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1

Spin and twist motions in the earthquake preparation processes: Analysis of records

Teisseyre K.

Acta Geophysica

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2011

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Vol. 59, no. 1

5-28

EN

Three seismic events in L’Aquila region and one in western Greece have been chosen for comparative analysis of two kinds of seismic motions, spin and twist. These torque components of the seismic field were detected in horizontal plane with the rotational seismometers. Homologous parts were sought in the signals of spin and twist components – curve of one component was compared to the other directly and after transformations: phase-shifting and sign reversal. To achieve better clarity, these operations were done on the data divided into several descendant signals with the use of band-pass filtration. Conformities of spin and twist, revealed in this way, are assumed to be results of distant processes in the source, where relations between rotational and shear motions include retardations. The analysis embraced also the time-period preceding an earthquake, and the conformities found here are attributed to phenomena occurring in the focus just before the rupture.

2

A method to minimize errors in seismic differential measurements

Wiszniowski J., Teisseyre K.

Acta Geophysica

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2010

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Vol. 58, no. 4

604-623

EN

The seismic differential signal is measured as a difference between two seismic recordings made by seismometers placed in the same direction close to each other. The purpose of our study was to verify possible inherent errors in the measurement technique, especially in far-field measurements. We present a model of errors resulting from small differences in 3D responses of seismometers. While constructing this model, we singled out two sources of error. These are: the previously known error resulting from differences in seismometer's response, and a component due to motion in transverse direction. The evaluation of errors on the differential signal measurement was made for distances between horizontal seismometers varying from 16 cm to 97 m. A new method to assess the above-mentioned errors in differential signal measurement is proposed. This method is based on estimating a dynamical correlation between the differential and translational signals.

3

Seismic events and rotation waves in the Hans Glacier, Spitsbergen, and the Pasterze Glacier, Austria

Teisseyre K., Górski M., Suchcicki J.

Acta Geophysica Polonica

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2004

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Vol. 52, nr 4

465-476

EN

Methods of recording and data analysis that jointly allow to estimate rotation components in the seismic field were applied at two glaciers: the Hans Glacier in the Spitsbergen archipelago behind the North Polar Circle and the Pasterze Glacier in the Austrian Alps. A substantial content of rotation velocity components was found in the data collected at both locations; especially high rotation amplitudes were found in the Hans Glacier. Differences between the results obtained from these two glaciers are shown and briefly discussed.

4

Time-domain filtering of seismic rotation waves

Nowożyński K., Teisseyre K.

Acta Geophysica Polonica

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2003

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Vol. 51, nr 1

51-61

EN

Rotational parts of seismic waves are extracted from recordings of differential seismic signals. Thus, all differences in responses of the seismometers cause disturbances which obscure these hidden components. The method of removing great part of these disturbances is developed, based on the time-domain filtering and using the data collected over a selected period of seismic monitoring called the test phase. Examples of seismic rotation components for some events registered in the Ojców observatory are shown, together with results of checking the adequacy of the presented method.

5

Seismic rotation waves related to volcanic, mining and seismic events: Near-field and micromorphic motions

Teisseyre R., Teisseyre K., Moriya T., Palangio P.

Acta Geophysica Polonica

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2003

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Vol. 51, nr 4

409-431

EN

Rotation and twist waves recorded in Hokkaido (Japan), Ojców and Książ (Poland) and L'Aquila (Italy) bring a new insinght into the features of these motions for volcanic, mining and tectonic events. The rotation seismograph system used at the observatories in Hokkaido differs from that observatories in Poland and Italy. Nevertheless, the results obtained, for all observatories, are compatible. The levels of rotation and twist motions depend distinctly on the back-ground properties of the recording sited. Moreover, at a given recording station we have noticed two different levels of these motions; for some near events the records indicate very small rotation motions, while for other, also near events, these motions are distinctly greater and remain on a similar level as those for records from the distant sources. For the near events the evident differences in magnitudes and character of these motions suggest a distinct relation between the rotation and twist motions and the source mechanism. Similarly, an analysis of records for the volcanic events indicates existence of two kinds of events: for the first group, the rotation components reach the order of magnitude much greater than those for the group, for which the rotation and twist motions are quite negligible. The records related to this group, representing probably the near-surface volcanic explosions, confirm at the same time the reliability of results obtained for the rotation motions belonging to the first group, as the technique of recording and distances remain for both groups the same. The records from several stations give grounds for searching for as influence local structure on rotation and twist motions. The data treatment applied for local events made it possible to separate the recorded motions into the micromorphic and source related parts.

6

Recording the seismic rotation waves: reliability analysis

Teisseyre R., Suchcicki J., Teisseyre K.

Acta Geophysica Polonica

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2003

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Vol. 51, nr 1

37-50

EN

An estimation of reliability of seismic rotation waves is based on the data collected with the use of rotation horizontal seismographs; each rotation seismograph system consists of two anti-parallel seismographs. The test and working positions of the rotation seismographs enable us to use the filtering procedure in the FFT domain in order to approach the identity of seismograph responses for each system; this procedure is applied for the collected data. Reliability of records of seismic rotation waves is based on the estimated ranges of the mean square values of the errors (test position) and of the rotation and twist components (working position). In this way, we get a proof about the existence of seismic rotation waves, at least those rotation components of seismic waves which originate near the surface and close to the observation site. This proof may be very important for the earthquake engineering problems. The question of a possibility of reducing far-distance rotation effects, as those related to seismic source process, remains open.

7

Earthquake fracture-band theory

Teisseyre R., Teisseyre K., Górski M.

Acta Geophysica Polonica

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2001

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Vol. 49, nr 4

463-479

EN

We present the theory of general structure of fracturing in an earthquake source; this new model is based on generalization of the shear band model presented in pervious papers. These models of the seismic source zone are based on the thermodynamics of line defects. In the thermodynamics of line defects the dislocation superlattice plays an essential role. The concept of line vacancy (vacant dislocation) enables us to construct a superlattice consisting of dislocations and vacant dislocations. The model introduced applies to plastic deformations; stress load increase may lead to some changes in dislocation density related to the superlattice. Such changes can also be related to a change of the number of vacant dislocations or to a change of the superlattice parameter. An increase of the number of dislocations corresponds in this case to a hardening process and is related to the spatial structure of superlattice. A pronounced plastic deformation is realized through the formation of shear bands; the dislocation number becomes multiplied along the shear planes and in consequence exceeds the number prescribed by the superlattice structure which, however, will be perservered in the direction perpendicular to the shear band planes. Our new generalization takes into account the tensile and shear fracturings forming the concurrent processes; however, some phase shifts between them shall be included. Moreover, in this paper the earthquake structure model may be not only related to the microdefect distribution, but also to an existence of macro-defects bound to a fine structure of focal region. This fine structure can be formed by some elements of the fracture space or by a certain distribution of the grains. Properties of such structures are described by the micromorphic theory. Moreover, we will not split, in a heuristic way, the deformations into the elastic and plastic parts, because the plastic phenomena are to some extent included here by the micromorphic or, as one can say, the granular/block structure properties of the medium. Applications for an analysis of earthquakes, mining tremors, volcanic events and icequakes are presented.

8

Anomalous piezoelectric effect: analysis of experimental data and numerical simulation

Teisseyre K., Hadjicontis V., Mavromatou C.

Acta Geophysica Polonica

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2001

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Vol. 49, nr 4

449-462

EN

Interpretation of laboratory experiments on anomalous piezoelectric effects found in samples of various non-piezoelectric rocks leads us to formulate the model of transient electric polarization and its relaxation. A change of the load results in polarization in the rock, the electric signal appears immediately at a given moment, and later we observe the signal relaxation as an exponential decrease in time. Assumption of double mechanism of relaxation or, for most cases, even triple mechanism: quick, slower and the slowest relaxation, is made to obtain a better agreement between simulation and the experiments. Other complications of the model seem to be useful in the search for adequate reconstruction of electric signal rise and decay. The following elements were assumed, and positively tested in many simulations: opposite components of polarization in case of serrate stimulus curve (load rate shaped like toothed curve), the large bay of the opposite polarization during release of the load (theoretically not expected in non-piezoelectric materials) and kind of the polarization saturation during the test with the repeating load history.

9

Numerical simulation of resistivity changes caused by water infiltration

Teisseyre K., Teisseyre R.

Acta Geophysica Polonica

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1999

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Vol. 47, nr 1

41-57

EN

The paper presents a method of calculation of electric resistivity (including anisotropy) for a compound medium with cracks/inclusions infiltrated by fluid. A comparison with other similar models is made. An application for an analysis of water infiltration and the resistivity changes in bedrock of the Czorsztyn-Niedzica water reservoir is discussed.