Research And Application Of The Shallow Seismic Exploration Method With Anti-disturbance High Resolution On Detecting Urban Active Faults

The paper introduces aim and meaning of exploring urban active faults; researches the examples of exploring earthquake active faults at home and abroad. It starts with geological character of active faults. We synthetically discuss various kinds of possible geophysical methods and technology for seismic active fault exploration and compare their advantage and disadvantage. Meanwhile, research of numerous earthquake events at home and abroad shows that tremendous urban earthquake disasters are mostly attributed to earthquakes caused by active faults hidden under metropolitan areas. The exploration of urban active faults is describes as necessary, urgent and feasible. In view of the concept and characteristics of urban active faults and the unfavorable factors of seismic exploration under urban environment, anti-disturbance high resolution rate seismic exploration is cited as an effective geophysical exploration technique for the present-day exploration of urban active faults.The paper bases on research of predecessors, integrates numerous actually earthquake information, and carries through particularly thorough study on strong disturbed background of urban environment, complicated influence of field condition and method of suppressing disturbance. It founds new methods and technique which can heighten resolution rare of seismic exploration and signal-to-noise, and anti-disturbance problem. There are many differences between the seismic exploration of urban active faults and groovy seismic exploration, expect that they have sound wave, surface wave, refraction wave, first arrive wave, diffraction wave, side face wave, multiple wave, and stochastic disturbance wave, and the seismic exploration of urban active faults also has particular outside disturbance. Objectively, requiring anti-disturbance, high-resolution rate seismic exploration, because of characteristic of urban environment and character of urban active faults. Emphases of exploration of urban active faults are to heighten resolution rare of seismic exploration and signal-to-noise, and suppress disturbance. Bases on the simple description of the basic principle of anti-disturbance high-resolution shallow seismic exploration, the date acquisition technique (the sources, the properties of digital seismic instruments, the receive method and conditions, the observation system) and the date processing technique of the urban active faults detecting are discussed emphatically. The thumping source,tamper source,controlled source and the seismic instruments which match with it ,and the method of small group intervals, small offset, much channels, short array length, observation system and high-frequency receivers are applied during the link of date acquisition. For date processing, digital filtering, wavelet length compression, high-accuracy velocity analysis and migration techniques are studied from a viewpoint anti-disturbance and high resolution. A theoretical analysis is carried out with respect to 1-D band-pass digital filtering, 2-D FK filtering, pre-stack spike pulse deconvolution, post-stack spectrum whitening case of the above results in the anti-disturbance high-resolution seismic exploration of urban active faults in Yuyao city is given. At last the problems existing in present-day seismic exploration of urban active faults are analyzed, and future anti-disturbance high-resolution seismic exploration of urban active faults is envisioned.