Natalya Zhukova

Analysis of the Complexity of Seismic Data Sets: Case Study for Caucasus

Abstract The investigation of the dynamics of complex seismic processes remains a major scientific challenge. Presently this problem is viewed in the light of modern concepts of the spatiotemporal behaviour of highly nonlinear or complex natural systems. The significant progress in this direction achieved over recent decades has paved a new avenue of research in the investigation of qualitative and quantitative aspects of the dynamics of seismic processes. Special attention has been paid to the elaboration of new methods of measuring the complexity of both global and local dynamics from seismic data sets. In this chapter, we present examples using several modern data analysis approaches on data sets related to seismic activity in the Caucasus. These data analysis methods are often used for the qualitative and quantitative evaluation of the complexity of natural processes, including seismic processes in different parts of globe.

Phase Space Portraits of Earthquake Time Series of Caucasus

Abstract Many studies have been devoted to the statistical analysis of earthquake time series (ETS) in recent years. Modern methods of nonlinear dynamics, applied to ETS, give controversial results: some authors have proved the existence of strange attractors (which means that ETS can be represented by deterministic chaos model), others have demonstrated the absence of such ordered structures. This chapter analyses the spatiotemporal parameters of seismic rate and reveals nonlinear structures in the phase space plots constructed for low seismicity areas, as well as for seismic areas before, during and after the occurrence of the strongest Caucasian earthquakes: Spitak (1988) and Racha (1991). The seismic phase portraits and recurrence plots constructed for different time windows, epicentral distances and magnitude thresholds, reveal some patterns of seismic process dynamics that could be possibly related to precursors of strong earthquakes.

M9 Tohoku Earthquake Hydro- and Seismic Response in the Caucasus and North Turkey

Presently, there are a lot of observations on the significant impact of strong remote earthquakes on underground water and local seismicity. Teleseismic wave trains of strong earthquakes give rise to several hydraulic effects in boreholes, namely permanent water level changes and water level oscillations, which closely mimic the seismograms (hydro-seismograms). Clear identical anomalies in the deep borehole water levels have been observed on a large part of the territory of Georgia during passing of the S and Love–Rayleigh teleseismic waves (including also multiple surface Rayleigh waves) of the 2011 Tohoku M9 earthquake. The analysis carried out in order to find dynamically triggered events (non-volcanic tremors) of the Tohoku earthquake by the accepted methodology has not revealed a clear tremor signature in the test area: the Caucasus and North Turkey. The possible mechanisms of some seismic signals of unknown origin observed during passage of teleseismic waves of Tohoku earthquake are discussed.