predictions of changes of glacier mass balance in the nepal himalaya and tibetan plateau a case study of air temperature increase for three glaciers

teleseismic detection of a slow precursor to the great 1989 macquarie ridge earthquake low frequency spectra for the 1989 macquarie ridge earthquake magnitude 8 2 show an amplitude increase and a phase delay decrease below 6 millihertz that require a short term slow precursor this earthquake can be modeled as a compound event in which a fast rupturing ordinary earthquake was initiated by an episode of slow smooth deformation that began more than 100 seconds before the main shock the moment released in the slow precursor was large about 3 x 10 20 newton meters equivalent to an event of magnitude 7 6 the data are consistent with the precursor being generated in a region of the oceanic upper mantle below the main rupture

effect of catchment scale subsurface mixing on stream isotopic response a 3 8 ha watershed on the west coast of new zealand was instrumented with suction lysimeters and automatic water samplers to determine the relationship between subsurface isotopic and chemical concentrations to those of rainfall and resulting streamflow a t test showed that 2 represented a significant difference between successive sample deuterium values eleven rainfall episodes were subdivided into two categories 1 two events where stream isotopic composition did not deflect 2 from prestorm values and 2 four events which demonstrated new water flushing detailed analysis of one 47 mm rainfall 9 8 mm runoff event showed that old water dominated stream water exiting the watershed by 90 using a standard two component hydrograph separation for deuterium corroborated by cl and electrical conductivity three component hydrograph separation indicated that 12 16 was in the form of soil water with 5 as on channel precipitation and 80 groundwater analysis of over 1000 water samples revealed systematic trends in soil water and groundwater isotopic composition both in a downslope and downprofile direction between storm suction lysimeter deuterium data showed a systematic dampened response to temporally variable rainfall deuterium concentrations multivariate cluster analysis revealed three distinct soil water groundwater groupings with respect to soil depth and geographic position within the watershed within storm suction lysimeter sampling preserved similar groupings indicating that the subsurface reservoir is poorly mixed on short time scales understanding subsurface mixing response to rainfall should greatly improve models of episodic stream response and partitioning of storm flow into waters of different age

characterizing swells in the southern pacific from seismic and infrasonic noise analyses a temporary network of 10 broad band seismic stations has been installed in french polynesia for the polynesian lithosphere and upper mantle experiment plume all the seismic stations were installed either on volcanic islands or on atolls of the various archipelagos of french polynesia in a manner which complements the geographic coverage provided by the regional permanent stations the primary aim of plume is to image the upper mantle structures related to plate motion and hotspot activity however because of its proximity to all sites the ocean is responsible for a high level of noise in the seismic data and we show that these data can also be used to analyse ocean wave activity the power spectral density psd analyses of the seismic data recorded in french polynesia show clear peaks in the 0 05 0 10 hz band periods between 10 and 20 s which corresponds to swell frequencies clear peaks in this frequency band are also observed in infrasonic data recorded on tahiti ground motion analysis shows that the swell related seismic noise srsn is linearly polarized in the horizontal plane and its amplitude decreases rapidly with the distance from the shore the microseismic and the infrasonic noise amplitudes show very similar variations from station to station and both are strongly correlated with the swell amplitudes predicted by the national oceanic and atmospheric administration noaa wind forced wavewatch models the swell direction can be estimated from srsn polarization analysis but this has to be done with care since for some cases the ground motions are strongly controlled by the islands anisometric shapes and by swell refraction processes we find cases however such as tahiti or roughly circular tuamotu atolls where the azimuth of the swell is in good agreement with the seismic estimates we therefore demonstrate that the srsn and the infrasonic signal observed in french polynesia can be used in such cases as a proxy for swell amplitude and azimuth from the continuous analysis of the data recorded in 2003 at the permanent seismic station pptl in tahiti transfer functions have been obtained this could provide a way to quantify the swell activity during the last two decades and therefore assist in the investigation of climate changes

soil moisture content estimation using ground penetrating radar reflection data abstract ground penetrating radar gpr reflection travel time data were used to estimate changes in soil water content under a range of soil saturation conditions throughout the growing season at a california winery data were collected during three data acquisition campaigns over an 80 by 180 m area using 100 mhz surface gpr antennas gpr reflections were associated with a thin low permeability clay layer located 0 8 1 3 m below the ground surface that was identified from borehole information and mapped across the study area field infiltration tests and neutron probe logs suggest that the thin clay layer inhibited vertical water flow and was coincident with high volumetric water content vwc values the gpr reflection two way travel time and the depth of the reflector at the borehole locations were used to calculate an average dielectric constant for soils above the reflector a site specific relationship between the dielectric constant and vwc was then used to estimate the depth averaged vwc of the soils above the reflector compared to average vwc measurements from calibrated neutron probe logs over the same depth interval the average vwc estimates obtained from gpr reflections had an rms error of 0 018 m3 m 3 these results suggested that the two way travel time to a gpr reflection associated with a geological surface could be used under natural conditions to obtain estimates of average water content when borehole control is available and the reflection strength is sufficient the gpr reflection method therefore has potential for monitoring soil water content over large areas and under variable hydrological conditions

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

low frequency source characteristics of the great 1960 chilean earthquake the low frequency nature of the great 1960 chilean earthquake the earth s largest recorded event is characterized and a source model composed of three events with a combined seismic moment of 5 5 1023 n m and a duration of 1500 s is presented the results show conclusively that large scale slip which is only observed at low frequencies preceded the main shock complex amplitude measurements of normal mode data in the band 1 0 5 0 mhz recorded at eight vertical component stations comprise the data set in this band the earthquake source is assumed to be described by a line source propagating at a constant rupture velocity the data set is the basis for a sequence of least squares inversions to determine the seismic moment rupture velocity spatial slip distribution and the temporal slip function the data are best explained by a source model that begins 1150 s before the main shock with an event of moment 1 9 1023 n m and rise time of 300 s a main shock with moment of 3 2 1023 n m and for which most of the low frequency energy was released beginning about 50 s after the short period origin time and an event 350 s later with moment of 0 4 1023 n m the uncertainty in the moment estimate of the great 1960 chilean earthquake is about 50 and is due primarily to the probable range of fault plane dip which is not well constrained at this time

assessing vertical soil moisture dynamics using multi frequency gpr common midpoint soundings summary soil moisture measurement techniques are of utmost importance to vadose zone hydrologists surface hydrogeophysical methods such as ground penetrating radar gpr have the capacity to provide field scale soil moisture information across a range of depth scales this paper presents an extensive field study using multi frequency i e 225 mhz 450 mhz 900 mhz gpr common midpoint cmp soundings to monitor a complete annual cycle of soil moisture conditions at three distinct sites we examine the use of normal moveout nmo velocity analysis applied to cmp data for monitoring highly dynamic vertical soil moisture conditions in a mid latitude climate consisting of wetting drying and freeze thaw cycles with varying degrees of magnitude and vertical velocity gradient nmo velocity analysis is used to construct interval velocity depth models at a fixed location collected every 1 4 weeks these time lapse models are combined to construct temporal interval velocity fields which are converted into soil moisture content using an appropriate petrophysical relationship using these moisture fields we were able to characterize the vertical distribution and dynamics of soil moisture in the shallow vadose zone although the use of multiple antenna frequencies provided varying investigation depths and vertical resolving capabilities optimal characterization of soil moisture conditions was obtained with high frequency 900 mhz antennas the integration of direct ground wave and nmo velocity data from a single cmp sounding allowed us to better refine the shallow soil moisture profile and underlying vadose zone conditions during seasonal wetting drying and freezing cycles this study demonstrates the capacity of gpr to characterize vertical moisture dynamics and highlights the importance of collecting high resolution data along the air soil interface to resolve the water content profile from the surface down to the deeper vadose zone conditions

travel times in the vadose zone variability in space and time water travel times reflect hydrological processes yet we know little about how travel times in the unsaturated zone vary with time using the soil physical model hydrus 1d we derived time variable travel time distributions for 35 study sites within the attert catchment in luxembourg while all sites experience similar climatic forcing they differ with regard to soil types 16 cambisols 12 arenosols and 7 stagnosols and the vegetation cover 29 forest and 6 grassland we estimated site specific water flow and transport parameters by fitting the model simulations to observed soil moisture time series and depth profiles of pore water stable isotopes with the calibrated model we tracked the water parcels introduced with each rainfall event over a period of several years our results show that the median travel time of water from the soil surface to depths down to 200 cm is mainly driven by the subsequent rainfall amounts the median time until precipitation is taken up by roots is governed by the seasonality of evapotranspiration rates the ratio between the amount of water that leaves the soil profile by on the one hand and evaporation and transpiration on the other hand also shows an annual cycle this time variable response due to climatic forcing is furthermore visible in the multimodal nature of the site specific master transit time distribution representing the flow averaged probability density for rainwater to become recharge the spatial variability of travel times is mainly driven by soil texture and structure with significant longer travel times for the clayey stagnosols than for the loamy to sandy cambisols and arenosols

digital terrain modelling a review of hydrological geomorphological and biological applications the topography of a catchment has a major impact on the hydrological geomorphological and biological processes active in the landscape the spatial distribution of topographic attributes can often be used as an indirect measure of the spatial variability of these processes and allows them to be mapped using relatively simple techniques many geographic information systems are being developed that store topographic information as the primary data for analysing water resource and biological problems furthermore topography can be used to develop more physically realistic structures for hydrologic and water quality models that directly account for the impact of topography on the hydrology digital elevation models are the primary data used in the analysis of catchment topography we describe elevation data sources digital elevation model structures and the analysis of digital elevation data for hydrological geomorphological and biological applications some hydrologic models that make use of digital representations of topography are also considered

estimation of snow and glacial melt contribution through stable isotopes and assessment of its impact on river morphology through stream power approach in two himalayan river basins the impact of increased temperature on the third pole as the himalayas is referred to and the likely cascading impacts on the general downstream hydrology have been widely noted however the impact on fluvial geomorphology has not received specific attention change in the glacial domain in terms of melt increase will change discharge and sediment flux into fluvial system which will induce changes in fluvial processes and forms the present work attempts to study this process based glacio fluvial coupling in the two neighbouring glaciated river basins in the northwest himalaya viz the sutlej and the yamuna river basins till the mountain front a total of 194 samples of river tributary and groundwater of pre and post monsoon seasons in the two river basins were analysed for stable isotopes the trend of 18o and electrical conductivity along the mainstream gives qualitative idea on the influence of headwaters in the downstream of the catchment thereby allowing inference on melt contribution further two component mixing model using stable oxygen isotope of two seasons water samples showed that melt contributes about 41 1 66 8 and 6 6 10 6 at different points to the total river discharge in the sutlej and the tons river the glaciated major tributary of the yamuna river basins respectively for different scenarios of increase in melt stream power increase in the sutlej river basin is significant as opposed to the tons river river channel in the sutlej river basin will be significantly more impacted in comparison with the yamuna river system

stable isotopes in the source waters of the yamuna and its tributaries seasonal and altitudinal variations and relation to major cations water samples from the yamuna and its tributaries one of the major river systems draining the himalaya have been analysed for their stable oxygen and hydrogen isotopes during three seasons summer monsoon and post monsoon the data show clear seasonal and altitudinal variations waters from higher altitudes and those collected during monsoon season are characterized by relatively depleted isotopic composition regression analysis of d 18 o data of samples collected during summer and monsoon seasons shows that the slope of the best fit lines are nearly identical to those of precipitation at new delhi for the same period the similarity in their slopes suggests that the isotopic composition of precipitation contributing water to these rivers are reasonably well preserved in both monsoon and non monsoon seasons however during the non monsoon period both rainfall and river waters carry signatures of evaporation the deuterium excess in river waters during the three seasons though overlap with each other the values during october are higher this can be understood in terms of recycled moisture contributions to precipitation the altitude effect for 18 o in these waters is determined to be 0 11 per 100 m a factor of about two less than that reported for the ganga source waters from similar altitudinal range the variability in altitude effects in rivers draining the himalaya seems to be controlled by the amount effect associated with the monsoon the significant spatial variability in altitude effect in these river basins which are a few hundred kilometers apart suggests that reconstruction of palaeoelevation in the himalaya based on 18 o altitude gradients would depend critically on its proper assessment in the region this study has established a relationship between total cation abundance and 18 o in waters of the yamuna mainstream total cations corrected for cyclic components double for a 1 4 km decrease in altitude as the yamuna flows downstream

review and comparison of models for describing non equilibrium and preferential flow and transport in the vadose zone abstract in this paper we review various approaches for modeling preferential and non equilibrium flow and transport in the vadose zone existing approaches differ in terms of their underlying assumptions and complexity they range from relatively simplistic models to more complex physically based dual porosity dual permeability and multi region type models a relatively simple dual porosity flow model results when the richards equation is combined with composite double hump type equations for the hydraulic properties to account for both soil textural matrix and soil structural fractures macropores peds effects on flow the simplest non equilibrium flow model a single porosity model which distinguishes between actual and equilibrium water contents is based on a formulation by ross and smettem soil sci soc am j 64 2000 1926 that requires only one additional parameter to account for non equilibrium a more complex dual porosity mobile immobile water flow model results when the richards or kinematic wave equations are used for flow in the fractures and immobile water is assumed to exist in the matrix we also discuss various dual permeability models including the formulation of gerke and van genuchten water resour res 29 1993a 305 and the kinematic wave approach as used in the macro model of jarvis technical description and sample simulations department of soil science swedish university of agricultural science uppsala sweden 1994 51 both of these models invoke terms accounting for the exchange of water and solutes between the matrix and the fractures advantages and disadvantages of the different models are discussed and the need for inter code comparison is stressed especially against field data that are sufficiently comprehensive to allow calibration validation of the more complex models and to distinguish between alternative modeling concepts several examples and comparisons of equilibrium and various non equilibrium flow and transport models are also provided

assessment of snowmelt runoff modelling and isotope analysis a case study from the western himalaya india the major river systems of india i e the indus ganga and brahmaputra river systems originating in the himalayan region are considered the lifeline of the indian subcontinent the main sources maintaining the flow of the himalayan rivers are snow glacial melt runoff rainfall runoff and base flow the beas river originates from beas kund glacier in the himalayan region and flows down to join the sutlej river which is a tributary of the indus river system in the present study two approaches namely hydrologic modelling and isotope analysis have been applied to estimate the contribution of snow and glacier melt samples of streamflow rainfall and snow for isotopic analysis were collected daily from april to september and weekly from october to march during 2010 and 2011 the isotope analysis of samples reveals that the snow glacier melt contribution to the beas river at manali is 50 of the total flow during these 2 years snowmelt runoff modelling has been carried out using the snowmod model and the snow glacier melt runoff contribution is calculated to be 52 of the total flow during the same period these findings indicate that the results obtained from the two approaches are similar

teleseismic search for slow precursors to large earthquakes some large earthquakes display low frequency seismic anomalies that are best explained by episodes of slow smooth deformation immediately before their high frequency origin times analysis of the low frequency spectra of 107 shallow focus earthquakes revealed 20 events that had slow precursors 95 percent confidence level 19 were slow earthquakes associated with the ocean ridge transform system and 1 was a slow earthquake on an intracontinental transform fault in the east african rift system these anomalous earthquakes appear to be compound events each comprising one or more ordinary fast ruptures in the shallow seismogenic zone initiated by a precursory slow event in the adjacent or subjacent lithosphere

a new triangular multiple flow direction algorithm for computing upslope areas from gridded digital elevation models 1 gridded digital elevation data often referred to as dems are one of the most widely available forms of environmental data topographic analysis of dems can take many forms but in hydrologic and geomorphologic applications it is typically used as a surrogate for the spatial variation of hydrological conditions topographic indices and flow routing here we report on a new flow routing algorithm and compare it to three common classes of algorithms currently in widespread use the advantage of the new algorithm is that unrealistic dispersion on planar or concave hillslopes is avoided whereas multiple flow directions are allowed on convex hillslopes we suggest that this new triangular multiple flow direction algorithm md1 is more appropriate for a range of flow routing and topographic index applications

earthquake precursors in japan precursor time and detectability abstract earthquake precursor data amounting to 418 in number accumulated in japan are analyzed most data are obtained under the nation wide earthquake prediction programme the precursor time t versus main shock magnitude m relationship is different for different groups of precursors a linear relation such as log t a bm where a and b are constants seems to hold for precursor disciplines such as land deformation revealed by geodetic survey and tide gauge observation ground tilt observed by a water tube tiltmeter anomalous seismic activity and geomagnetic field change although a similar relationship seems to hold for the disciplines of earth currents radon concentration underground water etc the precursor time is substantially smaller for these disciplines than for the former disciplines the above characteristics of precursor time suggests that precursors closely connected to the dilatancy generation seem to be observed at an earlier stage of seismogenetic activity precursors probably associated with diffusion of underground water into the dilatant region seem to follow for a number of precursor disciplines such as foreshock ground tilt observed by a pendulum tiltmeter resistivity by a variometer and so on no dependence of t on m is found the relationship between m and the logarithmic epicentral distance d measured in kilometers is different from discipline to discipline relying on empirical and theoretical studies of coseismic strain step it turns out that precursors found by geodetic and geomagnetic observations seem to reflect a crastal strain of the order of 10 7 10 6 precursors obtained by a resistivity variometer seem to represent a strain of the order of 10 9 10 8 precursors of other disciplines seem to correspond to a strain of 10 8 10 7 it is clear that precursors can be detected further from the epicenter as the main shock magnitude becomes larger in some favourable cases a precursor can be observed even where the epicentral distance is several times larger than that of the epicentral area

characteristics of soil water movement in a grass slope in a karst peak cluster region china soil water is very important in hilly areas with thin soil layers and deep groundwater tables such as the karst peak cluster region of southwest china an investigation into soil water movement can provide insights into management of shallow water resources and soil nutrients as well as prevention of groundwater pollution in this study o 18 and h 2 tracers were used to trace soil water movement in planar soil mass type microhabitats in the middle part of a steep hillslope covered by grasses in a karst peak cluster region of china from may 2008 to july 2009 samples of precipitation and two types of soil water which had different integrated degrees of mobility and were of different depth intervals or depths were collected the hydrogeochemical characteristics were compared between precipitation and soil water and these data were applied in convolution based lumped parameter models our results indicated that vertical piston flow rather than lateral flow along the soil bedrock interface played an important role in soil water percolation at least in the upper soil layer approximately 7cm over the permeable bedrock the mixing effect and preferential flow might also play a role in soil water percolation in general the evaporation effect on soil water was weak except for the uppermost 10cm soil matrix water during winter the lower limits of mean transit time of soil matrix flow passing through 5 15 25 35 and 41 5cm depths were 4 81 7 70 16 19 21 85 and 27 44days respectively our study demonstrated the crucial functions of the soil reservoir in regulating the water cycle and could provide guidance on conservation of soil water and hydrological studies the applied method was proved to be a suitable approach for investigating soil water movement on a monthly scale

ecohydrological separation in wet low energy northern environments a preliminary assessment using different soil water extraction techniques ecohydrological studies in seasonally dry climatic regions have revealed isotopic separation of the sources of water used by trees and those that generate stream flow also referred to as the two water worlds hypothesis here we investigated whether similar separation occurs in a wet low energy northern latitude 57 environment in scotland for two common soil types histosols and podzols at three soil depths and at both forested with scots pine pinus sylvestris and non forested sites we compared the stable isotope composition of soil water held at increasing soil water tensions these were assessed by different soil water extraction techniques rhizon samplers mobile water centrifugation at different speeds representing different tensions and cryogenic extraction bulk water sampling occurred during a relatively dry summer water that was held at increasing tensions appeared more depleted than more mobile water consistent with older winter precipitation this pattern was independent of soil type vegetation cover and time during the growing season although there was a slight tendency towards less separation with soil depth nevertheless soil waters in this generally wet low energy environment exhibited only minor evaporative enrichment limited to the upper soil profile only furthermore stream water showed no deviation from the local meteoric water line preliminary sampling for tree xylem water suggested uptake of evaporated soil water from the near surface soil horizons upper 10 cm where fine root densities are concentrated for histosols in particular tree water appeared lagged in its isotopic composition compared to the soil water time series although more work is needed to fully test the two water worlds hypothesis our initial analyses did not provide clear evidence to support this in wet low energy northern environments copyright 2015 john wiley sons ltd

spatial and temporal dynamics of water flow and solute transport in a heterogeneous glacial till the application of high resolution profiles of δ18o and δ2h in pore waters summary the heterogeneity and dynamic of water flow and solute transport processes were investigated in the upper 6 m of a surficial glacial till in southern saskatchewan canada continuous core samples from three vertical sites located over a maximum spatial distance of 65 m were collected and analyzed for particle size distribution porosity and water content high resolution 0 2 m profiles of 18o and 2h in pore waters were also measured for the three sites on a seasonal basis depth profiles of all measured parameters indicate highly heterogeneous structures in the upper 6 m in two coreholes depleted water isotopes measured at different depths below ground 0 7 and 3 m were in the range of winter precipitation values suggesting preferential flow of meltwater in spring accompanied by a rising water table a one dimensional equilibrium flow and transport model failed to simulate the isotope depth distributions with depleted winter values and could not reproduce the measured values even when accounting for vertical preferential flow a conceptual model was created based on the consistency of all measured data and assuming preferential lateral flow as the controlling flow and transport mechanism after snowmelt in the model water from surface runoff after snowmelt drains into an ephemeral depression that crosses the study site as this water infiltrates it forms a water table mound that slowly propagates away from the depression as the water table propagates outwards dynamic vertical flow processes result in net upward and downward fluxes

process identification at a slow moving landslide in the vorarlberg alps a fine grained slope that exhibits slow movement rates was investigated to understand how geohydrological processes contribute to a consecutive development of mass movements in the vorarlberg alps austria for that purpose intensive hydrometeorological hydrogeological and geotechnical observations as well as surveying of surface movement rates were conducted during 1998 2001 subsurface water dynamics at the creeping slope turned out to be dominated by a three dimensional pressure system the pressure reaction is triggered by fast infiltration of surface water and subsequent lateral water flow in the south western part of the hillslope the related pressure signal was shown to propagate further downhill causing fast reactions of the piezometric head at 5 5 m depth on a daily time scale the observed pressure reactions might belong to a temporary hillslope water body that extends further downhill the related buoyancy forces could be one of the driving forces for the mass movement a physically based hydrological model was adopted to model simultaneously surface and subsurface water dynamics including evapotranspiration and runoff production it was possible to reproduce surface runoff and observed pressure reactions in principle however as soil hydraulic functions were only estimated on pedotransfer functions a quantitative comparison between observed and simulated subsurface dynamics is not feasible nevertheless the results suggest that it is possible to reconstruct important spatial structures based on sparse observations in the field which allow reasonable simulations with a physically based hydrological model copyright 2004 john wiley sons ltd

episodic aseismic earthquake precursors shallow earthquakes are generally believed to be brittle fractures in a stressed medium with rupture velocity at a speed close to that for shear waves we know however that the earth allows failure over a wide range of timescales creep events occur on the san andreas fault system and for some earthquakes the high speed rupture is accompanied by a slower process1 5 here we report on episodic slow events which occurred before the japan sea earthquake of magnitude 7 7 on 26 may 1983 a sacks evertson borehole strain meter6 90 km from the earthquake recorded about 100 aseismic strain events in a five month period before and immediately following the earthquake none has been detected after the large aftershocks the observed signals are consistent with a precursory redistribution of stress through aseismic slip on a deep extension of the main shock fault plane such episodic aseismic events may provide a mechanism for relatively rapid stress concentration before earthquakes

an isotopic and geochemical study of snowmelt runoff in a small arctic watershed old water contributions to snowmelt runoff in a stream can be defined as water which was stored in the catchment prior to the start of the runoff event in question we used mass balance techniques for natural oxygen 18 and several chemical parameters electrical conductivity ca and mg to estimate the magnitude and timing of old water contributions to snowmelt runoff in the apex river watershed during the 1983 field season the apex river catchment is located in the southern part of baffin island northwest territories canada the watershed has an area of 60 km2 it is in the zone of continuous permafrost and the geology is dominantly precambrian gneiss with sporadic thin glacial overburden the isotopic data indicate that for the snowmelt season of 1983 third highest peak discharge of 11 years of record approximately 50 per cent of the peak stream discharge consisted of old water our data also suggest that about 60 per cent of the entire 1983 hydrograph was old water the chemical parameters give old water contributions which are at least 10 per cent less than the isotopically derived estimate but they are consistent with the isotopic estimate during peak flow

beginnings of earthquakes in the mexican subduction zone on strong motion accelerograms abstract the guerrero mexico accelerograph network has recorded at short distances earthquakes with magnitudes from 3 0 to 8 1 in this article the initial 3 5 sec of the p waves on the vertical component are compared in addition to unfiltered accelerograms several causal bandpass filters are applied we do not see significant differences in either original or filtered records between the initial e g 0 5 sec seismograms of moderate and large earthquakes in the original and 2 to 5 hz passband the main differences among events with magnitudes over about 4 5 is in the duration of shaking the initial ground motions of all the large events have very small amplitudes which gradually get larger at lower frequencies seismograms of the largest events show a complex series of multiple pulses assumed related to failure of numerous asperities in our lowest frequency band 0 2 to 0 5 hz most of the large events that we examined begin with rupture of asperities that are not necessarily larger and are sometimes smaller than the asperities that fail during smaller events the observations are consistent with a model of faulting in which the largest asperities are located at random on the eventual fault plane and fail when the rupture front propagating from the hypocenter reaches them this allows the largest asperities to occasionally be at the hypocenter and to fail immediately but for a large fault it is more likely that they will be located elsewhere and fail later

conditions for lateral downslope unsaturated flow and effects of slope angle on soil moisture movement summary the necessary conditions for lateral downslope flow in the unsaturated zone in hillslopes have not been clearly identified and the effects of different slope angles on soil moisture movement are rarely studied these questions were investigated through drying processes in a homogeneous and isotropic sloping soil tank in this study three experiments with different slope angles were conducted the results showed that the flow direction in the unsaturated zone gradually rotates counterclockwise from the vertical direction to the lateral downslope direction parallel to the slope surface during the drying phase the lateral downslope flow parallel to the slope surface first appears at the surface 0 5 cm and the bottom of the sandy loam in the tank the lateral downslope flow parallel to the slope surface at the surface is due to the state of drying rather than the no flow upper boundary condition the lateral downslope flow parallel to the slope surface at the bottom of the sandy loam is also caused by the state of drying more importantly the results of this study showed that the rate at which the lateral downslope flow turns to be parallel to the slope surface is affected by the drainage rate in contrast to the lateral downslope flow component parallel to the slope surface the flow component normal to the slope surface is less sensitive to changes in the slope angle the influence of the slope angle on the flow component normal to the slope surface is greatest in the middle layer

transport of stable isotopes of water and sulphate within reclaimed oil sands saline sodic mine overburden summary the reclamation of shale overburden dumps from oil sands mining requires the placement of reclamation covers comprised of salvaged organic and mineral soils the primary issues associated with the long term performance of these covers are their ability to store sufficient water to meet transpiration demands and the potential threat of salt ingress into the cover from the underlying shale the first issue has been addressed in previous studies so the objective of this study was to evaluate controls on salt ingress through observations and modelling of the transport of the stable isotopes of water and salt within reclaimed profiles at the south bison hills overburden dump located north of fort mcmurray alberta the water flow model was based on a dual porosity soil vegetation atmosphere model calibrated to observed field data this model was then used to simulate deuterium and sulphate transport within the soil profiles the optimized transport model for deuterium was used to estimate net percolation rates through the cover soil into the underlying shale this model was then used to assess the controls on sulphate migration including the rate of sulphate generation as a result of ongoing oxidation of the pyritic shale the model results indicate that the average net percolation rate is a function of topographic location ranging from 2 2 10 5 m d at slope locations to 20 8 10 5 m d at plateau locations during the unfrozen days these rates of net percolation should have produced observable patterns of salt flushing from the cover and upper shale however the observed sulphate levels could only be simulated by including a production term related to pyrite oxidation of the shale the simulated oxidation rates ranged from 0 4 to 5 65 mg l d similar to those estimated from previous laboratory and field investigations

the morning glory wave of southern california a pulse like disturbance traveling across the los angeles basin was observed on 12 october 2001 with seismographs of the trinet network this wave had a period of about 1000 s and a propagation speed of about 10 m s much slower than seismic waves the seismograph data were compared with barograph data and a good correlation was found so the wave was determined to be atmospheric in origin it had amplitude of about 1 mbar but it was not known what process could produce such a wave since the initial finding we have inspected all the trinet barograph and seismograph data for a period of two and a half years from january 2000 to august 2002 and found four more similar events each of the events has amplitude between 0 8 and 1 3 mbar a period between 700 and 1400 s and a propagation speed between 5 and 25 m s we conclude that these waves are internal gravity waves trapped in a stable layer formed by a temperature inversion some of these waves have large amplitudes and develop into solitary waves nonlinear internal gravity waves similar to the spectacular morning glory wave observed in australia we call these waves the la morning glory waves the la morning glory wave is probably excited by either stormy weather winds such as the santa ana winds or large teleseismic events the morning glory wave could contribute to the recently reported excitation of the background free oscillations of the earth additionally because of its large amplitude it could have important implications for aviation safety as was suggested earlier for the morning glory waves in australia

snowmelt infiltration to frozen prairie soils the paper summarizes the results of 5 years of study of the interaction between snowmelt infiltration inf snow cover water equivalent swe and soil moisture content at the time of melt p for soils in the brown and dark brown zones of the canadian prairies it is shown that in uncracked soils the depth infiltrating water percolates into the soil during the melt sequence is on the average approximately 30 cm and that p of the frozen layer at the soil surface 0 30 cm is the dominant factor governing the amount of snowmelt infiltration independent of soil texture and vegetative cover empirical expressions in the form of power equations and graphs are presented describing the relationship between the variables because of their simplicity they have direct practical application to a number of water management problems of the region a conceptual model for describing the snowmelt infiltration phenomenon in operational water management schemes is presented it divides the infiltration potential o

tracking water pathways in steep hillslopes by δ18o depth profiles of soil water assessing temporal variations in soil water flow is important especially at the hillslope scale to identify mechanisms of runoff and flood generation and pathways for nutrients and pollutants in soils while surface processes are well considered and parameterized the assessment of subsurface processes at the hillslope scale is still challenging since measurement of hydrological pathways is connected to high efforts in time money and personnel work the latter might not even be possible in alpine environments with harsh winter processes soil water stable isotope profiles may offer a time integrating fingerprint of subsurface water pathways in this study we investigated the suitability of soil water stable isotope d18o depth profiles to identify water flow paths along two transects of steep subalpine hillslopes in the swiss alps we applied a one dimensional advection dispersion model using d18o values of precipitation ranging from 24 7 to 2 9 as input data to simulate the d18o profiles of soil water the variability of d18o values with depth within each soil profile and a comparison of the simulated and measured d18o profiles were used to infer information about subsurface hydrological pathways the temporal pattern of d18o in precipitation was found in several profiles ranging from 14 5 to 4 0 this suggests that vertical percolation plays an important role even at slope angles of up to 46 lateral subsurface flow and or mixing of soil water at lower slope angles might occur in deeper soil layers and at sites near a small stream the difference between several observed and simulated d18o profiles revealed spatially highly variable infiltration patterns during the snowmelt periods the d18o value of snow 17 7 1 9 was absent in several measured d18o profiles but present in the respective simulated d18o profiles this indicated overland flow and or preferential flow through the soil profile during the melt period the applied methods proved to be a fast and promising tool to obtain time integrated information on soil water flow paths at the hillslope scale in steep subalpine slopes

recharge processes during snowmelt an isotopic and hydrometric investigation results from hydrometric and isotopic investigations of unsaturated flow during snowmelt are presented for a hillslope underlain by well sorted sands passage of melt and rainwater through the vadose zone was detected from temporal changes in soil water 2h concentrations obtained from sequential soil cores bypassing flow was indicated during the initial snowmelt phase but was confined to the near surface zone recharge below this zone was via translatory flow as meltwater inputs displaced premelt soil water estimates of premelt water fluxes indicate that up to 19 per cent of the premelt soil water may have been immobile average water particle velocities during snowmelt ranged from 6 2 10 7 to 1 1 10 6 ms 1 suggesting that direct groundwater recharge by meltwater during snowmelt was confined to areas where the premelt water table was within 1 m of the ground surface soil water 2h signatures showed a rapid response to isotopically heavy rain on snow inputs late in the melt in addition spatial variations in soil moisture content at a given depth induced a pronounced lateral component to the predominantly vertical transport of water both factors may complicate isotopic profiles in the vadose zone and should be considered when employing environmental isotopes to infer recharge processes during snowmelt

time dependent inversion study of the slow thrust event in the nankai trough subduction zone southwestern japan we estimate time variation of interplate coupling between the subducting philippine sea and the overriding continental plates along the western part of the nankai trough japan during the period between 1996 and 1999 after subtracting annual components and average annual velocities deviation from steady crustal deformation in the shikoku and kyushu islands is examined around 15 gps stations facing the bungo channel detected the following three stage ground displacements of up to 3 cm in 1997 with a duration of 1 year 1 increased displacement rate associated with the 1996 hyuga nada earthquakes 2 an increasingly rapid anomalous period of deformation from june 1997 to the end of 1997 and 3 a slowdown period and return to normal rates of deformation after the end of 1997 linearized least squares locate the slip area of this slow event near the plate boundary beneath the bungo channel the estimated slip is opposite the motion of the philippine sea plate these results support the hypothesis that the observed anomalous caistal deformation is due to a rebound process of the philippine sea plate time dependent inversion analysis shows the following slip history during the initial period of increased displacement rate a visible slip area is resolved beneath the coastal area of southwestern shikoku in the next stage of accelerated displacements the slip area expanded southwestward to the bungo channel beginning around june 1997 when postseismic slip of the 1996 hyuga nada earthquakes almost ended after this accelerated period the estimated thrust slip ends with time

high resolution profiling of the stable isotopes of water in unsaturated coal waste rock summary characterization of the rate of water migration through unsaturated mine waste rock dumps is an essential element in assessing the chemical loading from these landforms yet our understanding of how water moves into through and out of waste rock is incomplete to further understand the rates and magnitude of percolation through waste rock deep high resolution every 0 1 4 5 m depth profiles of the stable isotopes of water 2h and 18o at two coal waste rock dumps and a natural alluvial deposit down gradient of one of the dumps were collected in the elk valley british columbia canada the profiles were generated using vapor equilibrium techniques applied to continuous core samples collected using dry sonic drilling methods elevated core temperatures up to 80 c were measured during sonic coring the isotopic values of pore waters measured in the core samples were corrected for water loss to the atmosphere attributed to the elevated core temperatures the average isotopic composition of the core samples were compared to water collected from rock drains discharging from the base of the dumps the results indicate that high resolution profiles of 2h and 18o can be measured to depths of 86 m in coal waste rock dumps and based on the seasonal cycles in the isotopic composition of recharging water can be used to characterize the migration of recharge water within these dumps these profiles also suggest that recharge into these dumps occurs from both rain as well as snow melt and may be as high as 400 600 mm yr 60 75 of annual precipitation combined with the relatively low volumetric water contents of these dumps 5 10 the rates of water migration through the dumps are tens of meters each year

a slow seismic event recorded in pasadena a prominent long period wave with a duration of 2000 sec or longer was recorded with a very broadband system in pasadena on june 18 1988 this wave was not observed elsewhere and is considered of local origin the acceleration amplitude is 2 5 10 5 cm sec in the northwest direction with the vertical component less than 10 of the horizontal the horizontal acceleration can be interpreted as due to a tilt of the ground of 2 5 10 8 radians to the northwest a slowly propagating pressure wave with an amplitude of about 15 mbars could be the cause of the tilt however there were no reports suggesting such pressure changes a more likely cause is a slow tectonic event near pasadena the required magnitude of such a slow event is m w 0 2 and 4 for a distance of 0 1 1 and 10 km respectively this event could be part of a tectonic episode associated with the larger earthquakes which occurred in southern california around this time especially the december 3 1988 pasadena earthquake m l 4 9 which occurred six months later within 4 km of the pasadena station

a stable isotope study of recharge processes in the english chalk the 2h and 18o values of water contained in unsaturated chalk have been measured in drillcore profiles taken over a period of 28 months on arable land in cambridgeshire eastern england the isotopic composition of rainfall and lysimeter drainage on the same site has also been monitored over a period of four years the distribution of isotope values in the upper few metres of soil and unsaturated chalk shows that the mechanism of infiltration is not simple piston like downward displacement since the scale of vertical fluctuations is incompatible with estimated annual infiltration and the apparent rates of movement of matrix water derived from thermonuclear tritium studies lysimeter drainage is not isotopically identical to matrix water at the same depth suggesting that different routes to water table are associated with consistently different isotopic content although there is an apparent difference between matrix water beneath arable and permanent grassland these differences appear to cancel out in the composition of bulk recharge beneath these land types the regional aquifer has a uniform isotopic composition similar in value to weighted average rainfall and lysimeter drainage suggesting that the recharge abstraction system has been in isotopic equilibrium for many years despite changes in pumping rates and land use two other chalk sites in southern england have been investigated in less detail but indicate clear difference in infiltration behaviour from that seen in cambridgeshire this seems to be related to a higher matrix conductivity and annual rainfall amount

stress redistribution and slow earthquakes abstract earthquakes are usually assumed to result when the gradual stress buildup in a region eventually exceeds some initial local strength there are observations which suggest that a number of mechanisms must have a significant role in stress redistribution in active earthquake regions the stress build up could be non linear in time there is evidence that this is so in the case of some major earthquakes one mechanism that might explain non linear strain buildup is a slow earthquake this is similar to a normal earthquake except that the rupture and slip velocities are very low so that negligible energy is radiated in the normally observed seismic frequency band the slow earthquakes studied here have been recorded by a network of sacks evertson borehole strainmeters installed along the seismically active pacific coast of honshu japan larger slow events may have slow foreshocks and aftershocks in a manner similar to that for normal earthquakes the aftershocks appear to have lower stress drops than the foreshocks the static field changes associated with the izu oshima earthquake m 7 of january 1978 were sufficiently large that they were clearly recorded by the nearest three strainmeters interpretation of the records indicate that this earthquake was in essence a normal quake followed by a slow event of similar moment this interpretation is corroborated by reports of ground vibration and faulting on the izu peninsula

review on soil water isotope based groundwater recharge estimations groundwater recharge estimations are necessary for sustainable management of groundwater resources among various hydraulic hydrogeological and hydrological approaches tracer methods are proposed to improve groundwater recharge estimations soil water isotope based estimates of groundwater recharge rates were developed in the 1960s and have been applied in more than 40 studies reviewed within this manuscript this comprehensive review research distinguishes three fundamental research approaches 1 labelling method with tritium or deuterium which can be used to trace unsaturated zone water movement 2 tracing soil water movement using a seasonal signal of stable isotopes in precipitation mainly applied in humid zones and 3 interpretation of an evaporation signal that impacts soil water stable isotope composition mainly applicable in arid and semiarid regions more recently advances in soil water extraction and analytical methods allow a higher sampling resolution and in situ measurements of soil water stable isotopes analytical advances may strengthen and improve the applicability of stable isotope methods for quantitative recharge we present compare and discuss studies of unsaturated zone isotope profiles with an emphasis on necessary prerequisites such as a substantial thick porous sedimentary layer or negative influences through high clay and silt contents or dry soil conditions copyright 2015 john wiley sons ltd