The GRANDE Array project: temporary seismic network in the Central Apennines

The Central Apennines region (Italy) is regularly affected by seismic activity. In 2009, a Mw 6.1 earthquake occurred close to L’Aquila city. Although the crisis is over, there is still seismic activity in the region (ML<2.8).  To improve our understanding of the structure and dynamics of seismogenic fault zones in Central Apennines, within the GRANDE (hiGh Resolution imAging  of Normal faults Damage zonEs) experiment, we deployed nine dense linear arrays of seismic nodes (157 nodes) crossing two well studied fault damage zones at the surface (Campo Imperatore and Monte Marine fault systems). Previous geophysical and geological surveys precisely characterized these fault damage zones down to a few tens of meters (Fondriest et al., 2020; Cortinovis et al., 2024), but how this fault-related damage extend in depth is yet poorly understood. This temporary network was installed in May 2024, for a one-month period of recording in continue. We used a software using machine-learning to pick, detect and create a preliminary seismic event catalogue. Several tests were realized to check the nature of the event (anthropic or seismic) and the quality of detection. Then, we applied a relocation program to obtain a better location of the events and create a high-quality event catalogue for the one-month recording period. Moreover, we cross-correlated the signal at pairs of stations to retrieve a local tomographic picture of the studied areas. This new and original seismological dataset allow deepening our understanding of the structure of fault damage zones from surface to depth and improve our knowledge about dynamics of large earthquakes rupture, interseismic strain accumulation and release for one of the most hazardous faults in Europe.