A field experiment with self-developed broadband recorders and a preliminary characteristic analysis of the data records

Field experimental studies are mostly conducted from a technological approach, which helps to advance technological improvements in instrumentation and data processing schemes. In combination with a project initiated to explore the deep structures beneath South China led by the Institute of Geology and the Chinese Academy of Geological Sciences, the field experiment in this study was utilised to perform a contrast experiment between the self-developed GEI broadband seismic recorder and the universal Reftek 130 broadband seismic recorder. The power spectral densities (PSDs) and cross-correlation functions of ambient noise observed at ten self-developed broadband seismographs were calculated and analysed. The results obtained through the noise PSDs show the following: (i) strong diurnal variational characteristics of the high-frequency noise PSDs agree well with regular daily human activities, indicating that the high-frequency components of noise are generated by human activities; (ii) the low-frequency noise PSDs from all stations were approximately coincident, and they are believed to be the result of interactions between oceanic waves and continental coastlines; and (iii) strong amplitude asymmetries in the vertical cross-correlation results imply the predominance of noise sources toward the southwest of the deployment. This study may potentially strengthen the mutual promotion of the development of broadband seismographs, the reasonable deployment of broadband seismic stations and the methodology of examining corresponding broadband records.