced the spectacular present day topography of the st elias mountians this surface uplift is probably related to the coeval significant change in relative motion between the north american and pacific plates and or resistance to subduction by the yakutat terrane

cooling history of the st elias syntaxis southeast alaska revealed by geochronology and thermochronology of cobble sized glacial detritus

debris avalanche deposits associated with large igneous province volcanism an example from the mawson formation central allan hills antarctica an up to 180 m thick debris avalanche deposit related to ferrar large igneous province magmatism is observed at central allan hills antarctica this jurassic debris avalanche deposit forms the lower part member m 1 of the mawson formation and is overlain by thick volcaniclastic layers containing a mixture of basaltic and sedimentary debris member m 2 the m 1 deposit consists of a chaotic assemblage of breccia panels and megablocks up to 80 m across in contrast to m 2 it is composed essentially of sedimentary material derived from the underlying beacon supergroup the observed structures and textures suggest that the breccias in m 1 were mostly produced by progressive fragmentation of megablocks during transport but also to a lesser extent by disruption and ingestion of the substrate by the moving debris avalanche the upper surface of the debris avalanche deposit lacks large hummocks and sandstone breccias dominate volumetrically over megablocks within the deposits this indicates pervasive and relatively uniform fragmentation of the moving mass and probably reflects the weak and relatively homogenous nature of the material involved the avalanche flowed into a preexisting topographic depression carved into the beacon sequence and flow indicators reveal a northeastward movement the source area is probably now hidden under the antarctic ice sheet sparse basaltic bodies which were hot and plastic during transport in m 1 reveal the role of ferrar magmatism in triggering the avalanche possibly in relation to the emplacement of large subsurface intrusions the documented deposits indicate that debris avalanches are among the various phenomena that can accompany the early stages of large igneous province magmatism despite the common absence of large central volcanic edifices where large igneous provinces develop in association with faulting or slow preeruptive uplift accompanied by deep valley incision there is a high probability that feeder dikes will approach the surface in areas of steep topography allowing volcano seismicity and fluid overpressures associated with intrusion to effectively trigger avalanches

apatite u th he thermochronometry using a radiation damage accumulation and annealing model helium diffusion from apatite is a sensitive function of the volume fraction of radiation damage to the crystal a quantity that varies over the lifetime of the apatite using recently published laboratory data we develop and investigate a new kinetic model the radiation damage accumulation and annealing model rdaam that adopts the effective fission track density as a proxy for accumulated radiation damage this proxy incorporates creation of crystal damage proportional to production from u and th decay and the elimination of that damage governed by the kinetics of fission track annealing the rdaam is a version of the helium trapping model hetm shuster d l flowers r m and farley k a 2006 the influence of natural radiation damage on helium diffusion kinetics in apatite earth planet sci lett 249 148 161 calibrated by helium diffusion data in natural and partially annealed apatites the chief limitation of the hetm now addressed by rdaam is its use of he concentration as the radiation damage proxy for circumstances in which radiation damage and he are not accumulated and lost proportionately from the crystal by incorporating the rdaam into the hefty computer program we explore its implications for apatite u th he thermochronometry we show how u th he dates predicted from the model are sensitive to both effective u concentration eu and details of the temperature history the rdaam predicts an effective he closure temperature of 62 c for a 28 ppm eu apatite of 60 m radius that experienced a 10 c ma monotonic cooling rate this is 8 c lower than the 70 c effective closure temperature predicted using commonly assumed durango diffusion kinetics use of the rdaam is most important for accurate interpretation of u th he data for apatite suites that experienced moderate to slow monotonic cooling 1 0 1 c ma prolonged residence in the helium partial retention zone or a duration at temperatures appropriate for radiation damage accumulation followed by reheating and partial helium loss under common circumstances the rdaam predicts u th he dates that are older sometimes much older than corresponding fission track dates nonlinear positive correlations between apatite u th he date and eu in apatites subjected to the same temperature history are a diagnostic signature of the rdaam for many but not all thermal histories observed date eu correlations in four different localities can be explained with the rdaam using geologically reasonable thermal histories consistent with independent fission track datasets the existence of date eu correlations not only supports a radiation damage based kinetic model but can significantly limit the range of acceptable time temperature paths that account for the data in contrast these datasets are inexplicable using the durango diffusion model the rdaam helps reconcile enigmatic data in which apatite u th he dates are older than expected using the durango model when compared with thermal histories based on apatite fission track data or other geological constraints it also has the potential to explain at least some cases in which u th he dates are actually older than the corresponding fission track dates

control of lithospheric inheritance on neotectonic activity in northwestern canada lithospheric inheritance is thought to affect the location and reactivation of tectonic structures through successive cycles of supercontinent formation and dispersal however its relation to neotectonic activity remains unclear in northwestern canada abundant seismicity throughout the northern canadian cordillera ncc is geographically confined by several crustal scale boundaries yet its southern extent terminates abruptly along the inferred westward extension of a late cretaceous rifted margin boundary called the liard transfer zone ltz we use seismic data to show that the uppermost mantle beneath the cordillera exhibits a sharp north south contrast in fabric across the ltz south of the ltz fast axes of seismic wave propagation align closely with the lithospheric mantle fabric orientation of the adjacent canadian shield north of the ltz fast axes are reoriented subparallel to the motion of the pacific plate and follow the strike of the large dextral strike slip tintina and denali faults we attribute changes in anisotropic delay times across the tintina and denali faults to localized shear within the lithosphere this implies that the crust and lithospheric mantle remained mechanically coupled during shearing we propose that the contrast in uppermost mantle structure across the ltz reflects a change in the nature and origin of the lithospheric mantle from inherited rifted margin structures which affects the stability of the lithosphere and limits the extent of seismic activity within the ncc these results indicate that neotectonic activity in modern cordilleras is controlled in part by inherited upper mantle structures

response of groundwater chemical characteristics to ecological water conveyance in the lower reaches of the tarim river xinjiang china the purpose of this study was to determine the chemical characteristics of the groundwater and their changes in response to ecological water conveyance along a cut off river section in the lower reaches of the tarim river xinjiang china during the intermittent ecological water conveyance between 2000 and 2007 data were collected at 33 monitoring wells in nine sections in the lower reaches of the river the results show that the groundwater quality improved continuously with increasing numbers of ecological water conveyance episodes longitudinally the changing trend in groundwater salinity within the river reach was approximately w shaped the two peak values appeared in the tugmailai section in the middle and in the kaogan section in the lower part of the river reach transversely the changing trend in groundwater salinity showed obvious salt accumulation in the groundwater 750 m from the river channel the groundwater salinity within 750 m of the river channel was relatively low and it did not change greatly the groundwater salinity decreased along both sides of the river which favoured the restoration of the riparian vegetation these results also demonstrate a significant correlation between the height of the groundwater and groundwater salinity the groundwater salinity was relatively low and the vegetation cover was greater than 30 in areas of groundwater level of 4 5 m copyright c 2009 john wiley sons ltd

the structure of a hydrothermal system from an integrated geochemical geophysical and geological approach the ischia island case study the complexity of volcano hosted hydrothermal systems is such that thorough characterization requires extensive and interdisciplinary work we use here an integrated multidisciplinary approach combining geological investigations with hydrogeochemical and soil degassing prospecting and resistivity surveys to provide a comprehensive characterization of the shallow structure of the southwestern ischia s hydrothermal system we show that the investigated area is characterized by a structural setting that although very complex can be schematized in three sectors namely the extra caldera sector ecs caldera floor sector cfs and resurgent caldera sector rcs this contrasted structural setting governs fluid circulation geochemical prospecting shows in fact that the caldera floor sector a structural and topographic low is the area where co2 rich 40 cm3 l hydrothermally mature log mg na ratios 150 g m 2 d 1 is clearly captured by electrical resistivity tomography ert and transient electromagnetic tem surveys as a highly conductive resistivity 10 000 mg l and poorly conductive meteoric derived tds 4 000 mg l waters are observed respectively we finally integrate our observations to build a general model for fluid circulation in the shallowest 0 5 km part of ischia s hydrothermal system

palaeocene recent plate boundaries in the ne atlantic and the formation of the jan mayen microcontinent abstract breakup and sea floor spreading between greenland and eurasia established a series of new plate boundaries in the north atlantic region since the late palaeocene a conventional kinematic model from pre breakup to the present day assumes that eurasia and greenland moved apart as a two plate system however new regional geophysical datasets and quantitative kinematic parameters indicate that this system underwent several adjustments since its inception and suggest that additional short lived plate boundaries existed in the ne atlantic among the consequences of numerous plate boundary relocations is the formation of a highly extended or even fragmented jan mayen microcontinent and subsequent deformation of its margins and surrounding regions the major oligocene plate boundary reorganization and microcontinent formation might have been precluded by various ridge propagations and or short lived triple junctions ne and possibly sw of the jan mayen microcontinent from the inception of sea floor spreading 54 ma to c18 40 ma our model implies a series of failed ridges offshore the faeroe islands a northern propagation of the aegir ridge ne of the jan mayen microcontinent and a series of triple junctions and or propagators in the southern greenland basin

statistical trends in the intraplate stress field the world stress map wsm database contains thousands of intraplate stress indicators with the potential to provide important constraint for arguments about the relationship between tectonic stresses and both the kinematics and dynamics of plate motion previous studies which relied almost exclusively on visual inspection of the data established the existence of broad regions of uniform maximum horizontal compressive stress orientation shmax and stress regimes on a regional scale in the present study we present a statistical analysis of the wsm stress indicators with the aim of quantifying trends in both the shmax orientations and stress regimes the analysis was carried out within 5 5 bins which provide a resolution of several hundred kilometers only the 4537 high quality wsm indicators with rating of a to c were used in the analysis we present results for two types of analysis on the information contained within the bins first we evaluate the spatial distribution of the average stress regime normal strike slip or thrust second we apply the rayleigh test a standard statistical method in the analysis of directional data to the distribution of shmax orientations to test the null hypothesis that the orientations are random an important aspect of our study is the quantification of the conclusions drawn from visual inspection of the world stress map our results indicate that broad regions of uniform shmax orientations exist in most continental regions at high confidence levels 90 and 95 and are less robust in the slowest moving continental plates we also quantify the predominance of strike slip and compressional stress regimes in continental regions importantly our analysis provides information about trends in the shmax orientations in regions where large amounts of scatter in the directional data prevented conclusions being drawn from visual inspection of the data for example in western north america and continental australia furthermore we find a strong correlation between average shmax orientations and both the ridge push torque and the absolute plate velocity azimuths our observation that a greater number of shmax orientations correlate with the ridge push torque directions is further evidence that the intraplate stress field is strongly influenced by the ridge push force

the ischia debris avalanche first clear submarine evidence in the mediterranean of a volcanic island prehistorical collapse sector or flank collapse with related debris avalanches is increasingly recognized as a relatively common volcanic behaviour in particular for large hot spot related oceanic islands here we report the case of a catastrophic collapse that occurred at ischia volcanic island in prehistorical times and was driven by the volcano tectonic uplift of mt epomeo the major relief of the island the collapse left a subaerial to submarine horseshoe scar on the southern flank of the island and generated a debris avalanche incorporating thousands of giant blocks dispersed as far as 50 km from the island during the emplacement part of the debris avalanche evolved into a debris flow covering an area of 250 300 km2 this constitutes the first clear evidence of a submarine debris avalanche in the mediterranean sea the major collapse was followed and probably also preceded by recurrent less catastrophic terrestrial and underwater failures two other undersea hummocky deposits are found north and west of the island and might tentatively be correlated to the major southern collapse such volcanic behaviour previously unknown for ischia volcano has likely triggered tsunami waves over the entire bay of naples raising the question of their impact on prehistorical historical communities

slope instability induced by volcano tectonics as an additional source of hazard in active volcanic areas the case of ischia island italy ischia is an active volcanic island in the gulf of naples whose history has been dominated by a caldera forming eruption ca 55 ka and resurgence phenomena that have affected the caldera floor and generated a net uplift of about 900 m since 33 ka the results of new geomorphological stratigraphical and textural investigations of the products of gravitational movements triggered by volcano tectonic events have been combined with the information arising from a reinterpretation of historical chronicles on natural phenomena such as earthquakes ground deformation gravitational movements and volcanic eruptions the combined interpretation of all these data shows that gravitational movements coeval to volcanic activity and uplift events related to the long lasting resurgence have affected the highly fractured marginal portions of the most uplifted mt epomeo blocks such movements mostly occurring since 3 ka include debris avalanches large debris flows lahars smaller mass movements rock falls slumps debris and rock slides and small debris flows and deep seated gravitational slope deformation the occurrence of submarine deposits linked with subaerial deposits of the most voluminous mass movements clearly shows that the debris avalanches impacted on the sea the obtained results corroborate the hypothesis that the behaviour of the ischia volcano is based on an intimate interplay among magmatism resurgence dynamics fault generation seismicity slope oversteepening and instability and eruptions they also highlight that volcano tectonically triggered mass movements are a potentially hazardous phenomena that have to be taken into account in any attempt to assess volcanic and related hazards at ischia furthermore the largest mass movements could also flow into the sea generating tsunami waves that could impact on the island s coast as well as on the neighbouring and densely inhabited coast of the neapolitan area

the structure of mountain fronts commonly the part of a mountain front which is visible at the surface consists of foreland dipping thrust belt rocks elevated above their regional structural position and overlain more or less conformably by molasse several explanations for their geometry are possible 1 major detachments exist within or beneath the molasse resulting in transport of the foreland basin examples of this geometry come from the swiss molasse plain the southern pyrenees and the mackenzie mountains of canada 2 displacement is lost on major backthrusts beneath the frontal monocline examples cited here are the rockies of alberta the sulaiman ranges of pakistan the mackenzies and the andes in peru 3 thrust sheets travelled over an old land surface and syntectonic molasse contemporaneously offlaps the topographic high of the thrust front this phenomenon occurs along the alpine thrust front in haute provence 4 the frontal fold represents deformation above a large scale thrust tip no unequivocal example of tip line strain at this scale has been recorded although this type of deformation may occur in the brooks range of alaska in many areas mountain fronts show a combination of these idealized geometries

a revised crustal stress orientation database for canada abstract the canadian database on contemporary crustal stress has not been revised systematically in the past two decades here we present the results of our new compilation that contains 514 new data records for the orientation data of maximum compressive horizontal stress and 188 data records that were re assessed in total the canadian stress database has now 1667 data records which is an increase of about 45 from these data a new canadian stress map as well as one for the province of alberta is presented to analyse the stress pattern we use the quasi median on the circle as a smoothing algorithm that generates a smoothed stress map of the maximum compressive horizontal stress orientation on a regular grid the newly introduced quasi interquartile range on the circle estimates the spreading of the data and is used as a measure for the wave length of the stress pattern the result of the hybrid wavelength analysis confirms that long spatial wavelength stress patterns 1000 km exist in large areas in canada the observed stress pattern is transmitted through the intra plate regions the results reveal that shorter spatial wave length variation of the maximum compressive horizontal stress orientation of less than 200 km prevails particularly in south eastern and western canada regional stress sources such as density contrasts active fault systems crustal structures etc might have a significant impact in these regions in contrast to these variations the observed stress pattern in the alberta basin is very homogeneous and mainly controlled by plate boundary forces and body forces the influence of curvature of the rocky mountains salient in southern alberta is minimal the present day horizontal stress orientations determined herein have important implications for the production of hydrocarbons and geothermal energy in the alberta basin

seasonal and spatial variation in groundwater quality along the hillslope of an agricultural research catchment western france shallow groundwater that develops on hillslopes is the main compartment in headwater catchments for flow and solute transport to rivers although spatial and temporal variations in its chemical composition are reported in the literature there is no coherent description of the way these variations are organized nor is there an accepted conceptual model for the mechanism involved on the basis of the results from an experimental hillslope we propose a description of the variation in spatial and temporal patterns of groundwater chemical composition and discuss the mechanisms involved we instrumented a headwater catchment with a network of 42 nested piezometers along a 200 m hillslope and monitored major anion composition frequently over a 2 year period the results demonstrated that i the anionic composition in water table fluctuation zone varied significantly compared to deeper portions of the aquifer on the hillslope confirming that this layer constitutes a main compartment for the mixing of new recharge water and old groundwater ii deeper parts of the aquifer exhibited seasonal variations with structured hysteretic patterns suggesting that mixing processes also occurred at greater depths and iii these hysteretic patterns were dampered from upslope to downslope indicating an increased influence of lateral flow downslope we recommend that the generality of these observations be assessed in different environments as they can constitute a new set of processes to include in hydrological models copyright 2010 john wiley sons ltd

the interaction between regional and local tectonics during resurgent doming the case of the island of ischia italy abstract the volcanic island of ischia is located on the tyrrhenian margin of central italy characterized by plio quaternary nw se and ne sw trending extensional fractures ischia displays a resurgent dome uplifted by at least 800 m in the last 33 ka remote sensing and field data have been collected to study the structural setting of the island the deformation pattern associated with resurgence and the superimposition of the regional and the resurgence induced stress fields nw se and ne sw extensional fracture systems predominate throughout the island and around the resurgent block suggesting a relationship with the regional extensional structures these systems were formed before resurgence and were partly reactivated during resurgence the reactivation of pre existing regional systems during resurgence confined the extent of the uplifted area n s and e w trending systems have been found exclusively at the borders of the dome and are interpreted as being induced by resurgence the topmost resurgent block shows an octagonal shape in map view and is tilted at an angle of 15 around a ne sw trending horizontal axis the block is partly bordered by high angle inward dipping regional faults more than 90 in volume of the volcanic products coeval with resurgence on ischia have been erupted outside the resurgent block area suggesting that the resurgence process locally replaced volcanic activity in the last 33 ka

14c geochronological constraints for the volcanic history of the island of ischia italy over the last 5000 years abstract the chronology of the most significant eruptions at the island of ischia in the last 5000 years has been studied by means of accelerator mass spectrometry to obtain 14 c data the results are in good agreement with stratigraphical and archeological constraints this allows interpretation of the measured dates as ages of the eruptions which produced the deposits overlying or incorporating the sampled paleosols and charcoal fragments respectively these ages define the timing of volcanism in the last 5000 years suggesting that the recent volcanic activity at ischia is characterized by periods of very intense volcanism alternating to periods of quiescence this timing of the volcanism is correlated with the behaviour of the magmatic system and dynamics of resurgence of the mt epomeo block

the influence of natural radiation damage on helium diffusion kinetics in apatite abstract stepwise degassing diffusion experiments on 39 different apatite samples using radiogenic 4he and proton induced 3he reveal a range in closure temperature tc from 50 to 115 c for a cooling rate of 10 c myr there is no correlation between helium diffusion and apatite chemistry including f cl ratio but the closure temperature is positively correlated with the radiogenic 4he concentration 4he in each sample we argue that 4he is a proxy for a sample s natural exposure to actinide radioactivity below the closure temperature and that helium diffusion in apatite is impeded by radiation induced damage to the apatite structure the kinetics must therefore be an evolving function of time measured diffusivities thus reflect a snapshot in time and cannot alone be applied to the thermochronometric interpretation of a given sample the effect of radiation damage on helium diffusion appears to far exceed other known controls on helium diffusivity including grain size our diffusion data are well described by a previously proposed quantitative model that consists of two arrhenius relations one for volume diffusion through undamaged mineral structure and one for release of helium from radiation damage traps the unknown parameters in this trapping model were determined from the diffusion experiments and allow us to develop a tentative mathematical function that relates diffusivity to temperature and 4he by inserting this function into a 4he production diffusion model we have explored how these results affect the interpretation of apatite u th he thermochronometry the model predicts that the effective 4he closure temperature of apatite will vary with cooling rate and effective u concentration eu and may differ from the commonly assumed tc of 70 c by up to 15 c the 4he partial retention zone will look similar to previous expectations but its depth will depend on accumulation time and on eu most notably samples subjected to reheating after accumulation of substantial radiation damage will be more retentive than previously expected these predictions are consistent with recent observations of unexpected apatite u th he ages in some settings

role of an impermeable layer in controlling groundwater chemistry in a basaltic aquifer beneath an agricultural field jeju island south korea abstract hydrochemical data major cations and anions and trace metals such as fe mn and v of groundwater n 144 were collected from 15 pre existing wells in the gosan area along the southwestern coast of jeju island south korea between january and october 2010 these were used to investigate the spatio temporal variability of groundwater quality in a basaltic aquifer beneath an agricultural field in the western part of the study area an impermeable clay rich layer gosan formation overlies the basaltic aquifer prohibiting direct recharge from rainwater infiltration and allowing a shallow perched aquifer to form above the formation robust principal component analysis robpca was performed to investigate the hydrochemical characteristics twenty seven outlying samples were separated from the total dataset among these 17 samples reflected seawater effects and seven samples reflected abnormally high impacts from agricultural contamination for the rest regular observations n 117 and a good leverage point robpca showed that principal component pc 1 effectively distinguishes uncontaminated water from those samples reflecting agricultural contamination variables with positive pc 1 loadings tds ca mg no 3 so 4 and cl indicate agricultural contamination while negative pc 1 loadings ph na k hco 3 and v possibly indicate basalt weathering samples with chemistry controlled by agricultural contamination are restricted to the eastern part of the study area while uncontaminated water is predominantly observed in the western part where the gosan formation occurs such a distinct spatial pattern indicates that overall groundwater quality is regulated by the occurrence of the impermeable formation groundwater samples from wells near the edge of the gosan formation show seasonal fluctuations in water quality with factor scores that indicates uncontaminated water in the dry season january to april and agricultural contamination in the wet season may to october this suggests that groundwater below the marginal part of the impermeable layer is seasonally contaminated by a temporal extension of the pollution front during the wet season even though the impermeable layer plays a role as a natural barrier to protect groundwater from the infiltration of surface contaminants this study also shows the advantage of robpca to successfully identify spatio temporal variation of groundwater quality in an area where diverse hydrochemical processes are coexisting and anormalous samples occur

modeling unsaturated flow and transport in the saprolite of fractured sedimentary rocks effects of periodic wetting and drying 1 whereas a number of unsaturated zone modeling studies have been conducted on dual porosity systems where the matrix has low permeability few have been conducted on systems where the matrix has relatively high permeability in humid climates in situ weathering of bedrock can form saprolite saprolite usually has high matrix porosity and variable permeability that is a reservoir for solute storage and can have relict fractures that transport solute rapidly on the basis of a field investigation where natural chemical tracers were monitored at high resolution during storm events a numerical model was created that simulated variably saturated transport in the saprolite a series of simulations were performed to explore solute transport during cycles of wetting and drying modeling results indicated that the advective flux of solutes from the fractures into the matrix during wetting was greater than from the matrix back into the fractures during drying resulting in a net storage of solutes in the matrix we hypothesize that the amount of net solute storage in the matrix may increase as the frequency of wetting drying cycles increases up to an optimum frequency at frequencies higher than the optimum the amount of solute storage in the matrix may decrease because the system behaves more like a fully saturated system where diffusion is the dominant transport process between fractures and matrix these conclusions have significant implications for such processes as remedial strategies for contaminants in the unsaturated zone the application of fertilizers and quantification of mineral weathering and dissolution rates

seismically induced landslide susceptibility evaluation application of a new procedure to the island of ischia campania region southern italy in this paper we present an approach for evaluating landslide susceptibility in seismic areas it is known that earthquake induced landslide susceptibility is related to several often interplaying factors nevertheless an effective grade 2 zonation should be characterized by a good balance between simplicity quickness and reliability the gis based procedure we present employs only three factors that we believe are the most significant in this susceptibility assessment the type of outcropping rocks soils the slope angle and the mcs intensity the local annual precipitation certainly an essential factor is considered here as a parameter whose seasonal pattern is constant in time and space each of the three parameters is expressed as a significance percentage and the resulting seismic landslide susceptibility level of an area is given by the average of the significances of the first two factors multiplied by the significance of the third factor the procedure was set and tested on the volcanic island of ischia southern italy which was affected by several historical earthquake induced landslides the results of this susceptibility zonation test at ischia show a very good match between the distribution of the sources of historical landslides and the areas we identified as the most susceptible ones

morphological and geochemical evidence of neotectonics in the volcanic area of monti vulsini latium italy interdisciplinary research has been carried out to contribute to the definition of the neotectonic arrangement of the eastern area of monti vulsini affected by upper pleistocene volcanic activity particularly geochemical and geomorphological inquiries have been performed to identify tectonic elements whose recent activity could be related to the volcanic history of this area the morphological field evidence of tectonics as well as the analysis of azimuthal distribution of stream channels and the statistical analysis of the amplitude of relief ar revealed the eastern monti vulsini volcanic area to be controlled by different tectonic alignments at the same time the geochemical contribution focused on geostatistical elaboration of soil gas data has attempted to process unbiased criteria to define soil gas anomalies and to infer correlation with their fault related linear geometry in particular rose diagrams of anomalous gas concentration alignments and azimuthal distribution of stream channels performed for each hierarchical order were compared to obtain information about the location and orientation of tectonic elements as well as about the possible reconstruction of their activity in recent times by means of relative chronology