New simplified models for earthquake-triggered landslides in large area: application to Italian case studies

Shake maps, produced a few hours after a seismic event, represent the key input for the rapid assessment of earthquake triggered landslides scenario maps in near real time.

The IGAG20 approach (Falcone et al., 2021) improves the prediction of these by contemplating the site effects that are calculated as a function of the V_s30 (Mori, 2020) and the intensity of the shaking.

The method originally calculates the amplification factor for some intensity measures at the surface level for the national hazard, in Italy.

Here, we present applications of the method, in terms of scenarios, for a few main shocks of past seismic events in Italy: Friuli 1976, Umbria-Marche 1997 and L’Aquila 2009. We used the OpenQuake engine (Silva et al., 2014), to produce PGV and PGA stochastic maps including amplification factors. The PGV map helped calculating landslide probability maps within the Nowicki et al. (2018) model, while the PGA map was a key input for landslide rockfall maps obtained within the STONE model (Antonini et al., 2002, Guzzetti et al., 2002; Alvioli 2020).

Results of both models were compared with available landslide records for the corresponding earthquake events, either in the form of points or polygons (Govi 1977; Guzzetti et al 2009).