the progressive evolution of a continental climate in southeast central european lowlands during the middle pleistocene recorded in loess paleosol sequences 1 abstract little is known about the long term quaternary climate evolution of central and south east europe because suitable terrestrial paleoenvironmental records are scarce we present a multiproxy record of loess paleosol sequences in the middle and lower danube basins over the past 700 k y in these lowlands the continentality of interglacial climate progressively increased during the middle pleistocene corresponding trends are seen in other climate prox ies in the same region and in the lowlands of the northern black sea but not or less clearly in climate archives from outside these lowlands we conclude that a small scale increase in paleoelevation of central european mountain ranges the alps carpathians and dinarides during the middle pleistocene might be the cause of the progressive increase in climate conti nentality of southeast european lowlands

dust flux estimates for the last glacial period in east central europe based on terrestrial records of loess deposits a review loess paleosol sequences are significant records of the mineral dust cycle of glacial interglacial periods as dust particles give rise to direct and indirect radiative forcing obtaining a reliable picture of the global and regional patterns of mineral dust fluxes during glacial periods can lead to a better understanding of the contribution of mineral dust to past climate changes recent progress in absolute dating of loess deposits in the carpathian basin in east central europe made it possible to provide correct aeolian flux estimates for the last glacial period marine isotope stage mis 2 mass accumulation rates mars from chronological data of 33 loess sites exhibited a wide range of values from 150 to 1422 g m 2 a 1 centered around median and mean values of 338 and 417 g m 2 a 1 marpm10marpm10 and marpm2marpm2 estimates have been also calculated using grain size measurements of many loess samples and loess mars in order to facilitate comparison with models and since particles larger than 10 m have a negligible radiative effect here we show that some previous model simulations of the dust cycle at the last glacial maximum lgm significantly underestimated the real aeolian flux ranges of our estimates marpm10 34 324marpm10 34 324 and marpm2 9 3 88 2gm 2a 1 in east central europe for this reason some simulations of dust induced direct radiative forcing of the lgm climate failed to yield reliable results for this mid latitude region as they have been based on three dimensional dust field models that are not capable of estimating the real aeolian fluxes in central europe a recent global model of top of the atmosphere toa radiative forcing by mineral aerosols at the lgm that has been based on more realistic parameterization of dust sources transport and deposition revealed zonally averaged surface cooling of 2 c for the latitudes of our study area this surface cooling and toa radiative forcing 2 to 3 w m 2 are greater than recognized in other models and draws our attention to the importance of further modeling the impact of mineral dust on lgm climate in order to gain insight into the spatial pattern of radiative forcing and better understand resulting climate response in mid latitude loess regions such as east central europe

new slip rate estimates for the creeping segment of the san andreas fault california new continuous and differential global positioning system gps measurements of recent slip rates and 30 yr alignment array offsets from the central creeping segment of the san andreas fault yield a maximum right lateral slip rate of 25 1 mm yr this slip rate is 20 slower than the 30 mm yr slip rate accepted for this segment of the fault and 35 slower than the 39 mm yr slip rate predicted between the sierra nevada great valley block and the pacific plate new continuous gps measurements between pairs of sites that flank the creeping segment at intersite distances of 1 0 km and 70 km give relative fault parallel slip rates of 28 2 and 30 2 mm yr respectively these observations indicate that right lateral deformation rates increase with distance from the fault possible explanations for the gradient observed in the geodetic data are elastic strain accumulation along the creeping segment or significant distributed deformation on off fault structures

stratigraphy and spatial and temporal paleoclimatic trends in southeastern eastern european loess paleosol sequences abstract the loess paleosol sections batajnica stari slankamen serbia mircea voda romania and stary kaydaky ukraine are presently located in areas of different types of steppe and are highly sensitive for recording climatic changes a stratigraphy for these three southeastern eastern european sections is presented based on pedostratigraphy and correlation of recently obtained susceptibility records with susceptibility data of other sections of the area koriten mostistea vyazivok of the chinese loess plateau and with the benthic 18o record of odp 677 six pedocomplexes were studied at the serbian and romanian sections and five at the ukrainian section the oldest are related to marine isotope stage mis 17 batajnica stari slankamen and mircea voda and mis 13 15 stary kaydaky some points concerning the existing loess chronostratigraphies of bulgaria ukraine and china are discussed comparative study of the profiles allows the tracing of paleoclimatic and paleoenvironmental changes in southeastern eastern europe in time and space reconstruction of paleoprecipitation based on susceptibility rainfall relationships and calculations of sedimentation rates are evaluated

the crvenka loess paleosol sequence a record of continuous grassland domination in the southern carpathian basin during the late pleistocene abstract in this study we compare two independent paleoenvironmental proxies for a loess sequence in northern serbia in the southern carpathian basin novel n alkane biomarkers and traditional land snail assemblages both are associated with other more widely used proxy data for loess sections such as environmental magnetism grain size and geochemical indices together these paleoenvironmental proxy records provide evidence for the continued dominance of grasslands during the late pleistocene in the southern carpathian basin it is contrary to other european loess provinces which are characterized by high diversity of late pleistocene environments ranging from tundra like to deciduous forest habitats these findings highlight the southeastern part of carpathian basin as an important but still insufficiently investigated biogeographical refugium and biodiversity preservation zone the reason for this is a mostly stable paleoclimate for much of the late pleistocene

a physics based approach of deep interseismic creep for viscoelastic strike slip earthquake cycle models most geodetic inversions of surface deformation rates consider the depth distribution of interseismic fault slip rate to be time invariant however some numerical simulations show down dip penetration of dynamic rupture into regions with velocity strengthening friction with subsequent up dip propagation of the locked to creeping transition recently bruhat segall 2017 developed a new method to characterize interseismic slip rates that allows slip to penetrate up dip into the locked region this simple model considered deep interseismic slip as a crack loaded at its down dip end and provided analytical expressions for stress drop within the crack slip and slip rate along the fault this study extends this approach to strike slip fault environments and includes coupling of creep to viscoelastic flow in the lower crust and upper mantle we employ this model to investigate interseismic deformation rates along the carrizo plain section of the san andreas fault this study reviews possible models elastic and viscoelastic for fitting horizontal surface rates using this updated approach we develop a physics based solution for deep interseismic creep which accounts for possible slow vertical propagation and investigate how it improves the fit of the horizontal deformation rates in the carrizo plain region

weathering intensity and pedostratigraphy of the middle to upper pleistocene loess palaeosol sequence of wels aschet upper austria abstract on top of a fluvioglacial terrace near wels aschet a complex loess palaeosol sequence has been investigated to date the terrace is classified as a classical gunz unit older deckenschotter sedimentological and mineralogical analyses were carried out on the basis of palaeopedological field data the results show that in terms of mineralogical composition the palaeosols can clearly be differentiated and are characterised throughout by interglacial weathering intensity bulk mineralogical as well as clay mineralogical data allow a five stage ranking of weathering intensity based on indicator minerals from the bulk mineralogical perspective slightly weathered loess still contains carbonate minerals and primary chlorite whereas the intensely weathered soil horizons are characterised by the total or near absence of carbonate minerals and primary chlorite micas and feldspars in clay mineralogical results chlorite and the relation of 14 a and 18 a vermiculites as well as mixed layer minerals play an important role in determining the weathering stage primary chlorite can be present in slightly weathered loess loams and vermiculite 14 a is dominant there stage 1 and 2 from weathering stage 3 onwards the amount of vermiculite 18 a increases considerably and dominates the following stage 4 most intensive weathering causes the absence of illite stage 5 generally the studied interglacial palaeosols belong to at least stage 3 with the applied methodology four interglacial palaeosols have been demarcated as well as a highly weathered palaeosol within the terrace gravels of the gunz in wels aschet pedostratigrapy points to a classification of the older deckenschotter in mis 14 at minimum however since this glacial period was of low intensity and the weathering intensity of the basal palaeosol was significantly enhanced a correlation of the gunz terrace with mis 16 also seems possible

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

geologic versus geodetic deformation adjacent to the san andreas fault central california we combine geologic and global positioning system gps data to characterize the style and magnitude of off fault deformation across the san andreas fault system in central california geologic structures record 12 km of both fault parallel and fault perpendicular displacements across creeping and locked portions of the san andreas fault analysis of 150 gps site velocities suggests that the borderlands record 4 6 mm yr of fault parallel and 3 5 mm yr of fault perpendicular motion alongside the creeping segment where elastic strain is minimized the distribution of both long term geologic and short term geodetic deformation is affected by basement type where more deformation is concentrated northeast of the san andreas fault on franciscan basement we suggest that at least half the fault parallel gps deformation measured by gps bordering the creeping segment must be accommodated by geologic structures this permanent deformation needs to be incorporated into dynamic models of the fault system elastic modeling of the san andreas fault in central california which incorporates its well known transition from locked to creeping behavior near parkfield predicts first order variations in the gps velocity field along the fault and corresponding variations in dilatational strain rates the strain rate pattern is dominated by a large contractional region northeast of the transition from locked to creeping behavior and a large extensional region southwest of the transition the former coincides with the coalinga and kettleman hills anticlines the growth and development of which seem to have occurred under at least two kinematic conditions we suggest that the onset of fault creep in central california promoted the growth of these folds by implication fault creep has been active over geologic time scales

1855 and 1991 surveys of the san andreas fault implications for fault mechanics two monuments from an 1855 cadastral survey that span the san andreas fault in the carrizo plain have been right laterally displaced 11 0 2 5 m by the 1857 fort tejon earthquake and associated seismicity and afterslip this measurement confirms that at least 9 5 0 5 m of slip occurred along the main fault trace as suggested by measurements of offset channels near wallace creek the slip varied by 2 to 3 m along a 2 6 km section of the main fault trace using radiocarbon dates of the penultimate large earthquake and measurements of slip from the 1857 earthquake we calculate an apparent slip rate for the last complete earthquake cycle that is at least 25 lower than the late holocene slip rate on the main fault trace comparison of short term broad aperture strain accumulation rates with the narrow aperture late holocene slip rate indicates that the fault behaves nearly elastically over a time scale of several earthquake cycles therefore slip in future earthquakes should compensate the slip rate deficit from the 1857 earthquake

three dimensional investigation of a 5 m deflected swale along the san andreas fault in the carrizo plain topographic maps produced from light detection and ranging lidar data are useful for paleoseismic and neotectonic research because they pro vide submeter representation of faulting related surface features offset measurements of geomorphic features made in the field or on a remotely sensed imagery commonly assume a straight or smooth i e undeflected pre earthquake geometry here we present results from investigation of an 20 cm deep and 5 m wide swale with a sharp bend along the san andreas fault saf at the bidart fan site in the carrizo plain california from analysis of lidar topography images and field measure ments the swale was initially interpreted as a channel tectonically offset 4 7 m our observations from exposures in four backhoe excavations and 25 hand dug trenchettes show that even though a sharp bend in the swale coincides with the trace of the a d 1857 fault rupture the swale formed after the 1857 earthquake and was not tectonically offset subtle fractures observed within a surficial gravel unit overlying the 1857 rupture trace are similar to fractures previously documented at the phelan fan and ly4 paleoseismic sites 3 and 35 km northwest of bidart fan respectively collectively the fractures suggest that a post 1857 moderate magnitude earthquake caused ground cracking in the carrizo and cholame stretches of the saf our obser vations emphasize the importance of excavation at key locations to validate remote and ground based measurements and we advocate more geomorphic characterization for each site if excavation is not possible online material figures of trench logs

fault slip and earthquake recurrence along strike slip faults contributions of high resolution geomorphic data article i nfo understanding earthquake eq recurrence relies on information about the timing and size of past eq ruptures along a given fault knowledge of a fault s rupture history provides valuable information on its potential future behavior enabling seismic hazard estimates and loss mitigation stratigraphic and geomorphic evidence of faulting is used to constrain the recurrence of surface rupturing eqs analysis of the latter data sets culminated during the mid 1980s in the formulation of now classical eq recurrence models now routinely used to assess seismic hazard within the last decade light detection and ranging lidar surveying technology and other high resolution data sets became increasingly available to tectono geomorphic studies promising to contribute to better informed models of eq recurrence and slip accumulation patterns after reviewing motivation and background we outline requirements to successfully reconstruct a fault s offset accumulation pattern from geomorphic evidence we address sources of uncertainty affecting offset measure ment and advocate approaches to minimize them a number of recent studies focus on single eq slip distribu tions and along fault slip accumulation patterns we put them in context with paleoseismic studies along the respective faults by comparing coefficients of variation cv for eq inter event time and slip per event and find that a single event offsets vary over a wide range of length scales and the sources for offset variability differ with length scale b at fault segment length scales single event offsets are essentially constant c along fault offset accumulation as resolved in the geomorphic record is dominated by essentially same size large offset in crements and d there is generally no one to one correlation between the offset accumulation pattern constrained in the geomorphic record and eq occurrence as identified in the stratigraphic record revealing the higher resolution and preservation potential of the latter while slip accumulation along a fault segment may be dominated by repetition of large nearly constant offset increments timing of surface rupture is less regular

mixed layer illite vermiculite as a paleoclimatic indicator in the pleistocene red soil sediments in jiujiang southern china abstract the mineralogy and chemical composition of the jiujiang red soil sediments were investigated using x ray diffraction xrd x ray fluorescence xrf and inductively coupled plasma mass spectrometry icp ms mixed layer illite vermiculite i v was confirmed based on the conditions that a broad peak of 1 0 to 1 4 nm appeared in xrd after mg saturation and its d spacing did not change after glycol treatment but collapsed to 1 0 nm after heating owing to the loss of water and hydroxy cations from its interlayer the mixed layer i v contents fluctuate throughout the section but show a decreasing trend upwards suggesting decreased weathering towards the surface of the section the chemical index of alteration cia values and rb sr ratios also exhibit upward decreasing trends jointly revealing the climate shift from warm humid to cool dry from the middle to the late pleistocene although the general climate evolution can be evaluated by cia values and rb sr ratios sub climatic events within the jiujiang red soil sediments cannot be identified the sio2 al2o3 al2o3 fe2o3 and sio2 fe2o3 ratios clearly fluctuate along the section especially within the net like red soil sediments but they do not reveal multiple climate cycles this is because of an inhomogeneous distribution of sio2 al2o3 and fe2o3 in the white veins and the red matrix and also non uniform sampling the variation in the content of mixed layer i v show a strong positive correlation with changes in magnetic susceptibility of loess paleosol sediments and in marine oxygen isotope ratios revealing multiple sub climate cycles on a global scale since the middle pleistocene therefore the mixed layer i v contents not only reveal the whole climate trend documented in the red soil sediments since the middle pleistocene but also disclose the sub climate cycles related to the deposit pedogenesis process

stratigraphic evidence for seven meters of dextral slip on the san andreas fault during the 1857 earthquake in the carrizo plain the smallest geomorphic offsets along a 35 km section of the san andreas fault in the carrizo plain vary from 7 to 10 m our three dimensional excavation of alluvial deposits a few km southeast of wallace creek confirms that at least 6 6 to 6 9 m of dextral slip occurred there during the latest large earthquake in 1857 dates on detrital charcoal suggest that the last event prior to the 1857 earthquake occurred before a date within the range a d 1305 to 1623 the 3 m range in smallest offsets along this portion of the fault may reflect either a 3 m variation in slip along the san andreas in 1857 or 2 to 3 m of slip during an event prior to 1857 observations made after the recent landers earthquake are compatible with the hypothesis of large local variations in slip during a single earthquake but do not explain the cause of such variations off fault dextral rotations would be one plausible explanation however paleoseismic data in the carrizo plain are too sparse to allow rejection of the alternative hypothesis that slip in the event prior to 1857 was only 2 to 3 m an amount of slip which would be several times too small to fit a time predictable model

processes of loess lithogenesis during the pleistocene holocene southeast siberia regional studies have been conducted on loess deposits cohesive sands and loess like neoformations in the technogenesis zones in southeast siberia cryogenic processes and distribution of geological formations have been ascribed to influential factors of loess lithogenesis the processes of loess formation are active in the present environment

a palaeomagnetic study of the upper mesozoic succession in northern tunisia summary the upper mesozoic section from northern tunisia provided an upper jurassic palaeomagnetic pole of 65 2 s 20 3 e ag5 6 1 calculated from the means of normal and reversely magnetized samples from the uppermost callovian oxfordian kimmeridgian and portlandian rocks in general the only cretaceous rocks to yield acceptable results were the few samples collected from fresh outcrops a polarity sequence can be established for the upper jurassic which can be correlated with the oceanic keathley anomaly sequence one consequence of the proposed correlation of the oceanic anomaly with the terrestrial palaeomagnetic sequence is to suggest a slightly different age for the oxfordiankimmeridgian boundary one interpretation of the frequent intermediate directions of magnetization in the cretaceous sequence is that there may be a number of unrecognized short period reversals within the cretaceous and more particularly during the so called cretaceous normal period

malacological characteristics of the middle to upper pleistocene transitional interval mis 7 5 observed in the batajnica locality serbia abstract the batajnica loess section is one of the most complete middle and late pleistocene records known in the vojvodina region serbia the main aim of the malacological investigations was to study the latest middle pleistocene cold interval and to see how the mollusc successions reacted to the climate changes during the cold warm transition the deposits which belong to the upper part of pedocomplex v s2 v l2 loess and partly to the v s1 soil were sampled the penultimate glacial loess v l2 of the batajnica site corresponds to the cold interval marine isotope stage mis 6 the molluscs indicate moderate or sometimes warm climate and dry or moderate steppe like environment composed of adjacent mosaics of drier and humid habitats the mollusc complexes of v s2 soil mis 7c v l2 loess mis 6 and v s1 paleosol mis 5e show almost the same species composition which suggests the existence of a comparatively moderate or warm climate during the late middle pleistocene cold interval in contrast the mollusc complexes mis 6 from western and eastern europe have less species and few individuals compared with the batajnica section comparison with the late middle pleistocene mollusc associations from the northern and southern margins of the fruska gora mountain confirms its environmental originality the northern side of the mountain was characterized by a humid and relatively colder environment than the other areas of the vojvodina region batajnica irig and ruma the mollusc fauna obtained in the batajnica site suggests that this adjacent area represented a refugium for the thermophilous and arid tolerant species where they were able to survive during the cold periods of the pleistocene and thus confirms the hypothesis of p sumegi

pleistocene environmental dynamics recorded in the loess of the middle and lower danube basin abstract the substantial loess deposits of the middle and lower danube basin in southeastern europe represent one of the thickest and most comprehensive terrestrial palaeoenvironmental records on the continent yet are also the least well understood environmental conditions over the last million years have resulted in relatively continuous deposits uninterrupted by glaciation and tundra conditions which nevertheless reflect oscillations between relatively warm humid interglacial and cold dry glacial intervals this relative environmental stability may have proven important for hominins migrating into and through the region the loess stratigraphy comprises distinct loess paleosol sequences reflecting glacial interglacial phases which can be quantified for intensity using environmental magnetism and geochemistry these phases are emphasised by variations in vegetation and malacofauna which respond to climatic change the loess deposits demonstrate broadly similar sedimentological characteristics across the basin danubian loess deposits initiated in response to the tectonic formation of the pannonian basin retreat of the large palaeolakes and increased sediment supply from the danube the period from 1 ma 500 ka mis 27 13 was characterised by alternating loess deposition and pedogenesis during glacial and interglacial periods respectively in response to relatively humid forested conditions this period represents the opening of the danube corridor and provides the backdrop for initial hominin arrival into europe after 500 ka and particularly after mis 9 loess accumulation rates increased in response to relatively more steppic arid environments mis 9 and 13 15 were the most humid phases of the last 600 ky the mis 5 interglacial period was the warmest and relatively most humid period preceding the holocene and was followed by substantially increased loess accumulation during mis 4 which may be linked to north atlantic circulation the complexity of the mis 3 interstadial paleosol suggests that conditions were not uniformly warm and wet during this time mis 3 corresponds with the first arrival of anatomically modern humans to europe the last glacial maximum and younger dryas of mis 2 were characterised by substantially increased loess accumulation indicating cold steppe environments most likely influenced by the north atlantic although conditions were sufficiently mild that the region acted as a refugium for thermophilic biota as may also have been the case for most of the pleistocene glacial cycles the holocene soil represents relatively wamer and more humid conditions corresponding to the current interglacial

tectonic geomorphology of the san andreas fault zone from high resolution topography an example from the cholame segment abstract high resolution topographic data along fault zones are important aids in the delineation of recently active breaks a 15 km long portion of the south central san andreas fault saf along the southern cholame segment contains well preserved tectonic landforms such as benches troughs scarps and aligned ridges that indicate recurring earthquake slip recently acquired lidar topographic data along the entire southern saf b4 project have shot densities of 3 4 m 2 computed from the lidar returns digital elevation models dems of 0 25 to 0 5 m resolution using local binning with inverse distance weighting and 0 8 m or larger search radii depict the tectonic landforms at paleoseismic sites well enough to assess them confidently mapping of recently active breaks using a lidar only based approach compares well with aerial photographic and field based methods the fault zone varies in width from meters to nearly 1 km and is comprised of numerous en echelon meter to kilometer length overlapping sub parallel fault surfaces bounding differentially moving blocks that elongate parallel to the saf the semantic variations of what constitutes active and the importance of secondary traces influence the breadth and complexity of the resulting fault trace maps

pattern of orogenic rotations in central eastern sicily implications for the timing of spreading in the tyrrhenian sea new palaeomagnetic data from upper triassic to pliocene sediments reveal that in eastern sicily a major 70 clockwise cw rotation took place between oligocene and late tortonian time followed by a further 30 cw rotation results from central sicily are less coherent they show 44 83 post oligocene cw rotation local 14 post late tortonian counterclockwise ccw rotation and 25 post mid pliocene cw rotation we interpret the larger cw rotation observed in eastern sicily as related to a more internal palaeogeographical position with respect to central sicily our results complement pre existing data from the northwestern sicily carbonates and indicate that all the internal carbonate nappes coherently rotated by c 100 cw during tectonic emplacement implying a west to east increase of shortening in the sicilian maghrebian belt in sicily compressive deformation started during the langhian i e just after the deposition of the upper oligocene upper burdigalian numidian flysch turbidites therefore the age of the older 70 palaeomagnetic rotation synchronous to the thrusting is constrained to occur between the langhian and late tortonian furthermore by considering a maximum possible rotation rate of 20 ma 1 we infer that cw rotation started in sicily in langhian serravallian times between 15 16 and 11 12 ma ago the 100 cw rotation observed in pre orogenic strata from the whole of sicily is mirrored by 80 orogen scale ccw rotations characterizing the internal southern apennines palaeomagnetism therefore shows that during orogenesis the southern apennines and the sicilian maghrebides rotated in a saloon door fashion synchronous to back arc spreading of the southern tyrrhenian sea consequently our palaeomagnetic data suggest that the southern tyrrhenian back arc basin started to spread during langhian serravallian times from 15 16 to 11 12 ma significantly earlier than the late tortonian age 8 ma suggested so far by oceanic drilling data

revised dates of large earthquakes along the carrizo section of the san andreas fault california since a d 1310 30 1 precise knowledge of the age and magnitude of past earthquakes is essential for characterizing models of earthquake recurrence and key to forecasting future earthquakes we present 28 new radiocarbon analyses that refine the chronology of the last five earthquakes at the bidart fan site along the carrizo section of the south central san andreas fault which last ruptured during the fort tejon earthquake in a d 1857 the new data show that the penultimate earthquake in the carrizo plain occurred not earlier than a d 1640 and the modeled 95th percentile ranges of the three earlier earthquakes and their mean are a d 1540 1630 1585 a d 1360 1425 1393 and a d 1280 1340 1310 indicating an average time interval of 137 44 years between large earthquakes since a d 1310 30 a robust earthquake recurrence model of the carrizo section will require even more well dated earthquakes for thorough characterization however these new data imply that since a d 1310 30 the carrizo section has failed more regularly and more often than previously thought

high resolution topography derived offsets along the 1857 fort tejon earthquake rupture trace san andreas fault the great fort tejon earthquake of 1857 with an 350 km long surface rupture was the most recent major earthquake along the south central san andreas fault saf prior reconstruction of its surface slip distribution and reconstruction of preceding earthquakes along the 1857 rupture trace have contributed to formulation of the characteristic earthquake cem and uniform slip models usm for earthquake recurrence that find wide application in seismic hazard assessment and earthquake forecasting we used the high resolution b4 light detection and ranging lidar topographic data set sufficient for depiction of meter scale tectonic landforms to reevaluate the distribution of surface displacement along the 1857 rupture trace we present 450 offset measurements with displacements below 60 m increasing observation density relative to previous studies by a factor of 2 our results show that the 1857 earthquake had overall an average displacement below 3 5 m with 4 6 m released along the northwestern half of the rupture its along fault slip distribution is smooth at 10 km length scales at 28 less than prior estimates assuming a 10 km rupture depth and a 30 gpa shear modulus reconstruction of pre 1857 earthquakes is impeded by an exponential decrease in observation density with increasing displacement amount offset observation density soon reaches a level where only tentative and nonunique reconstructions are permitted the results of this study question prior surface slipreconstructions of pre 1857 rupture s that were based on a distinctly lower number of offset observations challenging the applicability of the aforementioned earthquake recurrence models to explain saf rupture behavior online material catalog of offset measurements along the 1857 surface rupture trace as well as an annotated map 1 embed inline graphic 1 gif

the late pleistocene belotinac section southern serbia at the southern limit of the european loess belt environmental and climate reconstruction using grain size and stable c and n isotopes the belotinac loess section is one of the southernmost loess paleosol environmental archives for the late quaternary in serbia the climate at this site is intermediate between the continental and the mediterranean realms which makes this loess archive potentially highly sensitive to past climatic changes this paper presents new insights into the paleoenvironmental history during the last glacial period in southern serbia using grain size and isotope proxy data the grain size parameters from the belotinac section reveal variations in the paleowind dynamics and weathering intensity and suggest the nearby valley of the ju na morava river as an important source of aeolian sediments in this area based on a multiproxy dataset alternating phases of weak interstadials and phases of enhanced loess deposition at this site were identified nitrogen isotope data suggest that during marine isotope stage 3 ecosystems of high biomass productivity and rather open n cycles prevailed during marine isotope stage 2 productivity was reduced and the n cycle was more strongly closed probably due to a shorter growing season and more pronounced temperature decline carbon isotope data indicate a possible contribution of c4 plants to the holocene vegetation but not to the glacial and interstadial ecosystems of the late pleistocene changes in atmospheric co2 level are not reflected in the carbon isotope record these findings are discussed in the light of paleoclimate proxy datasets from the morava river valley and carpathian basin as well as through comparison of carbon isotope records from loess sections in se central europe and in the rhine valley two different loess provinces exist in terms of glacial interglacial humidity changes a province of glacial drying and a province of glacial humidification the first includes loess sites under more oceanic influence where loess 13c records indicate humid interglacials and interstadials and relatively drier glacial periods the second includes the loess sites of the carpathian basin and especially the southern serbian loess area of belotinac where loess 13c records indicate more intensive aridity during interglacials but a reduced soil moisture deficit and a more humid climate due to lower evapotranspiration in interstadials and even more in glacial periods

hydrothermal frictional strengths of rock and mineral samples relevant to the creeping section of the san andreas fault abstract we compare frictional strengths in the temperature range 25 250 c of fault gouge from safod cdz and sdz with quartzofeldspathic wall rocks typical of the central creeping section of the san andreas fault great valley sequence and franciscan complex the great valley and franciscan samples have coefficients of friction 0 35 at all experimental conditions strength is unchanged between 25 and 150 c but increases at higher temperatures exceeding 0 50 at 250 c both samples are velocity strengthening at room temperature but show velocity weakening behavior beginning at 150 c and stick slip motion at 250 c these rocks therefore have the potential for unstable seismic slip at depth the cdz gouge with a high saponite content is weak 0 09 0 17 and velocity strengthening in all experiments and decreases at temperatures above 150 c behavior of the sdz is intermediate between the cdz and wall rocks

geochemical characterization and origin of southeastern and eastern european loesses serbia romania ukraine abstract the loess paleosol sections of batajnica stari slankamen serbia mircea voda romania and stary kaydaky ukraine were geochemically characterized based on discriminant analysis of major and trace elements the ratios of al ti fe ti and al fe the a cn k ternary plot and element enrichment depletion relative to the average composition of the upper continental crust the origin of the loess material in the southern pannonian basin vojvodina the lower danube basin dobrudja and the dnieper area was evaluated by comparison with the representative element composition of possible source areas and by considering the geomorphodynamic setting also the background values of the initial magnetic susceptibility of the loesses were taken into account for the lower danube basin dobrudja and the ukraine paleowind direction was reconstructed based on the geographic distribution of sandy soil texture and dunes related to river systems finally loesses were evaluated as possible samples of the average upper continental crust our results show that danube and dnieper loess areas can be clearly distinguished the former reveal higher al and fe contents the latter higher si zr hf content and indications of effective mineral and grain size sorting we can confirm that vojvodina loess originated from danube alluvial material and loess of the dnieper area from glaciofluvial sediments of the fennoscandinavian ice sheet the dobrudja loess derived also predominantly from danube alluvium but shows significant contribution of a second loess source probably the glaciofluvial sediments of the ukraine this was forced by northerly katabatic winds from the fennoscandinavian ice sheet whereas wnw winds prevailed in the western walachian plain the studied loesses reflect the average composition of the upper continental crust yet biases exist due to selective mineral element enrichment and depletion in the course of previous sedimentary recycling phases respectively material of all studied loess deposits seems to derive originally from sedimentary rocks

mesozoic volcanics of western sicily the mesozoic lavas and minor intrusions in the thrust sheets of western sicily have the following characteristics 1 the lavas in the triassic mufara formation in the north were broken into fragments which rotated independently within the incompetent strata that enclose them this behavior is characteristic of igneous rocks found within the more internal northerly thrust units 2 the jurassic lavas in the more external southerly units have consistent directions which agree with those of the ammonitico rosso limestones in the same zone and lie about 30 clockwise from those of coeval autochthonous formations in tunisia schult s presumed cretaceous directions from custonaci on the north coast similar to those found in the cretaceous scaglia rossa at terrasini to the east bychannel et al 1980 are rotated still more 140 with respect to those of the autochthonous iblean platform of se sicily these differences are believed to reflect rotation of the thrust sheets during tectonic transport in cenozoic times the internal units being the most strongly rotated 3 all the igneous rocks are highly altered generally the original mineralogy cannot be completely determined relative abundances of some of the less mobile elements ti sr y suggest that they are intraplate basalts

stream channel offset and late holocene slip rate of the san andreas fault at the van matre ranch site carrizo plain california sets of well preserved channels offset across the san andreas fault saf at the van matre ranch vmr site in the northwestern elkhorn hills area of the carrizo plain offer the opportunity to measure slip rate and examine geomorphic development of the channels the fault zone and offset channels were exposed by excavation in one fault perpendicular and five fault parallel trenches the geomor phology and stratigraphy in the channels reveal a record of filling by fluvial sedi mentation lateral colluviation and pedogenesis the buried thalweg of the currently active channel is offset 24 8 1 m while the geomorphic channel is offset approx imately 27 6 1 m seventeen samples were collected from channel margin deposits for 14 c dating an oxcal model of the radiocarbon dates with stratigraphic control suggests that the oldest date for channel incision was a d 1160 minimum and maximum slip rates ranging from 29 3 to 35 6 mm yr are derived from different assumptions about the timing of channel incision and offset the resulting slip rates at vmr agree well with the late holocene slip rate of 33 9 2 9 mm yr at wallace creek approximately 18 km to the northwest and imply that within measurement uncertainty the 30 37 mm yr velocity gradient across the saf from decadal time scale geodetic measurements is accommodated across the several meter wide saf zone at vmr over the last millennium

uncharacteristic earthquakes on the san andreas fault one model of earthquake recurrence holds that large quakes exhibit regular or characteristic rupture patterns combined with a simple picture of how elastic strain accumulates in the faults this implies that characteristic earthquakes occur at regular intervals in her perspective grant proposes that recent data from study sites along the san andreas fault are difficult to understand with this model the earthquake activity is more irregular and more clustered than the model would suggest

the belotinac section southern serbia at the southern limit of the european loess belt initial results abstract the palaeoclimate record preserved in loess deposits in s serbia is poorly understood this is in strong contrast to the situation in the north of the country vojvodina region where similar deposits have been intensively investigated in recent years this study presents a first detailed description initial proxy analysis magnetic susceptibility colour total organic carbon and preliminary luminescence chronology of a loess palaeosol sequence that is exposed in an abandoned quarry at belotinac near the city of nis s serbia the sequence is about 10 m thick and preserves three loess units and three weakly developed palaeosol units although its potential remains to be fully tapped the preliminary results demonstrate that the sequence offers a unique record of climate and environmental change during the late pleistocene at the transition between mediterranean and continental europe

roles of sorting and chemical weathering in the geochemistry and magnetic susceptibility of xiashu loess east china abstract uncertainties in paleoenvironmental interpretations for traditional chemical analysis of bulk samples result from different grain size sub populations of sediments containing variable distributions of elements and minerals therefore it is important to understand the elemental and mineral distribution in different grain sizes in determining the quantitative relationship between chemical weathering and climatic change we sieved a series of xiashu loess samples into three sub populations of different grain sizes 45 m respectively and then analyzed each population for rubidium rb strontium sr rare earth elements and magnetic susceptibility in comparison with elemental concentrations of bulk samples clay mineralogy and illitic crystallinity our results show that distinct elemental distributions and magnetic susceptibilities for different grain size sub populations are controlled by sorting and or chemical weathering although we also suggest that the xiashu loess may have the same provenance as the central chinese loess maximum concentrations of rb and fine grained magnetic minerals in the less than 2 m sub population coupled with our finding of maximum sr in the larger than 45 m fraction indicate that sr was lost during chemical weathering grain size sub population analysis is therefore an effective method for extracting paleoenvironmental information because individual sub populations show minimal variations in initial rb sr ratios compared to bulk analysis of all sizes together furthermore a negative correlation between rb sr ratios and sr concentrations for the r 2 0 97 may indicate that clay is a sensitive indicator of intensity of chemical weathering and is an ideal sub population for determining rb sr ratios but not for magnetic susceptibility

century long average time intervals between earthquake ruptures of the san andreas fault in the carrizo plain california paleoseismological data constrain the age location and associated magnitude of past surface rupturing earthquakes these are critical parameters for developing and testing fault behavior models and characterizing seismic hazard we present new earthquake evidence and radiocarbon analyses that refi ne the chronology of the six most recent earthquakes that ruptured the south central san andreas fault in the carrizo plain california united states at the bidart fan site modeled 95 percentile ranges of the earthquakes prior to the a d 1857 earthquake are a d 1631 1823 1580 1640 1510 1612 1450 1475 and 1360 1452 the average time interval between the last six earthquakes that ruptured the san andreas fault in the carrizo plain is 88 41 yr this is less than the time since the most recent a d 1857 earthquake less than all reported average intervals of prehistoric earthquakes along the entire san andreas fault and signifi cantly shorter than the 235 yr average used in recent seismic hazard evaluations the new chronological data combined with recent slip studies imply that the magnitudes of the earthquakes that ruptured the southern san andreas fault in the carrizo plain since ca a d 1360 were variable and suggest that the widely held view of rare but great surface rupturing earthquakes along this portion of the southern san andreas fault should be reevaluated 118

middle and late pleistocene loess sequences at batajnica vojvodina serbia abstract loess sequences in the vojvodina region northern serbia reveal a continuous record of paleoclimatic variations during the middle and late pleistocene the most detailed stratigraphic information comes from remarkable exposures on the cliffs of the right danube bank from vukovar to belgrade the batajnica loess section has been recognized as one of the most complete middle and late pleistocene records in this region a more than 40 m thick loess paleosol succession represents environmental transition from relative thin loess layers and rubified soils in lower part of profile to thick loess and fossil chernozems characterizing the last three glacial interglacial cycles the proposed stratigraphic model is based on a detailed magnetic susceptibility ms record which is related to the deep sea isotope stratigraphy and on correlation with other eurasian loess records using the distinct ms pattern of selected loess paleosol couplets this new stratigraphic model suggests serious revision of previous chronological interpretations ms as function of depth shows a well known pattern of low values in loess and high values in paleosols indicating strong enhancement of magnetic minerals during soil formation with the exception of the recent soil v s0 which is strongly contaminated by archaeological artifacts the third paleosol v s3 reveals the highest values in ms and a very distinct double peak the rock magnetic signal at batajnica resembles the typical pattern of the enviromagnetic records determined from other eurasian loess sites the paleopedological interpretations rubification index values and rock magnetic record at batajnica yield valuable data for the reconstruction of paleoclimatic fluctuations for the last 5 glacial interglacial cycles at least moreover the record provides an important link between the classical central european loess sites and the central asian and chinese loess provinces

slip along the san andreas fault associated with the great 1857 earthquake historical records indicate that several meters of lateral slip along the san andreas fault accompanied the great 1857 earthquake in central and southern california these records together with dendrochronological evidence suggest that the rupture occurred along 360 to 400 km of the fault including several tens of kilometers of the currently creeping reach in central california geomorphic expressions of late holocene right lateral offsets are abundant along the 1857 rupture along 300 kilometers of the 1857 rupture between cholame and wrightwood the youngest discernible offset ranges from 3 to 9 1 2 meters dormancy of the fault since 1857 almost certainly indicates that this latest offset was created in 1857 fault slip apparently associated with the 1857 earthquake varies in a broadly systematic way along the trace of the fault it is relatively uniform along each of several long segments but changes rather abruptly in value between these segments this nonuniform displacement pattern may imply that some segments of the fault rupture more frequently or experience a slower long term slip rate than others the 1857 offsets indicate a seismic moment m o between 5 3 and 8 7 10 27 dyne cm assuming a 10 to 15 km depth of rupture and relatively uniform slip as a function of depth a comparison with the rupture length average slip value and tectonic setting of the california earthquake of 1906 m s 8 1 4 indicates a value of m 8 1 4 for the 1857 event

high resolution interseismic velocity data along the san andreas fault from gps and insar 1 we compared four interseismic velocity models of the san andreas fault based on gps observations the standard deviations of the predicted secular velocity from the four models are larger north of the san francisco bay area near the creeping segment in central california and along the san jacinto fault and the east california shear zone in southern california a coherence spectrum analysis of the secular velocity fields indicates relatively high correlation among the four models at longer wavelengths 15 40 km with lower correlation at shorter wavelengths to improve the short wavelength accuracy of the interseismic velocity model we integrated interferometric synthetic aperture radar insar observations initially from advanced land observing satellite alos ascending data spanning from the middle of 2006 to the end of 2010 totaling more than 1100 interferograms with gps observations using a sum remove filter restore approach the final insar line of sight data match the point gps observations with a mean absolute deviation of 1 5 mm yr we systematically evaluated the fault creep rates along major faults of the san andreas fault and compared them with creepmeters and alignment array data compiled in uniform california earthquake rupture forecast version 2 ucerf2 moreover this insar line of sight dataset can constrain rapid velocity gradients near the faults which are critical for understanding the along strike variations in stress accumulation rate and associated earthquake hazard

an introduction to the middle and upper pleistocene loess paleosol sequence at ruma brickyard vojvodina serbia abstract six loess units and five paleosols are preserved in the 20 m thick exposure of middle and late pleistocene sediments at ruma brickyard vojvodina serbia amino acid geochronology provides stratigraphic correlations between loess paleosol units sl l1 s1 sl l2 s2 sl l3 s3 and sl l4 at ruma with loess of glacial cycles b c and d and e respectively at other central and southeastern european localities the profile represents one of the best potential sections in the region for reconstructing detailed paleoclimates and paleoenvironments of the last ca 350 000 yr initial sedimentological magnetic and malacological evidence indicate many episodes of drier conditions in the region than in other parts of central and southeastern europe during the later part of the middle and late pleistocene

latest pleistocene and holocene slip rate for the san bernardino strand of the san andreas fault plunge creek southern california implications for strain partitioning within the southern san andreas fault system for the last 35 k y an alluvial succession on the northeast side of the san bernardino strand of the san andreas fault includes distinctive aggradational and degradational features that can be matched with correlative features on the southwest side of the fault key among these are 1 a terrace riser on the northeast side of the fault that correlates with an offset channel wall on the southwest side of the fault and forms a basis for slip estimates for the period ca 35 ka to the present and 2 a small alluvial fan on the southwest side of the fault that has been matched with its most likely source gullies on the northeast side of the fault and forms a basis for slip estimates for the last 10 5 k y slip rate estimates for these two separate intervals are nearly identical the rate for the older feature is most likely between 8 3 and 14 5 mm yr with a 95 confidence interval of 7 0 15 7 mm yr the rate for the younger feature is most likely between 6 8 and 16 3 mm yr with a 95 confidence interval of 6 3 18 5 mm yr these rates are only half the previously published slip rate for the san andreas fault 35 km to the northwest in cajon pass a rate that traditionally is extrapolated southeastward along the san bernardino section of the fault results from plunge creek suggest that about half of the 25 mm yr rate at cajon pass transfers southeastward to the san jacinto fault as proposed by other workers on the basis of regional geologic relations these results indicate that the discrepancy between latest quaternary slip rates and present day rates of strain accumulation across the san bernardino section of the san andreas fault from geodesy can be largely explained by slip transfer between faults leading to spatial variation in rate along the san andreas fault nonetheless the latest pleistocene and holocene slip rate at plunge creek is still somewhat faster than rates inferred for the san bernardino section of the san andreas fault based on elastic block modeling of geodetic data and may be more appropriate than those rates for hazard estimation

iron mineralogical proxies and quaternary climate change in se european loess paleosol sequences abstract the loess paleosol sequences batajnica stari slankamen serbia and mircea voda romania represent key archives for the climate and landscape development of the middle and lower danube basin during the last 700 000 years for deciphering the quaternary climate evolution in these regions the batajnica stari slankamen and mircea voda sites are for the first time studied by a multi proxy approach based on iron mineralogical parameters changes in the iron mineralogical composition are identified and characterized by rock magnetic investigations diffuse reflectance spectroscopy drs and munsell color based proxies the results show that environmental conditions during mid and early middle pleistocene interglacials were more favorable for hematite formation suggesting a more oxidizing pedoclimate as in the more recent interglacials this is also reflected in a gradual increase of the anhysteretic remanent magnetization vs saturation isothermal remanent magnetization arm sirm ratio in the studied profiles changes in this ratio can be linked to a preferential hematitization of coarse grained ferrimagnetica and relates to warmer climate conditions and a more extended estival dry period at the same time rock magnetic parameters indicate a preferential destruction of fine grained magnetic particles in older paleosols resulting from seasonal excess moisture a progressive cooling and decrease of rainfall during the middle and late pleistocene is evidenced not only for interglacial pedocomplexes but also for glacial loess layers this finding is in line with previously published proxy records of silicate weathering and clay formation at these sites and similar trends reported from other sites in the european steppe belt relating iron mineralogical proxies to paleopedological characteristics and proxies of silicate weathering additionally a change in the seasonal pattern of the interglacial temperature and precipitation regime from a mediterranean type to a steppe type climate is revealed highlighting the potential of such a multi proxy approach possible triggers for this paleoenvironmental evolution are discussed as well finally highlighting a quaternary uplift hypothesis which best could explain the inferred trend of cooling aridification and increasing continentality accordingly changes in atmospheric circulation and rain shadow effects induced by small scale uplift of european mountain belts alps carpathians dinaric alps would provide a driving mechanism for the westward extension of the eurasian steppe belt into central and se europe during the quaternary

pedology and mineralogy of loess profiles at kapela batajnica and stalac serbia abstract profiles with multiple paleosols developed in loess at kapela batajnica and stalac were studied by chemical physical and mineralogical methods to determine paleoclimatic changes through the pleistocene the cyclic nature of sedimentary and pedogenetic processes is indicated by the caco 3 content and silt and clay mineralogy stalac is 200 km south of kapela batajnica and differences between individual paleosols at the two sites are attributed to local differences in soil parent material composition weathering intensity or erosion of the paleosols the profile at stalac provides an important link between typical middle european and se european loess paleosol sequences and indicates the relative influences of the mediterranean and continental climates statistical analysis of values for the hydrolytic alteration index of thorez and other mineral ratios calculated at 0 5 m vertical intervals suggests a steady decrease in interglacial weathering rates since the gunz mindel pedocomplexes f8 and f9 and a gradual change from warm humid to temperate dry conditions the climatic curve for the kapela batajnica sequence suggests continental conditions and correlates well with the nw european climatic curve up to the gunz mindel interglacial pedocomplex f8 the curve for the lower part of the stalac sequence shows a stronger mediterranean influence and correlates well with the curve for greece but the upper part of the stalac sequence above the riss 1 riss 2 pedocomplex f6 shows an increased continental climatic influence

a critical reevaluation of palaeoclimate proxy records from loess in the carpathian basin abstract in the carpathian basin loess is the most important archive of quaternary palaeoclimate evolution but only in the past two decades systematic and high resolution investigations were conducted those studies remarkably improved our knowledge of the regional past environmental change palaeoclimate inferences based on the magnetic susceptibility and grain size distribution as the most commonly used palaeoenvironmental proxies for the carpathian basin loess indicate colder and drier climatic conditions during glacials when compared to interglacials with an increasing number of studies using novel proxies in loess research such a traditional understanding of dry and cold glacials and humid and warm interglacials in the carpathian basin has been questioned as an illustrative example mollusc based climate reconstructions suggest generally warm and very dry summer conditions with mean july temperatures up to 21 c for the southern carpathian basin during the last glacial results based on stable carbon isotopes strongly oppose such high summer temperatures but studies based on n alkanes are in general agreement with the mollusc data when it comes to the vegetation reconstruction indicating mostly steppic conditions however n alkanes studies contradict warm and dry glacial conditions as indicated by mollusc based reconstructions pointing instead to cold and relatively humid glacials in addition there is an ongoing debate whether or not millennial scale climatic oscillations can be observed in the carpathian basin loess as well as whether this area was an important northern hemisphere dust source or rather a sink of far distance dust transport consequently the current state of the art of the palaeoclimate reconstructions from loess in the carpathian basin is rather inconsistent in order to make sense of the existing palaeoclimate data from the carpathian basin loess we have reevaluated and reinterpreted the available data we discuss and propose a coherent interpretation of rock magnetic grain size malacological stable carbon and nitrogen isotope n alkane and bacterial membrane lipid data for the last glacial cycle loess archives from the carpathian basin we show that glacial conditions in the carpathian basin led to a notable increasing north south gradient in temperature and an even stronger expressed decreasing trend in humidity and that most of the biomarker proxy data conducted in loess for the very dry southern part of the carpathian basin show a strong bias towards arid conditions in particular palaeotemperature reconstructions seem to be misleading glacial conditions were drier and colder than previously proposed summer temperatures likely under 15 c during glacials but notably warmer than in other parts of western central and eastern europe the vegetation consisted mostly of steppic environments during both glacials and interglacials we indicate that the carpathian basin has a potential to be a major dust source of the northern hemisphere during glacials although it was at the same time exposed to the deposition of fine far distance travelled dust moreover the main issues in the regional and continental correlation of loess are highlighted as well as the sensitivity of the carpathian basin loess to the millennial scale climate variability recorded in other northern hemisphere records finally we suggest that the onset of loess formation in the investigated area occurred during the middle pleistocene transition and it was probably related to intensive silt production related to glacier dynamics in the alpine ice cap

six similar sequential ruptures of the san andreas fault carrizo plain california we document the precise sizes but not the dates of the six latest offsets across the san andreas fault at wallace creek california three and perhaps four of these including the latest in 1857 show dextral offset of 7 5 8 m the third and fourth offsets however are just 1 4 and 5 2 m the predominance of similar offsets for the latest six events suggests that the fundamental properties of the fault system that control slip size do not vary greatly from event to event the large offsets imply that ruptures involving this site are typically more than 200 km long

mineral composition vs soil forming processes in loess soils a case study from krakow southern poland abstract the mineral composition of soil parent material has a clear impact on soil formation soil properties especially chemical properties and mineral transformation in soil environment despite many studies concerning loess soils detailed quantitative studies on the mineral composition and transformation of clay minerals in loess soils formed during holocene and the influence of the mineral composition of parent material on the properties of loess soils are rare the main aims of the present study were 1 to determine the influence of loess mineral composition on soil genesis and 2 to determine layer silicate transformations and clay mineral formation in loess soils in relation to soil forming processes using qualitative and quantitative x ray diffraction analyses xrd and qxrd the obtained results show that the occurrence of carbonate minerals i e calcite and their influence on chemical properties of soil play a crucial role in the evolution of loess soils in loess that does not contain carbonates dispersion and translocation of clay particles including clay minerals down the profile occur this leads to the formation of luvisols and albeluvisols in carbonate loess clay minerals and soil organic matter form stable humus mineral complexes leading to the accumulation of humus and the formation of chernozems the transformation of mica and or smectite and or vermiculite to hydroxy interlayered minerals hims is the dominant process in the studied loess soils developed in a temperate climate because intense weathering of layer silicates is possible after removal of carbonates from soil profile this indicates that the occurrence of carbonates which maintain soil ph on a level of about 7 or higher is most likely the main factor controlling the rate of weathering of layer silicates in a loess soil environment in carbonate loess the dissolution and leaching of carbonates prevail over the weathering of silicates it is highly likely that the continuous leaching of carbonates assuming that the climate will not change will lead to more intense weathering of layer silicates

paleoseismic evidence of clustered earthquakes on the san andreas fault in the carrizo plain california exposures we have excavated across the san andreas fault contradict the hypothesis that part of the fault in the carrizo plain is unusually strong and experiences relatively infrequent rupture the exposures record evidence of at least seven surface rupturing earthquakes which have been approximately dated by accelerated mass spectrometry radiocarbon analysis of detrital charcoal and buried in situ plants five large earthquakes have occurred since 1218 a d the most recent earthquake event a was the 1857 fort tejon earthquake which we have associated with 6 6 10 m of dextral slip along the main fault trace the penultimate earthquake event b most likely occurred within the period a d 1405 1510 slip from either events b and c combined or from event b alone totals 7 11 m three earthquakes events c d and e occurred in a temporal cluster prior to event b and after approximately a d 1218 the average recurrence interval within this cluster is 73 116 years depending on assumptions events f and g occurred after 200 years b c a depositional hiatus between events e and f may hide evidence of additional earthquakes events b and d within the carrizo cluster of a d 1218 1510 may correlate with events t a d 1329 1363 and v a d 1465 1495 at pallett creek on the mojave segment of the fault this suggests two fault ruptures similar in length to that of 1857 events c and e apparently did not rupture the mojave section which suggests that the carrizo segment has ruptured independently or in combination with segments to the north irregular repeat times of large earthquakes suggest a pattern of clustered events at the end of seismic supercycles

reassessment of a slip budget along the parkfield segment of the san andreas fault historically the parkfield segment has represented a transition in fault behavior along the san andreas fault saf despite a 33 mm yr long term slip rate along the saf slip has not been observed on the cholame segment since the great 1857 fort tejon earthquake during that time the parkfield segment has experienced slip from at least six m 6 0 earthquakes aseismic fault creep and from minor earthquakes data from aseismic slip rate studies and historical earthquake studies allow us to estimate the total slip released along this portion of the saf since 1857 assuming the saf should slip at the long term slip rate a slip deficit of 5 m exists along the cholame segment since 1857 the slip deficit is approximately equivalent to 1857 offsets measured on the cholame and the southeast portion of the parkfield segment thus the slip deficit in southeast parkfield and cholame may be as great as the slip accommodated along these segments in 1857 the slip deficit abruptly decreases to the northwest across the parkfield segment it is 2 m near the town of parkfield and 0 m northwest of middle mountain an m 7 event rupturing all or part of the cholame segment and the southeastern parkfield segment slip decreasing to the northwest would release the accumulated slip and is plausible importantly this study also shows that the change in the pattern of strain release occurs in the middle of the parkfield segment rather than at its ends online material tables showing aseismic and coseismic slip estimations and calculations

present tectonic motion across the coast ranges and san andreas fault system in central california geodetic results from very long baseline interferometry vlbi satellite laser ranging slr and the global positioning system gps are used to estimate angular velocities between the sierran microplate pacific plate and north american plate the sierra pacific pole of rotation lies nearer to the san andreas fault than does the pacific north america pole of rotation and leads to different tectonic implications than if the latter is used the angular velocities show that the san andreas fault system and central california coast ranges accommodate motion of 39 2 mm yr mainly by strike slip faulting all confidence limits following signs in this paper are 95 confidence limits fault normal motion is small is mainly convergent at rates up to 3 3 1 0 mm yr and varies along the coast but is divergent at 2 6 1 2 mm yr across san pablo bay and associated topographic lows across which the sierran and central valley watershed drains to the pacific ocean the mountain ranges tend to be larger where the fault normal convergence rates are larger the low convergence rate 0 5 1 8 mm yr normal to the san andreas fault in the carrizo plain differs sharply from that previously inferred 8 2 1 2 mm yr and 4 9 1 6 mm yr by feigl et al 1993 the difference is due to differences between their and our elastic strain accumulation models and between how their and our pacific plate reference frames are defined the ranges in most places require a minimum of 4 2 1 m y of fault normal convergence at the present rate to attain their present cross sectional area if erosion is neglected more if it is not the amount of convergence previously estimated from a balanced cross section across the diablo range in central california requires 10 8 3 m y of convergence at the present rate the former is consistent with widely held views about the onset of the coast range orogeny but the latter is not both are consistent however with the recent plate reconstructions by s cande j stock and colleagues which indicate that pacific plate motion relative to north america changed to a more convergent direction 20 25 clockwise of its prior direction at ca 8 to 6 ma and not at 3 5 ma as had been previously inferred the inferred change in direction of plate motion is large compared with the present angle of convergence across the straight and narrow segment of the san andreas fault of 0 7 4 7 from which we infer that the sierran microplate changed motion relative to north america at the same time ca 8 to 6 ma as did the pacific plate we further infer that the motion accommodated across the great basin must also have changed at the same time we also examine the hypothesis that stable sliding occurs along the san andreas fault and other northwest striking strike slip faults in central california where the fault normal convergence rate is low or negative and that these faults are unstable where the fault normal convergence rate is high such a relationship appears to hold in general but fails in detail in particular there are substantial sections of fault with small inferred rates of fault normal convergence across which the san andreas fault is locked moreover the creeping section of the san andreas fault i e the section between parkfield and the calaveras junction is the locus of greater fault normal convergence 3 2 1 4 mm yr than is the locked part of the fault 0 5 1 8 mm yr south of parkfield thus this hypothesis is at best a partial explanation for the observed distribution of locked and nonlocked sections of the fault

slip rates and off fault deformation in southern california inferred from gps data and models 1 in southern california fault slip rate estimates along the san andreas fault saf and garlock fault from geodetically constrained kinematic models are systematically at the low end or lower than geologic slip rate estimates the sum of geodetic model slip rates across the eastern california shear zone is higher than the geologic sum however the ranges of reported model and geologic slip rate estimates in the literature are sufficiently large that it remains unclear whether these apparent discrepancies are real or attributable to epistemic uncertainties in the two types of estimates we further examine uncertainties in geodetically derived slip rate estimates on major faults in southern california by conducting a suite of inversions with four kinematic models long term rigid elastic block models constrained by the geologic slip rates cannot fit the present day gps derived velocity field deforming permanent off fault strain elastic block models and viscoelastic earthquake cycle block models constrained by geologic slip rates can fit the present day gps derived velocity field with 28 33 of the total geodetic moment rate occurring as distributed deformation off of the major faults models incorporating viscoelastic mantle flow predict systematically higher slip rates than purely elastic models on many of the major southern california faults with ranges of elastic viscoelastic 29 34 30 37 mm yr for the carrizo saf segment 20 24 20 32 mm yr for the mojave saf segment 14 17 18 22 mm yr for the coachella saf segment 13 19 14 22 mm yr for the san jacinto fault and 5 11 5 11 mm yr for the western garlock fault

the velocity field along the san andreas fault in central and southern california the velocity field within a 100 km broad zone centered on the san andreas fault between the mexican border and san francisco bay has been inferred from repeated surveys of trilateration networks in the 1973 1989 interval the velocity field has the appearance of a shear flow that remains parallel to the local strike of the fault even through such major deflections as the big bend of the san andreas fault in the transverse ranges of southern california across strike profiles of the fault parallel component of velocity exhibit the expected sigmoidal shape whereas across strike profiles of the fault normal component of velocity are flat and featureless no significant convergence upon the fault is observed even along the big bend sector of the fault simple dislocation models can explain most of the features of the observed velocity field but those explanations are not unique about 35 mm yr of relative plate motion is accounted for within the span of the trilateration networks geologic studies indicate that the secular slip rate on the san andreas fault is about 35 mm yr the agreement between these two estimates implies that most of the strain accumulation is elastic and will be recovered in subsequent earthquakes the relative motion observed across the san andreas fault 35 mm yr plus that observed across the eastern california shear zone 8 mm yr accounts for most 43 mm yr of the observed north america pacific relative plate motion 47 mm yr