EAGE/DGG Workshop on Airborne Geophysics 2015

Based on economic, geoscientific and educational reasons the chair Raw Material and Natural Resource Management of Brandenburg University of Technology Cottbus, Germany decided to develop an airborne investigation system. Due to the demands and restrictions of the chair the decision was made to purchase the VIRUS SW 100, a full composite ultra-light aircraft. Prior to the fabrication all possible and necessary modifications have been discussed with the engineers of the manufacturer resulting in an aircraft build especially for the demands of a multi sensor investigation platform. The actual geoscientific instrumentation comprehends a CsI-y-spectrometer, 2 K-magnetometer and a VLF-EM-receiver with the option of further sensor installations. The actual configuration enables the system to operate for mineral exploration, geological mapping, detection of freshwater resources and brines and different environmental monitoring missions. The results of recently performed test flights imply that the system can be operated according to the industrial standard.

Airborne electromagnetic methods (AEM) have in the last decade undergone immense hardware and software developments. 10 years ago high resolution shallow surveys for geotechnical engineering, aquifer mapping, landslides etc, could only be done by frequency domain methods whereas time domain methods were more suited for deep measurements. Today, the development of the time domain methods has reached a level where the same or even better data from an airborne platform is obtained compared to the best groundbased system. Also, data inversion has changed from being dominated by approximate algorithms to full solutions modelling the complete system characteristics with inversion of thousands of line kilometers of data in one run. These inversions are possible because the algorithms use multithreaded architecture, which efficiently runs on small workstations or severs.

The new German research aircraft HALO was equipped with an ensemble of geodetic-geophysical instrumentation to carry out geoscientific research in the tectonically active region of the Mediterranean. The instrumentation comprised two airborne spring-type gravimeters, scalar and vector magnetometers, GNSS zenith, sideward and nadir antennas, and a Laser altimeter. This HALO flight mission called GEOHALO could be carried out in June 2012. The mission flights took place over Italy and the adjacent seas, comprising seven parallel profiles from north-west to south-east over the Italien peninsula in a height of about 3,500 m with a length of about 1,000 km each and a line spacing of about 40 km. This presentation contains an overview on the challenges to integrate the scientific instrumentation onboard HALO. We discuss the feasibility and the performance of this instrumentation and present preliminary results from the measurements of the gravity field, of GNSS reflectometry, scatterometry and radio occultation, and of laser altimeter distances over the ocean. Altogether, GEOHALO is the first geoscientific mission on the HALO aircraft. Its success was possible only by the joint efforts of the group of German, Swiss and Spanish universities and research institutions, Italian authorities and institutions as well as by the financial and logistic support of the German Research Foundation, the Helmholtz Association of German Research Centers, the German Aerospace Center and further national and international partners.

In this short paper we briefly discuss geophysical results and engineering value from two AEM surveys supporting the geotechnical design of two highway projects in eastern Norway. One project emphasizes on mapping the thickness of glacial sediments and consequently depth to bedrock, while the other project has a focus on estimating shale volume to be expected connected to road cut excavations.

This study presents a semi-automatic sequential hydrogeophysical inversion method for the integration of resistivity data and lithological borehole information into groundwater models in sedimentary areas.

Because of its complex nature and the wide variety of controlling factors, the geological and mineral resource interpretation of remote sensing data requires sophisticated interpretation methods. Artificial neural networks (ANN) offer an unbiased data driven approach, as they are able to “learn” from “examples” (e.g. known sites of mineral occurrences, known geological formations) and subsequently transfer this “knowledge” into a larger area with similar data sets.

In the past, the application of the technology in geo-science was difficult due to its low awareness level and problems to integrate it into geo-data processing algorithms. In this situation, the software advangeo® was created to provide a normal GIS user with a powerful tool to use ANNs for predictive mapping within a standard ESRI ArcGIS environment. Besides this, the approach provides useful data-processing and data-analysis tools that are adjusted to the solution of special problems: geo-hazards and mineral deposits. Among others, there are algorithms for preparation of vector data, vector/raster data transformation, analysis of raster data (incl. geophysical grids) and data processing reliability analysis. The approach is able to add considerable value to existing data. In different case studies ANN’s have shown their capabilities in modelling and prediction of a wide variety of geological, environmental and geo-economic issues: mineral potential mapping, geological mapping, environmental geology, geo-hazard potential mapping. The application of ANN technologies for data interpretation offers important advantages, as they are applicable even if the relationships between the depending variable (e.g. the rock type) and the controlling factors (e.g. remote sensing data) are not really known, they consider many influencing factors, they work with available data, they are comparable quick and easy to use, and they offer both qualitative (where?) and quantitative (where and how many?) predictive features.