paleoseismology along the 1980 surface rupture of the irpinia fault implications for earthquake recurrence in the southern apennines italy the irpinia fault was the source of the ms 6 9 1980 irpinia earthquake and produced the first unequivocal historical surface faulting in italy trenching of the 1980 fault scarp at piano di pecore a flat intermontane basin about 5 km south of the 1980 instrumental epicenter provides the first data on earthquake recurrence intervals slip per event and slip rate on a major normal fault in the southern apennines fault zone the trenches exposed evidence of four pre 1980 paleoearthquakes that occurred during the past 8600 years a best estimate average recurrence interval is 2150 years although the time interval between individual events varies by as much as a factor of 2 each paleo earthquake is similar to the 1980 surface rupture in amount of slip and style of deformation which suggests that the 1980 event is characteristic for the irpinia fault slip per event values average 61 cm the net vertical displacement of 2 12 2 36 m since 8600 cal year b p observed in the trenches gives a vertical slip rate of 0 25 0 35 mm yr a dip slip rate of 0 29 0 40 mm yr and an extension rate of 0 14 0 20 mm yr although fault behavior data are only available for the irpinia fault they provide a starting point for evaluating earthquake recurrence and rates of deformation in southern apennines they suggest that 1 fault specific earthquake recurrence intervals based on the historical seismic record overestimates the occurrence of large magnitude m7 earthquakes and 2 the holocene rate of extension across the apennines is 1 mm yr the 1980 earthquake and the paleoseismologic observations show that repeated and localized surface faulting occurs in southern apennines and leaves subtle but distinct geomorphic evidence that can be detected with detailed and careful investigation

contemporaneous extension and compression in the northern apennines from earthquake fault plane solutions summary the northern apenninic arc belongs to the deformation zones surrounding the adriatic plate which behaves as a rigid block it is a ne verging fold and thrust belt which developed since the miocene with the migration of an extensional compressional pair previous seismological data are roughly in agreement with this deformation picture although the outer compressional front was not clearly defined by the few available solutions in this work we confirm the existence of two adjacent zones of contemporaneous extension and compression in the northern apennines defining the extent of these two zones and their interim1 deformation better than was previously done this is accomplished through the analysis of 125 new focal mechanisms of earthquakes 2 6 md 4 8 recorded by the national network of the lstituto nazionale di geofisica in the period 1988 1995 the two deformation zones are clearly separated and lie very close to each other with a partial overlapping in the emilian tuscan apennines strikeslip events are scattered in most of the study area thrust faulting earthquakes are located in the internal part of the most recently active thrust front middle upper pleistocene there is a general trend of the compressional p axes of thrust fault and strike slip solutions to be perpendicular to the apenninic direction in the external zone while the tensional axes of the normal fault and strike slip solutions in the belt do not show a uniform orientation however clearly evident is the ene direction of extension in the peri tyrrhenian region consistent with the direction of shmln in the quaternary volcanoes of this region inferred from borehole breakouts and microearthquake fault plane solutions we determined the orientation of the stress tensor in the two main deformation zones by inversion of the 125 fault plane solutions determined in this study we found that the external belt is characterized by ne sw compression ol horizontal oriented n45 e while a normal faulting regime with o3 e w oriented is characteristic of the umbria tuscany back arc region

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

orthogonal relation between wavefield polarization and fast s wave direction in the val d agri region an integrating method to investigate rock anisotropy 1 wavefield polarization is investigated using 200 seismograms recorded by a network of 20 stations installed on rock outcrops in the val d agri region that hosts the largest oil fields in the southern apennines italy polarization is assessed both in the frequency and time domains through the individual station horizontal to vertical spectral ratio and covariance matrix analysis respectively we find that most of the stations show a persistent horizontal polarization of waveforms with a ne sw predominant trend this direction is orthogonal to the general trend of quaternary normal faults in the region and to the maximum horizontal stress related to the present extensional regime according to previous studies in other areas such a directional effect is interpreted as due to the presence of fault related fracture fields polarization being orthogonal to their predominant direction a comparison with s wave anisotropy inferred from shear wave splitting indicates an orthogonal relation between horizontal polarization and fast s wave direction this suggests that wavefield polarization and fast velocity direction are effects of the same cause the existence of an anisotropic medium represented by fractured rocks where shear wave velocity is larger in the crack parallel component and compliance is larger perpendicularly to the crack strike the latter is responsible for the observed anisotropic pattern of amplitudes of horizontal ground motion in the study area

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

low latitude zonal and vertical ion drifts seen by de 2 horizontal and vertical ion drift data from the de 2 spacecraft have been used to determine average zonal and vertical plasma flow electric field characteristics in the plus minus 26 degree dip latitude region during a time of high solar activity the data base consists of over 800 equatorial passes horizontal ion drift data were projected along magnetic field lines to the magnetic equator using a dipole model to yield their apex height dependence the average data local time profile for an apex height bin centered at 400 km indicates westward plasma flow from 0600 to 1900 solar local time slt with a maximum westward velocity of 80 m s in the early afternoon there is a sharp change to eastward flow at approximately 1900 hours with an early evening peak of 170 m s a secondary nighttime maximum exists a 0430 slt preceeding the reversal to westward flow this profile is in good agreement with jicamarca radar measurements made under similar solar maximum conditions harmonic analysis indicates a net superrotation which is strongest at lower apex altitudes the diurnal term is dominant but higher order terms through th quatradiurnal are significant vertical ion data taken at low plus minus 5 degree dip latitudes while possessing greatermore scatter generally agree wtih jicamarca values copyright american geophysical union 1989 less

the campania lucania extensional fault system southern italy a suggestion for a uniform model of active extension in the italian apennines 1 by integrating new field data seismic lines interpretation and a critical review of the literature this work highlights a regional array of normal faults in the southern apennines of italy which have been active during the quaternary and are referred to as the campania lucania extensional fault system clefs the clefs consists of three main nw se striking alignments of normal faults which for the first time are considered genetically linked and methodically described in their geometry kinematics and displacement the crop04 seismic profile crossing the central part of the clefs was strictly constrained by detailed geological surveys and reinterpreted to define the downdip trajectory of the major normal faults these latter have been observed to splay from an east dipping low angle detachment surface penetrating the upper crust to depths of 12 13 km the time space evolution of the faults and the associated basins was defined through a review of the stratigraphic data on the syntectonic deposits as regards the overall geometry and the associate sense of shear top to east the clefs sensibly differs from the extensional features described previously in this region but shows surprising affinities with the etrurian fault system an extensional megastructure of the northern apennines remarkable similarities concern the extent the surface and subsurface geometry the timing of activity and the amount of the associated deformation these common characters recognized over a belt nearly 600 km long lead to formulation of a low angle normal fault driven extension geometrical kinematic model which is sound for the whole active extensional belt of italy

quiet time meridional vertical ion drifts at low and middle latitudes observed by rocsat 1 1 in situ ion drift observations from the rocsat 1 satellite near the 600 km altitude and for the years 1999 2003 are used to describe variations in the local time lt distribution of meridional e b drifts at low and middle latitudes for different longitudes and seasons we derive the ion drifts in the direction perpendicular to the magnetic field during quiet times defined by kp 3 and dst 100 nt offsets in the original data are removed by considering separately the northbound and southbound passes in a given volume and by enforcing magnetic conjugacy for the ion drift components perpendicular to the magnetic field three major features are identified for which the variations in latitude longitude and season allow the major drivers of these features to be indicated 1 a latitude magnetic apex height variation in the prereversal after sunset enhancement of the vertical drift that is attributed to similar variations in the flux tube integrated pedersen conductivity 2 the daytime meridional drifts that are largely driven by the e region dynamo show significant latitude variations that are attributed to the relative importance of diurnal and semidiurnal wind fields as a function of latitude and 3 a downward enhancement of the ion drift before sunrise is attributed to a reversal in the f region zonal wind during the nighttime

average equatorial zonal and vertical ion drifts determined from san marco d electric field measurements san marco d electric field measurements have been averaged in terms of their equivalent ion drift to produce an average pattern of equatorial zonal and vertical ion drifts variations with season solar activity kp lunar phase and longitude have been analyzed similarities and some differences from previous jicamarca de 2 and ae e results are seen confirmation is given of the dominance of the f region dynamo in the 1900 2100 local time region the daytime zonal ion drift is larger for high f10 7 values than that for low values there is little variation between high and low values of kp superrotation is evident in this data set and is larger at equinox compared to solstice at the june solstice there are significant differences between the average ion drifts in the longitude sector where the geomagnetic equator is north of the geographic equator indian sector and the sector where the geomagnetic equator is south of the geographic equator peruvian sector the daytime upward velocity is larger in the indian sector than in the peruvian sector and it reverses later in the evening in the indian sector daytime westward zonal velocities are larger and the nighttime eastward velocities are smaller in the indian sector a presunrise enhancement is seen in the downward velocity in the indian sector but not in the peruvian sector significant variations are also seen with the phase of the moon in light of current theory the lunar variations suggest a complex interaction of e and f region dynamo sources with conductivity changing in phase and character with latitude

empirical models of storm time equatorial zonal electric fields ionospheric plasma drifts often show highly complex and variable signatures during geomagnetically active periods due to the effects of different disturbance processes we describe initially a methodology for the study of storm time dependent ionospheric electric fields we present empirical models of equatorial disturbance zonal electric fields obtained using extensive f region vertical plasma drift measurements from the jicamarca observatory and auroral electrojet indices these models determine the plasma drift perturbations due to the combined effects of short lived prompt penetration and longer lasting disturbance dynamo electric fields we show that the prompt penetration drifts obtained from a high time resolution empirical model are in excellent agreement with results from the rice convection model for comparable changes in the polar cap potential drop we also present several case studies comparing observations with results obtained by adding model disturbance drifts and season and solar cycle dependent average quiet time drift patterns when the disturbance drifts are largely due to changes in magnetospheric convection and to disturbance dynamo effects the measured and modeled drift velocities are generally in good agreement however our results indicate that the equatorial disturbance electric field pattern can be strongly affected by variations in the shielding efficiency and in the high latitude potential and energy deposition patterns which are not accounted for in the model these case studies and earlier results also suggest the possible importance of additional sources of plasmaspheric disturbance electric fields

using equilibrium thermodynamics in the study of metasomatic alteration illustrated by an application to serpentinites abstract metasomatic rocks in which mineralogical change is driven by infiltration of an externally derived fluid are challenging for the application of equilibrium thermodynamics because fluid driven changes in rock bulk composition can be faster than diffusive within grain re equilibration nevertheless careful definition of systems in terms of appropriate length scales an informed choice regarding the controlling variables and detailed petrological analysis can provide useful results thermodynamic calculations using methods that solve for equilibrium between a set of independent end member reactions produce valid results regardless of the identity of the controlling variables but determination of the relationship between cause and effect in metasomatic rocks is best performed with some knowledge of the parameters that drive the evolution of the system the correspondence between observations of serpentinised harzburgites from new caledonia and the results of the application of thermodynamic techniques suggest that equilibrium thermodynamics can be applied to these rocks on appropriate small length scales varying from micron to cm the primary drivers for mineralogical change are proposed to be 1 infiltration of a h 2 o fluid which is buffered to lower a o 2 by the rock with resultant production of h 2 and the resulting change in the redox budget of the rocks and 2 gradients in a sio 2 caused by mm to cm scale variation in si mg fe inherited from the harzburgite protolith

rise and fall of a hypothesized seismic gap source complexity in the mw 7 0 16 december 1857 southern italy earthquake abstract on 16 december 1857 a strong earthquake m 7 struck a large portion of the southern apennines about 150 km southeast of naples the earthquake was thoroughly investigated by irish engineer robert mallet who wrote an extensive report that is still regarded as a landmark in observational seismology because of the concentration of damage in the high agri valley and contrary to mallet s own findings for many years the earthquake was referred to as the val d agri earthquake and was believed by most investigators to have ruptured the 20 25 km normal fault lying beneath this intermontane basin the magnitude of the earthquake however and evidence for earthquake complexity suggest that the true rupture length has been so far underestimated we contend that the 1857 earthquake ruptured in a cascade fashion two adjacent and relatively well known faults first the smaller melandro pergola fault commonly believed to represent a seismic gap between the causative faults of the 1857 and of the 1980 irpinia m w 6 9 earthquakes and then the larger agri valley fault proper contemporary chronicles reported a time lapse of 2 3 min between the two ruptures thus effectively making them two independent shocks the rupture must have proceeded unilaterally from the northwestern edge of the melandro pergola fault where mallet placed the earthquake epicenter thus explaining the concentration of damage and attention by rescue crews and subsequent investigators in the southeastern portion of the high agri valley

seismic evidence of longitudinal extension in the southern apennines chain italy the 1997 1998 sannio matese seismic sequence 1 we present evidence of longitudinal extension in the apennines based on data from the 1997 1998 sannio matese seismic sequence the earthquakes occurred between the nw se faults responsible for larger historical earthquakes inversion of focal mechanisms indicates a stress field with a prevailing normal stress characterized by a nnw sse sub horizontal 3 this stress regime is consistent with normal movements along ne sw faults these features suggest that the ne sw faults located in between the nw se faults cannot be interpreted as transfer faults or old faults reactivated during the eastward migration of the chain we propose that the deformation due to the eastward chain migration concentrates along nw se normal faults which are responsible for the largest earthquakes whereas the deformation related to the chain curvature concentrates along ne sw normal faults which are responsible for the lower energy seismic sequences

fault plane solutions and seismicity of the italian peninsula abstract a new fault plane solution map of the italian peninsula is presented in this paper the earthquakes analyzed are included in the period 1905 1980 with magnitudes ranging 4 7 75 earthquakes are located in the crust while 31 are related to the deep and intermediate zone of the calabrian arc the large seismic events of the italian peninsula are generally associated with normal faulting while strike slip motion is mostly related to small earthquakes located along lateral segments of the mountain chain the deep and intermediate earthquakes of the tyrrhenian sea indicate predominant down dip compression and strike slip motion at the boundaries of this benioff zone this last is interpreted as a remnant of a subduction zone active since oligocene extending to 500 km depth with a very small lateral size about 300 km the present tectonics of this benioff zone is strongly conditioned by the lateral bending more so than the gravitational sinking process the coexistence of thrust and normal faulting motion associated to the earthquakes within a few tens of kilometers of each other seems to be explained by the strong lateral inhomogeneities of the crustal rocks present in this region more so than to the depth of the seismogenetic zone and the nature of the faulting process

european mediterranean regional centroid moment tensors 1997 2000 the mediterranean region is seismically very active and undergoing rapid deformation earthquakes as strong as m 6 are present but relatively rare on the other hand moderate magnitude seismicity 4 5 m 5 5 is widespread and often damaging an improved knowedge of moderate magnitude earthquakes can contribute significantly to a better understanding of active tectonics in the region harvard centroid moment tensors cmt today represent the most widely used reference for reliable source mechanisms but modelling seismic sources with the cmt technique for earthquakes with magnitude less than m 5 5 5 is quite difficult since 1997 we are using an extension of the standard cmt algorithm to compute regional centroid moment tensors rcmt for moderate magnitude earthquakes mw as low as 4 0 analyzing intermediate period surface waves from regional and teleseismic seismograms we routinely apply the algorithm to european mediterranean seismicity to produce a catalog of seismic moment tensors for events with magnitude between 4 5 and 5 5 which generally are not included in the harvard cmt catalog in this paper we show the results for earthquakes that occurred between 1997 and 2000 consisting of 252 solutions and we discuss the characteristics of the catalog and the areas where these new data are most relevant

features of the f3 layer in the low latitude ionosphere at sunset the f 3 layer is a common feature within 10 degrees of the magnetic equatorial ionosphere in the daytime according to balan et al 1998 the f 3 layer occurs mainly during the morning noon period due to the combined effect of the upward e x b drift and the neutral wind that provides upward plasma drifts at and above the f 2 layer the f 3 layer occurrence rate is higher in summer and decreases with increasing solar activity in this study the characteristic of the sunset f 3 layer is first investigated using a solar cycle of ionosonde data 1995 2010 from the magnetic equatorial station at jicamarca and compared with the features derived from the four subtropical stations at sao luis fortaleza kwajalein and vanimo evidence shows that the local time distribution of the occurrence of the f 3 layer can extend to the postsunset time 1800 2100 local time the sunset f 3 layer has a strong seasonal dependence occurring mainly during the summertime unlike the daytime f 3 layer the occurrence of the sunset f 3 layer clearly increases and the virtual height of the bottom side of the f 3 layer statistically increases from 620 to 1000 km with increasing solar activity in addition the occurrence of the sunset f 3 layer at the other stations is much less than that at jicamarca these features of the dependence on the season solar activity and latitude are clearly related to the geomagnetic control of the evening prereversal enhancement of the equatorial zonal electric field and geomagnetic configuration

deep crustal carbonates as co 2 fluid sources evidence from metasomatic reaction zones metasomatic reaction zones which developed at marble pelitic schist contacts in a granulite facies terrane in west greenland contain a consistent sequence of five mineralogical zones outward from the carbonates the zones are characterized by the assemblages grossular diopside meionite i meionite anorthite diopside ii anorthite diopside edenitic hornblende iii anorthite enstatite iv plagioclase almandine sillimanite v sphene is superceded by ilmenite between zones ii and iii quartz is present in all zones except zone i scapolite plagioclase clinopyroxene and mica exhibit a small degree of compositional variation which correlates with distance from the carbonate these small compositional variations are superimposed on a strong cao chemical potential gradient compositional features zone distributions and cao activity calculations demonstrate that the zones developed in response to cao diffusion along a chemical potential gradient of 2 kcal m the cao source appears to be carbonate rocks which release calcium as decarbonation reactions proceed the maximum volume of co2 released in this process and that released during discontinuous reactions in the marbles will contribute a total volume of co2 approximately equivalent to the volume of carbonate in the rock calculations demonstrate that a terrane consisting of as little as 8 carbonate will release sufficient co2 to result in complete dehydration of an amphibolite terrane at deep crustal conditions dehydration through co2 release will be accomplished either through rapid burial which would prevent both equilibration of mineral assemblages and co2 release at intermediate crustal levels or through diffusion driven metasomatic reactions which would lead to co2 release primarily at the high temperatures of deep crustal environments the latter process would be the dominant co2 source at deep crustal levels if carbonate rocks occur predominately as relatively thin layers

statistical occurrence analysis and spatio temporal distribution of earthquakes in the apennines italy abstract we present two examples of statistical analysis of seismicity conducted by integrating geological geophysical and seismological data with the aim to characterize the active stress field and to define the spatio temporal distribution of large earthquakes moreover our data will help to improve the knowledge of the seismogenic behavior of the areas and to provide useful information for seismic hazard evaluation the earthquakes are described by two non parametric statistical procedures integrating also tectonic physical parameters to study the spatio temporal variability the results show that the areas are characterized by 1 a stress regime with mainly extensional kinematics 2 tectonic structures mainly oriented with the active stress field s hmin n44 18 in the southern apennines and s hmin n50 17 in the central apennines 3 cluster distribution of seismicity and 4 a high probability of earthquake occurrence m 5 5 in the next 10 years

the vallo di diano and auletta extensional basins in the southern apennines italy a simple model for a complex setting this work has been developed within the 2005 2008 firb project research and development of new technologies for protection and defence of territory from natural risks w p c3 crustal imaging in italy coordinated by p montone funded by the italian ministry of uni versity and research

active stress map of italy we present a new map of the present day stress field in italy obtained from all the available data the map reports 200 horizontal stress directions inferred from 109 borehole breakout data 44 centroid moment tensor solutions 34 other focal mechanisms most of which are from polarity distributions seven stress inversions of microearthquake data two averages of t and p axes of earthquake focal mechanisms in zones of diffuse seismic activity and four fault slip data the integration of breakout data which yield horizontal stress directions with fault plane solutions which reflect the stress regime allows us to obtain an improved map of the present day stress in italy this stress field map can be used for a better comprehension of active tectonic processes for seismic hazard assessment and to foresee the behavior of faults recognized with other methods stress directions obtained from different data although relative to different depth intervals e g 0 7 km for breakouts and 0 20 km for most of the earthquakes and to different tectonic units are consistent since many regions in italy are characterized by an extensional stress regime we report the minimum horizontal stress shmin orientations the map shows that an extensional regime affects most of the apenninic belt conversely a compressional or transpressional regime characterizes the eastern alps the eastern side of the northern apennines and the southern tyrrhenian to northern sicily zone an abrupt change in stress directions marks the transition between northern and southern apennines suggesting that the two arcs are characterized by a different tectonic setting and recent evolution in this paper we report all the data analyzed to date with their geographic coordinates and average stress directions and we describe the main stress provinces in italy in the framework of the tectonic evolution of the region

mineral equilibrium modelling and calculated chemical potential relations of reaction textures in the ultrahigh temperature in ouzzal terrane in hihaou area western hoggar algeria

characterizing the 10 november 2004 storm time middle latitude plasma bubble event in southeast asia using multi instrument observations 1 the development and dynamics of ionospheric plasma bubble pb irregularity during the super storm of 7 11 november 2004 are investigated using the data from a multi instrument network operated in southeast asia analysis of fluctuations in global positioning system total electron content gps tec ionosonde gps scintillation and in situ satellite density data indicates a series of intense pb associated irregularities at equatorial low and middle latitudes in the japanese longitude on 10 november however in the chinese sector the scintillations and pb irregularities are confined within the range of 20 50 n in geographic latitude and 110 125 e in geographic longitude the absence of equatorial pb irregularities in this sector shows a major difference from that in the close by longitude japanese sector in the southern hemisphere australian sector the irregularities occurrence is present as a symmetrical distribution at conjugate latitudes combined analysis of the data from osan and wuhan ionosondes illustrates that the middle latitude spread f irregularities initially develop at the lower part of the f region and then distribute in the whole f region this initiation of spread f at lower altitudes indicates that the middle latitude pb associated irregularities are locally generated these results together with the irregularities occurrence sequence from higher to lower latitudes and the onset time delay of several hours implies that the presence of pb associated irregularities within a latitude range of 20 50 n in the chinese sector cannot be attributed to the effects of prompt penetration electric fields ppefs although the equatorial pbs in the close by longitude are seen to be associated with ppefs the possible mechanism is the f region plasma instabilities triggered by wave structures which act as an external driving force and seed active plasma dynamics and instability growth at middle latitude

seismotectonics of strike slip earthquakes within the deep crust of southern italy geometry kinematics stress field and crustal rheology of the potenza 1990 1991 seismic sequences mmax 5 7 abstract we present a revision and a seismotectonic interpretation of deep crust strike slip earthquake sequences that occurred in 1990 1991 in the southern apennines potenza area the revision is motivated by i the striking similarity to a seismic sequence that occurred in 2002 140 km nnw in an analogous tectonic context molise area suggesting a common seismotectonic environment of regional importance ii the close proximity of such deep strike slip seismicity with shallow extensional seismicity apennine area and iii the lack of knowledge about the mechanical properties of the crust that might justify the observed crustal seismicity a comparison between the revised 1990 1991 earthquakes and the 2002 earthquakes as well as the integration of seismological data with a rheological analysis offer new constraints on the regional seismotectonic context of crustal seismicity in the southern apennines the seismological revision consists of a relocation of the aftershock sequences based on newly constrained velocity models new focal mechanisms of the aftershocks are computed and the active state of stress is constrained via the use of a stress inversion technique the relationships among the observed seismicity the crustal structure of the southern apennines and the rheological layering are analysed along a crustal section crossing southern italy by computing geotherms and two mechanism brittle frictional vs ductile plastic strength rheological profiles the 1990 1991 seismicity is concentrated in a well defined depth range mostly between 15 and 23 km depths this depth range corresponds to the upper pat of the middle crust underlying the apulian sedimentary cover in the footwall of the easternmost apennine thrust system the 3d distribution of the aftershocks the fault kinematics and the stress inversion indicate the activation of a right lateral strike slip fault striking n100 e under a stress field characterized by a sub horizontal n142 trending 1 and a sub horizontal n232 trending 3 very similar to the known stress field of the gargano seismic zone in the apulian foreland the apparent anomalous depths of the earthquakes 15 km and the confinement within a relatively narrow depth range are explained by the crustal rheology which consists of a strong brittle layer at mid crustal depths sandwiched between two plastic horizons this articulated rheological stratification is typical of the central part of the southern apennine crust where the apulian crust is overthrusted by apennine units both the potenza 1990 1991 and the molise 2002 seismic sequences can be interpreted to be due to crustal e w fault zones within the apulian crust inherited from previous tectonic phases and overthrusted by apennine units during the late pliocene middle pleistocene the present strike slip tectonic regime reactivated these fault zones and caused them to move with an uneven mechanical behaviour brittle seismogenic faulting is confined to the strong brittle part of the middle crust this strong brittle layer might also act as a stress guide able to laterally transmit the deviatoric stresses responsible for the strike slip regime in the apulian crust and may explain the close proximity nearly overlapping of the strike slip and normal faulting regimes in the southern apennines from a methodological point of view it seems that rather simple two mechanism rheological profiles though affected by uncertainties are still a useful tool for estimating the rheological properties and likely seismogenic behaviour of the crust

possible fault plane in a seismic gap area of the southern apennines italy revealed by receiver function analysis 1 unusual features in teleseismic receiver function computed at a single three component seismic station reveal the presence of a dipping interface in the shallow crust with a pronounced seismic velocity contrast in the campania lucania region southern apennines italy the locus of this finding is the pergola melandro basin situated between the maximum intensity areas of two of the most destructive earthquakes reported in the italian seismic catalogue the m 7 0 val d agri earthquake 1857 and the ms 6 9 irpinia earthquake 1980 this area is not associated with known historical events and for this reason is currently object of investigation as a potential seismic gap where the probability of future ruptures is higher than in surrounding regions also for the static stress increase caused by the two above mentioned earthquakes through an inversion procedure applied to the computed receiver functions we are able to satisfactorily constrain the strike dip depth and velocity contrast of this crustal discontinuity whose geometric characteristics closely match those proposed by some authors for the sources of the two neighboring earthquakes we argue that the detected interface is the seismogenic source which fills the gap the findings of this study could open new perspectives both in the study of seismic gap areas and in the identification of historical earthquake sources offering a new and effective tool to locate investigate and constrain buried or unknown 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

equatorial f region vertical plasma drifts seasonal and longitudinal asymmetries in the american sector longitudinal and seasonal asymmetries in the evening ionospheric f region plasma vertical drift v sub z enhancements between two longitudinally separated stations situated along the magnetic equator in the american sector are investigated under solar maximum conditions based on results obtained from the analysis of ionosonde data for these stations the two stations are huancayo peru and fortaleza brazil which have markedly different magnetic declination angles the observed asymmetries are interpreted using a detailed numerical simulation of the e and f region electrodynamic coupling process that takes into account also its asymmetry about the magnetic equator arising from the finite magnetic declination angle the results of the simulation show in agreement with observations that the occurrence time of the evening f region vertical drift prereversal peak and its seasonal variation at a station are controlled by the magnetic declination angle at that station which determines the seasonal variation of the sunset times and hence the integrated pedersen conductivity longitudinal gradient at its magnetic conjugate e layers the amplitude of the prereversal peak on the other hand undergoes the influence of the magnetic declination angle as well as of the thermospheric zonal wind component

geomorphic evidence of quaternary tectonics within an underlap fault zone of southern apennines italy abstract a composite seismic source the irpinia agri valley fault zone located in the axial sector of the fold and thrust belt of southern apennines italy is investigated this composite source is made up of a series of nearly parallel nw striking normal fault segments which caused many historical earthquakes two of these fault segments known as the san gregorio magno and pergola melandro and the fault related mountain fronts form a wedge shaped right stepping underlap fault zone this work is aimed at documenting tectonic geomorphology and geology of this underlap fault zone the goal is to decipher the evidence of surface topographic interaction between two bounding fault segments and their related mountain fronts in particular computation of geomorphic indices such as mountain front sinuosity s mf water divide sinuosity s wd asymmetry factor af drainage basin elongation b s relief ratio r h hypsometry hi normalized steepness k sn and concavity is integrated with geomorphological analysis the geological mapping and structural analysis in order to assess the recent activity of the fault scarp sets recognized within the underlap zone results are consistent with the nw striking faults as those showing the most recent tectonic activity as also suggested by presence of related slope deposits younger than 38 ka the results of this work therefore show how the integration of a multidisciplinary approach that combines geomorphology morphometry and structural analyses may be key to solving tectonic geomorphology issues in a complex fold and thrust belt configuration

late quaternary tectonics of the vallo di diano basin southern apennines italy italian ministry of university and research project firb research and development of new technologies for protection and defence of territory from natural risks w p c3 crustal imaging in italy

passive seismology and deep structure in central italy in the last decade temporary teleseismic transects have become a powerful tool for investigating the crustal and upper mantle structure in order to gain a clearer picture of the lithosphere asthenosphere structure in peninsular italy between 1994 and 1996 we have deployed three teleseismic transects in northern central and southern apennines in the framework of the project geo modap european community contract ev5v ct94 0464 some hundreds of teleseisms were recorded at each deployment which lasted between 3 and 4 months although many analyses are still in progress the availability of this high quality data allowed us to refine tomographic images of the lithosphere asthenosphere structure with an improved resolution in the northern and central apennines and to study the deformation of the upper mantle looking at seismic anisotropy through shear wave splitting analysis also a study of the depth and geometry of the moho through the receiver function technique is in progress tomographic results from the northernmost 1994 and the central 1995 teleseismic experiments confirm that a high velocity anomaly hva does exist in the upper 200 250 km and is confined to the northern apenninic arc this hva already interpreted as a fragment of subducted lithosphere is better defined by the new temporary data compared to previous works based only on data from permanent stations no clear high velocity anomalies are detected in the upper 250 km below the central apennines suggesting either a slab window due to a detachment below southern peninsular italy or a thinner perhaps continental slab of adriatic lithosphere not detectable by standard tomography we found clear evidence of seismic anisotropy in the uppermost mantle related to the main tectonic processes which affected the studied regions either ne sw compressional deformation of the lithosphere beneath the mountain belt or arc parallel asthenospheric flow both giving nw se fast polarization direction and successive extensional deformation e w trending in the back arc basin of northern tyrrhenian and tuscany preliminary results of receiver function studies in the northern apennines show that the moho depth is well defined in the tyrrhenian and adriatic regions while its geometry underneath the mountain belt is not yet well constrained due to the observed high complexity

the italian cmt dataset from 1977 to the present abstract the ingv harvard european mediterranean regional centroid moment tensor rcmt catalog collects solutions routinely computed since 1997 for earthquakes with moderate magnitude 4 5 m 5 5 in the mediterranean region the database represents an extension to smaller magnitudes of the harvard global cmt catalog based on analysis of seismograms recorded at regional distance and modeling of intermediate period surface waves the catalog includes about 600 events 200 of which in the italian region this study extends the catalog back in time for the italian region as long as made possible by available digital data i e since 1977 with the same analysis and inversion method used for current seismicity as a result we present here 65 new moment tensors for years between 1977 and 1997 these solutions represent 45 of the total number of events analyzed the existing seismograms being often too scarce to allow a stable solution the new dataset includes events in many seismic zones where moderate seismicity had previously been scarcely documented e g the po plain the central to southern apennines and the adriatic sea the complete dataset including previously determined rcmts and cmts represents the seismic deformation in the italian area during the last 25 years

a simulation study of the equatorial ionospheric response to the october 2013 geomagnetic storm the ionospheric observation from ionosonde at sao luis 2 5 s 44 2 w 6 68 s dip latitude around the magnetic equator showed that the nighttime ionospheric f2 layer was uplifted by more than 150 km during the october 2013 geomagnetic storm the changes of the f2 peak height hmf2 at the magnetic equator were generally attributed to the variations of vertical drift associated with zonal electric fields in this paper the thermosphere ionosphere electrodynamics general circulation model tiegcm simulation results are utilized to explore the possible physical mechanisms responsible for the observed increase of hmf2 at sao luis the tiegcm generally reproduced the changes of f2 peak electron density nmf2 and its height hmf2 during the main and recovery phases of the october 2013 storm a series of controlled simulations revealed that storm time hmf2 changes at the magnetic equator are not purely associated with the changes of electric fields horizontal plasma transport due to meridional winds and thermospheric expansion also contributed significantly to the profound increase of nighttime hmf2 observed at sao luis on 2 october moreover the changes of meridional winds and neutral temperature in the equatorial region are associated with storm time travelling atmospheric disturbances originating from high latitudes

fluid rock interaction in some shear zones from the pyrenees mylonites from shear zones cutting hercynian gneisses in the central pyrenees have been studied in thin section and using the electron microprobe the shear zones contain retrogressive greenschist facies assemblages implying introduction of an aqueous fluid during deformation in the zones textural evidence suggests that fluid rock interaction occurred throughout the active life of the shear zones whole rock chemical changes during deformation are documented in a variety of mylonitic lithologies and retrogressed country rocks the overall effect was to reduce chemical differences between lithologies activity diagrams show that this would be expected if a hydrous fluid was circulating between different lithologies during deformation in most cases fluid rock ratios were relatively small resulting in gradual chemical changes and repeated recrystallization open system behaviour with reduction in the number of phases is seen in some granite mylonites suggesting focusing of fluid movement in parts of the shear zones continual fluid rock interaction may have led to reaction enhanced ductility in the shear zones over a long period of time the source of fluid is uncertain but may be related to underthrusting of material beneath the area investigated

using calculated chemical potential relationships to account for replacement of kyanite by symplectite in high pressure granulites calculated mineral equilibria are used to account for the formation of sapphirine plagioclase spinel plagioclase and corundum plagioclase symplectites replacing kyanite in quartz plagioclase garnet kyanite granulite facies gneisses from the southern domain of the athabasca granulite terrane a segment of the snowbird tectonic zone in northern saskatchewan canada metamorphic conditions of 14 kbar and 800 c are established for the high pressure garnet kyanite assemblage using constraints from p t pseudosections and zr in rutile thermometry replacement of kyanite by symplectites reflects the reaction of kyanite with the matrix following near isothermal decompression to 10 kbar the chemical potential gradients developed between the kyanite and the matrix led to diffusion that attempted to flatten the gradients kyanite persisting as a stable phase while it is consumed by symplectite from its edge in this local equilibrium model the mineral and mineral compositional spatial relationships are shown to correspond to paths in na2o cao k2o feo mgo in the model chemical system na2o cao k2o feo mgo al2o3 sio2 nckfmas with sio2 and al2o3 taken to be completely immobile the values of na2o and cao are constrained by fixing p t conditions and choosing appropriate na2o and cao values that correspond to the observed plagioclase compositions feo mgo diagrams show the corresponding spatial relationships with kyanite and the symplectite phases these results demonstrate that the replacement of kyanite by sapphirine plagioclase and spinel plagioclase appears to be metastable with respect to replacement by corundum plagioclase replacement by corundum plagioclase does also occur apparently overprinting pre existing symplectite and also kyanite ignoring corundum the resulting diagrams account for the spatial relationships and compositions observed in the spinel plagioclase and sapphirine plagioclase symplectites they are predicted to occur over both a wide range of p t conditions 6 11 kbar 650 850 c and plagioclase compositions xan 0 5 0 9 the wide range of p t conditions that may result in identical spatial and compositional relationships suggests that such reaction textures may be of limited use in accurately quantifying the p t conditions of retrograde metamorphism

storm time dependence of equatorial disturbance dynamo zonal electric fields we use jicamarca radar observations of f region vertical plasma drifts and auroral electrojet indices during 1968 1988 to study the characteristics and temporal evolution of equatorial disturbance dynamo zonal electric fields these electric fields result from the dynamo action of storm time winds and or thermospheric composition changes driven by enhanced energy deposition into the high latitude ionosphere during geomagnetically active conditions the equatorial vertical drift perturbations last for periods of up to 30 hours after large increases in the high latitude currents on the average this process can be described by two basic components with time delays of about 1 12 hours and 22 28 hours between the high latitude current enhancements and the equatorial velocity perturbations our data indicate strong coupling between dynamo processes with different timescales the short term disturbance dynamo drives upward equatorial drifts eastward electric fields at night with largest amplitudes near sunrise and small downward drifts during the day these perturbation drifts are in good agreement with results from the blanc richmond disturbance dynamo theory the dynamo process with time delays of about a day drives upward drift velocities at night with largest values near midnight and downward drifts in the sunrise noon sector in this case the amplitudes of the disturbance drifts maximize during geomagnetically quiet times preceded by strongly disturbed conditions we also present results of a new equatorial storm time dependent empirical model which illustrate the characteristics of the vertical disturbance dynamo drifts

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

tio2 activity in metamorphosed pelitic and basic rocks principles and applications to metamorphism in southeastern canadian cordillera the activity of tio2 can be precisely defined as a function of pressure temperature and activities of other components for common mineral assemblages in metapelites ilmenite quartz garnet plagioclase al2sio5 and in metabasites plagioclase sphene ilmenite quartzgarnet these mineral assemblages can be modelled by the equilibria 1 3ilmenite al2sio5 2quartz almandine 3tio2 2 anorthite 2sphene grossular 2tio2 quartz 3 3anorthite 3quartz 6ilmenite grossular 6tio2 2almandine these mineral assemblages can be used at a text tio text 2 1 rutile saturation and a given t to get maximum pressure limits of some metapelites and metabasites when electron microprobe analyses of mineral grains adjacent to ti bearing phases are made these data give maximum pressure estimates in reasonable agreement with other geobarometers the activity of tio2 in many metapelites is very near rutile saturation but for metabasites the activity of tio2 in some sillimanite zone rocks is as low as 0 6 the solubility of tio2 in biotite hornblende and garnet is a complex function of t p the activities of components in coexisting minerals and crystal chemical constraints in these minerals at a given p and t the solubility of tio2 in biotite and hornblende does not appear to be strongly dependent upon a text tio text 2 1 for sphene and ilmenite versus rutile bearing assemblages

metasomatism and graphite formation at a lithological interface in malaspina alpine corsica france multiple pieces of geologic evidence suggest that interfaces between contrasted lithologies exert a strong control on the fate of volatiles in subduction zones here we present results from a contact between serpentinites and sediments located in corsica and metamorphosed in the blueschist facies during the alpine orogeny it was shown previously that carbonates in the sediments have been reduced to graphitic carbonaceous material within a 5 10 cm thick reaction zone at the contact with serpentinites in an effort to investigate the mechanisms governing this unusual process bulk rock geochemical analyses incorporating a statistical analysis of compositional data are presented observations show that the fate of c was decoupled from that of other elements such as o h and large ion lithophile elements e g k sr ba as that were extensively leached from the reaction zone notably na is strongly enriched in the reaction zone and structurally linked to pectolite reducing conditions manifested by the depletion of o in the reaction zone compared to the bulk metasediment were likely maintained by the presence of fe ii in the serpentinite moreover thermodynamic calculations show that the low solubility of carbon in coh fluids at high pressure and low temperature conditions was the main driver for graphite precipitation synchronously with carbonate destabilization this may have been kinetically favored by the presence of already existing graphitized carbonaceous material and phengite in the metasediment limited lateral flow might have contributed as well to the geochemical and petrological patterns observed in these rocks

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

equatorial ionospheric vertical plasma drift model over the brazilian region comparison between equatorial inospheric f region vertical plasma drift from satellite measurements fejer et al 1995 for the brazilian longitude sector and the drifts derived from ionosonde measurements around sunset shows significant differences on the prereversal peak behavior during solstices of high solar activity periods using ionosonde measurements around sunset and satellite measurements at other local times we constructed an ionospheric vertical plasma drift model that is representative of the equatorial region over the brazilian longitudes where the magnetic declination is around 20 the so derived drift model here called idm ionosonde drift model is used as an input to the sheffield university plasmasphere ionosphere model supim it is shown that the f layer heights given by supim with idm are in good agreement with ionosonde measurements over the brazilian longitudes and that idm better simulates the f layer heights than the averaged drifts given by the satellite drift model fejer et al 1995

equatorial f region zonal plasma drifts we have examined in detail the f region plasma drifts measured at jicamarca peru during 1978 1981 a period of high solar activity and compared these drifts with jicamarca data taken during periods of lower activity as well as with other equatorial zonal neutral wind and plasma drift measurements the increase in solar activity causes larger nighttime eastward plasma drifts at jicamarca and delays the morning reversal time from eastward nighttime to westward daytime drifts the radar data seem to be in good agreement with nighttime neutral wind measurements made by the de 2 satellite but are systematically smaller than spaced receiver drifts measured with both the scintillation and the vhf polarimeter techniques for integration times of 20 30 min but perhaps not for shorter integrations the jicamarca zonal plasma drifts measured with both the incoherent scatter and the radar interferometer technique change little with altitude near the f region electron density peak and above however at nighttime below the f peak there is a clear shear in the zonal plasma drifts with decreasing eastward drifts below the f peak reversing to westward drifts at lower altitudes the nighttime profiles of the equatorial plasma drifts are in good agreement with the results from recent numerical models of the equatorial ionosphere

on the height variation of the equatorial f region vertical plasma drifts we have used improved incoherent scatter radar measurements at the jicamarca radio observatory to study the height variation of the f region vertical plasma drift velocity driven by the zonal electric field during moderately quiet conditions preliminary results indicate a nearly linear change of the vertical drift velocity with altitude between 200 and 700 km but with considerable day to day variations in the value of the slope on the average the velocity gradients are positive in the late night and morning periods and negative during the afternoon and evening hours simultaneous vertical and zonal drift measurements confirm that the measured height variation of the vertical drift is consistent with the existence of a curl free electric field in the low latitude ionosphere the time dependence of the jicamarca vertical drifts extrapolated to higher altitudes closely resembles the diurnal variation of the drift component due to the zonal electric field observed at f region heights over arecibo

analysis of the 9 september 1998 mw 5 6 mercure earthquake sequence southern apennines italy a multidisciplinary approach abstract the mercure earthquake mw 5 6 of september 9 1998 and the associated aftershocks occurred in a small pleistocene holocene continental basin of the southern apennines in a region of low instrumental and moderate historical seismicity seismological photogeological and field survey data were analyzed and integrated in order to identify the likely seismogenic structure to depict its 3 d geometry and kinematics and to provide further constraints to the seismogenic potential of the rupture processes in the study area the mainshock occurred at the nw edge of the seismic sequence 40 03 n and 15 95 at a depth of 10 5 1 5 km the aftershocks volume was determined from the relocation of about 200 events 1 1 ml 3 9 registered by local networks from september 10 to october 12 1998 the relocation procedure was based on choosing p and s waves for all the events and the definition of ten 9 layers velocity models appropriate for the different stations the kinematics of the seismogenic deformation was defined through the computation of 36 well constrained focal mechanisms the seismological and geological stress tensors were determined through inversion of focal mechanisms and fault slip data both of them resulted in the tensional type with ene wsw and ne sw trending 3 axis respectively the map and the section distribution of the aftershocks sequence depicts an average nw se striking and 60 sw dipping seismogenic volume most of the events 80 were located at depths between 3 and 8 km in the footwall of the mercure basin mbb boundary fault but along the possible down dip continuation of a previously unidentified n120 e striking and wsw dipping holocene normal fault alignment which extends from castello seluci to piana perretti and timpa della manca cpst fault a small percentage of events 10 were located at depths between 10 and 12 km where the cpst seismogenic fault may detach the reconstructed rupture area ra of the mercure 1998 earthquake has an along strike length l of about 9 km and a down dip width w of about 9 km yielding a total area of approximately 81 km 2 on the other hand the l and w dimension of the entire individual seismogenic structure identified as responsible for the earthquake e g the cpst fault are about 19 and 12 km respectively with a consequent ra of about 230 km 2 this may imply a maximum magnitude mw equal to 6 3 which lead us to compare the mercure area in terms of seismogenic hazard to the adjacent pollino castrovillari area where strong paleoseismological events are documented

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

longitudinal dependence of equatorial f region vertical plasma drifts in the dusk sector the effect of solar activity on the postsunset peak of f region vertical plasma drift at kodaikanal 77 28 e dip 3 n is determined as a function of season and for two levels of magnetic activity using extensive hf phase path observations and compared with that at jicamarca 75 w dip 2 n reported in the literature the postsunset peak vertical velocity vzp at kodaikanal increases linearly with 10 7 cm solar flux f10 7 irrespective of season and level of magnetic activity the sensitivity of vzp to solar flux changes is more at jicamarca than at kodaikanal during equinoxes and december solstice this feature is virtually absent in june solstice the seasonally averaged values of dusktime vertical velocity at kodaikanal for moderate to high solar flux conditions and quiet magnetic conditions kp 3 are in reasonable agreement with those reported very recently for the indian sector 80 e from ae e satellite data fejer et al 1995 in june solstice the evening upward vertical velocities at kodaikanal are on the average much smaller than in the pacific sector 160 200 e while the postreversal downward velocities are more or less of the same magnitude in all longitude sectors except in the western american sector 230 310 e where there they are higher the present study supports the emerging view that the dusktime equatorial f region vertical plasma drifts exhibit large longitudinal variations during the june solstice

the role of perfectly mobile components in metamorphism the concept of perfectly mobile components was introduced to petrologic literature by d s korzhinskii 1936 1950 korzhinskii noticed that in metasomatic rocks the content of certain components was more or less fixed throughout the metasomatic process but that the content of other components either volatile ones such as h20 and co2 or those with appreciable solubility in pore fluid changed greatly during metasomatism compare shaw 1956 components of the first type were designated inert and of the second type perfectly mobile in english translation the terms perfectly mobile and inert were redefined by korzhinskii in the context of his thermodynamic theory of open systems the result being that the words lost their literal meaning and acquired an esoteric technical significance the redefinition was unfortunate as it provides an example of how the use of common words in multiple senses can lead to misunderstanding the terminology and concepts have been widely used discussed and criticized in petrologic studies of metamorphic and metasomatic rocks the purpose of this paper is to review the historical development of the concepts of inert and perfectly mobile components problems that have arisen in the application of the concepts to understanding rocks are discussed the concepts are then evaluated in the light of current research in metamorphic petrology

a decade of passive seismic monitoring experiments with local networks in four italian regions we report on four seismic monitoring experiments that in the past ten years we carried out with dense local networks in seismically active italian areas where for at least a year tens of three component seismic stations were set up to record microseismicity the areas observed are alpago cansiglio located in the venetian alps citta di castello in the northern apennines marsica in the central apennines and val d agri located in the southern apennines we produced homogeneous catalogues regarding earthquake locations and local magnitudes to investigate seismicity patterns during an inter seismic period the four regions are characterised by different kinematics strain rates and historical recent seismicity we investigate earthquake distribution in space time and size obtaining reference seismic rates and parameters of the gutenberg and richter law we declustered the catalogues to look for coherent signs in the background seismic activity despite a difference in the catalogues magnitudes of completeness due both to the diverse detection threshold of the local networks and different seismic release we detect and observe two common main behaviours a the alpago cansiglio and marsica regions are characterised by a relatively lower rate of seismic release associated to the episodic occurrence of seismic sequences with the largest event being 3 ml 4 in these areas the seismicity is not localised around the main faults b the citta di castello and val d agri regions have a relatively high rate of seismicity release almost continuously with time and the increase in earthquake production is not clearly related to seismic sequences in these areas the seismicity nucleates around defined fault systems and is usually lower than ml 3 we suggest that the presence of over pressured fluids in the citta di castello and val d agri uppermost crustal volume may favour and mould the higher rate of microseismic release

magnetic declination control of the equatorial f region dynamo electric field development and spread f we have carried out a comparative study of the evening prereversal enhancements in the equatorial f region vertical ionization drift velocities vz over fortaleza 4 s 38 w brazil and jicamarca 12 s 77 w peru two magnetic equatorial stations in the american zone the results show profound dissimilarities in the seasonal trends in the times and widths of the vz prereversal peak which reflect in the spread f characteristics as well at the two stations the dissimilarities are shown to be arising mainly from the difference in the magnetic field declination angles that causes differences in the conjugate e region sunset durations and hence in the f region polarization electric field development rates at the two stations

along depth stress rotations and active faults an example in a 5 km deep well of southern italy 1 we have analyzed a 1500 m section at 3 9 to 5 4 km depth in a well of the southern apennines in order to better characterize the local active stress field and its correlation with tectonic structures in this paper we present and discuss the results obtained from the comparison between breakouts and structural analysis from dipmeter data we have found that the mean breakout direction is in agreement with the regional stress field that in this area is characterized by normal faulting 1 v with ne sw trending extension horizontal 3 since the regional stress field is relatively well known in this region we could detect and study some anomalous horizontal stress directions along the well which we interpret as due to faults crosscutting the borehole a detailed comparison between the breakout inferred stress variations along depth and the faults identified by the dipmeter analysis reveals that some of these faults are associated with stress rotations whereas others do not show any variation the former can be interpreted either as open fractures or as faults that slipped recently with a near complete stress drop and the latter can be interpreted as sealed faults in particular we found that the main thrust faults of the area mainly active in pliocene times appear to be sealed whereas e w trending high angle normal faults determine strong stress rotations suggesting that they are the main active structures of the region this suggests that the study area is located in a transfer zone between the two main apenninic nw se trending fault systems which ruptured in the last 150 years this study has shown that a detailed analysis of the structural and geometrical characteristics of deep wells can be used for the reconnaissance of active structures this approach can contribute to seismic hazard studies and if carried out in an oil bearing section can help to maximize the hydrocarbon production

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

comparison between nighttime ionosonde incoherent scatter radar ae e satellite and hf doppler observations of f region vertical electrodynamic plasma drifts in the vicinity of the magnetic equator 1 nighttime f region vertical drifts were made using an ionosonde for the equatorial station ibadan 7 4 n 3 9 e 6 s dip from 1 year of data during 1957 1958 international geophysical year igy that corresponds to a period of solar maximum for undisturbed condition we compare the seasonal vertical drifts with measurements made by incoherent scatter radar ae e satellite and hf doppler for equatorial f region vertical drifts we find a comparable variability pattern during periods of high f layer heights during equinox and the december solstice and the opposite behavior occurs during june solstice the drifts are predominantly downward between 2000 and 0500 lt intervals ionosonde drifts are smaller in values by either a factor of two or three than other methods except for consistent june solstice ionosonde and satellite magnitudes the equinoctial average prereversal enhancements measured by the four techniques are roughly comparable about 36 m s and occur at the same local time 1900 lt for all the seasons the evening reversal times are similar apart from june solstice that exhibits large variations the morning reversal times are also in accord except for the equinoctial jicamarca drift our observations indicate that ionosonde drifts measurements are in better agreement with vertical drifts results at other equatorial stations

moment tensor analysis of the central italy earthquake sequence of september october 1997 the larger earthquakes in the umbria marche central italy seismic sequence of september october 1997 are analyzed using long period seismograms from the mediterranean seismographic network mednet and additional data from the global seismographic network gsn we modify the harvard centroid moment tensor cmt algorithm to allow moment tensor inversion of long period waveforms primarily rayleigh and love waves for small earthquakes at local to regional distances 5 5 in the sequence moment tensors have previously been determined using teleseismic waveforms and standard methods of analysis our results agree well with those of earlier studies we determine additional moment tensors for the largest foreshock and 10 aftershocks with mw 4 2 the earthquakes are characterized by normal faulting mechanisms with a ne sw tension axis and the presumed fault plane dips towards the sw only one of the fourteen events studied has a different faulting geometry indicating instead right lateral strike slip faulting on a plane oriented approximately e w or left lateral faulting on a plane oriented n s the september 26 mainshock 09 40 ut accounts for only approximately 50 of the total moment release in the sequence

radar and satellite global equatorial f region vertical drift model we present the first global empirical model for the quiet time f region equatorial vertical drifts based on combined incoherent scatter radar observations at jicamarca and ion drift meter observations on board the atmospheric explorer e satellite this analytical model based on products of cubic b splines and with nearly conservative electric fields describes the diurnal and seasonal variations of the equatorial vertical drifts for a continuous range of all longitudes and solar flux values our results indicate that during solar minimum the evening prereversal velocity enhancement exhibits only small longitudinal variations during equinox with amplitudes of about 15 20 m s is observed only in the american sector during december solstice with amplitudes of about 5 10 m s and is absent at all longitudes during june solstice the solar minimum evening reversal times are fairly independent of longitude except during december solstice during solar maximum the evening upward vertical drifts and reversal times exhibit large longitudinal variations particularly during the solstices in this case for a solar flux index of 180 the june solstice evening peak drifts maximize in the pacific region with drift amplitudes of up to 35 m s whereas the december solstice velocities maximize in the american sector with comparable magnitudes the equinoctial peak velocities vary between about 35 and 45 m s the morning reversal times and the daytime drifts exhibit only small variations with the phase of the solar cycle the daytime drifts have largest amplitudes between about 0900 and 1100 lt with typical values of 25 30 m s we also show that our model results are in good agreement with other equatorial ground based observations over india brazil and kwajalein

deep structure of the campanian lucanian arc southern apennine italy abstract recent exploration activities and successful discovery of large oil fields in the upper val d agri area southern apennine italy have encouraged the collection of large quantities of geological and geophysical data and their integration into comprehensive geological models here we present a series of structural profiles based on several hundred kilometres of seismic lines two and three dimensional and the results of many deep wells the best seismic lines have been extensively reprocessed and also tied to magnetotelluric data geological interpretations of those lines have been interactively tested and verified by gravity and magnetic modelling and structural balancing the wells and seismic data demonstrate that the fundamental tracts of the deep architecture of the orogen as it appears today were developed only at the end of the late pliocene the final closure of the ensialic shear zone responsible for the subduction of at least 150 km of continental lithosphere originally underlying the lagonegro basin can be dated as early pliocene the involvement of the inner apulian platform in the core of the belt and the activation of a new and more external left lateral oblique ensialic shear zone can be constrained to the late pliocene pleistocene the seismic profiles clearly show the underthrusting of the outer apulian platform unit beneath the inner apulian platform unit the thick skinned character of the plio pleistocene contractional structures is evident from the structural profiles this geometry is constrained by gravity magnetic data and structural considerations according to the relatively steep angle of dip about 10 of the apulian foreland beneath the chain the structural profiles depict the general architecture of the campanian lucanian arc the apennine platform and lagonegro unit are largely allochthonous and a part of the lagonegro basement could be buried below the apennine platform sole thrust the neogene plastic successions of the apennine platform and lagonegro basin were detached and now outcrop in the bradanic foredeep the inner apulian platform constitutes a huge thrust sheet structured as a wide antiform in the core of the belt its regional culmination roughly corresponds to the val d agri area extensional and transtensional structures cross cut the pre existing compressional structures as shown by the quaternary valleys of vallo di diano and val d agri the profiles shown also highlight the existing contrast between the deep structures in the core of the belt and the tectonic style of the lagonegro liguride and sicilide units these units were in fact subjected to brittle ductile deformation under metamorphic part of liguridi units and deep diagenetic to anchizonal conditions lagonegro units and were affected by a general overthrust shear directed towards the ne the inner apulian platform was on the contrary involved in the thrust belt together with its basement whereas the outer apulian platform affected by a subduction underwent a regional bending with associated normal faulting

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

active extension in val d agri area southern apennines italy implications for the geometry of the seismogenic belt summary integration of geologic geomorphologic and seismologic data sets is used to reconstruct the recent tectonic evolution and active deformation pattern in the val d agri area located in the seismically active axial sector of the southern apennines italy the western portion of the apennines thrust belt has been affected by pliocene quaternary extension during easterly roll back and crustal delamination of the adriatic slab the bulk of quaternary extension has been accommodated by sw dipping oblique and normal faults which have attained mature morphologic and structural features and nowadays separate mountain ranges from intermontane basins however in the present seismogenic belt coseismic faulting locally occurs on ne dipping structures which might cut the inherited pleistocene landscape in the val d agri basin in spite of the large early middle pleistocene displacement occurred on sw dipping faults bordering its eastern flank our investigations show that the recent basin evolution has been controlled by a ne dipping fault system monti della maddalena fault system mmfs this fault system cuts across the monti della maddalena range west of the agri valley and has not yet created an evident tectonic landscape notwithstanding fault motion since the middle pleistocene might explain geomorphologic and hydrographic anomalies of the agri river and its valley where fault controlled subsidence has captured the river course and produced an aggrading plain within a regional uplift context recent and ongoing motion is documented by fault scarplets in loose deposits 14c ages of palaeosols and the spatial relation with low to moderate instrumental seismicity results from fault kinematic analysis are compatible with fault plane solutions of local and regional seismic events and indicate ne sw oriented extension recognition of the mmfs as a potential seismogenic fault increases the longitudinal extent of the ne dipping morphologically immature seismic sources in the southern apennines and argues against the range bounding fault model for active extension in the region the regional size of the ne dipping seismogenic belt may result from impingement of a mantle wedge beneath the apenninic chain and possibly track the external front of crustal delamination

reactivation of deep faults beneath southern apennines evidence from the 1990 1991 potenza seismic sequences we relocate the 1990 1991 potenza southern apennines belt italy sequences and calculate focal mechanisms this seismicity clusters along an e w dextral strike slip structure second order clusters are also present and reflect the activation of minor shears the depth distribution of earthquakes evidences a peak between 14 and 20 km within the basement of the subducting apulian plate the analysed seismicity does not mirror that of southern apennines which include nw se striking normal faults and earthquakes concentrated within the first 15 km of the crust we suggest that the e w faults affecting the foreland region of apennine propagate up to 25 km of depth the potenza earthquakes reflect the reactivation of a deep preexisting fault system we conclude that the seismotectonic setting of apennines is characterized by nw se normal faults affecting the upper 15 km of the crust and by e w deeper strike slip faults cutting the crystalline basement of the chain

global cmt analysis of moderate earthquakes mw 4 5 using intermediate period surface waves a new method for calculating centroid moment tensor cmt solutions for moderate sized earthquakes is presented and tested in the new algorithm which is a modification to the standard harvard cmt method intermediate period surface waves are included in the inversion for source parameters the dispersion of teleseismic surface waves in the period range 40 to 150 sec is predicted by interpolation of recent global phase velocity maps the method is tested on a set of 20 moderate and large 5 2 mw 7 2 earthquakes with known mechanisms the retrieved mechanisms are similar to the previous results even when noise is added to the seismograms to simulate earthquakes of a smaller magnitude mw 4 5 the inversion algorithm is applied to the 1993 klamath falls mainshock and aftershock sequence and the results compare well with earlier results a catalog of mw 4 5 focal mechanisms for greece and surrounding areas for the first six months of 1995 is derived using the new method of analysis

a major seismogenic fault in a silent area the castrovillari fault southern apennines italy summary large historical earthquakes in italy define a prominent gap in the pollino region of the southern apennines geomorphic and palaeoseismological investigations in this region show that the castrovillari fault cf is a major seismogenic source that could potentially fill the southern part of this gap the surface expression of the cf is a complex 10 13 km long set of prominent scarps trenches across one scarp indicate that at least four surface faulting earthquakes have occurred along the cf since late pleistocene time each producing at least 1 m of vertical displacement the length of the fault and the slip per event suggest m 6 5 7 0 for the palaeoearthquakes preliminary radiocarbon dating coupled with historical considerations imply that the most recent of these earthquakes occurred between 380 bc and 1200 ad and probably soon after 760 ad no evidence for this event has been found in the historical record we estimate a minimum recurrence interval of 1170 years and a vertical slip rate of 0 2 0 5 mm yr for the cf which indicates that the seismic behaviour of this fault is comparable to other major seismogenic faults of the central southern apennines the lack of mention or the mislocation of the most recent event in the historical seismic memory of the pollino region clearly shows that even in italy which has one of the longest historical records of seismicity a seismic hazard assessment based solely on the historical record may not be completely reliable and shows that geological investigations are critical for filling possible information gaps

incoherent scatter radar ionosonde and satellite measurements of equatorial f region vertical plasma drifts in the evening sector studies of equatorial f region evening vertical plasma drifts using different measurement techniques have produced conflicting results we examine the relationship of incoherent scatter radar and ionosonde drift observations over the peruvian equatorial region and ae e satellite drifts for different geophysical conditions our data show that there is large day to day variability on the ratios of radar and ionosonde drifts but on the average the measurements from these two techniques are in fair agreement during low and moderate solar flux conditions for high solar activity however the jicamarca evening drifts during equinox and december solstice are significantly larger than the ionosonde drifts these results can be explained by the different height ranges of the radar and ionosonde measurements and the increase of the upward drift velocity with height below the f region peak this altitudinal variation is related to the longitudinal gradient of the zonal plasma drifts as a result of the curl free electric field condition our results also indicate that during equinox the increase of the vertical prereversal velocity enhancement with solar activity is largely longitude independent

paleoseismicity of the ovindoli pezza fault central apennines italy a history including a large previously unrecorded earthquake in the middle ages 860 1300 a d geomorphic and trenching investigations along the ovindoli pezza fault show that this normal fault is one of the major seismogenic faults in the central apennines we found clear geological evidence for three holocene surface faulting earthquakes on this fault the most recent earthquake occurred in the middle ages between 860 and 1300 a d the penultimate occurred about 1900 b c or shortly after and the oldest probably occurred between 3300 and 5000 b c although the most recent surface faulting earthquake occurred during historical time no evidence for it have been found in the historical record slip per event ranges between 2 and 3 m and the length of the rupture is at least 12 20 km suggesting m 6 5 7 0 for the paleoearthquakes the dip slip rate determined from trenching is 0 7 1 2 mm yr and is consistent with the long term slip rate of 0 9 2 5 mm yr lower values preferred obtained from displaced geomorphic features trench data combined with long term slip rate estimates suggest the recurrence interval is longer than a millennium and possibly as long as 3300 years the time elapsed since the most recent earthquake is 700 1130 years the seismic behavior of the ovindoli pezza fault is consistent with other well known seismogenic faults of the central and southern apennines the lack of mention or mislocation of the most recent event on the ovindoli pezza fault in the historical record of the past two millennia should be attributed mainly to the unsettled cultural and social conditions and poor economic state that characterized the middle ages especially in thinly populated regions such as the central apennines this example highlights an intrinsic limit of the historical data and raises the possibility that other regions considered seismically quiet on the basis of a long historical record may in reality have had large earthquakes that were not recorded

details of the gabbro to eclogite transition determined from microtextures and calculated chemical potential relationships permian aged metagabbros from the eclogite type locality in the eastern european alps were partially to completely transformed to eclogite during eoalpine intracontinental subduction microtextures developed along a preserved fluid infiltration and reaction front in the gabbros record the incipient gabbro to eclogite transition allowing the details of the eclogitization process to be investigated original anorthite rich igneous plagioclase is pervasively replaced by fine grained intergrowths of clinozoisite kyanite and na rich plagioclase where plagioclase was in contact with igneous orthopyroxene 100 200 m thick bimineralic coronae of symplectic kyanite and diopsidic clinopyroxene form along the edges of the grains the rims of igneous orthopyroxene develop a complementary bimineralic corona of diopsidic clinopyroxene and garnet igneous clinopyroxene does not show any breakdown textures however jadeite content gradually increases towards the rims in addition exsolution lamellae inherited from the igneous clinopyroxene become progressively more jadeitic as eclogitization proceeds given that the igneous plagioclase is pervasively replaced by clinozoisite kyanite and na rich plagioclase whereas kyanite diopside symplectites are confined to narrow rim zones we suggest that the development of these textures was controlled by the im mobility of different elements on different length scales the presence of hydrous minerals in the core of anhydrous plagioclase indicates that h2o diffusivity occurred on a mm scale by contrast the size of the anhydrous diopside kyanite and diopside garnet symplectites indicate that fe mg ca na diffusivity was limited to a 10s of m scale chemical potential relations calculated in the idealized ncash chemical system show that the clinozoisite kyanite albite intergrowths formed due to an increase of h2o to plagioclase whereas all other elements remained effectively immobile on the scale of this texture fluid conditions indicated by this texture span from virtually dry conditions ah2o 0 15 to h2o saturation and therefore does not imply that the rocks were ever fluid saturated calculations in the cmas and ncfmas systems show that the gabbro to eclogite transition is characterized by the growth of garnet diopsidic clinopyroxene and kyanite due to diffusion of ca na and mg fe along a cao na2o mgo feo chemical potential gradient developed between orthopyroxene and plagioclase compositional domains the anhydrous nature of the textures indicate that the gabbro to eclogite transition is not driven by hydration however increased h2o acts as a catalyst that increases diffusivity of all elements and rates of dissolution precipitation allowing the overstepped metamorphic reactions to occur our results show that crustal eclogite formation requires low h2o content confirming that true eclogites are dry rocks

recent seismicity and crustal stress field in the lucanian apennines and surrounding areas southern italy seismotectonic implications abstract we analyzed the instrumental seismicity of southern italy in the area including the lucanian apennines and bradano foredeep making use of the most recent seismological data base available so far p and s wave arrival times recorded by the italian national seismic network rsnc operated by the istituto nazionale di geofisica e vulcanologia ingv were re picked along with those of the saptex temporary array deployed in the region in the period 2001 2004 for some events located in the upper val d agri we also used data from the eni agip oil company seismic network we examined the seismicity occurred during the period between 2001 and 2006 considering 514 events with magnitudes m 2 0 we computed the v p v s ratio obtaining a value of 1 83 and we carried out an analysis for the one dimensional 1d velocity model that approximates the seismic structure of the study area earthquakes were relocated and for well recorded events we also computed 108 fault plane solutions finally using 58 solutions the most constrained we computed regional stress field in the study area earthquake distribution shows three main seismic regions the westernmost lucanian apennines characterized by high background seismicity mostly with shallow hypocenters the easternmost below the bradano foredeep and the murge with deeper and more scattered seismicity and finally the more isolated and sparse seismicity localized in the sila range and in the offshore area along the northeastern calabrian coast focal mechanisms computed in this work are in large part normal and strike slip solutions and their tensional axes t axes have a generalized ne sw orientation the denser station coverage allowed us to improve hypocenters determination compared to those obtained by using only rsnc data for a better characterization of the crustal and subcrustal seismicity in the study area