Modelling geomagnetically induced currents in midlatitude Central Europe using a thin-sheet approach

Geomagnetically induced currents (GICs) in power systems, which can lead to transformer damage over the short and the long term, are a result of space weather events and geomagnetic variations. For a long time, only high-latitude areas were considered to be at risk from these currents, but recent studies show that considerable GICs also appear in midlatitude and equatorial countries. In this paper, we present initial results from a GIC model using a thin-sheet approach with detailed surface and subsurface conductivity models to compute the induced geoelectric field. The results are compared to measurements of direct currents in a transformer neutral and show very good agreement for short-period variations such as geomagnetic storms. Long-period signals such as quiet-day diurnal variations are not represented accurately, and we examine the cause of this misfit. The modelling of GICs from regionally varying geoelectric fields is discussed and shown to be an important factor contributing to overall model accuracy. We demonstrate that the Austrian power grid is susceptible to large GICs in the range of tens of amperes, particularly from strong geomagnetic variations in the east–west direction

Aerogeophysikalische Daten rund um das Diendorf-Störungssystem

The aerogeophysical dataset contains geomagnetic, electromagnetic and radiometric (Th, U, K) data from five airborne surveys carried out between 1983 and 1997 in the northern part of Lower Austria:Geras (1996, 1997), Pulkau North (1995), Pulkau (1994), Kamptal-Ziersdorf (1983), Krems (1983).The five airborne surveys were conducted with different technical equipment. In 1998, the geomagnetic datasets were combined and reprocessed. The following corrections and reductions have been applied: 1) Normal Field Correction, 2) Heading Error Correction, 3) Reduction to the Pole. In addition, the electromagnetic datasets were also combined and reprocessed. Since reprocessing modern modelling software often includes a reduction to the pole, the magnetic dataset, published here, is corrected, but no reduction-to-the-pole is applied. In 1998 the electromagnetic data sets were also combined and reprocessed. The radiometric data from the five survey sites were combined into one dataset and adjusted to each other in 2009 (using the "levelling" method).The reprocessed data has been reused in two studies: 1) Paoletti et al. (2022) use all five datasets to estimate the location of tectonic faults in 3-dimensional space using software developed at the University of Naples.2) Schattauer et al. (2022) also use all five datasets to test the usability of different GIS tools for rapid interpretation of aerogeophysical data.Detailed description of data acquisition and processing are provided in both mentioned publications and the references therein.Dieser aerogeophysikalische Datensatz beinhaltet geomagnetische, elektromagnetische und radiometrische (Th, U, K) Daten von fünf Helikopterbefliegungen, die zwischen 1983 und 1997 im nördlichen Niederösterreich durchgeführt wurden: Geras (1996, 1997), Pulkau North (1995), Pulkau (1994), Kamptal-Ziersdorf (1983), Krems (1983). Die fünf Aufnahmen erfolgten mit technisch unterschiedlichen Geräten. Daher wurde im Jahr 1998 die einzelnen geomagnetischen Datensätze zusammengefügt und gemeinsam reprozessiert. Folgende Korrekturen und Reduktionen wurden durchgeführt: 1) Normalfeldkorrektur, 2) heading-Fehlerkorrektur, 3) Polreduktion. Da eine Neubearbeitung mit aktueller Modellierungssoftware häufig eine Polreduktion beinhaltet ist hier der korrigierte, aber nicht polreduzierte magnetische Datensatz als Raster publiziert. Auch die elektromagnetischen Datensätze wurden 1998 kombiniert und reprozessiert. Die radiometrischen Daten der fünf Messgebiete wurden 2009 zusammengeführt und aneinander angeglichen (mit der Methode des "Levellings"). Die reprozessierten Daten stehen hier zum Download zur Verfügung und wurden für folgende Studien verwendet:1) Paoletti et al. (2022) verwenden alle fünf Datensätze, um mithilfe von, an der Uni Neapel entwickelter, Software die Lage von tektonischen Störungen im 3-dimensionalen Raum abzuschätzen.2) Schattauer et al. (2022) verwenden ebenso alle fünf Datensätze, um die Anwendung verschiedener GIS-tools für eine schnelle Interpretation von aerogeophysikalischen Daten zu testen.Eine ausführliche Beschreibung der Datenaufnahme und deren Processing sind in beiden Publikationen und den dort erwähnten Referenzen beschrieben.The methods and equipment for acquisition and (re)processing are described in detail in both linked publications (Schattauer et al., 2022, Paoletti et al., 2022) and the references mentioned therein.Die verwendeten Methoden und Ausrüstung für die Aufnahme und für das (Re)processing sind ausführlich in beiden verlinkten Publikationen (Schattauer et al., 2022, Paoletti et al., 2022) sowie in den darin erwähnten Referenzen beschrieben

The Usage of GIS Tools on Vintage Aerogeophysical Data for Simple and Fast Processing with a Focus on Fault Interpretation: An Austrian Case Study

The reuse of vintage datasets which were acquired in the 20th century can pose challenges for modern geophysical modeling due to missing detailed preprocessing information, significant uncertainties, or lack of precise tracking, etc. Nevertheless, they are often the only available datasets in a target region. We explore here the potential of such vintage airborne geophysical datasets (magnetics, AEM, radiometrics) to detect the location and dip direction of geological faults, using a non-modeling interpretation approach based on multiple GIS tools. We apply our approach in a geologically well-known region where four different types of faults are mapped. The applicability of the tools used in this study depend on the geological setting of each fault and is evaluated based on the comparison with geological and—where available—with modeling data. In general, the GIS tools, especially used on a combination of datasets, show reliable results concerning the location and strike of faults, and even seem to be able to predict the dip direction of a fault

Geophysical Study of the Diendorf-Boskovice Fault System (Austria)

We describe here the results of the characterization of subsurface structures in an area of the south-eastern edge of the Bohemian Massif, in Austria by high-resolution geophysical survey techniques and advanced analysis methods of potential fields. The employed methods included potential field multiscale techniques for source-edge location and characterization of sources at depth. Our results confirmed the presence of already known structures: the location of the Diendorf Fault and the Moldanubian Shearzone are clearly recognized in the data at the same location as on the geological maps, even where the Diendorf fault is covered with sediments of the Molasse Basin. In addition, we detected several geological contacts between different rock types in the Bohemian Massif west of the Diendorf Fault. From our results, we were also able to quickly identify and image, without a priori information, previously unknown structures, such as faults with-depth-to-the top of about 500 m and magmatic intrusions about 400 m deep