Modelling the connection between earthquake preparation processes and crustal electromagnetic emission

Gershenzon, Naum I.; Гохберг, М. Б.; Karakin, A. V.; Petviashvili, N. V.; Rykunov, A. L.

doi:10.1016/0031-9201(89)90222-7

Cited by 39 publications

(15 citation statements)

References 6 publications

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“…12 we find N 1 ∼10 −5 s for L 1 ∼2 km, in result L e ≈0.01-1 m. Just similar range of crack sizes (and corresponding range of frequency F =1-100 kHz) was considered in several papers on fracturing SA emission (e.g. Gershenzon et al, 1989). However, the condition (Eq.…”

Section: Discussionmentioning

confidence: 92%

“…As for ULF foreshocks, we take into account three known models of electromagnetic field generation due to fracturing: the first is CR model, in which charge relaxation during fracture opening is considered (Gershenzon et al, 1989;Molchanov and Hayakawa, 1995); the second (EKE) model is based on mechanism of electro-kinetic conversion in a course of water diffusion just after crack opening in order to compensate changes in high pore pressure around crack (Mizutani et al, 1976;Jouniaux and Pozzi, 1995;Fenoglio et al, 1995) and the third is model of inductive electromagnetic pulses (IP) arising in a course of seismic wave propagation inside the conductive ground medium. This model was proposed by Surkov (1999) and also discussed by Molchanov et al (2001) for explanation of co-seismic ULF magnetic and electric field variations.…”

Section: Discussionmentioning

confidence: 99%

“…Background number rate of seismic pulses in the range of magnitudes from M~7 to about M~3 is described by Gutenberg-Richter relationship: which was exploited in many papers on fracturing emission (e.g. Gershenzon et al, 1989). However, in a case of fardistance activation area we cannot expect any pulses from small-size fractures as it is shown in Fig.…”

Section: Discussionmentioning

confidence: 99%

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Near-seismic effects in ULF fields and seismo-acoustic emission: statistics and explanation

Molchanov

Schekotov

Solovieva

et al. 2005

Nat. Hazards Earth Syst. Sci.

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Part of Special Issue "Precursory phenomena, seismic hazard evaluation and seismo-tectonic electromagnetic effects"Abstract. Preseismic intensification of fracturing has been investigated from occurrence analysis of seismo-acoustic pulses (SA foreshocks) and ULF magnetic pulses (ULF foreshocks) observed in Karimshino station in addition to seismic foreshocks. Such analysis is produced for about 40 rather strong and nearby isolated earthquakes during 2 years of recording. It is found that occurrence rate of SA foreshocks increases in the interval (−12, 0 h) before main shock with 3-times exceeding of background level in the interval (−6, −3 h), and occurrence probability of SA foreshocks (pA∼75%) is higher than probability of seismic foreshocks (ps∼30%) in the same time interval.ULF foreshocks are masked by regular ULF activity at local morning and daytime, nevertheless we have discovered an essential ULF intensity increase in the interval (−3, +1 h) at the frequency range 0.05-0.3 Hz. Estimated occurrence probability of ULF foreshocks is about 40%. After theoretical consideration we conclude: 1) Taking into account the number rate of SA foreshocks, their amplitude and frequency range, they emit due to opening of fractures with size of L=70-200 m (M=1-2); 2) The electro-kinetic effect is the most promising mechanism of ULF foreshocks, but it is efficient only if two special conditions are fulfilled: a) origin of fractures near fluid-saturated places or liquid reservoirs (aquifers); b) appearance of open porosity or initiation of percolation instability; 3) Both SA and ULF magnetic field pulses are related to near-distant fractures (r<20-30 km); 4) Taking into account number rate and activation period of seismic, SA and ULF foreshocks,it is rather probable that opening of fractures and rupture of fluid reservoirs occur in the large preparation area with horizontal size about 100-200 km.

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Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Near-seismic effects in ULF fields and seismo-acoustic emission: statistics and explanation

Molchanov

Schekotov

Solovieva

et al. 2005

Nat. Hazards Earth Syst. Sci.

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“…The VLF-anomalies for the three EQs in KozaniGrevena, Egion-Eratini and Athens differ in their leadtime: as the structure in the pre-focal area becomes less heterogeneous, the lead-time becomes smaller (Eftaxias et al, 2000(Eftaxias et al, , 2001b. Gershenzon et al (1989) have proposed a model for the micro-fracture of granular media consisting of rigid grains and interstices filled with a brittle elastic material. Strong grains can act as crack barriers, whereas the brittle elastic material may enhance crack growth.…”

Section: Discussionmentioning

confidence: 99%

Evolving towards a critical point: A possible electromagnetic way in which the critical regime is reached as the rupture approaches

Kapiris

Eftaxias

Νομικός

et al. 2003

Nonlin. Processes Geophys.

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Abstract. In analogy to the study of critical phase transitions in statistical physics, it has been argued recently that the fracture of heterogeneous materials could be viewed as a critical phenomenon, either at laboratory or at geophysical scales. If the picture of the development of the fracture is correct one may guess that the precursors may reveal the critical approach of the main-shock. When a heterogeneous material is stretched, its evolution towards breaking is characterized by the appearance of microcracks before the final break-up. Microcracks produce both acoustic and electromagnetic (EM) emission in the frequency range from VLF to VHF. The microcracks and the associated acoustic and EM activities constitute the so-called precursors of general fracture. These precursors are detectable not only at laboratory but also at geophysical scales. VLF and VHF acoustic and EM emissions have been reported resulting from volcanic and seismic activities in various geologically distinct regions of the world. In the present work we attempt to establish the hypothesis that the evolution of the Earth's crust towards the critical point takes place not only in a mechanical but also in an electromagnetic sense. In other words, we focus on the possible electromagnetic criticality, which is reached while the catastrophic rupture in the Earth's crust approaches. Our main tool is the monitoring of micro-fractures that occur before the final breakup, by recording their radioelectromagnetic emissions. We show that the spectral power law analysis of the electromagnetic precursors reveals distinguishing signatures of underlying critical dynamics, such as: (i) the emergence of memory effects; (ii) the decrease with time of the anti-persistence behaviour; (iii) the presence of persistence properties in the tail of the sequence of the precursors; and (iv) the acceleration of the precursory electromagnetic energy release. Moreover, the statistical analysis of the amplitudes of the electromagnetic fluctuations reveals the breaking of the symmetry as the theory predicts. Finally, we try to answer the question: how universal the observed Correspondence to: K. A. Eftaxias (ceftax@phys.uoa.gr) electromagnetic critical behaviour of the failing system is?

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“…Through the interaction of the flux of interporous conductive liquid with the field of microcracks, these disturbances can be generated by such a flux (Gershenzon et al, 1993;Molchanov 1995). To achieve a better understanding of the sources, properties and behaviour of the local perturbations, it is important, therefore, to learn to recognize these disturbances.…”

Section: Introductionmentioning

confidence: 99%

Application of a wavelet technique for the detection of earthquake signatures in the geomagnetic field

Alperovich

Zheludev

Hayakawa

2001

Nat. Hazards Earth Syst. Sci.

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Abstract.We developed an algorithm especially adapted to single-station wavelet detection of geomagnetic events, which precede or accompany the earthquakes. The detection problem in this situation is complicated by a great variability of earthquakes and accompanied phenomena, which aggravates finding characteristic features of the events. Therefore we chose to search for the characteristic features of both "disturbed" intervals (containing earthquakes) and "quiet" recordings. In this paper we propose an algorithm for solving the problem of detecting the presence of signals produced by an earthquake via analysis of its signature against the existing database of magnetic signals. To achieve this purpose, we construct the magnetic signature of certain earthquakes using the distribution of the energies among blocks, which consist of wavelet packet coefficients.

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Modelling the connection between earthquake preparation processes and crustal electromagnetic emission

Cited by 39 publications

References 6 publications

Near-seismic effects in ULF fields and seismo-acoustic emission: statistics and explanation

Near-seismic effects in ULF fields and seismo-acoustic emission: statistics and explanation

Evolving towards a critical point: A possible electromagnetic way in which the critical regime is reached as the rupture approaches

Application of a wavelet technique for the detection of earthquake signatures in the geomagnetic field

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