Subsurface investigation of the Terrace of the Elephants in the Angkor world heritage site using geophysical survey

<p>Geophysical survey methods are widely applied into not only underground water exploration and environmental pollution & civil engineering fields of the ground, but also in the archeological field such as exploration of the historic remains. The electrical resistivity tomography(ERT) and seismic surveys were conducted to determine the distribution of underground around the terrace of the elephants. ERT survey was conducted to investigate the natural geological distribution and artificial ground around the terrace of the elephants and seismic survey was conducted to find out the velocity distribution of the terrace of the elephants. ERT resulted in a difference in the traces of artificial ground composition around natural ground and terrace of the elephants. Geophysical survey could be used to infer the range and purpose of the underground composition of historic remains (KOICA Project Number: 2019-00065).</p>

The Use of Combined Geophysical Survey Methods for Groundwater Investigation in a Typical Basement Complex Terrain: Case Study of Erunmu, Ibadan, Southwest Nigeria

A combined Survey involving the very low frequency electromagnetic (VLF – EM) and Electrical resistivity surveys were carried out in order to appraise the groundwater potential, and locate appropriate positions for sighting boreholes in Erunmu Community, Egbeda local government area, Oyo State, Nigeria. VLF data were obtained along five traverses as the first step in order to locate suitable vertical electrical sounding (VES) stations. Vertical Electrical Soundings using Schlumberger array were thereafter carried out at twenty 20) locations. The integrated interpretation of both data confirms the presence of aquifers, which includes, weathered zone and basement transition/fractures beneath the area, which prior to this investigation have a history of failed boreholes and wells. The resistivity curve types obtained includes H and A which revealed the presence of 3 to 4 subsurface layers consisting of topsoil, the clay, the sandy clay, fractured zone and the highly resistive bedrock. The resulting geo-electric section from the interpretation revealed the Reflection coefficient which ranges from 0.45 – 0.98. The dominated curve type in the area investigated is the H which is typical of basement complex while the A-type is about 20% of the total curves. Hydrogeological, the topsoil is not important because the degree of water saturation in this layer is very low and cannot be utilized for groundwater. The fractured basement layer (which is present in less than 15% of the study area is very relevant in groundwater prospecting; when it is thick enough the layer could support borehole drilling. Areas identified as geological interfaces in the VLF anomaly charts were also confirmed by the interpreted VES data as poor and intermediate zones for groundwater potential in the study area. The significance of this study is such that it will serve as a useful reference for future research efforts in the aspect of basement complex groundwater studies.

Geophysical Surveys at Khirbat Faynan, an Ancient Mound Site in Southern Jordan

Faynan in Jordan contains the largest copper ore resource zone in the southern Levant (Israel, Jordan, Palestinian territories, Lebanon, Syria, and the Sinai Peninsula). Located 50 km southeast of the Dead Sea, it is home to one of the world’s best-preserved ancient mining and metallurgy districts encompassing an area of ca. 400 km2. During the past three decades, archaeologists have carried out numerous excavations and surveys recording hundreds of mines and sites related to metallurgical activities that span the past 10 millennia. Khirbat Faynan (Biblical Punon), is situated in the main Faynan Valley and is the largest (ca. 15 ha) settlement site in the region and has remained unexcavated until 2011. As Jordan’s most southern mound site with indications of widespread ancient architecture, we employed a suite of noninvasive geophysical survey methods to identify areas suitable for excavation. Earlier geophysical surveys were carried out in the Faynan region by our team in the late 1990s when only EMI (electromagnetic induction) proved successful, but with relatively poor resolution. As reported here, by 2011, improvements in data processing software and 3D ERT (electrical resistivity tomography) sampling protocols made it possible to greatly improve the application of noninvasive geophysical surveying in this hyperarid zone.