Continuous underground observation of the geomagnetic field in Xuzhou City, North China, and its time-varying characteristics
Underground space in Xuzhou City, North China, has become a favorable site for continuous geomagnetic observation to reveal geomagnetic-field variations and to monitor seismic activity due to its distinct advantage of an “ultra-quiet” and “ultra-clean” environment with low electromagnetic interferen...
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Frontiers Media S.A.
2025-01-01
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| Series: | Frontiers in Earth Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/feart.2024.1505187/full |
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| author | Mei Han Mei Han Lianghui Guo Lianghui Guo Lianghui Guo Yun Wang Yun Wang Xiang Wang Xiang Wang |
| author_facet | Mei Han Mei Han Lianghui Guo Lianghui Guo Lianghui Guo Yun Wang Yun Wang Xiang Wang Xiang Wang |
| author_sort | Mei Han |
| collection | DOAJ |
| description | Underground space in Xuzhou City, North China, has become a favorable site for continuous geomagnetic observation to reveal geomagnetic-field variations and to monitor seismic activity due to its distinct advantage of an “ultra-quiet” and “ultra-clean” environment with low electromagnetic interference. In order to evaluate the underground electromagnetic environment at the Longdong coal mine area (LCMA) in Xuzhou City and establish an underground geomagnetic observatory, we conducted a pilot experiment of continuous geomagnetic observations synchronously underground and on the ground during May 2023. In this experiment, two close-space fluxgate magnetometers were deployed in the underground roadway of the LCMA to observe the variations of geomagnetic three components simultaneously, and a proton magnetometer was installed on its ground to observe the variation of geomagnetic total field. Furthermore, we analyzed the features of the wavelet spectrum of these observed data, variation curves of the geomagnetic field, and coupling of the geomagnetic-field variations between underground and ground. In addition, we investigated the characteristics of different frequency bands and horizontal gradient of the underground geomagnetic variation. Our achievements are as follows: 1) the underground geomagnetic environment has the advantage of being stable and clean with a low level of background noise and thus is suitable for high-precision, long-term, and continuous observation of the geomagnetic field; 2) the variation of the geomagnetic field underground is well coupled with that on the ground, with minor differences primarily attributed to an induced magnetic field generated in the surrounding rocks by the external magnetic-field variation; 3) underground geomagnetic observation can clearly record rich time-varying information of the geomagnetic field including calm variation, magnetic storms, geomagnetic pulsations and so on. Moreover, the geomagnetic gradient field contains higher-resolution time-varying information than the conventional geomagnetic field. Our pilot experiment suggests favorable underground sites with low background noise at the LCMA and provides valuable references for understanding the spatiotemporal variation characteristics of geomagnetic field. Based on the findings of our pilot experiment, an underground geomagnetic observatory and calibration station will be established at the LCMA, enabling high-precision, continuous geomagnetic and electromagnetic observation experiments in the future. These efforts will provide crucial constraints for the study of the variation of the geomagnetic-field variation, as well as seismic activity monitoring and disaster early warning related to the Tan-Lu fault zone. |
| format | Article |
| id | doaj-art-caa830aee414400daecc9797f6e902f1 |
| institution | OA Journals |
| issn | 2296-6463 |
| language | English |
| publishDate | 2025-01-01 |
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| series | Frontiers in Earth Science |
| spelling | doaj-art-caa830aee414400daecc9797f6e902f12025-08-20T02:26:56ZengFrontiers Media S.A.Frontiers in Earth Science2296-64632025-01-011210.3389/feart.2024.15051871505187Continuous underground observation of the geomagnetic field in Xuzhou City, North China, and its time-varying characteristicsMei Han0Mei Han1Lianghui Guo2Lianghui Guo3Lianghui Guo4Yun Wang5Yun Wang6Xiang Wang7Xiang Wang8Key Laboratory of Intraplate Volcanoes and Earthquakes (China University of Geosciences, Beijing), Ministry of Education, Beijing, ChinaSchool of Geophysics and Information Technology, China University of Geosciences (Beijing), Beijing, ChinaKey Laboratory of Intraplate Volcanoes and Earthquakes (China University of Geosciences, Beijing), Ministry of Education, Beijing, ChinaSchool of Geophysics and Information Technology, China University of Geosciences (Beijing), Beijing, ChinaState Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing, ChinaKey Laboratory of Intraplate Volcanoes and Earthquakes (China University of Geosciences, Beijing), Ministry of Education, Beijing, ChinaSchool of Geophysics and Information Technology, China University of Geosciences (Beijing), Beijing, ChinaKey Laboratory of Intraplate Volcanoes and Earthquakes (China University of Geosciences, Beijing), Ministry of Education, Beijing, ChinaSchool of Geophysics and Information Technology, China University of Geosciences (Beijing), Beijing, ChinaUnderground space in Xuzhou City, North China, has become a favorable site for continuous geomagnetic observation to reveal geomagnetic-field variations and to monitor seismic activity due to its distinct advantage of an “ultra-quiet” and “ultra-clean” environment with low electromagnetic interference. In order to evaluate the underground electromagnetic environment at the Longdong coal mine area (LCMA) in Xuzhou City and establish an underground geomagnetic observatory, we conducted a pilot experiment of continuous geomagnetic observations synchronously underground and on the ground during May 2023. In this experiment, two close-space fluxgate magnetometers were deployed in the underground roadway of the LCMA to observe the variations of geomagnetic three components simultaneously, and a proton magnetometer was installed on its ground to observe the variation of geomagnetic total field. Furthermore, we analyzed the features of the wavelet spectrum of these observed data, variation curves of the geomagnetic field, and coupling of the geomagnetic-field variations between underground and ground. In addition, we investigated the characteristics of different frequency bands and horizontal gradient of the underground geomagnetic variation. Our achievements are as follows: 1) the underground geomagnetic environment has the advantage of being stable and clean with a low level of background noise and thus is suitable for high-precision, long-term, and continuous observation of the geomagnetic field; 2) the variation of the geomagnetic field underground is well coupled with that on the ground, with minor differences primarily attributed to an induced magnetic field generated in the surrounding rocks by the external magnetic-field variation; 3) underground geomagnetic observation can clearly record rich time-varying information of the geomagnetic field including calm variation, magnetic storms, geomagnetic pulsations and so on. Moreover, the geomagnetic gradient field contains higher-resolution time-varying information than the conventional geomagnetic field. Our pilot experiment suggests favorable underground sites with low background noise at the LCMA and provides valuable references for understanding the spatiotemporal variation characteristics of geomagnetic field. Based on the findings of our pilot experiment, an underground geomagnetic observatory and calibration station will be established at the LCMA, enabling high-precision, continuous geomagnetic and electromagnetic observation experiments in the future. These efforts will provide crucial constraints for the study of the variation of the geomagnetic-field variation, as well as seismic activity monitoring and disaster early warning related to the Tan-Lu fault zone.https://www.frontiersin.org/articles/10.3389/feart.2024.1505187/fullcontinuous geomagnetic observationthree componentsundergroundtime-varyingNorth China |
| spellingShingle | Mei Han Mei Han Lianghui Guo Lianghui Guo Lianghui Guo Yun Wang Yun Wang Xiang Wang Xiang Wang Continuous underground observation of the geomagnetic field in Xuzhou City, North China, and its time-varying characteristics Frontiers in Earth Science continuous geomagnetic observation three components underground time-varying North China |
| title | Continuous underground observation of the geomagnetic field in Xuzhou City, North China, and its time-varying characteristics |
| title_full | Continuous underground observation of the geomagnetic field in Xuzhou City, North China, and its time-varying characteristics |
| title_fullStr | Continuous underground observation of the geomagnetic field in Xuzhou City, North China, and its time-varying characteristics |
| title_full_unstemmed | Continuous underground observation of the geomagnetic field in Xuzhou City, North China, and its time-varying characteristics |
| title_short | Continuous underground observation of the geomagnetic field in Xuzhou City, North China, and its time-varying characteristics |
| title_sort | continuous underground observation of the geomagnetic field in xuzhou city north china and its time varying characteristics |
| topic | continuous geomagnetic observation three components underground time-varying North China |
| url | https://www.frontiersin.org/articles/10.3389/feart.2024.1505187/full |
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