## 1 Possible Risks to Pipelines from Geomagnetic Variations  
Space weather is a serious threat to the regular functioning of satellite and ground-based technological systems. One of the most significant space weather hazards is an electric geomagnetically induced current (GIC) in grounded low-resistance industrial structures--power transmission lines and pipelines. GICs are excited by abrupt changes in the geomagnetic field, i.e., large dB/dt. The most severe geomagnetic disturbances and GICs induced by them in technological systems are observed at auroral latitudes. The actual driver of GIC is the variations in the geoelectric (telluric) field. Modern energy and pipeline systems are large networks with a complex topology that cover vast areas of the Earth's surface, the local geoelectric properties of which can vary by up to five orders of magnitude. The electric conductivity of the Earth's interior ranges from \(\sim\)\(10^{-5}\)-\(10^{-4}\) S/m in crystalline silicate rocks up to \(\sim\)3 S/m in the ocean. However, it is not easy to obtain direct information about geoelectric fields. While variations in the geomagnetic field are monitored by a worldwide network of magnetometers, there are very few regular observations of telluric electric fields. Although the calculation of telluric fields and currents from geomagnetic data is feasible, it requires not only a sufficiently dense network of magnetometers, but also the availability of adequate information on the distribution of electrical conductivity in the Earth. The information about the geoelectric structure of the Earth's interior is scarce. For North America, this information was provided by a continental-scale magnetotelluric (MT) sounding project--EarthScope [1]. Within the framework of this project, an MT survey was carried out on a grid with a distance of 70-100 km between temporary sites, and the corresponding impedance tensors were estimated using these MT data. The impedances of the EarthScope project were further used in [2] for the estimation of the geoelectric field response to a uniform sinusoidally varying geomagnetic field. In a similar way, an array of MT impedance measurements in Alberta (Canada) was used to map the spatial structure of the geoelectric field resulting from a magnetic storm [3]. After the Quebec energy blackout of 1989, it was found that space weather not only creates a giant natural plasma laboratory, but also poses a serious threat to the uninterrupted functioning of space- and ground-based technological systems. Nowadays, research is being actively carried out worldwide on the influence of GIC on ground-based technological systems and possible measures to reduce the negative consequences. A negative impact of GICs on power transmission lines and high-voltage transformers is a thoroughly studied phenomenon (see review [4]). At the same time, there is very little scientific information on the impact of geomagnetic disturbances and associated telluric field variations on pipelines. The development of GIC in pipelines results in an increased corrosion at grounding points or at points with insulation damage, as well as disruption in the operation of cathodic protection. Commonly, the cathodic protection against electrocorrosion feeds a negative potential of ~1-2 V between the pipe and soil. Perturbations in the geomagnetic field induce fluctuations in the pipe-to-soil potential (PSP), which take the pipeline voltage beyond the safe range of electrocorrosion protection. During geomagnetic storm/substorms, changes in PSP can be large enough to expose pipeline sections for extended periods of time. For example, on a pipeline in Quebec (Canada), corrosion damage of a pipeline section developed after 5 years of operation only instead of the expected 20-30 years [5]. The extensive studies of the effect of space weather on pipelines were carried out on the Finnish gas pipeline [6,7].