A Radically New Principle of Operation Seismic Detector of Nano-Scale Vibrations

A new class broad-band, nano-scale shift position sensor is created and tested. It maybe used as an additional sensor in seismographs/accelerometers/vibrometers. It enables to extend band and enhance sensitivity of the technique available on market by 10-100 times, depending on model of the base product. Combined with such sensor traditional technique may enable to study quasi-static deformations and low-order free oscillations of Earth crust precursor to earthquakes - perhaps unnoticeable to other methods. It may permit to detect also gravity waves, and study peculiarities of tidal motion and tsunami. It may allow to transfer mechanical vibrations of constructions & buildings, with amplitudes over 1 nm, into detectable signal in a frequency range starting from quasi-static movements. It is based on detection of position changes of a vibrating metallic plate placed near the flat coil-being used as a pick-up in a stable tunnel diode oscillator. Frequency of oscillator is used as a detecting parameter, and the measuring effect is determined by a distortion of a MHz-range testing field configuration near the coil by a vibrating plate, leading to magnetic inductance changes of a coil with a resolution ~10 pH. This results in the changes of oscillator frequency. We discuss initial-test data of such position sensor, installed in a Russian SM-3 seismometer, as the additional pick-up component, showing its advantages compared to traditional. We discuss also future of such new position sensor related with substitution of a normal-metallic coil by the superconductive one & replacement of a tunnel diode by S/I/S structure - as less-powered active element in oscillator. These may strongly improve stability of oscillator, and hence, enhance resolution of the seismic detectors.