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1

Some Probabilistic and Statistical Properties of the Seismic Regime of Zemmouri (Algeria) Seismoactive Zone

Baddari K., Bellalem F., Baddari I., Makdeche S.

Acta Geophysica

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2016

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Vol. 64, no. 5

1275--1310

EN

Statistical tests have been used to adjust the Zemmouri seismic data using a distribution function. The Pareto law has been used and the probabilities of various expected earthquakes were computed. A mathematical expression giving the quantiles was established. The extreme values limiting law confirmed the accuracy of the adjustment method. Using the moment magnitude scale, a probabilistic model was made to predict the occurrences of strong earthquakes. The seismic structure has been characterized by the slope of the recurrence plot γ, fractal dimension D, concentration parameter Ksr, Hurst exponents Hr and Ht. The values of D, γ, Ksr, Hr, and Ht diminished many months before the principal seismic shock (M = 6.9) of the studied seismoactive zone has occurred. Three stages of the deformation of the geophysical medium are manifested in the variation of the coefficient G% of the clustering of minor seismic events.

2

Effect of Stress-Strain Conditions on Physical Precursors and Failure Stages Development in Rock Samples

Baddari K., Frolov A. D., Tourtchine V., Rahmoune F., Makdeche S.

Acta Geophysica

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2015

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Vol. 63, no. 1

62--102

EN

Precursory stages of failure development in large rock samples were studied and simultaneous observations of the space-time variation of several physical fields were carried out under different stress-strain states. The failure process was studied in detail. A hierarchical structure of discreet rock medium was obtained after loading. It was found that the moisture reduced the rock strength, increased the microcrack distribution and influenced the shape of the failure physical precursors. The rise in temperature up to 400 °C affected the physical precursors at the intermediate and final stages of the failure. Significant variations were detected in the acoustic and electromagnetic emissions. The coalescence criterion was slightly depending on the rock moisture and temperature effect. The possibility of identifying the precursory stage of failure at different strain conditions by means of a complex parameter derived from the convolution of physical recorded data is shown. The obtained results point out the efficiency of the laboratory modelling of seismic processes.

3

Probabilistic model to forecast earthquakes in the Zemmouri (Algeria) seismoactive area on the basis of moment magnitude scale distribution functions

Baddari K., Makdeche S., Bellalem F.

Acta Geophysica

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2013

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Vol. 61, no. 1

60--83

EN

Based on the moment magnitude scale, a probabilistic model was developed to predict the occurrences of strong earthquakes in the seis- moactive area of Zemmouri, Algeria. Firstly, the distributions of earthquake magnitudes Mi were described using the distribution function F0(m), which adjusts the magnitudes considered as independent random variables. Secondly, the obtained result, i.e., the distribution function F0(m) of the variables Mi was used to deduce the distribution functions G(x) and H(y) of the variables Yi = LogM0,i andZi = M0,i, where (Yi)i and (Zi)i are independent. Thirdly,some forecast for moments of the future earthquakes in the studied area is given.

4

Effect of temperature on the physical precursors of rock block failure

Baddari K., Frolov A.D., Tourtchine V., Makdeche S., Rahmoune F.

Acta Geophysica

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2012

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Vol. 60, no. 4

1007-1029

EN

The influence of temperature (25-400 °C) on the variations of mechanical, acoustic, electric and electromagnetic precursors of rock failure has been shown experimentally. The most significant variations were detected in the principal parameters of the acoustic and electromagnetic emissions whose impulse energy underwent a fast growth. However, the general character of hierarchical evolution stages of micro and macrofailure was practically unchanged. This has been confirmed by the so-called concentration parameter of rupture, which is theoretically calculated and checked in experiments; its space-time variations preceding the occurrence and progression of macrofailure are slightly depending on the rock temperature effect. This has been shown through the convolution of some physical precursors in a complex parameter whose variation showed an approaching of macrofailure, which remains slightly influenced by changes in temperature. Our results are interpreted in relation to physics of superficial earthquakes and precursors.