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Sub-surface structures and site effects extracted from ambient noise in metropolitan Guangzhou, China

Wang, Shuang, Sun, Xinlei, Liu, Lanbo, Zong, Jianye
Engineering geology 2020 v.268 pp. 105526
alluvial plains, models, prediction, sediments, tomography, China
In this paper, ambient noise is used to investigate near-surface structures and site effects in metropolitan Guangzhou. We deployed 94 short period stations across Guangzhou area, and later a dense linear array across the Shougouling Fault (SF). Using more than one month's continuous data, we invert three-dimensional shear wave velocity structures of Guangzhou area via ambient noise tomography. Results show low velocity near the Guangzhou-Conghua Fault (GCF), Shougouling Fault (SF), and beneath the alluvial plain in the south region. Meanwhile, high-velocity anomalies are beneath the mountain area in northeastern region. Moreover, we obtain the sediment thickness and sub-surface shear wave velocity structures around the Shougouling Fault (SF) by horizontal to vertical spectral ratio (HVSR) method. HVSR results show a significant shift in the thickness of the sedimentary layer across the SF. Shear wave velocity derived from HVSR curves has a consistent trend of variation with the sediment thickness. Our results provide a better understanding of sub-surface structures of metropolitan Guangzhou, and can be served as a reference model for geological disaster migration prediction in the city.