Electroacoustic pulse source for high-resolution seismic explorations

We suggest an electroacoustic pulse source with frequency characteristics, directivity pattern, and energy suitable for high-resolution prospecting on land and underwater. The seismic wave is produced by a high-energy discharge, set in the focus of a parabolic aluminum reflector filled with insulating liquids. The acoustic pulse is transmitted to the soil via a neoprene diaphragm that couples the transducer to the earth. The discharge is primed by a low-energy preliminary spark, via a third electrode between the principal electrodes, which produces the liquid ionization. An important feature of the electroacoustic source is the variation of frequency spectrum of the impulse, by changing electrical parameters such as capacitance and inductance. The directivity pattern can be changed by inching the electrodes up or down with reference to the focus. First field measurements showed better penetration capacity of the seismic wave of the paraboloid in comparison with a traditional mechanical source. This electroacoustic source can be utilized on land, and even more successfully in underwater acoustic prospecting, by providing suitable electric insulation. In this latter application the frequency range is higher than that used for land prospecting.