Pre-earthquake signals – Part I: Deviatoric stresses turn rocks into a source of electric currents
Earthquakes are feared because they often strike so suddenly. Yet, there are innumerable reports of pre-earthquake signals. Widespread disagreement exists in the geoscience community how these signals can be generated in the Earth's crust and whether they are early warning signs, related to the...
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| Format: | Article |
| Langue: | English |
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Copernicus Publications
2007-09-01
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| Collection: | Natural Hazards and Earth System Sciences |
| Accès en ligne: | http://www.nat-hazards-earth-syst-sci.net/7/535/2007/nhess-7-535-2007.pdf |
| _version_ | 1828848555902631936 |
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| author | F. T. Freund |
| author_facet | F. T. Freund |
| author_sort | F. T. Freund |
| collection | DOAJ |
| description | Earthquakes are feared because they often strike so suddenly. Yet, there are innumerable reports of pre-earthquake signals. Widespread disagreement exists in the geoscience community how these signals can be generated in the Earth's crust and whether they are early warning signs, related to the build-up of tectonic stresses before major seismic events. Progress in understanding and eventually using these signals has been slow because the underlying physical process or processes are basically not understood. This has changed with the discovery that, when igneous or high-grade metamorphic rocks are subjected to deviatoric stress, dormant electronic charge carriers are activated: electrons and defect electrons. The activation increases the number density of mobile charge carriers in the rocks and, hence, their electric conductivity. The defect electrons are associated with the oxygen anion sublattice and are known as positive holes or pholes for short. The boundary between stressed and unstressed rock acts a potential barrier that lets pholes pass but blocks electrons. Therefore, like electrons and ions in an electrochemical battery, the stress-activated electrons and pholes in the "rock battery" have to flow out in different directions. When the circuit is closed, the battery currents can flow. The discovery of such stress-activated currents in crustal rocks has far-reaching implications for understanding pre-earthquake signals. |
| first_indexed | 2024-12-12T22:32:29Z |
| format | Article |
| id | doaj.art-0b5e2f9a3e044b51ae0f3812d11cb48c |
| institution | Directory Open Access Journal |
| issn | 1561-8633 1684-9981 |
| language | English |
| last_indexed | 2024-12-12T22:32:29Z |
| publishDate | 2007-09-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Natural Hazards and Earth System Sciences |
| spelling | doaj.art-0b5e2f9a3e044b51ae0f3812d11cb48c2022-12-22T00:09:34ZengCopernicus PublicationsNatural Hazards and Earth System Sciences1561-86331684-99812007-09-0175535541Pre-earthquake signals – Part I: Deviatoric stresses turn rocks into a source of electric currentsF. T. FreundEarthquakes are feared because they often strike so suddenly. Yet, there are innumerable reports of pre-earthquake signals. Widespread disagreement exists in the geoscience community how these signals can be generated in the Earth's crust and whether they are early warning signs, related to the build-up of tectonic stresses before major seismic events. Progress in understanding and eventually using these signals has been slow because the underlying physical process or processes are basically not understood. This has changed with the discovery that, when igneous or high-grade metamorphic rocks are subjected to deviatoric stress, dormant electronic charge carriers are activated: electrons and defect electrons. The activation increases the number density of mobile charge carriers in the rocks and, hence, their electric conductivity. The defect electrons are associated with the oxygen anion sublattice and are known as positive holes or pholes for short. The boundary between stressed and unstressed rock acts a potential barrier that lets pholes pass but blocks electrons. Therefore, like electrons and ions in an electrochemical battery, the stress-activated electrons and pholes in the "rock battery" have to flow out in different directions. When the circuit is closed, the battery currents can flow. The discovery of such stress-activated currents in crustal rocks has far-reaching implications for understanding pre-earthquake signals.http://www.nat-hazards-earth-syst-sci.net/7/535/2007/nhess-7-535-2007.pdf |
| spellingShingle | F. T. Freund Pre-earthquake signals – Part I: Deviatoric stresses turn rocks into a source of electric currents Natural Hazards and Earth System Sciences |
| title | Pre-earthquake signals – Part I: Deviatoric stresses turn rocks into a source of electric currents |
| title_full | Pre-earthquake signals – Part I: Deviatoric stresses turn rocks into a source of electric currents |
| title_fullStr | Pre-earthquake signals – Part I: Deviatoric stresses turn rocks into a source of electric currents |
| title_full_unstemmed | Pre-earthquake signals – Part I: Deviatoric stresses turn rocks into a source of electric currents |
| title_short | Pre-earthquake signals – Part I: Deviatoric stresses turn rocks into a source of electric currents |
| title_sort | pre earthquake signals ndash part i deviatoric stresses turn rocks into a source of electric currents |
| url | http://www.nat-hazards-earth-syst-sci.net/7/535/2007/nhess-7-535-2007.pdf |
| work_keys_str_mv | AT ftfreund preearthquakesignalsndashpartideviatoricstressesturnrocksintoasourceofelectriccurrents |