Seismic activity characteristics of the Sichuan-Yunnan region revealed by data fusion

Accurate characterization of regional seismic activity is crucial for assessing earthquake hazards. Seismic activity depends on multiple factors, including tectonic loading, fault geometry and distribution, crustal and mantle structures, local topography, physical properties, and global environmental changes. Human influences, such as reservoir impoundment, enhanced geothermal systems, and shale gas extraction, further complicate these relationships. Establishing an integrated theoretical and methodological framework through data to analyze these natural and anthropogenic factors represents a frontier challenge in contemporary seismology and geodynamics. This study introduces three novel visualization methods for earthquake catalogs, efficiently capturing the complex relationships between magnitude, frequency, seismic origin time, and epicentral location. Utilizing these methods with comprehensive heterogeneous geophysical datasets from the Sichuan-Yunnan region, including over 420,000 earthquake records, 160 three-dimensional active fault datasets, high-resolution topography, Moho depth, community velocity models, and crustal deformation data, the seismic characteristics of the region over the past 50 years were systematically analyzed. Results indicate that: (1) High seismic activity and hazard areas in the Sichuan-Yunnan region are primarily concentrated near deep major faults, block boundaries, and brittle transition zones with distinct low- and high-velocity anomalies, showing clear spatial banding, temporal clustering, and cyclicity; (2) Fault segments such as Longmenshan, Lijiang-Xiaojinhe, and Nujiang-Irawaddy likely facilitate internal material exchange within the Qinghai-Xizang Plateau. Significant crustal thickening in their northwestern sections corresponds with lower seismic activity; (3) Crustal strain varies notably along the Xianshuihe-Anninghe-Zemuhe-Xiaojiang and Longmenshan fault zones, which delineate the boundary between regions of high- and low-velocity ratio anomalies. These zones host the majority of the regional earthquakes, requiring intensified monitoring due to frequent events despite moderate mainshock magnitudes. Overall, the proposed methodology provides a new reference for deepening our understanding of regional seismicity and developing an improved earthquake visualization technique.