Shallow characteristics of Chenghai Fault Zone, Yunnan, China, from ambient noise tomography and horizontal-to-vertical spectral ratio with two dense linear arrays

• DOI: 10.1016/j.tecto.2024.230351
• Publication Date: 2024-05-15T01:36:49Z
• Authors: Xiaona Ma; Wei Yang; Shanhui Xu; Yunpeng Zhang; Weitao Wang; Junhao Song; Chunyu Liu
• Keywords: Ambient noise level

High-resolution imaging of the shallow structure a fault zone contributes valuable information about regional earthquake hazard and tectonic evolution. The Chenghai Fault (CHF), located in eastern margin collision between Indian Eurasia plates, has accumulated significant shear strain hosted several strong earthquakes, but our understanding its remains limited. Therefore, this study, we deploy ~4.3 km ~ 7 long dense linear arrays across Qina Pianjiao segments CHF from October 24 to November 29, 2020. is imaged using ambient noise tomography, which identifies distinct low-velocity zones (LVZs) beneath segments, with widths ~2.0 3.3 depths ~0.7 0.9 km, respectively. These LVZs exhibit wave velocity contrast 25%–50% relative surrounding regions. We also use horizontal-to-vertical spectral ratio (HVSR) method constrain subsurface structure, geometry thickness match well interface HVSR analysis. distribution high- features consistent geology. damage usually on order ~100 m, smaller than result (width 2–3 km). interpret as sedimentary basins controlled by long-term movements evolution processes rather zones. Moreover, notable variations along strike CHF, indicating that factor controlling development basin region.