Geo risks
Earthquakes are not the only triggers of destructive ground movements. Slope instabilities such as soil liquefaction, rockfalls, landslides, and tsunamis can occur both spontaneously and as a result of seismic activity, threatening people, infrastructure, and cultural heritage. The geo risks group at SED studies these hazards using geophysical measurements, seismic monitoring, numerical modelling, as well as engineering-geological and geotechnical methods. Thanks to advances in geophysical and seismological techniques, such hazards can now be detected and monitored with unprecedented precision This work forms the foundation for a range of advanced approaches to hazard characterisation and monitoring.
Characterising and monitoring instabilities
Advances in passive seismic techniques now make it possible to measure the natural vibration behaviour of slopes and lakeshores, revealing:
- the extent, volume, and condition of the instability
- internal properties such as stiffness, damping, amplification, and vibration polarisation
- changes over time linked to alterations in internal structure
These methods form the basis for identifying optimal monitoring locations for additional sensors (e.g. seismic sensors, GPS, total stations) and support hazard classification.
Continuous observation and early warning
Real-time monitoring enables rapid risk assessment and early detection of slope-failure precursors. The SED monitors several unstable slopes across Switzerland.
- real-time seismic data are processed automatically to identify anomalies and potential failure precursors
- this approach complements conventional methods such as geodetic surveys and visual inspections
- active monitoring sites include Brienz/Brinzauls, Preonzo, permafrost sites like Gemsstock and Greenland, and slow-moving landslides in Heinzenberg, Val Lumnezia, Braunwald, and Montagnon
Automatic detection of mass movements
Not all tremors are caused by earthquakes; some result from explosions, sonic booms, or mass movements such as landslides, rockfalls, or mudslides. The SED uses modern, self-learning algorithms to automatically detect mass movements once they exceed a certain size:
- real-time detection enables faster risk assessments
- events are added to a public database of recorded mass movements in Switzerland, dating back to 2009 and updated regularly
Liquefaction – loss of ground stability
When earthquakes shake water-saturated silts and sands, these materials can lose their strength and, in extreme cases, liquefy, eliminating their load-bearing capacity. Identifying and monitoring these zones helps prevent unexpected ground failures:
- geophysical surveys are used to locate areas at risk of liquefaction
- permanent borehole sensors measure amplification effects and material behaviour under both linear and non-linear conditions
- results guide risk assessment for infrastructure built over potentially unstable ground
Goal: reducing risk nationwide
By combining advanced monitoring, site characterisation, and modelling, the SED enhances hazard assessments, enables earlier warnings, and supports protectives measures for lives, infrastructure, and cultural heritage from mass movements and earthquake-induced hazards.
Rock instability at Brinz/Brinzauls, which partially failed in June 2023. The red triangle indicates the location of the seismic sensor BRIZ2 and a weather station. Right: Changes of the first higher mode resonance of the instability over time, including b) the change of the resonance frequency and c) the change in the polarization. The number of recorded seismic events is given in d).
Dr. Franziska Glüer is leading the geo risks group at the SED.