Seismic Surveys along the Hunndalen–Mjøsbrua Section
NGI has carried out seismic ground investigations along the Hunndalen–Mjøsbrua section in Gjøvik municipality, as part of a project led by Nye Veier. The project forms part of the planning of new infrastructure in the area, and the assignment was carried out under contract for Norconsult.
Asgeir Lysdahl, Tobias Jokisch and Sander Losnedahl doing fieldwork in beautiful surroundings in Gjøvik ( Photo: NGI / Maren Johnsen )
Background and Purpose
The Hunndalen–Mjøsbrua section is part of Nye Veier’s development plans to improve road safety and accessibility in the Gjøvik region. To support the design work, Norconsult engaged NGI to carry out geophysical investigations to map the ground conditions. The purpose of the seismic measurements was to assess the quality of the soil and rock, map the depth to bedrock, and provide a basis for further geotechnical and engineering geological design work.
Deploying STRYDE Nodes™ (Photo: NGI / Maren ( Photo: NGI / Maren Johnsen)
Methodology, Pilot and Participants
NGI’s project manager for the surveys was Sander Losnedahl, who, with broad experience in land and marine geophysics, led the project’s fieldwork and coordination. Tobias Jokisch, Senior Advisor with long experience in applied geophysics and processing, contributed quality assurance and technical support in the field and in post-processing. Asgeir Lysdahl, Senior Engineer with expertise in geophysical testing, blasting and modelling, was responsible for source operations and technical execution. Cletus Blum, geotechnical engineer, contributed practical fieldwork and logistics. Dylan Mikesell, Senior Geophysicist with a PhD in seismology, quality-assured the processing and interpretation as technical expert, ensuring a high professional standard in the data handling.
For the first time, NGI used the STRYDE system, a wireless and flexible seismic system based on small, rugged nodes that can be freely deployed in both urban and rural areas. The nodes acquired high-resolution, high-quality data throughout the fieldwork.
Several types of seismic sources were used, including dynamite for deep, powerful signals; Mjølner, NGI’s in-house developed tracked weight-drop that delivers controlled, repeatable, high-energy impacts and is suited for use along roads and in less demanding terrain; and a sledgehammer where access and safety called for a simpler source.
Mjølner – NGI's home-built sledgehammer monster! ( Photo: NGI / Maren Johnsen)
Asgeir Lysdahl is in charge of the dynamite ( Photo: NGI / Maren Johnsen)
Results and Further Work
The data from the surveys provide valuable insight into the ground conditions along the section and will be used in Norconsult’s further design work for Nye Veier. The results help reduce uncertainty and risk in the planning of the new road and tunnel. NGI thanks Norconsult for a good collaboration throughout the project, and we look forward to further ground investigations in the region.
