Two-station Lg wave attenuation tomography in Central-Southwest China

Understanding Lg wave attenuation provides valuable insights into crustal properties such as temperature, partial melting, and fractures, making it a crucial tool for studying crustal material flow in tectonically active regions. Central-southwestern China, encompassing the eastern Tibetan Plateau, Sichuan Basin, Qinling Orogenic Belt, and nearby areas, is a key region for such research due to its complex tectonic activity driven by the collision between the Indian and Eurasian plates. However, many questions remain about the pathways and barriers that influence the eastward migration of crustal material from the Tibetan Plateau. To tackle these challenges, we treat unresolved 3-D structural effects in Lg spectral amplitude as Gaussian-distributed modeling errors. This approach supports our SVD-based inversion method, enabling reliable estimation of crustal attenuation and thorough evaluation of model resolution and reliability. By incorporating site response corrections into the traditional two-station (TS) method and integrating it with reversed two-station (RTS) and reversed two-event (RTE) techniques, we effectively minimized the impact of source and site effects, enhancing the accuracy of attenuation tomography. Utilizing over 34,000 Lg waveforms from 257 crustal earthquakes, we constructed a high-resolution broadband Lg wave attenuation model across a frequency range of 0.05–10.0 Hz. The findings reveal complex attenuation patterns that correlate with regional tectonic and crustal features, offering fresh insights into the pathways and barriers affecting the eastward flow of material from the Tibetan Plateau.