Earthquake monitoring and warning
Since 1975 the SED monitors seismic activity in Switzerland with a network of stations equipped with real-time telemetry and centralised data acquisition. The broadband network similar to its present configuration exists since the mid-1990s.
The highly sensitive seismometers record even the slightest shaking, and are able to register vibrations along a broad range of frequencies. These special features allow the group to not only monitor earthquakes on a global and regional level, but also to study the evolution of the Earth and the formation of the Alps, to investigate micro-earthquakes, like those occurring during geothermal activities, and to determine geotechnical characteristics of the subsurface.
The data of the more than 150 broadband and strong motion seismometers are transmitted continually and in real time to the central data center in Zurich. In addition, the SED maintains a pool of mobile stations in collaboration with the Seismology and Geodynamics group under Prof. Domenico Giardini for conducting short-term measurement campaigns and field experiments.
An alert system, maintained and constantly being improved by a team of scientists, technicians and programmers, is now capable of detecting earthquakes and determining their location in less than 30 seconds. In case of an earthquake, the SED informs the public, authorities and media concerning the magnitude, location and possible impacts of an earthquake. In addition, the 24/7 SED on-call service provides information about earthquakes to all interested parties.
There is a need for research into how to further improve such alert systems, in particular regarding early warning systems: electromagnetic waves, as they are used in communications, propagate much faster than seismic waves. Based on this fact, it is currently possible to issue a warning to areas at some distance from the epicenter of the earthquake a few seconds before the strongest shaking, provided the earthquake is detected soon enough. The SED pursues research that aims to optimise this type of early warning system, and investigates whether the magnitude of an earthquake can be determined reliably based on the seismogram output transmitted in the first few seconds of an event.