Abstract: An infrasonic frequency resonant circuit and method for use thereof. An electric power distribution system is employed both as antenna for ISF signals and as a source of inductive reactance for a resonant circuit tuned to a band within the ISF spectrum. A capacitor is placed from the neutral conductor to the ground conductor at an ac power outlet in a structure to form a resonant circuit ordinarily tuned to a band within the ISF spectrum. An ISF spectrum analyzer is connected to the neutral and ground terminals of the resonant circuit to visualize ISF electromagnetic signals induced on the electric power distribution system in both the frequency domain and the time domain and so as to be more readily evaluated.

Abstract: A method and apparatus for sensing one or more physical parameters, including acoustic waves having frequencies from approximately 0 Hz to 15 Hz, electromagnetic waves having frequencies from approximately 0 Hz through 35 Hz and seismic waves having frequencies from approximately 0 Hz through 15 Hz, and detecting precursor seismic activity indicated therein. Acoustic waves are sensed using an infrasonic transducer that produces an electrical signal representative of such waves. Electromagnetic waves are sensed using a suitable antenna, the antenna preferably comprising AC power lines. The antenna produces an electrical signal representative of such waves. Seismic waves are sensed using an accelerometer that produces an electrical signal representative of such waves.