Satellite A-DInSAR pattern recognition for seismic vulnerability mapping at city scale: insights from the L'Aquila (Italy) case study

L'Aquila downtown (Central Italy) is situated in a highly seismic region, making it susceptible to numerous historical and recent earthquakes. Among these, the earthquake of Mw 6.3 on 6 April 2009, and the one of Mw 6.7 on 2 February 1703, caused severe damage or complete destruction of the majority of buildings in the historical center. An integrated statistical analysis of A-DInSAR and seismic related building damage data is illustrated. By comparing the seismic damage maps from the 2009 and 1703 earthquakes with the A-DInSAR map produced with Cosmo-SkyMed descending orbit images (acquired between 2010 and 2021), a correlation between post-seismic deformations (in terms of average velocity) and building damage intensity has been identified. Furthermore, ground and building velocities have been separately examined, in order to evaluate the impact of building features and reconstruction efforts on ground deformations. The geostatistical analysis revealed a widespread subsidence motion (until -2 mm/year) across the whole study area. Notably, neighboring points did not exhibit consistent deformation velocities, indicating a lack of spatial correlation. Additionally, Cluster Analysis has allowed recognition of recurring subsidence/uplift trends, which, in terms of shape of curve displacement vs. time, appears independent on building damage intensity or reconstruction interventions. Our results pave the way for a novel utilization of long-term series of satellite SAR data in high-risk seismic zones, serving as a valuable tool to map the most susceptible areas and mitigate seismic risk.