topographic controls on the surface energy balance of a high arctic valley glacier 1 this paper presents the results of a distributed two dimensional surface energy balance model used to investigate the spatial and temporal variations in the surface energy balance of midre lovenbreen a small valley glacier in northwest spitsbergen svalbard over the summer of 2000 we utilize high resolution airborne lidar data to derive a digital elevation model of the glacier and surrounding topography on which a surface energy balance is computed driven by meteorological data obtained from a meteorological station located on the glacier and a synoptic station maintained at the nearby ny alesund research base given the high resolution topographic data we focus particularly on whether the long duration of sunshine at high latitudes compensates for the higher solar zenith angles on the season long energy balance and whether shading by the surrounding topography plus glacier surface slope and aspect play an increased role in the patterns of solar radiation receipt and hence melt over the glacier surface the model results are validated using a combination of mass balance data from the glacier measured surface lowering at the glacier meteorological station and by comparing a derived energy balance component from the model with a measured energy flux overall the model performance is very good glacier topography is found to play a fundamental role in determining the surface energy balance topographic shading slope and aspect and correction of the surface albedo for high solar zenith angles are found to play a crucial role in determining spatial patterns of surface energy balance and therefore melt

measurement and parameterization of albedo variations at haut glacier d arolla switzerland spatial and temporal variations of surface albedo on haut glacier d arolla switzerland during the 1993 and 1994 ablation seasons are described correlation and regression analyses are used to explain the albedo variations in terms of independent meteorological and surface property variables parameterizations are developed which allow estimation of albedo variation in surface energy balance models snow albedo is best estimated from accumulated daily maximum temperatures since snowfall on deep snow 0 5 cm w e depth a logarithmic function is used while on shallow snow 0 5 cm w e depth an exponential function is used to enable the albedo to decay to the underlying ice or debris albedo the transition from deep to shallow snow is calculated as a function of decreasing snow depth combined r 2 0 65 this new parameterization performs better than earlier schemes because accumulated daily maximum temperatures since snowfall correlate strongly with snow grain size and impurity concentration the main physical controls on snow albedo ice albedo may be parameterized by its relationship to elevation r 2 0 28 but this approach results in only a small improvement over the assumption of a constant mean ice albedo

evolution of cryoconite holes and their contribution to meltwater runoff from glaciers in the mcmurdo dry valleys antarctica cryoconite holes are water filled holes in the surface of a glacier caused by enhanced ice melt around trapped sediment measurements on the ablation zones of four glaciers intaylorvalley antarctica show that cryoconite holes cover about 4 6 of the ice surface they typically vary in diameter from 5 to 145 cm with depths ranging from 4 to 56 cm in some cases huge holes form with 5 m depths and 30 m diameters un like cryoconite holes elsewhere these have ice lids up to 36 cm thick and melt from within each spring about one half of the holes are connected to the near surface hydrologic system and the remainder are isolated the duration of isolation estimated from the chlor ide accumulation in hole waters commonly shows ages of several years with one hole of 10 years the cryoconite holes in the mcmurdo dryvalleys create a near surface hydro logic system tens of cm below the ice surface the glacier surface itself is generally frozen and dry comparison of water levels between holes a few meters apart shows independent cycles of water storage and release most likely local freeze thaw effects control water passage and therefore temporary storage rough calculations indicate that the holes gen erate at least 13 of the observed runoff on the one glacier measured this hydrologic system represents the transition between a melting ice cover with supraglacial streams and one entirely frozen and absent of water abstract cryoconite holes are water filled holes in the surface of a glacier caused by enhanced ice melt around trapped sediment measurements on the ablation zones of four glaciers intaylorvalley antarctica show that cryoconite holes cover about 4 6 of the ice surface they typically vary in diameter from 5 to 145 cm with depths ranging from 4 to 56 cm in some cases huge holes form with 5 m depths and 30 m diameters un like cryoconite holes elsewhere these have ice lids up to 36 cm thick and melt from within each spring about one half of the holes are connected to the near surface hydrologic system and the remainder are isolated the duration of isolation estimated from the chlor ide accumulation in hole waters commonly shows ages of several years with one hole of 10 years the cryoconite holes in the mcmurdo dryvalleys create a near surface hydro logic system tens of cm below the ice surface the glacier surface itself is generally frozen and dry comparison of water levels between holes a few meters apart shows independent cycles of water storage and release most likely local freeze thaw effects control water passage and therefore temporary storage rough calculations indicate that the holes gen erate at least 13 of the observed runoff on the one glacier measured this hydrologic system represents the transition between a melting ice cover with supraglacial streams and one entirely frozen and absent of water

six decades of glacier mass balance observations a review of the worldwide monitoring network glacier mass balance is the direct and undelayed response to atmospheric conditions and hence is among the essential variables required for climate system monitoring it has been recognized as the largest non steric contributor to the present rise in sea level six decades of annual mass balance data have been compiled and made easily available by the world glacier monitoring service and its predecessor organizations in total there have been 3480 annual mass balance measurements reported from 228 glaciers around the globe however the present dataset is strongly biased towards the northern hemisphere and europe and there are only 30 reference glaciers that have uninterrupted series going back to 1976 the available data from the six decades indicate a strong ice loss as early as the 1940s and 1950s followed by a moderate mass loss until the end of the 1970s and a subsequent acceleration that has lasted until now culminating in a mean overall ice loss of over 20 m w e for the period 1946 2006 in view of the discrepancy between the relevance of glacier mass balance data and the shortcomings of the available dataset it is strongly recommended to 1 continue the long term measurements 2 resume interrupted long term data series 3 replace vanishing glaciers by early starting replacement observations 4 extend the monitoring network to strategically important regions 5 validate calibrate and accordingly flag field measurements with geodetic methods and 6 make systematic use of remote sensing and geo informatics for assessment of the representativeness of the available data series for their entire mountain range and for the extrapolation to regions without in situ observations and 7 make all these data and related meta information available

empirical relationships between elevation and the stable isotope composition of precipitation and surface waters considerations for studies of paleoelevation change a compilation of 68 studies from throughout many of the world s mountain belts reveals an empirically consistent and linear relationship between change in elevation and change in the isotopic composition of precipitation along altitudinal transects the isotopic composition of precipitation decreases linearly with increasing elevation in most regions of the world except in the himalayas and at elevations 5000 m there are no significant differences in isotopic lapse rates from most regions of the world 0 28 permil 100 m except at the extreme latitudes where isotopic lapse rates are higher given information on past changes in the isotopic composition of precipitation preserved in pedogenic or authigenic minerals this global isotopic lapse rate can be used to place numerical constraints on the topo graphic development of some ancient mountain belts or plateaus there are many complicating factors that can confound interpretation of paleoel evation change based on stable isotopes and many of these are unique to specific mountain belts or time periods relevant to all stable isotope based paleoelevation change studies is the temperature dependent isotope fractionation between a pedo genic or authigenic mineral and the water from which it forms in cases where isotopic proxy minerals are sampled from localities where temperature will change simulta neously with elevation change the apparent change in the isotopic composition of precipitation may be dampened by several permil this suggests that samples taken from the rainshadow side of an emerging orographic barrier may be more likely to preserve isotopic changes resulting from mountain uplift than samples taken from atop a rising mountain range or plateau

reconstructing middle horizon mobility patterns on the coast of peru through strontium isotope analysis the pre columbian coastal site of ancon peru frequently has been interpreted as an important outpost of the highland wari empire inhabited by individuals from the sierra and the coast in order to test this hypothesis bone tooth pairs from 35 middle horizon 550 ad 1000 ad ancon skeletons were analyzed for strontium isotopes which vary by geologic provenance results indicate that 34 of the 35 individuals have 87 sr 86 sr enamel and bone values higher than ancon s biologically available strontium isotope range nitrogen and carbon isotope data from a subset of the ancon skeletons suggest that the higher than expected 87 sr 86 sr values among the ancon sample likely reflects a diet rich in marine resources rather than migratory activity and highlight the need to use multiple lines of evidence to track residence change at sites where individuals relied on resources other than locally grown terrestrial foods the one remaining individual a young female of elite status has an enamel strontium isotope signature much lower than the available data for local fauna and soil indicating that she was not raised locally her enamel 87 sr 86 sr ratio fits well within the range of strontium isotope values established for the inland wari site of conchopata tung t a knudson k j social identities and geographical origins of wari trophy heads from conchopata peru current anthropology in press and suggests that highland wari immigrants may have been present at ancon during the middle horizon

spatially variable response of himalayan glaciers to climate change affected by debris cover the present state and future evolution of himalayan glaciers has been controversial an analysis of remotely sensed frontal changes and surface velocities from glaciers in the greater himalaya between 2000 and 2008 shows large regional variability in the responses of himalayan glaciers to climate change

internal accumulation on storglaciaren sweden in a multi layer snow model coupled to a distributed energy and mass balance model to investigate the internal accumulation on storglaciaren sweden we couple a multilayer snow model to a distributed energy and mass balance model the snow model describes the temperature density and water content evolution of the snow ice pack and includes the processes of percolation and refreezing of water the model is run for the period 9 may 2 september 1999 and validated against weather station and mass balance observations on the glacier the model performs reasonably well with an average summer mass balance for the location of stake observations of 1 56 m w e compared to 1 59 m w e observed however the amount of melt is overestimated in the higher parts of the accumulation area and underestimated in the lower parts of the ablation area the modelled mass balance is most sensitive to the albedo parameterization the chosen momentum and scalar roughness lengths and all parameters related to snowfall the modelled internal accumulation is 0 25 m w e which amounts to about 20 of the winter accumulation and results in a positive net balance for 1999 of 0 23 m w e the modelled internal accumulation is most sensitive to the initial subsurface temperature profile and the irreducible water content

fault damage zones of the m7 1 darfield and m6 3 christchurch earthquakes characterized by fault zone trapped waves abstract to characterize the subsurface structure of the damage zones caused by the 2010 2011 canterbury earthquake sequence in new zealand s south island we installed two short linear seismic arrays array 1 across the greendale fault gf surface rupture and array 2 over the surface projection of the blind port hills fault phf that ruptured in the 2010 m7 1 darfield and 2011 m6 3 christchurch earthquakes respectively we recorded 853 aftershocks for 4 months after the christchurch earthquake fault zone trapped waves fztws identified at array 1 for aftershocks occurring on both the gf and the phf show that the post s durations of these fztws increase as focal depths and epicentral distances from the array increase suggesting an effective low velocity waveguide formed by severely damaged rocks existing along the gf and phf at seismogenic depths locations of aftershocks generating prominent fztws delineates the subsurface gf rupture extending eastward as bifurcating blind fault segments an additional 5 8 km beyond the mapped 30 km surface rupture into a zone with comparably lower seismic moment release west of the phf rupture which extends westward to within 5 3 1 km of the subsurface gf the propagation of fztw through the intervening gap indicates moderate gf phf structural connectivity we interpret this zone as a fracture mesh reflecting the interplay between basement faults and stress aligned microcracks that enable the propagation of phf sourced fztws into the gf damage zone simulations of observed fztws suggest that the gf rupture zone is 200 250 m wide consistent with the surface deformation width velocities within the zone are reduced by 35 55 with the maximum reduction in the 100 m wide damage core zone corresponding with surface and shallow subsurface evidence for discrete fracturing the damage zone extends down to depths of 8 km or deeper consistent with hypocentral locations and geodetically derived fault models

transmission of solar radiation through clouds on melting glaciers a comparison of parameterizations and their impact on melt modelling we explore the robustness and transferability of parameterizations of cloud radiative forcing used in glacier melt models at two sites in the swiss alps we also look at the rationale behind some of the most commonly used approaches and explore the relationship between cloud transmittance and several standard meteorological variables the 2 m air temperature diurnal range is the best predictor of variations in cloud transmittance however linear and exponential parameterizations can only explain 30 50 of the observed variance in computed cloud transmittance factors we examine the impact of modelled cloud transmittance factors on both solar radiation and ablation rates computed with an enhanced temperature index model the melt model performance decreases when modelled radiation is used the reduction being due to an underestimation of incoming solar radiation on clear sky days the model works well under overcast conditions we also seek alternatives to the use of in situ ground data however outputs from an atmospheric model 2 2 km horizontal resolution do not seem to provide an alternative to the parameterizations of cloud radiative forcing based on observations of air temperature at glacier automatic weather stations conversely the correct definition of overcast conditions is important

seismic imaging of the site response using microearthquake recordings part i method abstract microearthquake signals from widely distributed geographical regions have been noticed repeatedly to be strongly affected by local site effects the corresponding seismograms contain important information on the individual propagation path a single station inversion method is presented which allows the imaging of the subsurface impedance structure from locally recorded sh waves records the technique is based on the kunetz claerbout equation which in its original form states the relationship between the transmission response and the reflection response for p waves in a horizontally layered medium and vertical incidence claerbout 1968 by adapting claerbout9s formulation to the transmission problem for sh waves under oblique incidence microearthquake recordings can be used to calculate corresponding pseudo reflection seismograms which in turn can be inverted for the impedance structure by exploiting levinson recursion limitations in the high frequency content of the signals due to the combined effects of absorption recording system and bandlimited source signals as well as the influence of noise drastically reduce the resolutional power of the inversion procedure a number of different deconvolution techniques have been tested with synthetic seismograms for the applicability to reduce these effects good results have been obtained with the blind deconvolution technique of scherbaum and stoll 1985 utilizing the minimum phase property of the green9s function from the analysis of synthetic data it can be expected that for realistic source receiver situations and short period recording systems the main reflectors down to a depth of several hundreds of meters could be resolved

slowness power spectrum analysis of the coda composition of two microearthquake clusters in northern switzerland abstract the s wave coda composition of two microearthquake clusters in northern switzerland has been analysed using the slowness power spectrum analysis proposed by spudich and bostwick the purpose of this paper is to estimate the directions in which individual coda wavelets leave the source region for lapse times more than six times the s wave travel time the data set consists of 12 and 16 events in the magnitude range of 1 9 2 6 and 1 4 3 4 respectively the depths range from 7 to 8 km and from 6 to 7 km digital data from five vertical component stations enb rbf gef gif and tsb and two three component stations acb and che were available the hypocentral distances to the recording sites vary between 29 and 63 km for the first cluster gunsberg and 10 and 24 km for the second cluster laufelfingen respectively all events have been relocated using a master event technique with inter event arrival times estimated by a cross correlation method the slowness power spectra for the laufelfingen cluster at all stations show essentially two different patterns in agreement with the results of spudich and bostwick we found that the early coda following the direct s wave immediately was composed of wavelets leaving the source region with the same slowness vector as the direct wave we interpret this coda part as being very probably produced close to the recording site however with increasing lapse times we observe a different coda type which receives its energy from wavelets leaving the source region in a variety of directions the transition between the two coda types takes place often at 1 5 2 times and always before three times the s wave arrival time

on the role of subsurface heat conduction in glacier energy balance modelling we discuss the inclusion of the subsurface heat conduction flux into the calculation of the energy balance and ablation at the glacier atmosphere interface data from automatic weather stations are used to force an energy balance model at several locations on alpine glaciers and at one site in the dry andes of central chile the heat conduction flux is computed using a two layer scheme assuming that 36 of the net shortwave radiation is absorbed by the surface layer and that the rest penetrates into the snowpack we compare simulations conducted with and without subsurface heat flux results show that assuming a surface temperature of zero degrees leads to a larger overestimation of melt at the sites in the accumulation area 10 4 13 3 than in the ablation area 0 5 2 8 due to lower air temperatures and the presence of snow the difference between simulations with and without heat conduction is also high at the beginning and end of the ablation season up to 29 for the first 15 days of the season when air temperatures are lower and snow covers the glacier surface while they are of little importance during periods of sustained melt at all the locations investigated

the importance of sea spray to the cation budget of a coastal hawaiian soil a strontium isotope approach soil nutrients such as ca mg and k are traditionally thought to be derived primarily from rock weathering here we show that sea spray is a significant source of nutrient elements to modern and buried soils developed on 30 000 year old pahala ash deposits 50 m from the coast at south point hawaii the soil profiles evolved in a semi arid climate and have always been above sea level and the water table rhizoliths fossilized root traces and horizontal laminated carbonate sheets found in buried soils are composed of high mg calcite up to 14 mol mgco3 differences in strontium isotopic composition between marine aerosols 87sr 86sr 0 7092 and tephra parent material 0 7035 allow quantification of cation sources to the labile soil reservoir and to pedogenic carbonate mixing equations indicate that 50 80 of labile soil sr and approximately half of carbonate sr was derived from marine sources using the sr isotopic signatures and sr ca ratios of seawater and tephra as end members we determined that up to 2 3 of the ca in the labile reservoir and up to 1 3 of ca in the carbonates has a marine origin carbonate 87sr 86sr ratios are fairly constant with depth but labile 87sr 86sr ratios indicate decreasing sea spray aerosol influence with depth this trend could be due either to sequestering of aerosol derived sr in the upper part of the profile or to lower aerosol input in the past due to lower sea level the unusual occurrence of high mg pedogenic calcite probably results from high labile mg ca ratios during earlier stages of weathering coupled with rapid calcite precipitation during soil pore water evaporation

spatial and temporal variability of air temperature on a melting glacier atmospheric controls extrapolation methods and their effect on melt modeling juncal norte glacier chile 1 temperature data from three automatic weather stations and twelve temperature loggers are used to investigate the spatiotemporal variability of temperature over a glacier its main atmospheric controls the suitability of extrapolation techniques and their effect on melt modeling we use data collected on juncal norte glacier central chile during one ablation season we examine temporal and spatial variability in lapse rates lrs together with alternative statistical interpolation methods the main control over the glacier thermal regime is the development of a katabatic boundary layer kbl katabatic wind occurs at night and in the morning and is eroded in the afternoon lrs reveal strong diurnal variability with steeper lrs during the day when the katabatic wind weakens and shallower lrs during the night and morning we suggest that temporally variable lrs should be used to account for the observed change they tend to be steeper than equivalent constant lrs and therefore result in a reduction in simulated melt compared to use of constant lrs when extrapolating from lower to higher elevations in addition to the temporal variability the temperature elevation relationship varies also in space differences are evident between local lrs and including such variability in melt modeling affects melt simulations extrapolation methods based on the spatial variability of the observations after removal of the elevation trend such as inverse distance weighting or kriging do not seem necessary for simulations of gridded temperature data over a glacier

studies of the seismic coda using an earthquake cluster as a deeply buried seismograph array loosely speaking the principle of green s function reciprocity means that the source and receiver positions in a seismic experiment can be exchanged without affecting the observed seismograms consequently the seismograms observed at a single observation location o and caused by a cluster of microearthquakes at locations ei are identical to the time series that would be measured by an array of stress meters emplaced at positions ei recording waves generated by a source acting at o by applying array analysis techniques like slant stacking and frequency wave number analysis to these seismograms we can determine the directions and velocities of the component waves as they travel in the earthquake focal region rather than at the surface we have developed a computationally rapid plane wave decomposition which we have applied to single station recordings of aftershocks of the 1984 morgan hill california earthquake the analysis is applied to data from three seismic stations having considerably different site geologies one is a relatively hard rock station situated on franciscan metamorphics one is within the calaveras fault zone and one is on semiconsolidated sand and gravels we define the early coda to be the part of the coda initiating immediately after the direct s wave and ending at twice the s wave lapse time the character of the s wave and early coda varies from being impulsive at the first station to highly reverberative at the last we examine waves in sequential time windows starting at the s wave and continuing through the early part of the coda at all seismic stations the early coda is dominated by a persistent signal that must be caused by multiple scattering probably within 2 km of each seismic station despite clear station to station differences in the character of the early coda coda q values measured in the late coda greater than twice the s lapse time agree well among stations implying that the mechanisms causing the varying behavior of the early coda do not control the coda decay rate at the stations we have considered coda q values measured on horizontal components of motion agree within a factor of 2 with those measured on vertical components we have not been able to determine the composition of the late coda because of a low signal to noise ratio our analysis technique however is quite appropriate for such a task

migration and mobility at the late lapita site of reber rakival sac watom island using isotope and trace element analysis a new insight into lapita interaction in the bismarck archipelago abstract this paper uses strontium isotope 87 sr 86 sr oxygen isotope 18 o and ba sr trace element data in archaeological tooth enamel samples to investigate migration and mobility at the late lapita site of sac watom island in the bismarck archipelago previous archaeological models have identified lapita mobility at a community level using obsidian distribution patterns and changes in ceramic design whereas isotope and trace element data can potentially reconstruct prehistoric mobility on an individual level human and pig teeth were sampled from sac and a selection of human teeth were included from the late post lapita site of lifafaesing tanga islands as a geographic geological comparison the results indicate that there is a large amount of isotopic variation in the bismarck archipelago which is useful for identifying non local individuals and possibly determining their origins one human individual and several pigs were suggested as coming from elsewhere in the region three potentially separate locations were identified for the non local pigs it is argued using the data from sac that late lapita communities in the bismarck archipelago were more mobile than previously assumed the potential for identifying individual migrants in a lapita context are discussed in terms of assessing the more subtle aspects of lapita society in the southwest pacific islands

migration and viking dublin paleomobility and paleodiet through isotopic analyses abstract during the early medieval period in ireland dublin was established as the largest viking settlement on the island in the ninth century ad a previous biodistance study has suggested that the population of the town consisted of a polyethnic amalgam of immigrant and indigenous in this study we use biogeochemistry to investigate paleomobility and paleodiet in archeological human remains from the ninth to eleventh century levels at the sites at fishamble street ii national museum of ireland excavation number e172 fishamble street iii e190 and john s lane e173 as well as twelfth century remains from wood quay e132 through radiogenic strontium isotope stable oxygen carbon and nitrogen isotope and elemental concentration analyses we investigate the origins of the individuals who lived and died in early and late viking dublin mean archaeological human enamel and bone isotope values from dublin are 87 sr 86 sr 0 70975 0 00139 2 n 22 13 c carbonate v pdb 14 8 0 8 1 n 12 and 18 o carbonate v pdb 7 2 1 0 1 n 12 archaeological human bone samples exhibit mean 13 c collagen v pdb 20 8 0 5 1 n 12 and mean 15 n collagen air 10 0 1 7 1 n 12 comparing these data with archaeological faunal data from dublin and published data from northern europe we argue that there are no clear immigrants from other parts of the north atlantic although there is one clear outlier in both origins and diet overall the relative homogeneity in both paleomobility and paleodiet may support models of acculturation in viking dublin rather than a high number of first generation immigrants or continued migration from scandinavia

a physically based method for estimating supraglacial debris thickness from thermal band remote sensing data in order to account for the effects of debris cover in model scenarios of the response of glaciers to climate change and water resource planning it is important to know the distribution and thickness of supraglacial debris and to monitor its change over time previous attempts to map surface debris thickness using thermal band remote sensing have relied upon time specific empirical relationships between surface temperature and thickness limiting their general applicability in this paper we develop a physically based model that utilizes advanced spaceborne thermal emission and reflection radiometer aster thermal band remotely sensed imagery and is based on a solution of the energy balance at the debris surface the model is used to estimate debris thickness on miage glacier italy and is validated using field debris thickness measurements and a previously published debris thickness map the temporal transferability of the model is demonstrated through successful application to a separate aster image from a different year using reanalysis meteorological input data this model has the potential to be used for regional scale supraglacial debris thickness mapping and monitoring for debris up to at least 0 50 m thickness but improved understanding of the spatial patterns of air temperature aerodynamic roughness length and thermal properties across debriscovered glaciers is needed

recent glacier retreat in the caucasus mountains russia and associated increase in supraglacial debris cover and supra proglacial lake development this paper reports changes in supraglacial debris cover and supra proglacial lake development associated with recent glacier retreat 1985 2000 in the central caucasus mountains russia satellite imagery landsat tm and etm was used to map the surface area and supraglacial debris cover on six neighbouring glaciers in the adylsu valley through a process of manual digitizing on a false colour composite of bands 5 4 3 red green blue the distribution and surface area of supraglacial and proglacial lakes was digitized for a larger area which extended to the whole landsat scene we also compare our satellite interpretations to field observations in the adylsu valley supraglacial debris cover ranges from 25 on individual glaciers but glacier retreat between 1985 and 2000 resulted in a 3 6 increase in the proportion of each glacier covered by debris the only exception to this trend was a very small glacier where debris cover did not change significantly and remote mapping proved more difficult the increase in debris cover is characterized by a progressive up glacier migration which we suggest is being driven by focused ablation and therefore glacier thinning at the up glacier limit of the debris cover resulting in the progressive exposure of englacial debris glacier retreat has also been accompanied by an increase in the number of proglacial and supraglacial lakes in our study area from 16 in 1985 to 24 in 2000 representing a 57 increase in their cumulative surface area these lakes appear to be impounded by relatively recently lateral and terminal moraines and by debris deposits on the surface of the glacier the changes in glacier surface characteristics reported here are likely to exert a profound influence on glacier mass balance and their future response to climate change they may also increase the likelihood of glacier related hazards lake outbursts debris slides and future monitoring is recommended

model study of the spatial distribution of the energy and mass balance of morteratschgletscher switzerland to investigate the spatial distribution of the energy and mass balance fluxes of a glacier a two dimensional mass balance model was developed and applied to morteratschgletscher switzerland the model is driven by meteorological input from four synoptic weather stations located in the vicinity of morteratschgletscher the model results were compared to observations made on the glacier the calculated mean specific mass balance is 0 47 m w e for 1999 and 0 23 m w e for 2000 net shortwave radiation shows a minimum at around 3350 m a s l due to the effects of shading slope aspect reflection from the slopes and obstruction of the sky ignoring these effects results in a 37 increase in the annual incoming shortwave radiation on the glacier causing 0 34 m w e more ablation a 1 c change in the air temperature results in a shift of 0 67 m w e in the mean specific mass balance while altering the precipitation by 10 causes a change of 0 17 m w e

forward waveform modelling procedure for 1 d crustal velocity structure and its application to the southern korean peninsula summary we propose a full grid search procedure for broad band waveform modelling to determine a 1 d crustal velocity model the velocity model can be more constrained because of the use of broad band waveforms instead of traveltimes for the crustal phases although only a small number of event station pairs were employed despite the time consuming nature of the full grid search method to search the whole model parameter space the use of an empirical relationship between the p and s wave velocities can significantly reduce computation time the proposed method was applied to a case in the southern korean peninsula broad band waveforms obtained from two inland earthquakes that occurred on 2007 january 20 mw 4 6 and 2004 april 26 mw 3 6 were used to test the method the three layers over half space crustal velocity model of the p and s wave velocities was estimated comparisons of waveform fitness between the final model and previously published models demonstrate advancements in the average value of waveform fitness for the inland earthquakes in addition 1 d velocity models were determined for three distinct tectonic regions namely the gyonggi massif the okcheon belt and the gyeongsang basin which are all located inside the study area a comparison between the three models demonstrates that the crustal thickness of the southern korean peninsula increases from nw to se and that the lower crustal composition of the okcheon belt differs from that of the other tectonic regions

mass balance estimates for haut glacier d arolla switzerland from 2000 to 2006 using dems and distributed mass balance modeling a distributed mass balance modeling approach is required to assess the impact of future climate scenarios on water availability in glaciated basins accurate estimation of water stored within the snow firn and ice of such basins requires knowledge of the distributed snow and ice mass balance throughout the year in this study we estimate the annual mass balance and runoff for haut glacier darolla switzerland from 2000 to 2006 our estimations are based on observed elevation changes from three digital elevation models dems derived from aerial photographs in september 1999 and 2005 and october 2006 in addition to these estimations we implement a combined field observation and a distributed mass balance modeling approach an energy balance model driven by meteorologi cal variables from automatic weather stations inside the catchment area including gravitational snow transport is run for the period 2005 06 the model results are validated with direct snow water equiv alent measurements as well as with runoff measurements combining the mass balance measurements energy balance calculations and measured runoff we estimate the contribution from ice melt to the runoff for this period to be 25 30 the contribution from snowmelt 50 60 and the contribution from rain 15 25 our model results also show that the snow distribution affects both snow and ice melt it is therefore important for water resources management to understand the distribution of snow in alpine catchments as it seems to be the controlling factor for the timing of streamflow throughout the year as well as for the total availability of water

a distributed surface energy balance model for a small valley glacier i development and testing for haut glacier d arolla valais switzerland this paper describes the development and testing of a distributed surface energy balance model used to calculate rates of surface melting at haut glacier d arolla valais switzerland the model uses a digital elevation model dem of the glacier surface and surrounding topography together with meteorological data collected at a site in front of the glacier to determine hourly or daily totals of the energy balance components and hence of melting over the entire surface of the glacier with a spatial resolutio of 20 m the model can also be used to determine temporal and spatial variations in snow depth snow line position and glacier surface albedo calculations from the model are compared with observations made along the glacier centre line in 1990 and in general the model performs very well the correlation coefficients between calculated and measured snow line elevation albedo and ablation are 0 99 0 85 and 0 81 respectively the main source of error between modelled and measured values of these variables is probably inadequacies in the parameterization of albedo used in the model

short baseline variations in site response and wave propagation effects and their structural causes four examples in and around the santa clara valley california abstract ground motion records of local and regional events from a portable array are used to investigate the structural causes of variations in ground motion over distances of a few hundred meters to a few kilometers in the sedimentary basin environment of the santa clara valley california and its margins arrays of portable seismic stations are used to target four study areas with different ground motion patterns 1 an edge of the alluvial basin extending up onto a marginal ridge blossom hill 2 a cenozoic basin with a nearly flat bottom cupertino basin 3 a long narrow cenozoic basin with a steep v profile evergreen basin and 4 a line perpendicular to the trace of the hayward fault average peak velocities on blossom hill from local earthquakes are a factor of 2 5 times higher than nearby valley sites three dimensional 3d modeling is used to conclude that the majority of the amplification is due to lower shear wave velocities along a local fault zone shannon berrocal site amplification over the cupertino basin in the frequency band 0 5 4 hz is generally low less than 2 0 relative to a mesozoic rock site and spatially uniform this response is attributed to the shallow flat bottomed shape of the basin and the uniform flat laying sedimentary fill in contrast site amplification in the evergreen basin generally exceeds 3 0 and is attributed to the deep v shaped geometry of the basin and younger sedimentary fill 3d waveform modeling shows the elongated shape of the evergreen basin causes more efficient trapping of long period waves for sources along the long axis of the basin a low velocity zone is postulated along the hayward fault with a width between 100 and 200 m based on elevated site response along the fault trace and 4 5 hz fault zone guided waves on the horizontal components of stations near the fault

a general inversion scheme for source site and propagation characteristics using multiply recorded sets of moderate sized earthquakes abstract we derive an inversion scheme that fits the logarithms of seismic body wave spectra to 2 source shapes conditioned by anelastic attenuation with a frequency independent q the residuals from this fit are then projected onto the set of sources and sites with the source terms damped to estimate residual source spectra and site response spectra this two part inversion process is iterated until the square of the residuals summed over frequency for all recordings is minimized the absolute amplitudes of the source and site spectra are determined by fitting the site response spectra to estimates of the site amplification derived from geotechnical data we apply this inversion process to three sets of recordings of loma prieta aftershocks the first data set contains s waves recorded both in the marina district and at nearby hard rock stations we constrain the site response using the s wave velocity measured in a nearby borehole the absolute site amplifications for the marina stations are 15 to 20 at 1 hz and 10 at 2 5 hz the other two data sets comprise the p and s wave recordings from 28 aftershocks ranging in size from m d 2 1 to 4 6 obtained at accelerograph sites near the epicentral area the p and s wave attenuations determined from the inversions are q 414 and 380 while the average near site attenuations are t 0 012 and 0 026 sec respectively the average ratio of the s to p wave seismic moments is 1 1 0 1 the ratio of the p to s wave corner frequencies is 1 24 0 11 and the ratio of s to p wave radiated energy is 13 9 3 2 the brune stress drops for these aftershocks range from 8 to 800 bars the largest earthquakes exhibit the largest stress drops but there is no apparent dependence of stress drop on seismic moment for earthquakes with 10 19 m 0 21 dyne cm

the temporal significance of transitions from melting to calving termini at glaciers in the central southern alps of new zealand termini of valley glaciers in the central southern alps are undergoing a three phase sequence of retreat that began in the 1950s an initial phase of melting and slow downwasting under thickening supraglacial debris mantles is associated with stationary or slowly retreating termini this is followed by a transitional phase of disruption of insulating debris mantles allowing the rapid growth of shallow thermokarst lakes the shape and location of which vary according to glacier gradient and marginal topography a third phase of rapid calving retreat of ice cliffs into deepening proglacial lakes develops from the transitional phase at no stage are terminal responses simply related to climate present transitions to calving retreat are related to the morphology of glacier termini particularly to large outwash heads landform evidence indicates that similar calving phases do not appear to have occurred since late pleistocene deglaciation so that present changes to glacier termini are of great significance

including debris cover effects in a distributed model of glacier ablation 1 distributed glacier melt models generally assume that the glacier surface consists of bare exposed ice and snow in reality many glaciers are wholly or partially covered in layers of debris that tend to suppress ablation rates in this paper an existing physically based point model for the ablation of debris covered ice is incorporated in a distributed melt model and applied to haut glacier d arolla switzerland which has three large patches of debris cover on its surface the model is based on a 10 m resolution digital elevation model dem of the area each glacier pixel in the dem is defined as either bare or debris covered ice and may be covered in snow that must be melted off before ice ablation is assumed to occur each debris covered pixel is assigned a debris thickness value using probability distributions based on over 1000 manual thickness measurements locally observed meteorological data are used to run energy balance calculations in every pixel using an approach suitable for snow bare ice or debris covered ice as appropriate the use of the debris model significantly reduces the total ablation in the debris covered areas however the precise reduction is sensitive to the temperature extrapolation used in the model distribution because air near the debris surface tends to be slightly warmer than over bare ice overall results suggest that the debris patches which cover 10 of the glacierized area reduce total runoff from the glacierized part of the basin by up to 7

the october 17 1989 loma prieta california earthquake and its aftershocks geometry of the sequence from high resolution locations hypocenters of the loma prieta sequence form a dipping zone that rises from the mainshock hypocenter and is parallel to the mainshock nodal plane most aftershocks cluster around the perimeter of the zone surrounding a relatively aseismic center which approximates the region of mainshock rupture at its southeastern end the dipping aftershock zone warps into a vertical surface that corresponds to the san andreas fault in the central and northwestern parts of the zone at depths above 10 km the aftershocks define numerous disjoint fault structures the large component of reverse slip observed in this event agrees with a simple model for slip on a dipping plane within a compressional fault bend we do not believe that the loma prieta earthquake occurred on the sargent fault however we are unable to conclude whether it ruptured the principal plate boundary fault or a less frequently active fault

seismic imaging of the site response using microearthquake recordings part ii application to the swabian jura southwest germany seismic network the subsurface site structure of the swabian jura southwest germany seismic network has been modeled from the inversion of locally recorded sh wave microearthquake seismograms the observed records have been deconvolved from the effects of apparent source pulse broadening due to the combined influence of frequency bandlimited source signals absorption peg leg multiple reflections and the recording system following the procedure of scherbaum and stoll 1985 corresponding pseudo reflection seismograms were calculated based on the kunetz claerbout relation for sh waves and inverted using a levison recursion algorithm the final structural models have been optimized in terms of numbers of layers and depth resolution using ferber s 1985 noise stabilization technique the resulting impedance models for the swabian jura southwest germany seismic network show some strongly correlated reflectors in the uppermost layers which are well understood in terms of the local stratigraphy the comparison of the inverted impedance model hsn with the p wave velocity log from a nearby exploration drilling trochtelfingen beb shows a high degree of similarity of the dominating reflectors down to a depth of several hundred meters as a consequence the coda generating process for the early part of the coda of the observed swabian jura microearthquake seismograms wood anderson magnitude mwa 3 0 can be completely interpreted as an effect of the local subsurface structure

estimation of debris cover and its temporal variation using optical satellite sensor data a case study in chenab basin himalaya debris cover over glaciers greatly affects their rate of ablation and is a sensitive indicator of glacier health this study focuses on estimation of debris cover over samudratapu glacier chenab basin himalaya using optical remote sensing data remote sensing image data of irs 1c liss iii september 2001 irs p6 awifs september 2004 and terra aster september 2004 along with survey of india topographical maps 1963 were used in the study supervised classification of topographically corrected reflectance image data was systematically conducted to map six land cover classes in the glacier terrain snow ice mixed ice and debris debris valley rock and water an accuracy assessment of the classification was conducted using the aster visible near infrared data as the reference the overall accuracies of the glacier cover maps were found to range from 83 7 to 89 1 whereas the individual class accuracy of debris cover mapping was found to range from 82 to 95 this shows that supervised classification of topographically corrected reflectance data is effective for the extraction of debris cover in addition a comparative study of glacier cover maps generated from remote sensing data supervised classification of september 2001 and september 2004 and survey of india topographical maps 1963 has highlighted the trends of glacier depletion and recession the glacier snout receded by about 756 m from 1963 to 2004 and the total glacier area was reduced by 13 7 km 2 from 110 km 2 in 1963 further glacier retreat is found to be accompanied by a decrease in mixed ice and debris and a marked increase in debris cover area the area covered by valley rock is found to increase confirming an overall decrease in the glacier area the results from this study demonstrate the applicability of optical remote sensing data in monitoring glacier terrain and particularly mapping debris cover area

high frequency observations and source parameters of microearthquakes recorded at hard rock sites we have estimated the source parameters of 53 microearthquakes recorded in july 1983 which were aftershocks of the miramichi new brunswick earthquake that occurred on 9 january 1982 these events were recorded by local three component digital seismographs at 400 sps component from 2 hz velocity transducers sited directly on glacially scoured crystalline basement outcrop hypocentral distances are typically less than 5 km and the hypocenters and the seven digital seismograph stations established all lie essentially within the boundaries of a granitic pluton that encompasses the faults that ruptured during the main shock and major aftershocks the p wave velocity is typically 5 km sec at the surface and at least 6 km sec at depths greater than about 1 km the events have s wave corner frequencies in the band 10 to 40 hz and the calculated brune model seismic moments range from 1015 to 1018 dyne cm the corresponding stress drops are generally less than 1 0 bars but there is considerable evidence that the seismic source signals have been modified by propagation and or site effects the data indicate a there is a velocity discontinuity at 0 5 km depth b the top layer has strong scattering attenuating properties c some source receiver paths differentiate the propagated signal d there is a hard rock site p wave f max between 50 and 100 hz and e some hard rock sites are characterized by p wave resonance frequencies in the range 50 to 100 hz comparison of this dataset with the january 1982 new brunswick digital seismograms which were recorded at sites underlain by several meters of low velocity surface sediments suggests that some of the hard rock site phenomena listed above can be explained in terms of a layer over a half space model for microearthquakes this result implies that spectrally determined source dimension scales with site dimension thickness of the layer more generally it emphasizes that it is very difficult to accurately observe the details of seismogenic processes from the earth s surface

shallow structure effects on broadband teleseismic p waveforms the first 5 sec of source equalized p wave receiver functions from an array of broadband portable instruments located about 50 km from the coast in western washington are strongly influenced by very shallow structure depths less than 3 km these data display behavior associated with a dipping high velocity contrast interface at shallow depths the direct p wave and the p to s converted phase vary strongly with backazimuth producing an apparent delay in first arriving energy at western backazimuths these patterns are attributed to a shallow contact between low velocity sandstones at the surface and an underlying high velocity volcanic unit this shallow structure influences even the original unprocessed teleseismic p waves suggesting that such shallow structure could affect other studies such as seismic source analysis utilizing broadband data

modelling seasonal and spatial variations in the surface energy balance of haut glacier d arolla switzerland the impact of spatial and temporal variations in the surface albedo and aerodynamic roughness length on the surface energy balance of haut glacier d arolla switzerland was examined using a semi distributed surface energy balance model arnold and others 1996 the model was updated to incorporate the glacier wide effects of albedo and aerodynamic roughness length variations using parameterizations following brock 1997 after the model s performance was validated the glacier wide patterns of the net shortwave turbulent and melt energy fluxes were examined on four days representative of surface conditions in late may june july and august in the model meteorological conditions were held constant on each day in order that the impact of albedo and aerodynamic roughness length variations could be assessed independently a late summer snowfall event was also simulated albedo and aerodynamic roughness length variations particularly those associated with the migration of the transient snowline and the decay of the winter snowpack were found to exert a strong influence on the magnitude of the surface energy fluxes the importance of meteorological conditions in suppressing the surface energy fluxes and melt rate following a fresh snowfall was highlighted

spatial and temporal melt variability at helheim glacier east greenland and its effect on ice dynamics this is the publisher s version also available electronically from http onlinelibrary wiley com

site response modelling by non linear waveform inversion microearthquake waveforms and spectra are well known to be strongly influenced by the shallow subsurface conditions at the recording site we make use of this fact to determine optimum site models from sh wave microearthquake seismograms using a non linear waveform inversion technique based on simulated annealing site models are optimized in terms of thicknesses s wave velocities and densities of the uppermost layers 100 m for 1d plane layer models in addition the source parameters in terms of brune model source time functions are optimized simultaneously the synthetic seismograms are calculated using a modification of haskell s plane sh wave algorithm using aftershock recordings of the loma prieta earthquake a 1d plane layer model has been obtained for a selected site in central california which has been occupied during the aftershock experiment for this dataset cross correlation coefficients between optimized synthetics and observed records reach values above 0 8 the site model at the selected station for varying sources is fairly stable especially for the uppermost layers we observe systematic variations of layer parameters with back azimuth which would be in agreement with slightly dipping layer interfaces

comparison of a three dimensional model for glacier flow with field data from haut glacier d arolla switzerland a three dimensional finite difference model based on a first order solution of the ice flow equations is applied to haut glacier d arolla switzerland the numerical model successfully converges at horizontal resolutions down to 70 m so a number of detailed comparisons with field data can be made modelled surface velocities with no basal sliding component are compared with surface velocities observed on the glacier over four different time periods the best fit is achieved with over winter surface velocities r 2 0 75 using a rate factor a in glen s flow law of 0 063 a 1 bar 3 surface zones of maximum computed effective stress display a high level of coincidence with observed crevassing the orientation of which is successfully predicted by the direction of the tensile component of the computed principal surface stress comparison of the relative magnitude and direction of computed principal stresses with principal strains measured at the ice surface also correspond closely in an attempt to simulate the observed annual velocity distribution within a cross section of the glacier tongue we incorporate two basal motion patterns into the model by treating net annual ice motion as a time weighted composite of three separate flow situations normal sliding enhanced sliding and no sliding we are able to reproduce the key features of the observed cross sectional ice and basal slip velocity distributions these experiments indicate there may be substantial decoupling taking place along an elongated narrow zone at the bed of haut glacier d arolla and that this decoupling interacts in a complex manner with the englacial stress and strain field

oxygen isotopic analysis of archaeological shells to detect seasonal use of wetlands on the southern pacific coast of mexico abstract oxygen isotopic ratios in modern and archaeological marsh clam shells polymesoda radiata from the acapetahua estuary in southwestern mexico record large scale salinity fluctuations caused by alternating wet and dry seasons thus prehistoric patterns of rainfall can be reconstructed and the season of molluscan death can be estimated changes in the oxygen isotopic patterns preserved in marsh clam shells from late archaic period c 3000 1800 bc archaeological deposits indicate that the season of shellfish harvesting changed dynamically through time in this region based on this study and other lines of archaeological evidence we argue that hunter gatherers during the early stages of the late archaic period visited locations in the littoral zone throughout the year with a focus during dry season months through the late archaic period a general trend occurred toward wet season use of these locations this culminated at the end of the late archaic period with the exclusive use of the littoral zone during wet season months these data indicate a fundamental shift in the way these estuarine locations were being used we argue that people living in this region altered their overall subsistence strategy during the late archaic period due to scheduling conflicts that occurred with the adoption of maize agriculture

spatial and temporal transferability of a distributed energy balance glacier melt model abstract modeling melt from glaciers is crucial to assessing regional hydrology and eustatic sea level rise the transferability of such models in space and time has been widely assumed but rarely tested to investigate melt model transferability a distributed energy balance melt model debm is applied to two small glaciers of opposing aspects that are 10 km apart in the donjek range of the st elias mountains yukon territory canada an analysis is conducted in four stages to assess the transferability of the debm in space and time 1 locally derived model parameter values and meteorological forcing variables are used to assess model skill 2 model parameter values are transferred between glacier sites and between years of study 3 measured meteorological forcing variables are transferred between glaciers using locally derived parameter values 4 both model parameter values and measured meteorological forcing variables are transferred from one glacier site to the other treating the second glacier

climate sensitivity of a high precipitation glacier in new zealand the sensitivity of glaciers to climatic change is key information in assessing the response and sea level implications of projected future warming new zealand glaciers are important globally as an example of how maritime glaciers will contribute to sea level rise a spatially distributed energy balance model is applied to brewster glacier new zealand in order to calculate glacier mass balance run off and sensitivity to climate change the model successfully simulates four annual mass balance cycles close to half 52 of the energy available for melt on the glacier is supplied by turbulent heat fluxes with radiation less important except during the winter model sensitivity to temperature change is one of the largest reported on earth at 2 0 m w e a 1 8c 1 in contrast a 50 change in precipitation is required to offset the mass balance change resulting from a 18c temperature change meltwater run off sensitivity is also very high increasing 60 with a 18c warming the extreme sensitivity of mass balance to temperature change suggests that significant ice loss will occur with even moderate climate warming

planimetric and volumetric glacier changes in the khumbu himal nepal since 1962 using corona landsat tm and aster data multitemporal space imagery from 1962 corona kh 4 1992 landsat tm 2001 and 2005 terra aster was used to investigate the glacier changes in the khumbu himal nepal the ice coverage in the investigation area decreased by about 5 between 1962 and 2005 with the highest retreat rates occurring between 1992 and 2001 the debris coverage increased concomitantly with the decrease in total glacier area the clean ice area decreased by 10 digital terrain model dtm generation from the early corona kh 4 stereo data in this high relief terrain is time consuming and the results still contain some elevation errors however these are minor in the snow free areas with gentle slopes thus comparison of the surfaces of the debris covered glacier tongues based on the corona dtm and an aster dtm is feasible and shows the downwasting of the debris covered glaciers the highest downwasting rates more than 20 m 0 5 m a 1 can be found near the transition zone between the active and the stagnant glacier parts of the debris covered glacier tongues the downwasting is lower but still evident in the active ice areas and at the snout with thick debris cover all investigated debris covered glaciers in the study area show similar behaviour the estimated volume loss for the investigated debris covered glacier tongues is 0 19 km 3

an enhanced temperature index glacier melt model including the shortwave radiation balance development and testing for haut glacier d arolla switzerland an enhanced temperature index glacier melt model incorporating incoming shortwave radiation and albedo is presented the model is an attempt to combine the high temporal resolution and accuracy of physically based melt models with the lower data requirements and computational simplicity of empirical melt models represented by the degree day method and its variants the model is run with both measured and modelled radiation data to test its applicability to glaciers with differing data availability five automatic weather stations were established on haut glacier d arolla switzerland between may and september 2001 reference surface melt rates were calculated using a physically based energy balance melt model the performance of the enhanced temperature index model was tested at each of the four validation stations by comparing predicted hourly melt rates with reference melt rates predictions made with three other temperature index models were evaluated in the same way for comparison the enhanced temperature index model offers significant improvements over the other temperature index models and accounts for 90 95 of the variation in the reference melt rate the improvement is lower but still significant when the model is forced by modelled shortwave radiation data thus offering a better alternative to existing models that require only temperature data input

site response estimation from earthquake data abstract aftershocks of the 1989 loma prieta california earthquake are used to estimate site response along the san francisco peninsula a total of 215 shear wave records from 24 sources and 21 sites are used in a linear inversion for source and site response spectra the methodology makes no assumptions about the shape of the source spectrum however to obtain a stable unique inverse a q model and geometrical spreading factor are assumed as well as a constraint on site response that sets the site response averaged over two specific stations to 1 0 site responses calculated by this formulation of the problem are compared with other studies in the same region that use different methodologies and or data the shear wave site responses compare favorably with estimates based on an 2 constrained source model comparison with coda amplification factors is not as close but still favorable considering that the coda values were determined for nearby locations with similar geology and not the same sites the degree of agreement between the three methods is encouraging considering the very different assumptions and data used

an energy balance model for debris covered glaciers including heat conduction through the debris layer extensive covers of supraglacial debris are often present in glacier ablation areas and it is essential to assess exactly how the debris affects glacier melt rates this paper presents a physically based energy balance model for the surface of a debris covered glacier the model is driven by meteorological variables and was developed using data collected at miage glacier italy during the ablation seasons of 2005 2006 and 2007 the debris surface temperature is numerically estimated by considering the balance of heat fluxes at the air debris interface and heat conduction through the debris is calculated in order to estimate melt rates at the debris ice interface the predicted hourly debris surface temperatures and debris internal temperatures provide a good fit to temperatures measured on rock covered miage glacier r 2 0 94 and the tephra covered glacier on villarrica volcano chile r 2 0 82 the model can also be used to reproduce observed changes in melt rates below debris layers of varying types and thicknesses an important consideration for the overall mass balance of debris covered glaciers

determining the local 87sr 86sr range for archaeological skeletons a case study from neolithic europe measurement of strontium isotopes in archaeological skeletons is an effective technique for characterizing prehistoric mobility however interpretation of the results can be highly sensitive to small changes in the determined local 87sr 86sr signature at an archaeological site because the local range is often defined as within 2 s d from the mean 87sr 86sr value in archaeological human bones the susceptibility of bones to diagenesis may lead to significant overestimates in the number of non locals at a particular site tooth enamel on the other hand is highly resistant to postmortem biochemical alteration and it is found that 87sr 86sr in archaeological enamel samples from animals of neolithic germany provide a useful alternative estimate for the local range

boundary layer integration approach to advection of sensible heat to a patchy snow cover in the calculation of the melting of a patchy snow cover the energy advected from the adjacent bare soil to the snow surface is an important consideration the quantity or rate of energy advected depends on the fetches and sizes of snow and bare ground patches any successful method to estimate advection will necessarily require the incorporation of relationships describing the same complex boundary layer methods require detailed spatial knowledge of the patch sizes wind direction and fetch distances and are computationally intensive a physically based approach that can be spatially applied using distributions of snow patch geometry is required this paper presents a new approach in which boundary layer integration is used to provide a means of calculating the amount of energy removed by the snow patch surface as warmer air moves over it the method is reduced to a simple parametric form and the relationships describing the coefficients required for its application are developed the applicability of this new approach is discussed in light of the fractal nature of snow patches the relationship between the individual patch length and area and the distribution of patch sizes as they develop and disappear on the landscape

calculating ice melt beneath a debris layer using meteorological data generalized numerical models of sub debris ice ablation are preferable to empirical approaches for predicting runoff and glacier response to climate change as empirical methods are site specific and strongly dependent upon the conditions prevailing during the measurement period we present a modified surface energy balance model to calculate melt beneath a surface debris layer from daily mean meteorological variables despite numerous simplifications the model performs well and modelled melt rates give a good match to observed melt rates suggesting that this model can produce reliable estimates of ablation rate beneath debris layers several decimetres thick this is a useful improvement on previous models which are inappropriate for thick debris cover

ground motion at the san francisco international airport from the loma prieta earthquake sequence 1989 abstract following the loma prieta earthquake the u s geological survey installed four portable digital seismic recorders at the san francisco international airport sfo for one week to study aftershock ground motion at this important bay area lifeline this study was motivated largely by the need to anticipate strong ground motion from future major earthquakes affecting the bay area and to a lesser extent by the fact that sfo was shut down for 13 hours owing to damage from the loma prieta shock accordingly the recording sites were chosen so as to elucidate the effects of varying thicknesses of low velocity surficial alluvium on the ground motion three large aftershocks with magnitudes ranging from 4 2 to 4 5 each produced ground motion that was recorded at all four sfo stations one of our stations was collocated with a permanent ground motion recorder that indicated a peak horizontal velocity of 29 cm sec and a peak horizontal acceleration of 0 33 g during the 18 october mainshock from the aftershock data and one mainshock record it is possible to extrapolate approximately the mainshock ground motion to other locations at sfo and more generally to assess the effects of low velocity sedimentary cover including artificial fill material on the character of the ground motion the main shock ground motion recorded at the permanent station was apparently typical for most of sfo where the near surface alluvium resulted in peak horizontal ground velocity in the frequency band 0 1 to 3 hz amplified by a factor of about 2 5 relative to that recorded at bedrock sites observations in the epicentral distance range 59 to 95 km including sfo of the moho reflected phases pmp and sms from the aftershocks support the hypothesis presented elsewhere that the phase sms accounted for much of the peak ground motion throughout most of the san francisco bay area