Variation of the geomagnetic harmonic wave amplitude ratio before the MS5.5 Eryuan earthquake in 2013
Li Qi
Yuan Yiren
Yang Xing
Cai Shaoping
Sun Weihuai
Abstract：Based on the 1 second sampling geomagnetic data derived from the eight stations of geomagnetic array in Yunnan Province from June 1,2012 to May 31,2013,the temporal variations of the geomagnetic harmonic wave amplitude ratios were analyzed.It was found that both the geomagnetic har-monic wave amplitude ratios Y ZH y andY HD were enhanced just before the MS 5.5 Eryuan earthquake on 3 March 2013,but no similar variation appeared for the ratio Y ZH x .In order to explain the result,both the temporal evolution of origi-nal vertical components (Z )and the distribution of Weiss vectors were ana-lyzed,and it was found that there was an NS-oriented high conductivity layer on the underground.Considering that the ratios Y ZH y ,Y HD and Y ZH x are related with the variation of NS-oriented conductivity,the heterogeneity of under-ground electrical structure and the variation of EW-oriented conductivity,respec-tively,it was deduced that the variation of the geomagnetic harmonic wave amplitude ratios was closely related to the underground electrical structure.
Keywords：harmonic wave amplitude ratiounderground conductivity struc-turegeomagnetic arraycase study
Publication Date：2016-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：8( 122-129 )