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

qualitative effects of local geology on damage pattern september 1997 registered the onset of a seismic sequence striking the umbria marche region central italy in which earthquakes up to intensity ix caused widespread damage with respect to villages settled in an intermountain basin near the epicentral area the resulting damage pattern is investigated to give a better understanding of future local ground motion sensitivity macroseismic data are collected and compared with the surface geology of 26 villages and hamlets within a restricted area among these 26 settlements seven individual groups of different geological conditions are discernible showing a gradual variation to the damage severity the greatest damage occurred within the basin in villages settled close to border faults significant damage also occurred at locations on the contact between fan debris with bedrock or alluvium in support of models existing in literature these observations show that strong shaking can be generated at the edge of basins

stress drops of the 1997 1998 colfiorito central italy earthquakes hints for a common behaviour of normal faults in the apennines stress drop estimates of moderate magnitude earthquakes in the umbria marche region in the northern apennines exhibit a large scatter for the two mw 5 7 and 6 0 main shocks of 26 september 1997 near colfiorito several papers resulted in stress drop estimates of 20 mpa but values as low as 2 3 mpa were proposed as well also for the largest aftershocks mw 4 estimates spread from 1 mpa up to values ten times larger we have critically revisited methods and data used in the literature we have specifically faced the trade off between source and propagation effects as we believe that it is responsible for a part of the large scatter to keep this trade off under control we have applied a methodology that combines the best fit of both source spectra after empirical green s function egf deconvolution and observed ground motion spectra finding that the results of the two different data sets converge independently at the same solution we have used ground motions observed in the colfiorito basin where an accelerograph and a co located seismological broad band station recorded three clusters of earthquakes in a broad magnitude interval 1 7 mw 6 0 we have found that the mainshock aftershock sequences result in stress drops of 2 5 mpa at mw 5 6 with an average tendency to decrease at smaller magnitudes where stress drop variability increases these findings confirm the source scaling recently assessed through empirical green s function deconvolution for another well monitored seismic sequence of normal faulting earthquakes which struck the city of l aquila in the central apennines in april 2009 the similar scaling law of the two areas suggests common mechanisms of stress release for the shallow normal faults in the apennines the propensity of smaller earthquakes to increase in variability with a tendency toward smaller stress drops may reflect an effect of fault strength heterogeneities for smaller size ruptures

geotechnical site characterisation in the umbria marche area and evaluation of earthquake site response in this research a site classification is proposed for the umbria marche area central italy based on geotechnical and geomorphological criteria two empirical techniques to evaluate site effects are used namely the generalised spectral inversion and the horizontal to vertical spectral ratio the soil transfer functions obtained by the two techniques are compared in order to capture the features common to each class and verify the accuracy of the classification we used strong ground motions recorded during the umbria marche seismic sequence september 1997 may 1998 and we selected 25 sites that were classified into four groups the results of the empirical techniques have also been tested using theoretical 1 d or 2 d methods that are commonly used to simulate linear soil behaviour the results expressed in terms of amplitude transfer functions are shown according to each soil class and confirm the consistency of the site characterisation the empirical techniques are efficient in detecting the fundamental frequency of vibration but seldom the higher harmonics conversely the peak amplitude of the transfer functions is not consistently determined especially for sites located in deep sedimentary basins where 2 d effects occur and simplified methods such as the horizontal to vertical spectral ratios hvsr or 1 d theoretical models frequently fail significant amplifications are also found for 2 d rock structures such as rock crests or cliffs

h v spectral ratios and array techniques applied to ambient noise recorded in the colfiorito basin central italy the colfiorito basin is a small intramountain depression in the southern section of the northern apennine chain that is filled with quaternary alluvial deposits the presence of soft alluvial deposits has significantly influenced the level of local damage that was caused by two major earthquakes m l 5 6 and 5 8 belonging to the swarm that started in september 1997 to verify the effects of the basin structure on the predominant frequency of seismic motion ambient noise measurements were carried out in the colfiorito basin during two experiments in may and july of 2002 the horizontal to vertical spectral ratios hvsrs were calculated for data collected at four profiles in the basin array techniques were applied to determine the wave types that composed the noise to estimate their apparent velocity and azimuth of propagation and to calculate a velocity dispersion curve from which a velocity depth structure was derived the data analysis shows a high amplification in the hvsr at low frequency this feature is common to most of the sites including the reference site and it is interpreted as being due to weather disturbances the peak frequencies of the spectral ratio calculated at the sites located in the center of the basin coincide with the theoretically estimated resonance frequencies the array averaged hvsr calculated for the array located in the middle of the plain has a pronounced peak at 0 9 hz this corresponds to the peak of the amplification function calculated on the basis of the velocity model deduced from the dispersion analysis the hvsr method is instead unsuitable for the prediction of the resonance frequencies of sediments in the sites where strong lateral variations of basement topography are present we measured apparent velocities in the range of 0 3 0 8 km sec by applying f k methods to array recordings these values are compatible with the predominance of surface waves in the noise as also confirmed by polarization analysis both rayleigh and love waves are present in the background seismic noise the results obtained by applying the spatial autocorrelation method to the vertical component of the ground motion recorded at a 240 m wide circular array deployed in the middle of the basin revealed the presence of rayleigh waves and f k methods combined with polarization techniques revealed the presence of polarized love waves the wave field analysis indicates two main propagation directions the first is around n100 e in the frequency band of 1 0 2 0 hz this radiation can be interpreted as being generated at the east southeast step borders of the basin the second main direction is around n300 e in the frequency band of 2 0 3 0 hz its source may be a 180 m deep depression located at the southwest corner of the basin

the relation between site amplification factor and surficial geology in central california abstract site amplification factors at frequencies of 1 5 3 6 and 12 hz were determined for 132 stations of the usgs seismic network in central california from coda waves of 185 local earthquakes in this area using a recursive stochastic inversion method we found that the site amplification at a station is systematically related to the geology underlying that station the site amplification is high for young quaternary sediments and decreases with increasing geologic age at all frequencies between 1 5 and 12 hz the rate of decrease varies with frequency where site amplification at low frequencies shows a faster rate of decrease with age than at higher frequencies to quantify the relation between site amplification factor and site geology the surface geology of station sites was classified into five groups namely 1 quaternary sediments 2 pliocene sediments 3 miocene through cretaceous sediments 4 franciscan formation and mesozoic granitic rocks and 5 pre cretaceous metamorphic rocks the station site amplification factors for each group were logarithmically averaged and the mean value was assigned to the median geologic age of that group a smooth power law relation was found between the mean site amplification and the median geologic age this relation provides a simple way of estimating site effect at a specific site with known surficial geology our site amplification factors were compared with magnitude station residuals determined by eaton 1990 for the same network a remarkable linear correlation was found between the logarithmic coda amplification factor and the magnitude station residual value confirming that the coda method provides an effective means of estimating site amplification factor comparison of our site amplification factor with strong motion results obtained from the loma prieta earthquake boore et al 1989 maley et al 1989 shakal et al 1989 chin and aki 1991 suggests that weak and strong motion site amplification factors correlate well in the region outside the epicentral source region beyond epicentral distances of about 50 km within the epicentral source region however the weak motion amplification factors estimated from coda waves do not agree with the observed for strong ground motion suggesting a nonlinear behavior at sediment sites these results together with studies on the correlation between weak motion site amplification and earthquake intensity borcherdt 1970 borcherdt and gibbs 1976 chavez garcia et al 1990 king et al 1990 demonstrate the importance of in situ determination of weak motion site amplification for seismic zonation

fault plane orientations of small earthquakes of the 1997 umbria marche italy seismic sequence from p wave polarities and rise times summary a two step technique has been developed with the aim of retrieving the fault plane orientation of a small magnitude earthquake the technique uses a set of non linear equations which relate the rise times of first p waves to source parameters source dimension l dip and strike of the fault and intrinsic qp at the first step of the technique the inversion of p polarities provides two fault plane orientations for each focal mechanism solution at the second step the inversion of rise times is carried out to retrieve l and qp by fixing and to the values of the fault plane orientation inferred at the first step a robust analysis based on the random deviates technique allows us to evaluate if one fault plane exists which systematically better fits data and can be considered the true fault plane a parameter is introduced to quantify the level of resolution of the true fault plane a probabilistic approach based on the assumption that errors on data are gaussian distributed allows us to a posteriori validate or reject the true fault plane the technique has been applied to 47 small earthquakes 1 3 ml 3 9 occurred below the town of sellano during the 1997 umbria marche central italy seismic crisis the strike of the inferred fault planes is generally along the apennine direction fault plane solutions can be mainly subdivided into two groups a first group of sw dipping faults and a second group of ne dipping faults these results agree with the present day knowledge of the fault systems in the area an average qp equal to 354 63 has been estimated in agreement with previous attenuation studies

slip distribution of the 1997 umbria marche earthquake sequence joint inversion of gps and synthetic aperture radar interferometry data 1 in september october 1997 a seismic sequence struck the southern part of the umbria marche region in central italy the three largest earthquakes took place on 26 september 0033 ut mw 5 7 09 40 gu mw 6 0 near colfiorito and on 14 october mw 5 6 near sellano we present a slip model for the main sequence over two separate fault planes we use previously published global positioning system gps and differential interferometric synthetic aperture radar dinsar data as well as new dinsar data covering the sellano event as input to a simulated annealing solution for the distribution of fault slip the combination of both types of geodetic data as well as the combination of sar interferograms from both ascending and descending satellite tracks allows us to make a more complete geodetically based assessment of the fault slip for these earthquakes for the solutions presented here we required the slip distribution to match the observed surface displacements while maintaining a total scalar seismic moment approximately equal to the seismologically inferred moments for this sequence we find the slip was concentrated in a zone at 4 5 5 km depth with a shallower tail extending to near the surface at the northern end of the colfiorito sequence for both the second colfiorito event and the sellano event individual patches were calculated with maximum slip of 2 m implying stress drops as high as 20 mpa coulomb stress calculations show that the coseismic slip distribution for the colfiorito events facilitated slip of the adjacent sellano earthquake

the 1997 umbria marche italy earthquake sequence a first look at the main shocks and aftershocks a long sequence of earthquakes six with magnitudes between 5 and 6 struck central italy starting on september 26 1997 causing severe damages and loss of human lives the seismogenic structure consists of a nw se elongated fault zone extending for about 40 km the focal mechanisms of the largest shocks reveal normal faulting with ne sw extension perpendicular to the trend of the apennines consistently with the quaternary tectonic setting of the internal sector of the belt and with previous earthquakes in adjacent regions preliminary data on the main shocks and aftershocks show that extension in this region of the apennines is accomplished by normal faults dipping at low angle 40 to the southwest and confined in the upper 8 km of the crust these normal faults might have reactivated thrust planes of the pliocene compressional tectonics the aftershock distribution and the damage patterns also suggest that the three main shocks ruptured distinct 5 to 15 km long fault segments adjacent and slightly offset from one another

investigation of a large scale mode of ocean atmosphere variability and its relation to tropical pacific sea surface temperature anomalies abstract by examining the linearly coupled atmospheric and oceanic signals related to interannual variability in sea surface temperatures and upper air wind fields a hemispheric scale ocean atmosphere teleconnection mode is isolated that is significantly correlated with equatorial pacific ssts 12 months later the interannual component of this teleconnection mode is related to a basin scale dipole in the upper air wind fields stretching across the extratropical pacific with additional anomalies extending from the eastern tropical pacific over north america and into the atlantic basin in addition it is related to variability in the sst field with warm anomalies found over the tropical subtropical western pacific as well as the equatorial eastern pacific also there are related cold anomalies over the extratropical central north pacific that extend down into the central subtropical tropical pacific diagnostic studies investigating the ocean atmosphere structure for this mode of variability indicate th

site response of strong motion stations in the umbria central italy region we used near field and regional records from 16 earthquakes m l 4 6 5 9 located in the epicentral area of the 1997 umbria marche sequence to estimate the site response of 40 strong motion stations the distribution of hypocenters covers a distance range from 5 to 100 km we estimated site amplification factors using two techniques namely a generalized spectral inversion method and horizontal to vertical component spectral ratios hvsrs of ground acceleration for the first approach we inverted observed spectral amplitudes for site q and source using a reference site since the site response estimated using hvsrs assumes that the vertical component of motion is amplification free we also separated source and site effects by inverting the vertical component of the acceleration spectra we found that although most of the stations do not show important amplifications on the vertical component a few of them have a significant vertical amplification at low frequencies f q representative of the s wave train shows a frequency dependence that can be approximated by the relation q s 31 2 f 1 2 between 0 3 and 9 5 hz however at high frequencies f 10 hz this dependence weakens and q s takes an approximately constant value of 438

crustal versus asthenospheric relaxation and post seismic deformation for shallow normal faulting earthquakes the umbria marche central italy case summary following a normal mode approach for a strati ed viscoelastic earth we investigate the eiects induced by shallow normal faulting earthquakes on surface post seismic vertical displacement and velocity at the surface when stress relaxation occurs in the crust or in the asthenosphere the modelled earthquake is a moderate one characteristic of some slowly deforming plate boundaries in the central mediterranean region we focus on the umbria marche central italy region where deep seismic re ection studies crop03 and the 1997 earthquake sequence clearly show a seismogenic layer decoupled from the lower crust by a sizeable transition zone accordingly the crust is subdivided into three layers an elastic upper crust a transition zone and a low viscosity lower crust the fault is embedded in the upper crust the layered viscoelastic structure of the crust and mantle imposes a pattern and scale on the modelled coseismic and post seismic deformation with a major contribution from the transition crustal zone and low viscosity lower crust stress relaxation in the mantle being negligible we show that signi cant vertical deformation rates of the order of 1 mm yr 1 could be expected for a shallow and moderate event such as the recent umbria marche earthquake for viscosity values of 10 19 and 10 18 pa s in the crustal transition zone and lower crust respectively

the 1997 umbria marche italy earthquake sequence relationship between ground deformation and seismogenic structure a field survey performed during the 1997 umbria marche earthquake sequence led us to recognize ground and pavement ruptures associated with the three largest shocks mw 5 7 the ruptures are concentrated in narrow bands that in part are on and near previously mapped high angle normal faults the geometry of the ground deformation is consistent with the ne trending extension indicated by cmt focal solutions of the mainshocks the distribution of aftershocks suggests that the three mainshocks occurred on 40 sw dipping normal faults geological investigations modelling of expected coseismic elevation changes and seismic data suggest that the surface deformation is not the direct result of primary rupture of faults at depth

the perugia italy earthquake of 29 april 1984 a microearthquake survey a field study after the perugia earthquake of 29 april 1984 provided more than 300 well recorded events concentrated within two parallel clusters separated by 2 km and trending along the apenninic direction the length of the aftershock area is 14 km focal depths being shallower than 8 km relocation of the main event places the epicenter at the southern end of the aftershock zone suggesting a rupture propagation from se to nw most focal mechanisms are consistent with normal faulting the spatial distribution of seismicity suggests that the gubbio normal fault was activated during the main shock this earthquake together with the norcia 1979 and the abruzzi 1984 shocks is typical of the extension in the high apennines generated by the flexure of the mountain chain in response to regional compression the parma 1983 event a thrust belongs to the compres sion zone at the eastern flank of the chain these results are consistent with the ew continental collision along the apennines

on the characteristics of local geology and their influence on ground motions generated by the loma prieta earthquake in the san francisco bay region california strong ground motions recorded at 34 sites in the san francisco bay region from the loma prieta earthquake show marked variations in characteristics dependent on crustal structure and local geological conditions peak horizontal acceleration and velocity inferred for sites underlain by rock generally occur on the transverse component of motion they are consistently greater with lower attenuation rates than the corresponding mean value predicted by empirical curves based on previous strong motion data theoretical amplitude distributions and synthetic seismograms calculated for 10 layer models suggest that bedrock motions were elevated due in part to the wide angle reflection of s energy from the base of a relatively thin 25 km continental crust in the region characteristics of geologic and geotechnical units as currently mapped for the san francisco bay region show that average ratios of peak horizontal acceleration velocity and displacement increase with decreasing mean shear wave velocity ratios of peak acceleration for sites on soil alluvium fill bay mud are statistically larger than those for sites on hard rock sandstone shale franciscan complex spectral ratios establish the existence of predominant site periods with peak amplifications near 15 for potentially damaging levels of ground motion at some sites underlain by alluvium and fill bay mud average spectral amplifications inferred for vertical and the mean horizontal motion are respectively 1 1 for sites on the franciscan complex kjf 1 4 1 5 for sites on mesozoic and tertiary rocks tmzs 2 1 2 0 for sites on the santa clara formation qts 2 3 2 9 for sites on alluvium qal and 2 1 4 0 for sites on fill bay mud qaf qhbm these mean values are not statistically different at the 5 significance level from those inferred from previous low strain data analyses suggest that soil amplification and reflected crustal shear energy were major contributors to levels of ground motion sufficient to cause damage to vulnerable structures at distances near 100 km in the cities of san francisco and oakland

the stratigraphic and geochemical record of playa cycles monitoring a pangaean monsoon like system triassic middle keuper s germany abstract the combination of high resolution stratigraphy with high resolution geochemistry allowed monitoring the cyclicity of a playa system in two dimensions time and space the playa cycles of the middle upper triassic steinmergel keuper located in southern germany were studied both in terms of lateral facies shift variations and long term cyclic patterns the lateral variation was expressed by investigating a time equivalent transect that spanned the kieselsandstein horizon within a 130 km distance from marginal to mid playa position whereas the long term cyclic pattern was investigated in core malschenberg where a time record of ca 5 106 years was encountered mudstone dolomite cycles with dolomites representing the wet and mudstones the dry phases reflect cyclic playa lake level changes indicating varying intensities of monsoon like circulation moisture transport from the tethys ocean into the german basin is implied by 18o depletion trends of isochronous dolomite beds from the margin to mid playa position suggesting dominantly rayleigh like circulation patterns distinct covariance of 18o 13c is used as indicator of lake level stands the k al curve with inverse covariation compared to 18o reflects fluctuating weathering conditions on the fan and the vindelician high a hierarchic cycle stacking pattern composed of metre scale to tens of metre cycles is interpreted to be a result of changing pangaean monsoon like intensities in the milankovitch frequency band spectral analysis shows that the power spectra are dominated by precession and eccentricity

lakes as paleoseismic records in a seismically active low relief area rieti basin central italy abstract small lakes in low relief areas are atypical candidates for studies on paleoseismicity but their sediments can contain seismically induced event layers seismites generated through strong ground shaking sediment transport hydrological reorganization and or changes in groundwater chemistry and flow lakes lungo and ripasottile are shallow lakes

a stable isotope and organic geochemical study of the relationship between the anthracosia shale and kupferschiefer mineralization se poland abstract there are at least two mineralized horizons that occur in association with the rotliegendes red bed sediments of central europe the first is the well known kupferschiefer at the top of the rotliegendes the second is the upper anthracosia shale of the north sudetic depression in the middle part of the red bed section in the present study upper anthracosia shale has been investigated by use of various geochemical methods and results have been compared with those obtained from previous studies of the kupferschiefer both mineralized horozins show the same organic geochemical phenomena and isotope variations interpreted as a result of post depositional migration of mineralizing fluids originating from red bed sediments both organic rich horizons acted as reducing traps for migrating metals therefore the processes that led to the base metal emplacement in the ore grade areas of the kupferschiefer are shown to have an universal character also with regards to the upper anthracosia shale the patchy occurrence of cu mineralization in the anthracosia shale horizons is related to the fault controlled movement of mineralized fluids the cu dominated composition of mineralization is explained by the simplicity of the base metal source preferentially rotliegendes formation waters of mostly meteoric origin new data on the isotopic compositions of c in organic materials and of c and o in carbonates combined with an organic geochemical study of a non mineralized section through the lower anthracosia shale provide information on the sedimentary environment and conditions during diagenesis the changes during sedimentation of the lower anthracosia shale are related to subsidence the thickness of water column sedimentation rate redox potential and paleoclimatic conditions in the center of the profile from the lower anthracosia shale the amounts of calcite and organic carbon concomitantly increase which can be explained by the development of anoxic bottom waters due to enhanced subsidence of the basin the water column might have temporarily increased resulting in increased biomass production and better preservation of organic material in the lower and the upper parts of the profile the biomass production was significantly lower due to increased rate of sedimentation and probably decreasing water column

hydrothermal alteration of the ediacaran volyn brest volcanics on the western margin of the east european craton abstract the ediacaran continental flood basalts and associated tuffs were studied to identify and quantify alteration processes by means of xrd and chemistry supplemented by mossbauer and ftir spectroscopies petrography oxygen and iron isotopes k ar dating and organic geochemistry two superimposed alteration processes were identified the ediacaran hydrothermal alteration induced by meteoric waters heated and put in motion by the cooling basalt and the caledonian and or variscan potassic alteration the degree of basalt alteration was quantified using as an index the sum of primary minerals in the bulk rock the sequence of minerals dissolved and crystallized during the hydrothermal alteration was established the alteration resulted in the loss of ca dissolution of plagioclases compensated by the gain of water and mg crystallization of clays and proceeded from the edges of the basalt flows in an oxidizing environment evidenced by the increasing amount of hematite and fe3 fe2 ratio of the bulk rock cyanobacteria were active in the hydrothermal system most probably responsible for the measured negative 56fe values and more reducing conditions at the stage of intense alteration chlorophaeite palagonite following quartz as the earliest petrographically identifiable basalt alteration product was found to vary systematically from fully isotropic to birefringent the chlorophaeite was identified as a mixture of fe montmorillonite and fe saponite identical with griffithite and oxysmectites probably preceded by a finer grained ferrosaponite at the isotropic stage ree content of chlorophaeite indicates basaltic volcanic glass sideromelane as the major source of material ree in clays are contained mostly in the dioctahedral smectite while in the bulk rock mostly in phosphates the smectite characteristics and mg enrichment are indicative of the hydrothermal basalt alteration process which perhaps was dominant also on mars both mineral and chemical composition of tuffs vary continuously from basaltic to felsic the latter close to the measured rhyodacite composition dominated by quartz and feldspars the basaltic tuffs resemble the most altered basalts but contain also abundant albite and chlorite indicative of higher alteration temperatures up to 220 c tuff composition indicates stronger component of felsic volcanism in the trap formation than evidenced by the preserved bodies of effusive rocks

recent tectonic evolution and present stress in the northern apennines italy the present day stress field and its recent tectonic evolution in the northern apennines are reconstructed from borehole breakout analysis and focal mechanisms of crustal earthquakes and through the comparison with paleostress data we have considered 86 wells for breakout analysis with depths down to 6 7 km 125 fault plane solutions of crustal earthquakes with m 5 that occurred between 1988 and 1995 in the northern and central apennines and data of stronger earthquakes m 6 reported in other studies the tyrrhenian coastal region and the apenninic belt are characterized by shmin direction mainly trending ne sw with predominantly normal fault plane solutions along the outer front of the belt and the adriatic offshore shmin is oriented nw se and focal solutions are thrust or strike slip with maximum compression around ne sw conversely south of 43 n breakouts evidence an orthogonal direction of horizontal compression nw se following the southern apennine trend where a widespread ne sw extension was recognized by previous investigations comparing these results to the recent tectonic evolution inferred from structural geology we argue that the extension compression pair characteristic of the post tortonian evolution of the mountain belt has been migrating in time from late miocene to present only in the northern sector of the arc whereas the southern sector underwent a generalized extension at least since middle pleistocene the striking correspondence between the active compression front and the region with evidence of a remnant subducted slab suggests that the migrating extension compression pair has been controlled by progressive retreat of the slab

detailed evaluation of site response estimation methods across and along the sedimentary valley of volvi euro seistest using records from the euro seistest area near thessaloniki greece we studied empirically the amplification effects of a sedimentary valley one of the main advantages of this site is the very detailed knowledge of the near subsurface structure due to exhaustive geophysical and geotechnical measurements and data analyses jongmans et al 1998 the uniqueness of the seismological data set is the very dense network 31 stations were installed perpendicular and parallel to the valley axis with minimum interstation distances of 250 m the mean ampli fications along both axes estimated from 13 local events were imaged using the traditional spectral ratio technique variations of the mean amplifications due to the choice of different data subsets were tested by the use of up to 89 local events supplemented by four teleseismic events offering good low frequency resolution results obtained using the traditional spectral ratio technique were compared with results from a generalized inversion technique the h v ratio technique a coda wave technique and nakamura s technique advantages and disadvantages of each method are outlined especially from a practical point of view

geochemistry and organic petrography of cretaceous sediments of the calabar flank southeastern nigeria abstract detailed bulk geochemistry and organo petrography of outcrop cretaceous sediments with no significant effects of weathering from the calabar flank southeast nigeria were performed to understand the organic carbon source accumulation and degradation and paleo climatic paleoceanographic and paleoenvironmental conditions in west africa during early cretaceous aptian to maastrichtian times this study was based on microscopic elemental analyses organic carbon nitrogen iron and sulphur rock eval pyrolysis and carbon isotope analyses in general the calabar flank shales are characterised by highly variable total organic carbon toc contents which range between 0 1 in aptian albian mfamosing limestone and 9 9 in the awi formation sediments the organic matter om is a mixture of immature to early mature marine and terrigenous om of types iii and iv this is indicated by low hydrogen indices hi value 10 190 mg hc g toc tmax 417 460 c vitrinite reflectance ro 0 39 0 62 ro low to high c n ratios 3 4 1158 0 and high amounts of terrigenous macerals vitrinite inertinite based on carbon isotope c n ratios and sulphate reduction index sri om degradation up to 70 sri 2 5 is most pronounced for shales deposited in a marine environment the geochemical and petrographic data indicate that local factors such as low bioproductivity down slope transport and redeposition of sediments from a fluvial deltaic basin to nearshore facies shallower oxic and mildly oxygen deficient environments humid arid paleogeographic conditions specifically controlled the amount and quality of the om during aptian mastrichtian stages where marine sediments have been assumed to be deposited during the global anoxic events therefore the order of the main factors controlling om content in sediments are input of terrigenous material transported from the land low om productivity by marine photoautotrophs low preservation

the seismic coda site effects and scattering in alluvial basins studied using aftershocks of the 1986 north palm springs california earthquake as source arrays abstract we use single station recordings of widely distributed earthquake sources to identify heterogeneities in the earth9s crust that scatter energy into the early part of the observed s wave codas we assume that ray theory accurately describes the propagation of body waves from the earthquake sources to the scatterers but we assume no propagation mechanism between the scatterers and the seismic station a grid of hypothetical scatterers is assumed to cover the earth9s surface and the strength of each scatterer is determined by an iterative inversion method our data are recordings of aftershocks of the 1986 north palm springs earthquake recorded at a seismic station in the coachella valley smp and at a station in the morongo valley smc the technique is applied separately to each horizontal component of motion at each station we identify a particular spot at the northwest edge of the quaternary alluvium in the coachella valley that scatters waves into the s coda observed at smp 8 km distant in the valley the geologic structure that causes the strong scattering seems to be the basin edge structure rather than the mountainous terrain 3 km farther west the early coda at smc is dominated by scattering within a few kilometers of smc either in the basin itself or in the morongo valley fault zone this study shows that laterally propagating waves are sometimes observable in the early coda casting doubt on the use of 1 d techniques for estimating site responses the northwest edge of the coachella valley seems to be an especially strong scatterer of incident waves if other basins have similar loci of strong scattering perhaps these places can be identified using microearthquake seismograms and used to predict strong ground motions in the basins

geodetic and seismologic evidence for slip variability along a blind normal fault in the umbria marche 1997 1998 earthquakes central italy summary we analysed elevation changes induced by the 1997 1998 umbria marche central apennines italy earthquakes we employed data from a first order geodetic levelling line measured in 1951 1992 and 1998 the line bears a record of pre seismic and coseismic strains associated with the causative fault of the 1997 september 26 09 40 mainshock mw 6 0 a first level analysis performed under the assumption of slip homogeneity of coseismic slip shows misfits that cannot be reduced simply by altering the fault size and geometry a more detailed analysis based on a distribution of coseismic slip obtained from broad band seismograms provides a better fit and is in agreement with 1951 1992 elevation changes interpreted as precursory slip by previous investigators the levelling data sets new constraints on the location extent dip and depth of the fault in full agreement with seismological evidence and images from sar interferometry the data show no evidence for slip in the uppermost 3 km of the crust suggesting that a major and widely recognized normal fault that exists in the area is no longer active and showing a tendency of present tectonic strains to revert the current topographic setting

a consistent poleward shift of the storm tracks in simulations of 21st century climate 1 a consistent poleward and upward shift and intensification of the storm tracks is found in an ensemble of 21st century climate simulations performed by 15 coupled climate models the shift of the storm tracks is accompanied by a poleward shift and upward expansion of the midlatitude baroclinic regions associated with enhanced warming in the tropical upper troposphere and increased tropopause height the poleward shift in baroclinicity is augmented in the southern hemisphere and partially offset in the northern hemisphere by changes in the surface meridional temperature gradient the poleward shift of the storm tracks also tends to be accompanied by poleward shifts in surface wind stress and precipitation and a shift towards the high index state of the annular modes these results highlight the integral role that the storm tracks play in the climate system and the importance of understanding how and why they will change in the future

ground motion amplification geology and damage from the 1989 loma prieta earthquake in the city of san francisco main shock and aftershock accelerograms from the loma prieta earthquake sequence are analyzed to study relative ground amplification at sites in the city of san francisco main shock spectra are estimated for those stations that recorded only aftershocks by comparing their records to those from stations that recorded both the ratios of the spectra with respect to a stable bedrock station located at fort mason show distinct spectral shapes that are strongly correlated with the rock type underlying the site earthquake damage is quantified using estimates of the modified mercalli intensity at the recording sites and safety tags issued by the city of san francisco building department these intensities are compared with ground amplification in three frequency bands and with the intensities at the same sites from the 1906 san francisco earthquake there is sufficient correlation to show that site amplification is one of the controlling factors in damage distribution

orographic precipitation and air mass transformation an alpine example a case of orographic precipitation in the alps on 20 september 1999 was studied using several models along with rain gauge and radar data the objective of the study is to describe the orographic transformation of an air mass including multi scale aspects several new and some conventional diagnostic quantities are estimated including drying ratio precipitation efficiency buoyancy work condensed water residence time parcel changes in heat moisture and altitude and dominant space and time scales for the case considered the drying ratio was about 35 precipitation efficiency values are ambiguous due to repeated ascent and descent over small scale terrain the sign of buoyancy work changed during the event indicating a shift from stratiform orographic to weak convective clouds cloud water residence times are different for the two mesoscale models 400 compared to 1000 s due to different cloud physical formulations the two mesoscale models agree that the dominant spatial scale of lifting and precipitation is about 10 km smaller than the scale of the main alpine massif trajectory analysis of air crossing the alps casts doubt on the classic model of fohn few parcels exhibit classic pattern of moist ascent followed by dry descent parcels that gain latent heat descend only briefly before rising into the middle troposphere parcels that descend along the lee slope originate in the middle troposphere and gain little or even lose latent heat during the transit as parcels seek their proper buoyancy level downstream a surprising scrambling of the air mass occurs radar data confirm the model prediction that the rainfall field is tightly controlled by local terrain on scales as small as 10 km rather than the full 100 km cross alpine scale a curious pulsing of the precipitation is seen indicating either drifting moisture anomalies or weak convection copyright 2003 royal meteorological society

the 2009 l aquila central italy mw6 3 earthquake main shock and aftershocks 1 a m w 6 3 earthquake struck on april 6 2009 the abruzzi region central italy producing vast damage in the l aquila town and surroundings in this paper we present the location and geometry of the fault system as obtained by the analysis of main shock and aftershocks recorded by permanent and temporary networks the distribution of aftershocks 712 selected events with m l 2 3 and 20 with m l 4 0 defines a complex 40 km long nw trending extensional structure the main shock fault segment extends for 15 18 km and dips at 45 to the sw between 10 and 2 km depth the extent of aftershocks coincides with the surface trace of the paganica fault a poorly known normal fault that after the event has been quoted to accommodate the extension of the area we observe a migration of seismicity to the north on an echelon fault that can rupture in future large earthquakes

seismicity seismotectonics and seismic hazard of italy abstract a first generation of probabilistic seismic hazard maps of the italian country are presented they are based on seismogenic zoning deriving from a kinematic model of the structural tectonic units and on an earthquake catalogue with the foreshock and aftershock events filtered out the following ground motion parameters have been investigated and mapped using attenuation equations based on strong motion recordings of italian earthquakes peak ground acceleration and velocity arias intensity strong motion duration and the pseudovelocity and pseudoacceleration spectral values at 14 fixed frequencies both for the vertical and the largest horizontal component a poissonian model of earthquake occurrence is assumed as a default and the hazard maps are presented in terms of ground motion values expected to be exceeded at a 10 probability level in 50 years return period 475 years according to the requirement of eurocode 8 for the seismic classification of national territories as well as in terms of exceedance probabilities of selected ground motion values finally as a tentative study the use of hybrid methods implementing both seismogenic zones and structures renewal processes including earthquake forecasting and the influence of site effects as the basis for the planning of earthquake scenarios were explored

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

polycyclic aromatic hydrocarbons pahs in late eocene to early pleistocene mudstones of the sylhet succession ne bengal basin bangladesh implications for source and paleoclimate conditions during himalayan uplift abstract distribution and possible sources of polycyclic aromatic hydrocarbons pahs have been investigated in 23 late eocene to early pleistocene mudstones from the sylhet succession of the northeastern bengal basin bangladesh paleoclimatic conditions in the southern himalaya region throughout the himalayan uplift were reconstructed based on combustion derived pahs and aromatic land plant derived biomarkers phenanthrene fluoranthene fla pyrene py benz a anthracene baan chrysene triphenylene chry tpn benzofluoranthenes bflas benzo e pyrene bepy benzo a pyrene bapy perylene pery indeno 1 2 3 cd pyrene inpy benzo ghi perylene bghip coronene cor and retene ret were the identified pahs fla fla py ratios 0 5 and inpy inpy bghip 0 2 from almost all sylhet samples suggest occurrence of natural wildfires low contents of baan and bapy indicate decomposition by long exposure to sunlight before sedimentation or early diagenetic weathering increased cor inpy and bghip contents suggest occurrence of larger high temperature wildfires correlation coefficients of the pahs and p values for statistical hypothesis testing showed that the positive and negative correlations within the pahs may be indicative of high or low temperatures in wildfires fungi derived pery showed negative correlations with py r 0 67 p 4 6 10 4 and fla r 0 56 p 5 0 10 3 but not with cor bflas inpy and bghip based on the correlation coefficients for all pahs and their p values five statistical groups py fla cor bflas inpy bghip baan chry tpn bapy pery and ret were recognized these groups are probably correlated with origins and depositional processes according to the results the sylhet succession was deposited in three differing paleoclimatic regimes 1 first phase late eocene to early miocene early to middle stage of himalayan uplift high contents of combustion derived pahs fla py and bepy significant gymnosperm derived ret and low pery abundances in the jaintia and barail groups indicate arid climatic conditions although wildfires could often occur 5 or 6 ring combustion pahs cor inpy and bghip contents are low suggesting that the wildfires were relatively low temperature 2 second phase middle to late miocene middle to late stage of himalayan uplift combustion derived pahs and fungi derived pery were dominant in the surma group the climate was arid to humid and seasonal with a dry season giving conditions suitable for combustion abundant fla bflas bepy cor inpy and bghip imply high temperatures in large wildfires however frequency of the wildfires decreased because of wet climate 3 third phase late miocene to pleistocene late stage of himalayan uplift moderate to high pery contents and low fla py and bepy abundances in the tipam and dupitila groups indicate establishment of more humid climate inpy bghip cor bflas and bapy were predominant intensified humid and seasonal climate arising from the himalayan monsoon decreased the incidence and frequency of general wildfires but increased the ratio of large to small wildfires

age and temperature constraints on metamorphism and exhumation of the syn orogenic metamorphic complexes of northern apennines italy abstract the apennine range is a young convergent orogen that formed over a retreating subduction zone syn orogenic metamorphic rocks are exposed in the mid tuscan ridge tuscan coast and tuscan archipelago and provide information about processes of continental subduction and exhumation associated with accretion and retreat apatite and zircon fission track analyses were applied to some of these syn orogenic metamorphic rocks the new low temperature thermochronological data helped to constrain the timing of the metamorphic peak and the age and modality of exhumation of these rocks that were structurally buried at 20 to 40 km depth during the main tectonogenic phase of the northern appenine belt in the giglio and elba islands and in the monti dell uccellina along the coast minimum ages of partially reset zircon samples yielded a first time constraint on the late oligocene age of the metamorphic peak the ca 27 ma obtained at the monti dell uccellina is coeval to that found in the alpi apuane located at the northern termination of the mid tuscan ridge the data from the tuscan archipelago point to a slightly older age in the monti pisani south of the alpi apuane and in the argentario promontary along the coast south of the monti dell uccellina completely reset zircon samples but composed by different populations were behaving as multiple thermochronometers and confirm the already proposed isothermal nature of the exhumation occurred after the metamorphic peak zircon p1 peak indicated that at 13 10 ma rocks were already at shallow crustal levels

high density macroseismic survey in urban areas part 2 results for the city of rome italy high density macroseismic surveys were carried out in rome following both the 14 october 1997 m w 5 6 i 0 viii mcs and the 26 march 1998 m w 5 3 i 0 vi vii mcs umbria marche central italy earthquakes the aim of the work was to investigate the relationship between intensity and local geology for the modern urban area of rome an issue yet to be examined in contemporary times intensity data for both earthquakes were correlated with near surface geology the results show a statistically significant amplification in holocene alluvial deposits in particular we found one degree of difference in mcs intensity between hard rock and recent alluvium formations furthermore the distribution of the earthquake effects in alluvium filled valleys was studied as a function of the shape ratio h l of the alluvial basins in the tiber river valley higher effects were found to be concentrated within a 150 m wide band along the bedrock alluvium surface contact suggesting the occurrence of an edge effect surprising results were observed in the minor alluvial valleys which displayed the strongest effects in terms of shaking the narrowest valleys width

active tectonics in the central apennines and possible implications for seismic hazard analysis in peninsular italy abstract the central apennines fault system cafs of peninsular italy overprints earlier structures of a neogene fold and thrust belt and includes segments characterized by diffuse seismicity distributed within a nnw sse trending zone 50 60 km wide the system has been analysed by means of morphotectonic and structural analysis of exposed active fault segments the resulting fault structure consists of an interconnecting network of roughly n s trending left lateral strike slip segments and mostly nw se oriented transtensional to normal faults evidence for recent activity of cafs structures is provided by faulted middle pleistocene holocene deposits including 30 40 ka old pyroclastites and 40 ka old palustrine sediments fresh scarps in both bedrock and late quaternary continental deposits and decametric lateral offsets locally affecting the post wurmian drainage pattern of the area the regional stress field responsible for the development and evolution of the cafs as inferred from fault slip data is characterized by a nw se compression and by a ne sw extension the cafs pattern and its present day kinematics have been related to left lateral strike slip motion on north south trending crustal faults the existence of deep seated strike slip faults in the central apennines has implications for seismic hazard analysis motion along these structures suggests in fact that coseismic surface faulting is distributed and that cumulative displacements include normal transtensional and strike slip components the seismogenic potential of cafs structures can therefore be best described by multiple rupture models and be better analysed in terms of partial contributions of lower rank features constituting congruent structural associations within the system

the application of predictive modeling techniques to landslides induced by earthquakes the case study of the 26 september 1997 umbria marche earthquake italy abstract during september and october 1997 an earthquake sequence of moderate magnitude struck the umbria and marche regions central italy as a consequence of the most severe shocks several landslides were triggered on bedrock calcareous debris and sandy clay deposits the landslide inventory collected in the field and by aerial photo interpretation provided an opportunity to test the accuracy of existing predictive relations for landslide hazard zoning and to formulate new ones shallow soil slides and debris slides were selected to verify the prediction performance of the methods which are based on a simplified model geotechnique 15 1965 139 that calculate landslide displacements during cyclic seismic loading rock falls were modeled using a different approach to produce an empirical predictive rule for determining the probability of detachment of blocks when landslides occur along pre existing or newly formed failure surfaces the arias intensity and destructiveness potential are the strong ground motion parameters that best relate to displacements the predictive relation proposed for rock falls evaluates the probability of occurrence as a function of the slope angle and the peak ground acceleration pga

complex normal faulting in the apennines thrust and fold belt the 1997 seismic sequence in central italy a long sequence of moderate magnitude earthquakes 5 m 6 struck central italy in september and october 1997 at the end of the sequence a year later the seismogenic area extends for about 60 km along the apennines the analysis of historical seismicity suggests that this seismic sequence filled a 700 year gap in this portion of the chain other historical sequences in the same area are characterized by prolonged seismic release on adjacent fault segments probably due to the in volvement of shallow and complex structures inherited by the compressive tectonics the distribution of seismicity and the fault plane solutions show that the extension in this region is accomplished by normal faults dipping at relatively low angles 40 to the southwest the focal mechanisms of the largest shocks reveal normal faulting with extension perpendicular to the apenninic chain northeast southwest consistently with the quaternary tectonics of the internal sector of the northern apen nine belt and with previous earthquakes in adjacent regions three mainshocks oc curred on distinct 5 to 10 km long fault segments adjacent and slightly offset be tween each other high quality aftershock locations show that seismicity is confined within the sedimentary mesozoic cover in the upper 8 km of the crust and that most of the aftershocks are shallower than the largest shocks which nucleated at 6 km depth faults evidenced by aftershock locations have a planar geometry and show increased complexity toward the surface most of the aftershock focal mechanisms are dominated by normal faulting several strike slip events occurred at shallow depths reactivating portions of pre existing thrust planes that segment the normal fault system the spatiotemporal evolution of seismicity shows a peculiar migration of hypocenters along the strike of the main faults with multiple ruptures and the activation of fault segments before the occurrence of the main rupture episodes

seismological geological and geophysical constraints for the gualdo tadino fault umbria marche apennines central italy abstract the april 3 1998 mw 5 1 gualdo tadino earthquake central italy was the last significant event in the 6 month long umbria marche seismic crisis this event and its aftershocks occurred in an area where active faulting produces no striking geological and geomorphological effects in this study we investigated the ruptured fault using detailed seismological data and a re processed and re interpreted seismic reflection profile aftershock location and focal mechanisms were used to constrain the geometry and kinematics of the ruptured fault and a comparison was made with the subsurface image provided by the seismic profile we found that the 1998 gualdo tadino earthquake occurred on a wsw dipping normal fault with a length of about 8 km and a relatively gentle dip 30 40 confined between 3 5 and 7 km in depth kinematics of the mainshock and aftershocks revealed a ne trending extension in agreement with the regional stress field active in the northern apennines belt the mw 5 1 earthquake originated above the top of the basement and ruptured within the sedimentary cover which consists of an evaporites carbonates multilayer we hypothesised that the active fault does not reach the surface blind normal fault

site effects as inferred from damage severity observation a long seismic sequence affecting the umbria marche region central italy started on september 26 1997 earthquakes with intensities up to ix mcs caused diffused damage over a large area the resulting damage pattern is investigated for villages settled in an intermountain basin near the epicentral area macroseismic data are collected and compared with the surface geology for 15 villages and hamlets within a restricted area among these 15 settlements six individual groups are discernable showing a gradual variation of the damage severity such abrupt damage variation inside a relatively small area is influenced by modest scale lithological transitions in particular major effects occurred in those villages settled in the sedimentary basin close to border faults safest sites resulted to be those settled on bedrock and on the alluvial plane far from the edge these observations support models existing in literature which claim that edge effects and the generation of diffracted waves in soft basins can contribute to a stronger shaking

analysis of ground deformation detected using the sbas dinsar technique in umbria central italy ground deformation affecting the umbria region central italy in the 9 year period from 1992 to 2000 was investigated through multi temporal differential synthetic aperture radar interferometry dinsar for the purpose the small baseline subset sbas technique was adopted which allows studying the temporal evolution of the detected deformation at two spatial scales a low resolution regional scale and a full resolution local scale for the analysis sar data acquired by the european remote sensing ers 1 2 satellites along ascending and descending orbits were used the detected deformation was analysed to investigate its relevance to geophysical geomorphologic and human induced processes that may result in hazardous conditions to the population of umbria low resolution deformation data were used to i determine the amount of displacement caused by the umbria marche earthquake sequence from september 1997 to april 1998 in the foligno area ii determine the number and percentage of the known landslides that can be monitored by the dinsar technology in the investigated area and iii identify and measure subsidence induced by exploitation of a confined aquifer in the valle umbra results indicate that earthquakes moved through the foligno area westwards up to 3 9 cm and with an uplift reaching 1 7 cm intersection in a gis of the low resolution deformation maps with a detailed landslide inventory map allowed the determination that the portion of landslides that can be monitored by the sbas dinsar technique in umbria ranges from 2 7 to 3 4 and the percentage of the total landslide area ranges from 10 4 to 12 8 in the valle umbra a dependency was found between the time and the amount of detected ground deformation and the record of water withdrawal the full resolution deformation data were used to investigate the movement of the ivancich landslide in the assisi municipality joint analysis of the spatial and the temporal characteristics of the ground displacement allowed the formulation of a hypothesis on the landslide geometry and deformation pattern

the response of orographic precipitation over idealized midlatitude mountains due to global increases in co2 abstractthe sensitivity of stratiform midlatitude orographic precipitation to global mean temperature is investigated through numerical simulations as a step toward understanding the relative influence of thermodynamic and dynamical processes on orographic precipitation simple idealizations of earth s major north south mountain chains are considered the individual terrain elements occupy four islands equally spaced around the northern hemisphere of a planet otherwise covered by ocean although these mountains have very little influence on the sensitivity of the zonally averaged precipitation to changes in global mean surface temperature the precipitation on the windward slopes of the ridges is highly sensitive to such changes when the ridges run between 40 and 60 n the windward slope hydrological sensitivity exceeds the clausius clapeyron scaling of about 7 k 1 over the northern half of the barrier leading to substantial precipitation changes the annual accumulated orographic precipitation is mo

distribution of ground motion intensity inferred from questionnaire survey earthquake recordings and microtremor measurements a case study in christchurch new zealand during the 1994 arthurs pass earthquake the areal distribution of seismic ground motion intensity in the city of christchurch new zealand during the 1994 arthurs pass earthquake ml 6 6 was evaluated using an intensity questionnaire together with local site amplifications inferred from seismic recordings and microtremors in order to estimate the intensity in parts of the city where no intensity data were available intensity data were compared to relative levels of shaking determined from both weak motion and microtremor recordings weak ground motion amplification factors were determined using ratios of ground accelerations at five sediment sites with respect to a rock site microtremor amplification factors were determined from horizontal to vertical spectral ratios at a 1 km spacing throughout the city a positive correlation between weak motion and microtremor amplification factors allowed extrapolation of microtremor amplification to estimated mm intensity emmi emmi ranged from 3 to 6 and was consistent with the questionnaire intensity and geological conditions and showed detailed information on the areal distribution of ground motion intensity in the city

phenyldibenzofurans and phenyldibenzothiophenes in marine sedimentary rocks and hydrothermal petroleum abstract the phenyl derivatives of dibenzo b d furan and dibenzo b d thiophene so far not reported in geological samples have now been identified in some sedimentary rocks bitumen and hydrothermal petroleum through a comparison of their retention times and mass spectra with those of authentic standards all four possible positional isomers were detected for each phenyldibenzo b d furan phdbf and phenydibenzo b d thiophene phdbt their elution sequence is 1 4 2 and 3 phenyldibenzo b d furan and 1 4 2 and 3 phenyldibenzo b d thiophene on apolar stationary phases in contrast to phenyldibenzofurans the distributions of the thiophene series is controlled mainly by the organic matter maturity in the most mature samples 4 2 and 3 phdbts prevail over 1 phdbt while less mature samples contain mainly 4 phdbt or 1 phdbt and 2 3 phdbts occur at comparable concentrations however in samples of low maturity in addition to the phenyldibenzo b d thiophene c 18 h 12 s series other structural isomers of c 18 h 12 s possessing very similar mass spectra were detected these are likely to be either naphthylbenzo b thiophenes and or phenylnaphtho b thiophenes phdbfs and phdbts are likely to be intermediate products in the formation of more condensed heterocyclic polycyclic aromatic compounds like triphenyleno 1 12 bcd thiophene and triphenyleno 1 12 bcd furan and benzobisbenzofurans and benzobisbenzothiophenes which are commonly detected in geological samples

insights into bedrock paleomorphology and linear dynamic soil properties of the cassino intermontane basin central italy abstract seismic amplifications are dictated by the depth of the bedrock and the stratigraphy and dynamic properties of the soil deposits quantifying these properties together with their uncertainty is a necessary task to perform a reliable assessment of the seismic risk at an urban scale in this paper a multidisciplinary analysis is presented where information of different nature is combined borehole logs geophysical geological and geotechnical surveys are interpreted with the aid of analytical numerical and geostatistical techniques to characterise the complex shape of the bedrock and the linear dynamic properties of the sedimentary deposits filling the cassino basin a quaternary intermontane basin located in central italy the regional and local seismic hazard is firstly identified with geological surveys that reveal an active seismogenic fault capable of producing earthquakes with estimated magnitudes up to 6 7 6 8 boreholes reaching depths variable up to a maximum of 180 m and microtremor measurements revealing the sharp impedance contrast at the transition between the sedimentary arenaceous bedrock and the soft quaternary infilling are combined to identify the depth of the bedrock and the linear dynamic properties of soil deposits these are one of the key factors governing the propagation to the ground level of seismic waves and their assessment represents the first step for the seismic hazard characterisation of the plain

role of the brittle ductile transition on fault activation abstract we model a fault cross cutting the brittle upper crust and the ductile lower crust in the brittle layer the fault is assumed to have stick slip behaviour whereas the lower ductile crust is inferred to deform in a steady state shear therefore the brittle ductile transition bdt separates two layers with different strain rates and structural styles this contrasting behaviour determines a stress gradient at the bdt that is eventually dissipated during the earthquake during the interseismic period along a normal fault it should form a dilated hinge at and above the bdt conversely an over compressed volume should rather develop above a thrust plane at the bdt on a normal fault the earthquake is associated with the coseismic closure of the dilated fractures generated in the stretched hangingwall during the interseismic period in addition to the shear stress overcoming the friction of the fault the brittle fault moves when the weight of the hangingwall exceeds the strength of the dilated band above the bdt on a thrust fault the seismic event is instead associated with the sudden dilation of the previously over compressed volume in the hangingwall above the bdt a mechanism requiring much more energy because it acts against gravity in both cases the deeper the bdt the larger the involved volume and the bigger the related magnitude we tested two scenarios with two examples from l aquila 2009 italy and chi chi 1999 taiwan events gps data energy dissipation and strain rate analysis support these contrasting evolutions our model also predicts consistently with data that the interseismic strain rate is lower along the fault segment more prone to seismic activation

rupture directivity of the major shocks in the 1997 umbria marche central italy sequence from regional broadband waveforms we derive the relative moment rate function for the main shocks in the fall 1997 central italy seismic sequence mw 5 7 6 0 5 6 by applying an empirical green function method by using three conveniently placed broad band mednet stations we obtain clear source time functions indicating directivity effects for all of the three earthquakes with southeastward rupture propagation for the two southernmost events and an opposite direction for the other and largest one taking a simple source model forward modeling is utilized for determining fault parameters such as length rupture propagation velocity and direction and slip distribution

organic matter from the callovian middle jurassic deposits of lithuania compositions sources and depositional environments abstract this study presents the first organic geochemical and petrographical investigation of the callovian deposits of the eastern part of the central european basin it is shown that in both the terrigenous papil formation lower callovian and shallow to deeper marine facies of the papartin and skinija formations middle and upper callovian respectively terrestrial organic matter predominates this is reflected by the carbon preference index values higher than 1 2 for all samples and in some cases higher than 2 as well as the occurrence of characteristic higher plant biomarkers like cadalene dehydroabietane simonellite and retene moreover in the case of the papil formation sugiol a natural product terpenoid produced by distinct conifer families has been detected in clay sediments the occurrence of such a biomolecule in the middle jurassic clays is reported for the first time its occurrence is probably connected with the presence of small wood debris in the clay sediments in samples of the papil formation charcoal fragments co occurring with unsubstituted polycyclic aromatic hydrocarbons were detected indicating that wildfires took place during the early callovian of lithuania and or neighbouring areas in the middle and upper marine callovian sediments of lithuania there is no evidence of anoxic conditions occurring in the water column however periodic anoxic or strongly dysoxic episodes may have occurred most probably below the photic zone during the deepest phase of the late callovian transgression as is evidenced from pyrite framboid diameter distribution and general impoverishment of benthic fauna huminite reflectance r r values for the investigated area are in the range of 0 21 0 31 suggesting the occurrence of immature organic matter such values indicate that these investigated deposits were close to the surface during their whole diagenetic history and the thickness of younger cover did not exceed ca 500 m this is also supported by a biomarker analysis in which less thermally stable hopanes and hopenes significantly dominated

the 1997 umbria marche central italy earthquake sequence insights on the mainshock ruptures from near source strong motion records a small size foreshock and the two mainshocks of the umbria marche earthquake sequence which occurred on september 26 1997 have been recorded by two digital 3c accelerometers located at near source distances the close epicentral distance and azimuthal location relative to the fault orientation and geometry make these records relevant to look at the detail of the rupture kinematics s wave polarizations apparent source time duration and waveforms from strong motion records are used to constrain the location of the fracture origin point the fault geometry the final slip distribution size and mechanism of the events the final model shows that the seismic ruptures occurred along two adjacent sub parallel low angle dipping normal faults the relative timing location and geometry of the mainshock faults suggest the presence of a transfer zone barrier which has probably controlled the amplitude increase of local stress released by the first rupture at its nw edge which triggered about 9 hours later the second rupture

effects of weathering on organic matter i changes in molecular composition of extractable organic compounds caused by paleoweathering of a lower carboniferous tournaisian marine black shale abstract a detailed bulk and molecular study on paleoweathering of a lower carboniferous tournaisian black shale from the kowala quarry in the holy cross mountains of poland revealed significant changes in total organic carbon toc total sulfur ts and extract compositions paleoweathering resulted in a 97 decrease in toc and total loss of sulfur as well as changes in carbonate contents extract yields and percentage yields of the organic fractions pyrite framboids which are used extensively in paleoecological studies decreased considerably in the partially weathered zone and totally vanished in the weathered zone the decrease in toc is accompanied by a pronounced reduction of organic compound concentrations but the degradation range differs in the individual weathering zones here we show that less stable compounds such as low molecular weight aromatics e g methylnaphthalenes dibenzofuran and dibenzothiophene isorenieratane and its diagenetic products or maleimides decrease significantly or disappear already in the partially weathered zone while the more stable polycyclic aromatic hydrocarbons pahs decrease 90 only in the weathered and highly weathered zones besides the organic matter om content the influence of paleoweathering on the distributions of organic compounds is important in the context of paleoenvironment source and maturity interpretations almost all sterane and triterpane biomarker parameters change their values in the highly weathered zone but some ratios e g the 2 meh index are almost totally resistant to change the aryl isoprenoid ratio air values decrease gradually with weathering this modifies completely the potential interpretation of the nature of the photic zone anoxia in addition to degradation of om some pahs like benzo b fluoranthene increase in concentration in the partially weathered zone due to their formation from phenyl derivatives the correct recognition of paleoweathering in outcrop and drill core samples aids in the proper interpretation of biomarker parameters and contributes to a better understanding of the processes which took place during weathering

organic geochemical evidences of early diagenetic oxidation of the terrestrial organic matter during the triassic arid and semi arid climatic conditions abstract the molecular character of organic matter om present in triassic clays of the upper silesia basin and nw border of the holy cross mountains was determined using gc ms analysis oxidation processes were the major cause of the main changes of extractable om molecular composition during sedimentation and early diagenesis of the triassic clays they resulted in a very significant decrease in the om content of the clays and transformation of n alkanes triterpanes and steranes despite the changes in biomarker composition resulting from the disappearance of unsaturated and hopanes and dominance of and hopanes as well as preponderance of over steranes the aromatic ketones were identified such pacs as benzophenone fluorenone cyclopenta def phenanthrenone antracenone and benzanthrone were among the compounds identified in the red clays these commonly originate during oxidation of sedimentary organic matter moreover the aromatic fraction is characterized by the presence of phenyl derivatives phenylnaphthalenes terphenyls phenyldibenzofurans and phenylphenanthrenes that are also products of the abiotic oxidation of organic matter periods of terrestrial sedimentation have been interrupted by long phases of om weathering and oxidation during arid conditions and om might only have survived without significant oxidation changes when the sedimentation was fast and or long lasting

the interplay between global tectonic processes and the seismic cycle in the umbria marche seismogenic region summary for the central apennines peninsular italy a series of tectonic mechanisms are reproduced by means of finite element models in order to study the effects of active tectonics on the seismic cycle in the umbria marche seismogenic zone continental extension and rift push effects induced by small scale convection are modelled within 2 d viscoelastic models of the crust lithosphere system in vertical cross sections perpendicular to the strike of the major tectonic structures under study namely the apennines and the colfiorito fault zone where the 1997 seismic sequence took place with the aim of constraining the active tectonic mechanisms at the regional scale and the behaviour of the fault in the seismogenic zone at the local scale modelled baseline rate of change are compared with newly acquired gps data retrieved from the two permanent gps receivers of camerino came and elba elba deliberately installed along the modelled transect these receivers are located at both edges of the continental extension in the front of the apennines close to the adriatic plate in the east and in the rear of the chain in the tyrrhenian domain the deformation pattern inferred from seismicity and from the geodetic data is consistent with small scale convection in the tyrrhenian domain which reproduces extension in the rear of the apennines and compression in the front of the chain a convective mechanism associated with backarc opening and doming of the asthenosphere provides an extensional rate along a baseline connecting two sites in the front of the chain camerino and in its rear elba comparable to the observed baseline rate of change the viscosity of the lower crust plays a fundamental role in determining the style of stress in the crust lithosphere system once constrained by means of the extensional baseline rate inferred from gps the modelled slip across the colfiorito fault and the modelled earthquake recurrence time are consistent with the 1997 normal fault event and with palaeoseismicity respectively

edge diffracted 1 sec surface waves observed in a small size intramountain basin colfiorito central italy during the umbria marche central italy seismic sequence a small aperture 200 m four station array was operating in the colfiorito plain a few kilometers away from the epicenters of the ml 5 6 and 5 8 mainshocks of 26 september 1997 the array was deployed approximately 500 m from the eastern edge of the basin we analyze the three component seismograms of 12 aftershocks in a magnitude range of 2 5 to 4 1 amplitudes of the horizontal components are systematically higher than those of the vertical component with an average horizontal to vertical spectral ratio of about 3 at 1 hz in this frequency band earthquake induced ground shaking is highly coherent across the array a 1 sec running window zero lag cross correlation algorithm is used to compute apparent velocity and backazimuth of coherent wave trains in the frequency band 0 5 to 2 hz apparent velocity and backazimuth show a different behavior in the first part of the seismograms compared to the late coda the largest amplitude waves that is s waves and early coda are characterized by low apparent velocities mostly between 400 and 1200 m sec this suggests that near the rock edge the most significant part of seismic energy propagates horizontally in the basin backazimuth of these low frequency coherent wavetrains never coincides with the array to source direction the predominant backazimuth is peaked around n110 corresponding to the nearest steep outcrop of the basin edge the observed 1 sec coherent wave trains are interpreted as locally generated surface waves that are persistently diffracted from the nearby basin edge as long as a significant level of seismic radiation is incident to the bedrock when the bedrock excitation decreases a much larger variability of both apparent velocity and backazimuth is observed suggesting that in the coda randomly scattered waves within the basin and late arrivals of deeper origin become more important multipathing from the source to the site as well as multipathing within the basin are therefore interpreted as the main causes of the observed long duration coherent low frequency basin shaking

on the speed of the eddy driven jet and the width of the hadley cell in the southern hemisphere a strong correlation between the speed of the eddy driven jet and the width of the hadley cell is found to exist in the southern hemisphere both in reanalysis data and in twenty first century integrations from the intergovernmental panel on climate change ipcc fifth assessment report multimodel archive analysis of the space time spectra of eddy momentum flux reveals that variations in eddy driven jet speed are related to changes in the mean phase speed of midlatitude eddies an increase in eddy phase speeds induces a poleward shift of the critical latitudes and a poleward expansion of the region of subtropical wave breaking the associated changes in eddy momentum flux convergence are balanced by anomalous meridional winds consistent with a wider hadley cell at the same time faster eddies are also associated with a strengthened polewardeddymomentumflux sustainingastronger westerlyjet in midlatitudes the proposedmechanismis consistent with the seasonal dependence of the interannual variability of the hadley cell width and appears to explain at least part of the projected twenty first century trends one of the most salient features of earth s general circulation is the presence of hadley cells hcs in the tropical belts of both hemispheres associated with their large scale motions are some of the main characteristics of tropical and subtropical climates the intertropical convergence zone in the rising branch and the subtropical dry zones in the descending branches e g hartmann 1994 studying the factors determining the meridional extent of these overturning circulations is therefore essential to understand the spatial distribution of tropical and subtropical climates and its changes the role of the hcs is particularly crucial in the context of climate change and the observed widening of the atmospheric circulation observations show a poleward shift of the eddy driven jets and an expansion of the hcs in recent decades particularly in the southern hemisphere hu and fu 2007 johanson and fu 2009 lu et al 2009 and the role of radiative forcings induced by greenhouse gases and stratospheric ozone has been shown to be crucial in this context polvani et al 2011b

effects of weathering on biological marker and aromatic hydrocarbon composition of organic matter in phosphoria shale outcrop gc ms analyses were performed on core samples collected from a shale outcrop of the permian phosphoria formation in utah u s a to study effects of weathering on selected biological marker and aromatic phenanthrene hydrocarbon compounds among the biological markers the most important weathering effects are a decrease in 20s 20r diastereomer ratio of the c sub 29 steranes and loss of low molecular weight triaromatic steroids a decrease in the c sub 19 through c sub 22 tricylcic terpanes occurs relative to the total c sub 19 c sub 26 tricyclic fraction pronounced loss of methyl substituted phenanthrenes occurs relative to phenanthrene no major effect on the overall distribution of pentacyclic terpanes is evident

what causes weak orographic rain shadows insights from case studies in the cascades and idealized simulations abstractrecent studies have shown that weak rain shadows in the cascade mountains are associated with passing warm fronts but the specific mechanisms responsible for this connection have eluded consensus one theory holds that weak rain shadows are the result of enhanced precipitation over eastern slopes caused by easterly upslope flow the other suggests that condensation is produced primarily over the western slopes with enhanced east slope precipitation occurring in dynamical regimes that minimize descent and evaporation east of the crest here these mechanisms are investigated through numerical simulations involving both real and idealized topography consistent with the second theory storms with weak rain shadows are found to exhibit much weaker mountain waves in the lee of the cascades than storms with strong rain shadows with correspondingly weaker leeside evaporation the muted wave activity during weak rain shadow storms is found to be caused by cold zonally stagnant air at low levels in the

spatial structures in earthquakes and faults quantifying similarity in simulated stress fields and natural data sets abstract this paper presents an adaptation for fault analysis of the coherence method of kagan and knopoff kagan y y knopoff l 1985b the two point correlation function of the seismic moment tensor geophysical journal of the royal astronomical society 83 637 656 understanding coherence as a measure of the similarity between fault slip data for two faults which can be analytically computed from earthquake or fault moment tensors through the use of a customized gis routine the degree and distribution of similarity in synthetic and natural fault populations can be calculated as a function of distance between fault earthquake pairs and their relative orientation stress simulations using synthetic data sets reveal that fault populations which developed under homogeneous stress fields have a high degree of similarity that increases with the slip tendency of faults stress ratio variations and especially stress axis rotations lower the coherence values spatial analysis of natural earthquake and fault data sets from the umbria marche region northern apennines italy reveals a common pattern of coherence spatial cyclicities in faults earthquakes controlled by two consecutive tectonic phases miocene compression and plio pleistocene extension the proposed interpretation attributes the spatial cyclicities of miocene data to syn to post faulting folding in agreement with wavelengths derived from field data the observed periodicities in earthquakes 1997 colfiorito sellano umbria marche seismic sequence could in turn have been controlled by the miocene thrust structures with possible spatial stress field axis rotations and or stress ratio variations the spatial characteristics of younger fault earthquake populations are thus possibly controlled by the characteristics of older tectonic structures such as fold wavelength or fault spacing

mechanisms setting the strength of orographic rossby waves across a wide range of climates in a moist idealized gcm abstractorographic stationary rossby waves are an important influence on the large scale circulation of the atmosphere especially in northern hemisphere winter changes in stationary waves with gl

deriving wavefield characteristics and shear velocity profiles from two dimensional small aperture arrays analysis of ambient vibrations in a small size alluvial basin colfiorito italy we analyze the dispersion characteristics of ambient noise vibrations for this purpose two dimensional 2d seismic array data were acquired in four different sites in the colfiorito plain an alluvial intramountain basin that exhibits strong site effects assuming seismic noise being mainly composed of surface waves we derive one dimensional 1d shallow shear velocity profiles through the inversion of dispersion curves measured by frequency wavenumber f k methods the inverted shear wave velocity profiles are consistent with a priori information for those sites that can be approximated by 1d simple models in these cases the use of passive records of seismic vibrations can be a valuable tool for determining the shallow velocity profile if a detailed depiction of velocity structure is not required the theoretical dispersion curves for rayleigh and love waves were compared with the measured dispersion curves for vertical and horizontal components respectively this allows us to discuss qualitatively the composition of ambient vibrations outlining a large proportion of love waves in the noise wave field and the effects of higher modes we also use the single station method for investigating the origin of the horizontal to vertical h v peak in the plain of colfiorito in terms of ellipticity of the fundamental rayleigh mode

modelling of ground motion in the higashinada kobe area for an aftershock of the 1995 january 17 hyogo ken nanbu japan earthquake summary we model the ground motion from an aftershock of the 1995 january 17 hyogo ken nanbu kobe earthquake to investigate basin edge effects on wave propagation in higashinada ward downtown kobe point source finite difference seismograms calculated using a double couple solution and a 2 d basin structure are compared with the ground motion velocity seismograms recorded in a small station array deployed at sites within and outside the heavily damage zone in higashinada ward the comparison suggests that in the frequency range 0 1 2 hz that was analysed the observed spatial amplitude variation of the aftershock ground motion is attributable mainly to the basin edge effects we found that the basin edge effect caused by the superposition of the direct s wave and the basin edge diffracted waves amplified the ground motion in a narrow zone that is offset by about 0 7 km from the basin edge

age and origin of the well preserved organic matter in internal sediments from the silesian cracow lead zinc deposits southern poland the molecular and petrographic characteristics of organic matter in internal sediments from the mississippi valley type lead zinc deposits in southern poland reveal immature and well preserved organic matter huminite reflectance values of organic matter in all internal sediments are low with a mean value of 0 29 corresponding to a lignite range of coalification most organic compounds in the organic matter e g cadalene retene simonellite perylene and sitosterol and its transformation products stigmastanol and stigmasta 3 5 dien one as well as lignin degradation compound products e g benzoic acid vanillin 4 benzaldehyde benzenedicarboxilic acids and hydroxybenzoic acids are of terrestrial origin monosaccharides with dominant and glucose were identified as possible remnants of cellulose degradation products suggesting an excellent state of organic matter preservation given that monosaccharides are preserved only under conditions of limited oxygen after sedimentation resulting from the rapid accumulation of internal sediments in meteoric paleokarst cavities followed by insignificant diagenesis petrologic and palynological data on internal sediments clearly indicate a middle triassic age for organic matter and for the development of a triassic meteoric karst system immediately after anisian carbonate sedimentation

statistical analysis of triggered seismicity in the kresna region of sw bulgaria 1904 and the umbria marche region of central italy 1997 a version of the restricted trigger model is used to analyse the temporal behaviour of some aftershock sequences the conditional intensity function of the model is similar to that of the epidemic type aftershock sequence etas model with the restriction that only the aftershocks of magnitude bigger than or equal to some threshold mtr can trigger secondary events for this reason we have named the model restricted epidemic type aftershock sequence retas model varying the triggering threshold we examine the variants of the retas model which range from the modified omori formula mof to the etas model including such models as limit cases in this way we have a quite large set of models in which to seek the model that fits best an aftershock sequence bringing out the specific features of the seismotectonic region struck by the crisis we have applied the retas model to the analysis of two aftershock sequences the first is formed by the events which followed the strong earthquake of m 7 8 which occurred in kresna sw bulgaria in 1904 the second includes three main shocks and a large swarm of minor shocks following the quake of 26 september 1997 in the umbria marche region central italy the mof provides the best fit to the sequence in kresna that leads to the thought that just the stress field changes due to the very strong main shock generate the whole sequence on the contrary the complex behaviour of the seismic sequence in umbria marche appears when we make the threshold magnitude vary setting the cut off magnitude m0 2 9 the best fit is provided by the etas model while if we raise the threshold magnitude m0 3 6 and set mtr 5 0 the retas model turns out to be the best model in fact observing the time distribution of this reduced data set it appears more evident that especially the strong secondary events are followed by a cluster of aftershocks

geochemistry of quaternary travertines in the region north of rome italy structural hydrologic and paleoclimatic implications in the tyrrhenian region of central italy late quaternary fossil travertines are widespread along two major regional structures the tiber valley and the ancona anzio line the origin and transport of spring waters from which travertines precipitate are elucidated by chemical and isotopic studies of the travertines and associated thermal springs and gas vents there are consistent differences in the geochemical and isotopic signatures of thermal spring waters gas vents and present and fossil travertines between east and west of the tiber valley west of the tiber valley 13c of co2 discharged from gas vents and 13c of fossil travertines are higher than those to the east to the west the travertines have higher strontium contents and gases emitted from vents have higher 3he 4he ratios and lower n2 contents than to the east fossil travertines to the west have characteristics typical of thermogene thermal spring origin whereas those to the east have meteogene low temperature characteristics including abundant plant casts and organic impurities the regional geochemical differences in travertines and fluid compositions across the tiber valley are interpreted with a model of regional fluid flow the regional mesozoic limestone aquifer is recharged in the main axis of the apennine chain and the groundwater flows westward and is discharged at springs the travertine precipitating waters east of the tiber valley have shallower flow paths than those to the west because of the comparatively short fluid flow paths and low normal heat flow the groundwaters to the east of the tiber valley are cold and have co2 isotopic signatures indicating a significant biogenic contribution acquired from soils in the recharge area and limited deeply derived co2 in contrast spring waters west of the tiber valley have been conductively heated during transit in these high heat flow areas and have incorporated a comparatively large quantity of co2 derived from decarbonation of limestone the elevated strontium content of the thermal spring water west of the tiber valley is attributed to deep circulation and dissolution of a triassic evaporite unit that is stratigraphically beneath the mesozoic limestone u series age dates of fossil travertines indicate three main periods of travertine formation ka 220 240 120 140 and 60 70 based on the regional flow model correlating travertine deposition at thermal springs and precipitation in the recharge area we suggest that pluvial activity was enhanced during these periods our study suggests that travertines preserve a valuable record of paleofluid composition and paleoprecipitation and are thus useful for reconstructing paleohydrology and paleoclimate

connecting seismically active normal faults with quaternary geological structures in a complex extensional environment the colfiorito 1997 case history northern apennines italy 1 the northern apennines of italy are characterized by a complex tertiary tectonic history where superposed compressional and extensional deformation occurred in such regions characterized by low active extensional strain rate the coseismic surface ruptures are rare and often a matter of much debate resulting in a difficult connection between geological faults i e faults which can be mapped at the surface and seismological faults i e faults which actually generate earthquakes the availability of detailed geological mapping and high resolution seismological data for the colfiorito area struck in 1997 by a sequence of six 5 mw 6 normal faulting earthquakes allow us to compare and verify the existence of geometric and kinematic correspondence between the mapped geological quaternary faults and the activated structures in map view the earthquakes distribution reflects the fault pattern mapped at the surface the length of activated and mapped faults is quite similar 7 10 km the coseismic subsided region imaged by interferometric synthetic aperture radar data is located in the hanging wall of the mapped normal faults that bound the quaternary basins in section view there is a geometric connection between mapped normal faults and the aftershock alignments used to image fault geometry at depth comparison of striated fault planes and aftershock focal mechanism solutions show a strong kinematic consistency this study points out that the quaternary tectonosedimentary evolution and the present day geological and geomorphologic setting of the colfiorito area can be interpreted as the result of repeated extensional earthquakes similar to the 1997 events occurring on nw se trending normal faults our data also show that the main shocks of the colfiorito sequence nucleated close to the intersections between the normal faults and the preexisting compressional transpressional structures which in 1997 acted as lateral barriers to rupture propagation and consequently constrained the fault size

comparison between reprocessed seismic profiles seismologic and geologic data a case study of the colfiorito earthquake area seismic reflection data are used to reconstruct the subsurface geologic structures below the umbria marche region in italy a highly seismogenic area with a recent history of seismic activity the 1997 1998 colfiorito sequence we reprocess three vibroseis seismic profiles acquired in the early 1980s for hydrocarbon exploration whose stacked sections were optimized for relatively deep oil targets on the reprocessed seismic profile closest to the epicentral area we construct the main reflectors to a depth of about 4 s two way time and compare this interpretation with the available hypocenters of the 1997 earthquakes the improvements in visualizing the shallow and deep reflections provide a better correlation between the reflectors and the observed surface structures as well as a better delineation of the basement rock geometry we find that part of the colfiorito sequence is localized around some of the reflectors in the reflection profile which we interpret as related to the active normal faults

characterization of earthquake induced ground motion from the l aquila seismic sequence of 2009 italy summary based only on weak motion data we carried out a combined study on region specific source scaling and crustal attenuation in the central apennines italy our goal was to obtain a reappraisal of the existing predictive relationships for the ground motion and to test them against the strong motion data peak ground acceleration pga peak ground velocity pgv and spectral acceleration sa gathered during the mw 6 15 l aquila earthquake 2009 april 6 01 32 utc the l aquila main shock was not part of the predictive study and the validation test was an extrapolation to one magnitude unit above the largest earthquake of the calibration data set the regional attenuation was determined through a set of regressions on a data set of 12 777 high quality high gain waveforms with excellent s n ratios 4259 vertical and 8518 horizontal time histories seismograms were selected from the recordings of 170 foreshocks and aftershocks of the sequence the complete set of all earthquakes with ml 3 0 from 2008 october 1 to 2010 may 10 all waveforms were downloaded from the iside web page http iside rm ingv it iside standard index jsp a web site maintained by the istituto nazionale di geofisica e vulcanologia ingv weak motion data were used to obtain a moment tensor solution as well as a coda based moment rate source spectrum for each one of the 170 events of the l aquila sequence 2 8 mw 6 15 source spectra were used to verify the good agreement with the source scaling of the colfiorito seismic sequence of 1997 1998 recently described by malagnini et al 2008 finally results on source excitation and crustal attenuation were used to produce the absolute site terms for the 23 stations located within 80 km of the epicentral area the complete set of spectral corrections crustal attenuation and absolute site effects was used to implement a fast and accurate tool for the automatic computation of moment magnitudes in the central apennines

organic geochemical characteristics of black shales across the ordovician silurian boundary in the holy cross mountains central poland abstract black shales in the holy cross mountains area of poland provide a record of environmental change across the ordovician silurian boundary the changing depositional conditions have generated a variation in organic matter contents above and below the boundary investigating the organic constitution of these black shales has the potential to reveal how their organic matter contents were generated and how suitable these rocks and their lateral equivalents may be for exploitation as shale gas reservoirs one outcrop at the holy cross mountains with a continuous section across the ordovician silurian boundary occurs near the village of bardo stawy in the kielce region and contains sandy silty mudstones as well as grey and black shales organic geochemical analyses of samples at bardo stawy reveals low total organic carbon toc contents for ordovician samples and higher toc values for silurian samples organic biomarkers indicate that the ordovician rocks were deposited in a shallow marine shelf setting while the silurian rocks were deposited in a deeper marine environment the progressive increase in toc from the uppermost ordovician to the lowermost silurian rocks reflects increasingly oxygen poor depositional conditions during the post glacial transgression following the deposition and preservation of organic matter in the ordovician and silurian rocks these rocks were buried and subjected to thermal maturation rock eval and biomarker thermal maturity parameters all indicate that the organic matter is mature and lies within the oil window the ordovician and silurian shales have direct relevance to recent attempts to discover and exploit shale gas reservoirs in poland our data and interpretations suggest that the relatively low toc values

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

can the increase in the eddy length scale under global warming cause the poleward shift of the jet streams abstractthe question of whether an increase in the atmospheric eddy length scale may cause a poleward shift of the midlatitude jet streams is addressed an increase in the length scale of the eddy reduces its zonal phase speed and so causes eddies to dissipate farther from the jet core if the eddy dissipation region on the poleward flank of the jet overlaps with the eddy source latitudes shifting this dissipation to higher latitudes will alter which latitudes are a net source of baroclinic eddies and hence the eddy driven jet stream may shift poleward this behavior does not affect the equatorward flank of the jet in the same way because the dissipation region on the equatorward flank is well separated from the source latitudes an experiment with a barotropic model is presented in which an increase in the length scale of a midlatitude perturbation results in a poleward shift in the acceleration of the zonal flow initial investigations indicate that this behavior is also important in both observationa

effects of weathering on organic matter abstract bulk geochemical petrographical mineralogical and molecular compositions of unweathered weathered and transitional zones of a middle jurassic fossil wood were analyzed to trace changes caused by oxidative weathering of the immature terrestrial organic matter om the occurrence of such zones was confirmed by the mineral composition showing replacement of siderite and pyrite by goethite vitrinite reflectance analysis of weathered and unweathered fossil wood samples revealed that weathering elevated the vitrinite reflectance values by ca 0 1 which should be taken into account during modeling of low maturity terrestrial om in the weathered part of the wood most of the biomarkers and biomolecules were totally removed or the concentration decreased significantly the concentration of most of the polynuclear aromatic hydrocarbons pahs decreased by 50 80 being 90 for the more reactive and less stable benzo a pyrene and perylene on the other hand several aromatic compounds like phenanthrene and its methyl derivatives phenyl naphthalenes fluoranthene and oxygen containing aromatic compounds increased in concentration in the weathered zone this results from processes such as formation of phenyl derivatives of pahs and their cyclization as well as aromatization of diterpenoids and incorporation of oxygen into aromatic structures weathering should always be considered in studies of fossilized terrestrial om especially in the case of thermal maturation modeling because it significantly decreases the om content and total sulfur content changes vitrinite reflectance values and alters the extract composition as a result of organic compound degradation

interaction between shallow and subcrustal dislocations on a normal fault abstract we propose a model which may explain seismic sequences which are often observed in seismogenic regions as for example in the apenninic chain italy in particular we consider a normal fault and earthquakes taking place at different depths a first shock in a shallower layer and a second in a deeper one the normal fault is embedded in a viscoelastic half space as a consequence of the rheology there are two different brittle layers a shallower and a deeper one where earthquakes can nucleate between these two layers the rheological behavior is ductile the thicknesses of the layers depend on the geothermal profile that is calculated taking into account the profile of the thermal and rheological parameters with depth the fault plane crossing layers with different rheological behavior is heterogeneous in respect to the slip style seismic in the brittle layers aseismic in the ductile layer dislocations in the shallower layer are assumed to produce aseismic slip in the area of the fault belonging to the ductile layer the stress concentrated by the seismic and aseismic dislocations on the fault plane section in the deeper brittle layer is evaluated it is compared with the tectonic stress rate in order to calculate how much earlier the second earthquake would occur compared to if just the bare tectonic sstress was acting it results that such an advance is comparable with typical recurrence times of earthquakes and so a mechanism of interaction between different seismic sources mediated by aseismic slip can be supposed the strains and displacements at the earth s surface due to seismic and aseismic slip are calculated they are large enough to be detected by present geodetic techniques

unmasking the 1349 earthquake source southern italy paleoseismological and archaeoseismological indications from the aquae iuliae fault abstract the 9th september 1349 earthquake was one of the most catastrophic events experienced along the apennines at least three main shocks struck a vast area of the molise latium abruzzi regions and damage was even sustained by the distant monumental buildings of rome the southern most shock mw 6 7 occurred at the border between southern latium and western molise razing to the ground the towns of isernia venafro and cassino amongst others and devastating montecassino abbey as with other medieval catastrophic sequences e g in december 1456 mw 6 5 7 0 this earthquake has not yet been associated to any seismogenic source thus it still represents a thorn in the flesh of earthquake geologists we have here carried out a reappraisal of the effects of this earthquake and through an interpretation of aerial photographs and a field survey we have carried out paleoseismological analyses across a poorly known n130 normal fault that crosses the molise campania border this structure showed repeated surface ruptures during the late holocene the last one of which fits excellently with the 1349 event both in terms of the dating and the rupture dimension on the other hand archaeoseismic analyses have also indicated the faulting of an augustean aqueduct the amount of apparent offset of the aqueduct across the fault traces shows that there were other surface faulting event s during the roman high middle age period therefore in trying to ascertain whether these events were associated with known potentially of 346 ad or 848 ad or unknown earthquakes in the area it became possible that this 20 km long fault here named the aquae iuliae fault is characterized by high slip rates and a short recurrence time this is in agreement with both the similar behaviour of the neighbouring northern matese fault system and with recent gps analyses showing unexpectedly high extension rates in this area

three dimensional simulation of the near fault ground motion for the 1995 hyogo ken nanbu kobe japan earthquake abstract the 17 january 1995 hyogo ken nanbu earthquake is a typical example showing that the ground motions along basin edge faults can be very destructive in this study we simulate the near fault ground motion from this earthquake based on a kinematic fault model and a simplified 3d velocity structure of the kobe area the kinematic earthquake rupture and the wave propagation are modeled using a 3d finite difference method fdm our simulation identifies the basin edge effect as an important factor that influenced the ground motion amplification pattern in the kobe area we found that the coupling of the source directivity and basin edge effects causes impulsive ground motions with extremely high amplitude at periods greater than 1 sec and in a narrow zone offset less than 1 km from the basin edge the combination of these effects acted to create a fairly continuous band of amplification that extends about 30 km in an elongated zone parallel to the basin edge boundary in some areas localized site effects might have been as important as the abovementioned effects but they cannot explain the continuity of the extended east west zone of damage

the climatology of small scale orographic precipitation over the olympic mountains patterns and processes the climatology of small scale patterns of mountain precipitation is poorly constrained yet important for applications ranging from natural hazard assessment to understanding the geologic evolution of mountain ranges synthesizing four rainy seasons of high resolution precipitation observations and mesoscale model output from the penn state ncar mm5 reveals a persistent small scale pattern of precipitation over the 10 km wide 800 m high ridges and valleys of the western olympic mountains washington state usa this pattern is characterized by a 50 70 excess accumulation over the ridge crests relative to the adjacent valleys in the annual mean while the model shows excellent skill in simulating these patterns at seasonal time scales major errors exist for individual storms investigation of a range of storm events has revealed the following mechanism for the climatological pattern regions of enhanced condensation of cloud water are produced by ascent in stable flow over the windward slopes of major ridges synoptically generated precipitation grows by collection within these clouds leading to enhanced precipitation which is advected by the prevailing winds instances of atypical patterns of precipitation suggest that under certain conditions during periods with a low freezing level or convective cells fundamental changes in small scale patterns may occur however case studies and composite analysis suggest that departures from the pattern of ridge top enhancement are rare the basic patterns and processes appear robust to changes in temperature winds and background rainfall rates copyright 2008 royal meteorological society

a scheme for calculation of the liquid fraction in mixed phase stratiform clouds in large scale models a scheme for calculation of the liquid fraction f l in mixed phase stratiform clouds has been developed for use in large scale models an advantage of the scheme compared to the interpolation in temperature that is typically used is that it makes it possible to simulate the life cycles of mixed phase clouds and the differences between deep and shallow clouds the central part of the scheme is a physically based calculation of the growth of cloud ice crystals by vapor deposition at the expense of coexisting cloud liquid water the so called bergeron findeisen mechanism versions of this calculation have been derived for three different ice crystal habits spheres hexagonal plates or columns and for two different assumed spatial relationships of the coexisting cloud ice and liquid water horizontally adjacent or uniformly mixed the scheme also requires a parameterization of the ice crystal number concentration ni the variation with temperature of f l looks broadly realistic compared to aircraft observations taken in the vicinity of the british isles when the scheme is used in the csiro gcm if ni is parameterized using a supersaturation dependent expression due to meyers et al if fletcher s earlier temperature dependent expression for ni is used the scheme generates liquid fractions that are too large there is also considerable sensitivity to the ice crystal habit and some sensitivity to model horizontal resolution and to the assumed spatial relationship of the liquid water and ice a further test shows that the liquid fractions are lower in cloud layers that are seeded from above by falling ice than in layers that are not seeded in this way the scheme has also been tested in limited area model simulations of a frontal system over southeastern australia supercooled liquid water forms initially in the updraft but mature parts of the cloud are mostly glaciated down to the melting level this behavior which is considered to be realistic based on observations of similar cloud systems is not captured by a conventional temperature dependent parameterization of f l the variation with temperature of f l shows a marked sensitivity to the assumed spatial relationship of the liquid water and ice the results obtained using the uniformly mixed assumption are considered to be more realistic than those obtained using the horizontally adjacent assumption there is also much less sensitivity to the time step when the former assumption is used

upper crust tomographic structure of the central apennines italy from local earthquakes abstract we derived a three dimensional p and s waves velocity model of the first 9 km of crust in the central apennine from local earthquakes the data set used for the tomographic inversion was recorded from three component regional and local networks which operated in the region from 1979 to 1998 and consists of 984 earthquakes for these earthquakes we have at least eight phases a gap smaller than 200 and a total rms residual smaller than 0 6 s giving a total of 13190 p and 10257 s phases first arrivals the inversion is performed using the simulps12 code this technique iterates the estimated velocity model parameters defined at the nodes of a grid relocating the earthquakes with an approximate 3 d ray tracing a large positive p and s wave velocity anomaly is observed in correspondence to the main seismogenetic volume of the central apennines a synthetic test demonstrates that this anomaly is not artificially produced by the substantially higher density of earthquakes within the seismic velocity anomaly this anomaly corresponds to the carbonatic rocks that form the core of the fold and thrust central apennines belt these rocks are underlain by ductile evaporite formations which were justaposed during the tectonic evolution of the belt we suggest that the evaporite layers effectively decouple the upper crustal seismogenetic volume from the middle and lower crust we conclude that the accumulation of seismic energy could be induced by gravitational tectonic processes explaining the fact that most of the seismicity is confined above the evaporites

velocity and attenuation tomography of the umbria marche 1997 fault system evidence of a fluid governed seismic sequence abstract the 1997 umbria marche is probably the best ever monitored normal faulting seismic sequence seismicity migration and multiple main shocks characterize the activation of a 40 km long system of contiguous fault segments as documented by seismological data many authors as indicative of fault weakening by fluids migration have interpreted this behaviour in this study we create a new catalogue of high quality p and s wave arrival times merging data recorded by permanent and temporary stations to improve the resolution of velocity and attenuation models and earthquake locations we show that the relocated earthquakes and the joint interpretation of p and s wave velocity and attenuation models help in understanding the faulting processes revealing new details of the geometry of the main faults and physical state of fluids within the crustal volume we observe that large aftershocks occur on the top and within the triassic evaporitic layer a rock volume locally characterised by fluid over pressured as evidenced by high vp vs and low qp qs anomalies velocity and attenuation heterogeneities are evidence that the migration of fluid pressure along the fault system is the driving mechanism of the prolonged earthquake sequence

co2 degassing over seismic areas the role of mechanochemical production at the study case of central apennines field observations coupled with experimental results show that co2 can be produced by mechanical energy applied to carbonate rocks becoming an unexpected additional gas source besides that degassed from the mantle or produced by thermometamorphism the evidence that a large amount of carbon dioxide associated with radiogenic type helium r ra as low as 0 01 0 08 is released through continental areas denotes the absence of a contribution from the mantle or from mantle derived fluids data collected during the seismic crisis which struck the central apennines in 1997 98 have shown an enhanced co2 flux not associated with the presence of mantle or thermometamorphic derived fluids on the other hand new experimental results highlight the possibility of producing co2 by mechanical energy that acts on the calcite crystalline lattice while the co2 released over the geothermal areas e g larderello geothermal field is obviously derived by mantlederived activities this is not the case of the huge amount of co2 released over the seismically active areas where the presence mantle derived products is ruled out we propose that mechanical energy e g released during seismic events microseismicity or creeping processes is a possible additional energy source able to produce co2 and thus could explain the presence of co2 degassing over tectonic areas where the influence of the mantle is low