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Postgraduate Research Symposium

Abstract Book

Leicester University

12th May 2017

POSTGRADUATE RESEARCH SYMPOSIUM – May 2017

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PROGRAMME

0915 – 0955 Registration and Coffee

0955 – 1000 Opening Address

1000 – 1020 Ground-penetrating radar survey in Ireland – overkill or a viable asset for archaeological survey? A Green

1020 – 1040 Kurtosis statistics as an indicator of the precision of migration velocity analysis. A Harding and A Booth

1040 – 1100 Predicting optimal forensic remote sensing and near-surface detection methods. M.I. Quick

1100 – 1115 Poster Introductions

1. Assessing surface and subsurface hydrological contamination at an abandoned metal mine in Mid-Wales, UK. E Hudson

2. Geophysical ground survey investigation for the possible HS2 route through Rugeley, Staffordshire, UK. J Francis and Z. Lloyd.

3. A preliminary Ground Penetrating Radar study of fluvial architectures at Spireslack, Ayreshire, Scotland. JT Ainsworth, AJ Mitten and JK Pringle

1115 – 1140 Break

1140 – 1200 Monitoring subsidence related to relict salt mines using long-term time-lapse microgravity, Marston, Cheshire, UK. CJ Rowell and JK Pringle

1200 – 1220 Geophysical indicators of slope stability at the Hollin Hill Landslide Observatory: initial findings from repeated geophysical surveys. J Whiteley

1220 – 1240 A hydrogeological assessment of a small peat bog in South Wales, using an integrated approach. E Hudson

1240 – 1300 Improved characterisation and modelling of measurement errors in electrical resistivity tomography (ERT) surveys. CM Tso, A Binley and O Kuras

1300 – 1305 Morning Closing Remarks

1305 – 1430 Sponsored Lunch and Poster Viewing

1440 – 1500 Integrated geophysical methods in meteorite impact investigation: case studies of Mahsuri Ring, Langkawi and Bukit Bunuh, Perak, Malaysia. H Saleh, AR Samsudin, U Umar Hamzah, MAA Jelani, MH Arifin and N Sulaiman

1500 – 1520 Subglacial Aquifer Characterisation using Multichannel Analysis of Surface Waves and Time-Domain Electromagnetic Techniques. S Prise, A Booth, P Livermore and J West.

1520 – 1540 Understanding how valley-glacier overdeepenings affect seasonal and glacial dynamics. W Higson

1540 – 1600 Quantum Technology gravity sensors – first steps to aerial sensing. D Roberts, L Earl, M Wright, M Uddin, N Metje and M Holynski

1600 – 1630 Closing comments and Awards


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Ground-penetrating radar survey in Ireland – overkill or a viable asset for archaeological survey?

Ashely Green ([email protected])

Department of Archaeology, Anthropology and Forensic Science, Faculty of Science and Technology, Bournemouth University, Poole, Dorset, UK BH12 5BB

Modern rubbish and ferrous contamination often hinder data interpretability in

archaeogeophysical surveys, especially in built environments. In Ireland groundwater

retention and high attenuation materials often negatively impact the potential depth

of investigation and further inhibit data interpretability. A majority of geophysical

surveys in Ireland have been conducted on national road schemes with passive

magnetic techniques (Bonsall et al. 2014). Recently, however, there has been

resurgence in incorporating high-resolution geophysical survey into research

frameworks as a means to identify new sites and target excavations. As a result,

further analysis of the merits of ancillary techniques, such as ground-penetrating

radar (GPR), and higher resolution survey are necessary.

To ascertain the viability of high-resolution GPR surveys for delineating large

structural and small non-structural anthropogenic features the Black Friary (County

Meath) and Forth Maigh Leana (County Offaly) were surveyed using multiple

techniques (GPR, gradiometry, and electromagnetic induction). GPR, a rarely used

technique, proved useful in detecting targets of interest and offered improved data

visualization and interpretability on these sites, thus indicating its potential value to

subsequent surveys.

Figure 1: GPR data demonstrating a decline in resolution and interpretability as the traverse interval increases from 0.10m to 0.20m and 0.50m (left to right)


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Further investigations of the practicality of GPR surveys in Ireland will be conducted

in counties Meath and Offaly, with extension to other regions with variable local

geology.

Reference: Bonsall J, Gaffney C, and Armit I (2014). Preparing for the Future: A reappraisal of archaeo-

geophysical surveying on National Road Schemes 2001-2010. University of Bradford report for the National

Roads Authority, 1-151.


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Kurtosis statistics as an indicator of the precision of migration velocity

analysis

Anne Harding ([email protected]) and Adam Booth

School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK.

Ground-penetrating radar (GPR) is a well-established technique for detailed and

continuous imaging of the subsurface, for purposes including archaeology. Although

GPR quality is often suitable for archaeological interpretation, the accuracy of the

implied subsurface structure can be limited. While migration algorithms can improve

this, the implementation of migration is often compromised because i) migration and

depth velocity are based on a single velocity estimate from common-offset GPR

data, and ii) the effect of topography on the migrated output is often neglected.

These compromises can be jointly circumvented using an approach to migration

velocity analysis (MVA; Allroggen et al., 2015) that honours topographic variation.

However, quantification of the success of each migration scheme is often determined

by subjective methods. Here, we present the use of the kurtosis statistic to objectify

the performance of migration. Kurtosis is a statistical property of the amplitude

distribution of a signal (Langet et al., 2014) and has been used in seismic reflection

processing to find the “best-focussed” parts of a migrated seismic image (Burnett

and Fomel, 2011). Since migration at the correct velocity should focus a hyperbola in

a GPR profile at its apex (Grasmueck et al., 2005) and reduce amplitudes elsewhere

in the profile, the amplitude distribution of the GPR profile should become less

outlierprone, resulting in a higher kurtosis. Therefore, the kurtosis approach can be

implemented to GPR to provide an objectified way of examining the performance of

MVA, determining the optimal migration velocity for the subsurface and evaluating

the precision with which this is calculated.

We consider the implementation of migration schemes incorporating topography to

archaeological GPR data recorded close to the site of Old Scatness broch

(Sumburgh, Shetland; Dockrill et al, 2010), and use the kurtosis statistic to

objectively evaluate their performance. Figure 1 depicts a diffraction hyperbola,

believed to correspond to a modern service through the western end of the site.

Kurtosis analysis of this extract of GPR data evaluates an optimal migration velocity

of 0.0978 m.ns-1, with precision of ± 0.0019 m.ns-1 when topography is incorporated.

Kurtosis statistics provide a means of assessing the reliability of a migrated image.

However, they may also provide an important source of precision information where


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migration velocities are used for estimating quantitative properties (e.g., in the

evaluation from pipe radius from diffraction curvature (Shihab et al., 2005)).

Figure 1: Application of kurtosis as a method of quantifying the performance of migration: (a) Example

500 MHz GPR profile from the acquisition at Old Scatness. Red box indicates extracted area of profile

containing diffraction hyperbola believed to be caused by a modern service, on which kurtosis

analysis was performed; (b) Kurtosis analysis on the profile extract from (a), where incorporation of

topography results in an evaluated optimal migration velocity of 0.0978 ± 0.0019 m.ns-1.

References

Allroggen, N., Tronicke, J., Delock, M. and Boniger, U. 2014. Topographic migration of 2D and 3D ground-

penetrating radar data considering variable velocities. Near Surface Geophysics, 13(3), pp. 253-259.

Burnett, W. and Fomel, S. 2011. Azimuthally anisotropic 3D velocity continuation. International Journal of

Geophysics, 2011. p. 8 (Article ID 484653).

Dockrill, S.J., Bond, J.M., Turner, V.E., Brown, L.D., Bashford D.J. Cussans, J.E. and Nicholson, R.A. 2010.

Excavations at Old Scatness, Shetland, Volume 1. Shetland Heritage Publications, 978-0-9557642-5-7.

Grasmueck, M., Weger, R. and Horstmeyer, H. 2005. Full-resolution 3D GPR imaging. Geophysics, 70(1), pp.

K12-K19.

Langet, N., Maggi, A., Michelini, A. and Brenguier, F. 2014. Continuous Kurtosis-based migration for seismic

event detection and location, with application to Piton de la Fournaise Volcano, La Réunion. Bulletin of the

Seismological Society of America, 104(1), pp. 229-246.

Shihab, S. and Al-Nuaimy, W. 2005. Radius estimation for cylindrical objects detected by ground penetrating

radar. Sensing and Imaging, 6(2), pp. 151-166.


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Predicting optimal forensic remote sensing and near-surface detection

methods

Megan Ivy Quick ([email protected] / [email protected])

Natural Sciences and Psychology, Liverpool John Mores University, Liverpool, L3 3AF, UK.

Police investigators need to locate buried forensic targets, such as clandestine

graves, accurately, quickly and efficiently. Remote sensing and near-surface

detection methods, though increasingly used in criminal investigations, are not

always successful in locating clandestine graves, especially in variable terrains and

climates. As Davenport (2001) states “there is no remote sensing method that will

consistently find a body or physical evidence”. At present poor choices of detection

methods are sometimes made either because of personal preference, what

instruments are available or through unguided trial and error, resulting in poor

outcomes and wasted time. There has been little published research on choosing

optimum remote sensing methods for a particular site and evidence being sought.

This research therefore aims to build and test a computer-based system which will

rank remote sensing detection methods by considering the properties of the target

and its environment, thus improving detection method choices and the rate of

recovery of buried targets. The research began by assembling current best survey

practices by a literature review and approaching expert surveyors from forensic

science and archaeology, to collate a database of what methods are currently being

used to detect buried forensic targets.

The aim of the research is to bridge the gap in the research by encouraging the flow

of information to improve the computer-based system by building wider relationships

across the professional forensic field. The intention is to create closer inter-

disciplinary collaborations and, produce standardised and improved search

protocols.

Reference: Davenport GC, (2001). Remote sensing applications in forensic investigations. Historical

Archaeology, 35(1), 87-100.


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Monitoring subsidence related to relict salt mines using long-term time-lapse

microgravity, Marston, Cheshire, UK

Cathrene J. Rowell ([email protected]) and Jamie K. Pringle

School of Geology, Geography and the Environment, William Smith Building, Keele

University, Keele, Staffs, ST5 5BG, UK.

The Cheshire Basin contains >4.5km of Permo-Triassic red beds, including the

Mercia Mudstone Group (MMG) which accumulated in playa and tidal-flat

environments. The MMG is the host to two major halite formations: The Northwich

and Wilkesley Halite formations, which have been commercially exploited. Both rock

salt and brine has been extracted from mainly two horizons of the Northwich Halite

Formation in the Cheshire Basin in various locations, and rock salt is still mined in

nearby Winsford, Cheshire.

Surface subsidence resulting from salt mining and brine pumping in Northwich, and

the surrounding areas in Cheshire, has occurred since Medieval times. This has

varied in severity, with evidence of subsidence ranging from topographic

depressions to catastrophic surface collapse from the mid-18th Century onwards.

To detect, characterise and monitor areas susceptible of subsidence, near-surface

geophysics has been applied. A section of the Trent and Mersey Canal, in Marston

(Northwich), crossing 3 abandoned salt mines has been the focus of long-term

microgravity surveys for >10 years. The data collected over this period shows

consistent, deepening negative anomalies at the margin between the Adelaide and

Old Marston relict mine workings, as opposed to over the mines themselves. By

correlating microgravity data with mine plans, boreholes and sedimentary logs, 2D

gravity models have been produced: the anomalies are interpreted as upwardly

propagating voids, and associated collapse material. A void feature at the point of

the microgravity excursion has been confirmed by intrusive investigations. Finally,

investigation of the canal water depths and the underlying silt accumulation on the

canal floor has been undertaken to ascertain any connection to underlying mines

and potential canal collapse. This study further demonstrates the importance of time-

lapse microgravity surveys to facilitate the identification and monitoring of at-risk

areas, with a view to mitigating the risk of catastrophic surface subsidence.


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Geophysical indicators of slope stability at the Hollin Hill Landslide

Observatory: initial findings from repeated geophysical surveys

James Whiteley ([email protected])

British Geological Survey, Keyworth, Nottingham, NG12 5GG, UK

Infiltration of rainwater into landslide systems due to increased effective rainfall is

one of the leading contributing factors to the failure of unstable slopes in the UK. An

increase in rainfall intensity in recent years elevates the likelihood of slope failure,

and in turn increases risk from landslide hazards. Preventative remediation of all

potential slope failures is an unfeasible approach to solving the problem, and

therefore robust methodologies are required for long-term assessment of unstable

slopes in order to predict and manage these future failure events.

This presentation shows the initial findings from some of the first combined surveys

that have been undertaken as part of a PhD project at the BGS landslide observatory

based at Hollin Hill, North Yorkshire. The project focuses on the monitoring of the

Hollin Hill landslide using non-intrusive geophysical methods. The approaches used

include active and passive seismic methods, including P-wave and S-wave seismic

refraction tomography (SRT), multichannel analysis of surface waves (MASW) and

permanent broadband seismometer stations, integrated into the ongoing programme

of research using a permanently installed electrical resistivity tomography (ERT)

array at the site. Ultimately the project aims to characterise and observe changes in

subsurface properties that precede landslide failure, using seismic methods to inform

on geo-mechanical property changes, and geo-electrics to monitor variations in

hydrodynamics linked to seasonal variations in climate.

The Hollin Hill site comprises a slow moving earth slide-earth flow within the Lower

Jurassic Lias Group, and initial seismic refraction surveys have shown good

agreement with the previous geological and geomorphological models of the site

(Figure 1).


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Although the slope is subject to constant creep processes, discrete failure events at

the landslide are primarily driven by seasonal climatic variation, with larger failure

events related to water infiltration more common in the winter and spring months.

Reference: Merritt AJ, Chambers JE, Murphy WE, Wilkinson PB, West LJ, Gunn DA, Meldrum PI, Kirkham M

and Dixon N, (2013). 3D ground model development for an active landslide in Lias mudrocks using geophysical,

remote sensing and geotechnical methods. Landslides, 11(4), 537-550.


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Peatland Hydrology: A future at risk

A hydrogeological assessment of a small peat bog in South Wales, using an

integrated approach

Emily Hudson ([email protected])

College of Science, Swansea University, Swansea, SA2 8PP, UK

Pyllau Cochion peat bog in Carmarthenshire, Wales, represents one of the most

southerly and marginal peatlands in the UK. Recognized for the crucial role they play

in greenhouse gas cycling; peatlands are particularly effective carbon sequesters.

However, with predicted climatic changes, the future of these important ecosystems

is potentially at risk.

This project aims to carry out a hydrogeological assessment of this small peatbog

using an integrated approach. Water is the key modulator of peatland accumulation

and subsequent carbon storage capacity, by producing the saturated conditions

necessary for the formation of peat. If the water table becomes unstable, active

accumulation will cease and existing peat will be exposed to the atmosphere.

Oxygenation of peat enables full decomposition, which could lead to the catastrophic

emission of CO₂. The integrated approach aims to use a variety of techniques,

including slug-testing, permeameters, piezometers and water sampling; to elucidate

the geometry, anatomy, hydrology and quality of the peatland. This in turn provides

the necessary input parameters for a groundwater flow model. It is this model which

will be used to assess the current and future hydrogeological functioning of the bog,

as well as whether factors such as microtopography, vegetation, fire, and seasonality

play modulating roles.

Geophysical methods were utilized, with Ground Penetrating Radar (GPR) used to

locate the base of the peat. Manual probing showed basal depths ranging from 30-

720 cm, meaning a 30 MHz antenna was chosen to ensure adequate signal depth

penetration. Eight transects were completed, covering the bog in six parallel and two

perpendicular lines. By recording the two-way travel time (TWTT) of returned signals

at 1m intervals along each transect, the base of the peat was located in all cases.

The strongest reflection seen in all profiles was taken to be indicative of the peat-

mineral soil interface (Fig. 1). As the bog is underlain by clay, it was supposed that

the abrupt change in water content and bulk density at the basal interface was

responsible for producing such a strong reflection. Two steep basins were also

found, with maximum basal depths reaching 9 m. Internal reflections were seen

within the larger of the two basins, at around 350 cm. These were proposed to be a


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result of a change in peat type, from humousy to more herbaceous; with the change

in bulk density creating the reflections in the radar profiles.

By employing geophysics to locate the base, the geometry of the bog can be

inputted to form the basis of the groundwater flow model. Furthermore, initial volume

estimates have also been made. This shows how geophysical techniques have been

integral to the project so far. Other techniques, such as Electrical Resistivity

Tomography (ERT) and Self Potential (SP) surveys, are being considered as

additional geophysical techniques which may be employed to help better understand

where the majority of flow occurs within the bog.

Figure 1 – Radar transect (T2) taken from Pyllau Cochion, as displayed NE to SW. It is clear

that the basal depths steeply increase within the basin, with strong reflections returned even

where the peat thickness reach around 7 m. The internal reflections can also be seen within

the basin, with the slightly weaker reflections insinuating that it is still peat, yet just of a

different type.


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Improved characterisation and modelling of measurement errors in electrical resistivity tomography (ERT) surveys

Chak-hau Michael Tso ([email protected])1, Andrew Binley1, and Oliver Kuras2

1 Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK

2 British Geological Survey, Keyworth, Nottingham, NG12 5GG, UK

Measurement errors can play a pivotal role in geophysical inversion. Most inverse

models require users to prescribe or assume a statistical model of data errors before

inversion. Wrongly prescribed errors can lead to over- or under-fitting of data,

however, the derivation of models of data errors is often neglected. With the

heightening interest in uncertainty estimation within hydrogeophysics, better

characterisation and treatment of measurement errors is needed to provide improved

image appraisal.

Here we focus on the role of measurement errors in electrical resistivity tomography

(ERT). We have analysed two time-lapse ERT datasets: one contains 96 sets of

direct and reciprocal data collected from a surface ERT line within a 24h timeframe;

the other is a two-year-long cross-borehole survey at a UK nuclear site with 246 sets

of over 50,000 measurements. Our study includes the characterisation of the spatial

and temporal behaviour of measurement errors using autocorrelation and correlation

coefficient analysis. We find that, in addition to well-known proportionality effects,

ERT measurements can also be sensitive to the combination of electrodes used, i.e.

errors may not be uncorrelated as often assumed. Based on these findings, we

develop a new error model that allows grouping based on electrode number in

addition to fitting a linear model to transfer resistance.

The new model explains the observed measurement errors better and shows

superior inversion results and uncertainty estimates in synthetic examples. It is

robust, because it groups errors together based on the electrodes used to make the

measurements. The new model can be readily applied to the diagonal data weighting

matrix commonly widely used in common inversion methods, as well as to the data

covariance matrix in a Bayesian inversion framework. We demonstrate its application

using extensive ERT monitoring datasets from the two aforementioned sites.


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Integrated geophysical methods in meteorite impact investigation: Case studies of Mahsuri Ring, Langkawi & Bukit Bunuh, Perak, Malaysia.

Hardianshah Saleh1,3 ([email protected]), A.R. Samsudin2, U. Umar Hamzah2, M.A.A. Jelani1,4, M.H. Arifin2 and N. Sulaiman2

1 School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK

2 Universiti Kebangsaan Malaysia, 43600 UKM, Bangi Selangor, Malaysia

3 Universiti Malaysia Sabah, Jalan UMS, 88400, Kota Kinabalu, Sabah, Malaysia

4 Universiti Malaysia Terengganu, 21030 Kuala Terengganu, Terengganu, Malaysia

The evidence of shock metamorphisms (suevite breccia) at Bukit Bunuh (BB) in

Lenggong, Perak and circular geomorphology in Mahsuri Ring (MR), Langkawi

indicates of meteorite impact. Integrated geophysical methods – resistivity imaging,

seismic refraction, gravity and magnetic survey – were carried out to investigate the

existence of impact crater with covering approximately 10 km2 for both case studies

area.

The results of Bouguer anomaly map showed that BB impact crater has a diameter

of approximately 2.5 km and shows good correlation with result from seismic and

resistivity, which located at the centre of the interpreted crater. The impact structure

was successfully modeled as a complex impact crater with maximum depth of about

300 m. The Bouguer anomaly map also shows the possible occurrences of at least

two more impact craters located in the northeast and southeast areas of the BB

crater and these structures need further investigation for confirmation. While for MR

cases, Bouguer gravity map shows relatively low negative anomaly with rounded

shaped contour around the suspected crater area. This anomaly was interpreted as

a remnant of meteorite impact structure with distorted shaped crater in the study

area. The structure of the crater interpreted has a diameter of approximately 1.5 km.

The impact structure has been modelled as a simple type crater in order to

determine the thickness of the low density sedimentary fill.

In conclusion, integrated geophysical method shows the possible occurrences of at

least two impact craters located at Bukit Bunuh with complex crater structure. While

for Mahsuri Ring cases, there is an indication of subdued magnetic anomaly in the

region within the impact crater and interpreted as simple crater structure.


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Subglacial Aquifer Characterisation using Multichannel Analysis of Surface Waves and Time-Domain Electromagnetic Techniques

Siobhan Prise ([email protected]), Adam Booth, Phil Livermore, Jared West

School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK

The contribution of glaciers and ice-sheets to global sea level is becoming

significantly important as more evidence suggests this will increase in the coming

decades (Bell, 2008). The subglacial hydrology exerts a substantial control on the

flow dynamics of glaciers and ice masses (Bell 2008). Surface meltwater entering

moulins, crevasses, and fractures is channelled to the bedrock through a

combination of storage elements and transport pathways; however both englacial

and subglacial drainage systems are imprecisely known (Rennermalm et al. 2013).

Subglacial water influences ice flow by modulating basal friction, the strength of

subglacial sediments and its potential to deform. Glacio-geophysical methods are

needed for monitoring, imagining and mapping subglacial sediments and drainage

system.

This project is focused on developing non-conventional glacio-geophysical

methodologies: Multichannel Analysis of Surface Waves (MASW) and Time-Domain

Electromagnetic (TEM) methods for acquiring and interpreting field observations of

the subglacial environment. A small amount of unfrozen water in sediment pores can

lead to large S-wave velocity (Vs) decreases; therefore the Vs profile provides useful

information on water content and degree of freezing in sediment pores (Johansen et

al 2003). Additionally water has a very low resistivity compared to ice and frozen

sediments. Electrical resistivity values decrease by several orders of magnitude

when ice melts or liquid water is present in sediment pores. This allows resistivity to

be used as an indicator of moisture content and temperature of subsurface

materials.

A combined analysis, using a joint inversion technique, of MASW and TEM can

quantify the groundwater contents of subglacial sedimentary basins exploiting the

fact both data types are sensitive to porosity, permeability and liquid water content.

An MASW feasibility study has been conducted using modelled synthetic data

(example shown in Figure 1) and Antarctic MIDAS seismic data (a NERC funded

project to identify the impact of melt on ice shelf dynamics and stability). This tested

different survey design parameters for acquiring MASW seismic to identify properties

of the subglacial sediment at Midtdalsbreen, an outlet glacier of the

Hardangerjøkulen ice cap. Active source seismic data has been acquired on


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Midtdalsbreen glacier using survey design parameters established from the MASW

feasibility study and a hammer and plate source.

The presentation will include: conclusions from the feasibility study, preliminary

results from the first field campaign at Midtdalsbreen, and implications for future

study.

Figure 1. a) 1D block model with soft sediment layer (low velocity zone) at 20m depth b) MASW

Synthetic Shot gather of 1D model using the Discrete Wavenumber method. c) Frequency-phase

velocity plot showing dispersion curve, with picks, for the modelled shot gather. The blue lines

represent the maximum threshold frequency for the modelled survey design with 5m receiver spacing.

References

Bell RE (2008). The role of subglacial water in ice-sheet mass balance. Nature, 1, 297-304.

Johansen TA, Digranes P, van Schaak M and Lønne I (2003). Seismic mapping and modeling of near-surface

sediments in polar areas. Geophysics, 68(2), 566-573.

Rennermalm AK, Moustafa SE, Mioduszewski J, Chu VW, Forster RR, Hagedorn B, Harper JT, Mote JL, Robinson

DA, Shuman CA, Smith LC and Tedesco M (2013). Understanding Greenland ice sheet hydrology using an

integrated multi-scale approach. Environmental Research Letters, 8, 015017.


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Understanding how valley-glacier overdeepenings affect seasonal and glacial dynamics

Will Higson ([email protected])

School of Geography, University of Sheffield, Winter Street, Sheffield, S10 2TN, UK

Understanding glacial dynamics is a very complex issue that is of prime importance

for understanding contribution of ice sheet and glacier melt to sea level. Numerous

interacting factors are responsible for how and why a glacier flows the way it does,

including for example, basal debris, meltwater and climate. Despite overdeepenings

in the bedrock topography being considered commonplace in glacial environments,

the processes within them are still poorly understood. Alpine glaciers offer easier

access than that of ice sheets and therefore it is considered that from investigating

the conditions where ponding occurs within valley glaciers that the work done can be

extrapolated and scaled up to ice sheet levels.

Overdeepenings can cause certain phenomenon to occur at the ice/bed interface,

such as supercooling or ponding. These processes occur due to the relative slope

ratios of the ice surface to the bedrock. In order that the effects of these processes

can be estimated and examined, data needs to be gathered as to the relative

changes and morphology of the glacier. A multifaceted methodology combining high

resolution photogrammetry of the surface as well as bedrock topography estimations

is required. The fieldsite of the bottom 2 km of Findelen glacier was chosen, due to

evidence from previous works as well as glacial modelling, that two distinct

overdeepenings are present.

A GPR survey of the area was carried out in early February due to the low

temperatures and therefore less meltwater equating to clearer results of bedrock

from the GPR. Using MALA Ground penetrating radar, it was possible to measure

the bedrock topography beneath the glacier to a higher degree of accuracy than

estimates from the previously used glacial ice thickness models. It is the hope that

this, combined with high quality digital elevation models (DEMs) and 3D

orthomosiacs achieved from unmanned aerial vehicles (UAVs) will give us the best

estimates as to how the bedrock beneath glaciers can affect the dynamics of the

glacier itself both in terms of surface velocities and melt on seasonal and annual

timescales. It is hoped that from these fieldworks and coming fieldworks in the

summer, that a complete estimate and 3D model can be produced of the bedrock

topography beneath Findelen Glacier, and glacial processes confirmed.


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Quantum Technology gravity sensors – first steps to aerial sensing

Daniel Roberts1 ([email protected]), Luuk Earl1, Michael Wright1, Mohammed Uddin1, Nicole Metje, Michael Holynski1.

1 UK National Quantum Technology Hub, Sensors and Metrology, School of Physics and Astronomy, University of Birmingham, Birmingham, B15 2TT

2 School of Civil Engineering, University of Birmingham, Birmingham, B15 2TT

The UK Government has recognised that recent advances in science, engineering

and manufacturing capabilities presents a major national opportunity. The Quantum

Technology (QT) Hub in Sensors and Metrology at the University of Birmingham is

one of four QT hubs created within the National QT Programme. The University of

Birmingham is developing QT gravity sensors to look through the ground which have

a significantly higher sensitivity, enabling them to detect features currently

undetectable – such as buried tunnels and mine workings. Research to date has

indicated a 1.5 – 2.0 increase in detectability, bringing some buried features now into

view (Boddice et al., 2016). This has the potential to revolutionise the way in which

geophysical investigations are undertaken.

Microgravity data is currently collected by geophysicists, but for most commercial

applications relies on the microgravity sensor being placed on the ground surface to

take measurements in a grid making surveys over large areas time consuming. In

addition, challenges exist in mountainous regions with little-to-no access or densely

populated cities that are congested with people, vehicles and buildings. These

difficulties can be overcome by using aerial surveys. This paper will highlight the

initial steps undertaken to develop a drone to include a QT gravity sensor. One key

challenge is to provide a stable environment for a magneto-optical trap (MOT) that

can be mounted onto the bottom of a drone (Figure 1) and flown over an area to

collect readings.

Figure 1. Magneto-optical trap (MOT) mounted to the bottom of a Vulcan Raven UAV

mailto:[email protected]


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The MOT is the key element for a QT gravity sensor as it traps the ultra-cold atoms

in a stable environment and ultimately interrogate these with a laser. The next stage

of this project is to develop an interferometer small enough and efficient enough to

measure the minute variations of gravity.

Reference: Boddice D, Metje N, Tuckwell G (2016). The potential for quantum technology gravity sensors.

European Geosciences Union General Assembly, April, Vienna, Austria.


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Assessing surface and subsurface hydrological contamination at an

abandoned metal mine in Mid-Wales, UK

Emily Hudson ([email protected])

College of Science, Swansea University, Swansea, SA2 8PP, UK

The mining and processing of metal ores in the UK has left behind a legacy of

environmental degradation, and the abandonment of metal mines still poses a

significant contamination threat to terrestrial and fluvial environments. Esgair Mwyn

is an abandoned metal mine in Mid-Wales, which has been mined since Roman

times, primarily for lead and zinc. However, since its abandonment, the site has been

discharging waters loaded with heavy metals downstream into the Afon Meurig,

contributing to its heavy metal concentrations that far exceed acceptable

Environmental Quality Standards (EQS) established under the Water Framework

Directive (WFD). Therefore, the aim of this project was to work in conjunction with

Natural Resources Wales (NRW) to investigate surface and subsurface hydrological

contamination at the site, in the hopes of informing future remediation strategies.

To investigate the above ground hydrological contamination occurring, salt water

dilution gauging was performed. This allowed the flow rates of the primary surface

streams at the site to be calculated, and this information was subsequently combined

with the results of water sampling. From this, the daily metal export from the site was

quantified, and the inputs of the main streams apportioned. It was discovered that

876 g of dissolved Pb, Zn, Cu and Cd were leaving the site each day in the Nant y

Garw. This watercourse is fed by the four primary streams running over the site,

each of which contributed varying proportions to the overall metals seen.

Subsurface hydrological contamination was investigated using geophysics. Electrical

Resistivity Tomography (ERT) was employed to study the subsurface of three main

areas of the site: the tailings lagoon wall, main spoil heap, and northern field; and

this was done along eight transects. Seepage was proposed to be occurring within

the tailings lagoon wall, thus allowing waters with extremely high heavy metal

concentrations to escape downstream. The spoil heap surface was inferred to be

preventing mass saturation and mobilization of water, with the loose, dry surface

impeding percolation into the spoil. The large field adjacent to the main spoil heap

was found to have high heavy metal mobilization potential, due to the extreme

saturation of the subsurface, and the presence of spoil deposits at the heads of

several surface streams. However, the morphological characteristics of the field

mean that this potential is not fully realized, and the area is acting as a passive

wetland treatment type system.


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By utilizing geophysical and hydrological investigative techniques, both surface and

subsurface hydrological contamination at the site was calculated and apportioned.

This led to several proposals for remediation of the site, including diversion ditches

and channelization, capping of the spoil heap, wetland establishment, as well as

both passive and active water treatment systems.

Figure 1 – Resistivity Model of the tailing lagoon wall. Dual layer structure can be seen, with

resistivity increasing with depth. Low resistivity zones at either end of the profile correlate to

overland flow streams and a preferential seepage plane.


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Geophysical ground survey investigation for the possible HS2 route through

Rugeley, Staffordshire, UK

James Francis and Zach Lloyd ([email protected])



A multi-geophysical and geotechnical site investigation was conducted along a

portion of the proposed High Speed 2 (HS2) corridor near Rugeley, Staffordshire.

The investigation focused on characterising the upper layers of the superficial

geology as well assessing their potential to cause geotechnical issues following the

construction of HS2. The area’s geology consists of Alluvium and river terrace

deposits derived from the River Trent that overly mudstones of the Mercia Mudstone

group and Sandstone of the Bromsgrove Sandstone Formation. The study examined

areas of soft soils, gravel deposits, possible shallow sedimentological structures,

water table variations and a possible bedrock horizon.

Geophysical data was collected using Electrical Resistivity Tomography (ERT) and

Ground Penetrating Radar (GPR) to visualise the subsurface. Geotechnical data was

gathered using a PANDA Dynamic Cone Penetrometer (CPT) which allowed for

preliminary characterisation of the upper 4m of soil from a ground engineering

perspective. The engineering specifications of HS2 allow for only 4mm of vertical

deflection during operation, it is therefore imperative that all efforts be made to

identify areas where displacement greater than this threshold could arise. The data

from the site implies the presence of potentially problematic ground, leading the

authors to propose extensive further investigation prior to construction.


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A preliminary Ground Penetrating Radar study of fluvial architectures at

Spireslack, Ayreshire, Scotland

Joseph T Ainsworth ([email protected]), Andrew J. Mitten and Jaime K. Pringle



Ground Penetrating Radar (GPR) is a near-surface geophysical technique, and has

been previously used to obtain 3D sedimentary architectures of both modern and

ancient fluvial successions. Obtaining multiple 2D profiles behind outcrop exposures

should allow 3D architectures to be extracted and then used to create high-resolution

deterministic 3D numerical models.

This research has collected a GPR dataset at Spireslack quarry in Glenbuck,

Ayrshire, Scotland. Spireslack quarry is an ex-open case coal mine and is presently

designated as SCARP (Scottish Carboniferous Research Park), a long term

educational resource exposing Carboniferous geology.

This preliminary study collected 2D profile behind the B1 outcrop face exposing

channelized fluvial features; here the soil was thinnest, giving the best chance of

good signal penetration. A Sensors&Software PulseEKKO™ 100 system was used

to collect both 50 MHz and 100 MHz frequency data, to determine the optimal

equipment, resolution and achievable depth. Data was then processed using

REFLEXW™ v.3 software before being incorporated into Schlumberger PETREL™

software to create a 3D model.

GPR results imaged a fluvial channel and point bar set that had significant di-electric

permittivity contrasts. Penetration depths were ~20 m, depending upon GPR

antenna frequency. A very near-surface, thick limestone bed, dominated the profiles

at the very near surface.

Study implications suggest GPR is promising at this location to allow the capture of

3D sedimentary architectures, although recommendations should be to collect

further data using lower (25 MHz) frequency profiles and where overlying soil has

been removed.


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Figure 1 – First interpretation of Spireslack GPR profile.

postgraduate research symposium - near-surface … · postgraduate research symposium ......

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