borehole response studies at the garner valley downhole array southern california the garner valley downhole array gvda consists of a set of seven downhole strong motion instruments ranging from 0 to 500 m depth one of the objectives of this experiment is to estimate site response and study wave propagation as the energy travels from the bedrock underneath the site up through the soil column the gvda velocity structure is studied by computing synthetic accelerograms for a small event located at an epicentral distance of 10 km these synthetics simulate well the data recorded at the borehole stations in addition theoretical transfer functions are calculated using the obtained velocity model and compare well with the empirical transfer functions from 54 recorded events it is also observed that the downgoing wave effect is predominant in the first 87 m and is strongly reduced at depth using the velocity structure at gvda and the transfer function results it has also been possible to develop a simple method to compute the incident wave field which is needed in nonlinear site response for instance recently there have been many comparative studies between horizontal to vertical h v spectral ratios and traditional spectral ratios although many of these studies show that h v spectral ratios can reproduce the shape of the site response curve most show differences in the amplitude level in the case of garner valley where we have both surface and multiple borehole instruments we find that this discrepancy in amplitude of the site response estimates is because the vertical component has significant site response associated with it due to s to p conversions that begin in the weathered granite boundary at 87 m depth manuscript received 27 august 2001

a comparison and test of various site response estimation techniques including three that are not reference site dependent abstract we compare various site response estimation techniques using after shock data of the 1989 loma prieta earthquake collected in oakland california because of recent interest in comparing results from weak and strong motion to infer any nonlinearity and between direct s and coda waves we pay particular attention to the uncertainties first sediment to bedrock spectral ratio estimates between pairs of sites are compared with those obtained from various generalized inversion approaches where the source and site effects of multiply recorded events are solved for simultaneously we find that the site amplification factors are very similar among these approaches but that the uncertainties can be significantly different depending on how the data are weighted we also examine and test three site response estimation techniques that do not rely on a reference site to estimate source and path effects the first involves a parameterized source and path effects inversion even when the bedrock data are excluded from consideration this approach is found to reveal the frequency dependence of site response at each of the sediment sites the second technique involves taking horizontal to vertical component spectral ratios receiver function type estimates of shear wave aftershock data these are also found to reveal the frequency dependence of site response at the sediment sites and the results for the bedrock site are relatively flat and near unity the third estimate is formed by taking horizontal to vertical component ratios of ambient seismic noise and these are shown to reveal the fundamental resonant frequency of the sediment sites unfortunately discrepancies exist among all of the site response estimates and with one dimensional predictions with respect to a frequency independent scaling factor nevertheless the highly frequency dependent character of site response is well constrained and the fact that non reference site dependent methods are capable of revealing this is promising for site specific hazard assessments in regions that lack adequate reference sites

three dimensional simulations of ground motions in the san bernardino valley california for hypothetical earthquakes on the san andreas fault three dimensional finite difference simulations of elastic waves in the san bernardino valley were performed for two hypothetical earthquakes on the san andreas fault a point source with moment magnitude m5 and an extended rupture with m6 5 a method is presented for incorporating a source with arbitrary focal mechanism in the grid synthetics from the 3 d simulations are compared with those derived from 2 d vertical cross section and 1 d flat layered models the synthetic seismograms from the 3 d and 2 d simulations exhibit large surface waves produced by conversion of incident s waves at the edge of the basin seismograms from the flat layered model do not contain these converted surface waves and underestimate the duration of shaking the seismograms from the 3 d simulations have larger amplitude coda than do the seismograms from the 2 d case because of the presence of off azimuth surface wave arrivals in the 3 d simulations that are not included in the 2 d simulations snapshots of the wavefield of the 3 d simulation show that these off azimuth arrivals represent surface waves reflected from the edges of the basin the anelastic attenuation of the sediments is a key parameter controlling the overall duration of motion some of the coda energy at rock sites near the basin edges represents leakage of surface wave energy out of the basin for the m6 5 earthquake simulation the largest ground velocities occur where surface waves reflected from the edge of the basin interfere constructively with the trapped waves that follow the direct s wave maps of maximum ground velocity are produced for two directions of rupture propagation the largest velocities occur in localized portions of the basin the location of the largest velocities changes with the rupture propagation direction contours of maximum shaking are also dependent on asperity positions and radiation pattern

evaluation of site response with alternative methods a case study for engineering implications in this paper efficiency of alternative geophysical techniques for site response is evaluated in two sedimentary basins on the north anatolian fault zone for this purpose fundamental frequencies of soils and corresponding amplitudes obtained from empirical horizontal to vertical spectral ratio curves from microtremors weak motions and strong motions are compared with results from one dimensional theoretical transfer functions theoretical transfer functions are computed using s wave velocity profiles derived from array observations of the microtremor wavefield our results are consistent with studies from other regions in that the fundamental frequencies from microtremors weak motions and theoretical transfer functions are mostly in agreement with each other although some discrepancies are observed even though important information about fundamental resonance frequency can be derived from horizontal to vertical spectral ratios observed amplitudes do not yield consistent results with the theoretical amplification factors thus the use of horizontal to vertical spectral ratio amplitudes is not recommended for estimation of amplification factors based on our observations complementary use of alternative methods for site response is recommended

a noble gas study of a granulite sample from the nilgiri hills southern india implications for granulite formation the he and ar isotopic composition of several mineral separates from a 2 5 ga old enderbite sample from the nilgiri hills southern india were analyzed the sample contains abundant high density carbonic fluid inclusions which have been well characterized in previous studies 1 2 on this particular sample garnet contains synmetamorphic primary fluid inclusions while quartz and plagioclase contain re equilibrated secondary inclusions the noble gases were extracted by crushing or heating of the minerals all measured 3he 4he ratios are above the typical value of old crustal rocks which is about 0 01 0 02 times the atmospheric ratio ra fluid inclusions from the crushed garnet sample contain helium with the highest 3he 4he ratio of 2 34 0 36 ra the he excess is mantle derived and cannot be explained by a cosmogenic or nucleogenic 3he rich component the elemental and isotopic ratios of he ne and ar in all minerals can be explained by a combination of elemental fractionation during diffusional loss of noble gases production of radiogenic nucleogenic4he 21ne 22ne and40ar and atmospheric contamination depending on the assumptions made for the evolution of the he trapped in the garnet fluid inclusions we obtain mixing ratios between mantle derived he and crustal he ranging from 1 5 5 to essentially pure mantle he however probably pure mantle he was trapped in the minerals 2 5 ga ago these data suggest that the enderbite sample represents a former mantle derived tonalitic magma which exsolved its volatiles upon crystallization in the lower crust liberation of a huge amount of co2 by similar intrusions together with the heat provided by them might be responsible for the dehydration of the former amphibolite facies rocks to the north bordering the nilgiri hills

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

cosmic ray produced 21ne in terrestrial quartz the neon inventory of sierra nevada quartz separates the study of cosmic ray produced radioactive and stable nuclides on the surface of the earth can provide relevant geomorphological and glaciological information at present the cosmic ray production rates of stable 21ne are not well known this study attempts to remedy the situation by determining the production rate ratio of 21ne and 26al p21p26 in quartz 26al concentrations and p26 rates have previously been investigated for quartz separates of sierra nevada rocks which were brought to the surface by glacial scouring during the tioga period at the end of the last ice age 1 we used splits of the same samples for our studies and found that ne in these rocks represents a mixture of several components trapped ne nucleogenic 21ne and 22ne produced by n reactions in oxygen and fluorine respectively as well as cosmic ray produced ne which is the component of interest in this study the trapped component was substantially lost in one sample w86 12 by crushing and by a density separation of the grain sizes 38 90 m and 90 125 m permitting the resolution of the in situ produced 21ne into cosmic ray spallation and n produced components and the determination of a lower limit to p21p26 in a second sample w86 8 one split contained small enough amounts of nucleogenic 21ne to permit the determination of a reasonable upper limit to p21p26 the two ratio determinations are consistent within error limits and the value adopted 0 65 0 11 2 agrees with ratios observed in extraterrestrial matter apparently p21p26 is thus not very sensitive to the neutron spectrum however the observed production rate ratio is substantially larger than theoretical estimates for si targets reflecting poorly known neutron excitation functions the above p21p26 value coupled to the observed 26al production rate 1 corresponds to a 21ne production rate of p21 21 atoms g 1 a 1 in quartz or to p21 45 atoms g si 1 a 1 at sea level and high latitudes this rate is based on an adopted exposure age of 11 000 yr for our quartz samples

deterministic ground motion scenarios for engineering applications the case of thessaloniki greece abstract in this article we present a deterministic study to estimate seismic ground motions expected in urban areas located near active faults the purpose was to generate bedrock synthetic time series to be used as seismic input into site effects evaluation analysis and loss estimates for the urban area and infrastructures of thessaloniki northern greece two simulation techniques a full wave method to generate low frequency seismograms 1 hz were used to compute time series associated with four different reference earthquakes having magnitudes from 5 9 to 6 5 and located within 30 km of thessaloniki the propagation medium and different source parameters were tested through the modeling of the 1978 thessaloniki earthquake m 6 5 moreover two different nucleation points were considered for each fault in order to introduce additional variability in the ground motion estimates between the two cases the quasi unilateral rupture propagation toward the city produces both higher median peak ground acceleration pga and peak ground velocity pgv values and higher variability than bilateral ones conversely the low frequency ground motion that is peak ground displacement pgd is slightly influenced by the position of the nucleation point and its variability is related to the final slip distribution on the faults of the reference earthquakes and to the location of the sites with respect to the nodal planes of the radiation pattern to validate our deterministic shaking scenarios we verified that the synthetic peak ground motions pga and pgv and spectral ordinates are within one standard deviation of several ground motion prediction equations valid for the region at specific sites we combined the low and high frequency synthetics to obtain broadband time series that cover the entire frequency band of engineering interest 0 25 hz the use of synthetic seismograms instead of empirical equations in the hazard estimates provides a complete evaluation of the expected ground motions both in frequency and time domains including predictions at short distances from the fault 0 10 km and at periods larger than 2 3 sec

a cosmic trip 25 years of cosmogenic nuclides in geology terrestrial cosmogenic nuclides produced by secondary cosmic ray interactions in the atmosphere and in situ within minerals in the shallow lithosphere are widely used to date surface exposure of rocks and sediments to estimate erosion and weathering rates and to date sediment deposition or burial their use has transformed geomorphology and quaternary geology for the first time allowing landforms to be dated and denudation rates to be measured over soil forming time scales the application of cosmogenic nuclides to geology began soon after the invention of accelerator mass spectrometry ams in 1977 and increased dramatically with the measurement of in situ produced nuclides in mineral grains near earth s surface in the 1980s the past 25 yr have witnessed the development of cosmogenic nuclides from their initial detection to their prevalence today as a standard geochronological and geochemical tool this review covers the major developments of the past 25 yr by comparing the state of the field in 1988 with that of today and by identifying key advances in that period that moved the field forward we emphasize the most commonly used in situ produced nuclides measured by ams for geological applications but we also discuss other nuclides where their applications overlap our review covers ams instrumentation cosmogenic nuclide production rates the methods of surface exposure dating measurement of erosion and weathering and burial dating and meteoric 10 be in memoriam devendra lal 1929 2012 whose vision inspired the field

a hybrid method for simulating near source broadband seismograms application to the 2003 bam earthquake mw 6 5 the main objective of this article is to simulate the three components of near source ground shaking recorded at bam station close to the causative fault during the destructive the 2003 bam earthquake where were strongly influenced by rupture directivity effect a hybrid technique composed of the theoretical green s function finite element and finite difference method proposed by spudich et al 1987 2003 compsyn and a 2 based finite fault approach proposed by beresnev and atkinson 1998a finsim are used for generating seismograms at low and high frequencies respectively a genetic algorithm technique is developed for minimizing the differences between the recorded and simulated data incorporating parameters within a predefined upper lower bound s values previously estimated for main shock by other investigators two different faulting models consist of a straight line segment and a straight line segment followed by a slightly north eastward branch are used the simulated three component seismograms at bam station in terms of elastic response spectra are validated by comparing the simulated time series with those of the observed data moreover the pulses involved in the recorded time series due to the rupture directivity are estimated and compared with those of the observed data a sensitivity analysis is performed for recognizing the influence of model parameter changes such as focal mechanism strike dip and rake rise time rupture velocity and hypocenter location on the simulated seismograms relatively good match of the simulated and observed time series particularly the two faulting models confirm the potentiality of the proposed technique and the suitability of seismological model parameters used this technique can be used for specific site hazard analysis of the bam region and linear nonlinear dynamic analysis of structures where were damaged during the bam earthquake particularly for retrofitting the well known international adobe buildings of arg e bam

rupture process of the 1999 november 12 duzce turkey earthquake deduced from strong motion and global positioning system measurements summary we use the strong motion data recorded at near fault accelerometers combined with global positioning system gps measurements to infer the space and time evolution of the mw 7 2 1999 november 12 duzce turkey earthquake we confirm that the rupture is subshear towards the west whereas it overpassed the shear speed towards the east the mechanism of the earthquake is predominantly right lateral on a 65 north dipping fault the strike slip we infer represents at least 75 of the total seismic moment we stress that the use of strong motion data allows us to constrain a strong spatial variation of the slip direction during faulting to the west of the hypocentral region the slip is oblique accompanied by a significant normal component in the central and eastern part of the activated fault the slip is almost pure right lateral this result is consistent both with the surface offset observations and with the long term morphology of the fault neither strong motion data nor gps data can resolve the complexity of the eastern termination of the duzce rupture

diffusion of cosmogenic3he in olivine and quartz implications for surface exposure dating abstract thein situ production of3he in surface rocks by cosmic ray induced nuclear reactions offers an important geochronological tool to evaluate helium loss problems in this technique cosmogenic3he diffusivities were measured in quartz and olivine by incremental heating at 150 600 c arrhenius temperature dependences were observed in both minerals with similar activation energies ea 25 4 kcal mole logd0 3 7 0 9 in olivine andea 25 2 0 9 logd0 0 2 0 4 in quartz and imply very low diffusivities when extrapolated to environmental temperatures less than 10 18 cm2 s in quartz and 10 22 cm2 s in olivine at 20 c these low diffusivities suggest helium loss will not significantly affect cosmogenic helium exposure dating for time scales on the order of 106 years in quartz and 109 years in olivine provided large 2 mm sample grains are used exposure ages obtained with smaller grains need to be corrected for diffusive helium loss and equations are provided for this purpose cosmogenic3he diffuses more than 100 times faster than trapped magmatic3he in olivine or radiogenic4he in quartz the mechanisms responsible for these differences have yet to be determined but may involve both trapping processes at mineral defects and enhanced mobility associated with spallation produced crystal damage therefore it is possible that helium diffusivities may depend on a sample s cosmic ray exposure or radiogenic production history whatever the precise mechanism the higher mobility of3he suggests that incremental heating will be useful in separating cosmogenic helium from magmatic or radiogenic helium in future studies comparison of the diffusivity results with total cosmogenic3he contents of different quartz size fractions for an antarctic quartzite suggests that he loss may have occurred more rapidly than predicted by the laboratory measurements nonetheless retention of cosmogenic3he is quite high equivalent to more than a million years of exposure and cosmogenic3he geochronology is feasible in this and other quartz containing rocks

cosmogenic neon in recent lavas from the western united states the absolute cosmogenic production of 21ne 21nec and 3he 3hec in olivine fo81 is measured for the well dated tabernacle hill flow values scaled to sea level and high latitude 60 are 45 atoms g yr for 21nec and 109 atoms g yr for 3hec for the past 17 800 years production rates for 21nec are about 50 higher than the theoretical values given by lal 1991 a ratio of 21nec 3hec of 0 41 0 05 is measured in olivines that have a range of 25 in cosmogenic exposure there is no evidence of 3hec loss in samples older than 100 000 years volcanic plagioclase is shown to be a suitable mineral for cosmogenic 21nec dating of surfaces 21nec in co existing plagioclase and olivine phenocrysts have a constant ratio of 0 42 04 in samples with more than 106 atoms of 21nec using all of the 21nec data and the 3hec as a cosmic ray flux monitor production of 21nec in ab36 plagioclase is calculated at 16 8 1 7 atoms g yr for the past 17 800 years the production of 21nec from 23na is estimated at 160 50 atoms g yr at 60 and sea level or equivalent to that on 24mg

cosmogenic 3he in terrestrial rocks the summit lavas of maui we have identified terrestrial cosmic rayproduced 3he in three lava flows on the crest of haleakala volcano on maui 3 km above sea level and 0 5 million years old although these lavas like all oceanic basalts contain primordial 3he from the mantle the cosmogenic component 3hec can be identified unambiguously because it is extractable only by high temperature vacuum fusion in contrast a large fraction of the mantle helium resides in fluid inclusions and can be extracted by vacuum crushing leaving a residual component with 3he 4he ratios as high as 75 those in the atmosphere which can be liberated by melting the crushed grains cosmogenic 3he is present in both olivines and clinopyroxenes at 0 8 1 2 10 12 ml stp g and constitutes 75 5 of the total 3he present the observed 3hec levels require a cosmic ray exposure age of only some 64 000 years much less than the actual age of the lavas if there is no erosion using a model that includes effects of uplift or submergence as well as erosion we calculate an apparent erosion rate of the order of 8 5 m 106 years for the western rim of the summit crater as an example of the application of measurements of cosmogenic rare gases to terrestrial geological problems

role of in situ cosmogenic nuclides 10be and 26al in the study of diverse geomorphic processes the central premises of applications of the in situ cosmogenic dating method for studying specific problems in geomorphology are outlined for simple and complex exposure settings in the light of these general models we discuss the information that can be derived about geomorphic processes utilizing concentrations of in situ produced cosmogenic radionuclides 10be half life 1 5 ma and 26a1 half life 0 7 ma in a variety of geomorphic contexts glacial polish and tills meteorite impact craters alluvial fans paleo beach ridges marine terraces sand dunes and bedrock slopes we also compare 10be 26al data with results obtained by other dating methods we conclude that the technique of measuring in situ cosmic ray produced nuclides holds promise for quantitative studies of processes and time scales in a wide range of geomorphological problems

simulations of ground motion in the los angeles basin based upon the spectral element method we use the spectral element method to simulate ground motion generated by two recent and well recorded small earthquakes in the los angeles basin simulations are performed using a new sedimentary basin model that is constrained by hundreds of petroleum industry well logs and more than 20 000 km of seismic reflection profiles the numerical simulations account for 3d variations of seismic wave speeds and density topography and bathymetry and attenuation simulations for the 9 september 2001 m w 4 2 hollywood earthquake and the 3 september 2002 m w 4 2 yorba linda earthquake demonstrate that the combination of a detailed sedimentary basin model and an accurate numerical technique facilitates the simulation of ground motion at periods of 2 sec and longer inside the basin model and 6 sec and longer in the regional model peak ground displacement velocity and acceleration maps illustrate that significant amplification occurs in the basin

cosmetic isotope analyses applied to river longitudinal profile evolution problems and interpretations the use of cosmogenic isotopes to determine surface exposure ages has grown rapidly in recent years the extent to which cosmogenic nuclides can distinguish between mechanistic hypotheses of landscape evolution is an important issue in geomorphology we present a case study to determine whether surface exposure dating techniques can elucidate the role knickpoint propagation plays in longitudinal profile evolution cosmogenically produced 10be 26al 36cl 3he and 21ne were measured in olivines collected from 5 2 ma basalt flows on kauai hawaii several obstacles had to be overcome prior to the measurement of in situ produced radionuclides including removal of meteoric 10be from the olivine grains discrepancies between the radionuclide and noble gas data may suggest limits for exposure dating approximate surface exposure ages calculated from the nuclide concentrations indicate that large boulders may remain in the hawaiian valley below the knickpoint for hundreds of thousands of years the ages of samples collected above the knickpoint are consistent with estimates of erosion based on the preservation of palaeosurfaces although the exposure ages can neither confirm nor reject the nickpoint hypothesis boulder ages downstream of the knickpoint are consistent with a wave of incision passing upvalley the long residence time off the coarse material in the valley bottom further suggests that knickpoint propagation beneath a boulder pile is necessary for incision of the bedrock underlying the boulders to occur 1997 by john wiley sons ltd

three dimensional scattering by two dimensional topographies three dimensional seismic responses of two dimensional topographies are studied by means of the indirect boundary element method ibem the ibem yields in the presented form very accurate results and has the advantage of low computational cost in ibem diffracted waves are constructed in terms of single layer boundary souces the appropriate green s functions used are those of a harmonic point foce moving along the axis of the topography in a full space obtained reults are compared against those published by other authors examples of simulations are presented for different geometries for different types of incident wave fields and in particular for different arrival angles to the topography to quantitatively study three dimensional effects of the scattering the accuracy of the results makes it possible to analyze them in both the time and drequency domaisn frequency space representations allow identification of difraction and interference patterns in the seismic response of the topography synthetic seismograms are obtained by fourier analysis using timespace domain representations the nature of each of the scattered waves are identified in terms of for example creeping waves and reflected compressional waves

cosmogenic10be 26al and3he in olivine from maui lavas we report the presence of cosmogenic10be and26al in olivines from the maui haleakala basalts in which cosmogenic3he and21ne were discovered based on production rate calibrations in quartz crystals from late pleistocene granite exposures in the sierra nevada the haleakala crater erosion rates derived from10be and26al concentrations agree within 10 and give a mean rate of 12 m myr about 40 greater than the rate of 8 5 m myr previously derived from3he measurements these results establish the feasibility of the simultaneous use of radioactive and stable cosmogenic nuclides for studies of exposure ages and erosion rates in basaltic and andesitic terrains

cosmic ray produced 10be and 26al in antarctic rocks exposure and erosion history we have measured cosmic ray produced t1 2 1 5 million years 10be and t1 2 0 705 million years 26al in purified quartz fractions of selected rock samples from antarctic mountains from these data we calculate 1 mean erosion rates for the limiting case of steady state surface exposure to cosmic rays and 2 minimum exposure ages for the limiting case of no erosion calculated mean erosion rates are very low on the order of a few times 10 5 cm yr we believe the sampling to be sufficient to generalize this result to exposed bedrock in antarctica in favorable cases it is possible to distinguish between the limiting cases steady state erosion seems a better description in such cases most samples including some taken a few meters above the present ice level seem to have been exposed for millions of years without major episodes of burial or abrasion by ice

3he surface exposure dating and its implications for magma evolution in the potrillo volcanic field rio grande rift new mexico usa dating of very young igneous activity has been hampered by lack of suitable chronometers we report here the results of 3he surface exposure dating kurz 1986a b craig and poreda 1986 for lavas from the potrillo volcanic field this field is particularly suited to the technique because it has well preserved young 700 ka surfaces the study applies 3he dating in a systematic manner to a well characterized volcanic field and shows the power of the technique in deciphering both relative and absolute chronologies dates are reproducible to within 14 for different samples from the same surface and are similar to within 8 for samples which based on field relations represent synchronous events cosmogenic 3he21ne confirms that 3he is retained by the samples comparison of the relative chronology with compositional trends of the lavas suggests that eruptive centers within the volcanic field are fed by individual magma chambers ages range from 80 ka to 17 ka consistent with estimates from geomorphology soil profile development and some k ar determinations

slip distribution and stress changes associated with the 1999 november 12 duzce turkey earthquake mw 7 1 the 1999 november 12 duzce earthquake m w 7 1 was apparently the eastward extension of the august 17 izmit earthquake m w 7 4 the duzce event caused heavy damage and fatalities in the cities of duzce and bolu here a finite fault inversion method with five discrete time windows is applied to derive the co seismic slip distribution of the duzce earthquake the fault plane is best modelled as a 40 x 20 km 2 plane with a strike of 262degrees and a dip of 65degrees to the north and that the majority of slip occurred in two distinct patches on either side of the hypocentre implying bilateral rupture the possible triggering of this event by the izmit earthquake is investigated using coulomb stress modelling of all large events since 1943 with the inclusion of secular loading the results show that although the duzce rupture plane was in a stress shadow prior to the izmit earthquake that event caused a significant coulomb stress load taking the duzce fault out of the stress shadow which probably precipitated failure a comparison of the mapped coulomb stress change with the inferred slip shows no correlation between the two finally the stress modelling indicates that the northern branch of the north anatolian fault zone beneath the sea of marmara towards the city of istanbul is presently the most highly loaded segment of the north anatolian fault zone

the cosmic ray produced he 21ne ratio in ultramafic rocks although production of noble gases in meteorites are well studied since many years e g bogard and cressy 1973 the first analysis of cosmic ray produced helium in terrestrial rocks were performed only in 1986 by kurz and by craig and poreda later marti and craig 1987 reported cosmic ray produced neon in summit lavas from maui more data on cosmogenic helium and neon were reported by staudacher and allegre 1991 on ultramafic nodules from asia the absolute production rate of cosmic ray produced helium has been determined by kurz 1986 1987 in olivine rich basalts from hawaii with known k ar or 14c ages the resulting hec production rate is 3 72 10 18cm stp g a this allows cosmogenic he to be used to determine cosmic ray exposure ages of surface samples for neon no such absolute production rate has yet been determined in order to develop a complementary dating method using cosmogenic 21ne staudacher and allegre 1991 measured the cosmogenic he 21ne ratio in ultramafic nodules their value was 1 4 which is significantly smaller than the value of 3 5 obtained in this work here we discuss the cosmogenic he 21ne ratio in view of new noble gas data on olivine separates of oceanites from reunion island and on ultramafic nodules from mongolia

the north anatolian fault a new look dedicated to the memory of three pioneers ihsan ketin sirri erinc and melih tokay and a recent student aykut barka who burnt himself out in pursuit of the mysteries of the north anatolian fault abstract the north anatolian fault naf is a 1200 km long dextral strike slip fault zone that formed by progressive strain localization in a generally westerly widening right lateral keirogen in northern turkey mostly along an interface juxtaposing subduction accretion material to its south and older and stiffer continental basements to its north the naf formed approximately 13 to 11 ma ago in the east and propagated westward it reached the sea of marmara no earlier than 200 ka ago although shear related deformation in a broad zone there had already commenced in the late miocene the fault zone has a very distinct morphological expression and is seismically active since the seventeenth century it has shown cyclical seismic behavior with century long cycles beginning in the east and progressing westwa

holocene rockwall retreat in svalbard a triple rate evolution volumetric calculations of slope deposits direct measurements of rockwall retreat and chronological control based on lichenometry provide a wide range of rockwall retreat rates in svalbard 0 1580 mm ka 1 that appears consistent with previous evaluations from other arctic areas in northwest and central spitsbergen 79 n a triple rate rockwall retreat is suggested for the last two millennia very slow biogenic flaking 2 mm ka 1 moderate retreat due to frost shattering 100 ka 1 and rapid retreat associated with post glacial stress relaxation c 1000 mm ka 1 examination of the distribution of various processes indicates that the holocene retreat of most rockwalls has not exceeded one or two metres bedrock conditions appear to be the main control on retreat rates the massiveness of igneous and metamorphic outcrops widespread in arctic shield areas largely accounts for the slowness of rockwall retreat which on these lithologies is primarily due to chemical and biological processes more rapid rates are usually associated with stress relaxation following glacial surges or with local frost susceptibility of bedrock often where faulting has induced high joint density at such sites rockwall retreat rates are of the same order of magnitude as those reported from alpine areas 1000 3000 mm ka 1 where both bedrock weakening due to tectonic stresses and the greater height of steep rockwalls account for the more rapid rockwall retreat rate 1997 by john wiley sons ltd

three dimensional simulation of a magnitude 7 75 earthquake on the san andreas fault simulation of 2 minutes of long period ground motion in the los angeles area with the use of a three dimensional finite difference method on a parallel supercomputer provides an estimate of the seismic hazard from a magnitude 7 75 earthquake along the 170 kilometer section of the san andreas fault between tejon pass and san bernardino maximum ground velocities are predicted to occur near the fault 2 5 meters per second and in the los angeles basin 1 4 meters per second where large amplitude surface waves prolong shaking for more than 60 seconds simulated spectral amplitudes for some regions within the los angeles basin are up to 10 times larger than those at sites outside the basin at similar distances from the san andreas fault

noble gases in mafic phenocrysts and xenoliths from new zealand we have determined the elemental and isotopic compositions of noble gases in young subduction related phenocrystic olivine and clinopyroxene samples from the taupo volcanic zone central north island new zealand and in behind arc intraplate phenocrystic and xenolithic olivine samples from the northland and auckland volcanic provinces northern north island new zealand helium isotopic ratios range from morb like 3he4he values of about 11 10 6 to lower values of about 6 10 6 consistent with previous measurements of helium isotopic ratios in subduction related samples 40ar36ar and 21ne22ne ratios range from atmosphere like compositions to maximum values of about 700 and 0 033 respectively in contrast most of the 21ne22neratios are generally indistinguishable from atmospheric values the variations in helium neon and argon isotopic ratios are interpreted as resulting from mixing of 1 a a primordial 3he rich component derived from the upper mantle and characterised by morb like 3he4he ratios of about 12 10 6 2 b a radiogenic 4he rich component derived from crustal materials and characterised by a 3he4he ratio of less than 2 10 7 and 3 c a helium poor atmosphere derived component which dominates the heavier noble gases by combining the helium and argon isotopic results it is possible to estimate the relative contribution of each of these three components to the total 40ar observed in each sample based on the present understanding of the origin and evolution of arc magmas a simple qualitative model of the mechanisms which introduce noble gases to the parent magmas of the samples is developed however it remains uncertain whether the atmospheric and crustal derived noble gas components are introduced to the mantle source regions of the magmas by subduction or alternatively are introduced by interactions between the ascending parent magmas and the overlying crust

broadband ground motion simulation within the city of duzce turkey and building response simulation in areas with significant seismic activity and insufficient seismic networks simulated ground motions are required for both seismic hazard and engineering analyses one important task is evaluating the efficiency of the simulated records in building response estimation in this study a hybrid ground motion simulation framework is presented to obtain broadband ground motion time histories of a past major earthquake in duzce turkey the hybrid ground motion simulation framework presented herein is a combination of a discrete wavenumber finite element method for simulating low frequencies and a stochastic finite fault method for the higher frequencies the proposed technique is first validated by the simulation of the 12 november 1999 duzce earthquake m text w 7 1 which occurred in the north anatolian fault zone turkey peak simulated ground motions at selected nodes are then compared against ground motion prediction equations derived with global and local data sets next the spatial distribution of simulated peak ground motion intensities are obtained in the region and compared with the observed damage distribution results demonstrate that the earthquake is simulated effectively despite the limitations in number of stations and velocity models finally to evaluate the simulated records in building response estimation nonlinear time history analyses of three reinforced concrete multi degree of freedom structures are performed with real and simulated records of the 1999 duzce earthquake in the opensees platform the results reveal that reasonable predictions can be made regarding the dynamic response of structures using the records simulated with the approach presented herein

calculated rates of cosmic ray muon produced ne in subsurface quartz 1 interactions of cosmic ray secondaries with subsurface rocks produce both stable 3he 21ne 22ne and radioactive 10be 26al and 36cl cosmogenic nuclides as the production rates by muons of 21ne and 22ne in quartz are not known these can be estimated from published cross sections of analogous reactions separately for fast and slow muon reactions our calculations show that subsurface 21ne is affected mainly by fast muon interactions p f21ne 0 39 0 15 at g 1a 1 vs p 21ne 0 12 0 03 at g 1a 1 sea level high latitude we also infer that the resulting production rate ratio p21ne p10be of 21ne and 10be changes with depth below the earth s surface this ratio in turn may provide supplemental erosion rate information in geological settings of varying erosion surface covers and for long time scales when radionuclide data provide incomplete information in environments with very low erosion rates our calculations indicate noticeable differences in the production ratios p21ne p10be specifically for long time scales however calibrations are needed and may be carried out on a well documented quartz core

evidence for subduction related components in the subcontinental mantle from low 3he 4he and 40ar 36ar ratio in mantle xenoliths from far eastern russia abstract by applying both vacuum crushing and stepwise heating methods for the extraction of the noble gases we have discovered 3he 4he ratios much lower than the atmospheric ratio 0 3 ra ra is the atmospheric 3he 4he ratio of 1 4 10 6 and relatively low 40ar 36ar ratios spectroscopic and petrographic observations confirm that there are at least two compositionally distinct fluids in these xenoliths liquid co2 inclusions and melt inclusions with shrinkage bubbles based on the crushing experiments it is inferred that the inclusions of liquid co2 have a 3he 4he ratio similar to that of morb and the component with the low 3he 4he ratio is derived from the shrinkage bubbles in the melt inclusions for the present samples the 40ar 36ar ratios obtained by crushing were less than 1000 suggesting incorporation of atmospheric components in the source materials since low 40ar 36ar ratios were observed irrespective of the occurrence of the liquid co2 inclusions the atmospheric component exists in the melt inclusions ne and xe isotopes are also consistent with incorporation of atmospheric components since the far eastern russia area was located at a subduction zone in the jurassic early cretaceous period it is most likely that the melt inclusions displaying atmospheric noble gas characteristics together with low 3he 4he ratios have been derived from the jurassic cretaceous subducted slab although we cannot exclude the possibility that low 3he 4he ratios are due to the existence of minor u bearing minerals in the lithospheric continental mantle caused by metasomatism we have no petrographical evidence for such minerals in this area on the other hand 3he 4he ratios observed in the liquid co2 inclusions which are similar to the morb like value might reflect the general character of the upper mantle the far eastern russian mantle may therefore be a morb like source that has been partly infiltrated by subduction related fluids

a constant stress drop model for producing broadband synthetic seismograms comparison with the next generation attenuation relations broadband 0 1 20 hz synthetic seismograms for finite fault sources were produced for a model where stress drop is constant with seismic moment to see if they can match the magnitude dependence and distance decay of response spec tral amplitudes found in the next generation attenuation nga relations recently developed from strong motion data of crustal earthquakes in tectonically active re gions the broadband synthetics were constructed for earthquakes of m 5 5 6 5 and 7 5 by combining deterministic synthetics for plane layered models at low fre quencies with stochastic synthetics at high frequencies the stochastic portion used a source model where the brune stress drop of 100 bars is constant with seismic mo ment the deterministic synthetics were calculated using an average slip velocity and hence dynamic stress drop on the fault that is uniform with magnitude one novel aspect of this procedure is that the transition frequency between the deterministic and stochastic portions varied with magnitude so that the transition frequency is inversely related to the rise time of slip on the fault the spectral accelerations at 0 2 1 0 and 3 0 sec periods from the synthetics generally agreed with those from the set of nga relations for m 5 5 7 5 for distances of 2 100 km at distances of 100 200 km some of the nga relations for 0 2 sec spectral acceleration were substantially larger than the values of the synthetics for m 7 5 and m 6 5 earthquakes because these relations do not have a term accounting for q at 3 and 5 sec periods the synthetics for m 7 5 earth quakes generally had larger spectral accelerations than the nga relations although there was large scatter in the results from the synthetics the synthetics showed a sag in response spectra at close in distances for m 5 5 between 0 3 and 0 7 sec that is not predicted from the nga relations

a hybrid method for calculating near source broadband seismograms application to strong motion prediction abstract we present a hybrid method for computing broadband strong motion seismograms in the near field of large earthquakes we combine complete seismograms at low frequency with ray theory seismograms at high frequency to form a composite broadband seismogram that spans the entire frequency range of interest in our approach the amplitude spectra of the two sets of synthetic seismograms are reconciled at intermediate frequencies where their domain of validity overlaps we demonstrate the method with scenario earthquakes based on the spatial random field model for complex earthquake slip j geophys res 107 b11 2002 2308 the hybrid near source broadband seismograms are useful both for detailed source modeling and for incorporating source effects into probabilistic seismic hazard analysis

ground motion modeling of hayward fault scenario earthquakes part ii simulation of long period and broadband ground motions abstract we simulate long period t 1 0 2 0 s and broadband t 0 1 s ground motions for 39 scenario earthquakes m w 6 7 7 2 involving the hayward calaveras and rodgers creek faults for rupture on the hayward fault we consider the effects of creep on coseismic slip using two different approaches both of which reduce the ground motions compared with neglecting the influence of creep nevertheless the scenario earthquakes generate strong shaking throughout the san francisco bay area with about 50 of the urban area experiencing modified mercalli intensity vii or greater for the magnitude 7 0 scenario events long period simulations of the 2007 m w 4 18 oakland earthquake and the 2007 m w 5 45 alum rock earthquake show that the u s geological survey s bay area velocity model version 08 3 0 permits simulation of the amplitude and duration of shaking throughout the san francisco bay area for hayward fault earthquakes with the greatest accuracy in the santa clara valley san jose area the ground motions for the suite of scenarios exhibit a strong sensitivity to the rupture length or magnitude hypocenter or rupture directivity and slip distribution the ground motions display a much weaker sensitivity to the rise time and rupture speed peak velocities peak accelerations and spectral accelerations from the synthetic broadband ground motions are on average slightly higher than the next generation attenuation nga ground motion prediction equations we attribute much of this difference to the seismic velocity structure in the san francisco bay area and how the nga models account for basin amplification the nga relations may underpredict amplification in shallow sedimentary basins the simulations also suggest that the spudich and chiou 2008 directivity corrections to the nga relations could be improved by increasing the areal extent of rupture directivity with period

surface rupture and slip distribution of the 12 november 1999 duzce earthquake m 7 1 north anatolian fault bolu turkey the 12 november 1999 earthquake m 7 1 occurred on the duzce fault a splay of the north anatolian fault in the bolu basin approximately three months after the 17 august 1999 m 7 4 earthquake the surface rupture was 40 km long and the maximum right lateral offset was 500 5 cm averaging 300 cm the 9 km of the westernmost part of the rupture along the southern margin of the eften lake had a 350 cm maximum vertical displacement normal faulting some of which was already ruptured during the 17 august 1999 event with few tens of centimeters the surface rupture has a generally simple narrow deformation zone of 0 5 5 m however in some places it widens to 50 m transtensional and transpressional structures were observed within releasing and restraining step over areas respectively the larger dextral offsets on some streams indicate previous events the dextral slip measurements along the rupture reflect a symmetric distribution the eastern connection of this rupture zone with the main trace of north anatolian fault remains unclear because the bakacak and elmalik fault which are connecting faults had no surface rupture manuscript received 14 november 2000

an efficient method for computing green s functions for a layered half space at large epicentral distances nowadays with the dramatic increase in computational ability the dis crete wavenumber integration method dwim see e g bouchon and aki 1977 bouchon 1979 1981 has been one of the most favorable techniques of computing the synthetic seismograms for a layered half space because of its simplicity accuracy and fair efficiency for some cases particularly for the case of the near field however it becomes less efficient for the case of far field that is at large epicentral distances and the larger the epicentral distance is the less efficient dwim will be in this study we propose an efficient numerical wavenumber integration method the self adaptive filon s integration method safim to compute efficiently the dynamic green s functions for a layered half space at large epicentral distances this new integration technique is build upon the particular fifth order filon s integration scheme apsel 1979 apsel and luco 1983 and the principle of the self adaptive simpson inte gration technique by using numerical examples we demonstrate that safim is not only accurate but also very efficient for large epicentral distances according to our study we find that at a relatively short epicentral distance r 500 km the classical dwim is more efficient than safim at a medium range of epicentral distance 500 kmr 1200 km both methods have similar efficiency at large epicentral dis tance r 1200 km however safim is significantly more efficient than dwim and the larger the epicentral distance is the more efficient safim will be for in stance when r 2000 km safim only needs about 1 3 of the computation time of dwim therefore this new integration method is expected to be very useful in com puting synthetic seismograms at large epicentral distances

cosmic ray produced neon in antarctic rocks we studied three antarctic rocks and quartz separates thereof for their records of cosmic ray produced 21ne all three samples reveal an excess of 21ne and in two of them a cosmic ray origin is documented by the spallation ratios 22ne 21ne 3he is shown to be incompletely retained in quartz 10 previous studies have shown the suitability of quartz as a monitor for cosmic ray produced radionuclides 10be and 26al and therefore as a tracer for geological processes 26al 10be ratios allow the calculation of minimum exposure ages and maximum erosion rates and measured ratios 21ne 10be and 21ne 26al add significant information to exposure histories especially in the case of a complex exposure this information is necessary for an evaluation of erosion rates and to define geological processes such as uplift and variations in the antarctic ice cover

an isochron approach to 21ne cosmic ray exposure dating by activation with deuteron deuteron fusion neutrons abstract this paper describes an alternative approach to cosmogenic 21 ne 21 ne cos exposure dating that entails irradiating mg bearing samples in a deuteron deuteron d d neutron generator to produce 22 ne by the reaction 25 mg n 22 ne mg following irradiation and provided that the 22 ne mg 22 ne cos ratio is greater than 10 3 one can identify cosmogenic 21 ne using a 21 ne 20 ne vs 22 ne 20 ne isochron the method is analogous to identifying radiogenic 40 ar using a conventional 40 ar 36 ar vs 39 ar k 36 ar isochron with knowledge of the 21 ne production rate and the relationship between 22 ne mg and mg content determined by co irradiating a standard of known mg concentration the slope of the isochron 21 ne cos 22 ne mg can be translated into an exposure age in this way a 21 ne exposure age is calculated without making assumptions regarding the isotopic composition of the trapped or cosmogenic components this technique if proven to be viable will be applicable to minerals that contain a stoichiometric abundance of mg e g orthopyroxene clinopyroxene and olivine

cosmic ray produced neon and helium in the summit lavas of maui a 3he component attributed to cosmic ray induced spallation reactions 3hec in silicate minerals has recently been identified in lava flows on the summit of haleakala volcano on maui1 3 this3hec is observed in the helium extracted by fusion of olivine and pyroxene phenocrysts after first removing almost all of the mantle derived helium by vacuum crushing a procedure which releases the volatiles trapped in fluid inclusions within the phenocrysts cosmic ray produced 3he was found in the high altitude 3 000 m summit lavas which are 500 000 years old but was not observed in sub surface samples which were overlain by younger basalts2 or in a 200 yr old lava flow at sea level on maui1 2 we report here the identification of cosmic ray produced 21nec in addition to 3hec in gases extracted by fusion of olivines and clinopyroxenes after vacuum crushing the observed 3he 21ne c ratios and the ratio of 21nec in olivine to that in clinopyroxene are consistent with an in situ origin of 3hec and 21nec by cosmic ray spallation reactions this component could be important for interpreting helium isotopic data in terrestrial reservoirs geophysical applications could include determinations of erosion rates and exposure histories of terrestrial rocks

relative and absolute dating of land surfaces abstract the dating of land surfaces has long posed problems for geomorphologists relative methods stratigraphic geomorphic topographic are sound and convincing exhumed forms may complicate identification and relationships for both epigene and etch forms have been buried and exhumed but in tectonically undisturbed areas the higher surfaces are older than those preserved at lower levels also surfaces have an age range the relationship of surfaces with volcanic deposits old shorelines and genetically related sedimentary sequences provides sound ages and correlation with dated duricrusts and faults is also useful there are no temporal limits to relative dating for the methods are equally applicable to the dating say of proterozoic surfaces as of those of pleistocene age the disadvantage of such methods is that the necessary evidence is frequently either not preserved or not exposed the so called absolute physical numerical methods and especially those based on exposure age dating with in situ cosmogenic radionuclides are appealing because they produce direct numerical ages and appear to be widely applicable but there are severe temporal limitations and sampling problems complicate and may invalidate interpretation absolute age determinations must be consistent with the stratigraphic and geomorphologic settings the best results are obtained when physicists and earth scientists pool their knowledge and experience a background in local and regional geology is especially important

cosmogenic noble gas paleothermometry we present a theoretical basis for reconstructing paleotemperatures from the open system behavior of cosmogenic noble gases produced in minerals at earth s surface experimentally determined diffusion kinetics predicts diffusive loss of cosmogenic 3he and 21ne from common minerals like quartz and feldspars at ambient temperatures incomplete retention has also been observed empirically in field studies we show that the theory of simultaneous production and diffusion that applies to radiogenic noble gases in minerals the basis of thermochronology can also be applied to cosmogenic noble gases to reconstruct past surface temperatures on earth we use published diffusion kinetics and production rates for 3he in quartz and 21ne in orthoclase to demonstrate the resolving power of cosmogenic noble gas paleothermometry with respect to exposure duration temperature and diffusion domain size calculations indicate that when paired with a quantitatively retained cosmogenic nuclide such as 21ne or 10be observations of cosmogenic 3he in quartz can constrain temperatures during surface exposure in polar and high altitude environments likewise 21ne retention in feldspars is sensitive to temperatures at lower latitudes and elevations expanding the potential geographic applicability of this technique to most latitudes as an example we present paired measurements of 3he and 10be in quartz from a suite of antarctic sandstone erratics to test whether the abundances of cosmogenic 3he agree with what is predicted from first principles and laboratory determined diffusion kinetics we find that the amounts of cosmogenic 3he present in these samples are consistent with the known mean annual temperature mat for this region of antarctica between 25 and 30 c these results demonstrate the method s ability to record paleotemperatures through geologic time

three dimensional simulation of earthquakes on the los angeles fault system we have used a 3d finite difference method to simulate ground motion from elastodynamic propagating ruptures with constant slip on faults in the metropolitan area of los angeles california simulations are carried out for hypothetical m 6 75 earthquakes on the palos verdes and elysian park faults and for comparison an approximation to the 17 january 1994 m 6 7 northridge earthquake the dominant subsurface features of this area are the deep sedimentary los angeles basin and the smaller and shallower san fernando basin simulated ground motions are restricted to the frequency range 0 0 to 0 4 hz ground motion time histories show that in general sites associated with the largest particle velocities and cumulative kinetic energies are located 1 in the epicentral area 2 above the deepest parts of the basins and 3 near the steepest edges of the los angeles basin we find maximum particle velocities for the palos verdes elysian park and northridge simulations of 0 44 0 67 and 0 58 m sec respectively in each case both the directivity of the rupture and the lower impedance of the basins significantly amplify the ground motion although the gross radiation pattern from these ruptures is observable the 3d basin structure distorts the wave field and becomes a source for edge generated waves signal durations at some basin sites last beyond 90 sec due to love waves and refracted s waves that propagate into the sediments from the basin edges compared with the palos verdes event the durations are generally smaller for the elysian park earthquake due to a smaller amount of love waves generated at the basin edges a simple approximation to the northridge earthquake reproduces the overall spatial pattern of the long period particle velocities successfully predicts the timing of late arriving waves and matches the peak velocities with discrepancies generally less than a factor of 2 however for localized areas immediately north and south of the santa monica mountains the computed ground motion underpredicts the observed horizontal peak velocities but matches the vertical ones the pattern of simulated total cumulative kinetic energies is similar to that for the damage intensities observed near the epicenter of the northridge event while the northridge earthquake caused damage in the los angeles area the 3d simulations show that earthquakes with the same magnitude on the palos verdes or elysian park faults produce more severe ground shaking in the los angeles basin

strong ground motion estimation in the sea of marmara region turkey based on a scenario earthquake we perform a broadband frequency bedrock strong ground motion simulation in the marmara sea region turkey based on several fault rupture scenarios and a source asperity model the technique combines a deterministic simulation of seismic wave propagation at low frequencies with a semi stochastic procedure for the high frequencies to model the high frequencies we applied a frequency dependent radiation pattern model which efficiently removes the effective dependence of the pattern coefficient on the azimuth and take off angle as the frequency increases the earthquake scenarios considered consist of the rupture of the closest segments of the north anatolian fault system to the city of istanbul our scenario earthquakes involve the rupture of the entire north anatolian fault beneath the sea of marmara namely the combined rupture of the central marmara fault and north boundary fault segments we defined three fault rupture scenarios based on the location of the hypocenter selecting a preferred hypocentral location near a fault bend for each case we analysed the effect of location of the asperity within the central marmara fault on the subsequent ground motion as well as the influence of anelasticity on the highfrequency attenuation characteristics the fault and asperity parameters for each scenario were determined from empirical scalings and from results of kinematic and dynamic models of fault rupture we calculated the resulting time series and spectra for ground motion at istanbul and evaluated the sensitivity of the predictions to choice of model parameters the location of the hypocenter is thus shown to be a critical parameter for determining the worst scenario earthquake at istanbul we also found that anelasticity has a significant effect on the regional attenuation of peak ground accelerations our simulated ground motions result in large values of acceleration response spectra at long periods which could be critical for building damage at istanbul during an actual earthquake d 2004 elsevier b v all rights reserved

rupture process of the 1999 mw 7 1 duzce earthquake from joint analysis of spot gps insar strong motion and teleseismic data a supershear rupture with variable rupture velocity we analyze the rupture process of the 1999 m w 7 1 duzce earthquake using seismological remote sensing and geodetic data ground deformation measured from the subpixel cross correlation of satellite pour l observation de la terre spot images reveals a 55 km long fault trace and smooth surface slip distribution peaking at 3 5 4 m the westernmost segment overlaps for over 10 km with ruptures from the m w 7 4 izmit earthquake the 15 km long easternmost segment which cuts across mountainous topography had not been reported previously we determine a well constrained source model using a four segment fault geometry using constraints on surface fault slip and inverting global positioning system and interferometric synthetic aperture radar data along with strong motion records our results show that some variability of the rupture velocity and an eastward supershear velocity are required to fit the strong motion data the rise time up to 6 sec correlates with cumulative slip suggesting a sliding velocity of about 1 m sec the source model predicts teleseismic waveforms well although early by 2 sec this time shift is probably due to the weak beginning of the earthquake that is not observable at teleseismic distances strong motion records are relatively well predicted from a source model derived from the teleseismic data using the fault geometry derived from the satellite images this study demonstrates the benefit of using accurate fault geometries to determine finite fault source models

love wave propagation in a three dimensional sedimentary basin abstract a simplified three dimensional finite element method has been developed for simulation of love wave propagation in three dimensional sedimentary basins the eigenfunctions for the fundamental mode surface waves are employed as interpolation functions in the finite element scheme by reducing the number of degrees of freedom the method enables us to analyze wave propagation in an area of 2000 km 2 as large as the southern part of the kanto plain japan time histories of the near izu ohshima earthquake of 1990 are calculated and compared with observation calculated displacement snapshots show the effect of three dimensional topography on direction of love wave propagation the three dimensional simulation is also compared with a two dimensional one demonstrating amplitude increase and extended duration time histories and their spectra from the three dimensional model show better agreement with the observations than those from the two dimensional model

a three dimensional simulation of seismic waves in the santa clara valley california from a loma prieta aftershock abstract the finite difference method is used to propagate elastic waves through a 3 d model of the santa clara valley an alluvium filled basin that underlies the city of san jose california the model was based on depth to bedrock information from water wells in the area the simulation corresponded to a region 30 east west by 22 north south by 6 depth km and contained about 4 million grid points synthetic seismograms from the simulation are accurate at frequencies up to 1 hz motions from a magnitude 4 4 aftershock of the loma prieta earthquake were modeled snapshots of ground motion and synthetic seismograms from the simulation are presented the simulation illustrates s to surface wave conversion at the edges of the basin and the large amplitude and long duration of ground motion in the basin compared to the surrounding rock love waves produced at the edge of the basin are the largest arrivals in the transverse synthetics because of the slow group velocity of the love waves sites near the center of the basin have longer durations of significant motions than basin sites near the valley edges sites near the center of the basin also show larger peak amplitudes on the transverse component array analysis of the synthetic seismograms indicates that love waves tend to propagate parallel to the eastern and western edges of the valley rayleigh waves are produced along the southern margin of the basin from incident s waves large radial motions occur where a rayleigh wave impinges on the northeast margin of the valley some rayleigh waves travel westward across the basin after being scattered from the eastern edge of the valley synthetic seismograms from the simulation have similar peak amplitudes as seismograms recorded by the sunnyvale dense array for this aftershock although the duration of the tranverse component is not matched by the synthetic seismogram using this basin model the simulation indicates that the love waves observed on the actual seismograms were produced by conversion of incident s waves at the southern margin of the santa clara valley 2 d simulations show how the s to love wave conversion is affected by the angle of incidence of the s wave and the sharpness of the velocity transition between the alluvium and bedrock as more accurate basin models are developed 3 d simulations should become valuable for predicting ground motions in sedimentary basins for future large earthquakes

stochastic strong ground motion simulation of the 12 november 1999 duzce turkey earthquake using a dynamic corner frequency approach on 12 november 1999 only three months after the 17 august 1999 kocaeli earthquake mw 7 4 an earthquake of mw 7 1 occurred immediately to the east of the kocaeli rupture in northwestern turkey resulting in extensive structural damage in the city of duzce and its surrounding area it was reported to be a right lateral strike slip event on the previously unbroken segment of the north anatolian fault zone with a north dipping fault plane this paper presents stochastic finite fault simulation of near field ground motions from this earthquake at selected near fault stations based on a dynamic corner frequency approach using the computer program exsim motazedian and atkinson 2005 the method requires region specific source path and site characterizations as input model parameters the source mech anism of the 1999 duzce event and regional path effects are well constrained from previous studies of the earthquake the local site effects at the selected stations are studied as a combination of the kappa operator and frequency dependent soil ampli fication the model parameters are validated against recordings and a stress drop value of 100 bars is estimated for the 1999 duzce earthquake the validated model is then used to compute synthetic records around the fault distribution of peak ground motion parameters is observed to be consistent with the building damage dis tribution in the near fault region most affected by the seismic shaking the attenuation of synthetic ground motion parameters is compared with recent ground motion pre diction equations proposed for the region by gulkan and kalkan 2002 ulusay et al 2004 and akkar and bommer 2007 as well as two next generation attenuation models by boore and atkinson 2007 and campbell and bozorgnia 2007 despite discrepancies at several stations stochastic finite fault modeling based on a dynamic corner frequency approach confirms to be a practical tool to reproduce the ground motions of large earthquakes

characterization of aftershock fault plane orientations of the 1999 izmit turkey earthquake using high resolution aftershock locations 1 joint inversion for hypocentral parameters and the velocity field is nowadays a state of the art tool to obtain high resolution images of seismically active regions in this study we focus on the location accuracy of aftershocks of the 1999 mw 7 4 izmit nw turkey earthquake we obtained a new velocity model for the region and depicted its improvement on absolute locations in terms of uncertainty and misfit two well developed aftershock clusters located in the akyazi area and karadere duzce region were analyzed in detail based on a waveform cross correlation approach that allowed improving the location accuracy by a factor of 6 relocation results reveal that hypocenters form narrow planes of activity that can be correlated with focal mechanisms of the larger aftershocks as well as nearby clouds of activity with no internal structure down to the resolved scale of 300 m

assessment of simulated ground motions in earthquake engineering practice a case study for duzce turkey simulated ground motions can be used in structural and earthquake engineering practice as an alternative to or to augment the real ground motion data sets common engineering applications of simulated motions are linear and nonlinear time history analyses of building structures where full acceleration records are necessary before using simulated ground motions in such applications it is important to assess those in terms of their frequency and amplitude content as well as their match with the corresponding real records in this study a framework is outlined for assessment of simulated ground motions in terms of their use in structural engineering misfit criteria are determined for both ground motion parameters and structural response by comparing the simulated values against the corresponding real values for this purpose as a case study the 12 november 1999 duzce earthquake is simulated using stochastic finite fault methodology simulated records are employed for time history analyses of frame models of typical residential buildings next the relationships between ground motion misfits and structural response misfits are studied results show that the seismological misfits around the fundamental period of selected buildings determine the accuracy of the simulated responses in terms of their agreement with the observed responses

rockfall activity from an alpine cliff during thawing periods abstract rockfall activity during thawing periods was investigated by collecting rockfall debris fallen on the snow covered talus slope in a cirque in the japanese alps near surface rock temperature was also monitored on the cirque wall maximum rockfall activity occurs on average about 10 days after the meltout of the cirque wall the intensive activity is rarely associated with precipitation events or diurnal frost cycles on the rockface a thermal conduction model suggests that rockfalls at this site occur most frequently when the seasonal thawing front penetrates to a depth of about 1 m in the bedrock while the freeze thaw penetration controls the maximum dimensions of detachable rock mass joint spacing on the rockface affects the size distribution of rockfall debris boulder falls resulting from seasonal frost weathering are considered to be the most important process responsible for the contemporary modification of the cirque wall the rockfall volume during a thawing period is usually 1 3 m3 which is equivalent to the rate of cirque wall retreat of the order of 0 01 mm year 1 however big boulder falls that occur once per decade can increase the retreat rate significantly

modeling finite fault radiation from the ωn spectrum the high frequency seismic field near the epicenter of a large earth quake is modeled by subdividing the fault plane into subelements and summing their contributions at the observation point each element is treated as a point source with an o92 spectral shape where co is the angular frequency ground motion contributions from the subsources are calculated using a stochastic model attenuation is based on simple geometric spreading in a whole space coupled with regional anelastic atten uation q operator the form of the co n spectrum with natural n follows from point shear dislocation theory with an appropriately chosen slip time function the seismic moment and comer frequency are the two parameters defining the point source spectrum and must be linked to the subfanlt size to make the method complete two coefficients aa and k provide this link assigning a moment to a subfault of specified size introduces the stress parameter ao the relationship between comer frequency dislocation growth rate and fault size is established through the coefficient k which is inherently nonunique these two parameters control the number of subsources and the ampli tudes of high frequency radiation respectively derivation of the model from shear dislocation theory reveals the unavoidable uncertainty in assigning ogn spectrum to faults with finite size this uncertainty can only be reduced through empirical vali dation the method is verified by simulating data recorded on rock sites near epicenters of the m8 0 1985 michoacan mexico the m8 0 1985 valparaiso chile and the m5 8 1988 saguenay qurbec earthquakes each of these events is among the largest for which strong motion records are available in their respective tectonic environ ments the simulations for the first two earthquakes are compared to the more de tailed modeling of somerville et al 1991 which employs an empirical source function and represents the effects of crustal structure using the theoretical impulse response both methods predict the observations accurately on average the precision of the methods is also approximately equal the predicted acceleration amplitudes in our model are generally within 15 of observations an unexpected result of this study is that a single value of a parameter k provides a good fit to the data at high frequencies for all three earthquakes despite their different tectonic environments this suggests a simplicity in the modeling of source processes that was unanticipated

cosmogenic neon and helium at reunion measurement of erosion rate abstract we report analyses of both helium and neon for olivine separates from a drill core at an altitude of 2330 m in oceanite at piton de la fournaise volcano we show for the first time that cosmogenic 21 ne like cosmogenic 3 he decreases exponentially with core depth we obtain an attenuation length of 165 6 g cm 2 1 for cosmogenic 21 ne identical to the value found previously for cosmogenic 3 he alone 1 for each depth in the core the measured amount of cosmogenic 21 ne is about 13 lower than predicted based on the high precision k ar age of 65 200 2000 yrs 1 2 and this result is attributed to erosion assuming a constant erosion rate we derive a value of 3 5 1 7 mm yr 1 from the 21 ne data the same order of magnitude as the value obtained from cosmogenic 3 he at haleakala 1 3 this work highlights the important potential of both cosmogenic helium and neon for measuring in situ exposure ages and erosion rates

estimating rates of denudation using cosmogenic isotope abundances in sediment we propose as a testable hypothesis a basin scale approach for interpreting the abundance of in situ produced cosmogenic isotopes an approach which considers explicitly both the isotope and sediment flux through a drainage basin unlike most existing models which are appropriate for evaluating in situ produced cosmogenic isotope abundance at discrete points on earth s surface our model is designed for interpreting isotope abundance in sediment because sediment is a mixture of materials in favourable cases derived from throughout a drainage basin we suggest that measured isotope abundances may reflect spatially averaged rates of erosion we investigate the assumptions and behaviour of our model and conclude that it could provide geomorphologists with a relatively simple means by which to constrain the rate of landscape evolution if a basin is in isotopic steady state and if sampled sediments are well mixed

3 d wave propagation in the los angeles basin for the whittier narrows earthquake abstract elastic wave propagation within and around the los angeles basin during the whittier narrows earthquake in 1988 is simulated with a 3 d finite difference method the model consists mainly of a sedimentary layer over the basement but lateral variations inside the sedimentary basin is also included to approximate observed variations in surface shear velocity the minimum shear velocity is 1 km sec on the surface and fairly reliable results are obtained up to 0 75 hz the total simulation lasts 26 sec our simulation can reproduce the general amplification pattern small east of the epicenter and large in the l a basin and the san fernando valley due to thick sediments of low velocity in these areas surface waves are generated by the primary s wave and trapped inside the basins in the southern part of the l a basin a distinct later phase delayed by 5 to 6 sec relative to the primary s wave is produced in our simulation which matches some strong motion records

the rupture process during the 1999 duzce turkey earthquake from joint inversion of teleseismic and strong motion data abstract teleseismic and strong motion data are inverted to determine the rupture process during the november 1999 duzce earthquake in nw turkey the fault geometry rise time and rupture velocity are determined from the aftershock distribution and preliminary inversions of the teleseismic data joint inversion of the teleseismic and strong motion data is then carried out for the slip distribution we obtain the strike 264 dip 64 rake 172 seismic moment 5 0 1019 n m mw 7 1 and average stress drop 7 mpa this earthquake was characterized by bilateral fault rupture and asymmetric slip distribution two asperities areas of large slip are identified the eastern one being 1 5 times larger than the western one the derived slip distribution is consistent with the aftershock distribution surface rupture and damage the point of rupture initiation in this duzce earthquake coincided with the eastern tip of the aftershock distribution of the august 1999 izmit earthquake

the rate of bedrock weathering by frost action field measurements and a predictive model shattering rate surface temperature moisture content and the physical and strength properties of bedrock were measured in four rockwall sites of the japanese alps five year observations revealed that the bedrock shattering rate was usually much higher in the freeze thaw period from october to next may than in the frost free period from june to september this indicates that frost action is the most important shattering process although unusual heavy rainstorms in summer are also responsible for the shattering a combination of some empirical relationships derived from recent laboratory experiments leads to a predictive model of the frost shattering rate this model shows that the annual shattering rate is dependent on the annual freeze thaw frequency on the rock surface and the degree of saturation and tensile strength of the rock masses the coefficients involved in the model were determined using the field data

mass spectrometric identification of cosmic ray produced neon in terrestrial rocks with multiple neon components studies of cosmic ray produced nuclides in terrestrial rocks are expected to provide important geomorphological and glaciological information such as surface exposure ages erosion rates and extent of glacial cover in the case of the stable nuclide21ne the cosmic ray produced component may represent but one of several components and a component resolution based on three isotope correlations is essential we developed analytical techniques which permit accurate corrections for all interfering ions we show for our modified nier source that corrections for doubly charged species based on constant charge state ratios are not satisfactory the improved techniques permit isotopic studies of 106 atoms of21ne the spallation ratio 22ne 21ne c from si was calibrated using a quartz separate from an allan hills sandstone and yields a value of1 243 0 022 this ratio is expected to be essentially constant for terrestrial quartz samples and should be useful in component resolutions the stepwise release of ne at increasing temperatures shows that cosmic ray produced ne is released from quartz at rather low temperatures this permits an estimate of the activation energy for ne diffusion in quartz 90 10 kj mol

a local ground motion predictive model for turkey and its comparison with other regional and global ground motion models we examined the differences between the ground motion estimations of local and global prediction equations and explored some seismological parameters that may explain these differences to achieve this objective we first derived a set of ground motion prediction equations gmpes for estimating peak horizontal accel eration velocity and pseudospectral acceleration using the recently compiled turkish ground motion database the new gmpes are comparable with the recent global gmpes in terms of model sophistication and they are based on a well studied national dataset using global gmpes from the next generation attenuation of ground motions project power et al 2008 and the pan european akkar and bommer 2010 model we observed that the discrepancy between local and global gmpes is more prominent at small magnitudes provided that the gmpes possess similar mag nitude limits our more detailed comparisons with the pan european akkar and bom mer 2010 predictive model as well as with the estimations from a combined italian and turkish accelerometric dataset indicate that depth can be of importance for delineating the differences between local and global gmpes