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The Secular Variation of Geomagnetic Field during 1950-2017 period in Mexico, its comparison with IGRF and analysis of regional Tectonic features |
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Hernandez-Quintero E. (1), Cifuentes-Nava G. (2), Caccavari A. (3) |
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(1) Servicio Magnético, Instituto de Geofísica. Universidad Nacional Autónoma de Mexico |
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In this work, we present the analysis of the secular variation of geomagnetic field in Mexico area during the interval time 1950-2017;the Secular Variation of the geomagnetic field is a phenomenon of internal origin (Jackson, 2009, Constable and Constable, 2000, Mizuno, 1984, or Campbell, 1997); is considered rather global, however, the different observatories in the world registered magnitudes and even absences of the changes in the field (Lanza and Meloni, 2006)in order to carry out the evidence and correlation of global and local geomagnetic features in the area os study. The data base used is the Mexican repeat station network, and historical records from the Teoloyucan magnetic observatory (TEO). Based in the work of Mizuno (1984) the data set was analyzed for horizontal magnetic component (H), declination (D) and intensity (F) as possible. The secular variation behavior using physical measurements is compared with IGRF-12; and the accuracy of the theoretical model fit better for north and central Mexico; nevertheless in south region of the country correlation is poor. The results show that magnetic intensity decreased nearly 8.6% for the studied period; horizontal component presented higher susceptibility during the time analyzed in comparison with declination and intensity.In the maps of secular variation it is possible to recognize two characteristics; one is well defined to the origin of secular variation located in the core mantle boundary. By the other hand a velocity anomaly from tectonic features along the Pacific coast, the Gulf of California ant the Triple Junction in the Gulf of Mexico for instance are described. This study presents a preliminary discussion about the magnetic field behavior in Mexico and its secular variations. |
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