hillslope drainage with sudden drawdown closed form solution and laboratory experiments theory is developed for hillslope drainage and is applied to the condition of sudden drawdown at the aquifer outlet the equations for prediction of cumulative outflow volume flow rate and water table profile are based on the boussinesq approximation for subsurface water flow above a sloping impermeable layer the advantages of the theory presented here are that the assumption of a long thin aquifer is unnecessary the same equations apply to both sloping and horizontal aquifers and the equations contain only parameters that are easily measured or estimated slope drainable porosity saturated hydraulic conductivity and layer thickness the accuracy of the outflow equations is illustrated by a series of laboratory experiments

early stage sinkhole formation in the acque albule basin of central italy from geophysical and geochemical observations abstract sinkhole occurrence along the tyrrhenian margin of the central apennines is of great importance for applied research land management and civil protection this study reports on gps altimetry magnetic gravity geoelectric seismic and soil gas measurements of a rapidly developing sinkhole near the guidonia military airport the measurements revealed an elliptical 2 m depression elongated 220 m in the nne ssw direction with the minor axis of 110 m in the spring of 2013 two vertical cavities formed in the eastern and northeastern flanks of the depression whose depths and shapes are rapidly evolving with the formation of widespread fracturing along the same side the geophysical observations image the developing sinkhole to a depth of some 50 m the presence of the travertino lithotype around the depression down to at least 40 m and the lack of this lithotype below the lowered area the sinkhole s evolution appears to be structurally controlled by local and regional faulting these results are useful for designing further geophysical geotechnical and geochemical studies to monitor the sinkhole s evolution and to assess the hazard it presents in densely urbanized area

the structural state of the former lower continental crust in calabria s italy in the northern serre s italy a continuous section through a former lower continental crust is exposed schenk 1984 1985 these granulite facies rocks have not been penetratively deformed during their uplift to higher crustal levels therefore they allow to study the structural state of the lower continental crust most rockforming minerals among them ortho and clinopyroxene and cordierite show recrystallization structures quarz basal subgrain boundaries are developed in lower levels of the lower crust and disappear toward higher levels in addition to dimensional orientations of the rockforming minerals the preferred crystallographic orientations of plagioclases cordierite amphibole pyroxenes and rarely quartz reflect the strain orientation of the prograde high t deformation during this deformation the stretching direction was constant nne ssw throughout the exposed lower crustal section shear indicators are rare this points to the fact that deformation has been homogeneous and coaxial flattening there is only a small variation in orientation and strength of textures throughout the exposed lower crust therefore neighbouring layers of different composition rather than different deformation might serve as seismic reflectors in the former lower crust

shear wave anisotropy of laminated lower crust beneath urach sw germany a comparison with xenoliths and with exposed lower crustal sections in order to investigate the laminated lower crust beneath urach sw germany we analysed 1 the anisotropy and reflectivity of seismic shear waves and 2 the composition of xenoliths samples we conclude that the directional dependence of shear waves of the lower crust is effectively transversely isotropic with a maximum velocity difference of 3 to 6 both seismic signature and petrological information are compared with reference profiles deduced from the exposed lower crustal sections of ivrea and calabria italy the comparison based on synthetic seismograms shows that the observed combination of shear wave anisotropy and reflectivity pattern corresponds to alternating layers containing a high amount of metapelites such as found in the calabria profile and in the val strona subsection of ivrea the main portion of the whole rock anisotropy is caused by the lattice preferred orientation of anisotropic minerals so called intrinsic anisotropy the effect of alternating rock layering so called layering anisotropy contributes only a minor portion to the whole rock anisotropy layered mafic intrusions such as found in the val sesia subsection of ivrea are nearly isotropic both seismic anisotropy and xenoliths indicate that mafic layers do not play a major role for the laminated lower crust at urach they may be restricted to a thin layer at the crust mantle boundary

ascent velocity and dynamics of the fiumicino mud eruption rome italy author s vona a giordano g de benedetti aa d ambrosio r romano c manga m abstract 2015 american geophysical union all rights reserved in august 2013 drilling triggered the eruption of mud near the international airport of fiumicino rome italy we monitored the evolution of the eruption and collected samples for laboratory characterization of physicochemical and rheological properties over time muds show a progressive dilution with water the rheology is typical of pseudoplastic fluids with a small yield stress that decreases as mud density decreases the eruption while not naturally triggered shares several similarities with natural mud volcanoes including mud componentry grain size distribution gas discharge and mud rheology we use the size of large ballistic fragments ejected from the vent along with mud rheology to compute a minimum ascent velocity of the mud computed values are consistent with in situ measurements of gas phase velocities confirming that the stratigraphic record of mud eruptions can be quantitatively used to infer eruption history and ascent rates and hence to assess or reassess mud eruption hazards

conditions for long lasting gas eruptions the 2013 event at fiumicino international airport rome italy abstract a hazardous gas eruption from two very close shallow boreholes occurred near the fiumicino international airport of roma italy from august to december 2013 the erupted gas was mostly co 2 of deep origin and gas output was high and sustained over time reaching values of nearly 20 t day 1 after 3 months the gas flux was still above 5 t day 1 and was only stopped in december 2013 by long and expensive works of closure of the boreholes the gas eruption was uncommon as being associated with the building of two mud volcanoes this style of sustained deep co 2 eruptions contrasts with the more common short lived eruptions of shallow biogenic methane dominated gas pockets in this work we present the chronology of the event the results of geological geochemical and geophysical monitoring and a numerical modeling we propose that the august december 2013 sustained and prolonged event does not relate to the simple degassing of a shallow isolated pocket of gas on the contrary it reflects very specific conditions in a shallow reservoir hosted in a 10 m thick gravel layer at 40 m within the tiber river delta deposits related to the interplay between the total pressure and the fraction of free co 2 initially present across very narrow value ranges around 0 59 mpa and 0 18 respectively the coexistence of short lived and long lived eruptions from the same reservoir suggest that these conditions are not achieved everywhere in the gas reservoir despite its homogeneous properties this consideration implies either a pressure compartmentalization of the reservoir or the occurrence of a transient possibly associated with an impulsive release of gas from greater depths the involvement of deeper and larger gas reservoirs connected along faults is evidenced by geophysical investigations this conceptual model bears significant implications for gas hazard studies

velocity anisotropy and shear wave splitting in rocks from the mylonite belt along the insubric line ivrea zone italy velocity anisotropy and shear wave splitting has been measured up to 600 mpa on seventeen mylonitic samples from the mylonite belt along the insubric line the rocks which range from felsic to mafic in composition have experienced large ductile strain seismic anisotropy a and shear wave splitting delta vs is significantly pressure dependent velocity anisotropies of p and s waves range from 9 to 27 vp and 10 to 25 vs at 10 mpa and from 4 to 15 and 6 to 17 at 600 mpa respectively oriented microcracks in addition to preferred orientation of anisotropic rock forming minerals contribute largely to velocity anisotropy and shear wave splitting in the low pressure range at high pressure 600 mpa where most of the cracks are closed velocity anisotropy and shear wave splitting is dominated by preferred mineral orientation texture the experimental data at 600 mpa are in fairly good agreement with velocity calculations voigt averages based on volume percentages of major minerals the stiffness tensor of respective rock forming minerals and the measured crystallographic orientation texture related reflection coefficients rc at the protolith mylonite interfaces normal incidence no density change are 0 04 vp and 0 03 vs for extremely anisotropic mylonites a approximate 12 calculations of the variation of reflection coefficients due to velocity anisotropy of p waves in mylonites of different lithologies literature data included give 90 less than 0 1 66 less than 0 05 and 44 less than 0 03 these results suggest that the directional variation of wave velocities in anisotropic mylonites alone does not provide the impedance contrast necessary to give rise for strong seismic reflections

sediment hosted geothermal systems review and first global mapping abstract sediment hosted geothermal systems shgss are hybrid geological systems where volcanic and sedimentary domains interact leading to mixtures of inorganic and organic gases typically characterized by geothermal thermometamorphic or mantle derived co2 and biotic microbial or thermogenic ch4 shgss occur in sedimentary basins crossed by magmatic intrusions or involved in volcanic plumbing systems these systems can be of considerable interest for petroleum exploration and natural greenhouse gas emission studies but systematic studies for their characterization and worldwide distribution are missing here we provide a review of shgss identified so far and propose methodological criteria for their definition and identification based on integrated geological and gas geochemical parameters we find that shgss are typically characterized by a fluids dominated by mantle or decarbonation methamorphic co2 50 vol b considerable amounts of ch4 and heavier hydrocarbons at least 1 5 vol generally up to 30 40 vol produced by microbial or thermogenic degradation of organic matter hosted in sedimentary rocks c tectonically active sedimentary basins back arc rift zones and foredeep generally hosting petroleum fields and within 300 km from recent or ancient volcanic centers this analysis resulted in a global map including a first set of 33 shgss located in north america central and eastern europe far east eastern oceania and northern new zealand and a second set of potential shgs prone areas occurring also in south america north africa middle east and kamchatka the present shgs map can evolve on the basis of more detailed geological analysis and new gas geochemical data

analytical solutions to hillslope subsurface storm flow and saturation overland flow we present the analytical solutions to a hillslope based formulation of subsurface storm flow and saturation overland flow here a hillslope is defined as the area between two streamlines originating from two ends of a channel link or from the channel head and ending at the ridgelines the three dimensional soil mantle of a hillslope is reduced to a one dimensional profile along which the soil moisture and discharge are modeled continuity and a kinematic form of darcy s law lead to quasi linear wave equations solvable with the method of characteristics examples are given to illustrate the ability and limitations of the solutions in capturing the essential runoff behavior of different slope types

post caldera activity in the alban hills volcanic district italy 40ar 39ar geochronology and insights into magma evolution we present 24 40ar 39ar ages for the youngest volcanic products from the alban hills volcanic district rome combined with petrological data on these products we have attempted to define the chronology of the most recent phase of activity and to investigate the magma evolution of this volcanic district the early mainly explosive activity of the alban hills spanned the interval from 561 1 to 351 3 ka after approximately 50 kyr of dormancy a mainly effusive phase of activity took place accompanied by the strombolian activity of a small central edifice monte delle faete this second phase of activity spanned the interval 308 2 to 250 1 ka after another dormancy period of approximately 50 kyr a new hydromagmatic phase of activity started at 200 ka at several centers located to the southwest of the monte delle faete edifice after an initial recurrence period of approximately 50 kyr which also characterized this new phase of activity the longest dormancy period approximately 80 kyr in the history of the volcanic district preceded the start of the activity of the albano and giuturna centers at 70 1 ka results of our study suggest a quasi continuous magmatic activity feeding hydromagmatic centers with a new acme of volcanism since around 70 ka based on data presented in this paper we argue that the alban hills should not be considered an extinct volcanic district and a detailed re assessment of the volcanic hazard for the area of rome is in order

the dynamics of back arc extension an experimental approach to the opening of the tyrrhenian sea the e w opening tyrrhenian sea developed after the cretaceous palaeogene alpine collision nearly perpendicular to the motion of the african plate as a back arc of the adria ionian westward subduction three driving mechanisms have been proposed to explain the dynamic evolution of the tyrrhenian apennine system 1 the northward indentation of the african plate 2 the retreating subduction of the adria ionian lithosphere and 3 the gravitational collapse of the alpine post collisional wedge in order to define the relative contribution of each of these mechanisms in the neogene dynamic of the tyrrhenian apennine system we performed 3 d laboratory experiments in which we simulated a retreating subduction process in a compressional regime oriented perpendicularly to the direction of subduction in this framework we also tested the influence of the gravitational collapse of the overriding plate experiments were constructed using dry sand and silicone putties to simulate brittle upper crust and ductile lower crust upper mantle respectively these layers floated on a high density low viscosity glucose syrup which simulated the asthenosphere the main conclusion of our experiments is that large scale continental extension similar to that observed in the tyrrhenian area could be reproduced perpendicular to the shortening direction induced by the indentation of the african plate in this framework extensional processes are indeed possible if the trench retreat velocity is higher than the rate of shortening induced by the advancing african plate our experimental results indicate that this high trench retreat velocity could be explained by the coexistence of the gravitational collapse of the post alpine wedge with a slab pull process linked to the retreating subduction of the adria ionian plate while the first mechanism is predominant in the northern tyrrhenian area the second one seems to be important in the latest stage of extension and oceanic accretion of the southern tyrrhenian area

compaction creep of simulated anhydrite fault gouge by pressure solution theory v experiments and implications for fault sealing the sealing and healing behaviour of faults filled with anhydrite gouge by processes such as pressure solution is of interest in relation both to the integrity of faults cutting geological storage systems sealed by anhydrite caprocks and to seismic events that may nucleate in anhydrite bearing sequences such as those present in the seismogenic zone beneath the apennines we have developed a detailed series of kinetic models for pressure solution in anhydrite fault gouge allowing for dissolution diffusion and precipitation control to estimate the time scale on which such sealing and healing effects occur we compare the models obtained with previously reported experimental data on compaction creep rates in simulated anhydrite fault gouge tested under wet upper crustal conditions the results confirm earlier indications that compaction under these conditions likely occurs by diffusion controlled pressure solution applying our most rigorous model for diffusion controlled pressure solution constrained by the fit to the experimental data we infer that anhydrite fault sealing will occur in a few decades at most which is rapid compared with both co2 storage time scales and with the recurrence interval for seismicity in the apennines

strike slip faulting and block rotation a possible triggering mechanism for lava flows in the alban hills abstract it is suggested in this paper that two distinct tectonic triggers tapping different depths of a magma reservoir may be the cause of nearly contemporaneous eruptions of lava flows and ignimbrites in the alban hills the area between the alban hills and rome underwent alternating regional extensional and strike slip faulting during the middle pleistocene the geometries of the main structural dislocations in quaternary strata combined with a statistical analysis of drainage network trends show a structural pattern that is consistent with local strain partitioning in transpressive zones at strike slip fault bends superimposed on regional extension based on this analysis it is suggested that local clockwise block rotation between parallel n s strike slip faults might have generated local crustal decompression allowing relatively volatile free magma to rise from deep reservoirs beneath the alban hills triggering peripheral fissure lava flows in contrast the main ignimbrite eruptions appear to tap shallow volatile rich magma reservoirs and are controlled by extensional processes

shear wave anisotropy of laminated lower crust at the urach geothermal anomaly abstract deep seismic reflection studies have shown that lamellae are a widespread reflectivity pattern of the lower crust of the central european variscan belt this pattern has been interpreted inter alia as alternating subhorizontal layering of mafic and felsic rocks implying a tectonic process of structural and textural ordering consequently laminated lower crust should be elastically anisotropic the specific type of anisotropy should provide some insight into the mineral composition and the preferred orientation of minerals in the lower crust we have investigated this problem in the area of the urach geothermal anomaly south germany where a classical example of lower crust lamellae is found a restricted range of subsurface points was probed in a controlled source expanding spread seismic experiment with two orthogonal azimuths of observation up to 90 km source geophone offset both p and s waves were recorded with 3 component geophones at 80 140 m geophone spacing based on polarization analysis and traveltime interpretation the following results were obtained 1 s wave splitting is observed only for sms arrivals not for shallower reflections implying that the lower crust is anisotropic 2 the type of anisotropy is quasihexagonal transversely isotropic implying that there is no preferred mineral orientation within the horizontal plane 3 the coefficient of s wave anisotropy v max v min v min is estimated at 6 13 for sv type waves the sh wave velocity shows only small variation with offset 4 the observed relation between direction and velocity of s wave propagation can be explained by mafic rocks containing a high amount of orthopyroxene minerals horizontally aligned in the pure shear stress regime

seismic properties of rocks from an exposure of extended continental crust new laboratory measurements from the ivrea zone abstract compressional wave velocities for new samples from the ivrea verbano zone ivz and strona ceneri zone scz have been measured to 600 mpa in order to better understand the petrologic controls on velocity and to provide an expanded base for seismological models of the crust as represented by these terrains these data coupled with previous measurements show that preferred orientation of mica controls both the velocity hysteresis with pressure and seismic anisotropy of scz and ivz schists and gneisses ivz paragneisses form the basis of a linear velocity density relationship for metagraywackes of various metamorphic grade this relationship falls close to that expected for mafic rocks and overlaps velocity density data for ivz mafic gneisses one dimensional near vertical reflection models based on these data and recent structural reconstructions of the terrain show that lower crustal reflectivity can be related to high reflection coefficients associated with interlayered sequences of upper amphibolite granulite facies paragneiss mafic gneiss and ultramafic rocks transparent upper crustal levels in the model result from the overall similarity of velocities for schists gneisses and granites from the structurally and lithologically complex scz a mean lower crustal velocity of 7 1 km s is calculated for the part of the ivz composed of interlayered mafic gneiss and paragneiss and for another area dominated by a mafic layered igneous complex the velocity density analysis coupled with this observation emphasize the ambiguity inherent in interpretation of crustal composition from p wave velocity data in the absence of other constraints

seismicity seismogenic structures and crustal stress fields in the greater rome area central italy 1 instrumental seismicity of the greater rome area is analyzed using the most recent seismological database the aim of this study is to identify potential seismogenic structures responsible for the moderate seismicity that characterizes this sector where no surface faulting is expected on the basis of the absence of strong local earthquakes as evidenced by the 2000 year long historical record nevertheless in light of the great value and the high vulnerability of the architectural and monumental patrimony of rome even the occurrence of moderate events imposes a careful assessment of the hazard linked to the presence of active faults that are undetectable by means of classic geological field investigation seismic data here analyzed belong to the period 1997 2008 and show local magnitude ml ranging from 1 5 to 4 7 to better constrain the hypocentral depths we computed the vp vs ratio using a modified wadati method and the minimum 1 d velocity model that approximates the seismic structure of the study area moreover we applied a double difference hypocentral determination technique to improve earthquake locations most of the located seismicity appears to be concentrated within seven main clusters spatial distribution of the seismicity allowed us to identify several seismogenic structures corresponding to previously undetected or only supposed active faults the stress tensor obtained by inverting the focal mechanisms computed in this study is in agreement with the ne sw extensional tectonic stress active in the inner chain of the apennines although there is evidence of some local stress field heterogeneities

fine grained volcanic hydrothermal sedimentary rocks in permian lucaogou formation santanghu basin nw china implications on hydrocarbon source rocks and accumulation in lacustrine rift basins abstract subaqueous volcanic hydrothermal field is a complex hybrid geological system where sediments originated from volcanic hydrothermal lacustrine terrestrial and biotic sources are mixed recent petrological studies on such sediments have indicated a potential relationship between volcanic hydrothermal activities and oil generation and accumulation here we explore the mechanisms of sedimentation and oil accumulation in well laminated organic rich fine grained sedimentary rocks in permian lucaogou formation deposited in the lacustrine santanghu rift basin nw china we conducted petrographic carbon and oxygen isotopic and organic geochemical analyses of fifty four core samples from three wells forty eight samples from well w1 two from w2 four from w3 designed for tight oil exploration four main observations and interpretations are 1 the fine grained sediments are a mixture of volcanic hydrothermal detrital feldspar grains authigenic quartz crystals and primary lacustrine dolomite forming interbedded tuffaceous shale and dolostone 2 authigenic quartz crystals were precipitated from acidic hydrothermal fluids whereas fine grained angular alkaline feldspars were derived from subaqueous volcanic eruption 3 the toc content and oil generation potential increase with increased mixing of feldspars and carbonate minerals hence the dolomite bearing tuffaceous shale and tuffaceous dolostone are the best source rocks and 4 the fine grained sedimentary rocks are interpreted as a subaqueous volcanic hydrothermal deposit that controls the source potential the sedimentary processes of an ancient sediment hosted geothermal system and its implications on hydrocarbon source rocks and accumulation were first identified algal bloom induced by subaqueous eruptions is the main cause for episodic deposition of organic matter and extreme heterogeneity in both lithofacies and source rock distribution the results suggest that cone shaped buildups on seismic sections which were formed by volcanic hydrothermal deposits and contain highly mixed feldspar and carbonate sediments are the best hydrocarbon reservoirs and demonstrate a strong relationship between volcanic hydrothermal activities and hydrocarbon accumulation in an extensional tectonic setting

tiber delta co2 ch4 degassing a possible hybrid tectonically active sediment hosted geothermal system near rome fiumicino town in the tiber river delta near rome international airport italy is historically affected by large amounts of carbon dioxide co2 in the ground and gas eruptions triggered by shallow drilling while it is known that co2 originates from carbonate thermometamorphism and or mantle degassing the origin of methane ch4 associated with co2 is uncertain and the outgassing spatial distribution is unknown combining isotope gas geochemistry soil gas and structural stratigraphic analyses we provide evidence for a hybrid fluid source system classifiable as sediment hosted geothermal system shgs where biotic ch4 from sedimentary rocks is carried by deep geothermic co2 through active segments of a half graben molecular and isotopic composition of ch4 and concentration of heavier alkanes ethane and propane obtained from gas vents and soil gas throughout the delta area reveal that thermogenic ch4 up to 3 7 vol in soil gas 13cch4 37 to 40 vpdb vienna peedee belemnite and 2hch4 162 to 203 vsmow vienna standard mean ocean water in gas vents prevails over possible microbial and abiotic components the hydrocarbons likely result from known meso cenozoic petroleum systems of the latium tyrrhenian coast overmaturation of source rocks or molecular fractionation induced by gas migration are likely responsible for increased c1 c2 ratios co2 and ch4 soil gas anomalies are scattered along nw se and w e alignments which based on borehole geomorphologic and structural stratigraphic analyses coincide with active faults of a half graben that seems to have controlled the recent evolution of the tiber delta this shgs can be a source of considerable greenhouse gas emissions to the atmosphere and hazards for humans and buildings

carbon dioxide degassing from the albani hills volcanic region central italy the albani hills are affected by strong co2 degassing processes the amount of co2 which rises from the depths and subsequently dissolves into shallow groundwater has been estimated to be more than 4 2 109 mol year 1 most of the gas is released in localised anomalous spots lavinio solforata and ciampino albano nemi areas generated by fluid leakage processes from buried pressurized reservoirs hosted by structural highs of the calcareous siliceous marly basement the groundwater circulating in the anomalous areas becomes co2 oversaturated generating observable gas manifestations whose composition is mainly controlled by gas liquid separation processes a gas flow rate of 6 1 108 mol year 1 has been measured from the two larger manifestations using the accumulation chamber technique the presence at shallow level of co2 oversaturated groundwater can explain several episodes of sudden release of gas which was documented by historical chronicles from roman times until now

analytical approximation for the recession of a sloping aquifer an approximation is obtained for the recession of a sloping aquifer the analytical approximation can provide a useful tool to analyze data and obtain physical properties of the aquifer in contrast to the case of a horizontal aquifer when plotting the time derivative of the flux versus the flux on a log scale the result shows that the flux derivative reaches a minimum value and that the curve can have a slope of unity as often observed illustration of the application of the analytical results to the mahantango creek data is also discussed

terrestrial methane seeps and mud volcanoes a global perspective of gas origin abstract a global database of gas composition and methane stable isotopes of 143 terrestrial mud volcanoes from 12 countries and 60 seeps independent from mud volcanism from eight countries was compiled and examined in order to provide the first worldwide statistics on the origin of methane seeping at the earth s surface sixteen seep data were coupled with their associated subsurface reservoirs the surface seepage data indicate that at least 76 of the mud volcanoes release thermogenic gas with only 4 biogenic and 20 with mixed character the average 201 data of methane concentration and methane carbon isotope ratios 13 c 1 of mud volcanoes are 90 v v and 46 4 respectively the other types of seeps which are independent from mud volcanism have an average 13 c 1 value that is slightly higher 42 9 gases from mud volcanoes are generally lighter more methane less ethane and propane than their associated reservoir gases suggesting a molecular fractionation during advective fluid migration other types of seeps especially dry seeps maintain the reservoir c 1 c 2 c 3 bernard ratio mud volcanoes behave like a natural refinery and the origin of gas more isotopically enriched than 50 and with c 1 c 2 c 3 500 should be attributed to a thermogenic source rather than partial oxidation of biogenic gas some data that appear biogenic in the bernard diagram can be explained by molecular fractionation of mixed gas consequently the bernard parameter may be misleading when applied to mud volcanoes since it does not always reflect the original gas composition the mechanisms of the molecular advective segregation should be studied quantitatively by specific models and experiments

elastic wave velocities in rocks from a lower crustal section in southern calabria italy compressional and shear wave velocities vp and vs have been measured on 14 rock samples recovered from a high grade metamorphic terrane in the southern part of the calabrian massif which is considered to represent a continuous section of a former deep continental crust the experiments have been carried out in a cubic anvil apparatus at constant confining pressures up to 600 mpa and temperatures ranging from 20 to 700 c using the ultrasonic transmission technique at 600 mpa the compressional and shear wave velocities range from 6 33 km s 1 to 7 74 km s 1 and from 3 54 km s 1 to 4 30 km s 1 respectively variations in velocity are strongly related to variations in mineralogy both vp and vs increase with increasing amphibole pyroxene garnet and sillimanite content the range of velocities measured in the granulite facies rocks under conditions of lower crustal depth is similar to the range of seismic velocities for the crust beneath calabria importantly the metapelite rocks with intermediate silica and high alumina contents have in situ compressional and shear wave velocities which are equivalent to the mafic rocks or even significantly higher the detected high velocity layer at a depth between 15 and 20 km can be explained by a sequence of garnet cordierite sillimanite gneisses for which actual velocities between 6 6 and 7 6 km s 1 have been determined experimentally

an exact solution for ideal dam break floods on steep slopes dam break floods on steep slopes occur in diverse settings they may result from failure of either natural or man made dams and they have been responsible for the loss of thousands of lives costa 1988 recent disasters resulting from dam break floods on steep slopes include those at fonte santa mines portugal in november 2006 and taum sauk missouri usa in december 2005 numerical solutions of the shallow water equations are generally used to predict the behavior of dam break floods but exact analytical solutions suitable for testing these numerical solutions have been available only for floods with infinite volumes horizontal beds or both computational models used to simulate dam break floods commonly produce numerical instabilities and or significant errors close to the moving front when steep slopes and or irregular terrain are present in the flood path in part these problems reflect the complex interaction of phenomena not included in model formulation e g intense sediment transport under timedependent flow conditions but in part they also reflect shortcomings in the numerical solution algorithms themselves therefore it is important to obtain exact analytical solutions of the shallow water equations that can be used to test the robustness of numerical models when they are applied to floods of finite volume on steep slopes this paper presents a new solution for this purpose

looking into a volcanic area an overview on the 350 m scientific drilling at colli albani rome italy abstract a 350 m deep borehole was drilled in the colli albani volcanic district central italy in order to understand the shallow crust structure beneath the volcanic complex characterize the rock physical properties especially through in situ measurements and afterward laboratory experiments assess the local present day stress field install a broad band seismometer at depth the borehole is located adjacent to the western rim of the tuscolano artemisio caldera where several phenomena of unrest recently occurred in 1989 90 a seismic swarm affected this area and a related uplift was recognized in addition high gas concentrations mainly co 2 and h 2 s in aquifers and soils caused illnesses and casualties among inhabitants and animals in the past we describe the investigations carried out at the drill site and the results achieved from data analysis wire line drilling produced a complete stratigraphic record of the quaternary volcanic units down to the plio pleistocene sedimentary sequence and geophysical logs allowed a characterization of the rock physical properties from a tectonic point of view data provided by dipmeter and borehole televiewer were used for investigations on the recent and present day stress field and the results are compared to those available in the literature in the volcanic units we recognized two main fracture systems sw and nw dipping several faults intersecting the borehole show planes with oblique striae indicating a prevalent strike slip component of the movement finally borehole breakout analysis defined an active stress field with a e w oriented minimum horizontal component at the end of the drilling a blow out occurred due to pressurized fluids trapped into the sandy unit drilled in the last few meters of the hole sampling these fluids gave an additional value to the borehole providing information about the deep volcanic circulation and its possible connection to a deep seated magma chamber the main results show water with a na hco 3 chemistry and the highest salinity ever recognised in the area electrical conductivity 10 12 ms cm stable o and h isotopes reveal a meteoric origin of water and the absence of tritium points out a long residence time in the aquifer emitted gas is co 2 dominated with n 2 as second most important component helium isotopic composition of the gas allows us to estimate a magmatic component ranging in the interval 40 50 one of the highest in the colli albani carbon isotopes of co 2 0 53 vs pdb suggest that it could derive partly from a magmatic source and partly by the thermal decarbonation of the carbonatic basement

a 9170 year record of decadal to multi centennial scale pluvial episodes from the coastal southwest united states a role for atmospheric rivers abstract a well dated 9170 calendar year before present cal yr bp paleohydrologic reconstruction is presented from lower bear lake in the san bernardino mountains of the coastal southwest united states this new multi proxy record is characterized by alternating organic rich carbonate rich sediment units interpreted to reflect hydrologically forced changes in the lake s depositional environment our interpretation of the proxy data indicates nine decadal to multi centennial pluvial episodes pe over the past 9170 cal yr bp of these nine inferred pluvials five are interpreted as more pronounced based on their combined proxy interpretations pe v 9170 8250 pe iv 7000 6400 pe iii 3350 3000 pe ii 850 700 and pe i 500 476 top of core cal yr bp the lower bear lake record indicates that the san bernardino mountains source region for the mojave river and its terminal playa was wet during the same periods within dating errors to several of the major pluvials proposed from the lakes in the sink of the mojave river our comparison extends north also to tulare lake which drains the southcentral western sierra nevada mountains this temporally and spatially coherent signal indicates that a similar climate forcing acted to increase regional wetness at various times during the past 9170 cal yr bp as originally proposed by enzel ely and colleagues e g enzel et al 1989 enzel 1992 ely et al 1994 enzel and wells 1997 we too contend that holocene pluvial episodes are associated with changing the frequency of large winter storms that track across a broad region at decadal to multi centennial timescales we build upon their hypothesis through the addition of new and better dated site comparisons recent advances in the understanding of atmospheric rivers and improved knowledge of the ocean atmosphere dynamics that caused the early 20th century western united states pluvial

fluid geochemistry and geothermometry in the western sector of the sabatini volcanic district and the tolfa mountains central italy abstract a geochemical survey of 197 fluid discharges cold and thermal waters and bubbling pools and 15 gas emissions from the western sector of the sabatini volcanic district and the tolfa mountains latium central italy was carried out in 2007 2008 the chemical and isotopic compositions of the fluid discharges indicate the occurrence of two main sources 1 relatively shallow aquifers with ca na k hco 3 and ca mg hco 3 compositions when trapped in volcanic and sedimentary formations respectively and 2 a deep reservoir which is hosted in the mesozoic carbonate sequence rich in co 2 and having a ca so 4 hco 3 composition dissolution of a co 2 rich gas phase into the shallow aquifers produces high tds and high pco 2 cold waters while oxidation of deep derived h 2 s to so 4 2 generates low ph the 13 c co 2 values for gas emissions from 2 8 to 2 7 vs vpdb suggest that the origin of co 2 associated with the deep fluids is mainly related to thermo metamorphic reactions within the carbonate reservoir although significant mantle contribution may also occur however r r a values 0 37 0 62 indicate that he is mainly produced by a crustal source with a minor component from a crust contaminated mantle on the basis of the 13 c ch 4 and d ch 4 values from 25 7 to 19 5 vs vpdb and from 152 to 93 4 vs vsmow respectively ch 4 production is associated with thermogenic processes possibly related to abiogenic co 2 reduction within the carbonate reservoir the 34 s h 2 s values from 9 3 to 10 4 vs vcdt are consistent with the hypothesis of a sedimentary source of sulfur from thermogenic reduction of triassic sulfates geothermometric evaluations based on chemical equilibria co 2 ch 4 and separately h 2 s suggest that the reservoir equilibrium temperature is up to 300 c the d and 18 o data indicate that water recharging both the shallow and deep aquifers has a meteoric origin fluid geochemistry coupled with gravimetric data and tectonic lineaments supports the idea that significant contributions from a deep seated geothermal brine are present in the stigliano thermal fluid discharges exploration surveys investigated this area during 70 s 90 s for geothermal purposes nevertheless presently the area is still under exploited the presence of thermal waters and anomalous heat flow together with the demographic growth of the last years makes this site a suitable location for direct applications of the geothermal resource

origin of carbon in fumarolic gas from island arcs abstract we have measured 3 he 4 he ratios 13c values and co 2 3 he ratios of fumaroles and hot spring gases in three volcanic areas in japan the 3 he 4 he ratios 13c values and co 2 3 he ratios vary from 02 05 ratm 9 7 to 2 7 and from 7 74 109 to 1 18 1011 respectively based on these data and those in the literature we present the first quantitative estimates of the upper mantle sediment and limestone including slab components in co2 of volcanic and hydrothermal fluids from subduction zones taking compiled c isotopic data of limestone and organic sediment assuming that the co 2 3 he ratio and 13c value of mid ocean ridge basalt morb are representative of the upper mantle component and that later isotopic and elemental fractionations are minimal it is possible to deconvole each fraction of c on the basis of simple mixing equations up to 20 of the carbon in high temperature volcanic gases in subduction zones is derived from a morb type source while the major fraction of the gases is attributable to co2 produced by decarbonation of subducted marine limestone and slab carbonate

lower crustal thinning in the rhinegraben implications for recent rifting seismic near vertical and undershooting experiments carried out in the southern upper rhinegraben area between 1984 and 1991 show pronounced lateral variations of deep crustal properties significant differences in the apparent thickness of the reflective lower crust and the transparent upper crust appear to be related to different structural settings a 12 to 14 km thick reflective lower crust beneath a 15 km thick transparent upper crust of the eastern graben shoulder black forest probably originated during permo carboniferous reequilibration of thickened variscan orogenic crust thinning of this lower crust by about 5 km beneath the graben and rifted domains transitional between graben and shoulder the dinkelberg block is interpreted to be related to cenozoic extensional faulting a discrepancy between moderate extension of upper crust and lower crustal geometry indicates mechanical decoupling at depth during extension congruent modification of other physical properties is suggested by strong single reflective elements in the topmost parts of the thinned lower crust in the transitional dinkelberg block such an anomalously strong reflector occurs at a depth of 20 km below a pronounced local maximum of earthquake activity it is interpreted to be the presently active zone of decoupling which in time shifted from the rift axis to the eastern transition area

the importance of hydraulic groundwater theory in catchment hydrology the legacy of wilfried brutsaert and jean yves parlange based on a literature overview this paper summarizes the impact and legacy of the contributions of wilfried brutsaert and jean yves parlange cornell university with respect to the current state of the art understanding in hydraulic groundwater theory forming the basis of many applications in catchment hydrology ranging from drought flow analysis to surface water groundwater interactions hydraulic groundwater theory simplifies the description of water flow in unconfined riparian and perched aquifers through assumptions attributed to dupuit and forchheimer boussinesq 1877 derived a general equation to study flow dynamics of unconfined aquifers in uniformly sloping hillslopes resulting in a remarkably accurate and applicable family of results though often challenging to solve due to its nonlinear form under certain conditions the boussinesq equation can be solved analytically allowing compact representation of soil and geomorphological controls on unconfined aquifer storage and release dynamics the boussinesq equation has been extended to account for flow divergence convergence as well as for nonuniform bedrock slope concave convex the extended boussinesq equation has been favorably compared to numerical solutions of the three dimensional richards equation confirming its validity under certain geometric conditions analytical solutions of the linearized original and extended boussinesq equations led to the formulation of similarity indices for baseflow recession analysis including scaling rules to predict the moments of baseflow response validation of theoretical recession parameters on real world streamflow data is complicated due to limited measurement accuracy changing boundary conditions and the strong coupling between the saturated aquifer with the overlying unsaturated zone however recent advances are shown to have mitigated several of these issues the extended boussinesq equation has been successfully applied to represent baseflow dynamics in catchment scale hydrological models and it is currently considered to represent lateral redistribution of groundwater in land surface schemes applied in global circulation models from the review it is clear that wilfried brutsaert and jean yves parlange stimulated a body of research that has led to several fundamental discoveries and practical applications with important contributions in hydrological modeling

abiotic methane on earth 1 over the last 30 years geochemical research has demonstrated that abiotic methane ch4 formed by chemical reactions which do not directly involve organic matter occurs on earth in several specific geologic environments it can be produced by either high temperature magmatic processes in volcanic and geothermal areas or via low temperature 100 c gas water rock reactions in continental settings even at shallow depths the isotopic composition of c and h is a first step in distinguishing abiotic from biotic including either microbial or thermogenic ch4 herein we demonstrate that integrated geochemical diagnostic techniques based on molecular composition of associated gases noble gas isotopes mixing models and a detailed knowledge of the geologic and hydrogeologic context are necessary to confirm the occurrence of abiotic ch4 in natural gases which are frequently mixtures of multiple sources although it has been traditionally assumed that abiotic ch4 is mainly related to mantle derived or magmatic processes a new generation of data is showing that low temperature synthesis related to gas water rock reactions is more common than previously thought this paper reviews the major sources of abiotic ch4 and the primary approaches for differentiating abiotic from biotic ch4 including novel potential tools such as clumped isotope geochemistry a diagnostic approach for differentiation is proposed

isotopic evidence from the ivrea zone for a hybrid lower crust formed by magmatic underplating the large mafic complex overlying mantle peridotites in the ivrea zone of northern italy originated by underplating of mantle derived magma onto the base of continental crust and may be a unique outcrop of typical mafic lower crust sampled elsewhere only by mafic xenoliths neodymium and strontium isotope data show that the magmas assimilated large and roughly uniform proportions of crustal material the resulting hybrid magmas have the same isotopic signature as and may represent the lower crustal roots of upper crustal hercynian granitoid intrusions

kinematic subsurface stormflow this paper builds on the analysis of henderson and wooding 1964 in comparing simplified models of subsurface stormflow for the case of a sloping soil mantle in which the hydraulic conductivity is constant throughout it is shown that models based on a kinematic wave formulation may be good approximations for those based on the extended dupuit forchheimier assumptions for values of the nondimensional parameter 4i cos k sin2 less than about 0 75 in terms of predicting both water table profiles and subsurface stormflow hydrographs by using this critical value of the range of values of slope angle and saturated hydraulic conductivity for which the kinematic approximation is valid can be specified a comparison is made with slope angles and hydraulic conductivities at field sites where subsurface stormflow has been shown to be an important component of catchment storm response it is concluded that the kinematic approximation may be useful for cases of practical interest

diagenetic compaction experiments on simulated anhydrite fault gouge under static conditions faults that crosscut subsurface co2 storage systems offer potential leakage pathways especially if fault reactivation and dilation occur after reactivation however newly formed fault gouge is expected to gradually compact and seal as a function of time to estimate the time scale on which this occurs the processes that control compaction must be understood we performed uniaxial compaction experiments on simulated anhydrite fault gouge to investigate the deformation mechanisms that operate under postslip conditions in faulted anhydrite caprocks this involved constant stress 5 12 mpa and stress stepping experiments 5 7 5 10 mpa performed at 80 c under dry and wet conditions on fault gouge samples prepared from crushed natural anhydrite sieved into different grain size fractions in the range 20 500 m dry samples showed little to no compaction creep whereas wet samples i e flooded with presaturated caso4 solution showed rapid compaction our mechanical data and microstructural observations on wet samples suggest that for fine grain sizes 50 m and low stresses gouge compaction is controlled by diffusion controlled pressure solution with increasing grain size and stress fluid assisted subcritical microcracking becomes dominant pressurizing solution flooded samples with co2 15 mpa led to no significant effect on compaction rates in fine grained material but it decreased compaction rates in coarse samples since fine grain sizes are expected in reactivated faults we infer that pressure solution will dominate in anhydrite cap rocks with extrapolation of our lab data to reservoir conditions suggesting sealing time scales of a few decades

a newly emerged august 2013 artificially triggered fumarole near the fiumicino airport rome italy abstract early in the morning of 24 august 2013 following by hours the drilling of a shallow borehole in the same spot a new fumarole producing emissions of co2 rich gas water and mud suddenly appeared at a crossroad along the fenced area of the fiumicino international airport of rome italy similar episodes have been scientifically documented or simply reported in recent and past years to understand why gases are easily entrapped in the shallow subsurface of the fiumicino area we used five borehole cores drilled by us analyzed the stratigraphy of these and other nearby cores acquired a 2d seismic refraction tomogram and performed chemical and isotopic analyses of water samples collected from aquifers intercepted by two drilled boreholes our boreholes were realized with proper anti gas measures as while drilling we recorded the presence of pressurized gases at a specific permeable gravel level results show that in the study area gases become mainly entrapped in a mid pleistocene gravel horizon at about 40 50 m depth this horizon contains a confined aquifer that stores the endogenous upwelling gases the gravel is interposed between two silty clayey units the lower unit very hard and overconsolidated is affected by fractures that allow ascending gases to bypass the otherwise impermeable shale permeate the gravel and dissolve into the aquifer in contrast the upper unit is impermeable to fluids and seals the gas pressurized aquifer which therefore constitutes a source of hazard during human activities such as well drilling quarrying and various building related excavations as the stratigraphy of the fiumicino area is very common in large portions of the densely populated roman area and as the adjacent volcanic districts are hydrothermally active we conclude that phenomena similar to that observed at fiumicino could again occur both at fiumicino and elsewhere in the surrounding region as a prompt confirmation of our conclusion we signal that while writing this paper new artificially triggered degassing phenomena occurred off fiumicino in connection with the construction of the new harbor

accurate approximate semi analytical solutions to the boussinesq groundwater flow equation for recharging and discharging of horizontal unconfined aquifers abstract the boussinesq equation is usually used to describe one dimensional unconfined groundwater movement solutions of this equation are important as they provide useful insights regarding the water table response to stream level variations and allow us to quantify the exchange flow between the stream and the aquifer due to the nonlinearity of the boussinesq equation the solutions are generally obtained using numerical methods however for certain classes of initial and boundary conditions there are both exact and approximate analytical solution techniques this work focuses on the latter approach a new mathematical technique for approximate solutions of the boussinesq equation describing flow in horizontal unconfined aquifers induced by sudden change in boundary head is presented the method applies to the problems of recharging and dewatering of an unconfined aquifer and approximate solutions to both problems are derived the solutions were obtained by introducing an empirical function with four parameters which might be obtained using a numerical fitting procedure results based on this technique were found to be easily calculated and to be in good agreement with those obtained using numerical calculation based on runge kutta approach a benchmark between the proposed solutions and five existing approximate analytical solutions shows that the present solutions are the most accurate approximate solutions among those tested applications of the solutions are presented in the context of estimating aquifer hydraulic parameters

seismic and tectono metamorphic characters of the lower continental crust in phanerozoic areas a consequence of post thickening extension deep seismic profiles of phanerozoic continental crust commonly show a highly reflective lower crust rheological considerations suggest that the seismic fabric of the lower crust can be attributed to the tectonic transposition of various petrological heterogeneities in the main flow plane the variscan provinces of western europe have been affected during phanerozoic times by several extensional and compressional events the geometrical relationships between seismic and geological structures indicate that the layering of the lower crust was acquired during the late carboniferous to permian when the thickened variscan crust was affected by gravitational collapse petrological and geochronological analyses of deep crustal rocks xenoliths and exposed sections indicate that the lower crust has recorded a major high t medium p granulite facies metamorphism during the late variscan extension whereas on the surface upper carboniferous to permian basins were being deposited a similar scenario characterizes other phanerozoic orogenic belts in the caledonian provinces of the british islands the lower crust is seismically reflective it has undergone medium p granulitic metamorphism during the deposition of devonian sedimentary basins at the end of the caledonian orogeny in the same way collapse of the mesozoic belt in the western part of north america is responsible during the cenozoic for pervasive crustal extension whose consequence is a seismic layering of the lower crust accompanied by a low p granulite grade metamorphic event while in the mid and upper crusts low angle ductile normal faults give rise to the basin and range province therefore it is proposed that there is a genetic relationship between 1 post thickening crustal extension 2 low to medium p granulite facies metamorphism of the lower crust and 3 seismic layering of the lower crust

late time drainage from a sloping boussinesq aquifer numerical solutions to the nonlinear boussinesq equation applied to a steeply sloping aquifer and assuming uniform hydraulic conductivity indicate that late time recession discharge decreases nearly linearly in time when recession discharge is characterized by dq dt aqb this is equivalent to constant dq dt or b 0 this result suggests that a previously reported exponential decrease with time b 1 of modeled recession discharge from a similar sloping aquifer represented by the same equation appears to be an artifact of the numerical solution scheme and its interpretation because the linearly decreasing recession discharge b 0 is not known from field studies these findings challenge the application of a nonlinear boussinesq framework assuming uniform conductivity and geometric similarity to infer hydraulic properties of sloping aquifers from observations of streamflow this finding also questions the validity of the physical interpretation of the exponential decline in late time resulting from the commonly used linearized form of the boussinesq equation opposed to the full nonlinear equation when applied under these conditions for this reason application of the linearized equation to infer hydraulic properties of sloping aquifers is also challenged even if the observed recession is consistent with that of the linearized boussinesq equation

gas blowout from shallow boreholes at fiumicino rome induced hazard and evidence of deep co2 degassing on the tyrrhenian margin of central italy abstract a borehole drilled at fiumicino rome down to only 27 m depth in a zone where no gas emission at the surface was known caused a gas blowout from a pressurized gas pocket confined beneath a clay cover gas slowly diffused from the borehole within superficial permeable sand seven persons living in three ground floor flats of a near building had to be hospitalized due to co2 exposure all the houses in the proximity were evacuated at the request of the fire brigade two additional boreholes were drilled nearby hoping that this could rapidly exhaust the gas stored underground to the contrary the soil gas flux near houses increased and indoor co2 air concentration rapidly rose to lethal values 15 to 30 vol as a remediation we suggested to restore the continuity of the impervious gas cover by squeezing quick setting cement into the formation through new boreholes to be drilled near the existing ones although the first cement squeeze reduced drastically the co2 soil flux and indoor concentration six additional squeezes had to be carried out in order to lower the gas emission below the gas hazard threshold the gas was mostly made of co2 98 vol with minor n2 and ch4 its chemical and isotopic composition 13cco2 1 55 3he 4he 0 314 ra is similar to that of the gas manifestations of mts sabatini and alban hills volcanic areas though being somewhat contaminated by crustal and shallow organic volatiles these gases likely have a component originated in the mantle that beneath the volcanic roman comagmatic province is probably deeply contaminated with crustal material the fiumicino gas blowout indicates that the area of central italy characterized by strong co2 degassing extends westerly to include the tyrrhenian coast

crustal xenoliths from cenozoic volcanic fields of west germany implications for structure and composition of the continental crust crustal xenoliths in three cenozoic volcanic fields of west germany the northern hessian depression nhd the eifel and the urach hegau include medium to high grade meta sedimentary and felsic to mafic meta igneous rocks also present in all three suites are pyroxenites and hornblendites for each volcanic field a model crustal profile is proposed based on calculated or measured p wave velocities of xenoliths and depth vp relationships egt central segment and rhenish massif traverses the xenolith lithologies from the nhd and the eifel show some similarities the middle crust between the depths of about 10 and 25 km consists mainly of meta sediments felsic gneisses and granulites meta sedimentary rock types are particularly abundant in the eifel at depths of between about 5 and 15 km but are less common within the nhd xenolith collection the felsic gneisses range from meta granites to meta tonalites i and s type eifel meta sediments range from meta pelites to meta greywackes and meta quartzites the nhd xenolith suite contains a few highly depleted granulite facies meta sedimentary fragments at depths between 24 and 26 km the increase in vp from about 6 8 to 8 km s 1 28 34 km is correlated with the presence of mafic granulites intercalated with eclogites pyroxenites and hornblendites beneath north hessia the granulite layer problably grades into a composite eclogite peridotite layer at the lower part of this transition zone the crust beneath the urach hegau consists largely of meta sediments with subordinate felsic meta igneous rocks most of the meta sedimentary samples seem to be depleted in felsic components suggesting intra crustal differentiation by partial melting the urach crust contains lithologies which are similar to the outcropping moldanubian type para gneisses of the black forest mafic and ultramafic xenoliths from the urach hegau differ in their mineralogy and chemical composition from the eifel and nhd mafic granulites they represent meta cumulates derived from alkaline magmas which intruded the base of the crust and underwent deformation and recrystallization petrographic and chemical differences between urach hegau and eifel nhd are believed to reflect the contrasting styles of crustal evolution in the rhenohercynian and the moldanubian belts of the variscan orogen

helium strontium isotope constraints on mantle evolution beneath the roman comagmatic province italy european social fund scottish universities carnegie trust for the universities of scotland

mantle derived co2 migration along active faults within an extensional basin margin fiumicino rome italy abstract fluid migration along faults can be highly complex and spatially variable with the potential for channeled flow accumulation in capped porous units fault cross flow lateral migration along strike or complete sealing extensional basin margins can be important for such migration given the associated crustal thinning and decompression that takes place combined with potential geothermal or mantle gas sources one such example is near the urban area of rome situated along the active extensional continental margin of the tyrrhenian back arc basin and surrounded by middle upper pleistocene k rich and arc related volcanoes recent research activities in the area around fiumicino a town 25 km to the west of rome has highlighted the close spatial link between degassing co 2 and the faults that provide the necessary vertical migration pathways in particular detailed soil gas and gas flux surveys have highlighted the release at surface of large volumes of asthenospheric mantle co 2 in correspondence with normal faults observed in a new seismic reflection profile acquired along the tiber river detailed reconstruction of the pleistocene holocene stratigraphy of the area dates fault activity from 20 000 to 9000 years bp it is proposed that the gas migrates preferentially along the cataclastic tectonic breccias of the faults until it encounters recent unconsolidated sediments porous units within this shallow stratigraphy act as temporary secondary traps for the leaking gas with local gas release at the ground surface occurring where the sealing of the overlying aquitards has been compromised degassing and active faults confirm the extensional tectonics affecting the area and the geodynamic scenario of a mantle wedge beneath the western apennines associated with ongoing w directed subduction moreover degassing highlights the potential geochemical and seismic risks for the highly populated urban areas near rome

rupture creep lamellae and crocodiles happenings in the continental crust from the observation of certain seismic reflectivity patterns in phanerozoic continental crusts a relationship is suggested between 1 rupture and seismicity generally restricted to the upper crust 2 crocodile tectonics a kind of vertical indentation observed by diverging plane reflectors preferably in the middle crust 3 creep and the formation of reflecting lamellae in the lower crust based on these observations and on viscosity depth estimates a conceptual model for the above mentioned structures is presented which is also compatible with observations in older crusts boundary conditions are given for rupture as well as for lamellae forming creep

sediment pulse evolution and the role of network structure abstract sediment pulses are triggered through a variety of mechanisms from landslides to land use change how do these pulses move through the fluvial system and how do they evolve in a system with perfect sediment connectivity the erosional response to a perturbation and the resulting signal at the river mouth would match however this rarely occurs many studies have addressed reach scale dynamics of sediment pulses and how they translate or disperse downstream at the watershed scale network structure and storage become more important in modulating the sediment signal here we review the current literature on sediment pulse behavior and then address the role of network structure on maintaining dispersing or transforming sediment pulses in a fluvial system we use a reduced complexity network routing model that simulates the movement of bed material through a river basin this model is run in the greater blue earth river gber basin in minnesota usa first with spatially uniform inputs and then with inputs constrained by a detailed sediment budget once the system reaches equilibrium a sediment pulse is introduced first at a single location and then throughout the system and tracked as it evolves downstream results indicate that pulses able to translate downstream disperse in place upon arriving at over capacity reaches as sediment goes into storage in the gber basin these zones occur just upstream of a knickpoint that is propagating upstream through all mainstem channels as the pulses get caught in these sediment bottlenecks there is a decoupling of the original pulse of sediment and the resulting bed material wave these results show that the network structure both in terms of network geometry and the spatial pattern of transport capacity can play a dominant role in sediment connectivity and should be considered when predicting sediment pulse behavior at the watershed scale

hidden sinkholes and karst cavities in the travertine plateau of a highly populated geothermal seismic territory tivoli central italy abstract sinkholes and other karst structures in settled carbonate lands can be a significant source of hazard for humans and human works acque albule the study area of this work is a plio pleistocene basin near rome central italy superficially filled by a large and thick deposit of late pleistocene thermogene travertine human activities blanket large portions of the flat territory covering most evidence from geological surface processes and potentially inducing scientists and public officials to underestimate some natural hazards including those connected with sinkholes to contribute to the proper assessment of these hazards a geomorphologic study of the basin was performed using digital elevation models dems recent aerial photographs and field surveys historical material such as old aerial photographs and past geomorphologic studies both pre dating the most part of quarrying and village building was also used together with memories of the elderly population this preliminary study pointed out the presence of numerous potentially active sinkholes that are at present largely masked by either quarrying or overbuilding where this first study pointed out the apparent absence of sinkholes in areas characterized by high density of buildings a detailed subsurface study was performed using properly calibrated electrical resistivity tomography ert and dynamic penetration measurements dpsh together with some borehole logs made available from the local municipality this second study highlighted the presence of sinkholes and caves that are this time substantially hidden to the resolution of standard methods and materials such as aerial photographs dems and field surveys active sinkhole subsidence in the acque albule basin may explain at least in part the frequent damages that affect numerous buildings in the area the main conclusion from this study is that the mitigation of sinkhole hazard in highly populated areas has to pass through a thorough search of hidden sinkholes that can be masked by the anthropocenic molding and blanketing of the territory for these purposes data from historical pre anthropocene documents as well as where possible subsurface investigations are fundamental

spatial domain analysis of carbon dioxide from soils on vulcano island implications for co2 output evaluation abstract the carbon dioxide emissions of volcanoes have been targeted as effective contributors of co 2 to the atmosphere however different sources can be effective and active at the same time in the generation and release of co 2 in volcanic zones since isotopic fingerprinting of co 2 allows the precise identification of different sources coupling carbon isotope and co 2 flux measurements enables the evaluation of the mass contribution of each source to the carbon dioxide emissions this paper accounts for the first extensive spatial analysis of coupled measurements of carbon isotopologues of co 2 in the soil gases and co 2 fluxes discharged by soils on vulcano island an innovative method has been designed tested and fine tuned in the laboratory to measure 13 c co 2 values directly in field using a new type of laser based isotopologues analyzer namely a deltaray thermo fisher scientific the method can be used to determine the carbon isotope composition across the full range of co 2 concentrations in the soil gases 0 100 vol these data have been combined with measurements of the co 2 contents in the soil gases to distinguish co 2 from deep origins from co 2 of biogenic origin in the inhabited area of vulcano porto the method of evaluating the amount of deep origin co 2 in the soil gases is widely applicable in volcanic and geothermal zones for evaluation and monitoring purposes for both gas and volcanic hazards

a review of the stratigraphy of rome italy according to geochronologically and paleomagnetically constrained aggradational successions glacio eustatic forcing and volcano tectonic processes abstract in this paper we provide a critical review of the studies conducted on the geology of rome since the first half of the 20th century aimed at presenting an updated state of the art on the stratigraphy of this area following this introductory summary we present a complete reconstruction of the geological evolution and the resulting chrono litho stratigraphic setting of the greater area of rome according to a series of works that in the last 20 years have adopted an innovative methodological approach based on the conceptual model of aggradational successions deposited in response to sea level rise during the glacial terminations and on the strict geochronologic constraints to the sedimentary record achieved by paleomagnetic investigation of clay sections and 40ar 39ar dating of interbedded volcanic materials we also present a complete overview on the chronostratigraphy of the two volcanic districts of colli albani and monti sabatini located se and nw of rome respectively that has been achieved integrating the field work with the large number of radiometric ages provided in these years on their eruptive products moreover we propose a revised stratigraphic column to compare the most recent official 1 50 000 and 1 10 000 geologic mapping of rome which is intended as a tool of correlation for an international audience of quaternary scientists to approach the study of this area a detailed discussion of the proposed revisions is also provided as supplementary information to this paper

gas blowout from shallow boreholes near fiumicino international airport rome gas origin and hazard assessment abstract in summer 2013 a toxic and polluting gas blowout 19 tonnes day 1 co2 95 kg day 1 ch4 occurred from two shallow boreholes drilled at only 50 m from the international airport of rome italy in the town of fiumicino another gas blowout occurred in the same period from a borehole located offshore 2 km away also generating sea water acidification it lasted only a couple of days onshore co2 was also diffusing from holes within the soil particularly toward the airport generating a soil flux up to 1 8 tonnes day 1 in 3 5 months 1500 tonnes of co2 and 5 4 tonnes of ch4 were emitted in the atmosphere temporal monitoring of gas geochemistry indicates that in this area a mixing occurs between shallow and pressurized gas pockets co2 dominated but with different chemical i e he ch4 ratio and isotopic 3he 4he 13c dch4 characteristics numerical simulation of co2 dispersion in the atmosphere showed that dangerous air co2 concentrations up to lethal values were only found near the vents at a height of 0 2 m fiumicino is a high blowout risk area as co2 rising through deep reaching faults pressurizes the shallow aquifer contained in gravels confined underneath shales of the tiber delta deposits the fiumicino blowout is a typical example of dangerous phenomenon that may occur in urban context lying nearby active or recent volcanoes and requires quick response on hazard assessment by scientists to be addressed to civil protection and administrators

groundwater response to changing water use practices in sloping aquifers 1 groundwater flow is examined for recharge and extraction within a sloping aquifer fundamental equations are commonly formulated either in s n coordinates where s is tangent to the base or in x z coordinates where x is horizontal consistency between these two formulations is achieved here by incorporating the slope of the base directly into the hydraulic conductivity and aquifer diffusivity terms a stepping model is developed for steady and transient flow and comparisons between stepping and sloping models show that the stepping model approaches the exact solutions as the number of steps increases this model is used to develop a set of nomographs and dimensionless parameters relating drawdown over time to distance upgradient or downgradient from a point of water use while upgradient and downgradient responses differ with respect to the quantity of water removed or injected it is shown that the response proportional to the change in saturated thickness is the same in both directions

the unit response of groundwater outflow from a hillslope subsurface flow from a hillslope can be described by hydraulic groundwater theory as formulated by the boussinesq equation solution of its linear version brings out some of the essential features of this phenomenon arbitrary inputs can be accommodated by simple convolution of the sudden drawdown problem the relative magnitude of the driving mechanisms namely the streamwise pressure gradient resulting in diffusion and gravity i e slope resulting in advection can be determined by a simple dimensionless parameter

a note on groundwater flow along a hillslope 1 particular cases of groundwater flow along a hillslope are studied using the groundwater hydraulic theory e g dupuit approximation described by the boussinesq equation analytical solutions are found as simple transformations of known similarity solutions in particular the expressions for phreatic surface level and volume flux and the corresponding loop rating curve for the flow of a groundwater mound as well as the travelling wave solutions of the boussinesq equation are described in detail

sudden deep gas eruption nearby rome s airport of fiumicino 1 on 24 august 2013 a sudden gas eruption from the ground occurred in the tiber river delta nearby rome s international airport of fiumicino we assessed that this gas analogous to other minor vents in the area is dominantly composed of deep partially mantle derived co2 as in the geothermal gas of the surrounding roman comagmatic province increased amounts of thermogenic ch4 are likely sourced from meso cenozoic petroleum systems overlying the deep magmatic fluids we hypothesize that the intersection of ne sw and n s fault systems which at regional scale controls the location of the roman volcanic edifices favors gas uprising through the impermeable pliocene and deltaic holocene covers pressurized gas may temporarily be stored below these covers or within shallower sandy permeable layers the eruption regardless the triggering cause natural or man made reveals the potential hazard of gas charged sediments in the delta even at distances far from the volcanic edifices

groundwater response to changing water use practices in sloping aquifers using convolution of transient response functions 1 this study examines the impact of a sloping base on the movement of transients through groundwater systems dimensionless variables and regression of model results are employed to develop functions relating the transient change in saturated thickness to the distance upgradient and downgradient from recharge or withdrawal convolution of these transient response functions made possible due to linearity of partial differential equations in the model enables computation of changes in saturated thickness over recharge withdrawal that varies over space and time establishing the criteria and form of these functions led to the discovery of fundamental underlying properties upgradient and downgradient responses may be scaled to achieve a symmetrical relationship expressions are developed to compute change in saturated thickness at the location of water use and downgradient response at large times form a s shaped curve that effectively adds a diffusive component to the average velocity of the kinematic wave approximation where the hydraulic gradient is equal to the bed slope hydrogeologic data for three study regions in the high plains aquifer are summarized and model results are presented for changes in saturated thickness the transient response functions are used to reconstruct and interpret groundwater response to historical water use practices and to predict future changes in saturated thickness for a series of hypothetical alternative water use scenarios depressions in groundwater elevation are observed both upgradient and downgradient from areas of high water use however these depressions preferentially move downgradient over time and may continue to spread downgradient far into the future this approach quantifies and provides understanding of the impacts of changes in natural and anthropogenic hydrologic forcings on aquifer systems

channel planform change and detachment of tributary a study on the haora and katakhal rivers tripura india abstract the main objective of the paper is to find the probable causes behind the shifting course of the haora river one of the major rivers of west tripura and detachment of one of its major tributaries the katakhal river from a recent satellite image we observed that the river haora has changed its course drastically near the confluence earlier it used to take a sharp northward bend to meet with the river titas immediately after crossing the indo bangladesh border but presently it is flowing westward to do so moreover the katakhal river a right bank tributary of the river haora that used to flow through the northern side of the city of agartala and meet with the river haora at bangladesh is no longer a tributary of the haora river now it is completely detached from the haora river and meets with the river titas separately spatiotemporal maps have been used to detect the changes field investigation with the help of gps has been done in order to find the link between the haora river and the katakhal river within the indian territory changing patterns of the haora and katakhal river confluences are also analysed and earlier courses are identified the shifting trends of both of these two rivers are found along the flanks of the interfluvial area because of microscale tectonic activity i e upliftment of the interfluvial zone

deep co2 release revealed by stable isotope and diffuse degassing surveys at vulcano aeolian islands in 2015 2018 abstract the partitioning of carbon dioxide co2 released by soils at vulcano island aeolian islands italy was performed by combining the co2 flux and the carbon isotope measurements based on this method the amount of co2 of volcanic origin was quantified six times during the period 2015 2018 the data analysis allowed us to establish the correlation between co2 soil degassing and changes in the contribution of volcanic fluids carbon isotope determinations were performed in situ to enhance the coverage of data collection in space and time these data were combined with both the co2 contents in the ground gases and the soil co2 flux the amount of volcanic co2 was distinguished from that of biogenic origin by implementing a three component mixing model the results of this study indicate that the increase in co2 output in september 2018 reflects the increase in volcanic gas emissions the measurement method and analysis presented in this work are sufficiently general to be applicable to the monitoring programs of active volcanoes

extreme methane deuterium nitrogen and helium enrichment in natural gas from the homorod seep romania abstract methane ch 4 in terrestrial environments whether microbial thermogenic or abiogenic exhibits a large variance in c and h stable isotope ratios due to primary processes of formation isotopic variability can be broadened through secondary post genetic processes such as mixing and isotopic fractionation by oxidation the highest and lowest 13 c and 2 h or d deuterium concentrations in ch 4 found in various geologic environments to date are defined as natural terrestrial extremes we have discovered a new extreme in a natural gas seep with values of deuterium concentrations d ch4 up to 124 that far exceed those reported for any terrestrial gas the gas seeping from the small homorod mud volcano in transylvania romania also has extremely high concentrations of nitrogen 92 vol and helium up to 1 4 vol carbon isotopes in ch 4 c 2 h 6 and co 2 and nitrogen isotopes in n 2 indicate a primary organic sedimentary origin for the gas a minor mantle component is suggested by the 3 he 4 he ratio r ra 0 39 both thermogenic gas formation modeling and rayleigh fractionation modeling suggest that the extreme deuterium enrichment could be explained by an oxidation process characterised by a d ch4 and 13 c ch4 enrichment ratio h c of about 20 and may be accounted for by abiogenic oxidation mediated by metal oxides all favourable conditions for such a process exist in the homorod area where increased heat flow during pliocene quaternary volcanism may have played a key role finally we observed rapid variations within 1 h in c and h isotope ratios of ch 4 and in the h 2 s concentrations which are likely caused by mixing of the deep oxidized ch 4 n 2 h 2 s he rich gas with a microbial methane generated in the mud pool of one of the seeps we hypothesize that the unusual features of homorod gas can be the result of a rare combination of factors induced by the proximity of sedimentary organic matter mafic metal rich volcanic rocks and salt diapirs leading to the following processes a primary thermogenic generation of gas at temperatures between 130 and 175 c b secondary alteration through abiogenic oxidation likely triggered by the neogene quaternary volcanism of the eastern transylvanian margin and c mixing at the surface with microbial methane that formed through fermentation in the mud volcano water pool the homorod gas seep is a rare example that demonstrates how post genetic processes can produce extreme gas isotope signatures thus far only theorized and that extremely positive d ch4 values cannot be used to unambiguously distinguish between biotic and abiotic origin

baseflow separation based on analytical solutions of the boussinesq equation a technique for baseflow separation is presented based on similarity solutions of the boussinesq equation the method makes use of the simplifying assumptions that a horizontal impermeable layer underlies a dupuit aquifer which is drained by a fully penetrating stream the value of the baseflow maximum as well as the baseflow recession hydrograph can be estimated by fitting the analytical solutions of the boussinesq equation to the observed discharge values for individual flood events for the rising limb of the baseflow hydrograph a linear function is assumed for simplicity the method is first demonstrated on three watersheds for a total of five flood events and extensively applied over a three year period for the mahantango creek pennsylvania watershed the proposed method reduces some of the subjective aspects long associated with baseflow separation techniques

a way to hydrothermal paroxysm colli albani volcano italy the main issue addressed in this work is the process leading to fluid subsurface entrapment and pressure increase up to hydrofracturing and possibly to paroxysm in a hydrothermal setting in order to envisage such processes and mitigate their effects in the volcanically active study area and elsewhere a field and laboratory multidisciplinary approach is used in the fossil late pleistocene portion of an active hydrothermal system colli albani volcano rome italy in this area sulfate and sulfide mineralizations and strongly altered ignimbrites are exposed the alteration acme occurs on top of a buried normal fault where abundant degassing is still active and fades away in 2 3 km based on pervasive versus discrete alteration styles mineral assemblages and further evidence proximal and distal alteration domains are recognized both domains underwent steam heated advanced argillic alteration with likely temperatures up to 400 c in the proximal domain and less than 150 c in the distal domain the process of hydrothermal alteration progressively and severely depleted many elements from the most permeable rock units whereas the lowest permeable unit tufo lionato underwent fracture and porosity healing accompanied by both mass and volume gain in the proximal domain the advanced argillic hydrothermal alteration eventually formed a substantial barrier to fluids the hydrothermal fluids accumulated in and below this barrier which was then suddenly hydrofractured when heat driven hydraulic pressure overcame the effective stress thus possibly leading to hydrothermal paroxysm the decompression associated with hydrofracturing enhanced gas exsolution and mineral precipitation from the entrapped overpressured fluids mineral precipitation contributed in turn to fracture healing and to reinitiation of a new cycle of hydrothermal fluid entrapment the key preconditions for the occurrence of the inferred processes are the contrasting compositions of k alkaline host rocks and acidic alteration fluids as also previously documented in other similar settings elsewhere

origins of methane discharging from volcanic hydrothermal geothermal and cold emissions in italy abstract we have addressed the origins of methane in fumarolic thermal and cold emissions discharging from a diversity of geological settings spread all over the italian peninsula and at panarea and pantelleria islands fluid discharges from the main geothermal systems of the peri tyrrhenian area including mt amiata larderello latera and manziana show 13c ch4 and d ch4 values 28 v pdb and 160 v smow respectively and c1 c2 concentration ratios 1000 these patterns suggest that ch4 discharged from these systems is primarily generated by abiogenic reduction of co2 and or co methane seems to have at least partially a different origin than the higher hydrocarbons that might be entirely related to the thermal decomposition of organic matter or alternatively to methane polymerization fumaroles from the volcanic systems of solfatara vesuvio panarea and pantelleria have c1 c2 concentration ratios in a wide range from 17 to 4300 but 13c ch4 and d ch4 values 21 v pdb and 120 v smow respectively such isotopic values are very similar to those reported for ch4 discharging from ultramafic hydrothermal systems in agreement with recent evidence provided for solfatara and pantelleria we therefore infer that the ch4 in the volcanic fumaroles is mainly abiogenic too the 13c ch4 from 21 6 to 36 9 v pdb and d ch4 from 113 to 164 v smow values as well as the c1 c2 concentration ratios from 19 to 2240 in the co2 rich fluid discharges located between the geothermal volcanic systems and the apennine sedimentary chain tend to decrease eastwards as the temperatures of the fluid reservoirs progressively diminish suggesting that the ch4 production is mainly related to thermogenic processes according to this general trend the ch4 dominated fluids from mud volcanoes located eastwards of the co2 rich emissions are fed by an almost pure thermogenic source the easternmost fluid discharges from the po valley and the adriatic coast where organic matter evolves at relatively shallow depths in the presence of a low geothermal gradient record the lowest 13c ch4 and d ch4 values i e as low as 69 v pdb and