Restricted by detective equipment and tidal influence seriously, coastal tidal flats are often treated as the transition belt of paralic zone in terms of seismic detection, causing low exploration degree and accuracy in these areas. What is worse, conventional shallow seismic method has a complex system and low acquisition efficiency, which cannot meet the requirements for high-efficiency acquisition in tidal flats. To solve these problems, a towed shallow seismic detection system is specially established for coastal tidal areas, mainly including electric spark source and towable ship-type geophone strings. After comparisons, some advantages of this method are obtained, such as high efficiency, low cost and reliability. Furthermore, its detective accuracy and depth can reach the meter level and more than 800 m, respectively. Then, a series of shallow seismic processing methods are improved for coastal tidal flats. Deconvolution and velocity analysis are emphatically introduced to multiple-wave attenuation. A short array of this towable detection can keep a far more effective wave from being cut off because of its small NMO stretch. Last but not least, the towable method in coastal tidal-flat zones can successfully identify the stratigraphic structure, interface, palaeo-channel, concealed active fault and submarine shallow gas in Jiangsu Coast, Eastern China, which has great practical results and significance for geological and environmental surveys, as well as scientific geo-hazard prevention and mitigation in these areas.

Restricted by the geological exploration equipment and tidal time, the deep seismic detection technology with large offset for exploration of oil and gas resources is often used in the seismic survey of the coastal tidal flats. Furthermore, the coastal tidal flats are only treated as the transition belt of the paralic zone, resulting in the low degree of geological exploration and low detection accuracy, which cannot meet the requirement for high-accuracy exploration in the coastal tidal flats. Conventional shallow seismic exploration technology can detect effectively the bottom interface and internal horizon of the shallow Quaternary system in the coastal tidal flats, but the equipment for data acquisition is complex, and the acquisition efficiency is low, restricting directly the seismic exploration in the coastal tidal flats. Therefore, a shallow high-accuracy seismic detection technology has been developed in this study, which is suitable for the coastal tidal flats. By making full use of the characteristics of the flat terrain in the coastal tidal flats, the method for towed data acquisition has been used, and the seismic detection equipment has been simplified in the tidal flats. With this method, the exploration cost has been reduced, and the data acquisition efficiency has been improved. The detection accuracy can reach the level of meters, and the detection depth is more than 800m with this method. With this technology, the shallow stratigraphic structure and interface in the coastal tidal flats can be detected effectively, and the location of paleochannels, concealed faults and shallow gas can be determined, which support effectively the geological survey of the coastal zone and offshore engineering, being of great practical significance for scientific disaster prevention and mitigation.

For the construction of urban underground space, the shallow stratum structure from surface to 200 meters needs to be high-precision investigated. As limited in the theoretical level, the normal reflection P-wave can’t image in the very shallow subsurface especially in a thick Quaternary area. The SH-wave survey has a higher resolution in the theoretical level because the SH-wave has a lower velocity and shorter wavelength. The aim of this paper is to present a combined seismic reflection survey of P- and SH-wave in a thick Quaternary area where is close to Xiong’an New Area. By using the (λ/4) criterion, we obtain a resolution around 1.4m and 2.4 m for the SH-wave section in 9 m (v=169 m/s and f=30 Hz) and 50 m (v=209 m/s and f=22 Hz) depth separately and a resolution around 3.8m for the P-wave section in 200 meters depth (v=1878 m/s and f=125 Hz).