Urban Activity Monitoring in Multiple European Cities Using Ambient Seismic Noise

With the continuous growth of urban populations, monitoring human activity in urban areas is increasingly important for social stability, infrastructure management, and sustainable urban development. Conventional approaches for monitoring human activity, such as wearable devices, survey sensor networks, and satellite remote sensing, are often constrained by privacy concerns, data accessibility, or weather conditions (Chen and Xia, 2023). In this context, ambient seismic noise recorded by seismometers has emerged as a promising alternative for monitoring urban activity, offering high temporal resolution and robust, privacy-preserving observations (Lecocq et al., 2020; Poli et al., 2020). We analyze ambient seismic noise recorded at stations across multiple European cities and countries to investigate the relationship between human activity and seismic noise characteristics. The analysis focuses on frequency bands dominated by anthropogenic signals and examines temporal and spatial variations in seismic noise levels. The results demonstrate that urban ambient seismic noise contains rich information related to human activity and exhibits pronounced diurnal and weekly cycles, as well as variability associated with holidays, weather changes, and major societal disruptions such as the COVID-19 pandemic. Our findings indicate that seismic noise analysis can reveal how multiple factors jointly influence the spatiotemporal patterns of human activity in large urban regions. The results demonstrate the efficacy of ambient seismic observations in facilitating near-real-time monitoring of urban dynamics. Such an approach may provide valuable complementary information for governmental agencies and policymakers, supporting dynamic urban management and decision-making from a geophysical perspective.