The modern Swiss geodetic point network was created in 1992. It consists of 220 points throughout the country. Geodetic points are permanently marked by a stone or with a metal peg. Some are hidden under a covered shaft but their coordinates are known. The position of the points is determined to within a few millimetres. The fifth inspection (and thus the sixth measurement) of the geodetic points is taking place at this time.

Surveying data gathered over several years at a certain point (i. e. time series) is valuable. Frequent resurveying ensures the significance and reliability of the collected data. This continuous approach provides data for evaluations and analyses of specific places and regions.

Better Safe than Sorry

With a few exceptions, swisstopo experts have been surveying the same geodetic points for 30 years. These recurring surveys serve to maintain the network. On-site inspections are carried out to ensure all points are intact and on stable terrain. Replacing geodetic points on unstable terrain with new ones in stable terrain nearby ensures that any data collected from them remains reliable.

Hazard Prevention

The results of the repeated surveys are used to create velocity models. These models show how fast Switzerland, or a region thereof, is moving in a certain direction. Within the country, persistent movements of the top layers of the earth’s crust may cause problems. Movements in the earth’s crust in any directions generate tensions. Earthquakes occur when these tensions are released abruptly. Accelerating points are indicative of risks such as landslides.

Everything is in Motion

Movement occurs not only horizontally but also vertically (see map below). The Alps were formed by moving tectonic plates or, more precisely, by the collision of the African and the Eurasian tectonic plates. This process is still ongoing and the Swiss Alps continue to rise to this day, as is indicated by the values measured at geodetic points in the Alps. The Lower Engadine in the very east of the country, is rising the quickest at 1.4 millimetres per year. Nevertheless, due to continuous erosion, the mountains are not becoming any higher while the geodetic points on the valley flanks are rising.

This model illustrates the vertical movements of the country in millimetres per year.

Lateral shifts in Switzerland are very constant. It is highly probable that the geodetic points – and thus the terrain – will continue to move in the same way in the future. However, not all areas of Switzerland are moving at the same speed or in the same direction. The area near Les Haudères at the end of the Val d’Hérens (VS) is moving the quickest at 1 millimetre per year in direction south-west. The Alpine regions generally move faster than the Swiss Plateau.