Flight Experiment Validation of Altitude Measurement Performance of MOSIR on Tianwen-1 Orbiter

The MOSIR (Mars Orbiter Subsurface Investigation Radar) is one of the scientific payloads carried by the Tianwen-1 orbiter. MOSIR conducted a ground experiment in the desert near Dengkou County, northern China, before the launch of the Tianwen-1 satellite. The MOSIR prototype was suspended from a hot air balloon and flew over a flat region at an altitude of 2500–3300 m. This experiment aimed to verify the system performance and data processing. The data collected in subsurface sounding mode is performed range compression, and the altitude measurement data removes invalid data. After processing, the altitude measurement results of two operating modes are analyzed and compared with that of the Global Position System (GPS), which verifies the accuracy of the altitude measurement.

On the use of gravity data in delineating geologic features of interest for geothermal exploration in the Geneva Basin (Switzerland): prospects and limitations

Gravity data retrieved from the Bureau Gravimétrique International and the Gravimetric Atlas of Switzerland have been used to evaluate their applicability as a subsurface investigation tool to assess key geological features in support of the geothermal exploration in the Geneva Basin (GB). In this context, the application of an effective processing workflow able to produce reliable residual gravity anomalies was implemented as a crucial first step to investigate whether and to what level gravity anomalies can be correlated to geologic sources of geothermal interest. This study focusses on the processing workflow applied to publicly available gravity data, including the quantification of the uncertainty. This was then also used for first-order 2D forward gravity modelling. The resulting residual anomalies demonstrate the potential use of gravity investigations for geothermal exploration in sedimentary basins, and also reveal areas of significant, irreparable misfit, which calls for the use of complementary data and 3D subsurface structural knowledge. The results of such investigations will be presented in subsequent studies.

Identification and Mitigation of a Landslide Threatening Four Operating Natural Gas Pipelines

This paper presents a case study of a landslide with the potential to affect four operating high-pressure natural gas pipelines located in the south-central US state of Mississippi. This case study follows a landslide hazard management process: beginning with landslide identification, through pipeline monitoring using strain gauges with an automated early alert system, to detection of landslide movement and its effects on the pipeline, completion of a geotechnical subsurface investigation, conceptual geotechnical mitigation planning, landslide stabilization design and construction, and stress relief excavation. Each step of the landslide hazard management process is described in this case study.

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>

Combination of Hydraulic and Thermal Tracer Tomography in a Heterogeneous Transient Groundwater Model

<p><strong>Abstract: </strong>In recent years, more and more attention has been paid to engineering projects, such as the remediation of contaminated groundwater, the restoration of water quality, and the seepage control of building foundations. For all these projects, detailed knowledge of the spatial distribution of aquifer hydraulic parameters is required. Inversion based tomography can be considered a promising subsurface investigation approach to obtain aquifer characterization with a high spatial resolution. However, single inversion cannot avoid parameter uncertainty and non-uniqueness problems. Combination of different independent inversions can help to reduce these problems. The purpose of this paper is to reconstruct cross-well hydraulic conductivity profiles by jointly using hydraulic tomography and thermal tracer tomography in a heterogeneous transient groundwater model.</p><p>In this study, based on a three-dimensional data set derived from an aquifer analogue outcrop study, a numerical ground water model is set up to simulate a number of short-term hot water injection tests in a tomographical array, and to perform 2D hydraulic tomography based on hydraulic travel time and attenuation inversions. Consequently, the hydraulic conductivity is calculated from the obtained diffusivity and specific storage values. Parallel to this, the temperature breakthrough curves of the active thermal tracers were utilized to reconstruct the cross-well hydraulic conductivity profiles by using travel-time-based thermal tracer tomography. Comparisons between the results and the “true values” of the analog have shown the satisfying accuracy of the subsurface investigation and advantages when using combined tomographical methods.</p>