Processes that control permafrost warming in Alpine regions are still not completely understood. Recently, geoelectrical monitoring has emerged as a useful tool to investigate thawing and freezing processes. However, high resistive environments and harsh environmental conditions pose very unfavourable conditions for automated resistivity measurements. Based on the results of several test studies, an improved data acquisition system for geoelectrical monitoring of frozen soils was developed. Furthermore, the implementation of algorithms for statistical analysis of raw data time series led to a significant improvement in the reliability of inversion results. At two Alpine sites, namely Mölltaler Glacier and Magnetköpfl/Kitzsteinhorn, the adapted system was tested at soil temperature conditions between 0°C and -12°C. Data was continuously collected at both locations over nearly a full seasonal cycle. The results showed an almost linear dependency of resistivity and temperature at values above -0.5°C. At lower temperatures, the relation was non-linear, indicating that the reduction of porosity due to the shrinking of connected brine channels was the dominating process that determined the value of resistivity. Based on the derived results, further improvements were suggested, especially for measurements at soil temperatures below -4.5°C as low injection currents make it extremely challenging to gather these. permafrost regions is high priority. The advancement of innovative methods, such as geoelectrical monitoring, allowing all-seasonal, permanent monitoring of remote areas is in demand.The geoelectrical method determines the distribution of the specific electrical resistivity within the subsurface. The specific electrical resistivity mainly depends on porosity, water saturation, conductivity of pore fluid and clay content, and to a minor extent on particle shape and pore geometry. During the process of permafrost thawing and freezing, the volume fraction of the fluid phase (equivalent to a change in porosity), the connectivity of fluid areas and the salinity of the pore fluid is expected to vary. Therefore, geoelectrical monitoring could be an appropriate tool to investigate such processes.

No abstract

Abstract. 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 thinsheet 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 shortperiod 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.

Permanent geoelectrical monitoring, using the GEOMON 4D instrumentation in combination with high resolution displacement monitoring by means of the D.M.S. system, was performed at two active landslide areas: Ampflwang/Hausruck in Austria, and Bagnaschino in Italy. These sites are part of the Austrian geoelectrical monitoring network, which currently comprises six permanently monitored landslides in Europe. Within the observation intervals, several displacement events, triggered by intense precipitation, were monitored and analysed. All of these events were preceded by a decrease of electric resistivity. The application of an innovative 4D inversion algorithm made it possible to investigate the potential processes which led to the triggering of these events. We conclude that resistivity monitoring can significantly help in the investigation of the causes of landslide reactivation. Since the results also contribute to the extrapolation of local displacement monitoring data to a larger scale, resistivity monitoring can definitely support decision-finding in emergencies.techniques, long-term continuous monitoring of deformation and triggering factors and by establishing early-warning systems/centres. The most commonly used early-warning parameters are pore pressure and displacement. However, recent research has shown that other parameters exist, which might give indications of impending triggering before an actual displacement is measurable.The geoelectrical method (direct current DC) has recently been established as a routine geophysical method to investigate subsurface geometry and structural pattern of landslides in Europe (Mauritsch et al.

We present a study of the inneralpine basin of Hopfgarten focused on the analysis of basin fill in order to reveal its formation in relation to paleo-ice flow and tectonics. The study is based on geological mapping as well as seismic (reflection and refraction) and geoelectrical surveys. The oldest sequence in the basin, identified by seismic stratigraphy at 400 m below surface, consists of coarse grained sediments of supposedly Oligocene to Miocene age, which subsided along faults linked to the Inn fault. Three superimposed sequences, each displaying baselaps in contact with a subglacially formed unconformity and sigmoid foresets, show pleniglacial conditions followed by a glaciolacustrine environment. The uppermost of these three sequences lies on top of last glacial maximum till (LGM; Würmian Pleniglacial; MIS 2) and represents Termination I. The middle sequence is classified as Termination II following the Rissian Pleniglacial (MIS 6). The oldest glacial sequence cannot be constrained chronostratigraphically but might correlate with Termination V following the major glaciation of MIS 12. Limited glacial erosion during the LGM occurred only during the ice build-up phase. Further overdeepening was impeded due to topographic barrier and mutual blockades of glaciers within this highly dissected landscape. The occurrence and relative timing of the impediment was controlled by the onset of transfluences and thus by the altitude of coles. The higher amount of overdeepening during older glacial periods is explained by longer phases of free ice advance in the ice build up phase due to higher transfluences routes at that time. Thus, the preservation of older Pleistocene sequences within the basin may be the result of the lowering of watersheds from one glaciation to the next. Our model of an inverse relationship between glacial shaping of the surface and the subsurface may apply to similar Alpine landscapes as well.