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

Abstract

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.