Fractal evolution of MHz electromagnetic signals prior to earthquakes: results collected in Greece during 2009
| Autor: | Ermioni Petraki, Dimitrios Nikolopoulos, Yiannis Chaldeos, Grigorios Koulouras, Constantinos Nomicos, Panayiotis H. Yannakopoulos, Sofia Kottou, John Stonham |
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| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: | |
| Zdroj: | Geomatics, Natural Hazards & Risk, Vol 7, Iss 2, Pp 550-564 (2016) |
| Druh dokumentu: | article |
| ISSN: | 1947-5705 1947-5713 19475705 |
| DOI: | 10.1080/19475705.2014.945496 |
| Popis: | This paper addressed a fractal evolution of 11 one-month lasting MHz electromagnetic disturbances, recorded in Greece prior to nine significant earthquakes of 2009. Time-space wavelet-based power spectral techniques were employed in the analysis. All investigated signals evolved naturally to epochs of fractal organization in space and time. Continuous organization was detected in seven signals. Significant number of successive () power-law -values were observed lying between 1.5 and 3.0 or above. The majority of fractal segments exhibited anti-persistent () or persistent () behaviour. Switching between persistency and anti-persistency was also found. Locality and sensitivity were traced. Findings were considered indicative of self-organized critical states of the last stages of preparation of the investigated earthquakes. Results implied fractional Brownian modelling. Explanations were proposed in view of the asperity model. Persistent–anti-persistent MHz anomalies were due to self-organized micro-cracking of the heterogeneous medium of the earth's crust which may have led the system's evolution towards global failure. The precursory value of the signals was discussed. |
| Databáze: | Directory of Open Access Journals |
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