Geophysical processes taking place several kilometers below Earth’s surface, such as earthquake fault slip, magma accumulation, or pressure changes in reservoirs result in deformation of the surface that can be measured using geodetic methods. Results of such measurements along with geophysical modeling provide vital information about what is going on below the surface.
In the CDI group, we use remote sensing (e.g. InSAR, spaceborne and UAV imagery, bathymetry) and ground-based techniques (GNSS, DGPS) to detect and map ground deformation and we study a range of geophysical processes. Of particular interest are magmatic intrusions at volcanoes, the seismic cycle, and the tectonic processes that drive these.
Volcanic eruptions can threaten life and property, not to mention possible disruptions to airline traffic (over 100000 flights were cancelled in Europe during the 2010 Eyjafjallajökull eruption). Subtle uplift due to increasing magma pressure is usually the first sign that a volcano is entering an active phase, which may culminate in an eruption. We study magma accumulation under volcanoes, dike intrusions, and other volcano-related processes.
Interferometric Synthetic Aperture Radar (InSAR) revolutionized observation capabilities in earth sciences when the first operational radar satellite was launched in 1991. InSAR can provide high-resolution maps of how the Earth’s surface deforms due to sub-surface processes like magma accumulation or pore-pressure changes. This class of geodetic observations is still young and rapidly developing with improved data processing methods and new and more advanced satellite sensors.
Realistic assessment of seismic hazard is important for property planning, choice of building codes, and for the reinsurance industry. Many different types of information can be used in seismic hazard assessments. One key element is measurement and modeling of interseismic deformation, which provides information on how fast stress is accumulating in a fault zone, stress that eventually will get released in a future earthquake.
The earthquake cycle is generally thought to consist of inter-, co-, and post-seismic parts as well as of a nucleation phase. It is important to study all the different parts of the earthquake cycle to advance our knowledge of earthquake physics in general. The main method to study post-seismic relaxation, the recovery processes after major earthquakes, is to measure post-earthquake deformation and use these observations to constrain post-seismic relaxation models.
Large earthquakes cause thousands of casualties annually, but still the earthquake process is not very well understood.
Fluids in the Earth’s crust, such as groundwater, geothermal fluids, oil and gas, play a vital role in society. When pressure decreases in a groundwater aquifer or oil reservoir, e.g. due to pumping, the medium will respond and subsidence will occur. Such cm-scale ground movements can be mapped with satellite radar imaging and the pattern of displacement can provide information about the structure and permeability of the underlying aquifer system or reservoir.
Large earthquakes change the state of stress in the surrounding crust, changing the tendency of future earthquake occurrence.