halogen bearing minerals in syenites and high grade marbles of dronning maud land antarctica monitors of fluid compositional changes during late magmatic fluid rock interaction processes meta sedimentary rocks including marbles and calcsilicates in central dronning maud land cdml in east antarctica experienced a pan african granulite facies metamorphism with peak metamorphic conditions around 830 20 c at 6 8 0 5 kbar which was accompanied by the post kinematic intrusion of huge amounts of syenitic charnockitic magmas at 4 5 0 7 kbar the marbles and calcsilicates may represent meta evaporites as indicated by the occurrence of metamorphic gypsum anhydrite and cl rich scapolite that formed in the presence of saline fluids with x nacl in the range 0 15 0 27 the marbles and calcsilicates bear biotite tremolite and or hornblende and humite group minerals clinohumite chondrodite and humite which are inferred to have crystallized at about 650 c and 4 5 kbar the syenitic intrusives contain late magmatic biotite and amphibole formed between 750 and 800 c as well as relictic magmatic fayalite orthopyroxene and clinopyroxene two syenite and two calcsilicate samples contain fluorite corona textures in the marbles and calcsilicates suggest very low fluid rock ratios during the formation of the retrograde 650 c assemblages biotite in all but two syenite samples crystallized at log f h 2 o f hf ratios of 2 9 0 4 while in the calcsilicates both biotite and humite group minerals indicate generally higher log f h 2 o f hf values of up to 5 2 a few samples though overlap with the syenite values log f h 2 o f hcl derived from biotite covers the range 0 5 2 6 in all rock types within a single sample the calculated values for both parameters vary typically by 0 1 to 0 8 log units water and halogen acid fugacities calculated from biotite olivine orthopyroxene feldspar quartz equilibria and the above fugacity ratios are 1510 2790 bars for h2o 1 3 5 3 bars for hf and 7 600 bars for hcl the results are interpreted to reflect the reaction of relatively homogeneous magmatic fluids in terms of log f h 2 o f hf derived from the late magmatic stages of the syenites with both earlier crystallized still hotter parts of the syenites and with adjacent country rocks during down temperature fluid flow fluorine is successively removed from the fluid and incorporated into f bearing minerals close to the syenite into metamorphic fluorite in the course of this process log f h 2 o f hf increases significantly chlorine preferably partitions into the fluid and hence log f h 2 o f hcl does not change markedly during fluid rock interaction

applying the multiple inverse method to the analysis of earthquake focal mechanism data new insights into the active stress field of italy and surrounding regions abstract in order to obtain new insights into the active tectonic setting of the italian territory and surrounding regions the multiple inverse method mim has been applied to the analysis of fault plane solutions from more than 700 earthquakes with m w 4 the active stress field in the top 40 km of the lithosphere has been defined for four 10 km thick layers each including 810 square cells of 1 5 side the obtained stress field maps point out that most of the upper crustal seismicity of the western and central alps is controlled by a strike slip regime which is dominant also in part of the dinarides albanides and hellenides and in a large sector encompassing eastern sicily and the malta area to the eastern tunisia offshore on the other hand the well known extensional belt occurring in the interior of the apennines appears to extend well beyond the backbone of italy potentially reaching the outer foothills of the northern marche region while the adjacent adria block extending to the eastern po plain and the outer dinarides sticks out as a major area characterised by dominant thrust faulting in the upper crust a similar regime characterises also a large sector of the western tyrrhenian sea from ne tunisia through western sicily and the west coast of sardinia to the provence coast besides lateral variations our analysis also points out a significant vertical heterogeneity of the stress field the deeper levels 20 to 40 km investigated in this study being characterised by dominant horizontal maximum compression even in areas of upper crustal extension the application of the mim to a large seismological dataset providing basic information for the compilation of active stress maps contributes to a better understanding of active tectonic processes and may be used for improving seismotectonic zoning and reservoir management

three dimensional seismic tomography from p wave and s wave microearthquake travel times and rock physics characterization of the campi flegrei caldera 1 the campi flegrei cf caldera experiences dramatic ground deformations unsurpassed anywhere in the world the source responsible for this phenomenon is still debated with the aim of exploring the structure of the caldera as well as the role of hydrothermal fluids on velocity changes a multidisciplinary approach dealing with three dimensional delay time tomography and rock physics characterization has been followed selected seismic data were modeled by using a tomographic method based on an accurate finite difference travel time computation which simultaneously inverts p wave and s wave first arrival times for both velocity model parameters and hypocenter locations the retrieved p wave and s wave velocity images as well as the deduced v p v s images were interpreted by using experimental measurements of rock physical properties on cf samples to take into account steam water phase transition mechanisms affecting p wave and s wave velocities also modeling of petrophysical properties for site relevant rocks constrains the role of overpressured fluids on velocity a flat and low v p v s anomaly lies at 4 km depth under the city of pozzuoli earthquakes are located at the top of this anomaly this anomaly implies the presence of fractured overpressured gas bearing formations and excludes the presence of melted rocks at shallow depth a high v p v s anomaly located at 1 km suggests the presence of rocks containing fluids in the liquid phase finally maps of the v p v s product show a high v p v s horseshoe shaped anomaly located at 2 km depth it is consistent with gravity data and well data and might constitute the on land remainder of the caldera rim detected below sea level by tomography using active source seismic data

pore pressure migration along a normal fault system resolved by time repeated seismic tomography in this study we outline the space and time variations of body wave velocities during one of the best documented series of normal faulting earthquakes the 1997 umbria marche sequence in central italy we show the first ever observations of rock fracturing and fluid overpressure propagation along a fault system by using space time resolved variations of vp vs anomalies four dimensional variations that accompany earthquake migration and precede large aftershocks the vp vs increase observed before the mid october earthquakes was related to a pore pressure increase on fluid filled cracks in the volume around the fault we also document that such variations are measurable only by using s and p wave arrival times

hydrogeochemistry of the campania region in southern italy abstract a geochemical study of thermal springs cold springs stream waters and natural gas emissions has been carried out in the campania region of southern italy this region hosts four quaternary volcanic areas and thermal springs and gas emissions occur in three of them most thermal springs discharge na cl composition waters of connate origin derived from post orogenic volcanic and sedimentary formations although high enthalpy systems are present in two of the four volcanic areas there appear to be no magmatic contributions to the thermal springs solute geothermometers are unreliable as spring waters are strongly affected by mixing with shallow brines before discharging thermal springs and gas emissions also occur in non volcanic areas where an extensive carbonate unit acts as a regional aquifer for cold low salinity bicarbonate waters thermal features in these areas occur in fractured zones associated with active faults their compositions are determined only by the type of rock encountered by solutions before surface discharge as in other areas of north central italy the widespread occurrence of hot and cold co2 rich springs and gas emissions in both volcanic and non volcanic zones suggests a deep origin for the co2

a three dimensional image of shallow subduction crustal structure of the raukumara peninsula new zealand summary earthquake arrival time data from a 36 station deployment of portable seismographs on the raukumara peninsula have been used to determine the 3 d vp and vp vs structure of this region of shallow subduction a series of inversions have been performed starting with an inversion for 1 d structure then 2 d and finally 3 d this procedure ensures a smooth regional model in places of low resolution the subducted plate is imaged as a northwest dipping feature with vp consistently greater than 8 5 km s 1 in the uppermost mantle of the plate structure in the overlying plate changes significantly along strike in the northeast there is an extensive low velocity zone in the lower crust underlying the most rapidly rising part of the raukumara range it is bounded on its arcward side by an upwarp of high velocity a viable explanation for the low velocity zone is that it represents an accumulation of underplated subducted sediment while serpentinization of the uppermost mantle may be responsible for the adjacent high velocity region the low velocity zone decreases and the adjacent high velocity region is less extensive in the southwest this change is interpreted to be related to a change in the thickness of the crust of the overlying plate in the northeast the crust is thinner and subducted sediment ponds against relatively strong uppermost mantle while in the southwest the crust is thicker and the relatively weak lower crust allows sediment subduction to greater depths a narrow zone of high vp vs parallels the shallow part of the plate interface this suggests elevated fluid pressures with the distribution of earthquakes about this zone further suggesting that these pressures may be close to lithostatic the plate interface at 20 km depth beneath the raukumara peninsula may thus be a closed system for fluid flow similar to that

tectonic burial and young 10 ma exhumation in the southern apennines fold and thrust belt italy in the southern apennines fold and thrust belt thermal indicators record exhumation of sedimentary units from depths locally in excess of 5 km the thrust belt is made of allochthonous sedimentary units that overlie a 6 8 km thick carbonate footwall succession the latter continuous with the foreland apulian platform is deformed by reverse faults involving the underlying basement therefore a switch from thin skinned to thick skinned thrusting occurred as the apulian platform carbonates and the underlying thick continental lithosphere were deformed during the latest shortening stages apatite fission track data showing cooling ages ranging between 9 2 1 0 and 1 5 0 8 ma indicate that exhumation marks these late tectonic stages probably initiating with the buttressing of the allochthonous wedge against the western margin of the apulian platform pliocene pleistocene foreland advancing of the allochthonous units exceeds the total amount of slip that based on cross section balancing and restoration could be transferred to the base of the allochthon from the underlying thick skinned structures this suggests that emplacement of the allochthon above the western portion of the apulian platform carbonates was followed by gravitational readjustments within the allochthonous wedge coeval and partly associated with thick skinned shortening at depth the related denudation processes are interpreted to have played a primary role in tectonic exhumation

applying a three dimensional velocity model waveform cross correlation and cluster analysis to locate southern california seismicity from 1981 to 2005 we compute high precision earthquake locations using southern california pick and waveform data from 1981 to 2005 our latest results are significantly improved compared to our previous catalog by the following 1 we locate events with respect to a new crustal p and s velocity model using three dimensional ray tracing 2 we examine six more years of waveform data and compute cross correlation results for many more pairs than our last analysis and 3 we compute locations within similar event clusters using a new method that applies a robust fitting method to obtain the best locations satisfying all the differential time constraints from the waveform cross correlation these results build on the relocated catalogs of hauksson and shearer 2005 and shearer et al 2005 and provide additional insight regarding the fine scale fault structure in southern california and the relationship between the san andreas fault saf and nearby seismicity in particular we present results for two regions in which the seismicity near the southern saf seems to align on dipping faults

magnetite lamellae in olivine and clinohumite from dabie uhp ultramafic rocks central china ultrahigh pressure uhp minerals of the maowu mafic ultramafic complex in the dabieshan east central china exhibit many exsolution textures magnetite lamellae are common in olivines and ti clinohumites from harzburgite and garnet pyroxenite monazite ce lamellae occur in apatites from the garnet pyroxenite independent p t estimates suggest that these ultramafic rocks formed at p 5 gpa and t 700 50 c the lamellae bearing minerals are believed to preserve an earlier higher p t record prior to exsolution compositions and unit cell parameters of the magnetite and host olivine and intergrowth relations were determined using a newly developed x ray diffraction microprobe technique employing synchrotron radiation the host olivine and magnetite lamellae bear a topotaxial relation with 220 mag 200 ol 111 mag 3 3 1 ol 11 1 mag 331 ol 242 mag 2 2 0 ol the recalculated composition of primary olivine may contain up to 1 5 wt fe 2o3 four hypotheses may explain the observed intergrowths of oriented magnetite lamellae in olivine 1 oxidation of olivine 2 decomposition of fe 3 bearing olivine formed at 6 gpa 3 exsolution of a spinel wadsleyite solid solution fe 3o4 fe mg 2sio4 during decompression and 4 breakdown of phase a mg7si2 oh 6 enstatite the third hypothesis appears to be the most likely inasmuch as no additional silicate phase occurs as associated inclusions in the olivine host however the actual mechanism for exsolution of magnetite from olivine remains to be studied experimentally

the 7 may 2001 induced seismic event in the ekofisk oil field north sea 1 a moderate size seismic event on 7 may 2001 was strongly felt on platforms in the ekofisk oil field in the southern north sea but did not cause damage to platforms or wells we combined near and far field observations to develop a consistent source model and to determine whether the event was induced seismic data placed the epicenter inside the ekofisk field and suggested a shallow source depth based on spectral and moment tensor analysis gps data from the ekofisk platforms displayed permanent vertical and horizontal movement due to the event a topographic bulge in the sea bottom revealed by differential bathymetry data and overpressure in the overburden in the northeastern part of the field detected only after the event had been caused by unintentional water injection that started in 1999 the injection pressure and rate were sufficient to raise the overburden pressure gauge and compaction data ruled out that the event occurred at reservoir level which was further supported by unaffected production rates and absence of well failure we therefore conclude that the event occurred in the overburden at less than 3 km depth initially this appeared unlikely on account of very low shear strength of the overburden clay rich shale and mud rocks the seismic event was induced owing to stress changes caused by water injection the event possibly initiated on the northern flank of the field near the water injector and may have involved flexure of the overburden into the depression bowl in the rest of the field moment tensor analysis is consistent with a pure double couple source we suggest that slip occurred on the near horizontal rather than along the near vertical nodal plane stress drop was low and owing to the low overburden shear strength the event released less energy than a typical stress drop event with similar source dimensions

fault plane processes and mesoscopic structure of a strong type seismogenic fault in tonalites adamello batholith southern alps abstract the gole larghe fault is an exhumed paleoseismic fault crosscutting the adamello tonalites italian southern alps ambient conditions of faulting were 9 11 km in depth and 250 300 c in the study area the fault accommodates 1100 m of dextral strike slip over a fault thickness of 550 m displacement is partitioned into three hierarchically different sets of discrete subparallel cataclastic horizons faults1 2 3 fault displacement is in the range of few centimeters faults3 to a maximum of a few tens of meters in major faults1 faults1 2 nucleated on pre existing joints whereas faults3 are newly generated fractures produced during slip along faults1 2 each fault within the gole larghe fault records the same evolution with development of indurated cataclasites precursory to pseudotachylyte production pseudotachylytes are usually generated at the host rock cataclasite boundary and within cataclasites the mean clast size decreases getting closer to pseudotachylyte fault veins pseudotachylytes and cataclasites have a similar chemical composition which is enriched in loss on ignition k rb ba u and fe3 compared to host rock we envision two models for the evolution of the gole larghe fault in both models synkinematic fluid rock interaction along a fault causes fault hardening by precipitation of abundant k feldspar epidote and minor chlorite in the cataclasite matrix conducive to final production of pseudotachylyte in the first model induration occurs progressively by differential precipitation related to fabric evolution in cataclasites in the second model induration occurs abruptly dependent on the development of full connectivity within the fault network and to fluid reservoir whatever the model the gole larghe fault represents a strong fault where hardening processes resulted in a low displacement fault thickness ratio and contrast with many mature weak faults where localized repeated seismic slip along the same weak horizons yields high displacement fault thickness ratios

fault mechanism of the 40 seconds subevent of the 1980 irpinia southern italy earthquake from levelling data a model for the 40 s subevent of the 1980 irpinia earthquake is obtained from levelling data an inverse method has been used to compute fault parameters based on the computation of the probability density on strike and dip angles and midpoint fault location the highest probability model consists of a fault almost parallel to the one associated to the first subevent this fault dips about 80 sw forming a small graben like structure with the main fault fault strike and dip parameters appear well constrained by levelling data to within 10 at 95 confidence level it is noteworthy that seismological and accelerometric data were not able to well constrain the fracture mechanism of this subevent which was the most controversial one in literature crosson et al 1986 westaway 1987 crosson et al 1987 westaway and jackson 1987 bernard and zollo 1989

a new seismic tomography of aigion area gulf of corinth greece from the 1991 data set summary an ew three dimensional delay traveltime tomography is performed to image the intermediate structure of the western gulf of corinth a large data set collected in 1991 during a two month passive tomographic experiment has been reanalysed for the reconstruction of detailed vp and vs images an improved tomography method based on an accurate traveltime computation is applied to invert simultaneously delayed p and s first arrival traveltimes for both velocity and hypocentre parameters we perform different synthetic tests to analyse the sensitivity of tomography results to the model parametrization and to the starting 1 d model selection the analysis of the retrieved vp and vs models as well as deduced vp vs and vp vs images allows us to interpret and delineate the distribution of lithological variation porosity crack content and fluid saturation in the upper 9 11 km of the crust beneath the gulf the tomographic models image a rather complex crustal structure which is characterized by a vertical change in both velocity features and seismicity distribution we identify a shallower zone of the crust 0 5 km depth in which velocity distributions seem to be controlled by the still active n s extensional regime and a deeper zone 7 11 km depth which matches the seismogenic zone the correlation between this latter and a specific unit of the hellenic mountain structure the pyllite quartzite series allows us to suggest a possible explanation for seismicity concentration in a narrow band at 7 9 km depth finally the occurrence of clusters showing low angle normal fault mechanisms in areas characterized by high vp vs values indicates a possible role of fluids in triggering brittle creep along the identified low angle normal faults

pre transform early miocene extension in western california earliest miocene 20 24 ma faulting and volcanism were widespread in western california including the san joaquin la honda basin coast ranges and transverse ranges evidence for strike slip on faults of this age is lacking their arrangement on a pre san andreas restoration suggests continuity with early miocene extended terranes in eastern california and southwestern arizona deformation was probably not an effect of transform or triple junction migration tectonics because it was synchronous over 300 km of latitude and there is no direct evidence for a transform boundary until late in early miocene time magnetic anomalies in the eastern pacific permit an interpretation that a spreading ridge supplied a still active subduction zone with young oceanic crust until sometime after 20 ma if so extension evidently took place in an arc related setting a transform regime probably formed about 18 ma when most basins underwent episodes of deepening or uplift strike slip faults became active and rotation of the western transverse ranges block began

overpressure detection from compressional and shear wave data by analyzing experimental data we show that in many room dry rocks the poisson s ratio pr decreases with decreasing differential pressure confining minus pore pressure this means that in gas saturated rocks pr decreases with increasing pore pressure we confirm the generality of the observed effect by theoretically reproducing it via effective medium modeling this effect can be used as a new tool for overpressure detection from surface seismic cross well sonic logs and measurements ahead of the drill bit

humite and scapolite bearing assemblages in marbles and calcsilicates of dronning maud land antarctica new data for gondwana reconstructions this study investigates marbles and calcsilicates in central dronning maud land cdml east antarctica the paleogeographic positioning of cdml as part of gondwana is still unclear however rock types mineral assemblages textures and p t conditions observed in this study are remarkably similar to the kerala khondalite belt in india the cdml marbles and calcsilicates experienced a pan african granulite facies metamorphism at c 570 ma and an amphibolite facies retrogression at c 520 ma the highest grade assemblage in marbles is forsterite spinel calcite dolomite in calcsilicates the assemblages are diopside spinel diopside garnet scapolite wollastonite clinopyroxene quartz scapolite anorthite calcite clinopyroxene wollastonite these assemblages constrain the peak metamorphic conditions to 830 20 c 6 8 0 5 kbar and xco2 0 46 during retrogression highly fluoric humite group minerals humite clinohumite chondrodite replaced forsterite and garnet rims formed at the expense of scapolite during reactions with wollastonite calcite or clinopyroxene but without involvement of anorthite metamorphic conditions were about 650 c 4 5 0 7 kbar 0 2 xco2fluid 0 36 and the co existence of garnet clinopyroxene wollastonite and quartz constrains fo2 to fmq 1 5 log units mineral textures indicate a very limited influx of h2o rich fluid during amphibolite facies retrogression and point to significant variations of fluid composition in mm sized areas of the rock gypsum was observed in two samples it probably replaced metamorphic anhydrite which appears to have formed under amphibolite facies conditions the observed extensive anorogenic magmatism anorthosites a type granitoids and the character of metamorphism between 610 and 510 ma suggest that the crustal thermal structure was characterized by a long lived 50 100 ma rise of the crustal geotherm probably caused by magmatic underplating

seismic imaging of a fluid storage in the actively extending apennine mountain belt southern italy a picture of the upper crustal structure of the irpinia active faults system in southern italy was obtained by combining new geological evidences lithological properties and microseismicity distribution p and s wave velocity models indicate high vp vs and low vp vs values suggesting fluid accumulation within a 15 km wide rock volume where intense microseismicity is located the 1980 irpinia ms 6 9 earthquake nucleated within the same fault bounded volume we suggest that concentration of background seismicity is mainly controlled by high pore fluid pressure its increase in fluid filled cracks around major faults leads to earthquakes nucleation seismic pumping along major faults carries fluids through the conduit system represented by the intensely fractured damage zone conversely the cross fault barrier behavior of the low permeability fault core leads to pore fluid pressures building up within the fault bounded block thus producing a positive feedback triggering earthquake nucleation within the volume which behaves as an earthquake reservoir

fluid rock history of granulite facies humite marbles from ambasamudram southern india an extensive humite bearing marble horizon within a supracrustal sequence at ambasamudram southern india was studied using petrological and stable isotopic techniques to define its metamorphic history and fluid characteristics at peak metamorphic temperatures of 775 73 c based on calcite graphite carbon isotope thermometry the mineral assemblages suggest layer by layer control of fluid compositions clinohumite calcite bearing assemblages suggest xco2 0 9 at 790 c and local wollastonite scapolite grossular bearing zones formed at xco2 of c 0 3 retrograde reaction textures such as scapolite quartz symplectites after feldspar and calcite and replacement of dolomite diopside or tremolite dolomite after calcite forsterite or calcite clinohumite are indicative of retrogression under high xco2 conditions calcite preserves late proterozoic carbon and oxygen isotopic signatures and the marble lacks evidence for extensive retrograde fluid infiltration while during prograde metamorphism the possible infiltration of aqueous fluids did not produce significant isotopic resetting isotopic zonation of calcite and graphite grains was likely produced by localized co2 fluid infiltration during retrogression contrary to the widespread occurrence of humite marbles related to retrograde aqueous fluid infiltration the ambasamudram humite marbles record a prograde to peak metamorphic humite formation and retrogression under conditions of low xh2o

fault delineation and regional stress direction from the analysis of background microseismicity in the southern apennines italy abstract the present active faults and stress field acting in the southern apennines italy a structurally complex area characterized by high seismic potential are studied by analyzing the background microseismicity m 3 we used a microearthquake data set consisting of 1312 events that occurred from august 2005 to april 2011 by integrating the data recorded at 42 seismic stations of various networks the refined seismicity locations and focal mechanisms delineate a system of northwest southeast striking normal faults along the apenninic chain and an approximately east west oriented strike slip fault transversely cutting the belt the seismicity along the chain does not occur on a single fault but in a volume delimited by the faults activated during the 1980 irpinia m 6 9 earthquake on subparallel predominantly normal faults results show that the recent low magnitude earthquakes belong to the background seismicity and they are likely generated along the major fault segments activated during the most recent earthquakes suggesting that they are still active today 30 years after the mainshock occurrences the stress inversion from the whole data set suggests that a unique anti apenninic extensional regional stress field could explain the two different faulting styles characterizing the earthquakes that occur along the chain and the east west fault dissecting the belt on the other hand the results obtained by separately inverting the irpinia and the potenza clusters indicate a more complex model that would predict a change from a normal faulting regime acting in the inner sector of the chain to a strike slip regime moving eastward and down depth in the potenza area online material seismicity maps and focal mechanisms

attenuation models qp and qs in three dimensions of the southern california crust inferred fluid saturation at seismogenic depths we analyze high dynamic range waveform spectra to determine t values for both p and s waves from earthquakes in southern california we invert the t values for three dimensional 3 d frequency independent q p and q s regional models of the crust the models have 15 km horizontal grid spacing and an average vertical grid spacing of 4 km down to 22 km depth and extend from the u s mexico border to the coast ranges in the south and sierra nevada in the north in general qp and qs increase rapidly with depth consistent with crustal densities and velocities the 3 d q p and q s models image the major tectonic structures and to a much lesser extent the thermal structure of the southern california crust the near surface low q p and q s zones coincide with major sedimentary basins such as the san bernardino chino san gabriel valley los angeles ventura and santa maria basins and the salton trough in contrast at shallow depths beneath the peninsular ranges southern mojave desert and southern sierras we image high q p and q s zones which correspond to the dense and high velocity rocks of the mountain ranges several clear transition zones of rapidly varying q p and q s coincide with major late quaternary faults and connect regions of high and low q p and q s at midcrustal depths the q p and q s exhibit modest variation in slightly higher and lower qp or qs zones which is consistent with reported crustal reflectivity in general for the southern california crust q s q p is greater than 1 0 suggesting partially fluid saturated crust a few limited regions of q s q p less than 1 0 correspond to areas mostly outside the major sedimentary basins including areas around the san jacinto fault suggesting a larger reduction in the shear modulus compared to the bulk modulus or almost complete fluid saturation

the database of individual seismogenic sources diss version 3 summarizing 20 years of research on italy s earthquake geology abstract this paper describes the main characteristics the evolution and the structure of the database of individual seismogenic sources diss and particularly of its release of early 2007 the database contains the results of the investigations of the active tectonics in italy during the past 20 years the first two sections of this paper document the recent evolution in mapping and archiving italian active fault data in relation to important achievements in the understanding of italian tectonics some of which were spurred by significant earthquakes the central sections describe the current structure of the database the reasons for its assumptions and data categories its current contents its evolution through several years of improvements the last section describes how the current contents of the database correspond with the existing strain and stress data available from focal mechanism borehole breakout and gps data for the whole of italy the database supplies a fresh and unified view of active and seismogenic processes in italy by building on basic physical constraints concerning rates of crustal deformation on the continuity of deformation belts and on the spatial relationships between adjacent faults both at the surface and at depth

the irpinia italy 1980 earthquake detailed analysis of a complex normal faulting a detailed analysis of near source strong motion and leveling data together with the results of teleseismic waveform modeling by westaway and jackson 1987 and aftershock studies by deschamps and king 1984 allows a satisfactory kinematic description of the complex normal faulting associated with the magnitude ms 6 9 november 23 1980 irpinia earthquake southern italy the three main rupture episodes starting at about 0 20 and 40 s are here associated with better constrained source parameters than in previous studies we first evaluated the triggering time for the 11 closest accelerometers by using the well recorded 40 s strong motion phases this gave the absolute time and location of the dominant episodes of faulting the first rupture propagated mainly toward the northwest on a ne dipping normal fault at a mean velocity close to 3 km s for about 20 km and continued 15 km further on smaller subfaults it was associated with surface breakage in the southeastern part the second rupture started from the southeastern end of the first rupture about 18 s after it and propagated about 20 km toward the southeast on a low angle normal fault dipping 20 ne it was associated with secondary faulting on steeper planes reaching the surface the third and last episode at 39 s nucleated near the first hypocenter at shallower depth and the rupture possibly propagated on a 10 to 15 km long normal fault striking se antithetic to the first activated fault a clear correlation appears between the strength of the geological formations and the existence of surface breakage and shallow aftershock activity

fault properties and fluid flow patterns from quaternary faults in the apennines italy the study of quaternary fault zones in the high agri valley southern italy and in the axial zones of the central apennines allowed us to collect information on the permeability structure fluid characteristics and scaling properties of the main fault zones exposed in the area detailed structural mapping allowed us to derive the appropriate values of the fractal dimension characterising different active fault zone patterns and to evaluate the basic parameters needed for assessing the architecture and related permeability structure of the mapped faults scan line and scan area analysis helped in constraining the scaling properties of some of the attributes i e fault zone thickness fracture spacing etc of the main fault zones and in defining their validity range our results suggest that in the apennines i extrapolation of the architectural indices of a fault zone is admissible over three orders of magnitude and ii the composition of the analysed fluid inclusions and related homogenisation temperatures are associated with fault driven fluid circulation from both superficial and deep 4 6 km levels

source parameter scaling and radiation efficiency of microearthquakes along the irpinia fault zone in southern apennines italy we analyzed the p and s wave displacement spectra of 717 microearthquakes in the moment range 4 109 2 1014 n m recorded at the dense networks operating in southern apennines italy and deployed along the 1980 ms 6 9 irpinia earthquake fault zone source attenuation and site parameters are estimated by using a parametric modeling approach which is combined with a multistep nonlinear inversion strategy we found that in the analyzed frequency band an attenuation model with constant q has to be preferred to frequency dependent q models consistent estimates of the median p and s quality factors q p 167 90 296 and q s 226 114 417 are obtained from two different techniques and relatively high values of qs qp median value 1 3 0 8 2 1 are found in the same depth range where high vp vs and a peak in seismicity distribution are observed this is the evidence for a highly fractured partially or completely fluid saturated medium embedding the irpinia fault zone down to crustal depths of 15 20 km a nearly constant stress drop 1 4mpa 0 4 5 0 and apparent stress a 0 1mpa 0 03 0 4 scaling of p and s corner frequencies and seismic energies is observed above a seismic moment value of about 1011 n m the measured radiation efficiency is low sw 0 06 0 030 13 e g the radiated energy is only a small fraction of the whole energy spent by friction and fracture development a large positive dynamic overshoot high dynamic shear strength can be the dominant mechanism controlling the microearthquake fractures along the irpinia fault zone

soil gas distribution in the main coseismic surface rupture zone of the 1980 ms 6 9 irpinia earthquake southern italy soil gas measurements of different gas species with different geochemical behaviors were performed in the area of the pecore plain a 200 m 300 m sized fault bounded extensional basin located in the northern mount marzano massif in the axial belt of the southern apennine chain the pecore plain area was affected by coseismic surface faulting during the ms 6 9 1980 irpinia earthquake the strongest and most destructive seismic event of the last 30 years in southern italy the collected data and their geostatistical analysis provide new insights into the control exerted by active fault segments on deep seated gas migration toward the surface the results define anomalies that are aligned with the nw se trending coseismic rupture of the 1980 earthquake along the western border of the plain as well as along the southern border of the plain where a hidden e w striking fault is inferred geospatial analysis highlights an anisotropic spatial behavior of 222rn along the main nw se trend and of co2 along the e w trend this feature suggests a correlation between the shape and orientation of the anomalies and the barrier conduit behavior of fault zones in the area furthermore our results show that gas migration through brittle deformation zones occurs by advective processes as suggested by the relatively high migration rate needed to obtain anomalies of short lived 222rn in the soil pores

titanian clinohumite in the carbonatites of the jacupiranga complex brazil mineral chemistry and comparison with titanian clinohumite from other environments

tufa and travertines of southern italy deep seated fault related co 2 as the key control in precipitation continental carbonates of quaternary age in southern italy commonly exhibit the facies of calcareous tufa often reported as related to shallow aquifers fed by meteoric waters and to organic processes a close spatial relationship exists between the mappable tufa deposits and major quaternary extensional faults with respect to the ca mg hco3 composition of limestone aquifers springs tufa depositing springs exhibit higher salinity and alkalinity are slightly warmer have lower ph and are enriched in so4 and co2 their d 13 c values are systematically positive and compatible with a deep seated carbon source a clear input of soil derived organic carbon is indicated only for small non mappable tufas deposited by perched springs the dataset indicates that the large tufa deposits owe their origin to a supplementary source of co2 advected by degassing through active faults as a necessary prerequisite for inducing a rise of total dissolved salts and alkalinity meteoric waters that have come from a shallow aquifer are able to precipitate only limited amount of carbonates

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

seismological studies at parkfield i simultaneous inversion for velocity structure and hypocenters using cubic b splines parameterization a model for the 3d p and s wave velocity structure at parkfield has been developed by the systematic inversion of arrival times for microearthquakes and surface vibroseis sources recorded by nearby calnet stations and by the local borehole installed 10 station high resolution seismic network there a modification of the linear b splines model parameterization method of thurber 1983 to a cubic b splines formulation through tests inverting synthetic data sets for the parkfield configuration is found to produce smooth velocity distributions that still retain some small scale features application of the method to 953 p wave and 288 s wave arrivals from 111 microearthquakes and 8 vibroseis locations throughout the study area yields a velocity structure having variable resolution a low velocity zone appears to coincide with the creeping segment of the san andreas fault zone northwest of the 1966 parkfield earthquake epicenter an increase of about 15 per cent in seismic velocities is seen from the northeast to southwest across this segment of the fault zone the higher velocities to the southwest apparently correspond to the granitic basement the contrast across the fault is subdued to the southeast along the 1966 rupture zone a high vp vs ratio of 1 9 is seen in a 2 km wide volume near the location of the 1966 main shock hypocenter presumably the nucleation zone for the expected m 6 parkfield earthquake