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A. Lyubushin

Russian academy of sciences, Physics Earth, Faculty Member

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In 1977 he graduated from the Moscow Institute of Physics and Technology, Faculty of Aerophysics and Space Research. In 1977-1984 worked at the Institute of Problems of Mechanics of the USSR Academy of Sciences, where in 1981 he defended his Ph.D. physics and mathematics sciences on numerical methods of optimal control and their application to problems of aircraft dynamics. He has been working at the Institute of Earth Physics of the Russian Academy of Sciences since 1984, currently as a chief researcher and head of the laboratory. In 1996 he defended his dissertation as a Doctor of Physics and Mathematics Sciences on mathematical issues of information analysis of geophysical monitoring systems. Area of scientific interests: mathematical and methodological issues of statistical analysis of multidimensional information of geophysical and environmental monitoring systems, earthquake forecasting.

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Vadim S Bobrovskiy

Сергей Шопин

Università degli Studi "G. d'Annunzio" Chieti Pescara

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Leyla Sugaipova

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Papers by A. Lyubushin

Experience of Complexation of Global Geophysical Observations

Geodynamics & Tectonophysics, 2016

The technique of joint analysis of heterogeneous time series of geophysical monitoring systems fo... more The technique of joint analysis of heterogeneous time series of geophysical monitoring systems for the purpose of detecting time intervals and specific periods of bursts of synchronous behavior is presented. The technique is based on the use of the Fourier-aggregated signals and spectral measures of coherent behavior of multivariate time series, estimated in moving time windows. The article presents results of the analysis of data of underground electrical surveys at stations located in Kamchatka, Altai and Italy; the data were analysed together with torsion pendulum movements in Tula (Russia) and the time series of seismic noise parameters at the Japanese islands for the interval 2012-2015. The analysis identified a number of significant bursts of coherent behavior for these observations, some of which are presumably due to the strong mantle Okhotsk Sea earthquake of 24 May 2013. The coherent behavior of various geophysical fields before and after strong earthquakes is interpreted as a manifestation of the general pattern of increasing synchronization of fluctuations of complex systems at their approach to the rapid changes in their properties.

Microseismic anomalies before the Sumatra earthquake of December 26, 2004

Izvestiya, Physics of the Solid Earth, 2007

Microseismic records from five broadband IRIS stations located at distances of 1000-2000 km from ... more Microseismic records from five broadband IRIS stations located at distances of 1000-2000 km from the earthquake source are studied. Unordinary programs are used to extract hidden periodicities, determine signal coherence at different stations, and reveal asymmetry in wave amplitudes. The records obtained at a few stations 60 h before the Sumatra earthquake include periodic oscillations in the range of periods from 20 to 60 min that arose after the McQuary earthquake and continued for about 24 h. Synchronization of waves recorded at all stations commenced 53 h before the Sumatra earthquake and continued up to the time of the earthquake, with the predominant period gradually increasing from a few minutes to tens of minutes.

Spectral Analysis of Caspian Level Variations

by Mikhail Bolgov and A. Lyubushin

23rd International Conference on Offshore Mechanics and Arctic Engineering, Volume 2, 2004

Survey Paper Method of Successive Approximations for Solution of Optimal Control Problems

SUMMARY The paper contains a survey of results devoted to one of the numerical methods of optimal... more SUMMARY The paper contains a survey of results devoted to one of the numerical methods of optimal control-the method of successive approximations. This method is based on Pontryagin's maximum principle and is known in the English literature as the min-H method. Various modifications of the method and some theoretical results on its convergence are presented. Examples of applications of the method for the calculation of optimal trajectories are given. The method of small parameters which is close to the method of successive approximations, is also described.

Russian Academy of Sciences

$Research paper thumbnail of Chapter 15 Multifractal Parameters of Low-Frequency$

Chapter 15 Multifractal Parameters of Low-Frequency

Low-frequency microseismic oscillations serve as an important source of information about process... more Low-frequency microseismic oscillations serve as an important source of information about processes proceeding in the crust, in spite of the fact that the main energy of these oscillations is caused by processes proceeding in the atmosphere and ocean, such as variations in the atmospheric pressure and the action of oceanic waves on the coast and shelf. The relation of low-frequency microseisms having periods of 5–500 s to the intensity of oceanic waves is comprehensively investigated in [Friedrich et al., 1998; Kobayashi andNishida, 1998; Tanimoto et al., 1998; Tanimoto andUm, 1999; Ekstrom, 2001; Tanimoto, 2001; 2005; Berger et al., 2004; Kurrle and WidmerSchnidrig, 2006; Stehly et al., 2006; Rhie and Romanowicz, 2004; 2006]. The reverse influence of low-frequency microseisms with still longer periods (from several tens to a few hundreds of minutes) on atmospheric pressure variations due to slow wave-like deformations of the lithosphere were investigated in [Lin’kov, 1987; Lin’kov ...

Periodical Oscillations of Microseisms before the Sumatra Earthquake of December 26, 2004

This work continues a series of papers published in Izvestiya, Physics of the Solid Earth, in 200... more This work continues a series of papers published in Izvestiya, Physics of the Solid Earth, in 2003–2006 and devoted to the detection and study of periodic oscillations in the seismic flow and synchronization effects arising before strong earthquakes [Sobolev, 2003, 2004; Sobolev et al., 2005; Sobolev and Lyubushin, 2006; Lyubushin and Sobolev, 2006]. These studies were essentially based on the concepts of the dynamics of nonequilibrium media, including self-organization of the seismic process [Nicolis and Prigogine, 1977; Bak et al., 1989; Sornette and Sammis, 1995; Ott, 2002]. It is assumed that, in a metastable lithosphere immedia-tely before an earthquake, natural periodic oscillations arise and/or oscillations from external sources are selectively amplified, with the microseismic field showing collective behavior. Processing of 20-Hz records obtained at the Petropavlovsk IRIS station before the Kronotskii earthquake revealed waves at periods of a few tens of minutes in the micro...

Microseismic impulses as earthquake precursors

Izvestiya Physics of the Solid Earth, 2006

are investigated with the use of the Spectra Analyzer interactive program, designed for the analy... more are investigated with the use of the Spectra Analyzer interactive program, designed for the analysis of properties of scalar time series. It is found that, 5 to 10 days before the shocks, stations nearest to the sources of these earthquakes recorded pulsed vibrations a few minutes long that were separated by intervals of a few tens of minutes. The shape asymmetry of the pulses characterized by different amplitudes of positive and negative polarity phases increased toward the earthquake onset time, as did the frequency and regularity of the pulse sequence. It is assumed that the nature of this phenomenon is related to self-organization properties of the seismic process in a metastable lithosphere and to the synchronization of vibrations in the inner and outer shells of the Earth, including chaotic and quasi-periodic components.

EXPERIENCE OF COMPLEXATION OF GLOBAL GEOPHYSICAL OBSERVATIONS ОПЫТ КОМПЛЕКСИРОВАНИЯ ГЛОБАЛЬНЫХ ГЕОФИЗИЧЕСКИХ GEODYNAMICS & TECTONOPHYSICS

by Vadim S Bobrovskiy, A. Lyubushin, and Сергей Шопин

The technique of joint analysis of heterogeneous time series of geophysical monitoring systems fo... more The technique of joint analysis of heterogeneous time series of geophysical monitoring systems for the purpose of detecting time intervals and specific periods of bursts of synchronous behavior is presented. The technique is based on the use of the Fourier-aggregated signals and spectral measures of coherent behavior of multivariate time series, estimated in moving time windows. The article presents results of the analysis of data of underground electrical surveys at stations located in Kamchatka, Altai and Italy; the data were analysed together with torsion pendulum movements in Tula (Russia) and the time series of seismic noise parameters at the Japanese islands for the interval 2012-2015. The analysis identified a number of significant bursts of coherent behavior for these observations, some of which are presumably due to the strong mantle Okhotsk Sea earthquake of 24 May 2013. The coherent behavior of various geophysical fields before and after strong earthquakes is interpreted as a manifestation of the general pattern of increasing synchronization of fluctuations of complex systems at their approach to the rapid changes in their properties.

STATISTICAL METHODS FOR RIVER’S RUNOFF FORECAST

by Stéphane Canu and A. Lyubushin

ABSTRACT Statistical methods of data analysis are applied to monthly runoff values of rivers. The... more ABSTRACT Statistical methods of data analysis are applied to monthly runoff values of rivers. The analysis is based on the theory of periodically correlated random processes. This approach takes into account both deterministic and stochastic components of seasonal variations of runoff data. Prediction formulae of runoff value one month ahead, based on 1-12 preceding monthly runoff values, are derived. This method was applied to 9 rivers with different hydrological regimes.

Multidimensional Wavelet Analysis of Point Processes

Methodologically, analysis of seismic catalogs is more difficult than processing of time series. ... more Methodologically, analysis of seismic catalogs is more difficult than processing of time series. This is due to the fact that the analysis of point processes, including earthquakes sequences, does not allow the direct application of a vast variety of methods, parametrical models, and fast algorithms developed in the theory of signals. Actually, application of these methods requires a preliminary conversion of seismic catalogs to time series, which are sequences of values with a given constant time step. Formally, this conversion is not difficult and can be realized via calculation of either average values of a certain catalog parameter (for example, energy released during an earthquake) in successive non-overlapping time windows of a constant width or cumulative values of these characteristics with a constant time step (cumulative curves). However, the resulting time series are essentially non-Gaussian and include either outliers or step-like features (in cumulative curves) due to t...

$Research paper thumbnail of Multifractal Parameters of Low-Frequency Microseisms$

Multifractal Parameters of Low-Frequency Microseisms

Geoplanet: Earth and Planetary Sciences, 2010

Low-frequency microseismic oscillations serve as an important source of information about process... more Low-frequency microseismic oscillations serve as an important source of information about processes proceeding in the crust, in spite of the fact that the main energy of these oscillations is caused by processes proceeding in the atmosphere and ocean, such as variations in the atmospheric pressure and the action of oceanic waves on the coast and shelf. The relation of low-frequency microseisms having periods of 5-500 s to the intensity of oceanic waves is comprehensively investigated in [Friedrich et al.]. The reverse influence of low-frequency microseisms with still longer periods (from several tens to a few hundreds of minutes) on atmospheric pressure variations due to slow wave-like deformations of the lithosphere were investigated in . Actually, the Earth's crust is a medium propagating the energy from atmospheric and oceanic processes, and since the transmitting properties of the crust depend on its state, the statistical properties of microseisms reflect changes in lithospheric properties.

Wavelet-based coherence measures of global seismic noise properties

Journal of Seismology, 2014

Your article is protected by copyright and all rights are held exclusively by Springer Science +B... more Your article is protected by copyright and all rights are held exclusively by Springer Science +Business Media Dordrecht. This e-offprint is for personal use only and shall not be selfarchived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".

Prognostic properties of low-frequency seismic noise

Natural Science, 2012

The prognostic properties of four low-frequency seismic noise statistics are discussed: multifrac... more The prognostic properties of four low-frequency seismic noise statistics are discussed: multifractal singularity spectrum support width, wavelet-based smoothness index of seismic noise waveforms, minimum normalized entropy of squared orthogonal wavelet coefficients and index of linear predictability. The proposed methods are illustrated by data analysis from broadband seismic network F-net in Japan for more than 15 years of observation: since the beginning of 1997 up to 15 May 2012. The previous analysis of multi-fractal properties of low-frequency seismic noise allowed a hypothesis about approaching Japan Islands to a future seismic catastrophe to be formulated at the middle of 2008. The base for such a hypothesis was statistically significant decreasing of multi-fractal singularity spectrum support width mean value. The peculiarities of correlation coefficient estimate within 1 year time window between median values of singularity spectra support width and generalized Hurst exponent allowed to make a decision that starting from July of 2010 Japan come to the state of waiting strong earthquake. This prediction of Tohoku mega-earthquake, initially with estimate of lower magnitude as 8.3 only (at the middle of 2008) and further on with estimate of the time beginning of waiting earthquake (from the middle of 2010) was published in advance in a number of scientific articles and abstracts on international conferences. It is shown that other 3 statistics (except singularity spectrum support width) could extract seismically danger domains as well. The analysis of seismic noise data after Tohoku mega-earthquake indicates increasing of probability of the 2nd strong earthquake within the region where the north part of Philippine sea plate is approaching island Honshu (Nankai Trough). 30 32 34 36 38 40 42 44 46 N, deg 0.42 En Figure 3. Averaged maps of seismic noise waveforms smoothness index (a', b', c') and minimum normalized entropy of squared wavelet coefficients (a″, b″, c″) for 3 successive time intervals. Stars indicate epicenters of earthquakes: 25 of September 2003, M = 8.3 (a', a″) and 11 of March 2011, M = 9.0 (b', b″).

A New Method for Identifying Seismicity Periodicities

Journal of Volcanology and Seismology

Analysis of Canonical Coherences in the Problems of Geophysical Monitoring

Izvestiya Physics of the Solid Earth

Synchronous Variations in the Caspian Sea Level from Coastal Observations in 1977–1991

Izvestiya Atmospheric and Oceanic Physics

The time series of variations in the Caspian Sea level derived from synchronous measurements at 1... more The time series of variations in the Caspian Sea level derived from synchronous measurements at 15 coastal stations with a sampling interval of 6 h over the period of observations from the beginning of 1977 to the end of 1991 are considered. Collective (common) components of both stationary and nonstationary character were to be recognized in this 15-dimensional time series. Nonstandard multidimensional spectral methods of the estimation of canonical coherences in a moving time window, as well as the spectral analysis of aggregated signals, were used to analyze the data. This analysis detected common harmonic components forming semidiurnal and diurnal groups of tidal harmonics, seasonal variations, and the frequency band of variations with a strong coherence in the range of periods from 4 to 8 days. Additionally, we identified a common lowfrequency harmonic with a period of 12.85 yr, which is supposedly associated with the influence of cyclic changes of a global character on variations in the Caspian Sea level.

A robust wavelet-aggregated signal for geophysical monitoring problems

Izvestiya Physics of the Solid Earth

A modification of the method of wavelet-aggregated signal intended for the analysis of multidimen... more A modification of the method of wavelet-aggregated signal intended for the analysis of multidimensional time series of monitoring systems, with account taken of the existence of large outliers in the values of wavelet coefficients, is considered. This property follows from the ability of wavelet expansions to accumulate a maximum amount of information in a relatively small amount of coefficients, as well as from the nature of the data analyzed, in which outliers are not due to errors of recording systems. The non-Gaussian property of the distribution of wavelet coefficients requires modification of conventional schemes used for the multidimensional analysis of canonical and principal components in order to make results of this analysis statistically more reliable. An approach to the solution of this problem is presented, along with its applications to the analysis of geophysical data (time series of monitoring systems and seismic catalogs) and comparison of their results with those obtained by applying the previous nonrobust approach.

Synchronization of Microseismic Variations within a Minute Range of Periods

Izvestiya Physics of the Solid Earth

Records obtained at the Petropavlovsk, Yuzhno-Sakhalinsk, Magadan, Yakutsk, and Obninsk IRIS broa... more Records obtained at the Petropavlovsk, Yuzhno-Sakhalinsk, Magadan, Yakutsk, and Obninsk IRIS broadband stations before the Kronotski (Kamchatka) earthquake are investigated with the use of various programs of processing and analysis of time series. Intervals of a stable manifestation of one or several periods of microseisms (synchronization intervals) inferred from data of different stations do not necessarily coincide in time. No anomalous meteorological effects are recorded in these intervals. Geodynamic phenomena on global and regional scales influence the duration and intensity of the synchronization intervals. As distinct from other stations, the Petropavlovsk record revealed asymmetric variations of the relaxation type that arose five days before the Kronotski earthquake and three days before the onset of intense foreshock activation. The amplitude of variations at this station exceeds the level of other stations by an order of magnitude, which indicates that the source of this earthquake was located in the Pacific seismically active region. The number of predominant periods at the Petropavlovsk station decreases toward the time moment of the Kronotski earthquake, and the polymodal spectrum becomes unimodal, primarily due to the loss of shorter periods: a period of 37 min is most clearly expressed 1 h before the earthquake. The synchronization intervals of variations, as well as the foreshock activation, are indicators of the unstable state of a seismically active region.

Seeking periodicity within sequences of POT-moments of daily runoff time series

This report investigates periodicities within sequences of peaks over threshold (POT) moments of ... more This report investigates periodicities within sequences of peaks over threshold (POT) moments of river discharges. The method for the identification of periodicities was proposed in , and can be regarded as the generalization of the spectra for the sequence of events. The graphic of this function indicates which probe values of the frequency provide the maximum gain in the log-likelihood function increment with respect to a pure random model. Thus, the points of maximum of the function detect periodic components of the point process.

Experience of Complexation of Global Geophysical Observations

Geodynamics & Tectonophysics, 2016

The technique of joint analysis of heterogeneous time series of geophysical monitoring systems fo... more The technique of joint analysis of heterogeneous time series of geophysical monitoring systems for the purpose of detecting time intervals and specific periods of bursts of synchronous behavior is presented. The technique is based on the use of the Fourier-aggregated signals and spectral measures of coherent behavior of multivariate time series, estimated in moving time windows. The article presents results of the analysis of data of underground electrical surveys at stations located in Kamchatka, Altai and Italy; the data were analysed together with torsion pendulum movements in Tula (Russia) and the time series of seismic noise parameters at the Japanese islands for the interval 2012-2015. The analysis identified a number of significant bursts of coherent behavior for these observations, some of which are presumably due to the strong mantle Okhotsk Sea earthquake of 24 May 2013. The coherent behavior of various geophysical fields before and after strong earthquakes is interpreted as a manifestation of the general pattern of increasing synchronization of fluctuations of complex systems at their approach to the rapid changes in their properties.

Microseismic anomalies before the Sumatra earthquake of December 26, 2004

Izvestiya, Physics of the Solid Earth, 2007

Microseismic records from five broadband IRIS stations located at distances of 1000-2000 km from ... more Microseismic records from five broadband IRIS stations located at distances of 1000-2000 km from the earthquake source are studied. Unordinary programs are used to extract hidden periodicities, determine signal coherence at different stations, and reveal asymmetry in wave amplitudes. The records obtained at a few stations 60 h before the Sumatra earthquake include periodic oscillations in the range of periods from 20 to 60 min that arose after the McQuary earthquake and continued for about 24 h. Synchronization of waves recorded at all stations commenced 53 h before the Sumatra earthquake and continued up to the time of the earthquake, with the predominant period gradually increasing from a few minutes to tens of minutes.

Spectral Analysis of Caspian Level Variations

by Mikhail Bolgov and A. Lyubushin

23rd International Conference on Offshore Mechanics and Arctic Engineering, Volume 2, 2004

Survey Paper Method of Successive Approximations for Solution of Optimal Control Problems

SUMMARY The paper contains a survey of results devoted to one of the numerical methods of optimal... more SUMMARY The paper contains a survey of results devoted to one of the numerical methods of optimal control-the method of successive approximations. This method is based on Pontryagin's maximum principle and is known in the English literature as the min-H method. Various modifications of the method and some theoretical results on its convergence are presented. Examples of applications of the method for the calculation of optimal trajectories are given. The method of small parameters which is close to the method of successive approximations, is also described.

Russian Academy of Sciences

$Research paper thumbnail of Chapter 15 Multifractal Parameters of Low-Frequency$

Chapter 15 Multifractal Parameters of Low-Frequency

Low-frequency microseismic oscillations serve as an important source of information about process... more Low-frequency microseismic oscillations serve as an important source of information about processes proceeding in the crust, in spite of the fact that the main energy of these oscillations is caused by processes proceeding in the atmosphere and ocean, such as variations in the atmospheric pressure and the action of oceanic waves on the coast and shelf. The relation of low-frequency microseisms having periods of 5–500 s to the intensity of oceanic waves is comprehensively investigated in [Friedrich et al., 1998; Kobayashi andNishida, 1998; Tanimoto et al., 1998; Tanimoto andUm, 1999; Ekstrom, 2001; Tanimoto, 2001; 2005; Berger et al., 2004; Kurrle and WidmerSchnidrig, 2006; Stehly et al., 2006; Rhie and Romanowicz, 2004; 2006]. The reverse influence of low-frequency microseisms with still longer periods (from several tens to a few hundreds of minutes) on atmospheric pressure variations due to slow wave-like deformations of the lithosphere were investigated in [Lin’kov, 1987; Lin’kov ...

Periodical Oscillations of Microseisms before the Sumatra Earthquake of December 26, 2004

This work continues a series of papers published in Izvestiya, Physics of the Solid Earth, in 200... more This work continues a series of papers published in Izvestiya, Physics of the Solid Earth, in 2003–2006 and devoted to the detection and study of periodic oscillations in the seismic flow and synchronization effects arising before strong earthquakes [Sobolev, 2003, 2004; Sobolev et al., 2005; Sobolev and Lyubushin, 2006; Lyubushin and Sobolev, 2006]. These studies were essentially based on the concepts of the dynamics of nonequilibrium media, including self-organization of the seismic process [Nicolis and Prigogine, 1977; Bak et al., 1989; Sornette and Sammis, 1995; Ott, 2002]. It is assumed that, in a metastable lithosphere immedia-tely before an earthquake, natural periodic oscillations arise and/or oscillations from external sources are selectively amplified, with the microseismic field showing collective behavior. Processing of 20-Hz records obtained at the Petropavlovsk IRIS station before the Kronotskii earthquake revealed waves at periods of a few tens of minutes in the micro...

Microseismic impulses as earthquake precursors

Izvestiya Physics of the Solid Earth, 2006

are investigated with the use of the Spectra Analyzer interactive program, designed for the analy... more are investigated with the use of the Spectra Analyzer interactive program, designed for the analysis of properties of scalar time series. It is found that, 5 to 10 days before the shocks, stations nearest to the sources of these earthquakes recorded pulsed vibrations a few minutes long that were separated by intervals of a few tens of minutes. The shape asymmetry of the pulses characterized by different amplitudes of positive and negative polarity phases increased toward the earthquake onset time, as did the frequency and regularity of the pulse sequence. It is assumed that the nature of this phenomenon is related to self-organization properties of the seismic process in a metastable lithosphere and to the synchronization of vibrations in the inner and outer shells of the Earth, including chaotic and quasi-periodic components.

EXPERIENCE OF COMPLEXATION OF GLOBAL GEOPHYSICAL OBSERVATIONS ОПЫТ КОМПЛЕКСИРОВАНИЯ ГЛОБАЛЬНЫХ ГЕОФИЗИЧЕСКИХ GEODYNAMICS & TECTONOPHYSICS

by Vadim S Bobrovskiy, A. Lyubushin, and Сергей Шопин

The technique of joint analysis of heterogeneous time series of geophysical monitoring systems fo... more The technique of joint analysis of heterogeneous time series of geophysical monitoring systems for the purpose of detecting time intervals and specific periods of bursts of synchronous behavior is presented. The technique is based on the use of the Fourier-aggregated signals and spectral measures of coherent behavior of multivariate time series, estimated in moving time windows. The article presents results of the analysis of data of underground electrical surveys at stations located in Kamchatka, Altai and Italy; the data were analysed together with torsion pendulum movements in Tula (Russia) and the time series of seismic noise parameters at the Japanese islands for the interval 2012-2015. The analysis identified a number of significant bursts of coherent behavior for these observations, some of which are presumably due to the strong mantle Okhotsk Sea earthquake of 24 May 2013. The coherent behavior of various geophysical fields before and after strong earthquakes is interpreted as a manifestation of the general pattern of increasing synchronization of fluctuations of complex systems at their approach to the rapid changes in their properties.

STATISTICAL METHODS FOR RIVER’S RUNOFF FORECAST

by Stéphane Canu and A. Lyubushin

ABSTRACT Statistical methods of data analysis are applied to monthly runoff values of rivers. The... more ABSTRACT Statistical methods of data analysis are applied to monthly runoff values of rivers. The analysis is based on the theory of periodically correlated random processes. This approach takes into account both deterministic and stochastic components of seasonal variations of runoff data. Prediction formulae of runoff value one month ahead, based on 1-12 preceding monthly runoff values, are derived. This method was applied to 9 rivers with different hydrological regimes.

Multidimensional Wavelet Analysis of Point Processes

Methodologically, analysis of seismic catalogs is more difficult than processing of time series. ... more Methodologically, analysis of seismic catalogs is more difficult than processing of time series. This is due to the fact that the analysis of point processes, including earthquakes sequences, does not allow the direct application of a vast variety of methods, parametrical models, and fast algorithms developed in the theory of signals. Actually, application of these methods requires a preliminary conversion of seismic catalogs to time series, which are sequences of values with a given constant time step. Formally, this conversion is not difficult and can be realized via calculation of either average values of a certain catalog parameter (for example, energy released during an earthquake) in successive non-overlapping time windows of a constant width or cumulative values of these characteristics with a constant time step (cumulative curves). However, the resulting time series are essentially non-Gaussian and include either outliers or step-like features (in cumulative curves) due to t...

$Research paper thumbnail of Multifractal Parameters of Low-Frequency Microseisms$

Multifractal Parameters of Low-Frequency Microseisms

Geoplanet: Earth and Planetary Sciences, 2010

Low-frequency microseismic oscillations serve as an important source of information about process... more Low-frequency microseismic oscillations serve as an important source of information about processes proceeding in the crust, in spite of the fact that the main energy of these oscillations is caused by processes proceeding in the atmosphere and ocean, such as variations in the atmospheric pressure and the action of oceanic waves on the coast and shelf. The relation of low-frequency microseisms having periods of 5-500 s to the intensity of oceanic waves is comprehensively investigated in [Friedrich et al.]. The reverse influence of low-frequency microseisms with still longer periods (from several tens to a few hundreds of minutes) on atmospheric pressure variations due to slow wave-like deformations of the lithosphere were investigated in . Actually, the Earth's crust is a medium propagating the energy from atmospheric and oceanic processes, and since the transmitting properties of the crust depend on its state, the statistical properties of microseisms reflect changes in lithospheric properties.

Wavelet-based coherence measures of global seismic noise properties

Journal of Seismology, 2014

Your article is protected by copyright and all rights are held exclusively by Springer Science +B... more Your article is protected by copyright and all rights are held exclusively by Springer Science +Business Media Dordrecht. This e-offprint is for personal use only and shall not be selfarchived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".

Prognostic properties of low-frequency seismic noise

Natural Science, 2012

The prognostic properties of four low-frequency seismic noise statistics are discussed: multifrac... more The prognostic properties of four low-frequency seismic noise statistics are discussed: multifractal singularity spectrum support width, wavelet-based smoothness index of seismic noise waveforms, minimum normalized entropy of squared orthogonal wavelet coefficients and index of linear predictability. The proposed methods are illustrated by data analysis from broadband seismic network F-net in Japan for more than 15 years of observation: since the beginning of 1997 up to 15 May 2012. The previous analysis of multi-fractal properties of low-frequency seismic noise allowed a hypothesis about approaching Japan Islands to a future seismic catastrophe to be formulated at the middle of 2008. The base for such a hypothesis was statistically significant decreasing of multi-fractal singularity spectrum support width mean value. The peculiarities of correlation coefficient estimate within 1 year time window between median values of singularity spectra support width and generalized Hurst exponent allowed to make a decision that starting from July of 2010 Japan come to the state of waiting strong earthquake. This prediction of Tohoku mega-earthquake, initially with estimate of lower magnitude as 8.3 only (at the middle of 2008) and further on with estimate of the time beginning of waiting earthquake (from the middle of 2010) was published in advance in a number of scientific articles and abstracts on international conferences. It is shown that other 3 statistics (except singularity spectrum support width) could extract seismically danger domains as well. The analysis of seismic noise data after Tohoku mega-earthquake indicates increasing of probability of the 2nd strong earthquake within the region where the north part of Philippine sea plate is approaching island Honshu (Nankai Trough). 30 32 34 36 38 40 42 44 46 N, deg 0.42 En Figure 3. Averaged maps of seismic noise waveforms smoothness index (a', b', c') and minimum normalized entropy of squared wavelet coefficients (a″, b″, c″) for 3 successive time intervals. Stars indicate epicenters of earthquakes: 25 of September 2003, M = 8.3 (a', a″) and 11 of March 2011, M = 9.0 (b', b″).

A New Method for Identifying Seismicity Periodicities

Journal of Volcanology and Seismology

Analysis of Canonical Coherences in the Problems of Geophysical Monitoring

Izvestiya Physics of the Solid Earth

Synchronous Variations in the Caspian Sea Level from Coastal Observations in 1977–1991

Izvestiya Atmospheric and Oceanic Physics

The time series of variations in the Caspian Sea level derived from synchronous measurements at 1... more The time series of variations in the Caspian Sea level derived from synchronous measurements at 15 coastal stations with a sampling interval of 6 h over the period of observations from the beginning of 1977 to the end of 1991 are considered. Collective (common) components of both stationary and nonstationary character were to be recognized in this 15-dimensional time series. Nonstandard multidimensional spectral methods of the estimation of canonical coherences in a moving time window, as well as the spectral analysis of aggregated signals, were used to analyze the data. This analysis detected common harmonic components forming semidiurnal and diurnal groups of tidal harmonics, seasonal variations, and the frequency band of variations with a strong coherence in the range of periods from 4 to 8 days. Additionally, we identified a common lowfrequency harmonic with a period of 12.85 yr, which is supposedly associated with the influence of cyclic changes of a global character on variations in the Caspian Sea level.

A robust wavelet-aggregated signal for geophysical monitoring problems

Izvestiya Physics of the Solid Earth

A modification of the method of wavelet-aggregated signal intended for the analysis of multidimen... more A modification of the method of wavelet-aggregated signal intended for the analysis of multidimensional time series of monitoring systems, with account taken of the existence of large outliers in the values of wavelet coefficients, is considered. This property follows from the ability of wavelet expansions to accumulate a maximum amount of information in a relatively small amount of coefficients, as well as from the nature of the data analyzed, in which outliers are not due to errors of recording systems. The non-Gaussian property of the distribution of wavelet coefficients requires modification of conventional schemes used for the multidimensional analysis of canonical and principal components in order to make results of this analysis statistically more reliable. An approach to the solution of this problem is presented, along with its applications to the analysis of geophysical data (time series of monitoring systems and seismic catalogs) and comparison of their results with those obtained by applying the previous nonrobust approach.

Synchronization of Microseismic Variations within a Minute Range of Periods

Izvestiya Physics of the Solid Earth

Records obtained at the Petropavlovsk, Yuzhno-Sakhalinsk, Magadan, Yakutsk, and Obninsk IRIS broa... more Records obtained at the Petropavlovsk, Yuzhno-Sakhalinsk, Magadan, Yakutsk, and Obninsk IRIS broadband stations before the Kronotski (Kamchatka) earthquake are investigated with the use of various programs of processing and analysis of time series. Intervals of a stable manifestation of one or several periods of microseisms (synchronization intervals) inferred from data of different stations do not necessarily coincide in time. No anomalous meteorological effects are recorded in these intervals. Geodynamic phenomena on global and regional scales influence the duration and intensity of the synchronization intervals. As distinct from other stations, the Petropavlovsk record revealed asymmetric variations of the relaxation type that arose five days before the Kronotski earthquake and three days before the onset of intense foreshock activation. The amplitude of variations at this station exceeds the level of other stations by an order of magnitude, which indicates that the source of this earthquake was located in the Pacific seismically active region. The number of predominant periods at the Petropavlovsk station decreases toward the time moment of the Kronotski earthquake, and the polymodal spectrum becomes unimodal, primarily due to the loss of shorter periods: a period of 37 min is most clearly expressed 1 h before the earthquake. The synchronization intervals of variations, as well as the foreshock activation, are indicators of the unstable state of a seismically active region.

Seeking periodicity within sequences of POT-moments of daily runoff time series

This report investigates periodicities within sequences of peaks over threshold (POT) moments of ... more This report investigates periodicities within sequences of peaks over threshold (POT) moments of river discharges. The method for the identification of periodicities was proposed in , and can be regarded as the generalization of the spectra for the sequence of events. The graphic of this function indicates which probe values of the frequency provide the maximum gain in the log-likelihood function increment with respect to a pure random model. Thus, the points of maximum of the function detect periodic components of the point process.