Low-angle normal faults (LANFs) represent a mechanical conundrum, as their orientation with respect to the stress field should preclude them from accommodating significant displacement. Nevertheless, they occur in many areas worldwide, where they play an important role in crustal extension. Additionally, they frequently localize seismic slip, presenting challenges for earthquake hazard studies.
The Kvamshesten detachment (KD) in western Norway is situated at the base of the Kvamshesten basin and marks the upper boundary of the Nordfjord-Sogn detachment zone (NSDZ). The KD contributed significantly to the extension of the Caledonian mountain belt following its collision. Importantly, the KD is considered an analogue to similar LANFs offshore western Norway that currently host seismic activity. Thus, understanding past conditions in onshore LANFs, such as the KD, has implications for assessing present seismic activity and evaluating the hydraulic properties of potential offshore reservoirs for CCS projects.
The main objective of this master’s project is to develop a conceptual model for seismic slip and fluid circulation along the KD. Fieldwork, structural logging, and sampling will be integrated with analytical techniques (scanning electron microscopy –, electron microprobe analysis – EMPA) and, potentially, micromechanical testing and mapping of rock properties (hardness, elastic modulus) using the nano-indentation technique. Detailed microstructural analysis will aim to identify evidence of past earthquakes along the KD, as well as microstructures characteristic of fluctuations in fluid pressure, which may have influenced the slip history of the KD.
