Seismic surveying on land

Applications and Value for Infrastructure Planning

Seismic surveying is a critical tool in the early stages of infrastructure development. By providing detailed information about subsurface conditions, it enables engineers and planners to make informed decisions before construction begins. This can significantly reduce uncertainty and risk, especially in areas with complex geology or limited prior data.

Key applications include:

• Mapping bedrock and sediment layers: Understanding the depth and composition of subsurface layers helps optimize foundation design and avoid costly surprises during excavation.
• Identifying fault zones and unstable ground: Early detection of geohazards such as faults, landslides, or weak zones allows for safer routing of infrastructure and targeted mitigation measures.
• Supporting tunnel and foundation design: Accurate seismic data ensures that tunnels, bridges, and buildings are designed with appropriate support structures, reducing the likelihood of structural issues.
• Monitoring landslides and other geohazards: Seismic methods can be used to track changes over time, supporting long-term safety and maintenance planning.

By investing in seismic surveys early in a project, developers can achieve substantial cost savings through reduced need for reactive measures, optimized design, and fewer delays. NGI’s expertise in adapting seismic methods to urban, mountainous, and Arctic environments ensures reliable results even under challenging conditions.

NGI conducts seismics using different methods

The waves' speed and direction in the ground depending on the mass density. When the waves meet a difference between two different materials, some waves are reflected, some continue, while some follow the interface at high speed (so-called refraction). When the seismic waves reach the surface, they are detected by acoustic sensors (called geophones), and the seismic data is processed and interpreted.

NGI uses three-component digital geophones (wireless and wired) that detect both P- and S-waves and are not affected by electromagnetic noise. The system further allows real-time control of collected data and acoustic noise monitoring. Several different sources can be used, e.g. sweep vibrators or dynamite. NGI has developed a powerful P-wave source that provides up to 4 kJ repeatable strokes with a 160 kg weight.

Several seismic methods exist for different applications, depending on what kind of waves are generated and registered and how these are processed.