GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 2.1 GNGTS 2023 Figure 3. Permanent displacement maps were calculated at the “Balsamo range” in San Salvador municipality by: (a) Jibson (2007) and (b) Bray and Travasarous (2007) regression equations. The calculation of several seismic parameters (in particular PGA, PGV, I a ) and the physical - mechanical parameters (effective cohesion c', angle of friction Φ ', weight of the volume unit γ , and the critical acceleration of each slopes k c ), have been accomplished through the method shown by Vessia et al. (2013). Fig. 3 shows the permanent displacements calculated at the Balsamo range located in the Santa Tecla district, in San Salvador municipality. In the maps, the landslides inventoried by Mercurio et al. (2021) triggered by the 13 January 2001 earthquake are reported in black. As can be noted, Bray and Travasarou’s equation shows higher permanent displacement values than Jibson’s one. The crest of the whole Balsamo range shows permanent displacements varying from 20 to 50 cm, between Las Colinas and Los Chorros, that are large enough to trigger landslides. According to Legg et al. (1982), a permanent displacement varying between 5 and 10 cm can cause high damage, while if the values range between 50 to 500 cm the damages will be severe. The values in Fig. 3 show that under the 13 January 2001 earthquake, all along these crests landslides could have occurred.