fault interactions in the sea of marmara pull apart north anatolian fault earthquake clustering and propagating earthquake sequences summary knowledge on large earthquakes m 7 0 geology and fault kinematics is used to analyse conditions that favour isolated seismicity clustered earthquakes or propagating sequences along the north anatolian fault naf and the sea of marmara pull apart the overall naf marmara fault system is one of the most appropriate on earth to document fault interactions because reliable information covers almost completely two seismic cycles the past 500 yr coulomb stress analysis is used to characterize loading evolution in well identified fault segments including secular loading from below and lateral loading imposed by the occurrence of previous earthquakes earthquakes along the naf tend to occur where previous events have increased the stress but significant isolated events in the sea of marmara region 1894 1912 have occurred suggesting the secular loading has been the determining factor present day loading appears to be particularly high along the 70 km long segment located in the central marmara sea southwest of istanbul for the 18th century m 7 0 earthquake clusters we construct scenarios consistent with the tectonic and historical data we find that scenarios consistent with slip deficit and secular loading distributions from below clearly involve a sequence that propagates westward through the sea of marmara despite the structural complexity however the inference of a propagating sequence implies that each event has occurred in a segment previously stressed by lateral coulomb stress interactions the most likely scenarios for the propagating sequence are also consistent with coulomb stress interactions between faults with significant normal slip across the cinarcik basin propagating earthquake sequences do not occur every seismic cycle along the naf the loading has to be in a particular state of stress close to failure and uniform all along the fault segments to experience propagating earthquake sequences non uniform stress relief during the 18th century sequence explains the occurrence of isolated events in marmara in 1894 and 1912 as a consequence the wellknown 20th century sequence along the naf has not propagated as a sequence across the sea of marmara the most linear part of the naf across northern turkey behaves as a single fault segment accumulating stress during hundreds of years and rupturing entirely during very short periods the marmara pull apart fault system behaves as a major geometric complexity stopping or delaying the progression of earthquake clustering and propagating sequences fault zones interact with each other at a very large scale

geometric sound propagation through an inhomogeneous and moving ocean scattering by small scale internal wave currents ray equations appropriate for ocean acoustic propagation through an inhomogeneous and moving ocean are put forth with applications to sound scattering by internal waves the result reveals the important role played by range dependent horizontal current shear the garrett munk internal wave model and observations of upper ocean shear and sound speed fluctuations suggest that inertial frequency upper ocean shear may play a comparable role to internal wave induced sound speed fluctuations as a source of upper ocean acoustic scattering

dissociation of oceanic methane hydrate as a cause of the carbon isotope excursion at the end of the paleocene isotopic records across the latest paleocene thermal maximum lptm indicate that bottom water temperature increased by more than 4 c during a brief time interval 104 years of the latest paleocene 55 6 ma there also was a coeval 2 to 3 excursion in the 13c of the ocean atmosphere inorganic carbon reservoir given the large mass of this reservoir a rapid 13c shift of this magnitude is difficult to explain within the context of conventional hypotheses for changing the mean carbon isotope composition of the ocean and atmosphere however a direct consequence of warming bottom water temperature from 11 to 15 c over 104 years would be a significant change in sediment thermal gradients and dissociation of oceanic ch4 hydrate at locations with intermediate water depths in terms of the present day oceanic ch4 hydrate reservoir thermal dissociation of oceanic ch4 hydrate during the lptm could have released greater than 1 1 to 2 1 1018 g of carbon with a 13c of approximately 60 the release and subsequent oxidation of this amount of carbon is sufficient to explain a 2 to 3 excursion in 13c across the lptm fate of ch4 in oceanic hydrates must be considered in developing models of the climatic and paleoceanographic regimes that operated during the lptm

observations and models of inertial waves in the deep ocean the structure of the inertial peak in deep ocean kinetic energy spectra is studied here records were obtained from polymode arrays deployed in the western north atlantic ocean 40 w to 70 w 15 n to 42 n the results are interpreted both in terms of local sources and of turning point effects on internal waves generated at lower latitudes in most of the data there is a prominent inertial peak slightly above f however the peak height above the background continuum varies with depth and geographical environment three classes of environment and their corresponding spectra emerge from peak height variations class 1 is the 1500 m level near the mid atlantic ridge with the greatest peak height of 18 db class 2 includes a the upper ocean depth less than 2000 m b the deep ocean depth greater than 2000 m over rough topography and c the deep ocean underneath the gulf stream with intermediate peak height of 11 5 db class 3 is the deep ocean over smooth topography with the lowest peak height of 7 5 db near f the horizontal coherence scale is 0 60 km at depths from 200 m to 600 m and the vertical coherence scale is 0 200 m in the lower part of the main thermocline and 0 1000 m in the deep water the phase difference suggests a downward energy propagation in the lower thermocline and standing waves in the deep water a one turning point model is developed to describe inertial waves at mid latitudes based on the assumption that inertial waves are randomly generated at lower latitudes global generation where their frequency wave number spectrum is given by the model of garrett and munk 1972 1975 using the globally valid wave functions obtained by munk and phillips 1968 various frequency spectra near f are calculated numerically the model yields a prominent inertial peak of 7 db in the horizontal velocity spectrum but no peaks in the temperature spectrum the model is latitudinally dependent the frequency shift and bandwidth of the inertial peak decrease with latitude energy level near f is minimum at about 30 and higher at low and high latitudes the observations of class 3 can be well described by the model a low zonal wave number cutoff is required to produce the observed frequency shift of the inertial peak the differences between the global generation model and the observations of class 1 and class 2 are interpreted as the effects of local sources a locally forced model is developed based on the latitudinal modal decomposition of a localized source function asymptotic eigensolutions of laplace s tidal equation are therefore derived and used as a set of expansion functions the forcing is through a vertical velocity field specified at the top or bottom boundaries of the ocean for white noise forcing the horizontal velocity spectrum of the response has an inertial peak which diminishes in the far field with the forcing located at either the surface or the bottom several properties of the class 2 observations can be described qualitatively by a combination of the global and local models the reflection of inertial waves from a turbulent benthic boundary layer is studied by a slab model of given depth frictional effects are confined to the boundary layer and modeled by a quadratic drag law for given incident waves reflection coefficients are found to be greater than 0 9 for the long waves which contain most of the energy this result suggests that energy containing inertial waves can propagate over great distance as is required by the validity of the model of global generation

marine methane cycle simulations for the period of early global warming geochemical environments fates and effects are modeled for methane released into seawater by the decomposition of climate sensitive clathrates a contemporary global background cycle is first constructed within the framework of the parallel ocean program input from organics in the upper thermocline is related to oxygen levels and microbial consumption is parameterized from available rate measurements seepage into bottom layers is then superimposed representing typical seabed fluid flow the resulting ch sub 4 distribution is validated against surface saturation ratios vertical sections and slope plume studies injections of clathrate derived methane are explored by distributing a small number of point sources around the arctic continental shelf where stocks are extensive and susceptible to instability during the first few decades of global warming isolated bottom cells are assigned dissolved gas fluxes from porous media simulation given the present bulk removal pattern methane does not penetrate far from emission sites accumulated effects however spread to the regional scale following the modeled current system both hypoxification and acidification are documented sensitivity studies illustrate a potential for material restrictions to broaden the perturbations since methanotrophic consumers require nutrients and trace metals when such factors are considered methane buildup within the arctic basin is enhanced however freshened polar surface waters act as a barrier to atmospheric transfer diverting products into the deep return flow uncertainties in the logic and calculations are enumerated including those inherent in high latitude clathrate abundance buoyant effluent rise through the column representation of the general circulation and bacterial growth kinetics

redistribution of energy available for ocean mixing by long range propagation of internal waves ocean mixing which affects pollutant dispersal marine productivity and global climate1 largely results from the breaking of internal gravity waves disturbances propagating along the ocean s internal stratification a global map of internal wave dissipation would be useful in improving climate models but would require knowledge of the sources of internal gravity waves and their propagation towards this goal i present here computations of horizontal internal wave propagation from 60 historical moorings and relate them to the source terms of internal waves as computed previously2 3 analysis of the two most energetic frequency ranges near inertial frequencies and semidiurnal tidal frequencies reveals that the fluxes in both frequency bands are of the order of 1 kw m 1 that is 15 50 of the energy input and are directed away from their respective source regions however the energy flux due to near inertial waves is stronger in winter whereas the tidal fluxes are uniform throughout the year both varieties of internal waves can thus significantly affect the space time distribution of energy available for global mixing

faulting associated with historical and recent earthquakes in the eastern mediterranean region summary this paper summarizes evidence for surface faulting in historical and recent earthquakes in the eastern mediterranean region and in the middle east such information is particularly important for studies of active tectonics and for palaeoseismology we have found 78 cases of faulting pre 1900 and 72 post 1900 some of which show that faults that have apparently been inactive this century had already ruptured before 1900 for some cases faulting could not have been predicted from 20th century activity and in others it could have been expected but has not been observed during the instrumental period the data are suycient to allow the derivation of relationships between magnitude and rupture length

sharp near equatorial transitions in inertial motions and deep ocean step formation 1 the near equatorial region is importantly different from other ocean areas it acts as a barrier for large scale meridional circulation because the strongest currents are directed east west and it shows weak interior mixing despite large internal wave shear all seems related to a change in importance of the vertical inertial component of the earth s rotation as rotational effects dominate large scale ocean motions through a geostrophic balance they become negligible at the equator here deep ocean observational evidence is presented of hitherto neglected rotational effects it is demonstrated that when the equator is approached near inertial internal wave motions very suddenly rather than smoothly change polarization from near circular to near rectilinear within half a degree across latitudes 1 5 0 5 at the same latitudes sudden transitions are observed of large scale kinetic energy and small scale density stratification variations understanding the above requires a non traditional approach in which the horizontal component of earth s rotation is considered

observations of internal wave reflection off sloping bottoms current and temperature spectra exhibit intensification and polarization near sloping bottoms over a band of frequencies centered at the local internal wave critical frequency examples are drawn from a variety of island seamount and continental slope observations waves propagating down from mid depth change energy density wave number and azimuth when they reflect off the bottom providing a natural perturbation to the deep ocean interior internal wave spectrum deviations from linear theory are interpreted as evidence for dissipation through subsequent shear instability and or nonlinear interaction topographic features appear likely to be energy sinks for internal wave energy

rising arctic ocean temperatures cause gas hydrate destabilization and ocean acidification vast amounts of methane hydrates are potentially stored in sediments along the continental margins owing their stability to low temperature high pressure conditions global warming could destabilize these hydrates and cause a release of methane ch 4 into the water column and possibly the atmosphere since the arctic has and will be warmed considerably arctic bottom water temperatures and their future evolution projected by a climate model were analyzed the resulting warming is spatially inhomogeneous with the strongest impact on shallow regions affected by atlantic inflow within the next 100 years the warming affects 25 of shallow and mid depth regions containing methane hydrates release of methane from melting hydrates in these areas could enhance ocean acidification and oxygen depletion in the water column the impact of methane release on global warming however would not be significant within the considered time span

a 2000 year long paleoseismologic record of earthquakes along the central north anatolian fault from trenches at alayurt turkey paleoseismologic data from trenches excavated across the central part of the north anatolian fault at alayurt turkey reveal evidence for at least four and possibly five surface ruptures during the past 2000 years as well as one much older event these surface ruptures as recognized on the basis of upward fault terminations and colluvial gravel layers include 1 the historic 1943 m w 7 7 tosya earthquake 2 an older event that is not well dated but which we interpret as the great 1668 earthquake which historical accounts suggest ruptured this part of the fault 3 a late eighth to early thirteenth century surface rupture 4 a surface rupture that occurred between the first and third centuries a d possibly the historic a d 236 event 5 a possible surface rupture that occurred between the late fourth and early eleventh centuries a d and 6 a much older event that occurred sometime between 4600 and 3550 b c our documentation of a late eighth to early thirteenth century surface rupture at alayurt is particularly important because when taken in context with available historical and paleoseismologic data it suggests the occurrence of a brief interval during which large earthquakes ruptured most of the north anatolian fault this interval resembles two other short lived clusters of activity in the sixteenth to eighteenth and twentieth centuries these brief intervals of activity are separated by much longer periods of relative quiescence that range from 250 years to 800 years if there was not a late fourth to early eleventh century event or 600 years if there was a late fourth to early eleventh century event the factor of 2 3 variation in inter event times suggests quasiperiodic earthquake occurrence which we attribute to the structural simplicity and relative isolation of the central north anatolian fault from other earthquake producing faults

integration of paleoseismic data from multiple sites to develop an objective earthquake chronology application to the weber segment of the wasatch fault zone utah we present a method to evaluate and integrate paleoseismic data from multiple sites into a single objective measure of earthquake timing and recurrence on discrete segments of active faults we apply this method to the weber segment ws of the wasatch fault zone using data from four fault trench studies completed between 1981 and 2009 after systematically reevaluating the stratigraphic and chro nologic data from each trench site we constructed time stratigraphic oxcal models that yield site probability density functions pdfs of the times of individual earth quakes we next qualitatively correlated the site pdfs into a segment wide earthquake chronology which is supported by overlapping site pdfs large per event displace ments and prominent segment boundaries for each segment wide earthquake we computed the product of the site pdf probabilities in common time bins which emphasizes the overlap in the site earthquake times and gives more weight to the narrowest best defined pdfs the product method yields smaller earthquake timing uncertainties compared to taking the mean of the site pdfs but is best suited to earth quakes constrained by broad overlapping site pdfs we calculated segment wide earthquake recurrence intervals and uncertainties using a monte carlo model five surface faulting earthquakes occurred on the ws at about 5 9 4 5 3 1 1 1 and 0 6 ka with the exception of the 1 1 ka event we used the product method to define the earthquake times the revised ws chronology yields a mean recurrence interval of 1 3 kyr 0 7 1 9 kyr estimated two sigma 2 range based on interevent recurrence these data help clarify the paleoearthquake history of the ws including the important question of the timing and rupture extent of the most recent earthquake and are essential to the improvement of earthquake probability assessments for the wasatch front region

morphology displacement and slip rates along the north anatolian fault turkey 1 geological and geomorphological offsets at different scales are used to constrain the localization of deformation total displacement and slip rates over various timescales along the central and eastern north anatolian fault naf in turkey the naf total displacement is reevaluated using large rivers valleys 80 15 km and structural markers pontide suture 85 25 km tosya vezirkopru basins 80 10 km these suggest a neogene slip rate of 6 5 mm yr over 13 myr the river network morphology shows offsets at a range of scales 20 m to 14 km across the main fault trace and is also used to estimate the degree to which deformation is localized at a smaller scale the morphology associated with small rivers is offset by 200 m along the naf the age of these features can be correlated with the holocene deglaciation and a slip rate of 18 3 5 mm yr is determined this is consistent with a rate of 18 5 mm yr deduced independently from the 14c dating of stream terrace offsets over the short term gps data gives a similar rate of 22 3 mm yr all our results tend to show that most of the deformation between the anatolian and eurasian lithospheric plates has been accommodated along or very close to the active trace of the naf the difference between the neogene and the holocene slip rate may be due to the recent establishment of the current plate geometry after the creation of the naf

a relict paleoseismic record of seven earthquakes between 2000 b c and 600 a d on the central north anatolian fault at elmacik near osmancik turkey deformation along the northern edge of the westward moving anatolian plate is concentrated along the north anatolian fault this northward arching fault extends from the karliova triple junction in the east 1500 km into the aegean sea in the west a sequence of twentieth century earthquakes ruptured the fault displaying a spatiotemporal pattern consistent with a stress triggering mechanism in 1943 the m w 7 6 tosya earthquake ruptured a 280 km long segment near the center of the fault four paleoseismic investigations have previously investigated this segment and the present study was conducted near its center in an 180 km long gap between existing studies a paleoseismic trench revealed a sequence of eight sediment packages abutting a highly developed shear zone each of the packages consists of a fine grained layer overlying a coarse grained layer based on correlation between the age of the base of the coarse grained layers and existing earthquake records we infer that the coarse grained layers were deposited in response to earthquakes because of increased erosion on an adjacent steep slope the most recent event horizon may correlate to the historical 529 a d earthquake timing of six older earthquakes is constrained to 2s 23 b c 103 a d 609 185 b c 971 814 b c 1227 968 b c 2050 1777 b c and 2556 2235 b c which correspond to a summed interevent time of 97 912 yr 2s the earthquake record is relict because the local stream network was incised ca 1000 a d isolating the trench site from its sediment source a stream near the trench was subsequently offset by 23 5 1 5 m yielding a right lateral slip rate of 21 4 25 6 mm yr and suggesting that the 1943 rupture caused an uncharacteristically small offset

a blast of gas in the latest paleocene simulating first order effects of massive dissociation of oceanic methane hydrate carbonate and organic matter deposited during the latest paleocene thermal maximum is characterized by a remarkable 2 5 excursion in delta 13c that occurred over approximately 10 4 yr and returned to near initial values in an exponential pattern over approximately 2 x 10 5 yr it has been hypothesized that this excursion signifies transfer of 1 4 to 2 8 x 10 18 g of ch4 from oceanic hydrates to the combined ocean atmosphere inorganic carbon reservoir a scenario with 1 12 x 10 18 g of ch4 is numerically simulated here within the framework of the present day global carbon cycle to test the plausibility of the hypothesis we find that 1 the delta 13c of the deep ocean shallow ocean and atmosphere decreases by 2 3 over 10 4 yr and returns to initial values in an exponential pattern over approximately 2 x 10 5 yr 2 the depth of the lysocline shoals by up to 400 m over 10 4 yr and this rise is most pronounced in one ocean region and 3 global surface temperature increases by approximately 2 degrees c over 10 4 yr and returns to initial values over approximately 2 x 10 6 yr the first effect is quantitatively consistent with the geologic record the latter two effects are qualitatively consistent with observations thus significant ch4 release from oceanic hydrates is a plausible explanation for observed carbon cycle perturbations during the thermal maximum this conclusion is of broad interest because the flux of ch4 invoked during the maximum is of similar magnitude to that released to the atmosphere from present day anthropogenic ch4 sources

observations of near inertial surface currents off oregon decorrelation time and length scales 1 high resolution km in space and hourly in time surface currents observed by an array of high frequency radars off oregon are analyzed to quantify the decorrelation time and length scales of their near inertial motions the near inertial surface currents are dominantly clockwise with amplitudes of 9 12 cm s 1 however they appear asymmetric and elliptical as a result of counterclockwise inertial motions with magnitudes in a range of 2 5 cm s 1 the decorrelation time and length scales are computed from the decay slope of the near inertial peak and the spatial coherence in the near inertial frequency band respectively decorrelation time scales of clockwise near inertial motions increase from 2 days nearshore within 30 km from the coast to 6 days offshore and their length scales increase from 30 to 90 km seaward possibly due to coastal inhibition the local spatial coherence has an exponentially decaying structure for both clockwise and counterclockwise rotations and their phases propagate northwestward offshore for clockwise and northeastward onshore for counterclockwise rotations

a 3000 year record of ground rupturing earthquakes along the central north anatolian fault near lake ladik turkey the north anatolian fault naf is a similar to 1500 km long arcuate dextral strike slip fault zone in northern turkey that extends from the karliova triple junction to the aegean sea east of bolu the fault zone exhibits evidence of a sequence of large m w 7 earthquakes that occurred during the twentieth century that displayed a migrating earthquake sequence from east to west prolonged human occupation in this region provides an extensive but not exhaustive historical record of large earthquakes prior to the twentieth century that covers much of the last 2000 yr in this study we extend our knowledge of rupture events in the region by evaluating the stratigraphy and chronology of sediments exposed in a paleoseismic trench across a splay of the naf at destek similar to 6 5 km east of lake ladik 40 868 degrees n 36 121 degrees e the trenched fault strand forms an uphill facing scarp and associated sediment trap below a small catchment area the trench exposed a narrow fault zone that has juxtaposed a sequence of weakly defined paleosols interbedded with colluvium against highly fractured bedrock we mapped magnetic susceptibility variations on the trench walls and found evidence for multiple visually unrecognized colluvial wedges this technique was also used to constrain a predominantly dip slip style of displacement on this fault splay sediments exposed in the trench were dated using both charcoal and terrestrial gastropod shells to constrain the timing of the earthquake events while the gastropod shells consistently yielded 14 c ages that were too old by similar to 900 yr we obtained highly reliable 14 c ages from the charcoal by dating multiple components of the sample material our radiocarbon chronology constrains the timing of seven large earthquakes over the past 3000 yr prior to the 1943 tosya earthquake including event ages of 2 sigma error a d 1437 1788 a d 1034 1321 a d 549 719 a d 17 585 1 3 events 35 b c a d 28 700 392 b c 912 596 b c our results indicate an average interevent time of 385 166 degrees yr 1 sigma

global decline in ocean ventilation oxygenation and productivity during the paleocene eocene thermal maximum implications for the benthic extinction the prominent global warming event at the paleocene eocene boundary 55 ma referred to as the paleocene eocene thermal maximum petm was characterized by rapid temperature increase and changes in the global carbon cycle in

the mechanical interaction between the propagating north anatolian fault and the back arc extension in the aegean we use fracture mechanics concepts to analyse the large scale deformation of anatolia and the aegean our purpose is to characterize the process of propagation of the north anatolian fault naf our approach incorporates long term geological constraints in dislocation modelling of present day gps velocities that allows for internal deformation in regions between major structures unravelling the superposition of two deformation fields now interacting in the aegean propagating naf and back arc extension permits us to characterise the large scale damage zone at the western end of the naf and to determine slip rates for the main structures the contemporary slip rate profile of the naf shows that it apparently behaves like a transform fault for 75 of its length the process zone corresponds to a rapid southwestward tapering of the naf slip rate modelling slip rate distributions for the naf under stress free conditions shows that the development of the process zone depends on the boundary conditions imposed at the hellenic arc our stress free modelling suggests a scenario for the evolution of the naf 1 at an earlier stage before the naf had reached the aegean it was not under the influence of hellenic arc pull its slip rate profile is modelled to have a half elliptical shape corresponding to a crack in elastic solid and an elastically strained anatolian lithosphere 2 the present day naf penetrates the aegean and a large process zone has developed due to interaction with the aegean extension and the hellenic arc pull elastic strains in the anatolian lithosphere are relaxed and the naf resembles a transform fault the models that we present suggest that changes in subduction zone behaviour should influence all of the boundaries associated with anatolian extrusion

a late holocene slip rate for the central north anatolian fault at tahtakopru turkey from cosmogenic 10be geochronology implications for fault loading and strain release rates 1 measurement of a stream offset and cosmogenic dating 10be of the alluvial surface into which the stream incised yield a preferred late holocene slip rate of 18 6 3 5 3 3 mm a 1 for the central part of the north anatolian fault naf at tahtakopru turkey use of variable cosmogenic production rate vpr models yields a slightly slower rate of 16 4 6 4 4 5 mm a 1 the offset drainage karanlik dere which flows southward almost perpendicular to the east west trace of the naf at the site is displaced right laterally by 55 10 m with no vertical displacement a 10be age of 3 ka 3 5 ka vpr from the top of a boulder on the best preserved part of the incised alluvial surface provides the most reliable maximum age for the onset of incision 11 10be ages from cobbles collected from the cultivated surface to the south yield younger ages consistent with exhumation erosion and mechanical mixing during plowing our 18 6 3 5 3 3 mm a 1 rate is similar to other geologic slip rates measured along the naf all of which cluster between 15 and 20 mm a 1 over a wide range of 103 105 timescales all of these geological rates however are slower than the 25 2 mm a 1 short term rate of elastic strain accumulation measured geodetically this disparity suggests the possibility that the naf is experiencing a strain transient in which the lower crust beneath the fault is deforming faster than its long term rate

reassessment of earthquakes 1900 1999 in the eastern mediterranean and the middle east summary we have reappraised locations and surface wave magnitudes of earthquakes this century in the eastern mediterranean and the middle east between 10 and 44 n and 18 and 70 e the results are presented in an improved parametric catalogue of shallow earthquakes h 40 km large enough ms 6 0 to be of interest in seismotectonics and earthquake engineering a considerable number of early events of 6 ms 7 2 not included in other catalogues have been identified and their magnitudes assessed we find that iss isc locations are systematically shifted by 10 30 km to the north or northeast of their macroseismic epicentres also we derived a regional average relationship between log m0 and ms we show that the correlation of magnitude with epicentral intensity is very weak as is expected and a source of error in frequency relations

a model for orbital pacing of methane hydrate destabilization during the palaeogene the early eocene was marked by a series of abrupt warming events numerical modelling suggests that the events were the result of nonlinear interactions between orbital forcing ocean circulation and the carbon cycle a series of transient global warming events1 2 occurred during the late palaeocene and early eocene about 59 to 50 million years ago the events although variable in magnitude were apparently paced by orbital cycles2 3 4 and linked to massive perturbations of the global carbon cycle5 6 however a causal link between orbital changes in insolation and the carbon cycle has yet to be established for this time period here we present a series of coupled climate model simulations that demonstrate that orbitally induced changes in ocean circulation and intermediate water temperature can trigger the destabilization of methane hydrates we then use a simple threshold model to show that progressive global warming over millions of years in combination with the increasing tendency of the ocean to remain in a more stagnant state can explain the decreasing magnitude and increasing frequency of hyperthermal events throughout the early eocene our work shows that nonlinear interactions between climate and the carbon cycle can modulate the effect of orbital variations in this case producing transient global warming events with varying timing and magnitude

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

slip distribution along the north anatolian fault associated with the large earthquakes of the period 1939 to 1967 abstract between 1939 and 1967 six large fault ruptures formed a westward migrating sequence of events along a 900 km long nearly continuous portion of the north anatolian fault for these events the 1939 erzincan 1942 niksar erbaa 1943 tosya 1944 bolu gerede 1957 abant and 1967 mudurnu valley earthquakes i have compiled a record of dextral slip which contains nearly 100 points these data indicate that the amount of slip is irregularly distributed along the 1939 to 1967 rupture zone the maximum slip 7 5 m occurred during the 1939 earthquake in the eastern 150 km of the 900 km long rupture zone dextral offsets diminish very abruptly eastward but very gradually westward the rate of westward decrease in the 1939 to 1967 offsets is only slightly greater than the rate of westward decrease of post miocene displacement along the north anatolian fault this suggests that westward decrease in slip can be expected to be a general characteristic of earthquake ruptures along the north anatolian fault in the future nevertheless within the 1939 to 1967 slip distribution there are three regions that had less slip than the neighboring regions these i interpret as possible sites of large future earthquakes one of these seismic gaps has already experienced another earthquake in 1951 and subsequent creep

near inertial oscillations over the texas louisiana shelf wind induced near inertial oscillations over the texas louisiana shelf in spring and summer 1992 are described using the current and wind observations taken during the first year of the texas louisiana shelf circulation and transport processes study latex a rotary spectral analysis shows clockwise rotating energy peaks at near inertial frequencies for records from all current meter moorings after the suppression of principal tidal signals the vertical structure of near inertial oscillations is characterized by a first baroclinic mode with a near 180 phase difference between the upper mixed layer and the lower stratified layer the oscillations are intermittent with a modulation timescale of about 5 10 days they are surface intensified and have maximum values near the shelf break decaying gradually toward the coast but rapidly offshore near inertial oscillations appear to accompany a sudden change of the wind stress during frontal passages diagnostic analysis suggests that the large near inertial oscillations over the latex shelf are mainly generated by high frequency near inertial variation of the wind stress accompanying the passage of atmospheric fronts when the downward transfer of the near inertial energy to the deep stratified layer is small a simple mixed layer model forced by the observed wind stress provides a reasonable prediction of the near inertial currents in the mixed layer

oceanic gas hydrate instability and dissociation under climate change scenarios 1 global oceanic deposits of methane gas hydrate clathrate have been implicated as the main culprit for a repeated remarkably rapid sequence of global warming effects that occurred during the late quaternary period however the behavior of contemporary oceanic methane hydrate deposits subjected to rapid temperature changes like those predicted under future climate change scenarios is poorly understood and existing studies focus on deep hydrate deposits under equilibrium conditions in this study we simulate the dynamic response of several types of oceanic gas hydrate accumulations to temperature changes at the seafloor and assess the potential for methane release into the ecosystem the results suggest that while many deep hydrate deposits are indeed stable under the influence of rapid seafloor temperature variations shallow deposits such as those found in arctic regions or in the gulf of mexico can undergo rapid dissociation and produce significant carbon fluxes over a period of decades

sources of methane for marine gas hydrate inferences from a comparison of observations and numerical models the supply of methane for marine gas hydrate is commonly attributed to local conversion of organic material within the zone of stability or to migration of methane bearing fluids from a deeper source area however the relative importance of these methane sources is not well known we use numerical models for the formation of gas hydrate to assess the influence of methane supply on observable features of hydrate occurrences model predictions for the pore fluid chlorinity and the volumes of hydrate and free gas are compared with observations from the blake ridge and cascadia margin we find that the observations from the blake ridge can be explained with a deep methane source if a saturated fluid rises with a velocity of 0 26 mm yr 1 an equally good fit to the observations is obtained by combining in situ production of methane with an upward fluid velocity of 0 08 mm yr 1 which is compatible with estimates of fluid velocity at site 997 observations from the cascadia margin can be explained with a deep methane source if the upward fluid velocity is 0 42 mm yr 1 the predicted volume of hydrate 2 of the pore space is much smaller than some previous estimates and a layer of free gas 1 of the pore space develops below the stability zone allowing for in situ production at the cascadia margin lowers the upward fluid velocity 0 35 mm yr 1 needed to explain the pore water chlorinity

fault displacement rates on a range of timescales abstract displacements on tectonic faults primarily accrue during earthquakes at rates that vary through time to examine the processes that underlie the temporal changes in fault displacement rates we analyse displacements and displacement rates for time periods from the present to 5 10 20 300 500 1000 and 5000 kyr for 261 active reverse or normal faults from a worldwide dataset displacement rates depart from million year average rates by up to three orders of magnitude with the size of these departures inversely related to the duration of the sample period and to fault length short term 20 kyr displacement rates generally span a greater range on small faults than large a feature which suggests more variable growth on smaller faults simple earthquake slip modeling shows that variations in displacement rates require changes in both recurrence interval and slip per event and do not support the characteristic slip earthquake model as long as fault system strain rates are uniform displacement rates generally become constant over time periods between 20 and 300 kyr with the length of time required to reach stability being inversely related to the regional basin wide strain rates stable long term displacement rates and fluctuations in earthquake recurrence intervals and slip arise in part due to fault interactions

ocean oxygen depletion due to decomposition of submarine methane hydrate global warming could decompose submarine methane hydrate and cause methane release into the ocean the released methane causes oxygen depletion via oxidation however its global impact is yet to be quantitatively investigated we have projected the potential impact of oxygen depletion due to methane hydrate decomposition via numerical modeling we find that the global methane hydrate inventory decreases by approximately 70 35 under four times twice the atmospheric co2 concentration and is accompanied by significant global oxygen depletion on a timescale of thousands of years in particular we demonstrate the great expansion of suboxic and hypoxic regions having adverse impact on marine organisms and ocean biogeochemical cycles this is because hydrate decomposition primarily occurs in the pacific ocean where present day seawater has low oxygen concentration besides the decrease in oxygen solubility and reduced ventilation associated with global warming the process described in this study is also important in oxygen depletion

poseidon s horses plate tectonics and earthquake storms in the late bronze age aegean and eastern mediterranean abstract in light of the accumulated evidence now published the oft denigrated suggestion that major earthquakes took place in the aegean and eastern mediterranean areas during the late 13th and early 12th centuries bc must be reconsidered a new study of earthquakes occurring in the aegean and eastern mediterranean region during the 20th century utilizing data recorded since the invention of seismic tracking devices shows that this area is criss crossed with major fault lines and that numerous temblors of magnitude 6 5 enough to destroy modern buildings let alone those of antiquity occur frequently it can be demonstrated that such major earthquakes often occur in groups known as sequences or storms in which one large quake is followed days months or even years later by others elsewhere on the now weakened fault line when a map of the areas in the aegean and eastern mediterranean region affected i e shaken by 20th centuryad earthquakes of magnitude 6 5 and greater and with an intensity of vii or greater is overlaid on robert drews map of sites destroyed in these same regions during the so called catastrophe near the end of the late bronze age it is readily apparent that virtually all of these lba sites lie within the affected high shaking areas while the evidence is not conclusive based on these new data we would suggest that an earthquake storm may have occurred in the late bronze age aegean and eastern mediterranean during the years 1225 1175bc this storm may have interacted with the other forces at work in these areas c 1200bc and merits consideration by archaeologists and prehistorians

arecibo s thermospheric gravity waves and the case for an ocean source 1 wave like disturbances in electron density ne have been observed in the thermosphere above arecibo observatory puerto rico throughout its 45 year history however only recently has it become evident that these waves are continuously present in the arecibo thermosphere the wave characteristics are fairly constant between day and night and from season to season high resolution electron density measurements obtained by applying the coded long pulse radar technique to photoelectron enhanced langmuir waves are presented these new observations strongly suggest that the perturbations in electron density are the result of internal acoustic gravity waves agws propagating through the arecibo thermosphere the agws appear to be broadbanded in wave number space the downward phase trajectories of ne ne between 400 and 120 km combined with the low horizontal phase velocities obtained from airglow measurements support the idea that the agws are not ducted but rather are locally produced in addition the altitudes at which major peaks in ne ne are observed follow theoretical estimates for nonducted waves the nominal period of the agws is 60 min at 250 km altitude but periods of 20 min are also evident at lower attitudes classic sources of agws do not appear to be consistent with the arecibo observations of a continuous flux of background agws ray tracing of the agws combined with 630 0 nm airglow observations point to a source location in the atlantic ocean that is roughly 2100 km east northeast of arecibo internal ocean waves generated in response to the internal tide at the mid atlantic ridge are the most likely source of arecibo s thermospheric agws

contributions of denitrification and mixing on the distribution of nitrous oxide in the north pacific 1 we analyzed n2o isotopomer ratios distribution of isotopes within n2o molecules in the eastern tropical north pacific the n2o isotopomer ratios indicate the contribution of denitrification in the oxygen minimum zone omz 600 m in depth in the western north pacific which is not consistent with the widely accepted nitrification hypothesis our models indicate that the n2o yield per mole o2 consumed dn2o do2 is 0 008 0 0 015 nmol mol during remineralization and nitrification in the western north pacific nitrification in aerobic deep waters is a minor source of oceanic n2o whereas the n2o production in the omz is the dominant factor for the oceanic n2o distribution the denitrification in the omz is consistent with the correlation between n2o level above atmospheric equilibrium and aou apparent oxygen utilization and the parallel 18o enrichment of n2o and o2 in the omz which have been believed to support the nitrification hypothesis

nonlinear motions at the internal tide source 1 oceanic internal tidal wave generation is commonly modeled via interaction of a sinusoidal barotropic vertical velocity w with topography however general w above slopes are predominantly nonlinear as appears in some nonhydrostatic models here 1 2 hz sampled observations are presented from 2 84 m above the bottom mab at 1400 m at the bay of biscay continental slope fronts are observed that all propagate upslope having heights 50 mab and more or less 5 occurring at the tidal periodicity they are accompanied by o 10 min pulses of w 0 10 m s 1 w and irregular small scale waves superimposed on an asymmetric tidal signal this nonlinearity is further exemplified by variations in frontal arrival and steepness height form and is causing i internal tidal intermittency of 10 tidal periods ii nonlinear generation of internal tidal higher harmonics at the source the observations suggest internal tide generation in a broadband instead of a monochromatic beam

near inertial current oscillations off the mid east coast of korea abstract near inertial current oscillations were observed at depths of 620 and 790 m at a current meter mooring station in water 840 m deep off the mid east coast of korea the oscillatory inertial motions with an amplitude of up to 8 cm s existed during 73 days between august 27 and november 7 of 1986 with a large temporal variation in speed spectral analysis of the data was conducted and the result showed that the most dominant signal in the records was clockwise rotation whose frequency was close to the inertial frequency the peak frequency of the near inertial oscillations was slightly greater than the local inertial frequency f 0 0511 cph by 2 5 these clockwise oscillations had the mean amplitude of about 2 5 cm s reaching an instantaneous maximum of 7 5 cm s the mean ratio of the semi major axis to the semi minor one was found to be about 1 2 and the mean direction of the major axis was nearly parallel to the isobaths around the mooring station high near inertial energy parallel continuously during the first 15 days and then appeared in the form of group wave packets lasting several days during the remaining period three prominent events of wave packets were more energetic at the deeper depth the phase difference between the two horizontal near inertial current vectors changed largely with time but it remained relatively constant during each of the three energetic events changing its sign from one event to another the horizontal near inertial current vector rotated clockwise with increasing depth during one event but counterclockwise during the other two events the corresponding phase propagation was upward with a phase speed of 2 5 cm s for the clockwise polarization with depth but downward with 1 8 and 1 1 cm s for the counterclockwise rotating events

recent behavior of the north anatolian fault insights from an integrated paleoseismological data set 1 the north anatolian fault naf is a right lateral plate boundary fault that arcs across northern turkey for 1500 km almost the entire fault progressively ruptured in the 20th century its cascading style indicating that stress from one fault rupture triggers fault rupture of adjacent segments using published paleoseismic investigations this study integrates all of the existing information about the timing of paleoearthquakes on the naf paleoseismic investigation data are compiled into a database and for each site a bayesian ordering constrained age model is constructed in a consistent framework spatial variability of recurrence intervals suggests a spatial pattern in the behavior of earthquakes on the naf that may correspond to the tectonic provinces within the anatolian plate in the west the shear stress associated with the escaping anatolian plate interplays with the tensile stress associated with the aegean extensional province along this western transtensional section we recognize short recurrence intervals and switching between the furcated fault strands the central section of the naf is translational with little influence of fault normal stresses from other tectonic sources this section tends to rupture in unison or close succession the eastern section of the naf is transpressional due to the compressional fault normal stress associated with the indenting arabian plate along this section the recurrence intervals are bimodal which we attribute to variable normal stress although there are other possible causes

late holocene slip rate for the north anatolian fault turkey from cosmogenic 36cl geochronology implications for the constancy of fault loading and strain release rates geomorphologic mapping and cosmogenic radionuclide 36cl dating of an offset fluvial terrace yield a preferred late holocene slip rate of 20 5 5 5 mm yr for the central part of the north anatolian fault turkey an independent slip rate constrained by 14c ages is 20 5 8 5 mm yr these rates are generally similar to but possibly slightly slower than the short term rate of elastic strain storage of 25 1 measured geodetically across this major strike slip fault reilinger et al 2006 1 suggesting that loading and strain release on this part of the north anatolian fault have been relatively constant when averaged over the past 2 2 5 k y we attribute this consistency to the relatively simple structure of the anatolia eurasia plate boundary in north central turkey where almost all plate boundary strain is accommodated along the north anatolian fault the absence of other moderate to high slip rate faults and the earthquakes they produce leads to a relatively simple stress evolution for the fault dominated by steady tectonic loading 1 ref 10

observations of near inertial internal gravity waves radiating from a frontal jet abstractshipboard adcp and towed ctd measurements are presented of a near inertial internal gravity wave radiating away from a zonal jet associated with the subtropical front in the north pacific three dimensional spatial surveys indicate persistent alternating shear layers sloping downward and equatorward from the front as a result depth integrated ageostrophic shear increases sharply equatorward of the front the layers have a vertical wavelength of about 250 m and a slope consistent with a wave of frequency 1 01f they extend at least 100 km south of the front time series confirm that the shear is associated with a downward propagating near inertial wave with frequency within 20 of f a slab mixed layer model forced with shipboard and ncep reanalysis winds suggests that wind forcing was too weak to generate the wave likewise trapping of the near inertial motions at the low vorticity edge of the front can be ruled out because of the extension of the features well south of it instead the authors

on the nature of near inertial oscillations in the uppermost part of the ocean and a possible route toward hf radar probing of stratification abstractinertial band response of the upper ocean to changing wind is studied both theoretically and by analysis of observations in the northwestern mediterranean on the nontraditional f plane because of the horizontal component of the earth s rotation for waves of inertial band with frequencies slightly below the local inertial frequency f there is a waveguide in the mixed layer confined from below by the pycnocline it is argued that when the stratification is shallow these waves are most easily and strongly excited by varying winds as near inertial oscillations nios these motions have been overlooked in previous studies because they are absent under the traditional approximation the observations that employed buoys with thermistors adcps and two 16 3 mhz wellen radar wera hf radars were carried out in the gulf of lion in april june 2006 the observations support the theoretical picture a pronounced inertial band response occurs only in the presence of shallow stratification and is confined

shallow ocean response to tropical cyclones observed on the continental shelf of the northwestern south china sea based on observed temperature and velocity in 2005 in northwestern south china sea the shallow ocean responses to three tropical cyclones were examined the oceanic response to washi was similar to common observations with 2 degrees c cooling of the ocean surface and slight warming of the thermocline resulted from vertical entrainment moreover the wavefield was dominated by first mode near inertial oscillations which were red shifted and trapped by negative background vorticity leading to an e folding timescale of 12 days the repeated reflections by the surface and bottom boundaries were thought to yield the successive emergence of higher modes the oceanic responses to vicente appeared to be insignificant with cooling of the ocean surface by only 0 5 degrees c and near inertial currents no larger than 0 10 m s as a result of a deepened surface mixed layer however the oceanic responses to typhoon damrey were drastic with cooling of 4 5 degrees c near the surface and successive barotropic like near inertial oscillations during the forced stage the upper ocean heat content decreased conspicuously by 11 65 and the stratification was thoroughly destroyed by vertical mixing in the relaxation stage the water particle had vertical displacement of 20 30 m generated by inertial pumping the current response to damrey was weaker than washi due to the deepened mixed layer and the destroyed stratification our results suggested that the shallow water oceanic responses to tropical cyclones varied significantly with the intensity of tropical cyclones and was affected by local stratification and background vorticity

the benthic boundary layer and sediment transport the major problems facing scientists studying marine boundary layer fluid mechanics in 1979 concerned the specific mechanismic operating in the regions of the top and the bottom of the boundary layer at the top the mechanisms of fluid escapement from the boundary layer and mixing into the ocean interior could only be postulated approximations of diffusivity across the top of the layer were being debated the values of which were more articles of faith than physically validated estimates cf armi 1979 garrett 1979 at the bottom the intermittent generation of stress cf gordon 1975 heathershaw and simpson 1979 was held responsible for the wide variability observed in the drag coefficient and the thickness of the viscous sub layer was claimed to be greater than that traditionally found from laboratory studies caldwell and chriss 1979

stepwise atmospheric carbon isotope excursion during the toarcian oceanic anoxic event early jurassic polish basin abstract during the mesozoic 250 64 ma intervals of about 0 5 myr were subject to severe environmental changes including high sea surface temperature and very low oxygen content of marine water these oceanic anoxic events or oaes occurred simultaneously with profound disturbance to the carbon cycle the carbon isotope anomaly in the early jurassic that marks the toarcian oceanic anoxic event t oae at 182 ma is characterized in marine sections by a series of dramatic steps towards lighter values herein we present new carbon isotope data from terrestrial organic matter phytoclast separates collected through a late pliensbachian middle toarcian coastal and marginal marine succession in the polish basin a setting where hinterland climate and sea level change are well recorded the results show that the shift to light carbon isotope values in the woody organic matter and therefore also in atmospheric carbon dioxide similarly occurred in major steps the steps are here correlated with those identified from marine organic matter where they have previously been attributed to 100 kyr eccentricity forcing of climate the results provide strong support for orbitally and climatically controlled release of isotopically light carbon from gas hydrates into the ocean atmosphere system in a series of rapid bursts additionally a link between the carbon isotope steps and shoreline movements can be demonstrated individual peaks of the negative excursion are mostly associated with facies indicative of sea level rise flooding surfaces however at the same time inferred higher atmospheric carbon dioxide content may be expected to have resulted in increased rainfall and temperature leading to accelerated weathering and erosion and consequently increased sediment supply progradation and regression causing some mismatches between isotope shifts and inferred sea level changes enhanced abundance of megaspores derived from hydrophilic plant groups and marked increase in kaolinite are coincident with the overall development of the negative isotope excursion the combined data suggest that each 100 kyr cycle in carbon isotope values was characterized by increasingly severe palaeoclimatic change culminating in extremely hot and humid conditions co incident with the peak of the final most negative carbon isotope excursion the chemostratigraphic correlation allows very precise dating of the late pliensbachian middle toarcian coastal and marginal marine sedimentary succession in the polish basin

tectonic evolution of the niksar and tasova erbaa pull apart basins north anatolian fault zone their significance for the motion of the anatolian block abstract the tasova erbaa and niksar basins are two adjacent pull apart basins along the north anatolian fault zone nafz within the tasova erbaa basin sedimentary lithofacies of the upper pontus formation plio pleistocene are asymmetrically distributed with laterally derived alluvial fans coarse braid plain deposits and axial braided stream deposits dominating the northern and western parts of the basin the basin has gently dipping sediments locally affected by pervasive extensional t faulting isolated compressional structures are associated with master faults deformation zone width 500 m pervasive extensional faults t and r and late stage pdz parallel compressional faults are also present an additional set of extensional faults trends perpendicular to the pdz accommodating secondary pull apart stretching within the basin the distribution of sedimentary facies and structural styles is consistent with that predicted by models for pull apart basins the adjacent niksar basin is an active pull apart basin possibly as young as 0 5 1 ma its modern drainage and sedimentary facies are symmetrically arranged adding the lengths of the tasova erbaa and niksar basin suggests 80 km total displacement along the north anatolian fault which is consistent with seymen itu ph d thesis 1975 sengor j geol soc 136 1979 269 282 and armijo et al tectonophysics 243 1999 135 154 who observed about 85 5 km total displacement along the north anatolian fault the change in course of the north anatolian fault marked by the formation of the niksar ezinepazari segment and this new geometry suggest that the anatolian block is rotating anticlockwise by having two separate poles one located near damascus and the other occurring north of the sinai peninsula this change may also mark the transfer of the anatolian triple junction from erzincan to karliova about 1 ma ago furthermore it appears that while the fault shortcuts the older basin a new generation of pull apart basins is formed due to changes of boundary conditions along the fault zone

gas hydrate dissociation prolongs acidification of the anthropocene oceans anthropogenic warming of the oceans can release methane ch4 currently stored in sediments as gas hydrates this ch4 will be oxidized to co2 thus increasing the acidification of the oceans we employ a biogeochemical model of the multimillennial carbon cycle to determine the evolution of the oceanic dissolved carbonate system over the next 13 kyr in response to co2 from gas hydrates combined with a reasonable scenario for long term anthropogenic co2 emissions hydrate derived co2 will appreciably delay the neutralization of ocean acidity and the return to preindustrial like conditions this finding is the same with ch4 release and oxidation in either the deep ocean or the atmosphere a change in caco3 export coupled to ch4 release would intensify the transient rise of the carbonate compensation depth without producing any changes to the long term evolution of the carbonate system overall gas hydrate destabilization implies a moderate additional perturbation to the carbonate system of the anthropocene oceans

the seismic activity of the marmara sea region over the last 2000 years we examined the seismicity of the region of the sea of marmara in northwest turkey over the last 2000 yr using the historical record of the region we found no evidence for truly large earthquakes of a size comparable to those in the north anatolian fault zone in the marmara basin events are smaller in keeping with the known fault segmentation of the basin over the last 2000 yr seismic mo ment release accounted for the known right lateral shear velocity across the marmara region observed by global positioning system measurements its average rate is relatively constant and varies between 1 6 and 2 4 cm yr the long term seismicity in the marmara sea region shows that large earthquakes are less frequent than pre dicted from the 100 yr long instrumental period

strike slip fault geometry in turkey and its influence on earthquake activity the geometry of turkish strike slip faults has been reviewed and described from this data set it appears that fault geometry the distribution of discontinuities such as bends and stepovers along the main fault trace plays an important role in controlling the location of large earthquake rupture segments along the fault zones large earthquake ruptures generally do not propagate past individual stepovers that are wider than 5 km or bends that have angles greater than about 30 more important than the size of each discontinuity however is the total geometric pattern i e the distribution of adjacent bends and stepovers based not only on distance from one another but also on relative discontinuity size certain geometric patterns restraining single or double bends are particularly common and can be viewed as responsible for strain accumulation along portions of the fault zone fault geometry not only plays a role in the extent of earthquake rupture but also in characteristics of earthquake behavior for example large earthquake epicenters often occur near restraining bends or double bends furthermore aftershocks and swarm activity can often be associated with releasing areas areas along the strike slip fault that are undergoing a relatively large amount of extension

southern peru desert shattered by the great 2001 earthquake implications for paleoseismic and paleo el nino southern oscillation records in the desert region around the coastal city of ilo the great southern peru earthquake of june 23 2001 8 2 8 4 moment magnitude produced intense and widespread ground failure effects these effects included abundant landslides pervasive ground cracking microfracturing of surficial hillslope materials collapse of drainage banks over long stretches widening of hillside rills and lengthening of first order tributary channels we have coined the term shattered landscape to describe the severity of these effects long term consequences of this landscape shattering are inferred to include increased runoff and sediment transport during postearthquake rainstorms this inference was confirmed during the first minor postearthquake rainstorm there which occurred in june and july of 2002 greater amounts of rainfall in this desert region have historically been associated with el nino events previous studies of an unusual paleoflood deposit in this region have concluded that it is the product of el nino generated precipitation falling on seismically disturbed landscapes the effects of the 2001 earthquake and 2002 rainstorm support that conclusion

mechanisms controlling export production at the lgm effects of changes in oceanic physical fields and atmospheric dust deposition 1 using a biogeochemical ocean model that includes the iron cycle we carry out preindustrial control ctl and glacial last glacial maximum lgm climate simulations focusing on changes in export production ep the model successfully reproduces general trends of a paleoclimate reconstruction of ep at the lgm except over the atlantic ocean by conducting a series of sensitivity simulations we investigate the mechanism controlling ep at the lgm in each basin in the southern ocean the model successfully reproduces the dipole pattern of the paleoreconstruction the higher latitude decrease and lower latitude increase of ep it is found that the lower latitude increase of ep comes from iron fertilization effects by enhanced dust deposition while the higher latitude decrease of ep is caused by the reduction of surface shortwave due to spreading of sea ice there we also find that increased dust input in other basins remotely affects ep in the southern ocean in the pacific ocean the model suggests that iron fertilization effects are dominant in open ocean regions in the atlantic ocean the model simulates overall reduction of ep whereas the paleoreconstruction suggests the increase in some regions we propose that the atlantic response is strongly affected by distribution of iron limitation in a control climate in our ctl simulation the biological production is limited not by iron but by phosphate in the atlantic ocean which leads to the decrease of ep in spite of the significant increase of dust deposition there it is implied that the accurate evaluation of iron limitation in the present ocean is critical for evaluating changes in ep and associated reduction of atmospheric co2 concentration at the lgm

modeling of methane bubbles released from large sea floor area condition required for methane emission to the atmosphere article i nfo massive methane release from sea floor sediments due to decomposition of methane hydrate and thermal decomposition of organic matter by volcanic outgassing is a potential contributor to global warming however the degree of global warming has not been estimated due to uncertainty over the proportion of methane flux from the sea floor to reach the atmosphere massive methane release from a large sea floor area would result in methane saturated seawater thus some methane would reach the atmosphere in this study we discussed the possibility of the methane release from a large sea floor area to the atmosphere focusing on methane saturation in the water column necessary for a methane bubble to reach the atmosphere using a one dimensional numerical model integrated over time we predict methane bubbles and methane concentration in the water column under the condition of continuous methane input from the sea floor to the water column we found that some methane bubbles reach the atmosphere even when the methane saturation fraction in the water column is much lower than 100 we compared the methane input from the sea floor required for a methane bubble to reach the atmosphere to the amount of methane in the sediment in the form of methane hydrate and free gas in most cases our results suggest that the typical amount of methane in the sediment i e typical hydrate fraction of 2 and free gas of two thirds of the amount of hydrate is significantly lower than the required minimum methane input it is therefore suggestedthat exceptinthecaseofanextraordinarymethane flux themassivequantityof methanebubbles released from sea floor gas hydrate would not reach the atmosphere directly but would be dissolved in the seawater with regard to global warming due to human activities the release of methane bubbles due to methane hydrate decomposition may not be enough to significantly accelerate total global warming in the case of metamorphic methane release during petm there is the possibility that the released methane resulted in methane saturated seawater allowing some methane to reach the atmosphere

influence of releasing step overs on surface fault rupture and fault segmentation examples from the 17 august 1999 izmit earthquake on the north anatolian fault turkey the 17 august 1999 izmit earthquake broke four distinct structural segments of the north anatolian fault from east to west the karadere sakarya sapanca and golcuk fault segments these segments are separated from one another and the adjoining yalova and duzce fault segments to the west and east respectively by distinct right releasing step over and or gaps in the fault trace these include from east to west the eften lake step over 2 4 km wide akyazi gap 6 13 km long sapanca step over 1 2 km wide golcuk step over 1 2 km wide and karamursel step over 4 5 km wide the earthquake nucleated within or near the golcuk step over with bilateral rupture propagation to the west and east to the west about 4 5 5 m of surface rupture up to 7 m of subsurface rupture on the golcuk segment was mostly if not entirely arrested by the 4 to 5 km wide karamursel step over to the east about 3 4 m of surface rupture about 4 m of subsurface rupture propagated through the 1 to 2 km wide sapanca step over triggering up to 4 5 5 5 m of surface rupture up to 5 6 m of subsurface rupture on the sakarya segment rupture on the sakarya segment stepped across the akyazi gap triggering 1 1 5 m of rupture on the karadere segment rupture on the karadere segment was arrested by the 2 to 4 km wide eften lake step over modeling of the transient stress field associated with the rupture propagation agrees well with the field observations the modeled fault rupture of 5 m on the golcuk segment appears to decrease the transient stress on the eastern tip of the adjoining yalova segment across the 4 to 5 km wide karamursel step over even if we allow rupture on the golcuk segment to extend along the entire southern margin of the step over our model shows that regardless of the amount of slip in a generic sense it is difficult to increase stress on the tip of an adjoining fault segment across a 5 km wide step over on the other hand fault rupture of 3 m on the western tip of the sapanca fault segment significantly increases the transient stress on the adjoining sakarya segment across the 1 to 2 km wide sapanca step over allowing rupture propagation across the basin an evaluation of 30 historical strike slip earthquakes involving 59 step over basins supports our field observations and stress modeling of the izmit fault rupture historical strike slip events with small to large displacements usually propagate through step overs less than 1 2 km wide with increasing displacement larger and larger step overs can be ruptured through the empirical data generally show a ratio ranging from 2 1 to 1 1 between step over width in kilometers and strike slip displacement in meters for a through going rupture however step overs of 4 to 5 km width appear to always arrest fault rupture regardless of the amount of displacement these results therefore provide important constraints for evaluating the probability of multisegment ruptures on segmented strike slip faults manuscript received 20 august 2000

gps constraints on continental deformation in the africa arabia eurasia continental collision zone and implications for the dynamics of plate interactions 1 the gps derived velocity field 1988 2005 for the zone of interaction of the arabian african nubian somalian and eurasian plates indicates counterclockwise rotation of a broad area of the earth s surface including the arabian plate adjacent parts of the zagros and central iran turkey and the aegean peloponnesus relative to eurasia at rates in the range of 20 30 mm yr this relatively rapid motion occurs within the framework of the slow moving 5 mm yr relative motions eurasian nubian and somalian plates the circulatory pattern of motion increases in rate toward the hellenic trench system we develop an elastic block model to constrain present day plate motions relative euler vectors regional deformation within the interplate zone and slip rates for major faults substantial areas of continental lithosphere within the region of plate interaction show coherent motion with internal deformations below 1 2 mm yr including central and eastern anatolia turkey the southwestern aegean peloponnesus the lesser caucasus and central iran geodetic slip rates for major block bounding structures are mostly comparable to geologic rates estimated for the most recent geological period 3 5 myr we find that the convergence of arabia with eurasia is accommodated in large part by lateral transport within the interior part of the collision zone and lithospheric shortening along the caucasus and zagros mountain belts around the periphery of the collision zone in addition we find that the principal boundary between the westerly moving anatolian plate and arabia east anatolian fault is presently characterized by pure left lateral strike slip with no fault normal convergence this implies that extrusion is not presently inducing westward motion of anatolia on the basis of the observed kinematics we hypothesize that deformation in the africa arabia eurasia collision zone is driven in large part by rollback of the subducting african lithosphere beneath the hellenic and cyprus trenches aided by slab pull on the southeastern side of the subducting arabian plate along the makran subduction zone we further suggest that the separation of arabia from africa is a response to plate motions induced by active subduction

near inertial motions off the oregon coast near inertial motions were observed at all current meters in an array of five moorings spanning the continental margin off central oregon during october 1977 to january 1978 all moorings were between 10 and 130 km from shore in water depths between 100 m and 2500 m largest near inertial amplitudes 30 cm s were observed at the uppermost current meters of the offshore moorings although these were below the surface mixed layer the near inertial energy generally decreased with increasing depth and there was less near inertial energy over the continental shelf than at similar depths offshore the energy levels observed over the shelf were about the same as observed there during summer 1973 and the energy levels observed offshore were comparable with those observed in the open north atlantic horizontal coherence scales were large exceeding 115 km during the first half of the observational period and about 60 km during the second half estimates of the horizontal wavelength 50 km during the first half and 20 km during the second hal0 suggest that the coherence scale is of the order of three wavelengths although we did not have current data in the surface mixed layer nor wind measurements over each mooring the available meteorological data synoptic pressure charts and hourly wind and pressure at newport suggest that most of the near inertial energy was forced by the local wind

the repetition of large earthquake ruptures abstract this survey of well documented repeated fault rupture confirms that some faults have exhibited a characteristic behavior during repeated large earthquakes that is the magnitude distribution and style of slip on the fault has repeated during two or more consecutive events in two cases faults exhibit slip functions that vary little from earthquake to earthquake in one other well documented case however fault lengths contrast markedly for two consecutive ruptures but the amount of offset at individual sites was similar adjacent individual patches 10 km or more in length failed singly during one event and in tandem during the other more complex cases of repetition may also represent the failure of several distinct patches the faults of the 1992 landers earthquake provide an instructive example of such complexity together these examples suggest that large earthquakes commonly result from the failure of one or more patches each characterized by a slip function that is roughly invariant through consecutive earthquake cycles the persistence of these slip patches through two or more large earthquakes indicates that some quasi invariant physical property controls the pattern and magnitude of slip these data seem incompatible with theoretical models that produce slip distributions that are highly variable in consecutive large events