ground penetrating radar detection of small scale channels joints and faults in the unconsolidated sediments of the atlantic coastal plain the geological characterization of the shallow subsurface in the unconsolidated sediments of the atlantic coastal plain and other unconsolidated sediment regimes may involve jointing faulting and channeling not readily detectable by conventional drilling and mapping a knowledge of these features is required in environmental geotechnical and geomorphological studies ground penetrating radar gpr may be used to routinely map these structures three principal shallow subsurface features are readily detectable using gpr paleochannels joints or fractures and faults the detection of paleochannels is dependent on the scale of the gpr survey and the attitude of the channel within the survey area channel morphological features such as scour surfaces point bars and thalwegs are observable joints and fractures are more difficult to detect depending upon size patterns orientation and fill material vertical joints may not be visible to radar unless they are wider than the sampling interval or are filled with radar opaque materials such as limonite angled joints or fractures may be distinguished by an apparent continuous reflector on the radar profile faulting on radar profiles may be observed by the offset of reflectors the image of the fault plane or the coherent interpretation of a fault system

a review on natural and human induced geohazards and impacts in karst karst environments are characterized by distinctive landforms related to dissolution and a dominant subsurface drainage the direct connection between the surface and the underlying high permeability aquifers makes karst aquifers extremely vulnerable to pollution a high percentage of the world population depends on these water resources moreover karst terrains frequently underlain by cavernous carbonate and or evaporite rocks may be affected by severe ground instability problems impacts and hazards associated with karst are rapidly increasing as development expands upon these areas without proper planning taking into account the peculiarities of these environments this has led to an escalation of karst related environmental and engineering problems such as sinkholes floods involving highly transmissive aquifers and landslides developed on rocks weakened by karstification the environmental fragility of karst settings together with their endemic hazardous processes have received an increasing attention from the scientific community in the last decades concurrently the interest of planners and decision makers on a safe and sustainable management of karst lands is also growing this work reviews the main natural and human induced hazards characteristic of karst environments with specific focus on sinkholes floods and slope movements and summarizes the main outcomes reached by karst scientists regarding the assessment of environmental impacts and their mitigation

application of 2d full waveform tomography on land streamer data for assessment of roadway subsidenceapplication of 2d full waveform tomography roadways are key components of the modern transportation system therefore assessment of roadway subsidence is critical to the health and safety of the traveling public existing seismic refraction and waveform tomography methods can be used for subsidence evaluation however data acquisition time is significant as they require multiple source impacts shots along a test line to mitigate negative impact caused by closing the traffic flow under seismic testing a land streamer seismic testing system and waveform analysis are developed an existing 2 d gauss newton full waveform inversion fwi method is extended for analysis of the land streamer waveform data the main advantage of using land streamer waveform data is that geophones are not coupled to test materials and source receiver offsets are fixed thus the whole test system can be moved along roadway quickly for data acquisition to demonstrate the effectiveness of land streamer waveform data the fwi method was tested on both synthetic and field

ground penetrating radar and its use in sedimentology principles problems and progress abstract ground penetrating radar gpr also referred to as ground probing radar surface penetrating radar subsurface radar georadar or impulse radar is a noninvasive geophysical technique that detects electrical discontinuities in the shallow subsurface

strontium isotope and sequence stratigraphy of the miocene kirkwood formation southern new jersey we use sr isotope stratigraphy to correlate the miocene kirkwood formation of the new jersey coastal plain to the geomagnetic polarity time scale gpts and to ascertain the age of miocene depositional sequences sr isotope stratigraphy confirms diatom biostratigraphy which delineates three kirkwood sequences corresponding to east coast diatom zone ecdz 1 ecdz 2 and ecdz 6 of andrews 1988 sr isotope age estimates of the lowermost sequence ecdz 1 range from 19 2 to 22 6 ma 0 5 m y the middle sequence ecdz 2 ranges from 15 5 to 17 4 ma 0 5 m y a disconformity within ecdz 2 at the belleplain state forest borehole and the wildwood 198a well separates it into two sequences with a possible hiatus from 17 to 16 ma sr isotope age estimates of the upper kirkwood sequence ecdz 6 are not as certain and range from 11 5 to 13 6 ma 0 8 ma a shorter age range of 12 2 13 6 ma for this sequence is supported by its assignment to the d stauracanthus silicoflagellate subzone sedimentation rates were as high as 40 m per million years during deposition of the kirkwood formation suggesting possible tectonic influences on depositional history the timing of lower to middle miocene sequence boundaries from the new jersey coastal plain compares well with other indicators of sea level change including oxygen isotopes miller and others 1991b the global sea level record of haq and others 1987 and the offshore new jersey sequence boundaries of greenlee and others 1992 thus both tectonic and eustatic changes influenced miocene depositional history of the new jersey coastal plain

urban near surface seismic monitoring using distributed acoustic sensing urban subsurface monitoring requires high temporal spatial resolution low maintenance cost and minimal intrusion to nearby life distributed acoustic sensing das in contrast to conventional station based sensing technology has the potential to provide a passive seismic solution to urban monitoring requirements based on data recorded by the stanford fiber optic seismic observatory we demonstrate that near surface velocity changes induced by the excavation of a basement construction can be monitored using existing fiber optic infrastructure in a noisy urban environment to achieve the satisfactory results careful signal processing comprising of noise removal and source signature normalization are applied to raw das recordings repeated blast signals from quarry sites provide free unidirectional and near impulsive sources for periodic urban seismic monitoring which are essential for increasing the temporal resolution of passive seismic methods our study suggests that das will likely play an important role in urban subsurface monitoring

igneous garnet and amphibole fractionation in the roots of island arcs experimental constraints on andesitic liquids to evaluate the role of garnet and amphibole fractionation at conditions relevant for the crystallization of magmas in the roots of island arcs a series of experiments were performed on a synthetic andesite at conditions ranging from 0 8 to 1 2 gpa 800 1 000 c and variable h2o contents at water undersaturated conditions and fo2 established around qfm garnet has a wide stability field at 1 2 gpa garnet amphibole are the high temperature liquidus phases followed by plagioclase at lower temperature clinopyroxene reaches its maximal stability at h2o contents 9 wt at 950 c and is replaced by amphibole at lower temperature the slopes of the plagioclase in boundaries are moderately negative in text t text x text h 2 text o space at 0 8 gpa garnet is stable at magmatic h2o contents exceeding 8 wt and is replaced by spinel at decreasing dissolved h2o the liquids formed by crystallization evolve through continuous silica increase from andesite to dacite and rhyolite for the 1 2 gpa series but show substantial enrichment in feo mgo for the 0 8 gpa series related to the contrasting roles of garnet and amphibole in fractionating fe mg in derivative liquids our experiments indicate that the stability of igneous garnet increases with increasing dissolved h2o in silicate liquids and is thus likely to affect trace element compositions of h2o rich derivative arc volcanic rocks by fractionation garnet controlled trace element ratios cannot be used as a proxy for slab melting or dehydration melting in the deep arc garnet fractionation either in the deep crust via formation of garnet gabbros or in the upper mantle via formation of garnet pyroxenites remains an important alternative despite the rare occurrence of magmatic garnet in volcanic rocks

quantitative quality of distributed acoustic sensing vertical seismic profile data great advances have been made in distributed acoustic sensing das vertical seismic profile vsp data acquisition hardware and software here we capture a quantitative assessment of the quality of das data at a single point in time we apply comprehensive testing methods to determine the reliability of the data and its suitability as a supplement to geophone data or to gain access to wells where it would be difficult to deploy geophones the test measurements are made on das and geophone data which were collected at the same time and in the same well we analyze the first breaks for waveform consistency signal to noise s n ratio and slowness then we examine the corridor stacks for waveform consistency and s n ratio finally we test the properties of the measurement including linearity repeatability reliability and response as a function of the angle of incidence of a seismic wave to the fiber the results show that the das vsp data provide accurate formation slowness logs and reliable ampl

shear wave velocity imaging of the avignonet landslide france using ambient noise cross correlation 1 the avignonet landslide affects a 2 by 2 km area covered by clayey deposits this paper presents the use of the seismic ambient noise cross correlation technique to retrieve a 3 d model of the shear wave velocity of the area seismic ambient noise was recorded during 15 days at 13 stations located on the landslide cross correlations computed between the vertical components of all station pairs allow the retrieval of the rayleigh wave green s functions and the estimation of their group velocity dispersion curves in the 1 7 5 hz frequency range at frequencies lower than 1 5 hz the anisotropy of the wavefield strongly influences the apparent rayleigh wave velocities moreover the analysis of the convergence of the cross correlations shows that at frequencies higher than 5 hz the recording time length was not sufficient for the cross correlation to be stable these 1 7 5 hz passive group dispersion curves are complementary to the ones computed from shot signals in the 3 7 hz frequency range a tomographic inversion of the resulting 1 7 7 hz rayleigh wave group dispersion curves provides local group dispersion curves at each cell of the tomographic grid these are inverted with a neighborhood algorithm to retrieve the 3 d model of the landslide despite the complex wave propagation in the eastern part of the landslide and the sparse ray coverage estimated velocities and first order features are in good agreement with previous investigations

a 20 m middle pleistocene sea level highstand bermuda and the bahamas due to partial collapse of antarctic ice marine deposits at 20 3 m on the tectonically stable coastlines of bermuda and the bahamas support the hypothesis of a partial collapse of the antarctic ice sheet during the middle pleistocene beach sediments fill a sea cave at 22 m in bermuda and horizontal fenestrae filled beds crop out on platforms at two sites as high as 21 m in eleuthera bahamas carbonate beach sands are bound by an early generation of isopachous fibrous cement that is characteristic of a phreatic marine environment amino acid racemization and tims thermal ionization mass spectrometry dates constrain the age of the deposits to between 390 and 550 ka while proxy evidence supports a correlation with oxygen isotope stage 11 this direct geologic evidence of a 20 decrease in polar ice during the middle pleistocene has important implications for the stability of ice sheets during warm interglaciations

quaternary fluvial history of the delaware river new jersey and pennsylvania usa the effects of glaciation glacioisostasy and eustasy on a proglacial river system abstract fluvial glacial and estuarine deposits in the delaware valley record the response of the delaware river to glaciation sea level change and glacioisostasy during the quaternary incision following an early pleistocene glaciation created the present valley which is inset into a pliocene strath and fluvial plain middle and upper pleistocene and holocene deposits were laid down in this inset valley estuarine terraces in the lower valley and bayshore at 20 m probably marine isotope stage mis 11 8 m mis 5e and 3 m mis 5a or c and a fluvial deposit that correlates to offshore mis 3 marine deposits at 20 m are at elevations consistent with glacioisostatic models successive incisions during lowstands in the middle and late pleistocene lengthened deepened and narrowed the channel in the lower valley and shifted the channel westward in delaware bay during mis 2 glaciation from 25 to 18 ka the delaware was diverted to the hudson shelf valley by glacioisostatic tilting most glacial sediment was trapped in fluvial lacustrine valley fills north of the terminal moraine incision of the valley fill was accomplished during the early stage of rebound between 17 and 12 ka drainage to the delaware shelf was restored between 15 and 13 ka as the forebulge collapsed during incision multiple postglacial terraces formed where the valley was perpendicular to rebound contours and so was steepened and elevated northward and a single terrace formed where the valley paralleled the contours and there was no differential elevation or steepening about 65 of the original volume of mis 2 glacial sediment remains in the main valley and most of the eroded volume is in the channel in the lower valley beneath holocene estuarine fill little glacial sediment reached the delaware or hudson shelf overbank deposition on the lower postglacial terrace and modern floodplain spans the holocene the volume of holocene sediment in the estuary and bay yields a basinwide denudation rate of about 20 m my

fluvial evolution of the rhine during the last interglacial glacial cycle in the southern north sea basin a review and look forward this paper presents the current state of knowledge on the evolution and depositional history of the river rhine in the southern part of the north sea basin during the upper middle and late pleistocene and its response to climate change sea level oscillation and glacio isostasy the study focuses on the development of the eemian interglacial lower delta in the central netherlands and its relation to records of climate and sea level rise and uses the saalian and weichselian pre and postdating periods to place its development in context the rhine fluvial system fills the gradually subsiding north sea basin but its development has strongly been affected by the saalian glaciation and its remaining topography ice pushed ridges originating off the limit of maximum glaciation basically divided the central netherlands into two sedimentary depocentres a central depocentre within the former ice limit and a southern depocentre south of it the sedimentary record of the central depocentre including an incised valley fill shows a 20 40m thick stacked sequence consisting of three units the incised valley fill consists of a late saalian to early eemian age lower fluvial unit and a weichselian age upper fluvial unit both composed of coarse grained channel deposits sandwiched in between is a 5 15m thick record composed of fine grained fluvial and estuarine tidal floodbasin and shallow marine deposits it is of eemian interglacial and early weichselian age and comprises transgressive and highstand deposits that show the drowning of a fluvial system inland parts transformed from fluvial to deltaic and estuarine environments and the most downstream parts transformed to a shallow marine embayment preservation of these units occurred despite considerable sea level fall and climate controlled erosion taking place in the last glacial preservation potential was increased by the fact that the rhine system avulsed away to the southern depocentre halfway the weichselian pleniglacial consequently the infill of the southern depocentre is of an entire different nature and last interglacial transgressive or highstand units are hardly preserved because of glaciation and resulting depocentre configuration the netherlands in nw europe thus offers a very good opportunity to study the transgressive interglacial lower deltaic records and falling stage preservation thereof both key elements for understanding sedimentary development over full 100 ky glacial interglacial cycles of climate and base level change 2014 elsevier ltd and inqua

the effect of gauge length on axially incident p waves measured using fibre optic distributed vibration sensing distributed vibration sensing also known as distributed acoustic sensing is a relatively new method for recording vertical seismic profile data using a fibre optic cable as the sensor the signal obtained from such systems is a distributed measurement over a length of fibre referred to as the gauge length in this paper we show that gauge length selection is one of the most important acquisition parameters for a distributed vibration sensing survey if the gauge length is too small then the signal to noise ratio will be poor if the gauge length is too large resolution will be reduced and the shape of the wavelet will be distorted the optimum gauge length as derived here is a function of the velocity and frequencies of the seismic waves being measured if these attributes vary considerably over the depth of a survey then the use of different gauge lengths is recommended the significant increases in data quality resulting from the use of multiple gauge length values are demonstrated using field data

whole rock aminostratigraphy and quaternary sea level history of the bahamas abstract the surficial geology of the tectonically stable bahamian archipelago preserves one of the most complete records of middle to late quaternary sea level highstand cycles in the world however with the exception of deposits from marine isotope substage mis 5e fossil corals for radiometric dating of this rich stratigraphic sequence are rare this study utilizes the previously published independent lithostratigraphic framework as a testing ground for amino acid racemization in whole rock limestone samples at least six limestone soil couplets provide a relative age sequence of events that encompass as many interglacial glacial cycles d alloisoleucine l isoleucine data fall into six clusters or aminozones on the basis of independent dating and the inferred correlation with global mis the ages of several aminozones are known while the ages of others are calculated from calibrated amino acid geochronology this study demonstrates the utility of the whole rock aminostratigraphy method for dating and correlating widespread emergent marine deposits constitutes the first regional geochronological framework for the bahamas and highlights major sea level events over the past half million years

transgressive systems tract development and incised valley fills within a quaternary estuary shelf system virginia inner shelf usa abstract high frequency quaternary glacioeustasy resulted in the incision of six moderate to high relief fluvial erosion surfaces beneath the virginia inner shelf and coastal zone along the updip edges of the atlantic continental margin fluvial valleys up to 5 km wide with up to 37 m of relief and thalweg depths of up to 72 m below modern mean sea level cut through underlying pleistocene and mio pliocene strata in response to drops in baselevel on the order of 100 m fluvially incised valleys were significantly modified during subsequent marine transgressions as fluvial drainage basins evolved into estuarine embayments ancestral generations of the chesapeake bay complex incised valley fill successions are bounded by or contain up to four stacked erosional surfaces basal fluvial erosion surface bay ravinement tidal ravinement and ebb flood channel base diastem in vertical succession these surfaces combined with the transgressive oceanic ravinement that generally caps incised valley fills control the lateral and vertical development of intervening seismic facies depositional systems transgressive stratigraphy characterizes the quaternary section beneath the virginia inner shelf where six depositional sequences sequences i vi are identified depositional sequences consist primarily of estuarine depositional systems subjacent to the transgressive oceanic ravinement and shoreface shelf depositional systems highstand systems tract coastal systems are thinly developed the quaternary section can be broadly subdivided into two parts the upper part contains sequences consisting predominantly of inner shelf facies whereas sequences in the lower part of the section consist predominantly of estuarine facies three styles of sequence preservation are identified style 1 represented by sequences vi and v is characterized by large estuarine systems ancestral generations of the chesapeake bay that are up to 40 m thick have hemicylindrical wedge geometries and occur within large coast oblique trending depressions paleo estuaries style 1 is dominated by fluvial through estuary mouth depositional systems seismic facies 1 4 style 2 sequence preservation represented by sequences iii and ii is dominantly an inner shelf and shoreface succession with a seaward thickening tabular wedge geometry that does not exceed 15 m in thickness these shoreface and inner shelf depositional systems of the upper transgressive systems tract seismic facies 9 and highstand systems tract seismic facies 7 and 11 are not associated with paleo estuaries style 3 sequence preservation is represented by sequence i the holocene sequence it consists of lower transgressive systems tract fluvial estuarine lagoonal and tidal inlet fill deposits seismic facies 1 6 and 8 overlain by upper transgressive systems tract shelf and shoreface sands seismic facies 9 style 3 has a crenulated wedge geometry and is thickest beneath and seaward of the modern chesapeake bay mouth it thins northward and landward onto late pleistocene interfluvial highs on the basinward side of the southern delmarva peninsula

epidote phenocrysts in dacitic dikes boulder county colorado epidote ps21 crystallized early as elongate phenocrysts in late cretaceous rhyodacitic dikes in the vicinity of ward boulder county colorado other unusual phenocryst phases are garnet gr17 24 and muscovite in a xenolith containing kyanite corundum biotite and plagioclase magmatic garnet grew as a rim around xenocrystic pyrope rich py37 garnet the xenolith was derived from a granulite facies zone not represented at the present day erosion surface which is composed of upper amphibolite facies cordierite and sillimanite bearing gneisses the dike magmas were fed not from an immediately underlying batholith but from a magma chamber at a depth corresponding to a pressure of 8 13 kilobars phenocrysts cystallized in the temperature range 800 to 700 c under h2o and o2 activities greater than normal for silicic magmas this occurrence shows convincingly not only that epidote can be magmatic but that it is a possible early crystallization phase in silicic magmas

a study of near source effects in array based spac microtremor surveys summary array based methods for exploiting ambient seismic noise are receiving increasing attention in the literature particularly for use in providing shear wave velocity profiles to assist with simulation of site specific earthquake responses many of these microtremor methods such as the spatial autocorrelation technique spac operate under the fundamental assumption of plane wave propagation of surface waves however when there are significant microtremor sources in close proximity to an array wave front curvature becomes significant and the plane wave assumption becomes a tenuous one this paper explains the use of a simplified geometry based approach to examine the effect of source distance on spac spectra for hexagonal six station and triangular three station arrays the results suggest that near source effects are generally minimal provided that most of the sources are located a distance equal to at least two array radii from the centre of the array although this distance increases when attenuation is considered results of a field trial involving the deliberate use of near sources in proximity to a hexagonal six station array support the findings of the theoretical model near source effects generally result in the measured spac curve being offset to lower frequencies for wavenumbers less than the first secondary maximum of the spac curve kr 0 86r resulting in underestimates of shear velocity values in the inverted layered earth model for the field example shear velocity was underestimated by up to approximately 17 per cent studies of near source effects in a number of theoretical source distributions for hexagonal arrays revealed that cyclic variation in the imaginary spac coefficients are indicative of near source effects although field examples indicate this effect is less significant than the geometric modelling suggests modelling of linear microtremor source distributions intended to represent traffic travelling along a road resulted in less severe near source effects than full 360 azimuthal source coverage a result confirmed by field data model and field studies also indicated that in situations of a dominant close microtremor source of limited azimuthal extent use of a hexagonal six station array significantly mitigates near source effects compared with a similarly aligned triangular three station array

water saturated and undersaturated melting of metaluminous and peraluminous crustal compositions at 10 kb evidence for the origin of silicic magmas in the taupo volcanic zone new zealand and other occurrences

ancient channels of the susquehanna river beneath chesapeake bay and the delmarva peninsula three generations of the ancestral susquehanna river system have been mapped beneath chesapeake bay and the southern delmarva peninsula closely spaced seismic reflection profiles in the bay and boreholes in the bay and on the southern delmarva peninsula allow detailed reconstruction of each paleochannel system the channel systems were formed during glacial low sea level stands and each contains a channel fill sequence that records the subsequent transgression the trunk channels of each system are 2 to 4 km wide and are incised 30 to 50 m into underlying strata they have irregular longitudinal profiles and very low gradients within the chesapeake bay area the three main stem channels diverge from the head of the bay toward the southeast the channels are rarely coincident although they commonly intersect all three main channels pass beneath the southern delmarva peninsula forming an age progression from north oldest to south youngest beneath the peninsula and from east oldest to west youngest beneath chesapeake bay southward progradation of the tip of the delmarva peninsula during interglacial high sea level stands caused southward migration of the mouth of the bay so that the next generation of channels were incised progressively further towards the southwest the youngest paleochannel is clearly of late wisconsinan age about 18 ka and the intermediate one appears to be late illinoian in age or about 150 ka the age of the oldest paleochannel is not well constrained but it is in the range of about 200 to 400 ka the three paleochannel systems imply a dynamic coastal plain environment and at least two previous generations of the chesapeake bay both the chesapeake bay and the southern delmarva peninsula have changed considerably in the past half million years

ground penetrating radar of northern lacustrine deltas ground penetrating radar gpr was used in several selected deltaic sedimentary environments to better understand subsurface stratigraphy and reconstruct former depositional environments the profiles provide high resolution continuous subsurface data on facies thickness and depths orientation of major sedimentary structures postdepositional failure planes and depth of peat deposits field experiments were carried out on six river deltas records from four of the deltas exhibit sedimentary facies a record from one delta shows a possible slump and records from another delta reveal the thickness and stratigraphic relationships of peat deposits the delta types are i sandy wave influenced ii sandy immature wave influenced steeper middle and lower shoreface iii sandy braided and iv gravelly fan foreset in areas of limited subsurface control stratigraphic logs from drill core cutbank exposure or geophysical logs radar profiles can provide big picture perspectives of the subsurface

uranium series coral ages from the us atlantic coastal plain the 80 ka problem revisited abstract uranium series coral ages for emergent units from the passive continental margin us atlantic coastal plain acp suggest sea level above present levels at the end of marine oxygen isotope stage mis 5 contradicting age elevation relations based on marine isotopic or coral reef models of ice equivalent sea level we have reexamined this problem by obtaining high precision 230th 238u and 231pa 235u thermal ionization mass spectrometric ages for recently collected and carefully cleaned acp corals many in situ we recognize samples that show no evidence for diagenesis on the basis of uranium isotopic composition and age concordance combining new and earlier data among those ages close to or within the age range of mis 5 over 85 cluster between 65 and 85 ka bp of the corals that we have analyzed those that show the least evidence for diagenesis on the basis of uranium isotopic composition and age concordance have ages between 80 and 85 ka bp consistent with a mis 5a correlation the units from which these samples have been collected are all emergent and have elevations within 3 5 m of those few units where early stage 5 125 000 ka bp coral ages have been obtained the acp appears to record an unusual history of relative sea level throughout mis 5 a history that is also apparent in the dated coral record for bermuda we speculate that this history is related to the regional near to intermediate field effects of ancestral laurentide ice sheets on last interglacial shorelines of the western north atlantic

near surface characterization using a roadside distributed acoustic sensing array abstract due to the broadband nature of distributed acoustic sensing das measurement a roadside section of the stanford das 2 array can record seismic signals from various sources for example

fiber optic network observations of earthquake wavefields author s lindsey nj martin er dreger ds freifeld b cole s james sr biondi bl ajo franklin jb abstract 2017 american geophysical union all rights reserved our understanding of subsurface processes suffers from a profound observation bias seismometers are sparse and clustered on continents a new seismic recording approach distributed acoustic sensing das transforms telecommunication fiber optic cables into sensor arrays enabling meter scale recording over tens of kilometers of linear fiber length we analyze cataloged earthquake observations from three das arrays with different horizontal geometries to demonstrate some possibilities using this technology in fairbanks alaska we find that stacking ground motion records along 20nm of fiber yield a waveform that shows a high degree of correlation in amplitude and phase with a colocated inertial seismometer record at 0 8 1 6nhz using an l shaped das array in northern california we record the nearly vertically incident arrival of an earthquake from the geysers geothermal field and estimate its backazimuth and slowness via beamforming for different phases of the seismic wavefield lastly we install a fiber in existing telecommunications conduits below stanford university and show that little cable to soil coupling is required for teleseismic p and s phase arrival detection

late quaternary stratigraphy and sea level history of the northern delaware bay margin southern new jersey usa a ground penetrating radar analysis of composite quaternary coastal terraces abstract ground penetrating radar gpr and lithologic data reveal six pleistocene sea level highstand sequences forming two composite terraces along the northern margin of delaware bay in southern new jersey usa the upper terrace 18 to 9 m msl is underlain by four estuarine marine sequences of middle pleistocene age while the lower terrace 6 m msl contains 2 middle to late pleistocene sequences separating the 2 terraces is a variably sloping escarpment cedarville created by erosion during at least 2 high sea level events intensive radar imaging and boring of these 6 unconformity bounded units allows for their interpretation in a sequence stratigraphic context identifying transgressive highstand and regressive phases higher than present sea levels of 14 12 6 and 16 m during the middle pleistocene and 5 m during the middle and or late pleistocene are indicated by these sedimentary sequences suggesting relative stability of this section of the atlantic coastal plain during the past 500 ka gpr analysis of coastal drainage modification reveals a contrasting lowstand sequence of incised paleovalleys supporting the interpretation that these bay margin deposits contain one of the most complete sections of late quaternary highstand stratigraphy in the mid atlantic region for appendix see http www elsevier nl locate quascirev

quaternary marine terraces sea level changes and uplift history of patagonia argentina comparisons with predictions of the ice 4g vm2 model of the global process of glacial isostatic adjustment abstract quaternary marine terraces have been investigated along a 1000 km stretch of the coast of argentinian patagonia fossil mollusc shells most in living position and collected from raised beaches were dated using the u series esr and 14 c methods our analyses show that holocene sea level in this region culminated 7000 to 8000 bp at 6 7 m amsl this beach slightly increases in altitude southward the last interglacial stage 5e was identified at 16 17 m amsl whereas the highest and morphologically most distinctive radiometrically dated terrace at 250 000 to 330 000 bp exists at an elevation of 33 35 m amsl we estimate a constant rate of tectonic uplift of 0 09 m 1000 yr since the middle pleistocene using this estimate of the local rate of tectonic uplift we correct relative sea level r s l observations for the holocene epoch in turn the inferred holocene sea level histories are compared with those predicted using the ice 4g vm2 model of the global process of glacial isostatic adjustment this model accurately predicts r s l history from all sites along the northern part of the east coast of the south american continent venezuela brazil however along the southern part of the coast of argentinian patagonia there is evidence of an influence that is not accurately represented in this version of the model of the global process of glacial isostatic adjustment we suggest that this influence could be connected to the presence of the broad continental shelf that is located offshore of this region but the influence of significant neotectonic uplift cannot be dismissed

the record of major quaternary sea level changes in a large coastal plain estuary chesapeake bay eastern united states abstract seismic reflection surveys of the chesapeake bay combined with geologic mapping and analysis of boreholes on the delmarva peninsula provide evidence of at least three generations of the susquehanna river system and three generations of the chesapeake bay the evidence for ancient courses of the susquehanna river is preserved as three distinct paleochannels and evidence for ancient versions of the chesapeake bay is preserved as three sets of paleochannel fill beneath the bay and three generations of barrier spit deposits on the southern delmarva peninsula the paleochannels represent relative sea level minima and the channel fill and barrier spit deposits represents relative sea level maxima a history of three major marine transgressions is recorded in the stratigraphy preserved in the filled paleochannels and in the overlying barrier spit complexes three systematic progressions from fluvial to estuarine to bay or nearshore marine environments this sea level record seems to be compatible with the saw toothed pattern of the marine oxygen isotope record and with the concept of glacial interglacial terminations it also seems to have a climax character in which most of the preserved evidence is related to the largest terminations and to the extreme sea level positions that bound those terminations the three paleochannel fill and barrier spit complexes appear to correspond to oxygen isotope stages 1 5 and either 7 or 11 the three related paleochannels correspond to stages 2 6 and either 8 or 12

origin structure and exposure history of a wave cut platform more than 1 ma in age at the coast of northern spain a multiple cosmogenic nuclide approach abstract along the asturian coast of northern spain an uplifted wave cut platform extends for 100 km east west the steep cliff which bounds the gently seaward dipping platform to the north increases in height from 30 m in the west to 100 m in the east and reflects the overall eastward increase in platform elevation the southern edge of the 2 4 km wide platform runs along the foothills of the cantabrian mountains as constrained by a high resolution digital elevation model the marine platform which was carved into deformed paleozoic bedrock with abundant quartzite beds is largely covered by weathered marine and continental sediments quartzite samples from flat bedrock outcrops which are currently not covered by sediment or soil yield cosmogenic nuclide concentrations 21ne 10be and 26al that demonstrate a long and complex exposure history including periods of burial with partial or complete shielding from cosmic rays the combination of multiple cosmogenic nuclides yields a minimum age of 1 2 ma for the platform taking into account i the horizontal and vertical extent of the platform ii the high resistance to erosion of the quartzitic bedrock and iii published data on the magnitude of past sea level fluctuations we suggest that the wave cut platform formed in the pliocene subvertical faults cutting the platform at high angles to the coastline offset the southern edge of the platform by 20 to 40 m and reactivate the pre existing anisotropy in the paleozoic bedrock uplift and crustal deformation of the coastal region have occurred after platform formation in the pliocene and may still be active the slow deformation of the northern edge of the iberian plate including the cantabrian mountains may result from the ongoing slow convergence at an incipient subduction zone extending along the coast of northern spain

quaternary shoreline development the northwestern coast of egypt abstract new age estimates for samples representing different sedimentary units of the coastal ridges along el omayid burg el arab northwestern coast of egypt reveal that the coastal first ridge is related to holocene high sea level aminozone a with evidence of recent 0 6 0 1 ka ooid contributions the el max abu sir second ridge appears to be associated with the last interglacial and related to oxygen isotope substages ois 5c 5a beach boulders at the bottom of the gebel maryut third ridge are related to the last interglacial high stand ois 5e while the molluscan and cardium limestones are related to a cardium beach of lagoonal to shallow marine environment this beach represents a coastal barrier which existed between 208 59 to 292 48 ka and is related to aminozones f g and ois 7 9 complex paleosols are developed on the northern flanks of both the second and the third ridges with an estimate age of 67 31 ka and aminozone c these appear related to interstadial conditions at the early last glacial stage the paleosols pink limestone at the top of the khashm el ish fourth ridge show a wide range of ages giving age estimates between 360 140 and 584 317 ka indicating a middle pleistocene age

water saturated magmas in the panama canal region a precursor to adakite like magma generation amphibole while uncommon as a phenocryst in arc lavas is increasingly recognized as a key constituent in the petrogenesis of arc magmas fractional crystallization of water saturated arc magmas in the lower crust can yield substantial volumes of amphibole cumulates that depending on the pressure of crystallization may also contain garnet fractionation of this higher pressure assemblage has been invoked as a possible mechanism in the production of magmas that contain an adakitic signature this study examines newly dated late oligocene 25 37 0 13 ma hypabyssal amphibole rich andesites from cerro patacon in the panama canal region these andesites contain nodules of amphibole cumulates that are 4 6 cm in diameter and are almost entirely composed of 5 10 mm amphibole crystals dominantly ferri tschermakite geochemical variations optical and chemical zoning of the cerro patacon amphiboles are consistent with their evolution in a crystal mush environment that had at least one recharge event prior to entrainment in the host andesite amphiboles hosted within the cumulate nodules differ from those hosted in the cerro patacon andesite and contain consistently higher values of ti we suggest these nodules represent the early stages of fractionation from a water saturated magma cerro patacon andesites have ree concentrations that plot at the most depleted end of central american arc magmas and exhibit a distinctive depletion in the middle ree these geochemical and petrographic observations strongly support significant amphibole fractionation during formation of the cerro patacon andesite consistent with the petrographic evidence fractionation of water saturated magmas is a mechanism by which adakitic compositions may be produced and the cerro patacon andesites do exhibit adakite like geochemical characteristics e g elevated sr y 28 34 however the relatively elevated concentrations of y and hree indicate garnet was not stable in the fractionating assemblage during this early stage of arc development

unconformity bounded stratigraphic units ubsus in an italian alluvial plain area recognizing and dating abstract we studied the coastal zone of the tavoliere di puglia plain puglia region southern italy with the aim to recognize the main unconformities and therefore the unconformity bounded stratigraphic units ubsus salvador 1987 1994 forming its quaternary sedimentary fill recognizing unconformities is particularly problematic in an alluvial plain due to the difficulties in distinguishing the unconformities that bound the ubsus so far the recognition of ubsus in buried successions has been made mostly by using seismic profiles instead in our case the unavailability of the latter has prompted us to address the problem by developing a methodological protocol consisting of the following steps i geological survey in the field ii draft of a preliminary geological setting based on the field survey results iii dating of 102 samples coming from a large number of boreholes and some outcropping sections by means of the amino acid racemization aar method applied to ostracod shells and 14c dating filtering of the ages and the selection of valid ages iv correction of the preliminary geological setting in the light of the numerical ages definition of the final geological setting with ubsus identification of a hypothetical or attributed time range htr or atr for each ubsu the former very wide and subject to a subsequent modification the latter definitive v cross checking between the numerical ages and or other characteristics of the sedimentary bodies and or the sea level curves with their effects on the sedimentary processes in order to restrict also the hypothetical time ranges in the attributed time ranges the successful application of aar geochronology to ostracod shells relies on the fact that the ability of ostracods to colonize almost all environments constitutes a tool for correlation and also allow the inclusion in the same unit of coeval sediments that differ lithologically and paleoenvironmentally the treatment of the numerical ages obtained using the aar method required special attention the first filtering step was made by the laboratory rejection criteria a and b then the second filtering step was made by testing in the field the remaining ages among these in fact we never compared an age with a single preceding and or following age instead we identified homogeneous groups of numerical ages consistent with their reciprocal stratigraphic position this operation led to the rejection of further numerical ages that deviate erratically from a larger homogeneous age population which fits well with its stratigraphic position rejection criterion c after all of the filtering steps the valid ages that remained were used for the subdivision of the sedimentary sequences into ubsus together with the lithological and paleoenvironmental criteria the numerical ages allowed us in the first instance to recognize all of the age gaps between two consecutive samples next we identified the level in the sedimentary thickness that is between these two samples that may represent the most suitable ubsu boundary based on its lithology and or the paleoenvironment the recognized units are i coppa nevigata sands nea htr mis 20 14 atr mis 17 16 ii argille subappennine asp htr mis 15 11 atr mis 15 13 iii coppa nevigata synthem nvi htr mis 13 8 atr mis 12 11 iv sabbie di torre quarto stq htr mis 13 9 1 atr mis 11 v amendola subsynthem mlm1 htr mis 12 10 atr mis 11 vi undifferentiated continental unit uci htr mis 11 6 2 atr mis 9 3 7 1 vii foggia synthem tgf atr mis 6 viii masseria finamondo synthem tpf atr upper pleistocene ix carapelle and cervaro streams synthem rpl subdivided into ixa incoronata subsynthem rpl1 htr mis 6 3 atr mis 5 3 ixb marane la pidocchiosa castello subsynthem rpl3 atr holocene x masseria inacquata synthem naq atr holocene the possibility of recognizing and dating quaternary units in an alluvial plain to the scale of a marine isotope stage constitutes a clear step forward compared with similar studies regarding other alluvial plain areas where quaternary units were dated almost exclusively using their stratigraphic position as a result they were generically associated with a geological sub epoch instead our method allowed a higher detail in the timing of the sedimentary processes for example mis 11 and mis 5 5 deposits have been recognized and characterized for the first time in the study area highlighting their importance as phases of sedimentation

the potential of das in teleseismic studies insights from the goldstone experiment author s yu c zhan z lindsey nj ajo franklin jb robertson m abstract 2019 american geophysical union all rights reserved distributed acoustic sensing das is a recently developed technique that has demonstrated its utility in the oil and gas industry here we demonstrate the potential of das in teleseismic studies using the goldstone optical fiber seismic experiment in goldstone california by analyzing teleseismic waveforms from the 10 january 2018 m7 5 honduras earthquake recorded on 5 000 das channels and the nearby broadband station gsc we first compute receiver functions for das channels using the vertical component gsc velocity as an approximation for the incident source wavelet the moho p to s conversions are clearly visible on das receiver functions we then derive meter scale arrival time measurements along the entire 20 km long array we are also able to measure path averaged rayleigh wave group velocity and local rayleigh wave phase velocity the latter however has large uncertainties our study suggests that das will likely play an important role in many fields of passive seismology in the near future