Shallow 3D Structure Investigation of Some Cities in the Guangdong–Hong Kong–Macao Greater Bay Area

The Guangdong–Hong Kong–Macao Greater Bay Area (GBA), known as the fourth largest bay area in the world, is a world-class urban agglomeration located on the southeastern coast of China. Littoral fault zones that might trigger strong earthquakes are located offshore of the GBA, making it particularly crucial to pay attention to seismic disasters caused by the site-amplification effect of the strong earthquakes. Therefore, it is essential to determine the fine subsurface structure of the GBA urban agglomeration. In this study, we present the newly collected short-period dense array seismic data in the core urban area of the GBA, which covers a detection area of 60×60  km2 and consists of a backbone observation network and a basic observation network. The backbone observation network included 720 seismic stations spaced 2.25 km apart that recorded continuously for 30–35 days. The basic observation network has a total of 6214 seismic stations that were spaced 0.75 km apart and recorded continuously for 3–10 days. In addition, 63 excitation shots generated by methane detonation source were fired within the observation network. According to the preliminary analysis, the seismic stations recorded both clear active source signals and an abundance of passive source signals, indicating the high quality of the data. The high density of the seismic array and the high-quality seismic data provide important constraints for constructing the shallow fine crustal structure model and the 3D sedimentary thickness model.