core evidence of paleoseismic events in paleogene deposits of the shulu sag in the bohai bay basin east china and their petroleum geologic significance abstract the shulu sag located in the southwestern corner of the jizhong depression bohai bay basin of east china is a ne sw trending elongate cenozoic half graben basin the lowermost part of the third member of the shahejie formation in this basin is characterized by continental rudstone and calcilutite to calcisiltite facies based on core observation and regional geologic analysis seismites are recognized in these lacustrine deposits which include soft sediment deformation structures sedimentary dikes hydraulic shattering diapir structures convolute lamination load flame structures ball and pillow structures loop bedding and subsidence structures synsedimentary faults and seismoturbidites in addition mixed source rudstones consisting of the paleozoic carbonate clasts and in situ calcilutite clasts in the lowermost submember of shahejie 3 appear in the seismites suggesting an earthquake origin a complete representative vertical sequence in the lowermost part of the third member found in well st1h located in the central part of the shulu sag shows from the base to the top underlying undeformed layers synsedimentary faults liquefied carbonate rocks allogenetic seismoturbidites and overlying undeformed layers seismites are widely distributed around this well and there are multiple sets of stacked seismites separated by undeformed sediment the nearby nw trending taijiazhuang fault whose fault growth index is from 1 1 to 1 8 and the nne trending xinhe fault with a fault growth index of 1 3 1 9 may be the source of the instability to create the seismites these deformed sedimentary layers are favorable for the accumulation of oil and gas for example sedimentary dikes can cut through many layers and serve as conduits for fluid migration sedimentary faults and fractures induced by earthquakes can act as oil and gas migration channels or store petroleum products as well seismoturbidites and mixed source rudstones are excellent reservoirs due to their abundant primary or dissolved pores

planetary and tidal wave type oscillations in the ionospheric sporadic e layers over tehran region 1 it is believed that in the lower ionosphere particularly in the ionospheric sporadic e es layers 90 130 km the planetary and tidal wave type oscillations in the ionized component indicate the planetary and tidal waves in the neutral atmosphere in the present work the presence of wave type oscillations including planetary and tidal waves in the ionospheric sporadic e layers over tehran region is examined data measured by a digital ionosonde at the ionospheric station of the institute of geophysics university of tehran from july 2006 to june 2007 are used to investigate seasonal variations of planetary and tidal waves activities for the purpose of accurate comparison between different seasons wavelet transform is applied to time series of foes and h es namely the critical frequency and virtual height of es layers respectively the results show that the sporadic e layers over tehran region are strongly under the influence of upward propagation of waves from below more specifically among diverse range of periodicities in the sporadic e layers we found that diurnal 24 hours and semidiurnal 12 hours oscillations in all seasons for both parameters moreover terdiurnal 8 hours tide like variation is observed during spring and summer for foes parameter and summer and winter for h es furthermore the results show that diurnal tidal waves obtain their maximum activities during autumn and winter seasons and their activities decrease during the late spring and summer in addition periods of about 2 4 6 10 14 and 16 days in our observation verifies the hypothesis of upward propagation of planetary waves from lower atmosphere to the ionosphere moreover planetary waves have their maximum activities during equinox

sedimentary features of the seismo turbidites lake biwa japan abstract seismo turbidite layers are deposited at the foot of the steep slope of the half graben in which lake biwa has accumulated sedimentary studies especially of grain size distribution of selected turbidites provide excellent information for clarifying the distinctive features of general seismo turbidites development of the two constituent sublayers lower sandy sublayer and upper silt sublayer lack or limited appearances of traction indicating structures and characteristic grain size distribution in the two constituent sublayers are most remarkable and significant the characteristic grain size distribution features are coarse tail grading in a relatively thick sandy sublayer exceptionally rapid distribution grading through the thin boundary interval between the two sublayers height increase and fluctuation of the silt mode and high clay content brief discussion was made on the causes of these sedimentary features the need and importance of further comparative studies of various turbidites known triggering forces are emphasized

large scale seismically induced mass movements in a former glacial lake basin lake temiscouata northeastern appalachians eastern canada abstract disturbed lacustrine deposits of eastern canada have been associated with past seismic events in the intraplate western quebec seismic zone wqz and the charlevoix kamouraska seismic zone cksz with five major earthquakes that occurred during historical times and hundreds of minor earthquakes the cksz is the most active seismic zone in eastern canada here we present new high resolution multibeam bathymetric subbottom profiler and sediment core data collected in lake temiscouata southeastern quebec the largest lake located within the influence of the cksz the occurrence of mass movements in the highly cohesive glaciolacustrine deposits of the lake produced a peculiar lacustrine landscape consisting of steep slide scars and residual mounds and very narrow residual crests our data indicate that postglacial times were marked by recurrent seismically induced mass movement events that cannot be individually identified in the sedimentary record due to the highly disturbed stratigraphy of the lake and to the absence of significant postglacial background sediments between events the most recent recorded mass movement is a distinct debris flow sediment layer on the lake floor that was deposited at 1300 cal bp very shortly after a distinct large scale mass movement event observed across the entire lake basin the presence of silt layers in gyttja overlying these disturbed units suggests that the region was affected by other seismic events following this event although no mmds could be directly related to these layers

modelling seismites with a digital shaking table abstract soft sediment deformation structures induced by seismically triggered liquefaction and or fluidization seismites have been reproduced with a digital shaking table we have used natural sediments with variable granulometric ranges clay silt and sand and an earthquake simulator that is able to reproduce real tridimensional seismograms acceleration and pore pressure recording allowed us to follow liquefaction and or fluidization processes in unconsolidated sediments during earthquakes different types of seismites were produced by variations in the tested sedimentary column

an explanation for the seasonal dependence of midlatitude sporadic e layers 1 the midlatitude sporadic e layers form when metallic ions of meteoric origin in the lower thermosphere are converged vertically in a wind shear the occurrence and strength of sporadic e follow a pronounced seasonal dependence marked by a conspicuous summer maximum although this is known since the early years of ionosonde studies its cause has remained a mystery as it cannot be accounted for by the windshear theory of e s formation we show here that the marked seasonal dependence of sporadic e correlates well with the annual variation of sporadic meteor deposition in the upper atmosphere the later has been established recently from long term measurements using meteor radar interferometers in the northern and southern hemispheres knowing that the occurrence and strength of sporadic e layers depends directly on the metal ion content which apparently is determined primarily by the meteoric deposition the present study offers a cause and effect explanation for the long going mystery of sporadic e layer seasonal dependence

seismites from a well core of palustrine deposits as a tool for reconstructing the palaeoseismic history of a fault abstract the concud fault is located at the junction between the jiloca and teruel grabens central eastern iberian chain spain the late pleistocene activity of this fault has been well logged from structural and palaeoseismological trench studies but only scattered data of the late pliocene seismic activity exist the late pliocene early pleistocene syn tectonic infill consists of an endorheic continental succession in which a 75 m long continuous well was drilled near the concud fault along the entire well core several types of soft sediment deformation structures with variable morphology size and frequency have occurred including clastic dykes load structures and slumps the rigorous analysis of the deformation structures their relationships with the involved sedimentary facies and the discrimination of possible deformation mechanisms and trigger processes allow us to interpret part of them as seismically induced structures the recognition of 21 deformed beds seismites allow the late pliocene early pleistocene seismic history of the concud fault to be reconstructed therefore 21 seismic events with m 5 and an apparent recurrence period of about 45 ka have been inferred

evidence of a role for modulated atmospheric tides in the dependence of sporadic e layers on planetary waves 1 a large amplitude 7 day period westward propagating s 1 planetary wave pw of global response has been reported from ground radar and satellite wind measurements in the mesosphere lower thermosphere mlt during the second half of august and well into september 1993 following recent suggestions that pw might play a role in the formation of midlatitude sporadic e layers es haldoupis and pancheva 2002 found a strong 7 day periodicity present in all stations concurrently with the 7 day planetary wave reported elsewhere by analyzing sporadic e critical frequency foes time series from eight midlatitude ionosonde stations covering a longitudinal zone from about 58 e to 157 w this study provided the first direct proof in favor of a pw role on es formation in the present paper we further investigate this role by considering the same pw event and correlating the 7 day periodicity in foes directly with concurrent variations in the mesospheric neutral wind measured with atmospheric radars in saskatoon canada and in sheffield united kingdom although our analysis cannot exclude a direct pw role on es formation it shows clearly that es is affected indirectly by the pw through the action of the diurnal and semidiurnal tides which are strongly modulated by the same pw apparently through a nonlinear interaction process at altitudes below 100 km this 7 day pw modulation was found to be clearly present simultaneously in the amplitude of the zonal 12 hour tidal wind the meridional 24 hour tidal wind and in both the 12 hour and 24 hour periodicities which existed in the foes time series the results here provide a new physical explanation for the observed relation between sporadic e layers and planetary waves

vertical coupling from the lower atmosphere to the ionosphere observations inferred from indian mst radar gps radiosonde ionosonde magnetometer olr noaa and saber timed instrument over gadanki

evidence of late glacial paleoseismicity from submarine landslide deposits within lac dasserat northwestern quebec canada abstract an integrated seismo and chronostratigraphic investigation at lac dasserat northwestern quebec identified 74 separate failures within eight event horizons horizons e and b and h and g have strong or moderately strong multi landslide signatures respectively composed of 11 23 failures while horizons f d c and a have minor landslide signatures consisting of a single or pair of deposit s cores collected at six sites recovered glacial lake ojibway varve deposits that are interbedded with the event horizons the correlation of the varves to the regional timiskaming varve series allowed varve ages or ranges of varve ages to be determined for the event horizons horizons h g e and b are interpreted to be evidence of paleoearthquakes with differing levels of interpretative confidence based on the relative strength of the multi landslide signatures the correlation to other disturbed deposits of similar age in the region and the lack or possibility of alternative aseismic mechanisms the four interpreted paleoearthquakes occurred between 9770 200 and 8470 200 cal yr bp when glacial lake ojibway was impounded behind the laurentide ice sheet during deglaciation they probably represent an elevated period of seismicity at deglaciation that was driven by crustal unloading

3000 year paleoseismological record from the region of the 1988 saguenay quebec earthquake abstract the 1988 magnitude m b 5 9 m blg 6 5 saguenay quebec earthquake occurred in a region considered to be aseismic but the epicenter was less than 100 km northwest of the seismically active region of charlevoix lake sediment cores representing some 3000 yr of sediment accumulation contain abnormal silt layers attributed to seismic shaking events prior to the 1988 earthquake the layers are formed by the relatively rapid settling of the silt portion of the seismically resuspended organic rich sediment cores were obtained over a distance of 120 km perpendicular to the saguenay graben structure several silt layers are much thicker and more widely distributed than the effect of the 1988 earthquake and are comparable to those observed at charlevoix that were produced by magnitude 6 to 7 events the silting events do not correlate between the sampled lakes nor does the pattern match that at charlevoix so that the shaking events are interpreted to be of local origin the recurrence interval for magnitude 6 earthquakes ranges from 350 to 1000 yr in contrast to the roughly 75 yr historical recurrence of earthquakes of magnitude greater than 6 at charlevoix

paleoseismological evidence from lake sediments for recent movement on the denali and other faults yukon territory canada abstract most of the pacific north america plate motion in northwestern canada and southeastern alaska occurs along coastal faults that are the inland extension of the queen charlotte dextral transform fault more ancient faults farther east such as the denali and duke river faults exhibit moderate earthquake activity and may be accommodating part of the pacific plate motion paleoseismological results based on seismic resuspension of lake sediments covering a period of up to 3000 years show that the seismicity on the denali duke river fault system is remarkably recent spanning just the last three to five centuries there is a northerly trending zone of seismicity from the active fairweather contact fault system on the coast across to the part of the denali fault that is currently as well as prehistorically active this partial transfer eastward of pacific plate motion may be analogous to a similar proposed transfer of motion northward to the denali fault from the same fairweather contact fault system farther west in alaska

sedimentary record of seismic events in the eocene green river formation and its implications for regional tectonics on lake evolution bridger basin wyoming abstract outcrops and cores from the top of the lacustrine tipton member and the base of the wilkins peak member 51 5 ma of the eocene green river formation bridger basin in southwestern wyoming yield a wide variety of sedimentary deformation features many of which are laterally extensive for more than 50 km they include various types of folds load structures pinch and swell structures microfaults breccias and sedimentary dikes in most cases deformation is represented by hybrid brittle ductile structures exhibiting lateral variation in deformation style these occur in low energy profundal organic rich carbonate mudstones oil shales trona beds tuffs and profundal to sublittoral silty carbonate deposited in paleolake gosiute the deformation is not specific to the depositional environment because sedimentary units stratigraphically higher with similar facies show no deformation the studied interval lacks any evidence for possible trigger mechanisms intrinsic to the depositional environment such as strong wave action rapid sediment loading evaporite dissolution and collapse or desiccation so endogenic causes are ruled out thus the deformation features are interpreted as seismites and change in deformation style and inferred increase in intensity towards the south suggest that the earthquakes were sourced from the nearby uinta fault system the 22 levels exhibiting seismites recognized in cores indicate earthquakes with minimum magnitudes between 6 and 7 minimum epicentral intensity mcs of 9 and varying recurrence intervals in the seismic history of the uinta fault system with a mean apparent recurrence period of 8 1 k y using average sedimentation rates and dated tuffs in detail however there are two noticeably active periods followed by relative quiescence the stratigraphic position of these deformed intervals also marks the transition between two distinct stages in lake evolution from the balanced filled tipton member to the overlying underfilled wilkins peak member thus these seismites are evidence for regional scale changes in lacustrine sedimentation of eocene lake gosiute in response to syndepositional tectonic activity analysis of synsedimentary deformation features is therefore a promising yet under utilized tool to trace the tectonic evolution of lacustrine deposits of the green river formation and other tectonically active marine and non marine basins

lake sediments record high intensity shaking that provides insight into the location and rupture length of large earthquakes on the alpine fault new zealand abstract understanding the seismic hazard posed by large earthquakes requires paleoseismic investigation because most faults have not ruptured repeatedly during the period of historic records however determining the location and length of fault ruptures using paleoseismic data remains challenging our study demonstrates that lake sediments record the high intensity shaking that occurs proximal to fault rupture allowing the location and length of ruptures to be reconstructed in two lakes adjacent to the alpine fault new zealand seismic shaking is recorded as subaqueous mass wasting derived turbidites formed by coseismic subaqueous slope failures which are overlain by sets of hyperpycnites representing elevated fluvial sediment fluxes from earthquake induced landslides precise radiocarbon age models show that shaking events are synchronous between the two lake sites and correlate with the timing of known alpine fault earthquakes modelled shaking intensities for the last two alpine fault earthquakes show that subaqueous mass wasting occurs when shaking intensities exceed modified mercalli scale mm vi vii and that fluvial sediment fluxes from earthquake induced landslides occur when shaking intensities exceed mm ix the data demonstrate that lake records distinguish between strong mm vi and violent mm ix shaking at a lake site the ability to map the spatial extent of mm ix shaking provides new insights into the timing and extent of rupture for the last five earthquakes on the alpine fault the study demonstrates that lake deposits constrain the spatial extent of rupture during large earthquakes and may yield long records of the spatial and temporal patterns of fault rupture

impact of the 1960 major subduction earthquake in northern patagonia chile argentina abstract the recent sedimentation processes in four contrasting lacustrine and marine basins of northern patagonia are documented by high resolution seismic reflection profiling and short cores at selected sites in deep lacustrine basins the regional correlation of the cores is provided by the combination of 137cs dating in lakes puyehue chile and frias argentina and by the identification of cordon caulle 1921 22 and 1960 tephras in lakes puyehue and nahuel huapi argentina and in their catchment areas this event stratigraphy allows correlation of the formation of striking sedimentary events in these basins with the consequences of the may june 1960 earthquakes and the induced cordon caulle eruption along the liquine ofqui fault zone lofz in the andes while this catastrophe induced a major hyperpycnal flood deposit of ca 3 106 m3 in the proximal basin of lago puyehue it only triggered an unusual organic rich layer in the proximal basin of lago frias as well as destructive waves and a large sub aqueous slide in the distal basin of lago nahuel huapi a very recent mega turbidite in the two distal basins of reloncavi fjord located close to the lofz suggests that 1960 co seismic movements in this area may have triggered the remobilization of ca 187 106 m3 of marine sediments

recent clastic sedimentation processes in lake puyehue chilean lake district 40 5 s clastic sedimentation processes in lake puyehue 40 5 s 72 5 w chile are described based on correlation of high resolution seismic profiles and multidisciplinary analysis of short sediment cores from two contrasting coring sites pu i and pu ii two main sedimentary environments are recognized in this oligotrophic lake i a proximal one which includes the delta of the main tributary the golgol river and is a deep flat basin with a ponded geometry and limited acoustic penetration and ii a distal one that is composed of several sub basins highlighting a drape geometry and better acoustic penetration based on the correlation of seismic data and sediment cores dated by radionuclides and the identification of tephra layers rininahue1907 cordon caulle 1921 22 and 1960 we argue that clastic sedimentation results essentially from the development of homopycnal flows at the end of the winter season in this monomictic lake whereas distal clastic environments pu ii coring site are dominated by biogenic production and appear to have been little affected by the 1960 chilean earthquake mw 9 5 and nearby volcanic eruptions this may not be the case for more proximal clastic environments pu i coring site which also experience sporadic hyperpycnal flows during major flood events in may june 1960 for example as several earthquake triggered landslides dammed the course of the golgol river and ca 7 106 m3 of volcaniclastic sediments fell over the drainage basin of the lake during the earthquake induced puyehue cordon caulle eruption successive outbursts in the golgol valley induced a mega flood in lake puyehue this hyperpycnal flow reworked a mixture of volcaniclastic and regolith derived sediments from the catchment as well as lacustrine sediments surrounding the golgol delta during the rising limb of the flood these recently reworked sediments are strikingly enriched in excess 210pb activity suggesting that positive anomalies in the activity of this isotope can be used to determine the source area of clastic sediments

flood and earthquake disturbance of 210pb geochronology lake anterne nw alps dating recent lake sediment records yielding disturbed 210pb profiles has been a problem of wide interest in palaeoclimatic and palaeoseismic studies over the last few centuries when applied to an alpine lake sedimentary record a high resolution sedimentological study reveals that the 210pb profile is disturbed by the occurrence of single event deposits triggered by two different mechanisms flood events deposits and gravity reworking removing disturbed layers from the 210pb profile yields a logarithmic depth activity relationship using a simple 210pb decay model cfcs provides an assessment of mean accumulation rate of continuous sedimentation as opposed to event linked sedimentation the correlation of the thickest four gravity reworked deposits with historically known earthquakes permits both validation and refinement of the age depth relationship this refinement highlights variations in accumulation rate consistent with post little ice age climatic variations

a semi empirical model of the contribution from sporadic meteoroid sources on the meteor input function in the mlt observed at arecibo 1 in this paper we present a modeling and observational study of the micrometeor input function with a focus on understanding how each of the extraterrestrial sporadic meteoroid sources contributes to the observed meteoric flux in the mesosphere and lower thermosphere mlt atmospheric region for this purpose we expand the model presented by janches et al 2006 using a monte carlo technique and incorporating 1 a widely accepted global mass flux which is divided into different proportions among the known sporadic meteoroid sources as the initial input above earth s atmosphere 2 contemporary knowledge on the source s velocity and radiant distributions and 3 the full integration of the canonical meteor equations that describe the meteoroid entry and ablation physics in addition we constrain the initial input through a comparison of our modeled results with meteor observations obtained with the 430 mhz high power and large aperture hpla arecibo radar in puerto rico that covers all seasons the predicted meteor rates and velocity distributions are in excellent agreement with the observed ones without the need for any additional normalization factor our results indicate that although the earth s apex centered radiant source which is characterized by high geocentric speeds 55 km s appears to be 33 of the meteoroids in the solar system at 1 au it accounts for 60 of the meteors observed by the arecibo hpla radar in the atmosphere the remaining 40 of observed meteors originate mostly from the helion and anti helion sources with a very small but constant during the day contribution of the south and north toroidal sources these results also suggest that particles smaller than 10 3 g with slow velocities 30 km s will not significantly ablate and never become observable meteors the motivation of this effort is to construct a new and more precise mif model needed for the subsequent modeling of the atmospheric phenomena related to the meteoric flux

a sporadic layer in the venus lower ionosphere of meteoric origin 1 the venus express radio science vera experiment aboard venus express has detected by means of radio occultation distinct low lying layers of electron density below the base 115 km altitude of the ionosphere of venus a plausible origin of these lowest layers is ionization by the influx of meteoroids into the atmosphere the layers appeared only occasionally during the 2006 and 2007 venus express occultation seasons could be identified only on the dayside and seem to be geographically localized as they usually occur in either the northern or southern hemisphere of the same orbit they are detected at all latitudes but only at solar zenith angles between 55 and 90 typical peak plasma densities of 1010 m 3 are reached between 110 and 120 km altitude peak meteor layer electron densities increase with decreasing solar zenith angle layer shapes are symmetric with respect to peak altitude the present observational statistics and lack of dedicated models prevents definite statements to be made on the origin of the source meteoroids

sedimentary features of seismoturbidites triggered by the 1983 and older historical earthquakes in the eastern margin of the japan sea abstract both mass failure deposits and turbidites are widely distributed in the epicentral area of the 1983 earthquake mw 7 9 in the eastern margin of the japan sea this basin is semi enclosed with no active conduits for the entrance of coarse detrital sediments seismic reflection surveys and sediment cores reveal that mass failure deposits which are distributed on the continental slopes merge into turbidites in the basin plain hence the mass wasting process is a major transportation process in this region one gravity core gh93 816 was recovered from the southeastern margin of the japan basin close to the epicentral area of the 1983 japan sea earthquake sedimentological results show that five turbidite beds are intercalated in the top 68 cm of the column occurrence of the b tm tephra at the depth of 68 71 cm indicates that these turbidite beds were developed during the last 1000 years the high 137cs concentration in the top 20 cm of the core implies that the uppermost turbidite bed was deposited after 1954 based on these age limits for the top and the bottom of the studied interval we estimate the recurrence intervals of turbidites as 160 330 years we suggest that these turbidites were generated by submarine slides which were triggered by the 1983 and older historical earthquakes in this region these seismoturbidites are characterized by amalgamated beds irregular structure sequences grain size breaks fluctuations abrupt changes in composition within bed and variable composition among beds from these features we infer that deposition resulted from a series of turbidity currents associated with multiple or line sources for example multiple shallow slides that were regionally initiated by the same earthquake the sedimentary features described herein may be useful as criteria for identifying modern seismoturbidites in other settings as well as seismoturbidites in the geologic record however further study is needed for the distinction of this type of turbidites from other types e g tempestites reflected turbidites

reconstruction of the holocene seismotectonic activity of the southern andes from seismites recorded in lago icalma chile 39 s abstract south central chile is one of the most geodynamically active areas in the world characterized by frequent volcanic eruptions and numerous earthquakes which are both recorded in lake sediments in lago icalma 39 s long piston and short gravity coring as well as 3 5 khz high resolution seismic profiling have been carried out in order to study the holocene sedimentary infill of the lake with a special focus on earthquake triggered deposits macroscopic description of sediment cores and detailed grain size analyses allow us to identify four types of seismically induced deposits or seismites slump deposits chaotic deposits turbidites s s and homogenites homogenites are characterized by the occurrence of three distinct units on grain size profiles i e a coarse base a thick homogeneous unit topped by a thin layer of very fine sediment and by the typical distribution of the grain size parameters in a skewness sorting diagram while turbidites s s are characterized by a continuous fining upward trend radiocarbon 210pb dating and tephrochronology allow us to demonstrate that the regional seismotectonic activity was probably very high between 2200 and 3000 cal years bp as well as between 7000 and 8000 cal years bp and that none of the historically documented earthquakes has triggered a seismite in lago icalma the most recent seismite recognized in the sediments of lago icalma is a slump deposit dated at 1100 100 ad i e older than the period covered by historical records the remarkable record of seismites between 2200 and 3000 cal years bp is probably influenced by a major eruption of sollipulli volcano at 3000 cal years bp which has rejuvenated the stock of terrigenous particles available for erosion by depositing a thick layer of pumices all over the watershed of lago icalma and by clearing the vegetation covering the volcanic ash soils this paper demonstrates that the record of seismically triggered deposits in lake sediments is not only controlled by the intensity of the triggering earthquake and the occurrence of unstable sediment along the lake slopes but also by the presence of particles available for erosion remobilisation in the watershed

6600 years of earthquake record in the julian alps lake bohinj slovenia sequences of lake sediments often form long and continuous records that may be sensitive recorders of seismic shaking a multi proxy analysis of lake bohinj sediments associated with a wellconstrained chronology was conducted to reconstruct holocene seismic activity in the julian alps slovenia a seismic reflection survey and sedimentological analyses identified 29 homogenite type deposits related to mass wasting deposits the most recent homogenites can be linked to historical regional earthquakes i e 1348 ad 1511 ad and 1690 ad with strong epicentral intensity greater than damaging viii on the medvedev sponheuer karnik scale the correlation between the historic earthquake dataset and the homogenites identified in a core isolated from local stream inputs allows interpretation of all similar deposits as earthquake related this work extends the earthquake chronicle of the last 6600 years in this area with a total of 29 events recorded the early holocene sedimentary record is disturbed by a seismic event 6617 94 yr cal bp that reworked previously deposited sediment and led to a thick sediment deposit identified in the seismic survey the period between 3500 to 2000 yr cal bp is characterized by a major destabilization in the watershed by human activities that led to increases in erosion and sedimentation rates this change increased the lake s sensitivity to recording an earthquake earthquake sensitivity threshold index with the occurrence of 72 turbidite type deposits over this period the high turbidite frequency identified could be the consequence of this change in lake earthquake sensitivity and thus these turbidites could be triggered by earthquake shaking as other origins are discarded this study illustrates why it is not acceptable to propose a return period for seismic activity recorded in lake sediment if the sedimentation rate varies significantly

southern argentina agile meteor radar system design and initial measurements of large scale winds and tides 1 the southern argentina agile meteor radar saamer was installed at rio grande on tierra del fuego 53 8 s 67 8 w in may 2008 and has been operational for 24 months this paper describes the motivations for the radar design and its placement at the southern tip of south america its operating modes and capabilities and observations of the mean winds planetary waves and tides during its first 20 months of operation saamer was specifically designed to provide very high resolution of large scale motions and hopefully enable direct measurements of the vertical momentum flux by gravity waves which have only been possible previously with dual or multiple beam radars and lidars or in situ measurements saamer was placed on tierra del fuego because it was a region devoid of similar measurements the latitude was anticipated to provide high sensitivity to an expected large semidiurnal tide and the region is now recognized to be a hot spot of small scale gravity wave activity extending from the troposphere into the mesosphere and lower thermosphere perhaps the most dynamically active location on earth saamer was also intended to permit simultaneous enhanced meteor studies including head echo and nonspecular measurements which were previously possible only with high power large aperture radars initial measurements have defined the mean circulation and structure exhibited planetary waves at various periods and revealed large semidiurnal tide amplitudes and variability with maximum amplitudes at higher altitudes often exceeding 60 m s 1 and amplitude modulations at periods from a few to 30 days

glacio seismotectonics ice sheets crustal deformation and seismicity abstract the last decade has witnessed a significant growth in our understanding of the past and continuing effects of ice sheets and glaciers on contemporary crustal deformation and seismicity this growth has been driven largely by the emergence of postglacial rebound models pgm constrained by new field observations that incorporate increasingly realistic rheological mechanical and glacial parameters in this paper we highlight some of these recent field based investigations and new pgms and examine their implications for understanding crustal deformation and seismicity during glaciation and following deglaciation the emerging glacial rebound models outlined in the paper support the view that both tectonic stresses and glacial rebound stresses are needed to explain the distribution and style of contemporary earthquake activity in former glaciated shields of eastern canada and fennoscandia however many of these models neglect important parameters such as topography lateral variations in lithospheric strength and tectonic strain built up during glaciation in glaciated mountainous terrains glacial erosion may directly modulate tectonic deformation by resetting the orogenic topography and thereby providing an additional compensatory uplift mechanism such effects are likely to be important both in tectonically active orogens and in the mountainous regions of glaciated shields in general the short term response to ice fluctuations is similar to the earth s response to fluctuations in water reservoirs with the subsequent increase or decrease in seismicity which depends on the pre existing stress state when the ice fluctuations occur on the spatial scale and magnitude of the late pleistocene glaciation and deglaciation however the viscoelastic response of the earth especially the mantle causes significant changes in crustal deformation and earthquake activity that is spatially extensive and temporally complex the regions of greatest ice thickness and the regions marginal to the late pleistocene ice sheets indicate the most dramatic evidence of earthquake faulting the mantle response to these large ice mass fluctuations and the change in mass between the oceans and land caused and continues to cause measureable crustal deformation at hundreds of kilometres from the ice margins for both tectonically active and cratonic regions palaeoseismic investigations of late pleistocene and holocene faults are an important tool in evaluating earthquake hazard the predicted response of the earth over this time however is very dependent on the model assumed for most regions far more carefully designed field observations are needed to constrain the existing rheological and ice models

tidal analysis of meridional winds at the south pole using a vhf interferometric meteor radar 1 atmospheric tides are perturbations driven by the periodic absorption of solar radiation they manifest themselves everywhere in the atmosphere and an understanding of their sources propagation and interaction with other waves is vital to comprehend the global atmosphere in order to measure the horizontal wind field in the mesosphere lower thermosphere mlt over the geographical south pole and use these measurements to understand the large scale dynamics of this region a vhf meteor radar was installed at the amundsen scott station at the south pole in 2001 the radar operated for a few months in 2001 and with minor interruptions in 2002 and 2003 however toward the end of 2003 receiver problems caused a drop in our meteor echo rates preventing us from getting tidal results after october 2003 we report on the temporal behavior of the diurnal and semidiurnal tides observed in the meridional wind field at mesospheric and lower thermospheric heights in the vicinity of the geographic south pole with the interferometric capabilities of this radar we also document for the first time the vertical structure of these tides the zonal wave number one component of the diurnal tide shows consistency for all years that we analyze on the other hand the zonal wave number one component of the semidiurnal tide shows significantly more year to year variability our results are compared to previous observations and model predictions a significant decrease in the amplitude of this oscillation from december 2002 to february 2003 is also observed and discussed

late quaternary morphostratigraphy of lake st joseph southeastern canadian shield evolution from a semi enclosed glacimarine basin to a postglacial lake abstract this paper reports and describes multibeam echosounder subbottom profiler and sediment sampling data collected in lake st joseph southern quebec a formerly glacimarine sedimentary basin that has been glacio isostatically uplifted to form a small lake its study provides a unique opportunity for investigating changes in sedimentary environments from a glacial sea to a postglacial lake multibeam bathymetry allows the observation of two basins separated by a bathymetric ridge and of mass movement deposits in both basins high resolution seismic stratigraphy reveals the presence of seven seismic units these seven units relate to the advance and retreat of the laurentide ice sheet over the region following ice retreat transparent u3 and high amplitude reflection u4 units were deposited during the champlain sea invasion the transparent unit likely represents a rapidly retreating glacier which allowed the deposition of massive silt and clay whereas the high amplitude reflectors which are internally composed of transparent to chaotic lenses are interpreted as the result of a deceleration of ice retreat or a stabilization of the glacier and of glacio isostatic rebound overlying the champlain sea sediments a unit composed of smaller laminations u5 suggests that it was deposited during the marine to lacustrine transition in a paraglacial environment this is supported by its presence in the northern basin where the riviere aux pins mouth is located and its absence in the southern basin where no river is observed the bathymetric ridge between the two basins thus limited sediment transport following the complete retreat of the champlain sea organic rich sediments u7 were deposited in the lake in the northern basin the presence of the riviere aux pins allowed their deposition in the form of rhythmites whereas the absence of rivers in the southern basin resulted in the deposition of an acoustically transparent unit a mass movement u6 identified during the deposition of unit 7 occurred around 1250 ad and is interpreted as earthquake triggered

planetary waves and midlatitude sporadic e layers strong experimental evidence for a close relationship 1 a large amplitude 7 day period westward propagating s 1 planetary wave has been reported from ground radar and satellite wind measurements in the mesosphere lower thermosphere mlt during the second half of august and well into september 1993 following recent suggestions that planetary waves might play a role in the formation of midlatitude sporadic e layers es we have obtained and analyzed for the period from august 1 to september 30 1993 the sporadic e critical frequency foes time series from eight midlatitude ionosonde stations covering a large longitudinal zone from 58 e to 157 w the analysis revealed that all eight station foes data showed a strong 7 day periodicity occurring concurrently with the 7 day planetary wave reported elsewhere using independent methods for the analysis of the foes time series we computed identical estimates for the propagation direction zonal wave number and phase velocity of the 7 day wave which are in agreement with those reported from radar and satellite neutral wind mlt measurements the present findings provide the first direct evidence proving that planetary waves play an important role in the physics of midlatitude sporadic e region layers in addition our results include an important implication that the es parameters measured routinely and rather reliably with a dense global network of digital ionosondes as well as the enormous ionogram databases existing in world data centers may be used as an alternative means of studying large scale neutral atmospheric dynamics in the mlt region

a statistical analysis of sporadic e layer occurrence in the midlatitude china region a statistical analysis of sporadic e layer recorded from september 2011 to september 2015 at four chinese ionospheric sounding stations of mohe 122 37 e 53 50 n beijing 116 25 e 40 25 n wuhan 114 61 e 30 53 n and hainan 109 13 e 19 52 n are presented to investigate the characteristics of sporadic e layer at the middle latitudes over china the occurrence of the sporadic e layer in mid latitude china region shows strong dependence on local time and season consistent with previous studies the occurrence of the mid latitude sporadic e layer is prominent at local daytime in summer season the results also reveal that the post sunset sporadic e layer is statistically pronounced in mid latitude china region possibly related to the nighttime mid latitude e region irregularities the mid latitude sporadic e layer is modulated by atmospheric tidal waves and planetary waves at different latitudes the occurrence of the mid latitude sporadic e layer also tends to increase with the level of geomagnetic activity on basis of both the statistical analysis and case study

in situ elemental and boron isotopic variations of tourmaline from the sanfang granite south china insights into magmatic hydrothermal evolution abstract tourmaline often occurs in boron rich granites and its genesis is still in dispute either formed from residual boron rich silicate melt or from magmatic hydrothermal fluids with or without external fluid involvement here we present a systematic investigation of in situ major trace elemental and boron isotopic variations of tourmaline from the sanfang granite in guangxi province of south china which demonstrate both the magmatic and hydrothermal origin for the formation of the tourmalines the tourmaline occurs mainly in quartz tourmaline nodules and tourmaline pegmatitic segregations within the sanfang granite four types of tourmaline are identified 1 isolated and disseminated tourmaline tur d type distributed in granite 2 euhedral and subhedral tourmaline in quartz tourmaline nodules tur n type 3 the earlier stage tourmaline tur pe type in pegmatitic segregations and 4 the later stage tourmaline tur pl type which replaced the tur pe type tourmaline in pegmatitic segregations all the tourmalines belong to the alkali group representing dravite schorl solid solution series with the former three types being schorl and the tur pl type being dravite petrography chemical discrimination diagrams and al occupations in the y site suggest that the tur d tur n and tur pe type tourmalines are of magmatic origin and the tur pl type tourmalines are of hydrothermal fluid origin elemental and boron isotopic composition variations of tourmalines reflect the compositional and environmental evolution from late boron rich magma to exsolved hydrothermal fluids chemical variations from the tur d to the tur n tourmalines are controlled by magma differentiation the increase of mg mg fe and ca ca na ratios from the tur n to the tur pe tourmalines suggests the contamination of surrounding strata e g the sibao group hydrothermal tourmalines have higher mg mg fe and lower na na ca ratios than the magmatic tourmalines there is clear correlation at least in some trace elements e g sr pb with major elements for all tourmalines indicating the potential crystal chemical effects on their incorporation other trace element incorporation in tourmaline is largely controlled by melt and fluid composition hydrothermal tourmalines have high and stable v co and ni contents indicating relatively constant partition coefficient between hydrothermal tourmalines and the fluid hydrothermal tourmalines exhibit lower total ree contents but more pronounced positive eu anomalies than the magmatic tourmalines the 11b values of all tourmalines from the sanfang granite vary from 14 4 to 9 3 which indicate the boron in the sanfang granite was mainly derived from partial melting of the metasedimentary source rocks boron isotopic variations of tourmaline are controlled by fractionation between melt fluid and rayleigh fractionation

1822 earthquake triggered homogenite in lake le bourget nw alps high resolution textural signatures of an earthquake induced historical homogenite layer are presented as well as its 3d distribution this homogeneous deposit is correlated with the ad 1822 event vii viii msk intensity the main historical earthquake of the french outer alps using 210pb dating and historical chronicles during this earthquake a violent lake water oscillation was reported seiche effect in the present study we discuss the influence of lake water oscillations during earthquake induced subaqueous slide through a pluridisciplinary analysis of subbottom sediments including high resolution seismic sidescan sonar and short gravity coring

reconstructing historical seismicity from lake sediments lake laffrey western alps france sediment archives from a mountain lake are used as indicators of seismotectonic activity in the grenoble area french western alps 45n sedimentological analysis texture and grain size characteristics exhibits several layers resulting from instantaneous deposits in lake laffrey six debris flow events up to 8 cm thick can be attributed to slope failure along the western flank of the basin dating with 210 pb and 137 cs gamma counting techniques and the reconnaissance of historical events provide a constrained age depth model over the last 250 years five of such debris flow deposits could be related to historical earthquakes of msk intensities greater than vi over an area of 60 km one debris flow deposit triggered at the beginning of the last century can be related to an historical landslide possibly triggered by the artificial regulation of the lake level

mf radar observations of meteors and meteor derived winds at syowa 69 s 39 e antarctica a comparison with simultaneous spaced antenna winds 1 the first results of long term meteor observations made with syowa mf radar 69 s 39 e antarctica are presented in winter meteor wind measurements can be conducted throughout the day without being severely affected by group retardation or total reflection while in summer the observations are confined within several hours around 0000 local time lt daily meteor echo rates roughly 300 1000 are clearly anticorrelated with local k indices indicating that the observations mostly represent geomagnetically quiet conditions echoes are distributed from around 80 km to 120 km with the peak altitude at around 100 km the maximum height is set by the relatively slow sampling frequency employed 5 hz and is expected to be extended by using a higher frequency meteor and full correlation analysis fca winds in winter months are compared they agree well at around 90 km while the fca winds tend to underestimate the meteor winds at upper altitudes a notable finding is that the directions of wind velocities can also be different the fca winds show less height variations above about 90 km and it appears as though the fca heights are overestimated a case study of angles of arrival estimated from mf echoes suggests a possibility that meteor echoes contaminate ionospheric echoes down to as low as 80 km however quantitative evaluation of meteor contamination effects if any on fca wind velocities has not been done yet and remains a future topic to be studied other sources which cause the differences should also be sought the remarkably wide height coverage of the present mf radar observations from around 60 to nearly 120 km using both fca and meteor techniques simultaneously will greatly contribute to polar mesosphere and lower thermosphere study

turbidites as records of intense palaeoearthquakes in lake biwa japan abstract some 20 turbidites were collected in the uppermost 3 m of surface sediments in lake biwa southwest japan these turbidites correlate in age to historical earthquakes that caused severe loss of lives and property near lake biwa the age of each turbidite was estimated precisely based on sedimentation rate by weight and the age of tephra markers below the turbidites the magnitudes and epicentres of major historical earthquakes during the last 1300 years are available from historical documents empirical equations relating intensity distance to the epicentre and magnitude enable us to calculate the ground shaking at lake biwa from these historical earthquakes earthquakes having intensity stronger than grade iv l on the japan meteorological agency jma earthquake scale that is 44 gal acceleration at lake biwa all coincide with the turbidite ages this intensity is apparently the lower threshold for turbidity current initiation in lake biwa

meteor observations using the davis mesosphere stratosphere troposphere radar 1 the davis mesosphere stratosphere troposphere mst radar 69 s 78 e was installed in february 2003 although the primary interest is the observation of polar mesosphere summer echoes external transmit and receive antennas were installed to allow all sky interferometric meteor radar observations this paper presents the first results from the meteor observations the annual count rate variation shows good agreement with previous high latitude observations peaking in midsummer and minimizing in early spring the height distribution shows significant annual variation with minimum maximum peak heights and maximum minimum widths observed in early spring midsummer radiant mapping has been used to identify the southern delta aquarid sagittariid and july phoenicid meteor showers and to investigate sources of sporadic meteors winds and temperatures derived from the meteor observations are also presented showing good agreement with independent colocated measurements there is some indication that the winds below the peak height of the meteor height distribution are smeared to lower heights which may be indicative of a previously undocumented bias in meteor wind estimates

documentation of earthquake induced disturbance of lake sediments using subbottom acoustic profiling subbottom acoustic profiling in lakes on the canadian shield and in the canadian cordillera has revealed disruptions in deltaic and lacustrine sediments that can be attributed to large historical earthquakes the timiskaming earthquake of 1935 magnitude 6 25 and the vancouver island earthquake of 1946 magnitude 7 2 triggered extensive slumping and flow of postglacial sediments in lakes located within a few tens of kilometres of the epicentres of these events there is some evidence in one of the surveyed lakes for in situ mobilization of sediment on relatively gentle slopes with minimal horizontal displacement this may be a product of liquefaction induced by coseismic shaking or displacements along faults beneath the basin in another lake widespread coseismic slumping resuspended large amounts of fine sediment which then settled out onto the lake floor to produce a texturally anomalous layer features similar to those produced by the 1935 and 1946 earthquakes can also result from a variety of non

southern argentina agile meteor radar initial assessment of gravity wave momentum fluxes 1 the southern argentina agile meteor radar saamer was installed on tierra del fuego 53 8 s in may 2008 and has been operational since that time this paper describes tests of the saamer ability to measure gravity wave momentum fluxes and applications of this capability during different seasons test results for specified mean tidal and gravity wavefields including tidal amplitudes and gravity wave momentum fluxes varying strongly with altitude and or time suggest that the distribution of meteors throughout the diurnal cycle and averaged over a month allows characterization of both monthly mean profiles and diurnal variations of the gravity wave momentum fluxes applications of the same methods for real data suggest confidence in the monthly mean profiles and the composite day diurnal variations of gravity wave momentum fluxes at altitudes where meteor counts are sufficient to yield good statistical fits to the data monthly mean zonal winds and gravity wave momentum fluxes exhibit anticorrelations consistent with those seen at other midlatitude and high latitude radars during austral spring and summer when no strong local gravity wave sources are apparent when stratospheric variances are significantly enhanced over the drake passage hot spot during austral winter however mlt winds and momentum fluxes over saamer exhibit very different correlations that suggest that mlt dynamics are strongly influenced by strong local gravity wave sources within this hot spot saamer measurements of mean zonal and meridional winds at these times and their differences from measurements at a conjugate site provide further support for the unusual momentum flux measurements

2300 yr history of seismicity from silting events in lake tadoussac charlevoix quebec silt layers in organic rich lake sediments are interpreted to represent the historic earthquakes of 1638 1663 1791 1870 and 1925 of the charlevoix region of eastern canada this interpretation is based on the relative spacing of the layers and the accelerator mass spectrometer sup 14 c dating of a twig in one of the cores the silt layers were presumably caused by landslides on tributary streams and by resuspension of the sediment the cores contain up to 22 layers 1 to 45 mm thick over a depth equivalent to about 2300 yr if there is a correlation between thickness and magnitude there would have been four events of richter magnitude 7 5 or greater in a d 1663 1320 60 and 320 b c the 18 other layers could correspond to earthquakes of magnitude 6 to 7 the recurrence interval from 300 b c to a d 800 is 120 yr followed until a d 1500 by a quiet period when there was a single large event the recurrence interval from a d 1500 to the present is 75 yr

paleoearthquakes on the southern san andreas fault wrightwood california 3000 to 1500 b c a new method for evaluating paleoseismic evidence and earthquake horizons we present evidence of 11 14 earthquakes that occurred between 3000 and 1500 b c on the san andreas fault at the wrightwood paleoseismic site earthquake evidence is presented in a novel form in which we rank high moderate poor or low the quality of all evidence of ground deformation which are called event indicators event indicator quality reflects our confidence that the morphologic and sedimentologic evidence can be attributable to a ground deforming earthquake and that the earthquake horizon is accurately identified by the morphology of the feature in four vertical meters of section exposed in ten trenches we document 316 event indicators attributable to 32 separate stratigraphic horizons each stratigraphic horizon is evaluated based on the sum of rank rs maximum rank rm average rank ra number of observations obs and sum of higher quality event indicators rs 1 of the 32 stratigraphic horizons 14 contain 83 of the event indicators and are qualified based on the number and quality of event indicators the remaining 18 do not have satisfactory evidence for further consideration eleven of the 14 stratigraphic horizons have sufficient number and quality of event indicators to be qualified as probable to very likely earthquakes the remaining three stratigraphic horizons are associated with somewhat ambiguous features and are qualified as possible earthquakes although no single measurement defines an obvious threshold for designation as an earthquake horizon rs rm and rs 1 correlate best with the interpreted earthquake quality earthquake age distributions are determined from radiocarbon ages of peat samples using a bayesian approach to layer dating the average recurrence interval for the 10 consecutive and highest quality earthquakes is 111 93 131 years and individual intervals are 50 of the average with comparison with the previously published 14 15 earthquake record between a d 500 and present we find no evidence to suggest significant variations in the average recurrence rate at wrightwood during the past 5000 years

diurnal and seasonal variability of the meteoric flux at the south pole measured with radars 1 a meteor radar system was installed at the south pole in 2001 to measure the horizontal wind field in the mlt region it uses four 6 element yagi antennas pointing in orthogonal directions for transmission for reception two independent systems are used the same yagi antennas used for transmission cobra data acquisition system and an interferometric array of five crossed dipole antennas medac data acquisition system in this paper we present and discuss vhf radio meteor observations from the south pole preliminary results showing the diurnal and seasonal variability of the meteor flux indicate that most of the activity occurs during the antarctic summer around a very concentrated region of the sky in elevation and azimuth these results agree well with meteor observations performed at arctic latitudes speculations on the radiant distribution and possible meteor sources are presented

u pb ages and lu hf isotopes of detrital zircons from sedimentary units across the mid neoproterozoic unconformity in the western jiangnan orogen of south china and their tectonic implications abstractthe jiangnan orogen located at the southeastern margin of the yangtze block south china records the complete history of assembly and evolution between the yangtze and cathaysia blocks neoproterozoic sedimentary sequences are widespread in the jiangnan orogen with a regional angular unconformity separating the sibao and danzhou groups u pb geochronology and lu hf isotope analyses were carried out on detrital zircons across this unconformity and also the associated granites in the western jiangnan orogen in this study our new results combined with previous data indicate that the sibao and danzhou groups were deposited at 860 832 and 803 764 ma respectively thus this unconformity was constrained to be 832 803 ma detrital zircons from the sibao and danzhou groups have generally similar age populations with three major peaks at 2000 1550 1000 880 and 850 830 760 ma and one minor at 2600 2400 ma the most important generation of juvenile crust appears to have occurred at 2600 2400 ma

sedimentary records of past earthquakes in boraboy lake during the last ca 600 years north anatolian fault turkey abstract multiproxy sedimentological analyses along 4 9 m long sequence of boraboy lake which is located on the central eastern part of the north anatolian fault naf reveal the sedimentary traces of past large earthquakes in the region the lake has a relatively large catchment area 10 km2 compared to its size 0 12 km2 which renders sedimentation sensitive to heavy rain storm events accordingly the background sedimentation which is composed of faintly laminated reddish yellowish brown clayey silt is frequently interrupted by organic rich intercalations probably due to heavy rain storm events transporting terrestrial plant remains from the densely vegetated catchment in addition to frequent organic rich intercalations the background sedimentation is interrupted by four mass wasting deposits mwd of which thickness range is between 15 and 50 cm high resolution itrax xrf data confirms higher homogeneity along the mwds e1 e4 compared to the background sedimentation based on 137cs and 210pbxs dating and radiocarbon chronology three mwds detected in boraboy sequence e2 e3 and e4 temporally correlate with large historical earthquakes along the naf the 1943 tosya ms 7 6 and or 1942 niksar erbaa ms 7 1 the 1776 amasya merzifon and the 1668 north anatolian ms 7 9 earthquakes the youngest mwd in the sequence e1 which is dated to early 2000s does not correlate with any strong earthquake in the region this mwd was probably a single mass wasting event due to routine overloading and oversteepening on the delta front formed by the main inlet of the lake in subaqueous paleoseismology coevality of multi location mass wasting events is used as a criterion to assign a seismic triggering mechanism and to rule out mass wasting events due to routine overloading oversteepening of subaqueous slopes within this context boraboy sequence provides a valuable example to discuss sedimentological imprints of single vs multi source mwds

recognition of trigger mechanisms for soft sediment deformation in the pleistocene lacustrine deposits of the santʻarcangelo basin southern italy seismic shock vs overloading abstract the lacustrine deposits of the san lorenzo cycle belong to the infill succession of the sant arcangelo basin a pliocene to pleistocene satellite basin developed close to the front of the south apennines thrust belt the lower to middle pleistocene lacustrine succession is made up of siltstone and claystone interbedded with sandstone carbonate and volcaniclastic beds arranged in fining upward sequences the upper to middle part about 50 m thick of the succession about 200 m thick has been investigated in detail in the depocentral sector of the lacustrine basin here soft sediment deformation structures occur in fine grained sandstone and claystone alternations and show a wide morphological variability deformed laminations slumps load structures large vertical water escape structures and neptunian dykes their formation occurred during and after sedimentation with different mechanisms of deformation some structures are related to liquefaction and fluidization processes viscous fluid behaviour while others occurred when sediment had already undergone lithification and its behaviour was plastic and or brittle facies analysis and detailed morphologic study of the soft sediment deformation structures indicate that the main trigger agents for deformation were seismic shocks and overloading induced by sudden deposition of coarser sediments on clays due to the arrival of density currents thus the soft sediment deformation structures provide a continuous record of the tectonic and sedimentary processes that acted in the lacustrine basin from sedimentation until diagenesis

seismically triggered organic rich layers in recent sediments from gollukoy lake north anatolian fault turkey abstract multi proxy analyses on the sedimentary sequence of gollukoy lake which is located on the eastern north anatolian fault naf reveals a complete and high resolution paleoseismic record for the last 650 years six sedimentary events are detected in a 3 1 m long piston core they form distinct organic rich intercalations within the background sedimentation which are characterized by strong anomalies on the loss on ignition loi550 and total organic carbon toc profiles as well as by lighter colours on the x ray radiographic images itrax micro xrf core scanner data are also used to contribute to the detection and characterization of the event deposits after the detection of the sedimentary events their temporal correlation with the earthquakes in the historical seismicity catalogue of the naf is tested the youngest event is dated to 1940s by using 210pb and 137cs profiles in sediment which coincides with the 1939 earthquake ms 7 7 on the naf the ages of the older five events are determined based on radiocarbon dating and regional time stratigraphic correlation radiocarbon dating on the bulk sediment samples does not provide reliable results due to hard water effect on the other hand dating on charcoals ephippia of daphnia and phragmite remains significantly improves the results and implies a mean sedimentation rate of 0 28 cm yr based on this preliminary sedimentation rate we show that organic matter content variations through our record correlate with the varve based 18o record of nar lake which is located 350 km southwest of gollukoy lake accordingly high precipitation low evaporation climatic episodes detected in nar lake are represented by higher organic matter content in gollukoy sediments fine tuning the gollukoy loi550 record to the nar 18o record reveals that the ages of the sedimentary events in gollukoy match with well known historical earthquakes that occurred around the lake finally the origin of the organic rich intercalations is discussed based on macroscopic observations and organic geochemistry the events are attributed to reworked organic matter eroded from the lake s littoral zone by seismically induced water oscillations seiche and their subsequent deposition at the middle parts of the lake these seismically induced events are atypical compared to the classic earthquake triggered sedimentary processes in lacustrine environments which are shortly reviewed in order to emphasize the unusual gollukoy lake record

a 2000 yr rupture history for the alpine fault derived from lake ellery south island new zealand determining the earthquake segmentation of plate boundary transform faults remains a scientific challenge because paleoseismic data sets rarely resolve the end points of past ruptures in this study we test whether lacustrine paleoseismology can be used to assess rupture end points and the earthquake segmentation of the alpine fault one of the longest and fastest slipping plate boundary transform faults on earth sediment cores from lake ellery record eight episodes of high intensity shaking modified mercalli intensity mm ix from alpine fault earthquakes as event sequences of a turbidite produced by coseismic subaqueous mass wasting overlain by deposits representing sediment flux from co and postseismic landsliding in the fluvial catchment age depth modeling constrains the timing of shaking events at a decadal resolution facilitating correlation with two previously published lake records to reconstruct the spatial distribution of mm ix shaking along 150 km of the alpine fault when resolved with existing on and near fault paleoseismic records the lake data set demonstrates that independent ruptures of the south westland and central segments occurred in a d 845 775 and a d 739 646 and a d 646 592 and a d 416 370 respectively lakes adjacent to the alpine fault provide paleoseismic records with sufficient spatial and temporal resolution to define along strike differences in the pattern of rupture capable of distinguishing rupture termination at a geometric segment boundary this multilake study suggests that locating the end points of ruptures using lacustrine paleoseismology will be most applicable in midlatitude convergent plate boundary settings where along strike topography and quaternary glaciation have resulted in the widespread distribution of suitable lakes

a new opportunity to detect paleo earthquake events dating back to the past 10 millennia a record from lacustrine sediment bulk density and grain density profiles of the uppermost 90 cm portion of lacustrine sediment from lake suigetsu one of the five major lakes of lake mikatagoko located in central japan indicate the occurrence of at least 10 depositional events characterized by anomalously high density spikes two events are accompanied by turbidites the dates of the sedimentary events estimated here are correlated with the occurrence of destructive earthquakes since 1100 a d close examination of the sedimentological signatures recorded in the lake sediment and historical literature describing destructive earthquake phenomena provides a new opportunity to detect paleo earthquake events in a high seismic area having a long history

paleoseismology in canada a dozen years of progress canadian studies in paleoseismology have led to the publication of over 40 papers in the last 12 years 80 of which have appeared since 1989 considerable progress has been achieved by confirming that the last great earthquake on the cascadia subduction zone happened about 300 years ago and by working toward a chronology of prior earthquakes from their tsunami and turbidite records as yet sparse evidence suggests that the geological effects of large crustal earthquakes are also recorded in southwestern british columbia but there is as yet no chronology in the stable craton of eastern canada studies of silt layers in lakes that are floored by organic sediments have shown considerable potential to provide local earthquake chronologies that can be tested against the more sporadically preserved evidence from liquefaction landslides and other possible indicators of paleoshaking by contrast research using more traditional techniques involving direct examination of faults through geomorphological studies or trenching has been hampered by the difficulty of identifying active faults in the first place on the basis of the past dozen years an accelerating pace of discovery should be expected in the next decade

earthquakes in the eastern great lakes basin from a regional perspective abstract this paper presents a summary of the seismicity and its relation to stress and geologic structures in the eastern great lakes basin eglb and compares it with that of other regions in the central and eastern north america cena the earthquakes scattered throughout the eglb are occurring at a rate somewhat less than that of the appalachians and along the atlantic seaboard paleoseismology studies suggest that the lower seismicity rate may be characteristic of the eglb since the late wisconsin north of the eglb earthquakes have primarily thrust mechanisms while to the south of the eglb most earthquakes are strike slip throughout the region including the eglb the average p axes of the earthquakes are oriented ne sw and are aligned with the direction of the current plate driving stress on a regional basis earthquakes are centered primarily in the precambrian basement beneath the paleozoic cover many of the earthquakes in the eglb have occurred in areas of preexisting faults at least some of which may have been active during past episodes of continental rifting for individual faults that have been studied in some detail however it is not clear whether earthquakes represent reactivations of local preexisting structures or nucleation of new ruptures in or near the old fault zones

a comparison of historical and paleoseismicity in a newly formed fault zone and a mature fault zone north canterbury new zealand the timing of large holocene prehistoric earthquakes is determined by dated surface ruptures and landslides at the edge of the australia pacific plate boundary zone in north canterbury new zealand collectively these data indicate two large m 7 earthquakes during the last circa 2500 years within a newly formed zone of hybrid strike slip and thrust faulting herein described as the porter s pass to amberley fault zone ppafz two earlier events during the holocene are also recognized but the data prior to 2500 years are presumed to be incomplete a return period of 1300 2000 years between large earthquakes in the ppafz is consistent with a late holocene slip rate of 3 4 mm yr if each displacement is in the range 4 8 m historical seismicity in the ppafz is characterized by frequent small and moderate magnitude earthquakes and a seismicity rate that is identical to a region surrounding the structurally mature hope fault of the marlborough fault system farther north this is despite an order of magnitude difference in slip rate between the respective fault zones and considerable differences in the recurrence rate of large earthquakes the magnitude frequency distribution in the hope fault region is in accord with the characteristic earthquake model whereas the rate of large earthquakes in the ppafz is approximated but over predicted by the gutenberg richter model the comparison of these two fault zones demonstrates the importance of the structural maturity of the fault zone in relation to seismicity rates inferred from recent historical and paleoseismic data

quantified sensitivity of small lake sediments to record historic earthquakes implications for paleoseismology seismic hazard assessment is a critical but challenging issue for modern societies a key parameter to be estimated is the recurrence interval of damaging earthquakes this requires the establishment of earthquake records long enough to be relevant i e far longer than historical observations we study how lake sediments can be used for this purpose and explore conditions that enable lake sediments to record earthquakes this was achieved i through the compilation of eight lake sediment sequences from the european alps to reconstruct chronicles of mass movement deposits and ii through the comparison of these chronicles with the well documented earthquake history this allowed 24 occurrences of mass movements to be identified of which 21 were most probably triggered by an earthquake however the number of earthquake induced deposits varies between lakes of a same region suggesting variable thresholds of the lake sequences to record earthquake shaking these thresholds have been quantified by linking the mass movement occurrences in a single lake to both intensity and distance of the triggering earthquakes this method offers a quantitative approach to estimate locations and intensities of past earthquake epicenters finally we explored which lake characteristics could explain the various sensitivities our results suggest that sedimentation rate should be larger than 0 5 mm yr 1 so that a given lake records earthquakes in moderately active seismotectonic regions we also postulate that an increasing sedimentation rate may imply an increasing sensitivity to earthquake shaking hence further paleoseismological studies should control carefully that no significant change in sedimentation rates occurs within a record which could falsify the assessment of earthquake recurrence intervals

a history of pacific northwest earthquakes recorded in holocene sediments from lake washington large earthquakes can trigger slumping of the steep walls of lake basins and landslides in the drainage area resulting in turbidite deposition in the lake and increased detrital flux from inlets holocene sediments in piston cores from lake washington contain a series of terrigenous layers that were episodically deposited in the lake sedimentological geochemical and paleomagnetic analyses on nine piston cores show that the detrital layers are temporally and areally correlatable indicating basinwide disruptions these layers are opaque on x radiographs are coincident with magnetic susceptibility peaks have abundant aluminosilicate minerals are relatively coarse grained and have low organic carbon and biogenic silica contents the thicknesses and geographic distributions of the layers suggest that they are not due to floods or delta destabilization side scan swath imagery and subbottom profiling show that large slumps subaqueous landslides and debris flows are common along the margins of the lake a detailed chronology established from 21 radiocarbon ages on five cores show that a prominent turbidite was deposited about 1000 1100 years ago this turbidite apparently was triggered by a large earthquake that probably occurred on the seattle fault other depositional events in the sediment record at 1500 1700 2400 2500 and 2800 3200 years ago coincide with periods of landsliding that have been previously inferred from the dating of drowned trees in the lake more than 30 depositional events have occurred in the last 12 000 years and 21 disturbances have occurred since the deposition of the mazama ash about 7 600 years ago if all the events are due to earthquakes the puget sound region has been subject to major shaking every 300 to 400 years the strong intensities needed to trigger subaqueous slides may not be generated by just local sources such as the seattle fault but could also be caused by great subduction earthquakes occurring along the coast

late quaternary glacial to postglacial sedimentation in three adjacent fjord lakes of the quebec north shore eastern canadian shield abstract high resolution swath bathymetry imagery allowed mapping in great detail the sublacustrine geomorphology of lakes pentecote walker and pasteur three deep adjacent fjord lakes of the quebec north shore eastern canada these sedimentary basins have been glacio isostatically uplifted to form deep steep sided elongated lakes their key geographical position and limnogeological characteristics typical of fjords suggest exceptional potential for long term high resolution paleoenvironmental reconstitutions acoustic subbottom profiles acquired using a bi frequency chirp echosounder 3 5 12 khz together with cm and m long sediment core data reveal the presence of four acoustic stratigraphic units the acoustic basement unit 1 represents the structural bedrock and or the ice contact sediments of the laurentide ice sheet and reveals v shaped bedrock valleys at the bottom of the lakes occupied by ice loaded sediments in a basin fill geometry unit 2 moraines observed at the bottom of lakes and in their structural valleys indicate a deglaciation punctuated by short term ice margin stabilizations following ice retreat and their isolation the fjord lakes were filled by a thick draping sequence of rhythmically laminated silts and clays unit 3 deposited during glaciomarine and or glaciolacustrine settings these sediments were episodically disturbed by mass movements during deglaciation due to glacial isostatic rebound ams 14c dating reveal that the transition between deglaciation of the lakes pentecote and walker watersheds and the development of para and post glacial conditions occurred around 8000 cal bp the development of the lake head river delta plain during the holocene provided a constant source of fluvial sediment supply to the lakes and the formation of turbidity current bedforms on the sublacustrine delta slopes the upper sediment succession i e 4 6 5 m consists of a continuous para to post glacial sediment drape unit 4 that contains laminated and massive sediment and series of rapidly deposited layers these results allow establishing a conceptual model of how a glaciated coastal fjord evolves during and after deglaciation in a context of rapid glacio isostatically induced forced regression

recurrent liquefaction induced by the 1989 loma prieta earthquake and 1990 and 1991 aftershocks implications for paleoseismicity studies sandblows formed in man made lake deposits near watsonville california resulted from the october 1989 m 7 1 loma prieta earthquake and its april 1990 m 5 5 aftershock and a march 1991 m 4 6 aftershock excavations in the dry bed of soda lake expose the subsurface structure of sandblows induced by the october and april events we also made surface observations three days after the march 1991 event lateral spread fissures developed in the lake sediment during the mainshock and the host deposits were vertically offset 3 to 6 5 cm liquefied sand erupted through the fissures onto the dry lake bed and formed sandblow cone deposits these deposits range from low angle conical structures 30 to 50 cm thick and 2 to 5 m in diameter to elongate deposits up to 35 m long sandblows associated with the april 1990 aftershock commonly reoccupied preexisting fissures but also formed new solitary vents sandblows developed during the march 1991 aftershock erupted only through preexisting vents sandblow vents reactivated in april 1990 contain sediment clasts of sandblow deposits formed in the october 1989 mainshock clasts of host sediment were also present in the sand dikes lamination in the sandblow cones and sand dikes shows that they were not formed in a single episode surface cones and feeder dikes composed of multiple laminated subunits represent the three generations of sandblows the subunits suggest that the cone deposits were formed by pulses of water and sediment expelled from the vent the pulses result from cyclic phases of local excess pore pressure and its release in the liquefied bed at depth the three generations of structures at soda lake formed six months to a year apart have distinct tonal and textural differences that may mimic liquefaction structures formed decades or centuries apart this study provides modern analogs for comparison to and interpretation of prehistoric liquefaction structures that are frequently partly eroded or poorly exposed

neoproterozoic tourmaline bearing peraluminous granitoids in the western jiangnan orogen south china geochemistry petrogenesis and tectonic implications abstract neoproterozoic granitoids are widespread in the jiangnan orogen in south china that was formed by assemblage between the yangtze and cathaysia blocks the peraluminous s type granitoids from the guibei region in the western jiangnan orogen are composed of quartz alkali feldspar and plagioclase with subordinate biotite and muscovite they show large variable feo mgo 1 9 12 8 and k2o na2o cao 2 84 ratios indicating the rocks experienced fractional crystallization their end values 9 31 to 5 45 and two stage nd model ages 1 83 2 34 ga suggest that the guibei granitoids were derived from a mature source that was mainly composed of recycled supracrustal materials the tourmalines occurring as disseminated and nodular grains show high na k 0 56 0 77 apfu low ca 0 01 0 08 apfu and x site vacancy 0 18 0 51 apfu and belong to the alkali group their high fe 1 64 2 28 apfu low mg 0 14 0 80 apfu and mg mg fe 0 016 0 325 suggest that the minerals are dominated by schorl end member in the schorl dravite solid solution series the tourmalines have constant and strong negative 11b values 13 4 to 9 5 and the nodular tourmalines are isotopically lighter 11b 10 0 to 13 4 than the disseminated tourmalines 11b 9 5 to 12 5 the disseminated tourmalines are suggested to have been crystallized in melts at the early magmatic stage whereas the nodular tourmalines formed in fluid rich immiscible melts at the late magmatic stage the boron isotopic variations within or among the tourmaline generations are mainly controlled by rayleigh fractionation in combined with the regional geology the peraluminous granitoids in this study are considered to be partial melts of the supracrustal rocks in the post orogenic setting

increased marine sediment suspension and fluxes following an earthquake earthquakes are commonly cited as one possible triggering mechanism for turbidity flows dense sediment water plumes that can transport large volumes of sediment great distances down slope in both marine and lacustrine settings1 2 3 4 5 6 heezen and ewing1 were the first to make such a suggestion attributing breaks in a sea floor telephone cable in the north atlantic ocean to turbidity flows generated by the 1929 grand banks earthquake anumber of workers have consequently used sedimentary turbidite records to reconstruct the earthquake histories of various regions2 7 8 here we present direct observations of a seismically induced turbidity flow measurements of light scattering and sediment fluxes in the cariaco basin indicate that the earthquake that occurred along the coast of northern venezuela on 9 july 1997 resulted in considerable downslope displacement of sediments probably 105 tonnes into the deep part of the basin in such a seismically active region this mechanism of sediment transport may be responsible for a significant component of the long term sediment accumulation in the basin furthermore this process may result in the sequestration in deep sea sediments of large amounts of carbon initially deposited at shallow depths

erosion under climate and human pressures an alpine lake sediment perspective we review the scientific efforts over the last decades to reconstruct erosion from continuous alpine lake sediment records we focused both on methodological issues showing the growing importance of non destructive high resolution approaches xrf core scanner as well as progresses in the understanding of processes leading to the creation of an erosion signal in lakes we distinguish continuous records from event records both provide complementary information but need to be studied with different approaches continuous regionally relevant records proved to be particularly pertinent to document regional erosion patterns throughout the holocene in particular applying the source to sink approach event based approaches demonstrated and took advantage of the strong non linearity of sediment transport in high altitude catchment areas this led to flood frequency and intensity reconstructions highlighting the influence of climate change upon flood dynamics in the mountain the combination of different record types both in terms of location high vs low elevation sedimentology high vs low terrigenous contribution and significance local vs regional is one of the main outputs of this paper it allows the establishment of comprehensive histories of nw french alps erosion but also and consequently soil dynamics and hydrological patterns throughout the holocene we also discuss the influence of glacier dynamics one of the major agents of erosion in the alps a major feature is the growing human influence upon erosion at a local scale since at least the middle of the bronze age 3500 cal bp however and according to the regional record from lake bourget only few periods of rising erosion at local scales generated a regional record that can be discriminated from wetter climatic periods among them the period between 200 bce and 400 ad appeared to be marked by a generalised rise in human triggered erosion at local scales in the northern french alps this review highlights the importance of modern high resolution and interdisciplinary studies of lake sediments in order to better understand the complex relationships between humans climate and the earth system in general we strongly argue that regional integration of data is now required to move a step further such an integration is easier with cost and time effective methods as well as after a better definition of approaches and their limits this should lead to a stronger collaboration between paleo data producers and modellers in the near future

flood stratigraphies in lake sediments a review abstract records of the frequency and magnitude of floods are needed on centennial or millennial timescales to place increases in their occurrence and intensity into a longer term context than is available from gauged river flow and historical records recent research has highlighted the potential for lake sediment sequences to act as a relatively untapped archive of high magnitude floods over these longer timescales abyssal lake sediments can record past floods in the form of coarser grained laminations that reflect the capacity for river flows with greater hydrodynamic energy to transport larger particles into the lake this paper presents a framework for investigating flood stratigraphies in lakes by reviewing the conditioning mechanisms in the lake and catchment outlining the key analytical techniques used to recover flood records and highlighting the importance of appropriate field site and methodology selection the processes of sediment movement from watershed to lake bed are complex meaning relationships between measureable sedimentary characteristics and associated river discharge are not always clear stratigraphical palaeoflood records are all affected to some degree by catchment conditioning fluvial connectivity sequencing of high flows delta dynamics as well as within lake processes including river plume dispersal sediment focussing re suspension and trapping efficiency with regard to analytical techniques the potential for direct e g laser granulometry and indirect e g geochemical elemental ratios measurements of particle size to reflect variations in river discharge is confirmed we recommend care when interpreting fine resolution geochemical data acquired via micro scale x ray fluorescence xrf core scanning due to variable down core water and organic matter content altering x ray attenuation we also recommend accounting for changes in sediment supply through time as new or differing sources of sediment release may affect the hydrodynamic relationship between particle size and or geochemistry with stream power where these processes are considered and suitable dating control is obtained discrete historical floods can be identified and characterised using palaeolimnological evidence we outline a protocol for selecting suitable lakes and coring sites that integrates environmental setting sediment transfer processes and depositional mechanisms to act as a rapid reference for future research into lacustrine palaeoflood records we also present an interpretational protocol illustrating the analytical techniques available to palaeoflood researchers to demonstrate their utility we review five case studies of palaeoflood reconstructions from lakes in geographically varied regions these show how lakes of different sizes and geomorphological contexts can produce comprehensive palaeoflood records these were achieved by consistently applying site validated direct and proxy grain size measurements well established chronologies validation of the proxy process interpretation and calibration of the palaeoflood record against instrumental or historical records