Identification near-field seismic rotational events by fibre-optic rotational seismometer

Abstract

The paper presents new results about identification near-field seismic rotational events by a fibre-optic rotational seismometer. The Sagnac interferometer with 2&sgr; sensitivity equal to 4.27 10^-8 rads^-1 has been used as rotational seismometer, which can detect rotational events in a direct way. The theoretic investigation of obtained results show that such events can be treatment as the seismic rotational waves. The paper presents the experimental results obtained simultaneously by a fibre-optic and a standard rotational seismometers installed in the Ojcow seismic observatory. The main advantage of such an approach is a possibility to recognize the velocity of seismic rotational waves, which is different from the velocities of other seismic waves.