Seminar by Charlotte Groult (SHOM) – « Seismogenic Landslides in the European Alps and Seismic Risks Assessment of Counter- Blasting Operations along the French Coast »

Recent events, such as the Brienz landslide (June 2023) and the collapse at Piz Scerscen (April 2024),
have highlighted the hazards associated with large mass movements in the European Alps.
Meteorological conditions are known to play a key role in slope stability and their mechanisms have
been documented at local scales. However, the spatial and temporal variability of landslide
occurrence at the regional scale remains poorly understood, largely due to the complexity of
interacting environmental forcings. Seismology provides a unique opportunity to detect rapid mass
movements with precise timing and to retrieve key source parameters such as velocity, acceleration
and volume, while also offering approximate locations, including in remote areas. We designed an
automatic AI-based workflow to build instrumental catalog of seismogenic landslides. We applied it
to seismic data from 849 stations across the European Alps over the 2000-2023 period. The resulting
catalog, comprising approximately 1,000 seismogenic landslides, offers new insights into the spatial
and temporal patterns of landslide activity and their relationship with meteorological drivers.
Beyond natural hazards, seismology also provides valuable tools to investigate human-induced
processes. It is estimated that there are 635,000 underwater explosives from World War II and only
about 20% of these devices have been neutralized so far. Counter-blasting operations are now
conducted regularly and may impact both terrestrial and marine environments. Leveraging seismic
and acoustic data, the MAESTRIA project aims to develop predictive tools to better assess the
environmental effects of these operations and support risk-informed decision-making.