Krzysztof P. Teisseyre

Fracture-Band Geometry and Rotation Energy Release

The fracture processes are determined by stress load and local stress concentrations due to accumulation of dislocations and partial mutual dislocation annihilations. In such processes, the formation of dislocation arrays and microcracks related to the premonitory processes and its rebound event plays an essential role. Additional counterpart of stress moments appears due to the antisymmetric stresses related grain rotations and due to stress moments formed by the fracturing pattern.

Fibre Optic System for Monitoring Rotational Seismic Phenomena

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.

FOSREM: Fibre-Optic System for Rotational Events and Phenomena Monitoring: Construction, Investigation and Area of Application

This paper reviews our expertise with construction, investigation and simulation of the fibre optic interferometric device named FOSREM (Fibre-Optic System for Rotational Events and Phenomena Monitoring). The presented device was designed for a direct monitoring of rotational components emitted during seismic events as well as existing in irregular and complex structures. The construction of the FOSREM utilizes the Sagnac fibre interferometer in a minimum optical gyro configuration. This approach causes that FOSREM is complete insensitivity to linear motions, and it enables to measure directly the rotational components. In order to make FOSREM mobile and autonomous device we were focused on decreasing size to the 36 × 36 × 16 cm dimension and implementing special FORS – Telemetric Server which enables to control FOSREM remotely via Internet. The laboratory investigation of our system indicated that it keeps the theoretical sensitivity equal to 2·10−8 rad/s/Hz1/2 and accuracy no less than 6·10−9–5·10−5 rad/s in a frequency band from 0 Hz to the upper frequency between 2.56 and 328.12 Hz, respectively. FOSREM protects linear changes of sensitivity in the above detection frequency bandpass and has the maximum values of rotation rate possible to record without “overshoot” equal to 10 rad/s due to an innovative electronic system.

On the Roots of the Institute of Geophysics, Polish Academy of Sciences

The Institute of Geophysics, Polish Academy of Sciences, established in 1952, continues the long tradition of geophysical research done by the Poles in the past. The ample history of geophysical sciences, predominantly associated with academic centers in Krakow (Cracow), Lwow (Lviv), Warszawa (Warsaw), and also Wilno (Vilnius) and Poznan, is briefly outlined. The world’s first Chair of Geophysics was established at the Jagiellonian University in Krakow in 1895 by Prof. Maurycy P. Rudzki. Various geophysical observatories and stations are mentioned, some of them having roots in the 19th century.

Phase-Shifted Fields: Some Experimental Evidence

We present a comparison between some experimental results on the interaction and synchronization of mechanical and electric fields; such a synchronization may appear with the phase delay by π/2, as shown in recent theoretical results. The solutions related to such a phase-shifted synchronization between some fields follow from the Asymmetric Continuum Theory. This theory concerns not only the mechanical fields, strains and rotations, but also other physical fields entering into interaction with stresses.

Seismology and Earth Dynamics: A Variety of Scientific Approaches

Seismology and related fields were among the basic disciplines constituting the Institute of Geophysics, Polish Academy of Sciences, from its inception. During 60 years, various experimental and theoretical researches have been conducted, and a network of seismic observatories has been managed and gradually updated, as part of international network. Novel theories of the propagation of seismic waves and the processes in the lithosphere and the Earth’s interior, especially in the seismic event preparation areas, have been developed and gradually modified. The statistical studies and profound research on innovative mathematical techniques brought about a real progress in the assessment of seismic hazard and the probability of other extreme events.

Application of the fibre-optic interferometer as a rotational seismograph type AFORS

In this article we show a fibre-optic device based on the Sagnac effect designed for measuring rotational motions which appear during seismic events. The experimental investigations of presented Autonomous Fiber-Optical Rotational Seismographs indicate that such devices keep the accuracy no less than 5.1·10-9 to 5.5·10-8 rad/s in the frequency band from 0.83 Hz to 106.15 Hz. Furthermore, their operations are controlled fully remotely via Internet. We present the comparison of results obtained by such system in the field test with a mechanical rotational seismometer which is mounted simultaneously in the seismological observatory in Książ, Poland.

The Possibility of a Continuous Monitoring of the Horizontal Buildings’ Rotation by the Fibre-Optic Rotational Seismograph AFORS Type

The design and investigation of the Autonomous Fibre-Optic Rotational Seismograph – AFORS as a system used for a continuous monitoring of the horizontal buildings rotation is presented in this chapter. Since AFORS utilizes the Sagnac effect for a direct measurement of rotational components it operates without any reference system designed to work during earthquakes. The presented system contains a special autonomous signal processing unit (ASPU) which optimizes operating of the rotation motions measurement, whereas a newly applied telemetric system based on the Internet (FORS-Telemetric Server) allows for a remote AFORS control. The laboratory investigation of the system named AFORS-2 indicated that with theoretical linear changes of sensitivity it keeps the accuracy no less than \( 4.8{\cdot}10^{-9} \) to \( 6.1 {\cdot} 10^{-8}\ \mbox{rad/s} \) in the frequency band from 0.83 to 106.15 Hz. In our opinion the above results are very optimistic for the future application of AFORS for the continuous monitoring of any rotational moving of the multi-storey buildings as well as the investigation of an in-plane irregularity. The first experimental results of the AFORS-2 operation in a real multi-storey building in Warsaw, Poland are also presented. On this basis the investigation of a new low cost system type AFORS is presented as the chapter conclusion.

Fibre-Optic Sagnac Interferometer as Seismograph for Direct Monitoring of Rotational Events

The possibility of a direct monitoring of rotational events has an important role in the seismological sciences as well as in the applied physics regarding large engineering structures. According to the first aspect, a possibility of existence of the rotational phenomena in the seismic field has been discussed from the beginning of the earthquakes investigations. The interest in these phenomena has been stimulated by strange, rotary and even screw-like deformations that occur after earthquakes, often appearing on parts of tombs and monuments (Ferrari, 2006; Kozak 2006). The classical textbooks on seismology deny the possibility that the rotational phenomena, especially in form of seismic rotational waves – SRW, could pass through a rock, so the earthquake rotational phenomena were explained by an interaction of standard seismic waves with a compound structure of objects they penetrate, which, in fact, might be the case (Teisseyre & Kozak, 2003). Nevertheless, it was theoretically proved that even the SRW could propagate through grained rocks; later on, this possibility was extended on rocks with microstructure or defects (Eringen, 1999; Teisseyre & Boratynski, 2002) or even without any internal structure (Teisseyre, 2005; Teisseyre et al., 2005; Teisseyre & Gorski, 2009), due to the asymmetric stresses in the medium. It should be noticed that the SRW were for the first time effectively recorded in Poland in 1976 (Droste & Teisseyre, 1976). From this time, waves of this type have been studied in a few centers over the world. Taking into consideration large engineering structures, the rotational events monitoring is connected to the torsional effects in structures as well as to the interstory drift. Since the application of new materials and technologies for building constructions, they have irregular structures in-plane which causes difficulties in designing of the horizontal rotations of these structures especially during earthquakes (Schreiber et al., 2009). Recently in the above areas, the first monographs have been published (Teisseyre et al., 2006, 2008; Lee et al., 2009), covering the theoretical aspects of the rotation motion generation and propagation, as well as the examples of the field experiments. A further experimental verification of the existing rotational phenomena in seismic events needs a new approach to the construction of the measuring devices, because the

Spin and Twist Wave Groups in the Seismic Field: A Case of Mining Event

In the theory of rupture and rupture preparation in a medium treated as asymmetric continuum, important role is provided for rotational motions and asymmetric stresses. The rotational motions generate oscillations which propagate in the form of rotational waves, provided that the elastic properties of the medium are asymmetric or the medium consists of loose grains. Therefore, we found it very important to identify the traces of rotational motions which have occurred in the seismic source. Such traces should be present in the recording of the seismic event, and in the seismic noise just preceding it. This work presents results of such a quest in the seismic field generated by an event in Polish Upper Silesian coal mine, and detected at two distant observatories. The rotational components of the seismic field, spin and twist, were detected with rotational seismometers. Then, distinct groups of waves – or pulse sequences – were sought in the curves of both components. Pulses of one component were compared to the other directly and after transformation (phase-shifting and sign reversal), because in the source, the relations between spin and twist motions should include time-lapses which translate into phase-shifting of the generated oscillations. Several time-periods of inter-component conformance just before and during the seismic event were found; these include some conformance episodes between rotational oscillations found at different observatories.