frequency dependent seismic attenuation in the eastern united states as observed from the 2011 central virginia earthquake and aftershock sequence abstract ground shaking due to earthquakes in the eastern united states eus is felt at significantly greater distances than in the western united states wus and for some earthquakes it has been shown to display a strong preferential direction shaking intensity variation can be due to propagation path effects source directivity and or site amplification in this paper we use s and lg waves recorded from the 2011 central virginia earthquake and aftershock sequence in the central virginia seismic zone to quantify attenuation as frequency dependent q f in support of observations based on shaking intensity we observe high q values in the eus relative to previous studies in the wus with especially efficient propagation along the structural trend of the appalachian mountains our analysis of q f quantifies the path effects of the northeast trending felt distribution previously inferred from the u s geological survey usgs did you feel it data historic intensity data and the asymmetrical distribution of rockfalls and landslides

attenuation of coda waves in new england abstract seismic wave attenuation was measured in new england from the time domain decay of coda wave amplitudes on narrow bandpass filtered seismograms of local earthquakes the frequency band of interest was 0 75 to 10 hz q c f was found to increase with frequency across this band but there was also a difference between the q c f values for short t t 100 sec lapse times of coda wave propagation for the short lapse time data corresponding to wave paths primarily in the upper crust q c f increases from 400 at 3 hz to 1300 at 10 hz for the large lapse time data corresponding to wave paths in the lower crust and upper mantle q c f was found to vary from 660 at 1 hz to 1500 at 10 hz if we interpret this dataset in terms of a model incorporating both scattering and anelastic attenuation we find that the mean free path of seismic waves over this frequency band is 80 km for short lapse times and 400 km for long lapse times if we assume that scattering is entirely responsible for the observed attenuation we find that the minimum mean free path for short lapse times is about 75 km over all frequencies whereas for long lapse times the minimum mean free path decreases from 400 km at 0 75 hz to 90 km at 10 hz

the acquisition of source path and site effects from microearthquake recordings using q tomography application to the united kingdom source site and propagation parameters are inverted from a u k database of weak motion events 2 0 m l 4 7 this results in the complete spectral parameterization of over 3200 velocimetric records of 273 events from the year 1992 to 2006 the s wave is extracted from the vertical records and is processed using a multitaper fourier transform we initially use a nonlinear least squares log space optimization to obtain estimates of the attenuation parameter for each spectrum the estimates of t are then used to geometrically constrain a depth dependent q model using a technique adapted from velocity tomography we then invert for the remaining frequency dependent parameters and a collective amplitude parameter from the velocity spectra while fixing the newly computed attenuation parameters based on raytracing through our q model the resultant amplitude parameters are then split into source moments apparent geometrical spreading and site correction factors we find a frequency independent depth dependent q structure a linear relationship proportional to 0 7 m l between moment magnitude m w and local magnitude m l is found in the range of 2 4 7 m l the majority of stress drops are found to range on the order of 0 1 10 mpa a multiple segment apparent geometrical spreading model is found to best describe the amplitude decay with distance accounting for factors such as geometrical spreading and scattering along with multiple phase interference in the analysis window site response functions are found to broadly correlate with regional geology mean amplification occurring in the cenozoic sedimentary rock sites to the southeast of england relative to the harder palaeozoic rock sites of wales and scotland we use a bootstrap analysis technique to analyze the dependence of our results on the data in order to estimate the variance of the results and check the robustness of different inversions synthetic spectra are also computed in order to obtain minimum variance and bias of model parameters associated with the method in applying a geometrical q constraint through the use of q tomography we find that the robustness of the results is significantly increased a thorough analysis of the trade offs involved in the inversion is performed using synthetic datasets we find strong trade offs between the parameters but we are able to show that this covariance is reduced when adopting the q tomography approach

on regional s the character of regional s wave trains is quite complex and consists of two major elements sn waves which principally travel in the upper mantle and lg waves guided in the earth s crust the effect of lateral heterogeneity is to modify the signals for these phases compared with the predictions for horizontally stratified models however complete synthetic seismogram calculations for simple stratified crustal models for a suite of distances out to 950 km including both sn and lg provide a range of insights into the nature of the s wave train in particular late picks of sn arrivals are likely to arise because the actual s onset has been missed in the p coda and a higher amplitude surface multiple phase with an extra crustal delay has been picked instead such a effect was first recognized by lapwood 1955 in a study of the iss readings for a sequence of japanese events recorded at regional distances but has usually not been taken into consideration in studies using regional networks lateral heterogeneity along the propagation path has the effect of inducing interconversion between sn and lg energy and thus alters the character of the s wave train the lower attenuation for s in the uppermost mantle compared with the crust frequently leaves sn as the most prominent phase at ranges greater than 1000 km long range propagation of high frequency lg requires a relatively undisturbed crust

an evaluation of seismic decoupling and underground nuclear test monitoring using high frequency seismic data an effective solution to the problem of the detection and identification of low yield coupled and fully decoupled underground nuclear explosions appears available via use of high frequency seismic data ranging up to 30 or 40 hz in order to evaluate detection identification capabilities when using such data it is necessary to estimate 1 spectral characteristics and relative amplitudes of both p and s waves from explosions and earthquakes over the frequency band from 5 to 40 hz 2 signal transmission characteristics over this band through pertinent types of earth structure and 3 recording system and ground noise characteristics over this frequency band in this study each of these topics is considered in turn as they relate to detection and discrimination of the signals from low yield coupled and decoupled explosions in the regional and teleseismic distance ranges estimates of the capabilities of specific hypothetical networks to detect and identify insofar as signal to noise ratio is an important factor in identification explosions within the ussr are then considered these estimates of signal detection capability provide the central focus for the study as they serve to translate diverse and rather complex sets of observational data and theory into concrete predictions of monitoring capability following the assessment of detection capabilities the problem of identification of small events is considered with particular emphasis on discrimination at regional distances where the network is calculated to provide signals of high signal to noise ratio the principal results and conclusions of this study are as follows 1 seismic system noise can be suppressed to levels well below ground noise at quiet sites up to frequencies at least as high as 30 40 hz when using presently available hardware 2 average amplitudes of high frequency noise in a variety of geological environments are very low and change little with time or season 3 transmission of high frequency p and s wave signals in the regional distance range in stable continental areas and shields is nearly as efficient as at 1 hz with effective q factors in shield areas being about 9000 and 4000 for high frequency pn and sn respectively while the effective q for pn waves in tectonic areas is about 1000 4 a properly designed and deployed network of 25 simple three component nonarray stations internal to the ussr and 15 similar stations surrounding the ussr is predicted to be capable of multistation detection at high signal to noise ratio of fully decoupled 1 kt explosions located at all potential decoupling sites within the ussr 5 by inference from the quantitative agreement of empirical observations and theoretical predictions when using lower frequency data over a great range of explosion yields we conclude that procedures based on the use of both detectable p and s waves will serve to identify explosion generated seismic signals at least as small as those expected from a fully decoupled 1 kt explosion

petrology geochemistry and u pb geochronology of magmatic rocks from the high sulfidation epithermal au cu chelopech deposit srednogorie zone bulgaria the chelopech deposit is one of the largest european gold deposits and is located 60 km east of sofia within the northern part of the panagyurishte mineral district it lies within the banat srednegorie metallogenic belt which extends from romania through serbia to bulgaria the magmatic rocks define a typical calc alkaline suite the magmatic rocks surrounding the chelopech deposit have been affected by propylitic quartz sericite and advanced argillic alteration but the igneous textures have been preserved alteration processes have resulted in leaching of na2o cao p2o5 and sr and enrichment in k2o and rb trace element variation diagrams are typical of subduction related volcanism with negative anomalies in high field strength elements hfse and light element lithophile elements hfse and rare earth elements were relatively immobile during the hydrothermal alteration related to ore formation based on immobile element classification diagrams the magmatic rocks are andesitic to dacitic in compositions single zircon grains from three different magmatic rocks spanning the time of the chelopech magmatism were dated by high precision u pb geochronology zircons of an altered andesitic body which has been thrust over the deposit yield a concordant 206pb 238u age of 92 21 0 21 ma this age is interpreted as the crystallization age and the maximum age for magmatism at chelopech zircon analyses of a dacitic dome like body which crops out to the north of the chelopech deposit give a mean 206pb 238u age of 91 95 0 28 ma zircons of the andesitic hypabyssal body hosting the high sulfidation mineralization and overprinted by hydrothermal alteration give a concordant 206pb 238u age of 91 45 0 15 ma this age is interpreted as the intrusion age of the andesite and as the maximum age of the chelopech epithermal high sulfidation deposit 176hf 177hf isotope ratios of zircons from the chelopech magmatic rocks together with published data on the chelopech area and the about 92 ma old elatsite porphyry cu deposit suggest two different magma sources in the chelopech elatsite magmatic area magmatic rocks associated with the elatsite porphyry cu deposit and the dacitic dome like body north of chelopech are characterized by zircons with hft90 values of 5 which suggest an important input of mantle derived magma some zircons display lower hft90 values as low as 6 and correlate with increasing 206pb 238u ages up to about 350 ma suggesting assimilation of basement rocks during magmatism in contrast zircon grains in andesitic rocks from chelopech are characterized by homogeneous 176hf 177hf isotope ratios with hft90 values of 1 and suggest a homogeneous mixed crust mantle magma source we conclude that the elatsite porphyry cu and the chelopech high sulfidation epithermal deposits were formed within a very short time span and could be partly contemporaneous however they are related to two distinct upper crustal magmatic reservoirs and they cannot be considered as a genetically paired porphyry cu and high sulfidation epithermal related to a single magmatic hydrothermal system centered on the same intrusion

a review of numerical experiments on seismic wave scattering this paper reviews applications of the finite difference and finite element methods to the study of seismic wave scattering in both simple and complex velocity models these numerical simulations have improved our understanding of seismic scattering in portions of the earth where there is significant lateral heterogeneity such as the crust the methods propagate complete seismic wavefields through highly complex media and include multiply scattered waves and converted phases e g p tosv sv top body wave to surface wave the numerical methods have been especially useful in cases of moderate and strong scattering in complex media where multiple scattering becomes important progress has been made with numerical methods in understanding how near surface low velocity basin structures scatter surface waves and vertically incident body waves the numerical methods have proven useful in evaluating scattering of surface waves and body waves from topography of both the free surface and interfaces buried at depth numerical studies have demonstrated the importance of conversions from body waves to surface waves andvice versa when lateral heterogeneities and topographic relief are present in the uppermost crust recently several investigations have applied numerical methods to study seismic wave propagation in velocity models which vary randomly in space this stochastic approach seeks to understand the effects of small scale complexity in the earth which cannot be resolved deterministically these experiments have quantified the relationships between the statistical properties of the random heterogeneity and the measurable properties of high frequency 1 hz seismograms these simulations have been applied to the study of many features observed in actual high frequency seismic waves including the amplitude and time decay of seismic coda the apparent attenuation from scattering the dispersion of waveforms and the travel time and waveform variations across arrays of receivers

s wave attenuation in the crust in northern greece abstract the attenuation of shear waves in the crust is estimated for frequencies between 1 5 and 12 0 hz by applying a single station method based on the rate of decay of the s wave to coda wave amplitude ratio with distance the data used come from local earthquakes that occurred in the thessaloniki area northern greece during the period 1983 through 1989 and were recorded by the telemetered network of the geophysical laboratory of the university of thessaloniki the q s values obtained are 115 244 477 and 755 for 1 5 3 0 6 0 and 12 0 hz respectively these values are very close to the coda q values estimated for the same area using the s to s single scattering model for lapse times between 30 and 100 sec but they are higher than the coda q values for lapse times between 10 and 30 sec the estimated q s is found to be strongly frequency dependent proportional to f 0 91 which is very close to the frequency dependence of the coda q

imaging p and s attenuation in the sacramento san joaquin delta region northern california we obtain 3d q p and q s models for the delta region of the sacramento and san joaquin rivers a large fluvial agricultural portion of the great valley located between the sierra nevada batholith and the san francisco bay coast ranges region of active faulting path attenuation t values have been obtained for p and s data from 124 distributed earthquakes with a longer variable window for s based on the energy integral we use frequency dependence with an exponent of 0 5 consistent with other studies and weakly favored by the t s data a regional initial model was obtained by solving for q as a function of seismic velocity in the final model the great valley basin has low q with very low q 50 for the shallowest portion of the delta there is an underlying strong q contrast to the ophiolite basement which is thickest with highest q under the sacramento basin and a change in structure is apparent across the suisun bay as a transition to thinner ophiolite moderately low q is found in the upper crust west of the delta region along the faults in the eastern north bay area whereas moderately high q is found south of the delta implying potentially stronger ground motion for earthquake sources to the south very low q values in the shallow crust along parts of the major fault zones may relate to sediment and abundant microfractures in the lower crust below the san andreas and calaveras hayward rodgers creek fault zones the observed low q is consistent with grain size reduction in ductile shear zones and is lowest under the san andreas which has large cumulative strain similarly moderately low q in the ductile lower crust of the bay area block between the major fault zones implies a broad distributed shear zone online material distribution of earthquake magnitude figures of t values 3d initial regional velocity and q models station terms and q p inversion with 1d initial q p model

attenuation seismic moments and site effects for weak motion events application to the pyrenees we derive attenuation models site response functions and source parameters from small magnitude events recorded at a regional scale our data set consists of 45 pyrenean events with magnitude 2 7 to 5 4 recorded at distances from 15 to 200 km for which about 600 displacement spectra could be computed we assume that the far field displacement spectrum is the product of source propagation and site effects s wave displacement spectra are computed for accelerometric and velocimetric records using fast fourier transforms by integration in the frequency domain for 0 5 15 hz owing to the velocimeter response the spectra may be unreliable below 1 hz a brune type source is assumed attenuation is decomposed into a frequency dependent term anelastic attenuation and a non frequency dependent term geometric attenuation adapting a process proposed by scherbaum and wyss 1990 we invert the data with a two step regression the first step recovers the geometric attenuation the seismic moment and a frequency independent scaling factor the second step gives the corner frequency the anelastic attenuation and a frequency dependent site effect our results show that the propagation term includes a slightly superspheric geometric attenuation that varies as 1 r 1 2 and an anelastic attenuation that cannot be safely resolved with a linear approach computed moment magnitudes are generally 0 5 to 1 unit smaller than local magnitudes corner frequencies decrease linearly with magnitude and the stress drops obtained appear to be nearly constant whatever the magnitude finally robust site responses are computed that are compatible with those derived with other methods

anisotropic radiation modelling of macroseismic intensities for estimation of the attenuation structure of the upper crust in greece a method is suggested for the analysis of macroseismic intensity data in order to accurately determine an average attenuation structure of the upper part of the crust in an area the method is based on a model which assumes that the observed intensities depend on source properties radiation pattern size focal depth geometrical spreading and anelastic attenuation the method is applied to 13 008 intensity values observed in corresponding sites of greece and grouped in 4228 groups according to their spatial clustering in order to diminish observational errors and site effects an average intensity attenuation coefficient c 0 0039 0 0016 corresponding to a quality factor q 350 140 is determined for the upper 20 km of the crust in this area this value is relatively low in good agreement with the relatively high heat flow and high seismic activity of this area a byproduct of the present study is the determination for each earthquake of a macroseismic focal depth and of a macroseismic size which is strongly correlatted with both the earthquake s magnitude and its seismic moment determined by independent methods

finite difference simulations of seismic scattering implications for the propagation of short period seismic waves in the crust and models of crustal heterogeneity synthetic seismograms produced by the finite difference method are used to study the scattering of elastic and acoustic waves in two dimensional media with random spatial variations in seismic velocity the results of this study provide important insights about the propagation of short period 5 the self similar medium is characterized by a scattering q that is constant with frequency whereas theory predicts that the apparent q in an exponential medium is proportional to frequency these alternative models of crustal heterogeneity can thus be tested by improved measurements of the frequency dependence of crustal q at frequencies greater than about 1 hz assuming that scattering is responsible for most of the attenuation at these frequencies measurements of the time decay of the synthetic coda waves clearly show that the single scattering model of coda decay is not appropriate in the presence of moderate amounts of scattering attenuation scattering q 200 in these cases q values derived from the coda decay rate using the single scattering theory do not correspond to the transmission q of the medium the cross correlation of synthetic waveforms observed for an array of receivers along the free surface is observed to be dependent on the correlation distance of the medium the self similar random medium proposed here for the crust produces waveform variations at high frequencies 15 30 hz similar to those reported for actual small scale seismic arrays with apertures of hundreds of meters

simulation of earthquake ground motions in the eastern united states using deterministic physics based and site based stochastic approaches abstract earthquake ground motion recordings are scarce in the central and eastern united states ceus for large magnitude events and at close distances we use two different simulation approaches a deterministic physics based method and a site based stochastic method to simulate ground motions over a wide range of magnitudes drawing on previous results for the modeling of recordings from the 2011 m w 5 8 mineral virginia earthquake and using the 2001 m w 7 6 bhuj india earthquake as a tectonic analog for a large magnitude ceus event we are able to calibrate the two simulation methods over this magnitude range both models show a good fit to the mineral and bhuj observations from 0 1 to 10 hz model parameters are then adjusted to obtain simulations for m w 6 5 7 0 and 7 6 events in the ceus our simulations are compared with the 2014 u s geological survey weighted combination of existing ground motion prediction equations in the ceus the physics based simulations show comparable response spectral amplitudes and a fairly similar attenuation with distance the site based stochastic simulations suggest a slightly faster attenuation of the response spectral amplitudes with distance for larger magnitude events and as a result slightly lower amplitudes at distances greater than 200 km both models are plausible alternatives and given the few available data points in the ceus can be used to represent the epistemic uncertainty in modeling of postulated ceus large magnitude events

the digital array at anza california processing and initial interpretation of source parameters seismicity along the san jacinto fault suggests that a 40 km long section near the town of anza may constitute a gap in the occurrence of ml 6 7 earthquakes the potential for a gap filling shock and the high rate of seismicity at the southern end of the gap five events of 4 0 ml 5 5 since 1970 provided the impetus for deploying a digital seismic array to collect high quality ground motion recordings of all events 2 ml 4 5 on scale recording for shocks with magnitudes above ml 4 can be obtained from an existing array of eight strong motion accelerographs the anza site also had the advantage of being in the southern california batholith which appears to be relatively homogeneous compared to the franciscan gablian contrast of the central san andreas we expected that the granitic rocks of the batholith would yield relatively accurate earthquake locations and efficiently propagate high frequencies the field instrumentation is specifically designed for broadband recording up to 70 hz and high dynamic range 96 db in the on site digitizer alone since both are necessary for determining the rupture history of earthquakes both local vhf and microwave digital telemetry transmit the data from the anza region to san diego for computer data logging in the first 30 months of the array s operation approximately 292 events have been recorded located and processed for source parameters most events occur in one of five clusters or in a diffuse zone near the buck ridge fault two of these clusters are located at right stepping en echelon offsets coyote creek san jacinto and san jacinto hot springs two others are directly below and about 8 km west of anza respectively the fifth cluster is just to the northeast of the hot springs fault although event depths are generally between 11 and 14 km at the southern end of the hot springs fault depths extend to 18 km these are some of the deepest strike slip earthquakes on the san andreas system we calculate source parameters such as the scalar moment and stress drop for the analysis of high frequency waves scaling relations and earthquake interaction the largest event recorded thus far had a moment of 4 4 1021 dyn cm m 3 8 and a stress drop of 55 bars both arms and brune stress drops increase with moment source radius increases only slowly with moment the maximum values of both the brune and arms stress drops increase with depth down to 10 km remain approximately constant to 14 km and may decrease below 14 km the data suggest that stress drops of a group of earthquakes can be related to the strength of the upper crust calculated from frictional and quasi plastic flow laws although individual events may not be related stress drops on the san jacinto fault are high compared to those on the central creeping section of the san andreas where stress drops are about 10 bars or less this observation is consistent with the relative rupture area of events of equal ml 5 5 and may be related to the lithologie differences between the two fault segments and the amount of normal stress compared to shear stress

crustal heterogeneity and subduction processes 3 d vp vp vs and q in the southern north island new zealand summary along the southern hikurangi subduction zone in the southern north island new zealand the subduction zone changes from volcanic with moderately weak interseismic coupling to non volcanic with strong coupling in wellington to investigate how material heterogeneity relates to subduction processes we compute 3 d seismic properties using 342 earthquakes and 2 shots recorded by a 165 station seismic array the time base for some telemetered temporary stations was not stable which required revising the inversion code to allow an additional origin time related to the telemetered stations progressive inversions from 2 d to fine 3 d were carried out for vp vp vs and qp combined interpretation of these three seismic properties highlights features of the subduction zone the subducted slab is imaged as a high velocity high q feature in the overlying crust from southeast to northwest there is low velocity in the accretionary wedge high velocity in the axial ranges and low velocity in the wanganui basin high vp vs and low qp characterize the crust east of the north island dextral fault belt high vp vs is imaged above the subducted slab to 40 km depth in the northern half of the study area low qp is also prominent above the slab particularly trenchwards of the volcanic region in marked contrast to the high vp vs the low qp above the slab extends as a continuous feature up to the low qp in the shallow crust underlying the volcanic region the low qp and high vp vs are correlated with the region of weaker coupling and are consistent with significant subducted sediments with associated fluid release vp vs is particularly sensitive to overpressured fluid in the compressional forearc whereas qp also images the hydrostatically pressured fluid transport in the more permeable extensional volcanic region the rheology of the lower crust of the overlying plate is a factor in large scale subduction coupling as evidenced by the terrane boundaries and haast schist in the section near wellington the changing rheology of the lower crust of the overlying plate in the southern north island also provides a possible explanation for the southward cessation of volcanism

comparison of seismic body wave and coda wave measures of q measurements of seismic attenuation q 1 can vary considerably when made from different parts of seismograms or using different techniques particularly at high frequencies these discrepancies may be methodological or may reflect earth processes to investigate this problem we compare body wave with coda q 1 results utilizing three common techniques i parametric fit to spectral decay ii coda normalization of s waves and iii coda amplitude decay with lapse time q 1 is measured from both body and coda waves beneath two mountain ranges and one platform from recordings made at seismic arrays in the caucasus and kopet dagh over paths 4 long if q is assumed frequency independent spectral decay fits show q s and q coda near 700 800 for both mountain paths and near 2100 2200 for platform paths similar values are determined with the coda normalization technique however frequency dependent parameterizations fit the data significantly better with q s 1 hz and q coda l hz near 200 300 for mountain paths and near 500 600 for platform paths lapse decay measurements are close to the frequency dependent values showing that both spectral and lapse decay methods can give similar results when q has comparable parameterizations above 6 hz coda measurements suggest some enrichment relative to body waves perhaps due to scattering but intrinsic absorption appears to dominate at lower frequencies all approaches show sharp path differences between the eurasian platform and adjacent mountains and all are capable of resolving spatial variations in q

high sr y magmas reflect arc maturity high magmatic water content and porphyry cu mo au potential examples from the tethyan arcs of central and eastern iran and western pakistan the temporal and geochemical evolution of arc magmatism that culminated in porphyry cu mo au deposit formation has been studied in three separate neo tethyan arc systems in central and eastern iran and western pakistan porphyry cu au deposits in the lut block of eastern iran formed in the middle eocene at the end of a period of extensive paleocene eocene volcanism porphyry cu mo deposits in the kerman belt of central iran formed in the middle miocene at the end of a period of voluminous eocene oligocene volcanism and porphyry cu au deposits in the chagai belt of western pakistan formed in four pulses during the eocene early miocene middle late miocene and late miocene pliocene after a prolonged period of arc magmatism that began in the late cretaceous and is still active in each region the late porphyry related magmas are more geochemically evolved and more hydrous as evidenced by the presence of hornblende phenocrysts than the preceding volcanic rocks we suggest that this reflects maturation of the arc magmatic system over a period of tens of millions of years leading to the generation of more evolved volatile rich magmas at later stages of the arc s history high magmatic water contents are a prerequisite for the shallow crustal emplacement of arc magmas and the subsequent generation of potentially ore forming subvolcanic magmatic hydrothermal systems it is thus suggested that the fertility of arc magmas within a given arc terrane can be assessed by observing the relative timing of plutonic suites later suites are more prospective noting the common presence of hornblende or biotite phenocrysts indicating high magmatic water contents and through lithogeochemical fingerprinting of magmatic fractionation processes relatively high sr y and la yb ratios and eun eu ratios 1 indicating abundant early hornblende fractionation and suppression of plagioclase crystallization in hydrous magmas

attenuation of seismic shear wave energy in switzerland summary modelling the attenuation of shear wave energy is an important component of seismic hazard analysis previous studies have shown how attenuation particularly in the uppermost layers of the crust is regionally dependent the impact of this is that the decay of energy radiating from an earthquake will vary from place to place to quantify the regional attenuation in switzerland we model the fourier spectral amplitude of small to moderate earthquakes recorded on the local seismic networks high frequency decay is parametrized by q and while apparent geometrical spreading models account for the frequency independent decay of energy we analyse ground motion encompassing the significant duration of shaking to provide models that are useful for the purpose of seismic hazard analysis two methods are used to estimate the whole path attenuation parameter t first a simultaneous fit of the source model and attenuation effects across the entire spectral bandwidth for earthquakes with m 2 and secondly a linear fit of an attenuation model to the high frequency part of the spectrum for earthquakes with m 3 5 the t parameter is found to vary with hypocentral distance consistent with a weakly attenuating crust and strongly attenuating uppermost layer 1 d tomographic inversions indicate a profile of increasing q with depth down to the moho frequency independent decay is parametrized using a three part model which allows for the inclusion of moho reflection phases in the spectrum in the range of 20 140 km in the swiss foreland and from 70 to 140 km in the swiss alps

the carpatho balkanides and adjacent area a sector of the tethyan eurasian metallogenic belt the tethyan eurasian metallogenic belt temb was formed during mesozoic and post mesozoic times in the area of the former tethyan ocean on the southern margin of eurasia with the afro arabian and indian plates to the south it extends from western mediterranean via the alps and southeastern europe through the lesser caucasus the hindu kush and the tibet plateau to burma and sw indonesia linking with the west pacific metallogenic belt the carpatho balkan region is one of the sectors of the temb characterized by some specific features the emplacement of ore deposits is related to a definite time interval and to specific tectonic settings such as

first thermochronological constraints on the cenozoic extension along the balkan fold thrust belt central stara planina mountains bulgaria the balkan fold thrust belt exposed in bulgaria and north east serbia is part of the north east vergent segment of the bi vergent eastern mediterranean alpine orogen it was formed during two distinct compressional stages the first one lasted from the middle jurassic to the early cretaceous and the second from late cretaceous to the paleogene although the compressional tectonic evolution of the balkan fold thrust belt since the middle jurassic and during most of the mesozoic is relatively well studied the final exhumation of the rocks of the belt during the cenozoic has remained poorly understood here we present the first thermochronological constraints based on fission track and u th sm he analysis showing that along the central part of the belt syn to post orogenic extension could have started as early as the middle eocene low temperature thermochronological analysis of samples collected from three areas reveals at least two phases of increased cooling and exhumation during the cenozoic the first exhumation phase took place between 44 and 30 ma and appears to be related to the syn to post orogenic collapse coeval with the earliest cenozoic extensional stage observed across the southern balkan peninsula a period of relative quiescence between 30 and 25 ma is followed by the next cooling stage between 25 and 20 ma which appears to be related to late oligocene to early miocene crustal extension across the balkan peninsula extension accommodated by the late miocene to recent age sub balkan graben system does not appear to have produced exhumation of rocks from beneath 2 4 km depth as it was not detected by the low temperature thermochronological methods applied in this study

influence of focal mechanism on peak accelerations of strong motions of the whittier narrows california earthquake and an aftershock focal mechanisms affect the pattern of the peak accelerations of the october 1 1987 whittier narrows earthquake and its october 4 aftershock the peak accelerations observed on 21 strong motion instrumentation program and 22 u s geological survey accelerograms correlate well with the ratio of shear wave amplitude computed from the thrust mechanism of the main shock and the strike slip mechanism of the aftershock this correlation means that seismic energy is radiated from the fault with close to the standard double couple radiation pattern at the frequencies 3 6 hz corresponding to the peak accelerations

spatial and temporal correlation between coda q 1 and seismicity and its physical mechanism from the analysis of local earthquake coda waves recorded by the benioff short period vertical seismograph at riverside california we found a surprisingly large and systematic temporal variation in coda q 1 in the southern california during the 55 year period from 1933 to 1987 comparison of the coda q 1 variation with the b value obtained for earthquakes with m 3 occurred in the area within 180 km from riverside corresponding to the area for which q 1 is estimated by the coda method led to an extraordinary result that coda q 1 correlates positively with b value with the correlation coefficient of 0 79 the significance of correlation cannot be rejected at the confidence level of 0 974 since the data used for measuring q 1 namely the coda part of seismograms and the data used for measuring b namely the seismicity catalog are totally independent the observed correlation supports strongly the physical reality of temporal change in both coda q 1 and b value the correlation between coda q 1 and b value has been reported for several other cases but the correlation was positive in some cases and negative in others our current preferred model for explaining the observed correlation is the following aseismic creep is going on from time to time over various sizes of cracks in the ductile part and in some cases in the brittle part of lithosphere at and near the plate boundary creep activities tend to increase the crack density and coda q 1 observed in the region if the creek occurs over distributed cracks with a certain predominant scale length spatial stress concentration may enhance seismicity for earthquakes with a similar size if this characteristic size is in the lower part of the magnitude range for which the b value is estimated the enhanced seismicity will increase b on the other hand if it is in the upper part of the magnitude range it will decrease b thus we can explain the observed strong correlation between coda q 1 and b value for both positive and negative cases the existence of such a characteristic crack size in a seismic region has been supported by various observations on earthquake scaling

three dimensional patterns of seismic deformation in the taiwan region with special implication from the 1999 chi chi earthquake sequence abstract we compile a comprehensive list of hypocentral locations and source parameters for earthquakes occurred in the taiwan region the collected database is used to construct 3d patterns of seismic deformation that are associated with various tectonic processes such as subduction and collision between the philippine sea plate and eurasia specifically we divide the entire taiwan region into a 3d grid of 10km interval and the amount of seismic moment released at each point is the sum of all individual events in the vicinity in case when the physical dimension of an earthquake is larger than 10km the corresponding seismic moment is distributed across multiple grid points this quantitative approach gives a better depiction on many first order features in the region the most intriguing one is that a significant deficit in the total amount of released seismic moment can be clearly identified around the chi chi source region before the big earthquake occurred in 1999 the deficit trough is then filled by the seismic moment of the chi chi earthquake sequence this deficit then fill pattern in a region s seismic moment distribution can be used as an indicator to pinpoint the locations of large earthquakes in the foreseeable future following this argument we suggest that disastrous earthquakes with magnitudes comparable to that of the chi chi earthquake are due for the two regions adjacent to the chi chi source area i e the miaoli hsinchu domain to the north and the chiayi domain to the south

body wave crustal attenuation characteristics in the garhwal himalaya india we estimate frequency dependent attenuation of p and s waves in garhwal himalaya using the extended coda normalization method for the central frequencies 1 5 2 3 4 6 8 10 12 and 16 hz with earthquake hypocentral distance ranging from 27 to 200 km forty well located local earthquake waveforms were used to study the seismic attenuation characteristics of the garhwal himalaya india as recorded by eight stations operated by wadia institute of himalayan geology dehradun india from 2007 to 2012 we find frequency dependent p and s wave quality factors as defined by the relations q p 56 8f 0 91 0 002 and q s 151 8f 0 84 0 002 by fitting a power law frequency dependence model for the estimated values over the whole region both the q p and q s values indicate strong attenuation in the crust of garhwal himalaya the ratio of q s q p 1 obtained for the entire analyzed frequency range suggests that the scattering loss is due to a random and high degree of heterogeneities in the earth medium playing an important role in seismic wave attenuation in the himalayan crust

studies of the seismic coda using an earthquake cluster as a deeply buried seismograph array loosely speaking the principle of green s function reciprocity means that the source and receiver positions in a seismic experiment can be exchanged without affecting the observed seismograms consequently the seismograms observed at a single observation location o and caused by a cluster of microearthquakes at locations ei are identical to the time series that would be measured by an array of stress meters emplaced at positions ei recording waves generated by a source acting at o by applying array analysis techniques like slant stacking and frequency wave number analysis to these seismograms we can determine the directions and velocities of the component waves as they travel in the earthquake focal region rather than at the surface we have developed a computationally rapid plane wave decomposition which we have applied to single station recordings of aftershocks of the 1984 morgan hill california earthquake the analysis is applied to data from three seismic stations having considerably different site geologies one is a relatively hard rock station situated on franciscan metamorphics one is within the calaveras fault zone and one is on semiconsolidated sand and gravels we define the early coda to be the part of the coda initiating immediately after the direct s wave and ending at twice the s wave lapse time the character of the s wave and early coda varies from being impulsive at the first station to highly reverberative at the last we examine waves in sequential time windows starting at the s wave and continuing through the early part of the coda at all seismic stations the early coda is dominated by a persistent signal that must be caused by multiple scattering probably within 2 km of each seismic station despite clear station to station differences in the character of the early coda coda q values measured in the late coda greater than twice the s lapse time agree well among stations implying that the mechanisms causing the varying behavior of the early coda do not control the coda decay rate at the stations we have considered coda q values measured on horizontal components of motion agree within a factor of 2 with those measured on vertical components we have not been able to determine the composition of the late coda because of a low signal to noise ratio our analysis technique however is quite appropriate for such a task

seismic wave attenuation in the greater cairo region egypt in the present study a digital waveform dataset of 216 local earthquakes recorded by the egyptian national seismic network ensn was used to estimate the attenuation of seismic wave energy in the greater cairo region the quality factor and the frequency dependence for coda waves and s waves were estimated and clarified the coda waves q c and s waves q d quality factor were estimated by applying the single scattering model and coda normalization method respectively to bandpass filtered seismograms of frequency bands centering at 1 5 3 6 12 18 and 24 hz lapse time dependence was also studied for the area with the coda waves analyzed through four lapse time windows 10 20 30 and 40 s the average quality factor as function of frequency is found to be q c 35 9f 0 9 0 02 and q d 10 2f 0 9 0 02 for coda and s waves respectively this behavior is usually correlated with the degree of tectonic complexity and the presence of heterogeneities at several scales the variation of q c with frequency and lapse time shows that the lithosphere becomes more homogeneous with depth in fact by using the coda normalization method we obtained low q d values as expected for a heterogeneous and active zone the intrinsic quality factor q i 1 was separated from the scattering quality factor q s 1 by applying the multiple lapse time domain window analysis mltwa method under the assumption of multiple isotropic scattering with uniform distribution of scatters the obtained results suggest that the contribution of the intrinsic attenuation q i 1 prevails on the scattering attenuation q s 1 at frequencies higher than 3 hz

40ar 39ar laserprobe direct dating of discrete deformational events a continuous record of early alpine tectonics in the pelagonian zone nw aegean area greece abstract the pelagonian zone of the hellenides which occurs in the northwestern aegean region of the eastern mediterranean contains remnants of a high pressure metamorphic belt which subsequently underwent localized reworking during low temperature deformational events formation of alpine deformational structures in the ossa massif northern pelagonian zone occurred at metamorphic temperatures which failed to reset most pre alpine 40ar 39ar cooling ages in muscovite porphyroclasts the low metamorphic temperatures at alpine times have preserved the argon isotopic signature in white mica bearing deformational structures which allows direct dating of these structures and refinement of the alpine tectonic history in the region after separation of carefully selected and characterized mica generations application of sensitive 40ar 39ar laserprobe dating has resulted in a continuous record of the early alpine tectonic history of the ossa massif from the early cretaceous well into the eocene the early alpine history of the ossa massif records cooling of basement thrust slices which are mostly hercynian granites and metamorphics below ca 350 c by 100 ma while lower tectonostratigraphic levels of the basement had already cooled below these temperatures at around ca 285 ma blueschist facies mylonite fabrics related to a top to ene direction of tectonic transport yield ages as old as 84 5 3 3 ma exhumation of the blueschist facies sequences was initiated at ca 54 ma and involved tectonic activity along blueschist facies and greenschist facies mylonites zones final wsw ward transport of the metamorphic sequence across the structurally lowest and supposed autochthonous series occurred at around 45 ma and resulted in termination of the ductile deformation history in the studied area this study confines the onset of high pressure metamorphism in the pelagonian zone to an interval between 100 ma and 85 ma and has shown that high pressure metamorphism had terminated by ca 54 ma the recognition of an early to middle alpine cycle lasting over 30 million years and involving crustal shortening high pressure metamorphism exhumation and subsequent crustal shortening is a key contribution to a better understanding of the early alpine tectonic history of the aegean region and eastern mediterranean

deep structures along the boundary of a collisional belt attenuation tomography of p and s waves in the greater caucasus summary seismic attenuation q 1 o fp and s waves shows a major discontinuity from the russian platform to the tectonically active greater caucasus broadband records show this boundary over paths 4 long as revealed by the decay of amplitude spectra from a digital seismic network flanking the greater caucasus we measure attenuation from individual spectra using a non linear least squares procedure to determine an attenuation parameter t simultaneously with source parameters at frequencies between 1 and 15 hz the t measurements are then inverted for spatial variations of q 1 with parametrizations of varying complexity model variance for heterogeneous structures improves by more than 30 per cent compared with homogeneous parametrizations site corrections also significantly improve the fit in these inversion results mountainous regions exhibit q values 2 3 times lower q s 775 75 than do the adjacent shields q s 2060 315 showing that the discontinuity is large for both regions q p is roughly equal to q s comparison of body wave to coda spectra indicates that intrinsic absorption rather than scattering dominates the q 1 measurements at least beneath the mountains hence q 1 variations may give a reasonable proxy for temperature if so then temperature beneath the mountains exceeds that beneath the shield by 70 400 c these temperature increases may not be high enough to generate widespread partial melting beneath the mountains but could produce regional metamorphism and could contribute substantially to isostatic compensation of the mountains whatever their origin the boundary in seismic attenuation is abrupt and large between stable craton and an adjacent mountain belt demonstrating that q 1 is a sensitive indicator of tectonic process

three dimensional attenuation structure of the hikurangi subduction zone in the central north island new zealand summary we use waveform data from 2708 earthquakes recorded by dense seismograph deployments in the central north island of new zealand to image the 3 d attenuation structure of the hikurangi subduction zone down to ca 300 km depth attenuation images are obtained by determining the quality factor of p waves qp using a t inversion with a previously determined 3 d seismic velocity model we have included limited frequency dependence for qp with qp being frequency independent above 10 hz and having a frequency dependence of f 10 0 5 below 10 hz the qp images provide further constraint on the large scale features associated with subduction and magmatism beneath the central north island and serve to refine interpretations of crust and upper mantle structure from vp and vp vs the subducted plate is the most prominent feature in the qp images its high qp 900 1200 is consistent with the ca 120 myr old slab being relatively cold qp is better at resolving the slab than vp the coincidence of a strong gradient in qp with the upper plane of the dipping seismic zone indicates that even below 75 km depth the upper envelope of seismicity provides a good estimate of the location of the plate interface the mantle wedge is generally imaged as a relatively low qp 400 feature below 50 km depth however there are significant changes evident in the wedge along the strike of the subduction zone the most pronounced low qp in the mantle wedge occurs from ca 50 to 85 km depth beneath the productive rhyolite dominated central segment of the taupo volcanic zone suggesting a close link between volcanism and low qp in the shallow mantle wedge there is a strong correlation between low qp l owvp and high vp vs in this part of the mantle wedge suggesting that high temperature is the controlling influence on qp there within 30 km of the surface of the slab there is a large change in qp but only a modest change in vp our results are consistent with a fluid rich viscous blanket being entrained with the motion of the subducted slab down to ca 140 km depth where hydrous melting of mantle peridotite initiates trenchward of the volcanic front a strong horizontal gradient to higher qp is imaged in the mantle wedge we interpret this as a stagnant mantle nose not involved in the corner flow of the adjacent mantle the distribution of qp within both the slab and the overlying plate provides support for dehydration embrittlement being important in promoting seismicity in the mantle of the slab where qp is high at shallow depth in the forearc it is usually underlain by low qp near the plate interface this suggests that competent terranes in the forearc may act as aquicludes increasing fluid content in the rocks below and hence might control the distribution of coupling at the plate interface

refined timing of porphyry copper formation in the serbian and bulgarian portions of the cretaceous carpatho balkan belt the bor district in serbia and the panagyurishte district in bulgaria are part of the mineralized late cretaceous carpatho balkan igneous belt 40 ar 39 ar laser probe radiometric age information from porphyry copper deposits of the two districts in this study provides new constraints on the timing of host rock emplacement and the hydrothermal alteration that is linked to the porphyry mineralization in the bor district igneous hornblende from the host intrusions has an average plateau age at 84 0 1 5 ma 2 the timing of alteration is constrained by white mica with an average inverse isochron age of 85 4 1 8 ma and an average plateau age at 86 6 1 0 ma elevated by a small excess 40 ar contribution together these analyses indicate that porphyry mineralization occurred around 85 ma in the panagyurishte district previous isotopic studies have produced much older host rock ages in the northwest than mineralization ages in the southeast ages of igneous and alteration mineral separates from elatsite and medet in the northwestern and central parts of the district from the present study confirm pluton emplacement at 90 8 0 8 ma but much younger alteration at 79 5 0 5 ma it is proposed that two episodes of magmatic hydrothermal activity have affected the district one at 91 ma with the emplacement of the majority of the plutonic rocks and one at 79 to 80 ma during which the alteration micas were reset integration of these new ages with existing radiometric age information emphasizes the complex history of magmatic hydrothermal activity along the immature late cretaceous carpatho balkan convergent margin

the anza array a high dynamic range broadband digitally radiotelemetered seismic array a small aperture seismic array has been deployed along a 30 km stretch of the san jacinto fault in the vicinity of the town of anza california the array was installed to study specifically the scaling laws of body wave spectra the character of high frequency ground motion the physical interpretation of seismic stress drops and the interaction of earthquakes this region was chosen for these studies due to its high rate of seismic activity in the 2 m 4 5 range the likelihood of a m 6 event in the next decade and the existence of the southern california batholith on either side of the fault reducing problems associated with attenuation and large scale anisotropy these studies employ an instrument package with a frequency response of 100 hz a dynamic range of 138 db a sampling rate of 250 times per second per component and a 16 bit a d converter the array consists of 10 three component stations telemetered via digital vhf radio to a nearby mountain peak and thence via a microwave link to la jolla california a minicomputer system monitors the array s performance detects events and records data upon demand initial results demonstrate the feasibility of digital transmission with an inherent increase in data quality over analog systems

3 geochronology and geodynamics of late cretaceous magmatism and cu au mineralization in the panagyurishte region of the apuseni banat timok srednogorie belt bulgaria abstract the apuseni banat timok srednogorie abts belt europe s most extensive belt of calc alkaline magmatism and cu au mineralization is related to the subduction of the tethys ocean beneath the european continental margin during the late cretaceous phase of the alpine himalayan orogeny economic deposits are restricted to certain segments along the belt and all major porphyry style and high sulphidation ore deposits in bulgaria are aligned on the panagyurishte corridor a narrow zone obliquely crossing the abts belt this paper reviews the geology geochemistry and geochronology of igneous and hydrothermal events along this corridor in a profile extending from the european continental basement in the north to the accretionary complex of the rhodopes in the south extensive u pb dating of zircons from subvolcanic intrusions and major plutons supplemented by published age data for magmatic rocks and hydrothermal ore deposits obtained by other methods reveals a general younging of magmatism from ca 92 ma in the north elatsite to ca 78 ma in the south capitan dimitrievo cu au deposits are restricted to the northern and central parts of the profile ranging in age from 92 to 86 ma while the southernmost part exposes more deeply eroded mid crustal plutons devoid of economic mineralization the age progression correlates with a north to south geochemical trend of decreasing crustal input into mantle derived magmas magmatism and ore formation in individual magmatic hydrothermal complexes along the profile is much shorter lived for example subvolcanic intrusions and porphyry cu au mineralization at the elatsite deposit and andesitic volcanism and high sulphidation au as cu mineralization at chelopech all occurred within a time span of about 1 million years the age progression of calc alkaline magmatism within the panagyurishte region bulgaria from north to south is explained as a consequence of slab retreat during oblique subduction this led to transtensional block faulting and subsidence and thus to the preservation of near surface magmatic hydrothermal products including economic cu au deposits accretion of continental fragments in the rhodopes south of the abts belt led to greater uplift of the youngest late cretaceous intrusions this removed any ore deposits that might have been formed in this area

new moment magnitude scale evidence of stress drop magnitude scaling and stochastic ground motion model for the french west indies in this study we analyse records from the les saintes seismic sequence following the mw 6 3 earthquake of 2004 november 11 which occurred close to guadeloupe french west indies 485 earthquakes with magnitudes from 2 to 6 recorded at distances between 5 and 150 km are used s waves fourier spectra are analysed to simultaneously determine source path and site terms the results show that the duration magnitude routinely estimated for the events that occurred in the region underestimate moment magnitude by 0 5 magnitude units over the whole magnitude range from the inverted seismic moments and corner frequencies we compute brune s stress drops we show that stress drops increase with increasing magnitude the same pattern is observed on apparent stresses i e the seismic energy to moment ratio however the rate of increase diminishes at high magnitudes which is consistent with a constant stress drop model for large events using the results of the inversions we perform ground motion simulations for the entire data set using the smsim stochastic simulation tool the results show that a good fit 0 25 with observed data is achieved when the source is properly described by its moment magnitude and stress drop and when site effects are taken into account although the magnitude dependent stress drop model is giving better results than the constant stress drop model the interevent variability remains high which could suggest that stress drop depends on other parameters such as the depth of the hypocentre in any case the overall variability is of the same order of magnitude as usually observed in empirical ground motion prediction equations

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

three dimensional attenuation model of the shallow hikurangi subduction zone in the raukumara peninsula new zealand 1 the material properties of the shallow subduction zone are imaged with data from a passive seismic deployment in the raukumara peninsula attenuation images are obtained using t values measured from 2848 spectra of p wave arrivals the t values are inverted for frequency independent three dimensional 3 d qp using a 3 d velocity model linked nodes in a preliminary 2 d inversion are used to obtain the most reliable initial model for 3 d inversions the results show the benefits of obtaining 3 d q in addition to 3 d vp and vp vs q is related to localized permeability and heterogeneity and thus 3 d q is an important tool for interpreting active tectonic regions qp in the shallow overlying plate generally corresponds to the mapped geology two high qp features 600 represent subducted seamounts or cretaceous volcanics within the overlying plate the gradient above the subducting plate is the strongest feature in the qp model with the slab having high qp 600 900 below 20 km depth and above the plate interface there is a zone of 50 decrease in qp and high vp vs about 10 km thick which represents actively subducting sediment and has distributed microearthquake activity associated with active underplating

northern california seismic attenuation 3d qp and qs models the geological complexity of northern california and its accreted terranes produces pronounced regional variations in the attenuation 1 q of earthquake waves using local earthquakes 3d q p and q s models have been obtained for this region that includes the san andreas fault system the great valley the sierra nevada batholith and the gorda subduction volcanic system path attenuation t values were determined from p and s spectra of 959 spatially distributed earthquakes magnitude 2 5 6 0 using 1254 stations from northern california earthquake data center networks and mendocino and sierra nevada temporary arrays the t data were used in q inversions using existing 3d velocity models and basic 10 km node spacing uneven data coverage was accommodated with linking nodes into larger areas for useful q images across the 3d volume results at shallow depth show very low q in the sacramento delta the eureka area and parts of the san francisco bay area in the brittle crust low q tends to be associated with regions of fault zones and microearthquakes in the ductile lower crust low q is observed below fault zones with large cumulative displacement and inferred grain size reduction with apparent broad ductile shear zones across the fault system in the coast ranges underlying active arc volcanoes low q features are apparent below 20 km depth under the long valley caldera two distinct partial melt features at 3 and 15 km depth are inferred moderately high q is associated with sierra nevada and salinian igneous rocks whereas the franciscan subduction complex shows moderately low q prominent high q relates to the great valley ophiolite the pattern of path specific attenuation rate from 3d q is generally similar to the pattern of psuedospectral acceleration residuals for the south napa earthquake indicating that it may be beneficial to incorporate 3d q models into future ground motion prediction equations for northern california online material figures of q p and q s resolution and station delays for t and table of q p v p q s and v s

silicate replacive high sulfidation massive sulfide orebodies in a porphyry cu au system bor serbia the cu au deposit of bor serbia represents a continuum of mineralization styles from porphyry style ore occurring in quartz magnetite chalcopyrite veins and chalcopyrite disseminations to high sulfidation epithermal cu au ores in pyrite chalcopyrite and anhydrite sulfide veins decisive for the great economic importance of bor is the presence of exceptionally rich high sulfidation massive sulfide orebodies composed of pyrite covellite chalcocite digenite and minor anhydrite and enargite they form irregular bodies measuring 0 5 10 million tons of ore grading up to 7 cu hosted by andesites and surrounded by intense argillic alteration this study focuses on a small but rich underground orebody mined out recently where limited drillcore is preserved for quantitative geochemical study this paper documents the vein relationships within the deep porphyry style orebody of borska reka the transitional porphyry epithermal veins and the overlying and laterally surrounding epithermal massive sulfides of the bor deposit geological observations indicate that the formation of massive sulfide orebodies concludes the ore formation mass balance calculations recast into geologically realistic bulk fluid rock reactions confirm textural evidence that near isovolumetric replacement of andesite host rocks is the dominant formation mechanism of massive sulfide orebodies at bor whereby all lithophile elements including si are dissolved and only ti stays relatively immobile while net volume changes for individual mineralization styles within the massive sulfide orebody vary from 16 volume loss to 127 volume gain overall volume change for the whole massive sulfide orebody was probably slightly negative brecciation is important only as means of creating channelways for reactive fluid that turns the andesite protolith into massive sulfide whereas net breccia infill occurred only locally

alunite 40ar 39ar and zircon u pb constraints on the magmatic hydrothermal history of the zijinshan high sulfidation epithermal cu au deposit and the adjacent luoboling porphyry cu mo deposit south china implications for their genetic association

separation of intrinsic and scattering q for volcanic areas a comparison between etna and campi flegrei abstract we studied the seismic attenuation in the short period range 1 24 hz at the campi flegrei volcanic area using the method of frankel 1991 to separate intrinsic and scattering attenuation parameters the results compared to those obtained at etna volcano show that scattering phenomena play a main role in the attenuation mechanism of the seismic waves for these two volcanic areas the comparison of the present results with those obtained in non volcanic areas allow us to re consider the importance of the molten materials magma as a main cause of the seismic attenuation in the active volcanic areas

coda q in two layer random media summary using the indirect boundary integral scheme for multiple scattering of seismic waves developed by benites aki yomogida 1992 we compute sh wave seismograms and measure frequency dependent characters of coda q in 2 d random media with a flat layer over a half space many circular cavities are randomly distributed in both the upper layer and the half space down to a certain depth called the lower layer simulating the upper and lower crusts the scattering strength and the intrinsic attenuation qi are varied for each layer and the s wave velocity is prescribed to be constant throughout the medium so that the computation of green s functions for the boundary integral is simple considering two basic parameters of our random media scattering strength and intrinsic attenuation qi we represent the shallow earth structure by an upper crust with large intrinsic attenuation and a lower crust with effective scatterers computations of coda q for several values of those parameters show that when the scattering is relatively strong coda q is roughly independent of frequency this result differs from the case of a uniformly random model where coda q peaks around kd 2 where k is the wavenumber and d is the cavity diameter if the scattering strength in the lower layer is large enough for multiple scattering to dominate over single scattering coda q strongly depends on the intrinsic attenuation in the lower layer q and these two values coda q l and q become similar we explain this feature as follows waves scattered in the upper layer attenuate quickly due to high intrinsic attenuation and contribute little to the coda envelope in a time window starting at twice the traveltime of the direct wave multiply scattered waves in the lower layer eventually arrive at the surface dominating the coda envelope which decays at a rate determined by the intrinsic attenuation in the lower layer q the hypothesis that the temporal decay of coda is controlled not by the scattering but by the energy leakage into a transparent underlying mantle is ruled out in general by our numerical simulations except at low frequencies although our model may be too simple to simulate the details of observed coda q coda q is likely to reflect the intrinsic attenuation in the earth s lower crust

attenuation of high frequency shear waves in the crust measurements from new york state south africa and southern california we compare the attenuation of high frequency 3 30 hz shear waves for crustal paths in new york state south africa and southern california over source receiver distances of about 10 400 km the data consist of digital recordings of s waves 5 100 km and lg waves 100 400 km produced by earthquakes we use a coda normalization method to remove the effects of site amplification and source excitation from the amplitudes of the s and lg waves over the entire distance range studied 10 400 km the amplitude decay of 3 hz shear wave energy is considerably less for the tectonicaily stable areas of new york and south africa than for the tectonicaily active region of southern california high frequency 30 hz s wave attenuation is significantly less for new york and south africa than for southern california for distances between 15 and 90 km we parameterize the decay with distance r of coda normalized shear wave amplitudes with a frequency independent q and geometrical spreading exponent where geometrical spreading is proportional to r for new york state the s wave amplitude decay 3 30 hz is well described by a frequency independent q of 2100 330 490 and of 1 3 0 1 the decay of lg wave amplitudes from 3 to 15 hz in the new york state region is fit with a frequency independent q of 1600 280 330 of 0 70 0 2 the s wave amplitudes 3 30hz in south africa yield a q of 1500 190 380 and of 1 3 0 1 fixing the geometrical spreading at r 0 5 produces an lg wave q estimate at 3 hz in south africa of 360 50 80 this lg wave q is low considering that south africa is a cratonic tectonicaily stable area the s wave amplitudes from southern california are described with a frequency independent q of 800 150 240 and a large geometrical spreading exponent of of 1 9 0 2 we find an lg wave q at 3 hz of 260 30 for southern california after constraining the geometrical spreading at r 0 5

anomalous seismic amplitudes measured in the los angeles basin interpreted as a basin edge diffraction catastrophe the los angeles basin passive seismic experiment labpse involved the installation of an array of 18 seismic stations along a line crossing the los angeles basin from the foothills of the san gabriel mountains through the puente hills to the coast at 3 5 km spacing between stations the array has much higher resolution than the permanent network of stations in southern california this resolution was found to be important for analyzing the factors that govern the amplitude variation across the basin we inverted spectra of p and s body wave seismograms from local earthquakes ml 2 1 4 8 for site effects attenuation and corner frequency factor using a standard model that assumes geometric spreading varying as inverse distance exponential attenuation and an x 2 source model the s wave attenuation was sep arable into basin and bedrock contributions in addition to the body wave analysis s wave coda were analyzed for coda q and coda determined site effects we find s wave q qs in bedrock is higher than in the basin high frequency qs is higher than low frequency qs coda q qc is higher than qs p wave q qp was not separable into basement and bedrock values so we determined an average value only the corner frequencies for p and s waves were found to be nearly the same the standard model fit over 97 of the s wave data but data from six clustered events incident along the basin edge within a restricted range of incidence and azimuth angles gen erated anomalous amplitudes of up to a factor of 5 higher than predicted we test whether such basin edge focusing might be modeled by catastrophe theory after ruling out site attenuation and radiation effects we conclude a caustic modeled as a diffraction catastrophe could explain both the frequency and spatial dependence of the anomalous variation

energy flux model of seismic coda separation of scattering and intrinsic attenuation a new model of seismic coda is presented based on the balance between the energy scattered from the direct wave and the energy in the seismic coda this energy flux model results in a simple formula for the amplitude and time decay of the seismic coda that explicitly differentiates between the scattering and intrinsic anelastic attenuation of the medium this formula is valid for both weak and strong scattering and implicitly includes multiple scattering the model is tested using synthetic seismograms produced in finite difference simulations of wave propagation through media with random spatial variations in seismic velocity some of the simulations also included intrinsic dissipation the energy flux model explains the coda decay and amplitude observed in the synthetics for random media with a wide range of scattering q in contrast the single scattering model commonly used in the analysis of microearthquake coda does not account for the gradual coda decay observed in the simulations for media with moderate or strong scattering attenuation scattering q less than or equal to 150 the simulations demonstrate that large differences in scattering attenuation cause only small changes in the coda decay rate as predicted by the energy flux model the coda decay rate is sensitive however more to the intrinsic q of the medium the ratio of the coda amplitude to the energy in the direct arrival is a measure of the scattering attenuation thus analysis of the decay rate and amplitude of the coda can in principle produce separate estimates for the scattering and intrinsic q values of the crust we analyze the coda from two earthquakes near anza california intrinsic q values determined from these seismograms using the energy flux model are comparable to coda q values found from the single scattering theory the results demonstrate that coda q values are at best measures of the intrinsic attenuation of the lithosphere and are unrelated to the scatteing q less

a scattering model to explain seismic q observations in the lithosphere between 1 and 30 hz observations of lithospheric q for shear waves in the range 1 30 hz reported in the literature are examined using a scattering model consisting of randomly distributed spheres for the single scattering approximation i have assumed 1 q 1 q sub i gv omega where q sub i is the intrinsic q due to anelasticity v is the velocity of shear waves omega is angular frequency and g is the turbidity g is taken as a constant in this paper since g integral n a sigmada where n a da is the number of scattering spheres of radius a unit volume and sigma is the scattering cross section for a sphere this suggests that geometrical scattering dominates this will be true for ka 1 where k is wavenumber based on this criterion and the observation that q is large i e g small at a frequency of 0 05 hz a is of the order of magnitude 1 10 km fits of observations of shear wave q from japan and central asia indicate that q sub i 2000 500 for the lithosphere of both regions g 0 01 km for the japan observations and g 0 005 km sup 1 for central asia

tectonic configuration of the apuseni banat timok srednogorie belt balkans south carpathians constrained by high precision r e o s molybdenite ages the apuseni banat timok srednogorie magmatic metallogenic belt abts belt forms a substantial metallogenic province in the balkan south carpathian system in southeastern europe the belt hosts porphyry skarn and epithermal deposits mined since pre roman times generally the deposits prospects and occurrences within the belt are linked to magmatic centers of calc alkaline affinity fifty one rhenium osmium re os ages and re concentration data for molybdenites define systematic geochronologic trends and constrain the geochemical metallogenic evolution of the belt in space and time from these data and additional existing geologic geochemical data a general tectonic history for the belt is proposed mineralization ages in apuseni banat timok and panagyurishte the central district of the larger e w srednogorie zone range from 72 83 81 88 and 87 92 ma respectively and clearly document increasing age from the northwestern districts to the southeastern districts further re os ages suggest rapidly migrating pulses of late cretaceous magmatic hydrothermal activity with construction of deposits in 1 m y districts in 10 m y and the entire 1 500 km belt in 20 m y ages in both timok and panagyurishte show systematic younging while deposit ages in banat and apuseni are less systematic reflecting a restricted evolution of the tectonic system systematic differences are also observed for molybdenite re concentrations on the belt scale re concentrations generally range from hundreds to thousands of parts per million typical of subduction related cu au mo pge porphyry systems associated with the generation of juvenile crust the geochronologic and geochemical trends are compatible with proposed steepening of subducting oceanic slab and relaxation of upper continental plate compression resulting influx of sub continental mantle lithosphere scml and asthenosphere provide a fertile metal source and heat while the subducting slab contributes connate and mineral dehydration fluids which facilitate partial melting and metal leaching of scml and asthenosphere cu au mo pge porphyry deposits may develop where melts are trapped at shallow crustal levels often with associated volcanism and epithermal style deposits south banat timok and panagyurishte mo fe pb zn skarn deposits may develop where felsic melts are trapped adjacent to mesozoic limestones at moderate crustal levels north banat and apuseni systematic spatial variations in deposit style commodity enrichment re os ages and re concentrations support specific tectonic processes that led to ore formation in a post collisional setting subduction of vardar oceanic crust may have stalled causing slab steepening and rollback the slab rollback relaxes compression facilitating and enhancing orogenic collapse of previously thickened balkan south carpathian crust the progression of coupled rollback orogenic collapse is evidenced by the width of late cretaceous extensional basins and northward younging of re os ages from panagyurishte 60 km 92 87 ma to timok 20 km 88 81 ma to apuseni banat 5 km 83 72 ma generation of a well endowed mineral belt such as the abts requires a temporally and spatially restricted window of magmatic hydrothermal activity this window is quickly opened as upper plate compression relaxes thereby inducing melt generation and ingress of melt to higher crustal levels the window is just as quickly closed as upper plate compression is reinstated the transient tectonic state responsible for economic mineralization in the abts belt may be a paleo analogue to transient intervals in the present subduction tectonics of se asia where much mineral wealth has been created in the last few million years

magmatism and metallogeny of the ridanj krepoljin belt eastern serbia and their correlation with northern and eastern analogues in the southwestern carpathians of sw romania and e serbia calc alkaline upper cretaceous paleogene subduction related magmatic rocks occur in two main zones the ridanj krepoljin belt e serbia represents the southern part of the western zone in this belt early maastrichtian dacites and subordinate andesites occur but there are indications of an unexposed granodioritic magmatism about 60 ma old pb zn ag and only subordinate cu mineralization is associated with this igneous activity the timok magmatic complex e serbia composed of upper cretaceous paleocene andesites and analogue intrusives represents the eastern zone south of the danube associated with this magmatism are cu au and very subordinate zn pb mineralization to the north sw romania in both zones mainly intrusive bodies diorites quartz diorites granodiorites monzonites of campanian paleocene age are exposed porphyry copper mo and in north pb zn cu mineralization are related to those intrusives the petrological and geochemical features of all these calc alkaline rocks are very similar it appears however that the associated polymetallic and the copper mineralization are both spatially and vertically separated

determination of lg wave attenuation using single station seismograms a case study for zimbabwe summary in this paper we show how the quality factor q may be calculated using a single seismograph station and a number of events recorded on analogue seismograms we followed nuttli s 1973 method and extended it to one seismograph station using the single station bulawayo bul we determined a mean q value of 650 for zimbabwe furthermore we considered different propagation paths over zimbabwe as the seismic waves travelled to bul and found a low q value of 350 for the deka fault zone the q value of 650 obtained in this study agrees well within error with that of 603 reported by chow et al 1980 using the multistation multi event method and lies within the range of q values 454 759 reported by xie mitchell 1990 using a back project method to image large scale lateral variations of lg coda q the results obtained are important as the q value constitutes part of the input data in seismic hazard calculations the method may be used to determine q in regions where there may be only one station with reliable analogue seismogram data

frequency dependent seismic attenuation within the hispaniola island region of the caribbean sea wedetermine frequency dependentattenuation1 qffor thehispanio la region using direct s and lg waves over five distinct passbands from 0 5 to 16 hz data consist of 832 high quality vertical and horizontal component waveforms recordedonshort period andbroadbandseismometersfromthedevastating12january 2010 m 7 0 haiti earthquake and the rich sequence of aftershocks for the distance range 250 700 km we estimate an average frequency dependent qf 224 27 f 0 64 0 073 using horizontal components of motion and note that qf estimated with lg at regional distances is very consistent across vertical and horizontal components we also determine a qf 142 21 f 0 71 0 11 for direct s waves at local distances 100 km the strong attenuation observed on both vertical and horizontal components of motion is consistent with expectations for a tectonically active region online material figures of filtered and broadband data lg and s wave ampli tudes and apparent frequency dependent q and tables of earthquake and station parameters

a comparison of earthquake coda waves at surface versus subsurface seismometers the coda waves of 21 parkfield earthquakes were recorded simultaneously at the surface and at a depth of 198 m we characterize these codas by computing 1 the time dependence of the integral of squared particle velocity 2 their frequency content 3 time frequency coda decay planes 4 the frequency dependence of root mean square ellipticity and 5 the difference in their normalized decay rates these five measures reveal significant differences in the early portion of the uphole versus downhole codas our analysis solves for coda q as an explicit function of both time and frequency average apparent coda q for the 21 events observed both at the surface and downhole is qa f 39 f f0 0 43 0 0 37 with the reference frequency and time defined at 1 hz and 1 s respectively coda q exhibits a trend in its value over the 1 month period of the study the trend correlates with a spatial variation in source locations and is not produced by temporal variations of the q of the medium the spectral ratio between the uphole signal and the downhole signal varies with time through the coda the early portion of the uphole coda experiences a pulse of low frequency energy not seen in the downhole coda to explain this observation we propose a model of the coda that includes body wave to surface wave scattering near the site in this model the near surface acts as both a filter and a scattering waveguide the coda at the surface is the sum of a coda produced by scattering deep in the lithosphere and a coda produced by scattering in the near surface the scattering in the near surface is made up of near vertically traveling multiples and horizontally travelling surface waves the guided waves are recorded in the surface coda but are absent from the coda recorded at depth the time frequency structure of the surface waves in the uphole coda is determined by the velocity scattering and attenuation characteristics of the site by fitting the model to our data we have found that the fractional conversion factor of body waves to surface waves travelling toward the receiver is 0 03 at the vineyard canyon site the relatively rapid damping of these trapped waves can be modelled by assuming a quality factor of qt 50 the principles of this model are general enough to be of use at other locations

regionalization of crustal coda q in the continental united states a contour map of crustal q sub 0 values for the entire united states is presented based on a scattering model to explain the coda waves of local and near regional earthquakes these coda q sub 0 values are in good agreement with q of lg waves data are obtained from over 250 local earthquakes with most magnitudes between 3 0 and 5 0 recorded by 25 wwssn and 27 lrsm stations throughout the continental united states these two sets of data provide a range of frequencies from 0 5 to 3 5 hz a frequency dependence of q is observed in the range of frequencies considered a power law dependence of the form q q sub 0 f f sub 0 sup eta is assumed the value of frequency dependence eta is found to be maximum in the tectonically active western united states and least in the stable regions of the central and south central united states the lowest q sub 0 values are obtained in the western united states with values ranging from 140 to 200 in the coastal plains average crustal q sub 0 values for the basin and range province vary from 200 to 300 increasing gradually to 400 in the colorado plateau region q sub 0 valuesmore in the columbia plateau vary from 200 to 400 q sub 0 values increase very rapidly along the central and southern rocky mountains from 400 to 800 east of the rocky mountains q sub 0 values increase gradually in the interior plains to a maximum value of around 1300 in the mississippi embayment region farther east q sub 0 values decrease gradually to an almost constant value of 1000 along the appalachian mountains coastal regions of eastern and northeastern united states have a crustal q sub 0 value between 900 to 700 regions of north central and gulf coastal plains show low q sub 0 values ranging from 600 to 400 and less the source factor b f sub p a measure of the intensity of scattering was obtained for several different regions of the continental united states regions of high q sub 0 values exhibit low intensity of scattering less

distribution of porphyry deposits in the eurasian continent and their corresponding tectonic settings in the eurasian continent there are three huge metallogenic belts of cu and mo porphyry deposits comprising the paleozoic central asian ore belt in the north the tethyan eurasian ore belt of jurassic to cenozoic age in the southwest and the east margin ore belt of the eurasian continent of jurassic to cretaceous age in the east the latter is considered to be part of the vast circum pacific ore belt some of the main features of the spatial temporal distribution of cu and mo porphyry systems and related geodynamic processes of the three metallogenic belts are described in particular the key role of postsubduction related porphyry ore systems is emphasized comprising collisional and post collisional cu mo porphyry deposits during the geological history of the eurasian continent the recurrent feature of these ore systems and related felsic rocks is their derivation from partial melting of stagnant or residual oceanic slabs and mixing with a variable amount of crustal material during magma ascent to shallower levels 2013 published by elsevier ltd

mechanisms of seismic attenuation in the crust scattering and anelasticity in new york state south africa and southern california the envelopes of high frequency seismograms from earthquakes in new york state south africa and southern california are analyzed to determine how much of the observed attenuation of shear waves in the crust is caused by anelasticity and how much is produced by scattering from small scale heterogeneities for seismograms from new york and south africa there is a systematic enrichment of high frequency energy that develops in the coda relative to the direct s or l sub g waves the author uses the growth with source receiver distance of the high frequency energy in the coda relative to the direct wave to estimate the scattering attenuation of the crust and the relative time decay of high frequency energy in the coda to determine the anelastic attenuation using the estimate of l sub g wave q as a constraint he finds that the scattering q in the crust of new york is either independent of frequency or increases with frequency f slower than f sup 0 3 a similar analysis for south africa indicates that scattering is the major cause of the observed s wave attenuation of high frequency energy 30 hz at local distances 100 km for southern california the extent of the scattering attenuation is unclear from the data more although the relatively steep coda decay of southern california implies that anelastic attenuation is stronger there than in new york or south africa for southern california and new york state the 3 hz coda q taken from the late coda 50 110 s is comparable to the l sub g wave q however the 3 hz coda q for south africa over these lapse times is about 5 times the estimated l sub g wave q for all three areas the frequency dependence of the coda q does not match the frequency dependence of the s wave q and for new york and south africa it changes with lapse time less

accurate estimation of seismic source parameters of induced seismicity by a combined approach of generalized inversion and genetic algorithm application to the geysers geothermal area california the accurate determination of stress drop seismic efficiency and how source parameters scale with earthquake size is an important issue for seismic hazard assessment of induced seismicity we propose an improved non parametric data driven strategy suitable for monitoring induced seismicity which combines the generalized inversion technique together with genetic algorithms in the first step of the analysis the generalized inversion technique allows for an effective correction of waveforms for attenuation and site contributions then the retrieved source spectra are inverted by a non linear sensitivity driven inversion scheme that allows accurate estimation of source parameters we therefore investigate the earthquake source characteristics of 633 induced earthquakes mw 2 3 8 recorded at the geysers geothermal field california by a dense seismic network i e 32 stations more than 17 000 velocity records we find a non self similar behavior empirical source spectra that require an source model with 2 to be well fit and small radiation efficiency sw all these findings suggest different dynamic rupture processes for smaller and larger earthquakes and that the proportion of high frequency energy radiation and the amount of energy required to overcome the friction or for the creation of new fractures surface changes with earthquake size furthermore we observe also two distinct families of events with peculiar source parameters that in one case suggests the reactivation of deep structures linked to the regional tectonics while in the other supports the idea of an important role of steeply dipping faults in the fluid pressure diffusion

insights into the structure and tectonic history of the southern south island new zealand from the 3 d distribution of p and s wave attenuation

differential analysis of coda q using similar microearthquakes in seismic gaps part 2 application to seismograms recorded by the parkfield high resolution seismic network abstract nearly two thirds of the microseismicity occurring at parkfield california consists of repeating clusters of closely located events exhibiting waveform cross correlation values exceeding 0 95 this observation coupled with a high probability for an m 6 earthquake within the next decade working group on california earthquake probabilities 1988 make this segment of the san andreas fault system a prime location to search for temporal variations in coda q associated with crustal changes that may occur during the earthquake cycle the coda comparison analysis method described in part 1 of this study aster et al 1996 is applied to data from four borehole stations of the parkfield high resolution seismic network hrsn for the period january 1987 through february 1994 we examine 21 of the nearly 300 repeating clusters observed to date the restriction of the data set to only the most highly similar sources is observed to be critical small differences in the source process even for event pairs with centroid locations within approximately 20 m significantly increase the spurious noise level in the parameter estimates absolute 68 confidence bound estimates obtained on the repeatability of coda q for all microearthquake pairs are 10 for frequencies below 20 hz tighter constraints are obtainable by reconstructing the temporal history of coda q from the first difference measurements between microearthquake pairs these functional reconstructions show that the mean value of coda q has not varied by more than approximately 5 from 3 to 30 hz at the 1 level during the study period however other observables such as an increased level of microseismicity suggest that a preparatory stage for the next parkfield earthquake has begun indicating that coda q is so far showing no sign of sensitivity to preparatory processes at parkfield

multistage exhumation of the menderes massif western anatolia turkey structural analyses along selected transects across the menderes massif and incorporation of existing data have resulted in a synthetic cross section across southwestern turkey the tectonic interpretation has been combined with 40ar 39ar laser probe experiments on two syn kinematic white mica populations which respectively predate and overprint documented early miocene deformational fabrics our results indicate that the regional extension had initiated by eocene oligocene times a 36 2 ma 40ar 39ar age derived from white mica which formed during a regionally observed northward directed tectonic transport suggests that the extension was contemporaneous with the tectonic emplacement of mid crustal continental basement alternatively the age may relate to the regional cooling of the basement sequence and thus postdates the tectonic emplacement in the latter scenario the analysis fails to solve the present ambiguity on the pan african or alpine affinity of the northward directed transport further exhumation of basement rocks is characterized by a dominant displacement along the north dipping gediz detachment at the northern margin of the massif which developed under ductile conditions in the early miocene by partial exploitation of older zones of weakness which originated from an earlier phase of basement emplacement youngest semi ductile activity along the gediz detachment has been recorded as having a 7 1 ma 40ar 39ar age derived from syn kinematic white mica in the top of the detachment following the initiation of the ductile gediz detachment an antithetic semibrittle and south dipping buyuk menderes detachment had developed in the center of the massif which together with the gediz detachment accommodated further doming of the central part of the menderes massif and controlled the architecture of the surrounding supradetachment basins