title: Fibre optic system for monitoring rotational seismic phenomena.
abstract: We outline the development and the application in a field test of the Autonomous Fibre-Optic Rotational Seismograph (AFORS), which utilizes the Sagnac effect for a direct measurement of the seismic-origin rotations of the ground. The main advantage of AFORS is its complete insensitivity to linear motions, as well as a direct measurement of rotational components emitted during seismic events. The presented system contains a special autonomous signal processing unit which optimizes its operation for the measurement of rotation motions, whereas the applied telemetric system based on the Internet allows for an AFORS remote control. The laboratory investigation of such two devices indicated that they keep an accuracy of no less than 5.1 × 10(-9) to 5.5 × 10(-8) rad/s in the detection frequency band from 0.83~106.15 Hz and protect linear changes of sensitivity in the above bandpass. Some experimental results of an AFORS-1 application for a continuous monitoring of the rotational events in the Książ (Poland) seismological observatory are also presented.
authors.affiliation: Institute of Applied Physics, Military University of Technology, 2 Gen. Sylwestra Kaliskiego St., 00-908 Warsaw, Poland. akurzych@wat.edu.pl.
authors.forename: Anna
authors.initials: A
authors.lastname: Kurzych
authors.affiliation: Institute of Applied Physics, Military University of Technology, 2 Gen. Sylwestra Kaliskiego St., 00-908 Warsaw, Poland. jarosz@wat.edu.pl.
authors.forename: Leszek R
authors.initials: LR
authors.lastname: Jaroszewicz
authors.affiliation: Institute of Applied Physics, Military University of Technology, 2 Gen. Sylwestra Kaliskiego St., 00-908 Warsaw, Poland. zkrajewski@wat.edu.pl.
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Krajewski
authors.affiliation: Institute of Geophysics, Polish Academy of Sciences, 64 Księcia Janusza St., 01-452 Warsaw, Poland. kt@igf.edu.pl.
authors.forename: Krzysztof P
authors.initials: KP
authors.lastname: Teisseyre
authors.affiliation: m-Soft Ltd., 9-4 Sotta St., 02-790 Warsaw, Poland. jkk@m-soft.pl.
authors.forename: Jerzy K
authors.initials: JK
authors.lastname: Kowalski