Study On 3D Accurate Positioning Method For Seismic Active Faults In Weifang City

Based on the exploring scope and the state of present research, the method of accurate locating the active faults in the city is divided into two categories according to the characteristics of noise background: one is fitting for the urban area with high noise background, the other one is for the area with none noise background. In the area with high noise background, the research of accurate locating method focuses on the shallow high-resolution seismic acquisition technique and the correct imaging technique of the shallow seismic data in the urban zone. The disturbances of strong vibration can be suppressed effectively in Weifang city using vibrating source to produce seismic wave. The method of excitation of seismic wave is put forward and the technique of frequency-scanning and other correlative techniques of data processing are used to avoid the interference of high vibration. The technique of pre-stack depth migration is introduced to process the seismic data of the shallow faults in the city. Good results are achieved. In the research of accurate suburban positioning method for none noise background, the faults are divided into two categories according to their geometric shape and physical features: one is the faults whose two plates are different; the other is the faults whose two plates are similar. The method of accurate positioning the faults is mainly researched into the second type of faults. The method of horizontal resistivity section is advanced and it is suitable for the fault detection. Through the comparison between two methods, horizontal section method is better than vertical section in accurate positioning the faults and feasibility of field construction for transverse faults with low resistivity. The active faults of Weifang city were detected through applying the 2-dimension high-resolution seismic acquisition technique. Then 3-dimension modeling are improved by using 2-dimension discrete data. As a result, the 3-dimension accurate positioning of the active faults in Weifang city has been got.