Lay summary
Earthquake numerical models based on physics of the causative rupture and wave propagation, incorporating conservation laws of continuum mechanics, frictional sliding, and the state of stress in the crust, have expanded our understanding of both source- and propagation-dominated ground motion phenomena. In the present project we propose to develop suite of earthquake source physics-based numerical models to study rupture dynamic complexity and the resulted near-source ground motion, implementing laboratory-based constitutive friction models for different geological structures in the Alpine regions, for the seismological assessment of past and future earthquakes and ground motion prediction in the Alpine regions. Motivated by recent realistic high velocity friction experiments, we plan to use a strongly rate-weakening friction law formulated in a rate-and-state framework. This friction model, not yet studied in realistic geological condition and heterogeneous stress distribution, is a generalized friction model and proven to be a promising model to study earthquake realistically.The Swiss Alps, specifically the Valais area has the largest seismic hazard in Switzerland, has experienced a magnitude 6 or larger event every 100 years, with the last magnitude 6.1 earthquake in 1946 close to Sion and Sierre. Besides this seismic activity, the Valais present rough topography, unstable and steep slopes, deep sediment-filled valleys, wide glacier- and snow-covered areas that potentially increase the seismic risk level due to earthquake-induced natural disaster such as liquefaction, landslides, rock and snow avalanches. In addition, important critical facilities of Switzerland, such as hydroelectric power plants and chemical plants have been built in the Valais, making the region even more vulnerable to damaging earthquake. Considering that the probability of observing a major earthquake (up to magnitude 6.5) in the next 40 years in the region is high, it is wisdom to be prepared to this earthquake. The earthquake physics models developed for this area, will provide a better physical understanding of how earthquakes operate in this area, and consequently it will help to improve our capability for ground motion prediction for the assessment of seismic hazard and to mitigate the seismic risk in the area. Furthermore this site-specific study will contribute to the evaluation of the critical facilities installed in this area, contributing to improved seismic safety of future and existing structures.