a refined age calibrated paleosecular variation and relative paleointensity stack for the nw barents sea implication for geomagnetic field behavior during the holocene abstract reconstruction of paleomagnetic secular variation psv of the geomagnetic field is fundamental both to assess geodynamo models and to obtain age constraints for rocks sediments and archaeological material we present refined age calibrated holocene psv and relative paleointensity rpi stack curves derived from arctic marine sediments northwestern barents sea the holocene sections of four sedimentary cores were correlated on the basis of paleomagnetic trends and age models and stacked the resultant composite psv and rpi holocene records nbs stack and the reconstructed holocene virtual geomagnetic pole vgp path were evaluated in comparison with the most recent paleomagnetic stack curves and geomagnetic field models the data indicate that during the holocene time the vgps moved within the superficial projection of the inner core tangent cylinder with the exception of short time intervals around 5600 and 3200 cal yr bp when vgps extended to lower latitudes these deviations might reflect regional geomagnetic features such as persistent geomagnetic flux lobes at core mantle boundary our data confirm that the large vgp shift observed around 5600 cal yr bp is the result of an increased radial magnetic field at the core mantle boundary over north america whilst the vgp shift around 3200 cal yr bp represents a major swing to middle latitudes toward the middle east and might be associated to a regional high paleointensity peak known as levantine iron age anomaly liaa

marine isotope stage mis 8 millennial variability stratigraphically identical to mis 3 the marine isotope stage mis 3 stratigraphy is highly robust and was reproduced during another period mis 8 6 global ice volume was similar during mis 8 6 to mis 3 60 to 90 m sea level equivalent but the milankovitch insolation forcing was different implying that earth s predisposition to millennial internal variability is controlled by the configuration of the major ice sheets the involvement of additional factors cannot be ruled out but by identifying several such periods using new deep ice cores from dome concordia and dome fuji antarctica as well as the marine record we may isolate the factors predisposing earth to these highly significant modes of climate variability

a new rock magnetic approach to selecting sediments for geomagnetic paleointensity studies application to paleointensity for the last 4000 years the hypothesis that the ratio of detrital remanent magnetization to anhysteretic remanent magnetization drm arm for sediment samples is a measure of relative geomagnetic paleointensity is critically evaluated by two distinct approaches one approach is a detailed rock magnetic examination of the implicit assumptions of the drm arm method and the construction of a selection process by which to identify sediments that conform to requirements satisfying these assumptions sediments are uniform with respect to drm arm ratio if they contain magnetite in the 1 15 ym particle size range as the predominant magnetic mineral and have variations in magnetite content of less than 20 30 times the minimum concentration the drm arm ratios of these sediments should provide estimates of relative geomagnetic paleointensity relative particle size variations in magnetite are detected with a plot of anhysteretic susceptibility xarm versus low field susceptibility x and the size range 1 15 m is approximately identified by high field hysteresis parameters a rock magnetic evaluation of leboeuf lake sediments with these techniques indicates that these sediments are suitable for a relative plaeointensity study the second approach to evaluating the drm arm ratio as a measure of relative paleointensity is direct comparison with absolute paleointensity data a comparison between the leboeuf lake estimates and thellier thellier results from the western united states supports the conclusion that suitable sediments can record geomagnetic paleointensity fluctuations

fennostack and fennorpis varve dated holocene palaeomagnetic secular variation and relative palaeointensity stacks for fennoscandia a holocene palaeomagnetic secular variation master curve fennostack and a relative palaeointensity curve fennorpis for fennoscandia are presented these curves were produced by stacking palaeomagnetic data obtained from six annually laminated varved lake sediment sequences and one non laminated sediment sequence the six independent varve chronologies were combined to form a timescale which extends between the present year and 10 200 cal yr bp smoothed inclination and declination curves show trends that are similar to a palaeomagnetic secular variation curve for the united kingdom except that the ages of most of the statistically significant features are a few hundred years younger in the fennoscandian data set these differences are most likely due to excessively old ages of the united kingdom features produced by the radiocarbon dating of bulk sediments the standardized relative palaeointensity stack shows that the intensity of the geomagnetic field in fennoscandia was highest at 2300 cal yr bp and lowest at 7000 cal yr bp three palaeointensity peaks pips and three palaeointensity lows pils are identified in fennorpis and indicate that the intensity of geomagnetic field varied significantly on millennial scales in this region during the holocene but there is much scatter in the reconstruction prior to 8000 cal yr bp higher frequency palaeointensity features present in individual records are not significant in the stacked data set which implies that these are a result of local environmental bias significant discrepancies exist between the data and the output of the cals7k 2 geomagnetic field model for the last 7000 yr in particular the largest declination swing observed in the data at 2670 cal yr bp feature f is not produced by the model which is most likely due to the influence of an inaccurately dated icelandic secular variation curve on the model result short term trends in standardized relative palaeointensity do differ from the model output but it is difficult to make a comparison because of the relative nature of the sediment record better absolute palaeointensity data are needed to reduce uncertainties in reconstructions of past geomagnetic field strength

sedimentary records of relative paleointensity of the geomagnetic field theory and practice sediments have proved irresistible targets for attempts at determining the relative variations in the earth s magnetic field because of the possibility of long and continuous sequences that are well dated and have a reasonable global distribution the assumption underlying paleointensity studies using sedimentary sequences is that sediments retain a record reflecting the strength of the magnetic field when they were deposited early theoretical work suggested that because the time required for an assemblage of magnetic particles in water to come into equilibrium with the ambient magnetic field was quite short no dependence on magnetic field was expected nonetheless a number of experiments showed that sedimentary magnetizations varied in accordance with the field albeit not always in a simple linear fashion experiments in which the sediments were stirred in the presence of a field to simulate bioturbation showed a reasonably linear relationship with the applied field and these results spurred the hope that variations in the earth s magnetic field might indeed be recoverable from appropriate sedimentary sequences examination of existing paleointensity data sets allows a few general conclusions to be drawn it appears that sedimentary sequences can and do provide a great deal of information about the variations in relative paleointensity of the earth s magnetic field the dynamic range of sedimentary data sets is comparable to those acquired from thermal remanences moreover when compared directly with such independent measures of magnetic field variations as beryllium isotopic ratios and thermally blocked remanences there is considerable agreement among the various records when viewed over timescales of hundreds to thousands of years relative paleointensity data sets from more than a few thousand kilometers apart bear little resemblance to one another suggesting that they are dominated by nondipole field behavior when viewed over timescales of a few tens of thousands to hundreds of thousands of years however the records show coherence over large distances at least thousands of kilometers and may reflect changes in the dipole field on the basis of a sequence spanning the brunhes and matuyama chrons the magnetic field has oscillated with a period of about 40 ka for the last few hundred thousand years but these oscillations are not clear in the record prior to about 300 ka thus they are probably not an inherent feature in the geomagnetic field and the correspondence of the period of oscillation to that of obliquity is probably coincidence

palaeogeography of atlantic canada 13 0 kyr abstract we combine isobase maps with a digital terrain model of atlantic canada to map coastlines from 13 14c kyr bp to the present at 13 14c kyr bp there are ridges of high relative sea level rsl values over newfoundland and the maritime provinces and a re entrant of low values in the gulf of st lawrence this pattern persists well into the holocene and reflects crustal response to the slow wasting of ice caps that persisted in newfoundland and the maritime provinces for up to five millennia after the removal of ice from the gulf of st lawrence by a migrating calving embayment the palaeogeographic reconstructions reveal an archipelago on the outer shelf from grand bank to the continent that persisted from 13 14c kyr bp until ca 8 14c kyr bp much of the magdalen shelf was exposed but the magdalen islands were never connected to the mainland prince edward island was initially separated from the mainland became connected after 11 14c kyr bp and was separated again just before 6 14c kyr bp when northumberland strait formed the reconstructions are highly sensitive to relatively small changes in isobase values especially on the shallow banks on the continental shelf

late quaternary morpho sedimentology and submarine mass movements of the betsiamites area lower st lawrence estuary quebec canada abstract a complex submarine geomorphology was revealed from multibeam bathymetry and seismic reflection surveys conducted between 2001 and 2007 in the lower st lawrence estuary offshore betsiamites river quebec canada in this paper we describe the submarine morpho sedimentology of an area of 500 km 2 with focus on the consequences of four mass movement events the general morpho sedimentology of the area and submarine features resulting from mass movement processes channel erosion and gas seepage are described a spatio temporal sequence for the occurrence of the mass movements and a chronology for the failures are established we propose dates for four of the observed mass movement deposits a buried paraglacial debris flow deposit is dated as older than 9280 cal bp whereas a major landslide scar characterized by two topographic depressions on the shelf and a sediment lobe in the laurentian channel were dated around 7250 cal bp morphological observations and sediment core analyses allow us to identify a least two different recent i e less than 500 yr old debris flow accumulations associated with two recent earthquakes 1 the ad 1663 m 7 and 2 ad 1860 m 6 or ad 1870 m 6 5 earthquakes in addition to a complex geomorphology influenced by mass movements we have identified several regions on the shelf and on the laurentian channel with evidence of pockmarks which could potentially influence submarine slope stability in the estuary

paleosecular variations of the geomagnetic field during the holocene from eastern asia abstract high resolution paleomagnetic secular variation psv records bear great information of dynamics processes of the earth s geomagnetic field and can be further used for inter profile correlation and for dating sediments however effects of changes in the depositional environment on psv records have not been fully determined this study constructed holocene psv records for the gravity piston core zsqd34 obtained from the northern south china sea rock magnetic and transmission electron microscope tem results indicate that single sd and psd domain magnetites are the main carrier of the natural remanent magnetization comparable to the records derived from the freshwater lakes and the modeling results we observed that direction curves from these two environments of contrasting salinity content are rather consistent the direction curves are independent of the constructed salinity however the gradual increasing trend of relative intensity since about 5 kyr might be related to the decreasing sea surface salinity furthermore on the centennial and millennial time scale the relative intensity and salinity show some positive relation suggesting a potential contribution of salinity to the paleomagnetic relative intensity recording processes

the subglacial origin of the lake agassiz ojibway final outburst flood arc shaped scours sandwaves and channels on the hudson bay seafloor suggest that the catastrophic drainage of lake agassiz ojibway occurred as a subglacial flood beneath the laurentide ice sheet which covered northern north america

cat scan analysis of sedimentary sequences an ultrahigh resolution paleoclimatic tool paleoclimate research is essential to determine the natural variability of climate and to place the current climate change into its natural context the current need is to generate the highest temporal resolution paleoclimatic reconstructions possible in order to assess the natural variability of the climate system but also to test the ability of numerical models to simulate conditions different from the ones observed with the relatively short instrumental records in this paper we show that cat scan analysis of sedimentary sequences with its 1 mm downcore resolution can be used to identify millennial to seasonal cycles in sedimentary sequences in examples from the st lawrence estuary eastern canada spectral analysis of the cat scan data from holocene postglacial sediments revealed millennial to centennial scale oscillations possibly associated with either solar variability changes in relative sea level or tidal amplitude similarly spectral analysis of holocene and sangamonian glaciomarine sequences revealed decadal to annual scale oscillations with periods close to the one previously associated with the north atlantic oscillation nao whereas spectral analysis of the cat scan data from the sangamonian rhythmites possibly revealed seasonal cycles

high resolution paleomagnetic and sedimentological investigations on the tibetan plateau for the past 16 ka cal b p the tangra yumco record the spatial distribution of paleomagnetic secular variation psv records on the tibetan plateau and adjacent areas covering the holocene and late glacial is sparse in order to reconstruct psv in this area a piston core covering the past 17 5 ka cal b p retrieved from lake tangra yumco southern central tibetan plateau was analyzed in the laminated sediments several event layers are intercalated those were identified by sedimentological analysis and excluded for age depth modeling and interpretation paleomagnetic measurements on u channels reveal two contrasting core sections the lower section dated to 17 5 15 9 ka cal b p is very coarse grained up to 220 m and characterized by low intensities 0 8 ma m 1 and high maximum angular deviation values mean 25 making it unsuitable for psv reconstruction in contrast the upper unit dated to 15 9 ka cal b p yields ideal properties with a well defined magnetization carried by low coercivity minerals in the pseudo single domain state making those younger sediments a proper record for psv studies the robustness of the psv reconstruction for the past 3000 years is highlighted by a comparable inclination and declination pattern of three short sediment cores 2 m from tangra yumco on a regional scale the obtained inclination signal for the past 15 9 ka cal b p is in good agreement with the lake baikal record 3000 km to the north psv stack for east asia as well as with predictions of geomagnetic field models this study is a step forward in constructing a psv reference curve for central asia keywords paleomagnetic secular variations psv magnetostratigraphy tibetan plateau lake sediments tangra yumco inclination

post depositional remanent magnetization lock in depth in precisely dated varved sediments assessed by archaeomagnetic field models accurate and precise chronologies are needed to evaluate the existence and effect of a post depositional remanent magnetization lock in process on sedimentary palaeomagnetic records here we present lock in modelling results of two palaeomagnetic records from varved lake sediments lakes kalksjon and gyltigesjon in sweden by using model predictions based on archaeomagnetic data we used the c 14 wiggle match dating technique to improve the precision of the kalksjon varve chronology in the period between 3000 and 2000 cal bp which is characterized by pronounced palaeomagnetic secular variation this method allowed us to infer an age model with uncertainties of 20 years 95 4 probability range furthermore we compared the palaeomagnetic record of kalksjon to gyltigesjon which has a corresponding 14c wiggle matched chronology the ages of palaeomagnetic features derived from the wiggle matched varve chronologies are older than those predicted by the archaeomagnetic models lock in modelling was performed with different filter functions to explain the temporal offset and the amplitude of the lake sediment palaeomagnetic data the analyses suggest that a linear lock in function with lock in depths the depth below which no more natural magnetic remanence is acquired that range between 30 and 80 cm in kalksjon and 50 and 160 cm in gyltigesjon are most appropriate to explain the data these relatively deep lock in depths in sediments without a bioturbated mixed zone can be attributed to the relatively high organic contents and low density of the lake sediments which contribute to a thick unconsolidated upper zone of the sediment sequence in which re alignment of magnetic particles can take place c 2014 elsevier b v all rights reserved

regionally consistent western north america paleomagnetic directions from 15 to 35 ka assessing chronology and uncertainty with paleosecular variation psv stratigraphy abstract new paleomagnetic secular variation psv data from fish lake utah usa along with previously published regional records allow us to build an independently dated western north america psv stack wnam17 from about 35 to 15 ka that quantifies dating and paleomagnetic uncertainties in february 2014 we recovered a composite 11 m long sediment record from fish lake utah that retrieved glacially influenced and post glacial sediments computed tomography ct scans and magnetic susceptibility were used to build a precise depth scale while radiocarbon dating of terrestrial macrofossils and tephrostratigraphy provide tight age control glacially influenced sediments have well defined characteristic remanent magnetizations with all maximum angular deviation values

time variations in geomagnetic intensity 1 after many years spent by paleomagnetists studying the directional behavior of the earth s magnetic field at all possible timescales detailed measurements of field intensity are now needed to document the variations of the entire vector and to analyze the time evolution of the field components a significant step has been achieved by combining intensity records derived from archeological materials and from lava flows in order to extract the global field changes over the past 12 kyr a second significant step was due to the emergence of coherent records of relative paleointensity using the remanent magnetization of sediments to retrace the evolution of the dipole field a third step was the juxtaposition of these signals with those derived from cosmogenic isotopes contemporaneous with the acquisition of records new techniques have been developed to constrain the geomagnetic origin of the signals much activity has also been devoted to improving the quality of determinations of absolute paleointensity from volcanic rocks with new materials proper selection of samples and investigations of complex changes in magnetization during laboratory experiments altogether these developments brought us from a situation where the field changes were restricted to the past 40 kyr to the emergence of a coherent picture of the changes in the geomagnetic dipole moment for at least the past 1 myr on longer timescales the field variability and its average behavior is relatively well documented for the past 400 myr section 3 gives a summary of most methods and techniques that are presently used to track the field intensity changes in the past in each case current limits and potential promises are discussed the section 4 describes the field variations measured so far over various timescales covered by the archeomagnetic and the paleomagnetic records preference has always been given to composite records and databases in order to extract and discuss major and global geomagnetic features special attention has been devoted to discussing the degree of confidence to be put in the data by considering the integration of multiple data sets involving different techniques and or materials

holocene paleomagnetic secular variation psv near 80 n northwest spitsbergen svalbard implications for evaluating high arctic sediment chronologies abstract we present a paleomagnetic study of two holocene lake sediment sequences from northwest spitsbergen on svalbard norway core hap 212 from lake hajeren preserves a rare combination of a well defined characteristic remanent magnetization chrm and robust age control defined by 21 terrestrial macrofossil derived radiocarbon dates providing a unique opportunity to assess the stratigraphic potential of high arctic holocene paleomagnetic secular variation psv close to 80 n core amp 112 from hakluytvatnet which is also well dated is a poor magnetic recorder and cannot be used for geomagnetic reconstruction comparison of the hap 212 psv record with poorly dated regional records show similar directional features suggesting that psv can be used for chronological synchronization comparison of the hap 212 psv with well dated records 1800 km to the southwest and southeast show that these records are in phase at millennial timescales within dating and magnetic uncertainties indicating that a consistent geomagnetic signal is recorded at these temporal and spatial scales these findings support the notion that psv when optimally recorded can be used to import chronologies from lower latitudes to the high arctic where low organic content hard water effects lack of datable material and other difficulties often preclude more conventional radiocarbon dating

holocene secular variation in western north america paleomagnetic record from fish lake harney county oregon an 8 9 m composite section of lake sediment from fish lake steens mountain southeastern oregon has provided a high resolution record of holocene geomagnetic secular variation in western north america the section is composed of overlapping core segments with stratigraphic control based on six tephra layers and other thin distinct bands and with age control from 37 radiocarbon dates the 455 paleomagnetic samples possess a strong and stable magnetic remanence which is carried by pseudo single domain magnetite paleomagnetic records for individual core segments show low scatter and high serial correlation and where the segments overlap there is excellent agreement between records the azimuthal orientation of the composite section was recovered from the known direction of the geomagnetic field at the time of the climactic eruption of mount mazama tephra which is present in fish lake both internal and external evidence including the correspondence with an archaeomagnetic record from the southwestern united states support the conclusion that the fish lake record represents the history of geomagnetic field behavior during at least the last 10 000 years b p analysis of that record reveals that the average geomagnetic direction can not be distinguished from that of a geocentric axial dipole field and that the overall circularity of the field was clockwise but the detailed behavior was quite complex angular standard deviations of both field directions and virtual geomagnetic poles differ significantly from the values predicted from theoretical models of secular variation but are consistent with those of other holocene records when the record from fish lake is compared to the proposed type curve for east central north america there is excellent agreement for the past 6000 years provided the curves are offset by about 400 years this offset corresponds to a rate of westward drift of about 0 062 yr beyond about 6000 radiocarbon years ago good agreement between the two curves occurs when there is no offset suggesting that the field was standing rather than drifting during this time

a physically based model for the topographic control on shallow landsliding a model for the topographic influence on shallow landslide initiation is developed by coupling digital terrain data with near surface through flow and slope stability models the hydrologic model topog o loughlin 1986 predicts the degree of soil saturation in response to a steady state rainfall for topographic elements defined by the intersection of contours and flow tube boundaries the slope stability component uses this relative soil saturation to analyze the stability of each topographic element for the case of cohesionless soils of spatially constant thickness and saturated conductivity the steady state rainfall predicted to cause instability in each topographic element provides a measure of the relative potential for shallow landsliding the spatial distribution of critical rainfall values is compared with landslide locations mapped from aerial photographs and in the field for three study basins where high resolution digital elevation data are available tennessee valley in marin county california mettman ridge in the oregon coast range and split creek on the olympic peninsula washington model predictions in each of these areas are consistent with spatial patterns of observed landslide scars although hydrologic complexities not accounted for in the model e g spatial variability of soil properties and bedrock flow control specific sites and timing of debris flow initiation within areas of similar topographic control

late quaternary paleomagnetic field secular variation from two minnesota lakes detailed paleomagnetic records from the wet sediments of two minnesota lakes are the basis for estimating the local secular variation of the earth s magnetic field during late quaternary time results from lake st croix cover the interval 0 9500 years b p and results from kylen lake cover the interval 4000 14 000 years b p paleomagnetic data were recovered from two replicate cores in each lake by sampling the sediments at 3 to 10 cm intervals analysis of the potential errors in the results indicates that all cores were correctly oriented in the vertical plane but that some azimuthal offsets of individual core segments did occur various methods for correcting the occasional azimuthal offsets are described the final paleomagnetic data sets from each lake show a high degree of internal consistency these results also show close correspondence 1 between the two lakes 2 with the known historic magnetic field variation and 3 with paleomagnetic results from dated archeological material and lava flows from the western united states rock magnetic analysis of the lake sediments indicates that the natural remanent magnetization is the result of a physical remanence acquisition process detrital remanent magnetization active at or near the sediment water interface there is no evidence for a systematic inclination error in the results statistical analysis of vector time series determined from the paleomagnetic data indicates that both the field vector and virtual geomagnetic pole vgp distributions are non fisherian and essentially axial dipolar when averaged over 10 000 years spectral analysis of the scalar inclination and declination suggests that the field behavior is separable into a dominant low frequency dipolelike waveform period of 9500 years and a higher frequency band irregular waveform fundamental period of 2400 years with multiples at 1200 800 and 600 years that may represent the nondipole field this irregular waveform is interpreted as resulting from zonal drift of the nondipole field past minnesota on the basis of waveform morphology and vgp circularity zonal drift of the nondipole field plus a low frequency dipole variation can account for almost all of the observed paleomagnetic field variation

coring induced sediment fabrics at iodp expedition 347 sites m0061 and m0062 identified by anisotropy of magnetic susceptibility ams criteria for accepting palaeomagnetic data anisotropy of magnetic susceptibility data obtained from discrete subsamples recovered from two integrated ocean drilling program sites expedition 347 sites m0061 and m0062 in the baltic sea by a

modelling the probability of occurrence of shallow landslides and channelized debris flows using geotop fs this paper describes a coupled distributed hydrological geotechnical model geotop fs which simulates the probability of occurrence of shallow landslides and debris flows we use a hydrological distributed model geotop which models latent and sensible heat fluxes and surface runoff and computes soil moisture in 3 d by solving richards equation numerically together with an infinite slope geotechnical model geotop fs the combined model allows both the hydraulic and geotechnical properties of soil to be considered and realistically modelled in particular the model has been conceived to make direct use of field surveys geotechnical characteristics and soil moisture measurements in the model the depth of available sediments is also used to characterize the hydraulic properties of the area examined to account for the uncertainty related to the natural variability in the factors influencing the stability of natural slopes the safety factor is computed with a probabilistic approach in order to determine the likelihood of slope failures soil parameters are assigned distributions instead of single deterministic values the analysis presented was carried out for an alpine watershed located in the friuli region italy for which some geological and geotechnical data were available in the past this watershed experienced landslides and debris flows during intense storms following long and moderate intensity rainfall events the distributed coupled geotop fs model was calibrated by reproducing some of these events and validated in order to map future failure probabilities

secular variation of the geomagnetic dipole during the past 2000 years we have constructed a very simple model of a time varying geocentric dipole based on the archeomagnetic records obtained at four widely separated sites on the globe for the past 2 ka the predictions of the model in terms of directional variations have been tested against actual archeomagnetic data from 12 sites distributed over the globe they were also compared with the hongre et al 1998 time varying spherical harmonic model and with the cals7k 2 model by korte et al 2005 we find that the misfits between the predictions of our simple dipole model and the data are equivalent to those of the spherical harmonic models for the european sites and not strikingly larger for the rest of the world many discrepancies can be accounted for by uncertainties inherent to the archeomagnetic records which along with the small number and poor geographical distribution of sites leads us to conclude that the present state of the database does not allow the extraction of secular variations described by terms going beyond degree 2 it appears also that dipole tilt could be responsible for the main part of the secular variation associated with time constants exceeding 102 years in a second step we used the paleointensity records contained in the same database to construct the curve depicting the variations of the true dipole moment the present decrease of the dipole did not begin prior to 1000 years ago and the dipole was actually increasing from 0 until a d 500 the dipole moment of cals7k is lower than the present estimate probably due to large repartition of energy to higher harmonics to minimize the misfit between the inversion and the data the tilt and strength of the dipole can predict the dipole field at any site and were used to derive the contribution of the nondipole field to values of paleointensity at paris during the past 2 ka the results show that the archeomagnetic jerks are associated with various configurations depending on the phase relationship between the nondipolar and dipolar parts of the field

geomagnetic palaeosecular variation 0 13 000 yr bp as recorded in sediments from three maar lakes from the west eifel germany summary geomagnetic palaeosecular variation psv profiles have been obtained from 12 cores raised from three maar lakes in the west eifel germany age control is provided by varve chronology analysis of mean inclinations suggests that a post depositional remanent magnetization pdrm was acquired in all three lakes a lock in time of 150 yr corresponding to an average lock in depth of 24 cm has been determined from a comparison with archaeomagnetic sv data stacked psv results demonstrate directional geomagnetic field behaviour through the late and post glacial in central europe and show good agreement with the holocene british master curve turner thompson 1982 psv results suggest that westward drift of the non dipole field was not persistent over the last 13 000 yr spectral analyses yield declination variations with durations of about 1800 yr in the younger holocene 0 5000 yr bp and 4300 yr between 5000 and 13 000 yr bp the inclination exhibits swings of 1000 yr duration in the younger holocene and about 2000 yr in the older part moreover inclination spectra suggest the presence of one inclination variation with a very long duration approaching the length of the time span investigated 8600 yr

a paleomagnetic approach toward refining holocene radiocarbon based chronologies paleoceanographic records from the north iceland md99 2269 and east greenland md99 2322 margins 1 we report the intercalibration of paleomagnetic secular variation psv and radiocarbon dates of two expanded postglacial sediment cores from geographically proximal but oceanographically and sedimentologically contrasting settings the objective is to improve relative correlation and chronology over what can be achieved with either method alone core md99 2269 was taken from the hunafloaall trough on the north iceland shelf core md99 2322 was collected from the kangerlussuaq trough on the east greenland margin both cores are well dated with 27 and 20 accelerator mass spectrometry 14c dates for cores 2269 and 2322 respectively paleomagnetic measurements made on u channel samples document a strong stable single component magnetization the temporal similarities of paleomagnetic inclination and declination records are shown using each core s independent calibrated radiocarbon age model comparison of the psv records reveals that the relative correlation between the two cores could be further improved starting in the depth domain tie points initially based on calibrated 14c dates are either adjusted or added to maximize psv correlations radiocarbon dates from both cores are then combined on a common depth scale resulting from the psv correlation support for the correlation comes from the consistent interweaving of dates correct alignment of the saksunarvatn tephra and the improved correlation of paleoceanographic proxy data percent carbonate these results demonstrate that psv correlation used in conjunction with 14c dates can improve relative correlation and also regional chronologies by allowing dates from various stratigraphic sequences to be combined into a single higher dating density age to depth model

palaeomagnetic intensity data an achilles heel of solar activity reconstructions reconstructions of solar activity prior to ad1600 rely on estimates of the past production rates of cosmogenic radionuclides in the earth s atmosphere these rates are modulated by the strength of the solar magnetic field and the intensity of the earth s geomagnetic dipole one of the largest uncertainties associated with these reconstructions originates from palaeointensity data and to show how errors in palaeomagnetic data influence reconstructions of solar activity we present different radiocarbon based reconstructions of the solar magnetic modulation parameter during the holocene we considered geomagnetic field changes according to i a global archaeomagnetic compilation ii a geomagnetic field model covering the last 7000 years and iii a regional sediment relative palaeointensity record comparison between alternative solar modulation reconstructions shows that the uncertainties in palaeomagnetic data prevent us from making robust conclusions about solar variability at timescales longer than a few hundred years our analyses indicate that the geomagnetic dipole field dominates radiocarbon production at frequencies lower than 1 500 yr 1 although a combination of solar and magnetic modulation could apply to all time scales long term trends depend on which palaeomagnetic data set is used for correction and there are additional unexplained differences between 10be and 14c records that question results about long term changes in solar activity the higher resolution geomagnetic field records which are usually very much smoothed in stacked records also indicate that part of the shorter term changes 500 yr in the radiocarbon production rate could be attributed to the geomagnetic dipole field to test this theory and improve our knowledge of past solar activity a higher resolution palaeomagnetic reconstruction of geomagnetic dipole moment is required less

a holocene paleosecular variation record from the northwestern barents sea continental margin a high resolution paleomagnetic and rock magnetic study has been carried out on sediment cores collected in glaciomarine silty clay sequences from the continental shelf and slope of the southern storfjorden trough mouth fan on the northwestern barents sea continental margin the storfjorden sedimentary system was investigated during the svais and eglacom cruises when 10 gravity cores with a variable length from 1 03 m to 6 41 m were retrieved accelerator mass spectrometry ams 14c analyses on 24 samples indicate that the cores span a time interval that includes the holocene the last deglaciation phase and in some cores the last glacial maximum the sediments carry a well defined characteristic remanent magnetization and have a valuable potential to reconstruct the paleosecular variation psv of the geomagnetic field including relative paleointensity rpi variations the paleomagnetic data allow reconstruction of past dynamics and amplitude of the geomagnetic field variations at high northern latitudes 75 76 n at the same time the rock magnetic and paleomagnetic data allow a high resolution correlation of the sedimentary sequences and a refinement of their preliminary age models the holocene psv and rpi records appear particularly sound since they are consistent between cores and they can be correlated to the closest regional stacking curves uk psv fennostack and fennorpis and global geomagnetic model for the last 7 ka cals7k 2 the computed amplitude of secular variation is lower than that outlined by some geomagnetic field models suggesting that it has been almost independent from latitude during the holocene

late glacial stratigraphy and history of the gulf of st lawrence reply the three dimensional configuration of the quaternary sediments in the gulf of st lawrence is described based on analysis of 8000 km of high resolution seismic reflection data complemented by anal

holocene paleomagnetic secular variation from east china sea and a psv stack of east asia abstract paleomagnetic secular variation psv provides information on the mechanisms of the geodynamo and can also be used for stratigraphic correlation on a regional scale in this study we constructed psv curves of relative rapidly deposited holocene marine sequence from east china sea results show that the dominant magnetic carriers are pseudo single domain psd to multidomain md magnetites paleomagnetic directions are preserved by coarse grained magnetite even affected by post depositional diagenetic alteration the psv record of core md06 3040 exhibits six major inclination peaks and five declination swings during the holocene the periodicities for inclination are about 2000 and 550 years and for declination are about 1400 and 500 years the psv of md06 3040 is comparable to archeomagnetic and historic results for the last 2500 years and to psv results from lake sediments in southern china and japan during the holocene a psv stack of east asia is constructed by sedimentary and archeological psv results which can be used as an important reference curve for a large region and the psv correlation between sites can be applied for relative dating of east asia

large scale subaerial and submarine holocene and recent mass movements in the betsiamites area quebec canada abstract at least three major landslide events formed the submarine and subaerial betsiamites quebec canada landslide complex and mobilized an estimated total volume of 2000 million m3 2 km3 linkage between offshore and onshore geophysical investigations with borehole data and in situ testing allows reconstruction of the architecture of the betsiamites river delta area and leads to the identification of the main failure events the submarine scar of the betsiamites landslide complex may have resulted from a first failure dated at about 9250 cal bp which mobilized a minimum volume of 200 million m3 a second landslide dated at 7250 cal bp mobilized a volume of 1300 million m3 over an area of 54 km2 the betsiamites submarine landslide event dated at 7250 cal bp left the largest scar yet identified on the st lawrence estuary seafloor furthermore this paper demonstrates that the subaerial scar of the betsiamites landslide complex is a result of the colombier landslide event which was initiated by the 1663 earthquake and involved four successive failure phases one submarine and three subaerial the february 5th 1663 earthquake triggered a submarine landslide event which reached the shoreline and led in a short period of time successively to two subaerial flowslides in sensitive clayey material and a subaerial lateral spread the four failure phases mobilized a possible total volume of about 530 million m3 over an area of 20 km2 the colombier landslide event is among the largest documented historic landslides in canada the presence of submarine scars left by the early holocene events acted as predisposition factors for the development of the failure while the earthquake of 1663 was the main triggering factor of the first submarine failure

high resolution paleomagnetic records from laguna potrok aike patagonia argentina for the last 16 000 years 1 holocene and late glacial records documenting variations in direction and intensity of the geomagnetic field during the last 16 000 cal bp are presented for southern patagonia this continuous high resolution terrestrial record from laguna potrok aike 51 58 s 70 23 w was recovered within the salsa south argentinean lake sediment archives and modeling project mineral magnetic measurements indicate that pseudo single domain magnetite is the major carrier of the remanence allowing the reliable determination of stable natural remanent magnetization inclinations and declinations from alternating field demagnetization and principal component analysis paleomagnetic secular variation records reveal most of the familiar features of declination and inclination that have previously been reported in other records from south argentina but conspicuous centennial scale differences are also observed the results illustrate the potential of paleosecular variations records for dating sedimentary sequences in southern south america

south atlantic and north atlantic geomagnetic paleointensity stacks 0 80 ka implications for inter hemispheric correlation recent coring of high deposition rate atlantic sediments has led to the development of north atlantic napis and south atlantic sapis geomagnetic paleointensity stacks the sapis stack comprises five records from the sub antarctic south atlantic 41 471s 6 101e four are from piston cores collected during the ocean drilling program odp leg 177 site survey cruise earth planet sci lett 175 2000 145 the other is odp site 1089 leg 177 j geophys res 2001 submitted for publication all but one 4 pc03 of the sapis cores have oxygen isotope records which are used in conjunction with lithologic and geomagnetic variability to derive an optimized correlation to site 1089 the site 1089 age model is derived by mapping the benthic and planktic isotope data to those from nearby core rc11 83 which has 14 calibrated radiocarbon ages in the 11 41 ka interval below this level the chronology is derived by matching the site 1089 benthic oxygen isotope data to the specmap stack the napis stack comprises six records from a wide area of the north atlantic philos trans r soc ser a 358 2000 1009 correlation between cores was based on marine isotopic stage boundaries augmented by millennial scale features heinrich events and fluctuations in concentration dependent magnetic parameters napis was placed on the gisp2 chronology using the marine to ice core oxygen isotope correlation proposed by voelker et al radiocarbon 40 1998 517 for one of the napis cores in the resulting age model the laschampevent recorded in five of six cores falls in a very narrow o1 kyr age range and coincides with the 10 be and 36 cl peak measured in the ice cores comparison of the two stacks placed on their own independent age models indicates that common millennial scale paleointensity features are preserved although more work is needed to define the true global content of the paleointensity record as well as the precise age of many features it is readily apparent that paleointensity can provide a global correlation tool at a resolution unattainable from isotope data alone r 2002 published by elsevier science ltd

instability of partially saturated soil slopes due to alteration of rainfall pattern abstract the influence of climate change on rainfall patterns has the potential to alter stability of partially saturated soil slopes changes in rainfall patterns have a strong influence on stability of partially saturated soil slopes which recently have resulted in shallow landslides in this paper slope stability is assessed using a monolithically coupled finite element model for a deformable partially saturated soil subjected to surface infiltration of water numerical analysis solves for the matric suction distribution over a two dimensional cross section of a soil slope while varying permeability and considering a surface layer of soil with different permeability the formulation of hydraulic conductivity for a coupled analysis includes dependence on porosity and degree of saturation to illustrate the effects of water infiltration and deformation behavior in partially saturated soils numerical examples demonstrate that change in rainfall patterns may trigger slope instability earlier in the rainfall event than for rainfall events of the past assessment of these simulations can provide an indication of the potential influence of climate change on shallow landslides in many mountainous areas in south korea

high resolution paleomagnetic secular variation and relative paleointensity records from the western canadian arctic implication for holocene stratigraphy and geomagnetic field behaviourthis article is one of a series of papers published in this special issue on the theme polar climate stability network geotop contribution 2008 0024 two piston cores recovered from the chukchi and the beaufort seas document arctic holocene geomagnetic field behaviour and highlight the potential of secular variation and relative paleointensity as a regional chronostratigraphic tool several centennial to millennial scale holocene declination and inclination features can be correlated in both cores with other high resolution western north american lacustrine and volcanic paleomagnetic records and with records of changes in earth s dipole moment supporting the geomagnetic origin of these features and implying that they are associ ated with changes in earth s dipole moment resume deux carottes sedimentaires prelevees dans les mers de beaufort et de chukchi ont permis de reconstruire les variations d intensiteet d orientation de haute resolution du champ magnetique terrestre au cours de l holocene afin de caracteriser le comportement du champ geomagnetique dans l arctique ainsi que d explorer la possibilited utiliser les variations du champ geomagnetique comme outil chronostratigraphique au cours de l holocene la declinaison et l incli naison magnetique des deux sequences etudiees peuvent etre correlees entre elles avec des enregistrements paleomagne tiques lacustres ou volcaniques de l ouest de l amerique du nord a des echelles de temps au moins seculaires les variations de paleointensiterelative des deux carottes analysees sont egalement coherentes avec des enregistrements des variations du dipole geomagnetique confirmant ainsi l origine geomagnetique de ces variations et suggerant leur nature di polaire

model for the prediction of shear strength with respect to soil suction experimental studies on unsaturated soils are generally costly time consuming and difficult to conduct shear strength data from the research literature suggests that there is a nonlinear increas

the marine record of deglaciation from the continental margin off nova scotia continental margin sediments off nova scotia accumulate at high rates up to 360 cm kyr 1 and contain a history of millennial scale environmental changes which are dominated by the proximity of the laurentide ice sheet during the latest quaternary using stable isotope ratios of oxygen accelerator mass spectrometer radiocarbon dating micropaleontology and sedimentology we document these changes in six piston cores ranging in water depth from 450 to 4300 m we find that maximum 18o in n pachyderma occurred about 15 ka and preceded the maximum abundance of this species in these cores by 1000 years between 13 and 14 ka we find a second peak in abundance of n pachyderma minimum 18o and two pulses of ice rafting the sediment lithology supports terrestrial studies which indicate that there was a general withdrawal of ice beyond the upper paleozoic and mesozoic red beds by 14 ka in southeastern canada so the ice rafting events between 13 and 14 ka probably reflect ice stream activity in the st lawrence valley the younger dry as event is recognized as a peak in abundance of n pachyderma and ice rafting dated as 11 3 ka but meltwater discharge to the gulf of st lawrence was either too small or occurred over too long a time to leave a distinct 18o minimum off nova scotia at 7 1 ka in the middle of holocene warming we find a third peak in abundance of n pachyderma and another 18o minimum but no ice rafting we interpret these data as evidence of a late occurring meltwater event which if correct could have originated in the great lakes in the labrador ungava region or in both the final millennial scale phenomenon off nova scotia is the onset of neoglaciation marked by increased ice rafting and increased n pachyderma beginning about 5 kyr ago

are paleomagnetic records from u channels appropriate for studies of reversals and excursions sampling of sediment cores using plastic u channels has made possible the acquisition of detailed records of paleomagnetic secular variation geomagnetic polarity environmental magnetic studies and relative paleointensity over the past several million years u channel measurements provide the great advantage of rapid measurements of long sediment cores but the signal resolution is attenuated by the response function of the magnetometer sensors which therefore restrains the recovery of rapid and large amplitude field changes here we focus on the suitability of the dynamics of reversals and excursions derived from u channel measurements we compare successive individual paleomagnetic directions of 1 5 cm 1 5 cm 1 5 cm cubic discrete samples with those of a 1 5 m equivalent u channel sample train obtained by placing the samples adjacent to each other we use varying excursion and transition lengths and generate transitional directions that resemble those of the most detailed paleomagnetic records excursions with opposite polarity directions recorded over less than 7 5 cm are barely detected in u channel measurements regarding reversals u channel measurements smooth the signal of low resolution records and generate artificial transitional directions despite producing misleading similarities with the overall structure of transition records longer transitional intervals fail also to reproduce the complexity of field changes finally we test the convolution of magnetization by different response functions the simulation reveals that even small response function changes can generate significant differences in results keywords geomagnetic reversals geomagnetic excursions paleomagnetic measurements

a comparison of holocene paleomagnetic secular variation records from north america the comparison of nine holocene 0 12 000 years b p records of paleomagnetic field secular variation psv obtained from across north america indicates that distinctive field features in inclination and declination often can be traced for more than 4000 km without significant change in pattern independent age determinations corroborate these correlations while also suggesting that westward or eastward drift is not significant on the other hand northward drift may be a significant process at least between 1500 and 5500 years b p several methods of analyzing the overall psv character point to circularity vector looping as a preferred means of defining coherent space time vector variations which are termed waveforms a few distinctive waveforms each discernible for about 1400 years dominate psv across north america during the holocene 4 5 loops and 2 loops being associated with clockwise and counterclockwise circularity respectively the clockwise loops appear to be periodic occurring every 2400 years and most likely result from the recurrence of a distinctive regional dynamo source in the outer core the pattern of circularity noted in north america during the last 3000 years correlates in time with similar circularity changes seen globally this may indicate that there is some degree of coupling between different regional dynamo sources within the outer core the fact that some north american waveforms are almost identical to waveforms observed elsewhere around the world at different times may indicate that similar distinctive regional dynamo sources recur randomly throughout the outer core

a high resolution holocene paleomagnetic secular variation and relative paleointensity stack from eastern canada abstract a high resolution holocene paleomagnetic secular variation psv and relative paleointensity rpi stack was constructed using u channel paleomagnetic data from six radiocarbon constrained marine sedimentary sequences raised along the main axis of the laurentian channel eastern canada from its head to its mouth centennial to millennial scale declination and inclination features of the eastern canadian stack can be correlated within the dating uncertainties with other holocene north american icelandic and european psv records suggesting a common possibly hemispheric in character geomagnetic origin both magnetic inclination and declination of the eastern canadian stack are generally consistent with the time varying spherical harmonic model of the geomagnetic field cals7k 2 notably during the last 4000 cal bp in addition the eastern canadian holocene rpi stack reveals similar millennial and even centennial time scale variations consistent with some virtual axial dipole moment vadm reconstructions derived from absolute paleointensity data as well as with north american lacustrine rpi records accordingly these results suggest that the holocene paleomagnetic secular variation in north america is significantly driven by large scale 5000 km geomagnetic field changes at these timescales

solar activity reconstructed over the last 7000 years the influence of geomagnetic field changes 1 the long term solar activity as manifested by sunspot number has been recently reconstructed on multi millennium time scales by s k solanki et al 2004 from the measured concentration of 14 c in tree rings the exact level of the reconstructed solar activity depends however on independently evaluated data of the geomagnetic dipole strength variations recently a new series of the palaeomagnetic dipole moment reconstruction for the last 7000 years has been presented by m korte and c g constable 2005a on the basis of a thorough analysis of global samples the new palaeomagnetic series yields a systematically lower dipole moment in the past compared to the earlier geomagnetic reconstructions we have revised the earlier sunspot activity reconstruction since 5000 bc using the new geomagnetic data series and found that it is roughly consistent with the previous results during most of the period although the revised sunspot number values are in general higher nonetheless it is confirmed with the new palaeomagnetic series that the sun spends only 2 3 of the time in a state of high activity similar to the modem episode this strengthens the conclusion that the modem high activity level is very unusual during the last 7000 years

contrasting fates of organic matter in locations having different organic matter inputs and bottom water o 2 concentrations abstract the goals of this work were to study sedimentary organic matter om composition and transformation since the end of the last deglaciation and to evaluate the influence of contrasting depositional conditions on these parameters one station was located in the lower st lawrence estuary lsle where the current bottom waters are hypoxic and receive terrigenous and marine om the other station located in the gulf of st lawrence gsl has more oxygenated bottom waters and almost only marine om inputs analyses included enantiomers of amino acids l and d aa and muramic acid that provide different markers of om alteration state and reactivity and of bacterial contribution to om composition and diagenesis the markers clearly indicated the increase in om alteration state with depth in the sediments of the lsle and the gsl the steady decrease in aa yields with depth confirmed the preferential degradation of aa compared to the rest of the om the om in the surface sediment of the lsle was less altered than that of the gsl and was enriched in bacterial biomass as indicated by much higher muramic acid yields results indicated that an important degradation of particulate organic matter occurs in the water column in the gsl while it takes place mostly in the sediments in the lsle the presence of heterogeneous om and hypoxic conditions in the lsle likely reduce om degradation rate in its deep water layer however the zone near the water sediment interface is responsible for large variations in aa composition at both locations a relatively new redox index based on aa composition was tested and appeared robust this study highlights the importance of ambient conditions in determining the fate of om and in the biogeochemical cycles of vital elements

a 17 000 yr paleomagnetic secular variation record from the southeast alaskan margin regional and global correlations high resolution sedimentary records on two cores from the gulf of alaska margin allow development of a 17 400 yr reconstruction of paleomagnetic secular variation psv general agreement between the two records on their independent chronologies confirms that local psv is recorded demonstrating that such archives notwithstanding complexities due to variable sedimentary regimes deposition rates and diagenetic conditions provide meaningful information on past changes of the geomagnetic field comparisons with other independently dated sedimentary paleomagnetic records from the ne pacific indicate largely coherent inclination records that in combination create a ne pacific sedimentary inclination anomaly stack nepsias capturing the common signal over an area spanning 30 longitude and latitude from alaska through oregon to hawaii comparisons of nepsias with high quality declination records from the northern north atlantic nna show that negative shallow inclination anomalies in nepsias are associated with eastward nna declinations while positive steep inclination anomalies in nepsias are associated with westward nna declinations comparison of these directional records to regional geomagnetic intensities over the past 3000 yrs in north america and back nearly 8000 yrs in the euro mediterranean region are consistent with a driving mechanism of oscillations in the relative strength of the north american and euro mediterranean flux lobes the persistence of these dynamics through the holocene implicates a long lived organizing structure likely imposed on the geomagnetic field by the lower mantle and or inner core these observations underscore a fundamental connection between directional psv in the north pacific with that of the north atlantic supporting the potential for long distance correlation of directional psv as a chronostratigraphic tool

infinite slope stability under steady unsaturated seepage conditions 1 we present a generalized framework for the stability of infinite slopes under steady unsaturated seepage conditions the analytical framework allows the water table to be located at any depth below the ground surface and variation of soil suction and moisture content above the water table under steady infiltration conditions the framework also explicitly considers the effect of weathering and porosity increase near the ground surface on changes in the friction angle of the soil the factor of safety is conceptualized as a function of the depth within the vadose zone and can be reduced to the classical analytical solution for subaerial infinite slopes in the saturated zone slope stability analyses with hypothetical sandy and silty soils are conducted to illustrate the effectiveness of the framework these analyses indicate that for hillslopes of both sandy and silty soils failure can occur above the water table under steady infiltration conditions which is consistent with some field observations that cannot be predicted by the classical infinite slope theory a case study of shallow slope failures of sandy colluvium on steep coastal hillslopes near seattle washington is presented to examine the predictive utility of the proposed framework

geomagnetic evolution 400 years of change on planet earth abstract spherical harmonic coefficients of the geomagnetic field calculated from historical observations of declination inclination and intensity and from archaeomagnetic inclination results have been used to produce a film of geomagnetic change since 1600 a d the non dipole geomagnetic field is found to be constantly changing no fixed or standing non dipole features are observed non dipole foci are seen to have lifetimes of a few hundred years the westward drift which was an important feature of the 18th and early 19th century geomagnetic field was less pronounced in the 17th century the growth evolution decay and replacement of non dipole foci but not their movement are found to have been the major features producing century long secular directional magnetic variation most of the low degree and order spherical harmonic coefficients have changed significantly over the last few hundred years in particular the change in sign of the axisymmetric quadrupole around 1837 a d is noted sustained century long intensity changes however appear to have been dominated by variations in the intensity of the centred dipole rather than by non dipole field fluctuations

identification and dating of a key late pleistocene stratigraphic unit in the st lawrence estuary and gulf eastern canada abstract a recently acquired 8 m long sediment core along with high resolution seismic reflection and subbottom profiler sections allowed the identification characterization and dating of a widespread seismic unit extending from the head of the laurentian channel lower st lawrence estuary to honguedo strait gulf of st lawrence eastern canada this seismic unit labelled unit 2 is characterized by a series of parallel high amplitude reflections with thicknesses ranging from 68 m near the head of the laurentian channel to 250 m in the st lawrence estuary leaving it very difficult to be reached by conventional coring operations here we reveal how we were able to trace and core this seismic unit in an area where it lays closer to the seafloor near the southern wall of the laurentian channel in the lower st lawrence estuary this seismic unit consists of two sedimentary facies sandy mud including ice rafted debris ird underlying faintly laminated to homogenous and plastic silty clays based on the sedimentary facies we interpret the upper clays as ice distal glaciomarine sediments and the lower sandier sediments as ice proximal glaciomarine sediments this interpretation is further supported by the fact that no seismic nor sediment facies present above seismic unit 2 throughout the estuary and gulf of st lawrence can be linked to glacial i e ice contact sediments such as till moraines esker etc sediments seismic unit 2 is highly disturbed by iceberg scouring in the gulf of st lawrence where it is found at shallower depths indicating that it was deposited during deglaciation the available ams 14c dates obtained in the ice proximal glaciomarine sediments indicate that the lower part of seismic unit 2 was deposited during local re advances or stillstands of the laurentide ice sheet margins in the goldthwait sea that began at or before the younger dryas cold event 11 100 10 000 yr bp and that seismic unit 2 can be used as a chronostratigraphic marker throughout the st lawrence estuary and northwestern gulf of st lawrence

palaeoenvironmental history of the last six centuries in the nettilling lake area baffin island canada a multi proxy analysis the baffin island region in the eastern canadian arctic has recently experienced a rapid warming possibly unprecedented in millennia to investigate theresponse of freshwater environments to this warming and place it in a secular perspective we analyzed a 90 cm long sediment core from nettilling lake the largest lake of the canadian arctic archipelago the core was taken from a part of the lake basin that receives meltwater and sediment inputs from thenearby penny ice cap the core time scale established using 137cs and palaeomagnetic techniques spans an estimated 600 years a multi proxy approachwas used to document changes in the physical chemical and biological properties of the sediments we found evidence for a relatively warm period mid late 15th century to mid late 16th century during the early part of the little ice age lia characterized by high sedimentation rates and laminations this was followed by colder drier and windier conditions corresponding to the coldest phase of lia and coinciding with the latest and most extensiveperiod of regional ice cap expansion early 16th to late 19th centuries a rapid warming occurred at the beginning of the 20th century variations intitanium ti content in the core a proxy for detrital sediment inputs showed good agreement with reconstructed secular variations in summer meltrates on penny ice cap between the mid 14th century and the present day providing supporting evidence for a climatic hydrological connection betweenthe ice cap and nettilling lake

a 2000 year geomagnetic field record from the gulf of papua abstract a high resolution holocene record of geomagnetic field direction and intensity in the gulf of papua was constructed using paleomagnetic data from eight piston cores collected in the region the chronology of the cores was based largely on radiocarbon dates from benthic foraminifera correlation of seismic reflectors imaged in subbottom data between nearby cores was consistent with the chronostratigraphic framework based on radiocarbon dates and provided additional confidence of the age model in other regions where cores sampled different depositional settings associated with the three dimensional prograding lobes reflectors could not be confidently correlated between cores furthermore radiocarbon ages from the bottoms of trigger cores and tops of co located piston cores revealed varying amounts of overpenetration of the piston core below the seafloor the relative paleointensity and a general eastward trend in the declination and steepening of the inclination in our new record are generally compatible with the closest 4300 km existing records our record does not agree well with global field models cals3k and pfm9k likely reflecting the lack of existing data contributing to field models in the region

paleomagnetic secular variation and relative paleointensity during the holocene in south china huguangyan maar lake revisited the scarcity of reliable paleomagnetic secular variation psv records from east asia especially from low latitude regions impedes better understanding of global psv mechanisms here we report on a radiocarbon dated holocene psv record from a composite 6 7 m long core collected from the high sedimentation rate huguangyan maar lake hml in subtropical tropical south china rock magnetic results demonstrate that the natural remanent magnetization resides in single domain magnetite alternating field demagnetization experiments at 1 cm spacing on u channel samples reveal six distinct inclination highs at 7 500 bce 5 100 bce 4 600 bce 3 600 3 400 bce 1 600 1 200 bce and 600 800 ce three inclination lows at 4 800 bce 600 300 bce and 1 000 1 300 ce and three eastward declination trends at 3 600 3 200 bce 2 600 2 400 bce and 400 bce to 200 ce the similarity between the hml psv record and other independently dated records from east asia and geomagnetic field models corroborates the robustness of our age model and holocene psv record strikingly centennial to millennial scale psv features of the hml are comparable within age uncertainties with other holocene records from europe north america and canada suggesting that such directional patterns are likely to be hemispheric in scale although relative paleointensity data of hml are affected by environmental factors e g organic matter diagenesis the record still provides a regionally important new psv reference curve whose conspicuous features may serve as stratigraphic markers for east asian paleorecords

a new high resolution geomagnetic relative paleointensity record for the north american holocene a comparison of sedimentary and absolute intensity data a new high resolution paleointensity record for north america has been constructed using holocene sediments from lake pepin minnesota lake pepin sediments yield the same holocene paleosecular variation curve as nearby lake st croix and satisfy all of the criteria recommended for paleointensity studies absolute paleointensity data for north america recorded by holocene volcanic and archeomagnetic samples provide an independent record of geomagnetic field paleointensity against which the relative intensity records from lake pepin and lake st croix can be compared since the absolute field paleointensity is known a priori the effects of the magnetic recording assemblage can be isolated anhysteretic remanent magnetization arm is the best choice among normalization parameters for the lake pepin sediments as the natural remanent magnetization nrm normalized by arm shows no coherence with magnetic grain size proxies and yields a record of relative paleointensity peaks and troughs whose amplitudes are very similar to those in the archeomagnetic arcmag and lake st croix data sets features with a wavelength of 1000 years are correlative between the three paleointensity records nrm normalized by saturation isothermal remanent magnetization sirm and by susceptibility shows grain size dependences that cause errors in the amplitudes of paleointensity features nrm sirm and nrm are not coherent with their normalizers but are both strongly coherent with independent grain size proxies such as the median destructive field of the nrm and hcr we successfully removed the grain size dependences from nrm sirm by applying a correction function based on the linear relationship between normalized intensity and the median destructive field of the nrm

magnetic paleointensity stratigraphy and high resolution quaternary geochronology successes and future challenges abstract magnetic paleointensity stratigraphy is used to detect variations in the strength of earth s ancient magnetic field paleointensity studies have demonstrated that a dominantly dipolar geomagnetic signal can be recorded in a globally coherent manner in different types of sediments and in non sedimentary archives including ice core records and marine magnetic anomaly profiles the dominantly dipolar nature of geomagnetic paleointensity variations provides a global geophysical signal that has come to be widely used to date quaternary sediments despite the many successful applications of paleointensity assisted chronology the mechanisms by which sediments become magnetized remain poorly understood and there is no satisfactory theoretical foundation for paleointensity estimation in this paper we outline past successes of sedimentary paleointensity analysis as well as remaining challenges that need to be addressed to place such work on a more secure theoretical and empirical foundation we illustrate how common concepts for explaining sedimentary remanence acquisition can give rise to centennial to millennial offsets between paleomagnetic and other signals which is a key limitation for using paleointensity signals for geochronology our approach is intended to help non specialists to better understand the legitimate uses and limitations of paleointensity stratigraphy while pointing to outstanding problems that require concerted specialist efforts to resolve

influence of rainfall induced wetting on the stability of slopes in weathered soils abstract shallow failures of slopes in weathered soil are caused by infiltration due to prolonged rainfall these failures are mainly triggered by the deepening of the wetting band accompanied by a decrease in matric suction induced by the water infiltration this paper reports trends of rainfall induced wetting band depth in two types of weathered soils that are commonly found in korea both theoretical and numerical analyses for wetting band depth are presented based on the soil water characteristic curve obtained using filter paper as well as tensiometer tests it is found that the magnitude of wetting front suction plays a key role in the stability of slopes in weathered soils theoretical analysis based on modified green and ampt model tends to underestimate the wetting band depth for typical korean weathered soils it was also deduced that for korean weathered soils the factor of safety drops rapidly once the wetting band depth of 1 2 m reached

geochemical and geophysical implications of the radiocarbon calibration abstract a precise and accurate chronological framework is crucial to study the dynamics of a variety of phenomena which occurred during the last 45 000 years although the 14 c dating method has been widely applied since the 1950s it is recognized that the atmospheric 14 c 12 c ratio has not been stable during the past in order to calculate accurate ages these fluctuations have to be corrected by means of a calibration curve obtained by comparing raw 14 c measurements with true calendar ages provided by independent dating methods the calibration curve obtained so far is characterized by a long term trend with raw 14 c ages being significantly younger than calendar ages during most of the last 45 000 years abrupt 14 c shifts which occurred over centuries to millennia are superimposed on this long term trend of decreasing atmospheric 14 c 12 c ratio to a certain extent it is possible to outline the different causes of atmospheric 14 c variations by considering complementary information obtained from other cosmogenic nuclides studied at different latitudes 1 most high frequency changes in the atmospheric 14 c 12 c ratio are linked to magnetic fluctuations of solar origin as revealed by studying the last three centuries for which direct observations of the sun are available a similar conclusion is derived by comparing 14 c 12 c events with 10 be and 36 cl concentration maxima in polar ice cores 2 the long term trend shift of 14 c ages is due to a long period of decreased shielding effect of the geomagnetic dipole field which occurred over the interval between 10 000 and 40 000 years bp this interpretation is supported by paleomagnetic measurements performed on volcanic and sedimentary rocks and by 10 be and 36 cl analysed in low and high latitude records 3 a prominent and rapid atmospheric 14 c 12 c excursion occurred between 13 000 and 11 500 cal yr bp thus corresponding to the younger dryas cold period by contrast with the 14 c variability mentioned above which is linked to 14 c production changes this so called 14 c age plateau is probably due to an abrupt variation in the rates of exchange within the global carbon cycle this interpretation is supported by independent geochemical proxies and by numerical modelling of the carbon cycle

continuous geomagnetic field models for the past 7 millennia 1 a new global data compilation 1 a global data set of archeomagnetic and paleomagnetic data covering the past 7000 years has been compiled it consists of 16 085 results of inclination 13 080 of declination and 3188 of intensity for the time span 5000 bc to 1950 ad declination and inclination data come partly from existing databases and partly from original literature a new global compilation of intensity data for the millennial scale is included data and dating uncertainties are discussed as we attempted to obtain an internally coherent data set the global distribution of the data is very inhomogeneous in both time and space all the data are compared to predictions from the previous 3000 year global model cals3k 1 this collection of data will be useful for global secular variation studies and geomagnetic field modeling although southern hemisphere data are still underrepresented in particular we will use it in a further study to update and extend the existing global model cals3k 1 the huge increase in data compared to the previous compilation will result in significant changes from current models as we might have missed some suitable data we encourage the reader to notify us about any data that have not been included yet and might fit in as improving our global millennial scale models remains our aim for the future the data files described in this paper are available from the earthref digital archive erda at http earthref org cgi bin erda cgi n 331

engineering characteristics of ankara greywacke under the foundation of the beytepe open air theatre ankara turkey the construction of a large open air theatre having with an audience capacity of 7 000 is planned at the beytepe campus of hacettepe university located near ankara turkey in the heart of anatolia the foundation of the open air theatre is composed of weak and heavily jointed ankara greywacke an estimation of the strength and deformation of the ankara greywacke was required for assessments of short and long term stability accordingly rock mass characterization of the ankara greywacke was investigated in detail by scan line surveys and back analyses of in situ tests performed on the excavated surface of the rock mass the final version of the hoek and brown criterion hoek et al in proceedings of the north american rock mechanics society meeting toronto canada pp 1 6 2002 together with and improvements proposed by sonmez and gokceoglu int j rock mech min sci 43 671 676 2006 were considered together for the back analyses of small slope benches subjected to plate loading test loaded to failure in addition the plate loading test data were used with some well known empirical equations for predicting of deformation modulus of rock masses to calculate ranges of values of the geological strength index gsi the static and pseudostatic slope stabilities of the audience seating structures to be supported by benches excavated into the rock were also analyzed the stability assessments revealed the unlikelihood of large rock mass failures for the short term construction stages or for the long term as constructed conditions under static or pseudo static conditions additionally the analyses showed that there was no need for anchors between the concrete seating structures and greywacke rock mass

lake sediment record of the geomagnetic secular variation in britain during holocene times summary a palaeomagnetic record of the geomagnetic secular variation during the last 10000 years has been obtained from 10 cores of sediment from loch lomond scotland lake windermere north england and llyn geirionydd north wales a time scale is provided by 30 radiocarbon age determinations and pollen analyses on several of the cores the main swings and much fine detail of both declination and inclination records repeat well between cores and between lakes and the overall record is much more detailed than previous european records the new record shows that neither declination nor inclination swings have been periodic over the past 10000 years but that the main swings have become progressively shorter in duration during that time each swing is characterized by fine detail which enables use of the record as a secondary method of dating other european sediments the motion of the geomagnetic vector has been predominantly clockwise throughout the time period spanned but confirms a period of anticlockwise motion from 1100 to 600 bp first discovered by british archaeomagnetic investigations the record agrees with british and czechoslovakian archaeomagnetic records but not with japanese archaeomagnetic or north american lake sediment records this suggests that the secular changes are controlled by local growing and decaying drifting sources rather than by wobbling of the main geomagnetic dipole

development of an initiation criterion for debris flows based on local topographic properties and applicability assessment at a regional scale abstract damages caused by landslides have been increasing because of the greater frequency of localized heavy rain to prevent landslide disasters more efficiently more studies in relation to predicting the initiation areas of debris flows that cause large scale damage are necessary the main purpose of this study is to develop a criterion for detecting debris flow initiation areas by using an empirical method that was chosen from several types of approaches to debris flow initiation detection in this study ten gis based geomorphological datasets were obtained from slide and debris flow initiation areas located in seoul gyeonggi province and gangwon province the geomorphological characteristics of slide and debris flow occurrence areas were analyzed through a comparative analysis to identify relationships between debris flow initiation and each topographic index an initiation criterion for debris flows based on the geomorphological characteristics was suggested using an artificial neural network ann model combined with a modified threshold for the relationship between slope and upslope contributing area to validate the suitability of the initiation criterion for debris flow sequential applications of slope failure analysis and debris flow initiation analysis were conducted on a case study site to simulate the actual debris flow events as a result of the debris flow initiation analysis the prediction capture rate of the debris flow initiation criterion was determined to be 88 9 debris flow initiation areas totaling 143 300 m2 were identified among 1 935 400 m2 of slope failure areas predicted in the slope failure analysis it is efficient to apply the debris flow initiation criterion in the debris flow simulation because slope failure areas are only partly transformed into debris flows

variations in the geomagnetic dipole moment during the holocene and the past 50 kyr all absolute paleointensity data published in peer reviewed journals were recently compiled in the geomacia50 database based on the information in geomagia50 we reconstruct variations in the geomagnetic dipole moment over the past 50 kyr with a focus on the holocene period a running window approach is used to determine the axial dipole moment that provides the optimal least squares fit to the paleointensity data whereas associated error estimates are constrained using a bootstrap procedure we subsequently compare the reconstruction from this study with previous reconstructions of the geomagnetic dipole moment including those based on cosmogenic radionuclides be 10 and c 14 this comparison generally lends support to the axial dipole moments obtained in this study our reconstruction shows that the evolution of the dipole moment was highly dynamic and the recently observed rates of change 5 per century do not appear unique we observe no apparent link between the occurrence of archeomagnetic jerks and changes in the geomagnetic dipole moment suggesting that archeomagnetic jerks most likely represent drastic changes in the orientation of the geomagnetic dipole axis or periods characterized by large secular variation of the non dipole field this study also shows that the holocene geomagnetic dipole moment was high compared to that of the preceding similar to 40 kyr and that similar to 4 10 22 am 2 appears to represent a critical threshold below which geomagnetic excursions and reversals occur c 2008 elsevier b v all rights reserved less

spatial probability assessment of landslide considering increases in pore water pressure during rainfall and earthquakes case studies at atsuma and mt umyeon abstract increased pore water pressure due to rainfall infiltration and cyclic loading is a major cause of slope instability many studies have been carried out to assess rainfall induced landslide spatial probability based on physical models combining hydrological models to analyze changes in pore water pressure on slopes due to rainfall however the generation of pore water pressure due to seismic loading is often disregarded during assessments of earthquake induced landslide susceptibility hence in this paper we propose a model to assess landslide spatial probability that takes into account increased pore water pressure during both rainfall and earthquakes the procedure for the proposed method includes two main steps in step 1 we analyze the change in the groundwater table due to rainfall infiltration and subsurface flow during rainfall in step 2 the slope safety factor is calculated using an infinite slope model considering the generation of excess pore water pressure under cyclic loading during earthquakes landslide spatial probability is established based on the slope factor of safety we validated the proposed model by analyzing rainfall earthquake induced landslide events occurring on september 6 2018 in atsuma town japan according to our results the area under the receiver operating characteristic curve of the atsuma landslide data is 82 4 and the true positive rate of unstable slope classification is 98 1 the proposed model was then applied to mt umyeon korea to assess the spatial probability of rainfall earthquake induced landslide our model classifies the likelihood of landslide occurrence according to four susceptibility levels high moderate low and very low we also compared our results to those of previous models and show that the proposed approach may provide reasonably accurate predictions of landslide spatial probability during rainfall and earthquake events

the influence of high latitude flux lobes on the holocene paleomagnetic record of iodp site u1305 and the northern north atlantic 1 paleomagnetic analysis and radiocarbon dating of an expanded holocene deep sea sediment sequence recovered by integrated ocean drilling program iodp expedition 303 from labrador sea site u1305 lat 57 28 5 n long 48 31 8 w water depth 3459 m provides insights into mechanisms that drive both paleomagnetic secular variation psv and magnetization acquisition in deep sea sediments seventeen radiocarbon dates on planktonic foraminifera define postglacial ca 8 ka sedimentation rates as ranging from 35 to 90 cm kyr alternating field af demagnetization of u channel samples show that these homogeneous sediments preserve a strong stable and consistently well defined component magnetization normalized remanence records pass reliability criteria for relative paleointensity rpi estimates assuming that the age of magnetization is most accurately defined by well dated psv records with the highest sedimentation rates allows us to estimate and correct for temporal offsets at site u1305 interpreted to result from postdepositional remanence acquisition at a depth of 20 cm comparisons indicate that the northern north atlantic psv and rpi records are more consistent with european than north american records and the evolution of virtual geomagnetic poles vgp are temporally and longitudinally similar to global reconstructions though with much larger latitudinal variation the largest deviations from a geocentric axial dipole gad are observed during times of the highest intensities in contrast to the usual assumption these observations are consistent with the idea that psv in the north atlantic and elsewhere during the holocene results from temporal oscillations of high latitude flux concentrations at a few recurrent locations

gis based prediction method of landslide susceptibility using a rainfall infiltration groundwater flow model this paper describes a physical based model to predict rainfall induced landsides special attention was given to the introduction of a gis based model ys slope model yonsei slope model which can evaluate the susceptibility of landslides the model has been improved by incorporating the combined effects of groundwater flow and rainfall infiltration into the raster model the two dimensional darcy s law was used to reflect the effect of groundwater flow in the soil slope and the modified green ampt model which is a one dimensional infiltration model was selected to capture the effect of rainfall infiltration into the soil mass these elements were integrated into the infinite slope stability model for a rainfall induced landslide the proposed model was verified by comparing the results from existing models as well as an actual slope failure case that occurred in korea with further study the ys model could be adopted as a prediction method for rainfall induced landslides

holocene paleomagnetic records from the st lawrence estuary eastern canada centennial to millennial scale geomagnetic modulation of cosmogenic isotopes two long holocene piston cores md99 2220 and md99 2221 were raised from the st lawrence estuary eastern canada because of the expanded holocene sediment sequence this location provides a u channel based paleomagnetic study supported by an accelerator mass spectrometry ams 14c chronology rock magnetic and sedimentological data indicates that these sediments provide a paleomagnetic directional secular variation psv and relative paleointensity rpi proxy records for the last 8500 cal bp sedimentation rates vary from 1 2 to 4 2 m kyr comparison of inclination and declination features with other north american holocene psv records are generally consistent and temporal offsets are within chronological uncertainties the normalized natural remanent magnetization intensity record a rpi proxy from the postglacial sediments of core 2220 compares favorably with north american and european holocene rpi records at millennial and even some centennial timescales comparisons between core 2220 rpi proxy and the 10be flux record from the greenland summit gisp2 ice core finkel and nishiizumi j geophys res 102 1997 26699 26706 and a 14c production rate record bond et al science 294 2001 2130 2136 suggest that geomagnetic modulation may control the millennial and even some centennial scale variability within cosmogenic isotope records this implies that the core 2220 rpi record reflects changes in global scale geomagnetic field at these timescales

analysis of topographic and climatic control on rainfall triggered shallow landsliding using a quasi dynamic wetness index abstract a model for the prediction of both topographic and climatic control on shallow landslide initiation processes in hilly mountainous terrain is proposed the model develops upon a theory for coupled shallow subsurface flow and landsliding of the soil mantle previously proposed by montgomery and dietrich water resour res 30 1994 1153 the model uses a quasi dynamic wetness index to predict the spatial distribution of soil saturation in response to a rainfall of specified duration the rainfall predicted to cause instability in each topographic element is characterised by duration and frequency of occurrence the incorporation of a rainfall frequency duration relationship into assessment of landslide hazard provides a practical way to include climate information into estimation of the relative potential for shallow landsliding the model is applied to a mountain experimental basin where high resolution digital elevation data are available the cordon catchment 5 km2 in north eastern italy an inventory of landslide scars is used to document sites of instability and to provide a test of model performance by comparing observed landslide locations with model predictions the model reasonably reproduces the observed distribution of landslides although spatial variability of soil properties and hydrologic complexities not accounted for by the model complicate prediction of where landslides occur within areas of similar topographic climatic control model predictions from the quasi dynamic model are compared with those provided by the steady state model water resour res 30 1994 1153 these results suggest that the quasi dynamic model offers significant improvement over the steady state model in predicting existing landslides as represented in the considered landslide inventory

high resolution holocene paleomagnetic secular variation records from bay of bengal abstract we present high resolution paleosecular variation psv records up to 8 cal kyr bp from three piston cores md161 8 md161 11 and md161 13 acquired in the krishna godavari kg basin bay of bengal during the holocene period high sedimentation rates are recorded at md161 8 38 8 248 3 cm kyr md161 11 137 336 cm kyr and md161 13 573 cm kyr rock magnetic data analysis suggests that the remanence signal is carried by titanomagnetite titanohematite grains in stable single domain ssd pseudo single domain psd state the psv records of md161 11 and md161 13 show good correlation in the uppermost sediments despite significant variation in the sedimentation rates however poor correlation of psv records is observed for the core md161 8 probably due to local effects paleoinclination records of md161 8 md161 11 and md161 13 show a low between 2 4 and 2 0 cal kyr bp an increase between 2 0 and 1 4 cal kyr bp and a decrease towards the present to varying degrees these trends can be observed in the other asian psv records of shuangchiling scl and biwa lakes however the magnitude of the observed inclination anomaly in kg basin is higher 40 compared to those reported from scl 25 and biwa 10 lakes paleodeclination records of md161 11 and md161 13 show a decline between 4 0 and 2 9 cal kyr bp an increase between 2 9 and 2 1 cal kyr bp a substantial decrease between 2 1 and 1 0 cal kyr bp and an increase towards the present similar trends can be observed in the other asian psv records of scl and biwa lakes with a minor age offset of 0 2 0 5 kyr the available models cals7k 2 and cals10k 1 are evaluated for their capability in predicting the inclination and declination anomalies from the asian regions the cals7k 2 model can predict most of the inclination anomalies while the cals10k 1 is unable to predict many of them the cals7k 2 model shows that the observed inclination anomalies can be attributed to the presence of a strong non axial dipolar magnetic field over the bay of bengal more psv records need to be constructed to better understand the anomalous non axial dipolar field over the bay of bengal

a holocene paleosecular variation record from 14c dated volcanic rocks in western north america 1 a paleosecular variation psv curve for western north america is presented on the basis of 94 virtual geomagnetic poles vgps from dated volcanic rocks sampled at 446 sites approximately 60 of the paleomagnetic database has been previously published a curve defined by spherical smoothed splines is fitted to the vgps ranked by the quality of the age determinations where the data density is highest between 3690 and 30 years before present b p a d 1950 between 7800 and 7050 years b p and between 14 060 and 12 700 years b p the younger segments of the curve derived from volcanic rocks are similar but less complex than other high resolution psv curves derived from lacustrine sediments particularly the record at fish lake oregon the psv record from lava flows psvl however is perhaps more reliable in its general shape and chronology because of the higher fidelity of volcanic rocks as magnetic field recorders and because of the greater density of 14c dates the new psvl record provides a partial holocene master curve for western north america and will be of particular value in dating geological and archeological materials using paleomagnetic directions

rainfall induced landslides by deficit field matric suction in unsaturated soil slopes landslides are mainly triggered by decrease in the matric suction with deepening the wetting band by rainfall infiltrations this paper reports rainfall induced landslides in partially saturated soil slopes through a field study a comprehensive analysis on umyeonsan mt landslides in 2011 was highlighted the incident involves the collapse of unsaturated soil slopes under extreme rainfall event fundamental studies on the mechanism and the cause of landslides were carried out a number of technical findings are of interest including the failure mechanism of a depth of soil and effect of groundwater flow the downward movement of wetting band and the increase of groundwater level based on this an integrated analysis methodology for a rainfall induced landslide is proposed in this paper that incorporates the field matric suction for obtaining hydraulic parameters of unsaturated soil the field matric suction is shown to govern the rate of change in the water infiltration for the landslide analysis with respect to an antecedent rainfall special attention was given to a one dimensional infiltration model to determine the wetting band depth in the absence of the field matric suction the results indicate that landslide activities were primarily dependent on rainfall infiltration soil properties slope geometries vegetation and groundwater table positions the proposed methodology has clearly demonstrated both shallow and deep seated landslides and shows good agreement with the results of landslide investigations