large wood recruitment processes and transported volumes in swiss mountain streams during the extreme flood of august 2005 abstract the extreme flood event that occurred in august 2005 was the most costly documented natural hazard event in the history of switzerland the flood was accompanied by the mobilization of 69 000 m3 of large wood lw throughout the affected area as recognized afterward wood played an important role in exacerbating the damages mainly because of log jams at bridges and weirs the present study aimed at assessing the risk posed by wood in various catchments by investigating the amount and spatial variability of recruited and transported lw data regarding lw quantities were obtained by field surveys remote sensing techniques lidar and gis analysis and was subsequently translated into a conceptual model of wood transport mass balance detailed wood budgets and transport diagrams were established for four study catchments of swiss mountain streams showing the spatial variability of lw recruitment and deposition despite some uncertainties with regard to parameter assumptions the sum of reconstructed wood input and observed deposition volumes agree reasonably well mass wasting such as landslides and debris flows were the dominant recruitment processes in headwater streams in contrast lw recruitment from lateral bank erosion became significant in the lower part of mountain streams where the catchment reached a size of about 100 km2 according to our analysis 88 of the reconstructed total wood input was fresh i e coming from living trees that were recruited from adjacent areas during the event this implies an average deadwood contribution of 12 most of which was estimated to have been in channel deadwood entrained during the flood event

converted phases analysis of the campi flegrei caldera using active seismic data abstract we applied a type of depth migration for converted seismic phases to active and passive seismic data sets from the campi flegrei volcanic region in southern italy the migration method is based on the diffraction summation migration technique travel times to grid points in a volume were calculated in smooth p and s velocity models and trace energy near the calculated converted phase time was stacked over multiple sources at one receiver weighting factors based on snell s law at an arbitrarily oriented local interface were applied to better focus trace energy pp reflection images from the active data set provide increased detail to images of the caldera rim from other studies the migrated images also show features near 2 3 km in depth beneath pozzuoli city which may be associated with an over pressured gas volume as suggested by other geophysical investigations possible deeper features near 4 km depth may be related to the presence of the carbonate basement or may image a previously undetected feature such as a small body of strongly thermometamorphosed volcanic rock the current passive earthquake data set from the 1984 ground uplift episode was not well suited to the converted phases analysis due to narrow p s windows and high noise levels in the traces however two stations provide confirmation and extension of imaged features in the active data

deformation and stress in hydrothermal regions the case of a disk shaped inclusion in a half space abstract hydrothermal regions are affected by a wide variety of phenomena including ground inflation and deflation episodes among them calderas offer the opportunity to study the complex interactions between magmatic processes at depth and permeable rocks saturated with fluids in the upper sedimentary layers one of such regions is the campi flegrei caldera in southern italy where several source models have been applied over the years to reproduce the ground displacement and seismicity observed during the most recent phase of major unrest 1982 1984 the present work aims at introducing a new source model consisting of a thermo poro elastic inclusion embedded in a homogeneous poroelastic half space the inclusion is meant to represent a permeable rock layer stressed and strained by hot and pressurized volatiles released upward by an underlying magmatic reservoir and is modeled as a thin horizontal disk inside which a sudden change of temperature and pore pressure occurs we provide semi analytical solutions for the displacement and stress fields both within and outside the source and check them by comparison with those obtained through a fully numerical approach results provided by our model are compared with two other deformation source models often used to describe volcanic environments in terms of pressurized cavities describing a spherical magma chamber mogi source or a sill like magma intrusion fialko source for the campi flegrei 1982 84 unrest our model provides a better reproduction of ground deformation data and manages to explain the widespread presence of compressive focal mechanisms since the stress field promoted both inside and outside the thermo poro elastic inclusion is very different from pressurized cavities

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

a model of slope formation related to landslide activity in the eastern prealps austria abstract the rhenodanubian flysch zone of the eastern alps of austria is considered to be susceptible to landslides in the study area an undulating low mountain landscape of the eastern european prealps the flysch bedrock is superimposed by quaternary periglacial cover beds and loess both the petrography of the bedrock and the soil mechanical properties of quaternary sediments control the slope dynamics a database compiled for the study area comprises about 200 datasets on landslide and rock fall hazards it covers a time span between 1771 and 2007 and shows clusters between 1940 and 1943 1965 and 1966 1979 and 1982 as well as in 2006 the study analyses slope stability in the light of slope formation phases with respect to weathering erosion and geology furthermore geomorphological and soil geographical methods are combined with soil mechanical calculations the application of the concept of periglacial cover beds facilitates the distinction between holocene and pleistocene landforms and slide masses in the research area as a result the study shows that the properties of quaternary sediments and the occurrence of the densely bedded basal cover beds are responsible for landslide susceptibility the variable permeability in loess layers in contrast to that in the underlying basal cover beds consisting mainly of marls and clayey material is one of the fundamental controlling factors of mass movements in a temporal context it is evident that the stability of slopes in the study area is influenced by several phases of slope formation the synopsis of field survey morphometrical geotechnical as well as laboratory analyses and slope stability calculation gives evidence of five morphodynamic phases that partly reoccur in an alternating pattern after having passed all phases the stability of the slopes studied is increased because modified soil mechanical properties of the slide masses become important as a consequence the critical slope angle is raised by 3 5

poisson s ratio and porosity at coso geothermal area california high resolution three dimensional compressional and shear wave velocity models derived from microearthquake traveltimes are used to map the distribution of poisson s ratio and porosity at coso geothermal area inyo county california spatial resolution of the three dimensional poisson s ratio and porosity distributions is estimated to be 0 5 km horizontally and 0 8 km vertically model uncertainties 1 in the interior and 2 3 around the edge of the model are estimated by a jackknife method we use perturbations of r vp vs ratio and vp vs product to derive distributions of poisson s ratio and porosity which are then used to constrain and delineate possible zones of intense heat fracture accumulation and fluid saturation poisson s ratio at coso ranges from 0 15 to 0 35 with an average of 0 224 lower than the crustal average of 0 25 high poisson s ratios are more extensive in shallower depths 1 5 km while lower poisson s ratios are found in the deeper section 1 5 3 0 km of the target area two major features with low poisson s ratio are identified at geothermal production depth 1 3 km around stations s2 s6 and s1 s3 s4 the two low features are separated by a northwest southeast trending high belt with variable width of 1 3 km a high body is found around s2 and s6 and extends down in depth a circular low belt corresponding to the high belt is located around s2 s6 and is linked to a previously reported structure in vs tomography this low highly porous belt is probably a horizontal conduit reservoir of geothermal fluid a vertical low and high channel beneath triangle s1 s3 s4 corresponds to a high attenuation dome like feature we propose an upwell and spread magma intrusion model for the last major magmatism in the coso region the magmatic upwelling is centered in the s1 s3 s4 area the model predicts potential geothermal resources to the south and west of triangle s1 s3 s4 based on local faulting patterns

geomorphological and sedimentological analysis of a catastrophic flash flood in the aras drainage basin central pyrenees spain abstract on august 7th 1996 an intense and short duration convective storm occurred over the 18 6 km 2 aras drainage basin central pyrenees spain this high relief basin is composed of three subbasins aso betes and la selva and feeds the aras alluvial fan in the gallego river valley this alluvial fan had been drained by an artificial channel about 125 m 3 s at bank full capacity more than 30 check dams in its feeder channel the aras barranco had been previously filled by earlier sediments the heaviest rain was over the betes subbasin total rainfall 178 4 mm maximum rainfall intensity of 153 mm h for a 10 min time interval was estimated most of the rainfall fell in a 70 min period this storm resulted in high runoff causing catastrophic damage and significant geomorphic changes in the drainage basin especially in the betes subbasin the high discharge concentrated in the aras barranco destroyed most of the check dams flushing out a great amount of debris major channel trenching and widening occurred in this barranco when the confined sediment laden flash flood reached the basin mouth it sheet flooded the southern sector of the aras fan depositing a massive amount of debris on this fan 87 people lost their lives and the direct physical damage has been estimated at 55 million dollars two stages in the development of the flood have been differentiated from the sedimentological and morphological analysis of the flooded fan lobe a first stage peak discharge of sheet flooding deposited a coarse boulder lobe burying the artificial channel at the fan head and causing a darnming effect on the water flood during the second stage discharge decline the flood made its way through the fan head incising the previous debris accumulation and splitting into two main flow paths

deep sea records of the continental weathering and erosion response to east asian monsoon intensification since 14 ka in the south china sea we analyzed sediment from ocean drilling program odp site 1144 in the northern south china sea to examine the weathering response of se asia to the strengthening of the east asian monsoon eam since 14 ka our high resolution record highlights the decoupling between continental chemical weathering physical erosion and summer monsoon intensity mass accumulation rates ti ca k rb hematite goethite and sr 87 sr 86 show sharp excursions from 11 to 8 ka peaking at 10 ka clay minerals show a shorter lived response with a higher kaolinite illite chlorite ratio at 10 7 9 5 ka however not all proxies show a clear response to environmental changes magnetic susceptibility rises sharply between 12 and 11 ka grain size becomes finer from 14 to 10 ka and then coarsens until similar to 7 ka but is probably controlled by bottom current flow and sealevel sr and nd isotopes show that material is dominantly eroded from taiwan with a lesser flux from luzon while clay mineralogy suggests that the primary sources during the early holocene were reworked via the shelf in the taiwan strait rather than directly from taiwan erosion was enhanced during monsoon strengthening and caused reworking of chemically weathered pleistocene sediment largely from the now flooded taiwan strait which was transgressed by similar to 8 ka cutting off supply to the deep water slope none of the proxies shows an erosional response lasting until similar to 6 ka when speleothem oxygen isotope records indicate the start of monsoon weakening although more weathered sediments were deposited from 11 to 8 ka when the monsoon was strong these are reworked and represent more weathering during the last glacial maximum lgm when the summer monsoon was weaker but the shelves were exposed c 2012 elsevier b v all rights reserved

three dimensional seismic tomography from p wave and s wave microearthquake travel times and rock physics characterization of the campi flegrei caldera 1 the campi flegrei cf caldera experiences dramatic ground deformations unsurpassed anywhere in the world the source responsible for this phenomenon is still debated with the aim of exploring the structure of the caldera as well as the role of hydrothermal fluids on velocity changes a multidisciplinary approach dealing with three dimensional delay time tomography and rock physics characterization has been followed selected seismic data were modeled by using a tomographic method based on an accurate finite difference travel time computation which simultaneously inverts p wave and s wave first arrival times for both velocity model parameters and hypocenter locations the retrieved p wave and s wave velocity images as well as the deduced v p v s images were interpreted by using experimental measurements of rock physical properties on cf samples to take into account steam water phase transition mechanisms affecting p wave and s wave velocities also modeling of petrophysical properties for site relevant rocks constrains the role of overpressured fluids on velocity a flat and low v p v s anomaly lies at 4 km depth under the city of pozzuoli earthquakes are located at the top of this anomaly this anomaly implies the presence of fractured overpressured gas bearing formations and excludes the presence of melted rocks at shallow depth a high v p v s anomaly located at 1 km suggests the presence of rocks containing fluids in the liquid phase finally maps of the v p v s product show a high v p v s horseshoe shaped anomaly located at 2 km depth it is consistent with gravity data and well data and might constitute the on land remainder of the caldera rim detected below sea level by tomography using active source seismic data

asian summer monsoonal variations during the holocene revealed by huguangyan maar lake sediment record abstract high resolution records of summer monsoonal evolution in the holocene are essential to paleoclimate reconstruction but are hard to obtain here we provide a continuous well dated high resolution record from huguangyan maar lake located in the west pacific climate regime multi proxies including chlorophyll a toc sr rb ratio and magnetic susceptibility have been used to reconstruct the monsoon variations in the holocene higher chlorophyll a values are related with stronger summer monsoon and vice versa high temporal resolution radiocarbon dating enables us to divide summer monsoon evolution stages summer monsoon in zhanjiang area was strongest in the early holocene but began to decline at 6080 yr bp and weakened substantially since about 3600 yr bp the transition around 6080 yr bp supported by our high resolution dating lags the previous estimates by 1700 years the decreasing summer solar radiation at 30 n through the holocene is probably responsible for gradually weakened summer monsoon the anti phased co variation of summer monsoon intensity and enso activity throughout the holocene suggests that they could be interlinked driven together by solar radiation at orbital scale

persistent solar influence on north atlantic climate during the holocene surface winds and surface ocean hydrography in the subpolar north atlantic appear to have been influenced by variations in solar output through the entire holocene the evidence comes from a close correlation between inferred changes in production rates of the cosmogenic nuclides carbon 14 and beryllium 10 and centennial to millennial time scale changes in proxies of drift ice measured in deep sea sediment cores a solar forcing mechanism therefore may underlie at least the holocene segment of the north atlantic9s 1500 year cycle the surface hydrographic changes may have affected production of north atlantic deep water potentially providing an additional mechanism for amplifying the solar signals and transmitting them globally

tomographic images and 3d earthquake locations of the seismic swarm preceding the 2001 mt etna eruption evidence for a dyke intrusion 1 on july 12 2001 mt etna experienced a sudden increase of seismic activity heralding one of the most intense eruptions of the past 30 years between july 12 and july 18 when the eruption started thousands of small magnitude earthquakes occurred and were recorded by a dense seismic network run by the istituto nazionale di geofisica e vulcanologia sezione di catania ingv ct hypocentral depths of earthquakes were very shallow mostly located above 3 km b s l and clustered near the summit area the high quality seismic dataset gives us the unique opportunity to study the process of magma migration before the eruption in this study we present the three dimensional earthquake locations and the velocity structure obtained by a tomographic inversion the shallowness of seismicity allowed us to enhance the details of the structure beneath the summit craters in a volume poorly defined by previous tomographic studies the presence of a high vp body previously observed at mt etna is confirmed at shallow depth beneath the southeastern part of the summit area the earthquakes preceding the eruption onset concentrated at its western border a low vp vs anomaly is found at 0 1 km depth just at the top of the volume where the magma intruded before the eruption this anomalous zone can be considered as molten material wealthy in gas the relocated seismicity occurs in a cylinder below the vents activated along the fracture system and exhibited an upward migration until the eruption all these results show evidence for the emplacement of a near vertical dyke striking about n s and a few kilometres south of the summit craters

principal component analysis of msbas dinsar time series from campi flegrei italy abstract because of its proximity to the city of naples and with a population of nearly 1 million people within its caldera campi flegrei is one of the highest risk volcanic areas in the world since the last major eruption in 1538 the caldera has undergone frequent episodes of ground subsidence and uplift accompanied by seismic activity that has been interpreted as the result of a stationary deeper source below the caldera that feeds shallower eruptions however the location and depth of the deeper source is not well characterized and its relationship to current activity is poorly understood recently a significant increase in the uplift rate has occurred resulting in almost 13 cm of uplift by 2013 de martino et al 2014 samsonov et al 2014b di vito et al 2016 here we apply a principal component decomposition to high resolution time series from the region produced by the advanced multidimensional sbas dinsar technique in order to better delineate both the deeper source and the recent shallow activity we analyzed both a period of substantial subsidence 1993 1999 and a second of significant uplift 2007 2013 and inverted the associated vertical surface displacement for the most likely source models results suggest that the underlying dynamics of the caldera changed in the late 1990s from one in which the primary signal arises from a shallow deflating source above a deeper expanding source to one dominated by a shallow inflating source in general the shallow source lies between 2700 and 3400 m below the caldera while the deeper source lies at 7600 m or more in depth the combination of principal component analysis with high resolution msbas time series data allows for these new insights and confirms the applicability of both to areas at risk from dynamic natural hazards

incorporation of bed texture into a channel evolution model abstract channel evolution models cem have been developed to qualitatively describe the morphological adjustments of channels undergoing incision but the grain size of the river bed material has not been addressed in existing evolution models herein bed material grain size is incorporated into an existing cem to describe the sequence of grain size changes the analysis is based on the data from bed material that were available from a 1986 sampling program in northwestern mississippi samples were taken along three sand and gravel bed channels at 300 m intervals to provide a comparable data set sampling was repeated in 1996 observed longitudinal grain size distributions were highly variable in space and time overall downstream fining trends were absent bed texture in incising channels is as dynamic as channel morphology with composition shifting from a mixture dominated by sand to one dominated by gravel or vice versa within a decade or less the modified cem predicted direction of changes in grain size in a meandering incising channel but not within two straightened incising channels most likely due to the complex influence of upstream and lateral sediment sources bed and bank erosion we suggest that over the temporal 10 years and spatial scales 10 to 20 km of this study sediment sources are the dominant factor in the development of longitudinal grain size distributions

a 6000 year record of changes in drought and precipitation in northeastern china based on a δ13c time series from peat cellulose we report a new peat delta c 13 proxy record for humidity or precipitation based on c3 plants from northeastern china the record reveals two times of significant climate shift and eight severe drought periods during the past 6000 years all of which have the nature of widespread global occurrence the variability of precipitation shows periodicities of around 70 80 90 107 110 123 134 141 162 198 205 249 278 324 389 467 584 834 and 1060 years the occurrence and persistent times of drought and periodicities of precipitation show good correspondence with solar variability the remarkable correlations between peat delta c 13 peat delta o 18 and atmospheric delta c 14 suggest that on timescales of decades to centuries the changes in drought and precipitation are likely caused by variations of atmospheric circulation and atmosphere ocean interactions in large scale patterns that seem to be related to solar variability c 2001 elsevier science b v all rights reserved

marine palynological record for tropical climate variations since the late last glacial maximum in the northern south china sea the upper part 191 1439 cm of the marine sediment core md05 2906 from the northern south china sea scs was palynologically investigated the chronology suggested that it covered the record since 19 calendar kiloyears before present cal ka bp and revealed a detailed environmental change history since the late last glacial maximum lgm during the late lgm due to the lowered sea level 100 m lower and the shortened distance from the shore to the study site the pollen concentration was very high the pollen assemblages were dominated by non arboreal taxa especially artemisia pollen before 15 cal ka bp abundant subtropical and tropical pollen taxa were still important components and a south subtropical climate prevailed during the late lgm the coexistent rich artemisia pollen possibly was not derived from near shores but was derived mainly from the northern exposed continental shelf in the east china sea ecs after 15 cal ka bp with the rise in the sea level and enhanced distance from the pollen source areas to the core site pollen concentrations started to decline gradually however during the late deglaciation and early holocene the higher concentrations of many pollen taxa reoccurred which cannot be attributed to the sea level changes pinus pollen deposited in the core which is considered to be mostly water carried based on many modern pollen surveys also started to dramatically increase at the same time therefore the higher pollen concentration with more pinus and typha an aquatic plant pollen indicated a notably enhanced terrestrial runoff and precipitation during the last deglaciation holocene transition 11 3 9 4 cal ka bp we inferred that a strong summer monsoon occurred at this time during the late lgm deglaciation transition period the pollen assemblage reflected a gradually warming climate and the climate fluctuations derived from the high latitudes were not well identified this study suggests that solar insolation played a crucial role in controlling the east asian monsoon and hydrological cycle in the northern scs

reconstruction of late glacial and holocene climate evolution in southern china from geolipids and pollen in the dingnan peat sequence we have carried out a multi proxy analysis of a radiocarbon dated peat core that records the history of paleoclimate change dating from 18 ka in the dingnan region of southern china fatty acid and hydrocarbon distributions total organic carbon toc concentrations pollen assemblages and sediment lithology reveal a succession of three major paleoclimate intervals plant waxes are the predominant origin of the n alkanoic acid and n alkane compositions of this sedimentary sequence contributions of these geolipid components vary relative to toc and with changes in lithology and help to refine a pollen based reconstruction of local paleoclimate evolution a period of cool and fairly wet climate 15 630 10 450 cal abp follows accumulation of coarse fluvial sediments under relatively dry deglacial conditions the second period 10 450 6040 cal abp experienced the warmest climate and the highest precipitation indicated by a minimum c18 1 c18 0 ratio together with the low cpi values of n alkanes and high acl values the third time interval 6040 3800 cal abp was a moderately dry and cool period the climate record of the most recent period 3800 cal abp is obscured by agricultural disturbance the younger dryas 12 900 11 600 cal abp appears in this record as a period of variable and very wet climate during the interval 10 450 6040 cal abp both temperature and the precipitation evaporation ratio maximized therefore we consider this period to represent the holocene optimum which coincides with that of the northern hemisphere moreover our results do not fit the spatially asynchronous pattern of the east asian monsoon holocene optimum in china suggested by previous studies they instead parallel the pattern of global paleoclimate change and consequently show that the evolution of holocene paleoclimate in southern china is consistent with changes in northern hemisphere solar radiation

geochemical records of taiwan sourced sediments in the south china sea linked to holocene climate changes we present a multi proxy geochemical analysis of core kng5 retrieved from the northern south china sea slope spanning the last 13 0 ka bp to assess the response of weathering and erosion processes in the southwestern taiwan river basin to climate change a provenance analysis indicates that the core sediments were primarily derived from the southwestern taiwan river and can be used to reconstruct the erosion and or weathering history of this river basin the chemical index of alteration the plagioclase index of alteration rb sr al ti principle component 1 and k al combined with terrigenous mass accumulation rates and the proportion of clay exhibit sharp excursions from 12 0 to 5 5 ka peaking at 10 0 ka which suggests strong chemical weathering and physical erosion during the early mid holocene the period of the maximum summer monsoon abrupt falling weathering trends during 5 2 and 3 5 ka bp correlate with a weaker monsoon after 3 5 ka bp a stable lower weathering trend to the present day was evident indicating the deposition of less weathered sediments in the slope when the monsoon rainfall was weakening a good correlation between our proxy records of chemical weathering and variations of the monsoon intensity in south china emphasizes that variation in monsoon intensity is most likely the primary drive of the intensity of weathering and erosion in southwestern taiwan river sediments over the last 13 0 ka bp finally we concluded that geochemical parameters can be used as reliable proxies for climate variation on a millennial centennial time scale in such areas as taiwan where weathering limited regimes exist c 2015 elsevier b v all rights reserved

active channel width as a proxy of sediment supply from mining sites in new caledonia although the channel morphology of upland fluvial systems is known to be strongly controlled by sediment supply from hillslopes it is still difficult to isolate this effect from the other controlling factors of channel forms such as the sediment transport capacity depending notably on the size of the catchment and local conditions e g confinement riparian vegetation valley floor slope the rivers in new caledonia offer an interesting field laboratory to isolate the morphological effect of contrasted sediment supply conditions some of these rivers are known to be highly impacted by the coarse sediment waves induced by the mining of nickel deposits that started in the early 1870s which was particularly intensive between the 1940s and 1970s the propagation of the sediment pulses from the mining sites can be traced by the presence of wide and aggraded active channels along the stream network of nickel rich peridotite massifs a first set of 63 undisturbed catchments in peridotite massifs distributed across the grande terre was used to fit a classic scaling law between active channel width and drainage area a second set of 86 impacted sites where the presence of sediment waves was clearly attested by recent aerial imagery showed systematically wider active channels with a width ratio around 5 established from the intercept ratio of width area power laws more importantly this second set of disturbed sites confirmed that the residual of active channel widths computed from the scaling law of undisturbed sites is statistically positively related to the catchment scale relative area of major mining sediment sources it is therefore confirmed that the characterization of sediment supply conditions is crucial for the understanding of spatial patterns of active channel width and this should be more thoroughly considered in morphological studies of rivers draining environments with contrasted geomorphic activities on hillslopes

strong coherence between solar variability and the monsoon in oman between 9 and 6 kyr ago variations in the amount of solar radiation reaching the earth are thought to influence climate but the extent of this influence on timescales of millennia to decades is unclear a number of climate records show correlations between solar cycles and climate1 but the absolute changes in solar intensity over the range of decades to millennia are small2 and the influence of solar flux on climate is not well established the formation of stalagmites in northern oman has recorded past northward shifts of the intertropical convergence zone3 whose northward migration stops near the southern shoreline of arabia in the present climate4 here we present a high resolution record of oxygen isotope variations for the period from 9 6 to 6 1 kyr before present in a th u dated stalagmite from oman the 18o record from the stalagmite which serves as a proxy for variations in the tropical circulation and monsoon rainfall allows us to make a direct comparison of the 18o record with the 14c record from tree rings5 which largely reflects changes in solar activity6 7 the excellent correlation between the two records suggests that one of the primary controls on centennial to decadal scale changes in tropical rainfall and monsoon intensity during this time are variations in solar radiation

the role of crystallized magma and crustal fluids in intraplate seismic activity in talala region saurashtra western india an insight from local earthquake tomography abstract the talala region in saurashtra western india is one of the seismically active intraplate regions on the earth in recent past this region has been site of moderate magnitude earthquakes as well as swarm type earthquake activities to understand the processes of earthquake generation in this intraplate setting we constrained the earthquake distribution pattern along with the crustal seismic p wave velocity vp and vp vs variations using local earthquakes data we inverted 2470 p and 2230 s wave arrival times from 550 earthquakes which were recorded over 11 seismic stations during 2007 to 2012 the earthquakes distribution shows that the seismicity is following nne ssw trend extending for a distance of 25 km and up to 15 km in depth the seismic tomographic images show that the swarm type earthquake activities at shallower depths are mostly in the zone of lower vp and lower vp vs whereas the moderate magnitude earthquakes are occurring in a nw trending zone of higher vp and higher vp vs possibly indicating a zone of crystallized mafic magma which was transported from deeper earth this zone represents a pronounced heterogeneity and provides locale for stress accumulation in this region after 2001 bhuj earthquake mw 7 7 due to stress perturbation the nne ssw trending fault got activated and caused bigger earthquakes in this region moreover the crystallized mafic magma is possibly feeding fluids at shallower depths for causing the swarm type earthquake activities in this region

the 1996 biescas campsite disaster in the central spanish pyrenees and its temporal and spatial context on the evening of the 7 august 1996 an intense storm occurred over the aras catchment near biescas in the central pyrenees eighty seven people were killed as a result of the subsequent flood which hit a campsite located on the alluvial fan at the outlet of the 18 8 km2 catchment this paper presents the main results of a hydromorphological study of the event the betes subcatchment received the most intense rainfall estimated at somewhat in excess of 250 mm which resulted in a peak flow from this tributary of 300 m3 s 1 just downstream from the betes river junction flow in the main channel reached 400 m3 s 1 increasing to around 500 m3 s 1 further downstream rainfall in the larger aso tributary was less intense and in the head reaches flow remained within bank representing a one in two year return period event flow from this tributary did not exceed 100 m3 s 1 indicating that the betes subcatchment supplied some 75 of the flow from just 28 7 of the catchment area the extreme flows caused the collapse of a series of sediment trap dams in the aras channel downstream of the betes junction this resulted in the addition of 68 000 m3 of sediment to an already disastrous event data from other rain gauges in the area showed both the extremely local nature of the event and the problems of return period analysis for such storms whose peaks are rarely observed at gauges together with the high geomorphological risks of the zone this leads to the conclusion that a new method of spatial and temporal risk analysis is required for infrastructure planning 1997 john wiley sons ltd

an integrated approach for investigating geomorphic response to extreme events methodological framework and application to the october 2011 flood in the magra river catchment italy a high magnitude flash flood which took place on 25 october 2011 in the magra river catchment 1717 km2 central northern italy is used to illustrate some aspects of the geomorphic response to the flood an overall methodological framework is described for using interlinked observations and analyses of the geomorphic impacts of an extreme event the following methods and analyses were carried out i hydrological and hydraulic analysis of the event ii sediment delivery by event landslide mapping iii identification and estimation of wood recruitment deposition and budgeting iv interpretation of morphological processes by analysing fluvial deposits v remote sensing and geographic information system gis analysis of channel width changes in response to the high magnitude hydrological event a large number of landslides occurred consisting of earth flows soil slips and translational slides and a large quantity of wood was recruited in most part deriving from floodplain erosion caused by bank retreat and channel widening the most important impact of the flood event within the valley floor was an impressive widening of the overall channel bed and the reactivation of wide portions of the pre event floodplain along the investigated unconfined or partly confined streams total investigated length of 93 5 km the channel width after the flood was up to about 20 times the channel width before the event the study has shown that a synergic use of different methods and types of evidence provides fundamental information for characterizing and understanding the geomorphic effects of intense flood events the prediction of geomorphic response to a flood event is still challenging and many limitations exist however a robust geomorphological analysis can contribute to the identification of the most critical reaches copyright 2016 john wiley sons ltd

an insight into the unrest phenomena at the campi flegrei caldera from vp and vp vs tomography high resolution vp and vp vs tomography of the campi flegrei caldera is obtained using active and passive seismic data we find a continuous ring of high vp anomaly that defines the caldera rim associated to the last collapse a sharp vp vs decrease is observed between 2 and 4 km depth suggesting the absence of magmatic fluids and the presence of rock volumes with over pressured gas within the source region of uplift atmospheric water penetrating within the caldera and deep co2 fluids are presumably heated by a magmatic body located at depth greater than 4 km nested within the limestone layer along the fractures bordering the shallow high vp rim deep gas and co2 fluids up raise and are released in the pozzuoli solfatara we hypothesize that the past unrest episode is more likely due to pressure changes within the shallow geothermal reservoir located at the top of the magma intrusion

the impact of recent climate change on flooding and sediment supply within a mediterranean mountain catchment southwestern crete greece maas g s macklin m g 2002 the impact of recent climate change on flooding and sediment supply within a mediterranean mountain catchment southwestern crete greece earth surface processes and landforms 27 10 1087 1105

biogenic flux of al to sediment in the central equatorial pacific ocean evidence for increased productivity during glacial periods we examined the flux of al to sediment accumulating beneath the zone of elevated productivity in the central equatorial pacific ocean along a surface sediment transect at 135 w as well as downcore for a 650 kyr record at 1 3 n 133 6 w across the surface transect a pronounced broadly equatorially symmetric increase in al accumulation is observed relative to ti with al ti ratios reaching values 3 4 times that of potential detrital sources the profile parallels biogenic accumulation and the modeled flux of particulate 234th suggesting rapid and preferential adsorptive removal of al from seawater by settling biogenic particles normative calculations confirm that most al is unsupported by the terrigenous fraction the observed distributions are consistent with previous observations of the relative and absolute behavior of al and ti in seawater and we can construct a reasonable mass balance between the amount of seawater sourced al retained in the sediment and the amount of seawater al available in the overlying column the close tie between al ti and biogenic accumulation as opposed to concentration emphasizes that biogenic sedimentary al ti responds to removal transport phenomena and not bulk sediment composition thus in these sediments dominated by the biogenic component the bulk al ti ratio reflects biogenic particle flux and by extension productivity of the overlying seawater the downcore profile of al ti at 1 3 n displays marked increases during glacial episodes similar to that observed across the surface transect from a background value near al ti of average upper crust the excursions in al ti are stratigraphically coincident with maxima in both bulk and caco3 accumulation and the excess al appears to not be preferentially affiliated with opaline or organic phases consistent with the similar behavioral removal of al and 234th the latter of which responds to the total particle flux the al flux reflects carbonate accumulation only because carbonate comprises the dominant flux in these particular deposits these results collectively indicate that 1 al in biogenic sediment and settling biogenic particles is strongly affected by a component adsorbed from seawater therefore the common tenet that al is dominantly associated with terrestrial particulate matter and the subsequent use of al distributions to calculate the abundance and flux of terrestrial material in settling particles and sediment needs to be reevaluated 2 the al ti ratio in biogenic sediment can be used to trace the productivity of the overlying water providing a powerful new paleochemical tool to investigate oceanic response to climatic variation 3 the close correlation between the al ti productivity signal and carbonate maxima downcore at 1 3 n suggests that the sedimentary carbonate maxima in the central equatorial pacific ocean record increased productivity during glacial episodes

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

solar forcing of centennial scale east asian winter monsoon variability in the mid to late holocene abstract centennial scale variability of the east asian winter monsoon during the holocene is poorly understood because suitable archives and proxies are lacking here we present a high resolution 30 yr spacing planktonic foraminiferal o 18 record of neogloboquadrina incompta dextral form which reflects sea surface temperature during the winter season for the last 6000 yrs from marine sediments in the western north pacific stronger winter monsoons indicated by cooler winter ssts correspond to weaker summer monsoons indicated by the cave oxygen isotopes in centennial scale variability the variability also shows good correlation with o 18 records in lake sediments and ice cores from the yukon territory canada spanning the last 4500 yrs suggesting east west climate coupling across the north pacific furthermore the climate changes across the north pacific co vary over widespread regions such as the eastern tropical pacific and the northern red sea and the reconstructed solar activity the cross spectral and wavelet analyses show that the east asian winter monsoon shares some cyclicity with the solar variability our results suggest that the solar activity is a fundamental forcing producing the centennial scale eawm variability mediated by the large scale climate linkages

driving magma to the surface the 2011 2012 el hierro volcanic eruption we reanalyzed the seismic and deformation data corresponding to the pre eruptive unrest on el hierro canary islands in 2011 we considered new information about the internal structure of the island we updated the seismic catalogue to estimate the full evolution of the released seismic energy and demonstrate the importance of non located earthquakes using seismic data and gps displacements we characterized the shear tensile type of the predominant fracturing and modelled the strain and stress fields for different time periods this enabled us to identify a prolonged first phase characterized by hydraulic tensile fracturing which we interpret as being related to the emplacement of new magma below the volcanic edifice on el hierro this was followed by post injection unidirectional migration probably controlled by the stress field and the distribution of the structural discontinuities we identified the effects of energetic magmatic pulses occurring a few days before the eruption that induced shear seismicity on pre existing faults within the volcano and raised the coulomb stress over the whole crust we suggest that these magmatic pulses reflect the crossing of the moho discontinuity as well as changes in the path geometry of the dyke migration towards the surface the final phase involved magma ascent through a pre fractured crust

the variation of summer monsoon precipitation in central china since the last deglaciation abstract two stalagmites c996 1 and c996 2 collected from the jiuxian cave in the shaanxi province in central china have been studied with u series dating and stable isotope analysis thirty eight 230 th dating results showed that the stalagmite c996 1 was continuously deposited through the last 8 5 ka bp thousand years before present present 1950 ad and c996 2 was deposited through the last 19 ka bp excluding two growth hiatuses between 8 3 and 5 7 ka bp and 15 4 and 11 9 ka bp with a relatively stable boundary condition we interpret the 18 o of speleothem calcite as most indicative of the amount of summer monsoon precipitation although temperature and other factors might have some minor impact the 18 o records show notable changes within the last glacial maximum lgm resembling other east asian monsoon records such as those from the hulu and sanbao caves suggesting that significant monsoonal climate changes occurred in eastern asia as far north as the qinling mountains during the lgm interval a comparison of our records to precisely dated contemporaneous speleothem records from other caves shows that the increasing trend of 18 o during the holocene commenced as early as 7 5 ka bp in the low latitude monsoonal area i e the hoti cave while at higher latitudes this shift occurred later such as 7 0 ka bp in the dongge cave 5 3 ka bp in the heshang cave 4 7 ka bp in the sanbao cave and 4 5 ka bp in the jiuxian cave these results imply an asynchronous change of the summer monsoon precipitation occurred in east asia during the holocene the asynchrony may be related to the responses of a coupled tropical and subtropical monsoon system to changes of the insolation and the differences in thermal forcing which result from the complex geographical configuration the variation of sea surface temperature sst in the western tropical pacific may also have important impacts on the summer monsoon precipitation changes in central and northern china because it affects the northwestern pacific subtropical high a monsoon front regulator more robust tests are needed to confirm this phenomenon and to evaluate the contribution of different factors in detail

v s of the uppermost crust structure of the campi flegrei caldera southern italy from ambient noise rayleigh wave analysis abstract shear wave velocities v s are defined in the uppermost 1 2 km of the campi flegrei caldera through the non linear inversion of the group velocity dispersion curves of fundamental mode rayleigh waves extracted from ambient noise cross correlations between two receivers noise recordings three months long at 12 seismic stations are cross correlated between all couples of stations the experiment provided successful results along 54 paths inter stations distance of which 27 sampled a depth 1 km v s contour lines are drawn from 0 06 km b s l to 1 km depth b s l and show difference between the offshore gulf of pozzuoli and coastline and the onshore areas at 0 06 km b s l the gulf of pozzuoli and the coastline are characterized by v s of 0 3 0 5 km s and of 0 5 0 7 km s respectively such velocities are typical of neapolitan pyroclastic soils and fractured or altered tuffs the inland shows v s in the range 0 7 0 9 km s typical of neapolitan compact tuffs velocities increase with depth and at 1 km depth b s l velocities lower than 1 5 km s are still present in the gulf and along the coastline while velocities higher than 1 9 km s characterize the eastern sector grossly coincident with the neapolitan yellow tuff caldera rim the s vito plain and the area between solfatara and sw of astroni such features are much more evident along two cross sections drawn in the offshore and onshore sectors by integrating our v s models with literature data our models join previous noise cross correlation studies at greater scale at depths of 0 7 0 8 km hence the picture of the campi flegrei caldera is shown up to a depth of 15 km v s of about 1 7 km s corresponding to compression velocities v p of about 3 km s computed by using the v p v s ratio resulted in the inversion are found at depths of 1 1 km in the centre of the gulf of pozzuoli and at a depth of about 0 7 km b s l onshore an increment of v s velocity 1 9 2 0 km s is locally observed onshore which might be attributed to a layer of tuffs and tuffites interbedded with thin lava beds according to the correlation of v s with stratigraphies in the deep drillings of s vito

impact of a large flood on mountain river habitats channel morphology and valley infrastructure abstract the biala river polish carpathians was considerably modified by channelization and channel incision in the twentieth century to restore the biala establishing an erodible corridor was proposed in two river sections located in its mountain and foothill course in these sections longer unmanaged channel reaches alternate with short channelized reaches and channel narrowing and incision increases in the downstream direction in june 2010 an 80 year flood occurred on the river and this study aims at determining its effects on physical habitat conditions for river biota channel morphology and valley floor infrastructure surveys of 10 pairs of closely located unmanaged and channelized cross sections performed in 2009 and in the late summer 2010 allowed us to assess the flood induced changes to physical habitat conditions a comparison of channel planforms determined before 2009 and after 2012 the flood provided information on the degree of channel widening as well as changes in the width of particular elements of the river s active zone in eight stretches of the biala the impact of the flood on valley floor infrastructure was confronted with the degree of river widening in unmanaged and channelized river reaches before the flood unmanaged cross sections were typified by finer bed material and greater lateral variability in depth averaged and near bed flow velocity than channelized cross sections the flood tended to equalize habitat conditions in both types of river cross sections obliterating differences in particular physical habitat parameters between channelized and unmanaged channel reaches river widening mostly reflected an increase in the area of channel bars whereas the widening of low flow channels was less pronounced a comparison of channel planform from 2009 and 2012 indicated that intense channel incision typical of downstream sections limited river widening by the flood active channel width increased by half in the unmanaged cross sections and by one third in the channelized cross sections however damage to the valley floor infrastructure was practically limited to the channelized river reaches with reinforced channel banks this indicates incompetent management of riparian areas rather than the degree of river widening as a principal reason for the economic losses during the flood

causes of 20th century channel narrowing in mountain and piedmont rivers of southeastern france extensive channel narrowing in southeastern france provides an illustration of geomorphic response to land use changes the study region comprises a range of environments from large piedmont and intramountain gravel bed rivers to small mountain streams field measurements and analysis of historical data demonstrate two distinct periods of channel change from 1850 to 1950 channel narrowing is interpreted to be the result of a recovery process in response to widespread channel destabilization induced by major floods during the second half of the 19th century at the time the largely deforested basins were highly responsive to flooding whereas the recovery process was accelerated by floodplain and basin scale land use changes afforestation and torrential control works which in turn reduced sediment delivery and enabled vegetation development in channels from 1950 to 1970 channel narrowing accelerated in most of the studied rivers this recent phenomenon is considered as a human induced fluvial adjustment directly related to forest development on river margins and human abandonment of intensive floodplain land uses at the same time long profile degradation occurred as a result of long term bedload supply decrease in small mountain streams channel narrowing is mainly explained by channel incision which seems to progress from upstream where sediment sources are progressively stabilized by afforestation copyright 2002 john wiley sons ltd

geochemical evidences of magma dynamics at campi flegrei italy abstract campi flegrei caldera within the neapolitan area of italy is potentially one of the most dangerous volcanoes in the world and during the last decade it has shown clear signs of reactivation marked by the onset of uplift and changes in the geochemistry of gas emissions we describe a 30 year long data set of the co2 he ar n2 compositions of fumarolic emissions from la solfatara crater which is located in the center of the caldera the data display continuous decreases in both the n2 he and n2 co2 ratios since 1985 paralleled by an increase in he co2 these variations cannot be explained by either processes of boiling condensation in the local hydrothermal system or with changes in the mixing proportions between a magmatic vapor and hydrothermal fluids we applied the magma degassing model of nuccio and paonita 2001 earth planet sci lett 193 467 481 using the most recent inert gas solubilities in order to interpret these peculiar features in accordance with petrologic constraints derived from the ranges of the melt compositions and reservoir pressures at campi flegrei the model simulations for mafic melts trachybasalt and shoshonite show a remarkably good agreement with the measured data both decompressive degassing of an ascending magma and mixing between magmatic fluids exsolved at various levels along the ascent path can explain the long term geochemical changes recalling that i a sill like reservoir of gases at a depth of 3 4 km seems to be the main source of ground inflation and ii there is petrologic and geophysical evidence for a reservoir of magma at about 8 km below campi flegrei we suggest that the most intense episodes of inflation occur when the gas supply to the sill like reservoir comes from the 8 km deep magma although fluids exsolved by magma bodies at shallower depths also contribute to the gas budget our work highlights that in caldera systems where the presence of hydrothermal aquifers commonly masks the magmatic signature of reactive volatiles inert gases are the preferred species to use when seeking information on the melt composition dynamics and structure of the plumbing systems

time dependent co2 variations in lake albano associated with seismic activity lake albano alban hills volcanic complex central italy is located in a densely populated area near rome the deep lake waters have significant dissolved co2 concentrations probably related to sub lacustrine fluid discharges fed by a pressurized co2 rich reservoir the analytical results of geochemical surveys carried out in 1989 2010 highlight the episodes of co2 removal from the lake the total mass of dissolved co2 decreased from 5 8 107 kg in 1989 to 0 5 107 kg in 2010 following an exponential decreasing trend calculated values of both dissolved inorganic carbon and co2 concentrations along the vertical profile of the lake indicate that this decrease is caused by co2 release from the epilimnion at depth 9 m combined with 1 water circulation at depth 95 m and 2 co2 diffusion from the deeper lake layers according to this model lake albano was affected by a large co2 input that coincided with the last important seismic swarm at alban hills in 1989 suggesting an intimate relationship between the addition of deep originated co2 to the lake and seismic activity in the case of a co2 degassing event of an order of magnitude larger than the one that occurred in 1989 the deepest part of lake albano would become co2 saturated resulting in conditions compatible with the occurrence of a gas outburst these results reinforce the idea that a sudden co2 input into the lake may cause the release of a dense gas cloud presently representing the major volcanic threat for this densely populated area

modern climate forcing of terrigenous deposition in the tropics cariaco basin venezuela one approach to deciphering tropical quaternary paleoclimate records has been to study the composition of terrigenous material in order to infer past changes in hydrologic and atmospheric conditions here we present the inorganic geochemistry major and trace elements of modern sediment traps and shelf sediments in the tropical cariaco basin venezuela in order to characterize seasonal variation in deposition of the terrigenous component and to document linkages within the ocean atmosphere climate system we show that variation in the chemistry of terrigenous input to the basin is a sensitive monitor of the annual meridional migration of the intertropical convergence zone itcz additionally seasonal terrigenous relative abundances are decoupled from terrigenous absolute fluxes showing that abundances are not directly related to terrigenous delivery changes in mixing between local fluvial sediments fluvial and or eolian mafic material and saharan dust explains the observed seasonality the modern seasonal variations are significantly smaller than those observed in the glacial interglacial paleorecord indicating that climate sensitivity at the two time scales is very different a striking contrast in the behavior of ti al between the longer glacial interglacial time scale and the modern seasonality also suggests that long term terrigenous deposition is not linked simply to 100kyr shifting of the itcz the modern data can be reconciled with the glacial interglacial record by invoking generally drier conditions during glacial periods over tropical latitudes combined with intermittent wet conditions caused by precessional forcing 2007 elsevier b v all rights reserved

combining multi physical measurements to quantify bedload transport and morphodynamics interactions in an alpine braiding river reach abstract understanding the interactions between bedload transport and morpholdynamics in braided streams has important applications in river management and restoration direct field measurements addressing this question are however scarce as they are often challenging to perform here we report an extensive two month field campaign in an alpine braided reach la severaisse river french alps that experienced predictable daily peak discharge 48 events observed generating significant bedload transport and morphological changes during the melting season we monitored these processes using a wide range of direct and indirect techniques bedload sampling continuous seismic measurements pebbles tracking topographic surveys remote sensing using ground control cameras and drone flights doing so surrogate measurements allowed to extend temporally discrete manual bedload sampling and to extend spatially local riverbed cross section measurements these measurements provide unique complementary constraints on the targeted physics at various spatial and temporal scales which enabled us to draw robust conclusions data showed a progressive decrease in bedload transport for a given flow rate along the two months period simultaneously river morphology in the braided sections changed from an incised to a more distributed configuration which led to a decrease of local maxima in dimensionless shear stresses in the braided reach for similar flow conditions this control of bedload transport by maximum local shear stresses was in line with tracked pebble surveys indicating that coarse bedload particles were mostly transported in the main active channel at the reach scale this transport was found to be more efficient in laterally confined sections than in braided ones which has important implications in terms of bedload estimation in alternative confined and braided unconfined rivers finally this study highlight the interest to combine a large variety of traditional and innovative measurements techniques to better understand complex sediment transport processes in the field

solar forcing induced spatial synchronisation of the east asian summer monsoon on centennial timescales abstract spatial patterns in centennial scale variations of the east asian summer monsoon easm during the holocene are poorly constrained due to the lack of high resolution records with detailed chronologies especially in southern china here we present high resolution 35 yr proxy records spanning the last 7500 years from a well dated sediment core yj core from the northern inner shelf of the south china sea al ti and fe variations were employed as indicators of terrigenous influx and k al ratios were used as a tracer of chemical weathering to document variations in the intensity of the easm the results show a series of centennial scale weak easm events which are generally synchronous with those inferred from other geologic archives from monsoonal regions in the eastern and southern china moreover these events are synchronous with periods of weak solar activity and the spectral analysis demonstrates that the easm and solar activity share some general cyclicity patterns we therefore suggest that solar activity is a fundamental driving force for the spatial synchronisation of the easm on centennial timescales across the monsoon region

terrigenous input and paleoproductivity in the southern ocean the geochemistry of several sites along the polar front zone of the southern ocean revealed significant changes in terrigenous input and productivity on glacial timescales our records indicate concentrations and fluxes of terrigenous elements i e fe al and ti are low during interglacials and increase tenfold to twentyfold during glacials phosphorus accumulation reactive p concentrations and p ti ratios exhibit similar trends as the terrigenous components suggesting increased export production during glacials in all cores elemental ratios remain relatively constant indicating terrigenous sources at each site have not likely varied over the past 250 kyr iron accumulation rates for these sites are 10 times higher during glacials than interglacials and exceed the estimated regional eolian fluxes by 50 times the source of this terrigenous material is thus likely to be hemipelagic rather than direct eolian input or ice rafting and we speculate fe upwelled from this source may have stimulated glacial productivity in the southern ocean

geomorphic diversity in the braided wandering bela river slovak carpathians as a response to flood variability and environmental changes abstract changes in the morphological pattern of the gravel bed bela river slovak carpathians were investigated to infer about the impact of flood events and environmental changes on the evolutionary trend of the river since the mid twentieth century the post flood period serial geomorphic analysis popsega approach coupled with gis analysis was used to identify morphological changes that occurred during particular flood periods the study focused on assessing how six flood periods fp with differing flood characteristics have influenced the evolutionary trend of the river several sets of aerial photos 1949 1961 1973 1986 1992 2003 2009 taken after the periods with the occurrence or lack of major floods provided data about channel landform changes in 227 river segments of 100 m length a decreasing trend of the area of the river s active zone from 2 5 km2 in 1949 to 1 4 km2 in 2009 was identified the first fp 1949 1961 with a very high magnitude flood in 1958 ri50 was characterized by increasing total channel length island number area and the number density of confluence diffluence pairs nodes and by decreasing bar area during this fp the frequency of cores of channel dynamics as well as the shannon s index of landforms diversity reached the highest values the following fp 1962 1973 with four 5 to 10 year floods exhibited the inverse pattern of changes in channel form parameters although the core frequency of channel dynamics and shannon s diversity index were still high the river system seems to have been relatively stable between 1974 and 1986 third fp with some decrease in the area of channel forms and in pattern metrics values during the fourth fp 1987 1992 several 1 5 to 3 year floods occurred and were associated with a decrease in some channel forms and a further decrease of the pattern metrics values an increase in all analysed channel parameters especially bar area and pattern metrics values occurred in the years 1993 2002 fifth fp as a consequence of two floods of moderate magnitude in 1997 ri7 and 2001 ri3 5 the lowest values of bar area and pattern metrics during the whole study period were recorded during the last fp 2002 2008 whereas island area increased at that time the study shows that the occurrence of floods during the last six decades has not returned the bela to its former state because of the overall decrease in flood magnitudes changes in catchment sediment supply induced by the increasing forest cover in the catchment from 22 7 in 1957 to 34 8 in 2008 and changes in channel boundary conditions channelization channel incision small hydropower plant constructions

shear wave splitting vp vs and gps during a time of enhanced activity at aso caldera kyushu 1 we performed shear wave splitting analyses and calculated vp vs ratios on local earthquakes recorded at seven stations around aso volcano japan between 2001 and 2008 the mean vp vs of 1 61 0 01 from all stations is among the lowest average values found anywhere in the world a temporal change of shear wave splitting fast polarization is observed at one station additionally spatial variations of shear wave splitting delay times and vp vs ratios show a correlation at three stations we suggest that stress controlled anisotropy dominates at these stations gps baselines and 2d strain reveal extension in the caldera in 2003 and compression before and after 2003 strain shortening axes indicate either a variation in regional stress or a local stress source that overprints the regional field in 2003 baseline changes correlate with periods of increased low frequency seismic activity located deeper than 15 km compaction and degassing of a previously reported sill at approximately 15 km depth could lead to constantly high pressure of volcanic gases over a wide area and explain the generally low vp vs ratios and the observed compression in the caldera we propose that a small volume of magma intruded into the sill in 2003 caused extension at the surface and triggered ash eruptions between 2003 and 2005 associated localized migration of gases in overpressured cracks with aspect ratios potentially 0 5 in the upper crust with porosities 0 1 could be the source of changes in seismic anisotropy and explain the slight variations observed in vp vs

paleohydraulic reconstruction of flash flood peaks from boulder deposits in the colorado front range nine watersheds in the colorado front range with steep bedrock channels were used to test the accuracy of paleohydraulic reconstruction of large flash floods using boulder deposits the nine basins consist of eight small ungauged basins ranging in size from 1 6 to 29 km2 and the big thompson river at the mouth of the big thompson canyon draining 790 km2 between 1923 and 1976 all nine basins had had one catastrophic flash flood the magnitude of which has been estimated by the conventional slope area method in each basin coarse boulder deposits of the large flash floods were identified and three axes of the five largest boulders were measured along with at least two profiles of the valley cross section a simple arithmetic average of two theoretical and two empirical relationships was used to estimate average flood velocity using boulder size and shape average depth was estimated as the arithmetic average of four values computed from the manning equation a regression equation for boulder size and unit stream power a relative smoothness equation and a modified shields relationship the appropriate flood width for the estimated average depth was found by iteration using the valley cross sections the paleohydraulic discharges thus computed generally underestimate conventional slope area discharge estimates on small streams by as much as 75 although the average amount is only 28 too low and the reconstructed discharge in one stream was 31 too large the big thompson river flood of 1976 was overestimated by 76 reasons for discrepancy in reconstructed peaks could include 1 the possibility that floods may have been able to move boulders larger than those available to be moved 2 overestimation of the slope area discharge because high water marks were set prior to erosion of the channel 3 underestimation of original roughness coefficients and 4 macroturbulent effects during fast deep flows the paleohydraulic technique is applied to two other streams in colorado with sedimentological evidence of large flash floods but no conventional indirect discharge estimates a small tributary to the big thompson river draining 1 8 km2 has a paleohydraulic reconstructed flood peak of about 60 m3 s from a flood in 1976 using boulders excavated from a foundation site in holocene alluvium along boulder creek in boulder colorado a paleohydraulic reconstructed flood peak of between 860 and 1 512 m3 s is calculated this is 1 4 to 2 4 times the magnitude of the estimated 500 yr flood

spatio temporal patterns of channel changes in response to a major flood event the case of the magra river central northern italy on october 25th 2011 the magra river central northern italy was affected by a significant flood event with an estimated return interval ranging from 30 to 200 years this study investigates the morphological responses of the magra river to this major flood event with the aims of i documenting the channel changes which occurred in response to the flood ii analysing this response within the context of the historical trend of width changes iii investigating the possible factors controlling the spatial pattern and the intensity of the observed changes significant channel widening was documented along the entire length studied about 34 km ranging from 3 to 90 of the pre flood channel width braided reaches were characterized by the most severe planimetric changes although characterized by high rates of change these variations are however amply included in the historical range of channel width variability over approximately the last 150 years from 1877 to present day and are comparable with though generally lower than the channel width of the 1950s statistical analyses simple and multiple regressions between the observed changes in channel width and a series of selected morphological and hydraulic controlling factors showed no robust correlations to explain the spatial pattern and the variability of channel adjustments instead major adjustments occurred along reaches characterized by the confluence of those streams draining the sub catchments where the storm was concentrated copyright 2014 john wiley sons ltd

variability in the mean latitude of the atlantic intertropical convergence zone as recorded by riverine input of sediments to the cariaco basin venezuela abstract changes in the strength and position of the intertropical convergence zone itcz are an important component of climate variability in the tropical atlantic the cariaco basin located on the northern margin of venezuela is sensitive to tropical atlantic climate change and its sediments provide a record of past itcz behavior today the cariaco basin experiences two distinct seasons that reflect the annual migration of the atlantic itcz between january and march when the itcz lies south of the equator northeasterly trade winds sit directly over cariaco basin and strong coastal upwelling and dry conditions dominate beginning in june july as the itcz moves north local rainfall reaches a maximum and the upwelling diminishes or disappears here we summarize new and previously published data on the river derived terrigenous fraction of cariaco basin sediments as well as comparisons to other paleoclimate records which together suggest a coherent climatologic response in the tropical atlantic triggered by a pattern of itcz migration that mimics the seasonal cycle during periods of cooler north atlantic ssts on time scales ranging from the little ice age to the younger dryas to the cold stadials of the last glacial decreased detrital delivery to cariaco basin from local rivers suggests a southward shift in the mean latitudinal position of the itcz during warm interstadials and periods of holocene and deglacial warmth northward shifts in itcz position and its belt of convective rainfall are inferred from increased detrital delivery to the basin whether the rapid shifts in itcz position and precipitation recorded by cariaco basin sediments and other regional records reflect a response to forcing originating in the high latitude atlantic or to forcing potentially sourced in the tropics is a key question yet to be fully answered

recent ground movement and seismic activity in campi flegrei southern italy episodic growth of a resurgent dome leveling surveys in campi flegrei an active volcanic caldera in southern italy show that this caldera has undergone both subsidence and uplift of a few meters during the past 85 years a single source located at a depth of about 3 km beneath the center of the caldera can account for almost all elevation changes recorded in campi flegrei since the first leveling survey conducted in 1905 1907 this includes leveling surveys that span periods of subsidence such as between 1905 1907 and 1919 and between january 1985 and october 1986 and periods of rapid uplift between march 1970 and october 1971 and between january 1981 and december 1984 a possible geometry for the source of uplift and subsidence beneath campi flegrei is a rectangular horizontal sheet located at a depth of about 3 km and centered a few hundred meters east of the city of pozzuoli the horizontal dimensions of this sheet are about 1 5 km by 3 0 km the long axis is oriented n70 w this sheet lies adjacent to the most intense area of seismicity that occurred from mid 1983 to december 1984 during an uplift episode this sheet may represent the top of a magma body undergoing internal pressure changes possibly by intrusion of additional magma subsidence is caused by groundwater removal from the water saturated deposits that fill this caldera to a depth of a few kilometers a temporary increase in subsidence rate after an uplift episode is caused by increased rate of groundwater removal from newly fractured regions that lie immediately above the magma body the close proximity of this water saturated region and the magma body makes it impossible to separate the depth to these two sources from the results of leveling surveys two observations indicate that uplift has occurred in the center of campi flegrei for at least the past several thousand years first marine deposits in the center of campi flegrei were uplifted at least 40 m between 4000 and 8000 years ago second continuous seismic profiles of the undersea portion of campi flegrei have identified only one region where rocks are fractured and faulted adjacent to the uplifted marine deposits that surround the point of maximum uplift indicated by recent leveling surveys on the basis of these observations and the historical record of activity we suggest that campi flegrei caldera is in a stage of growing a resurgent dome the present diameter of the resurgent dome is about 4 km and the maximum amount of vertical uplift during the past 10 000 years has probably not exceeded 100 m the episodes of rapid uplift and shallow earthquake swarms during the past 20 years are probably related to the growth of this resurgent dome

holocene cyclic climatic variations and the role of the pacific ocean as recorded in varved sediments from northeastern china we present an n alkane and compound specific carbon isotope record of the past 9 ka from the annually laminated sedimentary sequence of lake xiaolongwan northeastern china the n alkane distribution suggests that lake xiaolongwan has undergone a shift from an oligotrophic state with low algal production and little emergent submerged macrophytes in the early holocene to a eutrophic state with high algal production and abundant emergent submerged macrophytes since the middle holocene the pattern of variation observed in the biomarker proxies acl the n alkane average chain length paq aquatic macrophyte versus aquatic macrophyte and terrestrial plant ratio and lptp lake productivity terrigenous organic production is throughout the record similar to that of the total organic carbon the variation of compound specific carbon isotopic values in the middle and short chain alkanes was mainly regulated by lake productivity and the accumulating organic pool through time in this forested region where the vegetation is dominated by c 3 plants the long chain n alkanes c27ec31 are predominantly derived from leaf wax lipids the compound specific d 13 c27e31 value is sensitive to effective precipitation and therefore represents a useful indicator of regional monsoonal precipitation spectral analysis on the d 13 c27e31 time series reveals significant periodicities of 87e89 205e212 1020e1050 and 1750e2041 years on the centennial timescale the quasi periodicities around 88 and 210 years suggest a strong link between solar activity and monsoon rainfall the millennial monsoon cycle in northeastern china is associated with sea surface temperature sst variations in two active centers of the summer monsoon the western pacific subtropical high wpsh and the okhotsk high increasing sst in the subtropical sea may cause a northwards shift of the wpsh which extends the monsoon rain band meiyu to northeastern china and thus increasing rainfall in that region meanwhile decreasing sst in the okhotsk sea may strengthen the okhotsk high bringing more moisture into northeastern china we suggest that the pacific ocean is a main regulator for summer monsoon rainfall in northeastern china at present and at different time scales during the holocene

seismic images and rock properties of the very shallow structure of campi flegrei caldera southern italy in september 2001 an extensive active seismic investigation serapis experiment was carried out in the gulfs of naples and pozzuoli with the aim of investigating and reconstructing the shallow crustal structure of the campi flegrei caldera and possibly identifying its feeding system at depth the present study provides a joint analysis of the very shallow seismic reflection data and tomographic images based on the serapis dataset this is achieved by reflection seismic sections obtained by the 3d data gathering and through refined p velocity images of the shallowest layer of pozzuoli gulf z 3 500 m s correlates with units made up of agglomerate tuffs and interbedded lava which form the southern edge of the caldera which was probably formed following the two large ignimbritic eruptions that marked the evolutionary history of the area under study the upper part of the anomaly that tends to split into two parallel arcs is correlated with dikes volcanic mounds and hydrothermal alteration zones noted in previous shallow reflection seismic analyses the depth of the transition between the upper and lower parts of the anomaly is characterized by an abrupt vp increase on the one dimensional 1d profiles extracted from the 3d tomographic model and by the presence of a strong reflector located at about 0 6 0 7 s two way time twt on common mid point gathers the move out velocity analysis and stack of the p p and p s reflections at the layer bottom allowed to estimate relatively high vp vs values 3 7 0 9 this hypothesis has been tested by a theoretical rock physical modeling of the vp vs ratio as a function of porosity suggesting that the shallow layer is likely formed by incoherent water saturated volcanic and marine sediments that filled pozzuoli bay during the post caldera activity

overpressure detection from compressional and shear wave data by analyzing experimental data we show that in many room dry rocks the poisson s ratio pr decreases with decreasing differential pressure confining minus pore pressure this means that in gas saturated rocks pr decreases with increasing pore pressure we confirm the generality of the observed effect by theoretically reproducing it via effective medium modeling this effect can be used as a new tool for overpressure detection from surface seismic cross well sonic logs and measurements ahead of the drill bit

holocene monsoon climate documented by oxygen and carbon isotopes from lake sediments and peat bogs in china a review and synthesis there has been much recent debate about holocene climate variation in the monsoon region of china especially the temporal pattern of variations in precipitation the time transgressive nature of the holocene precipitation maximum and the extent to which variations in regions influenced by the indian summer monsoon ism and the east asian summer monsoon easm have been synchronous we summarize and compare carbonate oxygen isotope records delta o 18 carb from ten lakes within the present day ism region we discuss their paleoclimate significance considering the present day moisture source isotopic composition of precipitation and the hydrological setting the delta o 18 carb records are controlled mainly by the isotopic composition of lake water which in turn is a function of regional precipitation evaporation p e balance and the proportion of precipitation that is monsoon derived we normalized the delta o 18 carb data and used these records to generate an integrated moisture index this index along with oxygen isotope records from speleothems and carbon isotope records delta c 13 org from peats within the monsoon region suggests that holocene climate was broadly synchronous across the monsoon region and within the limits of accuracy of the existing age models provides no strong evidence for previously proposed anti phasing of the ism and the easm stable isotope records from lake sediments and peat bogs have excellent potential for providing high quality paleoclimate data for monsoon asia and complement high resolution speleothem sequences which are only found in certain localities c 2011 elsevier ltd all rights reserved

the p wave velocity structure of deception island antarctica from two dimensional seismic tomography abstract deception island is a volcanic island with a flooded caldera that has a complex geological setting in bransfield strait antarctica we use p wave arrivals recorded on land and seafloor seismometers from airgun shots within the caldera and around the island to invert for the p wave velocity structure along two orthogonal profiles the results show that there is a sharp increase in velocity to the north of the caldera which coincides with a regional normal fault that defines the northwestern boundary of the bransfield strait backarc basin there is a low velocity region beneath the caldera extending from the seafloor to 4 km depth with a maximum negative anomaly of 1 km s refracted arrivals are consistent with a 1 2 km thick layer of low velocity sediments and pyroclastites infilling the caldera synthetic inversions show that this layer accounts for only a small portion of the velocity anomaly implying that there is a significant region of low velocities at greater depths further synthetic inversions and melt fraction calculations are consistent with but do not require the presence of an extensive magma chamber beneath the caldera that extends downwards from 2 km depth

a three dimensional qp imaging of the shallowest subsurface of campi flegrei offshore caldera southern italy to improve the knowledge of the shallowest subsurface of campi flegrei caldera a 3 d p wave attenuation tomography of the area was performed we analyzed about 18 000 active seismic traces which provided a dataset of 11 873 t measurements e g the differential traveltimes to quality factor ratios these were inverted through an adapted tomographic inversion procedure the 3 d tomographic images reveal an average qp about 70 interpreted as water saturated volcanic and marine sediments an arc like low qp structure at 0 5 1 km depths was interpreted as a densely fractured fluid saturated rock volume well matching the buried rim of campi flegrei caldera the spatial distribution of high and low qp bodies in the inner caldera is correlated with low vp values and may reflect either the differences in the percentage of fluid saturation of sediments or the presence of vapor state fluids beneath fumaroles manifestations

temporal change of upper crustal vp vs ratios with volcanic evolution in redoubt volcano abstract volcanic activities accompany changes in the physical and chemical properties of the medium the ratio between p and s wave velocities v p v s is sensitive to the medium property changes we investigate temporal variations of the v p v s ratios in the upper crust around redoubt volcano in the 1989 2014 time period using the traveltimes of local earthquakes the v p v s ratios reached 2 0 immediately prior to the 1989 1990 and 2009 eruptions these high v p v s ratios may be associated with partial melts in the edifice the v p v s ratios rapidly decreased to 1 7 during the 1989 1990 and 2009 eruptions due to decreasing temperatures fluids and pore pressures and increasing effective stresses after melt eruptions and gas emission the change rates of the v p v s ratios showed evident spatial distributions the v p v s ratios increased at a rate of 0 025 0 003 yr 1 below the 2009 vent during the inter eruption period between the 1989 1990 and 2009 eruptions due to an increase in the temperature which may be associated with the recharge of the magma in the lower crust the increase rate of the v p v s ratios was as low as 0 005 0 001 yr 1 in the regions located away from the eruption site the v p v s ratios appear to have increased consistently at a rate of 0 017 0 004 yr 1 since the 2009 eruption

synchronous climate anomalies in the western north pacific and north atlantic regions during the last 14 000 years abstract a peat cellulose 18 o record spanning around 14 000 years from the hani peat mire in northeastern china reveals several abrupt temperature anomalies in the period from the last deglaciation through the holocene the timing of these anomalies coincides well with the notable cooling events recorded respectively using the gisp2 ice core and ice rafted sediment of the north atlantic ocean such as the older dryas inter allerod younger dryas and the nine ice rafted debris events the results demonstrate that this repeating pattern of abrupt temperature deterioration is not limited to the north atlantic area at high latitude but also exists in the western north pacific region at middle latitude the synchronous temperature anomalies possibly are resulted from the joint effects of meltwater discharge into the north atlantic ocean and reduced solar activity in the period from around 8600 to 8200 cal yrs bp the hani peat record shows a broad 18 o peak that may reflect compound climate signals resulting from the two kinds of forcing factors the temperature drop related to reduced solar activity at around 8600 8250 cal yrs bp and the temperature anomaly attributed to the meltwater effect at around 8220 70 cal yrs bp this result may provide palaeo temperature evidence for existence of the sharp 8 2 k event in the western north pacific region in addition our results have revealed that in the period from the last deglaciation through the holocene the synchronous temperature anomalies before and after the 8 2 k event seem to be related to meltwater outflow and reduced solar activity respectively it is important that the all temperature anomalies whether because of reduced solar activity in the late holocene or from meltwater discharge in the early holocene are accompanied by an abrupt decline in the indian ocean summer monsoon and abrupt strengthening of the east asian summer monsoon it is likely that reduced solar activity and meltwater outflow appear to modulate earth system changes in the same direction the influences could be compounded reduced solar activity and meltwater outburst both appear to act as triggers for occurrence of the el nino phenomenon in the equatorial pacific ocean which may result in broad teleconnections between the temperature anomaly in the northern hemisphere and abrupt variation of the asian monsoon

the bay of naples southern italy constraints on the volcanic structures inferred from a dense seismic survey 1 the bays of naples and pozzuoli host volcanic areas that have been active within recent history in addition the vicinities areas around the vesuvius volcano and the campi flegrei caldera are extremely densely inhabited over the past decade this situation has prompted several active seismic experiments focused on the vesuvius volcano more recently the serapis active seismic survey covered the entire bay of naples with particular attention to pozzuoli bay the processed serapis p wave travel time collection extended with a previously acquired data set has allowed the computation of the most comprehensive three dimensional p wave velocity distribution for the bay of naples which includes a small scale high resolution model of the campi flegrei caldera the joint interpretation of the velocity distribution together with both the available gravity measurements and models and the geothermal drilling information has allowed us to locate and map lithological units at depths we propose a model of the campi flegrei caldera in relation to the underlying mesozoic limestone unit in this model no magma chamber exists in the upper 6 km beneath the bay of naples the feeding system of the campi flegrei caldera is directly controlled by the tectonic structures affecting the limestone unit beneath the bay of naples two ne sw normal faults run beneath the vesuvius volcano and campi flegrei which are related to the pre pleistocene apenninic tectonics

continental subduction and three dimensional crustal structure the northern south island new zealand the three dimensional vp and vp vs structure of a region where subduction transitions to oblique transform faulting has been determined using arrival times from 579 local earthquakes recorded during a temporary deployment and 3146 earthquakes have been relocated between 40 km and 100 km depth the subducted plate is imaged as a relatively low velocity feature in the uppermost mantle reflecting the continental nature of the subducted crust in this region an increase in amplitude of this low velocity feature from northeast to southwest can be related to an increase in the thickness of the crust of the subducted plate in this direction velocity variations within the subducted and overlying plates show some spatial correlation this suggests an interaction between the plates which extends well beyond the plate interface and is consistent with other geophysical and geological evidence that the plate interface beneath marlborough is currently not accommodating much active subduction in the overlying plate the awatere fault is a major structural feature associated with a low velocity zone extending to 23 km depth there is a marked change in structure near this fault with seismic velocities being lower to the southeast a relatively high level of seismicity occurs in this region of lower seismic velocities suggesting a relationship between the two a possible explanation for this is elevated pore pressures caused by fluids derived from dehydration of the continental subducted crust the low velocity region in the overlying plate coincides with the region of most intense active deformation suggesting it is relatively weak

reconstruction of holocene monsoon history from the pearl river estuary southern china using diatoms and carbon isotope ratios this study employs a multiproxy approach in the reconstruction of holocene monsoon history from sedimentary sequences obtained from the pearl river estuary southern china a set of modern surface sediment samples were collected within and outside the estuary and a sediment core was obtained from the mouth of the estuary a range of modern environmental variables were recorded including water salinity summer winter and annual average and water depth the diatom results show a good relationship with water salinity with marine diatoms dominating the more distal samples from outside the main estuary and freshwater diatoms dominating the proximal samples influenced by higher freshwater flux this pattern is matched by the bulk organic carbon isotopes the isotope values vary between 21 1 0 3 0 for samples from the fully marine environment between 23 2 0 8 and 23 7 0 8 for samples from the mid to outer estuary brackish water environment and less than 24 7 1 3 for samples from the inner estuary close to the freshwater sources similarly the c n ratios vary from below 7 0 6 in the marine end members to over 14 8 3 0 in the freshwater end members both the diatom and carbon data from the sediment core reveal a significant increase in freshwater flux from 8500 cal yr bp resulting from the enhanced summer monsoon regime in early holocene the strength of freshwater flux reached its highest between 7500 and 6000 cal yr bp in the last 6000 years freshwater flux decreased towards present reflecting a gradual weakening of the summer monsoon

holocene moisture evolution in arid central asia and its out of phase relationship with asian monsoon history we synthesize palaeoclimate records from the mid latitude arid asian region dominated today by the westerlies arid central asia aca to evaluate spatial and temporal patterns of moisture changes during the holocene sediment records from i i takes with reliable chronologies and robust proxies were selected to reconstruct moisture histories based on a five class ordinal wetness index with assigned scores from the driest to wettest periods at individual sites for 200 year time slices the proxies used in these records include pollen and diatom assemblages sediment lithology lake levels and geochemistry mainly isotope data the results of our synthesis show that aca as a whole experienced synchronous and coherent moisture changes during the holocene namely a dry early holocene a wetter less dry early to mid holocene and a moderately wet late holocene during the early holocene most of the lakes experienced very low water levels and even dried out before ca 8 ka 1 ka 1000cal a bp hence the effective moisture history in aca is out of phase with that in monsoonal asia as documented by numerous palaeoclimate records in monsoonal asia a strong summer monsoon and humid climate characterized the early holocene and a weakened summer monsoon and drier climate prevailed during the late holocene which were mainly controlled by changes in low latitude summer insolation in contrast we propose that the pattern of holocene effective moisture evolution in the westerly dominated aca was mainly determined by north atlantic sea surface temperatures ssts and high latitude air temperatures that affect the availability amount and transport of water vapor also topography of the tibetan plateau and adjacent asian highlands could have contributed to the intensification of dry climate in aca during the early holocene as a result of strengthening the subsidence of dry air masses associated with stronger uplift motion on the plateau by intense heating under a stronger summer insolation summer insolation might have played a key role in directly controlling moisture conditions in aca but only after the northern hemisphere ice sheets had disappeared in the mid and late holocene c 2007 elsevier ltd all rights reserved

geochemical discrimination of clastic sedimentary rock sources abstract factors controlling the geochemistry of a clastic sedimentary rock can include 1 composition of source terrain 2 chemical weathering 3 hydraulic sorting 4 diagenesis 5 metamorphism and 6 hydrothermal alteration a linear solution inferring source terrain composition from geochemistry of the sediment is impossible in this multivariate system as several unknowns will commonly be present the use of graphical analysis of element pairs circumvents the problem chemically immobile elements will maintain invariant ratios during rock mass change caused by either addition or depletion of mobile elements this results in chemically immobile element scattergrams exhibiting linear trends along radians extending from the origin if the major mineral phases of the immobile elements have behaved in a hydrodynamically similar manner as chemically mobile element plots will produce a scatter of points this relationship can be used to test chemical immobility and similarity in hydrodynamic sorting history the constraint on analysis is that the source area must be compositionally uniform or the sediment well mixed prior to delivery to the basin a second technique using sio2 plots has also been developed to investigate element mobility and hydrodynamic behaviour of the mineral phases containing the elements sio2 immobile element plots result in a linear arrangement of points extending towards either 0 or 100 sio2 the 0 intercept position occurs for elements with major mineral phases concentrated in sand the 100 intercept for those concentrated in clays plotting chemically mobile elements produces different patterns and this can be used to gain information on alteration and sorting history elemental ratios for chemically immobile elements with similar hydrodynamic behaviour will be the same as those for the weighted average composition of the source material this provides a powerful tool for deducing source terrain from sediment geochemistry techniques outlined above were tested on archaean metasandstones from superior province canada immobile element ratio diagrams for nb al ti and zr al ti indicate that a calc alkaline extrusive intrusive suite lying to the north of the study area was the source and not five other volcanic suites in the region this conclusion agrees with previous clast lithology studies and accentuates the applicability of the geochemical techniques

tomographic inversion of local earthquake data from the hengill grensdalur central volcano complex iceland parameters is generally low however a quantitative analysis of resolution provides an unambiguous assessment of well resolved volumes within the better resolved regions of the model the averaging volumes are 1 2 km and 2 4 km in vertical and horizontal extent respectively results of tomographic inversion image three distinct bodies of anomalously high velocity two of these extend from near the surface to a depth of about 3 km these high velocity volumes are located directly beneath the surface expressions of the extinct grensdalur volcano and the extinct husmuli basalt shield the third high velocity structure occurs in the depth range of 3 4 km but does not extend to the surface these three high velocity bodies are interpreted to be solidified magmatic intrusions relatively low velocities underlay limited portions of the trace of the present accretionary axis and a low velocity body is imaged in the roots of the active hengill volcano the volume of lower velocities located beneath the surface expression of the hengill volcano is interpreted to be a region of partial melt

on the effects of 3 d mechanical heterogeneities at campi flegrei caldera southern italy 1 campi flegrei caldera located near the highly populated city of naples southern italy is characterized by long term subsidence punctuated by fast uplift phases most of the interpretations of the ground deformation are still based on standard models that assume the lithosphere to behave as a homogeneous half space however several geophysical investigations show the presence of vertical and lateral heterogeneities especially in the shallow subsurface which might have an effect on the interpretation of the surface displacements our 3 d finite element models constrained by seismic tomography to take into account the realistic distribution of mechanical heterogeneities demonstrate that at campi flegrei the assessment of the source location is independent of the consideration of 3 d heterogeneities while the evaluation of its strength is overestimated thus we propose an approach that still allows use of standard homogeneous half space models but accounts for 3 d heterogeneity effects this procedure applied to the deformation field revealed by differential synthetic aperture radar interferometry dinsar over the past 16 years provides new insights for the understanding of the ground displacements observed at campi flegrei caldera this work provides an approach for a quantitative evaluation of the effects of mechanical heterogeneities on surface deformation analogous procedures can be also applied in other volcanic areas where similar to campi flegrei caldera a priori information on the mechanical heterogeneities distribution is available

source parameters and three dimensional attenuation structure from the inversion of microearthquake pulse width data qp imaging and inferences on the thermal state of the campi flegrei caldera southern italy the three dimensional p wave attenuation structure of the campi flegrei caldera and the estimate of source parameters for 87 local microearthquakes is obtained by the nonlinear inversion of pulse width and rise time measurements by using the method described by zollo and de lorenzo this issue source radii represent the better resolved parameters with values ranging from 70 m to 230 m the dip and strike angles defining fault orientations are usually affected by larger uncertainties and are well constrained only for 11 events the dip fault is usually confined in the range 30 60 with an average uncertainty of 12 the fault strikes mainly range between 60 and 60 and seem to define preferential directions oriented radially from the symmetry axis of the ground deformation stress drop estimates indicate rather low values 0 01 1 mpa which suggest low strength properties of the incoherent and brittle materials filling the caldera primarily yellow tuffs the three dimensional qp images obtained from the inversion of p pulse durations show two significant low qp anomalies between 0 and 1 km of depth in the north eastern sector and at 2 3 km of depth in the central eastern sector of the caldera the high degree of spatial correlation of the low qp zone and low vs as inferred by aster and meyer 1988 at 0 1 km in depth and other geophysical and geochemical observations suggest that this anomaly can be related to the presence of densely fractured porous and fluid filled rocks in the ne sector of the caldera the deeper low qp anomaly is interpreted as being related to a dominant thermal effect we used the surface and deep borehole temperature measurements available in the area to obtain a local calibration curve to convert qp in temperature at campi flegrei the retrieved t qp map shows a high thermal deep disturbance 450 500 c at depths between 2 and 3 km in the eastern sector of the caldera where the most recent eruptive activity is concentrated the present day temperature field retrieved by qp images has been interpreted by using a three dimensional thermal conduction model assuming an extended heat source initial temperature of 800 c located underneath the attenuation anomalous region the results indicate that the qp inferred temperature field can be related to the heat conduction effect of one or more molten bodies whose top should be at about 4 km depth consistent with recent seismic estimates of the magma chamber top at campi flegrei ferrucci et al 1992 this study suggests that the present thermal state and rock rheology of the inner caldera could be controlled by the cooling of molten bodies that originally intruded at depths of 1 4 1 6 km during one or more recent time of 10 kyr eruptive events

geodetic constraints to the source mechanism of the 2011 2013 unrest at campi flegrei italy caldera campi flegrei caldera italy was affected by a new unrest phase during 2011 2013 we exploit two cosmo skymed data sets to map the deformation field obtaining displacement rates reaching 9 cm yr in 2012 in the caldera center the resulting data set is fitted in a geophysical inversion framework using finite element forward models to account for the 3 d heterogeneous medium the best fit model is a north dipping mixed mode dislocation source lying at 5 km depth the driving mechanism is ascribable to magma input into the source of the large 1982 1984 unrest since similar source characteristics were inferred that generates initial inflation followed by additional shear slip accompanying the extension of crack tips the history and the current state of the system indicate that campi flegrei is able to erupt again and the advanced techniques adopted provide useful information for short term forecasting

temporal changes of medium properties during explosive volcanic eruption volcanic evolutions typically accompany significant changes in medium properties monitoring the seismic properties may be useful in identifying the state of volcanic evolution temporal variation of shallow crustal vp vs ratios before and during the 2009 eruption of redoubt volcano alaska is investigated using the p and s traveltimes of local earthquakes high vp vs ratios of 1 9 are observed over a wide region in the precursory phase suggesting the presence of partial melts in the medium at least several months before explosive eruptions the high v p v s ratios decrease until the early effusive phase with rates of 0 179 year 1 in the precursory phase 65 days and 2 147 year 1 in the explosive phase 40 days which is equivalent to a decrease in the bulk modulus of fluids by 1 1 and 7 9 gpa respectively the decreasing v p v s ratios in the precursory phase may be due to increasing amounts of overpressurized gas and water vapor in the medium the rapid decrease in vp vs ratios during the explosive phase may be caused by melt eruption and gas emission the vp vs ratios were observed to be nearly stationary since the early effusive phase suggesting rare presence of melts and low levels of pore pressures with degassing these observations suggest that monitoring vp vs ratios may be useful to identify the eruption state

hydro geomorphic hazards and impact of man made structures during the catastrophic flood of june 2000 in the upper guil catchment queyras southern french alps the guil river valley queyras southern french alps is prone to catastrophic floods as the long historical archives and holocene sedimentary records demonstrate in june 2000 the upper part of this valley was affected by a b30 yearq recurrence interval r i flood although of lower magnitude and somewhat different nature from that of 1957 n100 year r i flood the 2000 event induced serious damage to infrastructure and buildings on the valley floor use of methods including high resolution aerial photography multi date mapping hydraulic calculations and field observations made possible the characterisation of the geomorphic impacts on the guil river and its tributaries the total rainfall 260 mm in four days and maximum hourly intensity 17 3 mm h 1 aggravated by pre existing saturated soils explain the immediate response of the fluvial system and the subsequent destabilisation of slopes abundant water and sediment supply landsliding bank erosion particularly from small catchment basins cut into slaty schist bedrock resulted in destructive pulses of debris flow and hyperconcentrated flows the specific stream power of the guil and its tributaries was greater than the critical stream power thus explaining the abundant sediment transport the guil discharge was estimated as 180 m 3 s 1 at aiguilles compared to the annual mean discharge of 6 m 3 s 1 and a june mean discharge of 18 m 3 s 1 the impacts on the guil valley floor flooding aggradation generalised bank erosion and changes in the river pattern were widespread and locally influenced by variations in the floodplain slope and or channel geometry the stream partially reoccupied former channels abandoned or modified in their geometry by various structures built during the last four decades as exemplified by the aiguilles case study where the worst damage took place a comparative study of the geomorphic consequences of both the 1957 and 2000 floods shows that despite their poor maintenance the flood control structures built after the 1957 event were relatively efficient in contrast to unprotected places the comparison also demonstrates the role of land use changes conversion from traditional agro pastoral life to a ski hikingbased economy construction of various structures in reducing the guil channel capacity and more generally in increasing the vulnerability of the human installations the efficiency of the measures taken after the 2000 flood narrowing and digging out of the channel is also assessed final evaluation suggests that in such high mountainous environments there is a need to keep

evidence for general instability of past climate from a 250 kyr ice core record recent results1 2 from two ice cores drilled in central greenland have revealed large abrupt climate changes of at least regional extent during the late stages of the last glaciation suggesting that climate in the north atlantic region is able to reorganize itself rapidly perhaps even within a few decades here we present a detailed stable isotope record for the full length of the greenland ice core project summit ice core extending over the past 250 kyr according to a calculated timescale we find that climate instability was not confined to the last glaciation but appears also to have been marked during the last interglacial as explored more fully in a companion paper3 and during the previous saale holstein glacial cycle this is in contrast with the extreme stability of the holocene suggesting that recent climate stability may be the exception rather than the rule the last interglacial seems to have lasted longer than is implied by the deep sea specmap record4 in agreement with other land based observations5 6 we suggest that climate instability in the early part of the last interglacial may have delayed the melting of the saalean ice sheets in america and eurasia perhaps accounting for this discrepancy

floods in mountain environments a synthesis floods are a crucial agent of geomorphic change in the channels and valley floors of mountains watercourses at the same time they can be highly damaging to property infrastructure and life because of their high energy mountain watercourses are highly vulnerable to environmental changes affecting their catchments and channels many factors have modified and frequently still tend to modify the environmental conditions in mountain areas with impacts on geomorphic processes and the frequency magnitude and timing of floods in mountain watercourses the ongoing climate changes vary between regions but may affect floods in mountain areas in many ways in many mountain regions of europe widespread afforestation took place over the twentieth century considerably increasing the amounts of large wood delivered to the channels and the likelihood of jamming bridges at the same time deforestation continues in other mountain areas accelerating runoff and amplifying the magnitude and frequency of floods in foreland areas in many countries in channel gravel mining has been a common practice during recent decades the resultant deficit of bed material in the affected channels may suddenly manifest during flood events resulting in the failure of scoured bridges or catastrophic channel widening during the past century many rivers in mountain and foreland areas incised deeply the resultant loss of floodplain water storage has decreased attenuation of flood waves hence increasing flood hazard to downstream river reaches on the other hand a large amount of recent river restoration activities worldwide may provide examples of beneficial changes to flood risk attained as a result of increased channel storage or reestablished floodplain water storage relations between geomorphic processes and floods operate in both directions which means that changes in flood probability or the character of floods e g increased wood load may significantly modify the morphology of mountain rivers but morphological changes of rivers can also affect hydrological properties of floods and the associated risk for societies this paper provides a review of research in the field of floods in mountain environments and puts the papers of this special issue dedicated to the same topic into context it also provides insight into innovative studies methods or emerging aspects of the relations between environmental changes geomorphic processes and the occurrence of floods in mountain rivers

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

evidence for the contemporary magmatic system beneath long valley caldera from local earthquake tomography and receiver function analysis 1 we present a new p wave and s wave velocity model for the upper crust beneath long valley caldera obtained using local earthquake tomography and receiver function analysis we computed the tomographic model using both a graded inversion scheme and a traditional approach we complement the tomographic vp model with a teleseismic receiver function model based on data from broadband seismic stations mlac and mkv located on the se and sw margins of the resurgent dome inside the caldera the inversions resolve 1 a shallow high velocity p wave anomaly associated with the structural uplift of a resurgent dome 2 an elongated wnw striking low velocity anomaly 8 10 reduction in vp at a depth of 6 km 4 km below mean sea level beneath the southern section of the resurgent dome and 3 a broad low velocity volume 5 reduction in vp and as much as 40 reduction in vs in the depth interval 8 14 km 6 12 km below mean sea level beneath the central section of the caldera the two low velocity volumes partially overlap the geodetically inferred inflation sources that drove uplift of the resurgent dome associated with caldera unrest between 1980 and 2000 and they likely reflect the ascent path for magma or magmatic fluids into the upper crust beneath the caldera

holocene forcing of the indian monsoon recorded in a stalagmite from southern oman a high resolution oxygen isotope record from a thorium uranium dated stalagmite from southern oman reflects variations in the amount of monsoon precipitation for the periods from 10 3 to 2 7 and 1 4 to 0 4 thousand years before the present ky b p between 10 3 and 8 ky b p decadal to centennial variations in monsoon precipitation are in phase with temperature fluctuations recorded in greenland ice cores indicating that early holocene monsoon intensity is largely controlled by glacial boundary conditions after approximately 8 ky b p monsoon precipitation decreases gradually in response to changing northern hemisphere summer solar insolation with decadal to multidecadal variations in monsoon precipitation being linked to solar activity

seismicity vp vs and shear wave anisotropy variations during the 2011 unrest at santorini caldera southern aegean article i nfo the santorini caldera has been the focus of several large explosive eruptions in the past the last of which occurred in the early 1950s the volcano was dormant until early 2011 when increasing number of earthquakes accompanied significant intra caldera uplift this seismic activity was recorded by 8 temporary as well as 19 permanent seismic stations that were installed on santorini and nearby islands after the onset of the unrest using data from january 2011 until june 2012 we calculated accurate relative locations for 490 events utilizing both catalog and waveform cross correlation differential travel times of p and s phases the distribution of relocatedeventsexhibits a largecluster betweenthera andnea kameni islands alongthe caldera rim suggesting the activation of a preexisting ring fault all hypocenters are located between 5 and 11 km resulting in a sharp cutoffof seismicity above and below thesedepths wealsoused p and s traveltimes inorder to calculate average vp vsratios and estimatedshear wavesplitting parameters fast direction delay time t for eventswithin the shear wave window the vp vs ratios at several stations exhibit a majority of values consistently below the regional one 1 77 their temporal variations can be explained as periods of gas influx and depletion in the upper crust beneath the caldera a comparison of t for a number of earthquake doublets shows a progressive decrease of delay times towards the end of the unrest probably as a result of cracks closing owing to stress relaxation the seismological observations presented here are compatible with petrological models that suggest the existence of a deep 11 14km dacitic magma reservoir and a shallower b5km rhyolitic magma chamber

genesis and evolution of unrest episodes at campi flegrei caldera the role of thermal fluid dynamical processes in the geothermal system we develop a model for describing water flow in a porous medium under the effect of thermal and pressure gradients the model simulates geothermal systems in calderas given the boundary conditions and the fluid dynamical properties of the medium the model allows computation in fluid dynamical stationary states of parameters characterizing the flow such as flow velocity and temperature and pressure distributions at depth the model is applied to investigate the effects of the local geothermal system on the unrest episodes at campi flegrei caldera using experimentally determined fluid dynamical parameters for the caldera rocks we show that changes of water flow in shallow aquifers under the effect of pressure and or temperature variations within the geothermal system can be very important in the genesis and evolution of unrest crises in particular they can strongly amplify the effect of pressure increase in the magma chamber on ground uplift they can also explain the timescales of evolution of ground movements in terms of transit times of the water front and of the connected temperature fronts due to advective transport on such grounds an integrated mechanic thermal fluid dynamical model was built allowing us to give a semiquantitative global explanation to the genesis and evolution of unrest phenomena results obtained here can be generalized to other similar calderas

geomorphological response to an extreme flood a case from southeast spain on 28 29 september 1980 an extreme storm of 150 mm of rain in c 5 hours caused a flash flood near tabernas in a semi arid area in southern spain with the rainfall total approximating the mean annual rainfall the recurrence interval is estimated to be 25 100 years flood peak discharges have been estimated from a mountain source area across an alluvial fan and the geomorphological response to the storm described channel adjustment differed between channels in the fanhead trench and those unconfined channels on the fan surface the implications of the spatial pattern of erosional an depositional feaures for landform adjustment in semi arid regions are discussed

biogeochemical evidence of holocene east asian summer and winter monsoon variability from a tropical maar lake in southern china abstract lake huguangyan 21 9 n 110 17 e a maar lake located near the south china sea can provide valuable sedimentary data regarding past changes of the east asian monsoonal system here we used the proxies of toc 13corg 15n and leaf wax n alkane 13c values 13cwax to reconstruct the lake conditions which in turn revealed patterns in monsoonal changes during the holocene two distinct patterns of proxy changes were identified in the sedimentary profile a marked shift in the 13cwax value at 9 2 ka thousand years ago suggests the abrupt disappearance of c4 plants signaling the enhancement of east asian summer monsoon easm between 9 2 and 1 8 ka a nearly pure c3 terrestrial ecosystem was present with the climax at ca 7 6 ka after ca 3 ka fewer tropical species and a reappearance of c4 plants at 1 8 ka indicate a weakened easm in the late holocene the toc concentration and 15n value proxies appear to be associated with lake aquatic production and upwelled nutrient supply and utilization which are modulated by and thus indicative of the strength of the east asian winter monsoon eawm the two eawm records suggest a weakening trend from the early to late holocene with the most significant transition at 6 ka thus the eawm trend was broadly in phase with that of the easm however the marked easm intensification at 9 2 ka occurred within the period of a strong eawm between 10 5 and 6 ka and lagged the monsoonal enhancement as inferred from the dongge cave 18o values our easm records displays an overall arid wet arid pattern which is in phase with the hydrological variability in tropical australia and anti phase with that in the outer tropical andes these phase relationships might be linked to changes in the thermal state of the tropical pacific during the holocene

seismological studies at parkfield i simultaneous inversion for velocity structure and hypocenters using cubic b splines parameterization a model for the 3d p and s wave velocity structure at parkfield has been developed by the systematic inversion of arrival times for microearthquakes and surface vibroseis sources recorded by nearby calnet stations and by the local borehole installed 10 station high resolution seismic network there a modification of the linear b splines model parameterization method of thurber 1983 to a cubic b splines formulation through tests inverting synthetic data sets for the parkfield configuration is found to produce smooth velocity distributions that still retain some small scale features application of the method to 953 p wave and 288 s wave arrivals from 111 microearthquakes and 8 vibroseis locations throughout the study area yields a velocity structure having variable resolution a low velocity zone appears to coincide with the creeping segment of the san andreas fault zone northwest of the 1966 parkfield earthquake epicenter an increase of about 15 per cent in seismic velocities is seen from the northeast to southwest across this segment of the fault zone the higher velocities to the southwest apparently correspond to the granitic basement the contrast across the fault is subdued to the southeast along the 1966 rupture zone a high vp vs ratio of 1 9 is seen in a 2 km wide volume near the location of the 1966 main shock hypocenter presumably the nucleation zone for the expected m 6 parkfield earthquake