PSI - Issue 78

Fabio Micozzi et al. / Procedia Structural Integrity 78 (2026) 1205–1212

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vulnerability is highlighted by Fig. 2, where two modern buildings and one under construction show damage of the infill limited in the lower levels. This effect may also increase the structure vulnerability as the drift after the infill collapse increase due to the reduction of the stiffness, potentially leading to a soft-floor mechanism.

(a)

(b)

Fig. 1 (a) Modern residential district intersected by the fault. (b) example of damages of the district. (36.47974 36.33537, coordinates of measurement station exhibiting 1m horizontal offset at approximately 700 m distance)

Fig. 2 Modern and under construction residential buildings, highlighting the infill vulnerability and the higher drift at lower levels.

However, in most cases the evidences of the behavior of the structure-fault interaction are not analyzed and no engineering useful information are obtained from these cases. This work tries to fill this gap giving a partial synthesis of the field observations of the reconnaissance mission, with a focus on how surface faulting and ground deformation affected different types of buildings and infrastructure and why different behaviors have been observed. Fig. 3 show a map with the faults, locations of epicenters and faulting mechanism of the earthquake doublets. The reconnaissance mission almost followed the full path of the fault trace as preliminary mapped by the USGS remote sensing analysis (Reitman et al., 2023), as shown by the many field surveys of the fault reported as red segments in the map. The interaction between the various facets of the group made it possible to find the interesting cases of structures directly placed on the fault trace, reported in the figure as Engineering Point of Interest (POI, yellow triangles). It is important to highlight that the cases reported in this paper are rare. The survey documented significant damage to structures in the areas around the fault. Additionally, many nearby structures have already collapsed or been demolished, which complicates efforts to identify the fault trace and determine if other structures reacted differently to fault displacement. However, in more than one case, structures near but not directly on the fault exhibited greater damage, suggesting that being directly above the fault may sometimes result in complex responses that are more favorable than those experienced by nearby structures.