reservoir structure and wastewater induced seismicity at the val d agri oilfield italy shown by three dimensional vp and vp vs local earthquake tomography wastewater injection into a high rate well in the val d agri oilfield the largest in onshore europe has induced swarm microseismicity since the initiation of disposal in 2006 to investigate the reservoir structure and to track seismicity we performed a high spatial resolution local earthquake tomography using 1281 natural and induced earthquakes recorded by local networks the properties of the carbonate reservoir rock fracturing pore fluid pressure and inherited faults control the occurrence and spatiotemporal distribution of seismicity a low vp high vp vs region under the well represents a fluid saturated fault zone ruptured by induced seismicity high vp high vp vs bumps match reservoir culminations indicating saturated liquid bearing zones whereas a very low vp low vp vs anomaly might represent a strongly fractured and depleted zone characterized by significant fluid withdrawal the comprehensive picture of the injection linked seismicity obtained by integrating reservoir scale tomography high precision earthquake locations geophysical and injection data suggests that the driving mechanism is the channelling of pore pressure perturbations through a high permeable fault damage zone within the reservoir the damage zone surrounds a pliocene reverse fault optimally oriented in the current extensional stress field the ruptured damage zone measures 2 km along strike 3 km along dip and is confined between low permeability ductile formations injection pressure is the primary parameter controlling seismicity rate our study underlines that local earthquake tomography also using wastewater induced seismicity can give useful insights into the physical mechanism leading to these earthquakes

a detailed analysis of wastewater induced seismicity in the val d agri oil field italy the val d agri basin in the apennines seismic belt hosts the largest oil field in onshore europe high quality recordings from a temporary dense network unravel a swarm of 111 small magnitude events ml 1 8 occurred in june 2006 during the first stage of wastewater injection into a high rate well high precision relative locations define a preexisting blind fault located 1 km below the well inside fractured and saturated carbonates where wastewater is reinjected seismicity begins 3 h after the initiation of injection the seismicity rate strictly correlates with injection curves and temporal variations of elastic and anisotropic parameters seismicity is induced by rapid communication of pore pressure perturbations along a high permeability fault zone favorably oriented with respect to the local extensional stress field our accurate 3 d locations of 219 events ml 2 2 detected by the local operator network after june 2006 concentrate on the preexisting fault measuring 5 km along dip over the following 7 5 years the seismicity rate correlates with short term increases in injection pressure

variations of attenuation and vp vs ratio in the vicinity of wastewater injection a case study of costa molina 2 well high agri valley italy by analyzing seismicity induced by the injection of wastewater into the costa molina 2 well we characterized the attenuation in the area attenuation quality factors qp and qs were calculated using peak frequency method which is suitable for small magnitude earthquakes registered in the region anomalously high attenuation with values of effective qp 48 and qp qs ratio below 1 in the vicinity of the injection well was found in comparison with qp 60 for the rest of the region furthermore vp vs ratio was also found high in the close vicinity of the injection well we discuss how sedimentary rocks possibly change their geomechanical properties due to salt water injection and show that observed changes of attenuation increase and vp vs ratio increase are consistent with the geomechanical models and experiments our findings indicate that the observed anomaly in the vicinity of the costa molina 2 well is due to i changes of the properties of the rock mass affected by injection ii 3d structure in

evolution of the gypsum karst of sorbas se spain the gypsum karst of sorbas is developed within messinian gypsum characterized by an interbedded sequence of selenitic gypsum beds and marls this geological configuration has led to the development of an interstratal karst in which galleries have developed in the marl levels but not in the gypsum ones up to six cave passage levels have been detected in the gypsum caves following stratification planes between the impervious intercalated marls and the pervious gypsum strata the explanation for this lies in the hydrogeological history of the area initially the gypsum karst evolved as a multi layer semi confined aquifer under phreatic conditions enabling the formation of small proto conduits in the individual gypsum beds while the intervening marls and clays acted as impervious barriers during a second stage after lowering of the piezometric level vadose conditions were established in which mechanical erosion processes in the intercalated marls and clays became predominant this genetic duality means that the gypsum karst at sorbas can be taken as an example of interstratal karstification where the contemporary underground erosion processes and those of karstic evolution should be considered products of the hydrogeological development the total lowering of the piezometric level during the quaternary is at least of 120 m in the centre of the basin interstratal vadose caves more than 120 m below the surface possess phreatic proto channels in their upper levels which identify the past phreatic conditions in the genesis of the caves

long term erosion rate measurements in gypsum caves of sorbas se spain by the micro erosion meter method abstract the present work deals with the results of long term micro erosion measurements in the most important gypsum cave of spain the cueva del agua sorbas almeria se spain nineteen mem stations were positioned in 1992 in a wide range of morphological and environmental settings gypsum floors and walls carbonate speleothems dry conduits and vadose passages inside and outside the cave on gypsum and carbonate bedrocks and exposed to variable degree of humidity different air flow and hydrodynamic conditions four different sets of stations have been investigated 1 the main cave entrance las vinicas spring 2 the main river passage 3 the abandoned laboratory tunnel and 4 the external gypsum surface data over a period of about 18 years are available the average lowering rates vary from 0 014 to 0 016 mm yr 1 near the main entrance and in the laboratory tunnel to 0 022 mm 1 on gypsum floors and 0 028 mm yr 1 on carbonate flowstones the denudation data from the external gypsum stations are quite regular with a rate of 0 170 mm yr 1 the observations allowed the collecting of important information concerning the feeding of the karst aquifer not only by infiltrating rainwater but under present climate conditions also by water condensation of moist air flow this contribution to the overall karst processes in the cueva del agua basin represents over 20 of the total chemical dissolution of the karst area and more than 50 of the speleogenetically removed gypsum in the cave system thus representing all but a secondary role in speleogenesis condensation corrosion is most active along the medium walls being slower at the roof and almost absent close to the floor this creates typical corrosion morphologies such as cupola while gypsum flowers develop where evaporation dominates this approach also shows quantitatively the morphological implications of condensation corrosion processes in gypsum karst systems in arid zones responsible for an average surface lowering of 0 047 mm yr 1 while mechanical erosion produces a lowering of 0 123 mm yr 1

geochemical behaviour of ni cr cu zn and pb in an andosol cambisol climosequence on basaltic rocks in the french massif central abstract the objective of this study is to identify parameters influencing trace elements te vertical distributions in an andosol andic cambisol climosequence in order to understand processes involved in the current distribution of trace elements from basaltic rocks to associated soils six pedons developed on tertiary massive basaltic formations located at similar position in the hill slopes submitted to the same wet mountainous climate but under various microclimatic conditions altitude and annual rainfall were considered the six studied soils are andic and rich in organo metallic complexes two different and quantitative methods were used to compare the geochemical distributions of major and trace elements both being calculated with ti as invariant element isovolumetric mass balance and enrichment factors anthropogenic pedogenetic microclimatic inherited factors were discriminated anthropogenic influences are pointed out for k in two pedons and for pb in all studied sites distributions of other te are affected by discontinuities between underlying rocks and soil horizons zinc and cu distributions are controlled by organic matter whereas cr and ni distributions are influenced by pedogenetic processes results emphasize the relative trace element immobilization in andic soils under temperate climate

the micromorphology of gypsum and halite in reg soils the negev desert israel gypsum and halite are the most common salts in reg soils developed on alluvial parent material under extremely arid conditions in the negev desert israel the aim of this paper is to document the changes in the micromorphology of these salts at different stages of reg soil development on two alluvial fan chronosequences the micromorphological analyses included thin section observations and scanning electron microscope and electron microprobe analyses in this arid soil environment gypsum and halite possess a variety of crystal forms which may change with depth in a single profile and or between profiles of different ages the variety of crystal forms results from changes in the microenvironmental conditions that occur in desert reg soils over time poikilitic lenticular gypsum is found in all reg soils and is distributed throughout the profiles the conditions needed for such crystals to form are high ionic impurities and deposition in a void system where space is not limiting microcrystalline alabastrine gypsum is only found in mature reg soils and is crystallized when the profile has high amounts of fine material and a well developed desert pavement in a well developed reg soil profile indicators such as a well developed desert pavement and high amounts of fine earth limit the leaching depth and cause gypsum deposition from supersaturated soil solutions under high evaporation rates close to the surface prismatic and fibrous gypsum are less common low amounts of prismatic gypsum are found in young and mature soils while fibrous gypsum is found only in mature soils in re cemented shattered gravel the halite crystal form is mainly cubic with low amounts of host material incorporated into the crystal it occurs predominantly in mature reg soil profiles through the crystallization from supersaturated soil solutions at the depth of maximum water penetration although the alabastrine prismatic and fibrous gypsum and cubic halite are deposited in a displacive manner no correlation was found between their occurrence and the distribution of shattered gravel in the soil profile

bed sediment associated trace metals in an urban stream oahu hawaii of the 117 stream and lake systems sampled nationwide fish from manoa stream on oahu hawaii have consistently shown the highest pb concentrations therefore a detailed study was conducted to examine total metal contents in bed sediments from a 5 8 km stretch of manoa stream a total of 123 samples 63 m were examined for 18 elements and 14 samples for 21 elements selected samples were also examined using different leach solutions to examine metal phase associations all trace metal data computations of enrichment ratios and the modified index of geoaccumulation point to mineralogical control for cr and ni minor anthropogenic contamination for ba cd cu hg and zn and a very strong contamination signal for pb maximum pb contents up to 1080 mg kg 1 were associated with anthropogenic material dumping in minor tributaries storm sewer sediments and sediments in the lower section of the basin proportionally pb had the highest non residual component of elements examined dominantly in the reducible phase associated with mn and amorphous fe oxyhydroxides the contamination signal was typically lowest in the undisturbed headwater reach of the basin above 5 1 km with significant increases throughout the residential and commercial institutional zones of the mid basin the spatial pattern of bed sediment contamination and evidence from storm sewer outlet sediments strongly indicates that pb and to a lesser degree some other metals is still being transported to the stream and the primary agent is soil erosion and transport of metals sorbed to sediments the primary source of sediment associated metals is considered to be the automobile though other minor sources can not be ruled out

physical and transport property variations within carbonate bearing fault zones insights from the monte maggio fault central italy the physical characterization of carbonate bearing normal faults is fundamental for resource development and seismic hazard here we report laboratory measurements of density porosity vp vs elastic moduli and permeability for a range of effective confining pressures 0 1 100 mpa conducted on samples representing different structural domains of a carbonate bearing fault we find a reduction in porosity from the fault breccia 11 7 total and 6 2 connected to the main fault plane 9 total and 3 5 connected with both domains showing higher porosity compared to the protolith 6 8 total and 1 1 connected with increasing confining pressure p wave velocity evolves from 4 5 km s to 5 9 km s in the fault breccia is constant at 5 9 km s approaching the fault plane and is low 4 9 km s in clay rich fault domains we find that while the fault breccia shows pressure sensitive behaviour a reduction in permeability from 2 10 16 m2 to 2 10 17 m2 the cemented cataclasite close to the fault plane is characterized by pressure independent behaviour permeability 4 10 17 m2 our results indicate that the deformation processes occurring within the different fault structural domains influence the physical and transport properties of the fault zone in situ vp profiles match well the laboratory measurements demonstrating that laboratory data are valuable for implications at larger scale combining the experimental values of elastic moduli and frictional properties it results that at shallow crustal levels m 1 earthquakes are less favoured in agreement with earthquake depth distribution during the l aquila 2009 seismic sequence that occurred on carbonates

hydroquakes central apennines italy towards a hydrogeochemical monitoring network for seismic precursors and the hydro seismo sensitivity of boron abstract hydrogeochemical changes before mw 5 0 earthquakes are hoped to be applicable as seismic precursors it is now necessary to pass from single experiences to structured networks systematically monitoring large seismic areas for long periods our aim is to provide a pilot methodological experience for how such networks could be realized and the types of results they could deliver we present the method and some initial results to document the method s applicability in 2017 we started the hydroquakes project in seismically active central italy with the sulmona and matese areas selected as the two monitoring nodes each node includes 5 6 monitored springs and for each spring we performed laboratory analyses of major and trace elements and some isotopes we installed in situ probes for continuous monitoring between december 2017 and january 2020 the most energetic earthquakes were three events with mw of 3 9 4 1 and 4 4 they were not preceded by significant hydrogeochemical anomalies except for the mw 4 1 event despite its low mw this earthquake occurred over a large normal fault at a great depth in the crust 17 km and was preceded by weak but detectable hydrogeochemical anomalies of boron and 11b that were similar but milder than the hydrogeochemical anomalies before the 2016 mw 6 0 earthquake in the central apennines this and previous evidence show the b and 11b hydro seismo sensitivity and indicates that pre seismic hydrogeochemical anomalies could arise mostly before mw 5 0 earthquakes with weak exceptions occurring in specific conditions such as long and deep faults

detecting young slow slipping active faults by geologic and multidisciplinary high resolution geophysical investigations a case study from the apennine seismic belt italy 1 the southern apennines range of italy presents significant challenges for active fault detection due to the complex structural setting inherited from previous contractional tectonics coupled to very recent middle pleistocene onset and slow slip rates of active normal faults as shown by the irpinia fault source of a m6 9 earthquake in 1980 major faults might have small cumulative deformation and subtle geomorphic expression a multidisciplinary study including morphological tectonic paleoseismological and geophysical investigations has been carried out across the extensional monte aquila fault a poorly known structure that similarly to the irpinia fault runs across a ridge and is weakly expressed at the surface by small scarps warps the joint application of shallow reflection profiling seismic and electrical resistivity tomography and physical logging of cored sediments has proved crucial for proper fault detection because performance of each technique was markedly different and very dependent on local geologic conditions geophysical data clearly 1 image a fault zone beneath suspected warps 2 constrain the cumulative vertical slip to only 25 30 m 3 delineate colluvial packages suggesting coseismic surface faulting episodes paleoseismological investigations document at least three deformation events during the very late pleistocene 20 ka and holocene the clue to surface rupturing episodes together with the fault dimension inferred by geological mapping and microseismicity distribution suggest a seismogenic potential of m6 3 our study provides the second documentation of a major active fault in southern italy that as the irpinia fault does not bound a large intermontane basin but it is nested within the mountain range weakly modifying the landscape this demonstrates that standard geomorphological approaches are insufficient to define a proper framework of active faults in this region more in general our applications have wide methodological implications for shallow imaging in complex terrains because they clearly illustrate the benefits of combining electrical resistivity and seismic techniques the proposed multidisciplinary methodology can be effective in regions characterized by young and or slow slipping active faults

mineralogical study of salt efflorescences on soils of the jequetepeque valley northern peru abstract the mineralogical composition and fabric of salt efflorescences from five localities in the jequetepeque valley northern peru were studied most information is derived from the study of thin sections supplemented by chemical data xrd analyses and sem observations three mineral assemblages are distinguished halite trona thenardite halite trona thenardite burkeite pirssonite and halite thenardite eugsterite the habit of the various mineral species and the relations among different components are described for each crust and some tentative explanations are offered for certain features that were observed it is concluded that thin sections can be a powerful tool for the interpretation of the information and diagenesis of salt minerals in soil efflorescences

assessment of vertical contamination of cd pb and zn in soils around a former ore smelter in wallonia belgium concentrations of trace elements cd co cr cu ni pb and zn and major elements ca mg k fe al and mn as well as phkcl and total organic carbon toc were measured on 22 profiles located in a 3 km radius of a former ore treatment plant in wallonia belgium the enrichment factor ef vertical impoverishment factor vif and availability ratio ar were used as diagnostic tools of contamination and migration of cd pb and zn in profiles the data revealed that the soil profiles are significantly contaminated the ranges of efs for cd 17 3570 pb 1 2883 and zn 2 309 are very broad with the higher ef in the topsoil of the profiles vifs of subhorizons are rarely above 1 in the few cases with vif 1 the main factor explaining is the soil type in particular colluvic regosols luvisols and cambisols with shale load cd pb and zn ars are strongly correlated with toc and to a lesser extent with phkcl pb and zn ars are influenced by soil type while land use only has an effect on zn ar the cd availability is independent of these two factors the contents of trace elements measured in soil profiles are very high especially in topsoil at present the cd pb and zn vertical distribution shows a low migration from topsoil to deeper levels however we must not discount the hazard of a future potential transfer

genesis and evolution of gypsum tumuli tumuli are hollow subcircular domes of the most superficial stratum of gypsum principally found in outcrops of macrocrystalline gypsum they vary from a few centimetres to several metres in diameter and reach maximum heights of a little more than 1 m the relationships between the morphostatistical parameters that define these formations are h r 3 and e r 9 where h is the elevation of the raised layer e its thickness and r the mean radius their genesis has caused some controversy over the involvement of phenomena such as hydration of anhydrite or tectonic processes capable of explaining this folding this paper shows their genesis linked to the dissolution of macrocrystalline gypsum and reprecipitation of microcrystalline gypsum within the same gypsiferous layer it has been calculated that to reach the theoretical saturation within the few centimetres thickness of the cap of the tumulus water infiltration velocities are required of between 0 002 cm s 1 for an uplifted stratum of 2 cm thickness and 0 03 cm s 1 for 30 cm thickness these velocities imply the existence of very slow rates of infiltration and or capillary movement of water within the gypsiferous layer the secondary microcrystalline gypsum is precipitated in the intercrystalline and intracrystalline voids of the gypsum crystals producing an increase in porosity and associated volume that causes the doming of the gypsiferous layer the development of tumuli is a cyclic process which is favoured by a sequence of short wet and dry intervals which in turn facilitate the almost simultaneous processes of dissolution and precipitation these conditions predominate in arid and semiarid climates where intense evaporation can occur suddenly following sporadic infiltration copyright 1999 john wiley sons ltd

local pattern of stress field and seismogenic sources in the pergola melandro basin and the agri valley southern italy summary our study area is a ca 50 km long section of the central southern apennines tectonic belt that includes the pergola melandro basin pm and the agri valley av this region is located between the areas affected by the 1980 ms 6 9 irpinia and the 1857 m 7 0 val d agri earthquakes and is characterized by rare historical events and very low and sparse background seismicity in this study we provide new seismological and geophysical information to identify the characteristics of the seismotectonics in the area as the prevailing faulting mechanism and the fit of local to regional stress field these data concern focal mechanisms from waveform modelling and p wave polarities analyses of borehole breakouts and detailed investigation of two seismic sequences all the data cover a significantly broad range of magnitudes and depths and suggest that no important local variation in stress orientation seems to affect this area which shows a ne sw direction of extension consistent with that regionally observed in southern italy such local homogeneity in the stress field pattern is peculiar to the study area the variations of orientation and or type of stress observed in the northern apennines or less than only 100 km toward the northwest within the same tectonic belt are absent here furthermore there is a suggestion for a northeastward sense of dip of the seismogenic faults in the region an interesting constraint to the characterization of seismic sources

indicators of faulting events and periods of quiescence in desert alluvial fans the main objective of the present paper is to present an integrated approach to the study of faulting stages in coarse alluvial deposits the study site is the alluvial fan of nahal shehoret presently under an extremely arid regime the exposure of fault scarps on the fan surfaces enables the identification of several geomorphic indicators employed in analysing and separating faulting events and periods of quiescence a the nature of fault scarp topography b soil catenary development on fault scarps c buried paleosols in alluvial deposits d colluvial bodies e rotated clasts along fault planes these indicators enable us to determine at all sites studied the total amount of displacement to separate faulting events and the amount of their displacement per event and to evaluate scarp stability and the duration of periods of tectonic quiescence

deep injection and closely monitored induced seismicity at paradox valley colorado the u s bureau of reclamation s paradox valley unit pvu extracts aquifer brine from nine shallow wells along the dolores river paradox valley in southwestern colorado and after treating high pressure injects the brine 4 3 4 8 km below the surface pvu injects at rates between 800 and 1300 l min since 1991 pvu has emplaced over 4 106 m3 of fluid and induced more than 4000 surface recorded seismic events the events are recorded on the local 15 station paradox valley seismic network the induced seismicity at paradox separates into two distinct source zones a principle zone 95 of the events asymmetrically surrounding the injection well to a maximum radial distance of 3 km and a secondary ellipsoidal zone 2 5 km long and centered 8 km northwest of the injection well the expansion of these zones has stabilized since mid 1999 about three years after the onset of continuous injection within the principal zone hypocenters align in distinct linear patterns showing at depth stratigraphy and the local wray mesa fracture and fault system the primary faults of the wray mesa system are aseismic striking subparallel to the inferred maximum principal stress direction with one or more faults probably acting as fluid conduits to the secondary seismic zone individual seismic events in both zones do not discernibly correlate with short term injection parameters however a 0 5 km2 region immediately northwest of the injection well responds to long term large scale changes in injection rate and the surpassing of a threshold injection pressure focal mechanisms of the induced events are consistent with simple double couple strike slip moments and subhorizontal extension to the northeast in addition the fault planes are consistent with principal stress directions determined from borehole breakouts more than 99 9 of the pvu seismicity is below human detection m 2 5 however approximately 15 events have been felt locally with the largest being a magnitude m 4 3 because of the m 4 3 and two earlier felt m 3 5 events and injection economics pvu changed injection strategies three times since 1996 these changes reduced seismicity from 1100 events year to as low as 60 events year

impact of quarrying gypsum in a semidesert karstic area sorbas se spain the messinian gypsum of sorbas is intensively karstified with hundreds of dolines and numerous highly unusual exo and endokarstic forms amongst these the tumuli are especially spectacular as are the large caverns adorned with numerous speleothems some of which have not been described anywhere else in the world the extraction of the gypsum has impacted practically all the elements of the environment landscape water soil subsoil flora fauna etc and in particular all of the karstic forms in addition to endangering the caves and the natural treasures that they contain it affects the surface waters markedly modifying the hydrographic network groundwaters which now occur in the bottom of a quarry are also affected

stress aligned cracks in the upper crust of the val d agri region as revealed by shear wave splitting summary shear wave splitting is measured at 19 seismic stations of a temporary network deployed in the val d agri area to record low magnitude seismic activity the splitting results suggest the presence of an anisotropic layer between the surface and 15 km depth i e above the hypocentres the dominant fast polarization direction strikes nw se parallel to the apennines orogen and is approximately parallel to the maximum horizontal stress in the region as well as to major normal faults bordering the val d agri basin the size of the normalized delay times in the study region is about 0 01 s km 1 suggesting 4 5 per cent shear wave velocity anisotropy swva on the south western flank of the basin where most of the seismicity occurs we found larger values of normalized delay times between 0 017 and 0 02 s km 1 these high values suggest a 10 per cent of swva these parameters agree with an interpretation of seismic anisotropy in terms of the extensive dilatancy anisotropy eda model that considers the rock volume pervaded by fluid saturated microcracks aligned by the active stress field anisotropic parameters are consistent with borehole image logs from deep exploration wells in the val d agri oil field that detect pervasive fluid saturated microcracks striking nw se parallel to the maximum horizontal stress in the carbonatic reservoir however we cannot rule out the contribution of aligned macroscopic fractures because the main quaternary normal faults are parallel to the maximum horizontal stress the strong anisotropy and the seismicity concentration testify for active deformation along the sw flank of the basin

geological and environmental implications of the evaporite karst in spain in spain evaporite outcrops cover approximately 7 of the total area of the country most of the evaporitic formations are made up of ca sulfates gypsum anhydrite or ca sulfates and halite certain paleogene marine evaporites also contain k mg chlorides and some tertiary continental formations bear substantial amounts of na sulfates in the subsurface glauberite and thenardite mesozoic evaporitic formations commonly wedge out towards the ground surface passing into condensed sequences and dissolution collapse breccias some of these highly porous breccias constitute major regional aquifers in several areas interstratal karstification of the evaporites has given rise to gravitational deformations such as basin structures monoclines and collapse structures covering several square kilometers that record a cumulative subsidence in excess of 200 m teruel and calatayud grabens a widespread consequence of evaporite dissolution processes in spain is the hydrochemical degradation of surface waters some of the largest and most outstanding lake systems from an environmental perspective occur in karstic depressions developed in evaporitic formations fuente de piedra gallocanta bujaraloz and banolas lakes sinkhole activity is a major geohazard in several evaporite karst areas the sinkhole risk has a particularly high impact in sectors where tertiary evaporites are overlain by quaternary alluvial aquifers calatayud zaragoza and madrid areas some of the detrimental effects of subsidence include severe damage to historical monuments calatayud the demolition of a whole village puilatos or the derailment of a freight train zaragoza area the deepest gypsum caves are found in triassic diapiric structures el sumidor cave 210 m deep and the longest ones are developed in horizontally lying neogene sequences sorbas caves and estremera maze cave the cardona diapir hosts salt caves up to 4 300 m long whose genesis is related to flooding of mine galleries caused by the interception of a phreatic conduit the main anthropogenic impacts on the endokarstic systems are related to the disposal of wastewaters and the destruction of caves by quarrying the fluvial valleys that cross tertiary evaporitic outcrops commonly show peculiar geological characteristics related to dissolution induced synsedimentary subsidence phenomena 1 thickened alluvium filling dissolution basins up to several tens of kilometers long and more than 100 m deep the largest thickenings are found in areas where the bedrock contains halite and glauberite 2 superimposed alluvial units locally bounded by angular unconformities 3 abundant deformational structures and paleosinkholes related to the rockhead and or interstratal karstification of the substratum these fluvial valleys typically are flanked by a prominent gypsum escarpment rock falls favored by the dissolutional enlargement of joints derived from these scarps are the type of mass movement which has caused the highest number of casualties in spain

fluid injection induced seismicity reveals a ne dipping fault in the southeastern sector of the high agri valley southern italy on 2 june 2006 the wastewater produced during the oil and gas field exploitation in high agri valley southern italy started to be managed by disposal through pumping the fluids back into the subsurface at the costa molina 2 cm2 injection well located in the southeastern sector of the valley the onset of microearthquakes ml 2 after 4 days at about 1 3 km sw of cm2 well suggests fluid injection induced seismicity by the diffusion of pore pressure moreover the space time evolution of 196 high resolution relocated events reveals a previously unmapped ne dipping fault we investigate the physical processes related to the fluid injection induced seismicity and delineate the previously unmapped fault by jointly analyzing seismicity data geological observations fluid injection data the stratigraphic log of the cm2 well and the electrical resistivity tomography survey carried out in the study area

high pore fluid pressures at bhuj inferred from 90 flips in shear wave polarizations summary shear wave splitting above local earthquakes in the aftershock zone of the 2001 m w7 6 bhuj earthquake display a spatial variation of anisotropy related to crack orientation at most seismic stations the fast polarization directions are approximately nne ssw parallel to the inferred directions of maximum horizontal stress suggesting the dilatancy induced anisotropy resulting from approximately stress aligned parallel vertical microcracks in contrast the fast polarization directions at station samkhyali skl very close to the epicentre of the main shock are fault parallel approximately ew and almost orthogonal to the stress aligned polarizations elsewhere ape modelling and observations elsewhere suggest that these are 90 flips in shearwave polarizations caused by propagation through microcracks containing fluids at critically high pore fluid pressures surrounding the seismically active fault plane the presence of high pore fluid pressures on all seismogenic faults also explains the high scatter in shear wave time delays the average path normalized delay time varies from 2 to 4 ms km 1 except at station skl where higher delays of up to 13 ms km 1 are found the large scatter in measured time delays is caused by cracks saturated with high pressure pore fluids these observations can be explained by the presence of both normal stress aligned and 90 flipped shear wave polarizations at bhuj this suggests that the kutch mainland fault is a major tectonic feature

gypsum karst evolution in a diapir a case study pinoso alicante spain gypsum deposits are highly soluble and can undergo rapid weathering especially where water intervenes though certain human activities can accelerate the karstification processes an example of karst formed in gypsum at pinoso alicante spain is analysed to show how human activity has impacted on its evolution the karst here is associated with a huge diapir in the triassic terrain that boasts of a large number of highly unusual exokarstic landforms here rock salt has been extracted commercially for over 25 years using solution mining via deep boreholes the brine extracted contains in excess of 300 g l over the whole period more than 12 million tonnes of salt have been extracted using this method after preliminary treatment to remove impurities it travels along a brine pipeline to the coast the enormous volume of the voids generated have probably favoured the acceleration of certain exokarstic and endokarstic processes

using stable isotopes δ 17 o δ 18 o and δd of gypsum hydration water to ascertain the role of water condensation in the formation of subaerial gypsum speleothems abstract we analyzed the stable isotopes 17 o 18 o and d of gypsum hydration water ghw in a variety of speleothems as well as condensation and infiltration waters in five caves of the semiarid gypsum karst of sorbas basin almeria se spain microclimate parameters air temperature relative humidity and effective condensation rate were also monitored over an annual cycle we found that the mother solution from which the majority of gypsum speleothems grow is composed of a mixture of condensation 60 and infiltration water 40 that undergoes evaporation although evaporation of infiltration water alone was thought to be responsible for secondary gypsum precipitation in vadose caves our results suggest that condensation can be a major source of water for the formation of gypsum speleothems the modelled d excess and 17 o trajectories of water during the evaporative process confirm that the majority of speleothems precipitate from a mixture of condensation and infiltration water under relative humidity of 75 85 similar to that measured in the cave atmosphere during winter these findings have important implications for future studies of gypsum speleothems as paleoenvironmental archives

rates of geodetic deformation across active faults in southern italy abstract active deformation in southern italy is accommodated by a distributed number of faults with low moderate slip rates outcropping extensional faults and mostly blind transcurrent faults are mapped within a western or axial and an eastern domain respectively we use a combination of continuous 2001 00 2011 84 and episodic 1995 68 2010 79 gnss observations to firstly estimate the geodetic deformation rate on 32 faults geodetic results were successively compared with geological displacement estimates in agreement with seismological and geological information a net spatial segregation emerges between the extensional axial belt and the eastern domain where strike slip faults are geodetically active although uncertainties are at times large average displacement rates show broadly consistent patterns within both domains a longitudinal gradient in extension rate is observed for the axial fault array with two sectors of higher magnitude 0 8 1 7 mm yr for individual faults this result is consistent with geological observations and supports the notion that extension occurs in discrete patches faults of the eastern domain have lower few 0 1 to 1 2 mm yr strike slip rates and an eastward decreasing extensional component but significant geodetic displacement is detected in areas lacking clear evidence of activity few faults with 1 2 mm yr extension rate are locally found in the eastern domain but based on their limited length and on inconsistency with seismology and geology they are considered as due to deep seated gravitational spreading for crustal faults although geodetic slip and moment rates are larger than geological rates the broad trend of long to short term rates is similar indicating the feasibility of geodetic analysis to contribute estimating fault slip rate and testing tectonic models in the region whereas the western domain extension is thought to be controlled by potential energy related to the tyrrhenian moho uplift beneath the apennines strike slip in the east is related to shear on inherited faults within the adriatic crust

active faults and induced seismicity in the val d agri area southern apennines italy summary the nw se trending val d agri extensional basin is one of the regions in italy with the highest seismogenic potential field data do not univocally define which of the fault systems bordering the basin on the two opposite sides is accommodating the active deformation in this study we detect and locate by using an automatic picking procedure almost 2000 low magnitude earthquakes 0 2 ml 2 7 recorded by a dense network during a 13 months long seismic experiment events are mostly located along the southwestern flank of the basin to the south intense swarm type microseismicity defines a major cluster 5 km wide from 1 to 5 km depth to the west a clear alignment of events characterized by normal faulting kinematics defines a ne dipping normal fault between 1 and 6 km depth the upward continuation of this structure 5 km long matches a mapped active normal fault recognized by field and palaeoseismological surveys a temporal correlation found between the intense swarm type microseismicity and the water level changes in the nearby artificial pertusillo lake suggests that this seismicity is reservoir induced

upper crustal structure seismicity and pore pressure variations in an extensional seismic belt through 3 d and 4 d vp and vp vs models the example of the val d agri area southern italy 1 we use local earthquake tomography and background seismicity to investigate static and transient features of the crustal velocity structure in the val d agri southern apennines italy one of the regions in central mediterranean with the highest seismogenic potential the upper crust is dominated by two broad high velocity anticlines of the buried apulia carbonate platform ramping on two parallel high angle thrusts interpreted as preexisting inverted normal faults the deep core of the anticlines consists of very high vp up to 6 9 km s and low vp vs rocks suggesting the involvement of the apulian crystalline basement in the apennine belt these results provide valuable constraints on the apennine belt tectonic evolution supporting a thick skinned interpretation for the pliocene terminal phase of the compressional tectonics the geometry of the val d agri quaternary basin is controlled by these inherited compressive features whereas the presently active extensional tectonics barely reworked the structure we find inconsistency between the structure of the apulia carbonate platform and the location and geometry of the quaternary normal faults mapped at the surface this suggests either the immaturity of the normal faults or their secondary role in accommodating the extension we observe spatiotemporal 4 d changes of vp and vp vs models defining transient variations of pore fluid pressure in the upper crust a strong change in the vp vs ratio heralds a raise in the seismicity rate that can be related to large water level changes in a nearby artificial lake this evidence is consistent with a mechanism of reservoir induced seismicity by fluid pressure increase and pore pressure diffusion the 4 d velocity variations are confined in the shallow portion of the upper crust 3 6 km depth where fluids are stored in a highly fractured medium pore pressure fluctuations can affect the strength of fault segments favoring seismicity rate changes along the active faults and possibly promoting large future earthquakes

were the may 2012 emilia romagna earthquakes induced a coupled flow geomechanics modeling assessment seismicity induced by fluid injection and withdrawal has emerged as a central element of the scientific discussion around subsurface technologies that tap into water and energy resources here we present the application of coupled flow geomechanics simulation technology to the post mortem analysis of a sequence of damaging earthquakes mw 6 0 and 5 8 in may 2012 near the cavone oil field in northern italy this sequence raised the question of whether these earthquakes might have been triggered by activities due to oil and gas production our analysis strongly suggests that the combined effects of fluid production and injection from the cavone field were not a driver for the observed seismicity more generally our study illustrates that computational modeling of coupled flow and geomechanics permits the integration of geologic seismotectonic well log fluid pressure and flow rate and geodetic data and provides a promising approach for assessing and managing hazards associated with induced seismicity

morphology and micro fabrics of weathering features on gyprock exposures in a semiarid environment ebro tertiary basin ne spain abstract gyprock is a common rock in evaporitic formations which have a wide distribution across all continents however outcrops of gyprock are rather limited occurring mainly in low rainfall areas i e southwest of usa italy spain gyprock is one of the most common lithology in the ebro tertiary basin here semiarid conditions propitiate the development of specific weathering processes and landforms with significant implications for understanding the genesis of soils and the geomorphological evolution of these areas gypsum crystallization within the pores and fissures of gyprock close to the surface leads to volume increase and pressures with the consequent weathering of this rock as a result considerable porosity develops producing peculiar morphologies on gyprock outcrops domes and decimetre scale blisters specific microscopic features voids with plain walls horse shoe pores and serrated pores as well as microscopic fabrics grating fabric skeletal fabric fan fabric and botryoidal fabric this paper presents a morphological characterization of the material forming the various types of weathering features from microscopic to mesoscopic scale the macromorphology and micromorphology of those features were used to interpret their genesis

solution and recrystallisation processes and associated landforms in gypsum outcrops of sicily abstract four small areas of messinian upper miocene age gypsum outcropping in western sicily are described messinian age evaporites are found in sicily over a 1000 km 2 area here gypsum outcrops extensively as a consequence of soil erosion induced by human impact geomorphological maps show how the rocky surfaces are characterized by a wide range of forms there are large medium small and microsized forms which can be identified as belonging to different morphotypes the morphotypes can be classified into two main categories those that originated by solution and those that originated through recrystallisation four areas illustrated by geomorphological maps were specifically chosen to describe a type of medium sized form dome like hills these medium sized forms are covered by a mosaic of smaller forms related to both the previous categories different types of karren and of expansion forms the types of karren can be explained as the results of the solution process under different hydro dynamical behaviour the dome like hills and other related expansion forms are more difficult to understand these expansion forms can be explained by the same process that leads to the development of gypsum tumuli the outcrops of gypsum lacking soil cover and influenced by alternating seasonal water conditions of surplus and deficit are affected by both solution and recrystallisation processes during the wet season the water soaks into the rocky mass filling all the fissures and pores of the outer rocky layer from a few centimetres to some metres below the surface during the dry season there is a capillary upward motion of the water solution near the surface gypsum precipitates from the oversaturated solution increasing the crystal size or forming new crystals in this way during the dry season there is a pressure increase in the outer gypsum layers which is responsible for the development of a gypsum weathering crust and characterised by many different forms such as gypsum tumuli pressure ridges pressure humps and other related small forms the crust may also lead to the development of mega tumuli and dome like hills from the morphostructural point of view the dome like hills do not seem to be controlled by the strike dip or fissuring of the gypsum beds their evolution seems to be linked to the fact that on most of the dome surfaces the weathering crust is evolving through a nearly isotropic field of stresses resulting in volume increase in the outer gypsum layer