Review of environmental and geological microgravity applications and feasibility of its employment at archaeological sites in israel (original) (raw)
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Proceedings of SAGEEP, USA, 2009
Gravity survey is comparatively rarely applied for searching for hidden ancient targets. It is caused mainly by the small geometric size of the desired archaeological objects and various noises complicating the observed helpful signal. At the same time, developing a modern generation of field gravimetric equipment allows the register microGal (10^{-8}m/s^2) anomalies that offer a new challenge in this direction. Correspondingly, the accuracy of gravity variometers (gradientometers) is also sharply increased. Archaeological targets in Israel have been classified by their density/geometrical characteristics in several groups. It is supposed to apply in archaeological microgravity original methods for terrain relief computing developed earlier to examine ore deposits under mountainous conditions. 3-D modeling and advanced analysis of gravity anomalies have been applied to estimate the desirable gravity anomalies intensity and projected gravimetric grid. The second and third derivatives of gravity potential have been computed to estimate the resolution of derivative graphs from different models. It is underlined that the physical measurement of vertical gravity derivatives in archaeological studies is important and cannot be replaced by any transformation methods. The performed computations indicate that at least microgravity investigations might be successfully applied in 20-25% of archaeological sites in Israel.
EGU Proceedings, 2015
Microgravity investigations are comparatively rarely used for searching of hidden ancient targets (e.g., Eppelbaum, 2013). It is caused mainly by small geometric size of the desired archaeological objects and various types of noise complicating the observed useful signal. At the same time, development of modern generation of field gravimetric equipment allows to register microGal (10^{−8} m/s^2) anomalies that offer a new challenge in this direction. Correspondingly, an accuracy of gravity variometers (gradientometers) is also sharply increased.
Microgravity for detecting cavities in an archaeological site in Sardinia (Italy)
Near Surface Geophysics, 2015
We present a microgravity study over an archaeological site in Sardinia (Italy) subject to local subsidence, which could be correlated with subterranean cavities. Taking into account the local geological conditions and other factors such as topography, the high urbanization of the area, and financial factors, the micro-gravity method was used to determine the presence of voids and whether these voids are correlated with the local subsidence. A complete Bouguer anomaly map was produced with topography corrections with a density of 1.80 g/cm 3. The density used for the corrections was determined in the laboratory on samples of the geological formations from the same area. The gravity anomaly has been further corrected for the effect of massive structures such as walls and isolated blocks. After removing a third-order polynomial regional trend, the residual anomaly shows small but well-identified anomalies of circular shapes with amplitudes between 15 μGal and 40 μGal. The anomalies are spatially well correlated with the local subsidence, and a map of the vertical gradient of the residual field shows peaks located exactly over the small anomalies previously cited. Using two-dimensional qualitative and quantitative modelling, it is possible to assume that the voids are the cause of the anomalies and therefore could be also the cause of the local subsidence. of the subsurface of the area to identify the possible causes or origin of this subsidence and further, if necessary, to take appropriate steps to stabilize the area. Generally speaking, cavities may be natural, such as solution cavities in limestone, dolomite, and evaporites, or man-madelike tunnels, crypts, or mines (Butler 1984). In the area of investigation, subsidence affected the most superficial lithological unit made up of heterogeneous deposits of anthropogenic origin. In the subsident site, the substrate of the aforementioned unit is represented by a formation made up of sandstones more or less cemented and well compacted, alternating with less coherent sandy facies and the place of an aquifer. It should also be noted that empty or partially filled subsurface cavities are present in the archaeological site as shown by a few standard penetration tests (SPTs) not far from the investigated sector carried out before the subsident event. Therefore, the aim of the microgravity survey was to detect potential subsurface cavities or other anomalous conditions that could produce instability in the investigated area. The choice of the micro-gravimetric method was made considering first that the area was highly urbanized and therefore producing electric and electromagnetic noises that disturb the
Identification of Buried Archeological Objects with Radial Derivatives of Micro Gravity Data
Indonesian Physical Review, 2019
The development of recent gravimetric technology allows us to measure gravity anomalies with accuracy of micro Gal. Micro gravity is able to detect very small gravity anomalies such as anomaly due to buried archeological objects below the earth surface. Radial Derivatives of gravity data is used to sharpen anomaly due to lateral changes of density contrast. Horizontal derivatives carried out by previous researchers have some weaknesses, i.e. the loss of derivative values in certain directions and inconsistence values at the source boundary of the same anomaly edge. To solve the horizontal derivative problem, a radial derivative is made. Radial derivative is derivative of gravity anomaly over horizontal distance in the radial direction from a certain point which is considered as the center of anomaly. There are two kind of radial derivative i.e. First Radial Derivative (FRD) and Second Radial Derivative (SRD). Blade Pattern is another way to enrich the ability of SRD to detect bounda...
International Journal of Geophysics, 2013
Microgravity investigations are now recognized as a powerful tool for subsurface imaging and especially for the localization of underground karsts. However numerous natural (geological), technical, and environmental factors interfere with microgravity survey processing and interpretation. One of natural factors that causes the most disturbance in complex geological environments is the influence of regional trends. In the Dead Sea coastal areas the influence of regional trends can exceed residual gravity effects by some tenfold. Many widely applied methods are unable to remove regional trends with sufficient accuracy. We tested number of transformation methods (including computing gravity field derivatives, self-adjusting and adaptive filtering, Fourier series, wavelet, and other procedures) on a 3D model (complicated by randomly distributed noise), and field investigations were carried out in Ghor Al-Haditha (the eastern side of the Dead Sea in Jordan). We show that the most effective methods for regional trend removal (at least for the theoretical and field cases here) are the bilinear saddle and local polynomial regressions. Application of these methods made it possible to detect the anomalous gravity effect from buried targets in the theoretical model and to extract the local gravity anomaly at the Ghor Al-Haditha site. The local anomaly was utilized for 3D gravity modeling to construct a physical-geological model (PGM).
Site characterization and assessment using the microgravity technique: a case history
Near Surface Geophysics, 2006
A microgravity survey was undertaken to investigate the area surrounding the collapse of a riverbank retaining wall. Initial site investigation identified the presence of a void in the immediate area of the collapse. The objective of the geophysical survey was to assess the extent of the identified void and identify any similar features in the surrounding area. Several geophysical techniques were considered but due to the urban environment, the microgravity technique was chosen. Forward modelling using the data from the initial site investigation was undertaken to optimize the survey parameters. The gravity data was processed to the Bouguer anomaly and the terrain effects of the river-channel morphology accounted for. Anomalies identified within the data set have been analysed using the Euler deconvolution method, which has provided estimates of the depth to the top of the anomalous areas. Inversion of the gravity data using the Cordell and Henderson method has provided an image of the 3D extent of the anomalous areas identified. Guided by this information, a secondary invasive site investigation was conducted which confirmed the interpretation of the geophysical results. The combination of a non-invasive geophysical investigation together with selective invasive control has enabled the full subsurface characterization of this site. obtained because the techniques used are non-invasive and in this case can be constrained with borehole information. Using borehole information in combination with geophysical data can greatly improve the 3D validity of the subsurface model. The use of ground-penetrating radar (GPR) was felt unsuitable due to the
Microgravity investigations are now recognized as a powerful tool for subsurface imaging and especially for the localization of underground karsts. However numerous natural (geological), technical, and environmental factors interfere with microgravity survey processing and interpretation. One of natural factors that causes the most disturbance in complex geological environments is the influence of regional trends. In the Dead Sea coastal areas the influence of regional trends can exceed residual gravity effects by some tenfold. Many widely applied methods are unable to remove regional trends with sufficient accuracy. We tested number of transformation methods (including computing gravity field derivatives, self-adjusting and adaptive filtering, Fourier series, wavelet, and other procedures) on a 3D model (complicated by randomly distributed noise), and field investigations were carried out in Ghor Al-Haditha (the eastern side of the Dead Sea in Jordan). We show that the most effective methods for regional trend removal (at least for the theoretical and field cases here) are the bilinear saddle and local polynomial regressions. Application of these methods made it possible to detect the anomalous gravity effect from buried targets in the theoretical model and to extract the local gravity anomaly at the Ghor Al-Haditha site. The local anomaly was utilized for 3D gravity modeling to construct a physical-geological model (PGM).
APPLICATION OF POTENTIAL GEOPHYSICAL FIELDS AT ARCHAEOLOGICAL SITES IN ISRAEL: AN INTRODUCTION
Proceedings of SAGEEP, 2010, 2010
In Israel occur a giant number of archaeological objects of various age, origin and size. Geodynamical active, multi-layered, and geologically variable surrounding media in many cases damages ancient objects and disturbs their physical properties. This calls to application different geophysical methods armed by the modern interpretation technology. Potential geophysical fields (magnetic, gravity, resistivity, self-potential and thermal) are non-expensive, rapid and effective tools for investigation of the most part of archaeological remains. One of the main advantages is that quantitative analysis of these fields may be realized by the use of similar interpretation methodology. Several examples illustrate effective application of potential geophysical methods over some typical archaeological remains in Israel.
Archaeological geophysics in Israel: past, present and future
Advances in Geosciences, 2010
Israel is a country with diverse and rapidly changeable environments where is localized a giant number of archaeological objects of various age, origin and size. The archaeological remains occur in a complex (multi-layered and variable) geological-archaeological media. It is obvious that direct archaeological excavations cannot be employed at all localized and supposed sites taking into account the financial, organizational, ecological and other reasons. Therefore, for delineation of buried archaeological objects, determination their physical-geometrical characteristics and classification, different geophysical methods are widely applied. The number of employed geophysical methodologies is constantly increasing and now Israeli territory may be considered as a peculiar polygon for various geophysical methods testing. The geophysical investigations at archaeological sites in Israel could be tentatively divided on three stages: (1) past [-1990] (e.g.
Archaeological geophysics in arid environments: Examples from Israel
Journal of Arid Environments, 2010
Israel is a country with mostly arid environments where is localized extremely large number of archaeological objects of various age, origin and size. The archaeological remains occur in multi-layered and variable geological-archaeological media. In many cases physical properties of the ancient objects are disturbed by long-term influence of arid conditions. These disturbances strongly complicate interpretation of observed geophysical anomalies since the useful signal/noise ratio is often sufficiently reduced. Another disturbing factors are the influence of uneven topography, oblique polarization (especially, for magnetic field analysis) and industrial-engineering objects of different kinds situating in the vicinity of studied remains. From a rich arsenal of the developed techniques (the most part of them is described in Khesin et al. (1996)) in the paper are presented the methods of advanced quantitative analysis of potential geophysical fields and 3D magnetic field modelling. A brief archaeologicalgeophysical review indicates that in Israeli archaeological sites were applied practically all near-surface geophysical methods: beginning from the paleomagnetic examination and ending by microwave remote sensing. Such a diversity of applied methods and constant accomplishing of geophysical, archaeological and other data stipulate creating of a multi-linkage as between the various geophysical methods, so also with other archaeologically related databases.