modeling of the transport and deposition of tungsten in the scheelite bearing calc silicate gneisses of the montagne noire france scheelite bearing calc silicate gneisses csg oceur in the montagne noire within a series of dominant micaschists detailed petrographical and mineralogical studies reveal three successive stages of metamorphism and hydrothermal alteration 1 stage 1 a regional metamorphism at 550 c and 4 5 kb where no mineralization is formed 2 stage 2a a hydrothermal alteration at 500 to 450 c and 4 to 3 kb which is characterized by an intense sericitization of feldpars and deposition of sn in sn bearing cale silicates and 3 stage 2b a hydrothermal alteration characterized by the crystallization of idocrasegrossular in csg with concomittant precipitation of scheelite tungsten was transported through the micaschist environment and deposited as scheelite only in the csg of stage 2b at relatively low pressures to characterize the mechanism of tungsten transport tungsten speciation at high p t and scheelite solubility in aqueous solations buffered by the csg and by the micaschists assemblages were calculated it was found that h2wo 0 4 hwo 4 and wo 2 4 are the dominant tungsten aqueous species in h2o nacl one molal solutions at 500 c and 2 4 kb calculations also indicate that scheelite deposition is controlled by decreasing pressure and increasing activity of aqueous calcium in this system this is consistent with the petrographical and mineralogical observations the consequences of the presence of volatiles n2 ch4 co2 in the regional fluids were examined by determining the effect of n2 on tungsten speciation and scheelite solubility the addition of n2 up to 10 mol to the mineralizing fluids results in a marked increase in h2wo 0 4 and hwo 4 concentrations relative to wo 2 4 and in a large decrease of scheelite solubility this mechanism favours scheelite precipitation and accounts for the commonly observed association of w and sn deposits with graphitic series generating mixed volatiles fluids

tectonic rotations about vertical axes during the last 4 ma in part of the new zealand plate boundary zone the declinations of the primary magnetization of sedimentary rocks in the northern part of the new zealand plate boundary zone after thermal or alternating field cleaning have been used to determine tectonic rotations about vertical axes of rigid crustal blocks the pattern of rotations during the last 4 ma combined with structural style and continuity defines seven structural domains each ca 100 100 200 km across which contain crustal blocks up to 100 km across and 20 km thick large crustal blocks tens of km across in two of these domains have rotated clockwise more than 20 relative to one of the margins of the plate boundary zone in the last 4 ma their behaviour appears to be controlled by the nature of the plate boundaries such as the presence of an underlying subducted slab and the strength of the crust at the back of the overlying crustal wedge small crustal blocks 10 km across may have rotated clockwise through angles greater than 20 during the last 4 ma floating on an underlying zone of more distributed deformation the tectonic rotations of the large crustal blocks and the nature of the deformation at their boundaries combined with an interpolation of the relative plate positions can be used to reconstruct the plate boundary zone at ca 4 ma

earthquake generated tsunamis in the mediterranean sea scenarios of potential threats to southern italy italian civil defense project development of new technologies for the protection of the italian territory from natural hazards funded by the italian ministry of university and research

morphology and mechanics of submarine spreading a case study from the storegga slide spreading is a common type of ground failure in subaerial environments however this type of mass movement has hardly been documented in submarine settings in this paper we show that spreading covers at least 25 of the storegga slide scar area a giant submarine slide located offshore mid norway the morphological signature of spreading is a repetitive pattern of ridges and troughs oriented perpendicular to the direction of movement two modes of failure can be identified retrogressive failure of the headwall and slab failure and extension both involving the breakup of a sediment unit into coherent blocks these blocks are displaced downslope along planar slip surfaces limit equilibrium modeling indicates that loss of support and seismic loading are the main potential triggering mechanisms the extent of displacement of the spreading sediment is controlled by gravitationally induced stress angle of internal friction of the sediment pore pressure escape and friction the resulting block movement pattern entails an exponential increase of displacement and thinning of the failing sediment with distance downslope sediment properties explain the remaining spatial variation of ridge and trough morphologies associated with spreading

resurgent strike slip duplex development along the hitra snasa and verran faults more trondelag fault zone central norway abstract lineament analysis of the ene wsw verran and hitra snasa faults of the long lived more trondelag fault zone mtfz has revealed the presence of a complex array of anastomosing faults and fractures this has the geometric configuration of a major dextral strike slip fault zone and compares well with characteristic patterns of braided wrench faulting e g the san andreas fault system of california the fault array recognized in conjunction with the verran fault is clearly post caledonian and is considered to define a dextral strike slip duplex system associated with the parallel hitra snasa fault are riedel like structures which tend to point to an earlier component of sinistral movement rock products present along the hitra snasa fault and its secondary faults comprise mylonites hydrothermally altered rocks and small scale recrystallized breccias along the main verran fault evidence of late polyphasal deformation is seen in several discrete episodes of brecciation hydrothermal alteration and locally pervasive prehnite and stilbite veining the fault structures occurring along the hitra snasa and verran faults are thought to have originated as a sinistral fault system of late devonian age especially for the hitra snasa lineament subsequently strike slip movement reversed in sense and shifted locus towards the verran fault system during the late jurassic or early cretaceous during this strike slip reversal some earlier fractures related to the sinistral system were rejuvenated within the stress field of the evolving dextral duplex system strike slip displacements of a similar age are known from fault complexes on the norwegian continental shelf and in the northern north sea the regional picture indicates that the mtfz was almost certainly linked to the fault systems of northern scotland prior to the opening of the viking graben

evaporites and strata bound tungsten mineralization discoidal gypsum crystal cavities occur in quartzites that host varying amounts of strata bound scheelite mineralization near halls creek in western australia the host quartzites have been regionally metamorphosed to greenschist facies and are contained within a middle proterozoic sequence that includes pelites mafic and felsic volcanics and volcaniclastic rocks textural fluid inclusion and oxygen isotope data indicate that scheelite was present in the host quartzites prior to regional metamorphism the presence of crystal cavities after gypsum in the quartzites implies an evaporitic origin for this sequence the continental sabkha playa basins of the mojave desert california are suggested to be possible modern analogs e g searles lake where the tungsten content is up to 70 ppm wo sub 3 in brines and 118 ppm in muds and exceeds the amount of tungsten in all known deposits in the united states metamorphism of a continental evaporitic sequence containing tungsten could produce an assemblage of rocks very similar to those reported from several stratabound tungsten deposits some of these such as at halls creek may be related to original accumulations of tungsten in nonmarine evaporitic environments

earthquake clustering in the eastern mediterranean during historical times most coastal sectors which show evidence of holocene coseismic uplift in greece and the eastern mediterranean were raised during a short period called here the early byzantine tectonic paroxysm ebtp between the middle of the fourth and the middle of the sixth century a d the areas uplifted at that time include cephalonia and zante in the ionian islands lechaion and the perachora peninsula in the gulf of corinth the pelion coast of thessaly antikythira and the whole of western crete a coastal sector near alanya in southern turkey and the entire levant coast from hatay turkey to syria and the lebanon the amount of the ebtp uplift was generally between 0 5 m and 1 0 m but reached a maximum of about 9 m in southwestern crete in several areas zante pelion coast antikythira western crete alanya the ebtp uplifted shoreline is the only evidence of holocene emergence in other areas however a similar uplift occurred earlier in the holocene levant coast or more recently cephalonia evidence of preseismic subsidence prior to the ebtp uplift has been reported from thessaly antikythira and crete in both the latter islands the ebtp uplift was preceded by a series of about 10 coseismic small subsidence movements each measuring some tens of centimeters which took place in the preceding 3000 years no evidence was observed of postseismic vertical displacements

hercynian structure of the axial zone of the pyrenees the aran valley cross section spain france abstract in the axial zone of the pyrenees palaeozoic rocks crop out with superimposed hercynian and alpine deformation the hercynian structures present two domains infrastructure and suprastructure a complete crosssection of the central part of the axial zone of the pyrenees is presented in which hercynian structures of both domains can be observed in the aran valley cross section the infrastucture corresponds to the garona dome domain where the main hercynian structures are north vergent recumbent folds with an associated mainly flatlying foliation s 2 in the garona dome domain the peak of the medium to high grade metamorphism is simultaneous with the main hercynian structures the aran valley and noguera ribagorca areas correspond to the suprastructure in these domains the main hercynian structures are upright folds with an associated mainly steep lying foliation s 3 in these suprastructural domains low grade syn s 3 metamorphism is present this crosssection relates the structures of the infra and the suprastructure suggesting a deformational sequence for the axial zone of the pyrenees this sequence is deduced from the fact that the north vergent folds observed in the garona dome are earlier than the main structures of the suprastructure the boundary of the garona dome and the suprastructure is a decollement level observed at the base of the silurian the deformational sequence proposed here provides some constraints for models of hercynian evolution and the emplacement of the alpine structures of the pyrenees

block rotation by strike slip faulting structural and paleomagnetic evidence geometric analysis shows that motion of sets of strike slip faults should cause block rotation otherwise the distorted fault domain would not fit with its surrounding the sense of the block rotation depends on the sense of fault slip and the spacing and orientation of the faults all of which can be obtained from structural data the predictions of the geometric model can then be independently tested by paleomagnetic measurements the model was tested in northern israel structural data reveal several domains of contemporaneous right and left lateral strike slip faults paleomagnetic measurements show that in a domain of nnw trending left lateral faults blocks rotated 23 3 8 2 clockwise and in a domain of right lateral faults blocks rotated 22 4 9 0 anticlockwise these results are in agreement with the prediction of the geometric analysis of the structure the combined results of the heterogenous deformation of the area resembles a pure shear which allows n s extension by about 1 3 in other domains rotations of 34 6 9 1 and 53 1 11 0 were found in their original orientation the left and right lateral faults intersected at angles of 60 70 enclosing the principal axis of shortening in accordance with theories of brittle failure as a result of block rotations this angle is now larger and may reach 110 the results demonstrate large block rotations in different senses in domains of strike slip faults the independent structural and paleomagnetic data can be interpreted within the framework of a simple geometric model northern israel is considered to be a good model for this efficient mechanism of intraplate deformation which is expected to occur in similar tectonic settings elsewhere

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

geometry and kinematics of vertical axis rotations in fold and thrust belts abstract vertical axis rotations indicated by palaeomagnetic study are a common and important component of deformation in fold and thrust belts the kinematics of rotating thrust sheets may be best described as a combination of a far field rotation or translation in a planar geometry and a near field or local rotation so that the instantaneous rotation axis lies outside the body of the sheet this simplifies the thrust sheet kinematics significantly as it means that all the points on the sheet have a component of forward motion and the bounding fault is a thrust over all its area the consequences of a simple thrust sheet rotation for the interpretation of fault lineation data are investigated the lineations recorded in the footwall and the hangingwall are likely to be different the hangingwall lineations being skewed towards the direction of rotation the principal mechanism for local thrust sheet rotation is differential shortening either on folds or thrusts or by a combination of these structures the forward propagation of thrusting towards the foreland can accumulate large 120 rotations on the uppermost sheets these rotational thrust sheets cannot extend indefinitely along strike instead they terminate against lateral ramps or transfer faults sidewall duplexes may form as a consequence of rotation over a lateral ramp examples of rotational geometries from the subbetic zone of southern spain are described on a larger scale obliquely convergent orogenic wedges can evolve by rotation of faults with an initial thrust geometry into progressively greater components of strike slip motion reliable palaeomagnetic data are not always available for fold and thrust belts so independent evidence for rotational deformation is of great importance fold and thrust geometries particularly along strike variability in fold geometries highly variable axial traces of folds evidence for near synchronous refolding and the deviation of regional trends may all be a consequence of thrust sheet rotation detailed mapping and particularly the identification of the position of footwall and hangingwall cut offs can also provide strong evidence for rotation

postglacial seismicity offshore mid norway with emphasis on spatio temporal magnitudal variations abstract norway and its continental margin in spite of being located in an intraplate environment is of great interest from a neotectonic perspective influence on neotectonics stems both from the fact that this is a recently deglaciated region in which significant rebound is still occurring and from its proximity both to a rifted continental margin and to failed rift zones passive continental margins and rift related structures are the most seismically active ones within stable continental regions with a number of well documented earthquakes of magnitude 7 and higher as observed around the globe indeed the disparity in seismicity between such regions and plate boundary regions is greater in terms of return times than in terms of maximum magnitude a recent detailed assessment of neotectonics in fennoscandia has shown strong bedrock related evidence for several large magnitude m 7 earthquakes in the northern areas lapland while few if any similar observations have been made farther south a possible explanation for this is that postglacial earthquakes have been occurring on hidden thrusts in the south in fact several major structures have recently been mapped and shown to have capabilities to accommodate m 6 5 7 earthquakes without breaking the surface given that the largest historically known earthquake in fennoscandia is only of the order of m 5 8 it is likely therefore that the potentially largest magnitude in this region may be well above this

seismic activity inferred crustal stresses and seismotectonics in the rana region northern norway abstract the seismotectonic significance of the rana region is known both from the fact that this was the location of the largest known earthquake in fennoscandia in recent times the m s 5 8 6 2 earthquake of august 31 1819 and from its relatively high constant seismic activity also in the 20th century in order to study this region in more detail a local seismic network has been in operation there since july 1997 as part of the neonor neotectonics in norway project the network was primarily designed to detect possible activity on the basmoen fault which runs 50 km subparallel to the rana fjord and which shows signs of likely post glacial activity the results have revealed a quite complex spatio temporal distribution of seismic activity and has also shown no activity on the basmoen fault itself during the first 18 months of operation july 1997 january 1999 the network has detected 373 locatable seismic events of which 267 were local earthquakes most of these earthquakes occurred in five groups in the western parts of the network all five groups had similar nnw esw trends in epicenter locations and all have shallow foci 2 12 km similar to what has also been found earlier for other concentrated earthquake zones in northern norway and the magnitude range is between m l 0 1 and 2 8 earthquake focal mechanism solutions within the network reveal a predominance for normal faulting with the tensional stress axis perpendicular do the coastline implying an unusual coast parallel orientation of the principal horizontal compressive stress the earthquakes occur in a region of maximum post glacial uplift gradients which supports deglaciation flexure as a viable explanation for these earthquakes a certain influence from more local factors however tied in general to crustal in homogeneities cannot be ruled out

deformational behaviour of continental lithosphere deduced from block rotations across the north anatolian fault zone in turkey abstract theoretical considerations of lithosphere deformation across transform plate boundaries predict an expression in terms of 3istributed deformation the magnitude of rotation is expected to diminish away from the fault zone in a way which depends on the length of the fault the amount of displacement and the ductility of the lithosphere palaeomagnetic studies across the north anatolian transform fault zone which separates the eurasian plate and anatolian block in northern turkey show that clockwise rotations predicted from the sense of dextral motion are indeed present and have attained finite rotations of up to 270 during the 5 ma history of neotectonic deformation such rotations are however confined to narrow 10 km wide zones between system bounding faults and appear to have resulted from rotation in ball bearing fashion of equidimensional blocks a few kilometres in size outside of this zone only anticlockwise rotations are observed these are unrelated to deformation across the fault zone and record regional anticlockwise rotation of turkey which is complementing clockwise rotation of greece and accompanying neogene opening of the aegean sea the observed behaviour of continental lithosphere satisfies no plausible value of power law behaviour we therefore conclude that relative motion across this transform boundary occurs as a discrete zone of intense deformation within a brittle layer comprising the seismogenic upper crust this is presumed to be detached from a continuum deformation response to shearing in the lower crust and mantle beneath

earthquake source parameters along the hellenic subduction zone and numerical simulations of historical tsunamis in the eastern mediterranean abstract we studied source mechanism parameters and slip distributions of earthquakes with m w 5 0 occurred during 2000 2008 along the hellenic subduction zone by using teleseismic p and sh waveform inversion methods in addition the major and well known earthquake induced eastern mediterranean tsunamis e g 365 1222 1303 1481 1494 1822 and 1948 were numerically simulated and several hypothetical tsunami scenarios were proposed to demonstrate the characteristics of tsunami waves propagations and effects of coastal topography the analogy of current plate boundaries earthquake source mechanisms various earthquake moment tensor catalogues and several empirical self similarity equations valid for global or local scales were used to assume conceivable source parameters which constitute the initial and boundary conditions in simulations teleseismic inversion results showed that earthquakes along the hellenic subduction zone can be classified into three major categories 1 focal mechanisms of the earthquakes exhibiting e w extension within the overriding aegean plate 2 earthquakes related to the african aegean convergence and 3 focal mechanisms of earthquakes lying within the subducting african plate normal faulting mechanisms with left lateral strike slip components were observed at the eastern part of the hellenic subduction zone and we suggest that they were probably concerned with the overriding aegean plate however earthquakes involved in the convergence between the aegean and the eastern mediterranean lithospheres indicated thrust faulting mechanisms with strike slip components and they had shallow focal depths h

seismotectonics of the norwegian continental margin the norwegian continental margin and surrounding areas are seismically less active than some other passive margins worldwide indicating a potential earthquake deficit the adjacent oceanic crust is mostly aseismic except for parts of the lofoten and norway basins which have experienced rapid deposition of glacial sediments the excess load has enhanced the local stress field and in turn the seismic activity the marginal highs along the continent ocean transition and the part of the more and voring basins which experienced crustal extension prior to the early tertiary breakup are practically aseismic this region is also underlain by high velocity lower crust emplaced during breakup suggesting crustal strengthening which also may increase the return periods for the largest events farther landward a spatial correlation of seismic activity and the glacial sediment wedge suggests a causal relationship expressed through preferential rejuvenation of late jurassic early cretaceous faults the locally high seismic activity in the coastal region occurs in areas where the continental crust is relatively thick 25 30 km but still thinner than in the shield area farther east 45 50 km although stress relations are complex we suggest that increased stress due to appreciable postglacial rebound gradients in the coastal region may be a contributing factor while the stress field along the margin complies in general with the ridge push force we infer that regional and local stress enhancement factors are not only present in this region but also necessary for explaining the earthquake activity the relative importance of local stress sources is supported by several cases of 90 stress rotations relative to the ridge push direction the superposition of regional and local stress together with the existence of weakness zones and faults yields potentials for earthquakes primarily through structural reactivation

complex evolution of the erzincan basin eastern turkey abstract two new tectonic models are presented to explain the pull apart opening of the erzincan basin our field studies indicated that the erzincan basin is not a typical rhombic pull apart basin instead it has a rather complex single or two stage pull apart opening mechanism the basin was initially formed as a result of a 4 km wide releasing stepover and a 15 divergence angle between segments 1 and 2 of the north anatolian fault zone nafz along which the westward tectonic escape of the anatolian block has been taking place the single stage model refers to the partitioning of the transtensional deformation by coeval normal and strike slip displacements on parallel trending faults which remained since their initiation the two stage model infers that the basin opening was modified later by the formation of the left lateral ovacik fault which caused fragmentation of the anatolian block the two stage pull apart basin opening mechanism accounts for the observed geometry of the erzincan basin the present day geometry of the basin indicates that there had been 35 5 km of right lateral displacement along the nafz and 5 2 km of left lateral displacement along the ovacik fault

detachment and rotation of a metamorphic core complex during extensional deformation palaeomagnetic study of the catalina rincon core complex basin and range province arizona abstract the catalina rincon complex exposes a metamorphic core of mid crustal rocks exhumed by extensional tectonism along a major detachment exposed along the southeast side of the catalina rincon mountains near tucson arizona the juxtaposition of core complexes against high level crust segmented into rotated and tilted fault blocks is an important component to models for crustal extension and key questions surround the way s that cores are exhumed we report palaeomagnetic results from rocks beneath the detachment in the catalina rincon core and additional data from lavas and tuffs in adjoining hanging wall rocks immediately above the detachment magnetic remanence in the metamorphic core is carried predominantly by magnetite with a dominant wnw ese dual polarity direction a1 d i 288 50 n 59 components r 55 60 95 4 6 this remanence is interpreted to have been acquired through a broadened blocking temperature spectrum during protracted exhumation and cooling in oligocene times since the magnetic inclination accords with the mid cenozoic field it is difficult to explain this magnetization in terms of large later tilting and it appears to be the record of near vertical axis ccw rotation of 63 5 relative to cratonic north america although magnetic inclination identifies no significant horizontal axis rotation this could be fortuitous and hide the influence of magnetic anisotropy and resultant inclination shallowing to assess this contribution both anisotropy of magnetic remanence amr and anisotropy of magnetic susceptibility ams have been investigated ams resolves only weak fabrics comparable with the top ne mylonite deformational fabric near the detachment which probably dates from a mid eocene high temperature event amr shows that deflections of magnetic remanence of up to several tens of degrees into the foliation may be anticipated although weak alignment of the magnetite is likely to reduce this effect the full importance of horizontal axis tilting remains unresolved although a possible relict component in the core a2 d i 269 9 n 24 components r 22 91 95 6 6 is rotated 20 more ccw than a1 and also of presumed mid cenozoic cooling related origin it suggests that segments of middle crust comprising the exposed core might have been rotated by large amounts into their present position highly faulted early oligocene pantano formation volcanic rocks in the hanging wall immediately above the detachment zone appear to have rotated by a much smaller amount ccw on the south west side d i 161 45 6 sites and by larger variable amounts on the northeast side movements of the upper plate immediately above the detachment are difficult to resolve with precision due to complex fault block rotations although the underlying core complex has clearly undergone large differential slip relative to these cover rocks the magnitude of inferred vertical axis rotation of the catalina rincon core implies that it is not rooted into adjoining crust as proposed in classical simple shear models instead the core exposed below the detachment may be part of a fault carapace that has decoupled and rotated over a ductile lower crust

geometry and subcrop maps of shallow jurassic basins along the mid norway coast abstract interpretation of new seismic data from four inshore nearshore areas along the coast of mid norway yields important information on the geometry and stratigraphy of downfaulted jurassic sedimentary rocks three seismic units have been identified these are interpreted to be of middle to late jurassic age fangst group and melke formation half graben geometries related to normal fault movement are common for the areas although the beitstadfjorden basin and the griptarane area also record possible strike slip movements the structural development of the four areas can be related to tectonic movements along the more trondelag fault complex the jurassic basins along the coast of mid norway are directly comparable in size and geometry with previously unmapped deep seated basins in the voring basin we suggest that the inshore nearshore and offshore basins originated during the same extensional event in late jurassic early cretaceous times and that this basin forming event was regionally very extensive

seismicity and seismotectonics of norway and nearby continental shelf areas the earthquake activity of norway and nearby offshore areas is low to intermediate with few events above magnitude 5 recent significant improvements in instrumental coverage in parallel with a better utilization of older including historical data have shown that the seismicity in the south is predominantly confined to the coastal areas and to the viking graben while from the northern north sea to svalbard the earthquakes in a broad sense follow the continental margin fifty one focal mechanism solutions from these areas about half of them new reveal stress directions that clearly indicate a connection to the plate tectonic ridge push force at least for the areas at a minimum distance from the continental margin along the margin stress directions also indicate a possible connection to postglacial uplift as well as to lithospheric loading effects a dominance of normal faulting on the landward side and reverse faulting on the oceanic side agrees with this interpretation on a regional level the seismicity in these areas correlate quite well with geologic features such as grabens fault zones fault complexes fracture zones and the margin itself indicating that these structures act in a general sense as weakness zones in the presence of a regionally more stable stress field in the northern north sea however an area with quite anomalous stress orientations with strike slip faulting is found in a region transitional between normal and reverse faulting most of the earthquake foci are confined to the presumably brittle parts of the crust but many events are also located quite close to and on both sides of the moho discontinuity

stress transfer in the storegga area offshore mid norway abstract the recently discovered large gas field ormen lange within the storegga submarine slide area offshore mid norway poses important questions as to the origin of these large submarine slides and their possible implications in terms of the safety of the development and the production in this respect the present study was initiated with the main objective of investigating the possibility of stress transfer as triggering mechanism for multiple earthquake occurrence and hence for the storegga submarine slide ca 8200 years before present bp stress changes following different scenario earthquakes along the selected faults in the area are modeled and computed for a number of cases using the coulomb failure criterion we demonstrate the possibility of large earthquakes triggering multiple ruptures along neighbouring fault segments the combined effect of the co seismic slip and strong ground shaking due to a large earthquake m 7 accompanied by the stress transfer on the optimally oriented normal fault planes which are analogous to the slide scar may have played an important role for the triggering of the storegga submarine slide

on the cause of the 1908 messina tsunami southern italy 1 a century after the catastrophic event the sources of the 1908 messina southern italy earthquake and tsunami which caused at least 60 000 deaths remain uncertain through a simple backward ray tracing method we convert the tsunami travel time data reported in a 100 years old paper into distances and find that the sources of the earthquake and tsunami are different overturning a long held assumption reconsideration of the available tsunami bathymetric seismic and seismological data indicates that the tsunami was generated by an underwater landslide

multiple miocene block rotation in the bakony mountains transdanubian central range hungary abstract the bakony mountains of the transdanubian central range hungary are located in the western part of the pannonian basin their neogene structure is dominated by right lateral strike slip faults with offsets of up to 5 km these faults are organized in two sets the older one trending wnw is offset by the younger nw trending set neither set of faults i e the ne trending left lateral raba and balaton major strike slip faults extends across the boundary faults it is proposed here that the late miocene structural evolution of the bakony mountains can be best explained in terms of multiple block rotation on the basis of this simple geometric model a 15 counterclockwise rotation is suggested as a working hypothesis for the entire tectonic unit previous paleomagnetic measurements conform well to the block rotation predicted by the model the proposed detachment for the rotated rigid upper crustal blocks is a regional decoupling surface at an average depth of 10 km this surface probably emanated from a nappe system of cretaceous age

anhydrite bearing rocks from the rožna district moldanubian zone czech republic high grade metamorphosed exhalites several types of anhydrite bearing rocks have been found in the amphibolite facies metamorphosed rocks at the north eastern margin of the moldanubian zone anhydrite either forms monomineralic bands up to 40 cm thick or occurs in the form of disseminated grains in surrounding calc silicate gneiss together with feldspar scapolite amphibole pyroxene epidote and pyrite the isotopic composition of sulphur 34s 30 6 to 32 3 and strontium 87sr 86sr 0 70797 to 0 70781 in anhydrite may indicate a marine source of sulphate the isotopic ratio of strontium is in the same range as that of metamorphosed strata bound barite sulphide ores which have been previously described in the same area the 34s values of coexisting pyrite range from 21 4 to 22 5 the 34sanhydrite pyrite corresponding to the metamorphic temperature of 600 to 660 c in contrast to many submarine exhalative deposits the oxygen isotopic compositions of anhydrite 18o 9 3 to 10 2 are lighter than that of barite 18o 10 4 to 13 8 this indicates that the both minerals are not in isotopic equilibrium therefore it is probable that anhydrite and barite from the ro na district were deposited from fluids that contained different proportions of seawater and hydrothermal fluids or from hydrothermal fluids that underwent variable extent of oxygen isotope exchange with seafloor rocks the 13c values in calcite 13c 17 2 to 18 7 from anhydrite bearing rock are lower than those in distant marbles as graphite is absent in anhydrite and calcite bearing rocks impoverishment in the 13c isotope cannot be attributed to the graphite carbonate isotopic exchange during metamorphism it is proposed that low 13c values in carbonates are caused by pre metamorphic oxidation of organic matter in course of hydrothermal processes anhydrite and anhydrite bearing calc silicate gneiss from the north eastern part of the moldanubian zone are interpreted to be the high grade metamorphosed analogue of anhydrite rich exhalites commonly found in submarine exhalative hydrothermal deposits

tectonic rotations in the late palaeozoic continental margin of southern south america determined and dated by palaeomagnetism summary detailed palaeomagnetic studies of late palaeozoic rocks exposed in the uspallatacalingasta valley region located at about 32 s 69 5 w in the argentine andean chain have been recently accomplished previous results are discussed in valencio vilas 1985 and rapalini et al 1989 the most recent studies were carried out mainly on the thick sequences of late early permian to late permian rhyolites and ignimbrites assigned to the tambillos and horcajo formations both formations yielded palaeomagnetic pole positions p15 319 6 e 78 9 s7 n 16 k 33 5 ags 6 5 and p17 264 8 e 72 4 s n 26 k 6 4 ag5 12 respectively concordant with the late palaeozoic path of south america preliminary palaeomagnetic results from the middle carboniferous hoyada verde formation exposed in the same region suggest that these rocks carry a synfolding magnetization acquired during the late carboniferous as the palaeomagnetic pole position computed from partially corrected remanence directions c6 356 2 e 41 9 s d1 8 3 02 6 0 agrees with the late carboniferous poles from cratonic areas of south america this concordant position of c6 definitely rules out the possibility of a late palaeozoic allochthony of this section of the argentine andean chain the discordant positions previously found in late carboniferous and early early permian rocks of this region are interpreted as caused by large clockwise crustal block rotations that occurred not later than the late early permian a tectonic model is proposed to explain these rotations which suggests that they were associated with strike slip displacements parallel to the western continental margin of south america caused by an oblique subduction of the proto pacific plate during the early permian many tectonic and geologic observations fit this model the concordant position of c6 also suggests that a complex pattern of crustal block rotations should have developed in this continental margin other palaeomagnetic data suggest that similar rotations may have taken place in other areas of the argentine andean chain in the early permian

the geodynamics of the aegean and anatolia introduction the complexity of the plate interactions and associated crustal deformation in the eastern mediterranean region is reflected in many destructive earthquakes that have occurred throughout its recorded history many of which are well documented and intensively studied the eastern mediterranean region including the surrounding areas of western turkey and greece is indeed one of the most seismically active and rapidly deforming regions within the continents fig 1 thus the region provides a unique opportunity to improve our understanding of the complexities of continental tectonics in an actively collisional orogen the major scientific observations from this natural laboratory have clearly been helping us to better understand the tectonic processes in active collision zones the mode and nature of continental growth and the causes and distribution of seismic volcanic and geomorphological events e g tsunamis and their impact on societal life and civilization the tectonic evolution of the eastern mediterranean region is dominated by the effects of subduction along the hellenic aegean arc and of continental collision in eastern turkey anatolia and the caucasus northward subduction of the african plate beneath western turkey and the aegean region is causing extension of the continental crust and volcanism in the overlying aegean extensional province eastern turkey has been experiencing crustal shortening and thickening as a result of northward motion of the arabian plate relative to eurasia and the attendant postcollisional magmatism taymaz et al 1990 1991a b mcclusky et al 2000 2003 dilek pavlides 2006 and references therein fig 2 the resulting combination of forces the pull from the subduction zone to the west and push from the convergent zone to the east is causing the turkish plate to move southwestward bounded by strike slip fault zones the north anatolian fault zone nafz to the north and the east anatolian fault zone eafz to the south interplay between dynamic effects of the relative motions of adjoining plates thus controls large scale crustal deformation and the associated seismicity and volcanism in anatolia and the aegean region taymaz et al 2004

model simulations of tsunamis generated by the storegga slides abstract a mathematical model based on the hydrodynamic shallow water equations is developed for numerical simulation of water waves generated by the submarine storegga slides on the norwegian continental slope the equations are solved numerically by a finite difference technique computations of wave amplification effects reveal run up heights for the second storegga slide between 3 and 5 m in exposed areas along the eastern coast of greenland iceland and scotland and the western coast of norway the calculated run up heights agree remarkably well with possible tsunami wave heights deduced from geological evidences along the eastern coast of scotland the generated wave heights are strongly dependent on the acceleration of the slide the effects of shear stress at the interface between the water and the slide body has turned out to be important

revised and synthetic apparent polar wander paths of the african eurasian north american and indian plates and true polar wander since 200 ma we have reviewed paleomagnetic data available for the eurasian african north american and indian plates over the last 200 ma selection criteria are those generally accepted with an emphasis on evidence for lack of remagnetization accurate dating and proper structural analysis this results in 23 35 51 and 2 poles for eurasia africa north america and india respectively we believe that this limited set of higher quality data is more likely to reveal key features of apparent polar wander apw paths than averaging of larger data sets involving less stringent selection criteria we propose and describe revised apw paths but more importantly we next use relative motion models to transfer all data in a common reference frame we find good agreement between transferred data when they are averaged separately for each plate in independent 20 ma windows this is a check on consistency of paleomagnetic data kinematic models and of the geocentric dipole hypothesis transferred data from all plates are averaged in 20 ma windows to generate synthetic apw paths for all plates studied these synthetic paths are in agreement with the original revised apw paths that use only data from a single plate moreover both geographic and time resolution are improved spatial confidence intervals are of the order of 5 the synthetic paths display interesting features such as a previously ill recognized apw loop for eurasia paleomagnetic and hotspot apw are next compared and a determination of true polar wander tpw is derived we find significant tpw amounting to over 20 in the last 200 ma tpw appears to be episodic with a standstill between 180 and 110 ma there is general agreement with a previous study of livermore et al 1984 the tpw standstill appears to correlate with a time of decreasing reversal frequency ending with the cretaceous long normal superchron other periods of fast tpw would seem to correspond to increasing reversal frequency however it is suggested that the major tpw hairpin at 50 ma might correspond to the collision of india with eurasia tentative correlations with core or mantle indicators can be understood as a result of couplings between the core mantle and lithosphere we believe primarily related to episodic evolution of the d layer

probabilistic and deterministic seismic hazard results and influence of the sedimentary more basin ne atlantic abstract seismic hazard assessments have been conducted for the ormen lange gas field in the norwegian sea on the flank of the more basin the study used logic tree based probabilistic methods combined with semi deterministic methods for hazard contributions from mapped faults and the hazard was computed in terms of peak ground acceleration pga and spectral acceleration the probabilistic seismic hazard results were complemented by deterministic modelling in 1d wave number integration and 2d finite difference crustal models the deterministic modelling first of all elucidated the shaking duration problem indicating that thick offshore sediment structures like the ones in the more basin may significantly extend the shaking duration of an earthquake the presence of sedimentary layers with large velocity contrasts are responsible for this observation and a conventional soil amplification analysis would not have revealed this phenomenon a modelling along similar lines as indicated in the present paper may be recommended in certain vulnerable situations and in geologic provinces with thick sedimentary layers with significant internal velocity contrasts even though large earthquakes most likely have occurred in the region during the postglacial period the study could not resolve if the huge storegga slide which occurred about 8100 yb was triggered by an earthquake

quantification of risks associated with seabed instability at ormen lange the ormen lange gas field is located within the slide scar of the enormous storegga slide that took place about 8200 years ago there are strong indications that the storegga slide generated a tsunami wave hitting the coastlines of norway scotland and the faeroes the headwalls of the storegga slide are steep and their safety factor against sliding could be low an extensive study was therefore performed to evaluate the probability for new submarine slides and their potential consequences results of the study showed that the 1st party and 3rd part risks associated with potential slide activity in the ormen lange area are negligible

structure of the more basin mid norway continental margin abstract in the more basin offshore mid norway the basis of the cretaceous sequence reaches depths of more than 5000 m the basin is limited on its eastern margin by a system of extensional faults which probably were initiated in the triassic and which were active periodically throughout the aptian the internal basin floor is divided into subbasins by structural highs which are rotated fault blocks presumably rooted in the basement the main structuring of the basin started in late triassic and was followed by accelerating subsidence in the early cretaceous subsidence was interrupted by a mild phase of inversion in the latest cretaceous and a more pronounced inversional phase in the eocene miocene the latter developed folds with wavelengths in the order of kilometers and local low angle reverse faults and the inversion of depocenters

mesozoic fault systems deformation and fault block rotation in the andean forearc a crustal scale strike slip duplex in the coastal cordillera of northern chile abstract in this paper we discuss the evolution and tectonic significance of the mesozoic trench parallel fault systems which affected the coastal cordillera and their relation to magmatism and crustal rotation the oldest extensional fault system separates basement from rift related late triassic and younger sedimentary units this system i subsequently developed into a wider extensional fault system which acted as the locus of magma ascent and emplacement of the coastal batholith during much of the jurassic to earliest cretaceous period this extensional fault system defined the forearc sliver during this period and was the consequence of a retreating subduction boundary during the early cretaceous c 132 125 ma the kinematics of this fault system changed to transtension ii and accommodated a major component of left lateral strike slip motion the principal fault being the atacama fault zone along which plutons continued to be emplaced the final phase of pluton emplacement within the coastal cordillera appears to be c 106 ma after which this magmatic arc and fault system was abandoned an late cretaceous arc and fault system iii developed some 20 ma later and located some 50 km to the east in what is now the central valley of northern chile this paper seeks to show that the coastal cordillera was deformed as a whole by this late cretaceous fault system iii which formed a crustal scale left lateral transpressional duplex during this deformation the thermally weakened crust was dissected into a series of large scale blocks bounded by nw trending left lateral strike slip faults which merge into a nne ssw fault zone which forms the eastern boundary to the duplex we term this eastern boundary zone the central valley fault zone cvfz and this together with the nw trending faults defines the duplex system which we refer to as a whole as the coastal cordillera fault system ccfs iii we have traced the ccfs duplex between 25 s and 29 s and suspect that it continues northward the timing of the deformation is constrained to be post 106 ma the age of coastal cordillera arc abandonment and pre tertiary based on the deformation and pluton emplacement in and along the central valley fault zone palaeomagnetic data from the fault bound blocks within the ccfs duplex indicate 35 45 of post early cretaceous clockwise rotation with no substantial latitudinal motion we suggest that the observed fault kinematics of the ccfs are consistent with this crustal scale duplex model where rotations would have occurred in response to left lateral transpression

eastern mediterranean tectonics and tsunami hazard inferred from the ad 365 earthquake historical accounts describe an earthquake and tsunami on 21 july ad 365 that destroyed cities and drowned thousands of people in coastal regions from the nile delta to modern day dubrovnik the location and tectonic setting of this earthquake have been uncertain until now here we present evidence from radiocarbon data and field observations that western crete was lifted above sea level by up to 10 m synchronously with the ad 365 earthquake the distribution of uplift combined with observations of present day seismicity suggest that this earthquake occurred not on the subduction interface beneath crete but on a fault dipping at about 30 within the overriding plate calculations of tsunami propagation show that the uplift of the sea floor associated with such an earthquake would have generated a damaging tsunami through much of the eastern mediterranean measurement of the present rate of crustal shortening near crete yields an estimate of 5 000 yr for the repeat time of tsunamigenic events on this single fault in western crete but if the same process takes place along the entire hellenic subduction zone such events may occur approximately once every 800 yr in the year ad 365 an earthquake and tsunami destroyed much of the eastern mediterranean coastal regions the distribution of uplift at the time suggests that the earthquake occurred on a fault within the overriding plate at the subduction zone beneath crete and not on the subduction interface itself

earthquakes tsunamigenic middle earth violent uplift of western crete in ad 365 generated a mediterranean wide tsunami that tossed boats onto house tops in alexandria egypt although a similar earthquake may not recur for 5 000 years contiguous fault segments could rupture sooner

meta evaporite sequence exhalative chemical sediments and associated rocks in the proterozoic willyama supergroup south australia implications for metallogenesis abstract the willyama supergroup comprises proterozoic meta sedimentary and meta igneous rocks in western new south wales and eastern south australia and contains the giant broken hill pb zn ag deposit in addition to numerous small stratiform stratabound and vein mineral deposits new lithological geochemical and fluid inclusion data from the olary block west of broken hill suggest the presence of former evaporite rocks now metamorphosed to a variety of chemically and mineralogically unusual lithologies these evaporite rocks overlie relatively oxidised strata and are in turn overlain by reduced graphite bearing pelites rocks of sodic composition abound represented by albite quartz rich rocks calcite actinolite epidote garnet clinopyroxene inferred to represent metamorphosed analcime rich strata of felsic volcaniclastic provenance with variable proportions of carbonates for example calcite dolomite trona and shortite these rocks are interspersed with potassic rocks possibly also with an evaporitic origin in addition to normal clastic meta sediments the presence of halogen rich minerals in a distinctive mineral assemblage hypersaline fluid inclusions pseudomorphic voids and minerals after gypsum and carbonate in addition to tourmalines with isotopically light boron isotopes is interpreted as evidence for a non marine evaporite parent rock for portions of the olary block types of mineral occurrences in the olary block form a continuum between chemical sediments formed by the exhalations of hydrothermal fluids to intrasediment deposits inferred to have been formed due to the chemical changes imposed on these and or diagenetic fluids during their passage through the sedimentary pile disseminated stratabound pyrite including cobaltian types and chalcopyrite extend along strike for many kilometres and are interpreted to have formed by a diagenetic mechanism the presence of massive sulphide bearing strata iron formations barite tourmalinite and manganiferous rocks are typical of chemical sediments derived from hot spring sources the olary block meta evaporites have similar whole rock compositions to tertiary analcime rich rocks of the green river formation wyoming these new data imply that portions of the adjacent broken hill block may also comprise meta evaporites for example the quartz albite rich strata of the thackaringa group and the calcsilicates of the lower broken hill group and that the disseminated cobaltian pyrite mineralisation in the thackaringa group may not be of exhalative origin

a palaeomagnetic study of the sivas basin central turkey crustal deformation during lateral extrusion of the anatolian block abstract the sivas basin is a complex collage of eocene and younger rocks located within the wedge shaped eastern margin of the anatolian block between the dextral north anatolian fault zone and the sinistral eastern anatolian fault zone it has been subject to ongoing deformation by movement of the arabian block into eurasia and concomittant sideways expulsion of the anatolian block post collisional deformation since mid miocene times has been dominated by n s to nw se compression expressed by thrusting and strike slip faulting cretaceous and eocene rocks were magnetically overprinted to variable degrees during the collisional phase although these overprints have since been rotated mostly anticlockwise rocks emplaced during the neotectonic history are high fidelity palaeomagnetic recorders of subsequent block movements regional anticlockwise rotation is recognised across the basin with differential rotation of fault and thrust bounded blocks an absence of perceptible differences between group mean rotations identified from miocene pliocene and quaternary units shows that most regional rotation has been concentrated within the latest phase of the neotectonic history during quaternary times at an average rate of 10 ma commencement of this rotation postdates initiation of the north anatolian fault zone implying that compression following collision was accomodated initially by crustal thickening during late miocene and pliocene times subsequent anticlockwise rotations have resulted from sideways expulsion of blocks to the south of the central anatolian thrust along major ne sw sinistral faults to achieve the crustal shortening resulting from n s compression these fault orientations and their sense of motion are explained by a prandtl model involving deformation of a triangular plastic terrane the anatolian block between two rigid plates eurasia and afro arabia the variations in regional rotation identified by palaeomagnetism show that average contemporary anticlockwise rotation of anatolia revealed by gps data 1 2 ma is achieved by variable and locally large block rotations between major thrusts and strike slip faults

the north anatolian fault zone distributed neogene deformation in its northward convex part abstract the north anatolian fault zone is composed of two almost rectilinear branches which join in a northward convex bend in this bent zone the pontide anatolide collisional system has been cut across by two transpressional belts of fold and thrust and wrench faults of lower neogene age these structures were reactived during the neotectonic period the time of deposition of the pontus group for both of these deformational events and up to the present the tectonic regime remained generally transpressional with a nw se direction of compression and a ne sw direction of extension it is only recently during the upper pleistocene that the dextral wrench faults became more localized and more straight than previously the complexity of the eastern part of the north anatolian fault zone is better understood if one takes into account the role of inherited miocene pliocene transpressional structures

seismo and neotectonics in finnmark kola and the southern barents sea part 2 seismological analysis and seismotectonics abstract a detailed review and analysis of seismological data acquired since 1979 from finnmark kola and the southern barents sea has provided a much improved delineation of the earthquake activity in that region in the barents sea the seismicity is confined only to the western areas while the finnmark kola coastal areas show some seismicity only north and east of murmansk in the rybachi cape tereberski region further inland there are several clear seismicity lineations that to some extent can be correlated with postglacial faults including the ne sw striking stuoragurra fault in finnmark the spatial correlation between seismicity and mapped faults is interpreted in general as a reflection of broad zones of weakness that respond to the present day stress field a detailed analysis of the earthquakes in this area has also shown a dynamic consistency in that they reveal a reverse faulting pattern that is consistent with a detailed geological study that includes a core drilling the dominant horizontal stress direction in this region is nnw sse consistent with the ridge push effect

why are there no clockwise rotations along the north anatolian fault zone mechanical analysis of lithospheric deformation associated with an intracontinental transform fault suggests that it should be associated with a pattern of vertical axis rotations governed by the length of the fault its displacement and the mechanical properties of the lithosphere paleomagnetic results from two transects across the north anatolian fault zone indicate that there have been no measurable clockwise rotations on a regional scale associated with neogene dextral strike slip motion along the fault the data come from two groups of volcanic rocks that have been dated by k ar whole rock geochronology and have yielded ages ranging from 45 3 3 1 m y to 41 8 1 3 m y eocene and 21 7 1 5 m y to 7 5 0 2 m y miocene the absence of clockwise rotations suggests one of the following explanations 1 in contrast to the assumptions underlying current mechanical analyses deformation in the upper crust may not directly reflect the flow in the lithosphere and is localized along a single fault trace 2 deformation is distributed but rotations have been prevented by the presence of elongate fault blocks subparallel to the trace of the main fault 3 displacement along the north anatolian fault may be too small or the rheologic properties of the lithosphere such that rotations about vertical axes cannot be resolved instead of the predicted clockwise rotations measured declinations show that there has been approximately 30 of anticlockwise rotation of both the eocene and miocene volcanic rocks this suggests that no significant rotation occurred between eocene and miocene times and that the anticlockwise rotation occurred either immediately before or concurrent with the plio pleistocene slip on the north anatolian fault

suppression of earthquakes by large continental ice sheets the interior regions of antarctica and greenland are aseismic no earthquake larger than body wave magnitude 4 5 5 0 is known for either except along coastal zones or continental shelves here i advance an explanation for this lack of seismic activity in terms of pressure effects produced by the continental ice sheets that mantle both continents

three recent larger earthquakes offshore norway three earthquakes of magnitude around 5 occurred offshore western norway on 5th february 1986 on 8th august 1988 and on 23rd january 1989 these earthquakes representing the highest seismic activity level in this area for at least 30 years were all felt by people over most of southern and central norway focal mechanism solutions for these earthquakes indicate thrust faulting along n s to nne ssw striking fault planes in response to nw se compressional stress most probably of plate tectonic origin a number of high quality digital recordings of the ground motions at various distances from these and other recent earthquakes in norway have shown that source spectral as well as wave attenuation characteristics in this area are reasonably consistent with what has been derived from other intraplate areas

block versus continuum deformation in the western united states abstract the relative role of block versus continuum deformation of continental lithosphere is a current subject of debate continuous deformation is suggested by distributed seismicity at continental plate margins and by cumulative seismic moment sums which yield slip estimates that are less than estimates from plate motion studies in contrast block models are favored by geologic studies of displacement in places like asia a problem in this debate is a lack of data from which unequivocal conclusions may be reached in this paper we apply the techniques of study used in regions such as the alpine himalayan belt to an area with a wealth of instrumental data the western united states by comparing plate rates to seismic moment release rates and assuming a typical seismogenic layer thickness of 15 km it appears that since 1850 about 60 of the pacific north america motion across the plate boundary in california and nevada has occurred seismically and 40 aseismically the san francisco bay area shows similar partitioning between seismic and aseismic deformation and it can be shown that within the seismogenic depth range aseismic deformation is concentrated near the surface and at depth in some cases this deformation can be located on creeping surface faults but elsewhere it is spread over a several kilometer wide zone adjacent to the fault these superficial creeping deformation zones may be responsible for the palaeomagnetic rotations that have been ascribed elsewhere to the surface expression of continuum deformation in the lithosphere our results support the dominant role of non continuum deformation processes with the implication that deformation localization by strain softening must occur in the lower crust and probably the upper mantle our conclusions apply only to the regions where the data are good and even within the western united states i e the basin and range deformation styles remain poorly resolved nonetheless we maintain that block motion is the deformation style of choice for those continental regions where the data are best

crustal stress in the northern north sea as inferred from borehole breakouts and earthquake focal mechanisms the regional stress field in the northern north sea offshore western norway has been studied through the acquisition and analysis of directions of maximum horizontal compression sh as extracted from borehole breakouts and from earthquake focal mechanism solutions the results indicate that the regional stress field is dominated by nw se compression with good consistency between shallow borehole breakouts 2 5 km depth and deeper earthquakes 10 25 km depth the broad spatial consistency in stress direction indicates that the main stress field is related to factors of primarily plate tectonic origin and the results are in good agreement with the western europe trend found in earlier investigations the tampen spur region in the northern north sea has been subjected to particularly complex deformation with two dominating fault directions trending nw se and ne sw from tampen spur in the west to the sogn graben in the east an anomalous stress field is indicated with ne sw oriented maximum horizontal compressions this anomaly is clearly seen both in the borehole breakout data and in the earthquake data possible sources for this anomaly are discussed and include postglacial uplift and or lateral variations in the physical properties of the crust

seismo and neotectonics in finnmark kola peninsula and the southern barents sea part 1 geological and neotectonic framework abstract as a background for assessing the seismo and neotectonics of the finnmark kola peninsula region emphasis has been directed towards the lineament framework involving a careful examination of digital landsat tm imagery integrated with a variety of data sets ranging from geophysics and digital elevation models to microtectonics based on a detailed field structural control of many of the multiphase lineaments in this 70 000 km2 area of the northeastern part of the fennoscandian shield as well as microscopic investigation of the fault mylonites and breccias five principal lineament sets were distinguished of the nw se polyphasal megafractures the murmansk shear zone carries geological and isotopic evidence of an archaean tectonothermal history and demarcates an important terrane boundary lineaments irrespective of their trends were classified according to their significance in the regional geological framework some lineaments are clearly associated with gravity and aeromagnetic anomalies and probably extend to deep crustal levels quite a few of the prominent faults within lineament zones were reactivated in post glacial times in one area in finnmark core drilling through a se dipping post glacial reverse fault has confirmed its listric shape at depth earthquake focal mechanisms for this same fault are presented in the second part of this dual contribution

structure and seismic stratigraphy of the griptarane area more basin margin mid norway continental shelf abstract the mesozoic succession on the landward side of griptarane offshore mid norway reflects an upward change from lower jurassic alluvial deposits to middle jurassic marine continental deposits into upper jurassic lower cretaceous marine deposits in the latest jurassic there was deposition of submarine fans along faults associated with major extensional deformation and fault block rotation probably in volgian times this phase coincided with nw se extension and rifting in the slorebotn sub basin and at haltenbanken an onlap surface is interpreted to represent the kimmerian unconformity and to mark the approximate position of the jurassic cretaceous boundary some wnw ese to e w oriented faults exhibit reverse movements while e w trending folds indicate n s compression this compression is interpreted to coincide with a late early cretaceous phase of sinistral transpression in the gossa high and slorebotn sub basin and inversion and doming in the more and voring basins the predominance of wnw ese to nw se and ene wsw to ne sw trending structures indicates that the griptarane area has been influenced by the stress regimes of the more trondelag fault complex as well as the stress regimes in the regions further offshore

stress transferred by the 1995 mw 6 9 kobe japan shock effect on aftershocks and future earthquake probabilities the kobe earthquake struck at the edge of the densely populated osaka kyoto corridor in southwest japan we investigate how the earthquake transferred stress to nearby faults altering their proximity to failure and thus changing earthquake probabilities we find that relative to the pre kobe seismicity kobe aftershocks were concentrated in regions of calculated coulomb stress increase and less common in regions of stress decrease we quantify this relationship by forming the spatial correlation between the seismicity rate change and the coulomb stress change the correlation is significant for stress changes greater than 0 2 1 0 bars 0 02 0 1 mpa and the nonlinear dependence of seismicity rate change on stress change is compatible with a state and rate dependent formulation for earthquake occurrence we extend this analysis to future mainshocks by resolving the stress changes on major faults within 100 km of kobe and calculating the change in probability caused by these stress changes transient effects of the stress changes are incorporated by the state dependent constitutive relation which amplifies the permanent stress changes during the aftershock period earthquake probability framed in this manner is highly time dependent much more so than is assumed in current practice because the probabilities depend on several poorly known parameters of the major faults we estimate uncertainties of the probabilities by monte carlo simulation this enables us to include uncertainties on the elapsed time since the last earthquake the repeat time and its variability and the period of aftershock decay we estimate that a calculated 3 bar 0 3 mpa stress increase on the eastern section of the arima takatsuki tectonic line attl near kyoto causes fivefold increase in the 30 year probability of a subsequent large earthquake near kyoto a 2 bar 0 2 mpa stress decrease on the western section of the attl results in a reduction in probability by a factor of 140 to 2000 the probability of a mw 6 9 earthquake within 50 km of osaka during 1997 2007 is estimated to have risen from 5 6 before the kobe earthquake to 7 11 afterward during 1997 2027 it is estimated to have risen from 14 16 before kobe to 16 22

the ad 365 crete earthquake and possible seismic clustering during the fourth to sixth centuries ad in the eastern mediterranean a review of historical and archaeological data abstract historical and archaeological data are used to test geological claims that in the fourth to sixth centuries ad the eastern mediterranean experienced an unusual clustering of destructive earthquakes the early byzantine tectonic paroxsym a review of historical accounts of a notable earthquake at this time that of 21 july ad 365 indicates that this event destroyed nearly all the towns in crete and was followed by a tsunami which devastated the nile delta the ad 365 event was also probably responsible for reported or observed destruction in ancient towns of west cyprus and libya this earthquake is most likely to be identified with a hellenic arc subduction zone event of great m 8 magnitude as testified by up to 9 m of uplift in western crete dated by previous geological studies to around this time historical and archaeological data also support the hypothesis that the fourth to sixth centuries ad was a period of abnormally high seismicity in the eastern mediterranean the high seismicity rates of this period may reflect a reactivation of all plate boundaries in the region dead sea transform east anatolian fault north anatolian fault hellenic arc cyprus arc fault