global positioning system measurements of present day crustal movements in the arabia africa eurasia plate collision zone we present and interpret global positioning system gps measurements of crustal motions for the period 1988 1994 at 54 sites extending east west from the caucasus mountains of southern russia georgia and armenia to the aegean coast of turkey and north south from the southern edge of the eurasian plate pontus block to the northern edge of the arabian platform viewed from a eurasia fixed reference frame sites on the northern arabian platform move n38 13 w at 20 3 mm yr roughly consistent with the velocity implied by nuvel 1a circuit closure n23 7 w at 24 2 mm yr the motion of arabia appears to be transferred directly to the region of turkey north of the suture however eastern turkey is characterized by distributed deformation while central western turkey is characterized by coherent plate motion involving westward displacement and counterclockwise rotation of the anatolian plate internal deformation within the central part of the anatolian plate is less than 2 mm yr the anatolian plate is decoupled from eurasia along the right lateral strike slip north anatolian fault naf this different response in eastern and western turkey to the collision of arabia may result from the different boundary conditions the hellenic arc forming a free boundary to the west and the asian continent and oceanic lithosphere of the black and caspian seas forming a resistant boundary to the north and east we derive a best fitting euler vector for anatolia eurasia motion of 29 2 0 8 n 32 9 0 4 1 3 0 1 m y the mapped surface trace of the naf corresponds well to a small circle about this pole the new euler vector implies an upper bound for naf slip rate of 30 2 mm yr i e assuming all relative motion is accommodated along the naf using the nuvel 1a euler vector for arabia eurasia and the gps euler vector for anatolia eurasia we determine an arabia anatolia euler vector of 31 2 n 45 2 e 0 9 0 1 m y and an upper bound on the east anatolian fault slip rate of 15 3 mm yr the aegean trough region of western turkey deviates significantly from coherent plate rotation in addition to rotating with anatolia this region shows roughly n s extension at a rate of 14 5 mm yr taken together with satellite laser ranging results along the hellenic arc the contemporary pattern of deformation indicates increasing motions toward the arc suggesting that the westward displacement and counterclockwise rotation of anatolia is driven both by pushing from the arabian plate and by pulling or basal drag associated with the foundering african plate along the hellenic subduction zone

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

the surface rupture and slip distribution of the 17 august 1999 izmit earthquake m 7 4 north anatolian fault the 17 august 1999 izmit earthquake occurred on the northern strand of the north anatolian fault zone the earthquake is associated with a 145 km long surface rupture that extends from southwest of duzce in the east to west of hersek delta in the west detailed mapping of the surface rupture shows that it consists of five segments separated by releasing step overs herein named the hersek karamursel golcuk izmit sapanca lake sapanca akyazi and karadere segments from west to east respectively the hersek segment which cuts the tip of a large delta plain in the western end of the rupture zone has an orientation of n80 the n70 80 e trending karamursel golcuk segment extends along the linear southern coasts of the izmit gulf between karamursel and golcuk and produced the 470 cm maximum displacement in golcuk the northwest southeast striking golcuk normal fault between the karamursel golcuk and izmit sapanca segments has 2 3 m maximum vertical displacement the maximum dextral offset along the izmit sapanca lake segment was measured to be about 3 5 m and its trend varies between n80 e and east west the sapanca akyazi segment trends n75 85 w and expresses a maximum displacement of 5 2 m the karadere segment trends n65 e and produced up to 1 5 m maximum displacement the karadere and sapanca akyazi segments form fan shape or splaying ruptures near their eastern ends where the displacement also diminished

holocene river and slope activity in the visoko basin bosnia herzegovina climate and land use effects alluvial and colluvial deposits were investigated at prehistoric tells close to the bosna river the chronology is based on ten radiocarbon ages five optically stimulated luminescence ages and on the archaeological record fluvial activity of the bosna river is indicated by overbank fines ca 5000 1000 bc 500 bc until today and a phase of lateral displacement of the river bed with subsequent channel fills ca 2000 500 bc early holocene fluvial activity was probably triggered by climatic variability but might have promoted the expansion of neolithic societies into the visoko basin mid to late holocene river activity occurred under increased climatic aridity but coincided with the expansion of prehistoric settlements to a wider area of the river basin on hard rocks in the adjacent mountainous areas the destruction of the thin soil cover in the mountains is discussed as a probable trigger for enduring subsequent river activity this is also indicated by a change in the geochemical signature of the alluvial sediments the proposed mechanism might explain the mid to late holocene river history in other regions the potential of geochemical analyses and diachronous high resolution archaeological records to make inferences regarding sediment sources and geomorphological processes is demonstrated copyright 2013 john wiley sons ltd

holocene landscape dynamics at the tell arslantepe malatya turkey soil erosion buried soils and settlement layers slope and river activity in a middle euphrates catchment alluvial and colluvial sequences were studied around the prehistoric tell arslantepe in 11 exposures and additional auger cores the chronology is based on 11 optically stimulated luminescence osl ages four radiocarbon ages and the embedded artifacts sediments contained wood charcoals providing information on former vegetation fluvial activity is documented during late glacial times 15 4 2 5 12 8 3 1 kyr and frequently after roman times slope and soil erosion occurred in the early 10 6 1 4 8 2 0 7 kyr and mid late holocene 6 7 0 9 5 4 0 7 4 7 0 7 2 6 0 2 2 5 0 2 1 9 0 2 1 8 0 2 kyr and during the last 1000 years the early holocene erosion phases pre date the so far established onset of settlement at the tell this either indicates an earlier onset of agricultural land use than assumed or climatic influence on erosion such as the 10 3 and 8 2 kyr climate events known from western europe the erosion phases at around 5 0 and 2 6 kyr could reflect geomorphic respon

surface rupture and slip distribution along the karadere segment of the 17 august 1999 izmit and the western section of the 12 november 1999 duzce turkey earthquakes on 17 august 1999 the mw 7 5 i zmit turkey earthquake produced surface rupture in excess of 120 km and perhaps as much as 200 km with up to 5 m of dextral slip along a western portion of the north anatolian fault zone the 12 november 1999 mw 7 1 duzce turkey earthquake produced a 40 km long sur face rupture including 9 km of rupture overlap with the eastern end of the august event our mapping focused on the 40 km long karadere rupture segment the east ernmost segment of the august event as well as on the western 20 km of the no vember rupture maximum dextral slip along the karadere segment is approximately 1 5 m and the average slip on this segment is close to 1 m although slip along the karadere segment is considerably less than that on segments to the west this segment is of particular interest for three reasons 1 the western boundary of the karadere segment is defined by the most striking structural discontinuity along the entire au gust surface rupture i e a 5 km wide zone of no surface rupture as well as a 25 change in trend from e w to ene and such a discontinuity may have important implications for rupture dynamics 2 surface rupture terminates at the east end of the karadere rupture segment at a 1 5 to 3 km wide extensional step over at eften lake and 3 the 12 november 1999 duzce earthquake reruptured the easternmost 9 km of the karadere segment raising interesting questions about rupture dynamics and interactions between events on adjacent fault segments the details of the 17 august 1999 and l2 november 1999 surface rupture traces suggest that rupture may have partially propagated across the eften lake extensional step over although this step over seems to have acted as an effective barrier to rupture propagation

surface breakage of the 1992 landers earthquake and its effects on structures abstract the landers california earthquake m w 7 3 provides an exceptional opportunity to study surface rupture of an earthquake fault detailed maps of the lateral distribution of fracturing adjacent to main traces show that rupture patterns are much more complex than documented in past studies of surface ruptures the rupture occurs in tabular zones up to hundreds of meters wide a main trace within each rupture zone accommodates much of the shear deformation but considerable fracturing occurs throughout the tabular zone the en echelon pattern of fracturing in step over zones between main traces is typically even more complex than those along major fault zones inspection of several on grade concrete slabs indicates that unreinforced concrete foundations generally crack when subjected to distinct ground ruptures beneath them or when they are twisted because of differential ground movements across broad zones methods of mitigating the potential hazards associated with earthquake fault rupture are presented

significance of transport parallel strain variations in part of the raft river shear zone raft river mountains utah usa this paper examines part of the raft river shear zone rrsz in northwestern utah that exhibits an extreme transport parallel increase in strain intensity coupled with a transition from flattening to constrictional strain detailed geologic mapping and finite strain quartz c axis fabric and kinematic vorticity analyses demonstrate local necking of the shear zone associated with an increase in transport parallel elongation accommodated by a stretching fault at the base of the shear zone the domain of intense deformation and necking of the shear zone is localized where the basal stretching fault cuts rheologically weak rocks this domain is characterized by strain in the constrictional field caused by transport perpendicular flow into the area of high transport parallel elongation where rocks cut by the stretching fault are rheologically strong the rrsz locally records flattening strain and lower strain intensities limiting the amount of stretching needed at the base of the shear zone in any one direction and or recording transport perpendicular flow into adjacent highly extended domains the rheology of rocks cut by the stretching fault directly controlled the amount and style of zone normal shortening and transport parallel elongation and these observations provide an example of deformation partitioning in a crustal scale structure driven by local rheological transitions

charcoal recognition taphonomy and uses in palaeoenvironmental analysis abstract charcoal predominantly the product of wildfires is abundant in many sedimentary rocks deposited in a wide range of environments from terrestrial to marine it also occurs in some volcanic rocks this paper outlines aspects of charcoal formation both natural and experimental and briefly considers the taphonomic processes leading to a final assemblage this is done using examples from recent fires and through experimentation the ways in which charcoal assemblages are recognized in the field and extraction in the laboratory are also considered methods of charcoal identification are presented the range of charcoalified plant organs that can be found is discussed and a wide range of study methods outlined including light microscopy dark field light microscopy reflectance microscopy scanning electron microscopy and synchrotron radiation x ray tomographic microscopy emphasis in this paper is on the study of macro and meso charcoal above180 m finally there is a consideration of the broad use of charcoal from plant evolution studies fire history studies vegetation studies anatomical studies climate and atmospheric studies and the wider importance of charcoal for the earth and biological sciences charcoal is information rich but yet is an under utilized resource

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

present day kinematics of the middle east and eastern mediterranean the middle east and eastern mediterranean regions contain three major strike slip fault zones the dead sea fault zone dsfz and the north and east anatolian fault zones nafz and eafz these accommodate northward motion of the african and arabian plates relative to eurasia and westward motion of the small turkish plate this study deduces an internally consistent solution for the present day kinematics of these plates which is accurate to better than 20 and applicable throughout time since 5 ma by constraining the slip senses and rates on these strike slip fault zones the 7 0 5 mm yr 1 left lateral slip rate on the dsfz is associated with counterclockwise rotation of arabia relative to africa at 0 33 m y 1 around an eulcr pole near 33 n 23 e the nafz takes up counterclockwise rotation of the turkish plate relative to eurasia at 0 83 m y 1 13 around a pole at 31 n 35 5 e with right lateral slip rate 15 mm yr 1 the resulting prediction for the eafz involves 14 mm yr 1 left lateral motion and 2 mm yr 1 of shortening between arabia and turkey the triple junction of africa arabia and turkey is near the city of kahramanmaras this locality contains a narrow promontory bounded by ssw trending left lateral faults at the edges of the arabian and turkish plates which is loosely attached to the african plate moving westward relative to its interior at 4 mm yr 1

gps derived strain rate field within the boundary zones of the eurasian african and arabian plates we use the gps velocity field 1988 1998 for eastern mediterranean and asia minor to determine the crustal deformation strain rate field in an area bounded by 35 n and 43 n and 20 e and 48 e we calculate the normal and shear strain rate components associated with the major faults and compare these qualitatively with seismological data uncertainties in the calculation of the strain rates reach 50 nstrain yr 1 in sparsely observed parts of anatolia whereas we estimate errors 20 nstrain yr 1 in the aegean and marmara regions the largest compressional strain rate components in the eastern part of the study area occur along the greater caucasus mountain front reaching 70 nstrain yr 1 1 nstrain yr 1 0 0317 10 15 s 1 the north anatolian fault zone is the clearest feature in the shear strain rate field it is expressed as a pronounced dextral strike slip fault zone reaching rates of up to 170 nstrain yr 1 this holds true also for the izmit area where the august 17 1999 earthquake occurred central anatolia is almost strain free whereas extension prevails in western anatolia the principal axes of extension vary around the n s direction with strain rates of up to 85 nstrain yr 1 these extensional areas coincide with graben features and normal faulting earthquakes the central and southwestern aegean sea is strain free with values far below 40 nstrain yr 1 the seismic cluster around the dodekanissa islands southeastern aegean sea coincides with nw se oriented extension attaining strain rates of up to 90 nstrain yr 1 this area of extension also exhibits recent active volcanism the entire hellenic arc shows compressional strain rates perpendicular to the arc the pliny strabo troughs along the eastern segment of the arc show left lateral shear strain rates reaching 80 nstrain yr 1 significant extension is found in central greece with a nne ssw oriented maximum of 120 nstrain yr 1 centered around the gulf of corinthos the kephalonia fault zone in nw greece is a distinct dextral fault zone separating apulia from the rapidly moving aegean microplate right lateral shear strain rates reach 150 nstrain yr 1

interdisciplinary interpretation of challenging archives charcoal assemblages in drina valley alluvial and colluvial sediments jagnilo bosnia and herzegovina in connection to an archaeological project in bosnia and herzegovina charcoal fragments from several geomorphological profiles were analysed due to the lack of other archives for palaeoenvironmental reconstruction the major aim of the presented study was to systematically test the suitability of the documented colluvial and alluvial layers for charcoal analysis the profiles uncover main phases of sedimentation of drina valley holocene alluvial sedimentation and for the first time provide anthracological data from the area giving initial insight into the vegetation of the catchment areas and into dynamics of the drina for the late holocene the presence of several genera in the catchment areas of the investigated profiles was documented the most important genera are quercus and ostrya carpinus type fagus acer and pinus are also present light demanding genera such as corylus and the maloideae group indicate human activities alluvial elements such as ulmus fraxinus and alnus are present a major advantage of this investigation is the distinction of catchment areas for alluvial and colluvial layers by the means of charcoal analysis this interdisciplinary cooperation of botanists geoscientists and archaeologists yields new information about a rarely investigated region of southeastern europe and thus improves understanding of natural processes and human impact

p ed xrf geochemical signatures of a 7300 year old linear band pottery house ditch fill at vrable ve lke lehemby slovakia house inhabitation and post depositional processes abstract over the past decades multi element analyses have become increasingly important for archaeological and geoarchaeological research in particular the recent expansion in availability of portable ed xrf p ed xrf devices has allowed for the fast acquisition of large data sets in the presented paper we evaluate the quantitative measurement capability of a p ed xrf device through comparison with wd xrf sampling drying and homogenization sieving in a case study we measured the elemental contents of the archaeo sediment sequence fill of a trench of a ca 7300 year old linear pottery house at the site of vrable ve lke lehemby in southeastern slovakia based on a model applied at the nearby bronze age settlement mound of fidvar the p content of the archaeo sediment was considered as a proxy of palaeo demography however the measured p contents were much too small to reflect the metabolism of a reasonable number of inhabitants therefore in addition to the possibilities of shorter than expected duration of house occupation and incomplete garbage deposition within the ditches the post depositional settlement history is considered in detail furthermore bio cycling by plants during different subsequent phases of holocene landscape development forested agricultural field use has not been considered extensively in interpretations of the archaeological record so far but might have had a considerable influence on the shallow buried archaeological record a reconsideration of the interpretation of the geochemical record from a nearby bronze age site fidvar is thus suggested

kinematic significance of l tectonites in the footwall of a major terrane bounding thrust fault klamath mountains california usa abstract detailed geologic mapping cross section reconstructions strain analyses and kinematic analyses enable the reconstruction of a one kilometer wide domain of l tectonites in the east west striking subhorizontal to gently south dipping pigeon point high strain zone pphsz associated with a major thrust fault separating oceanic and arc affinity terranes in the klamath mountains california l tectonites are associated with 1 a convex upward warp of the upper high strain zone boundary 2 a transition from mafic metavolcaniclastic rocks to micaceous quartzites 3 folds subparallel with mineral lineations 4 emplacement of synkinematic ultramafic mafic intrusive bodies and 5 a local temperature increase from greenschist to amphibolite facies conditions pure shear dominated deformation accommodated zone normal shortening and transport parallel elongation coupled with subordinate top to the west directed thrust style simple shear l tectonite formation was controlled by the shape of the high strain zone boundary driving lateral flow into the apex of the lens shaped zone in response to a favorable kinematic geometry and bulk strain in the constrictional field localized magmatic heating best explains the shape of the high strain zone boundary but l tectonites are not partitioned into a single rheological domain during terrane amalgamation strain path partitioning occurred with localized top to the west directed simple shear partitioned into a structurally overlying thrust zone and pure shear dominated subvertical shortening and transport parallel elongation partitioned into the pphsz

deformation during the 12 november 1999 duzce turkey earthquake from gps and insar data only 87 days after the mw 7 5 17 august 1999 izmit earthquake the duzce earthquake ruptured a ca 40 km long adjoining strand of the north anatolian fault naf system to the east we used displacements of 50 global positioning system gps sites together with interferometric synthetic aperture radar insar range change data spanning the event to estimate the geometry and slip distribution of the coseismic rupture postseismic deformation transients from the duzce earth quake and the preceding i zmit event that are included in some of the measurements are corrected for using dislocation models fit to gps data spanning the various time periods nonlinear inversions for fault geometry indicate that the rupture occurred on a ca 54 north dipping oblique normal right lateral fault distributed slip inver sions indicate maximum strike slip near the center of the duzce fault close to the earthquake hypocenter slip magnitude and depth of faulting decrease to the west and east of the hypocenter both gps and insar data suggest that normal slip is restricted to the shallow portion of the rupture the duzce earthquake had the highest slip to rupture length ratio of any historic earthquake along the naf

westward propagation of the north anatolian fault into the northern aegean timing and kinematics we present new evidence for the propagation processes of the north anatolian fault folding in the dardanelles straits region allows us to document the timing of the deformation preceding and the finite displacement after the passage of the propagating tip of the fault the accuracy of the observations is due to interplay between deformation and the sea level changes in the mediterranean the well known messinian regression followed by the pliocene transgression the long term kinematics around the sea of marmara pull apart total displacement of about 85 km over the past 5 m y is similar to the present day kinematics deduced from space geodesy at a larger scale westward propagation of the north anatolian fault over nearly 2000 km in the past 10 m y appears to be associated with strain recovery suggesting that the continental lithosphere retains long term elasticity

archaeopedology and chronostratigraphy of colluvial deposits as a proxy for regional land use history baar southwest germany abstract soils are the basis of our food production supplying plants with nutrients and water farming leaves traces in the soil because cultivation can cause soil erosion one result is the formation of colluvial deposits which can be used as geoarchives of past human impacts on their terrestrial environment the present study combines pedological and archaeological knowledge with chronostratigraphic analyses to infer deposition phases of colluvial material thereby allowing the reconstruction of past land use and settlement activities in the baar region sw germany local colluvial signals are interpreted as a regional proxy for increased soil erosion and colluviation on the baar seven main deposition phases of colluvial material can be detected by 28 luminescence dates and 41 radiocarbon ages distributed through 26 soil profiles our results indicate increased colluviation in the younger neolithic 3800 bce the early to middle bronze age 1550 bce the iron age 500 bce the roman empire 100 ce and from the high middle ages onwards 1200 ce 1300 ce 1600 ce these dates and record of colluviation complement archaeological knowledge of the fundamental impact of human activities on the landscape due to sedentism and agriculture early anthropogenic hypothesis our study shows that most periods of intensified colluvial deposition often but not always date to times with colder more humid climatic periods the spatial and temporal correlation of main depositional phases with archaeological finds points to land use as the determining factor of colluvial deposition at least since roman times

coseismic ruptures and tectonic landforms along the duzce segment of the north anatolian fault zone ms 7 1 november 1999 1 this paper presents a comparison between the pattern of surface ruptures produced by a single earthquake and patterns of cumulative deformation we performed a detailed study of the 1999 earthquake coseismic ruptures and of the long term tectonic landforms in a key area of the duzce fault segment of the north anatolian fault we observed a scale independent en echelon arrangement of the coseismic surface ruptures as a whole the long term geomorphic expression of the duzce fault near the 1999 ruptures is evidence of the principal slip zone at depth that accommodates the bulk of the displacement during an individual rupture event this may stay localized through many rupture episodes with persistent geometry and kinematics the long term tectonic and geomorphic expression of the fault in a broader area around the 1999 ruptures defines a wider deformation zone in fact an old and complex fault arrangement has been mapped partially coinciding with the 1999 rupturing fault suggesting that the 1999 ruptures are an incomplete expression of the long term duzce fault system the relationships between the coseismic and the old fault systems suggest an evolution of the fault pattern trough time with a tendency to simplify a geometric complexity into a straighter mature trace the integrated investigation of long term tectonic morphologies and structural pattern offers a noteworthy frame to interpret the coseismic rupture kinematics and clarifies their complexities moreover to fully understand the principal slip zone at depth this work shows the importance of the study of strain distribution pattern and evolution of surface rupturing faults

orogen scale l tectonite domain in the tongbai orogenic belt central china geological setting and origin abstract l tectonite is well developed and widely distributed in the tongbai orogenic belt in central china the orogenic belt as a whole has an antiformal geometry and the hinge of the antiform is subhorizontal and trends nw se the l tectonite occurs in the core of the antiform in a zone that is 10 30 km wide and over 100 km long lineations in the l tectonite are sub horizontal parallel to the hinge of the antiform sheath folds are also well developed associated with the l tectonite with the hinges parallel to the lineations migmatite occurs in the core and structurally below the l tectonite and has a gradational relationship with the l tectonite the domain of l tectonite is bounded by three ductile shear zones on the north at the top and on the south respectively well developed shear sense indicators indicate that the southern the overlying and the northern shear zones have a dextral top to nw and sinistral sense of shear respectively these geometrical and kinematic data indicate that the three shear zones are likely part of a single shear zone that wraps around the l tectonite domain the l tectonite zone in the core moves southeast relative to the hanging wall the development of the tectonite is interpreted to be a result of this special geometry and kinematics and reflects a post collisional orogen parallel extension synchronous with migmatization and the continuing convergence between the yangtze block and the north china block in the early cretaceous

holocene palaeovegetation of the tigray plateau in northern ethiopia from charcoal and stable organic carbon isotopic analyses of gully sediments abstract a long history of supporting sophisticated but unsustainable kingdoms makes the tigray plateau of the northern ethiopian highlands a promising region for the study of relationships between palaeoenvironmental change and the trajectories of human civilizations the natural vegetation above 2200 m elevation is thought to be forests dominated by juniperus procera nonetheless this hypothesis is not supported in the vegetation cover now and is scarcely studied in the palaeorecord to examine changes in vegetation climate and land use we identified buried charcoalized wood and estimated the percentage of organic carbon from c 4 plants c 4 carbon from 13 c values of bulk organic matter in the soils of gully walls in the boundaries of the ancient aksumite empire charcoal ranged in age from ca 13 700 to 110 cal yr bp juniperus procera occurred in even the youngest samples although at lower percentages of the total charcoal than in older samples nevertheless rapidly regenerating angiosperms usually dominated or co dominated charcoal even in some of the oldest strata a shift towards higher c 4 carbon and total organic carbon toc in soils younger than 3300 cal yr bp began during a period when agricultural uses of land may have increased in order to support the needs of growing societies a shift towards higher c 4 carbon but lower toc began at ca 6000 cal yr bp however during a period when no charcoal was found and no changes in human societal complexity are known these results indicate that juniper forest types have long been present at 2200 m in the tigray plateau but that they have rarely been the dominant natural vegetation furthermore lack of repeatable correspondence between factors suggests that the causes of similar shifts in vegetation composition were not always the same

the gps strain rate field in the aegean sea and western anatolia the gps velocity field of the aegean sea and western anatolia is used to determine crustal deformation strain rates for the period 1988 to 1996 the zone from the marmara sea to the north aegean trough is associated with strong right lateral shear motion with maximum strain rates of 170 nstrain a in the northern aegean sea the extensional deviatoric axes are oriented nne ssw associated with strain rates reaching 150 nstrain a and in western anatolia varying around n s with rates of up to 95 nstrain a the extensional areas mostly coincide with active graben features the south western aegean sea is almost strain free in general the areas of high geodetic strain rates are accompanied by distinct seismic clusters whereas the strain free regions are nearly aseismic

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

anthracology and taphonomy from wood gathering to charcoal analysis a review of the taphonomic processes modifying charcoal assemblages in archaeological contexts abstract a discussion on the representativeness of charcoal from archaeological contexts and their potential for palaeoecological reconstruction is presented the charcoal deposits studied are the result of human activities and natural processes difficult to separate on the basis of their effects only this is why taphonomy should not be limited to the study of charcoal after the extinction of fire as a result our questioning has been widened to include the entire succession of processes from past vegetation to the anthracological diagram we propose a review of the taphonomic processes affecting anthracological assemblages in archaeological contexts from wood gathering to the analysis of charcoal results human practices appear clearly as the first filter determining or conditioning the assemblage the combustion process can induce a double filter by limiting the taxonomic information and by falsifying the initial quantity of burned wood post depositional agents represent a third level of filters between the vegetation and the anthracological assemblage finally sampling and quantification methods can also induce a distortion of the assemblage the aim of this paper is to present the state of the discipline today the problems already solved and the questions that remain to be studied

are holocene wood charcoal fragments stratified in alpine and subalpine soils evidence from the alps based on ams 14c dates the possible stratification of charcoal particles buried in well drained soil in the subalpine and alpine belts in an inner valley of the northwestern alps savoy france is examined radiocarbon dating and quantification of charcoal fragments more than 400mm in diameter were used to analyse the soil depth distri bution of charred wood particles between 1700 and 2600 m a s l in two study areas 10 km apart in the same valley above 2100 m a s l in both study areas charcoal concentrations are low and mainly contained in the upper horizons and all dated charcoal fragments are older than 2300 cal yr bp below 2100 m the greatest charcoal concentration is located in the topmost 30 cm of the soil profiles and the 14c dates yield late holocene ages 1600 to 75 cal yr bp when profiles have an elevated charcoal concentration in deeper horizons the charcoal dates are mid holocene 6360 2770 cal yr bp radiocarbon dates of charcoal fragments do not reveal an age depth relationship although charcoal mass concentrations suggest a coarse stratification of char coal particles in the soils below 2100 m at forested sites this difference may be due to the charcoal dating on a single fragment which is not representative of the charcoal assemblage containing a few tens to thousands of fragments the lack of stratification probably results from soil bioturbation by soil fauna soil reworking by uprooted trees and freeze thaw processes at higher elevation in the alpine belt charcoal is concentrated in the topmost soil due to a low bioturbation rate from a pedological point of view the 14 c dating and the quantification of charcoal concentration per soil level provides a time range estimate for soil particle reworking by anecic earthworms dung beetles and other biota this has application in pedogenesis studies to estimate the rapidity of processes of soils dynamics these data suggest that soils in the alps have limited potential for palaeoecological studies based on a stratigraphic assumption but have more applications in precise spa tial studies

shear zones formed along long straight traces of fault zones during the 28 june 1992 landers california earthquake surface rupturing during the 28 june 1992 landers california earthquake east of los angeles accommodated right lateral offsets up to about 6 m along segments of distinct en echelon fault zones with a total length of 80 km the offsets were accommodated generally not by faults distinct slip sur faces but rather by shear zones tabular bands of localized shearing along simple stretches of fault zones at landers the rupture is characterized by telescoping of shear zones and intensification of shearing broad shear zones of mild sheafing containing narrow shear zones of more intense sheafing containing even nar rower shear zones of very intense sheafing which may contain a fault thus the ground ruptured across broad belts of shearing with clearly defined subparallel walls oriented nw each broad belt consists of a broad zone of mild sheafing extending across its entire width 50 to 200 m and much nan ower a few meters wide shear zones that accommodate most of the offset of the belt and are por trayed by en echelon tension cracks in response to right lateral shearing the slices of ground bounded by the tension cracks rotated in a clockwise sense producing left lateral sheafing and the slices were forced against the walls of the shear zone producing thrusting even narrower shear zones formed within the narrow shear zones although these probably are guides to right lateral fault segments below the surface rupturing during the earthquake is characterized not by faulting but by the formation of shear zones at various scales

rupture processes of the 1999 august 17 izmit and november 12 duzce turkey earthquakes summary we derive the rupture history of the 1999 august 17 izmit mw 7 4 and 1999 november 12 duzce mw 7 1 earthquakes in turkey from teleseismic body waves using broad band data of the global seismograph network aftershock locations and mapped surface breaks the centroid solutions indicate strike slip mechanisms for both events the izmit earthquake was characterized by rupture propagating predominantly eastwards it consisted of a main rupture lasting about 25 s followed within 1 min by two more events of mw 6 9 and mw 7 0 with the teleseismic data we could not resolve the westward extent of rupture into the marmara sea however an upper bound of the seismic moment release west of the epicentre of the izmit event is estimated to be 1 9 1019 n m the duzce earthquake lasted about 14 s and was characterized by a bilateral mode of rupture in excellent agreement with mapped surface breaks and aftershock locations

a review of charcoal analysis as a tool for assessing quaternary and tertiary environments achievements and limits abstract identification of charcoal fragments 2 mm using reflected light microscopy is routinely carried out to study former natural ecosystems assess changes in vegetation communities over time and identify the influence and patterns of behaviour of human populations on vegetation material studied comes either from archaeological horizons or soil profiles despite undeniable limits informative results have been obtained in the last 25 years mostly in southwestern europe where charcoal analysis has been widely applied in quaternary studies examples of these achievements are provided focusing on the major vegetation trends since the upper palaeolithic to the middle ages the techniques used for charcoal analysis in the reconstruction of quaternary vegetation are now being used to study tertiary charcoal and lignites the study of fossil charcoal can be a highly informative method for interpreting ancient ecosystems as species easily degraded may be preserved by charcoalification some results from the lower rhine embayment germany are presented here

thickness of the seismic slip zone this article reviews geologic and other evidence constraining the thickness of the principal slip zone psz that accommodates the bulk of coseismic shear displacement during an individual rupture event surface deformation from rupturing may occupy swaths tens of meters or more in width but trenches across active faults generally reveal that incremental slip is accommodated by a psz that is tens of centimeters or less in thickness geomorphic evidence coupled with the observations from trenching suggest a psz may stay well localized for distances of several kilometers through many rupture episodes mine exposures and exhumed fault zones demonstrate that pszs separating different lithologies within the fault core although contained within damage zones of variably fractured rock ranging up to hundreds of meters in thickness often comprise just a few centimeters of gouge ultracataclasite that have accommodated large finite displacements 1 km microstructural studies demonstrate incremental slip localized still further down to 1 10 mm as do other fault rock assemblages slickensides and slickenfibers fault veins of pseudotachylyte friction melt intravein septa in hydrothermal fault infills the accumulated evidence indicates that localization of coseismic shearing to less than 10 cm on planar faults is widespread throughout the crustal seismogenic zone with extreme localization to less than 1 cm not uncommon however some distributed coseismic shear may also develop especially at rupture irregularities coseismic reduction of shear resistance from friction melting t 1000 c or from transient thermal pressurization of aqueous fluids t 100 c requires slip during moderate to large earthquakes u 1 m to be restricted to narrow zones respectively a few centimeters or tens of centimeters in thickness given the evidence for slip localization the apparent scarcity of pseudotachylyte suggests either that seismic friction melting is a rare phenomenon or that pseudotachylyte is only rarely preserved in recognizable form within mature hydrated fault zones

global positioning system constraints on plate kinematics and dynamics in the eastern mediterranean and caucasus we present and interpret global positioning system gps measurements of crustal motions for the period 1988 1997 at 189 sites extending east west from the caucasus mountains to the adriatic sea and north south from the southern edge of the eurasian plate to the northern edge of the african plate sites on the northern arabian platform move 18 2 mm yr at n25 5 w relative to eurasia less than the nuvel 1a circuit closure rate 25 1 mm yr at n21 7 w preliminary motion estimates 1994 1997 for stations located in egypt on the northeastern part of africa show northward motion at 5 6 2 mm yr also slower than nuvel ia estimates 10 1 mm yr at n2 4 e eastern turkey is characterized by distributed deformation while central turkey is characterized by coherent plate motion internal deformation of 2 mm yr involving westward displacement and counterclockwise rotation of the anatolian plate the anatolian plate is de coupled from eurasia along the right lateral strike slip north anatolian fault naf we derive a best fitting euler vector for anatolia eurasia motion of 30 7 0 8 n 32 6 0 4 e 1 2 0 1 myr the euler vector gives an upper bound for naf slip rate of 24 1 mm yr we determine a preliminary gps arabia anatolia euler vector of 32 9 1 2 n 40 3 1 1 e 0 8 0 2 myr and an upper bound on left lateral slip on the east anatolian fault eaf of 9 1 mm yr the central and southern aegean is characterized by coherent motion internal deformation of 2 mm yr toward the sw at 30 1 mm yr relative to eurasia stations in the se aegean deviate significantly from the overall motion of the southern aegean showing increasing velocities toward the trench and reaching 10 1 mm yr relative to the southern aegean as a whole

the 17 august 1999 izmit earthquake on 17 august 1999 an earthquake of magnitude 7 4 shook northwestern turkey details on the earthquake9s characteristics and effects across northwestern turkey are provided and are put in the historical context of previous earthquakes in the region the earthquake was the seventh in a series of earthquakes migrating westwards along the north anatolian fault since 1939 information on historical earthquakes modeling and estimates of the slip rate along the fault indicate that the location and severity of the earthquake should not have come as a surprise

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

gps and geologic estimates of the tectonic activity in the marmara sea region nw anatolia a dense network of 52 global positioning system gps sites is used to determine the velocity field and strain rate pattern at the western end of the north anatolian fault zone nafz in the marmara sea region nw anatolia based on four gps campaigns carried out biannually between 1990 and 1996 the detailed kinematic field of crustal motion is calculated the southernmost station shows an average rate of 22 3 mm yr oriented westward relative to istanbul eurasia this value is indicative of the dextral strike slip motion of nw anatolia relative to the black sea the gps velocity field reveals that the sites located on the thrace black sea block show negligible motion relative to istanbul the gps based deformation pattern of three sections crossing the westward prolongation of the nafz is compared with neotectonic data both the gps and the neotectonic data give clear evidence that most of the deformation occurs along a relatively narrow e w oriented zone this belt extends from the single fault trace of the nafz through the gulf of izmit the marmara sea the arkoy region and the gulf of saros into the north aegean trough nat in addition the cross sections show the increasing influence of the n s oriented extension in the aegean sea region from the comparison of the directions and rates of shear and normal strain deduced from gps data with geologic and seismic observations we conclude that the most active zone of dextral shear follows a line along mudurnu valley the northern marmara sea and the saros trough where it joins the nat

near field investigations of the landers earthquake sequence april to july 1992 the landers earthquake which had a moment magnitude m w of 7 3 was the largest earthquake to strike the contiguous united states in 40 years this earthquake resulted from the rupture of five major and many minor right lateral faults near the southern end of the eastern california shear zone just north of the san andreas fault its m w 6 1 preshock and m w 6 2 aftershock had their own aftershocks and foreshocks surficial geological observations are consistent with local and far field seismologic observations of the earthquake large surficial offsets as great as 6 meters and a relatively short rupture length 85 kilometers are consistent with seismological calculations of a high stress drop 200 bars which is in turn consistent with an apparently long recurrence interval for these faults