carbo permian pteridophyll leaf fragments from an amphibolite facies basement tauern window austria graphitic schists from the pennine basement tauern window austria contain fragments of pteridophyll leaves they are preserved despite the overall strong deformation and metamorphism at amphibolite facies conditions 525 c 750 100 mpa due to a particular strain path with volume loss by pressure solution they were determined as cf callipteridium sp indicating a permo carboniferous age this depositional age is similar to radiometric age data obtained for the intrusion of nearby metagranitoids indicating either tectonic contacts between the metagranitoids and the graphite schists or a very active and rapidly changing tectonic regime during the hercynian event

behavior of the southernmost san andreas fault during the past 300 years surficial creep occurs at low rates along the coachella valley segment of the san andreas fault which has not produced a large earthquake during the period of historical record geodetic data indicate however that the crust adjacent to this segment of the san andreas fault is accumulating strain at a high rate furthermore neotectonic and paleoseismic data indicate that the fault does produce very large earthquakes every two to three centuries in view of its long term behavior the occurrence of creep along the surficial trace of the fault in the coachella valley is of particular interest along two short reaches of the san andreas fault in the coachella valley measurements of offset geological deposits and man made structures and from alignment arrays and creep meters show that slip rates of 2 4 mm yr near indio and near the salton sea have persisted for the past three centuries this slow aseismic surficial creep is not a transient precursor to seismic failure of this segment of the fault we suggest that the coachella valley segment of the san andreas fault creeps in its upper few kilometers this behavior may be due to tectonically induced high pore pressures in the coarse sediments that abut the fault

mesozoic evolution of the tisza mega unit the south eastern part of the basement of the pannonian basin is made up of variscan crystalline complexes and early mesozoic formations showing striking affinity with the corresponding formations in the southern margin of the european plate this large composite structural unit which is actually an exotic terrane of european plate origin has been named the tisza mega unit based upon relevant data of the pre tertiary basement of southern hungary the reconstruction of the position of the tisza terrane in the early alpine evolutionary stages the process of its separation and break off from the european plate and results of its eo alpine deformations are summarised in the present paper in the variscan and early alpine evolutionary stages the area of the later tisza mega unit was located at the margin of the european plate during variscan orogeny terrane accretion led to intensive deformation and metamorphism in this belt this was followed by transpressional tectonics and the development of molasse basins in the late and post variscan stages and passive margin evolution after the neotethys opening in the middle triassic the separation of the tisza mega unit began with incipient continental rifting along the axis of the later ligurian penninic vahic oceanic branch in the late triassic the end of terrigenous material deposition in the most external zones and a coeval change in fossil assemblage point to the separation of the tisza block from the european plate in the early bathonian significant rotation of the tisza mega unit and coeval paroxysm of alkaline rift type basalt volcanism took place in the early cretaceous in the mid cretaceous due to the northward motion of the adria block and the related closure of the westernmost neotethys basin the extensional regime changed to a compressional one leading to onset of the nappe stacking and low grade regional metamorphism within the tisza microplate in the foreland of the nappe systems flexural basins came into existence that are characterised by flysch type sedimentation in the early tertiary the north eastward motion of the alcapa and tisza dacia blocks led to the formation of the present day heterogeneous basement of the pannonian basin

late holocene lacustrine chronology and archaeology of ancient lake cahuilla california freshwater lakes existed intermittently in the salton trough of southern california during the late holocene the lakes formed north of the subaerial colorado river delta whenever the colorado river flowed west into the trough instead of south to the gulf of california water filled the trough to a maximum altitude of 12 m stratigraphy radiocarbon dates and supplementary evidence document four lacustral intervals of lake cahuilla between a d 700 and 1580 archaeological sites are associated with the 12 m shoreline and their occupation correlates with these lacustral intervals

evidence for prehistoric earthquakes on the superstition hills fault from offset geomorphic features offset geomorphic features along the superstition hills fault show evidence for at least one slip event prior to the 1987 surface rupture and possibly as many as four to five earlier prehistoric earthquakes we documented several geomorphic features that appeared offset by multiple events by making detailed topographic maps offset features were abundant along reaches of the fault with high topographic relief and large displacement slip distribution for the penultimate event as recorded by offset rills streams and shrub coppice dunes is very similar to the slip distribution from the 1987 earthquake through april 1988 this similarity may prove to be fortuitous if afterslip from the 1987 event continues to increase the total slip for this earthquake but if afterslip associated with the 1987 event ceases in the near future then the past two earthquakes were nearly identical in slip and the superstition hills fault may be expected to produce characteristic earthquakes of roughly magnitude 6

measurement of outflow from a snowbank with basal ice by kathy l young and antoni g lewkowicz department of geography erindale college university of toronto mississauga ontario l5l i c6 canada abstract a technique is described for measuring melt water outflow from snowbanks that develop a basal ice layer the method involves excavation of channels across ice exposed at the lower edge of a snowbank in order to divert run off into a portable flume since discharges are measured before the water comes into contact with the soil sub surface flow and soil moisture changes do not have to be assessed outflow discharges recorded at a perennial snowbank site on melville island n w t canada compare favourably with energy balance calculations and measure ments of ablation introduction snow melt is regarded as the most significant hydrological input to non glacierized basins in alpine e g jordan 1983 sub arctic e g dunne and others 1976 low arctic e g landals and gill 1973 onesti and walti 1983 and high arctic environments e g lewkowicz and french 1982 woo 1983 woo and others 1983 consequently a thorough understanding of the relationship between snow melt and stream run off is essential for many aspects of resource development in these regions walker and lake 1973 colbeck 1977 the two main approaches used to determine run off resulting from snow melt are modelling and direct measurement vertical and horizontal movements of melt water in homogeneous and layered snow packs have been modelled extensively e g col beck 1971 1972 1973 1974 1977 and flow equations have been tested in alpine areas e g jordan 1979 and in the sub arctic dunne and others 1976 price 1977 more recently a simulation model has been developed which describes water movement through flow fingers the growth of ice lenses and wetting front advance in high arctic snow packs marsh and woo 1984b it also predicts basal ice growth and run off in spite of these advances more work is required before models can accurately describe melt water movement and quantify run off for snowbanks which are both non uniform in depth and heterogeneous in structure field measurements of run off from snow will continue to be necessary for the development and verification of such models direct measurement of snow melt and run off in northern areas has relied mainly on instrumented hill slope plots a review of researchers and their methods has been presented by steer and woo 1983 in most studies run off was measured on the ground surface down slope of the snow this increases the potential for error in estimating snow melt since evapotranspiration sub surface flow and ground storage changes all have to be considered e g dunne and black 1971 dunne and others 1976 lewkowicz and french 1982 steer and woo 1983 this paper describes a technique for the direct measurement of outflow from snow that has developed a basal ice layer the method can be used in snow of heterogeneous depth and structure and reduces the possibility of error in assessing melt since discharges are 358 measured before the water comes into contact with the substrate the technique could be employed to provide observed outflow values for comparison with predictions from snow melt models to determine snow melt inputs to experimental plots or to a drainage basin or to estimate the energy balance of ablating snow the method was tested at the site of a perennial snowbank on south east melville island northwest territories canada figs i and 2 in july and august 1986 the discharge data obtained compare favourably with independent measurements of the energy balance and snow ablation method the method can be used to monitor outflow from any snowbank that possesses a basal ice layer basal ice develops when negative ground temperatures are present beneath a melting snow pack and a sufficiently large soil thermal gradient exists for latent heat released by freezing to be conducted into the substrate woo and heron 1981 woo and others 1982 the basal ice layer has a low permeability and once formed beneath a snow pack is usually effective in preventing subsequent melt waves from

post collisional rapid exhumation and erosion during continental sedimentation the example of the late variscan salvan dorenaz basin western alps the salvan dorenaz intramontane basin formed between ca 308 293 ma as an asymmetric graben along crustal scale transtensional fracture zones within the aiguilles rouges crystalline massif western alps and represents a feature of the post collisional evolution of the variscan orogens it contains 1 5 1 7 km of continental clastic deposits which were eroded from granitic volcanic and metamorphic rocks textural and compositional immaturity of the sandstones and the numerous lithic fragments with low chemical and physical stability suggest only short range transport 40ar 39ar analyses of detrital muscovite are interpreted to represent cooling of the crystalline basement below the respective closure temperatures ages from detrital muscovite range between ca 280 330 ma 40ar 39ar white mica plateau ages from granitic boulders range between 301 312 ma and suggest rapid cooling the very short time interval recorded between the 40ar 39ar cooling ages and the stratigraphic age of the host sediment suggests that considerable portions of the upper crust were removed prior to the formation of the basin late variscan granitic boulders document surface exposure and erosion of late carboniferous granites during early stages of the infilling of the basin therefore unroofing of basement units magmatic activity and formation of the fault bounded salvan dorenaz basin were acting concomitantly and are highly suggestive of extensional tectonics when compared with other orogens this situation seems specific to the variscan especially the exclusively young ages of detrital material however modern analogous may exist

slope sediment yield in arid lowland continuous permafrost environments canadian arctic archipelago abstract surface wash erosion was measured at runoff plots on low to moderate slopes in clayey and sandy silts underlain by continuous permafrost on the fosheim peninsula ellesmere island due to snow redistribution in winter total precipitation on the plots varied from 34 to 150 mm with corresponding surface runoff values of 0 to 102 mm where runoff occurred at least 80 of it was derived from snowmelt suspended sediment removal was plot data precipitation vegetation and surface grain size from the fosheim peninsula and banks island were used to develop a statistical model of suspended sediment removal by surface wash on undisturbed slopes for any given grain size the model predicts a rise in erosion from zero precipitation because of an absence of runoff to a peak at about 50 mm a decline as precipitation increases to 300 mm and a further increase in erosion beyond this inflection point this non linear response is due to the complex interaction of moisture primarily snow and vegetation cover erosion at any given precipitation value varies through three orders of magnitude depending on surface grain size the maximum erosion predicted is 1 kg m 2 a 1 for a runoff plot with 1100 mm of precipitation a corresponding vegetation cover of 77 and a median surface grain size of 7

faunal response to transgressive regressive cycles example from the jurassic of western india abstract upper callovian to oxfordian shelf sediments at ler in the kachchh basin western india are interpreted in terms of transgressive regressive cycles the transgressive phases are represented by thin layers of reworked and bored concretions sometimes in association with skeletal concentrations the regressive phases are documented by much thicker units of largely fine grained sediments the benthic fauna of transgressive and regressive phases differes markedly and thus mirrors the sedimentary cycles during transgressive phases non sedimentation produced hard substrates colonized mainly by byssate cemented or pedicle attached suspension feeding epifaunal species whilst sediment input during regressive phases lead to soft substrate conditions characterized by infaunal deposit and suspension feeders as well as by epifaunal opportunists whereas the composition of the regressive fauna remains fairly constant through time that of successive transgressive faunas often differs drastically this is possibly due to a greater environmental sensitivity of epifaunal taxa as compared to infaunal taxa

reactivated basement structures affecting the sedimentary facies in a tectonically quiescent epicontinental basin an example from nw switzerland abstract the jurassic deposits in the southern part of central europe accumulated in a shallow epicontinental sea and their deposition has usually been believed to have corresponded to a phase of tectonic quiescence neither on conventional seismic records nor in outcrops obvious indications of synsedimentary tectonics were found nonetheless subtle variations in lithofacies and thickness occur above faults in the crystalline basement in fact preexisting structures became reactivated in the jurassic during major extensional phases when the tethys and the north atlantic opened this reactivation led to differential subsidence and or to rotation of fault bounded blocks but the sediments were deformed mainly flexurally as vertical movements in the basement were dissipated by triassic salt thus the depositional area was morphologically differentiated into swells and depressions in siliciclastic muddy environments swells were characterized by hardbottoms and hiatus beds depressions were filled by distal tempestites and gravity deposits in carbonate settings reefs nucleated on swells marls and muds were deposited in depressions many of them gravity deposits reactivation of faults occurred only during short episodes and was not synchronous throughout the study area and reactivation of individual faults was episodic and probably controlled by the palaeostress field and the faults orientation reactivation of deep rooted faults is also documented by hydrothermal activity which led to vein mineralization and alteration of minerals today exposed in nearby basement units the chronostratigraphic ages of the hydrothermal processes coincide with phases of enhanced subsidence during the sinemurian aalenian bajocian bathonian and oxfordian in turn facies changes of the sedimentary cover should be useful to predict basement structures when no seismic records are available

variable rates of late quaternary strike slip on the san jacinto fault zone southern california three strike slip displacements of strata with known approximate ages have been measured at two locations on the san jacinto fault zone minimum horizontal offset between 5 7 and 8 6 km in no more than 0 73 m y northeast of anza indicates 8 12 mm yr average slip rate since late pleistocene time two measures of more recent displacement are based on trenching studies of stratigraphic offsets on the coyote creek fault in western imperial valley horizontal slip of 1 7 m has been calculated for the youngest sediment of lake cahuilla since its deposition 275 510 yr b p the corresponding slip rate is 2 8 5 0 mm yr right lateral offset of 10 9 m measured on a buried stream channel older than 5060 yr b p but younger than 6820 yr b p yields average slip rates for the intermediate time periods 400 to 6000 yr b p of 1 2 mm yr the average rates of slip for these three time intervals suggest a relatively quiescent period for the san jacinto fault zone from about 4000 b c to about 1600 a d to the extent that long term variations in seismic activity of major strike slip faults elsewhere are known fluctuations in slip rate for the san jacinto fault would not appear to be abnormal if the san jacinto and adjacent segments of the san andreas fault alternately assume dominant roles in absorbing motion between the pacific and american plates perhaps even more recently than 400 yr ago the san andreas fault south of the transverse ranges expressed most of the motion but has since become relatively inactive

uavsar observations of triggered slip on the imperial superstition hills and east elmore ranch faults associated with the 2010 m 7 2 el mayor cucapah earthquake the 4 april 2010 m 7 2 el mayor cucapah earthquake that occurred in baja california mexico and terminated near the u s mexican border caused slip on the imperial superstition hills and east elmore ranch faults the pattern of slip was observed using radar interferometry from nasa s uninhabited aerial vehicle synthetic aperture radar uavsar instrument collected on 20 21 october 2009 and 12 13 april 2010 right lateral slip of 36 9 and 14 2 mm occurred on the imperial and superstition hills faults respectively left lateral slip of 9 2 mm occurred on the east elmore ranch fault the widths of the zones of displacement increase northward suggesting successively more buried fault motion to the north the observations show a decreasing pattern of slip northward on a series of faults in the salton trough stepping between the el mayor cucapah rupture and san andreas fault most of the motion occurred at the time of the m 7 2 earthquake and the uavsar observations are consistent with field creepmeter gps and envisat observations an additional 28 1 mm of slip at the southern end of the imperial fault over a 1 km wide zone was observed over a 1 day span a week after the earthquake suggesting that the fault continued to slip at depth following the mainshock the total moment release on the three faults is 2 3 1023 1 2 1024 dyne cm equivalent to a moment magnitude release of 4 9 5 3 assuming shallow slip depths ranging from 1 to 5 km

understanding the pre variscan and variscan basement components of the central tauern window eastern alps austria constraints from single zircon u pb geochronology new single grain and within grain u pb zircon ages from the central tauern window help sorting out the time dimension among the various variscan and pre variscan basement components that were strongly overprinted by alpine orogeny single grain isotope dilution id tims u pb zircon geochronology of three basisamphibolit samples yield protolith formation ages of 351 2 349 1 and 343 1 ma laser ablation icp ms and id tims u pb detrital zircon dating of the biotitporphyroblastenschiefer constrained the maximum time of sedimentation to between 362 6 ma and 368 17 ma paragneisses from the zwolferzug yield maximum sedimentation ages from 345 5 ma ion microprobe data to 358 10 ma zircons from gabbroic clasts and detrital zircons from a meta agglomerate from the habach phyllite give an upper intercept age of 536 8 ma and a near concordant age of 506 9 ma respectively hence apart from the habach phyllite the maximum sedimentation ages of the metasediments investigated range from upper devonian to lower carboniferous consequently the basisamphibolit the biotitporphyroblastenschiefer and the paragneisses of the zwolferzug form parts of the variscan basement series the basisamphibolit 351 343 ma is distinct both in space and time of formation from the zwolferzug garnet amphibolite c 486 ma which forms part of the pre variscan basement

hillslope runoff processes and models abstract hillslope hydrology is concerned with the partition of precipitation as it passes through the vegetation and soil between overland flow and subsurface flow flow follows routes which attenuate and delay the flow to different extents so that a knowledge of the relevant mechanisms is important in the 1960s and 1970s hillslope hydrology developed as a distinct topic through the application of new field observations to develop a generation of physically based forecasting models in its short history theory has continually been overturned by field observation thus the current tendency particularly among temperate zone hydrologists to dismiss all hortonian overland flow as a myth is now being corrected by a number of significant field studies which reveal the great range in both climatic and hillslope conditions some recent models have generally attempted to simplify the processes acting for example including only vertical unsaturated flow and lateral saturated flows others explicitly forecast partial or contributing areas with hindsight the most complete and distributed models have generally shown little forecasting advantage over simpler approaches perhaps trending towards reliable models which can run on desk top microcomputers the variety now being recognised in hillslope hydrological responses should also lead to models which take account of more complex interactions even if initially with a less secure physical and mathematical basis than the richards equation in particular there is a need to respond to the variety of climatic responses and to spatial variability on and beneath the surface including the role of seepage macropores and pipes which call into question whether the hillside can be treated as a darcian flow system

late pleistocene and holocene paleoearthquake activity of the olinghouse fault zone nevada paleoseismic trenching and fault surface trace mapping indicate that the olinghouse fault zone a northeast trending left lateral strike slip fault located in the northern walker lane nevada has been the source of multiple latest pleistocene and holocene surface rupturing earthquakes a trench exposure near the eastern end of the fault records two and possibly three earthquakes after 3360 190 cal yr b p and two trenches at the western end of the fault contain evidence for two earthquakes after 19 800 630 cal yr b p with the most recent earthquake occurring after 1935 70 cal yr b p the apparent higher frequency of recent earthquakes at the eastern end of the fault may reflect triggered slip on the olinghouse fault zone due to earthquakes on the conjugate northwest trending right lateral pyramid lake fault repeated late pleistocene and holocene earthquakes on the olinghouse fault zone demonstrate that northwest directed right lateral shear of the northern walker lane is accommodated in part by northeast trending left lateral faults

moment tensor solutions for the 24 november 1987 superstition hills california earthquakes the teleseismic long period waveforms recorded by the global digital seismograph network from the two largest superstition hills earthquakes are inverted using an algorithm based on optimal filter theory these solutions differ slightly from those published in the preliminary determination of epicenters monthly listing because a somewhat different improved data set was used in the inversions and a time dependent moment tensor algorithm was used to investigate the complexity of the main shock the foreshock origin time 01 54 14 5 m b 5 7 m s 6 2 had a scalar moment of 2 3 1025 dyne cm a depth of 8 km and a mechanism of strike 217 dip 79 rake 4 the main shock origin time 13 15 56 4 m b 6 0 m s 6 6 was a complex event consisting of at least two subevents with a combined scalar moment of 1 0 1026 dyne cm a depth of 10 km and a mechanism of strike 303 dip 89 rake 180

fault slip rates and earthquake histories for active faults in southern california abstract within the context of the historical record of seismicity we review the geological data bearing on the quaternary slip rates and paleoearthquake histories of active faults in southern california

facies and basin architecture of the late carboniferous salvan dorenaz continental basin western alps switzerland france the salvan dorenaz basin formed during the late palaeozoic within the aiguilles rouges crystalline basement western alps as an asymmetric intramontane graben elongated in a ne sw direction and bounded by active faults at least 1700 m of fluvial alluvial fan and volcanic deposits provide evidence for a strong tectonic influence on deposition with long term average subsidence rates of 0ae 2m m yr 1 the early basin fill was associated with coarse grained alluvial fans that were dominated by braided channels unit i these issued from the south western margin of the basin the fans then retreated to a marginal position and were overlain by muddy floodplain deposits of an anastomosed fluvial system unit ii that drained towards the ne deposition of thick muds resulted from a reduction in the axial fluvial gradient caused by accelerated tectonic subsidence overlying sand rich meandering river deposits unit iii document a reversal in the drainage direction from the ne to the sw caused by synsedimentary tectonism reflecting large scale topographic reorganization in this part of the variscides with subsidence now preferentially in the w and sw and uplift in the e and ne coarse grained alluvial fan deposits unit iv repeatedly prograded into and retreated from the basin as documented by coarsening upward cycles tens of metres thick reflecting smaller scale tectonic cycles volcanism was active throughout the evolution of the basin and u pb isotopic dating of the volcanic deposits restricts the time of basin development to the late carboniferous 308 295 ma 40 ar 39 ar ages of detrital white mica indicate rapid tectonic movements and exhumation of the nearby basement in unit i youngest ages are close to that of the host sediment but the age spectrum is wide in unit ii high subsidence and or sedimentation rates coincide with very narrow age spectra indicating small homogeneous catchment areas in unit iii age spectra became wider again and indicate growing catchment areas

evolution of an early permian extensional detachment fault from synintrusive mylonitic flow to brittle faulting grassi detachment fault orobic anticline southern alps italy

footwall uplift in an orogenic wedge the tauern window in the eastern alps of europe abstract in the tauern window tw the deepest structural units of the eastern alps are exposed in a 30 160 km antiform european basement and cover occur under nappes of oceanic penninic units and continental origin austroalpine nappes the tertiary structural history of the tw is related to a rapid uplift of 20 30 km since oligocene times structural mapping revealed 1 detachment and folding of the cover units and stacking of orthogneiss sheets 2 constrictional folding of the entire duplex with amplitudes and half wavelengths of several kilometres 3 backthrusting and backfolding along the northern margin of the tw and 4 displacement along steep dip divergent strike slip faults the strain history is complex and related to all these deformation phases the most uniform structural element is a stretching parallel to the long axis of the tw and its major fold axes strain did not contribute to tw uplift because ductile n s shortening was compensated by e w extension restoration of the tw shows that the exposed structures are not sufficient to explain the tw uplift by analogy with the engadine window and the western alps where seismic data are available a deep seated duplex is suspected the tw uplift is best explained in a dextral transpressive regime

the elmore ranch and superstition hills earthquakes of 24 november 1987 introduction to the special issue on 24 november 1987 two significant earthquakes occurred along the southern san jacinto fault zone and related structural elements in southern california not far from the international border these two events the elmore ranch earthquake m 6 2 at 0154 gmt and the superstition hills earthquake m 6 6 at 1315 gmt both moment magnitudes from sipkin 1989 and their aftershocks have yielded a rich harvest of geological seismological and engineering data pertinent to the cause and effect of earthquakes in this region where the southern san jacinto fault zone enters the salton depression from the peninsula ranges bordering it on the southwest fig 1 this special issue of the bulletin presents 18 geologic and seismologic investigations of these earthquakes a collection of papers born in el centro california on 8 and 9 february 1988 at a meeting attended by approximately 60 scientists interested in these earthquakes for one reason or another

hydrological and sediment yield response to summer rainfall in a small high arctic watershed in cold regions the response and related antecedent mechanisms that produce flood flows from rainfall events have received limited study in 2007 a small watershed at cape bounty melville island nunavut was studied in detail during the melt season two rainfall events on june 30 and july 22 totalling 9 2 and 10 8 mm respectively represented significant contributions to seasonal discharge and sediment transport in a year with a low winter snowpack the precipitation events elevated discharge and suspended sediment concentrations to twice the magnitude of the nival melt and generated the only measurable downstream lacustrine turbidity current of the season in two days rainfall runoff transported 35 of the seasonal suspended sediment load in contrast to 29 transported over the nival freshet the magnitude and intensity of the rain events were not unusual in this setting but the rainfall response was substantial in comparison with equivalent past events exceptional temperatures of july 2007 generated early deep permafrost thaw and ground ice melt the resultant increase in soil moisture amplified the subsequent rainfall runoff and sediment transport response these results demonstrate the importance of antecedent moisture conditions and the role of permafrost active layer development as an important factor in the rainfall runoff and sediment transport response to precipitation events copyright 2009 john wiley sons ltd

triassic rifts and facies patterns in western and central europe the triassic evolution of western and central europe was governed by regional crustal extension that induced the subsidence of a complex network of grabens and troughs these formed an integral part of the arctic north atlantic and the tethys central atlantic gulf of mexico rift and rift wrench systems which in the course of the mesozoic and cenozoic developed into major break up axes of pangea

the role of soil pipes as a slope runoff mechanism subarctic yukon canada pipeflow in subarctic slopes provides a preferential runoff mechanism that bypasses the soil matrix rapidly conveying water to the stream extensive soil piping occurs in the central wolf creek basin yukon at the interface of the organic and mineral horizons flow in these pipes are ephemeral transmitting water only when the water table is within or above the zone where pipes occur during snowmelt pipeflow began several days after the onset of surface runoff pipeflow contribution increased until ground thaw lowered the water tables leaving matrix flow within the organic layer as the dominant mode of runoff pipeflow accounted for 21 of runoff during the 15 day melt period of 1997 following melt pipeflow recurred only during two intense summer rainstorms each yielding different pipeflow response characteristics during melt pipeflow closely followed the daily snowmelt cycles and responded earlier than the integrated slope runoff in the summer pipeflow hydrographs rose and fell much quicker than direct storm runoff from the entire slope which was dominated by fast matrix flow within the organic layer pipeflow contributing areas were relatively small but their extent changed with hillslope wetness analysis revealed that the manning flow formula can be combined with contributing areas to simulate pipeflow discharges unlike temperate environments where frozen ground is not a factor the frost table position significantly controls the position of the phreatic surface and must be considered in any models of pipeflow in permafrost slopes

occurrence of surface flow on arctic slopes southwestern cornwallis island surface flow on arctic slopes is due to a rise of the suprapermafrost water table above the ground surface the active layer therefore has to be saturated or surface flow will be lost to infiltration in spring snowmelt supplies abundant water to the slopes but a shallow frost table restricts the active layer storage capacity this produces extensive surface flow delivering considerable volumes of water downslope as overland flow or rill runoff as the snowpacks are reduced and ground thaw increases the subsurface storage capacity surface flow declines in magnitude and in areal coverage during most summers subsurface flow dominates except when occasional rainstorms of high intensity raise the water table above the ground to rejuvenate surface runoff the occurrence of surface flow is controlled by slope material slope profile and the water balance spatial and temporal changes in these controlling variables always result in a highly dynamic pattern of surface flow on arctic slopes

rupture process of the ms 6 6 superstition hills california earthquake determined from strong motion recordings application of tomographic source inversion abstract we analyze strong motion recordings of the m s 6 6 superstition hills earthquake to determine the timing location spatial extent and rupture velocity of the subevents that produced the bulk of the high frequency 0 5 to 4 hz seismic energy radiated by this shock the earthquake can be characterized by three principal subevents the largest ones occurring about 3 and 10 sec after initiation of rupture timing relationships between pulses on the seismograms indicate that the three subevents are located within 8 km of each other along the northern portion of the superstition hills fault the two largest subevents display different directivity effects we apply a tomographic source inversion to the integrated accelerograms to determine the slip acceleration on the fault as a function of time and distance based on a one dimensional fault model the azimuthal distribution of amplitudes for the second subevent can be largely explained by a rupture that propagated about 2 km to the southeast along the superstition hills fault at a velocity about equal to the p wave velocity an alternative model with rupture propagating to the northeast along a conjugate fault plane can also account for the observed directivity of this subevent but it is not supported by the aftershock distribution the third subevent ruptured to the southeast along an 8 km long portion of the superstition hills fault at about the shear wave velocity this rupture propagation caused the relatively large accelerations and velocities observed in strong motion records for stations southeast of the hypocenter the long time intervals between the subevents and their relative proximity to each other indicate a very slow component to the rupture development the southern half of the superstition hills fault did not generate significant high frequency strong ground motion although it showed substantial co seismic surface displacement the subevents are situated along the same northern portion of the fault where most of the aftershocks are located the locations of the subevents appear to be controlled by bends in the fault mapped at the surface and by changes in basement structure at depth

kinematics and age of syn intrusive detachment faulting in the southern alps evidence for early permian crustal extension and implications for the pangea a versus b controversy permian basin formation and magmatism in the southern alps of italy have been interpreted as expressions of a wsw ene trending dextral megashear zone transforming early permian pangea b into late permian pangea a between 285 and 265 ma in an alternative model basin formation and magmatism resulted from n s crustal extension to characterize permian tectonics we studied the grassi detachment fault a low angle extensional fault in the central southern alps the footwall forms a metamorphic core complex affected by upward increasing top to the southeast mylonitization two granitoid intrusions occur in the core complex the synmylonitic val biandino quartz diorite and the postmylonitic valle san biagio granite u pb zircon dating yielded crystallization ages of 289 1 4 5 ma for the former and 286 8 4 9 ma for the latter consequently detachment related mylonitic shearing took place during the early permian and ended at 288 ma but kinematically coherent brittle faulting continued considering 30 anticlockwise rotation of the southern alps since early permian the extension direction of the grassi detachment fault was originally n s even though a dextral continental wrench system has long been regarded as a viable model at regional scale the local kinematic evidence is inconsistent with this and rather supports n s extensional tectonics based on a compilation of 200 u pb zircon ages we discuss the evolution and tectonic framework of late carboniferous to permian magmatism in the alps

seismicity and fault interaction southern san jacinto fault zone and adjacent faults southern california implications for seismic hazard the southern san jacinto fault zone is characterized by high seismicity and a complex fault pattern that offers an excellent setting for investigating interactions between distinct faults this fault zone is roughly outlined by two subparallel master fault strands the coyote creek and clark san felipe hills faults that are located 2 to 10 km apart and are intersected by a series of secondary cross faults seismicity is intense on both master faults and secondary cross faults in the southern san jacinto fault zone the seismicity on the two master strands occurs primarily below 10 km the upper 10 km of the master faults are now mostly quiescent and appear to rupture mainly or solely in large earthquakes our results also indicate that a considerable portion of recent background activity near the april 9 1968 borrego mountain rupture zone m l 6 4 is located on secondary faults outside the fault zone we name and describe the palm wash fault a very active secondary structure located about 25 km northeast of borrego mountain that is oriented subparallel to the san jacinto fault system dips approximately 70 to the northeast and accommodates right lateral shear motion the vallecito mountain cluster is another secondary feature delineated by the recent seismicity and is characterized by swarming activity prior to nearby large events on the master strand the 1968 borrego mountain and the april 28 1969 coyote mountain m l 5 8 events are examples of earthquakes with aftershocks and subevents on these secondary and master faults mechanisms from those earthquakes and recent seismic data for the period 1981 to 1986 are not simply restricted to strike slip motion dipslip motion is also indicated teleseismic body waves long period p and sh of the 1968 and 1969 earthquakes were inverted simultaneously for source mechanism seismic moment rupture history and centroid depth the complicated waveforms of the 1968 event m o 1 2 10 19 nm are interpreted in terms of two subevents the first caused by right lateral strike slip motion in the mainshock along the coyote creek fault and the second by a rupture located about 25 km away from the master fault our waveform inversion of the 1969 event indicates that strike slip motion predominated releasing a seismic moment of 2 5 10 17 nm nevertheless the right lateral nodal plane of the focal mechanism is significantly misoriented 20 with respect to the master fault and hence the event is not likely to be associated with a rupture on that fault from this and other examples in southern california we conclude that cross faults may contribute significantly to seismic hazard and that interaction between faults has important implications for earthquake prediction

subsidenz und tektonik des saar nahe beckens sw deutschland the saar nahe basin in sw germany is one of the largest permo carboniferous basins in the internal zone of the variscides its evolution is closely related to movements along the hunsruck boundary fault which separates the rhenohercynian and the saxothuringian zones recent deep seismic surveys indicate that the saar nahe basin formed in the hanging wall of a major detachment which soles out at lower crustal levels at about 16 km depth oblique extension along an inverted variscan thrust resulted in the formation of a half graben within more than 8 km of entirely continental strata accumulated the structural style within the basin is characterized by normal faults parallel to the basin axis and orthogonal transfer fault zones balanced cross section construction and subsidence analysis indicate extension of the orogenically thickened lithosphere by 35 subsidence modeling shows discontinuous depth dependent extension with laterally varying extension factors for crust and mantle lithosphere thus the offset between maximum rift and thermal subsidence can be explained by a zone of mantle extension shifted laterally with respect to the zone of maximum crustal extension

a crustal scale cross section through the tauern window eastern alps from geophysical and geological data a restorable geological cross section through the entire crust of the tauern window is presented it is drawn from surface geology and seismic data of the transalp vibroseis section using balancing software the architecture of the window is characterized by three horses in a large duplex structure and folded granitic sills the duplex was later uplifted along two large faults at its northern rim the first is a blind fault along the deep reaching sub tauern ramp with a displacement of 17 km the tip of the hanging wall block wedged underneath the austro alpine and penninic nappes and caused a triangle structure this led to backthrusting and backfold ing within the marginal rocks of the window at the second one the tauern north boundary fault occurred in our retrodeformation a throw of c 3 km a total shortening of the crust or parts of the crust of c 60 km in north south direction led to uplift of the tauern window

collapse of a hercynian tibetan plateau into a late palaeozoic european basin and range province the large width the importance of crustal shortening and the likelihood of thick crust in the late palaeozoic hercynian or variscan belt of southern europe suggest a tectonic evolution analogous to the evolution of the tibetan plateau and its neighbouring himalaya1 and of the altiplano and other high plateaux of the andes here we extend dewey and burke s analogy1 of the hercynian chain with tibet to include the subsequent stage of pervasive normal faulting and crustal extension and thinning which characterize the active tectonics of tibet parts of the high andes and the basin and range province of western north america it appears that normal faulting and rifting also characterize the late palaeozoic tectonic activity of the hercynian chain

neotectonics and intraplate continental topography of the northern alpine foreland research on neotectonics and related seismicity has hitherto been mostly focused on active plate boundaries that are characterized by generally high levels of earthquake activity current seismic hazard estimates for intraplate domains are mainly based on probabilistic analyses of historical and instrumental earthquake catalogues the accuracy of such hazard estimates is limited by the fact that available catalogues are restricted to a few hundred years which on geological time scales is insignificant and not suitable for the assessment of tectonic processes controlling the observed earthquake activity more reliable hazard prediction requires access to high quality data sets covering a geologically significant time span in order to obtain a better understanding of processes controlling on going intraplate deformation the alpine orogen and the intraplate sedimentary basins and rifts in its northern foreland are associated with a much higher level of neotectonic activity than hitherto assumed seismicity and stress indicator data combined with geodetic and geomorphologic observations demonstrate that deformation of the northern alpine foreland is still on going and will continue in the future this has major implications for the assessment of natural hazards and the environmental degradation potential of this densely populated area we examine relationships between deeper lithospheric processes neotectonics and surface processes in the northern alpine foreland and their implications for tectonically induced topography for the environmental tectonics project entec the upper and lower rhine graben urg and lrg and the vienna basin vb were selected as natural laboratories the vienna basin developed during the middle miocene as a sinistral pull apart structure on top of the east alpine nappe stack whereas the upper and lower rhine grabens are typical intracontinental rifts the upper rhine graben opened during its late eocene and oligocene initial rifting phase by nearly orthogonal crustal extension whereas its neogene evolution was controlled by oblique extension seismic tomography suggests that during extension the mantle lithosphere was partially decoupled from the upper crust at the level of the lower crust however whole lithospheric folding controlled the mid miocene to pliocene uplift of the vosges black forest arch whereas thermal thinning of the mantle lithosphere above a mantle plume contributed substantially to the past and present uplift of the rhenish massif by contrast oblique crustal extension controlling the late oligocene initial subsidence stage of the lower rhine graben gave way to orthogonal extension at the transition to the neogene the entec project integrated geological geophysical geomorphologic geodetic and seismological data and developed dynamic models to quantify the societal impact of neotectonics in areas hosting major urban and industrial activity concentrations the response of europe s intraplate lithosphere to late neogene compressional stresses depends largely on its thermo mechanical structure which in turn controls vertical motions topography evolution and related surface processes

slope runoff processes and flow generation in a subarctic subalpine catchment hillslope runoff was studied in a subarctic subalpine environment to improve understanding of runoff generation processes and the mechanisms whereby water moves from hillslopes to the stream runoff characteristics of four hillslopes were examined between 1997 and 1999 each with distinct soils frost topography and vegetation lateral fluxes were confined to hillslopes with porous organic soils overlying less permeable mineral substrates setting up a two layer flow system whereby most drainage occurs as quickflow in the porous organic layer as matrix flow and or as preferential flow in pipes rills and interconnected surface depressions during snowmelt meltwater infiltrated and percolated the porous frozen organic layers with little resistance percolation ceased at the organic mineral interface due to the impermeable nature of frozen mineral soils forming a perched saturated zone and initiating runoff snowmelt runoff was greater on slopes with greater snow water equivalent and reduced organic layer thickness in summer runoff was greatest on slopes where wet conditions were sustained by inflow stormflow hydrographs responded rapidly to rainfall while exhibiting extended recessions compared with temperate regions where sustained inflow occurred the recession limb showed two segments to reflect different source areas of stormflow production recession analysis was used to quantify contributing areas which were highly variable and controlled largely by hillslope wetness and organic layer properties results indicate that the concept of variable source area for runoff generation applies to subarctic subalpine catchments

a silent mw 4 7 slip event of october 2006 on the superstition hills fault southern california 1 during october 2006 the 20 km long superstition hills fault shf in the salton trough southern california slipped aseismically producing a maximum offset of 27 mm as recorded by a creepmeter we investigate this creep event as well as the spatial and temporal variations in slip history since 1992 using ers 1 2 and envisat satellite data during a 15 year period steady creep is punctuated by at least three events the first two events were dynamically triggered by the 1992 landers and 1999 hector mine earthquakes in contrast there is no obvious triggering mechanism for the october 2006 event field measurements of fault offset after the 1999 and 2006 events are in good agreement with the interferometric synthetic aperture radar data indicating that creep occurred along the 20 km long fault above 4 km depth with most of the slip occurring at the surface the moment released during this event is equivalent to a mw 4 7 earthquake this event produced no detectable aftershocks and was not recorded by the continuous gps stations that were 9 km away modeling of the long term creep from 1992 to 2007 creep using stacked ers 1 2 interferograms also shows a maximum creep depth of 2 4 km with slip tapering with depth considering that the sediment thickness varies between 3 km and 5 km along the shf our results are consistent with previous studies suggesting that shallow creep is controlled by sediment depth perhaps due to high pore pressures in the unconsolidated sediments

peak temperature patterns of polyphase metamorphism resulting from accretion subduction and collision eastern tauern window european alps a study with raman microspectroscopy on carbonaceous material rscm raman microspectroscopy on carbonaceous material rscm from the eastern tauern window indicates contrasting peak temperature patterns in three different fabric domains each of which underwent a poly metamorphic orogenic evolution domain 1 in the northeastern tauern window preserves oceanic units glockner nappe system matrei zone that attained peak temperatures tp of 350 480 c following late cretaceous to palaeogene nappe stacking in an accretionary wedge domain 2 in the central tauern window experienced tp of 500 535 c that was attained either within an exhumed palaeogene subduction channel or during oligocene barrovian type thermal overprinting within the alpine collisional orogen domain 3 in the eastern tauern subdome has a peaktemperature pattern that resulted from eo oligocene nappe stacking of continental units derived from the distal european margin this pattern acquired its presently concentric pattern in miocene time due to post nappe doming and extensional shearing along the katschberg shear zone system kszs tp values in the largest hochalm dome range from 612 c in its core to 440 c at its rim the maximum peak temperature gradient 70 c km 1 occurs along the eastern margin of this dome where mylonitic shearing of the katschberg normal fault knf significantly thinned the subpenninic and penninic nappe pile including the pre existing peak temperature gradient

the irish variscides problems perspectives and some solutions a review is presented of interpretations made to date of the irish variscides and the various models of late palaeozoic crustal evolution an examination is then made of the factors controlling variscan strain in ireland including lithological competence basement fabric and basement cover thickness from this the difficulties of recognizing variscan fronts and fold belts are emphasized in order to determine whether all putative variscan strain is indeed variscan in age new time temperature data vitrinite reflectance apatite fission track populations are discussed along with offshore data a case is then presented for recognizing quite distinct episodes of both variscan and post variscan heating and deformation some of the implications for the variscides to the east are briefly examined and the suitability of a regional escape tectonics model is tested

fault trace complexity cumulative slip and the shape of the magnitude frequency distribution for strike slip faults a global survey summary we examine whether the shape of the magnitude frequency distribution for strike slip faults is described by the gutenburg richter relationship log n a bm or by the characteristic earthquake model by analysing a data set of faults from california mexico japan new zealand china and turkey for faults within regional seismic networks curves of the form log n yrpl a bm where n yr is the number of events per year equal to magnitude m are fit to the instrumental record of seismicity and geological data are used to estimate independently the size and recurrence rate of the largest expected earthquakes that would rupture the total length of the fault extrapolation of instrumentally derived curves to larger magnitudes agrees with geological estimates of the recurrence rate of the largest earthquakes for only four of the 22 faults if uncertainties in curve slope are considered and significantly underestimates the geological recurrence rates in the remaining cases also if we predict the seismicity of the faults as a function of fault length and slip rate and the predicted seismicity is distributed in accord with the gutenburg richter relationship we find the predicted recurrence rate to be greater than the observed recurrence rates of smaller earthquakes along most faults if individual fault zones satisfy the gutenburg richter relationship over the long term our observations imply that during the recurrence interval of the largest expected earthquakes the recurrence of lesser sized events is not steady but rather strongly clustered in time however if the instrumental records provide an estimate of the long term rate of small to moderate earthquakes along the faults our observations imply that the faults generally exhibit a magnitude frequency distribution consistent with the characteristic earthquake model also we observe that the geometrical complexity of strike slip faults is a decreasing function of cumulative strike slip offset the four faults we observe to be consistent with the gutenburgrichter relationship are among those characterized by the least amount of cumulative slip and greatest fault trace complexity we therefore suggest that the ratio of the recurrence rate of small to large earthquakes along a fault zone may decrease as slip accumulates and the fault becomes smoother

magmato sedimentary carboniferous to jurassic evolution of the western tauern window eastern alps constraints from u pb zircon dating and geochemistry new geochronological u pb la icp ms zircon data and geochemical analyses from the variscan orthogneisses and metavolcanic rocks in the western tauern window are presented and used to reconstruct the pre alpine evolution of this area the late and post variscan stage in the tauern window was characterised by distinct magmatic pulses accompanied by the formation of volcano sedimentary basins the magmatic activity started in the visean 335 4 1 5 ma with the intrusion of a k rich durbachitic biotite granite protolith of the ahorn gneiss following a period of exhumation and erosion westfalian stefanian volcanics were deposited grierkar meta rhyodacite 309 8 1 5 ma venntal meta rhyolite 304 0 3 0 ma a renewed magmatic pulse occurred in the early permian producing large volumes of tonalites and granodiorites tux meta granodiorite 292 1 1 9 ma the youngest magmatism is characterised by pyroclastic and tuffitic deposits pfitsch meta rhyolite 280 5 2 6 ma schonach valley meta andesite 279 0 4 8 ma this volcanism was probably related to crustal extensional faulting within an intra continental graben and horst setting asthenospheric upwelling and heat flow increase due to the onset of the permian rifting the permo triassic peneplanation and subsidence is documented by shallow marine and evaporitic deposits probably in the middle jurassic times the area was flooded and in the late jurassic the whole area was covered by limestones representing post rift sediments on the southern european continental margin

a more precise chronology of earthquakes produced by the san andreas fault in southern california improved methods of radiocarbon analysis have enabled us to date more precisely the earthquake ruptures of the san andreas fault that are recorded in the sediments at pallett creek previous dates of these events had 95 confidence errors of 50 100 calendar years new error limits are less than 23 calendar years for all but two of the dated events this greater precision is due to larger sample size longer counting time lower background noise levels more precise conversion of radiocarbon ages to calendric dates and better stratigraphic constraints and statistical techniques the new date ranges with one exception fall within the broader ranges estimated previously but our estimate of the average interval between the latest 10 episodes of faulting is now about 132 years variability about the mean interval is much greater than was suspected previously five of the nine intervals are shorter than a century three of the remaining four intervals are about two to three centuries long despite the wide range of these intervals a pattern in the occurrence of large earthquakes at pallett creek is apparent in the new data the past 10 earthquakes occur in four clusters each of which consists of two or three events earthquakes within the clusters are separated by periods of several decades but the clusters are separated by dormant periods of two to three centuries this pattern may reflect important mechanical aspects of the fault s behavior if this pattern continues into the future the current period of dormancy will probably be greater than two centuries this would mean that the section of the fault represented by the pallett creek site is currently in the middle of one of its longer periods of repose between clusters and sections of the fault farther to the southeast are much more likely to produce the next great earthquake in california the greater precision of dates now available for large earthquakes recorded at the pallett creek site enables speculative correlation of events between paleoseismic sites along the southern half of the san andreas fault a history of great earthquakes with overlapping rupture zones along the mojave section of the fault remains one of the more attractive possibilities

tectonic evolution of the salton sea inferred from seismic reflection data the salton sea is an evolving pull apart basin located between the san andreas and imperial faults in southern california seismic and geological data reveal a rapidly subsiding southern sub basin that is bounded by a hinge zone to the north and northwest dipping normal faults to the south oblique extension across strike slip faults causes subsidence and leads to the formation of pull apart basins such as the salton sea in southern california the formation of these basins has generally been studied using laboratory experiments or numerical models1 2 3 4 here we combine seismic reflection data and geological observations from the salton sea to understand the evolution of this nascent pull apart basin our data reveal the presence of a northeast trending hinge zone that separates the sea into northern and southern sub basins differential subsidence 10 mm yr 1 in the southern sub basin suggests the existence of northwest dipping basin bounding faults near the southern shoreline which may control the spatial distribution of young volcanism rotated and truncated strata north of the hinge zone suggest that the onset of extension associated with this pull apart basin began after 0 5 million years ago we suggest that slip is partitioned spatially and temporally into vertical and horizontal domains in the salton sea in contrast to previous models based on historical seismicity patterns5 the rapid subsidence and fault architecture that we document in the southern part of the sea are consistent with experimental models for pull apart basins1

an isotopic and geochemical study of snowmelt runoff in a small arctic watershed old water contributions to snowmelt runoff in a stream can be defined as water which was stored in the catchment prior to the start of the runoff event in question we used mass balance techniques for natural oxygen 18 and several chemical parameters electrical conductivity ca and mg to estimate the magnitude and timing of old water contributions to snowmelt runoff in the apex river watershed during the 1983 field season the apex river catchment is located in the southern part of baffin island northwest territories canada the watershed has an area of 60 km2 it is in the zone of continuous permafrost and the geology is dominantly precambrian gneiss with sporadic thin glacial overburden the isotopic data indicate that for the snowmelt season of 1983 third highest peak discharge of 11 years of record approximately 50 per cent of the peak stream discharge consisted of old water our data also suggest that about 60 per cent of the entire 1983 hydrograph was old water the chemical parameters give old water contributions which are at least 10 per cent less than the isotopically derived estimate but they are consistent with the isotopic estimate during peak flow

irregular recurrence of large earthquakes along the san andreas fault evidence from trees old trees growing along the san andreas fault near wrightwood california record in their annual ring width patterns the effects of a major earthquake in the fall or winter of 1812 to 1813 paleoseismic data and historical information indicate that this event was the san juan capistrano earthquake of 8 december 1812 with a magnitude of 7 5 the discovery that at least 12 kilometers of the mojave segment of the san andreas fault ruptured in 1812 only 44 years before the great january 1857 rupture demonstrates that intervals between large earthquakes on this part of the fault are highly variable this variability increases the uncertainty of forecasting destructive earthquakes on the basis of past behavior and accentuates the need for a more fundamental knowledge of san andreas fault dynamics

slip on the elmore ranch fault during the past 330 years and its relation to slip on the superstition hills fault abstract the elmore ranch fault is a left lateral fault that strikes northeast within the right lateral transform boundary that strikes northwest through southern california it lies transverse and adjacent to the segment of the superstition hills fault that ruptured in 1987 rupture of the elmore ranch fault m s 6 2 preceded rupture of the superstition hills fault m s 6 6 by about 11 4 hr the elmore ranch fault slipped at the surface in 1987 with left lateral displacements of up to 130 mm geological data indicate that it had slipped prehistorically sometime after about 1660 a d probably in a single event excavations at three sites enable the following comparisons at these sites the only significant component of dip slip down to the southeast was found on the west strand for slip previous to 1987 the superstition hills fault has also been documented to have experienced one slip event between 1660 and 1987 thus these slip events on the elmore ranch and superstition hills faults may have occurred in a sequence similar to that in 1987 neither the main fault nor the cross fault however appear to have exactly duplicated their previous surficial slip previous slip was probably smaller on the superstition hills fault and larger on the elmore ranch fault zone than in the 1987 event because the temporal correlation between previous slip events is not proven rupture sequences other than a doublet in which main fault rupture follows cross fault rupture are possible

dating the onset of lgm ice surface lowering in the high alps abstract the general chronological outline of the last glacial maximum lgm in the alps is well known after more than two centuries of ice age research in europe current studies focus on resolving the details of the deglaciation process after the lgm particularly few data in this context are available from the high alps here we report chronological constraints on the onset of deglaciation in two different study areas from the western and eastern alps the mont blanc italy and zillertal alps austria we sampled 32 bedrock and boulder surfaces from high elevation ridges beneath the glacial trimline the oldest 10 be exposure ages of 18 5 ka correspond to the initiation of lowering of the lgm ice surface identical ages from both study areas suggest synchronous decay of the lgm glaciers in the accumulation zones of the western and eastern alps thus the high alpine ice surface lowered roughly synchronously to the downwasting of the glacier tongues in the forelands that was completed 19 18 ka in both study areas ages of numerous samples that are consistently 2 3 ka younger than 18 5 ka suggest the persistance of remnant ice patches at high elevations in the lateglacial accumulation zones approximately until the bolling allerod interstadial

temporal evolution of fault systems in the upper jurassic of the central german molasse basin case study unterhaching the structural evolution of faults in foreland basins is linked to a complex basin history ranging from extension to contraction and inversion tectonics faults in the upper jurassic of the german molasse basin a cenozoic alpine foreland basin play a significant role for geothermal exploration and are therefore imaged interpreted and studied by 3d seismic reflection data beyond this applied aspect the analysis of these seismic data help to better understand the temporal evolution of faults and respective stress fields in 2009 a 27 km2 3d seismic reflection survey was conducted around the unterhaching gt 2 well south of munich the main focus of this study is an in depth analysis of a prominent v shaped fault block structure located at the center of the 3d seismic survey two methods were used to study the periodic fault activity and its relative age of the detected faults 1 horizon flattening and 2 analysis of incremental fault throws slip and dilation tendency analyses were conducted afterwards to determine the stresses resolved on the faults in the current stress field two possible kinematic models explain the structural evolution one model assumes a left lateral strike slip fault in a transpressional regime resulting in a positive flower structure the other model incorporates crossing conjugate normal faults within a transtensional regime the interpreted successive fault formation prefers the latter model the episodic fault activity may enhance fault zone permeability hence reservoir productivity implying that the analysis of periodically active faults represents an important part in successfully targeting geothermal wells

evidence for late carboniferous subduction type magmatism in mafic ultramafic cumulates of the sw tauern window eastern alps hectometric bodies of fresh mafic ultramafic cumulates have been discovered within the central gneiss of the zillertal massif sw tauern window eastern alps italy the cumulates intruded by the central gneiss granitoids are amphibole bearing harzburgites and norites made of cumulitic olivine fo73 80 spinels sulphides and plagioclase an79 87 included in orthopyroxene en76 83 and ti pargasite mg 0 73 0 81 major and trace element geochemistry indicates that these rocks represent olivine spinel plagioclase cumulates in which interstitial melt crystallized as orthopyroxene ti pargasite the parental melt has trace element patterns typical of subduction zone magmas the crystallization sequence mineral compositions and modes indicate that cumulates formed from a h2o rich basaltic andesite which intruded at low pressure 2 kbar and temperatures of 1 050 1 100 c shrimp u pb dating of zircons from ultramafic cumulates and adjacent metagranodiorite yielded ages of 309 5 and 295 3 ma respectively in agreement with field relationships these results show that the mafic ultramafic cumulates represent a co genetic early product of the late carboniferous plutonic activity in the western tauern window which started in the westphalian earlier than previously thought our data on the most primitive rocks in the zillertal massif permit for the first time insight into the parental magma and thus into the origin of this late carboniferous calc alkaline magmatism which was most likely related to slab break off during the late variscan convergence

palaeontological and facial features of the upper jurassic hochstegen marble tauern window eastern alps micropalaeontological microscopic and mineralogical investigations of the ductily deformed and greenschist facies metamorphic hochstegen marble in the tauern window shed new light on its stratigraphy and fades new radiolarian and sponge spicule discoveries have been made in cherty limestone marbles they confirm previous age assignments and permit for the first time a more exact micropalaeontological age determination of early tithonian for the upper parts of the marble forty morphotypes of radiolarians could be distinguished in one sample a fisher diversity index of 6 is reached indicating deeper marine conditions the spicule fauna is also diverse and shows affinity to the s german malm in respect to all the data it can be presumed that carbonate sedimentation of the hochstegen marble took place in a deeper marine environment at the southern margin of the european continent helvetic realm during the whole late jurassic

interaction of permo triassic and jurassic extensional fault blocks during the development of the northern north sea the main structural elements resulting from late permian early triassic extension have been resolved across the total width of the northern north sea the northern segment of the basin north of 61 n bounded to the west by the hutton fault and to the east by the norwegian mainland was occupied by four westerly tilted half grabens 25 35 km in width prior to jurassic extension the central segment of the basin 60 20 61 n exhibits a full graben beneath the jurassic horda platform flanked by half grabens tilted towards the basin margins the change in permo triassic fault block configuration defining structural domains is largely constrained by a basement discontinuity which runs diagonally ne sw across the basin maximum jurassic extension is represented by several centres of subsidence aligned nne ssw across a n s oriented and broader permo triassic basin jurassic extension was concentrated within the viking graben proper south of 60 n which in this area is represented by single westerly tilted en echelon half graben segments 20 25 km wide the area affected by jurassic extension becomes progressively wider to the north again governed by the basement discontinuity eventually encompassing the total width of the basin c 200 km north of 61 n the central segment of the northern north sea displays the greatest contrast in permo triassic and jurassic structural styles and basin geometry jurassic stretching and faulting was negligible to the east horda platform precisely the area which had been the site of maximum permo triassic stretching and fault activity it has generally been assumed that jurassic fault configuration along the eastern margin of the central segment of the viking graben to a large extent reflects the reactivation of major permo triassic faults this study demonstrates the interference of permo triassic and jurassic basin geometries in this area due to major faults of the two generations dipping in opposite directions as a consequence the e tilted oseberg fault block of jurassic origin and c 20km in width is underlain by a wider c 35 km and w tilted permo triassic fault block

the wister mud pot lineament southeastward extension or abandoned strand of the san andreas fault we present the results of a survey of mud pots in the wister unit of the imperial wildlife area thirty three mud pots pot clusters or related geothermal vents hundreds of pots in all were identified and most were found to cluster along a northwest trending line that is more or less coincident with the postulated sand hills fault an extrapolation of the trace of the san andreas fault southeastward from its accepted terminus north of bombay beach very nearly coincides with the mud pot lineament and may represent a surface manifestation of the san andreas fault southeast of the salton sea additionally a recent survey of vents near mullet island in the salton sea revealed eight areas along a northwest striking line where gas was bubbling up through the water and in two cases hot mud and water were being violently ejected

slip along the superstition hills fault associated with the 24 november 1987 superstition hills california earthquake surficial slip along the entire mapped length of the superstition hills fault in southern california occurred in association with the superstition hills earthquake m s 6 6 of 24 november 1987 we made repeated measurements of surface slip at 36 sites along the fault and occupied 64 sites at least once at our sites dextral slip was as high as 48 5 cm 1 day after the earthquake and 71 cm 2 months after the measurements show that slip during the period from hr to several hundred hr following the event is described by a simple power law of time extrapolation to t 1 min indicates that co seismic slippage ranged from 5 to 23 cm at 10 of our best recorded sites suggesting that finite co seismic slippage occurred along the length of the fault these extrapolations are supported by a measurement made at imler road 30 min after the shock measurements are complete through october 1988 at many sites the form of slip rate was decay changed from power law to a function of log time during the interval between 300 and 500 hr after the earthquake logarithmic slip rate decay in time was observed for a period of several yr after the parkfield borrego mountain and imperial valley earthquakes those measurements may have begun too late to resolve power law behavior at early times if current logarithmic behavior of the superstition hills fault persists right lateral slippage will approach 90 cm 10 yr after the rupture changes in the along fault displacement profile correlate well with geometric features including a fault bend and a major fault step moreover slip behavior appears to be correlated to the thickness of sedimentary cover along the fault also the northern half of the fault is bounded by a large block of continental crystalline basement the presence of this block may have contributed to the relatively uniform early slip behavior observed there

behavior of the superstition hills fault during the past 330 years we have investigated the recent prehistoric behavior of the superstition hills fault by examining its effect on the beach deposits of ancient lake cahuilla excavation of these sediments in three dimensions where they are cut by the fault has enabled determination of total offset since the latest highstand of the lake about 330 years ago as of 3 march 1988 total dextral offset was 1106 50 mm about 609 mm of this amount can be attributed to one or more slip events before 1987 the remaining slip occurred during the moderate earthquake of 24 november 1987 and as subsequent aftercreep additional aftercreep here might produce a total of 1210 100 mm for that event thus if afterslip continues according to our prediction slip associated with the penultimate seismic slip event on the superstition hills fault was only about half of the co seismic slip and predicted afterslip associated with the 1987 earthquake this difference established at a single site on the fault may reflect a larger size for the 1987 event than for its predecessor we calculate that the slip rate of the superstition hills fault zone averaged over the past 330 years is between about 2 and at least 6 mm yr at this site during this time the average interval between large surface slip events on the superstition hills fault has been between about 150 and 300 years the pre 1987 slip event documented in our excavations could have occurred at any time between a d 1660 and about a d 1915 these results are significant for understanding earthquake recurrence and patterns of earthquakes in the imperial and coachella valleys

active tectonic studies in the united states 1987 1990 the techniques and instrumentation used in active tectonic studies are discussed and recent results are reviewed it is suggested that a critical mass of data on several particular regions has been accumulated making possible critical debates and attempts to assess earthquake hazards particular attention is given to studies of the pacific northwest region basin and range deformation studies and distributed deformation and hidden earthquake sources also included is a comprehensive bibliography for the period

the palaeozoic evolution in the alps from gondwana to pangea more than 50 of the alps expose fragments of palaeozoic basement which were assembled during the alpine orogeny although the tectonic and metamorphic history of the basement units can be compared to that of the variscan crust in the alpine foreland most of the basement pieces of the alps do not represent the direct southern continuation of variscan structural elements evident in the massif central the vosges black forest or the bohemian massif the basement units of the alps all originated at the gondwana margin they were derived from a precambrian volcanic arc suture fringing the northern margin of gondwana from which they were rifted during the cambrian ordovician and silurian a short lived ordovician orogenic event interrupted the general rifting tendency at the gondwana active margin after the ordovician the different blocks drifted from the gondwana margin to their pangea position colliding either parallel to armorica with laurussia or with originally peri gondwanan blocks assembled presently in armorica from the devonian onwards many basement subunits underwent the complex evolution of apparently oblique collision and nappe stacking docking started in the external massifs the penninic and lower and middle austroalpine units in approximately devonian early carboniferous times followed by the upper austroalpine and the south alpine domains in the visean and the namurian times respectively wrenching is probably the best mechanism to explain all syn and post collisional phenomena since the visean followed by post orogenic collapse and extension it explains the occurrence of strike slip faults at different crustal levels the formation of sedimentary troughs as well as the extrusion and intrusion of crustal and mantle derived magmas and allows for contemporaneous rapid uplift of lower crustal levels and their erosion from the stephanian onwards all regions were deeply eroded by large river systems

post variscan to early alpine sedimentary basins in the tauern window eastern alps the crystalline basement of the tauern window is locally covered by palaeozoic to mesozoic sediments that experienced alpine tectonometamorphism the sedimentary cover has been subdivided into mappable lithological units the correlation of these units the use of some dated marker intervals and independent palinspastic restoration provide evidence that the depositional area was differentiated into basins and swells at the end of the variscan orogeny during the carboniferous and permian intermontane basins formed in basement rocks and mainly continental clastics accumulated in elongate troughs later probably during the triassic there was levelling of the previous relief and subsidence of the basins but continental sedimen tation still prevailed although interrupted by some marine transgressions thereafter probably during the jurassic the area was progressively flooded and the sedimentation became increasingly calcareous the upper jurassic carbonates document complete submergence in some areas the upper jurassic carbonates directly rest on crystalline basement indicating renewed tectonic stretching the sedimentary cover shows striking similarities with coeval deposits within the germanic basin and the study area is therefore considered to have been part of the southern european continental margin of the tethys the so called vindelician land

rupture patterns and preshocks of large earthquakes in the southern san jacinto fault zone we relocated the large 1937 1942 and 1954 earthquakes in the san jacinto fault zone the epicenters of the main shocks aftershocks and some preshocks were determined using empirical station corrections from recent small events in the study areas the 1937 ml 5 9 earthquake has an epicenter between the surface traces of the san jacinto and buck ridge faults and aftershocks suggest about 7 km of rupture predominantly to the northwest a significant increase in small earthquake activity occurred about formula yr before this event the 1954 m l 6 2 earthquake is located at the southeast end of the mapped trace of the san jacinto fault and aftershocks suggest about 15 km of rupture further southeast into an area of folded young sediments with no surface fault trace this event was preceded by a cluster of small earthquakes which occurred within an 8 hr period 10 weeks before the main event and in the eventual rupture zone the 1942 m l 6 3 earthquake is located southwest of the southeast end of the coyote creek fault large aftershocks of this event are spread over a 15 by 18 km area southwest of the coyote creek fault and are not associated with any one fault the relation of the 1942 event to the san jacinto fault zone is not simple

relating collisional kinematics to exhumation processes in the eastern alps abstract based on a review of the surface and deep structure of the eastern alps we link the timing and the inferred displacement fields to exhumation of upper and lower crustal units of the orogenic nappe stack during collision the discussion focuses mainly on the tauern window and its country rocks the only area of the eastern alps where the orogenic wedge from its uppermost austroalpine nappes down to its deepest european basement nappes is continuously exposed we summarize and discuss the long standing controversy on the mechanisms of exhumation of this nappe stack on the base of a synthesis of structural and geochronological data and restorations of collisional displacements both in cross sections and map views we conclude that the large amounts of exhumation assessed for the western eastern alps resulted from large amounts of thickening and erosion not observed in the eastern part of the eastern alps extensional faults laterally bounding the area of major thickening and exhumation are inferred to nucleate in order to accommodate displacement around the indenter corner in the west and in order to reduce a large gradient of crustal thickness and surface elevation in the east restorations to the pre indentation stage document an amount of northward increasing orogen parallel extension varying 45 km to 85 km corresponding to 15 of extension that is partly accommodated along normal faults n s shortening between the northern calcareous alps and the dolomites indenter attained 75 km in the west and decreased to 30 km in the east 55 km out of these 75 were accommodated in the area of the tauern window our kinematic model shows that lateral extrusion accommodated along conjugate strike slip faults requires large amounts of north south shortening in the western part of the eastern alps such shortening is consistent with the reconstructed upright folding and erosion of the tauern window thus explaining the largest amount of its exhumation in contrast the eastern termination of the eastern alps represents an area where collisional convergence was barely accommodated by crustal thickening this transition from a highly shortened thickened and exhumed wedge in the west mainly affected by orogen perpendicular displacements to a barely shortened and exhumed wedge in the east mainly characterised by orogen parallel displacements spatially coincides with a change in the deep structure of the european slab indeed the inferred continental european slab imaged in the west disappears into a low velocity anomaly where no slab is detected in the east an inherited step in the geometry in map view of the european passive margin causing its crust to enter the subduction zone earlier than the area east of the tauern window may explain the rapid decrease of shortening of thickening the different syn collisional p t gradients and the disappearance of the continental slab east of the katschberg fault

hydrology of two slopes in subarctic yukon canada two subarctic forested slopes in central wolf creek basin yukon were studied in 1996 1997 to determine the seasonal pattern of the hydrologic processes a south facing slope has a dense aspen forest on silty soils with seasonal frost only and a north facing slope has open stands of black spruce and an organic layer on top of clay sediments with permafrost snowmelt is advanced by approximately one month on the south facing slope due to greater radiation receipt meltwater infiltrates its seasonally frozen soil with low ice content recharging the soil moisture reservoir but yielding no lateral surface or subsurface flow summer evaporation depletes this recharged moisture and any additional rainfall input at the expense of surface or subsurface flow the north facing slope with an ice rich substrate hinders deep percolation snow meltwater is impounded within the organic layer to produce surface runoff in rills and gullies and subsurface flow along pipes and within the matrix of the organic soil during the summer most subsurface flows are confined to the organic layer which has hydraulic conductivities orders of magnitudes larger than the underlying boulder clay evaporation on the north facing slope declines as both the frost table and the water table descend in the summer a water balance of the two slopes demonstrates that vertical processes of infiltration and evaporation dominate moisture exchanges on the south facing slope whereas the retardation of deep drainage by frost and by clayey soil on the permafrost slope promotes a strong lateral flow component principally within the organic layer these results have the important implication that permafrost slopes and organic horizons are the principal controls on streamflow generation in subarctic catchments copyright 1999 john wiley sons ltd

surface ruptures on cross faults in the 24 november 1987 superstition hills california earthquake sequence left lateral slip occurred on individual surface breaks along northeast trending faults associated with the 24 november 1987 earthquake sequence in the superstition hills imperial valley california this sequence included the m s 6 2 event on a left lateral northeast trending cross fault between the superstition hills fault shf and brawley seismic zone which was spatially associated with the left lateral surface breaks six distinct subparallel cross faults broke at the surface with rupture lengths ranging from about formula to 10 km and maximum displacements ranging from 30 to 130 mm about half a day after the m s 6 2 event an m s 6 6 earthquake nucleated near the intersection of the cross faults with the shf and rupture propagated southeast along the shf whereas right lateral slip on the shf occurred dominantly on a single trace in a narrow zone the cross fault surface slip was distributed over several stands across a 10 km wide zone also whereas afterslip accounted for a large proportion of total slip on the shf there is no evidence for afterslip on the cross faults we present documentation of these surface ruptures a simple mechanical model of faulting illustrates how the foreshock sequence may have triggered the main rupture displacement on other cross faults could trigger an event on the southern san andreas fault by a similar mechanism in the future