Review of the Usefulness of Various Rotational Seismometers with Laboratory Results of Fibre-Optic Ones Tested for Engineering Applications

Abstract

Starting with descriptions of rotational seismology, areas of interest and historical field measurements, the fundamental requirements for rotational seismometers for seismological and engineering application are formulated. On the above basis, a review of all existing rotational seismometers is presented with a description of the principles of their operation as well as possibilities to fulfill formulated requirements. This review includes mechanical, acoustical, electrochemical and optical devices and shows that the last of these types are the most promising. It is shown that optical rotational seismometer based on the ring-laser gyroscope concept is the best for seismological applications, whereas systems based on fiber-optic gyroscopes demonstrate parameters which are also required for engineering applications. Laboratory results of the Fibre-Optic System for Rotational Events & Phenomena Monitoring using a small 1-D shaking table modified to generate rotational excitations are presented. The harmonic and time-history tests demonstrate its usefulness for recording rotational motions with rates up to 0.25 rad/s.

The Fiber-Optic Rotational Seismograph – Laboratory Tests and Field Application

“…This was made on the base of the Earth rotation measurement regards procedure in detail described in our previous paper [18]. Several experimental tests were carried out to confirm FOSREMs' parameters and reliability including experimental uncertainties calculation based on the registration of the rotational component of the Earth at different frequency bandpass [19], recording strong rotation motion with a new set-up using earthquake simulation [10] and other. As an example, in Figure 4 Because determined parameters fulfill all requirements described for rotational seismology [10], that can be concluded, so FOSREM seems to be appropriate for registration of rotational events associated with rotational seismology.…”

“…Nevertheless, rotational sensors used in field application should meet some technical requirements forced by the rotational seismology which one can find in the paper [10]. Additionally, the issue of data relatability is also significant.…”

Innovative Fibre-Optic Rotational Seismograph

“…The obtained value of ARW is in good correlation with theoretical sensitivity of FORS above mentioned. Because determined parameters fulfil all requirements described for rotational seismology [2], that can be concluded so FOSREM is an appropriate for registration of rotational events associated with rotational seismology.…”

“…In spite of growing popularity of the rotational seismology there are still lack of appropriate rotational sensors for its field application also in form of seismograph which contains rotational sensor, data acquisition system with precise sensor localization and precision time monitoring. Nevertheless, rotational sensors used in field application should meet a number of technical requirements forced by rotational seismology which one can find in paper [2].…”

Measurement of Rotational Events in Regions Prone to Seismicity: A Review

“…The general scope of such parameters for a rotational seismometer, which is used for recording signals connected with rotational seismic effects was formulated only 5 years ago in 2012 by [52] as the following four requirements: (1) independently; (2) assures portable size as well as stable work under changing ambient conditions (temperature, humidity, vibration, pressure,…); (3) uses independent power supply that assures autonomous work; and (4) protects measuring rotation rate with an amplitude of the order of 10−7 rad/s at a frequency range between 0.01 and 0.1 Hz. Moreover, (1) the device should be completely insensitive to linear motion or has possibility to measure linear and rotational movements, and the similar requirements were also described for an earthquake engineering area of rotational seismology interest; the first three were the same and only the last one differs in a measuring range containing amplitude up to a few rad/s at a frequency range up to 100 Hz [53].…”