NEW LANDSONAR METHOD FOR SURVEY OF GROUND IN BUSY TOWN,KARST CAVES IN MOUNTAIN AND SEA BOTTOM ON WATER

In busy city the geophysical exploration methods are interfered with the noise from vibration of heavy traffic and strong electromagnetic field and stray electricity. An conquering of the interference of rugged landform in mountain land also are the problem of all the geophysical method. Surveying of single karst cave with small or middle sizes is difficult. They are more required to put energy into the new development of technology and new method. Landsonar and its instrument can avoid the interference of noise from vibration of cars and pedestrains with frequency generally less than 300 Hz in city by exciting and receiving elastic waves of 10～4000 Hz. The instrument C-1 can avoid the interference of strong electromagnetic field and stray electricity with supplying narrow frequency alternating current of 11～19 Hz. Because of the zero offset and high and wide frequency band, Landsonar can avoid the interference of landform and have high resolution on single karst cave with small to middle sizes. Because of the especial electrode arrangement, Differential Electric Sounding(DES)method can survey karst cave of 1m high within 100m deep. KS marine acoustics prospecting instrument have better transverse and longitudinal resolution, can distinguish the silt layer, sand layer, cobble layer and riprap layer with thickness more than 1m and geologic structure under sub-bottom, and can work with broken survey line and curve survey line.