integration of ice core marine and terrestrial records for the australian last glacial maximum and termination a contribution from the oz intimate group the degree to which southern hemisphere climatic changes during the end of the last glacial period and early holocene 30 8 ka were influenced or initiated by events occurring in the high latitudes of the northern hemisphere is a complex issue there is conflicting evidence for the degree of hemispheric teleconnection and an unresolved debate as to the principle forcing mechanism s the available hypotheses are difficult to test robustly however because the few detailed palaeoclimatic records in the southern hemisphere are widely dispersed and lack duplication here we present climatic and environmental reconstructions from across australia a key region of the southern hemisphere because of the range of environments it covers and the potentially important role regional atmospheric and oceanic controls play in global climate change we identify a general scheme of events for the end of the last glacial period and early holocene but a detailed reconstruction proved problematic significant progress in climate quantification and geochronological control is now urgently required to robustly investigate change through this period copyright c 2006 john wiley sons ltd

space time distribution of small earthquakes at phlegraean fields south central italy a preliminary statistical analysis of the space time distribution of small seismic events in the volcanic area of phlegraean fields south central italy was done on the basis of a catalogue of earthquakes recorded by the local seismic stations in the period january 1 december 31 1983

a seismic source zone model for the seismic hazard assessment of the italian territory abstract we designed a new seismic source model for italy to be used as an input for country wide probabilistic seismic hazard assessment psha in the frame of the compilation of a new national reference map we started off by reviewing existing models available for italy and for other european countries then discussed the main open issues in the current practice of seismogenic zoning the new model termed zs9 is largely based on data collected in the past 10 years including historical earthquakes and instrumental seismicity active faults and their seismogenic potential and seismotectonic evidence from recent earthquakes this information allowed us to propose new interpretations for poorly understood areas where the new data are in conflict with assumptions made in designing the previous and widely used model zs4 zs9 is made out of 36 zones where earthquakes with m w 5 are expected it also assumes that earthquakes with m w up to 5 may occur anywhere outside the seismogenic zones although the associated probability is rather low special care was taken to ensure that each zone sampled a large enough number of earthquakes so that we could compute reliable earthquake production rates although it was drawn following criteria that are standard practice in psha zs9 is also innovative in that every zone is characterised also by its mean seismogenic depth the depth of the crustal volume that will presumably release future earthquakes and predominant focal mechanism their most likely rupture mechanism these properties were determined using instrumental data and only in a limited number of cases we resorted to geologic constraints and expert judgment to cope with lack of data or conflicting indications these attributes allow zs9 to be used with more accurate regionalized depth dependent attenuation relations and are ultimately expected to increase significantly the reliability of seismic hazard estimates

the last glacial maximum in central and southern north island new zealand a paleoenvironmental reconstruction using the kawakawa tephra formation as a chronostratigraphic marker abstract kawakawa tephra formation comprising oruanui ignimbrite flow member and aokautere ash airfall member represents the products of an exceptionally large and widespread volcanic eruption from taupo volcanic centre in the north island of new zealand the eruption occurred during the last glacial maximum and is radiocarbon dated at c 22 6 ka b p thermoluminescence ages are in broad agreement with the radiocarbon age the presence of aokautere ash in loess deposits in alluvial gully fills on river terraces and its absence from unstable sites permits a detailed assessment of geomorphic activity during the last glacial maximum widespread erosion of regolith aggradation of river valleys and deposition of loess particularly in the period following eruption of the kawakawa point to a cold dry variable climate a collation of pollen data for sediments containing aokautere ash and those 14c dated in the range 17 23 ka shows that tall forest was highly restricted in the central and southern parts of the north island an apparently subalpine grassland shrubland was present at sites from present sea level to over 800 m elevation suggesting that factors other than lower temperatures such as exposure to wind and frost fire and reduced rainfall were important in controlling vegetation patterns we conclude that the interval 23 13 ka b p broadly equivalent to oxygen isotope stage 2 represents the period of greatest environmental change in the north island

towards a climate event stratigraphy for new zealand over the past 30 000 years nz intimate project it is widely recognised that the acquisition of high resolution palaeoclimate records from southern mid latitude sites is essential for establishing a coherent picture of inter hemispheric climate change and for better understanding of the role of antarctic climate dynamics in the global climate system new zealand is considered to be a sensitive monitor of climate change because it is one of a few sizeable landmasses in the southern hemisphere westerly circulation zone a critical transition zone between subtropical and antarctic influences new zealand has mountainous axial ranges that amplify the climate signals and consequently the environmental gradients are highly sensitive to subtle changes in atmospheric and oceanic conditions since 1995 intimate has through a series of international workshops sought ways to improve procedures for establishing the precise ages of climate events and to correlate them with high precision for the last 30 000 calendar years the nz intimate project commenced in late 2003 and has involved virtually the entire new zealand palaeoclimate community its aim is to develop an event stratigraphy for the new zealand region over the past 30 000 years and to reconcile these events against the established climatostratigraphy of the last glacial cycle which has largely been developed from northern hemisphere records e g last glacial maximum lgm termination i younger dryas an initial outcome of nz intimate has been the identification of a series of well dated high resolution onshore and offshore proxy records from a variety of latitudes and elevations on a common calendar timescale from 30 000 cal yr bp to the present day high resolution records for the last glacial coldest period lgcp including the lgm sensu stricto and last glacial interglacial transition lgit from auckland maars kaipo and otamangakau wetlands on eastern and central north island marine core md97 2121 east of southern north island speleothems on northwest south island okarito wetland on southwestern south island are presented discontinuous fragmentary records comprising compilations of glacial sequences fluvial sequences loess accumulation and aeolian quartz accumulation in an andesitic terrain are described comparisons with ice core records from antarctica epica dome c and greenland gisp2 are discussed a major advantage immediately evident from these records apart from the speleothem record is that they are linked precisely by one or more tephra layers based on these new zealand terrestrial and marine records a reasonably coherent regionally applicable sequence of climatically linked stratigraphic events over the past 30 000 cal yr is emerging three major climate events are recognised 1 lgcp beginning at ca 28 000 cal yr bp ending at termination i ca 18 000 cal yr bp and including a warmer and more variable phase between ca 27 000 and 21 000 cal yr bp 2 lgit between ca 18 000 and 11 600 cal yr bp including a lateglacial warm period from ca 14 800 to 13 500 cal yr bp and a lateglacial climate reversal between ca 13 500 and 11 600 cal yr bp and 3 holocene interglacial conditions with two phases of greatest warmth between ca 11 600 and 10 800 cal yr bp and from ca 6 800 to 6 500 cal yr bp some key boundaries coincide with volcanic tephras copyright 2007 john wiley sons ltd

340 000 year centennial scale marine record of southern hemisphere climatic oscillation in order to investigate rapid climatic changes at mid southern latitudes we have developed centennial scale paleoceanographic records from the southwest pacific that enable detailed comparison with antarctic ice core records these records suggest close coupling of mid southern latitudes with antarctic climate during deglacial and interglacial periods glacial sections display higher variability than is seen in antarctic ice cores which implies climatic decoupling between mid and high southern latitudes due to enhanced circum antarctic circulation structural and temporal similarity with the greenland ice core record is evident in glacial sections and suggests a degree of interhemispheric synchroneity not predicted from bipolar ice core correlations

estimating ages of late quaternary stream terraces from analysis of weathering rinds and soils rates of growth of rock weathering rinds and rates of changes of soil morphologic and chemical properties that are calibrated at sites of known ages produce powerful tools for estimating ages of geomorphic surfaces particularly when materials datable by conventional methods are not widespread sequences of latest quaternary stream terraces from the south island of new zealand are ideally suited for application of these calibrated age techniques because climate and source materials for terrace deposits are internally consistent within two regions west land and marlborough modal and mean thicknesses of weathering rinds formed in surface cobbles of torlesse graywacke provide age estimates for latest pleistocene and holocene stream terraces in marlborough with uncertainties estimated at 5 to 40 modal rind thickness of subsurface cobbles provides age estimates for latest quaternary westland sites with uncertainties of 10 to more than 50 few dated soils are available to constrain rates of soil development in westland and marlborough furthermore soils were sampled from only one pedon on each surface morphologic data however provide least squares age estimates for westland sites with uncertainties typically greater than 100 and the calibration data can further bracket likely soil ages to less than 50 uncertainty the regression data from marlborough are less reliable but profile index ratios help bracket ages to at least 50 distributions of oxalate extractable fe and ai and total major element concentrations allow age estimates for westland and marlborough soils with uncertainties estimated at 15 to 50 despite these uncertainties the three techniques combine to provide age estimates with the high resolution needed to examine details of fault slip rates or stream downcutting the calibration data and weathering rates used herein are applicable only to the new zealand region studied although similar calibrated age techniques should provide high resolution dating in many other regions such techniques are particularly useful when multiple approaches are available to provide independent cross checks

river response to an active fold and thrust belt in a convergent margin setting north island new zealand high resolution digital elevation data topsar 10 m grid are used to reconstruct late quaternary growth histories of subtle folding in the wairarapa fold and thrust belt north island new zealand outcrop data of deformed latest miocene and younger strata are combined with observations of warped and faulted late quaternary terrace surfaces to unravel the geomorphic and structural history of the huangarua river valley optically stimulated luminescence osl dating of loess that accumulated on these strath terraces and paleosol stratigraphy allow temporal correlation among the terraces and with glacial climate cycles since the last interglaciation these data indicate that five intervals of strath cutting occurred at 125 60 70 30 15 and 10 ka strath beveling is largely independent of local folding or regional base level change we hypothesize that straths are cut when an increase in sediment supply during cool climatic periods brings river sediment load and river transport capacity into balance in the wairarapa strath cutting events appear to occur near the end of cool climatic cycles this study shows that the identification of subtle departures from regional topographic trends becomes practical when a high resolution dem is available after subtraction of an average valley gradient from the digital topography the residual topography on the terrace treads reveals cross valley and longitudinal tilting although rates of folding are slow and the magnitude of deformation is commonly limited to less than a few tens of meters these topographic anomalies define fold axes that coincide with subsurface structures when combined with time control these anomalies serve to define the patterns and rates of fold growth over the past 125 kyears

luminescence chronology of late pleistocene glacial deposits in north westland new zealand abstract the chronology of the late pleistocene glacial history of north westland south island of new zealand is refined by luminescence dating of sediments it is demonstrated by two case studies that ages determined by different luminescence techniques agree well with the results of radiocarbon dating luminescence ages determined for sediments from two key sites of the loopline formation confirm the previous correlation of this unit with marine isotope stage mis 4 this indicates that late pleistocene glaciers reached their last maximum extent in north westland during the early part of the otira last glaciation furthermore initial dating evidence on coarse alluvial deposits in the lowlands indicates their formation during mis 5b and mis 5d it is probable that these coarse gravel deposits are outwash related to glacial advances if so both advances were probably much less extensive than the glaciations during mis 4 and mis 2

importance of mapping design earthquakes insights for the southern apennines italy probabilistic seismic hazard analysis is currently the soundest basis for the rational evaluation of ground motion hazard for site specific engineering design and assessment purposes an increasing number of building codes worldwide ac knowledge the uniform hazard spectra as the reference to determine design actions on structures and to select input ground motions for seismic structural analysis this is the case for example in italy where the new seismic code also requires the seismic input for nonlinear dynamic analysis to be selected on the basis of dominating events for example identified via disaggregation of seismic hazard in the present study the design earthquakes expressed in terms of representative magnitude m distance r and e were investigated for a wide region in the southern apennines italy to this aim the hazards corresponding to peak ground acceleration and spectral acceleration at 1 sec with a return period of 475 yr were disaggregated for each of the disaggregation variables the shape of the joint and marginal probability density functions were studied the first two modes expressed by m r and e were extracted and mapped for the study area the results shown provide additional information in terms of source and ground motion parameters to be used along with the standard hazard maps to better select the design earthquakes the analyses also allow us to assess how var ious frequency ranges of the design spectrum are differently contributed by seismic sources in the study area

seismic signals preceding the explosive eruption of mount st helens washington on 18 may 1980 abstract the intense seismic activity which preceded the 18 may 1980 eruption of mount st helens washington released 2 to 3 10 18 ergs day in earthquakes that did not correlate temporally with phreatic eruptions which occurred during the same period although the b value and amplitude ratios long period short period of the earthquakes vary with time there are no definitive precursors to the 18 may earthquake and eruption a mogi type ii frequency magnitude relation with critical magnitude mc 4 6 constrains the characteristic dimension of the highly stressed region under mount st helens to approximately 3 km preceding the eruption a major increase in seismic energy release and a decrease in b value around 1 april 1980 may indicate the first major influx of magma into the upper portion of the volcano seismic waves from low frequency volcanic earthquake have large periods at all epicentral distances recordings of volcanic earthquakes from 2 to 4 april 1980 at sites 4 to 9 km from mount st helens show two predominant periods of 0 55 and 1 0 sec we speculate that seismic signals from the low frequency volcanic earthquakes have a tectonic origin but may be modified by pressure oscillations in nearby magma

fine resolution pollen record of late glacial climate reversal from new zealand the temporal relationship between rapid climate shifts in the northern and southern hemispheres at the end of the last glacial is crucial to understanding how the global climate system functions during periods of major transition a detailed southern hemisphere mid latitude pollen record from a climatically sensitive and well dated upland site in new zealand unlike previous interpretations shows clear evidence of late glacial climate changes similar in structure to those in the northern hemisphere including a cooling interval from ca 11 600 to 10 700 14 c yr b p because the cooling interval occurred ca 600 14 c yr before the younger dryas chron our record thus also suggests that some global climatic events during the last deglaciation may have registered earlier in the southern hemisphere

relative timing of deglacial climate events in antarctica and greenland the last deglaciation was marked by large hemispheric millennial scale climate variations the bolling allerod and younger dryas periods in the north and the antarctic cold reversal in the south a chronology from the high accumulation law dome east antarctic ice core constrains the relative timing of these two events and provides strong evidence that the cooling at the start of the antarctic cold reversal did not follow the abrupt warming during the northern bolling transition around 14 500 years ago this result suggests that southern changes are not a direct response to abrupt changes in north atlantic thermohaline circulation as is assumed in the conventional picture of a hemispheric temperature seesaw

assessment of pre crisis and syn crisis seismic hazard at campi flegrei and mt vesuvius volcanoes campania southern italy in this study we address the issue of short term to medium term probabilistic seismic hazard analysis for two volcanic areas campi flegrei caldera and mt vesuvius in the campania region of southern italy two different phases of the volcanic activity are considered the first which we term the pre crisis phase concerns the present quiescent state of the volcanoes that is characterized by low to moderate seismicity the second phase syn crisis concerns the unrest phase that can potentially lead to eruption for the campi flegrei case study we analyzed the pattern of seismicity during the 1982 1984 ground uplift episode bradyseism for mt vesuvius two different time evolutionary models for seismicity were adopted corresponding to different ways in which the volcano might erupt we performed a site specific analysis linked with the hazard map to investigate the effects of input parameters in terms of source geometry mean activity rate periods of data collection and return periods for the syn crisis phase the analysis in the present study of the pre crisis phase allowed a comparison of the results of probabilistic seismic hazard analysis for the two study areas with those provided in the italian national hazard map for the mt vesuvius area in particular the results show that the hazard can be greater than that reported in the national hazard map when information at a local scale is used for the syn crisis phase the main result is that the data recorded during the early months of the unrest phase are substantially representative of the seismic hazard during the whole duration of the crisis

the kaharoa tephra as a critical datum for earliest human impact in northern new zealand the debate over the timing of arrival and earliest environmental impacts of the first new zealanders has intensified in recent years in part fuelled by new evidence or reinterpretation of old evidence from other points along prehistoric polynesian migratory routes an examination of two radiocarbon dated pollen records from northern new zealand shows how divergent interpretations could be drawn from the same evidence to support both early and late colonization models radiocarbon dated pollen records for deforestation at sites where the risk of contamination by older carbon may be high cannot be used to establish chronologies of settlement ombrogenous mires where peat accumulation proceeds independently of groundwater or surface runoff are likely to yield the most reliable records another solution applicable in northern new zealand is to base chronologies on tephra layers with reliable age estimates from multiple determinations analysis of 11 pollen records currently known to contain the 665 15 bp c 600 cal bp rhyolitic kaharoa tephra demonstrates the critical stratigraphic position that this isochronous surface occupies in new zealand prehistory the earliest inferred human impacts occurred at around the time of deposition of the tephra in eight of these sites 73 and well after it at the remainder these results are in agreement with a later colonization model and suggest that proximity to accessible food resources was more important than climate or latitude in determining early colonization sites these findings will be tested fully when the known range of kaharoa tephra is extended beyond its present limited range through the application of micro tephra analysis in line with anderson s 1995 128 premise that the later colonization model is eminently falsifiable we suggest that tephropalynological studies involving the kaharoa tephra may hold the key to resolving debates over the timing and spatial patterns of earliest human impact in northern new zealand in particular these records permit the investigator to avoid the ambiguities that emerge frequently when pollen profiles indicating deforestation are dated by radiocarbon alone

evidence against a significant younger dryas cooling event in new zealand pollen records of deglacial sequences from northwest nelson new zealand demonstrate that there was no significant temperature decline associated with the younger dryas in new zealand records of glacial advances at this time were either the product of increased snow accumulation under enhanced precipitation regimes or random variation rather than the result of a regional thermal decline this finding supports those models of younger dryas initiation that require neither enhanced westerly circulation nor significant thermal decline in the southern hemisphere

correlation of fluvial terraces within the hikurangi margin new zealand implications for climate and baselevel controls abstract a correlation of fluvial terraces is presented for eight non glacial catchments of the eastern north island new zealand within the actively uplifting hikurangi margin using a combination of loess and tephra coverbed stratigraphy and radiocarbon and osl dating of fluvial deposits and loess coverbeds we demonstrate correlation of four fill terraces t1 t4 the available age constraints suggest t1 15 30 ka t2 31 50 ka t3 50 70 ka and t4 115 ka but the association and temporal link with loess deposits suggest correlation with cold periods and thus the refinement of t2 late mis 3 31 40 ka t3 mis 4 55 70 ka t4 mi substage 5b 90 ka 5d 110 ka or mis 6 140 160 ka the ability to correlate terraces between catchments plus the lack of independent evidence for tectonic triggering events indicates terraces have probably formed in response to either climate terrestrial or baselevel sea level control climate control is indicated by the temporal link of post glacial incision with re establishment of forest cover and of lgm aggradation with limited grass and shrub cover and periglacial processes aggradation due to increased sediment supply under reduced vegetation is dramatically demonstrated by formation of the taupo pumice alluvium terrace in response to inundation by volcanic deposits unwelded ignimbrite following the 1 8 ka taupo eruption and the response to post settlement

stratigraphy chronology styles and dynamics of late quaternary eruptions from taupo volcano new zealand taupo volcano is the southerly of two dormant caldera volcanoes in the rhyolite dominated central portion of the taupo volcanic zone in the north island of new zealand taupo has an average magma output rate of 0 2 m 3 s 1 over the past 65 000 years and is one of the most frequently active and productive rhyolite volcanoes known the structure of the modern inverse volcano was formed largely by caldera collapse associated with the voluminous 22 600 14 c years bp oruanui eruption and has been little modified since except for collapse following the 1850 14 c years bp eruption the products of 28 eruptions labelled psi omega a ldots z all of which post date the oruanui eruption are defined and described here twenty seven of these eruptions are represented by pyroclastic deposits of which three were accompanied by a mappable lava extrusion and one eruption z solely by evidence for a lava extrusion the deposits of seven eruptions b c e s v x and y largely correspond to previously defined tephra formations karapiti poronui opepe waimihia whakaipo mapara and taupo respectively the previously defined motutere and hinemaiaia tephras are reinterpreted to represent the products of 12 eruptions g to r while the remaining eight deposits and one eruption are newly recognized eruption psi occurred at ca 17 200 14 c or 20 500 calibrated years bp and eruption z about 1740 calibrated years bp eruption volumes vary by more than three orders of magnitude between 0 01 and more than 44 km 3 and repose periods by more than two orders of magnitude from ca 20 to 6000 years the eruption deposits reflect great variations in parameters such as volume the dispersal characteristics of the fall deposits the presence or absence of intraeruptive time breaks the formation of pyroclastic flows the degree of magma water interaction the vesiculation state of the magma on fragmentation and the relative proportions of juvenile obsidian versus foreign lithologies in the lithic fractions all but seven fall deposits are plinian in dispersal two y1 and probably w are sub plinian one y5 has been termed ultraplinian while psi and a are too poorly preserved for their dispersal to be assessed the lengths of repose periods in the post oruanui sequence range are not randomly distributed but show self similar properties fractal dimensionality repose intervals r in years of not more than 350 years follow n 53 5r 0 21 and those of not less than 350 years follow n 2096r 0 83 where n is the number of eruptions the shorter repose periods may reflect triggering processes such as regional extension affecting magma bodies during their viable lifetimes while longer repose intervals i e not less than 350 years may reflect an episodicity of major rifting events or the production of magma bodies below the volcano bulk volumes v in km 3 of the eruption products also show self similar properties fractal dimensionality with n 6 17v 0 46 however there are then apparently random relationships between eruption volumes and the preceding or succeeding repose period such that prediction of the time and size of the next eruption is impossible the post oruanui activity at taupo represents noise superimposed on the more uniform longer term activity in the central taupo volcanic zone where large greater than 100 km 3 eruptions such as the oruanui occur at more evenly spaced intervals of one per 40 60 000 years

an event stratigraphy for the last termination in the north atlantic region based on the greenland ice core record a proposal by the intimate group it is suggested that the grip greenland ice core should constitute the stratotype for the last termination based on the oxygen isotope signal in that core a new event stratigraphy spanning the time interval from ca 22 0 to 11 5 k grip yr bp ca 19 0 10 0 k 14 c yr bp is proposed for the north atlantic region this covers the period from the last glacial maximum through termination 1 of the deep ocean record to the pleistocene holocene boundary and encompasses the last glacial late glacial of the traditional northwest european stratigraphy the isotopic record for this period is divided into two stadial episodes greenland stadials 1 gs 1 and 2 gs 2 and two interstadial events greenland interstadials 1 gi 1 and 2 gi 2 in addition gi 1 and gs 2 are further subdivided into shorter episodes the event stratigraphy is equally applicable to ice core marine and terrestrial records and is considered to be a more appropriate classificatory scheme than the terrestrially based radiocarbon dated chronostratigraphy that has been used hitherto 1998 john wiley sons ltd

holocene glacier variations in new zealand a review abstract in the central southern alps of new zealand ice surface lowering has exposed extensive sections of lateral moraines allowing investigation of moraine stratigraphy and genesis the presence of multiple superposed palaeosurfaces within moraine sequences allows recognition of any disturbances displacements or contamination of till layers and interbedded organic material radiocarbon dating of buried wood and soils allows comparison between the holocene glacial history of the eastern ranges and that of the westland region the periodicity of glacier response has been similar to both areas although the precise timing of events has differed due to local climatic and environmental factors in general glaciers in new zealand expanded about 5000 4500 4200 3700 3500 3000 2700 2200 1800 1700 1500 1100 900 700 600 and 400 100 bp

the 26 5 ka oruanui eruption new zealand an introduction and overview abstract the 26 5 ka oruanui eruption from taupo volcano in the central north island of new zealand is the largest known wet eruption generating 430 km3 of fall deposits 320 km3 of pyroclastic density current pdc deposits mostly ignimbrite and 420 km3 of primary intracaldera material equivalent to 530 km3 of magma erupted magma is 99 rhyolite and 90 pdc deposits range from mm to cm thick ultra thin veneers enclosed within fall material to 200 m thick ignimbrite in proximal areas the farthest travelled 90 km most energetic pdcs velocities 100 m s 1 occurred during phase 8 but the most voluminous pdc deposits were emplaced during phase 10 grain size variations in the pdc deposits are complex with changes seen vertically in thick proximal accumulations being greater than those seen laterally from near source to most distal deposits modern lake taupo partly infills the caldera generated during this eruption a 140 km2 structural collapse area is concealed beneath the lake while the lake outline reflects coeval peripheral and volcano tectonic collapse early eruption phases saw shifting vent positions development of the caldera to its maximum extent indicated by lithic lag breccias occurred during phase 10 the oruanui eruption shows many unusual features its episodic nature wide range of depositional conditions in fall deposits of very wide dispersal and complex interplay of fall and pdc activity

timing of millennial scale climate change in antarctica and greenland during the last glacial period a precise relative chronology for greenland and west antarctic paleotemperature is extended to 90 000 years ago based on correlation of atmospheric methane records from the greenland ice sheet project 2 and byrd ice cores over this period the onset of seven major millennial scale warmings in antarctica preceded the onset of greenland warmings by 1500 to 3000 years in general antarctic temperatures increased gradually while greenland temperatures were decreasing or constant and the termination of antarctic warming was apparently coincident with the onset of rapid warming in greenland this pattern provides further evidence for the operation of a bipolar see saw in air temperatures and an oceanic teleconnection between the hemispheres on millennial time scales

the last glacial interglacial transition lgit in south westland new zealand paleoecological insight into mid latitude southern hemisphere climate change abstract high resolution pollen stratigraphy from three peat cores located within 20 km of lateglacial moraines in south westland new zealand provide detailed records of climate change during the last glacial interglacial transition lgit the pollen record shows the replacement of grassland by shrubland prior to ca 15 300 14 c yr bp 18 300 cal yr bp followed by the progressive development of broadleaf shrubland and scattered forest prior to ca 12 000 14 c yr bp 14 400 cal yr bp local vegetation changes around the time of the younger dryas chronozone 11 10 ka 14 c bp are evident but are not necessarily a result of regional climate cooling vegetation changes between ca 12 000 and 10 000 14 c yr bp 14 400 and 11 400 cal yr bp indicate a period of increased precipitation tall podocarp forest similar to that of the contemporary forest was well established by ca 10 000 14 c yr bp 11 400 cal yr bp a period of increased westerly circulation over southern new zealand is considered to be the most likely mechanism for causing the increased precipitation between ca 12 000 and 10 000 14 c yr bp 14 300 and 11 400 cal yr bp increased precipitation would also provide a mechanism for initiating lgit ice advance in the area data from these records show some support for global climate change models that propose inter hemispheric linkage but may be more supportive of a climate change model that incorporates an increased westerly circulation over southern new zealand during the lgit

statistical analysis and clustering features of the phlegraean fields earthquake sequence may 1983 may 1984 abstract the seismic activity at the phlegraean fields volcanic area southern italy during the period may 1983 may 1984 5 301 selected events has been analyzed from a statistical point of view the analysis of the time series associated to the microearthquakes shows a high degree of interdependence among the events the main feature being the occurrence of dense swarms the generalized poisson process provides a good fit for the sequence the clustering of the events has not substantially changed during the analyzed period while the mean rate of occurrence of the swarms has generally increased the distribution of the magnitudes within the swarms shows pronounced maxima of energy around the center of the subsequences in agreement with theoretical models of fractures in highly heterogeneous media

dating the culmination of river aggradation at the end of the last glaciation using distal tephra compositions eastern north island new zealand an extensive terrace waipaoa 1 that can be traced for about 29 km in the waipaoa valley eastern north island new zealand is underlain by at least 10 m of coarse aggradational river gravels terrace cover beds contain tephras erupted from central north island volcanoes and these provide minimum ages for the underlying gravels tephra or tephric layers occurring in the lower cover beds were investigated at five sites using a combination of stratigraphy mineralogy and the major element composition of glass shards together with discriminant function analysis dfa the basal tephra is identified as the ca 14 700 14c years old ca 17 700 cal years b p rerewhakaaitu tephra erupted from okataina volcanic centre using the stratigraphic relationship of rerewhakaaitu tephra the end of aggradation is dated at ca 15 000 14c years ca 18 000 cal years correlation with aggradational terraces elsewhere in north island and northern south island indicates that aggradation ended at the same time over a wide area and confirms a climatic origin for the terraces subsequent downcutting was apparently rapid because rerewhakaaitu tephra also occurs at the base of cover beds on a ca 15 m lower terrace the downcutting represents a major change in river dynamics and is most likely the response to climatic change and the resultant upper catchment landscape stability

the timing of the last glacial maximum in australia abstract late pleistocene glaciation of australia was restricted to the snowy mountains and the tasmanian highlands glaciers were most extensive in tasmania where ice caps formed on the central plateau and west coast ranges and systems of valley and cirque glaciers formed on surrounding mountains to investigate the timing of maximum glacier advance during the last glacial maximum lgm we dated boulders on 18 moraines in 8 glaciated areas using cosmogenic 36cl and 10be we sampled moraines deposited by cirque and valley glaciers in a range of climate types and lithologies over a 7 latitudinal and a 1430 m altitudinal transect exposure ages for lgm moraine boulders group tightly in the range 17 20 ka boulders from the hamilton moraine often treated as the lgm type moraine range in age from 190 350 ka indicating that it was deposited well before the last glaciation collectively the exposure ages show that southeastern australia was glaciated briefly during and after the lgm and deglaciated well before the holocene ice retreated from the terminal moraines after the period of coldest sea surface temperatures in the southwest pacific ocean no evidence was found for readvance of glaciers during the antarctic cold reversal or the younger dryas period

abrupt increase in greenland snow accumulation at the end of the younger dryas event the warming at the end of the last glaciation was characterized by a series of abrupt returns to glacial climate the best known of which is the younger dryas event1 despite much study of the causes of this event and the mechanisms by which it ended many questions remain unresolved1 oxygen isotope data from greenland ice cores2 4 suggest that the younger dryas ended abruptly over a period of about 50 years dust concentrations2 4 in these cores show an even more rapid transition 20 years this extremely short timescale places severe constraints on the mechanisms underlying the transition but dust concentrations can reflect subtle changes in atmospheric circulation which need not be associated with a large change in climate here we present results from a new greenland ice core gisp2 showing that snow accumulation doubled rapidly from the younger dryas event to the subsequent preboreal interval possibly in one to three years we also find that the accumulation rate change from the oldest dryas to the bo11ing allerod warm period was large and abrupt the extreme rapidity of these changes in a variable that directly represents regional climate implies that the events at the end of the last glaciation may have been responses to some kind of threshold or trigger in the north atlantic climate system

near source attenuation of peak horizontal acceleration strong motion data recorded within 50 km of the rupture zone were used to study near source attenuation characteristics of horizontal peak ground acceleration for worldwide earthquakes of magnitudes 5 0 to 7 7 the data base consisted of 229 horizontal components of peak acceleration recorded from 27 earthquakes including the 15 october 1979 imperial valley earthquake these data were found to be adequately represented by the functional relationship pga a exp b m r c m d where pga represents the mean of the peak values scaled from the two horizontal components of each recording m is richter magnitude and r is distance from the fault rupture zone peak acceleration was found to be lognormally distributed with a standard error representing a 45 per cent increase in the median estimate the regression analysis statistically confirmed the results of earthquake simulation studies that have predicted peak acceleration to become independent of magnitude and distance in the near field an extensive sensitivity study showed that predictions based on our attenuation relationships are stable with respect to reasonable model and parameter variations an analysis of residuals was used to investigate the behavior of peak acceleration with respect to various earthquake site and recording parameters the more significant findings being 1 a similarity in the level of acceleration recorded on soil or rock 2 larger than average accelerations recorded at sites located on shallow soils or in areas of steep topography 3 larger than average accelerations associated with earthquakes having reverse fault mechanisms and 4 lower than average accelerations recorded in large embedded structures

high resolution multi 2d seismic imaging of solfatara crater campi flegrei caldera southern italy from active seismic data abstract a multi 2d imaging of the solfatara crater inside the campi flegrei caldera was obtained by the joint interpretation of geophysical evidences and the new active seismic dataset acquired during the ricen experiment eu project medsuv in 2014 we used a total of 17 894 first p wave arrival times manually picked on pre processed waveforms recorded along two 1d profiles criss crossing the inner solfatara crater and performed a tomographic inversion based on a multi scale strategy and a bayesian estimation of velocity parameters the resulting tomographic images provide evidence for a low velocity 500 1500 m s water saturated deeper layer at west near the outcropping evidence of the fangaia contrasted by a high velocity 2000 3200 m s layer correlated with a consolidated tephra deposit the transition velocity range 1500 2000 m s layer suggests a possible presence of a gas rich accumulation volume thanks to the mutual p wave velocity model we infer a detailed image for the gas migration path to the earth surface the gasses coming from the deep hydrothermal plume accumulate in the central and most depressed area of the solfatara being trapped by the meteoric water saturated layer therefore the gasses are transmitted through the buried fault toward the east part of the crater where the ring faults facilitate the release as confirmed by the fumaroles starting from the eastern surface evidence of the gas releasing in the bocca grande and bocca nuova fumaroles and the presence of the central deeper plume we suggest a fault situated in the central part of the crater which seems to represent the main buried conduit among them plays a key role

using rat gnawed seeds to independently date the arrival of pacific rats and humans in new zealand the pacific rat rattus exulans was transported throughout the south pacific with voyaging humans thus the earliest dated evidence of pacific rat can be used to infer first human contact until recently it was considered that rats arrived in new zealand with humans in the thirteenth century ad however controversial radiocarbon dates on pacific rat bones now suggest that rats reached the remote islands of new zealand with people c ad 50 150 these dates are anomalous because they imply human contact with new zealand more than 1000 years before any archaeological evidence for human presence and precede settlement of tropical eastern polynesia the ancestral homeland of maori the first new zealanders the early rat bone dates are controversial for other technical reasons which have been debated in the literature here distinctive rat gnawed seed cases preserved in sediments are used as a proxy to independently date the arrival of the pacific rat and humans in new zealand this method effectively b

a terrestrial palynological record for the last two glacial cycles from southwestern new zealand abstract a pollen profile from okarito pakihi bog in south westland new zealand extending from near present back to marine isotope stage mis 6 provides a continuous record of vegetation and climate change for the past two glacial cycles independent chronological control was obtained by ams radiocarbon dating of organic sediments in the upper part of the sequence and osl dating of inorganic silts in the lower part with a unique tie point provided by the ca 26 5 cal ka kawakawa tephra as was probably a common occurrence in this region the basin developed as a moraine dammed proglacial lake and remained lacustrine until the early holocene when a peat bog developed survival of the depositional site through subsequent multiple ice advances unusual in a glaciated landscape was probably assisted by lateral displacement of the basin relative to its source area across the alpine fault there is good correspondence between inferred periods of substantial treeline depression in the pollen profile and the record for ice advance in this region more cooling events are evident in the pollen record however presumably due to the fragmentary nature of glacial geomorphology the pollen record also shows broad consistency with the mis record and hence with the milankovitch orbital forcing model but with some departures including an early onset to the last glacial maximum lgm several sub milankovitch scale events are also evident including a mid lgm warming and lateglacial reversals during both the last and the penultimate deglaciation

variations in the frequency magnitude distribution with depth in two volcanic areas mount st helens washington and mt spurr alaska the frequency magnitude distribution of earthquakes characterized using the b value is examined as a function of space beneath mount st helens 1988 1996 and mt spurr 1991 1995 at mount st helens two volumes of anomalously high b b 1 3 can be observed at depths of 2 6 3 6 km below the crater floor and below 6 4 km these anomalies coincide with 1 the depth of vesiculation of ascending magma and 2 the suggested location of a magma chamber at mount st helens study of mt spurr reveals an area of high b value b 1 3 at a depth of about 2 3 4 5 km below the crater floor of the active vent crater peak we propose that the higher material heterogeneity in the vicinity of a magma chamber or conduit due to vesiculation of the ascending magma is the main cause of the increased b value at shallow depths alternatively interaction of magma with groundwater may have increased pore pressure and lowered the effective stress the deeper anomaly at mount st helens is likely caused by high thermal stress gradients in the vicinity of the magma chamber our results indicate that detailed mapping of the frequency magnitude distribution can be used as a tool to trace vesiculation and locate active magma chambers

last glacial jetting of cold waters through the subtropical convergence zone in the southwest pacific off eastern new zealand and some geological implications recent evidence suggests that the subtropical convergence stc zone east of new zealand shifted little from its modern position along chatham rise during the last glaciation and that offshore surface waters north of the stc zone cooled only slightly however at nearshore core site p69 2195 m depth 115 km off the east coast of north island and ca 300 km north of the modern stc zone planktonic foraminiferal species transfer function data and stable oxygen and carbon isotope records suggest that surface waters were colder by up to 6 c during the late last glacial period compared to the holocene and included a strong upwelling signature presently site p69 is bathed by south flowing subtropical waters in the east cape current the nearshore western end of chatham rise supports a major bathymetric depression the mernoo saddle through which some exchange between northern subtropical and southern subantarctic water presently occurs it is proposed that as a result of much intensified current flows south of the rise during the last glaciation a consequence of more compressed subantarctic water masses lowered sea level and an expanded and stronger westerly wind system there was accelerated leakage northwards of both australasian subantarctic water and upwelled antarctic intermediate water over mernoo saddle in a modified and intensified southland current the expanded cold water masses displaced the south flowing warm east cape current off southeastern north island and offshore divergence was accompanied by wind assisted upwelling of nutrient rich waters in the vicinity of p69 a comparable kind of inshore cold water jetting possibly characterised most glacial periods since the latest miocene and may account for the occasional occurrence of subantarctic marine fossils in onland late cenozoic deposits north of the stc zone rather than invoking wholesale major oscillations of the oceanic stc itself

late glacial and holocene vegetation and climatic history of the cass basin central south island new zealand abstract lithology pollen macrofossils and stable carbon isotopes from an intermontane basin bog site in southern new zealand provide a detailed late glacial and early holocene vegetation and climate record glacial retreat occurred before 17 000 cal yr b p and tundra like grassland shrubland occupied the basin shortly after between 16 500 and 14 600 cal yr b p a minor regional expansion of forest patches occurred in response to warming but the basin remained in shrubland forest retreated between 14 600 and 13 600 cal yr b p at about the time of the antarctic cold reversal at 13 600 cal yr b p a steady progression from shrubland to tall podocarp forest began as the climate ameliorated tall temperate podocarp trees replaced stress tolerant shrubs and trees between 12 800 and 11 300 cal yr b p indicating sustained warming during the younger dryas chronozone ydc stable isotopes suggest increasing atmospheric humidity from 11 800 to 9300 cal yr b p mild annual temperatures at least 1 c higher than present and moist conditions prevailed from 11 000 to 10 350 cal yr b p cooler more variable conditions followed and podocarp forest was completely replaced by montane nothofagus forest at around 7500 cal yr b p with the onset of the modern climate regime the cass basin late glacial climate record closely matches the antarctic ice core records and is in approximate antiphase with the north atlantic

quaternary deposits and landscape evolution in northeast southland new zealand abstract three kinds of quaternary sediments are present in northeast southland aeolian deposits terrace gravels and hill slope colluvium the aim of this paper is to review and describe the quaternary sediments and erosion pattern of northeast southland and reconstruct the likely climate under which sedimentation and erosion occurred aeolian deposition occurred intermittently from 250 000 yr b p but stratigraphic studies indicate widespread erosion of loess in the period 80 000 25 000 yr b p before a final period of loess accumulation in the late otiran 18o stage 2 terrace gravels are attributable to two sources a younger suite of three terraces is attributed to aggradation phases of the mataura river an older suite of three more weathered terraces is attributed to aggradation by a river flowing eastwards through the waimea plains from lumsden to gore the river is named the lumsden river at about 180 000 yr b p this river ceased flowing through the waimea plains colluvium on hill slopes is regionally stratified into two layers the lower deposits are identified as weathered sand and gravel sized colluvium derived from argillite and siltstone screes dated as being formed before 29 000 yr b p and attributed to 18o stage 4 the upper stonier deposits are attributed to 18o stage 2 the erosion and deposition pattern of aeolian deposits terrace gravels and slope colluvium cannot be explained by a temperature drop of c 5 c calculated for the last glacial period we conclude that on lowlands vegetation cover was periodically limited by extreme droughts and cold windy conditions causing erosion of previously deposited loess and encouraging scree formation on slopes during these periods the severe climate of northeast southland approximated to that of a cold desert

mapping active magma chambers by b values beneath the off ito volcano japan the b value of the frequency magnitude relation and thus the mean magnitude in the off ito volcanic area is not uniform based on detailed b value tomography using about 10 000 events in an area of 10 km radius and in the upper 15 km of the crust a high b value anomaly b 15 below 7 km depth and with a radius of about 2 km located below the coast southeast of ito contrasts with lower values of typically b 0 7 north of it and at shallower depths on the basis of surface deformations a tensile crack dislocation source was located above 7 km depth thus we surmise that the magma chamber in the off ito area was located below 7 km depth the correlation of a high b value anomaly with this model supports our hypothesis that active magma chambers may be mapped by high b value anomalies the magma body may be described as consisting of two parts a lower well established chamber below 11 km depth and a shallower part 11 7 km depth the b value in the volume surrounding the magma chamber increased from 0 7 during the 1980s to 1 5 during the earthquake swarms of the 1990s this may reflect a trend of increasing crack density due to the intrusion activity

rerewhakaaitu tephra a land sea marker for the last termination in new zealand with implications for global climate change abstract the rerewhakaaiutu tephra erupted from okataina volcanic centre north island new zealand at 14 700 95 14 c yr bp ca 17 600 cal yr bp at a time of rapid re organisation of earth s climate system at the end of the last glacial termination i it provides a distinctive isochron in a range of different environments in north island and in adjacent south pacific ocean sediments terrestrial evidence based on fluvial aggradation and downcutting relationships loess accumulation rates palaeovegetation patterns and buried soil development and mineralogy shows that marked amelioration of climate occurred shortly before the rerewhakaaitu tephra was deposited similarly marine evidence from around this time shows major changes in accumulation rates of sediment and aeolian quartz and in the abundance of various marine organisms while foraminiferal oxygen and carbon isotope records indicate that the arrival of the glacial meltwater signal occurred close to or just after the deposition of the rerewhakaaitu tephra these changes are discussed in relation to controls on climate by oceanic and atmospheric mechanisms the re organisation of climate commencing at ca 15 000 14 500 14 c yr bp ca 18 000 17 400 cal yr bp is detected elsewhere in the southern hemisphere and evidently was linked to orbitally forced warming which is thought to have initiated ice retreat in both hemispheres

source scaling and site effects at vesuvius volcano the site corrected source scaling pattern is estimated for local earthquakes 0 9 m d 3 6 at mt vesuvius the dataset comprises 35 low to moderate local earthquakes recorded by 14 three component seismic stations during 1993 1996 and 1999 site transfer functions in the frequency range 1 hz 25 hz are estimated from the spectra of s waves and coda waves and from the horizontal to vertical h v spectral ratios we applied the direct spectral ratios method to s waves considering as a reference the average spectrum and the inversion method to s waves and coda waves the site amplification on the coda waves was also compared with that evaluated using the wavelet transform the standard deviation associated with the experimental results is computed for all of the used methods results indicate a general agreement among the methods and the site transfer functions show interesting features the highest amplifications are found for frequencies lower than 12 hz for sites located at lower altitude the methods based on coda waves show highest amplification with respect to the methods based on s waves for most of the sites located in the summit part of the volcano this can be a phenomenon of coda localization which consists in the trapping inside the upper part of the volcano of scattered waves the h v spectral ratios do not show total agreement with the other methods mostly for the sites located in the summit part of the volcano the discrepancies among the results obtained in this work are also due to the different normalization applied in the methods of analysis generalized inversion method allowed us to estimate the source scaling of the site corrected source seismic spectrum for the investigated area the source scaling obtained in terms of seismic moment and source radii shows that the seismicity of mt vesuvius is characterized by stress drop as low as a few bars 10 bars except for the event of graphic 1 graphic 2 the scaling pattern shows an apparent linear relationship between source size and seismic moment for m d 3 3 but the statistical test shows that the linear trend has low reliability 1 embed inline graphic 1 gif 2 embed inline graphic 2 gif

pedogenesis by upbuilding in an extreme leaching and weathering environment and slow loess accretion south westland new zealand abstract soil formation is usually envisaged as acting from the surface downwards in many environments however the accumulation of sediment and soil formation are contemporaneous it is only where the rate of one process far exceeds the rate of the other that assumptions of topdown pedogenesis are appropriate the aspect of upbuilding pedogenesis that distinguishes it from topdown pedogenesis is that each increment of soil below the a horizon has experienced processes characteristic of all horizons above it this study examines the influence of upbuilding soil formation in a high rainfall environment of rapid soil formation and slow loess accretion an environment where upbuilding could have a noticeable influence on soil properties soils formed by topdown soil formation topdown soils are compared with soils formed in loess that accumulated from early last glaciation to the holocene upbuilding soils soils are compared in two environments alaquods on poorly drained terraces and placorthods or dystrochrepts on well drained moraine crests we have assumed that properties of the upbuilding soils inherited during the current topdown phase of pedogenesis beginning in the holocene are analogous to those in the topdown soils in this manner soil properties evolved during upbuilding are distinguished in well drained upbuilding soils on moraines subsoil organic carbon has mineralised so that profile trends are very similar to corresponding topdown soils upbuilding has enhanced weathering in subsoils which is reflected in lower ph lower total p and lower primary inorganic p than in topdown soil counterparts total p concentrations in upbuilding soils are much lower than unweathered loess and constant throughout the subsoil and there is almost no p in primary forms in contrast total p in c horizons of topdown soils reaches concentrations typical of the parent material and more than 30 of this is in a primary inorganic form the differences are attributed to each subsoil increment of upbuilding soils having been part of acid a and e horizons oxalate extractable fe and al data indicate that podzolisation was active during upbuilding poorly drained upbuilding soils on terraces have higher subsoil organic carbon inherited from former a or o horizons than comparable topdown soils buried a and o horizons inherited during upbuilding and preserved in the reducing conditions have acted as sinks for mobile al and now resemble podzolic illuvial bh horizons upbuilding through addition of loess to soils promotes a pedogenic pathway distinct from topdown pedogenesis consequently soil chronosequence studies that include soils on old loess mantled surfaces do not strictly satisfy the assumptions of soil chronosequences the nature and rate of soil processes inferred from these studies need revisiting the findings of this study are transferable to other environments where the rate of soil formation and sediment accumulation are comparable

estimation of response spectra and simulation of nonstationary earthquake ground motions abstract italian strong motion data were used to study the attenuation of response spectra and to simulate artificial accelerograms as a function of magnitude distance and site geology the database has already been utilized for the study of the atten uation of peak ground acceleration pga and velocity and consists of 95 accelero grams from 17 earthquakes of magnitudes ranging from 4 6 to 6 8 using multiple regressions we developed empirical predictive equations for the vertical and hori zontal components of response spectra corresponding to 14 frequencies ranging from 0 25 to 25 hz predictive equations aimed at the ground motion simulation were also estimated for time dependent frequency parameters strong ground motion du ration and arias intensity the shape of the predicted spectra is strongly dependent on magnitude and nearly independent of distance alluvium sites show an amplification effect with respect to stiff sites in different frequency ranges according to the thickness of the soil deposit the vertical horizontal spectral ratio in far field varies with magnitude and frequency from 0 35 to 0 85 the resulting response spectra are compared with the predictions of some recent attenuation relationships and with those proposed by the eurocode ec8 the simulation of nonstationary strong ground motions is achieved through an empirical method where time and frequency features of the motion are represented through the physical spectrum extending the spectral moments theory to the nonsta tionary case the simulated time histories fit the recorded accelerograms in terms of several ground motion amplitude measures such as peak acceleration peak velocity fourier spectra and response spectra the principal advantage of the proposed method consists in correlating the simulation parameters with earthquake magnitude source distance and soil conditions introduction in the field of seismic risk assessment the prediction of shaking intensity in future earthquakes plays a key role re liable estimates of the ground motions that structures must be designed to withstand are obtained mainly through em pirical predictive relationships developed after statistical analysis of data recorded during strong earthquakes many predictive equations are by now available in dif ferent regions of the world campbell 1985 1993 for the prediction of peak ground acceleration pga many fewer are the relationships developed for the prediction of response spectral values idriss 1991 boore

antarctic timing of surface water changes off chile and patagonian ice sheet response marine sediments from the chilean continental margin are used to infer millennial scale changes in southeast pacific surface ocean water properties and patagonian ice sheet extent since the last glacial period our data show a clear antarctic timing of sea surface temperature changes which appear systematically linked to meridional displacements in sea ice westerly winds and the circumpolar current system proxy data for ice sheet changes show a similar pattern as oceanographic variations offshore but reveal a variable glacier response time of up to 1000 years which may explain some of the current discrepancies among terrestrial records in southern south america

a 28 000 7600 cal yr bp pollen record of vegetation and climate change from pukaki crater northern new zealand a pollen record of vegetation and climate change representing the interval ca 28 000 7600 cal yr bp was obtained from a 52 5 m sediment core taken from a volcanic explosion crater at present sea level in auckland new zealand 36 59 s this provides one of the few continuous terrestrial records covering marine isotope stage 2 and part of stage 1 from the mid latitudes of the southern hemisphere chronology of the record is underpinned by eight distal taupo volcanic zone rhyolitic tephra of known age augmented by thirteen ams radiocarbon dates the last glacial maximum cooling extended from at least c 28 000 cal yr bp to ca 18 000 cal yr bp when vegetation apparently consisted of patches of beech dominated forest embedded within shrubland and grassland forest patches were probably larger or more widespread than those in central north island to the south but less extensive than further to the north in northland climate warming commenced ca 18 000 cal yr bp marked by the replacement of beech by conifers and angiosperms and by the expansion of forest at the expense of shrubland and grassland no clear late glacial climatic reversal is evident at this site early holocene forest is characterised by the replacement of the dominant forest tree prumnopitys taxifolia by dacrydium cupressinum following breach of the crater rim ca 7600 cal yr bp by rising sea level the maar was rapidly infilled with marine sediments over a period of ca 1000 years

a tentative chronology for the epica dome concordia ice core a tentative age scale edc1 for the last 45 kyr is established for the new 788 m epica dome c ice core using a simple ice flow model the age of volcanic eruptions the end of the younger dryas event and the estimated depth and age of elevated 10be about 41 kyr ago were used to calibrate the model parameters the uncertainty of edc1 is estimated to 10 yr for 0 to 700 yr bp up to 200 yr back to 10 kyr bp and up to 2 kyr back to 41 kyr bp the age of the air in the bubbles is calculated with a firn densification model in the holocene the air is about 2000 yr younger than the ice and about 5500 yr during the last glacial maximum

the role of egmont sourced tephra in evaluating the paleoclimatic correspondence between the bio and soil stratigraphic records of central taranaki new zealand abstract on the lower eastern flanks of egmont volcano western north island new zealand several egmont sourced tephras have been correlated to a radiocarbon dated peat site that provides a late last glacial to early post glacial record of vegetation and climate change in central taranaki the pollen spectra at this site indicates a mosaic of grassland shrubland and prumnopitys taxifolia dominant forest at ca 13 100 bp and suggests a climate cooler and drier than at present the ominance of tall podocarp forest by ca 12 900 bp suggests that climatic amelioration was rapid towards the end of the last glacial period initially this forest was dominated by prumnopitys taxifolia but at ca 11 000 bp was succeeded by dacrydium cupressinum indicating a steady shift to warmer and moister climate tephra interbedded with peat allows precise chrono correlation into the andisol forming environment the rapidity of climatic amelioration identified from variations in andisol morphology and mineralogy concurs with that indicated from pollen changes in the peat

the southern hemisphere westerlies in the australasian sector over the last glacial cycle a synthesis abstract the southern hemisphere westerlies in the southwest pacific are known to have waxed and waned numerous times during the last two glacial cycles though even semi continuous histories of the westerlies extend back no more than about 20 000 years we have good evidence for at least three scales of events a westerly maximum occurs at the last glacial maximum there is less conclusive evidence for another westerly maximum in the late holocene and for a minimum at ca 11 ka it is too early to ascribe even a cycle to these data but there are grounds to suggest that milankovitch precessional forcing may underlie the observed pattern there is also a quasi 2600 year cycle present in antarctic ice cores that appears to correlate to variation in westerly flow there is strong centennial scale variability in historical times the little ice age lia ca 1400 1850 was associated with a poleward shift in the circumpolar trough in the southern ocean strengthened westerly circulation over tasmania and a strengthening of southwesterly circulation and neoglaciation in southern new zealand while the preceding period 800 1400 ad was less certainly marked by reduced westerly flow from modern records we know that decadal and inter annual variability is important e g pacific decadal oscillation high latitude mode also known as the antarctic oscillation el nino southern oscillation only a minority of the proxies examined can identify changes on these temporal scales but data from tree rings ice cores and laminated lake sediments do indicate systematic changes in these phenomena through time rossby wave patterns are shown to play a critical role in long duration events as well as at the synoptic scale we conclude that westerly circulation is as strong now as at any time in the last glacial cycle in addition changes in latitudinal boundaries in the westerlies may be nearly as large in inter annual zonal shifts ca 2 maximum as in glaciation interglaciation movements ca 3 4 there is however reasonable evidence of strengthening weakening across much of the westerly belt at westerly maxima minima such as the lia early holocene

a cosmogenic nuclide chronology of the last glacial transition in north west nelson new zealand new insights in southern hemisphere climate forcing during the last deglaciation we present a new glacial chronology for the last glacial interglacial transition c 20 to 10 ka from the cobb valley nw nelson new zealand based on a suite of 10be and 26al cosmogenic exposure ages this chronology describes one of the most comprehensive deglaciation sequences from a late quaternary valley system in the southern hemisphere we chronicle the decay from the last local glacial maximum as follows onset of the last deglaciation that commenced no earlier than 18 19 ka followed by numerous short term still stands and or minor re advances over the ensuing 3 4 kyr and complete evacuation of ice by 14 ka we find no evidence to indicate a late glacial re advance commensurate with the northern hemisphere younger dryas chronozone the absence of a major glacial re advance in this valley during the latter stages of the last glacial interglacial transition lgit precludes a thermal decline in excess of about 3 c and suggests no decline the absence of late lgit re advances in the mountains of north west nelson while deglacial readvances occurred in the main ranges of the southern alps can be best explained if westerly wind forcing rather than large scale thermal decline is the primary control on glacier fluctuations at least during the deglaciation these findings challenge models of global climate change predicated on synchrony of millennial scale glacial transitions due to thermal changes between northern and southern hemispheres

regional insolation forcing of late quaternary climate change in the southern hemisphere southern new zealand positioned within the important southwesterly wind system is a prime site for examining interhemispheric linkages in climate change a series of cores drilled in the okarito pakihi peat bog now provides a continuous record of vegetation and climate change that may become a benchmark for the region the data include clear evidence for modification of the global climate change signal in the southern hemisphere by local variation in the intensity of solar radiation in agreement with the milankovitch orbital forcing hypothesis1 it is often assumed that glacial interglacial climate transitions occurred synchronously in the northern and southern hemispheres of the earth it is difficult to test this assumption because of the paucity of long continuous climate records from the southern hemisphere that have not been dated by tuning them to the presumed northern hemisphere signals2 here we present an independently dated terrestrial pollen record from a peat bog on south island new zealand to investigate global and local factors in southern hemisphere climate changes during the last two glacial interglacial cycles our record largely corroborates the milankovitch model of orbital forcing but also exhibits some differences in particular an earlier onset and longer duration of the last glacial maximum our results suggest that southern hemisphere insolation may have been responsible for these differences in timing our findings question the validity of applying orbital tuning to southern hemisphere records and suggest an alternative mechanism to the bipolar seesaw for generating interhemispheric asynchrony in climate change

statistical analysis of earthquake activity at etna volcano march 1981 eruption seismic activity that preceded accompanied and followed the 17 23 march 1981 etnean eruption has been statistically analyzed

thermoluminescence ages of post glacial loess rakaia river south island new zealand abstract we applied the partial bleach r beta thermoluminescence tl dating technique to two samples from massive post glacial loess overlying the last major aggradation gravel burnham formation near barrhill on the south bank of the rakaia river this site is roughly midway between the coast and the front range of canterbury previously the time of initiation of deposition of such loess in the region was only poorly constrained to somewhere between the interval 16 32 ka and ca 11 ka loess deposition has continued until today along margins of major braided rivers sample bhl 5 30 cm above the gravel gave a tl age of 11 7 1 9 1 ka and sample bhl 1 1 35 m above bhl 5 and 1 9 m below the surface gave an age of 5 49 0 70 ka thus age depth extrapolation at the barrhill site implies that loess deposition began at 13 2 ka and continued through the holocene to the present the average rate of deposition between the two tl samples was 0 22 0 07 mm year analytical error only and possibly greater thereafter the presence of the loess wedge dating from 13 2 ka indicates that the rakaia river began to entrench at about this time in this middle segment of the piedmont plain

fingerprints and age models for widespread new zealand tephra marker beds erupted since 30 000 years ago a framework for nz intimate abstract the role of tephras in the nz intimate project is a critical one because most high resolution palaeoclimatic records are linked and dated by one or more tephra layers in this review first we document eruptive distributional and compositional fingerprinting data both mineralogical and geochemical for 22 key marker tephras erupted since 30 000 years ago to facilitate their identification and correlation we include new glass compositional data the selected marker tephras comprise 10 from taupo and nine from okataina volcanoes rhyolitic one from tuhua volcano peralkaline rhyolitic and one each from tongariro and egmont volcanoes andesitic second we use four approaches to develop 2 age models for the tephras youngest to oldest 1 calendar ages for kaharoa and taupo y were obtained by wiggle matching log derived tree ring sequences dated by 14c 2 whakaipo v was dated using an age depth model from peat 3 14 tephras in the montane kaipo peat sequence waimihia s unit k whakatane tuhua mamaku rotoma opepe e poronui c karapiti b okupata konini waiohau rotorua rerewhakaaitu were dated by simultaneously wiggle matching stratigraphic position and 51 independent 14c age points against intcal04 using bayesian probability methods via both oxcal and bpeat and 4 the five oldest tephras erupted before ca 18 000 cal yr bp were dated by calibrating limited numbers of 14c ages using intcal04 okareka or comparison curves of the expanded cariaco basin sequence te rere kawakawa oruanui poihipi okaia kawakawa oruanui tephra the most widely distributed marker tephra was erupted probably ca 27 097 957 cal yr bp potential dating approaches for the older tephras include their identification in antarctic ice cores if present or annually laminated sediments for which robust calendar age models have been constructed high precision ams 14c dating on appropriate material from environmentally stable sites systematic luminescence dating or new radiometric techniques e g u th he if suitable minerals are available and errors markedly reduced further application of bayesian age modelling to stratigraphic sequences of 14c ages possibly augmented with luminescence ages may help refine age models for pre holocene tephras with the largest errors finally we discuss the critical role these marker tephras play in the ongoing construction of an event stratigraphy for the new zealand region which is a key objective of australasian and southern hemisphere intimate projects

direct marine terrestrial correlations wanganui basin new zealand the last 1 million years abstract wanganui basin a back arc basin in north island new zealand contains a detailed sequence of interfingering terrestrial and shallow marine sediments spanning the entire quaternary rhyolite tephras erupted from the taupo volcanic zone together with magnetostratigraphy and biostratigraphy facilitate correlations between wanganui basin and the astronomically calibrated oxygen isotope chronology of deep sea cores particularly over the last 1 ma eustatic changes are interpreted from both marine shelf sediments and marine terraces within the basin non marine sediments including loess dunesand and alluvial deposits coupled with pollen analyses are used to interpret climatic changes they can also be directly related to the marine record through stratigraphic relations between marine and non marine deposits in the basin

the taurewa eruptive episode evidence for climactic eruptions at ruapehu volcano new zealand the ca 10 500 years b p eruptions at ruapehu volcano deposited 0 2 0 3 km3 of tephra on the flanks of ruapehu and the surrounding ring plain and generated the only known pyroclastic flows from this volcano in the late quaternary evidence of the eruptions is recorded in the stratigraphy of the volcanic ring plain and cone where pyroclastic flow deposits and several lithologically similar tephra deposits are identified these deposits are grouped into the newly defined taurewa formation and two members okupata member tephra fall deposits and pourahu member pyroclastic flow deposits these eruptions identify a brief ca 2000 year but explosive period of volcanism at ruapehu which we define as the taurewa eruptive episode this episode represents the largest event within ruapehu s ca 22 500 year eruptive history and also marks its culmination in activity ca 10 000 years b p following this episode ruapehu volcano entered a ca 8000 year period of relative quiescence we propose that the episode began with the eruption of small volume pyroclastic flows triggered by a magma mingling event flows from this event travelled down valleys east and west of ruapehu onto the upper volcanic ring plain where their distal remnants are preserved the genesis of these deposits is inferred from the remanent magnetisation of pumice and lithic clasts we envisage contemporaneous eruption and emplacement of distal pumice rich tephras and proximal welded tuff deposits the potential for generation of pyroclastic flows during plinian eruptions at ruapehu has not been previously considered in hazard assessments at this volcano recognition of these events in the volcanological record is thus an important new factor in future risk assessments and mitigation of volcanic risk at tongariro volcanic centre

the late quaternary peat vegetation and climate history of the southern oceanic islands of new zealand abstract seven oceanic island groups chatham bounty snares antipodes auckland campbell and macquarie lie to the south and east of the southern new zealand mainland between the subtropical convergence and the antarctic convergence they are highly oceanic experiencing moist cool cloudy and windy climates deep peat soils cover most of the islands except for steep slopes and exposed high altitude sites the three large island groups chatham auckland and campbell support forest and tall scrub in the lowlands in the latter two grading with altitude through shrubland and grassland to upland tundra macrophyllous forbs create luxuriant herbfields in nutrient rich coastal sites and also as stunted forms dominate upland tundra associations the southernmost island macquarie has no woody species and is covered with tussock grassland herbfield and tundra vegetation cover is highly sensitive to soil saturation and exposure to the strong westerly winds of this region extensive oligotrophic bogs occur where drainage is poor and exposure high and forest and tall scrub are abundant only in sheltered well drained lowland sites glacial cirque levels indicate mean annual temperatures fell by 5 6 c during the last glacial maximum a depression of 6 10 c in sea surface temperatures is suggested by deep sea core analyses but this seems incompatible with terrestrial evidence auckland and campbell islands were extensively glaciated and grassland herbfield and tundra landscapes prevailed glaciers retreated by 15 000 yr bp and landscapes had stabilised and peat soils begun forming by 12 000 yr bp by the beginning of the holocene oligotrophic bog grassland and shrubland were dominant scrub and low forest spread slowly during the early holocene in the chatham auckland and campbell islands inhibited by cloudy moist climates low insolation and wet soils maximum extent of forest and scrub occurred between 6000 and 2000 yr bp most probably linked with a drying of the soils and increasing summer insolation upland sites and those exposed to westerly gales on auckland and campbell islands remained in grassland herbfield and bog throughout the holocene wind blown sand and stones in cliff edge peat profiles on auckland and campbell island from 8000 yr bp suggest strengthening westerly winds

asynchronous climate change between new zealand and the north atlantic during the last deglaciation climatic fluctuations recorded in antarctica and greenland during the last deglaciation 18 10 ka differ markedly in their timing it remains controversial whether local climate fluctuations recorded in southern mid latitudes relate primarily to northern or southern polar records we present multiproxy results from new zealand that show strong evidence for a minor cooling or slowdown in the rate of warming at the time of the north atlantic late glacial interstadial the younger dryas chronozone in new zealand was a period of resumed warming and increased westerly airflow differences between the hemispheres at this time were probably due to a reorganization of the thermohaline circulation system and associated changes in the meridional temperature gradient

reconstructing temperature during the last glacial maximum from lyndon stream south island new zealand using beetle fossils and maximum likelihood envelopes this paper presents fossil beetle data from a last glacial maximum site at the lyndon stream in the canterbury foothills south island new zealand paleotemperatures are derived using the maximum likelihood envelope mle model developed for regions where modern distribution data are incomplete marra et al 2004 late quaternary climate change in the awatere valley south island new zealand using a sine model with a maximum likelihood envelope on fossil beetle data quaternary science reviews 23 1637 1650 the mle model results indicate that summer temperatures in the canterbury foothills in close proximity to the major rakaia glacier at ca 22 000 c 14 yr bp were between 0 5 degrees c warmer and 1 9 degrees c cooler than present day in february summer mean minimum winter temperatures ranged between 1 degrees c warmer and 2 2 degrees c cooler than the present day these apparently surprising results confirm and quantify existing climate reconstructions from plant macrofossils from this site soons j m burrows c j 1978 dates for otiran deposits including plant microfossils and macrofossils from rakaia valley new zealand journal of geology and geophysics 21 607 615 they are consistent with new evidence of relatively mild conditions at least during some periods within the last glacial maximum chron in new zealand c 2006 elsevier ltd all rights reserved

the last glacial maximum lgm in western south island new zealand implications for the global lgm and mis 2 abstract the morainic and outwash deposits of the larrikins la and moana mn formations in north westland are correlated with the m5 t5 and m6 t6 deposits in south westland the la m5 deposits resulted from two separate otira glaciation glacial advances la 1 m5 1 la 2 m5 2 of essentially similar extents pollen sequences in peats and coverbeds extending from before to after the kawakawa tephra 26 500 cal yr bp indicate an extensive period of cold with a slight amelioration beginning shortly before tephra deposition this amelioration which is supported by interpretation of coverbed sequences in south westland separates the la 1 m5 1 and la 2 m5 2 advances the three westland glacial advances la 1 m5 1 la 2 m5 2 and mn m6 culminated at ca 28 000 21 500 and 19 000 cal yr bp the last being followed by major rapid glacier retreat pollen and caco 3 records from dsdp 594 east of the south island reflect contemporary glacier fluctuations on the east side of the southern alps they show the last major cold period as lasting from ca 34 000 to ca 16 000 years ago a period starting before the culmination of the la 1 m5 1 advance and ending later than the beginning of glacier retreat from the mn m6 advance the period from the la 1 m5 1 culmination to the mn m6 culmination represents the lgm in new zealand a slightly longer lgm is recorded in chile and a long lgm may also be indicated in australia a long lgm in the southern hemisphere is supported by the global sea level curve and by the regional antarctic temperature criteria of the vostok ice core these different records indicate a southern hemisphere lgm beginning at least as early as 27 000 years ago much earlier than the ocean last isotope maximum lim from 21 500 to 18 000 years ago the beginning of mis 2 defined primarily from deep sea benthic 18 o at 24 000 years is well after the beginning of ice advances leading to the southern hemisphere lgm a review of global land and ocean correlations is desirable

volcano meteorological tsunamis thec ad 200 taupo eruption new zealand and the possibility of a global tsunami meteorological tsunamis are long period waves that result from meteorologically driven disturbances they are also generated by phase coupling with atmospheric gravity waves arising through powerful volcanic activity the ad 1883 krakatau eruption generated volcano meteorological tsunamis that were recorded globally because of its extreme violence and energy release 150 50 megatons explosive yield and by analogy with the krakatau event it is highly possible that the ignimbrite emplacement phase of the c ad 200 taupo eruption of north island new zealand generated a similar volcano meteorological tsunami that may have reached coastal areas worldwide tsunami deposits of identical age to the taupo eruption occur in central coastal new zealand and probably relate to that event definitive evidence elsewhere has not yet been found in theory volcano meteorological tsunamis are likely to be produced during comparable eruptive events at other explosive volcanoes and thus represent an additional volcan

palaeo climate reconstruction from stable isotope variations in speleothems a review abstract speleothems are now regarded as valuable archives of climatic conditions on the continents offering a number of advantages relative to other continental climate proxy recorders such as lake sediments and peat cores they are ideal materials for precise u series dating yielding ages in calendar years thereby circumventing the radiocarbon calibration problems associated with most other continental records stable isotope studies in speleothems have shifted away from attempting to provide palaeo temperature reconstructions to the attainable goal of providing precise estimates for the timing and duration of major o isotope defined climatic events characterised by high signal to noise ratios e g glacial interglacial transitions dansgaard oeschger oscillations the 8200 year event unlike the marine records speleothem data sets are not tuned and their independent chronology offers opportunities to critically assess leads and lags in the climate system that in turn can provide important insights into forcing and feedback mechanisms improved procedures for the extraction and measurement of stable isotope ratios in fluid inclusions trapped in speleothems are likely to provide in the near future a much enhanced basis for the quantitative interpretation of o isotope ratios in speleothem calcite the latter developments open up once again the tantalising prospect of palaeo temperature estimates but more importantly perhaps provide a direct test for a new generation of general circulation models whose hydrological cycles will incorporate the water isotopes the literature is reviewed briefly to provide for the reader a sense of the current state of the art and to provide some pointers for future research directions

glacial interglacial control of terrigenous and biogenic fluxes in the deep ocean off a high input collisional margin a 139 kyr record from new zealand abstract sediment input to the deep ocean off the new zealand collisional plate boundary is large and variable as revealed by a 139 kyr old record from the 34 92 m long core md97 2121 mass accumulation rates mars were derived for terrigenous and biogenic carbonate and silica sedimentary components with temporal control from a stable isotope age model verified by tephra and radiocarbon ages terrigenous mars changed in phase with glacio eustatic fluctuations of sea level highest rates 30 g cm 2 kyr coincided with the late regressive lowstand early transgressive phase of marine isotope stage mis 2 when rivers discharged at or near the shelf edge lesser but still high terrigenous rates 20 30 g cm 2 kyr characterized peak warm phases of early mis 5 and 1 when a strengthened subtropical inflow probably introduced sediment from fluvial and seabed sources to the north of md97 2121 however during prolonged highstands the flux declined as more sediment was retained on a tectonically subsiding shelf with a shore parallel current paradoxically the lowest mars 10 5 g cm 2 kyr occurred in mis 4 either sea level was too high to allow much sediment to escape off shelf or the fluvial input was modest or both these factors despite the terrigenous dominance biogenic mars are high and are 2 4 times larger than sw pacific ocean rates mars were lowest during mis 4 and 3 possibly due to reduced marine production under a lowered input of fluvial micronutrients in contrast mars increased irregularly though glacial maxima to peak at 5 6 g cm 2 kyr carbonate and 2 2 5 g cm 2 kyr silica in early mid mis 5 and 1 such rates reflected the interaction of macronutrient rich subantarctic waters sourced from the south with local micronutrient rich subtropical waters production also responded to warmer temperatures elevated nutrient runoff and a more stratified surface ocean later in mis 5 and 1 fluxes reduced as less productive subtropical waters prevailed that biogenic and aeolian mar profiles are out of phase suggests fe fertilization by aerosolic dust was not a major influence

from induced seismicity to direct time dependent seismic hazard the growing installation of industrial facilities for subsurface exploration worldwide requires continuous re nements in understanding both the mechanisms by which seismicity is induced by eld operations and the related seismic hazard particularly in proximity of densely populated areas induced low to moderate magnitude seismicity characterized by high frequency content can be clearly felt by the surrounding inhabitants and in some cases may produce damage in this respect we propose a technique for time dependent probabilistic seismic hazard analysis to be used in geothermal elds as a monitoring tool for the e ects of on going eld operations the technique integrates the observed features of the seismic ity induced by uid injection and extraction with a local ground motion prediction equation the result of the analysis is the time evolving probability of exceedance of peak ground acceleration which can be compared with selected critical values to manage eld operations to evaluate the reliability of the proposed technique we applied it to data collected in the geysers geothermal eld in northern california between 1 september 2007 and 15 november 2010 we show that in the period considered the seismic hazard at the geysers was variable in time and space which is a consequence of the eld operations and the variation of both seismicity rate and b value we conclude that for the exposure period taken into account i e 2 months as a conservative limit peak ground acceleration values corresponding to the lowest probability of exceedance e g 30 must not be exceeded to ensure safe eld operations we suggest testing the proposed technique at other geothermal areas or in regions where seismicity is induced for example by hydrocarbon exploitation or carbon dioxide storage

bergstroemograptus n gen crawfordi harris from the ordovician of western newfoundland specimens of cardiograptus crawfordi harris from the middle table head formation on port au port peninsula display a partially monopleural arrangement of the two thecal series this feature and the rhabdosome size and shape make c crawfordi so different from the genotype of cardiograptus that it can no longer be retained in that genus the port au port specimens are identical to isolated specimens from the middle table head formation at daniel s harbour previously identified as skiagraptus sp especially with regard to the partially monopleural construction however australian specimens of the genotype of skiagraptus probably have a dipleural arrangement thus the newfoundland specimens cannot be assigned to that genus the proximal end development of c crawfordi is very different from that of apoglossograptus and kalpinograptus the other graptolites with partially monopleural arrangements therefore a new genus here named bergstroemograptus is defined for it bergstroemograptus represents an ind

possible enso signals prior to the last glacial maximum during the last deglaciation and the early holocene from new zealand annually laminated lake sediments from a maar crater in auckland new zealand were analyzed spectrally for three time slices just prior to the last glacial maximum lgm during the deglaciation and during the early holocene strong spectral power in 2 7 year 9 30 year and a centennial 80 120 year timescale prior to the lgm and during two brief intervals in the deglaciation contrasts with virtually no spectral power during the rest of the deglaciation and during the early holocene the antarctic cold reversal acr appears to be the younger deglacial event the results indicate that el nino southern oscillation enso and possibly the inter decadal pacific oscillation ipo operated in a modern mode prior to the lgm pulsed on and off during the deglaciation and were suppressed or absent from northern new zealand during the early holocene the acr was a period of enhanced southwesterly flow over northern new zealand

test of ams 14c dating of pollen concentrates using tephrochronology previous attempts to radiocarbon date sediments 10 kyr from the high rainfall region of westland new zealand a critical location for investigation of interhemispheric patterns of climate change have been problematic this study building on recent work by vandergoes and prior 2003 shows that ams 14c dating of pollen concentrates has potential to provide more reliable ages than other sediment constituents including plant macrofossils the method was applied to sediments from three sites containing the 22 6k 14c yr kawakawa tephra which provided an independent test of the 14c ages although some minor laboratory contamination was detected in tests on background standards the modelled relationship between sample mass and measured 14c content permitted an appropriate correction to be determined improved pollen concentrations derived by density separation between 1 4 and 1 2 specific gravity and sieving in the range 10 50 m provided either older ages than other fractions of the same sample or where in situ contamination was not evident equivalent ages differences in degree of in situ contamination between depositional environments indicated that in westland lake sites may be less susceptible to contamination by younger carbon than peat sites where this process may be facilitated by root penetration into underlying sediments copyright 2006 john wiley sons ltd

chronology of palaeoclimatic change at the end of the last glaciation analysis of sediments recorded in a piston core located east of southern north island new zealand gives a detailed record of climate change at the end of the last glacial accumulation rates1 of both detrital quartz and biological carbonate and biogenic silica components of the sediment are much higher during glacial than post glacial time and they all show a synchronous rapid decline at 14 700 yr bp we attribute this to a decline in intensity of the strong glacial westerly winds in the new zealand region as the polar winds contracted to their present latitudes2 6 the greatest rate of quartz accumulation occurs between 16 200 and 14 700 yr bp and is not matched by any change in carbonate or silica accumulation we believe this reflects accelerated fluvial transport of detritus out of the mountain ranges and consequently increased aeolian dust transport before the decline of the polar westerlies

a new 27 ky high resolution east antarctic climate record the ice core recently drilled at the dome concordia site on the east antarctic plateau provides a new high resolution isotope record covering part of the last glacial the last transition and the holocene the two step shape of the deglaciation is remarkably similar for all the ice cores now available on the east antarctic plateau the first warming trend ends about 14000 years ago and is followed by the well marked antarctic cold reversal acr with a secondary peak common to all records during the deglaciation there are more similarities between the near coastal site of taylor dome and inland east antarctica than between taylor dome and central greenland however the results for epica do appear to confirm the taylor dome timescale after about 14 ka showing cooling into the acr roughly in phase between greenland and antarctica while the overall deglacial pattern is asynchronous this suggests that the now classical picture of a temperature seesaw between antarctica and greenland may be too simplistic

merging active and passive data sets in traveltime tomography the case study of campi flegrei caldera southern italy we propose a strategy for merging both active and passive data sets in linearized tomographic inversion we illustrate this in the reconstruction of 3d images of a complex volcanic structure the campi flegrei caldera located in the vicinity of the city of naples southern italy the caldera is occasionally the site of significant unrests characterized by large ground uplifts and seismicity the p and s velocity models of the caldera structure are obtained by a tomographic inversion based on travel times recorded during two distinct experiments the first data set is composed of 606 earthquakes recorded in 1984 and the second set is composed of recordings for 1528 shots produced during the serapis experiment in 2001 the tomographic inversion is performed using an improved method based on an accurate finite difference traveltime computation and a simultaneous inversion of both velocity models and earthquake locations in order to determine the adequate inversion parameters and relative data weighting factors we perform massive synthetic simulations allowing one to merge the two types of data optimally the proper merging provides high resolution velocity models which allow one to reliably retrieve velocity anomalies over a large part of the tomography area the obtained images confirm the presence of a high p velocity ring in the southern part of the bay of pozzuoli and extends its trace inland as compared to previous results this annular anomaly represents the buried trace of the rim of the campi flegrei caldera its shape at 1 5 km depth is in good agreement with the location of hydrothermalized lava inferred by gravimetric data modelling the vp vs model confirms the presence of two characteristic features at about 1 km depth a very high vp vs anomaly is observed below the town of pozzuoli and is interpreted as due to the presence of rocks that contain fluids in the liquid phase a low vp vs body extending at about 3 4 km depth below a large part of the caldera is interpreted as the top of formations that are enriched in gas under supercritical conditions

oxygen isotope and palaeotemperature records from six greenland ice core stations camp century dye 3 grip gisp2 renland and northgrip oxygen isotope variations spanning the last glacial cycle and the holocene derived from ice core records for six sites in greenland camp century dye 3 grip gisp2 renland and northgrip show strong similarities this suggests that the dominant influence on oxygen isotope variations reflected in the ice sheet records was regional climatic change differences in detail between the records probably reflect the effects of basal deformation in the ice as well as geographical gradients in atmospheric isotope ratios palaeotemperature estimates have been obtained from the records using three approaches i inferences based on the measured relationship between mean annual 18o of snow and of mean annual surface temperature over greenland ii modelled inversion of the borehole temperature profile constrained either by the dated isotopic profile or iii by using monte carlo simulation techniques the third of these approaches was adopted to reconstruct holocene temperature variations for the dye 3 and grip temperature profiles which yields remarkably compatible results a new record of holocene isotope variations obtained from the northgrip ice core matches the grip short term isotope record and also shows similar long term trends to the dye 3 and grip inverted temperature data the northgrip isotope record reflects i a generally stronger isotopic signal than is found in the grip record ii several short lived temperature fluctuations during the first 1500 yr of the holocene iii a marked cold event at ca 8 2 ka the 8 2 ka event iv optimum temperatures for the holocene between ca 8 6 and 4 3 ka a signal that is 0 6 stronger than for the grip profile v a clear signal for the little ice age and vi a clear signal of climate warming during the last century these data suggest that the northgrip stable isotope record responded in a sensitive manner to temperature fluctuations during the holocene copyright 2001 john wiley sons ltd

14c activity and global carbon cycle changes over the past 50 000 years a series of 14c measurements in ocean drilling program cores from the tropical cariaco basin which have been correlated to the annual layer counted chronology for the greenland ice sheet project 2 gisp2 ice core provides a high resolution calibration of the radiocarbon time scale back to 50 000 years before the present independent radiometric dating of events correlated to gisp2 suggests that the calibration is accurate reconstructed 14c activities varied substantially during the last glacial period including sharp peaks synchronous with the laschamp and mono lake geomagnetic field intensity minimal and cosmogenic nuclide peaks in ice cores and marine sediments simulations with a geochemical box model suggest that much of the variability can be explained by geomagnetically modulated changes in 14c production rate together with plausible changes in deep ocean ventilation and the global carbon cycle during glaciation

comparison of oxygen isotope records from the gisp2 and grip greenland ice cores recent results1 2 from the greenland ice core project grip summit ice core suggest that the climate in greenland has been remarkably stable during the holocene but was extremely unstable for the time period represented by the rest of the core spanning the last two glaciations and the intervening eemian inter glacial here we present the complete oxygen isotope record for the greenland ice sheet project 2 gisp2 core drilled 28 km west of the grip core we observe large rapid climate fluctuations throughout the last glacial period which closely match those reported for the grip core however in the bottom 10 of the cores spanning the eemian interglacial and the previous glacia tion there are significant differences between the two records it is possible that ice flow may have altered the chronological sequences of the stratigraphy for the bottom part of one or both of the cores considerable further work will be necessary to evaluate the likelihood of this and the extent to which it will still be possible to extract meaningful climate information from the lowest sections of the cores

tephras and new zealand archaeology establishing an accurate date for earliest polynesian settlement in new zealand is essential for understanding patterns of settlement and associated enviromental impacts and the processes and rates of cultural change in eastern polynesia tephra deposits from five volcanic centres together with exotic sea rafted pumice provide isochronous constraints on the timing of earliest settlement and human impacts in northern new zealand a local basaltic tephra from rangitoto island auckland and locally distributed andesitic tephras from egmont volcano directly date human occupation toc ad 1400 1450 distal andesitic tephras tufa trig formation from mt ruapehu tongariro volcanic centre help constrain the timing of earliest anthropogenic deforestation signals in hawke s bay sea rafted loisels pumice s although of uncertain stratigraphic reliability in places overlies cultural remains that can be no younger thanc ad 1350 along the east coast north island the regionally extensive rhyolitic kaharoa tephra which erupted from okataina volcano between c ad 1300 1390 is the critical settlement layer datum for dating prehistory in the north island no human artefacts are recorded beneath it and the earliest inferred environmental impacts by humans are dated to c ad 1280 just prior to its deposition this maximum date matches the earliest radiocarbon dates derived for both settlement and human impacts from archaeological and natural sites c ad 1250 and implies that the onset of deforestation was essentially contemporaneous with initial settlement the widespread rhyolitic taupo tephra which erupted from taupo volcanoc ad 200 provides an isochronous benchmark well before earliest settlement the tephra may coincide approximately with a putative earlier transient contact in new zealand based on pacific rat bone rattus exulans dates more precise calendrical dates on the tephras via dendrochronology or ice core records or other dating methods would help refine assessment of the timing of earliest settlement while extending the distributional range of critical tephra layers through application of crypto tephra analysis could lead to a greater understanding of settlement patterns

ground motion prediction equations for the geysers geothermal area based on induced seismicity records abstract the geysers geothermal field in northern california which has been actively exploited since the 1960s is the world s largest geothermal field the continuous injection of fluids and the consequent stress perturbations induce seismicity that is clearly felt in the surrounding communities in order to evaluate seismic hazard due to induced seismicity and the effects of seismicity rate level on the population and buildings in the area reliable ground motion prediction equations gmpes must be developed this paper introduces the first gmpes specific for the geysers area in terms of peak ground velocity pgv peak ground acceleration pga and 5 damped spectral acceleration sa t at t 0 2 s 0 5 s and 1 0 s the adopted non linear mixed effect regression technique to derive the gmpe includes both fixed and random effects and it permits to account for both inter event and intra event dependencies in the data site specific effects are also estimated from the data and are corrected in the final ground motion model we used data from earthquakes recorded at 29 stations of the berkeley geysers network during the period september 2007 through november 2010 the magnitude range is 1 3 m w 3 3 whereas the hypocentral distances range between 0 5 km and 20 km the comparison of our new gmpe for the geysers with a standard model derived in a different tectonic context shows that our model is more robust when predictions have to be made for induced earthquakes in this geothermal area

distal record of multi sourced tephra in onepoto basin auckland new zealand implications for volcanic chronology frequency and hazards we have documented 80 tephra beds dating from ca 9 5 to 50 ka contained within continuously deposited palaeolake sediments from onepoto basin a volcanic explosion crater in auckland new zealand the known sources for distal 190 km from vent tephra include the rhyolitic taupo volcanic centre 4 and okataina volcanic centre 14 and the andesitic taranaki volcano 40 and tongariro volcanic centre 3 the record provides evidence for four new events between ca 50 and 28 ka mangaone subgroup suggesting okataina was more active than previously known the tephra record also greatly extends the known northern dispersal of other mangaone subgroup tephra ten rhyolitic tephra pre date the rotoehu eruption ca 50 ka and some are chemically dissimilar to post 50 ka rhyolites some of these older tephra were produced by large magnitude events however their source remains uncertain eight tephra from the local basaltic auckland volcanic field avf are also identified interpolation of sedimentation rates allow us to estimate the timing of 12 major explosive eruptions from taranaki volcano in the 27 5 9 5 ka period in addition 28 older events are recognised the tephra are trachytic to rhyolitic in composition all have high k2o contents 3 wt and there are no temporal trends this contrasts with the proximal lava record that shows a trend of increasing k2o with time by combining the onepoto tephra record with that of the previously documented pukaki crater 15 avf basaltic fall events are constrained at 34 6 30 9 29 6 29 6 25 7 25 2 24 2 23 8 19 4 19 4 15 8 and 14 5 ka and three pre 50 ka events this provides some of the best age constraints for the avf and the only reliable data for hazard recurrence calculations the minimum event frequency of both distal and local fall events can be estimated and demonstrates the auckland city region is frequently impacted by ash fall from many volcanoes

environmental processes of the ice age land oceans glaciers epilog knowledge of the state of the earth at the last glacial maximum lgm an interval around 21 000 years ago is an important benchmark for understanding the sensitivity of global environmental systems to change much progress in understanding climates of the lgm has occurred in the 20 years since the end of the climap project of the 1970s climate long range investigation mapping and prediction here we review this progress based on presentations and discussion at a rst open science meeting of the epilog project environmental processes of the ice age land oceans glaciers held in delmenhorst germany may 1999 we outline key controversies and document protocols for epilog contributions so that a new synthesis of the lgm earth can emerge as an open project of the world s community of scientists 2001 elsevier science ltd all rights reserved

temperature change is the major driver of late glacial and holocene glacier fluctuations in new zealand advance and retreat of temperate glaciers is largely controlled by changes in temperature and precipitation but the relative importance of these drivers is debated numerical modeling of a new zealand glacier reveals that temperature is the dominant control on glacier length we find that a glacial advance dated to ca 13 000 yr b p requires a cooling event of 3 4 c this mid latitude southern hemisphere cooling is similar in magnitude to the antarctic cold reversal in the vostok ice core record and likely to be a response to the same climate signal

response of surface water masses and circulation to late quaternary climate change east of new zealand a series of cores from east of new zealand have been examined to determine the paleoceanographic history of the late quaternary in the sw pacific using planktonic foraminiferal data distinct shifts of species can be seen between glacial and interglacial times especially south of chatham rise east of south island foraminiferal fragmentation ratios and benthic planktonic foraminiferal ratios both show increased dissolution during glacials especially isotope stage 2 to the south of chatham rise the present day subtropical convergence appears to be tied to the chatham rise at 44 s but during glacial times this rise separated cold water to the south from much warmer water to the north with an associated strong thermal gradient across the rise we estimate that this gradient could have presented as much as an 8 c temperature change across 4 of latitude during the maximum of the last ice age there is only weak evidence of the younger dryas cool event but there is a clear climatic optimum between 8 and 6 4 ka with temperatures 1 2 c higher than the present day the marine changes compare well with vegetational changes on both south and north island

climate of the last glaciation in new zealand based on aerosolic quartz influx in an andesitic terrain abstract on western north island new zealand a record of climatic change during the last glaciation is preserved in a terrestrial coverbed sequence of dominantly andesitic provenance here a succession of five loess like andisol units postdates the global high sea level stand of oxygen isotope substage 5e

probabilistic seismic hazard at mt etna italy the contribution of local fault activity in mid term assessment abstract in this work we tackle the problem of seismic hazard at etna deriving from the recurrent seismogenic activity of local faults by adopting two independent methods based on probabilistic approaches we assess the hazard in terms of macroseismic intensity and represent the occurrence probability calculated for different exposure times both on maps and at fault scale seismic hazard maps obtained by applying the site approach through the sasha code and a new probabilistic attenuation model indicate the eastern flank of the volcano as the most hazardous with expected intensity i exp in 50 years i e the standard exposure time adopted in the seismic regulations ranging from degrees ix to x ems in shorter exposure periods 20 10 5 years values of i exp up to ix are also reached in the same area but they are clearly determined by the earthquakes generated by the timpe fault system in order to quantify the contribution of local seismogenic sources to the hazard of the region we reconstruct the seismic history of each fault and calculate with sasha the probability that earthquakes of a given intensity may be generated in different exposure times results confirm the high level of hazard due to the s tecla moscarello and fiandaca faults especially for earthquakes of moderate intensity i e vi i 0 vii with probabilities respectively exceeding 50 and 20 in 10 years and 30 and 10 in 5 years occurrence probability of major events i 0 viii at the fault scale has also been investigated by statistics on intertimes under stationary assumptions we obtain a probability of 6 8 in 5 years for each structure by introducing the time dependency time elapsed since the last event occurred on each fault through a bpt model we identify the moscarello and s tecla faults as the most probable sources to be activated in the next 5 years 2013 2017 this result may represent a useful indication to establish priority criteria for actions aimed at reducing seismic risk at a local scale

timing of the late glacial climate reversal in the southern hemisphere using high resolution radiocarbon chronology for kaipo bog new zealand abstract the pattern of climate change in the southern hemisphere during the younger dryas yd chronozone provides essential constraint on mechanisms of abrupt climate change only if accurate high precision chronologies are obtained a climate reversal reported previously at kaipo bog new zealand had been dated between 13 600 and 12 600 cal yr b p and appeared to asynchronously overlap the yd chron but the chronology based on conventionally radiocarbon dated bulk sediment samples left the precise timing questionable we report a new high resolution ams 14 c chronology for the kaipo record that confirms the original chronology and provides further evidence for a mid latitude southern ocean cooling event dated between 13 800 and 12 400 cal yr b p 2 range roughly equivalent to the antarctic cold reversal