The 90-km long Stuoragurra Fault Complex, part of the approximately 4–5-km wide Precambrian Mierojávri–Sværholt Shear Zone, constitutes the Norwegian part of the larger Lapland province of postglacial faults. It consists of three separate fault systems being 6–12 km apart. The faults dip 30–75° to the SE and can be traced to about 500 m depth. Deep seismic profiling shows that the shear zone dips at an angle of about 43° to the southeast and can be traced to about 3 km depth. A total of approximately 80 earthquakes were registered here between 1991 and 2019. Most of them occurred to the southeast of the fault scarps. The maximum moment magnitude was 4.0. The formation of postglacial faults in northern Fennoscandia has previously been associated with the deglaciation of the last inland ice. Dating of fault reactivation reveals, however, a late Holocene age (between around 700 and 4000 a BP). The reverse displacement of around 9 m and fault system lengths of 14 and 21 km of the two southernmost fault systems indicate a moment magnitude of about 7. The results from this study indicate that the expected maximum magnitude of future earthquakes in Fennoscandia is about 7.

Geological investigations in the last decade increased the number of locations with evidence or indications for glacially triggered faulting in northern central and northeastern Europe, i.e. in the countries of Denmark, Germany, Poland, Belarus, Lithuania, Latvia, Estonia and parts of western Russia. These locations are at the periphery, the edge or even outside of the former ice margin. They are summarized in the following sections.

The following sections introduce geological, geodetic and geophysical methods and techniques that specifically help in the identification of glacially induced faults. In addition, a summary of methods for dating of fault (re-)activation is presented, and the forthcoming drilling project into the Pärvie fault is introduced.

This chapter summarizes the book with a focus on the future of glacially triggered faulting research. The concept of glacially triggered faulting is challenged by new results from Fennoscandia documenting several episodes of fault rupture within the past 14,000 years. We speculate that some of these ruptures at known (or potential) glacially induced faults may not be due to glacially triggered faulting but may contain a signature of tectonically driven intraplate seismicity. Glacially triggered faulting cannot be totally ignored though for these episodes, since the ongoing rebound of the lithosphere is continuously increasing glacially induced stresses that can eventually be released under favourable conditions. As those conditions can only be described by a complex 4-dimensional model, simple identification of glacially induced faults is hampered. Precise dating of the younger fault ruptures is especially important to produce the necessary spatiotemporal image. The intended DAFNE drilling and subsequent in situ observations of the Pärvie Fault combined with numerical modelling will contribute to an improved understanding of the fault mechanism.

Postglacial faults in northern Fennoscandia have been investigated through geophysical methods, trenching, and mapping of brittle deformation structures. Very little is known about postglacial faults through direct measurements. A few short, up to 500 m deep, boreholes exist. Plans for a scientific drilling program were initiated in 2010. The drilling target has been identified: The Pärvie Fault system is the longest known postglacial fault in the world and has been proposed to have hosted an M8 earthquake near the end or just after the last glaciation. Further, this fault system is still microseismically active. The drill sites are north of the Arctic Circle, in a sparsely populated area. Existing site survey data, established logistics, and societal relevance through the fault’s proximity to mining and energy operations make this fault system an appropriate target. The International Continental Scientific Drilling Program approved a full drilling proposal in October 2019. This chapter presents an abbreviated version of the approved proposal.

The most prominent fault scarps are found in northern Fennoscandia in the northernmost parts of Norway, Sweden and Finland. In addition, signs of glacially triggered faulting were identified in adjacent Russia. The following chapters give an overview about these faults from their identification until the very recent results that include, among other things, new reactivation dating and revised fault geometries at the surface from laser scanning.

As glacially induced faults are reactivated due to a combination of tectonic and glacially induced isostatic stresses, it is interesting to model the corresponding fault slip with dedicated models. The next chapters introduce first such a modelling approach with a well-established model of glacial isostatic adjustment followed by a review of stresses to be considered in sophisticated future modelling.

Glacially triggered faulting, also called glacially induced faulting or postglacial faulting, describes fault movement caused by a combination of tectonic and glacially induced isostatic stresses. Stresses induced by the advance and retreat of an ice sheet are thought to be released during or after ice melting and reactivate pre-existing faults. The most impressive fault scarps that witness such activity, are found in Northern Europe. It was assumed these features are unique. This view has changed recently as new faults were discovered – even outside the former glaciated area – and fault activity dating showed several phases of reactivation thousands of years after deglaciation ended. This book summarizes the research until the very recent findings. It reviews the theoretic aspects, i.e. the knowledge to understand the presence of glacially induced fault structures, followed by an overview of geological, geophysical, geodetic and geomorphological investigations methods, a summary of all known glacially induced faults worldwide and an outline for modelling of these stresses and faults.

The following chapter summarize findings, suggestions and indications of glacially triggered faulting outside Europe. This concerns formerly and presently glaciated areas in North America and the polar areas on both hemispheres.