The invention discloses a high-power
extremely low frequency and ultralow frequency artificial source electromagnetic method for geological
prospecting. In the method, a transmitting antenna is arranged in a region with extremely low electric
conductivity; the qualified
apparent resistivity of the region is in the range of 5,000 to 20,000
ohm m and the thickness of a
high resistance layer of the region is in the range of 20 to 30km; the transmitting antenna is an
extremely low frequency or ultralow frequency transmitting antenna, is erected in a low frame mode and has the length of not less than 60km; the transmitting antenna adopts a power grounding standard;
grounding resistance is permanent; the resistance value of the
grounding resistance is not more than 2 ohms; and a feeding
transmitter has the power of not lower than 500kw, the frequency stability superior to 1*10<-8> and the current of 300 to 350A. For the artificial source electromagnetic method, a transmitted
signal has high strength, the amplitude-phase is stable, the
signal-to-
noise ratio, anti-jamming capability, measurement accuracy and efficiency are high, the detection range is wide, measurement is simple and convenient, and conditions are provided for
earthquake prediction, three-dimensional electromagnetic
prospecting and development of an ocean resource detection technology.