validity of the environmental chloride method for recharge evaluation of coastal aquifers india the work presented in the paper was carried out with the objective of ascertaining the validity of environmental chloride method for evaluation of groundwater recharge to the coastal aquifers situated in semi arid tropical area under the influence of monsoonic type of hydrologic regime towards this end a comparative study using environmental chloride in conjunction with injected tritium method the more commonly used method was undertaken in the coastal aquifers of pondicherry situated about 160 km south of madras along the coast of bay of bengal five each of environmental chloride repeated twice and injected tritium profiles were studied in the alluvium and cuddalore aquifers of pondicherry recharge from the chloride study was estimated using 1 concentration approach which involves estimating the relative enrichment of soil chloride concentration in relation to the input chloride and 2 flux approach determining the turnover time of soil moisture by estimating the total chloride in the profile and yearly input recharge from the injected tritium profiles was estimated by studying the displacement of soil moisture during the time interval between sampling and injection of the tracer repeated chloride profiles show fairly good reproducibility within 15 30 of recharge rates determined by the two approaches for two different sampling times at the same site also the results compare well among the two approaches used for the chloride method mean recharge rates obtained by the injected tritium method for the cuddalores is about 26 cm yr 1 and by the chloride method about 22 cm yr 1 and for the alluvium the respective rates are 10 and 14 cm yr 1 this shows fairly good agreement between the two methods the study thus demonstrates conformity of recharge rates determined by the environmental chloride method and injected tritium technique and proves the validity of the chloride method for recharge measurements for tropical coastal aquifers situated in semi arid regions

potential analogues for paleoclimatic variations in eastern interior alaska during the past 14 000 yr atmospheric circulation controls of regional temperature and moisture responses the paleoclimatic history of a region can be viewed as a series of surface temperature and moisture anomalies through time the effects of changes in large scale climatic controls e g insolation major circulation controls can be mediated by the influence of smaller scale controls e g topographic barriers coastlines this may result in heterogenous surface climatic responses at the regional and sub regional scale divergent paleoclimatic trajectories between regions may be explainable in terms of such meso scale patterns using modern analogues for paleoclimate we examine how the sequence of climatic variations in eastern interior alaska during the interval 12 000 0 14c yr bp could have been generated by specific atmospheric circulation patterns fossil pollen and lake level records document the long term trends in temperature and effective moisture for the region water balance modelling provides additional estimates of paleoprecipitation synoptic climatological patterns are described using the modern instrumental record of upper level and sea level pressure surface temperature and precipitation at 12 000 14c yr bp eastern interior alaska was cooler and drier than present a situation generated today by a southward displacement of the jet stream conditions warmer and drier than present at 9000 14c yr bp may have been generated by increased ridging north of alaska and a weakened westerly circulation warmer wetter conditions than present possibly prevailed in the late middle holocene these might reflect ridging over alaska and troughing further west cool wet conditions feature enhanced westerly flow into alaska through an eastward shift in the east asian trough and positive pressure anomalies in the north pacific they may be analogous to cold periods of the little ice age the analogues demonstrate how surface conditions in other parts of beringia may sometimes be similar to while at other times different from those in the eastern interior these broader spatial patterns provide hypotheses about past climates that can be tested with paleoclimatological data for example the widespread positive temperature anomalies associated with the warm dry 9000 14c yr bp analogue fit with the expansion northward of the eastern siberian treeline the anomalously cool conditions in northeast siberia associated with the warm wet analogue may explain the continued late middle holocene treeline advance in alaska while there was retreat in siberia

self excitation process due to local seismic amplification responsible for the reactivation of the salcito landslide italy on 31 october 2002 1 an integrated numerical and geophysical approach was used to investigate the role of local seismic amplification in the reactivation of the salcito landslide italy after the molise earthquake of 31 october 2002 numerical stress strain analysis with flac 5 0 fdm software performed in dynamic configuration showed that the 1 hz frequency was consistent with landslide instability conditions the fourier spectrum of the triggering earthquake showed two main peaks occurring at 1 and 2 hz respectively which could be related to local effects the analysis of h v spectral ratios of ambient noise records obtained in the landslide area evidenced amplification effects in the 1 3 hz range on the basis of an engineering geology model numerical modeling of both 1 d and 2 d seismic wave propagation was conducted using linear and nonlinear solutions the simulation outputs showed 1 a 1 hz amplification ascribable to 2 d effects due to a landslide mass lying within a basin like geological structure 2 a double peak amplification at about 2 and 3 hz respectively ascribable to 1 d resonance of the landslide mass and 3 1 d plus lateral wave effects within the landslide mass in the 2 5 3 5 hz frequency range these findings suggest that local amplification of ground motion by the salcito landslide mass may generate a self excitation process responsible for its reactivation

contrasting styles of explosive eruption at sete cidades sao miguel azores in the last 5000 years hazard implications from modelling abstract the deposits of three eruptions in the last 5000 years are described in detail in order to constrain eruptive parameters and allow a quantitative assessment of the hazard from a range of explosive eruption types at sete cidades volcano sao miguel azores these deposits include the caldeira seca eruption p17 which occurred around 600 yr bp which was the last explosive event from inside the sete cidades caldera the p11 eruption dated at 2220 70 yr bp and the undated p8 eruption our studies reveal that the caldeira seca eruption p17 produced ash rich deposits probably as the result of hydromagmatic eruptions and several lapilli fall layers dispersed in different directions the lapilli fall layers were derived from eruption columns up to10 km high evidence indicates pyroclastic density currents pdcs only moved outside of the caldera on to the western flank the p11 deposit represents one of the largest eruptions at sete cidades in the last 5000 years the deposits are composed of two units the main lower one is a lapilli fall deposit inferred to be derived from an eruption column 18 km high evidence for pdcs outside of the caldera occurs to the southeast and northwest the p8 deposits are composed of numerous alternating lapilli and ash layers representing a highly pulsatory eruption almost all of which are of a fallout origin the lapilli are inferred to be derived from eruption columns up to 8 km in height using the eruptive parameters derived from these deposits we use hazmap macedonio g costa a longo a 2005 a computer model for volcanic ash fallout and assessment of subsequent hazard comput geosci 31 837 845 to constrain the probability of fallout of different loads and thicknesses two end member scenarios were used with hazmap one representing a p17 eruption and another representing a p11 eruption both scenarios use wind profile data averaged over 25 years for a p17 type event there is a 5 chance of tephra fallout exceeding 15 cm thickness in ponta delgada the capital of sao miguel indicating that roof collapse associated with such an event is unlikely the larger magnitude and higher intensity p11 type eruption provides a 5 probability that tephra loads thicknesses would exceed 92 cm in ponta delgada and that roof collapse could be a major problem to assess the distribution of pdcs from future eruptions we use a gis application of the energy line model toyos g cole p d felpeto a marti j 2006 a gis based methodology for hazard mapping of small volume pyroclastic density currents nat hazards 41 99 112 the model indicates that individual pdcs of up to 10 7 m 3 derived from a vent located centrally within the caldera and a fountain collapse height of 500 m above the caldera floor could be completely contained within the caldera however pdcs derived from a vent located at caldeira seca in the western part of the caldera show individual pdcs 10 5 m 3 would travel out of the caldera and down the western flank as the vent location from a future eruption within the sete cidades caldera is unknown the hazard from pdcs is high for anywhere on the immediate flanks of the volcano

paleodrainage on the chukchi shelf reveals sea level history and meltwater discharge abstract chirp subbottom data collected across the chukchi shelf offshore nw alaska imaged numerous paleochannels and valleys that appear to have been downcut and incised during sea level falls associated with glacial intervals in contrast the two most recent incisions appear to have been formed during the period of sea level rise following the last glacial maximum lgm the architecture and infill associated with these two incisions suggests that they were formed by an increase in discharge these events appear to be unrelated to sea level fluctuations but rather triggered by climatic variations during the most recent deglaciation i e meltwater discharge radiocarbon dates from sediment cores within the southern incised valley suggest that the two episodes of meltwater discharge may correlate with meltwater pulse 1 a 14 000 cal yr bp and evidence of iceberg scouring on outer chukchi shelf 12 000 to 13 000 cal yr bp respectively regional transgression across the interfluves on the middle chukchi shelf appears to postdate the second meltwater discharge and may correlate with meltwater pulse 1 b 11 500 cal yr bp this evidence suggests that in glacially dominated landscapes episodes of large discharge to the shelf might be out of phase with the sea level cycle in addition the presence of glacial meltwater drainage on the shelf implies a greater volume of continental glaciation during the lgm than previously recognized

rock fall hazard assessment in asar hill ancient mabolla city mugla sw turkey this paper discusses the potential rock fall hazard of asar hill this flat topped hill containing upper miocene conglomerate and finer grained sedimentary rocks hosts to the ancient mabolla city the seasonal temperature differences are high in this rainy region block sizes bed and joints attitudes were measured along three profiles during field study schmidt hammer was applied to grains and matrix of conglomerates for determining strength in situ one joint set in profile a 3 in profile b and 4 in profile c were determined via dips analysis an intersection of joints and bedding directed 25 35 nw caused the block formation control slope angle and mass movement type at least 10 blocks 0 6 1241 085 tons were fixed on top of profiles two blocks on top of the eastern profile a contain archaeological ruins after back analysis for determining restitution coefficients rocfall version 4 9 software program was used to determine possible end points of those blocks most of the blocks can reach the valley and pass the other side which includes settlements and gardens consequently the possible rock fall hazard in asar hill is threatening visitors and settlers the cleaning of detached blocks on top of slope is one of the easiest ways however in situ preservation of blocks with archaeological ruins via tensioned rock anchors and or patterned rock bolts has vital importance relocation of settlers and gardens opening trench around hill and establishing green belt forest would be considered as other measures

intensity versus ground motion a new approach using italian data abstract the correlations between macroseismic intensity and peak ground acceleration and between macroseismic intensity and arias intensity are compared the data base consists of 56 records 168 time histories related to ns ew and z components derived from nine italian earthquakes that occurred between 1980 and 1990 the intensity data have been determined using two approaches 1 the standard approach which is a general description of the effects on a certain village town general intensity and 2 a localized approach based on a description of effects in the immediate vicinity and in the same lithological morphological and hydrogeological conditions as the recording instrument itself local intensity this second approach to determining intensity could more closely approximate the ground motion parameters obtained from the accelerograms indeed the results of the regressions that were performed show a clear improvement in the correlation when using the local instead of the general intensity in a comparison with peak ground acceleration arias intensity

analysis on mechanism of landslides under ground shaking a typical landslide in the wenchuan earthquake a high steep rock hill with two side slopes near national road 213 is used as a prototype in this paper the full process from initial deformation to sliding of the slope during ground shaking is simulated by a new discrete element method continuum based discrete element method then the seismic responses of a high steep rock hill with two side slopes are researched from the base of time frequency and joint time frequency domain using hilbert huang transform and fourier transform the findings are first the stress concentration phenomenon occurs at the top of the sliding mass and then some tension and shear failure points appear which expand from the top toward the toe of the sliding mass along the structural plane at the same time the number of tension failure points gradually increases then the toe of the sliding mass fails and shears out from its toe which results in the landslide if the material parameters are under the same conditions the landslide in the middle of the slope occurs before that at the foot of slope and the starting time of landslide and the arrival time of the peak ground acceleration are synchronous or the former slightly lags behind the latter the difference of distribution and dissipation of earthquake energy in the sliding body and sliding bed is the major influence factor to induce the landslide when the accelerations are small the instantaneous frequency of accelerations between sliding bed and sliding body is generally consistent the energy transmittance coefficients of the sliding structural plane and the controlled frequency band of the energy all range in a limitation with the increase of the seismic intensity the instantaneous frequency and the energy transmittance coefficients gradually decrease and then they are steady within the lower limitation at the same time the controlled frequency band also shifts gradually from high frequency band to the lower one based on the input seismic wave the peak acceleration amplifies as the increase of elevation regardless of the monitoring points on the steep slope gentle slope side or inside of the slope generally speaking amplification of the vertical peak acceleration is stronger than that of the horizontal peak acceleration and amplification of the peak acceleration on a steep slope is stronger than that on a gentle slope and that of inside of the slope is the weakest amplification

rainfall patterns and critical values associated with landslides in povoacao county sao miguel island azores relationships with the north atlantic oscillation sao miguel island azores has been affected by hundreds of destructive landslide episodes in the last five centuries triggered either by earthquakes volcanic eruptions or rainfall episodes which were responsible for many deaths and very important economic losses among the instability causes meteorological factors are of primary importance on povoacao county namely the high recurrence rate of calamitous rainfall triggering landslides the most recent catastrophic episode took place on the 31st october 1997 when almost 1000 soil slips and debris flows were triggered and 29 people died in the ribeira quente village the role of rainfall on regional landslide activity was analysed applying cumulative rainfall methods the method comprises the reconstruction of both absolute and calibrated antecedent rainfalls associated with each major landslide event the critical rainfall combination amount duration responsible for each landslide event was assessed and a rainfall critical threshold for landslide occurrence was calculated rainfall triggered landslides in the study area are ruled by the function i 144 06 d 0 5551 and they are related both to short duration precipitation events 1 3 days with high average intensity between 78 and 144 mm day and long lasting rainfall episodes 1 5 months with a lower intensity between 9 and 22 mm day the impact of the north atlantic oscillation nao on the regional precipitation regime was evaluated it is shown that the monthly precipitation of sao miguel is largely modulated by the nao mode presenting a significant negative correlation with the nao index this result arises from the nao control on the travelling latitude of most storm tracks that cross the northern atlantic ocean copyright 2007 john wiley sons ltd

bottom characterization of lagoa das furnas on sao miguel azores archipelago abstract lagoa das furnas is a crater lake located in an area exposed to geohazards from earthquakes and volcanic activity on the island of sao miguel in the azores archipelago geophysical mapping of lagoa das furnas reveals a previously undiscovered volcanic dome this dome is comprised largely of subaquatic pyroclastic debris of trachytic composition sedimentological petrological geochemical and geochronological studies of pyroclastic deposits from the dome link it to the historically documented furnas 1630 eruption the chemistry of glass and crystal fragments sampled from the dome suggests that it is comprised of more evolved magma than that of the main furnas 1630 dome located 1400 m away this suggests that the dome was formed during a final phase of the 1630 eruption in the lagoa das furnas area

last glacial maximum to holocene sea surface conditions at umnak plateau bering sea as inferred from diatom alkenone and stable isotope records 1 the bering sea gateway between the pacific and arctic oceans impacts global climate when glacial interglacial shifts in shore line position and ice coverage change regional albedo previous work has shown that during the last glacial termination and into the holocene sea level rises and sea ice coverage diminishes from perennial to absent yet existing work has not quantified sea ice duration or sea surface temperatures sst during this transition here we combine diatom assemblages with the first alkenone record from the bering sea to provide a semiquantitative record of sea ice duration sst and productivity change since the last glacial maximum lgm during the lgm diatom assemblages indicate that sea ice covered the southeastern bering sea perennially at 15 1 cal ka b p the diatom assemblage shifts to one more characteristic of seasonal sea ice and alkenones occur in the sediments in low concentrations deglaciation is characterized by laminated intervals with highly productive and diverse diatom assemblages and inferred high coccolithophorid production at 11 3 cal ka b p the diatom assemblage shifts from one dominated by sea ice species to one dominated by a warmer water north pacific species simultaneously the sst increases by 3 c and the southeastern bering sea becomes ice free year round productivity and temperature proxies are positively correlated with independently dated records from elsewhere in the bering sea the sea of okhotsk and the north pacific indicating that productivity and sst changes are coeval across the region

directivity of slope dynamic response to seismic shaking 1 a four year long accelerometric monitoring of a landslide prone slope area in italy provided evidence of amplifications with systematic directional differences in shaking energy by a factor of 2 3 apparently correlated with the directions of local topographic features the examination of regional scale data revealed similar site response directivity phenomena also on some steep rock slopes not affected by amplification the spectral properties of the site responses were investigated using hvsr analysis and a new approach based on the multiplication of spectra from several events the results suggest that such phenomena are caused by a directional redistribution of spectral energy controlled by a combination of interrelated topographic and geologic factors acting in similar directions

evaluation of rock slope stability for a touristic coastal area near kusadasi aydin turkey the study area which will be open to tourism in kusadasi aydin has steep and high cliffs on the aegean coast in turkey flysch is the main lithological unit and consists of alternating sandstone claystone marl sequences some sliding and rockfall problems have occurred in the area in the past so potential geological hazards need to be investigated to ensure the safety of tourists the aim of this study is to mitigate geological hazards by recommending engineering solutions which will ensure the continuation of the nature friendly appearance of the slopes to accomplish these tasks a geological survey was performed it involved gathering information on rock discontinuities by means of scan line surveys and collection of rock samples furthermore in situ and laboratory tests were also carried out the data collected from the field and laboratory test results were used to perform slope stability and rockfall 2 d and 3 d analyses for different slope conditions along 43 profiles based on the analyses rockfall was found to be the main slope instability problem in the study area under the light of these studies rock removal drainage greening vegetation filling of caverns protective wall building and erosion prevention are offered as remedial measures

risk assessment of residential buildings for an eruption of furnas volcano sao miguel the azores this paper presents the results of a study of the risks to human settlements of a future eruption of the furnas volcano in the azores it makes use of previous geological studies to estimate the likely impact of the volcanic hazards on the surrounding settlements given an eruption comparable with the last major eruption in the island in 1630 it presents the results of a comprehensive building by building survey of the settlements at risk to determine the exposure of the residential building stock to these hazards and it uses data from recent experience of volcanic eruptions elsewhere to estimate the vulnerability of the buildings to each hazard and the likely scale of human casualties and building damage the paper concludes with some recommendations for preparedness and protective measures which could be taken before an eruption to reduce the risk of human casualties from roof and building collapses principal among these are recommendations for strengthening the lateral load resistance of buildings built with the traditional vernacular techniques to better resist groundshaking during eruptions and earthquakes upgrading local building code requirements with view to increasing the live load resistance of roofs to levels similar to those applied in areas of heavy snowfalls to prevent roof collapse from tephra loading other preparedness measures are also discussed with respect to volcanic earthquakes volcanic bomb impact pyroclastic flows and tephra falls many aspects of this paper are relevant to other volcanic areas around the world

extensive perched aquifer and structural implications revealed by 3d resistivity mapping in a galapagos volcano abstract due to the complexity of geological formations and limited subsurface data in volcanic islands hydrogeological conceptual models can differ from one island to another and for the same island the galapagos islands like most inhabited volcanic islands face important water resource problems which might have a major impact on their unique and pristine ecosystems endanger world heritage list june 2007 the scarcity of geological and hydrological data combined with the difficulty of access for field measurements lead to a poor understanding of the island hydrogeology and unconvincing interpretation of traditional geophysical data here we present three dimensional 3 d resistivity maps for the supposedly waterless santa cruz island obtained by using the skytem device a helicopter borne transient electromagnetic method the latter is non invasive and measurements over inaccessible terrain were of vital importance we show that even in high relief terrain with extreme subsurface resistivity contrasts 1 6 000 ohm m the method is sensitive to low resistivity layers of hydrogeological interest 50 200 ohm m to a depth of approximately 300 m the unique spatial resolution and 3 d view of the subsurface resistivity structures allow identification of two zones of hydrogeological importance a previously unknown extensive perched aquifer 50 km 2 on the southern mountain side and the geometry of the salt water wedge in the basal aquifer located with an accuracy of a few meters this finding supports the existence of hidden perched aquifers on basaltic islands until now only inferred from hydrogeological studies it is seen to be affected by faulting beyond the vital implications for water resource and ecosystem management in the unique yet severely threatened galapagos islands some conceptual flow models of volcanic islands have to be reconsidered the presence of such structures in a volcanic edifice recognized as low strength layer may help to explain the origin of potentially catastrophic landslides

evaluating seismically induced mass movement hazard in caramanico terme italy abstract mass movements and earthquakes represent two major geological hazards in the municipal territory of caramanico terme south central apennines available records revealed the contemporaneous occurrence of earthquakes and slope failures on four occasions in the last four centuries 1627 1706 1933 and 1984 these events with local intensities ranging from vi to ix generated mass movements varying from a rotational slope failure to rock block falls all occurred in the southern periphery of the town and involved a thick carbonate megabreccia caprock and coarse colluvia which overlie a clayey substratum field investigation and review of historical records helped to delimit the areas susceptible to seismically triggered rockfalls the mapping of historic and pre historic rockfall deposits revealed their dispersal patterns and provided the basis for a determination of potential hazard zones we approximate the temporal hazard assessment by relating the rockfall occurrence to the probability of earthquake triggering considering the vi degree triggering threshold indicated by local historical data the statistical analysis of the regional seismic activity shows that events capable of inducing rockfalls have an approximately decennial recurrence in caramanico the approach presented could be readily applied to other potential risk areas of italy by exploiting the rich long term record of historical seismicity in general temporal hazard estimates at relatively low intensity levels will be possible even where the seismic history of the site is only well documented for a relatively limited time interval provided that this interval is much longer than the recurrence time of the events exceeding the threshold considered

sea level changes an integrated approach sea level changes an integrated approach in october 1985 sepm sponsored a four day conference entitled sea level changes an integrated approach the purpose of the conference was to provide a forum for an interdisciplinary exchange of ideas on sea level changes and to provide an opportunity for integrating various types of evidence in approaching unresolved issues the conference was successful in bringing together scientists from industry academia and government representing all of the major geosciences disciplines presentations of many new papers plus significant releases of data that were previously held proprietary provided fertile ground for discussion this much cited volume represents the best of the material presented at the conference includes the early vail chart

landslide hazard mapping using an expert system and a gis this paper presents a rule based expert system used to create landslide warning and alert maps using as input change of landuse data from earth observation as well as geological rainfall and earthquake data stored in a geographic information system the difference with other systems is in the use of change differential input data the system is tested with 16 documented landslides it can predict 11 of the 16 landslides to be among the 10 most at risk pixels in the area of study which covers 100 km2

responses to and the short and long term impacts of the 1957 1958 capelinhos volcanic eruption and associated earthquake activity on faial azores the 1957 58 capelinhos eruption on faial island in the azores is well known for being an excellent example of surtseyan hydromagmatic volcanic activity less well known are the responses of the portuguese authorities to the eruption and subsequent earthquake in may 1958 and the ways in which well thought out and generally effective recovery programmes were put in place at the time portugal was ruled by a dictatorship the estado novo new state only superficially similar to other fascist governments in southern europe the estado novo collected huge amounts of data on the responses of the authorities to the disaster and their programmes of recovery but never encouraged academic evaluation of policy although it ensured that the scientific aspects of the eruption and earthquake were meticulously recorded and published in this paper we remedy this situation by discussing the details of the immediate response to the emergency and the ways in which the island recovered in its aftermath the study is based not only on archival sources and demographic and economic data but also on detailed interviews with survivors some of whom were also decision makers we argue that response recovery and rehabilitation were generally highly successful and assess the lessons of the 1957 58 emergency which are relevant to future geophysical disasters in faial and the wider azores since the 1974 revolution portugal has been a democratic state we conclude that both the legislation and the civil defence infrastructure necessary to achieve a similarly strong and successful response are in place today

understanding rainfall landslide relationships in man modified environments a case history from caramanico terme italy the expansion of caramanico terme in this century has led to the urbanization of marginally stable valley slopes and this has coincided with the apparent acceleration of landslide processes recent landslides on man modified slopes were caused but not necessarily triggered by heavy precipitation antecedent moisture was a more critical factor than the amount of storm rainfall because no important landslides on natural slopes in the same period were reported in the caramanico area a clear distinction must be made between natural settings and those modified by man when determining rainfall thresholds for predictive purposes in recently urbanized mountainous environments the thresholds used to assess landslide hazards should not be weighted too heavily on old historical records of precipitation and associated mass movements instead more weight ought to be given to the period following the occurrence of any major anthropogenic and natural e g high magnitude earthquake modification of slope setting

forecasting where larger crustal earthquakes are likely to occur in italy in the near future a forecast of future occurrences of larger m 5 9 crustal earthquakes in italy is made on the basis of historic and instrumental seismicity and following a seismotectonic regionalization recently derived on the basis of geological evidence combined with earthquake epicenters and focal mechanisms completeness problems in the seismic catalog allow one to study only 20 regions out of 58 large crustal seismicity within each seismogenic region is modeled as either a periodic gauss process or a random poisson process according to the experimental coefficient of variation of the series of past occurrences in each region return times are estimated directly from the series of m 4 5 earthquakes if they are sufficient in number or from the gutenberg richter law applied to lower magnitude seismicity m 4 5 otherwise the immediate probability of an m 5 9 crustal seismic event is esti mated to be very low in all regions except southeastern sicily and appennino abrnz zese in the near future next 20 yr the estimated probability is high above 65 also in the appennino forlivese and naso capo d orlando regions in addition to detailed seismic risk reevaluations these regions represent the best bet for a program of intensive monitoring to gather a record of the process of strain accumulation and seismic release

quaternary glacial lacustrine and fluvial interactions in the western noatak basin northwest alaska abstract the 130 km long noatak basin is surrounded by mountains of the western brooks range middle and late pleistocene glaciers flowing southeast into the basin dammed a succession of proglacial lakes defined by shorelines outlet channels and upper limits of wave erosion more than 60 bluffs along the noatak river and its principal tributaries expose glacial and glaciolacustrine sediments that exhibit cut and fill relationships with interglacial and interstadial river channel and floodplain deposits this report focuses on the western noatak basin where high bluffs created by deep postglacial erosion record four major glacial advances during the cutler advance a floating ice tongue terminated in a large proglacial lake that filled the noatak basin the retreating glacier abandoned a trough along the valley center that subsequently filled with about 40 m of sediment during several younger glaciations and probably two major interglacial episodes alluvium that formed near the beginning of the younger interglaciation contains the 140 000 yr old old crow tephra the subsequent closely spaced okak and makpik advances are clearly younger than the maximum of the last interglaciation but they preceded a middle wisconsin 36 30 ka nonglacial interval in the noatak basin the okak advance terminated in an extensive lake whereas glaciers of the makpik and the subsequent anisak advances flowed into much narrower lakes that filled only the basin center the anisak advance bracketed by radiocarbon ages of about 35 and 13 6 ka represents the last glacial maximum lgm in the western noatak basin correlations with the oldest and youngest glacial deposits of the central brooks range are clear but relationships to events of intermediate age are more tenuous early pleistocene and older glacial advances from the central brooks range must have filled the noatak basin and overflowed northward through howard pass a younger glacial advance of inferred middle pleistocene sagavanirktok river age extended down the noatak valley into the basin center but its deposits are deeply buried beneath the basin floor and must be older than the cutler moraine the cutler advance may have been synchronous with the older of two advances of itkillik i age in the atongarak creek area but other evidence indicates that the okak makpik moraine succession more likely was synchronous with the two atongarak creek moraines radiocarbon ages surface morphology soil and weathering profiles and lake level history all support correlation of the last anisak major glacial advance in the western basin with the douglas creek moraine farther east and with itkillik ii late wisconsin glaciation of the central brooks range

tephra cushioning of ballistic impacts quantifying building vulnerability through pneumatic cannon experiments and multiple fragility curve fitting approaches abstract ballistic projectiles are the most frequently lethal volcanic hazard close to the vent recent eruptions of ontake in 2014 and kusatsu shirane in 2018 showed that un reinforced timber framed buildings those typically considered highly vulnerable to the dangerous penetration of ballistics provided life saving shelter from ballistic impact modelled kinetic energies of some non penetrating impacts were an order of magnitude above expected penetration thresholds it has been hypothesised that a pre existing layer of tephra on the roofs cushioned impacts to quantitatively test this and improve our understanding of how buildings respond to projectile impacts we used a pneumatic cannon to simulate block impacts to clay tiles and reinforced concrete roof slabs covered with tephra layers 0 20 cm thick substantially higher impact energies were resisted when tephra was present with 5 cm of tephra approximately tripling the penetration threshold of both building materials fragility curves which relate ballistic hazard intensity with the probability of building damage were developed from our experimental data following three curve fitting approaches generalised link models cumulative link models and data binning a key benefit of these approaches is that confidence in these curves can be robustly quantified from the data the first time that this has been attempted for volcanic fragility curves this study shows how the extent of building damage can be strongly influenced by the sequence of volcanic hazards and provides an example of proactive risk management through testing of physical mitigation strategies in a laboratory environment

assessment of rockfall hazard around afyon castle turkey the afyon castle is a tourist destination and a historical site in the city of afyon in turkey the castle is located on a steep hill with a height of 226 m in close proximity to the castle there are settlements the hill consists of trachitic andesite the rock contains columnar joints and flow layering owing to these discontinuities blocks of varying sizes had fallen down the settlement areas near the castle are now in danger because of the rockfall risk in this study rockfall analysis was carried out along nine profiles of the hill fall out distance bounce height kinetic energy and velocity of the rocks along each profile were investigated the results of the analyses were evaluated and the areas delineated as susceptible to rockfall risk are highlighted remedial measures including rock bolts and protective fences were suggested on the basis of the field observations and the rockfall risk evaluation

seismic gap hypothesis ten years after the seismic gap hypothesis states that earthquake hazard increases with time since the last large earthquake on certain faults or plate boundaries one of the earliest and clearest applications of the seismic gap theory to earthquake forecasting was by mccann et al 1979 who postulated zones of high medium and low seismic potential around the pacific rim in the 10 years since there have been over 40 large m 7 0 earthquakes enough to test statistically the earlier forecast we also analyze another forecast of long term earthquake risk that by kelleher et al 1973 the hypothesis of increased earthquake potential after a long quiet period can be rejected with a large confidence the data suggest that contrary to these forecasts places of recent earthquake activity have larger than usual seismic hazard whereas the segments of the circum pacific belt with no large earthquakes in recent decades have remained relatively quiet the clustering of earthquake times does not contradict the plate tectonic model which constrains only the long term average slip rate not the regularity of earthquakes

volcanz a volcanic loss model for auckland new zealand abstract volcanz is a probabilistic volcanic loss model developed for the auckland region in new zealand that currently considers tephra fall hazards from the auckland volcanic field avf tuhua volcano okataina volcanic centre taupo volcano tongariro volcanic centre and egmont volcano in this first version of the model structural and non structural damage to residential building envelopes and associated cleanup costs are calculated using monte carlo simulation volcanz assigns a minimum and maximum damage value to groups of buildings for every simulation dependent on tephra thickness a central damage value representing loss as a percentage of total replacement cost is then randomly selected between these limits even with small thickness falls non structural damage is expected to roof and wall coatings air conditioning units aerials and satellite dishes due to the corrosive and abrasive properties of tephra an average loss of 583 attributed to non structural damage was assigned to all residential buildings impacted by any thickness of tephra greater than 0 1 mm the costs of tephra removal from buildings cleaning of building exteriors and tephra transport and disposal are also calculated within the model assuming much of the cleanup process will be carried out by homeowners losses from all simulations are plotted against calculated average recurrence intervals aris to produce loss curves structural damage does not become apparent until aris of approximately 8000 years 1 billion losses due to structural damage occur at about 35 000 years and this increases to about 26 billion at 1 million years loss due to non structural damage is constant at approximately 160 million for aris above about 600 years between 600 and 3000 years cleanup loss is approximately 50 million increasing to over 450 million at a return period of 1 million years at aris between 600 and 3000 years total loss is approximately 210 million increasing to 10 billion at 100 000 years and over 26 billion at 1 million years because we only consider residential building damage and associated cleanup these values greatly underestimate total loss from the next volcanic event to impact auckland loss calculations will be improved by adding additional hazard and loss modules to volcanz resulting in a complete catastrophe loss model

geological hazards in the azores archipelago volcanic terrain instability and human vulnerability abstract the islands of the azores archipelago are geologically young and located in a tectonically and volcanically active region not surprisingly the islands are subject to many geological hazards including earthquakes landslides and coastal erosion some selected examples are discussed in this paper as demonstrated by two recent earthquakes 1980 terceira 1998 faial the principal damage was related to one or more of these factors 1 unsafe location of structures near faults 2 unstable foundation soils 3 poor quality of building materials and construction methods 4 disregard of building codes and 5 lack of building maintenance major landsliding events in the azores e g ponta da faja ribeira quente and faja dos cubres typically are triggered by intense long duration precipitation and or earthquake induced ground shaking the loose unconsolidated nature of the rocks and soils of these volcanic islands is another significant contributing factor sometimes aggravated by ground instability caused by human activity coastal erosion is prevalent on the north coast of sao miguel and the south coast of faial mostly resulting from natural circumstances e g steepness of cliffs differential erosion intense wave action during storms and also from human activity e g poorly engineered drainage works on cliff faces where severe coastal erosion can pose a risk to populations and societal infrastructures situated near the tops of the seacliffs to mitigate the risk of these and other geological hazards in the azores it is necessary to 1 prepare hazards and risks maps of the affected areas 2 adopt prudent land use planning that considers the hazards 3 upgrade the building codes in the hazardous areas 4 initiate slope stabilization programs 5 preserve the natural environmental integrity of the regions and 6 educate the affected populace and governmental officials about the possibilities and consequences of hazardous processes

forensic assessment of the 1999 mount cameroon eruption west central africa abstract the 28 march to 22 april 1999 eruption of mount cameroon volcano in southwest cameroon occurred from multiple vents along fissures at two sites vents opened first at the upper site 1 2650 m and were more explosive than vents at the lower site 2 1500 m which were more effusive earthquakes lava flows tephra fall ballistics and gas emissions affected the volcano s west and south flanks including forests plantations stock animals water supplies coastal communities and their people through an analysis of existing published data and new interview data we provide an overview of the environmental social and economic consequences of these hazards on infrastructure human health and socio economic and agricultural activities of the four coastal communities most affected by the eruption batoke bakingili debundscha and idenau the collected data provide a more detailed description of the short and long term direct and indirect effects of the eruption and response than has been provided to date sedimentation of tephra and ballistics from site 1 produced both short term and long lasting impacts on people through the contamination of plants and water supplies which induced impacts on human health and commercial activities a 9 2 km long lava flow erupted from site 2 received significant short term attention as it severed the only arterial coastal highway forced the evacuation of some 600 residents of bakingili and interrupted commerce between communities the agricultural sector also suffered due to burning of crops and soils the only obvious significant benefit of the eruption appears to be that the long lava flow has become a tourist attraction responsible for bringing in money for food drink and lodging however the long term cascading effects caused by the hazards have proven to be more severe than the immediate direct and indirect effects during the eruption

buildings vs ballistics quantifying the vulnerability of buildings to volcanic ballistic impacts using field studies and pneumatic cannon experiments abstract recent casualties in volcanic eruptions due to trauma from blocks and bombs necessitate more rigorous ballistic specific risk assessment quantitative assessments are limited by a lack of experimental and field data on the vulnerability of buildings to ballistic hazards an improved quantitative understanding of building vulnerability to ballistic impacts is required for informing appropriate life safety actions and other risk reduction strategies we assessed ballistic impacts to buildings from eruptions at usu volcano and mt ontake in japan and compiled available impact data from eruptions elsewhere to identify common damage patterns from ballistic impacts to buildings we additionally completed a series of cannon experiments which simulate ballistic block impacts to building claddings to investigate their performance over a range of ballistic projectile velocities masses and energies our experiments provide new insights by quantifying 1 the hazard associated with post impact shrapnel from building and rock fragments 2 the effect of impact obliquity on damage and 3 the additional impact resistance buildings possess when claddings are struck in areas directly supported by framing components this was not well identified in previous work which may have underestimated building vulnerability to ballistic hazards to improve assessment of building vulnerability to ballistics we use our experimental and field data to develop quantitative vulnerability models known as fragility functions our fragility functions and field studies show that although unreinforced buildings are highly vulnerable to large ballistics 20 cm diameter they can still provide shelter preventing death during eruptions

volcanic ashfall accumulation and loading on gutters and pitched roofs from laboratory empirical experiments implications for risk assessment abstract volcanic ash load is dependent on the migration and accumulation of ash on roofing surfaces and guttering of which limited research has been conducted this study investigates this knowledge gap through the empirical experimental testing of volcanic ash on variably pitched metal sheet roofs with modern pvc gutter systems highlighting the relative importance of accumulation migration remobilization saturation and subsequent load a testing rig delivered ash onto variably pitched roofs pitches 15 25 30 35 and 45 with two 45 tests involving a wet surface with subsequent ashfall and the second of ashfall with periods of wetting followed by wetting until failure in testing dry ash on a dry roof accumulates at pitches up to 35 above this pitch the percentage of ash accumulating reduces with greater percentages infilling guttering and or lost to the ground with the introduction of a wet roof surface at 45 pitch adherence of dry ash greatly increases increasing accumulated ash thickness as compared to dry tests from 8 to 38 for testing involving periods of wetting at 45 roof pitch accumulation percentages further increased to 50 ash migrating from the roof surface filled guttering more rapidly at greater pitches which once full resulted in further migrating ash to spill over the front or back gutter lips collapse of guttering did not occur during testing but deformation and bracket detachment did occur at loads 1 kpa this study provides data on load calculations on roofing and pvc guttering through the quantification and utilization of relationships between ash fate pitch and the influence of water in the development of two scenarios for both roof and gutter these two scenarios then enable the estimation of ash accumulation and thus the load and collapse thresholds for roof and gutter at different roof pitch which could be adopted for volcanic risk modeling or risk management

potential impacts of tephra fallout from a large scale explosive eruption at sakurajima volcano japan we present an exposure analysis of infrastructure and lifeline to tephra fallout for a future large scale explosive eruption of sakurajima volcano an eruption scenario is identified based on the field characterization of the last subplinian eruption at sakurajima and a review of reports of the eruptions that occurred in the past six centuries a scenario based probabilistic hazard assessment is performed using the tephra2 model considering various eruption durations to reflect complex eruptive sequences of all considered reference eruptions a quantitative exposure analysis of infrastructures and lifelines is presented primarily using open access data the post event impact assessment of magill et al earth planets space 65 677 698 2013 after the 2011 vei 2 eruption of shinmoedake is used to discuss the vulnerability and the resilience of infrastructures during a future large eruption of sakurajima results indicate a main eastward dispersal with longer eruption durations increasing the probability of tephra accumulation in proximal areas and reducing it in distal areas the exposure analysis reveals that 2300 km of road network 18 km2 of urban area and 306 km2 of agricultural land have a 50 probability of being affected by an accumulation of tephra of 1 kg m2 a simple qualitative exposure analysis suggests that the municipalities of kagoshima kanoya and tarumizu are the most likely to suffer impacts finally the 2011 vei 2 eruption of shinmoedake demonstrated that the already implemented mitigation strategies have increased resilience and improved recovery of affected infrastructures nevertheless the extent to which these mitigation actions will perform during the vei 4 eruption presented here is unclear and our hazard assessment points to possible damages on the sakurajima peninsula and the neighboring municipality of tarumizu

precariously balanced rocks and ground motion maps for southern california groups of precariously balanced rocks are effectively low resolution strong motion seismoscopes that have been operating on solid rock outcrops for thousands of years and once the methodology has been developed can provide important information about seismic risk in one zone near victorville only 30 km from the nearest point on the san andreas fault more than 50 precarious rocks have been documented widespread rock varnish suggests that many of these rocks have been in their current unstable positions for thousands of years we have established the mechanical basis for rough estimates of the horizontal accelerations necessary to topple these rocks using field observations and numerical and physical modeling to verify that zones of precarious rocks do not occur near historic earthquakes searches using binoculars were made along roads with occasional foot surveys near large earthquakes based on these reconnaissance searches we conclude that no precarious rock zones are found within 15 km of zones of high energy release of historic large earthquakes to document the occurrence of precarious rocks in southern california road surveys were carried out along major roads four zones of precarious rocks and seven other zones of somewhat less precarious rocks have been documented published probabilistic ground motion maps for southern california are compared with the occurrence of zones of precarious and semi precarious rocks the results are encouraging and suggest that eventually studies of precarious rocks will provide important constraints on the assumptions on which the maps are based results from studies of precarious rocks may eventually provide important information for siting and design of sensitive structures such as hospitals and power plants precarious rocks give a direct indication of past ground shaking in contrast to the indirect inference provided by fault trenching studies which may be subject to uncertainties in the actual time history of slip due to the fault e g fault creep slow earthquakes or unknown dynamic stress drop it is concluded that precarious rocks warrant further study and quantitative analysis

sediment production and delivery from recent large landslides and earthquake induced rock falls in the upper soca river valley slovenia abstract landsliding not only changes the morphology of the terrain but is also an effective factor in sediment production extreme events such as earthquake induced large rock falls or rainfall induced landslides may during the event itself or in a period after it greatly increase the sediment delivery and river sediment transport the effects of strong earthquakes and large landslides on sedimentation are evident in the upper soca river basin nw slovenia the annual sediment production in the headwaters of this typical alpine valley in western slovenia is estimated to average 1000 m 3 km 2 a 1 in the last few years two large landslides triggered there were of comparable volume but differed regarding sediment delivery to the fluvial network the 2000 sto e landslide at 1 5 million m 3 was a debris flow that delivered more than 1 million m 3 to the koritnica river the strug complex landslide was initiated in 2001 by a rock slide and soon amounted to an estimated volume of 310 000 m 3 in 2002 it released over 20 rainfall induced debris flows on the order of 100 to 1000 m 3 to the fluvial system in mountainous terrain in the headwaters of the upper soca river slope failures may occur during strong earthquakes depending on the event magnitude the earthquake of april 12 1998 m s 5 6 caused more than 100 failures among them 50 rock falls about 260 000 m 3 of rock fall material will remain on hill slopes with no potential of reaching the river network while an estimated volume of 480 000 m 3 may be released to watercourses in a longer period during extreme events about 200 000 m 3 of rock fall debris was deposited in areas from where the material was released to watercourses during rainfall events as a consequence of the 1998 earthquake hyperconcentrated flows were observed during floods in some torrential tributary channels of the upper soca river after the earthquake of july 12 2004 m s 4 9 50 rather superficial slope failures including 38 rock falls were registered from 2000 until 2004 more than 150 000 m 3 sediments were dredged from the upper soca river channel

earthquake triggering of landslides in highly jointed rock masses reconstruction of the 1783 scilla rock avalanche italy abstract the scilla rock avalanche occurred on 6 february 1783 along the coast of the calabria region southern italy close to the messina strait it was triggered by a mainshock of the terremoto delle calabrie seismic sequence and it induced a tsunami wave responsible for more than 1500 casualties along the neighbouring marina grande beach based on subaerial and submarine surveys a 5 106 m3 subaerial landslide was identified together with a 3 106 m3 submarine scar area whereas block deposits are present in both the subaerial and submerged regions a detailed geological reconstruction of the slope was obtained and a geomechanical characterisation of the metamorphic rocks involved in the landslide was performed based on this reconstruction intense jointing conditions of the rock mass can be related to main fault zones parallel and normally oriented to the actual coastline an engineering geology model of the landslide was devised according to an equivalent continuum approach to evaluate both stiffness and strength of the rock mass within the slope a finite difference stress strain numerical modelling of the scilla landslide was performed under dynamic conditions to back analyse the landslide trigger as well as local seismic amplifications this modelling gave new insights into the physical interactions between seismic inputs and slopes as it demonstrated the fundamental role played by i the interaction between the seismic input and geological setting of unsheared rock slopes i e without preexisting landslide masses ii cumulated strain effects due to seismic sequences and iii jointing conditions of the involved rock masses responsible for the seismic amplification of the landslide prone volume driving it toward failure conditions

earthquake induced rockfall hazard zoning abstract a methodology for quantitative probabilistic hazard zonation for earthquake induced rockfalls is presented and demonstrated in the area of friuli eastern italian alps affected by the 1976 mw 6 5 earthquake four rockfall datasets have been prepared both from historical data analysis and field surveys the methodology relies on a three dimensional hazard vector whose components include the rockfall kinetic energy the fly height and the annual frequency the values of the first two components are calculated for each location along the slope using the 3d rockfall runout simulator hy stone the rockfall annual frequency is assessed by multiplying the annual onset frequency by the simulated transit frequency the annual onset frequency is calculated through a procedure that combines the extent of unstable areas calculated for 10 different seismic hazard scenarios with different annual frequencies of occurrence and the magnitude relative frequency relationship of blocks as derived from the collected field data for each annual frequency of occurrence the unstable area is calculated as a function of morphometric and earthquake characteristics a series of discriminant analysis models using the rockfall datasets and dems of different resolution 1 and 10 m identified the controlling variables and verified the model robustness in contrast with previously published relationships we show that the slope curvature plays a relevant role in the computation of the unstable area

magma derived co2 emissions recorded in and content of plants growing in furnas caldera azores abstract the environmental impact of fumarolic and soil emanations of magma derived carbon dioxide across furnas caldera has been investigated by measuring the 14 c and 13 c content of 40 specimens of different c3 plants leaves growing within and outside the degassing areas the results demonstrate a significant to large 14 c depletion in many of the plants due to assimilation of 14 c free endogenous co2 during photosynthesis and leading to artificial radiocarbon ageing of up to 4400 years the extent of 14 c ageing broadly correlates with the intensity of gas manifestations at the sampling sites as inferred from field observations and measurements of excess co2 concentrations in the volcanic ground it also provides a time integrated measure of the amount of volcanic co2 locally admixed to the ambient air at several sites this accounts for 15 to 40 of total co2 420 to 600 ppm in enriched air in some of the plant species azalea camellia and fern 14 c depletion is correlated with an enrichment of 13 c due to assimilation of magma derived co2 with a 4 higher 13 c than normal atmosphere the rate of 13 c enrichment averages ca 0 18 by percent of volcanic carbon fixed in the plant and includes enhanced 13 c discrimination during photosynthesis as a consequence of increased ambient pco2 inferred at 0 0306 per added ppm of volcanic co2 furnas is one of the few volcanoes where clear 13 c enrichment in plants due to endogenous degassing has been evidenced our results can be used to estimate the local intensity of volcanic soil gas fluxes in the emanating areas of furnas caldera they also have implications for radiocarbon dating of past eruptive events in the caldera since plants artificially aged by previous degassing could be trapped in volcanic deposits

human vulnerability in volcanic environments the case of furnas sao miguel azores abstract the need to examine the vulnerability of people to natural hazards in addition to the long established requirement to study extreme events of nature is being increasingly recognised within disaster research following a discussion of the nature of human vulnerability we propose a framework for its analysis within the context of volcanic activity and we exemplify our approach by a detailed study of furnas a village located at the centre of a volcano with the same name on the island of sao miguel in the azores the methods used included in depth interviews with permanent residents n 50 analysis of census records and an examination of the socio economic history of the town the vulnerability of an individual to volcanic hazards involves a complex interaction of elements which in addition to the usual factors taken into account in programmes of hazard reduction e g the nature of the physical threat location and economic situation also comprises his or her social context and a number of physiological and psychological considerations it is argued further that both generally and in the case of furnas the root causes of vulnerability lie in the history and development of society individual decision making is fundamental but takes place within and cannot be separated from this social context vulnerability analysis allows the identification of points where intervention may be successful in reducing the likelihood of suffering in a society it avoids the problem of people s unexpected reactions to invention leading to a changing or even increasing level of vulnerability by studying society rather than just one aspect of volcanic hazard in isolation

impact resistance to ballistic ejecta of wooden buildings and a simple reinforcement method using aramid fabric abstract many of the casualties in the phreatic eruption of mt ontake which is located in central japan on september 27 2014 were climbers near the summit the main cause of death was injury by lapilli and block ejecta ballistic ejecta the absence of shelters at the summit and along the climbing trails may be a major factor in the large number of casualties attributable to ballistic ejecta and establishing and improving shelters on active volcanoes is an urgent need the climbers who evacuated to wooden mountain huts survived the 2014 mt ontake eruption this research focuses on the impact characteristics of wooden materials we therefore performed an experimental investigation into the safety of wooden materials under impact by simulated ballistic ejecta with a mass of 2 66 kg equivalent to a diameter of 128 mm as by assembling cylindrical abrasive travelling at up to 300 km h approximately 83 m s with abrasives acting as ballistic ejecta the simulated shelter facility components serving as targets were wooden structures composed of japanese cedar which found on volcanoes at high elevations in japan the components of the fabricated roof were japanese cedar with a thickness of 15 mm as roofboard installed on the surface waterproof sheet and 0 4 mm thick galvalume steel sheet with an additional rafter installed the impact absorption energy of the fabricated roof increased with simulated ballistic ejecta impact velocity because the localization of bending deformation progressed at the impact part and the frequency of splitting failure increased with increasing impact velocity this is attributable to variation in the mode of splitting failure of cedar boards and the dependence of the material strength on projectile velocity we also experimentally investigated simple reinforcement methods in order to obtain basic data on conversion of mountain huts to shelters the reinforced wooden structure could withstand simulated ballistic ejecta impacts of up to approximately 13 kj by incorporating two layers of aramid fabric between a waterproof sheet and a cedar board review of the roof structures of existing wooden buildings based on these results promises further advances in safe impact resistant design

palaeoseismicity in the gran sasso massif abruzzo central italy abstract the upper maone and venacquaro valleys on the northern side of the gran sasso massif apennines central italy have been studied in detail from the geological and geomorphological standpoints to date the activity of the faults that produced spectacular fault scarps in the late glacial and holocene sediments and morphological features the faults that produced the studied scarps have been active at least four times during the last 18 000 years and each time on the basis of the indications emerging from the study of the scarp heights displacements of similar size were probably produced the first faulting seems datable to a period slightly more recent than 18 000 years ago the second faulting occurred after the moraines of the second apennine stage these preceding a lacustrine deposit dated 11 760 160 bp could be put in the older portion of the period between 16 000 and 13 000 years ago the third faulting must be more recent than 6000 7000 years ago and slightly older than 5450 170 and 6110 180 bp a fourth phase is appreciably later than 3490 160 bp and older than the year 1000 a d for the venacquaro valley the size of the displacements more recent than 18 000 years ago indicated by the height of the fault scarps and by geophysical data is about 16 18 m for the val maone the size of the displacements more recent than the moraines of the second apennine stage is 10 11 m the respective slip rates are 0 88 1 mm year for the venacquaro valley and approximately 0 67 0 78 mm year for the maone valley it is very probable that the fault activity occurred during a seismic event or events that took place during a short time the intervals between the seismic events or seismic periods although these cannot be defined with precision appear longer than 2500 3000 years and shorter than 6000 7000 years it is possible that also in the gran sasso as in other parts of the abruzzo apennines seismic activity is characterized by events of great magnitude with long return periods

responses of an arctic landscape to lateglacial and early holocene climatic changes the importance of moisture many of the physical and biological processes that characterize arctic ecosystems are unique to high latitudes and their sensitivities to climate change are poorly understood stratigraphic records of land surface processes and vegetation change in the arctic foothills of northern alaska reveal how tundra landscapes responded to climatic changes between 13 000 and 8000 14 c yr bp peat deposition began and shrub vegetation became widespread ca 12 500 14 c yr bp probably in response to the advent of warmer and wetter climate increased slope erosion caused rapid alluviation in valleys and populus trees spread northward along braided floodplains before 11 000 14 c yr bp lake levels fell and streams incised their floodplains during the younger dryas yd 11 000 10 000 14 c yr bp a hiatus in records of populus suggest that its geographic range contracted and pollen records of other species suggest a cooler and drier climate during this interval basal peats dating to the yd are rare suggesting that rates of paludification slowed immediately after 10 000 14 c yr bp lake levels rose streams aggraded rapidly again intense solifluction occurred and populus re invaded the area moist acidic tundra vegetation was widespread by 8500 14 c yr bp along with wet organic rich soils most of these landscape scale effects of climatic change involved changes in moisture although low temperature is the most conspicuous feature of arctic climate shifts in effective moisture may be the proximate cause for many of the impacts that climate change has in arctic regions r 2002 elsevier science ltd all rights reserved

groundwater recharge estimation using chloride stable isotopes and tritium profiles in the sands of northwestern senegal a study of environmental chloride deuterium oxygen 18 and tritium in deep sand profiles 35 m has been carried out in order to estimate their relative value for measuring average groundwater recharge the investigation was located at a 0 1 km2 site in quaternary sands near the northwestern coast of senegal in a zone of rainfed agriculture by using a steady state model for duplicate unsaturated zone chloride profiles the long term average recharge at the site was estimated to be 30 mm yr 1 or around 10 of the average precipitation 290 mm the chloride concentration of adjacent shallow groundwater was relatively uniform and comparable to the unsaturated zone average while the spatial variability in the depth distribution of cl in the unsaturated zone was considerable stable isotope deuterium and oxygen 18 data show that there is some isotopic enrichment due to direct evaporation through the soil surface the degree of heavy isotope enrichment is proportional to the extent of evaporative loss and there is good correspondance with the chloride enrichment nevertheless stable isotopes cannot be used quantitatively to estimate the recharge the excellent preservation of the peak in thermonuclear tritium in precipitation in the unsaturated zone at depths between 12 and 20 m enables an estimated annual recharge of 24 mm yr 1 in this area to be calculated using the piston flow model agreement therefore between cl and3h as tools for recharge measurement is reasonable over the site

source mechanism of volcanic earthquakes a description and classification of seismic sources found in active zones of volcanism are given the main sources of seismic wave energy are caldera collapse shear fractures with comparatively low spectral corner frequencies shallow gas explosions hydraulic pressure transients and non stationary magma flew

estimation of groundwater recharge in weathered basement aquifers southern zimbabwe a geochemical approach abstract geochemical techniques have been used to estimate groundwater recharge and its spatial variability in basement terrain in a semi arid area of southern zimbabwe recharge rates estimated by chloride mass balance have been determined in the romwe catchment a small 4 6 km2 headwater catchment underlain by banded gneisses with good hydrological and geological control the results support the findings from piezometric monitoring that there are significant differences in hydrogeological properties of weathered basement derived from different primary lithologies annual recharge estimates for shallow weathered aquifers derived from melanocratic bedrock dominated by pyroxene gneiss 22 mm and leucocratic felsic bedrock 6 7 mm are 3 7 and 1 1 respectively of the long term mean annual rainfall the significant uncertainties associated with the chloride mass balance recharge estimates are discussed groundwater derived from each lithology generally has a distinctive geochemistry na cl k na mg ca na cl b ba the information from the romwe catchment control area was then scaled up using information from remote sensing images which defined areas of dark and light soils above the banded gneiss to confirm the higher recharge rates in the melanocratic lithology in the unexplored greater romwe 225 km2 area it is concluded that properly calibrated remote sensing images could be further regionalized to site groundwater sources in basement terrain providing a relatively inexpensive development tool

a model for wet aggregation of ash particles in volcanic plumes and clouds 2 model application 1 the occurrence of particle aggregation has a dramatic effect on the transport and sedimentation of volcanic ash the aggregation process is complex and can occur under different conditions and in multiple regions of the plume and in the ash cloud in the companion paper costa et al develop an aggregation model based on a fractal relationship to describe the rate particles are incorporated into ash aggregates the model includes the effects of both magmatic and atmospheric water present in the volcanic cloud and demonstrates that the rate of aggregation depends on the characteristics of the initial particle size distribution the aggregation model includes two parameters the fractal exponent df which describes the efficiency of the aggregation process and the aggregate settling velocity correction factor e which influences the distance at which distal mass deposition maxima form both parameters are adjusted using features of the observed deposits here this aggregation model is implemented in the fall3d volcanic ash transport model and applied to the 18 may 1980 mount st helens and the 17 18 september 1992 crater peak eruptions for both eruptions the optimized values for df 2 96 3 00 and e 0 27 0 33 indicate that the ash aggregates had a bulk density of 700 800 kg m 3 the model provides a higher degree of agreement than previous fully empirical aggregation models and successfully reproduces the depositional characteristics of the deposits investigated over a large range of scales including the position and thickness of the secondary maxima

development of volcanic insular shelves insights from observations and modelling of faial island in the azores archipelago a variety of geological processes contribute to the development of volcanic island shelves although their relative importance remains unclear we have mapped the morphology of faial island s shelf in the azores from geophysical multibeam sonar chirp and boomer seismic reflection and geological data sediment sampling a wave erosional model and a eustatic record of glacially induced oscillations of sea level which modulated the elevation at which the waves operated through time was used to determine the contribution of mechanical wave erosion to shelf development wave regimes varied according to the orientation of the coast the model was run for 10 to 800 ka depending on the age of the various coastal sectors based on published radiometric data the modelling replicated the shape of the island s shelf reasonably well supporting the contention that it developed primarily through mechanical wave erosion operating in an intertidal zone that migrated landwards and seawards with changes in the level of the sea disparities between modelled and actual shelf morphologies may reflect varied geological resistance to erosion errors in the radiometric dates more recent unrecognised volcanic deposits sediment deposition and tectonic vertical movements there were some variation in rates of shelf development over different time scales but over the long term the relationship between shelf age and width was essentially linear the depth of the shelf break in some areas suggests that there have been differential vertical movements of the land around the island probably related to local faults the poor development or absence of terraces on the shelf may be attributed either to recent volcanic progradation or to sediment infilling of the space created by earlier erosion however poorly developed terraces on the southern shelf of faial are similar to those predicted by the model given appropriate adjustments for vertical movements of the land

evaluation of anfis and lr models for seismic rockfalls susceptibility mapping a case study of firooz abad kojour iran earthquake 2004 seismic rockfall is one of the prevalent geohazards that cause huge losses in the earthquake stricken areas in the present research a model is developed to map susceptibility occurrence probability of seismic rockfalls in a regional scale using logistic regression lr and adaptive neuro fuzzy inference system anfis techniques in this research firooz abad kojour earthquake of 2004 was introduced as the benchmark and the model base the susceptible zones predicted by lr and anfis methods were compared with the database distribution map of seismic rockfalls by which the results revealed a good overlapping between the susceptible zones predicted by the anfis and the field observation of rockfalls triggered by this earthquake besides for the statistical evaluation of results obtained by lr and anfis models the verification parameters with high accuracy such as density ratio dr quality sum qs and receiver operating characteristic curve roc were used by analyzing the susceptibility maps and considering the qs index obtained by lr 21 04184 and anfis 26 75592 it could be found that the qs of anfis is higher than that of lr moreover based on the obtained value of the area under the curve auc from lr 0 972 and anfis 0 984 methods anfis provided a higher accuracy in zonation and susceptibility mapping of rockfalls triggered by firooz abad kojour earthquake of 2004 compared to the lr method

the interest of cartography for a better perception and management of volcanic risk from scientific to social representations the case of mt pelee volcano martinique lesser antilles the study develops an innovative gis based integrated approach for the assessment of a comprehensive volcanic risk this is based on a four step methodology which has been developed at mt pelee volcano in martinique a french island in the lesser antilles the first stage of the methodological framework integrates the spatial extent of volcanic hazards for a maximal credible eruptive scenario the second stage covers an assessment of the elements especially the buildings that may be affected in the event of an eruption and defines their level of damages by given volcanic hazards a computerized analysis leads to the definition of an index for the risk of total loss in a 500 meter grid the third stage consists of designing regulative land use maps which should orient and limit the occupation of areas exposed to severe hazards finally the fourth stage based on survey data includes a spatial assessment of collective representations for a future eruption by the surrounding communities these maps turn out to be powerful communication tools which help planners and disaster authorities in mitigating damages from volcanic hazards they can contribute to enhance the perception of volcanic risk in martinique

seismic moment summation for historical earthquakes in italy tectonic implications tectonic deformation rates in and around the apennine mountains of italy are studied using seismic moments estimated from macroseismic effects of historical earthquakes northeastward extension in the northern apennines north of 42 5 n accompanies shortening along their northeast flank since the seventeenth century the sparse seismicity in these two zones has included no earthquake with magnitude 6 5 or seismic moment above 6 1018 n m their spatially averaged deformation rates are only 0 3 mm yr 1 but are equal such that the extension and shortening balance with no relative motion between their external surroundings in contrast the numerous historical earthquakes in the central and southern apennines with magnitude 7 and seismic moment 20 1018 n m require northeastward relative velocity across the deforming zone up to 5 mm yr 1 matching the expected relative motion of their surroundings this relative velocity is taken up in part by extension and in part by strike slip depending on the trend of the deforming zone and is not accompanied by en echelon shortening elsewhere in italy the northern apennines thus show different senses and rates of deformation from localities farther south and are thus technically distinct at present in contrast with previous interpretations

application of multi temporal differential interferometry to slope instability detection in urban peri urban areas abstract we present two case studies regarding the application of synthetic aperture radar sar persistent scatterers interferometry psi techniques to landslide prone slopes situated in the municipal territories of caramanico terme and volturino italy the analysis of satellite sar data with psi techniques poses often problems on sites where due to the scarcity of human artefacts and the presence of vegetation cover density of coherent points ps is low 2 moreover the steep and rough topography typical of landslide prone areas hamper the interferometric pre processing making more difficult the joint estimation of displacements and of dem errors under these conditions the significance of temporal interferometric phase trends can be uncertain and conservative assumptions necessary to ensure low false detection probabilities need to be coupled with innovative processing strategies to increase the detection efficiency of ps objects here the spinua stable point interferometry over un urbanised areas processing technique is applied together with an alternative ps candidate psc selection procedure based on the use of pixels classified as urban the cases of caramanico and volturino are representative respectively of harsh and favourable conditions for psi applications the results from caramanico show clusters of ps exhibiting similar line of sight los deformation behaviour in the period 1995 2000 the locations of moving ps often coincide with distressed buildings and appear consistent with the areal distribution of recent and past landslide activity the temporal displacement trends however are characterised by very low annual average velocities from 3 to 7 mm y and it is uncertain to what extent the ps data reflect true slope movements local deformations e g settlement of engineering structures or both thanks to the more favourable conditions the application of the standard spinua approach in the volturino area was sufficient to obtain suitable densities of ps as well as spatially and temporally consistent displacement results for a period 1992 2000 in particular a group of moving ps was identified in a peri urban area known for the past and recent slope stability problems the slowly moving ps from 3 to 5 mm y fall in a location that unlike the remaining part of the town is characterised by the presence of many distressed buildings and structures although the site information confirms the reliability of ps data in the absence of ground monitoring and detailed records of landslide movements it is difficult to identify the main mechanism of the detected deformations in general in geologically and topographically complex urban peri urban settings the significance of very low velocity psi surface displacements should always be considered together with in situ geotechnical controls and ground monitoring data

trench investigations of the 1915 fucino earthquake fault scarps abruzzo central italy geological evidence of large historical events earthquake hazard analyses in italy are mainly based on historical seismic catalogs however the completeness of the italian catalog which spans more than 2000 years progressivcly decreases going back in time in the fucino basin historical research has not produced evidence of large earthquakes before the january 13 1915 event m s 7 0 33 000 people killed this event generated surface faulting along at least two parallel quaternary normal faults bounding the eastern side of the basin the celano gioia and parasano cerchio faults over an end to end length of about 23 km with a downthrow of 30 90 cm toward southwest to improve geological aspects of the seismic history of this area we trenched onc of the coseismic scarps along the celano gioia fault at a trench site near the village of san benedetto de marsi the fault traverses the area formerly covered by the fucino lake drained for farming in 1875 a d the evidence collected in the trenchcs suggests at least two large events in historical times before 1915 radiocarbon dates constrain the age of event b between the 6th and the 9th centuries a d possibly coinciding with the cvent felt in rome in 801 a d molin arid guidoboni 1989 event a probably occurred after the 10th ccntury a d and almost certainly before the 1349 a d earthquake because historical studies show 1 that event a was not produced during the earthquake sequence that occurred in central italy in 1349 a d molin and guidoboni 1989 and 2 that the post 1349 seismic catalog can be regarded as complete for surface faulting earthquakes surface displacements determined for events a and b compared to the 1915 surface faulting indicate that m 6 5 earthquakes were associated with each rupturc these obscrvations suggest that the return period for large earthquakes in the fucino basin is shorter than that indicated by the historical record alone the fucino example clearly shows that thc cxceptionally long historical record in italy is still inadequate for a comprehcnsive seismic hazard characterization

advances and problems in understanding the seismic response of potentially unstable slopes abstract the influence of site effects on landslide triggering during earthquakes has been inferred in several studies but its evaluation is made difficult by the complexity of factors controlling the dynamic response of potentially unstable slopes and also by the lack of local ground motion instrumental observations this work explores this problem and reports new findings based on an ongoing long term accelerometric monitoring conducted on a landslide prone test area in the apennine mountains italy where the presence of site effects enhancing seismic susceptibility of local slopes has been invoked on the basis of historic accounts of landsliding triggered at large epicentral distance the recordings relative to low to moderate magnitude earthquakes showed significant amplifications affecting hillslope portions covered by thick 5 m colluvia and pronounced amplification maxima oriented along the local maximum slope direction on a recent deep seated landslide while the amplifications seem most likely linked to high impedance contrast between surface materials and underlying substratum the causes of directivity are less clear the case of the monitored test site together with evidence of site response directivity identified on other hillslopes suggest that the directivity phenomena can result from a combination of topographic lithological and structural factors that act together to re distribute shaking energy focusing it on site specific directions thus it is difficult to single out the critical factors controlling such phenomena and no general criterion for the identification of sites affected by directivity is proposed here nevertheless the presence and orientation of site response directivity can be revealed through reconnaissance techniques by using recordings of seismic weak motion and or ambient microtremors and calculating azimuthal variation of shaking energy and horizontal to vertical ground motion spectral ratios a comparison with the recordings obtained during the recent m w 6 3 earthquake that hit the abruzzo region in april 2009 demonstrated that analysis relying on data from low energy events can furnish valid indications for slope behaviour also under stronger shaking provided the data are well differentiated in terms of distance azimuth and source characteristics furthermore the comparative analysis of the abruzzo earthquake recordings at a landslide and reference sites showed that directivity properties of strong shaking had been correctly anticipated using earlier weak motion observations however under the complex slope conditions the identification of resonance frequencies from horizontal to vertical spectral ratios estimated from weak motion accelerometric recordings does not seem reliable and better results have been obtained by velocimetric microtremor recordings

multiple meltwater discharge and ice rafting events recorded in the deglacial sediments along the beaufort margin arctic ocean abstract the first regional model for the deglacial history of the beaufort margin slope in the western arctic is presented the conceptual model was developed using new high resolution chirp seismic reflection multibeam bathymetry and sediment core data acquired along the margin this synthesis provides important constraints on sediment source and dispersal patterns for the last deglaciation the continental slope from barrow canyon to the mackenzie trough is characterized by thick holocene sediments mostly sourced from barrow canyon and continental discharge this acoustically transparent fine grained unit overlies acoustically laminated sediments sourced from the mackenzie river and ice rafting the deglacial history of the margin from mackenzie trough to the amundsen gulf is characterized by many ice rafting and meltwater discharge events ice rafted debris layers were deposited around 14 6 ka and 14 1 ka and likely document enhanced ice shedding events from the amundsen and m clure ice streams as they retreated there are three inferred meltwater discharge events all sourced from the mackenzie region the oldest discharge event had two phases one sometime between 14 5 ka and 14 2 ka and another between 14 0 ka and 13 0 ka this discharge deposited finely laminated sediments more than 7 m thick sourced from proglacial lakes in the area following this was a flood event starting at 12 94 ka which generated high amplitude reflectors deposited coarse debris and caused a lowering in the 18o record this is possibly a major outburst flood from glacial lake agassiz with an additional component of agassiz meltwater that was diverted from its southern drainage pathway down the mississippi to the gulf of mexico finally a third discharge event was initiated by 11 3 ka which deposited coarse laminated sediments focused in the mackenzie trough timing of these second and third events correlates with the onset of the younger dryas cold period and the preboreal oscillation event respectively suggesting that fresh water discharge may have reached a tipping point leading to those climate events

data for enhanced deposition of coal fragments at the chukchi margin western arctic ocean implications for deglacial drainage history from the laurentide ice sheet abstract distribution and composition of coarse particles 250 m were investigated in 13 sediment cores from the chukchi margin western arctic ocean petrographic clast identification is supplemented by xrf core scanning eds analysis of coal fragments and ams 14c dating of planktic foraminifera for age control coal debris distribution is also investigated in surface sediments of the study region for provenance interpretation the sediment core study focuses on the interval between the last glacial maximum and the holocene for constraining provenance and timing of the deglacial discharge we find that this interval is characterized by a distinct enrichment in sedimentary rock fragments including coal comparison with longer stratigraphic records indicates that this composition is unique for the time interval since at least maine isotope stage 5 based on the timing interpreted provenance and geographic distribution of the coal enrichment we conclude that the most likely primary source was the deglacial discharge from the mackenzie drainage basin of the laurentide ice sheet lis the identified coal bearing layer also expressed in the xrf sulfur record can be thus used as a stratigraphic marker for the lis discharge to the arctic ocean during the last deglaciation

response to grosswald and hughes 2004 brigham grette et al 2003 chlorine 36 and 14c chronology support a limited last glacial maximum across central chukotka northeastern siberia and no beringian ice sheet and gualtieri et al 2003 pleistocene raised marine deposits on wrangel island northeastern siberia implications for arctic ice sheet history

iceberg discharge to the chukchi shelf during the younger dryas abstract the extent of glaciation in northwestern alaska the source of sediment supply to the chukchi shelf and slope and the movement of sea ice and icebergs across the shelf during the last glacial maximum lgm remain poorly constrained here we present geophysical and geological data from the outer chukchi margin that reveal a regionally extensive heavily ice scoured surface 5 8 m below the modern seafloor radiocarbon dating of this discrete event yields age estimates between 10 600 and 11 900 14c yr bp indicating the discharge event occurred during the younger dryas based on mineralogy of the ice rafted debris the icebergs appear to be sourced from the northwestern alaskan margin which places important constraints on the ice extent in northern alaska during the lgm as well as existing circulation models for the region

an approach to time probabilistic evaluation of seismically induced landslide hazard the need for effective strategies for preventing and mitigating damage caused by earthquake induced landslides has stimulated recent developments of techniques for the assessment of seismic landslide exposure at a regional scale however for a rational risk management a crucial element is represented by the time horizon of the hazardous events a new way to incorporate the time factor in seismic landslide hazard assessment is proposed here it consists of evaluating the temporal recurrence of seismically induced slope failure conditions inferred from the newmark s model first by adopting arias intensity to quantify seismic shaking well established methods of seismic hazard assessment are employed to obtain the occurrence probabilities for different levels of seismic shaking in a time interval of interest then some empirical relations based on the newmark s model are employed to evaluate the slope critical acceleration a c for which a prefixed probability exists that seismic shaking would result in landslide triggering the obtained a c values represent the minimum slope resistance required to keep the probability of seismic landslide triggering within the prefixed value therefore the space distribution of the calculated a c values can be promptly compared with the actual in situ a c values of specific slopes to estimate whether these slopes have a significant probability of failing under seismic action in the future an example of this approach applied to an area in southern italy daunia region shows that the introduction of the time factor significantly modifies the representation of the spatial hazard and allows evaluation of the relevance of seismicity as a landslide triggering agent

volcanic geology of furnas volcano sao miguel azores abstract furnas is the easternmost of the three active central volcanoes on the island of sao miguel in the azores unlike the other two central volcanoes sete cidades and fogo furnas does not have a well developed edifice but consists of a steep sided caldera complex 8 5 km across it is built on the outer flanks of the povoacao nordeste lava complex that forms the eastern end of sao miguel constructive flanks to the volcano exist on the southern side where they form the coastal cliffs and to the west the caldera margins tend to reflect the regional local tectonic pattern which has also controlled the distribution of vents within the caldera and areas of thermal springs activity at furnas has been essentially explosive erupting materials of trachytic composition products associated with the volcano include plinian and sub plinian pumice deposits ignimbrites and surge deposits phreatomagmatic ashes block and ash deposits and dome materials most of the activity has occurred from vents within the caldera or on the caldera margin although strombolian eruptions with aa flows of ankaramite and hawaiite have occurred outside the caldera the eruptive history consists of at least two major caldera collapses followed by caldera infilling based on 14 c dates it appears that the youngest major collapse occurred about 12 000 10 000 years bp new 14 c dates for a densely welded ignimbrite suggest that a potential caldera forming eruption occurred at about 30 000 years bp recent eruptions

new perspectives on beringian quaternary paleogeography stratigraphy and glacial history abstract aspects of the paleogeography stratigraphy and glacial history of beringia have been greatly revised over the past 15 20 yr access to north east russia in particular has provided the opportunity to evaluate the beringia landscape as a contiguous subcontinent during the quaternary for the first time new research has made clearer the connection between tectonic forces and the submergence of the bering strait during the middle pliocene revisions in the regional stratigraphy of glacial and interglacial deposits in northwest alaska and northeast russia provide a new foundation for assessing the causes for differences in glacial ice extent through time the consensus of all field workers verifies that glacial ice throughout most of beringia was of very limited extent during the last glacial maximum the onset of regional glaciation during the waning stages of the last interglaciation is clearly out of phase with glaciation at lower latitudes despite the lack of much glacial activity during the early holocene alaska contains a rich record of late holocene glacial response to neoglacial cooling changes in the holocene environment of beringia likely had a profound affect on early inhabitants the curiosity driven vision and spirit of both david hopkins and the late troy pewe have had a profound influence on arctic paleoenvironmental research

rocking and overturning of precariously balanced rocks by earthquakes abstract precariously balanced rocks in seismically active regions may be used to provide constraints on probabilistic estimates of strong ground motion a computer program is developed to study the rocking response of models of precariously balanced rocks when subjected to various levels of ground accelerations the computer code validated by comparing the numerical and experimental results for simple shaped rigid blocks is used to study the rocking response of rectangular blocks with various aspect ratios to the el centro strong ground motion recording of the 18 may 1940 imperial valley earthquake results show that during earthquakes the horizontal components of ground motion play a dominant role in overturning rocking objects the rederived and corrected housner9s equation 1963 could be used to estimate the minimum overturning acceleration of precarious rocks at different frequencies by measuring the quasi static toppling acceleration in the field

new evidence for high discharge to the chukchi shelf since the last glacial maximum using chirp subbottom profiling across the chukchi shelf offshore nw alaska we observed a large incised valley that measures tens of kilometers in width the valley appears to have been repeatedly excavated during sea level lowering however the two most recent incisions appear to have been downcut during the last sea level rise suggesting an increase in the volume of discharge modern drainage from the northwestern alaskan margin is dominated by small low discharge rivers that do not appear to be large enough to have carved the offshore drainage the renewed downcutting and incision during the deglaciation and consequent base level rise implies there must have been an additional source of discharge paleoprecipitation during deglaciation is predicted to be at least 10 less than modern precipitation and thus cannot account for the higher discharge to the shelf glacial meltwater is the most likely source for the increased discharge

lakes groundwater and palaeohydrology in the sahel of ne nigeria evidence from hydrogeochemistry the geochemistry of natural waters from rain soil the unsaturated zone shallow aquifers lakes and the stratified aquifer system of the chad basin sediments has been investigated to interpret modern hydrological processes and to reconstruct the palaeohydrology of ne nigeria a type region of the southern sahel recharge to the confined middle and lower aquifers recorded in ne nigeria occurred between 24 and 18 6 ka bp prior to the last glacial maximum the mean annual temperature at this time derived from dissolved noble gas ratios was at least 6 c cooler than at the present day this groundwater is not coupled to the active modern recharge cycle and was not reactivated during the holocene wet phases as elsewhere in the saharan region a reflection of changing lake levels and or of changing climatic regimes the absence of groundwater recharge at the time of the last glacial maximum supports other evidence for aridity at this time present day direct recharge rates in the manga grasslands are high mean 44 mm a 1 however regional recharge in ne nigeria at the present day is even higher 60 mm a 1 emphasizing the importance of infiltration from surface runoff as input to groundwater the present study confirms that the shallow aquifer in the region contains significant renewable groundwater resources however the confined aquifer of the chad basin clearly contains palaeowater and this declining artesian basin will need careful conservation prior to a return to traditional water use methods via improved management of the renewable waters in the shallow phreatic aquifers

magnitude and frequency in proglacial rivers a geomorphological and sedimentological perspective abstract proglacial fluvial sedimentary systems receive water from a variety of sources and have variable discharges with a range of magnitudes and frequencies little attention has been paid to how these various magnitude and frequency regimes interact to produce a distinctive sedimentary record in modern and ancient proglacial environments this paper reviews the concept of magnitude and frequency in relation to proglacial fluvial systems from a geomorphic and sedimentary perspective rather than a hydrological or statistical perspective the nature of the meltwater inputs can be characterised as low magnitude high frequency primarily controlled by ablation inputs from the source glacier or high magnitude low frequency primarily controlled by exceptional inputs the most important high magnitude low frequency inputs are catastrophic outburst floods often referred to by the term jokulhlaup icelandic for glacier burst glacier surges are an additional form of cyclical variation impacting the proglacial environment which briefly alter the volumes and patterns of meltwater input the sedimentary consequences of low magnitude high frequency discharges are related to frequent variations in stage the greater directional variability that sediment will record and the increased significance of channel confluence sedimentation in contrast the most significant characteristics of high magnitude low frequency flooding include the presence of large flood bars and mid channel jokulhlaup bars hyperconcentrated flows large gravel dunes and the formation of ice block kettle hole structures and rip up clasts glacier surges result in a redistribution of low magnitude high frequency processes and products across the glacier margin and small floods may occur at the surge termination criteria for distinguishing magnitude and frequency regimes in the proglacial environment are identified based on these major characteristics studies of quaternary proglacial fluvial sediments are used to determine how the interaction of the various magnitude and frequency regimes might produce a distinctive sedimentary record consideration of sandur architecture and stratigraphy shows that the main controls on the sedimentary record of proglacial regions are the discharge magnitude and frequency regime sediment supply the pattern of glacier advance or retreat and proglacial topography a model of sandur development is suggested which shows how discharge magnitude and frequency in combination with sandur incision and aggradation controlled by glacier advance and retreat can control sandur stratigraphy

geological controls on the geometry of incised valley fills insights from a global dataset of late quaternary examples incised valleys that develop due to relative sea level change are common features of continental shelves and coastal plains assessment of the factors that control the geometry of incised valley fills has hitherto largely relied on conceptual experimental or numerical models else has been grounded on case studies of individual depositional systems here a database driven statistical analysis of 151 late quaternary incised valley fills has been performed the aim being to investigate the geological controls on their geometry results of this analysis have been interpreted with consideration of the role of different processes in determining the geometry of incised valley fills through their effect on the degree and rate of river incision and on river size and mobility the studied incised valley fills developed along active margins are thicker and wider on average than those along passive margins suggesting that tectonic setting exerts a control on the geometry of incised valley fills likely through effects on relative sea level change and river behaviour and in relation to distinct characteristics of basin physiography water discharge and modes of sediment delivery valley fill geometry is positively correlated with the associated drainage basin size confirming the dominant role of water discharge climate is also inferred to exert a potential control on valley fill dimensions possibly through modulations of temperature peak precipitation vegetation and permafrost which would in turn affect water discharge rates of sediment supply and valley margin stability shelves with slope breaks that are currently deeper than 120 m contain incised valley fills that are thicker and wider on average than those hosted on shelves with breaks shallower than 120 m no correlation exists between valley fill thickness and present day coastal prism convexity which is measured as the difference in gradient between lower coastal plains and inner shelves these findings challenge some concepts embedded in sequence stratigraphic thinking and have significant implications for analysis and improved understanding of source to sink sediment route ways and for attempting predictions of the occurrence and characteristics of hydrocarbon reservoirs

volcanic risk assessment quantifying physical vulnerability in the built environment abstract this paper presents structured and cost effective methods for assessing the physical vulnerability of at risk communities to the range of volcanic hazards developed as part of the mia vita project 2009 2012 an initial assessment of building and infrastructure vulnerability has been carried out for a set of broadly defined building types and infrastructure categories with the likelihood of damage considered separately for projectile impact ash fall loading pyroclastic density current dynamic pressure and earthquake ground shaking intensities in refining these estimates for two case study areas kanlaon volcano in the philippines and fogo volcano in cape verde we have developed guidelines and methodologies for carrying out physical vulnerability assessments in the field these include identifying primary building characteristics such as construction material and method as well as subsidiary characteristics for example the size and prevalence of openings that may be important in assessing eruption impacts at risk buildings around kanlaon were found to be dominated by timber frame buildings that exhibit a high vulnerability to pyroclastic density currents but a low vulnerability to failure from seismic shaking around fogo the predominance of unreinforced masonry buildings with reinforced concrete slab roofs suggests a high vulnerability to volcanic earthquake but a low vulnerability to ash fall loading given the importance of agriculture for local livelihoods around kanlaon and fogo we discuss the potential impact of infrastructure vulnerability for local agricultural economies with implications for volcanic areas worldwide these methodologies and tools go some way towards offering a standardised approach to carrying out future vulnerability assessments for populated volcanic areas

widespread multi source glacial erosion on the chukchi margin arctic ocean abstract multibeam bathymetry and sub bottom profiler data acquired in 2011 from r v marcus langseth in a broad grid over the chukchi sea margin reveal multiple glacigenic features on the top and slopes of the outer chukchi shelf rise and adjacent borderland glacial lineations record a complex pattern of erosion likely formed by both local glaciation and far traveled ice shelves streams sourced from the laurentide and possibly east siberian ice sheets multiple till units and stacked debris flows indicate recurrent glacial grounding events composite till wedges of several hundred meters thick extend the shelf edge by 10 20 km in places distribution of ice marginal features on the chukchi rise suggests stepwise deglacial retreat towards the shelf backing up the broad bathymetric trough at the eastern side of the rise glacigenic features other than extensive iceberg scouring cannot be identified above 350 m depth and no glacigenic bedforms are present on the current swept shallow shelf despite the resulting uncertainty with the southern extent of the glaciation the data suggest a widespread grounded ice presence on the northern chukchi shelf which makes it an important previously underestimated component of the arctic paleo glacial system

rapid sea level rise and holocene climate in the chukchi sea three new sediment cores from the chukchi sea preserve a record of local paleoenvironment sedimentation and flooding of the chukchi shelf 50 m by glacial eustatic sea level rise radiocarbon dates on foraminifera provide the first marine evidence that the sea invaded hope valley southern chukchi sea 53 m as early as 12 ka the lack of significant sediment accumulation since ca 7 ka in hope valley southeastern chukchi shelf is consistent with decreased sediment supply and fluvial discharge to the shelf as deglaciation of alaska concluded abundant benthic foraminifera from a site west of barrow canyon indicate that surface waters were more productive 4 6 ka and this productivity varied on centennial time scales an offshore companion to this core contains a 20 m record of the holocene these results show that carefully selected core sites from the western arctic ocean can have a temporal resolution equal to the best cores from other regions and that these sites can be exploited for high resolution studies of the paleoenvironment

chlorine 36 and 14c chronology support a limited last glacial maximum across central chukotka northeastern siberia and no beringian ice sheet abstract the pekulney mountains and adjacent tanyurer river valley are key regions for examining the nature of glaciation across much of northeast russia twelve new cosmogenic isotope ages and 14 new radiocarbon ages in concert with morphometric analyses and terrace stratigraphy constrain the timing of glaciation in this region of central chukotka the sartan glaciation last glacial maximum was limited in extent in the pekulney mountains and dates to 20 000 yr ago cosmogenic isotope ages 30 000 yr as well as non finite radiocarbon ages imply an estimated age no younger than the zyryan glaciation early wisconsinan for large sets of moraines found in the central tanyurer valley slope angles on these loess mantled ridges are less than a few degrees and crest widths are an order of magnitude greater than those found on the younger sartan moraines the most extensive moraines in the lower tanyurer valley are most subdued implying an even older probable middle pleistocene age this research provides direct field evidence against grosswald s beringian ice sheet hypothesis

volcanic risk ranking for auckland new zealand ii hazard consequences and risk calculation in a companion paper a methodology for ranking volcanic hazards and events in terms of risk was presented and the likelihood and extent of potential hazards in the auckland region new zealand investigated in this paper the effects of each hazard are considered and the risk ranking completed values for effect are proportions of total loss and as with likelihood and extent are based on order of magnitude