object oriented classification of a high spatial resolution spot5 image for mapping geology and landforms of active volcanoes semeru case study indonesia the present work explores the object oriented classification ooc of high spatial resolution hsr satellite panchromatic imagery for mapping the geology of the persistently active semeru volcano and its ring plain east java indonesia a panchromatic spot5 image and a digital elevation model dem have been used to identify geologic units structures landforms and deposits the panchromatic image was georeferenced and enhanced using histogram equalization the enhanced image was segmented into polygons using the envifx exelis software the polygons were delineated and classified on the basis of spectral panchromatic hues and textures topographic slope elevation information and geologic geomorphic processes the validity of classification was evaluated by interpreting google earth images aerial photographs and limited field observations the classification consists of three hierarchical levels across the volcanic area of about 745 km2 the first operational spatial level includes seven large volcano domains based on the spectral content of the volcanic tectonic and lithological structures and principal catchments the second operational level based on contextual relationships topography drainage network vegetation cover type stratigraphy and slope dynamics encompasses 20 geological units that range between 30 and 80 km2 in area among the units the third operational level distinguishes as many as 47 geomorphological sub units 0 25 25 km2 according to slope gradient deposit type mass wasting process and weathering the resulting map provides a detailed pattern of geologic and geomorphic features unlike previous geologic maps that identified only 11 stratigraphic units we show that the high spatial resolution panchromatic spot5 scene can help to safely map the geology and landforms of persistently active volcanoes such as semeru we have applied the ooc technique on one hsr geoeye panchromatic image to map another active volcano merapi in central java after considerable geomorphic changes due to the large eruption in 2010

palaeo moisture evolution in monsoonal central asia during the last 50 000 years abstract the late quaternary climate history of monsoonal central asia was inferred from 75 palaeoclimatic records which provide information about moisture conditions in the last 50 ka or part of this period wet conditions occurred during middle and late marine isotope stage 3 while the last glacial maximum lgm was characterized by dry climate conditions in the region a stepwise climate amelioration is suggested by the climate records following the lgm several climate signals of this period which were reported from high latitude ice core records are preserved in archives from monsoonal central asia as well during the early holocene high effective moisture was inferred from most records from the area dominated by the indian monsoon e g the tibetan plateau suggesting that holocene optimal climate conditions occurred there during this period in contrast areas which are dominated by the south east asian monsoon se monsoon and the westerlies in north western and north central china mongolia do not uniformly show an early holocene climate optimum for this area optimal conditions prevailed during the mid holocene these apparent contradictions can possibly be explained by the regional uplift and descent of air masses in the holocene during the early holocene strengthened insolation possibly caused an enhanced low level convergence over the tibetan plateau which led to the intensification of the summer monsoon the strong air uplift caused intensified precipitation and air divergence in the upper troposphere over the tibetan plateau the areas adjacent to the north therefore experienced an intensified descent of air masses and consequently increased aridity the majority of the palaeoclimatic records suggest reduced effective moisture since the late holocene in the region

volume estimation of the 1998 flank collapse at casita volcano nicaragua a comparison of photogrammetric and conventional techniques in october 1998 a precipitation triggered flank collapse occurred at casita volcano nicaragua leading to a devastating lahar in this paper the failure volume was calculated using a range of methods several pre and post failure digital elevation models dems were created based on photogrammetric cartometric and surveying data the wide range in resulting volumes prompted an assessment of the accuracies and potential problems associated with each of the datasets and techniques used the best estimate for the failure volume is 1 6 106 m3 it is based on a vegetation corrected pre failure dem generated using automated digital photogrammetry and a post failure surface based on a field survey carried out with a total station the volume figure is approximately an order of magnitude higher than values reported in previous publications all of which are based solely on field estimates this demonstrates that values reported in the literature if they are not based on rigorous quantitative analysis must be regarded with caution copyright 2002 john wiley sons ltd

predicting equilibrium scour hole geometry near angled stream deflectors using a three dimensional numerical flow model stream rehabilitation projects often involve the installation of instream structures such as flow deflectors the objective of this study is to use the output of a three dimensional numerically simulated flow field over a flat predeformation bed to predict the planform extent of the equilibrium scour hole near stream deflectors of varying angles it is shown that the upstream extent of the simulated flow separation zone determines the upstream limit of scour whereas the lateral scour extent at the nose of the deflector is determined by the width of the separation zone further scour depths are greatest in regions where strong downwelling negative vertical velocity exists and the position of the local minimum dynamic pressure point in the simulated flow field defines the downstream limit of scouring the results have implications for future design of habitat improvement structures where different angles and lengths of structures could potentially be tested prior to their implementation to determine the resultant scour geometry

insolation values for the climate of the last 10 million years new values for the astronomical parameters of the earth s orbit and rotation eccentricity obliquity and precession are proposed for paleoclimatic research related to the late miocene the pliocene and the quaternary they have been obtained from a numerical solution of the lagrangian system of the planetary point masses and from an analytical solution of the poisson equations of the earth moon system the analytical expansion allows the direct determination of the main frequencies with their phase and amplitude numerical and analytical comparisons with the former astronomical solution ber78 are performed so that the accuracy and the interval of time over which the new solution is valid can be estimated the corresponding insolation values have also been computed this analysis leads to the conclusion that the new values are expected to be reliable over the last 5 ma in the time domain and at least over the last 10 ma in the frequency domain

characteristics of late quaternary monsoonal glaciation on the tibetan plateau and in east asia abstract glaciers fed by monsoonal precipitation are mainly located on the tibetan plateau and easternmost asia these are characterized by simultaneous accumulation and ablation in summer season the southeast part of the tibetan plateau experiences monsoonal precipitation in excess of 1000 mm yr resulting in maritime temperate glaciers in contrast precipitation in the middle and northwest part of the tibet plateau decreases from 1000 to 200 mm yr resulting in the formation of continental cold glaciers during the last glacial the regions of heavy monsoonal precipitation were restricted to the southeast corner of the plateau the westerly weak precipitation zone shifted southward and occupied the major northwest part of the plateau where the extreme continental type glaciers greatly expanded in the eastern margin of asia including taiwan central japan hokkaido and probably mount changbai maritime type glaciers were more extensive because of higher monsoonal precipitation especially heavy snowfall in northwest japan owing to the rich moisture content of the winter monsoon over the japan sea the millennial scale monsoon intensity and glacial cycle in the tibetan plateau are strongly affected by the precession cycle and the orbit inclination cycle which dominate the solar irradiance variation in low latitudes as the high radiation and strong monsoon caused the warmer and wetter climate during 40 30 ka the low radiation produced a weak monsoon and large depression of temperature and precipitation around 21 ka this climatic pattern differs from that in the high latitudes where the eccentricity cycle is prominent the temperature during the last glacial maximum lgm was 6 9 c lower than today on the tibetan plateau and the equilibrium line altitude was depressed by about 1000 m in the southeast part and in the east south and west margins of the plateau where precipitation was high the equilibrium line depression was 500 300 m in the inner and especially the west part of the plateau this variation in equilibrium lines might be caused by the combined effect of the decrease in precipitation the expansion of extreme continental glaciers and the active uplift of glaciated mountains the estimation of a glaciated area of about 350 000 km2 in the tibetan plateau and roughly 500 000 km2 in high asia based on observations of prominent features of lgm glacier extension may be the direct evidence that shows there was no quaternary unified ice sheet developed in the tibetan plateau

application of synthetic aperture radar sar imagery to volcano mapping in the humid tropics a case study in east java indonesia volcanoes in humid tropical environments are frequently cloud covered typically densely vegetated and rapidly eroded these factors complicate field and laboratory studies and even the basic identification of potentially active volcanoes numerous previous studies have highlighted the potential value of radar remote sensing for volcanology in equatorial regions here cloud and vegetation penetrating lhh band 24 cm synthetic aperture radar sar data from the japanese earth resources satellite jers 1 are used to investigate persistently active volcanoes and prehistoric calderas in east java indonesia the lhh band jers 1 sar produces high spatial resolution 18 m imagery with relatively high incidence angle that highlights structures and topographic variations at or greater than the wavelength scale while minimising geometrical distortions such as layover and foreshortening these images along with internet browse data derived from the canadian radarsat mission provide new evidence relating regional tectonics to volcanism throughout east java volcanic events such as caldera collapse at the tengger caldera appear to have been partly controlled by northwest aligned faults related to intra arc sedimentary basins similar regional controls appear important at historically active lamongan volcano which is encircled by numerous flank maars and cinder cones a previously undocumented pyroclastic sheet and debris avalanche deposit from the jambangan caldera complex is also manifested in the synoptic radar images at the currently active semeru volcano these data permit identification of recent pyroclastic flow and lahar deposits radar data therefore offer a valuable tool for mapping and hazard assessment at late quaternary volcanoes the criteria developed in the analysis here could be applied to other regions in the humid tropics

reconstruction of the 2 4 million km2 late pleistocene ice sheet on the tibetan plateau and its impact on the global climate during 20 expeditions new data were obtained on the maximum extent of glaciation in tibet and the surrounding mountains evidence was found of moraines at altitudes as low as 460 m on the southern flank of the himalayas and 2300 m on the northern slope of the tibetan plateau in the qilian shan on the northern slopes of the karakorum aghil and kuen lun moraines occurred as far down as 1900 m in southern tibet radiographic analyses of erratics document former ice thicknesses of at least 1200 m glacial polishing and knobs in the himalayas and karakorum are proof of glaciers as thick as 1200 2000 m on the basis of this evidence a 1100 1600 m lower equilibrium ela line was reconstructed for the ice age which would mean 2 2 4 million km2 of ice covering almost all of tibet since the equilibrium ela line was far below the average altitude of tibet on mount everest and k2 radiation was measured up to 6650 m yielding values of 1200 1300 w m2 because of the subtropical latitude and the high altitude solar radiation in tibet is 3 4 times greater than the energy intercepted between 60 and 70 n or s with an area of 2 2 4 million km2 and an albedo of 90 the tibetan ice sheet caused the same heat loss on the earth as a 6 9 6 million km2 sized ice sheet at 60 70 n because of its proximity to the present day equilibrium ela line tibet must have undergone large scale glaciation earlier than other areas being subject to intensive radiation the tibetan ice must have performed an amplifying function during the onset of the ice age

teleconnections between the subtropical monsoons and high latitude climates during the last deglaciation the major deglacial intensification of the southwest monsoon occurred at 11 450 150 calendar years before present synchronous with a major climate transition as recorded in greenland ice an earlier event of monsoon intensification at 16 000 150 calendar years before present occurred at the end of heinrich layer 1 in the atlantic and parallels the initial rise in global atmospheric methane concentrations and the first abrupt climate changes in the antarctic thus the evolution of the monsoonal and high latitude climates show teleconnections but hemispheric asymmetries superimposed on abrupt events the monsoonal climate shows high frequency variability of 1785 1450 and 1150 year oscillations and abrupt climate change seems to occur when at least two of these oscillations are in phase

deformation of stromboli volcano italy during the 2007 eruption revealed by radar interferometry numerical modelling and structural geological field data abstract the activity of stromboli volcano is characterized by very low energy explosions occurring every 10 15 min throwing out lava above the crater rim during 2007 the volcano showed an anomalous activity in which new effusive vents developed 27 february and 9 march and a major explosion took place on 15 march this paper presents an integrated study based on a structural geological field survey interferometric radar monitoring and numerical modelling on the deformations of the upper nw flank of the volcano sciara del fuoco sdf the field survey carried out during the 2007 events shows the development of mainly ne striking fissures and fractures on the northern part of the upper sdf in january 2007 the ground based synthetic aperture radar gb insar installed on the flank of the sdf showed a progressive acceleration of movement on the ne crater preceding the eruption of 27 february 2007 by the first half of february the acceleration also involved the upper portion of the sdf and on 27 february the eruption started with the opening of new vents and deformation rates higher than the measurement capability of the radar device on 8 9 march 2007 the gb insar highlighted the formation of a bulge on the nw sector of the sdf preceding the opening of an additional vent to understand the deformation pattern recorded during the eruption a numerical simulation was carried out by using the flac 3d code based on the integration of all the data the deformations observed in the pre effusive phase before 27 february seem to be related to the intrusion of a sw ne striking dyke the bulging recorded before the 9 march vent opening is instead to be associated with the intrusion of a sub horizontal sill

ground based insar reveals conduit pressurization pulses at stromboli volcano at stromboli volcano southern italy only few minor precursors gas output have been identified for major strombolian explosions we use ground based interferometric synthetic aperture radar gbinsar technology to monitor the displacement rate of the summit area of stromboli we analysed the 2009 2011 period the analysis of the displacement rate has been performed by dividing the summit zone monitored by the gbinsar into three regions corresponding to the edge of the crater area 1 and 2 and to the slope of the ne crater 3 pulses of rapid expansion of sector 3 of variable duration and amplitude appear in coincidence with periods of intense activity that include lava flows and major explosions we associate this expansion with the pressurization of the magma column that is recharged by deep derived gas promoting the onset of major explosion dominated activity

in flow evolution of lahar deposits from video imagery with implications for post event deposit interpretation mount semeru indonesia abstract the hazardous and unpredictable nature of lahars makes them challenging to study yet the in flow processes characterizing these events are important to understand as a result much of the previous research on lahar sedimentation and flow processes has been derived from experimental flows or stratigraphic surveys of post event deposits by comparison little is known on the time dependent sediment and flow dynamics of lahars in natural environments using video footage of seven lahars on the flanks of semeru volcano east java indonesia the present study offers new insights on the in flow evolution of sediment in natural lahars video analysis revealed several distinctive patterns of sediment entrainment and deposition that varied with time related fluctuations in flow these patterns were used to generate a conceptual framework describing possible processes of formation for subsurface architectural features identified in an earlier lateral survey of lahar deposits on semeru volcano gomez and lavigne 2010a the formation of lateral discontinuities was related to the partial erosion of transitional bank deposits followed by fresh deposition along the erosional contact this pattern was observed over the course of several lahar events and within individual flows observations similarly offer potential explanations for the formation of lenticular features depending on flow characteristics these features appeared to form by preferential erosion or deposition around large stationary blocks and by deposition along channel banks during episodes of channel migration or channel constriction finally conditions conducive to the deposition of fine laminated beds were observed during periods of attenuating and surging flow these results emphasize the difficulties associated with identifying process structure relationships solely from post event deposit interpretation and illustrate that an improved understanding of the time dependent sediment dynamics in lahars may be advantageous when interpreting post event structural features

high resolution evidence from southern china of an early holocene optimum and a mid holocene dry event during the past 18 000 years abstract computer models suggest that the holocene optimum for east asian summer monsoon precipitation occurred at different times in different regions of china previous studies indicate that this time transgressive holocene optimum should have been experienced about 3000 yr ago in southern china in this study we describe a section which allows us to test this timing directly we have closely examined high resolution eutrophic peat mud sequences covering the past 18 000 cal yr at dahu jiangxi on the southern boundary of the mid subtropical zone in china late pleistocene successions in the dahu record indicate cooler and much wetter conditions relative to synchronous events in north central china our results indicate that the holocene optimum occurred between ca 10 000 and 6000 cal yr ago in southern china consistent with the global pattern conditions were relatively dry and cold from 6000 to 4000 cal yr ago our data also support the conclusion that the last deglaciation to early holocene in the south was much wetter resulting in the formation of dense broad leaved forests which could have acted to moderate land temperature 10 000 to 6000 cal yr ago yielding a stable early holocene climate after 6000 cal yr forest reduction led to unstable land temperatures and possibly to a northerly shift of the subtropical high pressure system whatever the mechanism these changes resulted in decreased precipitation between 6000 and 4000 cal yr b p in southern china

geology tectonics and the 2002 2003 eruption of the semeru volcano indonesia interpreted from high spatial resolution satellite imagery abstract the paper illustrates the application of high spatial resolution satellite images in interpreting volcanic structures and eruption impacts in the tengger semeru massif in east java indonesia we use high spatial resolution images ikonos and spot 5 and aerial photos in order to analyze the structures of semeru volcano and map the deposits geological and tectonic mapping is based on two dems and on the interpretation of aerial photos and four spot and ikonos optical satellite images acquired between 1996 and 2002 we also compared two thermal surface kinetic temperature aster images before and after the 2002 2003 eruption in order to delineate and evaluate the impacts of the pyroclastic density currents semeru s principal structural features are probably due to the tectonic setting of the volcano a structural map of the tengger semeru massif shows four groups of faults orientated n40 n160 n75 and n105 to n140 conspicuous structures such as the se trending horseshoe shaped scar on semeru s summit cone coincide with the n160 trending faults the direction of minor scars on the east flank parallels the first and second groups of faults the semeru composite cone hosts the currently active jonggring seloko vent this is located on and buttressed against the mahameru edifice at the head of a large scar that may reflect a failure plane at shallow depth dipping 35 towards the se this failure plane may correspond to a weak basal layer of weathered volcaniclastic rocks of tertiary age we suggest that the deformation pattern of semeru and its large scar may be induced by flank spreading over the weak basal layer of the volcano it is therefore necessary to consider the potential for flank and summit collapse in the future the last major eruption took place in december 2002 january 2003 and involved emplacement of block and ash flows we have used the 2003 aster surface kinetic temperature image to map the 2002 2003 pyroclastic density current deposits we have also compared two 10 m pixel images acquired before and after the event to describe the extent and impact of an estimated volume of 5 45 106 m3 of block and ash flow deposits an ash rich pyroclastic surge escaped from one of the valley confined block and ash flows at 5 to 8 km distance from the crater and swept across the forest and tilled land on the sw side of the bang river valley downvalley the temperature of the pyroclastic surge decreased and a mud rich deposit coated the banks of the bang river valley thus hazard mitigation at semeru should combine 1 continuous monitoring of the eruptive activity through an early warning system and 2 continuous remote sensing of the morphological changes in the drainage system due to the impact of frequent pyroclastic density currents and lahars

magnetic susceptibility evidence of monsoon variation on the loess plateau of central china during the last 130 000 years the magnetic susceptibility of loess and paleosols in central china represents a proxy climate index closely related to past changes of precipitation and vegetation and thus to summer monsoon intensity time series of magnetic susceptibility constructed for three loess paleosol sequences in the southern part of the chinese loess plateau document the history of summer monsoon variation during the last 130 000 yr they correlate closely with the oxygen isotope record of stages 1 to 5 in deep sea sediments soils were forming during intervals of strong summer monsoon whereas loess units were deposited at times of reduced monsoon intensity the chinese loess paleosol sequence can thus be viewed as a proxy record of asian monsoon variability extending over the last 2 5 myr

tracing the evolution of 2010 merapi volcanic deposits indonesia based on object oriented classification and analysis of multi temporal very high resolution images abstract we compare identification delineation and recording of freshly erupted deposits around active volcanoes from very high resolution optical images with that done by traditional geologic mapping object oriented classification ooc and normalized difference spectral indices of vegetation moisture and soil redness ndvi ndwi and ndrsi have been applied to sub metric geoeye 1 and pleiades images to identify and map pyroclastic and lahar deposits and trace their spatio temporal evolution over two years following the 2010 eruption of merapi volcano indonesia we could identify several categories of pyroclastic depositional areas and also map the damaged forest and destroyed cultivated terraces and settlements in the gendol and opak river basins on the south flank of the volcano more than 75 of erupted deposits were delineated semi automatically unlike the ground geological map based on photo interpretation of the 2010 geoeye image and field observations a temporal image analysis using bivariate scatter diagrams of the three spectral indices between 2010 and 2012 and a combination of ndwi and ndvi separated areas affected by surges from unscathed vegetation use of ndrsi and ndwi allowed us to differentiate overbank pyroclastic density current deposits from wet lahar deposits ndrsi values close to 0 refer to scoria rich pyroclastic deposits about 40 of the devastated upper catchment was recolonized by vegetation between 2010 and 2012 the recovery also took place in the forested valley margins affected by ash cloud surges the morphometric analysis of the initial drainage network digitized from the 2011 2012 images demonstrated 1 the resurfacing of pristine 2010 pdc deposits by runoff and 2 incision or remobilization by lahars it took two years following the eruption in the rugged upper catchment devastated by high energy surges to fully develop the hydrographic network it is however still rudimentary on gently sloping fans created by overbank pdc deposits in the middle valley thus suggesting the importance of slope gradient grain size permeability and thickness of deposits as much as 35 of the 2010 pdc deposits emplaced in the vicinity of the river channels were remobilized by lahars over the two post eruption rainy seasons and also by constant mining activities studies on the erosion of the pyroclastic deposits after 2012 need to concentrate on the upper reach of the catchment on the south flank

the threat of hazards in the semeru volcano region ineast java indonesia abstract semeru volcano 3676 m the highest volcano in java is one of the most active volcanoes in indonesia its activity has occurred almost continuously since 1967 the activity is manifested by mostly strombolian type eruptions with lava extrusions which extend into a lava tongue in kobokan breach southeast slope of the volcano the lava tongue is unstable after reaching a certain volume the tongue collapses and causes pyroclastic flows to the southeast direction traveling a maximum of about 11 km downslope the collapse is sometimes triggered by volcanic eruptions the main dangers are not due to eruption and collapse of the lava tongue but caused by the secondary dangers the secondary dangers are more destructive and distributed over a wider area tens of kilometres from the source the natural hazards in the semeru region are not only related to volcanic activity which is so called lahar but also non volcanic processes such as debris flow this phenomenon is related to the heavy rainfall which causes landslides in the altered volcanic deposit areas the flow of the mixture of water and landslide materials has devastated large areas the occurrences of the secondary flow is unpredictable and its viscosity is much lower than lahar this flow is distributed over a wide area and threatens cultivated land and densely populated and developing urban areas

surface height adjustments in pyroclastic flow deposits observed at unzen volcano by jers 1 sar interferometry abstract pyroclastic flows from the 1990 1995 eruption of unzen a dacitic volcano in the southwest of japan descended the mountain along a variety of routes causing widespread damage and loss of life interferograms constructed from jers 1 l band synthetic aperture radar sar images show a number of features related to these pyroclastic flows and their secondary effects the most useful interferogram in this respect is based on images acquired on 22 july 1993 and 1 december 1993 and shows the descent paths for pyroclastic flows occurring in four valley systems within this time window as zones of decorrelation caused by the repeated resurfacing the 22 july 1993 sar image was through considerable good fortune acquired only 2 6 days after a major pyroclastic flow had descended into the mizunashi valley so that in the absence of rainfall the fresh 2 m thick deposits were dry when first imaged the largest differential surface height changes observed in the interferogram represent height decreases in the vertical of 12 cm and significantly lie within a small region of the mizunashi valley which was resurfaced by the pyroclastic flow of 19 july 1993 but not subsequently within this small region radar coherence is higher maximum correlation value of 0 75 in a center valley site where ash but relatively few large boulders are present in a qualitative sense the new ash surfaces exhibit higher levels of radar coherence than the older pre 19 july deposits in other unzen valleys visited by pyroclastic flows smaller differential surface height decreases 4 cm are observed where the surface deposits were emplaced by events taking place between 1 3 months before the acquisition date of the 22 july 1993 image the extra 8 cm of surface height decrease observed in the case of the freshly laid mizunashi deposits must result from a deflationary mechanism or mechanisms operating in a spatially uniform manner in order for radar coherence to be maintained a number of possible causative mechanisms including hydroconsolidation initiated by the seepage of rainwater into a newly deposited ash sheet deflation on gas release basal erosion settlement and substrate relaxation are discussed here given the relatively low emplacement temperatures of the unzen ash 300 500 c it is unlikely that viscous deformation within the body of the fresh ash deposits is responsible for the subsidence comparison of the 22 july 1993 1 december 1993 interferogram with a landsat 4 thematic mapper image of unzen acquired on 10 january 1994 highlights a ribbon like zone of radar decorrelation running along the course of the mizunashi valley which marks the path of debris flows that occurred within the time interval between the two sar images used in the construction of the interferogram overall these results demonstrate the utility of interferometric sar derived surface height and coherence measurements for monitoring the pyroclastic and debris flow regimes of active volcanoes

a lateglacial and holocene lake record from the nianbaoyeze mountains and inferences of lake glacier and climate evolution on the eastern tibetan plateau abstract our 12 81 m long record from lake ximencuo provides insight into the lateglacial and holocene evolution of the lake and the nianbaoyeze glacier in its catchment and the regional climate history since 19 kyr lake ximencuo was a permanent deep lake throughout its history in contrast to numerous lakes on the tibetan plateau which experienced shallow lake levels or even desiccation during the lateglacial lake ximencuo was fed by large quantities of meltwater in the lateglacial the existence of glaciated upper catchment areas is apparently a prerequisite for lakes on the tibetan plateau which maintained relatively high water levels during the generally cold and dry periods following the global lgm 21 kyr a minor re advance of the nianbaoyeze glacier was recorded coeval with the greenland stadial 2a 16 4 and 14 5 kyr followed by rapid warming apparently synchronous with the greenland interstadial 1 warmest conditions were recorded at lake ximencuo during the early holocene which was punctured by a remarkable pulse of climate deterioration around 8 3 kyr this spell represents probably the 8 2 kyr event of the north atlantic region suggesting that it had a significant impact on the tibetan plateau colder conditions of longer duration occurred from 4 7 to 3 7 kyr apparently in phase with numerous records signalling colder and drier conditions on the tibetan plateau two minor spells of colder conditions and probably catchment erosion were recorded in the late holocene between 2 0 and 1 4 kyr and between 0 5 and 0 1 kyr with the latter representing the little ice age it is unclear whether human activities may have accelerated or even solely triggered the late holocene erosion events

evaluation of geophysical mass flow models using the 2006 block and ash flows of merapi volcano java indonesia towards a short term hazard assessment tool abstract the dynamics and depositional processes associated with block and ash flows bafs are most commonly inferred to be a function of granular or inertial grain flow similar to debris flows and cold rock avalanches existing geophysical mass flow models are either based on frictional mohr coulomb behavior the titan2d model developed at the state university of new york at buffalo usa or another rheological law i e a constant retarding stress eventually adding some viscous and turbulent components the volcflow model developed at the laboratoire magmas et volcans clermont ferrand france the 2006 bafs of merapi present a rare opportunity to test these two well established models against a well constrained field example integration of high resolution field based data into numerical simulations allows the validity of these models to be tested and rapid quantification of best fit input parameters we first show that with the incorporation of spatially varying bed friction angles titan2d is capable of reproducing the paths runout distances areas covered and deposited volumes of the 2006 merapi flows over highly complex topography however some discrepancies with field data are noted and the velocity and travel time of the flows do not match entirely using a single free parameter a constant retarding stress simulations obtained with the volcflow model also reproduce the morphology and distribution of the natural deposits as well as the time of emplacement and velocities of the flows the results suggest that the performance of these models in simulating actual events is critically dependent on 1 the calibration of the model by using extensive field based data such as deposit distribution and processes of flow generation transport and deposition 2 the incorporation of a suitable numerical topographic dataset i e high resolution digital elevation model and 3 the choice of input parameters such as location and volume of the initial pile of material and source characteristics single or multiple dome collapse dome collapse duration and total volume of collapsed material sensitivity analyses and inundation maps based on the probability of impact were used to produce a suite of potentially inundated areas from future gravitational dome collapse events affecting the gendol valley and adjacent areas on the southern flank of the volcano our results provide the basis for defining hazard zonations of key areas at risk from bafs which will be generated during future comparable eruptions at merapi

lignin biomarker and isotopic records of paleovegetation and climate changes from lake erhai southwest china since 18 5kabp abstract a sound knowledge of paleovegetation is fundamental to better understanding of past climate variability and provides necessary background for improving predictions of future climate changes in the present study stable isotopes 13c and 15n and lignin biomarker of sedimentary organic matter som from lake erhai 25 50 n 100 10 e southwest china were determined to reconstruct paleovegetation and to find vegetation climate relationships the stable carbon isotope signatures suggested that the organic matter mostly derived from c3 plants throughout the depositional periods since 18 5 ka bp the variability of isotopic values of carbon 13c 28 8 to 23 9 and nitrogen 15n 1 2 4 1 might be related to changes in terrestrial runoff i e precipitation compositions of the alkaline cuo oxidation products of lignin showed a significant change in terrestrial vegetation from gymnosperm rich to angiosperm rich plants at lake catchments in the early holocene the lignin phenol vegetation index lpvi also indicated changes in terrestrial vegetation with few more subtle changes during the last 18 5 ka as a single proxy of entire characteristic of terrestrial vegetation in comparison to past asian monsoon records 18o record in stalagmite of dongge cave lpvi suggested a direct linkage between vegetation changes and asian monsoon variability that might be influenced by global climate changes

the holocene history and development of the tonle sap cambodia abstract the tonle sap the great lake of central cambodia is the central component of wetland ecosystems in the lower mekong river basin and is of enormous conservation value the lake s unusual hydraulic relationship with the mekong river and its consequent sensitivity to monsoon variability makes the tonle sap sensitive to climate change exploring the dynamics and development of this system under different climate regimes of the past offers a perspective on possible future impacts which is critical for sound management biostratigraphic and sedimentological data derived from cores of lake sediment indicate that during the period 7000 to ca 5500 14 c years before present the lake was less variable than present in terms of depth during the annual cycle of flood and may have been strongly influenced by saline tidal waters associated with higher than present seas levels as regional environments became drier and more seasonal in the late holocene more sediment was re suspended during the increasingly marked dry season lake level minimum lowering the effective sediment accumulation rate contrary to current interpretations of the history of the lake and associated wetland ecosystems the data presented here imply that regional hydraulic connections between the lake and the mekong river existed from at least the early holocene

paleoclimate of southwestern china for the past 50 000 yr inferred from lake sediment records abstract long sediment cores 12 5 and 13 5 m from two lakes in yunnan province were used to infer the paleoclimate of southwest china over the past 50 000 yr during the holocene and marine isotope stage mis 3 bio induced carbonate precipitation and organic matter om production was high suggesting warm temperatures and high primary productivity in contrast sediment inorganic carbon ic and organic carbon oc concentrations were low in last glacial deposits from 38 000 to 12 000 cal yr b p indicating cool temperatures and low productivity the 50 000 yr record has alternating peaks of carbonate and coarse grain 38 m quartz that reflect warm moist interglacial or interstadial conditions alternating with cold dry glacial or stadial conditions respectively spectral analysis of the carbonate and quartz signals reveals power concentrated at periods of 7200 and 8900 cal yr respectively that may reflect a nonlinear climate response to precessional forcing at a time of reduced eccentricity modulation mcintyre and molfino 1996 oxygen isotope values of calcite from yunnan lake cores indicate the summer monsoon was weak during the last glaciation from 50 000 to 12 000 cal yr b p the summer monsoon intensified between 12 000 and 8000 cal yr b p but weakened gradually in response to insolation forcing during the mid to late holocene our results support the overpeck et al 1996 model that posits a weak summer monsoon during the last glaciation that responded nonlinearly to insolation forcing when its intensity was affected by eurasian snow cover and ice sheet extent the summer monsoon intensified and responded linearly to seasonal insolation forcing in the holocene when ice volume diminished

a new greenland ice core chronology for the last glacial termination 1 we present a new common stratigraphic timescale for the north greenland ice core project ngrip and grip ice cores the timescale covers the period 7 9 14 8 kyr before present and includes the bolling allerod younger dryas and early holocene periods we use a combination of new and previously published data the most prominent being new high resolution continuous flow analysis cfa impurity records from the ngrip ice core several investigators have identified and counted annual layers using a multiparameter approach and the maximum counting error is estimated to be up to 2 in the holocene part and about 3 for the older parts these counting error estimates reflect the number of annual layers that were hard to interpret but not a possible bias in the set of rules used for annual layer identification as the grip and ngrip ice cores are not optimal for annual layer counting in the middle and late holocene the timescale is tied to a prominent volcanic event inside the 8 2 kyr cold event recently dated in the dye 3 ice core to 8236 years before a d 2000 b2k with a maximum counting error of 47 years the new timescale dates the younger dryas preboreal transition to 11 703 b2k which is 100 150 years older than according to the present grip and ngrip timescales the age of the transition matches the gisp2 timescale within a few years but viewed over the entire 7 9 14 8 kyr section there are significant differences between the new timescale and the gisp2 timescale the transition from the glacial into the bolling interstadial is dated to 14 692 b2k the presented timescale is a part of a new greenland ice core chronology common to the dye 3 grip and ngrip ice cores named the greenland ice core chronology 2005 gicc05 the annual layer thicknesses are observed to be log normally distributed with good approximation and compared to the early holocene the mean accumulation rates in the younger dryas and bolling periods are found to be 47 2 and 88 2 respectively

late holocene sedimentary and environmental development of the northern mekong river delta vietnam abstract a sedimentological and palynological study of three sediment cores from the northern mekong river delta shows the regional sedimentary and environmental development since the mid holocene sea level highstand a sub to intertidal flat deposit of mid holocene age is recorded in the northernmost core shoreline deposits in all three cores show descending ages from n to s documenting 1 the early stages of the late holocene regression and 2 the subsequent delta progradation the delta plain successions vary from floodplain deposits with swamp like elements to natural levee sediments the uppermost sediments in all cores show human disturbance to varying degrees the most intense alteration is recorded in the northernmost core where the palynological signal together with a charcoal peak indicates the profound change of the environment during the modern land reclamation the sediments from at least one of the three presented cores do not show a true delta facies succession but rather estuary like features as also observed in records from southern cambodia this absence is probably due to lack of accommodation space during the initial phase of rapid delta progradation which impeded the development of true delta successions as shown in cores from the southern mekong river delta

new insights on late quaternary asian palaeomonsoon variability and the timing of the last glacial maximum in southwestern china abstract a 6 35 m core 06sd was retrieved from lake shudu yunnan province china the sediments spanning the period 22 6 10 5 kcal yr bp 6 35 1 44 m were analysed using a combination of variables including pollen charcoal particle size magnetic susceptibility and loss on ignition the resulting palaeorecord provides a high resolution reconstruction of late pleistocene to early holocene climatic and environmental changes in southwestern china our findings indicate that from c 22 6 to 17 7 kcal yr bp vegetation assemblages were primarily aligned to sparse xerophytic grassland tundra or cold tolerant boreal pinus forest indicating that climatic conditions in southwestern china were cold and dry however from c 17 7 to 17 4 kcal yr bp the lake shudu record is punctuated by marked environmental changes these include the establishment of denser vegetation cover a marked expansion of boreal pinus forest and enhanced hydrological activity in the catchment over centennial timescales perhaps suggesting that stepwise variations in the asian monsoon were triggering fundamental environmental changes over sub millennial timescales thereafter the pollen record captures a period of environmental instability reflected in fluctuations across all of the variables which persists until c 17 1 kcal yr bp after c 17 1 kcal yr bp the expansion of steppe vegetation cover and cold cool mixed forest consisting of mesophilous vegetation such as tsuga and picea thermophilous trees including ulmus and deciduous quercus inferred from the lake shudu pollen record point to the establishment of warmer wetter and perhaps more seasonal conditions associated with a strengthening asian summer monsoon during the shift from pleistocene to holocene climatic conditions

the 2006 pyroclastic deposits of merapi volcano java indonesia high spatial resolution ikonos images and complementary ground based observations abstract on 16 june 2006 an overpass of ikonos coincided with the emplacement of an active block and ash flow fed by a lava dome collapse at merapi volcano java indonesia it was the first moving pyroclastic flow recorded on a satellite image the very high spatial resolution of the image indicated the extent and impact of pyroclastic material that was deposited during and prior to the day of image acquisition a number of features associated with the hazardous block and ash flows emplaced in narrow deep gorges were mapped interpreted and analysed the high spatial resolution ikonos imagery worked extremely well for identifying pyroclastic deposits the block and ash flow and surge deposits recognized in the ikonos images include 1 several channel confined flow lobes and tongues in the box shaped gorge 2 thin ash cloud surge deposit and knocked down trees in constricted areas on both slopes of the gorge 3 fan like overbank deposits on the gendol tlogo interfluves from which flows were re routed in the tlogo minor valley 4 massive overbank flow lobes on the right bank of the gendol river which destroyed the village of kaliadem 0 5 km from the main channel a small part of this flow was re channelled into the opak tributary valley the high resolution ikonos images also helped us to identify geomorphic obstacles that enabled flows to ramp up and spill out from the sinuous channel as flow avulsion flow avulsions are dangerous as the redirect flows to unexpected areas away from the main channel valley fills from previous deposits channel bends and anthropogenic barriers in the channel locally known as sabo dams influence the down valley passage of the flows sabo dams originally built to ameliorate the effect of high sediment load streams caused block and ash flows to avulse of the containing channel and devastate populated areas

volcanic hazards at mount semeru east java indonesia with emphasis on lahars mt semeru the highest mountain in java 3 676 m is one of the few persistently active composite volcanoes on earth with a plain supporting about 1 million people we present the geology of the edifice review its historical eruptive activity and assess hazards posed by the current activity highlighting the lahar threat the composite andesite cone of semeru results from the growth of two edifices the mahameru old semeru and the seloko young semeru on the se flank of the summit cone a n130 trending scar branched on the active jonggring seloko vent is the current pathway for rockslides and pyroclastic flows produced by dome growth the eruptive activity recorded since 1818 shows three styles 1 the persistent vulcanian and phreatomagmatic regime consists of short lived eruption columns several times a day 2 increase in activity every 5 to 7 years produces several kilometer high eruption columns ballistic bombs and thick tephra fall around the vent and ash fall 40 km downwind dome extrusion in the vent and subsequent collapses produce block and ash flows that travel toward the se as far as 11 km from the summit and 3 flank lava flows erupted on the lower se and e flanks in 1895 and in 1941 1942 pyroclastic flows recur every 5 years on average while large scale lahars exceeding 5 million m3 each have occurred at least five times since 1884 lumajang a city home to 85 000 people located 35 km e of the summit was devastated by lahars in 1909 in 2000 the catchment of the curah lengkong river on the ese flank shows an annual sediment yield of 2 7 105 m3 km 2 and a denudation rate of 4 105 t km 2 yr 1 comparable with values reported at other active composite cones in wet environment unlike catchments affected by high magnitude eruptions sediment yield at mt semeru however does not decline drastically within the first post eruption years this is due to the daily supply of pyroclastic debris shed over the summit cone which is remobilised by runoff during the rainy season three hazard prone areas are delineated at mt semeru 1 a triangle shaped area open toward the se has been frequently swept by dome collapse avalanches and pyroclastic flows 2 the s and se valleys convey tens of rain triggered lahars each year within a distance of 20 km toward the ring plain 3 valleys 25 km s se and the ring plain 35 km e toward lumajang can be affected by debris avalanches and debris flows if the steep sided summit cone fails

two scales of inflation at lastarria cordon del azufre volcanic complex central andes revealed from asar envisat interferometric data abstract asar envisat interferometric synthetic aperture radar insar data collected over the lastarria cordon del azufre complex chile argentina between march 2003 and may 2005 show the persistence of the large wavelength ground inflation revealed by pritchard and simons in 2002 from the analysis of ers insar data nature 418 2002 167 170 after reducing the tropospheric contribution in the interferograms using a combination of data network adjustment and analysis of modis images we produced an accurate interferometric time series showing a 2 yr long temporal evolution of the ground displacements patterns two distinct inflating signals are detected the main signal covers an elliptical area with a 45 km nne ssw major axis and a 37 km minor axis it is correlated with a regional topographic dome we estimated its maximum inflation rate to 2 5 cm yr 1 we inverted the insar data for a range of source geometries spherical prolate ellipsoids penny shaped cracks the inferred source parameters for 2003 2005 period are consistent with an over pressured reservoir at shallow to intermediate crustal depths 7 15 km with an average volumetric rate of inflation of about 14 106 m3 yr 1 in addition to this main signal a new feature highlighted by the asar data is short wavelength inflation 6 km wide at the location of lastarria volcano on the northern margin of the large wavelength signal we explain this short wavelength signal by a spherical over pressured source lying 1000 m below the summit of lastarria volcano we estimate the average volumetric rate of inflation during the observation period to be 35 103 m3 yr 1 it is remarkable that both volumetric variations for the large and small inflations exhibit the same evolution during the 2003 2005 period suggesting that both processes could be related on the basis of the inversion results and of arguments provided by field evidences and a morpho structural analysis of the digital elevation model of the area we propose that the deep source have a magmatic origin while the shallow source is most likely related to hydrothermal fluids in our interpretation the on going deformation processes observed at lastarria cordon del azufre volcanic complex could represent an evolving pre caldera silicic system further field geological and geophysical investigations will be required to confirm these hypotheses and refine the proposed model mostly based on satellite observations

lake ecosystem dynamics and links to climate change inferred from a stable isotope and organic palaeorecord from a mountain lake in southwestern china ca 22 6 10 5 cal ka bp abstract a detailed understanding of long term climatic and environmental change in southwestern china is hampered by a lack of long term regional palaeorecords organic analysis toc tn c n ratios and 13c values of a sediment sequence from lake shudu yunnan province ca 22 6 10 5 cal ka bp indicates generally low aquatic palaeoproductivity rates over millennial timescales in response to cold dry climatic conditions however the record is punctuated by two marked phases of increased aquatic productivity from ca 17 7 to 17 1 cal ka bp and from ca 11 9 to 10 5 cal ka bp we hypothesise that these shifts reflect a marked stepwise lacustrine response to asian summer monsoon strengthening during the last deglaciation

pollen evidence of changing holocene monsoon climate in sichuan province china pollen evidence from lake shayema mianning county was obtained to examine postglacial vegetation and climatic change in southwestern sichuan china the sclerophyllous character of the region s warm temperate vegetation today is a reflection of extreme drought in spring before the onset of the asian monsoons the pollen record displays several changes in the vegetation over the last 11 000 yr from 11 000 to 9100 yr b p cold tolerant species such as abies betula and deciduous oaks dominated the vegetation between 9100 and 7800 yr b p the abundance of deciduous oaks decreased and evergreen oaks increased as did tsuga and mesic deciduous species this change suggests a warming climate with increased precipitation from 7800 to 4000 yr b p sclerophyllous species increased at the expense of mesic deciduous species an indication that precipitation was becoming more seasonal except for increased disturbance starting ca 1000 yr b p the predominance of sclerophyllous vegetation continued until today the pollen results are compatible with proposed global circulation hypotheses of a strengthened monsoon system during the early to mid holocene

aster watches the world s volcanoes a new paradigm for volcanological observations from orbit onboard nasa terra spacecraft is one of the most sophisticated earth observing instruments ever flown the advanced spaceborne thermal emission and reflection radiometer aster created as part of a joint project between the japanese ministry of economy trade and industry and nasa this instrument consists of three independent bore sighted telescopes with 14 channels in the visible near infrared and thermal infrared regions capable of being pointed up to 22 5 off nadir in addition there is an additional backward looking visible channel telescope for stereo photogrammetric observations the spatial resolutions are 15 m pixel in the visible 30 m pixel in the near ir and 90 m pixel at thermal wavelengths and the swath width is 60 km aster instrument offers unprecedented opportunities for observing volcanoes and their activity from low earth orbit it is the purpose of this short paper to introduce aster to the volcanological community highlight its capabilities advantages and limitations and to show some examples of aster data and related analyses we will also explain how users can readily access aster data

testing random forest classification for identifying lava flows and mapping age groups on a single landsat 8 image abstract mapping lava flows using satellite images is an important application of remote sensing in volcanology several volcanoes have been mapped through remote sensing using a wide range of data from optical to thermal infrared and radar images using techniques such as manual mapping supervised unsupervised classification and elevation subtraction so far spectral based mapping applications mainly focus on the use of traditional pixel based classifiers without much investigation into the added value of object based approaches and into advantages of using machine learning algorithms in this study nyamuragira characterized by a series of 20 overlapping lava flows erupted over the last century was used as a case study the random forest classifier was tested to map lava flows based on pixels and objects image classification was conducted for the 20 individual flows and for 8 groups of flows of similar age using a landsat 8 image and a dem of the volcano both at 30 meter spatial resolution results show that object based classification produces maps with continuous and homogeneous lava surfaces in agreement with the physical characteristics of lava flows while lava flows mapped through the pixel based classification are heterogeneous and fragmented including much salt and pepper noise in terms of accuracy both pixel based and object based classification performs well but the former results in higher accuracies than the latter except for mapping lava flow age groups without using topographic features it is concluded that despite spectral similarity lava flows of contrasting age can be well discriminated and mapped by means of image classification the classification approach demonstrated in this study only requires easily accessible image data and can be applied to other volcanoes as well if there is sufficient information to calibrate the mapping

high spatial resolution imagery helps map deposits of the large vei 4 2010 merapi volcano eruption and their impact the 26 october 23 november 2010 eruption is merapi s largest event vei 4 over the past 140 years we used high spatial resolution hsr imagery from geoeye pleiades ikonos and spot5 satellites to assess the extent and effects of the pyroclastic density currents pdcs and subsequent lahars we have tracked the geomorphic and structural fracturing changes of merapi s summit crater and dome between 2008 and 2012 the 4 september 2011 geoeye image shows that due to the explosive eruption the summit area lost about 10 106 m3 the eruption enlarged the sse trending gendol breach to be 1 3 0 3 0 2 km the 2010 tephra and pdc deposits covered about 26 km2 in the two catchments of gendol and opak rivers on merapi s south flank i e 60 75 of the total pdc deposit area with a total bulk volume of 45 106 m3 the tephra fall deposit covered an area of about 1300 km2 with a range in volume of 18 21 106 m3 supervised and object oriented classification on hsr imagery enables us to map in detail the pdc deposits across the gendol opak catchment we delineated 16 spectrally and or texturally distinct units of pdc deposits and compared them with previously published results they encompass high energy surge deposits within ca 8 km of the summit valley confined pdc deposits channeled as far as 16 5 km in the gendol river and widespread overbank pdc with ash cloud surge deposits on valley margins

early evolution of a stratospheric volcanic eruption cloud as observed with toms and avhrr this paper is a detailed study of remote sensing data from the total ozone mapping spectrometer toms and the advanced very high resolution radiometer avhrr satellite detectors of the 1982 eruption of el chichon mexico the volcanic cloud atmosphere interactions in the first four days of this eruption were investigated by combining ultraviolet retrievals to estimate the mass of sulfur dioxide in the volcanic cloud krueger et al 1995 with thermal infrared retrievals of the size optical depth and mass of fine grained 1 10 m radius volcanic ash wen and rose 1994 our study provides the first direct evidence of gravitational separation of ash from a stratospheric gas rich plinian eruption column and documents the marked differences in residence times of volcanic ash and sulfur dioxide in volcanic clouds the eruption column reached as high as 32 km carey and sigurdsson 1986 and was injected into an atmosphere with a strong wind shear which allowed for an observation of the separation of sulfur dioxide and volcanic ash the upper more sulfur dioxide rich part of the cloud was transported to the west in the stratosphere while the fine grained ash traveled to the south in the troposphere the mass of sulfur dioxide released was estimated at 7 1 109 kg with the mass decreasing by approximately 4 1 day after the peak the mass of fine grained volcanic ash detected was estimated at 6 5 109 kg amounting to about 0 7 of the estimated mass of the ash which fell out in the mapped ash blanket close to the volcano over the following days 98 of this remaining fine ash was removed from the volcanic cloud and the effective radius of ash in the volcanic cloud decreased from about 8 m to about 4 m

a 40 000 year palynological record from north east thailand implications for biogeography and palaeo environmental reconstruction abstract there are few palaeoenvironmental data from the indo chinese peninsula that document environmental and climatic conditions prior to the holocene this study of pollen and spores from a small peat swamp in north east thailand provides a record of vegetation change covering ca 40 000 years b p before present these data indicate that the region supported a fagaceous coniferous forest similar to contemporary vegetation described from south west china climatic conditions were cooler and probably drier than present day climates in thailand levels of biomass burning are relatively high throughout this period tropical broad leaf deciduous forest becomes dominant at the pleistocene holocene boundary with the fragmentation of fagaceous coniferous forest in response to increased temperatures

variations in organic matter composition in sediments from lake huguang maar huguangyan south china during the last 68 ka implications for environmental and climatic change abstract this study presents a continuous and long term palaeoenvironmental and palaeoclimatic record from a lacustrine sediment core lake huguang maar at the northern coast of the south china sea extending back to about 68 cal ka bp we provide a comprehensive ecosystem analysis from the opportunity to combine organic geochemical and palynological data several climatically induced changes to the flora and fauna have been recognised from 68 to 58 and 48 to 40 5 cal ka bp relatively depleted 13 c toc 31 3 to 25 0 and 13 c values of mid and long chain n alkanes 34 3 to 30 2 as well as high percentages of tropical pollen indicate a vegetation dominated by subtropical tropical forest c 3 plants an expansion of a mixed c 3 c 4 open grassland between 58 and 48 and particularly after 40 5 cal ka bp mirrors drier climatic conditions in conjunction with a lowering of atmospheric co 2 concentrations 13 c toc 24 1 to 16 8 and 13 c values of n alkyl lipids 28 9 to 24 1 are heavier higher percentages of non arboreal pollen were observed and the wood grass lignin index wgli from open pyrolysis py gc indicates a higher input of grass lignin abundant oxidised terrigenous particles that resulted from increased fire activity and or greater erosion rates are a further hint of enhanced dryness the clear drop in moisture availability suggests that this site is sensitive in fluctuations of the summer and winter monsoon activity in accordance with other proxy records in south east asia the response of the aquatic ecosystem is documented by an extremely large 13 c shift of algal derived botryococcenes from 35 4 to 6 2 which records a change towards a bicarbonate carbon source at low dissolved co 2 concentrations

lake evolution during the past 30 000 years in china and its implications for environmental change abstract taking china as a whole lake expansion occurred 500 b c 0 a d 650 950 a d and 1250 1650 a d over the past 3000 yr the expansions were mainly due to climatic fluctuations and correspond to frequent flood reports three regional characteristics of lake development have been recognized 1 fluctuations of near coastal lakes and those in other regions as well were out of phase during 500 b c 500 a d which possibly resulted from out of phase fluctuations of climate and sea level on 10 to 100 yr time scale 2 as the lower yellow river channel migrated southward the lakes in the south of the north china plain formed and reached their largest sizes much later than those in the north 3 for the lakes in the middle and lower yangtze river valley the higher a lake basin lies above a neighboring river and the further the lake is from the river s mouth in general the younger the lake is through land reclamation the ancient chinese have changed most of the lakes greatly however human activities were also constrained in certain ways by the natural changes of the lakes reclamation usually was banned and farmland was abandoned to repair reservoirs while lakes were expanding

flank cones at mount etna volcano do they have a power law distribution mount etna is currently characterised by intense effusive and explosive activity of its summit vents whereas 319 non active holocene flank cones are spread across its flanks at altitudes of between 2990 and 475 m in volcanic areas the relationships between fracture occurrence and cone growth location are well established with this in mind the spatial distribution of the mount etna flank cones was analysed in order to make some inferences about the fracture systems that feed the cones the positions of the flank cones were acquired by the use of a digital elevation model of the volcano with a geometric resolution of 10 10 m spatial distribution of the cones was analysed through counting box and sand box methods checking for fractal or multifractal behaviours the four data sets analysed consist of the whole number of parasitic cones 319 and cones located on the ne 50 south 143 and west 61 rifts respectively the cones have a non trivial power law distribution the sand box method gave the best results with a fractal exponent df for all cones of 1 41 0 02 over the length range 0 2 10 km the same analysis was performed on the other data sets south rift 1 42 0 02 west rift 1 39 0 02 and ne rift 1 43 0 02 the cones do not have a multifractal distribution as suggested also by the strong similarity between fractal exponents of the different data sets data suggest a strong control over flank cone distribution by fracture length and density these two characteristics are in turn expressions of highly connected fractures activated as magma feeders by the volcano s present stress field we interpret the rifts as inherited structures that represent preferential sites of fracture connectivity

remote sensing data types and techniques for lahar path detection a case study at mt ruapehu new zealand mt ruapehu is new zealand s most active onshore volcano in 2007 the volcano produced a large lahar following a break out from the summit crater lake here satellite and airborne remote sensing and image processing is used to extract the path of the lahar using aster and spot5 visible and near infra red imagery alos palsar l band synthetic aperture radar data and airborne lidar the results obtained from each of these datasets were compared to the lahar deposit manually digitized from aerial photography spot5 imagery produced the most accurate map of the lahar deposit 77 correct even though these data were acquired a year after the event this is attributed to the spatial resolution of the data the alos palsar coherence mapping calculated from images acquired 2 months before and nine months after the lahar was not as accurate as that obtained using the optical imagery 43 correct but this was still considered an important tool for acquiring data during cloudy periods lidar topographic data collected to constrain geomorphic changes caused by the lahar was the least accurate in terms of mapping the lahar path 28 correct no single technique was deemed to be the most accurate under all circumstances and a combination of data types would produce the best results by combining the satellite and lidar data it was possible to accurately classify 92 of the lahar path

the geological evolution of merapi volcano central java indonesia merapi is an almost persistently active basalt to basaltic andesite volcanic complex in central java indonesia and often referred to as the type volcano for small volume pyroclastic flows generated by gravitational lava dome failures merapi type nuees ardentes stratigraphic field data published and new radiocarbon ages in conjunction with a new set of 40k 40ar and 40ar 39ar ages and whole rock geochemical data allow a reassessment of the geological and geochemical evolution of the volcanic complex an adapted version of the published geological map of merapi wirakusumah et al 1989 peta geologi gunungapi merapi jawa tengah geologic map of merapi volcano central java 1 50 000 is presented in which eight main volcano stratigraphic units are distinguished linked to three main evolutionary stages of the volcanic complex proto merapi old merapi and new merapi construction of the merapi volcanic complex began after 170 ka the two earliest proto merapi volcanic edifices gunung bibi 109 60 ka a small basaltic andesite volcanic structure on merapi s north east flank and gunung turgo and gunung plawangan 138 3 ka 135 3 ka two basaltic hills in the southern sector of the volcano predate the merapi cone sensu stricto old merapi started to grow at 30 ka building a stratovolcano of basaltic andesite lavas and intercalated pyroclastic rocks this older merapi edifice was destroyed by one or possibly several flank failures the latest of which occurred after 4 8 1 5 ka and marks the end of the old merapi stage the construction of the recent merapi cone new merapi began afterwards mostly basaltic andesite pyroclastic and epiclastic deposits of both old and new merapi 11 792 90 14c years bp cover the lower flanks of the edifice a shift from medium k to high k character of the eruptive products occurred at 1 900 14c years bp with all younger products having high k affinity the radiocarbon record points towards an almost continuous activity of merapi since this time with periods of high eruption frequency interrupted by shorter intervals of apparently lower eruption rates which is reflected in the geochemical composition of the eruptive products the holocene stratigraphic record reveals that fountain collapse pyroclastic flows are a common phenomenon at merapi the distribution and run out distances of these flows have frequently exceeded those of the classic merapi type nuees ardentes of the recent activity widespread pumiceous fallout deposits testify the occurrence of moderate to large subplinian eruptions vei 3 4 during the mid to late holocene vei 4 eruptions as identified in the stratigraphic record are an order of magnitude larger than any recorded historical eruption of merapi except for the 1872 ad and possibly the october november 2010 events both types of eruptive and volcanic phenomena require careful consideration in long term hazard assessment at merapi

holocene monsoon changes inferred from lake sediment pollen and carbonate records northeastern cambodia major holocene monsoon changes in continental southeast asia are reconstructed from analysis of 14c dated changes in pollen and organic inorganic carbon in sediment cores taken from permanent closed basin volcanic lakes in ratanakiri province northeastern cambodia analysis focuses on the nature and timing of monsoon changes inferred from changes in vegetation and lake conditions these data provide the first well dated palynological record covering most of the holocene and continuous up to the present from a terrestrial site in mainland southeast asia the record from a 15 m core retrieved from kara lake representing the last 9300 years shows that the late glacial conditions ended about 8500 14c yr b p more than 1000 years later than sites in southwest china summer monsoon intensity increased over the period ca 8400 5300 14c yr b p similar to most other sites in the asian monsoon region a subsequent expansion of secondary forests at the expense of dense semievergreen forests suggest a drier climate leading to more frequent fire disturbance after ca 3500 14c yr b p disturbance frequency may have increased further with increasing seasonality from ca 2500 14c yr b p to the present dense forest has recovered in a mosaic with annually burned dry forest but climate may not be the main control on local vegetation dynamics in the late holocene

high resolution broad scale mapping of soil parent material using object based image analysis obia of lidar elevation data abstract precise mapping of subsurface properties especially soil parent material spm is critical to understanding most geomorphic and hydrologic processes because spatial variability of the subsurface properties is highly correlated to the morphology of the earth s surface dems and aerial satellite imagery have been used successfully for lithological mapping however most of the studies using this approach have used either coarse resolution dems or covered limited areas lidar derived topographic attributes may provide an opportunity for finer resolution mapping of subsurface properties at much larger spatial scales here we present an approach that uses object based image analysis obia the process of clustering pixels into homogeneous objects paired with a classification tree ct algorithm to map spm at 1 m resolution and at a regional spatial scale using lidar derived topographic attributes combining obia of topographic attributes with the ct method proved to be an efficient approach for mapping of spm at fine resolution and broad scales using field acquired spm samples we found that this approach was able to explain 73 5 of the variance of three spm classes i e bedrock glacial till sands using only four common topographic metrics i e slope topographic wetness index terrain ruggedness index multi resolution topographic positioning index when comparing our approach to other classification methods and to other studies that have mapped spm we obtain the highest overall accuracy with a value of 85 this approach allowed us to produce a fine resolution 185 km2 spm map in a heterogeneous post glaciation precambrian shield setting

holocene late pleistocene climatic ice core records from qinghai tibetan plateau three ice cores to bedrock from the dunde ice cap on the north central qinghai tibetan plateau of china provide a detailed record of holocene and wisconsin wurm late glacial stage lgs climate changes in the subtropics the records reveal that lgs conditions were apparently colder wetter and dustier than holocene conditions the lgs part of the cores is characterized by more negative 18 o ratios increased dust content decreased soluble aerosol concentrations and reduced ice crystal sizes than the holocene part these changes occurred rapidly 10 000 years ago in addition the last 60 years were apparently one of the warmest periods in the entire record equalling levels of the holocene maximum between 6000 and 8000 years ago

a high resolution absolute dated holocene and deglacial asian monsoon record from dongge cave china abstract we present a continuous record of the asian monsoon over the last 16 ka from 18o measurements of stalagmite calcite over 900 oxygen isotopic measurements providing information on shifts in monsoon precipitation are combined with a chronology from 45 precise 230th dates 18o and therefore asian monsoon intensity generally follows changes in insolation although changes in 18o are generally accommodated in abrupt shifts in contrast to smoothly varying insolation indicating that threshold effects may be important 18o decreased dramatically 3 at the start of the holocene 11 5 ka and remained low for 6 ka four positive 18o events centered at 11225 97 yr bp 1 05 10880 117 yr bp 1 15 9165 75 yr bp 1 4 and a double event centered at 8260 64 yr bp 1 1 and 8080 74 yr bp 1 0 punctuated this period of high monsoon intensity all four events correlate within error with climate changes in greenland ice cores thus the relationship between the asian monsoon and the north atlantic observed during the glacial period appears to continue into the early holocene in addition three of the four events correlate within error with outburst events from lake agassiz the decline of monsoon intensity in the mid late holocene is characterized by an abrupt positive shift in 18o which occurs at 3550 59 yr bp 1 1 in 100 yr in addition the holocene is punctuated by numerous centennial and multi decadal scale events amplitudes 0 5 to 1 up to half the amplitude of the glacial interstadial events seen in the last glacial period thus holocene centennial and multi decadal scale monsoon variability is significant although not as large as glacial millennial scale variability the monsoon shows a strong connection with northern south american hydrological changes related by changes in itcz position spectral analysis of the 18o record shows significant peaks at solar periodicities of 208 yr and 86 yr suggesting variation is influenced by solar forcing however there are numerous other significant peaks including peaks at el nino frequencies observed for high resolution portions of the record between 8110 and 8250 yr which suggest that changes in oceanic and atmospheric circulation patterns in addition to those forced by solar changes are important in controlling holocene monsoon climate in addition for this high resolution portion we observe a distinctive biennial oscillation of the asian monsoon which has been associated with the tropospheric biennial oscillation tbo

holocene treeline shifts and monsoon variability in the hengduan mountains southeastern tibetan plateau implications from palynological investigations abstract the upper 8 45 m of a sediment core from lake naleng were analysed for its pollen and charcoal content to detect vegetation climate and human activity changes on the southeastern tibetan plateau tp since the pleistocene holocene transition 11 7 cal kyr bp the application of pollen indicator taxa pollen sums biomisation and multivariate analysis helped to reconstruct environmental conditions during the holocene furthermore 64 surface samples from the southeastern tp and its foreland were analysed to investigate the relationship between modern pollen assemblages and vegetation the modern vegetation was recorded in the surface pollen assemblages by pollen indicator types although sediments also contain pollen spectra extra regional pollen transported from lower vegetation belts which is seen as a consequence of steep elevation gradients at the southeastern margin of the tp the relation between different vegetation belts and temperature from the modern sample sites was used to infer quantitative temperature trends for the holocene record spreading of forests at the beginning of the holocene marks the transition to warmer conditions from 10 7 to 4 4 cal kyr bp open abies betula forests were found at lake naleng probably reflecting a stronger than present summer monsoon temperature range reconstructions suggest a temperature that was about 2 3 c warmer and a treeline position that was 400 600 m higher than today a severe climate deterioration with temperatures about 1 2 c colder than before is documented by a retreating forest between 8 1 and 7 2 cal kyr bp forests retreated while subalpine rhododendron shrubs spread around lake naleng indicating colder conditions with temperatures 1 2 c below early and mid holocene level after 4 4 cal kyr bp the forest decline at 4 4 cal kyr bp is considered to reflect climatic conditions as low concentrations of charcoal particles found in this period exclude human induced fires as reason for the forest retreat however grazing indicators imply human influence on the environment since 3 4 cal kyr bp around lake naleng we therefore consider the rapid treeline shift seen at 3 4 cal kyr bp as partly generated by human activity and partly by climatic conditions

palaeoclimate dynamics in continental southeast asia over the last 30 000calyrs bp abstract although the asian monsoon is the dominant source of precipitation across continental southeast asia projections of future climate trends in this region remain unclear this is partly because historic climate records are relatively short precluding our ability to understand long term climate dynamics and potential drivers of change in this synthesis 17 palaeorecords from sites located in continental southeast asia provide a synopsis of regional palaeoclimate dynamics over the last 30 000 cal yrs bp the results indicate that over millennial timescales the dominant control on asian monsoon intensity is solar insolation linked to orbital changes from ca 30 to 11 9 cal kyr bp climatic conditions are interpreted to have been cold and arid most probably dominated by a strong asian winter monsoon marked changes occurred during the pleistocene holocene transition including a shift to warmer wetter climatic conditions at ca 11 5 cal kyr bp which was apparently synchronous across the region during the early to mid holocene warmer wetter climatic conditions were established consistent with a strong asian summer monsoon inferred from the dongge cave 18o speleothem record intriguingly contrasting sub regional palaeoclimatic trends are captured in the synthesis most notably during the holocene possibly due to differing sub regional climatic and environmental influences including differences in the role of the asian monsoon the westerlies and or topographical effects however because of uncertainties relating to the age control of many of the palaeorecords it is not possible to make this interpretation with confidence further work involving comprehensive radiocarbon dating of sequences and the development of high resolution palaeoclimatic reconstructions are urgently required if we are to identify decadal to centennial scale changes across continental southeast asia and test hypotheses of synchroneity in the region

a high resolution absolute dated late pleistocene monsoon record from hulu cave china oxygen isotope records of five stalagmites from hulu cave near nanjing bear a remarkable resemblance to oxygen isotope records from greenland ice cores suggesting that east asian monsoon intensity changed in concert with greenland temperature between 11 000 and 75 000 years before the present yr b p between 11 000 and 30 000 yr b p the timing of changes in the monsoon as established with 230th dates generally agrees with the timing of temperature changes from the greenland ice sheet project two gisp2 core which supports gisp2 s chronology in this interval our record links north atlantic climate with the meridional transport of heat and moisture from the warmest part of the ocean where the summer east asian monsoon originates

evaluating titan2d mass flow model using the 1963 little tahoma peak avalanches mount rainier washington the titan2d geophysical mass flow model is evaluated by comparing its simulation results and those obtained from another flow model flow3d with published data on the 1963 little tahoma peak avalanches on mount rainier washington the avalanches totaling approximately 10 10 6 m 3 of broken lava blocks and other debris traveled 6 8 km horizontally and fell 1 8 km vertically h l 0 246 velocities calculated from runup range from 24 to 42 m s and may have been as high as 130 m s while the avalanches passed over emmons glacier titan2d is a code for an incompressible coulomb continuum it is a depth averaged dshallow watert granular flow model the conservation equations for mass and momentum are solved with a coulomb type friction term at the basal interface the governing equations are solved on multiple processors using a parallel adaptive mesh godunov scheme adaptive gridding dynamically concentrates computing power in regions of special interest mesh refinement and coarsening key on the perimeter of the moving avalanche the model flow initiates as a pile defined as an ellipsoid by a height z and an elliptical base defined by radii in the x and y planes flow parameters are the internal friction angle and bed friction angle results from the model are similar in terms of velocity history lateral spreading location of runup areas and final distribution of the little tahoma peak deposit the avalanches passed over the emmons glacier along their upper flow paths but lower in the valley they traversed stream gravels and glacial outwash deposits this presents difficulty in assigning an appropriate bed friction angle for the entire deposit incorporation of variable bed friction angles into the model using gis will help to resolve this issue d 2004 elsevier b v all rights reserved

late glacial vegetation and climate oscillations on the southeastern tibetan plateau inferred from the lake naleng pollen profile we present a late glacial pollen record 17 700 to 8500 cal yr bp from a lake naleng sediment core lake naleng is located on the southeastern tibetan plateau 31 10 n 99 75 e 4200 m along the upper tree line variations in the summer monsoon are evident from shifts in vegetation that correspond to late glacial climate trends from other monsoon sensitive regions alpine steppe was recorded between 17 700 and 14 800 cal yr bp indicating low effective moisture at the study site expansion of alpine meadows followed by advances in the position of tree line around lake naleng suggest that climate became warmer and wetter between 14 800 and 12 500 cal yr bp probably representing an enhancement of the asian monsoon climatic cooling and reduced effective moisture are inferred from multivariate analysis and the upward retreat of tree line between 12 500 and 11 700 cal yr bp the timing and nature of these shifts to warm wet and then cold dry climatic conditions suggest that they correspond to the bolling allerod and younger dryas intervals abies betula forests representing warm and moist conditions spread during the early holocene

topographic analyses of k lauea volcano hawai i from interferometric airborne radar we analyze digital topographic data collected in september 1993 over a 500 km2 portion of k lauea volcano hawai i by the c band 5 6 cm wavelength topographic synthetic aperture radar topsar airborne interferometric radar field surveys covering an 1 km2 area of the summit caldera and the distal end of an 8 m thick a flow indicate that the 10 m spatial resolution topsar data have a vertical accuracy of 1 2 m over a variety of volcanic surfaces after conversion to a common datum topsar data agree favorably with a digital elevation model dem produced by the u s geological survey usgs with the important exception of the region of the ongoing eruption which postdates the usgs dem this dem comparison gives us confidence that subtracting the usgs data from topsar data will produce a reasonable estimate of the erupted volume as of september 1993 this subtraction produces dense rock equivalent dre volumes of 392 439 and 90 106 m3 for the pu u k pa ianah and episode 50 53 stages of the eruption respectively these are 124 89 and 94 of the volumes calculated by staff of the hawaiian volcano observatory hvo but do not include lava of k pa ianah and episodes 50 53 that flowed into the ocean and are thus invisible to topsar accounting for this lava increases the topsar volumes to 124 159 and 129 of the hvo volumes including the 2 m uncertainty derived from the field surveys produces topsar derived volumes for the eruption as a whole that range between 81 and 125 of the usgs derived values the vesicularity and ocean corrected topsar volumes yield volumetric eruption rates of 4 5 4 5 and 2 7 m3 s for the three stages of the eruption which compare with hvo derived values of 3 6 2 8 and 2 1 m3 s respectively our analysis shows that care must be taken when vertically registering the topsar and usgs dems to a common datum because c band topsar penetrates only partially into thick forest and therefore produces a dem within the tree canopy whereas the usgs dem is adjusted for vegetation

mechanisms forcing abrupt fluctuations of the indian ocean summer monsoon during the last deglaciation abstract a piston core from the somali upwelling area has been studied at high resolution for its dinoflagellate cyst content variations in cyst association are inferred to reflect changes in indian ocean summer monsoon intensity several abrupt fluctuations in monsoon intensity are detected for the interval between 20 and 10 ka bp comparison of these fluctuations with changes in contrast between 30 n and 30 s july insolation and the 18 o grip ice core values suggests that different mechanisms influenced monsoon intensity at different time intervals a general trend in monsoon intensity follows variations in insolation contrast lagging minimum contrast by 7 5 ka and maximum contrast by 4 ka this phase lag difference can be explained by assuming the existence of an ice snow cover over central asia tibet during glacial times between 18 7 and 12 5 ka bp fluctuations in sw monsoon intensity may be forced by variations in the thermohaline ocean circulation a rapid transition towards strong sw monsoons at 12 5 ka bp is possibly the result of variations in atmospheric circulation and melting of the snow ice fields in central asia tibet variations in glacial interglacial boundary conditions related to temperature change at northern latitudes are likely to have influenced sw monsoon intensity between 12 5 and 10 ka bp whereas after 10 ka bp variations in tropical land surface boundary conditions may be the dominant forcing factor 0 1997 elsevier science ltd all rights reserved

distinct climate change synchronous with heinrich event one recorded by stable oxygen and carbon isotopic compositions in stalagmites from china abstract uranium series dating of oxygen and carbon isotope records for stalagmite sj3 collected in songjia cave central china shows significant variation in past climate and environment during the period 20 10 ka stalagmite sj3 is located more than 1000 km inland of the coastal hulu cave in east china and more than 700 km north of the dongge cave in southwest china and despite minor differences displays a clear first order similarity with the hulu and dongge records the coldest climatic phase since the last glacial maximum which is associated with the heinrich event 1 in the north atlantic region was clearly recorded in sj3 between 17 6 and 14 5 ka in good agreement in timing duration and extent with the records from hulu and dongge caves and the greenland ice core the results indicate that there have been synchronous and significant climatic changes across monsoonal china and strong teleconnections between the north atlantic and east asia regions during the period 20 10 ka this is much different from the holocene optimum which shows a time shift of more than several thousands years from southeast coastal to inland china it is likely that temperature change at northern high latitudes during glacial periods exerts stronger influence on the asian summer monsoon relative to insolation and appears to be capable of perturbing large scale atmospheric oceanic circulation patterns in the northern hemisphere and thus monsoonal rainfall and paleovegetation in east asia climatic signals in the north atlantic region propagate rapidly to east asia during glacial periods by influencing the winter land sea temperature contrast in the east asian monsoon region

evolution and variability of the asian monsoon system state of the art and outstanding issues the asian monsoon is comprised of the indian and east asian subsystems these two components are linked to one another in varying degrees by regions of strong sensible heating indo asian landmass and strong latent heat export the western pacific warm pool and the southern subtropical indian ocean variability within the indian and east asian subsystems interactions among them and the extent to which they interact with other climate phenomena e g enso are current topics of modern and paleoclimate research this work provides an overview of past and current paleomonsoon research on tectonic to interannual time scales with a primary focus on marine sediment records while past and current work has contributed greatly to our understanding of paleomonsoon variability at all time scales additional efforts are required to make further progress in two critical areas 1 additional efforts are needed in terms of proxy development and evaluation requiring concerted efforts at long term sediment trap deployments in key monsoon influenced regions as well as development of adequate and widely available core top databases these are necessary to assess the impact of modern oceanographic and seafloor processes on potential monsoon proxies 2 additional effort is also needed in acquiring a sufficient geographic distribution of downcore records to assess linkages among the subsystems and their role in the context of extratropical climate change these records should have high sedimentation rates including varved sections this requires substantial survey support to identify the most appropriate coring and drilling targets c 2004 elsevier ltd all rights reserved