localization of a coal seam fire using combined self potential and resistivity data abstract the remediation of coal seam fires requires as a first step the precise localization of the burning front various geophysical methods can be employed for this purpose but not all of them can provide an unambiguous localization of this type of target we propose a combined inversion of self potential and resistivity data and the use of joint attributes characterizing the target to localize the burning front of a coal seam fire this new methodology is applied to the 3d reconstruction of a shallow coal seam fire in boulder colorado the coal seam fire is located in the gorham subbituminous coal formation at a depth comprised between 10 and 15 m the self potential survey comprises 160 stations 5 profiles and 32 stations per profile located at the ground surface with self potential anomalies amounting 70 to 50 mv with respect to an arbitrary reference located further away from the burning front the resistivity survey comprises 5 resistivity profiles with 118 measurements per profile 590 measurements in total the burning front is associated with very low value of the electrical resistivity

coupled ice ocean dynamics in the marginal ice zones upwelling downwelling and eddy generation this study is aimed at modeling mesoscale processes such as upwelling downwelling and ice edge eddies in the marginal ice zones a two dimensional coupled ice ocean model is used for the study the ice model is coupled to the reduced gravity ocean model through interfacial stresses the parameters of the ocean model were chosen so that the dynamics would be nonlinear the model was tested by studying the dynamics of upwelling winds parallel to the ice edge with the ice on the right produce upwelling because the air ice momentum flux is much greater than air ocean momentum flux thus the ekman transport is greater under the ice than in the open water the stability of the upwelling and downwelling jets is discussed the downwelling jet is found to be far more unstable than the upwelling jet because the upwelling jet is stabilized by the divergence a constant wind field exerted on a varying ice cover will generate vorticity leading to enhanced upwelling downwelling regions i e wind forced vortices steepening and strengthening of vortices are provided by the nonlinear terms when forcing is time varying the advection terms will also redistribute the vorticity the wind reversals will separate the vortices from the ice edge so that the upwelling enhancements are pushed to the open ocean and the downwelling enhancements are pushed underneath the ice

detection of water leakage from dams by self potential method abstract a self potential survey of streaming potentials along the eastern embankment of a dam was very successful in locating leakage areas and determining the relative intensity of discharge self potential measurements have shown negative anomalies of up to 100 mv in amplitude the width of the discharge areas ranged between about 40 m and 150 m repeated observations of sp data at two different reservoir levels showed no great change in the leakage flow behaviour detailed mapping of sp values in the area revealed the possible presence of two sinkholes the first with an estimated diameter of about 25 30 m and the second with a diameter of about 15 m based on a qualitative interpretation of the sp anomalies the location of these two sinkholes coincides well with the position of two subsurface normal faults in the area

the last 40 ka tephrostratigraphic record of lake ohrid albania and macedonia a very distal archive for ash dispersal from italian volcanoes abstract a 1075 cm long core lz1120 was recovered in the south eastern part of the lake ohrid republics of macedonia and albania and sampled for identification of tephra layers magnetic susceptibility investigations show rather high magnetic values throughout the core with peaks unrelated to the occurrence of tephra layers but instead to the relative abundance of detrital magnetic minerals in the sediment naked eye inspection of the core allowed us to identify of two tephra layers at 896 897 cm and 1070 1075 cm laboratory inspection of the grain size fraction 125 m allowed for the identification of a third cryptotephra at 310 315 cm major element analyses on glass shards of the tephra layers at 896 897 cm and 1070 1075 cm show a trachytic composition and indicate a correlation with the regionally dispersed y 3 and y 5 tephra layers dated at ca 30 and 39 cal ka bp the cryptotephra at 310 315 cm has a mugearitic benmoreitic composition and was correlated with the fl eruption of mt etna dated at 3370 70 cal yr bp these ages are in agreement with five 14 c ams measurements carried out on plant remains and macrofossils from the lake sediments at different depths along the core the recognition of distal tephra from italian volcanoes allows us to link the lake ohrid succession to other archives located in the mediterranean area and in eastern europe the benmoreitic mugearitic tephra layer at 310 315 cm is the first recognition in the balkan area of a distal ash deposit from a mid intensity explosive eruption of mt etna as far as 600 km from the source

the natal pulse an extreme transient on the agulhas current an analysis of satellite data collected over a period of 9 years as well as historic hydrographic data show that the northern agulhas current is subject to large intermittent and solitary meanders these transient events collectively named the natal pulse progress downstream at consistent rates of 21 cm s upon reaching the area where the shelf broadens their rate of progression slackens to 5 cm s they are present in some stages of development at least 17 of the time extend offshore by about 170 km on average and show a continuous lateral growth on moving downstream with few exceptions the pulses are spawned as cold core cyclonic trapped lee eddies in the natal bight they are held responsible for the intermittent coastal counter currents observed inshore of the agulhas current along the southern african coast and may play a crucial role in sediment distribution on the shelf

mineralogical analyses and in vitro screening tests for the rapid evaluation of the health hazard of volcanic ash at rabaul volcano papua new guinea the continuous ash and gas emissions from the tavurvur cone in rabaul caldera papua new guinea during 2007 08 raised concerns regarding how exposure would affect the respiratory health of nearby populations and impact on the environment as part of a formal evaluation of the effects of volcanic emissions on public health we investigated the potential health hazard of the ash using a suite of selected mineralogical analyses and in vitro toxicity screening tests the trachy andesitic ash comprised 2 1 6 7 vol respirable sub 4 m diameter particles the crystalline silica content was 1 9 5 0 wt cristobalite in the bulk sample with trace amounts of quartz and or tridymite scanning electron microscopy showed that the ash particles were angular with sparse fibre like particles 3 60 m max diameter observed in some samples which we confirmed to be caso4 gypsum at 6 wt in the bulk samples and not asbestiform fibres the ash specific surface area was low 0 1 2 7 m2 g 1 the leached solution from one of the ash samples was slightly acidic ph 5 6 but did not contain high levels of toxic metals such as f cu zn mn as ni and cd when compared to previously tested volcanic ash leachates ash samples generated potentially harmful hydroxyl radicals through an iron mediated catalytic reaction in the range of 0 15 2 47 mol m 2 after 30 min of reaction however measurement of particle oxidative capacity potential oxidative stress reaction using ascorbic acid and silica like injury to red blood cells erythrolysis assay i e measurement of cell death nevertheless revealed low biological reactivity the findings suggest that acute exposure to the ash would have a limited potential to exacerbate pre existing conditions such as asthma or chronic bronchitis and the potential for chronic exposure leading to silicosis was low

self potential monitoring of a salt plume nonintrusively monitoring the spread of contaminants in real time with a geophysical method is an important task in hydrogeophysics we have developed a sandbox experiment showing that the self potential method can locate both the source of leakage and the front of a contaminant plume we monitored the leakage of a plume of salty water from a hole at the bottom of a small tank located at the top of a main sandbox initially the sand was saturated by tap water at a given time a hole was opened at the bottom of the tank allowing the salty water to migrate by diffusion and buoyancy driven flow in the main sandbox the bottom of the sandbox contained a network of 32 nonpolarizing silver silver chloride electrodes with amplifiers connected to a multichannel voltmeter the self potential response associated withthe migration of the salt plume in the sandbox was recorded over time a self potential anomaly was observed with amplitude varying from a few millivolts at the start of the leak to a few tens of mi

the east greenland polar front in autumn closely spaced salinity and temperature measurements in the region of the east greenland polar front from 75 n to 79 n in october november 1981 are presented the return atlantic current rac having a core of relatively warm and saline atlantic intermediate water aiw t 0 5 to 3 0 c s 34 9 to 35 0 was found everywhere along a steep front separating it from the colder fresher polar water a narrow frontal jet was found to have velocities greater than 0 80 m s where the station density was great enough to resolve its concentrated character notable fine structure was present especially in the warm aiw just east of the front a cold saline water forming a knee in the temperature salinity correlation was present in the upper margins of the rac the knee is formed primarily by warm aiw or atlantic water flowing under the upper layers of water flowing from the arctic ocean calculations are presented to show that an initially isothermal underflow could be modified to a thick thermocline by double diffusion calculations of the rate of cooling of fine structure elements by double diffusion indicate that the fine structure would have a limited lifetime about 12 days if its waters were not continually replenished

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

waveform joint inversion of seismograms and electrograms for moment tensor characterization of fracking events electromagnetic signals have been observed in association with fracking experiments in the laboratory and in the field we have developed a seismoelectric forward modeling approach to produce synthetic seismograms and electrograms generated by fracking events using the finite element method with perfect matched layer boundary conditions the poroelastodynamic equations are solved in the frequency domain using a formulation based on the solid phase displacement and the pore pressure these results are used to compute the electrical field disturbances of electrokinetic nature three types of electrical signals are generated type i disturbance is associated with the seismic source itself type ii disturbance corresponds to seismoelectric conversions and type iii corresponds to coseismic signals this model is applied to simulate the seismic and electrical signals corresponding to the occurrence of a fracking event in a two layers system we perform a stochastic joint inversion of the seismograms and electrograms using the adaptive metropolis algorithm ama to obtain the posterior probability density functions of the parameters characterizing the seismic source assuming that the velocity model is perfectly known the joint waveform inversion is performed on synthetic noise free data and the ama algorithm is successful in retrieving the true values of the unknown parameters the proposed approach is then tested on the same synthetic data after being contaminated with 15 random noise with respect to the maximum amplitude of the signals the model parameters are better determined for the joint inversion of seismic and electrical data by comparison with the inversion of the seismic time series alone we also propose a deterministic tomographic algorithm that is successful in locating the in situ source current density distribution for types i and ii anomalies from the electrical data alone

volcanic hazard communication using maps an evaluation of their effectiveness hazard maps are considered essential tools in the communication of volcanic risk between scientists the local authorities and the public this study investigates the efficacy of such maps for the volcanic island of montserrat in the west indies using both quantitative and qualitative research techniques normal plan view maps which have been used on the island over the last 10 years of the crisis are evaluated against specially produced three dimensional 3d maps and perspective photographs thirty two demographically representative respondents of mixed backgrounds sex education and location were interviewed and asked to complete a range of tasks and identification on the maps and photographs the overall results show that ordinary people have problems interpreting their environment as a mapped representation we found respondents ability to locate and orientate themselves as well as convey information relating to volcanic hazards was improved when using aerial photographs rather than traditional plan view contour maps there was a slight improvement in the use of the 3d maps especially in terms of topographic recognition however the most striking increase in effectiveness was found with the perspective photographs which enabled people to identify features and their orientation much more readily for montserrat it appears that well labelled aerial and perspective photographs are the most effective geo spatial method of communicating volcanic risks

application of the mise a la masse method to detect the bottom leakage of water reservoirs abstract leakages of reservoirs are responsible for the loss of water resources and the spread of contaminants we develop a methodology to detect leaks located at the bottom side of a reservoir with the minimally invasive mise a la masse method which involves the potential electrodes located at the ground surface around the reservoir and the current source and sink placed in and out of the reservoir respectively this method allows localizing the secondary current distribution associated with leakage using the distribution of potential recorded on a set of electrodes during the mise a la masse experiment an initial model based on the distribution of root mean square values between the observation and the simulation data is first given to the inversion algorithm the tikhonov regularization which includes a weighting matrix and a minimum support function is used to strengthen the detection resolution of the leak 29 sandbox experiments show that the proposed method and inversion algorithm can localize a single leak for a leak with a crack shape the inversion algorithm detects the location of the leak with a small bias when the leak lasts a conductive zone may occur below the leak due to the increase of water content or ionic strength of the pore water the occurrence of such a conductive body could affect the localization of the leak because the conductivity distribution may not be well resolved the effect is analyzed using synthetic experiments the results show that the bias between the real leak and inversion results increases with the position and size of the undetected conductive zone two small scale field tests were conducted to test the performance of the mise a la masse method the two leaks are properly identified this study provides an efficient approach to detect the bottom leakage of reservoirs

mesoscale eddies in the fram strait marginal ice zone during the 1983 and 1984 marginal ice zone experiments during the summer marginal ice zone experiment in fram strait in 1983 and 1984 fourteen mesoscale eddies in both deep and shallow water were studied between 78 o and 81on sampling combined satellite and aircraft remote sensing observations conductivity temperature depth observations drift of surface and subsurface floats and current meter measurements typical scales of these eddies were 20 40 km rotation was mainly cyclonic with a maximum speed in several cases subsurface of up to 40 cm s observations further suggest that the eddy lifetime was at least 20 to 30 days five generation sources are suggested for these eddies several of the eddies were topographically trapped while others primarily formed by combined baroclinic and barotropic instability moved as much as 10 15 km d with the mean current the vorticity balance in the nontrapped eddies is dominated by the stretching of isopycnals accompanied by a change in the radial shear in the most completely observed eddy south of 79on the available potential energy exceeded the kinetic energy by a factor of 2 quantitative estimates suggest that the abundance of these eddies enhances the ice edge melt up to 1 2 km d

proximal tephra hazards recent eruption studies applied to volcanic risk in the auckland volcanic field new zealand abstract auckland new zealand is unique in being a metropolitan area built on an active volcanic field despite the small size and intensity of auckland eruptions the risk from tephra fall is high because of the high density of buildings and lifelines the nature of this threat can be evaluated by comparisons with historical strombolian and hawaiian eruptions which have occurred in non populated areas cone building phases of such eruptions are typically protracted i e weeks to months in duration prolonging the period during which emergency managers will have to fine tune mitigation for numerous parameters such as fluctuations in intensity and wind shifts rapid cone growth during future eruptions will define a region of some 30 to 100 ha where complete destruction will occur on a time scale of hours the cost of this destruction is likely to range between nz 200m and nz 1 4b ca us 130m to us 900m beyond this we have modeled the cumulative long term effect of the build up of a downwind blanket of lapilli and ash by estimating accumulation rates for three phases of the 1959 k lauea iki eruption in hawai i the effect of changing wind direction was evaluated using low level wind data from auckland these results show that intervals between 4 and 100 h will lapse before onset of significant damage to buildings

electrokinetic spontaneous polarization in porous media petrophysics and numerical modelling abstract the behaviour of streaming potential is directly related to movement of groundwater the responses for typical subsurface flows are modelled to investigate possibilities of spontaneous polarization sp when performing quantitative data interpretation the physical properties of geomaterials related to streaming potential are described a magnitude range of streaming current coefficient is assessed for geomaterials and found to be from 10 10 to 10 8 a pa m depending on water salinity and rock composition the electrical sources of sp caused by groundwater flow in saturated media are theoretically described it is shown that sp is completely defined by three types of electrical sources situated 1 on boundaries where water enters or quits porous media 2 in areas with transient regime and 3 on the boundaries of rocks with different properties hydraulic conductivity streaming current coefficients and electrical conductivity a 2d computer program based on the method of finite difference was created to provide numerical successive modelling of both groundwater flow and sp using sill s geophysics 48 1983 76 approach first the water heads are calculated then electrical sources of sp are obtained on the basis of the calculated heads and coefficient of streaming current finally the sp is obtained on the basis of calculated electrical sources and subsurface electrical conductivity numerical examples illustrating sp responses of infiltration of barrage with different electrical conductivity and of well pumping are discussed field data obtained at the site containing the dam between superficial artificial reservoir and the river are interpreted on the basis of numerical modelling the discussed method can be mainly used for additional calibration of groundwater flow models

a general theory for the effect of local topographic unevenness on contourite deposition around marine capes an inverse problem applied to the italian continental margin cape suvero abstract the interaction between ocean bottom currents and topographic obstacles often results in sedimentary processes that form intriguing sedimentary deposits however without a thorough knowledge of both fluid mechanical processes and oceanographic settings regarding these sedimentary deposits such an inherited interaction is not easy to understand we here analyze the interaction between a bottom geostrophic current and a local topographic depression a slide scar offshore cape suvero an italian headland in the southern tyrrhenian sea in order to explain the presence of contourite drifts off this cape we apply the classical conservation of marine water potential vorticity and demonstrate the presence of a steady cyclonic circulation over the scar which in turn affects contourite deposition we thus show that the application of the potential vorticity conservation provides a simple but powerful general tool for the understanding of the complex relations among ocean current seafloor morphologies and sedimentary structures

ice edge eddies in the fram strait marginal ice zone five prominent ice edge eddies in fram strait on the scale of 30 to 40 kilometers were observed over deep water within 77 n to 79 n and 5 w to 3 e the use of remote sensing a satellite tracked buoy and in situ oceanographic measurements showed the presence of eddies with orbital speeds of 30 to 40 centimeters per second and lifetimes of at least 20 days ice ablation measurements made within one of these ice ocean eddies indicated that melting which proceeded at rates of 20 to 40 centimeters per day is an important process in determining the ice edge position these studies give new insight on the formation propagation and dissipation of ice edge eddies

determination of the permeability of seepage flow paths in dams from self potential measurements abstract the flow of the pore water in porous media generates an electrical current known as the streaming current this current is due to the drag of the excess of charges contained in the electrical diffuse layer coating the surface of the grains this current is associated with an electric field called the streaming potential field the fluctuations of this field can be remotely measured using a set of non polarizable electrodes located at the ground surface or in wells and a sensitive voltmeter the self potential method sp aims at passively measuring the streaming potential anomalies associated with ground water flow we present a stochastic numerical framework for inverting self potential data in order to localize seeps in dams and characterize their permeability and darcy velocity our approach is based on the use of markov chains monte carlo mcmc method for solving the inverse problem we performed first a validation of the method on a synthetic case study and then on large scale field surveys on three different dams our approach is successful in localizing seeps and determining their permeability a sensitivity study is performed on each of these three dams to better define the hydraulic and electrical parameters influencing the self potential signal and the uncertainties associated with the estimation of those parameters our results show that the self potential method can provide quantitative hydrogeological information for the characterization of seeps in dams and dikes

the interaction of a two layer isolated mesoscale eddy with bottom topography abstract the propagation of an isolated mesoscale eddy onto a western bounding topographic slope is examined through the use of a two layer primitive equation numerical model variable parameters in the study are sense of rotation cyclonic anticyclonic vertical structure baroclinic barotropic and layer thickness ratio h1 h2 eddy size and strength rotational velocity and frictional parameterization are fixed dispersion in the isolated eddy is induced by planetary and topographic beta effects giving the eddy an asymmetric distribution this asymmetric distribution allows for nonlinear self advective propagation tendencies these nonlinear tendencies play a key role in the direction of propagation of the eddy specifically in a quiescient background an anticyclone can have eastward propagation tendencies which can overcome planetary and topographic beta effects conversely cyclones can have westward propagation velocities which are augmented greater than maximum rossby wave phase speed b

influence of the institutional and socio economic context for responding to disasters case study of the 1994 and 2006 eruptions of the merapi volcano indonesia

the gin sea a synthesis of its physical oceanography and literature review 1972 1985 abstract a synthesis and review of the physical oceanography of the gin sea greenland iceland and norwegian seas is presented an accompanying bibliography is included from 1972 through 1985 some 1986 works are also noted emphasis is placed on describing the gin sea as a major semi enclosed basin that plays a role unique among the world s oceans by providing a strong two way advective exchange between the ice covered polar sea and the north atlantic ocean and at the same time acting as the primary site for northern hemisphere bottom water formation the water masses for the gin sea are defined in a manner as consistent as possible with the literature the large scale oceanographic and meteorological factors influencing the water mass formation and circulation are described a sample calculation of the various horizontal and vertical thermohaline driven exchanges is given

self potential signals associated with localized leaks in embankment dams and dikes abstract the self potential method can be used to detect and monitor anomalous seepages in dams and embankments in such a case an electrical field of electrokinetic nature i e associated with pore water flow can be measured using a set of non polarizable electrodes typically located at the ground surface or in some wells this field can be in turn related to the pattern of groundwater flow we built an experimental dam to investigate to which extent the self potential method can help characterizing seepages in dams we first use the finite element method to simulate the ground water flow in a heterogeneous porous and permeable material by solving the groundwater flow equation the resulting groundwater flow solution is then used to compute the electrical potential distribution by solving the corresponding elliptic partial differential equation in a preliminary experiment we could not measure any self potential anomaly associated with the infiltration of water in the dam our numerical simulations showed that the magnitudes of the self potential anomalies were controlled by 1 the nature of the flow regime viscous laminar versus inertial laminar flow regimes and 2 the presence of insulating polyvinyl chloride pvc tubes located at the end of the preferential flow channels in the structure of the dam thanks to these numerical simulations we added sand at the entrance of the infiltration area in order to reduce the effects of the pvc tubes and to restrain the flow regime to the viscous laminar flow regime new experiments allowed for detecting a self potential anomaly with an amplitude of around 9 mv consistent with that obtained through numerical modelling with a finite element simulator this comparison was used to test the accuracy of the modelling approach and define the strengths and weaknesses of the self potential method to determine preferential seepages in earth dam structures

eddy near the molloy deep revisited a warm 60 km diameter cyclonic eddy was observed in late summer 1984 in the vicinity of the molloy deep at the eastern edge of the east greenland current depression of isotherms to at least 900 m indicates a deep reaching baroclinicity maximum baroclinic speeds of 0 1 to 0 17 m s are estimated as is a swirl transport of 1 sv

branching of atlantic water within the greenland spitsbergen passage an estimate of recirculation atlantic water aw supplies the largest source of heat mass and salt to the arctic ocean via fram strait greenland spitsbergen passage yet it represents only a fraction of the atlantic water that resides in the greenland iceland norwegian and barents seas this is a result of both the branching of the central core of aw along its northward flow and the modification of its t s signature through air sea ice interactions and internal mixing this paper addresses the quantitative analysis of the three dominant atlantic water cores within fram strait and north of 76 n using an 11 year 1977 to 1987 hydrographic database spatial variations of heat volume and salt along its flow path of some 600 km showed that the major core of atlantic water that directly enters the arctic ocean svalbard branch did not extend past 20 e of the 9719 km3 of atlantic water existing within the region one third resided within the svalbard branch the remainder 22 and 45 were held within the return atlantic current and the yermak branches respectively restricting the analysis to a southern limit of 79 n effectively removed the return atlantic current and showed a nearly equal split between the two remaining branches work completed by bourke et al 1988 indicated that the yermak branch is largely recirculated to the south if true this analysis supports rudels 1987 model estimate of a 50 recirculation of aw within this region

perceptions of hazard and risk on santorini abstract santorini greece is a major explosive volcano the santorini volcanic complex is composed of two active volcanoes nea kameni and mt columbo holocene eruptions have generated a variety of processes and deposits and eruption mechanisms pose significant hazards of various types it has been recognized that for major european volcanoes few studies have focused on the social aspects of volcanic activity and little work has been conducted on public perceptions of hazard risk and vulnerability such assessments are an important element of establishing public education programmes and developing volcano disaster management plans we investigate perceptions of volcanic hazards on santorini we find that most residents know that nea kameni is active but only 60 know that mt columbo is active forty percent of residents fear that negative impacts on tourism will have the greatest effect on their community in the event of an eruption 43 of residents would try to evacuate the island by plane ferry residents aged 50 have retained a memory of the effects of the last eruption at the island whereas younger residents have no such knowledge we find that dignitaries and municipal officers those responsible for planning and managing disaster response are informed about the history hazards and effects of the volcanoes however there is no emergency plan for the island and there is confusion between various departments civil defense fire police etc about the emergency decision making process the resident population of santorini is at high risk from the hazards associated with a future eruption

identification of leakage and potential areas for internal erosion combining ert and ip techniques at the negratin dam left abutment granada southern spain abstract at the negratin dam southern spain two main springs derived from the water reservoir were detected on the west side of the mountain ridge matching the location of the left abutment of the dam the seepages appear when the level of the stored water exceeds 622 m above sea level m a s l where some paleochannels are embedded in the silts the water level was at 631 m a s l on the day of the measurements 13 12 23 close to the historical maximum 633 78 m a s l although the water crossing the leaks does not drag particles nowadays this sector may potentially cause internal erosion or piping phenomena implying a loss of water resources and slope instability problems the infiltration areas were evaluated by electrical resistivity and induced polarization methods measured along one profile on the mountain ridge between the water reservoir and the springs we determine that the infiltrations zones are characterized by low resistivity and high chargeability distributed in small areas we demonstrate that these methods are a reliable tool to detect and characterize infiltration zones and they are the first step to planning mitigation actions to avoid the piping phenomena

three dimensional modelling of streaming potential summary the self potential sp method responds to the electrokinetic phenomenon of streaming potential and has been applied to hydrogeologic and engineering investigations to aid in the evaluation of subsurface hydraulic conditions to enable the study of variably saturated flow problems of complicated geometry a 3 d finite volume algorithm is developed to evaluate the sp distribution resulting from subsurface fluid flow the algorithm explicitly calculates the distribution of streaming current sources and solves for the sp given a model of hydraulic head and prescribed distributions of the streaming current cross coupling conductivity and electrical conductivity the forward solution is verified by comparing it with an analytical solution for a point source of flow and measured data taken at the surface of a homogeneous embankment we apply the forward model to a synthetic pumping well example to illustrate that heterogeneous physical property distributions can result in significant charge accumulation the sign and magnitude of this secondary charge is determined by the physical property and potential gradients at the interface and can complicate the interpretation of sp data when a single primary flow source is assumed the 3 d character of the sp response to seepage through an embankment and foundation is illustrated in a preliminary study of sp data collected at a dam site in british columbia

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

potential impacts from tephra fall to electric power systems a review and mitigation strategies modern society is highly dependent on a reliable electricity supply during explosive volcanic eruptions tephra contamination of power networks systems can com promise the reliability of supply outages can have signifi cant cascading impacts for other critical infrastructure sectors and for society as a whole this paper summarises known impacts to power systems following tephra falls since 1980 the main impacts are 1 supply outages from insulator flashover caused by tephra contamination 2 dis ruption of generation facilities 3 controlled outages during tephra cleaning 4 abrasion and corrosion of exposed equipment and 5 line conductor breakage due to tephra loading of these impacts insulator flashover is the most common disruption the review highlights multiple instan ces of electric power systems exhibiting tolerance to tephra falls suggesting that failure thresholds exist and should be identified to avoid future unplanned interruptions to ad dress this need we have produced a fragility function that quantifies the likelihood of insulator flashover at different thicknesses of tephra finally based on our review of case studies potential mitigation strategies are summarised specifically avoiding tephra induced insulator flashover by cleaning key facilities such as generation sites and trans mission and distribution substations is of critical importance in maintaining the integrity of an electric power system

self potential modeling from primary flows this paper discusses a new method for the investigation of self potentials sp based on induced current sources the induced current sources are due to divergences of the convection current which is driven in turn by a primary flow either heat or fluid as a result of using this approach there is a shift in emphasis toward the vector flow field and its interaction with current cross coupling structure when compared with the total potential approach of nourbehecht 1963 which emphasized the primary flow potential and the voltage cross coupling this shift in emphasis is advantageous because it is analogous to the actual physical processes for example fluid flow in the ground gives rise to drag convection currents and the interaction of the convection currents with the electrical structure gives rise to the electrical potentials sp this simple physical picture should aid in developing a better intuitive understanding of the generation of sp effects the convective current approach is easily ada

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

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

assessing preferential seepage and monitoring mortar injection through an earthen dam settled over a gypsiferous substrate using combined geophysical methods abstract for several decades the sant llorenc de montgai reservoir has experienced different problems that could affect the safety of the engineering structure for this reason several corrective actions have been taken over the years here we present a study involving complementary geophysical methods including electrical resistivity tomography seismic refraction tomography and frequency domain electromagnetic surveys the analysis of the inverted electrical resistivity tomography cross sections combined with the seismic refraction results and land subsidence monitoring data show the likely mechanism of abnormal seepage the areas where mortar injections were applied as a corrective measure are also clearly delineated in addition the evolution of the state of the embankment has been established from two successive electrical resistivity tomography surveys in the last two decades the results show areas where corrective mortar injections have been effective while in other areas new abnormal seepage has been detected the lithological heterogeneity of the bedrock especially the dissolution of gypsum rich rocks induced subsidence effects and caused abnormal seepage in different areas along the embankment our results indicate how corrective solutions can be optimized to reduce the cost of corrective engineering interventions

electric potential source localization reveals a borehole leak during hydraulic fracturing abstracta laboratory experiment was performed to see if passively recorded electric signals can be inverted to retrieve the position of fluid leakages along a well during an attempt to hydraulically fracture a porous block in the laboratory the cubic block was instrumented with 32 nonpolarizing sintered ag agcl electrodes during the test several events were detected corresponding to fluid leakoff along the seal of the well each event showed a quick burst in the electric field followed by an exponential type relaxation of the potential distribution over time the occurrence of these electric events was always correlated with a burst in the acoustic emissions and a change in the fluid pressure these self potential data were inverted in two steps 1 using a deterministic least square algorithm with focusing to retrieve the position of the source current density in the block for a given snapshot in the electric potential distribution and 2 using a genetic algorithm to refine the position of the sou

topographic generation of an eddy at the edge of the east greenland current wadhams and squire 1983 describe an ice water eddy at the edge of the east greenland current located at about 79 and 1 e the eddy has been sighted earlier vinje 1977 and appears to occur in that general location with some regularity wadhams and squire explain the eddy in terms of baroclinic instability the criteria of griffiths and linden 1982 and phillips 1954 suggest that the east greenland current is baroclinically unstable and phillips theory indicates that the most unstable wavelength of a sinusoidal velocity perturbation is 50 km in agreement with the approximate size of the observed eddy

feedback between ice flow barotropic flow and baroclinic flow in the presence of bottom topography coupling between externally driven barotropic flow and locally driven baroclinic flow in the presence of an ice cover and topography is studied the topography is a necessary ingredient in this coupling this study shows that the observed mesoscale activity of the ice edge seen in satellite imagery does not necessarily reflect the mesoscale baroclinic activity in the ocean besides oceanic eddies the ice cover can trace the topographic changes via the coupling to the barotropic flow a two layer ocean model coupled to an ice model is constructed to simulate an ice ocean system with a varying bottom topography in the absence of wind forcing the ice cover reflects the externally driven barotropic ocean response especially topographically forced taylor columns by forming ice streamers or meanders some of these features propagate advected with the ocean currents as a whole downstream creating an image of eddy propagation even though there is no baroclinic structure underneath when downwelling favorable winds ice on the left from the wind direction are turned on in addition to this background barotropic flow the ekman flow in the ocean toward the open ocean will enhance the meandering of the ice edge due to the barotropic flow during upwelling favorable winds the ice edge stays rather compact including the case when a strong baroclinic cyclonic vortex is developing beneath an ice meander supported by the taylor column in the ocean

thermoelectric self potential and resistivity data localize the burning front of underground coal fires abstractself potential signals and resistivity data can be jointly inverted or analyzed to track the position of the burning front of an underground coal seam fire we first investigate the magnitude of the thermoelectric coupling associated with the presence of a thermal anomaly thermoelectric current associated with a thermal gradient a sandbox experiment is developed and modeled to show that in presence of a heat source a negative self potential anomaly is expected at the ground surface the expected sensitivity coefficient is typically on the order of 0 5 mv c 1 in a silica sand saturated by demineralized water geophysical field measurements gathered at marshall near boulder co show clearly the position of the burning front in the electrical resistivity tomogram and in the self potential data gathered at the ground surface with a negative self potential anomaly of about 50 mv to localize more accurately the position of the burning front we developed a strategy based on two steps 1 we

current regimes across the east greenland polar front at 78 40 north latitude during summer 1984 four weeks of concurrent temperature and current observations from three moorings across the east greenland polar front at approximately 78 40 n showed pronounced differences between the current regimes on either side of the front east of the front vertical shear was minimal mean flow was not statistically significant and fluctuations showed evidence of wind influence west of the front vertical shear and southward mean flow were significant however observed fluctuations were not strongly influenced by local winds the mean current and density structure of the front was similar to that of a two layer boundary current model with constant potential vorticity current fluctuations west of the front were in part related to mesoscale features generated farther north and subsequently advected downstream by the east greenland current or to eddylike features apparently generated through potential vorticity conservation local instabilities of the front most likely account for the remainder of the mesoscale variability seen in the records

an ice water vortex at the edge of the east greenland current during the y mer 80 cruise in august 1980 we observed an ice feature of 60 km diameter having the shape of a breaking wave it lay at the edge of the east greenland drift ice in fram strait with its center at 79 15 n 00 38 e and the wave was breaking upstream relative to the east greenland current two conductivity temperature and depth sections across the feature in n s and e w directions revealed warm up to 4 3 c water some 60 km inside the polar front in lenses centered at 40 m depth but with an effect to beyond 600 m the temperature anomalies were accompanied by salinity anomalies so that there was little net effect on the density profile the form of the sections together with the ice distribution observed by vertical photography from a helicopter and surface motion observed by tracking four radar transponders all suggest that the feature is a vortex produced by an instability in the polar front it has similar characteristics to vortices investigated experimentally and theoretically by griffiths and linden 1981a b 1982 and observationally by wadhams et al 1979

sea ice thickness distribution in the greenland sea and eurasian basin may 1987 upward sonar data from a 3400 km track in the greenland sea and the eurasian basin of the arctic ocean obtained by a british submarine in may 1987 have been statistically analyzed mean ice thicknesses in the greenland sea show significant melting with downstream distance at an average rate of 0 38 m per degree of latitude equivalent to about 2140 km3 yr 1 of freshwater input between 80 n and 75 n in the region north of fram strait between 82 n and 80 n there is remarkable consistency between mean ice drafts in 1987 and in three previous cruises 1976 1979 1985 while between greenland and the north pole there was a significant thinning in 1987 relative to 1976 in fram strait the mean ice draft shows evidence of thinning within the region of influence of a semipermanent eddy ice draft distributions show that the probability density function of deformed ice follows a negative exponential distribution and that the change of shape of the distribution with downstream distance in the greenland sea is due to preferential melting of thicker ice pressure ridge draft distributions also fit a negative exponential while their spacings fit a lognormal distribution lead width distribution follows a power law with an exponent of 1 45 for narrow leads and 2 50 for wider leads if leads are defined as having a 1 m maximum draft 1 67 and 2 76 for a 0 5 m maximum draft lead spacings follow a negative exponential distribution for moderate spacings 400 1500 m but with an excess of lead pairs at small and very large spacings

effects of sub ice mesoscale features within the marginal ice zone of fram strait four distinct sub ice mesoscale features were observed during the 1983 marginal ice zone experiment in fram strait the first one was an anticyclonic eddy located over the yermak plateau and strongly correlated with bottom topography however it appears not to have been topographically generated the remaining features were observed along the ice edge of the east greenland current two were closely related in that one was a filament of atlantic water that was apparently entrained by a warm core cyclonic eddy located northwest of the molloy deep the last one could not be shown conclusively as a westward extension of a branch of atlantic water or an isolated cyclonic eddy simplified estimates show that on average each of the three features had enough available heat energy residing within the first 30 m of their cores to melt over 600 km2 of 2 m thick ice other estimates of potential melting and retreat rates of the marginal ice zone are calculated on the basis of various utilization depths from which available heat energy can be drawn further consideration is also given to the possibility that these types of features may also act as destructive preconditioners of sea ice since it is unlikely that complete melting would occur because of their relative movements eddies and intrusions significantly increase the amount of available temperature salinity t s space within which mixing can be accomplished these admixtures produced by direct interaction of atlantic water or atlantic intermediate water and the polar waters of the east greenland current further provide a very effective mechanism which transports salt to deeper levels through salt fingering and double diffusion calculations of heat mass and salt fluxes for the observed features show that the heat transported by the ice edge eddies was significant in comparison with a depth comparable flux of the east greenland current while mass and salt fluxes were roughly 7 times less

2d self potential tomographies for studying groundwater flows in the varco d izzo landslide basilicata southern italy abstract a geoelectrical monitoring activity has been carried out to improve the geological and hydrogeological knowledge about the varco d izzo landslide potenza basilicata southern apennine italy an active rotational translational slide evolved in earth flow in this work we have focused on the self potential sp method by applying three different sp measuring techniques and combining modern technologies for data acquisition and new methods for tomographic inversion a sp map and three static sp tomographies have been carried out to better analyse the groundwater circulation system and to better reconstruct the geometry of the landslide body in the accumulation zone which is the area more exposed to the geomorphological activity a new sp measuring strategy has been applied this strategy based on time continuous 2d sp tomographies helps identify water flow changes in subsurface by studying the time series of sp tomographic images the analysis of time dependent changes of water infiltration in near surface is the key to better understand the hydrogeological processes underlying the ground instability phenomena the time lapse analysis of tomographic images has allowed us not only to investigate the correlation between the temporal changes of sp signals and rainfall events but also to quantify the range of these changes the modification of the distribution of the sp source accumulation zones is associated with the dynamics of the groundwater flows these preliminary results allow us to consider the sp tomographic method as a tool for geophysical monitoring of landslide areas and encourage to develop new measuring systems for near real time applications

large scale oceanography in fram strait during the 1984 marginal ice zone experiment the pattern of large scale circulation in fram strait during summer 1984 is inferred from hydrographic data and water mass analysis and direct current observations by use of surface and subsurface floats the west spitsbergen current carrying warm and salty atlantic water splits into several branches two flowing northward into the arctic ocean and two turning westward causing a recirculation across the main axis of fram strait the individual flow paths are topographically controlled suggesting a strong barotropic component of the circulation

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

a numerical study of mesoscale ocean eddy interaction with a marginal ice zone observations made during the marginal ice zone experiment mizex program indicated the presence of mesoscale eddies in a marginal ice edge ocean front in the east greenland current the eddies range in scale from 5 to 80 km physical mechanisms including barotropic and baroclinic instability may be responsible for their presence although the evolution of isolated eddies at low latitudes has been the focus of many studies the effect of ice cover on eddy evolution and vice versa has had less attention here an examination of the interaction of isolated mesoscale ocean eddies with a marginal ice zone is presented results are obtained with a two layer nonlinear primitive equation ocean model and a coupled free drift ice model in the absence of winds the ice equilibrates rapidly to the ocean eddy velocity resulting in radial ice motion the ocean sea surface slope is found to provide an important force in the ice momentum balance in no wind simulations with along ice edge 10 m s winds the ice responds largely to the wind and to a lesser extent to the ocean eddy under ice the ocean eddy can be rapidly eroded by wind driven ice motion cyclones anticyclones are rapidly destroyed by along ice edge winds with ice on the left right

3d geostatistical inversion of induced polarization data and its application to coal seam fires we applied the principal component geostatistical approach pcga to the inversion of time domain induced polarization data in terms of resistivity and chargeability distributions the pcga presents two major advantages over standard methods 1 it avoids the storage of the usually large covariance matrix which contains the geostatistical information by factorizing it in a product of low rank matrices 2 it does not assemble the jaco bian matrix per se we determine the robustness of this approach with three examples we first reconstruct the electrical conductivity and chargeability fields of two synthetic models generated using the geostatistical software stanford geostatistical modeling software the pcga approach performs better than the tikho nov based regularization approach when the true fields are very heterogeneous and the amount of data is limited the third example is devoted to a field study over the former lewis coal mine in colorado usa we perform a 3d localization of the burning front of this coal seam fire by applying our geostatistical inverse methodology to a time domain induced polarization data set in this case the horizontal components of the semivariogram are determined from a self potential map and the correlation length scale for the vertical component is determined from the known thickness of the coal bed the tomogram presents a high normalized chargeability associated with the burning front we evaluate the high normalized chargeability of the burning front in terms of the physical mechanism associated with the cation exchange capacity of the coal and the effect of temperature this demonstrates the potential of the geostatistical inversion and its suitabil ity for inverting geophysical data especially when the data density is sparse in the case of coal seam fires we determine the suitability of the induced polarization method to localize the burning front and the effect of temperature on the normalized chargeability

warm water pathways toward nioghalvfjerdsfjorden glacier northeast greenland nioghalvfjerdsfjorden glacier 79ng is the largest of three marine terminating outlet glaciers draining the northeast greenland ice stream to understand how atlantic waters supply waters in the cavity beneath the floating 79ng we analyze historic and recent bathymetric hydrographic and velocity observations obtained on the northeast greenland continental shelf the bathymetry is characterized by a trough system consisting of the westwind trough and the norske trough in the northern and southern part of the continental shelf respectively atlantic waters recirculating in fram strait cross the shelf break and enter the trough system at its southeastern inlet toward the inner shelf warm atlantic intermediate water aiw present below 200 m in the norske trough shows large contributions of the recirculating atlantic water we found that the bathymetry is sufficiently deep to provide a direct subsurface pathway for warm aiw between the shelf break and the 79ng cavity via the norske trough likewise based on the hydrographic data we show that the norske trough supplies aiw warmer than 1 c to the 79ng which is not present in the westwind trough our moored and lowered velocity measurements indicate that a boundary current carries warm aiw along the northeastern slope of norske trough toward the 79ng we suggest that anomalies in atlantic water temperatures in fram strait could reach 79ng within less than 1 5 years thereby modifying the glacier s basal melt rates

the perception of volcanic risk in kona communities from mauna loa and hualālai volcanoes hawai i abstract volcanic hazards in kona i e the western side of the island of hawai i stem primarily from mauna loa and hual lai volcanoes the former has erupted 39 times since 1832 lava flows were emplaced in kona during seven of these eruptions and last impacted kona in 1950 hual lai last erupted in ca 1800 society s proximity to potential eruptive sources and the potential for relatively fast moving lava flows coupled with relatively long time intervals since the last eruptions in kona are the underlying stimuli for this study of risk perception target populations were high school students and adults n 462 using these data we discuss threat knowledge as an influence on risk perception and perception as a driving mechanism for preparedness threat knowledge and perception of risk were found to be low to moderate on average fewer than two thirds of the residents were aware of the most recent eruptions that impacted kona and a minority felt that mauna loa and hual lai could ever erupt again furthermore only about one third were aware that lava flows could reach the coast in kona in less than 3 h lava flows and ash fall were perceived to be among the least likely hazards to affect the respondent s community within the next 10 years whereas vog volcanic smog was ranked the most likely less than 18 identified volcanic hazards as amongst the most likely hazards to affect them at home school or work not surprisingly individual preparedness measures were found on average to be limited to simple tasks of value in frequently occurring domestic emergencies whereas measures specific to infrequent hazard events such as volcanic eruptions were seldom adopted furthermore our data show that respondents exhibit an unrealistic optimism bias and infer that responsibility for community preparedness for future eruptions primarily rests with officials we infer that these respondents may be less likely to attend to hazard information react to warnings as directed and undertake preparedness measures than other populations who perceive responsibility to lie with themselves there are significant differences in hazard awareness and risk perception between students and adults between subpopulations representing local areas and between varying ethnicities we conclude that long time intervals since damaging lava flows have occurred in kona have contributed to lower levels of awareness and risk perceptions of the threat from lava flows and that the on going eruption at k lauea has facilitated greater awareness and perception of risk of vog but not of other volcanic hazards low levels of preparedness may be explained by low perceptions of threat and risk and perhaps by the lack of a clear motivation or incentive to seek new modes of adjustment

timber framed building damage from tephra fall and lahar 2015 calbuco eruption chile abstract assessing the damage to buildings from volcanic eruptions is an important aspect of volcanic risk assessment and management however there is a limited empirical evidence base to draw upon when describing the relation between volcanic hazard intensity and resulting physical damage the 2015 subplinian eruption of calbuco volcano chile caused damage to buildings near the volcano because of tephra fall and lahars chilean authorities conducted a damage assessment of 961 properties 990 buildings to inform an assistance programme for property owners affected by the eruption property assessments typically contained observations and classification of damage to a house and in some instances accessory buildings such as sheds garages and exterior storage rooms in this study we used this unique damage data set to adapt damage state frameworks for tephra fall and lahar for classifying and analysing damage observations we developed data quality indicators to provide transparency for how we accounted for data quality issues we assigned a tephra and or lahar damage state to 571 buildings 530 houses and 41 accessory buildings the 419 buildings for which we did not assign a damage state either had too little information or fell outside of tephra and or lahar hazard zones the minimum tephra thickness isopach band that caused complete collapse was 10 to 15 cm dry deposit loading 1 to 1 6 kn m 2 saturated deposit loading 1 6 to 2 4 kn m 2 but most commonly 55 of tephra exposed ds5 houses n 11 this occurred at 15 to 30 cm dry deposit loading 1 5 to 3 3 kn m 2 saturated deposit loading 2 4 to 4 8 kn m 2 lahar damage was typically described as complete ds5 with 26 houses being swept away or destroyed around the blanco south river our results add to the limited evidence base of post eruption tephra and lahar impacts to buildings and contribute to volcanic risk and impact assessment

detection of seepage paths in earth dams using self potential and electrical resistivity methods abstract earth and rockfill dams are designed to operate under steady state seepage anomalous seepage may be a threat to the integrity of the structure in spite of advances made in the fields of geotechnical engineering it is not possible to have 100 leak proof structure any excessive and unplanned seepage may lead to the failure of the dam especially in unconsolidated or fractured terrains geophysical methods play an important role in mapping seepage paths and monitoring the changes of the seepage with time enabling to plan technically and economically worthwhile remedial measures in the present paper utilisation of electrical methods for delineation of seepage zones at two of the four saddle dams of the som kamla amba project rajasthan state india which is founded on heterogeneous rock mass is discussed electrical resistivity method was used to delineate zones favourable for seepage whereas self potential sp method was used to delineate the seepage paths sp measurements have shown negative anomaly of the order of 10 20 mv in amplitude indicating low seepage coinciding with the seepage measurements made by the project authorities

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

volcanic hazard impacts to critical infrastructure a review abstract effective natural hazard risk assessment requires the characterisation of both hazards and vulnerabilities of exposed elements volcanic hazard assessment is at an advanced state and is a considerable focus of volcanic scientific inquiry whereas comprehensive vulnerability assessment is lacking cataloguing and analysing volcanic impacts provide insight on likely societal and physical vulnerabilities during future eruptions this paper reviews documented disruption and physical damage of critical infrastructure elements resulting from four volcanic hazards tephra fall pyroclastic density currents lava flows and lahars of eruptions in the last 100 years we define critical infrastructure as including energy sector infrastructure water supply and wastewater networks transportation routes communications and critical components common trends of impacts and vulnerabilities are summarised which can be used to assess and reduce volcanic risk for future eruptions in general tephra falls cause disruption to these infrastructure sectors reducing their functionality whilst flow hazards pyroclastic density currents lava flows and lahars are more destructive causing considerable permanent damage volcanic risk assessment should include quantification of vulnerabilities and we challenge the volcanology community to address this through the implementation of a standardised vulnerability assessment methodology and the development and use of fragility functions as has been successfully implemented in other natural hazard fields

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

building damage in rabaul papua new guinea 1994 damage information on 173 buildings was collected in the immediate aftermath of the september 1994 eruption which destroyed large sections of rabaul town papua new guinea the extent of damage is presented on a five point scale and related to construction characteristics and tephra load total roof loads in rabaul town ranged from 2 to 16 kn m 2 about 100 to 950 mm tephra thickness most buildings which collapsed completely experienced loads 7 5 kn m 2 but many buildings sustained half this load with little more than cosmetic damage timber framed buildings suffered more than buildings with at least some concrete block walls however some old steel framed buildings experienced severe damage with tephra loads as low as 2 kn m 2 comparisons with tephra loads and building damage elsewhere are limited but suggest that rabaul buildings experiencing roof loads of 2 5 kn m 2 generally survived reasonably well however the comparisons are unsatisfactory because of inadequate data on tephra unit weights roof design building ages the quality of workmanship and the natural variability of construction materials particularly timber the rabaul data suggest that concrete block walls increase building resistance to tephra loads but it is doubtful that conventional residential buildings can be designed to sustain tephra loads exceeding 7 kn m 2 the rabaul experience also indicates that building codes for volcanic areas need to consider mudfills and post eruption corrosion of sheet metal roofs and wall cladding most importantly had the majority of buildings in rabaul survived the september 1994 tephra falls wet season mudflows a few months later would still have made most of the town unsafe and uninhabitable