Applied & Environmental Geophysics
Explore this Section
Keele offers both a single honours Geology BSc degree and also a 4 year undergraduate Masters in Geoscience (MGeo). Students on both of the degree pathways have the chance to carry out a geophysics project for their final year dissertation.
Here are examples of recent projects undertaken by undergraduate students.
Time-lapse microgravity to assess the development of cavities
Forster, T. 2006. The application of Time-lapse microgravity to assess the development of cavities beneath the Trent and Mersey Canal at Northwich, Cheshire, UK. BSc unpublished Thesis, Keele University, 46pp.
A microgravity survey was conducted in the month of March in 2006 along a 600 metre stretch of the Trent and Mersey canal. The site was located at Marston to the north of Northwich in the Cheshire basin an area renowned for salt mining. The aim of the survey was to collect microgravity data over a known anomaly caused by a subsurface cavity. The data would then be combined with two other data sets from the same site collected in 2002 and 2003. This would enable the application of a time-lapse microgravity survey. The aim of this survey was to establish if the cavity had developed over the four year period. The survey is of importance because until recently there were no locks along this stretch of the canal for 40 miles; therefore a breach in the canal caused by subsidence would have therefore put the surrounding area under severe risk from flooding.
The microgravity survey established the presence of a negative gravity anomaly caused by a subsurface void. The source of the anomaly was proposed to be a cavity in the form of a chimney structure propagating up from the roof of the flooded Adelaide mine. The time-lapse microgravity survey established that an increase in the amplitude of the anomaly over time indicated that the cavity had propagated towards the surface and then activity had temporarily ceased.
Geophysical Investigation of a periglacial feature
Chisem, S. 2007. Geophysical Investigation (GPR and Electrical Resistivity Tomography) of a periglacial feature, Llanpumsaint, Carmarthenshire, South Wales. M.Geoscience unpublished Thesis, Keele University, 45pp.
A near-surface geophysical investigation of a relict periglacial ramparted depression has had to criticise the current method of landform identification by geomorphology alone. The ramparted feature is located in Llanpumsaint, Carmarthenshire, South Wales and is approximately 97x105m elongated east-west. The rampart does not exceed 1m in height and encloses a depression harbouring a bog environment, including trees, mosses, sedges and peat.
ERT, GPR and auger interpretations have resulted in identification of the following major surfaces: (1) the contact between the surrounding sediments and the depression fill; (2) the contact between the inorganic depression fill and the organic peat deposits within the depression; (3) dipping features in the rampart. The dipping features are thought to be evidence of lateral growth of the ice core, or mass wasting of material into the depression and down the sides of the rampart.
Combining these results with a further literature review suggests that this periglacial feature may be polygenetic and thus lie on the genetic continuum between a relict hydrostatic pingo and a remnant lithalsa. The implications of this study are that present classification of landforms schemes based on their geomorphology is inaccurate and will lead to a false reconstruction of past climates. This brings into question the identification of many of the similar landforms found not only in South Wales, but all over the UK and even Europe.
Optimum techniques to detect clandestine child graves
Wood, J. 2007. Determining optimum geophysical techniques to detect clandestine child graves. M.Geoscience unpublished Thesis, Keele University, 45pp.
Near-surface geophysical techniques can be applied to forensic investigations to identify unmarked and clandestine graves. For the former, it is widely accepted that Ground Penetrating Radar (GPR) is the most suitable technique. However, in the detection of clandestine graves, GPR’s suitability is less evident and few studies have been carried out on the optimum detection techniques. For this reason, other near-surface geophysical techniques require the assessment of their suitability to ascertain the optimum detection methods.
The project used the creation of a simulated clandestine grave using animal material proportional in mass to that of child remains. The site was surveyed using a range of near-surface geophysical techniques (GPR, bulk ground conductivity/resistivity and magnetics) and the data analysed to ascertain the optimum detection methods. Surveys were also undertaken prior to the grave creation to act as ‘control’ datasets.
Results show bulk ground resistivity and GPR show the best potential to successfully locate a clandestine burial, with resistivity showing particular potential within the first 6 months of burial. Magnetometry and electromagnetic techniques are too sensitive to cultural noise for use in this kind of environment. More research is needed over longer time periods as these may change over time.
Magnetics to locate clandestine burials
Juerges, A. 2008. Evaluating magnetics as a forensic geophysical technique to locate clandestine burials. M.Geoscience unpublished Thesis, Keele University, 45pp.
In a bid to gain a better understanding of clandestine grave dynamics and properly evaluate the effectiveness of forensic geophysical equipment, simulated clandestine burials have been magnetically surveyed (using the FM36, fluxgate magnetometer), resistivity (dipole-dipole) results have also been acquired for comparison. These simulated graves are situated in a variety of depositional environments and soil types using animal material as analogues for human remains. The sites include; (1) Keele University (rural); (2) Staffordshire University (urban) and; (3) Lincoln University (woodland). A fourth geophysical study has also been undertaken at Abbey Hulton, Stoke-on-Trent (urban), over a local medieval monk cemetery to provide an ancient analogue case study. Single surveys have been conducted over sites 2-4, with repeat (time-lapse) surveys at site 1 at monthly intervals, in order to document any anomaly changes in and around the grave that may correspond with decomposition. The sites contain different target types. Leachate fluids from control material on respective sites have also been sampled and tested for conductivity and pH. The local ground temperatures and rainfall data have also been collected to try and relate geophysical results to tissue decomposition and local climate. It is important to characterise each site, to make comparisons and overcome non-uniqueness.
The magnetic technique highlighted possible grave location anomalies with relative success, however, it was inconsistent between survey sites. The resistivity data successfully highlighted grave anomalies supporting the magnetic results.
For optimal use of magnetic techniques in forensic investigations, it is suggested that they are used in areas of low electro/magnetic ‘noise’, such as open rural sites with little or no metallic content in the soil. Resistivity, on the other hand, has been found to be the optimal technique in areas of disturbed soil. However, from this preliminary study and its relative success in archaeological geophysics, it is noted that the use of magnetics is more effective when trying to locate older burials.
High-resolution 3D reservoir models
Wood, J. 2008. Creating High-resolution, 3D reservoir models from un/confined turbidite systems: examples form the Ross Formation, W. Ireland and the Gres d’Annot, SE France. M.Geoscience unpublished Thesis, Keele University, 45pp.
Deep marine turbidite systems, particularly confined systems, are a major petroleum reservoir type and are becoming increasingly important as the so-called ‘easy’ plays begin to run low. Previous studies of outcrop analogues have indicated that models based on 2D seismic data and cores underestimate the producible channelised sandstones and do not provide realistic impressions of channel connectivity. Without accurate models, petroleum extraction companies may make unrealistic predictions for optimum well position and reservoir volume and so decrease their production from such a play.
Highly detailed data has been collected from the Ross Formation, W Ireland and from the Grès d'Annot Formation, SE France in the form of outcrop data. These data sets are compared with one another to assess the affects of unconfined versus confined basins types on the complexity of the channel systems within turbidite deposits. This process is carried out by using outcrop logs that will be converted into digital format to determine the bed thickness and palaeocurrent data for each locality in both sets of data. These digitised logs are used to construct high-resolution 3D models of the turbidite sequences. The 3D models are used to ascertain information on both the channel connectivity’s and the flow barriers created by small-scale facies variations both laterally and vertically throughout the turbidite sequences. A systematic approach is applied to the methodology in order to make it applicable to analogous turbidite outcrops.
Oakley, S. 2008. Examining cadaver decomposition and the forensic analysis of the surrounding soil. BSc unpublished Thesis, Keele University, 22pp.
This study investigated simulated clandestine burial graves for forensic geophysical analysis, and chemical and physical information gained from these studies was interpreted in a forensic context by using this information to infer changes in soil composition due to decomposition events and microorganisms. Over an 18 week period soil samples were collected from animal burial grounds regularly (every 2 weeks) and grounds with same soil type but with no pig material present as a control. These samples were stored and refrigerated then used for analysis. My paper describes the centrifugation and digestion of the soil samples (leachate and control) for ICP-OES analysis. It is reported that elevated levels of 10 elements from 49 analyzed, these being sodium, potassium, calcium, phosphorus, iron, magnesium, manganese, sulphur, strontium, and lanthanum. Each of these elemental concentrations has been investigated over the sampling period, other studies using the same materials were analyzed by GC-MS and FTIR and soil conductivity and pH were also investigated. These information sources yield important geophysical changes which collectively produce information on decomposition stages, and microorganisms present at specific stages. This can be used in a forensic context to establish possible characteristics of chemical changes during decomposition which could be used as for example as a reference guide in estimating times of death, searching for clandestine graves, and other forensic taphonomy studies.
Linking forensic geophysics to soil types
Oldridge, K. 2008. Linking forensic geophysics to soil types. BSc unpublished Thesis, Keele University, 34pp.
The aim of this research project was to establish whether analysis techniques could differentiate ‘grave-soil’ from background soilwater values. It was also tested to see if they could be correlated with changing responses of geophysical anomalies over time which could have important implications in the detection of clandestine burial sites. Contemporary temperature and weather data were obtained, together with pH and conductivity values of the ‘grave’ leachate and background soilwater values.
Results show increasing conductivity levels of grave leachate fluid over time, compared to the background soilwater, with pH levels showing a more complicated picture. As conductivity levels increase, so do the bulk ground resistivity anomaly strength, compared to background values, but the geophysical signal area decreases, which therefore increases the difficulty in location. More research is clearly needed.