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| Titel |
Chinese Mobile Geomagnetic Monitoring Array |
| VerfasserIn |
Bin Chen, Zhe Ni, Shuanggui Chen, Jiehao Yuan |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250143124
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| Publikation (Nr.) |
 EGU/EGU2017-6823.pdf |
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| Zusammenfassung |
| From 2010, we have set up Chinese Mobile Geomagnetic Monitoring Array (CMGMA) gradually for seismic monitoring and forecasting. Today, the array includes 973 geomagnetic repeat survey stations, the mean intervals between adjacent 2 stations is about 70km in east of China and 150km in west, covers 7’680’000km2 monitoring eara.
We measure total intensity (F), declination (D) and indensity (I) on each station one time every year, and then remove dural variation using minutely averages data on the nearest observatory and remove main field using “Chinese Geomagnetic Reference Field (CGRF) –Spherical Cap Harmonic model”. After removing secular variation using a natural orthogonal component (NOC) model base hourly averages data from 1995 to now on 31 observatories in China, we calculate the variations of lithosphere magnetic field between each adjacent two years.After analyse the variations of lithoshpere magnetic field before all 25 earthquakes with magnitude bigger than 5 in our monitoring eara, 2 kinds of anomarlies were found during 1-18 months before 20 earthquakes of 25 samples. The first kind was typical called “Quiet Island”, and the variant kind called “frozen area” or “quiet byland”.
The main character of these 2 kind anomalies is the variations of lithosphere magnetic field are smaller near the epicenter than surronding. When we draw the horizontal varistions (ΔBy, ΔBx) as an arrow at level, the variations are identical, scale and direction, in a wide range, as a liquid river flowing from one side to the other.However, the variations near the further epicenter show their difference, with low value and different dirction. Even we have picked these anomlies out before the earthquakes in each July, just soon after our field survey. We are not clear why these nomlies are there, and can not further propose a perfect idea about magnitude and original times. |
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