jarðhreyfingu

Jarðhreyfing is a term used to describe the movement and deformation of the Earth’s crust and near-surface. It encompasses a range of natural processes that change the position, shape, thickness, or volume of ground, from large-scale tectonic shifts to local slope movements and soil creep. In Icelandic geology, jarðhreyfing is closely linked to the country’s active tectonics and volcanic activity, as well as to surface processes driven by gravity and ice.

The main types of jarðhreyfing include tectonic movements such as faulting and plate-tectonic motion that offset rocks and crustal blocks; volcanic processes that involve magma movement, inflation or deflation of magma chambers, and caldera formation; and gravitational or mass movements such as landslides, rockfalls, and slow soil creep. Long-term vertical movements, such as isostatic rebound after ice ages, may also contribute to crustal deformation. In addition, hydrological changes, sediment compaction, and human activities like groundwater withdrawal can induce local ground movement.

Measurement and monitoring of jarðhreyfing rely on geophysical and geodetic techniques. Seismographs detect earthquakes and seismic waves; GPS and other GNSS networks measure ground displacement; interferometric synthetic aperture radar (InSAR) and tiltmeters track surface deformation; borehole instruments monitor strain and stress. Data are used for hazard assessment, land-use planning, infrastructure design, and research into crustal dynamics.

Understanding jarðhreyfing is essential for preparing for earthquakes, volcanic eruptions, landslides, and other ground movements, as well as for optimizing the use of geothermal resources and the management of built environments in regions with active crustal dynamics. See also jarðskjálfti (earthquake) and jarðhreyfingar (earth movements) for related concepts.