Abstract:Twenty-seven deep seismic observation stations are planned for construction in the administrative area of Shanghai to provide a comprehensive observation system of deep earthquakes,and two deep seismic observation stations will be constructed in Zhangjiang,Pudong district,and the Yangtze River farm,Chongming district,in accordance with China's Eleventh Five-Year Plan.The deep well station in Zhangjiang has been completed and has passed the acceptance stage.Ten test items have been installed including a magnetometer;strain gauge;inclinometer;seismometers;pore pressure,temperature,and water temperature instruments;a water meter installation site in a deep well,a surface-installed strong motion seismograph,and a global positioning system (GPS).In addition,the surface is equipped with a pressure gauge,a temperature gauge,and other auxiliary observation tools.In this study,the micro-tremor and dynamic range data of the Zhangjiang surface station and deep well station data are compared and analyzed systematically.We obtained the following preliminary results:The root mean square(RMS)value of background noise in the deep well is smaller in orders of magnitude than that at the surface station.It can accurately record micro-tremors because of only slight disturbances by the external environment.The seismic signals of deep well observation are the most accurate.The dynamic range of measurement stations effectively reflects the instrument's performance indicators to determine the background environment interference level recorded by the maximum dynamic range of the seismic signal.Due to the superposition station environment noise and seismic signal,the instrument is not up to the dynamic range of design and can only achieve an effective dynamic range of measurement.The effective dynamic range of the deep well station exceeds 30%of that of surface stations;therefore,it can produce a broader range of micro-tremors.Range surface frequency is within 0.3~2.5;the deep well station has low-frequency noise and nearly high-frequency at 25Hz.A comparison of deep bench surface stations reveals that environment noise is much smaller,particularly in the low-frequency range.Moreover,with reference to analysis of data from the Shanghai telemetry seismic network of various types of base background noise,the dynamic range of noise at the Zhangjiang comprehensive deep well and those of the Shanghai network deep wells are consistent.Therefore,comprehensive visible data for the deep seismic section is unaffected by the noise integrated system.With the accelerated process of city development,environmental noise will increase;therefore,the deep well seismometer observation method is more reliable than surface seismometer observation.Completed construction of the seismic section of the deep borehole project can provide greater precision and better quality of observation data to further improve the earthquake monitoring capacity of Shanghai.