The Characteristics of Magnetic Signals Observed at Lulin ELF Station and Their Association with Earthquakes in Taiwan
Electromagnetic wave data from years 2009 - 2010 which were recorded by the extremely-low-frequency (ELF) station at Lulin Observatory in Taiwan (120.87°E, 23.46°N; 2862 m) are analyzed to explore the wave properties and their association with seismic and geomagnetic activities. Specifically, the po...
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| Format: | Article |
| Language: | English |
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Springer
2013-01-01
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| Series: | Terrestrial, Atmospheric and Oceanic Sciences |
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| Online Access: |
http://tao.cgu.org.tw/images/attachments/v242p197.pdf
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| _version_ | 1818186924472401920 |
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| author | Shao-Ming Ho Kaiti Wang Alfred B. C. Chen Han-Tzong Su Sung-Ming Huang Ruei-Ron Hsu Tung-Shin Hsu |
| author_facet | Shao-Ming Ho Kaiti Wang Alfred B. C. Chen Han-Tzong Su Sung-Ming Huang Ruei-Ron Hsu Tung-Shin Hsu |
| author_sort | Shao-Ming Ho |
| collection | DOAJ |
| description | Electromagnetic wave data from years 2009 - 2010 which were recorded by the extremely-low-frequency (ELF) station at Lulin Observatory in Taiwan (120.87°E, 23.46°N; 2862 m) are analyzed to explore the wave properties and their association with seismic and geomagnetic activities. Specifically, the power spectra, the ellipticity and the orientation of the below-10-Hz wave signals are studied. The correlation coefficients of these ELF signals and geomagnetic activity indices Dst and Kp are within -0.2 to 0.2, indicating geomagnetic activities are not likely sources for these emissions. In the frequency versus time (f-t) spectrograms, a few events exhibit a frequency shift between 4 and 6 Hz and the possible association with seismic activities of magnitudes (M) larger than 4 in the vicinity of Taiwan are examined. The subset of earthquakes in Taiwan with M/r2 (r is the epicenter distance in kilometer from the Lulin station) of greater than 6 × 10-4, a total number of 50, show a higher association with ELF wave events showing a frequency down-shift within 7 days prior to the earthquakes and a frequency bounce-back within 7 days after the earthquakes. The epicenters of these earthquakes are all within a distance of 100 km from the Lulin station and with a depth of 50 km, suggesting that the detected ELF frequency-shift wave events maybe are pre-earthquake electromagnetic signals. |
| first_indexed | 2024-12-11T23:02:52Z |
| format | Article |
| id | doaj.art-3738aae75778446cb251bd9340f74746 |
| institution | Directory Open Access Journal |
| issn | 1017-0839 2311-7680 |
| language | English |
| last_indexed | 2024-12-11T23:02:52Z |
| publishDate | 2013-01-01 |
| publisher | Springer |
| record_format | Article |
| series | Terrestrial, Atmospheric and Oceanic Sciences |
| spelling | doaj.art-3738aae75778446cb251bd9340f747462022-12-22T00:47:01ZengSpringerTerrestrial, Atmospheric and Oceanic Sciences1017-08392311-76802013-01-0124219710.3319/TAO.2012.09.19.01(SEC)1123The Characteristics of Magnetic Signals Observed at Lulin ELF Station and Their Association with Earthquakes in TaiwanShao-Ming HoKaiti WangAlfred B. C. ChenHan-Tzong SuSung-Ming HuangRuei-Ron HsuTung-Shin HsuElectromagnetic wave data from years 2009 - 2010 which were recorded by the extremely-low-frequency (ELF) station at Lulin Observatory in Taiwan (120.87°E, 23.46°N; 2862 m) are analyzed to explore the wave properties and their association with seismic and geomagnetic activities. Specifically, the power spectra, the ellipticity and the orientation of the below-10-Hz wave signals are studied. The correlation coefficients of these ELF signals and geomagnetic activity indices Dst and Kp are within -0.2 to 0.2, indicating geomagnetic activities are not likely sources for these emissions. In the frequency versus time (f-t) spectrograms, a few events exhibit a frequency shift between 4 and 6 Hz and the possible association with seismic activities of magnitudes (M) larger than 4 in the vicinity of Taiwan are examined. The subset of earthquakes in Taiwan with M/r2 (r is the epicenter distance in kilometer from the Lulin station) of greater than 6 × 10-4, a total number of 50, show a higher association with ELF wave events showing a frequency down-shift within 7 days prior to the earthquakes and a frequency bounce-back within 7 days after the earthquakes. The epicenters of these earthquakes are all within a distance of 100 km from the Lulin station and with a depth of 50 km, suggesting that the detected ELF frequency-shift wave events maybe are pre-earthquake electromagnetic signals. http://tao.cgu.org.tw/images/attachments/v242p197.pdf EarthquakesExtremely-low-frequency (ELF) disturbancesPre-cursor signal |
| spellingShingle | Shao-Ming Ho Kaiti Wang Alfred B. C. Chen Han-Tzong Su Sung-Ming Huang Ruei-Ron Hsu Tung-Shin Hsu The Characteristics of Magnetic Signals Observed at Lulin ELF Station and Their Association with Earthquakes in Taiwan Terrestrial, Atmospheric and Oceanic Sciences Earthquakes Extremely-low-frequency (ELF) disturbances Pre-cursor signal |
| title | The Characteristics of Magnetic Signals Observed at Lulin ELF Station and Their Association with Earthquakes in Taiwan |
| title_full | The Characteristics of Magnetic Signals Observed at Lulin ELF Station and Their Association with Earthquakes in Taiwan |
| title_fullStr | The Characteristics of Magnetic Signals Observed at Lulin ELF Station and Their Association with Earthquakes in Taiwan |
| title_full_unstemmed | The Characteristics of Magnetic Signals Observed at Lulin ELF Station and Their Association with Earthquakes in Taiwan |
| title_short | The Characteristics of Magnetic Signals Observed at Lulin ELF Station and Their Association with Earthquakes in Taiwan |
| title_sort | characteristics of magnetic signals observed at lulin elf station and their association with earthquakes in taiwan |
| topic | Earthquakes Extremely-low-frequency (ELF) disturbances Pre-cursor signal |
| url |
http://tao.cgu.org.tw/images/attachments/v242p197.pdf
|
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