Long-term magnetic anomalies and their possible relationship to the latest greater Chilean earthquakes in the context of the seismo-electromagnetic theory
<p>Several magnetic measurements and theoretical developments from different research groups have shown certain relationships with worldwide geological processes. Secular variation in geomagnetic cutoff rigidity, magnetic frequencies, or magnetic anomalies have been linked with spatial propert...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2021-06-01
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| Series: | Natural Hazards and Earth System Sciences |
| Online Access: | https://nhess.copernicus.org/articles/21/1785/2021/nhess-21-1785-2021.pdf |
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| author | E. Guillermo Cordaro E. Guillermo Cordaro P. Venegas-Aravena P. Venegas-Aravena P. Venegas-Aravena D. Laroze |
| author_facet | E. Guillermo Cordaro E. Guillermo Cordaro P. Venegas-Aravena P. Venegas-Aravena P. Venegas-Aravena D. Laroze |
| author_sort | E. Guillermo Cordaro |
| collection | DOAJ |
| description | <p>Several magnetic measurements and theoretical developments from different
research groups have shown certain relationships with worldwide geological
processes. Secular variation in geomagnetic cutoff rigidity, magnetic
frequencies, or magnetic anomalies have been linked with spatial properties
of active convergent tectonic margins or earthquake occurrences during
recent years. These include the rise in similar fundamental frequencies in
the range of microhertz before the Maule 2010, Tōhoku 2011, and Sumatra–Andaman 2004
earthquakes and the dramatic rise in the cumulative number of magnetic
anomalous peaks before several earthquakes such as Nepal 2015 and Mexico (Puebla) 2017. Currently, all of these measurements have been physically
explained by the microcrack generation due to uniaxial stress change in rock
experiments. The basic physics of these experiments have been used to
describe the lithospheric behavior in the context of the
seismo-electromagnetic theory. Due to the dramatic increase in experimental
evidence, physical mechanisms, and the theoretical framework, this paper analyzes
vertical magnetic behavior close to the three latest main earthquakes in
Chile: Maule 2010 (<span class="inline-formula"><i>M</i><sub>w</sub></span> 8.8), Iquique 2014 (<span class="inline-formula"><i>M</i><sub>w</sub></span> 8.2), and Illapel 2015 (<span class="inline-formula"><i>M</i><sub>w</sub></span> 8.3).
The fast Fourier transform (FFT), wavelet transform, and daily cumulative number of anomalies methods
were used during quiet space weather time during 1 year before and after
each earthquake in order to filter space influence. The FFT method confirms the
rise in the power spectral density in the millihertz range 1 month before each
earthquake, which decreases to lower values some months after
earthquake occurrence. The cumulative anomaly method exhibited an increase
prior to each Chilean earthquake (50–90 d prior to earthquakes) similar
to those found for Nepal 2015 and Mexico 2017. The wavelet analyses also
show similar properties to FFT analysis. However, the lack of
physics-based constraints in the wavelet analysis does not allow conclusions that are
as strong as those made by FFT and cumulative methods. By using these results and previous
research, it could be stated that these magnetic features could give seismic
information about impending events. Additionally, these results could be
related to the lithosphere–atmosphere–ionosphere coupling (LAIC effect) and
the growth of microcracks and electrification in rocks described by the
seismo-electromagnetic theory.</p> |
| first_indexed | 2024-12-19T10:43:28Z |
| format | Article |
| id | doaj.art-d654763f4e9e47f1a12af37e296f3d14 |
| institution | Directory Open Access Journal |
| issn | 1561-8633 1684-9981 |
| language | English |
| last_indexed | 2024-12-19T10:43:28Z |
| publishDate | 2021-06-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Natural Hazards and Earth System Sciences |
| spelling | doaj.art-d654763f4e9e47f1a12af37e296f3d142022-12-21T20:25:21ZengCopernicus PublicationsNatural Hazards and Earth System Sciences1561-86331684-99812021-06-01211785180610.5194/nhess-21-1785-2021Long-term magnetic anomalies and their possible relationship to the latest greater Chilean earthquakes in the context of the seismo-electromagnetic theoryE. Guillermo Cordaro0E. Guillermo Cordaro1P. Venegas-Aravena2P. Venegas-Aravena3P. Venegas-Aravena4D. Laroze5Observatorios de Radiación Cósmica y Geomagnetismo, Departamento de Física, FCFM, Universidad de Chile, Casilla 487-3, Santiago, ChileFacultad de Ingeniería, Universidad Autónoma de Chile, Pedro de Valdivia 425, Santiago, ChileObservatorios de Radiación Cósmica y Geomagnetismo, Departamento de Física, FCFM, Universidad de Chile, Casilla 487-3, Santiago, ChileDepartment of Structural and Geotechnical Engineering, School of Engineering, Pontificia Universidad Católica de Chile, Vicuña Mackenna 4860, Macul, Santiago, ChileResearch Center for Integrated Disaster Risk Management (CIGIDEN), Santiago, ChileInstituto de Alta Investigación, Universidad de Tarapacá, Casilla 7D, Arica, Chile<p>Several magnetic measurements and theoretical developments from different research groups have shown certain relationships with worldwide geological processes. Secular variation in geomagnetic cutoff rigidity, magnetic frequencies, or magnetic anomalies have been linked with spatial properties of active convergent tectonic margins or earthquake occurrences during recent years. These include the rise in similar fundamental frequencies in the range of microhertz before the Maule 2010, Tōhoku 2011, and Sumatra–Andaman 2004 earthquakes and the dramatic rise in the cumulative number of magnetic anomalous peaks before several earthquakes such as Nepal 2015 and Mexico (Puebla) 2017. Currently, all of these measurements have been physically explained by the microcrack generation due to uniaxial stress change in rock experiments. The basic physics of these experiments have been used to describe the lithospheric behavior in the context of the seismo-electromagnetic theory. Due to the dramatic increase in experimental evidence, physical mechanisms, and the theoretical framework, this paper analyzes vertical magnetic behavior close to the three latest main earthquakes in Chile: Maule 2010 (<span class="inline-formula"><i>M</i><sub>w</sub></span> 8.8), Iquique 2014 (<span class="inline-formula"><i>M</i><sub>w</sub></span> 8.2), and Illapel 2015 (<span class="inline-formula"><i>M</i><sub>w</sub></span> 8.3). The fast Fourier transform (FFT), wavelet transform, and daily cumulative number of anomalies methods were used during quiet space weather time during 1 year before and after each earthquake in order to filter space influence. The FFT method confirms the rise in the power spectral density in the millihertz range 1 month before each earthquake, which decreases to lower values some months after earthquake occurrence. The cumulative anomaly method exhibited an increase prior to each Chilean earthquake (50–90 d prior to earthquakes) similar to those found for Nepal 2015 and Mexico 2017. The wavelet analyses also show similar properties to FFT analysis. However, the lack of physics-based constraints in the wavelet analysis does not allow conclusions that are as strong as those made by FFT and cumulative methods. By using these results and previous research, it could be stated that these magnetic features could give seismic information about impending events. Additionally, these results could be related to the lithosphere–atmosphere–ionosphere coupling (LAIC effect) and the growth of microcracks and electrification in rocks described by the seismo-electromagnetic theory.</p>https://nhess.copernicus.org/articles/21/1785/2021/nhess-21-1785-2021.pdf |
| spellingShingle | E. Guillermo Cordaro E. Guillermo Cordaro P. Venegas-Aravena P. Venegas-Aravena P. Venegas-Aravena D. Laroze Long-term magnetic anomalies and their possible relationship to the latest greater Chilean earthquakes in the context of the seismo-electromagnetic theory Natural Hazards and Earth System Sciences |
| title | Long-term magnetic anomalies and their possible relationship to the latest greater Chilean earthquakes in the context of the seismo-electromagnetic theory |
| title_full | Long-term magnetic anomalies and their possible relationship to the latest greater Chilean earthquakes in the context of the seismo-electromagnetic theory |
| title_fullStr | Long-term magnetic anomalies and their possible relationship to the latest greater Chilean earthquakes in the context of the seismo-electromagnetic theory |
| title_full_unstemmed | Long-term magnetic anomalies and their possible relationship to the latest greater Chilean earthquakes in the context of the seismo-electromagnetic theory |
| title_short | Long-term magnetic anomalies and their possible relationship to the latest greater Chilean earthquakes in the context of the seismo-electromagnetic theory |
| title_sort | long term magnetic anomalies and their possible relationship to the latest greater chilean earthquakes in the context of the seismo electromagnetic theory |
| url | https://nhess.copernicus.org/articles/21/1785/2021/nhess-21-1785-2021.pdf |
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