On the nature, scaling and spectral properties of pre-seismic ULF signals
Earlier work by the authors (Vallianatos and Tzanis, 1999b), has proposed a model for the propagation and scaling of electric earthquake precursors, according to which the pre-seismic electric field emission is due to some time dependent polarisation appearing in an ensemble of electrified crust...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2003-01-01
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| Series: | Natural Hazards and Earth System Sciences |
| Online Access: | http://www.nat-hazards-earth-syst-sci.net/3/237/2003/nhess-3-237-2003.pdf |
| _version_ | 1811338962731532288 |
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| author | F. Vallianatos A. Tzanis |
| author_facet | F. Vallianatos A. Tzanis |
| author_sort | F. Vallianatos |
| collection | DOAJ |
| description | Earlier work by the authors (Vallianatos and Tzanis, 1999b), has proposed a model for the propagation and scaling of electric earthquake precursors, according to which the pre-seismic electric field emission is due to some time dependent polarisation appearing in an ensemble of electrified crustal volumes within the seismogenic source, which are distributed according to a fractal power law. Herein, we extend this formulation to the analysis of ULF magnetic precursors. We calculate the resulting transient magnetic field, which turns out to be mainly vertical and observable only if the seismogenic process generates a source with polarization rate perpendicular to the vertical plane through the source and the receiver. Furthermore, a scaling law between the vertical magnetic field and the magnitude of the associated earthquake is provided. We also investigate the spectral distribution law expected from such a set of emitters. To this effect, we assume that the evolution of the precursory polarisation process is quasi-incoherent over the exited ensemble, i.e. there is no unique relaxation time, but rather a spectrum of these with energy dependence expressed by an Arrhenius law with uniformly distributed energies. We show that the macroscopic ULF field resulting from the superposition of such an ensemble of sources has a power density spectrum distributed proportionally to 1/<i>f</i> . The above theoretical prediction appears to be consistent with independent observations by other investigators. |
| first_indexed | 2024-04-13T18:18:16Z |
| format | Article |
| id | doaj.art-a19805dd0ab14142b8fc01950755cae9 |
| institution | Directory Open Access Journal |
| issn | 1561-8633 1684-9981 |
| language | English |
| last_indexed | 2024-04-13T18:18:16Z |
| publishDate | 2003-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Natural Hazards and Earth System Sciences |
| spelling | doaj.art-a19805dd0ab14142b8fc01950755cae92022-12-22T02:35:35ZengCopernicus PublicationsNatural Hazards and Earth System Sciences1561-86331684-99812003-01-0133/4237242On the nature, scaling and spectral properties of pre-seismic ULF signalsF. VallianatosA. TzanisEarlier work by the authors (Vallianatos and Tzanis, 1999b), has proposed a model for the propagation and scaling of electric earthquake precursors, according to which the pre-seismic electric field emission is due to some time dependent polarisation appearing in an ensemble of electrified crustal volumes within the seismogenic source, which are distributed according to a fractal power law. Herein, we extend this formulation to the analysis of ULF magnetic precursors. We calculate the resulting transient magnetic field, which turns out to be mainly vertical and observable only if the seismogenic process generates a source with polarization rate perpendicular to the vertical plane through the source and the receiver. Furthermore, a scaling law between the vertical magnetic field and the magnitude of the associated earthquake is provided. We also investigate the spectral distribution law expected from such a set of emitters. To this effect, we assume that the evolution of the precursory polarisation process is quasi-incoherent over the exited ensemble, i.e. there is no unique relaxation time, but rather a spectrum of these with energy dependence expressed by an Arrhenius law with uniformly distributed energies. We show that the macroscopic ULF field resulting from the superposition of such an ensemble of sources has a power density spectrum distributed proportionally to 1/<i>f</i> . The above theoretical prediction appears to be consistent with independent observations by other investigators.http://www.nat-hazards-earth-syst-sci.net/3/237/2003/nhess-3-237-2003.pdf |
| spellingShingle | F. Vallianatos A. Tzanis On the nature, scaling and spectral properties of pre-seismic ULF signals Natural Hazards and Earth System Sciences |
| title | On the nature, scaling and spectral properties of pre-seismic ULF signals |
| title_full | On the nature, scaling and spectral properties of pre-seismic ULF signals |
| title_fullStr | On the nature, scaling and spectral properties of pre-seismic ULF signals |
| title_full_unstemmed | On the nature, scaling and spectral properties of pre-seismic ULF signals |
| title_short | On the nature, scaling and spectral properties of pre-seismic ULF signals |
| title_sort | on the nature scaling and spectral properties of pre seismic ulf signals |
| url | http://www.nat-hazards-earth-syst-sci.net/3/237/2003/nhess-3-237-2003.pdf |
| work_keys_str_mv | AT fvallianatos onthenaturescalingandspectralpropertiesofpreseismiculfsignals AT atzanis onthenaturescalingandspectralpropertiesofpreseismiculfsignals |