High-Resolution Monitoring of Urban Activities With Nodal Seismometers in the Guangdong-Hong Kong-Macao Greater Bay Area, China

Urban seismology has become an increasingly popular field in recent years. In contrast to traditional monitoring methods, seismic data provides valuable insights into human activities, is less affected by weather conditions and does not raise privacy concerns. This study examines urban seismic noise in the Guangdong-Hong Kong-Macao Greater Bay Area (GBA, China) using an array of over 6,200 geophones covering an area of 60 × 60 km. The spatial distribution of ambient seismic noise reveals considerable heterogeneity in this highly developed urban environment, demonstrating a strong correlation with population density and transportation routes. By employing energy-based seismic spectral analysis techniques, we analyzed the temporal variations in seismic signal energy under different environmental conditions, finding a strong alignment with local human activity patterns. Furthermore, we extracted specific urban activity patterns from high-frequency seismic noise, including vehicle speeds, traffic flow, subway operations, and the movements of trains and ships. Our findings suggest that the high sensitivity of seismic instruments offers unprecedented spatial and temporal resolution. Overall, seismic data hold significant potential for real-time monitoring, aiding government regulatory agencies and policymakers in dynamic monitoring and urban management.