Investigation of Geology and Hydro-geophysical Features Using Electromagnetic and Vertical Sounding Methods for Abu Zabad Area, Western Kordofan State, Sudan

The geology and hydro-geophysical features can aid in identifying borehole location. The study aims to investigate groundwater aquifers and best location of boreholes in the crystalline basement area of Abu Zabad near El Obeid Southwest, Sudan. The study area is underlain by two aquifers formations from Precambrian age. The oldest units of basement complex of area under investigation consist of metamorphic rocks including gneiss, schist, and quartzite.The geophysical methods electromagnetic (EM) and vertical electrical sounding (VES) surveys showed that best aquifers yield for construction of boreholes are in weathering and fractures formation. The EM results revealed that structural features are significant for groundwater potential and interpretation of the VES data also revealed four geo-electric layers, but generally two distinct lithologic layers, which include Superficial deposit and bedrock-basement respectively. The curves generated from the data revealed H curve and HK curve, and thickness of these layers varies from 15 m to 50 m in the area. The aquifer thickness range from 20 m to 30 m. The study concludes that these techniques are suitable for identifying borehole location in the basement rock in Abu Zabad Area Sudan.

Spatial Practice at Parchman Place

This chapter focuses on spatial practice and social organization at Parchman Place. Geophysical surveys, magnetic gradiometry in particular, revealed burned Mississippian structures on mound summits and residential areas, subsequently confirmed through excavation. Spatial analysis of geophysical features in residential areas indicates that most neighborhoods were organized in courtyard groups around a central plaza. These neighborhoods are interpreted as analogous to the house groups of the Muskogean-speaking descendants of Mississippian people, particularly the Choctaws, Chickasaws, and Creeks. The Mississippian community at Parchman Place is likewise considered analogous to post-Mississippi period towns. Deposition of large quantities of ash and food remains near one of the neighborhoods is interpreted as analogous to the community and world renewal ceremonies of those same Mississippian descendants. Sometime during the early 15th century, one house group removed to a location away from the plaza and built their houses in two rows on either side of a path or corridor oriented toward the site’s largest platform mound. Spatial and depositional practice at Parchman Place thus encoded particular ideas about community solidarity and renewal, and social differentiation.

High-resolution seismic tomography of Long Beach, CA using machine learning

We use a machine learning-based tomography method to obtain high-resolution subsurface geophysical structure in Long Beach, CA, from seismic noise recorded on a “large-N” array with 5204 geophones (~13.5 million travel times). This method, called locally sparse travel time tomography (LST) uses unsupervised machine learning to exploit the dense sampling obtained by ambient noise processing on large arrays. Dense sampling permits the LST method to learn directly from the data a dictionary of local, or small-scale, geophysical features. The features are the small scale patterns of Earth structure most relevant to the given tomographic imaging scenario. Using LST, we obtain a high-resolution 1 Hz Rayleigh wave phase speed map of Long Beach. Among the geophysical features shown in the map, the important Silverado aquifer is well isolated relative to previous surface wave tomography studies. Our results show promise for LST in obtaining detailed geophysical structure in travel time tomography studies.