###### Abstract  
Many urbanised areas of the Apennines, in Italy, have complex soil stratifications. A typical example is the outskirts of the city of L'Aquila, which is founded on highly heterogeneous soil layers and was severely affected by a strong earthquake in 2009. In such conditions, shear wave velocity profiles (V\({}_{\rm S}\)) obtained from in situ tests such as the Seismic Dilatometer Marchetti Test (SDMT) provide reliable analyses of the local seismic response. This article presents the mono-dimensional (1D) and two-dimensional (2D) seismic response analyses conducted to characterise the soil foundation of the hospital complex and adjacent university buildings in L'Aquila before their seismic retrofitting. This study emphasises the importance of accurate soil characterisation prior to repair interventions, especially in deposits where there are V\({}_{\rm S}\) inversions and in the presence of geometrically irregular and large structures. Under these conditions, estimating the motion amplitudes of the deposit's higher modes beyond the fundamental level is essential in accurately characterising the seismic response, especially for buildings where higher structural modes play a significant role. The results show that approximating the V\({}_{\rm S}\) profile with simplified procedures, as proposed by the Italian Building Code of 2018 (equivalent V\({}_{\rm S}\), similar to average), leads to incorrect estimates of seismic action. V\({}_{\rm S}\) profile inversion; coarse-grained soil; SDMT; 1D-2D seismic response analyses +
Footnote †: journal: Applied Sciences  
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However, in more complex morphological and geometric subsurface settings, where 2D effects are important, the influence of the 1D inversion of the V\({}_{\text{S}}\) profile remains a topic for further research [5]. This study contributes to expanding the knowledge in this field by analysing a real case characterised by both morphological complexity and inversions in the shear wave velocity profile. Specifically, the area on the left side of the Aterno River, in the western part of the L'Aquila city basin (Italy), where the hospital and university complexes are located, presents extensive heterometric Quaternary deposits with significant heterogeneity. These conditions, which are widespread throughout the valley of L'Aquila, require detailed seismic site response analyses, not only for the design of structures and infrastructure but also for land use planning. Such deposits consist of fine to coarse calcareous fragments, mostly a few centimetres in size, embedded in a sandy or silty matrix characterised by highly variable cementation. These materials cannot be penetrated using conventional SDMT or SCPTu techniques. Therefore, to obtain Vs profiles, a borehole must be drilled and then backfilled with sand. This procedure was first introduced by [6] and has since been further refined. Following the 2009 earthquake, the need to rapidly reconstruct the hospital imposed very strict time constraints. As a result, SDMT tests were chosen for the accurate subsoil characterisation of the site, as they proved to be both cost-effective and time-efficient. The original contributions of the field experiments provide reliable data to support numerical methodologies applied to a study site characterised by various types of velocity reversals and geometric complexity. The aim of the present work was to investigate the effects of spatial variability in Vs and velocity inversion on the seismic site response of the studied area, based on subsurface model reconstruction. Both 1D and 2D ground response analyses were carried out to assess the influence of Vs inversion on ground shaking, in terms of transfer functions and acceleration response spectra at the ground surface. The numerical results were analysed and compared with theoretical expectations regarding site amplification and fundamental frequencies.