a new attenuation relation for strong ground motion in japan based on recorded data following the 1995 hyogo ken nanbu kobe earthquake the japanese government in an effort to prevent future earthquake disasters installed networks consisting of a large number of strong motion observation stations further national seismic hazard maps were made available to the public on an internet website in march 2005 by the headquarters for earthquake research promotion however these maps indicate only the local seismic intensity for japan as empirically con verted from predicted peak velocity in consolidated soils for various applications other strong motion indexes such as the response spectral acceleration are required in this study a database of whole japanese strong ground motion records between 1963 and 2003 is established in order to identify a new standard attenuation relation for japan for response acceleration as well as peak value it is usually very difficult to determine a suitable model form due to the large variability of strong motion data and correlation among the model variables because the strong coupling of variables in an attenuation model and the statistical power of the data is often not large enough to determine the necessity of these parameters therefore in this study our model has only three variables earthquake magnitude shortest distance to the seismic fault plane and focal depth to improve predictions given by the model site correction terms are adopted and additional terms for correcting regional anomalous seismic intensity with respect to the base model are determined the good fit between the model and observed strong motion records suggests that the new model is reasonably robust

source spectra and spectral attenuation of seismic waves from mexican earthquakes and evidence of amplification in the hill zone of mexico city it is well known that seismic waves are enormously amplified at lake bed sites with respect to hill zone sites in mexico city it has been suggested that even hill zone sites suffer amplification in this paper we use eight recent well recorded earthquakes to determine spectral attenuation of seismic waves and to quantify the suggested amplification in the hill zone results show that indeed spectral amplitudes at these sites are roughly 10 times greater than expected for sites outside mexico city at similar hypocentral distances this implies that lake bed sites are amplified by a factor of 100 to 500 at some frequencies between 0 2 to 0 7 hz the source spectra retrieved from the regression analysis agree well with those obtained from epicentral recordings alone for two of the largest earthquakes ms 8 1 and 7 6 whose seismic moments are well determined and whose source spectra can be patched in a very broad band of frequencies 0 015 to 20 hz we observe clear deviation from an 2 model the spectra at intermediate frequencies from about 0 05 to 2 hz show a sag whether the observed spectra deviate from an 2 model for events with ms 6 depends on the reliability of the reported long period seismic moments if they are considered reliable then these events also deviate from the model if however the reported seismic moments of smaller events are ignored then the observed spectra can be fitted well with the 2 model

dynamic rupture of asperities and stress change during a sequence of large interplate earthquakes in the mexican subduction zone we investigate the spatial and temporal variations of shear stress due to the successive failures over an extensive segment of the mexican subduction zone during a sequence of large interplate earthquakes that occurred over a period of 13 yr for this purpose we develop 3d dynamic rupture models incorporating a shal lowly dipping fault located above the subducting plate the spatial distribution of dynamic stress drop over the fault has been estimated for each of the events through an inversion procedure using some of the previously derived kinematic fault param eters as observational constraints the results revealed quite heterogeneous stress changes during these earthquakes coming from medium to high dynamic stress drop due to the rupture of a few patch like asperities and from stress increase in between and around them two weak asperities located southeast of the michoacan segment were ruptured first by the 1979 petatlan event the 1981 playa azul event ruptured two asperities in the central zone with a stress drop higher than 80 bars the largest 1985 michoacan earthquake resulted from the rupture of two large size strong asperities located at both sides of the 1981 fault zone with high stress drop of 80 to 100 bars and from another two asperities at depth two days after this largest event two asperities were broken during the zihuatanejo aftershock in the southeastern adjacent zone many after shocks of these large events tend to be distributed in the zones of stress increase outside the asperities while only small numbers of aftershocks have been observed within these asperity zones it appears that several major asperities that existed in this extensive segment have been ruptured successively so as to fill unbroken gaps on the plate interface thus the stress change left over from the previous earthquake has dominant effects on the next event in this subduction zone

empirical ground motion relations for subduction zone earthquakes and their application to cascadia and other regions ground motion relations for earthquakes that occur in subduction zones are an important input to seismic hazard analyses in many parts of the world in the cascadia region washington oregon northern california and british columbia for example there is a significant hazard from megathrust earthquakes along the subduction interface and from large events within the subducting slab these hazards are in addition to the hazard from shallow earthquakes in the overlying crust we have compiled a response spectra database from thousands of strong motion record ings from events of moment magnitude m 5 8 3 occurring in subduction zones around the world including both interface and in slab events the 2001 m 6 8 nis qually and 1999 m 5 9 satsop earthquakes are included in the database as are many records from subduction zones in japan kyoshin net data mexico guerrero data and central america the size of the database is four times larger than that available for previous empirical regressions to determine ground motion relations for subduc tion zone earthquakes the large dataset enables improved determination of attenu ation parameters and magnitude scaling for both interface and in slab events soil response parameters are also better determined by the data we use the database to develop global ground motion relations for interface and in slab earthquakes using a maximum likelihood regression method we analyze regional variability of ground motion amplitudes across the global database and find that there are significant regional differences in particular amplitudes in cascadia differ by more than a factor of 2 from those in japan for the same magnitude distance event type and national earthquake hazards reduction program nehrp soil class this is believed to be due to regional differences in the depth of the soil profile which are not captured by the nehrp site classification scheme regional correction factors to account for these differences are proposed for cascadia and japan the results of this study differ significantly from previous analyses based on more limited data and have important implications for seismic hazard analysis the ground motion relations predict that a great megathrust earthquake m 8 at a fault distance of about 100 km would produce pseudoacceleration psa 5 damped horizontal component on soil sites of about 110 cm sec 2 at 0 5 hz 660 cm sec 2 at 2 5 hz and 410 cm sec 2 at 5 hz with a peak ground acceleration of about 180 cm sec 2 these damaging levels of motion would be experienced over a very large area corresponding to a rectangular area about 300 km wide by 500 km long large in slab events m 7 5 would produce even higher psa values within 100 km of the fault but the in slab motions attenuate much more rapidly with distance thus the hazard posed by moderate to large in slab events such as the 2001 nisqually earth quake is modest compared to that of a cascadia megathrust earthquake of m 8 in terms of the area that would experience damaging levels of ground motion

using borehole records to estimate magnitude for earthquake and tsunami early warning systems this paper presents a new application of the ground motion prediction equations gmpes to estimate the event magnitude for earthquake and tsunami early warning systems this technique incorporates borehole strong motion records along with surface recordings provided by kiban kyoshin network kik net stations we analyzed strong ground motion data from earthquakes with moment magnitude m ranging from 5 0 to 8 1 recorded by kik net stations provided by japan s national research institute for earth science and disaster prevention nied over the interval of 1998 to 2010 we used 2160 strong ground motion accelerograms with peak ground acceleration pga larger than 10 cm s2 recorded by borehole seismographs and 890 waveforms with pga larger than 80 cm s2 recorded by surface seismographs to derive gmpes for pga and peak ground velocity pgv in japan these gmpes are used as the basis for regional magnitude determination predicted magnitudes from pga values mpga and predicted magnitudes from pgv values mpgv were defined separately for borehole and surface recordings mpga and mpgv strongly correlate with the moment magnitude of the event provided that at least 20 records for each event are available the results show that mpgv from borehole data has the smallest standard deviation among the estimated magnitudes and provides an accurate early assessment of earthquake magnitude we demonstrate that incorporation of borehole strong ground motion records immediately available after the occurrence of large earthquakes significantly increases the accuracy of earthquake magnitude estimation and improves earthquake and tsunami early warning systems performance

source parameters of earthquakes in eastern and western north america based on finite fault modeling the ground motion from large earthquakes is often predicted based on finite fault modeling in which the fault plane is discretized into small independently rupturing subfaults the radiation from all subfaults is summed at the observation point despite the success of the method in matching observed ground motion char acteristics the physical interpretation of the subfaults has remained largely unclear and a rationale for the choice of the subfault attributes has been lacking two key parameters the subfault size and the maximum slip velocity on the fault govern the amplitude of the source spectrum at intermediate and high frequencies respec tively we determined these key source parameters on an event by event basis for all well recorded moderate to large earthquakes in western north america wna by fitting simulated to observed response spectra we compare the values of these source parameters with those obtained previously for eastern north america ena and the michoacan mexico earthquakes a total of 26 modeled events we find that the characteristic subevent size increases linearly with moment mag nitude in an apparently deterministic manner the subevent size relationship obtained for wna is not statistically different from that obtained for ena in both regions the subevent size follows the trend of log dl 2 0 4 m 4 m 8 where dl is the subfault size in km this trend agrees well with independent studies by somerville et al 1999 and aki 1992 in which the characteristic size of the patches asperities or barriers on earthquake faults was determined these results indi cate that large earthquakes should be viewed as a sequence of smaller events that comprise the large rupture interestingly the characteristic size of these constituent small events appears to be directly related to the size of the overall rupture the slip velocities determined for all 26 earthquakes vary in a narrow range from about 0 25 to 0 60 m sec with a mean of 0 40 m sec and standard deviation of 0 09 m sec the slip velocities for the ena events are distributed randomly over this range while those for the wna region appear to exhibit a decreasing trend with increasing magnitude our results indicate that a generic region independent earthquake source model for engineering prediction of strong ground motions can be developed

an estimate of shear wave q of the mantle wedge in mexico we utilize earthquake recordings at two broadband seismographs located on the coast of the gulf of mexico to estimate q of the mantle wedge from the data at a station situated in the laguna verde nuclear power plant lvig about 100 km northwest of veracruz and at the eastern edge of the mexican volcanic belt we estimate an upper bound of shear wave q of the mantle wedge q f 120 f 0 75 0 1 f 10 hz as compared with q f 251 f 0 58 for the average path through subducted slab and continental lithosphere curiously the estimated q of the mantle wedge at station scig which is located on the yucatan block is about the same as the average q in southern mexico there are several possible explanations for the difference 1 very few recordings at scig 2 a site effect at scig masking the effect of low q of the mantle wedge and 3 relatively high mantle q beneath the yucatan block the third possibility is supported by surface wave tomography that reveals a thick cold mantle lithosphere below the yucatan block and near absence of mantle lithosphere in the backarc region of central mexico a higher density of seismographs along the gulf coast is needed to resolve these issues our study predicts diminished ground motions at the laguna verde nuclear power plant if the seismic waves pass through the mantle wedge or traverse below the popocatepetl or orizaba volcanoes

evaluating a kinematic method for generating broadband ground motions for great subduction zone earthquakes application to the 2003 mw 8 3 tokachi oki earthquake abstract we compare broadband synthetic seismograms with recordings of the 2003 m w 8 3 tokachi oki earthquake to evaluate a compound rupture model in which slip on the fault consists of multiple high stress drop asperities superimposed on a background slip distribution with longer rise times low frequency synthetics 1 hz stochastic synthetics using a matched filter at 1 hz we show that this compound rupture model and overall approach accurately reproduces waveform envelopes and observed response spectral accelerations sas from the tokachi oki event we find that sufficiently short subfault rise times i e electronic supplement additional waveforms and subevent slip distributions

an empirical relationship between seismic attenuation and velocity anomalies in the upper mantle we use recent p wave attenuation q 1 and velocity vp tomographic models of the tonga fiji region to obtain an empirical relation between attenuation and velocity for the upper mantle the attenuation and velocity anomalies show a strong inverse correlation allowing the determination of an empirical relationship the relationship is similar to a predicted relation derived from laboratory experiments on peridotite and dunite assuming the observed anomalies result from temperature variations the results here suggest that the observed anomalies are generally consistent with the effect of temperature and demonstrate that the combination of velocity and attenuation data provides powerful constraints on the physical state of upper mantle materials we find that the chosen geotherm and activation energy has a strong effect on the position of the solidus within the seismic data

site amplifications for generic rock sites seismic shear wave velocity as a function of depth for generic rock sites has been estimated from borehole data and studies of crustal velocities and these velocities have been used to compute frequency dependent amplifications for zero attenuation for use in simulations of strong ground motion we define a genetic rock site as one whose velocity at shallow depths equals the average of those from the rock sites sampled by the borehole data most of the boreholes are in populated areas for that reason the rock sites sampled are of particular engineering significance we consider two genetic rock sites rock corresponding to the bulk of the borehole data and very hard rock such as is found in glaciated regions in large areas of eastern north america or in portions of western north america the amplifications on rock sites can be in excess of 3 5 at high frequencies in contrast to the amplifications of less than 1 2 on very hard rock sites the consideration of unattenuated amplification alone is computationally convenient but what matters for ground motion estimation is the combined effect of amplification and attenuation for reasonable values of the attenuation parameter k 0 the combined effect of attenuation and amplification for rock sites peaks between about 2 and 5 hz with a maximum level of less than 1 8 the combined effect is about a factor of 1 5 at 1 hz and is less than unity for frequencies in the range of 10 to 20 hz depending on t using these amplifications we find provisional values of about ao 70 bars and k 0 0 035 sec for rock sites in western north america by fitting our empirically determined response spectra for an m 6 5 event to simulated values the borehole data yield shear velocities 033o of 618 and 306 rrdsec for rock and soil sites respectively when averaged over the upper 30 m from this we recommend that v30 equals 620 and 310 m sec for applications requiring the average velocity for rock and soil sites in western north america by combining the amplifications for rock sites and the site factors obtained from our analysis of strong motion data we derive amplifications for sites with 17 3o 520 m sec nehrp class c corresponding to a mix of rock and soil sites and v3o 310 and 255 m sec average soil and nehrp class d sites respectively for the average soil site the combined effect of amplification and attenuation exceeds a factor of 2 0 for frequencies between 0 4 and about 4 hz with a peak site effect of 2 4 the peak of the nehrp class d site effect is 2 7

biostratigraphy and sedimentology of upper permian and lower triassic strata at masore western slovenia abstract upper permian and lowermost triassic strata of the masore section in western slovenia have been restudied by means of bio and lithostratigraphy this section is mainly characterized by a carbonate succession of the bellerophon formation deposited in a shallow marine ramp environment that was located in the western part of the paleotethys the permian triassic boundary ptb transition is marked by laminated microbialites stromatolites interpreted to reflect a deeper ramp environment the conodont elements recovered enabled the recognition of the hindeodus praeparvus zone of the uppermost permian upper changhsingian in the bellerophon formation gondolellids are documented in the ptb transitional interval with microbial microfacies whereas the isarcicella isarcica zone lower griesbachian lower triassic is recognized in the tectonically separated werfen formation just above the microbial microfacies part of the section the lowermost part of the microbialites is characterized by late permian species of foraminifers indicating that at least this part of the section is still upper permian

new species of the conodont genus hindeodus and the conodont biostratigraphy of the permian triassic boundary interval abstract four new species of the conodont genus hindeodus hindeodus eurypyge sp nov hindeodus inflatus sp nov hindeodus sp nov a and hindeodus sp nov b are described from the permian triassic transition in south china our study confirms the first appearance of hindeodus parvus at the gssp level base of bed 27c at meishan however at shangsi the first occurrence of h parvus is about 4 5 m above the event boundary analysis of conodont biostratigraphy of the meishan d section and the shangsi section suggest significant differences between the two sections these include the absence of h changxingensis wang from the shangsi section and the approximately 4 5 m of the shangsi section that contains h priscus kozur h latidentatus kozur and h eurypyge n sp below the first occurrence of h parvus these differences may be accounted for most easily by suggesting that there is a minor depositional hiatus at the permian triassic boundary gssp level as based on the first appearance of the conodont hindeodus parvus in meishan section d taxonomic re evaluation of hindeodus pa elements indicates that species of the genus can be broadly separated into two groups based on the morphology of the posterior portion of the element and on growth patterns the stable pa element morphology of hindeodus first developed in the carboniferous was replaced by a complex of rapid evolutionary change in the latest permian and early triassic with as many as 11 valid species of the genus in the permian triassic boundary interval which are probably descendants of only two species h typicalis and h n sp b we suggest that the dramatic change in conodont biofacies observed at the p t boundary in south china from neogondolella dominated faunas to hindeodus dominated faunas was caused by the introduction of a high component of silt beginning in bed 27 at meishan and bed 28 at shangsi that tipped the environmental balance in favor of hindeodus and isarcicella over neogondolella clarkina species we contend that hindeodus species were adaptable to higher levels of turbidity than neogondolella clarkina species and hence at meishan and shangsi it was not a matter of a drastic increase in the abundance of hindeodus but an exclusion of neogondolella

newly imaged shape of the deep seismic zone within the subducting pacific plate beneath the hokkaido corner japan kurile arc arc junction 1 the geometry of the deep seismic zone associated with the subducting pacific plate beneath the north american plate in the hokkaido corner japan kurile arc arc junction has been investigated based on the hypocenters accurately relocated by a dense local seismographic network with three dimensional p and s wave velocity structures the model suggests that the lateral changes in the dip of the subduction zone are more rapid than previously believed we found that the deep seismic zone in the pacific plate dips at 20 to 30 on the side of the japan arc the dip angle increased in a narrow region around 143 144 e by 10 to 20 and the dip was 40 to 50 on the side of the kurile arc in the transitional zone around 143 144 e an unusual distribution of microearthquakes has been discovered within the pacific plate which was located on a near vertical plane with an area of 50 100 km2 with strike that was perpendicular to the kurile trench axis this feature was named the tokachi oki slab cracking zone we suggest that this is a slab cracking zone torn by the extensional stress due to the rapid lateral changes in the dip of the subduction zone the slab cracking zone may possibly grow into the large disruption or tear of the slab in the future

ground motion attenuation source and site effects for the 26 september 2003 m 8 1 tokachi oki earthquake sequence abstract on 26 september 2003 a megathrust earthquake of m 8 1 occurred at the kurile trench northern japan we used accelerograms recorded on more than 300 k net stations ranging in distance from 40 to 500 km to determine source attenuation and site effects for the mainshock and four aftershocks with m 7 3 6 4 5 9 and 5 5 the analyses are based on linear regression applied to the fourier spectra data of each event the ground motion attenuation for all the events can be modeled using an assumed geometric spreading coefficient b 1 1 0 with an associated anelastic attenuation model given by an apparent q 135 f 0 76 by using dummy variables in the regression site amplifications relative to national earthquake hazard reduction program nehrp c sites are determined for d and e sites nonlinear site amplification was investigated for the m 8 1 data but was not significant in determining the overall amplification factors fourier spectra data were corrected to a reference near source distance and site condition hard rock the source spectrum for each event was compared to that of the theoretical brune model spectrum in order to compute seismic moment and stress drop seismic moments obtained in this manner agree with those of other studies stress drops range from 100 to 200 bars with no apparent dependence on magnitude the mainshock stress drop was 120 bars a similar value 100 bars was calculated for an interface aftershock events with the highest stress drops near 200 bars may have been in slab events

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

ground motions for earthquakes in southwestern british columbia and northwestern washington crustal in slab and offshore events regional ground motion generation and propagation must be charac terized to adequately assess seismic hazard in the cascadia region of southwestern british columbia and northwestern washington the ground motion issues are par ticularly complex because of the contributions to hazard from five distinct types of events all of which behave differently in terms of their ground motion propagation characteristics 1 shallow earthquakes occurring in the continental crust 2 shallow earthquakes occurring offshore in oceanic crust 3 earthquakes occurring within the subducting juan de fuca slab beneath the continent e g puget sound 4 earth quakes occurring within the subducting juan de fuca slab at the edge of the continent e g transitional events along the west coast of vancouver island and 5 great subduction earthquakes on the interface between the subducting juan de fuca plate and the overriding north american plate in this study empirical data recorded within the cascadia region are used to evaluate the source and attenuation characteristics of ground motion amplitudes from the first four of these event types crustal off shore in slab and transitional and examine their implications for regional ground motion relations for crustal earthquakes in cascadia a simple application of the hybrid empirical approach is used to suggest appropriate regional ground motion relations the ground motions are obtained by multiplying california ground motion relations by a frequency dependent factor to account for regional differences in crustal amplifica tion the developed ground motion relations for cascadia earthquakes are in rea sonable agreement with recorded ground motions in the region the proposed rela tions are the first region specific ground motion relations to be developed for the cascadia region and they provide a useful alternative to california relations for use in seismic hazard analysis

along arc and back arc attenuation site response and source spectrum for the intermediate depth 8 january 2006 m 6 7 kythera greece earthquake an m 6 7 intermediate depth 66 km in slab earthquake occurring near the island of kythera in greece on 8 january 2006 was well recorded on networks of stations equipped with acceleration sensors and with broadband velocity sensors all data were recorded digitally using recording instruments with resolutions ranging from almost 11 to 24 bits we use data from these networks to study the distance dependence of the horizontal component fourier acceleration spectra fas and horizontal component pseudoabsolute response spectral acceleration psa for pur poses of simulating motions in the future we parameterize the distance decay using several forms of the geometrical spreading function for each of which we derive q as a function of frequency by extrapolating the distance decay back to 1 km we obtain a reference spectrum that can be used in future simulations this spectrum requires a more complicated spectral shape than the classic single corner frequency model in particular there appears to be an enhancement of motion around 0 2 0 3 hz that may be due to the radiation of a 3 5 sec pulse from the source we infer a 0 value of about 0 055 sec for rock stations and a stress parameter in the range of 400 600 bars we also find distinctive differences in the site response of stations on soft soil and soil both the fas and the 5 damped psa amplifications have similar peak amplitudes about 2 and 4 for soil and soft soil sites respectively relative to the rock sites at similar frequencies between about 0 4 and 2 0 hz with the soft soil amplifications peaking at somewhat lower frequencies than the soil amplifications one of the most distinctive features of the data is the clear difference in the motions for along arc and back arc stations with the former being significantly higher than the latter over a broad range of frequencies at distances beyond about 250 km the motions from the kythera earthquake are roughly comparable to those from intermediate depth earthquakes elsewhere but they appear to be significantly higher than those from re cordings of shallow earthquakes in greece of comparable magnitude and hypocentral distance

near source attenuation of peak horizontal acceleration strong motion data recorded within 50 km of the rupture zone were used to study near source attenuation characteristics of horizontal peak ground acceleration for worldwide earthquakes of magnitudes 5 0 to 7 7 the data base consisted of 229 horizontal components of peak acceleration recorded from 27 earthquakes including the 15 october 1979 imperial valley earthquake these data were found to be adequately represented by the functional relationship pga a exp b m r c m d where pga represents the mean of the peak values scaled from the two horizontal components of each recording m is richter magnitude and r is distance from the fault rupture zone peak acceleration was found to be lognormally distributed with a standard error representing a 45 per cent increase in the median estimate the regression analysis statistically confirmed the results of earthquake simulation studies that have predicted peak acceleration to become independent of magnitude and distance in the near field an extensive sensitivity study showed that predictions based on our attenuation relationships are stable with respect to reasonable model and parameter variations an analysis of residuals was used to investigate the behavior of peak acceleration with respect to various earthquake site and recording parameters the more significant findings being 1 a similarity in the level of acceleration recorded on soil or rock 2 larger than average accelerations recorded at sites located on shallow soils or in areas of steep topography 3 larger than average accelerations associated with earthquakes having reverse fault mechanisms and 4 lower than average accelerations recorded in large embedded structures

predicted ground motions for great interface earthquakes in the cascadia subduction zone ground motions for earthquakes of moment magnitude m 7 5 9 0 on the cascadia subduction zone interface are simulated based on a stochastic finite fault model and used to estimate average response spectra for firm site conditions in vancouver victoria and seattle we also express the response spectra as ground motion prediction equations gmpes for cascadia events the simulations are calibrated by modeling the wealth of ground motion data from the m 8 1 tokachi oki earthquake sequence of japan adjustments to the calibrated model are made to consider average source attenuation and site parameters for the cascadia region we perform best estimate simulations for a preferred set of input parameters typical results suggest mean values of 5 damped pseudoacceleration in the range from about 100 to 200 cm sec2 at frequencies from 1 to 4 hz for firm ground conditions in vancouver victoria and seattle uncertainty in stress drop causes uncertainty in simulated response spectra of about 50 uncertainties in the attenuation model produce even larger uncertainties in response spectral amplitudes a factor of about 2 at 100 km becoming even larger at greater distances it is thus important to establish the regional attenuation model for ground motion simulations furthermore combining data from regions with different attenuation characteristics in particular japan and mexico into a global subduction zone database for development of global empirical gmpes may not be a sound practice time histories of acceleration for the stochastically simulated motions are provided for reference sites in vancouver victoria and seattle an alternative set of motions based on lightly modifying real recordings from the tokachi oki earthquake to match expected conditions for cascadia cities are also provided these alternative records have similar spectral content to the simulated motions but contain additional complexity and more realistic phasing the provision of alternative record sets allows users to conduct studies to determine the importance of these effects for structural response

crustal structure across the kurile trench off south eastern hokkaido by airgun obs profiling summary seismic refraction profiles were shot across the kurile trench south east of hokkaido japan the experiment in a typical island arc trench system where the pacific plate subducts beneath hokkaido was designed to investigate the transition of crustal structure from oceanic basin to continental slope across the trench high resolution data were obtained from a 9 litre airgun and multi obs system they were processed through a series of operations digitization filtering slant stacking t sum inversion two dimensional ray tracing and comparison with synthetic seismograms a typical oceanic structure composed of an unconsolidated sedimentary layer p wavespeed of 1 8 2 2 kms 1 thickness of 0 5 1 km layer 2 3 1 5 8 kms 1 1 2 km with a large wavespeed gradient and relatively homogeneous layer 3 6 0 6 8 kms 1 5 km is found on the oceanic side of the trench observations of shear waves converted at the boundary between the sedimentary layer and layer 2 gave compressional to shear wavespeed ratios of about 7 0 for the topmost sedimentary layer and 1 73 1 77 for layers 2 and 3 the transition of structure occurs slightly landward of the trench axis and thick low wavespeed materials p wavespeed of 2 5 4 7 km s 1 persist beneath the continental slope the density profile derived from our wavespeed structure is consistent with published free air gravity anomaly data the general crustal structure in the southern part of the kurile trench is similar to that of the japan trench off sanriku however the distribution of the thick low wavespeed materials on the continent side differs between the two trench regions these materials are more abundant in the kurile trench region as is also inferred from the gravity anomaly pattern the variability of the gravity anomaly on the continental side along the trench axis suggests that the distribution of these materials changes even within a single trench system the seismic activity inferred from s p time distribution at each obs is high near the trench and low in the oceanic basin beyond about 30 km from the trench axis as well as on the continental side where thick low wavespeed materials exist an activity which seems to occur exactly in the narrow transition zone dividing the typical oceanic crust and the thick low wavespeed materials in the continental side structure is found

ground motions from subduction zone earthquakes a total of 258 horizontal components of accelerogram data recorded at soil sites during thrust normal and strike slip earthquakes occurring in seven subduction zones around the pacific ocean were analyzed the results of statistical analyses of 5 per cent damped pseudo velocities psv computed from these accelerograms at 10 periods t between 0 1 and 4 sec indicated no significant differences in the average psv levels of the thrust normal and strike slip data from the northern honshu zone each of these groups of northern honshu data which together comprised one half of the total data base were fit equally well by the same attenuation model the analyses also revealed that at intermediate periods 0 8 t 3 sec the psv observed at stiff soil sites within the northern honshu nankai kuril mexico and alaska zones were on the average significantly greater than the psv observed at similar sites in the peru northern chile and new britain bougainville zones this observation indicates that differences in the source and or travel path characteristics between the two groups accounted for the differences in psv independent evidence supporting source differences is the correlation noted between psv in this period band and the characteristic source complexities for these zones which hartzell and heaton inferred from the teleseismic data of the larger magnitude earthquakes certain anomalous tectonic characteristics of the new britain bougainville zone were noted that may have contributed in some systematic manner to the relatively unusual spectral characteristics of the ground motions recorded on stiff soil sites within this zone some of the differences in the psv among the zones at intermediate and long periods were probably the result of differences in local geologic characteristics geology greatly influenced the mexican psv data from soft soil sites to a lesser extent geology probably affected the alaskan data which were recorded mostly on deep stiff soils and the new britain bougainville data recorded at yonki which is underlain by softer soil deposits

inelastic seismic demand of real versus simulated ground motion records for cascadia subduction earthquakes nonlinear dynamic analysis of structures requires strong ground motion time histories accelerograms as input the inherent scarcity of recorded ground motions for specific conditions magnitude distance region and site makes utilization of alternatives unavoidable such alternatives include simulated records and modified real records there are many simulation methods available but there is often a preference to using stochastic simulation methods if justifiable due to the ease with which many records can be simulated in a generic way however there are concerns that such simulated records may not produce similar nonlinear response in structures as real records or modified real records due to the lack of realistic phasing and other record characteristics including peaks and troughs effects and response spectral shape effects this study investigates peak nonlinear responses of inelastic single degree of freedom systems with different hysteretic characteristics subjected to sets of stochastically simulated records lightly modified real records and scaled real records the former two of which were proposed by atkinson and macias 2009 as representative of expected ground motions for cascadia subduction earthquakes of m 8 5 at vancouver victoria and seattle we conclude that 1 the peak nonlinear responses due to the modified records and the scaled real records are similar if the peaks and troughs effects and response spectral shape effects are taken into account adequately in the choice of scaling factors for the real records and 2 the peak nonlinear responses due to the simulated and modified records are similar these findings though obtained based on limited sets of ground motion records are in agreement with previous studies and highlight the need for judicious choices in cases involving the scaling of records the results also suggest that stochastically simulated records may be an appropriate way to capture overall response potential for both linear and nonlinear structural systems at least over a range of periods from 0 1 to 2 sec

a detailed subduction structure in the kuril trench deduced from ocean bottom seismographic refraction studies abstract in 1983 we conducted an ocean bottom seismograph obs experiment in the southernmost part of the kuril trench beneath which the pacific plate is subducting under hokkaido island japan the aim of this experiment was to determine crust and upper mantle structure from the oceanic basin to the continental slope by dense seismic refraction profiling using explosives and airguns the total length of the profiles was 560 km along which ten obs s were deployed the observed data were of good quality which enabled us to obtain a detailed velocity structure of the active margin down to 20 30 km we constructed a velocity structure model by ray tracing and amplitude modeling in the oceanic basin the crust has a typical oceanic structure characterized by three layers with p wave velocities of 1 8 3 8 6 5 and 6 5 7 0 km s the velocity gradient in layer 3 increases downward from 0 075 to 0 10 s 1 the moho discontinuity was well constrained by clearly observed p n and p m p phases the total thickness of the oceanic crust was determined to be 8 km and almost constant in the oceanic basin the p wave velocity is 7 9 km s beneath the moho discontinuity which increases downward with a rather small velocity gradient 0 015 0 03 s 1 beneath the continental slope we found relatively low velocity 2 5 to 5 5 5 8 km s material the oceanic moho discontinuity associated with the subducting plate was traced down to a depth of 25 km our seismic data strongly suggest that oceanic layer 2 is smoothly subducting and does not break up to form a wedge structure this result is in remarkable contrast with the velocity structure in the active margin of the ryukyu trench area about 1000 km south of the present experimental area where we found a 12 km thick prominent low velocity wedge is situated 50 150 km landward from the trench axis on the seaward side of the wedge the surface of the igneous basement undulates severely the wedge was probably formed by materials of oceanic origin such a difference in velocity structure suggests that the subduction mechanism in the trench area differs from region to region in the northwestern pacific

the shape of ground motion attenuation curves in southeastern canada the shape of the attenuation curve of the fourier spectrum of acceleration is established for southeastern canada from empirical data the dataset is comprised of 1200 digital vertical component seismograms from 100 earthquakes recorded on 30 stations of the eastern canada telemetered network the distance range of the observations is 10 to 1700 km focal depths are from 5 to 30 km results indicate that the attenuation curve has three distinct sections at distances less than 70 km corresponding to attenuation of the direct wave amplitudes decay slightly more rapidly than 1 r r 1 1 between 70 and 130 km where the direct wave is joined by sms spectral amplitudes are approximately constant beyond 130 km corresponding to the lg phase amplitudes decay at a rate that is consistent with r 0 5 and q 670 f 0 33 the findings support the hypothesis of burger et al 1987 that postcritical reflections from the moho discontinuity play an important role in determining the shape of the attenuation curve however the influence of sms is subtle allowing the shape to be approximated by simple functional forms for example the commonly assumed bilinear form r 1 r 0 5 with frequency dependent q fits well if the transition from direct wave to lg spreading is placed at approximately 60 km a linear form r 1 over all distances with constant q 2000 also provides a satisfactory fit overall we find little evidence for the dependence of attenuation on focal depth or tectonic province

combination of acceleration sensor and broadband velocity sensor recordings for attenuation studies the case of the 8 january 2006 kythera intermediate depth earthquake on 8 january 2006 an intermediate depth earthquake occurred at the western part of the hellenic trench close to the island of kythera southern greece this is the first intermediate depth earthquake in the broader aegean area that has produced such an extensive set of useful recordings as it was recorded by the main permanent seismological networks and numerous acceleration sensors operating in greece as well as by egelados a large scale temporary amphibian broadband seismological network deployed in the southern aegean area an effort to combine all the available data broadband velocity and acceleration sensor was made to study the properties of ground motion attenuation of this earth quake the combination of both types of data revealed interesting properties of the earthquake wave field which would remain hidden if only one type of data was used moreover the data have been used for a validation of existing peak ground motion empirical prediction relations and the preliminary study of the very inhomogeneous attenuation pattern of the southern aegean intermediate depth events at both near and far source distances

a microbialite carbonate crust at the permian triassic boundary in south china and its palaeoenvironmental significance a 1 m thick carbonate crust layered and commonly domal caps crinoidal limestones on reef complexes of the top permian changxing formation in the huaying mountains eastern sichuan china the crust s stratigraphic level lies at a sharp change in facies and is overlain by poorly fossiliferous laminated micrites and shales of the lower triassic feixianguan formation the crust therefore appears to coincide with the end permian extinction event although the dating of the strata is currently imprecise the crust is composed mostly of digitate carbonate locally thrombolitic with remnant lobate fabric and resembles microbialites but is mostly recrystallised and a microbial origin is unconfirmed it is enclosed in micrite with pyrite crystals ostracode and other shell debris the crust is absent from interreef areas previous interpretations of karstification and calcrete formation are not upheld and the facies were deposited under water overlying sediments are low energy with abundant ferroan calcite and pyrite reflecting anoxia associated with rising sea level various interpretations of the crust are possible 1 it was organic and microbia grew preferentially on topographic highs of reef tops 2 microbia were a disaster biota in the absence of grazers 3 microbia took advantage of favourable conditions for calcification associated with a rapidly rising environmental co2 content during the late permian 4 the crust was an inorganic precipitate associated with co2 rich water microbial crusts are rare after the cambrian but whether this crust is organic or not its presence in these strata reinforces the view that oceanic atmospheric conditions in the permian triassic boundary interval were unusual

three dimensional seismic attenuation structure beneath the japanese islands and its tectonic and thermal implications a three dimensional 3 d seismic attenuation structure beneath the japanese islands is determined by inversion of seismic intensity data the result clearly reveals a remarkable contrast in the attenuation structure and reflects the lateral variation of thermal structure beneath the japanese islands for the inversion the method developed by hashida and shimazaki is used the intensity which is assumed to be a measure of the maximum acceleration of the s wave at the observation point is inverted to estimate the attenuation structure and the acceleration at the seismic source the data consist of about 15 000 intensity readings for about 800 earthquakes reported by the japan meteorological agency between 1951 and 1983 by combining 3 d structures of eight districts in japan 3 d attenuation maps consisting of three layers are constructed to a depth of 90 km the obtained structure reveals the following features first a distinct difference exists in the crustal structure between ne and sw japan in ne japan low q high attenuation areas on the continental side of the arc are dominant whereas some high q low attenuation areas exist on the pacific side of the arc in sw japan except for the kyushu district high q areas are dominant and small low q areas exist mainly on the pacific coast these crustal features generally continue down to the uppermost mantle second the obtained crustal structure shows that attenuation is age dependent low qareas correspond to the distribution of quaternary volcanic materials and high q areas correspond to the geological provinces where pre cenozoic rocks are distributed since the thermal structure strongly depends on the crustal age this feature suggests that the attenuation structure reflects the thermal structure third in the upper mantle low q loci are found which correspond to the distribution of active and other quaternary volcanoes forming the arc volcanic chain it should be noted that even on the continental side of the volcanic front these loci do not exist beneath areas where no volcano exists this suggests that the upper mantle attenuation is controlled by the existence of upwelling diapirs which are considered to lie beneath a volcano or a group of volcanoes fourth high q zones in the upper mantle exist on the pacific side of the volcanic front along the kurile northeast honshu arc and along ryukyu arc the high q mantle lying above the sinking slab seems to reflect a cooling effect of the subducting cold oceanic plates the thickness of the lithosphere may reach 60 km or more in such outer arcs although the thickness has been considered to be about 30 km or so in sw japan where the high q uppermost mantle also lies a thick lithosphere of about 60 km may exist possible thermal cross sections are proposed for ne and sw japan based on the obtained 3 d attenuation structure and other geophysical considerations in the uppermost mantle of ne japan a higher temperature is expected than in sw japan the thermal structures reflect the difference of tectonic settings in the two regions such as the subducting plate overriding lithosphere and volcanic activity

stochastic finite fault modeling of ground motions from the 1999 chi chi taiwan earthquake application to rock and soil sites with implications for nonlinear site response the stochastic method for simulating strong ground motions from finite faults is applied to the records of the 1999 chi chi taiwan earthquake the method involves discretization of the fault plane into smaller subfaults each of which is assigned an x 2 spectrum the contributions from all subfaults are empirically atten uated to the observation site and summed to produce the synthetic acceleration time history the method is initially calibrated against the data recorded at 24 rock sites located within 7 120 km from the mainshock hypocenter and providing a broad azimuthal coverage of the fault plane the accuracy of the simulations is quantified through the model bias defined as the logarithm of the ratio of the observed to simulated spectrum averaged over all stations the calibrated model for the chi chi event has a near zero average bias in reproducing the ground motions at rock sites in the frequency range from 0 1 to 20 hz an unusually low value is found for the radiation strength factor s controlling the high frequency radiation level and directly related to the maximum slip velocity on the fault compared with the mean value found for north american earthquakes this result reflects the observed low peak ground ac celerations of the chi chi mainshock and physically its lower than usual slip ve locities the calibrated model is then used to simulate soil site site class d records using the linear response assumption the simulated soil site input motions are amplified by the weak motion amplification functions estimated by the spectral ratio technique from available aftershock records this analysis reveals an average reduction in strong motion amplification to about 0 5 0 6 of that in weak motions with an ac celeration threshold for detectable nonlinearity near 200 300 cm sec 2 however the derivation of soil site specific weak motion amplification was limited by the amount of aftershock data available further improvement in the quantification of nonlinear soil response during the chi chi earthquake may be possible with the release of additional aftershock datasets

an empirical study of earthquake source spectra for california earthquakes we generalize source path and site effects for california earthquakes as functions of magnitude and distance based on regression analysis of 1000 fourier acceleration spectra from 43 california earthquakes in the moment magnitude range from 4 4 to 7 4 recorded at rupture distances from 1 to 200 km empirically derived source spectra for california earthquakes are generally inconsistent with the spectral shape implied by a brune omega squared point source model this is manifested by magnitude and frequency dependence of the brune model parameters for ex ample the brune stress parameter that best matches the data at high frequencies decreases from a value of about 120 bars at m5 5 to a value near 50 bars at m7 5 at frequencies below 1 hz though source spectra have much lower spectral ampli tudes than predicted by the brune point source model for these values of stress this discrepancy grows with increasing magnitude finite fault simulations indicate that this is a consequence of the breakdown of the validity of the point source approxi mation for large ruptures a stochastic finite fault model in which the fault is dis cretized as a number of subfaults each of which is represented by a brune omega squared point source correctly matches the observed spectral shapes and amplitudes the spectral decay parameter kappa representing average near surface attenuation of high frequency motion at rock sites increases with increasing magnitude from values near 0 035 sec at m5 5 to 0 050 sec at m7 5 magnitude dependence of kappa may be interpreted as evidence of nonlinearity for typical california sites subjected to strong ground motion comparisons of our empirical source spectra for california to corresponding spec tra for eastern north america suggest that the spectral amplitudes are similar in the two regions for low frequency motions f 2 hz for m5 5 f 0 5 hz for m7 5 for equivalent crustal conditions the eastern events appear to have enhanced high frequency near source amplitudes relative to the california events this is particularly pronounced for large magnitude earthquakes

early triassic calcimicrobial mounds and biostromes of the nanpanjiang basin south china stanley s model 1988 proposed that a permiantype reef fauna survived the early triassic reefless period in yet undiscovered refuges in the ancestral pacific ocean and then reappeared as the builders of middle triassic reefs flugel 1994 in contrast suggested that the middle triassic reefbuilding fauna are not holdovers from the permian but bear only a superficial resemblance to permian fossils recent publications reflect a consensus that the early triassic lacked reefs and reef mounds although some authors acknowledged the possibility that reef like structures may have existed in poorly explored areas such as south china and russia senowbari daryan et al 1993 flugel 1994 it is shown herein that calcimicrobial framework mounds and biostromes existed in the early triassic in the nanpanjiang basin of south china organic framework in this paper refers to a three dimensional biologically constructed network of calcified fossils that forms a rigid mass and supports an interconnected network of internal cavities that were open during accumulation although the calcimicrobial frameworks discussed herein are much smaller than frameworks of modern metazoan reefs the term framestone is more appropriate for these fabrics than other reef rock terms such as bindstone or bafflestone embry and klovan 1971 these calcimicrobial mounds and biostromes are important as the first organic framestones documented from the early triassic

the relationship between late cenozoic tectonic events and stress field and basin development in northeast japan the regional tectonic stress field basin development and crustal deformation of the ne japan arc in the interval between 32 ma to the quaternary can be synthesized based on dike vein and fault orientation data as well as on the compilation of the regional geology an extensional stress field became prevalent from 32 ma and major normal faulting started at 25 20 ma which resulted from back arc rifting normal faulting trending nearly parallel to the arc propagated from the present japan sea coast to the forearc side following the trenchward migration of the main volcanic field from 20 to 15 ma normal faults with an oblique trend to the arc developed due to the counterclockwise rotation of ne japan the rapid clockwise rotation of sw japan since 16 ma produced a nw se directed transtensional stress regime in the ne japan arc due to crustal stretching associated with this pull apart movement the back arc side of the ne japan arc subsided rapidly to middle bathyal environments after the termination of the opening of the japan sea at about 14 ma a neutral stress regime prevailed which included phases of both weak extension and compression lithospheric cooling eventually led to thermal subsidence of the back arc region and igneous underplating caused uplift of the axial zone of the volcanic arc the increase in velocity of the westward motion of the pacific plate at around 4 ma produced strong compression across the arc reactivating most of the miocene normal faults and uplifting the volcanic arc the greatest crustal shortening occurred in areas that were stretched the most in the miocene within the volcanic arc which implies tectonic inversion

from blunt to cutting distinguishing alternating method flakes in early stages on rounded blanks abstract two main knapping strategies can be used to start bifacial reduction on a lithic cobble or nodule the alternate strategy in which first one face is knapped and then the other and the alternating strategy in which both faces are removed in the same sequence interspersing core about turns between strikes flaking reduction of spherical and elliptical blanks cobbles or nodules is a common knapping process documented in many archaeological records rounded and thick edges require different fracture parameters and give rise to constraints in terms of viable knapping methods when analysing abandoned cores it is only possible to see the last strikes so it is important to know how they were shaped or exploited in the earlier knapping stages in order to understand the entire reduction process as cortical flakes are the direct evidence of the first reduction phases we undertook an experimental programme for the purpose of comparing the first flakes generated using the alternate and alternating knapping strategies we have focused our efforts on identifying and diagnosing distinctive features produced by each strategy in the first or cortical flakes our study indicates that several platform attributes can be considered as diagnostic features to differentiate between the alternate and alternating knapping strategies and that this kind of analysis can be translated to archaeological assemblages

regional path effects on seismic wave propagation in central mexico we present results of the analysis of a set of seismograms recorded in a temporary array of seven broadband seismic stations located in central mexico our purpose was to investigate path effects on ground motion in central mexico for earthquakes occurring in the subduction zone along the pacific coast all our stations were located on rock nineteen earthquakes 3 6 m c 4 9 recorded by all seven stations were analyzed the results show that path effects result in significant amplification and an increase of the duration of the seismic motion at two stations located in the central part of the transmexican volcanic belt tvb analysis of the records for periods larger than 5 sec shows that the 3d crustal structure acts as an efficient wave guide for surface waves coming from distances greater than 200 km only for paths oriented north south or east west in the band of 2 6 sec we observe large amplification and an increase in the duration of ground motion associated to the regional propagation of higher modes of surface waves after correlating our results with recent geological and gravimetric studies we suggest that this amplification could be due to the impedance contrast of low velocity volcanic rocks of the tvb overlying higher velocity limestones if we are right the increase of ground motion duration would result from mode conversion at the southern boundary of the tvb these path effects in the 2 to 6 sec period band are very important for ground motion in mexico city because the very soft surficial deposits in that basin amplify greatly ground motion in this same period band

the 1993 kushiro oki japan earthquake a high stress drop event in a subducting slab a spatial slip distribution of the 1993 kushiro oki earthquake mw 7 6 is undoubtedly constrained using near field data and the detailed aftershock distribution this earthquake has peculiar features in that the slip on the fault plane is restricted within an extremely small area about 40 km 20 km between the upper and lower planes of the double seismic zone in the subducting slab beneath hokkaido the total seismic moment averaged slip and stress drop in this area are 3 3 1020 nm 5 5 m and 4 2 107 pa respectively this earthquake indicates that the region of the slab between the planes of the double seismic zone beneath hokkaido is strong enough to sustain a stress of about 4 107 pa the slip motion of this event is consistent with retrograde slab migration along the southern kuril trench and may represent a process by which retrograde motion of subducting slabs could occur

nonparametric description of peak acceleration as a function of magnitude distance and site in guerrero mexico this article describes the peak accelerations observed on a network of strong motion accelerographs above the subduction zone in guerrero mexico as a function of magnitude and hypocentral distance our empirical description differs from regression analysis however in that it produces a table of values of peak acceleration for selected values of m and r and an interpolation rule to obtain peak acceleration at intermediate values with this approach the existence and extent of saturation of peak acceleration as magnitude increases is dictated by the data and unlimited flexibility is allowed in the distance dependence of the peak acceleration this nonparametric approach does not allow extrapolation beyond the range of the data and is thus most useful when the data spans a large magnitude and distance range after 7 yr of recording the digital guerrero accelerograph network has obtained enough data to test the concept the records include events with magnitudes ranging from under 3 to 8 1 with all magnitudes recorded at distances ranging from nearly directly above the rupture to distances where acceleration has become too small to trigger the instruments the data used in this study consist of 528 recordings each three components from 146 earthquakes that occurred between 1985 and 1990 all but one station are on rock sites since all the accelerograms are recorded by one of 30 stations there is an average of about 18 records for each station the results suggest that at short distances about 14 to 25 km from the fault as magnitude increases the peak horizontal acceleration saturates at about 20 g however unlike small earthquakes peak accelerations decrease very slowly with increased distance from the rupture in a large magnitude station corrections for peak acceleration reduced the rms misfit by about 15 for the horizontal component by 12 for the vertical component and by 21 for the ratio for some stations horizontal corrections are close to vertical corrections but others show very different site effects on horizonal and vertical components the ratios of peak vertical acceleration to peak horizontal acceleration show a very weak tendency to decrease as magnitude increases and this tendency is further reduced at most distances after correction for average site effects the average value of this ratio is 0 70 before the station correction after these corrections for 55 events with known stress drop the residual between the predicted peak acceleration and the observed peak acceleration is correlated with stress drop although scattered the observations are consistent with a theoretical prediction that amax 0 80

the technology and significance of the acheulian giant cores of gesher benot ya aqov israel abstract the presence of very large lithic artifacts at the acheulian site of gesher benot ya aqov is one of the site s most distinctive and enlightening features basalt giant cores and their products modified by a variety of core methods and found in association with different hominin activities occur throughout the stratigraphic sequence of the site in this paper we describe the giant artifacts of gesher benot ya aqov together with their reduction sequence from the nature and acquisition of the raw material through the shaping of the cores to the discarded cores and their typical waste products we then discuss the significance of these finds and their implications for understanding the site and its varied activities as well as for acheulian cognitive abilities and behavior during the early middle pleistocene on the margins of the paleo lake hula

what attributes are important for the measurement of assemblage reduction intensity results from an experimental stone artefact assemblage with relevance to the hoabinhian of mainland southeast asia abstract our understanding of variation in the technology of flaked stone artefacts from mainland southeast asia during the terminal pleistocene and holocene periods has improved little since they were originally labelled hoabinhian in 1932 chronological and geographical variation has been described in terms of typological differences but there are few anthropological explanations of lithic diversity and change an analysis of an experimentally produced hoabinhian assemblage is undertaken here to show which flake variables are significant indicators of assemblage reduction intensity the results show that recording the presence of overhang removal interior platform angle and percentage of dorsal cortex will provide robust data on the extent of assemblage reduction a new method for detecting assemblage variation based on the location of dorsal cortex on flakes is also presented and experimentally verified these methods are designed to take advantage of the typical geometry and reduction patterns of hoabinhian assemblages these findings provide another tool to build anthropological explanations of hoabinhian archaeology

the world s oldest stone artefacts from gona ethiopia their implications for understanding stone technology and patterns of human evolution between 2 6 1 5 million years ago the systematic archaeological and geological survey and excavations at gona between 1992 1994 led to the discovery of well flaked stone artefacts which are currently the oldest known from anywhere in the world more than 3000 surface and excavated artefacts were recovered at 15 localities documented east and west of the kada gona river based on radioisotopic dating 40 ar 39 ar and magnetostratigraphy the artefacts are dated between 2 6 2 5 million years ago ma eg10 and eg12 from east gona are the most informative with the highest density providing the best opportunity for characterizing the oldest assemblages and for understanding the stone working capability of the earliest tool makers slightly younger artefact occurrences dated to 2 4 2 3 ma are known from hadar and omo in ethiopia and from lokalalei in kenya cut marked bones dated to 2 5 ma from bouri in ethiopia are now providing important clues on the function of these artefacts in addition australopithecus garhi known from contemporary deposits at bouri may be the best candidate responsible for the oldest artefacts surprisingly the makers of the gona artefacts had a sophisticated understanding of stone fracture mechanics and control similar to what is observed for oldowan assemblages dated between 2 0 1 5 ma this observation was corroborated by the recent archaeological discoveries made at lokalalei because of the similarities seen in the techniques of artefact manufacture during the late pliocene early pleistocene it is argued here that the stone assemblages dated between 2 6 1 5 ma group into the oldowan industry the similarity and simplicity of the artefacts from this time interval suggests a technological stasis in the oldowan 2000 academic press

an evaluation of the applicability of current ground motion models to the south and central american subduction zones the applicability of existing ground motion prediction equations gmpes for subduction zone earthquakes is an important issue to address in the assessment of the seismic hazard affecting the peru chile and central american regions few predictive equations exist that are derived from local data and these do not generally meet the quality criteria required for use in modern seismic hazard analyses this paper investigates the applicability of a set of global and regional subduction ground motion models to the peru chile and central american subduction zones distinguishing between interface and intraslab events in light of recently compiled ground motion data from these regions strong motion recordings and associated metadata compiled by arango strasser bommer boroschek et al 2011 and arango strasser bommer hernandez et al 2011 have been used to assess the performance of the candidate equations following the maximum likelihood approach of scherbaum et al 2004 and its extension to normalized intraevent and interevent residual distributions developed by stafford et al 2008 the results of this study are discussed in terms of the transportability of gmpes for subduction zone environments from one region to another with a view to providing guidance for developing ground motion logic trees for seismic hazard analysis in these regions online material tables summarizing the statistics for the scherbaum et al 2004 scoring system

examining stage and continuum models of flake debris analysis an experimental approach abstract flake debris produced from a number of flintknapping experiments is used to explore stage and continuum models of lithic reduction using metric attributes flakes produced during core reduction are separated from those produced during tool production theoretically this should allow the utilization of continuum approaches in the analysis of archaeological assemblages that represent a mix of reduction strategies i e core reduction and tool production further continuum based analyses are refined by providing a standardized scale although this work demonstrates the potential utility of a continuum based model for analysing archaeological lithic assemblages stage analyses retain utility and can be fruitfully used in conjunction with the refined continuum model developed here

magnitude estimation for the 2011 tohoku oki earthquake based on ground motion prediction equations this study investigates whether real time strong ground motion data from seismic stations could have been used to provide an accurate estimate of the magnitude of the 2011 tohoku oki earthquake in japan ultimately such an estimate could be used as input data for a tsunami forecast and would lead to more robust earthquake and tsunami early warning we collected the strong motion accelerograms recorded by borehole and free field surface kiban kyoshin network stations that registered this mega thrust earthquake in order to perform an off line test to estimate the magnitude based on ground motion prediction equations gmpes gmpes for peak ground acceleration and peak ground velocity pgv from a previous study by eshaghi et al in the bulletin of the seismological society of america 103 2013 derived using events with moment magnitude m 5 0 1998 2010 were used to estimate the magnitude of this event we developed new gmpes using a more complete database 1998 2011 which added only 1 year but approximately twice as much data to the initial catalog including important large events to improve the determination of attenuation parameters and magnitude scaling these new gmpes were used to estimate the magnitude of the tohoku oki event the estimates obtained were compared with real time magnitude estimates provided by the existing earthquake early warning system in japan unlike the current operational magnitude estimation methods our method did not saturate and can provide robust estimates of moment magnitude within 100 s after earthquake onset for both catalogs it was found that correcting for average shear wave velocity in the uppermost 30 m v text s 30 improved the accuracy of magnitude estimates from surface recordings particularly for magnitude estimates of pgv mpgv the new gmpes also were used to estimate the magnitude of all earthquakes in the new catalog with at least 20 records results show that the magnitude estimate from pgv values using borehole recordings had the smallest standard deviation among the estimated magnitudes and produced more stable and robust magnitude estimates this suggests that incorporating borehole strong ground motion records immediately available after the occurrence of large earthquakes can provide robust and accurate magnitude estimation

the permian triassic boundary in western slovenia idrijca valley section magnetostratigraphy stable isotopes and elemental variations stable isotope analyses of carbonate 13ccarb and total organic carbon toc 13corg together with geochemical analyses of 54 major minor and trace elements and magnetic susceptibility measurements were carried out on whole rock samples of the undisturbed permian triassic p tr limestone boundary sequence in the idrijca valley w slovenia at the p tr boundary there is a 0 8 cm thick clayey marl layer ptb showing a characteristic magnetic susceptibility pulse and considerable enrichment in most major minor and trace elements the p tr transition is characterized by 1 an abrupt decrease in sedimentation rate from 32 to 5 cm 100 ka 2 a well known prominent negative excursion of 13ccarb and 13corg reflecting global perturbations in the carbon cycle and 3 the drastic disappearance of typically upper permian marine fauna although the shape of the 13ccarb curve indicates gradual long term change across the p tr boundary the sharp negative 13corg anomaly within an interval from 30 cm below to 6 cm above the boundary suggests an interruption of those gradual processes our observations for selected redox sensitive elements mo u v and zn abundances for organic carbon and sulphur and the rare earth elements ree distribution in the boundary sequence as well as the shape of the ce ce curve suggest that oceanic anoxia was typical of the upper permian and that the transition to oxygenated conditions occurred at the p tr boundary oxygenation at the p tr transition is coincidental with the terminal phase of the upper permian marine regression the shape of the ce ce curve indicates that the redox environmental conditions changed again in the earliest triassic resulting once more in oxygen deficient conditions

forearc versus backarc attenuation of earthquake ground motion understanding of the attenuation of seismic wave amplitudes with distance is a crucial issue for ground motion prediction equations and seismic hazard analysis in this study we empirically evaluate the influence of regional geologic structure in particular the attenuation effects of traveling through a volcanic arc region forearc versus backarc attenuation in northern japan we perform regression analysis of fourier amplitude spectra fas of five well recorded japanese events that occurred very close to the line formed in map view by the volcanic arc this provides an approximately symmetrical distribution of stations for each event relative to the volcanic front forearc stations lie to the east of the front while backarc stations lie to the west to compare the characteristics of shallow and deep events we have included both crustal and in slab events in our dataset based on inspection of the data we assume a hinged bilinear geometric spreading model with a fixed slope of 1 out to a distance of 50 km with slope of 0 5 thereafter for all events our results show with a very high level of confidence that high frequency attenuation is greater in the backarc direction the q values for forearc regions q 240 at 1 hz increasing to q 3890 at 10 hz are about a factor of 2 larger than those for backarc regions q 196 at 1 hz increasing to q 1669 at 10 hz at high frequencies implying much stronger attenuation as waves travel through the volcanic crustal structure to the backarc stations the separation of forearc and backarc travel paths results in a significant reduction in the standard deviation of ground motion predictions by as much as 0 05 log10 units which has important implications for hazard analyses in subduction zone regions

oldowan reduction sequences methodological considerations abstract transport of resources is a major feature of oldowan hominin technological adaptations comparisons between different oldowan localities often employ measures of transport that are based on artefact attributes as proxies for the intensity of raw material utilization the technological flake category system toth n 1985 oldowan reassessed a close look at early stone artifacts journal of archaeological science 12 pp 101 120 has been used extensively to infer the relative intensity of lithic reduction within oldowan assemblages here we use a large experimental sample to test the relationship between a flake s stage in a reduction sequence and various quantitative attributes we demonstrate how many previously described attributes are affected by initial core size we then develop a multiple linear regression model that incorporates several variables to predict the placement of a flake within a generalized reduction sequence the model is then applied to oldowan assemblages in the koobi fora formation which explores the strengths and weaknesses of different methods of investigating reduction intensity on an assemblage level

stochastic finite fault simulations of the 2011 tohoku japan earthquake we performed stochastic finite fault simulations for the moment magnitude m 9 0 11 march 2011 tohoku earthquake at kik net sites using the exsim algorithm motazedian and atkinson 2005 atkinson et al 2009 boore 2009 the average response spectra of the simulated ground motions were calculated and compared with observed ground motions to determine whether stochastic finite fault modeling can reproduce key features of the recorded motions to account for variations in source characteristics we examined three rupture process models a single event model with random slip distribution a single event model with prescribed slip distribution yagi 2011 see data and resources 1 and a multiple event model with five strong motion generation areas kurahashi and irikura 2011 the analysis results indicate that the single event models can model the high frequency response spectra values well but result in significant model bias in the low frequency range by contrast the multiple event model produces ground motions that are in good agreement with the observations in both high and low frequency ranges furthermore the multiple event model can capture temporal characteristics of observed ground motions including multiphase arrivals of major seismic wave groups importantly the calibrated exsim model for the 2011 tohoku earthquake can be used to produce predicted ground motions in other regions such as the cascadia subduction region of north america by suitable modifications of regional attenuation and site parameters the suitability of the simple stochastic simulation method to prediction of motions for future events the details of which are poorly known makes its calibration to tohoku a useful exercise 1 sec 14