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Geophysical Investigation (geophysical + investigation)

Distribution by Scientific Domains

Earth and Environmental Science	92%

Selected Abstracts

Geophysical Investigation at the Falling Creek Ironworks, an Early Industrial Site in Virginia

ARCHAEOLOGICAL PROSPECTION, Issue 4 2001
Geoffrey Jones
Abstract A geophysical investigation was conducted at the site of the Falling Creek Ironworks (1619,1622), the first iron production facility in North America. Electrical resistance and magnetic field gradient surveys were conducted over the site of the seventeenth century ironworks. Additionally, ground-penetrating radar was used to investigate areas under an existing roadway. Linear and rectangular anomalies that appear in the resistance data may be caused by architectural features, possibly shops or domestic structures associated with the ironworks. Several low-amplitude magnetic anomalies that appear in the data appear to be cultural in origin, and may be caused by features associated with the ironworks. A number of high-amplitude magnetic anomalies appear in the magnetic field gradient data that are thought to be associated with iron production, including extensive slag deposits and the possible location of the blast furnace. Ground-penetrating radar data shows an anomalous reflection in the vicinity of the suspected blast furnace, which is partially beneath the modern roadway. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Geophysical investigation and dynamic modelling of unstable slopes: case-study of Kainama (Kyrgyzstan)

GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2008
G. Danneels
SUMMARY The presence of massive Quaternary loess units at the eastern border of the Fergana Basin (Kyrgyzstan, Central Asia) makes this area particularly prone to the development of catastrophic loess earthflows, causing damages and injuries almost every year. Efficient disaster management requires a good understanding of the main causes of these mass movements, that is, increased groundwater pressure and seismic shaking. This paper focuses on the Kainama earthflow, mainly composed of loess, which occurred in 2004 April. Its high velocity and the long run-out zone caused the destruction of 12 houses and the death of 33 people. In summer 2005, a field survey consisting of geophysical and seismological measurements was carried out along the adjacent slope. By combination and geostatistical analysis of these data, a reliable 3-D model of the geometry and properties of the subsurface layers, as shown in the first part of the paper, was created. The analysis of the seismological data allowed us to point out a correlation between the thickness of the loess cover and the measured resonance frequencies and associated amplification potential. The second part of this paper is focused on the study of the seismic response of the slope by numerical simulations, using a 2-D finite difference code named FLAC. Modelling of the seismic amplification potential along the slope confirmed the results obtained from the seismological survey,strong amplifications at the crest and bottom of the slope where there is a thick loess cover and almost no amplification in the middle part of the slope. Furthermore, dynamic slope stability analyses were conducted to assess the influence of local amplifications and increased groundwater pressures on the slope failure. The results of the dynamic modelling, although preliminary, show that a combination of seismic and hydrologic origin (pore pressure build-up during the seismic shaking) is the most probable scenario responsible for the 2004 failure. [source]

Geophysical investigation of the Environs of Rattin Castle Tower House, County Westmeath, Ireland

ARCHAEOLOGICAL PROSPECTION, Issue 1 2009
T. O'Rourke
Abstract No visible archaeological features are today associated with Rattin Castle Tower House in County Westmeath, Ireland located near the boundary of the Pale, the area around Dublin and adjoining counties where English control prevailed. However, both magnetic and resistance data show that Rattin Castle was surrounded by a substantial bawn wall, which has since been removed. Interpretation of two-dimensional resistivity shows a deep trench at the site of the bawn wall. A small (12 by 16,m) rectangular low-resistance anomaly located outside the northern section of the bawn wall but connected to it, is interpreted as a possible gatehouse providing access to the castle. Less than 20,m from this anomaly, the course of an old military road is delineated by magnetic data but is seen most clearly on the resistance data where it is represented by two parallel low-resistance anomalies 230,m long. This road is possibly older than the castle. Rattin is associated with an extensive network of subrectangular field boundaries and enclosures, most noticeably west of the castle. The presence of the military road, potential gatehouse, substantial bawn wall and geographical location all suggest that Rattin Castle was an important strategic fortification in Ireland. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Geophysical investigation of the site of the former monastic settlement, Clonard, County Meath, Ireland

ARCHAEOLOGICAL PROSPECTION, Issue 1 2006
Paul J. Gibson
Abstract Clonard, in County Meath, Ireland was a major ecclesiastical centre from the early sixth century to the twelfth century and buildings associated with the monastery were in existence until the late eighteenth century. However, today no extant buildings or features associated with the monastery are known. The geophysical investigation undertaken in this project has uncovered many anomalies which may be related to the monastic settlement at Clonard. A significant number of linear anomalies have been detected east of St Finian's church using magnetic gradiometry and twin electrode resistance surveying. Many of these anomalies are probably field boundaries; however, a much greater diversity of geophysical responses is located south and west of St Finian's church. A subsquare enclosure of 60,m sides is adjacent to a 300,m long palaeochannel. A fine network of intersecting low resistance anomalies probably represent former artificial drainage channels. Three large areas associated with anomalous magnetic readings were located which might indicate sites of human activity. In addition, there are four distinct zones which have large concentrations of high resistance values suggesting the presence of walls or buildings. Resistivity and ground-penetrating radar depth slices show that one of these zones has characteristics which indicate the presence of an east,west aligned building approximately 7,m wide in a north,south direction and about 15,m long in an east,west direction. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Three-dimensional inversion of automatic resistivity profiling data

ARCHAEOLOGICAL PROSPECTION, Issue 4 2009
Nikos G. Papadopoulos
Abstract Geophysical investigations through mobile multi-electrode systems, such as the automatic resistivity profiling (ARP) method, can increase the size of the surveyed areas without jeopardizing the spatial resolution of the survey. The representation of the apparent resistivity data in maps corresponding to the different measuring dipoles is sufficient in most routine applications for outlining the buried archaeological structures. In specific cases where a more quantitative interpretation of the apparent resistivity data is demanded, a three-dimensional resistivity inversion can provide the necessary tool for this purpose. This work investigates the possibilities and limitations of the three-dimensional resistivity inversion in processing the ARP data. A three-dimensional finite element smoothness-constrained inversion algorithm was used. The active constraint balancing (ACB) method was also applied in order to enhance the stability and the resolving power of the inversion procedure. Resistivity models that are commonly encountered in archaeological exploration were used to generate synthetic apparent resistivity data using a three-dimensional finite element forward modelling program. Inversion of the synthetic data showed that the maximum investigation depth of the ARP method is comparable to the length of the larger receiving dipole and cannot exceed the 2,2.5,m for the particular ARP device tested in this work. Archaeological structures buried within this depth range can be effectively mapped, while the resolution of the subsurface structures is related to the data acquisition parameters. The inversion algorithm was also used to reconstruct the three-dimensional resistivity distribution from the ARP data set collected from the Andilly archaeological site in France. The results effectively showed that the three-dimensional inversion can act as a complementary tool in acquiring a more quantitative interpretation model of the buried archaeological features. Copyright © 2009 John Wiley & Sons, Ltd. [source]

A survey in the park: Methodological and practical problems associated with geophysical investigation in a late Victorian municipal park

ARCHAEOLOGICAL PROSPECTION, Issue 3 2010
Andrew Parkyn
Abstract The survey of Pudsey Park is a geophysical investigation of a late Victorian municipal park. The aim of the survey was to use geophysical techniques to identify the park's changing designs over a 120 year period. An initial design for the park was located during the desk-based assessment, however, it was unclear how much of the original plan had been implemented. It was suspected that Pudsey Park's design has been simplified over time. The project also aimed to identify a suitable sampling strategy for studying park and garden sites by using high-resolution surveys and multiple probe separations for varying depths of detection during earth resistance survey. It was hoped that multiple electrode separations combined with a high density survey could be used to differentiate the signal responses from the modern park designs and earlier design schemes. The choice of strategy is at a significantly higher resolution than guidelines for geophysical investigations for traditional archaeological features. The survey provided highly detailed but complicated data sets; areas of the park have had several redesigns, often where the modern scheme masks previous designs. A number of ,hard' and ,soft' landscaping features were identified including the foundations of the original bandstand (now replaced) and former flower beds. The 0.25,m probe separation surprisingly produced the most defined data with the greatest level of information due to the increased spatial resolution. The geophysical investigation is the first of its kind to investigate a Victorian municipal park in its entirety. The survey validates the importance of high-resolution survey in the study of parks and gardens and also provides a reference data set for future work where poorer documentation hinders interpretation. The geophysics data, together with the accompanying Geographical Information System database produce a unique and detailed picture of a Victorian park from its inception through 120 years of development. Copyright © 2010 John Wiley & Sons, Ltd. [source]

A geophysical investigation of subsurface structures and Quaternary geology at San Marcos Pueblo, New Mexico

ARCHAEOLOGICAL PROSPECTION, Issue 4 2008
Emily A. Hinz
Abstract San Marcos Pueblo site (LA 98), located in the Galisteo Basin south of Santa Fe, New Mexico, encompasses the remains of 43 identified room blocks, a Spanish mission and 20 middens. As part of ongoing field investigations at San Marcos, students and faculty from the Summer of Applied Geophysical Experience (SAGE) field programme are using multiple geophysical techniques to non-invasively investigate the site. Modelling of the underlying Quaternary stream terrace geology and the detection of subsurface Pueblo-era features were accomplished through the integrated interpretation of data from seismic refraction and reflection, electromagnetic, magnetic and ground-penetrating radar methods. Although to date only a targeted spatially small extent of the site has been explored using these methods, the SAGE field programme has been able detect a variety of anthropogenic structures and debris. The SAGE field programme validated the presence of excavations in the natural stream terrace sequence over areas believed to contain kivas, mapped the geometry of walls over a closed room block, and detected an area of magnetized debris associated with smelting operations. Collectively, the data from the SAGE field programme demonstrate the value of using multiple, complementary, geophysical methods for archaeological prospection. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Complementary integrated geophysical investigation around Al-Zayyan temple, Kharga oasis, Al-Wadi Al-Jadeed (New Valley), Egypt

ARCHAEOLOGICAL PROSPECTION, Issue 3 2005
M. A. Atya
Abstract Qasr Al-Zayyan or Al-Zayyan temple in Al-Kharga oasis is documented as a node in the fortress chain that was built by the Romans to secure Darb Al-Arbain; the slaver's trade caravan route between Asyuit and Sudan. The historical and archaeological background of the temple is very scarce; it has been ascribed to Amenebis and was restored during the reign of Emperor Antoninus AD 138,161. In March 2001, an integrated ground-penetrating radar (GPR) and magnetic survey to the west of the temple showed the possibility of an existing structural complex intersecting the present temple at about 45°. It was interpreted as a multigate structure or a tomb complex. In March 2002, the relative topographic elevations were measured and the surface archaeological features were marked on a map. Also a complementary integrated geophysical survey including electromagnetic, geomagnetic and GPR was conducted along northern and western extensions of, and partially covering, the formerly prospected structure in the survey of 2001. It was designed to verify the structure, to define its extent on both the northern and western sides, and to decide about a possible excavation. The results verified the formerly prospected structure of 2001; some of its particular features have been detected. The structure therefore has been mapped over the surveyed area at the northern and western parts of the 2001 structure and it might extend wider than the surveyed area. The former proposition of a multigate structure becomes stronger because of its general appearance, and the idea of a tomb complex still exists owing to the presence of some depressions thought to be graves. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Geophysical Investigation at the Falling Creek Ironworks, an Early Industrial Site in Virginia

Formation of the complex linear dunes in the central Taklimakan Sand Sea, China

EARTH SURFACE PROCESSES AND LANDFORMS, Issue 6 2004
Xunming Wang
Abstract The formation of the complex linear dunes in the central Taklimakan Sand Sea is discussed based on analyses of wind regimes, sand grain size distributions on the topography of the dunes, and a combination of geomorphic and geophysical investigations into the morphology of the dunes. Complex linear dune formation is shown to have ,ve stages. Analysis clearly shows that under the control of wind regime, sand supply and other factors, the simple linear dunes move sideways while they evolve. This is the main cause for the formation of complex linear dunes in the central Taklimakan Sand Sea. We have not collected enough evidence to show whether the complexity of the complex linear dunes is left over from previous wind regimes or whether the previous wind regimes had different dominant wind directions compared to those of modern winds. The evolutionary processes of complex linear dunes in the region partly support the theory of ,barchan evolution' but do not support the ,roll-vortex' and ,bimodal wind regime' hypotheses. After the complex linear dunes were developed, the local wind regime and the other controls such as sand supply suggest it is possible for them to maintain their linear shape. The evolutionary process discussed is limited to the region indicated in this paper, and may not be applicable to the whole Taklimakan Sand Sea. There are different evolutionary processes in different dune,elds because of variations in the factors that control complex linear dune formation. Copyright © 2004 John Wiley & Sons, Ltd. [source]

TEM-fast small-loop soundings to map underground tunnels and galleries connecting the rock-hewn churches of Lalibela, Ethiopia

GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 5 2005
Gaetano Ranieri
As one of the first attempts to utilize the technique for intrasite archaeological prospection, a series of coincident square-loop TEM-fast geophysical surveys were carried out over the compounds of the largest of the rock-hewn churches of Lalibela,Bete Maryam and Bete Amannuel,in North Ethiopia. Archaeologists have long believed that the different churches within each group were connected by underground tunnels. The aim of this survey was to identify, delineate, and map these underground channels and galleries. A total of 33 sounding surveys were conducted, the majority of which used a 3-m-side square loop. The survey traverses explored around the sides of the churches where underground connections to the other churches are possible. The results of the surveys, which are presented in terms of resistivity and depth pseudosections, clearly depict the presence of anomalies that could be associated with cavities, whose orientation suggests the presence of connecting galleries between the different churches. Whether these cavities were actually connecting galleries with religious implications or designed to be used as drainage paths remains a subject requiring further study involving additional geophysical investigations and physical excavation. © 2005 Wiley Periodicals, Inc. [source]

Permafrost monitoring in the high mountains of Europe: the PACE Project in its global context

PERMAFROST AND PERIGLACIAL PROCESSES, Issue 1 2001
Charles Harris
Abstract This paper introduces the structure and organization of permafrost monitoring within global climate-related monitoring programmes. The five-tiered principle proposed for the Global Hierarchical Observing Strategy (GHOST) is applied to the Global Terrestrial Network for Permafrost (GTN-P) monitoring system, and the European network of mountain permafrost boreholes established by the PACE project is discussed in the context of GTN-P. Borehole design and standard PACE instrumentation are described and some preliminary data from selected boreholes are presented. The broader research aims of the PACE programme include geophysical investigations, mapping and GIS strategies, numerical distribution modelling, physical modelling of thaw-related slope processes and mountain permafrost hazard assessment. Copyright © 2001 John Wiley & Sons, Ltd. RÉSUMÉ Le présent article décrit la structure et l'organisation du programme de surveillance du pergélisol et son intégration dans les programmes de surveillance du climat. Le principe à 5 niveaux proposé pour la stratégie d'observation hiérarchique (GHOST) est appliquée au réseau global de surveillance terrestre du pergélisol (GTN-P). Le réseau européen de sondages dans le pergélisol établi par le projet PACE est discuté dans le contexte du GTN-P. La localisation des sondages et l'instrumentation standard de PACE sont décrites et quelques données préliminaires de certains sondages sélectionnés sont présentées. Les recherches du programme PACE comprennent des recherches géophysiques, des stratégies de cartographie et de systèmes d'information géographique, des modèles de distribution numérique, des modèles physiques des processus de versants en relation avec le dégel et enfin des estimations des risques liés au pergélisol de montagne. Copyright © 2001 John Wiley & Sons, Ltd. [source]