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| Titel |
A multidisciplinary analysis for traces of the last state of earthquake generation in preseismic electromagnetic emissions |
| VerfasserIn |
S. M. Potirakis, G. Minadakis, C. Nomicos, K. Eftaxias |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 11, no. 10 ; Nr. 11, no. 10 (2011-10-26), S.2859-2879 |
| Datensatznummer |
250009739
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| Publikation (Nr.) |
 copernicus.org/nhess-11-2859-2011.pdf |
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| Zusammenfassung |
| Many questions about earthquake (EQ) generation remain standing. Fracture
induced electromagnetic (EM) fields allow real-time monitoring of damage
evolution in materials during mechanical loading. An improved understanding
of the EM precursors has direct implications for the study of EQ generation
processes. An important challenge in this direction is to identify an
observed anomaly in a recorded EM time series as a pre-seismic one and
correspond this to a distinct stage of EQ generation. In previous papers
(Kapiris et al., 2004; Contoyiannis et al.,
2005; Papadimitriou et al., 2008), we have shown that the last kHz part of the
emerged precursory EM activity is rooted in the fracture of the backbone of
asperities distributed along the activated fault, sustaining the system. The
crucial character of this suggestion requires further support. In this work
we focus on this effort. Tools of information theory (Fisher Information)
and concepts of entropy (Shannon and Tsallis entropies) are employed. The
analysis indicates that the launch of the EM precursor is combined with the
appearance of a significantly higher level of organization, which is an
imprint of a corresponding higher level of organization of the local
seismicity preceding the EQ occurrence. We argue that the temporal evolution
of the detected EM precursor is in harmony with the Intermittent Criticality
approach of fracture by means of energy release, correlation length, Hurst
exponent and a power-law exponent obtained from frequency-size distributions
of seismic/electromagnetic avalanche events. The candidate precursory EM
activity is also consistent with other precursors from other disciplines.
Thus, accumulated evidence, including laboratory experiments, strengthen the
consideration that the emergence of the kHz EM precursor is sourced in the
fracture of asperities indicating that EQ occurrence is expected. |
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