GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 Fig. 1: Microfracture patern in the two wall rocks of the selected pseudotachylyte-bearing fault. a) BSE-FESEM and b) CL-FESEM microimages of the northern wall rock, displaying low damage and preferental subhorizontal orientaton of the microfractures. c) BSE-FESEM and d) CL-FESEM microimages of the southern wall rock, showing instead extreme damage surrounding a pseudotachylyte injecton vein, and a preferental subvertcal strike of the microfractures. All microimages are taken at the boundary pseudotachylyte-wall rock. Note how in BSE-FESEM microimages the microfracture patern is extremely underestmated. pst=pseudotachylyte. Fracture density decreases exponentally from the pseudotachylyte-wall rock contact towards the wall rock. The rock volumes with highest coseismic damage at the contact with the pseudotachylytes are assumed to be representatve of the host-rock damage preceding frictonal meltng along the slip zone (Pitarello et al., 2008). Based on this assumpton, U S is estmated in the range from 0.008 to 1.35 MJ m -2 . Q was estmated from the thickness of the pseudotachylyte vein (Pitarello et al., 2008) to be ∽ 32 MJ m -2 . In the case of the Gole Larghe Fault, numerical