geomorphic and hydrologic aspects of monsoon floods on the narmada and tapi rivers in central india abstract high magnitude floods during the monsoon season are considered to be india s recurring and leading natural disaster such large flood are extremely important events not only in terms of human impact but also from the standpoint of geomorphic effectiveness and geomorphic work the narmada and tapi rivers in central india are characterized by one of the most intense flood regimes in the seasonal tropics modern historical and palaeoflood records indicate that large floods are relatively common hydrologic and geomorphic events on the narmada and tapi rivers a catastrophic flood on tapi in july 1991 that occurred from heavy rains and a dam break represents one of the highest unit discharges yet recorded in any part of central india flood competence studies indicate that the flood power of the two rivers is comparable with some of the largest historic and prehistoric floods reported from other parts of the world the rivers have preserved geomorphic and sedimentologic records of palaeofloods for the last two millennium and in choral river a 5000 year old record has been located examination of the synoptic conditions associated with the flood generating low pressure systems reveals that all but a few of them are the result of bay of bengal depressions the flooding in such large rivers profoundly challenges flood hazard management because of limited instrumental records and large spatio temporal variation it is therefore imperative that the design engineering community in india incorporates the geomorphic sedimentologic and botanic information in the planning and design of water resource development projects

gradational thresholds and landform singularity significance for quaternary studies abstract geomorphic threshold conditions have been identifed at which stream patterns change and gully initiation occurs for both the threshold conditions are defined by the parameter of relative shear stress which is a measure of the energy state of the system and is based on known values of stream slope and mean annual discharge for patterns or drainage area for gullies the probability of passing from a stream pattern to another or from stable to gullied valley floors is a smooth function of relative shear stress and so the thresholds separating the different states of the geomorphic systems are gradational the singularity of landforms prevents the identification of a sharp threshold and as a result landform sensitivity will differ within the same area and under the same conditions therefore geomorphic predictions and postdictions will be uncertain and quaternary correlations will lack precision

using ambient noise to characterise seismic slope response the case of qiaozhuang peri urban hillslopes sichuan china abstract the mw 7 9 wenchuan earthquake of may 12th 2008 shattered and induced failures on hillslopes surrounding the centre of the town of qiaozhuang located 250 km ne of the mainshock epicentre this motivated investigations on the possible occurrence of site amplification phenomena the initial efforts involved a temporary accelerometer monitoring carried out between april and october 2009 on weigan hill and mount dong located sw and ne of the qiaozhuang centre respectively the monitoring results revealed that the local geological setting characterised by silurian phyllites with sub vertical schistosity at weigan and by fractured precambrian limestones at dong exert major influence on the slopes resonance phenomena with a secondary contribution due to the topographic setting to extend the investigation on local slope response a series of ambient noise recordings were conducted at several sites of the two hills as well as at mount shizi located nw of the town centre which is topographically and geologically similar to mount dong the focus was on the sites monitored by accelerometer stations whose seismic records provided the opportunity to validate the outcomes of ambient noise analysis noise data were analysed using two approaches the standard nakamura s method and a new technique based on analysis of instantaneous polarization properties aimed at estimating ellipticity of rayleigh waves data interpretation was hampered by a contingent factor i e environmental conditions characterised by a strong persistent e w polarized noise at low frequencies below 1 hz and by the complex of geologic and geomorphic conditions the latter particularly in the case of weigan hill appear responsible for a considerable amplification of vertical ground motions the repeated recordings and the comparison of the outcomes of the two techniques of noise analysis with the accelerometer data showed that the new technique provides more stable and consistent results furthermore the new technique was able to reveal site resonance properties that nakamura s method fails to recognise because of transient overlapping of different type waves overall the ambient noise analysis provided evidence of i low frequency resonance 1 hz acting at the scale of the entire relief on weigan hill ii directional amplifications at intermediate frequencies 4 hz affecting ridge crests made of fractured limestone on mounts dong and shizi and iii higher frequency resonances 7 20 hz which vary at a very local scale this information is relevant for inferring the susceptibility of local slopes to earthquake induced failures and hence for the collateral seismic hazard assessment in the qiaozhuan peri urban areas

assessing the reliability of the modified three component spatial autocorrelation technique summary analysis of seismic ambient vibrations is becoming a widespread approach to estimate subsurface shear wave velocity profiles however the common restriction to vertical component wavefield data does not allow investigations of love wave dispersion and the partitioning between rayleigh and love waves in this study we extend the modified spatial autocorrelation technique mspac to three component analysis 3c mspac by determination of love wave dispersion curves this technique provides additional information for the determination of shear wave velocity depth profiles furthermore the relative fraction of rayleigh waves in the total portion of surface waves on the horizontal components is estimated tests of the 3c mspac method are presented using synthetic ambient vibration waveform data different types of surface waves are simulated as well as different modes in addition different spatial distributions of sources are used we obtain rayleigh and love wave dispersion curves for broad frequency bands in agreement with the models used for waveform simulation the same applies for the relative fraction of rayleigh waves dispersion curves are observed at lower frequencies for love waves than for rayleigh waves while 3c mspac has clear advantages for determination of love waves velocities 3c mspac and conventional vertical frequency wavenumber analysis complement each other in estimating the rayleigh wave dispersion characteristics inversions of the dispersion curves for the shear wave velocity depth profile show that the use of love wave velocities confirms the results derived from rayleigh wave velocities in the presence of higher mode surface waves love waves even can improve results application of 3c mspac to ambient vibration data recorded during field measurements pulheim germany show dominance of love waves in the wavefield existing shear wave profiles for this site are consistent with models obtained from inversion of rayleigh and love wave dispersion curves

estimating bedrock depth in the case of regolith sites using ambient noise analysis abstract subsurface geometry particularly the depth of bedrock is crucial in seismic hazard studies because the basin geometry has been shown to play an important role in the altering of seismic waves estimating the bedrock surface using ambient seismic noise analysis has been undertaken by many researchers with most studies focusing on sites with a strong impedance contrast between the bedrock and the overlying materials the application of this technique at regolith sites which is subjected to impedance contrasts in the low to high range is underdeveloped and requires further attention this study seeks to address this need and is focused on the city of adelaide in south australia which exhibits site amplification and is associated with various impedance contrasts analyses of ambient noise data are carried out using the generic function gf of the classic horizontal vertical spectral ratio hvsr method and the spatial autocorrelation spac technique to estimate the depth to bedrock comparison of the bedrock depth predictions from the seismic methods with boreholes drilled in close proximity to the measured sites demonstrate that the spac method provides superior estimates especially to those obtained from the other approach this work demonstrates that the microtremor spac method is an effective tool for estimating bedrock structure at regolith sites

channel form and processes of the flood dominated narmada river india the 1300 km long narmada river flows along a structural lineament alternating between constricting rocky gorges and rapids and meandering wide alluvial reaches channel forms and processes were studied in a 120 km long section of an alluvial reach channel size shape and bedforms in the narmada river are related to very large floods which have occurred three times in this century during such floods the entire 400 m wide channel is utilized and 10 15 m high cliffs on both sides operate as riverbanks normally even the high flows of the south westem monsoon are insufficient to fill the whole channel and hence their effects are limited to building of discontinuous floodplains between the cliffs and modifying bedforms and bars a channel in channel topography is thus created the very large floods are also responsible for erosion of the rocky stretches and building of point bars the river meanders but its movement is restricted because of 1 rocky gorges and scablands operating as anchor points at intervals and 2 the presence of high alluvial cliffs which are topped on extremely rare occasions in spite of being located in a tectonically active zone in a monsoon setting it is the exceptional high magnitude floods at irregular intervals which control the form and behaviour of the narmada river

hvnsr survey in historical downtown l aquila central italy site resonance properties vs subsoil model abstract this paper presents and discusses the results of a detailed seismic noise survey carried out in historical downtown l aquila after the earthquake of 6 apr 2009 m w 6 3 seismic noise data were interpreted through numerical simulations with the support of a subsoil model characterised by four main units from the top to the bottom i soft soils anthropogenic filling material and terra rossa ii l aquila breccia iii l aquila pelite and sand and iv the meso cenozoic carbonate bedrock the hvnsr analysis permitted the identification of two peaks f0 and f1 nearly everywhere f0 0 4 0 7 hz is due to the superposition of l aquila pelite and sand on the carbonate bedrock at 200 300 m below ground level f1 3 15 hz is caused by shallower impedance contrasts due to 3 20 m thick soft sediments overlying l aquila breccia and by the weathering profile of l aquila breccia a numerical simulation was carried out for three different models characterised by i lithology lateral variation in the first 100 m of thickness due to the substitution from north to south of l aquila breccia with l aquila pelite and sand ii the thickness variation of soft top soil onto l aquila breccia and iii the presence of a weathered layer in the upper part of the l aquila breccia the numerical simulation results fit the experimental seismic noise data a spatial correlation between areal distributions of severe damages with that of f1 resonance frequency is found so it follows that the severe damage during the l aquila earthquake of 6 apr 2009 could have been caused by the seismic local effect of the soft top soil and the weathering profile of l aquila breccia

mapping the palaeo piniada valley central greece based on systematic microtremor analyses the application of seismic noise based techniques has become particularly popular in the last decades as they are not invasive and do not require large teams or expensive equipments the horizontal to vertical spectral ratio hvsr is commonly used not only in seismic microzoning studies as far as from noise recording constraining the fundamental resonant frequency but it is also possible to infer the depth of the bedrock knowing the average shear wave velocity of the overlying sedimentary cover or viceversa i e resonance equation for the purposes of the present research more than 300 single station noise measurements were carried out across the piniada valley central greece along and between several transects planned roughly perpendicular to the mean valley trend to understand the palaeogeographic and tectonic evolution of this area we needed an estimation of the geometry at depth of the bedrock underlying the fluvial deposits of the present day pinios river as a result for each measured site we calculated the depth of the bedrock and afterwards such values were opportunely interpolated for obtaining a 3d model of the palaeo piniada valley documenting for the first time the recent late quaternary inversion of the topographic gradient

anabranching rivers their cause character and classification anabranching rivers consist of multiple channels separated by vegetated semi permanent alluvial islands excised from existing floodplain or formed by within channel or deltaic accretion these rivers occupy a wide range of environments from low to high energy however their existence has never been adequately explained they occur concurrently with other types of channel pattern although specific requirements include a flood dominated flow regime and banks that are resistant to erosion with some systems characterized by mechanisms to block or constrict channels thereby triggering avulsion the fundamental advantage of an anabranching river is that by constructing a semi permanent system of multiple channels it can concentrate stream flow and maximize bed sediment transport work per unit area of the bed under conditions where there is little or no opportunity to increase gradient on the basis of stream energy sediment size and morphological characteristics six types of anabranching river are recognized types 1 3 are lower energy and types 4 6 are higher energy systems type 1 are cohesive sediment rivers commonly termed anastomosing with low w d ratio channels that exhibit little or no lateral migration they are divisible into three subtypes based on vegetative and sedimentary environment type 2 are sand dominated island forming rivers and type 3 are mixed load laterally active meandering rivers type 4 are sand dominated ridge forming rivers characterized by long parallel channel dividing ridges type 5 are gravel dominated laterally active systems that interface between meandering and braiding in mountainous regions type 6 are gravel dominated stable systems that occur as non migrating channels in small relatively steep basins anabranching rivers represent a relatively uncommon but widespread and distinctive group that because of particular sedimentary energy gradient and other hydraulic conditions operate most effectively as a system of multiple channels separated by vegetated floodplain islands or alluvial ridges

investigation of composite compacted ground using microtremors abstractthis paper presents an interesting and unique case study of a composite compacted site where the upper section of dynamically compacted material achieved in the first stage of compaction was subsequently removed reinstated and recompacted in lifts in the second stage using conventional roller compaction dynamic compaction was employed initially in this area because of the need to densify deep fill materials although a number of mechanical methods are already available for assessing deep compaction it has been particularly rare to find a cost effective method that can be applied to a deep and extensive compacted site noninvasive techniques based on measurement of the horizontal to vertical spectral ratio hvsr of ambient vibrations microtremors are proposed in this paper to assist in a pilot appraisal of this area which occupies a part of a deep and laterally extensive compacted site first the key features of the measured hvsr curves were interpreted to give a preliminary insight into t

formation of inner gorges abstract under certain conditions a distinctive type of landform the inner gorge evolves in drainage basins undergoing persistent base level lowering inner gorges are typical of basins in north coastal california u s a and one such basin was selected for detailed study based on analysis of along channel distribution of rock types streamside land sliding and stored sediment as well as computation of stream power the following set of conditions appears to accompany the formation of an inner gorge 1 inner gorge parent materials are relatively competent homogenous rock types 2 in inner gorge reaches there is an absence of any base level control that would prevent downcutting 3 continued downcutting occurs due to continued base level fall and this fall is most likely induced by tectonic uplift 4 mass slope failures that form steep straight slopes debris slides are the main denudational hillslope process in the inner gorge 5 sufficient stream power is available to transport landslide derived material out of the inner gorge reach such that alluvial sediment does accumulate in the reach over time and 6 the initial condition of the landscape is a low relief erosionally mature land surface into which the inner gorge is cut this initial condition implies that inner gorges develop in tectonically rejuvenated landscapes the processes of denudation on inner gorge slopes acting over a time scale of 105 years result in a style of landform evolution that approximates parallel slope retreat this type of slope retreat maintains the distinct inner gorge morphology during sustained downcutting though the analysis is confined to one basin in northern california so as to provide a detailed framework to understand inner gorge landform inner gorges appear to be commonplace in areas of moderate to high uplift where lithologic and tectonic conditions are appropriate for their formation a global search for this landform yet to be undertaken is needed to confirm whether it indeed occurs where the above conditions are met

new empirical relationship between resonance frequency and thickness of sediment using ambient noise measurements and joint fit inversion of the rayleigh wave dispersion curve for kangra valley nw himalaya india

vs30 estimates using constrained h v measurements abstract most seismic codes adopt the average shear wave velocity as a key parameter in the first 30 m of subsoil v s 30 estimates of v s 30 are therefore required for both large and small scale seismic microzonation we propose a technique to measure the v s 30 based on the horizontal to vertical spectral ratio h v of microtremor recorded at a single station the h v is fitted with a synthetic curve using the independently known thickness of a superficial layer of the subsoil as a constraint the proposed procedure consists of three steps 1 identify the depth of a shallow stratigraphic horizon from independent geotechnical data 2 identify its corresponding h v marker and 3 use it as a constraint to fit the experimental h v curve with the theoretical one the synthetic h v curve is calculated by assuming a stratified one dimensional 1d soil model and a tremor wave field from distant random sources that are composed of rayleigh and love waves this technique has been validated on different geological settings following a triple check procedure 1 the theoretical rayleigh wave phase velocity dispersion curves calculated for the model derived from the h v fit were compared to the experimental curves measured with the 2d extended spatial autocorrelation esac method and the 1d refraction microtremor remi array surveys 2 the v s profiles and 3 the v s 30 estimates obtained by the proposed technique were compared to those obtained by using the latter array techniques finally the inferred stratigraphy was compared to the geological model the proposed technique is not meant to provide accurate v s profiles but has the potential to provide v s 30 estimates that are coherent with those measured through esac and remi and to satisfy law requirements furthermore the h v is found to be capable in detecting deviations from 1d subsoil geometry over the length of a few meters the correctness of which was confirmed by direct drilling

the use of hvsr measurements for investigating buried tectonic structures the mirandola anticline northern italy as a case study the mirandola anticline represents a buried fault propagation fold which has been growing during quaternary due to the seismogenic activity of a blind segment belonging to the broader ferrara arc the last reactivation occurred during the may 2012 emilia sequence in correspondence with this structure the thickness of the marine and continental deposits of the po plain foredeep is particularly reduced in order to better define the shallow geometry of this tectonic structure and hence its recent activity we investigated in a depth range which is intermediate between the surficial morphological observations and seismic profiles information in particular we carried out numerous passive seismic measurements single station microtremor for obtaining the horizontal to vertical spectral ratio the results of a combined analysis of the peak frequency and its amplitude nicely fit the available geological information suggesting that this low cost geophysical technique could be successfully applied in other sectors of wide morphologically flat alluvial plains to investigate blind and completely buried potential seismogenic structures

site effects in port au prince haiti from the analysis of spectral ratio and numerical simulations abstract to provide better insight into seismic ground motion in the port au prince metropolitan area we investigate site effects at 12 seismological stations by analyzing 78 earthquakes with magnitude smaller than 5 that occurred between 2010 and 2013 horizontal to vertical spectral ratio on earthquake recordings and a standard spectral ratio were applied to the seismic data we also propose a simplified lithostratigraphic map and use available geotechnical and geophysical data to construct representative soil columns in the vicinity of each station that allow us to compute numerical transfer functions using 1d simulations at most of the studied sites spectral ratios are characterized by weak motion amplification at frequencies above 5 hz in good agreement with the numerical transfer functions a mismatch between the observed amplifications and simulated response at lower frequencies shows that the considered soil columns could be missing a deeper velocity contrast furthermore strong amplification between 2 and 10 hz linked to local topographic features is found at one station located in the south of the city and substantial amplification below 5 hz is detected near the coastline which we attribute to deep and soft sediments as well as the presence of surface waves we conclude that for most investigated sites in port au prince seismic amplifications due to site effects are highly variable but seem not to be important at high frequencies at some specific locations however they could strongly enhance the low frequency content of the seismic ground shaking although our analysis does not consider nonlinear effects we thus conclude that apart from sites close to the coast sediment induced amplification probably had only a minor impact on the level of strong ground motion and was not the main reason for the high level of damage in port au prince

bedrock channel incision along piccaninny creek australia piccaninny creek in northwestern australia drains approximately 60 km 2 of high relief sandstone and conglomerate terrain the drainage basin lies within the seasonal tropics and is characterized by ephemeral high magnitude flows flood flows of 50 to 100 m 3 s 1 are probably primarily responsible for the spectacular erosional features along the bedrock channel segments of the creek these erosional features occur in two basic forms as parallel longitudinal grooves and as a downstream sequence that begins with shallow linear depressions parallel to flow and ends in a deep narrow inner channel the longitudinal grooves are assumed to result from longitudinal vortices while the erosional sequences which closely resemble von karman vortex streets are interpreted to result from turbulent vortices shed off irregularities of the channel bed the longitudinal grooves and the inner channel sequence alternate with each other and with gravel floored depositional reaches downstream along the channe

unearthing the buried palu koro fault and the pattern of damage caused by the 2018 sulawesi earthquake using hvsr inversion

the evolution of potholes in granite bedrock w spain abstract spectacular bed forms eroded by flood flows are a feature of the bare rock terraces and channels of some rivers cut into granitic rock in the districts of salamanca ca ceres and badajoz w spain the bed forms comprise a range of pothole types which individually represent various stages in the evolution of mature potholes pothole evolution reflects the hydrodynamics of the erosion by high velocity flood flows of bedrock they evolve in time and in concert with the evolution of the landscape initial shallow depressions deepen gradually into cylindrical forms as vertical erosion increases as time passes lateral erosion increases and leads to wider cylindrical forms which evolve into asymmetrical and bulbous forms second order scouring leads to the development of minor decorative potholes tunnels and niche caves in the large mature potholes data on pothole geometry should complement the findings of other geomorphological studies on individual rivers and on regions

the influence of bedrock geology on knickpoint development and channel bed degradation along downcutting streams in south central indiana geologic controls on knickpoint development and the mechanics of channel bed degradation were eluci dated by comparison of downcutting streams in south central indiana developed in lithologically homoge neous carbonate units and layered siliciclastic strata knickpoints formed in a single lithologic unit are stepped each step consists of a knickpoint face and tread the height of each step is equal to and controlled by bed thickness spatially knickpoints in homogeneous terrain are limited to jointed strata that dip 1 upstream or 2 downstream at angles less than the channel gradient knickpoints observed in lithologically layered strata are characterized by a single step in which resistant jointed rocks overlie and protect weaker units total knickpoint relief is influenced by thickness of the weaker strata knickpoints in layered siliciclastic strata are spatially limited to bedrock reaches produced by differential rates of channel incision knickpoint distribution is also influenced by joint

site characterization through combined analysis of seismic and electrical resistivity data at a site of dhanbad jharkhand india we present the seismic site characterization study using joint modelling of horizontal to vertical spectral ratio hvsr and rayleigh wave phase velocity dispersion curves obtained from multi channel simulation with one receiver msor in a part of dhanbad jharkhand india the joint analysis of these two different but complementary datasets puts stronger constraints on the model parameter search space than one dataset and may help us in finding more unique shear wave velocity model the microtremor data from 12 observation points were utilized to iteratively search 1d shear wave velocity profiles in a predefined model search space these 1d shear wave velocity models were interpolated to generate a 2d shear wave velocity profile of the site using the cubic spline method our results show that the high peak amplitude value of hvsr is associated with low peak period values of hvsr at a distance of 60 m from the southern end of the profile which may indicate the presence of the basin edge effect we identified four layers based on significant changes in the shear wave velocities to a depth of 60 m the major impedance contrasts are located at average depths of 13 m 40 m and 55 m respectively these layers from the surface may indicate the presence of soil highly weathered rock mass moderately weathered rock and bedrock respectively the depth of engineering solid bedrock vs 600 m s is found at the depth of 55 m in the south which gradually decreases to a depth of 40 m in the northern end of the profile the shear wave velocity vs 30 for this area varies between 293 and 357 m s which can be classified as d type site for validation and comparison of our results the electrical resistivity tomography ert data were also recorded along the same traverse using wenner and schlumberger configurations our results show a significant amount of correlation between the 2d shear wave velocity and resistivity profiles obtained from joint analysis of tremor and ert data

shear wave velocity model of the santiago de chile basin derived from ambient noise measurements a comparison of proxies for seismic site conditions and amplification summary we determined a high resolution 3 d s wave velocity model for a 26 km 12 km area in the northern part of the basin of santiago de chile to reach this goal we used microtremor recordings at 125 sites for deriving the horizontal to vertical h v spectral ratios that we inverted to retrieve local s wave velocity profiles in the inversion procedure we used additional geological and geophysical constraints and values of the thickness of the sedimentary cover already determined by gravimetric measurements which were found to vary substantially over short distances in the investigated area the resulting model was derived by interpolation with a kriging technique between the single s wave velocity profiles and shows locally good agreement with the few existing velocity profile data but allows the entire area as well as deeper parts of the basin to be represented in greater detail the wealth of available data allowed us to check if any correlation between the s wave velocity in the uppermost 30 m v30s and the slope of topography a new technique recently proposed by wald and allen exists on a local scale we observed that while one lithology might provide a greater scatter in the velocity values for the investigated area almost no correlation between topographic gradient and calculated v30s exists whereas a better link is found between v30s and the local geology finally we compared the v30s distribution with the msk intensities for the 1985 valparaiso event pointing out that high intensities are found where the expected v30s values are low and over a thick sedimentary cover although this evidence cannot be generalized for all possible earthquakes it indicates the influence of site effects modifying the ground motion when earthquakes occur well outside of the santiago basin

microtremor observations of deep sediment resonance in metropolitan memphis tennessee we measured site resonance periods throughout metropolitan memphis tennessee the site resonance was derived from recordings of ambient microtremor and is a direct measurement of seismic ground shaking in the memphis metropolitan area the period t0 in s is predicted by the empirical relation t0 0 39899 7 8922 10 3h 3 0634 10 6h2 350 h 1100 m where h is the thickness in m of the unconsolidated sediments that overly hard paleozoic rocks assuming that a quarter wavelength relationship governs the relationship between resonant period sediment thickness and average shear wave speed we estimate the average shear wave speed of unconsolidated sediments as a function of sediment thicknesses vs 521 15 0 37459h 350 h 1100 m the scatter in the observations and discordance with earlier work suggests that caution is warranted in applying these values of wave speed indiscriminately to sites in the absence of further detailed work

pleistocene cataclysmic flooding along the big lost river east central idaho relationships between cataclysmic flood generated landforms and flood hydraulics were investigated along box canyon an 11 km long bedrock gorge of the lower big lost river geomorphic mapping along box canyon indicates that a cataclysmic flood completely inundated the gorge resulting in large scale erosional and depositional features on the adjacent basalt upland step backwater hydraulic modeling indicates that a discharge of 60 000 m 3 s was required to produce the geologic paleostage evidence maximum stream power per unit area of bed locally attained values of 26 000 w m 2 during the peak ranking the big lost river flood third in terms of power behind the famous missoula and bonneville floods the spatial distribution of unit stream power indicates that bedrock erosion and boulder deposition on the basalt upland adjacent to box canyon were governed primarily by decreasing unit stream power and or fluctuating unit stream power gradients a preliminary depositional threshold for the largest flood boulders defines a lower limit of flood power required to sustain boulder transport along this bedrock fluvial system ultimately hydrodynamic controls on box canyon flood erosion and deposition derive from the irregular volcanic rift topography of the eastern snake river plain outburst floods from a glacial lake in headwater regions during the late pleistocene may have induced the torrential discharges within box canyon

repeatable process for seismic microzonation using 1 d site specific response spectra assessment approaches application to the city of nice france abstract we are testing three different approaches to assess the site effects based on 1d soil column data the first method follows the eurocodes 8 ec8 approach based on the determination of vs30 soil classes the second one is based on an empirical relationship between vs30 and the fundamental resonance frequency of the site f0 with a response spectra amplification function proposed by cadet et al 2013 and the last one is the application of a 1 d equivalent linear simulation then we propose a repeatable methodology to define the zonation and the associated surface response spectrum from individual results this methodology uses a shape recognition algorithm to build homogeneous response spectra zones and the definition of a specific ec8 like response spectrum adjusted to the distribution of the response spectra in each zone this has been applied to downtown nice a city located on the french riviera that faces the highest seismic hazard in the french mainland area the city is built on two different sedimentary valleys that are prone to lithological site effects the ground acceleration around 1 8 hz can be 20 times higher in the valleys than the one recorded on the surrounding jurassic rock outcrop we defined a 3d geotechnical model composed of 9 homogenous soil layers the surface elastic response spectra in pseudo acceleration obtained with the three methods are compared on the whole city the results indicate that the amplification functions methodology proposed by cadet et al 2012b provides results closer to the numerical simulations compared to ec8 in addition in five sites of the french permanent accelerometric network rap resif located in the valley of nice the site to reference response spectra ratio from the numerical simulations and the spectra amplification function proposed by cadet et al 2012b were compared to earthquake recordings data although the spectra amplification functions are closer to the observations both evaluations underestimate the amplification as they could not capture complex site geometry using the repeatable zonation process on the response spectra from the amplification function three different zones are defined the associated specific response spectra are significantly different from the recommended ec8 response spectra

smooth bumps in h v curves over a broad area from single station ambient noise recordings are meaningful and reveal the importance of q in array processing the boumerdes algeria case 1 single station h v curves from ambient noise recordings in boumerdes algeria show smooth bumps around 1 and 3 hz a complementary microtremor study based on two 34 and 134 meter aperture arrays evidences that these bumps are indeed real peaks produced by two strong vs contrasts at 37 and 118 meters depth strongly smoothed by very high s wave attenuation in the two sedimentary layers these two h v bumps observed over a broad area are meaningful and reveal the importance of q in s wave velocity modeling from microtremor array data processing it also appears that tertiary rocks should be at least in some cases taken into account together with the quaternary sediments to explain single station h v frequency peaks and therefore that considering only the first 30 m of soil for vs amplification evaluation as usually recommended sometimes leads to flaky results by artificially eliminating non explained low frequency peaks from the analysis

controls on bedrock channel incision along nahal paran israel nahal paran drains 3600 km2 of egypt s sinai peninsula and israel s negev desert much of the channel is alluvial but a canyon 10 5 km long has been incised into late cretaceous chert and dolomite in the lower portion of the basin slackwater deposits and paleostage indicators preserved within the canyon record approximately 10 floods of 200 to 2500 m3 s 1 over a period of at least 350 years step backwater simulations of flood flow hydraulics indicate extreme variations in stream power per unit area along the length of the canyon and associated variability in energy expenditure and sediment transport these variations reflect channel cross sectional morphology the greatest values of stream power occur along the lower half of the study reach in association with three pronounced knickpoints and an inner channel the locations of these features reflect the exposure of thick resistant chert layers along the channel the presence of several similar but buried and inactive knickpoints along the upper study reach indicates that the locus of most active channel incision has shifted with time probably in response to baselevel changes associated with tectonic activity along the dead sea rift thus the rate and manner of channel incision along the canyon of nahal paran are controlled by lithologic variability and tectonic uplift as they influence channel morphology and gradient which in turn influence hydraulics and sediment transport

site characterization of strong motion recording stations of delhi using joint inversion of phase velocity dispersion and h v curve site characterization is one of the most important aspects of any strong motion instrumentation nowadays it has become common practice to provide the characterization details up to bedrock level without proper site characterization strong motion records of any station cannot be fully utilized in india strong motion instrumentation sites were classified in three categories as per v s 30 values these v s 30 values were estimated using the borcherdt 1994 methodology in which physical properties of visible soil layer are used for v s 30 estimation because this methodology does not use any field testing the probability of getting erroneous results is very high hence to get accurate assessment of site characteristics we conducted field testing at 19 strong motion instrumentation sites in delhi india the site characteristics assessed here are determined using joint inversion of multichannel analysis of surface waves and horizontal to vertical spectral ratio hvsr from ambient noise results simultaneously to estimate shear wave velocity profiles the benefit of using this method is that it provides site characteristics assessed through shear wave velocity profiles up to much deeper soil strata the results obtained from this analysis are further validated using ground response analysis from recorded ground motions further the profiles obtained are studied for uncertainties using the computer program strata transfer functions obtained from strata are then compared with hvsr of ambient vibration records as well as hvsr from weak motion earthquake records available for the sites these curves are found to well matching with each other in this study site characterization carried out here will be very useful for studies related to seismic hazard assessment of the delhi region and studies related to attenuation models

energy time and channel evolution in catastrophically disturbed fluvial systems abstract two diverse fluvial systems show that with time channels adjust such that the rate of energy dissipation is minimized one fluvial system characterized by high relief and coarse grained sediment was subjected to an explosive volcanic eruption the other system characterized by low relief and fine grained sediment was subjected to dredging and straightening study of the expenditure of kinetic and potential energy components of total mechanical energy provide an energy based rationale of the interdependency between processes and forms during channel evolution spatial and temporal trends of aggradation and degradation are similar although relative amounts of aggradation in the high energy system are greatly enhanced by the deposition of large amounts of eroded bank material from upstream reaches degradation accompanied by widening is the most efficient means of energy dissipation because all components of total mechanical energy decrease with time widening dominates energy dissipation in the coarse grained system to offset increases in hydraulic depth caused by incision in the low energy fine grained system channel adjustment and energy dissipation are dominated by vertical processes because of low relative values of kinetic energy and because eroded bank sediment is transported out of the drainage basin and does not aid in downstream aggradation energy dissipation or channel recovery specific energy is shown to decrease nonlinearly with time during channel evolution and provides a measure of reductions in available energy at the channel bed data from two sites show convergence towards a minimum specific energy with time time dependent reductions in specific energy at a point act in concert with minimization of the rate of energy dissipation over a reach during channel evolution as the fluvial systems adjust to a new equilibrium

lithologic control of bedrock meander dimensions in the appalachian valley and ridge province marked differences in bedrock meander dimensions in the appalachian valley and ridge province at times in adjacent reaches of a single stream are related to differences in relative erodability of the bedrock meanders cut in thick bedded to massive lithologies typically carbonates are distinctly smaller overall than meanders cut into shaly lithologies other factors that could affect bedrock meander dimensions were considered and none appeared to offer any help in explaining the dimensional differences observed above in plateau regions underlain by essentially horizontal strata the meander form characteristic of one lithology may become superimposed upon another as incision progresses producing anomalous relationships between bedrock meander dimensions and lithology empirical relations developed from meander geometry measurements and estimated bedrock erodability for 78 bedrock meander reaches containing a total of 1089 individual meander loops show that meanders cut in shaly lithologies ml 105 q0 50f where ml meander length and qf most probable annual flood are about twice the length of meanders cut in non shaly lithologies ml 39 30 56f the valley floor width of the meanders cut in shaly bedrock vf 28 q0 43f is two to three times wider than the valley floor width of the meanders cut in the more resistant non shaly bedrock vf 8 q0 43f the mean and median meander length values for individual reaches typically differ by less than 10 per cent

refraction microtremors data analysis and diagnostics of key hypotheses surface wave methods are quite popular for site characterization in geotechnical earthquake engineering among these techniques a particular role is taken by passive methods for their ability to yield information on the low frequency range and consequently on large depths one such passive method the refraction microtremors remi technique has been proposed as a simple alternative to 2d array techniques to estimate surface wave dispersion by using linear arrays of geophones the technique owes its name to the use of widely available instruments also adopted for seismic refraction the basic hypotheses underlying remi are that noise is distributed isotropically in azimuth or is aligned exactly with the array these conditions often are not met and in most cases they are not verified because such analysis requires an accurate approach to data processing that is rarely applied we have developed an algorithm that verifies remi s basic hypotheses by analyzing experimental data in addition we have propo

bedrock benches and boulder bars floods in the burdekin gorge of australia the burdekin gorge of northeastern australia lies within the seasonal tropics and is characterized by high discharge variability slackwater sediments and paleostage indicators in the gorge record seven large floods that have occurred during the past 1 200 yrs these floods range in magnitude from 11 000 to 30 000 m 3 s 1 and are characterized by large downstream variations in hydraulics the floods generate high values of velocity boundary shear stress and stream power per unit area downstream fluctuations in these variables help to explain the location of boulder bars high flood levees small scale erosional features in the bedrock and the formation of inner channels boulder bars and flood levees form where shear stress and stream power decrease due to channel widening small scale erosional features such as potholes and troughs are best developed at sites of channel constriction and associated increases in shear stress and stream power the development of the inner channel appears to be controlled by complex interactions between bedrock lithology and structure and by flow hydraulics all of the channel features are related to the hydraulics of large floods which therefore are the dominant controls on many aspects of channel morphology in this bedrock gorge

hvsr deep mapping tested down to 1 8 km in po plane valley italy abstract the horizontal to vertical spectral ratio hvsr of seismic noise is extensively used in seismic microzonation for its capability to provide a good approximation to the subsoil main resonance frequencies of geotechnical and seismic engineering interest this implies in turn that it has also an approximate passive subsoil mapping capability independent of the level of noise illumination albeit limited to relatively shallow depths since tilt sensitivity makes hvsr unreliable below 0 1 hz however we have experimentally verified that hvsr subsoil mapping capability extends to depths in the kilometer range by applying it to the largest sedimentary basin of italy the po plain valley there we were able to resolve the major stratigraphic discontinuities down to the sediment bedrock interface for which we estimated a depth of 1 6 km with a 25 uncertainty while the surface mapped from oil exploration indicates a depth of 1 8 km quarter of an hour recordings gave always stable signals that fitted to synthetic curves using as a constraint the parameters of the shallow subsoil provided a stratigraphic map consistent with the independent survey this candidates hvsr as a fast and inexpensive first order subsoil mapping tool down to depths of geological and exploration interest

using advanced insar techniques to monitor landslide deformations induced by tunneling in the northern apennines italy synthetic aperture radar sar interferometry insar is used to make measurements of small surface displacements in different situations including ground settlement landslides and excavations we document the deformation history of four dormant deep seated landslides in the northern apennines of italy that were reactivated by the excavation of a double road tunnel the tunnel is part of a larger infrastructure project that involves the improvement of the a1 highway which connects bologna and florence the excavation of the tunnel under the landslides basal shear surfaces started in 2011 and with the advance of the tunnel front deformation began to occur causing damages to homes and infrastructures the tunnel passes under the small villages of ripoli and santa maria maddalena the deformation slowed down after the tunnel was completed in november 2014 and low surface displacement rates were registered for the period between october 2014 and june 2016 we show the results of an insar analysis designed to measure surface movements between 2003 and 2016 the insar displacements are derived from the envisat cosmo skymed and sentinel 1 datasets and cover the main construction phase of the tunnel 2011 2015 a detailed geological and geomorphological mapping of the slope is developed based on the field evidence and on the spatial pattern of surface deformation provided by our insar analysis together with the map a new conceptual geological model of the slope in tectonically sheared and weathered flysch is presented the satellite insar data show good agreement with available ground based monitoring data that include inclinometer and gps measurements while small differences occur with respect to deformation time series obtained from a ground based insar instrument in particular the insar results for the x band data of cosmo skymed demonstrate the close relationship between the position of the excavation front and the displacement rates of previously dormant landslide deposits conversely the concurrent rainfall does not appear to significantly influence the observed behavior and if any had only a minor influence on the displacement history of the investigated landslides

faster better shear wave velocity to 100 meters depth from refraction microtremor arrays current techniques of estimating shallow shear velocities for assessment of earthquake site response are too costly for use at most construction sites they require large sources to be effective in noisy urban settings or specialized independent recorders laid out in an extensive array this work shows that microtremor noise recordings made on 200 m long lines of seismic refraction equipment can estimate shear velocity with 20 accuracy often to 100 m depths the combination of commonly available equipment simple recording with no source a wavefield transformation data processing technique and an interactive rayleigh wave dispersion modeling tool exploits the most effective aspects of the microtremor spectral analysis of surface wave sasw and multichannel analysis of surface wave masw techniques the slowness frequency wavefield transformation is particularly effective in allowing accurate picking of rayleigh wave phase velocity dispersion curves despite the presence of waves propagating across the linear array at high apparent velocities higher mode rayleigh waves body waves air waves and incoherent noise two locations illustrate the application of this technique in detail coincident with a large accelerometer microtremor array in reno nevada and atop a borehole logged for shear velocity in newhall california refraction equipment could duplicate microtremor results above 3 hz but could not estimate velocities deeper than 100 m refraction microtremor cannot duplicate the detail in the velocity profile yielded by a suspension logger but can match the average velocity of 10 to 20 m depth intervals and suggest structure below the 100 m logged depth of the hole eight additional examples from southern california and new zealand demonstrate that the refraction microtremor technique quickly produces good results from a wide range of hard and soft sites

development of anastomosing channels in south central indiana abstract numerous streams in south central indiana tributary to the ohio river exhibit anastomosed channel patterns the anastomosing patterns are characterized by a primary channel and one or more auxiliary channels anabranches that are often abandoned or receive flow only during flood development of the anastomosed pattern involves avulsion and proceeds in a sequential manner where 1 aggradation significantly reduces channel depth 2 overbank flow occurs more frequently as channel capacity is reduced 3 floodplain deposits are incised by sediment deficient overbank flow producing a new channel gully having a lower gradient and elevation than the primary channel and 4 the gully created by overbank flow extends upstream and captures the drainage system converting the previous trunk channel into an anabranch avulsion is typically associated with aggrading fluvial systems but the investigated streams are undergoing an episode of degradation avulsion occurs because of localized deposition along concave up channel segments the concave up channel reaches are spatially controlled by the occurrence of non resistant strata that separate beds of resistant sandstone thus the location of avulsion and anastomosing channels is predetermined by the lithology and stratigraphy of the underlying bedrock

vertical seismic profiling of oroville microearthquakes velocity spectra and particle motion as a function of depth direct evidence of site distortion of p and s wave microearthquake source spectra at oroville california is presented the data were gathered by placing vertical and three component seismometers at 90 m intervals in a 500 m borehole through the cleveland hill normal fault on which the 1975 ml 5 7 oroville earthquake took place high pressure hydraulic locking mechanisms were used to firmly lock the seismometer packages against the borehole wall digital event triggering geos recorders were used to receive the data some 30 seismic events including 12 microearthquakes were recorded during the 4 months the seismometers were deployed by comparing the velocity spectra of microearthquake waves at the different depths it can be seen that scattering and attenuation in the shallow crust around the borehole dominantly affect high frequency s waves above 15 hz the value of the apparent s wave quality factor qas for the upper 500 m of crust at this site is 9 one feature of this low qas is a gross difference between s wave corner frequencies observed at ground level and 500 m downhole for example the uphole and downhole s wave corner frequencies for the mcoda 0 4 microearthquake of julian day 259 differ by a factor of 2 or more low quality factors and depth dependent corner frequencies were also observed for p waves but these data are less definitive due to lower signal to noise ratios based on their three component particle motions and polarizations the direct s waves of the microearthquakes appear to be composed of two phases which have similar amplitudes but different apparent velocities it is possible that the velocity differences are a result of anisotropy in the underlying rock

response of alluvial rivers to slow active tectonic movement alluvial rivers respond to valley slope deformation caused by active tectonics in various ways depending on the rate and amount of surficial deformation and on the type of river on the basis of experimental results and field examples hypothetical models of river response to anticlinal uplift and synclinal subsidence were developed for different types of alluvial rivers an experimental braided channel responded to anticlinal uplift across the channel with degradation and terrace formation in the central part of the uplift with subsidence aggradation in the central reach was the main response transverse bars developed downstream of the subsidence axis an experimental meandering channel responded to slope steepening with a sinuosity increase bank erosion and point bar growth occurred downstream of the anticlinal axis and upstream of the synclinal axis upstream of the uplift axis and downstream of the subsidence axis where the slope was flattened water flooded over bars local convexity in longitudinal profiles of the middle rio grande new mexico is considered to be formed by a domal uplift local aggradation and degradation could be explained by the effect of uplift the san joaquin river california which is now highly controlled does not show clear adjustment to the rapid subsidence due to ground water withdrawal it shows however a channel pattern adjustment to active tectonic subsidence that has been occurring for a long time the san antonio and guadalupe rivers in texas both increase their sinuosity significantly where monoclinal movements steepen valley slopes

extracting coherent wave fronts from acoustic ambient noise in the ocean a method to obtain coherent acoustic wave fronts by measuring the space time correlation function of ocean noise between two hydrophones is experimentally demonstrated though the sources of ocean noise are uncorrelated the time averaged noise correlation function exhibits deterministic waveguide arrival structure embedded in the time domain green s function a theoretical approach is derived for both volume and surface noise sources shipping noise is also investigated and simulated results are presented in deep or shallow water configurations the data of opportunity used to demonstrate the extraction of wave fronts from ocean noise were taken from the synchronized vertical receive arrays used in the frame of the north pacific laboratory npal during time intervals when no source was transmitting

influence of the vs profiles beyond 30 m depth on linear site effects assessment from the kik net data site effects may be assessed using a standard soil classification parameter vs30 the harmonic average shear wave velocity in the first 30 m however this index does not account for the complexity of the velocity profile especially its variability at depth in the present study in addition to vs30 we propose consideration of the gradient of the vs profile from 0 to 30 m depth denoted b30 a lower gradient value means low velocity increases with depth a higher gradient indicates a rapid velocity increase with depth in the shallow layers in addition we consider the fundamental resonance frequency of the soil f0 which has been shown to be a relevant parameter for site effect assessment and which is obtained from the empirical site response using the japanese kik net database we analyze the variability of the vs profiles and the empirical borehole site responses of selected sites through the vs30 the velocity gradient b30 and f0 we select 289 sites for which the 1d linear numerical modeling is close to the empirical site response and a vs at the downhole station is greater than 1000 m s for a given vs30 class b30 and f0 can be used to distinguish between two types of sites deep sedimentary sites and sites with high velocity contrast at shallow depths we find that even if the gradient is calculated using shallow information its use improves the site amplification characterization compared to using only vs30 by reducing the intersite site response variability as expected however this improvement is limited for deep sedimentary sites on the other hand f0 is able to reduce the intersite response variability for deep sedimentary sites even though it is limited to specific vs30 classes thus the combined use of vs30 b30 and f0 improves the assessment of linear site amplification

seismic scattering attenuation estimates for the german ktb area derived from well log statistics we applied a recently developed scattering attenuation theory to model q values measured at the german ktb site and found that scattering attenuation plays an important role in the upper crust in this area this does not conform with previous studies that suggest absorption mechanisms as the main reason for the attenuation the scattering attenuation model used is based on the wave propagation theory in random media and allows quantification of scattering attenuation in complex geological regions using simple statistical estimates from well log data for our estimates of scattering q we used statistical models of heterogeneities obtained from ktb logs a good agreement between the magnitude of scattering attenuation and the measured q values shows the necessity of evaluating the role of scattering in seismic attenuation phenomena

alluvial river response to neotectonic deformation in louisiana and mississippi repeat geodetic surveys show uplift of the monroe and wiggins anticlines in louisiana and mississippi there are deformed quaternary terraces which indicate long term deformation in the valleys of the alluvial rivers that cross these structures and there are floodplain and channel convexities that provide evidence of modern deformation in addition the channels show significant variations of morphology sinuosity gradient and depth and behavior appropriate to reaches of increased and decreased valley slope these alluvial rivers are adjusting to modern deformation and their adjustment confirms two geodetic leveling anomalies

multi channel patterns of bedrock rivers an example from the central narmada basin india abstract an anomalous multiple channel pattern in bedrock is observed on a predominantly downcutting reach of the narmada river the multi channel reach 800 2750 m in width and 8500 m in length is bounded by major faults and is underlain by granite and gneiss bedrock geomorphological investigations reveal differences among the upstream middle and downstream sub reaches of the multi channel study area whereas the upstream sub reach is dominated by deep flows and fine sediments the lower sub reach is characterized by a steep gradient and rapids the middle sub reach is the widest and is marked by thickly forested islands and boulder berms the characteristics of the three different sub reaches suggest control by the interactions of lithology flood processes and tectonics estimations of hack s 1973 stream gradient index values indicate considerable variations for the sl values along the length of narmada river the highest value of gradient index sl 797 is associated with the multi channel reach implying lithologic or tectonic control given the dimensions of the reach and its channels it appears that the present hydrological regime is inadequate to produce the feature we hypothesize that the multi channel pattern development in bedrock was initiated by block or domal uplift enhanced gradients and extreme floods permitted the system to exploit linear weaknesses in the bedrock leading to the development of anabranches and establishment of multiple channels in bedrock abrupt changes in the channel planform and morphology at the study site indicate that the river is adjusting its channel geometry width depth gradient and plan configuration to a new equilibrium channel morphology through the action of the extreme floods characteristic of this fluvial environment

separation of high and low level ambient noise for hvsr application in city conditions for greater toronto area abstract the nakamura method which involves horizontal to vertical spectral ratio hvsr analysis is widely used for seismic microzonation studies the noise from local traffic in city conditions presents a challenge for the application of hvsr analysis this article presents a technique developed for separation of the transient noise due to local traffic high level noise and background ambient noise low level noise and the application of the hvsr analysis to both partitions of the noise this approach is applied to identify the predominant frequencies for almost 200 noise samples from the greater toronto area the results demonstrated that the developed technique is effective and allows estimation of the fundamental resonant frequency in the hvsr in urban environment even in the presence of intensive nearby traffic the interpretation of the obtained results showed that most probably the lower fundamental frequency appears due to multiple reflections from the overburden bedrock boundary in some cases a resonance with higher amplitude is dominant and it is due to a contrast boundary between soil layers in the overburden

patterns of alluvial rivers the pattern planform of a river can be considered at vastly different scales depending upon both the size of the river and the part of the fluvial system that is under consideration figure 1 for example in the broadest sense river patterns comprise a drainage network dendritic parallel trellis etc figure la the type of pattern is of interest to geomorphologists and geologists who interpret geologic conditions from aerial photographs at another scale a river reach which in figure lb is meandering is of interest to the geomorphologist who is interested in what that pattern reveals about river history and behavior and to the engineer who is charged with maintaining navigation and preventing major instability when a single meander is examined figure 1 c the hydraulics offtow the sediment transport and the potential for bank erosion are of concern in addition the sedimentologist is interested in the distribution of sediment within the bend bed forms within the channel figure ld and sedimentary structures figure ie which also establish a component of roughness for the hydraulic engineer finally the individual grains figure if provide geologic information on the sediment sources the nature of sediment loads and the feasibility of dredging for gravel there is an interaction of hydrology hydraulics geology and geomorphology at all scales which emphasizes the point that the fluvial system as a whole cannot be ignored even though only a component of the system is to be studied in this review only the patterns or planforms of alluvial rivers are discussed although it is apparent that the hydrologic and sediment yield characteristics of the drainage basin figure la as well as its geologic history cannot be ignored in the explanation of the pattern of any river

site effect evaluation using spectral ratios with only one station the spectral ratio technique is a common useful way to estimate empirical transfer function to evaluate site effects in regions of moderate to high seismicity the purpose of this paper is to show that it is possible to estimate empirical transfer function using spectral ratios between horizontal and vertical components of motion without a reference station the technique originally proposed by nakamura to analyze rayleigh waves in the microtremor records is presented briefly and it is discussed why it may be applicable to study the intense s wave part in earthquake records results are presented for three different cities in mexico oaxaca oax acapulco gro and mexico city these cities are very different by their geological and tectonic contexts and also by the very different epicentral distances to the main seismogenic zones affecting each city each time we compare the results of nakamura s technique with standard spectral ratios in all three cases the results are very encouraging we conclude that if site effects are caused by simple geology a first estimate of dominant period and local amplification level can be obtained using records of only one station

mapping geomorphology a journey from paper maps through computer mapping to gis and virtual reality abstract maps are integral components of research in geomorphology and quaternary geology visual presentation of the spatial and temporal distribution of a phenomenon often provides clues to the process es that generated the phenomenon compiling information on maps interpreting spatial patterns and using standard topographic maps were fundamental parts of the undergraduate experience why have such experiences been slowly disappearing from undergraduate curricula how are geology majors taught map scale map projections and the pitfalls associated with the display of spatial information neglect in preserving the mapping tradition places the geology major at a disadvantage the use of maps and mapping is undergoing a renaissance use in the classroom has a bright future because of digital scanning computer cartography geographic information systems gis and virtual reality pen and ink techniques should be relegated to museums pencil sketches can be scanned and perfect products generated every time these techniques however do not eliminate the need for basic map knowledge such as scale projections and generalization what assumptions about map projections have been built into the software how are spatial data and attribute data integrated into the resultant map in a geographic information system gis because the application of virtual reality to geomorphic processes looms on the horizon geologists must recognize how the current spatial revolution can help with the assessment of geologic phenomena and teach students to function with the new technology

adjustments by the charwell river new zealand to uplift and climatic changes major climatic changes and rapid local and regional tectonic movements were common in new zealand during the late quaternary and caused a diversity of adjustments in the drainage basin and piedmont reaches of the charwell river which are separated by the hope fault the onset of semi arid frigid climates during the latest pleistocene probably greatly increased hillslope sediment yields in a periglacial environment and the piedmont reach aggraded as much as 42 m on top of a broad strath with the return of humid mesic climates in the holocene sediment yields decreased as dense forests again mantled the slopes and the piedmont reach degraded as mush as 81 m dating of eleven cut and strath terraces by radiocarbon calibrated weathering rind measurements on greyawake cobbles shows the degradation rates varied greatly during the last 14 ka 1 ka 1000 yr initial degradation rates of 4 m ka 1 increased to 30 m ka 1 by 6 ka ago during a mid holocene climatic optimum since 4 ka ago degradation rates have been only 1 2 m ka 1 comparable to uplift rates in the piedmont reach inferred from marine terrace studies and the river is again cutting a broad strath each broad strath represents equilibrium conditions attained by this powerful stream during interglacial times despite episodes of being overwhelmed by climatically induced sediment yield increases during full glacial climates and having to maintain a long term degradation rate equal to the uplift rate the 75 81 m of degradation since formation of the latest pleistocene fill terrace tread is the sum of the amount of late pleistocene valley floor aggradation and the amount of regional uplift that occurred between the estimated times of major strath formation at about 30 and 0 ka the 39 m of tectonically induced degradation below the pre aggradation strath is sufficiently large that post 30 ka uplift may have doubled holocene degradation rates each of the eleven degradation terraces represents pauses of a few centuries in holocene downcutting brief equilibrium conditions were attained by streambed armoring and concurrent growth of riparian plants both processes progressively increased hydraulic roughness and the shear stresses needed to entrain streambed materials occasional floods possibly from rare cyclones derived from tropical moisture sources destroyed streambed armor and channel downcutting was renewed thus the formation of eleven equilibrium terraces can be accounted for without postulating additional tectonic perturbations or secular climatic changes

flood geomorphology of the katherine gorge northern territory australia the katherine gorge is a narrow deep canyon system developed in resistant sandstone the tropical monsoonal climate results in rare flood events of very large magnitude these floods flush sand sized sediment as washload through the gorge but local accumulations are preserved as slack water deposits at tributary mouths paleoflood hydrologic analysis of the deposits employing step backwater flow modeling allows quantitative estimates to be made of geomorphically significant flows for an annual exceedence probability of 10 2 the gorge may experience discharges of 6 000 m 3 s mean velocities of 7 5 m s flow depths of 15 to 45 m stream powers per unit area as great as 1 10 4 watts m 2 and bed shear stresses of 1 5 10 3 n m 2 such flows are required to transport boulders 3 m or more in intermediate diameter that occur at large scale riffles at maximum stage pools reach depths of 45 m and are preferentially developed at vertical joint intersections in the rock probably through intense hydraulic action pool and riffle development thus reflects the channel boundary characteristics for extreme flow conditions additional indicators of especially intense flow phenomena include potholes flutes abraded facets on rock bar surfaces and scabland development on upland bedrock surfaces

channel form and processes in bedrock and alluvial reaches of the raritan river new jersey fluvial geomorphologists have generally considered alluvial and bedrock channels to be fundamentally different in character alluvial channels being shaped by sediment transport processes and bedrock channels being shaped by structural and lithologic controls this study examines a 12 km bedrock floored reach of the raritan river that separates two gravel bed reaches above and below the bedrock channel has a patchy veneer of sandy gravel that covers the bed in areas of low slope but elsewhere consists of lateral bars and discrete two dimensional gravel bed forms perched on bedrock mean b axes of the 25 largest clasts on the crests of these bed forms range from 10 4 to 13 8 cm shear stresses estimated from measured velocity profiles and depth slope calculations indicate that most clasts on the bed forms are entrained by the bankfull discharge 290 m s which is equaled or exceeded about 1 of the time the thalweg of the 80 m wide channel is incised about 0 5 to 0 7 m and it meanders with a wavelength of about 750 m or approximately 10 times channel width this thalweg meander wavelength is consistent with reference to drainage area when compared to channel meander wavelengths in other locations within the basin and is similar to that in other rivers of comparable dimensions and discharge the bedrock alluvial reach is similar to alluvial channels with reference to meander geometry and sediment distribution it occupies an intermediate position on a continuum of channels of varying sediment supply in relation to transport capacity ranging from alluvial channels to those completely formed in bedrock

hvsr passive seismic stratigraphy for the investigation of planetary volcanic analogues abstract this paper presents new results of the application of passive seismic surveys for the stratigraphic investigation of planetary volcanic analogues we tested hvsr horizontal to vertical spectral ratio surveys that seem particularly suitable for planetary subsurface exploration in order to exploit the potential of these surveys in stratigraphic applications hvsr surveys were undertaken at the tinguaton volcanic region lanzarote canary islands seismic noise measurements were collected during the pangaea x 2018 testing campaign which formed part of the european space agency s esa astronaut training program single station free field seismic noise data were collected along two orthogonal profiles one crossing the tinguaton volcano the other passing alongside the tinguaton caldera seismic stratigraphic sections obtained from the shear wave velocity constrained inversion of the main h v peaks provided the main impedance contrasts between layers and a bulk estimate of the shear wave velocity in the layers contour maps of the hvsr patterns were used to recognize and identify the main volcanic units such as scoria deposits and different basaltic lava flows geological structures such as a regional fault related to the volcanic vent source and morphological characteristics such as the tinguaton caldera this study also identified several pitfalls that may limit the accuracy of such investigations these include the multilayer setting of scoria deposits and partly of underlying basalts as well as the presence of very thin horizons or a very gradual increase in shear wave velocity our study also shows the topographic effect due to the volcano s sharp topography along crater rim is significant and results in severe artifacts in the data from our work it is clear that hvsr method is an effective method to support the investigation of planetary volcanic terrains on the moon and mars with similarly volcanic complex geological settings even where horizontal layering and the isotropic site response are not fully verified

equivalent linear site response analysis on the site of the historical trakoscan castle croatia using hvsr method this paper presents a major extension of seismic vulnerability research project on the site of trakoscan castle based on the initial horizontal to vertical spectral ratio hvsr results from stanko et al 2016 the estimated hvsr site frequencies and hv amplification at trakoscan castle can only be used as an indication of the initial soil site frequency and amplification so called natural soil model corresponding to the subsoil profile without the influence of an earthquake the equivalent linear eql site response analysis has been carried out for different earthquake scenarios for a maximum input rock peak ground acceleration pgarock that corresponds to return periods of 95 0 08 g 475 0 18 g and 1000 years 0 31 g the aim of the research is to evaluate structural seismic design responses and to determine type and degree of damage caused by local site effect which is the result of an alluvial basin and topographic influences the main objective of this research is the formation of local microseismic zones based on an eql analysis surface spectral acceleration and amplification maps at the predominant frequency based on the hvsr frequency response of the core structure of trakoscan castle and the tower itself fundamental and higher frequency modes maps of surface spectral acceleration and soil amplification at different frequencies 3 5 and 10 hz are developed for different input pgarock levels 0 08 0 18 and 0 31 g to evaluate seismic response of the castle observed amplifications are correlated with ground motion polarization and directionality of the ground motion from the alluvial basin to the hilltop shortening of predominant frequencies lengthening of the period particularly in the alluvial basin has been observed with higher input pgarock in the eql analysis this effect is not manifested in the trakoscan hill and predominant frequencies match hvsr frequencies the use of certain geophysical survey methods at historical sites is a big problem because terrain features e g steep hills mountains ridges slopes cliffs create lack of space and make it impossible to carry out geophysical investigation microtremor measurements at historical sites can overcome this limitation and provide local seismic response and vulnerability behaviour of historical monuments without destroying their authenticity also computational modelling can greatly improve the results the eql site response analysis on the site of trakoscan castle has confirmed and improved the results of seismic response and vulnerability based on hvsr method

s wave velocity profiling by joint inversion of microtremor dispersion curve and horizontal to vertical h v spectrum a joint inverse analysis using both microtremor dispersion curve and horizontal to vertical h v spectrum is proposed for estimating the s wave velocity vs profiles of subsurface soils in the inversion both microtremor dispersion and h v data are assumed to be the rayleigh wave dispersion curve and the surface both rayleigh and love wave h v spectrum that have been theoretically derived by taking into account the effects of their fundamental and higher modes the proposed joint inversion as well as the conventional one using dispersion data alone is per formed at four sites where shallow vs profiles down to engineering bedrock are available the vs profiles estimated by the proposed joint inversion are more con sistent with available down hole velocity logs than those by the conventional method in particular the proposed inversion shows significant improvement in estimating bedrock vs structures compared to the conventional inversion sensitivity analyses indicate that the surface wave h v ratio is sensitive to the bedrock vs structure more than the rayleigh wave phase velocity confirming that the proposed joint inversion including h v spectrum is promising

are microtremors useful in site response evaluation we have reviewed the applicability of microtremor measurements to evaluate site response of soft soils to this end we evaluated three different techniques commonly used to estimate site effects from microtremor measurements interpretation of fourier amplitude spectra computation of spectral ratios relative to a firm reference station and finally computation of spectral ratios of horizontal components relative to the vertical component of ground motion nakamura s technique these techniques are applied to microtremor records obtained in three cities in mexico mexico city oaxaca and acapulco these cities differ in their local geological conditions and in their seismotectonic environment in order to evaluate the results obtained from microtremor measurements we compare them with standard spectral ratios of the intense s wave part of weak or strong motion records obtained at the same sites our results showed that microtremor measurements can be used to estimate the dominant period of a site with very acceptable reliability in the range 0 3 to 5 hz the best results were obtained with nakamura s technique which also gives a rough estimate of amplification of seismic waves when the local geology is relatively simple simple numerical simulations indicate that the underlying assumptions of nakamura s technique are consistent with the propagation of rayleigh waves these simple numerical simulations also explain why different researchers have been able to successfully characterize 1d site effects using microtremor records regardless of whether they consider microtremors to consist of surface or body waves our results strongly suggest that the technique by nakamura effectively compensates for source effects in microtremor measurements which eliminates a major limitation to their application in earthquake engineering

microtremor measurements used to map thickness of soft sediments the observations about the behavior of microtremor spectra presented here show that noise measurements can be used as a powerful tool to determine the thickness of soft cover layers the most suitable method for this determination is nakamura s technique which is the ratio of the horizontal component noise spectrum and that of the vertical component i i v spectrum the frequency of the main peak in these spectral ratios correlates well with the sediment thickness at the site using an extensive database of microtremor measurements carried out in the western lower rhine embayment germany it was possible to show that this correlation is clearly valid for a wide range of thickness namely from tens of meters to more than 1000 m a simple formula was derived that for the sediments to be found in the area investigated directly calculates the cover thickness from the frequency of the main peak in the h v spectrum a comparison with calculated resonant frequencies sug gests the relation derived from the noise measurements depending on the velocity depth function of the shear wave classical spectral ratios are shown to be strongly influenced by the noise level and are therefore less reliable in determining the res onant frequency of the subsoil the practical relevance of the investigation is illus trated by means of cross sections constructed from results of the microtremor anal yses which provide a convincing image of the surficial structure of the areas investigated

characteristics of the seismic attenuation in two tectonically active zones of southern europe the seismic energy attenuation in the frequency range of 1 18 hz was studied in the two tectonically active zones of irno valley southern italy and granada basin south east spain data were recorded by short period vertical components seismographs for low magnitude local earthquakes the method of coda waves assuming singles tos scattering approximation was used to calculate the quality factorq from the two data set results show a quality factor increasing with frequency following the empirical lawq qofn qo andn are lower for the irno valley than for granada this result is interpreted in terms of different scattering environments present in the two investigated areas

the three dimensional shear wave structure in the mantle by overtone waveform inversion i radial seismogram inversion summary the three dimensional 3 d shear wave structure of the mantle down to the depth of about 900 km is obtained by inverting waveforms of radial component seismograms radial component seismograms contain large amplitude overtone signals which circle the earth as wave packets and are sometimes called x1 x2 x3 we use data which contain r1 x1 and x2 and filtered between 2 and 10mhz it is shown that unless each seismogram is weighted all seismograms are not fitted uniformly only data from large earthquakes are fitted and the final velocity anomalies are biased by the small number of large earthquake data resolution is good at shallow depths becomes worse in the intermediate depth range between about 400 and 500 km and then becomes better at greater depth ranges 600 900km even though we use only spheroidal mode data velocity anomalies in the shallow structure show excellent correlation with the age of the surface rocks of the earth in the deeper regions between about 600 and 900km south america shows a fast velocity anomaly which may indicate the slab penetration beyond 700 km there another region which shows a fast velocity anomaly is the mariana trench but other subduction regions do not show such features